CO2 absorption with aqueous tertiary amine solutions: Equilibrium solubility and thermodynamic modeling

Abstract

Abstract In this work, the equilibrium CO2 solubilities of five tertiary amines, namely Triethanolamine (TEA), N-methylethanolamine (MDEA), 2-(Dimethylamino)ethanol (DMEA), 3-dimethyl-amino-1-propanol (3DMA1P), and Diethylethanolamine (DEEA) were measured over the temperature range of 298.15–313.15 K, and at CO2 partial pressures up to 60.8 kPa. The activity-structure relationship was studied on the molecular level to account for the differences in equilibrium CO2 solubility. The M-KE model was applied to correlate the vapor-liquid-equilibrium data of the five tertiary amine-H2O-CO2 systems. Results show that the model is able to correlate experimental data very well and gives reasonable prediction results with average absolute deviation (AAD) of 2.5% for TEA, 3.3% for MDEA, 1.3% for DMEA, 1.0% for 3DMA1P and 0.8% for DEEA. In addition, the CO2 absorption heat was calculated using the Clausius-Clapeyron equation. The potential for the five amines to be considered as alternative solvents for CO2 capture was evaluated in terms of equilibrium CO2 solubility, second order reaction rate constant and CO2 absorption heat.