菜籽油制备生物柴油共溶剂的选择

Selection of Cosolvent on Transesterification of Vegetable Oil for Biodiesel

生物柴油作为燃油替代品可以从食用油中大量获得,从而解决将来石油匮乏问题。针对菜籽油制备生物柴油酯的交换反应中,甲醇与菜籽油呈两相不互溶的主要问题,研究了添加共溶剂,使反应体系均相来提高反应速率与效率。以所选溶剂与甲醇的混合液为溶剂,菜籽油作溶质,分别在常温和60℃下做三元溶解度试验,选出乙醇、乙醚、四氢呋喃、1,2-环氧丙烷进行下一步比较;以普通菜籽油为原料,以甲醇为酰基受体,在加入不同共溶剂的条件下,进行碱催化酯交换反应,以酯化率和反应时间为考察指标,对共溶剂进行优选,发现以乙醇为共溶剂时,酯化率比空白提高了21.0%,且高于其他溶剂。研究结果表明,甲醇与乙醇的最佳摩尔比为3∶1。

Ternary phase solubility comprising vegetable oils,methanol and several solvent are obtained at ordinary temperature and 60 ℃.The higher temperature of the ternary system can reduce the quantity of cosolvent,which is needed to achieve single phase.Ethanol,ether,tetrahydrofuran and 1,2-epoxypropane are chosen,which will continue experiment.It is produced by transesterification in that vegetable oil is reacted with a methanol and varies solvent in presence of alkali as a catalyst.The results show that the conversion with ethanol as cosolvent is 21.0% higher than the blank,and much better than others.The best molar ratio of methanol and ethanol is 3∶1.