jet biofuel production from agroindustrial wastes...

Jet biofuel production from agroindustrial wastes through furfural

platform

Valentina Aristizábal Marulanda

Universidad Nacional de Colombia Sede Manizales

Instituto de Biotecnología y Agroindustria, Facultad de Ingeniería y Arquitectura,

Departamento de Ingeniería Química

Manizales, Colombia

2015

Producción de biocombustible de avión a partir de residuos

agroindustriales a través de una plataforma de furfural


Universidad Nacional de Colombia Sede Manizales



Manizales, Colombia

2015

Jet biofuel production from agroindustrial wastes through

furfural platform


Thesis submitted in partial fulfillment of the requirements for the degree of:

Master of Science in Engineering - Chemical Engineering

Advisor:

Ph.D., M.Sc, Chemical Engineer Carlos Ariel Cardona Alzate

Co-Advisor:

M. Sc, Chemical Engineer Álvaro Gómez Peña

Research line:

Chemical and Biotechnological Processes Engineering

Research group:

Chemical, Catalytic and Biotechnological Processes

Universidad Nacional de Colombia sede Manizales



Manizales, Colombia

2015

A Dios y a la vida… A mis padres: mi soporte…

A los que se quedaron, a los que se fueron… A la soledad

“Todo con la alegría de poder hacerlo y el placer de triunfar”

IX Jet fuel production from agroindustrial wastes through furfural platform

Acknowledgements

I would like to thank all the people who accompanied me in some way in the development

of the work described in this document. I would like to thank first to my parents who have

believed in me, they have given me support and unconditional love. I express my gratitude

to the small Isa for her hugs full of affection and happiness.

I thank to my academic advisor, Dr. Carlos Ariel Cardona Alzate who has believed in me

and has educated me with exigency and discipline. I want to thank to my co-advisor,

Professor Álvaro Gómez for his accompaniment, availability and advices. I would like to

express my deep gratitude and respect to my research group fellows and friends: Laura,

Javier, Catalina, Héctor, Carlos, Jonathan, Juan Camilo, Angela, Valentina, Miguel, Juan

David, Angela and Paola from the Amazonas who gave me in difficult moments some of

their time for an idea, information or guiding. I appreciate their laughter and long talks.

Thanks to Edu and Alan for their aid. Thanks to Pablito and Yei who have given me a true

friendship and have shared with me more than a nice dinner. Thanks to Eli (my cousin) for

his encouragement and company. I thank to IBA's people, to Denir, Natalia, Diana and

especially to Juan who always had a solution to my problems of experimental installation.

Finally, I want to thanks to institutions and persons associated to financial and operative

support of this thesis: Universidad Nacional de Colombia at Manizales, Facultad de

Ingeniería y Arquitectura, Instituto de Biotecnología y Agroindustria, Laboratorio de

Materiales Nanoestructurados y Funcionales, Laboratorio de Intensificación de Procesos

y Sistema Híbridos, Laboratorio de Magnetismo y Materiales Avanzados and Colciencias

(call 645 - 2014). I would like thank to Dr. María José Cocero Alonso for receiving me at

his laboratory during my internship in Universidad de Valladolid.

X Content

Abstract

The aim of this thesis is the design and analysis of a process to obtain ethanol and jet fuel

or jet fuel bioadditives through furfural platform from lignocellulosic biomass. The

compositional characterization of all feedstocks used is determined. The yields of

experimental procedures are obtained to produce ethanol, furan-based compounds and

derivatives using rice husk, sugarcane bagasse and coffee cut-stems as raw materials.

Simulation procedures based on literature experiences are used to evaluate the production

processes. The analysis presented in this work include techno-economic and

environmental assessments. Also, physicochemical properties of blends of ethanol-

butanol, ethanol-octanol and ethanol-biodiesel are evaluated and compared with properties

of conventional jet fuel to determine their compatibility. As extra work, fique (Furcraea

andina) bagasse is included as raw material for the same process including experimental

evaluation and the simulation procedure.

Keywords: lignocellulosic biomass, jet fuel, bioadditives, ethanol, furfural as

platform, techno-economic and environmental assessment.

Content XI

Resumen

El objetivo de esta tesis es el diseño y análisis del proceso para obtener etanol y

combustible para avión o bioaditivos para combustible a través de una plataforma de

furfural a partir de biomasa lignocelulósica. La caracterización composicional de todas las

materias primas usadas se realizó. Los rendimientos de los procedimientos

experimentales son obtenidos en la producción de etanol, compuestos furanos y derivados

usando cascarilla de arroz, bagazo de caña y zoca de café como materias primas. Se

usaron procedimientos de simulación basados en experiencias reportadas en la literatura

para evaluar los procesos de producción. También, son evaluadas y comparadas las

propiedades fisicoquímicas de las mezclas etanol-butanol, etanol-octanol y etanol-

biodiesel con propiedades de combustible de avión convencional para determinar su

compatibilidad. Como trabajo adicional, se incluyó el bagazo de fique como materia prima

para la evaluación experimental y el procedimiento de simulación.

Palabras claves: biomasa lignocelulósica, combustible para avión, bioaditivos,

etanol, furfural como plataforma, evaluación tecno-económica y ambiental.

Content

Page

Acknowledgements ....................................................................................................... IX

Abstract........................................................................................................................... X

Resumen ........................................................................................................................ XI

Content......................................................................................................................... XIII

List of figures.............................................................................................................. XVII

List of tables ................................................................................................................ XIX

List of publications...................................................................................................... XXI Research Papers ....................................................................................................... XXI Conference Papers .................................................................................................... XXI Oral ..................................................................................................................... XXI Posters .............................................................................................................. XXII Book Chapters ........................................................................................................ XXIV Participation of this Thesis in Research Projects ..................................................... XXIV

Introduction ................................................................................................................ XXV

Thesis hypothesis .................................................................................................... XXVII

Thesis objectives ..................................................................................................... XXVII General Objective .................................................................................................. XXVII Specific Objectives................................................................................................. XXVII

1. Jet biofuels and additives production from lignocellulosic biomass ................. 29 1.1 Overview ............................................................................................................... 29 1.2 Biofuels ............................................................................................................ 29

1.2.1 Bioethanol ...................................................................................................... 32 1.2.2 Biodiesel ........................................................................................................ 33 1.2.3 Biogas ........................................................................................................... 34 1.2.4 Biohydrogen .................................................................................................. 34

1.3 Jet fuels ............................................................................................................ 35 1.4 Additives for jet fuels ........................................................................................ 38 1.5 Bio-additives for jet fuels and jet biofuels .......................................................... 38

1.5.1 Alcohols ......................................................................................................... 39

XIV Jet fuel production from agroindustrial wastes through furfural platform

1.5.2 Alkanes ......................................................................................................... 40 1.5.3 Fatty acid esters ............................................................................................ 40 1.5.4 Biohydrogen .................................................................................................. 41 1.5.5 Biomethane ................................................................................................... 41

1.6 Colombian lignocellulosic biomass .................................................................... 42 1.6.1 Rice husk (RH) .............................................................................................. 44 1.6.2 Sugarcane bagasse (SCB) ............................................................................ 45 1.6.3 Coffee cut-stems (CCS) ................................................................................ 45 1.6.4 Fique bagasse (FB) ....................................................................................... 46

1.7 Final remarks .................................................................................................... 48

2. Materials, Methods and Methodology ................................................................... 49 2.1 Overview ........................................................................................................... 49 2.2 Raw materials ................................................................................................... 49

2.2.1 Rice husk (RH) .............................................................................................. 49 2.2.2 Sugarcane bagasse (SCB) ............................................................................ 50 2.2.3 Coffee cut-stems (CCS) ................................................................................ 50 2.2.4 Fique bagasse (FB) ....................................................................................... 50

2.3 Reagent and raw material characterization methods ......................................... 50 2.3.1 Sample preparation ....................................................................................... 51 2.3.2 Extractives content ........................................................................................ 51 2.3.3 Ash content ................................................................................................... 51 2.3.4 Holocellulose content .................................................................................... 52 2.3.5 Cellulose content ........................................................................................... 52 2.3.6 Lignin content ................................................................................................ 54

2.4 Experimental production of ethanol, furfural and alkane precursor .................... 54 2.4.1 Dilute-acid pretreatment ................................................................................ 54 2.4.2 Enzymatic hydrolysis ..................................................................................... 54 2.4.3 Ethanolic fermentation ................................................................................... 55 2.4.4 Dehydration reaction ..................................................................................... 55 2.4.5 Catalyst preparation ...................................................................................... 55 2.4.6 Aldol-condensation reaction .......................................................................... 56

2.5 Sample analysis ................................................................................................ 56 2.5.1 Sugars and furan-based compounds determination ...................................... 56 2.5.2 Reducing sugars concentration ..................................................................... 57 2.5.3 Ethanol determination.................................................................................... 57 2.5.4 Alkane precursor determination ..................................................................... 57

2.6 Catalyst characterization ................................................................................... 58 2.6.1 X-Ray diffraction ............................................................................................ 58 2.6.2 FT-IR ............................................................................................................. 58 2.6.3 TGA ............................................................................................................... 59 2.6.4 SEM – EDX ................................................................................................... 59

2.7 Determination of physicochemical properties .................................................... 59 2.7.1 Density .......................................................................................................... 59 2.7.2 Viscosity ........................................................................................................ 59 2.7.3 Freezing Point ............................................................................................... 60 2.7.4 Heat Capacity ................................................................................................ 60 2.7.5 Flash point ..................................................................................................... 60

2.8 Process Simulation Description ......................................................................... 61 2.8.1 Techno-economic Assessment ...................................................................... 61 Sugars extraction .......................................................................................... 64

Content XV

Ethanol .......................................................................................................... 64 Butanol .......................................................................................................... 65 Mixture of alcohols ......................................................................................... 65 Furfural .......................................................................................................... 65 HMF ............................................................................................................... 66 Octane ........................................................................................................... 66 Nonane .......................................................................................................... 66 PHB ............................................................................................................... 66 2.8.2 Environmental Assessment ............................................................................. 67

3. Characterization results of lignocellulosic biomass ............................................ 69 3.1 Overview .......................................................................................................... 69 3.2 Results and discussion experimental characterization ...................................... 69

3.2.1 Rice husk (RH) .............................................................................................. 70 3.2.2 Sugarcane Bagasse (SCB) ............................................................................ 70 3.2.3 Coffee Cut-Stems (CCS) ............................................................................... 71 3.2.4 Fique Bagasse (FB) ....................................................................................... 72

3.3 Final remarks ................................................................................................... 73

4. Results physicochemical properties of blends .................................................... 75 4.1 Overview .......................................................................................................... 75 4.2 Results and Discussion .................................................................................... 75 4.3 Final remarks ................................................................................................... 78

5. Experimental results for production of ethanol and furfural from lignocellulosic biomass ................................................................................................................... 81

5.1 Overview .......................................................................................................... 81 5.2 Results and discussion of experimental procedure ........................................... 81

5.2.1 Ethanol production ......................................................................................... 83 5.2.2 Furfural production ......................................................................................... 84 5.2.3 Catalyst characterization ................................................................................ 85 5.2.4 Alkane precursor production .......................................................................... 87

5.3 Final remarks ................................................................................................... 95

6. Techno-economic and environmental assessment for jet biofuels production . 90 6.1 Biorefineries based on coffee cut-stems and sugarcane bagasse: furan-based compounds and alkanes as interesting products ......................................................... 90

6.1.1 Overview........................................................................................................ 90 6.1.2 Biorefineries from sugarcane bagasse and coffee cut-stems ......................... 97 6.1.3 Scenarios and process description ................................................................ 99 6.1.4 Results and Discussion ................................................................................ 105 6.1.5 Conclusions ................................................................................................. 109

6.2 Design and analysis of process schemes based on coffee cut-stems coupled with gasification technology .......................................................................................110

6.2.1 Overview...................................................................................................... 110 6.2.2 Production of ethanol and octane from lignocellulosic biomass .................... 110 6.2.3 Scenarios description................................................................................... 111 6.2.4 Process description ..................................................................................... 113 6.2.5 Results and Discussion ................................................................................ 115 6.2.6 Conclusions ................................................................................................. 118

6.3 Techno-economic and environmental analysis of the processes to obtain blends as additive for jet biofuels ..........................................................................................119

XVI Jet fuel production from agroindustrial wastes through furfural platform

6.3.1 Overview ..................................................................................................... 119 6.3.2 Blends of biofuels as additive for jet fuels .................................................... 119 6.3.3 Process and scenarios description .............................................................. 120 6.3.4 Results and Discussion ............................................................................... 122 6.3.5 Conclusions ................................................................................................. 126

6.4 Lignocellulosic biomass to obtain sugars, ethanol, PHB and energy: Design and analysis of processes ................................................................................................ 127

6.4.1 Overview ..................................................................................................... 127 6.4.2 Second generation biomass to obtain interesting products .......................... 127 6.4.3 Scenarios and process description .............................................................. 128 6.4.4 Results and Discussion ............................................................................... 131 6.4.5 Conclusions ................................................................................................. 137

7. Conclusions ......................................................................................................... 139

A. Annex: Kinetic parameters for simulation procedures ..................................... 141

B. Annex: Analysis of the statics for the furfural synthesis by reactive distillation ............................................................................................................. 145

References .................................................................................................................. 154

List of figures

Page Figure 1-1 Total primary energy supply from 1973 to 2012 by fuels in the world [2], [3]. 30

Figure 1-2 Ethanol and biodiesel world production. Production and prospect (2013-2022)

[4]. .................................................................................................................................. 31

Figure 1-3 Description the feedstocks and biofuels depending on raw material generation.

....................................................................................................................................... 32

Figure 1-4 Production and consumption of ethanol in Colombia. Prospect (2013-2022)

[4]. .................................................................................................................................. 33

Figure 1-5 Production and consumption of biodiesel in Colombia. Prospect (2013-2022)

[4]. .................................................................................................................................. 34

Figure 1-6 Production and consumption of jet fuel in the world [20]. .............................. 36

Figure 1-7 Production and consumption of jet fuel in Colombia [20]. .............................. 36

Figure 1-8 Features of lignocellulosic biomass. Balance between feedstocks and

bioproducts. .................................................................................................................... 43

Figure 1-9 Production of sugarcane and rice in Colombia (2000-2014) [47], [48]. .......... 43

Figure 1-10 Production of coffee and fique at Colombia (2000-2014) [49], [50]. ............. 44

Figure 5-1 Diagram of experimental procedure to obtain ethanol, furfural and alkane

precursor. ....................................................................................................................... 82

Figure 5-2 X-ray diffraction pattern of Mg-OX and ZrO2 [76]. .......................................... 85

Figure 5-3 X-ray spectrum of MgO-ZrO2 obtained in catalyst characterization. .............. 85

Figure 5-4 FT-IR spectrum of MgO-ZrO2. ...................................................................... 86

Figure 5-5 TGA profile of MgO-ZrO2. ............................................................................. 86

Figure 5-6 SEM image of catalyst at 10μm. EDX spectrum and compositional report of

catalyst. .......................................................................................................................... 87

Figure 5-7 Aldol-condensation reaction of furfural and acetone, followed by

hydrogenation of aldol products [39], [40]. ...................................................................... 88

Figure 5-8 GC-MS chromatographs of furfural and monomer when RH is the used as raw

material. ......................................................................................................................... 89

Figure 5-9 GC-MS chromatographs of furfural and monomer when SCB is the used as

raw material. ................................................................................................................... 90

Figure 5-10 GC-MS chromatographs of furfural and monomer when CCS is the used as

raw material. ................................................................................................................... 90

Figure 5-11 GC-MS chromatographs of furfural and monomer when FB is the used as

raw material. ................................................................................................................... 90

XVIII Jet fuel production from agroindustrial wastes through furfural platform

Figure 6-1 Catalytic pathways for furfural conversion. .................................................... 98

Figure 6-2 Catalytic pathways for HMF conversion......................................................... 99

Figure 6-3 Technological scenarios corresponding to the distribution shown in the

scenarios description. ................................................................................................... 100

Figure 6-4 Global economic margins for all scenarios evaluated from SCB and CCS. 107

Figure 6-5 Total potential environmental impact for the different scenarios according to

raw material. ................................................................................................................. 109

Figure 6-6 Process schemes to scenarios 1 and 2 from CCS. ...................................... 113

Figure 6-7 Biomass integrated gasification combined cycle system. 1. Heat exchanger, 2.

Splitter, 3. Compressor, 4. Gas turbine, 5. Dryer, 6. Gasification and combustion

chamber, 7. Cyclone, 8. LP pump, 9. Economizer, 10. LP drum, 11. Evaporator, 12.

Super-heater. ................................................................................................................ 114

Figure 6-8 Energy cost of stream requirement per tonne of CCS based on obtaining

products. ....................................................................................................................... 116

Figure 6-9 Distribution of total costs of process schemes based on CCS. .................... 117

Figure 6-10 Economic margin per scenario and obtained products for process schemes

based on CCS............................................................................................................... 117

Figure 6-11 Process scheme to obtain ethanol and butanol. ........................................ 122

Figure 6-12 Process scheme to obtain ethanol and mixture of alcohols. ...................... 122

Figure 6-13 Global economic margins to obtain ethanol and butanol (Sc. 1) from SCB

and RH.......................................................................................................................... 124

Figure 6-14 Global economic margins to obtain ethanol and mixture of alcohols (Sc. 2)

from SCB and RH. ........................................................................................................ 125

Figure 6-15 PEI per kg of product (ethanol and butanol). ............................................. 125

Figure 6-16 PEI per kg of product (ethanol and mixture of alcohols). ........................... 126

Figure 6-17 Process scheme to obtain glucose and xylose. ......................................... 130

Figure 6-18 Process scheme to obtain ethanol. ............................................................ 130

Figure 6-19 Process scheme to obtain PHB. ................................................................ 130

Figure 6-20 Process scheme to obtain octane and nonane. ......................................... 131

Figure 6-21 Economic margin per raw material of products obtained. .......................... 137

Figure B-1 Separatriz of second order and phase diagram of system .......................... 147

Figure B-2 Chemical interaction and reaction line, case 1. ........................................... 148

Figure B-3 Chemical interaction and reaction line, case 2. ........................................... 148

Figure B-4 P/W in function of pseudoinitial compositions of furfural, case 1. ................ 149

Figure B-5 P/W in function of pseudoinitial compositions of furfural, case 2. ................ 150

Figure B-6 Limit stable state (S1) and technologic scheme, case 1. ............................. 151

Figure B-7 Limit stable state (S1) and their possible trajectories, case 2. Technologic

scheme trajectory 1. ...................................................................................................... 151

Figure B-8 Limit stable state (S2) and technologic scheme, case 2. ............................. 152

Figure B-9 Scheme of process presented in the patent US 20130172583A1 [142]. ..... 152

Content XIX

List of tables

Page Table 1-1 Test flights with addition of biofuels to conventional kerosene. ....................... 41

Table 1-2 Information about geographic sources of crops producing lignocellulosic wastes

studied in this work. ........................................................................................................ 47

Table 2-1 Price/cost of feedstock, utilities and products used in the economic

assessment. ................................................................................................................... 63

Table 3-1 Rice husk composition on a dry basis. ........................................................... 70

Table 3-2 RH chemical characterization reported in literature (wt %). ........................... 70

Table 3-3 Sugarcane bagasse composition on a dry basis. ........................................... 71

Table 3-4 SCB chemical characterization reported in literature (wt %). .......................... 71

Table 3-5 Coffee cut-stems composition on a dry basis. ................................................ 72

Table 3-6 CCS chemical characterization reported in literature (wt %). .......................... 72

Table 3-7 Fique bagasse composition on a dry basis. .................................................... 73

Table 3-8 FB chemical characterization reported in literature (wt %). ............................. 73

Table 4-1 Jet A-1 aviation fuel specifications [119], [120]. .............................................. 76

Table 4-2 Experimental properties for the ethanol-butanol blend in mass fractions. ....... 78

Table 4-3 Experimental properties for the ethanol-octanol blend in mass fractions. ....... 78

Table 4-4 Experimental properties for the ethanol-biodiesel blend in mass fractions. ..... 78

Table 5-1 Results ethanol and furfural production from RH. ........................................... 91

Table 5-2 Results ethanol and furfural production from SCB. ......................................... 92

Table 5-3 Results ethanol and furfural production from CCS. ......................................... 93

Table 5-4 Results ethanol and furfural production from FB............................................. 94

Table 6-1 Scenarios description in biorefineries from SCB and CCS. ...........................102

Table 6-2 Production capacities of top and secondary products per scenario. ..............105

Table 6-3 Production cost of biorefinery products from SCB and CCS. .........................107

Table 6-4 Potential environmental impact for the different scenarios according to raw

material. Human toxicity by ingestion (HTPI), human toxicity by dermal exposition or

inhalation (HTPE), terrestrial toxicity potential (TTP), aquatic toxicity potential (ATP),

global warming (GWP), ozone depletion potential (ODP), photochemical oxidation

potential (PCOP), and acidification potential (AP). .........................................................108

Table 6-5 Scenarios description for process schemes from CCS. .................................112

Table 6-6 Production capacities of top and secondary products per process scheme from

CCS. .............................................................................................................................115

XX Jet fuel production from agroindustrial wastes through furfural platform

Table 6-7 Scenarios description from RH and SCB. ..................................................... 121

Table 6-8 Production capacities of products per scenario. ............................................ 123

Table 6-9 Production cost of products from SCB and RH. ............................................ 123

Table 6-10 Scenarios description to produce sugars, fuel, biopolymer and energy. ...... 129

Table 6-11 Production capacities per scenario from FB and RH. .................................. 132

Table 6-12 Total production cost of glucose and xylose from FB and RH. .................... 133

Table 6-13 Total production cost of ethanol from FB and RH. ....................................... 134

Table 6-14 Total production cost of PHB from FB and RH. ........................................... 135

Table 6-15 Total production cost of Octane and Nonane from FB and RH. ................... 136

Table A-1 Kinetic models used in simulation procedures. ............................................. 141

Table B-1 Boling temperatures of all compounds involved............................................ 146

Table B-2 Conditions of the azeotrope of the system.................................................... 146

Table B-3 Clasification of the fixed points of the system. .............................................. 147

Table B-4 Subregions to direct and indirect separations. .............................................. 147

Table B-5 LSS for direct separation (pseudoinitial compositions and dependence P/W)

case 1. .......................................................................................................................... 149

Table B-6 LSS for direct separation (pseudoinitial compositions and dependence P/W)

case 2. .......................................................................................................................... 150

Content XXI

List of publications

Research Papers

Aristizábal V., Cardona C. A., Gómez A. 2015. Biorefineries based on coffee cut-stems and

sugarcane bagasse: furan-based compounds and alkanes as interesting products. Status:

Submitted. Journal: Bioresource technology.

Conference Papers

Oral

Aristizábal V., Cabrera L. C., Hernández V., Cardona C. A. Producción de biocombustible

para aviones integrado en una biorefinería de bagazo de caña de azúcar. In: Colombia.

Event: Congreso Internacional de Ciencia y Tecnología de los Biocombustibles - CIBSCOL

2014.

Dávila J., Aristizábal V., Castro E., Cardona C. A. Electricity generation from agroindustrial

wastes. Economic point of view. In: Spain. 2014. Event: 4th International Congress on

Green Process Engineering.

Cardona C. A., Aristizábal V., Moncada J. Comparison jet biofuel production from first and

second generation feedstocks. In: Spain. 2014. Event: 10h International Conference on

Renewable Resources & Biorefineries.

XXII Jet fuel production from agroindustrial wastes through furfural platform

Dávila J. Aristizábal V., Moncada J., Cardona C. A. Techno-economic assessment of

hydrogen production from sugarcane waste. In: Spain. 2014. Event: 10h International

Conference on Renewable Resources & Biorefineries.

Cabrera L. C., Aristizábal V., Cardona C. A., Pisarenko Y. Analysis of the statics for the

furfural synthesis by reactive distillation. In: Colombia. 2014. Event: XXVII Congreso

Interamericano y colombiano de Ingeniería Química.

Aristizábal V., Moncada J., Cardona C. A., Gómez A. Analysis of furfural as a platform for

future biorefineries. In: United States. Event: AIChE 2014 Annual Meeting.

Cardona C. A., Aristizábal V., Moncada J., Gómez A. Bioenergy producing biorefineries:

Design and Analysis. In: United States. Event: AIChE 2014 Annual Meeting.

Aristizábal V., Dávila J., Cardona C. A., Gómez A., Aroca G. Techno-economic and

environmental analysis of the use of different biofuel blends to obtain jet biofuels. In: United

States. Event: AIChE 2014 Annual Meeting.

Daza L. Carvajal J. C., Aristizábal V., Cardona C. A. Simultaneous Pretreatment,

Saccharification, Fermentation and Separation Processes to Obtain Ethanol. In: United

States. Event: AIChE 2014 Annual Meeting.

Dávila J., Aristizábal V., Daza L., Rosenberg M., Taborda G., Cardona C. A. Analysis of

the supercritical extraction of anthocyanins. The Andes berry case. In: United States. Event:

AIChE 2014 Annual Meeting.

Posters

Aristizábal V., Carvajal J. C., Cardona C. A. Análisis tecno-ecnonómico de la producción

de biocombustibles y productos de valor agregado bajo el concepto de biorefinería a partir

de cáscara de plátano (Musa paradisiaca AAB). In: Colombia. Event: Congreso

Internacional de Ciencia y Tecnología de los Biocombustibles - CIBSCOL 2014.

Content XXIII

Aristizábal V., Carvajal J. C., Cardona C. A. Lignina como base para futuras biorefinerias

colombianas. In: Colombia. Event: Congreso Internacional de Ciencia y Tecnología de los

Biocombustibles - CIBSCOL 2014.

Aristizábal V., Forero H., Cardona C. A. Sustainable production of jet biofuels in tropical

countries. In: United States. 2014. Event: 36th Symposium on Biotechnology for Fuels and

Chemicals.

Forero H., Aristizábal V., Moncada J., Cardona C. A. Importance of optimal design of

downstream processing in biorefineries. In: Spain. 2014. Event: 10h International

Conference on Renewable Resources & Biorefineries.

Hernández V., Castro E., Aristizábal V., Cardona C. A. Production of biogas and

biofertilizer from wheat straw: A techno-economic and environmental assessment. In:

Czech Republic. Event: 21st International Congress of Chemical and Process Engineering

CHISA 2014.

Aristizábal V., Castro E., Romero-García J. M., Hernández V., Cardona C. A. Techno-

economic assessment of the jet biofuel production from olive stone. In: Czech Republic.

Event: 17th Conference on Process Integration, Modelling and Optimization for Energy

Saving and Pollution Reduction PRES 2014.

Aristizábal V., Moncada J., Cardona C. A. Jet biofuel production from lignocellulosic raw

materials: design and analysis. In: Czech Republic. Event: 21st International Congress of

Chemical and Process Engineering CHISA 2014.

Hernández V., Aristizábal V., Castro E., Cardona C. A. Análisis tecno-económico y

ambiental de la producción de biofertilizantes a partir de residuos cítricos. In: Colombia.

2014. Event: XXVII Congreso Interamericano y colombiano de Ingeniería Química.

Aristizábal V., Carvajal J. C., Dávila J., Cardona C. A. Producción de xilitol y ácido láctico

a partir de cáscara de plátano. In: Colombia. 2014. Event: XXVII Congreso Interamericano

y colombiano de Ingeniería Química.

XXIV Jet fuel production from agroindustrial wastes through furfural platform

Aristizábal V., Idárraga A. M., Carvajal J. C., Cardona C. A. Análisis de la producción de

acetato de etilo por vía química y biológica. In: Colombia. 2014. Event: XXVII Congreso


Restrepo J. B., Aristizábal V., Cardona C. A. Modelado de un sistema bioreactor-extractor

para la producción de biodiesel. In: Colombia. 2014. Event: XXVII Congreso


Aristizábal V., Hernández V., Cardona C. A. Producción de furfural e hidroximetilfurfural a

partir de bagazo de fique. In: Colombia. 2014. Event: XXVII Congreso Interamericano y

colombiano de Ingeniería Química.

Cardona C. A., Forero H., Aristizábal V., Gómez A. Thermodynamic analysis of a

lignocelullose-based furfural biorefinery. In: United States. Event: AIChE 2014 Annual

Meeting.

Book Chapters

Hernández V., Aristizábal V., Cardona C. A. High-cellulose agricultural residues for

biorefineries. In: Agricultural Wastes: Characteristics, Types and Management. Editorial:

Nova Science Publishers, Inc. Status: under review.

Aristizábal V., Hernández V, Cardona C. A. Economic and environmental comparison of

first, second and third generation biorefineries. In: Biorefineries: Sustainable Development,

Applications and Emerging Technologies. Editorial: Nova Science Publishers, Inc. Status:

under review.

Participation of this Thesis in Research Projects

Convocatoria Nacional Jóvenes Investigadores e Innovadores año 2014 of Departamento

Administrativo de Ciencia, Tecnología e Innovación -Colciencias-.

Programa Nacional de Apoyo a Estudiantes de Posgrado para el Fortalecimiento de la

Investigación, Creación e Innovación de la Universidad Nacional de Colombia 2013-2015.

Consultoría para desarrollo de componentes adicionales a las herramientas de evaluación

rápida sobre bioenergía y seguridad alimentaria (BEFS RA) FAO.

Introduction

Nowadays, decrease in oil sources, constant fluctuations and uncertainty of oil prices,

together with environmental concerns are the starting point for energy policies to develop

and produce sustainable, renewable, clean and energy-efficient fuels. Currently, the

population growth has caused an increase in energy demand especially in the

transportation sector. According to United States Energy Information Administration for

2010 the consumption of jet fuel in the world was of 5.2 million barrels per day

approximately. Also, International Air Transport Association (IATA) has fixed as objective

the reduction of emissions of CO2 in 50% for 2050 in aircraft industry. These data, indicate

the necessity of the inclusion of alternative fuels in the aviation industry.

In the past decade, the production of biofuels from feedstocks with low production cost

which do not compete with the worldwide food security have been studied. These

feedstocks play an important role in mitigation of environmental pollution, have high

availability and are potentially sustainable. These reasons indicate that lignocellulosic

biomass is a promising raw material for both biochemicals and fuels. Colombia as tropical

country offers abundance and big variety of raw materials. The diversity of climates zones

allows to farm and produce all type of food. From these crops can be obtained wastes that

in the past were being underused.

Ethanol, biodiesel, butanol, hydrogen and biogas are the main biofuels produced from

lignocellulosic biomass. Recent studies show other attractive possibilities to obtain jet fuels

or additives such as alkanes or mixture of alcohols. The alkanes can be synthesized

through furan-based compounds and the alcohols can be produced by fermentation of

sugars. In addition to the researches done to produce the alternative fuels also studies are

under way to assess compliance with the requirements that have aviation fuels. Some of

features are good burning, free from contaminants, low viscosity, high lubricity and good

thermal and chemical stability.

XXVI Jet fuel production from agroindustrial wastes through furfural platform

In this work, a process design to obtain ethanol and furan-based compounds from four

agroindustrial wastes is presented. Four types of lignocellulosic biomass were selected to

be analyzed as feedstocks to produce jet fuels or jet fuel additives. The chosen feedstocks

were rice husk, sugarcane bagasse, coffee cut-stems and a complimentary fique bagasse.

These residues were selected due to their high content of holocellulosic fiber and

availability. Simulation procedures based on experimental characterization were used to

evaluate the yields of process proposed using the Aspen Plus software. Process

configurations for each waste were evaluated in technical, economic and environmental

terms. In this study, experimentally also were evaluated procedures to obtain ethanol,

furan-based compounds and derivatives. Finally, the physicochemical properties of blends

(ethanol-butanol, ethanol-octanol and ethanol-biodiesel) were analyzed and compared with

properties of conventional jet fuel.

Content XXVII

Thesis hypothesis

It is possible to obtain a jet biofuel with physicochemical properties similar to conventional

jet fuel from lignocellulosic furfural and biofuel blends under biorefinery concept with

Colombian raw materials.

Thesis objectives

General Objective

To design and analyze from the technical, economic and environmental points of view jet

biofuel production from Colombian raw materials.

Specific Objectives

To physicochemically characterize rice husk, sugarcane bagasse and coffee cut-

stems.

To experimentally evaluate ethanol, furfural and intermediates production to obtain

jet biofuel blends.

To evaluate from the technical, economic and environmental point of view jet biofuel

production from biofuel blends and lignocellulosic furfural at Colombian context.

To compare based on experimental physicochemical properties, jet biofuel with

conventional jet fuel.

1. Jet biofuels and additives production from lignocellulosic biomass

1.1 Overview

Currently, there are concerns to reduce the fossil fuel dependence and therefore new

energy sources are being proposed to supply the increasing energy demand. As a

consequence, biomass appears as a promising alternative to produce biofuels, jet fuels and

additives environmentally friendly with competitive advantages over non-renewable fuels.

Among potential biofuels, bioethanol has become one of the most important biofuels as

gasoline additive and widely used in countries such as USA, Brazil and Colombia.

Alternatively, biodiesel also has been a popular biofuel, which is essentially composed of

methyl or ethyl ester of fatty acids and has been used as an additive in diesel in the

transportation sector. Another important biofuel is biobutanol that has gained visibility in

recent years as a replacement for gasoline. Nowadays, the lignocellulosic biomass is the

main source of biofuels because with its content of cellulose, hemicellulose and lignin can

be produced any amount of products including electricity. The raw materials to produce

biofuels have been developed from first generation feedstock (agricultural farming), second

generation (residuals) and third generation (microalgae).

1.2 Biofuels

According to Food and Agriculture Organization of the United Nations – Bioenergy and

Food Security (FAO-BEFS), fuel is defined as an “energy carrier intended for energy

conversion”. Biofuels are liquid fuels that are generated directly or indirectly from biological

materials. A concept that has recently been narrowed, “biofuel is a renewable source of

30 Jet fuel production from agroindustrial wastes through furfural platform

carbon” [1]. Biofuels can be considered one of the most sustainable forms of replacement

for fossil fuels. The first oil crisis (70s) made that several developed and developing

countries started to look for other sources of energy [2]. The biofuels showed up in this

context as an interesting alternative as much from an economic point of view as from the

environmental and social ones. Figure 1-1 shows the global supply of primary energy. The

substantial reduction of oil supply and considerable increase of total energy supply are

significant. Total energy supply jumped from 6106 Mtoe (Million tonnes of oil equivalent) in

1973 to 13371 Mtoe in 2012 [3].

Biofuels are the most effective and efficient option of renewable energy and are composed

of mono-alkyl esters of long chain fatty acids derived from vegetable oils, animal fats and

other non-edible oil sources. Biofuels available in the world are bioethanol, biobutanol,

biodiesel, biohydrogen, biogas, and renewable methanol. Biofuels have special features

such as, mitigation of global warming, low emissions, can provide new incomes and

employment opportunities in rural areas, and are safer.

Figure 1-1 Total primary energy supply from 1973 to 2012 by fuels in the world [2], [3].

*In these graphs, peat and oil shale are aggregated with coal. ** Includes geothermal, solar, wind, heat, etc.

http://en.wikipedia.org/wiki/Tonne_of_oil_equivalent

Chapter 1 31

Figure 1-2 shows ethanol and biodiesel world production in 2015 and prospects until 2022.

There is an interesting linear increase of the prospect of global production for both biofuels.

The availability of feedstock and the enhancement of current techniques are the main

factors that boost this prospect of increasing production and consumption in the coming

years.

Figure 1-2 Ethanol and biodiesel world production. Production and prospect (2013-2022) [4].

Biofuels are usually classified based on feedstock sources. The figure 1-3 shows a brief

description the feedstock and biofuels depending on raw material source. According to the

above the biofuels can be of first generation (1G), second generation (2G), third generation

(3G) and fourth generation (4G) [1] - [5].

First generation (1G) biofuels face social, economic and environmental challenges because

these are derived from food crop feedstocks. Their use can lead to increase food prices

and also to create pressure on land use which makes it unlikely to be totally sustainable.

Additionally, 1G can provide controversial energy balances [1], [6], [7]. Second generation

(2G) biofuels can overcome the social, economic and environmental challenges without

hampering to food cost and creating pressure on land use because it is non-edible,

biodegradable and can grow on marginal land [1], [7], [8]. 2G feedstocks overcome the fuel

vs. food dilemma. Third generation (3G) biofuels, mainly obtained from microalgae have

some remarkable advantages such as being cultured to low-cost, high energy, eco-friendly

and entirely renewable feedstock [1], [9]. Finally, fourth generation (4G) biofuel is an

0

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advanced biofuel based on aromatic and sulphur-free rich fuel with a high cetane blending

value that is fully compatible with oil-derived diesel [5].

Figure 1-3 Description the feedstocks and biofuels depending on raw material generation.

A brief description of main road biofuels currently used in the world is shown below.

1.2.1 Bioethanol

Global ethanol fuel production reached 124000 million liters in 2014 [4], with the US and

Brazil as the world′s top producers, accounting together for 90% of the global production

[10]. World fuel ethanol production during last years is shown in Figure 1-2. The United

States and Brazil remain the two largest producers of ethanol [10]. Corn is the primary

feedstock for US ethanol, and sugarcane is the dominant source of ethanol in Brazil. In

Chapter 1 33

2010, Colombia was the tenth largest producer of ethanol in the world, with a production of

85 million gallons, using sugarcane juice and molasses as feedstock.

Production and consumption of ethanol in Colombia and prospect until 2022 is shown in

figure 1-4. Ethanol can be used as a fuel for vehicles in its pure form, but it is widely used

as a gasoline additive to increase octane and reduce vehicle emissions. In Colombia, the

current blend of ethanol in gasoline is 8% (E8) [1].

Figure 1-4 Production and consumption of ethanol in Colombia. Prospect (2013-2022) [4].

1.2.2 Biodiesel

The Colombian biodiesel production is chiefly based on palm oil. Some new projects

consider other crops such as cotton, soybean and other oil seeds not intended for human

consumption like castor bean and J. curcas. Colombia occupies the fifth place in palm oil

production in the world and the first place in Latin America. Biodiesel is usually used as a

diesel additive to reduce vehicle emissions. In Colombia, biodiesel is added at 7–10%,

depending on the region of the country.

Figure 1-5 shows the prospects of production and consumption of biodiesel in Colombia.

These data show the trend of a gradual increase of biofuel aiming the partial substitution of

petroleum products and reduction of the dependence on foreign energy markets.

0

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2013 2014 2015 2016 2017 2018 2019 2020 2021 2022

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Figure 1-5 Production and consumption of biodiesel in Colombia. Prospect (2013-2022) [4].

1.2.3 Biogas

Biogas is usually 50%-80% methane and 20%-50% carbon dioxide, with traces of gases

such as hydrogen, carbon monoxide, and nitrogen. Biogas can be the versatile and

sustainable energy carrier providing economic security and environmental stability. A large

share of energy crops could be converted into biogas. Compared to fossil transportation

fuels like petrol and diesel, biogas is extremely efficient in reducing overall CO2 emissions

[11]. According to European Biomass Association (AEBIOM) primary biogas production in

the European Union was in 2006 and 2007 in ktoe (thousand tons of oil equivalent) of

4898.9 and 5901.2 respectively [11]. Germany is considered a leader of biogas production.

This country is the leading European biogas producer, accounting for half of the European

primary energy output (50.5% in 2009) and half of the biogas sourced electricity output

(49.9% in 2009) [11]–[13]. Colombia has a very low biogas production at high scale. Usually

biogas is obtained at small scale in some factories.

1.2.4 Biohydrogen

Hydrogen has been identified as a molecule with highest potential as an energy carrier

because it has a higher energy density and can be converted to electricity more efficiently.

Among the biological methods of producing hydrogen, dark fermentation has some

advantages over the photosynthetic and photolytic bioprocesses because of lower net

energy input, higher rate, and moderate yields [14]. Hydrogen is believed by many experts

to be a potential major fuel for transport in the future because of its eco-friendly combustion

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Chapter 1 35

products. However, its main potential for road transport lies in its future role for fuel cell

vehicles and thus it may largely depend on the development of this technology. The

application of hydrogen as an energy source in large scale has been limited due to the

difficulties of finding effective storage material for it. Important advances in storage,

transport infrastructure, fuel cell technology, etc, require costly investment but could

significantly improve performance. At the same time, hydrogen will have to compete with

existing alternatives, such as ethanol and natural gas [15], [16].

1.3 Jet fuels

According to EIA, jet fuel is defined as a refined petroleum product used in jet aircraft

engines. The two main types of aviation fuels are gasoline (avgas) and jet fuel (kerosene)

(C8-16). They are composed mainly of paraffins and cycloparaffins and smaller amounts of

aromatics and olefins along with some additives specified by each category of aviation fuel

[17], [18]. Jet fuels are specialized products that are manufactured according to very tightly

controlled specifications. Jet fuels have special features in comparison with fuels for land

transport. Some requirements of the fuels for aviation use are as follows: good burning

characteristics, free from contaminants, low viscosity and high lubricity, good thermal

stability/chemical stability and wide availability and acceptable cost [19].

Figures 1-6 and 1-7 show the production and consumption of jet fuel in the world and

Colombia respectively. The constant increase of air traffic over the years has increased its

demand and therefore production.


Figure 1-6 Production and consumption of jet fuel in the world [20].

Figure 1-7 Production and consumption of jet fuel in Colombia [20].

Today's kerosene jet fuels have been developed based on the same illuminating kerosene

used in the early gas turbine engines. These engines needed a fuel with good combustion

characteristics and a high energy content [21]. The first fuel specifications appeared in 1943

in the UK and 1944 in the EE.UU. [19]. Fuels specifications have undergone many changes,

mainly related to safety or security of supply until today. There are JP-4, JP-5 and JP-8 for

military use and Jet A-1, Jet A and Jet B for commercial use. The main specifications for

Jet A-1 and Jet A are in ASTM D1655.

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Chapter 1 37

Jet A-1

Jet A-1 is a kerosene grade of fuel suitable for most turbine engine aircraft. It has a minimum

flash point of 38ºC and a maximum freeze point of -47ºC [21], [22].

Jet A

Jet A is a kerosene grade fuel, normally only available in the U.S.A. It has the same flash

point as Jet A-1 but a higher maximum freeze point (-40°C) [21], [22].

Jet B

Jet B is a distillate covering the naphtha and kerosene fractions. It can be used as an

alternative to Jet A-1 but because it is more difficult to handle (higher flammability), there is

only significant demand in very cold climates where its better cold weather performance is

important [21].

JP-4

JP-4 used to be the primary jet fuel for the USAF but was phased out in the 1990s because

of safety problems. A few air forces around the world still use it but there is very little

production. JP-4 is the military equivalent of Jet B with the addition of corrosion inhibitor

and anti-icing additives; it meets the requirements of the U.S. Military Specification MIL-

PRF-5624S Grade JP-4 [21].

JP-8

JP-8 is the military equivalent of Jet A-1 with the addition of corrosion inhibitor and anti-

icing additives; it meets the requirements of the U.S. Military Specification MIL-T-83188D.

It is the dominant military jet fuel grade for NATO air forces [21].

JP-5

JP-5 is a high flash point kerosene meeting the requirements of the U.S. Military

Specification MIL-PRF-5624S Grade JP-5 [21].


Aviation turbine fuels are a complex hydrocarbon mixture consisting of different classes,

such as paraffin (C8-C15), naphthene and aromatics. Bio-aviation fuels are mainly

composed of alkanes that are used as mixing components in aviation turbine fuels, with the

largest proportion being less than 50% according to ASTM D7566.

1.4 Additives for jet fuels

Aviation fuel additives are compounds added to the fuel in very small quantities, usually

measurable only in parts per million, to provide special or improved qualities. The quantity

to be added and approval for its use in various grades of fuel is strictly controlled by the

appropriate specifications. The additive content of jet fuels varies considerably, depending

on whether the fuel is for civil or military use. A few additives in common use are as follows:

anti-knock, antioxidants, static dissipater additives, corrosion inhibitors, icing inhibitors and

metal deactivators [23]. However, it is important to note that any fuel or biofuel that can

fulfill most of the jet fuel requirements can be blended in some proportions and can be

considered jet fuel additives.

1.5 Bio-additives for jet fuels and jet biofuels

Some of the main requirements for alternative fuels are: to reduce greenhouse gas

emissions, to be compatible with conventional fuel, to be sustainable and to produce a clean

burning. However, concerns over the compatibility of the fuel with the aircraft operation

have limited the development of these fuels to date. An alternative fuel must have a number

of characteristics to be considered suitable for aviation. These include the need for a high

energy density, good atomization, rapid evaporation, an ability to be relit at altitude though

a low explosive risk on the ground, they must have a suitably low viscosity, an extremely

low freezing point, good chemical stability, be reasonably non-toxic, be widely available and

economically competitive. Below a description of fuels that can be used in aviation industry

as biofuel and/or bioadditive.

Chapter 1 39

1.5.1 Alcohols

Lignocellulosic ethanol is obtained from sources with low cost and high availability. Also,

the figures 1-2 and 1-4 indicate that the trend in ethanol production is linear for the next

years in the world and Colombia respectively. These factors make it attractive and

interesting for the use as an aviation fuel. The use of ethanol in aviation industry dates

mainly in Brazil [24]. Agricultural aviation and light aircraft, especially in single-engine

airplanes have operated using only ethanol [25]. The replacement of aviation gasoline by

ethanol caused a decrease in operating costs (up to 40%) and environmental improvement.

Monoplanes are driven by piston engines and widely used in the Brazilian agriculture,

representing 75% of sales in the sector. 25% of these aircraft run on ethanol [24], [26].

In commercial aviation, the energy concentration of the fuel is extremely important, and the

use of bioethanol is not particularly desirable for this reason. Additionally, ethanol has high

volatility and low flash point [24], [27], [28]. The growth of ethanol industry, especially in

terrestrial transport opens the door to consider the possibility of studying higher alcohols as

alternative aviation fuels. Higher alcohols offer advantages with respect to energy density,

as the carbon to oxygen ratios growth with increasing molecular mass [24], [27]. n-Butanol,

for example, may be obtained through fermentation of lignocellulosic biomass through the

Acetone–Butanol–Ethanol (ABE) fermentation pathway [6], [29], [30], whereas the use of

modified organisms gives rise to the possibility of producing n-hexanol and higher alcohols

[31]. The n-butanol is considered an attractive fuel for gasoline engines, and has interesting

characteristics for spark ignition engines, demonstrating considerable potential in reducing

GHG emissions [6], [24].

Other alternative use of alcohols in transport industry is the possibility of mixed alcohols as

a fuel additive in gasoline, diesel, jet fuel, aviation gasoline, heating oil, bunker oil, coal,

petroleum coke or as a neat fuel in and of itself [32], [33]. The mixed alcohols formulations

can contain C1-C5 alcohols, or in the alternative, C1-C8 alcohols or higher C1-C10 alcohols

in order to boost energy content [32], [33]. The primary benefits of mixed alcohols are:

increase combustion efficiencies, reduce emissions profiles and low production costs.

According to studies, a jet fuel for use in a jet turbine engine, comprising kerosene and a

mixture of alcohols. The mixture of alcohols comprises by volume 1-30% methanol, 40-75%

ethanol, 10-20% propanol, 4-10% butanol and 1-8% pentanol [32].


1.5.2 Alkanes

Jet fuels range alkanes can be obtained from lignocellulosic biomass by a novel route,

wherein C6 and C5 sugars are firstly produced by hydrolysis of biomass and then converted

into 5-HMF and furfural, respectively, by dehydration step [34]–[38]. Furan-based

compounds are further reacted with acetone by aldol condensation step to produce jet fuel

intermediates, following by the generation of long chain alkanes raging from C7 to C15 via

a dehydration/hydrogenation step. Alkane products from this process have cetane

numbers, a measure of the ignition quality of diesel fuel, ranging from 63 to 97, whereas

the overall cetane number for diesel is typically from 40 to 55. The high cetane numbers for

these biomass-derived alkanes make them excellent blending agents to produce sulfur-free

diesel fuel for transportation applications [38]–[41].

1.5.3 Fatty acid esters

Fatty acid esters (FAEs) are products from the transesterification of triglycerides and fatty

acids of vegetable or animal origin. These can be obtained from raw materials rich in oil as

soybeans, peanut, sunflower, palm, jatropha, canola, microalgae and others. The

properties and characteristics of biodiesel vary considerably depending on the raw material

used and some contaminants may be harmful in the burning of engines [42].

Biodiesel as fuel shows the advantages of high flash point, good energy balance and good

miscibility with petroleum fuels. However, biodiesel is still undergoing many challenges to

become a potential jet fuel due to its high viscosity, its low lower calorific value (LCV) and

high freezing point. In order to meet the specifications required, many test flights have been

conducted with blends of biodiesel and fossil fuels targeting improvements in LCV and

freezing point properties [24], [28], [43]. Fatty acids with short-chain or even with high

number of unsaturations may decrease the problems of high freezing point. Caprylic (C8:0)

and linolenic (C18:3) acids also show an interesting behavior to be used as fuels [27].

In the last years, many tests have been carried out by military aircrafts and airlines in order

to meet the specifications required, as show the Table 1-1. Besides, to test mixture values

with the objective of finding a sustainable solution for the problem of high GHG emission

rates. Biodiesel fuel can be used as a biodiesel fuel and/or additive in other types of fuels

Chapter 1 41

or oils without , including but not limited to: jet fuel, avgas, kerosene, lubrication oil, and fuel

for any 2-stroke engine [44].

Table 1-1 Test flights with addition of biofuels to conventional kerosene.

Year Biomass Biofuel (%) Airline

2005 Soybean 50 Argentine Air Force

2007 N/A Jatropha

100 50

Czech military aircraft Air New Zealand/Boeing/Ross Royce

2008 Coconut/babassu 20 Virgin Atlantic/ Boeing/GE

2009 Algae/jatropha Algae/jatropha/camelina

50 50

Continental Airlines/Boeing/GE-CFM Japan Airlines/Boeing/Pratt & Whitney

2010 Jatropha Halophytes derivatives

50 N/A

TAM Interjet/Airbus

2011 Jatropha/camelina/animal fat

50 Lufthansa

2014 Recycled waste frying oil 20 KLM Royal Dutch Airlines

1.5.4 Biohydrogen

Since 1939 projects have been carried out in Germany aiming to use hydrogen as a fuel

for jet engines. Hydrogen cell technologies stand out among the more efficient and cleaner

ways of transforming electrical energy into transportable energy [24].

Hydrogen is a potentially viable energy source for conventional powertrain applications.

Much of the focus, however, is on pathway applications [45]. Biohydrogen is produced from

a wide range of biomass resources by following both thermal and biochemical methods[14],

[46]. Liquid hydrogen is being established as alternative jet fuel [28]. The combustion of

liquid hydrogen fuels causes low emission of greenhouse gases compared to petroleum

based jet fuels. The major problem is that the liquid hydrogen fuel cannot be used as such

in the conventional aircraft engine so the engine has to be modified [45].

1.5.5 Biomethane

Liquid methane can be used as fuel in cryogenic aircrafts, being considered interesting and

having high energy density in fuel cells. The use of carbon dioxide emission can be

decreased about 25% by the use of liquid methane fuel. Engine design is a difficulty that


has to be faced for the commercialization of the liquid methane fuels. To their use, changes

in engines, injection system and storage of aircrafts are required. The combustion of liquid

methane fuel emits methane, which is a major greenhouse gas [16], [24], [28].

Alternative aviation fuels are produced from renewable bioresources. In this sense, the

section 1.5 shows an overview of main lignocellulosic biomass in Colombia and the features

of raw materials used in this work.

1.6 Colombian lignocellulosic biomass

Colombia as tropical country offers abundance and big variety of raw materials. The

diversity of climate zones allows farming and producing all types of food. From tropical

crops it is possible to obtain wastes that in the past were being underused. These residues

are characterized to have a promising future; this concept implies sustainability based on

low costs and availability. Figure 1-8 shows the synergy of the features of agroindustrial

wastes in the use as raw materials to obtain techno-economic and environmentally feasible

bioproducts. A wide range of feedstocks used for the production of bioenergy, biomaterials

and biochemicals can be obtained in Colombia such as forestry residues (i.e. sawdust,

wood bark) and wastes from agriculture and food processing (i.e. rejected bananas, peel,

seed and whole of fruits, husk, seed and leaves of cotton, husk, pulp and cut-stems of

coffee, husk and straw of rice, bagasse and leaves of sugarcane, and juice and bagasse of

fique, etc).

Chapter 1 43

Figure 1-8 Features of lignocellulosic biomass. Balance between feedstocks and bioproducts.

Rice husk, sugarcane bagasse, coffee cut-stems and fique bagasse were the raw materials

evaluated in this work for the production of ethanol, furfural and alkane precursors. Then,

a brief explication and introduction over the origin, obtaining and potential of each waste.

Initially, figures 1-9 and 1-10 show the production in the last years in Colombia of the source

crops of lignocellulosic biomass studied in this work. Besides, table 1-2 indicates the main

departments and areas where are cultivated, also the wastes and quantity that are

produced.

Figure 1-9 Production of sugarcane and rice in Colombia (2000-2014) [47], [48].

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Figure 1-10 Production of coffee and fique at Colombia (2000-2014) [49], [50].

1.6.1 Rice husk (RH)

In 2014, world rice production could be reached about 501.1 million tonnes (Mt) according

to FAO [51]. The main global rice producers are China, India and Indonesia. In Latin

America, the main crops are in the southern part of the continent. Production in the region

is 19.5 million tonnes with Brazil as main producer followed by Argentina, Colombia,

Ecuador, Guyana and Paraguay [51]. Rice husk is the main waste in the rice agroindustry.

Rice processing generates around 20% rice husk by weight of the total rice production [52].

Amongst the various biomasses, with abundant and renewable energy sources, rice husk

is not only a potential source of energy, but also a value-added byproduct [53]. Rice husk

has unique characteristics in comparison with other agricultural residues, such as high silica

contents and lignocellulosic fibers, high porosity, lightweight and very high external surface

area making it a valuable material for industrial applications. Besides, rice husk can be a

raw material to obtain absorbents, rubber filler and pigments [52]–[54].

Rice husk represents an opportunity for developing projects of clean production and use of

agroindustrial wastes. In Colombia, part of husk which is produced is disposed in vacant

lots causing environmental problems. A priori estimates say that only 5% of husk produced

has an established use. It is necessary to propose integral processes to use this raw

material beginning for example with cogeneration projects to meet energy demand for rice

processing [55], [56].

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Chapter 1 45

1.6.2 Sugarcane bagasse (SCB)

One of the main lignocellulosic materials most abundant in tropical countries is sugarcane

bagasse [52], [57]. Brazil is the biggest producer of sugarcane in the world followed by India

and China. Colombia is the second largest producer in South America [51]. It has been

estimated for 2014/2015 that production will be around 652 million tonnes [57]. In Colombia

there are 13 processing plants of sugarcane, localized mainly at Valle del Cauca. These

plants are the higher producers of crop residues and sugarcane bagasse. Waste production

is between 46 and 50% of total production [55], [58]. One tonne of sugarcane can be

contained around of 26 to 31% of sugarcane bagasse [52], [57]. The residual fraction from the sugarcane stem after juice extraction is named bagasse.

Normally, sugarcane bagasse is used as the main source of the energy required in sugar

mills and ethanol distilleries and also for generating electricity to be sold (94%

approximately) [59]–[61]. However, an important part of the produced bagasse is

underutilized, and it could be used in more than forty different applications, such as

production of pulp and paper, boards and animal feed [62], [63]. The integral utilization of

bagasse components is desirable for both economic and environmental reasons.

1.6.3 Coffee cut-stems (CCS)

Brazil, Colombia, Vietnam, Ethiopia and Indonesia are the biggest producers of coffee in

the world. According to International Coffee Organization (ICO) global production for

2013/2014 was 145.8 million bags [64]. Colombia produced around 12 million bags [49].

Different residues such as pulp, husk, leaves, and coffee grounds are annually generated

in more than 2 million tonnes during the coffee harvesting, processing and final

consumption [65]. Coffee cut-stems is a cut above the land where the coffee plant is

cultivated of 15-20 cm of length and is obtained by crop renewal. Currently, this

lignocellulosic material has not a defined use but can be used as fertilizer, regenerator of

land and manufacture of furniture [65]. Generally the production of these residues is not

concentrated in an only place. For this reason, recent studies have been focused on raising

an optimal exploitation of energy capacity of this raw material taking into account

restrictions in logistics [55], [66].


1.6.4 Fique bagasse (FB)

Venezuela, Costa Rica, Ecuador, Mexico and Colombia are main producers of fique in the

world and this crop is part of his agroindustrial economy. In Colombia are grown about24

mil hectares. These crops are located in the departments of Cauca, Nariño, Caldas,

Antioquia and Santander. Fique bagasse is obtained after fiber extraction of plant. Each

tonne of fique processed generates approximately 70% is juice, 5% fiber and 17% bagasse.

In general, 20.8 tonnes of bagasse and juice are produced by 1 hectare of crop. These

wastes do not have a specific use. Hence, the residual fraction is discard into environment

causing pollution problems [50].

Chapter 1 47

Table 1-2 Information about geographic sources of crops producing lignocellulosic wastes studied in this work.

Crop Colombia grower

regions

Main wastes from

crop Cultivated area (ha)

Waste

(tonnes/year) References

Rice

Oryza sativa

Tolima, Huila, Casanare,

Norte de Santander,

Meta, Bolivar, Arauca and

Sucre

Husk and straw 455,194

(year: 2013)

Rice husk

451,085 [48], [56]

Sugarcane

Saccharum

officinarum L.

Valle del Cauca, Cauca,

Risaralda, Norte de

Santander and Caldas

Bagasse and leaves 225,560

(year: 2014)

Sugarcane bagasse

6,136,765 [47], [58]

Coffee

Coffea arabica

Huila, Antioquia, Tolima,

Cauca and Caldas.

Cut-stems, pulp,

husk, and leaves

948,511

(year: 2014)

Coffee cut-stems

22,000* [49], [66]

Fique

Furcraea andina

Cauca, Nariño, Tolima,

Antioquia and Caldas. Bagasse and juice

18,939

(year: 2011)

Fique bagasse

3,744 [50]

*Eje cafetero


1.7 Final remarks

In the last years, conventional feedstocks (so called first generation) have been changed

by holocellulosic biomass (cellulose and hemicellulose) rich in sugars and source of

biofuels and biofuel components. Tropical and agricultural countries as Colombia have a

potential to produce lignocellulosic biomass. Overall, these wastes do not have the best

collection and disposal system avoiding its full utilization. However, the lignocellulosic

biomass has others competitive advantages as low cost, wide variety and abundance.

Agroindustry wastes do not compete with food security and are constantly produced,

ensuring a stable supply to industry dedicated to convert these raw materials. Sugar crops,

agro and urban/industrial residues show their potential as platform to obtain alternative

energy. These residues in the framework of this thesis can be considered an interesting

feedstocks to obtain different molecules (biofuels and derivatives as those obtained from

furfural) to be blended with jet fuels.

2. Materials, Methods and Methodology

2.1 Overview

Lignocellulosic raw materials have been used in biofuels production as an alternative of

fossil fuels. This chapter describes the potential of raw materials studied in this Thesis, also

the methods used for assessing the different feedstocks and processing routes to produce

sugars, ethanol, furfural and derivatives. In this chapter the simulation procedure, including

the thermodynamic models and technical parameters is shown. On the other hand, a

description of the economic evaluation software is also shown. Finally, the environmental

evaluation packages are also explained. A brief description of the methods used for the raw

material characterization and sample analysis in the experimental setup is developed. All

this together, experimental analysis and simulation procedure help to understand and

design the process routes developed in this Thesis.

2.2 Raw materials


Rice husk (from Oryza Sativa variety) used in this study was obtained as by-product from

a rice mill company located at Tolima Department between the Magdalena and Cauca river

valleys (central zone of Colombia, 2º 52’ 59’’ and 5º 19’ 59’’ N, 74º 24’ 18’’ and 76º 06’ 23’’

W) during July 2014. Tolima has four different climate zones: one semi-wet located at the

Central and Eastern mountain ranges with an annual rainfall higher than 2,000 mm, another

small area from west to southwest is scheduled as slightly wet with an annual rainfall

between 1,500 and 2,000 mm; the area over the Magdalena river valley is considered as

subhumid with an annual rainfall between 1,000 and 1,500 mm and an average temperature

of 24°C.


2.2.2 Sugarcane bagasse (SCB)

Sugarcane bagasse was obtained from a farm placed at Salamina town Caldas

(5°26'02.1"N, 75°28'54.5"W) during April 2014, with altitude about 1,800 meters above

sea level and has an average temperature of 22°C with an average annual rainfall of 1,700

and 1,300 mm.

2.2.3 Coffee cut-stems (CCS)

Coffee Cut-Stems was obtained from a farm placed at La Merced town Caldas

(5°23'19.7"N, 75°32'46.1"W) during June 2014, with an altitude about 1,819 meters above

sea level and has an average temperature of 19°C with an annual rainfall of 1,700 to 1,300

mm.

2.2.4 Fique bagasse (FB)

Fique bagasse was obtained from a farm placed at Salamina town Caldas (5°22'49.2"N,

75°29'29.0"W) during mid-April 2014, with an altitude about 1,800 meters above sea level

and has an average temperature of 22°C with an average annual rainfall of 1,700 and 1,300

mm.

2.3 Reagent and raw material characterization methods

The chemical reagents used for this study were of analytical grade without further

purification. Anhydrous glucose and sodium hydroxide were purchased from Merck. Acetic

acid, sodium and potassium tartrate, sulfuric acid, and anhydrous ethanol were purchased

from Carlo Erba. 3,5-dinitrosalicylic acid (DNS) was bought from Sigma-Aldrich. Sodium

chlorite was obtained from Khemra Technologies.

The physicochemical characterization for whole agroindustrial wastes with three replicates

was carried out. Moisture contents were measured at 105ºC using Shimadzu moisture

balance MOC - 120H.

Chapter 2 51

2.3.1 Sample preparation

Materials have some impurities remaining, therefore these must be removed before their

pretreatment. Materials were dried in an oven (Thermo Precision model 6545) at 45°C

during 24 hours until constant weight. Finally, dried materials were milled (Retsch GmbH

SR200 Gusseisen) to pass 40 mesh (0.4mm) using a Wiley® Mill.

2.3.2 Extractives content

The extractives are chemical products present on cell wall mainly consisting of fats, fatty

acids, fatty alcohols, phenols, terpenes, steroids, resin acids, waxes, etc. They derive their

name as chemicals that are removed by one of several extraction procedures. These

chemicals exist as monomers, dimers and polymers.

According to National Renewable Energy Laboratories (NREL/TP-510-42619) [67], add 2-

10 g of sample to a tared extraction thimble. The height of the biomass in the thimble must

not exceed the height of the Soxhlet siphon tube. Insert the thimble into the Soxhlet tube.

Add 250mL of distilled water to the tared receiving flask with several boiling chips to prevent

bumping. Place the receiving flask on the Soxhlet apparatus. Adjust the heating mantles to

provide a minimum of 4-5 siphon cycles per hour. Carry out the extraction in an extraction

chamber for 24 h. Place them in the oven overnight at temperatures not exceeding 45°C

for 24 h. When dry, remove them to a desiccator for one hour and record the weigh. Repeat

the same procedure in the case of ethanol as solvent.

2.3.3 Ash content

The ash content was determined according to National Renewable Energy Laboratories

(NREL/TP-510-42622) [68]. The ash content of fiber is defined as the residue remaining

after temperature ramp program indicated below: Ramp from room temperature to 105°C.

Hold at 105°C for 12 minutes. Ramp to 250°C at 10°C per minute. Hold at 250°C for 30

minutes. Ramp to 575°C at 20°C per minute. Hold at 575°C for 180 minutes. Allow

temperature to drop to 105°C. Hold at 105°C until samples are removed. After ignition

carefully remove the crucible from the furnace directly into a desiccator and cool. When

cooled to room temperature, record the weigh on the analytical balance.


2.3.4 Holocellulose content

Holocellulose is defined as a water-insoluble carbohydrate fraction of plant materials. The

holocellulose content was determined with the chlorination method described by the ASTM

Standard D1104 [69]. For the assay, the sample should be extractive and moisture free.

To 2.5 g of sample, add 80 mL of hot distilled water, 0.5 mL acetic acid, and 1 g of sodium

chlorite in a 250 mL Erlenmeyer flask. An optional 25 mL Erlenmeyer flask is inverted in the

neck of the reaction flask. The mixture is heated on a water bath at 70°C. After 60 min, 0.5

mL of acetic acid and 1 g of sodium chlorite are added. After each succeeding hour, fresh

portions of 0.5 mL acetic acid and 1 g sodium chlorite are added with shaking. The

delignification process degrades some of the polysaccharides, and the application of

excess chloriting should be avoided. Continued reaction will remove more lignin but

hemicellulose will also be lost. Addition of 0.5 mL acetic acid and 1 g of sodium chlorite is

repeated until the fibers are completely separated from lignin. It usually requires 6 h of

chloriting, and the sample can be left without further addition of acetic acid and sodium

chlorite in the water bath overnight. At the end of 24 h of reaction, the sample is cooled and

the holocellulose content is filtered using a Buchner funnel equipment. The filtration process

is carried out until de yellow color turns into with color and the odor of chlorine dioxide is

removed. The sample is washed with acetone, vacuum-oven dry at 105°C for 24 h, place

in a desiccator for an hour and record the weigh. The holocellulose should not contain any

lignin and the lignin content of holocellulose should be determined and subtracted from the

weight of the prepared holocellulose.

2.3.5 Cellulose content

The preparation of 𝛼-cellulose is a continuous procedure from Procedure 2.3.4 in pursuit of

the ultimately pure form of fiber [69]. Thus the last fraction gives the hemicellulose content.

The sample should be extractive and moisture free.

Weigh out about 2 g of vacuum-oven dried holocellulose and place into a 250 mL glass

beaker provided with a glass cover. Measure 25 mL of 17.5% NaOH solution in a graduated

cylinder and maintain at 20°C. Add 10 mL of 17.5% NaOH solution to the holocellulose in

the 250 mL beaker, cover with a watch glass, and maintain at 20°C in the water bath.

Chapter 2 53

Manipulate the holocellulose lightly with a glass rod with the flat end so that all of the

specimen becomes soaked with the NaOH solution.

After 2 minutes, manipulate the specimen with the glass rod by pressing and stirring until

the particles are separated from one another. After the addition of the first portion of 17.5%

NaOH solution to the specimen, at 5 minute intervals, add 5 mL more of the NaOH solution

and thoroughly stir the mixture with the glass rod, until the NaOH is gone.

Allow the mixture to stand at 20°C for 30 minutes, making the total time for NaOH treatment

45 minutes. Add 33 mL of distilled water at 20°C to the mixture. Thoroughly mix the contents

of the beaker and allow to stand at 20°C for 1 h before filtering.

Filter the cellulose with the aid of suction into the tarred, alkali-resistant fitted-glass crucible

of medium porosity. Transfer the entire holocellulose residue to the crucible, and wash with

100 mL of 8.3% NaOH solution at 20°C. After the NaOH wash solution has passed through

the residue in the crucible, continue the washing at 20°C with distilled water, making certain

that all particles have been transferred from the 250 mL beaker to the crucible. Washing

the sample in the crucible is facilitated by releasing the suction, filling the crucible to within

6 mm of the top with water, carefully breaking up the cellulose mat with a glass rod to

separate any lumps present, and again applying suction. Repeat this step twice.

Pour 15 mL of 10% acetic acid (at room temperature) into the crucible, drawing the acid

into the cellulose by suction but, while the cellulose is still covered with acid, release the

suction. Subject the cellulose to the acid treatment for 3 minutes from the time the suction

is released, then apply suction to draw off the acetic acid. Without releasing the suction, fill

the crucible almost to the top with distilled water at 20°C and allow to drain completely.

Repeat the washing until the cellulose residue is free of acid as indicated by litmus paper.

Give the cellulose a final washing by drawing, by suction, an additional 250 mL of distilled

water through the cellulose in the crucible. Dry the crucible on the bottom and sides with a

cloth and then, together with the weighing bottle in which the sample was originally

weighed, place it overnight in a vacuum oven to dry at 100-105°C. Cool the crucible and

weighing bottle in a desiccator for 1 h before record the weight.


2.3.6 Lignin content

This procedure is a modified version of TAPPI T222 acid-insoluble lignin in wood and pulp

[69]. The sample should be extractive and moisture free.

Accurately weigh out approximately 200 mg of ground vacuum dried sample into a 100 mL

centrifuge tube. To the sample in a 100 mL centrifuge tube, add 1 mL of 72% (w/w) H2SO4

for each 100 mg of sample. Stir and disperse the mixture thoroughly with a glass rod twice,

then incubate the tubes in a water bath at 30°C for 60 minutes. Add 56 mL of distilled water.

This results in a 4% solution for the secondary hydrolysis.

Autoclave at 121°C, 15 psi, for 60 min. Remove the samples from the autoclave and filter

off the lignin, with glass fiber filters (filters were rinsed into crucibles, dried and tarred) in

crucibles using suction, keeping the solution hot. Wash the residue thoroughly with hot

water and dry at 105°C overnight. Move to a desiccator, and let it sit 1 h and record the

weigh.

2.4 Experimental production of ethanol, furfural and alkane precursor

2.4.1 Dilute-acid pretreatment

Acid pretreatment of raw materials was carried out using two operation conditions, i)

sulfuric acid solution (2 %v/v) at 110ºC as reported in [70], [71]. The solid to dilute-acid

solution ratio was 1:10 (w/w), reaction time was 5 h. ii) sulfuric acid solution (10% v/v) at

125ºC as describe in [72]–[74] .The solid dilute-acid solution ratio was 1:10 (w/w), reaction

time was 30 min.

After pretreatment, the solid fractions and liquor were separated by filtration. Solid fraction

was washed eight times using distillated water. This pretreatment was based in

methodology exposed by C. Triana, 2010 [65].

2.4.2 Enzymatic hydrolysis

Enzymatic hydrolysis of cellulose was carried out employing Celluclast 1,5L and

Viscozyme. After acid pretreatment and washing processes, the solid fraction was diluted

with water at 1:10 ratio (%w/w), pH was adjusted with a buffer solution of sodium citrate to

Chapter 2 55

0.05M and pH 4.8. Mass ratio between solid and enzyme was 10:1.5. The sample was

incubated using reciprocal shaking bath model 2870 at 100 rpm and 50ºC of temperature

during 48h. This pretreatment was based in methodology exposed by C. Triana, 2010 & J.

Quintero, 2011 [52], [65]. Finally, the enzymatic hydrolysis was stopped and the hydrolyzed

was vacuum filtrated to remove the solid fraction and the concentration of reducing sugars

was analyzed.

2.4.3 Ethanolic fermentation

Saccharomyces cerevisiae yeast was used as microorganism for ethanolic fermentation of

sugars. After enzymatic hydrolysis and vacuum filtrated, rich-glucose liquor was carried

to autoclave at 120ºC for 20 minutes to sterilize. Fermentations were carried out in 200ml

glass balloons at 32ºC with a fermentation volume of 60ml. For each gram of reducing

sugars was added 4.2 mg of urea, 0.01 mg of magnesium sulphate and ferric chloride.

Ethanol fermentation was started by inoculating the fermentation broth with 5 %v/v of S.

cerevisiae cell at semi-anaerobic conditions. Pre-inoculum was prepared with malt extract

broth.

2.4.4 Dehydration reaction

Dehydration reaction was carried out following these conditions: atmospheric pressure and

at the boiling temperature of an aqueous solution of xylose, with sulfuric acid as catalyst

plus an inorganic salt (NaCl) as promoter. The catalyst and xylose concentration were

according to the conditions of the dilute-acid hydrolysis (i.e., Condition 1: H2SO4 to 2% v/v

and Condition 2: H2SO4 to 10% v/v). The amount of NaCl as promoter was 2.4g based on

data reported by C. Rong et al., 2012 [75]. The experiment was performed by stirring the

aqueous solution with high speed for 1.5 h and was sampled at time 0 and 1.5h.

2.4.5 Catalyst preparation

Catalysts were synthesized by the sol–gel technique, starting from Mg(NO3)2·6H2O (Merck)

and ZrOCl2·8H2O (Merck) and using NaOH as the precipitation agent. Typically, 50.9 g of

magnesium nitrate and 5.2 g of zircomium oxychloride were dissolved in 1L of deionized


water [76]. The mixture was stirred at room temperature, and NaOH (1M) solution was

added until the pH was equal to 10. The resulting gel was aged for 72 h and separated by

vacuum filtration. The precipitate was thoroughly washed with deionized water at least four

times and dried in an oven at 120ºC from 16 to 24 h. The MgO-ZrO2 catalyst was obtained

by calcination of the resulting dry precipitate in 100ml min-1 air flow at 600ºC for 3 h with a

3 h heating ramp. A 5% Pd/MgO-ZrO2 catalyst was prepared by wetness impregnation of

Pd (using 5 %w in Palladium (II) chloride from Sigma Aldrich) onto the above-mentioned

MgO-ZrO2 support. The catalyst was dried in an oven at 100ºC overnight. It was then

calcined in 120ml min-1 air flow at 450ºC for 2 h with a 2 h heating ramp [39], [40], [77], [78].

The catalyst obtained was used for all the aldol-condensation runs, as described below.

2.4.6 Aldol-condensation reaction

Aldol-condensation reaction was carried out in batch reactor and sealed completly

employing Pd/MgO-ZrO2 as catalyst based on data reported by W. Shen et al., 2011 [77].

A 5.5ml reactant solution (55 wt. % total organics, furfural/acetone= 1 by moles,

methanol/water= 1.85 by volume) and 40 mg catalyst were added to the stainless steel

reactor with a total capacity of 11 ml. Next, reactor was heated at 120ºC and pressurized

at 7-10atm for 24h and was sampled at time 0 and 24h. The temperature and pressure

were controlled by an oven (Thermo Precision model 6545) and vapor fraction of the

reactant solution respectively.

2.5 Sample analysis

2.5.1 Sugars and furan-based compounds determination

Sugars and furan-based compounds content during acid hydrolysis, dehydration and

aldolcondensation reactions were quantified by the HPLC system (ELITE LaChrom) using

an ORH-801 Transgenomic® column. Also in aldolcondensation reaction. Sulfuric acid to

0.01N was used as mobile phase. The column oven and RID were maintained at 50ºC, and

flow rate for mobile phase was fixed at 0.8 ml min-1 [79]. The samples were centrifuged,

diluted and filtered using membrane GV (Durapore) 0.22μm of pore and 13mm of diameter

into the HPLC vials. Peaks were detected by the RI detector and quantified on the basis of

area and retention time of the standards (glucose, xylose, furfural and HMF) procured from

Chapter 2 57

Merck, Sigma–Aldrich and Acros Organics. The procedure was carried out in the

Laboratorio de Intensificación de Procesos y Sistemas Híbridos, Universidad Nacional de

Colombia sede Manizales.

2.5.2 Reducing sugars concentration

DNS method was used for determining the total reducing sugar content during enzymatic

hydrolysis and ethanolic fermentation. The reducing sugars were quantified by the 3,5-

Dinitrosalicylic acid (DNS) method with a Jenway 6405 UV/Vis Spectrophotometer. The

sample 1:20 in DNS reagent in a test tube were diluted and mixed. Tubes were placed in

boiling water bath for 9 minutes, transferred to ice to rapidly cool down for 3 minutes. Then,

absorbance was measured at a wavelength of 540 nm, against a blank. A calibration curve

was made from an anhydrous glucose standard solution (1, 2, 3, 4 and 5 g L-1) and the

blank was prepared with distilled water.

2.5.3 Ethanol determination

Ethanol were quantified by the HPLC system (ELITE LaChrom) using an ORH-801

Transgenomic® column. Sulfuric acid to 0.01N was used as mobile phase. The column

oven and RID were maintained at 35ºC, and flow rate for mobile phase was fixed at 0.8 ml

min-1 [79]. The samples were centrifuged, diluted and filtered using membrane GV

(Durapore) 0.22μm of pore and 13mm of diameter into the HPLC vials. Peaks were

detected by the RI detector and quantified on the basis of area and retention time of the

standard (ethanol) procured from Merck. The procedure was carried out in the Laboratorio

de Intensificación de Procesos y Sistemas Híbridos, Universidad Nacional de Colombia

sede Manizales.

2.5.4 Alkane precursor determination

Alkane precursor (4-(2-furyl)-3-buten-2-one) identification was based on mass spectra (EI,

70 eV) obtained with a gas chromatograph (Agilent Technologies 6850 Series II) equipped

with a mass selective detector (MSD 5975B). The injector temperature was kept at 250 °C.

The chromatographic separation was performed using a HP-5MS capillary column

(30 m × 0.25 mm i.d., 0.25 μm film thickness). Helium (99.99%) was used as the carrier


gas with a constant flow rate of 1 mL min-1 and a 1:100 split ratio. The GC oven temperature

was programmed from 40 °C (2 min) to 250 °C with the heating rate of 5 °C min-1, and hold

up during 2 min. The temperature of the GC/MS interface was held at 250 °C. Mass spectra

and reconstructed chromatograms were obtained by automatic scanning in the mass

range m/z 40–350 at 3.5 scan s−1. Chromatographic peaks were checked for homogeneity

with the aid of the mass chromatograms for the characteristic fragment ions. The procedure

was made according to reported by Z. Krkosová et al., 2007 [80] with some modifications

and was carried out in the Laboratorio de Instrumental of the Instituto de Biotecnología y

Agroindustria –IBA–, Universidad Nacional de Colombia sede Manizales.

2.6 Catalyst characterization

2.6.1 X-Ray diffraction

X-ray analysis of solids was carried out using a Rigaku Miniflex II diffractometer. The

patterns were run with copper radiation (λ = 1.5406 A) at 30 kV and 15 mA; the diffraction

angle 2θ between 3-70° was scanned at a rate of 5ºC min−1 [39], [76], [77]. The procedure

was carried out in the Laboratorio de Materiales Nanoestructurados y Funcionales,

Universidad Nacional de Colombia at Manizales.

2.6.2 FT-IR

The Fourier transform infrared spectrum (FT-IR) of sample was performed by means of a

spectrometer Nicolet iS5 (Thermo Scientific, Madison, US) with a Transmission iD1

accessory using KBr pellet. Data were collected over 64 scans with a resolution of 4 cm-1

in the range 4,000 to 400 cm-1 [76], [81]. The procedure was carried out in the Laboratorio

de Instrumental of the Instituto de Biotecnología y Agroindustria –IBA–, Universidad

Nacional de Colombia at Manizales.

Chapter 2 59

2.6.3 TGA

Thermogravimetric analysis was performed in a TGA Q500 TA Instruments. The TG curves

were carried out under dynamic nitrogen atmosphere (50 mL min-1). Temperature was

increased from 25 up to 800ºC at 10ºC min-1. The procedure was carried out in the

Laboratorio de Magnetismo y Materiales Avanzados, Universidad Nacional de Colombia at

Manizales.

2.6.4 SEM – EDX

Scanning electron microscopy coupled with energy dispersive X-ray (SEM/EDX)

spectroscopy analysis was carried out in a FEI, Quanta 250 with digital image acquisition

to study the surface morphology. The procedure was carried out in the Instituto de

Investigaciones en Estratigrafía, Universidad de Caldas.

2.7 Determination of physicochemical properties

2.7.1 Density

Density was determined according to Standard Test Method for Density, Relative Density

and API Gravity of Liquids (ASTM D4052) [82]. Record the weight of pycnometer of known

volume. Add the sample into the apparatus until the gauging. Insert the apparatus into the

water bath. After insertion, allows the pycnometer to reach bath temperature (15ºC). When

reaches the temperature record the weight again. Density is the result of difference between

the final and initial weight measure divided by the volume of the pycnometer.

2.7.2 Viscosity

Viscosity was determined according to Standard Test Method for Kinematic Viscosity of

Transparent and Opaque Liquids (ASTM D445-12) [83]. 15 ml of sample were added to

Ostwald’s viscometer through the larger diameter tube and was inserted the apparatus into

the bath. After insertion, was allowed that the viscometer to will reach bath temperature (-

20ºC). When reached the temperature, the liquid was aspirated above the upper mark of

the smaller diameter tube. The time it takes the sample to pass between the gauging 1 and


2 was measured. Viscosity was the result of multiplying the constant parameter given by

the viscometer according to size and the measured time. Viscometer sizes were 1 and 1C

and constant respective is 0.01048 and 0.03034 mm2 s-2 (cSt s-1).

2.7.3 Freezing Point

Freezing point was determined according to Standard Test Method for Freezing Point of

Aviation Fuels (ASTM D2386-06) [84]. 15 ml of sample was transferred to a test tube. The

apparatus was inserted into the bath while the temperature descended gradually. The

sample was observed continuously until appearance of crystals. The temperature was

recorded when the crystals completely appeared.

2.7.4 Heat Capacity

The thermal treatment of samples was carried out in-situ, in DSC-Q100 TA instruments.

The MDSC curves were performed under nitrogen atmosphere (50ml min-1). Samples were

prepared in aluminum hermetic DSC capsule. Once sealed, it was allowed to equilibrate for

30 minutes to assure stabilization. An empty capsule was used as reference. The samples

were tested in MDSC ramps from 25 to 70ºC, for 5ºC min-1.

2.7.5 Flash point

Flash point was determined according to Standard Test Method for Flash Point by Pensky-

Martens closed cup tester (ASTM D93) [85]. The cup was filled with the sample being tested

up to the level indicated by filling mark. The lid was put on the cup and was left the cup

inside the stove. The thermometer was inserted into the thermometer port. The test flame

was lit with an external ignition source and was adjusted the flame. The stirrer was

connected to the stirrer motor to homogenize the sample. The stirrer motor during the

application of the test flame was turned off. The test flame was applied at each temperature

reading by turning the fiber knob clockwise. The cover assembly was opened and the test

flame was immersed into the sample cup. The temperature was recorded when the flash

point occurred. The proofs were made in K16200 flash point tester assembly (115V Model).

Chapter 2 61

2.8 Process Simulation Description

2.8.1 Techno-economic Assessment

For a given scenario, flowsheet synthesis was carried out using process simulation tools.

The objective of this procedure was to generate the mass and energy balances from which

the requirements for raw materials, consumables, utilities and energy needs are calculated.

The main simulation tool used was the commercial package Aspen Plus v8.2 (Aspen

Technology, Inc., USA). Specialized package for performing mathematical calculations

especially for kinetic analysis such as Matlab was also used. The acid and enzymatic

hydrolysis were calculated using the kinetic models reported by Huang et al. (2011) [70]

and Morales-Rodriguez et al. (2011) [86] respectively. The fermentation stage for fuel

ethanol production was calculated using the kinetic model reported by Rivera et al. (2006)

[87] when Saccharomyces cerevisiae is considered and the kinetic model reported by

Rogers et al. (2001) [88] when Zymomonas mobilis is used as microorganism. Kinetic

model for detoxification were reported by Martinez et al. (2001) [89]. The kinetic model used

for the calculation of PHB production was reported by Shahhosseini (2004) [90]. For some

products (furfural, HMF, octane and nonane) reaction conditions were adapted from

different studies [41], [89] - [91]. One of the most important issues to be considered during

the simulation procedure is the appropriate selection of the thermodynamic models that

describe the liquid and vapor phases. Non-Random Two-Liquid (NRTL) thermodynamic

model was applied to calculate the activity coefficients of the liquid phase and the Hayden-

O’Connell equation of state was used for description of the vapor phase. The most selected

model for this issue was UNIFAC-DORTMUND for liquid phase and Soave Redlick Kwong

for vapor phase.

The estimation of the energy consumption was performed based on the results of the mass

and energy balances generated by the simulation. For this purpose, the thermal energy

required in the heat exchangers and re-boilers was taken into account, as well as the

electric energy needs of the pumps, compressors, mills and other equipments. The capital

and operating costs were calculated using the Aspen Process Economic Analyzer v8.2

software (Aspen Technologies, Inc., USA). This analysis was estimated in US dollars for a

10-year period at an annual interest rate of 17% (typical for the Colombian economy),

considering the straight line depreciation method and a 25% income tax. Prices and


economic data used in this analysis correspond to Colombian conditions such as the costs

of the raw materials, income tax, labour salaries, among others, were incorporated in order

to calculate the production costs per kilogram of product. Table 2-1 summarizes the

economic data used in the different process configuration.

Chapter 2 63

Table 2-1 Price/cost of feedstock, utilities and products used in the economic assessment.

Item Unit Price Reference

Rice husk USD ton-1 5 [92]

Sugarcane bagasse USD ton-1 15 [92]

Coffee cut-stems USD ton-1 18 [92]

Fique bagasse USD ton-1 5.7 +

Ethanol USD kg-1 1.07 [93]

Butanol USD kg-1 1.9 [94]

Octanol USD kg-1 1.68 [94]

Furfural USD kg-1 1.7 [94]

5-HMF USD kg-1 2.0 [94]

Octane USD kg-1 7.0 [94]

Nonane USD kg-1 22.5 [94]

Sulfuric acid USD kg-1 0.094 [95]

Calcium hydroxide USD kg-1 0.07 [95]

Acetone USD kg-1 0.97 [95]

Toluene USD kg-1 0.85 [95]

Hydrogen USD kg-1 9.26 [94]

Dimethyl sulfoxide USD kg-1 1.0 [94]

Butanol USD kg-1 1.9 [94]

Glucose USD kg-1 0.8 [94]

Xylose USD kg-1 1.5 [94]

PHB USD kg-1 3.5 [94]

Mixture of alcohols USD kg-1 2.91 +

Mid P. Steam (30bar) USD ton-1 8.18 [96]

Low P. Steam (3bar) USD ton-1 1.57 [96]

Fuel USD/MEGAWatt 24.58 [97]

Water USD m-3 0.74 *

Electricity USD/kWh 0.14 *

Operator labor USD h-1 2.56 *

Supervisor labor USD h-1 5.12 *

+ Estimate.

*Typical prices in Colombia.


Following is in detail the description of processes used to produce glucose, xylose, ethanol,

butanol, mixture of alcohols, furfural, HMF, octane, nonane and PHB.

Sugars extraction

Lignocellulosic biomass is submitted to a process consisting in three stages as follow

described: i) size reduction and pretreatment, ii) dilute-acid pretreatment and iii) enzymatic

hydrolysis. The first stage of the process involved a size reduction stage in which the

expected final particle diameter was 1 mm. After milling and sieving, in the second stage

the hemicellulose fraction is hydrolyzed with sulfuric acid (2% by weight) based on the

kinetic expressions reported by Huang et al. (2011) [70] at 100 °C. This process is carried

out in a single reactor. The result of this hydrolysis is a non-converted solid fraction and a

rich-pentose liquor which is separated by filtration. Finally in the third stage, the solid

fraction rich in cellulose and lignin is submitted to an enzymatic hydrolysis step based on

the kinetic expressions reported by Morales-Rodriguez et al. (2011) [86] at 35°C to obtain

a rich-hexoses liquor and a solid residue rich in lignin.

As a by-product in the dilute-acid pretreatment, furfural and HMF are obtained as a result

of the decomposition reactions of sugars. Then, detoxification technology is applied [98],

[99]. This procedure is carried out to avoid poisoning and inhibition by the acids, furfural

and HMF in the fermentation stage where Z. mobilis is used as microorganism.

Ethanol

The fermentation step is carried out with Saccharomyces cerevisiae when hexoses are

considered as feedstock. On the other hand, as an alternative Zymomonas mobilis is used

as fermentation microorganism for ethanol production using pentoses as feedstock

(scenario 4). Initially rich-sugar liquor is sent to a sterilization process at 121°C in which the

biological activity is neutralized. Later the fermentation process is carried out based on the

kinetic expressions reported by Rivera et al. (2006) [87] and Rogers et al. (2001) [88], using

Saccharomyces cerevisiae at 37ºC and Zymomonas mobilis at 30ºC as microorganisms

respectively. Afterwards, cell biomass is separated from the culture broth by a simple

gravitational sedimentation technology. After the fermentation stage, the culture broth

containing approximately 5-10% (wt/wt) of ethanol is taken to the separation step, which

Chapter 2 65

consists of two distillation columns. In the first column, ethanol is concentrated nearly to 45-

50% by weight. In the second column, the liquor is concentrated until the azeotropic point

(96% wt) to be led to the dehydration step with molecular sieves to obtain an ethanol

concentration of 99.6% by weight [100].

Butanol

Rich-hexoses liquor is sent to sterilization process at 121°C in which the biologic activity is

neutralized. Then, the ABE fermentation process is carried out based on the kinetic

expressions reported by (van der Merwe 2010), at 33°C using C. acetobutylicum as

microorganism. Afterwards, cell biomass is separated from the culture broth containing

approximately 5% (wt/wt) of butanol. The resulting stream is taken to the separation zone,

which consists of three distillation columns. In the first column, some organic components

and the most of the water are removed, concentrating the butanol up to 53%. The second

column removes acetone and ethanol, obtaining butanol is at 69%. Finally, in the third

column of the mixture water-butanol is separated for obtaining butanol at a concentration

of 90% by weight (van der Merwe 2010) [101].

Mixture of alcohols

The process to obtain mixture of alcohols is composed by three stages, i) dehydration

process of ethanol to obtain ethylene at 450ºC, ii) Ziegler process in presence of oxygen

and aluminum to form triethylaluminum, and iii) oxidation process to form an alcohols mix

at 290ºC and 25bar [102].

Furfural

Furfural is obtained from rich-pentose liquor via xylose dehydration, catalyzed by aluminum

and hafnium pillared clays with 86.2% of conversion [103] and using air as stripping agent

for removing the product while is produced [91]. First the liquor is sent to a reactor at 170°C

and 10bar. Air is fed into the reactor at a ratio of 30:1 air to feed. The resulting stream is

depressurized to recover the liquid fraction. Then, the mixture is sent to a liquid-liquid

extraction process with toluene as solvent with 1:1 v/v ratio to recover the furfural from the

water. Finally, the solvent-furfural stream is submitted to a distillation process where the

furfural is obtained as bottom product [91].


HMF

HMF is obtained from rich-hexose liquor via glucose dehydration, through a non-catalyzed

system in water as describe Jing et al. (2008) [104]. Liquor is sent to a reactor at 220ºC

and 10MPa. The resulting stream is the depressurized. Then, the mixture is sent to a liquid-

liquid process with dimethyl sulfoxide (DMSO) as solvent with 1:0.6 molar ratio to recover

the HMF from water. Finally, the solvent-HMF stream is submitted to a distillation process

where the HMF is obtained as bottom product [105], [106].

Octane

Octane is obtained from furfural. The process to obtain octane is described in three steps:

1) aldol-condensation of furfural with acetone over MgO/NaY as catalyst at 85ºC as

describe Wang et al. (2012) [38], 2) mild hydrogenation of aldol products at 140ºC and

2.5MPa catalyzed by Pt/Co2AlO4 as describe Lu et al. (2011) [41] and 3)

dehydration/hydrogenation to liquid alkanes at 170ºC and 2.5MPa [41]. Finally, octane at

82% is obtained by distillation.

Nonane

Nonane is obtained from HMF. The process to obtain nonane is described in three steps:

1) aldol-condensation of HMF with acetone (molar ratio of 1:10) over MgO/ZrO2 as catalyst

at 50ºC as described Dumesic et al. (2007) [40] 2) hydrogenation of aldol products in

supercritical carbon dioxide in the presence of Pd/Si-Al-MCM-41 catalyst at 80ºC and

12MPa as describe Chatterjee et al. (2008) [107] and 3) dehydrogenation/hydrogenation to

liquid alkanes at 80ºC [107]. Finally, nonane at 88% is obtained by distillation.

PHB

Initially rich-hexose liquor is sent to a sterilization process at 121°C in which the biological

activity is neutralized also involving a nitrogen source ((NH4)2SO4). The ratio of the nitrogen

source to the carbon source is 0.16 wt/wt. Later the fermentation process is carried out

based on the kinetic expressions reported by Shahrokv Shahhosseini (2004) [90], using R.

eutropha at 30ºC. Afterwards, cell biomass is separated from the culture broth by a simple

gravitational sedimentation technology. After the fermentation stage, the culture broth is

Chapter 2 67

washed in order to remove impurities to finally remove water by evaporation and spray

drying to obtain PHB approximately at 98% (w/w).

Environmental Assessment

2.8.2 Environmental Assessment

The environmental analysis was carried out using the Waste Reduction Algorithm (WAR

Algorithm) designed by the Environmental Protection Agency of the United States (US EPA)

by WARGUI software. This algorithm is based on the determination of the Potential

Environmental Impact (PEI), which is a conceptual quantity representing the average

unrealized effect or impact that mass and energy emissions would have on the environment

[108]–[110] The PEI are quantified in Human Toxicity Potential by Ingestion (HTPI), Human

Toxicity Potential by Exposure (HTPE), Aquatic Toxicity Potential (ATP), Terrestrial Toxicity

Potential (TTP), Global Warming Potential (GWP), Ozone Depletion Potential (ODP),

Photo-chemical Oxidation Potential (PCOP) and Acidification Potential (AP). Some PEI’s

of compounds such as lignin, cellulose and hemicelluloses are not in database of WARGUI

software, so they were taken from several material safety data sheet, articles, among

others. The WAR algorithm is a tool to compare process configurations from the

environmental point of view.

3. Characterization results of lignocellulosic biomass

3.1 Overview

Lignocellulosic biomass consists of mainly three different types of polymers, cellulose,

hemicellulose and lignin. This chapter presents the physicochemical characterization of the

lignocellulosic biomass studied in this work as potential feedstock to produce furan-based

compounds and biofuels. In addition, the characterization provides potential information

that can be used to produce sugars (C5 and C6) in Colombia. All characterizations were

compared with previously works reported in the literature.

3.2 Results and discussion experimental characterization

Lignocellulosic biomass, mainly composed of cellulose, hemicellulose, and lignin, is the

most abundant renewable resource available for the industrial production of biochemicals.

The composition in term of major compounds is different for various plant fractions and

development stages, as well as for different types of plant cell wall. The bioconversion of

lignocellulosic materials is dependent not only on the biochemical composition of the matrix

but also on the tissues and cell wall organization and of their constituents and the interaction

between them. Thus, the information about the composition is of vital importance to

understand the mechanisms of mechanical conversion and further to optimize the utilization

of lignocellulosic materials [57], [111].



The tables 3-1 and 3-2 show the experimental chemical composition of rice husk and some

data reported in the literature respectively. As can see, the compositions change slightly

according to authors, holocellulosic content is less than in other raw materials but ash

content is considerably high. This lignocellulosic residue, besides to be source of reducing

sugars is raw material to obtain silica-based products. The medium content of fiber

lignocellulosic is reflected in minor yields to sugars. These results indicate the potential of

this raw material as source of different biochemicals due to compositional diversity.

Table 3-1 Rice husk composition on a dry basis.

Feature Content (wt %)

Cellulose

Hemicellulose

Lignin

Extractives

Ash

40.70 ± 1.77

15.57 ± 0.22

26.54 ± 5.86

6.28 ± 0.89

10.91 ± 0.01

Table 3-2 RH chemical characterization reported in literature (wt %).

Cellulose Hemicellulose Lignin Ash Others Reference

34.40 24.30 29.20 15-20 N.A. [53]

40.50 13.65 17.50 21.27 N.A. [54]

63.53* 35.50 N.A. 1.58 [112]

N.A.: Non-Available *Holocellulose: cellulose + hemicellulose

3.2.2 Sugarcane Bagasse (SCB)

Experimental chemical composition of sugarcane bagasse is shown in Table 3-3. Its

considerable holocellulose content confirms the important role as pioneer raw material to

produce energy, fuels and biochemicals. The results of characterization in the feedstock

are in accordance with studies reported by authors cited as shows the table 3-4. As can be

seen, SCB has a high content of cellulose that can be used as raw material to produce

reducing sugars (glucose) hence alcohols and organic acids can be obtained. Additionally,

the relatively low lignin content associated with the fiber makes technical and economically

Chapter 3 71

feasible the recovery of almost completely the total cellulose by using a suitable

delignification process.

Table 3-3 Sugarcane bagasse composition on a dry basis.

Component Content (wt %)

Cellulose

Hemicellulose

Lignin

Extractives

Ash

46.74 ± 4.40

23.62 ± 2.10

19.71 ± 0.76

8.79 ± 2.38

1.13 ± 0.01

Table 3-4 SCB chemical characterization reported in literature (wt %).


40.6 20.9 17.4 4.0 17.1 [57]

40-45 30-35 20-30 N.A. N.A. [61]

42.2 27.6 21.6 2.84 5.63 [63]

42.3 25.1 24.7 3.5 3.7 [63]

41.2-47 25.1-26 19.5-21.7 1.4-5.4 2.3-2.9 [63]

38.0 32.0 27.0 2.3 0.7 [113]

32-45 19-24 27-32 N.A. N.A. [114]

44.94 28.24 18.93 N.A. 7.89 [115]

N.A.: Non-Available

3.2.3 Coffee Cut-Stems (CCS)

Table 3-5 shows the experimental chemical composition of coffee cut-stems. The results

indicate as the fibers that composed this residue have a mild balance in the content of

cellulose and hemicellulose that can be raw material to obtain products from xylose and

glucose equitably. Table 3-6 shows some results of compositional analysis of lignocellulosic

biomass given in the literature. As can see, the compositions change slightly according to

authors and this may be due to culture conditions, climate and/or soil characteristics. The

use of this raw material as lignocellulosic biomass is associated to some difficulties such

as storage and collecting affected mainly when the crops are at locations that are difficult

to access. These factors can compromise the availability and the price. Despite the


potential of CCS discovered in recent years, the issues mentioned above have not allowed

a constant in their use.

Table 3-5 Coffee cut-stems composition on a dry basis.


Cellulose

Hemicellulose

Lignin

Extractives

Ash

40.39 ± 2.23

34.01 ± 1.17

10.13 ± 1.29

14.18 ± 0.85

1.27 ± 0.03

Table 3-6 CCS chemical characterization reported in literature (wt %).


37.35 27.79 19.81 2.27 12.79 [112]

33.5 24.97 17.80 N.A. N.A. [116]

40-50 20-40 18-25 N.A. N.A. [116]

N.A.: Non-Available

3.2.4 Fique Bagasse (FB)

The tables 3-7 and 3-8 indicate the results of experimental chemical composition of FB and

some data reported in the literature respectively. As can be seen, this material has a high

content of extractives represented mainly in chlorophyll. However, the cellulose content is

sufficiently representative to say that this raw material can be an additional alternative to

the well-known lignocellulosic biomass to produce bioproducts. Currently, only 4% of the

plant source of this residue is being exploited and 96% remaining is represented in juice

and bagasse. The use of bagasse as raw materials to obtain added-value products can

mitigate the self-generated pollution in crop fields.

Chapter 3 73

Table 3-7 Fique bagasse composition on a dry basis.


Cellulose

Hemicellulose

Lignin

Extractives

Ash

50.79 ± 3.01

14.19 ± 1.37

12.47 ± 1.05

21.84 ± 1.98

0.69 ± 0.09

Table 3-8 FB chemical characterization reported in literature (wt %).


67-78 7-11 20-24 0.6-1 N.A. [53]

31.08 23.19 25.45 6.41 9.5 [117]

41.81 22.17 15.56 N.A N.A [118]

N.A.: Non-Available

3.3 Final remarks

This section show the results of chemical composition of lignocellulosic biomass that may

offer interesting sources to obtain energy, biofuels, biochemicals, biofertilizers, etc. The

features of biomass analyzed reflect its great potential of viability. The integrated use of

lignocellulosic biomass characterized with a process engineering concept involves

economic and environmental benefits translated in obtaining sustainable products.

Production processes from lignocellulosics can be developed in many directions and

special attention has been paid to sugar derivatives that can be used as a chemical building

block (sugars and furan-based compounds)

4. Results physicochemical properties of blends

4.1 Overview

Environmental concerns and the rising cost of crude oil have incentivized the search for

alternative aviation fuels. However, any potential alternatives must be thoroughly

characterized and tested. In this chapter, the properties of blends such as ethanol-butanol,

ethanol-octanol and ethanol-biodiesel are presented. Density, viscosity, freezing point and

heat of combustion are assessed to analyze the compatibility between blends and

conventional jet fuel (Jet A-1). Experimental results of blends are compared with properties

of jet fuel given by ASTM D1655 and DEF STAN 91-91. According to results, the blend with

the best behavior is ethanol-biodiesel (70 to 50% of ethanol) with a density of 0.82 g cm-3,

viscosity of 6.7 mm2 s-1, freezing point of -40 ºC and flash point of 56.3ºC (average values).

4.2 Results and Discussion

Table 4-1 shows some physicochemical properties of Jet A-1. These properties given a

reference point to evaluate the compatibility of blends studied with a conventional aviation

fuel.


Table 4-1 Jet A-1 aviation fuel specifications [119], [120].

Property Unit ASTM D1655 DEF STAN 91-91

Density (15ºC) g/cm3 0.775-0.84 0.775-0.84

Viscosity (-20ºC) mm2/s Max 8 Max 8

Freezing point ºC Max -40 Max -47

Flash point ºC Min 38 Min 38

The Jet A-1 standard stipulates that the density of a fuel must sit within the range 0.775–

0.840 g cm-3. The densities of ethanol-biodiesel blend follow a roughly linear trend all within

the values specified for Jet A-1. On the contrary, the blends between alcohols have a

decreasing trend with a maximum point slightly above of required values by standard. The

density of the fuel is important in the operation of aircraft required to fly long distances, or

in smaller aircraft where space is limited. In these cases the limiting factor on range is the

volume of the fuel tank rather than the maximum structural weight capacity of the airframe

[27].

According to the Jet A-1 specifications indicate that a fuel must have a viscosity of no more

than 8mm2 s-1 at -20ºC. The viscosities of blended fuels were ascertained at an of

temperature from -20ºC up to -22ºC to give a clearer indication of performance (tables 4-1,

4-2 and 4-3). Highly viscous aviation fuels lead to poor atomization and combustion,

pumping difficulties and in extreme cases the blocking of fuel injectors. All blends exhibit

good viscosity behavior with an approximately lineal increase with a reduction in ethanol

fraction. n-Octanol had the highest viscosity for two of alternative fuels tested in this

investigation, presumably due to the increased hydrogen bonding between the alcohol

groups. As such at 90 and 70% of blend levels, n-octanol lies outside of the required

specification. Similarly, the blend with 90% of n-butanol is also not suitable as an aviation

fuel. The blends with 90% of ethanol appear to be promising candidates for blending with

aviation fuel as additive. These blends have a similar viscosity, which is roughly half that of

Jet A-1 at -20ºC. If both blends are mixed with aviation fuel can reduce the viscosity of the

overall fuel, this could have potentially beneficial consequences in terms of better

atomization and pumping, while also reducing the viscosity of highly viscous aviation fuels.

In the measure of freezing point a limitation was presented that prevented to determine with

exactness this property. For this reason, in the results only is indicated if the blend at -40ºC

Chapter 4 77

no has changed of aggregate state as establishes the requirements. All blends tested had

a suitable freezing point compatible with of the Jet A-1.

The energy density of a potential fuel impacts on the range vs. payload and a high energy

density is vital in trying to maximize the passenger and cargo capacity while retaining range.

Where weight capacity is the limiting factor, as is the case with most civil aviation flights, it

is desirable to have a fuel that produces the most energy per unit mass whereas in

applications where range is to be maximized, the volumetric energy content of the fuel is

the most important parameter, and a higher volumetric energy content is desirable [27],

[121]. In this work the heat capacity is taken as reference to measure the energy transferred

of the blend when has a temperature change. In general, the high values are presented

when the blend is dominated for a component with high molecular weight.

The flash point of a fuel is the temperature at which an ignitable air/fuel vapor forms above

the fuel. Conventional aviation fuel is a complex mixture of a few hundred different

hydrocarbons and as such, the molecular interactions that may govern the temperature at

which the flash point occurs are difficult to predict [27]. In this work the flash points of all

the alternative fuels were determined experimentally (Tables 4-2 to 4.4). The flash point of

the blended fuels appears to be largely dictated by that of the lower flashpoint component.

In the case of ethanol-butanol blend, the flash point of pure components is considerably

low for this reason the blends is not according to established in the standard. For the blend

ethanol-octanol only when ethanol is present in 10% of blend the flash point is acceptable.

Finally, for the blend ethanol-biodiesel the flash point increases proportionally to increment

of biodiesel fraction.


Table 4-2 Experimental properties for the ethanol-butanol blend in mass fractions.

Ethanol

fraction

Density to

15ºC (g/cm3)

Viscosity to -

20ºC (mm2/s)

Freezing

point (ºC)

Flash

point (ºC)

Heat capacity

(J/kg K)

0.1 0.88 9.19 < to -47 30 648.58

0.3 0.87 6.29 < to -47 27 -----

0.5 0.90 5.49 < to -47 20 952.21

0.7 0.86 4.21 < to -47 17 -----

0.9 0.84 3.35 < to -47 15 649.44

Table 4-3 Experimental properties for the ethanol-octanol blend in mass fractions.

Ethanol

fraction

Density to

15ºC (g/cm3)

Viscosity to -

20ºC (mm2/s)

Freezing

point (ºC)

Flash

point (ºC)

Heat capacity

(J/kg K)

0.1 0.890 33.1 < to -47 38 1216.27

0.3 0.918 14.8 < to -47 35 -----

0.5 0.861 6.98 < to -47 34 736.11

0.7 0.864 4.84 < to -47 28 -----

0.9 0.858 4.80 < to -47 25 630.26

Table 4-4 Experimental properties for the ethanol-biodiesel blend in mass fractions.

Ethanol

fraction

Density to

15ºC (g/cm3)

Viscosity to -

20ºC (mm2/s)

Freezing

point (ºC)

Flash

point (ºC)

Heat capacity

(J/kg K)

0.9 0.725 3.79 < to -40 28 824.11

0.8 0.789 4.76 < to -40 37 -----

0.7 0.808 5.09 < to -40 47 693.18

0.6 0.817 6.65 < to -40 55 -----

0.5 0.835 8.58 < to -40 67 521.75

4.3 Final remarks

According to the results from physicochemical properties in biofuel blends can be found an

alternative additive for the oxygenation of conventional fuels. While jet fuels have

requirements for the properties to low temperatures, the blend of ethanol-biodiesel satisfies

Chapter 4 79

substantially these requests. The use of these blends as additive or biofuel from process

generally biological can help to decrease the emissions of pollutants linked to the fossil

fuels and promote the transformation and use of lignocellulosic biomass. From global point

of view the use of biofuels in aviation can present some problems such as engine

modifications, thermal stability of fuel, storage of raw materials and biofuels, and production

costs and cost effectiveness of the process related to production.

5. Experimental results for production of ethanol and furfural from lignocellulosic biomass

5.1 Overview

In this chapter, the results of the experimental evaluation to obtain ethanol, furfural and

alkane precursors through two conditions of acid hydrolysis from rice husk, sugarcane

bagasse, coffee cut-stems and fique bagasse are presented. First, the influence of

pretreatment conditions such as time and acid concentration in the yields of sugars, ethanol

and furan-based compounds are analyzed. Besides, the profiles of the ethanolic

fermentation are shown. Second, the yields obtained in each one of stages of

transformation process are discussed which are composed of steps shown in the figure 4-

1. Finally, the characterization of catalyst used in aldolcondensation reaction to obtain jet

fuel intermediates is presented. This process is made by a wide range of physical

techniques such as X-ray, FT-IR, TGA and SEM-EDX.

5.2 Results and discussion of experimental procedure

Figure 5-1 shows the schematic representation of the sequence established for the

processing of the agroindustrial wastes to obtain ethanol, furan-based compounds and

alkane precursor. Pretreatment initial of raw materials is surely a key element regarding

technical and economical features. This stage comprises material adequacy (drying and

particle size), acid hydrolysis and enzymatic hydrolysis. These procedures are made in


order to alter the lignocellulosic structure of feedstock and obtain sugars (xylose and

glucose) as platform to transform to interesting products.

Figure 5-1 Diagram of experimental procedure to obtain ethanol, furfural and alkane precursor.

Cond 1. 2 %v/vH2SO4, 5h y 115ºC. Cond 2. 10 %v/vH2SO4, 0.5h y 115ºC

Tables 5-1 to 5-4 indicate the results obtained in experimental procedure of conversion of

lignocellulosic biomass studied in this work to alcohol, furan-based compound and

derivatives. First, the concentrations of glucose, xylose, furfural and HMF obtained at two

operation conditions of acid hydrolysis. Second, the amount of reducing sugars generated

in cellulose transformation through of enzymatic hydrolysis. Third, the yield referred to the

mass of ethanol per mass of substrate in process fermentation. Fourth, data of dehydration

reaction as the final concentration of furfural with his respective yield per mass of xylose.

Finally, furfural consumption to produce alkane precursor in aldol condensation reaction.

Chapter 5 83

5.2.1 Ethanol production

Ethanol is a liquid biofuel with the potential to partially replace the gasoline needed for

transportation worldwide and in the last years this fuel has become one of the most studied

biofuels. It is well known that ethanol production from lignocellulosic biomass involves four

steps: mechanic pretreatment of biomass, saccharification (acid and/or enzymatic),

fermentation and distillation. Then, a brief discussion of results obtained for the first three

stages corresponding to the work developed in this thesis.

The acid hydrolysis has variables as reaction time and acid concentration that determine

the formation of products. For this reason, two operation conditions were evaluated.

According with the results for RH and SCB, the reaction time has an effect positive in

production of xylose and acid concentration helps to have higher concentration of furfural

as by-product. However, this parameters have different effect when it is CCS and FB. In

these cases, the sugar and furfural concentration has not a significant change between

hydrolysis conditions. In this sense, acid hydrolysis with operation conditions 1 are obtained

yields for xylose of 0.83, 0.81, 0.50 and 0.58 grams per grams of hemicellulose contained

in RH, SCB, CCS and FB respectively. For operation conditions 2 are obtained yields for

xylose of 0.61, 0.60, 0.51 and 0.54 grams per grams of hemicellulose for RH, SCB, CCS

and FB respectively.

When acid hydrolysis is carried out using a high concentration of acid can bring serious

implications on sugar integrity affecting the yields of reducing sugars in enzymatic

hydrolysis. Results show that for operation conditions 1 there are yields of 0.20, 0.38, 0.21

and 0.34 (grams of glucose per gram of initial cellulose) for RH, SCB, CCS and FB

respectively. On the contrary, for conditions 2 the yield for RH, SCB, CCS and FB were

0.17, 0.33, 0.19, and 0.33 respectively. Due to that the hydrolysis with 10% of H2SO4 has

not a large contact time, the yields show no a considerable reduction. Raw materials that

have high cellulose content offer high concentration of sugars reducing, it is the case of

SCB and FB.

Process fermentation is the final stage for glucose line, the availability of sugars reducing

determines the productivity in the transformation to ethanol. The conversion of sugars from

lignocellulosic biomass studied in this work indicate satisfactory results but, as was

expected the yields in conditions 1 show higher values. Data reported in literature indicate

that yields when CCS is used as raw material are 0.34, 0.23 and 0.41 grams of ethanol per


gram of substrate (xylose and glucose) for Candida lusitaniae, Pichia stipitis and

Zymomonas mobilis as microorganisms respectively [52], [65]. If rice husk is used as raw

material can be obtained yields of 0.29 grams of ethanol per gram of reducing sugars using

Saccharomyces cerevisiae as microorganism [52]. In the case of sugarcane bagasse using

S. cerevisiae the yield is 0.42 grams of ethanol per gram of sugars [122].

In the comparison of yields obtained with data reported can be seen that the experimental

procedures made in this work have a remarkable approach with what says the literature

using S. cerevisiae as microorganism and RH as raw material. For SCB, being the results

obtained considerably good the studies report slightly higher values. In the case of CCS,

although only glucose is considered as carbon source the yields obtained are high

compared with fermentation using P. stipitis and glucose and xylose as microorganism and

raw material respectively, as shown above. Finally, when FB is used the results are

satisfactory irrespective of little use that this feedstock has as source of ethanol.

5.2.2 Furfural production

Furfural is considered a chemical platform highly versatile and key used in the manufacture

of a wide range of important chemicals, and it is likely to be of increasing demand in different

fields, such as plastics, pharmaceutical, energy and agrochemical industries [73]–[75], [91],

[123]. C. Rong et al. 2012 reported that the production of furfural from corn stover has a

yield of 75% using as catalyst 10 %w/w of sulfuric acid. Additionally indicates that xylose

dehydration to furfural, the yield was under 10% when acid was nearly to 2.5% w/w. But

when the concentration of sulfuric acid became 12.5% w/w, the yield reduce to 51% [75].

In this work the acid concentrations were 3 and 18% w/w for operation condition 1 and 2

respectively. As can be seen, for all raw materials studied and subject to conditions 1 and

2 the average yields were 0.08 and 0.085 grams of furfural per gram of xylose respectively.

These results show a concordance slightly significant with the reported. The low yields of

furfural can be attributed to side reactions, such as xylose dehydration to other aldehydes

(e.g., formaldehyde), degradation of furfural, or polymerizations of intermediate, and furfural

[75].

Chapter 5 85

5.2.3 Catalyst characterization

X-Ray diffraction analysis

Figure 5-2 shows X-ray diffraction patterns of Mg-OX and ZrO2 and figure 5-3 shows X-ray

spectrum of MgO-ZrO2 obtained in catalyst characterization. In the comparison of both

figures can see that the X-ray pattern shows the presence of bands corresponding to MgO

(periclase) and ZrO2 (tetragonal phase) in the sample.

Figure 5-2 X-ray diffraction pattern of Mg-OX and ZrO2 [76].

Figure 5-3 X-ray spectrum of MgO-ZrO2 obtained in catalyst characterization.

FT-IR spectrum of MgO-ZrO2

Figure 5-4 shows FT-IR spectrum of MgO-ZrO2. The Fourier transform infrared spectrum

(FT-IR) of MgO–ZrO2 shows a strong absorption at 427.3 cm-1 due to the Zr–O vibration.


The intense bands were observed at 3405.2 and 1444.2 cm-1, it could be due to hydrated

compounds [81], [124]. The FT-IR spectrum of MgO–ZrO2 in the n(OH) region shows one

slight band around 3600–3700 cm-1, this band corresponds to –OH stretching vibrations of

surface hydroxyl groups [81], [125]. The peak observed at 1444.2 cm-1 could be due to Mg–

O interaction [81], [126].

Figure 5-4 FT-IR spectrum of MgO-ZrO2.

TGA profile of MgO-ZrO2

The thermal stability of the prepared sample was investigated by a TGA method. The

thermogram obtained for the calcined MgO–ZrO2 is presented in Figure 5-5. The TG profile

was characterized by two peaks of weight loss till 411.9ºC. The first one occurs at 38.65ºC

to 186.12ºC (3.34% weight loss). The second weight loss occurred between (4.66% weight

loss) 186.12ºC and 411.9ºC.

Figure 5-5 TGA profile of MgO-ZrO2.

Chapter 5 87

SEM-EDS Analysis

SEM images are shown in Figure 5-6 for catalyst. The EDX spectrum of catalyst clearly

indicates presence of Pd, Mg and Zr. From figure 5-6, it is evident that Pd/MgO-ZrO2

particles were obtained in a micro size range and showed uniform-sized particles.

Figure 5-6 SEM image of catalyst at 10μm. EDX spectrum and compositional report of catalyst.

Element Wt% At%

CK 669 1120 OK 3648 4583 MgK 5037 4164 ZrL 365 80 PdL 281 53

5.2.4 Alkane precursor production

MgO-ZrO2 is considered a heterogeneous catalyst and is composed by mixed metal oxides

(MMOs). MMOs can offer a modulation of surface acidity, catalytic activity and thermal

stability that leading to higher application in different fields compared to pure oxides. MMOs


represent one of the most important and widely employed classes of solid catalyst, either

as active phases or supports [76]. These catalyst are applied both for their acid-base and

redox properties. Important organic reactions as aldol-condensation, Cbz-protection of

amines and synthesis of 1,5-benzodiazepine are carried out in presence of this catalyst

[81].

Aldol-condensation and hydrogenation steps to form C8 to C15 alkane precursors is carried

out using a bifunctional Pd/MgO-ZrO2 catalyst that according to W. Shen et al., 2011 [77]

and C. J. Barret et al., 2006 [39] has high activity and selectivity, as well as excellent

recyclability and hydrothermal stability. It is important to note that during first reaction the

Pd on the catalyst is inert, because the performance of the Pd/MgO-ZrO2 catalyst is

identical to the performance of MgO-ZrO2 during aldol-condensation. The large compounds

obtained from this series of reactions undergo hydrodeoxygenation reactions to produce

final alkanes [39] - [41], [77]. Figure 5-7 indicates the essential features of the bifunctional

reaction pathways involved in the production of intermediates jet fuel (C8 to C15 alkane

precursors) from biomass-derived furfural from xylose.

Figure 5-7 Aldol-condensation reaction of furfural and acetone, followed by hydrogenation of aldol

products [39], [40].

Figures 5-8 to 5-11 show the appearance of precursor (4-(2-furyl)-3-buten-2-one) after

aldol-condensation reaction for operation condition 1 in acid hydrolysis of each raw

material. This product is the main intermediate or precursor to obtain jet fuels. The catalytic

performance was evaluated by the disappearance of furfural and appearance of monomer

despite that is not possible quantify the amount produced. According to results, specifically

the percentage of disappearance of furfural that indicate the tables 5-1 to 5-4 the Pd/MgO-

Chapter 5 89

ZrO2 as catalyst exhibits excellent catalytic activity with a maximum furfural conversion of

96.5% after reaction for 24h at 120ºC in a batch reactor.

When aldol-condensation reaction is carried out for operation condition 2, the formation of

interest product is not recorded for all raw materials. Taking into account that in this case

the reaction was evaluated according to following conditions, i) excess of catalyst, ii) excess

of acetone, iii) normal load of catalyst and iv) lower than normal catalyst loading. Although

were made some testing is believed that the high concentration of homogenous catalyst

(H2SO4) used in acid hydrolysis and dehydration inhibited to the heterogeneous catalyst

(Pd/MgO-ZrO2) or have been encouraged unwanted reactions forming sulfates of

magnesium, palladium and/or zirconium.

The data reported in literature indicate a disappearance percentage of 66% in the same

conditions that the procedure developed in this work [77]. When compared to results

obtained it is possible to say that the experiments made in this work are excellent and

shown clearly the potential of furfural as platform product to obtain great amount of

chemicals.

Figure 5-8 GC-MS chromatographs of furfural and precursor when RH is the used as raw material.


Figure 5-9 GC-MS chromatographs of furfural and precursor when SCB is the used as raw material.

Figure 5-10 GC-MS chromatographs of furfural and precursor when CCS is the used as raw

material.

Figure 5-11 GC-MS chromatographs of furfural and precursor when FB is the used as raw material.

Chapter 5 91

Table 5-1 Results ethanol and furfural production from RH.

Dilute-acid hydrolysis

Condition Temperature (ºC) Reaction time (h) H2SO4 (%v/v) Glucose (g/L) Xylose (g/L) Furfural (g/L) HMF (g/L)

1 115 5 2 2.64±0.02 14.76±0.42 1.09±0.02 0.05±0.0

2 115 0.5 10 4.01±0.15 10.84±0.28 1.74±0.02 0.04±0.0

Enzymatic hydrolysis

Acid Hydrolysis Condition Reducing sugars (g/L)

1 9.43±0.55

2 8.31±0.25

Ethanolic fermentation

Acid Hydrolysis Condition Yield (g ethanol/g glucose)

1 0.26±0.02

2 0.20±0.01

Dehydration reaction

Acid Hydrolysis Condition Furfural (g/L) Yield (g furfural/g xylose)

1 3.03±0.06 0.13±0.005

2 3.59±0.05 0.17±0.02

Aldol-condensation reaction

Acid Hydrolysis Condition Furfural (g/L) % disappearance

1 1.25±0.08 58.7±0.02


Table 5-2 Results ethanol and furfural production from SCB.



1 115 5 2 5.75±0.11 22.10±0.05 1.48±0.01 0.09±0.0

2 115 0.5 10 7.03±0.26 16.21±0.16 1.89±0.15 0.05±0.0



1 20.65±1.77

2 18.12±0.83


Acid Hydrolysis Condition Yield (g ethanol/g substrate)

1 0.27±0.005

2 0.24±0.013



1 2.83±0.06 0.06±0.008

2 2.85±0.05 0.06±0.057



1 0.80±0.12 71.7±0.018

Chapter 5 93

Table 5-3 Results ethanol and furfural production from CCS.



1 115 5 2 2.89±0.08 19.41±0.61 0.92±0.05 0.07±0.0

2 115 0.5 10 3.07±0.15 19.58±0.02 0.86±0.05 0.05±0.0



1 9.66±0.40

2 8.83±0.10



1 0.25±0.06

2 0.19±0.003



1 2.16±0.21 0.063±0.02

2 2.17±0.15 0.067±0.005



1 0.074±0.02 96.5±0.014


Table 5-4 Results ethanol and furfural production from FB.



1 115 5 2 9.14±0.21 9.34±0.13 0.30±0.02 0.51±0.01

2 115 0.5 10 9.14±0.21 8.55±0.21 0.27±0.01 0.21±0.01



1 19.69±1.25

2 18.69±1.55



1 0.24±0.03

2 0.23±0.02



1 1.16±0.08 0.092±0.009

2 0.66±0.09 0.045±0.052



1 0.082±0.04 92.9±0.008

5.3 Final remarks

In this study the performance and influence of the operating conditions for acid hydrolysis

on processes RH, SCB, CCS and FB were compared. The overall data presented here

increase the understanding of the effects of acid concentration on raw materials when

are submitted to the enzymatic hydrolysis and fermentation process to obtain ethanol,

dehydration to produce furfural and aldol-condensation to generate monomer. Besides

knowing the excellent features that have the lignocellulosic biomass as availability and

low commercial value to produce biofuels as ethanol this work presents a new

perspective for biomass conversion from catalysis point of view to obtain precursors of

jet fuel range alkanes.

Also, has been shown that Pd/MgO-ZrO2 catalyst prepared by a simple and green

method exhibits excellent performance and is an active catalyst for aldol-condensation

over basic sites (MgO-ZrO2). This bifunctional catalyst allows to carbohydrate-derived

compounds, like furfural and HMF, to be converted in a single reactor to large water-

soluble intermediates for further aqueous phase processing to produce liquid alkanes.

6. Techno-economic and environmental assessment for jet biofuels production

The raw materials assessed can be used to obtain not only jet fuel additives, but also to

generate other products of added-value as demonstrated in Chapter 5. In this chapter

different cases are presented including biorefineries and no biorefineries approaches.

6.1 Biorefineries based on coffee cut-stems and sugarcane bagasse: furan-based compounds and alkanes as interesting products

6.1.1 Overview

This work presents a techno-economic and environmental assessment for a biorefinery

based on sugarcane bagasse and coffee cut-stems. Five scenarios were evaluated at

different levels, conversion pathways, feedstock distribution and technologies to produce

ethanol, octane, nonane, furfural and hydroxymethyl furfural (HMF). These scenarios

were compared between them according to raw material and economic and

environmental characteristics. A simulation procedure was used in order to evaluate

biorefinery schemes for all the scenarios, using Aspen Plus software. The results showed

that the configuration with the best economic and environmental performance for

sugarcane bagasse and coffee cut-stems is the one that considers ethanol, furfural and

octane production (scenario 1). The global economic margin was 62.3% and 61.6% for

SCB and CCS respectively. The results have shown the potential of these types of

biomass to produce fuels and building block products (furfural). The environmental

assessment revealed that the scenario that considers the production of ethanol and

octane (scenario 1) was the most environmentally friendly given their lower consumption

of chemical reagents. In contrast, the scenario that considers the production of furfural


and HMF (scenario 5) had a major potential environmental impact due to the use of large

volume of solvents and toxicity of furan-based compounds.

6.1.2 Biorefineries from sugarcane bagasse and coffee cut-stems

According to International Energy Agency (IEA) Bioenergy Task 42 a biorefinery is

defined as “A sustainable processing of biomass into a spectrum of marketable products

and energy” [127], [128]. A biorefinery is a network of facilities that integrates biomass

conversion processes and equipments to produce biofuels, power and chemicals from

biomass. This concept is analogous to today's petroleum refinery, which produces

multiple fuels and chemicals from petroleum [127], [128]. A biorefinery can take

advantage of the different biomass constituents and intermediates and maximize the

value derived from the feedstock. In this respect, the most effective and efficient

utilization of renewable biomass resources is through the development of an integrated

biorefinery. Through this strategy the processes included on biorefinery concept can be

economically profitable and environmentally sustainable.

Second generation raw materials (lignocellulosic biomass) are generally considered a

promising feedstock due to its availability in large quantities, its relatively low cost and

its potential sustainability [52], [92], [112]. Sugarcane bagasse is a fibrous residue

obtained after extracting the juice from sugarcane in the sugar production process.

Coffee cut-stems is a cut above the land where the coffee plant is cultivated of 15-20 cm

of length and is obtained by crop renewal. These lignocellulosic wastes are found

especially in tropical countries as Colombia, Brazil, Cuba and Indonesia [52], [65]. In

Colombia, around 5 and 7 million tons of sugarcane bagasse and coffee cut-stems

respectively were generated at 2014 [47], [49]. While, the comparison between these

raw materials is made because if SCB is a well-known lignocellulosic biomass, instead

CCS is born as an alternative that can be as competitive as the aforementioned.

Ethanol is highly commercial and is used as a large-scale transportation fuel.

Hemicellulose present in biomass undergoes an acid hydrolysis to form xylose, and then

xylose is dehydrated to form furfural. Furan-based compounds are a highly versatile and

key derivatives used in the manufacture of a wide range of important chemicals and can

serve as precursors for production of jet fuels substitutes or additives (alkanes C7-C15)

[41], [129].

Chapter 6 98

Several pathways for conversion of furan-based compounds are considered in Figures

6-1 and 6-2 [34]. Biomass-derived sugars can be upgraded to conventional fuels through

the combination of aldol-condensation reactions and hydrogenation/dehydration

reactions. Dumesic et al. [39], [40], [105], [129] have done intense work in this area,

applying molecular engineering concepts to formulate catalytic strategies and

transformation routes of biomass for the production of renewable fuel components and

chemicals. Considering the rapid progress on the catalytic conversion of biomass, this

work concentrates mainly on describing of a feasibility study through simulation

strategies.

In this section, two lignocellulosic materials were considered in order to evaluate the

viability of the production of ethanol, furfural and HMF (furan-based compounds), octane

and nonane (alkanes) over biorefinery concept. These consist in sugarcane bagasse

(SCB) and coffee cut-stems (CCS). The five evaluated scenarios were as follows: i)

production of ethanol from hexoses and octane, ii) production of ethanol, octane and

nonane, iii) production of same products of scenario ii but ethanol and nonane from 40%

and 60% of glucose respectively, iv) production of ethanol from pentoses and nonane,

and v) production of furfural and HMF. The comparison of the evaluated scenarios was

performed using modern process-engineering tools. Each scenario was evaluated from

a technical, economic and environmental point of view. The chemical composition of

SCB and CCS was determined experimentally. The chemical composition of raw

materials was also used as the starting point in the processes simulation.

Figure 6-1 Catalytic pathways for furfural conversion.


Figure 6-2 Catalytic pathways for HMF conversion.

6.1.3 Scenarios and process description

For the evaluation of the biorefineries from SCB and CCS five scenarios were included

per each raw material. The scenarios consider integrated production of ethanol, octane

and nonane as main products and building block products as furfural and HMF (furan

compounds). For all scenarios, the feedstock was 5 tons/h (equivalent to 40,000

tons/year). This feedstock value is a minimum amount that represents approximately

0.05 % of biomass in the country for 2014 [49], [93]. The raw materials composition was

shown in the chapter 3.

The scenarios are based on distributions and technologies for the same amount of SCB

and CCS as feedstock. In this way, a description of biorefineries from SCB and CCS

included in this study is shown in Table 6-1. This description indicates the distribution of

materials across the processes and also technologies for each product. The aim of the

evaluation of the five scenarios from two raw materials is basically done in order to

compare each other in terms of performance from the techno-economic and

environmental point of view. This comparison is the basis to decide which could be the

best alternative for biorefinery configuration according to raw material. Figure 6-3 shows

four technological scenarios corresponding to the distribution of raw material and the

products formation (scenarios 1, 2, 4 and 5). The description of production processes to

obtain sugars, ethanol, furfural, HMF, octane and nonane are shown above in the section

2.8.1.

Chapter 6 100

Figure 6-3 Technological scenarios corresponding to the distribution shown in the scenarios

description.


Figure 6-3 (Continued).

Chapter 6 102

Table 6-1 Scenarios description in biorefineries from SCB and CCS.

Scenario Products

Technology Distribution Top Secondary

Sc. 1 Ethanol

Octane Furfural

Hemicellulose hydrolysis Sulfuric acid 2% v/v.

Cellulose hydrolysis Enzymatic hydrolysis.

Ethanol production Continuous Bioreactor.

Saccharomyces Cerevisiae.

Furfural production Xylose dehydration

Octane production

Aldolcondensation with acetone.

Hydrogenation. Dehydration/Hydrogenation.

Ethanol production

100% of glucose from cellulose.

Furfural production

100% of xylose from hemicellulose.

Octane production

100% of furfural from xylose.

Sc. 2

Ethanol

Octane

Nonane

Furfural

HMF




Saccharomyces Cerevisiae

Furfural production Xylose dehydration.

Octane production Aldolcondensation with acetone.

Hydrogenation. Dehydration/Hydrogenation.

HMF production Glucose dehydration.

Nonane production Aldolcondensation with acetone.

Hydrogenation. Dehydrogenation/hydrogenation.

Ethanol production


Furfural production

100% of xylose from hemicellulose.

HMF production


Octane production


Nonane production

100% of HMF from glucose.


Table 6-1 (Continued)

Scenario Products


Sc. 3

Ethanol

Octane

Nonane

Furfural

HMF





Furfural production Xylose dehydration.

Octane production

Aldolcondensation with acetone. Hydrogenation.

Dehydration/Hydrogenation.




Ethanol production

40% of glucose from cellulose

Furfural production

100% of xylose from

hemicellulose.

HMF production


Octane production


Nonane production


Sc. 4 Ethanol

Nonane HMF




Zymomonas mobilis




Ethanol production 100% of

xylose from hemicellulose.

HMF production 100% of glucose

from cellulose.

Nonane production 100% of

HMF from glucose.

Chapter 6 104

Table 6-1 (Continued)

Scenario Products


Sc. 5 Furfural

HMF



Furfural production Xylose dehydration. Liquid-liquid

extraction with toluene and distillation.

HMF production Glucose dehydration. Liquid-liquid

extraction with DMSO and distillation.

Furfural production

100% of xylose from

hemicellulose.

HMF production



6.1.4 Results and Discussion

Simulation results for ethanol, liquid alkanes and furan compounds production from SCB

and CCS are shown in Table 6-2. Higher cellulose content in SCB has allowed to obtain a

higher sugars yield and consequently a higher ethanol, HMF and nonane yield than in the

case of CCS. On the contrary, CCS present higher hemicellulose content and hence a

higher furfural and octane production. The overall yields according to kinetics studied for

conversion of lignocellulosic material to sugars were 0.71 grams of xylose per grams of

hemicellulose and 0.64 grams of glucose per grams of cellulose. In the case of ethanol

production, the yields obtained were 0.54 grams per grams of glucose and 0.45 grams per

grams of xylose.

Table 6-2 Production capacities of top and secondary products per scenario.

Scenario Raw

material

Ethanol

(kg/h)

Octane

(kg/h)

Nonane

(kg/h)

Furfural

(kg/h)

HMF

(kg/h)

Sc. 1 SCB 786.08 644.18 ----- 681.52 -----

CCS 664.79 925.65 ----- 979.30 -----

Sc. 2 SCB 471.27 644.18 265.95 681.52 398.18

CCS 406.01 925.65 232.03 979.30 347.58

Sc. 3 SCB 310.24 644.18 398.85 681.52 597.27

CCS 270.66 925.65 339.74 979.30 521.38

Sc. 4 SCB 366.01 ----- 664.66 ----- 995.45

CCS 527.99 ----- 549.17 ----- 868.97

Sc. 5 SCB ----- ----- ----- 674.00 1048.0

CCS ----- ----- ----- 703.37 863.06

Economic assessment

According to the results obtained from Aspen Process Economic Analyzer package

adapted to Colombian parameters, the feature that contributes with a higher proportion on

the total production costs are operating costs that includes various aspects inherent to the

production process such as raw materials, utilities, labor and maintenance, general plant

costs and general administrative costs. For most industrial processes the raw materials

represent approximately more than 50% of total production cost.

Chapter 6 106

Distribution and technologies included in the chosen products directly affect yields and the

production costs. Table 6-3 shows production costs of products in each scenario depending

of raw material. Higher cellulose content in SCB is translated in economic terms to a low

cost of ethanol, HMF and Nonane compared with CCS as raw material. Thus, considerable

content of hemicellulose in CCS reflects in low production costs of furfural and octane.

When all glucose is destined to produce ethanol (scenario 1) from SCB and CCS the

economic margins are 61.6% and 51.4%, respectively. If the xylose is the substrate to

ferment (scenario 4) the economic margins are -71.03% and -22.43% for SCB and CCS,

respectively. This difference could be explained by the dependence of the product to the

amount of substrate available and yields in pretreatment (acid hydrolysis) and enzymatic

hydrolysis. In the scenarios 1, 2 and 3 both the building block product (furfural) and the

octane have good profitability with an average economic margin of 75% and 62.7%

respectively. In the same way, the scenarios 2, 3 and 4 have positive economic margin for

HMF and nonane of around 81.5% and 36.3% respectively. In these scenarios there is a

difference in distribution of raw material (cellulose) equivalent to 4.5% of the economic

margin. The scenario 5 shows the production of furfural and HMF following by stages of

pretreatment of raw material, reaction and separation that in others scenarios the process

arrives only to reaction stage. In the case of SCB, this implies an increase in the production

cost of 0.44 and 0.6 USD/kg of furfural and HMF respectively and for CCS the increase is

0.47 and 0.59USD/kg for furfural and HMF respectively.

Figure 6-4 shows the global economic margins for all scenarios evaluated from SCB and

CCS. According to these results, the scenario 1 to SCB and CCS, have the highest

economic margin consequently the best profitability followed by the scenario that considers

the production of furfural and HMF (scenario 5). The results have shown the potential of

these types of biomass to produce fuels and building block products (furfural and HMF).


Table 6-3 Production cost of biorefinery products from SCB and CCS.

Item Sc. 1 Sc. 2 Sc. 3 Sc. 4 Sc. 5

Total production cost Ethanol (USD/kg)

SCB 0.41 0.58 0.84 1.83 -----

CCS 0.52 0.68 0.84 1.31 -----

Total production cost Octane (USD/kg)

SCB 2.63 2.63 2.63 ----- -----

CCS 2.58 2.58 2.58 ----- -----

Total production cost Nonane (USD/kg)

SCB ----- 10.46 10.27 10.22 -----

CCS ----- 10.80 10.51 10.24 -----

Total production cost Furfural (USD/kg)

SCB 0.47 0.47 0.47 ----- 0.91

CCS 0.38 0.38 0.38 ----- 0.85

Total production cost HMF (USD/kg)

SCB ----- 0.40 0.35 0.32 0.94

CCS ----- 0.47 0.39 0.37 0.96

Figure 6-4 Global economic margins for all scenarios evaluated from SCB and CCS.

Environmental assessment

The results of the potential environmental impact per kilogram of products are presented in

Table 6-4 and Figure 6-5. The results showed that for all the evaluated scenarios, the

impacts that contribute the most to the PEI were photochemical oxidation potential (PCOP)

Sc 1 Sc 2 Sc 3 Sc 4 Sc 5

SCB 62.33 43.79 43.50 30.43 50.00

CCS 61.59 54.01 54.43 51.00 51.08

0.00

10.00

20.00

30.00

40.00

50.00

60.00

70.00

Econom

ic M

arg

in (

%)

SCB CCS

Chapter 6 108

due to organic load of effluents as vinasse and solvent purge and gas emission. Besides

Human toxicity potential by ingestion (HTPI) and terrestrial toxicity potential (TTP), that are

highly related because both are calculated in function of lethal dose by ingestion (LD50).

Chemical reagents involved on processes are direct contributors to these categories.

Table 6-4 Potential environmental impact for the different scenarios according to raw material.

Human toxicity by ingestion (HTPI), human toxicity by dermal exposition or inhalation (HTPE),

terrestrial toxicity potential (TTP), aquatic toxicity potential (ATP), global warming (GWP), ozone

depletion potential (ODP), photochemical oxidation potential (PCOP), and acidification potential

(AP).

Scenario Raw

materials

Impacts

HTPI HTPE TTP ATP GWP ODP PCOP AP

Sc. 1 SCB 2.53e-1 1.52e-1 2.53e-1 1.16e-2 6.02e-3 2.24e-8 5.81e-1 6.13e-2

CCS 5.16e-1 1.33e-1 5.16e-1 1.54e-2 5.95e-3 2.23e-8 8.37e-1 6.09e-2

Sc. 2 SCB 4.79e-1 1.28e-1 4.79e-1 1.30e-2 4.92e-3 1.84e-8 7.65e-1 5.02e-2

CCS 5.19e-1 1.24e-1 5.19e-1 1.44e-2 5.54e-3 2.07e-8 8.82e-1 5.67e-2

Sc. 3 SCB 2.59e-1 1.20e-1 2.59e-1 1.15e-2 4.73e-3 1.77e-8 5.60e-1 4.84e-2

CCS 5.20e-1 1.20e-1 5.20e-1 1.61e-2 5.37e-3 2.02e-8 8.65e-1 5.51e-2

Sc. 4 SCB 4.38e-1 7.91e-2 4.38e-1 8.77e-3 3.48e-3 1.19e-8 4.56e-1 3.24e-2

CCS 6.65e-1 5.42e-2 6.65e-1 1.87e-2 9.01e-3 3.30e-8 6.97e-1 9.02e-2

Sc. 5 SCB 6.14e-1 1.42e-1 6.14e-1 1.03e-2 1.92e-3 7.30e-9 9.22e-1 1.99e-2

CCS 7.17e-1 1.63e-1 7.17e-1 1.65e-2 8.39e-3 3.18e-8 1.16 8.70e-2

From the raw material point of view, the first scenario was the most environmentally friendly

given their lower consumption of chemical reagents. In contrast, the fifth scenario had a

major potential environmental impact due to the use of large volume of solvents and toxicity

of furan compounds.


Figure 6-5 Total potential environmental impact for the different scenarios according to raw

material.

6.1.5 Conclusions

According to the techno-economic results, CCS is a lignocellulosic raw material that if it is

not well known have a potential and can be as competitive as sugarcane bagasse. As a

general conclusion, this work demonstrated that it is technically possible to convert SCB

and CCS to produce ethanol, jet fuels range alkanes and furan-based compounds under a

biorefinery scheme. These compounds show interesting properties and are precursors for

the synthesis of products in the same way as the sugars (C5-C6).

0.00E+00

1.00E+00

2.00E+00

3.00E+00

4.00E+00

Sc 1 Sc 2 Sc 3 Sc 4 Sc 5

To

tal (P

EI/k

g P

rod

uc

t)

SCB CCS

Chapter 6 110

6.2 Design and analysis of process schemes based on coffee cut-stems coupled with gasification technology

6.2.1 Overview

In this section, a techno-economic assessment for process schemes to obtain alcohol and

alkane from coffee cut-stems are presented. Four scenarios were evaluated at different

levels for ethanol, furfural and octane production. These scenarios were compared between

them according to use of cogeneration system and economic behavior. A simulation

procedure was used in order to evaluate process schemes for all the scenarios, using

Aspen Plus software. The results showed that the configurations with the best economic

performance are the one that consider the cogeneration system (scenarios 3 and 4). The

global economic margin for scenarios 1 and 2 was 38.4% and 62.7% respectively. For

scenarios 3 and 4 was 46.3% and 64.1% respectively. The results shown the positive

impact in economic terms that can have a cogeneration system on a process scheme to

obtain fuel and biochemicals from CCS.

6.2.2 Production of ethanol and octane from lignocellulosic biomass

The uncertainty on oil reserves, oil prices as well as the climate change have become in

important reasons to search new alternatives to produce valuable chemicals and fuels

[130], [131]. In this sense, biomass appears as a source to produce environmentally friendly

biofuels and biobased materials with promising substitution capacity of petrochemical

sources. Renewable biomass resources are considered promising and particularly

attractive, and worldwide many efforts have been devoted to its conversion [34], [36], [37],

[41]. Especially, the derivation of biofuel from the catalytic conversion of lignocellulosic

biomass has become one of the trendiest research subjects in the world.

Bioethanol is one biofuel well known for its competition commercial, calorific properties and

sustainable production. Recently, studies report that jet fuels range alkanes could be

obtained from lignocellulosic biomass by a novel route, wherein C5 sugar was firstly

produced by hydrolysis of biomass and then converted into furfural by a dehydration step;

furfural was further reacted with acetone by an aldol condensation step to produce jet fuel


intermediates, following by the generation of long chain alkanes ranging from C7 to C15 via

a dehydration/hydrogenation step. Furfural offers an important and rich source of

derivatives that have potential use as biofuel components [35]–[37].

In this section, CCS as lignocellulosic material was considered in order to evaluate the

viability of the production of ethanol, furfural and octane. The following four scenarios were

evaluated: i) production of ethanol from hexoses and furfural from pentoses, ii) production

of ethanol and octane, iii) production of same products of scenario i with cogeneration

system and iv) production of same products of scenario ii with cogeneration system. The

comparison of the evaluated scenarios was performed using modern process-engineering

tools. Each scenario was evaluated from a technical and economic point of view. The

chemical composition of CCS was determined experimentally. The chemical composition

of raw materials was also used as the starting point in the processes simulation.

6.2.3 Scenarios description

For the evaluation of the processes from CCS four scenarios were included. For all

scenarios, the amount feedstock was 5 tons/h (equivalent to 40,000 tons/year). This

feedstock value represents approximately 0.05 % of biomass in Colombia for 2014. The

raw material composition was shown in the chapter 3.

The scenarios are based on inclusion of cogeneration system in scenarios 1 and 2. In this

way, a description of processes from CCS included in this study is shown in Table 6-6. This

description indicates the distribution of materials across the processes and also

technologies for each product. The first and second scenario described the production of

ethanol and furfural, ethanol and octane respectively, without cogeneration system. In the

third and fourth scenario are obtained the same products corresponding to scenarios 1 and

2 respectively, but with system cogeneration. In these scenarios, the cogeneration

generated low pressure steam that was able to supply the heat requirements in processes.

The aim of the evaluation of the four scenarios is basically done in order to compare each

other in terms of performance from the techno-economic point of view. This comparison is

the basis to decide which could be the best alternative of process. Figure 6-6 shows two

technological schemes corresponding to the scenarios 1 and 2 and formation of the

respective products.

Chapter 6 112

Table 6-5 Scenarios description for process schemes from CCS.

Scenario Products


Sc. 1

Sc. 3

Furfural

Ethanol

Electricity

(Sc. 3)

Hemicellulose hydrolysis

Sulfuric acid 2% v/v.

Cellulose hydrolysis

Enzymatic hydrolysis.

Ethanol production

Continuous Bioreactor.


Furfural production Xylose

dehydration. Liquid-liquid

extraction with toluene and

distillation.

Cogeneration (Sc. 3)

Combined cycle

Ethanol production

Glucose from cellulose.

Furfural production

Xylose from hemicellulose.

Cogeneration

Residual lignocellulosic

biomass from hydrolysis

Sc. 2

Sc. 4

Ethanol

Octane

Furfural

Electricity

(Sc. 4)





Ethanol production


Saccharomyces Cerevisiae

Furfural production

Xylose dehydration.

Octane production

Aldolcondensation with

acetone. Hydrogenation.


Cogeneration (Sc. 4)

Combined cycle

Ethanol production

Glucose from cellulose.

Furfural production

Xylose from hemicellulose.

Octane production

Furfural from xylose.

Cogeneration

Residual lignocellulosic

biomass from hydrolysis


Figure 6-6 Process schemes to scenarios 1 and 2 from CCS.

6.2.4 Process description

The description of production processes to obtain sugars, ethanol, furfural and octane are

shown above in the section 2.8.1.

Cogeneration system

For this section the technology used for cogeneration is the biomass integrated gasification

combined cycle (BIGCC) as described Rincon et al. (2013) & Balat et al. (2009), [132],

[133]. Basic elements of BIGCC system include biomass dryer, gasification chamber, gas

Chapter 6 114

turbine and heat steam recovery generator (HRSG). Gasification is a thermo-chemical

conversion technology of carbonaceous materials (coal, petroleum coke and biomass), to

produce a mixture of gaseous products (CO, CO2, H2O, H2, CH4) known as syngas added

to small amounts of char and ash. Gasification temperatures range between 875-1275 K

[59]. The gas properties and composition of syngas changes according to the gasifying

agent used (air, steam, steam-oxygen, oxygen-enriched air), gasification process and

biomass properties [59]. Syngas is useful for a broader range of applications, including

direct burning to produce heat and power or high quality fuels production or chemical

products such as methanol [134], [135]. A gas turbine is a rotator engine that extracts

energy from a flow combustion gas. It is able to produce power with an acceptable electrical

efficiency, low emission and high reliability. The gas turbine is composed by three main

sections: compression (air pressure is increased, aimed to improve combustion efficiency),

combustion (adiabatic reaction of air and fuel to convert chemical energy to heat) and

expansion (obtained pressurized hot gas at high speed passing through a turbine

generating mechanical work) [136]. The HRSG is a high efficiency steam boiler that uses

hot gases from a gas turbine o reciprocating engine to generate steam, in a thermodynamic

Rankine Cycle. This system is able to generate steam at different pressure levels.

According to process requirements a HSRG system can use single, double or even triple

pressure levels. Figure 6-7 shows the processing steps for the BIGCC technology. This

process scheme was added to the scenarios 3 and 4. The price of low pressure steam used

in this study was 1.57 USD per tonne.

Figure 6-7 Biomass integrated gasification combined cycle system. 1. Heat exchanger, 2. Splitter,

3. Compressor, 4. Gas turbine, 5. Dryer, 6. Gasification and combustion chamber, 7. Cyclone, 8. LP

pump, 9. Economizer, 10. LP drum, 11. Evaporator, 12. Super-heater.



In the present study were analyzed process schemes from CCS to obtain ethanol, furfural,

octane and energy. Particularly, for setting up the four different scenarios with their

respective technical-economic calculations. CCS is considered a second generation

feedstock to obtain biofuel (ethanol), bioproducts (furfural and octane) and bioenergy

(referred as co-generation).

Simulation results for ethanol, furfural and octane production from CCS are shown in Table

6-6. The mass flow of ethanol is the same in all scenarios since is used the same amount

of hydrolyzed cellulose. Furfural flow is different due to obtaining conditions. The scenarios

1 and 3 include separation system to obtain furfural at 95% as final product. On the contrary,

the scenarios 2 and 4 do not take into account this stage since the furfural is a platform

product to obtain octane as final product. The inclusion of octane as a final product is a

promising strategy due to a sustainable production and a high selling price of this alkane in

the market.

Table 6-6 Production capacities of top and secondary products per process scheme from CCS.

Scenario Ethanol (kg/h) Furfural (kg/h) Octane (kg/h) Electricity* (kWh)

Sc. 1

Sc. 3 665.15 739.31 ----- 73.49

Sc. 2

Sc. 4 665.15 984.98 931.023 30.24

* Electricity obtained corresponding to Sc. 3 and Sc. 4.

Economic Assessment

One of the best alternatives for reducing production costs is to decrease the energy

consumption during the production process by implementing more energy-efficient and

better-performing technologies. The energy consumption resulted from the simulations was

used to assess the implication of the process distribution choices and technologies

according to energy consumption and the effect of energy savings on production cost.

The economic analysis of the process schemes based on CCS was focused on the

influence of cogeneration system. In this way, one of the main priorities in the economic

evaluation was the determination of the energy requirements according to the description

of the different proposed scenarios. For all scenarios, the process that represents the larger

Chapter 6 116

energy consumption is the pretreatment stage (sugars production). This could be explained

because this is one of the stages which has more processing units and materials

conditioning operations.

Figure 6-8 shows the total costs for both the heat and power requirements per tonne of

biomass for the scenarios 1 and 2. The second scenario showed the higher energy

consumption in comparison with scenario 1 due to the addition of octane process.

Figure 6-8 Energy cost of stream requirement per tonne of CCS based on obtaining products.

The scenarios 3 and 4 corresponding to the addition of cogeneration system to scenarios

1 and 2 respectively. Power requirements of simple process schemes are satisfied by

cogeneration system. Remaining power flows are shown in the table 6-6 and are taken as

secondary product that generated economic gains to process schemes. Additionally, the

low pressure steam produced by cogeneration system meets the demand of scenarios 1

and 2 in a 96.78% and 46.92% respectively. These positive results represent an economic

advantage reflected in the reduction of production cost and demonstrates that scenarios 3

and 4 proposed are feasible.

The total cost distributions of the process schemes based on CCS are shown in Figure 6-

9. The highest cost corresponds to feedstock with 60-70% of the total cost followed by the

total utility costs and the capital depreciation with 15% and 26%, respectively. The addition

of the cogeneration system slightly increases the distribution to raw material costs (water

used in steam generation) and capital depreciation (number of equipments) but decreases

considerably the percentage of utilities.

0

10

20

30

40

50

60

70

80

Sc.1 Sc. 2

US

D p

er

ton

ne (

heat

an

d

ele

ctr

icit

y r

eq

uir

em

en

ts)

Low P. Steam (USD/ton) Electricity (USD/ton)


Figure 6-9 Distribution of total costs of process schemes based on CCS.

The economic margins for all scenarios are shown in Figure 6-10. For all the studied

scenarios, the economic margin of all products was positive. This result could be explained

by the fact that the sale prices of these products are higher than their production costs.

Then, the economic margins for furfural in scenarios 1 and 3 are slightly positive but the

considerably high economic margins for ethanol can subsidize this product. Overall, by

including cogeneration system for scenarios 1 and 2, production costs and gains are

minimized and maximized, respectively.

Figure 6-10 Economic margin per scenario and obtained products for process schemes based on

CCS.

0% 10% 20% 30% 40% 50% 60% 70% 80%

Total Raw Material Cost

Operating Labor Cost

Maintenance Cost

Total Utilities Cost

Operating Charges

Plant Overhead

G & A Cost

Capital Depreciation

Sc. 1 Sc. 2 Sc. 3 Sc. 4

0

10

20

30

40

50

60

70

80

90

Ethanol Furfural Octane

Econom

ic m

arg

in (

%)

Sc 1 Sc 2 Sc 3 Sc 4

Chapter 6 118

6.2.6 Conclusions

According to results obtained, scenarios proposed for CCS for the production of ethanol,

furfural, and octane were feasible. However, given the analysis developed, the scenario

that considers cogeneration system was the most recommended from economic point of

view. Furfural as a chemical platform to obtain bioproducts and biofuels can contribute to

the development of new catalytic conversion processes of furfural and its derivatives, which

in the future can lower the cost of their production. This could increase the scale of

production, which will result in the launch on the production of alternative fuels, which will

replace for conventional fuel.


6.3 Techno-economic and environmental analysis of the processes to obtain blends as additive for jet biofuels

6.3.1 Overview

Sugarcane bagasse and rice husk are one of the main agroindustrial wastes in Colombia.

The content of lignocellulosic material makes them attractive and interesting materials to

transform them into biofuels. In this section, the possibility to obtain alcohol mixtures as

biofuel additive or biofuel from SCB and RH was evaluated. The production processes were

designed and analyzed from techno-economic and environmental point of view. Raw

materials were compared to produce ethanol-butanol, and ethanol-alcohol mixture.

According to the economical results, SCB is the best raw material to obtain alcohols with

global economic margins of 44.1 and 66.8% for scenario 1 and 2 respectively. The

processes that considered SCB as raw material are the most environmentally friendly with

a potential environmental impact per kg product of 1.97 and 2.1 for scenarios 1 and 2

respectively.

6.3.2 Blends of biofuels as additive for jet fuels

Currently, there are concerns to reduce the fossil fuel dependence and therefore new

energy sources are being proposed to supply the increasing energy demand. As a

consequence, biomass appears as a promising alternative to produce environmentally

friendly biofuels with competitive advantages over non-renewable fuels [137]. Nowadays,

the lignocellulosic biomass is the main source of biofuels because with its content of

cellulose, hemicellulose and lignin can be produced any amount of products including

electricity [92]. The raw materials to produce biofuels have been developed from first

generation feedstocks (agricultural farming), second generation (residuals) and third

generation (algae) [138].

Among potential biofuels, bioethanol has become one of the most important biofuels as

gasoline additive and widely used in countries such as USA, Brazil and Colombia.

Alternatively, biodiesel also has been a popular biofuel, which is essentially composed of

methyl or ethyl ester of fatty acids and has been used as an additive in diesel in the

Chapter 6 120

transportation sector [138]. Another important biofuel is biobutanol that has gained visibility

in recent years as a replacement for gasoline. Butanol has unique properties as a fuel. The

energy content of butanol (99,840 Btu per gallon) is 86% of the energy content of gasoline.

Other alternative of fuels, is use of mixed alcohol formulas that can be used as a fuel

additive in gasoline, diesel, jet fuel, aviation gasoline, heating oil and bunker oil. The

formulation of mixed alcohols can contain C1-C5 alcohols, or in the alternative, C1-C8

alcohols or higher C1-C10 alcohols in order to boost energy content. Alcohol fuel additives

have been found as oxygenate for internal combustion engines, reducers of emissions and

increasers combustion efficiencies [32], [33].

In this section, two lignocellulosic materials were considered in order to evaluate the viability

of the production of ethanol, butanol and mixture of alcohols. These consists in sugarcane

bagasse (SCB) and rice husk (RH). The following two scenarios were evaluated: i)

production of ethanol and butanol and ii) production of ethanol and mixture of alcohols

(butanol, octanol, hexanol, decanol, dodecanol, tetradecanol, hexadecanol, octadecanol

and eicosanol). Each scenario was evaluated from a techno-economic and environmental

point of view. The chemical composition of SCB and RH was determined experimentally.

The chemical composition of raw materials was also used as the starting point in the

processes simulation.

6.3.3 Process and scenarios description

SCB and RH are the feedstock to assess the production of ethanol-butanol and ethanol-

mixture of alcohols. Two scenarios were studied per each raw material. The feed for all

processes was 5 tons/h (equivalent to 40000 tons/year). The raw material compositions

were shown in the chapter 3. The description of scenarios and process schemes are

presented in the table 6-7 and figures 6-11 and 6-12 respectively. The description of

production processes to obtain ethanol, butanol and mixture of alcohols are shown above

in the section 2.8.1.


Table 6-7 Scenarios description from RH and SCB.

Scenario Products Technology Distribution

Sc. 1

Ethanol

Butanol





Ethanol production


Zymomonas mobilis.

Butanol production

ABE fermentation

Clostridium beijerinckii.

Ethanol production

100% of xylose and

20% of glucose.

Butanol production

80% of glucose from

cellulose.

Sc. 2

Ethanol

Mixture of

alcohols





Ethanol production


Zymomonas mobilis.

Alcohols production

Dehydration of ethanol to

ethylene.

Ziegler process to obtain alcohol

C2-C20.

Ethanol production

Glucose and xylose

Alcohols production

40% of ethanol.

Chapter 6 122

Figure 6-11 Process scheme to obtain ethanol and butanol.

Figure 6-12 Process scheme to obtain ethanol and mixture of alcohols.


Techno-economic assessment

SCB and RH are composed by 70% and 56% of holocellulosic material respectively,

distributed in 46% and 40% of glucose 15% and 23% of xylose for SCB and RH

respectively. Evidently, the high availability of glucose and xylose in SCB leads to higher


flow of products of interest. Ash content in RH exceeds the normal levels leading to a

displacement of the material to convert in sugars. For this reason the flows of products for

RH decrease substantially in comparison with SCB as shows the table 6-8. The yields

associated to processes developed in this section are 0.47 grams of ethanol per gram of

sugars, 0.22 grams of butanol per gram of glucose and 0.56 grams of mixture of alcohols

per gram of ethanol. The mixture of alcohols is composed by 0.02 of butanol, 0.13 of

octanol, 0.06 of hexanol, 0.19 of decanol, 0.21 of dodecanol, 0.18 of tetradecanol, 0.13 of

hexadecanol, 0.08 of octadecanol and 0.04 of eicosanol in mass fraction (C4 to C20).

Table 6-8 Production capacities of products per scenario.

Scenario Raw material Ethanol (kg/h) Butanol (kg/h) Mix alcohols (kg/h)

Sc. 1 SCB 531.67 309.26 -----

RH 329.89 249.22 -----

Sc. 2 SCB 575.80 ----- 258.94

RH 530.40 ----- 178.93

The production costs for SCB and RH to obtain ethanol, butanol and mixture of alcohols

are shown in the table 6-9. In economic terms, the behavior respect to the raw materials is

the same, that is to say, the production costs for SCB are lower due to high flows of products

compared with RH. In spite of greater production cost of products for RH, this material

continues to maintain a positive economic margin as show the figures 6-13 and 6.14.

Table 6-9 Production cost of products from SCB and RH.

Item Sc. 1 Sc. 2

Total production cost Ethanol (USD/kg)

SCB 0.54 0.78

RH 0.9 1.1

Total production cost Butanol (USD/kg)

SCB 1.12 -----

RH 1.74 -----

Total production cost Mix alcohols (USD/kg)

SCB ----- 0.42

RH ----- 0.47

Chapter 6 124

Individual economic margins for ethanol are 49.5 and 27.1% for SCB and RH respectively.

For butanol are 41.1 and 8.4% for SCB and RH respectively. Global economic margins are

indicated in figure 6-13, the gains for RH are affected mainly by availability of holocellulosic

material to transform and the limitations in the process to obtain butanol, related with yield

of ABE fermentation and purification of final product.

Figure 6-13 Global economic margins to obtain ethanol and butanol (Sc. 1) from SCB and RH.

Figure 6-14 shows the global economic margins of 66.8 and 60.3% to produce ethanol and

mixture of alcohols from SCB and RH respectively. As can be seen, there is a brief

difference respect to raw materials due to individual economic margins for ethanol that are

15.9 and -3.74% for SCB and RH respectively. These results, are directly affected by the

content of holocellulose. In the case of rice husk this content is minor since ash content

exceeds normal values of any lignocellulosic biomass. Ash content of RH can be source of

silica-based products but in this work are not considered.

0.0

10.0

20.0

30.0

40.0

50.0

Eco

no

mic

marg

in (

%)

SCB RH


Figure 6-14 Global economic margins to obtain ethanol and mixture of alcohols (Sc. 2) from SCB

and RH.

Environmental assessment

The results of the potential environmental impact per kilogram of products are presented in

Figure 6-15 and 6-16 for scenarios 1 and 2. The results show that the process that

considered as SCB as raw material are the most environmentally friendly due to the fact

that this biomass contains less lignin and therefore has low deposition of solid waste to the

outside. For all the evaluated scenarios, the impacts that contribute the most to the PEI

were the photochemical oxidation potential (due to the gases emissions in fermentation

process) and the terrestrial toxicity potential (due to the emissions of solid material). The

PCOP for scenario 1 is higher than for 2 due to scenario 1 account with two fermentation

processes.

Figure 6-15 PEI per kg of product (ethanol and butanol).

0.00

10.00

20.00

30.00

40.00

50.00

60.00

70.00E

co

no

mic

marg

in (

%)

SCB RH

0.00E+00

5.00E-01

1.00E+00

1.50E+00

2.00E+00

2.50E+00

3.00E+00

HTPI HTPE TTP ATP GWP ODP PCOP AP Total

PE

I/k

g o

f p

rod

uc

t

SCB RH

Chapter 6 126

Figure 6-16 PEI per kg of product (ethanol and mixture of alcohols).

6.3.5 Conclusions

This work brings on to the table an interesting discussion about the design and analysis of

potential technological schemes to produce promising jet biofuel blends. Special attention

is paid to the use of second generation feedstocks in countries from tropical regions. The

economic evaluation indicates that the production cost of the two blends studied, although

are economically viable, when SCB is used as raw material there is a high economic

margin, product of a higher holocellulosic fiber content convertible to reducing sugars.

0.00E+00

5.00E-01

1.00E+00

1.50E+00

2.00E+00

2.50E+00

3.00E+00

HTPI HTPE TTP ATP GWP ODP PCOP AP Total

PE

I/k

g o

f p

rod

uc

t

SCB RH


6.4 Lignocellulosic biomass to obtain sugars, ethanol, PHB and energy: Design and analysis of processes

6.4.1 Overview

This section presents a techno-economic assessment for obtain sugars, fuel, biopolymer

and energy from fique bagasse and rice husk through four scenarios per each raw material.

The two lignocellulosic raw materials are compared to obtain glucose, xylose, ethanol, PHB,

octane and nonane according cellulose and hemicellulose content transformable. Designed

processes were analyzed to produce an only product and determine its economic viability.

The results showed an average economic margin for glucose, xylose, ethanol, PHB, octane

and nonane of 50.3, 15.8, 25.7, 63.1, 53.6 and 82.3% respectively.

6.4.2 Second generation biomass to obtain interesting products

Currently, there are concerns to reduce the oil dependence, and therefore new feedstock

sources are being proposed to supply the increasing products demand. Then, biomass

appears as a promising alternative to produce bioproducts and environmentally friendly

biofuels with competitive advantages over non-renewable fuels. Countries such as

Colombia, located in tropical regions have an important production of raw materials and

specifically a large amount of biomass. Some of them are of first and second generation:

First generation raw materials are designed to obtain multiple products of added value,

while second generation feedstocks are generally residues obtained from the processing

of first generation feedstocks. Both raw materials are excellent platforms for obtaining

biofuels, biochemicals and biopolymers and energy.

Sugars as glucose and xylose are the initials products that can be obtain from

lignocellulosic biomass. These products are considered a platform to generate alcohols,

organic acids, among others biochemicals. Biofuels as ethanol, this alcohol has become

one of the most important biofuels as gasoline additive and widely used in countries such

as USA, Brazil and Colombia. Biopolymers as PHB, the use of PHB as biodegradable

plastic is desirable since the non-biodegradable plastics disposal, after they are used,

causes significant ecological problems. PHB has many potential applications in medicine,

Chapter 6 128

veterinary practice and agriculture due to its biodegradability. Bioenergy as alkanes

components of biofuels (octane and nonane) and jet fuels.

In this section, two lignocellulosic materials were considered in order to evaluate the viability

of the production of sugars, alcohol, polymer and energy. These consists in fique bagasse

(FB) and rice husk (RH). The following two scenarios were evaluated: i) production of

glucose and xylose ii) production of ethanol, iii) production of PHB and iv) production of

octane and nonane. Each scenario was evaluated from a techno-economic point of view.

The chemical composition of FB and RH was determined experimentally. The chemical

composition of raw materials was also used as the starting point in the processes

simulation.

6.4.3 Scenarios and process description

For the evaluation of the proposed processes from FB and RH four scenarios were included

per each raw material. The scenarios consider the production of sugars (glucose and

xylose), fuel (ethanol), biopolymer (PHB) and energy (octane and nonane). For all

scenarios, the feedstock was 20 tons h-1 (equivalent to 160,000 tons per year). The raw

material compositions were shown in the chapter 3.

The scenarios are based on design and analysis to obtain interesting products for the same

amount of FB and RH as feedstocks. In this way, a description of processes from FB and

RH included in this study is shown in Table 6-10. This description indicates the distribution

of materials across the processes and also technologies for each product. The aim of the

evaluation is analysis of four scenarios from two raw materials that is basically done in order

to compare each other in terms of performance from the techno-economic point of view.

This comparison is the basis to decide which could be the best alternative of process

according to raw material. Figures 6-17, 6-18, 6-19 and 6-20 show the four processes from

lignocellulosic biomass designed, analyzed and evaluated to obtain sugars, fuel,

biopolymer and energy respectively. The description of production processes are shown

above in the section 2.8.1.


Table 6-10 Scenarios description to produce sugars, fuel, biopolymer and energy.

Scenario Products Technology Distribution

Sc. 1 Glucose

Xylose





Glucose production

100% of cellulose

Xylose production

100% of hemicellulose

Sc. 2 Ethanol





Ethanol production


Z. mobilis.

Ethanol production

100% glucose and xylose

Sc. 3 PHB





PHB production


Ralstonia eutropha

PHB production

100% glucose and xylose

Sc. 4 Octane

Nonane





Furfural production

Xylose dehydration.

Octane production


Hydrogenation.


HMF production

Glucose dehydration.

Nonane production


Hydrogenation.

Dehydrogenation/hydrogenation.

Furfural production

100% of xylose from

hemicellulose.

HMF production

100% of glucose from

cellulose.

Octane production


Nonane production


Chapter 6 130

Figure 6-17 Process scheme to obtain glucose and xylose.

Figure 6-18 Process scheme to obtain ethanol.

Figure 6-19 Process scheme to obtain PHB.


Figure 6-20 Process scheme to obtain octane and nonane.


Simulations of both feedstock were used to generate their respective mass and energy

balances, which are the basic input for the technical and economic analysis. Table 6-11

shows the production of each product per 20 tons of raw material fed (FB and RH). As can

see FB has a slight advantage over RH for the cellulose content, but RH has a greater

content of hemicellulose. These raw materials have a composition very similar of

holocellulosic fibers. Their difference is that FB exhibits high amount of extractives

associated with high chlorophyll content. On the contrary, RH is characterized for their

considerable content of ashes referred to the silica content.

The yields do not change between the different processes to each raw material. The overall

yields according to kinetics studied for conversion of lignocellulosic material to sugars were

0.71 grams of xylose per grams of hemicellulose and 0.64 grams of glucose per grams of

cellulose. In the case of ethanol production, the yield obtained was 0.47 grams per gram of

glucose and xylose. For PHB, the yield obtained was 0.12 grams per gram of glucose.

Finally, for octane and nonane were obtained an average yields of 0.08 and 0.13 grams

per gram of fresh raw material respectively.

Chapter 6 132

Table 6-11 Production capacities per scenario from FB and RH.

Scenario 1

Raw material Glucose (kg/h) Xylose (kg/h)

FB 5664.65 2060.61

RH 5259.35 2253.59

Scenario 2

Raw material Ethanol (kg/h)

FB 3686.14

RH 3371.54

Scenario 3

Raw material PHB (kg/h)

FB 811.1

RH 649.8

Scenario 4

Raw material Octane (kg/h) Nonane (kg/h)

FB 1566.48 2902.03

RH 1698.11 2327.45

A goal of the economic assessment is to evaluate the total production cost and the income

by product sales. In this way, the total production cost of sugars, fuel, biopolymer and

energy were calculated for the all schemes. Hence, Table 6-12 to Table 6-15 shows the

production cost of the product considered in this work. The main factor that affect the

production costs is the availability of cellulose and hemicellulose content in the feedstock.

When the base of the products is the glucose, the FB is the ideal material due to lower

production costs but if the base of the products is the xylose, RH is the best raw material.

In all scenarios, the items that contribute in high proportion to production cost are: raw

material costs, utility costs and depreciation. Raw material costs are related with the costs

of enzymes, reagents and solvents. Utility costs involve cooling and heating fluids and

electricity. Finally, depreciation implies the periodic decrease in the value of the equipment.


Table 6-12 Total production cost of glucose and xylose from FB and RH.

Item Cost and

Share (%)

Glucose (USD/kg) Xylose (USD/kg)

FB RH FB RH

Raw materials Cost

Share

0.074

0.203

0.072

0.166

0.929

0.728

0.875

0.685

Operating Labor cost Cost

Share

0.005

0.013

0.006

0.014

0.016

0.012

0.014

0.011

Maintenance cost Cost

Share

0.002

0.006

0.003

0.007

0.007

0.006

0.007

0.006

Utilities cost Cost

Share

0.218

0.597

0.272

0.629

0.194

0.152

0.243

0.195

Operating charges Cost

Share

0.001

0.003

0.002

0.004

0.004

0.003

0.004

0.003

Plant overhead Cost

Share

0.004

0.010

0.011

0.005

0.011

0.009

0.011

0.009

General &

Administration cost

Cost

Share

0.027

0.073

0.078

0.034

0.085

0.067

0.079

0.063

Depreciation Cost

Share

0.034

0.094

0.093

0.040

0.030

0.024

0.036

0.029

Total Cost 0.37 0.43 1.28 1.25

Share 100.0 100.0 100.0 100.0

Chapter 6 134

Table 6-13 Total production cost of ethanol from FB and RH.

Item Cost and Share

(%)

Ethanol (USD/kg)

FB RH

Raw materials Cost

Share

0.176

0.233

0.186

0.221


Share

0.005

0.006

0.005

0.006


Share

0.005

0.006

0.006

0.007

Utilities cost Cost

Share

0.471

0.624

0.534

0.634


Share

0.001

0.002

0.001

0.002

Plant overhead Cost

Share

0.005

0.006

0.005

0.006

General & Administration

cost

Cost

Share

0.053

0.070

0.059

0.070

Depreciation Cost

Share

0.040

0.053

0.045

0.053

Total Cost 0.75 0.84

Share 100.0 100.0


Table 6-14 Total production cost of PHB from FB and RH.

Item Cost and Share

(%)

PHB (USD/kg)

FB RH

Raw materials Cost

Share

0.296

0.291

0.476

0.298


Share

0.032

0.031

0.059

0.037


Share

0.071

0.070

0.110

0.069

Utilities cost Cost

Share

0.079

0.077

0.131

0.082


Share

0.008

0.008

0.015

0.009

Plant overhead Cost

Share

0.051

0.050

0.084

0.053

General & Administration

cost

Cost

Share

0.086

0.084

0.070

0.044

Depreciation Cost

Share

0.396

0.389

0.654

0.409

Total Cost 1.02 1.56

Share 100.0 100.0

Chapter 6 136

Table 6-15 Total production cost of Octane and Nonane from FB and RH.

Item Cost and

Share (%)

Octane (USD/kg) Nonane (USD/kg)

FB RH FB RH

Raw materials Cost

Share

2.157

0.670

2.108

0.645

2.201

0.842

2.736

0.844


Share

0.008

0.003

0.008

0.003

0.004

0.002

0.006

0.002


Share

0.015

0.005

0.014

0.004

0.008

0.003

0.010

0.003

Utilities cost Cost

Share

0.629

0.195

0.744

0.228

0.186

0.071

0.217

0.067


Share

0.002

0.001

0.002

0.001

0.001

0.000

0.002

0.000

Plant overhead Cost

Share

0.012

0.004

0.011

0.003

0.006

0.002

0.008

0.003

General &

Administration cost

Cost

Share

0.291

0.090

0.279

0.085

0.157

0.060

0.203

0.063

Depreciation Cost

Share

0.105

0.033

0.102

0.031

0.050

0.019

0.060

0.019

Total Cost 3.22 3.27 2.61 3.24

Share 100.0 100.0 100.0 100.0

A criteria to calculate the feasibility of a process, is the combination of the total production

cost of products directly related with the sales of them. Thus a profit margin can be included

as the relation of sales and total production cost. In this way, Figure 6-21 shows the profit

margin for all products for each raw material. As can be seen the processes that considered

the glucose as basis for their obtaining have higher rates of viability. The high content of

cellulose in FB makes stand out against RH. On the contrary, both materials have a similar

hemicellulose content that does not do very different the economic margins for the products

obtained from xylose.


Figure 6-21 Economic margin per raw material of products obtained.

6.4.5 Conclusions

The versatility of lignocellulosic biomass to obtain a great amount of products is remarkable.

However, in some case the process technologies are not sufficiently adequate to allow that

the biological processes are as competitive as conventional. Given the above, can be

proposed an optimization work to improve processes related to operating conditions,

genetic modification of microorganisms and separation and purification technologies.

0

10

20

30

40

50

60

70

80

90

Glucose Xylose Ethanol PHB Octane Nonane

Eco

no

mic

marg

in (

%)

FB RH

7. Conclusions

In the last years it has been suggested that lignocellulosic biomass could be used as an

ideal source of biofuels and biochemicals. It was briefly showed the potentiality of Colombia

to produce these products due to its location in tropical region and its diversity. In this work

is indicated the great opportunity of obtain jet fuel range alkanes through the catalytic

transformation of lignocellulosic biomass. The results given an encouraging response and

open an additional possibility to the use of agroindustrial wastes to produce jet biofuels and

subsidize the dependency of oil sources. Also, according to the study developed is possible

suggest additives, compounds by conventional biofuels for the use in aircraft industry that

in general comply with the requirements of international standards in physicochemical

properties.

The success in the obtaining of interesting products in this work is based in the initial yields

of sugars which in turn depends of efficiency and the operation conditions in the extraction

process in pretreatment step. Moreover, it was shown that most of the biomass has a high

potential towards conversion to bioproducts in spite of their limitations relating the content

of holocellulosic fiber, collecting, storage and initial conditioning. This work contributes to

implementation of simultaneous processes from agroindustrial wastes for obtaining

ethanol, furan-based compounds and alkane precursor to obtain jet biofuel, focusing on the

comprehensive utilization of raw materials and achieving considerable yields. Also, this

work promotes the combination and feedback between chemical and biological processes

due to use of mixed metal oxides and microorganisms as catalysts for conversion of the

same raw material.

Chapter 7 140

Colombia as a tropical country has the potential to produce multiple crops that are source

of great amount of residues. This wastes can be used as feedstock to produce fuels,

fertilizers, chemicals. However, the catalytic conversion of agroindustrial wastes to produce

biochemicals in this country has a substantial deficiency. In this thesis, four residues were

selected according to national production and availability to assess the possibility of obtain

sugars, alcohol, furan-based compounds and alkane precursor. According with the results,

the raw materials used are defined as promising feedstock for the strengthening of this

industry. The integral use of biomass allows creating high profitability processes focused

on the growing biorefinery concept where individual processes are supported, provided with

feedstock and also economically subsidized. This increase on economic sustainability has

an effect on the competitiveness of industries based on these kinds feedstock.

A. Annex: Kinetic parameters for simulation procedures

Table A-1 Kinetic models used in simulation procedures.

Acid hydrolysis

Kinetic model Parameters Conditions Ref

𝐻𝑒𝑚𝑖𝑐𝑒𝑙𝑙𝑢𝑙𝑜𝑠𝑒 𝑡𝑜 𝑥𝑦𝑙𝑜𝑠𝑒

𝑘1𝑟 = 𝐴1 ∗ 𝐶𝐴𝑛1 ∗ 𝑒𝑥𝑝 (

−𝐸𝑎1

𝑅𝑇)

𝑋𝑦𝑙𝑜𝑠𝑒 𝑡𝑜 𝑓𝑢𝑟𝑓𝑢𝑟𝑎𝑙

𝑘2𝑟 = 𝐴2 ∗ 𝐶𝐴𝑛2 ∗ 𝑒𝑥𝑝 (

−𝐸𝑎2

𝑅𝑇)

𝐶𝐴 = 𝑎𝑐𝑖𝑑 𝑐𝑜𝑛𝑐𝑒𝑛𝑡𝑟𝑎𝑡𝑖𝑜𝑛 (%𝑤𝑡)

𝐵𝑎𝑙𝑎𝑛𝑐𝑒 𝑒𝑞𝑢𝑎𝑡𝑖𝑜𝑛𝑠

𝛾ℎ𝑒𝑚 = −𝑘1𝑟 ∗ 𝐶ℎ𝑒𝑚

𝛾𝑥𝑦𝑙 = (𝑘1𝑟 ∗ 𝐶ℎ𝑒𝑚) − (𝑘2𝑟 ∗ 𝐶𝑥𝑦𝑙)

𝛾𝑓𝑢𝑟 = 𝑘2𝑟 ∗ 𝐶𝑥𝑦𝑙

𝑡 =1

𝜏 𝑡𝑖𝑚𝑒

𝑑ℎ𝑒𝑚 = 𝑡 ∗ (𝐶ℎ𝑒𝑚𝑓 − 𝐶ℎ𝑒𝑚𝑖) + 𝛾ℎ𝑒𝑚

𝑑𝑥𝑦𝑙 = 𝑡 ∗ (𝐶𝑥𝑦𝑙𝑓 − 𝐶𝑥𝑦𝑙𝑖) + 𝛾𝑥𝑦𝑙

𝑑𝑓𝑢𝑟 = 𝑡 ∗ (𝐶𝑓𝑢𝑟𝑓 − 𝐶𝑓𝑢𝑟𝑖) + 𝛾𝑓𝑢𝑟

𝑅 = 8.314 𝐽 𝑚𝑜𝑙−1𝐾−1

𝐴1 = 1.4𝑒14 𝑚𝑖𝑛−1

𝐴2 = 3.3𝑒10 𝑚𝑖𝑛−1

𝐸𝐴1 = 111600 𝐽 𝑚𝑜𝑙−1

𝐸𝐴2 = 95700 𝐽𝑚𝑜𝑙−1

𝑛1 = 0.68

𝑛2 = 0.4

𝜏 = 20ℎ

𝑅𝑒𝑎𝑐𝑡𝑜𝑟 𝑡𝑦𝑝𝑒:

𝐶𝑆𝑇𝑅

𝑇𝑒𝑚𝑝𝑒𝑟𝑎𝑡𝑢𝑟𝑒:

373.15𝐾

𝐴𝑐𝑖𝑑 𝑐𝑜𝑛𝑐𝑒𝑛𝑡𝑟𝑎𝑡𝑖𝑜𝑛:

2% 𝑤𝑡/𝑤𝑡

[70]



𝐶𝑒𝑙𝑙𝑢𝑙𝑜𝑠𝑒 𝑡𝑜 𝑐𝑒𝑙𝑙𝑢𝑏𝑖𝑜𝑠𝑒

𝛾1 =𝑘1𝑟𝐶𝑒1𝑏𝑅𝑆𝐶𝑆

1 +𝐶𝑔2

𝑘1𝑖𝑔2+

𝐶𝑔

𝑘1𝑖𝑔+

𝐶𝑥𝑦

𝑘1𝑖𝑥𝑦

𝐶𝑒𝑙𝑙𝑢𝑙𝑜𝑠𝑒 𝑡𝑜 𝑔𝑙𝑢𝑐𝑜𝑠𝑒

142 Jet fuel production from agroindustrial wastes through of furfural platform

𝛾2 =𝑘2𝑟(𝐶𝑒1𝑏 + 𝐶𝑒2𝑏)𝑅𝑆𝐶𝑆

1 +𝐶𝑔2

𝑘2𝑖𝑔2+

𝐶𝑔

𝑘1𝑖𝑔+

𝐶𝑥𝑦

𝑘2𝑖𝑥𝑦

𝐶𝑒𝑙𝑙𝑢𝑏𝑖𝑜𝑠𝑒 𝑡𝑜 𝑔𝑙𝑢𝑐𝑜𝑠𝑒

𝛾3 =𝑘3𝑟𝐶𝑒2𝑓𝐶𝑔2

𝑘3𝑀 (1 +𝐶𝐺

𝑘3𝑖𝑔+

𝐶𝑥𝑦

𝑘3𝑖𝑥𝑦) + 𝐶𝑔2

𝐸𝑛𝑧𝑦𝑚𝑒 𝑎𝑑𝑠𝑜𝑟𝑝𝑡𝑖𝑜𝑛

𝐶𝑒𝑖𝑏 =𝐸𝑖𝑚𝑎𝑥𝑘𝑖𝑎𝑑𝐶𝑒𝑖𝑓𝐶𝑆

1 + 𝑘𝑖𝑎𝑑𝐶𝑒𝑖𝑓

𝐸𝑛𝑧𝑦𝑚𝑒

𝐶𝑒𝑖𝑡 = 𝐶𝑒𝑖𝑓 + 𝐶𝑒𝑖𝑏

𝑆𝑢𝑏𝑠𝑡𝑟𝑎𝑡𝑒

𝑅𝑆 =𝐶𝑆

𝑆0

𝑇𝑒𝑚𝑝𝑒𝑟𝑎𝑡𝑢𝑟𝑒 𝑑𝑒𝑝𝑒𝑛𝑑𝑒𝑛𝑐𝑒

𝑘𝑖𝑟 = 𝑘𝑖 ∗ 𝑒𝑥𝑝 (−𝐸𝑎

𝑅(

1

𝑇1

−1

𝑇2

))

𝐶𝑜𝑚𝑝𝑜𝑛𝑒𝑛𝑡𝑠 𝑘𝑖𝑛𝑒𝑡𝑖𝑐

𝑑𝐶𝑆 = −𝛾1 − 𝛾2 𝑐𝑒𝑙𝑙𝑢𝑙𝑜𝑠𝑒

𝑑𝐶𝑔2 = 1.05𝛾1 − 𝛾3 𝑐𝑒𝑙𝑙𝑢𝑏𝑖𝑜𝑠𝑒

𝑑𝐶𝑔 = 1.111𝛾2 + 1.053𝛾3 𝑔𝑙𝑢𝑐𝑜𝑠𝑒

𝑅 = 8.314 𝐽 𝑚𝑜𝑙−1𝐾−1

𝑘1 = 22.3 𝑔 𝑚𝑔−1ℎ−1

𝑘2 = 7.18 𝑔 𝑚𝑔−1ℎ−1

𝑘3 = 285.5 𝑔 𝑚𝑔−1ℎ−1

𝐸𝑎 = −23190 𝐽𝑚𝑜𝑙−1

𝑘1𝑖𝑔2 = 0.015 𝑔𝐿−1

𝑘1𝑖𝑔 = 0.1 𝑔𝐿−1

𝑘1𝑖𝑥𝑦 = 0.1 𝑔𝐿−1

𝑘2𝑖𝑔2 = 132 𝑔𝐿−1

𝑘2𝑖𝑔 = 0.04 𝑔𝐿−1

𝑘2𝑖𝑥𝑦 = 0.2 𝑔𝐿−1

𝑘3𝑖𝑔 = 3.9 𝑔𝐿−1

𝑘3𝑖𝑥𝑦 = 201 𝑔𝐿−1

𝑘3𝑀 = 24.3 𝑔𝐿−1

𝐸1𝑚𝑎𝑥 = 0.06 𝑔𝑔−1

𝐸2𝑚𝑎𝑥 = 0.01 𝑔𝑔−1

𝑘1𝑎𝑑 = 0.4 𝑔𝑔−1

𝑘2𝑎𝑑 = 0.1 𝑔𝑔−1


𝐶𝑆𝑇𝑅


308.15𝐾

[86]

Fermentation to ethanol from glucose

Kinetic model Parameters Ref

𝐵𝑖𝑜𝑚𝑎𝑠𝑠

𝛾𝑥 =𝜇𝑚𝑎𝑥𝑆

𝐾𝑆 + 𝑆exp (−𝐾𝑖𝑆) (1 −

𝑋

𝑋𝑚𝑎𝑥 +)

𝑚

(1 −𝑃

𝑃𝑚𝑎𝑥

)𝑛

𝑋

𝐸𝑡ℎ𝑎𝑛𝑜𝑙

𝛾𝑝 = 𝑌𝑝𝑥𝛾𝑥 + 𝑚𝑝𝑋

𝐺𝑙𝑢𝑐𝑜𝑠𝑒

𝛾𝑠 =𝛾𝑥

𝑌𝑥

+ 𝑚𝑥𝑋


𝑑𝑋 = 𝑡(𝑋𝑓 − 𝑋𝑖) + 𝛾𝑥 𝑏𝑖𝑜𝑚𝑎𝑠𝑠

𝑑𝑆 = 𝑡 ∗ (𝑆𝑓 − 𝑆𝑖) − 𝛾𝑆 𝑔𝑙𝑢𝑐𝑜𝑠𝑒

𝑑𝑃 = 𝑡 ∗ (𝑃𝑓 − 𝑃𝑖) + 𝛾𝑝 𝑒𝑡ℎ𝑎𝑛𝑜𝑙

𝜇𝑚𝑎𝑥 = 0.426ℎ−1

𝐾𝑖 = 0.002

𝑃𝑚𝑎𝑥 = 86.072

𝑋𝑚𝑎𝑥 = 54.474

𝑌𝑝𝑥 = 0.03831

𝐾𝑠 = 4.1

𝑚𝑝 = 0.1

𝑚𝑥 = 0.2

𝑚 = 1

𝑛 = 1.5


𝐶𝑆𝑇𝑅

[87]

Annex A. Kinetic parameters for simulation procedures 143

𝑡 =1

𝜏 𝑡𝑖𝑚𝑒

𝑇𝑒𝑚𝑝𝑒𝑟𝑎𝑡𝑢𝑟𝑒: 310𝐾

𝑀𝑖𝑐𝑟𝑜𝑜𝑟𝑔𝑎𝑛𝑖𝑠𝑚:

𝑆𝑎𝑐𝑐ℎ𝑎𝑟𝑜𝑚𝑦𝑐𝑒𝑠 𝑐𝑒𝑟𝑒𝑣𝑖𝑠𝑖𝑎𝑒

𝜏 = 40ℎ

Fermentation to ethanol from glucose and xylose

Kinetic model Conditions Ref

𝑀𝑖𝑐𝑟𝑜𝑏𝑖𝑎𝑙 𝑔𝑟𝑜𝑤𝑡ℎ 𝑓𝑜𝑟 𝑔𝑙𝑢𝑐𝑜𝑠𝑒

𝛾𝑥1 = 𝜇𝑚𝑎𝑥1 (𝑠1

𝐾𝑠𝑥1 + 𝑠1

) (1 −𝑝 − 𝑃𝑖𝑥1

𝑃𝑚𝑥1 − 𝑃𝑖𝑥1

) (𝐾𝑖𝑥1

𝐾𝑖𝑥1 + 𝑠1

)

𝑀𝑖𝑐𝑟𝑜𝑏𝑖𝑎𝑙 𝑔𝑟𝑜𝑤𝑡ℎ 𝑓𝑜𝑟 𝑥𝑦𝑙𝑜𝑠𝑒

𝛾𝑥2 = 𝜇𝑚𝑎𝑥2 (𝑠2

𝐾𝑠𝑥2 + 𝑠2

) (1 −𝑝 − 𝑃𝑖𝑥2

𝑃𝑚𝑥2 − 𝑃𝑖𝑥2

) (𝐾𝑖𝑥2

𝐾𝑖𝑥2 + 𝑠2

)

𝐶𝑜𝑛𝑠𝑢𝑚𝑝𝑡𝑖𝑜𝑛 𝑜𝑓 𝑔𝑙𝑢𝑐𝑜𝑠𝑒

𝛾𝑠1 = 𝑞𝑠𝑚𝑎𝑥1 (𝑠1

𝐾𝑠𝑠1 + 𝑠1

) (1 −𝑝 − 𝑃𝑖𝑠1

𝑃𝑚𝑠1 − 𝑃𝑖𝑠1

) (𝐾𝑖𝑠1

𝐾𝑖𝑠1 + 𝑠1

) 𝑥

𝐶𝑜𝑛𝑠𝑢𝑚𝑝𝑡𝑖𝑜𝑛 𝑜𝑓 𝑥𝑦𝑙𝑜𝑠𝑒

𝛾𝑠2 = 𝑞𝑠𝑚𝑎𝑥2 (𝑠2

𝐾𝑠𝑠2 + 𝑠2

) (1 −𝑝 − 𝑃𝑖𝑠2

𝑃𝑚𝑠2 − 𝑃𝑖𝑠2

) (𝐾𝑖𝑠2

𝐾𝑖𝑠2 + 𝑠2

) 𝑥

𝐸𝑡ℎ𝑎𝑛𝑜𝑙 𝑝𝑟𝑜𝑑𝑢𝑐𝑡𝑖𝑜𝑛 𝑓𝑜𝑟 𝑔𝑙𝑢𝑐𝑜𝑠𝑒

𝛾𝑝1 = 𝑞𝑝𝑚𝑎𝑥1 (𝑠1

𝐾𝑠𝑝1 + 𝑠1

) (1 −𝑝 − 𝑃𝑖𝑝1

𝑃𝑚𝑝1 − 𝑃𝑖𝑝1

) (𝐾𝑖𝑝1

𝐾𝑖𝑝1 + 𝑠1

)

𝐸𝑡ℎ𝑎𝑛𝑜𝑙 𝑝𝑟𝑜𝑑𝑢𝑐𝑡𝑖𝑜𝑛 𝑓𝑜𝑟 𝑥𝑦𝑙𝑜𝑠𝑒

𝛾𝑝2 = 𝑞𝑝𝑚𝑎𝑥2 (𝑠2

𝐾𝑠𝑝2 + 𝑠2

) (1 −𝑝 − 𝑃𝑖𝑝2

𝑃𝑚𝑝2 − 𝑃𝑖𝑝2

) (𝐾𝑖𝑝2

𝐾𝑖𝑝2 + 𝑠2

)


𝑑𝑋 = [𝛼𝛾𝑥1 + (1 − 𝛼)𝛾𝑥2]𝑥 𝑏𝑖𝑜𝑚𝑎𝑠𝑠

𝑑𝑆1 = 𝛼𝛾𝑠1𝑥 𝑔𝑙𝑢𝑐𝑜𝑠𝑒

𝑑𝑆2 = 𝛼𝛾𝑠2𝑥 𝑥𝑦𝑙𝑜𝑠𝑒

𝑑𝑃 = [𝛼𝛾𝑝1 + (1 − 𝛼)𝛾𝑝2]𝑥 𝑒𝑡ℎ𝑎𝑛𝑜𝑙

𝛼 = 0.65

𝑞𝑠𝑚𝑎𝑥1 = 10.9

𝑞𝑠𝑚𝑎𝑥2 = 3.27

𝑞𝑝𝑚𝑎𝑥1 = 5.12

𝑞𝑝𝑚𝑎𝑥2 = 1.59

𝜇𝑚𝑎𝑥1 = 0.31 𝜇𝑚𝑎𝑥2 = 0.1

𝐾𝑠𝑥1 = 1.45 𝐾𝑠𝑥2 = 4.91

𝑃𝑚𝑥1 = 57.2 𝑃𝑚𝑥2 = 56.3

𝐾𝑖𝑥1 = 200 𝐾𝑖𝑥2 = 600

𝑃𝑖𝑥1 = 28.9 𝑃𝑖𝑥2 = 26.6

𝐾𝑠𝑠1 = 6.32 𝐾𝑠𝑠2 = 0.03

𝑃𝑚𝑠1 = 75.4 𝑃𝑚𝑠2 = 81.2

𝐾𝑖𝑠1 = 186 𝐾𝑖𝑠2 = 600

𝑃𝑖𝑠1 = 42.6 𝑃𝑖𝑠2 = 53.1

𝐾𝑠𝑝1 = 6.32 𝐾𝑠𝑝2 = 0.03

𝑃𝑚𝑝1 = 75.4 𝑃𝑚𝑝2 = 81.2

𝐾𝑖𝑝1 = 186 𝐾𝑖𝑝2 = 600

𝐾𝑖𝑝1 = 42.6 𝐾𝑖𝑝2 = 53.1

𝑇𝑦𝑝𝑒 𝑟𝑒𝑎𝑐𝑡𝑜𝑟: 𝐶𝑆𝑇𝑅

𝑇𝑒𝑚𝑝𝑒𝑟𝑎𝑡𝑢𝑟𝑒: 308𝐾


𝑍𝑦𝑚𝑜𝑚𝑜𝑛𝑎𝑠 𝑚𝑜𝑏𝑖𝑙𝑖𝑠

[88]

Fermentation to butanol from glucose

Kinetic model Conversion Conditions Ref

𝐶6𝐻12𝑂6 + 𝐻2𝑂 → 𝐶3𝐻6𝑂 + 3𝐶𝑂2 + 4𝐻2

𝐶6𝐻12𝑂6 → 𝐶4𝐻10𝑂 + 2𝐶𝑂2 + 𝐻2𝑂

𝐶6𝐻12𝑂6 → 2𝐶2𝐻6𝑂 + 2𝐶𝑂2

𝐶6𝐻12𝑂6 → 𝐶4𝐻8𝑂2 + 2𝐶𝑂2 + 2𝐻2

𝐶6𝐻12𝑂6 → 3𝐶2𝐻4𝑂2

0.1554

0.5556

0.0071

0.0217

0.0106

𝑇𝑦𝑝𝑒 𝑟𝑒𝑎𝑐𝑡𝑜𝑟:

𝐶𝑆𝑇𝑅


306𝐾


[101]


𝐶6𝐻12𝑂6 + 6𝑂2 → 6𝐻2𝑂 + 6𝐶𝑂2

𝐶6𝐻12𝑂6 + 1.1419𝑁𝐻3 → 6.055𝐶𝑒𝑙𝑙 + 0.2857𝐶𝑂2 + 2.5714𝐻2𝑂

0.1471

0.0627

𝐶𝑙𝑜𝑠𝑡𝑟𝑖𝑑𝑖𝑢𝑚

𝑏𝑒𝑖𝑗𝑒𝑟𝑖𝑛𝑐𝑘𝑖𝑖

Fermentation to PHB from glucose



𝐵𝑖𝑜𝑚𝑎𝑠𝑠

𝛾𝑥 = 𝜇𝑚

𝑆𝑟

𝑆𝑟 + 𝐾𝑠𝑟

[1 − (𝑆𝑟

𝑆𝑚

)𝑛

] 𝐶𝑥

𝛾𝑠𝑐 = −𝑘4𝛾𝑥 − 𝑘5𝐶𝑥 𝑔𝑙𝑢𝑐𝑜𝑠𝑒

𝛾𝑐 = −𝑘3𝛾𝑥 𝑛𝑖𝑡𝑟𝑜𝑔𝑒𝑛

𝛾𝑝 = 𝑘1𝛾𝑥 + 𝑘2𝐶𝑥 𝑃𝐻𝐵

𝑆𝑟 =𝐶𝑠𝑛 (𝑛𝑖𝑡𝑟𝑜𝑔𝑒𝑛)

𝐶𝑠𝑐 (𝑐𝑎𝑟𝑏𝑜𝑛)

𝜇𝑚 = 0.78ℎ−1

𝐾𝑠𝑟 = 0.29

𝑆𝑚 = 0.3

𝑛 = 0.24

𝑘1 = 0.2604

𝑘2 = 0.0301

𝑘3 = 0.6511

𝑘4 = 4.503

𝑘5 = 0.0001

𝑇𝑦𝑝𝑒 𝑟𝑒𝑎𝑐𝑡𝑜𝑟:

𝐶𝑆𝑇𝑅


303.15𝐾


𝑅𝑎𝑙𝑠𝑡𝑜𝑛𝑖𝑎 𝑒𝑢𝑡𝑟𝑜𝑝ℎ𝑎

[90]

Gasification process

Kinetic model Conditions Ref

Combined cycle

Gasification based on stoichiometric approach using

free Gibbs energy minimization method taking into

account components as CH4, CO, CO2, H2O, NOx,

SOx, N2O, O2, N2

Reactor type: gasified

PBR to 60bar

[132],

[133]

B. Annex: Analysis of the statics for the furfural synthesis by reactive distillation

Furfural is a well-known platform chemical derived from lignocellulosic biomass to produce

resins, pharmaceuticals, agrochemicals and biofuels [104], [123]. In order to overcome the

concern related to the separation of the furfural from the aqueous solution produced after

the biomass digestion, numerous investigative work have been performed to assess the

application of reactive distillation (RD). Due to the presence of an azeotrope of minimum

boiling several concerns may exist related with the separation of furfural. For that reason

RD should be analyzed in depth for this particular mixture to generate optimal flow sheets

to ensure not only the required product quality, but also to provide savings in capital and

energy costs and to keep environmental safety.

As consequence, RD is analyzed as an interesting alternative to isolate the furfural from

the mixture. RD has remarkable characteristics because of the mass selective exchange,

which offers positive influence in chemical transformation. Besides, presence of chemical

reaction to certain conditions can "break up" the azeotropes [139]. The thermodynamic

topological analysis (TTA) has been applied as a tool that quantitatively predicts the

thermodynamic possibilities and limitations of the operation. When the reaction is taken into

account the analysis is called “analysis of the statics” and as a final point, alternative

separation sequences can be investigated and compared in order to select the best one

[140], [141].

Methodology

Static analysis was used to select the limit steady states (LSS) which represent the

maximum conversion and selectivity due that they are cataloged according to optimization

criteria as the most important in the schemes in these processes. The procedure of the


analysis is cited by Pisarenko et al. 2001 and López & López 2003). The chemical reaction

is the dehydration of xylose (X) to produce furfural (F) and water (H2O) according to

equation (1).

𝐶5𝐻10𝑂5 → 𝐶5𝐻4𝑂2 + 𝐻2𝑂 (1)

𝑋𝑦𝑙𝑜𝑠𝑒 → 𝐹𝑢𝑟𝑓𝑢𝑟𝑎𝑙 + 𝑊𝑎𝑡𝑒𝑟

Table B-1 shows the boiling temperatures at atmospheric pressure of the compounds

involved. The system has one azeotrope and their composition and boiling temperatures

are shown in table 2.

Table B-1 Boling temperatures of all compounds involved.

Compound Xylose Furfural Water

Boling point (ºC) 301.78 161.35 100.02

Table B-2 Conditions of the azeotrope of the system.

Azeotrope Boiling point (ºC) Composition

X F H2O

F- H2O 97.68 0.000 0.0938 0.9062

Static analysis

Analysis of the structure of the distillation diagram to the reactive system

Figure B-1 shows the separatriz of second order and the phase diagram of the system from

information indicated on tables B-1 and B-2. The geometric separatriz of the ternary system

is a projection of the geometry limiting of the ternary system X – H2O. Separatriz of second

order does not represent thermodynamic limitations. Blue lines represent the residue

curves which are above and below to the separatriz formed by the azeotrope F - H2O.

Figure B-1 indicates that only exist one distillation region and the residue curves begin in

the azeotrope F – H2O and end in the X point.

Annex B: Analysis of the statics for the furfural synthesis by reactive distillation 147

Fixed points characterization and subregions of distillation

From the information of figure B-1 the fixed point characterization was made and is shown

in table B-3. For both cases, direct and indirect separation exist one subregion of distillation

and are present in table B-4.

Figure B-1 Separatriz of second order and phase diagram of system

Table B-3 Clasification of the fixed points of the system.

Fixed Point X F H2O Az H2O-F

Type Stable node Saddle Saddle Unstable node

Table B-4 Subregions to direct and indirect separations.

Direct separation Indirect separation

Az F - H2O – F – X Az F - H2O - H2O - X

Chemical interaction and reaction lines

Chemical interaction line form depending on the stoichiometric reaction. For furfural

production chemical interaction line is shown in Figure B-3. Direction of reaction lines is

given by the reaction pole as shown equation (2) where L1 is the necessary distance to find


the pole, L2 is the distance from the stoichiometric feeding to the point of product formation,

NP is the number of produced moles and NR is the number of reactant moles.

𝐿1 = 𝐿2

𝑁𝑃

𝑁𝑅 − 𝑁𝑃 (2)

Case 1 When the reaction line is below the azeotrope

Figure B-2 Chemical interaction and reaction line, case 1.

Case 2 When the reaction line is above the azeotrope

Figure B-3 Chemical interaction and reaction line, case 2.


Results and Discussion

Case 1. Limit steady states (LSS)

The reaction line for case 1 is built by four pseudoinitial compositions considering the direct

separation as the most important because the furfural is interest product. P/W is calculated

for the type separation, reaction line and pseudoinitial composition. LSS for direct

separation is shown clearly in table B-5 and figure B-4 (marked by S1).

Table B-5 LSS for direct separation (pseudoinitial compositions and dependence P/W) case 1.

Initial composition Pseudoinitial composition P/W

X H2O F X F H2O

0.08 0.92 0

0 0.03 0.05 0.07

0.05 0.03 0.02 0.01

0.95 0.94 0.93 0.92

1.2 0.67 0.28 0.12

Figure B-4 P/W in function of pseudoinitial compositions of furfural, case 1.

Case 2. Limit steady states (LSS)

The reaction line for case 2 is built by five pseudoinitial compositions considering the direct

separation as the most important because the furfural is interest product. P/W is calculated

for the type separation, reaction line and pseudoinitial composition. LSS for direct

separation is shown clearly in table B-6 and figure B-5 (marked by S1 and S2).

0

0.4

0.8

1.2

1.6

0.00 0.02 0.04 0.06

P/W

Pseudoinitial composition of furfural

S1


Table B-6 LSS for direct separation (pseudoinitial compositions and dependence P/W) case 2.

Initial composition Pseudoinitial composition P/W

X H2O F X F H2O

0.4 0.6 0

0.020 0.044 0.056 0.054 0.069

0.211 0.141 0.109 0.095 0.074

0.769 0.815 0.835 0.851 0.857

7.25 14.0 15.0 14.0 4.25

Figure B-5 P/W in function of pseudoinitial compositions of furfural, case 2.

Feasible steady states

Case 1

In this case only one steady state is feasible with a maximum conversion. Figures 5 and 6

present the trajectory and separation scheme for the steady state. The trajectory is not

developed in the simplex concentracional completely for this reason the furfural obtained

in distillate made is not totally pure.

0

2

4

6

8

10

12

14

16

18

0 0.05 0.1 0.15 0.2 0.25

P/W

Pseudoinitial composition of furfural

S1 S2


Figure B-6 Limit stable state (S1) and technologic scheme, case 1.

Case 2

Figure B-7 Limit stable state (S1) and their possible trajectories, case 2. Technologic scheme

trajectory 1.

The steady stable feasible S2 has a maximum conversion. The trajectory and balance line

have an overlap which leads to the tower-packing is possible from geometrical point of view

but physically is not possible because in this zone trajectory there is not presence of

reagent.


Figure B-8 Limit stable state (S2) and technologic scheme, case 2.

The scheme obtained in the case 2, LSS S1 and the trajectory 1 is compared with the

diagram shown in the figure B-9 published in the patent "Process for the production of

furfural US 20130172583A1" indicating that the analysis made in this study can arrive to a

successful approach for this technological configuration.

Figure B-9 Scheme of process presented in the patent US 20130172583A1 [142].


Conclusions

This analysis shows that short-cut based on thermodynamics, specifically in topological

thermodynamics are a powerful and essential tool before of design and even experiment

with reactive distillation towers, note for example that the cited patent was almost certainly

the work of many years and here by a simple method gets to establish which is the

technological diagram should be proposed to carry out this process.

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