Details

Autor(en) / Beteiligte

• Loureiro, Silvia R.
• Silveira, Fernando
• Pires, Gilvan P.
• Alves, Maria do C.
• Stedile, Fernanda C.
• dos Santos, João Henrique Z.
• Bichinho, Kátia M.
• Teranishi, Toshiharu

Titel

Analysis of supported zirconocenes by x-ray emission and absorption techniques

Ist Teil von

• X-ray spectrometry, 2005-03, Vol.34 (2), p.101-105

Ort / Verlag

Chichester, UK: John Wiley & Sons, Ltd

Erscheinungsjahr

2005

Link zum Volltext

Quelle

Wiley Online Library Journals Frontfile Complete

Beschreibungen/Notizen

• Metal contents in supported zirconocene catalysts were comparatively determined by x‐ray fluorescence spectroscopy and Rutherford backscattering spectrometry. A series of supported zirconocenes was prepared by grafting sequentially Cp2ZrCl2 (Cp = cyclopentadienyl) and (nBuCp)2ZrCl2 on to silica. The addition order and molar ratio of the two catalysts were varied. The grafted metal content was shown to be coherent between the two techniques and was between 0.37 and 0.53 wt% Zr/SiO2. The steric effect played by the ligand influences the final zirconocene grafted content. No influence of the grafting order was observed. Nevertheless, catalyst systems in which (nBuCp)2ZrCl2 was either immobilized in the first place or at a higher molar ratio were shown to be more active in ethylene polymerization. Extended x‐ray absorption fine structure analysis in the Zr‐edge showed that systems bearing Cp2ZrCl2 and (nBuCp)2ZrCl2 in a 1:3 molar ratio afforded a more disoriented system. According to electron probe microanalysis, the metal distribution in the catalyst particle was more uniform than that resulting from the immobilization of solely (nBuCp)2ZrCl2 on silica. Copyright © 2004 John Wiley & Sons, Ltd.