Active Gold-Ceria and Gold-Ceria/titania Catalysts for CO Oxidation. From Single-Crystal Model Catalysts to Powder Catalysts

Journal Article · Wed Jul 23 00:00:00 EDT 2014 · Catalysis Today

DOI:https://doi.org/10.1016/j.cattod.2014.06.033· OSTI ID:1228903

Rodriguez, Jose A. ^[1]; Si, Rui ^[1]; Evans, Jaime ^[2]; Xu, Wenqian ^[1]; Hanson, Jonathan C. ^[1]; Tao, Jing ^[1]; Zhu, Yimei ^[1]

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1. Brookhaven National Lab. (BNL), Upton, NY (United States)
2. Central Univ. of Venezuela, Caracas (Venezuela)

We studied CO oxidation on model and powder catalysts of Au-CeO₂ and Au-CeO_x/TiO₂. Phenomena observed in Au-CeO₂(1 1 1) and Au-CeO₂/TiO₂(1 1 0) provided useful concepts for designing and preparing highly active and stable Au-CeO_x/TiO₂ powder catalysts for CO oxidation. Small particles of Au dispersed on CeO₂(1 1 1) displayed high catalytic activity, making Au-CeO₂(1 1 1) a better CO oxidation catalyst than Au-TiO₂(1 1 0) or Au-MgO(1 0 0). An excellent support for gold was found after depositing nanoparticles of ceria on TiO₂(1 1 0). The CeO_x nanoparticles act as nucleation centers for gold, improving dispersion of the supported metal and helping in the creation of reaction sites efficient for the adsorption of CO and the dissociation of the O₂ molecule. High-surface area catalysts were prepared by depositing gold on ceria nanorods and CeO_x/TiO₂ powders. The samples were tested for the low-temperature (10–70 °C) oxygen-rich (1%CO/4%O₂/He) CO oxidation reaction after pre-oxidation (20%O₂/He, 300 °C) and pre-reduction (5%H₂/He, 300 °C) treatments. Moreover, synchrotron-based operando X-ray diffraction (XRD) and X-ray absorption (XAS) spectroscopy were used to study the Au-CeO₂ and Au-CeOx/TiO₂ catalysts under reaction conditions. Our operando findings indicate that the most active phase of these catalysts for low-temperature CO oxidation consist of small particles of metallic Au dispersed on CeO₂ or CeO_x/TiO₂.

• Research Organization: Brookhaven National Lab. (BNL), Upton, NY (United States)
• Sponsoring Organization: USDOE Office of Science (SC), Basic Energy Sciences (BES)
• DOE Contract Number: SC00112704
• OSTI ID: 1228903
• Report Number(s): BNL-110978-2015-JA
• Journal Information: Catalysis Today, Vol. 240; ISSN 0920-5861
• Publisher: Elsevier
• Country of Publication: United States
• Language: English

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