离子液体吸收CO_(2)及其机理研究进展

Research progress of CO_(2) absorption and mechanism by ionic liquids

鉴于离子液体(Ionic Liquids,ILs)的低挥发和低腐蚀性的优点,近年来不少学者利用ILs替代传统碱液捕集和分离CO_(2)。介绍了近年来ILs-CO_(2)的物理和化学吸收机理,并分析了氨基功能化ILs和非质子杂环(AHA)ILs吸收CO_(2)前后黏度变化规律,以及用水降黏后ILs水溶液对CO_(2)吸收性能的影响。综合分析ILs-CO_(2)的相互作用,发现增强ILs-CO_(2)的范德华相互作用(如色散力、静电力作用)有助于物理吸收CO_(2);提高官能团碱度、合理利用离子间质子转移有助于化学吸收CO_(2)。在吸收CO_(2)后,氨基功能化ILs黏度多呈增加趋势;而AHA ILs形成氢键网络的可能性较小,因此黏度变化不明显甚至有下降趋势。水作为稀释剂可有效降低氨基功能化和AHA ILs黏度,低压时仍然能够通过化学吸收捕集CO_(2)。对于ILs-H_(2)O复配体系,可综合考虑降低温度、提高压力、调节ILs-H_(2)O复配比例,协同化学吸收和物理吸收机制来提高CO_(2)吸收性能。

This paper elaborates on recent global research papers on the physical and chemical absorption mechanism of ILs-CO_(2).Besides,this paper researches the viscosity changes of Amino-functionalized ILs and AHA ILs(Aprotic Heterocyclic Anion ILs)on their absorbing CO_(2),also analyzes the impact of ILs viscosity reduction with water on the performance of absorbing CO_(2).Observations and analysis on the interactions of ILs and CO_(2) demonstrate that(1)enhancing the van der Waals interaction of ILs-CO_(2)(such as dispersion force and electrostatic force)can strengthen ILs’ability to physically absorbing CO_(2);(2)increasing the basicity of functional groups and better utilization of proton transfer among ions can improve ILs’ability of chemically absorbing CO_(2).In amino-functionalized ILs,a larger number of amino groups in anions and cations helps to absorb CO_(2).Also,the higher basicity of anions,the more CO_(2) AHA ILs can be absorbed.After absorbing CO_(2),the viscosity of amino-functionalized ILs from the majority of observations is increased.However,due to the low probability of forming a hydrogen bond network in AHA ILs,their viscosity has insignificant changes or even dropped on absorbing CO_(2).Water as a diluent can significantly reduce the viscosity of the amino-functionalized ILs and AHA ILs,and it can still capture CO_(2) through chemical absorption at low pressure.In the ILs-H_(2)O complex system,a higher temperature can accelerate the CO_(2) absorption of the solution,and reduce the CO_(2) solubility.Heavier pressure can improve CO_(2) absorption performance.Therefore,the complex system can be optimized to improve CO_(2) absorption performance by tuning those parameters including the number of amino groups,basicity,temperature,pressure,and ILs-H_(2)O ratio,and also by coordinating the chemical and physical absorption mechanism.The conclusion is that a positive prospect and bright future can be expected in the application of ILs with high solubility,easy desorption,low viscosity,and related process safety technologies.