多级孔磷酸铝分子筛的孔结构和形貌调控及催化性能研究

For microporous zeolites, the small pore dimension and low mass transfer performance are the main two factors that limit their applications in those catalytic reactions involving bulky molecules.The invention of hierarchical molecular sieves with micro- and meso-porous structure can efficiently solve these limitations. We proposed here for preparation of hierarchical SAPO-5 and FeAlPO-5 molecular sieves with more available active centers and excellent mass transfer properties.The pore structures and morphologies of the two materials can be tuned by varying the types of eutectic mixture and precusors, the compositions of reaction system and crystallization conditions under atmospheric pressures.The formation mechanism of these materials will be revealed by studying the roles of calcination, microwave heating and organic species, thus providing theoretical basis for the design of other types of hierarchically structured materials.The catalytic tests using alkylation and hydroxylation as probe reactions are systematically studied over a series of SAPO-5 and FeAlPO-5 catalysts prepared by different methods. The morphologies, pore structure, the properties of active species and mass transfer performances of these catalysts are further characterized by several advanced technologies. Based on these results, the relations among synthesis, structure and morphologies and catalytic performances will be revealed. The implementation of the prosed project can provide basic experimental results and scientific evidence for further design, synthesis of high-performanced catalysts used for alkylation and hydroxylation reactions.

传统微孔沸石材料较小的微孔孔径和低的传质效率是限制其在涉及大分子催化反应中应用的最主要的两个因素，多级孔分子筛的出现则能够有效地解决上述问题。本项目旨在通过改变低共熔混合物和前驱物种类，以及反应体系组成和晶化条件，实现在常压条件下多级孔SAPO-5和FeAlPO-5分子筛的孔结构和形貌的调控，探索制备一类具有更多有效活性中心以及优良传质性能的催化材料。通过深入探讨微波加热、高温焙烧和有机物种在多级孔形成中的作用，揭示出多级孔的形成机理，为其它类型的多级孔分子筛的合成提供理论依据。以烷基化和羟化反应为探针，系统地比较不同方法合成的多级孔SAPO-5和FeAlPO-5分子筛在催化性能上的差异，进一步通过先进的表征手段研究这些催化材料的形貌、孔结构、活性中心的性质和传质性能，在此基础上揭示合成-孔结构和形貌-催化性能之间的关系，为设计合成高性能的催化材料提供基础数据和科学依据。

中文摘要：限制传统微孔沸石材料在大分子的催化应用中的主要障碍是其较小的孔径和低的传质效率，而同时含有微孔和介孔的多级孔分子筛则能够有效解决该问题。本项目重点研究了多级孔SAPO-5和FeAPO-5的多级孔道的形成机制、形貌和孔结构的调控方法以及其在烷基化和羟基化反应中的催化性能，主要取得了以下研究结果。.1）通过分析微波加热、高温焙烧和有机物种对介孔参数的影响，揭示了FeAPO-5分子筛中多级孔道的形成机制。.2）通过改变硅源、铝源、氟源、磷源、低共熔混合物组成和晶化时间，实现了SAPO-5分子筛的形貌调控。.3）通过调变过饱和度、氟源和低共熔混合物的类型，实现了SAPO-5分子筛的孔结构的调控。.4）分析了多级孔SAPO-5分子筛的结晶度、酸量、形貌和孔结构参数与其在苯与苄基醇的烷基化反应中的催化性能的关系，发现催化剂的衍射峰强度比I002/I100与其催化活性之间有很好的依赖关系。研究了三种不同方法制备的FeAPO-5分子筛催化剂在苯酚羟基化反应中的催化性能，揭示了催化剂的孔结构和活性物种的性质与催化性能的关系。预测那些具有稳定的铁物种并且铁物种能被反应物和产物接近的催化材料将会在苯酚的羟基化反应中展示出优异的催化性能。. 上述研究成果的获得为高性能的用于烷基化和羟基化反应的催化材料的设计合成指明了研究方向。