Degradation alkanolamine blends by carbon dioxide

Aqueous solutions of MDEA, MDEA + DEA and MDEA + MEA containing 4.2 kmol/m(3) total amine, were contacted with CO2 at a partial pressure of 2.58 MPa and temperatures ranging from 120 to 180 degrees C, in a stainless steel batch reactor. The reaction products include the known degradation compounds of the amines as well as products formed from secondary interactions in the amine blends. The rate of degradation was first order in the amines and, in magnitude, followed the sequence MDEA < MEA < DEA. Furthermore, the rate constant for MDEA was independent of amine substitution level and blend constituents. From a practical standpoint, MDEA + DEA blends would require frequent DEA make-up to maintain treating efficiency.