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

- Reaction kinetics of 1-(2-HE)PRLD with CO2 is presented using stopped-flow technology.
- CO2 absorption heat of 1-(2-HE)PRLD is shown.
- The plot of the kinetics versus heat absorption is created.

The CO2 absorption 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 (ko) and second-order reaction rate constant (k2), obtained using the stopped-flow apparatus). CO2 equilibrium solubility and heat of CO2 absorption 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 CO2 solubility. The values of ko were then represented using the base-catalyzed hydration mechanism, which gave an acceptable AAD of 10%. In addition, Brønsted plots of k2 vs. pKa were developed to predict k2 using pKa values of various tertiary amines. In addition, the CO2 equilibrium solubility and CO2 absorption 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 CO2 equilibrium 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 CO2 absorption 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 CO2 capture. A correlation between kinetics and heat of CO2 absorption has been developed to guide the design of what can be considered to be ideal amine solvents for CO2 capture.