Biodiesel Fuel Production from Soybean Oil Using a Microreactor

The synthesis of fatty acid methyl ester from soybean oil was examined. A microreactor was used as a reactor, and the results were compared with those by batch reaction. In a batch reaction experiment, the concentration of by-product glycerol was large when methanol/soybean oil ratio was low, which inhibited the mass transfer between methanol and oil, and as a result, reduced fatty acid methyl ester yield. On the other hand, when the reaction was conducted under an emulsion state using a microreactor, the initial reaction rate was significantly increased, achieving a specific interfacial area about 7 times larger than that of the batch reaction. Furthermore, the decrease in reaction rate was suppressed and the space-time fatty acid methyl ester yield was successfully increased. When the reaction was conducted under a segmented flow state, the initial reaction rate decreased because of the smaller specific interfacial area. However, the mass transfer coefficient increased about 30-fold, and furthermore, the phase separation was completed immediately after the reaction. Finally, the high temperature and high-pressure flow operation was conducted using a microreactor, which enabled an efficient fatty acid methyl ester production from soybean oil at 2 - 3 times higher space-time yield with less amount of catalyst and/or methanol use compared to the conventional batch production method.