A new TIFSIX anion pillared metal organic framework with abundant electronegative sites for efficient C2H2/CO2 separation

Abstract

Separation of acetylene (C₂H₂) from carbon dioxide (CO₂) is important in industry to produce high purity C₂H₂ but challenged by the close physical properties. Herein, a novel microporous TIFSIX anion pillared metal organic framework ZNU-7 with abundant electronegative sites was prepared for efficient C₂H₂/CO₂ adsorption separation. The non-coordinating fluorine atoms in the large pores selectively capture C₂H₂ from CO₂ by hydrogen bonding. The C₂H₂ uptake capacity on ZNU-7 is as high as 92.1 cm³ g⁻¹, over 2.5 fold of the CO₂ uptake. The modest C₂H₂ adsorption heat of 35.3 kJ mol⁻¹ allows the facile desorption and regeneration of ZNU-7. The much stronger binding of C₂H₂ compared to CO₂ was further revealed by DFT calculations. The practical separation ability was confirmed by breakthrough experiments using C₂H₂/CO₂ gas mixtures with good recyclability. The dynamic separation factor of 3.0 for an equimolar C₂H₂/CO₂ mixture is comparable to those of many benchmark materials.