Preparation and CO conversion activity of ceria nanotubes by carbon nanotubes templating method

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• 作者：Jianhui FANG ; Zhiyuan CAO ; Dengsong ZHANG ; Xia SHEN ; Weizhong DING ; Liyi SHI
• 关键词：ceria nanotube ; CO oxidation ; carbon nanotube ; templating method ; rare earths
• 刊名：Journal of Rare Earths
• 出版年：2008
• 出版时间：April 2008
• 年：2008
• 卷：26
• 期：2
• 页码：153-157
• 全文大小：2083 K

文摘

Ceria nanotubes with high CO conversion activity by means of carbon nanotubes as removable templates in the simple liquid phase process were fabricated under moderate conditions. The pristine CNTs were first pretreated by refluxing in a 30 % nitric acid solution at 140 °C for 24 h, then dispersed in an ethanolic Ce(NO₃)₃·6H₂O solution with ultrasonic radiation at room temperature for 1 h. Under vigorous stirring, NaOH solution was added drop by drop into the above ethanolic solution until the pH value was 10. The product was collected and repeatedly washed with ethanol and on drying at 60 °C, the CeO_2/CNT composites were obtained. Then, the as-prepared composites were heated at 450 °C in an air atmosphere for 30 min to remove CNTs. The ceria nanotubes were characterized by X-Ray Diffraction (XRD), Transmission Electron Microscopy (TEM), and X-Ray Photoelectron Spectrum (XPS). The results showed that the ceria nanotubes were polycrystalline face-centered cubic phase and were composed of lots of dense ceria nanoparticles. The diameter of ceria nanotubes was about 40–50 nm. Catalytic activity of the product for CO oxidation was carried out at the region of 30–300 °C in a U-shaped quartz reactor with feeding about 0.15 g of the catalyst, which was loaded on Al₂O₃ carrier. The inlet gas composition was 1.0 % CO and 28 % O₂ with N₂ as balance, and the rate of flow was kept at 40 ml/min. The catalytic products were analyzed by gas chromatography. The as-prepared CeO₂ nanotubes showed higher CO oxidation activity, which indicated that the morphology of ceria products affected the catalytic performance. The ceria nanotubes supported on Al₂O₃ demonstrated that conversion temperature for CO oxidation to CO₂ was lower than that for bulk catalysts.