contents€¦ · heterogeneous alternatives are being pursued. in this regard, amine functionalized...

Master of Science in Chemical Engineering - AJ 2017-2018

Goedgekeurde onderwerpen

Contents 16451: Aldol condensation catalyzed by electrospun aminated silica nanofibers ................................. 2

16705: An experimental study of the effect of promoters on the performance of Co-based Fischer

Tropsch catalysts ..................................................................................................................................... 5

17122: Analysing BIG data: QXAS on Ni-Fe catalysts .............................................................................. 7

17232: Automatic generation of microkinetic models for polycyclic aromatic hydrocarbon formation

during pyrolysis of hydrocarbons .......................................................................................................... 10

17287: Computational Fluid Dynamic simulation of heterogeneous catalytic reactors ....................... 13

17191: Computational investigation of penultimate effects in RAFT polymerization .......................... 15

17329: Continuous flow investigation of industrially relevant aldol condensations .................. 18

16709: Design of a Carbon Neutral Process for the Synthesis of Methanol ......................................... 21

17168: Design of Pt-based bimetallic catalyst particles for the catalytic dehydrogenation of propane

............................................................................................................................................................... 24

17804: Designing a novel core-shell structured bifunctional material for CO2 utilization ................... 27

17806: Development of a bifunctional material for CO production from CO2 by catalyst-assisted

combined chemical looping .................................................................................................................. 30

17269: Experimental Heat Transfer Studies in a Hot Flow Vortex Reactor .......................................... 33

17277: Experimental investigation of particle segregation in a Gas Solid Vortex Unit (GSVU) ............ 36

17251: Fast Pyrolysis of Pinewood in the Gas-Solid Vortex Reactor .................................................... 38

17230: Genesys: automatic generation of kinetic models .................................................................... 41

17226: Investigation of biomass fast pyrolysis via pyrolytic degradation of model compounds ......... 44

17285: Kinetic Analysis of Pharmaceutical Reactions: Synthesis of Diphenhydramine ........................ 46

17201: Kinetic modeling of the pyrolysis of lignin model compounds ................................................. 49

17176: Kinetics Simulation in Emission Control: Catalytic Oxidation of Tricholoroethene Plasma

Degradation Products ............................................................................................................................ 51

17233: Large eddy simulation of turbulent reacting flows ................................................................... 54

17219: Mass transfer in a vortex reactor: experimental and theoretical study ................................... 57

17063: Mechanistic study of ethanol oxidation on gold silver catalysts .............................................. 60

16707: Mechanistic study of Fischer-Tropsch synthesis ....................................................................... 62

17803: Microkinetics for methane dry reforming over Fe-Ni-(M)/MgAl2O4 ....................................... 65

17302: Modeling of non-isothermal controlled radical polymerization reactors ................................. 68

17199: Optimization of catalyst composition and reaction conditions for Pt-and Pd-based

(de)hydrogenation processes ................................................................................................................ 70

17266: Process intensification through reactive flow modulation ....................................................... 73

17224: Pyrolysis of cyclic and oxygenated compounds: a combined modelling and experimental study

............................................................................................................................................................... 76

16482: Reaction network size control for the heterogeneously catalyzed conversion of renewable

feeds ...................................................................................................................................................... 78

17274: Reactive CFD Simulations for biomass fast pyrolysis in Gas Solid Vortex Reactors .................. 81

17304: Retrieving intrinsic kinetic parameters using pulsed laser polymerization .............................. 84

16700: Role of promoters in Co-based Fischer-Tropsch synthesis ....................................................... 87

17623: Shedding light on Thin Film Solar Cell Performance through fundamental modelling in SCAPS-

1D and the microKinetic Engine ............................................................................................................ 90

16697: The μ-Kinetic Engine (µKE): towards a versatile tool for complex feed conversion simulation

and parametric identification ................................................................................................................ 92

17060: The role of promoters in copper catalysis ................................................................................. 95

16451: Aldol condensation catalyzed by electrospun aminated

silica nanofibers

Promotor(en): Karen De Clerck, Joris Thybaut

Begeleider(s):

Contactpersoon: Lode Daelemans

Goedgekeurd voor: Master of Science in Chemical Engineering, Master of

Science in Sustainable Materials Engineering

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Probleemstelling:

Aldol condensations are important reactions to create new carbon-carbon

bonds and yield larger and more complex molecules. They are widely used

in the pharmaceutical industry as well as for the preparation of fine

chemicals, perfumes and synthetic flavors. However, an unsustainable

homogenous base catalyst such as NaOH or Na2CO3 is used to catalyze

these reactions. In a search for more sustainable chemical processes,

heterogeneous alternatives are being pursued. In this regard, amine

functionalized silica materials have been proven to be successful catalysts.

In this work, silica nanofibers functionalized with amine groups will be

synthesized and their performance evaluated for the aldol condensation

reaction.

Nanofibrous webs are considered as a novel class

of materials consisting out of very thin fibers with typical diameters below

500 nm. The small diameter gives these materials interesting

characteristics such as a large surface area, a high porosity (> 90%) and

improved mechanical properties compared to the bulk polymer. Currently,

electrospinning is the most efficient technique to produce such nanofibrous

webs from a polymer solution. The solution is fed through a hollow needle

and subjected to an electric field of 10 – 50 kV. When a drop of polymer

solution leaves the needle and enters the electric field, it gets charged. This

leads to a jet of polymer solution towards the collector plate. Before the jet

reaches the grounded collector screen, instabilities occur which stretch the

droplets into fibers. As a result, the solvent evaporates and a web of

nanofibers is obtained on the collector. Recently, we succeeded at UGent

to use this technique for a one-step production of silica nanofibers. These

nanofibers combine the properties of nanofibrous webs (flexibility,

porosity, large surface area) with those of bulk silica (chemical resistance,

temperature stable, mechanical properties, silica surface chemistry).

Program

Based on the activity previously measured on aminated bulk silica

catalysts, a synthesis procedure will be devised for aminated silica

nanofibers. Critical parameters such as the total amount, and distribution,

of amine groups on the surface should be taken into account, as well as

possible restrictions of the electrospinning process and the batch reactor for

the catalytic tests. The considered test-reaction will be the aldol

condensation of 4-nitrobenzaldehyde and acetone. Information obtained

from these catalytic tests will then provide feedback to the catalyst

synthesis steps and lead to improvements.

Doelstelling:

Assessment of the applicability of silica nanofibers functionalized with

amine groups as an effective catalyst for aldol condensation reactions.

Locatie:

Technologiepark 914, 9052 Gent

Website:

Meer informatie op: www.lct.ugent.be

16705: An experimental study of the effect of promoters on the

performance of Co-based Fischer Tropsch catalysts

Promotor(en): Mark Saeys

Begeleider(s):

Contactpersoon: Mostafa Aly

Goedgekeurd

voor:

Master of Science in Chemical Engineering, Master of

Science in de ingenieurswetenschappen: chemische

technologie

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Probleemstelling:

Justification

Over the past decade, the significant increase in demand for cleaner fuels

and chemicals has led to a significant shift from crude oil to natural gas as

the feedstock for chemical industries. This shift involves the use of Fischer

Tropsch (FT) technology, where high molecular weight hydrocarbons are

synthesized from the catalytic hydrogenation of CO using Co-based

catalysts.

The Cobalt catalysts are, almost always, loaded with small amounts of

promoter elements that improve their performance by enhancing the

activity, selectivity, and stability, or a combination of these characteristics.

These effects are, however, only obtained if the promoter is added in the

appropriate manner and with optimum loading. Many elements have been

found to enhance the performance of Co-based FT catalysts, however, the

exact role and/or location of the promoters remains often unclear. In this

study, promoters to be investigated, alone or combination, include

Chlorine, Manganese, and Boron. A comprehensive experimental study of

the effect of these promoters will bring us a step closer to understanding

their role in FT, thus allowing rational catalyst design.

Program

Perform a review of the academic and patent literature on promotors for

Co-based FT catalysts, with a focus on promotors with controversial

effects. The review includes effects of the synthesis procedure and of the

precursors on the catalyst performance.

Synthesize catalysts using various synthesis procedure and characterize the

resulting materials.

Experimentally evaluate and analyse the effect of promotor and promotor

loading on activity, selectivity, and stability.

Doelstelling:

The aim of this thesis is to experimentally investigate synergistic effects of

promoters on the activity, selectivity, and stability of Co-based Fischer

Tropsch (FT) catalysts. Focus will be given to promoters for which

controversial effects have been reported.

Locatie:


Website:


17122: Analysing BIG data: QXAS on Ni-Fe catalysts

Promotor(en): Hilde Poelman

Begeleider(s):

Contactpersoon: Hilde Poelman

Goedgekeurd

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Justification

Methane dry reforming (CH4 + CO2 ↔ 2CO

+ 2H2), with CH4:CO2=1:1, offers the

attractive advantage of obtaining a H2:CO

molar product ratio close to unity. For this

process, Ni has been widely investigated as a

reforming catalyst because of its efficiency,

low cost and high availability. To counter

catalyst deactivation, Fe can be a suitable

promoter to Ni-based catalysts, suppressing

carbon accumulation and increasing catalyst

activity. In order to identify the iron phase

and its role in a novel nickel-iron alloy

catalyst for dry reforming, this Ni-Fe

combination has been examined using Quick-

X-ray absorption spectroscopy (QXAS) at

both the Ni and Fe K edge. XAS allows to

examine the local environment around Fe and

Ni in these bimetallic catalysts, even during

Figure 1: XANES spectra of

10wt%Ni-

10wt%Fe/MgAl2O4 at (a)

Fe-K and (b) Ni-K edge

during H2-TPR.

treatment or reaction (alloying,

decomposition and dry reforming), see figure

1.

As faster measuring techniques are developed

and characterization methods are often

combined with each other, the result of one

measurement can soon encompass several

MB of data. This is for instance the case for

QXAS measurements, where full XAS

spectra are recorded in a matter of seconds,

and correlate with simultaneous MS

operation. In order to master these amounts of

data, new analyses techniques are required.

These can consist of data pre-treatment,

adequate plotting of visual results and

statistical techniques to facilitate

interpretation.

Program

The tasks proposed for this thesis include:

Literature research on Ni-Fe catalysts for methane dry reforming

Theoretical background study on (Q)XAS

Data treatment, analysis and interpretation of QXAS spectra.

Combining and interpreting results.

Joining a XAS campaign at a synchrotron might be possible.

Doelstelling:

BIG data are increasingly encountered in research as measurements

become more complex and acquisition times are reduced. In order to

master these amounts of data, new analyses methods are required, allowing

for swift data visualisation, automated data treatment and accessible

interpretation.

Locatie:


Website:


17232: Automatic generation of microkinetic models for

polycyclic aromatic hydrocarbon formation during pyrolysis of

hydrocarbons

Promotor(en): Kevin Van Geem, Joris Thybaut

Begeleider(s): Alexander Vervust

Contactpersoon: Alexander Vervust

Goedgekeurd voor: Master of Science in Chemical Engineering

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Nog onbeslist voor: Master of Science in de ingenieurswetenschappen:

chemische technologie

Aantal studenten: 1

Aantal

masterproeven: 1

Probleemstelling:

Justification

Polycyclic aromatic hydrocarbons (PAHs) are a group of more than 100

chemicals that can be produced from various sources, such as the

incomplete combustion of heating fuels, oil refining processes and the

combustion of diesel fuels. Many PAHs are known to be carcinogenic or

mutagenic and important precursors to soot, which has been linked to

human morbidity and global warming.

A detailed microkinetic model, which is able to describe the chemical

kinetics of PAH formation over a wide range of process conditions and

feedstocks, is an invaluable tool for evaluating the performance of new and

existing technologies in reducing the amount of PAHs. Because such

models may contain up to thousands of reactions and species, constructing

them by hand can be tedious and error-prone. The starting point of network

generation is that a limited number of chemical reaction families can be

used to understand and describe the gas phase reactions occurring on the

molecular scale. This makes it possible to generate all possible reactions

that a given chemical species can undergo in the gas phase. Apart from the

reaction network, accurate values for the thermodynamic and kinetic

parameters are required to allow reactor simulation. If no experimental or

theoretical values for these parameters are available, estimation methods

are used. It is evident that an extensive database of thermodynamic and

kinetic parameters, and values for parameter estimation methods is

indispensable.

Program

Literature survey on thermodynamic and kinetic parameters of

aromatic species and reactions involving aromatic species

respectively for use in automatic network generation.

Extending the Genesys database with group additive values based on

the literature survey and data available from ab initio calculations.

Perform pyrolysis experiments.

Automatic kinetic model generation and validation with

experimental data.

Doelstelling:

The aim of this thesis is to extend the databases of the automatic network

generation software Gensys to be able to generate microkinetic models

which are able to describe the formation of polycyclic aromatic

hydrocarbons during the pyrolysis of hydrocarbons. A microkinetic model

will be generated and validated with experimental data.

Locatie:


Website:


17287: Computational Fluid Dynamic simulation of

heterogeneous catalytic reactors

Promotor(en): Kevin Van Geem

Begeleider(s):

Contactpersoon: Laurien Vandewalle

Goedgekeurd

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Probleemstelling:

Justification

Many innovative, catalytic technologies have been developed in the past

decade as a response to the world’s rapidly growing demand for a more

efficient and sustainable exploitation of energy and material resources.

New catalysts and improved processes are needed to guarantee the

industrial competitiveness of novel technologies.

The understanding and optimizing of heterogeneous catalytic reactors

requires a detailed knowledge of the heterogeneous surface reactions and

the interaction of the active surface with the surrounding reactive flow.

Consequently, the heterogeneous surface reactions must be analysed

together with potential homogeneous gas-phase reactions, mass transport

in the gas-phase, as well as heat transport between the gas-phase and solid

structures. In this respect, Computational Fluid Dynamics (CFD) can offer

a lot more insights than the simplified 1D reactor models that are mostly

used for the description of fixed bed reactors. The CFD simulations can

also be used as a validation tool for more sophisticated 1D and 2D reactor

models that include for example axial and radial backmixing.

Figure 1 - CFD modelling of a fixed bed reactor geometry.

Program

Literature survey on the operator-splitting technique and other

computational tools that can be used couple computational fluid

dynamics with microkinetic modelling in a more efficient way.

Getting acquainted with the opensource CFD package OpenFOAM

and the catalyticFOAM code.

3D CFD simulation of the oxidative coupling of methane in different

fixed bed configurations and comparison with the results obtained

with 1D and 2D reactor models. The 1D and 2D simulations will be

performed in either Chemkin or Cantera.

Doelstelling:

The purpose of this master thesis is to couple CFD simulations with

detailed kinetic modelling in heterogeneous catalysis. This will allow to

evaluate the performance of fixed bed reactors for the oxidative coupling

of methane.

Locatie:


Website:


17191: Computational investigation of penultimate effects in

RAFT polymerization

Promotor(en): Marie-Françoise Reyniers, Maarten Sabbe

Begeleider(s):

Contactpersoon: Maarten Sabbe

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Probleemstelling:

Justification

Controlled Radical Polymerization (CRP) techniques have shown much

potential to produce well-defined polymers with a broad range of

applications; including high performance coatings, adhesives, drug

delivery systems, etc. Among these CRP techniques, RAFT polymerization

has been put forward as a very promising CRP technique, due to its strong

resemblance to free radical polymerization and its high monomer

flexibility, making it a universal polymerization technique, additionally

interesting due to the absence of a toxic catalyst. The principle of RAFT

polymerization is presented in the figure below:

By modeling RAFT polymerization reactions starting from a first

principles approach, fundamental insight is gained in the complex interplay

of the stereoelectronic effects between the reacting molecules. These

effects might extend well beyond the nearest neighbors and have a

detrimental influence on the thermodynamic and kinetic parameters of the

reaction. Correlations between the reactivity and the structural aspects of

different RAFT agents and monomers will not only deepen our

understanding of the reaction mechanism, but also allow us to predict the

outcome of that reaction in terms of e.g., molecular weight, monomer

sequence, stereo regularity… Moreover, this will aid us in rationally

designing optimal reactants, reaction conditions, chain transfer agents

(CTA), etc

Program

Literature survey on RAFT copolymerization with a focus on

mechanistic aspects on currently used combinations of monomers

and RAFT agent.

Computational investigation with state-of-the-art ab initio methods

on the addition-fragmentation reactions for interesting RAFT

copolymerization systems.

Kinetic modeling using the ab initio determined parameters to i)

optimize the conditions in specific RAFT copolymerization reactions

and ii) explore new combinations of monomers with specific RAFT

agents.

Doelstelling:

A computational study will be performed to investigate the influence of

penultimate effects on the addition-fragmentation equilibrium step in

reversible addition-fragmentation chain transfer (RAFT) polymerization,

an indispensable next step in the accurate modelling of the synthesis of

specialty copolymer architectures.

Locatie:


Website:


17329: Continuous flow investigation of industrially relevant aldol

condensations

Promotor(en): Joris Thybaut, Pascal Van Der Voort

Begeleider(s): Jeroen Lauwaert, Anton De Vylder

Contactpersoon: Anton De Vylder

Goedgekeurd

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Probleemstelling:

Justification

The aldol condensation is an important reaction to create new C-C bonds

and yield larger and more complex molecules. It is widely used in the

pharmaceutical industry as well as for the preparation of fine chemicals,

perfumes and synthetic flavors. Furthermore, aldol condensation provides

perspectives for the transition from a fossil to renewable resources, e.g., in

the valorization of glycerol, which is a byproduct in the production of

biodiesel, or the conversion of furan compounds such as 2-furaldehyde

(furfural) and 5-(hydroxymethyl)furfural (HMF), which are obtained by

dehydration of sugars, into hydrocarbon fuels.

Aldol condensations are, currently, industrially performed in batch

reactors. Making the switch from batch to continuous processes may be

difficult, costly and time consuming. This switch is, currently, only

beneficial if the corresponding production capacity exceeds 10 000 tonnes

per year. However, thorough research on flow chemistry will decrease this

threshold at least by a factor of 10. Continuous operation has also

advantages at the laboratory scale, i.e., the use of a continuous reactor set-

up facilitates the investigation of catalyst deactivation which will lead to

the development of reusable catalyst and, hence, provides economic and

environmental benefits.

In most cases, a homogenous, base catalyst such as NaOH or Na2CO3 is

used to catalyze aldol condensations. However, in a search for more

sustainable chemical processes, heterogeneous alternatives for the

homogenous catalyst are being pursued. The development of new

heterogeneous catalysts is typically a trial and error process. It is the

ambition of the research group ‘Catalytic Reaction Engineering’ within the

Laboratory for Chemical Technology to further enhance the discovery rate

by means of a more rational design of catalytic materials. (Micro)kinetic

modelling of the catalytic chemistry will provide us with a unique insight

into the effect of the catalyst properties on the behavior via the so-called

catalyst descriptors. This insight can be exploited in the design and

optimization of new and innovative catalysts.

Program

Different periodic mesoporous organosilica materials, functionalized with

a methyl substituted secondary amine, will be synthesized in collaboration

with the Center for Ordered Materials, Organometallics and Catalysis

(COMOC; S3). The catalysts will be used in aldol condensation

experiments of several types of aldol condensations, i.e., the self-

condensation of butanal, and the cross-condensations of benzaldehyde with

acetophenon and furfural with acetone to obtain kinetic data sets. This will

be performed in both a batch type reactor, as well as a continuous flow

reactor. Special attention will be paid to the influence of water and the

relation with the surface hydrophobicity on the catalyst’s stability with

time-on-stream. Afterwards, the experimental results from both reactors

will serve as a basis for the microkinetic modelling. Data obtained on

different catalysts will be treated simultaneously by distinguishing between

kinetic and catalyst descriptors in the model. Having constructed an

adequate kinetic model, optimal catalyst descriptor values will be

determined. These values will constitute the feedback from the

microkinetic modelling towards the catalysts synthesis to actually

synthesize the corresponding catalyst.

Doelstelling:

Synthesis of acid-base cooperative heterogeneous catalysts and assessing

the kinetic performance in the self-condensation of butanal, the cross-

condensation of benzaldehyde with acetophenon and furfural with acetone.

Acquisition of a fundamental understanding of the reaction mechanism,

potential deactivation effects, and catalyst property effects on the reaction

rate of the different types of aldol condensations via microkinetic

modelling aiming at a rational design of a novel generation of

heterogeneous aldol condensation catalysts.

Locatie:


Website:


16709: Design of a Carbon Neutral Process for the Synthesis of

Methanol


Begeleider(s):

Contactpersoon: Kasun Govini Thanthrige

Goedgekeurd

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Aantal studenten: 1

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Probleemstelling:

Justification

Carbon-based fuels and materials form the basis of our high standard of

living. A drastic change away from a carbon-based society is not expected.

However, to avoid the dangerous build-up of CO2 in the atmosphere and

the associated climate change, a transition from a society based on cheap

and abundant fossil reserves to a society based on CO2-neutral activity is

required. Using clean energy sources to produce fuels is a way to reduce

CO2 emissions, hence helping the environment while creating new

opportunities for the chemical industry.

To realize this goal, multiple steps are required, i.e., direct CO2 capture

from air, electrochemical water splitting using photovoltaic electricity, and

CO2 hydrogenation to methanol. Methanol is a unique platform molecule

which can serve as fuel and building block of the chemical industry. Each

of these individual steps in the process has reached a certain level of

maturity, but the combination and integration of these processes has not yet

been studied.

In this project, a process is designed for the production of methanol,

integrating CO2 capture, hydrogen production, and CO2 hydrogenation to

determine optimal working regime and integration. Our goal is to then

perform a techno-economic analysis, establish the feasibility of this

process, and understand the bottlenecks to implement this technology. In

addition, alternative schemes will be considered, e.g., direct CO2

electroreduction, and integration with biomass.

Program

Literature survey on the state-of-the-art for the individual steps: CO2

hydrogenation, direct CO2 capture and the production of solar

hydrogen.

Design an integrated process for the production of methanol using

state-of-the-art technology, as well as future expected state-of-

technology .

Perform a techno-economic evaluation of the overall process to

identify technolgy bottlenecks.

Evaluate alternative technologies.

Doelstelling:

To design and assess the techno-economic impact of a carbon-neutral

process for the production of fuels integrating CO2 capture from air,

electrochemical hydrogen production and catalytic hydrogenation of CO2.

Locatie:


Website:


17168: Design of Pt-based bimetallic catalyst particles for the

catalytic dehydrogenation of propane


Begeleider(s):

Contactpersoon: Stephanie Saerens

Goedgekeurd

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Probleemstelling:

Justification

Propylene plays a key role in petrochemical industry for its use in

polypropylene production. The conventional source for light alkenes is

steam cracking, but this high-temperature process (>1000 K) is not

selective and cannot satisfy the growing demand. For this reason,

alternative pathways such as on-purpose catalytic propane dehydrogenation

have been investigated. However, the catalyst performance for this reaction

still needs improvement.

A promising Ga-promoted Pt bimetallic catalyst has been developed for

alkane dehydrogenation reactions at the Laboratory for Chemical

Technology (LCT). Currently, researchers are unaware of the shape of the

bimetallic metal particle, the exact composition of the active alloy surface

and the influence of support on the active phase.

Recent studies have elucidated the propane dehydrogenation reaction

mechanism. However, the influence of the bimetallic catalyst shape and

support has never been studied explicitly, and these issues need to be

addressed as well. Innovative developing methods, e.g. the semi-empirical

embedded-atom method (EAM), can provide insight in the catalyst shape

and segregation state of the metal particle. A combination of density

functional theory (DFT) methods and semi-empirical methods are

necessary to model the metal-on-support catalyst particles. These

innovative approaches will lead to useful insight into the characteristics of

the bimetallic catalyst particle.

Program

1. Determine the optimal shape and composition of various Pt-Ga

alloys and model the interaction between particle and support using

DFT calculations on subnanometer particles on support.

2. Using the resulting catalyst models, determine computationally the

influence of the bimetallic catalyst (metal-on-support) on the

dehydrogenation of propane, focusing on the key steps that

determine the activity and selectivity in the dehydrogenation

reaction.

3. Investigate the effect of different promoter elements on the surface of

the catalyst particle and the chosen representative reaction steps.

4. Interpret the generated data to provide feedback to the experimental

work in terms of catalyst composition, catalyst shape, and reaction

mechanism.

5. Construct a kinetic model to simulate the performed experiments

which allows to provide feedback on the experimental conditions

and/or catalysts to be investigated.

Doelstelling:

The characteristics of bimetallic particles-on-support, which are typically

used for the propane dehydrogenation reaction, will be unraveled using

quantum chemical calculations. In particular, the focus is on catalyst shape,

composition and interaction with the support.

Locatie:

Website:


17804: Designing a novel core-shell structured bifunctional

material for CO2 utilization

Promotor(en): Vladimir Galvita

Begeleider(s):

Contactpersoon: Jiawei Hu

Goedgekeurd

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Aantal studenten: 1

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Probleemstelling:

Justification

Carbon dioxide, a major green-house gas, has become an attractive source

of carbon for the chemical industry owing to its low cost and high

availability. Valorizing CO2 towards useful chemicals is particularly

interesting from both environmental and economic point of view. Cyclic

conversion through Catalyst-assisted Chemical looping Dry Reforming

(CCDR) over a bifunctional bed composed of a physical mixture of a Ni-

based reforming catalyst and a Fe-based oxygen storage material (OSM) is

a novel technology for CO2 utilization. In this process, a given reaction is

divided into two half-cycles: (1) CH4 and CO2 are first converted over Ni

into H2 and CO which reduce Fe3O4 to metallic Fe; (2) reduced Fe3O4 is

regenerated via interaction with CO2 resulting in CO production.

Compared to the conventional dry reforming of CH4, which produces

syngas, CCDR is designed for maximized CO2 conversion (three molecule

of CO2 per molecule of CH4). Here, A core-shell structured

Fe2O3@ZrO2(core)@Ni-RhCe(shell) bifunctional nanomaterial is

proposed, aiming to integrate the two half-cycles into one unit. The

bifunctional nanomaterial will possess a small core-thick shell structure.

The small core, Fe2O3@ZrO2 (composed of a Fe2O3 nanocore and a thin

and porous ZrO2 shell), acts as the OSM. The thick shell, Ni-RhCe (a

mesoporous NiO layer embedded a trace amount of Rh and CeO2), acts as

the reforming catalyst, where Rh helps hydrogen spillover to increase the

reducibility of Ni and CeO2 (as an oxygen reservoir) enables the oxidation

of deposited carbon and thus maintaining stable catalytic activity.

Program

Literature survey on catalyst-assisted chemical looping reforming, as

well as on the synthesis methods of core-shell structured materials.

< >stablish the synthesis route of Fe2O3@ZrO2(core)@Ni-

RhCe(shell) nanomaterials, synthesize a series of materials with

different thickness of shell and molar ratio of Ni to Fe2O3.

Activity and stability performance tests of the materials for CCDR

will be performed in a step response reactor.

Characterization of the fresh and spent samples by N2 sorption,

ex/in-situ XRD, TPR, TPO and STEM-EDX,…

Analysis the relationship between the activity/stability and the

materials’ structure (including the thickness of shell and the relative

ratio of Ni catalyst to Fe2O3 OSM).

Doelstelling:

The aim of this thesis is to synthesize, characterize and assess the

bifunctional Fe2O3@ZrO2(core)@Ni-RhCe(shell) nanomaterial for its

application in catalyst-assisted chemical looping dry reforming.

Locatie:


Website:


17806: Development of a bifunctional material for CO

production from CO2 by catalyst-assisted combined chemical

looping


Begeleider(s):

Contactpersoon: Lukas Buelens

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Aantal studenten: 1

Aantal

masterproeven: 1

Probleemstelling:

Justification

Today, global research interest with respect to mitigating CO2 emissions

is shifting from a short-term strategy of CO2 capture and storage towards a

long-term closed-loop approach, CO2 capture and utilization. Generation

of syngas from CO2 and H2O and its subsequent conversion into

chemicals or clean fuels can be particularly interesting when using

processes driven by renewable energy. Besides providing a method for

CO2 valorisation, such an approach allows to store renewable energy in

times of abundance. The stored energy can be released in times of

shortage.

Here, the objective is to convert CO2 and CH4 into CO by means of

catalyst-assisted combined chemical looping. This method combines a

catalyst for CH4 reforming with an iron oxide and calcium oxide material.

A mixture of CH4 and excess CO2 are reformed over a catalyst (e.g. Ni) to

form syngas. This syngas reduces the iron oxide material upon its

oxidation to CO2 and H2O. The produced CO2 is fixated as CaCO3 and,

hence, the effluent solely consists of H2O. The materials are regenerated

by decomposition of CaCO3 to CaO and CO2, which reoxidizes iron oxide

while producing CO. This decomposition can be realized either

isothermally by means of a sweep gas, or by elevating temperature.

Compared with conventional dry reforming of CH4, this process allows an

intensified production of CO from CH4 and CO2:

Conventional dry-reforming:

Catalyst-assisted combined chemical looping:

The high operating temperature (700-800°C) along with structural changes

of the solid materials are known to cause deactivation due to sintering or

formation of inert solid phases. Particle growth due to sintering results in a

decrease of the specific surface area. By means of a mesoporous metal

oxide shell (e.g. ZrO2, SiO2, …), a physical barrier between particles can

be formed which will tremendously improve thermal stability while

allowing mass transport through the pores.

Program

Literature survey: (i) CO2 capture and conversion, (ii) synthesis of

mesoporous metal oxides and core-shell structured materials, and

(iii) kinetic modelling of solid-gas reactions

Synthesis of a bifunctional material: CaO(core)-

MOx(shell)+Fe2O3(impregnated)

Characterization of the prepared materials by SEM, STEM-EDX,

TPR, (in situ) XRD, …

Activity and stability performance tests of the materials for catalyst-

assisted chemical looping

Kinetic modelling of the separate processes

Doelstelling:

The purpose of this thesis subject is to synthesize, characterize and test a

bifunctional material for conversion of CH4 and CO2 into CO by

catalyst-assisted combined chemical looping.

Locatie:


Website:


17269: Experimental Heat Transfer Studies in a Hot Flow

Vortex Reactor

Promotor(en): Geraldine Heynderickx, Kevin Van Geem

Begeleider(s):

Contactpersoon: Shekhar Kulkarni


Niet behouden

voor:



Aantal studenten: 1

Aantal

masterproeven: 1

Probleemstelling:

Justification

Gas Solid Vortex Reactors (GSVR) are becoming popular for applications

demanding high interphase heat transfer like biomass fast pyrolysis.

GSVRs exhibit densely packed, rotating fluidized beds due to a centrifugal

force generated by tangential gas injection in the cylindrical unit. Amongst

other benefits, gas-solid slip velocities are higher as compared to

conventional fluidized beds, resulting in improved heat and mass transfer

between the phases. It is expected that achieving convective heat transfer

coefficients of ~500-800 W/(m2K) in vortex reactors are within reach.

Our experience has learnt that drag force correlations in the gravitational

field cannot be extended to Gas Solid Vortex Units. Recently, it has been

developed in LCT a new drag correlation for modeling momentum transfer

on GSVR based on experimental data; and it is expected that a heat transfer

correlation applicable in vortex technology will have to be developed as

well.

In order to confirm the expected increase in heat transfer as compared to

the gravitational fluidized beds, heat transfer experiments in an

experimental GSVR setup (see photo) will be carried out. The experiments

will be performed under a wide range of operating conditions (gas

temperatures, gas flow rates, solids material and size, and solids flow rate).

The unit is currently equipped for Particle Image Velocimetry (PIV) to

study the fluidized bed properties (like solid velocities, volume fractions,

etc.). It will also be equipped with an Infrared (IR) camera to monitor the

bed temperatures.

Program

1. Literature study on heat transfer studies in GSVRs.

2. Explorative theoretical calculations for heat transfer coefficient for

vortex reactor, and design of experiments thereof.

3. Heat transfer experiments for various solids like HDPE, Aluminium,

Alumina, etc. Develop a correlation for calculating heat transfer

coefficient from these experiments.

4. Studying heat transfer in solid entrainment mode and in dedicated

solid outlet mode.

Doelstelling:

To perform experimental heat transfer studies in the Hot Flow Vortex

Reactor setup and develop a heat transfer correlation thereof.

Locatie:


Website:


17277: Experimental investigation of particle segregation in a

Gas Solid Vortex Unit (GSVU)

Promotor(en): Geraldine Heynderickx

Begeleider(s):

Contactpersoon: Maria del Mar Torregrosa Galindo


Niet behouden

voor:



Aantal studenten: 1

Aantal

masterproeven: 1

Probleemstelling:

Justification

The Gas Solid Vortex Reactor is a novel chemical reactor technology,

where a bed of solid particles is set into rotating motion in the cylindrical

chamber of the reactor by tangentially injected gas. A cold-flow set-up is

available at the LCT and studies on the gas-solid flow patterns developed

in the GSVR are in progress. A Particle Image Velocimetry technique

(PIV) is used for solids velocity measurements in the GSVR. The solids

velocities are calculated by recording and subsequently cross-correlating

successive images of the bed recorded in short, known time intervals.

The capabilities of the GSVR in terms of particle segregation are still to be

evaluated. The idea is to introduce loads of particles with different sizes

and/or density ratios, and to evaluate through Digital Image Analysis

(DIA) the effectivity of the segregation. For proper analysis of the images,

a new code will be developed (using Matlab) for the DIA of the images.

PIV processing software will be used to determine velocity distributions.

Program

Literature review related to particle segregation characterization.

Preparation of mixes of solids of different size and density ratios.

Acquisition of series of PIV images for various solids mixtures

inside the GSVR.

Development of an image processing code for analyzing the images

and stablishing the effectivity of the segregation.

Presentation of the results in summarizing tables and graphical

illustrations, preparation of the thesis, and of the final presentation.

Doelstelling:

The goal of this project is to investigate experimentally different aspects of

particle segregation within the rotating bed of a GSVU. Different loads of

polymer particles of diverse size and density will be introduced in the

GSVU, and images of the particles will be acquired, processed and

analyzed. Aspects such as stratification and velocity distribution within the

solids bed are to be evaluated.

Locatie:


Website:


17251: Fast Pyrolysis of Pinewood in the Gas-Solid Vortex

Reactor


Begeleider(s):

Contactpersoon: Arturo González Quiroga


Niet behouden

voor:



Aantal studenten: 1

Aantal

masterproeven: 1

Probleemstelling:

Justification

Fast pyrolysis is a promising technology for obtaining chemicals and fuels

from renewable biomass. Fast pyrolysis is boosted by high interfacial heat

transfer coefficients, rapid removal of the pyrolysis vapors and precise

temperature control. Several fast pyrolysis reactor technologies has been

developed during the last decades, with the ones scaled up to

demonstration plants being spouted bed, static and circulating fluidized

bed, rotating cone, ablative and auger reactor. These reactor technologies

exhibit limited interfacial heat transfer coefficients and hot spots inside the

reactor. These issues can be overcome with the Gas-Solid Vortex Reactor

(GSVR) where a dense bed of particles is generated in a centrifugal field,

allowing for significantly larger gas-solid slip velocities. In the GSVR unit

shown in Figure 1 gas is injected at high velocity via tangentially oriented

inlet slots in a cylindrical chamber in which biomass pellets are

continuously fed. Momentum transfers from the gas to the pellets, causing

the latter to rotate, thus generating a large radially outward centrifugal

force which opposes the radially inward gas-solid drag force.

A GSVR demonstration unit has been designed, constructed and tested at

cold flow conditions at the Laboratory for Chemical Technology (LCT). A

broad range of operation conditions in the 80 mm diameter and 15 mm

height GSVR can be evaluated: N2 mass flow rates of 5-10 g s-1 and

biomass feed mass flow rates of 0.14-1.4 g s-1. Particulate flow

experiments revealed that the designed GSVR achieves a sufficiently high

centrifugal-to-drag force ratio sustaining a rotating fluidized bed within a

broad range of operation conditions and shows great potential for biomass

fast pyrolysis and related processes.

Program

Survey literature on fast pyrolysis technologies focusing on the

relationships between feedstock composition, operation conditions

and bio-oil molecular composition.

Prepare and characterize pinewood for fast pyrolysis experiments.

Preparation includes grinding, drying and sieving. Characterization

comprises aspect ratio, particle size distribution, moisture, ashes and

elemental composition.

Perform continuous fast pyrolysis experiments in the GSVR

demonstration unit with a biomass mass flow rate of 0.3 g s-1 and

gas outlet temperatures from 723 to 823 K.

Characterize the obtained bio-oil by means of elemental and

comprehensive two-dimensional gas chromatography analysis, and

typical bio-oil tests. The latter includes water content, ashes, total

acid number.

Doelstelling:

The aim of this thesis is to produce bio-oil from pinewood in the Gas-Solid

Vortex Reactor demonstration unit and carry out its elemental and

compositional characterization.

Locatie:


Website:


17230: Genesys: automatic generation of kinetic models


Begeleider(s):

Contactpersoon: Ruben Van de Vijver

Goedgekeurd

voor:



technologie

Niet behouden

voor:

Nog onbeslist

voor:

Aantal studenten: 1

Aantal

masterproeven: 1

Probleemstelling:

Justification

Accurate chemical kinetic models are extremely powerful and valuable.

Many significant public policy and business decisions are and have been

made on the basis of predictions using detailed kinetic models. However,

for most technologically important systems constructing a reliable and

sizable kinetic model remains to be very difficult and time consuming.

Recent advancements in chemistry and informatics have enabled a new

kinetic modelling approach of tracking each molecule and intermediate

throughout the reaction process using fundamental kinetics information.

Several tools have been developed to automatically build large kinetic

models. Such models contain typically thousands of reactions involving

hundreds of intermediates with only a small fraction of the reaction rate

coefficients known experimentally. Moreover, it is usually impossible to

measure the concentrations of all the kinetically significant chemical

species. Therefore, estimation methods are necessary to assign rate

coefficients to reactions and thermodynamic properties to species. These

estimation methods rely on highly accurate data for a limited set of

molecules and reactions. The calculation of this accurate data has been

automated in Genesys, a recently developed kinetic model generator

program

The increasing global energy demand and the limited reserves of fossil

fuels, alongside the environmental issues accompanying combustion of the

latter, have led to an important shift to renewable resources. These

resources, mainly originating from biomass, entail a wide variety of hetero-

atomic species, which have a different chemical behaviour compared to

hydrocarbon molecules. This behaviour is yet to be understood, and many

research projects focus on the developing of kinetic models for the

pyrolysis and combustion of biomass derived fuels. The lack of data and

the poor predictions of many estimation methods are one of the main

bottlenecks in unravelling the underlying chemistry. High level ab initio

calculations are important in addressing the current data gap and can be

used to improve the accuracy of common estimation methods such as

group additivity.

Program

Determining of group additive values from ab initio calculations

using Genesys for reaction families where data is lacking.

Building kinetic models for the pyrolysis of biomass derived species

and validating them to experimental data.

Assessing the importance of the newly calculated data and analyzing

the kinetic models via sensitivity analyses and rate of production

calculations.

Doelstelling:

The aim of this master thesis is to develop ab initio kinetic models for the

pyrolysis of molecules derived from biomass via newly calculated group

additive values.

Locatie:


Website:

17226: Investigation of biomass fast pyrolysis via pyrolytic

degradation of model compounds


Begeleider(s):

Contactpersoon: Sri Bala Gorugantu


Niet behouden

voor:



Aantal studenten: 1

Aantal

masterproeven: 1

Probleemstelling:

Justification

In the past decade, lignocellulosic biomass has been intensively studied as

a resource for alternative fuels and chemicals. One promising avenue is the

thermochemical route, in which lignocellulosic biomass is subjected to fast

pyrolysis, a process which results in large quantities of bio-oil next to

smaller amounts of gaseous products and char. Lignocellulosic biomass

consists of cellulose (30-50 wt.%), hemicellulose (15-30 wt.%), lignin (10-

30 wt.%), and ash (5-10 wt.%) on a dry basis. Lignin, a heterogeneous

polymer made up of phenolic molecules like syringol (S), guaiacyl (G) and

p-hydroxyphenyl (P) units linked by several types of bonds, is of special

interest because (a) it is not yet fully utilized in current bio-refining

concepts, and (b) due to its composition it has the potential as source for

interesting high-value chemicals such as vanillin, resins and adhesives.

To design and optimize a suitable process for the production of high-

quality bio-oil or fine chemicals, it is important to understand the detailed

chemistry of biomass fast pyrolysis. Given its complexity and

inhomogeneity, experimental and theoretical studies are generally

performed with model compounds, that resemble some features of real

biomass.

Program

Literature study on lignin model compounds such as dimers and

trimers, experimental and modelling approaches for fast pyrolysis of

lignin.

Experimental study of the pyrolysis of lignin model compounds

using the tandem micropyrolyser setup.

Apply and extend kinetic models available in the literature to

simulate the experimental data.

Doelstelling:

Develop a detailed understanding of lignin pyrolysis chemistry by

investigating the thermal decomposition of lignin model compounds

through experimentation and kinetic modeling.

Locatie:


Website:


17285: Kinetic Analysis of Pharmaceutical Reactions: Synthesis

of Diphenhydramine

Promotor(en): Kevin Van Geem, Chris Stevens

Begeleider(s):

Contactpersoon: Pieter Plehiers


Niet behouden

voor:



Aantal studenten: 1

Aantal

masterproeven: 1

Probleemstelling:

Justification

Diphenhydramine is an anti-histamine that is used for the treatment of

allergies, but also as sedative and pain-killer. As is the case for most

pharmaceutically active molecules, a “good” synthesis is known. However,

none of these known syntheses can guarantee that they are optimal. Work

is being done on software to determine an “optimal” synthesis, based on

automated retro-synthetic analysis. [1] Solely searching for potential

synthetic pathways is not a major challenge: the reaction network

generation tool Genesys is (with some minor changes) already capable of

doing so. However, with increasing complexity of the synthesis, the

number of possible pathways increases exponentially. Hence, the number

of investigated pathways must be drastically reduced. This can be done by

continuously scoring the syntheses and only continuing with the most

promising ones. This score depends on many things such as reactant

availability, separation, … One very important factor is the kinetics of the

constituting reactions. Obviously, faster reactions will be preferred above

slower ones.

The problem with pharmaceutical reactions is that very little is

known/published on the kinetics, especially as detailed as desired. Best-

case scenarios for pharmaceutical kinetics is the publication of yields and

conversions. These can give some idea of the kinetics, but provide very

little room for extrapolation and predictive use. With the development of

on-the-fly generation of kinetic data in Genesys, it is possible to efficiently

calculate kinetic data for several molecules at once, accelerating the

generation of kinetic data. Once kinetic data is available for several

different types of molecules, a regression of these data can be performed in

order to determine GAV’s for several new groups.

Program

Literature survey on existing kinetic/experimental data relevant to

the synthesis of diphenhydramine

Ab-initio calculation of the properties of reactants, intermediates and

products appearing in the synthesis of diphenhydramine, taking into

account the specific conditions of the reactions: liquid phase and

(homogeneously) catalyzed.

Determination of kinetic parameters for the reactions in the (known)

synthetic pathways for diphenhydramine

Regression of group additive values for the specific groups occurring

in the species that are involved in the reaction of the syntheses.

1. Szymkuć, S.; et al.., Angewandte Chemie International Edition

2016, 55, (20), 5904-5937.

Doelstelling:

The aim of this master thesis is to study the kin etics of the reactions that

are relevant or related to the synthesis of Diphenhydramine. The study will

be based on ab-initio calculations. The initial goal is to obtain kinetic data

for these reactions. Ideally, this data will be used to obtain group-additive

values (GAV’s) so kinetics for a wider range of related reactions can be

predicted.

Locatie:


Website:


17201: Kinetic modeling of the pyrolysis of lignin model

compounds


Begeleider(s):

Contactpersoon: Hans-Heinrich Carstensen

Goedgekeurd

voor:



technologie

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voor:

Nog onbeslist

voor:

Aantal studenten: 1

Aantal

masterproeven: 1

Probleemstelling:

Justification

Furan derivatives including dimethyl furan are easily obtainable through

catalytic conversion of the cellulosic fraction of biomass. For this reason,

dimethyl furan has been studied intensively in the past few years. Among

these studies was a flow reactor experiment performed at LCT, which was

published in 2013. Since then, subsequent modelling studies casted doubts

about the reliability of this data set. Consequently the experiments were

repeated with the same but slightly modified bench-scale setup and indeed,

the original data could not be reproduced. However, the product yields

found with both sets of experiments are quite comparable and confirm (a)

the formation of substantial amounts of phenol, not seen in any other

experiment, and (b) the tendency to produce cyclopentadiene and

molecular weight growth species. The new experimental data set, which

seems to be in good agreement with expectations, has not been published

yet.

Although several kinetic models for DMF exist, some contain estimated

rate expressions while others seem to use irreversible reactions in order to

reproduce experimental data. The relevant potential energy surfaces are

incomplete or not developed at all. Despite the number of papers published

on DMF chemistry, there is still a lot of room for improvement.

Program

Literature research on experimental and theoretical furan, methyl

furan (MF), and DMF pyrolysis and oxidation studies.

Familiarization with electronic structure calculations using Gaussian

software, and conversion of this data to thermodynamic and kinetic

properties.

Analyze the performance of existing kinetic models for DMF and

identify important reaction pathways.

Explore options to use automated mechanism generation programs

such as RMG or Genesys to generate kinetic mechanisms for DMF

pyrolysis

Perform ab initio calculations on potential energy surfaces needed to

develop an improved DMF mechanism.

Validate the new model against all available data. Identify the

important DMF converting reactions and the chemistry leading to

oxygen-free aromatic species.

Doelstelling:

Development of a first-principle elementary step kinetic mechanism for

dimethylfuran pyrolysis and validation against in-house and literature

experimental data.

Locatie:


Website:


17176: Kinetics Simulation in Emission Control: Catalytic

Oxidation of Tricholoroethene Plasma Degradation Products

Promotor(en): Joris Thybaut, Rino Morent

Begeleider(s): Jolien De Waele, Sharmin Sultana

Contactpersoon: Jolien De Waele

Goedgekeurd

voor:



technologie

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voor:

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voor:

Aantal studenten: 1

Aantal

masterproeven: 1

Probleemstelling:

Justification

Mathematical modelling of chemical and physical phenomena is an

important tool in the elucidation of underlying mechanisms and can, if

done properly, provide adequate guidelines for material design and process

optimization. The prior knowledge of the modeler on the investigated

reaction is often (too) determining for the success of simulation efforts. It

is, hence, mandatory, to devise a strategy with respect to available

techniques and theories which will assist rather than confuse novices in the

field.

In order to maximize the information gained from modelling efforts in the

most effective manner, a methodological approach will be developed. The

Laboratory of Chemical Technology (LCT) is expert in the modeling of the

intrinsic kinetics of large-scale chemical reactions and will team up with

the Plasma Technology group from the Applied Physics department to

demonstrate the versatility of the proposed methodology for the further

catalytic oxidation of tricholoroethene and its degradation products after a

plasma treatment.

Emissions of volatile organic compounds (VOCs) significantly contribute

to air pollution and need to be abated adequately. Plasma techniques

followed by conventional catalysis offer some strategic advantages in this

respect, i.e., a plasma pretreatment of the VOCs to be abated allows

reducing the required temperature in the post catalytic treatment.

Program

Assessment of the reactor configuration and operating conditions for the

acquisition of intrinsic reaction kinetics. Measurement of an intrinsic

kinetics data set in which operating conditions such as the temperature,

inlet partial pressures and space time will be systematically varied. A

qualitative analysis of the data set will provide guidelines for kinetic model

construction and subsequent model regression. The latter will result in an

enhanced insight in the oxidation reaction mechanism as well as in

concrete guidelines for the selection of the most adequate catalyst.

Technologiepark and Technicum

Doelstelling:

Development and implementation of a modeling methodology for catalyst

selection and design. Demonstration and validation of this methodology for

the oxidation of trichloroethene and its degradation products after plasma

treatment.

Locatie:


Website:


17233: Large eddy simulation of turbulent reacting flows


Begeleider(s):

Contactpersoon: Pieter Reyniers


Niet behouden

voor:



Aantal studenten: 1

Aantal

masterproeven: 1

Probleemstelling:

Justification

Steam cracking is the predominant process for the production of some

important bulk chemicals including ethene, propene and 1,3-butadiene.

Over the last several decades, extensive research has been carried out

which has led to a thorough understanding of the reaction chemistry of the

steam cracking process. Elaborate networks which describe the radical gas

phase chemistry have been used in complex 1D or 2D reactor simulations

(COILSIM1D) and in 3D computational fluid dynamics simulations using

Reynolds Averaged Navier-Stokes (RANS) turbulence models. However,

these simulations do not allow to fully grasp the effect on heat transfer

rates and the temperature distribution in so-called enhanced coil geometries

or other advanced geometries.

With High Performance Computing facilities on the Tier2, Tier1 or even

Tier0 level becoming increasingly accessible, the complexity of the models

in computational fluid dynamics has risen accordingly. In contrast to

RANS models in which all turbulent scales are modelled, large eddy

simulations allow to partially resolve the turbulent scales, thus providing a

powerful tool to gain insight in the subtle interactions between turbulence

and chemical kinetics.

This insight in the fluid flow dynamics is crucial for a good understanding

of enhanced reactors. Additionally, the interaction of turbulence and

chemical reactions on the smaller scales strongly determines the yields in

steam cracking. Also simulations of combustion applications are very

sensitive to the turbulence resolution, influencing important parameters

such as flame height and heat release profile.

Program

Literature study on the theory and models used in large eddy

simulations of combustion applications, with the focus on industrial-

scale applications.

Perform periodic large eddy simulations of steam cracking in a

straight tube section using the software package AVBP (CERFACS)

and compare the results with LES results from OpenFOAM and

experimental results obtained at the Von Karman Institute.

Perform large eddy simulations of well-known reference flames and

of an industrially relevant process burners as a first step towards

modeling the complete fireside of steam cracking furnace.

Doelstelling:

The research goal is to investigate turbulent reacting flows via large eddy

simulations with particular attention for the interaction between turbulence

and detailed chemical kinetics.

Locatie:


Website:


17219: Mass transfer in a vortex reactor: experimental and

theoretical study


Begeleider(s):

Contactpersoon: Patrice Perreault

Goedgekeurd

voor:



technologie

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voor:

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voor:

Aantal studenten: 1

Aantal

masterproeven: 1

Probleemstelling:

Justification

Conventional fluidized beds are widely used in the chemical process

industry. Among other advantages, fluidization enhances heat and mass

transfer between gas and particles. However, bypassing of valuable

reactants occur via the bubbles. One possible solution is to take advantage

of the increased acceleration in rotating fluidized beds (high-G field),

thereby increasing the onset of the bubbling regime. In the GSVR-

SG developed at the LCT, the gas is injected tangentially via multiple gas

inlet slots at the outer cylindrical wall. The gas serves both to impart a

rotational motion to the solids and as the fluidization gas. The gas moves

radially and exits via a chimney located at the center of the reactor. The

GSVR-SG also allows to work with dense thin beds without gas

channeling, at higher superficial gas velocities.

Up to now, the experimental studies with the GSVR-SG have mainly

focused on the hydrodynamic aspect in cold flow setups (e.g. effect of the

particle diameter and density, as well as gas injection velocity on the solid

particles velocity profile, bed stability, and solid particles losses; radial

pressure profiles). To fill the gap between the existing knowledge and that

required to ease the deployment of the GSVR technology, we propose to

extend the hydrodynamic characterization studies performed to

characterize the mass transfer.

Program

Literature survey on mass transfer coefficient correlations, as well as

potential physical phenomenon that can be used for experimental

quantification;

Prepare and conduct an experimental plan to investigate the effect of

design and operational variables on reactor-scale mass transfer

coefficients;

Experimentally determine the average mass transfer coefficients over

a wide range of experimental conditions;

Establish correlations for mass transfer coefficients in terms of the

conventional dimensionless groups, and compare the results with the

correlations that apply to gravitational fields (e.g. using the Chilton-

Colburn J-factor analogy (the "jD factors" for mass transfer).

Doelstelling:

The aim of this thesis is to quantify the mass transport coefficient in a

reactive gas-solid vortex reactor (GSVR) via a combined experimental and

theoretical study.

Locatie:


Website:


17063: Mechanistic study of ethanol oxidation on gold silver

catalysts

Promotor(en): Joris Thybaut, Mark Saeys

Begeleider(s): Jenoff De Vrieze

Contactpersoon: Jenoff De Vrieze

Goedgekeurd

voor:



technologie

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voor:

Aantal studenten: 1

Aantal

masterproeven: 1

Probleemstelling:

Justification

Selective oxidation of alcohols to aldehydes and carboxylic acids over

gold-based catalysts using molecular oxygen provides a sustainable

pathway for the production of carbonylic and carboxylic compounds that

otherwise use expensive oxidants and/or harmful organic solvents.

Selective oxidation of ethanol to acetaldehyde, while limiting the

formation of methane, CO2 and ethylene, is particularly interesting

because bio-ethanol is increasingly available and acetaldehyde is one of the

key intermediates in chemical industry. To improve the selectivity and

activity of gold-based catalysts, different promoter elements were

investigated. From these experimental studies, it was found that gold-silver

catalysts are the most promising. The mechanism of ethanol oxidation on

gold catalysts and the role of water and oxygen are already well established

as shown in Figure 1. However, the role of silver and other promotors

remains poorly understood, hampering the optimization of gold-based

oxidation catalysts with high activity and selectivity. To guide the design

of an optimal ethanol oxidation catalyst, a detailed insight in the effect of

the silver promotors on the selectivity and activity is required.

Computational catalysis will be applied in combination with experimental

and characterization data from TU Wien and ETH Zurich to elucidate the

role of promoters and to study the effect of the promotor content on the

catalyst performance.

Program

The following activities will be performed during the project:

A literature review on ethanol oxidation and the gold-based catalysts

for selective alcohol oxidation reactions.

Elucidation of the role of silver as a promoter in gold oxidation

catalysts by applying density functional theory and microkinetic

modelling for a model AuAg(111) surface.

Investigation of the effect of silver content on the selectivity of the

ethanol oxidation process.

1. B. N. Zope, D. D. Hibbitts, et al., Science, 2010, 330, 74-78.

Doelstelling:

Investigation of the role of silver promoters in gold catalyzed alcohol

oxidation reactions. Investigation of the effect of silver on the kinetics of

the most relevant elementary steps and determination of the effect of the

silver content on the acetaldehyde selectivity in ethanol oxidation.

Locatie:


Website:


16707: Mechanistic study of Fischer-Tropsch synthesis


Begeleider(s):


Goedgekeurd

voor:



technologie

Niet behouden

voor:

Nog onbeslist

voor:

Aantal studenten: 1

Aantal

masterproeven: 1

Probleemstelling:

Justification

FTS of clean fuels is rapidly gaining attention as the process to convert a

wide range of hydrocarbon reserves to clean fuels. It is currently being

implemented on an immense industrial scale. The process starts from

synthesis gas, a mixture of CO and H2, and produces products ranging

from methane to light olefins, long-chain hydrocarbons and oxygenates,

depending on the reaction conditions and the catalyst material. Since

synthesis gas can be obtained from natural gas, biomass and even CO2 and

renewable H2, Fischer-Tropsch synthesis also provides an industrial scale

path to renewable liquid fuels and base chemicals. The selectivity between

these fuels and various base chemicals is governed by the sequence of C-O

scission, C-C coupling and hydrogenation/dehydrogenation steps. Insight

into the factors controlling this sequence will provide guidelines to design

more active, stable, and selective catalysts, the ultimate goal in catalysis

research.

Catalyst design and kinetic modeling often start from molecular-scale

hypotheses about the reaction mechanism, the structure of the active sites

and the nature of the rate and selectivity determining steps. These concepts

are hard to evaluate experimentally since molecules are nearly impossible

to observe. Computational catalysis has therefore become a crucial tool to

analyze molecular-scale concepts and elucidate their electronic origin. In

combination with characterization and experimental kinetic validation,

insights gained from computational catalysis can be translated all the way

to the industrial scale, as we have demonstrated for several important

reactions.

Program

Literature study on FTS mechanisms on different catalysts.

Computational catalysis for several key steps (CO scission, C-C

coupling and (de)hydrogenation) on Rh and Ru catalysts and

comparison with Co.

Extend the existing Co-based microkinetic model to Rh and Ru

catalysts to evaluate the effect of the catalyst choice on the product

selectivity.

Formulate guidelines to design catalysts with controllable selectivity.

Doelstelling:

The mechanism of Fischer-Tropsch synthesis (FTS), the conversion of CO

and H2 to a wide range of hydrocarbons and oxygenates, remains intensely

debated. Insight into the mechanism will provide opportunities to control

selectivity. In this project, we conduct a mechanistic study of FTS on

ruthenium and rhodium catalysts using computational catalysis.

Locatie:

Website:


17803: Microkinetics for methane dry reforming over Fe-Ni-

(M)/MgAl2O4


Begeleider(s):

Contactpersoon: Stavros-Alexandros Theofanidis

Goedgekeurd

voor:



technologie

Niet behouden

voor:

Nog onbeslist

voor:

Aantal studenten: 1

Aantal

masterproeven: 1

Probleemstelling:

Justification

Methane dry reforming (DRM) has been a subject of several studies. The

H2/CO ratio from DRM is more favorable for Fischer-Tropsch and

methanol synthesis than the ratio obtained from classical steam reforming.

Moreover, DRM has the lowest operating cost among these processes and

offers the additional advantage of converting CO2 into valuable chemicals.

Fe-Ni catalysts recently prepared via incipient wetness impregnation

method demonstrate improved performance in DRM and motivate

systematic research into the origin of their catalytic properties. It has been

reported that the process of dry reforming over Fe-Ni could be described

by the Mars van Krevelen mechanism where CO2 oxidizes Fe to FeOx,

and CH4 is activated on Ni sites to form H2 and surface carbon. The latter

was re-oxidized by lattice oxygen from FeOx producing CO. However, the

detailed mechanism of methane dry reforming awaits clarification.

Resolving mechanistic details of this behavior will improve our

understanding of DRM reaction on supported Fe-Ni-(M) catalysts and may

lead to better catalyst designs. The questions raised will be addressed by

modelling the experimental data obtained from Temporal Analysis of

Products (TAP) reactor. The latter is recognized as an important

experimental method for heterogeneous catalytic reaction studies. A TAP

pulse response experiment consists of injecting a very small amount of gas,

typically nanomoles per pulse, into a tubular fixed bed reactor that is kept

under vacuum. The time-dependent exit flow rate of each gas is detected

by a mass spectrometer. The high time resolution of the TAP technique

allows detection of short-( millisecond time scale) and/or long-lived (>1s)

reaction intermediates, which helps to formulate the mechanism of

reaction. Microkinetic modeling of transient phenomena enables obtaining

valuable rate coefficients for the elementary steps that often cannot be

determined from steady state experiments. A microkinetic model will

attempt to connect the available surface physicochemical property of the

catalyst, the reaction network and the experimental data.

Program

Transient experiments of methane dry reforming over Ni-, Fe-Ni and

Fe-Ni-Pd catalysts supported on MgAl2O4

Development of a detailed mechanism for methane dry reforming.

Development of microkinetic model using TAPFIT software.

Analysis of the dependency of the catalytic behavior on the catalyst

descriptors providing information about the optimum catalyst

composition and fraction of the active component exposed.

Doelstelling:

The goal of this master thesis is to investigate the mechanism of methane

dry reforming reaction over a Fe-Ni-(M=Pd, Rh and Pt)/MgAl2O4

catalyst.

Locatie:

Technologiepark 914,9052 Gent

Website:


17302: Modeling of non-isothermal controlled radical

polymerization reactors

Promotor(en): Paul Van Steenberge, Dagmar D'hooge

Begeleider(s):

Contactpersoon: Paul Van Steenberge

Goedgekeurd

voor:



technologie

Niet behouden

voor:

Nog onbeslist

voor:

Aantal studenten: 1

Aantal

masterproeven: 1

Probleemstelling:

Justification

Controlled radical polymerization (CRP), e.g. NMP (Figure 1), has

received a lot of attention during the past decades. These polymerization

techniques allow the synthesis of well-tailored next-generation specialty

copolymer architectures due to a better control over molecular parameters,

such as chain length, functionality and topology. Numerous publications

have been attributed to understanding the kinetics behind these complex

polymerization systems at lab-scale under mostly isothermal conditions.

However, less attention has been given to the reactor design, simulation,

optimization and control of these CRPs under industrial conditions, which

involve intensive heat transfer and stirrer work. The study of CRPs in

reactors and their non-isothermal operation is an important requirement for

CRP processes to find their way into large scale commercial products.

Challenges encountered in industrial CSTRs encompass multiplicity of

steady states (extinction and ignition) due to high activation energies, low

reactor inlet temperatures, and possibly near-adiabatic operation.

Challenges encountered in industrial batch and tubular reactors encompass

hot spots (ignition) due to parametric sensitivity.

Figure 1: Principle of nitroxide mediated polymerization (NMP).

Program

1) Literature survey on CRPs on the (isothermal) lab-scale and on the (non-

isothermal) industrial scale, with a focus on non-isothermicity.

2) Extending the current LCT deterministic modeling framework with an

enthalpy balance and reactor equation for several reactor configurations.

3) Studying the NMP carried out in CSTRs focusing on the effect of

multiplicity of steady states on the polymer properties.

4) Studying the NMP carried out in tubular reactors focusing on the effect

of parametric sensitivity on the polymer properties.

5) Identifying stability and runaway criteria for CRP reactor design for the

production of polymer products with a controlled microstructure.

Doelstelling:

In this master thesis, an available modeling platform for the simulation of

isothermal nitroxide mediated polymerization (NMP) will be extended

toward the simulation of several industrial reactor types (e.g. tubular and

continuous stirred tank reactor) with focus on the effect of non-

isothermicity. Special attention will be given to reactor design,

optimization and control of these reactor configurations.

Locatie:


Website:


17199: Optimization of catalyst composition and reaction

conditions for Pt-and Pd-based (de)hydrogenation processes


Begeleider(s):

Contactpersoon: Maarten Sabbe

Goedgekeurd

voor:



technologie

Niet behouden

voor:

Nog onbeslist

voor:

Aantal studenten: 1

Aantal

masterproeven: 1

Probleemstelling:

Justification

Catalyst optimization is a very active research field since the first days of

catalyzed chemical processes, aiming at improving the catalyst’s activity,

selectivity and lifetime. Also, chemical reactors and its operating

conditions have been designed to optimize the conversion and selectivity.

Optimization of the catalyst and operating conditions simultaneously is

rarely considered. Such a simultaneous optimization will be most efficient

if a continuous function of the catalyst’s activity and selectivity is

available. But even then, often conflicting objectives need to be optimized.

This is not only related to the usual trade-off between selectivity and

conversion, but particularly when catalyst price is included, multi-objective

optimization, the so-called Pareto optimization, is required.

A continuous function of the catalyst’s thermodynamic and kinetic

parameters as function of catalyst descriptors has already been constructed

for benzene hydrogenation on Pt/Pd based catalysts and non-oxidative

propane dehydrogenation over Pt-based bimetallic catalysts, based on ab

initio calculations. For the latter process, mainly the selectivity to

propylene is a crucial factor in the process, which aims to meet the rising

propylene demand with which a traditional source of steam cracking can

no longer cope. After identifying the most efficient catalyst descriptor

correlations, the correlation can be implemented into existing reactor

simulation code in order to simulate the most optimal catalyst as function

of the operating conditions. If this step is successful, catalyst cost can be

included in the optimization. Finally, the optimization can be extended

from reactor models with an ideal flow pattern to more realistic reactor

models, and the reactor geometry can be varied to optimize the yield of the

desired product.

Program

1. Formulate effective correlations of catalyst activity and selectivity as

function of a practical catalyst descriptor, such as carbon adsorption

strength or metal d-band center

2. Implement the available or obtained correlations into existing (ideal)

reactor simulation code and determine the most optimal catalyst as

function of the operating conditions

3. Perform a multi-objective optimization that includes the catalyst cost

4. Extend the reactor model to one with a realistic flow pattern and

optimize the reactor morphology

Doelstelling:

The simultaneous multi-objective optimization of catalyst composition and

reactor conditions/morphology using a continuous function of the catalyst

properties as function of the composition, applied to benzene

hydrogenation and propane dehydrogenation.

Locatie:


Website:


17266: Process intensification through reactive flow modulation


Begeleider(s):

Contactpersoon: Jens Dedeyne


Niet behouden

voor:



Aantal studenten: 1

Aantal

masterproeven: 1

Probleemstelling:

Justification

Steam cracking of hydrocarbons is an indispensable process in chemical

industry as it is the dominant method for the production of light olefins, the

basic chemical building blocks. To increase the efficiency of this process,

3D turbulators are often introduced to enhance radial mixing and heat

transfer. Improvement of these factors lead to lower coking rates. This is

very important to ethylene producers as coke deposition on the reactor

inner surface reduces heat transfer, leading to higher tube metal

temperatures and higher pressure drops and hence limits the run length. On

the downside, implementation of turbulators leads to a bigger pressure

drop, which implies a decreased selectivity towards the desired light

olefins.

Thanks to ever increasing computational power, it is made possible to

study the effect of 3D geometries with Computational Fluid Dynamics

(CFD). To fully investigate the influence of these turbulators, Large Eddy

Simulations will be an indispensable tool for the determination of the flow

field and associated properties. Validation of these results will be

performed with experimentally obtained data acquired in cooperation with

VKI.

Program

1. Cold flow simulations will be performed, using OpenFOAM, for a

range of turbulator geometries in order select the most promising

geometries.

2. LES simulations will be performed to further fine tune the design

and implementation of these geometries such that overall

performance of the reactor, based on pressure drop and heat transfer,

is improved.

3. Non-reacting flow experiments will be performed on a cold flow

setup for different coil geometries at the VKI. These experiments

will provide validation for the simulation results.

4. Reactive flow simulations will be performed on the most promising

design. Here focus will be on product selectivities at different stages

of the run as well as on the coking behaviour and the overall run

length.

Doelstelling:

The aim of this work is to investigated the short and long term effects of

implementing swirl generating turbulators in tubular reactors, designed for

steam cracking. The influence of the design parameters on heat transfer

and pressure drop will be examined, as well as the coking behaviour of the

enhanced reactor surface.

Locatie:


Website:


17224: Pyrolysis of cyclic and oxygenated compounds: a

combined modelling and experimental study


Begeleider(s):

Contactpersoon: Florence Vermeire

Goedgekeurd

voor:



technologie

Niet behouden

voor:

Nog onbeslist

voor:

Aantal studenten: 1

Aantal

masterproeven: 1

Probleemstelling:

Justification

Reactive delignification of lignocellulosic biomass produces a pulp of

cellulose and hemicellulose that together with lignin oil can successfully be

converted into a mixture of liquid alkanes and naphthenes containing small

amounts of oxygenates. Before the pyrolysis of this mixture can be

modelled, the thermal decomposition of the cyclic structures and

oxygenates needs to be investigated. The combined usage of

experimentally acquired data and a kinetic model developed by means of

automatic network generation tools allows to understand the chemistry

during pyrolysis of model compounds.

Genesys is a recently developed automatic network generation code

integrated with existing open-source chemo-informatics libraries. Today’s

main challenge of automatic network generation is the scarcity of both

thermodynamic data and reaction rate coefficients. In case databases are

lacking for the considered components and reactions, data will be

determined with the use of on-the-fly quantum chemistry calculations.

Program

Literature survey regarding the experimental and modelling studies

for the pyrolysis of oxygenated and cyclic compounds.

Pyrolysis experiments of model compounds on the bench scale set-

up. Data collection under a broad set of experimental conditions in

diluted and undiluted atmospheres.

Automatic generation of a detailed kinetic model for pyrolysis of

these compounds by extending the currently available kinetic model

with Genesys. The missing thermodynamic data and reaction rate

coefficients will be determined with ab initio techniques

implemented in Genesys.

Validation of the developed microkinetic model with the use of the

experimentally acquired data.

Doelstelling:

The aim of this master thesis is to understand the chemistry of the

pyrolysis of cyclic and oxygenated compounds through kinetic modelling

and experimental work.

Locatie:


Website:


16482: Reaction network size control for the heterogeneously

catalyzed conversion of renewable feeds

Promotor(en): Joris Thybaut, Kevin Van Geem

Begeleider(s): Brigitte Devocht

Contactpersoon: Brigitte Devocht

Goedgekeurd

voor:



technologie

Niet behouden

voor:

Nog onbeslist

voor:

Aantal studenten: 1

Aantal

masterproeven: 1

Probleemstelling:

Justification

Automatic reaction network construction and analysis including a

microkinetic assessment of the catalytic conversion of renewable resources

represents a key challenge for the future, sustainable supply of fuels and

chemicals. The transformation of such renewable resources cannot

adequately be described by simple reaction networks. The need for a

methodology that enables the automatic construction of comprehensive

reaction networks for a wide variety of chemistries is evident (Figure 1).

To prevent infinite generation of new reactions and species and to assure

that the reaction network focuses on the most relevant ones, adequate

decision criteria are required to determine which species and reactions

should be accounted for.

Network size control can be achieved either in a rule- or rate-based manner

which can be implemented both a priori or a posteriori. When a compact

reaction network is concerned or the reliability of the kinetic parameters is

limited, it is expected that a posteriori control is the method of choice.

However, for very extensive reaction networks, generating the complete

reaction network may not be feasible. Therefore, it is recommended to

limit the network size a priori and to expand or shift the network

dynamically. Methods such as a rate of production analysis and sensitivity

analysis will be important in this respect.

Thermodynamic properties of the chemical species and intermediates and

the kinetic parameters of the elementary steps are of crucial importance for

the network size control, since these properties govern the observed

reaction rates. Thermochemical and kinetic properties will be determined

on-the-fly, i.e., during the network generation, via group additivity

methods and regression against experimental data.

In this master thesis, the methodology for network size control will be

implemented within the existing network generation software, with a focus

on the link with regression software. Next, the methodology will be

validated against experimental data in the field of renewables valorization.

Program

1. Literature survey on reaction network size control during automatic

network generation.

2. Implementation of the methodology within the existing automatic

network generation software.

3. Validation of the developed methodology against experimental data

in the field of renewables valorization.

Doelstelling:

Implementation of a systematic methodology to adaptively control the

reaction network size during the automatic network generation for the

catalytic conversion of renewable resources

Locatie:


Website:


17274: Reactive CFD Simulations for biomass fast pyrolysis in

Gas Solid Vortex Reactors

Promotor(en): Kevin Van Geem, Geraldine Heynderickx

Begeleider(s):

Contactpersoon: Shekhar Kulkarni

Goedgekeurd

voor:



technologie

Niet behouden

voor:

Nog onbeslist

voor:

Aantal studenten: 1

Aantal

masterproeven: 1

Probleemstelling:

Justification

Biomass fast pyrolysis has become synonymous with renewable energy

source over the last few years. Fast pyrolysis can harvest energy out of

biomass and produce fuel grade liquid, commonly known as bio-oil.

Additionally, commercially valuable chemicals like 4-ethylguaiacol,

furfural, creosol, catechol, etc. are found in the bio-oil fraction coming

from fast pyrolysis, making this process more valuable and attractive.

Though fast pyrolysis can result in as high as 70% bio-oil yield, it is highly

dependent on vapor residence time inside the reactor, heat transfer to the

solid particles and rapid cooling of the generated vapors.

Gas-solid vortex reactors (GSVR) are a new generation of multiphase

reactors having a configuration of rotating beds in static geometry. Very

high tangential gas injection velocities (~80-120 m/s) and momentum

transfer makes the particles rotate inside the reactor in a relatively denser

bed than fluidized beds. High slip velocities (5-6 m/s) as compared to the

conventional reactors like gravitational fluidized bed reactors (1-2 m/s)

result in very high convective heat transfer coefficients (~500-800

W/m2K) in vortex reactors. Due to the higher gas velocities, the residence

time of the gas phase for these reactors is also lower than in the

conventional ones. With these advantages, GSVR makes a suitable

candidate to perform fast pyrolysis of lignocellulosic biomass. The latter

can be studied both experimentally and numerically.

Solid volume fraction field in reactive GSVR

At LCT, we explore vortex reactors through means of CFD simulations in

ANSYS FLUENT. The experimental reactor that will provide the data to

validate the simulation results is already installed and under trial. On the

CFD side, both a cold flow and a hot flow, non-reactive vortex unit has

been tested experimentally and numerically. In this master thesis a

comparable numerical study of the reactive setup will be performed. It will

allow to affirm the GSVR to be a suitable candidate for biomass fast

pyrolysis.

Solid volume fraction field in reactive GSVR

Program

1. Literature study on fast pyrolysis studies in fluidized beds and

GSVRs.

2. Testing various reaction mechanisms for biomass fast pyrolysis from

simple to complex and to validate them using available experimental

data.

3. Study the segregation of various solid fractions (fresh biomass,

partially reacted biomass, char) which have different densities and

particle sizes during biomass pyrolysis.

Study the effect of particle size on biomass fast pyrolysi

Doelstelling:

To perform reactive CFD simulations for biomass fast pyrolysis on the Gas

Solid Vortex Reactor (GSVR) and to compare performances of various

kinetics models.

Locatie:


Website:


17304: Retrieving intrinsic kinetic parameters using pulsed

laser polymerization

Promotor(en): Dagmar D'hooge, Paul Van Steenberge

Begeleider(s):

Contactpersoon: Yoshi Marien

Goedgekeurd

voor:

Master of Science in Chemical Engineering,

Master of Science in de

ingenieurswetenschappen: chemische technologie

Niet behouden

voor:

Nog onbeslist

voor:

Aantal studenten: 1

Aantal

masterproeven: 1

Probleemstelling:

Justification

To optimize existing industrially applied radical polymerization

processes and to develop new polymer materials kinetic modeling is

indispensable. The success of kinetic modeling for these purposes

depends largely on the accuracy of the intrinsic rate coefficients

used. Since the estimation of these coefficients by multi-response

regression to polymerization data is very demanding, the

independent determination of these kinetic parameters is beneficial.

Pulsed laser polymerization (PLP) is one of the most interesting

polymerization methods allowing to follow “single” reactions. PLP

involves a periodic series of laser pulses in which initiator radicals

are formed from a photoinitiator at each pulse (Figure 1; left). A part

of these radicals initiates chain growth, while the other part

undergoes termination with radicals formed at a previous laser pulse.

Depending on the PLP conditions applied and the monomer selected,

the obtained molar mass distribution (MMD) can possess specific

characteristics allowing the determination of certain intrinsic rate

coefficients. For example, under well-chosen PLP conditions the

consecutive inflection points of the PLP MMD (Figure 1; right)

correspond to radicals which have been terminated after one, two, …

pulses. From these inflection points the intrinsic propagation rate

coefficient can be derived.[1] Recently, conditions have also been

identified for the determination of the backbiting rate coefficient.[2]

However, for important side reactions such as β-scission and

macromonomer propagation no such conditions have yet been

determined. In this work, a detailed kinetic Monte Carlo model for

PLP is used to investigate whether certain individual reactions can be

studied using specific PLP conditions.

[1] Y. W. Marien, P. H. M. Van Steenberge, C. Barner-Kowollik,

M.-F. Reyniers, G. B. Marin, D. R. D’hooge, Macromolecules 2017.

[2] Y. W. Marien, P. H. M. Van Steenberge, K. B. Kockler, C.

Barner-Kowollik, M.-F. Reyniers, D. R. D'hooge, G. B. Marin,

Polym. Chem. 2016, 7, 6521.

Figure 1. Radical concentration profile (left) and molar mass

distribution (right) allowing the determination of kp via its inflection

points.

Program

1. Performing a literature study on the available methods for the

determination of individual rate coefficients in (controlled)

radical (co)polymerization and the available PLP data as a

function of the monomer range, focusing in particular on PLP

in aqueous media.

2. An available computer code for the kinetic modeling of PLP is

used to relate specific side reactions to characteristics of the

PLP MMD as a function of the PLP conditions.

3. Simulation of PLP in aqueous media.

4. Extension of the available PLP computer code to penultimate

copolymerization kinetics.

5. Extension of the available PLP computer code to controlled

radical polymerization.

Doelstelling:

The goal of this master thesis is the determination of individual rate

coefficients (e.g. propagation and β-scission) using pulsed laser

polymerization (PLP).

Locatie:


Website:


16700: Role of promoters in Co-based Fischer-Tropsch

synthesis


Begeleider(s):


Goedgekeurd

voor:




Niet behouden

voor:

Nog onbeslist

voor:

Aantal studenten: 1

Aantal

masterproeven: 1

Probleemstelling:

Justification

FTS is an attractive technology to convert natural gas, CO2 and

waste biomass to clean transportation fuels and chemicals. The

process starts from synthesis gas, a mixture of CO and H2, and

produces products ranging from methane to light olefins, long-chain

hydrocarbons and oxygenates, depending on the reaction conditions

and the catalyst material. It is implemented on an immense industrial

scale. Supported cobalt catalysts are often preferred because of their

high activity, selectivity to long-chain hydrocarbons, low CO2

selectivity and low water−gas shift activity.

To improve the activity and selectivity of Co-based FTS catalysts,

small amounts of Mn, Cu, Cl or B promoters are added; however, the

role of these promoters remains poorly understood. To elucidate the

role of promoters, a detailed understanding of their nature, location

and kinetic role under FTS conditions is required.

Catalyst design and kinetic modeling often start from molecular-

scale hypotheses about the structure of the active sites, the reaction

mechanism, and the nature of the rate and selectivity determining

steps. These concepts are hard to evaluate experimentally since

molecules are nearly impossible to observe. Computational catalysis

has therefore become a crucial tool to analyze molecular-scale

concepts and elucidate their electronic origin. In combination with

characterization and experimental kinetic validation, insights gained

from computational catalysis can be translated all the way to the

industrial scale, as we have demonstrated for several important

reactions.

Program

o Literature study on the role of promoters in Co-based FTS.

o Evaluation of the nature and location of the promotors using

computational catalysis for actual FTS conditions.

o Study of the kinetic effect of these promoters on the rate and

selectivity determining steps of FTS.

Doelstelling:

To improve the activity and selectivity of Co-based Fischer−Tropsch

synthesis (FTS) catalysts, small amounts of Mn, Cu or Cl promoters

are added to the catalyst. The role of these promoters (modification

of Co, introduction of new sites, bifunctional?) remains poorly

understood. In this project, we use computational catalysis to

elucidate the role of promoters by determining the nature, location

and kinetic role under FTS conditions.

Locatie:

Website:


17623: Shedding light on Thin Film Solar Cell Performance

through fundamental modelling in SCAPS-1D and the

microKinetic Engine

Promotor(en): Joris Thybaut, Johan Lauwaert

Begeleider(s): Kenneth Toch, Ana Obradović, Samira Khelifi

Contactpersoon: Ana Obradović

Goedgekeurd

voor:




Niet behouden

voor: Master of Science in Electrical Engineering

Nog onbeslist

voor:

Aantal studenten: 1

Aantal

masterproeven: 1

Probleemstelling:

In thin film solar cell technology, materials with Kesterite structure

are very promising, with an efficiency up to 12.6%. In the case of Si-

containing S- or Se-based Kesterite, the band gap can be adjusted

between 1.6-2.1 eV as confirmed by first principle calculations and

optical measurements on single crystals. This will help to pave the

path for this technology to become a suitable top cell candidate for

tandem devices, e.g., based on already available high-efficiency

crystalline silicon (c-Si) bottom cells. Within the European Project

SWiNG (Development of Thin film Solar cells based on WIde band

Gap kesterite absorbers) such a thin film solar cell with a transparent

back contact is produced, see Figure 1, intended to be deposited on

top of the state-of-the-art c-Si solar cell.

To support this development, the performance of these solar cells is

modelled with an in-house developed, user-friendly software

package SCAPS-1D (Solar Cell Capacitance Simulator). SCAPS-1D

provides insights in the working principle of such an advanced stack

of layers as a solar cell. Besides predicting the solar cell

performance, SCAPS-1D can also simulate a lot of the common

characterization techniques, e.g., External Quantum Efficiency,

Capacitance-Profiling and Current-Voltage. As a result, it is widely

used and a valuable tool in designing and understanding solar cells.

Unfortunately, SCAPS-1D needs a tremendous amount of parameters

to describe the physical working principle of the solar cell and,

hence, it is not possible to use it in a regression software tool.

Another in-house developed software package, i.e., microKinetic

Engine (μKE), is typically used in regression and modelling

chemical reaction kinetics. However, during the last years, it has

proven to be a versatile tool in the modelling of solar cell

performance and determining the different parameter values which

largely affect the solar cell performance. The software perfectly

allows to exploit the duality between chemical reaction networks and

electrical circuits.

Doelstelling:

This master-thesis will start from a reliable SCAPS model for a wide

band gap Kesterite solar cell with transparent back contact. The

numerical data for dark and light current voltage curve will be

expanded with extra parasitic current pathways. This model, based

on the SCAPS data with extra mechanisms, will be implemented in

μKE to estimate the impact of different processing on the

performance of the solar cell. Statistical regression will be used to

assign this performance loss or gain to a specific mechanism.

Locatie:

Technologiepark 914 en iGent

Website:


16697: The μ-Kinetic Engine (µKE): towards a versatile tool for

complex feed conversion simulation and parametric

identification

Promotor(en): Joris Thybaut

Begeleider(s):

Contactpersoon: Ana Obradović

Goedgekeurd

voor:




Niet behouden

voor:

Nog onbeslist

voor:

Aantal studenten: 1

Aantal

masterproeven: 1

Probleemstelling:

Justification

Process design, optimization and control are relying more and more

on detailed modeling. Fundamental models, which describe the

occurring phenomena at the elementary step level without assuming

a rate-determining step, provide an unprecedented insight into the

investigated system. An in-house, user-friendly tool has been

developed for such model construction, i.e., the µ-Kinetic Engine

(µKE), aiming at microkinetic modeling of chemical reactions. A

particular focus is on the treatment of catalytic reaction networks

without requiring any programming effort of the end users.

Dedicated modeling tools are required when dealing with complex

feed conversion. Complex feeds involve large reaction networks.

One way to allow describing these large networks is via the

integration of automated reaction network generation (ReNGeP) in

the µKE. A particular feature in the case of complex feeds is that a

significant number of elementary steps is quasi-equilibrated. This

typically results in instabilities in numerical solvers for simulation

purposes. The challenge is to identify the elementary steps that are

quasi-equilibrated and dynamically adapt the corresponding set of

equations to be solved.

On top of this, the µKE’s ability to identify the significant

parameters of non-reactive systems, such as solar cells, will be

assessed with the available experimental data.

Program

o Literature review on automation in regression as applied to

chemical kinetics and beyond

o Analysis of the existing software Fortran codes related to the

µKE, such as ReNGeP for automated reaction network

generation

o Identification and implementation of quasi-equilibrated

reaction steps during regression and dynamical adaptation of

the corresponding equations in the µKE

o Identification of significant parameters in selected solar cell

models by regression

Doelstelling:

Enhancing the efficiency in the coupling between automated

reaction network generation and the µ-Kinetic Engine. Guaranteeing

the stability of the numerical solvers as well as the consistency of the

solutions, specifically for large reaction networks. Identifying

significant parameters in non-reactive systems exhibiting peculiar

similarities with chemical kinetics, such as electronic circuits in solar

cells.

Locatie:


Website:


17060: The role of promoters in copper catalysis

Promotor(en): Joris Thybaut, Mark Saeys

Begeleider(s): Jenoff De Vrieze

Contactpersoon: Jenoff De Vrieze

Goedgekeurd

voor:




Niet behouden

voor:

Nog onbeslist

voor:

Aantal studenten: 1

Aantal

masterproeven: 1

Probleemstelling:

Justification

Hydrogenation reactions are of fundamental importance in the

production of intermediate and fine chemicals. A large number of

chemical processes in the pharmaceutical, agrochemical and

petrochemical industry are based on catalytic hydrogenation using

heterogeneous catalysts. The most commonly applied hydrogenation

catalysts are palladium, platinum and nickel. However, the use of

promoted copper catalysts in hydrogenation has steadily increased.

They exhibit high selectivity towards the cleavage of terminal C-O

bonds and the selective hydrogenation of carbonyl (C=O) groups. In

addition, promoted copper catalysts show excellent performance in

methanol synthesis and the (reverse) water gas shift reaction. This is

quite surprising because unpromoted copper catalysts have a

relatively low reactivity for hydrogenation reactions. The location,

nature and kinetic role of the promoters remain poorly understood.

As a result, a wide range of promoter elements has been investigated

experimentally. These experimental studies showed that chromium,

zinc, cerium and boron are some of the most promising promoters.

To optimize the design of these catalysts and propose alternative

promoter elements that might increase the performance, a detailed

understanding of the role of promoters in copper catalysis is

required.

Insight in the catalyst structure under reaction conditions and in the

reaction mechanism is of vital importance in catalyst design and

optimization. As those concepts are very challenging to determine

via experimental methods only, computational catalysis is recurred

to.

Program

The following activities will be performed during the master thesis:

o A literature review on the use of promoters in copper catalysis

and the application of computational catalysis to study the

effect of promoters in metal catalysis.

o Investigation of the structure of promoted copper catalysts

under hydrogenation conditions.

o Investigation of the role of promotors for key reaction steps

during methanol synthesis and water gas shift.

Doelstelling:

Elucidation of the role of promoters in copper catalyzed reactions.

Investigation of the structure of promoted copper catalysts under

reaction conditions and elucidation of the kinetic role of these

promoters.

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