Enhanced CO2 capture by binary systems of pyridinium-based ionic liquids and porous ZIF-8 particles

Absorption and adsorption technology as widely used methods have been reported for carbon dioxide (CO 2 ) separation. In order to combine the advantages of absorption and adsorption methods, ionic liquids (ILs) as absorption function and zeolitic imidazolate framework-8 (ZIF-8) as adsorption function were integrated into a slurry to efficiently capture CO 2 by the absorption-adsorption method. In this study, two pyridinium-based ILs, [C 4 Py][NTf 2 ] and [C 4 Py][N(CN) 2 ] were synthesized, and mixed with different concentration of ZIF-8 to form hybrid slurries. CO 2 solubility in the different hybrid slurries at temperatures from 303.15 to 333.15 K was measured. The results indicated that CO 2 solubility increases significantly with increasing pressure and decreases with increasing temperature. Moreover, CO 2 solubility increases with the increase of ZIF-8 content, indicating that the addition of ZIF-8 into ILs can obviously enhance CO 2 solubility. CO 2 solubility in the ZIF-8/[C 4 Py][NTf 2 ] slurry increases by 24% compared with the corresponding pure IL at 303.15 K and 1.80 MPa. The absorption-adsorption mechanism was studied using FT-IR and NMR spectroscopy. It was demonstrated that CO 2 absorption and adsorption in the ZIF-8/ILs hybrid slurries is a physical process. Furthermore, the ZIF-8/[C 4 Py][NTf 2 ] slurry can also keep the stable absorption performance after five consecutive absorption and desorption cycles. Considering the excellent capacity, thermal stability and recyclability, the porous materials/ILs slurry will provide new insight to CO 2 capture compared with the conventional absorbents.