JP2002193847A - METHOD FOR PRODUCING LINEAR alpha-OLEFIN - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a method for efficiently producing a high-purity linear α-olefin in a simple operation with improved catalytic activity and suppressed byproduct polymer formation. SOLUTION: This method for producing a linear α-olefin comprises oligomerization of ethylene in the presence of a Ziegler-Natta type catalyst; wherein the above catalyst is characterized by being prepared by incorporating an organometallic compound as the cocatalyst with 0.05-1 molar time, based on the organometallic compound, of a heterocompound with the electron density of the heteroatom determined by molecular orbital calculation being 5.8-6.5.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a method for producing a linear α-olefin, and more particularly, to a method for producing a linear α-olefin by oligomerizing ethylene in the presence of a Ziegler-Natta type catalyst. It relates to a method for efficiently manufacturing.

[0002]

2. Description of the Related Art Alpha-olefins are widely used as monomers of olefin polymers or comonomers of various high molecular polymers, and are produced by oligomerizing ethylene in the presence of a Ziegler-Natta type catalyst. . In particular, the demand for olefins such as C6 and C8, which are recently used as comonomers for polyolefins, is increasing year by year. In order to efficiently produce such an oligomer, the catalytic activity usually needs to be low to some extent. Therefore, in the production of α-olefin, a catalyst having low catalytic activity is generally used. However, from the viewpoint of catalyst cost, it is industrially required to improve the catalyst activity as much as possible. Therefore, various studies have been made on changing the preparation conditions of the catalyst. For example, when the Ziegler-Natta type catalyst is a three-component catalyst, by changing the addition order of the co-catalyst, such as an organoaluminum compound, or by heating and aging the catalyst,
It is known that catalytic activity can be increased to some extent. However, sufficient catalytic activity has not yet been obtained.

[0003]

SUMMARY OF THE INVENTION The present invention relates to a process for producing a linear α-olefin by oligomerization of ethylene using a Ziegler-Natta type catalyst. An object is to provide a method that can be manufactured well.

[0004]

Means for Solving the Problems The present inventors have made intensive studies in view of the above-mentioned problems, and as a result, have found that the addition of a hetero compound having a large electron density of a hetero atom as a catalyst component to a Ziegler-Natta type catalyst allows the catalyst activity to be increased. Was found to be significantly improved. Furthermore, it has been found that by selecting an optimal addition amount of the hetero compound, the catalyst activity can be improved and the by-product of the polymer can be suppressed. The present invention has been completed based on such findings. That is, in the present invention, when a linear α-olefin is produced by oligomerization of ethylene using a Ziegler-Natta type catalyst, the electron density of a hetero atom calculated by the molecular orbital calculation PM3 method as the Ziegler-Natta type catalyst is used. Of a linear α-olefin, characterized in that a hetero compound in the range of 5.8 to 6.5 is added in an amount of 0.05 to 1 mole per mole of the organometallic compound as a cocatalyst. It is intended to provide a manufacturing method.

[0005]

DESCRIPTION OF THE PREFERRED EMBODIMENTS In the method of the present invention, as described above, the Ziegler-Natta type catalyst has a heteroatom electron density calculated by a molecular orbital method of 5.8 to 6.5, preferably 6. Hetero compounds ranging from 0 to 6.3 are added. In the present invention, the electron density of the hetero atom specifically uses a value calculated by the molecular orbital calculation PM3 method. Examples of the hetero compound that can be used include cyclic ethers such as tetrahydrofuran, furan, 2-methyltetrahydrofuran and dibenzofuran, cyclic thioethers such as tetrahydrothiophene, aliphatic ethers such as butyl ethyl ether and ethyl ether, diethyl disulfide and the like. And aliphatic alcohols such as ethyl alcohol and methyl alcohol. Of these, furan, tetrahydrofuran and tetrahydrothiophene are particularly preferably used. These hetero compounds can be used alone or in combination of two or more.

The amount of the hetero compound added to the catalyst varies depending on the electron density of the hetero atom, but is 0.05 to 1 mole, preferably 0.1 mole, per mole of the promoter such as organoaluminum. It is preferably ~ 0.8 times the mole. If the amount is less than 0.05 mole, the effect is not sufficiently exhibited. Further, the above-mentioned hetero compound can be added at any stage during or after the preparation of the catalyst, and excellent effects can be obtained without any particular limitation. For example, it may be added in advance to an organic metal compound such as organoaluminum which is a cocatalyst in the presence of a solvent, or may be added after the preparation of the catalyst. It can also be added directly to the reactor.

When the hetero compound is added to a cocatalyst or a catalyst comprising an organometallic compound such as organoaluminum, the heterocompound coordinates to the organometallic compound, lowers the Lewis acidity of the organometallic compound, and increases the catalytic activity. It is thought that it increases. The preparation of the Ziegler-Natta type catalyst can be performed in an organic solvent. The organic solvent which can be used is not particularly limited, but non-reactive solvents, for example, naphthenic compounds such as cyclohexane and ethylcyclohexane, paraffinic compounds such as pentane, heptane and octane, and halogenated aromatic compounds such as chlorobenzene Group compounds and the like are preferred.

It is preferable to add all the catalyst components and then heat them in a solvent at 40 ° C. or higher, preferably 50 to 80 ° C. for 30 minutes or longer, from the viewpoint of improving the activity. For example, ZrCl ₄ - ethyl aluminum sesquichloride (hereinafter, sometimes abbreviated as EASC.) - triethylaluminum when (. Hereinafter, may be abbreviated as TEA) preparing catalysts, first T to ZrCl ₄
After EA was added, EASC was added, and the mixture was heated to 70 ° C under a solvent.
By heating for 30 minutes or more, a catalyst with higher activity can be obtained. The oligomerization of ethylene can be carried out efficiently by bringing the catalyst solution prepared as described above into contact with ethylene at a predetermined reaction temperature and a predetermined reaction pressure in the presence of a non-reactive solvent.

[0009] The polymerization reaction of ethylene is usually from 100 to 1
At a temperature of 30 ° C, 30 to 70 kg / cm ² · G (2.94
It is performed under a pressure of 〜6.86 MPa). The reaction time depends on the temperature and pressure, but is usually from 10 minutes to
About 60 minutes is enough. In addition, all operations from the preparation of the catalyst to the end of the polymerization reaction are preferably performed with exclusion of air and moisture, and particularly preferably performed in an atmosphere of an inert gas such as nitrogen or argon. In the production method of the present invention, ethylene is used as a raw material, and the obtained linear α-olefin has 4 or more carbon atoms, especially 4 to 4 carbon atoms.
18 low-polymerized α-olefins, which are produced as a mixture thereof. In the present invention, the reaction product solution obtained by polymerizing ethylene can be subjected to, if necessary, recovery of unreacted α-olefin, deactivation of the catalyst, demineralization treatment and the like.

[0010]

Next, the present invention will be described more specifically based on examples, but the present invention is not limited to these examples. Example 1 (1) Preparation of catalyst Under an argon atmosphere, 25 mmol of anhydrous zirconium tetrachloride and 250 ml of dried cyclohexane were introduced into a flask with an internal volume of 500 ml and stirred for 10 minutes. To this, triethylaluminum (TEA) 38.
After adding 9 mmol and stirring for about 10 minutes, 136.1 mmol of ethyl aluminum sesquichloride (EASC) [molar ratio of (EASC + TEA) / ZrCl ₄ =
7, EASC / TEA molar ratio = 3.5)]
The complex was formed with stirring at 70 ° C. for 1 hour. The catalyst solution turned grayish green due to complex formation. This catalyst
As a third component, tetrahydrofuran (THF) was added in a molar amount of 0.35 times that of organoaluminum (EASC + TEA), followed by stirring for 30 minutes.

(2) Oligomerization of ethylene In a 1-liter autoclave equipped with a stirrer, 250 ml of cyclohexane dried under a dry argon atmosphere and a predetermined amount of undecane as an internal standard substance were added.
The temperature was raised to ° C. When the temperature reached 130 ° C., the above prepared catalyst (ZrCl ₄ : 0.08 mmol,
EASC: 0.436 mmol, TEA: 0.124 mmol), and at the same time, the raw material ethylene was poured in at a stretch, and the pressure was raised to the reaction pressure (6.5 MPa). Thereafter, the reaction was performed for 1 hour. During this time, ethylene was continuously charged to keep the reaction pressure constant. After the reaction for 1 hour, a 1N aqueous solution of sodium hydroxide was injected into the autoclave to completely deactivate the catalyst.

Since light components such as C4 are inevitably loss to some extent in the experimental operation, Schulz is calculated from the amount of the undecane-based C8-C30 fraction of the internal standard.
-The C4 and C6 production amounts were determined using the Flory distribution, and the yield was determined. The product liquid was filtered with a 5A filter paper, and the solid matter in the filtered filter paper was dried at 140 ° C. for 24 hours, and the weight was taken as the polymer content.

Example 2 The procedure of Example 1 was repeated, except that butyl ethyl ether was added instead of tetrahydrofuran. The results are shown in Table 1. Example 3 The same operation as in Example 1 was carried out except that 2-methyl-tetrahydrofuran was added instead of tetrahydrofuran. The results are shown in Table 1. Example 4 The same operation as in Example 1 was performed, except that 2-methyl-tetrahydrofuran was added instead of tetrahydrofuran in a molar amount 0.7 times the amount of the organoaluminum. The results are shown in Table 1.

Example 5 The procedure of Example 1 was repeated, except that furan was used as the third component instead of tetrahydrofuran in a molar amount 0.7 times the amount of organoaluminum. The results are shown in Table 1. Example 6 The same operation as in Example 1 was performed, except that dibenzofuran was added in a 0.7-fold molar amount to the organoaluminum instead of tetrahydrofuran. The results are shown in Table 1. Example 7 The same operation as in Example 1 was carried out except that tetrahydrothiophene was added instead of tetrahydrofuran in a molar amount 0.7 times the amount of organoaluminum. The results are shown in Table 1.

Comparative Example 1 Example 1 was repeated except that tetrahydrofuran was not added.
The same operation was performed. The results are shown in Table 1. Comparative Example 2 The same operation as in Example 1 was performed, except that the addition amount of tetrahydrofuran was 1.5 times mol of the organoaluminum. The results are shown in Table 1. Comparative Example 3 The same operation as in Example 1 was performed, except that 2-methyl-tetrahydrofuran was added instead of tetrahydrofuran in a molar amount of 1.5 times the amount of organoaluminum. The results are shown in Table 1. In the table, THF is tetrahydrofuran, B
EE means butyl ethyl ether, 2Me-THF means 2-methyl-tetrahydrofuran, and THT means tetrahydrothiophene.

[0016]

[Table 1]

[0017]

[Table 2]

[0018]

[Table 3] In the above Examples and Comparative Examples, the electron density of the hetero atom is a value calculated using the PM3 method of MOPAC97 for molecular orbital calculation. The catalytic activity was determined as follows. The value obtained by dividing the weight (g) of the yield (α-olefin) corrected from the Schulz-Flory distribution formula by the weight of the catalyst (ZrCl ₄ ) charged into the autoclave was defined as the catalytic activity (g / g-ZrCl ₄ / h). .

[0019]

According to the present invention, the catalytic activity of the Ziegler-Natta type catalyst can be improved and the by-product of the polymer can be suppressed, and the linear α-olefin can be efficiently produced by a simple operation. it can.

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Claims (4)

[Claims] In producing a linear α-olefin by oligomerization of ethylene using a Ziegler-Natta type catalyst, the electron density of a hetero atom calculated by a molecular orbital calculation PM3 method as a Ziegler-Natta type catalyst is determined. 5. Production of a linear α-olefin, characterized in that a hetero compound in the range of 5.8 to 6.5 is added in an amount of 0.05 to 1 times the mol of an organometallic compound as a co-catalyst. Method. 2. The linear α-olefin according to claim 1, wherein the hetero compound is at least one member selected from cyclic ethers, cyclic thioethers, aliphatic ethers, sulfide compounds and aliphatic alcohols. Manufacturing method. 3. The method according to claim 1, wherein the hetero compound is added in advance to the organometallic compound as a promoter.
3. The method for producing a linear α-olefin according to 1.). 4. The method for producing a linear α-olefin according to claim 1, wherein the hetero compound is added after the preparation of the catalyst.