JPH0827037A - Method for dimerizing lower olefin - Google Patents

Abstract

PURPOSE:To provide a method for dimerizing a lower olefin in an extremely high selectivity of a dimer almost without forming a high-boiling compound. CONSTITUTION:This method for dimerizing a lower olefin uses a catalyst comprising a compound containing (1) at least one of a salt and a complex compound of a transition metal belonging to the platinum group of the periodic table, (2) at least one of a trialkylaluminum, a halogenated dialkylaluminum and a dihalogenated alkylaluminum compounds and (3) a poly(alkylaluminoxane) of the formula, [-Al(R)-O-]n (R is an alkyl; (n) is an integer of 3-200) as structural units.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for dimerizing a lower olefin which can be easily obtained in a large amount in the petrochemical industry into a higher olefin. The obtained higher olefin is an important raw material such as a plasticizer.

[0002]

2. Description of the Related Art A technique based on Ziegler's nickel effect is well known for dimerization of lower olefins. For example, a method of simultaneously using nickel fatty acid salt and ethyl aluminum dichloride as a catalyst is
It is disclosed in JP-A-54-92091 and JP-A-54-15751. According to these methods, an olefin can be dimerized under mild conditions, but a high-boiling-point by-product is simultaneously produced in addition to the target product, and the dimer selectivity is poor.

Although the above-mentioned dimerization reaction is carried out in a homogeneous system,
For example, those using metal oxides such as zirconia and titania as catalysts (JP-A-5-213781), or
A heterogeneous dimerization reaction such as a catalyst using a Ziegler catalyst supported on an acidic metal oxide (JP-A-62-142125) is also disclosed. Although these dimerization reactions have the advantage of easy catalyst separation, it is difficult to prepare the catalyst, and by selecting a target dimer such as a by-product of a paraffin compound that has a boiling point very close to the target product and is difficult to separate. There are problems such as low rates.

Japanese Unexamined Patent Publication (Kokai) No. 61-145126 discloses a dimerization reaction of a lower olefin with a catalyst in which a noble metal such as palladium or ruthenium and a special acid are combined. However, since it is a reaction under strongly acidic conditions, it has the drawback of being highly corrosive to the equipment.
It is also unsatisfactory in terms of target dimer selectivity.

A catalyst obtained by adding various additives to a Ziegler type catalyst is used for the purpose of increasing the selectivity of the dimer. JP-A-55-136236 and JP-A-59-210034 disclose a dimerization reaction using a catalyst to which a polyol is added. According to these dimerization reactions, a dimer can be obtained with higher selectivity than the dimerization reaction using a conventional Ziegler type catalyst, but there is still room for improvement considering the by-product rate of high boiling point compounds. There is.

Further, JP-A-57-167932 discloses a phosphorus compound and water, JP-A-57-169433 discloses a phosphorus compound and dialuminoxane, and JP-A1-221335 discloses a phosphorus compound and active hydrogen. A dimerization reaction using a compound-added catalyst is disclosed. However, this method is also insufficient in terms of selectivity of the target, and this method is applied only to α-olefins,
Considering that the industrial availability of pure α-olefin is not easy, it is unsuitable industrially.

Japanese Unexamined Patent Publication (Kokai) No. 4-41440 discloses an olefin dimerization reaction using a catalyst in which a quaternary phosphonium salt is added to a Ziegler type catalyst. This is still inadequate. A method for dimerization of olefins using methylaluminoxane, which is one of compounds having poly (alkylaluminoxane) as a structural unit, is also known. For example, JP-A-2-174676 discloses a combination of a zirconium complex and methylaluminoxane as a dimerization reaction of a higher olefin. However, the catalyst system is known to have excellent performance as a catalyst for polymerization of lower olefins such as ethylene, propylene and butene (“Catalyst”, Vol. 33, No. 8, p. 536, 19
1991), but is not suitable for dimerization of lower olefins.

As disclosed in Japanese Patent Laid-Open No. 62-202595,
A catalyst system combining a zirconium complex and methylaluminoxane is disclosed. This method is applied only to α-olefins and has many industrial restrictions.
From the viewpoint of the selectivity of the reaction, the dimerization reaction of octene illustrated has a high dimer selectivity, but in the dimerization reaction of propylene, in addition to the dimer, a trimer or more Since a large amount of high boiling point compounds are produced, it cannot be said to be an excellent method for dimerizing lower olefins with high selectivity.

[0009]

SUMMARY OF THE INVENTION An object of the present invention is to provide a method capable of dimerizing a lower olefin with almost no formation of high boiling point compounds and with a very high dimer selectivity. It is in.

[0010]

The present invention provides (1) at least one of salts or complex compounds of transition metals belonging to the platinum group in the periodic table, (2) trialkylaluminum,
At least one of a dialkylaluminum halide or a dialkylaluminum halide compound,
And a poly (3) represented by the formula (I) [-Al (R) -O-] _n (I) (wherein R represents alkyl and n represents an integer of 3 to 200). Alkylaluminoxane)
The present invention relates to a method for dimerizing a lower olefin, which comprises using a catalyst composed of a compound containing as a structural unit.

The present invention will be described in detail below. The lower olefin is a mono-olefin having 2 to 7 carbon atoms and represents, for example, ethylene, propylene, 1-butene, isobutene, 2-butene, 1-hexene, 1-heptene and the like. Among them, in the petrochemical industry, a large amount can be obtained from a thermal cracking process of petroleum or a fluidized bed catalytic cracking process, and
The dimerization product has a great significance for efficiently dimerizing a C4 monoolefin mixture, that is, a butene fraction, which is in great demand as a raw material for a plasticizer. Included in the butene fraction are 1-butene, cis and trans 2-butene, and isobutene. The present invention also includes dimerization using these olefins alone, or co-dimerization using a mixture of any two or more kinds of these olefins at any ratio.

The salt or complex compound of a transition metal belonging to the platinum group in the periodic table used in the present invention is a salt or complex compound of platinum, palladium, or nickel.
It is used in a molar ratio of 10 ⁻⁷ to 10 ⁻³ , preferably 10 ⁻⁵ to 10 ⁻³ , and more preferably 10 ⁻⁵ to 10 ⁻⁴ with respect to the raw material olefin. These compounds may be used alone or as a mixture of two or more kinds. Further, these compounds can also be used after being dissolved in an aprotic solvent such as toluene, hexane, tetrahydrofuran, dimethoxyethane, dimethylformamide, or the like.

Platinum salts include platinum chloride, platinum bromide,
Examples include platinum iodide, platinum acetate, platinum 2-ethylhexanoate, platinum naphthenate, platinum nitrate and the like. Platinum complex compounds include platinum chloride or platinum bromide such as acetonitrile, triphenylphosphine, tributylphosphine, 1,2-bisdiphenylphosphinoethane, 1,4-bisdiphenylphosphinobutane, and other dicyclopentadiene complexes. Examples include enylplatinum and platinum acetylacetonate.

Examples of the salt of palladium include palladium chloride, palladium bromide, palladium iodide, palladium acetate, palladium 2-ethylhexanoate, palladium naphthenate, palladium nitrate and the like. Palladium complex compounds include complexes of palladium chloride or palladium bromide such as acetonitrile, triphenylphosphine, tributylphosphine, 1,2-bisdiphenylphosphinoethane, 1,4-bisdiphenylphosphinobutane, and dicyclopentadiene. Examples thereof include enyl palladium and palladium acetylacetonate.

Examples of the nickel salt include nickel chloride, nickel bromide, nickel iodide, nickel acetate, nickel 2-ethylhexanoate, nickel naphthenate, nickel nitrate and the like. Complex compounds of nickel include nickel chloride or nickel bromide such as acetonitrile, triphenylphosphine, tributylphosphine, 1,2-bisdiphenylphosphinoethane, 1,4-bisdiphenylphosphinobutane, and dicyclopentadiene complex. Examples thereof include enyl nickel and nickel acetylacetonate.

In the trialkylaluminum, halogenated dialkylaluminum or dihalogenated alkylaluminum compound, alkyl has 1 to 6 carbon atoms,
For example, it represents methyl, ethyl, propyl, isopropyl, butyl, isobutyl, pentyl, hexyl and the like. Moreover, halogen represents chlorine, bromine, or the like. Examples of trialkylaluminum compounds include trimethylaluminum, triethylaluminum, triisobutylaluminum, trihexylaluminum and the like. Examples of the halogenated dialkylaluminum compound include dimethylaluminum chloride, diethylaluminum chloride, dipropylaluminum chloride,
Examples thereof include diisobutylaluminum chloride, dihexylaluminum chloride, dimethylaluminum bromide, diethylaluminium bromide and diisobutylaluminum bromide. Examples of the dihalogenated alkyl aluminum compound include methyl aluminum dichloride, ethyl aluminum dichloride, propyl aluminum dichloride, isobutyl aluminum dichloride, hexyl aluminum dichloride, methyl aluminum dibromide, ethyl aluminum dibromide, isobutyl aluminum dibromide and the like. These compounds may be used alone or in a mixture.

These metal compounds may be supplied as a solution of an aprotic solvent such as hexane, heptane, benzene, toluene, xylene and tetrahydrofuran, but in that case, the solution may be used as it is. Absent. The trialkylaluminum, halogenated dialkylaluminum or dihalogenated alkylaluminum compound used in the present invention is in a molar ratio of 10 ⁻⁶ to 10 ⁻¹ , preferably 10 ⁻⁵ to 10 to a raw material olefin. 10 ^-1 , more preferably 5 x 10 ^-5 ~
Used in the range of 10 ^-2 .

The alkyl in the compound having the poly (alkylaluminoxane) represented by the formula (I) as a structural unit has the same meaning as described above. This compound is known to have a chain or cyclic structure, but any of them can be used. In the case of a chain compound, the terminal group is alkyl as defined above. There may be more than one type of alkyl in a chain or ring. It is also included in the present invention to use those in which these compounds having various forms such as chain and ring are present in association with each other. In addition, these compounds are
They may be used alone or in combination of two or more. A typical example of this compound is methylaluminoxane.

The compound having this poly (alkylaluminoxane) as a structural unit is generally prepared by treating trialkylaluminum with 1 equivalent or more of water based on trialkylaluminum in the presence of a metal salt such as aluminum. (JP-A-59-95292), a method in which a trialkylaluminum is treated with 0.5 equivalent of water with respect to an aluminum atom in the coexistence of a tetraalkyldialuminoxane (JP-A-4-46906). . The obtained product is generally a mixture of oligomers having a distribution in the degree of polymerization, and usually chain-like ones and cyclic ones are mixed. Depending on the preparation method, there may be a small amount of trialkylaluminum remaining, but these may be used as they are.

The compound having this poly (alkylaluminoxane) as a structural unit is generally supplied as a solution of an aprotic solvent such as hexane, heptane, benzene, toluene, xylene, tetrahydrofuran, etc. You may use. For the purpose of preparing a compound having a poly (alkylaluminoxane) as a structural unit in the reaction system, a metal salt such as aluminum, trialkylaluminum, and 1 equivalent or more of water based on trialkylaluminum, or tetraalkyldialuminoxane It is also included in the present invention that trialkylaluminum and 0.5 equivalent of water based on aluminum atom are used instead of the compound having poly (alkylaluminoxane) as a structural unit.

The compound having this poly (alkylaluminoxane) as a structural unit has a molar ratio of aluminum atoms of 10 ⁻⁶ to 10 ^{−1 with} respect to the raw material butene.
Preferably, 10 ⁻⁵ to 10 ⁻¹ , more preferably 5 ×
It is used in the range of 10 ⁻⁵ to 10 ⁻² . Furthermore, the total number of moles of aluminum atoms of a compound having a poly (alkylaluminoxane) as a structural unit and a trialkylaluminum, a dialkylaluminum halide or an alkylaluminum dihalide compound is a transition metal belonging to the platinum group in the periodic table. It is more preferable to use 2 to 100 with respect to the number of moles of the salt or complex compound.

The reaction temperature is in the range of 0 to 150 ° C, preferably 20 to 100 ° C. A higher reaction temperature generally gives a higher reaction rate, but on the other hand, the reaction pressure becomes higher and the selectivity of the dimer decreases, so it is not preferable that the reaction temperature be too high. The reaction pressure is determined by the composition and temperature inside the reactor and is not particularly limited, but is usually in the range of 0 to 30 atm, preferably 1 to 10 atm. When the reaction form is a batch system, the proportion of the lower olefin as a raw material decreases with the progress of the reaction, and the proportion of the dimer having a higher boiling point increases, so that the reaction pressure decreases with time. It is normal. The reaction time is 30 minutes to 20 hours, preferably 1 to 1
0 hours. The longer the reaction time, the higher the conversion rate of the lower olefin as a raw material, but the selectivity of the dimer tends to decrease slightly.

After completion of the reaction, the active catalyst is deactivated by adding an alkaline aqueous solution such as sodium hydroxide, and the separated oil layer is separated from the separated oil layer by a conventional organic synthetic chemical means such as distillation.
The desired dimer can be isolated using various types of chromatography and the like. In carrying out the present invention,
Inert compounds such as methane, ethane, propane, butane, isobutane, hexane, heptane, toluene and xylene may be present in the dimerization reaction system. Although it is essentially unnecessary to use a solvent, it is also possible to use the above-mentioned compounds as a solvent.

The present invention will be described in more detail with reference to Examples and Comparative Examples below.

[0025]

EXAMPLES The identification of products and by-products was carried out by gas chromatography in comparison with authentic samples.
The products and by-products were quantified by gas chromatography using the internal standard method. GC-14A (Shimadzu) is used for gas chromatography and PE is used for the column.
A glass packed column with G-HT packing was used. The high boiling point product was quantified by gel permeation chromatography (GPC). GPC used HLC-8020 (made by Tosoh Corporation).

Example 1 A nickel acetylacetonate (toluene solution having a nickel concentration of 2.5 wt%, 62.3 mg), mixed butenes (20.0 g, composition: : 15.6wt%, isobutane: 2.7wt%, 1-
Butene: 35.1wt%, 2-butene: 35.5wt%, isobutene:
11.1 wt%) was charged and stirred for 5 minutes. After that, ethyl aluminum dichloride (20 wt% hexane solution, 0.5 mL, purchased from Japan Alkyl Aluminum Co., Ltd., abbreviated as EADC below),
Then, as a compound having a poly (alkylaluminoxane) skeleton, methylaluminoxane (6 wt% toluene solution of aluminum atoms, type 3A, 0.1 mL, purchased from Tosoh Akzo Co., Ltd., hereinafter abbreviated as MMAO) was added. The inside of the reactor was heated to 45 ° C. using an oil bath and reacted for 2 hours while stirring.

The pressure in the reactor was 3.7 atm (gauge pressure) at the beginning of the reaction, but it decreased to 2.7 atm after 2 hours. After the reaction was completed, the pressure-resistant reactor was depressurized, and the gas components generated at that time were collected using a dry ice-acetone trap, and quantitative analysis was performed using gas chromatography. It was butene, and 13.5 g was obtained. The depressurized pressure-resistant reactor was opened, the internal solution was transferred to a beaker, and a 0.5 N sodium hydroxide aqueous solution (20 mL) was added to deactivate the catalyst. When the separated oil layer was subjected to quantitative analysis using gas chromatography, octene as a dimerization product was found to be
It turned out that 5.7 g was generated. Butene conversion rate is
38%, octene selectivity 88%, octene: dodecene (
The ratio of trimer: hexadecene (tetramer) is 94: 6: 0. In addition, from the GPC analysis, the selectivity of the polymer component having 20 or more carbon atoms as a by-product was 3%.

Examples 2 to 6 Table 2 shows the results of the dimerization reaction of mixed butenes carried out in the same manner as in Example 1 under the reaction conditions shown in Table 1.

[0029]

[Table 1]

[0030]

[Table 2]

Comparative Examples 1 to 3 Under the reaction conditions shown in Table 3, the dimerization reaction of mixed butenes was carried out in the same manner as in Example 1 except that MMAO was not used. The reaction conditions and results are shown in Table 4.

[0032]

[Table 3]

[0033]

[Table 4]

[0034]

Industrial Applicability According to the present invention, it is possible to provide a method for dimerizing a lower olefin with almost no formation of a high boiling point compound and with a very high dimer selectivity.

Claims (2)

[Claims] 1. (1) At least one of salts or complex compounds of transition metals belonging to the platinum group in the periodic table, (2)
At least one of a trialkylaluminum, a dialkylaluminum halide or a dihalogenated alkylaluminum compound, and (3) formula (I) [-Al (R) -O-] _n (I) (wherein R is Poly (alkylaluminoxane) represented by alkyl and n represents an integer of 3 to 200.
A method for dimerizing a lower olefin, which comprises using a catalyst comprising a compound containing as a structural unit. 2. The method according to claim 1, wherein the transition metal belonging to the platinum group in the periodic table is nickel.