Methods of catalyst activation

Abstract

A method comprising preparing a multi-component catalyst system comprising a catalyst and a cocatalyst, and adjusting the level of at least one component of the catalyst system to maintain a user-desired level of catalyst activity throughout a process, wherein the component comprises a catalyst activator and wherein the catalyst activator comprises the catalyst or the cocatalyst. A method comprising contacting a polymerization catalyst system comprising a Ziegler-Natta catalyst and a cocatalyst with a catalyst activator at least twice during a polymerization process, wherein the polymerization process is carried out in a reactor system comprising multiple reactor types.

1 . A method comprising:
 preparing a multi-component catalyst system comprising a catalyst and a cocatalyst; and adjusting the level of at least one component of the catalyst system to maintain a user-desired level of catalyst activity throughout a process; wherein the component comprises a catalyst activator and   wherein the catalyst activator comprises the catalyst or the cocatalyst.   
     
     
         2 . The method of  claim 1  wherein the catalyst activator functions to maintain the catalyst system activity to a user-desired threshold level throughout a process. 
     
     
         3 . The method of  claim 1  wherein the catalyst system further comprises an electron donor. 
     
     
         4 . The method of  claim 1  wherein catalyst activator consists essentially of one of the catalyst, the cocatalyst, or an electron donor. 
     
     
         5 . The method of  claim 1  wherein the catalyst comprises a Ziegler-Natta catalyst, a metallocene catalyst, or combinations thereof. 
     
     
         6 . The method of  claim 1  wherein the cocatalyst comprises an organoaluminum compound. 
     
     
         7 . The method of  claim 6  wherein the organoaluminum compound comprises triethylaluminum, tri-isobutylaluminum, diethylaluminum chloride, diethylaluminum hydride, methylalumoxane, tri-isobutylaluminum, or combinations thereof. 
     
     
         8 . The method of  claim 3  wherein the electron donor comprises an external electron donor. 
     
     
         9 . The method of  claim 8  wherein the external electron donor comprises cyclohexylmethyl dimethoxysilane, dicyclopentyl dimethoxysilane, diisopropyl dimethoxysilane, or combinations thereof. 
     
     
         10 . The method of  claim 1  wherein catalyst system functions as a polymerization catalyst. 
     
     
         11 . The method of  claim 1  wherein the catalyst system is introduced to a first location in a reaction zone and the catalyst activator is introduced to a second location in the reaction zone. 
     
     
         12 . The method of  claim 11  wherein the reaction zone comprises multiple reactor types. 
     
     
         13 . A method comprising contacting a polymerization catalyst system comprising a Ziegler-Natta catalyst and a cocatalyst with a catalyst activator at least twice during a polymerization process, wherein the polymerization process is carried out in a reactor system comprising multiple reactor types. 
     
     
         14 . The method of  claim 13  wherein the reactor system comprises a prepolymerization reactor and a bulk loop reactor disposed upstream of the gas phase reactor. 
     
     
         15 . The method of  claim 13  wherein the catalyst activator is introduced to the prepolymerization reactor, to the gas phase reactor, or combinations thereof. 
     
     
         16 . The method of  claim 13  wherein the catalyst activator is introduced to the reactor system downstream of the prepolymerization reactor and upstream of the gas phase reactor. 
     
     
         17 . The method of  claim 13  wherein the polymerization process comprises contacting a monomer and a comonomer with the polymerization catalyst system to produce an impact copolymer. 
     
     
         18 . The method of  claim 17  wherein the monomer comprises propylene and the comonomer comprises ethylene. 
     
     
         19 . The method of  claim 13  wherein the polymerization catalyst system comprises a Ziegler-Natta catalyst. 
     
     
         20 . The method of  claim 13  wherein the polymerization catalyst system comprises a cocatalyst. 
     
     
         21 . The method of  claim 20  wherein the cocatalyst comprises triethylaluminum, tri-isobutylaluminum, diethylaluminum chloride, diethylaluminum hydride, methylalumoxane, tri-isobutylaluminum, isoprenylaluminum, or combinations thereof. 
     
     
         22 . The method of  claim 1  wherein the catalyst activator and the cocatalyst are the same compound. 
     
     
         23 . The method of  claim 22  wherein the amount of catalyst activator is equal to x+y wherein x is the amount of cocatalyst normally present in the polymerization process and y is greater than zero. 
     
     
         24 . The method of  claim 13  wherein the polymer yield is increased by greater than 5% when compared to an otherwise similar process lacking the introduction of a catalyst activator during the process. 
     
     
         25 . The method of  claim 13  wherein a process efficiency is increased by greater than 5% when compared to an otherwise similar process lacking the introduction of a catalyst activator during the process. 
     
     
         26 . A method comprising contacting a propylene monomer and ethylene comonomer with a catalyst system in a reactor system comprising a loop reactor disposed upstream of a gas phase reactor under conditions suitable to produce a polypropylene impact copolymer; wherein a catalyst activator is introduced to the reactor system upstream of the gas phase reactor.