Kinetic study of CO2 absorption in aqueous solutions of 2‐((2‐aminoethyl)amino)‐ethanol using a stirred cell reaction calorimeter

Abstract

AbstractIn the literature, aqueous 2‐((2‐aminoethyl)amino) ethanol (AEEA) is identified as a promising solvent for postcombustion CO2 capture. In this work, the kinetics of CO2 absorption in the aqueous AEEA, containing a primary and a secondary amino group, is studied over a wide temperature range of 303.15‐343.15 K and the amine concentration in the range of 0.47‐2.89 M using the fall‐in‐pressure technique in a stirred cell reaction calorimeter setup with a horizontal gas‐liquid interface. The overall rate constants for (AEEA + H2O + CO2) reaction system are estimated in the pseudo–first‐order reaction regime. The kinetic models based on zwitterion and the termolecular reaction mechanisms are used to predict kinetic rate constants. The experimental kinetic data are better correlated using the zwitterion mechanism (AAD 9.18%) than that of the termolecular mechanism (AAD 10.4%). The density, viscosity, and physical solubility of pure components and aqueous binary mixtures of AEEA are also measured at the similar temperature and concentration ranges of rate kinetics. Empirical models are proposed to predict pure component density and viscosity data with AAD of 0.02% and 7.17%, respectively. The Redlich‐Kister model, the Grunberg‐Nissan model, and the O'Connell's model are used to correlate experimental density, viscosity, and physical solubility data of the binary mixtures with AAD of 0.034%, 4.92%, and 6.5%, respectively. The reaction activation energy (Ea ∼ 32 kJ/mol) of the (AEEA + H2O + CO2) system is calculated from the Arrhenius power‐law model using the zwitterion mechanism, which indicates lower energy barrier than that of the reported value for monoethanolamine (∼44 kJ/mol) in the literature.