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

Graphical A highly stable, CO 2 facilated transport membrane that can operate at simulated flue gas conditions with temperature up to 90 °C and high humidity is reported. The mobile amine-carriers for CO 2 were stablized within the sulfonated chitosan ion gel membrane. By virtue of carrier-facilitated transport, high CO 2 permeance (as high as 1155 GPU) and ultrahigh CO 2 /N 2 selectivity (above 550) were achieved. Capturing carbon dioxide (CO 2 ) from flue gases is a crucial step towards reducing CO 2 emissions. Among the various carbon capture methods, facilitated transport membranes (FTMs) have emerged as a promising technology for CO 2 capture owing to their high efficiency and low energy consumption in separating CO 2 . 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 CO 2 capture. In this structure, diethylenetriamine (DETA) as a CO 2 -mobile carrier is confined within the SCS gel membrane via electrostatic forces, which can react reversibly with CO 2 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 N 2 . Thus, the prepared membrane exhibits exceptional CO 2 separation capabilities when tested under simulated flue gas conditions with CO 2 permeance of 1155 GPU and an ultra-high CO 2 /N 2 selectivity of above 550. Moreover, the membrane retains a stable separation performance during the 170 h continuous test. The excellent CO 2 separation performance demonstrates the high potential of gel membranes for CO 2 capture from flue gas.