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Degradation of alkanolamine blends by carbon dioxide

Authors

  • Olukayode Fatai Dawodu,

    1. Department of Chemical Engineering, The University of British Columbia, 2216 Main Mall, Vancouver, BC V6T 1Z4
    Current affiliation:
    1. Michigan Consolidated Gas Company, Detroit, MI 48226, USA
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  • Axel Meisen

    Corresponding author
    1. Department of Chemical Engineering, The University of British Columbia, 2216 Main Mall, Vancouver, BC V6T 1Z4
    • Department of Chemical Engineering, The University of British Columbia, 2216 Main Mall, Vancouver, BC V6T 1Z4
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  • This paper is an extension of a presentation made at the 42nd Canadian Chemical Engineering Conference, Toronto, ON (1992).

Abstract

Aqueous solutions of MDEA, MDEA + DEA and MDEA + MEA containing 4.2 kmol/m3 total amine, were contacted with CO2 at a partial pressure of 2.58 MPa and temperatures ranging from 120 to 180°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.

Abstract

Des solutions aqueuses de MDEA, MDEA + DEA et MDEA + MEA contenant 4,2 kmol/m3 d'amines au total ont été mises en contact avec du CO2 à une pression partielle de 2,58 Mpa et des temperatures comprises entre 120 et 180°C, dans un réacteur en acier inoxydable discontinu. Les produits de réaction comprennent les composés connus de dégradation des amines ainsi que des produits issus des interactions secondaires dans les mélanges d'amines. La vitesse de dégradation est du premier ordre dans les amines et, en ordre d'importance, suit la séquence MDEA < MEA < DEA. De plus, la constante de vitesse pour le MDEA est indépendante du degré de substitution des amines et des constituants du mélange. Sur le plan pratique, les mélanges de MDEA + DEA demanderaient un apport fréquent en DEA pour maintenir l'efficacité du traitement.

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