A pilot-scale study of alkali-catalyzed sunflower oil transesterification with static mixing and with mechanical agitation

The utilization of Sulzer 15 mm SMV static mixers (SM) for the KOH-catalyzed transesterification of sunflower oil was studied by means of batch tests conducted in an experimental ring equipped with a 22 L reactor with a 6:1 methanol:oil molar ratio. The effect of SM number and superficial velocity was investigated. The results were compared to those of analogous tests performed with only mechanical agitation, at different rotational speeds and catalyst concentrations. The tests conducted with one single SM at a 1.3 m/s superficial velocity (Re = 1490) resulted in a profile of sunflower oil conversion versus time equivalent to that obtained in the best-performing test with mechanical agitation, indicating the attainment of a reaction run not affected by mass transfer limitations. In an evaluation of the energy requirement for the attainment of the alcohol/oil dispersion, the SM tests performed better than those with mechanical agitation (17 vs 35 J/kg(biodiesel), in the reaction conditions without mass transfer constraints). This analysis was scaled-up to industrial-scale biodiesel production plants, confirming the favorable performance of static mixers. On the whole, the results suggest that static mixing can be effectively applied to oil transesterification processes for biodiesel production.