Indazole-modified ziegler-natta catalyst system
A modified Ziegler-Natta catalyst system, a method for preparing the catalyst system, and a process for polymerizing an olefin in the presence of the catalyst system are disclosed. The catalyst system comprises a titanium or vanadium compound, an aluminum compound, and an indazole. Improved comonomer incorporation and the ability to regulate molecular weight are achieved in the manufacture of polyolefins.
1 - 10 . (canceled)
11 . A process for making polyethylene, comprising polymerizing ethylene and an α-olefin comonomer selected from the group consisting of 1-butene, 1-hexene, and 1-octene in the presence of a modified Ziegler-Natta catalyst system, wherein the catalyst system comprises: (a) a titanium or vanadium compound; (b) an aluminum compound selected from the group consisting of trialkyl aluminums, dialkyl aluminum halides, alkyl aluminum dihalides, and combinations thereof; and (c) an indazole;
wherein comonomer incorporation in the polyethylene is increased compared with that of a polyethylene produced using the catalyst system without the indazole compound.
12 . The process of claim 11 wherein the titanium or vanadium compound is selected from the group consisting of titanium halides, titanium alkoxides, vanadium halides, vanadium oxyhalides, vanadium alkoxides, and combinations thereof.
13 . The process of claim 11 wherein the indazole has the structure:
wherein each R is independently H, Cl, Br, or C 1 -C 16 hydrocarbyl.
14 . The process of claim 13 wherein each R is H.
15 . The process of claim 11 wherein the molar ratio of indazole to titanium is from 1:1 to 50:1.
16 . The process of claim 11 wherein the catalyst system is prepared by a method comprising: (a) reacting an indazole with an aluminum compound selected from the group consisting of trialkyl aluminums, dialkyl aluminum halides, alkyl aluminum dihalides, and combinations thereof; and (b) contacting the reaction mixture from step (a) with a titanium or vanadium compound.