Engineering Pore Environments of Sulfate‐Pillared Metal‐Organic Framework for Efficient C2H2/CO2 Separation with Record Selectivity

Abstract

AbstractEngineering pore environments exhibit great potential in improving gas adsorption and separation performances but require specific means for acetylene/carbon dioxide (C2H2/CO2) separation due to their identical dynamic diameters and similar properties. Herein, a novel sulfate‐pillared MOF adsorbent (SOFOUR‐TEPE‐Zn) using 1,1,2,2‐tetra(pyridin‐4‐yl) ethene (TEPE) ligand with dense electronegative pore surfaces is reported. Compared to the prototype SOFOUR‐1‐Zn, SOFOUR‐TEPE‐Zn exhibits a higher C2H2 uptake (89.1 cm3 g−1), meanwhile the CO2 uptake reduces to 14.1 cm3 g−1, only 17.4% of that on SOFOUR‐1‐Zn (81.0 cm3 g−1). The high affinity toward C2H2 than CO2 is demonstrated by the benchmark C2H2/CO2 selectivity (16 833). Furthermore, dynamic breakthrough experiments confirm its application feasibility and good cyclability at various flow rates. During the desorption cycle, 60.1 cm3 g−1 C2H2 of 99.5% purity or 33.2 cm3 g−1 C2H2 of 99.99% purity can be recovered by stepped purging and mild heating. The simulated pressure swing adsorption processes reveal that 75.5 cm3 g−1 C2H2 of 99.5+% purity with a high gas recovery of 99.82% can be produced in a counter‐current blowdown process. Modeling studies disclose four favorable adsorption sites and dense packing for C2H2.