Hydrogenation on Supported Lanthanide–Palladium Bimetallic Catalysts: Appearance of Considerable Hydrogen Uptake

Abstract

Abstract Upon introducing of lanthanide metals (Ln : Eu or Yb) onto a Pd surface by the reaction of Pd/SiO2 with Eu or Yb metal dissolved in liquid ammonia, the ability of considerable hydrogen uptake by the catalyst appeared during the hydrogenation reaction. Hydrogenation over supported lanthanide–palladium bimetallic catalysts was studied at 173—213 K, especially concerning the effects of the reactants, support materials, Pd particle sizes, and dispersion on the hydrogenation behavior with the hydrogen uptake. For the hydrogenation of ethene, propene, butene or butadiene, considerable hydrogen uptake occurred preferentially, followed by hydrogenation using the hydrogen taken up the catalyst. The hydrogenation occurred by a rate-limited hydrogen uptake process. In marked contrast to olefin and butadiene, no hydrogen uptake was observed for the hydrogenation of acetylene, indicating the progress of the reaction by a different mechanism. The support materials (SiO2, Al2O3, ZrO2, MgO, and TiO2), Pd particle sizes and Pd dispersion in Pd/support were important factors in determining the hydrogen uptake by supported Ln–Pd catalysts and the resulting hydrogenation behavior.