Supported Ionic Liquid Membrane with Highly‐permeable Polyamide Armor by In Situ Interfacial Polymerization for Durable CO2 Separation

Abstract Supported ionic liquid membranes (SILMs), owing to their capacities in harnessing physicochemical properties of ionic liquid for exceptional CO 2 solubility, have emerged as a promising platform for CO 2 extraction. Despite great achievements, existing SILMs suffer from poor structural and performance stability under high‐pressure or long‐term operations, significantly limiting their applications. Herein, a one‐step and in situ interfacial polymerization strategy is proposed to elaborate a thin, mechanically‐robust, and highly‐permeable polyamide armor on the SILMs to effectively protect ionic liquid within porous supports, allowing for intensifying the overall stability of SILMs without compromising CO 2 separation performance. The armored SILMs have a profound increase of breakthrough pressure by 105% compared to conventional counterparts without armor, and display high and stable operating pressure exceeding that of most SILMs previously reported. It is further demonstrated that the armored SILMs exhibit ultrahigh ideal CO 2 /N 2 selectivity of about 200 and excellent CO 2 permeation of 78 barrers upon over 150 h operation, as opposed to the full failure of CO 2 separation performance within 36 h using conventional SILMs. The design concept of armor provides a flexible and additional dimension in developing high‐performance and durable SILMs, pushing the practical application of ionic liquids in separation processes.