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

多相固体催化剂被广泛用于促进理想的化学反应。一个非常常见的例子是汽车催化转化器，它催化发动机尾气中对环境有害的成分化学转化为无害的产品。主动型？催化转化器中的催化剂含有贵金属，如铂、钯和铑作为活性金属中心。其他对社会至关重要的过程，如生产用于化肥的氨或用于燃料的汽油，都依赖于催化剂来促进关键的化学反应。在许多这样的情况下，可用的催化剂价格昂贵，性能不佳，或者随着时间的推移性能严重下降。此外，有许多反应的好催化剂根本不为人所知。在大多数情况下，多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)、分子模型非常适合在高真空极限下研究这些界面和过程。然而，这些传统的方法与实际的催化条件之间仍然存在差距。现在人们都知道，在操作条件下，催化剂表面经常挤满了大量的分子，这些分子甚至会导致催化剂表面的形状或化学形态发生变化。要了解和改进多相催化剂，必须在这些更现实的条件下对其进行研究和建模。美国国家科学基金会催化与生物催化项目授予三名研究人员，圣母大学的威廉·施奈德教授和富兰克林·陶教授，以及西北大学的克里斯托弗·沃尔弗顿教授，他们通过结合先进的计算机模型和环境压力实验，共同应对高压挑战。通过将巴黎圣母院的施耐德在催化反应的分子水平建模方面的专业知识与西北大学的沃尔弗顿在多尺度团簇扩展模型方面的专业知识相结合，将开发出预测金属表面在反应条件下的行为的工具。这些工具将首先根据陶氏在巴黎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一氧化碳和一氧化氮在铂和铑表面的反应，这是与环境保护有关的反应。学生将接触到一个跨学科、多机构合作的研究项目，这将导致思想的交叉培养。三名研究生将在原理研究人员的建议下共同进行理论和实验方面的工作。这些模型将被传播到催化剂社区，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.