Reivindicaciones

1. Heterogeneous catalytic system obtainable by reacting a porous inorganic support with an alumoxane and subsequently supporting at least one metallocene compound thereon, characterized in that the metallocene compound is defined by the following general formulas: (LR<k>)<z>[LR<k-f>(R<I>OSiR<II> <3>)<f>]<x>MX<y> I <img class="EMIRef" id="582232127-ib0028" /> <img class="EMIRef" id="582232127-ib0029" /> wherein: L, equal to or different from each other, is selected from the group comprising: cyclopentadienyl, indenyl, tetrahydroindenyl, fluorenyl, octahydrofluorenyl or benzoindenyl; each R is independently selected from hydrogen, C<1>-C<20> alkyl, C<3>-C<20> cycloalkyl, C<6>-C<20> aryl, C<3>-C<20> alkenyl, C<7>-C<20> arylalkyl, C<7>-C<20> alkylaryl, C<8>-C<20> arylalkenyl, linear or branched, optionally substituted by 1 to 10 halogen atoms, or a group SiR<II>3 ; each RI , equal to or different from each other, is a divalent aliphatic or aromatic hydrocarbon group containing from 1 to 20 carbon atoms, optionally containing from 1 to 5 heteroatoms of groups 14 to 16 of the periodic table of the elements and boron ; preferably it is: C<1>-C<20> alkylene, C<3>-C<20>cycloalkylene, C<6>-C<20> arylene, C<7>-C<20> alkenyl, C<7>-C<20> arylalkylene, or alkylarylene, linear or branched, or a group SiR<II>2 ; each RII is independently selected from C<1>-C<20> alkyl , C<3>-C<20> cycloalkyl, C<6>-C<20> aryl, C<3>-C<20> alkenyl, C<7>-C<20> arylalkyl, C<8>-C<20> arylalkenyl or C<7>-C<20> alkylaryl, linear or branched; preferably R<II> is methyl, ethyl or isopropyl; each Q is independently selected from B, C, Si, Ge, Sn; M is a metal of group 3, 4 or 10 of the Periodic Table, Lanthanide or Actinide; each X is independently selected from: hydrogen, chlorine, bromine, OR<II>, NR<II>2 , C<1>-C<20> alkyl or C<6>-C<20> aryl; L' is N or O; when L is cyclopentadienyl k is equal to 5, when L is indenyl k is equal to 7, when L is fluorenyl or benzoindenyl k is equal to 9, when L is tetrahydroindenyl k is equal to 11 and when L is octahydrofluorenyl, k is equal to 17; z is equal to 0, 1 or 2; x is equal to 1, 2 or 3; y is equal to 1, 2 or 3; x + y + z is equal to the valence of M; m is an integer which can assume the values 1, 2, 3 or 4; a and b are integers whose value ranges from 0 to k-1; f is an integer whose value ranges from 1 to k; g is an integer whose value ranges from 0 to 1; c and e are equal to 0 or 1; a + b + c is at least 1; a + g + c is at least 1; d is equal to 0, 1 or 2; when Q is B then c + d = 1; when Q is C, Si, Ge or Sn, then c + d = 2; when L' is N, then g + e = 1; when L' is O, then g = 0 and e = 0. 2. Heterogeneous catalytic system according to claim 1 wherein the group R<I>OSiR<II>3 is selected from CH<2>-CH<2>-OSiMe<3>, CH<2>-CH<2>-CH<2>-OSiMe<3>, CH<2>-O-CH<2>-OSiMe<3>, O-CH<2>-CH<2>-OSiMe<3>, SiMe<2>-CH<2>-CH<2>-OSiMe<3>, SiMe<2>-OSiMe<3> or SiMe<2>-CH<2>-CH<2>-CH<2>-0SiMe<3>. 3. Heterogeneous catalytic system according to claims 1-3 wherein M is titanium, zirconium or hafnium. 4. Heterogeneous catalytic system according to claims 1-4 wherein the alumoxane is represented by the formulas: (RAIO)<n> R(R-Al-O)<m>AlR<2> wherein R is alkyl or aryl group containing from 1 to 20 carbon atoms; n ranges from 1 to 40, and m ranges from 3 to 40. 5. Heterogeneous catalyst system according to claims 1-5 wherein the inorganic support is selected from silica, alumina, silica alumina, aluminium phosphates and mixtures thereof. 6. Heterogeneous catalyst system according to claims 1-6 wherein the content in transition metal is comprised between 0.01 and 3% by weight. 7. Heterogeneous catalyst system according to claim 7 wherein the content in transition metal is comprised between 0.1 and 1% by weight. 8. Process for the polymerization of alpha olefins in slurry or in gas phase characterized by the use of the heterogeneous catalyst system of claims 1-8. 9. Metallocene compounds according to the following formulas: (LR<k>)<z>[LR<k-f>(R<I>OSiR<II> <3>)<f>]<x>MX<y> I <img class="EMIRef" id="582232127-ib0030" /> <img class="EMIRef" id="582232127-ib0031" /> wherein: L, equal to or different from each other, is selected from the group comprising: cyclopentadienyl, indenyl, tetrahydroindenyl, fluorenyl, octahydrofluorenyl and benzoindenyl; each R is independently selected from hydrogen, C<1>-C<20> alkyl, C<3>-C<20> cycloalkyl, C<6>-C<20> aryl, C<3>-C<20> alkenyl, C<7>-C<20> arylalkyl, C<7>-C<20> alkylaryl, C<8>-C<20> arylalkenyl, linear or branched, optionally substituted by 1 to 10 halogen atoms, or a group SiR<II>3 ; each RI , equal to or different from each other, is a divalent aliphatic or aromatic hydrocarbon group containing from 1 to 20 carbon atoms, optionally containing from 1 to 5 heteroatoms of groups 14 to 16 of the periodic table of the elements and boron ; preferably it is: C<1>-C<20> alkylene, C<3>-C<20>cycloalkylene, C<6>-C<20> arylene, C<7>-C<20> alkenyl, C<7>-C<20> arylalkylene, or alkylarylene, linear or branched, or a group SiR<II>2 ; each RII is independently selected from C<1>-C<20> alkyl , C<3>-C<20> cycloalkyl, C<6>-C<20> aryl, C<3>-C<20> alkenyl, C<7>-C<20> arylalkyl, C<8>-C<20> arylalkenyl or C<7>-C<20> alkylaryl, linear or branched; preferably R<II> is methyl, ethyl or isopropyl; each Q is independently selected from B, C, Si, Ge, Sn; M is a metal of group 3, 4 or 10 of the Periodic Table, Lanthanide or Actinide; preferably it is titanium, zirconium or hafnium; each X is independently selected from: hydrogen, chlorine, bromine, OR<II>, NR<II>2 , C<1>-C<20> alkyl or C<6>-C<20> aryl; L' is N or O when L is cyclopentadienyl k is equal to 5, when L is indenyl k is equal to 7, when L is fluorenyl or benzoindenyl k is equal to 9, when L is tetrahydroindenyl k is equal to 11 and when L is octahydrofluorenyl, k is equal to 17; z is equal to 0, 1 or 2; x is equal to 1, 2 or 3; y is equal to 1, 2 or 3; x + y + z is equal to the valence of M; m is an integer which can assume the values 1, 2, 3 or 4; a and b are integers whose value ranges from 0 to k-1; f is an integer whose value ranges from 1 to k; g is an integer whose value ranges from 0 to 1; c and e are equal to 0 or 1; a + b + c is at least 1; a + g + c is at least 1; d is equal to 0, 1 or 2; when Q is B then c + d = 1; when Q is C, Si, Ge or Sn, then c + d = 2; when L' is N, then g + e = 1; when L' is O, then g = 0 and e = 0. characterized in that at least one L is a fluorenyl, benzoindenyl or octahydrofluorenyl ring, optionally substituted by C<1>-C<20> alkyl , C<3>-C<20> cycloalkyl, C<6>-C<20> aryl, C<3>-C<20> alkenyl, C<7>-C<20> arylalkyl, C<8>-C<20> arylalkenyl or C<7>-C<20> alkylaryl.