Development of Oxidation Reactor Using Solid Electrolyte Cell with Catalytic Electrode of Perovskite-type oxide

将固体电解质氧化反应器应用于甲烷氧化偶联反应。研究结果如下：1.通过固体电解质的氧离子在银催化剂电极上的反应性比从气相中吸附的氧更强。在Ag电极上，传输体系中C_2化合物的生成速率是预混合体系中的10倍左右; 2.用于氧化偶联的氧的比例很小，并且与电极材料密切相关; 3.在LaCoO_3电极上，完全氧化占主导地位，几乎没有未反应的氧。这些结果表明，参与氧化偶联反应的氧活性物种不同于<2->在固体电解质中扩散的氧离子。4.由碱土金属Ca、Sr、Ba和过渡金属Ti、Zr、Ce组成的钙钛矿型氧化物在氧化偶联反应中具有很高的催化活性。这些复合氧化物非常稳定，而碱土金属的单一氧化物在此反应中转变为碳酸盐. A位离子在该反应中起重要作用，而以前的研究发现B位离子起重要作用。6.发现氧化物单位表面积的催化活性与氧离子和金属离子之间距离的位移有明显的相关性。

A solid electrolyte oxidation reactor has been applied to the oxidative coupling reaction of methane. Findings from this investigation are as follows:1.The oxygen ion passing through the solid electrolyte was more reactive over Ag catalyst electrode than the adsorbed oxygen from the gas phase. Over Ag electrode, C_2 compounds were formed at the rate of about ten times larger in the transport system than in the premixture system.2.The fraction of oxygen utilized to the oxidative coupling was rather small and strongly dependent on the electrode material.3.Over LaCoO_3 electrode, complete oxidation predominantly proceeded with little amount of unreacted wxygen. These results suggested that the oxygen active species participating the oxidative coupling reaction are different from the oxygen ions, O^<2->, diffusing through the solid electrolyte.4.Many of the perovskite-type oxides made from such an alkaline earth metal as Ca, Sr, Ba and a transition metal, Ti, Zr, or Ce had high catalytic activity in oxidative coupling reaction. These complex oxides were very stable whereas the single oxide of alkaline earth metal changed to carbonate in this reaction.5. The A-site ion played an important role in this reaction in contrary to the previous finding that the B-site ion did.6.A clear correlation was found between the catalytic activity per unit surface area of oxide and the displacement of the distance between an oxygen ion and a metal ion.