Highly dispersed nickel boosts catalysis by Cu/SiO2 in the hydrogenation of CO2-derived ethylene carbonate to methanol and ethylene glycol

Abstract

The efficient hydrogenation of CO 2 -derived ethylene carbonate (EC) to yield methanol (MeOH) and ethylene glycol (EG) is a key process for indirect conversion of CO 2 to MeOH. However, a high H 2 /EC molar ratio during the hydrogenation process (usually as 180–300) is generally required to achieve good catalytic performance, resulting in high cost and energy consumption for H 2 circulation in the promising industrial application. Here, we prepared a series of Ni-modified Cu/SiO 2 catalysts and explored the effects of synthesis methods and Ni contents on catalytic performance under different H 2 /EC molar ratios. The Cu/SiO 2 catalyst with 0.2% (mass) Ni loading prepared by co-ammonia evaporation method exhibited above 99% conversion of EC, 91% and 98% selectivity to MeOH and EG respectively at H 2 /EC ratio of 60. And no significant deactivation was observed within 140 h at a lower H 2 /EC of 40. It is demonstrated that a few of Ni addition could not only promote Cu dispersion and increase surface Cu + species due to the strong interaction between Cu and Ni species, but also form uniformly-dispersed CuNi alloy species and thus enhance the adsorption and dissociation of H 2 . But the excess Ni species would aggregate and segregate to cover partial surface of Cu nanoparticles, leading to a significantly drop of catalytic performance in EC hydrogenation. These insights may provide guidance for further design of catalysts for the ester hydrogenation reactions.