Research On Preparation Of Acid-functionalized Ionic Liquids And Immobilization

The transesterification reaction is one of the most important reactions in organic chemistry, but there are many shortcomings of the conventional transesterification catalysts. The acid-functionalized ionic liquids, which are novel acid catalysts, exhibit high catalytic activity, and less environmental pollution. The supported ionic liquids, which are environmentally friendly catalysts, exhibit high catalytic activity of ionic liquids and readily recycled of solid catalysts. Synthesis and application of the acid-functionalized ionic liquids and the solid supported ionic liquids based on the model reaction which using 2-butyl acetate and methanol as the starting material to synthesize 2-butanol will be studied.(1) In this paper, eleven acid-functionalized ionic liquids were synthesized and characterized. NMR and FT-IR spectrometer shown that the synthesis method was feasible and high purity of ionic liquid could be obtained. The acid strength of ionic liquids was characterized by UV-visible spectroscopy. Acid strength had closely related with structure, and [Ps-mim]HS04 was the the strongest acid. The solubility of acid-functionalized ionic liquids in the reaction system was measured.(2) In a batch reactor, the catalytic activity of acid-functionalized ionic liquids in the transesterification was investigated. The [Ps-mim]HS04 shown the best catalytic activity. The influence of the catalyst concentration, initial molar ratio of methanol/2-butyl acetate and reaction temperature on the reaction process were studied. Under the optimized conditions, the conversion of 2-butyl acetate was 91.20%. There was no appreciable derease of catalytic activity of the ionic liquid [Ps-mim]HSO4 after being reused for four cycles.(3) In this paper, the supported ionic liquids immobilized on Merrifield resin(MR), Silica and SBA-15 were prepared through the chemical covalent bond method. Through characterize of them by FT-IR spectrometer, Elemental Analyzer and N2-Sorption isotherm. Then had been used as catalysts for transesterification reaction. The catalytic activity of the supported ionic liquids in the transesterification reaction was measured. The [SBA-15-Ps-im]HSO4 shown the best catalytic activity. The reaction conditions, such as the catalyst concentration, initial molar ratio of methanol/2-butyl acetate and reaction time, were optimized. Under the optimal reaction conditions the conversion of 2-butyl acetate was 89.23%. The supported catalyst could be reused. After repeated use, the conversion of 2-butyl acetate had decreased. Explore the the reasons by characterization, The characterization results were shown the activity lose caused by the bond rupture of ionic liquids and carrier.