Study of Equilibrium Solubility, Heat of Absorption, and Speciation of CO 2 Absorption into Aqueous 2-Methylpiperazine (2MPZ) Solution

作者：Rui Zhang, Wusan Jiang, Zhiwu Liang, Xiao Luo, Qi Yang · 发表于：Industrial & Engineering Chemistry Research · 年份：2018 · DOI：10.1021/acs.iecr.8b03104 · 被引用次数：17 · 研究领域：Carbon Dioxide Capture Technologies、Membrane Separation and Gas Transport、Ionic liquids properties and applications

The CO 2 reaction rate in aqueous 2-methylpiperazine (2MPZ) solution was investigated in terms of the pseudo-first-order rate constant ( k 0 ) by using a stopped-flow apparatus with amine concentration ranges of 0.05–0.125 mol/L and the measuring temperature ranges of 293.15–313.15 K. The results show that the CO 2 reaction rate in the 2MPZ solution increased as the temperature and the amine concentration increases. The results also demonstrate that the 2MPZ has a faster reaction rate in terms of k 0 than 3-dimethylaminopropylamine, 3-diethylaminopropylamine, and monoethanolamine (MEA) but slower than that of PZ at the same amine concentration. The equilibrium solubility as an important absorption parameter for CO 2 capture also were measured at 298.15, 313.15, and 333.15 K with CO 2 partial pressures of 5–100 kPa, respectively, in 2 M 2MPZ solution. The results show that the CO 2 equilibrium solubility of 2MPZ increased as the CO 2 partial pressure increased but decreased as the temperature increased. The heat of CO 2 absorption in 2 M 2MPZ solution was estimated by using the Gibbs–Helmholtz equation, and the value (−70.9 kJ/mol) is similar to that of PZ but lower than that of MEA. Besides the conclusions stated above, the results of the 13 C NMR quantitative investigation suggest that 2MPZ can produce less carbamate and more bicarbonate than PZ at the same CO 2 loading.