Linker Desymmetrisation Directs Low-polar Cages in an Anion-Pillared MOF for Acetylene and Ethylene Purification from Ternary Mixtures

Abstract

Anion-pillared metal-organic frameworks (APMOFs) constitute a promising class of porous adsorbents, yet precise organization of anionic groups to maximize their strong electronegative character while circumventing highly polar pore environments and high adsorption enthalpies remains a substantial challenge. Here, we report a novel APMOF, CTGU-45, featuring an atypical low-polar cage surface distinct from reported APMOFs and then explore its C2H2 and C2H4 purification from ternary C2H2/CO2/CH4 and C2H2/C2H4/C2H6 mixtures. Theoretical calculation results revealed the mechanisms of simultaneous recognition of C2H2 and C2H6 molecules from C2 hydrocarbons: the SiF62- pillars provide strong binding sites for C2H2 via C-H···F hydrogen bonds, while the TIB-derived low-polar surface offers an optimal environment for C2H6 adsorption through synergistic C-H···π and C-H···N interactions. Dynamic breakthrough experiments further confirm the efficient separation of C2H2/CO2, C2H2/CO2/CH4, and notably one-step production of polymer-grade C2H4 (≥ 99.95%, 9.57 L kg-1) from ternary C2H2/C2H4/C2H6 mixtures with low regeneration energy. Crucially, CTGU-45 can be synthesized on a 500 mL scale with retained performance, underscoring its practical feasibility and laying a solid foundation for future industrial applications.