Constructing hollow carbon sphere liquid with permanent porosity via electrostatic modification of polyionic liquids for CO₂ gas adsorption

Porous liquids (PLs) are a type of porous materials that combine the porosity of solids and fluidity of liquids, which has attracted widespread attention. In this paper, we report a new TypeⅠhollow carbon sphere-based porous liquids, which are constituted of hollow carbon sphere (HCS) as the porous host, polymeric ionic liquid (PILs) as the corona and poly(ethylene glycol) 4-nonylphenyl 3-sulfopropyl ether potassium salt (PEGS) as the canopy. The viscosity of PLs is 8900 mPa·s at 50 ℃ (like syrup), which has good fluidity. Under 3 MPa pressure conditions, the best CO₂ adsorption capacity of 450-P[VHIm]Br-PEGS and 450-P[VBBI]Cl-PEGS are 2.06 and 1.90 mmol/g at 25 °C, respectively, higher than PILs-PEGS. Under the same conditions, the CO₂ adsorption capacity of PLs is 10.5 times higher than that of N₂. Therefore, HCS-based PLs have the potential for CO₂/N₂ selective gas separation. Not only PILs and the anionic alkyl chain of the outer layer widen the liquid range of PLs, but also is suitable for preparing PLs with other cavity units.