Absorption of Acid Gases: Evaluation of Thermodynamic and Kinetic Aspects of an Aqueous Solution of 2‑(2-Diethylaminoethoxy) Ethanol and 1,3-Dimethyl-2-imidazolidinone

The removal of CO2 and H2S from a gas by absorption with an aqueous alkanolamine solution is an energy-intensive process. The addition of a physical cosolvent might lower the regeneration energy but also affects the thermodynamics and kinetics of acid gas absorption. In this work, we study the impact on the thermodynamics and kinetics of CO2 and H2S absorption of the addition of 1,3-dimethyl-2-imidazolidinone (DMI) to the aqueous 2-(2-diethylaminoethoxy)ethanol (DEAE-EO) solvent. A comparison is made with the impact of DMI on an aqueous methyldiethanolamine (MDEA) solvent. In all cases, DMI reduced the solubility and the absorption rate of the acid gases. DMI also reduced the initial kinetic H2S/CO2 selectivity, although this effect seems much more pronounced in aqueous MDEA than in aqueous DEAE-EO. The equilibrium thermodynamic H2S/CO2 selectivity is higher in the presence of DMI.