Supported olefin polymerization catalyst composition

A process for the preparation of a supported olefin polymerization catalyst composition, comprising a support, a metallocene, and an alumoxane, wherein a support comprising a porous carrier is contacted, in any order, with at least one member of the group consisting of

• (a) an organometallic compound of the general formula (1):
• R1MXv−1 (1)
• wherein each R is the same or different and is a C1-C10 alkyl group;
• M is a metal of Group 1, 2, 12 or 13 of the Periodic Table;
• each X is the same or different and one of a halogen atom, a hydrogen atom, a hydroxyl radical or a C1-C8 hydrocarbyloxy group;
• I is 1, 2 or 3;
• v is the oxidation number of the metal M,
• and with a complex solution of at least
• (b) a metallocene of the general formula (2):
• (CpY)mM′X′nZo
• wherein each CpY is the same or different and is one of a mono- or polysubstituted, fused or non-fused, homo- or heterocyclic cyclopentadienyl, indenyl, tetrahydro-indenyl, fluorenyl, or octahydrofluorenyl ligand, which ligand is substituted at its cyclopentadienyl ring with at least one substituent Y which is one of a —OR′, —SR′, —NR′2, or —PR′2 radical, each R′ being the same or different and is one of a tri-C1-C8 hydrocarbylsilyl group or a tri-C1-C8 hydrocarbyloxy silyl group;
• M′ is a transition metal of Group 4 of the Periodic Table and bound to the ligand CpY at least in an N5 bonding mode;
• each X′ is the same or different and is one of a hydrogen atom, a halogen atom, a C1-C8 hydrocarbyl group, a C1-C8 hydrocarbylheteroatom group or a tri-C1-C8 hydrocarbyl silyl group or two X′ form a ring with each other;
• Z is a bridge atom or group between two CpY ligands, or one CpY ligand and the transition metal M′;
• m is 1 or 2;
• o is 0 or 1′ and n is 4-m if there is no bridge Z or Z is a bridge between two CpY ligands, or n is 4-m-o if Z is a bridge between one CpY ligand and the transition metal M′, and
• (c) an alumoxane of one of the following formulas (3):
• wherein each R″ and each R′″ is the same or different and is a C2-C12 alkyl group;
• and p is an integer between 1 and 40;
• and recovering said supported olefin polymerization catalyst composition.