The role of interfaces in ceria-based multi-phase membranes for membrane reactors

膜反应器用二氧化铈基多相膜中界面的作用

• 批准号: 387282673
• 负责人: Dr.-Ing. Stefan Baumann
• 金额: --
• 依托单位: Gemeinschaftslabor für Elektronenmikroskopie (GFE)
• 依托单位国家: 德国
• 项目类别: Research Grants
• 财政年份: 2017
• 资助国家: 德国
• 起止时间: 2016-12-31 至 2022-12-31
• 项目状态: 已结题
• 来源: https://gepris.dfg.de/gepris/projekt/387282673?language=en
• 关键词: role; interfaces; ceria; based; multi

The application of catalyst-coated O2-permeable membrane reactors is an energy efficient alternative to the commercially applied methods of synthesis in the area of heterogeneous catalysis. During such treatments, the oxygen which is necessary for conversion is taken from air. O2- ions are transported straight to the catalyst through a gastight thin ceramic layer. This combines the two steps of air separation and chemical conversion in one process.As most of these conversions take place at temperatures between 200 and 500 °C, membranes with a specific permeation rate of roughly 1 mlN cm-2 min-1 in this temperature range are necessary to ensure a significant conversion rate. The permeation through a ceramic oxygen permeation membrane takes place by solid state diffusion and mainly depends on the ambipolar conductivity, the thickness of the membrane and the oxygen partial pressure gradient across the membrane.Ceramic composites with one mainly oxide ion conductive and one electron conductive constituent are promising candidates for this kind of application as these materials combine a high oxygen flux with high mechanical and chemical stability under reaction conditions. However, research efforts so far have been focused on the temperature regime above 700 °C. To reach a good permeation rate also in the lower temperature range, the main effort, apart from basic adaption of the composition, will be the optimization of the interfaces between the single constituents. The reason is that a variety of reactions occur at the interfaces, which have a fundamental impact on the oxygen transport through the membrane.In course of the present project the consortium plans to systematically investigate the chemical and physical characteristics of the different interfaces or rather of transport processes taking place at the interfaces of an acceptor doped CeO2-based composite material with a spinel phase as electron conductive constituent, where FeCo2O4 will be the initial material. A more precise comprehension of the processes at grain boundaries and triple phase boundaries is the key for the planned purposeful optimization of the composite material for catalytic applications, e.g. by micro structuration or adaption of the chemical composition of the different phases. The chosen composites are planned to serve as examples for a series of CeO2-based multiphase composites. The fundamental insights from these investigations will be used to reach technologically relevant permeation rates at intermediate temperatures and thus to open a broader field of application to the working concept of a membrane reactor.

在多相催化领域，应用催化剂涂层透氧膜反应器是一种替代商业应用的合成方法的能源效率高的方法。在这种处理过程中，转化所需的氧气是从空气中提取的。O2-离子通过气密的薄陶瓷层直接输送到催化剂上。这将空气分离和化学转化两个步骤结合在一个过程中。由于这些转化大多发生在200至500℃之间，因此需要在此温度范围内具有大约1mln cm-2min-1的比渗透速率的膜，以确保显著的转化率。陶瓷透氧膜的渗透是通过固相扩散进行的，主要取决于膜的双极导电性、膜的厚度和膜上的氧分压梯度。具有一个主要氧离子导电性和一个电子导电性的陶瓷复合材料具有很好的应用前景，因为这些材料在反应条件下结合了高氧通量和高机械和化学稳定性。然而，到目前为止，研究工作主要集中在700°C以上的温度范围。为了在较低的温度范围内达到良好的渗透速率，除了基本适应组成外，主要努力将是优化单一组分之间的界面。在本项目中，该联盟计划系统地研究不同界面的化学和物理特征，或者更确切地说，研究以尖晶石相作为电子传导组分的受主掺杂CeO2基复合材料界面上发生的传输过程，其中FeCo2O4将是初始材料。更准确地理解晶界和三相界处的过程是有计划、有目的地优化催化应用复合材料的关键，例如通过微观结构或调整不同相的化学组成。选定的复合材料计划作为一系列CeO2基多相复合材料的范例。从这些研究中得到的基本见解将被用来在中等温度下达到技术上相关的渗透率，从而为膜反应器的工作概念开辟更广泛的应用领域。