酰胺/草酰胺基团修饰的MOFs的合成及其CO2吸附和催化转化研究

CO2 as a chief greenhouse gas, its adsorption and conversion utilisation have a far-reaching meaning. The formation of cyclic carbonates through the reaction of CO2 with epoxides is one of main approaches for CO2 utilization, and in which metal-organic frameworks (MOFs) because of unique structures are the newly appearing catalysts with a broad application prospect. On the basis of careful analyses for the research of existing MOFs applied in the adsorption and catalytical conversion of CO2, this item, considering functional application-oriented and structural stability, proposes the functionality of organic ligands to synthesize MOFs by using the designed two types of azolate and azolate-carboxylate ligands containing acylamide/oxalamide groups. In these ligands, the acylamide/oxalamide groups would be the strong adsorption sites of CO2, while the azolate groups could enhance stability of MOFs. Furthermore, the structures of MOFs and their pores will be systematically tuned by altering different factors, such as types and connecting directions of azolates in ligands, ligand shapes and so on. Then, by the combination of theoretical simulations and experimental results, we will explore focusedly the relation between structures and performances of CO2 adsorption and catalytic conversion of MOFs, and also clarify the mechanisms of adsorption and catalysis. Through this investigation, we will not only obtain several stable MOF materials possessing significant CO2 uptake and selectivity as well as efficient catalytic conversion for CO2 but also provide an important theory evidence for the design and exploitation of MOF catalysts.

CO2作为主要的温室气体，它的吸附和转化利用具有深远的意义。与环氧化物反应生成环状碳酸酯是利用CO2的重要途径之一，MOFs材料由于独特的结构使其成为该类反应新兴起的具有广阔应用前景的催化剂。本项目在分析现有MOFs对CO2吸附和催化转化研究进展的基础上，以功能应用为导向，以结构稳定性为前提，从有机配体的功能化着手，提出利用含有酰胺/草酰胺基团的氮唑和氮唑-羧酸两类配体合成MOFs，其中酰胺/草酰胺基团是强CO2吸附位点，氮唑则能提高MOFs的稳定性；进而利用配体中氮唑的种类和连接方向以及配体形状等因素对MOFs的结构和孔结构进行系统地调控；然后结合理论模拟和实验结果，重点探索MOFs的结构与其对CO2吸附和催化转化性能之间的构-效关系，阐明吸附和催化机理；获得结构稳定，对CO2吸附量大、选择性高且催化转化性能好的MOFs材料，为相关催化剂材料的设计和探索开发提供重要依据。

CO2捕获和转化利用，是助力“双碳”目标实现的重要途径之一，开发具有相关功能的新材料具有重要意义。基于此，本项目依据金属-有机框架（MOFs）材料结构上和功能上的优点，设计合成了含有酰胺、草酰胺等不同基团的有机配体，并与不同的金属离子反应，组装了近50例MOFs新材料，深入揭示了构-效关系。主要研究内容包括：1）系统地考察了配体构型、配位模式、溶剂和金属离子类别等因素对MOFs结构的影响，为MOFs的定向组装提供了重要的指导方法；2）在反应体系中引入氮杂环配位基元，成功地制备了一系列具有热稳定性和化学稳定性的MOFs；3）引入有机取代基团成功地提高了MOFs对CO2气体的吸附选择性，实现了CO2与CH4、C2H2、C2H4等气体之间的高效分离；4）制备的MOFs在无溶剂的常规安全反应条件下实现了CO2与不同环氧烷烃的高效催化转化（转化率达到95%以上），生成具有重要应用价值的环状碳酸酯化工产品，表现出潜在的应用前景。本项目研究成果为CO2捕获与转化功能导向MOFs材料的设计合成提供了重要的科学依据和理论指导。项目执行期间，负责人以通讯作者在Angew. Chem. Int. Ed., Chem. Sci., Appl. Catal. B: Environ., Chem. Eng. J., J. Mater. Chem. A, ACS Appl. Mater. Interfaces, Sep. Purif. Technol.等化学期刊发表SCI论文41篇，其中13篇论文的影响因子大于10，3篇论文入选了ESI 1%高被引用论文，授权发明专利5件，达到预期研究目标。