Reduced oxygen-deficient CuWO₄ with Ni catalyzed selective hydrogenolysis of cellulose to ethylene glycol

The effective and selective conversion of cellulose to valuable fuels and chemicals is highly attractive. In this paper, we prepared a catalyst with the adjacent surface Cu° and oxygen-deficient WO_x (2 < x < 3) species by reduction of CuWO₄ precursor, and such catalyst coupled with Ni/activated carbon (AC) attained high yield (71 wt%) and good cycling performances in catalyzing one-step hydrothermal conversion of cellulose to ethylene glycol (EG), highly superior to the performances on physically mixed Ni/C, Cu/C and WO₃. The increased Cu doping amounts led to a higher ratio of the lower valence state W (V or IV) to the high valence W(VI) as indicated by XPS, XRD, and TPR-H₂ analyses. The oxygen vacancies on the hydrogen-reduced CuWO₄ sample dramatically increased, probably due to the benefits from the substantial dissociated H• on the neighboring Cu° center. The EG yields from cellulose are shown to be proportional to the concentrations of oxygen vacancies on WO_x, which catalyzes the important elementary retro-aldol step reaction via adsorbing C₆ sugar intermediates in a specific way.