Catalytic hydrodeoxygenation of 5-hydroxymethylfurfural to 2,5-dimethylfuran over Pd-Co bimetallic catalysts supported on MoC_x

Dimethylfuran is a promising liquid fuel that can be derived from sustainable biomass sources. Obtaining dimethylfuran from biomass through an efficient catalytic hydrodeoxygenation process is an effective way to achieve carbon neutrality. Herein, we report a catalytic system employing a highly dispersed Pd-Co bimetallic catalyst supported on molybdenum carbide for the conversion of 5-hydroxymethylfurfural to dimethylfuran. Bimetallic catalysts with varying Co loading were prepared via co-precipitation and temperature-programmed carburization, followed by a series of hydrodeoxygenation performance evaluation. The results reveal that, at 180 °C and 2 MPa hydrogen pressure, the 0.5Pd10Co/MoC_x catalyst achieves a remarkable 5-hydroxymethylfurfural conversion of 99.9 % with a dimethylfuran selectivity exceeding 97 %. Comprehensive characterizations confirm the role of bimetallic active sites and suggest the reaction mechanism. Pd doping enhances the surface area and promotes hydrogen dissociation, and consequently lowering the reduction temperature of catalyst. The unique electronic structure of Mo in the carbide support promotes charge transfer from the support to the Pd-Co bimetallic site, thereby promoting the generation of more Co^δ+ and Co²⁺. The presence of a high oxygen vacancy content facilitates the cleavage of C-O bonds, while the synergy effect of bimetallic sites changes the reaction path and promotes the hydrogenation of the aldehyde group, thus greatly improving the reaction efficiency.