Kinetics of Absorption of Carbon Dioxide in Aqueous Solution of Ethylaminoethanol Modified with N-methyl-2-pyrolidone

Abstract

In this paper, kinetics of absorption of CO2 in an aqueous ethylaminoethanol (EAE) and formulated solvent (aqueous blend of EAE and N-methyl-2-pyrrolidone (NMP)) was studied in a stirred cell reactor by using a fall in pressure technique. The reaction pathways for CO2–aqueous EAE system were comprehensively described using both zwitterion and termolecular mechanisms. The physico-chemical properties such as density (ρ) and viscosity (μ) of aqueous EAE and formulated solvent and the solubility () and diffusivity of CO2 () in these solvents were estimated experimentally. The reactive absorption of CO2 in an aqueous EAE was observed to be first order with respect to both CO2 and EAE concentrations. Addition of NMP in aqueous EAE enhances the by 40%, which ultimately results into higher CO2 absorption rates in formulated solvent (∼20% higher) compared to that of the aqueous EAE. Effect of concentration of EAE (0.5 to 2 kmol/m3) and temperature (303 to 318 K) on CO2 absorption kinetics was studied in detail and it was realized that the rate of absorption of CO2 in aqueous EAE and formulated solvent was significantly affected by the change in these parameters. The findings obtained during the temperature dependency study further indicates that the activation energy of the absorption of CO2 in aqueous EAE (80.2 kJ/mol) was relatively lower in comparison with the activation energy of the absorption of CO2 in formulated solvent (88.95 kJ/mol). The overall reaction of CO2 with the formulated solvent could be regarded as the reaction of CO2 with aqueous EAE in parallel with the reaction between CO2 and aqueous NMP.