Kinetics of heterogeneous oxidation of benzyl alcohol with hydrogen peroxide

A clean catalytic process for the synthesis of benzaldehyde (BzH), with high selectivity, from benzyl alcohol (BzOH) by oxidation with hydrogen peroxide (H2O2), without any organic solvent in a batch reactor is studied. Oxidation of BzOH to BzH was carried out at different speeds of agitation (800-1500 rpm), temperatures (343-363 K), catalyst loadings ((3.4-5.9) x 10(-3) mol/L) and mole ratios of BzOH:H2O2 (1:1-1:2). Effect of various catalysts, e.g. tungstic acid, ammonium molybdate, and sodium tungstate and sodium molybdate on the oxidation of BzOH to BzH was studied. Ammonium molybdate was found to be the best catalyst for the oxidation of BzOH as compared to other catalysts. Increasing the speed of agitation beyond 1000 rpm has no significant effect on the rate of the oxidation of BzOH, indicating the absence of mass transfer resistance. Kinetics of the reaction have been established and values of activation energy have been reported. (C) 2004 Elsevier B.V. All rights reserved.