Transesterification of soybean oil using heterogeneous catalysts

Biodiesel is a biodegradable, nontoxic, and clean-burning fuel that can be made from biorenewable fats and oils. At present, biodiesel is primarily produced in batch reactors, where the separation of catalysts, glycerol, and biodiesel from the reactor is onerous. Solid catalysts can be used to allay this separation problem. In the present study, seven different solid catalysts (metal oxides), MgO, CaO, PbO, PbO2, Pb3O4, Tl2O3, and ZnO, with different Brunauer-Emmett-Teller (BET) surface area, acidity/basicity, and the acid/base site strength were selected for the transesterification. Biodiesel (fatty acid methyl esters, FAMEs) yields were determined for these catalysts at three different temperatures (75, 150, and 225 degrees C) and high pressure. It was observed that more than 89% yield of biodiesel was achieved with PbO and PbO2 solid catalysts.