Vapor−Liquid−Liquid Equilibria of Hydrofluorocarbons + 1-Butyl-3-methylimidazolium Hexafluorophosphate

Abstract

In recent reports, we measured the vapor−liquid−liquid equilibria (VLLE) of trifluoromethane (R-23) and pentafluoroethane (R-125) with a room-temperature ionic liquid (RTIL), 1-butyl-3-methylimidazolium hexafluorophosphate [bmim][PF6], using a volume−mass measurement method along various isotherms. In the present work, we complete similar investigation of VLLE for the methane and ethane series of hydrofluorocarbons (HFCs) in [bmim][PF6]. Compounds studied here are fluoromethane (R-41), 1,1,1,2-tetrafluoroethane (R-134a), 1,1,1-trifluoroethane (R-143a), 1,1-difluoroethane (R-152a), and fluoroethane (R-161) in [bmim][PF6]. Observed VLLE behaviors are consistent with the earlier predictions by our equation-of-state (EOS) model, which showed partial immiscibilities in the HFC-rich side solutions, indicating type-III or type-V mixtures according to the Konynenburg−Scott classification. Thus, the present study as well as those with R-23 and R-125 reasonably validate our EOS model. In addition, very large negative excess molar volumes have been observed for all the studied systems, similar to that observed for mixtures with R-23 and R-125.

Phase Behavior of N2O and CO2 in Room-Temperature Ionic Liquids [bmim][Tf2N], [bmim][BF4], [bmim][N(CN)2], [bmim][Ac], [eam][NO3], and [bmim][SCN]

“…High-pressure sample containers were filled with a dried ionic liquid and either N 2 O or CO 2 following the procedures outlined in our previous publications [31,32]. VLLE experiments were made with these samples at constant temperatures from about (283 to 310) K using the volumetric method [31,32].…”

“…VLLE experiments were made with these samples at constant temperatures from about (283 to 310) K using the volumetric method [31,32]. The VLLE determined by this method required only mass and volume measurements without any analytical method for molar composition analysis.…”

Solubilities of hydrofluorocarbons in ionic liquids: Experimental and modelling study

“…They used a generic Redlich-Kwong type of cubic EoS [30], with a modified van der Waals-Berthelot mixing rule and critical properties of ILs estimated by Vetere's 4 method [31]. Systems studied by this group include CO 2 in several different Ils [8][9][10][11][12], hydrofluorocarbons and hydrofluoroethers in some Ils [13][14][15][16], ammonia mixtures with Ils [17,18] [23], and H 2 S [24,25]. The authors present most of their results in graphical form and conclude that the model yields a good correlation of the experimental values.…”

Phase equilibria of imidazolium ionic liquids and the refrigerant gas, 1,1,1,2-tetrafluoroethane (R-134a)

“…Shiflett, Yokozeki and coworkers [11][12][13][14][15][16][17][18] have reported the majority of known low- [Tf2N] and R-134a adapted from the data of Ren and Scurto [3] and the vapor pressure of R-134a by Lemmon et al [37]. pressure equilibria data.…”

“…For R-134a, Shiflett and Yokozeki [11] measured and modeled the solubility and diffusivity in seven room-temperature ionic liquids at the low-pressure (<3.5 bar). They also measured vapor-liquid-liquid equilibria of seven hydrofluorocarbons (including R-134a) with 1-butyl-3-methylimidazolium hexafluorophosphate ([BMIm][PF 6 ]) [11,12]. Using a modified Redlich-Kwong equation of state, Shiflett and Yokozeki [15] modeled the low-pressure vapor-liquid equilibrium of R-134a and [EMIm][Tf 2 N].…”