反负载型纳米多孔金/金属氧化物催化剂的制备及其CO催化氧化性能研究

The exploration of nanosized gold catalysts have been an intense research spot in the development of new materials due to their important applications in heterogeneous catalysis in terms of unique low-temperature catalytic activity and high moisture-tolerance. Current work is aimed at the design and exploration of novel inversely-supported gold catalysts with metal oxides supported on nanoporous gold surface with the interests on the physical origination of high catalytic activity over nanoporous gold catalysts. Upon selectively dealloying of a series of Au-based binary alloy precursors, three dimensional bicontinuous inversely-supported gold/metal oxides composites can be achieved controllable preparation by in detail exploring the effect of electrolyte property, corrosion time, temperature, and applied potential on the evolution of structure dimensions, the residual components and chemical state of the residual metals. Based on the as-made gold catalysts, we will systematically investigate their catalytic activityies towards CO oxidation and the corresponding microscopic reaction kinetics. It is interesting to study the influence of different metal oxide species, ligament size, the surface components of residued metal oxides, and the moisture in reaction gas on the catalytic performance of the as-made catalysts, followed by optimizing the most reactive catalyst system. By combining the experimental observations with the theoretical calculations, we will explore the role of metal oxides during catalytic process and the possible physical origination for gold catalysis. The related investigations are beneficial for providing new physical understandings for the gold heterogeneous catalysis as well as promoting the development and application of novel nanosized gold catalysts.

纳米金催化剂因其优异的低温催化活性与抗潮湿能力成为新材料开发与催化应用领域的研究热点。本项目以纳米多孔金高催化活性的起因研究为指引，拟采用去合金化方法腐蚀一系列金基二元合金前驱体，通过调控去合金化条件，制备出新颖的反负载型纳米多孔金/金属氧化物催化剂。主要研究电解液的性质与浓度、腐蚀时间、温度、腐蚀电压等因素对产物结构尺寸、残留金属的化学状态及含量的影响，实现对三维空间内相互连续的反负载型纳米多孔金/金属氧化物的可控制备。研究所制备催化剂的CO催化氧化性能与微观反应动力学，系统探讨孔壁尺寸、不同残留金属氧化物及其表面含量、反应气体中水汽含量对催化性能的影响，筛选出性能优越的催化剂体系，结合理论计算分析残留金属氧化物在多孔金催化中的角色及多孔金高催化活性可能的起因。此项工作的开展将丰富多相催化领域的基础科学研究，促进新型金催化剂材料的开发与应用。

金催化剂的开发一直是催化应用领域的研究热点。本项目制备了AuCu，AuAl，AuMn，AuMg四种二元合金，主要采用电化学去合金化方法选择性腐蚀其中的活泼元素，腐蚀过程中残留金属自发的结合环境中的氧形成相应的金属氧化物，制得不同性质残留金属氧化物的反负载型纳米多孔金。通过探讨电解液、腐蚀电压、电解液浓度等因素对纳米多孔金结构的影响，成功制备了不同孔壁尺寸和不同氧化物残留量的纳米多孔金催化剂。通过探讨惰性Al2O3与活性CuO残留的两种多孔金的CO催化氧化活性，这两种金催化剂表现了相似的CO反应速率、转换频率、表观活化能以及相似的反应级数。研究还发现表面残留Mn3O4的多孔金催化剂，随着孔壁尺寸增加多孔金的CO催化氧化活性降低，表明表面残留的Mn3O4与多孔金的界面没有起到主要的催化作用，活性的降低是由于随着尺寸增加表面低配位金原子数量减少导致的。本研究证明在反负载型纳米孔金催化剂体系中，少量的不同氧化物残留对金的催化活性几乎没有影响，起催化本质的是金本身。本研究工作的开展对金催化活性起因的探索和确认具有重要的意义，为金催化剂活性的起因提供了新的理解与认识，丰富了多相催化领域的基础科学研究。