Epoxidation Of Fatty Acid Methyl Ester By Hydrodynamic Cavitation

Epoxy fatty acid methyl ester (FAME) was considered as a new kind of plasticizer and widely used in polyvinyl chloride (PVC) industry, due to its innocuity, good compatibility, biodegradation and renewability. Epoxy FAME could be prepared by epoxidation of FAME, which is produced from waste cooking oil. On an industrial scale, there were some problems in epoxidation process of FAME:long reaction time, poor production quality, high energy consumption and equipment corrosion. In order to solve above problems, a new method to prepare epoxy FAME was developed by utilizing hydrodynamic cavitation in formic acid autocatalytic system. The main content as well as the achieved conclusions is as follows:(1) The epoxidation experiments of FAME using formic acid autocatalytic system were conducted in hydrodynamic cavitation circulation reactor, meantime, the mixing effect between hydrodynamic cavitation and typical mechanical stirring method was compared. Effects of epoxidation steps, circulation rate, volume ratio of organic phase to aqueous phase in circulating stream and inlet pressure of orifice plate on the epoxidation of FAME were investigated, respectively. Result showed that the mixing effect and reaction rate of hydrodynamic cavitation were better than those of mechanical stirring method In comparison with one step of epoxidation, the epoxidation process with two steps was preferred under the same feeding amount of raw material, and the reaction time decreased significantly. The optimum op parameters in hydrodynamic cavitation circulation reactor such as circulation rate, volume ratio of organic phase to aqueous phase in circulating stream and inlet pressure of orifice plate were 0.6 L/min,1:1 and 0.4 MPa, respectively. Under the optimum operating condition, the corresponding oxirane content value, iodine value of product, conversion ratio and selectivity were found to be 4.45%,3.9 g/100 g, 95.7%,78.8%, respectively.(2) FLUENT software was used to simulate the flow field of hydrodynamic cavitation circulation reactor. Effect of circulation rate on the distribution of two phases was investigated. Result showed that circulation rate directly influenced the mixing effect of two phases. At 0.6 L/min of circulation rate, the distribution ratio of two phases approached to 1:1, which was beneficial to reaction and consistent with the experimental results.(3) In formic acid autocatalytic system, the kinetics for the epoxidation of FAME was studied in glass stirring reactor. Results showed that the epoxidation reaction orders for each reactant were found to be 1.43 orders with respect to double bonds of FAME concentration and 1 order to the formic acid concentration, respectively, the corresponding activation energy for epoxidation was 56.3 kJ/mol. The reason of the oxirane ring cleavage was mainly attributed to the attack of formic acid, not by water. The oxirane ring cleavage reaction orders by formic acid were found to be 1 order with respect to epoxy FAME concentration and 1.85 orders to the formic acid concentration, respectively, the corresponding activation energy for oxirane ring cleavage was 94.7 kJ/mol.