Catalyst – solid sorbent – or support therefor: product or process – Catalyst or precursor therefor – Organic compound containing
Reexamination Certificate
2002-10-02
2004-03-09
Choi, Ling-Siu (Department: 1713)
Catalyst, solid sorbent, or support therefor: product or process
Catalyst or precursor therefor
Organic compound containing
C502S103000, C502S116000, C502S132000, C526S160000, C526S943000, C526S131000, C526S130000, C526S135000
Reexamination Certificate
active
06703340
ABSTRACT:
FIELD OF THE INVENTION
This invention relates to a method for production of catalyst compositions useful for addition reactions of olefinically unsaturated monomers, e.g., polymerization. The invention is particularly useful in coordination polymerization processes that utilize supported compounds for slurry or gas phase polymerization of olefinically unsaturated monomers, and those processes themselves. The ionic catalyst compositions comprise the final product of the interaction between an aluminum alkyl, a metallocene, an anionic activator, and a support.
BACKGROUND OF THE INVENTION
Coordination catalyzed polymerization of olefinically unsaturated monomers is well known and has led to the proliferation in modem society of elastomeric and plastic compositions of matter, such as polyethylene, polypropylene, and ethylene propylene rubber. Early pioneers utilized transition metal compounds the ligands of which were non-organic moieties, such as halides, with activators such as aluminum alkyls. Later development extended this work to bulky organo ligand-containing (e.g., eta
5
-cyclopentadienyl) transition metals (“metallocenes”) with activators such as alumoxanes (a partial hydrolysis product of an aluminum alkyl). More recent developments have shown the-effectiveness of ionic catalysts comprised of metallocene cations activated by non-coordinating anions, see for example EP-A-277,004 and U.S. Pat. No. 5,198,401. These references described protonation of metallocene compounds by anion precursors to form stable “ionic” catalysts.
Such ionic catalysts have shown to varying degrees significant sensitivity to catalyst poisons present in monomer feed streams, or in recycled fluid streams, in the polymerization process and have posed problems for use with inert oxide supports that typically have either or both of retained moisture or polar hydroxyl groups. Accordingly, processes have been developed to utilize poison scavenging compounds, as for example alkyl aluminums or alumoxanes, for solution polymerization and to remove or neutralize polar groups retained in or on inert oxide supports. For example, see U.S. Pat. No. 5,153,157, describing Group-IIIA metal scavenger compounds, and WO-A-91/09882, WO-A-94/00500 and WO-A-94/03506 describing supporting techniques utilizing similar compounds. U.S. Pat. No. 5,206,197 describes enhanced polymerization of styrene where the ionic catalyst systems include a metal hydrocarbyl, and, which may be supported. All such documents are referred to herein for their description of metallocene compounds, ionic activators, and useful scavenging compounds.
Whereas these ionic catalyst in unsupported form exhibit acceptable levels of productivity, as measured by a part per million (ppm) content of the transitional metal retained as a residue in the polymer product of about 1 to 1.5 ppm, when placed on a support such as silica, for use in a gas phase polymerization procedure, the productivity of these ionic catalyst often drops to an unacceptable, level i.e., the ppm content of transition metal retained as a residue in the polymer product becomes greater than about 1 to 1.5 ppm.
It is desirable to develop a process for producing a supported form of ionic transition metal catalyst that allows it to maintain its high productivity under gas phase polymerization conditions.
SUMMARY OF THE INVENTION
This invention comprises a process for the production of an ionic transition metal catalyst in supported form than is highly productive under gas phase polymerization conditions. In the process of the invention an aluminum alkyl is added to a suitable solvent after which a neutral metallocene compound is added to the aluminum alkyl solution under stirring in a quantity that provides for a ratio of Al to transition metal of 2:1 to 200:1, preferably at least 25:1, and more preferably at least 50:1 and stirring is continued until substantially all material is dissolved. To this metallocene-aluminum alkyl solution is next added an ionic compound the anionic portion of which is a non-coordinating anion (NCA) as hereafter defined, under stirring until all materials are substantially dissolved. The ionic compound is preferably added in a quantity that provides for a ratio of NCA to transition metal of at least 1:1. Next the support particles are added to the solution and thereafter the solution is heated to at least 40° C., and preferably 90° C., and held at this elevated temperature for at least 0.50 hour, and preferably for at least one hour. Thereafter the solvent is removed and the supported catalyst is dried, preferably under vacuum. A supported ionic catalyst produced in this manner is at least about 150% to 350% more productive under gas phase polymerization conditions than an otherwise identical supported metallocene catalyst that is co-catalyzed with methyl alumoxane.
DETAILED DESCRIPTION OF THE INVENTION
The supported catalyst formed by the process of this invention comprises the product of a sequence of reaction steps wherein first there occurs in a suitable solvent a reaction between a metallocene and an aluminum alkyl to produce a first reaction product that in turn is reacted with an ionic compound that provides a non-coordinating anion (NCA) to the transition metal of the first reaction product after which the resulting transition metal-NCA reaction product is exposed to a support material that is added to the solvent mixture which then elevated in temperature for a period of time before removal of the solvent to recover the catalyst as a free flowing powder.
The Transition Metal Component of the Catalyst
Any catalytically active transition metal compound is suitable in accordance with the invention, including the known transition metal compounds useful in traditional Ziegler-Natta coordination polymerization and, as well, the metallocene compounds similarly known to be useful in coordination polymerization, when such compounds are capable of catalytic activation by an anionic activator. These will typically include transition metal compounds where the metal is in a d
0
oxidation state, that is where the metal has its highest oxidation number, and wherein at least one metal ligand can be protonated by the anionic activator, particularly those ligands including hydride, alkyl and silyl. Ligands capable of protonation and transition metal compounds comprising them include those described in the background art, see for example EP-A-277,003, EP-A-277,004 and U.S. Pat. No. 5,198,401. Synthesis of these compounds is well known from the published literature.
Additional metallocene compounds appear in the patent literature, for example EP-A-0 129 368, U.S. Pat. Nos. 4,871,705, 4,937,299, 5,324,800 EP-A-0-418 044, EP-A-0 591 756, WO-A-92/00333 and WO-A-94/01471. Such metallocene compounds can be described for this invention as mono-, bis, or tris-cyclopentadienyl substituted Group 4, 5, 6, 9, or 10 transition metal compounds wherein the cyclopentadienyl substituents themselves may be substituted with one or more groups and may be bridged to each other, or may be bridged through a heteroatom to the transition metal. The size and constituency of the cyclopentadienyl substituents and bridging elements are not critical to the preparation of the ionic catalyst systems of the invention but should normally be selected in the literature described manner to enhance the polymerization activity and polymer characteristics being sought. Preferably the cyclopentadienyl (or substituted cyclopentadienyl, such as indenyl or substituted indenyl) rings, when bridged to each other, will be lower alkyl-substituted (C
1
to C
6
) in the 2 position additionally and comprise alkyl, cycloalkyl, aryl, alkylaryl and or arylalkyl substituents, the latter as either of fused or pendant ring structures including multi-ring structures, for example, those of U.S. Pat. Nos. 5,278,264 and 5,304,614. Such substituents should each have essentially hydrocarbyl characteristics and will typically contain up to 30 carbon atoms but may be hetero-atom containing with not more than 1-3 non-hydrogen/carbon at
Awe Michael D.
Muruganandam Natarajan Anand
Yang Xinmin
Choi Ling-Siu
Univation Technologies LLC
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