Transesterification of vegetable oil with methanol using solid base catalyst of calcium oxide under ultrasonication

Abstract Transesterification of vegetable oil with methanol using calcium oxide as a solid base catalyst was carried out under ultrasonication and mechanical stirring conditions, and the transesterification rate was compared. In addition, the effects of ultrasonic power, catalyst mass and molar ratio of methanol to oil on methanolysis rate of oil under ultrasonication were investigated. The biodiesel yield reached 88% at about 2.5 and 5 hs under ultrasonication and mechanical stirring, respectively, thus demonstrating that ultrasonication was more effective method for the acceleration of transesterification rate. The increase in both the ultrasonic power per unit volume of mixture solution and the catalyst mass resulted in an increase in the methanolysis rate. It was found that the larger amount of methanol in an excess over the stoichiometric amount to oil played more significant role in enhancement of production rate of biodiesel in early reaction period limited by mass transfer of oil, but was less favorable for the enhancement of methanolysis rate in the reaction period limited by chemical reaction.