Global phase behaviors of trifluoromethane in ionic liquid [bmim][PF6]



In a recent article, Shariati et al. have reported that the global phase behavior of trifluoromethane and room-temperature ionic liquid [bmim][PF6] mixtures belongs to the type III fluid according to the classification of van Konynenburg and Scott. However, their assessment on the fluid classification was based on their very limited experimental data without any thermodynamic modeling. On the other hand, we have recently reported experimental solubility behaviors of trifluoromethane and [bmim][PF6] mixtures, together with those for other hydrofluorocarbon + ionic liquid mixtures and stated that the phase behavior of these mixtures belongs to the type V fluid mixture based on our equation-of-state model predictions. In order to confirm our predictions, important vapor-liquid-liquid equilibrium data have been obtained experimentally, and we show that the present mixture is definitely not the type III fluid but belongs to type V. Also, we demonstrate that our EOS model based on our vapor-liquid equilibrium (VLE) data alone has correctly predicted the global phase behavior of the present binary system, as well as unusually large negative excess molar volumes. © 2006 American Institute of Chemical Engineers AIChE J, 2006