JP3388975B2 - Method for producing low α-olefin 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, and more particularly, to an α-olefin low polymer mainly containing 1-hexene from ethylene in a high yield. 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, by any of the above-mentioned methods, the by-product of the polymer is unavoidable. In particular, in the industrial production method of the α-olefin low polymer, the method of producing the by-product polymer is determined. It is an important issue to separate them. The present invention has been made in view of such circumstances, and an object thereof is a method for producing an α-olefin low polymer using a chromium-based catalyst, in which a by-product polymer is efficiently produced by a compact process. It is an object of the present invention to provide an industrially advantageous method for producing an α-olefin low polymer which is improved so that it can be separated.

[0005]

That is, the gist of the present invention is, in a method for producing an α-olefin low polymer using a chromium-based catalyst, at least as a chromium-based catalyst,
Low polymerization of α-olefin in a solvent using a catalyst system comprising a combination of a chromium compound (a), one or more compounds (b) selected from the group of amines, amides and imides, and an alkylaluminum compound (c). And then
A method for producing an α-olefin low polymer, which comprises distilling and separating each component from a reaction solution and concentrating and separating a by-product polymer together with a catalyst component.

[0006]

BEST MODE FOR CARRYING OUT THE INVENTION The present invention will be described in detail below.
In the present invention, as the chromium-based catalyst, at least,
A catalyst system consisting of a combination of a chromium compound (a), one or more compounds (b) selected from the group of amines, amides and imides and an alkylaluminum compound (c) is used. And, in a preferred embodiment, 1 selected from the group of chromium compound (a), amine, amide and imide
A catalyst system consisting of a combination of one or more compounds (b), an alkylaluminum compound (c) and a halogen-containing compound (d) is used.

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.

The 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) -t- 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)
_{Naphthenates, Cr (CH 3 COCHCOOCH 3)} 3,
Chromium chloride, Chromium chloride, Chromium bromide, Chromium bromide, Chromium iodide, Chromium iodide,
Chromium fluoride, chromic fluoride, etc. may be mentioned.

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 nitrile, amine, amide, 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.

As the phosphorus-containing compound, hexamethylphosphoamide, hexamethylphosphorus triamide, triethylphosphite, tributylphosphine oxide,
Examples include triethylphosphine and the like. On the other hand, as the sulfur-containing compound, carbon disulfide, dimethyl sulfoxide,
Examples include tetramethylene sulfone, thiophene, dimethyl sulfide and the like.

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 diethylpyrrolid, ethylaluminum dipyrrolide, aluminum tripyrrolid and the like.

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 a secondary amine, aluminum pyrrolide, ethylaluminum dipyrrolide, aluminum tripyrolide, sodium pyrrolide, lithium pyrrolide and potassium pyrrolide are preferable. And
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).

[0021]

[Chemical 1]

In the general formula (1), M ¹ is a hydrogen atom or a metal element selected from the groups IA, IIA and IIIB of the periodic table, and R ¹ 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 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 the amides represented by the general formula (1) or the general formula (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.

Examples of the sulfonamides and sulfonimides represented by the general formula (3) include 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,
R ² in the general formula (1) represents an acyl group C (═O) R ³ >
However, an imide compound in which 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.

[0028]

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-mentioned alkylaluminum compounds 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.

[0031]

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 above alkylaluminum compounds 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, diethylaluminum chloride, ethylaluminum 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.

Of 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 bring the α-olefin into contact with the chromium-based catalyst in such a manner that the chromium compound (a) and the alkylaluminum compound (c) do not come into 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 a chromium compound and an 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 clear yet, 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, as the raw material 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. 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 the 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 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 by-produced polymer is concentrated and separated together with the catalyst component. Separation and removal of the by-produced polymer can be carried out by a solid-liquid separator, but in that case, not only a solid-liquid separator for the by-produced polymer is required in addition to the separation of the metal component, but also in the reaction solution. The separation of the metallized metal component becomes extremely difficult due to the heat history received during the distillation separation of each component. That is,
For example, when the heating evaporator is used to separate the high boiling point component and the metal component, the metal component adheres to the heat transfer surface of the heating evaporator and is substantially inseparable. The metal component attached to the heat transfer surface hinders the operation of the heating evaporator. On the other hand, in the case of the present invention, since the by-product polymer is concentrated and separated together with the catalyst component, the catalyst component is very easily separated by the plasticity of the by-product polymer. Moreover, the solid-liquid separation device for the by-product polymer can be omitted, and the process can be made compact.

In the present invention, the concentration and separation of the by-produced polymer and the catalyst component can be carried out at the same time that all components having a low boiling point are removed from the degassed reaction solution by simple distillation.
It can also be carried out at the same time as the final distillation separation when the respective components are sequentially distilled off from the degassed reaction solution. For example, α
-When olefin is ethylene, 1-hexene is obtained as an α-olefin low polymer. In this case, after the reaction, deethylene is carried out, and then 1-hexene and the solvent are distilled off from the reaction solution and the catalyst is used. The components are concentrated and separated with the by-product polyethylene. Then, the obtained concentrated liquid containing the by-product polymer and the catalyst component can be discarded as it is.

Further, in the present invention, at least a part of each of the by-product polymer and the catalyst component is simultaneously separated, but preferably all of the catalyst component, more preferably all of the by-product polymer and the catalyst component are simultaneously separated. Perform separation. In any case, it is preferable that the catalyst component separated and concentrated together with the by-product polymer in the distillation separation operation is further concentrated and recovered by the heating evaporator.

As the heating evaporator, various conventionally known ones can be used. For example, a thin film evaporator equipped with a scraping blade that rotates with respect to a heat transfer surface of a cylinder type,
An evaporator having a plate fin type heater incorporated therein may be used. Evaporator with built-in plate fin type heater,
The high-viscosity fluid can be instantly heated by the fins arranged at high density, and the volatile substances contained therein can be efficiently removed. Examples of the heating evaporator having such a structure include “Hibiscus evaporator” (trade name) manufactured by Mitsui Shipbuilding Co., Ltd. When the “Hibiscus evaporator” is used, the by-product polymer and the catalyst component concentrated by the built-in plate fin type heater flow down from the lower part of the “Hibiscus evaporator” due to the plasticity of the by-product polymer. Therefore, it can be easily recovered by cutting in an appropriately cooled state.

In the present invention, a particularly recommended heating evaporator is a monotube evaporator having a heating tube having a sufficient length and a collecting can capable of holding a reduced pressure. Examples of the heating evaporator having such a structure include “CRUX SYSTEM” (trade name) manufactured by Hosokawa Mikaron Co., Ltd. This monotube type evaporator
The concentrated liquid heated and evaporated by the heating pipe is ejected to the collecting can at a high speed of sound speed to efficiently remove the volatile substances contained therein. The by-product polymer and the catalyst component concentrated in the collecting can flow down from the lower part of the collection chamber due to the plasticity of the by-product polymer. Therefore, it can be easily recovered by cutting in an appropriately cooled state.

On the other hand, the recovered α-olefin low polymer is purified if necessary. Distillation purification is usually employed for purification, and 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. 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.

[0054]

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 complete mixing tank type reactor, a degassing tank, an ethylene distillation column, a hexene distillation column, a heptane distillation column and an evaporator were used, and degassing was performed between the reactor and the degassing tank. A continuous low polymerization reaction of ethylene was carried out according to a process equipped with a compressor for circulating ethylene in the reactor. A 20 L autoclave equipped with two supply pipes was used as the complete mixing tank reactor, and a “Hibiscus evaporator” (trade name, manufactured by Mitsui Engineering & Shipbuilding Co., Ltd.) was used as an evaporator. Also,
The ethylene distillation column has 15 stages, and the hexene distillation column and the heptane distillation column each have 20 stages.

From one supply pipe of the complete mixing tank reactor, n-heptane solution of chromium (III) 2-ethylhexanoate and 1,1,2,2-tetrachloroethane and n-heptane solution together with ethylene were supplied. Was continuously supplied, and the n-heptane solution of 2,5-dimethylpyrrole and the n-heptane solution of triethylaluminum were continuously supplied from the other supply pipe.

The reaction liquid continuously withdrawn from the reactor was supplied to the degassing tank. The degassed reaction liquid was sequentially processed in an ethylene distillation column, a hexene distillation column, and a heptane distillation column. The bottom liquid of the heptane distillation column was supplied to the evaporator and concentrated. In the evaporator, the evaporated high boiling point component was condensed and recovered, and the catalyst component concentrated with the by-product polyethylene was recovered as a solid content after cooling. On the other hand, ethylene degassed in the degassing tank is pressurized in the compressor and circulated in the reactor, and n-heptane separated in the heptane distillation column is circulated in the reactor through the circulation pipe. Was done.

Table 1 shows the operating conditions of each unit in the above process. Table 2 shows the mass balance in the above process. In addition, Cr (2EHA) ₃ in Table 2 represents chromium (III) 2-ethylhexanoate.

[0059]

Table 1 Reactor: 80 ° C. × 35 Kg / cm ² G Degassing tank: 40 ° C. × 5 Kg / cm ² G Ethylene distillation column: Column top pressure 5 Kg / cm ² G Reflux ratio (R / D) 0.5 Hexene Distillation tower: Tower top pressure 760 mmHg Reflux ratio (R / D) 3.0 Heptane Distillation tower: Tower top pressure 760 mmHg Reflux ratio (R / D) 3.0 Evaporator: Heat transfer area 0.125 m ² Heater temperature 230 ° C Flash Drum pressure 100mmHg

[0060]

[Table 2] ──────────────────────────────────── Reaction liquid Degassing liquid Dehydrous heptane liquid High boiling point Ingredients Solid content ──────────────────────────────────── Unit: / Hr 26.1Kg 22.6Kg 1.31Kg 1.30 Kg 2.8g ──────────────────────────────────── Cr (2EHA) ₃ (ppm) 20.0 23.1 120 − 5.66wt% 2,5-Dimethylprolol (ppm) 11.9 13.7 71.1 71.2 − Triethylaluminum (ppm) 71.1 82.3 427 − 20.1wt% Tetrachloroethane (ppm) 34.9 40.3 209 209 − Heptane (wt%) 30.9 35.8 − − − Ethylene (wt%) 13.6 − − − − 1-Hexene (wt%) 50.5 58.4 − − − High boiling point component (wt%) 4.99 5.77 99.8 99.9 − Polyethylene (ppm) 105 109 1574 − 74.2wt% ──── ──────────────────────────── ─────

In the operation of the evaporator in the above process, since the catalyst component containing the metal is a mixture concentrated with the by-product polyethylene, the plasticity of the polyethylene causes it to fall and separate from the heat transfer surface by its own weight and then to be cooled and solidified. It was

Example 2 Example 1 was repeated except that chloroform was used instead of 1,1,2,2-tetrachloroethane in Example 1.
A continuous low polymerization reaction of ethylene was carried out under the same conditions as in. Table 3 shows the mass balance in the same process as in Example 1. The operation in the above process is the same as in Example 1.
Stable and continuous operation was possible.

[0063]

[Table 3] ──────────────────────────────────── Reaction solution Degassed solution Degassed heptane solution High boiling point Ingredients Solid content ──────────────────────────────────── Unit: / Hr 35.0Kg 30.3Kg 1.45Kg 1.42 Kg 28.7g ──────────────────────────────────── Cr (2EHA) ₃ (ppm) 22.0 25.4 159 − 0.80wt% 2,5-Dimethylprolol (ppm) 13.0 15.1 94.2 96.1 − Triethylaluminum (ppm) 78.2 90.5 565 − 2.86wt% Tetrachloroethane (ppm) 38.3 44.3 277 283 − Heptane (wt%) 41.3 47.8 − − − Ethylene (wt%) 13.6 − − − − 1-Hexene (wt%) 41.0 47.4 − − − High boiling point component (wt%) 4.07 4.71 98.0 99.9 − Polyethylene (ppm) 1054 1097 1.90wt% − 96.3wt% ── ──────────────────────────── ───────

Example 3 In Example 2, as an evaporator, a monotube type evaporator "CRUX SYSTEM" (Hosokawa Mikaron Co., Ltd.) equipped with a heating tube having a length of 8 m and a collecting can capable of holding a reduced pressure was used.
A continuous low polymerization reaction of ethylene was carried out under the same conditions as in Example 2 except that the trade name (product name) was used. The operating conditions of the evaporator are as follows: heating tube temperature: 200 ° C, collector temperature: 150 ° C,
A collecting can pressure of 200 torr was adopted. Table 4 shows the mass balance in the same process as in Example 1. The operation in the above process could be stably and continuously operated as in Examples 1 and 2.

[0065]

[Table 4] ──────────────────────────────────── Reaction solution Degassed solution Degassed heptane solution High boiling point Ingredients Solid content ──────────────────────────────────── Unit: / Hr 36.1Kg 31.2Kg 1.53Kg 1.45 Kg 82.5g ──────────────────────────────────── Cr (2EHA) ₃ (ppm) 26.0 30.1 184 − 0.341wt% 2,5-Dimethylprolol (ppm) 15.4 17.8 109 116 − Triethylaluminum (ppm) 92.5 107 656 − 1.21wt% Tetrachloroethane (ppm) 45.3 52.5 321 340 − Heptane (wt%) 41.1 47.6 − − − Ethylene (wt%) 13.6 − − − − 1-Hexene (wt%) 41.0 47.4 − − − High boiling point component (wt%) 4.07 4.63 94.6 99.9 − Polyethylene (ppm) 3000 3125 5.32wt% − 98.4wt% ── ──────────────────────────── ──────

Comparative Example 1 Example 1 was repeated except that a filter was placed between the degassing tank and the ethylene distillation column, and the degassed reaction solution was filtered to separate by-product polyethylene. Same as 1
-Hexene was produced continuously. During the operation of the evaporator, continuous operation could not be performed because the catalyst component including metal was converted into Harz and adhered to the heat transfer surface.

[0067]

According to the present invention described above, a method for producing an α-olefin low polymer using a chromium-based catalyst, wherein a by-produced polymer can be efficiently separated by a compact process. An industrially advantageous method for producing an improved α-olefin low polymer is provided.

─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Akio Tsuboi, 3-10-10, Shiodotsu, Kurashiki-shi, Okayama Mitsubishi Kagaku Co., Ltd. Mizushima Plant (56) Reference JP-A-7-10780 (JP, A) JP Flat 4-66457 (JP, B2) (58) Fields investigated (Int.Cl. ⁷ , DB name) C07C 2/06-2/36 C07C 11/107-11/113 C08F 4/69

Claims (10)

(57) [Claims] 1. A method for producing an α-olefin low polymer using a chromium-based catalyst, wherein the chromium-based catalyst contains at least a chromium compound (a), an amine (b) , an alkylaluminum compound (c) and a reaction solvent. Soluble and Periodic Table IIIA, IIIB, IVA, IV
Using a catalyst system comprising a combination of a halogen-containing compound (d) containing an element selected from the group consisting of B, VA and VB, low polymerization of α-olefin was carried out in a solvent, and the resulting α-olefin low-weight A method for producing an α-olefin low polymer, characterized in that the combined product is separated by distillation from the reaction liquid, and the by-product polymer in the reaction liquid is concentrated and separated together with the catalyst component. 2. A method for producing α- olefin low polymer of amine according to claim 1 is one or more of the pyrrole and / or pyrrole derivatives. 3. The method for producing an α-olefin low polymer according to claim 1, wherein the halogen of the halogen-containing compound (d) is chlorine or bromine. 4. 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 in any one of Claims 1-3. 5. The low polymerization of α-olefin is carried out by bringing α-olefin into contact with a chromium-based catalyst in such a manner that the chromium compound (a) and the alkylaluminum compound (c) do not come into contact with each other in advance. The method for producing an α-olefin low polymer according to any one of claims 1. 6. The α-olefin low polymer according to claim 1, wherein the catalyst component separated and concentrated together with the by-product polymer in the distillation separation operation is further concentrated and recovered in a heating evaporator. Production method. 7. The α-olefin low polymer according to claim 6, wherein the heating evaporator is a monotube type evaporator having a heating tube having a sufficient length and a collecting can capable of holding under reduced pressure. Production method. 8. The α-olefin is ethylene, and α-olefin is
The olefin polymer is mainly 1-hexene, and after the reaction, ethylene is removed, and then 1-hexene and the solvent are distilled off from the reaction solution, and the catalyst component is concentrated by separation with polyethylene as a by-product. Items 1-7
9. The method for producing an α-olefin low polymer according to any one of 1. 9. The low-gravity reaction is carried out in the presence of hydrogen.
9. The method for producing an α-olefin low polymer according to any one of items 8 to 8. 10. The halogen-containing compound (d) is scandium chloride, yttrium chloride, lanthanum chloride, titanium tetrachloride, zirconium tetrachloride, hafnium tetrachloride, boron trichloride, aluminum chloride, diethylaluminum chloride, ethylaluminum sesquichloride, Gallium chloride, carbon tetrachloride, chloroform, methylene chloride, dichloroethane, trichloroethane, tetrachloroethane, hexachlorobenzene, 1,3,5-trichlorobenzene, hexachlorocyclohexane, trityl chloride,
Silane tetrachloride, trimethylchlorosilane, germanium tetrachloride, tin tetrachloride, tributyltin chloride, phosphorus trichloride, antimony trichloride, trityl hexachloroantimonate, antimony pentachloride, bismuth trichloride, boron tribromide, aluminum tribromide, tetra The α-olefin low polymer according to claim 1 or 2, which is one or more selected from the group consisting of carbon bromide, bromoform, bromobenzene, iodomethane, silicon tetrabromide, hexafluorobenzene, and aluminum fluoride. Manufacturing method.