Extractive distillation with ionic liquids: A review

Abstract

Extractive distillation is commonly used for the separation of azeotropic or close-boiling mixtures in the chemical industry. During the past decade, the use of ionic liquids (ILs) as entrainers has received considerable attention due to their unique advantages when applied in extractive distillation. This work is devoted to providing an easy-to-read and comprehensive review on the recent progress made by chemical engineers, focusing on the issues of predictive thermodynamic models, structure-property relations, separation mechanisms, and process simulation and optimization. This review spans from the molecular level to the industrial scale, to provide a theoretical insight into the molecular interactions between ILs and the components to be separated. Moreover, a comprehensive database on the vapor-liquid equilibria (VLE) and activity coefficients at infinite dilution concerning ILs is provided as Supporting Information. Concluding remarks are made on the unsolved scientific issues with respect to this promising special distillation technology.

Screening of ionic liquids for solvent-sensitive extraction –with deep desulfurization as an example

“…Therefore, a reliable and efficient simulation-based solvent screening method is highly desirable. Until now, a number of theoretical models have been applied for modeling phase behaviors of IL-involved systems, e.g., the classical liquid activity coefficient models NRTL and UNIFAC (Alonso et al, 2007;Lei et al, 2008Lei et al, , 2014Rodríguez-Cabo et al, 2013;Tian et al, 2010) and models based on statistical associating fluid theory PC-SAFT (Paduszynśki and Domanśka, 2012). Nevertheless, these models present a limited predictive capability since they normally require experimentally fitted parameters.…”

Isobaric vapor–liquid equilibrium for methyl acetate+methanol system containing different ionic liquids at 101.3kPa

“…ILs possess properties of negligible vapor pressure, high selectivity, low toxicity and corrosion, and good solubilities for various of chemicals [7,8]. Moreover, ILs as entertainers combine the advantages of a liquid solvent (easy operation) and a solid salt (high separation ability) [9]. However, the thermodynamic data of IL-containing systems are still scarce, which are essential for further design of extractive distillation process.…”

Separation of benzene and thiophene with a mixture of N -methyl-2-pyrrolidinone (NMP) and ionic liquid as the entrainer

“…At present, five types of entrainers are used in extractive distillation, i.e., liquid solvents, solid salts, mixtures of liquid solvents and solid salts, hyperbranched polymers, and ionic liquids (ILs) [10][11][12][13][14][15][16][17][18][19][20][21][22]. The comparison among these entrainers has been summarized in our previous publication [23]. Traditionally, N-methyl-2-pyrrolidinone (NMP) has been used commercially as an entrainer in the extractive distillation process [24][25][26], but NMP is a volatile organic compound, which is inevitably entrained in the product stream.…”