13C-NMR study of acid dissociation constant (pKa) effects on the CO2 absorption and regeneration of aqueous tertiary alkanolamines

Kogoro Hayashi, Yukio Furukawa, Hiroshi Sato, Yasuro Yamanaka

Research output: Contribution to journalConference article


We have studied the formation rates of chemical species such as 2-/HCO3 -, amine/protonated amine, and carbonate/protonated carbonate in the course of CO2 absorption at room temperature and concentration changes after CO2 release upon heating at 93 °C for 30 min for aqueous solutions of 12 kinds of tertiary alkanolamines using 13C-NMR spectroscopy. A positive linear correlation was found between the CO2 capture rates of alkanolamines having a normal hydroxyalkyl group and their pKa values. The CO2 capture rates of alkanolamines having a branched hydroxyalkyl group were lower than those in this relationship. The CO2 release amount of each tertiary amine increased with decreasing pKa, as a general trend. Nethyldiethanolamine (EDEA) showed the largest CO2 release amount and a moderately high rate of CO2 absorption.

Original languageEnglish
Pages (from-to)1876-1881
Number of pages6
JournalEnergy Procedia
Publication statusPublished - 2014 Jan 1
Event12th International Conference on Greenhouse Gas Control Technologies, GHGT 2014 - Austin, United States
Duration: 2014 Oct 52014 Oct 9


  • C-NMR
  • Acid dissociation constant
  • Ccs
  • Tertiary amine

ASJC Scopus subject areas

  • Energy(all)

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