CATALYST COMPONENTS FOR THE POLYMERIZATION OF OLEFINS AND CATALYSTS THEREFROM OBTAINED

摘要

A catalyst component comprising Ti, Mg, Al, Cl, and optionally OR^I groups in which R^I is a C1-C20 hydrocarbon group, optionally containing heteroatoms, up to an amount such as to give a molar OR^I /Ti ratio lower than 0.5, characterized by the fact that substantially all the titanium atoms are in valence state of 4, that the porosity (P_F), measured by the mercury method and due to pores with radius equal to or lower than 1µm, is at least 0.3 cm³/g, and by the fact that the Cl/Ti molar ratio is lower than 29. The said catalysts are characterized by high morphological stability under the low molecular weight ethylene polymerization conditions while at the same time maintaining characteristics of high activity.