固定化脂肪酶Lipozyme TL IM催化菜籽油制备生物柴油稳定性的研究

Stability of Immobilized Lipozyme TL IM for Biodiesel Synthesis from Rapeseed Oil

研究了固定化脂肪酶Lipozyme TL IM催化菜籽油制备生物柴油的反应,探索了酶的预处理方式、后处理方式、反应温度、甲醇的加入方式等对酶活稳定性的影响。结果表明:将酶在油酸甲酯中浸泡0.5h,过滤后用菜籽油淋洗,在菜籽油中浸泡12h可以提高酶活的稳定性;多批次反应温度40℃为适宜;用丙酮洗涤酶除去甘油可以提高酶的稳定性;分三步加入甲醇的方式可以减轻甲醇对酶的毒害。Lipozyme TL IM经过预处理,40℃下进行多批次反应,每批反应24h,并在反应0、8、16h时加入1摩尔当量甲醇,并在8、16h以及反应结束时用丙酮洗涤固定化酶并重新投入体系,连续反应10批次,Lipozyme TL IM相对酶活仍有85%.

Lipozyme TL IM was used for the synthesis of biodiesel from rapeseed oil.The effects of pretreatment of the lipase,rinsing the lipase with solvents, reaction temperature, way of addition of methanol on the stability of the lipase were investigated. The experiment showed that the lipase was more stable when Lipozyme TL IM was preincubated in oleic acid methyl ester for 0.5 h, and subsequently in rapeseed oil for 12 h. 40 ℃was found to be the optimal reaction temperature of batch runs.The stability of the immobilized lipase was enhanced by rinsing the lipase with acetone to remove glycerol adsorbed on the support. A three-step methanolysis protocol was used to protect the immobilized lipase from inactivation by methanol. The pretreated Lipozyme TL IM was used to catalyse the methanolysis at 40℃reacting 24 h as one batch. One molar equivalent of methanol was added at various reacton time in 0, 8 or 16 h respectively at each batch. Acetone was used to remove glycerol at 8, 16 or 24 h respectively at one time and the immobilized lipase was reused for the next step or batch. The residual activity of lipase is still about 85% after being continuously reacted for 10 batches.