Selectivity of Gold Catalysts for Selective Hydrogenation of Cinnamaldehyde

Gold nanoparticles (AuNPs), SiO2 and TiO2 supported AuNPs prepared by colloid deposition method and Au/TiO2 prepared by deposition-precipitation method (Au/TiO2-DP) were used for the liquid-phase selective hydrogenation of cinnamaldehyde. The catalysts were characterized by HRTEM, H-2-TPR and XPS. Results showed that AuNPs, AuNPs/SiO2 and AuNPs/TiO2 in dried form selectively hydrogenated the C=C bond, whereas AuNPs/TiO2 treated in H-2 and Au/TiO2-DP preferentially hydrogenated the conjugated C=O bond. From our data, high selectivity toward cinnamyl acohol could be mainly attributed to an electron transfer from the reduced support to gold, which creates more electron-enriched gold particles, favouring C=O hydrogenation.