Composite ionic liquid and polymer membranes for gas separation at elevated temperatures

• Published in: Journal of membrane science Vol. 450; pp. 407 - 417
• Main Authors: Liang, Lizhe, Gan, Quan, Nancarrow, Paul
• Format: Journal Article
• Language: English
• Published: Amsterdam Elsevier B.V 01.01.2014; Elsevier
• Subjects: Applied sciences; Carbon dioxide; Chemistry; Colloidal state and disperse state; Composite ionic liquid membrane; Exact sciences and technology; Exchange resins and membranes; Forms of application and semi-finished materials; Gas separation; General and physical chemistry; High temperature; Ionic liquid; Ionic liquids; Membranes; Permeability; Polybenzimidazole; Polybenzimidazoles; Polyimide; Polymer industry, paints, wood; Selectivity; Technology of polymers; Polyimide; Composite ionic liquid membrane; Gas separation; Polybenzimidazole; Ionic liquid; Membrane separation; Polymeric membrane; Composite material
• ISSN: 0376-7388; 1873-3123
• DOI: 10.1016/j.memsci.2013.09.033

In recent years, the utilization of ionic liquids supported on porous polymer membranes has been demonstrated to enhance gas separation performance by improving both permeability and selectivity for several industrially-relevant gas mixtures. However, the use of such supported ionic liquid membranes (SILMs) is normally not feasible at elevated process temperatures due to the resulting decrease in ionic liquid viscosity, which can lead to increased loss of ionic liquid from the membrane support during operation. In addition, many of the polymer membranes typically used in SILMs exhibit relatively poor mechanical and thermal stabilities at high temperatures. To overcome these problems associated with SILMs, thermally-stable composite ionic liquid and polymer membranes (CILPMs) have been fabricated in this study, thus exploiting the beneficial properties of ionic liquids for gas separation at elevated temperatures. Poly(pyromellitimide-co-4,4′-oxydianiline) (PMDA-ODA PI) and polybenzimidazole (PBI) in combination with the ionic liquid, [C4mim][NTf2] were used to fabricate the CILPMs. A measurement rig was designed and built to determine permeabilities and selectivities of the CILPMs for H2, N2, CO, CO2 and CH4 over a range of pressures and temperatures. The fabricated CILPMs were shown to maintain excellent mechanical and thermal stability over a wide range of processing conditions. Temperature was shown to greatly affect both permeability and selectivity of the membranes, whilst pressure had less influence. The incorporation of [C4mim][NTf2] into the membranes was found to significantly increase CO2 permeation and, therefore, it is anticipated that these CILPMs hold significant potential for CO2 separation applications. •Thermally-stable composite ionic liquid/polymer membranes (CILPMs) were fabricated.•Excellent mechanical and thermal stability over a wide range of conditions.•Measurement rig designed and built to determine gas permeabilities/selectivities.•[C4mim][NTf2] in membranes found to significantly increase CO2 permeation.•These CILPMs hold significant potential for CO2 separation applications.