Synergistic contribution of metal–acid sites in selective hydrodeoxygenation of biomass derivatives over Cu/CoO_x catalysts

The efficient hydrodeoxygenation (HDO) of biomass derivatives to yield specific products is a significant yet challenging task. In the present study, a Cu/CoO_x catalyst was synthesized using a facile co-precipitation method, and subsequently used for the HDO of biomass derivatives. Under optimal reaction conditions, the conversion of 5-hydroxymethylfurfural reached 100% with a selectivity of ∼99% to 2,5-diformylfuran. In combination with the experimental results, systematic characterizations revealed that CoO_x, as the acid site, tended to adsorb C[dbnd]O bonds, and the metal sites of Cu⁺ were inclined to adsorb C[sbnd]O bonds and enhance C[dbnd]O bond hydrogenation. Meanwhile, Cu⁰ was the main active site for 2-propanol dehydrogenation. The excellent catalytic performance could be attributed to the synergistic effects of Cu and CoO_x. Further, by optimizing the ratio of Cu to CoO_x, the Cu/CoO_x catalysts exhibited notable performance in HDO of acetophenone, levulinic acid, and furfural, which verified the universality of the catalysts in the HDO of biomass derivatives.