One of the most important processes in organic synthesis is the production of vinyl chloride using a balanced method. The reaction mixture formed during the pyrolysis stage of 1,2-dichloroethane (DCE) contains, besides vinyl chloride and unreacted DCE, several by-products, including tetrachloromethane (TCM) and trichloroethylene (TCE). An alternative to the existing method for purifying recycled DCE from impurities may be one that eliminates the chlorination step and is based on extractive distillation (ED) to obtain high-purity DCE. The aim of this study is to find out the potential separating agents for the extractive distillation of the tetrachloromethane–1,2-dichloroethane–trichloroethylene mixture.
We conducted a computational experiment using the Aspen Plus®v.10.0 software package. The Non-Random Two-Liquid (NRTL) equation is used for mathematical modeling of the vapor–liquid equilibrium (VLE).
Based on experimental VLE data, the parameters of the binary interaction of the TCM-DCE-TCE system's components are estimated. The error in describing experimental data was <3%. VLE modeling in the TCM-DCE-TCE system at a pressure of 760 mm Hg revealed that the binary TCM-TCE mixture is characterized by a similar volatility of components, while the TCM-DCE and DCE-TCE systems contain positive azeotropes. The structure of the VLE diagram of the separable system excludes the possibility of complete separation of the TCM-DCE-TCE mixture by conventional distillation. Therefore, special separation methods, such as ED, are necessary. In the search for potential separating agents (SAs), 76 substances used in the chemical industry as solvents and SAs were considered. Substances satisfying the requirements for SAs were selected, and VLE modeling was performed in derivative TCM-DCE-TCE-SA systems . The coefficients of the relative volatility of components in the presence of various SAs and the selectivity of each were calculated.
We noticed some of the most selective SAs are furfural (increases the volatility of TCM relative to DCE and TCE) and toluene (increases the volatility of DCE relative to TCE).
