凯发

Pt nanocatalysts loaded on reduced graphene oxide (Pt/RGO) were prepared via a convenient microwave-assisted reduction approach with ethylene glycol as reductant. The conversion of cellulose or cellobiose into sorbitol was used as application reaction to investigate the catalytic performance of Pt/RGO catalysts. Carbon materials including activated carbon, graphite oxide, reduced graphene oxide (RGO), carbon nanotubes and graphene were compared, being directly used as catalysts to obtain sorbitol from cellobiose. The results showed that the catalytic activities of graphite oxide, carbon nanotubes and RGO were better than those of above mentioned other carbon catalysts, which was attributed to the unique graphene sheet structure and rich functional groups. Furthermore, various metal nanocatalysts loaded on RGO were prepared by the same reduction method and their catalytic performances were compared. Pt loaded on RGO exhibited the highest catalytic activity with 91.5% of sorbitol yield from cellobiose. Finally, the catalytic performances on the conversion of cellulose or cellobiose to sorbitol were compared as well on Pt nanocatalysts supported on different carbon materials or on silica support. The result showed that RGO was the best catalyst support, and the yield of sorbitol was as high as 91.5% from cellobiose and 58.9% from cellulose, respectively. The improvement of catalytic activity was attributed to the appropriate Pt particle size and hydrogen spillover effect of Pt/RGO catalyst. Interestingly, the size and dispersion of supported Pt particle could be easily regulated by convenient adjustment of the microwave heating temperature. The catalytic performance was found firstly increased and then decreased with increasing particle size. The optimum Pt particle size was 3.6 nm. These findings may offer useful guidelines to design novel catalysts with beneficial catalytic performance for biomass conversion, and to understand the hydrogen spillover effect of graphene/graphene oxide based catalysts.