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Continuous alkali-catalyzed transesterification of rapeseed oil with methanol was carried out in three mesoreactor designs. The induction time decreased with oscillatory Reynolds number for all three reactors. Stable steady states were achieved within induction times of 1.5, 2.5, and 4.0 residence times for the integral, wire wool, and helical baffle designs, respectively. Both experimental and simulated results indicated that under the given conditions there is an optimal residence time for homogeneous transesterification. Higher residence times resulted in reduced fatty acid methyl ester content due to the saponification side reaction. The results demonstrate that biodiesel can be produced at an industrially acceptable level of conversion (> 95 %) in < 5 min residence time. This requires a combination of high catalyst concentration and good mixing.

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A more robust kinetic model of base-catalysed transesterification than the conventional reaction scheme has been developed. All the relevant reactions in the base-catalysed transesterification of rapeseed oil (RSO) to fatty acid methyl ester (FAME) were investigated experimentally, and validated numerically in a model implemented using MATLAB. It was found that including the saponification of RSO and FAME side reactions and hydroxide-methoxide equilibrium data explained various effects that are not captured by simpler conventional models. Both the experiment and modelling showed that the "biodiesel reaction" can reach the desired level of conversion (>95%) in less than 2min. Given the right set of conditions, the transesterification can reach over 95% conversion, before the saponification losses become significant. This means that the reaction must be performed in a reactor exhibiting good mixing and good control of residence time, and the reaction mixture must be quenched rapidly as it leaves the reactor.

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