JP4809205B2 - An α-olefin dimerization catalyst and a method for producing an α-olefin dimer. - Google Patents

Description

  The present invention relates to an α-olefin dimerization catalyst.

Dimers or codimers of α-olefins typified by 4-methyl-1-pentene are used as monomers for producing polyolefins. Many basic catalysts have been conventionally proposed as a catalyst for producing a corresponding dimer or codimer by dimerization reaction or codimerization reaction of α-olefin. However, these catalysts have disadvantages such as low activity, insufficient selectivity to the target substance, and insufficient catalyst life even if the initial activity is high. Catalysts improved on these points have been proposed in JP-A-58-114737, JP-A-3-42043, JP-A-7-222927, and JP-A-2006-326418. There has been a demand for an improvement in selectivity, an improvement in selectivity, and an improvement in catalyst life (Patent Documents 1 to 4).
JP 58-114737 A JP-A-3-42043 Japanese Patent Laid-Open No. 7-222927 JP 2006-326418 A

  The object of the present invention is to propose an α-olefin dimerization catalyst having improved activity, selectivity and lifetime.

The present invention is as follows.
(1) an alkali metal (A), anhydrous potassium compound specific surface area measured by the BET method is 1.0m ² /g~3.0m ² / g (B), and the average particle diameter is 5μm~50μm A catalyst for dimerization of α-olefin, comprising graphite (C).
(2) The α-olefin according to (1), wherein the anhydrous potassium compound (B) is anhydrous potassium carbonate, and the alkali metal (A) comprises 80 g atom% or more of sodium metal (a). Catalyst for dimerization.
(3) Using the α-olefin dimerization catalyst according to (1) or (2), the α-olefin dimerization reaction or co-dimerization reaction is carried out by a gas phase method, a reaction temperature of 100 ° C. to 200 ° C. and A process for producing an α-olefin dimer, which is carried out at a reaction pressure of 1.96 MPa to 19.6 MPa .

  The catalyst for dimerization of α-olefin according to the present invention is industrially useful because the activity and selectivity of the catalyst are higher than those of conventional catalysts, the lifetime is long.

  The alkali metal (A), which is one of the constituent components of the catalyst of the present invention, comprises sodium metal (a) at 80 g atom% or more, preferably sodium metal (a) at 90 atom% or more. Here, the alkali metal is a metal that is not ionized.

  The content of alkali metal (A) in the α-olefin dimerization catalyst of the present invention is usually 0.5 to 10% by weight, preferably 1 to 5% by weight, based on the anhydrous potassium compound (B). is there. Here, the total amount of the alkali metal (A) and the anhydrous potassium compound (B) is 100% by weight.

Specific examples of the anhydrous potassium compound (B) in the present invention include anhydrous inorganic potassium compounds such as potassium carbonate, potassium silicate, potassium sulfate, potassium fluoride, potassium chloride, and potassium bromide. it can. Of these inorganic potassium compounds, anhydrous potassium carbonate is particularly preferred. Anhydrous potassium compound specific surface area measured by the BET method of (B) is, 1.0 m ² / g or more, preferably 1.0~5.0m ² / g, more preferably 1.0~3.0m ² / g It is. When the specific surface area of the anhydrous potassium compound (B) measured by the BET method is less than 1.0 m ² / g, the alkali metal (A) is not sufficiently supported on the anhydrous potassium compound (B), and the catalytic activity is decreased. Absent. When the specific surface area of the anhydrous potassium compound (B) measured by the BET method exceeds 3.0 m ² / g, the supported amount of the alkali metal (A) with respect to the anhydrous potassium compound (B) increases and the initial activity is high. However, it is not preferable in that the amount of by-products other than the intended dimerization product increases.

  The form of the α-olefin dimerization catalyst of the present invention may be a powder, a tablet, a cylinder (pellet), a sphere, or the like. However, the catalyst activity and the desired dimerization product are selected. In order to improve the property, the catalyst life, and the like, a form formed into a tablet shape, a cylindrical shape (pellet shape), a spherical shape or the like is preferable. When the form of the α-olefin dimerization catalyst is formed into a tablet shape, a cylindrical shape (pellet shape), a spherical shape, or the like, graphite (C) is included as an essential component.

When the α-olefin dimerization catalyst of the present invention contains graphite (C) as an essential component, the specific surface area of the graphite (C) measured by the BET method is 0.1 to 300 m ² / g, preferably 1 ~200m more preferably ² / g is 1 to 50 m ² / g. If the specific surface area of the graphite (C) measured by the BET method is less than 0.1 m ² / g, the catalyst prepared from this support has a short life, which is not preferable. If the specific surface area of graphite (C) measured by the BET method exceeds 300 m ² / g, it is difficult to obtain a strong support of the catalyst prepared from this support. Graphite (C) includes natural graphite and artificial graphite, but any of them may be used. The average particle diameter of graphite (C) is preferably 500 μm or less, more preferably 100 μm or less, and further preferably 5 to 50 μm.

  When the α-olefin dimerization catalyst of the present invention contains graphite (C) as an essential component, the content of graphite (C) is 0.1 to 3% by weight with respect to the anhydrous potassium compound (B), preferably 0.6 to 2% by weight. Here, the total amount of anhydrous potassium compound (B) and graphite (C) is 100% by weight. In the case where the content of graphite (C) is less than 0.1% by weight, the catalyst life and the selectivity to dimerization of α-olefin are lowered. Further, even if the content of the graphite (C) is larger than 3% by weight, the catalytic activity and the selectivity of the dimerization product are no longer improved, and the strength is high when compression molding. It is difficult to obtain a support, and a catalyst prepared from this support has a short life and is not preferable.

  When the form of the α-olefin dimerization catalyst of the present invention is formed into a tablet shape, a cylindrical shape (pellet), a spherical shape or the like, a compression-molded granular carrier (X) containing an anhydrous potassium compound (B) and graphite (C) ) And then supporting the alkali metal (A) is preferred for improving catalytic activity and selectivity to the desired dimerization product.

  The catalyst of the present invention can be prepared by various methods. First, the compression-molded granular carrier (X) constituting the catalyst of the present invention can be usually prepared by the following method.

  The compression-molded granular carrier comprising the graphite (C) and the anhydrous potassium compound (B), and compression-molding a powdery composition having a specific composition with a tableting machine, a compression molding machine, a pelletizer or the like. (X) is obtained. The shape of the compression-molded granular carrier may be any shape, but it is usually formed into a tablet shape, a cylindrical shape (pellet shape), a spherical shape, and the particle size is usually 0.5 mm or more, preferably Is in the range of 1 to 10 mm.

  The catalyst of the present invention is prepared by supporting the supporting component on the compression-molded granular carrier (X) prepared by the above method. Various methods can be adopted as a method of supporting the compression-molded granular carrier (X). Here, in any case, when sodium metal (a) is used as the alkali metal of the supporting component, this sodium metal (a) is contacted with the anhydrous potassium compound (B) under heating, whereby the alkali metal exchanges. Is generated, and a potassium metal and an anhydrous sodium compound are produced. Therefore, the composition of the alkali metal (A) composed of the sodium metal (a) and the potassium metal (b) in the supported catalyst component after the preparation is preferable in the present invention. It is preferable to prepare so that it may become a range. Therefore, as the alkali metal component before loading, sodium metal can be used alone, or it can be used as an alloy of sodium metal and potassium metal. Specific examples of the loading method include the following methods.

(1) A method in which sodium metal and the compression-molded granular carrier (X) are brought into contact under heating and stirring in an inert gas atmosphere.
(2) A method in which a mixture of sodium metal and, if necessary, other supporting components and the compression-molded granular carrier (X) are brought into contact with each other under heating and stirring in an inert gas atmosphere.

  Here, the temperature during the supporting treatment is usually in the range of 150 ° C. to 400 ° C., but in order to obtain a catalyst having excellent catalytic activity, catalyst life and selectivity to the dimerization product, it is 200 to 350 ° C. The supporting treatment is preferably performed at a temperature in the range.

  The catalyst of the present invention is used for an α-olefin dimerization reaction or co-dimerization reaction. Specific examples of the α-olefin include lower α-olefins such as ethylene, propylene, 1-butene, isobutylene and 1-pentene. Among these dimerization reactions or co-dimerization reactions, production of 4-methyl-1-pentene by dimerization of propylene, production of 3-methyl-1-pentene by co-dimerization of 1-butene and ethylene, Preference is given to using the catalyst according to the invention.

The α-olefin dimerization reaction or co-dimerization reaction using the catalyst of the present invention is carried out by heating in a gas phase method or a liquid phase method, but is preferably carried out by a gas phase method. The temperature when the reaction is carried out by a gas phase reaction is usually 0 to 300 ° C., preferably 100 to 200 ° C. The pressure during the reaction is usually in the range of normal pressure to 19.6 MPa (200 kg / cm ² -G), preferably 1.96 to 14.7 MPa (20 to 150 kg / cm ² -G). The reaction can be carried out in a fixed bed system or a fluidized bed system, but is preferably carried out in a fixed bed system. When the reaction is carried out in a fixed bed system, alpha-olefin liquid hourly space velocity (LHSV) to normally 0.1 to 10 hr ^-1, preferably in the range of from 0.5 5 hr ^-1. Unreacted α-olefin and product are separated from the mixture after completion of the reaction according to a conventional method, and the unreacted α-olefin is recycled in the reaction.

Hereinafter, the present invention will be specifically described by way of examples, but the present invention is not limited thereto.
[Example 1]
(1) Preparation of catalyst 1% by weight of graphite having an average particle diameter of 19 μm and a specific surface area measured by the BET method of 10 m ² / g, a specific surface area of 1.2 m ² / g measured by the BET method, and a bulk density of 0.1%. A carrier containing 94 g / ml of anhydrous potassium carbonate 99% by weight was tableted and molded into a cylindrical shape having a diameter of 3.2 mm and a height of 3.2 mm. 9.65 g of this support was dried in a nitrogen stream at 260 ° C. for 3 hours, 0.35 g of sodium was added over 1.5 hours in a nitrogen atmosphere, and the mixture was stirred at 280 ° C. for 2 hours to prepare a catalyst.

(2) Dimerization reaction The dimerization reaction of propylene was performed using the catalyst prepared in the above (1). A pressure-resistant liquid phase reactor equipped with a rotor was filled with a catalyst and propylene. The pressure and temperature of the reactor decreased from 7.5 MPa and 127 ° C., and the reaction was started. When the reaction was continued while gradually raising the temperature with the consumption of propylene, it was 140 ° C. and a maximum of 8.6 MPa. Thereafter, the pressure gradually decreased, and the pressure when 8 hours passed was 6.2 MPa. As a result of analyzing the reaction product, the conversion of propylene was 7.52% and the selectivity of 4-methyl-1-pentene was 88.58%. Further, the original catalyst retention after the reaction was 77%. The prototype retention rate is a value obtained by dividing the number of unbroken catalysts when the catalyst is removed from the reaction tube after the reaction by the number of the pre-reaction catalyst filled in the reaction tube and multiplying by 100. The results are listed in Table 1.

[Example 2]
A catalyst was prepared in the same manner as in Example 1, except that the shape of the carrier was formed to a diameter of 5.0 mm and a height of 3.2 mm, and 9.50 g of this carrier was added with 0.50 g of sodium in a nitrogen atmosphere. A dimerization reaction of propylene was performed. The conversion of propylene was 9.31% and the selectivity for 4-methyl-1-pentene was 83.25%. Further, the catalyst original retention rate was 100%.

[Comparative Example 1]
A catalyst was prepared in the same manner as in Example 1 except that anhydrous potassium carbonate having a specific surface area measured by the BET method of 0.35 m ² / g was used, and propylene dimerization reaction was performed. The conversion of propylene was 4.20%, and the selectivity for 4-methyl-1-pentene was 82.81%. Further, the catalyst original retention rate was 100%. The results are listed in Table 1.

  By using the method of the present invention, a catalyst having high activity and selectivity and a long life can be prepared.

Claims (3)

And alkali metal (A), Brunauer-Emmett- Teller Method: The specific surface area measuring method (hereinafter BET method substantially to) anhydrous potassium compound measured specific surface area of 1.0m ² /g~3.0m ² / g by An α-olefin dimerization catalyst comprising (B) and graphite (C) having an average particle diameter of 5 μm to 50 μm.   2. The α-olefin dimerization according to claim 1, wherein the anhydrous potassium compound (B) is anhydrous potassium carbonate, and the alkali metal (A) comprises 80 g atom% or more of sodium metal (a). catalyst. Using the α-olefin dimerization catalyst according to claim 1 or 2, the α-olefin dimerization reaction or co-dimerization reaction is carried out by a gas phase method, a reaction temperature of 100 ° C. to 200 ° C. and a reaction pressure of 1 A process for producing an α-olefin dimer, which is performed at 96 MPa to 19.6 MPa .