Restructuring of supported PtSn bimetallic catalysts during aqueous phase oxidation of 1,6-hexanediol

Abstract

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 1MPa dioxygen at 343K 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 673K 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.