Catalyst systems having both a metallocene catalyst component and a Ziegler-Natta component are disclosed. Such catalyst systems can contain a metallocene compound, an activator-support, an organoaluminum compound, and a Ziegler-Natta component comprising titanium supported on magnesium chloride.

Methods for preparing metallocene-based catalyst compositions include the steps of contacting an alcohol compound and an organoaluminum compound for a first period of time to form a precontacted mixture, and contacting the precontacted mixture with an activator-support and a metallocene compound for a second period of time to form the catalyst composition. Such catalyst compositions can contain an activator-support, a metallocene compound, an organoaluminum compound, and a dialkyl aluminum alkoxide, and these catalyst compositions have increased catalytic activity for the polymerization of olefins.

Disclosed herein are high melt flow polypropylene homopolymers generally characterized by a melt flow rate ranging from 200 g/10 min to 3000 g/10 min, a ratio of Mw/Mn ranging from 2 to 5, and a peak melting point ranging from 138 C. to 151 C. These polypropylene homopolymers can be produced by catalyst systems containing a racemic ansa-bis(indenyl)zirconocene compound, an activator-support, and an organoaluminum co-catalyst.

Disclosed herein are ethylene-based polymers generally characterized by a Mw ranging from 70,000 to 200,000 g/mol, a ratio of Mz/Mw ranging from 1.8 to 20, an IB parameter ranging from 0.92 to 1.05, and an ATREF profile characterized by one large peak. These polymers have the dart impact, tear strength, and optical properties of a metallocene-catalyzed LLDPE, but with improved processability, melt strength, and bubble stability, and can be used in blown film and other end-use applications.

In at least one embodiment, a catalyst compound is represented by Formula (I): ##STR00001## where M is a group 4 metal. Each of R.sup.1, R.sup.2, R.sup.3, R.sup.4, R.sup.5, R.sup.6, R.sup.7, R.sup.8, R.sup.9, R.sup.10, R.sup.11, R.sup.12, R.sup.13, and R.sup.14 is independently hydrogen, or a linear or branched C.sub.1-C.sub.50 substituted or unsubstituted hydrocarbyl, halocarbyl or silylcarbyl. At least one of R.sup.1 and R.sup.3 is not hydrogen. Each X is independently a halide or C.sub.1-C.sub.50 substituted or unsubstituted hydrocarbyl, hydride, amide, alkoxide, sulfide, phosphide, halide, diene, amine, phosphine, ether, or a combination thereof, or two Xs are joined together to form a metallocycle ring, or two Xs are joined to form a chelating ligand, a diene ligand, or an alkylidene.

Disclosed herein are high melt flow polypropylene homopolymers generally characterized by a melt flow rate ranging from 200 g/10 min to 3000 g/10 min, a ratio of Mw/Mn ranging from 2 to 5, and a peak melting point ranging from 138 C. to 151 C. These polypropylene homopolymers can be produced by catalyst systems containing a racemic ansa-bis(indenyl)zirconocene compound, an activator-support, and an organoaluminum co-catalyst.

Methods for preparing supported chromium catalysts containing a chromium (III) compound and an activator-support are disclosed. These supported chromium catalysts can be used in catalyst compositions for the polymerization of olefins to produce polymers having low levels of long chain branching, and with greater sensitivity to the presence of hydrogen during polymerization.

Disclosed herein are ethylene-based polymers generally characterized by a melt index of less than 1 g/10 min, a density from 0.93 to 0.965 g/cm.sup.3, a CY-a parameter at 190 C. of less than 0.2, an average number of short chain branches per 1000 total carbon atoms of the polymer in a molecular weight range of 400,000 to 600,000 g/mol that is greater than that in a molecular weight range of 40,000 to 60,000 g/mol, and an average number of long chain branches per 1000 total carbon atoms of the polymer in a molecular weight range of 400,000 to 600,000 g/mol that is greater than that in a molecular weight range of 4,000,000 to 6,000,000 g/mol. The ethylene polymers can be used to fabricate pipes, blown films, and blow molded products, and the ethylene polymers can be produced with a dual catalyst system containing a single atom bridged or two carbon atom bridged metallocene compound with two indenyl groups or an indenyl group and a cyclopentadienyl group, and a single atom bridged metallocene compound with a fluorenyl group and a cyclopentadienyl group with an alkenyl substituent.

A method comprising a) contacting a solvent, a carboxylic acid, and a peroxide-containing compound to form an acidic mixture wherein a weight ratio of solvent to carboxylic acid in the acidic mixture is from about 1:1 to about 100:1; b) contacting a titanium-containing compound and the acidic mixture to form a solubilized titanium mixture wherein an equivalent molar ratio of titanium-containing compound to carboxylic acid in the solubilized titanium mixture is from about 1:1 to about 1:4 and an equivalent molar ratio of titanium-containing compound to peroxide-containing compound in the solubilized titanium mixture is from about 1:1 to about 1:20; and c) contacting a chromium-silica support comprising from about 0.1 wt. % to about 20 wt. % water and the solubilized titanium mixture to form an addition product and drying the addition product by heating to a temperature in a range of from about 50 C. to about 150 C. and maintaining the temperature in the range of from about 50 C. to about 150 C. for a time period of from about 30 minutes to about 6 hours to form a pre-catalyst.

A method of monitoring a solid component of a reactor feed stream in a polymer production system, comprising (a) measuring a turbidity of the reactor feed stream, wherein the reactor feed stream comprises a solid component of a polymerization catalyst system, and (b) translating the turbidity of the reactor feed stream into a concentration of the solid component in the reactor feed stream. A method of monitoring a solid component of a reactor feed stream in a polymer production system, comprising (a) measuring a turbidity of a precontactor feed stream, wherein the precontactor feed stream comprises a solid component of a polymerization catalyst system, and (b) translating the turbidity of the precontactor feed stream into a concentration of the solid component in a precontactor effluent stream, wherein the precontactor effluent stream comprises the reactor feed stream.