完全分散非常规晶态金属催化界面的调控构建与表征

Enhancements in both dispersion and intrinsic activity are key factors for obtaining efficient metal catalysts, but it is difficult to achieve simultaneously in both aspects for state-of-art nano-metal catalysts. In view of the situation, this program plans to obtain the manipulative methods for preparing the catalysis interface of active metal component with both high dispersion and remarkable intrinsic activity by modulating construction of the fully dispersed active metal interface in unconventional crystalline state such as high-index crystalline on the surface of substrate-metal nanoparticles or oxide supporters, and investigate the catalytic performance of prepared samples through proper heterogeneous catalysis reactions for discovering or innovating some novel and efficient catalysis systems based on the metal catalysis interface designed in the program. On such metal catalysis interfaces, it could be available for tightly concentrating the characterizations of physical chemistry features of metal catalysts on the components in metal catalysis interface those really played the role in reactions, which would be benefit for recognizing the “structure-performance” relation or the essence with high-precise in metal catalysis; in combination with the obtainable “synthesis-structure-performance” regulations during preparations and characterizations of samples, it would provide references in designing morphology and modulating property of metal catalysis interface from microscopic views, which would help to expand the methods for designing or synthesizing novel metal catalysis materials and give light on innovating metal catalysts with high performances.

提高金属分散度和提高金属催化界面的本征活性是获取高性能金属催化剂的两个关键因素，而目前广泛使用的纳米金属催化剂，二者通常不可兼得。针对这一情况，本项目拟以纳米金属和氧化物为基底，在它们表面调控构建达到或接近完全分散的高指数晶面等非常规晶态活性金属催化界面，选择合适的多相催化反应表征其催化性能，期望由此获得将活性金属制备为兼具高催化利用率和高本征活性催化界面的控制方法，发现或创立一些基于此类金属催化界面的高效催化新体系。在此类样品上，可望实现将对金属催化剂物理化学性质的表征紧密聚焦于真正能参与化学反应的金属催化界面，由此更精准认识金属催化的“构-效”规律和作用本质；结合制备、表征此类材料过程中所得到的“合成-结构-性能”规律，为从微观角度设计、调控金属催化界面的形态和性质提供参考，由此拓展金属催化新材料的设计合成思路，为创制新型高性能金属催化剂提供依据。

以构建完全分散非常规晶态金属催化界面为核心，调控合成了4系列代表样品，着重分析样品表界面结构特征及这些特征对反应动力学因素或过程及反应性能的影响，明确了相关“合成-结构-性能”联系和变化规律。具体为：1.通过氧化还原蚀刻调控构建了金属基或金属氧化物基完全分散非常规晶态复合催化界面，在实现活性组分高催化利用率同时，通过组分与基体的紧密高分散结合，可形成异于常规样品的表面原子排布（金属高指数晶面或复合氧化层非晶态复合表面）、界面层特殊离子分布或氧化键合状态，促进反应物种的活化过程或界面电荷转移过程，提升了NH3-SCR-NO、光催化降解染料等反应性能；2.开发静电耦合锚定-原位氧化还原固化体系，实现了以有机聚合物或常见金属氧化物为载体，获取负载型高分散金属或金属氧化物催化剂，可在一定的金属宽载量（从0.2wt.%提高20倍）范围内, 将金属（如Pd）维持为尺度≤ 5.0 nm的高分散纳米颗粒，由此稳定高效催化加氢反应；3.以原位生长二维纳米片前体方式实现了直接在载体上构建小尺度活泼金属（Ni，ca. 2.8 nm）催化剂，所得高分散催化剂表面洁净、与载体结合力较强而结构稳定，对芳环加氢反应活化能显著降低，本征活性（TOF）呈数量级提高；4.尝试了以MOFS前驱法或水热杂合体系合成了金属-金属氮化物、稀土磷酸盐-金属磷化物等新型复合界面材料，明确了这些界面对反应底物特殊的吸附活化作用或反应途经选择性，发现了它们在不饱和醛酮选择性加氢、生物质平台分子转化等高价值反应中的应用潜力。综上，由项目开展获得了一些将活性金属制备为兼具高催化利用率和高本征活性催化界面的控制方法，以此为基础发现了一些高效催化新体系，并拓展了就相关固态多组分催化界面组成、结构对反应微观过程、宏观性能影响规律的认识，由此为设计、调控获取更高效多相催化体系提供了新参考，达成计划目标。