The increasing awareness of the environmental impact of fluorinated gases (Fgases) used in refrigeration is instigating the development of technologies to recover and recycle them. With this goal in mind, single-component absorption equilibrium isotherms at 303.15 K of F-gases in different ionic liquids (ILs) were determined using a gravimetric method. The selected F-gases are the most used in domestic refrigeration (R-32: difluoromethane, R-125: pentafluoroethane, and R-134a: 1,1,1,2-tetrafluoroethane). The results show that ILs containing a fluorinated alkyl side chain with four carbon atoms, i.e., fluorinated ionic liquids (FILs), have higher gas absorption capacity than conventional fluoro-containing ILs. All studied ILs showed ideal selectivity towards R-134a. Conventional fluoro-containing ILs showed better selectivities for the separation of the binary mixtures R-134a/R-125 and R-32/R-125 and FILs showed better selectivities for the R-134a/R-32 mixture. These results provide fundamental knowledge of the behavior of these new alternative solvents and key information for their application in the separation of F-gases mixtures of commercial refrigerants.

The environmental impact of fluorinated gases (F-gases) necessitates the development of green technologies to mitigate them. Fluorinated ionic liquids (FIL/ILs) emerged as an alternative absorbent due to their unique and exceptional properties. In this work, a COSMO-based/ Aspen Plus methodology was used to evaluate the performance of FIL/ILs as absorbents in the process scale of two F-gases: 1,1,1,2-tetrafluoroethane (R-134a) and difluoromethane (R-32). Results of the absorption column in equilibrium mode revealed that the behavior of FIL/ILs is similar under the same conditions, reaching higher efficiencies in the case of absorbing R-134a at a high F-gas partial pressure. Rate-based calculations in packing column demonstrated a kinetic control with highly viscous FIL/ILs, revealing higher performance differences between FIL/IL absorbents. The regeneration stage was also evaluated in near-industrial conditions. Operating conditions of the absorption column were optimized with a column of height 10 m and diameter ranging from 1.1 to 1.2 m at 10 bar total pressure, reaching 90% F gas recovery with an L/G range of 6−10. Finally, preliminary economic analysis revealed operating costs to recover 90% of F-gas of 70 $/ton (R-134a) and 130 $/ton (R-32) with the FIL/IL that revealed the best behavior, 1-ethyl-3-methylimidazolium triflate.

Background The increasing awareness of the release of fluorinated gases (F‐gases) into the atmosphere is instigating the development of techniques to capture them from refrigerants. In this work, the adsorption of difluoromethane (R‐32), pentafluoroethane (R‐125), and 1,1,1,2‐tetrafluoroethane (R‐134a) on four different activated carbons (ACs) is studied. Additionally, the selectivity of the ACs for the components of commercial refrigerants, R‐410A and R‐407F, is evaluated. Results The estimation of the density of the adsorbed phase as a function of temperature allows the experimental fractional loading of each F‐gas on any of the ACs to be correlated as a temperature‐independent function of its reduced pressure, which is described by Tóth or dual‐site Langmuir equations or as an exponential function of the adsorption potential under the framework of the Adsorption Potential theory (APT). It is shown that the APT can be generalized with excellent accuracy to the systems studied if an adsorbate‐dependent affinity coefficient is used as a shifting factor to bring the characteristic curves of all F‐gases into a single one for each AC. R‐32 is the F‐gas most adsorbed by all adsorbents, followed by R‐134a, and by R‐125. All ACs are selective for R‐125 in R‐410A commercial refrigerants, especially at lower pressures. Additionally, all ACs are selective for R‐125 and R‐134a over R‐32 in R407‐F commercial refrigerant. Conclusion The utilization of ACs for adsorption of the three most used F‐gases is promising. By selecting ACs with different porous characteristics, it is possible to evaluate their influence on the selectivity for the components of different commercial refrigerants. © 2020 Society of Chemical Industry