Study On Separation Of O-Xylene And Styrene By Extractive Distillation

Styrene is an important chemical raw material. There is a great deal of styrene in the pyrolysis gasoline. However, it is difficult to remove styrene from pyrolysis gasoline. Styrene cannot be easily reclaimed from pyrolysis gasoline because of the closeness of the boiling point of styrene and other C8 aromatic hydrcarbons such as o-xylene (nbp, 144.41 oC) and styrene (nbp, 136.19 oC). Therefore, it is of great significance to study the o-xylene - styrene vapor-liquid equilibrium of the system and the separation process. Styrene is a heat-sensitive material, and it is likely to aggregate in high temperature conditions. In addition, measuring o-xylene experiment - styrene vapor-liquid equilibrium data by experiment for the system is more difficult. Hence, relevant data has been rarely reported. It is necessary to research extractive distillation system since it has not been studied sufficiently.In this paper, o-xylene and styrene separation process technology by extractive distillation was investigated. Around the themes of the vapor-liquid equilibrium and the extractive distillation we have done the research as follows:First, we determine the final work by the theoretical calculation of extractive distillation solvent and the experimental verification of the initial result.Secondly, the vapor-liquid equilibrium data was measured and the thermodynamics was studied. The vapor-liquid composition analysis was established, and determination of correction factors was measured. Binary and multi-determination of vapor-liquid equilibrium data and the binary data of the thermodynamic consistency were also tested.Then, the activity coefficient model was selected based on the above researches. And NRTL model parameters were correlated. The use of multivariate data on the adaptability of the model and model parameters were investigated.Finally, though the NRTL model parameters and the parameters of Aspen plus software provided by the article, we have compared the experimental data abtained in the small scale experiment of extractive distillation. The results showed that the software provided parameters superior to the parameters in Aspen. On this basis, four towers of the extractive distillation process for the separation process simulation and optimization were designed and the optimized process parameters have been abtained.