Cu/CexZr10-x Derived from Zr-Incorporated Ce-MOF with Tunable Oxygen Vacancies and Acid Sites for Efficient Selective Hydrodeoxygenation of 5-HMF to 2,5-DMF

In heterogeneous catalysis research, a significant challenge is to elucidate how metallic copper (Cu0) and cuprous (Cu+) phases interact with their supporting materials, with a special emphasis on how oxygen vacancy (OV) sites participate in hydrogenation processes. In this work, Cu/CexZr10-x catalysts were prepared by introducing Zr-incorporated Ce-MOF, followed by copper impregnation and calcination. Characterization by TEM, XPS, EPR, H2-TPD, Py-IR spectroscopy, and in situ FTIR revealed that Zr doping enhanced the OV concentration, stabilized Cu+ species, and generated abundant Lewis acid sites. The optimal Zr content effectively balances the Cu0/Cu+ redox couples and acid sites, accelerating desired reactions, while excessive Zr incorporation leads to increased Brønsted acidity and promotes undesirable side reactions. These features synergistically enhance the adsorption of 5-HMF, activate carbonyl groups, and facilitate the sequential hydrogenation and deoxygenation processes, thereby achieving 5-HMF fully converted and achieving a 2,5-DMF selectivity of 98.2% under optimal reaction parameters. This study clarifies the cooperative mechanism among Cu active sites, OV, and acid sites in the conversion of 5-HMF and demonstrates that rational Zr incorporation in MOF-derived Cu/CexZr10-x catalysts can precisely modulate surface properties and significantly improve catalytic performance. These findings offer valuable guidance for the rational design of advanced heterogeneous catalysts aimed at biomass valorization and the production of renewable fuel.