JPH1036431A - Ethylene trimerization catalyst and method for trimerizing ethylene therewith - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain an ethylene trimerization catalyst which can give 1-hexene useful as a comonomer for a linear low-density polyethylene at good efficiency by combining a specified chromium-containing solid substance with a pyrrole- containing compound and an alkylmetal compound. SOLUTION: This catalyst comprises a chromium-containing solid substance (A) which is obtained by impregnating an inorganic oxide with a chromium compound and calcining the product and in which the chromium compound is in the form of an oxide, a pyrrole-containing compound (B) and an alkylmetal compound (C). It is prepared by using components A, B and C as the starting materials and bringing them into contact with each other in a solvent. The temperature at which these three components are brought into contact with each other is -100 to 250 deg.C, desirably 0-200 deg.C. The time necessary to prepare the catalyst system is 0min to 24hr, desirably 0min to 2hr.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an ethylene trimerization catalyst comprising a chromium-containing solid substance, a pyrrole-containing compound and an alkyl metal compound, and a method for trimerizing ethylene using the same. More specifically, the present invention relates to an ethylene trimerization catalyst capable of efficiently producing 1-hexene useful as a raw material comonomer of linear low density polyethylene (LLDPE), and a method for trimerizing ethylene using the catalyst.

[0002]

2. Description of the Related Art It is known that a chromium-based catalyst is used in a process for producing 1-hexene by trimerizing ethylene. For example, Journal of Catalyst
sis, 47, 197 (1977) and JP-A-62-2.
No. 65237 discloses a catalyst system comprising a chromium compound, an aluminoxane and ether compounds such as dimethoxyethane. JP-A-6-239920 discloses a catalyst system comprising a chromium compound, a pyrrole-containing compound and an alkyl metal compound.
No. 2 discloses a catalyst system comprising a chromium compound, an imide compound and an alkyl metal compound.

[0003]

SUMMARY OF THE INVENTION However, Jou
rnal of Catalysis, 47, 197
(1977) and JP-A-62-265237, the catalyst activity is not sufficient, and the chromium-based catalyst is obtained by dissolving and mixing the catalyst raw material in a common aliphatic hydrocarbon solvent. Since it is a catalyst, it is essential that the chromium compound as a raw material can be dissolved in a solvent,
There is a problem that an expensive specific chromium compound such as chromium (III) tris (2-ethylhexanoate), chromium (III) tris (acetylacetonate), and chromium (IV) tetrabutoxide is required.

[0004] The methods described in JP-A-6-239920 and JP-A-8-59732 are excellent in that the catalytic activity is remarkably improved. There was a problem that an expensive chromium compound was required as described above. Further, since these catalysts are very unstable, their handling is not easy, and there are many problems in operation management such as a method for preparing a catalyst and storage stability of the catalyst.

On the other hand, as a chromium-based solid catalyst, JP-A-3-128904 discloses a product obtained by previously reacting a chromium complex having pyrrolide and an ether as a ligand with a metal alkyl or Lewis acid. Is supported on an inorganic oxide such as aluminophosphate. However, since the catalyst activity is low and a chromium complex having pyrrolide and ether as ligands is used as one component of the catalyst, the reaction step between the metal pyrrolide obtained from the pyrrole-containing compound and the chromium compound and the obtained chromium Not only is a complex isolation step required, the operation is complicated, but the chromium complex having pyrrolide and ether as ligands is extremely unstable to oxygen and moisture, so its handling is not easy. There was no problem.

The present invention has been made in view of the above-mentioned problems, and an object of the present invention is to provide an LLD by trimerizing ethylene.
An object of the present invention is to provide an industrially advantageous catalyst system which can efficiently produce 1-hexene, which is useful as a raw material comonomer for PE, can be prepared from an inexpensive Cr raw material, and is easy to handle. In addition, the present invention relates to a method for trimerizing ethylene using the above-mentioned catalyst for trimerizing ethylene.

[0007]

Means for Solving the Problems The present inventors have made intensive studies to solve the above-mentioned problems. As a result, they have found that when the ethylene trimerization reaction is carried out using a specific chromium-containing solid material and a catalyst comprising a pyrrole-containing compound and an alkyl metal compound, the trimerization reaction proceeds with extremely high activity, and the present invention has been completed. I came to.

That is, the present invention provides a chromium-containing solid substance obtained by supporting (A) a chromium compound on an inorganic oxide and then calcining the chromium compound, wherein the supported chromium compound forms an oxide. The present invention relates to an ethylene trimerization catalyst comprising a chromium-containing solid substance, (B) a pyrrole-containing compound and (C) an alkyl metal compound, and a method for trimerizing ethylene in the presence of the catalyst.

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

The chromium-containing solid substance used in the present invention is a solid substance called "Philips catalyst" which is widely known as a medium-pressure ethylene polymerization catalyst.
It can be obtained by supporting a chromium compound on an inorganic oxide and then firing. An example of this Phillips catalyst is Journal of Catalysis, 7
7, 348 (1982), ibid, 82, 98 (19
83), ibid, 83, 346 (1983), Adv
canceled in Catalysis, 38, 47
(1985), which are helpful for the present invention. Generally, the chromium of the Phillips catalyst is in an oxide state in which at least a part of the chromium has hexavalent valence.

In the present invention, a chromium-containing solid substance for use as a polymerization catalyst for ethylene, that is, a known Phillips catalyst which is easy to handle and is easily available, is combined with a pyrrole-containing compound and an alkyl metal compound described below to obtain ethylene. It would be very interesting to be able to be an active catalyst for the ethylene trimerization instead of the polymerization of ethylene. Further, since the chromium-containing solid substance is insoluble in the reaction solvent, there are also advantages such as easy separation and removal of the catalyst.

The inorganic oxide of the present invention is not particularly limited, but examples thereof include inorganic oxides such as silica, alumina, titania, zirconia, magnesia, tin oxide, silica alumina, zeolite, clay minerals, and mixtures thereof. Products, halogen-modified inorganic oxides such as fluorinated alumina, and phosphorus-containing inorganic compounds such as alumina phosphate, phosphate silica, and those obtained by treating alumina with phosphoric acid and calcining the same. Among these, silica is preferably used from the viewpoint of catalytic activity and availability.

The chromium compound is not particularly limited. For example, alkylated chromium, arene complex, alcoholate, β-diketonate salt, β-diketonate
Examples include ketoesters, amidates, halides, oxyhalides, carboxylates, nitrates, sulfates, perchlorates, carbonylates, oxides and the like. Specifically, chromium (III) tris (η- Allyl), dichromium (II) tetrakis (η-allyl), chromium (IV)
Tetrakis (trimethylsilylmethyl), chromium (0)
Bis (benzene), chromium (IV) tetraethoxide,
Chromium (IV) tetrapropoxide, chromium (IV) tetrabutoxide, chromium (III) tris (acetylacetonate), chromium (III) tris (trifluoroacetylacetonate), chromium (III) tris (hexafluoroacetylacetonate) ), Chromium (II
I) Tris (2,2,6,6-tetramethyl-3,5-
Heptane dionate), chromium (III) tris (1,
3-butane dionate), chromium (III) tris (2
-Methyl-1,3-butanedionate), chromium (II
I) Tris (benzoylacetonate), chromium (II)
I) Tris (acetyl acetate), chromium (III)
Tris (dimethylamide), chromium (III) tris (dicyclohexylamide), chromium (I) fluoride, chromium (II) fluoride, chromium (II) chloride, chromium (II) chloride, chromium (II) bromide, chromium (II) bromide, Chromic iodide, chromic iodide, chromyl chloride, chromium (III) tris (acetate), chromium (III) tris (propionate), chromium (III) tris (butyrate), chromium (III) tris (2- Ethyl hexanoate), chromium (III) tris (isooctanoate), chromium (III) tris (oxy-2-ethylhexanoate), chromium (III) tris (neopentanoate), chromium (III) tris (Laurate), chromium (III) tris (stearate), chromium (III)
Tris (oleate), chromium (II) bis (oleate), chromium (III) tris (benzoate), chromium (III) tris (naphthenate), chromium nitrate, chromium sulfate, chromium perchlorate, chromium hexacarbonyl,
Chromium trioxide, potassium dichromate, ammonium chromate, di-tert-butyl chromate and the like can be mentioned. Of these, chromium oxides and acetates are preferably used in terms of ease of handling and economy, and more preferably chromium trioxide or chromium acetate is used. The chromium compounds can be used alone or in combination of two or more.

The chromium compound can be supported on the inorganic oxide by a known method such as impregnation, ion exchange, coprecipitation, deposition, kneading, or sublimation. An appropriate method may be used depending on the type of the oxide. The amount of chromium to be supported is 0.01 to 10% by weight, preferably 0.1 to 5% by weight, more preferably 0.3 to 3% by weight of chromium atoms based on the inorganic oxide.
% By weight.

In the present invention, the chromium compound-supported inorganic oxide thus obtained is further calcined to obtain the chromium-containing solid substance of the present invention. The atmosphere at the time of firing is not particularly limited, for example, oxygen,
It is a gas atmosphere of nitrogen, argon, helium or the like, preferably in an atmosphere containing oxygen, and more preferably in air. When firing in an atmosphere containing oxygen,
The supported chromium compound easily forms an oxide, and at least a part of the oxide tends to be in a hexavalent state.

The temperature conditions during firing are not particularly limited, but are 400 to 1000 ° C., preferably 500 to 9 ° C.
Perform at 00 ° C. When the calcination temperature is lower than 400 ° C., the supported chromium compound does not form an oxide, or even if formed, a part of the oxide does not convert to the hexavalent state, and the activity constituting the ethylene trimerization catalyst Chromium-containing solid material cannot be obtained. On the other hand, if the calcination temperature exceeds 1000 ° C., the inorganic oxide used for preparing the chromium-containing solid substance is deteriorated, and an active chromium-containing solid substance cannot be obtained. The firing time is 5 minutes to 100 minutes.
Time, preferably 30 minutes to 10 hours. It is desirable that all operations of baking are performed while avoiding moisture, and it is more preferable that the firing is performed in a fluidized state.

In the chromium-containing solid material of the present invention thus prepared, the supported chromium compound forms an oxide, and at least a part of the chromium oxide is in a hexavalent state, and furthermore, chromium is an inorganic oxide. It has a structure immobilized by a chemical bond with a substance, which is an important feature as a component of the ethylene trimerization catalyst described later.

In the present invention, the chromium-containing solid substance prepared as described above is further treated, if desired, under a reducing atmosphere. By the treatment in a reducing atmosphere, the ethylene trimerization catalyst described below has effects such as further improving the catalytic activity.

Here, the treatment in a reducing atmosphere means that the chromium-containing solid substance is exposed to a reducing atmosphere.
For example, it refers to treating a chromium-containing solid substance in a gas phase or a liquid phase in the presence of a reducing gas. The reducing gas is not particularly limited as long as it has a reducing property, and examples thereof include carbon monoxide, hydrogen, and olefins such as ethylene and propylene.

As the treatment under a reducing atmosphere, in the gas phase treatment, a baking treatment under a flow of a reducing gas may be mentioned. The firing conditions are not particularly limited,
Temperature is 200-500 ° C, preferably 250-450 ° C
And the time is 5 minutes to 100 hours, preferably 30 minutes to
Perform for 10 hours. Further, the pressure during the reduction treatment is not particularly limited. When firing, use a sufficiently dry reducing gas.
It is preferable to carry out the process under flowing conditions.

In the liquid phase treatment, the chromium-containing solid substance is suspended in a suitable organic solvent and mixed under a reducing gas. The mixing conditions are not particularly limited, but the temperature is 0 to 300 ° C, preferably 50 to 200 ° C, and the time is 5 minutes to 100 hours, preferably 30 minutes to 10 hours. The pressure during the reduction treatment is not particularly limited, but is usually 0 to 0 in absolute pressure.
100 kg / cm ² , preferably 0 to 70 kg / cm ²
cm ² . The reducing gas may include a gas inert to the reduction treatment, for example, nitrogen, argon, helium, or the like. In addition, it is desirable that all operations of the treatment under the reducing atmosphere be performed while avoiding air and moisture.
Under these conditions, at least a part of the hexavalent chromium contained in the chromium-containing solid substance is reduced to a lower valence state, and the above-mentioned effect is exhibited.

The ethylene trimerization reaction conditions described below are under a reducing atmosphere due to the presence of ethylene.
Therefore, the chromium-containing solid material, which is a component of the ethylene trimerization catalyst, is substantially exposed to a reducing atmosphere, and at least a part of the hexavalent chromium contained in the chromium-containing solid material is less than that. Reduced to a lower valence state. Therefore, high catalytic activity can be exhibited without necessarily performing the reduction treatment.

The pyrrole-containing compound used in the present invention may be any compound having a pyrrole ring structure, for example, pyrrole, 2,5-dimethylpyrrole, 3,4-dimethylpyrrole, 2,4-dimethylpyrrole. Dimethyl-3-ethylpyrrole, 3,4-dichloropyrrole, 2,3,4,5-tetrachloropyrrole, 2-acetylpyrrole, 3-acetyl-2,4-dimethylpyrrole, pyrrole-2-carboxylic acid, pyrrole Pyrroles such as -2-carboxaldehyde, ethyl-2,4-dimethyl-5- (ethoxycarbonyl) -3-pyrrole-propionate, ethyl-3,5-dimethyl-2-pyrrolecarboxylate, tetrahydroindole, lithium Pyrrolide, sodium pyrrolide, potassium pyrrolide, cesium pyrrolide, Chill aluminum pyrrolide, ethylaluminum pyrrolide, aluminum tri pyrrolide, diisobutylaluminum pyrrolide, sodium -
2,5-dimethylpyrrolide, potassium-2,5-dimethylpyrrolide, cesium-2,5-dimethylpyrrolide, diethylaluminum-2,5-dimethylpyrrolide, ethylaluminum bis (2,5-dimethylpyrrolide ), Aluminum tris (2,5-dimethylpyrrolide) and metal pyrrolides such as diisobutylaluminum-2,5-dimethylpyrrolide. Of these, pyrroles are preferably used in terms of catalytic activity and availability, and more preferably pyrrole or 2,5-dimethylpyrrole is used. These pyrrole-containing compounds can be used alone or in combination of two or more. Further, the pyrrole-containing compound may be positively added at the time of preparing the catalyst, or may be generated in the system at the time of preparing the catalyst.

The pyrrole-containing compound is used in an amount of 0.1 to 1 mol of chromium atoms contained in the chromium-containing solid substance.
1 to 1,000 molar equivalents, preferably 0.5 to 5
It is 00 molar equivalent, more preferably 1 to 300 molar equivalent. If the amount of the pyrrole-containing compound is less than 0.1 mole equivalent per mole of chromium atom, sufficient trimerization activity cannot be obtained, and a large amount of polymer is produced as a by-product. On the other hand, if the amount used exceeds 1,000 molar equivalents per mole of the chromium compound, the catalytic activity tends to decrease, which is not economically preferable.

The alkyl metal compound used in the present invention is not particularly limited. For example, the following general formula (1) R _p MX _q (1) (where p is a number satisfying 0 <p ≦ 3) And q is a number of 0 ≦ q <3, and p + q is a number of 1 to 3. M represents lithium, magnesium, zinc, boron or aluminum, and R represents an alkyl having 1 to 10 carbons. And X represents one or more selected from the group consisting of a hydrogen atom, an alkoxy group, an aryl group and a halogen atom), or an aluminoxane. Can be

In the above general formula (1), the number of carbon atoms is 1 to 1
The alkyl group of 0 is not particularly limited, and includes, for example, a methyl group, an ethyl group, a propyl group, a butyl group, a cyclohexyl group, an octyl group, and the like. Although it does not specifically limit as an alkoxy group, For example, a methoxy group, an ethoxy group, a butoxy group, a phenoxy group, etc. are mentioned. As the aryl group,
Although not particularly limited, for example, a phenyl group and the like can be mentioned. Although it does not specifically limit as a halogen atom, For example, fluorine, chlorine, bromine, or iodine is mentioned.

In the above general formula (1), 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 (1) include methyl lithium, ethyl lithium, propyl lithium, n-butyl lithium, s-butyl lithium, t-butyl lithium, diethyl magnesium, and ethyl butyl magnesium. , Ethyl chloro magnesium, ethyl bromo magnesium, dimethyl zinc, diethyl zinc, dibutyl zinc, trimethyl borane, triethyl borane, trimethyl aluminum, triethyl aluminum, triisobutyl aluminum, tri-n-hexyl aluminum, tri-n-octyl aluminum, tricyclohexyl Aluminum, dimethylethylaluminum, diethylaluminum hydride, diisobutylaluminum hydride, diethylaluminum ethoxide, diethyl Rumi bromide phenoxide, dicyclohexyl phenyl aluminum, ethyl aluminum ethoxy chloride, diethylaluminum chloride, diethylaluminum bromide, diisobutylaluminum chloride, dicyclohexyl aluminum chloride,
Examples include methylaluminum sesquichloride, ethylaluminum sesquichloride, butylaluminum sesquichloride, ethylaluminum dichloride, isobutylaluminum dichloride and the like.

The aluminoxane used in the present invention is a hydrolysis product obtained by reacting the above-mentioned alkylaluminum compound with water in a quantitative ratio within a certain range. The method for hydrolyzing the alkylaluminum compound is not particularly limited, and can be synthesized by a known method. For example, (1) a method in which water is brought into contact with an alkyl aluminum compound as it is or a diluted solution of an organic solvent, (2) an alkyl aluminum compound and magnesium chloride hexahydrate, iron sulfate heptahydrate, copper sulfate pentahydrate. For example, a method of reacting with water of crystallization of a metal salt. Specifically, Japanese Patent Application Laid-Open Nos. Sho 62-265237 and
It is disclosed in Japanese Patent Application Laid-Open No. 2-148491. The molar ratio of the alkylaluminum compound to water during the hydrolysis is 1: 0.4 to 1: 1.2, preferably 1: 0.5 to 1:
1.0.

Of these alkyl metal compounds, triethylaluminum and triisobutylaluminum are preferably used in view of availability and activity. Not only can these alkyl metal compounds be used alone,
It is also possible to use a mixture of two or more.

The amount of the alkyl metal compound used is 0.1 to 1 mole of chromium atoms contained in the chromium-containing solid substance.
10 to 10,000 molar equivalents, preferably 3 to 3,0
00 molar equivalent, more preferably 10 to 2,000 molar equivalent.

The ethylene trimerization catalyst of the present invention can be prepared by bringing the above-mentioned chromium-containing solid substance, pyrrole-containing compound and alkyl metal compound into contact with each other in a solvent. The contacting method is not particularly limited.For example, a catalyst is prepared by contacting a chromium-containing solid substance, a pyrrole-containing compound, and an alkyl metal compound in the presence of ethylene, which is a trimerization reaction raw material, and the trimerization reaction is started simultaneously with the contact. Or a method in which a chromium-containing solid substance, a pyrrole-containing compound and an alkyl metal compound are brought into contact in advance to prepare a catalyst, and then contacted with ethylene to carry out a trimerization reaction. Specifically, in the former case, (1) a chromium-containing solid substance, an alkyl metal compound,
(2) introducing a chromium-containing solid substance, a pyrrole-containing compound and ethylene into a solution containing an alkyl metal compound, and (3) introducing a pyrrole-containing compound and pyrrole into a solution containing an alkyl metal compound. (4) introducing a chromium-containing solid substance and ethylene into a solution containing an alkyl metal compound and a pyrrole-containing compound, and (5) introducing a chromium-containing solid substance into a solution containing an alkyl metal compound and a pyrrole-containing compound. The catalyst can be prepared by a method such as introducing an alkyl metal compound, a pyrrole-containing compound and ethylene into the suspension. In the latter case, (1) an alkyl metal compound is introduced into a suspension containing a chromium-containing solid substance and a pyrrole-containing compound, and (2) a chromium-containing solid substance is introduced into a solution containing the alkyl metal compound and a pyrrole-containing compound. (3) introducing a chromium-containing solid substance and a pyrrole-containing compound into a solution containing an alkyl metal compound;
(4) A catalyst can be prepared by a method of introducing a pyrrole-containing compound and an alkyl metal compound into a suspension containing a chromium-containing solid substance. The order of mixing these raw materials is not particularly limited.

The amount of the chromium-containing solid substance used in preparing the catalyst system is not particularly limited, but is usually 0.001 micromol to 1 liter of the solvent in terms of chromium atoms contained in the chromium-containing solid substance. 100 mmol,
Preferably, it is used at a concentration of 0.01 micromolar to 10 millimolar. As the solvent used here, for example, butane, pentane, hexane, heptane, octane, isooctane, nonane, decane, cyclopentane,
Aliphatic hydrocarbons such as cyclohexane, methylcyclohexane, cyclooctane, and decalin; aromatic hydrocarbons such as benzene, toluene, xylene, ethylbenzene, cumene, chlorobenzene, and dichlorobenzene; methylene chloride; chloroform; carbon tetrachloride; dichloroethane; Chlorinated hydrocarbons. Reaction products and by-products, for example, olefins such as 1-hexene and decene can also be used as the solvent. These solvents can be used alone or in combination of two or more. Here, for the purpose of controlling the catalyst concentration at the time of preparing the catalyst, it may be concentrated or diluted as necessary.

The temperature at which the chromium-containing solid substance, the pyrrole-containing compound and the alkyl metal compound are brought into contact is -100 to 250 ° C, preferably 0 to 200 ° C.
The preparation time of the catalyst system is not particularly limited, and is 0 minute to 24 hours,
Preferably it is 0 minutes to 2 hours. It is desirable that all operations for preparing the catalyst be performed while avoiding air and moisture. Further, it is preferable that the catalyst preparation raw material and the solvent are sufficiently dried.

According to the present invention, a halide is further added to a catalyst system comprising a chromium-containing solid substance, a pyrrole-containing compound and an alkali metal compound prepared as described above, and the resulting catalyst is used as an ethylene trimerization catalyst. Effects such as improvement of catalytic activity and suppression of by-product of polymer are recognized by the coexistence of halide.

The halide used in the present invention is not particularly limited. For example, the following general formula (2) R ′ _i M ′ _j X ′ _k (2) (where i is 0 to 4) And j is an integer of 0 to 1 and k is an integer of 1 to 4. R ′ represents hydrogen or a hydrocarbon having 1 to 20 carbon atoms, and M ′ represents I of the periodic table.
Compounds represented by A, IIA, VIII, IIB, IIIB, IVB or VB group, and X ′ represents at least one or more selected from halogen atoms) are preferred.

Examples of the halide of the general formula (2) include, for example, chlorine, bromine, iodine, butyl chloride, amyl chloride, hexyl chloride, heptyl chloride, octyl chloride, nonyl chloride, decyl chloride, lauryl chloride, methyl bromide, propyl Bromide, butyl bromide, amyl bromide, hexyl bromide, ethylhexyl bromide, nonyl bromide, cetyl bromide, dibromomethane, dichloroethane, dibromoethane, dichlorobutene, cyclohexyl bromide, chloroform, tetrachlorohydrocarbon, chlorobenzene, dichlorobenzene, bromobenzene, dibromobenzene , Sodium chloride, potassium chloride, cesium chloride, magnesium chloride, zinc chloride, zinc bromide, zinc iodide, boron trichloride,
Boron tribromide, aluminum trichloride, aluminum tribromide, silicon tetrachloride, germanium tetrachloride, germanium tetrabromide, stannous chloride, stannic chloride, tin iodide, phosphorus trichloride, phosphorus pentachloride, trichloride Antimony chloride, antimony pentachloride, antimony tribromide, antimony trifluoride, antimony pentafluoride, dimethylaluminum chloride, dimethylaluminum bromide, dimethylaluminum iodide, diethylaluminum chloride, diethylaluminum bromide, diethylaluminum iodide, ethylaluminum Dichloride, ethylaluminum dibromide, ethylaluminum diiodide, diisopropylaluminum chloride, diisobutylaluminum chloride, isobutylaluminum dichloride, dihexylal Nium chloride, dicyclohexyl aluminum chloride, dioctyl aluminum chloride, methyl aluminum sesquichloride, ethyl aluminum sesquichloride, butyl aluminum sesquichloride, trimethylsilyl chloride, trimethylsilyl bromide, dimethylsilyl dichloride, methylsilyl trichloride, phenylsilyl trichloride, diphenylsilyl dichloride, Examples include methyldichlorosilane, tributyltin chloride, dibutyltin dichloride, butyltin trichloride, triphenyltin chloride, diphenyltin dichloride, and phenyltin trichloride. Of these, chlorinated products are preferably used from the viewpoint of ease of handling and economy, and more preferably, diethyl aluminum chloride, ethyl aluminum dichloride, stannic chloride, germanium tetrachloride, and antimony pentachloride are used. These halides can be used alone, or two or more of them can be used in combination.

The halide may be added at the time of preparing a catalyst comprising a chromium-containing solid substance, a pyrrole-containing compound and an alkyl metal compound, or may be directly added to an ethylene trimerization reaction system. The amount of the halide to be used is 0.2 to 5,000 molar equivalents, preferably 0.5 to 2,000 molar equivalents, more preferably 0.5 to 2,000 molar equivalents, per mole of chromium atoms contained in the chromium-containing solid substance. 1 to 1,000 molar equivalents.

According to the present invention, a Lewis acid is further added to a catalyst system comprising a chromium-containing solid substance, a pyrrole-containing compound and an alkyl metal compound prepared as described above,
It is used as a catalyst for trimerizing ethylene. The effect of improving the catalytic activity is recognized by the coexistence of the Lewis acid.

The Lewis acid used in the present invention is not particularly limited. For example, the following general formula (3): M (Ar) _l (3) (where l is an integer of 2 to 4) , M is the Periodic Table II
A compound represented by group B, IIIB or IVB, and Ar represents at least one selected from aryl groups).

Examples of the Lewis acid of the general formula (3) include tris (2-fluorophenyl) boron, tris (3-fluorophenyl) boron, tris (4-fluorophenyl) boron, tris (2,4-difluoro) Phenyl) boron, tris (2,5-difluorophenyl)
Boron, tris (2,6-difluorophenyl) boron, tris (2,4,5-trifluorophenyl) boron, tris (2,4,6-trifluorophenyl) boron, tris (pentafluorophenyl) boron, tris [3,5-bis (trifluoromethyl) phenyl] boron, bis (pentafluorophenyl) zinc, tris (pentafluorophenyl) aluminum, tetrakis (pentafluorophenyl) germanium, tetrakis (pentafluorophenyl) tin, tris (4 -Trifluoromethylphenyl) boron and the like. Of these, tris (pentafluorophenyl) boron is preferably used in terms of availability and activity. These Lewis acids can be used alone or in combination of two or more. It is also possible to use a mixture with the above halide.

The Lewis acid may be added during the preparation of a catalyst comprising a chromium-containing solid substance, a pyrrole-containing compound and an alkyl metal compound, or may be added directly to the ethylene trimerization reaction system. The amount of the Lewis acid used is 0.1 to 2,000 molar equivalents, preferably 0.5 to 1,500 molar equivalents, and more preferably 1 mol of chromium atom contained in the chromium-containing solid substance. 1 to 1,000 molar equivalents. If the amount of the Lewis acid used is less than 0.1 molar equivalent per 1 mole of chromium atom, sufficient ethylene trimerization activity cannot be obtained. On the other hand, if the amount used exceeds 2,000 molar equivalents per mole of chromium atoms, the catalytic activity does not increase and is not economically preferable.

The ethylene trimerization reaction is carried out using the ethylene trimerization catalyst thus prepared. In the present invention, the use amount of the chromium-containing solid substance is not particularly limited, but is usually 0.001 micromol in terms of chromium atoms contained in the chromium-containing solid substance per liter of the trimerization reaction solution suspended in the solvent. It is used at a concentration of .about.100 mmol, preferably 0.01 .mu.mol to 10 mmol. If the catalyst concentration is lower than this, sufficient activity cannot be obtained. Conversely, if the catalyst concentration is higher than this, catalyst activity does not increase and it is not economical.

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. Reaction pressure is 0 to 3,000k in absolute pressure
g / cm ² , preferably 0 to 300 kg / cm ² . The reaction time depends on the temperature and the pressure and cannot be determined unconditionally, but is usually 5 minutes 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, which is 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 trimerization reaction be performed while avoiding air and moisture. Further, it is preferable that ethylene is sufficiently dried.

This reaction can be carried out in any of a batch system, a semi-continuous system and a continuous system. After the completion of the trimerization reaction, unreacted ethylene is separated, and then the reaction is terminated by adding a deactivator such as, for example, water, alcohol, or an aqueous solution of sodium hydroxide. The deactivated chromium-containing solid component is removed by a known separation method, for example, centrifugation or the like.
Hexene is separated from the reaction solution by a known extraction method or distillation method. Further, the by-produced polymer is separated and removed at the outlet of the reaction solution as a residue in a known centrifugal separation method or distillation separation of 1-hexene.

[0046]

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. . Example 1 A 100 ml glass flask was charged with silica (surface area: 300
m ² / g, pore volume 1.6 ml / g, calcined at 300 ° C. for 5 hours), and 20 g of chromium acetate aqueous solution was added to silica such that the weight of chromium atoms became 1.0% by weight. The mixture was stirred and mixed at room temperature for 1 hour. The suspension was evaporated to dryness to obtain a solid material impregnated with chromium acetate (hereinafter, this solid material is referred to as Cr-1).

5 g of this solid substance was packed in a quartz tube,
A chromium-containing solid substance was obtained by performing a calcination treatment at a temperature of 5 ° C. for 5 hours in a flowing air (hereinafter, this solid substance is referred to as Cr-2). The quantitative analysis of organic substances contained in this solid
The analysis was carried out by an N analyzer, but no organic matter was contained.

A 1-L stainless steel pressure-resistant reaction vessel equipped with a thermometer, a catalyst feed tube and
After vacuum drying under heating at ℃, the atmosphere was sufficiently replaced with nitrogen gas. 50 mg of the above-mentioned chromium-containing solid substance (Cr-2), 0.27 ml of a 0.368 mol / L pyrrole / cyclohexane solution, and 350 ml of dried cyclohexane were charged into the body of the reaction vessel. On the other hand, 11
5.4 ml of a 2 mmol / L triisobutylaluminum / cyclohexane solution and dried cyclohexane 50
ml.

While maintaining the reaction vessel at 120 ° C., the stirring speed was adjusted to 1,000 rpm, ethylene was introduced into the catalyst feed tube, and a triisobutylaluminum / cyclohexane solution was introduced into the reaction vessel body by ethylene pressure. Started trimerization of ethylene. Ethylene gas was blown in so that the absolute pressure in the reaction vessel became 40 kg / cm ^2, and thereafter, introduction was continued so as to maintain the pressure, and a reaction was carried out for 30 minutes while maintaining these reaction conditions.
After 30 minutes, the reaction was stopped by injecting an aqueous sodium hydroxide solution into the reaction vessel with nitrogen to deactivate the catalyst.

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. Also, the solid content contained in the reaction solution was filtered off using a filter paper, and after air-drying,
It was dried under reduced pressure (1 mmHg, 100 ° C.) and its weight was measured. Table 1 shows the results.

Example 2 The 112 mmol / L triisobutylaluminum / cyclohexane solution was replaced with 6.1 ml, and
1 / L germanium tetrachloride / cyclohexane solution
The reaction was carried out in the same manner as in Example 1, except that 0 ml was further added to the catalyst feed tube. Table 1 shows the results.

Comparative Example 1 In the ethylene trimerization reaction, the reaction was carried out in the same manner as in Example 1 except that the pyrrole-containing compound was not used. Table 1 shows the results.

[0053]

[Table 1]

[0054]

According to the present inventors, a chromium-containing solid substance obtained by supporting a chromium compound on an inorganic oxide and then calcining the chromium compound forms an oxide, When a trimerization reaction of ethylene is carried out using a catalyst comprising a chromium-containing solid substance, a pyrrole-containing compound and an alkyl metal compound, at least a part of the oxide of Along with performing the quantification reaction,
The chromium component of the used catalyst can be easily removed.

Claims (3)

[Claims] 1. A chromium-containing solid substance obtained by supporting (A) a chromium compound on an inorganic oxide and then calcining, wherein the chromium compound supported forms an oxide. And (B) a pyrrole-containing compound and (C) an alkyl metal compound. 2. An alkyl metal compound represented by the following general formula (1): R _p MX _q (1) (where p is a number satisfying 0 <p ≦ 3, q is a number satisfying 0 ≦ q <3, and And p + q is a number from 1 to 3. M represents lithium, magnesium, zinc, boron or aluminum, R represents at least one selected from an alkyl group having 1 to 10 carbon atoms, and X represents a hydrogen atom. , An alkoxy group, an aryl group and a halogen atom), or an aluminoxane. 3. The ethylene trimerization catalyst according to claim 1, wherein 3. A method for trimerizing ethylene, wherein ethylene is trimerized in the presence of the catalyst for trimerizing ethylene according to claim 1 or 2.