微乳体系中脂肪酶催化棕榈酸制备生物柴油及其工艺优化

摘要

Biodiesel was prepared via esterification of palmitate acid and ethanol in the dodecyl benzenesulfonic acid (DBSA) + TX-100/cyclohexane/1-Butyl-3-methylimidazolium tetrafluoro-borate (BmimBF4) microemulsion system with Candida rugosa lipase as catalyst.The effects of several parameters such as the amount of ionic liquid,molar ratio of reactants,the amount of lipase,reaction temperature and reaction time on the yield of ethyl palmitate were investigated.On the basis of the single factor experiments,the preparation process of biodiesel was optimized by response surface methodology (RSM) based on the principle of experimental design of Box-Behnken (BBD).Accordingly,a maximum ethyl palmitate yield of 97.5％ was obtained under the optimal condition:amount of ionic liquid BmimBF4 is 30％,ethanol/acid molar ratio of 6.3∶ 1,the amount of lipase to palmitate acid is 14％,reaction temperature is 34 ℃ and reaction time is 3.0 h.These results basically comformed to the predicted value by a mathematical model.%以十二烷基苯磺酸(Dodecyl benzenesulfonic acid,DBSA) +TX-100/环己烷/1-丁基-3-甲基咪唑四氟硼酸盐(BmimBF4)微乳体系为反应介质,Candida rugosa脂肪酶为催化剂,进行棕榈酸与乙醇酯化反应制备生物柴油,并考察离子液体用量、醇酸摩尔比、脂肪酶用量、反应温度、反应时间等因素对棕榈酸乙酯产率的影响.在单因素实验的基础上,根据中心组合Box-Benhnken实验设计原理,采用响应面分析法对生物柴油制备工艺进行优化.结果表明生物柴油制备的最佳工艺条件为:离子液体BmimBF4用量30％,醇酸摩尔比6.3∶1,脂肪酶用量为棕榈酸质量的14％,反应温度34℃时,反应时间3.Oh,此条件下,棕榈酸乙酯的产率为97.5％,该结果与模型预测值基本相符.