Transesterification of canola oil to fatty acid methyl ester (FAME) in a continuous flow liquid-liquid packed bed reactor

Experiments were performed to study the mass-transfer limitations during the acid-catalyzed transesterification reaction of triglyceride (TG) with methanol (MeOH) to fatty acid methyl ester (FAME or biodiesel). The experiments were carried out as both agitated two- and single-phase reactions in an empty pipe and a packed bed reactor. The TG conversion rate increased with an increase in total superficial velocity and a decrease in packing particle diameter for the two-phase reactions. The TG conversion rate did not increase significantly with the reaction temperature for the two-phase reactions, whereas for the single-phase reactions, the TG conversion rate increased significantly as the reaction temperature increased. The rate constant at two-phase conditions (largest velocity, smallest packing particle size, and maximum pressure gradient) was comparable to that obtained at single-phase conditions, indicating that the mass-transfer limitations for two-phase experiments can be effectively overcome using a liquid-liquid packed bed reactor. The diminished mass transfer was explained by the formation of a new interfacial area between the two liquid phases, caused by the droplets being momentarily deformed into an elongated nonspherical shape as they passed through the openings between the solid particles of the packed bed.