Influence of Alumina, Silica, and Titania Supports on the Structure and CO Oxidation Activity of CexZr1-xO2 Nanocomposit

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• 作者：Benjaram M. Reddy ; Pandian Lakshmanan ; Pankaj Bharali ; Pranjal Saikia ; Gode Thrimurthulu ; Martin Muhler ; Wolfgang Gr&uuml ; nert
• 刊名：Journal of Physical Chemistry C
• 出版年：2007
• 出版时间：July 19, 2007
• 年：2007
• 卷：111
• 期：28
• 页码：10478 - 10483
• 全文大小：356K
• 年卷期：v.111,no.28(July 19, 2007)
• ISSN：1932-7455

文摘

Nanocomposite oxides of Ce_xZr_1-xO₂ dispersed over alumina (Al₂O₃), silica (SiO₂), and titania (TiO₂) havebeen synthesized by a deposition coprecipitation method. The physicochemical characterization was carriedout by X-ray diffraction (XRD), Raman spectroscopy, high-resolution electron microscopy (HREM), andBrunauer-Emmett-Teller (BET) surface area techniques. The catalytic efficiency toward CO oxidation wasinvestigated under normal atmospheric pressure. Oxygen storage capacity (OSC) of the dispersed nano-oxideswas also evaluated and correlated with the structural characterization and CO oxidation activity results. XRDmeasurements reveal the presence of dispersed cubic Ce_0.75Zr_0.25O₂ nano-oxide phase over all the supportsand the absence of unwanted inert compounds such as Ce_9.33(SiO₄)₆O₂, ZrSiO₄, ZrTiO₄, CeAlO₃, and Ce-Tioxides. Raman spectroscopy studies suggest formation of oxygen vacancies, lattice defects, and oxygen ionsdisplacement from the ideal ceria cubic lattice positions. The HREM results indicate well-dispersed cubicCe-Zr composite oxides of the size ~5 nm over the surface of various supports. The CO oxidation activityresults and the OSC measurements reveal the same order of efficiency: that Al₂O₃-supported Ce_xZr_1-xO₂shows better performance, followed by TiO₂- and SiO₂- supported systems. The OSC properties of the supportedCe_xZr_1-xO₂ oxides show a strong influence on the CO oxidation activity.