Amine blends have been extensively studied as advanced solvents modification for CO₂ absorption. Due to the lack of knowledge on mechanism of amines interaction, reaction in blends was traditionally regarded as parallel reactions between CO₂ and different amines. In this work, the kinetics of CO₂ reaction with blends of two promising diamines, piperazine (PZ), N-(2-aminoethyl) ethanolamine (AEEA), were studied in a wetted wall column. The reaction rate constants of single amine were derived from kinetic data based on the zwitterion and termolecular mechanism for PZ and AEEA, respectively. It is interesting to find that the overall reaction rate of the blend is 12.0–28.1% lower than the calculated value through parallel reaction mechanism, which indicates the strong interaction between PZ and AEEA. A ‘zwitterion bridge’ reaction pathway was proposed as the microscopic mechanism of the interaction in the blend. Based on the kinetic models and experimental data, the interaction that PZ can promote the reaction in amines blend by transferring CO₂ to AEEA through the PZ-CO₂ intermediate was revealed. Besides, the interaction was proved to be a fast reaction with the reaction rate of same magnitude compared with the zwitterion hydrolysis reaction. The mechanisms of interaction between the two amines are further investigated through density functional theory (DFT). Results of simulation, in terms of activation energy and molecular geometry deformation, indicate that the PZ prefers a direct reaction with CO₂ rather than the reaction with the AEEA-CO₂ intermediate.

胺共混物已被广泛研究作为吸收CO _2的高级溶剂改性剂。由于缺乏有关胺相互作用机理的知识，传统上将共混物中的反应视为CO ₂与不同胺之间的平行反应。在这项工作中，CO ₂的动力学在湿壁柱中研究了与两种有前途的二胺（哌嗪（PZ），N-（2-氨基乙基）乙醇胺（AEEA））的混合物的反应。分别基于两性离子和PZ和AEEA的分子机理的动力学数据，得出了单胺的反应速率常数。有趣的是，共混物的总反应速率比通过平行反应机理计算的值低12.0–28.1％，这表明PZ与AEEA之间的相互作用很强。提出了“两性离子桥”反应途径作为共混物中相互作用的微观机理。基于动力学模型和实验数据，PZ可以通过PZ-CO ₂将CO ₂转移至AEEA来促进胺混合物中的反应中间被揭示。此外，与两性离子水解反应相比，该相互作用被证明是一种快速反应，反应速率相同。通过密度泛函理论（DFT）进一步研究了两种胺之间的相互作用机理。在活化能和分子几何变形方面的模拟结果表明，PZ更喜欢与CO ₂直接反应，而不是与AEEA-CO ₂中间体反应。