Enhancing the separation efficiency of a C2H2/C2H4 mixture by a chromium metal–organic framework fabricated via post-synthetic metalation

Abstract

Chromium metal–organic frameworks (MOFs) are well-known for their stable porous frameworks, which are not fully explored due to the difficulty encountered in the synthesis process. In order to investigate the possibilities of Cr-MOFs as separation materials towards C₂ guest molecules, a novel iron MOF was constructed, which could serve as the scaffold to fabricate Cr-MOFs via post-synthetic metalation. The corresponding gas adsorption properties of the two iso-structural MOFs had been systematically investigated, illustrating the potential separation ability of Cr-MOF with respect to CO₂/C₂H₂ and C₂H₂/C₂H₄. Furthermore, the real and feasible behaviors of gas separation for Cr-MOF had been verified by dynamic breakthrough experiments. Compared to the iso-structural Fe-MOF, the fabricated Cr-MOF not only improved the chemical stability, but also enhanced the separation efficiency of the C₂ gas molecules. The systematic investigation clearly manifests the important role of chromium ions towards the separation of gas molecules and provides other insights into fabricating MOF-based separation materials.