New eutectic ionic liquids for lipase activation and enzymatic preparation of biodiesel
作者:Hua Zhao、Gary A. Baker、Shaletha Holmes
DOI:10.1039/c0ob01011a
日期:——
The enzymatic preparation of biodiesel has been hampered by the lack of suitable solvents with desirable properties such as high lipase compatibility, low cost, low viscosity, high biodegradability, and ease of product separation. Recent interest in using ionic liquids (ILs) as advanced reaction media has led to fast reaction rates and high yields in the enzymatic synthesis of biodiesel. However, conventional (i.e., cation–anion paired) ILs based on imidazolium and other quaternary ammonium salts remain too expensive for wide application at industrial scales. In this study, we report on newly-synthesized eutectic ILs derived from choline acetate or choline chloride coupled with biocompatible hydrogen-bond donors, such as glycerol. These eutectic solvents have favorable properties including low viscosity, high biodegradability, and excellent compatibility with Novozym® 435, a commercial immobilized Candida antarctica lipase B. Furthermore, in a model biodiesel synthesis system, we demonstrate high reaction rates for the enzymatic transesterification of Miglyol® oil 812 with methanol, catalyzed by Novozym® 435 in choline acetate/glycerol (1 : 1.5 molar ratio). The high conversion (97%) of the triglyceride obtained within 3 h, under optimal conditions, suggests that these novel eutectic solvents warrant further exploration as potential media in the enzymatic production of biodiesel.
生物柴油的酶促制备受限于缺乏具有高脂肪酶兼容性、低成本、低粘度、高生物降解性和易于产品分离等所需特性的合适溶剂。最近对使用离子液体(ILs)作为先进反应介质的兴趣使得生物柴油的酶合成反应速率快、产率高。然而,基于咪唑盐和其他季铵盐的传统(即阳离子-阴离子配对)离子液体仍然过于昂贵,无法在工业规模上广泛应用。在这项研究中,我们报道了新合成的由乙酸胆碱或氯化胆碱与生物相容性氢键供体(如甘油)结合而成的共晶离子液体。这些共晶溶剂具有低粘度、高生物降解性以及与Novozym® 435(商业化的固定化南极假念珠菌脂肪酶B)优良兼容性等有利特性。此外,在模型生物柴油合成系统中,我们展示了在乙酸胆碱/甘油(1:1.5摩尔比)中,由Novozym® 435催化的Miglyol®油812与甲醇的酶催化酯化反应具有高反应速率。最优条件下,三酯的高转化率(97%)在3小时内实现,表明这些新型共晶溶剂作为生物柴油酶生产潜在介质值得进一步研究。