Preparation, Characterization, and Activity of Silica Supported Metallocene Catalysts
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- 作者：Leanne Britcher ; Hanna Rahiala ; Kimmo Hakala ; Pasi Mikkola ; and Jarl B. Rosenholm
- 刊名：Chemistry of Materials
- 出版年：2004
- 出版时间：December 28, 2004
- 年：2004
- 卷：16
- 期：26
- 页码：5713 - 5720
- 全文大小：139K
- 年卷期：v.16,no.26(December 28, 2004)
- ISSN：1520-5002
文摘
Silica supported metallocene catalysts were prepared for ethylene polymerization byimmobilizing bis(cyclopentadienyl)zirconium dichloride (Cp2ZrCl2) onto both calcined silica,and silica treated with 
-aminopropyltrimethoxysilane or -mercaptopropyltrimethoxy-silane.Bis(cyclopentadienyl)zirconium chloride hydride (Cp2ZrClH) was also immobilized onto bothcalcined silica and vinyltrimethoxysilane treated silica. The catalysts were characterizedby using direct current plasma atomic emission spectroscopy (DCP-AES), diffuse reflectanceinfrared spectroscopy (DRIFT), and X-ray photoelecton spectroscopy (XPS). It was foundthat both Cp2ZrCl2 and Cp2ZrClH were adsorbed on both calcined silica and silane treatedsilica, respectively. When -aminopropyltrimethoxysilane (APTMS) was used as the spacermolecule, some of the amine became protonated upon adsorption of Cp2ZrCl2. Initial catalytictests showed that all of the complexes were catalytically active (methylaluminoxane as acocatalyst), with the Cp2ZrClH supported complexes giving the highest activities, but stilllower than the homogeneous catalyst, Cp2ZrCl2. The supported complexes produced polymerwith higher molecular weight than the homogeneous catalyst. These observations, togetherwith presented spectral evidence, support the view that the catalyst remained adsorbed inthe presence of MAO.
-aminopropyltrimethoxysilane or -mercaptopropyltrimethoxy-silane.Bis(cyclopentadienyl)zirconium chloride hydride (Cp2ZrClH) was also immobilized onto bothcalcined silica and vinyltrimethoxysilane treated silica. The catalysts were characterizedby using direct current plasma atomic emission spectroscopy (DCP-AES), diffuse reflectanceinfrared spectroscopy (DRIFT), and X-ray photoelecton spectroscopy (XPS). It was foundthat both Cp2ZrCl2 and Cp2ZrClH were adsorbed on both calcined silica and silane treatedsilica, respectively. When -aminopropyltrimethoxysilane (APTMS) was used as the spacermolecule, some of the amine became protonated upon adsorption of Cp2ZrCl2. Initial catalytictests showed that all of the complexes were catalytically active (methylaluminoxane as acocatalyst), with the Cp2ZrClH supported complexes giving the highest activities, but stilllower than the homogeneous catalyst, Cp2ZrCl2. The supported complexes produced polymerwith higher molecular weight than the homogeneous catalyst. These observations, togetherwith presented spectral evidence, support the view that the catalyst remained adsorbed inthe presence of MAO.