Catalyst system

A supported catalyst system comprising:

• (i) a metallocene complex;
• (ii) a cocatalyst system comprising a boron containing cocatalyst and a methylaluminoxane cocatalyst;
• and
• (iii) an inorganic porous support;
• wherein the metallocene complex is of formula (I):
• wherein
• each X independently is a sigma-donor ligand;
• L is —R′2Si—, and each R′ is independently a C1-C6-alkyl, C5-6-cycloalkyl, or C6-aryl group;
• each Ar independently is a phenyl ring or a 5 or 6 membered heteroaryl ring;
• each R1 is bonded to a carbon and independently is hydrogen, or a linear or branched C1-C6-alkyl group;
• each R2 independently is a CHR8′—R8 group, with R8 being H, or a linear or branched C1-6-alkyl group, and R8′ is H or a C1-6 alkyl;
• R3 is a linear or branched C1-C6-alkyl group, a C7-20-arylalkyl group, a C7-20-alkylaryl group, or C6-C20-aryl group;
• R4 is a C(R9)3 group, with each R9 independently being a linear or branched C1-C6-alkyl group;
• R5 and R6 are both hydrogen, or R5 and R6 taken together form a 5 membered saturated carbon ring;
• R7 is a linear or branched C1-C6-alkyl group, or an aryl or heteroaryl group having 3 to 20 carbon atoms optionally substituted by one to three groups R11;
• and
• each R11 independently is hydrogen, or a linear or branched C1-C6-alkyl group;
• wherein the boron containing cocatalyst is either of formula (B) or a borate containing an anion of formula (C):
• BY3 (B)
• (Z)4B— (C)
• wherein
• each Y independently is a hydrogen atom, an alkyl group of from 1 to about 20 carbon atoms, an aryl group of from 6 to about 15 carbon atoms, alkylaryl, arylalkyl, haloalkyl or haloaryl each having from 1 to 10 carbon atoms in the alkyl radical and from 6-20 carbon atoms in the aryl radical or fluorine;
• or
• Z is an optionally substituted phenyl derivative, said substituent being a halo-C1-6-alkyl or halo group, and as counterions protonated amine or aniline derivatives.