Hybrid zirconocene supported catalysts

详细信息    查看全文

• 作者：Silveira ; Fernando ; Loureiro ; Silvia R. ; de Galland ; Griselda B. ; Stedile ; Fernanda C. ; dos Santos ; Joã ; o Henrique Z. ; et. al.
• 关键词：Supported metallocenes ; Hybrid catalysts ; Ethylene polymerization ; Silica ; RBS
• 刊名：Journal of Molecular Catalysis A: Chemical
• 出版年：2003
• 出版时间：October 1, 2003
• 年：2003
• 卷：206
• 期：1-2
• 页码：389-398
• 全文大小：175 K

文摘

A series of supported catalysts were prepared by combining (nBuCp)b>2b>ZrClb>2b> and Cpb>2b>ZrClb>2b> sequentially grafted on silica in different ratio (1:1 and 1:3) and immobilization order. Catalyst systems were characterized by Rutherford backscattering spectrometry (RBS), diffuse reflectance infrared Fourier transform spectroscopy (DRIFTS), scanning electron microscopy (SEM) and electron probe microanalysis (EPMA). Grafted metal content remained comprised between 0.37 and 0.53wt. % Zr/SiOb>2b>. All the systems were shown to be active in ethylene homopolymerization having methylaluminoxane as co-catalyst. Catalyst activity was shown to be dependent on the metallocene nature, but not on the addition order or molar ratio. The highest activity was achieved with Cpb>2b>ZrClb>2b>/(nBuCp)b>2b>ZrClb>2b> (1:3) catalyst system (ca. 4.26kg PE (mmol Zrh)⁻¹). Resulting polymers were characterized by GPC and DSC. In spite of bearing two catalyst centers, no bimodality was observed in the resulting polymers.