Novel Pillared-Layer-like Metal–Organic Frameworks with Quadrilateral Channels for Efficient Separation of C₂H₂ from C₂H₂/CO₂ and C₂H₂/C₂H₄ Mixtures

Abstract

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