| abstract |
Spherical components of catalysts for the polymerization of olefins comprising:n (a) a vanadium compound selected from the compounds of formula VOX₂Y or VX n Y n-4n , where X is Cl or Br and Y is Cl, Br, OR or NR I ₂ (b) MgCl₂ in spherical form. Said components have an average diameter greater than 1 µm, a surface area of at least 10 m²/g, a porosity of at least 0.1 g/cm³ and an X-ray spectrum having particular characteristics. |