Development of an immobilized enzyme-catalyzed biodiesel producing process from fats and oils

对催化米糠油甘油三酯(TG)与碳酸二甲酯(DMC)反应生成脂肪酸甲酯(BDF)的脂肪酶进行了筛选。洋葱伯克霍尔德氏菌(BCL)和产碱杆菌脂肪酶在18种脂肪酶中(PL和QLm)活性较高。以天然QLM脂肪酶为原料，采用交联酶聚集体(CLEAS)法和Accurel MP-1000物理吸附法制备了固定化酶。用丙酮或1，2-二甲氧基乙烷从缓冲溶液中沉淀QLm，或在二苯并-18-冠-6共存下与二甲醚沉淀QLm，然后用戊二醛进行交联，吸附在Accurel上的QLm的活性高于天然QLm(粉末状)，24 h后BDF得率已达到90%。以Accurel固定化QLM的半衰期表示的操作稳定性长期稳定到30000 h(418个运行周期，1270天，3.5年)。反应后蒸馏剩余的DMC分离出的下甘油相不是游离甘油，而是甘油DMC的衍生物。总而言之，当酶的成本被搁置一边时，能够找到二氧化碳排放最少的脂肪和油生产BDF的过程。

The lipase which catalyze the reaction of rice-bran oil triglycerides (TG) and dimethyl carbonate (DMC) to afford fatty acid methyl ester (BDF) was screened. Lipases from Burkholdelia cepacia (BCL) and Alcaligenes sp. (PL and QLM) were high active in 18 kinds of lipase. Immobilized enzyme was prepared employing native QLM lipase by the crosslinked enzymes aggregates (CLEAs) method and the physical adsorption method of Accurel MP-1000 of porous polypropylene powder. The precipitated QLM with acetone or 1, 2-dimethoxyethane (DME) from aqueous buffer solution, or that with DME under the coexistence of dibenzo-18-crown-6 followed by the crosslinking with glutaraldehyde, and the QLM adsorbed in Accurel were high active than native QLM(powdery); the yield of BDF was already quantitative (90%) after 24 h. The run for one batch reaction (TG 2.0 mmol, DMC 35.7 mmol, 50℃, 72h) was repeated with the fresh substrate with the same immobilized QLM or native QLM, and the tolerance of the repetition response were investigated. The operational stability expressed in terms of the half-life for the Accurel immobilized QLM was as stable as 30,000 h (a 418 Run cycles, 1270 days, 3.5 years) over a long-term. The lower glycerin phase that separated out by distilling the excess DMC after the reaction was not free glycerin but glycerin DMC derivatives. As general overviews, when the cost of the enzyme was set a aside, the BDF producing-process from fats and oils with least carbon dioxide emission was able to be found out.