JPH07215896A - Production of alpha-olefin oligomer - Google Patents

Abstract

PURPOSE:To efficiently obtain an alpha-olefin oligomer improved in selectivity of trimer and tetramer of ethylene, hexene-l and octene-1 and useful as a comonomer of linear low density PE in high selectivity and yield by using a specific catalyst composition. CONSTITUTION:This alpha-olefin oligomer is obtained by using a catalyst composition composed of (A) a chromium compound such as a trivalent to hexavalent chromium compound containing oxygen anion as a ligand [e.g. chromium (3)tris(2-ethylhexanoate)], (B) an electron donating agent such as an ether selected from THF, dimethoxyethane, 2,3-dihydrofuran and 3,4-dihydro-2H-pyran or amines, (C) aluminum alkoxide obtained by reaction of an organoaluminum compound with an alcohol or alkoxide and further preferably (D) a reducing agent such as an organoaluminum compound. Furthermore, the component C is preferably used in a molar ratio of 1-10000 based on the component A.

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 .alpha.-olefin oligomer, and more specifically, it selectively selects hexene-1 and octene-1 which are particularly useful as comonomers for linear low density polyethylene (L-LDPE). The present invention relates to a method for producing an α-olefin oligomer which can be efficiently produced.

[0002]

2. Description of the Related Art Recently, α-olefins having 4 to 12 carbon atoms, particularly hexene-1 and octene-1, are known to be useful compounds as linear low density polyethylene (L-LDPE) comonomers. It is also known that these α-olefins can be produced by ethylene oligomerization and the like. The ethylene oligomerization technology has been industrialized as an oligomer production technology according to Schulz-Flory law and an oligomer production technology represented by Poisson distribution. In the former technique, the molecular weight distribution of the oligomer is displayed as an α value,
When the α value is 0.5, the production amount of butene-1 is large, and when the α value is 0.7, the production amount of high molecular weight α-olefin having 10 or more carbon atoms is large, and a comonomer for L-LDPE is selectively produced. It cannot be manufactured. On the other hand, the latter technique can relatively selectively produce an α-olefin having 6 or 8 carbon atoms. However, detailed analysis of the ethyl ester oligomer manufacturing technology that employs this technology, the so-called modified ethyl method, recycles the olefin having 4 carbon atoms that is generated, or divides the reaction process into two steps, an alkyl step and a substitution step. Besides, it is a complicated process in which the catalyst has to be used for the stoichiometry. That is, although the ethylene oligomerization mentioned here, particularly the trimerization technology is a technology that has been known for a long time, the production of the polymer cannot be suppressed, or the activity cannot be increased unless a solid acid catalyst is used together. The oligomer production technology has many problems.

In the above-mentioned oligomer production technology, an ethylene trimerization catalyst using a chromium element has been known as an olefin oligomerization catalyst.
However, in the case of the chromium carboxylate-based catalyst disclosed in, for example, Japanese Patent Publication No. 4-66457, only hexene-1 was produced as an oligomer, and the catalytic activity was low. In addition, Japanese Patent Laid-Open No. 3-115406
In the case of the chromium pyrrolide-based catalyst disclosed in Japanese Patent Publication, although the amount of polymer produced can be reduced to several percent or less, there is a problem that the reaction rate is slow. In order to increase the reaction rate like this, it is necessary to use a solid acid.
When a solid acid insoluble in a hydrocarbon solvent was used in the reaction, a filtration treatment step was added to the post-treatment of the reaction, and the process construction such as preparation of the solid acid and addition of powder was difficult.

[0004]

Under the circumstances described above, the present invention is particularly directed to linear low density polyethylene (L-LD).
PE), which is useful as a comonomer, and hexene-1 and octene-1 can be selectively and efficiently produced by oligomerization of olefins, particularly ethylene, and is industrially advantageous.
-It was made for the purpose of providing a method for producing an olefin oligomer.

[0005]

That is, the present invention is
(1) A method for producing an α-olefin oligomer characterized by using a catalyst composition comprising a chromium compound, an electron donor and an aluminum alkoxide, (2) As an aluminum alkoxide, an organoaluminum compound and an alcohol or an alkoxide The compound obtained from the reaction is used, and α as described in (1) above is used.
A method for producing an olefin oligomer, (3) a method for producing an α-olefin oligomer according to the above (2), wherein a secondary or tertiary alcohol or alkoxide is used as the alcohol or alkoxide;
(4) As the aluminum alkoxide, a reaction product obtained by subjecting a trialkylaluminum to alcoholysis with an alcohol is used, (1) above
(5) The method for producing an α-olefin oligomer according to any one of (3) to (3) above, wherein (5) the aluminum alkoxide is used in a molar ratio of 1 to 10,000 with respect to the chromium compound. 1) A method for producing an α-olefin oligomer according to any one of (4),
(6) The method for producing an α-olefin oligomer according to any one of (1) to (5) above, which further comprises using a catalyst composition containing a reducing agent, and (7) the reducing agent is an organoaluminum compound. (1) above, which is characterized in that
(6) The method for producing an α-olefin oligomer according to any one of (6), (8) wherein the chromium compound is a trivalent to hexavalent chromium compound having an oxygen anion as a ligand. (9) The method for producing an α-olefin oligomer according to any one of (7) to (7), (9) the electron donor is an ether or an amine.
To (8) the method for producing an α-olefin oligomer, (10) the electron donor is selected from the group consisting of tetrahydrofuran, dimethoxyethane, 2,3-dihydrofuran, and 3,4-dihydro-2H-pyran. The method for producing an α-olefin oligomer according to any one of (1) to (9) above, characterized in that
1) The electron donor is 0.1 in molar ratio to the chromium compound.
The method for producing an α-olefin oligomer according to any one of the above (1) to (10), characterized in that the method is used in a proportion of 10,000 to 10,000.

The present invention will be described in more detail below. As the chromium compound constituting the catalyst composition used in the production method of the present invention, a chromium compound in which the oxidation state of chromium is 0 to 6 is used, and preferably divalent to hexavalent having an oxygen anion as a ligand. A valent chromium compound is used, more preferably a trivalent or tetravalent chromium compound. The chromium compound is not particularly limited, but examples thereof include carboxylates such as chromium (3) tris (2-ethylhexanoate), chromium (3) tris (cyclohexylcarboxylate), and trisacetyl. Β-such as acetonatochrome and tris (2,2,6,6-tetramethyl-3,5-heptanedionato) chrome
Examples thereof include chelate salts of diketone, and alcoholates such as chromium (4) tetraethoxide and chromium (4) tetra-t-butoxide. These chromium compounds may be used alone or in combination of two or more.

An electron donor is used in the catalyst composition used in the production method of the present invention. Such an electron donor may be a substance capable of donating an electron to the chromium center, for example, cyclic ethers such as tetrahydrofuran, pyran and dioxane, chain ethers such as dimethoxyethane, diethylene glycol dimethyl ether and triethylene glycol dimethyl ether, Two
Cyclic vinyl ethers such as 3-dihydrofuran, 3,4-dihydro-2H-pyran, chain vinyl ethers such as methyl vinyl ether and ethyl vinyl ether, 2,5-dihydrofuran, 5,6-dihydro-2H
-Cyclic allyl ethers such as pyran, chain allyl ethers such as methyl allyl ether and ethyl allyl ether, aliphatic amines such as triethylamine and triethylenediamine, aromatic amines such as pyridine and picoline, 2-oxazoline, Heterocyclic compounds such as 6H-1,2,4-oxadiazine and the like can be mentioned. Among these, tetrahydrofuran, dimethoxyethane,
2,3-dihydrofuran, 3,4-dihydro-2H-pyran and the like are preferably used. These electron donors may be used alone or in combination of two or more.

Further, aluminum alkoxide is used in the catalyst composition used in the production method of the present invention. The aluminum alkoxide is preferably an organoaluminum alkoxide, more preferably one having 1 to 3 alkoxides with respect to an aluminum atom, and particularly preferably a compound obtained by reacting an organoaluminum compound with an alcohol or an alkoxide. To be Examples of such aluminum alkoxides include reaction products obtained by alcoholysis of trialkylaluminums such as trimethylaluminum, triethylaluminum, and isobutylaluminum with alcohols, hydrides such as dibutylaluminum hydride and diethylaluminum hydride, and alcohols. Reaction product with, diethylaluminium chloride,
Aluminum alkoxide and the like obtained by the reaction of dibutylaluminum chloride and a metal alcoholate are used. The alcohol used for the preparation of the aluminum alkoxide is preferably a secondary or tertiary alcohol. For example, an aluminum alkoxide composed of a primary alcohol such as n-butanol tends to have a poor ethylene reaction progress. The metal alcoholate is preferably a metal alcoholate of a secondary or tertiary alcohol, and the metal constituting the metal alcoholate is preferably a metal of Group 1 of the periodic table such as lithium, sodium and potassium. The aluminum alkoxide may be used alone or in combination of two or more.

In the production method of the present invention, it is preferable to use a reducing agent, if necessary, particularly when a trivalent or tetravalent chromium compound is used. As such a reducing agent, any substance capable of reducing the chromium compound may be used, but preferably organic aluminum such as trimethylaluminum, triethylaluminum and triisobutylaluminum, organic such as dimethylzinc, diethylzinc and dibutylzinc. Zinc, lithium aluminum hydride, sodium borohydride, diethyl aluminum hydride, dibutyl aluminum hydride, sodium hydride, lithium hydride and other hydrides, lithium, sodium, potassium,
A metal such as magnesium or aluminum, or an inorganic or organic compound having an action of reducing a trivalent or hexavalent chromium compound is used. Organic aluminum such as trimethylaluminum, triethylaluminum and triisobutylaluminum is particularly preferably used.

The amount of each component of the catalyst composition used in the production method of the present invention depends on the type of chromium compound, but in the case of aluminum alkoxide, it is generally 1 to 1 in terms of molar ratio to the chromium compound. It is used in the range of 10,000, preferably 10 to 5,000, and more preferably 20 to 1,000. When the molar ratio is lower than 1, the oligomer activity is low, and when it is higher than 10,000, the amount of polymer is increased. The electron donor is used in a molar ratio of 0.1 to 10,000, preferably 1 to 500, with respect to the chromium compound.
It is used in the range of 0, more preferably 2 to 2000.
In this case, when the molar ratio is lower than 0.1, polymer formation is dominant, and when it exceeds 10,000, the oligomer activity decreases. Further, the reducing agent is in a molar ratio of 0 to 10,000, preferably 1 to 500 with respect to the chromium compound.
It is used in the range of 0, more preferably 1 to 2000.
Here, the amount of the reducing agent used is an amount sufficient to divalently reduce the chromium compound as the raw material, and is appropriately determined depending on the type of the reducing agent.

The catalyst composition used in the production method of the present invention can be prepared by various methods. Specifically, for example, a mixed solution of a chromium compound and an electron donor is added to an aluminum alkoxide (alcohol is used). Organoaluminum compound obtained by alcoholysis) is added. Preferably, for example, in the case where an organoaluminum compound having a reducing power is added to a mixed solution of a chromium compound (3 to 6 valent) and an electron donor to obtain a chromium complex in which the valence of chromium is reduced to divalent or -A method such as adding an alkoxide can be used. In addition, since the electron donor plays an important role in the reduction of the chromium compound in the preparation of this catalyst composition, when used as a catalyst, a portion of the electron donor is appropriately distilled off to obtain the optimum electron for the oligomerization reaction. The amount of the donor can be adjusted. Α of the present invention
The olefin used in the method for producing an olefin oligomer is an α-olefin, and, for example, ethylene, propylene, butene-1, isobutylene, pentene-1, hexene-1, heptene-1, various octenes and a mixture thereof are used. Among these, among these,
Ethylene is particularly preferable. An inert solvent is usually used in the polymerization of the olefin. Examples of such an inert solvent include pentane, hexane, heptane,
Examples thereof include aliphatic hydrocarbons such as octane, alicyclic hydrocarbons such as cyclopentane, cyclohexane and methylcyclohexane, and aromatic hydrocarbons such as benzene, toluene, xylene and ethylbenzene. These solvents may be used alone or in combination of two or more.

The reaction temperature is usually -10 to 200.
C., preferably in the range of 20 to 150.degree. C. In the present invention, the optimum reaction temperature varies depending on the type of electron donor used. For example, when an ether such as dimethoxyethane, tetrahydrofuran or dioxane is used as the electron donor, it is 50 to 150 ° C., and further 8
The reaction temperature is preferably 0 to 130 ° C, and when the cyclic or chain vinyl ether is used as the electron donor, the reaction temperature is preferably -10 to 100 ° C, more preferably 20 to 80 ° C. Reaction pressure is usually atmospheric pressure to 200 kg / c
m ² , preferably selected in the range of 5 to 100 kg / cm ² . The higher the pressure is, the more the reaction can be promoted, but if it exceeds 200 kg / cm ² , the temperature control of the reaction may be difficult in some cases. Further, the amount of the catalyst charged is selected so that the chromium concentration is in the range of 10 ⁻³ to 50 mmol / liter, preferably 10 ^{−2 to} 5 mmol / liter. In the production method of the present invention, it is preferable to react with a chromium compound, an electron donor, an aluminum alkoxide, and a reducing agent under the combined conditions of the preferable conditions described in detail. The production method of the present invention is preferably applied to simultaneously produce hexene-1 and octene-1 using ethylene as a raw material.
That is, hexene-1 and octene-1, which are useful as comonomers of linear low-density polyethylene, can be selectively and efficiently produced by appropriately selecting the production conditions and reaction conditions of the catalyst.

[0013]

The present invention will be described in more detail with reference to examples, but the present invention is not limited to these examples. Preparation Example 1 [Organoaluminum-t-butoxide] To a Schlenk tube having an inner volume of 300 ml, 8.6 g (0.126 mmol) of t-butanol and cyclohexane were added to make a solution of 108 ml. A cyclohexane solution of triisobutylaluminum (TIBA) (1.0 mol / liter) was added dropwise to this solution, and stirring was continued until the generation of gas stopped. The cyclohexane solution of aluminum-t-butoxide prepared in this way was 0.
It contained 46 mol / liter of aluminum.

Preparation Example 2 [Organoaluminum Adamantoxide] The same procedure as in Preparation Example 1 was repeated except that t-butanol (8.6 g, 0.126 mmol) was replaced with adamantanol (0.126 mmol). Organoaluminum adamantoxide was prepared. The cyclohexane solution of organoaluminum adamantoxide prepared in this manner contained 0.46 mol / liter of aluminum. Preparation Example 3 [Organoaluminum Bornoxide] Borneol (0.126 mmol) was used instead of 8.6 g (0.126 mmol) of t-butanol in Preparation Example 1.
Organoaluminum boroxide was prepared in the same manner except that was used. The cyclohexane solution of organoaluminum bornoxide thus prepared contained 0.46 mol / liter of aluminum.

Example 1 Chromium 2-ethylhexanoate [valence 3] 0.481 g (1
(Mmol) was weighed in a Schlenk tube, and cyclohexane was added to bring the total amount to 100 ml to dissolve chromium. This chrome liquid is dark green and has a chrome concentration of 10
It was mmol / l. Next, 0.90 g (10 mmol) of 1,2-dimethoxyethane was weighed in a Schlenk tube, and cyclohexane was added to make a total amount of 200 ml. The electron donor concentration of this liquid was 50 mmol / liter. 2.5 ml of the above chromium solution (Cr:
To 25 μmol), 20 ml of the above dimethoxyethane solution (1 mmol of electron donor) was added and stirred for 5 minutes. To this solution, 20 ml of the solution of the organoaluminum-t-butoxide prepared in Preparation Example 1 (A
l: 9.2 mmol) and 1.5 ml (1.5 mmol) of a 1 mol / l solution of TIBA in cyclohexane. Then, in order to make the total amount of the catalyst liquid 50 ml, 6 ml of cyclohexane was added, and 3
Stir for 0 minutes. The catalyst liquid changed from green (chrome valence 3) to ocher (chrome valence 2) by the reduction treatment. Next, the catalyst solution prepared above was poured into a fully degassed and dried autoclave having an internal volume of 200 ml. The contents were stirred at 200 rpm and the temperature was raised to 100 ° C.
While maintaining the reaction temperature at 100 ° C., ethylene gas was fed in to adjust the holding pressure to 35 Kg / cm ² (gauge pressure). After a reaction time of 23 minutes, the mixture was cooled and depressurized. After the polymer was filtered off from the reaction solution, the product was analyzed by gas chromatography. The total amount of ethylene reactant was 3.14 g, and hexene-1 was obtained in a yield of 2.64 g. The selectivity of each product is 84% by weight of hexene-1, 3% by weight of octene-1, 11% by weight of polymer, the balance being 10 carbon atoms.
It was the above olefin.

Example 2 A catalyst was prepared in the same manner as in Example 1 except that the organoaluminum adamantoxide prepared in Preparation Example 2 was used instead of the organoaluminum-t-butoxide prepared in Preparation Example 1. Was prepared and the reaction was carried out. Example 1
At one-third of the ethylene reaction amount (reaction time 214
Min) the reaction was stopped and the product analyzed. Total yield
At 0.93 g, a selectivity for hexene-1 of 47% by weight was obtained.

Example 3 A catalyst was prepared in the same manner as in Example 1 except that the organoaluminum-boronoxide prepared in Preparation Example 3 was used in place of the organoaluminum-t-butoxide prepared in Preparation Example 1. Prepared and reacted. At the same ethylene reaction amount as in Example 1 (reaction time 23 minutes), the reaction was stopped and the product was analyzed. The total yield is 3.56g,
A selectivity of hexene-1 was obtained with a result of 76% by weight.

Example 4 In Example 1, 1.5 ml of a 1 mol / liter TIBA solution in cyclohexane was used.
A catalyst was prepared and reacted in the same manner as in Example 1 except that the amount was changed to milliliter (1 mmol). The reaction was stopped at 73 minutes, and 3.18 g of an ethylene reaction product was obtained. The selectivity of each product is 78% by weight of hexene-1 and octene-
1 was 6% by weight and the polymer was 15% by weight.

Example 5 In Example 4, at 20 ml of the solution of the organoaluminum-t-butoxide prepared in Preparation Example 1,
A catalyst was prepared and reacted in the same manner as in Example 4 except that the amount was 10 ml (Al: 4.2 mmol). The reaction was stopped at 202 minutes, and 2.78 g of a reaction product of ethylene was obtained. The selectivity of each product was 67% by weight of hexene-1, 4% by weight of octene-1, and 27% by weight of polymer.

Example 6 In Example 4, 20 ml of the solution of the organoaluminum-t-butoxide prepared in Preparation Example 1 was added,
A catalyst was prepared and reacted in the same manner as in Example 4 except that 10 ml (Al: 4.2 mmol) was used, and 20 ml of the dimethoxyethane solution was changed to 10 ml (electron donor 0.5 mmol). . The reaction was stopped at 68 minutes, and 2.89 g of a reaction product of ethylene was obtained. The selectivity of each product is such that hexene-1 is 76% by weight and octene-
1 was 5% by weight and the polymer was 17% by weight.

Comparative Example 1 A catalyst was prepared and reacted in the same manner as in Example 1 except that the organoaluminum-t-butoxide prepared in Preparation Example 1 was not added. Reaction time 12
The reaction of consuming ethylene did not occur even after 0 minute.

[0022]

As described in the production method of the present invention, by using an aluminum alkoxide as a cocatalyst,
Linear low-density polyethylene (L-LDPE) compared to oxygen-containing aluminum compounds obtained by hydrolysis with water
It is possible to improve the selectivity of ethylene trimerization product, hexene-1 and octene-1, which are useful as comonomers.

Claims (11)

[Claims] 1. A method for producing an α-olefin oligomer, which comprises using a catalyst composition comprising a chromium compound, an electron donor and an aluminum alkoxide. 2. The method for producing an α-olefin oligomer according to claim 1, wherein a compound obtained by reacting an organoaluminum compound with an alcohol or an alkoxide is used as the aluminum alkoxide. 3. The method for producing an α-olefin oligomer according to claim 2, wherein a secondary or tertiary alcohol or alkoxide is used as the alcohol or alkoxide. 4. The α-olefin oligomer according to claim 1, wherein a reaction product obtained by alcoholysis of trialkylaluminum with alcohol is used as the aluminum alkoxide. Production method. 5. The method for producing an α-olefin oligomer according to claim 1, wherein the aluminum alkoxide is used in a molar ratio of 1 to 10,000 with respect to the chromium compound. . 6. The α- according to claim 1, further comprising a catalyst composition containing a reducing agent.
Process for producing olefin oligomer. 7. The α- according to claim 1, wherein the reducing agent is an organoaluminum compound.
Process for producing olefin oligomer. 8. The method for producing an α-olefin oligomer according to claim 1, wherein the chromium compound is a trivalent to hexavalent chromium compound having an oxygen anion as a ligand. 9. The method for producing an α-olefin oligomer according to claim 1, wherein the electron donor is an ether or an amine. 10. The electron donor according to claim 1, wherein the electron donor is selected from the group consisting of tetrahydrofuran, dimethoxyethane, 2,3-dihydrofuran and 3,4-dihydro-2H-pyran. A method for producing the described α-olefin oligomer. 11. The α-olefin oligomer according to claim 1, wherein the electron donor is used in a molar ratio of 0.1 to 10,000 with respect to the chromium compound. Production method.