FACULTY OF ENGINEERING ANDFACULTY OF ENGINEERING AND ARCHITECTURE Ethylene Oligomerization on...
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FACULTY OF ENGINEERING AND ARCHITECTURE Ethylene Oligomerization on Bifunctional Heterogeneous Catalysts: Model Development and Catalyst Optimization ARCHITECTURE Model Development and Catalyst Optimization K. Toch, J.W. Thybaut and G.B. Marin E-mail: [email protected] K. Toch, J.W. Thybaut and G.B. Marin Universiteit Gent, Laboratory for Chemical Technology Krijgslaan 281 (S5), 9000 Ghent, Belgium - http://www.lct.UGent.be E-mail: [email protected] Introduction and Objective Experimental Study Modelling Approach: SEMK Valorization of natural gas and biogas by Oxidative Coupling of Methane, followed by Oligomerization to 1.8wt% Ni-SiO 2 -Al 2 O 3 absence of acid catalysis Single-Event MicroKinetics: classification of elementary steps into reaction families Coupling of Methane, followed by Oligomerization to Liquids (OCMOL) [1] Detailed mechanistic → determination of metal-ion kinetics classification of elementary steps into reaction families (energetic/enthalpic considerations) accounting for symmetry effects (entropic consideration) insights lead to an ‘in- silico’ optimization of both the catalyst and 4.89wt% Ni-Beta both metal-ion as acid catalysis pre-exponential factors calculated based on statistical thermodynamics both the catalyst and process conditions applied (Model Based → determination of acid kinetics Operating conditions: activation energies/reaction enthalpies: determined by regression catalyst descriptors: catalyst properties Catalyst Design) [2] Operating conditions: T: 443 – 523 K | p 0 C2 : 1.0 – 3.5 Mpa | W cat /F 0 : 4.0 – 15.0 intrinsic kinetics regime (absence of transport limitations) catalyst descriptors: catalyst properties kinetic descriptors: reaction family properties intrinsic kinetics regime (absence of transport limitations) Metal-ion kinetics determination Acid kinetics determination 1.8wt% Ni-SiO 2 -Al 2 O 3 is highly selective towards dimerization (83-86%) → mainly production butenes C 2 H 4 C H C 2 H 4 C 2 H 4 C 4 H 8 C 2 H 4 ivity 4.89wt% Ni-Beta is highly selective towards dimerization (>80%) → mainly production butenes → mainly production butenes → maximum up to C 8 detected → no odd carbon numbered components Ni + Ni + Ni + Ni + 2 4 C 2 H 4 2 4 2 4 C 4 H 8 Ni + 4 8 ... C 2 H 4 -ion acti insertion chemisorption chemisorption initiation → mainly production butenes → maximum up to C 8 detected → lower activity (≈60%) than 1.8wt% Ni- Product selectivities independent of operating conditions 18 Ni Ni C 2 H 4 C 2 H 4 metal- termination SiO 2 -Al 2 O 3 but : → formation of odd carbon numbered 12 14 16 18 C 4 H 8 C 4 H 8 C 4 H 8 C 8 H 16 H + C 8 H 16 ctivity → formation of odd carbon numbered components (C 3 and C 5 ) Alkylation of C 4 to C 8 , with consecutive 6 8 10 12 Yield (%) Butene Hexene H + H + 4 8 H + 8 16 H alkylation, isomerization ... acid ac alkylation / beta-scission (de-)protonation (de-)protonation Alkylation of C 4 to C 8 , with consecutive cracking to C 3 and C 5 components → selectivity towards C 3 and C 5 : 0.5–2.0% 18 20 22 0 2 4 6 14 16 2 2.5 10 12 14 16 rsion (%) 0 0 5 10 15 20 25 Conversion (%) 10 12 culated (%) 1.5 culated (%) 4 6 8 10 Conver Insertion/termination mechanism inspired by homogeneous polymerization kinetics 6 8 X C2 - calc 0.5 1 S cr - calc 0 2 0 5 10 15 W/F ° (kg cat s mol C2 -1 ) Parameters estimates by regression to 51 exp. data points → significant parameter estimates 4 4 6 8 10 12 14 16 X C2 - experimental (%) 0 0 0.5 1 1.5 2 2.5 S cr - experimental (%) W/F ° (kg cat s mol C2 ) p 0 C2 = 3.5 MPa | : 443 K, : 473 K, : 493 K → significant parameter estimates → adequate model predictions Catalyst descriptors ΔH phys(C2) ΔΔH phys(2C) ΔH chem(C2) Kinetic descriptors E a,ins E a,ter Catalyst descriptors ΔH phys(C2) ΔΔH phys(2C) ΔH chem(C2) ΔH pr Kinetic descriptors E a,alk C2 cr Catalyst descriptors ΔH phys(C2) ΔΔH phys(2C) ΔH chem(C2) Kinetic descriptors E a,ins E a,ter Est. value (kJ mol -1 ) -7.2 ± 0.2 -12.3 ± 0.4 -49.9 ± 0.6 Est. value (kJ mol -1 ) 76.3 ± 0.6 67.8 ± 0.6 Catalyst descriptors ΔH phys(C2) ΔΔH phys(2C) ΔH chem(C2) ΔH pr Kinetic descriptors E a,alk Est. value (kJ mol -1 ) -4.9 ± 1.7 -9.9 ± 2.6 -39.3 ± 0.7 -46.6 ± 18.9 Est. value (kJ mol -1 ) 65.1 ± 22.5 phys: physisorption, chem: chemisorption, ins: insertion, ter: termination phys: physisorption, chem: chemisorptio, pr: protonation, alk: alkylation ‘In Silico’ Catalyst Development ‘In Silico’ Catalyst Development The SEMK model for ethylene oligomerization, including the kinetic 2.5 5.00 descriptors, as ‘engine’ of the catalyst development tool Adjustable parameters: → catalyst descriptors, c.q., catalyst properties 2 %) Gasoline Propylene 3.00 4.00 y (%) Gasoline Propylene → catalyst descriptors, c.q., catalyst properties → reaction conditions Objective function defined on economic relevant base 1 1.5 ectivity (% 2.00 3.00 electivity Objective function defined on economic relevant base e.g., maximization of the yield of gasoline or propylene 0.5 Sele 1.00 Se 0 423 473 523 573 623 673 723 773 Temperature (K) 0.00 10 30 50 70 90 ΔH pr (kJ mol -1 ) Low temperature: only metal-ion catalyzed reactions Temperature (K) Ni-Beta studied, p 0 C2 = 3.5 MPa, W cat /F 0 = 1.0 kg cat s mol C2 -1 modified Ni-Beta, T = 573 K, p 0 C2 = 3.5 MPa, W cat /F 0 = 1.0 kg cat s mol C2 -1 however: Simultaneous determination of catalyst properties and Future Work Conclusions Low temperature: only metal-ion catalyzed reactions High temperature: increasing importance of cracking Simultaneous determination of catalyst properties and reaction conditions is a difficult optimization problem Expand the experimental dataset on the Ni-Beta Future Work Conclusions Ni-SiO 2 -Al 2 O 3 and Ni-Beta allowed to investigate resp. the metal-ion and acid catalyzed Expand the experimental dataset on the Ni-Beta → increased insight in the effect of the reaction conditions on the catalyst’s activity → input for the kinetic model Ni-SiO 2 -Al 2 O 3 and Ni-Beta allowed to investigate resp. the metal-ion and acid catalyzed oligomerization kinetics in detail Ni-SiO 2 -Al 2 O 3 studied is more active than Ni-Beta Expand and refine the kinetic model → more significant determination of catalyst and kinetic descriptors Use the refined kinetic model as ‘engine’ for the catalyst development tool 2 2 3 → lower chemisorption enthalpy of ethylene → lower physisorption enthalpies of the olefins Catalyst descriptors were determined significant [1] http://www .ocmol.eu Use the refined kinetic model as ‘engine’ for the catalyst development tool → determine a full set of optimal catalyst properties and reaction conditions for different, economic relevant, objective functions, e.g., maximized gasoline yield Catalyst descriptors were determined significant Optimal reaction conditions and catalyst properties determination using the tool is possible This presentation reports work undertaken in the context of the project “OCMOL, Oxidative Coupling of Methane followed by Oligomerization to Liquids” . OCMOL is a Large Scale Collaborative Project supported [1] http://www .ocmol.eu [2] J.W. Thybaut, I.R.Choudhury, J.F. Denayer, G.V. Baron, P.A. Jacobs, J.A. Martens and G.B.Marin, Top. Catal. (52) 1251 - 1260 different, economic relevant, objective functions, e.g., maximized gasoline yield by the European Commission in the 7th Framework Programme (GA n°228953). For further information about OCMOL see: http://www.ocmol.eu or http://www.ocmol.com.
Transcript of FACULTY OF ENGINEERING ANDFACULTY OF ENGINEERING AND ARCHITECTURE Ethylene Oligomerization on...
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FACULTY OF ENGINEERING ANDARCHITECTURE
Ethylene Oligomerization on Bifunctional Heterogeneous Catalysts:Model Development and Catalyst Optimization
ARCHITECTURE
Model Development and Catalyst OptimizationK. Toch, J.W. Thybaut and G.B. Marin E-mail: [email protected]. Toch, J.W. Thybaut and G.B. Marin
Universiteit Gent, Laboratory for Chemical Technology Krijgslaan 281 (S5), 9000 Ghent, Belgium - http://www.lct.UGent.be
E-mail: [email protected]
Introduction and Objective Experimental Study Modelling Approach: SEMK
� Valorization of natural gas and biogas by Oxidative
Coupling of Methane, followed by Oligomerization to
Introduction and Objective Experimental Study Modelling Approach: SEMK
1.8wt% Ni-SiO2-Al2O3absence of acid catalysis
Single-Event MicroKinetics:� classification of elementary steps into reaction families Coupling of Methane, followed by Oligomerization to
Liquids (OCMOL)[1]
� Detailed mechanistic
absence of acid catalysis
→ determination of metal-ion kinetics
� classification of elementary steps into reaction families
(energetic/enthalpic considerations)
� accounting for symmetry effects (entropic consideration)� Detailed mechanistic
insights lead to an ‘in-
silico’ optimization of
both the catalyst and
4.89wt% Ni-Beta
both metal-ion as acid catalysis
� accounting for symmetry effects (entropic consideration)
� pre-exponential factors calculated based on statistical
thermodynamicsboth the catalyst and
process conditions
applied (Model Based
both metal-ion as acid catalysis
→ determination of acid kinetics
Operating conditions:
� activation energies/reaction enthalpies: determined by
regression
� catalyst descriptors: catalyst propertiesapplied (Model Based
Catalyst Design)[2] Operating conditions:
T: 443 – 523 K | p0C2: 1.0 – 3.5 Mpa | Wcat/F0: 4.0 – 15.0
intrinsic kinetics regime (absence of transport limitations)
� catalyst descriptors: catalyst properties
� kinetic descriptors: reaction family propertiesintrinsic kinetics regime (absence of transport limitations)
Metal-ion kinetics determination Acid kinetics determination
� 1.8wt% Ni-SiO2-Al2O3 is highly selective
towards dimerization (83-86%)
→mainly production butenesC2H4
C HC2H4C2H4 C4H8C2H4
met
al-io
n ac
tivity
�4.89wt% Ni-Beta is highly selective towards
dimerization (>80%)
→mainly production butenes→mainly production butenes
→ maximum up to C8 detected→ no odd carbon numbered components
Ni+
Ni+ Ni
+
Ni+
C2H4C2H4
C2H4C2H4C4H8
Ni+
C4H8
...
C2H4
met
al-io
n ac
tivity
insertion
chemisorptionchemisorptioninitiation
→mainly production butenes
→ maximum up to C8 detected→ lower activity (≈60%) than 1.8wt% Ni-→ no odd carbon numbered components
� Product selectivities independent of operating
conditions18
Ni NiC2H4 C2H4
met
al-io
n ac
tivity
termination
→ lower activity (≈60%) than 1.8wt% Ni-SiO2-Al2O3
but:
→ formation of odd carbon numbered
12
14
16
18
C4H8C4H8
C4H8C8H16 H
+
C8H16
acid
act
ivity
→ formation of odd carbon numbered components (C3 and C5)
� Alkylation of C4 to C8, with consecutive
6
8
10
12
Yie
ld (
%)
Butene
Hexene
H+
H+
C4H8
H+
C8H16 H
alkylation, isomerization ...
acid
act
ivity
alkylation / beta-scission
(de-)protonation
(de-)protonation� Alkylation of C4 to C8, with consecutive
cracking to C3 and C5 components
→ selectivity towards C3 and C5: 0.5–2.0%
18
20
22
0
2
4
6
14
16
2
2.5
10
12
14
16
18
Co
nv
ers
ion
(%
)
0
0 5 10 15 20 25
Conversion (%)10
12
calc
ula
ted
(%
)
1.5
2
calc
ula
ted
(%
)
4
6
8
10
Co
nv
ers
ion
(%
)
� Insertion/termination mechanism inspired by
homogeneous polymerization kinetics6
8
XC
2-
calc
ula
ted
(%
)
0.5
1S
cr-
calc
ula
ted
(%
)
0
2
0 5 10 15
W/F° (kgcat s molC2-1)
� Parameters estimates by regression to 51 exp.
data points
→ significant parameter estimates
4
6
4 6 8 10 12 14 16
XC2 - experimental (%)
0
0 0.5 1 1.5 2 2.5
Scr - experimental (%)W/F° (kgcat s molC2 )
p0C2 = 3.5 MPa | �: 443 K, �: 473 K, �: 493 K
→ significant parameter estimates→ adequate model predictions
Catalyst descriptors ΔHphys(C2) ΔΔHphys(2C) ΔHchem(C2) Kinetic descriptors Ea,ins Ea,ter Catalyst descriptors ΔHphys(C2) ΔΔHphys(2C) ΔHchem(C2) ΔHpr Kinetic descriptors Ea,alk
XC2 - experimental (%) Scr - experimental (%)
Catalyst descriptors ΔHphys(C2) ΔΔHphys(2C) ΔHchem(C2) Kinetic descriptors Ea,ins Ea,ter
Est. value (kJ mol-1) -7.2 ± 0.2 -12.3 ± 0.4 -49.9 ± 0.6 Est. value (kJ mol-1) 76.3 ± 0.6 67.8 ± 0.6
Catalyst descriptors ΔHphys(C2) ΔΔHphys(2C) ΔHchem(C2) ΔHpr Kinetic descriptors Ea,alk
Est. value (kJ mol-1) -4.9 ± 1.7 -9.9 ± 2.6 -39.3 ± 0.7 -46.6 ± 18.9 Est. value (kJ mol-1) 65.1 ± 22.5
phys: physisorption, chem: chemisorption, ins: insertion, ter: termination phys: physisorption, chem: chemisorptio, pr: protonation, alk: alkylation
‘In Silico’ Catalyst Development‘In Silico’ Catalyst Development
� The SEMK model for ethylene oligomerization, including the kinetic 2.5
5.00
� The SEMK model for ethylene oligomerization, including the kinetic
descriptors, as ‘engine’ of the catalyst development tool
�Adjustable parameters:
→ catalyst descriptors, c.q., catalyst properties
2
Se
lect
ivit
y (
%)
Gasoline
Propylene3.00
4.00
Se
lect
ivit
y (
%)
Gasoline
Propylene
→ catalyst descriptors, c.q., catalyst properties→ reaction conditions
�Objective function defined on economic relevant base1
1.5
Se
lect
ivit
y (
%)
2.00
3.00
Se
lect
ivit
y (
%)
�Objective function defined on economic relevant base
e.g., maximization of the yield of gasoline or propylene0.5
1
Se
lect
ivit
y (
%)
1.00
Se
lect
ivit
y (
%)
0
423 473 523 573 623 673 723 773
Temperature (K)
0.00
10 30 50 70 90
ΔHpr (kJ mol-1)
�Low temperature: only metal-ion catalyzed reactions
Temperature (K)
Ni-Beta studied, p0C2 = 3.5 MPa, Wcat/F0 = 1.0 kgcat s molC2
-1
pr
modified Ni-Beta, T = 573 K, p0C2 = 3.5 MPa, Wcat/F0 = 1.0 kgcat s molC2
-1
however:
� Simultaneous determination of catalyst properties and
Future WorkConclusions
�Low temperature: only metal-ion catalyzed reactions
� High temperature: increasing importance of cracking
� Simultaneous determination of catalyst properties and
reaction conditions is a difficult optimization problem
� Expand the experimental dataset on the Ni-Beta
Future WorkConclusions
� Ni-SiO2-Al2O3 and Ni-Beta allowed to investigate resp. the metal-ion and acid catalyzed � Expand the experimental dataset on the Ni-Beta
→ increased insight in the effect of the reaction conditions on the catalyst’s activity→ input for the kinetic model
� Ni-SiO2-Al2O3 and Ni-Beta allowed to investigate resp. the metal-ion and acid catalyzed
oligomerization kinetics in detail
� Ni-SiO2-Al2O3 studied is more active than Ni-Beta
� Expand and refine the kinetic model
→ more significant determination of catalyst and kinetic descriptors
� Use the refined kinetic model as ‘engine’ for the catalyst development tool
� Ni-SiO2-Al2O3 studied is more active than Ni-Beta
→ lower chemisorption enthalpy of ethylene → lower physisorption enthalpies of the olefins
� Catalyst descriptors were determined significant
[1] http://www.ocmol.eu
� Use the refined kinetic model as ‘engine’ for the catalyst development tool
→ determine a full set of optimal catalyst properties and reaction conditions for different, economic relevant, objective functions, e.g., maximized gasoline yield
� Catalyst descriptors were determined significant
� Optimal reaction conditions and catalyst properties determination using the tool is possible
This presentation reports work undertaken in the context of the project “OCMOL, Oxidative Coupling of Methane followed by Oligomerization to Liquids”. OCMOL is a Large Scale Collaborative Project supported
[1] http://www.ocmol.eu
[2] J.W. Thybaut, I.R. Choudhury, J.F. Denayer, G.V. Baron, P.A. Jacobs, J.A. Martens and G.B. Marin, Top. Catal. (52) 1251 - 1260
different, economic relevant, objective functions, e.g., maximized gasoline yield
This presentation reports work undertaken in the context of the project “OCMOL, Oxidative Coupling of Methane followed by Oligomerization to Liquids”. OCMOL is a Large Scale Collaborative Project supported
by the European Commission in the 7th Framework Programme (GA n°228953). For further information about OCMOL see: http://www.ocmol.eu or http://www.ocmol.com.
