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

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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.

Keywords: Gold catalysts, WGS, Ceria doped by Yb, Sm, Gd, Y, La, XRD, HRTEM, Raman, XPS, TPR

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Informasi Detail

Judul Seri

Applied Catalysis A: General

No. Panggil

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Penerbit

London : Elsevier B.V.., 2009

Deskripsi Fisik

Applied Catalysis A: General 357 (2009) 159–169

Bahasa

English

ISBN/ISSN

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Klasifikasi

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Tipe Isi

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Tipe Media

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Tipe Pembawa

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Edisi

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Subjek

KIMIA

Info Detail Spesifik

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Pernyataan Tanggungjawab

agus

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