Carbamate Stability Measurements in Amine/CO2/Water Systems with Nuclear Magnetic Resonance (NMR) Spectroscopy

NMR experiments were carried out for 30 mass % aqueous solutions of monoethanolmine (MEA), ethylenediamine (EDA) and piperazine (PZ) at 25 °C. To distinguish between the amine/protonated amine and bicarbonate/carbonate pairs, an earlier method developed for primary amine (2-amino-2-methyl-1-propanol) was implemented. The amine protonation constant, the dissociation constant of carbonic acid from literature, and pH measurements for different ionic strengths, were all employed and the data were correlated with ionic strength.