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用X-射线衍射(XRD)和X-射线光电子能谱(XPS)研究了CuO/CeO_2体系中CuO在CeO_2表面的分散状态。结果表明,CuO在CeO_2表面的分散容量约为1.20mmol/100m~2,当CuO含量低于该分散容量时Cu~(2+)在CeO_2载体表面以嵌入形式呈离子态分布;而含量高于分散容量时则有结晶态的CuO出现。首次试用静态二次离子质谱(SSIMS)研究了CuO/CeO_2样品表面第1层中Cu~(2+)/Ce~(4+)离子的比值,结果显示CuO含量为1.22和0.61mmol CuO/100m~2 CeO_2的样品中该比值分别为0.93和0.46;程序升温还原(TPR)结果表明,表面嵌入态的Cu~(2+)比晶相CuO中的Cu~(2+)更易还原而且还原分两步进行,在约153℃和165℃出现两个还原峰。用表面相互作用的嵌入模型讨论并解释了所得实验结果。
The dispersion of CuO on CeO_2 surface in CuO / CeO_2 system was investigated by X-ray diffraction (XRD) and X-ray photoelectron spectroscopy (XPS). The results show that the CuO content on the CeO_2 surface is about 1.20mmol / 100m ~ 2. When the CuO content is lower than the dispersion capacity, the Cu ~ (2+) ions are in an ionic state embedded in the CeO_2 support surface. Disperse the capacity of crystalline CuO appears. The ratio of Cu 2+ / Ce 4+ ions in the first layer on the surface of CuO / CeO 2 samples was first investigated by static secondary ion mass spectrometry (SSIMS). The results showed that CuO content was 1.22 and 0.61 mmol CuO / 100 m ~ 2 CeO_2 were 0.93 and 0.46, respectively. The results of temperature programmed reduction (TPR) showed that Cu 2+ in surface embedded state was more easily reduced and reduced than Cu 2+ in crystalline phase CuO Two steps were performed with two reduction peaks at about 153 ° C and 165 ° C. The experimental results obtained are discussed and explained with the embedded model of surface interaction.