Pt-modulated Cu/SiO2 catalysts for efficient hydrogenation of CO2-derived ethylene carbonate to methanol and ethylene glycol

Abstract

Copper-based catalysts were widely used in the heterogeneous selective hydrogenation of ethylene carbonate (EC), a key step in the indirect conversion of CO 2 to methanol. However, a high H 2 /EC molar ratio in feed is required to achieve favorable activity and the methanol selectivity still needs to be improved. Herein, we fabricated a series of Pt-modulated Cu/SiO 2 catalysts and investigated their catalytic performance for hydrogenation of EC in a fixed bed reactor. By modulating the Pt amount, the optimal 0.2Pt-Cu/SiO 2 catalyst exhibited the highest catalytic performance with ∼99% EC conversion, over 98% selectivity to ethylene glycol and 95.8% selectivity to methanol at the H 2 /EC ratio as low as 60 in feed. In addition, 0.2Pt-Cu/SiO 2 catalyst showed excellent stability for 150 h on stream over different H 2 /EC ratios of 180-40. It is demonstrated a proper amount of Pt could significantly lower the H 2 /EC molar ratio, promote the reducibility and dispersion of copper, and also enhance surface density of Cu + species. This could be due to the strong interaction of Cu and Pt induced by formation of alloyed Pt single atoms on the Cu lattice. Meanwhile, a relatively higher amount of Pt would deteriorate the catalytic activity, which could be due to the surface coverage and aggregation of active species. These findings may enlighten some fundamental insights for further design of Cu-based catalysts for the hydrogenation of carbon–oxygen bonds.