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Nanometer perovskite LaMnO3 λ, La0.6Ce0.4MnO3 λ and La0.6Sr0.4MnO3 λ were prepared by citric acid-aide dsol-gel method. The effects of Ce, Sr on the structure and properties of nanometer perovskite were studied through DTTGA, XRD, TEM and BET analyses. The results show that, by sol-gel method, LaMnO3 λ, La0.6Ce0.4MnO3 λ and La0.6Sr0.4MnO3 λ were made with average particle size of about 60, 100 and 30 nm, respectively. After partially substituting Sr on La positions in LaMnO3 λ, it is found that Sr is located at the perovskite lattice so as to reduce the formation temperature of the perovskite. As a result, the perovskite has a smaller particle size and larger specific surface area. On the contrary, it is difficult for Ce to enter the perovskite lattice. Ce exists mostly in the form of CeO2 as partially substituting La in LaMnO3 λ. The formation temperature of the perovskite increases, and the catalyst containing CeO2 presents a larger particle size and less specific surface area. 相似文献
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The effect of Au on the reducibility of La-Ce-Mn catalyst was studied in the synthetic exhaust gas mixture containing 10% oxygen. The characteristics of samples were analyzed by BET, SEM, XRD and activity evaluation. The resuits show that, in lean combustion, the performance of perovskite-type catalysts is evidently enhanced through adding Au, and specially a satisfying reducibility for NOx is demonstrated between 300~500℃. The catalytic activity of samples increases with the loading amount of Au, and the maximum conversion rate for NOx decomposition reaches up to 47% in 360~400℃. Moreover, the dispersivity and uniformity of the surface distribution of perovskite with Au have an important influence on the catalytic activity. 相似文献
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等离子喷涂氧化铝涂层的结构与性能研究 总被引:17,自引:1,他引:17
采用等离子喷涂技术 ,在 Fe Cr Al RE合金基体表面制备铝钛涂层和氧化铝涂层 ,与浸渍法制备的氧化铝涂层进行比较。利用 XRD、SEM、BET和超声振动等分析测试技术 ,对涂层的微观结构与表面特性进行研究。结果表明 ,加入适量的 Ce O2 、L a2 O3 、Zr O2 、Si O2 后 ,氧化铝喷涂涂层的表面组成相主要保持为 γ- Al2 O3 ,其蜂窝状多孔结构上堆积了大量弥散分布的纳米微粒 ;这种复合结构既保证了涂层与载体牢固的结合 ,表现出优于氧化铝浸渍涂层的抗振性与抗热震性 ,又使得涂层的几何比表面达到 32 .1m2 / g,大大超过铝钛喷涂涂层。因此 ,可用等离子喷涂工艺制备氧化铝涂层 ,作为承载活性组分的分散层 ,用于摩托车的金属载体排气催化剂 相似文献
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