Synthesis Of Acidic Polymeric Ionic Liquid And Its Application In Esterification

As the environmental protection requirements is becoming stricter and stricter,the traditional liquid acid can no longer meet the environmental protection requirements of modern industry.In order to overcome the disadvantages of homogeneous liquid acid catalysts in terms of equipment corrosion and separation,poly ionic liquids were used in this paper as catalysts,and their applications in esterification reaction were studied..As solid acid catalyst,poly ionic liquids had high catalytic activity,also reduces equipment corrosion,and can reduce subsequent treatment processes.In order to develop a suitable catalyst,a strongly acidic anion-cation copolymerized polymeric ionic liquid was synthesized by phenol-formaldehyde condensation in this paper.The successful synthesis of the polymeric ionic liquid was confirmed by infrared spectroscopy,and its thermal stability was studied by thermogravimetric analysis.Its microscopic morphology was observed by field emission scanning electron microscopy.The structure of the catalyst was determined by ¹³C Mas NMR.The acid density of the catalyst was determined by acid-base neutralization titration（2.2 mmol/g）.Taking the esterification of oleic acid and methanol as the target reaction,the catalytic activity of the catalyst was studied.The results showed that under the optimal conditions,the yield of methyl oleate reached 93.3%.After four cycles of experiments,the yield of methyl oleate did not decrease significantly.A powder type polymerized N-methyldiallylamine ionic liquid was synthesized by radical polymerization.The esterification of oleic acid and methanol was used to study the activity of the catalyst.FT-IR,TG,SEM and TEM were performed to characterize the catalyst.The pore structure of the catalyst was studied by N₂ adsorption and desorption and mercury intrusion method.Under the optimal process conditions,the yield of methyl oleate reached 95%.After 4 cycles of use,the catalytic activity did not decrease significantly,indicating that the catalyst has good reusability.A new type of polyionic liquid（PIL-S）was synthesized by condensation of phenolic hydroxyl group-containing ionic liquid and formaldehyde.Various characterization techniques were performed,and the results confirmed the presence of high acidity（4.5mmol/g）and good thermal stability of PIL-S.PIL-S has a decomposition temperature of240°C and is suitable for the production of ester.The excellent performance of poly ionic liquid catalyst（PIL-S）in the esterification is owing to the good properties.Also,the good catalytic activity of PIL-S can be found in other types of esterification.In order to find a catalyst with high catalytic activity,poly ionic liquid with both Br（?）nsted acid and Lewis acid was synthesized by radical polymerization.The successful synthesis of the poly ionic liquid was confirmed by infrared spectroscopy,and thermogravimetric analysis was performed.The thermal stability was studied.The micro-morphology of synthesized catalyst was observed by field emission scanning electron microscopy.The results of adsorption and desorption of N₂ showed that the poly ionic liquid had mesopores and macropores,which facilitated the contact between the substrate and the active site.Taking the esterification of acetic acid and n-butanol as the target reaction,the catalytic activity of the catalyst was studied.The results show that under the optimal conditions,the yield of n-butyl acetate reaches 98.0%.