CO2 Capture Using Aqueous Potassium Carbonate Promoted by Ethylaminoethanol: A Kinetic Study

Abstract

Kinetics of absorption of CO2 in an aqueous potassium carbonate (K2CO3) promoted by ethylaminoethanol (EAE) solution (hereafter termed as APCE solvent) was investigated in a glass stirred cell reactor by employing a fall in pressure technique. The reaction chemistry associated with the CO2–APCE solvent system was described by the zwitterion mechanism. The solubility and diffusivity of CO2 in the APCE solvent were experimentally determined at different experimental conditions. Furthermore, the effect of the initial EAE concentration (0.6–2 kmol/m3) and reaction temperature (303–318 K) on the rate of absorption of CO2 was studied in detail. The experimental findings show that with the increase in the EAE concentration and reaction temperature, the rate of CO2 absorption in the APCE solvent also increases considerably. Kinetic measurements further confirm that the absorption of CO2 in the APCE solvent belongs to the fast reaction regime with first-order kinetics with respect to EAE and first-order kinetics with respect to CO2. Due to the addition of EAE as a promoter in an aqueous K2CO3, significant improvement in the rate of absorption of CO2 was realized. The rate constant (k2) for the CO2–APCE solvent system was observed to be higher as compared to monoethanolamine (MEA) promoted aqueous K2CO3. For instance, k2 for the absorption of CO2 in the APCE solvent was observed to be equal to 45540 m3/kmol·s at 318 K. Furthermore, the activation energy for the CO2–APCE solvent system was estimated to be 81.7 kJ/mol. The lumped parameter, , where HCO2 is solubility of CO2 and DCO2 is diffusivity of CO2 in the APCE solvent, was calculated based on the kinetic measurements and observed to be equal to 1.2 × 10-6 kmol1/2/m1/2·s·kPa