CONTROLO E IDENTIDADE: A NO CONFORMIDADE DURANT E A ADOLESCNCI A

Catalyst systems of the Ziegler-Natta type comprise as active constituentsa) a solid component comprising a compound of titanium or vanadium, a compound of magnesium, a particulate inorganic oxide as support and an internal electron donor compound,and as cocatalystb) an aluminum compound andc) if desired, a further, external electron donor compound,wherein the particulate, inorganic oxide used has a specific surface area of from 350 to 1000 m2/g and a mean particle diameter {overscore (D in the range from 5 to 60 mum and comprises particles which are composed of primary particles having a mean particle diameter {overscore (d in the range from 1 to 10 mum and contain voids or channels between the primary particles, where the macroscopic proportion of voids or channels having a diameter of greater than 1 mum in the particles of the inorganic oxides is in the range from 5 to 30% by volume and the molar ratio of the compound of magnesium to the particulate, inorganic oxide is from 0.5:1 to 2.0:1.