Heterogeneous Facilitated Transport Membrane via Ionic Liquid-Mediated Interfacial Polymerization for CO₂ Separation

Polyamide (PA) membranes, prepared by facile and scalable interfacial polymerization (IP), have the potential to serve as candidates for large-scale CO₂ capture from flue gases in power plants. However, current PA-based membranes exhibited poor CO₂ separation performance, restricting their large-scale uses. Herein an ionic liquid (IL)-mediated IP process is developed for fabricating novel PA-based heterogeneous facilitated transport membranes (HFTMs) for efficient CO₂ capture. During the IP process, IL regulated and modified the gas transport channels within the PA matrix to accommodate the mobile CO₂ carrier, namely IL itself. Owing to the negatively charged PA matrix and facilitated transport feature, PA/IL (PAIL) membranes exhibited superior and stable CO₂ permeance up to 1 050 GPU and CO₂/N₂ selectivity up to 300 under simulated flue gas separation conditions. The selectivity of these PAIL membranes is one order of magnitude higher than reported membranes with similar CO₂ permeance and capable of enriching CO₂ from 15% to 97% in one step. Given the one-step, facile membrane preparation via IP technology, this work may open a new field of synthesizing ultrathin, highly selective HFTMs in a practical and scalable way for highly efficient gas separation applications.