Kinetics of transesterification in rapeseed oil to biodiesel fuel as treated in supercritical methanol

A kinetic study in free catalyst transesterification of rapeseed oil was made in subcritical and supercritical methanol under different reaction conditions of temperatures and reaction times. Runs were made in a bath-type reaction vessel ranging from 200°C in subcritical temperature to 500°C at supercritical state with different molar ratios of methanol to rapeseed oil to determine rate constants by employing a simple method. As a result, the conversion rate of rapeseed oil to its methyl esters was found to increase dramatically in the supercritical state, and reaction temperature of 350°C was considered as the best condition, with the molar ratio of methanol in rapeseed oil being 42.