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

在本研究项目中，我们研究了新提出的电化学膜反应器系统的每个过程，并获得了以下结果。（1）研究了钡铁氧体（Ba-Fe系）的透氧性能。部分取代Ba的稀土金属以及碱土金属被发现稳定立方钙钛矿结构，即使在室温下。同时发现，氧渗透出现在较低的温度。用Ni、Mg或Zn部分取代Fe对改善氧渗透性是相当有效的。(2)Fe Mn基钙钛矿具有良好的透氧性和抗还原稳定性，可作为一种稳定的透氧膜应用于甲烷部分氧化和甲烷还原NO的膜反应器中。此外，Ba/Sr/Fe基钙钛矿被认为是最优秀的透氧材料之一。（3）Sr、Fe掺杂的LaGaO_3（LSGF）具有较高的电导率、透氧速率和化学稳定性，可用于甲烷部分氧化的透氧膜。LSGF在较宽的Po_2范围和温度下以空穴导电为主。此外，还研究了不同氧化物的透氧速率，发现掺杂Gu的Pr_2NiO_4具有较高的空气透氧速率。（4）多孔圆盘的制备尝试在其上制备薄膜以改善混合导电钙钛矿型氧化物的透氧性。草酸盐前体方法被发现，即使在升高的温度下，得到具有窄的孔径分布的多孔盘。通过草酸盐前驱体方法获得的盘显示出高的氮渗透性，对于实际应用是可行的。

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.