Magnesium-Containing Compounds that Provide High-Activity Ziegler Catalysts

7 Magnesium-Containing Compounds that Provide High-Activity Ziegler Catalysts 

A wide variety of different magnesium compounds have been investigated to produce highly-active ethylene polymerization catalysts. The characteristics of the polymers produced with highly-active Mg/Ti-based catalysts are determined by the type of magnesium-containing compound used in the catalyst preparation. But the important characteristics of the finished solid catalyst material include polymerization kinetic profile, particle size, particle size distribution, and particle shape (spherical or irregular). 

The preparations involve a magnesium alkyl (MgR MgR /AlR or RMgX) and a titanium-chloride compoxmd as the source of Ti, but mixtures of a titanium chloride compound and a titanium alkoxide compound have also been used. 

Two early examples of providing a high-activity ethylene polymerization catalyst by reducing TiCl with a magnesium-alkyl-containing compoimd are illustrated below. 

The reduction of TiCl with diphenylmagnesium to produce highly-active ethylene polymerization catalysts was reported by scientists L. Petkov, R. Kyrtcheva, Ph. Radenkov and D. Dobreva [38,39] at SEC Neftochim Research Centre in Bourgas, Bulgaria. This catalyst exhibited an activity of about 30,000 g PE/gTi for a 0.25 hr polymerization at 75°C and ethylene pressure of 5 kg/cm  

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Most likely, these early magnesium-containing Ziegler catalysts provided the necessary data that led to the discovery of additional very highly-active Ziegler catalysts, which were reported from about 1965-1980 from many different research laboratories around the world, with the common feature that all of these catalysts were based on magnesium and titanium compounds. 

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