Reduction of benzaldehyde on alkaline earth metal oxides

Abstract

Benzaldehyde reduction was studied over alkaline earth metal oxide catalysts and carried out in a nitrogen or a dihydrogen atmosphere at the 100–350 °C of the range reaction temperature. The results show that benzyl alcohol is produced by the Cannizzaro reaction under nitrogen flow on MgO oxide and by direct hydrogenation under dihydrogen on irreducible oxides such as CaO, BaO and SrO. The Cannizzaro reaction involves the basic hydroxyl groups and is followed by the reduction of benzoate species by H 2 to benzaldehyde. Toluene and benzene were produced at high reaction temperature under N 2 flow over alkaline earth oxides from a reaction involving benzylate species. Under H 2 flow, toluene and benzene were also formed by means of consecutive reduction reactions. The present work deals with the acid–base properties of alkaline earth metal oxide catalysts (MgO, CaO, BaO, SrO) and benzaldehyde reduction was used as probe reaction for characterizing the surface properties.