Oxide supported metal catalysis, structure reactivity studies

氧化物负载的金属催化剂是非均相工艺的关键材料，从排放修复到碳氢化合物氧化再到燃料电池技术。这些催化剂通常包含纳米到微米大小的分散金属颗粒，分散在氧化物（如二氧化硅、氧化铝或氧化锆）的基体中。尽管氧化物负载的金属催化剂得到了广泛的应用，但仍有许多问题没有得到解答：载体的作用是什么？，哪些是活性位点？反应机制是什么？中间产物是什么？它们是如何干扰反应的？即使在燃料电池电催化剂中使用的极高负载情况下，有关活性位点、机制和中间体的问题仍不清楚。提出的研究计划的目标是通过建立结构-反应性关系和原位研究中间体来解决这些问题。由于支持材料的差异以及催化剂负载的巨大差异，低负荷和高负荷材料之间相互作用的潜力尚未得到认识。我们打算在分子水平上研究发生在氧化钇稳定氧化锆上的金属纳米颗粒上的过程，因为它们在多相催化和固体氧化物燃料电池工业中具有潜力。实验方法涉及多孔“真实”催化剂的制备和测试。使用衍射和显微镜技术对这些材料的电子和形态结构进行了充分的表征，并在反应堆或燃料电池装置中进行了活性测试。同时，利用光谱学和显微技术，在超高真空条件下对“模型”催化剂进行了研究。模型催化剂和实际催化剂的结构反应关系的比较，对理解和改进催化过程具有很好的潜力。该方法旨在为靶向制备具有所需性能的催化剂提供理论依据。

Oxide supported metal catalysts are key materials in heterogeneous processes ranging from emissions remediation to hydrocarbon oxidation to fuel cell technology. These catalysts generally involve disperse metal particles of nano to micrometer size dispersed in the matrix of an oxide such as silica, alumina or zirconia. Despite their widespread use, many questions remain unanswered for oxide supported metal catalysts: what is the role of the support?, what are the active sites?, what are the reaction mechanisms?, what are the intermediates and how do they interfere with the reaction? Even in the extremely high loading cases used in the electro-catalysts of fuel cells, issues regarding active sites, mechanism, and intermediates remain unclear.The objective of the proposed research program is to address some of these questions by establishing structure-reactivity relationships and studying intermediates in situ. The potential for interplay between low and high loading materials has gone unrecognized owing to differences in support material as well as dramatic differences in catalyst loading. We intend to study, at the molecular level, the processes occurring on metal nanoparticles supported on yttria stabilised zirconia due to their potential in heterogeneous catalysis as well as in the solid oxide fuel cell industry.The experimental approach involves the preparation and testing of porous "real" catalysts. These materials are fully characterised for electronic and morphological structure using diffraction and microscopy techniques and tested for activity in reactor or fuel cell setups. At the same time, "model" catalysts are studied under ultra high vacuum conditions using spectroscopy and microscopy. The comparison of structure-reactivity relationships obtained for model catalysts and for real catalyst has a good potential for the understanding and improvement of catalytic processes. The approach is meant to provide a rationale for targeting the preparation of catalysts with the desired properties.