High adsorption capacity and selective separation of benzene by nonporous amorphous metallo-tetrahedra solids

The separation of benzene (Ben) and cyclohexane (Cy) is of great value in industrial production, but it is extremely difficult due to their similar boiling points and molecular structures. The exploitation of non-porous amorphous materials into adsorbents with high selectivity and adsorption capacity has attracted continuous and extensive research interest considering their excellent accessibility. Herein, we report the synthesis of three metallo-organic cages (MOCs) with high yield and production scale, which are utilized as excellent nonporous amorphous adsorbents for the capture and separation of Ben. Specifically, T-F achieves an ultrahigh selectivity of 199 for the separation of Ben/Cy (1:1, v/v) mixture in a two-component solid-vapor sorption experiment and shows good adsorption capacity of Ben of 109.39 cm3 g−1 at 298 K, thus presenting a remarkable advantage when compared with the reported adsorbents. The in-situ single crystal X-ray diffraction reveals that the adsorbed Ben molecules locate in the extrinsic clefts formed by adjacent MOCs. This study presents a rare yet successful example that utilizes nonporous amorphous MOCs as Ben sorbents with high capacity and selectivity and provides a new route for the development of adsorption materials.