CATALYST COMPRISING A MAGNESIUM COMPOUND AND A TRANSITION METAL HALIDE, PROCESS FOR THE PREPARATION OF SAID CATALYST, CATALYTIC SYSTEM COMPRISING SAID CATALYST AND POLYMERISATION PROCESS USING SAID CATALYTIC SYSTEM

摘要

A catalyst comprising the product obtained by bringing into contact (a) a compound of magnesium comprising at least one species selected from the group consisting of magnesium monohalides (MgX), halo-magnesium hydrides (HMgX) and magnesium hydride (MgH2), X being a halogen and the said species MgX or HMgX being obtained by thermal decomposition of a powdery organo-magnesium halide R1MgX wherein R1 is an organic radical; and (b) at least one halide of a transistion metal selected from the group consisting of titanium and vandium, the valency of said metal in said halide being lower than or equal to 3, the quantities of (a) and (b) being such that the atomic ratio of magnesium to said transistion metal is between 1 and 25, and a catalyst system including the catalyst that is suitable for use in the polymerization of olefins and particularly ethylene.