Role of copper content and calcination temperature in the structural evolution and catalytic performance of Cu/P25 catalysts in the selective hydrogenation of dimethyl oxalate

Abstract

A series of Cu-based P25-supported catalysts of copper weight loading ranging from 5% to 30% and calcinated at 623–923K were synthesized via a facile ammonia evaporation method for the selective hydrogenation of dimethyl oxalate (DMO) to ethylene glycol (EG). Copper content and calcination temperature played significant roles in the catalytic process. The catalytic performance increases with growing copper loading, but excessively high copper contents would lead to metal aggregation and thus cause the deactivation of catalyst. Calcination effect illustrates that catalyst calcinated at lower temperature presents relatively weak metal-support interaction, while high temperature (923K) treatment results in collapse of microstructure and crystalline phase transformation of titania support, which further leads to low copper dispersion, metal aggregation and thus poor hydrogenation activity. The 20Cu/P25-823 catalyst with a 20wt.% copper loading and calcined at 823K displays superb catalytic performance and long-term stability of more than 96h, with DMO conversion of 100% and EG selectivity of 99% unchanged.