Immobilization of H ₂ O in Diffusion Channel of Metal–Organic Frameworks for Long‐Term CO ₂ Capture from Humid Flue Gas

Abstract

Abstract Utilizing physisorption for CO 2 capture in humid flue gas presents challenges, with H 2 O molecules either damaging the adsorbent or competing with CO 2 for adsorption, compromising long‐term stability. Herein, a counter‐intuitive strategy is proposed to address this issue by immobilizing H 2 O into metal–organic framework (TYUT‐ATZ, TYUT = Taiyuan University of Technology, ATZ = 3‐amino‐1,2,4‐triazole) as binding sites for CO 2 capture from humid airflow. Through tailoring the ‐NH 2 group numbers and pore sizes creates ingenious H 2 O sites, preserving CO 2 adsorption space and enhancing CO 2 adsorption interactions in 1D channels. The well‐constructed TYUT‐ATZ‐β demonstrates a high CO 2 adsorption capacity (62.7 cm 3 cm −3 ) at 0.15 bar and outstanding CO 2 /N 2 (15/85) selectivity (2031) at 298 K, while also exhibits the highest CO 2 /H 2 O uptake ratio in humid flue gas due to its excellent water stability and unique H 2 O site. Consequently, it shows top‐performing CO 2 enrichment ability with easy regeneration in long‐term separation experiments (over 100 cycles) under high‐humidity (75% RH). Gas adsorption isotherms, single‐crystal analysis, selectivity calculations, and contrastive breakthrough experiments comprehensively validate this artful H 2 O immobilization strategy in MOFs for efficient CO 2 capture in humid flue gas, satisfying the application requirements of high selectivity, rapid regeneration, and long‐term stability.