joris w. thybaut - ugent advisory... · joris w. thybaut 1 methusalemadvisory board meeting, ghent,...
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Laboratory for Chemical Technology, Ghent University
http://www.lct.UGent.be
Joris W. Thybaut
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Methusalem advisory board meeting, Ghent, Belgium, 19 June 2012
Single-Event MicroKinetics (SEMK) in complex
reaction mixtures, catalyst design based on catalyst
descriptors & Adsorption by nanoporous materials
(P1 - P3)
rational catalyst design
Methusalem advisory board meeting, Ghent, Belgium, 19 June 2012
catalyst library activity library
optimizeddescriptors
newconcept
industrialapplication
performance testing
design
synthesis
kinetic and catalystdescriptors
modelling
1
2
3
4
H
H
H
H
H
H
H
H
H
H
H
H
H
H
H
H
H
H
H
H
HH
H H
H
H
H
H
**
*
*
**
*
* *
*
*
*
H
H
H
H
H
H
H
H
H
H
H
*
1
3 6
2 4
5
7
8
9
10
11
12 13k(2,2) k(2,2)
k(2,2)k(2,2)
k(2,2) k(2,2)k(1,2)
k(1,2)
k(1,2)
k(1,2)
k(1,2)
k(1,2)
k(1,2)
k(1,2)
k(0,2) k(0,2)
k(0,2)k(0,2)
k(0,2) k(0,2)
2
Single-Event MicroKinetics (SEMK)
Methusalem advisory board meeting, Ghent, Belgium, 19 June 2012
+ +
reactant 0,# 0,#global b
#
global
σ k T S Hk exp exp
σ h R RT
∆ ∆= −
%
3
rational ZSM-22 design
Methusalem advisory board meeting, Ghent, Belgium, 19 June 2012
related patents:- US20100181229- US20110042267publications:- Hayasaka et al. Chem. Eur. J. (2007)- Choudhury et al. J. Catal. (2012)
0
20
40
60
80
100
423 473 523 573
Iso
mer
Yie
ld /
mo
l%
Temperature / K 4
outline
• introduction• µkinetic engine• catalyst design
– methanol-to-olefins– xylene isomerization/ethylbenzene
dealkylation
• adsorption characterization– hydrocracking– transesterification
• conclusions5
Methusalem advisory board meeting, Ghent, Belgium, 19 June 2012
µkinetic engine: background
• generic methodology for kinetic model construction
• no user intervention is needed in programming
• reaction network is automatically converted into rate equations
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Methusalem advisory board meeting, Ghent, Belgium, 19 June 2012
high-throughput experimentation
microkinetic modeling(includes all elementary steps)
1. optimize catalyst properties and kinetic parameters
2. predict behavior for reactions / compounds of the same family
µkinetic engine: workflow
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Methusalem advisory board meeting, Ghent, Belgium, 19 June 2012
Operating conditions
Experimental data
No. experimentsNo. input variables
No. responsesReactor typeInitial values
DatafileGeneration
Reaction Network
Standalone software tool
Input data
Kinetic parametersStatistical analysis of results
Generate plotsModel predictions
detailed flow scheme
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Methusalem advisory board meeting, Ghent, Belgium, 19 June 2012
• writing section• simulation results• statistical interpretation
• overall information• experimental• regression
• perform simulationfor all experiments
• compare calculatedand experimentaloutlet flow rates
• adjust parameter values
fit ok?yes no
• start main program
• reading section• reaction network
• thermochemistry
• regression section• Rosenbrock• Levenberg-
Marquardt
• thermochemicalcalculations
• parameter constraints
• solution set of equations:
• initialization• integration
calculated versus experimental values
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Methusalem advisory board meeting, Ghent, Belgium, 19 June 2012
WSSQ Weight to the reponse
Experimental flowrates
Error
Parameters to be
estimated
Flowratescalculated using
model
� �� � � �� � ��� � �� ������������
����
��
����
���
solution set of equations: reactor model
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Methusalem advisory board meeting, Ghent, Belgium, 19 June 2012
• Plug Flow reactor (differential equations)
• Continuous Stirred Tank Reactor (algebraic equations)
solution set of equations: kinetic model
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Methusalem advisory board meeting, Ghent, Belgium, 19 June 2012
• net production rate of component i
• reaction rate (A* + B � D*, A*: intermediate, B: response)
• rate coefficient
,=∑αi i j jj
R r
, 1...
( ), 1...
n ms response tot elem steps
j paramete
s
s rs
r p C s nk
j nk f
θβ
= =
= =intermediate
where, αi,j is stoichiometric coefficient of component i in reaction j
1 1exp
ave
as T
ave
Ek k
R T T
= − −
β
solution set of equations
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Methusalem advisory board meeting, Ghent, Belgium, 19 June 2012
• Mass balance for the catalyst’s active sites
• analytical solution only possible for simple reaction mechanisms
• steady state approximation:• intermediates are considered as highly reactive, i.e.,
net rate of formation equals zero:
• DDASPK2.0 used as solver for the set of equations
*totC C C= +∑ intermediate
0R =intermediate
graphical user interface
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Methusalem advisory board meeting, Ghent, Belgium, 19 June 2012
µkinetic engine: summary
• performs microkinetic modeling adopting complex networks in heterogeneous catalysis
• no programming required by the end user
• incorporates differential and algebraic solvers + deterministic & stochastic optimization routines
• able to provide information about quasi-equillibruim steps.
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Methusalem advisory board meeting, Ghent, Belgium, 19 June 2012
µkinetic engine: summary
• reaction orders can also be estimated
• no rate determining step. • able to plot the agreement
between model and experimental data points with residual error and save them as images
• Provide statistical analysis of results:• 95% confidence interval,• t-value, • F value • etc.
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Methusalem advisory board meeting, Ghent, Belgium, 19 June 2012
outline
• introduction• µkinetic engine• catalyst design
– methanol-to-olefins– xylene isomerization/ethylbenzene
dealkylation
• adsorption characterization– hydrocracking– transesterification
• conclusions16
Methusalem advisory board meeting, Ghent, Belgium, 19 June 2012
methanol to olefinsMTO process provides an alternative route to produce olefins/gasoline.
Methanol/Oxygenates
synthesis
Synthesis Gas Production
Coal
Natural gas
Biomass
MTO/MTH
and higher olefins
Methusalem advisory board meeting, Ghent, Belgium, 19 June 2012
17
(*) Formation and consumption of hydrocarbon pool species not considered.
DME Formation
Primary Hydrocarbons Formation
Higher Olefins Formation
CH3OH
DMO+
CH3OH2+
CH4 + HCHO + H+
H+ + DME
CH3+ HYDROCARBON
POOL*
C2=
C3=
C4 Olefinsisomerization
C5 Olefinsisomerization
C6 Olefinsisomerization
C7 Olefinsisomerization
β-s
ciss
ion
Me
thyl
atio
n &
Alk
yla
tion
reaction scheme hydrocarbons over ZSM-5
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Methusalem advisory board meeting, Ghent, Belgium, 19 June 2012
Ethene/Propeneand aromatics
Alkanes
Propene andhigher alkenes
Cyclization and hydride transfers
Toluene
Trimethylbenzene
Exocyclicmethylation
cycle
Alkenehomologation
cycle
Propene
Higher alkenes
MeOH
overall summary of the reaction network
Bjorgen et al., J. Catal. 249 (2007) 19519
Methusalem advisory board meeting, Ghent, Belgium, 19 June 2012
Reaction network on H-ZSM-5 catalyst
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Methusalem advisory board meeting, Ghent, Belgium, 19 June 2012
Surface methoxy and DME formation:2 quasi-equilibrium reactions (protonation of MeOH and DME)2 reversible reactions6 adjustable parametersMethane formation:Irreversible reaction1 adjustable parametersPrimary olefins formation:8 reversible reactions10 adjustable parameters1 total concentration of hydrocarbon poolHigher olefins formation:1 Irreversible reaction (methylation)1 reversible reaction (alkylation)12 adjustable parameters- 6 activation energies based on stability
of carbenium ions-6 olefin protonation enthalpies depending onnumber of carbon atoms from O2 to O7
Reaction network in terms of elementary steps for ZSM-5 catalyst:
Number of Species DME
formation
Primary olefins
formation
Higher olefins
formation
(Cyclic) Olefins/DME/H2O 3 4 50
Carbenium ions 3 5 41
Aromatics 1
Total 6 10 91
Number of elementary steps
Protonation 3 3 71
Deprotonation 3 3 71
Hydride shift 40
Methyl shift 15
PCP branching 54
Methylation 3 22
Demethylation 3
Alkylation 2 15
Dealkylation 2
β-scission 6
hydration 1
dehydration 1
Total 8 16 294
Simulation results
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Methusalem advisory board meeting, Ghent, Belgium, 19 June 2012
Parity diagram of experimental vs calculated outlet MTO products flow rates at T = 360 - 480 0C, Pt = 1.04 bar and W/FMeOH = 0.5 - 6.5 kgcat.s mol-1. line: experimental; ♦: obtained from model regression
model parameter values
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Methusalem advisory board meeting, Ghent, Belgium, 19 June 2012
Activation energy
(kinetic descriptors)
Forward
(kJ/mol)
Reverse
(kJ/mol)
Protonation enthalpy
(catalyst descriptors)
(kJ/mol)
Surface methoxy, and DME formation
Dehydration 222.7±8.1 170.4±15.6 Methanol -61.8±3.8
Protonation with MeOH 138.6±7.5 163.7±14.8 DME -42.8±8.1
Methane formation
Methane formation 121.1±18.4
Hydrocarbon pool species formation
Methylation of p-xylene 101.5±1.1 123.2±17.1
Deprotonation of TMeB+ and DMeEtB+ 156.7+9.6 123.1±16.8
Methylation of DMeMCHDE and DMeEtCHDE 75.5±16.9 151.8±17.4
Dealkylation of DMeEtB+ and PDMeB+ 84.2±8.2 14.1±2.4
Deprotonation of PX+ 143.4±20.8 123.9±16.8
model parameter values
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Methusalem advisory board meeting, Ghent, Belgium, 19 June 2012
Activation energy
(kinetic descriptors)
(kJ/mol) Protonation enthalpy/ CHP
(catalyst descriptors)
(kJ/mol)/(mol/ kgcat)
Methylation (p-p) 131.9±28.2 Ethene -11.1±0.16
Methylation (p-s) 92.8±10.9 Propene -42.5±7.6
Methylation (p-t) 54.9±9.2 Butene -53.9±9.0
Alkylation (s-s) 138.0±9.4 Pentene -61.6±15.1
Alkylation (s-t) 119.7±17.6 Hexene -67.7±2.1
Alkylation (t-s) 167.6±28.6 Heptene -70.3±12.4
CHP(Total concentration of hydrocarbon pool species)
3.47×10-2
Performance curves
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Methusalem advisory board meeting, Ghent, Belgium, 19 June 2012
Experimental and model calculated yield of MTOproducts at T = 400 0C and Pt = 1.04 bar. Symbols:experimentally observed values, ethene (�), propene(▲), butene (■); lines: calculated
Experimental and model calculated yield of MTOproducts at T = 400 0C and Pt = 1.04 bar.Symbols: experimentally observed values,pentene (�), hexene (▲), heptene (■), methane(�); lines: calculated
Experimental and model calculated yield of primaryolefins at methanol conversion = ~65% and Pt = 1.04bar. Symbols: experimentally observed values, ethene(�), propene (▲); lines: calculated
Experimental and model calculated yield of olefinicproducts at T=360 0C, Pt = 1.04 bar and W/FMeOH = 4.28 kgcat.s mol-1.
Contribution analysis
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Methusalem advisory board meeting, Ghent, Belgium, 19 June 2012
Contribution analysis for MTH on H-ZSM-5 catalystat space time of 2.21 kgcat.s/mol and at 400 0C, conversion=66.9%
contribution analysis: temperature effect
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Methusalem advisory board meeting, Ghent, Belgium, 19 June 2012
Contribution analysis MTH on H-ZSM-5 catalystat space time of 1.40 kgcat.s/mol and at 480 0C,conversion=73.6%
Contribution analysis for MTH on H-ZSM-5 catalystat space time of 2.21 kgcat.s/mol and at 400 0C,conversion=66.9%
MTO framework structure effects
ZSM-5 (MFI) ZSM-23 (MTT)
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Methusalem advisory board meeting, Ghent, Belgium, 19 June 2012
interconnected straight and sinusoidal channels
monodimensional, straight channels
contribution analysis: framework effect
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Methusalem advisory board meeting, Ghent, Belgium, 19 June 2012
Contribution analysis for MTO on ZSM-23 catalyst at T= 400 0C and Weff/FMeOH = 24.8 kgcat.smol-1
conversion=50.2%
Contribution analysis for MTH on H-ZSM-5 catalystat space time of 2.21 kgcat.s/mol and at 400 0C,conversion=66.9%
Xylene isomerization on a bifunctional Pt/H-ZSM-5 catalyst
Reaction network consists out of:
• acid catalyzed reactions:
(de-)protonation,
alkyl shift (MS),
dealkylation, (DA)
transalkylation (TA)
• metal catalyzed reactions:
Hydrogenation (HYD)
• physisorption
xylene isomerization: SEMK model
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Methusalem advisory board meeting, Ghent, Belgium, 19 June 2012
CH3
CH3
CH3
CH3
CH3
CH3
CH3
CH3
CH3
CH3
CH3
CH3
CH3
CH3
CH3
CH3
CH3
CH3
CH3
CH3
+
CH3
CH3
+
CH3
CH3
+
CH3
CH3
CH3CH3
CH3
C2H6
CH3+
CH3
CH3 CH3
+
CH3
CH3
CH3
Physisorption
Physisorption
(de-)Protonation
Physisorption
Physisorption
(de-)ProtonationMethylshift
Transalkylation
Dealkylation
(de-
)Hyd
rog
enat
ion
Metal sites Acid sites
Zeolite
CH3
CH3CH3
(de-)Protonation
Chemisorption
Chemisorption
CH3
K. Toch et al. Appl. Catal. A-Gen 425 (2012) 130-144
xylene isomerization: results
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Methusalem advisory board meeting, Ghent, Belgium, 19 June 2012
Successful estimation of the kinetic parameters
• small confidence interval
• physically meaningful
importance of the reactions
HYD << TA << DA ~ MS
order of activation energies:
Ea,DA >> Ea,MS ~ Ea,TA >> Ea,HYD
Successful description of the responses
∆S A
DA > 0 105 Aref Monomolecular
MS 0 Aref Monomolecular
TA < 0 10-3 Aref Bimolecular
HYD - 102 Aref Bimolecular, numberof active sites
K. Toch et al. Appl. Catal. A-Gen 425 (2012) 130-144
xylene isomerization: catalyst optimization
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Methusalem advisory board meeting, Ghent, Belgium, 19 June 2012
acid strength modifications: ∆Hpr is varied from -60 … -110 kJ mol-1
What is of industrial relevance?maximization of PX content minimization of xylene losses maximization of benzene yield
→ definition of profit function Ψ:
→ ∆Hpr(opt) ≈ ∆Hpr(est)
(catalyst used = industrial catalyst)
max →=Ψ ∆ prH
XYL
BPX
X
SATE
0
1000
2000
3000
4000
5000
6000
7000
-110-100-90-80-70-60
Ψ
ΔHpr (kJ mol-1)
633K, 1 MPa
653K, 1 MPa
673K, 1 MPa
0
10
20
30
40
50
60
70
80
90
100
-110-100-90-80-70-60
YB
(%)
ΔHpr (kJ mol-1)
633K, 1MPa
653K, 1MPa
673K, 1MPa
0
20
40
60
80
100
120
-110-100-90-80-70-60
AT
EP
X(%
)
ΔHpr (kJ mol-1)
633K, 1MPa
653K, 1MPa
673K, 1MPa
0
2
4
6
8
10
12
14
16
-110-100-90-80-70-60
XX
YL
(%)
ΔHpr (kJ mol-1)
633K, 1MPa
653K, 1MPa
673K, 1MPa
K. Toch et al. Appl. Catal. A-Gen 425 (2012) 130-144
outline
• introduction• µkinetic engine• catalyst design
– methanol-to-olefins– xylene isomerization/ethylbenzene
dealkylation
• adsorption characterization– hydrocracking– transesterification
• conclusions32
Methusalem advisory board meeting, Ghent, Belgium, 19 June 2012
33
long alkane hydrocracking over BETA
Methusalem advisory board meeting, Ghent, Belgium, 19 June 2012
USY n-octane BETA n-hexadecane
B. Vandegehuchte et al. Appl. Catal. A-Gen (accepted)
shape selectivity
+
+
1,2 alkyl shift
rAS = kAS CR+
kAS = k0 exp-(Ea;AS + ∆Ea)
R TAS
+
+
Ene
rgy
Reaction coordinate
∆Ea
Ea;AS79.8 kJ mol-1
21.9 (± 1.0) kJ mol-1
Transition state shape selectivity duringEthyl branch formation
0.0E+00
5.0E-08
1.0E-07
1.5E-07
2.0E-07
2.5E-07
0.0E+00 5.0E-08 1.0E-07 1.5E-07 2.0E-07 2.5E-07
Fm
od
(mo
l s-1
)
Fexp (mol s-1)
b
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Methusalem advisory board meeting, Ghent, Belgium, 19 June 2012
B. Vandegehuchte et al. Appl. Catal. A-Gen (accepted)
0
10
20
30
40
50
60
70
80
4 6 8 10 12 14
↗
CN ↗
θθθθ ↗
θθθθ ↘
adsorption saturation: size entropy
Krishna et al. Chem. Eng. J., 2002
Entropic effects favor the component with the lowest carbon number atsaturation loadings as smaller molecules fit more easily in the gapswithin the zeolite matrix.
Linear approximation of -∆Ssiz0
= 0
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Methusalem advisory board meeting, Ghent, Belgium, 19 June 2012
B. Vandegehuchte et al. Appl. Catal. A-Gen (accepted)
transesterification
• ethylacetate + methanol over LewatitK1221 (sulphonic acid ion exchange resin)
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Methusalem advisory board meeting, Ghent, Belgium, 19 June 2012
+ +
E. Van de Steene et al. J. Mol. Catal. A-Chem. 359 (2012) 57-68
model discrimination
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Methusalem advisory board meeting, Ghent, Belgium, 19 June 2012
Simulated values (lines) exhibit a good agreement with the experimental results
(temperature effect and initial reactant molar ratio effect)
1
1
SR MeOH MeOH EtOAc MeOAc EtOHeq
MeOH MeOH EtOH EtOH
k K a a a aK
ra K a K
−
=+ +
Kinetic model: ER_MeOH_SR: Eley-Rideal mechanism with the reaction of EtOAc from
the bulk with adsorbed MeOH on the catalyst surface as rate-determining step.
E. Van de Steene et al. J. Mol. Catal. A-Chem. 359 (2012) 57-68
model assessment: reaction mechanism
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Methusalem advisory board meeting, Ghent, Belgium, 19 June 2012
E. Van de Steene et al. J. Mol. Catal. A-Chem. 359 (2012) 57-68
outline
• introduction• µkinetic engine• catalyst design
– methanol-to-olefins– xylene isomerization/ethylbenzene
dealkylation
• adsorption characterization– hydrocracking– transesterification
• conclusions39
Methusalem advisory board meeting, Ghent, Belgium, 19 June 2012
conclusions
• versatility of the SEMK methodology has been demonstrated
• µKE: generic platform has been createdrequiring a minimum user intervention
• zeolite framework and acid strengtheffects have been quantitatively assessed
• peculiar adsorption effects may govern the overall conversion
40
Methusalem advisory board meeting, Ghent, Belgium, 19 June 2012
perspectives
• further integration of tools in the µKE– reaction network generation– thermochemical calculations– benchmarking against the ‘competition’
• ‘Pleiade’ of future applications– methane aromatization– ethylene oligomerization– ethanol to hydrocarbons– aldol condensations– hydroisomerisation including diffusion– … 41
Methusalem advisory board meeting, Ghent, Belgium, 19 June 2012
acknowledgements
• Methusalem program• EC FP7• FWO• IAP• SRF• Shell, BP• …
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Methusalem advisory board meeting, Ghent, Belgium, 19 June 2012
questions?
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Methusalem advisory board meeting, Ghent, Belgium, 19 June 2012