Secondary amines for CO2 capture: A kinetic investigation using N-ethylmonoethanolamine

N-ethylmonoethanolamine (EMEA), a secondary alkanolamine linked to an ethyl group, represents an especially promising absorbent for CO2 capture, because it can be prepared from renewable resources. Up to now, there is no reliable information on the reaction between CO2 and EMEA in the literature. In this work, the reaction mechanism and kinetics were investigated using a stirred-cell reactor at 298, 303, and 308 K. The reaction pathway was described using both the zwitterion and the termolecular mechanism. From our kinetic data at low amine concentration (0.02–0.1 M), we deduced that the absorption process occurs in the fast reaction regime with second-order kinetics for EMEA and first-order kinetics for CO2. Besides, a comparison with the efficacy of two other secondary amines, diethanolamine (DEA) and diisopropanolamine (DIPA) was performed, and it was found that the absorption rate in aqueous EMEA was faster than that in DEA and DIPA at high amine concentration (0.5–2 M). Thus, the performance of EMEA as a CO2 absorbent appears encouraging.

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• Kinetics of the CO2 reaction with N-ethylmonoethanolamine was studied.
• Reaction is of the second order in N-ethylmonoethanolamine concentration.
• N-ethylmonoethanolamine reacts faster than diethanolamine and diisopropanolamine.