Process for the manufacture of a catalytic solid, catalytic solid and process for (co)polymerisation of olefins by means of this catalytic solid

The process for the manufacture of a catalytic solid, comprising:

• a) mixing at least one magnesium compound chosen from the group consisting of Mg oxide and compounds of formulae MgX.sub.n (O--R).sub.2-n, and at least one transition metal compound selected from the group consisting of compounds of formulae MY.sub.x (O--R').sub.t-x and M'O.sub.y (O--R").sub.s-2y in which
• X denotes a halogen
• each of M and M' denotes a transition metal chosen from the group consisting of the elements of groups IVB and VB of the Periodic Table, the valency of which is at least equal to 4
• Y denotes a halogen or a group (O--R'")
• each of R, R', R" and R'" denotes an alkyl, aryl or cycloalkyl group containing up to 20 carbon atoms
• O.ltoreq.n.ltoreq.2
• O.ltoreq.x.ltoreq.t, t being equal to the valency of M
• O.ltoreq.y.ltoreq.s/2, being equal to the valency of M', to obtain a solution comprising a complex of said at least one magnesium compound with said at least one transition metal compound,
• b) reducing and halogenating the solution of the complex thus obtained by contacting it with a reducing-halogenating agent, in order to precipitate a catalytic solid, comprising an amorphous coprecipitate of a halogen compound of a transition metal M or M' in the trivalent state, a halogen compound of a transition metal M" in the trivalent state, and a magnesium halide, and
• c) isolating the precipitated catalytic solid thus obtained from the solution,
• wherein the reducing-halogenating agent consists essentially of at least one complex of empirical formula M"(A)Al.sub.2 Cl.sub.8 in which
• M" denotes a transition metal of group IVB of the Periodic Table, and
• A denotes an aromatic hydrocarbon.