Transesterification for the preparation of biodiesel from crude-oil of Pongamia pinnata

Abstract

Biodiesel was prepared from the non-edible oil of Pongamia pinnata L. by transesterification of the crude-oil with methanol in the presence of NAOH as catalyst. Vegetable oils can be transesterified by heating them with a large excess of anhydrous methanol and an acidic or basic reagent as catalyst. Both the acid as well as alkaline esterifications were subsequently performed to get the final product. A catalyst is usually used to improve the reaction rate and yield. NaOH was found to be a better catalyst than KOH in terms of yield. In a transesterification reaction, a larger amount of methanol was used to shift the reaction equilibrium to the right side and produce more methyl esters as the proposed product. Several aspects including the type of catalyst (alkaline, acid, or enzyme), alcohol/vegetable oil molar ratio, temperature, purity of the reactants (mainly water content) and free fatty acid content have an influence on the course of the transesterification. A maximum conversion of 94% (oil to ester) was achieved using a 1:10 molar ratio of oil to methanol at 60 to 65 ?C. Important fuel properties of methyl esters of pongamia oil (biodiesel) compare well with ASTM standards.