Versatile and dense sites in an interpenetrated adsorbent for one-step ethylene separation from quaternary gas-mixtures

One-step purification of ethylene (C₂H₄) from complex crude C₂H₄ products containing acetylene (C₂H₂), ethane (C₂H₆), and carbon dioxide (CO₂) impurities is highly critical and desirable. Herein, we customize the pore environments with versatile and dense adsorption sites in a novel interpenetrated adsorbent, Zn-mtz-ina, to simultaneously remove C₂H₂, CO₂, and C₂H₆ from C₂H₄. As a result, Zn-mtz-ina exhibits benchmark adsorption capacity for C₂H₂ (3.01 mmol g⁻¹) and IAST selectivity for C₂H₂/C₂H₄ (4.7), along with a low C₂H₄ uptake (1.60 mmol g⁻¹) among reported similar adsorbents. Dynamic breakthrough experiments confirm the direct production of polymer-grade C₂H₄ (>99.9%) from a C₂H₂/C₂H₆/CO₂/C₂H₄ (1/33/33/33, v/v/v/v) gas mixture with a high productivity of 0.36 mmol g⁻¹ under ambient conditions. The underlying separation mechanisms and guest–host interactions are elucidated through gas-loaded single crystal analysis, density functional theory calculations, and visualized Hirshfeld surface analysis.