Novel Pillared-Layer-like\nMetal–Organic Frameworks\nwith Quadrilateral Channels for Efficient Separation of C₂H₂ from C₂H₂/CO₂ and\nC₂H₂/C₂H₄ Mixtures

Abstract

The selective separation of C₂H₂ from C₂H₂/CO₂ and C₂H₂/C₂H₄ is crucial but remains incredibly\nchallenging\ndue to their extremely similar physical characteristics and nearly\nequivalent molecular kinetic diameters. Here, four novel pillared-layer-like\nmetal–organic frameworks (MOFs) with quadrilateral channels,\nSNNU-283–286, which consist of a unique two-dimensional wave\nlayer and carboxylic acid ligands as columns, are successfully synthesized\nvia a facile solvothermal process. Interestingly, with the decrease\nof the bent angle between two −COOH groups in ligands, the\ndistortion of the quadrilateral channel increases, and the two-dimensional\nwave layer becomes more curving. The optimized SNNU-285 with appropriate\nstructural distortion exhibits remarkably high C₂H₂ adsorption capacity (124.6 cm³ g^–1), superior selectivity (20.2), and enhanced breakthrough interval\ntimes (21.6 min g^–1 at 273 K) for C₂H₂/CO₂ due to the exposed open metal site and the\npolar furan ring. This work offers novel pillared-layer-like MOFs\nwith quadrilateral channels for efficient C₂H₂ adsorption and purification.