| 摘要 |
A catalyst component comprising Ti, Mg, Cl, and optionally OR1 groups in which R1 is a C1-C20 hydrocarbon group up to an amount such as to give a molar ORI/Ti ratio lower than 0.5, characterized by the following properties: surface area, determined by BET method, of lower than 80 m2/g,-a total porosity (PT), measured by the mercury method, in the range of 0.60-1.50 cm3/g--a difference (PT-PF) of higher than 0.1 in which PT is the total porosity and PF is the porosity due to pore with radius equal to or less than 1 μm;-an amount of Ti in the catalyst component of less that 10 %wt based on the total weight of catalyst component. The said catalyst components show high morphological stability under the low molecular weight ethylene polymerization conditions while at the same time maintaining characteristics of high activity.
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