Poly(ethylene oxide)-Based Copolymer-IL Composite Membranes for CO 2 Separation

• Published in: Membranes (Basel) Vol. 13; no. 1
• Main Authors: Vroulias, Dionysios, Staurianou, Eirini, Ioannides, Theophilos, Deimede, Valadoula
• Format: Journal Article
• Language: English
• Published: Switzerland 25.12.2022
• Subjects: polymer-IL composite membranes; CO2 permeability; CO2/H2 selectivity; PEO-based copolymers; water vapor permeability; CO2/CH4 selectivity
• ISSN: 2077-0375; 2077-0375

Poly(ethylene oxide) (PEO)-based copolymers are at the forefront of advanced membrane materials for selective CO separation. In this work, free-standing composite membranes were prepared by blending imidazolium-based ionic liquids (ILs) having different structural characteristics with a PEO-based copolymer previously developed by our group, targeting CO permeability improvement and effective CO /gas separation. The effect of IL loading (30 and 40 wt%), alkyl chain length of the imidazolium cation (ethyl- and hexyl- chain) and the nature of the anion (TFSI , C(CN) ) on physicochemical and gas transport properties were studied. Among all composite membranes, PEO-based copolymer with 40 wt% IL3-[HMIM][TFSI] containing the longer alkyl chain of the cation and TFSI as the anion exhibited the highest CO permeability of 46.1 Barrer and ideal CO /H and CO /CH selectivities of 5.6 and 39.0, respectively, at 30 °C. In addition, almost all composite membranes surpassed the upper bound limit for CO /H separation. The above membrane showed the highest water vapor permeability value of 50,000 Barrer under both wet and dry conditions and a corresponding H O/CO ideal selectivity value of 1080; values that are comparable with those reported for other highly water-selective PEO-based polymers. These results suggest the potential application of this membrane in hydrogen purification and dehydration of CO gas streams.