Details

Autor(en) / Beteiligte

• dos Santos, João Henrique Zimnoch
• Dorneles, Silvio
• Stedile, Fernanda Chiarello
• Dupont, Jairton
• de Camargo Forte, Maria Madalena
• Baumvol, Israel Jacob Rabin

Titel

Silica supported zirconocenes and Al-based cocatalysts: surface metal loading and catalytic activity

Ist Teil von

• Macromolecular chemistry and physics, 1997-11, Vol.198 (11), p.3529-3537

Ort / Verlag

Zug: Hüthig & Wepf Verlag

Erscheinungsjahr

1997

Link zum Volltext

Quelle

Wiley Online Library Journals Frontfile Complete

Beschreibungen/Notizen

• The Zr surface loading from Cp2ZrCl2 toluene solutions on different kinds of commercial silicas (Grace 948, 952 and 956) was determined by Rutherford backscattering spectrometry. In all silicas, a saturation trend was observed with increasing amount of metal in the initial solution, the largest Zr loading value (1 wt.‐%) being observed for silica Grace 948. Solid surface areas were determined by the BET method before and after metallocene immobilization, revealing that the values do not change after zirconocene impregnation. Two different kinds of cocatalyst were used, methylaluminoxane and trimethylaluminium. The aluminium loading on silica Grace 948 was determined using the 27Al(p,γ)28Si nuclear reaction and titrometry, both showing that methylaluminoxane leads to an “Al grafting” four times more efficient than does trimethylaluminium. Finally, the catalytic activity of these systems was tested in the polymerization of ethylene. The supported catalysts were shown to be active, specially using the low cost trimethylaluminium as a cocatalyst. The polymers obtained with the supported systems exhibited a higher molecular weight than those obtained with the homogeneous system.