Structural, microstructural and surface properties of a specific CeO{sub 2}-Bi{sub 2}O{sub 3} multiphase system obtained at 600 {sup o}C

Journal Article · Tue Mar 15 00:00:00 EDT 2011 · Journal of Solid State Chemistry

DOI:https://doi.org/10.1016/j.jssc.2011.01.022· OSTI ID:21494236

Bourja, Lamia; Bakiz, Bahcine ^[1]; Benlhachemi, Abdeljalil; Ezahri, Mohamed ^[2]; Villain, Sylvie ^[1]; Crosnier, Olivier ^[3]; Favotto, Claude ^[1]; Gavarri, Jean-Raymond ^[1]

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1. Institut Materiaux Microelectronique et Nanosciences de Provence, IM2NP, UMR CNRS 6242, Universite du Sud Toulon-Var, BP 20132, 83957 La Garde Cedex (France)
2. Laboratoire Materiaux et Environnement LME, Faculte des Sciences, Universite Ibn Zohr, BP 8106, Cite Dakhla, Agadir, Maroc (Morocco)
3. Laboratoire de Genie des Materiaux et Procedes Associes, Polytech Nantes, rue Christian Pauc BP 50609, 44306 Nantes Cedex 3 (France)

Polycrystalline samples of (1-x) CeO{sub 2}-x/2 Bi{sub 2}O{sub 3} phases, where x is the atom fraction of bismuth have been synthesized by the precipitation process and after the thermal treatment at 600 {sup o}C, under air. Samples are first characterized by the X-ray diffraction and scanning electron microscopy. To determine the samples specific surface areas, Brunauer-Emmett-Teller (BET) analyses have been performed. In the composition range 0{<=}x{<=}0.20, a cubic solid solution with fluorite structure is obtained. For compositions x comprised between 0.30 and 0.90, two types of T' (or {beta}') and T (or {beta}) tetragonal phases, similar to the well-known {beta}' or {beta} Bi{sub 2}O{sub 3} metastable structural varieties, are observed. However, the crystal cell volumes of these {beta}' or {beta} Bi{sub 2}O{sub 3} phases increase with the composition x in bismuth: this might be due to the presence of defects or substitution by cerium atoms, in the tetragonal lattices. Using X-ray diffraction profile analyses, correlations between bismuth composition x and crystal sizes or lattice distortions have been established. The solid-gas interactions between these polycrystalline materials and air-CH{sub 4} and air-CO flows have been studied as a function of temperature and composition x, using Fourier transform infrared (FTIR) analyses of the conversions of CH{sub 4} and CO gases into the CO{sub 2} gas. The transformations of CH{sub 4} and CO molecules as a function of time and temperature are determined through the intensities of FTIR CO{sub 2} absorption bands. Using the specific surface areas determined from BET analyses, these FTIR intensities have been normalized and compared. For all bismuth compositions, a low catalytic reactivity is observed with air-CH{sub 4} gas flows, while, for the highest bismuth compositions, a high catalytic reactivity is observed with air-CO gas flows. -- Graphical abstract: Catalytic efficiencies of CeO{sub 2}-Bi{sub 2}O{sub 3}system: catalytic actions on methane (on the left) or carbon monoxide (on the right) of (1-x)CeO{sub 2}-x/2 Bi{sub 2}O{sub 3} samples, as a function of the fraction x, and for fixed temperatures: on the vertical axis, the intensities of CO{sub 2} FTIR absorption bands are reported. Strong efficiency of bismuth rich samples for CO conversion. Display Omitted Research highlights: {yields} Stabilization of metastable polymorph Bi{sub 2}O{sub 3} phases in the mix system [(1-x)CeO{sub 2}+(x/2)Bi{sub 2}O{sub 3}] at 600 {sup o}C. {yields} Solid gas interactions between this system and air-CO or air-CH{sub 4} gas flows at various temperatures and bismuth compositions. {yields} High efficiency of bismuth rich samples to convert CO into CO{sub 2}.

• OSTI ID: 21494236
• Journal Information: Journal of Solid State Chemistry, Vol. 184, Issue 3; Other Information: DOI: 10.1016/j.jssc.2011.01.022; PII: S0022-4596(11)00023-5; Copyright (c) 2011 Elsevier Science B.V., Amsterdam, The Netherlands, All rights reserved.; ISSN 0022-4596
• Country of Publication: United States
• Language: English

Related Subjects

36 MATERIALS SCIENCE
37 INORGANIC
ORGANIC
PHYSICAL AND ANALYTICAL CHEMISTRY
ABSORPTION
BISMUTH OXIDES
CARBON DIOXIDE
CARBON MONOXIDE
CERIUM OXIDES
EFFICIENCY
FLUORITE
GAS FLOW
HEAT TREATMENTS
INFRARED SPECTRA
METHANE
POLYCRYSTALS
SCANNING ELECTRON MICROSCOPY
SOLID SOLUTIONS
SPECIFIC SURFACE AREA
SURFACE PROPERTIES
TEMPERATURE DEPENDENCE
TEMPERATURE RANGE 0400-1000 K
TETRAGONAL LATTICES
X-RAY DIFFRACTION
ALKANES
BISMUTH COMPOUNDS
CARBON COMPOUNDS
CARBON OXIDES
CERIUM COMPOUNDS
CHALCOGENIDES
COHERENT SCATTERING
CRYSTAL LATTICES
CRYSTAL STRUCTURE
CRYSTALS
DIFFRACTION
DISPERSIONS
ELECTRON MICROSCOPY
FLUID FLOW
HALIDE MINERALS
HOMOGENEOUS MIXTURES
HYDROCARBONS
MICROSCOPY
MINERALS
MIXTURES
ORGANIC COMPOUNDS
OXIDES
OXYGEN COMPOUNDS
PHYSICAL PROPERTIES
RARE EARTH COMPOUNDS
SCATTERING
SOLUTIONS
SORPTION
SPECTRA
TEMPERATURE RANGE