Insight of the methanol-to-DME reaction from descriptor-based microkinetic modelling
Conference contribution, 2018

Using a descriptor-based approach to study the methanol-to-DME reaction in zeotypes from first-principles, we investigate the different reaction mechanism through a microkinetic model. This theoretical study focuses on Brønsted acidic zeotype catalysts. We demonstrate that the shift in OH stretch frequency with and without CO adsorbed on the site is a good descriptor for the strength of the acid site. Different zeotypes were studied, namely CHA, BEA and MFI zeolite frameworks, where besides conventional Al exchange, we also consider B, Ga and Fe, along with SAPO-34, Mg-AlPO-34, Zn-AlPO-34, and Ti-AlPO-34. These span a wide range of strength of the acidic sites. The top figure shows the free energy landscape for the two main reaction mechanisms for BEA and B-BEA (which have quite different acidity), namely the concerted where two methanol molecules adsorb simultaneously to form DME and water, and the stepwise where one methanol dissociates to a methyl group, producing water.
The bottom figure shows the calculated turn-over frequency (TOF) for the two mechanisms as a function of temperature. This shows that the concerted
mechanism is dominating at lower temperatures while the stepwise dominates at higher temperatures for both systems.

DFT

Micro-kinetic modelling

Catalysis

Zeolites

Methanol-to-DME

Author

Adam Arvidsson

Chalmers, Physics, Chemical Physics

Philipp N. Plessow

Karlsruhe Institute of Technology (KIT)

Anders Hellman

Chalmers, Physics, Chemical Physics

Felix Studt

Karlsruhe Institute of Technology (KIT)

European Conference On Surface Science, ECOSS 34
Aarhus, Denmark,

Time-resolved in situ methods for design of catalytic sites within sustainable chemistry

Swedish Research Council (VR), 2013-01-01 -- 2016-12-31.

Driving Forces

Sustainable development

Areas of Advance

Nanoscience and Nanotechnology (SO 2010-2017, EI 2018-)

Energy

Materials Science

Subject Categories

Physical Chemistry

Theoretical Chemistry

Organic Chemistry

Roots

Basic sciences

Infrastructure

C3SE (Chalmers Centre for Computational Science and Engineering)

More information

Latest update

7/27/2020