Preparation and CO conversion activity of ceria nanotubes by carbon nanotubes templating method
来源期刊：JOURNAL OF RARE EARTHS2008年第2期
论文作者：SHI Liyi ZHANG Dengsong CAO Zhiyuan FANG Jianhui SHEN Xia DING Weizhong
Key words：ceria nanotube; CO oxidation; carbon nanotube; templating method; rare earths;
Abstract: 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 CeO2/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.
SHI Liyi1，ZHANG Dengsong1，CAO Zhiyuan2，FANG Jianhui2，SHEN Xia2，DING Weizhong3
(1.Research Center of Nanoscience and Technology, Shanghai University, Shanghai 200444, China;
2.Department of Chemistry, School of Science, Shanghai University, Shanghai 200444, China;
3.Department of Materials and Engineering, School of Material Science and Engineering, Shanghai University, Shanghai 200072, China)
Abstract: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 CeO2/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.
Key words:ceria nanotube; CO oxidation; carbon nanotube; templating method; rare earths;
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