JPH07289908A - Production of alpha-olefin dimerizing catalyst - Google Patents

Abstract

PURPOSE:To obtain an alpha-olefin dimerizing catalyst excellent in activity and capable of especially improving the selectivity of an objective product and reduced in the lowering of mechanical strength during use. CONSTITUTION:In a method for producing an alpha-olefin dimerizing catalyst by supporting alkali metal on a compression molded granular carrier, the compression molded granular carrier is obtained by subjecting a mixture (a) consisting of an anhydrous potassium compd., carbon and a thermally decomposable org. binder whose amt. is 4-20wt.% with respect to the total wt. of the carrier to compression molding and subsequently baking the compression molded object (b) to thermally decompose the thermally decomposable org. binder.

Description

Detailed Description of the Invention

[0001]

FIELD OF THE INVENTION The present invention relates to a process for producing an α-olefin dimerization or codimerization catalyst. More specifically, it relates to a method for producing an α-olefin dimerization catalyst which has excellent activity and selectivity, and in which mechanical strength is not significantly reduced particularly under reaction conditions.

[0002]

2. Description of the Related Art As a catalyst for producing a dimer or a co-dimer of a lower α-olefin, many catalysts in which an alkali metal is supported on a support have been proposed. Among these catalysts, it is advantageous to use a compression-molded granular carrier as a support for carrying out on an industrial scale. However, most of such catalysts have low activity and low selectivity, or even high activity is selected. There are some drawbacks such as low rate, and few of them can be used effectively. Also,
Since the conventional catalyst has low mechanical strength during use and is easily pulverized in a relatively short period of time, improvement thereof has been strongly desired.

As the compression-molded granular catalyst, a catalyst in which metallic sodium is supported on a compression-molded granular carrier composed of anhydrous potassium carbonate and carbon is disclosed in JP-B-59-40503 and JP-B-59-59.
-40504, JP-B-59-40506, JP-A-3-42043
It is disclosed in the publication. Further, Japanese Patent Publication No. 59-40505 discloses a catalyst in which a mixture of metallic sodium, potassium carbonate and carbon is carried on a compression molded granular carrier comprising anhydrous potassium carbonate and carbon. In the propylene dimerization reaction using these catalysts, the desired product, 4-
The selectivity of methylpentene-1 is relatively good at 90-93%, but it is not yet high enough. Japanese Unexamined Patent Publication No. 62-38240 discloses a catalyst obtained by oxidizing a pellet made of potassium carbonate and carbon and carrying metal potassium on the pellet.
No. 4727213 has potassium carbonate, calcium aluminate,
A catalyst in which metal potassium is supported on a pellet made of carbon,
U.S. Pat.No. 4,835,330 discloses potassium carbonate, a catalyst in which glass powder and metallic potassium are supported on carbon pellets, but the selectivity of 4-methylpentene-1 is low,
It had the disadvantage that it was only 90% at maximum.

Several proposals have been made for improving the mechanical strength of the catalyst under the reaction conditions. JP 61-462
Japanese Patent Publication No. 48 discloses a catalyst in which potassium carbonate particles carry stainless powder and metallic potassium. Although the physical properties are said to be improved, after 30 hours of reaction,
It is described that the catalyst layer is not clogged, or even if it is present, it is only moderately clogged. Although considerable pulverization and embrittlement are expected, no evaluation of its physical properties has been observed. The same applies to a catalyst obtained by supporting stainless steel powder and metallic potassium on an extruded product of potassium carbonate (JP-A-1-207137). It is only described that the appearance of the catalyst is good after 7.5 hours, or that some fine particles are observed.

Japanese Unexamined Patent Publication (Kokai) No. 3-42043 discloses a catalyst in which sodium carbonate raw powder having high porosity is used, and metallic sodium is supported on a compression-molded granular carrier made of carbon and carbon powder. Although there is a statement that the mechanical strength is significantly improved, no specific data is given for that, only the degree of pressure drop increase during the reaction is described. No mention is made of any change in mechanical strength, despite the considerable pulverization of the catalyst.

[0006] As described above, most of the conventional catalysts have low mechanical strength during use and are powdered in a relatively short period of time. In addition to the fact that the catalyst must be replaced, there is a major industrial drawback that it is difficult to take out the used catalyst due to clogging of the catalyst layer.

[0007]

SUMMARY OF THE INVENTION The object of the present invention is α
-In olefin dimerization or co-dimerization, it is possible to improve the selectivity to a target product while maintaining the activity, and to provide a method for producing a catalyst with little decrease in mechanical strength during use. is there.

[0008]

The present invention provides a method for producing an α-olefin dimerization catalyst in which an alkali metal is supported on a compression-molded granular carrier, wherein the compression-molded granular carrier is:
(a) A mixture consisting of an anhydrous potassium compound, carbon, and 4 to 20% by weight of a pyrolyzable organic binder, based on the total weight of the carrier, is compression molded, and (b) the compression molded product is then fired to heat it. The present invention relates to a method for producing an α-olefin dimerization catalyst, which comprises using a compression-molded granular carrier obtained by thermally decomposing a decomposable organic binder.

In the present invention, potassium fluoride, potassium carbonate, or a mixture of potassium fluoride and potassium carbonate can be used as the anhydrous potassium compound. Potassium fluoride is preferable because it has a high effect of improving the selectivity of the target product. Further, the use of a mixture of potassium fluoride and potassium carbonate is more preferable because the alkali metal supporting property is further improved.

The mixing ratio of potassium fluoride and potassium carbonate is not particularly limited, but potassium fluoride is in the range of 10 to 80% by weight and potassium carbonate is 90 to 20% by weight based on the total weight of the anhydrous potassium compound. It is preferably in the range of.
Further, it is particularly preferable that potassium fluoride is in the range of 20 to 70% by weight and potassium carbonate is in the range of 80 to 30% by weight. The catalyst having the above range is more excellent in the selectivity of the target product and the supportability of sodium metal.

As an anhydrous potassium compound, in addition to potassium fluoride and potassium carbonate, a small amount of potassium halides such as potassium chloride, potassium bromide and potassium iodide, potassium sulfate, potassium nitrate, potassium silicate, potassium silicofluoride and the like are contained. You may.

The thermally decomposable organic binder is not particularly limited, but examples thereof include starch, dextrin, crystalline cellulose, carboxymethyl cellulose, polyvinyl alcohol and the like. Among them, crystalline methyl cellulose is particularly preferable because it is excellent in catalytic activity, selectivity and maintenance of mechanical strength. The shape is preferably fine powder.

The amount of the thermally decomposable organic binder used is 4 to 20% by weight, preferably 5 to 17% by weight, based on the total weight of the carrier.
More preferably, it is in the range of 6 to 14 wt%. Below 4 wt%, the activity and selectivity are good, but it is difficult to maintain the mechanical strength during the reaction. When the content is 20 wt% or more, the mechanical strength during the reaction is high, but the activity and the strength during molding are difficult to maintain, and the strength tends to decrease due to burning and burning.

In the present invention, the thermally decomposable organic binder plays a major role in maintaining the mechanical strength of the catalyst. When a compression-molded granular carrier composed of an anhydrous potassium compound, carbon and a thermally decomposable organic binder is fired, a large number of pores formed by burning off the organic binder have a great effect on maintaining mechanical strength during the reaction. The purpose of the binder used in the conventional carrier is to increase the molding strength and provide shape retention, but in the present invention, a binder is used, but by burning and burning it, a sparse structure is obtained. It has the effect of giving a compression molded body. Moreover, the strength of the compression-molded body is not deteriorated even by the burning and burning treatment. In the propylene dimerization reaction, for example, H. Pines, Synthesis, 309
(1974), the active species of the reaction is allyl potassium (C
₃ H ₅ K). The compression-molded carrier of the present invention having a sparse structure has an effect that it does not expand and fracture even if allyl potassium and other organic potassium compounds are produced and grown in the pores during the reaction.

Specific examples of the alkali metal used in the present invention include sodium, potassium and a mixture thereof. In general, the reaction activity of sodium metal is considerably lower than that of potassium metal,
By contacting sodium metal with potassium fluoride or potassium carbonate under heating, sodium metal easily undergoes an exchange reaction to produce sodium fluoride or sodium carbonate and potassium metal. It is also possible to use sodium metal alone.
In particular, in the present invention, the catalyst using sodium as the alkali metal component before loading has a remarkable selectivity improving effect.

The amount of the alkali metal used is not particularly limited, but is preferably 1 to 10% by weight, based on the total weight of the catalyst.
1.5 to 6% by weight is preferred. Generally, increasing the amount of the alkali metal supported increases the production rate per unit weight of the catalyst, which is industrially advantageous, but it is difficult to remove heat even if the amount is excessively increased, or the selectivity decreases. It is not preferable.

The carbon used in the present invention is activated carbon,
Examples include graphite and carbon black. These carbons may be used alone or in a mixture of two or more. Particularly, graphite can be preferably used.

In the present invention, the amount of carbon used is not particularly limited, but is preferably 0.2 to 3.0% by weight based on the total weight of the catalyst.

In the present invention, carbon, an anhydrous potassium compound raw powder, and a thermally decomposable organic binder powder are thoroughly mixed, and the mixed raw powder is compression molded by a tablet molding machine, a compression molding machine, a pelletizer or the like. By doing so, the carrier can be produced.

Raw powders of anhydrous potassium compounds such as potassium fluoride and potassium carbonate may be mixed and used as they are, or may be mixed after being pulverized or granulated. Alternatively, it may be pulverized after mixing.

The shape of the compression-molded granular carrier is not particularly limited, but is usually cylindrical, pelletized, spherical, etc., and the particle size is usually 0.5 mm or more, preferably 1-10.
The range is mm. The strength of the carrier is not particularly limited, but may be in the range of 1.5 to 20 kg (radial crushing strength).

The supporting of the alkali metal on the carrier is carried out after firing the carrier. The firing conditions may be any conditions and methods as long as they burn out the organic binder almost completely. It may be fired in air or may be fired in a mixed stream of nitrogen / air. The firing time and the temperature rising speed may be arbitrary. It is also acceptable to dry under reduced pressure at a low temperature before firing. A particularly preferable range of the firing temperature is 350 to
It is 550 ° C. At 350 ° C or lower, the organic binder is liable to be incompletely burned, and at 550 ° C or higher, the anhydrous potassium compound is easily sintered.

The method for supporting the alkali metal on the carrier is, for example, by stirring and mixing the calcined carrier at a temperature above the melting point of the alkali metal, preferably at a temperature of 200 to 450 ° C. under an inert gas atmosphere. You can When sodium metal is used as the alkali metal component before loading, the sodium metal causes an exchange reaction during the loading operation to produce potassium metal. The catalyst of the present invention is
Even with the above-mentioned alkali metal-supporting treatment, no significant decrease in crush strength was observed, and it can be effectively used as a practical catalyst.

Lower α-used in the dimerization method of the present invention
Specific examples of the olefin include ethylene, propylene,
1-butene, isobutylene, 1-pentene, 1-hexene and the like can be mentioned. Among the dimerizations or codimerizations using these lower α-olefins, the production of 4-methylpentene-1 by the dimerization of propylene, the production of 1-pentene by the codimerization of propylene and ethylene, 1- It can be used for production of 3-methylpentene-1 by co-dimerization of butene and ethylene, production of 2-methylpentene-1 by co-dimerization of isobutylene and ethylene, and the like. In particular, it can be preferably used for the production of 4-methylpentene-1 by dimerization of propylene.

The dimerization or codimerization reaction using the catalyst of the present invention can be carried out by a gas phase method or a liquid phase method under heating, and a gas phase fixed bed system is particularly preferable. When carrying out the reaction by the gas phase method, the reaction temperature is usually 50 to 250.
C., preferably in the range of 80 to 200.degree. The reaction pressure is
It is in the range of 20 to 200 kg / cm ² G. The liquid hourly space velocity (LHSV) of α-olefin is usually 0.5 to 10 h ^-1 , preferably 1
The range is from ~ 7h ^-1 .

[0026]

INDUSTRIAL APPLICABILITY The catalyst of the present invention can improve the selectivity to a desired product while maintaining the activity in the dimerization or codimerization reaction of a lower α-olefin, and the catalyst in use can be used. The characteristic is that the decrease in the physical strength is small.

[0027]

EXAMPLES Examples of the present invention will be described below.

Example 1 50 parts by weight of potassium fluoride powder having an average particle size of 270 μm and a loose packing bulk density of 1.148 g / ml and 50 parts by weight of potassium carbonate powder having an average particle size of 250 μm and a loose packing bulk density of 0.953 g / ml. After mixing
The milling process was performed using a Willey crusher (500 μm screen). 0.92wt% graphite powder and 6.
9 wt% crystalline cellulose powder (Asahi Kasei product name: Avicel) was added and mixed well, and then tablet-molded into a cylindrical carrier having a diameter of 3 mm and a height of 3 mm. The crush strength (radial direction) measured using a Kiya hardness meter was 1.9 kg. 20 at 100 ° C
hr After drying under reduced pressure, the weight loss was 3.3% and the crush strength was 1.4 kg. This dry carrier is placed under a nitrogen / air mixed atmosphere at 370 ° C.
For 2 hours and then in air at 500 ° C for 2 hours. Weight loss
The crush strength was 7.7% (based on the weight of the molded carrier) and 2.6 kg. 2.50 wt% metallic sodium was added to the calcined support under a nitrogen atmosphere, and the mixture was stirred at 370 ° C. for 4 hours to prepare a catalyst. The crush strength of the catalyst was 3.3 kg. 54.91 g of this catalyst
Was filled in a tubular reactor having a catalyst portion volume of 54 ml and an inner diameter of 21 mm,
While maintaining the reaction pressure at 100 kg / cm ² G and the reaction temperature at 150 ° C, propylene was supplied at a liquid hourly space velocity (LHSV) of 4.8 h ^{-1 to} carry out a continuous flow reaction. The conversion of propylene was 13.1% and the selectivity of 4-methylpentene-1 was 92.8%. The crush strength of the catalyst after the reaction is 2.2 kg (the strength retention rate is 67% compared to before the reaction).
)Met. The treatment conditions, physical properties, and reaction results of the carrier and the catalyst are summarized in Table 1, Table 2, Table 3, and Table 4.

Example 2 The procedure of Example 1 was repeated, except that the drying time was changed to 23 hours and the final firing conditions were changed to 400 ° C. and 7 hours. Catalyst part volume 54
The catalyst weight that could be loaded in ml was 56.06 g. The treatment conditions, physical properties, and reaction results of the carrier and the catalyst are summarized in Table 1, Table 2, Table 3, and Table 4.

Example 3 Example 3 was repeated except that the crushing strength of the molded carrier was 2.8 kg and the drying time was 18 hours. The treatment conditions, physical properties, and reaction results of the carrier and the catalyst are summarized in Table 1, Table 2, Table 3, and Table 4.

Example 4 The same procedure as in Example 1 was carried out except that 0.92 wt% of graphite and 0.28 wt% of activated carbon were used and the drying time was 18 hours. The treatment conditions, physical properties, and reaction results of the carrier and the catalyst are summarized in Table 1, Table 2, Table 3, and Table 4.

Example 5 Powder of potassium carbonate 1.5 hydrate was pulverized by a Willey pulverizer (2 mm screen). Then at 350 ℃ for 2hr
After drying, the milling process was performed again with a Willey mill (2 mm screen). The average particle size of this powder is 235 μm,
The loosely packed bulk density was 0.829 g / ml. After mixing 50 parts by weight of this powder with 50 parts by weight of the potassium fluoride powder used in Example 1, the mixture was pulverized with a Wiley pulverizer (500 μm screen). 0.92 wt% graphite powder and 6.9 wt% crystalline cellulose powder (Asahi Kasei product name: Avicel) were added to this crushed raw powder and mixed well, and then tablet-molded. 100 ° C
After drying under reduced pressure for 16 hours at 150 ° C in a nitrogen / air mixed atmosphere
The temperature was raised to 320 ° C at a heating rate of 3 ° C / min for 0.5 hr. After that, at 370 ° C for 2 hours, at 500 ° C in air.
It was baked for 2 hours. The catalyst preparation and reaction were performed in the same manner as in Example 1. The treatment conditions, physical properties, and reaction results of the carrier and the catalyst are summarized in Table 1, Table 2, Table 3, and Table 4.

Example 6 Using 16.5 wt% of Avicel and 0.83 wt% of graphite,
The firing conditions were a nitrogen / air mixed atmosphere, and the temperature was raised from 150 ℃ to 320 ℃ at a heating speed of 1 ℃ / min.
The same procedure as in Example 1 was carried out except that the temperature was 2 hours. The treatment conditions and physical properties of the carrier and the catalyst and the reaction results are shown in Tables 1 and 2.
The results are summarized in Tables 3 and 4.

Comparative Example 1 Only potassium carbonate powder having a loose packing density of 0.829 g / ml prepared in Example 5 was used, which was directly mixed with 0.99 wt% of graphite and then tableted. Directly in the air without drying
The same procedure as in Example 1 was performed, except that the baking was performed at 380 ° C. for 2 hours. The catalyst after the reaction had many cracks and chips, and the crush strength could not be measured. The treatment conditions, physical properties, and reaction results of the carrier and the catalyst are summarized in Table 1, Table 2, Table 3, and Table 4.

Comparative Example 2 Potassium fluoride powder having an average particle size of 240 μm and a loose packing density of 1.253 g / ml was crushed with a ball mill and then sieved with 100 μm. The loose packing density of this powder was 1.012 g / ml. This potassium fluoride powder and the potassium carbonate powder used in Example 1 were mixed, then directly mixed with 0.99 wt% graphite without crushing, and then tablet-molded. The drying time was 23 hours, and the baking was performed in the same manner as in Example 1 except that the baking was performed in air at 380 ° C. for 2 hours. The catalyst after the reaction had many cracks and chips, and the crush strength could not be measured. The treatment conditions, physical properties, and reaction results of the carrier and the catalyst are summarized in Table 1, Table 2, Table 3, and Table 4.

Comparative Example 3 The procedure of Example 1 was repeated except that the amount of Avicel used was 2.9 wt%. The crush strength could not be measured because the catalyst after the reaction had not only cracking but also powdering. The treatment conditions, physical properties, and reaction results of the carrier and the catalyst are summarized in Table 1, Table 2, Table 3, and Table 4.

[0037]

[Table 1]

[0038]

[Table 2]

[0039]

[Table 3]

[0040]

[Table 4]

Claims (1)

[Claims] 1. A method for producing an α-olefin dimerization catalyst comprising an alkali metal supported on a compression-molded granular carrier,
As the compression-molded granular carrier, (a) anhydrous potassium compound,
A mixture consisting of carbon and 4 to 20 wt% of a pyrolyzable organic binder, based on the total weight of the carrier, is compression molded, and (b) then,
A method for producing an α-olefin dimerization catalyst, characterized in that the compression molded article is fired to thermally decompose the thermally decomposable organic binder, and the resulting compression molded granular carrier is used.