Resumo

HERNANDEZ ENRIQUEZ, J. M. et al. Síntesis, caracterización y evaluación catalítica de un ZrO₂ con fase monoclínica. Superf. vacío [online]. 2009, vol.22, n.2, pp.1-9. ISSN 1665-3521.

The present work deals with the synthesis of zirconium oxides (ZrO₂) by the sol-gel method varying the calcination temperature (100, 200, 400, 500, 600 y 800°C) and studying the possible influence of this parameter or synthesis variable on the textual, structural and acid properties of ZrO₂. Materials were analyzed by nitrogen physisorption, X-ray diffraction, thermal analysis, infrared spectroscopy, NH₃ temperature-programmed desorption and 2-propanol dehydration. The catalytic activity of monoclinic zirconia calcined at temperature of 600°C was evaluated in the isomerization of n-hexane at 250°C and atmospheric pressure. It was observed that the calcination temperature had a great influence over the textural properties, crystallinity degree and acidity of the materials. The synthesized supports were classified as mesoporous materials, nanocrystalline with an acceptable acid degree up to 600°C. Although it is considered that the tetragonal phase of zirconium oxide as a synonym of catalytic activity, in this work it is shown that a monoclinic zirconia can be a potential solid acid catalyst, taking part in alcohol dehydration and selective isomerization of n-hexane.

Palavras-chave : Zirconium oxides; Sol-gel; Calcination; Physicochemical properties.

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