Supramolecular linker-directed assembly of a ‘trap-and-diffusion’ MOF for one-step purification of polymer-grade C₂H₄ from C₂ hydrocarbons

Simultaneously removing ethane (C₂H₆) and acetylene (C₂H₂) from ethylene (C₂H₄) streams is advantageous for industrial production yet remains challenging for physisorbents. Herein, we report a microporous metal–organic framework (MOF), NKM-47, that achieves one-step C₂H₄ purification. NKM-47 was designed via a supramolecular linker-directed assembly approach and features a ‘trap-and-diffusion’ porous architecture composed of orthogonally arranged molecular pockets and 1D channels. The N/O-rich molecular pockets selectively capture the smallest and largest C₂ species (C₂H₂ and C₂H₆) while the channels permit preferential diffusion of medium-sized C₂H₄. NKM-47 enables one-step production of polymer-grade C₂H₄ (99.99% purity) from both binary and ternary C₂ gas mixtures under ambient conditions. This study presents the first example of a trap-and-diffusion mechanism for C₂ hydrocarbon separation in MOFs, enabling the single-step purification of C₂H₄ through the selective diffusion of a species with intermediate physicochemical properties.