Catalysts for the polymerization of olefins and process for the preparation thereof

A catalyst for the polymerization of olefins comprising the product obtained by contacting the following components:

• (A) a cyclopentadienyl compound of formula (I):
• (C5R1x−mH5−x)R2m(C5R1y−mH5−y)nMQ3−n (I)
• wherein M is a metal selected from the group consisting of Ti, Zr, and Hf;
• C5R1x−mH5−x and C5R1y−mH5−y are equally or differently substituted cyclopentadienyl rings;
• the substituents R1, the same or different from each other, are selected from the group consisting of linear or branched, saturated or unsaturated C1-C20 alkyl, C6-C20 aryl, C7-C2alkylaryl or C7-C20 arylalkyl radicals, optionally containing one or more atoms belonging to groups 13-16 of the Periodic Table of the Elements (new IUPAC notation);
• or two or four substituents R1 of the same cyclopentadienyl group form one or two rings, having 4 to 6 carbon atoms;
• R2 is a bridging group between the two cyclopentadienyl rings and is selected from the group consisting of CR32, C2R34, SiR32, Si2R34, GeR32, Ge2R34, R32SiCR32, NR1 and PR1, wherein the substituents R3, the same or different from each other, are hydrogen or have the same meaning as R1, or two or four substituents R3 form one or two rings, having 3 to 6 carbon atoms;
• the substituents Q, the same or different from each other, are selected from the group consisting of hydrogen, halogen, OH, SH, R1, OR1, SR1, NR12 and PR12;
• m is 0 or 1;
• n is 0 or 1, being 1 when m=1;
• x ranges from (m+1) to 5;
• y ranges from m to 5;
• (B) one or more organometallic aluminum compounds of formula (II);
• AlR43−ZHZ (II)
• wherein the stibstituents R4, the same or different from each other, are linear or branched, saturated or unsaturated C1-C20 alkyl or C7-C20 alkylaryl radicals, optionally containing Si or Ge atoms, at least one of the substituents R4 being different from a straight alkyl group;
• z is 0 or 1;
• and
• (C) water;
• the molar ratio between the organometallic aluminum compound and the water being comprised between 1:1 and 100:1;
• the catalyst being obtained by a process comprising the following steps:
• (i) contacting component (A) with part of component (B) in the absence of component (C);
• (ii) contacting part of component (B) with component (C) in the absence of component (A);
• and
• (iii) contacting the products obtained in steps (i) and (ii);
• wherein the components (B) used in steps (i) and (ii) can be the same or different from each other, with the proviso that component (C) is not adsorbed or absorbed on a silica support.