Green and efficient selective hydrogenation of furfural to furfuryl alcohol over hybrid CoOx/Nb2O5 nanocatalyst in water

The selective hydrogenation of the C=O group in biomass-derivate furfural (FF) over noble metal-free catalysts is challenging in aqueous. Herein, a CoOx/Nb2O5 nanostructure catalyst was synthesized for the hydrogenation of FF to furfuryl alcohol (FA). Under optimized conditions, a 95.7% yield of FA was obtained with a TOF of 155.7 h-1, and the kinetic study revealed that the reaction followed a pseudo-first-order pathway with an activation energy of 39.42 kJ mol-1. The catalyst characterization indicated the interaction between Nb2O5 and CoO via the Nb-O-Co bond in CoOx/Nb2O5-ctr, which prevented the further reduction of CoO to metal Co in the catalyst's preparation process. The catalytic mechanism suggested CoO was the dominant hydrogenation/adsorption active, whilst Co3O4 and Nb2O5 assisted the adsorption of FF. Further, DFT calculations verified CoO was the main adsorption site for FF adsorption in CoOx/Nb2O5-ctr. Moreover, CoOx/Nb2O5-ctr showed outstanding recyclability for the selective hydrogenation of FF to FA ever after five runs. This work provides opportunities for the clean conversion of biomass-based FF to FA and infers potential applications of Co for the large-scale hydrogenation of bio-based platform chemicals.