摘要:
The invention provides a process for commercial production of syndiotactic polyolefins using a metallocene catalyst supported on silica treated with MAO. The invention includes contacting the supported metallocene catalyst with an aluminum alkyl and aging the catalyst prior to polymerization. In addition, the catalyst is prepolymerized in a tubular reactor prior to being introduced into the polymerization reaction zone. The treated silica is produced by removing water to a level of 0.5-1.08%, slurrying in a nonpolar solvent, adding an alumoxane, heating to reflux, cooling the slurry, and separating the solid product.
摘要:
The invention provides a process for commercial production of syndiotactic polyolefins using a metallocene catalyst supported on silica treated with MAO. The invention includes contacting the supported metallocene catalyst with a trialkylaluminum and aging the catalyst 12 to 24 hours prior to polymerization.
摘要:
The invention provides a process for commercial production of syndiotactic polyolefins using a metallocene catalyst supported on silica treated with MAO. The invention includes contacting the supported metallocene catalyst with an aluminum alkyl and aging the catalyst prior to polymerization. In addition, the catalyst is prepolymerized in a tubular reactor prior to being introduced into the polymerization reaction zone.
摘要:
A method of forming a polyolefin catalyst component which includes chlorinating a magnesium alkoxide, solubilizing the chlorinated magnesium alkoxide into a hydrocarbon solvent utilizing an alcohol, and then precipitating a solid from the solvent by the dropwise addition of titanium tetrachloride. Two more titanation steps follow, the first with an electron donor, the second without an electron donor, to produce a catalyst having an improved yield of polymer.
摘要:
This invention relates to a conventional supported heterogeneous Ziegler-Natta catalyst for the polymerization of olefins. It has been found that adding a lithium compound to a transition metal catalyst component and then adding an organoaluminum co-catalyst and an organosilicon electron donor produces a catalyst which yields polymer with increased molecular weight. The lithium compound is of the general formula LiCp wherein Cp is a cyclopentadienyl or substituted cyclopentadienyl and is preferably lithium cyclopentadienide or lithium indene. Preferably, the molar ratio of lithium compound/transition metal is at least 0.2.
摘要:
This invention relates to a process for making a catalyst in which a metallocene is included in the synthesis of a Ziegler-Natta catalyst and a process for using the catalyst in the polymerization of olefins, specifically, propylene, to produce a polymer product with broad polydisperisty. The catalyst may be synthesized by: 1) selecting a solid component comprising a magnesium dialkoxide; 2) adding a chlorinating agent; 3) adding a titanating agent; 4) adding a metallocene prior to step 2), after step 2), prior to step 3) or after step 3) and 5) adding an aluminum alkyl cocatalyst.
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:
Processes for the formulation of Ziegler-type catalysts from a transition metal component, an electron donor and a co-catalyst which are sequentially mixed together. The co-catalyst is initially contacted with either of the transition metal catalyst or the electron donor for a first contact time of 5-120 seconds. This mixture is then contacted with the remainder of the electron donor or transition metal component for a second contact time of less and 110 seconds. The three component system is then used in olefin polymerization. The olefin contacting step can involve an initial pre-polymerization reaction. A specific order of addition involves mixture of the transition metal component and the co-catalyst component for a contact time of 5-120 seconds followed by contact with an electron donor component for no more than 30 seconds. Another order of addition involves initially contacting the electron donor with the co-catalyst. A further order of addition is such that the electron donor is initially contacted with the transition metal component for up to 40 seconds. The resulting mixture is then contacted with the co-catalyst component for a shorter second contact time up to 20 seconds.
摘要:
An olefin polymerization process in which at least two introductions of hydrogen are made during the olefin polymerization reaction. Suitable catalysts include metallocenes of the general formula (Cp).sub.m TiX.sub.n, wherein Cp is a substituted or unsubstituted cyclopentadienyl ring, X is a halogen, m=1-2, n=2-3, and wherein m+n=4, and conventional Ziegler-Natta catalysts blended with or modified by such metallocenes.
摘要:
This invention concerns a catalyst system comprising at least one homogeneous catalyst and at least one heterogeneous catalyst, specifically, a metallocene catalyst and a conventional Ziegler-Natta catalyst, respectively. This invention is useful in the polymerization of any polymer in which separate polymerizations with a homogeneous catalyst and with a heterogeneous catalyst are possible, but preferably, polymerization of olefins, more preferably, .alpha.-olefins, and, most preferably, propylene. This invention provides a catalyst system which facilitates use of a homogeneous catalyst but eliminates the disadvantages of such a system. This invention produces a polymer with molecular weight distribution (MWD) as broad or broader than the MWD of the heterogeneous catalyst alone. Hydrogen can be used to control molecular weight distribution of a polymer produced with this invention.