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首页> 外文期刊>ACS catalysis >Surface Composition Control of the Binary Au-Ag Catalyst for Enhanced Oxidant-Free Dehydrogenation
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Surface Composition Control of the Binary Au-Ag Catalyst for Enhanced Oxidant-Free Dehydrogenation

机译：二元Au-Ag催化剂的无氧化剂脱氢反应的表面组成控制

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Effective control of surface composition of bimetallic catalysts is challenging yet important, as synergistic effects between two metals play vital roles in heterogeneous catalysis. This study involves methods of loading control, thermal activation, and selective surface etching to modify the bimetallic surface on the Au-Ag/SBA-15 catalyst and gains insight into the nature of the promotional effect of Ag modification over Au catalysts. The binary Au-Ag/SBA-15 catalyst prepared following a stepwise metal-loading procedure is found for the first time to be active in benzyl alcohol dehydrogenation without oxidant or hydrogen acceptor. A direct correlation is established between the surface compositions of the Au-Ag nanoparticles and their intrinsic catalytic activities. Au-Ag element analytical techniques, including X-ray fluorescence, X-ray photoelectron spectroscopy, and high-sensitivity low-energy ion scattering spectroscopy, are applied to acquire compositional information in bulk and on the surface. As a result, the pronounced improvement of Au catalyst by Ag is from an ensemble with a specific surface composition rather than the bulk composition. The synergy between Au and Ag for benzyl alcohol dehydrogenation is the most pronounced in the case of 4:1 Au-Ag surface compositions, corresponding to the prepared Au-1-Ag-0.111, catalyst. The electronic promoting effect is suggested as the natural origin of compositional enhancement by differentiating it from the structural effect. This work demonstrates the importance of surface composition control at an atomic level in developing highly efficient multicomponent catalysts.
机译：有效控制双金属催化剂的表面组成具有挑战性，但很重要，因为两种金属之间的协同作用在非均相催化中起着至关重要的作用。这项研究涉及负载控制，热活化和选择性表面蚀刻的方法，以修饰Au-Ag / SBA-15催化剂上的双金属表面，并深入了解Ag修饰对Au催化剂的促进作用的性质。首次发现按照逐步的金属负载程序制备的二元Au-Ag / SBA-15催化剂在没有氧化剂或氢受体的情况下，在苯甲醇脱氢中具有活性。在Au-Ag纳米颗粒的表面组成与其固有催化活性之间建立了直接的相关性。包括X射线荧光，X射线光电子能谱和高灵敏度低能离子散射光谱的Au-Ag元素分析技术可用于获取大量和表面成分信息。结果，Ag对Au催化剂的显着改进来自具有特定表面组成而不是整体组成的整体。在4：1的Au-Ag表面组成（对应于制得的Au-1-Ag-0.111催化剂）的情况下，Au和Ag之间用于苄醇脱氢的协同作用最为明显。通过将电子促进作用与结构作用区别开来，认为它是组成增强的自然起源。这项工作证明了在开发高效多组分催化剂方面，在原子水平上控制表面组成的重要性。

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