Enhanced selectivity and stability for CO₂ capture through amine-functionalized COFs-based mixed matrix membranes

How to improve the selectivity and stability while ensure the membrane permeability is a challenge of mixed matrix membranes (MMMs) for gas separation applications. We herein report an amine-functionalized COFs-based mixed-matrix membranes (MMMs) for CO₂/N₂ separation, specifically COF-300-Amide/Pebax2533. This approach endeavors to concurrently enhance the selectivity of CO₂/N₂ and stability while maintain the high permeability of CO₂. The natural pore structure of amide-linked COFs significantly enhances the selectivity for CO₂/N₂ separation, achieving a high permeability of 697.3 Barrer and superior CO₂/N₂ selectivity up to 51.7. Furthermore, the highly crystalline nature and strong amide bonds of the amide-linked COFs greatly enhance membrane stability, as evidenced by an impressive anti-decomposition temperature of 390.2 °C and sustained performance over 28 days. The underlying interaction mechanisms of CO₂ adsorption and its diffusion mechanism of the COFs, along with their interfacial compatibility with the Pebax2533 matrix, were comprehensively quantified using GCMC, dcTSTs, and MD simulations. This pioneering study demonstrates that amide-linked COF-based MMMs possess remarkable potential for industrial CO₂/N₂ separation applications, offering an innovative solution that combines high efficiency with long-term operational stability.