Center for Molecular Modeling - T. Bligaard

Understanding zeolite-catalyzed benzene methylation reactions by methanol and dimethyl ether at operating conditions from first principle microkinetic modeling and experiments

kristof — Tue, 28 Nov 2017 15:22:45 +0000

K. De Wispelaere, J. S. Martínez-Espín, M. J. Hoffmann, S. Svelle, U. Olsbye, T. Bligaard

Catalysis Today

312, 35-43

2018

Abstract

In methanol-to-hydrocarbon chemistry, methanol and dimethyl ether (DME) can act as methylating agents. Therefore, we focus on the different reactivity of methanol and DME towards benzene methylation in H-ZSM-5 at operating conditions by combining first principles microkinetic modeling and experiments. Methylation reactions are known to follow either a concerted reaction path or a stepwise mechanism going through a framework-bound methoxide. By constructing a DFT based microkinetic model including the concerted and stepwise reactions, product formation rates can be calculated at conditions that closely mimic the experimentally applied conditions. Trends in measured rates are relatively well reproduced by our DFT based microkinetic model. We find that benzene methylation with DME is faster than with methanol but the difference decreases with increasing temperature. At low temperatures, the concerted mechanism dominates, however at higher temperatures and low pressures the mechanism shifts to the stepwise pathway. This transition occurs at lower temperatures for methanol than for DME, resulting in smaller reactivity differences between methanol and DME at high temperature. Our theory-experiment approach shows that the widely assumed rate law with zeroth and first order in oxygenate and hydrocarbon partial pressure is not generally applicable and depends on the applied temperature, pressure and feed composition.

DOI

http://dx.doi.org/10.1016/j.cattod.2018.02.042

Private attachment

1-s2.0-S0920586118301159-main.pdf

Modeling Zeolite Catalysis at Operating Conditions by Combining Advanced Molecular Dynamics and Microkinetic Modeling

kristof — Mon, 04 Jun 2018 07:59:26 +0000

K. De Wispelaere, T. Bligaard, V. Van Speybroeck

ISBN/ISSN:

Talk

Conference / event / venue

International Symposium on Zeolites and Microporous Crystals (ZMPC) 2018

Yokohama, Japan

Sunday, 5 August, 2018 to Thursday, 9 August, 2018

Abstract (private)

ZMPC_2018_abstract_KDW.pdf

Effect of anharmonicity on adsorption and reaction thermodynamics on solid surfaces

kristof — Tue, 15 Aug 2017 16:01:32 +0000

K. De Wispelaere, K. T. Lundgaard, J. K. Nørskov, T. Bligaard

ISBN/ISSN:

Poster

Conference / event / venue

SUNCAT Summer Institute 2017: Fundamentals and Applications of Heterogeneous Catalysis

Stanford University, CA, USA

Monday, 14 August, 2017 to Friday, 18 August, 2017

Towards an anharmonic description of entropy

kristof — Tue, 16 May 2017 20:59:41 +0000

K. De Wispelaere, K. T. Lundgaard, J. K. Nørskov, T. Bligaard

ISBN/ISSN:

Poster

Conference / event / venue

SUNCAT Scientific Advisory Board Meeting

Stanford, USA

Thursday, 18 May, 2017 to Friday, 19 May, 2017

Entropy sampling for zeolite-catalyzed reactions at operating conditions

kristof — Wed, 01 Mar 2017 22:51:57 +0000

K. De Wispelaere, T. Bligaard, J. K. Nørskov, V. Van Speybroeck

ISBN/ISSN:

Talk

Conference / event / venue

253rd American Chemical Society Meeting

San Francisco, CA, USA

Sunday, 2 April, 2017 to Friday, 7 April, 2017