Hafnium Doped Ceria Nanocomposite Oxide as a Novel Redox Additive for Three-Way Catalysts
Hafnium Doped Ceria Nanocomposite Oxide as a Novel Redox Additive for Three-Way Catalysts
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DOI：
10.1021/jp068531i
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发表时间：
2007-01
影响因子：
3.7
通讯作者：
B. M. Reddy;P. Bharali;P. Saikia;Ataullah Khan;S. Loridant;M. Muhler;W. Grünert
中科院分区：
文献类型：
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作者：
B. M. Reddy;P. Bharali;P. Saikia;Ataullah Khan;S. Loridant;M. Muhler;W. Grünert
在CexHf1 - xO2 （CH； 8:2摩尔比）和CexZr1 - xO2 （CZ； 1:1摩尔比）纳米复合氧化物上催化氧化CO，前者在较低的温度下比后者表现出更高的转化率。通过共沉淀法和在773和1073 K下煅烧获得的两种组合的热稳定性和结构稳定性，通过x射线衍射，拉曼光谱和CO-temperature程序还原技术进行了测试。XRD结果表明，CH样品在1073 K下形成了稳定的Ce0.8Hf0.2O2立方相，而CZ样品则出现了从Ce0.75Zr0.25O2到Ce0.6Zr0.4O2的相偏析。氧储存容量（OSC）和CO-TPR测量表明，由于将较小的Hf4+阳离子（离子半径0.78 a）掺入铈立方晶格中，与Zr4+ (0.84 a)相比，产生了缺陷的萤石结构，CH样品具有较高的OSC和低温还原性。Ce0.8Hf0.2O2的高活性被证明是由于…
Catalytic oxidation of CO over CexHf1 - xO2 (CH; 8:2 mole ratio) and CexZr1 - xO2 (CZ; 1:1 mole ratio) nanocomposite oxides reveals that the former combination exhibits more conversion at much lower temperature than the latter. Thermal and textural stability of both the combinations, obtained by a coprecipitation method and calcined at 773 and 1073 K, were examined by X-ray diffraction, Raman spectroscopy, and CO-temperature programmed reduction techniques. The XRD results disclose formation of a stable Ce0.8Hf0.2O2 cubic phase in the case of the CH sample, whereas CZ suffers phase segregation from Ce0.75Zr0.25O2 to Ce0.6Zr0.4O2 at 1073 K. Oxygen storage capacity (OSC) and CO-TPR measurements reveal a high OSC and low-temperature reducibility for the CH sample due to the defective fluorite structure generated upon incorporation of smaller Hf4+ cations (0.78 A ionic radius), in comparison to Zr4+ (0.84 A), into the ceria cubic lattice. The observed high activity of Ce0.8Hf0.2O2 was proven to be due to the ...