Selective Aerobic Oxidation of Alcohols over Gold-Palladium Alloy Catalysts Using Air at Atmospheric Pressure in Water

Graphical Alloys of Catalysis ! Synergistic effect in Au−Pd alloy catalysts enhanced selective aerobic oxidation of alcohols using air at atmospheric pressure in water. A series of bimetallic Au−Pd alloy nanoparticles (NPs) with varied Au/Pd molar ratios was supported on Gamma-alumina (γ-Al 2 O 3 ) surface through the co-impregnation-reduction method using HAuCl 4 and PdCl 2 as metal precursors. Characterization results suggested the high dispersion of Au−Pd alloy NPs, as well as the interplay between the two compositions. Benefitting from the synergistic effects of Au−Pd alloying, the bimetallic Au-Pd x @γ-Al 2 O 3 catalysts were highly efficient for selective aerobic oxidation of various alcohols either aromatic or aliphatic in water using air at atmospheric pressure as a sole oxidant without the need for any cocatalyst. Quantitative yields of corresponding aldehydes or ketones were achieved over Au-Pd 1.2 @γ-Al 2 O 3 within 2 h, whereas pure Au@γ-Al 2 O 3 or Pd@γ-Al 2 O 3 was far less efficient. More importantly, the “alloying effect” appeared to stabilize the bimetallic NPs against aggregation and poisoning, which made the Au-Pd x @γ-Al 2 O 3 more stable and reusable in the aerobic oxidation of alcohols.