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 C₂H4 from ternary C₂H₂/C₂H₄/C₂H₆ mixtures by simultaneously trapping C₂H₂ and C₂H₆. Herein, we report the one-step C₂H₄ 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 C₂H₆ and C₂H₂. Its spindle-like cage exhibits an interesting shape matching with the targeted molecules, affording Zn(ad)(int) not only high separation selectivity for C₂H₆/C₂H₄ and C₂H₂/C₂H₄, but also excellent gas capacity. Breakthrough experiments show that polymer-grade C₂H₄ 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.