Catalytic Properties of Biochar forChemical Synthesis

Jim Kastner, Joby Miller, Rick Ormsby (Biological and Ag. Engineering Dept.)Jason Locklin, Kristen Fries (Chemistry and FOE)

andDown to Earth Energy, Monroe GA

IBE 2010 Biofuels/Biomaterials Conference March 4-7th, 2010Cambridge, MA

Research Objectives

• Develop value added products from agricultural and forestry residues

• Develop catalysts from the thermochemical biorefinery

• Develop carbon supported catalysts

– Convert biomass (e.g., peanut hulls) into a functional carbon

• Attach catalytic functional groups to carbon surface

• Attach acid and basic functional groups

• Produce solid acid and base carbon supported catalysts

Research Rational

• Develop solid acid and base catalysts for liquid fuel and chemical synthesis (biodiesel production and lignocellulosehydrolysis)

– Recoverable and reusable– Reduce/eliminate pollution

• Current catalysts (H2SO4, sodium methoxide) end up as waste

– More stable, less expensive then current solid catalysts– Made from renewable biomass – Made from a thermochemical biorefinery

Models for Catalyst Formation from Biochar via Biomass Pyrolysis

Toda et al., Nature 438, 10 (2005) 178 – Synthesized via sulphonation with 96% H2SO4 or fuming sulfuric for 15 h

Hardwood Hemicellulose

Cellulose

Pyrolysis

400-500oC, N2

Depolymerization

Volatilization

Cracking

Dehydration

Rearrangment

Sulfonation

99% H2SO4, 20 ml/12.5 g char, mixed, decanted

Heated at 100-250oC, 12-18 hO

OHO S

O OHS

O

Formation of Sulfonate Groups on Aromatic Surface Structure of Char

Acidic

Lignin

Introduction

Biodiesel Application

Solid Catalysts for Biodiesel• Problems with Current Biodiesel Process

– Feedstock’s too expensive, currently can’t use high FFA feedstocks, competition with food

– Less expensive feedstocks contain high level of FFA’s• Waste Oils, Rendered Fats and Oils

– Possible conversion of free fatty acids (FFAs) to methylesters• 1 fatty acid + 1 methanol → 1 fatty acid methylester + 1 H2O• Not possible with current liquid homogeneous catalytic systems

– Current catalysts (liquids) end up as waste

– Can’t use cheaper feedstock’s due to presence of FFA’s• Free fatty acids, such as palmitic or stearic acid• FFA’s create soap if used with base catalyst

– Solid acid and base catalysts, potential solution• Recoverable and Reusable• Can treat high FFA feedstock • Eliminates waste• Potential continuous process

Advantages of Solid Carbon Catalysts

• Stable under acidic and basic conditions

• Stable at high temperature (200-300°C)

• Active material (e.g., acidic functional groups) can be finely dispersed throughout the carbon structure

• Renewable carbon source can be used to generate the active carbon– Use biochar generated from pyrolysis or thermochemical

platform

• Non-polar nature of the support matrix may prevent adsorption of polar molecules (e.g., water or glycerol) that can deactivate the catalyst in transesterification/esterification of lipids

• Can have very high surface areas – 500 to 1500 m2/g

Experimental Methods

Biochar Generation and Functionalization

Solid Acid Catalyst from Biochar• Biomass Sources

– Pelletized peanut hulls and pine, and pine chips

• Pyrolyzed in batch reactor – 400, 500, and 600°C– 2°C/min– 30-40 min holding time at temperature set point

• Biochars characterized– pH, surface area, DRIFT, ATR, some SEM– CHNS and elemental analysis

• Solids collected, acid/base functionalized

0

100

200

300

400

500

600

700

0 60 120 180 240 300 360 420 480 540 600

Tem

pera

ture

(C)

Time (minutes)

Temperature Profile -Clean Pine Chips 400C Pyrolysis

Mass Flow Controller

N2 Sweep Gas Tank

Biomass Pyrolysis ReactionInternal Reactor/External

FurnaceCondensation Unit

Three Condensers in Series in and Ice Bath

Permanent Gases – CO, CO2, H2

Bio-oil Collection

(1)

(2)

(3)(4)

Solid Acid Catalyst from Biochar• Acid Functionalization – Sulfonation

• Concentrated sulfuric acid

• Pelleted biochar ground, screened 4-12 mesh

• 12.5 g treated with 20 ml, 99% H2SO4

• Heated in ceramic crucible in a muffle furnace– 100, 150, and 250°C for 12 hours

• Cooled, washed with DI water until rinse constant pH, and dried overnight (110°C)

• Anticipated functional group: -C-SO3H

Solid Acid Catalyst from Biochar• Acid Functionalization

– Ozone Treated• 25 g biochar, room temp.• 1 L/min, 33 mg/m3 ozone, 6 hours• Anticipated functional group – carboxylic acid, -COOH

(1)

(2)

(4)

(5)

(6)

Oxygen

(3)

• Ozone Treatment• 1 - pure oxygen input• 2 - mass flow controller• 3 - ozone generator• 4 - packed bed column• 5 - ozone detector• 6 - exhaust

Mawhinney and Yates, Carbon 39 (2001) 1167–1173

Tessonnier et al., Angew. Chem. Int. Ed. 2009, 48,6543 –6546 – functionalizing CNT‘s with amines

Solid Base Catalyst from Biochar

• Base Functionalization – Similar Process to Acid

– Low temperature pyrolysis• 500°C• 2°C/min• 30-40 min holding time at temperature set point

– Pretreated with Ozone or HNO3• Adds carboxylic acid groups to surface

– Treat with a strong organic base • Organic base attached to carboxylic acid groups

» Ethylenediamine (EDA), » 4-aminophenoxide (4-AP)

• Heated, 65-110°C• Holding time, 22 h – 3 days

– Organic base decanted, catalyst washed with MeOH (8-10 X)– Heated/dried at 100°C overnight

NH2

NH2

O-NH2 Na+

EDA

4-AP

Solid Acid Catalyst Results

• Biochars (non-functionalized)

• Low surface area, 2-4 m2/g• Variable pH, but basic• DRIFT analysis – Aromatic and aliphatic groups

• Acid functionalized biochars - DRIFT Analysis • Ozone Treatment

• Non-polar structure eliminated• Carboxylic acid groups formed

• Sulfonation• A large peak at 1750 cm-1, indicative of a carboxylic acid group

appeared in the sulfonated peanut hull chars generated at 400 and 500°C

• SO3H groups identified by DRIFT and ATR • Acid density increased with decreasing pyrolysis

temperature and sulfonation temperature

Results

Biochar CharacterizationSolid Acid Esterification Tests

Solid Acid Catalyst CharacterizationPhysical and chemical characteristics of biochar used to develop catalysts

ND - Not Determined, NP- Not Performed, AC – Activated Carbon, BDL – Below detection limit of 2 ppm*, Measured by Down to Earth Energy

Materials

Properties

Activated*

Carbon

(Lignite Coal)

Peanut Hull Char

(400°C)

Peanut Char

(500°C)

Pine Chip Char

(400°C)

Pine Chip Char

(500°C)

Generation Process Steam Pyrolysis-N2 Pyrolysis-N2 Pyrolysis-N2 Pyrolysis-N2

Reactor/Residence Time Unknown Batch/40min Batch/40min Batch/40min Batch/40min

pH 4.6 10.5 10.1 7.55 8.3

Surface Area, m2 g-1

O3 treated, 30 min

506 ± 34

494 ± 57

NM

ND

3.2±0.6

ND

3.8 ± 0.14

ND

2.75 ± 0.2

ND

Pore Volume (ml g-1) 0.55 ± 0.005 NM 0.004± 3e-4 ND ND

Selected Elements

(ppm or mg kg-1)

Mean Mean Mean Mean Mean

Cu ND 16 18 25 9

Mn “ 116 157 274 258

Mo “ 4.8 < 1 < 1 < 1

Ni “ 2.3 3.95 < 2 < 2.91

Fe “ 1000 1094 150 50

Ca “ 4620 4,090 1710 1850

K “ 15,200 20,700 1450 1450

Mg “ 2,190 2,478 600 590

Wavelength, cm-1500 1000 1500 2000 2500 3000 3500

PCC 400C

PCC 400C, O3

DRIFT AnalysisDRIFT analysis of pine chip char(PCC) chars generated at 400 °Cvia pyrolysis, pre-oxidized withozone.

DRIFT analysis in the Kubelka-Munk mode, the signal rangedfrom 0-0.25 for the ozonatedchars, and 0-6 for the non-treated chars (i.e., biochar).

Biochar1000-1500 and 3100-3500 cm-1,

•C-O, ethers•C-H, aliphatics

1600 cm-1, C=C olefinic2900 cm-1, C-H aromatic

Ozonated Biochar

1750 cm-1, C=O

PCC 400C, 100S

Wavelength, cm-1

1000 1500 2000 2500 3000 3500

PCC 400C - Control

DRIFT Analysis

Wavelength, cm-1

500 1000 1500 2000 2500 3000 3500

400C PCC, 100C Sulfonation

500C PPC, 250C Sulfonation

500C PHC, 250C Sulfonation

ATR Analysis

Sulfonated Biochar

1750 cm-1, C=O600 cm-1 , C-S

1040 cm-1 , SO31200 cm-1 , S=O1377 cm-1, O=S=O

Sulfur Analysis of Functionalized Biochar

Catalysts Carbon, % Nitrogen,% Sulfur, % SO3H Density

mmol/ga

PHC-500P 64 ± 1.7 2.0 ± 0.30 0.14 ± 0.05

PCC-400P 65 ± 0.38 1.8 ± 0.6 0.10 ± 0.03

PCC-400P-100S 56 ± 0.30 0.24 ± 0.01 3.7 ± 0.08 1.12 ± 0.02

PPC-400P-100S 62 ± 0.76 0.40 ± 0.08 1.2 ± 0.11 0.34 ± 0.01

PCC-400P-100S 58 ± 0.23 0.39 ± 0.13 2.30 ± 0.08 0.69 ± 0.006

PCC-400P-150S 46 ± 17.4 0.31 ± 0.03 1.39 ± 0.35 0.41 ± 0.08

PCC-400P-250S 62 ± 20.5 0.43 ± 0.23 0.86 ± 0.30 0.24 ± 0.06

PHC, Peanut Hull Char; PCC, Pine Chip Char; PPC, pine pellet charP, Pyrolysis Temperature; S, Sulfonation Temperature

a, calculated from sulfur content assuming all S atoms are in the –SO3H form with baseline sulfur content subtracted

Catalytic Testing/Screening

• Esterification of Palmitic and Stearic Acid

• Small scale batch reactor system (Reacti-Therm, Pierce –Thermo Scientific)• Used for Screening Catalysts

• Known amount of catalyst, typically 0.2 g used

• 5 ml total volume

• Known initial mass of palmitic (C16-saturated FFA) or stearic (C18-saturated, both at 200-500 ppm) and methanol (4 ml).

• Mixture was then heated at 55-60°C and sub-samples taken as function of time to determine the formation of methylesters via GC analysis

• Control reactions consisted of the untreated char (negative control) or use of HCl (positive control)

Catalytic Testing

• Fractional removal of palmitic or stearic acid measured

• Based on the defined initial concentrations of the FFA's

• Maximum theoretical amount of methylester that could form,

• and the concentration of the methylesters of the FFA's that formed during the catalytic reaction

• Measured by GC/FID or GC/MS

Catalytic Testing• All sulfonated chars catalytically active for esterification of

palmitic and stearic acid with methanol

• Chars treated with ozone only were not active (too weak an acid)

• Sulfonated biochars - typically complete (∼90-100% conversion) within 30-60 minutes at 55-60°C

• Of the synthesized catalysts, 400°C pyrolyzed pine chip char, sulfonated at 100°C, resulted in the highest reaction rate and lowest reduction in conversion (or deactivation) when reused multiple times

• Catalytic activity declined with reuse (without regeneration)• Heating catalyst at 125°C allowed reuse without catalytic

decay (95-100% conversion up to 7 times)

• Demonstrated esterification of FFA’s (11-14%) spiked in poultry fat • 70-90% conversion in 2 h at 65°C

Catalytic Testing

Comparison of esterification catalytic activity between sulfonated pelletized peanut hull and pine biochar (500°C pyrolysis, sulfonation250°C). Reactions conditions were 200 ppm palmitic or stearic acid in methanol (5 ml), 0.20 g char, and 58°C.

Palmatic Acid Esterification, Pine Pellet Biochar

Time, min0 20 40 60

Frac

tiona

l Con

vers

ion

0.0

0.2

0.4

0.6

0.8

1.0

1.2

Ozonated and Sulfonated SulfonatedOzonated OnlyUntreated Biochar

Palmatic Acid Esterification, Pine Pellet Biochar

Time, min0 20 40 60

Frac

tiona

l Con

vers

ion

0.0

0.2

0.4

0.6

0.8

1.0

1.2

Ozonated and Sulfonated SulfonatedOzonated OnlyUntreated Biochar

Palm itic Acid Esterification, Peanut Hull Biochar

Time, min0 20 40 60

Frac

tiona

l Con

vers

ion

0.0

0.2

0.4

0.6

0.8

1.0

1.2

Ozonated and Sulfonated SulfonatedOzonated OnlyUntreated Biochar

Stearic Acid Esterification, Peanut Hull Biochar

Time, min0 20 40 60

Frac

tiona

l Con

vers

ion

0.0

0.2

0.4

0.6

0.8

1.0

1.2

Ozonated and Sulfonated SulfonatedOzonated OnlyUntreated Biochar

Catalytic Testing

Comparison of esterification catalytic activity between different sulfonated biochars. Reactionsconditions were 500 ppm palmitic and stearic acid, 0.50 g char, and 58°C for 1 hour. Catalystswere recovered, rinsed with methanol and reused without further treatment.

400C-P, is 400°C pyrolysis100C-S, is 100°C sulfonation temperature

Catalytic Testing - Reuse

Effect of heating the acid catalyst in heptane (left, 250°C) or heating only (right, 125°C) onesterification activity during reuse. The period before A indicates methanol rinsing only, after Aindicates heptane rinsing following by heating at 250°C, and after B represents heptane rinsingfollowed by heating 125°C (left). The catalyst was generated from pine chip biochar pyrolyzed at400°C and sulfonated at 100°C for 12 h. All reactions were performed at 60°C with 0.5 g ofsulfonated char for 30 minutes. Note – Regeneration treatment was not performed on reuse of thechar catalyst from treatments 1 to 7 (top, left).

• Theory – water adsorption inhibiting catalyst • Tested heating recovered solid acid catalyst for reuse

Catalytic Testing – Poultry Fat• Larger scale batch reactors

• 50 ml volume

• Collected local rendered poultry fat

• Spiked with palmitic and stearic acid – 11.5% FFA’s• 36 g fat, 2.2 g palmitic , 2 g stearic• 33 ml of methanol

• 2g of acid functionalized biochar used• Used best char from previous studies• Pine chip char - Pyrolysis at 400°C, sulfonation at 100°C

• Heat at 65°C for 2 hour

• Measured FFA’s at end

• 70-99% conversion of FFA’s in Poultry Fat (triplicate)

Catalytic Esterification Comparison to Literature

Catalyst Fat or Oil MeOH:FFA

Molar Ratio

% FFA’s

(w/w)

% Catalyst

(w/w)

% Conversion Residence Time,

Temp.

(h, °C)

Conversion

Measurement

Method

PCC-400P-100S Poultry Fat 39:1 13.9 5.6 49 ± 7 2, 65 GC/FID

98 ± 0.03 2, 65 TAN*

55:1 10.5 3 81 ± 16 2, 65 GC/FID

101.6 ± 0.02 2, 65 TAN*

Soybean Oil 39:1 13.5 5.6 53 ± 6.5 2, 65 GC/FID

Pyrolyzed-Starcha Waste Oil 20:1 27.8 10 60 2, 80 GC/FID

Amberlyst BD20b Trap Grease 6:1 50 20 62 2, 80 TAN

Pyrolyzed-Glucosec Palmitic-Soybean Oil 6:1 10 2 20 1, 60 1H-NMR, Acid

Titration

Dowex 550Ad Oleic- Sunflower 6:1 10.7 2.3 80-90 2, 55 Acid Titration

*, Conversion to methyl esters based on measurement of free fatty acids using potentiometric titration (ASTM 664), TAN is total acid numbera, Lou et al., 2008 – % conversion for esterification of FFA’s and transesterification of triglyceridesb, Park et al., 2010c, Mo et al., 2008 - solid acid, carbon catalyst via glucose impregnation of Amberlite XAD1180, followed by pyrolysis and sulfonationd, Marchetti et al., 2007 – ethanol used in esterification

Free fatty acid conversions (palmitic and stearic acids) to methyl esters in rendered poultry fat andsoybean oil using a solid acid carbon catalyst (400°C pine chip biochar, sulfonated 100°C) andcomparison with literature (65°C, 2 h, 2.0 grams of biochar catalyst).

Results

Biochar CharacterizationSolid Base Transesterification Tests

Solid Base Catalysts • Base Functionalization – Similar Process to Acid

– Low temperature pyrolysis• Used pine and peanut hull pellets• 500°C• 2°C/min• 30-40 min holding time at temperature set point

– Pretreated with Ozone or HNO3• Adds carboxylic acid groups to surface

– 2 Different strong organic bases attached

– Total of six solid base catalysts generated– 2 Biochars - peanut hull and pine pellets– 2 pretreatments - HNO3 treated (minus pine pellets), Ozone

treated – 2 organic bases or EDA and 4-aminophenoxide

Solid Base Catalyst Characterization

• DRIFT Analysis

• O3 and HNO3 treatment generated –COOH, 1750 cm-1

• Reaction with organic bases indicated amide bond formation• Band at 1750 cm-1 shifted to 1600-1650 cm-1

PHC 500C,HNO3

Wavelength, cm-1

500 1000 1500 2000 2500 3000 3500

PHC 400C

PHC 500C, HNO3, EDA

Wavelength, cm-1

500 1000 1500 2000 2500 3000 3500

PCC 400C

PCC 400C, O3, EDA

PCC 400C, O3

Pine Chip BiocharDRIFT Analysis

Peanut Hull BiocharDRIFT AnalysisEDA Functional Biochar

1750 cm-1, C=O1650 cm-1, C=O in amide

Solid Base Catalytic Testing/Screening

• Transesterification of glyceryl tridodecanaote

– Small Batch Reactors• 0.5 g catalyst, 2 ml • 500 ppm each of n-hexadecane and methyl

pentadecanoate internal standards, • and glyceryl tridodecanoate in anhydrous methanol

– Agitation at 300 rpm, 65°C, 3 h

– Quench reaction and sample for GC/FID or GC/MS to quantify dodecanoate methylesters

– Base functionalized chars resulted in 30-100% conversion of glyceryl tridodecanoate and formation of methylesters

+3 methanol (base catalyst)

+

3

Solid Base Catalytic Screening

• Transesterification of glyceryl tridodecanaote

Biochar Pretreatment Base pH %ConversionPeanut Hull HNO3 4-AP 9.56 100Peanut Hull Ozone 4-AP 9.63 100Peanut Hull HNO3 EDA 10.32 30Peanut Hull Ozone EDA 11.15 100

Solid Base Catalytic Screening

• Transesterification of glyceryl tridodecanaote

Biochar Pretreatment Base pH %Conversion

Pine Pellets Ozone 4-AP 9.50 79

Pine Pellets Ozone EDA 10.49 100

Solid Base Catalytic Testing

• Selected Base Functional Peanut Hull Biochar

• Transesterification of soybean oil

• Catalysts Tested• Peanut hull biochar, ozone, EDA• Peanut hull biochar, ozone, 4-AP

• Batch Reactor System• 8 g of catalyst• 41 g of soybean oil, 41 g of methanol• Stirred at 65°C, 3 h• Reaction mixture filtered, 2 phases• Bottom layer, biodiesel, collected• Analyzed by

• GC/FID - ASTM Method D6584-07• Potentiometric titration for total acids using ASTM

Method 664-07• Closed cup flash point using ASTM Method D93-07

Solid Base Catalytic Testing

• Transesterification of soybean oil

• Compared to Sodium Methoxide catalyst (traditional method)

• Complete conversion of soybean oil to biodiesel using peanut hull, ozone pretreated, 4-AP attached catalyst• Low to no measureable conversion using EDA catalyst

• Results comparable to sodium methoxide catalyst

Samples of soybean oil (A), biodiesel from 4‐AP biochar catalyst (B), and biodiesel from sodium methoxide conventional 

methodology (C).

A B C

Solid Base Catalytic Testing GC/FID Results

Diglyceride and TriglyceridesSoybean Oil

Solid Base – 4AP, Catalyst

C16, C18 methylesters or biodiesel

Sodium Methoxide Catalyst

C16, C18 methylesters or biodiesel

Catalytic Transesterification Comparison to Literature

Base Catalysts MeOH:Oil

Molar Ratio

T

°C

% Catalyst

(w/w)

% Conversion

(Time, h)

Catalyst

Treatment/Symbol

Conversion

Measurement

Method

EDA 8.5:1 65 8.9 0.0 (3) PHC-O-EDA-400-B GC/FID

4-AP 39:1 65 8.9 100 (3) PHC-O-4AP-500 GC/FID

Na-Methoxide ? 65 ? 100 (3) GC/FID

CaOa 12:1 65 8 95 (3) 2 % water GC/FID

CaOb 27:1 25 ? 99 (24) Nanocrystalline 1H NMR

Ca(OH3)2c 2:1 65 4 95 (2) GC/FID

Aminated Carbon

Nanotubes or CNT d

12:1 60 ? 65 (3) or

77 (8)

Triethylamine

attached CNT

?

Catalytic activity of ozone oxidized biochar, functionalized with EDA and 4-aminophenoxide, as base catalysts for transesterification of triglycerides in soybean oil (except where noted)

at 65°C for 3 hours using 8.5 grams of biochar catalyst and comparison with literature.

*, conversion to methyl esters based on measurement of free fatty acids using potentiometric titrationa, Liu et al., 2008b, Reddy et al., 2006c, Liu et al., 2008bd, Villa et al., 2009, substrate used was glyceryl tributyrate

Lignocellulose HydrolysisUsing Solid Acid Catalysts

Biochemical Refinery Application

Cellulosic Ethanol Application

• Key Concept – Replace Enzymes with Solid Acid Carbon Catalyst

– Hydrolyze cellulose and hemicellulose to sugars (e.g., glucose and xylose), then ferment or catalytically convert to liquid fuels (e.g., ethanol or isobutanol) or chemicals (lactic acid, HMF)

– Enzymes are expensive, currently unrecoverable, and sensitive to inhibitors

– Limited environmental conditions• Near neutral pH • Temperature typically < 40-50°C

– Enzymes sometimes have a much lower reaction rate compared to chemical catalysts

Cellulosic Ethanol Application

• Solid Acid Carbon Catalysts Generation

– Same method, only difference,• Biochar generated from pyrolysis crushed to a fine powder before

sulfonation to generate acid catalyst

– Biomass: Peanut Hulls Pellets, Pine Chips

– Pyrolysis at 400°C

– Sulfonated at 100°C, 12 h (99% H2SO4)

Lignocellulose Hydrolysis

• Catalytic Testing

– Small batch reactors – 25 ml Pyrex Erlenmeyer flasks, bottles or 10 ml high pressure tubes

– Model Compounds Used: • Cellobiose for cellulose, Xylan (birch wood and locust bean gum) for

Hemicellulose

– 10 g/L Cellobiose, 1 and 10 g/L Xylan– 30, 60, 90, and 120°C at various residence times

– Reactions performed at 30, 60 and 90°C performed in a shaker/water bath under agitation

– Reactions at 120°C were performed in an autoclave without agitation

• Subsequently moved to a reactor/stirrer/hot plate with high pressure tubes

– Cellobiose, glucose, and xylose measured using HPLC with RI detector and standards

Cellulosic Ethanol Application• Catalytic Results - Cellobiose

– Significant activity not measured until 90°C

Effect of temperature on the hydrolysis of cellobiose (10 g/L, 1 g catalyst) using sulfonated pine biochar.

Cellulosic Ethanol Application

• Catalytic Results - Cellobiose

– Solid acid catalyst generated from pine chips appeared to have the highest activity

– Thermal hydrolysis did not occur (top figure)

– Unknown compound did form in the catalytic systems

• attributed to a leachate from the biochar, since this same unknown appeared in reactors with the sulfonated biochar only (not shown)

Cellulosic Ethanol Application

• Catalytic Results - Cellobiose

– Catalysts used at 120°C were recovered (by filtration, but not washed) and reused

– The reused solid acid catalysts were active for cellobiose hydrolysis

• decline in fractional conversion, most notably for the peanut hull biochar

Catalysts Peanut Hull Biochar

Pine Chip Biochar

Time, hrs X Y, g/g X Y, g/g0 0 0 0 03 0.64 ± 0.02 0.66 ± 0.024 0.93 ± 0.084 1.0 ± 0.0943

(Recovered/Reused) 0.12 ± 0.08 0.45 ± 0.023* 0.85 ± 0.13 0.83 ± 0.3

Catalytic hydrolysis of cellobiose (10 g/L, 10 ml working volume) using solid acid catalysts (1 g biochar) at 120°C. X is the fractional conversion of cellobiose and Y is the glucose yield.

*carryover from solid catalyst

Chemical Synthesis• Catalytic Results for Control

Char

– Non-sulfonated biochar used as control

– Did not anticipate a reaction

– Cellobiose apparently hydrolyzed

– Unknown products produced

– Base peanut hull char has pH of 10.7 compared to 7.8 for pine chip char

– Suggests the possibility of chemical synthesis using solid base carbon catalyst

• Lactic acid from glucose • Glucose to fructose HPLC chromatograms of control reactions, pine chip biochar

with cellobiose (top) and untreated peanut hull biochar (bottom).

Chemical Synthesis• Apparent Isomerization

Activity for Base Char

Glucose ↔ Fructose

– Glucose or Fructose Added, 10g/L

– 1 g char, 120oC, 5 h

– Formed equilibrium mixture of glucose and fructose

– More recent data indicate conversion complete (equilibrium reached) within 1 h or less (potentially faster)

0

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20000

0 2 4 6 8 10 12 14 16 18 20

RI

Signal

Time, min

Peanut Hull CharGlucose 10 g/L - 120C 5 h

Unknowns

Fructose

Glucose

0

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8000

10000

12000

14000

16000

0 2 4 6 8 10 12 14 16 18 20

RI

Signal

Time, min

Peanut Hull CharFructose 10g/L 120C 5h

Unknowns

Fructose

Glucose

Hardwood Hemicellulose Hydrolysis

– Birch wood xylan used as model

– Solid Acid Catalysts (1 g) used at 120°C

– After 5 hours Xylose formed

– Xylan solution (1 g/L) turned from cloudy/brown to light clear brown

– Pine chip biochar catalyst: 60% conversion of xylan

– Peanut hull biochar catalyst: 40% of conversion xylan

• Based on assumption that 1 g/L of xylan forms 1 g/L of xylose and HPLC analysis for xylose

0

500

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2000

0 2 4 6 8 10 12 14 16 18 20

RI S

igna

l

Time, min

Xylan Control 120C, 5 hr(1 g/L)

0

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2000

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5000

0 2 4 6 8 10 12 14 16 18 20

RI S

igna

l

Time, min

PHC- Xylan 120 5 hr

Unknown

Xylose

0

2000

4000

6000

8000

0 2 4 6 8 10 12 14 16 18 20

RI S

igna

l

Time, min

Pine Char - Xylan 120 5 hr

Unknown

Xylose

Unknown

0

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0 5 10 15 20 25

R I

Sign

al

Time (min)

4 hr - PC 400 - Xylan 10 g/L, 120 oC

Xylose

0

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R I

Sign

al

1hr - PC 400 - Xylan 10 g/L, 120 oC

Hardwood Hemicellulose Hydrolysis

• 10 g/L Xylan (birchwood)• 1 g solid acid catalyst• Sulfonated pine chip biochar

Xylose

0

1

2

3

4

5

6

7

0 5 10 15 20 25 30

Con

cent

ratio

n (g

/L)

Time (hrs)

Hardwood Hemicellulose Hydrolyis Using Solid Acid Catalyst - 120 oC, Trial 1

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24 hr - Control - Xylan 10 g/L, 120 oC

Softwood Hemicellulose Hydrolysis

• Model for softwood hemicellulose

– Galactomannan– β-(1,4)-D-mannose units– Every 4 units, 1 galactose side

substituted• 10 g/L xylan (locust bean gum)• 1 g solid acid catalyst, 10 ml• Sulfonated Pine Chip Biochar• 120°C, 5 h

Mannose

Galactose

05000

100001500020000250003000035000

0 5 10 15 20

RI

Sign

al

Time, min

10 hr Control - LBG 10 g/L, 120oC Trial 1

05000

100001500020000250003000035000

0 5 10 15 20

R I

Sign

al

Time (min)

2 hr - PC 400 - LBG 10 g/L, 120oC Trial 1

05000

100001500020000250003000035000

0 5 10 15 20

R I

Sign

al

Time (min)

4 hr - PC 400 - LBG 10 g/L, 120oC Trial 1

Conclusions • Demonstrated synthesis of solid acid and base carbon

catalysts from biochar

• Demonstrated feasibility of solid carbon catalysts for biodiesel production

• Cellobiose and xylan hydrolysis using solid acid catalyst demonstrated– Clear potential for use in forest biofinery

• Hemicellulose extraction before pulping and paper and forest product production

• New value added products from biorefinery developed– Generated from agricultural and forestry residues– Generated from renewable biomass resources

• Foundation for carbon catalysis and chemical/liquid fuels– Methanol to dimethylether or DME (a diesel substitute)– Glucose to lactic acid (biodegradable polymer or polylactic acid, PLA)– Glucose and xylose to furfurals– In-line catalytic esterification of bio-oil vapors to stabilize bio-oil

Future Work

• Optimize pyrolysis for catalyst synthesis

• More detailed characterization of biochar and formed catalysts

– Need better understanding of biochar structure before and after functionalization– Correlate structure with pyrolysis conditions and catalytic testing

• Detailed studies on reuse, longevity, and kinetics of reactions needed– Biodiesel synthesis– Cellulose and Hemicellulose hydrolysis– Couple with hot water treatment of biomass for cellulose hydrolysis

• More detailed studies on adding basic functional groups and resultant catalytic activity required

• Expand research on catalytic activity to other products– DME, bio-oil stabilization, glucose and xylose to chemicals