Department of Chemical Engineering, Engineering School of Lorena, University of São Paulo, Lorena, SP, 12602-810, Brazil.
Bioprocess Biosyst Eng. 2020 Apr;43(4):615-623. doi: 10.1007/s00449-019-02257-9. Epub 2019 Nov 25.
This study investigated the synthesis of 2-ethylhexyl oleate catalyzed by Candida antarctica lipase immobilized on magnetic poly(styrene-co-divinylbenzene) particles in a continuous packed-bed bioreactor. Runs were carried out in a solvent-free system at 50 °C. The performance of the reactor was evaluated for substrates composed by oleic acid and 2-ethylhexanol at five molar ratios (1:4-4:1), determining its operation limits in terms of substrate flow rate. The system performance was quantified for three different flow rates corresponding to space-time between 3 and 12 h. For each condition, the influence of the space-time in the ester formation, esterification yield and productivity was determined. The molar ratio of acid-to-alcohol interfered, in a remarkable way, in the formation of 2-ethylhexyl oleate and the best performance was attained for substrate at equimolar ratio running at 12 h space-time. Under this condition, average 2-ethylhexyl oleate concentration was 471.65 ± 2.98 g L which corresponded to ester productivity of 23.16 ± 0.49 mmol g L h. This strategy also gave high biocatalyst operational stability, revealing a half-life time of 2063 h. A model based on the ping-pong Bi-Bi mechanism was developed to describe the kinetics of the esterification reaction and validated using experimental data. The goodness of fit of the model was satisfactory (R = 0.9310-0.9952).
本研究考察了在连续填充床生物反应器中，固定化于磁性聚苯乙烯-二乙烯基苯颗粒上的南极假丝酵母脂肪酶催化合成 2-乙基己基油酸酯。在无溶剂体系中于 50°C 进行实验。评价了该反应器在五种摩尔比（1:4-4:1）的油酸和 2-乙基己醇组成的底物下的性能，确定了其在底物流速方面的操作极限。在三个不同的时空条件下（3-12 小时），对系统性能进行了量化。对于每种条件，均确定了时空对酯形成、酯化率和产率的影响。酸醇摩尔比对 2-乙基己基油酸酯的形成有显著影响，在等摩尔比底物以 12 小时的时空运行时，表现出最佳性能。在此条件下，2-乙基己基油酸酯的平均浓度为 471.65 ± 2.98 g/L，对应的酯产率为 23.16 ± 0.49 mmol/g L h。该策略还赋予了高生物催化剂操作稳定性，半衰期为 2063 小时。建立了基于乒乓双酶机制的模型来描述酯化反应动力学，并使用实验数据对其进行了验证。模型的拟合度较好（R = 0.9310-0.9952）。
