Palladium-based catalysts are exploited on an industrial scale for the selective hydrogenation of hydrocarbons. The formation of palladium carbide and hydride phases under reaction conditions changes the catalytic properties of the material, which points to the importance of operando characterization for determining the relation between the relative fractions of the two phases and the catalyst performance. We present a combined time-resolved characterization by X-ray absorption spectroscopy (in both near-edge and extended regions) and X-ray diffraction of a working palladium-based catalyst during the hydrogenation of ethylene in a wide range of partial pressures of ethylene and hydrogen. Synergistic coupling of multiple techniques allowed us to follow the structural evolution of the palladium lattice as well as the transitions between the metallic, hydride and carbide phases of palladium. The nanometric dimensions of the particles resulted in the considerable contribution of both surface and bulk carbides to the X-ray absorption spectra. During the reaction, palladium carbide is formed, which does not lead to a loss of activity. Unusual contraction of the unit cell parameter of the palladium lattice in the spent catalyst was observed upon increasing hydrogen partial pressure.

中文翻译：

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钯上乙烯的加氢：基于操作同步加速器的技术演变催化剂结构

钯基催化剂已在工业规模上用于烃的选择性加氢。钯碳化物和氢化物相的反应条件下形成的改变了材料的催化性能，这点的重要性operando用于确定两相的相对分数与催化剂性能之间关系的表征。我们通过在广泛的乙烯分压下乙烯加氢过程中的工作钯基催化剂的X射线吸收光谱法（在近边缘和扩展区域）和X射线衍射，给出了时间分辨的组合表征和氢。多种技术的协同耦合使我们能够追踪钯晶格的结构演变以及钯的金属，氢化物和碳化物相之间的过渡。颗粒的纳米尺寸导致表面碳化物和块状碳化物对X射线吸收光谱的显着贡献。在反应过程中，形成碳化钯，这不会导致活动损失。在增加的氢气分压下，观察到废催化剂中钯晶格的晶胞参数异常收缩。