Physical/Chemical Solubility and Chemical Equilibrium Analysis of Carbon Dioxide Absorption in a Potential and Novel Blended Amine Solution of 2-Methylaminoethanol (MAE) and N,N-Diethylethanolamine (DEEA)

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This study comprehensively reports the physical and chemical equilibrium solubility data, along with a detailed chemical equilibrium analysis, of carbon dioxide (CO 2 ) absorption into a blended amine solution consisting of 2-methylaminoethanol (MAE) and N,N-diethylethanolamine (DEEA). Four models were employed to analyze the CO 2 physical solubility using N 2 O analogy, with the Artificial Neural Network (ANN) model exhibiting an average absolute relative deviation (AARD) of 2.78%. The CO 2 chemical solubilities were then analyzed experimentally at various temperatures (298–313 K), CO 2 partial pressures (8–100 kPa), and concentrations (1–5 mol/L). In addition, the heat of CO 2 absorption was estimated to be 46.96 kJ/mol using the Gibbs–Helmholtz equation, which is approximately half that of the benchmark amine, monoethanolamine (MEA). A rigorous 13 C NMR investigation was conducted to identify and quantify the species formed during the absorption process across varying temperatures, CO 2 loadings, and MAE/DEEA molar ratios, to clarify the capture mechanisms and intricate role of MAE and DEEA in the capture process. As a result, at an MAE/DEEA ratio of 1:4, the carbamate concentration peaks at a CO 2 load of about 0.45 mol of CO 2 /mol of amine at about 0.6 mol/L, which is only one-third of the concentration at the higher ratio, which contributes to the reduction of energy consumption for CO 2 desorption.