Mechanistic insights into copper oxides catalyzed bio-based furfural hydrogenation using methanol as in-situ hydrogen donor

In the present study, CuO and Cu 2 O were employed in H-transfer transformation of bio-based furfural (FFR) using methanol as both the solvent and an in-situ hydrogen source , to clearly elucidate the catalytic mechanism of copper oxides (CuO x , x  = 0.5, 1) during the reaction. A number of characterization techniques including XPS , H 2 -TPD, in-situ FTIR, etc., were undertaken to track the state of copper species. Owing to the synergistic effect of in-situ generated H 2 , Cu 0 species and CuO x derived Brønsted/Lewis acid sites, FFR could be efficiently hydrogenated into FA and subsequently deoxygenated into MF in methanol. The combined results from in-situ characterizations and experiments show that the FFR-to-FA (FA, furfuryl alcohol) and FFR-to-MF (MF, 2-methylfuran) conversions largely depended on the hydrogen production capability from methanol reforming and FFR adsorption strength over CuO x . Density functional theory (DFT) calculations demonstrated that the CuO(200) surface revealed lower free energy and energy barriers for methanol reforming and FFR transfer hydrogenation. This study provides a promising guidance for reasonably designing copper-based materials in the hydro-upgrading of bio-based unsaturated molecules into value-added chemicals in methanol without external H 2 supply.