GOALI: Search for a Practical Perovskite-Based Three-Way Catalyst

催化剂中具有催化活性的金属颗粒逐渐变粗是催化剂随着时间的推移失去活性的根本原因之一。对于三向汽车废气催化剂，一个最近的现象，在新的贵金属掺杂钙钛矿配方中，氧化还原诱导金属的周期性再分散已经被提出作为减少这个问题的可能手段。最近的研究表明，这种现象在这些系统中仅发生在几纳米的距离上，这表明实用的钙钛矿基催化剂可能涉及超薄钙钛矿薄膜或涂层。为了评估这种催化剂的可行性，此次GOALI奖将在密歇根大学和福特研究与创新中心进行，在教授的指导下，将电子显微镜和模型平面和高表面积粉末催化剂的催化测量精心设计。潘小青和乔治·格雷厄姆以及罗伯特·麦凯布博士。具体目标包括观察在平面载体上的超薄钙钛矿薄膜中的自稳定或自再生催化剂行为，钙钛矿涂层高表面积粉末的生产，模型粉末催化剂体系中结构转化的动力学和详细化学势依赖的测量，钙钛矿基贵金属催化剂的催化表征，使用简单反应来探测三向催化活性。并最终对钙钛矿基贵金属粉末催化剂在现实条件下的耐久性进行评价。结构-性能关系测试的一个重要方面将是清楚地分配催化活性，无论是负载金属颗粒还是金属掺杂钙钛矿。更广泛的意义和重要性：汽车尾气催化剂目前占全球Pt和Pd需求的30-50%，相应的Rh需求更高，约为80%。由于这些金属在这种应用中的利用率在寿命结束时从未超过几个百分点，主要是由于颗粒粗化，因此即使是适度提高效率，在商业和科学上都具有巨大的意义。拟议的工作为密歇根大学的研究生和本科生提供了与福特汽车公司的催化剂研究人员及其供应商密切合作的机会，以实现这一目标，即通过开发实用的钙钛矿基三向催化剂来提高金属利用效率。

Abstract#1159240Pan, XiaoqingGradual coarsening of the catalytically-active metal particles in a catalyst is one of the fundamental reasons for loss of activity over time. For three-way automotive exhaust-gas catalysts, a recent phenomenon, the redox-induced cyclical re-dispersion of the metal in novel precious-metal-doped-perovskite formulations has been proposed as a possible means of reducing this problem. Recent work showing that this phenomenon occurs over distances of only a few nanometers in these systems suggests that a practical perovskite-based catalyst will likely involve ultra-thin perovskite films or coatings. In an effort to assess the viability of such a catalyst, this GOALI award covers a carefully designed combination of electron microscopy and catalytic measurements on model planar and high-surface-area powder catalysts to be conducted at University of Michigan and Ford Research and Innovation Center under the supervision of Profs. Xiaoqing Pan and George Graham and of Dr. Robert McCabe, respectively. Specific objectives include the observation of self-stabilizing or self-regenerative catalyst behavior in ultra-thin perovskite films on planar supports, the production of perovskite-coated high-surface-area powders, the measurement of kinetics and detailed chemical potential dependence of structural transformations in model powder catalyst systems, the catalytic characterization of perovskite-based precious-metal catalysts using simple reactions to probe three-way catalytic activity, and ultimately the durability assessment of perovskite-based precious-metal powder catalysts under realistic conditions. An important aspect of the structure-property relationship testing will be to clearly assign catalytic activity to either supported metal particles or metal-doped perovskite.Broader Significance and Importance: Automotive exhaust-gas catalysts currently account for 30-50% of the world-wide demand for Pt and Pd, and the corresponding demand for Rh is even higher, ~80%. Since the utilization of these metals in this application has historically never exceeded a few percent by end of life, due primarily to particle coarsening, the attainment of even a modest increase in efficiency would be of tremendous significance, both commercially as well as scientifically. The proposed work affords the opportunity for graduate and undergraduate students at University of Michigan to collaborate closely with catalyst researchers at Ford Motor Company and their suppliers in the pursuit of this goal, which is to improve metal utilization efficiency through the development of a practical perovskite-based three-way catalyst.