高分散-高稳定的嵌入式介孔Au@TiO2催化剂的可控合成及性能研究

In recent years, gold-based catalysts have attracted widespread interest due to their excellent catalytic performance in the heterogeneous catalytic reactions. However, as a result of their low thermal stability, the gold nanoparticles (NPs) are prone to agglomeration during thermal treatment and reaction process, directly leading to the decrease of catalytic performance. Therefore, the preparation of gold-based catalysts with high dispersion and thermal stability has become an attractive topic at home and abroad. By template of mesporous SBA-15 with controllable pore size distribution, this project will use many synthesis methods to fabricate the mesoporous Au@TiO2 catalysts with embedded structure. Firstly, the gold NPs will be oriented decorated and highly dispersed through two-times grafting and coordination effects, and the embedded structure will be achieved to confine these NPs by the nanocasting method. Then, the original size and morphology of the gold NPs will be preserved by photochemical route. Finally, through calcination and etching, the hierarchical pore structure of catalysts will be produced to accelerate the mass transfer process during the reaction. After successful synthesis, the dispersion of these gold NPs and their interactions with carriers will be demonstrated by several modern characterization methods. Furthermore, the advantages of this embedded structure in terms of stabilizing the gold NPs and elevating the catalytic performance will be tested by probe of reactions such as the hydrogenation of CO2 to methanol. This project has potential value of theoretical study and practical application by contributing to innovative design of the nano-metal catalysts as well as development of key technologies for the immobilization of nanometallic particles.

纳米金催化剂在多相催化反应中表现出优异的催化性能而被广泛关注，但其研究瓶颈在于纳米金颗粒在高温处理及反应过程中易团聚成大颗粒导致活性降低，因此，制备高分散、高稳定的纳米金催化剂成为国内外研究的热点。本项目拟以孔径可控的介孔SBA-15为模板，结合多种合成手段制备嵌入式介孔Au@TiO2催化剂：其中，二次嫁接和配位过程保证金物种的定向分布和高度分散；纳米浇筑形成嵌入式结构包裹纳米金；光反应还原维持纳米金颗粒原有的尺寸及形貌；焙烧和碱刻蚀形成多级孔道结构，加速反应传质过程。在此基础上，利用多种测试手段对纳米金颗粒的分布及其与载体间的相互作用进行表征，并以CO2加氢合成甲醇等反应为探针，与传统催化剂进行对比，明确嵌入式结构对稳定纳米金颗粒、提高催化剂性能的作用优势。本项目的实施有助于创新金属催化剂的设计、制备思路，发展高温条件下稳定纳米金属颗粒的关键技术，具有良好的理论研究和实际应用价值。

纳米金催化剂在多相催化反应中表现出优异的催化性能而被广泛关注，但其研究瓶颈在于纳米金颗粒在高温处理及反应过程中易团聚成大颗粒导致活性降低。本项目以介孔SBA-15为模板，结合多种合成手段制备嵌入式介孔Au@Co3O4催化剂：其中，二次嫁接和配位过程保证金物种的定向分布和高度分散；纳米浇筑形成嵌入式结构包裹纳米金；原位还原维持纳米金颗粒尺寸及形貌；焙烧和碱刻蚀形成多级孔道结构，加速反应传质过程。在此基础上，将活性位调控的方法推广到其他过渡金属催化剂中，通过引入不同过渡金属，包括单组分、多组分，将活性位固载在介孔分子筛不同位置上，并利用多种测试手段对活性金属的分布及其与载体间的相互作用进行表征，明确活性位调控对稳定纳米金属颗粒、提高催化剂性能的作用优势。本项目的实施有助于创新金属催化剂的设计、制备思路，发展高温条件下稳定纳米金属颗粒的关键技术，具有良好的理论研究和实际应用价值。.主要成果有：.1、利用二次嫁接、纳米浇筑、原位还原及表层刻蚀等技术，成功制备嵌入式介孔Au@Co3O4催化剂，实现纳米金颗粒的高度分散，金颗粒平均粒径大小为1.9nm，并且将纳米金催化剂的热稳定性从传统催化剂的350oC提高到500oC。.2、将纳米金催化剂的制备方式扩展到其他过渡金属催化剂，通过调控不同过渡金属在介孔分子筛材料的骨架、孔道、孔壁等不同分布位置上，研究不同位置上过渡金属与介孔分子筛载体之间的相互作用，并考察其催化反应活性及稳定性。.3、制备具有光响应性能的g-C3N4、MOFs等光催化复合材料，通过调控不同材料之间的相互作用，考察光催化性能提高机制，并研究催化反应机理。