Phase Equilibrium Characteristics of CO2 and Ionic Liquids with [FAP]− Anion Used for Absorption-Compression Refrigeration Working Pairs.

The study of the phase equilibrium characteristics of CO₂-ionic liquids (ILs) as new absorption-compression type refrigeration working pairs is of great importance. Three kinds of ILs, i.e., [emim][FAP], [bmim][FAP] and [hmim][FAP], were chosen as potential absorbents. The solubility of CO₂ in these ILs was measured experimentally within 0 to 5.0 MPa at temperatures of 293.15 K to 333.15 K, and the effects of temperature, pressure, IL anion and cation structure and stirring action on CO₂ solubility were also discussed and analyzed. The results showed that the longer alkyl chains in an identical IL family, the alkyl fluoride group in IL anions and the stirring action by a magnetic stirrer had positive effects on the solubility of CO₂. In the three ILs, [hmim][FAP] possessed the best performance for CO₂ absorption; the solubility of CO₂ reached 0.7641 at a pressure of 5 MPa and temperature of 293.15 K, the maximum solubility measured in this work. The CO₂-[hmim][FAP] binary mixture is recommended as a potentially applicable working pair for CO₂ absorption-compression refrigeration systems. [ABSTRACT FROM AUTHOR]