Solvent-free oxidation of benzyl alcohol using titania-supported gold-palladium catalysts: Effect of Au-Pd ratio on catalytic performance

The oxidation of benzyl alcoholwith molecular oxygen under solvent-free conditions has been investigated using a range of titania-supported Au-Pd alloy catalysts to examine the effect of the Au-Pd ratio on the conversion and selectivity. The catalysts have been compared at high reaction temperature (160 °C) as well as at 100 °C, to determine the effect on selectivity since at lower reaction temperature the range of by-products that are formed are limited. Under these conditions the 2.5 wt. Au-2.5 wt. Pd/TiO2 was found to be the most active catalyst, whereas the Au/TiO2 catalyst demonstrated the highest selectivity to benzaldehyde. Toluene, formed via either a hydrogen transfer process or an oxygen transfer process, was observed as a major by-product under these forcing conditions. © 2007 Elsevier B.V. All rights reserved.