Hydrofluorocarbon refrigerants are being phased out over the next two decades due to their high global warming potential. To separate and recycle refrigerants that form azeotropic mixtures, current distillation methods are inadequate and a new technology is required. Extractive distillation using an ionic liquid as the entrainer offers a solution. Vapor liquid equilibria data for refrigerants difluoromethane (HFC-32), chlorodifluoromethane (HCFC-22), pentafluoroethane (HFC-125), 1,1,1-trifluoroethane (HFC-143a), and 1,1,1,2-tetrafluoroethane (HFC-134a) in ionic liquids 1-ethyl-3-methylimidazolium bis­(trifluoromethylsulfonyl)­imide ([C2C1im]­[Tf2N]) and 1-butyl-3-methylimidazolium hexafluorophosphate ([C4C1im]­[PF6]) were fit with the Peng–Robinson equation of state to simulate the separation of four azeotropic refrigerant mixtures (R-404A, R-407C, R-410A, and R-410A + HCFC-22) and to develop rate-based and equilibrium models in ASPEN Plus. Process flow diagrams were developed and optimized based on a set of physical and chemical constraints. The goal was to optimize the parameters to achieve refrigerant grade (>99.5 wt %) purity. The ionic liquids were found to be effective entrainers for separating refrigerant mixtures.

Hydrofluorocarbon refrigerants are being phased out over the next two decades due to concerns about high global warming potential. In order to separate refrigerant mixtures that form azeotropes, new technologies will be required. Currently, fractional distillation is unable to efficiently separate azeotropic refrigerant mixtures. Extractive distillation using an ionic liquid as the entrainer offers a solution. Vapor–liquid equilibria data for refrigerants difluoromethane (HFC-32), pentafluoroethane (HFC-125), 1,1,1,2-tetrafluoroethane (HFC-134a), 1,1,1-trifluoroethane (HFC-143a), chlorodifluoromethane (HCFC-22), propane (HC-290), and isobutane (HC-600a) and ionic liquid 1-butyl-3-methylimidazolium hexafluorophosphate ([C4C1im]­[PF6]) was regressed using the Peng–Robinson equation of state with the van der Waals 1-parameter mixing rule and Boston–Mathias nonideal correction. Process flow diagrams using ASPEN simulations were prepared for demonstrating how multicomponent mixtures of these refrigerants can be separated. Opportunities for measuring and modeling the solubility of new refrigerants in ionic liquids are discussed, and challenges remain for effectively separating some azeotropic refrigerant mixtures containing hydrofluorocarbons and hydrocarbons.

CPE616 is the first course in which KU chemical engineering students apply their knowledge from junior-level core chemical engineering courses to data collected in a lab. The course is taught by three professors (one for each of the three experiments), a lab manager to supervise the course, and a lab assistant to make sure that the day-to-day operation of the lab runs smoothly. Students rotate through three experiments in CPE616:Vapor-Liquid Equilibrium (VLE), Fluid Mechanics (FLU), and Kinetics (KIN). The VLE experiment uses a four-