Measuring solubility of carbon dioxide in aqueous blends of N-methyldiethanolamine and 2-((2-aminoethyl)amino)ethanol at low CO2 loadings and modelling by electrolyte SAFT-HR EoS

• Solubility data for carbon dioxide in aqueous (MDEA + AEEA) solutions is obtained.
• Mole ratio AEEA/MDEA = 0.12500, 0.10000 and 0.05000 at constant amine concentration.
• The data are at T = (313.15, 328.15, 343.15 and 358.15) K and P = (7.3 to 386.6) kPa.
• Electrolyte SAFT-HR EoS was used to model the quaternary solution.
• The AAD% of the EoS for calculation of the total pressure = 7.74.

In this work, new solubility values for CO2 absorption in aqueous solutions of N-methyldiethanolamine (MDEA) in the presence of different mole ratios of 2-((2-aminoethyl)amino)ethanol (AEEA) at low pressures are obtained. The total molar amine concentration of all the solutions has been fixed equal to 3.360 mol · L−1 (5.370 mol amine · kg−1 water). The mole ratio of AEEA/MDEA was set to 0.12500, 0.10000 and 0.05000. The experimental total pressure varied from (7.3 to 386.6) kPa and the experimental temperature was set to (313.15, 328.15, 343.15 and 358.15) K. The electrolyte SAFT-HR (eSAFT-HR) equation of state (EoS) (Najafloo et al., 2014) has been successfully applied to model the solubility of CO2 in aqueous mixtures of AEEA and MDEA. The overall average absolute relative per cent deviation (AAD%) in calculating the total pressure as a function of CO2 loading is 7.74 for (AEEA + MDEA + CO2 + H2O) quaternary system at the four values of temperature. To verify the predictive ability of the model, the eSAFT-HR EoS was extrapolated to the Zoghi and Feyzi (2013) solubility results of the same quaternary system that were obtained at higher pressures or higher CO2 loadings at the same temperatures. The AAD of the present model is 11.39% lower.

CO2 loading at various partial pressures of CO2 in aqueous 5.370 mol/kg (MDEA + AEEA) mixture at T = 343.15 K and at the molar ratio of AEEA/MDEA = 0.12500: ♦, 0.10000: ■ and 0.05000:▴, 0.00000: ●. Lines are used only to join the experimental data points. Source of data: this work.Figure optionsDownload as PowerPoint slide