An experimental and theoretical study on the effects of amine chain length on CO2 absorption performance

Abstract To explore the effect of amine chain length on CO 2 absorption performance, the reaction kinetics of CO 2 absorption in aqueous 1‐dimethylamino‐2‐propanol (DMA2P), 1‐diethylamino‐2‐propanol (DEA2P), 2‐(methylamino)ethanol (MAE), and 2‐(ethylamino)ethanol (EAE) solutions with different concentrations were explored using the stopped‐flow apparatus. Additionally, Density Functional Theory (DFT) calculations were conducted to examine the reaction mechanism and the free energy barrier of the elementary reactions underlying CO 2 absorption in these four aqueous amine solutions. Kinetic models for CO 2 absorption in tertiary amines and secondary amines were established, based on the base‐catalyzed hydration mechanism and the zwitterion mechanism, respectively, both of which perform well in predicting the relationship between k 0 and the amine concentration. The free energy barrier obtained by DFT is consistent with the activation energy barrier trend obtained by experiment. In addition, the effect of chain length on the free energy barrier was investigated through the chemical bond and weak interaction analysis.