Support materials for use with polymerization catalysts

Details Support materials for use with polymerization catalysts Support materials for use with polymerization catalysts

2000-12-07

2002-11-19

Lu, Caixia (Department: 1713)

Synthetic resins or natural rubbers -- part of the class 520 ser

Synthetic resins

Polymers from only ethylenic monomers or processes of...

C526S146000, C526S147000, C526S160000, C526S165000, C526S943000, C502S128000

Reexamination Certificate

active

06482904

ABSTRACT:

FIELD OF THE INVENTION
The present invention relates generally to the field of new support materials for use with polymerization catalysts. In particular, the present invention is directed to new catalyst systems comprising a polytetrafluoroethylene support material and a polymerization catalyst compound, to methods for preparing these supported catalyst systems, and their use in the polymerization of olefin(s).
BACKGROUND OF THE INVENTION
Developments in polymerization technology have provided more efficient, highly productive and economically enhanced catalyst systems and processes. Especially illustrative of these advances is the development of bulky ligand metallocene catalysts and of Group 15 atom containing metal catalysts. To utilize these catalyst compounds in industrial slurry or gas phases processes, it is useful that they be immobilized on a support or carrier.
The use of supported or heterogeneous catalysts in gas and slurry phase polymerization is important as a means of increasing process efficiencies by assuring that the forming polymeric particles achieve shape and density that improves reactor operability and ease of handling. Ineffective catalyst supports permit the production of polymeric fines and fouling of reactor walls or piping. This appears to be due to a number of possible reasons, including premature support particle fragmentation or catalyst desorption, both of which can lead to decrease in the control of polymerization. Polymer particle size and density can be degraded and efficiencies lost.
Typical heterogeneous catalyst systems include inorganic oxide supports, such as SiO
2
, Al
2
O
3
and MgO. These inorganic oxide supports, which may be used in concert with a catalyst activator compound, are available in a variety of particle sizes and porosities. However, silica and other inorganic oxide supports have several deficiencies. For example, the presence of water on the surface of inorganic oxide supports is known in the art to be a catalyst poison adversely affecting catalyst activity. To remove water from the surface, inorganic oxide supports must be calcined at high temperatures or chemically treated with appropriate reagents. In addition, inorganic oxides also readily adsorb other commonly occurring catalyst poisons, such as oxygen.
Moreover, with the emergence of discrete single-sited catalysts, research has shown that the use of such supports leads to a great deterioration of catalyst activity, often leading to prohibitively high catalyst costs in commercial applications. Further, certain catalysts bearing reactive functionalities (e.g., newer catalyst compounds and/or non-coordinating anions) are largely or entirely inactive when deposited on silica supports.
Where conventional Ziegler-Natta catalysts have been successfully prepared employing conventional silica (and other) support materials, experience continues to show that discrete metallocene and metallocene-type catalysts suffer significant activity losses when common supports are used. For catalysts that incorporate inexpensive precursors and display very high activities, such losses may be acceptable for commercial operation. However, for many catalysts, deterioration of catalytic activity through the use of conventional supporting materials can lead to prohibitively high catalyst costs, precluding their use from commercial applications. This is especially true for catalysts that possess metal to nitrogen and metal to oxygen bonds, or which employ non-coordinating anions for charge balance. It is likely that the activity losses observed upon supporting these catalysts arise from deleterious interactions of these sensitive species with Lewis basic and/or hydroxylic sites on the support.
Polytetrafluoroethylene (PTFE), sold under the trade name TEFLON, is a polymer similar in structure to polyethylene, consisting of a carbon chain with two fluorine atoms bonded to each carbon. TEFLON is typically used for lubricant free bushings and bearings, liners for equipment used in the storage and transportation of strong acids and organic solvents, as electrical insulation under high-temperature conditions, and in the familiar cooking surface that does not require the use of fats or oils.
There exists a need for improved catalyst systems utilizing new support materials, for methods of preparing catalyst systems utilizing new support materials and for polymerization process utilizing such supported catalyst systems. It is therefore an object of this invention to identify support materials that preserve both the activity and the polymer properties of “unsupportable” catalysts in the sense of traditional support materials, that will perform in existing or minimally-modified commercial catalyst feeding configurations. It is also an object of this invention to use several simple and commercially-available materials as supports for catalysts for use in polyolefin polymerization environments where the catalysts activity in solution, which is usually greater than when the catalyst is supported, is retained.
SUMMARY OF THE INVENTION
This invention provides a new catalyst system including polytetrafluoroethylene support materials, a catalyst compound and an activator compound, to methods of preparing the new catalyst system and to its use in the polymerization of olefin(s).
DETAILED DESCRIPTION OF THE INVENTION
Introduction
The catalyst compounds that may be utilized in the polytetrafluoroethylene supported catalyst systems of invention include bulky ligand metallocene catalyst compounds and Group 15 atom containing metal catalyst compounds.
Bulky Ligand Metallocene Catalyst Compounds
Polytetrafluoroethylene support materials may be utilized with the bulky ligand metallocene polymerization catalyst compounds described below. Generally, these catalyst compounds include half and full sandwich compounds having one or more bulky ligands bonded to at least one metal atom. Typical bulky ligand metallocene compounds are described as containing one or more bulky ligand(s) and one or more leaving group(s) bonded to at least one metal atom. In one preferred embodiment, at least one bulky ligands is &eegr;-bonded to the metal atom, most preferably &eegr;
5
-bonded to a transition metal atom.
The bulky ligands may be open, acyclic, or fused ring(s) or ring system(s) or a combination thereof. The ring(s) or ring system(s) of these bulky ligands are typically composed of atoms selected from Groups 13 to 16 atoms of the
Periodic Table of Elements. Preferably the atoms are selected from the group consisting of carbon, nitrogen, oxygen, silicon, sulfur, phosphorous, germanium, boron and aluminum or a combination thereof. Most preferably the ring(s) or ring system(s) are composed of carbon atoms such as but not limited to those cyclopentadienyl ligands or cyclopentadienyl-type ligand structures. The bulky ligands may also be a similar functioning ligand structure such as a pentadiene, a cyclooctatetraendiyl or an imide ligand. The metal atom is preferably selected from Groups 3 through 15 and the lanthanide or actinide series of the Periodic Table of Elements. Preferably the metal is a transition metal from Groups 4 through 12, more preferably Groups 4, 5 and 6, and most preferably the transition metal is from Group 4.
In one embodiment, the polytetrafluoroethylene support materials may be utilized with the bulky ligand metallocene catalyst compounds represented by the formula:
L
A
L
B
MQ
n
  (I)
where M is a metal atom from the Periodic Table of the Elements and may be a Group 3 to 12 metal or from the lanthanide or actinide series of the Periodic Table of Elements, preferably M is a Group 4, 5 or 6 transition metal, more preferably M is zirconium, hafnium or titanium. The bulky ligands, L
A
and L
B
, are open, acyclic, fused ring(s) or ring system(s) and are any ancillary ligand system, including unsubstituted or substituted, cyclopentadienyl ligands or cyclopentadienyl-type ligands, heteroatom substituted and/or heteroatom containing cyclopentadienyl-type ligands. Non-limiting examples of bulky ligands includ

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