中低温下混合导体透氧膜失效机理及对策研究

High operation temperature (usually > 800 oC) aroused many technology bottle-necks block the industrialization progress of the traditional mixed conducting oxygen permeable membranes technology. Although the technology bottle-necks are easy to be overcome under intermediate-low temperature (ILT) range (400~700 oC), the permeability of membranes is not stable under the temperature range. To solve the above dilemma, it is proposed to investigate the failure mechanisms and the countermeasures of mixed conducting membranes in the ILT range. Through the detailed theoretical analysis of the potential failure mechanisms, the oxygen permeation behaviors of several selected membranes materials are to be comprehensively investigated by using the new permeation model developed by the applicant of the project to explore the changes of the surface exchange resistances and the bulk diffusion resistance. Characterization instruments are to be used to observe the changes of the crystal structure, microstructure, defects, elemental composition, valence state and distribution before and after the oxygen permeation experiments under the ILT. Combined with the permeation experiments and the characterization data, the failure mechanisms are to be disclosed. The failure mechanisms of the different membranes will be classified and summarized, and let's the researchers find out the overall characters and the specification characters of the failure mechanisms to propose effectively schemes to overcome the failure of the mixed conducting membrane under the ILT. Finially,the structure characters of the ILT-stable mixed conducting membranes are attempted to be depicted to establish the theoretic and experimental foundations for the development of ILT-oxygen permeable membrane technology.

传统混合导体透氧膜因其高温操作(>800oC)而带来的技术瓶颈严重制约了其工业化进程，虽然中低温（400~700oC）条件下这些技术瓶颈容易被突破，但透氧膜渗透通量在该温度区间会快衰减。针对透氧膜技术发展中遇到的上述困境，拟开展混合导体透氧膜中低温失效机理及对策的研究。从理论分析可能的失效机理入手，详细研究具有代表性的透氧膜材料在中低温下的氧渗透行为，利用氧渗透模型对渗透过程进行模拟分析，探究膜表面交换阻力和体相扩散阻力随时间变化的关系。利用多种表征手段观测渗透前后膜表面和体相的晶体结构、显微结构、缺陷、元素组成、价态以及分布等的变化，探讨透氧膜在中低温下的失效机理。将不同膜材料的失效机理分类、归纳，找出膜失效的共性与特性，根据这些共性与特性反映出的物理化学特征，提出并验证能有效地克服膜失效的方案，并尝试描绘出中低温渗透性稳定的膜材料的结构特征，为发展中低温透氧膜技术奠定理论和实验基础。

传统混合导体透氧膜因其高温操作(>800ºC)而带来的技术瓶颈严重制约了其工业化进程，虽然中低温（400~700ºC）条件下这些技术瓶颈容易被突破，但透氧膜渗透通量在该温度区间会快衰减。针对透氧膜技术发展中遇到的上述困境，本项目开展了混合导体透氧膜中低温失效机理及对策的研究。从理论分析可能的失效机理入手，详细研究了具有代表性的透氧膜材料在中低温下的氧渗透行为，利用氧渗透模型对渗透过程进行了模拟分析，探究了膜表面交换阻力和体相扩散阻力随时间变化的关系。利用多种表征手段观测了渗透前后膜表面和体相的晶体结构、显微结构、缺陷、元素组成、价态以及分布等的变化，探讨了透氧膜在中低温下的失效机理。将不同膜材料的失效机理分类、归纳，找出了膜失效的共性与特性。发现对于相结构稳定的膜材料，膜材料中的微量杂质在低温下从膜体相向膜表面富集导致表面交换阻力显著增大导致；对于相结构不稳定的膜材料，相变和表面杂质富集共同导致了低温膜的低温快速衰减。根据这些共性与特性反映出的物理化学特征，提出了并验证能有效地克服膜失效的方案。即对于相结构稳定的膜材料，在膜表面涂敷多孔催化剂来容纳从膜体相扩散出的杂质，对于相结构不稳定的膜材料，除了在膜表面涂敷多孔催化剂，本项目提出了在膜材料晶界处引入纳米粒子抑制相变的方法。通过本项目的研究，我们尝试描绘出了中低温渗透性稳定的膜材料的结构特征，为发展中低温透氧膜技术奠定了理论和实验基础。