A core-shell IL@MOF composite with ultra-high selectivity in multiple CO2 purification systems

Abstract

Porous adsorbents are widely used for the adsorptive separation of carbon dioxide (CO2) from gas mixtures, offering a promising solution to address both the energy crisis and environmental issues. However, developing highly efficient CO2 selective adsorbents has been challenging due to the similar physicochemical properties of CO2 and other gases. To overcome this challenge, we herein have developed a core–shell composite utilizing ionic liquids (ILs) and metal–organic frameworks (MOFs) based on the dissolution-diffusion mechanism. The unique solubility differences of ILs for various gas molecules, particularly their strong solubility for CO2, allow only CO2 to be adsorbed while excluding other gases. As a result, the composite exhibits a remarkable separation selectivity for CO2/C2H2, CO2/CH4 and CO2/N2. Breakthrough experiments have verified the outstanding performance of this core–shell composite in separating gas mixtures containing CO2 impurities. Remarkably, this composite can be synthesized by a simple method, which is more practical for large-scale production.