有序大孔-介孔-微孔多级孔分子筛催化剂的设计合成及应用

Zeolites, possessing crystalline frameworks and ordered networks of micropores (typically 0.25-1.5 nm), have been widely used as important heterogeneous catalysts in a number of industrial processes, such as oil refining, petrochemistry and organic synthesis. However, with an increasing need for faster diffusion rates of reactants and higher conversion rates of bulky molecules, it is universally acknowledged that the intracrystalline diffusion limitations, stemming from the relatively smaller micropores, limit the performance of industrial zeolitic catalysts. Recently, the concept of introducing supplementary pores (meso-/macropores) into zeolite materials to fabricate hierarchically structured zeolites has gained increasing interest due to the combination of the advantages of both multimodal porous systems and zeolite crystals. Although many hierarchically structured zeolites have been successfully developed, achieving an ideal hierarchically macro-meso-micro porous structure within zeolite materials is a great challenge, especially for the ordered hierarchically macro-meso-microporous structure. To make full use of a hierarchical system during a catalytic reaction it is vital that the connectivity between the various sizes of pores is maximized. This project focuses on 1) design and synthesis of ordered hierarchically macro-meso-micro porous zeolitic catalysts, 2) investigation and development of the synthesis mechanism that combines templating method with crystallization transformation process, 3) the influence of ordered macro-meso-micro porous hierarchy on diffusion property and the resultant catalytic performances. Ordered hierarchically macro-meso-micro porous structure can be achieved by the organized design of ordered hierarchically porous structure on the based of novel synthetic method. A series of hierarchically porous zeolites with interconnected porosity, high stability and superior catalytic performance can be obtained. The synthesis mechanism of hierarchcially ordered macro-meso- micro porous zeolite catalysts will be carefully investigated. Furthermore, the influence laws of ordered macro-meso-micro porous hierarchy on diffusion property and the resultant catalytic performances will be investigated.

微孔分子筛催化剂已经被广泛地应用于石油化工、精细化学及有机催化合成等领域。然而微孔分子筛的孔径太小限制了其被广泛应用。多级孔分子筛材料的研究为解决这一关键科学问题提供一个全新的思路。当前，分子筛体系内多级孔道结构的构筑及其性能研究已经引起极大的关注。但是具有三级孔道结构大孔-介孔-微孔的分子筛催化剂的合成仍然很难实现，尤其有序大孔-介孔-微孔多级结构的构筑。本项目研究1）分子筛体系中有序大孔-介孔-微孔结构的设计合成及调控；2）模板法及转晶过程有机结合合成机制；3）有序多级孔道结构、分子流通扩散性能及其催化性能三者之间相互影响机制。通过在分子筛体系中有序大孔-介孔-微孔多级孔道结构的构筑，解决微孔分子筛催化剂材料孔径限制和功能化问题，制备多级孔道相互贯通、结构稳定的高效分子筛催化剂材料，并以此为模型深入研究多级孔道结构在有机催化应用中的优势，构建多级孔道结构与催化剂性能之间的相互影响规律。

微孔分子筛催化剂广泛地应用于石油化工、精细化学及有机催化合成等领域。然而其微孔孔径过小限制了其被广泛应用。等级孔分子筛材料的研究为解决这一关键科学问题提供一个全新的思路。当前分子筛体系内等级孔道结构的构筑及其性能研究已经引起极大的关注。但是具有三级孔道结构大孔-介孔-微孔的分子筛催化剂的合成仍然很难实现，尤其有序大孔-介孔-微孔等级结构的构筑。本项目主要研究内容为分子筛体系中有序大孔-介孔-微孔结构的设计合成及调控、模板法及转晶过程有机结合合成机制和有序等级孔道结构及其催化性能之间相互影响机制。我们实现了1) 有序大孔-介孔-微孔等级孔分子筛催化剂的设计合成。成功制备了有序大孔-介孔-微孔等级孔分子筛催化剂，同时实现了分子筛骨架取代杂元素的多元化，即实现了铝、钛杂元素对分子筛中骨架硅的取代。2) 有序大孔-介孔-微孔等级孔分子筛催化剂的结构控制。通过对大孔模板和介孔模板的可控选择，实现大孔孔道和介孔孔道的可控调控。3) 有序大孔-介孔-微孔等级孔道结构形成机制的研究。转晶过程的控制是实现前躯体中有序大孔-介孔结构保持的关键，通过详细研究合成过程，总结有序大孔-介孔-微孔等级孔分子筛的形成机制。4) 有序等级孔道结构与分子筛催化性能之间的相互影响机制的构建。通过选择经典的有机催化反应及具有代表性的有机大分子催化反应，深入研究有序大孔-介孔-微孔等级孔分子筛的催化性能，重点研究其在大分子有机催化应用上的优势。结果表明，在同一分子筛体系中构筑完全开放的三维有序的大孔-介孔-微孔等级孔道结构，同时结合分子筛纳米晶的优势，使所制得的分子筛在涉及有机大分子的催化氧化反应中表现出优异的催化性能。