Process for preparing carrier-borne transition metal catalysts

Details Process for preparing carrier-borne transition metal catalysts Process for preparing carrier-borne transition metal catalysts

1998-12-16

2001-07-24

Wu, David W. (Department: 1713)

Catalyst, solid sorbent, or support therefor: product or process

Catalyst or precursor therefor

Plural component system comprising a - group i to iv metal...

C502S117000, C502S152000, C526S160000, C526S943000, C526S348600

Reexamination Certificate

active

06265339

ABSTRACT:

The present invention relates to a process for preparing a supported transition metal catalyst comprising a particulate organic or inorganic support material, a transition metal complex and a compound capable of forming metallocenium ions.
The present invention also relates to a supported catalyst obtainable by this process, a process for preparing polymers by means of this catalyst and the use of these polymers for producing fibers, films and moldings.
Supported transition metal catalysts have been known for a long time and are, for example, used for olefin polymerization. The activity and productivity of these catalysts depends significantly on their process of preparation. The selection of the loading parameters generally attempts to achieve a sufficiently strong binding of the catalyst and possibly the cocatalysts to the support and also as homogeneous as possible a distribution of the active components on the support.
WO 94/28034 describes the preparation of a supported catalyst for olefin polymerization, where a metallocene complex together with an aluminoxane or methylaluminoxane in a liquid hydrocarbon is brought into contact with an inert support, typically silica gel, and the solvent is subsequently removed by distillation.
EP-A1-295 312 describes various processes for preparing supported olefin polymerization catalysts. A feature common to these processes is that a solution of an aluminoxane is brought into contact with a second solvent in which the aluminoxane is insoluble in the presence of a particulate organic or inorganic support, resulting in precipitation of the aluminoxane onto the support. In the various embodiments, first the aluminoxane and then a metallocene complex are precipitated stepwise onto the support or else a mixture of aluminoxane and metallocene complex is precipitated simultaneously.
However, the preparative methods described lead to supported catalysts which still leave something to be desired in terms of their activity and productivity.
It is an object of the present invention to find a process for preparing supported transition metal catalysts which leads to catalysts of higher productivity.
We have found that this object is achieved by a process for preparing a supported transition metal catalyst comprising a particulate organic or inorganic support material, a transition metal complex and a compound capable of forming metallocenium ions, which comprises the following process steps:
a) contacting a solution of a compound capable of forming metallocenium ions with a second solvent in which this compound is only sparingly soluble, in the presence of the support material,
b) removing at least part of the solvent from the support material and
c) contacting a solution of a mixture of a compound capable of forming metallocenium ions and a transition metal complex with a second solvent in which this mixture is only sparingly soluble, in the presence of the support material obtained as described in a) and b).
Furthermore, we have found a supported catalyst obtainable by this process, a process for preparing polymers by means of this catalyst and the use of these polymers for producing fibers, films and moldings.
Examples of suitable particulate organic or inorganic support material are polyolefins such as polyethylene, polypropylene, poly-1-butene and polymethyl-1-pentene and copolymers with the monomers on which these polymers are based, also polyesters, polyamides, polyvinyl chloride, polyacrylates and polymethacrylates and polystyrene. However, preference is given to inorganic support materials such as porous oxides, eg. SiO
2
, Al
2
O
3
, MgO, ZrO
2
, TiO
2
, B
2
O
3
, CaO, ZnO. Metal halides such as MgCl
2
are also suitable as supports. The support materials preferably have a particle diameter of from 1 to 300 &mgr;m, in particular from 30 to 70 &mgr;m. Examples of particularly preferred supports are silica gels, preferably those of the formula SiO
2
·a Al
2
O
3
, where a is a number in the range from 0 to 2, preferably from 0 to 0.5; these are thus aluminosilicates or silicon dioxide. Such products are commercially available, eg. Silica Gel 332 from Grace.
Particularly suitable silica gels are those which have voids and channels whose macroscopic proportion by volume in the total particle is in the range from 5 to 30%. Preference is given to those silica gel supports which have a mean particle diameter of from 5 to 200 &mgr;m and a mean particle diameter of the primary particles of from 1 to 20 &mgr;m, in particular from 1 to 10 &mgr;m. The primary articles [sic] here are porous, granular particles. The primary particles have pores having a diameter of, in particular, from 1 to 1000 Ångström. Furthermore, the inorganic oxides to be used additionally have voids and channels having a diameter of from 1 to 20 &mgr;m. These silica gels also have, in particular, a pore volume of from 0.1 to 10 cm
3
/g, preferably from 1.0 to 5.0 cm
3
/g, and a specific surface area of from 10 to 1000 m
2
/g. Such products are commercially available, e.g. Sylopol 2101 (from Grace), ES 70X (from Crosfield) or MS 3040 (from PQ Corporation). Further characteristics of such silica gels are described in the previous German Patent Application 19 623 225.2, whose contents are incorporated by reference into the present document.
Examples of suitable transition metal complexes are metal complexes containing metallocene ligands or other organic ligands such as &bgr;-diketiminate or azaallyl ligands, as are described, for example, in J. Organomet. Chem. 500 (1995), 203-217, in WO 95/33776 and also in the previous German Patent Application 19 616 523.7. Particularly suitable transition metal complexes for use in the process of the present invention are metallocene complexes of elements of the 4th and 5th transition groups of the Periodic Table. Particularly suitable transition metal complexes are, furthermore, those containing benzindenyl ligands. These benzindenyl ligands can be substituted or unsubstituted.
Suitable metallocene complexes are in particular those of the general formula III
where the substituents have the following meanings:
M is titanium, zirconium, hafnium, vanadium, niobium or tantalum,
X is fluorine, chlorine, bromine, iodine, hydrogen, C
1
-C
10
-alkyl, C
6
-C
15
-aryl, alkylaryl having from 1 to 10 carbon atoms in the alkyl radical and from 6 to 20 carbon atoms in the aryl radical, —OR
7
or —NR
7
R
8
,
where
R
7
and R
8
are C
1
-C
10
-alkyl, C
6
-C
15
-aryl, alkylaryl, arylalkyl, fluoroalkyl or fluoroaryl each having from 1 to 10 carbon atoms in the alkyl radical and from 6 to 20 carbon atoms in the aryl radical,
R
2
to R
6
are hydrogen, C
1
-C
10
-alkyl, 5- to 7-membered cycloalkyl which may in turn bear a C
1
-C
10
-alkyl group as substituent, C
6
-C
15
-aryl or arylalkyl, where two adjacent radicals may also together form a saturated or unsaturated cyclic group having from 4 to 15 carbon atoms, or Si(R
9
)
3
where
R
9
is C
1
-C
10
-alkyl, C
3
-C
10
-cycloalkyl or C
6
-C
15
-aryl,
where the radicals
R
10
to R
14
are hydrogen, C
1
-C
10
-alkyl, 5- to 7-membered cycloalkyl which may in turn bear a C
1
-C
10
-alkyl group as substituent, C
6
-C
15
-aryl or arylalkyl and where two adjacent radicals may also together form a saturated or unsaturated cyclic group having from 4 to 15 carbon atoms, or Si(R
15
)
3
where
R
15
is C
1
-C
10
-alkyl, C
6
-C
15
-aryl or C
3
-C
10
-cycloalkyl,
or where the radicals R
5
and Z together form a group —R
16
—A—, where
═BR
17
, ═AlR
17
, —Ge—, —Sn—, —O—, —S—, ═SO, ═SO
2
, ═NR
17
, ═CO, ═PR
17
or ═P(O)R
17
,
where
R
17
, R
18
and R
19
are identical or different and are hydrogen, halogen, C
1
-C
10
-alkyl, C
1
-C
10
-fluoroalkyl, C
6
-C
10
-fluoroaryl, C
6
-C
10
-aryl, C
1
-C
10
-alkoxy, C
2
-C
10
-alkenyl, C
7
-C
40
-arylalkyl, C
8
-C
40
-arylalkenyl or C
7
-C
40
-alkylaryl or two adjacent radicals together with the atoms connecting them form a ring, and
M
2
is silicon, germanium or tin,
R
20
is C
1
-C
10
-alkyl, C
6
-C
15
-aryl, C
3
-C
10
-cycloa

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