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Insight into the Formation and Reactivity of Framework‐Bound Methoxide Species in H‐ZSM‐5 from Static and Dynamic Molecular Simulations
Author(s) -
Van der Mynsbrugge Jeroen,
Moors Samuel L. C.,
De Wispelaere Kristof,
Van Speybroeck Veronique
Publication year - 2014
Publication title -
chemcatchem
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.497
H-Index - 106
eISSN - 1867-3899
pISSN - 1867-3880
DOI - 10.1002/cctc.201402146
Subject(s) - methoxide , chemistry , methanol , dimethyl ether , reactivity (psychology) , metadynamics , sodium methoxide , reaction mechanism , ether , computational chemistry , catalysis , photochemistry , organic chemistry , molecular dynamics , medicine , alternative medicine , pathology
Framework‐bound methoxides occur as intermediates in the stepwise mechanism for zeolite‐catalyzed methylation reactions. Herein, the formation of methoxides from methanol or dimethyl ether in H‐ZSM‐5 is investigated by a combination of static and dynamic simulations, with particular focus on the effect of additional water and methanol molecules on the mechanism and kinetics. Metadynamics simulations allow partitioning the reaction path into distinct phases. Proton transfer from the zeolite to the reactants is found to be the rate‐limiting phase in the methoxide formation. Additional methanol molecules only assist the proton transfer in the methoxide formation from methanol, whereas the reaction from dimethyl ether does not benefit from methanol assistance. Once formed, methoxides are found to be as reactive toward alkene methylation as methanol and dimethyl ether.