Catalysis by highly diluted Ni + Cu alloy foils: H2–D2 equilibration and ethylene–deuterium exchange reaction

Abstract

The reactions of D₂ with H₂ and with C₂H₄ have been studied over carefully cleaned Ni + Cu alloy foils containing 0.01, 0.1, 1 and 10 atom % Ni. The rate of H₂–D₂ equilibration varied only about ten-fold with Ni content, and the activation energy was constant (22 kJ mol^–1). Surface enrichment by Cu was inferred. With the C₂H₄–D₂ reaction, no ethane was formed, but stepwise exchange to C₂H₃D and HD occurred readily. Multiple exchange in the initial stages was only observable with alloys having 1 and 10 % Ni. The great majority of Ni atoms at the surface appear to be isolated. Attempts to use A.E.S., H₂ and CO chemisorption to assess surface composition were unsuccessful.