Gold catalysts supported on ceria doped by rare earth metals for water gas shift reaction: influence of the preparation method

Date
2009
Authors
Andreeva, D.
Ivanov, I.
Ilieva, L.
Abrashev, M. V.
Zanella, R.
Sobczak, J. W.
Lisowski, W.
Kantcheva, M.
Avdeev, G.
Petrov, K.
Advisor
Supervisor
Co-Advisor
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Instructor
Source Title
Applied Catalysis A: General
Print ISSN
0926-860X
Electronic ISSN
1873-3875
Publisher
Volume
357
Issue
2
Pages
159 - 169
Language
English
Type
Article
Journal Title
Journal ISSN
Volume Title
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Abstract

Gold catalysts based on ceria, doped by various RE metals (La, Sm, Gd, Yb, Y) were studied. The influence of the preparation methods on structure, properties and catalytic activity in the WGS reaction was investigated. The catalysts' supports were prepared using two different methods: co-precipitation (CP) and mechanochemical activation (MA). The catalysts were tested in a wide temperature interval without and after reactivation. All samples were characterized using a combination of X-ray diffraction (XRD), high resolution transmission electron microscopy (HRTEM), Raman spectroscopy (RS) and X-ray photoelectron spectroscopy (XPS) and TPR. It was found that the catalytic activity of MA catalysts is higher than CP ones. The gold catalysts based on ceria doped by Yb and Sm exhibited the highest activity. After reactivation in air the MA samples almost kept the WGS activity same, while the CP catalysts increased it. The catalysts of a single- and double-phase structure are formed as a result of CP and MA preparation, respectively. There are no big differences in the gold particles size (2-3 nm) depending on dopants and on the preparation techniques. The RS spectra analysis indicates that most probably the oxygen vacancies are adjacent to Me3+ dopant and the ceria structure seems to be better ordered than in the case of alumina as a dopant. There is no distinct correlation between reducibility and WGS activity. The XPS analysis disclose positively charged gold particles in addition to metallic gold within a surface region of fresh samples and only metallic gold on the samples after catalytic processing. There is no simple correlation between the concentration of Ce3+ in the samples and their WGS activity.

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Keywords
Ceria doped by Yb, Sm, Gd, Y, La, HRTEM, TPR, WGS, XPS, XRD, Catalysis, Catalyst activity, Cerium, Cerium compounds, Chemical shift, Doping (additives), Electrochemical sensors, Gadolinium, Gold, High resolution transmission electron microscopy, Inert gases, Lanthanum, Nonferrous metals, Oxygen, Oxygen vacancies, Rapid solidification, Spectrum analysis, X ray diffraction analysis, X ray photoelectron spectroscopy, Ytterbium, Yttrium alloys, Gold catalysts, Raman, Catalyst supports
Citation
Published Version (Please cite this version)