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Heterogeneous metallocene catalysts for ethylene polymerization |
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| Institution: | 1. Sinopec Shanghai Research Institute of Petrochemical Technology CO.,LTD., Division of Synthetic Polymers, Pudong New Area of Pudong North Road No. 1658, Shanghai, China;2. Maastricht University, Faculty of Science and Engineering, Department of Biobased Materials, Brightlands Chemelot Campus, Geleen 6167 RD, the Netherlands;3. King Abdullah University of Science and Technology (KAUST), Division of Physical Science and Engineering, Chemistry, Thuwal, 23955-6900 Kingdom of Saudi Arabia;1. Symbiosis Institute of Technology (SIT), Symbiosis International (Deemed University) (SIU), Lavale, Pune, India;2. Symbiosis Centre for Research and Innovation (SCRI), Symbiosis International (Deemed University) (SIU), Lavale, Pune, India |
| Abstract: | The catalyst precursor 9-fluorenylidene-1-cyclopentadienylidene-2-hex-5-enylidene zirconium dichloride proved to be highly active in the heterogeneously catalyzed polymerization of ethylene using silica gel/partially hydrolyzed trimethylaluminum (PHT) as cocatalyst. The substitution of position 4 of the fluorenylidene fragment and position 3 of the cyclopentadienylidene ring improves the catalyst activity. The introduction of a phenyl group into the bridge increases the catalyst activity and the molecular weight of the polymer. The prepolymerization of this catalyst system leads to a major change in catalyst and polymer properties. A significant increase in catalyst activity and a lower molecular weight of the produced polyethylene is observed. The presence of hydrogen during prepolymerization or polymerization of ethylene produces a broader molecular weight distribution indicating a higher number of different active centers. |
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