Effect of Sr and Ce on Synthesis of Nanometer Perovskite LaMnO3＋λ

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.     

柴油车微粒捕集器过滤材料研究进展

论述了几种类型过滤材料的特性及在柴油车微粒捕集器中的应用状况，分析了过滤材料面临的几个主要问题，并展望了其应用前景。     

某高速公路预应力管桩冲桩对路基液化影响的监测与分析

通过监测预应力管桩动力冲桩过程中路基内孔隙水压力的变化,分析了冲桩振动对砂质路基液化的影响情况,从而为类似场地及工作条件下选择适当的压桩工法提供依据。     

Improvement of Gold to Reducibility of La-Ce-Mn Catalyst under Lean Combustion

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.     

稀土在汽车尾气净化器中的作用

本文根据国内外有关研究报道,综述了稀土在汽车尾气净化器中的作用,展望了稀土在汽车尾气净化器领域的发展前景.     

我国稀土汽车尾气净化器应用现状及发展趋势

本文介绍了2000年以来稀土在汽车尾气催化剂中的研究与应用现状,以及有关稀土汽车尾气净化器发展趋势。给出了一些关于机动车尾气排放污染控制的法规数据,提出了一些十五期间我国稀土汽车尾气净化器的发展思路,以及有关发展我国稀土汽车尾气净化器的政策和措施建议。     

等离子喷涂氧化铝涂层的结构与性能研究

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