Synthesis Of A New Basic Ionic Liquid And Its Application In Catalyzing Preparation Of Biodiesel

Biodiesel is a typical renewable, low toxicity, new environmental-friendly biomass fuel, which is an ideal substitute for petroleum diesel. In recent years, the competition in the field of new energy technology focuses on biodiesel. As environmentally-friendly green solvent and new type of catalytic materials, ionic liquids also have aroused increasing interest of domestic all over the world. In this paper, combining these two emerging topics, preparation of biodiesel by transesterification of soybean oil and methanol was investigated by using new basic ionic liquid as catalyst.This paper focused on the synthesis of 1-butyl-3-methylimidazolium bromide ([Bmim]Br) which is a main ionic liquid intermediate. Based on this, two type of new basic ionic liquids 1-butyl-3-methylimidazolium hydroxide ([Bmim]OH) and 1-butyl-3-methylimidazolium imidazole ([Bmim]Im) were synthesized by functional design. The sample structures were characterized by 1H NMR, 13C NMR and IR.The effect of these two basic ionic liquids in catalyzing preparation of biodiesel was studied respectively. The results indicated that [Bmim]Im showed higher catalytic activity in the preparation of biodiesel by transesterification of soybean oil and methanol. Also this ionic liquid was stable and could be repeatedly used. Soybean oil and methanol were catalyzed by [Bmim]Im in batch stired-tank reactor (BSTR). The reaction conditions were optimized by means of orthogonal test together with the single-factor test. Under the optimal reaction conditions, which were the catalyst amount of 8.0%(wt), the methanol to soybean oil molar ratio of 6:1, the reaction time of 60 min and the reaction temperature of 60℃, the yield of biodiesel could reach 95.76%.The preparation of biodiesel by transesterification of soybean oil and methanol was catalyzed by [Bmim]Im in chemical micro-plant reactor (CMPR). Reaction conditions, such as the catalyst amount, the molar ratio of methanol to soybean oil, the reaction temperature and the reaction time were investigated and optimized. Under the optimal reaction conditions, which were the catalyst amount of 8.0%(wt), the methanol to soybean oil molar ratio of 6:1, the reaction time of 11.111 min and the reaction temperature of 60℃, the yield of biodiesel could reach 99.10%. Compared to the BSTR, CMPR not only shortened the reaction time, enhanced mass transfer and improved the yield of biodiesel, but also achieved a continuous and automatic reaction process.