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

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.