CO2 absorption/desorption in aqueous DEEA/MDEA and their hybrid solutions with sulfolane

Abstract

CO2 absorption capacities in aqueous and hybrid solutions were investigated by applying a batch reactor under intermediate pressures up to 800 kPa. Tertiary alkanolamine of diethyl ethanol amine (DEEA), N-methyl di ethanol amine (MDEA), and physical solvent of sulfolane were used. Utilizing DEEA and sulfolane in the current research is considered as the first attempt to take the advantages of both chemical and physical solvents in CO2 capturing. The absorption capacities were increased by increasing the reactant concentration, pressure, and by decreasing the temperature. A higher absorption capacity was observed for the aqueous DEEA solution compared to the other solutions except in high pressures, in which the DEEA hybrid solution represented a higher capacity. Regeneration of the solutions by desorption at 80 °C revealed the effective role of the physical solvent (sulfolane) that yields higher regeneration efficiencies of absorption capacities for the hybrid solutions. The regeneration efficiencies of absorption capacity of the hybrid DEEA solution were in the range of 88.1%–99.1% while those efficiencies for the aqueous DEEA solution were in the range of 50–83.1%. These values for the hybrid and aqueous MDEA solutions were 93.4–98.8% and 85.5–94.2%, respectively. In conclusion, adding sulfolane to the aqueous DEEA solution significantly improved the absorption capacity of the regenerated solution.