Modulating Copper Dispersion and Active Cu0/Cu+ Sites in Cu/CeO2 Catalysts Through Controlled Calcination Atmosphere for Efficient 5-Hydroxymethylfurfural Hydrogenation

2,5-Bis(hydroxymethyl)furan (BHMF) is a promising intermediate for the synthesis of pharmaceuticals and crown ethers, whereas achieving a high reaction rate in the hydrogenation of 5-hydroxymethylfurfural (5-HMF) to form BHMF remains challenge. In this work, a series of Cu/CeO 2 –x catalysts ( x denotes H, Air, Ar) were synthesized by calcination under different atmospheres (10% H 2 /Ar, Air, Ar) and evaluated for the 5-HMF hydrogenation to BHMF. Cu/CeO 2 –Ar exhibited a superior reaction rate of 26.8 mmol·g cat −1 ·h −1 and BHMF yield of 99.1% under the condition (180°C, 5 h, 1 MPa H 2 ), significantly outperforming Cu/CeO 2 –H and Cu/CeO 2 –Air. The characterizations reveal that the calcination in the oxygen-deficient argon atmosphere led to high Cu dispersion and minimized Cu particle size in the Cu/CeO 2 –Ar. These properties resulted in the abundant Cu + –O V –Ce 3+ sites and increased Cu 0 number. In situ Fourier transform infrared spectroscopy analysis elucidates the distinct roles of these active sites. Cu + sites are responsible for perpendicular adsorption of the 5-HMF carbonyl group, and Cu 0 sites drive efficient H 2 dissociation. In contrast, the O V –Ce 3+ sites do not adsorb 5-HMF and H 2 . The close synergy between numerous Cu 0 sites and abundant Cu + sites in the Cu/CeO 2 –Ar accelerates the process of 5-HMF hydrogenation to BHMF. Graphical The oxygen-deficient argon atmosphere led to high dispersion and small particle size of Cu in Cu/CeO 2 –Ar. These properties resulted in the abundant Cu + sites for the adsorption of CO from 5-HMF and the numerous Cu 0 sites to efficiently dissociate H 2 , synergistically boosting catalytic reaction rate to 26.8 mmol·g cat -1 ·h -1 .