Efficient catalytic hydrogenation of furfural over cobalt-based catalysts with adjustable acidity

The selective hydrogenation/rearrangement of biomass-derived furfural (FF) to value-added products is critical in the development of renewable chemicals. Herein, a bifunctional catalyst comprising CoOx loaded on Nb2O5 by the simple wetness impregnation method was constructed, which showed high activity for FF hydrogenation/rearrangement to achieve cyclopentanone (CPO) and cyclopentanol (CPL). The total yield of CPO and CPL was up to 82% with a 20% CoOx/Nb2O5 catalyst. Catalyst characterization indicated that CoOx was the active site, which is responsible for FF hydrogenation. Furthermore, increasing the catalyst's Brønsted/Lewis acidic sites ratio aided the hydrogenative ring rearrangement. Density functional theory (DFT) verified that CoO has higher adsorption energy than Co3O4, and intermediate products in the rearrangement process, such as 2-pentene-1,4–dione (PED), 4–hydroxy-2-cyclopentenone (HCP), and 2-cyclopentenone (2-CEP) are extremely unstable. Furthermore, the polymer formed during the reaction may result in the deactivation of the CoOx/Nb2O5 catalyst.