Thermodynamic analysis of carbamate formation and carbon dioxide absorption in N-methylaminoethanol solution. (1st January 2021)

• Record Type: Journal Article
• Authors: Xiao, Min; Zheng, Wenchao; Liu, Helei; Luo, Xiao; Gao, Hongxia; Liang, Zhiwu
• Is Part Of: Applied energy. Volume 281(2021)
• Publication Date: 2021-01-01
• Subjects: CO2 capture -- Amine absorbent -- Thermodynamic analysis -- Modeling -- Reaction heat -- Molecular structure; Power (Mechanics) -- Periodicals; Energy conservation -- Periodicals; Energy conversion -- Periodicals; 621.042
• DOI: 10.1016/j.apenergy.2020.116021
• Languages: English
• ISSNs: 0306-2619

Abstract

Highlights: The CO2 absorption mechanism in MAE solution is investigated. The mild steric hindrance in MAE destabilizes carbamate and boosts bicarbonate formation. The reaction heat and CO2 absorption/desorption energy are obtained. A thermodyanmic model is established for equilibrium MAE-H2 O-CO2 system with average deviation of 4.2% The structure beneficial of MAE molecule is revealed to show favorable carbon capture properties. Abstract: Protonation and carbamate formation are critical reactions for CO2 capture using amine-based absorbents which impact both CO2 absorption and amine regeneration. In this regard, thermodynamic analysis towards CO2 absorption in N -methylaminoethanol solution is carried out with specific attention to the corresponding protonation and carbamate formation reactions. The CO2 absorption mechanism is investigated with the acquisition of reaction equilibrium constant and heat of reaction. CO2 absorption performance of N -methylaminoethanol solution was evaluated in terms of CO2 loading and solution pH. A thermodynamic model was then developed to mathematically describe the investigated system and make prediction on equilibrium CO2 solubility, species profiles, and absorption/regeneration heat. Results show that the average relative deviation of equilibrium CO2 solubility calculated from the is 4.2%. The predictive species profile and CO2 absorption heat of N -methylaminoethanol solution indicates less energy cost to desorb CO2 . This is in line with the relative unstable N -methylaminoethanol carbamate formation and consequential conversion to (bi)carbonate. The position of N -methylaminoethanol as a potential absorbent in amine based carbon capture is shown in terms of chemical reaction constants, equilibrium CO2 solubility, second order rate constant ( k2 ), and p Ka .