Kinetics of the Oxidative Degradation of CO2 Loaded and Concentrated Aqueous MEA-MDEA Blends during CO2 Absorption from Flue Gas Streams

A study of empirical kinetic models of the degradation of MEA and MDEA in MEA-MDEA-H2O-O2, MEA-MDEA-H2O-CO2, and MEAMDEA-H2O-O2-CO2 systems was conducted in a stirred cell reactor at temperatures in the range of 328-393 K, overall amine concentration of 7-9 mol/L, MEA/MDEA ratio (r) in the range of 2.5:1-9:1, CO2 loading () in the range of 0.4 and 0.43 mol/mol total amine, and a CO2 or O2 pressure of 250 kPa. The results showed that higher total amine concentrations and temperatures resulted in higher rates of degradation, whereas higher CO2 loadings had the opposite effect. The results, however, showed that the rates of degradation of MEA and MDEA in the MEA-MDEA-H2O-CO2 system were practically zero. On the other hand, both the MEA-MDEAH2O-O2 and the MEA-MDEA-H2O-CO2-O2 systems had rates greater than zero.