Bimetallic Gold–Palladium vapour derived catalysts: The role of structural features on their catalytic activity

A procedure to synthesize new Au–Pd bimetallic catalysts using Au and Pd vapours as reagents (metal vapour synthesis, MVS) is reported. The simultaneous co-condensation of Au and Pd vapours with acetone vapour affords Au–Pd/acetone-solvated metal atoms which have been used to deposit Au–Pd bimetallic nanoparticles on γ-alumina and titanium oxide supports. Transmission electron microscopy (TEM) analysis determined the nanoparticles dimensions (dm = 2.2–2.4 nm) and size distribution while the X-ray absorption spectroscopy (XAS) analysis showed the presence of small bimetallic Au–Pd nanoparticles with a large amount of Au–Pd bonds. The bimetallic co-condensed systems, tested in the selective oxidation of benzyl alcohol with molecular oxygen both in toluene solvent and in solvent-free conditions, showed higher catalytic activity and selectivity than the corresponding monometallic systems as well as of the analogous systems obtained by separate evaporation of the two metals.