One-step ethylene separation from ternary C₂ hydrocarbon mixture with a robust zirconium metal–organic framework

One-step separation of high-purity ethylene (C₂H₄) from C₂ hydrocarbon mixture is critical but challenging because of the very similar molecular sizes and physical properties of C₂H₄, ethane (C₂H₆), and acetylene (C₂H₂). Herein, we report a robust zirconium metal–organic framework (MOF) Zr–TCA (H₃TCA = 4,4′,4″-tricarboxytriphenylamine) with suitable pore size (0.6 nm × 0.7 nm) and pore environment for direct C₂H₄ purification from C₂H₄/C₂H₂/C₂H₆ gas-mixture. Computational studies indicate that the abundant oxygen atoms and non-polar phenyl rings created favorable pore environments for the preferential binding of C₂H₂ and C₂H₆ over C₂H₄. As a result, Zr–TCA exhibits not only high C₂H₆ (2.28 mmol g⁻¹) and C₂H₂ (2.78 mmol g⁻¹) adsorption capacity but also excellent C₂H₆/C₂H₄ (2.72) and C₂H₂/C₂H₄ (5.64) selectivity, surpassing most of one-step C₂H₄ purification MOF materials. Dynamic breakthrough experiments confirm that Zr–TCA can produce high-purity C₂H₄ (>99.9%) from a ternary gas mixture (1/9/90 C₂H₂/C₂H₆/C₂H₄) in a single step with a high C₂H₄ productivity of 5.61 L·kg⁻¹.