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

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.

Graphical abstractTiO2-supported nano Au (2.7 ± 0.8 nm) catalyst has been developed by a deposition–precipitation method. Our catalyst shows unprecedented catalytic performance for the oxidation of variety of alcohols with molecular oxygen in scCO2 at a low temperature of 70 °C with a good yield and a high selectivity of aldehydes.Figure optionsDownload full-size imageDownload as PowerPoint slide