Composite poly(ionic liquid)-ionic liquid membranes containing copper (I) chloride (CuCl) have been successfully fabricated via photopolymerization of an IL monomer, 1-vinyl-3-butylimidazolium bistriflimide ([C4vim][Tf2N]), in the presence of CuCl and a non-polymerizable IL, 1-butyl-3-methylimidazolium chloride ([C4mim][Cl]), forming the chlorocuprate anion ([CuCl2]-) in situ. The influence of the metal salt content on the gas separation performance of the composite membranes was assessed. Results showed that increasing the content of non-polymerizable IL enhanced the permeabilities of CO2, H2, N2 and CO relative to those obtained in the pristine poly([C4vim][Tf2N]); whereas the addition of CuCl induced a general reduction of gas diffusivity. On the whole, an enhancement of both gas permeability and ideal gas pair selectivity were observed for CO2/N2 and H2/N2 separations in the Cu-containing composite membranes with respect to the neat poly([C4vim][Tf2N]).Financial support from the Spanish Ministry of Economy and Competitiveness (MINECO) under projects CTQ2012-31639 at the Universidad de Cantabria is gratefully acknowledged. Additional support from the American Chemical Society – Petroleum Research Fund (ACS-PRF 52190-DNI9) is acknowledged

The restrictions imposed to the production of high-global warming potential refrigerant gases have boosted the search of novel separation processes for the selective recovery of hydrofluorocarbons (HFCs) and hydrofluoroolefins (HFO) from exhausted refrigerant mixtures. Membrane materials functionalized with ionic liquids can offer an effective techno-economical response to the challenging separation of HFC/HFO blends. In this work, we provide for the first time a thorough characterization of the gas solubility and permeation properties of three of the most relevant compounds for the future of the refrigeration and air conditioning sector, that is, difluoromethane (HFC-R32), 1,1,1,2-tetrafluoroethane (HFC-R134a), and 2,3,3,3-tetrafluoropropene (HFO-R1234yf), through composite ionic liquid–polymer membranes (CILPMs) that were prepared combining the Pebax 1657 copolymer with several ILs, [C₂mim][SCN], [C₂mim][BF₄], [C₂mim][OTf], and [C₂mim][Tf₂N], varying the IL content in the range of 20–60 wt %. The CILPMs with the best separation performance and mechanical stability against feed pressure were those with 40 wt % of [C₂mim][BF₄] and [C₂mim][SCN]. For the 40 wt % [C₂mim][BF₄] CILPM, the addition of IL promoted the permeability of the smallest molecules R32 and R134a and reduced the permeability of the largest molecule R1234yf, which resulted in 120 and 75% selectivity enhancement relative to that of the pristine polymer for R32/R1234yf and R134a/R1234yf mixtures, respectively. Finally, this CILPM was stable in the separation of two commercial HFC/HFO refrigerant blends (R513A and R454B) over a wide pressure range (up to 12 bar). These results indicate that CILPMs can be used for separating azeotropic and near-azeotropic exhausted HFC/HFO mixtures, which could stimulate the recovery and reuse of their components and thus avoid their emissions and pull down the demand for virgin refrigerants.