Study on the self-packing of SnO2 nanoparticles at the air-hydrosol interface and its composite LB films with arachidic acid

SnO2 nanoparticles were found to self-pack at the air-hydrosol interface and form a nanoparticulate film. The self-packed films were observed under a Brewster angle microscope, and investigated by recording the time evolution of surface pressure and pi-A isotherms. The results show that SnO2 nanoparticles take 3 h to form a complete film at the air-hydrosol interface. Composite monolayers of SnO2 and arachidic acid were obtained by spreading arachidic acid onto a fresh hydrosol surface. Composite Y-type LB films were transferred from the air-hydrosol interface onto substrates, and characterized by FTIR, UV-vis, X-ray diffraction spectroscopy and TEM techniques. The results show that the composite films have good structure, with SnO2 nanoparticles uniformly and compactly distributed in the arachidate matrix. (C) 1998 Elsevier Science S.A. All rights reserved.

Catalysis of the rare earth containing mixed oxides Ln(2)CuO(4) in phenol hydroxylation

Mixed oxides Ln(2)CuO(4+/-lambda)(Ln = La, Pr, Nd, Sm, Gd) with K2NiF4 structure were prepared. Their crystal structures were studied with XRD and IR spectra. Meanwhile, the average valence of Cu ions and nonstoichiometric oxygen (lambda) were determined through chemical analyses. Catalysis of the above-mentioned mixed oxides in the phenol hydroxylation was investigated. Results show that the catalysis of these mixed oxides has close relation with their structures and composition. Substitution of A site atom in Ln(2)CuO(4+/-lambda) has a great influence on their catalysis in the phenol hydroxylation.

活性炭酸处理对CuO／C催化剂上NO还原反应的影响

４种国产活性炭被用于ＮＯ还原反应；其中，山楂核炭和山桃核炭具有较高的ＮＯ还原转化率。实验发现，表面含氧基团－ＣＯＯ－对话性炭自身的还原性和对ＮＯ的还原活性有根重要的影响。对表面富－ＣＯＯ－基团的活性炭，稀盐酸处理使表面－ＣＯＯ－显著分解。浓硝酸处理使活性炭表面含氧量及－ＣＯＯ－基团都明显增加。这是浓硝酸处理使活性炭在较低反应温度下产生较高ＮＯ还原转化率的重要原因。对原始活性较差的煤质炭，这种作用表现得更为明显。

活性炭的表面化学性质及对CuO/C催化剂上NO还原性能的影响

活性炭是一种十重要的吸附剂和催化剂载体.它属于微晶结构,主要在低衍射角处产生一个比较大的弥散峰,因而人们尚不能够获得关于活性炭的清晰的空间结构特征.一般认为,活性炭的含氧量是影响其化学性质的一个重要因素.而含氧量和含氧基团分布与活化方式有关.遗憾的是,也还不能通过活化方式控制含氧量和含氧基团分布.目前,关于这些基团的组成和分布在催化剂制备的某些关键步骤中和催化反应中的行为都还知道得很少.本工作选取了4种市售国产活性炭:椰壳炭、山楂核炭、山桃核炭和煤质炭.实验表明,当活性炭本身做催化剂时,含氧基团起到了活性中心作用;在制备负载催化剂的浸渍阶段,含氧基团起着成核中心作用,含氧基团的分布可以影响金属离子的分散度.1 实验部分1.l 反应性能评价以等体积浸渍法制备担载量6.25%质量分数硝酸铜/活性炭催化剂.首先室温下真空干燥24h,然后烘箱中65℃下烘4h,再120℃下烘6℃.性能评价在连续流动微型反应装置上进行.石英反应管内径8mm,催化剂用量500mg(20～35目).反应前催化剂在He气中200℃下处理0.5h,然后350℃下热分解1h.反应气NO浓度1.5%摩尔分数(配在He气中),F/W=50mL/...

CuO／活性炭和Fe_2O_3／活性炭催化还原NO

ＣｕＯ／活性炭和Ｆｅ_２Ｏ_３／活性炭催化还原ＮＯ高志明，赵震，杨向光，吴越（中国科学院长春应用化学研究所长春１３００２２）关键词活性炭，还原，ＮＯ，氧化铜，氧化铁目前，对固定源的ＮＯ处理是采用Ｖ２Ｏ５／ＴｉＯ２作催化剂，ＮＨ３作还原剂的选择催化还原方...

超微Y_2O_3、CuO和BaCO_3粉末的制备

本文采用固体草酸作沉淀剂,沉淀样品在水蒸汽气氛下焙烧分解,制成超微CuO、Y_2O_3和BaCO_3。用热分解法探讨其在水蒸汽下的分解机理,X射线衍射、红外光谱分析和元素分析对产物组成进行鉴定。通过电镜观察,超微粒子的粒径为:Y_2O_30.01～0.02μm、CuO0.02～0.03μm、BaCO_3～0.1μm。用空气吸附法测定其比表面积分别为146m~2g~(-1)、80m~2g~(-1)、20m~2g~(-1)。