脂肪酶协同催化猪油合成生物柴油工艺研究

Immobilized Lipases Cooperates to Catalyze Transesterification Reaction of Lard

探讨了以乙酸甲酯为酰基受体两种脂肪酶协同催化猪油转酯合成生物柴油的工艺条件。首先利用单因子试验确定2种固定化脂肪酶Novozym435、Lipozyme TLIM单独作为催化剂时的最佳酶用量为40%,反应温度为50℃,乙酸甲酯用量为14(相对于油的摩尔比)。在此基础上,采用3因素5水平和3个中心点的中心组分旋转设计法研究了上述2种脂肪酶协同使用时脂肪酶用量(g/g)、混合酶的配比(%/%)以及乙酸甲酯用量诸因素共同作用对转酯反应转化率的影响。优化后的反应条件为:总酶用量为40%,混合酶配比为50/50,乙酸甲酯用量为14,在该条件下甲酯得率可达97.6%,比同质量的Novozym435、Lipozyme TLIM的催化活性分别高出7.6%、22.3%。表明脂肪酶协同催化猪油合成生物柴油工艺可以较好地提高甲酯得率,并且节约生产成本。

The transesterification reaction conditions of lard with methyl acetate with combined use of immobilized lipases as catalysts were conducted. Initially, according to single factorial experiments, the studies on Lipozyme TL IM and Novozym 435 respectively catalyzed transesterification of lard showed that the optimal parameters of transesterification reaction were ： the molar ratio of methyl acetate to oil of 14 ： 1, 40% enzyme added based on oil weight, temperature 50℃. Combined use of Lipozyme TL IM and Novozym 435 was proposed further to improve the catalytic performance by the response surface method （RSM）. Herein, a 5-1evel-3-factor central composite rotated design was employed to evaluate the effects of lipase loading, the proportion of the two lipases and amount of methyl acetate. The optimum conditions were as followings： 40% lipase loading based on oil weight, 50%/50% the proportion of lipases （Novozym 435/Lipozyme TL IM）, and the molar ratio of methyl acetate to oil of 14： 1. And under the optimal conditions, the highest biodiesel yield of 97.6% could be attained, which was higher than the biodiesel yield with each single one of the two lipases. The results suggested that the technics of combined use of certain immobilized lipases catalyzed transesterification reaction of lard for biodiesel production with methyl acetate as the acyl acceptor could raise the FAME yield and save the production cost.