Additional Methods for Activating Metallocene Single-Site Catalysts

5 Additional Methods for Activating Metallocene Single-Site Catalysts 

The work of Jordan and his coworkers was important because it supported the hypothesis that the zirconium cation was the active site in these singlesite catalysts and led to the search for finding other methods to form the zirconium cation without using MAO as the activating agent. 

Catalyst Type Temp (°C) Silica (yes/no) Ethylene (psi) 1-hexene Molar Activity (kgPE/g Zr(hr)) I-hexene mol% (DSC mp) 

In a follow up paper, Rissin and coworkers [41] postulate that the reaction of the aluminum alkyl and the magnesium alkyl produce an ionic material of the general formula shown below, which acts as a Lewis acid to activate the metallocene complex. 

Kissin also explains that the silica-supported catalysts are not suitable for a high-temperature (80-90°C) hydrocarbon slurry polymerization process, as the zirconium catalyst component is not chemically fixed to the silica surface and the zirconium catalyst component is extracted from the silica due to its solubility in the hydrocarbon medium resulting in poor polymer particle morphology. However, the catalyst may be retained in the silica pores during a gas-phase polymerization process and, therefore, may provide good particle morphology necessary for a gas-phase process. Consequently, this unique cocatalyst activator may be able to provide a 

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