TY - JOUR
T1 - Two-stage interaction performance of CO2 absorption into biphasic solvents
T2 - Mechanism analysis, quantum calculation and energy consumption
AU - Shen, Yao
AU - Chen, Han
AU - Wang, Junliang
AU - Zhang, Shihan
AU - Jiang, Chenkai
AU - Ye, Jiexu
AU - Wang, Lidong
AU - Chen, Jianmeng
N1 - Publisher Copyright:
© 2019 Elsevier Ltd
PY - 2020/2/15
Y1 - 2020/2/15
N2 - The CO2 capture capabilities of amine-based biphasic solvents have been extensively investigated. However, the mechanism of CO2 absorption into the biphasic solvents has not been adequately examined, even if it is very important for the solvent screening, composition optimization, efficiency improvement and heat duty reduction. In this work, a two-stage interaction mechanism is proposed through CO2 absorption performance, 13C nuclear magnetic resonance analysis, and quantum calculation. The experimental results and quantum calculation revealed that the shift of the absorption mechanism depended on the active amine group in the biphasic solvents. In the first stage, for a high concentration of the active amine group, a proton was transferred from zwitterion to tertiary amines with the primary amines as intermediates. The CO2 absorption rate was controlled by reaction kinetics, which resulted in a high absorption rate and inconspicuous phase change. In the second stage, for a low concentration of the active amine group, the thermodynamics-controlled absorption rate decreased sharply (by 65.2% for 1,4-butanediamine/N,N-dimethylcyclohexylamine) because the proton transferred from zwitterion to tertiary amines directly. Kinetic analysis revealed that, with an increase in the temperature from 298 to 333 K, the reaction rate constants increased by 285–362% at the first stage. However, the equilibrium constants decreased by 17.7–21.3% at the second stage. Taking both the kinetics and energy penalty into account, the triethylenetetramine/N,N-dimethylcyclohexylamine solution with a lean loading of 0.4 mol mol−1 is promising to achieve the high absorption rate and low-energy consumption.
AB - The CO2 capture capabilities of amine-based biphasic solvents have been extensively investigated. However, the mechanism of CO2 absorption into the biphasic solvents has not been adequately examined, even if it is very important for the solvent screening, composition optimization, efficiency improvement and heat duty reduction. In this work, a two-stage interaction mechanism is proposed through CO2 absorption performance, 13C nuclear magnetic resonance analysis, and quantum calculation. The experimental results and quantum calculation revealed that the shift of the absorption mechanism depended on the active amine group in the biphasic solvents. In the first stage, for a high concentration of the active amine group, a proton was transferred from zwitterion to tertiary amines with the primary amines as intermediates. The CO2 absorption rate was controlled by reaction kinetics, which resulted in a high absorption rate and inconspicuous phase change. In the second stage, for a low concentration of the active amine group, the thermodynamics-controlled absorption rate decreased sharply (by 65.2% for 1,4-butanediamine/N,N-dimethylcyclohexylamine) because the proton transferred from zwitterion to tertiary amines directly. Kinetic analysis revealed that, with an increase in the temperature from 298 to 333 K, the reaction rate constants increased by 285–362% at the first stage. However, the equilibrium constants decreased by 17.7–21.3% at the second stage. Taking both the kinetics and energy penalty into account, the triethylenetetramine/N,N-dimethylcyclohexylamine solution with a lean loading of 0.4 mol mol−1 is promising to achieve the high absorption rate and low-energy consumption.
KW - Biphasic solvent
KW - CO capture
KW - Chemical absorption
KW - Energy penalty
KW - Quantum calculation
KW - Reaction mechanism
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U2 - 10.1016/j.apenergy.2019.114343
DO - 10.1016/j.apenergy.2019.114343
M3 - Article
AN - SCOPUS:85076635016
SN - 0306-2619
VL - 260
JO - Applied Energy
JF - Applied Energy
M1 - 114343
ER -