Optimization of the Epoxidation of Rapeseed Oil with Peracetic Acid

Abstract

The epoxidation of rapeseed oil (RO) with peracetic acid generated in situ by the reaction of 30 wt % hydrogen peroxide and acetic acid has been studied. The optimization studies were performed by the application of statistical experimental design methodology with the utilization of a rotatable uniform design. Four parameters for the RO epoxidation process were studied: temperature, molar ratio of hydrogen peroxide to rapeseed oil, molar ratio of acetic acid to rapeseed oil, and reaction time. The output of the process was described by five response functions: iodine number, epoxy number, conversion, yield, and the selectivity. The highest levels of all response functions, with the exception of the selectivity, were predicted for the same parameter values: temperature 65 °C, molar ratio of hydrogen peroxide to RO 11.1:1 mol/mol, molar ratio of acetic acid to RO 1.89:1 mol/mol, and the reaction time 6 h. In a confirmatory experiment, these conditions provided the epoxidized rapeseed oil with the yield of 59.3 mol %, and 83.7 mol % conversion of oil. The epoxy number of the product amounted to 0.1862 mol/100 g, whereas the iodine number was 0.0513 mol/100 g. The highest values of selectivity were predicted to require the use of different conditions: 51.5 °C, 9.7 equiv of H2O2, 0.63 equiv of AA, 6 h. These conditions gave the product with 99.2% selectivity. Epoxidized rapeseed oil is of high commercial importance as a plasticizer and stabilizer for plastics, ingredient of lubricants, polyol in manufacture of polyurethanes, and an intermediate for the synthesis of surfactants.