A study of species formation of aqueous tertiary and hindered amines using quantitative 13C NMR spectroscopy

Tertiary and sterically hindered amines have been chosen as potential candidate absorbents, recommended for their high carbon dioxide (CO2) loading capacity and easy regeneration. In this study, the CO2 absorption characteristics of these amines were studied using 1H nuclear magnetic resonance (NMR) and quantitative 13C NMR. The equilibrium experiments were conducted in the vapor–liquid equilibrium (VLE) apparatus, which was used to measure the CO2 absorption capacities and relative absorption rates of aqueous solutions of methyldiethanolamine (MDEA), 2-amino-2-methyl-1-propanol (AMP). The CO2 loaded absorbents were used for NMR measurement to determine the distribution of species formed in the absorbents. This process confirmed the reaction mechanisms of the individual absorbents in relation to CO2 absorption capacities.