(537c) MOF-Supported Ionic Liquids As Efficient CO2 Adsorbents for Direct Air Capture | AIChE

(537c) MOF-Supported Ionic Liquids As Efficient CO2 Adsorbents for Direct Air Capture


Lin, H. - Presenter, Washington State University
Wang, C., Washington State University
Metal-organic frameworks (MOFs) are promising carbon dioxide (CO2) adsorbents because of their remarkably high surface area, controllable pore structures, and predictable functional groups. However, few research groups reported investigating ionic liquids (ILs) loaded on MOFs for direct air capture of CO2. Herein, we prepared UiO-66 and treated it with methanol solvent and thermal activation. It showed ~3 times enhanced CO2 capture capacity, from 15.1 mg/g to 45 mg/g at 1 bar of CO2 pressure, and excellent recyclability. The methanol treatment efficiently removes the residual guest molecules, including N, N-dimethylformamide, dangling organic linkers, and their derivatives in the micropores of UiO-66 and improves the surface area, pore volume, and void fraction to enhance the CO2 capacity. The molecular dynamic simulation also proved an excellent linear relationship between the surface areas, void fraction, and CO2 capacity. When we load ionic liquids (e.g., [Na][Im]) on the methanol-treated UiO-66, the CO2 capacity increases from 0.003 mmol/g to the maximum of 0.212 mmol/g at 0.4 mbar of CO2 partial pressure. The [Na][Im]/UiO-66 displayed good recyclability. The kinetic studies showed that it followed a pseudo-first-order reaction rate model, and the reaction rate is closely related to the IL layer thickness. This work elucidates the IL/MOF activation mechanism and its applications in direct air capture of CO2.