(571a) Nano-Confined Ionic Liquid Membrane for Highly Efficient CO2 Capture from Flue Gas

Membrane technology for CO₂ capture has attracted significant attention because of its great potential for low-energy extraction of CO₂ from flue gas. Among various membranes, facilitated transport membranes, incorporated with active species that can reversibly react with CO₂, have shown their strong capability of highly efficiently separating low-concentration CO₂ from other inert components in flue gas, especially with the presence of water vapor, an inevitable component in flue gas. Amino acid ionic liquids (AAIL) may serve as an ideal active species in facilitated transport membranes, owing to their close-to-zero vapor pressure, excellent thermal stability, and amino acid anions that can reversibly react with CO₂ (especially with the presence of water). In this work, we designed and fabricated a nano-confined AAIL membrane utilizing a novel single-walled carbon nanotube and graphene oxide quantum dot (SWCNT/GOQD) framework. Nano-confined space (3-5 nm), combined with rich functional groups on trapped GOQDs in SWCNT mesh, ensures excellent mechanical stability of infiltrated AAIL. The nano-confined AAIL membrane exhibited excellent CO₂ separation performance, with CO₂ permeance as high as 2,400 GPU and CO₂/N₂ selectivity of >2,000 for simulated NGCC flue gas, achieving >95% CO₂ purity by one-stage separation under membrane stage cut condition (65% CO₂ recovery). Excellent membrane stability over 60-100 h was also demonstrated. We expect this new “nano-confined” platform and utilization of AAILs may expand the family of the facilitated transport membranes and greatly facilitate the development of membrane technology for CO₂ capture from flue gas.