Continuous Enzymatic Synthesis of 2-Ethylhexyl Oleate in a Fluidized Bed Reactor: Operating Conditions, Hydrodynamics, and Mathematical Modeling

The continuous synthesis of 2-ethylhexyl oleate catalyzed by Candida antarctica lipase immobilized on magnetic poly(styrene- co -divinylbenzene) particles was performed in a solvent-free fluidized bed reactor (FBR). The effects of space time (6, 12, and 18 h) and bed porosity (0.866, 0.892, and 0.916) were investigated to determine the best operating conditions. Experimental results showed that high ester productivity (0.73 mmol g –1 h –1 ) and a satisfactory esterification yield (48.24%) were achieved at a space time of 12 h and a bed porosity of 0.892. It was also observed that the higher the bed porosity, the higher the mass transfer coefficient and, consequently, the reactor productivity. This finding can be explained by the high interstitial velocity of the fluidized bed bioreactor, which increases the mixing degree and improves mass transfer. A mathematical model accounting for internal and external particle transfer effects was proposed based on ping-pong bi–bi enzyme kinetics. The FBR was described in a simplified manner, considering an agitated tank reactor, a strategy that provided good correlation ( R 2 = 0.991) between experimental and model results. Immobilized lipase showed high operational stability (half-life of 1716 h) qualifying as a promising biocatalyst for industrial-scale applications.