双位点功能化离子液体碳捕集过程中抑制与协同作用的研究

Carbon dioxide (CO2) capture is considered as an efficient method to reduce CO2 emission, ionic liquids with outstanding properties have be proposed as better CO2 capture agents. However, for ionic liquids with two CO2 reactive sites, the inhibition is a common problem which makes low capacity because one of the site less active or inactive. This situation inspires us to study the inhibitory mechanism of CO2 capture by ionic liquids with two sites. In this project, we plan to synthesize anion-bifunctionalized ionic liquids as CO2 absorbents and study the inhibitory mechanism through tunning the activity of sites and the structure of cation, furthermore, strategies of designing dual-sites ionic liquids with cooperative effect for efficient CO2 capture would be developed. Firstly, the proposed competitive inhibition between two active sites would be investigated through tunning the activity of one site. The active CO2 capture sites and capture pathway would be obtained through a combination of absorption experiment, spectroscopic investigation, and quantum chemical calculation, the effect of the relative basicity of the two sites on their CO2 capture activities would be analyzed subsequently. Secondly, the relationship between the structure of cation and the activity of two sites at anion would be studied, specially, the effect of the interaction between cation and anion on CO2 capture properties would be investigated. And then, bifunctionalized ILs with cooperative effect as efficient CO2 absorbents would be designed.

碳捕集是减少二氧化碳(CO2)排放的有效方法之一，离子液体的独特性质为CO2捕集剂的发展提供了机遇，然而在离子液体双位点功能化时，却普遍存在由于位点性能被抑制而造成容量低等问题。因此，本项目拟设计合成一系列阴离子双位点功能化的离子液体体系应用于CO2捕集中，研究该类体系碳捕集位点活性被抑制的机理，为协同作用提供设计策略。首先，通过调控阴离子中双位点的相对活性，结合碳捕集实验、谱学方法和量子化学计算，分析位点间相互竞争引起体系碳捕集方式和路径的差异，阐明双位点间相互影响引起位点抑制或协同的机理；其次，通过改变阳离子结构，分析双位点活性与阴阳离子间相互作用能的关系，揭示阳离子对阴离子双位点碳捕集性能的调控规律；最后，设计双位点协同作用的离子液体体系，实现高效碳捕集。

碳捕集是减少二氧化碳(CO2)排放的有效方法之一，离子液体(ILs)的独特性质为CO2捕集剂的发展提供了机遇。然而，在ILs双位点功能化时，却普遍存在由于位点性能被抑制而造成容量低等问题。因此，申请人等设计合成了氨基修饰的双位点碱性离子液体[P66614]2[R-AA] 研究双位点活性对碳捕集的协同与抑制作用的影响，并以[2-Op]阴离子为探针研究了ILs中阳离子调控阴离子双位点性能规律。通过IR\NMR\DSC\TGA等手段表征这类ILs的结构和物性，考察这类ILs捕集CO2的性能，结合量化计算和谱学分析研究了这类ILs捕集CO2的机理，揭示ILs中双位点捕集CO2中存在性能抑制是因为位点的碱性过强所致，当双位点的碱性相当时，双位点协同作用达到最高的CO2 捕集性能；阳离子通过与阴离子静电作用和氢键作用引起的电荷富集而抑制双位点捕集CO2的性能。基于此，申请人等合成了一批通过协同作用高效碳捕集的双位点功能化ILs：合成的[Ph-C8eim][2-Op]在20 oC、1 Bar CO2压力下，容量可以达到1.69 mol CO2/mol IL；合成的氨基修饰的双位点功能化离子液体[P66614]2[Am-iPA]在30 oC、1 Bar CO2压力下，容量可以达到2.38 mol CO2/mol IL。其次，申请人等从本项目中ILs的阴阳离子间氢键相互作用和双位点协同作用的思路得到启发，设计了一批通过多重氢键作用构建的可逆组装氢键网络框架用于NH3的高容量、高可逆性捕集；并等将双位点的协同作用应用到氨气捕集领域，合成了一批多位点协同作用捕集氨气的聚离子液体，能够达到优异的捕集容量，如Ph2Im-TBB-TA在25 oC和1 bar NH3压力下的氨气捕集容量为20.1 mmol NH3/g。通过本项目的研究，揭示了利用多位点的协同作用是高效捕集气体的有效手段，为气体捕集剂的设计提供可行的思路。