In this study, with zeolite HY as support, ultrasmall Pd and Pt nanoparticles were successfully immobilized into zeolite HY crystals through an optimized impregnation approach. The success of this new approach mainly relied on the selecting appropriate metal precursor to make Pd and Pt element exists with the cation forms, which can facilitate their diffusion into inner channels of zeolite HY through electrostatic attraction and capillary force. Integration of confinement effect of zeolite HY, taking zeolite HY (Si/Al = 3) encapsulation of ultrasmall Pd NPs (Pd@HY-3) as an instance, Pd@HY-3 catalyst exhibited enhanced catalytic selectivity in semihydrogenation of alkynes, in comparison with Pd/HY, Pd/C, Pd/Al2O3 and lindlar catalysts. This improved catalytic selectivity can be attributed to the constrained upright adsorption conformation of reactant alkyne and corresponding product alkene on encapsulated Pd surface to make alkyne adsorption on Pd surface with larger adsorption energy than that of alkene, thus achieving the high catalytic selectivity.

中文翻译：

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通过具有增强的半氢化选择性的浸渍法在沸石 HY 中制备超小且稳定的 Pd 和 Pt 纳米颗粒

在这项研究中，以 HY 沸石为载体，通过优化的浸渍方法成功地将超小 Pd 和 Pt 纳米粒子固定在 HY 沸石晶体中。这种新方法的成功主要取决于选择合适的金属前驱体，使 Pd 和 Pt 元素以阳离子形式存在，这可以促进它们通过静电引力和毛细管力扩散到沸石 HY 的内部通道中。综合分子筛HY的限域效应，以分子筛HY（Si/Al=3）包封超小Pd纳米颗粒（Pd@HY-3）为例，Pd@HY-3催化剂在炔烃半加氢中表现出增强的催化选择性，在与 Pd/HY、Pd/C、Pd/Al2O3 和 lindlar 催化剂的比较。