Effects of Spatial Distributions of Active Sites in a Silica-Supported Metallocene Catalyst on Particle Fragmentation and Reaction in Gas-Phase Ethylene Polymerization
This work presents the experimental investigation of the effects of intraparticle catalyst site distribution on the catalyst particle fragmentation in gas-phase ethylene polymerization over a silica-supported metallocene catalyst (rac-dimethylsilylbis(2-methyl-4-phenylindenyl)-dimethyl zirconium) w...
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Veröffentlicht in: | Macromolecules 2022-04, Vol.55 (7), p.2444-2455 |
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Hauptverfasser: | , , |
Format: | Artikel |
Sprache: | eng |
Online-Zugang: | Volltext |
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Zusammenfassung: | This work presents the experimental investigation of the effects of intraparticle catalyst site distribution on the catalyst particle fragmentation in gas-phase ethylene polymerization over a silica-supported metallocene catalyst (rac-dimethylsilylbis(2-methyl-4-phenylindenyl)-dimethyl zirconium) with methylaluminoxane (MAO) as a cocatalyst. The supported catalysts with different spatial distributions of Al and Zr were prepared by varying the catalyst immobilization conditions, and the catalyst metal distributions were analyzed using the focused ion beam (FIB) and scanning electron microscopy–energy-dispersive spectroscopy (SEM–EDX) techniques. The experimental data showed that impregnation time and catalyst solution concentration had strong effects on the radial distributions of Zr in silica particles and fines formation during the gas-phase polymerization of ethylene. The supported catalyst with a high Zr concentration near the exterior region of a catalyst particle generated more fines than a supported catalyst with uniformly distributed Zr during the gas-phase polymerization, suggesting that the optimal distribution of catalyst sites needs to be considered in designing the silica-supported catalyst for improved control of polymer particle morphology. |
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ISSN: | 0024-9297 1520-5835 |
DOI: | 10.1021/acs.macromol.1c02551 |