Microporous metal-organic frameworks with open metal sites and π-Lewis acidic pore surfaces for recovering ethylene from polyethylene off-gasElectronic supplementary information (ESI) available: Additional structural figures, FT-IR spectra, TGA curves, PXRD patterns, and gas adsorption isotherms. CCDC 1847821 and 1849673. For ESI and crystallographic data in CIF or other electronic format see DOI: 10.1039/c8ta06923a

There is an urgent demand for recovering ethylene (C 2 H 4 ) from polyethylene off-gas since it allows for a more efficient conversion of monomers with high economic value. Herein, we report a three-dimensional (3D) porous MOF [Cu 2 (L)(H 2 O) 2 ]·5DMF·dioxane·3H 2 O ( FJU-101 , H 4 L = N , N ′-bis(5-isophthalic acid)naphthalenediimide, DMF = N , N ′-dimethylformamide) with π-Lewis acidic pore surfaces and superior gas storage/separation performance. Under ambient conditions, the activated FJU-101a exhibits a high C 2 H 4 uptake of 142 cm 3 (STP) per g and more importantly, the dynamic fixed-bed breakthrough test indicates that the recovery of C 2 H 4 from simulated polyethylene off-gas through a column packed with FJU-101a adsorbent can be efficiently achieved. Such a separation is essential to recycle ethylene for its commercial usage. In addition, FJU-101a also exhibits an extraordinarily high gravimetric uptake of CO 2 (219.1 cm 3 g −1 ) at 273 K and 1 bar, which is only slightly lower than that of the best CO 2 adsorption material, namely, MgMOF-74 (230 cm 3 g −1 ) under similar conditions. By employing electron-deficient ligands to fabricate MOFs, we could not only improve gas uptake capacity, but also stabilize the framework robustness.