Indirect Synthesis of Bis(2-PhInd)ZrCl2 Metallocene Catalyst, Kinetic Study and Modeling of Ethylene Polymerization

Bis(2-phenylindenyl)zirconium dichloride (bis(2-PhInd)ZrCl2) catalyst was synthesized via the preparation of bis(2-phenylindenyl)zirconium dimethyl (bis(2-PhInd)ZrMe2) followed by chlorination to obtain the catalyst. Performance of the catalyst for ethylene polymerization and its kinetic behavior were investigated. Activity of the catalyst increased as the [Al]:[Zr] molar ratio increased to 2333:1, followed by reduction at higher ratios. The maximum activity of the catalyst was obtained at a polymerization temperature of 60 degrees C. The rate-time profile of the reaction was of a decay type under all conditions. A general kinetic scheme was modified by considering a reversible reaction of latent site formation, and used to predict dynamic polymerization rate and viscosity average molecular weight of the resulting polymer. Kinetic constants were estimated by the Nelder-Mead numerical optimization algorithm. It was shown that any deviation from the general kinetic behavior can be captured by the addition of the reversible reaction of latent site formation. Simulation results were in satisfactory agreement with experimental data.