Maximizing Electrostatic Interaction in Ultramicroporous Metal-Organic Frameworks for the One-Step Purification of...

Developing efficient adsorbents for acetylene purification from multicomponent mixtures is of critical significance in the chemical industry, but the trade-off between regenerability and selectivity significantly restricts practical industrial applications. Here, we report ultramicroporous metal-organic frameworks with acetylene-affinity channels to enhance electrostatic interaction between C₂H₂ and frameworks for the efficient one-step purification of C₂H₂ from C₂H₂/CO₂/C₂H₄ mixtures, in which the electrostatic interaction led to high regenerability. The obtained SNNU-277 exhibits significantly higher adsorption capacity for C₂H₂ than that for both C₂H₄ and CO₂ at 298 K and 0.1 bar, while an ultrahigh selectivity of C₂H₂/C₂H₄ (100.6 at 298 K) and C₂H₂/CO₂ (32.8 at 298 K) were achieved at 1 bar. Breakthrough experiments validated that SNNU-277 can efficiently separate C₂H₂ from C₂H₂/C₂H₄/CO₂ mixtures. CO₂ and C₂H₄ broke through the adsorption column at 4 and 14.8 min g^-1, whereas C₂H₂ was detected until 177.6 min g^-1 at 298 K. Theoretical calculations suggest that the framework is electrostatically compatible with C₂H₂ and electrostatically repels C₂H₄ and CO₂ in the mixed components. This work highlights the importance of rational pore engineering for maximizing the electrostatic effect with the preferentially absorbed guest molecule for efficient multicomponent separation.