First-principles-based microkinetics simulations of synthesis gas conversion on a stepped rhodium surface

I.A.W. Filot, R.J.P. Broos, J.P.M. van Rijn, G.J.H.A. van Heugten, R.A. Santen, van, E.J.M. Hensen

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The kinetics of synthesis gas conversion on the stepped Rh(211) surface were investigated by computational methods. DFT calculations were performed to determine the reaction energetics for all elementary reaction steps relevant to the conversion of CO into methane, ethylene, ethane, formaldehyde, methanol, acetaldehyde, and ethanol. Microkinetics simulations were carried out based on these first-principles data to predict the CO consumption rate and the product distribution as function of temperature. The elementary reaction steps that control the CO consumption rate and the selectivity were analyzed in detail. Ethanol formation can only occur on the stepped surface, because the barrier for CO dissociation on Rh terraces is too high; step-edges are also required for the coupling reactions. The model predicts that formaldehyde is the dominant product at low temperature, ethanol at intermediate temperature, and methane at high temperature. The preference for ethanol over long hydrocarbon formation is due to the lower barrier for C(H) + CO coupling as compared with the barriers for CHx + CHy coupling reactions. The C(H)CO surface intermediate is hydrogenated to ethanol via a sequence of hydrogenation and dehydrogenation reactions. The simulations show that ethanol formation competes with methane formation at intermediate temperatures. The rate-controlling steps are CO oxidation to create empty sites for the dehydrogenation steps in the reaction sequence leading to ethanol, CHxCHyO hydrogenation for ethanol formation, and CH2 and CH3 hydrogenation for methane formation. CO dissociation does not control the overall reaction rate on Rh. The most important reaction steps that control the selectivity of ethanol over methane are CH2 and CH3 hydrogenation as well as CHCH3 dehydrogenation.
TaalEngels
Pagina's5453-5467
Aantal pagina's15
TijdschriftACS Catalysis
Volume5
Nummer van het tijdschrift9
DOI's
StatusGepubliceerd - 2015

Vingerafdruk

Rhodium
Synthesis gas
Carbon Monoxide
Ethanol
Methane
Hydrogenation
Dehydrogenation
Formaldehyde
Temperature
Ethane
Acetaldehyde
Hydrocarbons
Computational methods
Discrete Fourier transforms
Reaction rates
Methanol
Ethylene
Oxidation
Kinetics

Citeer dit

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title = "First-principles-based microkinetics simulations of synthesis gas conversion on a stepped rhodium surface",
abstract = "The kinetics of synthesis gas conversion on the stepped Rh(211) surface were investigated by computational methods. DFT calculations were performed to determine the reaction energetics for all elementary reaction steps relevant to the conversion of CO into methane, ethylene, ethane, formaldehyde, methanol, acetaldehyde, and ethanol. Microkinetics simulations were carried out based on these first-principles data to predict the CO consumption rate and the product distribution as function of temperature. The elementary reaction steps that control the CO consumption rate and the selectivity were analyzed in detail. Ethanol formation can only occur on the stepped surface, because the barrier for CO dissociation on Rh terraces is too high; step-edges are also required for the coupling reactions. The model predicts that formaldehyde is the dominant product at low temperature, ethanol at intermediate temperature, and methane at high temperature. The preference for ethanol over long hydrocarbon formation is due to the lower barrier for C(H) + CO coupling as compared with the barriers for CHx + CHy coupling reactions. The C(H)CO surface intermediate is hydrogenated to ethanol via a sequence of hydrogenation and dehydrogenation reactions. The simulations show that ethanol formation competes with methane formation at intermediate temperatures. The rate-controlling steps are CO oxidation to create empty sites for the dehydrogenation steps in the reaction sequence leading to ethanol, CHxCHyO hydrogenation for ethanol formation, and CH2 and CH3 hydrogenation for methane formation. CO dissociation does not control the overall reaction rate on Rh. The most important reaction steps that control the selectivity of ethanol over methane are CH2 and CH3 hydrogenation as well as CHCH3 dehydrogenation.",
author = "I.A.W. Filot and R.J.P. Broos and {van Rijn}, J.P.M. and {van Heugten}, G.J.H.A. and {Santen, van}, R.A. and E.J.M. Hensen",
year = "2015",
doi = "10.1021/acscatal.5b01391",
language = "English",
volume = "5",
pages = "5453--5467",
journal = "ACS Catalysis",
issn = "2155-5435",
publisher = "American Chemical Society",
number = "9",

}

First-principles-based microkinetics simulations of synthesis gas conversion on a stepped rhodium surface. / Filot, I.A.W.; Broos, R.J.P.; van Rijn, J.P.M.; van Heugten, G.J.H.A.; Santen, van, R.A.; Hensen, E.J.M.

In: ACS Catalysis, Vol. 5, Nr. 9, 2015, blz. 5453-5467.

Onderzoeksoutput: Bijdrage aan tijdschriftTijdschriftartikelAcademicpeer review

TY - JOUR

T1 - First-principles-based microkinetics simulations of synthesis gas conversion on a stepped rhodium surface

AU - Filot,I.A.W.

AU - Broos,R.J.P.

AU - van Rijn,J.P.M.

AU - van Heugten,G.J.H.A.

AU - Santen, van,R.A.

AU - Hensen,E.J.M.

PY - 2015

Y1 - 2015

N2 - The kinetics of synthesis gas conversion on the stepped Rh(211) surface were investigated by computational methods. DFT calculations were performed to determine the reaction energetics for all elementary reaction steps relevant to the conversion of CO into methane, ethylene, ethane, formaldehyde, methanol, acetaldehyde, and ethanol. Microkinetics simulations were carried out based on these first-principles data to predict the CO consumption rate and the product distribution as function of temperature. The elementary reaction steps that control the CO consumption rate and the selectivity were analyzed in detail. Ethanol formation can only occur on the stepped surface, because the barrier for CO dissociation on Rh terraces is too high; step-edges are also required for the coupling reactions. The model predicts that formaldehyde is the dominant product at low temperature, ethanol at intermediate temperature, and methane at high temperature. The preference for ethanol over long hydrocarbon formation is due to the lower barrier for C(H) + CO coupling as compared with the barriers for CHx + CHy coupling reactions. The C(H)CO surface intermediate is hydrogenated to ethanol via a sequence of hydrogenation and dehydrogenation reactions. The simulations show that ethanol formation competes with methane formation at intermediate temperatures. The rate-controlling steps are CO oxidation to create empty sites for the dehydrogenation steps in the reaction sequence leading to ethanol, CHxCHyO hydrogenation for ethanol formation, and CH2 and CH3 hydrogenation for methane formation. CO dissociation does not control the overall reaction rate on Rh. The most important reaction steps that control the selectivity of ethanol over methane are CH2 and CH3 hydrogenation as well as CHCH3 dehydrogenation.

AB - The kinetics of synthesis gas conversion on the stepped Rh(211) surface were investigated by computational methods. DFT calculations were performed to determine the reaction energetics for all elementary reaction steps relevant to the conversion of CO into methane, ethylene, ethane, formaldehyde, methanol, acetaldehyde, and ethanol. Microkinetics simulations were carried out based on these first-principles data to predict the CO consumption rate and the product distribution as function of temperature. The elementary reaction steps that control the CO consumption rate and the selectivity were analyzed in detail. Ethanol formation can only occur on the stepped surface, because the barrier for CO dissociation on Rh terraces is too high; step-edges are also required for the coupling reactions. The model predicts that formaldehyde is the dominant product at low temperature, ethanol at intermediate temperature, and methane at high temperature. The preference for ethanol over long hydrocarbon formation is due to the lower barrier for C(H) + CO coupling as compared with the barriers for CHx + CHy coupling reactions. The C(H)CO surface intermediate is hydrogenated to ethanol via a sequence of hydrogenation and dehydrogenation reactions. The simulations show that ethanol formation competes with methane formation at intermediate temperatures. The rate-controlling steps are CO oxidation to create empty sites for the dehydrogenation steps in the reaction sequence leading to ethanol, CHxCHyO hydrogenation for ethanol formation, and CH2 and CH3 hydrogenation for methane formation. CO dissociation does not control the overall reaction rate on Rh. The most important reaction steps that control the selectivity of ethanol over methane are CH2 and CH3 hydrogenation as well as CHCH3 dehydrogenation.

U2 - 10.1021/acscatal.5b01391

DO - 10.1021/acscatal.5b01391

M3 - Article

VL - 5

SP - 5453

EP - 5467

JO - ACS Catalysis

T2 - ACS Catalysis

JF - ACS Catalysis

SN - 2155-5435

IS - 9

ER -