Influence of Acidity on the Methanol-to-DME Reaction in Zeotypes: A First Principles-Based Microkinetic Study
Artikel i vetenskaplig tidskrift, 2020

Acidity is considered a key factor in zeotype-based catalysts. Here, the effect of acidity in the methanol-to-DME reaction is investigated using first-principles calculations and microkinetic modeling, thereby establishing a connection between acididity and kinetics. The CHA, MFI, and BEA frameworks are investigated, and the acidity of the Brønsted hydroxyl group is varied by exchanging a T-site Si with Al, B, Ga, and Fe in the zeolites, along with SAPO-34, Mg-AlPO-34, Zn-AlPO-34, and Ti-AlPO-34 zeotypes with the CHA structure, and as a result, the Brønsted hydroxyl group spans a wide range of acidity. Clear trends in adsorption and transition-state energies are found and by means of linear regression, we obtain scaling relations of relevant energies that are later used as input in a mean-field steady-state microkinetic model. This study confirms that both the shift in frequency of the Brønsted hydroxyl stretch, ΔfOH, caused by adsorption of CO and the ammonia adsorption energy, ΔEammonia, on the Brønsted site are equivalent descriptors for the acidity of the Brønsted acid site and the reactivity of the different zeotypes relevant for the methanol-to-DME reaction. It further shows that a full microkinetic model is needed to accurately describe the reaction over the whole range of temperatures. However, if focusing on low temperatures, where the associative mechanism is dominating the reaction, a simple rate-determining step model is actually able to describe the results with satisfying agreement (deviation of the rate by less than a factor of two).

Författare

Adam Arvidsson

Chalmers, Fysik, Kemisk fysik

Philipp N. Plessow

Karlsruher Institut für Technologie (KIT)

Felix Studt

Karlsruher Institut für Technologie (KIT)

Anders Hellman

Chalmers, Fysik, Kemisk fysik

Journal of Physical Chemistry C

1932-7447 (ISSN) 1932-7455 (eISSN)

Vol. 124 27 14658-14663

Ämneskategorier

Oorganisk kemi

Fysikalisk kemi

Annan fysik

Drivkrafter

Hållbar utveckling

Styrkeområden

Nanovetenskap och nanoteknik (SO 2010-2017, EI 2018-)

Transport

Energi

Materialvetenskap

Infrastruktur

C3SE (Chalmers Centre for Computational Science and Engineering)

DOI

10.1021/acs.jpcc.0c03125

Mer information

Senast uppdaterat

2020-09-18