JP2002255864A - Method for manufacturing ethylene oligomer - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a method capable of affording an ethylene oligomer which is free from impurities and has a higher purity, in the manufacturing of an ethylene oligomer by using a Ziegler catalyst and recycling the reaction solvent. SOLUTION: The method for manufacturing an ethylene oligomer is carried out as follows: the polymerization reaction of ethylene is carried out in the presence of a Ziegler catalyst in an organic solvent; the obtained polymerization reaction product is subjected to distillation to separate the organic solvent; and the recovered solvent is recycled to the polymerization reaction. The concentration of >=3C olefins contained in the organic solvent to be recycled to the polymerization reaction is <=2 wt.%.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for producing an ethylene low polymer having an unsaturated double bond and having 4 to 24 carbon atoms, and more particularly, to a raw material such as a polymer, a plasticizer or a surfactant. The present invention relates to a method for producing an ethylene low polymer with higher purity and high quality when producing an ethylene low polymer useful as a polymer.

[0002]

2. Description of the Related Art Linear ethylene low polymers having an unsaturated double bond at the α-position having 4 to 24 carbon atoms are used as monomers of olefin polymers, comonomers of various high molecular polymers, It is a useful substance that is widely used as a raw material for plasticizers and surfactants. This ethylene low polymer is usually produced by polymerizing ethylene as a raw material using a Ziegler catalyst, and this production process generally includes a polymerization reaction system, an unreacted ethylene recovery system,
It comprises a catalyst deactivation and deashing system, a reaction solvent and a fractional distillation system of the target ethylene low polymer (for example, see JP-A-3-220135).

[0003]

However, in the method comprising such a production process, when the organic solvent finally obtained in the fractionation system is recycled to the polymerization reaction system for the purpose of reuse, the organic solvent is not recycled. A considerable amount of the produced ethylene low-polymer olefin is mixed in the organic solvent. In addition, generally, the ethylene low polymer produced by the above method contains impurities such as paraffin, internal olefin, and branched olefin, and these impurities cause a remarkable deterioration in quality of the final product such as polyethylene resin. Become. In particular, it has been found that when an organic solvent is recycled to a polymerization reaction system and used as a reaction solvent, the above undesirable results are remarkable due to the presence of an olefin other than ethylene in the organic solvent. Further, although the catalyst is prepared in a solvent, there is a possibility that the catalytic activity is reduced due to the presence of the olefin, or the catalyst feed line is clogged due to the polymerization of the olefin. That is, the present invention has been made in view of the above problems,
An object of the present invention is to provide a method capable of obtaining a higher-purity ethylene low polymer containing no impurities in the production of an ethylene low polymer using a Ziegler-based catalyst and recycling and using a reaction solvent.

[0004]

Means for Solving the Problems The inventors of the present invention have conducted intensive studies in view of the above problems, and as a result, have found that olefins other than ethylene present in the reaction system, particularly the reaction solvent, especially the reaction used for recycling. It has been found that the above object of the present invention can be achieved by reducing the amount of the olefin component introduced into the reaction system from the solvent. The present invention has been completed based on such findings. That is, the present invention performs a polymerization reaction of ethylene in an organic solvent in the presence of a Ziegler-based catalyst, and circulates and uses the organic solvent separated by distilling the obtained polymerization reaction product in the polymerization reaction. A method for producing an ethylene low polymer, comprising: reducing the concentration of an olefin having 3 or more carbon atoms in an organic solvent circulating in the polymerization reaction system, particularly the organic solvent circulating in the polymerization reaction system, to 2% by weight or less. It is intended to provide a manufacturing method.

[0005]

BEST MODE FOR CARRYING OUT THE INVENTION Hereinafter, the present invention will be described in more detail. In the present invention, the ethylene low polymer is obtained by polymerizing ethylene in the presence of a Ziegler catalyst. The Ziegler-based catalyst comprises a combination of (A) a transition metal compound, (B) an organoaluminum, and (C) a third component used as desired.
As the transition metal compound, a general formula: MX _x Y _y O _z (I) wherein M is a zirconium atom or a titanium atom, X is a halogen atom (a chlorine atom, a bromine atom or an iodine atom), and Y is RO- _{, R 2 N -, - OCOR} , -OSO 3
R, R-, -Cp (cyclopentadienyl) (provided that R,
R ′ and R ″ are a linear or branched alkyl group having 1 to 20 carbon atoms) or β-diketonate represented by the formula (II).

[0006]

Embedded image

(Wherein R ¹ , R ² and R ³
Are each independently a hydrogen atom, a C 1-20 alkyl group or a C 1-20 substituted with a halogen atom.
And ^one of R ¹ , R ² and R ³ is an alkyl group having 1 to 20 carbon atoms substituted with a halogen atom. ) Also, x, y, and z are integers from 0 to 4, and x
+ Y + z = 4. ] Is used. Specific examples of such compounds include:

[0008] ZrCl_Four, ZrBr_Four, ZrI_Four, Zr
BrCl_Three, ZrBr_TwoCl_Two, TiCl_Four, TiBr
_Four, TiI_Four, TiBrCl_Three, TiBr_TwoCl_Two, Z
r (OC_TwoH_Five)_Four, Zr (OC_TwoH_Five)_TwoCl_Two, Z
r (On-C_ThreeH₇)_Four, Zr (On-C_ThreeH₇)
_TwoCl_Two, Zr (O-iso-C_ThreeH₇)_Four, Zr (O
-Iso-C_ThreeH₇)_TwoCl_Two, Zr (On-C_FourH
₉)_Four, Zr (On-C_FourH₉)_TwoCl_Two, Zr (O
-Iso-C_FourH₉)_Four, Zr (O-iso-C
_FourH₉)_TwoCl_Two, Zr (O-tert-C
_FourH₉)_Four, Zr (O-tert-C_FourH₉)_TwoC
l_Two, Zr ((CH_Three)_TwoN)_Four, Zr ((C_TwoH_Five)
_TwoN)_Four, Zr ((n−C_ThreeH₇)_TwoN)_Four, Zr
((Iso-C_ThreeH₇)_TwoN)_Four, Zr ((n−C_FourH
₉)_TwoN)_Four, Zr ((tert-C_FourH₉)
_TwoN)_Four, Zr (OSO_ThreeCH_Three)_Four, Zr (OSO_Three
C_TwoH_Five)_Four, Zr (OSO_ThreeC_ThreeH₇)_Four, Zr (O
SO_ThreeC_FourH₉)_Four, ZrCp_TwoCl_Two, ZrCp_TwoC
lBr, Ti (OC_TwoH_Five)_Four, Ti (OC_TwoH_Five)_Two
Cl_Two, Ti (On-C_ThreeH₇)_Four, Ti (On-
C_ThreeH₇)_TwoCl_Two, Ti (O-iso-C
_ThreeH₇)_Four, Ti (O-iso-C_ThreeH₇)_TwoCl_Two,
Ti (On-C_FourH₉)_Four, Ti (On-C
_FourH₉)_TwoCl_Two, Ti (O-iso-C_FourH₉)_Four,
Ti (O-iso-C_FourH₉)_TwoCl_Two, Ti (Ot
ert-C_FourH₉)_Four, Ti (O-tert-C
_FourH₉)_TwoCl_Two, Ti ((CH_Three)_TwoN)_Four, Ti
((C_TwoH_Five) _TwoN)_Four, Ti ((n-C_ThreeH₇)
_TwoN)_Four, Ti ((iso-C_ThreeH₇)_TwoN)_Four, Ti
((N-C_FourH₉)_TwoN)_Four, Ti ((tert-C_Four
H₉)_TwoN) _Four, Ti (OSO_ThreeCH_Three)_Four, Ti (O
SO_ThreeC_TwoH_Five)_Four, Ti (OSO_ThreeC_ThreeH₇)_Four, T
i (OSO_ThreeC_FourH₉)_Four, TiCp_TwoCl_Two, TiC
p_TwoClBr, Zr (OCOC_TwoH_Five)_Four, Zr (OC
OC_TwoH_Five)_TwoCl_Two, Zr (OCOC_ThreeH₇)_Four, Z
r (OCOC_ThreeH₇)_TwoCl_Two, Zr (OCOC
_ThreeH₇)_Four, Zr (OCOC_ThreeH₇)_TwoCl_Two, Zr
(OCOC_FourH₉)_Four, Zr (OCOC_FourH₉)_TwoCl
_Two, Ti (OCOC_TwoH_Five)_Four, Ti (OCOC
_TwoH_Five) _TwoCl_Two, Ti (OCOC_ThreeH₇)_Four, Ti
(OCOC_ThreeH₇)_TwoCl_Two, Ti (OCOC_ThreeH₇)
_Four, Ti (OCOC_ThreeH₇)_TwoCl_Two, Ti (OCOC
_FourH ₉)_Four, Ti (OCOC_FourH₉)_TwoCl_Two, ZrC
l_Two(HCOCFCOF)_Two, ZrCl_Two(CH_ThreeCO
CFCOCH_Three)_TwoAnd the like.

- 0009] As the (B) an organoaluminum the general formula _{AlY a X b O c N d} (III) [wherein, X is halogen atom (chlorine atom, bromine atom or iodine atom), Y is RO-, R ₂ N-, -OCO
R and R- (where R is a linear or branched alkyl group having 1 to 20 carbon atoms, a, b, c, and d are integers of 0 to 3,
a + b + c + d = 3. )] And / or a compound represented by the general formula Al ₂ Ya _{′ Xb ′} O _{c ′} N _{d ′} (IV). [In the formula, X is a halogen atom (a chlorine atom, a bromine atom or an iodine atom), and Y is RO-, R ₂ N-, -OCOR, -RCOC.
R'COR "and R- (where R, R 'and R" are linear or branched alkyl groups having 1 to 20 carbon atoms, a',
b ′, c ′ and d ′ are integers from 0 to 6, and a ′ + b ′ + c ′
+ D '= 6. )]

The compound represented by the above general formula (III) is
For example, for example, Al (CH_Three)_Three, Al (C
_TwoH_Five)_Three, Al (C_ThreeH₇)_Three, Al (iso-C_Three
H₇)_Three, Al (C_FourH₉)_Three, Al (iso-C_FourH
₉)_Three, Al (C_FiveH₁₁)_Three, Al (C₆H₁₃)_Three, A
l (C₈H₁₇)_Three, Al (C_TwoH_Five)_TwoCl, Al (C
_TwoH_Five)_TwoBr, Al (C_TwoH_Five)_TwoI, Al (C_TwoH
_Five) Cl_Two, Al (C_TwoH_Five) Br_Two, Al (C
_TwoH_Five) I_Two, AlC_TwoH_Five(OC_TwoH_Five) _Two, AlC
_TwoH_Five(OC_ThreeH₇)_Two, AlC_TwoH_Five(OC_FourH₉)
_Two, Al (OC_TwoH_Five)_TwoCl, Al (OC_ThreeH₇)_Two
Cl, Al (OC_FourH₉)_TwoCl, Al (OC_TwoH_Five)
Cl_Two, Al (OC_ThreeH₇) Cl_Two, Al (OC
_FourH₉) Cl _Two, AlC_TwoH_Five(OCOC_TwoH_Five)_Two,
AlC_TwoH_Five(OCOC_ThreeH₇)_Two, AlC_TwoH_Five(O
COC_FourH₉)_Two, Al (OCOC_TwoH_Five)_TwoCl, A
l (OCOC_ThreeH₇)_TwoCl, Al (OCOC_FourH₉)
_TwoCl, Al (OCOC_TwoH_Five) Cl_Two, Al (OCO
C_ThreeH₇) Cl_Two, Al (OCOC_FourH₉) Cl_Two, A
l (C_TwoH_Five)_TwoOC_TwoH_Five, Al (C_TwoH_Five)_TwoOC
_ThreeH₇, Al (C_TwoH_Five)_TwoOC_FourH₉, Al (C_TwoH
_Five)_TwoN (C_TwoH_Five)_Two, Al (C_TwoH_Five)_TwoN (C_Three
H₇)_Two, Al (C_TwoH_Five)_TwoN (C_FourH₉)_Twoetc
Examples of the compound represented by the general formula (IV)
Is, for example,

Al_Two(CH_Three) Cl_Three, Al_Two(C
H_Three)_ThreeBr_Three, Al_Two(C_TwoH_Five)_ThreeCl_Three, Al_Two
(C_TwoH_Five)_ThreeBr_Three, Al_Two(C_TwoH_Five)_ThreeI_Three, A
l_Two(C_TwoH_Five)_TwoBrCl_Two, Al_Two(C_ThreeH₇)_Three
Cl_Three, Al_Two(Iso-C_ThreeH₇)_ThreeCl_Three, Al_Two
(C_FourH₉)_ThreeCl_Three, Al_Two(Iso-C_FourH₉)_Three
Cl _Three, Al_Two(C_FiveH₁₁)_ThreeCl_Three, Al_Two(C₈H
₁₇)_ThreeCl_Three, Al_Two(C_TwoH_Five)_Two(CH_Three) C
l_Three, Al_Two(OC_TwoH_Five)_ThreeCl_Three, Al_Two(OC_Three
H ₇)_ThreeCl_Three, Al_Two(OC_FourH₉)_ThreeCl_Three, Al
_Two(OCOC_TwoH_Five)_ThreeCl_Three, Al_Two(OCOC_ThreeH
₇)_ThreeCl_Three, Al_Two(OCOC_FourH₉)_ThreeCl_ThreeSuch
Is mentioned.

Further, as the third component (C) used if desired, at least one compound selected from a sulfur compound, a phosphorus compound and a nitrogen compound can be used. This third component contributes to the improvement of the purity of the ethylene low polymer as a product. The sulfur compound is not particularly limited as long as it is an organic sulfur compound. For example, thioethers such as dimethyl sulfide, diethyl sulfide, dipropyl sulfide, dihexyl sulfide, dicyclohexyl sulfide, and diphenylthioether: dimethyl disulfide, diethyl disulfide Dialkyl disulfide compounds such as dipropyl disulfide, dibutyl disulfide, dihexyl disulfide, dicyclohexyl disulfide, and ethyl methyl disulfide; thiophene, 2-methylthiophene, 3-methylthiophene,
Thiophenes such as 2,3-dimethylthiophene, 2-ethylthiophene and benzothiophene, and heterocyclic sulfur compounds such as tetrahydrothiophene and thiopyran; aromatics such as diphenyl sulfur, diphenyl disulfide, methylphenyl disulfide and methylphenyl sulfur Sulfur compounds:
Thiourea; sulfides such as methyl sulfide, ethyl sulfide and butyl sulfide are preferably used.

The phosphorus compound is not particularly limited as long as it is an organic phosphorus compound, and examples thereof include phosphines such as triphenylphosphine, triethylphosphine, tributylphosphine, tripropylphosphine, trioctylosphin, and tricyclohexylphosphine. It is preferably used. The nitrogen compound is not particularly limited as long as it is an organic nitrogen compound, and examples thereof include methylamine, ethylamine, propylamine, butylamine, pentylaine, hexylamine, cyclohexylamine, octylamine, decylamine, aniline, and benzyl. Amine, naphthylamine, dimethylamine, diethylamine, dibutylamine, diphenylamine, methylphenylamine, trimethylamine, triethylamine, tributylamine, triphenylamine,
Organic amines such as pyridine and picoline are preferably used.

In the present invention, among the various sulfur compounds, phosphorus compounds and nitrogen compounds, for example, dimethyl disulfide, thiophene, thiourea, triphenylphosphine, tributylphosphine, trioctylphosphine,
One or more compounds selected from aniline and the like can be suitably used. This polymerization reaction of ethylene is usually performed in an organic solvent. Examples of the organic solvent include alicyclic compounds such as cyclohexane and decalin, aromatic hydrocarbons such as benzene, toluene, xylene, chlorobenzene, ethylbenzene, dichlorobenzene and chlorotoluene and halogen compounds thereof, pentane, hexane, and the like. Aliphatic hydrocarbons such as heptane, octane, nonane and decane, dichloroethane,
An aliphatic hydrocarbon halide such as dichlorobutane can be used.

In the present invention, the component (A) and the component (B)
The mixing ratio of the component, the component (C) and the above-mentioned organic solvent is usually 0.5% of the component (A) per 250 ml of the organic solvent.
01-5 mmol, preferably 0.03-1 mmol,
Component (B) is usually added in an amount of 0.05 to 15 mmol, preferably
0.06 to 3 mmol, component (C) is usually 0.05 to 20
Mmol, preferably 0.1 to 10 mmol when the sulfur compound is used as the component (C), and 0.05 to 5 mmol when the nitrogen compound or the phosphorus compound is used as the component (C). . In addition, (A)
Regarding the mixing ratio of the component and the component (B), a more preferable result can be obtained by setting Al / Zr or Ti (molar ratio) in a range of 1 to 15.

The polymerization reaction of ethylene in the present invention is usually carried out at a temperature of 100 to 150 ° C. and 30 to 90 kg / cm ^2.
The test is performed under a pressure of G (2.94 to 8.82 MPa). The reaction time depends on the temperature and the pressure and cannot be determined uniformly, but usually about 10 to 60 minutes is sufficient. In the production method of the present invention, ethylene is used as a raw material, and the obtained ethylene low polymer is a linear low polymer having an unsaturated double bond in the α-position having 4 to 24 carbon atoms, particularly 4 to 18 carbon atoms. A polymer, specifically, 1-butene,
1-hexene, 1-octene, 1-decene, 1-dodecene, 1-tetradecene, 1-hexadecene, 1-octadecene, etc., and this ethylene lower polymer is formed as a mixture thereof.

In the present invention, the reaction product liquid obtained by polymerizing ethylene is subsequently subjected to recovery of unreacted ethylene, deactivation of the catalyst, and demineralization. Here, it is necessary to maintain the temperature of the reaction product liquid after the completion of the polymerization reaction at 90 ° C. or higher. The temperature is not particularly limited as long as it is 90 ° C. or higher, but is usually 90 to 150 ° C., preferably 100 to 130 ° C. If the temperature is too high, the purity of the product may decrease, which is not preferable. The amount of the polymer by-produced by the polymerization reaction is not uniform depending on the reaction conditions, but it is usually 300 to 500 ppm, and the type of the organic solvent used for the polymerization reaction is dissolved by maintaining the reaction product liquid at 90 ° C. or higher. Regardless, stable operation can be continued.

Next, in the present invention, the processing system is
The catalyst is deactivated by introducing a deactivator at a pressure of about / cm ² · G (0.39 MPa). At this time, examples of the deactivator used include basic nitrogen compounds, water, alcohols, carboxylic acids, and phenols. Among these, examples of the basic nitrogen compounds include ammonia or methylamine, ethylamine, propylamine, Butylamine, pentylamine, hexylamine, cyclohexylamine, octylamine, decylamine, aniline, benzylamine, naphthylamine, dimethylamine, diethylamine, dibutylamine, diphenylamine, methylaphenylamine, trimethylamine, triethylamine, tributylamine, triphenylamine, pyridine And amines such as picoline.

After the deactivation treatment, a deashing treatment is performed, and an organic solvent and unreacted ethylene are separated and recovered by distillation. The recovered unreacted ethylene and organic solvent are recycled to the polymerization reaction system. The ethylene low polymer which is the target product in the present invention can be obtained as desired various ethylene low polymer mixed products by a multistage distillation treatment. By appropriately selecting the reaction conditions, a larger amount of an ethylene low polymer having a desired number of carbon atoms can be obtained from this mixed product.

In the present invention, by the above-mentioned distillation step,
Recycle the separated and recovered organic solvent to the polymerization reaction system,
The solvent is used as a reaction solvent. At that time, the concentration of the olefin having 3 or more carbon atoms, for example, the olefin having 4 or 8 carbon atoms in the solvent must be 2% by weight or less.
If the concentration exceeds 2% by weight, impurities in the produced ethylene low polymer will increase, resulting in deterioration of the quality of the final product such as polyethylene resin. For this reason, in the present invention, the olefin concentration in the organic solvent to be recycled is preferably 1% by weight or less, more preferably
0.5% by weight or less.

In the present invention, it is preferable to carry out distillation by the following method so that the concentration of the olefin having 3 or more carbon atoms in the separated and recovered organic solvent is 2% by weight or less.
It is preferable that the distillation apparatus be composed of two or more distillation columns. As a flow of the distillation apparatus, for example, when a solvent is separated and recovered in two distillation columns, an olefin and water lighter than the solvent are separated from the top in the first distillation column, and the bottom liquid is introduced into the second distillation column. It is possible to recover the solvent from the top of the second distillation column. In this case, the number of theoretical plates in each distillation column is preferably 30 or more, and the reflux ratio is preferably 4 or more. In the present invention, the water concentration in the organic solvent circulated through the polymerization reaction system is more preferably 8 ppm by weight or less. When the water concentration exceeds 8 ppm by weight, the activity of the catalyst used is reduced, and high activity cannot be maintained. For this reason, in the present invention, the water concentration in the solvent to be recycled is preferably set to 5 ppm by weight or less.

Next, preferred embodiments of the present invention will be described with reference to the accompanying drawings. FIG. 1 is an example of a process chart for carrying out the present invention, in which a reaction product liquid containing a Ziegler catalyst, a solvent, unreacted ethylene and an ethylene low polymer obtained in a reactor 1 is Is supplied to the first-stage flash tank 3 via the control valve 2 and further to the second-stage flash tank 6 via the control valve 5. Note that the product liquid after the first-stage flash is heated by the heat exchanger 4 before being supplied to the second-stage flash tank in order to maintain the temperature at or above a predetermined temperature. In these flash tanks, unreacted ethylene dissolved in the reaction product liquid is recovered. Next, this reaction product liquid is sent to the deactivator 8, where the catalyst is deactivated by the deactivator 13. Light α-olefin slightly entrained in the recovered ethylene is recovered in the pot 10 and sent to the deactivator 8. Next, it is sent to the demineralizer 9, washed with the washing water 14, and then separated.
Sent to The oil tank and the water tank are separated in the separation tank 15, and the water tank is discarded outside the system as drainage 16, and the oil tank is sent to a dissolving tank 19 provided with a heat exchanger 17 and a pump 18, heated, and After the polymer therein is completely dissolved again, it is sent to the distillation system, and the solvent and the ethylene lower polymer are fractionated. In the present invention, the concentration of the olefin having 3 or more carbon atoms in the separated and recovered organic solvent is set to 2% by weight or less, and distillation using a plurality of distillation columns is used to separate each ethylene low polymer. Is preferred. Although various flows of the distillation system can be cited, two methods shown in FIGS. 3 and 4 can be mentioned as examples.

Distillation flow example 1 (FIG. 3) The liquid after the demineralization treatment is introduced into the first distillation column 30, and from the top of the column, a liquid mainly composed of α-olefin which is an ethylene low polymer of C6 or less. Is removed from the bottom of the column to obtain a liquid mainly composed of an α-olefin, which is a C8 or higher ethylene low polymer, and an organic solvent. The top liquid of the first distillation column 30 is introduced into the second distillation column 31, and offgas and water are withdrawn from the top of the column.
The α-olefin of C4 or more obtained from the bottom of the column is introduced into the third distillation column 32, and the α-olefin of C4 from the top and the α-olefin of C6 from the bottom are obtained.
An olefin is obtained. The bottom liquid of the first distillation column 30 is introduced into the fourth distillation column 33 to obtain an organic solvent from the top, and a liquid mainly composed of α-olefin which is an ethylene low polymer of C8 or more is obtained as the bottom liquid. Can be In the present invention, the organic solvent obtained here is recycled to the polymerization reaction system as a reaction solvent again. The bottom liquid of the fourth distillation column 33 is supplied to the distillation columns 34, 35, 36, 37, 38, 39 in the same manner as described above.
And C8, C10, C12, C1 from the top
4. An α-olefin which is an ethylene low polymer of C16 and C18 is obtained, and a liquid mainly composed of an α-olefin which is an ethylene low polymer of C20 or more is obtained from the bottom of the final distillation column 39. .

Distillation flow example 2 (FIG. 4) The liquid after the demineralization treatment is introduced into the first distillation column 40, and from the top of the column, an α-olefin, which is a C8 or lower ethylene low polymer, and an organic solvent are the main components. Is withdrawn, and C1 is discharged from the bottom of the tower.
A liquid containing as a main component an α-olefin as an ethylene low polymer of 0 or more is obtained. The top liquid is introduced into the second distillation column 41, off-gas and water are withdrawn from the top of the column, and the α-olefin of C4 or more and the organic solvent obtained from the bottom are converted into the third distillation column 42, the fourth distillation column 43, and sequentially introduced into the fifth distillation column 44, C6 and an organic solvent are obtained from the top of the column, and C8 is obtained as a bottom liquid of the 44 column. In the present invention, the obtained organic solvent is recycled to the polymerization reaction system again as a reaction solvent. The bottom liquid obtained from the distillation column 40 is introduced into the distillation columns 45, 46, 47, 48 and 49 sequentially in the same manner as described above, and the ethylene low polymer of C10, C12, C14, C16 and C18 is introduced from the top of the column. A certain α-olefin is obtained, and from the bottom of the final distillation column 49, a liquid mainly containing α-olefin which is an ethylene low polymer of C20 or more is obtained.

[0025]

EXAMPLES The present invention will be described in more detail with reference to the following examples, which should not be construed as limiting the invention thereto. Example 1 [Preparation of catalyst] In a 500-mL flask equipped with a stirrer, 25 mmol of anhydrous zirconium tetrachloride and 250 mL of dried cyclohexane were introduced under an argon atmosphere, followed by stirring at room temperature for 10 minutes. To this was added triethylaluminum _{[(C 2 H 5) 3} Al], followed by the addition of ethylaluminum sesquichloride _{[(C 2 H 5) 3} Al 2 Cl 3]. The amount of triethyl aluminum and ethyl aluminum sesquichloride _{are, (C 2 H 5) 3} Al 2 Cl 3 / (C 2 H 5) 3 Al = 3.
5 (molar ratio), [(C ₂ H ₅ ) ₃ Al ₂ Cl ₃ + (C ₂ H ₅ ) ₃ Al] / ZrCl
₄ = 7 (molar ratio). After all the addition was completed, the mixture was heated and stirred at 70 ° C. for 2 hours under an argon atmosphere to form a complex, thereby preparing a catalyst solution.

[Polymerization reaction] The reaction was carried out continuously using a complete mixing tank type (1 liter internal volume) reactor. The catalyst solution is prepared by mixing the catalyst solution with cyclohexane dried under an argon atmosphere, adjusting the concentration of zirconium tetrachloride to 0.08 mmol / l-cyclohexane, and further increasing the thiophene to 3 times the molar amount of zirconium tetrachloride. A constant amount (700 cc / hour) was supplied to the reactor. The reactor level was 500 cc and the residence time was about 43 minutes on a solvent basis. The reaction is 120 ° C, 65kg / cm ² · G
(6.4 MPa), and the stirring rotation speed was 500 rpm.
The reaction pressure of high-purity ethylene gas was 65 kg / cm ²
It was fed continuously to maintain G. Table 1 shows the conditions and results.

[0027]

[Table 1]

[Catalyst deactivation treatment] The reaction solution obtained in the above polymerization reaction was subjected to cyclohexane 546 g / hour.
(700 cc / hr), 225 g / hr of ethylene low polymer, and a total amount of 771 g / hr, were continuously supplied to the deactivation tank to deactivate the catalyst. The deactivator was supplied at a rate of 28 g / hour using 10% by weight aqueous ammonia. The deactivation tank was set at a pressure of 4 kg / cm ² · G (0.39 MPa), at a temperature of 100 ° C., and stirred at 700 rpm. This operation was performed using the apparatus shown in FIG. The product liquid after the deactivation treatment was filtered to remove the wax content with filter paper. The filtrate was washed twice with twice the volume of ion-exchanged water, and then dried over anhydrous potassium carbonate. The colorless and transparent reaction product liquid thus obtained was analyzed by gas chromatography to determine the distribution and purity of the product ethylene low polymer. The product distribution was determined by Schultz.
It was calculated from the Flory distribution.

[Distillation operation] The polymerization reaction solution after deactivation of the catalyst obtained as described above was separated by distillation in the following manner to recover cyclohexane. The polymerization reaction solution was introduced at a flow rate of 360 g / hour into an Oldershaw distillation apparatus (first distillation column) having an inner diameter of 40 mmφ. The theoretical number of plates in the first distillation column is approximately 15 in the enrichment section and 15 in the recovery section. The pressure at the top was normal pressure, and the operation was carried out at a top temperature of 66.1 ° C., a bottom temperature of 90.7 ° C., and a reflux ratio of 5. From the top of the column, a liquid mainly composed of an ethylene low polymer of C6 or less and cyclohexane is withdrawn at a flow rate of 47 g / hour, and most of the cyclohexane and C8 are discharged from the bottom of the column.
The liquid containing the above ethylene low polymer as a main component is 313 g /
Obtained at flow rates over time.

The bottom liquid from the first distillation column was introduced into another Oldershaw distillation apparatus (second distillation column) having an inner diameter of 40 mmφ. The number of theoretical plates in the second distillation column is also approximately 15
There are 15 stages and 15 stages of the collecting unit. The top pressure was normal pressure, the operation was carried out at a top temperature of 80.0 ° C., a bottom temperature of 170.9 ° C., and a reflux ratio of 5. From the top of the column, a liquid containing cyclohexane as a main component
The liquid was extracted at a flow rate of 0 g / hour, and a liquid containing cyclohexane and an ethylene low polymer of C8 or more as main components was obtained at a flow rate of 143 g / hour from the bottom of the column. Table 2 shows the composition of the liquid obtained from the top of the second distillation column. The olefin concentration above C3 was 0.33% by weight. This distillation operation was performed using the apparatus shown in FIG. Next, a polymerization reaction was carried out in the same manner as described above except that the liquid containing cyclohexane as a main component obtained from the top of the second distillation column by the above method was used as a reaction solvent. As a result, catalyst activity and product distribution were equivalent to those shown in Table 1. Table 3 shows the C18 purity. In addition, C18 purity is the production ratio of 1-octadecene, which is the target product, in the total production amount of C18.

Examples 2 and 3 and Comparative Example 1 Examples 2 and 3 and Comparative Example 1 were carried out in the same manner as in Example 1 except that the distillation conditions were changed as shown in Table 4.
In each case, the catalyst activity and product distribution were equivalent to those shown in Table 1. Table 2 shows the composition of the liquid obtained from the top of the second distillation column. Table 3 shows the C18 purity when a polymerization reaction was carried out using a liquid containing cyclohexane as a main component obtained from the top of the second distillation column as a reaction solvent.

[0032]

[Table 2]

[0033]

[Table 3]

[0034]

[Table 4]

[0035]

According to the present invention, in the production of an ethylene low polymer using a Ziegler catalyst and recycling the reaction solvent, a higher purity ethylene low polymer containing no impurities can be obtained. .

[Brief description of the drawings]

FIG. 1 is a schematic process diagram showing a process for carrying out the present invention.

FIG. 2 is a schematic process diagram showing a step of performing a catalyst deactivation treatment in the method of the present invention.

FIG. 3 is a schematic process chart showing an example of a step of performing distillation in the method of the present invention.

FIG. 4 is a schematic process chart showing an example of a step of performing distillation in the method of the present invention.

FIG. 5 is a schematic process diagram showing a process of performing distillation in an example of the present invention.

[Explanation of symbols] 1: Reactor 3, 6: Flash tank 4, 7, 11, 18, 27, 28, 50, 55, 60:
Pump 8: deactivator 9: demineralizer 10, 24, 61: pot 17: heat exchanger 19: dissolution tank 25: deactivation tank 26: ammonia water tank 30-49: distillation column 51: first distillation column 52, 57: Condenser 53, 58: Receiver 54, 59: Oil bath 56: Second distillation column

──────────────────────────────────────────────────続 き Continued on the front page (51) Int.Cl. ⁷ Identification symbol FI Theme coat ゛ (Reference) C08F 10/02 C08F 10/02 // C07B 61/00 300 C07B 61/00 300 F term (Reference) 4H006 AA02 AC21 AC29 BA09 BA10 BA36 BA37 BA41 BA44 BB12 BB41 BC14 BC35 BC37 BD35 BD52 BD60 BD81 BD84 4H039 CA21 CL19 4J011 AA01 AA05 AC01 DA04 DB27 DB28 DB30 DB32 HB22 4J028 AA01A AB00A AB01A AC02A AC04A AC09AACACA AC05A ACACA AC05A BB01B BC14B BC15B BC16B BC17B BC18B BC20B BC24B BC28B EA01 EB02 EC01 FA02 GA02 4J128 AA01 AB00 AB01 AC02 AC04 AC05 AC06 AC07 AC08 AC09 AC22 AC24 AC25 AC26 AC27 AE00 BA00A BA01B BB00A BB01 BC16B02BC18BBC BC

Claims (5)

[Claims] 1. A polymerization reaction of ethylene in an organic solvent in the presence of a Ziegler catalyst, and an organic solvent separated by distilling an obtained polymerization reaction product is circulated and used in the polymerization reaction. A method for producing a low polymer, wherein the concentration of the olefin having 3 or more carbon atoms contained in the organic solvent circulating in the polymerization reaction system is 2% by weight or less. 2. The method according to claim 1, wherein the organic solvent is selected from alicyclic compounds, aliphatic hydrocarbons, aromatic hydrocarbons, and halogen compounds thereof. 3. The production method according to claim 1, wherein the Ziegler-based catalyst contains Zr. 4. An olefin having 3 or more carbon atoms is converted into an olefin having 4 carbon atoms.
The method according to any one of claims 1 to 3, wherein the olefin is an olefin. 5. The production method according to claim 1, wherein the water concentration in the organic solvent circulating in the polymerization reaction system is 8 ppm by weight or less.