用ESR方法研究Sn-Mo氧化物固溶体形成的机理

本文研究了Sn-Mo混合氧化物催化剂的活性与焙烧温度的关系。对Sn_(0.975)Mo_(0.025)催化剂进行了不同焙烧温度的ESR研究,跟踪观察了Sn-Mo混合氧化物固溶体随焙烧温度变化的形成过程。结果表明,焙烧温度在100—300℃之间,钼以钼酸铵微晶高度分散在氧化锡表面;300—550℃时,随温度升高钼逐渐向氧化锡体相扩散;550℃时可能形成嵌入型固溶体,催化活性最好;600℃开始形成置换型固溶体,Mo以Mo~(5+)形式取代氧化锡晶格中的Sn~(4+),此时ESR信号gzz>gxx>gyy。

一种新型的铅钙板栅合金——Pb-Ca-Sn-Al-Na

钠加到Pb—Ca—Sn—Al合金中,可以改善它的延伸率和浇铸性能。对于Pb—Ca—Sn—Al合金来说,钠是有效的变晶剂,它的最佳含量是0.01～0.077％。

Sn-Mo混合氧化物的缺陷结构及催化性能的研究

本文以1-丁烯在水蒸汽存在下选择性氧化制甲乙酮为典型反应,利用 XRD,ESR,IR,XPS,TEM 和 SEM 研究了 Sn-Mo 氧化物的结构与活性的关系.制备了8个样品,A,B,C,D,E,F,G 和 H 的 Mo/(Mo+Sn)分别为0,0.1,0.2,0.4,0.6,0.8,0.9,1.0.根据结构特征,可将 Sn-Mo 氧化物分为三组:第Ⅰ组 Mo/(Mo+Sn)≤0.2;第Ⅱ组0.2

The role of Sn in Pt-Sn/CeO2 catalysts for the complete oxidation of ethanol

The structural features and catalytic properties of Pt-Sn/CeO2 catalysts prepared by modified polyol method were extensively investigated for the complete oxidation of ethanol. CO chemisorption, TPR, DTA and XPS measurements identically indicated that the electronic configuration of Pt by Sn as well as the formation of PtSn alloy were the key factors in determining the nature of the active sites, A strong Pt/Sn atomic ratio dependence of catalytic perfortmances was observed. which was explained in terms of the change., in the Surface structure of metal phases and the electronic Pt-Sn interaction. (c) 2005 Elsevier B.V. All rights reserved.