Computer-Aided Molecular Design of New Task-Specific Ionic Liquids for Extractive Desulfurization of Gasoline

Abstract

New ionic liquids (ILs) for extractive removal of organic sulfur compounds from gasoline are proposed following the results of computer-aided molecular design (CAMD), comprising application of the extensive group contribution model for infinite dilution activity coefficients of molecular solutes in ILs presented previously [J. Chem. Inf. Model. 2016, 56, 1420−1437. Infinite dilution selectivity of model system thiophene/n-heptane was adopted as a benchmark property. The proposed structures, selected on the basis of screening of almost 25 800 cation−anion combinations, were synthesized and characterized from the point of view of their thermal behavior and fundamental physical properties, density, and dynamic viscosity. Besides, general remarks regarding an impact of cation/anion structure on extraction selectivity are highlighted and discussed based on the calculations carried out. Liquid−liquid phase equilibrium diagrams in ternary systems {IL + thiophene + n-heptane} were determined at T = 308.15 K in the entire range of feed composition in order to verify robustness and reliability of the applied CAMD approach. Finally, performance of the proposed extraction solvents in thiophene/n-heptane separation is confronted against 39 other ILs reported in the literature.

Experimental Data of Fluid Phase Equilibria- Correlation and Prediction Models: A Review

“…It is possible to predict the structure of new compounds, or ILs of different cations and anions for the chosen separation process. The method is shown, for example, for the prediction of the best ILs for the desulfurization of fuels [137]. In general, the deviation of predictions in ternary system is strongly dependent on the prediction of LLE compositions in binary mixtures.…”

Effect of Cation Structure in Quinolinium-Based Ionic Liquids on the Solubility in Aromatic Sulfur Compounds or Heptane: Thermodynamic Study on Phase Diagrams

“…For decades, new, alternative methods have been proposed such as extractive desulfurization (EDS) [3]. The EDS concept postulates the use of a suitable solvent for the selective separation of sulfur compounds including ionic liquids (ILs) [3][4][5][6][7]. The dominant advantages of EDS compared to HDS are the mild conditions of the process without the use of expensive hydrogen and complex metal catalysts.…”

“…The potential extractants are selected on its polarity. The literature proposes various solutions, among which two groups of compounds dominate: deep eutectic solvents (DES) and ionic liquids (ILs) [3][4][5][6][7].…”

“…ILs reveal low volatility and the possibility of designing their structure, which make them attractive for use in many branches of the chemical industry including extraction processes and environmental clean-up technologies [4][5][6]. ILs are known for high values of selectivity of extraction of aromatic sulfur compounds (for example, thiophene) from aliphatic hydrocarbons (fuels, for example, heptane) in comparison with organic solvents used now on an industrial scale such as NMP or sulfolane [7].…”

Polyoxometalate-based silica-supported ionic liquids for heterogeneous oxidative desulfurization in fuels

“…Ionic liquids (ILs) with unique physicochemical properties have been widely employed as solvents, extractants, templates and precursors (Zhou and Qu 2017;Dai et al 2017). In the desulfurization process, ionic liquids are often used as extractants (Paduszyński et al 2017;Moghadam et al 2017), but the sulfur removal is not so satisfactory. Thus, polyoxometalates (POMs), a family of transition metal-oxide clusters with specific physical properties and controllable redox and properties, are often introduced as anions to the family of specific ILs (Zhao et al 2012;Zhu et al 2013).…”