Salis Andrea, Pinna Marcella, Monduzzi Maura, Solinas Vincenzo
Dipartimento di Scienze Chimiche, Università di Cagliari, CSGI, Cittadella Monserrato, S.S. 554 Bivio Sestu, 09042 Monserrato, Cagliari, Italy.
J Biotechnol. 2005 Sep 29;119(3):291-9. doi: 10.1016/j.jbiotec.2005.04.009.
Oleic acid alkyl esters (biodiesel) were synthesised by biocatalysis in solvent-free conditions. Different commercial immobilised lipases, namely Candida antarctica B, Rizhomucor miehei, and Pseudomonas cepacia, were tested towards the reaction between triolein and butanol to produce butyl oleate. Pseudomonas cepacia lipase resulted to be the most active enzyme reaching 100% of conversion after 6h. Different operative conditions such as reaction temperature, water activity, and reagent stoichiometric ratio were investigated and optimised. These conditions were then used to investigate the effect of linear and branched short chain alcohols. Methanol and 2-butanol were the worst alcohols: the former, probably, due to its low miscibility with the oil and the latter because secondary alcohols usually are less reactive than primary alcohols. Conversely, linear and branched primary alcohols with short alkyl chains (C(2)--C(4)) showed high reaction rate and conversion. A mixture of linear and branched short chain alcohols that mimics the residual of ethanol distillation (fusel oil) was successfully used for oleic acid ester synthesis. These compounds are important in biodiesel mixtures since they improve low temperature properties.
在无溶剂条件下通过生物催化合成了油酸烷基酯（生物柴油）。测试了不同的商业固定化脂肪酶，即南极假丝酵母B、米黑根毛霉和洋葱假单胞菌，考察它们催化三油酸甘油酯与丁醇反应生成油酸丁酯的性能。结果表明，洋葱假单胞菌脂肪酶活性最高，6小时后转化率达到100%。研究并优化了反应温度、水分活度和试剂化学计量比等不同操作条件。然后利用这些条件研究直链和支链短链醇的影响。甲醇和2-丁醇是最差的醇类：前者可能是由于其与油的互溶性低，后者是因为仲醇通常比伯醇反应活性低。相反，具有短烷基链（C(2)-C(4)）的直链和支链伯醇显示出高反应速率和转化率。一种模拟乙醇蒸馏残余物（杂醇油）的直链和支链短链醇混合物成功用于油酸酯合成。这些化合物在生物柴油混合物中很重要，因为它们改善了低温性能。
