| Using N-methylimidazole and concentrated sulfuric acid as raw materials, a noval Brφnsted acidic ionic liquid [Hmim]HSO4 was synthesized and used as catalyst in the esterification reaction of oleic acid and methanol. The chemical structure of [Hmim]HSO4 was characterized by FTIR and the oleic acid methyl oleate was qualitatively analyzed by GC-MS. The results showed that the optimal synthesis conditions of oleic acid methyl oleate catalyzed by ionic liquid [Hmim]HSO4 were obtained as follows: molar ratio of oleic acid to methanol 1∶4 (0.04 mol oleic acid), catalyst dosage 3.5 mL and reaction time 6 h. Under these conditions, the esterification rate of oleic acid reached 92.5%. The esterification rate of oleic acid was still above 85% when ionic liquid [Hmim]HSO4 had been reused for nine times. Therefore, the ionic liquid [Hmim]HSO4showed good catalytic activity and was easily separated from product, which overcame the shortcomings of traditional inorganic acid catalysis. |
