Olefin polymerization catalyst compositions and method of preparation

Abstract

A method of making a solid procatalyst composition for use in a Ziegler-Natta olefin polymerization catalyst composition, said method comprising: contacting a solid precursor composition comprising magnesium, titanium, and alkoxide moieties with a titanium halide compound and an internal electron donor in any order, in a suitable reaction medium to prepare a solid procatalyst composition, separating the solid procatalyst from the reaction medium, further exchanging residual alkoxide functionality of the solid procatalyst composition for chloride functionality by contacting the same two or more times with benzoyl chloride halogenating agent under metathesis conditions for a period of time sufficient to prepare a solid procatalyst composition having a decreased alkoxide content compared to the alkoxide content of the solid procatalyst composition before said exchange, and recovering the solid procatalyst composition.

1 . A process for polymerizing an olefin monomer comprising contacting the olefin monomer under polymerization conditions with a Ziegler-Natta olefin polymerization catalyst composition comprising a solid procatalyst composition, 
 a cocatalyst; and    a selectivity control agent,    wherein the solid procatalyst composition is prepared by    contacting a solid precursor composition comprising magnesium, titanium, and alkoxide moieties with a titanium halide compound and an internal electron donor in any order, in a suitable reaction medium to prepare a solid procatalyst composition,    separating the solid procatalyst composition from the reaction medium,    further exchanging residual alkoxide functionality of the solid procatalyst composition for chloride functionality by contacting the same two or more times with benzoyl chloride under metathesis conditions for a period of time sufficient to prepare a solid procatalyst composition having a decreased alkoxide content compared to the alkoxide content of the solid procatalyst composition before said exchange and without cooling of the procatalyst composition by greater than 25° C., and    recovering the solid procatalyst composition.    
     
     
         2 . A process according to  claim 1  wherein propylene or a mixture of propylene and ethylene is polymerized.  
     
     
         3  A process according to  claim 1  conducted in two or more gas-phase polymerization reactors operating in series wherein the polymer in an ethylene/propylene rubber modified polypropylene containing at least 40 weight percent rubber.