Catalytic solid for use in the polymerization of alpha-olefines, process for preparing it and process for the polymerization of alpha-olefines in the presence of a catalyst system containing this solid

In a process for the preparation of a catalytic solid by reacting effective amounts of a magnesium halide (M) with an oxygenated organic compound of titanium (T) to form a solution to which is added a precipitating agent selected from a polymeric compound of silicon (S) to form a solid complex (C) containing magnesium, a halogen, titanium, and silicon;

• the improvement comprising converting the solid complex (C) into a microporous catalytic solid by contacting the solid complex (C) with a compound (H) selected from the group consisting of the halogenated compounds of titanium and silicon, and further contacting the solid complex (C) with a supplemental organoaluminum compound (A) and separating said microporous catalytic solid from said solution.

In a catalytic solid prepared by reacting effective amounts of a magnesium halide (M) with an oxygenated organic compound of titanium (T) to which is added a polymeric compound of silicon (S) to form a solid complex (C) containing magnesium, a halogen, titanium, and silicon;

• the improvement comprising converting the solid complex (C) into a microporous catalytic solid containing aluminum by contacting the solid complex (C) with a compound (H) selected from the group consisting of the halogenated compounds of titanium and silicon, and further contacting the solid complex (C) with a supplemental organoaluminum compound (A) of the general formula
• AlR.sub.n.sup.6 X.sub.3-n
• wherein R.sup.6 is a hydrocarbon radical, X is a halogen and 0<n.ltoreq.3.

In a catalytic solid prepared by reacting effective amounts of a magnesium halide (M) with an oxygenated organic compound of titanium (T) to form a solution to which is added a precipitating agent selected from a polymeric compound of silicon (S) to form a solid complex (C) containing magnesium, a halogen, titanium, and silicon;

• the improvement comprising converting the solid complex (C) into a microporous catalytic solid by contacting the solid complex (C) with a compound (H) selected from the group consisting of the halogenated compounds of titanium and silicon, and further contacting the solid complex (C) with a supplemental organoaluminum compound (A) and separating said microporous catalytic solid from said solution.