Selectivity in propene polymerization with metallocene catalysts.

Precise control of polyolefin stereochemistry using single-site metal catalysts.

Components of bimetallic catalysts for the polymerization of olefins comprising a compound of a transition metal M selected from Ti, V, Zr and Hf containing at least one M-π bond, a compound of Ti or V not containing metal-π bonds and a support comprising a magnesium halide. The catalysts obtained from the components of the invention are particularly suitable for gas-phase polymerization processes.

Components and catalysts for the polymerization of olefins

Ionic catalyst compositions can be prepared by combining two components. The first component is a bis(cyclopentadienyl) Group IV-B metal complex containing at least one ligand which will combine irreversibly with the second component or at least a portion thereof such as a cation portion thereof. The second component comprises a cation which will irreversibly react with at least one ligand on the Group IV-B metal complex and a non-coordinating anion. The combination of the two components produces an ionic catalyst composition comprising a cationic bis(cyclopentadienyl) Group IV-B metal complex which has a formal coordination number of 3 and a 4+ valence charge and the aforementioned non-coordinating anion. The anion is (i) labile and can be displaced by an olefin, diolefin or acetylenically unsaturated monomer; (ii) has a molecular diameter about or greater than 4 angstroms; (iii) forms stable salts with reducible Lewis acids and protonated Lewis bases; (v) has a negative charge delocalized over the framework on the anion or within the core thereof; (v) is not a reducing or oxidizing agent; and (vi) is a relatively poor nucleophile. These ionic catalyst compositions can be used to polymerize α-olefins, diolefins and/or acetylenically unsaturated monomers, either alone or in combination, to polymers and copolymers.

Ionic metallocene catalyst compositions

This invention relates to catalyst systems, and a method for using such system, for the enhanced production of homo and copolymer products of olefin, diolefin and/or acetylenically unsaturated monomers. This invention catalyst system comprises a Group III-A element compound for improving the productivity of an olefin polymerization catalyst which is the reaction product of a metallocene of a Group IV-B transition metal and an ionic activator compound comprising a cation capable of donating a proton and an anion which is bulky, labile and noncoordinateable with the Group IV transition metal cation produced upon reaction of the metallocene and activator compound to form the catalyst component of the catalyst system.

Catalyst system of enhanced productivity

This invention uses a new method of producing ionic metallocene compounds. These compounds are useful as catalysts for polymerization of olefins, primarily propylene. This method uses an ionizing agent which ionizes the neutral metallocene compound. The ionizing ionic compound does not contain an active proton and contains a carbonium, oxonium or sulfonium cation. The anion of the ionizing ionic compound is not coordinated or is only loosely coordinated to the metallocene cation and is chemically unreactive with the metallocene cation. Examples of such compounds are triphenylcarbenium tetrakis(pentafluorophenyl)boronate, triphenylcarbenium tris(pentafluorophenyl)phenyl boronate and triphenylcarbeniumtris(pentafluorophenyl)4-trimethylsilyl-2,3,5,6-tetrafluorophenylboronate. The process of making catalysts with this invention produces catalysts having high activity and does not produce by-products which can inhibit catalyst activity. This new synthesis is a clean reaction which does not produce a Lewis base. The process generates active catalysts by removing a methyl anion from a group IVB metallocene derivative.

Preparation of metallocene catalysts for polymerization of olefins

This invention is for a catalyst system comprising a neutral metallocene compound, an aluminum alkyl and a Lewis acid. The Lewis acid must be of sufficient acidity to ionize a neutral metallocene compound to form a cationic metallocene catalyst. The ligands of the Lewis acid should not be reactive with the metallocene cation. Any metallocene catalyst compound having two cyclopentadienyl rings, substituted or unsubstituted, attached to a transition metal which can be ionized by a Lewis acid would be useful in this invention. The invention is also for the process of making the catalyst system and the process for using the catalyst system in polymerization of olefins. The metallocene is contacted with the Lewis acid. The aluminum alkyl is contacted with the olefin. The two mixtures are contacted with each other under polymerization conditions.

Metallocene catalysts with Lewis acids and aluminum alkyls

This invention is for a metallocene catalyst component useful in preparing isotactic polyolefins, a catalyst system using this component and a process for polymerizing olefins using the catalyst component. The catalyst component consists of a bridged metallocene in which one of the cyclopentadienyl rings is substituted in a different manner from the other ring. One of the cyclopentadienyl ligands contains a bulky group in one and only one distal position and the other cyclopentadienyl ligand has bilateral or pseudobilateral symmetry. There is a steric difference between the two Cp rings. The catalyst component is a stereorigid metallocene described by the formula: R" (CpR.sub.n)(CpR'.sub.m)MeQ.sub.k wherein each Cp is a cyclopentadienyl or substituted cyclopentadienyl ring; each R n and R' m is a hydrocarbyl radical having 1-20 carbon atoms; R" is a structural bridge between the two Cp rings imparting stereorigidity to the Cp rings; Me is a transition metal; and each Q is a hydrocarbyl radical or is a halogen. R' m is selected so that (CpR' m ) is a sterically different substituted cyclopentadienyl ring than (CpR' n ). The use of a metallocene catalyst component with sterically different cyclopentadienyl rings in which one and only one of the distal positions of the cyclopentadienyl rings has a bulky group as a substituent produces isotactic polymer.

Process and catalyst for producing isotactic polyolefins

Metallocene catalysts and their preparation and use in the polymerization of olefins. Specifically, the catalysts and processes relate to polymerization of olefins in which an aluminum ionizing agent containing a triphenylcarbenium ion is utilized in preparing the catalyst. The preparation of an olefin polymerization catalyst comprising a metallocene-type catalyst and triphenylcarbenium tetrahedral aluminate is disclosed.

Cationic metallocene catalysts based on triphenylcarbenium aluminum

The invention is for a catalyst system for polymerization of olefins using an ionic mettallocene catalyst with aluminum alkyl. The metallocene catalyst is an ion pair formed from a neutral metallocene compound and an ionizing compound. The invention can be used in any method of producing ionic metallocene catalyst. Use of aluminum alkyl with an ionic metallocene catalyst eliminates the need for using methylaluminoxane (MAO). Catalysts produced by the method of this invention have high activity. The invention reduces catalyst poisons which cause low activity, no activity or uncontrolled polymerizations. Polymerizations using this catalyst system are reproducible and controllable.

Michael J. Elder

Papers

Preparation of metallocene catalysts for polymerization of olefins

Metallocene catalysts with Lewis acids and aluminum alkyls

Process and catalyst for producing isotactic polyolefins

Cationic metallocene catalysts based on triphenylcarbenium aluminum

Addition of aluminium alkyl for improved metallocene catalyst