The Catalyst Solid Component

1 Preparation of Catalysts for the Synthesis of Polyolefins Consisting of MgCl2 anf Titanium Compounds 

Scientific and, particularly, patent literature report several detailed outlines of methods for the preparation of catalysts mainly consisting of MgCl2 and titanium compounds. Thus, we shall not go into details, since adequate lists reporting a great deal of cases have been already published 23 24 25). 

TiCl4/MgCl2 catalysts may be used for the polyethylene synthesis, but not for the preparation of isotactic polypropylene. In fact, although these catalysts are highly reactive for the propylene polymerization, they are not stereospecific enough to give a commercially interesting product. 

Stereospecificity requires the presence of a suitable Lewis base (aromatic esters being the most commonly used) in one of the preparation phases. In particular, any of the following general procedures may be used  

The last two procedures require final washing with hydrocarbons in order to remove excess TiCl4 not bonded to the support. 

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The work is divided into three parts. The first (Chapters 3 and 4) covers the catalyst (solid components) with particular regard to preparation, structure and role of the components. The second part (Chapter 5) deals with the reactions which take place between catalyst and cocatalyst and give rise to the formation of polymerization centers. The third part regards the polymerization and, apart from a discussion of number and nature of the active centers, reports the hypotheses about the most probable reaction mechanisms as a function of various kinetic parameters. 

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