Selective alcohol oxidation to aldehydes and ketones over base-promoted gold-palladium clusters as recyclable quasihomogeneous and heterogeneous metal catalysts

Bimetallic gold-palladium clusters, with an average size of 1.9 nm and composed of 80 mol% gold, proved to be highly active and selective metal catalysts for the organic phase oxidation with 02 of aliphatic, allylic and benzylic alcohols to the corresponding carbonyl products. Polyvinyl pyrrolidone stabilized gold-palladium clusters dispersed in N,N-dimethylformamide emerged as promising quasi homogeneous metal catalysts for the oxidation of benzyl alcohol to benzaldehyde with full selectivity; they could be efficiently recycled with unaffected catalytic performance by solvent-resistant nanofiltration. Highly active and durable heterogeneous catalysts for the amide phase or solvent-free alcohol oxidation were prepared by the quantitative immobilization of the optimized gold-palladium clusters on the high surface area basic BaAl2O4 spinel support with preservation of the bimetallic clusters' nanodispersion. (C) 2009 Elsevier B.V. All rights reserved.