Reaction kinetics of CO2 in aqueous 2-(2-aminoethylamino)ethanol solutions using a stirred cell reactor

A wide range of alkanolamines has been proposed in the literature for post-combustion CO2 capture. Recently, the use of polyamines as promising solvents for CO2 capture has been identified. In the present work, kinetics of the reaction of CO2 and 2-(2-aminoethylamino)ethanol, a diamine containing primary and secondary amino groups, in aqueous solutions has been studied using a stirred cell reactor with a horizontal gas-liquid interface. Measurements were performed over a temperature range from 298.15 to 303.15 K and the amine concentration ranging from 800 mol m−3 to 2500 mol m−3. Absorption rate experiments were carried out in the pseudo-first-order regime, enabling determination of the overall kinetic rate constant from a fall-in-pressure method. Both the zwitterion and termolecular mechanisms were applied to interpret the kinetic data. Based on the obtained overall pseudo-first-order rate constants kOV, individual reaction rate constants from two mechanisms were derived. At 308 K, the zwitterion formation rate constant for the CO2 reaction with AEEA is found to be 24.73 m3 mol−1 s−1. According to the termolecular mechanism, the second-order reaction rate constant with respect to AEEA was found to be 3.3 × 10−3 m6 mol−2 s−1 at the same temperature. Both these values are higher in comparison to MEA. The results of this study indicate that termolecular mechanism provides a better fit to the experimental data as indicated by the values of SSE.