Multi-stage Microwave-assisted Transesterification of Soybean Oil – An Economic Design for High Yield Biodiesel Production

Abstract

A multi-stage microwave-assisted transesterification apparatus for biodiesel production is designed by connecting a microwave to a low-pressure reactor to form a flow-through microwave's circulation reaction system. After each stage of reaction, the mixture is centrifuged to expel glycerol phase and transferred to the reactor for subsequent reaction stages, namely Stage II to V. Refilling tests of different reactants are operated with four conditions (Condition A-D). Among these conditions, Condition B, C and D can produce high FAME yield (100%) since Stage II. With persistent refilling of reactants, as Condition C, the reactions can be performed for at least five stages with a steady SBO amounts (approximately 0.1 mole) and low surplus rates of oil (5 to 8%). The reaction time can be shortened to 6 minutes, with 3 minutes' intermittent microwave irradiation. This study has demonstrated that multi-stage microwave-assisted transesterification is effective, feasible, and affordable for scale-up biodiesel production