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

摘要

The oxidation of benzyl alcohol with 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.