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

Abstract

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.