Back to results
US 2004/0167015 A1Published application
Production of broad molecular weight polyethylene
OwnerKevin J. Cann, Minghui Zhang +2inventors
InventorsKevin J. Cann, Minghui Zhang, John H. Moorhouse, Maria A. Apecetche
Life of this patent
Estimating the term…
Abstract
Broad molecular weight polyethylene and polyethylene having a bimodal molecular weight profile can be produced with chromium oxide based catalyst systems employing alkyl silanols. The systems may also comprise various organoaluminum compounds. Catalyst activity and molecular weight of the resulting polyethylene may also be tuned using the present invention.
Claims45
A supported chromium catalyst comprising:
- chromium oxide,
- a silica-containing support comprising silica selected from the group consisting of silica having:
- (a) a pore volume of about 1.1-1.8 cm3/g and a surface area of about 245-375 m2/g;
- (b) a pore volume of about 2.4-3.7 cm3/g and a surface area of about 410-620 m2/g;
- and
- (c) a pore volume of about 0.9-1.4 cm3/g and a surface area of about 390-590 m2/g;
- and,
- an alkyl silanol,
- wherein said supported chromium catalyst is activated at 400-860° C., prior to the addition of said alkyl silanol.
6 more elements
A supported chromium catalyst comprising:
- chromium oxide,
- a silica-containing support comprising silica selected from the group consisting of silica having:
- (a) a pore volume of about 1.1-1.8 cm3/g and a surface area of about 245-375 m2/g;
- (b) a pore volume of about 2.4-3.7 cm3/g and a surface area of about 410-620 m2/g;
- and
- (c) a pore volume of about 0.9-1.4 cm3/g and a surface area of about 390-590 m2/g;
- and,
- an organoaluminum compound,
- wherein said supported chromium catalyst is activated at 400-860° C.
6 more elements
A supported chromium catalyst comprising:
- chromium oxide,
- a silica-containing support comprising silica selected from the group consisting of silica having:
- (a) a pore volume of about 1.1-1.8 cm3/g and a surface area of about 245-375 m2/g;
- (b) a pore volume of about 2.4-3.7 cm3/g and a surface area of about 410-620 m2/g;
- and
- (c) a pore volume of about 0.9-1.4 cm3/g and a surface area of about 390-590 m2/g;
- wherein said supported chromium catalyst is activated at 400-860° C.;
- and,
- a second chromium-based compound comprising silylchromate on silica treated with an organoaluminum compound.
6 more elements
A process for producing an ethylene polymer comprising the steps of:
- contacting ethylene under polymerization conditions with a catalyst system, said catalyst system comprising chromium oxide, an alkyl silanol compound, and a silica-containing support comprising silica selected from the group consisting of silica having:
- (a) a pore volume of about 1.1-1.8 cm3/g and a surface area of about 245-375 m2/g;
- (b) a pore volume of about 2.4-3.7 cm3/g and a surface area of about 410-620 m2/g;
- and
- (c) a pore volume of about 0.9-1.4 cm3/g and a surface area of about 390-590 m2/g;
- and,
- controlling one or more of catalyst activity, polymer Mz/Mw, polymer Mw/Mn, and polymer density of the resulting ethylene polymer by varying the level of addition of said alkyl silanol.
4 more elements
A process for producing an ethylene polymer comprising the steps of:
- contacting ethylene under polymerization conditions with a catalyst system, said catalyst system comprising chromium oxide,
- a silica-containing support comprising silica selected from the group consisting of silica having:
- (a) a pore volume of about 1.1-1.8 cm3/g and a surface area of about 245-375 m2/g;
- (b) a pore volume of about 2.4-3.7 cm3/g and a surface area of about 410-620 m2/g, and
- (c) a pore volume of about 0.9-1.4 cm3/g and a surface area of about 390-590 m2/g;
- wherein said supported chromium catalyst is activated at 400-860° C.;
- and,
- a second chromium-based compound comprising silylchromate on silica treated with an organoaluminum compound;
- and,
- controlling one or more of polymer molecular weight, polymer Mz/Mw, polymer Mw/Mn, and distribution of comonomer incorporation by varying the relative amount of each of said chromium oxide and said second chromium-based compound.
7 more elements
Dependencies are inferred from the claim text.