Analysis of solubility, absorption heat and kinetics of CO₂ absorption into 1-(2-hydroxyethyl)pyrrolidine solvent

The CO₂absorption performance of aqueous 1-(2-hydroxyethyl)pyrrolidine (1-(2-HE)PRLD) was studied with respect to kinetics (i.e., in terms of the pseudo-first-order rate constant (k_o) and second-order reaction rate constant (k₂), obtained using the stopped-flow apparatus). CO₂equilibrium solubility and heat of CO₂absorption were evaluated at the temperature range of 293–313 K in the 1-(2-HE)PRLD concentration range of 0.20–1.00 mol/L for kinetics and at 2 M for CO₂solubility. The values of k_owere then represented using the base-catalyzed hydration mechanism, which gave an acceptable AAD of 10%. In addition, Brønsted plots of k₂vs. pKa were developed to predict k₂using pKa values of various tertiary amines. In addition, the CO₂equilibrium solubility and CO₂absorption heat were obtained in this work. Based on a comparison with other amines such as MEA, MDEA and 1DMA2P, 1-(2-HE)PRLD showed better performance in terms of CO₂equilibrium solubility (DEAB > 1-(2-HE)PRLD > 1-(2HE)PP > 1DMA2P > MDEA > MEA > DEA), kinetics (MEA > DEA > DEAB > 1-(2-HE)PRLD > 1-(2-HE)PP > DMMEA > 1DMA2P > MDEA.) and CO₂absorption heat (MEA > DEA > MDEA > DEAB > 1-(2-HE)PRLD > 1-(2HE)PP > 1DMA2P). Therefore, 1-(2-HE)PRLD could be considered as a good alternative solvent for CO₂capture. A correlation between kinetics and heat of CO₂absorption has been developed to guide the design of what can be considered to be ideal amine solvents for CO₂capture.