Ion-gated carbon molecular sieve gas separation membranes

• Published in: Journal of membrane science 2020-06, Vol.604 (C), p.118013, Article 118013
• Main Authors: Guo, Wei, Mahurin, Shannon M., Wang, Song, Meyer, Harry M., Luo, Huimin, Hu, Xunxiang, Jiang, De-en, Dai, Sheng
• Format: Article
• Language: English
• Subjects: Carbon molecular sieve; Gas separation; INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CHEMISTRY; Ionic liquid; Molecular dynamic simulation; Robeson limit
• ISSN: 0376-7388; 1873-3123
• DOI: 10.1016/j.memsci.2020.118013

Membrane technology lies at the heart of many industrial gas separation processes and applications. Molecular sieving membranes that break the Robeson limit are desirable for energy-efficient gas separation. Herein, we report a facile strategy of directly integrating ionic liquids (ILs) into porous membranes. Particularly, the ILs form an ultra-thin layer on the carbon molecular sieve (CMS) membranes rather than penetrating into the pores, acting as a smart gate for gas entry to boost the selectivity. The hybrid membrane exhibits CO2 permeability >600 barrer and enhanced CO2/N2 selectivity >50, which surpasses the Robeson limit and shows potential in CO2/N2 separation process. Molecular dynamics simulations confirm the gating effect of the IL layer of molecular thickness. This work demonstrates a universal strategy to improve CMS membrane performance by creating an IL-membrane interface and tuning the ion-pore interaction. A single layer of ionic liquids atop microporous carbon membranes can boost CO2 separation performance that surpass Robeson limit. [Display omitted] •The corporative combination ionic liquids and porous membranes are used for a hybrid membrane.•The hybrid membrane has excellent CO2/N2 separation performance that surpasses the Robeson limit.•Ionic liquids with molecular thickness are verified to be a smart gate for sieving CO2 from N2.•The strategy is expected to be useful for optimizing other porous materials.