Heteroatom-Engineered Covalent Organic Frameworks Break the CO 2 Separation Trade-Off in Mixed Matrix Membranes

作者：Tsukasa Irie, Liting Yu, Sourav Ghosh, Mika Nozaki, Kohki Sasaki, Tokuhisa Kawawaki, Ranjit Thapa, Yu Zhao, Saikat Das, Zixi Kang, Yuichi Negishi · 发表于：Journal of the American Chemical Society · 年份：2026 · DOI：10.1021/jacs.5c23169 · 被引用次数：2 · 研究领域：Covalent Organic Framework Applications、Membrane Separation and Gas Transport、Carbon dioxide utilization in catalysis

High Resolution Image Download MS PowerPoint Slide Breaking the long-standing permeability–selectivity trade-off remains a central challenge in membrane-based carbon dioxide separations. Here we report a heteroatom-engineering strategy that leverages structurally precise covalent organic frameworks (COFs) to transcend this limitation in mixed matrix membranes (MMMs). Two isostructural, π-conjugated two-dimensional COFs, TUS-621 and TUS-622, were rationally designed through symmetry-guided reticulation of a hexatopic triphenylene node with oxygen- and sulfur-containing diamine linkers, respectively, enabling systematic modulation of pore surface chemistry without altering topology. When incorporated into a Pebax polymer matrix, these COFs function as CO 2 -philic, molecularly defined transport domains that synergistically couple preferential CO 2 sorption with ordered and fast diffusion channels. The optimized TUS-621/Pebax-10% membrane exhibits a CO 2 permeability of 433 Barrer with a CO 2 /CH 4 selectivity of 55.3 under mixed-gas conditions, decisively surpassing the 2008 Robeson upper bound for CO 2 /CH 4 separation while simultaneously achieving high CO 2 /H 2 separation performance (CO 2 permeability of 407 Barrer and selectivity of 25.2). Comprehensive pressure- and temperature-dependent permeation studies reveal that selectivity remains remarkably stable over 2–10 bar and 25–100 °C, underscoring the robustness of the COF-enabled transport pathways. Long-term operation o...