Characterizing the epoxidation process conditions of canola oil for reactor scale-up

Abstract

Novel epoxidized vegetable oils are of current interest for a variety of applications in coatings and polymeric materials. Samples are needed at quantities beyond gram scale to test such applications. However, scale-up of this very exothermic reaction requires an increased understanding of actual reaction temperature (Tr), which may be much higher than the water bath temperature (Tb). Canola oil (300g) was epoxidized at three H2O2 addition rates (4.6, 2.3, and 1.2gmin−1mol−1 unsaturation); at three Tb (55, 65, and 75°C); and at three reaction times (2.5, 4, and 5.5h). The addition rates were obtained by adding 180g of H2O2 over 0.5, 1, and 2h. Maximum ΔT (Tr–Tb) was attained within 30–40min of reaction time; thereafter, reactor temperatures gradually declined even though H2O2 addition continued. The maximum ΔT (8.7–15.8°C) increased as the Tb and H2O2 addition rate increased; but, no clear trend was observed in the time maximum ΔT values were attained. The ΔT vs time profile was a useful indicator of the extent of epoxidation and can be used as a criteria to stop epoxidation reaction. The greatest source of variation in oxirane content was from Tb and reaction time. Therefore, Tr must be maintained within the optimal range during the high exothermic periods, if high resin quality and minimal process time is to be achieved during scale-up.