钛酸锶基混合导体膜的结构调控及化学反应条件下的透氧性能和稳定性研究

Methane conversion in an oxygen permeable membrane reactor is of theoretic and realistic significance. It has great advantage to put the partial oxidation of methane and water dissociation on two sides of the oxygen permeable membrane based on coupling strategy. However, common Co-based and Fe-based oxygen permeable membranes have bad stability under above-mentioned condition. The key problem is the improvement of stability and enhanced oxygen permeability of membrane under the condition of chemical reactions. The emphasis of this proposal is putting on tailoring the structure of strontium titanate-based mixed conductor membrane and investigating the oxygen permeability and stability of oxygen permeable membrane during the course of partial oxidation of methane reaction. In this project, we prepare the membrane with different structure by tuning the different ratio of Ba and Mg. Here, the partial substitution of Sr by Ba can decrease the activation of migration energy of oxygen vacancies. However, Mg substitutes for Ti can increase the concentration of mobile oxygen vacancies. The electron and oxide-ion conductivity of the membrane will be investigated and the relationship between structure and electron/oxide-ion conductivity of the membrane are illustrated. In addition, We dope different content Y or Ce to the above-mentioned strontium titanate-based membrane. The effect of the nanoparticles at the grain boundary on the oxygen permeability membrane and microstructure will be discussed. Furthermore, the stability and oxygen permeability of membrane will be studied in the condition of partial oxidation of methane. The influence of microstructure on stability and oxygen permeability of membrane will be established in the condition of chemical reaction. It is believed that the planned research work on such kinds of membranes will be highly valuable for the efficient conversion of methane.

基于透氧膜反应器的甲烷转化技术方面的研究具有重要的理论和现实意义，将甲烷部分氧化反应和水分解反应耦合在透氧膜两侧具有很大优势，但常用的Co基和Fe基透氧膜在上述条件下稳定性较差，提高反应条件下膜的稳定性和透氧能力是目前函待解决的关键问题。本项目重点开发SrTiO3基膜材料，并考察其在甲烷转化条件下的透氧性能和稳定性。通过调变Ba和Mg在SrTiO3中的掺杂量，分别调控氧空位浓度和迁移能，考察其电子和氧离子电导率，揭示掺杂SrTiO3的结构和电子/氧离子电导率的内在联系；在上述掺杂SrTiO3中引入不同含量的Y或Ce，考察晶界纳米颗粒对膜材料的微结构和透氧性能的影响，同时研究其在甲烷部分氧化反应条件下的透氧性能和稳定性，阐明化学反应条件下微结构对透氧性能和稳定性影响规律；从而获得化学反应条件下稳定性和透氧性能高的混合导体膜，相信此类透氧膜的研究为将来甲烷的高效转化提供有力帮助。

针对常用的Co基和Fe基透氧膜在耦合甲烷部分氧化反应和水分解反应时存在稳定性较差的问题，开发了Ce掺杂改性的Fe基透氧膜和Ba、Mg、Zr掺杂改性的SrTiO3基透氧膜材料。分别通过调变掺杂元素的含量调控膜材料的稳定性和渗透性能，并在不同反应气氛下进行了稳定性和渗透性能考察。研究发现Ce掺杂提高了Fe基透氧膜的抗还原能力，Ba、Mg、Zr掺杂的SrTiO3基透氧膜拥有良好的透氧性能并表现出优于Fe基透氧膜的抗还原能力，在实际反应气氛中运行200小时后未发生明显相结构和成分的变化。研究成果将为甲烷的高效转化提供有力帮助。