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

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 C2 H2 and frameworks for the efficient one-step purification of C2 H2 from C2 H2 /CO2 /C2 H4 mixtures, in which the electrostatic interaction led to high regenerability. The obtained SNNU-277 exhibits significantly higher adsorption capacity for C2 H2 than that for both C2 H4 and CO2 at 298 K and 0.1 bar, while an ultrahigh selectivity of C2 H2 /C2 H4 (100.6 at 298 K) and C2 H2 /CO2 (32.8 at 298 K) were achieved at 1 bar. Breakthrough experiments validated that SNNU-277 can efficiently separate C2 H2 from C2 H2 /C2 H4 /CO2 mixtures. CO2 and C2 H4 broke through the adsorption column at 4 and 14.8 min g-1 , whereas C2 H2 was detected until 177.6 min g-1 at 298 K. Theoretical calculations suggest that the framework is electrostatically compatible with C2 H2 and electrostatically repels C2 H4 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.