I&EC Research September 2023

Abstract

The separation of azeotropic refrigerant mixtures is an important issue due to recent legislation requiring regulation and phase down. The ability to separate and recycle refrigerants is needed, as many refrigerants will be at end-of-life over the next couple of decades. Polymeric membranes provide the ability to separate refrigerant mixtures based on differences in solubility and diffusivity. The current study investigates the use of a copolymer of perfluoro(2,2-dimethyl-1,3-dioxole) (PDD) and vinyl acetate (VA) for refrigerant separation. The permeability, solubility, and diffusivity of HFC-32 (CH2F2), HFC-125 (CHF2CF3), HFC-134a (CF3CH2F), HFO-1234yf (CH2═CFCF3), and HCFC-22 (CHClF2) were measured in PDD-co-VA at 308.15, 323.15, 348.15, and 373.15 K. Arrhenius relationships were used to obtain the activation energy of permeation for each refrigerant. Arrhenius solubility and diffusivity relationships were applied to HFC-32 and HFC-125 to obtain the activation energy of diffusion and heat of sorption. Results indicate that selectivity decreases as the temperature increases. A high selectivity of 35 can be obtained for HFC-32/HFC-125 while maintaining a high permeability at 308.15 K. High selectivities of HFC-32/HFC-125, HFC-32/HFO-1234yf, HFC-32/HFC-134a, and HCFC-22/HFC-125 indicate the commercial potential of this polymer in the separation of refrigerant mixtures.

Citation

Ind. Eng. Chem. Res. 2023, 62, 37, 15148–15156