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Please use this identifier to cite or link to this item: http://repositorio.ufba.br/ri/handle/ri/8499

Title: Effect of chromium on magnetite formation
Other Titles: Catalysis Letters
Authors: Varela, Maria do Carmo Rangel Santos
Sassaki, Renato Massami
Galembeck, Fernando
Keywords: magnetite formation;chromium-doped magnetite;HTS catalyst;iron(III)hydroxoacetate
Issue Date: 1995
Abstract: Chromium-doped magnetite is the traditional catalyst used in the high temperature shift reaction in industrial processes. This work reports a method for preparing this solid, by heating chromium-doped iron(III)hydroxoacetates (IHA), prepared both by coprecipitation and by impregnation. This method provides the production of the catalyst in its active form avoiding the step of activation in industrial processes. It was noted that the presence of chromium affects magnetite formation as well as its characteristics. IHA containing chromium produces magnetite at higher temperature than does the pure IHA. Chromium-doped magnetites have higher surface areas, are less crystalline, have lower Fe(II)/Fe(III) ratios and are catalysts more active than those obtained from plain IHA. These effects depend on the preparation method of the precursor. It was also found that the impregnated sample is made of aggregates of a few crystals whereas the coprecipitate is made of smaller polycrystalline particles. In addition, the coprecipitation method leads to a more even distribution of chromium in solids. These observations are consistent with the best performance shown by the catalyst prepared by coprecipitation.
Description: Texto completo: acesso restrito. p.237-254
URI: http://www.repositorio.ufba.br/ri/handle/ri/8499
ISSN: 1011-372X
Appears in Collections:Artigos Publicados em Periódicos (Quimica)

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