Noble metal catalysed aerial oxidation of alcohols to aldehydes in supercritical carbon dioxide

Abstract

Platinum and palladium supported on carbons are shown to be excellent catalysts for selective oxidation of organic alcohols to aldehydes (>99%) at high yields using dioxygen as an oxidant in supercritical CO2 fluid medium. There is no detectable over-oxidation of the product to acid and no metal leaching that are commonly encountered in the conventional aqueous medium. It is also found that the hydrophobicity/hydrophilicity of the catalyst surface relative to the CO2 solvent plays a crucial role in the resulting catalytic activity and stability. Adding 1% Teflon onto the noble metal–carbon catalysts dramatically enhances the activity and lifetime of the catalysts during the aerial oxidation of fine chemicals in scCO2 fluid.