The investigation of the reaction mechanism of CO₂ in HMDA/DEEA and EAE/1DMA2P aqueous solution systems

Revealing the reaction mechanism of CO₂ absorption by mixed amine solutions can provide theoretical guidance for establishing complex kinetic models. This study investigated the CO₂ capture mechanisms of blended amine systems, specifically 1,6-hexamethyl diamine (HMDA)-N,N-diethylethanolamine (DEEA) and 2-(ethylamino)ethanol (EAE)-1-dimethylamino-2-propanol (1DMA2P), utilizing ¹³C nuclear magnetic resonance (NMR) spectroscopy and quantum mechanical calculations. The ¹³C NMR analysis identified the formation and conversion of species during CO₂ absorption, while quantum calculations elucidated the reaction energetics. The results indicate that tertiary amines (DEEA or 1DMA2P) facilitate CO₂ absorption by promoting the desorption of protonated primary amines (HMDA or EAE), thereby enhancing the absorption rate. This research provides insights into the role of tertiary amines in blended systems, guiding the development of efficient and low-energy amine solvents for CO₂ capture.