Polymerization of Fatty Acid Methyl Ester Using Acidic Ionic Liquid as Catalyst
LIU Shiwei1, LI Lu1, YU Shitao1,*, XIE Congxia2, LIU Fusheng1, SONG Zhanqian1,3
1College of Chemical Engineering, Qingdao University of Science and Technology, Qingdao 266042, Shandong, China; 2College of Chemistry and Molecular Engineering, Qingdao University of Science and Technology, Qingdao 266042, Shandong, China; 3Institute of Chemical Industry of Forest Products, Chinese Academy of Forestry, Nanjing 210042, Jiangsu, China
Abstract 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 oC, 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%.