Study On The Catalytic Synthesis Of Diols By Confined Ionic Liquids

Dihydric alcohols such as ethylene glycol（EG）and propylene glycol（PG）are important basic raw materials in the chemical industry,mainly used in the production of polyester fiber,film,engineering plastics,etc.To solve the problems of high water ratio,harsh reaction conditions,high energy consumption and low yield in traditional hydration process,green ionic liquid catalysts with low water ratio and high yield are developed.The main research contents and innovative achievements of this dissertation are as follows:（1）Four kinds of imidazolium acetate ionic liquids are developed and applied to the hydration of ethylene oxide（EO）.The result shows that the catalysts have good catalytic performance,and the conversion of EO decreases with the increase of cation chain length.The optimal reaction conditions are determined by using[EMim]CH₃COO as the model catalyst.At this time,the conversion of EO reaches 99.0%,and the selectivity of EG reaches over 98.0%.（2）Three kinds of 1-ethyl-3-methylimidazolium carboxylate ionic liquid catalysts are developed based on the best chain length of imidazolium cations.The result shows that the selectivity of EG decreases with the increase of anion chain length.The optimal reaction conditions are determined by using imidazolium carboxylate[EMim]HCOO as the model catalyst.At this time,the conversion of EO is 99.8%,and the selectivity of EG is 99.1%.（3）The confined ionic liquid is synthetized by the formation of silicagels via sol-gel technique,which realizes the heterogeneous phase of ionic liquid.The result shows that low concentration of ionic liquids is more conducive to the dispersion of the active sites,improving the catalytic activity and achieving the optimal catalytic performance.Compared with the unsupported ionic liquid,the amount of used ionic liquid is reduced by 80%.The method,herein,not only significantly saves the amount of ionic liquid,but also realizes the homogeneous catalytic effect of heterogeneous catalyst.