Liquid-Phase Oxidation of Alcohols Catalyzed by ZrO2 under Solvent Free Conditions

The selective oxidation of alcohols, in an environmental friendly protocol, was carried out under solvent free conditions using molecular oxygen as the oxidant and ZrO2 as the catalyst. Benzaldehyde, cyclohexanone, and octanal were the major products from their respective alcohols. The influence of different reaction parameters (speed of agitation, reaction time, and temperature), catalyst parameters (calcination temperature and loading), and oxygen partial pressure on the catalyst performance was studied. ZrO2 calcined at 1223 K was found to be more active than the one calcined at 723 K for alcohol oxidation to the corresponding carbonyl products. The catalyst is insoluble in the reaction mixture and can be easily separated by simple filtration and reused. The agitation speed beyond 900 r/min showed no significant effect on the rate of conversion.