纳米Ag，CeO2和Ag-CeO2的合成及在CO催化氧化中的应用

Synthesis of Ag,CeO_2,Ag-CeO_2 Nanoparticles and Their Applications in Catalytic CO Oxidation

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.

CeO2 and Ag nanoparticles and Ag-CeO2nanocomposites were systematically prepared. The struc- tures of the catalysts and the catalytic activity for CO oxidation were studied. The results indicate that the cata- lytic 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 ~C ）. Compared with CeO2 and Ag nanoparticles, Ag-CeO2 nanocomposites showed a markedly enhanced catalytic property： CO can be com- pletely 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.