Improvements in the Modeling and Kinetics Processes of the Enzymatic Synthesis of Pentyl Acetate

In this work, the enzymatic synthesis of pentyl acetate obtained from acetic acid and pentan-1-ol using the commercial immobilized lipase Lipozyme (R) 435 was studied. Specifically, the effects of several variables of the process on the kinetics were shown, such as the initial concentration of the acetic acid, the alcohol/acid molar ratio, and the possible reuse of the enzyme, while other variables, such as temperature, agitation, and the enzyme/acid ratio were held constant. The kinetics were determined by assessing the acetic acid concentration throughout the reactive process. Experimental data were correlated with the rate equation consisting of a modified version of the Bi-Bi Ping-Pong mechanism. The results showed that when no hydrophobic solvents were used with the reagents in stoichiometric proportion, a high molar fraction of acetic acid (x(0,acid) approximate to 0.50) caused the loss of enzymatic activity, achieving a conversion of only 5%. However, when there was an excess of pentan-1-ol, the reaction occurred successfully. Under optimal conditions (solvent-free conditions, x(0,alcohol)/x(0,acid) = 2, and x(0,acid) = 0.33), it was found that the enzyme could be reused up to 10 times without a loss of activity, reaching conversions higher than 80% after 8 h. Therefore, those conditions are advantageous in terms of productivity.