Energy-Efficient CO2 Desorption of Ionic Liquid Solvents Facilitated by Homogeneous Lewis Acid Catalysts

Ionic liquids (ILs) show great potential for carbon dioxide (CO2) capture due to their designable structures and dual roles as absorbents and catalysts. Our previously designed IL solvent ([Cho][Triz]/TMS) showed good absorption performance but a slow regeneration rate. Here, a novel strategy to promote CO2 desorption in IL absorbents at lower temperatures using homogeneous Lewis acid IL (LAIL) catalysts was proposed. The cobalt (Co)-based LAIL [Bmim]2[CoCl4] exhibited superior performance, with the CO2 desorption amount enhanced by 54.1% and activation energy reduced by 30.3% compared with the blank test, leading to low regeneration energy consumption (0.90 GJ/t CO2), which was ascribed to a simultaneous increase in Brønsted and Lewis acid sites, promoting C–N bond cleavage by C2–H in [Bmim]22+ and Co sites in [CoCl4]2–. The environmental impact of IL-based CO2 capture processes, evaluated by the green degree method, demonstrated that the green degree production value of the IL-LAIL system is 79.6 and 673.6 gd/h higher than that of the IL and MEA systems, respectively, indicating greater environmental sustainability. This study provides a viable strategy for employing homogeneous catalysts to facilitate energy-efficient CO2 capture.