Synthesis Of Acid Task-Specific Ionic Liquids And Their Applications On Synthesis Of Biodiesel

As one of biomass energys, biodiesel, presenting unique stable source and environmental friendliness, has aroused increasing interest of domestic and foreign scholars. Transesterification is one of the most widely used synthesis methods of biodiesel. However, the traditional alkali catalyzed transesterification has some defects, such as difficult recovery of catalyst, easy saponification of catalyst and so on. Meanwhile, the application of the traditional acid catalyzed transesterification was restricted for its difficult recovery of catalyst, corrosion equipment, slow reaction and much waste water. The solid base catalyst was unstable and deactivation, otherwise, the activity of the solid acid catalyst was relatively low. Therefore, a newly transesterification catalyst must have high activity, mild reaction, non-polluting, easy recovery and so on.Compared with the traditional organic reagents, room temperature ionic liquids (RTILs), presenting many unique physical and chemistry properties, such as adjustable structure, resistance of high temperature, easy recycling and so on, have been used as the synthesis catalyst of biodiesel. Now, most of the Lewis acid functional ionic liquids cannot be keep stable and active in the air and water. Meanwhile, the application of the Bronsted acid functional ionic liquids on the synthesis of biodiesel was less.In this article, a series of acid functional ionic liquids were synthesized based on the N-methylimidazole and pyridine. Moreover, the biodiesel were synthesized with these ionic liquids as the transesterification catalyst.The major contents are described as follows:1. The synthesis and characterization of acid task-specific ionic liquidsTwelve new acid task-specific ionic liquids, [HSO3PMIM][CH3SO3], [HSO3BMIM] [CH3SO3], [HSO3PMIM][CF3SO3], [HSO3BMIM][CF3SO3], [HSO3PMIM][CClSO3], [HSO3BMIM][CClSO3], [HSO3PPy][CH3SO3], [HSO3BPy][CH3SO3], [HSO3PPy] [CF3SO3], [HSO3BPy][CF3SO3], [HSO3PPy][ClSO3] and [HSO3BPy][ClSO3] were synthesized. The qualitative analysis was assisted by the FTIR spectra,1HNMR and TG, and the characteristics were studied.2. The application of acid task-specific imidazole ionic liquids on the synthesis of biodieselCompared with other six acid task-specific imidazole ionic liquids, [HSO3PMIM] [CH3SO3] showed high catalytic transesterification activity for the synthesis of biodiesel. The ionic liquid of [HSO3PMIM][CH3SO3] was used as the catalyst. According to the orthogonal experimental design, the optimal conditions of the synthesis of biodiesel with catalytic transesterification were catalyst (15%, wt%), methanol:oil=36:1, reaction time 4 h and reaction temperature 120℃. Under the optimum conditions, the biodiesel conversion could retain to 98.3%. Comparing to sulfuric acid, the ionic liquid of [HSO3PMIM][CH3SO3] offers the advantages of short reaction time, high conversion and recycling, which has broad qpplication and could meet the development needs of green chemistry.3. The application of acid task-specific pyridine ionic liquids on the synthesis of biodieselThe catalytic activity of six acid task-specific pyridine ionic liquids on the biodiesel was [HSO3PPy][CH3SO3]> [HSO3BPy][CH3SO3]> [HSO3PPy][CF3SO3]> [HSO3BP] [CF3SO3]> [HSO3BPy][ClSO3]> [HSO3PPy][ClSO3]. Therefore, the ionic liquid of [HS O3PPy][CH3 SO3] showed high catalytic transesterification activity for the synthesis of biodiesel. The ionic liquid of [HSO3PPy][CH3 SO3] was used as the catalyst. According to single factor experiment, the optimal conditions of the synthesis of biodiesel with catalytic transesterification were catalyst (10%, wt%), methanol:oil=24:1, reaction time 3 h and reaction temperature 120℃. Under the optimum conditions, the biodiesel conversion could retain to 95.9%. Comparing to sulfuric acid, the ionic liquid of [HSO3PPy][CH3 SO3] offers the advantages of short reaction time, high conversion and recycling, which has broad qpplication and could meet the development needs of green chemistry. Meanwhile, compared with the traditional base catalyst, the ionic liquid of [HSO3PPy][CH3SO3] used as the catalyst of biodiesel has the good water resistance and acid resistance.