An amino-functionalized metal–organic framework for efficient separation of xenon/krypton

Abstract

The separation of xenon and krypton is an important yet energy-intensive industrial process. Adsorptive separation based on adsorbents like metal–organic frameworks (MOFs) is of great interest owing to its tremendous energy-saving capability. Herein, we report a new copper nicotinate MOF with free amino groups for highly efficient Xe/Kr separation. This MOF shows two-fold interpenetrated dia topology with a relatively compact pore structure (4.6 × 5.9 Ų). Single-component adsorption isotherms reveal that this MOF exhibits simultaneously high Xe uptake capacity at low pressure (2.71 mmol g⁻¹ at 20 kPa) and selectivity (18.6), which are comparable to those of reported benchmark MOF materials. A structural modelling study indicates that the incorporation of amino functional groups enhances the binding affinity of the MOF for Xe. Breakthrough experiments confirm that this material can efficiently separate Xe and Kr (purity >99.9%) from the Xe/Kr mixture (20/80, v/v).