MI Puke^1,2, XU Sheng², LIU Min², CHENG Lin^1*

(1.School of Materials Science & Engineering, Huaqiao University, Xiamen 361021, China; 2. School of Materials Science & Engineering, East China University of Science and Technology, 130 Meilong Road, Shanghai 200237, China )

Abstract: The kinetics of ethylene polymerization catalyzed by supported binuclear metallocene catalyst [(η⁵-C₅H₅) ZrCl₂]₂[μ, μ-(SiMe₂)₂ (η⁵-allyl C₅H₂)₂]/MAO/SiO₂ in slurry phase was investigated. The effects of polymerization factors, such as diffusion index, polymerization pressure and temperature on the kinetics were studied. The kinetics parameters such as reaction order (n), the apparent activation energy (Ea) and the chain propagation rate constant (Kp) were determined and the concentration of active site (C*) was obtained by kinetic extrapolation method. The result indicates that the supported binuclear metallocene/MAO catalyst system exhibit a higher catalytic activity than that of single center system, attributed to its higher C* concentration and higher Kp. The slurry phase polymerization reaction rates shows 1.11 order dependency on monomer concentration, and Ea = 72.47 kJ/mol, C* = 0.33 mol/mol and Kp=1.06×10⁶ L•(mol•h)^-1 are found.

Key words: kinetics; ethylene polymerization; supported binuclear metallocene

E-mail: xusheng@ecust.edu.cn

Journal of Molecular Catalysis, Vol. 26, Issue 6, 2012, 537-545