Mannitol as a novel dopant for Cu/SiO2: A low-cost, environmental and highly stable catalyst for dimethyl oxalate hydrogenation without hydrogen prereduction

It is highly desirable to design efficient and stable Cu-based catalysts for hydrogenation of C-O bonds. However, a lot of superior Cu-based catalysts were reported by doping with other metal species. In this work, a novel Cu/SiO2 catalyst modified with mannitol was prepared by the ammonia evaporation method. Owing to the CO-release occuring during calcination in nitrogen atmosphere, it can directly realize the reduction of the copper species on the surface without using hydrogen for pre-reduction. As a result, the novel Cu/SiO2 catalyst can rapidly achieve optimum activity and exhibit excellent catalytic activity, higher product selectivity and long-term stability (500 h) in dimethyl oxalate hydrogenation reaction. Furthermore, the analysis of the copper species indicated that the copper species on the surface of the catalyst with mannitol calcined in the nitrogen atmosphere were beneficial for generating stable Cu+ species in a weak reduction atmosphere. Therefore, the mannitol modified Cu/SiO2 catalyst can not only achieve comparable catalytic performance with metal-doped catalysts, but also appears economical and promising. (C) 2020 Published by Elsevier Inc.