JP3486212B2 - Method for producing low α-olefin polymer - 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 producing an α-olefin low polymer, and more specifically, a portion of the α-olefin low polymer obtained by a low polymerization reaction is subjected to a hydrogenation treatment. The present invention relates to a method for producing an industrially advantageous α-olefin low polymer by reducing the solvent cost by converting the saturated hydrocarbon into a saturated hydrocarbon and circulating the saturated hydrocarbon in the polymerization reaction system.

[0002]

2. Description of the Related Art Conventionally, as a method for low polymerization of α-olefin such as ethylene, there has been known a method of using a chromium-based catalyst comprising a combination of a specific chromium compound and a specific organoaluminum compound. For example, Japanese Patent Publication No.
8707 describes a method for obtaining 1-hexene from ethylene by a catalyst system composed of a transition metal compound (M) of Group VIA containing chromium and having a general formula MXn and polyhydrocarbyl aluminum oxide (X). ing.

Further, in JP-A-3-128904, α-olefin is trimerized by using a catalyst obtained by previously reacting a chromium-containing compound having a chromium-pyrrolyl bond with a metal alkyl or Lewis acid. How to do is described.

[0004]

However, in the method described in Japanese Patent Publication No. 43-18707, the amount of polyethylene by-produced at the same time as 1-hexene is large and the amount of polyethylene by-produced is small. There is a problem that the catalytic activity is lowered. In addition, JP-A-3-12890
The method described in Japanese Patent No. 4 has a problem that although the amount of by-produced polymers such as polyethylene is small, the catalytic activity is not sufficient.

The present invention has been made in view of the above circumstances, and an object thereof is to be able to produce an α-olefin low polymer such as 1-hexene with a high yield and a high selectivity, and to use a solvent. An object of the present invention is to provide an industrially advantageous method for producing an α-olefin low polymer, which is cost-effective.

[0006]

Means for Solving the Problems The inventors of the present invention have conducted extensive studies to achieve the above-mentioned object, and as a result, by using a specific chromium-based catalyst and a solvent and carrying out polymerization under specific conditions, An α-olefin low polymer can be produced in a high yield and a high selectivity, and a part of the obtained α-olefin low polymer is hydrogenated to be converted into a saturated hydrocarbon, It was found that the cost of the solvent can be reduced by circulating the hydrocarbon in the polymerization reaction system.

The present invention has been completed based on the above findings, and the gist thereof is, in a method for producing an α-olefin low polymer using a chromium-based catalyst, at least a chromium compound as a chromium-based catalyst. After a low polymerization of α-olefin is carried out in a saturated hydrocarbon solvent by using a catalyst system consisting of a combination of an alkyl aluminum compound with an amine or a metal amide and an alkylaluminum compound, and then the by-produced polymer is separated and removed from the obtained reaction solution. A part of the obtained α-olefin low polymer is hydrogenated to be converted into saturated hydrocarbon, and the saturated hydrocarbon is circulated to the polymerization reaction system.
-A method for producing olefin low polymers.

The present invention will be described in detail below. In the present invention, in order to produce α-olefin low-polymerization objects with high yield and high selectivity, at least as a chromium-based catalyst,
A catalyst system consisting of a combination of a chromium compound and an amine or a metal amide and an alkylaluminum compound is used.
Then, in a preferred embodiment of the present invention, as described below, the α-olefin and the chromium-based catalyst are brought into contact with each other in such a manner that the chromium compound and the alkylaluminum compound do not come into contact with each other in advance.

The chromium compound used in the present invention is represented by the general formula CrXn. However, in the general formula, X represents an arbitrary organic group or inorganic group or a negative atom, n represents an integer of 1 to 6, and when n is 2 or more, X may be the same or different from each other. Good. The valence of chromium is 0 to 6, and n in the above formula is preferably 2 or more.

Examples of the organic group include various groups having usually 1 to 30 carbon atoms. Specific examples thereof include a hydrocarbon group, a carbonyl group, an alkoxy group, a carboxyl group, a β-diketonate group, a β-ketocarboxyl group, a β-ketoester group and an amide group. Examples of the hydrocarbon group include an alkyl group, a cycloalkyl group, an aryl group, an alkylaryl group and an aralkyl group. Examples of the inorganic group include a chromium salt-forming group such as a nitrate group and a sulfate group, and examples of the negative atom include oxygen and halogen.

A preferred chromium compound is an alkoxy salt of chromium, a carboxyl salt, a β-diketonate salt, a salt of β-ketoester with an anion, or a chromium halide, and specifically, chromium (IV) tert-butoxide. , Chromium (III) acetylacetonate, chromium (III)
Trifluoroacetylacetonate, chromium (III) Hexafluoroacetylacetonate, chromium (III) (2
2,6,6-tetramethyl-3,5-heptanedionate), Cr (PhCOCHCOPh) ₃ (provided that P is
h represents a phenyl group. ), Chromium (II) acetate, chromium (III) acetate, chromium (III) 2-ethylhexanoate, chromium (III) benzoate, chromium (III) naphthenate, Cr (CH ₃ COCHCOOCH ₃ ) ₃ , chromium (III) chloride , Chromium chloride, chromium bromide, chromium bromide, chromium iodide, chromium iodide, chromium fluoride, chromium fluoride and the like.

Further, a complex composed of the above-mentioned chromium compound and an electron donor can also be preferably used. The electron donor is selected from compounds containing nitrogen, oxygen, phosphorus or sulfur.

Examples of the nitrogen-containing compound include nitriles, amines, amides, and the like. Specifically, acetonitrile, pyridine, dimethylpyridine, dimethylformamide, N-methylformamide, aniline, nitrobenzene, tetramethylethylenediamine, diethylamine,
Examples include isopropylamine, hexamethyldisilazane, and pyrrolidone.

Examples of oxygen-containing compounds include esters, ethers, ketones, alcohols, aldehydes,
Specific examples include ethyl acetate, methyl acetate, tetrahydrofuran, dioxane, diethyl ether, dimethoxyethane, diglyme, triglyme, acetone, methyl ethyl ketone, methanol, ethanol, acetaldehyde and the like.

Examples of phosphorus-containing compounds include hexamethylphosphamide, hexamethylphosphorus triamide, triethylphosphite, tributylphosphine oxide and triethylphosphine. On the other hand, examples of the sulfur-containing compound include carbon disulfide, dimethyl sulfoxide, tetramethylene sulfone, thiophene and dimethyl sulfide.

Therefore, as an example of a complex composed of a chromium compound and an electron donor, a chromium halide ether complex,
Ester complex, ketone complex, aldehyde complex, alcohol complex, amine complex, nitrile complex, phosphine complex,
Examples thereof include thioether complexes. Specifically, Cr
Cl ₃ / 3THF, CrCl ₃ / 3dioxane, C
_{rCl 3 · (CH 3 CO 2} n-C 4 H 9), CrCl 3
_{· (CH 3 CO 2 C 2} H 5), CrCl 3 · 3 (i-C
₃ H ₇ OH), CrCl ₃ · 3 [CH ₃ (CH ₂ ) ₃ C
H (C ₂ H ₅ ) CH ₂ OH], CrCl ₃ / 3pyri
_{dine, CrCl 3 · 2 (i} -C 3 H 7 NH 2),
[CrCl ₃ · 3CH ₃ CN] · CH ₃ CN, CrCl
_{3 · 3PPh 3, CrCl 2 ·} 2THF, CrCl 2 ·
2pyridine, CrCl ₂ · 2 [(C ₂ H ₅ ) ₂ N
H], CrCl ₂ · 2CH ₃ CN, CrCl ₂ · 2 [P
(CH ₃ ) ₂ Ph] and the like.

As the chromium compound, a compound soluble in a hydrocarbon solvent is preferable, and a β-diketonate salt of chromium,
Carboxylates, salts with anions of β-ketoesters, β
-Ketocarboxylic acid salts, amide complexes, carbonyl complexes, carbene complexes, various cyclopentadienyl complexes, alkyl complexes, phenyl complexes and the like. Examples of various carbonyl complexes of chromium, carbene complexes, cyclopentadienyl complexes, alkyl complexes, and phenyl complexes include Cr (CO) ₆ , (C ₆ H ₆ ) Cr (CO) ₃ ,
(CO) ₅ Cr (= CCH ₃ (OCH ₃ )), (CO)
₅ Cr (= CC ₆ H ₅ (OCH ₃ )), CpCrCl ₂
(Where Cp represents a cyclopentadienyl group), (
Cp * CrClCH ₃ ) ₂ (where Cp * represents a pentamethylcyclopentadienyl group), (CH ₃ ) ₂ CrC
1 and the like are exemplified.

The chromium compound can be used by supporting it on a carrier such as an inorganic oxide, but it is preferable to use it in combination with other catalyst components without supporting it on the carrier. That is, according to the preferred embodiment of the present invention, when the chromium-based catalyst is used in the specific contact mode described later, high catalytic activity can be obtained without supporting the chromium compound on the carrier. When the chromium compound is used without being loaded on the carrier, the loading on the carrier which involves complicated operations can be omitted, and the total amount of the catalyst used (the total amount of the carrier and the catalyst component) is increased by the use of the carrier. It is possible to avoid the problem.

The amine used in the present invention is a primary or secondary amine.
It is a class amine. As the primary amine, ammonia,
Ethylamine, isopropylamine, cyclohexylamine, benzylamine, aniline, naphthylamine, etc. are exemplified, and secondary amines include diethylamine, diisopropylamine, dicyclohexylamine, dibenzylamine, 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 and pyrrolidine.

The metal amide used in the present invention is a metal amide derived from a primary or secondary amine, specifically, a primary or secondary amine and a group IA or IIA,
An amide obtained by reaction with a metal selected from Group IIIB and Group IVB. Specific examples of such metal amides include lithium amide, sodium ethylamide, calcium diethylamide, lithium diisopropylamide, potassium benzylamide, sodium bis (trimethylsilyl) amide, lithium indolide, sodium pyrrolide, lithium pyrrolide and potassium. Examples thereof include pyrrolide, potassium pyrrolidide, aluminum diethylpyrrolide, ethylaluminum dipyrrolide and aluminum tripyrolide.

In the present invention, a secondary amine, a metal amide derived from a secondary amine, or a mixture thereof is preferably used. Particularly, as the secondary amine, pyrrole, 2,5-dimethylpyrrole, 3,4-dimethylpyrrole, 3,4-dichloropyrrole, 2,3,4,5
-Tetrachloropyrrole, 2-acylpyrrole, and metal amides derived from secondary amines include aluminum pyrrolide, ethylaluminum dipyrrolide, aluminum tripyrolide, sodium pyrrolide, lithium pyrrolide and potassium pyrrolide. It is suitable. Among the pyrrole derivatives, those having a hydrocarbon group on the pyrrole ring are particularly preferable.

In the present invention, an alkylaluminum compound represented by the following general formula (1) is preferably used as the alkylaluminum compound.

Embedded image R ¹ _m Al (OR ² ) _n H _p X _q (1)

In the formula, R ¹ and R ² usually have a carbon number of 1 to
15, preferably 1 to 8 hydrocarbon groups, which may be the same or different from each other, X represents a halogen atom, m is 0 <m ≦ 3, n is 0 ≦ n <3, p Is 0 ≦ p <
3 and q are numbers of 0 ≦ q <3, and
It represents a number that is m + n + p + q = 3.

Examples of the above-mentioned alkylaluminum compound include trialkylaluminum compounds represented by the following general formula (2), halogenated alkylaluminum compounds represented by the general formula (3), and alkoxy groups represented by the general formula (4). Examples thereof include aluminum compounds and alkylaluminum hydride compounds represented by the general formula (5). The meanings of R ¹ , X and R ² in each formula are the same as above.

[0025]

Embedded image R ¹ ₃ Al (2) R ¹ _m AlX _3-m (m is 1.5 ≦ m <3) (3) R ¹ _m Al (OR ² ) _3-m ( m is 0 <m <3, preferably 1.5 ≦ m <3) (4) R ¹ _m AlH _3-m (5) (m is 0 <m <3, preferably 1. 5 ≦ m <3)

Specific examples of the alkylaluminum compound include trimethylaluminum, triethylaluminum, triisobutylaluminum, diethylaluminum monochloride, diethylaluminum ethoxide, diethylaluminum hydride and the like. Among these, trialkylaluminums are particularly preferable in that the amount of polymer by-products is small.

In the present invention, first, low polymerization of α-olefin is carried out in a solvent using a catalyst system consisting of the above catalyst components, and then the by-produced polymer in the reaction solution is separated without melting. The α-olefin low polymer is recovered by removal.

The amount of chromium compound used is usually 0.1 × 10 ^{−3 to 5} g, preferably 1.0, per liter of solvent.
It is in the range of x10 ^{-3 to 2} g. On the other hand, the amount of the alkylaluminum compound used is usually 0.1 mmol or more per 1 g of the chromium compound, but is preferably 5 mmol or more from the viewpoint of catalytic activity and trimer selectivity.
And the upper limit is usually 50 mol. The amount of amine or metal amide used is 1 g of chromium compound,
It is usually 0.001 equivalent or more, preferably 0.005
To 1000 equivalents, and more preferably 0.01 to 100 equivalents.

In the present invention, it is preferable to contact the α-olefin with the chromium-based catalyst in such a manner that the chromium compound and the alkylaluminum compound do not contact with each other in advance. According to such a contact mode, it is possible to selectively carry out the trimerization reaction and obtain 1-hexene from the raw material ethylene in a high yield.

The above-mentioned specific contact mode is specifically as follows.
When the amine is represented by “amine or metal amide”, (1) a method of introducing α-olefin and a chromium compound into a solution containing an amine and an alkylaluminum compound, and (2) α into a solution containing a chromium compound and an amine. -Method of introducing olefin and alkylaluminum compound (3) Method of introducing α-olefin, amine and alkylaluminum compound into a solution containing chromium compound, (4) α-olefin, chromium into solution containing an alkylaluminum compound It can be carried out by a method of introducing a compound and an amine, (5) a method of introducing each of a chromium compound, an amine, an alkylaluminum compound and α-olefin into a reactor simultaneously and independently. And each said solution is normally prepared using a reaction solvent.

In the above description, the phrase "a mode in which the chromium compound and the alkylaluminum compound do not come into contact with each other in advance" means not only at the start of the reaction but also after that, additional α-olefin and the catalyst component are supplied to the reactor. Also means that such a mode is maintained.

The reason why the activity of the low polymerization reaction of α-olefin becomes low when the chromium-based catalyst is used in such a manner that the chromium compound and the alkylaluminum compound are in contact with each other in advance is not clear yet, but it is presumed as follows. To be done.

That is, it is considered that when the chromium compound and the alkylaluminum are brought into contact with each other, the ligand exchange reaction proceeds between the ligand coordinated to the chromium compound and the alkyl group in the alkylaluminum compound. And, the alkyl-chromium compound produced by such a reaction is unstable in itself, unlike the alkyl-chromium compound produced by the usual method. Therefore, alkyl-
The decomposition / reduction reaction of the chromium compound preferentially proceeds, and as a result, inappropriate demetallation is induced in the low polymerization reaction of α-olefin, and the activity of the low polymerization reaction of α-olefin decreases.

In the present invention, as the raw material α-olefin, a substituted or unsubstituted α-olefin having 2 to 30 carbon atoms is used. Specific examples include ethylene, propylene, 1-butene, 1-hexene, 1-octene, 3-methyl-1-butene, 4-methyl-1-pentene and the like. Particularly, ethylene is suitable as the raw material α-olefin, and 1-hexene, which is a trimer of ethylene, can be obtained from ethylene in high yield and high selectivity.

First, in the present invention, low polymerization of α-olefin is carried out in a saturated hydrocarbon solvent. When an unsaturated hydrocarbon such as olefin is used as the solvent instead of the saturated hydrocarbon, the solvent itself is wastefully consumed due to a low polymerization reaction. On the other hand, the saturated hydrocarbon solvent is inactive in the low polymerization reaction, so that the above problems do not occur.

The saturated hydrocarbon solvent is not particularly limited, but is usually a linear or alicyclic saturated hydrocarbon such as propane, butane, pentane, hexane, heptane, octane, cyclohexane, methylcyclohexane and decalin. Is used. From the viewpoint of handleability in consideration of boiling point and the like, a preferred solvent is a straight chain saturated hydrocarbon having 8 or more carbon atoms.

In the present invention, the low polymerization is preferably carried out at a reaction temperature of 70 ° C. or lower. When the reaction temperature exceeds 70 ° C., the by-product polymer becomes a film or dissolves in the solvent, and it becomes difficult to separate the by-product polymer. The reaction temperature is particularly preferably in the range of 0 to 60 ° C. On the other hand, the reaction pressure can be selected from the range of atmospheric pressure to 250 kg / cm ² , but usually 100 kg / cm ² is sufficient. The residence time is usually 1 minute to 20 minutes.
The time is preferably in the range of 0.5 to 6 hours. The reaction system may be a batch system, a semi-batch system or a continuous system, and it is preferable to make hydrogen coexist during the reaction because improvement in catalytic activity and trimer selectivity is recognized.

Next, in the present invention, the by-produced polymer is separated and removed from the obtained reaction solution. That is, the by-product polymer in the reaction solution is separated and removed without melting. Separation and removal of the by-product polymer is carried out by a known solid-liquid separation device,
For example, it is performed by a filter, a centrifuge, or the like.

Then, in the present invention, the obtained α-
A part of the olefin low polymer is hydrogenated to be converted into saturated hydrocarbon, and the saturated hydrocarbon is circulated to the polymerization reaction system.
The α-olefin low polymer is recovered by distillation means for each fraction. Further, the reaction solvent recovered at the same time is circulated to the polymerization reaction system. The fraction of the α-olefin low polymer to be subjected to the hydrogenation treatment is not particularly limited, but is distilled and separated into a fraction having 4 to 6 carbon atoms and a fraction having 8 or more carbon atoms to obtain a fraction having 8 or more carbon atoms. It is preferable to subject the fraction to hydrogenation treatment.

The amount of the α-olefin low polymer to be subjected to the hydrogenation treatment is sufficient for the amount lost in each step of the polymerization reaction, the separation and removal of the by-produced polymer and the distillation. When the α-olefin low polymer having 8 or more carbon atoms is subjected to the hydrogenation treatment according to the above-described preferred embodiment, the amount of the α-olefin low polymer having 8 or more carbon atoms is produced in the polymerization reaction of the present invention. Since the amount is relatively small, if the entire amount is subjected to the hydrogenation reaction, it is possible to obtain an amount of saturated hydrocarbon commensurate with the loss of the reaction solvent.

The hydrogenation treatment of the α-olefin low polymer is carried out in order to convert the α-olefin contained in the low polymer into a saturated hydrocarbon, and the conditions of the hydrogenation treatment are known. Hydrogenation treatment conditions can be adopted. For example, using a platinum-based catalyst supported on γ-alumina,
Reaction temperature 30 to 150 ° C., pressure 10 to 70 kg / cm ²
The α-olefin low polymer is hydrogenated under the conditions of. However, the hydrogenation treatment conditions are not limited to the above conditions.

On the other hand, other low α-olefin polymers, for example, low α-olefin polymers having 4 to 6 carbon atoms, are further purified by distillation and recovered as a highly pure target component. In the present invention, in particular, highly pure 1-hexene can be industrially advantageously produced from ethylene.

[0043]

EXAMPLES The present invention will be described in more detail with reference to Examples and Comparative Examples, but the present invention is not limited to the following Examples as long as the gist thereof is not exceeded.

Example 1 A 2.4 liter autoclave heated and dried in a drier at 150 ° C. was assembled while hot, and then vacuum nitrogen substitution was performed. The autoclave was equipped with a stirrer equipped with a catalyst feed tube equipped with a rupture plate. Octane (n body 90
%, I form 10%) (980 ml), pyrrole (1.24
4 mmol) of octane solution and triethylaluminum (8,000 mmol) of octane solution were charged to the barrel side of the autoclave, while chromium (III) 2-ethylhexanoate (200 mg, 0) was solubilized with octane in the catalyst feed tube. .420 mmol) was charged. The total amount of octane was 1 liter.

First, the autoclave is heated to 40 ° C.,
Next, ethylene was introduced from the catalyst feed pipe at 40 ° C. The rupture plate ruptured due to ethylene pressure, and the chromium compound was introduced into the barrel side of the autoclave to start low polymerization of ethylene. Ethylene was introduced until the total pressure reached 35 Kg / cm ² , then the total pressure was changed to 35 Kg / cm ² , and the temperature was changed to 4
Maintained at 0 ° C. After 1 hour, ethanol was pressed into the autoclave to stop the reaction. After depressurizing the pressure of the autoclave and performing degassing, the by-product polymer (mainly polyethylene) in the reaction solution was separated and removed by a filter to collect the reaction solution. The results of the composition analysis of the α-olefin low polymer in the reaction solution by gas chromatography are shown in Table 1 (Example 1A).

Then, the reaction solution was distilled to obtain an octane fraction,
Separated into fractions having 4 to 6 carbon atoms and fractions having 8 or more carbon atoms,
The fraction having 8 or more carbon atoms was subjected to hydrogenation treatment. The hydrogenation process is
Using a platinum-based catalyst supported on γ-alumina, the reaction temperature was 90 ° C. and the pressure was 40 kg / cm ² . The results of composition analysis of the hydrogenated product by gas chromatography are shown in Table 1 (Example 1A).

Then, the octane fraction and the hydrogenated product were circulated in the polymerization reaction system, and the reaction was repeated under the same conditions. The solvent composition in the reaction is total octane / C
The weight ratio of _10-20 was 98.9 / 1.1. The results of composition analysis of the α-olefin low polymer in the reaction solution and the above hydrogenated product by gas chromatography are shown in Table 1 (Example 1B). In the table, “OCT” of solvent type represents octane, and the unit of catalyst efficiency is g-α-olefin / 1
The unit of g-chromium compound and catalytic activity is g-α-olefin / g-chromium · Hr.

[0048]

[Table 1] ──────────────────────────────────── Example 1A 1B Solvent type (amount: L) OCT (1) OCT / C _10-20 (98.9 / 1.1) (1) Reaction temperature (℃) 60 60 Ethylene pressure (Kg / cm ² ) 35 35 Reaction time (Hr) 1.0 1.0 <Product amount (g) > 107.9 105.1 <composition distribution _{(wt%)> C 4 13.7} 12.0 C 6 total 75.7 75.5 1-hexen content in _{C 6 (wt%) 95.9 95.5} C 8 2.9 3.8 C 10-20 7.3 8.3 C 22-30 0 0 Wax 0 0 <hydrogenate composition distribution> C ₈ 28.0 − C _10-20 72.0 − <PE> 0.4 0.4 <catalytic efficiency> 540 536 <catalytic activity> 5189 5151 ────────────── ───────────────────────

[0049]

INDUSTRIAL APPLICABILITY According to the present invention described above, it is possible to produce an α-olefin low polymer such as 1-hexene with a high yield and a high selectivity, and to reduce the cost of the solvent. A method for producing an advantageous α-olefin low polymer is provided. Therefore, the industrial value of the present invention is remarkable.

─────────────────────────────────────────────────── ─── Continuation of front page (58) Fields surveyed (Int.Cl. ⁷ , DB name) C07C 2/30 C07C 11/02

Claims (3)

(57) [Claims] 1. A method for producing an α-olefin low polymer using a chromium-based catalyst, wherein a catalyst system comprising at least a combination of a chromium compound and an amine or a metal amide and an alkylaluminum compound is used as the chromium-based catalyst, Low polymerization of α-olefin is performed in a saturated hydrocarbon solvent, and then by-produced polymer is separated and removed from the obtained reaction solution, and then a part of the obtained α-olefin low polymer is subjected to hydrogenation treatment. A method for producing an α-olefin low polymer, which comprises converting to saturated hydrocarbon and circulating the saturated hydrocarbon into a polymerization reaction system. 2. A low polymerization of α-olefin is carried out, and then a by-produced polymer is separated and removed from the obtained reaction solution, and then distilled into a fraction having 4 to 6 carbon atoms and a fraction having 8 or more carbon atoms. The method for producing an α-olefin low polymer according to claim 1, wherein the fraction is separated, the fraction having 8 or more carbon atoms is hydrogenated to be converted into a saturated hydrocarbon, and the saturated hydrocarbon is circulated in the polymerization reaction system. 3. The method for producing an α-olefin low polymer according to claim 1, wherein the α-olefin is brought into contact with the chromium-based catalyst in such a manner that the chromium compound and the alkylaluminum compound do not come into contact with each other in advance.