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Unraveling Spatially Dependent Hydrophilicity and Reactivity of Confined Carbocation Intermediates during Methanol Conversion over ZSM-5 Zeolite

 Date:2024/3/14 14:56:58 Views:Times

Abstract


Carbocations play a pivotal role as reactive intermediates in zeolite-catalyzed methanol-to-hydrocarbon (MTH) transformations. However, the interaction between carbocations and water vapor and its subsequent effects on catalytic performance remain poorly understood. Using micro-magnetic resonance imaging (μMRI) and solid-state NMR techniques, this work investigates the hydrophilic behavior of cyclopentenyl cations within ZSM-5 pores under vapor conditions. We show that the polar cationic center of cyclopentenyl cations readily initiates water nucleus formation through water molecule capture. This leads to an inhomogeneous water adsorption gradient along the axial positions of zeolite, correlating with the spatial distribution of carbocation concentrations. The adsorbed water promotes deprotonation and aromatization of cyclopentenyl cations, significantly enhancing the aromatic product selectivity in MTH catalysis. These results reveal the important influence of adsorbed water in modulating the carbocation reactivity within confined zeolite pores.



Link:https://pubs.acs.org/doi/full/10.1021/jacs.4c01155


中国科学院精密测量科学与技术创新研究院 (中国科学院武汉物理与数学研究所) 邓风课题组
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