Photochemistry of f-element ions

Published data on photochemical reactions of f-element compounds, namely, uranyl ion and lanthanide and actinide ions, are surveyed and analyzed. The types of reactions of photoexcited ions, reaction mechanisms, and analytical applications of the photochemical methods for the separation, isolation, and determination of f-elements are considered.     

A new approach of CeO_2 and La_2O_3 effects on the three-way catalysts containing low precious metals

A series of three-way catalysts (TWCs),containing a small amount of precious metals (PMs,including Pt,Pd and Rh) and a large amount of promoters CeO2 and La2O3,were prepared with different precursor compounds and various doped manners.Crystal phases,dispersion of cerium and lanthanum,textural structure and thermal stability of the catalysts were investigated by XRD,XPS and pore parameters determination.The catalytic performance was studied by the measurements of CO,C3H6 and NO conversions on dependence of temperature at stoichimetric number point (S=1.00),and from S=0.75 to 1.30 at 280℃ or 340℃ for fresh or aged samples,respectively.The correlation between the catalytic performance and the characteristics of fresh and aged samples were discussed.The results show that the sample,in which CeO2 and La2O3 are doped with mixed oxide powders,possesses poor dispersion and less thermal stability,and the conversions of NO and C3H6 are apparently lower than those of the samples aged at 850℃ The main reason is     

Co0.2/Ce1-xZrxO2催化剂的制备、表征及其催化碳烟燃烧反应性能

 采用微孔扩散-共沉淀法制备了不同 Ce/Zr 摩尔比的 Ce1-xZrxO2 (x = 0, 0.2, 0.4, 0.5) 固溶体, 并以此为载体用超声波助分散等体积浸渍法制备了 Co0.2/Ce1-xZrxO2 催化剂, 考察了催化剂中 Ce/Zr 比对其催化柴油车尾气碳烟颗粒物燃烧反应性能的影响. 结果表明, 在催化剂与碳烟颗粒松散接触条件下, Co0.2/Ce1-xZrxO2 催化剂催化碳烟颗粒物燃烧的活性非常高. 其中 Co0.2/Ce0.8Zr0.2O2 催化剂活性最高, T10, T50, T90 和 SmCO2 分别为 316 oC, 385 oC, 413 oC 和 99.9%. 这与目前文献报道的松散接触条件下活性最高的担载 Pt 催化剂相近. 应用 X 射线衍射、透射电镜、扫描电镜、紫外-可见漫反射和傅里叶变换红外光谱技术对 Ce1-xZrxO2 固溶体及 Co0.2/Ce1-xZrxO2 催化剂进行了表征. 结果表明, Ce1-xZrxO2 固溶体由纳米级小颗粒组成 (平均粒径在 10 nm 左右). 适量的 Ce/Zr 比有利于改善立方尖晶石型 Co3O4 在 Ce1-xZrxO2 固溶体表面的分散, 从而提高催化剂活性. 程序升温还原结果表明, Co0.2/Ce0.8Zr0.2O2 催化剂具有最优的低温还原特性, 与它具有最高的催化活性相一致.     

一种新奇的d-f异双核配合物[Fe(phen)_3]_2[FeCe(tiron)_3]·6H_2O的水热合成、晶体结构和磁性

硝酸铁,硝酸铈,邻菲咯啉(phen)和钛铁试剂(Tiron)通过水热方法合成了一种d-f异双核配合物[Fe(phen)3]2[FeCe(tiron)3]·6H2O,tiron=C6H2O8S2。X-射线单晶衍射分析表明,晶体属立方晶系,P213空间群,晶胞参数为:a=2.19409(4)nm,V=10.5624(3)nm3,Z=4,F(000)=4648,R1=0.0451,wR2=0.1077,S=1.072。在具有C3对称性的[FeCe(tiron)3]6-单元中,Fe髥与6个酚氧配位形成一个反三棱柱配位多面体,Ce髥则与3个桥联的酚氧μ2-O和3个磺酸基的氧形成另一个与FeO6共用底面的反三棱柱配位多面体CeO6。配阳离子通过phen-phen之间的π-π相互作用和与配阴离子间的静电引力等作用组装成一种三角梅状准主/客体型的超分子。在2~300K温度范围内测试了配合物的变温磁化率,结果表明,Ce髥-Fe髥之间存在典型的反铁磁性相互作用。     

Effect of sintering temperature on microstructure,electric and optical properties of Ce<Subscript>0.8</Subscript>Gd<Subscript>0.2</Subscript>O<Subscript>2−δ</Subscript> + 2 mol % TiO<Subscript>2</Subscript>

The effect of the sintering temperature of the Ce_0.8Gd_0.2O_2?δ + 2 mol % TiO₂ on its microstructure, electric, and optical properties was studied using the methods of x-ray spectroscopy, scanning electron microscopy (SEM), conductivity and ellipsometry. It is shown that the electrolyte lattice parameter decreases at an increase in the sintering temperature. The pattern of the sample surface obtained using the SEM method points to the dominating role of the sintering temperature in the formation of the electrolyte microstructure. Variation of optical properties as dependent on the synthesis temperature is also determined by the microstructure parameters of ceramics: presence of pores, formation of grain interfaces.     

辅酶Q10的合成

以2,3,4,5-四甲氧基甲苯为原料, 经溴化、生成格氏试剂后在碘化亚铜存在下与(E)-4-氯-2-甲基-1-苯磺酰基-2-丁烯缩合得到合成辅酶Q10的关键中间体6-(E-3'-甲基-4'-苯磺酰基-2'-丁烯基)-2,3,4,5-四甲氧基甲苯. 此中间体与茄尼基溴缩合、脱砜基化反应和氧化三步反应, 最终制得标题化合物辅酶Q10, 以2,3,4,5-四甲氧基甲苯计总收率达31.3%.     

正己烷在Pt-Ce促进的氧化硅担载的杂多酸金属氧酸盐上的异构化

制备了用于正己烷临氢异构化的氧化硅担载的Keggin型杂多酸和还原态Pt-Ce氧化物催化剂.这些混合氧化物催化剂或单独使用,或与氧化硅担载的杂多酸催化剂一起使用.用X射线衍射、傅里叶变换红外光谱、傅里叶变换拉曼光谱、热重和N2物理吸附等方法表征在氧化、还原态和催化实验后的催化剂状态.本文的目的是在最佳反应条件(反应温度、还原温度和流量等)下,筛选出具有最好异构化收率的催化剂.结果表明,还原氧化物的存在不但有利于消除积炭,而且在反应期间能有效地维持氧化硅担载杂多酸的结构.从这些催化剂样品中,可以找到具有更好异构化活性和选择性的催化剂.     

ChemInform Abstract: The Crystal Structures of m,o‐Ce3Pt4Sn6 and Ce1‐xPt6Al13+2x.

Single crystals of Ce₃Pt₄Sn₆ (I) and Ce_1‐xPt₆Al_13+2x (x = 0.207, (II)) are isolated by mechanical fragmentation of specimens grown from self‐fluxes (Sn or Al, resp.) by slow cooling from the melt.