Improving CO2 solubility in a hybrid sorbent of 1-hexyl-3-methylimidazolium bis(trifluoromethylsulfonyl)imide/mesoporous titanium dioxide/water with confinement effect

Confinement effect is an effective method to enhance carbon dioxide (CO 2 ) solubility. In this study, a hybrid sorbent of 1-hexyl-3-methylimidazolium bis(trifluoromethylsulfonyl)imide ([Hmim][NTf 2 ])/mesoporous titanium dioxide (M-TiO 2 )/water (H 2 O) was developed, and its confinement effect was regulated by changing the pore structure of M-TiO 2 . CO 2 solubility in the hybrid sorbent was measured experimentally, and the thermodynamic properties including Henry’s constant and desorption enthalpy were calculated. Furthermore, the confinement effect in the hybrid sorbent was quantified. Additionally, the hybrid sorbent was recycled with a multi-cycle experiment. The results showed that M-TiO 2 calcined at 773.2 K (MT500) could lead to an efficient confinement effect. CO 2 solubility in the hybrid sorbent increased by 49.8% compared to that of H 2 O when the mass fraction of [Hmim][NTf 2 ]/MT500 was 5.0% (mass), where the contribution of confinement effect on Gibbs free energy occupied 5.2%.