| abstract |
Polymerization catalysts, particularly catalysts for the polymerization of olefins, are disclosed. The catalysts are prepared by mixing n (A) an organometallic compound or hydride of a metal belonging to Groups I to III of the Mendelyeev Periodic Table; with n (B) the product obtained by contacting (1) an addition product obtained by reacting a di-, tri-, or tetravalent titanium compound with an electron-donor compound, with (2) an anhydrous magnesium halide, in particular anhydrous MgCl 2 or MgBr 2 , which is either preactivated or mixed with the Ti compound under conditions which result in its activation; or by contacting (A) with n (B') the product obtained by contacting a di-, tri-, or tetravalent Ti compound with an electron-donor compound and a support consisting of an anhydrous Mg halide, in particular MgCl 2 or anhydrous MgBr 2 , which is either preactivated or mixed with the Ti compound and electron-donor under conditions such that the Mg halide is activated. |