CuO-BaO/SiO2催化剂的结构表征

以XRD、XPS和EXAFS手段对CuO－BaO／Sic2催化剂及其还原态的结构进行了研究．结果表明，在CuO－BaO／SiO2体系中铜和钡都是以氧化态的形式存在，超细SiO2载体对所负载的CuO的结构有影响．随着样品负载量的逐渐降低，Cu－O和Cu－Cu睡的健长和配位数逐渐征小，而且低载量样品的健长和配位数减小的幅度最大．在总负载量＞13．39％的样品中，CuO以晶相的形式存在；总负载量＜13．39％的样品中，CUO呈现单层分布的高分出状态．还原态样品中钢以本价铜的形式存在，随负载量的降低，还原态Cu－Cu健的镇长和配位数也分别呈现出逐渐减小的趋势．还原态中心铜原子在催化剂表面的分布状态基本上保持了氧化态催化剂中CuO物相的分市状态．

Characterization of CuO-BaO/SiO_2 Catalysts Structure

The structure of CuO-BaO/SiO2 catalysts and their reduced states has been char-act,erized by means of XRD, XPS and EXAFS. Both the results of XRD and XPS indicate that(topper and barium in CuO-BaO/SiO2 exist in CuO and BaO respectively and the SiO2 supporthas influence on the structure of CuO. The EXAFS results show that the coordination nunther andlength of Cu-O shell and Cu-Cu shell gradually decrease with the supported content decreasingand the extent of decrease is the largest for low supported content samples. When the supportedcontent exceeds 13.39%, CuO in samples is in crystalline state, when the supported content issmaller or equals 13.39%, CuO in samples is in monolayer dispersion state. In the reduced catalystsamples, only metal copper is detected. With the content of CuO in CuO-BaO/SiO2 decreasing,the length and coordination number of Cu-Cu bond of metal copper on reduced catalyst surfacealso decrease gradually.