JPH08239331A - Production of alpha-olefin oligomer - Google Patents

Abstract

PURPOSE: To obtain an α-olefin oligomer in high yield and selectivity by allowing an α-olefin to react with a specific chromium catalyst in a solvent and adding specific components to the recovered solvent containing catalyst components to readily reactivate the catalyst. CONSTITUTION: Using, as a chromium catalyst, a catalyst system comprising (a) a chromium compound such as chromium (III) 2-ethylhexanoate; (b) at least one selected from amines, amides and imides such as 2,5-dimethylpyrrol, (c) an alkylaluminum such as triethylaluminum, and (d) a halogen-containing compound such as tetrachloroethane, the catalyst components containing at least (c) and (d) selected from (b) through (d) are heated over 100 deg.C in a solvent such as heptane, an α-olefin is reacted in a solvent such as n-heptane at 0-250 deg.C under normal pressure to 250kg/m<2> for 1 minute to 20 hours. The α-olefin oligomer is distilled off from the reaction mixture and the components selected from an alkylating agent, a reducing agent and a halogen-containing agent are added to the recovered solvent containing the catalyst components to circulate these components. The molar ratio of the catalyst components is a:b:c:d=1:(0.1-10):(1-100):(0.1-20).

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for producing an α-olefin low polymer, and more particularly, to a high yield of an α-olefin low polymer mainly composed of ethylene and 1-hexene. The present invention relates to a method for producing an industrially advantageous α-olefin low polymer which can be produced with a high selectivity.

[0002]

2. Description of the Related Art Conventionally, as a method for low polymerization of α-olefin such as ethylene, there has been known a method of using a chromium-based catalyst comprising a combination of a specific chromium compound and a specific organoaluminum compound. For example, Japanese Patent Publication No.
No. 8707 describes a method for obtaining 1-hexene from ethylene with a catalyst system consisting of a Group VIA transition metal compound containing chromium and polyhydrocarbyl aluminum oxide.

Further, in JP-A-3-128904, α-olefin is trimerized by using a catalyst obtained by previously reacting a chromium-containing compound having a chromium-pyrrolyl bond with a metal alkyl or Lewis acid. How to do is described.

[0004]

By the way, in the industrial production method of α-olefin low polymer, it is important to enhance the utilization efficiency of the catalyst. For example, the reaction system is activated by activating the catalyst by a simple operation. However, no proposal is made in any of the above publications.

The present invention has been made in view of the above circumstances, and an object thereof is a method for producing an α-olefin low polymer using a chromium-based catalyst, in which the catalyst is activated by a simple operation to react. In particular, the production of an industrially advantageous α-olefin low polymer capable of producing an α-olefin low polymer mainly composed of 1-hexene from ethylene in a high yield and a high selectivity by circulating the system into the system. To provide a method.

[0006]

Means for Solving the Problems The present inventors can easily activate a catalyst by adding a specific component to the recovered solvent containing a catalyst component, and further, to add the activated catalyst. It was found that there is no effect on the reaction system even if the components are circulated to the reaction system.

The present invention has been achieved on the basis of the above findings, and the gist thereof is α-using a chromium-based catalyst.
In the method for producing an olefin low polymer, as a chromium-based catalyst, at least one compound (b) selected from the group consisting of a chromium compound (a), an amine, an amide and an imide, an alkylaluminum compound (c) and a halogen-containing compound are contained. Using a catalyst system consisting of a combination of the compounds (d), low polymerization of α-olefin is carried out in a solvent, the α-olefin low polymer is distilled off from the obtained reaction solution, and then the recovered catalyst component is used. A method for producing an α-olefin low polymer, which comprises adding at least one component selected from the group consisting of an alkylating agent, a reducing agent and a halogen-containing compound to a contained solvent, and circulating the mixture in a reaction system.

The present invention will be described in detail below. In the present invention, as the chromium-based catalyst, at least one compound (b) selected from the group consisting of chromium compound (a), amine, amide and imide, alkylaluminum compound (c) and halogen-containing compound (d). A catalyst system consisting of a combination of

The chromium compound used in the present invention is represented by the general formula CrXn. However, in the general formula, X represents an arbitrary organic group or inorganic group or a negative atom, n represents an integer of 1 to 6, and when n is 2 or more, X may be the same or different from each other. Good. The valence of chromium is 0 to 6, and n in the above formula is preferably 2 or more.

Examples of the organic group include various groups having usually 1 to 30 carbon atoms. Specific examples thereof include a hydrocarbon group, a carbonyl group, an alkoxy group, a carboxyl group, a β-diketonate group, a β-ketocarboxyl group, a β-ketoester group and an amide group. Examples of the hydrocarbon group include an alkyl group, a cycloalkyl group, an aryl group, an alkylaryl group, an aralkyl group, a cyclopentadienyl group and the like. Examples of the inorganic group include a chromium salt-forming group such as a nitrate group and a sulfate group, and examples of the negative atom include oxygen and halogen.

A preferred chromium compound is an alkoxy salt of chromium, a carboxyl salt, a β-diketonate salt, a salt of β-ketoester with an anion, or a chromium halide, and specifically, chromium (IV) tert-butoxide. , Chromium (III) acetylacetonate, chromium (III)
Trifluoroacetylacetonate, chromium (III) Hexafluoroacetylacetonate, chromium (III) (2
2,6,6-tetramethyl-3,5-heptanedionate), Cr (PhCOCHCOPh) ₃ (provided that P is
h represents a phenyl group. ), Chromium (II) acetate, chromium (III) acetate, chromium (III) 2-ethylhexanoate, chromium (III) benzoate, chromium (III) naphthenate, Cr (CH ₃ COCHCOOCH ₃ ) ₃ , chromium (III) chloride , Chromium chloride, chromium bromide, chromium bromide, chromium iodide, chromium iodide, chromium fluoride, chromium fluoride and the like.

Further, a complex composed of the above-mentioned chromium compound and an electron donor can also be preferably used. The electron donor is selected from compounds containing nitrogen, oxygen, phosphorus or sulfur.

Examples of the nitrogen-containing compound include nitriles, amines, amides, and the like. Specifically, acetonitrile, pyridine, dimethylpyridine, dimethylformamide, N-methylformamide, aniline, nitrobenzene, tetramethylethylenediamine, diethylamine,
Examples include isopropylamine, hexamethyldisilazane, and pyrrolidone.

Examples of oxygen-containing compounds include esters, ethers, ketones, alcohols, aldehydes,
Specific examples include ethyl acetate, methyl acetate, tetrahydrofuran, dioxane, diethyl ether, dimethoxyethane, diglyme, triglyme, acetone, methyl ethyl ketone, methanol, ethanol, acetaldehyde and the like.

Examples of phosphorus-containing compounds include hexamethylphosphamide, hexamethylphosphorus triamide, triethylphosphite, tributylphosphine oxide and triethylphosphine. On the other hand, examples of the sulfur-containing compound include carbon disulfide, dimethyl sulfoxide, tetramethylene sulfone, thiophene and dimethyl sulfide.

Therefore, as an example of a complex composed of a chromium compound and an electron donor, a chromium halide ether complex,
Ester complex, ketone complex, aldehyde complex, alcohol complex, amine complex, nitrile complex, phosphine complex,
Examples thereof include thioether complexes. Specifically, Cr
Cl ₃ / 3THF, CrCl ₃ / 3dioxane, C
_{rCl 3 · (CH 3 CO 2} n-C 4 H 9), CrCl 3
_{· (CH 3 CO 2 C 2} H 5), CrCl 3 · 3 (i-C
₃ H ₇ OH), CrCl ₃ · 3 [CH ₃ (CH ₂ ) ₃ C
H (C ₂ H ₅ ) CH ₂ OH], CrCl ₃ / 3pyri
_{dine, CrCl 3 · 2 (i} -C 3 H 7 NH 2),
[CrCl ₃ · 3CH ₃ CN] · CH ₃ CN, CrCl
_{3 · 3PPh 3, CrCl 2 ·} 2THF, CrCl 2 ·
2pyridine, CrCl ₂ · 2 [(C ₂ H ₅ ) ₂ N
H], CrCl ₂ · 2CH ₃ CN, CrCl ₂ · 2 [P
(CH ₃ ) ₂ Ph] and the like.

As the chromium compound, a compound soluble in a hydrocarbon solvent is preferable, and a β-diketonate salt of chromium,
Carboxylates, salts with anions of β-ketoesters, β
-Ketocarboxylic acid salts, amide complexes, carbonyl complexes, carbene complexes, various cyclopentadienyl complexes, alkyl complexes, phenyl complexes and the like. Examples of various carbonyl complexes of chromium, carbene complexes, cyclopentadienyl complexes, alkyl complexes, and phenyl complexes include Cr (CO) ₆ , (C ₆ H ₆ ) Cr (CO) ₃ ,
(CO) ₅ Cr (= CCH ₃ (OCH ₃ )), (CO)
₅ Cr (= CC ₆ H ₅ (OCH ₃ )), CpCrCl ₂
(Where Cp represents a cyclopentadienyl group), (
Cp * CrClCH ₃ ) ₂ (where Cp * represents a pentamethylcyclopentadienyl group), (CH ₃ ) ₂ CrC
1 and the like are exemplified.

The chromium compound can be used by supporting it on a carrier such as an inorganic oxide, but it is preferable to use it in combination with other catalyst components without supporting it on the carrier. That is, in the present invention, the chromium-based catalyst is used in a specific contact mode described later, but according to such a mode, high catalytic activity can be obtained without supporting the chromium compound on the carrier. When the chromium compound is used without being loaded on the carrier, the loading on the carrier which involves complicated operations can be omitted, and the total amount of the catalyst used (the total amount of the carrier and the catalyst component) is increased by the use of the carrier. It is possible to avoid the problem.

The amine used in the present invention is a primary or secondary amine.
It is a class amine. Examples of primary amines include ethylamine, isopropylamine, cyclohexylamine, benzylamine, aniline, naphthylamine, and the like.
As the secondary amine, diethylamine, diisopropylamine, dicyclohexylamine, dibenzylamine,
Bis (trimethylsilyl) amine, morpholine, imidazole, indoline, indole, pyrrole, 2,5-
Dimethylpyrrole, 3,4-dimethylpyrrole, 3,4
-Dichloropyrrole, 2,3,4,5-tetrachloropyrrole, 2-acylpyrrole, pyrazole, pyrrolidine and the like are exemplified.

Examples of the amide used in the present invention include metal amides derived from primary or secondary amines, such as the above primary or secondary amines and Group IA.
Mention may be made of amides obtained by reaction with metals selected from groups IIA, IIIB and IVB. Specific examples of such metal amides include lithium amide, sodium ethylamide, calcium diethylamide, lithium diisopropylamide, potassium benzylamide, sodium bis (trimethylsilyl) amide, lithium indolide, sodium pyrrolide, lithium pyrrolide and potassium. Examples thereof include pyrrolide, potassium pyrrolidide, aluminum diethylpyrrolide, ethylaluminum dipyrrolide and aluminum tripyrolide.

In the present invention, the above secondary amine,
Metal amides derived from secondary amines or mixtures thereof are preferably used. Particularly, as the secondary amine, pyrrole, 2,5-dimethylpyrrole, 3,4-dimethylpyrrole, 3,4-dichloropyrrole, 2,3,3.
4,5-tetrachloropyrrole, 2-acylpyrrole,
As the metal amide derived from the secondary amine, aluminum pyrrolide, ethylaluminum dipyrrolide, aluminum tripyrolide, sodium pyrrolide, lithium pyrrolide and potassium pyrrolide are preferable. Among the pyrrole derivatives, those having a hydrocarbon group on the pyrrole ring are particularly preferable.

Examples of the amide or imide compound other than the above used in the present invention include compounds represented by the following general formulas (1) to (3).

[0023]

Embedded image

In the general formula (1), M ¹ is a hydrogen atom or a metal element selected from groups IA, IIA and IIIB of the periodic table, and R ¹ is a hydrogen atom and an alkyl group having 1 to 30 carbon atoms. , An alkenyl group, an aralkyl group, an aryl group which may have a substituent, or an aryl group which may contain a hetero element, and R ² represents a hydrogen atom or a carbon number of 1 to 1.
30 alkyl group, alkenyl group, aralkyl group, aryl group optionally having substituent (s), aryl group optionally containing hetero element, or acyl group C (═O) R
³ (R ³ is the same definition as R ^1, R ¹ and may be different) represents, R ¹ and R ² may form a ring.

In the general formula (2), M ² and M ³ are hydrogen atoms or metal elements selected from the groups IA, IIA and IIIB of the periodic table, and R ⁴ and R ⁵ are hydrogen atoms and carbon numbers. 1
To 30 represents an alkyl group, an alkenyl group, an aralkyl group, an aryl group which may have a substituent, or an aryl group which may contain a hetero element, and R ⁴ and R ⁵ form a ring. Or, A represents an alkylene group which may contain an unsaturated bond.

In the general formula (3), M ⁴ is a hydrogen atom or a metal element selected from the groups IA, IIA and IIIB of the periodic table, and R ⁶ is a hydrogen atom or an alkyl group having 1 to 30 carbon atoms. , An alkenyl group, an aralkyl group, an aryl group which may have a substituent, or an aryl group which may contain a hetero element, and R ⁷ represents a hydrogen atom or a carbon number of 1 to 1.
30 alkyl group, alkenyl group, aralkyl group, aryl group which may have a substituent, aryl group which may contain a hetero element, or SO ₂ R ⁸ group (R ⁸ is the same definition as R ⁶ And may be different from R ⁶ ), and R ⁶ and R ⁷ may form a ring.

Examples of amides represented by the general formula (1) or (2) include acetamide, N-methylhexanamide, succinamide, maleamide, N-methylbenzamide, imidazole-2-carboxamide, Examples include di-2-thenoylamine, β-lactam, δ-lactam, ε-caprolactam, and salts thereof with a metal of Group IA, IIA or IIIB of the periodic table.
Examples of the imides include 1,2-cyclohexanedicarboximide, succinimide, phthalimide, maleimide, 2,4,6-piperidinetrione, perhydroazecin-2,10-dione, and those of the periodic table. Mention may be made of salts with metals of group IA, IIA or IIIB.

As the sulfonamides and sulfonimides represented by the general formula (3), for example, benzenesulfonamide, N-methylmethanesulfonamide, N-
Methyltrifluoromethylsulfonamide and salts of these with metals of Group IA, IIA or IIIB of the Periodic Table. Among these amide or imide compounds, the compound represented by the general formula (1) is preferable, and particularly,
An imide compound in which R ² in the general formula (1) represents an acyl group C (═O) R ³ and R ¹ and R ² form a ring is preferable.

In the present invention, an alkylaluminum compound represented by the following general formula (4) is preferably used as the alkylaluminum compound.

[0030]

Embedded image R ¹ _m Al (OR ² ) _n H _p X _q (4)

In the general formula (4), R ¹ and R ² are hydrocarbon groups having a carbon number of usually 1 to 15, preferably 1 to 8 and may be the same or different from each other. Represents a halogen atom, m is 0 <m ≦ 3, n is 0 ≦ n <3, p
Represents a number of 0 ≦ p <3, q represents a number of 0 ≦ q <3, and represents a number of m + n + p + q = 3.

Examples of the above alkylaluminum compound include trialkylaluminum compounds represented by the following general formula (5), halogenated alkylaluminum compounds represented by the general formula (6), and alkoxy groups represented by the general formula (7). Examples thereof include an aluminum compound and an alkylaluminum hydride compound represented by the general formula (8). The meanings of R ¹ , X and R ² in each formula are the same as above.

[0033]

Embedded image R ¹ ₃ Al (5) R ¹ _m AlX _3-m (m is 1.5 ≦ m <3) (6) R ¹ _m Al (OR ² ) _3-m ( m is 0 <m <3, preferably 1.5 ≦ m <3) (7) R ¹ _m AlH _3-m (8) (m is 0 <m <3, preferably 1. 5 ≦ m <3)

Specific examples of the alkylaluminum compound include trimethylaluminum, triethylaluminum, triisobutylaluminum, diethylaluminum monochloride, diethylaluminum ethoxide, diethylaluminum hydride and the like. Among these, trialkylaluminums are particularly preferable in that the amount of polymer by-products is small. The alkylaluminum compound may be a mixture of two or more kinds.

In the present invention, as the halogen-containing compound, there are IIIA, IIIB, IVA and IV of the periodic table.
A halogen-containing compound containing an element selected from the group consisting of B, VA and VB is preferably used. And, as the halogen, chlorine or bromine is preferable.

Specific examples of the above halogen-containing compound include scandium chloride, yttrium chloride, lanthanum chloride, titanium tetrachloride, zirconium tetrachloride, hafnium tetrachloride, boron trichloride, aluminum chloride, diethyl aluminum chloride, ethyl aluminum sesquichloride. , Gallium chloride, carbon tetrachloride, chloroform, methylene chloride, dichloroethane, trichloroethane, tetrachloroethane, hexachlorobenzene, 1,3,5-trichlorobenzene, hexachlorocyclohexane, trityl chloride, tetrachlorosilane, trimethylchlorosilane,
Germanium tetrachloride, tin tetrachloride, tributyltin chloride, phosphorus trichloride, antimony trichloride, trityl hexachloroantimonate, antimony pentachloride, bismuth trichloride, boron tribromide, aluminum tribromide, carbon tetrabromide, bromoform, bromo Examples thereof include benzene, iodomethane, silicon tetrabromide, hexafluorobenzene, aluminum fluoride and the like.

Among the above halogen-containing compounds, those having a large number of halogen atoms are preferable, and compounds soluble in the reaction solvent are preferable. Examples of particularly preferable halogen-containing compounds include carbon tetrachloride, chloroform, dichloroethane, tetrachloroethane, titanium tetrachloride, germanium tetrachloride, tin tetrachloride and the like. The halogen-containing compound may be used as a mixture of two or more kinds.

In the present invention, it is preferable to contact the α-olefin with the chromium-based catalyst in such a manner that the chromium compound (a) and the alkylaluminum compound (c) do not contact with each other in advance. According to such a specific contact mode, it is possible to selectively carry out the trimerization reaction and obtain 1-hexene from the raw material ethylene in a high yield.

The above-mentioned specific contact mode is specifically as follows.
(1) Method of introducing α-olefin and catalyst component (a) into a solution containing catalyst components (b) to (d), (2) Solution containing catalyst components (a), (b) and (d) A method of introducing α-olefin and the catalyst component (c) therein, (3) α-olefin in a solution containing the catalyst components (a) and (d),
A method of introducing the catalyst components (b) and (c), (4) α-olefin in a solution containing the catalyst components (c) and (d),
A method of introducing catalyst components (a) and (b), (5) a method of introducing α-olefin, catalyst components (c) and (d) into a solution containing catalyst components (a) and (b), (6)
A method of introducing α-olefin and catalyst components (a) and (d) into a solution containing catalyst components (b) and (c), (7)
A method of introducing α-olefin, catalyst components (a), (b) and (d) into a solution containing the catalyst component (c), (8)
A method of introducing α-olefin, catalyst components (b) to (d) into a solution containing the catalyst component (a), (9) α-olefin and each of the catalyst components (a) to (d) simultaneously and independently. Can be carried out by a method such as introduction into the reaction system. And each said solution is normally prepared using a reaction solvent.

In the present invention, "a mode in which the chromium compound and the alkylaluminum compound do not come into contact in advance"
Means not only at the start of the reaction, but also after the additional α-
It means that such a mode is maintained in the supply of the olefin and the catalyst component to the reactor. However, the particular embodiment described above is the preferred embodiment required in the preparation of the catalyst and is irrelevant after the catalyst has been prepared, thus the catalyst recovered from the reaction system is It can be recycled without contradiction.

The reason why the activity of the low polymerization reaction of α-olefin is low when the chromium-based catalyst is used in such a manner that the chromium compound and the alkylaluminum compound are in contact with each other in advance is not yet clear, but it is presumed as follows. To be done.

That is, it is considered that when the chromium compound and the alkylaluminum are brought into contact with each other, the ligand exchange reaction proceeds between the ligand coordinated with the chromium compound and the alkyl group in the alkylaluminum compound. And, the alkyl-chromium compound produced by such a reaction is unstable in itself, unlike the alkyl-chromium compound obtained by a usual method. Therefore, alkyl-
The decomposition / reduction reaction of the chromium compound preferentially proceeds, and as a result, inappropriate demetallation is induced in the low polymerization reaction of α-olefin, and the activity of the low polymerization reaction of α-olefin decreases.

In the present invention, a substituted or unsubstituted α-olefin having 2 to 30 carbon atoms is used as the raw material α-olefin. Specific examples include ethylene, propylene, 1-butene, 1-hexene, 1-octene, 3-methyl-1-butene, 4-methyl-1-pentene and the like. Particularly, ethylene is suitable as the raw material α-olefin, and 1-hexene, which is a trimer of ethylene, can be obtained from ethylene in high yield and high selectivity.

In the present invention, as a reaction solvent, butane, pentane, 3-methylpentane, hexane, heptane, 2-methylhexane, octane, cyclohexane,
C1-C20 chain or alicyclic saturated hydrocarbons such as methylcyclohexane, 2,2,4-trimethylpentane and decalin, aromatic hydrocarbons such as benzene, toluene, xylene, ethylbenzene, mesitylene and tetralin Is used. These may be used alone or as a mixed solvent.

As the reaction solvent, it is possible to use α-olefin as the reaction raw material itself or α-olefin other than the main raw material. As the reaction solvent, α-olefin having 4 to 30 carbon atoms is used, and α-olefin which is liquid at room temperature is particularly preferable.

Particularly, the reaction solvent has 4 to 1 carbon atoms.
Chain saturated hydrocarbons or alicyclic saturated hydrocarbons of 0 are preferred. By using these solvents, it is possible to suppress the by-product of the polymer, and further, when the alicyclic hydrocarbon is used, there is an advantage that a high catalytic activity can be obtained.

In the present invention, the amount of the chromium compound used is usually 1.0 × 10 ^{−7 to} 0.
5 mol, preferably 1.0 × 10 ^{−6 to} 0.2 mol,
More preferably, it is in the range of 1.0 × 10 ^{−5 to} 0.05 mol. On the other hand, the amount of the alkylaluminum compound used is usually 50 mmol or more per 1 mol of the chromium compound, but it is preferably 0.1 mol or more from the viewpoint of catalytic activity and selectivity of the trimer. And the upper limit is usually 1.0 × 10 ⁴ mol. Also, amine,
The amount of each amide or imide used is 1 mol of the chromium compound.
The amount is usually 0.001 mol or more, preferably 0.005 to 1000 mol, and more preferably 0.01.
It is set in the range of ˜100 mol. The amount of halogen-containing compound used is in the same range as the amount of amine, amide or imide used.

In the present invention, the chromium compound (a),
The molar ratio (a) :( b) of at least one compound (b) selected from the group of amines, amides and imides, the alkylaluminum compound (c) and the halogen-containing compound (d):
(C) :( d) is 1: 0.1-10: 1 to 100: 0.
1-20 are preferable and 1: 1-5: 5-50: 1-10
Is particularly preferable. By combining under such specific conditions, for example, hexene can be produced as an α-olefin low polymer in a yield of 90% or more (ratio to the total amount produced), and the purity of 1-hexene in hexene is high. To 99%
It can be increased above.

The reaction temperature is generally 0 to 250 ° C, preferably 0 to 150 ° C, more preferably 20 to 100 ° C. On the other hand, the reaction pressure is from normal pressure to 250 kg / cm ²
However, it is usually 100 kg / cm ²
Is sufficient. The residence time is usually in the range of 1 minute to 20 hours, preferably 0.5 to 6 hours. Coexistence of hydrogen during the reaction is preferable because improvement of catalytic activity and selectivity of trimer can be observed. In addition, the coexistence of hydrogen has an effect that the property of the by-produced polymer becomes powdery with less adhesion. The amount of hydrogen to coexist is usually 0.1 to 100 kg / c as hydrogen partial pressure.
m ² , preferably in the range of 1.0 to 80 kg / cm ² .

The greatest feature of the present invention is that the α-olefin low polymer is first separated by distillation from the reaction solution, and then the recovered catalyst component-containing solvent is added with an alkylating agent, a reducing agent and a halogen-containing compound. The point is to add at least one selected component and circulate it in the reaction system. Then, in a preferred embodiment of the present invention, the by-produced polymer in the reaction solution is separated prior to the distillative separation of the α-olefin low polymer.

Separation and removal of the by-produced polymer in the reaction solution can be carried out without melting the by-produced polymer by appropriately using a known solid-liquid separator. A filter or a centrifuge is preferably used as the solid-liquid separator. The α-olefin low polymer can be separated by distillation according to a known method. The α-olefin low polymer does not necessarily have to be separated by distillation for all the components in the reaction solution. For example, when 1-hexene is produced from ethylene, a small amount of another α-olefin low polymer such as 1-octene can be left in the reaction solution without being separated.
Also, by-products such as C _10-20 components can be left in the reaction solution.

Examples of the alkylating agent added to the catalyst component-containing solvent include the alkylaluminum compounds such as triethylaluminum described above as one of the catalyst components. Other alkylating agents include Grignard reagent (RMgX), alkyl lithium (RL
i), alkylborane (BR ₃ ) and the like. Such an alkylaluminum compound also acts as a reducing agent at the same time. Therefore, an alkylaluminum compound as an alkylating agent is used as the reducing agent added to the catalyst component-containing solvent, but the reducing agent is not limited thereto, and an ordinary reducing agent can also be used. Usual reducing agents include, for example, NaBH ₄ , LiAlH ₄ , LiH, NaH, K
Suitable examples include H, Na, K, Mg, and H ₂ . Also,
Examples of the halogen-containing compound include the halogen-containing compounds described above as one of the catalyst components.

The addition amount of each of the above-mentioned components per time is not particularly limited, but the alkylating agent and the reducing agent are usually regarded as the reducing agent and the chromium compound ( a) 1 to 100 mol is preferable, and 5 to 50 mol is particularly preferable, per 1 mol. Further, in the case of a halogen-containing compound, the addition amount per time is preferably 0.1 to 20 mol, and particularly preferably 1 to 10 mol, per 1 mol of the chromium compound (a) used for catalyst preparation, as in the above. preferable.

The catalyst activated by adding at least one of the above-mentioned components is circulated in the reaction system as a solvent containing a catalyst component for circulation. In the present invention, in particular, highly pure 1-hexene can be industrially advantageously produced from ethylene. Then, by a polymerization reaction using a known polymerization catalyst, L-LDPE, which is a useful resin, can be produced from 1-hexene obtained by the production method of the present invention.

[0055]

EXAMPLES The present invention will be described in more detail with reference to Examples and Comparative Examples, but the present invention is not limited to the following Examples unless it exceeds the gist.

Example 1 A 2 L autoclave that had been heated and dried in a drier at 120 ° C. was assembled while hot, and then vacuum nitrogen substitution was performed. The autoclave was equipped with a catalyst component feed tube equipped with a rupture plate. n-heptane (730 ml), 2,5-
A solution of dimethylpyrrole (0.140 mmol) in n-heptane, triethylaluminum (0.700 mmo
l) in n-heptane, 1,1,2,2-tetrachloroethane (39.4 mg, 0.235 mmol) in n-
Charge the heptane solution to the barrel side of the autoclave, while
A catalyst component feed tube was charged with a solution of chromium (III) 2-ethylhexanoate (22.5 mg, 0.047 mmol) in n-heptane. The total amount of n-heptane is 750.
It was ml.

First, the autoclave is heated to 80 ° C.,
Then, ethylene was introduced through the catalyst component feed pipe.
The rupture plate ruptured due to ethylene pressure, and the chromium compound was introduced into the barrel side of the autoclave to start low polymerization of ethylene. Ethylene was introduced until the total pressure reached 35 Kg / cm ² G, then the total pressure was increased to 35 Kg / cm ² G and the temperature was adjusted to 8
Maintained at 0 ° C. After 0.5 hours, the pressure of the autoclave was released to perform degassing, and the by-produced polymer (mainly polyethylene) in the reaction solution was separated and removed by a filter to recover the reaction solution. The results of the composition analysis of the α-olefin low polymer in the reaction solution by gas chromatography are shown in Table 1 (Example 1A).

Then, the reaction solution is distilled to separate the C ₄ and C ₆ components, and the remaining reaction solution (catalyst component, C ₈ component, C
Triethylaluminum (0.24 mmol) was added to an n-heptane solution containing _10-20 components to prepare a solvent containing a catalyst component for circulation. Then, argon gas was introduced into the autoclave to replace ethylene gas, and the solvent containing the circulating catalyst component was charged, and the total pressure was 3%.
Ethylene was introduced until it reached 5 Kg / cm ² G, then
The second reaction was carried out while maintaining the total pressure at 35 Kg / cm ² G and the temperature at 80 ° C. After 1.0 hour, the pressure of the autoclave was released to perform degassing, and then the by-product polymer (mainly polyethylene) in the reaction solution was separated and removed by a filter to collect the reaction solution. The results of the composition analysis of the α-olefin low polymer in the reaction solution by gas chromatography are shown in Table 1 (Example 1B).

Example 2 In Example 1, 1,1,2,2-tetrachloroethane (0.235) was used when preparing a solvent containing a circulating catalyst component.
The first reaction and the second reaction were performed in the same manner as in Example 1 except that (mmol) was used. Table 1 shows the results of composition analysis by gas chromatography of the α-olefin low polymer in each reaction solution. Example 2A is the result of the first reaction and Example 2B is the result of the second reaction.

Example 3 In Example 1, triethylaluminum (0.701 mmol) and 1,1,2,2-tetrachloroethane (0.240 mm) were used in preparing the solvent containing the circulating catalyst component.
The reaction of the 1st time and the reaction of the 2nd time were performed like Example 1 except having used ol). Table 2 shows the results of the composition analysis of the α-olefin low polymer in each reaction solution by gas chromatography. Example 3A is the result of the first reaction, and Example 3B is the result of the second reaction.

Comparative Example 1 In Example 1, the first reaction and the second reaction were carried out in the same manner as in Example 1 except that triethylaluminum was not used when preparing the solvent containing the circulating catalyst component. Table 2 shows the results of the composition analysis of the α-olefin low polymer in each reaction solution by gas chromatography. Comparative Example 1
A is the result of the first reaction, and Comparative Example 1B is the result of the second reaction.

In each table, the solvent type "HP" is n-heptane, the Cr compound type Cr (2EHA) ₃ is chromium (III) 2-ethylhexanoate, and the halide type TCE is 1.
It represents 1,2,2-tetrachloroethane, the unit of catalytic efficiency is g-α-olephine / 1g-chromium, and the unit of catalytic activity is g-α-olefin / 1g-chromium · Hr.

[0063]

[Table 1] ──────────────────────────────────── Example 1A 1B 2A 2B Solvent type (amount : ml) HP (750) HP (750) HP (750) HP (750) Cr Compound type Cr (2EHA) ₃ Cr (2EHA) ₃ Cr (2EHA) ₃ Cr (2EHA) ₃ Cr Compound amount (mg) 22.5 22.5 22.5 22.5 Cr Compound (mmol) (a) 0.047 0.047 0.047 0.047 2,5-Dimethylprolol (mmol) (b) 0.140 0.140 0.140 0.140 Et ₃ Al (mmol) (c) 0.701 0.941 0.701 0.701 Halide type TCE TCE TCE TCE Halide (mmol) (d) 0.240 0.240 0.240 0.480 Catalyst component molar ratio (a: b: c: d) 1: 3: 15: 5 1: 3: 20: 5 1: 3: 15: 5 1: 3: 15:10 Reaction temperature (℃) 80 80 80 80 Ethylene pressure (Kg / cm ² G) 35 35 35 35 Reaction time (Hr) 0.5 1.0 0.5 1.0 <Product amount (g)> 223.7 495.6 225.1 450.1 <Composition distribution (wt) %)> C ₄ 0.3 0.1 0.3 0.1 C ₆ Overall 91.9 92.2 91.6 93.0 1-hexene content in C ₆ (wt%) 98.1 98.8 98.5 98.9 C ₈ 0.6 0.5 0.6 0.5 C _10-20 7.1 7.2 7.4 6.3 By-product P E 0.17 0.08 0.12 0.10 <Catalyst efficiency> 95598 211795 96197 192350 <Catalytic activity> 191196 211795 192394 192350 ────────────────────────────── ───────

[0064]

[Table 2] ──────────────────────────────────── Examples Comparative Examples 3A 3B 1A 1B Solvent type (Amount: ml) HP (750) HP (750) HP (750) HP (750) Cr Compound type Cr (2EHA) ₃ Cr (2EHA) ₃ Cr (2EHA) ₃ Cr (2EHA) ₃ Cr Compound amount (mg) 22.5 22.5 22.5 22.5 Cr Compound (mmol) (a) 0.047 0.047 0.047 0.047 2,5-Dimethylprolol (mmol) (b) 0.140 0.140 0.140 0.140 Et ₃ Al (mmol) (c) 0.701 1.402 0.701 0.701 Halogenate type TCE TCE TCE TCE Halide (mmol) (d) 0.240 0.480 0.240 0.240 Catalyst component molar ratio (a: b: c: d) 1: 3: 15: 5 1: 3: 30: 10 1: 3: 15: 5 1: 3: 15: 5 Reaction temperature (℃) 80 80 80 80 Ethylene pressure (Kg / cm ² G) 35 35 35 35 Reaction time (Hr) 0.5 1.0 0.5 1.0 <Product amount (g)> 220.5 502.3 215.8 311.3 <Composition distribution (wt%)> C ₄ 0.3 0.1 0.3 0.1 C ₆ Overall 91.5 92.5 91.0 91.8 1-hexene content in C ₆ (wt%) 98.2 98.9 97.9 98.4 C ₈ 0.6 0.6 0.6 0.6 C _10-20 7.5 6.7 7.9 7.3 By-product PE 0.10 0.09 0.12 0.08 <Catalytic efficiency> 94231 214658 92222 133034 <Catalytic activity> 188462 214658 184444 133034 ──────────────────────────── ─────────

[0065]

According to the present invention described above, a method for producing an α-olefin low polymer using a chromium-based catalyst, which comprises activating the catalyst by a simple operation to circulate it in the reaction system, In particular, there is provided an industrially advantageous method for producing an α-olefin low polymer, which is capable of producing an α-olefin low polymer mainly composed of 1-hexene from ethylene with a high yield and a high selectivity.

─────────────────────────────────────────────────── ─── Continuation of the front page (51) Int.Cl. ⁶ Identification number Reference number within the agency FI Technical display location // C07B 61/00 300 C07B 61/00 300 (72) Inventor Miaki Namba Ushio Kurashiki, Okayama 3-10-10 Tsudori, Mizushima Development Laboratory, Mitsubishi Chemical Co., Ltd. (72) Inventor Takeshi Okano 3-10-10, Shiodotsu, Kurashiki, Okayama Mitsubishi Chemical Corporation, Mizushima Development Laboratory

Claims (4)

[Claims] 1. A method for producing an α-olefin low polymer using a chromium catalyst, wherein the chromium catalyst is at least one compound selected from the group consisting of a chromium compound (a), an amine, an amide and an imide. Using a catalyst system consisting of a combination of (b), an alkylaluminum compound (c) and a halogen-containing compound (d), a low polymerization of α-olefin was carried out in a solvent, and α
-Olefin low polymer is separated by distillation, and then at least one component selected from the group consisting of an alkylating agent, a reducing agent and a halogen-containing compound is added to the recovered catalyst component-containing solvent and then recycled to the reaction system. A method for producing an α-olefin low polymer, which comprises: 2. The α- according to claim 1, wherein the halogen-containing compound (d) is a halogen-containing compound containing an element selected from the group IIIA, IIIB, IVA, IVB, VA and VB of the periodic table. Method for producing olefin low polymer. 3. A molar ratio of catalyst components (a) :( b):
(C): (d) is 1: 0.1-10: 1 to 100: 0.
It is 1-20, The manufacturing method of the alpha-olefin low polymer of Claim 1 or 2. 4. The α-olefin low according to any one of claims 1 to 3, wherein the α-olefin and the chromium-based catalyst are brought into contact with each other in such a manner that the chromium compound (a) and the alkylaluminum compound (c) do not come into contact with each other in advance. Method for producing polymer.