Exceptional SF <sub>6</sub> /N <sub>2</sub> Separation of Metal–Organic Frameworks by Overcoming the Capacity‐Selectivity Trade‐Off via Ligand Engineering
Hong‐Xiang Nie, Hong‐Wei Chen, Hongliang Huang, Libo Li, Jiandong Pang, Ze Chang, Xian‐He Bu
Abstract
Abstract The effective capture of sulfur hexafluoride (SF 6 ) is crucial from both economic and environmental viewpoints. However, the investigation of low‐energy and sustainable methods for separating SF 6 from the SF 6 /N 2 mixture remains challenging. Herein, a ligand engineering strategy is employed to optimize the metal–organic framework (MOF) adsorbent for effective separation of SF 6 and N 2 . By utilizing the isoreticular chemistry with structurally similar tetracarboxylic acid ligands, a series of Al‐MOFs is constructed, enabling systematic and precise pore size optimization and surface functionalization to enhance SF 6 binding affinity. Remarkably, the compound 4 , based on 2,3,5,6‐tetrakis(4‐carboxyphenyl)pyrazine ligand, is screened to exhibit both high SF 6 uptake at low pressure (55 cm 3 g −1 at 10 kPa and 84 cm 3 g −1 at 100 kPa, 298 K) and high SF 6 /N 2 selectivity of (512 for 10/90 mixture), which surpasses most reported MOFs. Furthermore, breakthrough experiments demonstrate that these Al‐MOFs can recover high‐purity SF 6 from low‐concentration (10%) SF 6 /N 2 mixture under high‐humidity conditions, with exceptional stability over multiple cycles. Theoretical calculations reveal the supramolecular interactions between SF 6 and the framework, elucidating the mechanism behind the superior performance of these materials. This work highlights the potential of pore engineering in MOFs to overcome the selectivity‐uptake trade‐off, offering a sustainable solution for SF 6 management.