Optimization of biodiesel production from soybean oil in a microreactor

• Continuous transesterification of soybean oil is studied in a microreactor.
• Box–Behnken method and response surface methodology used for optimization.
• Fatty Acid Methyl Ester transesterification of 89% obtained at optimum condition.
• The microchannel pressure drop was related to energy dissipation rate and FAME %.
• Higher FAME % values were obtained at higher energy dissipation rate.

Transesterification of soybean oil with methanol in the presence of potassium hydroxide, as a catalyst, in a microreactor has been investigated. The transesterification reaction was performed at specific condition in circular tubes with hydraulic diameter of (0.8 mm). In order to further improve the biodiesel production, the experimental design was performed using Box–Behnken method. The results were analyzed using response surface methodology. The influence of reaction variables including; molar ratio of methanol to oil (6:1–12:1), temperature (55–65 °C) and catalyst concentration (0.6–1.8 wt.%) and residence time (20–180 s) under various flow rates of reactants (1–11 ml min−1) on Fatty Acid Methyl Ester (FAME) transesterification reaction was studied. The optimum condition was found at molar ratio of methanol to oil (9:1), catalyst concentration (1.2 wt.%) and temperature (60 °C) with a FAME % of about 89%. Considering optimum parameters, by changing the reactant residence time the FAME % was reached to 98% at 180 s.

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