Construction of new electrochemical-membrane-reactor system for simulutaneous environmental purification/chemical conversation

在这个研究项目中，我们对新提出的电化学膜反应器系统的各个过程进行了研究，得到了以下结果。(1)研究了钡铁氧体（Ba-Fe体系）的透氧性能。稀土金属和碱土金属对钡的部分取代，即使在室温下也能稳定立方钙钛矿结构。在较低的温度下还发现了氧的渗透现象。用Ni、Mg或Zn部分取代Fe对改善氧透性是非常有效的。(2)Fe/ mn基钙钛矿具有良好的透氧性和稳定性，可作为催化甲烷部分氧化和甲烷还原NO的膜反应器中较为稳定的透氧膜。此外，Ba/Sr/ fe基钙钛矿是最优异的透氧材料之一。(3)锶铁掺杂LaGaO_3的钙钛矿氧化物（LSGF）具有较高的导电性、透氧速率和化学稳定性，可用于CH_4部分氧化的透氧膜。在较宽的Po_2范围和温度下，空穴传导在LSGF中占主导地位。此外，还研究了氧在各种氧化物中的渗透速率，发现掺有Gu的Pr_2NiO_4能使氧从空气向He的渗透速率较高。(4)为了提高混合导电钙钛矿型氧化物的透氧性，尝试在多孔盘的制备上制备薄膜。草酸盐前驱体法即使在高温下也能得到孔径分布窄的多孔圆盘。草酸盐前驱体法制备的圆盘具有较高的氮透性，在实际应用中是可行的。

In this research project, we investigated each process of the newly proposed electrochemical membrane-reactor system and obtained the following results.(1)Oxygen permeation property of the barium ferrites(Ba-Fe system) was examined. Partial substitution of Ba by rare earth metals as well as alkaline earth metals was found to stabilize cubic perovskite structure even at room temperature. It was also found that oxygen permeation appeared at lower temperature. Partial substitution of Fe by Ni,Mg,or Zn was quite effective for improvement of oxygen permeability. (2)Fe/Mn-based perovskites exhibited oxygen permeability and high stability against the reduction, and could be used as quite stable oxygen permeable membranes in the membrane reactors catalyzing the partial oxidation of methane and the reduction of NO by methane. In addition, Ba/Sr/Fe-based perovskites was found to be one of most excellent oxygen permeable materials. (3)Perovskite oxide of LaGaO_3 doped with Sr and Fe(LSGF) was found to exhibit high electrical conductivity, oxygen permeation rate and chemical stability, and this LSGF could be used for oxygen permeation membrane for CH_4 partial oxidation. Hole conduction is dominant in LSGF in wide Po_2 range and temperature. In addition, oxygen permeation rate in various oxides was investigated and Pr_2NiO_4 doped with Gu was found to give high oxygen permeation rate from air to He. (4)Preparation of porous disk was attempted to fabricate thin films on it for the purpose of improving oxygen permeability of mixed conductive perovskite-type oxides. Oxalate precursor method was found to give porous disks with a narrow distribution of pore diameter even at elevated temperature. The disks obtained by the oxalate precursor method showed high nitrogen-permeability feasible for practical applications.