Polymerization of Fatty Acid Methyl Ester Using Acidic Ionic Liquid as Catalyst

The polymerization of fatty acid methyl ester was investigated using biodiesel as the feed in the presence of a Brönsted-Lewis acidic ionic liquid (IL). A synergetic effect of Brönsted and Lewis acid sites enhanced the catalytic performance of the IL. 1-(3-Sulfonic acid)-propyl-3-methylimidazole chlorozincinate ([HO3S-(CH2)3-mim]Cl-ZnCl2, molar fraction of ZnCl2 was 0.67) was an efficient catalyst for the polymerization. The effects of catalyst amount, reaction temperature, and reaction time were investigated. The optimum conditions for the polymerization were: biodiesel 15 g, m(biodiesel):m(IL) = 15:1, reaction temperature 240 °C, and reaction time 6 h, which gave 63.2% yield of dimeric acid methyl ester. The reusability of the IL was good and after it was used five times, the dimeric acid methyl ester yield was still > 63%.

摘要：以 Brönsted-Lewis 酸性离子液体为催化剂, 用于催化生物柴油中不饱和脂肪酸甲酯聚合制备二聚酸甲酯反应, 考察了催化剂种类、催化剂用量、反应温度和时间等因素对聚合反应性能的影响, 得到较佳的反应条件. 结果表明, 当以 1-(3-磺酸)-丙基-3-甲基咪唑氯锌酸盐[HO3S-(CH2)3-mim]Cl-ZnCl2 (ZnCl2 摩尔分数为 0.67) 为催化剂, 生物柴油 15 g, m(生物柴油):m(离子液体) = 15:1, 于 240 oC 下反应 6 h 时, 二聚酸甲酯收率为 63.2%, 其中三聚体含量小于 5%. 另外, 该催化剂重复使用 5 次后, 二聚酸甲酯收率仍超过 63%, 表明其具有较好的重复使用性能. 离子液体的 Brönsted 和 Lewis 酸位的协同效应显著提高了其催化活性.

Graphical abstractA Brönsted-Lewis acidic ionic liquid (IL) efficiently catalyzed the polymerization of fatty acid methyl ester. A synergetic effect of Brönsted and Lewis acid sites enhanced the IL catalytic activity.Figure optionsDownload full-size imageDownload as PowerPoint slide