Synthesis And Applications In Esterification Of Immobilized Ionic Liquid

Esterification is one of the most important chemical reactions,which is the reaction of alcohol and carboxylic acid or inorganic acid to produce ester and water.Organic carboxylic acid esters can be regarded as a kind of important fine chemical products,commonly used in rubber and plastic plasticizer,spices,surfactant,cosmetics and medicine,etc.The traditional esterification catalyst can easily lead to equipment corrosion,environment pollution,inefficient and uneconomical process.Therefore,with the increasing attention of the global industry and academia to the non pollution cleaning technology,and the growing shortage of resources,the study of environmental protection with high catalytic performance of the catalyst is becoming increasingly important.In the search for a new type of catalyst,it is gradually found that the ionic liquid with excellent properties can be used to instead of the traditional medium for the esterification reaction.Four kinds of caprolactam task-specific ionic liquids(TSILs)were prepared and characterized with low price caprolactam as raw material.The catalytic activities of these acidic ionic liquids were investigated by the esterification of acetic acid with ethanol and were compared with 3 kinds of SO3H-functionalized ionic liquids with different nitrogen heterocycles and concentrated sulfuric acid.The optimal conditions for the synthesis of ethyl acetate were obtained.Under the optimal reaction conditions,its reusability and catalytic effect were investigated.To decrease the amount of ionic liquid and facilitate the separation of catalyst from the product,a novel Br?nsted acidic ionic liquid catalyst 1-(3-sulfopropyl)caprolactam hydrogen sulfate([C3SO3HCP]HSO4)supporting on silica gel,SBA-15 and MCM-41 were prepared through covalent bond grafting method.The catalytic activities of the immobilized ionic liquid were investigated by the esterification of succinic anhydride with ethanol,and then the ionic liquids with the best catalytic effects were choosed.The properties of samples were characterized by FT-IR,TG,XRD,BET and TEM.The results showed that [C3SO3HCP]HSO4 had been successfully immobilized onto the SBA-15.And the immobilized ionic liquid catalyst(IL/SBA-15)had good thermal stability and activity,which could be separated easily from the reaction system.At the same time,the process conditions of esterification reaction were optimized,and the immobilized ionic liquid of reusability was investigated.At last,the catalytic effect of pure ionic liquid and immobilized ionic liquid was compared with each other.