Ammonia Solubilities in Room-Temperature Ionic Liquids

The solubilities of ammonia in the room-temperature ionic liquids 1-butyl-3-methylimidazolium hexafluorophosphate ([bmim][PF6]), 1-hexyl-3-methylimidazolium chloride ([hmim][Cl]), 1-ethyl-3-methylimidazolium bis(trifluoromethylsulfonyl)imide ([emim][Tf2N]), and 1-butyl-3-methylimidazolium tetrafluoroborate ([bmim][BF4]) have been measured for the first time. New static phase equilibrium cells have been constructed for the present experiment. Isothermally fixed temperatures are ∼283, 298, 323, 348, and 355 K, and six mixture compositions are prepared (from ∼10 mol % to 85 mol % ammonia) at the ambient temperature. The observed solubilities are high:  in fact, they are among the highest ever reported in the literature for room-temperature mixtures that contain ionic liquids. Observed pressure−temperature−composition (PTx) data have been successfully correlated with our previous equation of state (EOS) model. Possible applications of the present systems to the absorption cooling/heating cycle have been discu...