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Title: Absorption of carbon dioxide into aqueous amine and amine/carbonate solutions
Author: Chan, H. M.
Awarding Body: University of Cambridge
Current Institution: University of Cambridge
Date of Award: 1980
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This work was carried out to investigate whether Marangoni convection would occur during the absorption of carbon dioxide into amine and amine/carbonate solutions in a packed column and a stirred cell in which the liquid was in turbulent flow regime and liquid surface was periodically and randomly renewed. In addition, the present investigation was extended to study the kinetics of the reaction of carbon dioxide with amine and amine/carbonate solutions and the effect of increased temperature (i.e. 25°C - 40°C) on the reaction rates and Marangoni convection in the above solutions in the stirred cell. By desorbing an inert tracer oxygen with the simultaneous absorption of carbon dioxide into amine and amine/carbonate solutions in the packed column and the stirred cell respectively, it was shown that the physical liquid-phase mass transfer coefficient was substantially increased by the CO2-amine and C02-amine/carbonate chemical abosrption processes. Hence, the occurrence of Marangoni convection in the liquid-phase in these two systems was confirmed. It was also observed that the intensity of Marangoni convection could be inhibited by the presence of stagnant film of contaminants in the packed column and completely suppressed in the stirred cell. Marangoni convection was found to be more pronounced in amine/carbonate solutions than in amine solutions of the same feed concentration of amine. The reasons for this behaviour was discussed. The intensity of Marangoni convection was also found to show a tendency of decrease with the increase of temperature. Under the present investigation condition, from the experimental results, the reaction of carbon dioxide with monoethanolamine (MEA) appeared to follow simple second-order chemical reaction kinetics. However, the rate of absorption of C02 into aqueous diethanolamine (DEA) solution was consistent with the kinetics reported by other workers who found the reaction being overall third order. Besides, the experimental results appeared to indicate that the reaction of carbon dioxide and DEA was catalysed by CO2 ion in DEA/carbonate solutions. The reaction rate constant for each of the systems mentioned was calculated. Finally, the values of the equilibrium constant, Keq, for MEA and DEA were determined at 25°C and 40°C respectively and were found to be in fairly good agreement with the corresponding values reported by previous workers.
Supervisor: Not available Sponsor: Not available
Qualification Name: Thesis (Ph.D.) Qualification Level: Doctoral
EThOS ID:  DOI: Not available