Ionic liquid (IL)-metal mixtures are potential solvents for a variety of applications including metal electrodeposition, electrolytes for batteries, catalysis, and for separations processes such as liquid-liquid extraction. Despite the growing number of studies in the literature on the applications of IL-metal mixtures, there are a limited number of studies on the fundamental solubility of metal salts in ionic liquids. The solubility of a metal in an IL is fundamentally important to selecting the right IL for a potential process. In addition, solid liquid equilibria can provide fundamental insight into interactions between the solid and liquid and the resulting ability to predict solid liquid equilibria from pure component properties. In this work we investigate the solid liquid equilibria of binary mixtures of lithium bis(trifluoromethanesulfonyl)imide and three ammonium bis(trifluoromethanesulfonyl)imide ILs utilizing two methods. A visual method allows direct measurement between room temperature and 100°C, while differential calorimetry scans are interpreted to provide solid liquid equilibria information up to 250°C. The activity coefficients of the solid in the liquid are calculated from the measured phase equilibria and the pure component physical properties. The effect on the solid liquid equilibria of modifying the alkyl chain length of the ammonium cation is examined. The application of the Wilson Equation, which has been shown to be successful for molten salts with common anions1,2, is investigated for the systems measured. (1) Davison, S. M.; Sun, A. C. Thermodynamic Analysis of Solid–Liquid Phase Equilibria of Nitrate Salts. Ind. Eng. Chem. Res. 2011, 50, 12617. (2) Equilibria, F. P.; Scientific, E.; Company, P.; Chemistry, K.; Kyoto, N. Use of the Wilson Equation to Calculate Solid-Liquid Phase Equilibria in Binary and Ternary Systems. 1977, 1, 153.

Effects of alkyl chain length on lithium salt solubilities in ammonium Tf2N based ionic liquids

249th National Meeting (2015)

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