JP3473192B2 - Method for producing α-olefin low polymer - Google Patents

Description

Detailed Description of the Invention

[0001]

TECHNICAL FIELD The present invention relates to a method for producing an α-olefin low polymer. More specifically, it relates to a method for producing an α-olefin low polymer industrially advantageously with high yield and high selectivity by using a catalyst whose deterioration over time is improved.

[0002]

2. Description of the Related Art Heretofore, as a low polymerization method for α-olefins such as ethylene, there has been known a method using a chromium-based catalyst comprising a combination of a specific chromium compound and a specific organoaluminum compound. For example, Japanese Patent Laid-Open No. 3-12
Japanese Patent No. 8904 describes a method of trimerizing an α-olefin using a catalyst obtained by previously reacting a chromium-containing compound having a chromium-pyrrolyl bond with a metal alkyl or a Lewis acid.

Also, South African Patent ZA93 / 0350
Describes a method for low polymerization of α-olefins using a catalyst system obtained by mixing a chromium compound, a pyrrole-containing compound, a metal alkyl compound and a halide source in a common solvent. Some of the inventors of the present invention have previously disclosed, in Japanese Patent Application No. 6-139024, a chromium compound,
Amine or metal amide, alkyl aluminum compound,
And a method of carrying out a low polymerization reaction of an α-olefin by contacting a halogen-containing compound with the α-olefin in a specific manner.

[0004]

However, in the method described in South African Patent ZA93 / 0350, the catalytic activity at the early stage of the reaction is high, but the deterioration with time is severe, and the reaction time cannot be long, so a large amount of the catalyst is used. However, the catalyst cost is high, and the catalyst preparation process and the catalyst isolation process are required, the operation is complicated, and the construction cost required for the entire manufacturing process is high.

Further, according to the method described in Japanese Patent Application No. 6-139024, especially by the low polymerization reaction of ethylene, 1
-Hexene can be obtained with high selectivity and high activity, but for industrial use, further improvement is desired in terms of deterioration of the catalyst over time. The present invention has been made in view of the above circumstances, and an object thereof is to use a catalyst whose deterioration with time is significantly improved and to industrially advantageously produce an α-olefin low polymer such as 1-hexene without complicated operations. An object of the present invention is to provide a method for producing an α-olefin low polymer capable of producing a high yield and a high selectivity.

[0006]

Means for Solving the Problems As a result of intensive studies conducted by the present inventors in order to achieve the above object, the present inventors use a specific chromium-based catalyst containing a specific halogenated hydrocarbon in a specific contact mode. Then, if a low polymerization reaction of α-olefin, especially a low polymerization reaction mainly composed of trimerization of ethylene proceeds highly active, and a high-purity α-olefin low polymer, particularly 1-hexene is produced. I got the knowledge of.

The present invention has been completed based on the above findings, and the gist thereof is a method for producing an α-olefin low polymer using a chromium-based catalyst, wherein at least the chromium compound is used as the chromium-based catalyst. A catalyst system comprising a combination of (a), at least one nitrogen-containing compound (b) selected from the group consisting of amines, amides and imides, an alkylaluminum compound (c) and a halogen-containing compound (d) in catalytic amounts. Before the low polymerization reaction is started by using the above components (a) to (d) and the α-olefin in the reaction solvent at the same time, the chromium compound (a) and the alkylaluminum compound (c) are used. ) Is not contacted with the above components (a) to (d) to the reaction system to obtain α
A method for producing an α-olefin low polymer by contacting with an olefin, wherein the halogen-containing compound (d) is 3
A process for producing an α-olefin low polymer, which is a straight-chain hydrocarbon having 2 or more carbon atoms substituted with one or more halogen atoms.

[0008]

BEST MODE FOR CARRYING OUT THE INVENTION The present invention will be described in more detail below. In the present invention, as the chromium-based catalyst, at least the chromium compound (a) and the specific nitrogen-containing compound (b) are used.
And a catalyst system comprising a combination of an alkylaluminum compound (c) and a linear hydrocarbon having 2 or more carbon atoms (d) substituted with 3 or more halogen atoms.

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

The above organic group usually has 1 to 3 carbon atoms.
Various groups of 0 are mentioned. Specifically, a hydrocarbon group,
Examples thereof include 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 and a cyclopentadienyl group. 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,
A carboxyl salt, a β-diketonate salt, a salt with an anion of a β-ketoester, or a chromium halide, and specifically, chromium (IV) -t-butoxide, chromium (III) acetylacetonate, chromium (III) Trifluoroacetylacetonate, chromium (III) Hexafluoroacetylacetonate, chromium (III) (2,2,6
6-tetramethyl-3,5-heptanedionate), C
r (PhCOCHCOPh) ₃ (where Ph 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, a first chromium chloride, chromic chloride, bromide first chromium , Chromium bromide, chromium iodide, chromium iodide, chromium fluoride, chromium fluoride and the like.

Further, a complex composed of the above chromium compound and an electron donor can also be preferably used. The electron donor is selected, for example, from compounds containing nitrogen, oxygen, phosphorus or sulfur. Examples of the nitrogen-containing compound include nitrile, amine, and amide. Specifically, acetonitrile, pyridine, dimethylpyridine, dimethylformamide, N-methylformamide, aniline, nitrobenzene, tetramethylethylenediamine,
Examples thereof include diethylamine, isopropylamine, hexamethyldisilazane, pyrrolidone and the like.

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

Therefore, from the chromium compound and the electron donor,
An example of the complex is a chromium halide ether complex.
Body, ester complex, ketone complex, aldehyde complex, al
Cole complex, amine complex, nitrile complex, phosphine complex
Body, thioether complex and the like. Specifically, C
rCl₃・ 3THF (where THF is tetrahydrofuran
), CrCl₃・ 3DOX (where DOX is
Oxane), CrCl₃・ (CH₃CO₂C_FourH
₉-N), CrCl₃・ (CH₃CO₂C₂H_Five), C
rCl₃・ 3 (i-C₃H₇OH), CrCl₃・ 3
[CH₃(CH₂) ₃CH (C₂H_Five) CH₂OH],
CrCl₃3Pyd (where Pyd represents pyridine)
), CrCl₃・ 2 (i-C₃H₇NH₂), [Cr
Cl₃・ 3CH ₃CN] ・ CH₃CN, CrCl₃・ 3
PPh₃, CrCl₂・ 2THF, CrCl₂・ 2Py
d, CrCl₂・ 2 [(C₂H_Five)₂NH], CrCl
₂・ 2CH₃CN, CrCl₂・ 2 [P (CH₃)₂P
h] and the like.

The chromium compound is compatible with hydrocarbon solvents.
Soluble compounds are preferred, chromium β-diketonate salts,
Carboxylates, salts with anions of β-ketoesters, β
-Ketocarboxylates, amide complexes, carbonyl complexes,
Ruben complex, various cyclopentadienyl complexes, alkyl
Examples thereof include complexes and phenyl complexes. Various cals of chrome
Bonyl complex, carbene complex, cyclopentadienyl complex
As a compound, an alkyl complex, a phenyl complex, etc., Cr (C
O)₆, (C₆H₆) Cr (CO)₃, (CO) _FiveCr
(= CCH₃(OCH₃)), (CO)_FiveCr (= CC
₆H_Five(OCH₃)), CpCrCl₂(Where Cp is
Indicates a cyclopentadienyl group. ), (Cp * CrCl
CH₃)₂(Where Cp * is pentamethylcyclopenta
Indicates a dienyl group. ), (CH₃)₂Examples include CrCl
To be done.

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, a 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.

Nitrogen-containing compound (b) used in the present invention
Is one or more compounds selected from the group consisting of amines, amides and imides. The amine used in the present invention is
It is a primary or secondary amine, or a mixture thereof. Examples of primary amines include ammonia, ethylamine, isopropylamine, cyclohexylamine, benzylamine, aniline, and naphthylamine, and secondary amines include diethylamine, diisopropylamine, dicyclohexylamine, dibenzylamine, bis (trimethylsilyl) amine, Morpholine, imidazole, indoline, indole, pyrrole, 2,5-dimethylpyrrole, 3,4-dimethylpyrrole, 3,4-diethylpyrrole, 2,3,4-trimethylpyrrole,
3,4-dichloropyrrole, 2,3,4,5-tetrachloropyrrole, 2-acetylpyrrole, 3,3 ', 4
Examples include 4'-tetramethyldipyrrolomethane, pyrazole, pyrrolidine and the like.

One of the amides used in the present invention is a metal amide derived from a primary or secondary amine, or a mixture thereof, and specifically, a primary or secondary amine and a group IA. An amide obtained by reaction with a metal selected from Group IIA, Group IIIA, and Group 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 pyrrolide. , Potassium pyrrolidide, aluminum diethylpyrrolid, ethylaluminum dipyrrolide, aluminum tripyrrolid, lithium (2,5-dimethylpyrrolid) and the like.

In the present invention, a secondary amine, an amide derived from a secondary amine, or a mixture thereof is more preferably used. As secondary amines, pyrrole, 2,5-dimethylpyrrole, 3,4-dimethylpyrrole, 2,3,4-trimethylpyrrole, 3,4-dichloropyrrole, 2,3,4,5-tetrachloropyrrole, 2-Acetylpyrrole and 3,3'-4,4'-tetramethyldipyrrolomethane are preferable, and pyrrole or 2,5-dimethylpyrrole is particularly preferable. In addition, examples of the metal amide derived from a secondary amine include aluminum pyrrolide, ethylaluminum dipyrrolide, aluminum tripyrolide, sodium pyrrolide, lithium pyrrolide, potassium pyrrolide, and aluminum (2,5-dimethylpyrrolidone. ), Ethylaluminum bis (2,5-dimethylpyrrolide), aluminum tris (2,5-dimethylpyrrolide), sodium (2,5-dimethylpyrrolide), lithium (2,5-dimethylpyrrolide), Potassium (2,5-dimethylpyrrolid) is preferred. Among the pyrrole derivatives, those having a hydrocarbon group on the pyrrole ring are preferable.

Another one of the amides used in the present invention is an acid amide. Examples of the acid amide used in the present invention include compounds represented by the following general formulas (1) to (3). In addition, for convenience, the following general formulas (1) to (3) also include imide which is another nitrogen-containing compound used in the present invention. Examples of the acid amide or imide compound used in the present invention include compounds represented by the following general formulas (1) to (3).

[0022]

[Chemical 4]

In the general formula (1), M ¹ is a hydrogen atom or a metal element selected from the groups IA, IIA, IB or IIIA of the periodic table, and R ¹ is a hydrogen atom or a carbon number of 1 to 3
0 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 ² represents a hydrogen atom or a carbon number of 1 to 30. , An alkyl group, an alkenyl group, an aralkyl group, an aryl group which may have a substituent, an aryl group which may contain a hetero element, or an acyl group C (═O) R ³ (where R ³ is defined as Same as R ¹ , but
R ¹ may be different) and R ¹ and R ² may form a ring.

[0024]

[Chemical 5]

In the general formula (2), M ² and M ³ are hydrogen atoms or metal elements selected from the group IA, IIA, IB or IIIA of the periodic table, R ⁴ and R ⁵ are hydrogen atoms, Represents 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,
R ⁴ and R ⁵ may form a ring, and A represents an alkylene group which may contain an unsaturated bond.

Examples of the acid amides represented by the general formula (1) or the general formula (2) include acetamide, N-methylhexanamide, succinamide, maleamide and N-.
Methylbenzamide, imidazole-2-carboxamide, di-2-thenoylamine, β-lactam, δ-lactam, ε-caprolactam, and salts thereof with metals of Group IA, IIA, IB or IIIA of the Periodic Table. To be

Examples of the imides include 1,2-cyclohexanedicarboximide, succinimide, phthalimide, maleimide, 2,4,6-piperidinetrione, perhydroazecin-2,10-dione, and
Salts thereof with salts of Group IA, IIA, IB or IIIA of the Periodic Table can be mentioned.

[0028]

[Chemical 6]

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

Examples of the sulfonamides and sulfonimides represented by the general formula (3) include benzenesulfonamide, N-methylmethanesulfonamide, N-
Methyltrifluoromethanesulfonamide and salts thereof with metals of Group IA, IIA, IB or IIIA of the Periodic Table.

Among the above acid amide or imide compounds, the compounds represented by the general formula (1) are 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 ³ form a ring is preferable. As the alkylaluminum compound (c) used in the present invention, an alkylaluminum compound represented by the following general formula (4) is preferably used.

[0032]

[Chemical 7]

In the formula (4), R ¹ and R ² are hydrocarbon groups having 1 to 15 carbon atoms, preferably 1 to 8 carbon atoms,
They may be the same or different, and X represents a halogen atom. m, n, p and q each represent a number, and m is 0
<M ≦ 3, n is 0 ≦ n <3, p is 0 ≦ p <3, and q is 0 ≦
q <3 and m + n + p + q = 3. Examples of the alkylaluminum compound include a trialkylaluminum compound represented by the following general formula (5), a halogenated alkylaluminum compound represented by the general formula (6), an alkoxyalkylaluminum compound represented by the general formula (7), Examples thereof include an alkylaluminum hydride compound represented by the general formula (8). The definitions of R ¹ , X and R ² in each formula are the same as in formula (4).

[0034]

[Chemical 8]

Specific examples of the above alkylaluminum compound include trimethylaluminum, triethylaluminum, triisobutylaluminum, diethylaluminum monochloride, diethylaluminum ethoxide, diethylaluminum hydride and the like. Further, these alkylaluminum compounds may be a mixture of two or more kinds, and for example, a mixture of a trialkylaluminum compound and a halogenated alkylaluminum compound can be used. Among these, trialkylaluminum compounds are particularly preferable in that the amount of by-products of the polymer is small.

The halogen-containing compound (d) used in the present invention is a straight-chain hydrocarbon having 2 or more carbon atoms, preferably a straight-chain saturated hydrocarbon, substituted with 3 or more halogen atoms. Is used. Among them, linear saturated hydrocarbons in which two or more adjacent carbon atoms are substituted with three or more halogen atoms are preferable, and particularly, the general formulas (I) and (II),
Straight-chain halogenated hydrocarbons represented by (III) are preferred.

[0037]

[Chemical 9]

(In the general formula (I), X _{1 to} X ₈ each independently represent a hydrogen atom or a halogen atom, and X _{1 to} X ₅
Of these, at least 3 are halogen atoms and 1 is 0-8. )

[0039]

[Chemical 10] (In the general formula (II), Hal _{1 to} Hal ₃ represent a halogen atom, X _{9 to} X ₁₃ are each independently a halogen atom or a hydrogen atom, and m is 0 to 8.)

[0040]

[Chemical 11]

(In the general formula (III), Hal _{4 to} Hal ₇ represent a halogen atom, X _{14 to} X ₁₇ are each independently a halogen atom or a hydrogen atom, and n is 0 to 8.) As the halogen atom of the substituent in the halogen-containing compound (d), it is preferable to use chlorine or bromine, and particularly chlorine in view of the activity and the selectivity of the target product. L, m and n in the general formulas (I) to (III) are
0 to 3 is preferable for each. As the halogen-containing compound (d), specifically, 1,1,1-trichloroethane, 1,
1,2-trichloroethane, 1,1,2,2-tetrachloroethane, pentachloroethane, hexachloroethane, 1,1,1-trichloropropane, 1,1,2,2
-Tetrachloropropane, 1,1,1-trichlorobutane, 1,1,2,2-tetrachlorobutane, 1,1,1
-Trichloropentane, 1,1,2,2-tetrachloropentane, 1,1,1-tribromoethane, 1,1,
2,2-tetrabromoethane and the like, and particularly 1,
1,1-trichloroethane, pentachloroethane, hexachloroethane and 1,1,2,2-tetrachloroethane are preferred.

In the present invention, the use of the above-mentioned halogen-containing compound (d) has an advantage that not only the catalytic activity and the selectivity of the trimer can be remarkably improved but also the deterioration of the catalytic activity with time can be improved. In the present invention, a chromium-based catalyst comprising a combination of the above catalyst components (a) to (d) in the respective catalytic amounts is used in a reaction solvent with α
-Perform a low polymerization reaction of olefins. Then, in the reaction solvent, before the low polymerization reaction is initiated by the simultaneous presence of the above components (a) to (d) and the α-olefin, the chromium compound (a) and the alkylaluminum compound (c) are added. In a mode where they do not contact with each other, α-
It is contacted with an olefin to cause a low polymerization reaction of α-olefin. By adopting this contact mode, there are advantages that the catalytic activity is remarkably improved, the trimer selectivity is very high, and the content of the obtained α-olefin low polymer is extremely high.

The reason why the activity of the low polymerization reaction of α-olefin becomes low when the chromium-based catalyst is used in such a manner that the chromium compound (a) and the alkylaluminum compound (c) are in contact with each other in advance is not clear. , Is estimated as follows. That is, it is considered that when the chromium compound and the alkylaluminum compound are brought into contact with each other, the ligand exchange reaction proceeds between the ligand coordinated to the chromium salt and the alkyl group in the alkylaluminum compound. The alkyl-chromium compound produced by such a reaction is unstable in itself, unlike the alkyl-chromium compound obtained by the usual method. Therefore, the decomposition-reduction reaction of the alkyl-chromium compound preferentially proceeds, and as a result, inappropriate demetallation is induced in the low polymerization reaction of the α-olefin, and the low polymerization reaction activity of the α-olefin is considered to decrease. To be

In this particular contact mode, it is preferable to use a high concentration of α-olefin in order to improve the catalytic activity and the selectivity of the target product. In particular,
The α-olefin concentration in the reaction solvent is usually 5 to 100 m.
It is preferable to bring the chromium-based catalyst and the α-olefin into contact with each other under the conditions of ol%, preferably 10 to 100 mol%, and particularly preferably 20 to 100 mol%. In particular,
When a low-boiling α-olefin such as ethylene is used as the α-olefin, the α-olefin pressure is usually about 3 to.
250 kg / cm ² , preferably about 5-100 kg / c
It is preferable that the contact is carried out under the condition of m ² , more preferably about 5 to 50 kg / cm ² . By contacting under such conditions, the α
-Low polymerization of olefins can be carried out.

Specific examples of the above specific contact modes include the following modes (1) to (9). In addition,
The following solutions are usually prepared using a reaction solvent. (1) A method of introducing a chromium compound (a) and an α-olefin into a solution containing a nitrogen-containing compound (b), an alkylaluminum compound (c) and a halogen-containing compound (d).

(2) A method of introducing an alkylaluminum compound (c) and an α-olefin into a solution containing a chromium compound (a), a halogen-containing compound (d) and a nitrogen-containing compound (b). (3) A method of introducing a nitrogen-containing compound (b), an alkylaluminum compound (c) and an α-olefin into a solution containing a chromium compound (a) and a halogen-containing compound (d).

(4) Alkyl aluminum compound (c)
And a method of introducing the chromium compound (a), the nitrogen-containing compound (b) and the α-olefin into a solution containing the halogen-containing compound (d). (5) A method of introducing an alkylaluminum compound (c), a halogen-containing compound (d) and an α-olefin into a solution containing a chromium compound (a) and a nitrogen-containing compound (b).

(6) A method of introducing a chromium compound (a), a halogen-containing compound (d) and an α-olefin into a solution containing a nitrogen-containing compound (b) and an alkylaluminum compound (c). (7) A method of introducing a chromium compound (a), a nitrogen-containing compound (b), a halogen-containing compound (d) and an α-olefin into a solution containing the alkylaluminum compound (c).

(8) A method of introducing a halogen-containing compound (d), a nitrogen-containing compound (b), an alkylaluminum compound (c) and an α-olefin into a solution containing the chromium compound (a). (9) A method of independently supplying the chromium compound (a) and the alkylaluminum compound (c) to the reaction system simultaneously with the α-olefin during the low polymerization reaction of the α-olefin. In this case, the chromium compound (a), the nitrogen-containing compound (b),
It is also possible to adopt a method in which the alkylaluminum compound (c), the halogen-containing compound (d) and the α-olefin are simultaneously and independently introduced into the reaction system.

In the present invention, the phrase "a mode in which the chromium compound and the alkylaluminum compound are not brought into contact with each other before the start of the reaction" refers not only to the start of the reaction but also to the reactor for additional α-olefin and the catalyst component thereafter. It means that this aspect is maintained even in the supply of. However, the particular contact mode described above is the preferred mode required in the formation of the catalyst system from the catalyst components and is irrelevant after the catalyst system is formed. Therefore, circulating the catalyst liquid recovered from the reaction system through the reaction system after the formation of the catalyst system according to the above mode is not contrary to the above contact mode.

In the present invention, the amount of the chromium compound (a) present in the reaction system is usually 1 × 1 per liter of solvent.
0 ^{−7 to} 0.5 mol, preferably 5 × 10 ^{−7 to} 0.2 m
and more preferably 1 × 10 ^{−6 to} 5 × 10 ⁻² mol. The amount of the nitrogen-containing compound (b) present is usually 1 × 10 ^{−7 to} 0.1 mol, preferably 5 × 10 ^{−7 to} 5 × 10 ⁻² mol, and more preferably 1 × 10 ⁻⁶ per 1 liter of the solvent. ˜1 × 10 ⁻² mol. The amount of the alkylaluminum compound (c) present is 1 × 10 ^{−7 to} 7 × 10 ⁻² mol, preferably 5 × 10 ^{−7 to} 5 × 10 ⁻² mol, and more preferably 1 ×, per 1 liter of the solvent.
It is set in the range of 10 ⁻⁶ to 1 × 10 ⁻² mol. The amount of the halogen-containing compound (d) present is usually 1 × 10 ^{−7 to} 0.1 mol, preferably 5 × 10 ⁻⁷ to 1 mol of the solvent.
5 × 10 ⁻² mol, more preferably 1 × 10 ⁻⁶ to 1 × 1
The range is 0 ^-2 mol.

In the present invention, the molar ratio (a) :( b) :( c) of the chromium compound (a), the nitrogen-containing compound (b), the alkylaluminum compound (c) and the halogen-containing compound (d) in the reaction system. ): (D) is usually 1: 0.1
~ 100: 0.1-500: 0.1-100,
The ratio is more preferably 1: 0.1 to 10: 1 to 100: 0.1 to 20, and particularly preferably 1: 1 to 5: 5 to 50: 1 to 10. By combining under such specific conditions, as the α-olefin low polymer, for example, hexene can be produced in a yield of 90% or more (ratio to the total amount produced), and
The content of 1-hexene in hexene can be increased to 99% or more.

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

In the present invention, as the reaction solvent, butane, pentane, 3-methylpentane, hexane, heptane, 2-methylhexane, octane, cyclohexane,
A chain or alicyclic saturated hydrocarbon having 1 to 20 carbon atoms such as methylcyclohexane and decalin, and aromatic hydrocarbon such as benzene, toluene, xylene, ethylbenzene, mesitylene, and tetralin are used. These may be used alone or as a mixed solvent.

Further, as the reaction solvent, the α-olefin itself as a reaction raw material or an α-olefin other than the main raw material can be used. The α-olefin can also be incorporated into the catalyst system as a catalyst component before the start of the low polymerization reaction. As the reaction solvent, an α-olefin having 4 to 30 carbon atoms is used, and an α-olefin which is liquid at room temperature is particularly preferable.

Particularly, as the solvent, a chain saturated hydrocarbon having 4 to 7 carbon atoms or an alicyclic saturated hydrocarbon is preferable.
By using these solvents, there is an advantage that the by-product of the polymer can be suppressed and, when an alicyclic saturated hydrocarbon is used, high catalytic activity can be obtained. The reaction temperature is generally 0 to 250 ° C., preferably 10
The temperature is 150 ° C, more preferably 20 to 100 ° C. On the other hand, the reaction pressure can be usually selected from the range of 3 to 250 kg / cm ² , but preferably about 5 to 100 kg / c.
The pressure is m ² . The residence time is usually in the range of 1 minute to 20 hours, preferably 0.5 to 6 hours.
The reaction system may be a batch system, a semi-batch system or a continuous system.

If hydrogen is allowed to coexist during the reaction,
It is preferable because the catalytic activity and the selectivity of the trimer are improved. The amount of hydrogen to coexist is usually 0.1 to 100 kg / cm ² , preferably 1 to 80 kg as a hydrogen partial pressure.
The range is / cm ² . Separation and removal of the by-produced polymer in the reaction solution is carried out by appropriately using a known solid-liquid separation device, and the recovered α-olefin low polymer is purified if necessary. For purification, distillation purification is usually adopted,
In the present invention, since the amount of halogen-containing compound used is small and the decomposition products are small, the target component can be recovered in high purity. In the present invention, in particular, highly pure 1-hexene can be industrially advantageously produced from ethylene.

[0058]

EXAMPLES Hereinafter, specific embodiments of 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 the gist thereof is exceeded. Example 1 A 2 L autoclave that had been heated and dried in a dryer at 120 ° C. was assembled while hot, and the atmosphere was replaced with vacuum nitrogen. The autoclave was equipped with a catalyst feed tube equipped with a rupture plate having a pressure resistance of 5 kg / cm ² G. Cyclohexane (730
ml), 2,5-dimethylpyrrole (0.140 mmo
l) in n-heptane, 1,1,2,2-tetrachloroethane (15.7 mg, 0.093 mmol) in n-
Heptane solution, and triethylaluminum (0.7
0 mmol) of n-heptane solution was charged to the autoclave barrel side in this order, while the catalyst feed tube was charged with chromium (II
I) -2-Ethylhexanoate (22.5 mg, 0.0
47 mmol) of n-heptane solution was charged. The total amount of n-heptane was 20 ml. At this point, there is no contact between the chromium compound and triethylaluminum.

First, the autoclave is heated to 80 ° C.,
Next, ethylene was introduced from the catalyst feed pipe at 80 ° C. The rupture disk ruptured due to ethylene pressure, and the chromium compound was introduced into the autoclave barrel side to start low polymerization of ethylene. Ethylene was introduced until the total pressure reached 35 kg / cm ² , then the total pressure was maintained at 35 kg / cm ² and the reaction temperature was maintained at 80 ° C.

After a predetermined reaction time, each reaction solution was sampled. After the reaction, the pressure of the autoclave was released and degassing was performed, and then the by-product polymer (mainly polyethylene) in the reaction solution was recovered by a filter. The results of the composition analysis of the α-olefin low polymer by gas chromatography are shown in Table-1.

Comparative Example 1 Instead of 1,1,2,2-tetrachloroethane
Rumanium (GeCl _Four  20.0 mg, 0.093 m
mol) was used, and the reaction was performed in the same manner as in Example 1.
went. The results are shown in Table-2. Comparative example 2 Carbon tetrachloride instead of 1,1,2,2-tetrachloroethane
Elementary (CCl_Four  14.4 mg, 0.093 mmol)
The reaction was performed in the same manner as in Example 1 except that it was used. Conclusion
The results are shown in Table-3.

Example 2 The amount of 1,1,2,2-tetrachloroethane used was 39.
The reaction was performed in the same manner as in Example 1 except that the amount was 2 mg (0.234 mmol). The results are shown in Table-4. Example 3 The reaction was performed in the same manner as in Example 2 except that n-heptane (750 ml) was used as the solvent. The results are shown in Table-5.

Example 4 A reaction was carried out in the same manner as in Example 3 except that the amount of each catalyst component used was changed as shown in Table-6. The results are shown in Table-6.
Shown in. Example 5 1,1, instead of 1,1,2,2-tetrachloroethane
1-trichloroethane (12.1 mg, 0.093 mm
reaction was performed in the same manner as in Example 3 except that The results are shown in Table-7.

In each table, the solvent type "HP" represents n-heptane, "CHX" represents cyclohexane, and the Cr compound type Cr (2EHA) ₃ represents chromium (III) -2-ethylhexanoate. 2,5-DMPy is 2,5-
Represents dimethylpyrrole. The unit of catalyst efficiency is g
-Α-olefin / g-chromium, the unit of catalytic activity is g
-Α-olefin / g-chromium · hr. The content of chromium metal in the chromium compound used in the present invention was 10.4 wt% (analytical value).

[0065]

[Table 1]

[0066]

[Table 2]

[0067]

[Table 3]

[0068]

[Table 4]

[0069]

[Table 5]

[0070]

[Table 6]

[0071]

[Table 7]

[0072]

According to the method of the present invention, an α-olefin low polymer such as 1-hexene can be produced industrially advantageously in a high yield and a high selectivity without a complicated operation. It has a high industrial utility value in that the deterioration of activity over time can be significantly improved.

─────────────────────────────────────────────────── ─── Continuation of front page (51) Int.Cl. ⁷ Identification code FI C10G 50/00 C10G 50/00 // C07B 61/00 300 C07B 61/00 300 (72) Inventor Takeshi Okano Ushio Kurashiki, Okayama Prefecture Tsudori 3-chome 10 Mizushima Development Laboratory, Mitsubishi Kagaku Co., Ltd. (56) Reference JP-A-8-3216 (JP, A) JP-A-8-151409 (JP, A) JP-A-6-239920 (JP, A) (58) Fields investigated (Int.Cl. ⁷ , DB name) C08F 4/60-4/70 C07C 2/00-2/88

Claims (11)

(57) [Claims] 1. A method for producing an α-olefin low polymer using a chromium-based catalyst, wherein the chromium-based catalyst is:
From a combination of at least one catalytic amount of a chromium compound (a), at least one nitrogen-containing compound (b) selected from the group consisting of amines, amides and imides, an alkylaluminum compound (c) and a halogen-containing compound (d). Of the above components (a) to
Before the low polymerization reaction is initiated by the simultaneous presence of (d) and the α-olefin, each of the above-mentioned components (a) in such a manner that the chromium compound (a) and the alkylaluminum compound (c) do not come into contact with each other. To (d) are supplied to the reaction system and contacted with α-olefin to produce an α-olefin low polymer, wherein the halogen-containing compound (d) is substituted with 3 or more halogen atoms. A process for producing an α-olefin low polymer, which is a linear hydrocarbon having 2 or more carbon atoms. 2. The method for producing an α-olefin low polymer according to claim 1, wherein the linear hydrocarbons are saturated hydrocarbons. 3. The α-olefin-containing compound according to claim 1 or 2, wherein the halogen-containing compound (d) is a straight chain hydrocarbon in which two adjacent carbon atoms are substituted with three or more halogen atoms. Method for producing polymer. 4. The method for producing an α-olefin low polymer according to claim 3, wherein the halogen-containing compound (d) is represented by the following general formula (I). [Chemical 1] (In the general formula (I), X _{1 to} X ₈ each independently represent a hydrogen atom or a halogen atom, at least three of X _{1 to} X ₅ are halogen atoms, and 1 is 0 to 8). .) 5. The method for producing an α-olefin low polymer according to claim 3, wherein the halogen-containing compound (d) is represented by the following general formula (II). [Chemical 2] (In the general formula (II), Hal _{1 to} Hal ₃ represent a halogen atom, X _{9 to} X ₁₃ are each independently a halogen atom or a hydrogen atom, and m is 0 to 8.) 6. The method for producing an α-olefin low polymer according to claim 3, wherein the halogen-containing compound (d) is represented by the following general formula (III). [Chemical 3] (In the general formula (III), Hal _{4 to} Hal ₇ represent a halogen atom, X _{14 to} X ₁₇ are each independently a halogen atom or a hydrogen atom, and n is 0 to 8.) 7. The method for producing an α-olefin low polymer according to claim 1, wherein the chromium compound (a) and the alkylaluminum compound (c) are brought into contact with the α-olefin simultaneously during the low polymerization reaction. . 8. An α-olefin and a chromium compound (a) are introduced into a solution containing a halogen-containing compound (d), a nitrogen-containing compound (b) and an alkylaluminum compound (c). The method for producing an α-olefin low polymer according to 1. 9. An α-olefin, a halogen-containing compound (d) and a chromium compound (a) in a solution containing a nitrogen-containing compound (b) and an alkylaluminum compound (c).
The method for producing an α-olefin low polymer according to claim 1, wherein: 10. The α-olefin is ethylene, and α
-The olefin low polymer is mainly 1-hexene, The manufacturing method of the alpha olefin low polymer in any one of Claims 1-9. 11. A method for producing an α-olefin low polymer using a chromium-based catalyst, wherein the chromium-based catalyst is at least a chromium compound (a), an amine or metal amide (b), and an alkylaluminum compound (c). And a halogen-containing compound (d) in the form of a catalytic system, and a chromium compound (a) in a reaction solvent.
A method of producing an α-olefin low polymer by contacting an α-olefin with a chromium-based catalyst in such a manner that the alkylaluminum compound (c) and the alkylaluminum compound (c) do not previously contact,
The method for producing an α-olefin low polymer, wherein the halogen-containing compound (d) is a linear hydrocarbon having 2 or more carbon atoms and substituted with 3 or more halogen atoms.