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

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.

Medienart:

E-Artikel

Erscheinungsjahr:

2024

Erschienen:

2024

Enthalten in:

Zur Gesamtaufnahme - volume:146

Enthalten in:

Journal of the American Chemical Society - 146(2024), 12 vom: 27. März, Seite 8688-8696

Sprache:

Englisch

Beteiligte Personen:

Wang, Chao [VerfasserIn]
Zheng, Mingji [VerfasserIn]
Hu, Min [VerfasserIn]
Cai, Wenjin [VerfasserIn]
Chu, Yueying [VerfasserIn]
Wang, Qiang [VerfasserIn]
Xu, Jun [VerfasserIn]
Deng, Feng [VerfasserIn]

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Anmerkungen:

Date Revised 27.03.2024

published: Print-Electronic

Citation Status PubMed-not-MEDLINE

doi:

10.1021/jacs.4c01155

funding:

Förderinstitution / Projekttitel:

PPN (Katalog-ID):

NLM369723996