Ognjanovic Nevena, Bezbradica Dejan, Knezevic-Jugovic Zorica
Faculty of Technology and Metallurgy, Department of Biochemical Engineering and Biotechnology, University of Belgrade, Karnegijeva 4, 11001 Belgrade, Serbia.
Bioresour Technol. 2009 Nov;100(21):5146-54. doi: 10.1016/j.biortech.2009.05.068. Epub 2009 Jun 21.
The feasibility of using the commercial immobilized lipase from Candida antarctica (Novozyme 435) to synthesize biodiesel from sunflower oil in a solvent-free system has been proved. Using methanol as an acyl acceptor and the response surface methodology as an optimization technique, the optimal conditions for the transesterification has been found to be: 45 degrees C, 3% of enzyme based on oil weight, 3:1 methanol to oil molar ratio and with no added water in the system. Under these conditions, >99% of oil conversion to fatty acid methyl ester (FAME) has been achieved after 50 h of reaction, but the activity of the immobilized lipase decreased markedly over the course of repeated runs. In order to improve the enzyme stability, several alternative acyl acceptors have been tested for biodiesel production under solvent-free conditions. The use of methyl acetate seems to be of great interest, resulting in high FAME yield (95.65%) and increasing the half-life of the immobilized lipase by about 20.1 times as compared to methanol. The reaction has also been verified in the industrially feasible reaction system including both a batch stirred tank reactor and a packed bed reactor. Although satisfactory performance in the batch stirred tank reactor has been achieved, the kinetics in a packed bed reactor system seems to have a slightly better profile (93.6+/-3.75% FAME yield after 8-10 h), corresponding to the volumetric productivity of 48.5 g/(dm(3) h). The packed bed reactor has operated for up to 72 h with almost no loss in productivity, implying that the proposed process and the immobilized system could provide a promising solution for the biodiesel synthesis at the industrial scale.
已证明在无溶剂体系中使用来自南极假丝酵母的商业固定化脂肪酶（诺维信435）由向日葵油合成生物柴油的可行性。以甲醇作为酰基受体，并采用响应面法作为优化技术，已发现酯交换反应的最佳条件为：45℃、基于油重量的3%酶、甲醇与油的摩尔比为3:1且体系中不加水。在这些条件下，反应50小时后，油转化为脂肪酸甲酯（FAME）的转化率>99%，但固定化脂肪酶的活性在重复运行过程中显著下降。为了提高酶的稳定性，已在无溶剂条件下测试了几种替代酰基受体用于生物柴油生产。乙酸甲酯的使用似乎很有意义，与甲醇相比，可产生高FAME产率（95.65%），并使固定化脂肪酶的半衰期增加约20.1倍。该反应也已在包括间歇搅拌釜式反应器和填充床反应器的工业可行反应体系中得到验证。虽然在间歇搅拌釜式反应器中取得了令人满意的性能，但填充床反应器系统中的动力学似乎具有稍好的曲线（8 - 10小时后FAME产率为93.6±3.75%），对应于48.5 g/(dm³·h)的体积生产率。填充床反应器已运行长达72小时，生产率几乎没有损失，这意味着所提出的工艺和固定化系统可为工业规模的生物柴油合成提供一个有前景的解决方案。
