Perspectives on the kinetics of diol oxidation over supported platinum catalysts in aqueous solution

The catalytic oxidation of a variety of terminal alcohols was performed over Pt/C with 10 bar dioxygen at 343 K in aqueous solvent at low pH. The influences of Pt particle size, carbon support, alcohol structure, and start-up conditions were explored. Although the turnover frequency was not affected by particle size or the carbon support, the structure of the alcohols affected their initial rate of conversion. Both the rate of oxidation of α,ω-diols and selectivity of the diols to the diacids increased with increasing carbon chain length. The rate of 1,6-hexanediol oxidation was independent of dioxygen pressure and the order of reaction with respect to diol concentration depended on the start-up conditions. A kinetic model involving two types of metal sites was proposed to account for the experimental observations.