OXIDATION OF LINEAR ALCOHOLS WITH HYDROGEN-PEROXIDE OVER TITANIUM SILICALITE-1

In this paper different parameters affecting the oxidation of alcohols with hydrogen peroxide are described. The influence of the amount and of the crystallite size of the catalyst, as well as the concentrations of hydrogen peroxide and substrate have been studied. The influence of the reaction temperature, the chain length of the alcohol (C6, C7, C8 and C9) and the position of the alcohol group (alpha, beta or gamma) on the reaction rate has also been investigated. As a result of this study it can be reported that the reaction is first order with respect to the amount of catalyst and the hydrogen peroxide concentration, and zero order in alcohol concentration. The activation energy for the oxidation of 2-octanol is 71 kJ/mol. The particle size has a considerable effect on the reaction rate; larger particles result slower reaction. There is a remarkable effect of the chain length on the reaction rate (C6<C7<C8 much greater than C9) and the position of the hydroxyl group has a strong effect on the activity of TS-1 (beta>alpha>gamma). The crystallite size effect can he explained by means of diffusion limitations, as could be illustrated by Weisz modulus calculations. The observed difference in activity between beta and gamma alcohols can not be related to differences in diffusion (single component diffusion of beta and gamma alcohols show little difference) and therefore transition state restrictions of the alcohols in the pores of the TS-1 may be a possible explanation for this effect.