Collaborative Research: Integrated Measurement and Predictive Modeling of Adsorbate Coverage and Compositional Effects on Catalytic Activity

非均相固体催化剂被广泛用于促进所需的化学反应。 一个非常常见的例子是汽车催化转化器，它催化发动机废气中对环境有害的成分转化为良性产品。 什么？活跃？催化转化器中的催化剂含有昂贵的贵金属如铂、钯和铑作为活性金属位点。 其他对社会至关重要的过程，如生产化肥用氨或燃料用汽油，都依赖于催化剂来促进关键的化学反应。 在这些情况中的许多情况下，可用的催化剂是昂贵的，性能不太理想，或者随着时间的推移性能严重下降。 此外，有许多反应的良好催化剂是完全未知的。在大多数情况下，非均相催化反应发生在催化剂表面。这种界面传统上是在超高真空下研究的，在那里比较容易梳理出各种化学事件。 量子力学，密度泛函理论（DFT），分子模型非常适合于研究这些界面和过程中的高真空极限。 然而，在这些传统方法和具有催化作用的真实的条件之间仍然存在差距。 现在很好地理解，在操作条件下，催化剂表面通常挤满了许多分子，并且这些分子甚至可以导致催化剂表面改变形状或化学形式。 为了理解和改进多相催化剂，必须在这些更现实的条件下研究和模拟它们。 美国国家科学基金会催化生物催化计划正在授予三位研究人员，圣母大学的William Schneider和富兰克林陶教授以及西北大学的Christopher沃尔弗顿，通过先进的计算机模型和环境压力实验的结合，合作解决高压挑战。 通过结合施耐德在巴黎圣母院的催化反应的分子水平建模的专业知识和沃尔弗顿在西北大学的多尺度簇扩展模型的专业知识，将开发工具来预测反应条件下金属表面的行为。 这些工具将根据陶在圣母院的环境压力实验进行开发和验证。 工作人员将特别研究CO和NO在铂和铑表面的反应，这些反应与环境保护有关。 学生将接触到一个跨学科，多机构的合作研究计划，这将导致思想的交叉施肥。三名研究生将在主要研究人员的指导下共同研究理论和实验。 这些模型将传播到催化剂界，并有可能促进现有催化剂的应用和发现新催化剂的设计原则。

ABSTRACTHeterogeneous, solid catalysts are widely used to promote desirable chemical reactions. One very common example is the automotive catalytic converter, which catalyzes the chemical conversion of the environmentally hazardous components of engine exhaust into benign products. The ?active? catalysts in the catalytic converter contain expensive precious metals, like platinum, palladium, and rhodium as the active metal sites. Other processes critical to society, like the production of ammonia for fertilizer or of gasoline for fuel, all depend on catalysts to promote the key chemical reactions. In many of these cases the available catalysts are expensive, perform less than perfectly, or seriously degrade in performance over time. Further, there are many reactions for which good catalysts are simply unknown. In most cases, heterogeneous catalytic reactions happen at the surface of the catalyst. This interface has traditionally been studied under ultra-high vacuum, where it is relatively easy to tease out the various chemical events. Quantum mechanical, density functional theory (DFT), molecular models are well suited to studying these interfaces and processes in the high vacuum limit. There remains however a gap between these traditional approaches and the real conditions of catalytic interest. It is now well understood that at operating conditions, a catalyst surface is often crowded with lots of molecules and that these molecules can even cause the catalyst surface to change shape or chemical form. To understand and improve heterogeneous catalysts, one must study and model them at these more realistic conditions. The National Science Foundation Catalysis & Biocatalysis Program is awarding three researchers, Professors William Schneider and Franklin Tao of Notre Dame University and Christopher Wolverton of Northwestern University to collaboratively tackle the high-pressure challenge through a combination of advanced computer models and ambient pressure experiments. By combining the expertise of Schneider at Notre Dame in molecular-level modeling of catalytic reactions with the expertise of Wolverton at Northwestern in multi-scale cluster expansion models, tools will be developed to predict the behavior of a metal surface under reaction conditions. The tools will be developed and validated initially against the ambient pressure experiments of Tao at Notre Dame. The workers will study in particular the reactions of CO and NO at platinum and rhodium surfaces, reactions relevant to environmental protection. The students will be exposed to an interdisciplinary, multi-institutional collaborative research program which will lead to cross-fertilization of ideas. Three graduate students advised by the principle investigators will work together on the theory and experiments. The models will be disseminated to the catalyst community, and have the potential to advance both the application of existing catalysts and discovery of design principles for new ones.