JP2002172327A - Trimerization catalyst of ethylene and method for trimerizing ethylene using the same - Google Patents

Abstract

PROBLEM TO BE SOLVED: To manufacture 1-hexene efficiently and highly selectively from ethylene. SOLUTION: A trimerization catalyst of ethylene is obtained by bringing a chromium complex having a neutral multidentate ligand, which has a tripod type structure represented by ACrBn (n is an integer of 1-3, A is a neutral multidentate ligand having a tripod type structure, Cr is a chromium atom and B is at least one component selected from the group consisting of a hydrogen atom, a halogen atom and a straight chain or branched alkyl group), into contact with an alkyl metal compound in a solution containing 10 vol.% or more of an alkane compound. This catalyst is used in the trimerization of ethylene.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

TECHNICAL FIELD The present invention relates to a catalyst for trimerizing ethylene and a method for trimerizing ethylene using the catalyst. More specifically, linear low-density polyethylene (LLD)
The present invention relates to an ethylene trimerization catalyst for efficiently and highly selectively producing 1-hexene useful as a raw material comonomer for PE) from ethylene, and a method for ethylene trimerization using the catalyst.

[0002]

2. Description of the Related Art It is known to use a chromium compound as a catalyst in a process for obtaining 1-hexene by trimerizing ethylene. For example, JP-A-62-265237 discloses a catalyst system comprising a chromium compound, polyhydrocarbyl aluminum oxide and a donor ligand. JP-A-6-239920 discloses a catalyst system comprising a chromium compound, a pyrrole-containing compound, a metal alkyl compound and a halide, and JP-A-8-59732 discloses a chromium compound, a metal alkyl compound and an acid amide or imide. A catalyst system comprising a compound is disclosed.

JP-A-6-298673 discloses a catalyst comprising an aluminoxane and a coordination complex of chromium salt with phosphine, arsine and / or stibine which is a polydentate ligand. Further, Japanese Patent Application Laid-Open
Japanese Patent Application Laid-Open No. Hei 10-231317 discloses a catalyst comprising an aluminum compound and a chlorine complex or an alkyl complex of chromium coordinated with a specific nitrogen ligand.
A catalyst comprising a chromium complex coordinated with a cyclic polyamine or hydrotris (pyrazolyl) borate and an alkylaluminum compound is disclosed.

[0004]

However, Japanese Patent Application Laid-Open No. Sho 62-62
The method described in Japanese Patent Publication No. 265237 has a disadvantage that a large amount of polyethylene is by-produced simultaneously with 1-hexene. The method described in Japanese Patent Application Laid-Open No. 6-239920 has a considerable improvement in this point, with little by-product of polyethylene. However, the pyrrole-containing compound as a component of the catalyst is a substance which is extremely unstable to air. Therefore, it is easily colored and deteriorated. Therefore, not only is it difficult to handle, but it is not sufficient as an industrial catalyst because it requires a treatment for removing coloring components or a new device after completion of the reaction. In the method described in JP-A-8-59732, it is necessary to use a specific imide compound (maleimide) in order to obtain an activity in a compound group of an acid amide or an imide compound which is a component of the catalyst. Since maleimide has low solubility, preparation of the catalyst is complicated, it is difficult to obtain and expensive, and there is a problem in terms of economic efficiency. In the method described in JP-A-6-298673,
There is a problem in the reproducibility of the embodiment. The method described in JP-A-10-7712 has a problem that the catalytic activity is low. The method described in JP-A-10-231317 discloses
There is a drawback that the production of polyethylene is large and the selectivity of 1-hexene in the oligomer is low.

The present invention has been made in view of the above-mentioned problems, and an object of the present invention is to produce 1-hexene useful as a raw material comonomer of LLDPE from ethylene efficiently and highly selectively, and to facilitate its handling. An object of the present invention is to provide a catalyst for trimerizing ethylene and a method for trimerizing ethylene using the catalyst.

[0006]

Means for Solving the Problems The inventors of the present invention have conducted intensive studies to solve the above-mentioned problems, and as a result, it has been found that a specific polydentate configuration is obtained in a state where 10% by volume or more of an alkane compound is present in a solvent. The trimerization catalyst obtained by contacting the ligand-coordinated chromium complex with the alkyl metal compound is stable and easy to handle, and when it is used, the ethylene trimerization reaction proceeds with high activity, resulting in high selectivity. It has been found that 1-hexene is produced, and the present invention has been completed.

That is, the present invention provides a catalyst for trimerizing ethylene obtained by contacting a chromium complex coordinated with a neutral polydentate ligand having a tripodal structure with an alkyl metal compound in the presence of an alkane solvent; It relates to a method for trimerizing ethylene using the same.

[0008]

Next, the present invention will be described in more detail.

In the present invention, as one component constituting the ethylene trimerization catalyst, the following general formula (1) ACrB _n (1) (where n is an integer of 1 to 3; A is a tripod-type structure) Wherein Cr represents a chromium atom, B represents one or more selected from the group consisting of a hydrogen atom, a halogen atom, and a linear or branched alkyl group.) A chromium complex coordinated with a neutral polydentate ligand having a tripod-type structure is used.

The neutral polydentate ligand having a tripod-type structure to be coordinated with the chromium complex is not particularly limited. For example, the following general formula (2)

[0011]

Embedded image

(Where j, k, and m are each independently 0
6 to an integer. D ¹ is each independently a divalent hydrocarbon group which may have a substituent, and L ¹ is each independently a substituent containing an element of Group 14, 15, 15, 16 or 17 of the periodic table. Represent. G ¹ represents carbon or silicon; 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. ) Or the following general formula (3)

[0013]

Embedded image

(Where a, b, and c each independently represent 0
And u is an integer of 0 or 1. D ²
Are each independently a divalent hydrocarbon group which may have a substituent, and L ² is each independently a group 14 or 15 of the periodic table.
Represents a substituent containing a Group 6, 16 or 17 element.
G ² represents a nitrogen atom or a phosphorus atom, and R ² represents an oxygen atom or a sulfur atom. ) Are preferred.

In the above general formulas (2) and (3), D
There are no particular restrictions on the ¹ and D ^2, for example, an alkylene group, a cycloalkylene group, a phenylene group, a tolylene group and a xylylene group. Also,
Examples of the substituent include alkyl groups such as a methyl group and an ethyl group, and alkoxy groups such as a methoxy group and an ethoxy group.

In the general formulas (2) and (3), the substituents containing elements belonging to groups 14, 15, 16 or 17 of the periodic table represented by L ¹ and L ² are not particularly limited. For example, methoxy group, ethoxy group, propoxy group, alkoxy groups such as butoxy group, phenoxy group,
Aryloxy groups such as 2,6-dimethylphenoxy group, alkylthio groups such as methylthio group, ethylthio group, propylthio group and butylthio group, arylthio groups such as phenylthio group and tolylthio group, dimethylamino group,
Dialkylamino groups such as diethylamino group and bis (trimethylsilyl) amino group; diarylamino groups such as diphenylamino group; alkylarylamino groups such as methylphenyl group; dialkylphosphone groups such as dimethylphosphino group and diethylphosphino group. Examples include diarylphosphino groups such as fino groups, diphenylphosphino groups and ditolylphosphino groups, and alkylarylphosphino groups such as methylphenylphosphino groups.

Further, a furyl group, benzofuryl group, thienyl group, benzothienyl group, pyrazolyl group, triazolyl group, tetrazolyl group, pyridyl group, imidazolyl group, benzimidazolyl group, indazolyl group, quinolyl group, isoquinolyl group, oxazolyl group, thiazole group And the like. Heterocyclic groups containing Group 14, 14, 15, 16 or 17 elements of the periodic table. Examples of on-ring substituents of these heterocyclic groups include a methyl group, an ethyl group, a propyl group, a butyl group, an octyl group, a phenyl group and the like.

Although R ¹ in the general formula (2) is not particularly limited, examples thereof include a hydrogen atom, a methyl group, an ethyl group, a propyl group, a butyl group, a benzyl group, a hydroxymethyl group, a cyanoethyl group and an allyl group. And a C1-C10 alkyl group, such as a trifluoropropyl group, and a C6-C10 aryl group, such as a phenyl group, a p-methylphenyl group, and a p-chlorophenyl group.

The neutral tridentate ligand having a tripod-type structure represented by the above general formulas (2) and (3) is not particularly limited. Examples of the polydentate ligand having a substituent containing a Group 11 or Group 17 element include tris (methoxymethyl) methane, 1,1,1
-Tris (methoxymethyl) ethane, 1,1,1-tris (methoxymethyl) propane, 1,1,1-tris (methoxymethyl) butane, 1,1,1-tris (ethoxymethyl) ethane, 1,1 1,1-Tris (propoxymethyl) ethane, 1,1,1-tris (butoxymethyl) ethane, 1,1,1-tris (phenoxymethyl)
Oxygen-containing tridentate ligands such as ethane, 1,1,1-tris (methylthiomethyl) ethane, 1,1,1-tris (butylthiomethyl) ethane, 1,1,1-tris (phenylthiomethyl) ) Sulfur-containing tridentate ligands such as ethane,
1,1-tris (dimethylaminomethyl) ethane, 1,
Nitrogen-containing tridentate ligands such as 1,1-tris (diphenylaminomethyl) ethane, 1,1,1-tris (diphenylphosphinomethyl) ethane, 1,1,1-tris (dimethylphosphinomethyl) Phosphorus-containing tridentate ligands such as ethane and 1,1,1-tris (diethylphosphinomethyl) ethane are exemplified.

Further, polydentate ligands having a heterocyclic group containing a Group 14, 15, 16 or 17 element of the periodic table include trifurylmethane and tris (5-methyl-2-
Furyl) methane, tris (5-ethyl-2-furyl) methane, tris (5-butyl-2-furyl) methane, 1,
Oxygen-containing tridentate ligands such as 1,1-trifurylethane, trifurylamine, trifurylphosphine, and trifurylphosphine oxide; sulfur-containing tridentate ligands such as tris (thienyl) methane; and tris (pyrazolyl) ) Methane, tris (3,5-dimethyl-1-pyrazolyl) methane, tris (3,5-diisopropyl-1-pyrazolyl) methane, tris (3,5-diphenyl-1-pyrazolyl) methane, 1,1,1 -Tris (3,5-dimethyl-1-pyrazolyl) ethane, 1,1,1-tris (3,5-dimethyl-1-pyrazolyl) propane, 1,1,1-tris (3,5-dimethyl-1) -Pyrazolyl) butane, tris (2-pyridyl) methane, tris (6-methyl-2-pyridyl) methane, tris (2-pyridyl) amine, tris (2-pyridyl) Sufin, tris (2-pyridyl) phosphine oxide, tris (2-pyridyl) hydroxymethyl methane, tris (1-imidazolyl) Motosan bidentate ligand such nitrogen such as methane and the like.

In the present invention, the halogen atom used for B in the above general formula (1) is not particularly limited, and examples thereof include a fluorine atom, a chlorine atom, a bromine atom and an iodine atom. The linear or branched alkyl group is not particularly limited, but examples include a methyl group, an ethyl group, a propyl group, a butyl group, a cyclohexyl group, a benzyl group, and a phenyl group.

Specific examples of the chromium complex represented by the above general formula (1) are not particularly limited. For example, tris (methoxymethyl) methanechromium trichloride (III), tris (methoxymethyl) Methane chromium (benzyl) dichloride (III), 1,1,1
-Tris (methoxymethyl) ethanechrome trichloride (III), 1,1,1-tris (ethoxymethyl)
Ethanechrome trichloride (III), 1,1,1-
Tris (butoxymethyl) ethanechrome trichloride (III), 1,1,1-tris (phenoxymethyl)
Ethanechrome trichloride (III), trifurylmethanechromium trichloride (III), 1,1,1-tris (methylthiomethyl) ethanechrome trichloride (III), 1,1,1-tris (dimethylaminomethyl) ethane Chromium trichloride (III), tris (pyrazolyl) methanechromium trichloride (II
I), tris (3,5-dimethyl-1-pyrazolyl) methanechrome trichloride (III), tris (3,5
-Dimethyl-1-pyrazolyl) methanechromium (hydrido) dichloride (III), tris (3,5-dimethyl-1-pyrazolyl) methanechrome (benzyl) dichloride (III), tris (3,5-dimethyl-1-pyrazolyl) ) Methanechromium (ethyl) dichloride (II
I), tris (3,5-dimethyl-1-pyrazolyl) methanechrome tribenzyl (III), 1,1,1-tris (3,5-dimethyl-1-pyrazolyl) ethanechrome trichloride (III), tris (3,5-diisopropyl-1-pyrazolyl) methanechrome trichloride (III), tris (3,5-diphenyl-1-pyrazolyl) methanechrome trichloride (III), tris (2-pyridyl) methanechrome trichloride ( II
I), tris (6-methyl-2-pyridyl) methanechrome trichloride (III), tris (2-pyridyl)
Amine chromium trichloride (III), tris (1-
Imidazolyl) methanechrome trichloride (II
I), 1,1,1-tris (dimethylphosphinomethyl) ethanechrome trichloride (III), 1,1,
Examples thereof include 1-tris (diphenylphosphinomethyl) ethanechrome trichloride (III) and 1,1,1-tris (diethylphosphinomethyl) ethanechrome trichloride (III).

From the viewpoint of catalytic activity, as the neutral polydentate ligand having a tripod-type structure represented by the general formula (1), nitrogen-containing tridentate ligands having a heterocyclic group are exemplified. Preferably, tris (3,5-dimethyl-1-pyrazolyl) methane is used. As B, a halogen atom is preferably used. Tris (3,5-dimethyl-1-pyrazolyl) methanechromium trichloride (III) or the like is used as a chromium complex to which a neutral polydentate ligand having a more preferable tripod-type structure is coordinated.

In the present invention, the method of synthesizing a chromium complex having the above-described neutral polydentate ligand having a tripod-type structure is not particularly limited. A known method for forming a complex from a compound [for example, Inor
g. Chem. , 25, 1080 (1986), etc.]. In this case, the chromium compound that can be used is not particularly limited,
For example, chromium (III) chloride, chromium (II) chloride,
Chromium (III) bromide, chromium (II) bromide, chromium (III) iodide, chromium (II) iodide, chromium (III) fluoride, chromium (II) fluoride, tris (tetrahydrofuran) chromium trichloride ( III), tris (1,4-dioxane) chromium trichloride (II
I), tris (diethyl ether) chromium trichloride (III), tris (pyridine) chromium trichloride (III), tris (acetonitrile) chromium trichloride (III) and the like.

The concentration of chromium metal when the above-mentioned polydentate ligand is reacted with a chromium compound to form a chromium complex is not particularly limited. The solvent used here is not particularly limited, but an organic solvent is preferably used. For example, pentane, hexane, heptane, octane, nonane, decane, cyclohexane, aliphatic hydrocarbons such as decalin, benzene, toluene, xylene,
Cumene, aromatic hydrocarbons such as trimethylbenzene, diethyl ether, ethers such as tetrahydrofuran,
Halogenated hydrocarbons such as methylene chloride, chloroform, carbon tetrachloride and the like can be mentioned. In addition, each of the above solvents can be used alone, or two or more of them can be used as a mixture.

The complex formation reaction is carried out at any temperature from -80 ° C to the boiling point of the reaction solvent used, preferably 20 to 200 ° C. When the complex formation reaction is performed at a temperature equal to or higher than the boiling point of the reaction solvent, it can be performed under pressure. The reaction time is not particularly limited, and is usually 1 minute to 48 hours,
Preferably it is 5 minutes to 24 hours. It is desirable that all operations during the reaction be performed while avoiding air and moisture. Further, it is preferable that the raw materials and the solvent are sufficiently dried.

As a separate synthesis method, an alkyl metal compound or a metal hydride compound is dissolved in a solvent using a chromium halide complex coordinated by a neutral polydentate ligand having a tripod-type structure synthesized by the above method as a raw material. The reaction may be performed to synthesize a chromium complex coordinated with a neutral polydentate ligand having a tripod-type structure according to the present invention.

The chromium complex to which the polydentate ligand is coordinated usually precipitates as a solid, and can be separated from the reaction solvent by filtration. Further, if necessary, washing is performed using the above-mentioned solvent, followed by drying to synthesize a chromium complex which is one of the components of the catalyst for trimerizing ethylene. If no precipitation occurs, precipitation can be performed by distilling off the solvent, adding a poor solvent, or cooling.

In the present invention, among the chromium complexes coordinated by a neutral polydentate ligand having a tripod-type structure, it is preferable to use a chromium complex in which the polydentate ligand is coordinating to a factor. By using a chromium complex in which a polydentate ligand is coordinated with a factor, effects such as suppression of by-product of polyethylene are recognized. Here, the complex in which the polydentate ligand is coordinated to “facial” refers to a complex in which the polydentate ligand is three-dimensional.
Is one of the isomers of a six-coordinate octahedral complex occupied by two coordination sites [Chemical Selection Organometallic Chemistry-Basics and Applications-,
143 (Shokabo)]. That is, in a six-coordinate octahedral complex in which three coordination sites are occupied by a multidentate ligand, the multidentate ligands are coordinated in an arrangement such that the three coordination sites are cis with respect to each other. Means you are.

The alkyl metal compound used in the present invention is not particularly limited. For example, the following general formula (4) R _p MX _q (4) (where p is 0 <p ≦ 3) , Q is 0 ≦ q <3, and p + q is 1 to 3. M represents lithium, magnesium, zinc, boron or aluminum, and R
Represents one or more selected from the group consisting of an alkyl group having 1 to 10 carbon atoms, and X represents one or more selected from the group consisting of a hydrogen atom, an alkoxide group, an aryl group and a halogen atom. Compounds represented by the formula (1) are preferred.

In the above general formula (4), the number of carbon atoms is 1 to 1.
The alkyl group of 0 is not particularly limited, and examples thereof include a methyl group, an ethyl group, a propyl group, a butyl group, a cyclohexyl group, and an octyl group. The alkoxide group is not particularly limited, but examples include a methoxide group, an ethoxide group, a butoxide group, and a phenoxide group. The aryl group is not particularly limited, but includes, for example, a phenyl group. The halogen atom is not particularly limited, but includes, for example, fluorine, chlorine, bromine and iodine.

In the general formula (4), M is A
l, when p and q are each 1.5, AlR _1.5 X _1.5
Becomes Although such compounds do not exist in theory, they are usually conventionally expressed as sesqui-forms of Al ₂ R ₃ X ₃ , and these compounds are also included in the present invention.

Examples of the alkyl metal compound represented by the general formula (4) include, for example, methyllithium, ethyllithium, propyllithium, n-butyllithium, sec.
-Butyl lithium, tert-butyl lithium, diethyl magnesium, ethyl butyl magnesium, ethyl chloro magnesium, ethyl bromo magnesium, dimethyl zinc, diethyl zinc, dibutyl zinc, trimethyl borane, triethyl borane, trimethyl aluminum, triethyl aluminum, tri-n-butyl aluminum,
Triisobutylaluminum, tri-n-hexylaluminum, tri-n-octylaluminum, tricyclohexylaluminum, dimethylethylaluminum, diethylaluminum hydride, diisobutylaluminum hydride, diethylaluminum ethoxide,
Diethylaluminum phenoxide, dicyclohexylphenylaluminum, ethylaluminum ethoxychloride, diethylaluminum chloride, diethylaluminum bromide, diisobutylaluminum chloride, dicyclohexylaluminum chloride, methylaluminum sesquichloride, ethylaluminum sesquichloride, butylaluminum sesquichloride, ethylaluminum dichloride, isobutylaluminum Dichloride and the like. Of these, trialkylaluminum compounds are preferably used from the viewpoint of availability and activity, and more preferably triethylaluminum, tri-n-butylaluminum, triisobutylaluminum, tri-n-hexylaluminum and tri-aluminum.
For example, n-octyl aluminum is used. These alkyl metal compounds can be used alone or in combination of two or more. The amount of the alkyl metal compound used is 0.1 to 1 mol per chromium complex.
10,000 equivalents, preferably 3 to 3000 equivalents,
More preferably, it is 5 to 2000 equivalents.

As the alkane compound used in the present invention, any hydrocarbon compound having 1 to 60 carbon atoms can be used without limitation. For example, butane, pentane, hexane, cyclopentane, cyclohexane, methylcyclohexane, cyclooctane, heptane, octane, nonane, decane, eicosane, tridecane, tetradecane, pentadecane, hexadecane and the like are preferable, and all of the structurally possible isomers thereof. Can be used. More preferred are hexane, cyclohexane, heptane, octane, nonane and decane. As for hexane, heptane, octane, nonane, and decane, all structurally possible isomers thereof can be used.

According to the present invention, an alkane compound used for preparing an ethylene trimerization catalyst obtained by contacting a chromium complex having a tripodal structure with a neutral polydentate ligand and an alkyl metal compound is 10 By the presence of at least the volume%, the catalytic activity is dramatically improved. In preparing the ethylene trimerization catalyst according to the present invention, an alkane compound and an aromatic hydrocarbon solvent such as, but not limited to, benzene, toluene, xylene, ethylbenzene, cumene, trimethylbenzene, chlorobenzene, and dichlorobenzene. And chlorinated hydrocarbon solvents such as methylene chloride, chloroform, carbon tetrachloride, dichloroethane and the like can be usually used together. Further, 1-hexene which is a main reaction product of the trimerization reaction can be used together with the alkane compound. Furthermore, in preparing the trimerization catalyst, as long as the alkane compound is contained in an amount of 10% by volume or more, two or more kinds of the above-mentioned aromatic hydrocarbon solvents and chlorinated hydrocarbon solvents can be used as a mixture. It is. Further, for the purpose of adjusting the concentration of the chromium complex during the ethylene trimerization reaction, it may be concentrated or diluted as necessary. The preferred amount of the alkane compound used is at least 10% by volume of the solution amount at the time of contact, more preferably 10 to 90% by volume, further preferably 10 to 80% by volume.

In the present invention, the ethylene trimerization reaction comprises
In the presence of the alkane compound, the chromium complex can be brought into contact with the alkyl metal compound in advance and then contacted with ethylene. The contacting method is not particularly limited.For example, in the presence of ethylene as a raw material for the trimerization reaction, a method of initiating the trimerization reaction by contacting a chromium complex with an alkyl metal compound in the presence of an alkane compound, or an alkane compound A chromium complex and an alkyl metal compound are brought into contact in advance in the presence of, followed by contact with ethylene to carry out a trimerization reaction. The order of mixing these is not particularly limited.

The concentration of the chromium complex in preparing the trimerization catalyst is not particularly limited, but is usually used at a concentration of 0.001 to 100 mmol, preferably 0.01 to 10 mmol per liter of the solvent. Is done. If the catalyst concentration is less than 0.001 micromolar, sufficient activity cannot be obtained. Conversely, if the catalyst concentration is greater than 100 mmol, the catalytic activity does not increase and it is not economical. The temperature at which the chromium complex is brought into contact with the alkyl metal compound in the presence of 10% by volume or more of the alkane compound is −100.
-250 ° C, preferably 0-200 ° C. The contact time is not particularly limited, and is 1 minute to 24 hours, preferably 2 minutes to
2 hours. It is desirable that all operations during contact be performed while avoiding air and moisture. It is preferable that the raw materials and the solvent are sufficiently dried.

The temperature of the ethylene trimerization reaction in the present invention is from -100 to 250 ° C., preferably from 0 to 2 ° C.
00 ° C. The reaction pressure is not particularly limited as long as the reaction system is in an ethylene atmosphere.
kg / cm ² , preferably 0.1 to 300 kg / cm ²
cm ² . The reaction time is usually from 5 seconds to 6 hours. Further, ethylene may be continuously supplied so as to maintain the above-mentioned pressure, or may be sealed at the above-mentioned pressure at the start of the reaction to cause a reaction. Ethylene as a raw material gas may contain a gas inert to the reaction, for example, nitrogen, argon, helium, or the like. It is desirable that all operations of the ethylene trimerization reaction be performed while avoiding air and moisture. Preferably, the ethylene is sufficiently dried.

In the present invention, the trimerization reaction of ethylene is
Batch, semi-batch, and continuous systems can be used. After the termination of the ethylene trimerization reaction, a deactivator such as, for example, water, alcohol, or an aqueous sodium hydroxide solution can be added to the reaction solution to stop the reaction. The deactivated waste chromium catalyst can be removed by a known deashing method, for example, extraction with water or an aqueous alkaline solution. The generated 1-hexene is separated from the reaction solution by a known extraction method or distillation method. In addition, polyethylene as a by-product can be separated and removed as a residue when a known centrifugal separation method or 1-hexene is separated by distillation at a reaction liquid outlet.

[0040]

EXAMPLES The present invention will be described in more detail with reference to the following Examples, which are only for illustrating the outline of the present invention and the present invention is not limited to these Examples.

IR measurement: IR was measured by a Nujol method using an infrared spectrophotometer (FTIR-8100) manufactured by Shimadzu Corporation.

Analysis by gas chromatography: The amount of the product having 4 to 8 carbon atoms contained in the reaction solution was determined by using a gas chromatograph (GC-14A) manufactured by Shimadzu Corporation equipped with a TC-1 column manufactured by GL Science. And analyzed. The analysis conditions were set at an injection temperature of 280 ° C. and a detector temperature of 280 ° C. using a nitrogen carrier, and n-heptane was used as an internal standard. The analysis was performed by injecting 1.0 μl of the reaction solution into the gas chromatograph and then raising the temperature of the column from 40 ° C. to 250 ° C.

The product having 10 or more carbon atoms was obtained from GL Science prepared separately from the above gas chromatograph.
The analysis was performed using a gas chromatograph (GC-14A) manufactured by Shimadzu Corporation equipped with a TC-1 column. The analysis was performed using a nitrogen carrier at an injection temperature of 300.
℃, detector temperature 300 ℃, n- as internal standard
Heptane was used. In the analysis, after injecting 1.5 μl of the reaction solution into this gas chromatograph, the temperature of the column was raised to 50 ° C.
From 300 ° C. to 300 ° C.

The products contained in the gas were analyzed using a gas chromatograph (GC-9A) manufactured by Shimadzu Corporation equipped with a column of Al ₂ O ₃ / KCl manufactured by Chrompack. The analysis conditions were as follows: using a nitrogen carrier, an injection temperature of 200 ° C., a detector temperature of 200 ° C., and a column temperature of 1 ° C.
The temperature was set at 20 ° C., and the absolute calibration method was used. The analysis was performed by injecting 0.2 ml of the recovered gas into the gas chromatograph.

Reference Example 1 A Schlenk tube having an inner volume of 100 ml Amer. C
hem. Soc. , 92, 5118 (1970). Tris (3,5-
126 mg of dimethyl-1-pyrazolyl) methane, tris (tetrahydrofuran) chromium trichloride (II
I) 143 mg and 20 ml of tetrahydrofuran were added,
The mixture was stirred under a nitrogen atmosphere for 12 hours. The generated crystals were separated by filtration to obtain tris (3,5-dimethyl-1-pyrazolyl) methanechrome trichloride (III) (IR (Nujol): 1565 cm ^-1 ). Hereinafter, this complex is referred to as complex A
Called.

Comparative Example 1 In a 150-ml glass pressure-resistant reaction vessel equipped with a thermometer and a stirrer, the complex A synthesized in Reference Example 1 and 80 ml of toluene were mixed and stirred. Next, a toluene solution of triisobutylaluminum was introduced. 1400
The temperature in the reaction vessel was raised to 80 ° C. while stirring at rpm, and the ethylene pressure in the reactor was increased to 5 kg / cm ² by gauge pressure.
, And the reaction was carried out for 30 minutes while maintaining these reaction conditions. Thereafter, water was pressurized into the reaction vessel with nitrogen to deactivate the catalyst and stop the reaction.

The reaction vessel was cooled to room temperature and then depressurized. No solid components such as polyethylene were found in the reaction solution. The products contained in the reaction solution and the recovered gas were analyzed by gas chromatography. Table 1 shows the results.

Examples 1-2 In a 150-ml glass pressure-resistant reaction vessel equipped with a thermometer and a stirrer, the complex A synthesized in Reference Example 1 and a solvent obtained by mixing n-hexane as an alkane compound with toluene were mixed. 80 ml of a toluene solution of triisobutylaluminum were introduced at room temperature. The temperature in the reaction vessel was raised to 80 ° C. while stirring at 1400 rpm, and ethylene was continuously introduced so as to maintain the ethylene pressure in the reactor at a gauge pressure of 5 kg / cm ² , while maintaining these reaction conditions. The reaction was performed for 30 minutes. Thereafter, water was pressurized into the reaction vessel with nitrogen to deactivate the catalyst and stop the reaction.

The reactor was cooled to room temperature and then depressurized. The products contained in the reaction solution and the recovered gas were analyzed by gas chromatography. Table 1 shows the results.

[0050]

[Table 1]

[0051]

According to the present invention, a chromium complex coordinated with a neutral polydentate ligand having a tripod-type structure is contacted with an alkyl metal compound in a solution containing 10% by volume or more of an alkane compound. The resulting ethylene trimerization catalyst is stable and easy to handle, and if it is used, 1-hexene can be produced efficiently and highly selectively from ethylene.

Continued on front page F-term (reference) 4G069 AA06 BA27A BA27B BC16A BC16B BC58A BC58B BE01A BE01B BE14A BE14B BE19A BE31A BE32A BE33A BE34A BE40A BE45A BE46A BE46B CB47 4H006 AA02 AC21 BA09 BA14 BA29 BA37 BA45 BA46

Claims (6)

[Claims] In a solution containing at least 10% by volume of an alkane compound, the following general formula (1) ACrB _n (1) (where n is an integer of 1 to 3; A has a tripod-type structure) A neutral polydentate ligand, Cr represents a chromium atom, B represents one or more selected from the group consisting of a hydrogen atom, a halogen atom, and a linear or branched alkyl group.) An ethylene trimerization catalyst obtained by contacting a chromium complex coordinated with a neutral polydentate ligand having a type structure with an alkyl metal compound. 2. A neutral polydentate ligand having a tripod-type structure,
The following general formula (2) (In the formula, j, k, and m are each independently an integer of 0 to 6. D ¹ is each independently a divalent hydrocarbon group which may have a substituent, and L ¹ is each independently And periodic table 1
It represents a substituent containing a Group 4, 15, 15 or 16 element. G ¹ is carbon or silicon, R ¹ is a hydrogen atom, an alkyl group having 1 to 10 carbon atoms or 6 to 10 carbon atoms.
Represents an aryl group. ) Or the following general formula (3): (Wherein a, b, and c are each independently an integer of 0 to 6, u is an integer of 0 or 1. D ² is each independently a divalent group which may have a substituent. A hydrocarbon group, 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 atom or a phosphorus atom, and R ² represents an oxygen atom or a sulfur atom. 2. The ethylene trimerization catalyst according to claim 1, which is a tridentate ligand represented by the formula: 3. The neutral polydentate ligand having a tripod-type structure is f
The ethylene trimerization catalyst according to claim 1 or 2, wherein a chromium complex coordinated with an acyl is used. 4. An alkyl metal compound represented by the following general formula (4): R _p MX _q (4) (where p is 0 <p ≦ 3, q is 0 ≦ q <3, and p + q Is 1 to 3. M represents lithium, magnesium, zinc, boron or aluminum;
Represents one or more selected from the group consisting of an alkyl group having 1 to 10 carbon atoms, and X represents one or more selected from the group consisting of a hydrogen atom, an alkoxide group, an aryl group and a halogen atom. 4. The catalyst for trimerizing ethylene according to claim 1, wherein the catalyst is a compound represented by the formula: 5. The ethylene trimerization catalyst according to claim 1, wherein the alkane compound is a hydrocarbon compound having 1 to 60 carbon atoms. 6. A process for trimerizing ethylene, comprising the step of trimerizing ethylene in the presence of the catalyst for trimerizing ethylene according to claim 1.