One-Step Ethylene Purification from Ternary Mixtures in a Metal-Organic Framework with Customized Pore Chemistry and Shape

Adsorptive separation is an energy-efficient technology for the separation of C2 hydrocarbons. However, it remains a critical problem to directly produce high-purity C₂ H₄ from ternary C₂ H₂ /C₂ H₄ /C₂ H₆ mixtures by simultaneously trapping C₂ H₂ and C₂ H₆ . Herein, we report the one-step C₂ H₄ purification from the ternary mixture by a metal-organic framework Zn(ad)(int) (ad=adeninate; int=isonicotinate). The material combines dense heterocyclic rings and accessible uncoordinated O atoms as strong binding sites for C₂ H₆ and C₂ H₂ . Its spindle-like cage exhibits an interesting shape matching with the targeted molecules, affording Zn(ad)(int) not only high separation selectivity for C₂ H₆ /C₂ H₄ and C₂ H₂ /C₂ H₄ , but also excellent gas capacity. Breakthrough experiments show that polymer-grade C₂ H₄ can be separated from the ternary mixtures with a record productivity of 1.43 mmol g^-1 . In situ powder X-ray diffraction and Fourier transform infrared spectrum analyses further provide deep insights into the separation mechanism.