Sulfonated Chitosan Gel Membrane with Confined Amine Carriers for Stable and Efficient Carbon Dioxide Capture

Capturing carbon dioxide (CO₂) from flue gases is a crucial step towards reducing CO₂ emissions. Among the various carbon capture methods, facilitated transport membranes (FTMs) have emerged as a promising technology for CO₂ capture owing to their high efficiency and low energy consumption in separating CO₂. However, FTMs still face the challenge of losing mobile carriers due to weak interaction between the carriers and membrane matrix. Herein, we report a sulfonated chitosan (SCS) gel membrane with confined amine carriers for effective CO₂ capture. In this structure, diethylenetriamine (DETA) as a CO₂‐mobile carrier is confined within the SCS gel membrane via electrostatic forces, which can react reversibly with CO₂ and thus greatly facilitate its transport. The SCS ion gel membrane allows for the fast diffusion of amine carriers within it while blocking the diffusion of nonreactive gases, like N₂. Thus, the prepared membrane exhibits exceptional CO₂ separation capabilities when tested under simulated flue gas conditions with CO₂ permeance of 1155 GPU and an ultra‐high CO₂/N₂ selectivity of above 550. Moreover, the membrane retains a stable separation performance during the 170 h continuous test. The excellent CO₂ separation performance demonstrates the high potential of gel membranes for CO₂ capture from flue gas.