The leading process for the post combustion capture (PCC) of CO 2 from coal-fired power stations and hence reduction in greenhouse gases involves capture by aqueous amine solutions. Of the reactions that occur in solution, which include CO 2 hydration, de-protonation of carbonic acid, amine protonation and carbamate formation, the protonation of the amine in the absorber and its subsequent de-protonation in the stripper involve the greatest enthalpy changes. In this study, protonation constants (reported as log 10 K prot) of selected series of primary, secondary and tertiary alkanolamines/amines over the temperature range 288-318 K are reported. Selected series studied involve primary, secondary and tertiary mono-, di- and tri-alkanolamines, secondary amines including heterocyclic species, and both -CH 2OH and -CH 2CH 2OH substituted piperidines. van't Hoff analyses have resulted in the standard molar enthalpies, ΔH mo, and molar entropies, ΔS mo, of protonation. Trends in ΔH mo are correlated with systematic changes in composition and structure of the selected series of amines/alkanolamines, while ΔH mo- ΔS mo plots generated linear correlations for the mono-, di-, and tri-alkanolamines, the -CH 2OH and -CH 2CH 2OH substituted piperidines, and the alkylamines. These relationships provide a guide to the selection of an amine(s) solvent for CO 2 capture, based on a greater difference in log 10 K prot between the absorber and stripper temperatures. © 2012 Elsevier Ltd. All rights reserved.
Fernandes, D., Conway, W., Wang, X., Burns, R., Lawrance, G., Maeder, M., & Puxty, G. (2012). Protonation constants and thermodynamic properties of amines for post combustion capture of CO 2. Journal of Chemical Thermodynamics, 51, 97–102. https://doi.org/10.1016/j.jct.2012.02.031