The Regulation of Surface Copper Species Coupled with Ammonia-Evaporation and Hydrothermal Aging Process to Enhance Catalytic Hydrogenation Properties of Cu–SiO2 Catalysts

The ammonia-evaporation method is one of the most commonly methods for preparing Cu–SiO 2 catalysts, and the improvement of this method is desirable. This work showed that it could improve the catalytic performance of the Cu–SiO 2 catalyst in the hydrogenation of dimethyl oxalates (DMO) to ethylene glycol by introducing hydrothermal aging process and adjusting the aging time after evaporated ammonia. There was no obvious effect on copper phyllosilicate formation with the hydrothermal aging time increasing, but it affected the dispersion of Cu 0 species among the copper phyllosilicate layers. As the number of Cu 0 species is enough on the catalyst surface, the density of surface Cu 0 species would affect the synergistic effect between Cu 0 and Cu 0 active sites. It is possible that the DMO absorbed on the Cu + species would be inhibited while the density of surface Cu 0 species is highly. Thus, the modified Cu–SiO 2 catalyst by hydrothermal aging process with relatively low Cu 0 dispersion exhibited enhanced catalytic performance in DMO catalytic hydrogenation. Graphical Abstract