石墨烯担载Au-Pd双金属催化剂的可控合成及其甲醇选择氧化性能研究

Selective oxidation of methanol is one of the most important routes to produce methyl formate, due to its mild reaction conditions and environmental benignity. Among the various catalysts used, Au-M (Pd, Ag, etc.) bimetallic catalysts exhibit superior activity and selectivity in methanol oxidation. Until present, however, the effect of Au-M morphology on catalytic activity, Au-M synergism and the related reaction mechanism have not been well understood. In this project, therefore, the graphene is used as the carrier of Au-Pd bimetallic catalysts for the selective oxidation of methanol, to benefit from its large surface area and high thermal and electrical conductivity. Through altering the preparation method and optimizing the preparation conditions, the morphology and structures of Au-Pd active sites can be precisely controlled and the relationship between catalyst structure and catalytic activity can be clarified; by using different graphenes, the intrinsic connections between the function of graphene, Au-Pd synergism and catalytic activity in methanol oxidation can be explored; via reaction kinetics study and in-situ characterizations, the reaction mechanism can then be proposed. The progresses made by performing this project will promote the researches on catalytic applications of graphenes and be of benefits to further understanding of structure-performance relations, Au-Pd synergism and reaction mechanism for methanol oxidation. It may also provide us some new thoughts to the design and preparation of efficient bimetallic catalysts in nano-scale.

甲醇选择氧化法是一种制备甲酸甲酯的重要方法，具有反应条件温和、环境友好等优点。在众多甲醇选择氧化催化剂中，Au-M（Pd、Ag等）双金属催化剂具有较为优异的活性和选择性。然而，人们在此类催化剂涉及的构效关系、协同作用机制和反应机理等方面尚缺乏清楚的认识。本项目拟采用高比表面和强导电能力的石墨烯为载体担载Au-Pd双金属催化剂用于甲醇选择氧化，通过改变制备方法和优化制备条件精确控制Au、Pd纳米粒子尺寸、形貌以及结构，深入研究Au-Pd形貌、结构与催化活性之间的有机联系；采用不同特性的石墨烯，探究石墨烯载体效应、Au-Pd协同作用及甲醇选择氧化性能之间的内在关系；通过催化反应动力学和原位表征等研究提出反应机理。本项目取得的进展将促进以石墨烯为基质的催化应用研究，加深对Au-Pd构效关系、协同作用和甲醇选择氧化反应机理等方面的科学认识，为从纳米尺度上设计制备新型高效双金属催化剂提供新思路。

甲醇选择氧化制备甲酸甲酯是甲醇下游化的重要反应之一，Au-Pd双金属催化剂用于甲醇选择氧化具有反应条件温和、环境友好和活性高等优点。然而，人们在此类催化剂涉及的构效关系、协同作用机制和反应机理等方面尚缺乏清楚的认识。通过本项目的实施实现了石墨烯上金属颗粒形貌和尺寸的可控制备，阐明了AuPd双金属协同作用机制、石墨烯载体效应以及甲醇选择氧化反应机理。具体内容如下：（1）实现了石墨烯担载Au-Pd双金属催化剂的形貌、结构及颗粒大小的可控合成，合成了具有结构均一、高度分散的均匀合金结构，核壳结构及亚纳米团簇结构的AuPd金属颗粒；（2）研究了Au、Pd的形貌和结构对甲醇选择氧化催化性能的影响，确定了甲醇选择活性与金属颗粒大小和合金结构具有重要关系，结果表明均匀合金结构活性>核壳型合金结构>同尺寸单一金属颗粒；（3）研究了石墨烯载体效应，发现石墨烯通过与AuPd之间形成s-p-d轨道杂化，促进了AuPd之间的电子交换和迁移，增强了双金属催化剂的协同作用，从而促进了甲醇选择氧化活性的提高。本项目取得的进展加深了对Au-Pd构效关系、协同作用和甲醇选择氧化反应机理等方面的科学认识，促进了以石墨烯为基质的催化应用研究，为从纳米尺度上设计制备新型高效双金属催化剂开辟了新思路。