(335f) Reaction Kinetics of Soybean Oil Transesterification at High Temperature
Biodiesel is a mixture of fatty acid esters which can be produced from vegetable oil or animal fats with methanol. Biodiesel is a very promising alternative fuel to traditional petroleum-based fuels, as it is nontoxic, renewable, and has better emission characteristics. Recently, there are many reports about using heterogeneously catalytic method at high temperature for biodiesel production. However, until now there is still no report about the kinetics of the heterogeneously catalytic transesterification process. In this study, the transesterification of soybean oil with methanol in the presence of zinc and lanthananium mixed oxides at high temperature was studied. The kinetic data were obtained in a perfectly mixed batch reactor. The effects of initial oil concentration (from 0.55 mol/l to 1.07 mol/l), reaction temperature (180 ? 190 oC) catalyst dosage (0.2 ? 10 wt %) and agitation speed (100 ? 600 rpm) were investigated over a low oil conversion range (0 ? 15 %). A kinetic model was developed based on a three-step ?Eley?Rideal' type of mechanism applied in liquid phase. The reaction was found to be a first-order kinetic law. The temperature effect on the kinetic constants was determined by fitting the data to the Arrhenius equation. The energy of activation was 91.28 KJ/mol-1, which was a little lower than NaOH-catalyzed process.