Pentafluoroethane Dehydration with Ionic Liquids

Ionic liquids (ILs) were proposed as promising separating agents for the hydrofluorocarbons (HFCs) pentafluoroethane (R125) dehydration. Taking into account the H2O solubility and selectivity of H2O to R125 in a variety of IL candidates, we determined the hydrophilic [EMIM]­[BF4] as a satisfactory absorbent. Besides, some theoretical insights into separation mechanism at the molecular level were explored by means of the combination of COSMO-RS model and quantum chemistry calculation. The gas–liquid equilibrium (GLE) data for the binary R125-[EMIM]­[BF4] and ternary R125-H2O-[EMIM]­[BF4] systems were measured, and the experimental data were compared with the predicted results by COSMO-RS model. The R125 dehydration experiment with IL was carried out. Furthermore, the continuous processes for R125 dehydration with [EMIM]­[BF4] and the conventional benchmark solvent tetraethylene glycol (TeEG) as absorbents were simulated and optimized with the rigorous equilibrium (EQ) stage model, in which COSMO-SAC model was selected. It was confirmed that the R125 gas dehydration with IL presented in this work is a typical process intensification technology.