Multi-acid-site functionalized ionic liquids: A homogeneous catalyst for boosting low-temperature CO2 desorption efficiency

Amine-based CO 2 capture technologies face major hurdles in large-scale industrial deployment due to the high energy demand for solvent regeneration. Solid acid catalysts enable low-temperature desorption via proton transfer acceleration to reduce energy consumption, yet their practical deployment is hindered by active site leaching and deactivation, undermining stability and reliability. In this study, an acid-functionalized ionic liquid (AFIL), [DBAEH][AlCl 4 ], is introduced as a homogeneous catalyst to intensify CO 2 desorption from CO 2 -loaded MEA solutions at low temperatures. Its introduction accelerated the MEA regeneration rate by 64.46% and improved the overall regeneration efficiency by 26.87%. In addition, the AFIL effectively lowered the thermal energy demand during CO 2 desorption, reducing the relative regeneration heat duty by 17.00%. Notably, the catalyst maintained stable performance over ten consecutive absorption–desorption cycles, which indicate that the AFIL catalyst delivers superior catalytic performance and operational stability. Mechanistic insights derived from FT-IR and 13 C NMR characterizations suggested that the Brønsted acid sites (BASs) serve as proton donors, while the Lewis acid sites (LASs) promote C N bond scission, collectively enhancing carbamate breakdown and the deprotonation of protonated amines. Furthermore, the acid sites exhibit excellent stability against deactivation under catalytic conditions, rendering regeneration or replacement unnecessary. This dual–acid catalytic mechanism provided a promising avenue for lowering the regeneration heat load and operational expenses associated with industrial CO 2 capture processes.