The strong acidity on the external surface of ZSM-5 is a primary factor resulting in the low BTX selectivity and catalyst deactivation during the olefin aromatization. In this study, a membrane-restricted Silicalite-1@ZSM-5 core–shell structured catalytic catalyst was designed and constructed for 1-hexene aromatization using a hydrothermal coating method. TEM and NMR results confirmed the complete coverage of Silicalite-1 on the surface of ZSM-5, with a shell thickness of 50 nm. The further reaction of the TIPB (1,3,5-triisopropylbenzene) molecular probe reactions demonstrated the passivation of the acid sites on ZSM-5 external surface. The inert shell layer passivated the acid sites on the external surface, thereby suppressing the isomerization of PX and the side-chain alkylation reaction of light aromatics. Compared to ZSM-5, the Silicalite-1@ZSM-5 catalyst exhibited a 37.15 % increase in BTX selectivity, a 58.65 % increase in PX selectivity, significantly reduced coke deposition, and demonstrated better stability. This strategy of in-situ epitaxial growth of inert shell layers holds significant promise for enhancing the selectivity of shape-selective catalysts and extending catalyst lifetime.

中文翻译：

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核壳结构Silicalite-1@ZSM-5催化剂上1-己烯选择性芳构化生成BTX


ZSM-5外表面的强酸性是导致烯烃芳构化过程中BTX选择性低和催化剂失活的主要原因。在这项研究中，采用水热涂层方法设计并构建了一种膜限制的Silicalite-1@ZSM-5核壳结构催化催化剂，用于1-己烯芳构化。 TEM 和 NMR 结果证实 Silicalite-1 完全覆盖 ZSM-5 表面，壳厚度为 50 nm。 TIPB（1,3,5-三异丙基苯）分子探针反应的进一步反应证明了ZSM-5外表面酸性位点的钝化。惰性壳层钝化了外表面的酸性位点，从而抑制了PX的异构化和轻芳烃的侧链烷基化反应。与ZSM-5相比，Silicalite-1@ZSM-5催化剂的BTX选择性提高了37.15%，PX选择性提高了58.65%，积炭显着减少，稳定性更好。这种惰性壳层原位外延生长策略对于提高择形催化剂的选择性和延长催化剂寿命具有重要前景。