A comparative study of the adsorption and hydrogenation of acrolein on Pt(1 1 1), Ni(1 1 1) film and Pt–Ni–Pt(1 1 1) bimetallic surfaces

Abstract

In this study we have investigated the reaction pathways for the decomposition and hydrogenation of acrolein (CH 2 CH−CH O) on Ni/Pt(1 1 1) surfaces under ultra-high vacuum (UHV) conditions using temperature programmed desorption (TPD) and high-resolution electron energy loss spectroscopy (HREELS). While gas-phase hydrogenation products are not observed from clean Pt(1 1 1), the subsurface Pt–Ni–Pt(1 1 1), with Ni residing below the first layer of Pt, is active for the self-hydrogenation of the C O bond to produce unsaturated alcohol (2-propenol) and the C C bond to produce saturated aldehyde (propanal), with the latter being the main hydrogenation product without the consecutive hydrogenation to saturated alcohol. For a thick Ni(1 1 1) film prepared on Pt(1 1 1), the self-hydrogenation yields for both products are lower than that from the Pt–Ni–Pt(1 1 1) surface. The presence of pre-adsorbed hydrogen further enhances the selectivity toward C O bond hydrogenation on the Pt–Ni–Pt(1 1 1) surface. In addition, HREELS studies of the adsorption of the two hydrogenation products, 2-propenol and propanal, are performed on the Pt–Ni–Pt(1 1 1) surface to identify the possible surface intermediates during the reaction of acrolein. The results presented here indicate that the hydrogenation activity and selectivity of acrolein on Pt(1 1 1) can be significantly modified by the formation of the bimetallic surfaces.