Ionic Liquids-Polymer of Intrinsic Microporosity (PIMs) Blend Membranes for CO₂ Separation

Membranes with high CO₂ solubility are essential for developing a separation technology with low carbon footprint. To this end, physical blend membranes of [BMIM][Ac] and [BMIM][Succ] as Ionic Liquids (ILs) and PIM-1 as the polymer were prepared trying to combine the high permeability properties of PIM-1 with the high CO₂ solubility of the chosen ILs. Membranes with a PIM-1/[BMIM][Ac] 4/1 ratio nearly double their CO₂ solubility at 0.8 bar (0.86 cm³ (STP)/cm³ cmHg), while other ratios still maintain similar solubilities to PIM-1 (0.47 cm³ (STP)/cm³ cmHg). Moreover, CO₂ permeability of PIM-1/[BMIM][Ac] blended membranes were between 1050 and 2090 Barrer for 2/1 and 10/1 ratio, lower than PIM-1 membrane, but still highly permeable. The here presented self-standing and mechanically resistant blend membranes have yet a lower permeability compared to PIM-1 yet an improved CO₂ solubility, which eventually will translate in higher CO₂/N₂ selectivity. These promising preliminary results will allow us to select and optimize the best performing PIM-1/ILs blends to develop outstanding membranes for an improved gas separation technology.