Novel Aqueous Amine Blend of Diethylenetriamine (DETA) and 2-Dimethylaminoethanol (DMAE) for Postcombustion CO ₂ Capture

In this study, a novel aqueous diethylenetriamine (DETA) and 2-dimethylaminoethanol (DMAE) amine blend was prepared to evaluate its performance to capture CO2 from a flue gas stream by conducting CO2 absorption and desorption investigations. CO2 absorption studies were performed under the operating conditions of temperature (T) varying from 298.15 to 333.15 K, CO2 partial pressure (PCO2) ranging from 10.13 to 25.33 kPa, DETA mole fraction (mDETA) in the range of 0.05 to 0.20, and solution concentration (C) varying from 1 to 3 mol/L. Equilibrium CO2 loading determination was the primary objective during the absorption study, and the highest equilibrium CO2 loading was determined to be 1.033 mol of CO2/mol of amine at T = 298.15, PCO2 = 25.33 kPa, mDETA = 0.20, and C = 1 mol/L. A semiempirical and an artificial neural network (ANN) modeling were formulated to validate the CO2 absorption outcomes. Fabulous percentage average absolute relative deviations of 2.96% and 3.99% were obtained from semiempirical and ANN modeling, respectively. CO2 desorption studies were conducted at T = 393.15 K and PCO2 = 25.33 kPa, and cyclic capacity was evaluated at C = 3 mol/L. The novel blend manifested a cyclic capacity of 1.86 mol of CO2/L solution, which is 71.90% greater than the 30 wt % traditionally available monoethanolamine (MEA). The heat of CO2 absorption (ΔHabs) of the blend was estimated by the Gibbs–Helmholtz equation, and it was found to be −66.43 kJ/mol, which is much lesser than that of MEA. Reaction chemistry was proposed and authenticated via species determination by 13C NMR analysis.