Engineering Pore Environments of Sulfate‐Pillared Metal‐Organic Framework for Efficient C<sub>2</sub>H<sub>2</sub>/CO<sub>2</sub> Separation with Record Selectivity
Xing Liu, Peixin Zhang, Hanting Xiong, Yan Zhang, Ke Wu, Junhui Liu, Rajamani Krishna, Jingwen Chen, Shixia Chen, Zheling Zeng, Shuguang Deng, Jun Wang
Abstract
Abstract Engineering pore environments exhibit great potential in improving gas adsorption and separation performances but require specific means for acetylene/carbon dioxide (C 2 H 2 /CO 2 ) 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 C 2 H 2 uptake (89.1 cm 3 g −1 ), meanwhile the CO 2 uptake reduces to 14.1 cm 3 g −1 , only 17.4% of that on SOFOUR‐1‐Zn (81.0 cm 3 g −1 ). The high affinity toward C 2 H 2 than CO 2 is demonstrated by the benchmark C 2 H 2 /CO 2 selectivity (16 833). Furthermore, dynamic breakthrough experiments confirm its application feasibility and good cyclability at various flow rates. During the desorption cycle, 60.1 cm 3 g −1 C 2 H 2 of 99.5% purity or 33.2 cm 3 g −1 C 2 H 2 of 99.99% purity can be recovered by stepped purging and mild heating. The simulated pressure swing adsorption processes reveal that 75.5 cm 3 g −1 C 2 H 2 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 C 2 H 2 .