Supported chromium catalysts containing a solid oxide and 0.1 to 15 wt. % chromium, in which the solid oxide or the supported chromium catalyst has a particle size span from 0.5 to 1.4, less than 3 wt. % has a particle size greater than 100 μm, and less than 10 wt. % has a particle size less than 10 μm, can be contacted with an olefin monomer in a loop slurry reactor to produce an olefin polymer. Representative ethylene-based polymers produced using the chromium catalysts have a HLMI of 4 to 70 g/10 min, a density from 0.93 to 0.96 g/cm.sup.3, from 150 to 680 ppm solid oxide (such as silica), from 1.5 to 6.8 ppm chromium, and a film gel count of less than 15 catalyst particle gels per ft.sup.2 of 25 micron thick film and/or a gel count of less than or equal to 50 catalyst particles of greater than 100 μm per five grams of the ethylene polymer.

Processes for producing an activated chromium catalyst are disclosed, and these processes comprise contacting a supported chromium catalyst with a gas stream containing from 25-60 vol % oxygen at a peak activation temperature of 550-900° C. to produce the activated chromium catalyst. The linear velocity of the gas stream is 0.18-0.4 ft/sec, and the oxygen linear velocity of the gas stream is 0.05-0.15 ft/sec. The resultant activated chromium catalyst and an optional co-catalyst can be contacted with an olefin monomer and an optional olefin comonomer in a polymerization reactor system under polymerization conditions to produce an olefin polymer.

Processes for producing an activated chromium catalyst are disclosed, and these processes comprise contacting a supported chromium catalyst with a gas stream containing from 25-60 vol % oxygen at a peak activation temperature of 550-900° C. to produce the activated chromium catalyst. The linear velocity of the gas stream is 0.18-0.4 ft/sec, and the oxygen linear velocity of the gas stream is 0.05-0.15 ft/sec. The resultant activated chromium catalyst and an optional co-catalyst can be contacted with an olefin monomer and an optional olefin comonomer in a polymerization reactor system under polymerization conditions to produce an olefin polymer.

A unimodal ethylene-co-1-hexene copolymer that, when in melted form at 190 degrees Celsius, is characterized by a unique melt property space defined by combination of melt elasticity and complex viscosity ratio (shear thinning)properties. A blown film consisting essentially of the unimodal ethylene-co-1-hexene copolymer. A method of synthesizing the unimodal ethylene-co-1-hexene copolymer. A method of making the blown film. A manufactured article comprising the unimodal ethylene-co-1-hexene copolymer.

A unimodal ethylene-co-1-hexene copolymer that, when in melted form at 190 degrees Celsius, is characterized by a unique melt property space defined by combination of melt elasticity and complex viscosity ratio (shear thinning)properties. A blown film consisting essentially of the unimodal ethylene-co-1-hexene copolymer. A method of synthesizing the unimodal ethylene-co-1-hexene copolymer. A method of making the blown film. A manufactured article comprising the unimodal ethylene-co-1-hexene copolymer.

A method of operating a polyethylene reactor system includes feeding ethylene, an optional first comonomer, a diluent, and a chromium-based catalyst to a first polymerization reactor. The method further includes contacting ethylene and the comonomer with the catalyst in the first polymerization reactor to form a first product including a first polyethylene. The method further includes feeding the first product from the first polymerization reactor to a second polymerization reactor. The method further includes contacting ethylene and a second optional comonomer with catalyst from the first reactor in the second polymerization reactor to form a second product including the first polyethylene and a second polyethylene. The method further includes controlling one or both of a molecular weight or a breadth of molecular weight distribution of the second product by adjusting a rate of hydrogen fed to one or both of the first polymerization reactor or the second polymerization reactor.

A method of operating a polyethylene reactor system includes feeding ethylene, an optional first comonomer, a diluent, and a chromium-based catalyst to a first polymerization reactor. The method further includes contacting ethylene and the comonomer with the catalyst in the first polymerization reactor to form a first product including a first polyethylene. The method further includes feeding the first product from the first polymerization reactor to a second polymerization reactor. The method further includes contacting ethylene and a second optional comonomer with catalyst from the first reactor in the second polymerization reactor to form a second product including the first polyethylene and a second polyethylene. The method further includes controlling one or both of a molecular weight or a breadth of molecular weight distribution of the second product by adjusting a rate of hydrogen fed to one or both of the first polymerization reactor or the second polymerization reactor.

Supported chromium catalysts with an average valence less than +6 and having a hydrocarbon-containing or halogenated hydrocarbon-containing ligand attached to at least one bonding site on the chromium are disclosed, as well as ethylene-based polymers with terminal alkane, aromatic, or halogenated hydrocarbon chain ends. Another ethylene polymer characterized by at least 2 wt. % of the polymer having a molecular weight greater than 1,000,000 g/mol and at least 1.5 wt. % of the polymer having a molecular weight less than 1000 g/mol is provided, as well as an ethylene homopolymer with at least 3.5 methyl short chain branches and less than 0.6 butyl short chain branches per 1000 total carbon atoms.

Supported chromium catalysts with an average valence less than +6 and having a hydrocarbon-containing or halogenated hydrocarbon-containing ligand attached to at least one bonding site on the chromium are disclosed, as well as ethylene-based polymers with terminal alkane, aromatic, or halogenated hydrocarbon chain ends. Another ethylene polymer characterized by at least 2 wt. % of the polymer having a molecular weight greater than 1,000,000 g/mol and at least 1.5 wt. % of the polymer having a molecular weight less than 1000 g/mol is provided, as well as an ethylene homopolymer with at least 3.5 methyl short chain branches and less than 0.6 butyl short chain branches per 1000 total carbon atoms.

Supported chromium catalysts containing a solid oxide and 0.1 to 15 wt. % chromium, in which the solid oxide or the supported chromium catalyst has a particle size span from 0.5 to 1.4, less than 3 wt. % has a particle size greater than 100 μm, and less than 10 wt. % has a particle size less than 10 μm, can be contacted with an olefin monomer in a loop slurry reactor to produce an olefin polymer. Representative ethylene-based polymers produced using the chromium catalysts have a HLMI of 4 to 70 g/10 min, a density from 0.93 to 0.96 g/cm.sup.3, from 150 to 680 ppm solid oxide (such as silica), from 1.5 to 6.8 ppm chromium, and a film gel count of less than 15 catalyst particle gels per ft.sup.2 of 25 micron thick film and/or a gel count of less than or equal to 50 catalyst particles of greater than 100 μm per five grams of the ethylene polymer.