Hierarchically porous ZIF-8 aerogel composites for selective adsorption and separation of xylene isomers

Metal-organic aerogels derived from ZIF-8 frameworks were developed for xylene isomer separation, demonstrating unique structural and adsorptive properties. The incorporation of ZIF-8 transformed non-porous agar (AG) aerogel into a hierarchically porous composite, albeit with a reduced surface area compared to pure MOFs. Vapor-phase adsorption and breakthrough experiments revealed exceptional p -xylene selectivity ( p X/ o X = 19) in ZIF-8/AG composites, though with diminished adsorption capacity relative to pristine ZIF-8. While exhibiting substantial liquid-phase adsorption, the composite showed limited gas-phase selectivity, indicating hydrogen-bonding-mediated adsorption mechanisms. This work highlights the correlation between selectivity and capacity in MOF-based aerogel adsorbents for the separation of aromatics.