Active and Stable Embedded Au@CeO2 Catalysts for Preferential Oxidation of CO

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• 作者：Matteo Cargnello ; Cristina Gentilini ; Tiziano Montini ; Emiliano Fonda ; Shareghe Mehraeen ; Miaofang Chi ; Miriam Herrera-Collado ; Nigel D. Browning ; Stefano Polizzi ; Lucia Pasquato ; Paolo Fornasiero
• 刊名：Chemistry of Materials
• 出版年：2010
• 出版时间：July 27, 2010
• 年：2010
• 卷：22
• 期：14
• 页码：4335-4345
• 全文大小：964K
• 年卷期：v.22,no.14(July 27, 2010)
• ISSN：1520-5002

文摘

We present a way to stabilize the Au phase supported on ceria by encapsulation of preformed Au nanoparticles (Au NPs) inside a porous ceria layer. The functionalization of the surface of the nanoparticles with carboxylic groups provides the link between the metal phase and the growing Ce(OH)_x barrier, which is then transformed during calcination to obtain the final Au@CeO₂ materials. The sample with a metal loading of 1 wt % shows good activity under real PReferential OXidation (PROX) conditions and better activity than catalysts of higher metal loadings or prepared through optimized deposition-precipitation methods described in the literature. Under simulated aging, the Au(1 wt %)@CeO₂ sample exhibits minor deactivation, which is mainly associated with the formation of carbonates that can be reversed by a mild regenerative oxidative treatment to fully restore its initial activity. Vice versa, the other catalysts show either the unavoidable reversible carbonate poisoning or the irreversible deactivation due to metal sintering/agglomeration phenomena. A plethora of characterization techniques (CO chemisorption, X-ray diffraction, X-ray absorption spectroscopy, aberration-corrected scanning transmission electron microscopy) has been used to confirm the structure of these catalysts and to identify the underlying phenomena controlling their activity.