New Process Development Of 1,3-dioxolane By Reactive And Extractive Distillation Technology

There exist disadvantages of low conversion, high energy consumption, serious pollution and large equipment investment in the traditional 1, 3-dioxolane(DOL) production process. For this, Reactive and Extractive Distillation (RED) was introduced in order to improve the defects. Reactive Distillation(RD) and Extractive Distillation(ED) were integrated in the RED column.As a result, reaction was improved by distillation while distillation was improved by ED. The conversion of the material and the purity of the product were enhanced by using RED technology as well as the equipment investment and energy consumption were reduced. Because of the introduction of chemical reaction and ED, the variables were highly coupled leading to complicated design and operation of RED process. The continuous production of DOL using RED technology was studied systematically through the method of combining experiment and ASPEN PLUS simulation together.The reaction between formaldehyde and ethylene glycol was studied by small scale experiment. The experiment results showed that the reaction was a second reaction and the reaction kinetic equation was:RED pilot plant was constructed based on the small scale experiment to carry out continuous production. By controlling proper reflux ratio, a continuous high purity product of DOL was recovered from the top of the column while water was collected from the bottom. The process operating parameters, concentration of each component and temperature on each tray were systematically researched to provide data for industrial design.The process was simulated by ASPEN PLUS and the simulation result showed good agreement with the pilot experiment which indicated that the software can be used for DOL RED process simulation.Preliminary design of the continuous RED process for DOL production was carried out, the process equipment parameters and technological conditions was designed and optimized by the use of computer simulation. The appropriate operating parameters were: total plate number 21,with 2 for distillation, 9 for extraction, 5 for reaction and 5 for stripping; reflux ratio 1.5; feeding ratio n(ethylene glycol): n(formaldehyde) =1.05:1; ethylene glycol fed at room temperature. Simulated based on this condition, the purity of DOL was up to 94.7%.In terms of refining products, ED method, molecular sieve dehydration method and sodium chloride salt-out and molecular sieve dehydration combined methods were systemically researched. The results showed that sodium chloride salt-out and molecular sieve dehydration combined method was the most appropriate dehydration method. Under the condition of sodium chloride feeding ratio 7.5%, molecular sieve and refined product feeding ratio 1:1, the DOL product purity was up to 99.9% which had met the product quality requirements.