Measurements of Equilibrium CO₂ Solubility in Aqueous Solutions of Ethylenediamine (EDA), N‐Ethylethanolamine (EEA), N,N‐Diethylethanolamine (DEEA), and Blends

The reversible nature of the reaction between CO 2 and amines results in finite partial pressure of CO 2 over the aqueous amine, thereby establishing a state of vapor–liquid equilibrium (VLE). Knowledge of the equilibrium features is essential for the design and operation of CO 2 absorbers. This high‐pressure equilibrium study provided CO 2 solubility vs. CO 2 partial pressure data for three amines, viz., ethylene diamine (EDA), N ‐ethylethanolamine (EEA), and N , N ′‐diethylethanolamine (DEEA). The dependence of solubility on amine molarity was studied at 308, 318, and 328 K in the 2–3.5 M range. Equilibrium CO 2 solubility was lowered when the temperature increased. It improved when amine molarity in solution was increased. It was found that DEEA loaded more CO 2 upon promotion with EDA and EEA. Mixtures of DEEA/EDA and DEEA/EEA achieved a loading capacity around 1 mol mol −1 . Empirical equations were developed using the least square regression method, and they predicted solubility data satisfactorily for CO 2 partial pressures up to 2500 kPa.