Navegando por Palavras-chave "Polymeric precursors"

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    CeO2-catalyzed ozonation of phenol
    (Springer, 2010-12-01) Pinheiro da Silva, M. F.; Soeira, L. S.; Daghastanli, K. R. P.; Martins, T. S. [UNIFESP]; Cuccovia, I. M.; Freire, R. S.; Isolani, P. C.; Universidade de São Paulo (USP); Universidade Federal de São Paulo (UNIFESP)
    Three different cerium citrate-based precursors were used for synthesizing CeO2 through thermal treatment. Three morphological types of CeO2 were obtained. Characterization of these oxides was carried out by XRD patterns, SEM microscopy, N-2 adsorption isotherms, Raman spectroscopy, zeta potential, and UV/Vis luminescence. Ozonation of phenol catalyzed by CeO2 was studied as a representative reaction of environmental interest. the differences on the catalytic activity showed by these three oxides could be correlated to amounts of Ce3+ on CeO2 surface and, consequently, to the demand for oxygen needed to burn each precursor.
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    The role of citrate precursors on the morphology of lanthanide oxides obtained by thermal decomposition
    (Springer, 2010-02-01) Pinheiro da Silva, Mauro Francisco; Souza Carvalho, Flavio Machado de; Martins, Tereza da Silva [UNIFESP]; Abreu Fantini, Marcia Carvalho de; Isolani, Paulo Celso; Universidade de São Paulo (USP); Universidade Federal de São Paulo (UNIFESP)
    Two series of lanthanide oxides with different morphologies were synthesized through calcinations of two types of citrate polymeric precursors. These oxides were characterized by XRD patterns, SEM electronic microscopy, and N(2) adsorption isotherms. SEM microscopy analysis showed that the calcination of crystalline fibrous precursors [Ln(2)(LH)(3)center dot 2H(2)O] (L = citrate) originated fibrous shaped particles. On the other hand, the calcination of irregular shaped particles of precursors [LnL center dot xH(2)O] originated irregular shaped particles of oxide, pointing out a morphological template effect of precursors on the formation of the respective oxides.