Hydrogenation of unsaturated hydrocarbons over alkali-metal-modified zinc oxide

Abstract

Superbasic catalytic systems have been obtained by evaporation of alkali metals onto a ZnO surface. The catalysts were characterized by IR and EPR spectroscopy. Similar to the case of alkali-metal-doped oxide insulators, surface colour centres F_s⁺, formed by the trapping of an alkali-atom electron in an oxide anionic vacancy, were identified as the source of the extremely strong one-electron donor properties. The studied catalysts exhibited a much higher activity in the hydrogenation of alkenes than the starting ZnO. A mechanism for propene hydrogenation over the superbasic alkali metal/ZnO system was proposed.