Kinetics of Canola Oil Transesterification in a Membrane Reactor

Biodiesel is quickly gaining attention as a renewable and environmentally friendly replacement for petroleum-based diesel. The dominant process involved in its production is transesterification consisting of three consecutive reversible reactions. For this work, the transesterification of canola oil was conducted using a continuous membrane reactor in the presence of NaOH as a catalyst. The forward and reverse rate constants of all three steps involved in the transesterification in the membrane reactor are reported. The proposed mathematical model fitted the experimental results well. It was found that increasing the catalyst concentration increased the reaction rates and the residence time did not have a significant influence on the reaction rates. Runs were performed at 0.05, 0.1, and 0.5 wt % NaOH based on the oil. A mole ratio of 24:1 methanol/oil was used in this work. The forward rate constants were greater than previously reported for a batch process. This was attributed to the excellent mixing in the membrane reactor loop, the higher methanol/oil mole ratio used here, and the continuous removal of product from the reaction medium. The advantages of using a membrane rector to enhance the reaction rate in the transesterification of canola oil in a membrane reactor were clearly shown.