Preparation and\nTransmembrane Transport Mechanism\nof Liquid-Catched Supported Membranes with High CO<sub>2</sub> Separation\nPerformance

CO<sub>2</sub> capture is essential for addressing dual-carbon\nstrategies and achieving carbon neutrality. Membrane separation is\nfavored for CO<sub>2</sub> separation due to its high efficiency,\nlow energy consumption, and operational convenience. Combining supported\nliquid membrane technology with ionic liquids (ILs) enables continuous\nCO<sub>2</sub> separation from flue gas without requiring regeneration,\nsimplifying processes, and reducing steps compared to pure IL absorption\nor adsorption methods. However, supported IL membranes suffer from\nliquid leakage. This study proposes a novel mechanism for CO<sub>2</sub> capture using liquid-catched supported membranes (LCSMs). The LCSM\nwas formed by adding a liquid-locking polymer layer to a porous support\nmembrane. This study investigates the CO<sub>2</sub> separation performance\nof LCSMs from the perspectives of material optimization and operational\nconditions. Sodium polyacrylate was selected as the liquid-locking\npolymer material based on molecular simulations. Experiments were\nconducted to investigate the effects of the support membrane type,\nliquid type, and liquid concentration on CO<sub>2</sub> separation\nby LCSMs. Further experiments examined the influence of temperature,\npressure, liquid concentration, and gas source composition on the\nseparation performance of LCSMs. The optimal conditions for membrane\nfabrication and operation were determined. In addition, the transmembrane\ntransport mechanism of CO<sub>2</sub> separation using LCSMs was studied\nusing molecular dynamics simulations, modeling analyses, and calculations.\nThe simple solution-diffusion mechanism could not accurately describe\nthe CO<sub>2</sub> transmembrane transport behavior. A modified solution-ionization-diffusion\nmechanism was proposed to elucidate the CO<sub>2</sub> transmembrane\ntransport mechanism in LCSMs, showing good agreement with experimental\nresults of CO<sub>2</sub>/N<sub>2</sub> separation. Finally, a process\nfor CO<sub>2</sub> separation from the flue gas was developed. Preliminary\ncalculations indicated that the capture energy consumption could be\nreduced to less than 2 GJ/tCO<sub>2</sub>, significantly lower than\ntraditional absorption methods, with broader applicability and reduced\nfootprint. This process is simpler, continuous, and less expensive.\nThese results indicate that LCSMs are promising and novel methods\nfor CO<sub>2</sub> capture, offering an effective and economical solution\nfor industrial applications.