CO₂ separation membranes using ion gels by self-assembly of a triblock copolymer in ionic liquids

• Published in: Chemical engineering journal (Lausanne, Switzerland : 1996) Switzerland : 1996), 2011-08, Vol.172 (1), p.237-242
• Main Authors: Yoon, Il-Nyoung, Yoo, Soondong, Park, Soung-Jin, Won, Jongok
• Format: Article
• Language: English
• Subjects: anions; Applied sciences; Chemical engineering; differential scanning calorimetry; Exact sciences and technology; gels; ionic liquids; liquid membranes; microstructure; nylon; X-ray diffraction
• ISSN: 1385-8947; 1873-3212
• DOI: 10.1016/j.cej.2011.05.096

CO₂ separation ion gel membranes with compatible permselectivity for supported ionic liquid membranes (SILMs) and good mechanical stability were developed using a triblock copolymer that self-assembles in CO₂-selective ionic liquids (ILs). Three ion gels with 1-n-hexyl-3-methylimidazolium ([hmim]) cation base, each containing different anions ([Tf₂N⁻], [BF₄ ⁻], and [PF₆ ⁻]) and a small amount of poly(styrene-block-ethylene oxide-block-styrene) (SEOS) triblock copolymer were prepared and characterized using differential scanning calorimetry and wide-angle X-ray diffraction analysis. Mechanically stable composite membranes made with three different ion gels were prepared by the self-assembly of IL/SEOS on the surface of the nylon support membrane and characterized by the measurement of their CO₂ separation performance. The ideal CO₂/CH₄ separation factors were 9.0, 9.5 and 9.9 for the ion gel membranes containing [hmim][Tf₂N], [hmim][BF₄] and [hmim][PF₆], respectively. These values are consistent with or higher than those of SILMs due to the microstructure formation inside the ion gels.