JPS5940504B2 - Catalyst for α-olefin dimerization - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a catalyst for dimerization or co-dimerization of α-olefins.

More specifically, the present invention relates to a catalyst that is highly active in the dimerization or co-dimerization reaction of α-olefins and can be used for a long period of time without deteriorating its activity.
Dimers or codimers of α-olefins, typified by 4-methyl-1-pentene, are used as monomers for producing polyolefins.

Many basic catalysts have hitherto been proposed as catalysts for producing the corresponding dimers or codimers by dimerization or codimerization reactions of α-olefins.

However, most of these catalysts have drawbacks such as low activity, insufficient selectivity toward the desired product, or short catalyst life even if the initial activity is high, and they cannot be used on an industrial scale. There are few methods that can be effectively used in implementation. Among these basic catalysts that have been proposed in the past, catalysts in which sodium metal is dispersed in granular anhydrous potassium compounds are disclosed in Japanese Patent Publication No. 42-22474, Japanese Patent Publication No. 43-25344, and Japanese Unexamined Patent Application Publication No. 1987-55. It is disclosed in Japanese Patent Laid-Open No. 145533-14553 and Japanese Patent Application Laid-open No. 145534-1987. In particular, among these proposals, the
Publication No. 474 shows an example in which granular potassium carbonate containing a small amount of graphite is used as a granular anhydrous potassium compound as a carrier, but all of these catalysts have poor catalytic activity and selectivity to the desired product. It is also advantageous in terms of ease of preparation and handling during industrialization, but since the catalyst activity decreases in a relatively short period of time, the catalyst must be replaced frequently. Furthermore, among the basic catalysts that have been proposed in the past, catalysts in which an alkali metal is supported on a type of carrier other than the above-mentioned anhydrous potassium compound have been proposed. For example, attempts have been made to use a catalyst in which an alkali metal is supported on a carbon carrier such as graphite as a dimerization catalyst for α-olefin.
No. 2,822, No. 912,823, No. 932,342
However, similar to the above, these catalysts do not have sufficiently high catalytic activity, catalyst life, or selectivity to the target dimerization product, and cannot be used on an industrial scale. It has not been. Therefore, in any case, it is a challenge to improve the catalytic activity and extend the active life of a catalyst in which an alkali metal is supported on a carrier. Similarly, in the method using catalytic converters, the biggest challenge is to improve the catalytic activity and to suppress the decrease in the activity. The present invention was made in view of the above-mentioned current situation, and its object is to provide a catalyst for dimerization or co-dimerization of α-olefins that is highly active, highly selective to the target product, and has a long life. Our goal is to provide the following.

The present invention is based on the discovery that the above object can be achieved by using a catalyst in which an alkali metal mixture of a specific composition is supported on a compression-molded granular carrier containing anhydrous potassium carbonate having specific properties as a main component. It is. To summarize the present invention, the present invention provides a catalyst in which an alkali metal prisoner is supported on a carrier film containing anhydrous potassium carbonate as a main component, (1) the alkali metal prisoner contains sodium metal (a) and potassium metal (b). (4) the carrier is carbon ( c) and anhydrous potassium carbonate (d), and the content of the carbon (c) is in the range of 0.8 to 3% by weight based on the anhydrous potassium carbonate (d). This is a catalyst for dimerization of α-olefin, which is characterized by the following.

The alkali metal prison, which is one of the constituent components of the catalyst of the present invention, consists of a mixture of sodium metal (a) and potassium metal (b), and its composition is sodium metal (a) 2
in the range of 0 to 90 gram at% and potassium metal
b) Must be comprised in the range of 10 to 80 gram at%.

The composition ratio of sodium metal among the alkali metals is 90
When the composition ratio of potassium metal becomes larger than 10 gram at % and less than 10 gram at %, the catalytic activity and selectivity to dimerization products decrease, and in particular, the induction period until the maximum activity is shown decreases. becomes noticeably longer. Further, when the composition ratio of sodium metal becomes less than 20 g at % and the composition ratio of potassium metal becomes more than 80 g at %, the initial activity of the catalyst becomes high, but the activity decreases significantly and the catalyst life becomes short. Furthermore, the composition of the alkali metal mixture is in the range of 30 to 85 gram at% of sodium metal (a) and 15 to 7 of potassium metal (b).
A content in the range of 0 g at % is preferable because a catalyst with excellent catalyst activity, catalyst life, and selectivity to the desired dimerization product can be obtained. If necessary, other components may be added to this alkali metal mixture to form a supporting component. The proportion of the alkali metal mixture in the supported components on the carrier 8 is usually 0.5 to 10% by weight, preferably 1 to 5% by weight based on the anhydrous potassium carbonate (d) as a component of the carrier. % range.

The carrier 8, which is another component of the catalyst of the present invention, is a carrier mainly composed of anhydrous potassium carbonate, and more specifically, a compression-molded granular carrier composed of carbon (c) and anhydrous potassium carbonate (d). It is a carrier. The carbon (
The content of c) is 0 relative to the anhydrous potassium carbonate (d).
．． It is necessary that the content be in the range of 8 to 3% by weight. When the content of carbon (c) in the carrier 8 is 0.8% by weight or more, it is 0.5% by weight as described in conventional known literature.
The catalyst life and the selectivity to the dimerization product of α-olefin are significantly improved compared to the case of . Also,
Even if the content of carbon (c) is greater than 3% by weight,
In addition to the fact that both the catalytic activity and the selectivity towards dimerization products are no longer improved, it becomes difficult to obtain a strong support when compression molded, and the lifetime of the catalyst prepared from this support is shortened. Therefore, it cannot be used on an industrial scale. The carbon (
The content of c) is 0 relative to the anhydrous potassium carbonate (d).
．． Preferably it is in the range of 8 to 2% by weight. In addition, anhydrous potassium carbonate (d), which is a component of the carrier 8 of the catalyst of the present invention, is ordinary anhydrous potassium carbonate, but the catalytic activity is
A catalyst with further improved catalyst life and selectivity to the desired dimerization product. In order to obtain this, it is preferable to use a carrier obtained by compression molding raw powder of anhydrous potassium carbonate having appropriate properties.

Specific examples of carbon (c) which is a component of the compression-molded granular carrier 8 constituting the catalyst of the present invention include graphite, amorphous carbon, and the like.

Among these carbons, graphite is preferably used. As mentioned above, the essential supporting components constituting the catalyst of the present invention include sodium metal (a) and potassium metal (b).
), but if the composition is within the scope of the present invention, the supporting component may include a mixture containing other components as necessary in addition to the essential alkali metal mixture. It may also be supported as

Here, when the supported component consists only of the alkali metal mixture, it is a liquid or solid material consisting of a sodium-potassium alloy, but when the supported component is a mixture of the alkali metal mixture and the other components, it is in the form of a paste. It is.

The catalyst of the present invention can be prepared by various methods.

First, the compression-molded granular carrier film constituting the catalyst of the present invention is:
It can usually be prepared by the following method. By compression molding a powdered composition consisting of the carbon (c) and the anhydrous potassium carbonate (d) and having a specific composition using a tablet molding machine, a compression molding machine, a pelletizer, etc. A compression-molded granular carrier 8 is obtained.

The shape of this compression-molded granular carrier may be any shape, but it is usually formed into a tablet, pellet, or spherical shape, and the particle size is usually 0.5ml or more, preferably 1 to 10ml. This is within the scope of the matter. The catalyst of the present invention is prepared by supporting the above-mentioned supported components on the compression-molded granular carrier 8 prepared by the above-mentioned method.

Various methods can be employed to support the above-mentioned supporting components on the compression-molded granular carrier web. In either case, when sodium metal (a) is used as the alkali metal of the supported component, this sodium metal (
When a) comes into contact with anhydrous potassium carbonate (d) under heating, the alkali metal undergoes an exchange reaction and produces potassium metal and anhydrous sodium carbonate. ) and potassium metal (b) must be adjusted to fall within the scope of the present invention. Therefore, as the alkali metal component before being supported, sodium metal can be used alone, or an alloy of sodium metal and potassium metal can be used. Specifically, the following method can be exemplified as the supporting method. (1) A method in which sodium metal and the compression-molded granular carrier film are brought into contact with each other under heating and stirring in an inert gas atmosphere.

(2) A method in which a mixture of sodium metal and optionally other supported components is brought into contact with the compression-molded granular carrier film under heating and stirring in an inert gas atmosphere.

A method in which an alloy of trisodium metal and potassium metal and the compression-molded granular carrier are brought into contact with each other under heating and stirring in an inert gas atmosphere.

(4) A method of bringing a mixture consisting of an alloy of sodium metal and potassium metal and other supported components as necessary into contact with the compression-molded granular carrier circle in an inert gas atmosphere while heating and stirring. The temperature during the supporting treatment is usually in the range of 150 to 400°C, but in order to obtain a catalyst with excellent catalytic activity, catalyst life, and selectivity to dimerization products, it is necessary to set the temperature in the range of 200 to 350°C. Preferably, the supporting treatment is carried out at temperature.

Conventionally known α-olefin dimerization catalysts have been commonly used in areas where the conversion rate of α-olefin is high, but their drawbacks are that the activity of the catalyst is significantly reduced, and it is difficult to reduce the conversion rate of α-olefin. However, even if the catalyst was used, it was not possible to significantly reduce the activity of the catalyst and improve the selectivity to dimerized products.

In contrast, compared to any conventionally known catalyst, the catalyst of the present invention not only suppresses the decrease in activity even in the region where the conversion rate of α-olefin is high, but also is low, especially when the rate of change of α-olefin is 5.
In the range of 0% or less, the decrease in catalyst activity is significantly suppressed, the catalyst life is long, and the selectivity to dimerization products is high. The catalyst of the present invention is used in the dimerization reaction or co-dimerization reaction of α-olefin.

Specific examples of α-olefins include lower α-olefins such as ethylene, propylene, 1-butene, isobutylene, and 1-benzene. Among these dimerization reactions or co-dimerization reactions, production of 4-methyl-1-benzene by dimerization of propylene, production of 3-methyl-1-benzene by co-dimerization of 1-butene and ethylene,
Preference is given to using the catalyst of the invention for the production of 2-methyl-1-benzene by co-dimerization of isobutylene and ethylene, in particular for the production of 4-methyl-1-benzene by co-dimerization of propylene.
Preference is given to using the catalyst of the invention for the production of 1-benzene. The dimerization reaction or co-dimerization reaction of α-olefin using the catalyst of the present invention is carried out by a gas phase method or a liquid phase method under heating, but it is preferably carried out by a gas phase method.

The temperature when carrying out the reaction by the gas phase method is usually between o and 300 °C.
℃, preferably 100 to 0.5℃. The temperature is 200°C. The pressure during the reaction is usually normal pressure 200kg/Cd-
G, preferably in the range of 150kg/CrlL-G. The reaction can also be carried out in a fixed bed method,
Although it can be carried out using a fluidized bed method, it is preferable to use a fixed bed method. When the reaction is carried out in a fixed bed mode, the liquid hourly space velocity (LHSV) of the α-olefin is generally in the range of 0.1 to 10 hr−1, preferably 0.5 hr−1. After completion of the reaction, unreacted α-olefin and product are separated from the mixture according to a conventional method, and unreacted α-olefin and product are separated from the mixture.
The olefin is recycled to the reaction. EXAMPLES Next, the method of the present invention will be specifically explained using Examples, but the present invention is not limited thereto. The physical properties of the carrier and supported catalyst shown in the examples were measured as follows.

(1) Measurement of particle size distribution of raw powder of anhydrous potassium carbonate Combine JIS standard standard sieves from 16 mesh to 200 mesh, put a sample of raw powder of anhydrous potassium carbonate of about 150 I on top of the sieves, and place the whole into a polyethylene sieve. Put it in a bag and seal it.

This sieve was set in a low-tap type vibrating sieve shaker (19-45 manufactured by Kurihara Seisakusho), and sieved for 10 minutes under the conditions of shaking at 290 times/min and hammering at 156 times/min. The weight of the anhydrous potassium carbonate on each sieve after sieving was measured, the weight percentage was calculated, and the average particle size was determined from the RRS diagram. (2) Measurement of pore volume ratio of carrier Using approximately 101 carrier samples that had been heat-dried at 300°C for 2 hours, the specific gravity of the carrier was measured in mercury and carbon tetrachloride at 40°C. The ratio of the pore volume to the volume of the pore volume was determined as a volume percentage using the following formula as the pore volume ratio.

Here, DHfl and DCCl4 represent the specific gravity of the carrier measured in mercury and carbon tetrachloride, respectively; L/,,ρ
Hθ and f) COl4 represent the densities of mercury and carbon tetrachloride at 40°C, respectively. (3) Measurement of graphite content in the carrier 100 ml of water and 20 ml of methanol were added to 50 g of the carrier sample, which had been heated and dried at 300°C for 2 hours in advance.
After stirring with a magnetic stirrer for 20 minutes,
Further, the mixture was stirred for 30 minutes using an ultrasonic cleaner.

The liberated graphite was washed with water, dried at 100° C. for 2 hours, and its weight was measured and expressed as a percentage by weight relative to the anhydrous potassium carbonate in the carrier. (4) Measurement of supported alkali metal component composition About 2 g of the supported catalyst was accurately weighed, and 15 ml of water was added in a nitrogen atmosphere.
was added, and the amount of hydrogen gas generated was measured using a gas bottle.

The temperature at the time of measurement is TCO, the pressure is P (MmH9), TCc
) is the partial pressure of water at PH2O (MmH9), the amount of gas generated is V (g), the amount of alkali metal metal supported in the measured supported catalyst M (g) is A (fl), and the carbon content is C ( g)
The values of A and B were determined from the following formula, assuming that the amount of alkali metal supported on anhydrous potassium carbonate 1001 was B (9 atoms). On the other hand, 50 ml of anhydrous isopropyl alcohol was added to 2 g of the supported catalyst in a nitrogen atmosphere, and after the mixture was left to stand at room temperature for 1 hour, the carrier and other solids were centrifuged.

The amounts of sodium alkoxide and potassium alkoxide eluted into the isopropyl alcohol thus obtained were measured by atomic absorption spectrometry, and the Na/K ratio was determined from both values. In addition, the amount of Na and the amount of K with respect to anhydrous potassium carbonate 1009 in the supported alkali metal component constituting the supported catalyst are the previously determined value of the supported alkali metal amount B (9 atoms) with respect to anhydrous potassium carbonate 1009 and the Na/K ratio. It was calculated from the value of by the following formula.

(5) Measurement of bulk density of raw powder of anhydrous potassium carbonate It has a sample drop opening at the lower end and its inner diameter is 26.5 mm) The inner diameter at the upper end is 94 mm, the height is 100 m7n, and the internal volume is 150 m1. A certain funnel was fixed vertically so that the height from the bottom end of the funnel to the sample drop opening was 100 mm.

A cylindrical receiver with an inner diameter of 39 WLm, a height of 81 mm, and an internal volume of 98.0 m1 was placed directly below the sample droplet of this funnel. Anhydrous potassium carbonate sample powder was placed in the funnel, a sample drop opening at the bottom was opened, and the sample powder was dropped into the receiver. The raised sample at the top of the receiver was ground horizontally. The weight of the sample in the receiver was measured and the bulk density was determined. Other physical properties were measured by conventional methods.

Example 1 (1) Preparation of catalyst Particle size with an average particle size of 450μ, 0.5% by weight of particles with a particle size of less than 100μ, and 27.6% by weight of particles with a particle size of more than 600μ and up to 1000μ using anhydrous potassium carbonate with a bulk density of 1.1 g/ml,
A cylindrical carrier with a diameter of 3 mm and a height of 3 mm containing 1.0% by weight of graphite based on anhydrous potassium carbonate was compressed into tablets.

After drying 97.5 g of this carrier at 350° C. for 2 hours in a nitrogen stream, 2.5 g of sodium was added under a nitrogen atmosphere, and the mixture was stirred at 230° C. for 5 hours to prepare a catalyst.

The physical properties of the carrier and supported catalyst are shown in Table 1 below together with the results of each example. (2) Dimerization reaction A propylene dimerization reaction was carried out using the catalyst prepared in (1) above.

A pressure-resistant gas phase reactor was filled with a catalyst, and propylene was heated at a liquid hourly space velocity (LHSV) of 0.85 hr- while maintaining the reactor pressure at 100 kg/11 G and temperature at 157°C.
The reaction was carried out continuously. As a result, the propylene conversion rate reached a maximum of 83% after 5 hours, and then decreased to almost zero. The half-life of maximum activity, ie, the time required for the maximum conversion of propylene to be halved, was 1800 hours. In addition, 4-methyl-1 in the hexene fraction of the product
-The content of benzene was 92%. Example 2 The same procedure as in (2) of Example 1 was carried out except that the catalyst prepared in the mountain of Example 1 was used and the dimerization reaction of propylene was carried out under the conditions of LHSV 2.7 Ohr-1150°C. .

The results are shown in Table 1. Comparative Example 1 The catalyst shown in Table 1 was obtained by changing the loading conditions for sodium in Example 1 (1).

Using this catalyst, a propylene dimerization reaction was carried out under the same conditions as in Example 2. The results are shown in Table 1. Examples 3 and 4, Comparative Examples 2 and 3 In (1) of Example 1, the graphite content was 1.5% by weight (Example 3) and 2.0% by weight (Fb (Example)) based on potassium carbonate. 4), 0.5% by weight (Comparative Example 2)4.
The carrier shown in Table 1 containing 0% by weight (Comparative Example 3) was compressed into tablets.

Using these carriers, the catalysts shown in Table 1 were obtained by preparing according to the method (1) of Example 1.

Using this catalyst, a propylene dimerization reaction was carried out under the same conditions as in Example 2.

The results are shown in Table 1.

Example 5, Comparative Example 4 In (1) of Example 1, Table 1 shows that the graphite content is 0.8% by weight (Example 5) and 0.6% by weight (Comparative Example 4) with respect to potassium carbonate. The carrier shown in 1 was compressed into tablets.

Using these carriers, the catalysts shown in Table 1 were obtained by preparing according to the method described in Example 1 (7) and (1).

Using this catalyst, a propylene dimerization reaction was carried out under the same conditions as in Example 2.

The results are shown in Table 1. As is clear from Table 1 above, the catalyst of the present invention has particularly remarkable effects on catalyst activity, catalyst life, and selectivity to dimerization products compared to the catalyst of the comparative example.

Claims (1)

[Scope of Claims] 1. A catalyst in which an alkali metal [A] is supported on a carrier [B] whose main component is anhydrous potassium carbonate, in which (i) the alkali metal [A] is a sodium metal (a) and a potassium metal; (b) having a composition consisting of 20 to 90 gram at % of sodium metal (a) and 10 to 80 gram at % of potassium metal (b); and (ii) said carrier [B ] is composed of carbon (c) and anhydrous potassium carbonate (d), and the carbon (c
) content is 0.8 with respect to the anhydrous potassium carbonate (d)
A catalyst for the dimerization of α-olefins, characterized in that it is a compression-molded granular carrier in the range of 3% to 3% by weight. 2 The carrier [B] is 0.8 to anhydrous potassium carbonate.
A catalyst according to claim 1, which is a compression-molded granular support containing carbon in the range from 2% to 2% by weight. 3 The composition of the alkali metal [A] is sodium metal (
a) in the range of 30 to 85 gram at % and potassium metal (b) in the range of 15 to 70 gram at %;
The catalyst according to claim 1 or 2, wherein the alkali metal is supported in a proportion of 1 to 5% by weight based on the anhydrous potassium carbonate (d). 4. The catalyst according to any one of claims 1 to 3, wherein the carbon (c) is graphite.