Heterogeneous Facilitated Transport Membrane via Ionic Liquid‐Mediated Interfacial Polymerization for CO ₂ Separation

Abstract Polyamide (PA) membranes, prepared by facile and scalable interfacial polymerization (IP), have the potential to serve as candidates for large‐scale CO 2 capture from flue gases in power plants. However, current PA‐based membranes exhibited poor CO 2 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 CO 2 capture. During the IP process, IL regulated and modified the gas transport channels within the PA matrix to accommodate the mobile CO 2 carrier, namely IL itself. Owing to the negatively charged PA matrix and facilitated transport feature, PA/IL (PAIL) membranes exhibited superior and stable CO 2 permeance up to 1 050 GPU and CO 2 /N 2 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 CO 2 permeance and capable of enriching CO 2 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.