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Reducibility study of the LaMxFe1−xO3 (M = Ni, Co) perovskites

Published online by Cambridge University Press:  18 March 2011

C. Estournès
Affiliation:
IPCMS Groupe des Matériaux Inorganiques, UMR7504 CNRS-ULP-ECPM, 23 rue du Loess 67037 Strasbourg Cedex, France
H. Provendier
Affiliation:
Laboratoire de la Réactivité Catalytique, des Surfaces et Interfaces, UMR 7515, ECPM- CNRS-ULP, 25 rue Becquerel, 67087 Strasbourg Cedex 2, France
L. Bedel
Affiliation:
Laboratoire de la Réactivité Catalytique, des Surfaces et Interfaces, UMR 7515, ECPM- CNRS-ULP, 25 rue Becquerel, 67087 Strasbourg Cedex 2, France
C. Petit
Affiliation:
Laboratoire de la Réactivité Catalytique, des Surfaces et Interfaces, UMR 7515, ECPM- CNRS-ULP, 25 rue Becquerel, 67087 Strasbourg Cedex 2, France
A.C. Roger
Affiliation:
Laboratoire de la Réactivité Catalytique, des Surfaces et Interfaces, UMR 7515, ECPM- CNRS-ULP, 25 rue Becquerel, 67087 Strasbourg Cedex 2, France
A. Kiennemann
Affiliation:
Laboratoire de la Réactivité Catalytique, des Surfaces et Interfaces, UMR 7515, ECPM- CNRS-ULP, 25 rue Becquerel, 67087 Strasbourg Cedex 2, France
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Abstract

Solid solutions of LaMxFe1−xO3 (with M = Ni and Co) have been used in the Fischer- Tropsch reaction (CO + H2 → Hydrocarbons + CO2) and in the partial oxidation of methane (CH4 + 1/2 O2 → CO + 2 H2). In both catalytic reactions, the active catalyst is reported to be reduced metal particles; their size and their interactions with the support induce large differences in the product distribution.

In the nickel system, after total reduction by TPR all catalysts exhibit ferromagnetic behavior at room temperature. In situ magnetization in 1 Tesla on cooling the sample under reducing atmosphere shows one magnetic transition for each sample indicating one Curie temperature. These Curie temperatures are in between those known for bulk nickel and iron and decrease with the initial nickel content of the perovskite. This indicates that nickel is reduced first and induces the reduction of iron, leading to the formation of an alloy.

In the cobalt system, in situ magnetization on heating the sample shows a sharp increase of the magnetization only for x = 0.25, 0.40 and 1, corresponding to the formation of metallic cobalt nanoparticles. All other materials present only one increase of the magnetization for temperatures similar to those observed for the second reduction in TPR corresponding to the formation of CoFe alloys.

Type
Research Article
Copyright
Copyright © Materials Research Society 2001

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