The present study analyzes the features of chemical CO₂ absorption using tertiary amine solvents by comparing the absorption performance and electrical properties between methyl-di-ethanolamine (MDEA) and tri-ethanolamine (TEA) systems. The results are mostly attributed to the different structures of the two amine molecules. Absorption performance is significantly affected by the molecular structure and water concentration in the amine solution. The absorption performance of the MDEA system is better than that of TEA, which is basically ascribed to the MDEA molecule's more asymmetric and irregular shape than that of TEA, which thus enhances the catalytic activity of MDEA and the reactivity of the −OH moiety in water. The difference of electrical properties such as ionic conductivities (ICs) of the two protonated amines and real ionic activity coefficients (RIAC) between the two systems might be also caused by the different molecular structures of the two amines. The IC of protonated MDEA is estimated to be 23.70% higher than that of protonated TEA, because of the higher ionic mobility and charge density of MDEA. The RIAC of the MDEA system is higher than that of TEA, which is explained by the different physicochemical interactions between the molecules in the two systems. Since water is one of the reactants in the absorption, its concentration in solution significantly affects the results of the systems. In addition, the absorption using tertiary amine is a base-catalyzed reaction, and thus variations of the overall absorption rate follow a parabolic curve. Therefore, it is maximized to be 14.2 and 9.8 mmol CO₂·L⁻¹·min⁻¹ in the 15 wt% MDEA and TEA solutions, respectively. Finally, the correlated equations for in situ estimation of chemical absorption capacity by electrical conductivity measured during the absorption are derived in the two systems. © 2021 The Authors. Greenhouse Gases: Science and Technology published by Society of Chemical Industry and John Wiley & Sons, Ltd.

中文翻译：

---

甲基二乙醇胺与三乙醇胺溶液体系CO2吸收性能比较及胺分子分析

本研究分析了化学CO ₂的特征通过比较甲基二乙醇胺 (MDEA) 和三乙醇胺 (TEA) 系统之间的吸收性能和电学性质，使用叔胺溶剂进行吸收。结果主要归因于两种胺分子的不同结构。吸收性能受胺溶液中分子结构和水浓度的显着影响。MDEA体系的吸收性能优于TEA，这基本上归因于MDEA分子比TEA更不对称和更不规则的形状，从而增强了MDEA的催化活性和-OH部分在水中的反应性. 两种质子化胺的离子电导率 (IC) 和实际离子活度系数 (RIAC) 等电学性质的差异也可能是由两种胺的不同分子结构引起的。由于 MDEA 具有更高的离子迁移率和电荷密度，因此质子化 MDEA 的 IC 估计比质子化 TEA 高 23.70%。MDEA 系统的 RIAC 高于 TEA，这是由两个系统中分子之间不同的物理化学相互作用来解释的。由于水是吸收过程中的反应物之一，它在溶液中的浓度会显着影响系统的结果。此外，使用叔胺的吸收是碱催化反应，因此总吸收率的变化遵循抛物线曲线。₂ ·L ^-1 ·min ^{-1 分别}在15wt% MDEA和TEA溶液中。最后，在两个系统中导出了通过在吸收过程中测量的电导率原位估计化学吸收能力的相关方程。© 2021 作者。Greenhouse Gases: Science and Technology由化学工业协会和 John Wiley & Sons, Ltd. 出版。