Navegando por Autor "Lima, S. H."

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Structural and morphological characterization of Pt/WOx–ZrO2 Catalysts
(Springer, 2008-08-09) Melo, Marcus Antônio de Freitas; Pedrosa, Anne Michelle Garrido; Melo, Dulce Maria de Araújo; Souza, M. J. B.; Araújo, Antônio S.; Lima, S. H.; Sasaki, José Marcos
Catalysts of Pt/WOx–ZrO2 type with 1 wt% of Pt and 10, 15 and 20 wt% of tungsten were synthesized and characterized. The structural and morphological features of these catalysts were studied. The samples were synthesized by impregnation method and calcined at 600 C, 700 C and 800 C. The characterizations were carried out using different techniques: X-ray diffraction, Raman spectroscopy, scanning electronic microscopy, nitrogen adsorption measurement and refinement of their crystalline structures by Rietveld method. X-ray diffraction patterns revealed the formation ZrO2 and WO3 crystalline structures and its crystallite size were determined. The zirconium oxide crystallized into tetragonal and monoclinic phases and tungsten trioxide crystallized into monoclinic phase. Crystalline WO3 and amorphous WOx species were detected by Raman spectra

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