基于双硅层空腔结构调控与聚合物网点固载的“类分子筛” 型纳米Au簇催化剂的构筑及反应性能研究

To construct the catalytic system with the zeolite-like effect, several novel strategies including the encapsulation of double silica hollow structue, polymer dot immobilization and in-situ reduction of Au nanoclusters, have been carried out in this project to prepare the novel micropore H-SiO2/Au nanoclusters/micropore H-SiO2 catalyst. In this way, the size sieving catalysis toward different sizes of molecular reactants, can be exerted to the maximum extent by controllable regulation of the outer silica pore structure and spatial size in the double silica hollow structure, as well as the selective exposure of the Au nanoclusters. The self-assembly of Au nanoclusters can be realized by the existed strong metal complexation interaction between the grafted polymer dots with high amino content and the metal ion. Additionally, the in-situ reduction of nano Au clusters can be conducted under the specific conditions of reduction and oxidation heat treatment. The combined effects of collaborative confinement of double shell hollow structure and the enrichment of reaction products in the internal hollow structure are advantageous for the immobilization and dispersion of Au nanoclusters, as well as the diffusion and mass transfer of reactants. This project can mainly in-depth study the inherent law among the catalytic reaction performance, the regulation of double silica hollow structure and the size distribution of Au nanocluster. Accordingly, the mechanism of the unique catalyst structure to improve the catalytic efficiency and to increase the thermal stability can be illustrated explicitly. The implementation of this project can contribute to the innovative design of the noble metal cluster catalyst, and also to develop new technology for size sieving catalysis, with potential economic and social benefits.

本项目围绕构筑具有“类分子筛”筛分性能的催化体系，采用双硅层空腔结构封装、聚合物网点固载及纳米金簇的原位-还原技术制备新型微孔H-SiO2/纳米Au簇/H-SiO2催化剂。通过构建具有可调外表面微孔与层间径向尺寸的双硅层空腔结构，选择性暴露纳米金簇，实现催化体系对不同分子大小反应物的“择形催化”性能。利用外空腔结构内聚合物氨基骨架对金属离子的强配位络合作用，原位固载金离子。通过特定条件下的还原及氧化热处理，原位-还原纳米金簇，并根据双硅层空腔结构的“协同限域”效应与内空腔的产物收集作用，固化、分散纳米金簇，强化反应物质的扩散和传质。深入研究催化剂反应性能与双硅层空腔结构调控、纳米金簇尺寸分布间的内在对应关系，明确催化剂的独特结构对提高催化反应效率、增强纳米金属簇热稳定性的作用机制。本项目的实施有助于创新纳米催化剂的设计思路，发展纳米择形催化反应新技术，具有潜在的经济和社会效益。

本项目从提高纳米贵金属粒子的热稳定性、抑制其在催化剂制备及使用过程中发生的团聚、烧结等现象出发，通过构建功能化磁性核层结构，以Fe2O3微粒为内核，构筑复合椭球双硅层载体，将纳米Au粒子固载在载体中，得到具有优良磁分离性能、分散性与热稳定性的双空腔纳米Au催化剂。随后，采用基于乙二胺贵金属前驱物网点固载及超细纳米贵金属的原位还原技术，制备具有高分散性、高热稳定性的新型纳米贵金属催化剂，实现超细纳米贵金属颗粒的原位负载与封装固化。同时，采用溶胶凝胶法在内核Fe2O3上生长硅层，成功构筑出双金属氧化物双硅层催化剂。利用碱性水热转化法将纳米微球转变为中空双硅层纳催化剂，该制备方法能充分利用纳米片的逐渐生长形成保护层，提高催化体系的整体稳定性，较好促进丙烷脱氢反应的进行。另外，通过一步水热无模板法构建出多金属氧化物双硅层结构的系列催化剂，该封装方法能够充分结合不同金属氧化物的特点及金属氧化物纳米金粒子间的协同作用，显著提升催化反应活性与稳定性。项目的实施促进了纳米金属催化剂的设计、制备新思路，发展了有利于提高金属纳米粒子/簇热稳定性、构建具有独特催化体系结构的新技术，为化学工业及环境保护等领域内的高效催化剂研发提供了新思路，具有潜在的经济和社会效益。.项目实施期间，课题组分别在Journal of Catalysis、Applied Catalysis B: Environmental、Advanced Science、Journal of Materials Chemistry A、Carbon等学术期刊上发表SCI收录论文27篇（均标明资助），关键核心技术申请国家发明专利5件，获授权发明专利1件，培养博士研究生6人（已毕业4人），硕士研究生17人（已毕业10人）。项目执行期间，先后资助12人次参加了国内外各类学术交流活动（含口头报告6人次）。