High-performance benzyl alcohol oxidation catalyst: Au-Pd alloy with ZrO2 as promoter

Achieving the balance between the catalytic activity and product selectivity still remains a challenge in partial oxidation processes, because the products are prone to be over-oxidized. Lewis acids (such as AlCl3) have previously been identified to interact with C=O groups, which can prevent the ketone products from further transformation. In this work, ZrO2 promoted Au-Pd/gamma-Al2O3 catalyst was designed to enhance the benzaldehyde selectivity by generating more surface Lewis acid site on ZrO2-modified alumina. Results show that the introduction of ZrO2 (5%) resulted in the formation of more surface Lewis acid sites, which improved the benzaldehyde selectivity through the strengthened interaction between the Lewis acid sites and C=O groups in benzaldehyde. Besides, the addition of small amount of ZrO2 enhanced the noble metal dispersion and led to the formation of more active sites to improve the oxygen transfer during the reaction.