Materials World Network: In-Situ Investigation of Model Multi-Component Catalyst Systems

该奖项是根据2009年美国复苏和再投资法案（公法111-5）资助的。这是麻省理工学院（MIT- USA）和拜罗伊特大学（UB- Germany）的一个联合项目。在过去的三十年里，催化剂在减少90%以上的汽车排放方面发挥了核心作用，但这一进展在很大程度上受到了现象学和“试错”方法的阻碍。因此，用于车载诊断应用的催化剂建模和优化的方法受到了抑制。该项目旨在更好地了解催化剂材料的性质及其与衬底和气体的相互作用。这样的理解将推动催化剂科学的发展，并提高设计催化剂的能力，以改善其功能。这有可能影响广泛的商业战略行业，包括石化催化裂化、蒸汽重整、标准化学品合成（氨、硫酸）、燃料电池电极，所有这些都依赖于非均相催化剂。鉴于对环境的关注，这项工作非常适合年轻学生，并且在麻省理工学院目前的水平上扩展了针对K-12学生的扩展计划。该计划旨在吸引本科生，并为研究生提供在全球科学环境中工作的经验。采用跨学科方法，利用多种表征工具，在实际操作条件下，获得催化剂系统中所有组件（支撑，存储组件，贵金属）的行为和相互作用的详细知识。模型结构由贵金属、氧/氮氧化物存储和支撑材料组成，通过气相或溶液方法沉积在氧化物衬底上，形成三层结构，允许系统控制表面积、三相边界和扩散长度。通过微球模板和喷墨印刷（MIT）实现了表面面积和可控的中、纳米孔隙度。采用库仑滴定法、电子/离子电导率法、复阻抗法和晶体微天平等方法，研究了固溶体形成/掺杂改性后的存储材料的缺陷化学性质和氧交换性能。此外，在两个实验室中应用了表面敏感测量，包括功函数（MIT）， XPS和DRIFT （UB）。差动反应器研究（UB）提供了所需的整体催化剂性能输入，而低热质量陶瓷微热板允许在汽车尾气中经历的那种程序化的快速热漂移。模型描述了各种催化剂系统组件的相互作用被开发和测试。模型系统的电响应作为一种研究工具和诊断催化剂原位性能的手段是有意义的。一个核心组成部分是学生和工作人员的广泛交流，提供了学习新的实验和建模方法的机会，并从全球角度深入了解如何进行研究。

This award is funded under the American Recovery and Reinvestment Act of 2009 (Public Law 111-5).This is a joint project between the Massachusetts Institute of Technology (MIT- USA) and the University of Bayreuth (UB- Germany). Catalysts have played a central role in reducing automotive emissions by over 90% over the past three decades but progress is slowed by largely a phenomenological, "trial-and-error" approach. As a consequence, means for rationalizing the modeling and optimization of catalysts for on-board diagnosis applications has been inhibited. This project aims to obtain an improved understanding of the catalyst materials properties and their interactions with substrate and gases. Such understanding will advance the science of catalysts as well as improve the ability to engineer catalysts towards improved functionality. This has the potential for impacting a broad range of commercially strategic industries including petrochemical catalytic cracking, steam-reforming, synthesis of standard chemicals (ammonia, sulfuric acid), & fuel cell electrodes, all of which depend on heterogeneous catalysts. Given the focus on environment, this work is ideally suited for young students and an outreach program for K-12 students is expanded under this program from present levels at MIT. The program is used to attract undergraduates and to provide graduate students experience working in a global scientific environment.An interdisciplinary approach is applied which utilizes multiple characterization tools, under realistic operating conditions, to achieve a detailed knowledge of the behavior and interplay of all the components within the catalyst system (support, storage component, noble metal). Model structures composed of noble metal, oxygen/NOx storage and support materials are integrated in three-layer arrangements featuring films deposited by vapor or solution methods onto oxide substrates allowing for systematic control of surface area, triple phase boundary and diffusion lengths. Surface area and controlled meso- and nano-porosity are achieved by microsphere templating and ink-jet printing (MIT). The defect chemistry and oxygen exchange properties of the storage materials, to be modified by solid solution formation/dopants, is examined by coulometric titration, electronic/ionic conductivity, complex impedance and crystal microbalance methods. Additionally, surface sensitive measurements, including work function (MIT), XPS and DRIFT (UB), are applied in the two laboratories. Differential flow reactor studies (UB) provide needed overall catalyst performance input, while low thermal mass ceramic micro hot-plates allow for programmed rapid thermal excursions of the type experienced in automotive exhausts. Models describing the interactions of the various catalyst system components are developed and tested. The electrical response of the model system is of interest as an investigative tool and as a means of diagnosing catalyst performance in situ. A central component is the extensive exchange of students and staff providing opportunities to learn new experimental and modeling methods and to gain insight into how research is approached from a global perspective.