Liquid-liquid Equilibrium For Extraction Separation Of Toluene And Cyclohexane Using Dimethyl Sulfoxide/Dimethyl Sulfoxide And N,N-Dimethylformamide

In the background of the industry development,there is extending demand of the petrochemical products.As the foundation of the petrochemical engineering,optimizing the ethylene feedstock is an essential problem to be solved.Aliphatic hydrocarbon is an important part of the raw material of ethylene production industry,and its purity affects the ethylene yield directly.Therefore the primary work is the segregation of aromatic and aliphatic hydrocarbons.This paper aims at furthering the area of the separation of aromatic/aliphatic mixtures,chooses one of the representatives of the aromatics content toluene as the object of the investigate and focuses on the separation of toluene and cyclohexane.The experiment in this paper explored on the single extract solvent dimethyl sulfoxide(DMSO)and mixed extraction solvent dimethyl sulfoxide+N,N-dimethyl formamide(DMSO+DMF)respectively,aiming at finding the effect of the different extract solvent to the toluene/cyclohexane separation performance.Extractive distillation and azeotropic distillation as the conventional technologies have been used for a period of time.However,the application based on technologies above is limited by its high energy consumption.As emerging technologies of separation,the application of absorption and pervaporation remain to be further development.In this paper,the separation process employs the liquid-liquid extraction separation technology,and the key to this technology is choosing a suitable extraction solvent.The experiment research on the single extract solvent DMSO and mixed extraction solvent(DMSO+DMF)at 298.15 K and 303.15 K respectively.The primary contents of the experiment are that: Measured the correction factor of the toluene,cyclohexane,DMSO and DMF.Equilibrium data of the ternary system cyclohexane+toluene+DMSO and the quaternary system cyclohexane+toluene+DMSO+DMF are measured at 298.15 K and 303.15 K temperatures.The selectivity coefficient of the solvent and distribution coefficient of the solute are calculated.For the ternary system,the selectivity coefficient were increased with the decreases of the raffinate phase content,the maximum of it reached at 18.99 and 18.61 in the conditions of 298.15 K and 303.15 K.For the quaternary system,the maximum of the selectivity coefficient reached at 19.76.In order to investigate whether the liquid-liquid equilibrium data are in good agreement,the experimental data of the ternary system and quaternary system are correlated by Othmer-Tobias equation,Hand equation and NRTL equation.The results indicate that Othmer-Tobias equation and Hand equation are well correlated for the two systems.The root mean square errors(RMSD)of the equilibrium data calculated by NRTL equation are less than 0.44.