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

The oxidation of benzyl alcohol with molecular oxygen under solvent-free conditions has been investigated using a range of titanic-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 degrees C) as well as at 100 degrees 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. (C) 2007 Elsevier B.V. All rights reserved.