Oxidative Degradation of Monoethanolamine

Oxidative degradation of monoethanolamine (MEA) was studied at 55 °C, 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.