Boosting C2H2/CO2 separation of metal-organic frameworks via anion exchange and temperature elevation

Developing new strategies to enhance adsorbents' gas separation performance is highly desirable. In this contribution, we created a post-synthetic modification approach to enhance the C2H2/CO2 separation performance for an ultramicroporous MOF (NKMOF-2) platform that underwent a single-crystal-to-single-crystal in the counter anion exchange process. Substitution of Cl- with BF4- not only greatly improved the water stability of the NKMOF-2 platform but also enhanced their adsorption capacity and separation performance. Mixture gas breakthrough experiments revealed that the anion exchange strategy was a powerful approach for boosting the selective adsorption of C2H2 over CO2. Moreover, we first observed that the C2H2/CO2 separation performance could be enhanced dramatically by elevating the test temperature. This study not only enriches the toolbox to create efficient MOF adsorbents for gas separation but also provides a fundamental understanding of the enhanced gas uptake and separation performance.