Supported PtSn Bimetallic Catalyst for Oxidation of 1,6-Hexanediol

A series of carbon-supported bimetallic PtSn catalysts having various Pt/Sn molar ratios was prepared and tested in the oxidation of 1,6-hexanediol with 1 MPa dioxygen at 343 K in aqueous solvent. The PtSn/C catalysts, which were initially reduced with sodium borohydride, did not produce Pt-Sn alloy particles. Instead, the catalysts were composed of SnOx moieties that were well-dispersed on the surfaces of the carbon support and the Pt nanoparticles. Subsequent treatment in H2 at 673 K induced Pt-Sn alloy formation. Whereas addition of SnOx to the Pt nanoparticles promoted the initial 1,6-hexanediol oxidation rate by 39%, the formation of Pt-Sn alloy particles decreased the initial rate. Under 1,6-hexanediol oxidation conditions, however, the Pt-Sn alloy phase separated, leading to the recovery of the catalytic activity. No significant change of product distribution was observed on bimetallic PtSn catalysts, regardless of the composition and structure.