Efficient Production of the Liquid Fuel 2,5-Dimethylfuran from 5-Hydroxymethylfurfural in the Absence of Acid Additive over Bimetallic PdAu Supported on Graphitized Carbon

A series of graphitized carbon (GC) supports with different degrees of graphitization was prepared and characterized. The study clearly showed that GC800 was the most proper support after loading the noble metal in the hydrogenation of biomass-derived 5-hydroxymethylfurfural (HMF) to liquid fuel 2,5-dimethylfuran (DMF) under mild reaction conditions. Over the Pd/GC800 catalysts, relatively high selectivity to DMF was achieved, whereas the Au/GC800 catalysts displayed extremely low selectivity to DMF. Furthermore, PdAux/GC800 (x = 1-4) catalysts with different Au/Pd mass ratios were synthesized, which showed excellent catalytic activity without any activator or acidic media. More gratifyingly, the PdAu4/GC800 catalyst gave 94.4% DMF selectivity with 86.8% HMF conversion at 150 degrees C for 4 h and maintained good stability after five cycles, which was attributed to the intimate contact and intensive interaction between the Pd and Au nanoparticles. As a result, the dispersion of particles was improved, and the content of active Pd species was increased, as evidenced in the TEM and XPS results. In addition, the influence of various reaction parameters was also investigated.