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QM/MM study of the stability of dimethyl ether in zeolites H-ZSM-5 and H-Y

Nastase, SAF; Catlow, CRA; Logsdail, AJ; (2020) QM/MM study of the stability of dimethyl ether in zeolites H-ZSM-5 and H-Y. Physical Chemistry Chemical Physics 10.1039/d0cp05392a. Green open access

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Abstract

The methanol-to-hydrocarbons (MTH) process transforms C1 carbon sources to higher hydrocarbons, but details of the mechanism that leads to the formation of the first carbon–carbon bond remain unclear. Here, we present a computational investigation of how a crucial intermediate, dimethyl ether (DME), interacts with different zeolite catalysts (H-ZSM-5, H-Y) to gain insight into the initial stages in the MTH process. We use QM/MM computational simulations to model the conversion of methanol to DME in H-ZSM-5, which is a well characterised and important reaction intermediate. We analyse and compare the stability of DME on several acid sites in H-ZSM-5 and H-Y, and show that the more acidic and open “intersection sites” in the H-ZSM-5 framework are able to bond strongest with DME, with complete deprotonation of the acid site occurring. The conversion of methanol to DME in H-ZSM-5 is calculated as requiring a higher activation energy than framework methoxylation, which indicates that a stepwise (indirect) mechanism, through a methoxy intermediate, is the most likely route to DME formation during the initiation of the MTH process.

Type: Article
Title: QM/MM study of the stability of dimethyl ether in zeolites H-ZSM-5 and H-Y
Location: England
Open access status: An open access version is available from UCL Discovery
DOI: 10.1039/d0cp05392a
Publisher version: https://doi.org/10.1039/d0cp05392a
Language: English
Additional information: This article is licensed under a Creative Commons Attribution 3.0 Unported Licence (http://creativecommons.org/licenses/by/3.0/).
UCL classification: UCL
UCL > Provost and Vice Provost Offices > UCL BEAMS
UCL > Provost and Vice Provost Offices > UCL BEAMS > Faculty of Maths and Physical Sciences
UCL > Provost and Vice Provost Offices > UCL BEAMS > Faculty of Maths and Physical Sciences > Dept of Chemistry
URI: https://discovery.ucl.ac.uk/id/eprint/10119826
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