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π-Interactions between Cyclic Carbocations and Aromatics Cause Zeolite Deactivation in Methanol-to-Hydrocarbon
Chao Wang1, Min Hu1,2, Yueying Chu1
1National Center for Magnetic Resonance in Wuhan, State Key Laboratory of Magnetic Resonance and Atomic and Molecular Physics, Key Laboratory of Magnetic Resonance in Biological Systems, Wuhan Institute of Physics and Mathematics, Innovation Academy for Precision Measurement Science and Technology, Chinese Academy of Sciences, Wuhan, 430071, P. R. China.
Abstract:
The understanding of catalyst deactivation represents one of the major challenges for the methanol-to-hydrocarbon (MTH) reaction over acidic zeolites. Here we report the critical role of intermolecular π-interactions in catalyst deactivation in the MTH reaction on zeolites H-SSZ-13 and H-ZSM-5. π-interaction-induced spatial proximities between cyclopentenyl cations and aromatics in the confined channels and/or cages of zeolites are revealed by two-dimensional solid-state NMR spectroscopy. The formation of naphtalene as a precursor to coke species is favored due to the reaction of aromatics with the nearby cyclopentenyl cations and correlates with both acid density and zeolite topology.
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