胺嫁接金属有机骨架复合结构对烟气中CO2吸附分离应用与机理研究

The technologies of CO2 capture and separation from industrial flue gas are of great significance for the mitigation of greenhouse effect. The proposed project will carry out the investigation on application and mechanism of organic amine-grafted metal-organic framework (MOF) composites for CO2 adsorption and separation from flue gas. The electronic properties of pore surface will be changed by grafting polyamine molecules (pyrazine, three triazine and urotropin etc.) onto the open metal sites in MOFs. As a result, the other uncoordinated and electron rich nitrogen atoms in polyamines act as active sites for CO2 adsorption. Thus, new separation mechanism of MOF material for CO2 adsorption in flue gas could be realized. Grafting of polyamines can change pore structures and surface chemical environment of MOFs to improve their gas separation performance. Moreover, through the introduction of electronic donor into MOF, the competitive adsorption of water molecules could be inhibited in a certain extent, thus reducing the damages of MOF frameworks resulting from water, and improving their life cycle. In this proposed project, performance testing and theoretical simulation will be combined to reveal the mechanism of CO2 adsorption and separation by organic amine-grafted MOF composites, supplemented by in situ Raman spectroscopy and in situ high resolution X-ray diffraction techniques. The study will give new ideas for CO2 adsorption and separation by means of functional porous materials, and provide theoretical support and experimental evidence for the development of novel adsorbent for decarbonization of flue gas.

工业烟气中CO2捕获与分离技术对缓解温室效应具有重要意义。本申请拟开展有机胺嫁接金属有机骨架（MOF）复合结构对烟气中CO2吸附分离应用与机理研究。通过在系列MOF材料的开放金属点上配位嫁接多胺（吡嗪、三嗪及N杂化金刚烷胺等）分子，改变其孔道表面赋存电子特性，利用多胺中未参与配位的其它富电子氮原子作为CO2吸附活性位，从而实现MOF材料对烟气中CO2吸附分离机制的转换。嫁接的多胺不但可改变MOF的孔道结构和表面化学环境，提高其气体分离性能；还可在某种程度上通过引入的电子给予体抑制水分子的竞争吸附，减少对MOF骨架的破坏，提高其循环使用寿命。该项目将通过性能测试和理论模拟相结合，辅以原位拉曼光谱和原位高分辨X-射线衍射技术，揭示有机胺嫁接MOF复合结构的CO2吸附分离作用机理。该研究提出了利用功能性多孔材料吸附分离CO2的新思路，将为新型烟气脱碳吸附剂的开发设计提供理论支持和实验依据。

CO2的高效捕集可以有效降低CO2排放量，是后续实现碳源回收利用的重要前提，对实现我国碳达峰和碳中和的战略目标具有重要意义。本项目立足于开发高效吸附分离工业烟气中CO2的多孔吸附剂材料，通过在金属有机骨架母体结构中嫁接复合有机胺实现了吸附机制的转变和多重吸附效应的耦合，从而提高了材料的CO2吸附与分离性能。项目组探索了多种有机胺嫁接金属有机骨架复合结构的制备方法，提出溶剂“挤压”法的合成后有机胺修饰法新策略和混合氨基配体的合成前修饰法实现了复合材料制备方法上的优化，并确定了制备过程中合成方法、有机胺含量、混合配体比例等影响复合材料结构稳定性的最优化合成条件。同时，我们还研究了母体MOF的骨架结构、开放金属位点，以及有机胺的结构、种类、含量对有机胺嫁接MOF复合材料的CO2吸附分离性能的影响，分析了材料结构与吸附分离性能之间的构效关系，通过优化组合得到了多种具有高效CO2吸附与分离性能的有机胺嫁接MOF复合材料。我们在实验数据的基础上进一步通过理论计算，推测出了复合材料的结构以及和CO2之间的相互作用位点，提出了合理的CO2吸附分离机理。本项目工作为今后设计制备高稳定性和高CO2吸附分离性能的复合吸附剂材料提供了实验和理论依据，对助力实现我国化石能源的低碳化发展、集约化利用具有现实意义。