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

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 Cu degrees 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 Cu degrees and Cu+ species and the suitable proportion of Cu+/(Cu++Cu degrees). It was proposed that the Cu degrees species promoted the dissociation of H-2, 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. (C) 2016 Hydrogen Energy Publications LLC. Published by Elsevier Ltd. All rights reserved.