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

Kinetics of absorption of CO 2 in an aqueous potassium carbonate (K 2 CO 3 ) 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 CO 2 –APCE solvent system was described by the zwitterion mechanism. The solubility and diffusivity of CO 2 in the APCE solvent were experimentally determined at different experimental conditions. Furthermore, the effect of the initial EAE concentration (0.6–2 kmol/m 3 ) and reaction temperature (303–318 K) on the rate of absorption of CO 2 was studied in detail. The experimental findings show that with the increase in the EAE concentration and reaction temperature, the rate of CO 2 absorption in the APCE solvent also increases considerably. Kinetic measurements further confirm that the absorption of CO 2 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 CO 2 . Due to the addition of EAE as a promoter in an aqueous K 2 CO 3, significant improvement in the rate of absorption of CO 2 was realized. The rate constant ( k 2 ) for the CO 2 –APCE solvent system was observed to be higher as compared to monoethanolamine (MEA) promoted aqueous K 2 CO 3 . For instance, k 2 for the absorption of CO 2 in the APCE solvent was observed to be equal to 45540 m 3 /kmol·s at 318 K. Furthermore, the activation energy for the CO 2 –APCE solvent system was estimated to be 81.7 kJ/mol. The lumped parameter,, where H CO 2 is solubility of CO 2 and D CO 2 is diffusivity of CO 2 in the APCE solvent, was calculated based on the kinetic measurements and observed to be equal to 1.2 × 10 –6 kmol 1/2 /m 1/2 ·s·kPa.