On the Acceleration of CO2 Reaction with N-Ethyldiethanolamine in Aqueous Solutions by the Addition of Promoters

Focusing on renewable resources, such as ethanol, for producing CO2-capturing solvents can stimulate a big change in the gas purification industry by creating a smaller environmental footprint. One such solvent showing great potential is the tertiary amine N-ethyldiethanolamine (EDEA). In this work, the reaction kinetics of the CO2-EDEA system in aqueous solutions (2-3 M) was determined from the absorption rate measurements in a stirred cell reactor under fast pseudo-first order conditions. We discovered that EDEA reacts with CO2 faster (rate constant k(EDEA) = 19 M-1 s(-1) at 303 K) than other tertiary amines, such as N-methyldiethanolamine (MDEA), N-propyldiethanolamine (PDEA), and N-butyldiethanolamine (BDEA). When the performance of different absorption promoters in aqueous EDEA solutions was tested, it was found that piperazine (PZ) was more effective than monoethanolamine (MEA) and diethanolamine (DEA). Therefore, the influence of PZ on the equilibrium and kinetic characteristics of aqueous EDEA solutions was investigated.