JP2012188371A - PRODUCTION METHOD OF α-OLEFIN OLIGOMER - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a method for efficiently and stably producing an α-olefin oligomer at a low cost in a method of producing an α-olefin oligomer by causing a raw material α-olefin to oligomerization reaction.SOLUTION: The method for producing the α-olefin oligomer by using a catalyst formed of a transition metal containing compound, a nitrogen-containing compound and an aluminum-containing compound, includes steps of: continuously supplying raw material α-olefin to a reactor; causing the raw material α-olefin to oligomerization reaction in the reactor in the presence of a solvent to produce the α-olefin oligomer; continuously extracting a reaction liquid containing the α-olefin oligomer from the reactor; separating the solvent from the reaction liquid; and continuously circulating and supplying the separated solvent to the reactor. The concentration of the nitrogen-containing compound in the solvent circulated and supplied in a steady state is 5.0 ppm by weight or more.

Description

  The present invention relates to a method for producing an α-olefin low polymer by subjecting a raw material α-olefin to a low polymerization reaction, and more specifically, a method for producing 1-hexene by ethylene trimerization reaction using ethylene as a raw material. About.

  The α-olefin low polymer is useful as a raw material monomer for olefin polymers (polymers), as a comonomer for various polymers, and as a raw material for plasticizers, surfactants, lubricating oils and the like. It is a substance. The α-olefin low polymer can be obtained by subjecting the raw material α-olefin to a low polymerization reaction in the presence of a solvent using a homogeneous catalyst formed from a transition metal-containing compound.

  As a method for producing 1-hexene, which is a trimer of ethylene, using ethylene as a raw material, for example, a catalyst system comprising a combination of a chromium compound and an amine or a metal amide and an alkylaluminum compound is used, and α- A method of performing low polymerization of olefin, distilling and separating α-olefin low polymer from the obtained reaction liquid, and circulating the recovered catalyst component-containing solvent to the reaction system (Japanese Patent Laid-Open No. 7-149673), or completely In a process consisting of a mixing tank reactor, degassing tank, ethylene distillation tower, hexene distillation tower, heptane distillation tower, and evaporator, a continuous low polymerization reaction of ethylene is carried out using n-heptane as a solvent, and from the reactor A method in which n-heptane that flows out is separated in a heptane distillation column, and the separated n-heptane is circulated to the reactor through a circulation pipe (JP-A-8-2). No. 39419) is known.

JP-A-7-149673 JP-A-8-239419

When the α-olefin low polymer is produced by the method described in Patent Document 1, a byproduct or a modified catalyst having a boiling point higher than that of the α-olefin low polymer as the target product in the solvent circulating to the reaction system. There was a problem that the components were accumulated, the selectivity of the target α-olefin low polymer was lowered, and the by-product polymer was increased.
Patent Document 2 describes a heptane separation tower so that by-products having a higher boiling point and altered catalyst components do not accumulate in the solvent circulating to the reaction system than the α-olefin low polymer as the target product. However, there is a problem that the catalyst activity gradually decreases when continuously operated by this method.

  This invention is made | formed in view of the said subject, Comprising: Raw material alpha-olefin using the catalyst formed from a transition metal containing compound, a nitrogen containing compound, and an aluminum containing compound is low-polymerized, and an alpha-olefin low polymer is made. An object of the present invention is to provide a method for producing an α-olefin low polymer stably at a low cost and efficiently.

As a result of intensive studies to solve the above problems, the inventors of the present invention, in a process for producing an α-olefin low polymer having a step of circulating a solvent, contained a nitrogen-containing compound as one of the catalyst components in the circulating solvent. It has been found that the presence of a certain amount in the catalyst can improve the catalyst activity without lowering the catalyst activity under steady operation and can suppress the generation of by-product polymers.
The present invention has been achieved on the basis of such findings, and the gist thereof is as follows [1] to [8].
[1] Using a catalyst formed from a transition metal-containing compound, a nitrogen-containing compound and an aluminum-containing compound, a raw material α-olefin is continuously supplied to the reactor, and the raw material α is present in the reactor in the presence of a solvent. -Low polymerization reaction of olefin to produce an α-olefin low polymer, and a reaction liquid containing the α-olefin low polymer was continuously withdrawn from the reactor, and the solvent was separated from the reaction liquid and separated. A method for producing an α-olefin low polymer in which the concentration of a nitrogen-containing compound in a solvent to be circulated in a steady state is 5.0 wtppm or more when the solvent is continuously circulated to the reactor.
[2] When separating a by-product having a boiling point higher than that of the target α-olefin polymer from the reaction solution, distillation is performed using a distillation column and the reflux ratio is set to 1.0 or less. The method for producing an α-olefin low polymer as described in [1].
[3] The method for producing an α-olefin low polymer according to [1] or [2], wherein the nitrogen-containing compound is a pyrrole-containing compound.
[4] The method for producing an α-olefin low polymer according to any one of [1] to [3], wherein the transition metal-containing compound contains a transition metal of Groups 4 to 6 in the periodic table. .
[5] The transition metal-containing compound contains one or more metals selected from the group consisting of chromium, titanium, zirconium, vanadium, and hafnium, and any one of [1] to [4] The manufacturing method of the alpha-olefin low polymer of description.
[6] The method for producing an α-olefin low polymer according to any one of [1] to [5], wherein the catalyst further contains a halogen-containing compound.
[7] The method for producing an α-olefin low polymer according to any one of [1] to [6], wherein the solvent is a saturated hydrocarbon.
[8] The method for producing an α-olefin low polymer according to any one of [1] to [7], wherein the α-olefin is ethylene and the α-olefin low polymer is 1-hexene.

  According to the present invention, it is possible to suppress a decrease in catalyst activity in continuous operation and improve the catalyst activity in a steady state. In addition, by-product polyethylene can be reduced.

It is a systematic diagram which shows embodiment of the manufacturing method of the alpha-olefin low polymer of this invention.

The description of the constituent requirements described below is an example (representative example) of an embodiment of the present invention, and the present invention is not limited to these contents. The details will be described below.
(catalyst)
The catalyst used in the present invention is not particularly limited as long as it is a catalyst capable of producing a low α-olefin polymer by low polymerization reaction of α-olefin, but at least as a catalyst component a transition metal-containing compound, a nitrogen-containing compound and aluminum. A catalyst system comprising a combination of each catalyst component of the contained compound is used. Moreover, it is preferable to further contain a halogen-containing compound in addition to these three catalyst components.

(Transition metal-containing compounds)
In the method for producing an α-olefin low polymer to which the present embodiment is applied, the transition metal-containing compound used as one of the components constituting the catalyst is not particularly limited as long as it is a compound containing a transition metal, Among them, transition metals belonging to Groups 4 to 6 of the periodic table are preferably used. Specifically, it is preferably at least one metal selected from the group consisting of chromium, titanium, zirconium, vanadium and hafnium, more preferably chromium or titanium, and most preferably chromium.

  In the present invention, the transition metal-containing compound used as a raw material for the catalyst is one or more compounds represented by the general formula MeZn. Here, in the general formula, Me is a transition metal element, Z is any organic group, inorganic group, or negative atom, n is an integer of 1 to 6, and 2 or more is preferable. When n is 2 or more, Z may be the same or different from each other. The organic group may be a hydrocarbon group having 1 to 30 carbon atoms which may have a substituent, and specifically includes a carbonyl group, an alkoxy group, a carboxyl group, a β-diketonate group, a β-keto. Examples include a carboxyl group, a β-ketoester group, an amide group, and the like. In addition, examples of the inorganic group include metal salt forming groups such as a nitrate group and a sulfate group. Examples of negative atoms include oxygen and halogen. In addition, the transition metal containing compound containing a halogen is not contained in the halogen containing compound mentioned later.

In the case of a transition metal-containing compound whose transition metal is chromium (hereinafter sometimes referred to as a chromium-containing compound), specific examples include 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 (where Ph represents a phenyl group.), Chromium (II) acetate, chromium (III) acetate, chromium (III) 2-ethylhexanoate, chromium (III) benzoate, chromium (III) naphthenate, chromium (III) _{heptanoate, Cr (CH 3 COCHCOOCH 3)} 3, a first chromium chloride, chromic chloride, bromide first click Arm, bromide chromic, first chromium iodide, chromic iodide, first chromium fluoride, and the second chromium fluoride.

In the case of a transition metal-containing compound in which the transition metal is titanium (hereinafter sometimes referred to as a titanium-containing compound), specific examples include TiCl ₄ , TiBr ₄ , TiI ₄ , TiBrCl ₃ , TiBr ₂ Cl ₂ , Ti (OC _{2 H 5) 4, Ti (} OC 2 H 5) 2 Cl 2, Ti (O-n-C 3
_{H 7) 4, Ti (O} -n-C 3 H 7) 2 Cl 2, Ti (O-iso-C 3 H 7) 4, Ti (O-iso-C 3 H 7) 2 Cl 2, Ti ( _{O-n-C 4 H 9} ) 4, Ti (O-n-C 4 H 9) 2 Cl 2,
_{Ti (O-iso-C 4} H 9) 4, Ti (O-iso-C 4 H 9) 2 Cl 2, Ti (O-te
rt-C ₄ H ₉ ) ₄ , Ti (O-tert-C ₄ H ₉ ) ₂ Cl ₂ , TiCl ₄ (thf) ₂ (
In the chemical formula on the left, thf represents tetrahydrofuran), Ti ((CH ₃ ) ₂ N) ₄ , Ti (
_{(C 2 H 5) 2 N} ) 4, Ti ((n-C 3 H 7) 2 N) 4, Ti ((iso-C 3 H 7) 2 N) 4,
_{Ti ((n-C 4 H} 9) 2 N) 4, Ti ((tert-C 4 H 9) 2 N) 4, Ti (OSO 3 CH 3) 4, Ti (OSO 3 C 2 H 5) 4, Ti (OSO ₃ C ₃ H ₇ ) ₄ , Ti (OSO ₃ C ₄ H ₉ ) ₄ ,
TiCp ₂ Cl ₂ , TiCp ₂ ClBr, Ti (OCOC ₂ H ₅ ) ₄ , Ti (OCOC ₂ H ₅ ) ₂ Cl ₂ , Ti (OCOC ₃ H ₇ ) ₄ , Ti (OCOC ₃ H ₇ ) ₂ Cl ₂ , Ti (OCOC ₃ H ₇ ) ₄
Ti (OCOC ₃ H ₇ ) ₂ Cl ₂ , Ti (OCOC ₄ H ₉ ) ₄ , Ti (OCOC ₄ H ₉ ) ₂ Cl _{2 and the} like.

In the case of a transition metal-containing compound in which the transition metal is zirconium (hereinafter sometimes referred to as a zirconium-containing compound), specific examples include ZrCl ₄ , ZrBr ₄ , ZrI ₄ , ZrBr.
Cl ₃ , ZrBr ₂ Cl ₂ , Zr (OC ₂ H ₅ ) ₄ , Zr (OC ₂ H ₅ ) ₂ Cl ₂ , Zr ( _On )
_{-C 3 H 7) 4, Zr} (O-n-C 3 H 7) 2 Cl 2, Zr (O-iso-C 3 H 7) 4, Zr (O-iso-C 3 H 7) 2 Cl 2 _{Zr (O-n-C 4} H 9) 4, Zr (O-n-C 4 H 9) 2 Cl 2,
_{Zr (O-iso-C 4} H 9) 4, Zr (O-iso-C 4 H 9) 2 Cl 2, Zr (O-tert-C 4 H 9) 4, Zr (O-tert-C 4 H ₉ ) ₂ Cl ₂ , Zr ((CH ₃ ) ₂ N) ₄ ,
_{Zr ((C 2 H 5)} 2 N) 4, Zr ((n-C 3 H 7) 2 N) 4, Zr ((iso-C 3 H 7) 2 N) 4, Zr ((n-C 4 _{H 9) 2 N) 4,} Zr ((tert-C 4 H 9) 2 N) 4, Zr (OS
O ₃ CH ₃ ) ₄ , Zr (OSO ₃ C ₂ H ₅ ) ₄ , Zr (OSO ₃ C ₃ H ₇ ) ₄ , Zr (OSO ₃ C ₄ H ₉ ) ₄ , ZrCp ₂ Cl ₂ , ZrCp ₂ ClBr, Zr (OCOC ₂ H ₅ ) ₄ , Zr (OCOC ₂ H ₅ ) ₂ Cl ₂ , Zr (OCOC ₃ H ₇ ) ₄ , Zr (OCOC ₃ H ₇ ) ₂ Cl ₂ , Zr (OCOC ₃ H ₇ ) ₄ , Zr ( OCC ₃ H ₇ ) ₂ Cl ₂ , Zr (OCOC ₄ H ₉ ) ₄ , Zr (OCOC ₄ H ₉ ) ₂ Cl ₂ , ZrCl ₂ (HCOCFCOF) ₂ , ZrCl ₂ (CH ₃ COCFCOCH ₃ ) _{2 and the} like.

In the case of a transition metal-containing compound whose transition metal is hafnium (hereinafter sometimes referred to as a hafnium-containing compound), a specific example is dimethylsilylene bis {1- (2-methyl-4-isopropyl-4H-azurenyl)}. Hafnium dichloride, dimethylsilylenebis {1- (2-methyl-4-phenyl-4H-azurenyl)} hafnium dichloride, dimethylsilylenebis [1- {2-methyl-4- (4-chlorophenyl) -4H-azurenyl}] Hafnium dichloride, dimethylsilylenebis [1- {2-methyl-4- (4-fluorophenyl) -4H-azurenyl}] hafnium dichloride, dimethylsilylenebis [1- {2-methyl-4- (3-chlorophenyl)- 4H-azulenyl}] hafnium dichloride, dimethylsilylene bis [1 {2-Methyl-4- (2,6-dimethylphenyl) -4H-azurenyl}] hafnium dichloride, dimethylsilylenebis {1- (2-methyl-4,6-diisopropyl-4H-azurenyl)} hafnium dichloride, diphenyl Silylenebis {1- (2-methyl-4-phenyl-4H-azurenyl)} hafnium dichloride, methylphenylsilylenebis {1- (2-methyl-4-phenyl-4H-azurenyl)} hafnium dichloride, methylphenylsilylenebis [1- {2-Methyl-4- (1-naphthyl) -4H-azurenyl}] hafnium dichloride, dimethylsilylenebis {1- (2-ethyl-4-phenyl-4H-azurenyl)} hafnium dichloride, dimethylsilylenebis [1- {2-ethyl-4- (1-anthraceni ) -4H-azurenyl}] hafnium dichloride, dimethylsilylenebis [1- {2-ethyl-4- (2-anthracenyl) -4H-azurenyl}] hafnium dichloride, dimethylsilylenebis [1- {2-ethyl-4- (9-phenanthryl) -4H-azurenyl}] hafnium dichloride, dimethylmethylenebis [1- {2-methyl-4- (4-biphenylyl) -4H-azurenyl}] hafnium dichloride, dimethylgermylenebis [1- {2 -Methyl-4- (4-biphenylyl) -4H-azurenyl}] hafnium dichloride, dimethylsilylenebis {1- (2-ethyl-4- (3,5-dimethyl-4-trimethylsilylphenyl-4H-azurenyl)} hafnium Dichloride, dimethylsilyl 2 [1- {2-methyl-4- (4 -Biphenylyl) -4H-azurenyl}] [1- {2-methyl-4- (4-biphenylyl) indenyl}] hafnium dichloride, dimethylsilylene {1- (2-ethyl-4-phenyl-4H-azurenyl)} { 1- (2-methyl-4,5-benzoindenyl)} hafnium dichloride, dimethylsilylenebis {1- (2-methyl-4-phenylindenyl)} hafnium dichloride, dimethylsilylenebis {1- (2-methyl) -4,5-benzoindenyl)} hafnium dichloride, dimethylsilylene bis [1- {2-methyl-4- (1-naphthyl) indenyl}] hafnium dichloride, and the like.
Among these transition metal-containing compounds, chromium-containing compounds are preferable, and among chromium-containing compounds, chromium (III) 2-ethylhexanoate is particularly preferable.

(Aluminum-containing compound)
Examples of the aluminum-containing compound used in this embodiment include a trialkylaluminum compound, an alkoxyalkylaluminum compound, or an alkylaluminum hydride compound. Examples of the trialkylaluminum compound include trimethylaluminum, triethylaluminum, and triisobutylaluminum. Specific examples of the alkoxyaluminum compound include diethylaluminum ethoxide. Specific examples of the alkylaluminum hydride compound include diethylaluminum hydride. Among these, a trialkylaluminum compound is preferable,
More preferred is triethylaluminum. These compounds may be used as a single compound or as a mixture of a plurality of compounds.

(Nitrogen-containing compounds)
Examples of the nitrogen-containing compound used in this embodiment include amines, amides, and imides. Examples of amines include pyrrole skeleton-containing compounds, and specific examples thereof include pyrrole, 2,4-dimethylpyrrole, 2,5-dimethylpyrrole, 2,5-diethylpyrrole, 2,5-di-n-. Propyl pyrrole, 2,5-di-n-butyl pyrrole, 2,5-di-n-pentyl pyrrole, 2,5-di-n-hexyl pyrrole, 2,5-dibenzyl pyrrole, 2,5-diisopropyl pyrrole 2-methyl-5-ethylpyrrole, 2,5-dimethyl-3-ethylpyrrole, 3,4-dimethylpyrrole, 3,4-dichloropyrrole, 2,3,4,5-tetrachloropyrrole, 2-acetyl Examples include pyrrole, indole, 2-methylindole, pyrrole such as dipyrrole in which two pyrrole rings are bonded via a substituent, or derivatives thereof. Examples of the derivatives include metal pyrolide derivatives, and specific examples include, for example, diethylaluminum pyrolide, ethylaluminum dipyrrolide, aluminum tripyrolide, diethylaluminum (2,5-dimethylpyrrolide), ethylaluminum. Bis (2,5-dimethyl pyrolide), aluminum tris (2,5-dimethyl pyrolide), diethyl aluminum (2,5-diethyl pyrolide), ethyl aluminum bis (2,5-diethyl pyrolide), aluminum tris Aluminum pyrolides such as (2,5-diethyl pyrolide), sodium pyrolide, sodium pyrolides such as sodium (2,5-dimethyl pyrolide), lithium pyrolide, lithium (2,5-dimethyl pyrolide) ) Etc. Umupiroraido acids, potassium pyrrolide, potassium (2,5-dimethyl pyrrolide) potassium pyrrolide such like. Aluminum pyrolides are not included in the above-mentioned aluminum-containing compound. Further, the pyrrole compound containing halogen is not included in the halogen-containing compound described later.

Examples of amides include acetamide, N-methylhexanamide, succinamide, maleamide, N-methylbenzamide, imidazole-2-carboxamide, di-2-thenoylamine, β-lactam, δ-lactam, ε-caprolactam or Examples thereof include salts of these with metals of Group 1, 2 or 13 of the periodic table.
Examples of the imides include 1,2-cyclohexanedicarboximide, succinimide, phthalimide, maleimide, 2,4,6-piperidinetrione, perhydroazesin-2,10-dione, and 1 of the periodic table, And salts with Group 2 or 13 metals. Examples of the sulfonamides and sulfonamides include, for example, benzenesulfonamide, N-methylmethanesulfonamide, N-methyltrifluoromethylsulfonamide, and salts thereof with a metal of Groups 1 to 2 or 13 in the periodic table. Is mentioned. These compounds may be used as a single compound or a plurality of compounds.

In the present invention, among these, amines are preferable, among which pyrrole skeleton-containing compounds are more preferable, and 2,5-dimethylpyrrole is particularly preferable.
(Halogen-containing compounds)
The chromium-based catalyst used in the present embodiment includes a halogen-containing compound as a fourth component as necessary. Examples of the halogen-containing compound include a halogenated alkylaluminum compound, a benzyl chloride skeleton-containing compound, a linear halogen hydrocarbon compound having 2 or more carbon atoms having 3 or more halogen atoms, and a carbon having 3 or more halogen atoms. Examples thereof include cyclic halogen hydrocarbon compounds having a number of 3 or more. However, the halogenated alkyl aluminum compound is not included in the above-mentioned aluminum-containing compound.

Specific examples of the compound include diethylaluminum chloride, ethylaluminum sesquichloride, benzyl chloride, (1-chloroethyl) benzene, 2-methylbenzyl chloride, 3-methylbenzyl chloride, 4-methylbenzyl chloride, 4-ethylbenzyl. Chloride, 4-isopropylbenzyl chloride, 4-tert-butylbenzyl chloride, 4-vinylbenzyl chloride, α-ethyl-4-methylbenzyl chloride, α, α'-dichloro-o-xylene, α, α'-dichloro- m-xylene, α, α'-dichloro-p-xylene, 2,4-dimethylbenzyl chloride, 2,5-dimethylbenzyl chloride, 2,6-dimethylbenzyl chloride, 3,4-dimethylbenzyl chloride, 2,3 , 5,6-Tetramethylbenzyl chloride Lido, 1- (chloromethyl) naphthalene, 1- (chloromethyl) -2-methylnaphthalene, 1,4-bis-chloromethyl-2,3-dimethylnaphthalene, 1,8-bis-chloromethyl-2,3 , 4,5,6,7-hexamethylnaphthalene, 9- (chloromethyl) anthracene, 9,10-bis (chloromethyl) anthracene, 7- (chloromethyl) benzanthracene, 7-chloromethyl-12-methylbenz Anthracene, 1,1,1-trichloroethane, 1,1,2,2, -tetrachloroethane, pentachloroethane, hexachloroethane, 1,2,3-trichlorocyclopropane, 1,2,3,4,5,6- Examples include hexachlorocyclohexane, 1,4-bis (trichloromethyl) -2,3,5,6-tetrachlorobenzene.

(Α-olefin)
In the method for producing an α-olefin low polymer to which the present embodiment is applied, examples of the α-olefin used as a raw material include substituted or unsubstituted α-olefins having 2 to 30 carbon atoms. . Specific examples of such α-olefins include ethylene, propylene, 1-butene, 1-hexene, 1-octene, 3-methyl-1-butene, 4-methyl-1-pentene and the like. Among these, ethylene is suitable as the raw material α-olefin, and when ethylene is used as the raw material, 1-hexene, which is a trimer of ethylene, can be obtained with high yield and high selectivity. Moreover, when using ethylene as a raw material, impurity components other than ethylene may be included in the raw material. Specific components include methane, ethane, acetylene, carbon dioxide and the like. These components are preferably 0.1 mol% or less with respect to ethylene as a raw material.

(solvent)
In the method for producing an α-olefin low polymer to which the present embodiment is applied, the reaction of α-olefin can be carried out in a solvent. Although it does not specifically limit as such a solvent, A saturated hydrocarbon is used suitably, Preferably, for example, butane, pentane, 3-methylpentane, n-hexane, n-heptane, 2-methylhexane, octane, It is a C1-C20 chain saturated hydrocarbon or C1-C20 alicyclic saturated hydrocarbon such as cyclohexane, methylcyclohexane, 2,2,4-trimethylpentane, or decalin. Moreover, you may use aromatic hydrocarbons, such as benzene, toluene, xylene, ethylbenzene, mesitylene, and tetralin, as an α-olefin low polymer. These can be used alone or as a mixed solvent.

  Among these solvents, chain saturated hydrocarbons or fats having 4 to 10 carbon atoms from the viewpoint that production of by-products such as polyethylene can be suppressed, and that high catalytic activity tends to be obtained. It is preferable to use a cyclic saturated hydrocarbon, more preferably a saturated hydrocarbon having 5 to 7 carbon atoms such as n-heptane, cyclohexane or methylcyclohexane, and most preferably n-heptane.

(Pre-catalyst preparation)
In the present invention, the catalyst used for the low polymerization reaction is preferably such that the transition metal-containing compound and the aluminum-containing compound do not contact each other in advance, or the raw material α-olefin and the catalyst are contacted in such a manner that the contact time is short. . By such a contact mode, a low polymerization reaction of the raw material α-olefin can be selectively performed, and a low polymer of the raw material α-olefin can be obtained in a high yield. In the present invention, “an aspect in which the transition metal-containing compound and the aluminum-containing compound do not contact with each other in advance or the contact time is short in advance” refers not only to the start of the reaction but also to the raw material α-olefin and each catalyst thereafter. This means that the above-described embodiment is maintained even when the components are additionally supplied to the reactor. However, the specific embodiments described above are preferred embodiments required during catalyst preparation and are irrelevant after the catalyst is prepared. Therefore, when the catalyst already prepared is recovered from the reaction system and reused, the catalyst can be reused regardless of the above preferred embodiment.

The reason why the activity of the low polymerization reaction of the α-olefin is low when the catalyst is used in such a manner that the transition metal-containing compound and the alkylaluminum compound are in contact with each other is not yet clear, but is estimated as follows.
That is, when the transition metal-containing compound is brought into contact with the alkylaluminum, a ligand exchange reaction proceeds between the ligand coordinated to the transition metal-containing compound and the alkyl group in the alkylaluminum compound, It is considered unstable. Therefore, the decomposition-reduction reaction of the alkyl-transition metal-containing compound proceeds preferentially. As a result, metalization inappropriate for the low polymerization reaction of α-olefin occurs, and the activity of the low polymerization reaction of α-olefin decreases. .

  Therefore, when the catalyst is adjusted with the above four components, that is, the transition metal-containing compound (a), the nitrogen-containing compound (b), the aluminum-containing compound (c) and the halogen-containing compound (d), The contact mode is usually (1) a method of introducing the catalyst component (a) into a solution containing the catalyst components (b), (c) and (d), (2) a catalyst component (a), (b) And (d) a method of introducing the catalyst component (c) into the solution, and (3) a method of introducing the catalyst components (b) and (c) into the solution containing the catalyst components (a) and (d). (4) a method of introducing the catalyst components (a) and (b) into the solution containing the catalyst components (c) and (d), and (5) a solution containing the catalyst components (a) and (b). , A method of introducing the catalyst components (c) and (d), (6) a catalyst component in a solution containing the catalyst components (b) and (c). (A) a method for introducing (d), (7) a method for introducing catalyst components (a), (b) and (d) into a solution containing the catalyst component (c), (8) a catalyst component ( a method of introducing the catalyst components (b) to (d) into the solution containing a), (9) a method of introducing each of the catalyst components (a) to (d) simultaneously and independently into the reaction system, etc. Is called. Each of the above solutions is usually prepared using a reaction solvent.

(Low polymerization reaction conditions)
The ratio of each component of the catalyst used in the present embodiment is usually 1 to 50 moles, preferably 1 to 30 moles of the halogen-containing compound with respect to 1 mole of the transition metal-containing compound. Alternatively, when a nitrogen-containing compound or an aluminum-containing compound is included, the nitrogen-containing compound is 1 mol to 100 mol, preferably 1 mol to 50 mol, and the aluminum-containing compound is 1 mol to 1 mol with respect to 1 mol of the transition metal-containing compound. 200 mol, preferably 10 mol to 150 mol.

In the present embodiment, the amount of the catalyst used is not particularly limited, but it is usually 1.0 × 10 ⁻⁹ mol to 0.5 mol, preferably 5 per liter of solvent and per atom of transition metal of the transition metal-containing compound. The amount is 0.0 × 10 ⁻⁹ mol to 0.2 mol, more preferably 1.0 × 10 ⁻⁸ mol to 0.05 mol.
By using such a catalyst, for example, when ethylene is used as a raw material, hexene that is a trimer of ethylene can be obtained with a selectivity of 90% or more.

In this Embodiment, as reaction temperature, it is 0-250 degreeC normally, Preferably it is 50-200 degreeC, More preferably, it is 80-170 degreeC.
The reaction pressure is usually from normal pressure to 25 MPa, preferably from 0.5 to 15
MPa, more preferably in the range of 1.0 to 10 MPa (pressure is based on absolute pressure).

Although it does not specifically limit as a kind of reactor, A continuous stirring tank reactor, a tubular reactor, etc. are used suitably.
The residence time in the reactor is usually in the range of 1 minute to 10 hours, preferably 3 minutes to 3 hours, more preferably 5 minutes to 40 minutes.
The reaction mode of the low polymerization reaction is a continuous type. That is, an operation of supplying a raw material α-olefin to a reactor having a catalyst and withdrawing a reaction liquid containing an α-olefin low polymer produced in the reactor from the reactor is simultaneously performed. There is always a certain amount of reaction liquid in the reactor, and in the reaction liquid, in addition to the α-olefin low polymer and the solvent which are products, unreacted raw material α-olefin and by-products. High-boiling compounds including a polymer as a product and catalyst components supplied to the reactor are included.

  In the present invention, the solvent is separated from the reaction liquid continuously withdrawn from the reactor and continuously supplied to the reactor. As a method for separating the solvent, distillation is usually preferably used. The reaction liquid preferably contains a solvent, an unreacted α-olefin, a by-product having a boiling point higher than that of the target α-olefin low polymer, an α-olefin low polymer, and the like. When the solvent separated from the reaction liquid is continuously circulated and supplied to the reactor, the method for separating the by-product having a higher boiling point than the α-olefin low polymer as the target product from the reaction liquid is not particularly limited. . Usually, separation by distillation is suitably performed. When separating a by-product having a boiling point higher than that of the target product α-olefin low polymer using a distillation column, the pressure at the top of the column is usually 0.01 to 2.00 MPa on an absolute pressure basis, preferably 0.8. The theoretical plate number is usually 2 to 100, preferably 5 to 50, and the reflux ratio (R / D) is preferably 0 to 2.5, more preferably 0.1. -1.0. The lower the reflux ratio, the easier it is for the catalyst deactivator and / or the by-product having a higher boiling point than the solvent to be mixed into the solvent, and the higher the reflux ratio, the greater the amount of energy used such as steam.

  In the present invention, when the solvent separated from the reaction solution is circulated and supplied to the reactor, the concentration of the nitrogen-containing compound in the solvent needs to be 5.0 wtppm or more. The nitrogen-containing compound in the circulating solvent is contained in the reaction solution withdrawn from the reactor, and as a specific means for setting the concentration to 5.0 wtppm or more, for example, when separating the solvent The reflux ratio of the distillation column is set to 1.0 or less, and / or the position at which the reaction solution is fed to the distillation column is the bottom of the distillation column or a position within 5 theoretical plates from the bottom. Etc.

When the concentration of the nitrogen-containing compound in the circulating solvent is 5.0 wtppm or more, preferably 10.0 wtppm or more, the catalytic activity in the steady state is improved and the by-product polyethylene can be reduced.
The reason for this is not necessarily clear, but the following is presumed. That is, in a steady state in continuous operation, decomposition products such as halogen-containing compounds which are one of the catalyst components accumulate in the circulating solvent or circulating ethylene. Since this decomposition product is coordinated to the transition metal compound in the reactor, the coordination of the nitrogen-containing compound that should be coordinated to the transition metal compound is inherently inhibited, and the catalytic activity tends to decrease. Therefore, it is considered that by increasing the concentration of the nitrogen-containing compound in the circulating solvent, the nitrogen-containing compound is easily coordinated to the transition metal compound in the reactor, and the catalytic activity is not lowered. Moreover, since a nitrogen-containing compound is usually expensive, it is preferable to increase the concentration in the reactor by circulating it in the reactor together with a solvent from the viewpoint of production cost.

If the concentration of the nitrogen-containing compound in the circulating solvent is too high, it excessively coordinates to the transition metal compound and tends to reduce the catalytic activity. Therefore, the upper limit of the concentration of the nitrogen-containing compound in the circulating solvent is 200 wtppm. Preferably, 100 wtppm is more preferable.
(Production method of α-olefin low polymer)
The α-olefin low polymer in the present invention means an oligomer in which several α-olefins are bonded. Specifically, it is a polymer in which 2 to 10 α-olefins are bonded.

Next, a method for producing an α-olefin low polymer will be described using ethylene as an α-olefin and taking as an example low polymerization to 1-hexene which is a trimer of ethylene as an α-olefin low polymer.
FIG. 1 is a diagram for explaining an example of a production flow of an α-olefin low polymer in the present embodiment.

  In the example of the production flow of 1-hexene using ethylene as a raw material shown in FIG. Degassing tank 20 for separating ethylene gas, ethylene separation tower 30 for distilling off ethylene in the reaction liquid extracted from degassing tank 20, and high boiling point in the reaction liquid extracted from ethylene separation tower 30 The high boiling separation tower 40 for separating the substances (hereinafter sometimes referred to as HB (high boiler)) and the reaction liquid extracted from the top of the high boiling separation tower 40 are distilled to store 1-hexene. A hexene separation column 50 is shown. Further, a compressor 17 is provided for circulating unreacted ethylene separated in the degassing tank 20 and the condenser 16 to the reactor 10 through a circulation pipe 21.

In FIG. 1, as the reactor 10, for example, a conventionally well-known type equipped with a stirrer 10a, a baffle, a jacket and the like can be mentioned. As the stirrer 10a, a stirring blade in the form of a paddle, a fiddler, a propeller, a turbine, or the like is used in combination with a baffle such as a flat plate, a cylinder, or a hairpin coil.
As shown in FIG. 1, ethylene is continuously supplied to the reactor 10 from the ethylene supply pipe 12 a through the compressor 17 and the first supply pipe 12. Here, when the compressor 17 is, for example, a two-stage compression system, the electricity cost can be reduced by connecting the circulation pipe 31 to the first stage and connecting the circulation pipe 21 to the second stage. A solvent used for the low polymerization reaction of ethylene is supplied to the reactor 10 from the second supply pipe 13.

  On the other hand, the transition metal-containing compound and the nitrogen-containing compound prepared in advance in the catalyst tank 1c are supplied from the second supply pipe 13 to the reactor 10 through the catalyst supply pipe 13a, and the aluminum-containing compound is supplied from the third supply pipe 14. Is supplied, and the halogen-containing compound is supplied from the fourth supply pipe 15. Here, the halogen-containing compound may be supplied to the reactor 10 from the second supply pipe 13 via the supply pipe. Moreover, if the contact time with the transition metal-containing compound is also supplied to the reactor 10 within a few minutes, the aluminum-containing compound may be supplied to the reactor 10 from the second supply pipe 13 via the supply pipe. . In this method, if a static mixer or the like is installed between the second supply pipe 13 and the reactor 10, a homogeneous mixed solution of each catalyst component can be supplied to the reactor 10. Reduced.

In this Embodiment, as reaction temperature in the reactor 10, it is 0 degreeC-250 degreeC normally, Preferably it is 50 degreeC-200 degreeC, More preferably, it is 80 degreeC-170 degreeC.
Furthermore, in the trimerization reaction of ethylene, the molar ratio of 1-hexene to ethylene in the reaction solution ((molar concentration of 1-hexene in the reaction solution) / (molar concentration of ethylene in the reaction solution)) is 0.05. It is preferable to carry out so that it may become -1.5, especially 0.10-1.0. That is, in the case of continuous reaction, it is preferable to adjust the catalyst concentration, reaction pressure, and other conditions so that the molar ratio of ethylene to 1-hexene in the reaction solution falls within the above range. In the case of batch reaction, it is preferable to stop the ethylene trimerization reaction when the molar ratio is in the above range.

By performing the trimerization reaction of ethylene under such conditions, the by-product of a component having a boiling point higher than that of 1-hexene is suppressed, and the selectivity of 1-hexene tends to be further increased.
Next, the reaction solution continuously extracted from the bottom of the reactor 10 through the pipe 11 is stopped by the ethylene trimerization reaction by the quenching agent supplied from the quenching agent supply pipe 11a. It is supplied to the tank 20. In the degassing tank 20, unreacted ethylene is degassed from above and is circulated and supplied to the reactor 10 via the circulation pipe 21, the condenser 16, the compressor 17 and the first supply pipe 12. Further, the reaction liquid from which the unreacted ethylene has been degassed is extracted from the bottom of the degassing tank 20. The operating conditions of the degassing tank 20 are usually a temperature of 0 ° C. to 250 ° C., preferably 50 ° C. to 200 ° C., and the pressure is normal pressure to 15 MPa, preferably normal pressure to 9 MPa.

  Subsequently, the reaction liquid from which the unreacted ethylene has been degassed in the degassing tank 20 is extracted from the tank bottom of the degassing tank 20 and supplied to the ethylene separation tower 30 through the pipe 22. In the ethylene separation tower 30, ethylene is distilled from the top of the tower by distillation and is circulated and supplied to the reactor 10 through the circulation pipe 31 and the first supply pipe 12. Moreover, the reaction liquid from which ethylene has been removed is extracted from the bottom of the column.

The operating conditions of the ethylene separation tower 30 are usually the pressure at the top of the tower is from atmospheric pressure to 3 MPa, preferably from atmospheric pressure to 2 MPa, and the reflux ratio (R / D) is usually from 0 to 500, preferably from 0. 1-100.
Next, the reaction liquid obtained by distilling ethylene in the ethylene separation tower 30 is extracted from the bottom of the ethylene separation tower 30 and supplied to the high boiling separation tower 40 through the pipe 32. In the high boiling separation tower 40, a high boiling point component (HB: high boiler) is extracted from the bottom of the tower. Moreover, the distillate from which the high boiling point component was separated by the pipe 42 is extracted from the tower top. The operating conditions of the high boiling separation tower 40 are usually a tower top pressure of 0.01 MPa to 2.0 MPa, preferably 0.05 MPa to 1.0 MPa, and a reflux ratio (R / D) is usually 0 to 2. 0.5, preferably 0.1 to 1.0 (pressure is based on absolute pressure).

  Subsequently, the reaction liquid extracted as a distillate from the top of the high boiling separation tower 40 is supplied to the hexene separation tower 50 through the pipe 41. In the hexene separation tower 50, 1-hexene obtained by distillation is distilled out from the top of the tower through a pipe 51. Further, heptane is extracted from the bottom of the hexene separation tower 50, stored in the solvent drum 60 through the solvent circulation pipe 52, and further circulated and supplied to the reactor 10 as a reaction solvent through the second supply pipe 13. The The operating conditions of the hexene separation tower 50 are usually a tower top pressure of 0.01 MPa to 1.0 MPa, preferably 0.05 MPa to 0.5 MPa, and a reflux ratio (R / D) is usually 0 to 100, Preferably it is 0.1-20.

EXAMPLES Hereinafter, the present invention will be described more specifically with reference to examples. However, the present invention is not limited to these examples unless it exceeds the gist.
(Reference Example 1)
In FIG. 1, a complete mixing and stirring type reactor 10, a degassing tank 20, an ethylene separation tower 30, a high boiling separation tower 40, a hexene separation tower 50, and a solvent drum 60 for storing a circulating solvent are provided. In the process of connecting the other end of the solvent circulation pipe 52 connected to the bottom of the hexene separation tower 50 to the second supply pipe 13 and circulating directly to the reactor 10 without going through the solvent drum 60, the raw material α− Ethylene was used as the olefin, and 1-hexene was produced by continuous low polymerization reaction of ethylene.

From the first supply pipe 12, unreacted ethylene separated from the degassing tank 20 and the ethylene separation tower 30 is extracted together with ethylene newly supplied from the ethylene supply pipe 12 a using the pipe 31 and the pipe 21, and compressed. The machine 17 was continuously fed to the reactor 10. Further, the recovered n-heptane solvent separated in the high boiling separation column 40 and the hexene separation column 50 operated under the condition of the reflux ratio 1.1 from the second supply pipe 13 is supplied to the solvent drum 60 (0.2 MPa nitrogen seal). ) And was continuously circulated to the reactor 10 at a flow rate of 25 kg / hr. Note that. 2,5-dimethylpyrrole (b) in the n-heptane solvent circulated to the reactor is 3.9 wtppm, and is continuously fed to the reactor 10 at 0.0975 g / Hr (1.03 mmol / Hr). It was.

  From the catalyst supply pipe 13a, chromium (III) 2-ethylhexanoate (a) is converted to 0.262 mmol / Hr, and 2,5-dimethylpyrrole (b) is converted to chromium (III) 2-ethylhexanoate (a). The mixture was supplied at 3.0 equivalents and continuously supplied to the reactor 10 via the second supply pipe 13. Triethylaluminum (c) was continuously supplied from the third supply pipe 14 to the reactor 10 at 17.5 mmol / Hr. Furthermore, hexachloroethane (d) was continuously supplied from the fourth supply pipe 15 to the reactor 10 at 1.62 mmol / Hr.

Each component of these catalysts was diluted with n-heptane and supplied from a tank (not shown) sealed with nitrogen at 0.2 MPa.
The catalyst component supplied to the reactor 10 (for 2,5-dimethylpyrrole (b), also includes 2,5-dimethylpyrrole in the circulating solvent), the molar ratio of each component is (a) :( b :) (
c) :( d) = 1: 6.9: 67: 6.2 were continuously fed into the reactor 10. The reaction conditions were a reactor internal temperature of 140 ° C. and a reactor internal pressure of 7.0 MPa.

The reaction liquid continuously withdrawn from the reactor 10 was added with about 3 equivalents of 2-ethylhexanol as a catalyst deactivator with respect to triethylaluminum (c) from the deactivator supply pipe 11a. It processed in the degassing tank 20, the ethylene separation tower 30, the high boiling separation tower 40, and the hexene separation tower 50 one by one. Under the above conditions, the operation was performed in a steady state for 30 days or more.
The results are shown in Table-1. The polyethylene selectivity is calculated from polyethylene obtained by sampling the bottom liquid of the ethylene separation tower, cooling to room temperature, and drying the filtered (filter diameter 0.2 μm) residue. The C6 selectivity is obtained by analyzing the composition of each of the circulating heptane solvent and the bottom liquid of the ethylene separation tower 30 by gas chromatography (manufactured by Shimadzu Corporation, model GC-17AAF), and selecting each component generated in the reactor. The rate was calculated.
The catalyst efficiency is the product weight (unit: g) produced in one hour per chromium atomic weight (unit: g) of the catalyst component supplied in one hour.

Example 1
In Reference Example 1, the reflux ratio of the high-boiling separation tower 40 is 0.9, and 1,5-dimethylpyrrole (b) in the n-heptane solvent circulated and supplied to the reactor is supplied to the reactor 10 at 13.9 wtppm. The molar ratio of the resulting catalyst component (for 2,5-dimethylpyrrole (b), also including 2,5-dimethylpyrrole in the circulating solvent) is: (a) :( b) :( c) :( d) = 1: 17: 65: 6.0 All the same methods except that ethylene was subjected to a low polymerization reaction to produce 1-hexene. The results are shown in Table-1.

(Example 2)
In Example 1, 6.5 wtppm of 2,5-dimethylpyrrole (b) in the n-heptane solvent circulated and supplied to the reactor, chromium (III) 2 supplied from the catalyst supply pipe 13a
-The amount of ethylhexanoate (a) supplied was 0.180 mmol / Hr, and the catalyst component (2,5-dimethylpyrrole (b) supplied to the reactor 10 was 2,5-dimethylpyrrole in the circulating solvent. The low-polymerization reaction of ethylene was carried out in the same manner except that the molar ratio was (a) :( b) :( c) :( d) = 1: 12: 73: 4.5. 1-hexene was produced. The results are shown in Table-1.

(Example 3)
In Example 1, the reflux ratio of the high-boiling separation column 40 is 0.6, 2,5-dimethylpyrrole (b) in the n-heptane solvent circulated to the reactor is 10.4 wtppm, from the catalyst supply pipe 13a. The amount of chromium (III) 2-ethylhexanoate (a) supplied is 0.18.
1 mmol / Hr, catalyst component supplied to the reactor 10 (2,5-dimethylpyrrole (b)
Is the molar ratio of 2,5-dimethylpyrrole in the circulating solvent) (a) :( b
) :( c) :( d) = 1: 18: 72: 4.4 The ethylene was subjected to a low polymerization reaction in the same manner to produce 1-hexene. The results are shown in Table-1.

Example 4
In Example 1, the reflux ratio of the high-boiling separation tower 40 is 0.3, 2,5-dimethylpyrrole (b) in the n-heptane solvent circulated and supplied to the reactor is 13.7 wtppm, from the catalyst supply pipe 13a. The amount of chromium (III) 2-ethylhexanoate (a) supplied is 0.17.
6 mmol / Hr, catalyst component supplied to the reactor 10 (2,5-dimethylpyrrole (b)
Is the molar ratio of 2,5-dimethylpyrrole in the circulating solvent) (a) :( b
) :( c) :( d) = 1: 24: 74: 4.6 All the same methods except that ethylene was subjected to a low polymerization reaction to produce 1-hexene. The results are shown in Table-1.

(Example 5)
In Example 1, the reflux ratio of the high boiling point separation column 40 is 0.3, 2,5-dimethylpyrrole (b) in the n-heptane solvent circulated to the reactor is 15.5 wtppm, from the catalyst supply pipe 13a. The amount of chromium (III) 2-ethylhexanoate (a) supplied is 0.16.
8 mmol / Hr, catalyst component supplied to the reactor 10 (2,5-dimethylpyrrole (b)
Is the molar ratio of 2,5-dimethylpyrrole in the circulating solvent) (a) :( b
) :( c) :( d) = 1: 27: 78: 4.7 All except that the low polymerization reaction of ethylene was carried out in the same manner to produce 1-hexene. The results are shown in Table-1.

  From the results shown in Table 1, it can be seen that the higher the concentration of recovered 2,5-dimethylpyrrole in recovered heptane, the higher the catalyst efficiency and the lower the polyethylene selectivity.

1c: catalyst tank,
10 ... reactor,
10a: stirrer,
11, 22, 32, 41, 42, 51 ... piping,
11a ... Deactivating agent supply pipe 12 ... First supply pipe,
12a ... ethylene supply piping,
13 ... second supply pipe,
13a ... catalyst supply piping,
14 ... Third supply piping,
15 ... Fourth supply pipe,
21, 31 ... circulation piping,
16 ... Condenser,
17 ... Compressor,
20 ... degassing tank,
30 ... ethylene separation tower,
40 ... high boiling separation tower,
50 ... hexene separation tower,
52. Solvent circulation piping,
60 ... solvent drum

Claims (8)

  Using a catalyst formed from a transition metal-containing compound, a nitrogen-containing compound and an aluminum-containing compound, the raw material α-olefin is continuously supplied to the reactor, and the raw material α-olefin is supplied in the reactor in the presence of a solvent. An α-olefin low polymer is produced by a low polymerization reaction, a reaction liquid containing the α-olefin low polymer is continuously withdrawn from the reactor, a solvent is separated from the reaction liquid, and the separated solvent is removed from the reaction liquid. A process for producing an α-olefin low polymer in which the concentration of a nitrogen-containing compound in a solvent to be circulated in a steady state is 5.0 wtppm or more when continuously circulated to a reactor.   When separating a by-product having a boiling point higher than that of the target product α-olefin low polymer from the reaction solution, distillation is performed using a distillation column, and the reflux ratio is 1.0 or less. The method for producing an α-olefin low polymer according to claim 1.   The method for producing an α-olefin low polymer according to claim 1, wherein the nitrogen-containing compound is a pyrrole-containing compound.   The method for producing an α-olefin low polymer according to any one of claims 1 to 3, wherein the transition metal-containing compound contains a transition metal of Groups 4 to 6 in the periodic table.   5. The α according to claim 1, wherein the transition metal-containing compound contains one or more metals selected from the group consisting of chromium, titanium, zirconium, vanadium, and hafnium. -Manufacturing method of olefin low polymer.   The method for producing an α-olefin low polymer according to any one of claims 1 to 5, wherein the catalyst further contains a halogen-containing compound.   The manufacturing method of the alpha-olefin low polymer of any one of Claims 1-6 whose said solvent is a saturated hydrocarbon. The method for producing an α-olefin low polymer according to any one of claims 1 to 7, wherein the α-olefin is ethylene and the α-olefin low polymer is 1-hexene.

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