脂肪酶催化合成生物柴油的研究

Studies of Enzymatic Synthesis of Biodiesel

生物柴油是用动植物油脂或长链脂肪酸与甲醇等低碳醇合成的脂肪酸甲酯 ,是一种替代能源。这里探讨了生物法制备生物柴油的过程 ,采用脂肪酶酯化和酯交换两条工艺路线进行催化合成。深入研究制备过程中 ,不同脂肪酶、酶的用量和纯度、有机溶剂、低碳醇的抑制作用、吸水剂的作用、反应时间和进程、底物的特异性和底物摩尔比等参数对酯化过程的影响。试验结果表明 ,采用最佳酯化反应参数和分批加入甲醇并用硅胶作脱水剂的工艺过程 ,酯化率可以达到 92 % ,经分离纯化后的产品GC分析的纯度可达 98%以上 ,固定化酶的使用半衰期可达到36 0h。同时对酯交换制备生物柴油过程中 ,甲醇的用量和甲醇的加入方式对脂肪酶催化过程的影响作了初步研究 ,优化后的酯交换率可达到 83%。

Biodiesel, an alternative diesel fuel, fatty acid alkyl ester, is made from renewable biological sources such as vegetable oils and animal fats. Two processes for biodiesel synthesis, enzymatic lipase catalytic esterification from fatty acid and transesterification from oils and fats, was investigated. The effects of various lipases, enzyme amount and purity, solvent, water absorbent, inhibition of short chains alcohol, specificity of substrate, molar ratio of substrate on esterification were studied in detail. The esterification degree with the optimal parameter and process can reach up to 92%. The purity of biodiesel obtained by separation and purification is up to 98%, and the half-life of the immobilized lipase for the esterification process can be up to 360hr, Moreover, the preliminary studies of the transesterification including the amount of methanol and mode of adding methanol into reaction system were made. The transesterification degree with adding methanol stepwise can reach 83%.