Solubility and diffusivity of hydrofluorocarbons in room-temperature ionic liquids

Gaseous absorption measurements of hydrofluorocarbons (trifluoromethane, difluoromethane, pentafluoroethane, 1,1,1,2-tetrafluoroethane, 1,1,1-trifluoroethane, and 1,1-difluoroethane) in l-n-butyl-3-methylimidazolium hexafluorophosphate ([bmim][PF6]) and 1-n-butyl-3-methylimidazolium tetrafluoroborate ([bmim][BF4]) were performed using a gravimetric microbalance at various isothermal conditions (temperatures between 283.15 and 348.15 K) and at pressures < 2 MPa. This report shows for the first time the solubility and diffusivity data for the hydrofluorocarbons in room-temperature ionic liquids and surprisingly large differences in the solubility among the hydrofluorocarbons. Experimental gas solubility data were successfully correlated with well-known solution models (Margules, Wilson, and NRTL activity coefficient equations). Diffusivities obtained from the time-dependent absorption data were well analyzed using a diffusivity model developed in this study. The present solubility and diffusivity data are also compared with those of CO2, studied in our previous study. © 2005 American Institute of Chemical Engineers AIChE J, 2006

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