Fully inverse adsorption enables one-step high-purity C₂H₂ separation from ternary C2 mixtures in a robust porous...

Direct harvesting of electronic-grade acetylene (C₂H₂) from ternary C2 mixtures is a great challenge due to the ubiquitous adsorption preference of conventional porous materials (C₂H₂ > ethylene (C₂H₄) > ethane (C₂H₆)). Here, we report a strategy to reverse this selectivity by leveraging ligand functionalization in porous crystals. Through the incorporation of trifluoromethyl/methyl groups into a pyrazole-carboxylate linker, we engineer a series of MOF-5 analogs. The optimal material, NTU-98, fully reverses the adsorption trend of C2 hydrocarbons (C₂H₆ > C₂H₄ > C₂H₂), enabling direct production of C₂H₂ with >99.99% purity from ternary feeds at room temperature in one-step. Combined density functional theory calculations and gas-loaded crystallographic analyses unveil the molecular mechanism: methyl groups precisely positioned within the cages enhance host-guest interactions with C₂H₄ and C₂H₆, while suppressing the binding affinity for C₂H₂. This work presents a porous crystal for direct C₂H₂ purification from ternary feeds and a blueprint for designing microporous environments targeting challenging separations.