Novel DMAEE-Based Dual-Amine Solvent for Low-Energy CO₂ Capture Developed through Activator Screening through ¹³C NMR Analysis

Aqueous blends of the tertiary amine 2-[2-(dimethylamino)ethoxy]ethanol (DMAEE) in combination with several primary and secondary amines, including ethanolamine (MEA), benzylamine (BZA), 2-(ethylamino)ethanol (EAE), 2-(methylamino)ethanol (MAE), and 2-amino-2-methyl-1-propanol (AMP), were investigated as innovative absorbents for CO2 capture. This study examines the potential of DMAEE-based blends to overcome some of the key limitations of conventional sorbents through a comprehensive evaluation of their CO2 absorption and desorption performances. Key parameters, including CO2 equilibrium solubility, absorption and desorption rates, and regeneration energy requirements, were assessed and compared with those of the conventional 5 M MEA under the same operating conditions. To gain more insight into the reaction mechanisms governing these systems, 13C NMR spectroscopy was used to identify and quantify the species generated during CO2 capture. Results demonstrated that, except for the AMP:DMAEE blend, which precipitated during the CO2 absorption process, all DMAEE-based blends exhibited superior desorption performance compared to MEA, achieving up to three times the desorption rate and approximately 40% lower heat duty. Among these, EAE:DMAEE emerged as a promising candidate for large-scale applications, combining high capture efficiency with reduced energy consumption.