Facile and Optimized Ion-Exchange Method for Synthesizing Low-Cost and Stable Cu/SiO₂ Catalyst for Hydrogenation of Dimethyl Oxalate to Ethylene Glycol

A low-cost and stable Cu/SiO2 catalyst with a commercial SiO2 sphere support was designed and prepared for vapor-phase hydrogenation of dimethyl oxalate (DMO) to ethylene glycol (EG). By simply thermal pretreatment before ion exchange, the catalytic performance and long-term stability of the optimized O-IE-Cu/SiO2 catalyst are dramatically improved. A DMO conversion of 100% and an EG selectivity of 96% were obtained at 185 °C for over 450 h. Characterization revealed that the remarkably enhanced catalytic performance could be attributed to the high Cu atom utilization efficiency, which was associated with the generation of copper phyllosilicates and sufficient utilization of silanol (Si–OH) groups on the surface of SiO2 induced by the thermal pretreatment. The formation of abundant Si–O–Cu units stemmed from copper phyllosilicates, and ion exchange dramatically enhanced the metal–support interaction, inhibited the growth of copper species, and finally improved the Cu0 dispersion and Cu+/(Cu0 + Cu+) ratio. Therefore, this work provides a facile and low-cost approach for designing stable copper-based catalysts and has considerable reference value for their practical application in the catalytic hydrogenation of DMO to EG.