JP3289372B2 - Low polymerization method of α-olefin - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for low-polymerizing an α-olefin. More specifically, the present invention relates to a low-polymerization method of α-olefin, which can obtain a product mainly composed of a trimer, particularly from ethylene, in a high yield using a chromium-based catalyst.

[0002]

2. Description of the Related Art It has been known that an α-olefin such as ethylene is polymerized at a low polymerization rate using a catalyst comprising a combination of a specific chromium compound and a specific organic aluminum compound. For example, JP-B-43-18707 discloses a method for obtaining 1-hexene and polyethylene from ethylene using a catalyst system comprising a VIA transition metal compound containing Cr represented by the general formula MXn and polyhydrocarbyl aluminum oxide. JP-A-3-128904 describes that α-olefins can be prepared using a catalyst obtained by preliminarily reacting a chromium-containing compound having a chromium-pyrrolyl bond with a metal alkyl or Lewis acid. Methods for quantification are described.

On the other hand, the present inventors have previously established a method for performing a low-polymerization reaction of an α-olefin by specifying a contact method of a chromium-containing compound having a chromium-pyrrolyl bond, an α-olefin, and an alkylaluminum. Proposed. According to this method, 1-hexene can be obtained with surprisingly high activity, particularly by a low polymerization reaction of ethylene. Furthermore, the present inventors produced a chromium-containing compound having a chromium-pyrrolyl bond in a high yield without any complicated operation by using a hydrocarbon as a solvent, and by using this in combination with an alkylaluminum compound, α- A method was also proposed in which a low polymerization reaction of olefins, particularly a trimerization reaction of ethylene, can be performed with high activity to produce 1-hexene with high purity.

Recently, the present inventors have specified a method for contacting a chromium salt, an amine, an α-olefin, and an alkylaluminum compound, and have also proposed a method for performing a low-polymerization reaction of an α-olefin, particularly, a trimerization reaction of ethylene. Proposed.

[0005]

However, in the method described in Japanese Patent Publication No. 18707/1973, the amount of polyethylene produced simultaneously with 1-hexene is large, and if the amount of polyethylene is reduced, the overall activity is reduced. However, on the other hand, there is a problem that
The method described in Japanese Patent Publication No. 4 (1994) -104 has a problem that the amount of the high molecular weight polymer produced is small, but the catalytic activity is not sufficient.
The present invention solves the problems of the conventional methods as described above, and makes it possible to obtain a low-polymerized α-olefin, particularly 1-hexene, with high yield and high selectivity in an industrially advantageous manner. It is an object of the present invention to provide a novel method for low polymerization of α-olefin.

[0006]

Means for Solving the Problems The inventors of the present invention have made intensive studies to achieve the above object, and as a result, have been able to convert α-olefins, particularly ethylene, using a chromium catalyst comprising a chromium salt, an amine and an alkylaluminum compound. In the method of low polymerization, it has been found that by performing a low polymerization reaction in the presence of a non-conjugated diene, 1-hexene is generated with extremely high α-position selectivity, and the low polymerization reaction proceeds with a very high activity. The present invention has been completed.

That is, the gist of the present invention is to carry out a low polymerization reaction in the presence of a non-conjugated diene in a method of low polymerization of an α-olefin using a chromium catalyst comprising a chromium salt, an amine and an alkylaluminum compound. It is characterized by a low polymerization method of α-olefin. Hereinafter, the present invention will be described in more detail.

[0008] The chromium salt used in the present invention is
General formula CrXn (where the valence of chromium is monovalent to hexavalent)
X is the same or any organic or different
And n is an integer of 1 to 6. )
It is. The number n is preferably 2 or more. As an organic group
Represents a hydrocarbon group, a carbonyl group, an alkoxy group,
Xyl group, β-diketonate group, β-ketoester group and
And amide groups. The carbon number of the organic group is usually 1
To 30, and the hydrocarbon group is an alkyl group,
Alkyl group, aryl group, alkylaryl group, arral
And a kill group. Halogen, nitrate
Examples thereof include an acid group, a sulfate group, and oxygen. Preferably
Means chromium salt is alkoxy salt, carboxyl salt, β-di
Ketnerate salts, salts with β-ketoester anions,
Or a halide, specifically chromium (IV) tert.
Butoxide, chromium (III) acetylacetonate,
Rom (III) trifluoroacetylacetonate, chromium
(III) hexafluoroacetylacetonate, chromium (I
II) (2,2,6,6-tetramethyl-3,5-hepta)
Ionate), Cr (PhCOCHCOPh)_Three(However,
Here, Ph represents a phenyl group. ), Chrome (II) acete
Chromate (III) acetate, chromium (III) 2-ethyl
Hexanoate, chromium (III) benzoate, chromium (II
I) Naphthenate, Cr (CH_ThreeCOCHCOOCH_Three)_Three,
Chromic chloride, chromic chloride, chromic bromide, odor
Chromium iodide, chromium iodide, chromium iodide,
Chromic fluoride, chromic fluoride and the like can be mentioned.
Complexes consisting of these chromium salts and electron donors are also used.
Can be. As electron donors, nitrogen, oxygen,
It is selected from phosphorus and sulfur compounds. Nitrogen content
Examples of the compound include nitrile, amine, and amide.
Specifically, acetonitrile, pyridine, dimethyl
Pyridine, dimethylformamide, N-methylforma
Mid, aniline, nitrobenzene, tetramethylethylene
Diamine, diethylamine, isopropylamine,
Xamethyldisilazane, pyrrolidone and the like. acid
As the sulfur-containing compounds, esters, ethers, ketones,
Alcohol, aldehyde and the like.
Cyl acetate, methyl acetate, tetrahydrofura
, Dioxane, diethyl ether, dimethoxy eta
, Diglyme, triglyme, acetone, methylethyl
Ketone, methanol, ethanol, acetaldehyde
And the like. Hexamethylphne as a phosphorus compound
Osforamide, hexamethylphosphorustoria
Mid, triethyl phosphite, tributyl phosphite
Oxide, triethylphosphine, etc.
You. As sulfur-containing compounds, carbon disulfide, dimethyls
Rufoxide, tetramethylene sulfone, thiofe
And dimethyl sulfide. Therefore,
Examples of complexes consisting of a salt and an electron donor include halogenated
Chromium ether complex, ester complex, ketone complex,
Aldehyde complex, alcohol complex, amine complex, phosphite
Complexes, thioether complexes and the like, and specifically,
CrCl_Three・ 3THF, CrCl_Three・ 3dioxane,
CrCl_Three・ (CH_ThreeCO_TwonC_FourH₉), CrCl_Three・
(CH_ThreeCO_TwoC_TwoH_Five), CrCl_Three・ 3 (ic_ThreeH₇O
H), CrCl_Three・ 3 [CH_Three(CH_Two)_ThreeCH (C_TwoH_Five)
CH_TwoOH], CrCl_Three・ 3pyridine, CrC
l _Three・ 2 (ic_ThreeH₇NH_Two), [CrCl_Three・ 3CH_ThreeC
N] ・ CH_ThreeCN, CrCl_Three・ 3PPh_Three, CrCl_Two・
2THF, CrCl_Two・ 2pyridine, CrCl_Two
・ 2 [(C_TwoH_Five)_TwoNH], CrCl_Two・ 2CH_ThreeCN, C
rCl_Two・ 2 [P (CH_Three)_TwoPh] and the like. K
As the rom salt, a compound soluble in a hydrocarbon solvent is more preferable.
Chromium β-diketonate salt, chrome carbo
Salts of chromium with β-ketoester anions,
Β-ketocarboxylate of chromium, amide complex of chromium,
Chromium carbonyl complex, chromium various cyclopentadi
Enyl complexes, alkyl complexes, phenyl complexes, etc.
You. Various cyclopentadienyl complexes of chromium, alkyl
Complexes, phenyl complexes and the like include CpCrCl_Two(here
And Cp represents a cyclopentadienyl group. ), (Cp * C
rClCH_Three)_Two(Where Cp * is pentamethylcyclopen
Represents a tadienyl group. ), (CH_Three)_TwoExamples include CrCl
Is done.

Further, instead of the chromium salt and the amine which are the chromium catalyst of the present invention, for example, a chromium-containing compound having a chromium-pyrrolyl bond can be used. The chromium-containing compound having a chromium-pyrrolyl bond can be obtained by reacting the chromium salt and the metal pyrrolide exemplified above in a solvent. Metal pyrrolides refer to those derived from pyrrole and derivatives of pyrrole, and pyrrole derivatives include 2,5-dimethylpyrrole, 3,4
-Dimethylpyrrole, 3,4 dichloropyrrole, 2,
3,4,5-tetrachloropyrrole, 2-acylpyrrole and the like, and as the metal, IA group containing hydrogen,
Selected from Group IA, Group IIIB, and Group IVB.
Preferred metal pyrrolides include lithium pyrrolide, sodium pyrrolide, potassium pyrrolide, cesium pyrrolide and the like. Pyrrole and pyrrole derivatives themselves may be used instead of metal pyrrolide.

In the present invention, by using a chromium salt and an amine as a chromium catalyst, it is not necessary to once synthesize and isolate a chromium-containing compound having a chromium-pyrrolyl bond which is extremely unstable to air or humidity.
Therefore, in addition to the α-olefin low polymerization process, there is no need to go through the chromium-containing compound production step and the isolation step,
Further, there is an advantage that a storage tank for the unstable compound is not required, and the construction cost for the entire manufacturing process is reduced.

In the present invention, a chromium salt or a chromium-containing compound containing a chromium-pyrrolyl bond can be used by being supported on a carrier such as an inorganic oxide. And / or it may be used simply in combination with an amine. The low polymerization of α-olefin in the present invention,
Usually carried out in a hydrocarbon solvent, the concentration of the chromium salt and the chromium-containing compound is 0.1 m / l of solvent.
g to 5 g, preferably 1 mg to 2 g.

The amine, which is another component of the catalyst system of the present invention, is a primary or secondary amine, a metal amide derived from a primary or secondary amine, and a mixture thereof. Shall be called. Examples of the primary amine include ammonia, ethylamine, isopropylamine, cyclohexylamine, benzylamine, aniline, and naphthylamine. Examples of the secondary amine include diethylamine, diisopropylamine, dicyclohexylamine, dibenzylamine, and 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 Etc. are exemplified. Examples of the metal amide derived from a primary or secondary amine include the primary or secondary amine exemplified above and IA
Amides obtained by reaction with a metal selected from Group IIA, Group IIA, Group IIIB, and Group IVB, such as lithium amide, sodium ethylamide, calcium (ethylamide), lithium diisopropylamide, potassium benzylamide, sodium bisamide Examples thereof include (trimethylsilyl) amide, lithium indolide, sodium pyrrolide, lithium pyrrolide, potassium pyrrolide, potassium pyrrolidide, aluminum diethylpyrrolide, ethylaluminum dipyrrolide, and aluminum tripyrolide. As the amine, a secondary amine, or an amide derived from a secondary amine, and a mixture thereof are preferable. Specifically, pyrrole, 2,5-dimethylpyrrole, 3,4-dimethylpyrrole, 3,3 4-dichloropyrrole, 2,3,4,5
-Tetrachloropyrrole, 2-acylpyrrole, and aluminum pyrrolide, ethylaluminum dipyrrolide, aluminum tripyrolide, sodium pyrrolide, lithium pyrrolide, potassium pyrrolide and the like.

The amount of the amine to be used may be 0.001 equivalent or more relative to the chromium salt. The upper limit is not particularly limited, but it is not necessary to use an unnecessarily large amount of the amine. A preferred amount of the amine to be used is 0.005 to 1000 equivalents, more preferably 0.01 to 100 equivalents, based on the chromium salt.

In the present invention, a low polymerization reaction of an α-olefin is carried out by combining the above chromium salt with an amine and an alkylaluminum compound. As the alkylaluminum compound, the following general formula: R ¹ _m Al (OR ² ) _{n Hp} X _q (1) (wherein, R ¹ and R ^{2 each} have 1 to 15 carbon atoms, preferably 1 to 15 carbon atoms. To 8 hydrocarbon groups which may be the same or different, X represents a halogen atom, m is 0 <m ≦ 3, n is 0 ≦ n <3, and p is 0 ≦ p < 3, q is 0
≤q <3, and m + n + p +
represents a number where q = 3. Alkyl aluminum compounds are preferred which are represented by) a compound represented by general formula (2) can be exemplified by the _{^{~ (5), R 1 3}} Al ··· (2) ( In the formula, R ¹ is as defined above R ¹ _m AlX _3-m (3) (wherein R ¹ and X are the same as above; m is 1.5 ≦ m <3)
It is. R ¹ _m Al (OR ² ) _{3 -m} (4) (wherein R ¹ and R ² are the same as above; m is 0 <m <3, preferably Is an alkoxyaluminum compound represented by the formula: 1.5 ≦ m <3), R ¹ _m AlH _3−m (5) (wherein, R ¹ is the same as above; m is 0 <m <3) , Preferably 1.5 ≦ m <3). Specific examples include trimethylaluminum, triethylaluminum, triisobutylaluminum, diethylaluminum monochloride, diethylaluminum ethoxide, diethylaluminum hydride and the like. Among these alkylaluminum compounds, trimethylaluminum, triethylaluminum, diethylaluminum hydride and the like are exemplified. More preferred.

The amount of the alkylaluminum compound used is
It is at least 0.1 mmol / g of chromium salt, but is preferably larger than 5 mmol / g of chromium salt from the viewpoint of improving the activity and trimer selectivity. The non-conjugated diene used in the present invention includes 1,5-hexadiene, 2,5-hexadiene, 1,6-diphenyl-2,5-hexadiene,
1,6-heptadiene, 2,5-heptadiene, 1,5
Chain non-conjugated dienes such as 1,6-octadiene, 2,6-octadiene, 1,7-octadiene, 1,5-cyclooctadiene, norbornadiene, dicyclopentadiene,
-Vinylcyclohexene, hexamethylbicyclo [2,
2,0] hexadiene, 1,4-cyclohexadiene,
Examples include cyclic non-conjugated dienes such as 1,4-cycloheptadiene. These are an alkyl group like an exemplary compound,
It may have an aliphatic or aromatic hydrocarbon group such as an aralkyl group or an aryl group as a substituent. The non-conjugated diene to be used is preferably a non-conjugated diene having 20 or less carbon atoms, and among these, a cyclic non-conjugated diene is preferable in view of easiness of coordination with a chromium atom.

The amount of the non-conjugated diene in the liquid phase is at least 0.1 ppm, preferably at least 10 ppm, and there is no particular upper limit, and substantially 100%, that is, a solvent amount may be used. More preferably, it is in the range of 0.1% to 20% of the charged solution amount. In the present invention, when the α-olefin, particularly ethylene, is subjected to a low polymerization reaction in the presence of a non-conjugated diene, the purity and activity of the produced α-olefin are improved. By coordinating the non-conjugated diene to a chromium catalyst prepared from a chromium salt, an amine, and an alkylaluminum compound, the formation of positional isomers of double bonds contained in hexenes is suppressed. It is considered that the purity is improved. Further, it is considered that the non-conjugated diene coordinates to the chromium atom, thereby increasing the electron density on the chromium atom, and as a result, the low polymerization reaction activity of the electron-rich chromium catalyst itself is improved. The non-conjugated diene used in the present invention may be added to the reaction system by any method.

In the present invention, these chromium salts, amines,
And the chromium catalyst comprising an alkylaluminum compound becomes an active species and low polymerization of α-olefin occurs.
It is preferable to supply the α-olefin and the chromium catalyst to the reaction system without previously contacting the chromium salt with the alkylaluminum compound. For this purpose, the most reliable method is to prevent physical contact between the chromium salt and the alkylaluminum compound in advance, and specifically, (1) a solution containing an amine and an alkylaluminum compound, In a solution containing (2) a chromium salt and an amine for introducing an olefin and a chromium salt, α
An olefin and an alkylaluminum compound, (3) a solution containing a chromium salt, an α-olefin, an amine and an alkylaluminum compound, and (4) an α-olefin in a solution containing an alkylaluminum compound. A method of introducing a chromium salt and an amine and (5) simultaneously introducing a chromium salt, an amine, an alkylaluminum compound and an α-olefin into a reaction system independently of each other can be considered.

When the chromium salt is reacted with the alkylaluminum compound in advance, the low polymerization reaction activity of the α-olefin becomes lower as compared with other reaction methods. Although the reason for this is not yet clear, when a chromium salt is reacted with an alkylaluminum, a ligand coordinated to the chromium salt,
It is thought that the ligand exchange reaction proceeds with the alkyl group in the alkylaluminum compound, but the alkyl-chromium compound generated at this time is unstable by itself, and the decomposition-reduction reaction of the alkyl-chromium compound is difficult. It is presumed that the polymerization proceeds preferentially, and as a result, unsuitable demetalation occurs in the low polymerization reaction, so that the low polymerization reaction activity of the α-olefin decreases.

The reaction temperature in the present invention is from 0 to 250 ° C, preferably from 0 to 150 ° C. The reaction pressure is from normal pressure to 250 kg / cm ² , but 100 kg / cm ² or less is sufficient. In the present invention, a low polymerization reaction is carried out using a solvent, butane, pentane, hexane, heptane, octane, cyclohexane, methylcyclohexane, linear or alicyclic saturated hydrocarbons such as decalin,
Aromatic hydrocarbons such as benzene, toluene, xylene, ethylbenzene, mesitylene, and tetralin; chain chlorinated hydrocarbons such as chloroform, carbon tetrachloride, methylene chloride, dichloroethane, trichloroethane, and tetrachloroethane; and chlorine such as chlorobenzene and dichlorobenzene Aromatic hydrocarbons and the like are used as solvents. Among these solvents, linear or alicyclic saturated hydrocarbons are preferred. The α-olefin itself as a reaction raw material or an α-olefin other than the main raw material for the reaction can be used as a solvent. As these α-olefins, those having 4 to 30 carbon atoms are used,
Those which are liquid at room temperature are particularly preferred. Also, a mixture of the compounds exemplified here may be used as a reaction solvent without any problem.

The starting α-olefin used in the present invention is a substituted or unsubstituted one having 2 to 30 carbon atoms. Specific examples include ethylene, propylene,
1-butene, 1-hexene, 1-octene, 3-methyl-1-
Butene, 4-methyl-1-pentene and the like. In particular, the present invention is suitable for low-polymerization of ethylene, and can obtain 1-hexene with high activity and high selectivity.

The reaction can be carried out either batchwise or continuously. The residence time is in the range of 1 minute to 20 hours, preferably 0.5 to 6 hours. In the low polymerization of α-olefin of the present invention, hydrogen can coexist during the reaction. It is preferable that the activity and the trimer selectivity be improved by the coexistence of hydrogen.

[0022]

The present invention will be described in more detail with reference to the following Examples and Comparative Examples. However, the present invention is not limited to the following Examples unless it exceeds the gist thereof. Example 1 A 300 ml autoclave heated and dried in a dryer at 150 ° C. was assembled while hot, and the atmosphere was replaced with vacuum nitrogen. The autoclave is fitted with a catalyst feed tube with a rupture disk. Heptane (47 ml), a solution of triethylaluminum in heptane (0.4 mmol, 1 ml), a solution of pyrrole in heptane (1.3 ml, 0.0625 mmol),
And 1,5-cyclooctadiene (9.41 mmol
l) was charged into the autoclave cylinder side, while chromium (III) 2-ethylhexanoate (1) was added to the catalyst feed tube.
(0 mg, 0.0208 mmol) in heptane (1 ml). At this point, the chromium salt and triethylaluminum are not in contact. 10 autoclaves
The mixture was heated to 0 ° C., and then ethylene was introduced at 100 ° C. through a catalyst feed tube. The rupture disk ruptured due to ethylene pressure, chromium salt was introduced into the autoclave barrel side, and low polymerization of ethylene started. Ethylene with a total pressure of 35 kg / cm
After that, the total pressure was maintained at 35 kg / cm 2 and the reaction temperature was maintained at 100 ° C. One hour later, the reaction was stopped by injecting ethanol, and the product was quantified by gas chromatography. Table 1 shows the reaction conditions and results. Comparative Example 11 The reaction was carried out in the same manner as in Example 1 except that 1,5-cyclooctadiene was not added. Table 1 shows the reaction conditions and results.

[0023]

[Table 1]

[0024]

According to the method of the present invention, α-olefin,
In particular, a low-polymerization of ethylene can selectively obtain a product mainly composed of a trimer, particularly 1-hexene having a high α-selectivity in a high yield, and can produce a high-molecular-weight polymer. It can provide significant industrial benefits because it can be controlled.

──────────────────────────────────────────────────続 き Continuation of the front page (56) References JP-A-3-128904 (JP, A) JP-A-62-265237 (JP, A) JP-A-6-157655 (JP, A) JP-A-6-157655 145241 (JP, A) JP-A-6-157654 (JP, A) (58) Fields investigated (Int. Cl. ⁷ , DB name) C08F 4/60-4/70 B01J 21/00-38/74 C07C 1/00-409/44

Claims (4)

(57) [Claims] 1. A method for low polymerization of an α-olefin using a chromium catalyst comprising a chromium salt, an amine and an alkylaluminum compound, wherein the low polymerization reaction is carried out in the presence of a non-conjugated diene. Low polymerization method. 2. The method of claim 1, wherein the α-olefin and the chromium salt are introduced into a solution containing an amine and an alkylaluminum compound. 3. In a solution containing a chromium salt and an amine,
The method for low polymerization of an α-olefin according to claim 1, wherein an α-olefin and an alkylaluminum compound are introduced. 4. The method for low polymerization of α-olefin according to claim 1, wherein the α-olefin is ethylene and the main product is 1-hexene.