Oxidative degradation of monoethanolamine

Oxidative degradation of monoethanolamine (MEA) was studied at 55 degreesC, typical of absorbers for CO2 removal from flue gas. The rate of evolution of NH3, which was indicative of the overall rate of degradation, was measured continuously in a batch system sparged with air. Dissolved iron from 0.0001 to 1 mM yielded oxidation rates from 0.37 to 2 mM/h in MEA solutions loaded with 0.4 mol CO2/mol MEA. Ethylenediaminetetraacetic acid (EDTA) and N,N-bis(2-hydroxyethyl)glycine effectively decreased the rate of oxidation in the presence of iron by 40-50%. Ferrous caused oxidation in unloaded MEA with stoichiometry from 0.1 to 0.33 mol NH3/mol Fe2+. Fe2+ from 0.0001 to 3.2 mM yielded rates from 0.12 to 1.1 mM/h. Ferric did not appear to catalyze oxidation in unloaded MEA.