Deuterium-Hydroxyl Exchange Over Supported Metal Catalysts

Department of Chemistry, University of Rhode Island, Kingston, Rhode Island 02881, U.S.A. Manuscript received 24 April 1978 ; accepted 27 July 1978 The exchange between hydrogen adsorbed on platinum and supported hydroxyl groups has been studied by a temperature programmed exchange technique. It was found that platinum shifted the deuterium-hydroxyl exchange to temperature below those observed for pure γ-alumina or silica. The method by which the catalyst was prepared had a marked effect on the exchange and on the density of hydroxyl groups on the support. In general it was found that impregnation with H2PtCl6 increased the hydroxyl concen­tration in contrast to impregnation with Pt(NH3)2(NO2)2. In order to assess the importance of the metal-support interface in promoting hydrogen atom spillover, the adsorption of hydrogen atoms generated in the gas phase to a variety of oxide supports, reported to be active in promoting hydrogen atom spillover, was studied. it was concluded that hydrogen atom adsorption was insufficient to account for catalytic enhancement due to hydrogen atom migration across the support. In light of our data, it seems likely that catalytic enhancement due to support-adsorbate interactions are limited to the metal-support interface