Supported Zr-and Hf-cene Catalysts for Propylene Polymerization |
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Authors: | L. A. Novokshonova T. M. Ushakova M. V. Lysova O. I. Kudinova V. G. Krasheninnikov A. L. Lyubimtsev |
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Affiliation: | 1. Semenov Institute of Chemical Physics, RAS, Kosygin St., 4, 119991 Moscow, Russia;2. Moscow State University, Leninskie Gory, 1, 119992 Moscow, Russia |
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Abstract: | The supported metallocene catalysts were obtained on the layered silicate montmorillonite (MMT), using AlMe3 and AliBu3 for synthesis of alkylaluminoxane directly on a support surface, followed by metallocene supporting. It was shown that the MMT-H2O/AliBu3 forms with ansa-Zr-cenes of C1 and C2-symmetry the significantly more active supported metal-alkyl complexes in propene polymerization, than MMT-H2O/AlMe3. The MMT-H2O/AliBu3 is the effective activator of the ansa-Hf-cenes, in contrast to MAO and MMT-H2O/AlMe3, giving the high active supported catalysts for synthesis of isotactic and elastic polypropene. The character of influence of metallocene fixation on support on the isotactic pentad [mmmm] content in polymer, compared to homogeneous analogues, depends on the metallocene nature. The introduction of borate Ph3CB(C6F5)4 in the case of both Zr-cene and Hf-cene catalysts increases significantly the activity at the reduced ratio of Al/Zr, Hf (100–500 instead of 2000–3000) and stabilizes the catalytic complexes. |
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Keywords: | metallocene catalyst polymerization polypropylene (PP) |
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