Hybrid Absorption–Adsorption of CO₂ Capture Using Type III Porous Liquids: Experimental and Rigorous Phase Equilibrium Models

Porous liquid has the porosity of a porous solid and fluidity of a liquid, which is expected to become a new generation of CO2 capture medium. The experimental results show that different solvent systems of ZIF-8-based porous liquids have different CO2 capture characteristics. To reveal their differences, a hybrid absorption–adsorption model and the single equilibrium stage model were established to describe the phase behaviors of the CO2 capture. Results show that the average relative error between predicted results by the hybrid model and experimental results is less than 10%. The hybrid effect can enhance the sorption amount relative to the solvent, and the percentage of absorption and adsorption will reach equal at a certain pressure. The separation factor of hybrid is between solvent and porous material and decreases with the increase of pressure, but the liquid membrane can make the separation factor break through the limitation of its solvent. With the increase of the content of porous material (ZIF-8) in porous liquid, the hybrid sorption amount increases and the separation factor decreases. Through a hybrid of absorption and adsorption, porous liquids have the potential to replace traditional physical solvents in CO2 capture.