Carbon-coated CuCo catalyst with altered adsorption mode for efficient transfer hydrogenation of 5-hydroxymethylfurfural to 2,5-dimethylfuran using ethanol as hydrogen donor

The transfer hydrogenation of 5-hydroxymethylfurfural (HMF) to 2,5-dimethylfuran (DMF) using ethanol as the hydrogen donor represents a green and efficient route for biomass valorization. In this work, a carbon-coated CuCo catalyst was designed to catalyze this transformation, achieving a high DMF yield of 96.4 % at 180°C within 6 h. Isotopic labeling indicated that transfer hydrogenation proceeded via a metal-mediated mechanism, while combined experimental and theoretical observations revealed that the formation of CuCo alloy optimized the adsorption modes of HMF. Specifically, the adsorption of the aldehyde group in HMF changed from η 1 to di-σ C,O configuration, weakening the C=O bond and thus facilitating hydrodeoxygenation. Notably, the CuCo alloy weakened the adsorption strength of HMF on the catalyst surface, preventing competitive adsorption from inhibiting ethanol dehydrogenation. These optimized adsorption interactions ensured the smooth progress of ethanol dehydrogenation and HMF hydrogenation, enabling CuCo catalyst to exhibit excellent performance in the transfer hydrogenation reaction.