JP2756493B2 - Method for producing 1-pentene by co-dimerization of ethylene and propylene - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to a method for producing 1-pentene by codimerization of ethylene and propylene in the presence of a catalyst, and more particularly, to a method of codimerizing ethylene and propylene. Accordingly, the present invention relates to a method for industrially advantageously producing 1-pentene with a high yield and a high selectivity per unit weight of a catalyst.

2. Description of the Related Art Various basic catalysts for dimerization and co-dimerization of α-olefin have been conventionally proposed, and an alkali metal is supported on a granular carrier obtained by compression molding of anhydrous potassium carbonate and graphite. The catalyst used was JP-B-59-40503.
It is already known as described in Japanese Patent Publication No. JP-A-59-40506 and Japanese Patent Publication No. Sho 59-40506. In the above publication, a catalyst is prepared using anhydrous potassium carbonate having a bulk density of 0.7 g / ml as anhydrous potassium carbonate constituting a carrier, and the catalyst is prepared by co-dimerization of propylene. , 4-methyl-1-pentene can be prepared.

However, according to such a conventional catalyst, particularly when producing 1-pentene by codimerization of ethylene and propylene, the reactivity of ethylene is much higher than that of propylene. The catalyst activity is likely to be degraded due to the low selectivity of 1-pentene,
The production per weight of catalyst is also low.

In addition, conventional catalysts as described above have a reduced mechanical strength during use and powder in a relatively short period of time.
When used as a fixed bed catalyst, the pressure loss in the reaction tube rapidly increases with time, and the catalyst must be replaced. Also from this point, when a conventionally known catalyst is used, the production amount of 1-pentene per weight of the catalyst is low.

The present invention has been made to solve the above-mentioned problems in the production of 1-pentene by the co-dimerization of ethylene and propylene using a conventional α-olefin dimerization catalyst. Thus, by selecting the reaction conditions in the presence of an improved catalyst having high activity and long life, by co-dimerizing ethylene and propylene, 1-pentene is obtained with high selectivity and high yield. It is an object of the present invention to provide a method for industrially advantageously producing a.

Means for Solving the Problems The present invention provides a method for producing 1-pentene by co-dimerizing ethylene and propylene in a fixed bed system in the presence of a catalyst, wherein (A) the catalyst comprises an alkali metal. A catalyst supported on a compression-molded granular carrier comprising anhydrous potassium carbonate and carbonic acid, wherein (a) said alkali metal is 20 to 90 g atom% of sodium
And (b) the compression-molded granular carrier contains 0.6 to 3% by weight of carbon with respect to anhydrous potassium carbonate, and has a pore volume ratio of 22 to 38% and 1.5 to 1.5%. and having a compressive strength of ~15kg / cm ² G, as a raw powder before anhydrous potassium carbonate compression molding constituting the (c) the carrier has an average particle size 150～600Myuemu, and, of particle size less than 100μm The powder is in the range of 1 to 15% by weight, the powder having a particle size exceeding 600 μm has a particle size distribution in the range of 1 to 20% by weight, and the bulk density is 0.50 g / ml or more; (B) Supply ethylene and propylene in an ethylene / propylene molar ratio of 0.30 to 0.95 and react at a pressure of 30 kg / cm ² or more and a temperature of 80 to 140 ° C. Features.

The catalyst used in the method of the present invention is obtained by supporting an alkali metal on a compression-molded granular carrier composed of anhydrous potassium carbonate and carbon. Such a supported alkali metal contains 20 to 90 g atomic% of sodium and 80 to 10 g atomic% of potassium. Consisting of
Preferably, 30 to 85 g atom% sodium and 70 to 1 potassium
Consists of 5 g atomic%. Such an alkali metal is preferably supported at a rate of 0.5 to 10% by weight, and particularly preferably at a rate of 1 to 5% by weight, based on anhydrous potassium carbonate.

90gat% sodium in the supported alkali metal
More than 10 g at%, the catalyst activity and the desired codimerization product, 1-
The selectivity for pentene is low, especially the induction period leading to the highest activity is significantly longer. On the other hand, when the supported alkali metal contains less than 20 g atomic% of sodium and more than 80 g atomic% of potassium, the resulting catalyst is:
Although the initial activity is high, the catalyst activity decreases significantly with time,
Short catalyst life.

When the supporting ratio of the alkali metal in the anhydrous potassium carbonate is too small, the catalytic activity is low. On the other hand, when it is too large, the alkali metal is easily separated from the anhydrous potassium carbonate, which is not preferable.

When only sodium and potassium are supported on the carrier, a liquid or solid sodium-potassium alloy is usually used. However, in the method of the present invention, the catalyst used may have a component other than the alkali metal supported on a carrier if necessary.In such a case, for example, a paste containing the alkali metal and other components may be used. Is used.

In the catalyst used in the method of the present invention, the support is a granular support obtained by compression-molding a mixture of anhydrous potassium carbonate and carbon. The content of carbon in such a carrier is from 0.6 to 0.6 with respect to anhydrous potassium carbonate.
It is in the range of 3% by weight. When the content of carbon in the carrier is less than 0.6% by weight based on anhydrous potassium carbonate, the catalytic activity, selectivity to a desired dimerization product, the catalyst life, and the like are low. However, even if the carbon content of the carrier exceeds 3% by weight, no improvement in catalytic activity or selectivity to the desired 1-pentene is observed, and furthermore, the anhydrous potassium carbonate and the anhydrous potassium carbonate are not formed by compression molding. It becomes difficult to form a mixture with carbon into a granular support having a compressive strength of 1.5 kg / cm ² G or more, and consequently the catalyst life is short, and a practical catalyst cannot be obtained. In particular, in the method of the present invention, in order to obtain a catalyst having a long catalyst life and a high selectivity to 1-pentene, the content of carbon in the carrier is preferably in the range of 0.8 to 2% by weight. Preferably, there is.

Examples of the carbon include graphite and amorphous carbon, but graphite is particularly preferably used.

In the method of the present invention, for the catalyst to be used, anhydrous potassium carbonate constituting the carrier has an average particle size of 150 to 600 μm as a raw powder before compression molding, and has a particle size of 100.
powder having a particle size of 600 μm or less
powder having a particle size distribution in the range of 1 to 20% by weight and a bulk density of 0.50 g / ml or more,
It is necessary to be in the range of less than ml, especially the average particle size of 20
Powder having a particle size of 0 to 500 μm and a particle size of less than 100 μm is 2
It is preferable that the powder having a particle size exceeding 600 μm has a particle size distribution in a range of 2 to 15% by weight and a bulk density in a range of 0.53 to 0.69 g / ml. .

In particular, in the method of the present invention, the bulk density is 0.55 to 0.68
Using an anhydrous potassium carbonate raw powder in the range of g / ml, a compression-molded granular carrier is prepared together with graphite, and a catalyst comprising an alkali metal supported on the carrier is used. 1-pentene can be produced with a high production rate of 1-pentene and a high conversion and high selectivity.

Raw powder of anhydrous potassium carbonate having a narrow particle size distribution, for example, a normal commercial product has an average particle size in the range of 350 to 800 μm, and powder having a particle size of less than 100 μm and powder having a particle size of more than 600 μm are both 1 weight. %, And even if the anhydrous potassium carbonate is compression-molded together with carbonic acid, a granular support having sufficient strength cannot be obtained. It is inferior in both the life and the selectivity to the target 1-pentene.

Further, in the method of the present invention, when preparing the catalyst to be used, the bulk density of the raw powder is 0.50 g / ml or more, and 0.70 g / ml
By using anhydrous potassium carbonate in the range of less than 0.5 ml, preferably 0.53 to 0.69 g / ml, most preferably in the range of 0.55 to 0.68 g / ml, the mechanical strength is significantly improved and thus the catalyst life is increased. Significantly longer catalysts can be obtained.
That is, by preparing a compression-molded granular carrier using the anhydrous potassium carbonate raw powder having a high porosity as described above,
It is possible to obtain a catalyst having high catalytic activity and having a long service life of more than one year, particularly in a continuous reaction using a fixed bed system.

However, when the bulk density of the anhydrous potassium carbonate raw powder is smaller than 0.50 g / ml, the powder is crushed when mixed with carbon before compression molding, and the raw powder does not have the above-mentioned particle size distribution. Due to the molding, a granular carrier having a strength in the above-described range cannot be obtained, and the resulting catalyst is, instead,
The life is shortened.

In the catalyst used in the method of the present invention, the support is a granular support obtained by compression-molding anhydrous potassium carbonate and carbon as described above, and has a pore volume ratio in the range of 22 to 38%. In addition, it is necessary that the compressive strength is in the range of 1.5 to 15 kg / cm ² . When the pore volume ratio and the compressive strength of the support are out of the above ranges and the pore volume ratio is large and the compressive strength is small, the obtained catalyst has a relatively high initial activity, but the catalytic activity decreases with time. In addition, since the strength of the catalyst is insufficient, the catalyst is easily disintegrated with time during use, powdered, and the catalyst life is short. On the other hand, when the pore volume ratio is small and the compressive strength is large, the resulting catalyst has low activity and low selectivity to the desired 1-pentene.

However, in the granular support obtained by compression-molding anhydrous potassium carbonate and carbon according to the method of the present invention, the pore volume ratio is in the range of 22 to 38%, preferably 26 to 33%, and the compressive strength 1.5~15kg / cm ² G, preferably, Yotsute to be in the range of 2 to 10 kg / cm ² G, catalytic activity, the catalyst life and industrial excellent in selectivity to dimerization products, A useful catalyst can be obtained, and 1-pentene can be industrially advantageously produced.

The catalyst used in the method of the present invention can be prepared by various methods. First, the carrier is usually prepared by the following method. Carbon and raw powder of anhydrous potassium carbonate having the above-described properties are sufficiently mixed, and the mixture is mixed with a tableting machine, a compression molding machine, a pelletizer, or the like to have the above-described pore volume ratio and compressive strength. As described above, compression molding is performed on a granular carrier. The shape of the compression-molded granular carrier thus obtained is not particularly limited, but is usually cylindrical, tablet-like, pellet-like, spherical, or the like, and the particle size is usually 0.5 mm or more, Preferably, 1 to 10 m
m, particularly preferably in the range of 3 to 5 mm.

Various methods can be used to support the alkali metal on such a carrier. Sodium, when brought into contact with anhydrous potassium carbonate under heating, undergoes an alkali metal exchange reaction with potassium, resulting in potassium and anhydrous sodium carbonate in the carrier. Therefore, in the preparation of the catalyst according to the present invention, necessary amounts of sodium and potassium can be supported on the carrier using only sodium in consideration of the alkali metal exchange reaction. Of course,
Sodium and potassium, for example, a sodium-potassium alloy as described above, may be used to support them on a carrier.

To support the alkali metal on the carrier, specifically,
For example, the following method may be used. That is, a mixture of sodium and other supporting components as necessary, or a mixture of a sodium-potassium alloy and other supporting components as necessary, together with the compression-formed granular carrier, is heated in an inert gas atmosphere. By stirring below, sodium and potassium, and if necessary, other supporting components can be supported on the carrier.

As described above, when the alkali metal is supported on the carrier, the heating temperature is usually a temperature in the range of 150 to 450 ° C., but the catalytic activity, the catalyst life, and the selectivity to the dimerization product are reduced. In order to obtain an excellent catalyst, the temperature is particularly preferably in the range of 200 to 400 ° C.

According to the method of the present invention, in the method of producing 1-pentene by co-dimerizing ethylene and propylene in a fixed bed system in the presence of the catalyst thus obtained, ethylene and propylene are Ethylene / propylene is supplied in a molar ratio of 0.30 to 0.90, pressure is 30 kg / cm ² or more,
The reaction is performed at a temperature of 80 to 130 ° C.

The reaction is usually performed by a continuous fixed bed flow method using a high-pressure tubular reactor having a tube diameter of 25 to 80 mm, but a solvent or an accompanying gas may be used together with ethylene and propylene.

In the method of the present invention, ethylene and propylene are
The ethylene / propylene is passed through the fixed bed catalyst in a molar ratio of 0.30 to 0.95. When the ethylene / propylene molar ratio is smaller than 0.30, 4-methyl-1-pentene is largely produced as a by-product of dimerization of propylene, and 1-pentene, which is a target co-dimerization product, is produced with high selectivity. I can't get it. On the other hand, if the ethylene / propylene molar ratio is 0.
When it is larger than 95, a large amount of 3-ethyl-1-pentene is by-produced, and similarly, 1-pentene cannot be obtained with high selectivity.

The reaction temperature ranges from 80 to 140 ° C, preferably from 90 to 120 ° C. When the reaction temperature is lower than 80 ° C., the reactivity of α-olefin is low, and the generation of undesirable by-products is high. However, when the reaction temperature exceeds 140 ° C,
When the amount of by-produced 2-pentene increases, not only cannot 1-pentene be obtained with high selectivity, but also a polymer adheres to the surface of the catalyst, leading to deterioration in catalytic activity.

The reaction pressure is 30 to 200 kg / cm ² G, preferably 40 to 150 k
g / cm ² G. When the reaction pressure is lower than 30 kg / cm ² G, the reaction rate is low, which is disadvantageous for industrial production of 1-pentene. The upper limit of the reaction pressure is not particularly limited, but usually, from a practical viewpoint, 200 k
g / cm ² G. Further, the liquid hourly space velocity (LHSV) of the mixture of ethylene and propylene is usually in the range of 0.1 to 15 hr ^-1 , preferably 0.5 to 10 hr ^-1 .

Ethylene and propylene are contacted with the catalyst under such conditions for 5 to 500 seconds.

Examples of the solvent or the accompanying gas include saturated hydrocarbons such as methane, ethane, propane, hexane, cyclohexane, octane, and decane.When the solvent or the accompanying gas is used, ethylene and propylene are used. Is preferably 30% by weight or more.

After the completion of the reaction, 1
-Separating pentene and unreacted ethylene and propylene, the unreacted material being recycled to the reaction;

Effect of the Invention As described above, in the method of the present invention, for the catalyst to be used, when preparing a compression-molded granular support composed of anhydrous potassium carbonate and carbon, in particular, while using anhydrous potassium carbonate having a predetermined bulk density, 1-pentene can be industrially produced at a high production rate and a high selectivity per unit weight of the catalyst by the co-dimerization of ethylene and propylene by appropriately selecting the reaction conditions. Can be advantageously manufactured.

EXAMPLES Hereinafter, the present invention will be described with reference to examples, but the present invention is not limited to these examples.

In addition, below, the measuring method of the physical property of a support | carrier and a catalyst is as follows.

Particle size distribution of anhydrous potassium carbonate raw powder Combine JIS standard sieves from 16 meshes to 20 meshes, put about 150 g of anhydrous potassium carbonate raw powder sample on top, put the whole in a polyethylene bag and seal did. Attach this sieve to a loader type vibrating shaker,
10 at the conditions of shaking 290 times / min and hammer 156 times / min.
Sieved for minutes.

The weight of anhydrous potassium carbonate on each sieve after sieving in this manner was measured, the weight percentage was calculated, and the average particle size was determined from the RRT diagram.

Pore volume ratio of the carrier The specific gravity of about 10 g of the carrier sample previously dried by heating at 300 ° C for 2 hours is measured in mercury and carbon tetrachloride at 40 ° C, and the ratio of the pore volume to the carrier volume Was determined as a volume percentage by the following equation.

Here, DHg and DCCl ₄ are the specific gravities of the carrier measured in mercury and carbon tetrachloride, respectively, and ρHg and ρCCl ₄ are the densities of mercury and carbon tetrachloride at 40 ° C., respectively.

Graphite content in carrier 50 g carrier sample previously dried by heating at 300 ° C for 2 hours
After adding 0 ml and 20 ml of methanol and stirring with a magnetic stirrer for 20 minutes, the mixture was further stirred with an ultrasonic cleaner for 30 minutes.

After washing the released graphite with water, it is washed at 100 ° C for 2 hours.
After drying for a time, the weight was measured, and the weight percentage based on anhydrous potassium carbonate in the carrier was determined.

Carrying alkali metal component 15 ml of water was added to approximately 2 g of the weighed contact in a nitrogen atmosphere,
The amount of generated hydrogen gas was measured with a gas jar.
Temperature at the time of measurement is t (° C), pressure is P (mmHg), temperature t
At (° C.), the partial pressure of water was PH ₂ O (mmHg), the amount of generated gas was V (ml), the amount of supported alkali metal in catalyst sample M (g) was A (g), and the graphite content was The values of A and B were determined from the following equations, where C (g) and the amount of alkali metal carried on 100 g of anhydrous potassium carbonate was B (g 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 the mixture was allowed to stand at room temperature for 1 hour. Then, the carrier and other solids were separated by centrifugation. The amount of sodium alkoxide and the amount of potassium alkoxide eluted in the isopropyl alcohol thus obtained were measured by the atomic absorption method, and the Na / K ratio was determined from both values.

The amounts of sodium and potassium supported on the catalyst with respect to 100 g of anhydrous potassium carbonate are calculated based on the amount of alkali metal supported on 100 g of anhydrous potassium carbonate B (g atoms) determined above.
And the Na / K ratio were determined by the following equation.

Bulk density of anhydrous potassium carbonate raw powder A funnel with a drop at the lower end and an inner diameter of 26.5 mm, an inner diameter of the upper end of 9.4 mm, a height of 100 mm, and an inner volume of 150 ml is dropped at the lower end of the funnel. It was fixed vertically so that the height to the mouth was 100 mm. A cylindrical receiver having an inner diameter of 39 mm, a height of 81 mm and an internal volume of 98.0 ml was placed directly below the sample dropping port of the funnel.

The powder of the anhydrous potassium carbonate sample was placed in the funnel, the sample dropper at the lower end was opened, and the sample powder was dropped into the receiver. The sample on the top of the receiver was scraped horizontally, the weight of the sample powder in the receiver was measured, and the bulk density was determined.

 Other properties were measured by conventional methods.

Example 1 (Preparation of catalyst) The average particle diameter was 280 μm, and the particle diameter was less than 100 μm.
Weight%, particle size exceeds 600μm, up to 1000μm is 3.4% by weight
With a bulk density of 0.68 g / ml and a pore volume of 0.
1.1 wt% of graphite was added to 45 ml / g of anhydrous potassium carbonate, mixed well, and then tableted into a cylindrical carrier having a diameter of 3 mm and a height of 3 mm. The pore volume ratio of this carrier was 27%, and the compressive strength was 6.8 kg / cm ² G.

After drying 97.2 g of this carrier at 350 ° C. in a nitrogen stream, 2.8 g of metallic sodium was added under a nitrogen atmosphere, and 240 ° C.
For 5 hours to prepare a catalyst.

In the obtained catalyst, the supported alkali metal was 48 g atom% of sodium and 52 g atom% of potassium, and the amount supported on anhydrous potassium carbonate was 2.7% by weight.

The catalyst 16 thus prepared was charged into a tubular high-pressure gas-phase reactor having an inner diameter of 50 mm, and the pressure of the reactor was set to 100 kg / cm ² G,
While maintaining the temperature at 105 ° C, the ethylene / propylene molar ratio
Liquid space velocity (LHSV) of ethylene and propylene at 0.55
Feeding was carried out at 2.5 hr ^{-1 to} carry out a continuous reaction.

As a result of the reaction, the conversion of ethylene was 83 mol%, and the composition of the product was 93.2 mol% of 1-pentene,
Penten 1.4 mol%, 4-methyl-1-pentene 3.0
Mol%, 3-ethyl-1-pentene was 1.9 mol%, and other 0.5 mol%.

In addition, the conversion of ethylene shows little change with time, and
The total daily production was 98 g / g catalyst.

Examples 2 and 3 The ethylene / propylene molar ratio supplied to the reactor was 1st.
Co-dimerization of ethylene and propylene was carried out in the same manner as in Example 1 except that 0.8 and 0.3 were used as shown in the table. Table 1 shows the reaction results.

Comparative Example 1 The ethylene / propylene molar ratio supplied to the reactor was 1.1
Co-dimerization of ethylene and propylene was performed in the same manner as in Example 1 except that Table 1 shows the reaction results.

In this reaction, the discharge of the reaction solution from the reactor decreased extremely 10 hours after the start of the reaction. Then, when the reactor was opened and examined, adhesion of the polymer substance to the surface of the catalyst was observed.

Comparative Example 2 The ethylene / propylene molar ratio supplied to the reactor was 0.2
Co-dimerization of ethylene and propylene was performed in the same manner as in Example 1 except that Table 1 shows the reaction results.

Compared with Example 1, 4-methyl-1-pentene was more by-produced, and the target 1-pentene was selected. The selectivity has decreased significantly.

Comparative Example 3 Co-dimerization of ethylene and propylene was performed in the same manner as in Example 1 except that the reaction temperature was changed to 150 ° C. Table 1 shows the reaction results.

Compared with Example 1, 4-methyl-1-pentene has much more by-products and 2-pentene also has many by-products. As a result, the selectivity of the target 1-pentene is extremely low.

Comparative Example 4 Co-dimerization of ethylene and propylene was performed in the same manner as in Example 1 except that the reaction temperature was 70 ° C. Table 1 shows the reaction results.

Compared with Example 1, the conversion of ethylene is extremely low.

Claims (2)

(57) [Claims] 1. A method for producing 1-pentene by co-dimerizing ethylene and propylene in a fixed bed system in the presence of a catalyst, wherein (A) the catalyst comprises converting an alkali metal to anhydrous potassium carbonate and carbon. A catalyst supported on a compression-molded granular carrier comprising: (a) 20 to 90 g atom% of the alkali metal sodium;
And (b) the compression-molded granular carrier contains 0.6 to 3% by weight of carbon with respect to anhydrous potassium carbonate, and has a pore volume ratio of 22 to 38% and 1.5 to 1.5%. and having a compressive strength of ~15kg / cm ² G, as a raw powder before anhydrous potassium carbonate compression molding constituting the (c) the carrier has an average particle size 150～600Myuemu, and, of particle size less than 100μm The powder is in the range of 1 to 15% by weight, the powder having a particle size exceeding 600 μm has a particle size distribution in the range of 1 to 20% by weight, and the bulk density is 0.50 g / ml or more; (B) Supply ethylene and propylene in an ethylene / propylene molar ratio of 0.30 to 0.95 and react at a pressure of 30 kg / cm ² or more and a temperature of 80 to 140 ° C. A method for producing 1-pentene by co-dimerization of ethylene and propylene. 2. The 1-pentene according to claim 1, wherein the anhydrous potassium carbonate constituting the carrier has a bulk density in the range of 0.53 to 0.69 g / ml as a raw powder before compression molding. Production method.