An Asymmetric Anion-Pillared Metal-Organic Framework as a Multisite Adsorbent Enables Simultaneous Removal of Propyne and Propadiene from Propylene.

The one-step removal of multi-component gases based on a single material will significantly improve the efficiency of separation processes but it is challenging, owing to the difficulty to precisely fabricate porous materials with multiple binding sites tailored for different guest molecules. Now a niobium oxide-fluoride anion-pillared interpenetrated material ZU-62 (NbOFFIVE-2-Cu-i, NbOFFIVE=NbOF5 2- ) is presented. It features asymmetric O/F node coordination for the simultaneous removal of trace propyne and propadiene from propylene. The narrow distribution nanospace (aperture of Site I 6.75 Å, Site II 6.94 Å, Site III 7.20 Å) derived from the special coordination geometry within ZU-62 customized the corresponding energy-favorable binding sites for the propyne and propadiene that enable propadiene uptake (1.74 mmol g-1 ) as well as excellent propyne uptake (1.87 mmol g-1 ) under ultra-low pressure (5000 ppm). The multisite capture mechanism was revealed by modeling studies.