Solubility of Hydrogen Chloride in Three 1‑Alkyl-3-methylimidazolium Chloride Ionic Liquids in the Pressure Range (0 to 100) kPa and Temperature Range (298.15 to 363.15) K

To study the possibility of using ionic liquids (ILs) as a novel solvent for the absorption of hydrogen chloride (HCl) from the industrial tail gases, the solubility of HCl gas in three ILs has been measured at four temperatures, (298.15, 323.15, 348.15, and 363.15) K, in the pressure range of (0 to 100) kPa. The ILs used are 1-butyl-3-methylimidazolium chloride ([Bmim]­Cl), 1-hexyl-3-methylimidazolium chloride ([Hmim]­Cl), and 1-octyl-3-methylimidazolium chloride ([Omim]­Cl). The results indicate that these ILs show high solubility for HCl gas, and the solubility decreases with the increasing length of the alkyl substitutes of the ILs, following the order [Bmim]Cl > [Hmim]Cl > [Omim]­Cl. The solubility of HCl in [Bmim]Cl at 298.15 K is about 0.68 mole fraction at ca. 100 kPa partial pressure of HCl, which is much higher than that of 36.5 % HCl aqueous solution. The solubility of different ILs is discussed in detail, and the experimental data (<i>P</i>–<i>T</i>–<i>x</i>) are correlated successfully by an empirical relation