Regulating a sql layered coordination polymer into a rare fsc open framework with naphthalenedisulphonic acid pillar for C₂H₂/CO₂ separation

The removal of carbon dioxide (CO₂) from acetylene (C₂H₂) represents a pivotal industrial process for the production of high-purity C₂H₂. Nevertheless, the separation of C₂H₂ and CO₂ is challenging due to their highly similar molecular sizes and physical properties. In this work, we report a fine regulation of a sql layered coordination polymer (termed NTU-107) into a rare fsc open framework (termed NTU-108) with naphthalenedisulphonic acid pillar for selective C₂H₂ capture from CO₂-contained mixtures. NTU-107 was prepared by the reaction of 4-(1H-imidazol-1-yl)benzoic acid (L1) ligand and Cu²⁺ ion, showing a layered framework with a pore size of 4.2 Å. After inserting 1,5-naphthalenedisulphonic acid between the layers, a new pillar-layered open framework (5.8 Å) with sulphonic acid functional sites was prepared. Single-component gas adsorption experiments and breakthrough experiments demonstrated that NTU-108 with accessible sulphonic acid sites exhibits a high C₂H₂ absorption capacity and dynamic C₂H₂/CO₂ separation performance at room temperature.