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The Characteristics of Metallocene/Ziegler-Natta Hybrid Catalysts Supported on the Recrystallized MgCl2
Division of Chemical Engineering, College of Engineering, Seoul National University, Seoul, Korea
Korean Journal of Chemical Engineering, September 1999, 16(5), 562-570(9), 10.1007/BF02708132
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Abstract
A metallocene catalyst or metallocene/Ziegler-Natta hybrid catalyst supported on MgCl2 was studied for application to the commercial slurry phase process and to the control of MWD of the polymer produced. The MgCl2 support was prepared by the recrystallization mehtod with different solvents: alcohols and H2O. The recrystallized MgCl2 support was pretreated with trisobutylaluminum (TiBAL) or trimethylaluminum (TMA), methylaluminoxane (MAO), to give different supporting environments. Metallocene/Ziegler-Natta hybrid catalysts on MgCl2 were prepared by first supporting the metallocene catalyst, followed by the Ziegler-Natta catalyst after pretreatment with an alkylaluminum compound. The type of solvent plays a role in providing a suitable environment in the support for impregnating catalysts. The hybrid catalyst, whose support was recrystallized in n-propanol (n-PrOH) and pretreated with TiBAL, showed the highest molar ratio of Zr/Ti=1/2.71. But the hybrid catalyst, whose support was recrystallized in H2O and pretreated with MAO, showed the best hybrid effect showing a variety of bimodal peaks in proportion to the ratio of MAO/TEA in GPC analysis. This effect might be due to steric factor and polarity of solvent, as well as the pretreatment material. It is concluded that the MWD of polyethylene produced by metallocene/Ziegler-Natta hybrid catalyst that is supported on MgCl2, can be controlled by regulating the amounts of MAO and TEA added as cocatalysts and by the use of different solvents and pretreatment materials.
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References
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ICDD (International Centre for Diffraction Data): PDF (Powder Diffraction File) No. 25-0515
ICDD: PDF No 01-1210
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Bart JC, Roovers W, J. Mater. Sci., 30(11), 2809 (1995)
Cho HS, Chung JS, Han JH, Ko YG, Lee WY, J. Appl. Polym. Sci., 70(9), 1707 (1998)
Chung JS, Song IK, Lee WY, Park HM, Macromol. Chem. Phys., 196, 1205 (1995)
Chien JCW, He D, J. Polym. Sci. A: Polym. Chem., 29, 1585 (1991)
Guyot A, Bobicon C, Spitz R, Kaminsky W, "Transition Metals and Organometallics as Catalysts for Olefin Polymerization," Ed., Springer-Verlag, Berlin, 13 (1987)
Magalhaes DNT, Filho ODC, Coutinho FM, Eur. Polym. J., 27, 1093 (1991)
Park HM, Lee WY, Eur. Polym. J., 28, 1417 (1992)
Soga K, Kaminaka M, Macromol. Chem. Rapid Commun., 13, 221 (1992)
Soga K, Kaminaka M, Macromol. Chem. Phys., 195, 1369 (1994)
Soga K, Kaminaka M, Makromol. Chem., 194, 1745 (1993)
Woo SI, Ko YS, Han TK, Park JW, Huh WS, "Olefin Polymerization Catalyzed over Zeolite-Supported Metallocene Catalysts," Proceeding of Metallocenes '96 (1996)
Yoon JS, Oh JK, Hong KP, Lee IM, Korean J. Chem. Eng., 13(2), 207 (1996)
Zambelli A, Pellecchia C, Oliva L, Longo P, Grassi A, Makromol. Chem., 192, 223 (1991)
ICDD (International Centre for Diffraction Data): PDF (Powder Diffraction File) No. 25-0515
ICDD: PDF No 01-1210
ICDD: PDF No 01-0947
