Selective hydrogenation of 5-hydroxymethylfurfural triggered by a high Lewis acidic Ni-based transition metal carbide catalyst

The high-efficiency conversion of biomass resources to biofuels has attracted widespread attention, and the active sites and synergistic effect of catalysts significantly impact their surface arrangement and electronic structure. Here, a nickel-based transition metal carbide catalyst (Ni/TMC) with high Lewis acidity was prepared by self-assembly of transition metal carbide (TMC) and nickel, which exhibited excellent performance on synergistic hydrogenation and hydrogenolysis of 5-hydroxymethylfurfural (HMF) into liquid biofuel 2,5-dimethylfuran (DMF). Notably, Ni/WC with the highest Lewis acidity (4728.3 μmol/g) can achieve 100% conversion of HMF to 97.6% yield of DMF, with a turn-over frequency of up to 46.5 h-1. The characterization results demonstrate that the rich Lewis acid sites yielded by the synergistic effect between Ni species and TMC are beneficial for the C=O hydrogenation and C-O cleavage, thereby accelerating the process of hydrodeoxygenation (HDO). Besides, a kinetic model for the HDO of HMF to DMF process has been established based on the experimental results, which elucidated a significant correlation between the measured and the predicted data (R2 > 0.97). Corresponding to the adsorption configuration of Ni/WC and substrate determined by in-situ FTIR characterization, this study provides a novel insight into the selective conversion of HMF process for functional biofuel and bio-chemicals.