JPH1087518A - Production of 1-hexene - Google Patents

Abstract

PROBLEM TO BE SOLVED: To produce 1-hexene in preventing attaching of a by-produced polymer to a reactor to maintain a heat-removing efficiency at a high level, by performing a trimerization reaction of ethylene while circulating a reaction solution in an annular flowing path of a loop-type reactor. SOLUTION: The trimerization reaction of ethylene using a chromium-based catalyst by using a loop-type reactor having an annular flowing path while circulating a reaction solution containing ethylene and a chromium-based catalyst in the flowing path. Concretely, e.g. in a case of performing a continuous reaction, a solvent, ethylene, a catalyst, etc., are continuously supplied from introducing pipes 6 and 7 and a reaction solution is continuously extracted from a downward extracting pipe 10, and an annular flowing path comprising a rising pipe 2, a lowering pipe 3, a downward transferring pipe 4 and an upward transferring pipe 5 is circulated by a circulating means 8 such as a turbo- type pump to make a by-produced polymer not deposit on a pipe wall but suspend in the reaction solution. As the catalyst, one comprising a chromium compound, a nitrogencontaining compound, an alkylaluminum compound or a halogencontaining compound is preferable.

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 1-hexene, and more particularly to an industrially advantageous method for producing 1-hexene by a trimerization reaction of ethylene.

[0002]

2. Description of the Related Art In recent years, many proposals have been made as industrially advantageous methods for producing 1-hexene by trimerizing ethylene. For example, JP-A-7-118174,
-118175, 7-118326, 7-11
Nos. 8327, 7-149671, 7-14967
No. 2, No. 7-149673, No. 7-149674,
7-149675, 7-149676, 7-
149677 and 7-165815,
At least a method for producing 1-hexene from ethylene using a chromium-based catalyst comprising a combination of a chromium compound (a), an amine or a metal amide (nitrogen-containing compound) (b), and an alkylaluminum compound (c). Improvements have been proposed.

[0003] Japanese Patent Application Laid-Open Nos. 8-3216 and 8-13
No. 4131 discloses at least a chromium compound (a), an amine or a metal amide (nitrogen-containing compound).
A method for producing 1-hexene from ethylene using a chromium-based catalyst comprising a combination of (b), an alkylaluminum compound (c), and a halogen-containing compound (d) has been proposed. In particular, JP-A-7-149672 and JP-A-7-149677 relate to a production method directed to 1-hexene. Among these proposals, a higher chromium compound (a) and an alkylaluminum compound (c) are obtained by conducting a trimerization reaction of ethylene by using a catalyst prepared in such a manner that the chromium compound (a) is brought into contact with the alkylaluminum compound (c) for the first time. It is also disclosed that the desired 1-hexene can be obtained with a selectivity.

[0004]

However, none of the methods proposed so far can completely suppress the by-product of the polymer. The by-produced polymer adheres to the reactor, causing various problems in the reaction operation.
For example, when a trimerization reaction of ethylene is carried out using a general-purpose stirred tank reactor having a cooling jacket or a cooling coil inside, a by-product polymer adheres to a cooling wall surface, thereby lowering heat removal efficiency. Since the ethylene trimerization reaction is a large exothermic reaction, a decrease in the heat removal efficiency makes it difficult to control the reaction temperature and reduces the productivity. Accordingly, an object of the present invention is to provide a method for producing 1-hexene by trimerizing ethylene while suppressing adhesion of a by-product polymer to a cooling wall surface of a reactor. Another object of the present invention is to provide a method for producing 1-hexene by trimerizing ethylene while maintaining a high heat removal efficiency of the reactor.

[0005]

According to the present invention, when trimerizing ethylene using a chromium-based catalyst to produce 1-hexene, a loop reactor having an annular flow path is used. By performing a trimerization reaction of ethylene while circulating a reaction solution containing ethylene and a catalyst in the passage, it is possible to avoid various obstacles due to adhesion of a by-product polymer to the reactor.

[0006]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described in more detail. FIG. 1 is a conceptual diagram of an example of a loop reactor having an annular flow path used in the present invention. The reactor 1 has an ascending pipe 2, a descending pipe 3, a lower transition pipe 4, and an upper transition pipe 5 that form an annular flow path. The lower transition pipe 4 is provided with introduction pipes 6 and 7 for supplying a solvent, a catalyst, ethylene and the like to the reactor. The upper transition pipe 5 is provided with a downward extraction pipe 10 for extracting the reaction solution in the reactor, and an upward extraction pipe 11 for extracting gas similarly. A circulating means 8 for circulating the reaction solution inside the annular flow path is provided. As the circulating means 8, a turbo pump is usually used. A jacket 9 for circulating a cooling medium for controlling the reaction temperature is provided outside each of the tubes constituting the annular flow path.

The loop reactor shown in FIG. 1 can be applied to a batch reaction and a continuous reaction. In the case of a batch reaction, first, a solvent, ethylene, a catalyst, and the like are supplied from the introduction pipes 6 and 7 until a predetermined pressure is reached, and then a heating medium is supplied to the jacket while circulating the reaction solution to thereby obtain a predetermined reaction temperature. To cause a trimerization reaction. Once the reaction has started, a cooling medium is supplied to the jacket to remove the heat of reaction so as to maintain a predetermined reaction temperature. Since ethylene is consumed and the pressure decreases as the reaction proceeds, it is preferable to maintain ethylene at a predetermined pressure by replenishing ethylene from the inlet tube. In addition, since the activity of the catalyst decreases with time, the catalyst may be additionally supplied during the reaction, or a halogen-containing compound or an alkylaluminum compound may be supplied to activate the catalyst to recover the activity. it can. In addition,
During the reaction operation, the reaction solution is circulated by the circulation means 8 at a flow rate of 3 to 15 m / sec. As a result, the reaction solution becomes turbulent, and the by-product polymer is prevented from adhering to the tube wall.

When the reaction is completed, the upward extraction pipe 11 is opened to discharge the gas in the system, and then the downward extraction pipe 10 is opened.
And release the reaction solution. During the operation of extracting the reaction solution, the circulating means 8 keeps the system in a turbulent state so that the by-product polymer is extracted together with the reaction solution without depositing on the tube wall. When performing a continuous reaction using the loop reactor shown in FIG. 1, a solvent, ethylene, a catalyst, and the like are continuously supplied from the introduction pipes 6 and 7, and the reaction solution is continuously supplied from the downward extraction pipe 10. You only have to pull it out. Also in this case, the system is maintained in a turbulent state by the circulating means 8 so that the by-product polymer is suspended in the reaction solution without depositing on the tube wall.

[0009] The reaction liquid discharged from the reactor is first removed of floating by-product polymer using a suitable solid-liquid separator, and then distilled to recover 1-hexene. In the present invention, the chromium-based catalyst used for the ethylene trimerization reaction comprises at least a combination of a chromium compound (a), a nitrogen-containing compound (b) and an alkylaluminum compound (c). Preferably, 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 further used in combination with the halogen-containing compound (d). Can be

As described above, these three-component or four-component chromium-based catalysts are all known, and in the present invention, they can be appropriately selected from known chromium-based catalysts. For example, as a three-component chromium-based catalyst, JP-A-7-118174 discloses [0008] to [002].
Those comprising the components described in [5] can be used. Further, as the four-component chromium-based catalyst, JP-A-8-3216 discloses [0011] to [002].
8], and [00] of JP-A-8-134131.
[09] to [0041].

Preferably, the chromium-based catalyst used in the present invention is prepared from the following components. That is, as the chromium compound (a), chromium (II) acetate, chromium (II)
I) A chromium carboxylate such as acetate, chromium (III) -2-ethylhexanoate, chromium (III) benzoate, and chromium (III) naphthenate is used. Particularly, it is preferable to use chromium (III) -2-ethylhexanoate.

As the nitrogen-containing compound (b), a secondary amine is used, among which pyrrole, 2,5-dimethylpyrrole, 3,4-dimethylpyrrole, 3,4-dichloropyrrole, 2,3,4,4 5-tetrachloropyrrole, 2
-It is preferable to use pyrrole such as acetylpyrrole or a derivative thereof. Particularly preferred is 2,5-dimethylpyrrole.

As the alkylaluminum compound (c), trialkylaluminums such as trimethylaluminum, triethylaluminum and triisobutylaluminum are used. Particularly preferred is triethylaluminum. When the halogen-containing compound (d) is used, the compound described in JP-A-8-134131 may be used.
A linear halohydrocarbon having 2 or more carbon atoms and having at least two halogen atoms is used. For example, it is preferable to use 1,1,1-trichloroethane, 1,1,2,2-tetrachloroethane, pentachloroethane, hexachloroethane, or the like.

The chromium-based catalyst may be prepared in advance and supplied to the reactor, or the components constituting the catalyst may be supplied to the reactor to form the catalyst in the reactor. When a catalyst prepared in advance is used, first, a nitrogen-containing compound (b), an alkylaluminum compound (c) and a halogen-containing compound (d) are brought into contact in a solvent in the absence of an α-olefin to cause a reaction. . As the solvent, a hydrocarbon and / or a halogenated hydrocarbon is used. When a halogenated hydrocarbon is used as the solvent, this can also serve as the halogen-containing compound (d). Next, when the reaction solution obtained above and the chromium compound (a) are mixed, a chromium-based catalyst having excellent performance is obtained.

When the components constituting the catalyst are supplied to the reactor to form the catalyst in the reactor, the chromium compound (a) and the alkylaluminum compound (c) are first reacted in the presence of ethylene. It is preferred to supply each component in a contacting manner. In this way, the ethylene trimerization reaction proceeds particularly selectively, and 1-hexene can be obtained from ethylene in high yield. Examples of the supply form of such a catalyst component include, for example, [0029] to [0031] of JP-A-7-118174, [0029] to [0032] of JP-A-8-3216, and JP-A-8-1341.
The details are described in [0045] to [0050] of Japanese Patent Publication No. 31 and some examples are as follows.

(1) A solution containing a chromium compound (a), a solution containing a nitrogen-containing compound (b), an alkylaluminum compound (c) and a halogen-containing compound (d), and a method of feeding ethylene to a reaction zone, respectively. . (2) A method comprising supplying a solution containing a chromium compound (a), a nitrogen-containing compound (b) and a halogen-containing compound (d), a solution containing an alkylaluminum compound (c), and ethylene to a reaction zone.

(3) A solution containing a chromium compound (a) and a halogen-containing compound (d), a solution containing a nitrogen-containing compound (b) and an alkylaluminum compound (c), and a method of supplying ethylene to the reaction zone. (4) A method including supplying a solution containing a chromium compound (a) and a nitrogen-containing compound (b), a solution containing an alkylaluminum compound (c) and a halogen-containing compound (d), and ethylene to a reaction zone. (5) A method in which a chromium compound (a), a nitrogen-containing compound (b), an alkylaluminum compound (c), a halogen-containing compound (d) and ethylene are separately supplied to a reaction zone.

The amount of the catalyst supplied to the reactor is such that the chromium compound (a) is usually 1.0 × 10
^{-7 to} 0.5 mol, preferably 1.0 × 10 ^{-6 to} 0.2
mol, more preferably 1.0 × 10 ^{−5 to} 0.05 mo
It is an amount that becomes 1. The ratio of the other components to the chromium compound (a) is 1 to 50 mol, particularly 1 to 3 mol, per mol of the chromium compound (a).
0 mol, alkyl aluminum compound (c) is 1 to 20
It is preferable to use 0 mol, particularly 10 to 150 mol, and 1 to 50 mol, particularly 1 to 30 mol of the halogen-containing compound. When a catalyst having such a composition is used, a reaction result in which the selectivity of hexene is 90% or more and the ratio of 1-hexene to hexene is 99% or more can be easily obtained.

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. Particularly, as the reaction solvent, a chain saturated hydrocarbon having 4 to 10 carbon atoms or an alicyclic saturated hydrocarbon is preferable. 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, the temperature is usually from 30 to 250 ° C. and from 3 to 250 ° C.
The trimerization reaction is performed under the condition of 250 kg / cm ² .
Preferred reaction temperature and reaction pressure are 50 to 150, respectively.
° C, 5-100 kg / cm ² . The reaction time is generally 10 minutes to 10 hours, preferably 0.5 to 6 hours. Further, in the trimerization reaction, the molar ratio of 1-hexene to ethylene in the reaction solvent is 0.05 to 1.0, particularly 0.1 to 0.1.
It is preferable to carry out so as to be 10 to 0.80. That is, in the case of a continuous reaction, the catalyst concentration, the reaction pressure and other conditions are adjusted so that the molar ratio of ethylene and 1-hexene in the reaction solvent is within the above range. It is preferred that the reaction be stopped at a time when is within the above range. By doing so, by-products of components having a higher boiling point than 1-hexene are suppressed, and
Hexene selectivity is further increased.

The presence of hydrogen in the reactor generally improves the catalytic activity and trimer selectivity. Hydrogen abundance is 0.1-100 kg / cm ² as hydrogen partial pressure,
Particularly, 1 to 80 kg / cm ² is preferable. As an example of an embodiment of the present invention, a loop-type reactor 1 shown in FIG. 1 constituted by a tube having an inner diameter of 150 mm and having an internal volume of 370 liters is provided with a catalyst supply pipe 6 through 2,5-dimethylpyrrole. Of 13.8 mmol / hr. 92 mmol / hr of triethylaluminum. And hexachloroethane in 92
mmol / hr. Are continuously supplied as n-heptane solutions, respectively. From the other catalyst supply tube 7, 2.29 mmol / hr. Of chromium (III) 2-ethylhexanoate together with ethylene. (1.08 g / h
r. ), And continuously supplied as an n-heptane solution. The total feed of n-heptane to the reactor was 370 liters / hr. It is. The liquid in the reactor is circulated for 5
m / s while circulating ethylene at 145 kg / hr.
At 80 ℃, reaction stress 35kg
/ Cm ² G to perform a trimerization reaction of ethylene. The reaction solution is continuously withdrawn from the reactor via a downward withdrawing pipe 10.

When the ethylene trimerization reaction is carried out in this manner, the reaction can be continued for a long time, and the reaction can be carried out with a catalyst efficiency of 780,000 [g-1-hexene / g-chromium] and a polyethylene by-product amount of 0.08% by weight. Achieve results.

[Brief description of the drawings]

FIG. 1 is a conceptual diagram of one example of a loop reactor used in the present invention.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Reactor 2 Rise pipe 3 Downcomer pipe 4 Downward transition pipe 5 Upward transition pipe 6 Introducing pipe 7 Introducing pipe 8 Circulating means 9 Jacket 10 Downward extracting pipe 11 Upward extracting pipe 12 Valve 13 Valve

Claims (8)

[Claims] 1. When producing 1-hexene by trimerizing ethylene using a chromium-based catalyst, a loop reactor having an annular flow path is used, and a reaction containing ethylene and a catalyst is performed in the flow path. A method wherein the reaction is carried out while circulating the liquid. 2. The reactor according to claim 1, wherein the reactor has a jacket for temperature control along the annular flow path.
The described method. 3. The reactor according to claim 1, wherein the reactor has a circulation means for circulating the reaction solution in the annular flow path.
Or the method of 2. 4. The method according to claim 1, wherein the chromium-based catalyst comprises at least a combination of a chromium compound (a), a nitrogen-containing compound (b) and an alkylaluminum compound (c). Method. 5. The chromium-based catalyst comprises at least a combination of a chromium compound (a), a nitrogen-containing compound (b), an alkylaluminum compound (c) and a halogen-containing compound (d). 3. The method according to any one of 3. 6. The chromium-based catalyst comprises a chromium compound (a) 1
5. The method according to claim 4, wherein the compound is prepared using 1 to 50 mol of the nitrogen-containing compound (b) and 1 to 200 mol of the alkylaluminum compound (c) per mol. 7. The chromium-based catalyst comprises a chromium compound (a) 1
It is characterized by being prepared using 1 to 50 mol of the nitrogen-containing compound (b), 1 to 200 mol of the alkylaluminum compound (c) and 1 to 50 mol of the halogen-containing compound (d) per mol. 6. The method of claim 5, wherein 8. The method according to claim 1, wherein the molar ratio of 1-hexene to ethylene in the reaction solution is 0.05 to 1.0.