螯合模板剂导向介孔复合材料的可控制备与性能研究

The crystal lattice defects of pure mesoporous silica are so less that it can not be used directly as catalyst. Other mesoporous materials such as transition metal oxides and sulfides also have some problems, for instance, poor thermal stability and pore structure is easy to collapse. Therefore, based on the property of the variable valence of metal ions, it is the efficient way to improve the catalytic performance by efficiently and uniformly doping the metal ions into the channels of mesoporous silica, loading them onto the surface of mesoporous silica and complexing them into the mesoporous silica skeleton. This project intends to use EDTA and citric acid as chelating structure unit and introduce different structures and chain length of the hydrophobic segment in one of its groups. Multi-tooth coordination effect, stable parameters, solution properties and micellization behavior of the chelating template would be investigated in detail. The object precursor would be introduced into the channels of mesoporous directionally, and then it can be realized the synchronization of doping and synthesis for the mesoporous materials effectively. Changing the mainskeleton material, template and functional organic silica source, the metal ions could be controlled to insert into the the mesoporous silica skeleton and load on the surface of the the mesoporous silica. The effect of the object introduced quantity, the structure, composition and properties of mesoporous against to the concentration of template agent, pH value of solution, the type of help structure directing agent, seasoning time and calcination condition are going to explore. Furthermore, the properties such as catalyst of the obtained mesoporous composites will be detected. This project can provide theoretic evidence for the choose and synthesis of chelating agent, and it also gives us an new way which features orderly structure, good stability, efficient reactivity, small and well distribution of object metal (oxide), it plays a significant role in the production and application of the mesoporous composite materials.

纯介孔二氧化硅的晶格缺陷少，难以作为催化剂直接使用，而过渡金属氧化物和硫化物等介孔材料尚存在热稳定性较差、孔结构容易坍塌等问题。因而利用金属离子的可变价态，将其有效、均匀地导向引入到介孔材料孔道中、负载于介孔材料表面及复合到介孔主体骨架中是提高其催化等性能的有效途径。本项目以乙二胺四乙酸和柠檬酸等为螯合性结构单元，定量引入不同长度的疏水链，详细研究其多齿配位作用、稳定参数、溶液性质及胶束化行为；以其为模板导向金属前驱体至介孔孔道中，实现介孔复合材料的合成与掺杂同步；改变骨架原料、模板剂及功能性有机硅源，使金属离子复合到介孔主体骨架中和负载于介孔材料表面；探索模板剂浓度、pH值、助导向剂类型及煅烧条件等对配位能力、客体引入量、介孔结构与组成等的影响，提高复合材料的催化等性能。项目的完成可为介孔复合材料的可控制备提供理论依据，构建结构有序、稳定性好，客体纳米粒子分布均匀和高催化活性的新方法。

多孔材料在催化、储能、气体分离以及组织工程等领域展示了广泛的应用前景。根据IUPAC分类标准，孔结构可细分为微孔 (<2 nm)、介孔 (2-50 nm) 以及大孔 (>50 nm)，而不同的孔结构会有截然不同的性质。因此在本项目研究中，从介孔结构的可控合成出发，首先展示了两亲性表面活性剂在分子前驱体形成中的重要作用，从而证明了分子设计策略在介孔复合材料合成中的可行性。制得的介孔复合材料明显提高了光催化降解效率和优异的循环稳定性。针对介孔结构传质速率以及表面浸润性仍不甚理想的问题，本项目通过构建大孔-介孔复合结构和采用非螯合型表面活性剂，制得了金属离子掺杂的大孔-介孔复合材料，极大地改善了介孔的表面润湿性，提高了传质速率，从而使其表现出更为优异的光催化性能。可以在10分钟内对罗丹明B的降解效率达100%，而在半小时内对双酚A的降解效率达80%以上。此外，根据本项目中介孔材料研究的诸多启示，我们设计合成了多种不同孔结构的复合材料，主要包括多孔气体分离膜、有机/无机复合多孔材料及多孔复合支架材料，实现其在气体分离、电子储能领域中的应用。本项目研究探明了分子前驱体的形成机理，实现分子前驱体的可控形成，进而展示了介孔结构的可控合成，并以此为基础，设计合成了诸多不同孔结构的复合材料，极大地改善了其在催化、储能、气体分离以及组织工程等领域的应用。因此，本项目研究不仅为介孔材料的可控合成具有重要的理论指导意义，也为其他多孔材料的设计合成以及应用提供了重要依据。