Abstract:
Biodiesel is one of the promising alternative energy that has been studied and developed in the recent year. It consists of compounds of fatty acid alkyl ester (FAAE) mostly produced from vegetable oil and alcohol using homogeneous or heterogeneous catalyst via transesterification. However, mass transfer between two immiscible reactants and also heterogeneous catalyst are hindrance resulting in the biodiesel yield. Ultrasonic assisted reactor is a practical solution to increase the level of mixing by cavitation phenomena in fluid and carrying reactants to active site of catalyst with cavitation jet. The cavitation phenomena also produce an extremely reaction condition around 5,000°C and 1,000 atm. In this work, a study of biodiesel production from transesterification of palm oil using ultrasonic assisted reactor was investigated and compared to mechanical stirred reactor. Transesterification was operated at 60°C, 1 atm, methanol to oil molar ratio of 9:1. Sodium hydroxide homogeneous catalyst provides higher methyl ester yield and faster rate of reaction than that of calcium oxide heterogeneous catalyst. The fastest rate of reaction was achieved in ultrasonic reactor at highest catalyst loading (3%wt) and methyl ester yield increases steadily until reach the same transesterification equilibrium (about 80%). The higher ultrasonic frequency and power (50 kHz, 800 W) promoted the heterogeneously catalyzed transesterification of refined palm oil. Reusability of calcium oxide catalyzed transesterification using ultrasonic assisted reaction was also studied. It was found that calcium oxide catalyst can be used to produce biodiesel and provide high biodiesel yield for three cycles with slightly decreasing rate of reaction due to organic compounds deposition. The cognitive results from this study can be developed for the further process scale up.
