CO hydrogenation using cobalt/manganese oxide catalysts. Comments on the mechanism of carbon–carbon bond formation

Abstract

A detailed investigation of the mechanism of CO hydrogenation over cobalt/manganese oxide catalyst is described. In particular, the reaction of a range of oxygenated compounds (methanol, ethanol, ethanol, propan-1-ol, propan-2-ol and propanl), diazo compounds (diazoacetaldehyde and ethyldiazoacetate ) is discussed in addition to the use of low concentrations of dioxygen as a molecular probe during CO hydrogenation. The results of this study indicate that hydroformylation of a C₂ surface intermediate cannot account for the high yields of propene and low yields of methane observed with this catalyst. Based on this study a reaction mechanism for carbon–carbon bond formation in the Fischer–Tropsch reaction is proposed involving α- hydroxylated metal-alkyl as an important intermediate, the formation of which involves the coupling of a number of electrophilic and nucleophilic C₁ surface intermediates.