Design and optimization of extractive distillation of benzene–n‐propanol with ionic liquid as entrainer

Abstract

BACKGROUND: The binary benzene-n-propanol azeotrope can be formed in chemical production. Extractive distillation is an important azeotrope separation technology and an ionic liquid is a type of excellent entrainer. Aspen Plus software was used to simulate the extractive distillation process. The separation performance of ionic liquids was evaluated in terms of total annual cost of the extractive distillation process. The separation mechanism of the azeotrope was quantitatively explained using intermolecular interaction energy. RESULTS: The thermodynamic properties databases of 1-octyl-3-methylimidazolium acetate, trioctylmethylammonium acetate and 1-decyl-3-methylimidazolium acetate were established in Aspen Plus software. The extractive distillation process was established through combining the thermodynamic properties of the three ionic liquids and the vapor-liquid equilibrium data of benzene-n-propanol-ionic liquid. The optimal operating conditions were obtained by minimizing the total annual cost of the separation process through a sequential iterative method. The interaction energy was calculated using density functional theory through Gaussian 09 software and used to explain the principle of the benzene-n-propanol azeotropic system separation.CONCLUSIONS: 1-Octyl-3-methylimidazolium acetate has the best separation performance among the three ionic liquids. The interaction energy can be used to screen and design ionic liquids in the process of benzene-n-propanol extractive distillation separation.

Process Simulation and Optimization on Ionic Liquids

“…Similarly, Zhang et al 179 minimized the TAC of an IL-based extractive distillation plant by programing a simulated annealing algorithm. In contrast, Li et al 182 and Wei et al 181 optimized the TAC of IL-based extractive distillation processes by adopting a sequential iterative method.…”

“…109,110 Aside from the study of the extractive distillation column's key variables, Kulajanpeng et al 284 completed the flowsheet with a previously optimized configuration scheme comprising a flash distillation unit and a stripping column for solvent regeneration, reducing the flow in the stripping column by exploiting the previous flash distillation. 306 In other studies, a second distillation column, 124,281,282 a flash distillation unit, 42,285,286 a stripping column, 182 two flash units, 292,301 or flash + stripping column + flash 179 were the most extended separation trains used to complete the process. The separation Another option that can be tuned at the process scale is the composition of a hybrid solvent to modulate key process indicators by changing the composition of the mixture, as stated in Section 4.5.…”

“…Regarding binary azeotropic mixtures of alcohols and other polar compounds, several examples are available in the literature, including methanol with methyl ethyl ketone, methyl acetate, , acetone, , and methylal; ethanol with ethyl acetate; n -propanol with ethyl propionate; and 2-propanol with diisopropyl ether, with S/F ratios (on mass basis) from 1 to 2 in almost all cases, leaving aside 0.03 for 2-propanol and diisopropyl ether, highlighting ILs based on dimethylphosphate and acetate anions completed with imidazolium cations having short alkyl groups. Another interesting family of binary azeotropic mixtures is that regarding benzene and polar compounds, such as methanol, 2-propanol, and acetonitrile, showing S/F ratios in mass in a narrow window (from 0.6 to 1.6) and ILs with imidazolium cations and acetate or tetrafluoroborate anions. The complete number of systems is completed with p-cresol/m-cresol separation, butadiene separation from acetonitrile or butene, and limonene/linalool separation.…”

Isobaric Vapor–Liquid Equilibrium Experiment of Methyl Acetate + Ethanol Containing Different Ionic Liquids at 101.3 kPa

“…In this case, if the azeotropic point can be eliminated entirely and the relative volatility near the azeotropic point can be expanded, the above problems can be eradicated. As chemical technologies that can eliminate azeotropism and expand relative volatility, azeotropic distillation, − pressure swing distillation, − and extractive distillation − are potentially good candidates. Compared with azeotropic distillation, extractive distillation has a relatively simple process, for the entrainer added will not form a new azeotropic system with the original components.…”

Multiscale Simulation and Mechanism Analysis of Cyclohexane/Ethanol Separation by Ionic Liquid Extractive Distillation

“…However, the study of the extractive distillation mechanism is crucial for the selection and molecular design of extractants. Therefore, in order to better separate cyclohexane and ethanol, it is of great significance to describe the separation mechanism of extractants based on QC calculations to select the appropriate extractant. , Based on QC calculations, Feng et al analyzed the possibility and mechanism of an IL as an extractant to separate acetic acid and water from the aspects of molecular configuration, charge density, and interaction energy and selected the best extractant [Bmim]­[BDP]. Woo et al found a new IL extractant for extractive distillation by molecular simulation.…”