Scalable and Green Mechanochemical Synthesis of (dtz)CALF-20 for Enhanced Low-Concentration CO ₂ Capture

CO 2 capture is a critical technology for mitigating global climate change. This study systematically investigates the low-concentration CO 2 capture performance of (dtz)CALF-20, constructed by zinc, oxalic acid, and diaminotriazole, specifically designed for CO 2 capture from confined spaces. By constructing specific adsorption sites via nitrogen-rich diaminotriazole ligands, the material achieves efficient capture of low-concentration CO 2 . To overcome the limitations of (dtz)CALF-20-hydrotherm from conventional hydrothermal synthesis, which relies heavily on organic solvents and is energy-intensive, this work introduces an innovative (dtz)CALF-20-mechchem synthesized by a room-temperature mechanochemical ball-milling method. The green approach not only facilitates scalable production but also enables the rapid preparation of (dtz)CALF-20-mechchem, achieving a high space-time yield (STY) of 4600 kg·m –3 ·d –1 and a yield of 98%, which are approximately 28 times and 1.3 times higher than those of the traditional (dtz)CALF-20-hydrotherm. It is shown that (dtz)CALF-20-mechchem exhibits excellent adsorption performance at 5000 ppm of CO 2, achieving an adsorption capacity of 1.40 mmol/g, representing a 21.7% enhancement when compared with that of (dtz)CALF-20-hydrotherm. After being shaped into spherical pellets with sodium alginate, the material effectively reduces the bed pressure drop, making it more suitable for industrial applications, while retaining 95% of its original CO 2 adsorption performance. Dynamic breakthrough experiments reveal an exceptional CO 2 /N 2 selectivity of 936, which means an approximately 11-fold enhancement over that of (dtz)CALF-20-hydrotherm. This work presents a promising strategy for the green and scalable production of high-performance metal–organic frameworks (MOFs) adsorbents, significantly advancing their practical application.