A novel carborane hybrid metal-organic framework with mortise-tenon architecture for reverse C2H2/CO2 separation and ternary C2H4 purification

The rational design of metal-organic frameworks capable of simultaneous reverse CH/CO separation and one-step CH purification from ternary CH/CO/CH mixtures has never been realized. Herein, we report a novel 2D carborane hybrid metal-organic framework ZNU-13 featuring zigzag 1D channel with contracted neck dimensions (3.9 Å × 3.9 Å) and expanded cavities (8.9 Å × 5.9 Å) to tackle this challenge. The robust porous structure was sustained through mortise-tenon interlocking of the neighboring carborane dicarboxylic-zinc 2D layers. Gas adsorption analysis reveals a rare adsorption selectivity hierarchy of CO > CH > CH, contrasting sharply with the analogue ZNU-14’s conventional selectivity pattern (CH > CH > CO). In-situ gas-loaded single-crystal X-ray diffraction (SCXRD) combined with density functional theory (DFT) calculations elucidates the higher CO binding affinity. CO is tightly trapped in the contracted channel pores with multiple interactions, while CH is located at the large cage cavity with weaker interactions. Various breakthrough experiments validate ZNU-13’s exceptional reverse CH/CO separation performance, exhibiting a dynamic separation factor of 3–5 and maintaining capacity under humid conditions for multiple cycles. Moreover, ZNU-13 enables direct production of polymer-grade CH from equimolar ternary gas mixtures through a single adsorption process, establishing a new benchmark for integrated gas purification systems.