纳米Ag,CeO2和Ag-CeO2的合成及在CO催化氧化中的应用

摘要

CeO2 and Ag nanoparticles and Ag-Ce02nanocomposites were systematically prepared. The structures of the catalysts and the catalytic activity for CO oxidation were studied. The results indicate that the catalytic activity of Ag is rather poor. The highest conversion of CO oxidation was only 40% , and smaller particles led to the worsening of the catalytic activity; for CeO2 nanoparticles, the conversion of CO oxidation could be as high as 100% , while the reaction temperature was relatively high( ca. 350 ℃ ). Compared with CeO2 and Ag nanoparticles, Ag-CeO2 nanocomposites showed a markedly enhanced catalytic property; CO can be completely oxidized to CO2 at temperature as low as 150 ℃. The excellent catalytic performance of the Ag-CeO2 nanocomposites is due to the interactions between Ag and CeO2 in nanocomposites. We discussed the relevant catalytic processes using temperature-programmed reduction (TPR) technology.%系统合成了不同粒径的CeO2和Ag纳米粒子及Ag-CeO2纳米复合粒子,并对其进行了结构表征和CO催化氧化性能测试.结果表明,Ag纳米粒子的催化活性较低,以其为催化剂时CO的最大催化转化率仅为40％,且粒径越小越容易失活；在CeO2纳米粒子催化下,CO的催化转化率可达到100％,但催化反应的温度较高(约350℃)；与CeO2和Ag相比,Ag-CeO2的催化性能明显增强,CO在较低的温度(150℃)下可实现完全转化.程序升温还原(Temperature-programmed reduction,TPR)分析结果表明,纳米复合材料中Ag和CeO2之间的相互作用是产生优异催化性能的关键原因.