Selective oxidation of alcohols to aldehydes and ketones over TiO2-supported gold nanoparticles in supercritical carbon dioxide with molecular oxygen Original Research Article

Selective oxidation of alcohols to aldehydes or ketones has been investigated over nano Au catalysts using molecular oxygen in supercritical carbon dioxide (scCO2). TiO2-supported nano Au catalysts prepared by a deposition–precipitation method show unprecedented catalytic performance for selective oxidation of alcohols compared to the other Au catalysts reported so far. The results show that the selective oxidation of benzyl alcohol to benzaldehyde in scCO2 could be accomplished with a high conversion of 97% and a selectivity of 95% at 70 °C in the presence of TiO2-supported nano Au catalyst. Carbon dioxide (CO2) medium enhances the oxidation of benzyl alcohol to benzaldehyde, and inhibits the ester formation and the over-oxidation of aldehyde to the corresponding acid. The oxidation of various alcohols has also been examined and related aldehydes were obtained with good yields and selectivities.