Cu/SiO 2 catalysts prepared by the ammonia-evaporation method: Texture, structure, and catalytic performance in hydrogenation of dimethyl oxalate to ethylene glycol

Abstract

Cu/SiO 2 catalysts prepared by the ammonia-evaporation (AE) method have been systematically characterized focusing on the effect of the AE temperature during catalyst preparation. It is found that the texture, composition, and structure of the calcined and reduced Cu/SiO 2 catalysts were profoundly affected by the AE temperature. Based on characterizations and previous findings, the copper species on calcined Cu/SiO 2 samples and reduced Cu/SiO 2 catalysts were assigned. In gas-phase hydrogenation of dimethyl oxalate (DMO) to ethylene glycol (EG), the evolution of the catalytic activity with the Cu 0 and Cu + surface areas suggested that Cu + also participated in the hydrogenation process. The cooperative effect between Cu 0 and Cu + is proposed to be responsible for the highest hydrogenation activity of the Cu/SiO 2 catalyst prepared at the AE temperature of 363 K, on which an EG yield of 98% was obtained under the optimized hydrogenation conditions.