Immobilized lipase-mediated long-chain fatty acid esterification in dense carbon dioxide: bench-scale packed-bed reactor study

Abstract

Long-chain fatty acid esters are useful functional molecules responding to the requirements of numerous fields of application in cosmetic, pharmaceutical and lubricant industry. In the present work, lipase-catalysed production of n-octyl oleate by esterification of oleic acid with 1-octanol in dense CO 2, as reaction medium, was performed in bench-scale packed-bed bioreactor, in order to obtain suitable reaction performance data for up-scaling. Lipase from Rhizomucor miehei (Lipozyme RM IM) was used as the biocatalyst. The experiments were planned to elucidate the effect of several process parameters, such as pressure, temperature, CO 2 and substrates flow rates. Pressure of 10 MPa, temperature of 323.15 K, CO 2 flow rate of 210 dm 3/h and substrates flow rate of 18 cm 3/h were predicted to be the optimum conditions: a maximum yield of about 93% was attained. Performing the enzymatic reaction in the continuously operating bioreactor, a long-term enzyme lifetime was observed and a decrease of the Lipozyme activity was not registered over 50 days. A comparison with experimental results obtained in batch-wise was also proposed. Operating at the optimum reaction conditions, higher ester yield than those obtained in batch-mode was detected. Supercritical carbon dioxide (SC-CO 2) showed to be a potential medium for the n-octyl oleate biosynthesis for a large-scale production in continuous-mode.