In-situ Methods to Determine High Oxygen Deficits in Ceria-Zirconia Mixed Oxides for Exhaust Gas Aftertreatment

废气后处理用氧化铈-氧化锆混合氧化物中高氧缺损的原位测定方法

• 批准号: 315514625
• 负责人: Professor Dr.-Ing. Holger Fritze
• 金额: --
• 依托单位: Arbeitsbereich Sensorik von Hochtemperaturprozessen
• 依托单位国家: 德国
• 项目类别: Research Grants
• 财政年份: 2016
• 资助国家: 德国
• 起止时间: 2015-12-31 至 2022-12-31
• 项目状态: 已结题
• 来源: https://gepris.dfg.de/gepris/projekt/315514625?language=en
• 关键词: situ; Methods; Determine; Oxygen; Deficits

Besides its good catalytic properties, ceria provides a high oxygen storage capacity and is, therefore, highly suited for the application in storage catalysts and steam reformers. To in-crease the stability, ceria-zirconia mixed oxides are used. A comparatively high oxygen defi-ciency can be established, which has only been studied with indirect or elaborated laboratory methods. To make the above-mentioned systems more effective, the oxygen deficiency of ceria-zirconia mixed oxides must be monitored in situ. At this point, resonant nano balances and microwave-based approaches represent promising opportunities. The latter are already studied in automotive exhausts without, however, detailed knowledge of the fundamental materials properties. Further, the defect chemical mechanisms of the ceria-zirconia mixed oxides must be better understood, especially for high oxygen deficiencies.Therefore, the aim of this project is to provide from a materials science point of view the re-quirements for in situ analysis of the oxygen deficiency in ceria-zirconia mixed oxides of se-lected compositions. For this purpose, a direct measurement of the oxygen deficiency by means of a resonant high-temperature nano scale (TU Clausthal) and an indirect microwave-based method (Univ. Bayreuth) are envisaged. The influence of the electrical and mechani-cal properties of mixed oxides on frequencies and damping is used. The measurements are performed at high temperatures that allow a fast adjustment of the defect equilibrium.The preliminary work confirms, in principle, the suitability of the proposed methods to investi-gate the oxygen deficiency. Besides the development of the new in situ methods, the stability limits of the highly oxygen deficient mixed oxides should be determined by simultaneous ap-plication of conventional methods. The properties of interest include the defect and transport mechanisms as well as the effect of sample morphology. Further, the measurement of other thermo physical properties of the mixed oxides such as chemical expansion is anticipated in order to evaluate the mechanical stability. Finally, the microwave dielectric properties of the ceria-zirconia mixed oxides should be determined and included in a model that describes the microwave properties of three-way-catalysts under operation.The scientific approach includes the preparation of common samples and their investigation in both laboratories. Furthermore, the data should be correlated and included in a common model. Thereby, the project takes advantage of the complementary competencies of both partners. Partial redundancy of the data improves their reliability. The expected results broaden the understanding of the defect chemistry of highly oxygen deficient ceria-zirconia mixed oxides and enable the in situ monitoring of related high-temperature systems.

除了具有良好的催化性能外，二氧化铈还具有很高的储氧能力，因此非常适合用于储氧催化剂和蒸汽转化炉。为了提高稳定性，采用了氧化铈-氧化锆混合氧化物。可以建立一个相对较高的氧缺乏，这只能通过间接或详细的实验室方法进行研究。为了使上述系统更有效，必须对氧化铈-氧化锆混合氧化物的缺氧进行现场监测。在这一点上，谐振纳米天平和基于微波的方法代表了有希望的机会。后者已经在汽车尾气中进行了研究，但是，没有详细了解基本材料特性。此外，必须更好地了解氧化铈-氧化锆混合氧化物的缺陷化学机制，特别是对于高氧缺乏。因此，本项目的目的是从材料科学的角度提供对选择性成分的氧化铈-氧化锆混合氧化物的氧缺乏性进行原位分析的要求。为此，设想了通过共振高温纳米尺度（TU Clausthal）和间接基于微波的方法（Univ. Bayreuth）直接测量氧缺乏症。研究了混合氧化物的电学和力学性能对频率和阻尼的影响。测量是在允许快速调整缺陷平衡的高温下进行的。初步工作原则上证实了所提出的研究缺氧的方法的适用性。除了开发新的原位方法外，还应同时采用常规方法确定高氧缺乏混合氧化物的稳定性极限。感兴趣的性质包括缺陷和输运机制以及样品形貌的影响。此外，为了评估混合氧化物的机械稳定性，预计将测量混合氧化物的其他热物理性质，如化学膨胀。最后，确定氧化铈-氧化锆混合氧化物的微波介电性能，并将其纳入描述三元催化剂微波性能的模型中。科学的方法包括制备普通样品并在两个实验室进行调查。此外，数据应该相互关联并包含在一个公共模型中。因此，该项目利用了双方的互补能力。数据的部分冗余提高了数据的可靠性。预期的结果拓宽了对高度缺氧的铈锆混合氧化物缺陷化学的理解，并使相关高温系统的现场监测成为可能。