Promotional synergistic effect of Sn doping into a novel bimetallic Sn-W oxides/graphene catalyst for selective oxidation of alcohols using aqueous H2O2 without additives

A series of novel catalysts with bimetallic Sn-W oxides uniformly dispersed on reduced graphene oxide (denoted as Sn-W/RGO) were successfully prepared via a conventional one-pot hydrothermal method. Interestingly, it was found that the introduction of Sn could significantly improve the catalytic activities compared with single WO3/graphene catalyst for selective oxidation of alcohols using H2O2 without organic solvents and additives. Subsequently, the catalysts were characterized by FT-IR, XRD, Raman, FESEM, EDS, HRTEM, XPS and N-2 adsorption-desorption to investigate the promotional synergistic effect of Sn among catalyst structure, surface properties and catalytic performance. The results revealed that the incorporation of Sn had induced the formation of hexagonal WO3 with dominant exposed (001) and (200) planes, meanwhile, doping Sn could dramatically increase the specific surface area, change the structural properties and enhance the interactions between Sn-W oxides and graphene, which were beneficial to the improvement of catalytic performance. Additionally, reaction parameters (temperature, time, oxidant dosage and catalyst amount) were also explored. Both aryl and alkyl alcohols exhibited high conversion and selectivity to corresponding target products over the catalyst. And delightedly, the robust catalyst could be reused for five times without significant loss in catalytic efficiency. This work demonstrates the promotional synergistic effect of Sn in a novel Sn-doped WO3/RGO catalyst and makes it a promising candidate in green oxidation of alcohols under mild reaction conditions.