A well-defined catalyst with platinum (Pt) and gold (Au) encapsulated in micropore and mesopore of micro-mesoporous zeolite (Pt-Au/TMSN), respectively, was designed to investigate the original active sites of semi-hydrogenation. Specifically, hydrogen molecules are dissociated on Pt nanoclusters (NCs) to form hydrogen atoms that migrate to the surfaces of TMSN zeolite and Au nanoparticles (NPs) through hydrogen spillover effect. The characterization and catalytic results demonstrate that the Au NPs and zeolite surface are both identified as the semi-hydrogenation sites. Especially, the Au active site with low adsorption ability of alkene possesses preferable selectivity in the semi-hydrogenation of phenylacetylene and 1,5-cyclooctadiene. Noteworthy, the Pt-Au/TMSN exhibits higher selectivity of phenylethylene and cyclooctene than Pt/TMSN, as well as higher turnover frequency than Au/MSN. This work creates an effective regulation strategy of active sites working with a tandem mechanism for improving the semi-hydrogenation performance.

中文翻译：

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对氢溢出下半加氢双区协同催化剂活性位点的洞察

一种定义明确的催化剂，铂 (Pt) 和金 (Au) 分别封装在微介孔沸石 (Pt-Au/TMSN) 的微孔和中孔中，旨在研究半氢化的原始活性位点。具体来说，氢分子在 Pt 纳米团簇 (NCs) 上解离形成氢原子，通过氢溢出效应迁移到 TMSN 沸石和 Au 纳米粒子 (NPs) 的表面。表征和催化结果表明，Au NPs 和沸石表面均被确定为半氢化位点。特别是，具有低烯烃吸附能力的Au活性位点在苯乙炔和1,5-环辛二烯的半加氢反应中具有较好的选择性。值得注意的是，Pt-Au/TMSN 表现出比 Pt/TMSN 更高的苯乙烯和环辛烯选择性，以及比 Au/MSN 更高的周转频率。这项工作创建了一种有效的活性位点调节策略，采用串联机制提高半氢化性能。