Catalyst – solid sorbent – or support therefor: product or process – Catalyst or precursor therefor – Plural component system comprising a - group i to iv metal...
Reexamination Certificate
1999-12-09
2002-01-08
Bell, Mark L. (Department: 1755)
Catalyst, solid sorbent, or support therefor: product or process
Catalyst or precursor therefor
Plural component system comprising a - group i to iv metal...
C585S721000, C585S722000, C585S726000, C585S727000, C585S730000, C585S732000, C502S123000, C502S167000, C502S168000, C502S169000, C502S170000
Reexamination Certificate
active
06337297
ABSTRACT:
BACKGROUND OF THE INVENTION
(1) Field of the Invention
This invention relates to a catalyst for trimerization of ethylene and a process for trimerizing ethylene using the catalyst. More specifically, it relates to a catalyst exhibiting an enhanced activity for trimerization of ethylene to produce 1-hexene, which is used as a comonomer for the production of linear low-density polyethylene (LLDPE), and further to a process for trimerizing ethylene by which 1-hexene can be produced effectively and highly selectively.
(2) Related Art
It is known to use a chromium compound as a catalyst for trimerization of ethylene to give 1-hexene. For example, a catalyst system comprising a chromium compound, polyhydrocarbylaluminum oxide and a donor ligand is described in Japanese Unexamined Patent Publication No. (hereinafter abbreviated to “JP-A”) S62-265237. A catalyst system comprising a chromium compound, a pyrrole-containing compound, an alkyl metal compound and a halide is described in JP-A H6-239920. A catalyst system comprising a chromium compound, an alkyl metal compound, and an acid amide or imide compound is described in JP-A HB-59732. A catalyst comprising (i) a complex of chromium salt with a multidentate ligand selected from phosphine, arsine and stibine, and (ii) aluminoxane is described in JP-A H6-298673. A catalyst comprising (i) a chromium-chlorine complex or alkyl chromium complex having a specific nitrogen ligand and (ii) an aluminum compound is described in JP-A H10-7712. A catalyst comprising (i) a chromium complex having a cyclic polyamine or hydro-tris(pyrazolyl)borate ligand and (ii) an alkyl aluminum compound is described in JP-A HIO-231317.
However, these chromium catalysts have problems as explained below.
When the catalyst of JP-A S62-265237 is used for trimerization of ethylene, a salient amount of polyethylene is produced in addition to 1-hexene. Further, polyhydrocarbyl-aluminum oxide (i.e., aluminoxane), which is one ingredient of the catalyst, is a polymer prepared by reacting an alkyl aluminum with water, and therefore, it is difficult to prepare aluminoxane having a predetermined quality, and this leads to reduction of reproducibility of trimerization reaction of ethylene.
When the catalyst of JP-A H6-239920 is used, the amount of polyethylene produced can be reduced. However, a pyrrole-containing compound, which is one ingredient of the catalyst, is extremely unstable to air, and readily deteriorated and colored. Thus, a pyrrole-containing compound is troublesome to handle, and a treating process or apparatus for removing a coloring matter from the catalyst or purifying the catalyst is needed.
As for the catalyst of JP-A H8-59732, among the acid amide or imide compounds, which are one ingredient of the catalyst, maleimide is optimum for the catalytic activity for trimerization of ethylene. However, maleimide has problems such that it has a poor solubility in an organic solvent and the catalyst is troublesome to prepare, and further that it is not readily commercially available and is expensive.
The catalyst of JP-A H6-298673 has a problem such that alminoxane used as one ingredient of the catalyst is difficult to synthesize with a good reproducibility. The catalyst of JP-A H10-7712 has a poor activity for trimerization of ethylene. The catalyst of JP-A H10-231317 has problems such that polyethylene is undesirably produced in an amount larger than that of 1-hexene, and that the selectivity to 1-hexene among oligomers is low.
SUMMARY OF THE INVENTION
In view of the foregoing, a primary object of the present invention is to provide a catalyst having good handling characteristics and exhibiting an enhanced activity for trimerization of ethylene to produce 1-hexene, which is used as a comonomer for the production of linear low-density polyethylene (LLDPE).
Another object of the present invention is to provide a process for trimerizing ethylene by which 1-hexene can be produced effectively and highly selectively.
In one aspect of the present invention, there is provided a catalyst for trimerization of ethylene which comprises:
(a) a chromium complex having a neutral multidentate ligand having a tripod structure, represented by the following formula (1):
ACrJ
n
Q
3-n
(1)
wherein A is a neutral multidentate ligand having a tripod structure, J is a carbonyl ligand or a halogen atom, n is an integer of 0 to 3, and Q is at least one member selected from the group consisting of a hydrogen atom, a hydrocarbon group having 1 to 10 carbon atoms, a carboxylate group having 1 to 10 carbon atoms, a diketonato group having 3 to 10 carbon atoms, an amide group, an imide group, an alkoxide group having 1 to 10 carbon atoms, a thioalkoxide group having 1 to 10 carbon atoms, an arene ligand having 6 to 15 carbon atoms, an alkene ligand having 2 to 10 carbon atoms, an alkyne ligand having 2 to 15 carbon atoms, an amine ligand, an imine ligand, a nitrile ligand, an isonitrile ligand, a phosphine ligand, a phosphine oxide ligand, a phosphite ligand, an ether ligand, a sulfide ligand, a sulfone ligand and a sulfoxide ligand, and
(b) a metal alkyl compound.
Preferably the catalyst further comprises (c) at least one compound selected from aromatic tertiary amine compounds, except for an imine, and nitrogen-containing heterocyclic compounds, and/or (d) a radical anion compound.
In another aspect of the present invention, there is provided a process for trimerizing ethylene, characterized in that ethylene is trimerized in the presence of the above-mentioned catalyst.
DESCRIPTION OF THE PREFERRED EMBODIMENTS
Catalyst for Trimerization of Ethylene
The catalyst of the invention comprises a chromium complex having a neutral multidentate ligand having a tripod structure, represented by the above formula (1) as one indispensable ingredient. The neutral multidentate ligand having a tripod structure coordinated in the chromium complex is not particularly limited, and includes, for example, those which are represented by the following formulae (2) and (3).
wherein j, k and m independently represent an integer of 0 to 6, each D
1
independently represents a divalent hydrocarbon group which may have a substituent, each L
1
independently represents a substituent containing an element of group 14, 15, 16 or 17 of the periodic table, G
1
represents a carbon or silicon atom, and R
1
represents a hydrogen atom, an alkyl group having 1 to 10 carbon atoms or an aryl group having 6 to 10 carbon atoms.
wherein a, b and c independently represent an integer of 0 to 6, u represents an integer of 0 or 1, each D
2
independently represents a divalent hydrocarbon group which may have a substituent, each L
2
independently represents a substituent containing an element of group 14, 15, 16 or 17 of the periodic table, G
2
represents a nitrogen or phosphorus atom, and R
2
represents an oxygen or sulfur atom.
The divalent hydrocarbon groups D
1
in formula (2) and D
2
in formula (3) are not particularly limited, and include, for example, alkylene, cycloalkylene, phenylene, tolylene and xylylene groups. D
1
and D
2
may have a substituent, for example, an alkyl group such as methyl or ethyl, and an alkoxy group such as methoxy and ethoxy.
The substituents L
1
in formula (2) and L
2
in formula (3), which contain an element of group 14, 15, 16 or 17 of the periodic table, are not particularly limited. As specific examples of the substituents L
1
and L
2
, there can be mentioned alkoxy groups such as methoxy, ethoxy, propoxy and butoxy; aryloxy groups such as phenoxy and 2,6-dimethylphenoxy; alkylthio groups such as methylthio, ethylthio, propylthio and butylthio; arylthio groups such as phenylthio and tolylthio; dialkylamino groups such as dimethylamino, diethylamino and bis(trimethylsilyl)amino; diarylamino groups such as diphenylamino; alkylarylamino groups such as methylphenylamino; dialkylphosphino groups such as dimethylphosphino and diethylphosphino; diarylphosphino groups such as diphenylphosphino and ditolylphosphino; and alkylarylphosphino groups such as methylphenylphosphino.
The
Mimura Hideyuki
Murakita Hideyuki
Oguri Motohiro
Okada Hisanori
Yamamoto Toshihide
Bell Mark L.
Pasteczyk J.
Tosoh Corporation
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