Engineering Supramolecular Binding Sites in a Chemically Stable Metal-Organic Framework for Simultaneous High C2 H2 Storage and Separation

Abstract

Developing porous materials to overcome the trade-off between adsorption capacity and selectivity for C₂ H₂ /CO₂ separation remains a challenge. Herein, we report a stable HKUST-1-like MOF (ZJU-50a), featuring large cages decorated with high density of supramolecular binding sites to achieve both high C₂ H₂ storage and selectivity. ZJU-50a exhibits one of the highest C₂ H₂ storage capacity (192 cm³ g^-1 ) and concurrently high C₂ H₂ /CO₂ selectivity (12) at 298 K and 1 bar. Single-crystal X-ray diffraction studies on gas-loaded ZJU-50a crystal unveil that the incorporated supramolecular binding sites can selectively take up C₂ H₂ molecule but not CO₂ to result in both high C₂ H₂ storage and selectivity. Breakthrough experiments validated its separation performance for C₂ H₂ /CO₂ mixtures, providing a high C₂ H₂ recovery capacity of 84.2 L kg^-1 with 99.5 % purity. This study suggests a novel strategy of engineering supramolecular binding sites into MOFs to overcome the trade-off for this separation.

Keywords: Acetylene; Gas Separation; Porous Materials; Supramolecular Binding Sites; Trade-off.