Enhancing low-temperature desorption performance toward energy-saving CO2 capture via the multifunctional design of diethylethanolamine-based biphasic solvents

Biphasic solvents with primary/secondary amines as the primary absorbent involve a high heat of reaction and low desorption efficiency, limiting their development. A tertiary amine-based biphasic solvent composed of diethylethanolamine (DEEA), 2-Amino-2-methyl-1-propanol (AMP), ethyl acetoacetate (EAA), and H 2 O (referred to as DEEA/AMP/EAA/H 2 O) was proposed, which exhibited superior low-temperature desorption performance and ultra-low regeneration energy. EAA was revealed to facilitate the low-temperature desorption by reducing the activation energy from 6.8 to 2.3 kcal/mol. When regenerated only by heating to 353.15 K, the CO 2 -rich phase showed a significant desorption efficiency of 88.2 %; the desorption capacity and desorption rate were even 2.23 times and 6.84 times higher than 30 wt% MEA at 393.15 K. Moreover, the desorption heat dominated by the deprotonation of tertiary amine was as low as 0.92 GJ/t CO 2 ; and low-temperature regeneration brought extremely low latent heat below 0.062 GJ/t CO 2 . Thus, the total regeneration energy was as low as 1.16 GJ/t CO 2 . In addition, EAA could trigger the phase separation and increase the absorption rate constant from 3.87 E−4 to 1.36 E−3 s −1 , even higher than 30 wt% MEA. The addition of AMP further increased the CO 2 loading (4.34 mol/L) and CO 2 distribution (97.43 %) of the CO 2 -rich phase.