摘要:
A method of modifying a Ziegler-Natta type polyolefin catalyst comprises contacting the Ziegler-Natta catalyst with olefin monomer to form a prepolymerized catalyst. The prepolymerized catalyst can comprise a reduced number of catalyst particles having a size of 40 microns or less. The prepolymerized catalyst can be used in a polymerization process to produce polymer fluff particles with a reduced number of polymer fluff fines than the Ziegler-Natta type catalyst.
摘要:
A method of modifying a Ziegler-Natta type polyolefin catalyst comprises contacting the Ziegler-Natta catalyst with olefin monomer to form a prepolymerized catalyst. The prepolymerized catalyst can comprise a reduced number of catalyst particles having a size of 40 microns or less. The prepolymerized catalyst can be used in a polymerization process to produce polymer fluff particles with a reduced number of polymer fluff fines than the Ziegler-Natta type catalyst.
摘要:
A new synthesis of a Ziegler-Natta catalyst uses a multi-step preparation which includes treating a soluble magnesium compound with successively stronger chlorinating-titanating reagents. The catalyst may be used in polymerization of olefins, particularly ethylene, to produce a polymer with low amount of fines, large average fluff particle size and narrow molecular weight distribution. The catalyst has high activity and good hydrogen response.
摘要:
A process of forming a polyolefin catalyst component includes contacting a metal compound of the formula MR2 with a diketone to form a metal bis(diketonate) having the formula M(OCRCR′CRO)2, wherein M is a Group IIA or Group VIIB metal, and wherein R and R′ are each hydrocarbyls or substituted hydrocarbyls having from 1 to 20 carbons atoms. Catalyst components, catalysts, polyolefin polymers, catalysts systems, and methods of preparing same are disclosed.
摘要:
The present invention includes a bimodal polyethylene polymerization process wherein metallocene catalyst to is used to adjust the hydrogen response of a Ziegler-Natta catalyst. The polymerization may be carried out in a single reactor or in two or more reactors in series, preferably two or more continuously stirred tank reactors in series. In an embodiment having two or more reactors, the Zeigler-Natta catalyst is added to a first reactor and the metallocene catalyst is added to a downstream reactor. In another embodiment having two or more reactors, the Zeigler-Natta catalyst and metallocene catalyst are added to the same reactor, preferably an upstream reactor. A preferred Zeigler-Natta catalyst comprises TiCl4, and a preferred metallocene catalyst comprises bis(cyclopentadienyl) titanium dichloride.
摘要:
The present invention includes a bimodal polyethylene polymerization process wherein metallocene catalyst to is used to adjust the hydrogen response of a Ziegler-Natta catalyst. The polymerization may be carried out in a single reactor or in two or more reactors in series, preferably two or more continuously stirred tank reactors in series. In an embodiment having two or more reactors, the Zeigler-Natta catalyst is added to a first reactor and the metallocene catalyst is added to a downstream reactor. In another embodiment having two or more reactors, the Zeigler-Natta catalyst and metallocene catalyst are added to the same reactor, preferably an upstream reactor. A preferred Zeigler-Natta catalyst comprises TiCl4, and a preferred metallocene catalyst comprises bis(cyclopentadienyl) titanium dichloride.
摘要:
Processes for the formulation of Ziegler-type catalysts from a plurality of catalyst components including transition metal, organosilicon electron donor, and organoaluminum co-catalyst components. The components are mixed together in the course of formulating the Ziegler-type catalyst to be charged to an olefin polymerization reactor. Several orders of addition of the catalyst components can be used in formulating the Ziegler catalyst. One involves mixing of the transition metal component with the organoaluminum co-catalyst to formulate a mixture having an aluminum/transition metal mole ratio of at least 200. This mixture is combined with the organosilicon electron donor component to produce a Ziegler-type catalyst formulation having an aluminum/silicon mole ratio of no more than 50. There may be an initial pre-polymerization of the catalyst prior to introducing the catalyst into an olefin polymerization reactor. The mole ratio of aluminum to silicon in the catalyst formulation within the range of 20 to 50 and the mole ratio of silicon to transition metal within the range of 10-20. Relatively short time sequences can be used in formulating the Ziegler-type catalyst. Another order of addition involves initial contact of the organoaluminum co-catalyst and the organosilicon electron donor to provide a mixture having an aluminum to silicon mole ratio of at least 10. This mixture is then combined with the transition metal component having an aluminum/transition metal mole ratio of at least 200.
摘要:
Supported stereospecific catalysts and processes for the stereotactic propagation of a polymer chain derived from ethylenically unsaturated monomers which contain three or more carbon atoms or which are substituted vinyl compounds, such as styrene and vinyl chloride. One application is the stereospecific propagation of C3-C4 alpha olefins, particularly the polymerization of propylene to produce syndiotactic polypropylene over a supported metallocene catalyst comprising a stereospecific metallocene catalyst component incorporating a metallocene ligand structure having two sterically dissimilar cyclopentadienyl ring structures coordinated to the central transition metal atom. Both of the cyclopentadienyl groups are in a relationship with one another by virtue of bridge or substituent groups, which provide a stereorigid relationship relative to the coordinating transition metal atom to prevent rotation of said ring structures. The metallocene catalyst component and a co-catalyst component, an alumoxane or an alkyl aluminum, are supported on a particulate silica support comprising spheroidal silica particles having an average diameter within the range of 5-40 microns and an average effective pore size within the range of 50-350 angstroms. The particulate silica support contains at least 50 wt. % of the supported catalyst component within the pore volume of the silica support. The particles are preferably toroidal shaped, i.e. donut shaped.
摘要:
A polyolefin metallocene catalyst which includes two metallocene components, a stereorigid isospecific metallocene catalyst component and a stereorigid syndiospecific metallocene catalyst component, both of which are supported upon the same support. A method of forming a catalyst system includes contacting the above catalyst with a cocatalyst or Lewis acid. A method of polymerization includes contacting an olefin with the catalyst system.
摘要:
The invention provides a polymerization process with improved catalyst activity of a metallocene catalyst supported on silica treated with MAO, a process for supporting a metallocene compound on silica treated with MAO, a metallocene catalyst supported on silica treated with MAO within a certain temperature range and a process for making a metallocene catalyst supported on silica treated with MAO. The invention includes supporting the metallocene compound on a MAO-treated silica at a temperature of below 0° C. The supported catalyst is activated with an aluminum alkyl. The catalyst may be prepolymerized in a tubular reactor prior to being introduced into the polymerization reaction zone.