Optimization of epoxidation of ricinoleic acid methyl ester by hydrogen peroxide and phase-transfer catalyst using response surface methodology

摘要

The epoxidation of ricinoleic acid methyl ester (RAME) has been investigated using an environmentally friendly oxidant (i.e., hydrogen peroxide) and a phase-transfer catalyst ([-C5H5N(CH2)(15)CH3](3)[PW4O16]) in dichloroethane. The response surface methodology (RSM), based on the Box-Behnken design was used to assess individual and interactive effects of the process variables and to optimize the epoxidation reaction condition. The coefficient of determination (R-2=0.9544) obtained from analysis of the variance confirmed the suitability of the fitted model. The RSM analysis results indicated that the molar ratio of H2O2 to CC bonds and the reaction temperature are the most significant (P0.01) factors affecting the conversion of RAME epoxide. In addition, the interaction between the H2O2/CC molar ratio and the catalyst dosage also has significant effect (P0.05) on the conversion of RAME epoxide. The optimum reaction conditions for the epoxidation of RAME were H2O2: CC molar ratio of 1.93:1, catalyst dosage of 3.11wt% (substrate:catalyst molar ratio=207), reaction temperature of 52 degrees C, and reaction time of 75min, under which a conversion of 94.52% could be achieved. The epoxidation of RAME by hydrogen peroxide and the (-C5H5N[CH2](15)CH3)(3)(PW4O16) phase-transfer catalyst followed pseudo-first order kinetics with an activation energy (E-a) of approximately 21.6kJ/mol. The reaction process is a mass-transfer control process.