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Title: Microporous and mesoporous supports and their effect on the performance of supported metallocene catalysts
Authors: Silveira, Fernando Tobias
Alves, Maria do Carmo Martins
Stedile, Fernanda Chiarello
Pergher, Sibele Berenice Castellã
Santos, João Henrique Zimnoch dos
Keywords: Supported metallocene;Polyethylene;Microporous supports;Mesoporous supports;EXAFS
Issue Date: 15-Jan-2010
Publisher: Elsevier
Citation: SILVEIRA, Fernando; ALVES, Maria do Carmo Martins; STEDILE, Fernanda C.; PERGHER, Sibele B. C.; SANTOS, João Henrique Zimnoch dos. Microporous and mesoporous supports and their effect on the performance of supported metallocene catalysts. Journal Of Molecular Catalysis A: Chemical, [s. l.], v. 315, n. 2, p. 213-220, 15 jan. 2010. ISSN 1381-1169, DOI Disponível em: Acesso em: 28 maio 2020.
Portuguese Abstract: A series of hybrid-supported catalysts was prepared by sequentially grafting Cp2ZrCl2 and (nBuCp)2ZrCl2 (1:3 ratio) onto synthesized silica–zirconia xerogel, alumino-silicates, alumina, chrysotile and commercial MAO (methylaluminoxane)-modified silica. Supported catalysts were characterized by Rutherford backscattering spectrometry, atomic force microscopy, extended X-ray absorption fine structure spectroscopy, X-ray diffraction and nitrogen adsorption. The grafted metal content was between 0.21 and 1.00 wt.% Zr/SiO2 or Zr/Al2O3. All of the systems were shown to be active in ethylene polymerization with methylaluminoxane as the cocatalyst. The catalyst activity and polymer molecular weight depended on the effects of the textural characteristics of the supports on the structure of the generated supported catalyst species. The highest activity in ethylene polymerization (ca. 6560 kgPE molZr−1 h−1) was reached with the supported catalyst using commercial MAO-modified silica and also presented the lowest surface roughness. Correlation between EXAFS data and polymer characteristics was extracted: the production of polyethylenes with higher molecular weight was associated with the reduction in the interatomic Zr–O distance of the supported catalysts, which was shown to be dependent on the nature of the support.
ISSN: 1381-1169
Appears in Collections:IQ - Artigos publicados em periódicos

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