Supported Polymerisation Catalysts

Abstract

A supported polymerisation catalyst system comprises: (a) a polymerisation catalyst, (b) a cocatalyst, and (c) a porous support, and is characterised in that the porous support has been pretreated with (i) a chemical dehydration agent and (ii) a hydroxy compound wherein the hydroxy compound is not a cocatalyst or component thereof. The preferred polymerisation catalyst is a transition metal compound for example a metallocene and by use of the supported catalyst systems improved activity may be achieved.

1 . A supported polymerisation catalyst system comprising
 (a) a polymerisation catalyst,   (b) a cocatalyst, and   (c) porous support,   characterised in that the porous support has been pretreated with (i) a chemical dehydration agent and (ii) a hydroxy compound wherein the hydroxy compound is not a cocatalyst or component thereof.   
   
   
       2 . A supported polymerisation catalyst system according to  claim 1  wherein the molar ratio of hydroxy compound to chemical dehydration agent is <2. 
   
   
       3 . A supported polymerisation catalyst system according to  claim 1  wherein the molar ratio of hydroxy compound to chemical dehydration agent is in the range 0.0001 to 0.2. 
   
   
       4 . A supported polymerisation catalyst system according to  claim 1  wherein the porous support is silica. 
   
   
       5 . A supported polymerisation catalyst system according to  claim 1  wherein the chemical dehydration agent is an organoaluminium compound. 
   
   
       6 . A supported polymerisation catalyst system according to  claim 5  wherein the organoaluminium compound is a trialkylaluminium compound. 
   
   
       7 . A supported polymerisation catalyst system according to  claim 1  wherein the polymerisation catalyst is a metallocene. 
   
   
       8 . A supported polymerisation catalyst system according to  claim 7  wherein the metallocene has the general formula: 
     
       
         
         
             
             
         
       
     
     wherein:—
 R′ each occurrence is independently selected from hydrogen, hydrocarbyl, silyl, germyl, halo, cyano, and combinations thereof, said R having up to 20 nonhydrogen atoms, and optionally, two R′ groups (where R′ is not hydrogen, halo or cyano) together form a divalent derivative thereof connected to adjacent positions of the cyclopentadienyl ring to form a fused ring structure; 
 X is a neutral η 4  bonded diene group having up to 30 non-hydrogen atoms, which forms a π-complex with M; 
 
     Y is —O—, —S—, —NR*—, —PR*—, 
     M is titanium or zirconium in the +2 formal oxidation state; 
     Z* is SiR* 2 , CR* 2 , SiR* 2 SIR* 2 , CR* 2 CR* 2 , CR*═CR*, CR* 2 SIR* 2 , or 
     GeR*2, wherein:
 R* each occurrence is independently hydrogen, or a member selected from hydrocarbyl, silyl, halogenated alkyl, halogenated aryl, and combinations thereof, said 
 R* having up to 10 non-hydrogen atoms, and optionally, two R* groups from Z* (when R* is not hydrogen), or an R* group from Z* and an R* group from Y form a ring system. 
 
   
   
       9 . A supported polymerisation catalyst system according to  claim 8  wherein M is titanium. 
   
   
       10 . A supported polymerisation catalyst system according to  claim 1 , wherein the cocatalyst is an aluminoxane, a borane or a borate. 
   
   
       11 . A supported polymerisation catalyst system according to  claim 1 , wherein the cocatalyst has the formula:
   (L*−H) +   d (A d− )   wherein   L* is a neutral Lewis base   (L*−H) + d is a Bronsted acid   A d−  is a non-coordinating compatible anion having a charge of d − , and d is an integer from 1 to 3.   
   
   
       12 . A supported polymerisation catalyst according to  claim 1  wherein the cocatalyst comprises ionic compounds having a cation and an anion wherein the anion has at least one substituent comprising a moiety having an active hydrogen. 
   
   
       13 . A supported polymerisation catalyst system comprising
 (a) a metallocene complex   (b) a cocatalyst   (c) a porous support, and   (d) a polymerisable monomer   
     characterised in that the porous support has been pretreated with (i) a chemical dehydration agent and (ii) a hydroxy compound. 
   
   
       14 . A supported polymerisation catalyst system according to  claim 13  wherein the polymerisable monomer has 2 to 10 carbon atoms. 
   
   
       15 . A supported polymerisation catalyst system according to  claim 14  wherein the polymerisable monomer is 1-hexene. 
   
   
       16 . A method for the preparation of a supported polymerisation catalyst system comprising the following steps:
 (a) pretreating a porous support with (i) a chemical dehydration agent and (ii) a hydroxy compound,   (b) addition of a cocatalyst, and   (c) addition of a polymerisation catalyst.   
   
   
       17 . A method according to  claim 16  wherein the polymerisation catalyst is a metallocene. 
   
   
       18 . A process for the polymerisation of olefin monomers selected from (a) ethylene, (b) propylene (c) mixtures of ethylene and propylene and (d) mixtures of (a), (b) or (c) with one or more other α-olefins, said process performed in the presence of a supported polymerisation catalyst system according to  claim 1 . 
   
   
       19 . A process for the polymerisation of ethylene or the copolymerisation of ethylene and α-olefins having from 3 to 10 carbon atoms, said process performed under polymerisation conditions in the present of a supported catalyst system according to  claim 1 . 
   
   
       20 . A process according to  claim 18  wherein the α-olefin is 1-hexene. 
   
   
       21 . A process according to  claim 18  performed in the gas phase.