Selective hydrogenation of ethylene carbonate to methanol and ethylene glycol over Cu/SiO2 catalysts prepared by ammonia evaporation method

Abstract

A series of Cu/SiO2-AE catalysts with different copper loadings were prepared by ammonia evaporation method with silica sol as the silica source. The systematic catalyst characterization revealed that different proportions of Cu0 and Cu+ species co-existed in the Cu/SiO2-AE catalysts, which derived from the reduction of CuO and copper phyllosilicate, respectively. The as-prepared catalysts were employed in the hydrogenation of ethylene carbonate (EC) to co-produce methanol (MeOH) and ethylene glycol (EG). Among the catalysts investigated, the 10%Cu/SiO2-AE catalyst with a moderate copper loading exhibited better catalytic activity and product selectivities, which was mainly ascribed to the synergetic effect of Cu0 and Cu+ species and the suitable proportion of Cu+/(Cu++Cu0). It was proposed that the Cu0 species promoted the dissociation of H2, while Cu+ species adsorbed on the carbonyl group of EC. Under the optimized conditions, EC conversion of 100%, MeOH selectivity of 70.8% and EG selectivity of 98.0% were obtained over the 10%Cu/SiO2-AE catalyst. The catalyst reusability results showed that the agglomeration of Cu and Cu2O particles was responsible for the gradually decreasing activity of 10%Cu/SiO2-AE catalyst along with recycling runs.