纳米纤维基负载型双相透氧膜的制备及其理论研究

Oxygen permeation ceramic membranes exhibit considerable potentials in oxygen separation and the conversion of light hydrocarbon into high-value chemicals due to their low-cost and energy-effective properties. The development of supported oxygen permeable membranes can accelerate their industrial application which has important economic significance and social value. The current project aims to prepare self-supported oxygen permeable membranes by chemical etching method based on high stable dual-phase oxygen permeable membrane materials and reveal the interaction mechanism of surface catalytic modification and the performance of oxygen permeation membranes. In this project, one-dimensional nanofibrous powders of oxygen permeation membranes will be initially synthesized via an electrospinning method. The self-supported oxygen permeable membranes with porous substrate and ultra-thin dense membrane layer will be then prepared by a chemical etching method. The dependence of oxygen permeable membrane performance on nano-fibrous structure and technological parameter of chemical etching will be investigated in detail. The systematical preparation method of self-supported oxygen permeable membranes can be obtained. Furthermore, porous substrate can be modified through a sol-gel method so that the catalysts can be effectively loaded into it. The relationship of porous microstructure, activation of oxygen molecules and oxygen permeation mechanism can be demonstrated by means of a series of characterizations such as SEM, XPS, etc. and chemical simulation software. This work will provide a theoretical basis for preparing supported oxygen permeable membranes and relative surface modification of oxygen permeation membranes, which have an important significance in inorganic membrane separation and membrane catalysis, etc.

透氧陶瓷膜在氧气分离、低碳烃转化等方面具有低成本、低能耗的优势，而开发负载型透氧膜将有利于促进透氧膜的实用化，具有重要的经济意义与社会价值。本项目旨在基于高稳定性双相透氧膜材料采用化学刻蚀法制备负载型透氧膜，并揭示支撑体催化剂修饰与透氧膜性能之间的影响机制。实验首先利用静电纺丝技术制备一维纳米纤维双相透氧膜粉体材料，然后通过化学刻蚀法一步制备具有多孔支撑体和超薄致密膜层的负载型透氧膜，重点研究透氧膜纳米纤维粉体微观结构、化学刻蚀工艺参数与透氧膜渗透性能之间的依赖关系，建立负载型透氧膜的系统制备方法；进而利用溶胶预修饰优化透氧膜载体的孔道微结构并进行膜反应催化剂活性组分的有效负载，采用SEM、XPS等微观表征与化学软件模拟相结合的手段阐明催化剂微观负载结构-氧分子活化-氧渗透机理之间的构效关系。该工作将为制备负载型透氧膜及表面修饰改性提供理论指导，其在无机膜分离和膜催化等领域具有重要意义。

混合导体透氧陶瓷膜在氧气分离、甲烷部分氧化制合成气、甲烷氧化偶联制乙烷或乙烯、燃料电池阴极材料等领域具有潜在的应用价值。随着我国对低碳经济、能源安全和环境保护的日益重视，人们迫切希望能够利用新兴技术提高现有能源利用效率，有效治理环境污染，而混合导体透氧膜及相关膜反应器技术恰好在上述领域可以弥补或升级传统技术，降低能耗和消除环境污染。然而当前发展的透氧膜材料在稳定性和透氧量两个指标上相互矛盾，难以同时满足膜稳定性与透氧量同步提高的工业要求。本研究旨在开发稳定性与透氧量兼具的负载型双相透氧膜组件与透氧膜新材料。在透氧膜组件设计开发中，本项目基于双相透氧膜材料的高稳定性，通过化学刻蚀方法制备了负载型双相透氧膜组件。将Ce0.85Sm0.15O1.925/Sm0.6Sr0.4Al0.3Fe0.7O3-d(SDC/SSAF)双相透氧膜功能透氧膜层厚度降到了50-100um, 本项目制备的负载型双相透氧膜是以多孔萤石相SDC为支撑体, 高稳定SDC/SSAF萤石-钙钛矿双相材料为透氧膜层，950oC透氧量达到了0.43ml.min-1.cm-2，对比研究表明SDC/SSAF负载型双相透氧膜组件较非负载的双相透氧膜在相同测试条件下透氧量提高近1倍, 达到了本项目的预期目的。基于透氧膜稳定性与透氧量同步提高的工业需求，本项目进一步拓展开发和系统研究了两类新型透氧膜材料：钙掺杂Ba0.33Sr0.33Ca0.33Co0.8Fe0.2O3-d(BSCCF)钙钛矿材料和富铈BaCe0.15CoxFe1-xO3-d钙钛矿透氧膜材料。项目中钙掺杂钙钛矿透氧膜材料具有良好的耐CO2性能，透氧量达到了1.5 ml.min-1.cm-2。富铈BaCe0.15CoxFe1-xO3-d达到了结构稳定性和较高的透氧量的有机结合，项目系统探讨了钙铈等掺杂离子与透氧膜材料综合性能（稳定性透氧量）之间的构效关系。透氧量和稳定性是制约混合导体透氧膜应用的两个关键因素，只有兼具高稳定性和高透氧量的透氧膜组件才能应用于工业化生产，本项目开发的负载型双相透氧膜SDC/SSAF组件和两类新型透氧膜材料都具有较好的稳定性与透氧量，本项目研究为新型透氧膜组件的结构设计与新材料开发奠定了较好的研究基础。