Methanol to dimethyl ether over ZSM-22: A periodic density functional theory study

Poul Georg Moses*, Jens K. Nørskov

*Corresponding author for this work

Research output: Contribution to journalJournal articleResearchpeer-review

Abstract

Methanol-to-DME conversion over ZSM-22 Brønsted acid sites is investigated on the basis of periodic density functional theory calculations. DME formation has been speculated to take place via the dissociative or associative pathway. It is shown that the dissociative pathway is the predominant pathway. We find that water lowers the activation energies of key reactions but that the lowering of the activation energies is insufficient to increase the rate because of the entropy loss associated with water adsorption. The consequence of acid strength on the methanol-to-DME conversion pathways is investigated on the basis of Al-, Ga-, or In-induced Brønsted acid sites. We show that linear correlations between activation energies and acid strength exist. It is found that weaker acidity leads to higher activation energies. We find that changes in acidity will not change the conclusion that the dissociative pathway is the predominant pathway.

Original languageEnglish
JournalACS Catalysis
Volume3
Issue number4
Pages (from-to)735-745
Number of pages11
ISSN2155-5435
DOIs
Publication statusPublished - 2013
Externally publishedYes

Keywords

  • Acidity
  • DME,DFT
  • Kinetics
  • Zeolites
  • ZSM-22

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