Role of Cu in the deuterium addition and exchange of propene over Pd-Cu and Pt-Cu alloy catalysts

Abstract

The reaction intermediate and the reaction mechanism of deuterium addition and exchange of propene over a bimetallic alloy have been studied by microwave spectroscopy as well as by kinetic measurements. The isotopic distribution pattern of monodeuteropropene formed during the reaction changed considerably by alloying Pd or Pt with Cu and resembled that over Cu metal. However, the turnover frequency and apparent activation energy of the overall reaction did not change appreciably by alloying. These results indicate the change in the relative activity of reaction intermediates and suggest an important role of Cu in modifying the active sites and the reaction mechanism. It is proposed that a new type of active site is formed by alloying Group VIII metals with Group IB metals; the interaction may be called the “synergetic ligand effect.”