Study On The Technology And Safety Of Preparing Ε-Caprolactone From Caprolactone Oligomer

Ε-caprolactone is a chemical intermediate used to synthesize various high-performance materials.The global demand forε-caprolactone is very large,while the production capacity and technology ofε-caprolactone in China are very limited.Therefore,China mainly rely on foreign resources to make up for the gap in domestic demand forε-caprolactone.It is of great significance to further explore the production technology ofε-caprolactone for industrial production ofε-caprolactone in China.Based on the above background,this paper focuses on the process of recovering caprolactone from caprolactone oligomer produced during the preparation ofε-caprolactone from cyclohexanone.The process mainly includes alkali washing,dehydration,depolymerization,cyclization and other steps to synthesizeε-caprolactone.Firstly,the optimum conditions for pretreatment of 20 g caprolactone oligomer were obtained by orthogonal experimental analysis as follows:alkali washing temperature was60℃,dosage of 1%Na OH solution was 150 g,alkali washing time was 2 h,dehydration temperature was 120℃.According to the single factor experiment method,the best depolymerization conditions of n-butanol,isobutanol and tert-butanol were investigated,and it was found that the depolymerization effect of n-butanol was the best.Under the conditions of depolymerization temperature 70℃,mass ratio of n-butanol to caprolactone oligomer 8,catalyst dosage 2%and depolymerization time 2 h,the depolymerization rate of caprolactone oligomer reached 98.68%,the yield ofε-caprolactone was 44.58%,and the content of 6-hydroxy butyl hexanoate was 48.02%.Secondly,the TS-1 catalyst modified by different metal ions was prepared by equal volume impregnation method,which was applied to the cyclization reaction of depolymerization products.The structural changes of the catalyst before and after modification were characterized by XRD,N₂adsorption-desorption,IR and UV-Vis.It was found that 5%Co²⁺/TS-1 catalyst had the largest pore size and BET specific surface area,and provided more active sites.Under the reaction conditions of cyclization temperature 300℃,catalyst dosage 5%and absolute pressure 1.3 KPa,the yield ofε-caprolactone could be increased to 68.5%.The exploration of this process has great application value for the industrial production ofε-caprolactone and provides a good direction for the development ofε-caprolactone production technology in China.Finally,according to the whole process route,we designed the PID of the 1000t/a caprolactone production plant,and divided the whole process flow into 8 process units and 27 analysis nodes.Hazard and operability analysis method（HAZOP）was used to identify the risks of each process unit,and put forward control measures to ensure the safety of the whole process production to meet the requirements.