Data Determination and Process of Vapor–Liquid Equilibrium of Butane–Butene System by Complex Extractive Distillation Using Salt

Abstract

The refined utilization of various parts of hybrid residual C4 has received increasing attention, but the mixed C4 is difficult to separate due to complex components and close boiling points. This paper proposes an innovative separation method using complex extractive distillation by adding cuprous chloride ethanolamine (C2H7NO–CuCl) into the conventional extractant, as a complexing agent. The vapor–liquid equilibrium (VLE) data were measured for six different systems, namely, the mixed C4–dimethylformamide (DMF) system and the mixed C4–DMF–C2H7NO–CuCl system, the mixed C4–acetonitrile (ACN) system and the mixed C4–ACN–C2H7NO–CuCl system, and the mixed C4–methyl–ethyl ketone (MEK) system and the mixed C4–MEK–C2H7NO–CuCl system. Results showed that the relative volatility of butane–butene solution was significantly increased with the addition of the complexing agent systems. After careful consideration of various influencing factors, the mixed C4–MEK–C2H7NO–CuCl system was selected as the best extraction separation system, and technological experiments were carried out to further explore its feasibility and advanced nature. Results showed that when the solvent-to-feed ratio (S/F) was 12.5, the reflux ratio of extractive distillation column (R 1) was 1.5, and the reflux ratio of solvent recovery column (R 2) was 2.5, the purity of butene was more than 97.0%, and the separation yield was more than 95.0%. Furthermore, the solvent-to-feed ratio of complex extractive distillation was only 70% of ordinary extractive distillation, the reflux ratio was only 60% of ordinary extractive distillation, and the stripping temperature of the complex extractive distillation column was only about 423.15 K, which was lower than that of the ordinary extractive distillation column.

Vapor–Liquid Equilibrium Data Determination and Model Correlation for 1-Octene + 1,4-Dioxane, 2-Octanol + 1,4-Dioxane, 1-Octene + Isophorone, and 2-Octanol + Isophorone Systems at 101.3 kPa

“…On the other hand, the method of using isophorone organic solvent to enhance the liquid–liquid distribution of cyclohexene to improve the cyclohexanol yield with a solid acid as catalyst published in the US patent, the isophorone does not azeotropic with the cyclohexanol, which makes the product and isophorone easy to separate, and the isophorone can be stable under the hydration reaction conditions. The advantages of isophorone as a cosolvent for olefin hydration reactions have been studied in the literatures. − Since distillation accounts for a significant proportion of chemical separation operations, vapor–liquid phase equilibrium (VLE) data are in great demand. , The data can be obtained directly by specific experimental methods or by estimating the calculated data according to specific theoretical and empirical methods. − , For example, Kurzin et al used the gas chromatography method to determine the VLE data of the 1,4-dioxane + water + tetrabutylammonium bromide system at 288, 298, and 308 K at atmospheric pressure. Then, the liquid–liquid and vapor–liquid phase behaviors were correlated and derived using an electrolyte nonrandom two-liquid model.…”