278615 CO2 Absorption in Aqueous Alkanolamine Systems : CO2 Concentration and Henry Constant Determination

Wednesday, October 31, 2012: 10:10 AM
408 (Convention Center )
Elise Provost, Vanessa Gonzalez and Walter Fürst, UCP, ENSTA ParisTech, Paris, France

For both energy and environmental purposes, the removal of acid gases such as carbon dioxide (CO2) is involved in numerous processes such as natural gas treatment, as well as in petroleum refining, coal gasification, and hydrogen production. For such purification, reactive absorption with aqueous solutions of alkanolamines remains the most mature and widely implemented industrial technology.

Accurate understanding and modeling of the transfer occurring during the carbon dioxide absorption in alkanolamine solutions is of vital importance for optimizing the design of absorption units and reducing the absorber size, especially when high CO2 loading are achieved.  For the reason, knowing the concentration of molecular CO2 cCO2, the transferring species, is crucial. Because CO2 reacts with the solvent to form HCO3-, CO32- and carbamate if a primary or secondary amine is used, cCO2 cannot be simply deduced from VLE measurements. A thermodynamic modeling is needed, and the Henry constant of molecular CO2 is deduced from the N2O analogy. An original experimental device has been developed allowing the direct measurement of cCO2 [1]. In this work, original measurement of cCO2 and HCO2 are presented for the CO2 loaded following systems (water + methyldiethanolamine MDEA), (water + MDEA + diethanolamine DEA), (water + DEA + 2-Amino-2-Méthyl-1-Propanol AMP). Differences are observed with the values deduced from the N2O analogy or predicted using electrolyte NRTL.

[1] Anas Archane, Walter Fürst and Elise Provost, Influence of Poly(ethylene oxide) 400 (PEG400) on the Absorption of CO2 in Diethanolamine (DEA)/H2O Systems, JCED, 2011 56(5) 1852-1856

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