This study examines degradation of five tertiary polyamines (di-and triamines) in the presence of CO 2 or O 2 . They were chosen to identify the impact of alkyl chain length between amine functions. Degradation of aqueous amine solutions was evaluated at 140 °C under CO 2 or air pressure (2 MPa) in stainless steel batch reactors for 15 days. At the end of the run, most degradation products were identified by gas chromatography (GC)/mass spectrometry; amounts of remaining amine and its degradation products were determined with a quantitative GC method. The main degradation mechanisms are proposed, and some structure-properties relationships are established.

Degradation of 22 compounds was evaluated in stainless steel batch reactors at 140 °C for 14 days under a pressure of 0.5 MPa (mixture of 75% CO2, 20% N2, and 5% O2). For each run, two corrosion coupons, one carbon steel (XC38) and one stainless steel (304Ti), were immersed in aqueous solutions of amines to determine corrosion due to degraded solutions. Two additional coupons were put in the vapor phase above solutions. At the end of the run, corrosion rates were evaluated through weight-loss measurements. The amounts of remaining starting material were determined with a quantitative gas chromatography method. Corrosion and degradation data were compared with those of a benchmark molecule (MEA, monoethanolamine), tested under the same conditions. Results indicate that some molecules are less corrosive and have a better chemical stability than MEA. In addition, a quantitative structure property relationship (QSPR) model was built that can be applied to predict compound degradation.

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