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 C 2 H 2 and frameworks for the efficient one-step purification of C 2 H 2 from C 2 H 2 /CO 2 /C 2 H 4 mixtures, in which the electrostatic interaction led to high regenerability. The obtained SNNU-277 exhibits significantly higher adsorption capacity for C 2 H 2 than that for both C 2 H 4 and CO 2 at 298 K and 0.1 bar, while an ultrahigh selectivity of C 2 H 2 /C 2 H 4 (100.6 at 298 K) and C 2 H 2 /CO 2 (32.8 at 298 K) were achieved at 1 bar. Breakthrough experiments validated that SNNU-277 can efficiently separate C 2 H 2 from C 2 H 2 /C 2 H 4 /CO 2 mixtures. CO 2 and C 2 H 4 broke through the adsorption column at 4 and 14.8 min g -1 , whereas C 2 H 2 was detected until 177.6 min g -1 at 298 K. Theoretical calculations suggest that the framework is electrostatically compatible with C 2 H 2 and electrostatically repels C 2 H 4 and CO 2 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.