Process for controlling the MWD of a broad/bimodal resin in a single reactor

Abstract

A make-up catalyst of at least one metallic component of a bimetallic catalyst component is used in conjunction with a bimetallic catalyst to control the proportion of weight fractions in broad or bimodal molecular weight distribution olefin resin product. The bimetallic catalyst produces broad or bimodal molecular weight distribution polyolefin resin whose composition depends on the ratio of the concentration of the two catalyst components producing the HMW/LMW components. The make-up catalyst consisting of a single metal component is added in proportion necessary to make-up the deficiencies in the amount of the HMW/LMW component. The type of make-up catalyst added depends on whether increase of the HMW or LMW component produced by te bimetallic catalyst is sought.

What is claimed is:  
     
         1 . A process for producing product, in a single reactor, wherein said product comprises ethylene polymers or copolymers of ethylene with one or more C 3 -C 10  alpha-olefins, wherein said product is characterized by broad or bimodal molecular weight distribution, wherein the process comprises: 
 contacting a feed selected from the group consisting of ethylene, C 3 -C 10  alpha-olefins, and admixtures thereof, with catalyst A) and catalyst B), under olefin polymerization conditions;    the catalyst A) comprises a supported catalyst which is formed from at least two different transition metal compounds of different hydrogen responses,    wherein a) one of said at least two different transition metal compounds provides, under olefin polymerization conditions, a polymerization product of relatively high molecular weight, and    wherein b) a second of said at least two different transition metal compounds, under identical polymerization conditions, provides a second polymerization product of lower molecular weight relative to said product of relatively high molecular weight;    wherein at least one of a) and b) is provided as a metallocene of a transition metal selected from the group consisting of Zr and Hf; and    cofeeding the catalyst B) in the presence of the catalyst A);    the catalyst B) comprises a support matrix formed from only one of said at least two transition metal compounds a) and b) so that catalyst B) comprises only a single transition metal component, so that: 
 when catalyst B) comprises said a) as the single transition metal component, the cofeeding of said catalyst B) results in an increase in said polymerization product of said relatively high molecular weight, and  
 wherein, when B) comprises said b) as the single transition metal component, the cofeeding of said second catalyst B) results in an increase in said polymerization product of said lower molecular weight; and  
 recovering said product.  
   
     
     
         2 . The process of  claim 1 , wherein a mixed catalyst system comprising catalyst A) and catalyst B) is formed, wherein the mixed catalyst system comprises greater than 50 weight percent of catalyst A).  
     
     
         3 . The process of  claim 2 , wherein catalyst A) comprises: 
 an aluminum alkyl non-oxygen containing cocatalyst, and    a dry, anhydrous, support containing composition comprising an activated metallocene compound of a transition metal and a non-metallocene transition metal,    wherein said aluminum alkyl cocatalyst activates said non-metallocene transition metal;    wherein the support is the reaction product of (1) silica having OH groups,, impregnated with R m MgR′ n , wherein each of R and R′ is alkyl of 4 to 10 carbon atoms,    wherein R m MgR′ n  is present in an amount to provide a R m MgR′ n :OH molar ratio of 0.5:1 to 4:1;    and (2) an organic alcohol reagent providing alkoxy groups having a formula R′O—, wherein R″ is an alkyl of 1 to 12 carbons; said alkoxy groups being effective to displace R and R′ of said R m MgR′ n , and    wherein said reagent is used in an amount effective to provide an alcohol/Mg molar ratio of 0.5 to 2.0.    
     
     
         4 . The process of  claim 3 , wherein each of R and R′ is alkyl of 4 to 8 carbon atoms.  
     
     
         5 . The process of  claim 3 , wherein each of R and R′ is butyl.  
     
     
         6 . The process of  claim 3 , wherein each of R and R′ contains 4 carbon atoms.  
     
     
         7 . The process of  claim 3 , wherein R″ is an alkyl of 2 to 8 carbons.  
     
     
         8 . The process of  claim 3 , wherein R″O— is provided as an alcohol.  
     
     
         9 . The process of  claim 3 , wherein the reaction product is formed by 
 (i) providing a slurry of a non-polar solvent and a solid porous silica having —OH groups;    (ii) impregnating said silica, with R m MgR′ n , to form an intermediate (ii), wherein the Mg:—OH groups ratio is less than 2, wherein each of said R and R′ is alkyl of 4 to 10 carbon atoms and is the same or different, wherein said R m MgR′ n , is soluble in said non-polar solvent;    (iii) treating the intermediate (ii) with an amount of R″OH, which amount is effective to provide a R″OH:R m MgR n  molar ratio of 0.5 to 2.0 to form a product.    
     
     
         10 . The process of  claim 9 , wherein the non-metallocene transition metal is titanium.  
     
     
         11 . The process of  claim 10 , wherein the non-metallocene transition metal comprises a non-metallocene transition metal compound of titanium tetrachloride.  
     
     
         12 . The process of  claim 11 , which further includes, after (iii), (vi) treating the product of (iii) with TiCl 4  to form a titanium containing intermediate; and 
 (v) combining the titanium containing intermediate with said cocatalyst.    
     
     
         13 . The process of  claim 12 , wherein the cocatalyst is trimethylaluminum.  
     
     
         14 . The process of  claim 3 , wherein the metallocene transition metal is provided as a compound which has the formula Cp x MA y B z , wherein Cp is cyclopentadienyl unsubstituted or substituted by alkyl of 1 to 6 carbon atoms; x is at least 1; each of A and B is halogen or alkyl of 1 to 8 carbon atoms, and y plus z is 3 or less provided that x+y+z is equal to the valence of M, which is selected from the group consisting of titanium, zirconium and hafnium.  
     
     
         15 . The process of  claim 3 , wherein the metallocene transition metal is provided as a compound which has the formula Cp x MA y B z , wherein Cp is cyclopentadienyl unsubstituted or substituted by alkyl or alkylene of 1 to 6 carbon atoms; x is at least 1; each of A and B is halogen or alkyl of 1 to 8 carbon atoms, and y plus z is 3 or less provided that x+y+z is equal to the valence of M, which is selected from the group consisting of titanium, zirconium and hafnium.  
     
     
         16 . The process of  claim 15 , wherein the metallocene compound is selected from the group consisting of bis(cyclopentadienyl) zirconium dichloride and bis(n butylcyclopentadienyl) zirconium dichloride.  
     
     
         17 . The process of  claim 15 , wherein the metallocene compound is activated with a solution of methylalumoxane; wherein the silica has a pore volume in the range of 1.0 cm 3 /g to 4.0 cm 3 /g; wherein the solution has a volume which is equal to the 5 total pore volume.  
     
     
         18 . The process of  claim 3 , wherein catalyst B) is in the form of particles wherein said particles have a particle size in the range of 1 to 500 μm. 
 wherein said particles comprise silica, a transition metal and aluminum, wherein the ratio of aluminum to transition metal ranges from about 70 to 350; wherein said silica is amorphous and porous and has a pore volume of 0.1 to 3.5 cm 3 /g; wherein said silica has a concentration of silanol groups wherein the concentration of silanol groups is at least 0.7 mmol per gram of silica;  
 wherein a solution of a mixture comprising bis(n-butylcyclopentadienyl) zirconium dichloride and alumoxane, provides said transition metal and said aluminum; wherein said solution has a maximum volume equal to the total pore volume of said silica, and wherein said solution is employed to impregnate said silica having said concentration of silanol groups.  
 
     
     
         19 . The process of  claim 18 , wherein said alumoxane has a formula (a) or (b), wherein: 
 (a) is R—(Al(R)—O) n —AlR 2  for oligomeric, linear alumoxanes, and    (b) is (—Al(R)—O—) m  for oligomeric cyclic alumoxane, wherein: 
 n is 1-40,  
 m is 3-40, and  
 R comprises a C 1 -C 8  alkyl group.  
   
     
     
         20 . The process of  claim 18 , wherein the alumoxane is methylalumoxane (MAO).  
     
     
         21 . The process of  claim 19 , wherein said mixture provides an Al:Zr mole ratio of 100 to 350.  
     
     
         22 . The process of  claim 21 , wherein said mixture provides an Al-Zr mole ratio of 100 to 200.  
     
     
         23 . The process of  claim 19 , wherein the particles are characterized by a particle size ranging from 1 to 250 μm.  
     
     
         24 . The process of  claim 18 , wherein the concentration of silanol groups is greater than 0.7 and up to about 2.5 mmol per gram of silica.  
     
     
         25 . The process of  claim 18 , wherein the concentration of silanol groups is from about 1.7 and up to about 1.9 mmol per gram of silica.  
     
     
         26 . The process of  claim 18 , wherein said mixture provides an Al:Zr ratio (elemental basis) of 100 to 200.  
     
     
         27 . The process of  claim 3 , wherein catalyst B) is in the form of particles wherein said particles have a particle size in the range of 1 to 500 μm 
 wherein said particles comprise silica, a transition metal and aluminum, wherein the ratio of aluminum to transition metal ranges from about 70 to 350;  
 wherein said silica is amorphous and porous and has a pore volume of 0.1 to 3.5 cm 3 /gm; wherein said silica has a concentration of silanol groups wherein the concentration of silanol groups is at least 0.7 mmol per gram of silica;  
 wherein a solution of a mixture of (tetrahydroindenyl) zirconium dichloride and aluminoxane, provides said transition metal and said aluminum;  
 wherein the solution has a maximum volume equal to the total pore volume of said silica, and wherein said solution is employed to impregnate said silica having said concentration of silanol groups.  
 
     
     
         28 . The process of  claim 27 , wherein said alumoxane has a formula (a) or (b), wherein: 
 (a) is R—(Al(R) —O) n —AlR 2  for oligomeric, linear alumoxanes, and    (b) is (—Al(R)—O—) m  for oligomeric cyclic alumoxane, wherein: 
 n is 1-40,  
 m is 3-40, and  
 R comprises a C 1 -C 8  alkyl group.  
   
     
     
         29 . The process of  claim 27 , wherein the alumoxane is methylalumoxane (MAO).  
     
     
         30 . The process of  claim 28 , wherein said mixture provides an Al:Zr mole ratio of 100 to 350.  
     
     
         31 . The process of  claim 30 , wherein said mixture provides an Al:Zr mole ratio of 100 to 200.  
     
     
         32 . The process of  claim 28 , wherein the particles are characterized by a particle size ranging from 1 to 250 μm.  
     
     
         33 . The process of  claim 27 , wherein the concentration of silanol groups is greater than 0.7 and up to about 2.5 mmol per gram of silica.  
     
     
         34 . The process of  claim 27 , wherein the concentration of silanol groups is from about 1.7 and up to about 1.9 mmol per gram of silica.  
     
     
         35 . The process of  claim 27 , wherein said mixture provides an Al:Zr ratio (elemental basis) of 100. to 200.  
     
     
         36 . The process of  claim 2 , wherein said at least two different transition metal compounds include Zr and Ti, and said catalyst A) includes Zr and Ti, and said catalyst B) includes Zr.  
     
     
         37 . The process of  claim 2 , wherein said catalyst B) provides monomodal polymer component in an amount comprising 1 to 30 weight percent of the product.