Cation exchange in an anionic metal–organic framework enhancing propylene/propane separation

Abstract

Highly selective adsorptive separation of propylene/propane (C₃H₆/C₃H₈) using metal–organic frameworks (MOFs) is a promising approach to reducing energy consumption in the chemical industry. Here, we report a 3D anionic MOF obtained by the exchange of dimethylamine cations with small K⁺ ions. 77 K N₂ isotherms proved that the pore volume increased from 0.30 cm³ g⁻¹ to 0.42 cm³ g⁻¹ after ion exchange. Moreover, at near room temperatures (273 K and 298 K), both single-component gas adsorption capacity and selectivity of C₃H₆/C₃H₈ were enhanced. The C₃H₆/C₃H₈ separation potential was further confirmed by breakthrough experiments with equimolar C₃H₆/C₃H₈ mixtures. Similar separation properties were also observed in ethylene/ethane separation.