Absorption data and modeling of carbon dioxide in aqueous blends of bis(2-hydroxyethyl)methylamine (MDEA) and 2,2-iminodiethanol (DEA): 25 % MDEA + 25 % DEA and 30 % MDEA + 20 % DEA

Abstract : This paper presents loading data for the solvent absorption of carbon dioxide into two amine blends. The absorption data were measured using a static analytic apparatus. The blends investigated were 25 % MDEA + 25 % DEA + 50 % H 2O and 30 % MDEA + 20 % DEA + 50 % H 2O (by mass). A few data measurements for carbon dioxide absorption are also presented for the amine blend comprising 50 % DEA + 50 % H 2O. Different carbon dioxide partial pressures were studied, ranging from approximately (0.05 to 1.05) MPa. The system pressure was manipulated by the addition of nitrogen gas. System pressures ranged from approximately (0.5 to 1.5) MPa. Solvent absorption was studied at (362.1 and 412.1) K. The data measured are presented and discussed with regard to CO 2 loading curves and partition coefficient values. The data were modeled using the Posey-Tapperson-Rochelle model and the Deshmukh-Mather model. The experimental results indicate that increasing the temperature reduces the absorption capacity of the solvents studied. The amine blend comprising 25 % MDEA + 25 % DEA + 50 % H 2O showed the best loading performance of all of the solvents studied, including blended and single amine studies from literature at similar temperatures to that investigated in this study. This indicates that the blending of MDEA and DEA at higher solvent concentrations is beneficial in increasing carbon dioxide liquid loading in relation to carbon dioxide partial pressure, for a particular temperature. Of the models studied, the Deshmukh-Mather model provided better CO 2 loading predictions with errors as low as 0.05 % of the measured CO 2 loading, due to a more realistic account of the mechanism of reactive absorption and the associated interaction between the species involved.