Pillar-layered metal-organic frameworks with benchmark C2H2/C2H4 and C2H6/C2H4 selectivity for one-step C2H4 production

Abstract

Energy-efficient adsorptive separation shows great potential for the one-step production of high-purity ethylene (C2H4) from ternary C2 hydrocarbons. However, it remains a formidable challenge to fabricate high-performance adsorbents that exhibit simultaneous high selectivity (>2) towards acetylene/ethylene (C2H2/C2H4) and ethane/ethylene (C2H6/C2H4). Herein, we report a pillar-layered metal–organic framework, Ni(sdba)(dabco)0.5 (H2sdba = 4,4′-sulfonyldibenzoic acid; dabco = 1,4-diazabicyclo [2.2.2] octane), for preferential trapping of C2H6 and C2H2 over C2H4. The abundant accessible binding sites endow Ni(sdba)(dabco)0.5 with outstanding C2H2/C2H4 (2.28) and C2H6/C2H4 (2.47) selectivity with high C2H6 (3.15 mmol g−1) and C2H2 (4.41 mmol g−1) uptake among porous materials reported for one-step C2H4 purification. Dynamic breakthrough experiments demonstrated the feasibility of producing high-purity C2H4 (>99.9%) from C2H2/C2H6/C2H4 gas-mixtures (1/1/1 and 1/9/90, v/v/v) in a single step. Computational simulations reveal that the aromatic-rich pore spaces, which decorated with accessible interlayer uncoordinated oxygen atoms of sulfonyl groups and alkyl functionalities, can provide multiple C-H···O, C-H···π, and C-H···H interactions for selectively recognizing C2H6 and C2H2 over C2H4.