Biodiesel Preparation without a Cosolvent in an Opposite-Side Micro-Fixed-Bed Reactor

Abstract

In the process of preparing biodiesel using microreactors, cosolvents and homogeneous catalysts are generally used, which adds to the separation cost. Hence, this study explored the use of an opposite-side feed micro-fixed-bed reactor with an inner diameter of 2 mm to produce biodiesel by the transesterification of soybean oil and methanol without any cosolvent, in which a fixed solid base acted as catalyst and obstacles. A biodiesel yield of 99.4% was achieved when the methanol-to-oil molar ratio was 12, the temperature was 70 °C, and the residence time was 8.05 min. A mixing study was conducted for this microreactor through computational fluid dynamics (CFD) simulations. The results showed that the best mixing index could reach 0.94 within 25 mm (length). Then, the transesterification kinetics in this reactor were found to be consistent with the proposed pseudo-homogeneous secondary reaction model. With the kinetics data and mixed-model, the biodiesel yield could be predicted. The simulated results were consistent with the experimental data.