Online NMR spectroscopic study of species distribution in MEA–H2O–CO2 and DEA–H2O–CO2

• DOI: 10.1016/j.fluid.2007.09.017
• Publication Date: 2007-10-02T07:31:00Z
• Authors: Wolfram Böttinger; Michael Maiwald; Hans Hasse
• Keywords: Diethanolamine

Quantitative online nuclear magnetic resonance (NMR) spectroscopy was used to study the species distribution in solutions of carbon dioxide (CO2) in aqueous N-methyldiethanolamine (MDEA), and MDEA + piperazine (PIP). The mass fraction of MDEA in the unloaded ternary solution was 0.2, 0.3, and 0.4 g/g. In quaternary solutions, the mass fraction of MDEA was 0.3 g/g, and that of PIP was 0.1 g/g. The temperature ranged from 293 K to 333 K, and the overall CO2 loading was up to 1.4 molCO2/molamine. For the measurements, a special apparatus was used that allowed the mixtures to be prepared gravimetrically and applied pressures up to 25 bar to keep the CO2 in solution. It was coupled to a 400 MHz NMR spectrometer by heated capillaries. Using both 1H and 13C NMR spectroscopy, quantitative information on the concentrations of the following species was obtained: amines, carbamates, bicarbonate, and CO2. Because of the fast proton transfer between molecular and protonated amines, only the sum of their concentrations...