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

Abstract

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.

Keywords

• ionic liquids
• polymers of intrinsic microporosity
• CO₂
• gas separation
• supported ionic liquids membranes
• carbon capture and storage