Bugaev Aram L, Usoltsev Oleg A, Guda Alexander A, Lomachenko Kirill A, Brunelli Michela, Groppo Elena, Pellegrini Riccardo, Soldatov Alexander V, van Bokhoven Jeroen A
The Smart Materials Research Institute, Southern Federal University, Sladkova 178/24, Rostov-on-Don, 344090, Russia.
BM23/ID24, European Synchrotron Radiation Facility, 71 avenue des Martyrs, 38043 Grenoble Cedex 9, France.
Faraday Discuss. 2021 May 1;229:197-207. doi: 10.1039/c9fd00139e. Epub 2021 Mar 3.
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.
钯基催化剂在工业规模上用于烃类的选择性氢化。在反应条件下碳化钯和氢化钯相的形成改变了材料的催化性能，这表明原位表征对于确定这两个相的相对比例与催化剂性能之间的关系很重要。我们展示了一种在广泛的乙烯和氢气分压范围内，对工作中的钯基催化剂在乙烯氢化过程中进行的结合了时间分辨的X射线吸收光谱（近边和扩展区域）和X射线衍射的表征。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转变。颗粒的纳米尺寸导致表面和体相碳化物对X射线吸收光谱都有相当大的贡献。在反应过程中，形成了碳化钯，但这并未导致活性损失。在增加氢气分压时，观察到废催化剂中钯晶格的晶胞参数出现异常收缩。
