Abstract: Catalysts for the polymerization of olefins are disclosed, which comprise the reaction product of:(A) a bridged and/or substituted cyclopentadienyl compound of titanium, zirconium or hafnium;(B) an organometallic aluminum compound of the formula (II):Al(CH.sub.2 --CR.sup.4 R.sup.5 R.sup.6).sub.w R.sup.7.sub.y H.sub.z(II)wherein in the (CH.sub.2 --CR.sup.4 R.sup.5 R.sup.6) groups, which are the same or different, R.sup.4 is an alkyl, alkenyl or arylalkyl group having from 1 to 10 carbon atoms, R.sup.5 is an alkyl, alkenyl, aryl, arylalkyl or alkylaryl group having from 3 to 50 carbon atoms which is different from a straight alkyl or alkenyl group and, optionally, R.sup.4 and R.sup.5 fused together can form a ring having from 4 to 6 carbon atoms, R.sup.6 is hydrogen or an alkyl, alkenyl or arylalkyl group having from 1 to 10 carbon atoms, the R.sup.

Abstract: Multistage process for the polymerization of one or more olefins of the formula CH.sub.2 .dbd.CHR, in which R is hydrogen or an alkyl, cycloalkyl or aryl group having from 1 to 10 carbon atoms, comprising:(A) a first stage of polymerization, in which a first olefin polymer is prepared in the presence of titanium catalyst or vanadium catalyst;(B) a treatment stage in which the catalyst used previously is deactivated and in which a metallocene compound is supported on the olefin polymer produced in stage (A); and(C) a second stage of polymerization in which one or more olefins are polymerized in the presence of the product obtained from stage (B).

Abstract: Process for preparing elastomeric copolymers of ethylene with .alpha.-olefins CH.sub.2 .dbd.CHR, optionally containing minor proportions of a diene, characterized by the use during the polymerization of a catalyst comprising the reaction product of:(I) a solid component comprising VCl.sub.3 supported on a magnesium dihalide in spherical or spheroidal shape, in active form;(II) an alkyaluminum compound;(III) optionally a halohydrocarbon.VCl.sub.3 is precipitated on said magnesium dihalide by heating VCl.sub.4 solutions in inert hydrocarbon solvents.