Kinetic mechanism of transesterification of vegetable oil with supercritical methanol for Biodiesel production

The production of biofeul has recently become attractive as an alternative resource for carbon- containing fuels (fossil fuel). One of the methods to produce boifuel is the use of supercritical methanol for biodiesel production. It has recently been proven to be a successful medium for carrying out transesterification reactions. The transesterification products of vegetable oil are fatty acid ester (biodiesel) and glycerol. The most commonly used first order kinetics model has been compared with simultaneous second order kinetics model using experimental data of transesterification of rapeseed oil. The rate constants for the two models have been numerically evaluated solving ordinary nonlinear differential equations. The transesterification data characterized with 42 : 1 molar ratio of methanol to rapeseed oil were analysed for the reaction temperatures range from 270 to 380 °C under supercritical conditions. The reaction mechanism of non-catalytic transesterification of vegetable oils with supercritical methanol is explained by a series of different reaction steps to produce biodiesel. The second order kinetic model has shown the best fit to the experimental data and provided deep insight into the mechanism of the reaction.