JPH10101724A - Production of oligomer of alpha-olefin - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a process for preparing an oligomer of an α-olefin which is capable of concentrating a polymer as a by-product and a catalyst component and separating them from each other in an oligomerization reactor by oligomerizing an α-olefin in an oligomerization reactor in the presence of a chromium-based polymn. catalyst and a reaction solvent. SOLUTION: A chromium compd. (A), a nitrogen-contg. compd. (B), an alkylaluminum compd. (C), and a halogen-contg. compd. (D) are combined in a component (A)/component (B)/component (C)/component (D) molar ratio of 1:(1 to 50):(1 to 200):(1 to 50) to obtain a chromium-based catalyst. An α-olefin is fed into an oligomerization reactor contg. the above chromium-based catalyst and a reaction solvent, followed by oligomerization under conditions of TΔ105 deg.C [wherein T represents the reaction temp. ( deg.C)] and P>0.5T-15 [wherein P represents reaction pressure (kg/cm<1> )] for 1min to 20hr.

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 particularly, to a method for producing an α-olefin low polymer mainly composed of 1-hexene from ethylene in a high yield. The present invention relates to an industrially advantageous method for producing an α-olefin low polymer which can be produced at a high selectivity.

[0002]

2. Description of the Related Art In recent years, many proposals have been made as industrially advantageous methods for producing low α-olefin polymers.
For example, JP-A-7-118174 and JP-A-7-11817
No. 5, 7-118326, 7-118327,
7-149671, 7-149673, 7-
Nos. 149,674, 7-149,675 and 7-149
Nos. 676 and 7-165815 use at least a chromium-based catalyst comprising a combination of a chromium compound (a), an amine or metal amide (nitrogen-containing compound) (b), and an alkylaluminum compound (c). Various improved inventions have been proposed.

Further, JP-A-8-3216 and JP-A-8-134131 disclose at least a chromium compound (a), an amine or metal amide (nitrogen-containing compound) (b), and an alkylaluminum compound (c). ) And a chromium-based catalyst comprising a combination of a halogen-containing compound (d).

In each of the above proposals, α-olefin and a chromium-based catalyst are brought into contact with each other in such a manner that the chromium compound (a) and the alkylaluminum compound (c) do not come into contact in advance to reduce the low polymerization of α-olefin. It is disclosed that by performing the process, a target α-olefin low polymer (for example, 1-hexene) can be obtained with higher selectivity.

[0005] By any of the above methods,
By-products of the polymer are inevitable, and in particular, in an industrial production method of an α-olefin low polymer, how to separate the by-product polymer is an important issue. The present inventors previously disclosed in Japanese Patent Application No. 7-349702 a method in which a low-polymer of α-olefin was separated from a reaction solution by distillation, and a by-product polymer in the reaction solution was concentrated together with a catalyst component to be separated. Suggested.

Further, the present inventors have disclosed in Japanese Patent Application No. 7-3497.
No. 02 proposed a method for maintaining the by-product polymer and the catalyst component in the reaction liquid in a dispersed state in the process line from the outlet of the reactor to the inlet of the product distillation column as the above-mentioned improved method. As a method of maintaining the by-product polymer in a dispersed state in the reaction solution, a method of maintaining the temperature of the reaction solution at a temperature at which the by-product polymer does not precipitate, a method of causing hydrogen to be present in the gas phase of the reactor to remove the by-product polymer A method for reforming into a granular form is disclosed, and as a method for maintaining a catalyst component in a dispersed state in a reaction solution, a method for solubilizing the catalyst component by adding a specific additive to the reaction solution is disclosed. I have.

In the method of maintaining the temperature of the reaction solution at a temperature at which the by-product polymer does not precipitate, the higher the temperature, the better. However, if the reaction temperature in the reactor is increased, there is a problem that the performance of the chromium catalyst decreases. Thus, as a specific condition of the reactor, a condition of 80 ° C. and 35 kg / cm ² G is adopted, and thereafter, a method of raising the temperature to 100 ° C. is adopted.

[0008]

SUMMARY OF THE INVENTION The present invention has been made in view of such circumstances, and it is an object of the present invention to employ a higher reaction temperature without deteriorating the performance of a chromium catalyst. An industrially advantageous α- which can easily cope with a method of preventing the by-product polymer from being precipitated in the reactor and concentrating and separating the by-product polymer and the catalyst component together.
An object of the present invention is to provide a method for producing an olefin low polymer.

[0009]

Means for Solving the Problems The present inventors have made various studies to achieve the above object, and as a result, if the reaction temperature is increased in a certain relation with the reaction pressure, the high performance of the chromium catalyst will be improved. We have obtained a new finding that it can be maintained.

The present invention has been completed on the basis of the above findings. The gist of the present invention is to provide the following formulas (1) and (2) in a low polymerization reactor in the presence of a chromium-based catalyst and a reaction solvent. A method for producing an α-olefin low polymer, characterized in that α-olefin low polymerization is carried out under satisfactory reaction conditions.

[0011]

T ≧ 105 ° C. (1) P> 0.5T−15 (2) (T is reaction temperature (° C.), P is reaction pressure (kg / cm)
Representing a ² G). )

[0012]

BEST MODE FOR CARRYING OUT THE INVENTION Hereinafter, the present invention will be described in detail.
In the present invention, as the chromium-based catalyst, a catalyst system comprising at least a combination of at least a chromium compound (a), a nitrogen-containing compound (b) and an alkylaluminum compound (c) is used. In a preferred embodiment, the chromium compound (a), the nitrogen-containing compound (b), the alkylaluminum compound (c), and the halogen-containing compound (d)
Is used. The above three-component or four-component chromium-based catalyst is known as described above. In the present invention, these known chromium-based catalysts can be used without any restriction.

Specifically, as the above-mentioned three-component chromium-based catalyst, for example, a chromium-based catalyst composed of each component described in detail in [0008] to [0025] of JP-A-7-118174 is used. Examples of the four-component chromium-based catalyst that can be used include those described in JP-A-8-3216, [0011] to [0028], or JP-A-8-1.
A chromium-based catalyst composed of the components described in detail in JP-A-34131 [0009] to [0041] can be used.

The chromium compound (a) is typically a carboxyl salt of chromium, and specific examples thereof include chromium (II) acetate, chromium (III) acetate, and chromium (III) -2. -Ethylhexanoate, chromium (III) benzoate, chromium (III) naphthenate and the like. Of these, chromium (III) -2-ethylhexanoate is most preferred.

The nitrogen-containing compound (b) is typically a secondary amine, and specific examples thereof include pyrrole, 2,5-dimethylpyrrole, 3,4-dimethylpyrrole, 4-dichloropyrrole, 2,3
4,5-tetrachloropyrrole and 2-acetylpyrrole are exemplified. Of these, 2,5-dimethylpyrrole is most preferred.

The above alkylaluminum compound (c)
Typical examples include trialkylaluminum compounds, and specific examples thereof include trimethylaluminum, triethylaluminum, and triisobutylaluminum. Of these, triethylaluminum is most preferred.

As the above-mentioned halogen-containing compound (d), in particular, straight-chain hydrocarbons having 2 or more carbon atoms and substituted by 3 or more halogen atoms described in JP-A-8-134131 are mentioned. It is suitable. As specific examples thereof, 1,1,1-trichloroethane, 1,1,
2,2-tetrachloroethane, pentachloroethane,
Hexachloroethane and the like can be mentioned.

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

In the present invention, as a reaction solvent, butane, pentane, 3-methylpentane, hexane, heptane, 2-methylhexane, octane, cyclohexane,
A chain or alicyclic saturated hydrocarbon having 1 to 20 carbon atoms, such as methylcyclohexane, 2,2,4-trimethylpentane, decalin, and an aromatic hydrocarbon such as benzene, toluene, xylene, ethylbenzene, mesitylene, and tetralin. Is used. These can be used alone or as a mixed solvent.

As the reaction solvent, α-olefin itself as a reaction raw material or α-olefin other than the main raw material can be used. As the reaction solvent, α-olefin having 4 to 30 carbon atoms is used, and α-olefin which is liquid at normal temperature is particularly preferable.

In particular, the reaction solvent may have 4 to 1 carbon atoms.
A chain saturated hydrocarbon or an alicyclic saturated hydrocarbon of 0 is preferred. By using these solvents, by-products of the polymer can be suppressed, and when an alicyclic hydrocarbon is used, there is an advantage that a high catalytic activity can be obtained.

In the present invention, low polymerization of α-olefin is carried out in the presence of the chromium-based catalyst and the reaction solvent in the reactor. As the reactor, a pipe reactor or a single-stage or multi-stage mixing tank is usually used. The pipe reactor is basically a type of reactor in which a reaction component is introduced from one end of a straight pipe or a coiled or U-shaped curved pipe, and a reaction product is discharged from the other end. The multi-stage mixing tank is basically a type in which the reaction components are introduced into a first tank of a plurality of mixing tanks arranged in series, sequentially moved to a subsequent tank, and a reaction product is discharged from a final tank. Of the reactor.

In the present invention, it is preferable to contact α-olefin with a chromium-based catalyst in such a manner that the chromium compound (a) and the alkylaluminum compound (c) do not come into contact in advance. According to such a specific contact mode, 1-hexene can be obtained in high yield from the raw material ethylene by selectively performing a trimerization reaction. The above specific contact mode is described in, for example, Japanese Patent Application Laid-Open No. 7-118174, [0029]-
[0031] and [002] of JP-A-8-3216.
9] to [0032], and [0045] to [0050] of JP-A-8-134131, some examples of which are as follows.

(1) A method of introducing α-olefin and a chromium-containing compound into a reaction solvent containing a nitrogen-containing compound and an alkylaluminum compound. (2) a nitrogen-containing compound, an alkylaluminum compound,
A method of introducing α-olefin into a reaction solvent containing a halogen-containing compound. (3) A method of introducing α-olefin, a chromium-containing compound and a halogen-containing compound into a reaction solvent containing a nitrogen-containing compound and an alkylaluminum compound.

However, in the present invention, in addition to preparing the catalyst in the reactor according to the above-described contact mode, a low-polymerization reaction may be performed by supplying a separately prepared chromium-based catalyst to the reactor. For example, first, a nitrogen-containing compound (b) (particularly a pyrrole-containing compound), an alkylaluminum compound (c) and a halogen-containing compound (d) in a hydrocarbon and / or halogenated hydrocarbon solvent in the absence of α-olefin. ) And then reacting the obtained reaction solution for catalyst preparation with the chromium compound (a), whereby a chromium catalyst having excellent performance can be prepared.

In the present invention, the amount of the chromium compound used
Is usually 1.0 × 10^-7 ~ 0.
5 mol, preferably 1.0 × 10^-6~ 0.2 mol,
More preferably 1.0 × 10^-Five~ 0.05mol range
It is said. On the other hand, the amount of alkyl aluminum compound used
Is usually 0.05 mol per 1 mol of chromium compound
As mentioned above, in terms of catalytic activity and trimer selectivity,
Therefore, the content is preferably 0.1 mol or more. And the upper limit
Is usually 1.0 × 10^Four mol. Also contains nitrogen
The amount of the compound used is usually
0.001 mol or more, preferably 0.005 to
1000mol, more preferably 0.01-100mo
1 range. Also, the amount of halogen-containing compound used
Is in the same range as the amount of the nitrogen-containing compound used.

In the present invention, the chromium compound (a),
Molar ratio (a) of nitrogen-containing compound (b), alkylaluminum compound (c) and halogen-containing compound (d):
(B): (c): (d) is 1: 1 to 50: 1 to 200:
1 to 50 are preferred, and 1 to 1 to 30 to 10 to 150: 1.
To 30 are particularly preferred. By combining such specific conditions,
As an α-olefin low polymer, for example, hexene is 9
It can be produced in a yield of 0% or more (ratio to the total amount of production), and the purity of 1-hexene in hexene can be increased to 99% or more.

The most important feature of the present invention is that low polymerization of α-olefin is carried out under reaction conditions satisfying the following formulas (1) and (2). In the formula, T represents a reaction temperature (° C.), and P represents a reaction pressure (kg / cm ² G).

[0029]

T> 105 ° C. (1) P> 0.5T-15 (2)

Most of the above-mentioned publications state that the reaction temperature is preferably 70 ° C. or lower in order to make the shape of the by-product polymer in the reaction solution into a granular form which can be easily separated into solid and liquid. Japanese Patent Application Laid-Open No. H8-3216 discloses a general description of a reaction temperature of 0 to 250 ° C., a normal pressure to 25 ° C.
Although a reaction pressure of 0 kg / cm ² is described, in the examples, the reaction temperature is 80 ° C. and the reaction pressure is 35 kg / cm 2.
^Two conditions are adopted.

On the other hand, in the present invention, a reaction temperature of at least 105 ° C. is adopted, and the reaction temperature is 1
In the case of 10 ° C., it is necessary to employ a reaction pressure of at least 37.5 kg / cm ² G or more. According to the present invention, by using a reaction temperature of 105 ° C. or higher, preferably 120 to 150 ° C., the by-product polymer can exist in a dissolved state in the reaction solution. As a result, there is no problem such as that the by-product polymer adheres to the wall of the reactor.
It is possible to easily cope with a method of preventing the by-product polymer from being precipitated in the reactor and concentrating and separating the by-product polymer and the catalyst component together. Further, according to the present invention, since the reaction temperature is increased in a certain relation with the reaction pressure, the performance of the chromium catalyst does not decrease and high activity can be maintained. The residence time is generally in the range of 1 minute to 20 hours, preferably 0.5 to 6 hours.

In the present invention, the post-treatment such as the separation operation of each component after the completion of the reaction is not particularly limited. For example, it is not impossible to separate and remove the by-product polymer immediately after the reaction using a solid-liquid separation device.

In the above case, however, not only is a solid-liquid separator for the by-product polymer required separately from the separation of the metal component, but also the thermal history of each component in the reaction solution during the distillation separation. This makes it extremely difficult to separate the metalized metal component. That is, for example, when an attempt is made to separate a high boiling point component and a metal component by using a heating evaporator, the metal component adheres to the heat transfer surface of the heating evaporator and becomes substantially inseparable. And the metal component attached to the heat transfer surface
It interferes with the operation of the heating evaporator.

Therefore, in the present invention, it is preferable that the by-produced polymer is concentrated and separated together with the catalyst component as described later. According to such a separation mode, the catalyst component is very easily separated by the plasticity of the by-product polymer.
In addition, a solid-liquid separator for a by-product polymer can be omitted, and the process can be made compact.

In order to effectively carry out the above-mentioned simultaneous recovery process of the by-product polymer and the catalyst component utilizing the plasticity of the by-product polymer, a process line from the outlet of the reactor to the inlet of the product distillation column is required. Preferably, the temperature of the reaction solution is maintained at a temperature at which the by-product polymer can exist in a dissolved state in the reaction solution. As a result, it is also possible to avoid various troubles caused by adhesion and deposition of the by-product polymer in the process line (for example, incidental facilities such as pipes and product distillation columns). The temperature at which the by-product polymer can exist in a dissolved state in the reaction solution is the same as the above-mentioned reaction temperature, but the temperature may be raised if necessary.

In the present invention, in the process line from the outlet of the reactor to the inlet of the product distillation column,
Preferably, the catalyst components are maintained in a dispersed state in the reaction solution. Generally speaking, it is considered that the catalyst component is less likely to adhere and precipitate in the process line as much as the by-product polymer.

However, in the present invention, a compound which is soluble in a reaction solvent and has a ligand-forming ability for chromium is contained in a reaction solution in a process line from an outlet of a reactor to an inlet of a product distillation column. It is preferable to positively maintain the state of dispersion of the catalyst component in the reaction solution by adding.

Compound soluble in reaction solvent and capable of forming a ligand for chromium (hereinafter referred to as metal solubilizer)
In general, a low molecular compound having a -XH functional group (where X represents a hetero atom and H represents a hydrogen atom) or a low molecular compound having an active methylene group is used. Examples of the former include alcohols, phenols, carboxylic acids, primary or secondary amines, and ammonia, and examples of the latter include acetylacetone.

Specific examples of the above alcohols include methanol, ethanol, propanol, butanol, pentanol, hexanol, heptanol, octanol, nonanol, decanol, benzyl alcohol, ethylene glycol, trimethylene glycol, propanediol and the like. Examples of phenols include phenol, cresol, and hydroquinone. Specific examples of carboxylic acids include acetic acid, propionic acid, butyric acid, valeric acid, hexanoic acid, heptanoic acid, octanoic acid, nonanoic acid, and decane. Acid, benzoic acid, phenylacetic acid, phthalic acid, malonic acid, succinic acid, glutaric acid, adipic acid, acrylic acid, maleic acid, fumaric acid, salicylic acid, etc. Specific examples of primary or secondary amines include , As a component of the catalyst Each amines described above can be mentioned.

The use ratio of the metal solubilizer can be selected from a wide range ranging from a trace amount to the amount of the solvent, and is usually 0.001 to 50% by weight, preferably 0.1 to 50% by weight, as the concentration in the solvent. It is in the range of 01 to 10% by weight. The timing of adding the metal solubilizing agent may be selected at any stage before the components are separated by distillation in the reaction solution. When there are a plurality of distillation separation steps, they may be added immediately before the final distillation step in which metallization of the metal component is most likely to occur, but it is preferable to add them immediately after the reaction step. In addition, a method in which an antistatic agent already proposed in the field of polymerization of α-olefin is added to the reaction solution instead of the metal solubilizing agent can also be suitably used.

According to the preferred embodiment of the present invention,
The loss of both the by-product polymer and the catalyst component up to the simultaneous recovery process can be minimized.

In the present invention, the reaction solution from the low polymerization reactor is supplied to a degassing column to recover unreacted α-olefin,
The reaction solution from the degassing column is supplied to the product distillation column, and the generated α-olefin low polymer is recovered as a distillate, and the by-product polymer and the catalyst component are both concentrated and recovered as a bottoms. Is preferred.

In the conventional α-olefin low polymerization process which has been industrialized, the separation of the by-product polymer differs from the above-mentioned preferred embodiment of the present invention by using a solid-liquid separation device separately from the catalyst component. Had been In that case, the by-product polymer is separated without lowering the pressure and almost maintaining the pressure in the reaction. The reason is particularly in the production of 1-hexene according to the above-mentioned conventional method,
The yield of 1-hexene is not sufficient, and a large amount of low-boiling components (1-butene) of about 15% by weight or more is produced as by-products. This is because the cooling load required for the distillation separation of 1-butene (boiling point: −6.47 ° C.) becomes large.

Therefore, in the case of the above-mentioned conventional method, after the reaction, the by-product polymer is separated without lowering the pressure, then the 1-butene is separated by distillation, and the pressure must be gradually reduced in the subsequent unit operation. Absent. However, the method of separating the by-product polymer in a pressurized state not only requires a special solid-liquid separation device, but also has poor operability, and sometimes the solid-liquid separation device is blocked by the by-product polymer. There are significant disadvantages.

On the other hand, in the low-polymerization of α-olefins by the catalyst system used in the method of the present invention, low-polymers of α-olefin other than 1-hexene, particularly 1-butene are less produced, Since hexene is obtained in a high yield, it is not only necessary to recover 1-butene, but also in the case of recovering by atmospheric distillation, the cooling load required for distillation separation can be remarkably reduced.

As a result, in the present invention, the degassing operation can be performed prior to the other unit operations in accordance with the above-mentioned preferred embodiment, thereby eliminating the complicated steps of the conventional method and the disadvantages thereof. In addition to being avoidable, there is an advantage that the subsequent unit operation can be operated at a temperature near normal pressure, which is excellent in operability.

In the present invention, the degassing treatment is usually carried out by
The pressure is reduced to 15 kg / cm ² G or less, but it is preferable to reduce the pressure to 1.9 kg / cm ² G or less, which is regarded as a second-class high-pressure container, from the viewpoint of the rules for handling the high-pressure vessel. If the pressure is reduced to 0.2 kg / cm ² G or less, almost the same operation as normal pressure can be performed, so that it is more preferable.

In the present invention, the concentration and separation of the by-product polymer and the catalyst component from the reaction solution can be carried out simultaneously with the simple removal of all components having a low boiling point from the degassed reaction solution. It can be carried out simultaneously with the last distillation separation when each component is successively separated from the reaction solution by distillation.

For example, when α-olefin is ethylene, 1-hexene is obtained as an α-olefin low polymer. In this case, after the reaction, ethylene is removed, and then 1-hexene and a solvent are removed from the reaction mixture. And the catalyst component is concentrated and separated together with the by-product polyethylene. Then, the obtained concentrated liquid containing the by-product polymer and the catalyst component can be directly discarded.

As described above, in the catalyst system used in the method of the present invention, 1-butene is less produced as a by-product and 1-hexene can be obtained in high yield. By treating in a product distillation column, 1-hexene and the reaction solvent can be separated into a high boiling component including a by-product polymer and a catalyst component. As a result, the most compact and economical process can be realized. Can be realized.

In the preferred embodiment of the present invention, at least a part of each of the by-produced polymer and the catalyst component is simultaneously separated. Simultaneous separation is performed for all components. And in any case,
The bottoms containing the by-product polymer and the catalyst component recovered from the product distillation column are supplied to a heating evaporator to recover the high boiling components and to further concentrate and recover the by-product polymer and the catalyst component. preferable.

As the above-mentioned heating evaporator, conventionally known various types can be used. For example, a thin film evaporator equipped with a scraping blade that rotates with respect to a heat transfer surface of a cylindrical type,
An evaporator having a built-in plate fin heater can be used. An evaporator with a built-in plate-fin heater
The high-viscosity fluid can be heated instantaneously by the fins arranged at high density, and the volatile substances contained therein can be efficiently removed.

As the heating evaporator having the above structure, for example, "Hibiscus Evaporator" (trade name) manufactured by Mitsui Engineering & Shipbuilding Co., Ltd. and the like can be mentioned. When such a heating evaporator is used, the by-product polymer and the catalyst component concentrated by the built-in plate-fin type heater flow down from the lower portion of the heating evaporator due to the plasticity of the by-product polymer. Therefore, it can be cut and recovered easily after being cooled appropriately.

In the present invention, a particularly recommended heating evaporator is a monotube evaporator provided with a heating tube having a sufficient length and a collecting can capable of holding under reduced pressure. As the heating evaporator having such a structure, for example, "CRUX SYSTEM" (trade name) manufactured by Hosokawa Mikaron Co., Ltd. and the like can be mentioned. In such a monotube evaporator, the concentrated solution heated and evaporated by the heating tube is spouted at a high speed of about the speed of sound to a collecting can to efficiently remove volatile substances contained therein. The by-product polymer and the catalyst component concentrated in the collection can flow down from the lower part of the collection chamber due to the plasticity of the by-product polymer. Therefore, it can be cut and recovered easily after being cooled appropriately.

On the other hand, the recovered α-olefin low polymer is purified if necessary. For purification, distillation purification is usually employed, and a target component can be recovered with high purity. In the present invention, in particular, 1-hexene of high purity can be industrially advantageously produced from ethylene. Further, L-LDPE, which is a useful resin, can be produced from 1-hexene obtained by the production method of the present invention by a polymerization reaction using a known polymerization catalyst.

[0056]

EXAMPLES Hereinafter, 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 unless it exceeds the gist of the invention.

Example 1 A complete mixing tank type reactor, a degassing tank, a product distillation column equipped with a 30-stage product distillation column and an evaporator equipped with two side stream withdrawing sections, and a reactor and a degasser Between the gas tank and the gas tank, a continuous low-polymerization reaction of ethylene was performed according to a process provided with a compressor for circulating degassed ethylene into the reactor. In addition, a 20-liter autoclave provided with two supply pipes was used as a complete mixing tank type reactor, and a heating tube having a length of 8 m and a collecting can capable of holding under reduced pressure were used as an evaporator. Mono tube type evaporator “CRUX SYST”
EM "(trade name, manufactured by Hosokawa Mikaron Co., Ltd.).

A solution of chromium (III) -2-ethylhexanoate (a) in n-heptane and hexachloroethane (d) together with ethylene from one supply pipe of the complete mixing tank reactor.
N-heptane solution was continuously supplied, and the n-heptane solution of 2,5-dimethylpyrrole (b) and the n-heptane solution of triethylaluminum (c) were continuously supplied from the other supply pipe. . (A): (b): (c):
The molar ratio of (d) is 1: 6: 40: 4. The reaction conditions were 120 ° C. × 50 kg / cm ² G.

The reaction liquid continuously withdrawn from the reactor was supplied to the degassing tank while maintaining the temperature at 120 ° C. The degassed reaction liquid was supplied to the product distillation column while substantially maintaining the above temperature, and the bottom liquid was supplied to the evaporator and concentrated. Eighth from the bottom of the product distillation column
The solvent n-heptane was discharged from the side draining part at the 26th stage.
The product hexene was extracted and collected as side cuts from the side draining part of the stage, and components having a boiling point lower than that of hexene were distilled off from the top of the column and collected.

In the evaporator, the evaporated high-boiling components were condensed and recovered, and the catalyst component concentrated together with the by-product polyethylene was recovered from the lower part of the collection chamber. On the other hand, ethylene degassed in the degassing tank is pressurized by the compressor and circulated to the reactor, and n-heptane recovered from the product distillation column is circulated to the reactor via a circulation pipe. Was done. Table 1 shows the operating conditions of each unit after the product distillation column. Table 2 shows the mass balance in the above process. In Table 2, Cr (2EHA) 3 is chromium (III) −
Represents 2-ethylhexanoate.

[0061]

[Table 1]

[0062]

[Table 2] ──────────────────────────────────── Reaction liquid Degassing liquid Distillation column Evaporator Evaporation vesselBottom liquid Evaporation component Concentration component Unit: / hr 42.0kg 35.9kg 0.28kg 0.25kg 29.8g Cr (2EHA) 3 (ppm) 3.0 3.5 134 0.0 0.127wt% 2,5-dimethylmethyl (ppm) 3.6 4.2 159 177.7 0.0 Triethylaluminum (ppm) 28.4 33.0 1271 0.0 1.20wt% Hexachloroethane (ppm) 7.4 8.6 329 368.4 0.0 Heptane (wt%) 64.7 75.8 0.0 0.0 0.0 Ethylene (wt%) 14.6 0.0 0.0 0.0 0.0 C6 component (wt%) 20.0 23.4 0.0 0.0 0.0 High boiling component (wt%) 0.60 0.70 89.4 99.9 0.0 Polyethylene (ppm) 700 820 10.43wt% 0.0 98.7wt% Total (wt%) 100.0 100.0 100.0 100.0 100.0 1-hexene content in the C6 component: 99.5% by weight 1-hexene / ethylene (molar ratio) = 0.45 Catalyst efficiency: 614,198 g-1-hexene / g-chromium ─────────────────────────

The operation of the evaporator in the above process is as follows:
Since the catalyst component containing the metal was recovered as a concentrated mixture together with the by-produced polyethylene, it dropped and separated from the lower part of the collection chamber by its own weight due to the plasticity of the polyethylene, and was performed well.

Example 2 A continuous low-polymerization reaction of ethylene was carried out in the same manner as in Example 1 except that tetrachloroethane was used as the halogen-containing compound. Table 3 shows the mass balance of this example. The operation of the evaporator was as good as in Example 1.

[0065]

[Table 3] ──────────────────────────────────── Reaction liquid Degassing liquid Distillation tower Evaporator Evaporation vesselBottom liquid Evaporation component Concentration component Unit: / hr 38.5kg 32.9kg 0.26kg 0.23kg 27.3g Cr (2EHA) 3 (ppm) 3.0 3.5 134 0.0 0.127wt% 2,5-dimethylmethyl (ppm) 3.6 4.2 159 177.7 0.0 Triethylaluminum (ppm) 28.4 33.0 1272 0.0 1.20wt% Tetrachloroethane (ppm) 5.2 6.1 234 261.2 0.0 Heptane (wt%) 66.9 78.4 0.0 0.0 0.0 Ethylene (wt%) 14.6 0.0 0.0 0.0 0.0 C6 component (wt%) 17.8 20.8 0.0 0.0 0.0 High boiling component (wt%) 0.60 0.70 89.4 100.0 0.0 Polyethylene (ppm) 700 820 10.43wt% 0.0 98.7wt% Total (wt%) 100.0 100.0 100.0 100.0 100.0 1-hexene content in the C6 component: 99.5% by weight 1-hexene / ethylene (molar ratio) = 0.41 Catalyst efficiency: 546,636 g-1-hexene / g-chromium ─────────────────────────

Example 3 Continuous low-polymerization of ethylene was carried out in the same manner as in Example 1 except that octanoic acid (2-ethylhexanoic acid) was continuously added as a metal solubilizer to the degassing tank. The reaction was performed. The amount of the metal solubilizing agent added was such that the concentration in the reaction solvent in the degassing tank was 0.022% by weight.

The bottom liquid of the product distillation column is sampled,
Analysis of the deposited metal component was carried out, but the deposited metal component was not substantially present. In addition, the analysis of the deposited metal component
A method of filtering a sample with a filter paper (5A), washing the filter paper surface with an n-heptane solution, washing with a 10% by weight aqueous nitric acid solution, and measuring the concentration of a metal component in the aqueous nitric acid solution by high-frequency plasma emission spectroscopy Made by. Table 4 shows the mass balance of this example. The operation of the evaporator was as good as in Example 1.

[0068]

[Table 4] Reaction liquid Degassing liquid Distillation column Evaporator Evaporation vesselBottom liquid Evaporation component Concentration component Unit: / hr 42.5kg 36.3kg 0.35kg 0.32kg 31.9g Cr (2EHA) 3 (ppm) 3.0 3.5 363 0.0 0.399wt% 2,5-dimethylmethyl (ppm) 3.6 4.2 430 473.4 0.0 Triethylaluminum (ppm) 28.4 33.0 3443 0.0 3.79wt% Hexachloroethane (ppm) 7.4 8.6 892 981.4 0.0 Heptane (wt%) 62.1 72.7 0.0 0.0 0.0 Ethylene (wt%) 14.6 0.0 0.0 0.0 0.0 C6 component (wt%) 22.5 26.3 0.0 0.0 0.0 High boiling component (wt%) 0.75 0.88 90.8 99.9 0.0 Polyethylene (ppm) 800 936 8.71wt%-95.8wt% Total (wt%) 100.0 100.0 100.0 100.0 100.0 1-hexene content in C6 component: 99.5% by weight 1-hexene / ethylene (molar ratio) = 0.51 Catalyst efficiency: 690,972 g-1-hexene / g-chromium ─────────────────────────

Example 4 A continuous low-polymerization reaction of ethylene was carried out in the same manner as in Example 1, except that the reaction temperature and pressure were changed to 120 ° C. and 70 kg / cm ² G. Table 5 shows the mass balance of this example. The operation of the evaporator is described in Example 1.
As good as.

[0070]

[Table 5] ──────────────────────────────────── Reaction liquid Degassing liquid Distillation tower Evaporator Evaporation vesselBottom liquid Evaporation component Concentration component Unit: / hr 52.3kg 40.4kg 1.06kg 0.99kg 71.1g Cr (2EHA) 3 (ppm) 3.0 3.9 44 0.0 0.066wt% 2,5-dimethylmethyl (ppm) 3.6 4.6 52 56.1 0.0 Triethylaluminum (ppm) 28.4 37.0 419 0.0 0.63wt% Hexachloroethane (ppm) 5.2 6.8 77 82.5 0.0 Heptane (wt%) 40.3 52.1 0.0 0.0 0.0 Ethylene (wt%) 22.7 0.0 0.0 0.0 0.0 1-Hexene (wt%) 35.0 45.3 0.0 0.0 0.0 High boiling component (wt%) 1.90 2.46 93.3 100.0 0.0 Polyethylene (ppm) 1350 1746 6.63wt% 0.0 99.3wt% Total (wt%) 100.0 100.0 100.0 100.0 100.0 1-hexene content in C6 component: 99.5% by weight 1-hexene / ethylene (molar ratio) = 0.51 Catalyst efficiency: 1,074,846 g-1-hexene / g-chromium ─────────────────────────

Examples 5 to 8 In Example 3, 1-hexanol (Example 5), hexylamine (Example 6), ammonia (Example 7), acetylacetone were used as metal solubilizers to be added to the degassing tank. A continuous low-polymerization reaction of ethylene was carried out in the same manner as in Example 3 except that (Example 8) was used. As a result, the operation of the evaporator was as good as in Example 3. Example 3
Sample the bottom liquid of the product distillation column in the same manner as
Analysis of the deposited metal component was carried out, but in any of the examples, substantially no deposited metal component was present.

Example 9 At room temperature under a nitrogen atmosphere, 2,5-dimethylpyrrole (2
9.59 mg, 0.311 mmol) in toluene solution 5
Hexachloroethane (49.23 mg, 0.20
8 mmol) was added. To the resulting solution was added a toluene solution (1.55 ml) of triethylaluminum (177.8 mg, 1.55 mmol) and reacted for 30 minutes. To the resulting solution was added a toluene solution (1 ml) of chromium (III) 2-ethylhexanoate (50 mg, 0.102 mmol), and the mixture was reacted for 15 minutes. Thereafter, toluene was distilled off under reduced pressure at room temperature. The obtained brown oil was diluted with cyclohexane (5 ml), and the resulting mixture was diluted with a catalyst solution (5.2 ml).
And

300 ml dried in a dryer at 150 ° C.
After assembling the autoclave in hot, the atmosphere was replaced with vacuum nitrogen. At room temperature under a nitrogen atmosphere, cyclohexane (125 m
l) and the above catalyst solution (0.68 ml) were charged into an autoclave. The autoclave was heated to 120 ° C. and ethylene was introduced into the autoclave until the total pressure reached 50 kg / cm ² G. Then, the total pressure was 50 kg / cm ² G,
The reaction temperature was maintained at 120C. After 30 minutes, ethanol was injected into the autoclave to stop the reaction. Table 6 shows the results of the composition analysis of the products by gas chromatography.

[0074]

[Table 6] <Amount of total product (g)> 43.0 g <Composition distribution (wt%)> C4 0.05 C6 Total 96.8 1-hexene content in C6 99.6 C8 0.5 C10-20 2.6 By-product polyethylene 0.02 <Catalytic efficiency> 62,300 g-1 -Hexene / g-Chromium ────────────────────────────────────

Comparative Example 1 In Example 1, only the reaction pressure was 35 kg / cm ² G
A continuous low-polymerization reaction of ethylene was performed in the same manner as in Example 1 except that the reaction was changed to Example 1. As a result, the catalyst efficiency was 327,96
2 g-1-hexene / g-chromium, which was about 47% lower than in Example 1.

Comparative Example 2 In Example 9, only the reaction pressure was changed to 35 kg / cm ² G
A continuous low-polymerization reaction of ethylene was carried out in the same manner as in Example 9 except that the reaction was changed to. As a result, the catalyst efficiency is 34,265
g-1-hexene / g-chromium, which was about 45% lower than in Example 9.

Example 10 A 2-liter autoclave having two catalyst supply tubes and one reaction solution withdrawing tube was assembled after being dried in a dryer at 150 ° C., and was replaced with vacuum nitrogen. The autoclave was supplied with n-heptane at a rate of 0.067 mmol / hr for 2,5-dimethylpyrrole, 0.45 mmol / hr for trityl aluminum and 0.045 mmol / hr for hexachloroethane from one of the catalyst supply tubes. The solution was continuously supplied as a solution, and chromium (III) 2-ethylhexanoate was added together with ethylene to 0.011 mmol / hr (5.4 mg) from the other catalyst supply tube.
/ Hr) as a continuous n-heptane solution. The total supply of n-heptane to the autoclave is 1.8 l / hr.

Then, the temperature of the autoclave is set to 105 ° C.
, Ethylene was continuously supplied into the autoclave so that the total pressure became 50 kg / cm ² G, and a low polymerization reaction of ethylene was carried out. On the other hand, the reaction solution was continuously extracted from the autoclave via a reaction solution extraction tube so that the internal volume became 1 liter. Then, the extracted reaction liquid was introduced into a degassing tank, degassed to normal pressure, and the liquid component and the gas component were analyzed by gas chromatography. Table 7 shows the results.

Examples 11 to 16 and Comparative Examples 3 to 5 The same procedures as in Example 10 were carried out except that the supply rate of the catalyst-forming component to the autoclave or the reaction conditions were changed as shown in Tables 7 and 8. The reaction was performed similarly. The results are shown in Table 7 or Table 8. In these tables, the halogen compound type A represents hexachloroethane, and the unit of the catalytic efficiency is g-1-hexene / g-chromium.

[0080]

[Table 7] Example 10 11 12 13 14 Solvent flow rate (L / hr) 1.8 4 1.8 4 1.8 Cr compound amount (mg / hr) 5.4 12 5.4 12 5.4 Cr compound amount (mmol / hr) 0.011 0.025 0.011 0.025 0.011 2,5-DMP amount (mmol / hr) 0.067 0.149 0.067 0.149 0.067 Et ₃ Al amount (mmol / hr) 0.45 1.00 0.45 1.00 0.45 Halocene Compound type A A A A A A Halocene Compound amount (mmol / hr) 0.045 0.100 0.045 0.100 0.045 Catalyst component molar ratio (a: b: c: d) 1: 6: 40: 4 1: 6: 40: 4 1: 6: 40: 4 1: 6: 40: 4 1: 6: 40: 4 Reaction pressure (Kg / cm ² G) 50 50 70 70 50 Reaction Temperature (℃) 105 105 105 105 120 Residence time (hr) 0.25 0.12 0.17 0.1 0.28 Product amount (g / hr) 551 838 907 1129 385 Cr concentration in reaction zone (ppm) 0.26 0.29 0.19 0.24 0.3 Ethylene concentration in reaction zone ( ppm) 3.23 3.23 4.62 4.21 2.7 1-hexene / ethylene (molar ratio) 0.48 0.37 0.38 0.29 0.45 Composition distribution (wt%) C ₆ whole 95.9 96.8 95.8 96.5 95.5 1-hexen content in C ₆ 99.5 99.5 99.6 99.6 99.5 By-product PE (wt%) 0.035 0.023 0.064 0.051 0.045 Catalyst efficiency (× 10 ⁵ ) 9.45 6.47 15.5 8.71 6.60 ───────────────────── ───────────────

[0081]

Table 8 Example Comparative Example 15 16 3 4 5 Solvent Flow rate (L / hr) 1.8 4 1.8 4 4 Cr compound amount (mg / hr) 5.4 12 5.4 12 12 Cr compound amount (mmol / hr) 0.011 0.025 0.011 0.025 0.025 2,5-DMP amount (mmol / hr) 0.067 0.149 0.067 0.149 0.149 Et ₃ Al Amount (mmol / hr) 0.45 1.00 0.45 1.00 1.00 Halocan Compound Type A A A A A A Halocan Compound Amount (mmol / hr) 0.045 0.100 0.045 0.100 0.100 Catalyst Component Molar Ratio (a: b: c: d ) 1: 6: 40: 4 1: 6: 40: 4 1: 6: 40: 4 1: 6: 40: 4 1: 6: 40: 4 Reaction pressure (Kg / cm ² G) 70 70 50 50 35 Reaction temperature (° C) 120 120 140 140 140 Residence time (hr) 0.2 0.1 0.3 0.14 0.17 Product amount (g / hr) 653 986 209 387 33 Cr concentration in reaction zone (ppm) 0.23 0.26 0.34 0.35 0.42 Ethylene concentration in reaction zone (ppm) 3.88 3.88 2.29 2.29 1.55 1- hexene / ethylene (molar ratio) 0.38 0.29 0.32 0.28 0.04 composition distribution (wt%) C ₆ total 95.4 96.6 95.1 96.7 94.3 1-hexen in C ₆ The amount 99.5 99.5 98.9 99.1 95.1 byproduct PE (wt%) 0.134 0.03 0.305 0.059 1.03 catalytic efficiency ^{(× 10 5) 11.2 7.61 3.59} 3.06 0.253 ──────────────────── ────────────────

[0082]

According to the present invention described above, it is possible to employ a higher reaction temperature without deteriorating the performance of the chromium catalyst, and therefore, it is possible to prevent the by-product polymer from being precipitated in the reactor. There is provided an industrially advantageous method for producing an α-olefin low polymer which can easily cope with a method of concentrating and separating both a by-product polymer and a catalyst component.

Claims (12)

[Claims] 1. Low polymerization of α-olefin is carried out in a low polymerization reactor in the presence of a chromium catalyst and a reaction solvent under reaction conditions satisfying the following formulas (1) and (2). A method for producing an α-olefin low polymer. T ≧ 105 ° C. (1) P> 0.5T−15 (2) (T is reaction temperature (° C.), P is reaction pressure (kg / cm)
Representing a ² G). ) 2. At least a chromium compound (a), a nitrogen-containing compound (b), an alkylaluminum compound (c)
2. A chromium-based catalyst comprising a combination of
The production method described in 1. 3. The process according to claim 1, wherein a chromium-based catalyst comprising at least a combination of a chromium compound (a), a nitrogen-containing compound (b), an alkylaluminum compound (c), and a halogen-containing compound (d) is used. Method. 4. The molar ratio of the chromium compound (a), nitrogen-containing compound (b), alkylaluminum compound (c) and halogen-containing compound (d) (a) :( b) :( c):
4. The method according to claim 2, wherein (d) is 1: 1 to 50: 1 to 200: 1 to 50. 5. The low polymerization of α-olefin by contacting α-olefin with a chromium-based catalyst in such a manner that the chromium compound (a) and the alkylaluminum compound (c) do not come into contact in advance. The production method according to any one of the above. 6. Contacting a nitrogen-containing compound (b), an alkylaluminum compound (c) and a halogen-containing compound (d) in a hydrocarbon and / or halogenated hydrocarbon solvent in the absence of α-olefin, And a chromium-based catalyst prepared by reacting the obtained reaction solution for catalyst preparation with a chromium compound (a).
Or the production method according to 4. 7. The reaction solution from the low polymerization reactor is supplied to a degassing column to recover unreacted α-olefin, and the reaction solution from the degassing column is supplied to a product distillation column to produce α-olefin. While recovering the olefin low polymer as a distillate, the by-product polymer and the catalyst component are both concentrated and recovered as a bottoms,
At this time, in the process line from the outlet of the low polymerization reactor to the inlet of the product distillation column, the temperature of the reaction solution is maintained at a temperature at which the by-product polymer can exist in a dissolved state in the reaction solution. The production method according to any one of the above. 8. The production method according to claim 7, wherein the α-olefin low polymer, the reaction solvent, the by-product polymer and the high boiling point component containing the catalyst component are separated by a single product distillation column. 9. A bottom product containing a by-product polymer and a catalyst component recovered from the product distillation column is supplied to a heating evaporator to recover a high-boiling component and further concentrate the by-product polymer and the catalyst component. The production method according to claim 7, wherein the product is collected by recovery. 10. The α-olefin low polymer according to claim 9, wherein the heating evaporator is a monotube evaporator provided with a heating tube having a sufficient length and a collecting can capable of holding under reduced pressure. Production method. (11) the α-olefin is ethylene;
The method according to any one of claims 1 to 10, wherein the olefin low polymer is mainly 1-hexene. 12. The production method according to claim 11, wherein 1-hexene, a reaction solvent, and a high-boiling component containing a by-product polymer and a catalyst component are separated by a single product distillation column.