Study On Soybean Oil Transesterification Reaction Catalyzed By Brφnsted Acidic Ionic Liquids

As a kind of environmentally-benign newly material, Br(?)nsted acidic ionic liquids is less corrosive. It has not only the non-volatile as solid acid, but also has a high density of active acidic center like liquid acid. Therefore it has become a hot topic in research work at present.With the microwave reactor we synthesized six kind of water-stable and air-stable,-SO3H functionalized ioni liquids by using N-methylimidazole, pyridine and triethylamine with 1,4-butane-sultone and 1,3-propane-sultone. Their structure were characterized and evaluation by using NMR and IR, the acid of different Br(?)nsted acidic ionic liquids has been determined by automatic titrator and the acidity is characterized using pKa and the surface tensions were measured using a Wilhelmy plate apparatus and with the increasing of the determining temperature the surface tension appear to be a linear decrease.Under the same yield of [MimN(CH2)4SO3H][HSO4], microwave synthesis has a shorter time than hydrothermal synthesis. Compared with literature values, The structure can be determined by infrared and 1H NMR. Through the analysis by automatic titrator, we know the structure of ionic liquids has an effect on the acidic.With the weakening of acid anions, the acidity of ionic liquid has gradually weakened at the same cation.The acidity will increases with the growth of carbon chain cations. Ionic liquids as catalysts for the transesterification, the catalytic has an effect on the acid of ionic liquids, the stronger acid, the bigger conversion rate.pyridine has a better effect than imidazole and triethylamine in the same carbon chain length and anion.The longer carbon chain the higher catalytic activity with the same nitrogen functional groups. The ionic liquid 1-(4-sulfonic acid) butyl-methylimidazole hydrosulfate was used in this paper,and showed the optimal transesterification conditions is:m(catalyst):m(soybean oil)=0.05:l,n(meth= anol):n(soybean oil)=12:1, microwave power is 700W,the temperature is 70℃,and the reaction time is 4h, the yield of fatty acid methylester is 94.38%,and glycerol in the by-product is 89.23%.Without any treatment the ILs could be reused for six times.