Experimental Measurement of Carbon Dioxide Solubility in Aqueous N-Methyldiethanolamine + 2-(2-Aminoethylamino) Ethanol + Sulfolane and Diethanolamine + 2-(2-Aminoethylamino) Ethanol + Sulfolane Hybrid Solvents at Various Temperatures and High Pressure

Abstract

The sets of vapor–liquid equilibrium (VLE) data for CO2 solubility in a combination of (N-methyldiethanolamine (MDEA) + 2-(2-aminoethylamino) ethanol (AEEA)) and (diethanolamine (DEA) + AEEA) as a chemical solvent blended with sulfolane as a physical solvent are acquired at 313.15–343.15 K within the CO2 partial pressure range up to 5600 kPa. The measurements are fulfilled for two different hybrid solvents of MDEA + AEEA + sulfolane with the weight compositions of (20–10–10) wt % and (20–10–20) wt % and a mixed solvent of DEA + AEEA + sulfolane with (20–10–10) wt %. It is deduced that CO2 loading was enhanced by substituting the MDEA with DEA, diminishing the temperature, and raising the pressure. Besides, increasing the sulfolane concentration in the aqueous system of MDEA + AEEA + sulfolane leads to enrichment in the effectiveness of the solution in CO2 absorption in the high loading region. In contrast, at low pressures, it adversely affects the acid gas loading. Moreover, it was displayed that at the same total mole of alkanolamines and sulfolane, the CO2 solubilities of AEEA + sulfolane and AEEA + MDEA + sulfolane are higher than those of AEEA + MDEA + sulfolane and MDEA + sulfolane, respectively. Therefore, it could be claimed that AEEA presents a better performance in CO2 capturing than MDEA. Besides, it was demonstrated that AEEA + sulfolane represents a higher capability in CO2 elimination than DEA + AEEA + sulfolane. Thus, the ability of DEA to remove CO2 is lesser than AEEA. Altogether, the degree of alkanolamines’ selectivity toward CO2 is found as AEEA > MDEA > DEA.