Components of catalysts for the polymerization of olefins

A component useful in preparing a catalyst for the polymerization of olefins, said component being obtained by contacting a transition metal halide which is a titanium or vanadium halide in which the metal has a valence lower than 4, with a support the essential support material of which is an active MgCl.sub.2, the titanium or vanadium halide being used in an amount less than 50% by weight with respect to the MgCl.sub.2, and the MgCl.sub.2 being characterized in that, in its X-rays powder spectrum, the diffraction line which, in the spectrum for the normal inert MgCl.sub.2, has the highest intensity and appears at a lattice distance (d) of 2.56 .ANG. is less intense and in its place a broadened halo appears in a range of lattice distances (d) comprised from d=2.56 .ANG. to d=2.95 .ANG..

A component useful in preparing a catalyst for the polymerization of olefins, said component being prepared by contacting a transition metal halide which is a titanium or vanadium halide in which the metal has a valence lower than 4, with a support the essential support material of which is an active MgBr.sub.2, the titanium or vanadium halide being used in an amount less than 50% by weight with respect to the MgBr.sub.2, and the MgBr.sub.2 being characterized in that, in its X-rays powder spectrum, the diffraction line which in the spectrum for the normal inert MgBr.sub.2 has the highest intensity and appears at a lattice distance d of 2.93 .ANG. is less intense and in its place a broadened halo appears in a range of lattice distances (d) comprised from d=2.80 .ANG. to d=3.25 .ANG..

Catalysts for the polymerization of olefins, consisting of the product obtained by mixing

• (a) a hydride or organometallic compound of a metal belonging to one of Groups I to III inclusive of the Mendelyeev Periodic System with
• (b) the product obtained by contacting a titanium or vanadium halide in which the metal has a valence lower than 4, with an active form of an anhydrous magnesium dihalide, the transition metal halide being used in an amount less than 50% by weight with respect to the magnesium dihalide, and the active magnesium dihalide being characterized in that in its X-rays powder spectrum the most intense diffraction line present in the spectrum of the normal non-active magnesium dihalide is less intense and, in its place, a broadened halo appears.

A process for the polymerization of olefins comprising polymerizing an olefin in the presence of a catalyst consisting of the product obtained by mixing

• (1) a hydride or organometallic compound of a metal belonging to Groups I-III inclusive of the Mendelyeev Periodic System with
• (2) the product obtained by mechanical co-comminution of a titanium or vanadium halide in which the metal has a valence lower than 4 with a magnesium dihalide until the most intense diffraction line in the X-rays powder spectrum of the normal non-comminuted magnesium dihalide is less intense and in its place a broadened halo appears, said titanium or vanadium halide being used in an amount less than 50% by weight with respect to the magnesium dihalide.

Process for preparing components of catalysts for the polymerization of olefins comprising contacting a transition metal halide selected from titanium and vanadium halides in which the metal has a valence lower than 4, with an anhydrous magnesium dihalide in an active form characterized in that in the X-rays powder spectrum thereof the most intense diffraction line present in the spectrum of the normal non-active magnesium halide is less intense and, in its place, a broadened halo appears, the titanium or vanadium halide being used in an amount less than 50% by weight with respect to the magnesium dihalide.