13C NMR Spectroscopy of a Novel Amine Species in the DEAB-CO2-H2O system: VLE Model

In the present work, ion speciation studies in solutions of the novel amine 4-(diethylamine)-2-butanol (DEAB), at various CO2 loadings (0-0.8 mol of CO2/mol of amine) and amine concentrations (0.52-1.97 M), were determined by C-13 nuclear magnetic resonance (NMR) spectroscopy. In addition, the dissociation constant K of DEABH(+) was determined at 24.5, 35, and 45 degrees C using a pH meter. The ion speciation plot, which contains various sets of concentrations of DEAB, protonated DEAB, bicarbonate, and carbonate, was successfully generated. Because DEAB is a novel solvent, this is the first time that the ion speciation plots of the DEAB-CO2-H2O system have been developed. It is also the first time that the C-13 NMR calibration technique was applied to develop the vapor-liquid equilibrium (VLE) model for an amine-CO2-H2O system. The results obtained from the present work can be a great help for the further analysis of the DEAB VLE model, as well as CO2 absorption and kinetics studies. Furthermore, it was found that the novel C-13 NMR calibration technique developed in this work provides higher accuracy than the conventional technique.