Details

Autor(en) / Beteiligte

• Haag, Mônica Carcuchinski
• Krug, Cristiano
• Dupont, Jairton
• de Galland, Griselda Barrera
• dos Santos, João Henrique Zimnoch
• Uozumi, Toshiya
• Sano, Tsuneji
• Soga, Kazuo

Titel

Effects of Al/Zr ratio on ethylene–propylene copolymerization with supported-zirconocene catalysts

Ist Teil von

• Journal of molecular catalysis. A, Chemical, 2001-03, Vol.169 (1), p.275-287

Ort / Verlag

Amsterdam: Elsevier B.V

Erscheinungsjahr

2001

Link zum Volltext

Quelle

Elsevier Journal Backfiles on ScienceDirect (DFG Nationallizenzen)

Beschreibungen/Notizen

• Effects of heterogenization parameters on compositional and catalytic properties of Et(Ind) 2ZrCl 2 supported on silica modified with MAO were evaluated using data on metal loading, catalyst activity in ethylene–propylene copolymerization, and polymer properties. The supported catalysts were prepared according to a 2 3 factorial design for multivariate analysis. The parameters studied were: MAO concentration in impregnation, Et(Ind) 2ZrCl 2 concentration in grafting, and immobilization temperature for both metallocene and organoaluminum. The grafting solution was monitored by UV–VIS spectroscopy, while the resulting catalyst systems were characterized by inductively-coupled plasma-optical emission spectroscopy (ICP-OES), diffuse reflectance infrared Fourier transform spectroscopy (DRIFTS), and X-ray photoelectron spectroscopy (XPS). At high statistical significance, both MAO and Et(Ind) 2ZrCl 2 concentrations during preparation affected the determination of the final Al/Zr ratio on silica. The catalyst systems were tested in ethylene–propylene copolymerizations using external MAO as cocatalyst. Relationships were observed between (i) catalyst activity and the binding energy of Zr 3d 5/2 electrons and (ii) Al/Zr ratio on silica and the average ethylene incorporation. The polymer samples presented narrow molecular weight distribution, but according to differential scanning calorimetry (DSC), and cross-fractionation chromatography (CFC) data, catalyst systems with given Al/Zr ratios might yield different crystallites, suggesting a plural distribution of chemical composition.