| Modification of the(SiO_2/MgO/MgCl_2)·TiCl_x Ziegler-Natta Polyethylene Catalysts Using the Third Metal Elements |
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| 基金项目： | This work was financially supported by the National Natural Science Foundation of China，the Major State Basic Research Development Program of China，the Fundamental Research Funds for the Central Universities and Research Program of Introducing Talents of Discipline of University |
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| 摘 要： | Various(SiO_2/MgO/MgCl_2)·Ti Clx Ziegler-Natta catalysts modified by the third metal elements were synthesized by the co-impregnation of water-soluble magnesium and the third metal salts. Several key factors including the electronegativity of the third metal elements, catalyst performances in ethylene homo-polymerization, ethylene/1-hexene copolymerization and hydrogen response were systematically investigated. Both the catalyst performance and the polymer properties are influenced by the introduction of the third metal elements. Compared with the unmodified(SiO_2/MgO/MgCl_2)·Ti Clx Ziegler-Natta catalyst, activity and 1-hexene incorporation are enhanced by the introduction of zirconium, vanadium, aluminum and chromium, while deteriorated by the addition of ferrum, nickel, molybdenum and tungsten. Correlations of the catalyst activities and 1-hexene incorporation ability with the electronegativity of the third metal elements are discovered. It is found that the lower electronegativity of the third metal elements leads to the catalyst with higher activity and higher α-olefin co-polymerization ability. The polyethylene produced by a nickel modified catalyst showed broad molecular weight distribution(MWD) and the lowest average molecular weight(MW), while by using a ferrum modified catalyst, the resulting polyethylene had the highest MW, reaching the ultra-high MW area. Vanadium and chromium modified catalysts demonstrated the best hydrogen response.
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Modification of the (SiO2/MgO/MgCl2)·TiClx Ziegler-Natta Polyethylene Catalysts Using the Third Metal Elements |
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| Authors: | Ting Fu Rui-hua Cheng Xue-lian He Zhen Liu Zhou Tian Bo-ping Liu |
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| Institution: | State Key Laboratory of Chemical Engineering, East China University of Science and Technology, Shanghai 200237, China |
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| Abstract: | Various (SiO2/MgO/MgCl2)·TiClx Ziegler-Natta catalysts modified by the third metal elements were synthesized by the co-impregnation of water-soluble magnesium and the third metal salts.Several key factors including the electronegativity of the third metal elements,catalyst performances in ethylene homo-polymerization,ethylene/1-hexene copolymerization and hydrogen response were systematically investigated.Both the catalyst performance and the polymer properties are influenced by the introduction of the third metal elements.Compared with the unmodified (SiO2/MgO/MgCh)·TiClx Ziegler-Natta catalyst,activity and 1-hexene incorporation are enhanced by the introduction of zirconium,vanadium,aluminum and chromium,while deteriorated by the addition of ferrum,nickel,molybdenum and tungsten.Correlations of the catalyst activities and 1-hexene incorporation ability with the electronegativity of the third metal elements are discovered.It is found that the lower electronegativity of the third metal elements leads to the catalyst with higher activity and higher α-olefm co-polymerization ability.The polyethylene produced by a nickel modified catalyst showed broad molecular weight distribution (MWD) and the lowest average molecular weight (MW),while by using a ferrum modified catalyst,the resulting polyethylene had the highest MW,reaching the ultra-high MW area.Vanadium and chromium modified catalysts demonstrated the best hydrogen response. |
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| Keywords: | Polyethylene Ziegler-Natta polymerization Copolymerization Kinetics |
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