Kinetics of chemical interesterification of sunflower oil with methyl acetate for biodiesel and triacetin production

In the present investigation, it has been determined the kinetic parameters for the chemical interesterification of sunflower oil with methyl acetate using potassium methoxide as a catalyst. Due to the presence of methanol, the possible side effects of methanolysis were also considered. The experiments were performed at 30, 40 and 50 °C and with catalyst-to-oil molar ratios of 0.1:1, 0.15:1 and 0.2:1, respectively. The first model, that considers only the kinetics of triglyceride conversion, indicated a second-order reaction and required a minimum amount of catalyst to initiate the reaction. The second theoretical model, obtained by considering the main and secondary reactions, fitted the experimental results well. It was observed that the rate of interesterification was slower than that of transesterification, with the conversion of diacetinmonoglycerides to triacetin the rate-limiting step in interesterification. Moreover, the high degree of reversibility was evidenced by the fact that the reverse reactions were more favored than the forward reactions.

► The kinetic parameters for the chemical interesterification of sunflower oil with methyl acetate using potassium methoxide as a catalyst have been determined.
► The possible side effects of methanolysis were also considered.
► The rate of interesterification was slower than that of transesterification, with the conversion of diacetinmonoglycerides to triacetin the rate-limiting step in interesterification.