Targeted Dealumination via In Situ Activation of Persulfate in Size-Selective Zeolite Channels

TL;DR

A new method selectively removes aluminum from specific channels in zeolites to improve catalytic performance.

Contribution

A persulfate-based dealumination strategy enables targeted modification of zeolite channels.

Findings

Selective dealumination preserves Al in 8-ring channels while removing it from 12-ring channels.

The method improves catalyst longevity without sacrificing activity in dimethyl ether carbonylation.

Advanced techniques confirm the effectiveness of the strategy in modifying zeolite structures.

Abstract

Selective modification of zeolite structure at specific
sites is
crucial for optimizing catalytic performance. Tailoring the framework
aluminum (Al) siting within particular channels is highly desired
but remains challenging. Here, we introduce a persulfate-based dealumination
strategy that enables selective removal of Al atoms through in situ
activation and zeolite size-selective features. By delivering persulfate
molecules into the 12-ring channels of mordenite zeolite, the method
employs mild thermal treatment to activate these molecules, releasing
etching species that preferentially remove Al from the 12-ring channels
while preserving Al sites in the 8-ring channels. Such selective dealumination
enhances catalyst longevity while maintaining high catalytic activity
in the dimethyl ether carbonylation reaction. The strategy’s
effectiveness is confirmed through a combination of advanced characterization
techniques, including in situ synchrotron X-ray diffraction, in situ
high-energy X-ray total scattering, and probe-assisted solid-state
nuclear magnetic resonance. This pioneering approach opens new opportunities
for designing tailor-made zeolite structures for advanced catalytic
applications.

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