Comprehensive kinetic study of carbon dioxide absorption in blended tertiary/secondary amine solutions: Experiments and simulations

This study investigated the kinetics of CO2 absorption by aqueous solutions of 2-(ethylamino)ethanol (EAE) and 2-(butylamino)ethanol (BAE) using a stopped-flow device under varying concentrations of amine (0.02 ∼ 0.05kmol/m3) and temperature (293 K to 313 K), and also explored the kinetic behavior of N,N-diethylethanolamine (DEEA) when combined with EAE and BAE. The model involving a combination of the zwitterion mechanism and base catalysis mechanism was proposed with the better prediction of the reactions than other models. The AARD% for the two blended systems was 7.52 % and 7.95 %, respectively. The absorption mechanism and free energy barrier of blended amine aqueous solution were calculated and validated by Density Functional Theory (DFT) calculations. The reaction mechanism obtained from the calculation results is in good agreement with the kinetic model used in the experiment. This study highlights that consistency of model and simulation results and revealed the interaction effects of the blended amines. The effect of secondary amine chain length on absorption was also discussed, which gave the good significance to the further investigations and developments of blended CO2 solvents.