Catalytic in-situ hydrogenation of 5-hydroxymethylfurfural to 2,5-dimethylfuran over Cu-based catalysts with methanol as a hydrogen donor

A series of Cu-based catalysts with different supports were synthesized and studied for the in situ hydrogenation of 5-hydroxymethylfurfural (5-HMF) to dimethylfuran (DMF) using methanol as an economical hydrogen donor. The structures and properties of the four catalysts (Cu/Al₂O₃, Cu/ZnO, Cu/ZrO₂, and Cu/CeO₂) were characterized using X-ray diffraction (XRD), temperature-programmed reduction (H₂-TPR), and temperature-programmed desorption of ammonia (NH₃-TPD). The experimental results showed that the use of different supports for the Cu-based catalysts significantly influenced their activity for both H₂ production from methanol and hydrogenation of 5-HMF. The catalyst Cu/Al₂O₃ showed the best catalytic activity, which can be attributed to the highest activity for the in situ H₂ production from methanol, smallest Cu crystallite size, and strongest acidity. The effects of the substrate concentration, catalyst loading, and reaction temperature and time on the in situ hydrogenation of 5-HMF were systematically investigated to determine the optimum reaction conditions.