Catalyst – solid sorbent – or support therefor: product or process – Catalyst or precursor therefor – Organic compound containing
Reexamination Certificate
1999-11-01
2002-06-04
Bell, Mark L. (Department: 1755)
Catalyst, solid sorbent, or support therefor: product or process
Catalyst or precursor therefor
Organic compound containing
C502S081000, C502S118000, C502S119000, C502S120000, C502S132000, C502S133000
Reexamination Certificate
active
06399535
ABSTRACT:
FIELD OF THE INVENTION
The invention relates to coordination catalyst systems, which comprise a support-activator in agglomerate form and a coordination catalyst component and methods of their preparation.
BACKGROUND OF THE INVENTION
Coordination catalyst systems, which are usually based on transition metal compounds of Groups 3 to 10 and organometallic compounds of Group 13 of the Periodic Table of the Elements, are exceptionally diverse catalysts which are employed in chemical reactions of and with olefinically unsaturated compounds. Such reactions are embodied in processes for the preparation of olefin polymers by coordination polymerization.
The preparation of polyethylene of increased density (high-density polyethylene, HDPE) and of polymers and copolymers of ethylene, propylene or other 1-alkenes is of considerable industrial importance.
The prevailing belief on the reaction mechanism of coordination catalysts is that a transition metal compound forms a catalytically active center to which the olefinically unsaturated compound bonds by coordination in a first step. Olefin polymerization takes place via coordination of the monomers and a subsequent insertion reaction into a transition metal-carbon or a transition metal-hydrogen bond.
The presence of organometallic compounds (e.g., organoaluminum compounds such as methylalumoxane) in the coordination catalyst systems or during the catalyzed reaction is thought to be necessary in order to activate the catalyst, or maintain its activity, by reduction and, where appropriate, alkylation or formation of a complex system. These compounds were therefore also called cocatalysts. The compound containing the transition metal atom, which is eventually activated, is typically called the pre-catalyst and after activation, the primary catalyst.
The best known industrially used catalyst systems for coordination polymerization are those of the “Ziegler-Natta catalyst” type and the “Phillips catalyst” type. The former comprise the reaction product of a metal alkyl or hydride of elements of the first three main groups of the Periodic Table and a reducible compound of a transition metal element of Groups 4 to 7 the combination used most frequently comprising an aluminum alkyl, such as diethylaluminum chloride, and titanium (IV) chloride. More recent highly active Ziegler-Natta catalysts are systems in which the titanium compound is fixed chemically to the surface of magnesium compounds, such as, in particular, magnesium chloride.
More recent developments have focused on single-site catalyst systems. Such systems are characterized by the fact that their metal centers behave alike during polymerization thus making very uniform polymers.
Catalysts are judged to behave in a single-site manner when the polymer they make meets some basic criteria (e.g., narrow molecular weight distribution, or uniform comonomer distribution). Thus, the metal can have any ligand set around it and be classified as “single-site” as long as the polymer that it produces has certain properties.
Includable within single-site catalyst systems are metallocene catalysts and constrained geometry catalysts.
A “metallocene” is conventionally understood to mean a metal (e.g., Zr, Ti, Hf, Sc, Y, Vi or La) complex that is bound to two cyclopentadienyl (Cp) rings, or derivatives thereof, such as indenyl, tetrahydroindenyl, fluorenyl and mixtures. In addition to the two Cp ligands, other groups can be attached to the metal center, most commonly halides and alkyls. The Cp rings can be linked together (so-called “bridged metallocene” structure), as in most polypropylene catalysts, or they can be independent and freely rotating, as in most (but not all) metallocene-based polyethylene catalysts. The defining feature is the presence of two Cp ligands or derivatives.
Metallocene catalysts can be employed either as so-called “neutral metallocenes” in which case an alumoxane, such as methylalumoxane, is used as a co-catalyst, or they can be employed as so-called “cationic metallocenes” which incorporate a stable and loosely bound non-coordinating anion as a counter ion to a cationic metal metallocene center. Cationic metallocenes are disclosed in U.S. Pat. Nos. 5,064,802; 5,225,500; 5,243,002; 5,321,106; 5,427,991; and 5,643,847; and EP 426 637 and EP 426 638.
“Constrained geometry” is a term that refers to a particular class of organometallic complexes in which the metal center is bound by only one modified Cp ring or derivative. The Cp ring is modified by bridging to a heteroatom such as nitrogen, phosphorus, oxygen, or sulfur, and this heteroatom also binds to the metal site. The bridged structure forms a fairly rigid system, thus the term “constrained geometry”. By virtue of its open structure, the constrained geometry catalyst can produce resins (long chain branching) that are not possible with normal metallocene catalysts.
Still more recently, late transitional metal (e.g., Fe, Co, Ni, or Pd) bidentate and tridentate catalyst systems have been developed. Representative disclosures of such late transition metal catalysts are found in U.S. Pat. No. 5,880,241 and its divisional counterparts U.S. Pat. Nos. 5,880,323; 5,866,663; 5,886,224; and 5,891,963, and PCT International Application Nos. PCT/US98/00316; PCT/US97/23556; PCT/GB99/00714; PCT/GB99/00715; and PCT/GB99/00716.
Both the single site and late transition metal pre-catalysts typically require activation to form a cationic metal center by an organometal Lewis acid (e.g., methyl alumoxane (MAO)) (characterized as operating through a hydrocarbyl abstraction mechanism). Such activators or cocatalysts are pyrophoric (or require pyrophoric reagents to make the same), and are typically employed in quantities which are multiples of the catalyst. Attempts to avoid such disadvantages have led to the development of borane (e.g., trispentaflurophenylborane) and borate (e.g., ammonium tetrakispentaflurophenylborate) activators which are non-pyrophoric but more expensive to manufacture. These factors complicate the development of heterogeneous versions of such catalyst systems in terms of meeting cost and performance targets.
Use of these catalysts and related types in various polymerization processes can give products with sometimes extremely different properties. In the case of olefin polymers, which are generally known to be important as materials, the suitability for particular applications depends, on the one hand, on the nature of the monomers on which they are based and on the choice and ratio of comonomers and the typical physical parameters which characterize the polymer, such as average molecular weight, molecular weight distribution, degree of branching, degree of crosslinking, crystallinity, density, presence of functional groups in the polymer and the like, and on the other hand, on properties resulting from the process, such as content of low molecular weight impurities and presence of catalyst residues, and last but not least on costs.
In addition to realization of the desired product properties, other factors are decisive for evaluating the efficiency of a coordination catalyst system, such as the activity of the catalyst system, that is to say the amount of catalyst required for economic conversion of a given amount of olefin, the product conversion per unit time and the product yield. Catalyst systems such as the Fe or Co catalysts described herein, which exhibit high productivity and high specificity in favor of a low degree of branching of the polymer, are sought for certain applications. Catalyst systems utilizing the Ni and Pd catalysts described herein seek to achieve highly branched polymers with reasonable productivity.
The stability and ease of handling of the catalyst or its components is another factor which affects the choice of commercial embodiments thereof. Practically all known coordination catalysts are extremely sensitive to air and moisture to varying degrees. Coordination catalysts are typically reduced in their activity or irreversibly destroyed by access to (atmospheric) oxygen and/or water. Most Ziegle
Carney Michael John
Denton Dean Alexander
Shih Keng-Yu
Bell Mark L.
Maggio Robert A.
Pasterczyk J.
W. R. Grace & Co.,-Conn.
LandOfFree
Coordination catalyst systems employing agglomerated metal... does not yet have a rating. At this time, there are no reviews or comments for this patent.
If you have personal experience with Coordination catalyst systems employing agglomerated metal..., we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Coordination catalyst systems employing agglomerated metal... will most certainly appreciate the feedback.
Profile ID: LFUS-PAI-O-2977030