Monoethanolamine Degradation: O2 Mass Transfer Effects under CO2 Capture Conditions

This study examines the rate of oxidative degradation of MEA under conditions typical of a CO2 capture process. Experiments examined the effects of amine concentration, CO2 loading, O2 concentration, and agitation rate at 55 °C. Degradation rates were quantified by measuring the rate of NH3 evolution from the amine solutions using FT-IR analysis. Results show that degradation rates are controlled by the rate of physical absorption of O2 and NH3 evolution rates ranged from 0.2 to 8.0 mM/h. Previous studies were re-examined and compared to the current study and appear to have been performed under conditions that were mass transfer limited. This would indicate the previous literature values for degradation kinetics were actually O2 absorption rates. An estimate of the degradation rate for a CO2 absorber was made assuming the degradation was controlled by the rate of O2 absorption and was shown to be equal to or less than values reported in the literature.