Abstract:

The organic amine aqueous solution absorption method is one of the most commonly used and mature methods for CO₂ capture, but key issues such as high regeneration energy consumption and severe degradation of the absorbent hinder its large-scale promotion and application. Water as a co-solvent in this technology is considered to be the weak point because of its large specific heat capacity and enthalpy of vaporization. These associated energy consumption takes up about 60% of the total energy for CO₂ desorption. The replacement of the strong polar water using organic solvents to develop non-aqueous absorbents has potential to reduce the regeneration energy consumption, degradation as well as equipment corrosion. Therefore, non-aqueous absorbents have attracted much attention in recent years. Research on the kinetics of CO₂ absorption by amines in organic solvents is helpful to understand the reaction mechanism and the effect of different structures or types of amines and co-solvents on the reaction kinetics, and also to design the CO₂ absorption process from the lab to industry. In this review, possible reaction mechanisms in non-aqueous solvents are summarized, and the typical experimental methods and principles for reaction kinetics reported in the literature are introduced. Research works and results on the kinetic properties for amine systems with various organics in the open literature are summarized and remarked. Moreover, further analysis on the correlation between solvent characteristics and the collected kinetic data is conducted. It has been found that roughly linear relationships between solvent characteristics and the reaction order and kinetic parameters are presented. For a specific amine, the second-order rate constant increases as increasing the solubility parameter of the co-solvents. However, the partial reaction order with respect to the primary and secondary amines increases with the increasing solvent polarity. Finally, some further research directions for reaction kinetics of CO₂ absorption in non-aqueous solvents are proposed based on critical analysis of the existing research.

Key words: absorption, amines, non-aqueous solvent, carbon dioxide (CO₂) capture, reaction kinetics

摘要：

有机胺水溶液吸收法是CO₂捕集最常用且成熟的方法之一，但是再生能耗高和吸收剂严重降解等关键问题阻碍了其大规模推广和应用。采用有机溶剂代替强极性水溶剂构建的非水吸收剂体系，在降低能耗方面具有巨大潜力，在近年来受到格外关注。非水吸收剂的CO₂吸收动力学研究有助于了解吸收过程的反应机理以及不同有机胺和溶剂类型对反应动力学的影响。本文从有机胺在非水溶剂中的反应机理出发，介绍了CO₂吸收动力学研究的典型实验方法和原理，系统评述了采用不同结构的有机胺在不同溶剂体系中吸收CO₂的动力学研究进展，深入分析了溶剂特性与胺的反应级数和反应动力学常数之间的关联性，并指出了普遍的规律性特征即有机伯胺和仲胺的反应级数随溶剂极性的降低而增大，反应速率常数随着溶剂的溶解度参数增大而呈现近似线性变化。在分析目前动力学研究中存在的问题基础上，对今后非水体系动力学的研究方向进行了展望。

关键词: 吸收, 有机胺, 非水吸收剂, 二氧化碳捕集, 反应动力学