Epoxidation of vegetable oils in a semibatch reactor: From reaction kinetics to reactor modelling

Epoxidized vegetable oils are used as green intermediates in organic synthesis as well as biolubricants and plasticizers. Epoxidation of double bonds in a commercial vegetable oil mixture was carried out in a laboratory-scale semibatch reactor, which was operated at 25-30 o C and at atmospheric pressure. Potassium persulphate was used as the oxidation agent and potassium hydroxide was added to the reaction mixture to maintain the pH constant. An extensive experimental optimization of the reaction conditions (oxidant-to-double bond ratio and oxidant feed rate) was carried out, revealing that more than 95% of the double bonds could be epoxidized in the best cases. The experiments provided a large set of kinetic data which were modelled mathematically. Mathematical expressions for the epoxidation rate were derived, based on plausible reaction mechanisms and on the principle of quasi-stationarity for the reaction intermediates appearing in the molecular mechanism of the double bond epoxidation. The kinetic parameters in the mathematical model, a set of ordinary differential equations for the components in the semibatch reactor, were determined by non-linear regression analysis. A comparison of the model predictions with experimental data revealed that the model described the epoxidation kinetics of vegetable oils in the isothermal and isobaric semibatch reactor very well. • Epoxidation of commercial vegetable oil was successfully carried out in semibatch reactor. • Potassium persulphate was used as oxidation agent. • Extensive experimental optimization of the reaction conditions was carried out. • Detailed kinetic modelling of the experimental data was performed. • The model described the epoxidation kinetics very well.