Continuous production of isoamyl acetate from fusel oil under supercritical CO2: A mass transfer approach

Isoamyl acetate esters were synthesized under supercritical CO2 (SC-CO2) in a continuous packed-bed reactor (PBR) using immobilized lipase (Novozym 435) as the catalyst. A fractional factorial design (24−1) was applied to evaluate the effects of pressure (10–20 MPa), temperature (40–60 °C), substrates (fusel oil + acetic anhydride) flow rate ( Q S 1 / S 2 : 0.2–0.6 mL/min), and CO2 flow rate ( Q C O 2 : 0.4–1.2 L/min) on the isoamyl acetate conversion (X, %). Results showed that only the effects of Q S 1 / S 2 were statistically significant at the level of 5%. Mathematical modeling of the PBR was applied using the law of conservation of mass that resulted in two partial differential equations for fluid and enzymes. The model was solved using finite difference methods and successfully validated with the experimental data in terms of isoamyl alcohol concentration. Finally, the model was employed to examine the impact of the input molar ratio of fusel oil per acetic anhydride (IMFA) and the length per diameter ratio (L/D) of the PBR on its performance.