US EPA

7449893 

Journal Article 

NMR Studies of Amine Species in MEA-CO2-H2O System: Modification of the Model of Vapor-Liquid Equilibrium (VLE) 

Fan, G; Wee, AGH; Idem, R; Tontiwachwuthikul, P 

2009 

Yes 

Industrial and Engineering Chemistry Research
ISSN: 0888-5885
EISSN: 1520-5045 

48 

5 

2717-2720 

English 

10.1021/ie8015895 

WOS:000263725200050 

Speciation studies in aqueous monoethanolamine (MEA) solution at different CO 2 loadings have been conducted via nuclear magnetic resonance (NMR) spectroscopy. The results showed that the diagnostic peaks corresponding to the MEA and the protonated amine (MEAH+) observed by 1H NMR spectroscopy were gradually shifted downfield, whereas the corresponding 13C peaks were shifted upfield as the CO 2 loading increased. Quantitatively, the molar fraction of the carbamate was obtained by integration of the relevant peak areas in the 1H NMR spectra while the molar fractions of free MEA and MEAH+ were determined according to the MEAH + dissociation constant and pH value of the solution. Furthermore, as the CO 2 loading increased, the fraction of free MEA dropped steadily, while the ratio of carbamate and MEAH+ increased monotonically. The molar ratio of the carbamate reached its maximum at a CO 2 molar loading of 0.5. The data obtained from this study have led us to propose a modification to the current vapor-liquid equilibrium (VLE) model for this system. © 2009 American Chemical Society. 

Dissociation constants; H nmr spectroscopies; H nmr spectrum; Molar fractions; Molar ratios; Monoethanolamine; Nmr studies; Peak areas; pH values; Protonated amines; Vapor-liquid equilibrium; Amines; Dissociation; E-learning; Liquids; Loading; Nuclear magnetic resonance; Organic compounds; Phase equilibria; Sodium compounds; Vapors; Nuclear magnetic resonance spectroscopy