Biosynthesized Bimetallic Au–Pd Nanoparticles Supported on TiO₂ for Solvent-Free Oxidation of Benzyl Alcohol

A green bioreductive approach with Cacumen Platycladi (<i>CP</i>) extract was adopted to fabricate bimetallic Au–Pd/TiO₂ catalysts for solvent-free oxidation of benzyl alcohol (BzOH) to benzaldehyde (BzH) with molar oxygen at atmospheric pressure. The Au–Pd nanoparticles (NPs) before being immobilized onto TiO₂ were determined by transmission electron microscopy. And, the catalysts were further analyzed by X-ray diffraction, X-ray photoelectron spectroscopy, thermogravimetric analysis, etc. Effects of Au/Pd molar ratio, preparation conditions, and reaction conditions on the catalytic activity of Au–Pd/TiO₂ were investigated. And, the Au–Pd/TiO₂ catalyst without calcination that was prepared at 90 °C from the Au–Pd NPs with Au/Pd molar ratio of 2:1 exhibited excellent catalytic performance. With the catalyst, BzOH conversion of 74.2% and selectivity to BzH 95.8% were attained at the reaction temperature of 90 °C with an oxygen flow rate of 90 mL/min. Meanwhile, the recycling tests showed that, after seven recycles, the catalyst still remained with high conversion and selectivity. Therefore, the catalyst had excellent durability and reusability and good prospects for industrial application