Study of Equilibrium Solubility, NMR Analysis, and Reaction Kinetics of CO 2 Absorption into Aqueous N 1 , N 2 -Dimethylethane-1,2-diamine Solutions

作者：Wenchao Zheng, Wusan Jiang, Rui Zhang, Xiao Luo, Zhiwu Liang · 发表于：Energy & Fuels · 年份：2019 · DOI：10.1021/acs.energyfuels.9b03239 · 被引用次数：12 · 研究领域：Carbon Dioxide Capture Technologies、Phase Equilibria and Thermodynamics、Adsorption and Cooling Systems

The equilibrium solubility and kinetics of N 1, N 2 -dimethylethane-1,2-diamine (DMEDA), a new and potential diamine absorbent for CO 2 capture, have been investigated in this work. The equilibrium solubility of 2 M DMEDA solution was measured at 298.15–333.15 K and with CO 2 partial pressures of 5–100 kPa. The heat (−56.47 kJ/mol) of CO 2 absorption was obtained by the Clausius–Clapeyron equation. In addition, the NMR analysis further confirmed the formation of dicarbamate and that the reaction rate contribution by dicarbamate can be ignored, and showed the CO 2 absorption in the liquid phase can be divided into three regions as the CO 2 loadings increased. The pseudo-first-order rate constant ( k 0 ) of CO 2 absorption into aqueous DMEDA solution was then investigated at different amine concentrations (0.025–0.075 mol/L) and temperatures (293.15–313.15 K) with stopped-flow technology. The results show that the k 0 value in the DMEDA solution increases with the increase of temperature and amine concentration. The pseudo-first-order assumption, zwitterion mechanism, and termolecular mechanism were respectively applied to the DMEDA–CO 2 –H 2 O system. The results show that the predicted CO 2 absorption rate exhibits good agreement with the experimental data with absolute average deviations (AADs) of 3.66, 3.77, and 4.51% with respect to the pseudo-first-order assumption, zwitterion, and termolecular models, respectively.