Liquid phase oxidation of benzyl alcohol to benzaldehyde with novel uncalcined bioreduction Au catalysts: High activity and durability

An environmentally benign bioreduction method was used to prepare Au catalysts for liquid phase oxidation of benzyl alcohol to benzaldehyde. The catalysts were characterized by N-2 physisorption, X-ray diffraction, transmission electron micrograph, thermogravimetric analysis and X-ray photoelectron spectroscopy. The performance of uncalcined bioreduction Au catalysts is evaluated with H2O2 as oxidant and without any base or organic solvent. Having investigated the effects of different reaction conditions (time, temperature, amount of catalyst and molar ratio of H2O2 to benzyl alcohol) on the catalytic performance, the optimum conditions were found to be 6 h, 80 degrees C, 0.3 g and 1.25, respectively. In terms of the catalyst parameters, gold loading of 0.3% and support Si/Ti molar ratio of 35 were demonstrated to be optimum. Under optimal conditions, benzyl alcohol conversion of 67% and benzaldehyde selectivity of 84% were achieved. Recycling tests of the catalysts manifested their durability and reusability, traits vital for industrial prospects. (C) 2012 Elsevier B.V. All rights reserved.