Silver-modulated SiO2-supported copper catalysts for selective hydrogenation of dimethyl oxalate to ethylene glycol

We present the application of a one-step urea-assisted gelation method to prepare a SiO2-supported bimetallic catalyst composed of copper (Cu) and silver (Ag). Results show the remarkably enhanced performance of the catalyst for selective hydrogenation of dimethyl oxalate (DMO) to ethylene glycol (EG). Coupled with a series of characterization and kinetic studies, the improved activity is attributed to the formation of Cu nanoparticles containing Ag nanoclusters on the SiO2 surface. The coherent interactions between the Cu and Ag species help create the active Cu+/Cu-0 species in a suitable proportion and prevent the transmigration of bimetallic nanoparticles during the hydrogenation process. The optimized Cu-Ag/SiO2 catalyst with an Ag/Cu atomic ratio of 0.05 has a balanced Cu+/Cu-0 ratio and highly dispersed bimetal particles, which account for its high turnover frequency, EG selectivity of 97.0%, and excellent catalytic stability during the hydrogenation of DMO to EG for longer than 150 h. (C) 2013 Elsevier Inc. All rights reserved.