Collaborative Research: Experimental and theoretical study on the structure and catalytic activity of metal cluster/metal oxide interfaces

合作研究：金属簇合物/金属氧化物界面的结构和催化活性的实验和理论研究

• 批准号: 1032979
• 负责人: Adri van Duin
• 金额: $ 25.9万
• 依托单位: Pennsylvania State Univ University Park
• 依托单位国家: 美国
• 项目类别: Standard Grant
• 财政年份: 2010
• 资助国家: 美国
• 起止时间: 2010-09-01 至 2014-08-31
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=1032979&HistoricalAwards=false
• 关键词: Collaborative; Research; Experimental; theoretical; study

1032979van DuinThe most successful metal/metal oxide catalysts currently available involve highly-dispersed, low-concentration metal atoms embedded in a metal oxide surface. Palladium metal supported on cerium oxide, is an important example of a highly active catalyst, with applications as an automotive three-way catalyst, in catalytic combustion, and as a solid oxide fuel cell anode material. The activity of these metal/metal oxide catalysts can be uniquely controlled by the support surface structure. Furthermore, these low-concentration metal catalysts have demonstrated significant resistance against sintering, a common multi-component catalyst degradation mechanism, thus indicating superior resistance to heating/cooling cycles and changes in redox enviroment. However, the structure of the active site is challenging to define at the atomistic scale. For the metal-ceria (M/CeO2) catalytic system, dynamic restructuring occurs under reaction conditions and both the ceria and metal structure alter reactivity. So how then to explain the catalytic and performance behaviors of Pd on ceria? Three Investigators, A.C. van Duin and M. J. Janik of Pennsylvania State University and M. M. Batzill of the University of South Florida, hypothesize that mixed surface oxides of Ce1-xPdxO2-d may provide unique active sites with high activity and stability under certain reaction conditions. To confirm this and in order to fully develop the potential of Pd/CeOx and similar metal/metal oxide catalysts, they believe a detailed, atomistic-scale knowledge of the catalytic conversion mechanisms and the surface dynamics related to substrate-surface interactions is required for the Pd/ceria system. In a collaborative study, the PIs propose to utilize atomistic simulation with Reactive Force-Field (ReaxFF) and Density Functional Theory (DFT) approaches together with experimental surface science studies to investigate the dynamic structure and reactivity of Pd/CeO2 systems. The combined surface science and ReaxFF/DFT approach will provide detailed determination of the structure, stability, and activity of Ce1-xPdxO2-n mixed oxide surfaces. This will help answer questions about this catalyst system.From the broader perspective, the combination of experimental and computational approaches applied to this complex catalytic system will advance the fundamental understanding of the effect of reducible oxide supports on catalyst stability and activity, as well as provide guidance towards the preparation of highly active M/CeO2 catalysts. Further, the development of an integrated, two-component simulation environment, which is validated against experiment is the outcome of this project. This collaboration between simulation and experiment will provide a roadmap for future catalytic research; the computational tools developed here are generally applicable, thus providing straightforward extension to other catalytic materials.The research program also closely integrates education and outreach activities. Specifically, at PSU, courses for engineers on atomistic-scale simulation methods will be introduced, which will be complemented by lectures and tutorials on experimental techniques.

目前最成功的金属/金属氧化物催化剂涉及嵌入金属氧化物表面的高度分散、低浓度的金属原子。负载在氧化铈上的钯金属是高活性催化剂的重要实例，其应用为汽车三效催化剂、催化燃烧中以及作为固体氧化物燃料电池阳极材料。这些金属/金属氧化物催化剂的活性可以通过载体表面结构唯一地控制。此外，这些低浓度的金属催化剂已经显示出显著的抗烧结性，这是一种常见的多组分催化剂降解机制，因此表明对加热/冷却循环和氧化还原环境变化的上级抗性。然而，活性位点的结构在原子尺度上定义是具有挑战性的。对于金属-氧化铈（M/CeO 2）催化体系，在反应条件下发生动态重组，氧化铈和金属结构都改变反应性。那么，如何解释钯在二氧化铈上的催化和性能行为呢？三个调查员，A. C.货车Duin和M. J. Janik和M. M.南佛罗里达大学的Batzill假设Ce 1-xPdx O 2-d的混合表面氧化物可以提供在某些反应条件下具有高活性和稳定性的独特活性位点。为了证实这一点，并为了充分开发Pd/CeOx和类似金属/金属氧化物催化剂的潜力，他们认为Pd/二氧化铈系统需要详细的，原子级的催化转化机制和与基底表面相互作用相关的表面动力学知识。在一项合作研究中，PI建议利用原子模拟与反应力场（ReaxFF）和密度泛函理论（DFT）方法以及实验表面科学研究来研究Pd/CeO 2系统的动态结构和反应性。结合表面科学和ReaxFF/DFT方法将提供详细的测定Ce 1-xPdxO 2-n混合氧化物表面的结构，稳定性和活性。这将有助于回答有关这个催化剂系统的问题，从更广泛的角度来看，实验和计算方法相结合，适用于这个复杂的催化体系将推进可还原的氧化物载体对催化剂的稳定性和活性的影响的基本理解，以及对高活性的M/CeO 2催化剂的制备提供指导。此外，一个集成的，两个组件的仿真环境，这是对实验验证的发展是这个项目的成果。模拟和实验之间的这种合作将为未来的催化研究提供路线图;这里开发的计算工具是普遍适用的，从而提供了直接的扩展到其他催化材料。具体而言，在PSU，将引入原子级模拟方法的工程师课程，并将通过实验技术的讲座和教程进行补充。