Study On The Purification Of 1, 2, 3-trimethylbenzene From Solvent Oil Via Extractive Distillation

1,2,3-trimethylbenzene is a very important chemical,pharmaceutical intermediate, which can be used for the preparation of alkyd, Tibet Musk, antiphlogistic and analgesic, etc. The by-product—190# solvent oil from aromatics separation unit in Jingzhou Petrochemical Company, contains large amount of 1,2,3-trimethylbenzene, accounting for about 40 percent of the total composition. 190# solvent oil is often used for blending gasoline or as ordinary solvent, causing great waste. It is significant in the purification of 1,2,3-trimethylbenzene from 190# solvent oil, however, because the boiling points of two highest content components-1,2,3-trimethylbenzene and indane are very close, they are difficult to separate by conventional distillation. The effective industrial purification technology of 1,2,3-trimethylbenzene from solvent oil has not been reported.Based on the above cases, this thesis conducted experimental research on the purification of 1,2,3-trimethylbenzene from 190# solvent oil via extractive distillation. This thesis mostly made the Prediction of extractant,conducted the experiment of batch extractive distillation, the experiment of vapor-liquid equi1ibria(VLE) and the data correlation. Meanwhile, the Process simulation and optimization were also investigated.The feasibility of DMSO and SULFOLANE were both predicted by UNIFAC model. The experimental results of vapor-liquid equilibria and batch extractive distillation show that both the solvents have obvious effect on enhancining relative volatility between 1,2,3-trimethylbenzene and indane. In addition, isobaric vapor-liquid equilibria data of four binary systems: 1,2,3-trimethylbenzene—indane, 1,2,3-trimethylbenzene—DMSO, 1,2,3-trimethylbenzene—SULFOLANE, indane—SULFOLANE were respectively measured by using a modified CE-2 vapor-liquid equilibrium still. The thermodynamic consistency of above systems was checked by area method. All the VLE data has not been reported yet. During the measurement, 1,2,3-trimethylbenzene+DMSO was found to form azeotropic mixture, so DMSO was abandoned, and SULFOLANE was selected as the extractant.The Wilson, NRTL, UNIQUAC models were used to correlate the VLE data and binary interaction parameters of three models were obtained. The average deviation between the experimental and the calculated values of NRTL model is the least. With NRTL model and the correlated binary interaction parameters, the extractive distillation process was simulated using Aspen Plus, and the optimized condition was proposed. Under this condition, the purity of 1,2,3-trimethylbenzene is over 99.8%, and the yield is over 94.0%. This research laid a foundation for the design of industrialized production.