Yield and the Reaction Kinetics of Transesterification of Soybean Oil Using Solid Catalysts

Abstract

Homogeneous acid or base catalysts dissolve fully in the glycerol layer and partially in the fatty acid methyl esters (biodiesel) layer in the triglyceride transesterification process. Heterogeneous (solid) catalysts, on the other hand, can prevent catalyst contamination making product separation much simpler. In the present work, five different solid catalysts were used in a transesterification reaction with soybean oil. We found that heterogeneous catalysts require much higher temperatures and pressure to achieve acceptable conversion levels when compared to using homogeneous catalysts. Subsequent to preliminary investigations, transesterification was conducted for selected high performance solid catalysts, i.e., MgO, CaO, BaO, PbO, and MnO2 in a high pressure reactor up to a temperature of 215 0C. The yield of the fatty acid methyl esters and the kinetics (rate constant and order) of the reaction were estimated and compared for each catalyst.