One-step ethylene purification from ternary mixture by synergetic molecular shape and size matching in a honeycomb-like ultramicroporous material

Abstract

Physisorptive separation is a promising solution to reduce the energy cost for ethylene (C2H4) purification from C2 hydrocarbons. However, it remains a daunting challenge to effectively produce high-purity C2H4 in one step using physisorbents that simultaneously present high capture selectivities for acetylene (C2H2) and ethane (C2H6). Herein, we report the one-step C2H4 purification from ternary C2H2/C2H6/C2H4 mixtures with an ultramicroporous material Zn-ATA ([Zn2(ATA)3(ATA)2/2], ATA = 5-aminotetrazolate). Benefiting from the quasi-discrete pores comprised of honeycomb-like molecular cage and tailor-made pore window, C2H6 and C2H2 can be preferentially trapped with high selectivity via synergetic molecular shape and size matching, which is confirmed by in situ powder X-ray diffraction analyses and computational simulations. Breakthrough experiments show that polymer-grade C2H4 (>99.9 %) with an excellent productivity of 0.72 mmol g−1 can be directly obtained from the ternary mixture, indicating the great application prospect of Zn-ATA. This work provides critical clues to construct multifunctional materials via pore engineering for the separation of complicated gas mixtures.