JPH0254806B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a novel process for producing 4-methyl-1-pentene by dimerizing propylene.

By polymerizing 4-methyl-1-pentene, a polymer with high transparency and excellent heat resistance, mechanical and electrical properties, and chemical resistance can be obtained. It is a compound that shows particularly excellent performance as a comonomer for improving various physical properties of polyolefin products, such as transparency and environmental stress cracking resistance, when producing polyolefins by polymerizing them.

Traditionally, propylene has been dimerized in the presence of alkali metals such as sodium and potassium.
-Methyl-1-pentene is known to be obtained (e.g. J.Org.Chem., 30, 3286 (1965)).
(reported by AWShow et al.).

Furthermore, propylene was dimerized using a catalyst with an alkali metal supported on a carrier, and 4-methyl-1
- It is also known that it is possible to obtain pentene. As the carrier in this case, graphite, potassium carbonate, alkali metal silicate, alkali metal halide, magnesium sulfate, talc, etc. are used.

However, these and other known methods have relatively low yields of propylene dimer and selectivity for 4-methyl-1-pentene, and in addition to the desired 4-methyl-1-pentene, cis and
trans 4-methyl-2-pentene, 2-methyl-1-pentene, 2-methyl-2-pentene, 1
-hexene, cis and trans 2-hexene, and cis and trans 3-hexene were produced in large quantities as by-products. Furthermore, these isomers have close boiling points to each other, and in order to obtain the desired 4-methyl-1-pentene with sufficient purity, a precise distillation operation is required, resulting in a large cost for purification. It also had.

In addition, many of the catalysts used in these known methods have a long induction period, which requires a long time to reach their maximum activity, and it takes a long time for the reaction to stabilize, resulting in poor economic efficiency and stable operation. But there were many things that were inferior. In addition, many of these known dimerization catalysts have not only dimerization ability but also polymerization ability, and the polymerization reaction proceeds along with the dimerization reaction, and the generated polymer covers the catalyst surface and gradually becomes active. There were times when I lost my life. In particular, when such a catalyst is used, it has often been observed that the selectivity tends to decrease as the activity decreases. The catalyst that has lost its activity in this way has been solidified by the resinous polymer inside the reactor, but there is still a sufficiently highly active catalyst remaining inside the reactor, and catalyst replacement is possible. Therefore, when extracting this waste catalyst, there is a risk of ignition due to contact with atmospheric oxygen, moisture, etc.
Another disadvantage was that it was inconvenient to handle due to the danger of fire.

The present inventors conducted intensive research to improve the drawbacks of conventionally known methods and catalysts as described above, and as a result, discovered a method using a new catalyst system as disclosed in JP-A-57-126426. Ta. This method uses a compound represented by K ₂ O・xAl ₂ O ₃ (1) as a support for the reaction catalyst (in the above formula, x is
0.5≦x≦11, preferably 1≦x≦5) on which sodium and/or sodium amide is supported, and furthermore, this which has been subjected to hydrogen treatment in advance is used as a catalyst. It dimerizes propylene. According to this method, it is not only possible to improve the drawbacks of conventional methods using various catalysts, but also it is possible to increase the amount of sodium supported on the carrier, and the reaction rate and 4-methyl -The selectivity of 1-pentene can be significantly increased, and
It has been found that this activity and selectivity can be kept at high values for a very long time.

However, as a result of further intensive studies on the above method, the present inventors found that 4-by-4 dimerization of propylene was achieved by an entirely unexpected method.
The present inventors have discovered that the method for producing -methyl-1-pentene can be improved and have completed the present invention.

Alkali metals or organic alkali metal compounds usually decompose on contact with water, oxygen, etc. and their catalytic activity is lost, so contact with these is avoided. However, the present inventors found that the compound represented by formula (1) above was used as a carrier for the reaction catalyst, and in some cases, an excessive amount of potassium carbonate, which was used as a raw material for producing the carrier, was mixed in the compound without reacting. These include sodium, potassium,
When carrying out a dimerization reaction using as a catalyst a catalyst that supports at least one element or compound selected from the group of sodium amide and potassium amide, the raw material Quite surprisingly, the presence of a moderate amount of oxygen in propylene, far from deactivating its catalytic activity, increased its dimerization activity and selectivity for 4-methyl-1-pentene, or Although the activity was slightly decreased, it was found that the selectivity for 4-methyl-1-pentene was significantly improved.

That is, in the method for producing 4-methyl-1-pentene of the present invention, propylene is converted into a compound represented by the following formula (1) K ₂ O.xAl ₂ O ₃ (1) (however, in the above formula, x is
At least one element or compound selected from the group consisting of sodium, potassium, sodium amide, and potassium amide is supported on a carrier whose main component is 0.5≦x≦11. 4-methyl-
The method for producing 1-pentene is characterized in that propylene containing 2 to 500 ppm of oxygen by weight is used as a reaction raw material.

The compound represented by the above formula (1) used as the main component of the carrier in the method of the present invention can be obtained, for example, by the following method. That is,
KOH, KOR ¹ (R ¹ is at least one selected from C ₁ to C ₂₀ linear or branched aliphatic hydrocarbon residues, C ₆ to _{C 30} aryl groups, and aralkyl groups), KHCO ₃ , K ₂ CO ₃ (including those containing crystal water), KH, KR ² (R ² is a C ₁ to C ₂₀ linear or branched aliphatic hydrocarbon residue, a C ₆ to C ₃₀ aryl and at least one potassium-containing compound such as aralkyl group or aralkyl group), and alumina hydrate such as hydrogillite, vialite, boehmite, diaspor, α- and γ-alumina. ,Al
(OR ³ ) ₃ (R ³ is a mixture of at least one selected from C ₁ to C ₂₀ linear or branched aliphatic hydrocarbon residues, C ₆ to C ₃₀ aryl groups, or aralkyl groups) and at least one kind of aluminum-containing compound such as
Preferably, it is obtained by reacting at a temperature of 500 to 1500° C. in the presence or absence of air, nitrogen, etc. for 1 to 20 hours. In the compound represented by formula (1), x preferably takes a value in the range of 1≦x≦5.

The compound constituting this carrier is composed of K ₂ O and Al ₂ O ₃ , but this is a convenient representation of the composition of the carrier produced when the charging composition of the raw reagent changes. However, the compounds of these constituent elements do not exist as they are, but mainly as a double oxide. Therefore, simply mixing K ₂ O and Al ₂ O ₃ is a completely different type of carrier, and it is unlikely that the improvement in activity and selectivity expected when using the above carrier will be achieved. Can not.

When potassium carbonate is used as a potassium-containing compound that is a raw material for the catalyst support used in the method of the present invention, even if potassium carbonate is used so that x < 0.5, A carrier having the same improvement effect as when x in the compound is 0.5≦x≦11 can be obtained. That is, when potassium carbonate is used, an excess amount of potassium carbonate remains unreacted in the carrier, but the compound represented by formula (1) above and potassium carbonate can be handled in exactly the same way. It is something. In other words, as the carrier for the catalyst used in the method of the present invention, the compound represented by the above formula (1) may be used alone, or the support may be manufactured using the compound represented by the above formula (1) as a main component. A small amount of unreacted potassium carbonate used as a raw material may also be present. In this case, the remaining amount of potassium carbonate is calculated using the above formula.
It is preferably 30% by weight or less of the compound represented by (1).

In conventional catalysts for producing 4-methyl-1-pentene, the amount of sodium or potassium supported on the carrier is less than 5wt% because the carrier itself is inert or has a small porosity. , usually about 1 to 3 wt%. If these carriers
If you try to support more than 5wt% of sodium or potassium, these alkali metals will adhere to the surface of the carrier in a muddy form, causing the catalyst to coagulate into lumps, making it difficult to handle industrially. Not only was this difficult, but the dimerization activity was often extremely reduced. Furthermore, in order to adopt a fixed bed continuous flow method as a dimerization reaction method, it is necessary to make the catalyst into a pellet shape, but conventionally, the catalyst carrier for producing 4-methyl-1-pentene was Potassium carbonate, which is used as a raw material, does not have caking properties, so it was not possible to pelletize it. Therefore, in many of the known catalysts, pellets are manufactured using graphite or the like as a binder, and sodium or potassium is supported on the pellets. However, such pellets also have the disadvantage of short catalyst life because they have low mechanical strength and tend to disintegrate during use. On the other hand, the compound represented by formula (1), which is the carrier used in the method of the present invention, can absorb and support large amounts of sodium, potassium, their hydrides, amides, etc. very quickly. It maintains a very good dispersion state, and can be used as is or by reacting with oxygen according to the method of the present invention described later, to achieve higher activity and selectivity in the propylene dimerization reaction. The catalyst provided can be formed in the following manner.

As mentioned above, this catalyst system has the following characteristics: the catalyst has good dispersibility and does not aggregate, has high activity and selectivity, and has an extremely short induction period at the start of the reaction. It is very suitable for a complete mixing mode reaction in which it is introduced continuously with propylene into a tank reactor.

In addition, unlike potassium carbonate, the compound represented by formula (1), which is the main component of the carrier used in the method of the present invention, is formed by molding a kneaded product of the above-mentioned raw materials by a known method such as extrusion molding or compression molding. By then firing it, it is possible to make pellets with very high strength. The carrier thus obtained in the form of pellets can absorb and support large amounts of sodium, potassium, their hydrides, amides, etc. very quickly, similar to the carrier in the form of powder. Therefore, according to the method of the present invention,
High activity and selectivity are achieved in the propylene dimerization reaction. Furthermore, the catalyst used in the method of the present invention has large pellet strength, high activity, and high selectivity, and is therefore optimal for the production of 4-methyl-1-pentene by a fixed bed continuous flow system.

The shape of the carrier used in the method of the present invention can be selected from any shape, such as a fine powder, a sphere of about 10 mm, or a columnar shape, depending on the reaction mode, the shape and capacity of the reactor, and the like. These can be produced by crushing and classifying the lumps of the compound represented by formula (1) obtained after firing the carrier raw material, or by kneading the raw materials and pelletizing them by extrusion molding, compression molding, etc., and then firing them. , can be manufactured in any desired shape and size.

The method for supporting sodium and/or potassium on the above carrier can be carried out in exactly the same manner whether the carrier is a powder or a pellet. Alternatively, a method of stirring and mixing with potassium, a method of depositing vapor of sodium and/or potassium on a carrier, etc. can be adopted. In addition, as a method for supporting sodium amide or potassium amide, the carrier is immersed in an ammonia solution of sodium amide or potassium amide by dissolving sodium or potassium in liquefied ammonia.
A common method is to fully impregnate the material and then evaporate the ammonia to support the material.

The amount of catalytically active species sodium, potassium, sodium amide, and potassium amide (hereinafter collectively referred to as alkali metals) supported on the carrier is 0.1 to 20 wt% in terms of sodium atoms and/or potassium atoms. preferable. The amount supported
Even at an extremely high value of 20wt%, almost no tar or resinous substances are observed, and since the supported amount can be increased, it is effective against moisture and other impurities that enter the reaction system. It exhibits strong resistance even when exposed to heat, and can maintain high activity and selectivity for a very long period of time. Of course 0.1~1wt%
Even at such a low loading amount, the activity is only slightly reduced and there is no particular problem in carrying out the method of the present invention. Generally, it is preferable to use one supported in an amount of about 1 to 15 wt%.

The product obtained in this way includes the catalyst used in the method of JP-A-57-126426 mentioned above, and it already has catalytic activity for the dimerization reaction of propylene. .

However, in the method of the present invention, when carrying out the propylene dimerization reaction using such a catalyst, 2 to 25% by weight of propylene is added to the reaction raw material propylene.
ppm, more preferably 10 to 200 ppm by weight of oxygen is used. Conventionally, propylene used as a raw material was one that contained almost no oxygen. In addition, when some amount of oxygen is present, a product from which oxygen has been removed beforehand is used. In order to contain oxygen at the above concentration in propylene, a desired concentration composition can be obtained by dissolving oxygen in propylene under pressure. The oxygen concentration in propylene, the reaction raw material, is 2% by weight.
If it is less than ppm, it will take a considerable time to achieve the effect of oxygen inclusion in the raw material propylene according to the present invention, which is not practical. On the other hand, when the oxygen concentration in propylene exceeds 500 ppm by weight, propylene and oxygen react to form a resinous substance, which causes coking in the reactor, which is not suitable.

The raw material propylene used in the reaction does not necessarily have to be of high purity, but it should be one from which other olefins, diolefins, water, air, carbon dioxide, etc. have been removed to the extent that is normally industrially possible. It is preferable to use Although it is better not to include saturated hydrocarbons such as ethane, propane, and butane, there is no problem if they are included.

When carrying out the method of the present invention, it is not necessarily an appropriate method to constantly use propylene having the above oxygen concentration from the time when a newly prepared catalyst is started to be used until the end of the catalyst life. . Oxygen mixed in the raw material propylene reacts almost quantitatively with the alkali metals supported on the catalyst carrier, and the cumulative amount of oxygen to the catalyst is 0.1 to 20 mol%, preferably 0.3% to the alkali metals. It is preferable to control it within the range of ~10 mol%,
Within this cumulative oxygen amount range, the present invention exhibits high activity and selectivity improvement effects in the propylene dimerization reaction. If the cumulative amount of oxygen is less than 0.1 mol %, the effect of oxygen inclusion in the raw material propylene according to the present invention cannot be sufficiently exhibited. On the other hand, if the amount of oxygen to be catalytically treated exceeds 20 mol %, the selectivity in the propylene dimerization reaction remains high, but the activity decreases and becomes uneconomical. Therefore, when the cumulative amount of oxygen to the catalyst reaches the above range, the raw material propylene should be changed to one with extremely low oxygen content or one that does not contain oxygen at all to carry out the dimerization reaction. It is preferable to continue.

According to the method of the present invention using a catalyst in which the cumulative amount of oxygen to the catalyst reaches a predetermined range by using propylene containing oxygen as a reaction raw material as described above, the activity of propylene dimerization and The selectivity for 4-methyl-1-pentene is significantly improved. The reason for this is not clear so far, but perhaps the reaction of the alkali metals with oxygen changes the electronic state around the active sites of the alkali metals on the carrier, and the coordination of propylene is regulated. This is probably because dimerization becomes more likely to occur and isomerization becomes less likely to occur.

Another important feature of the process of the present invention is that when the reaction is started by introducing propylene after filling the reactor with fresh catalyst, the induction period until the reaction starts is extremely short. In the catalyst systems known so far, even when the induction period is short,
It was known that it could last up to 15 hours, or even several days in some cases.

In carrying out the propylene dimerization reaction by the method of the present invention, various catalytic reaction modes are possible, including batch type using an autoclave,
A semi-batch type or a complete mixing tank type continuous reaction method in which the catalyst and the raw material propylene are continuously supplied to an autoclave, a fixed bed type continuous reaction method in which the catalyst is packed in a reactor and the raw material propylene is circulated therein, etc. can be adopted.

Further, suitable reaction conditions for the propylene dimerization reaction of the present invention are a temperature range of 100 to 250°C, preferably 140 to 180°C, and a suitable pressure range of 20 to 250°C.
~200Kg/ ^cm2 .

When using an autoclave, there is no particular restriction on the amount of catalyst to be used relative to the raw material propylene, but a range of 0.5 to 20 wt% is practically preferred. In addition,
The amount of catalyst used refers to the total amount of the carrier and supported alkali metals.

In addition, the reaction time (in the case of batch type or semi-batch type) or residence time (in the case of continuous type)
is preferably in the range of 1 to 10 hours. In fixed bed continuous process, liquid hourly space velocity (LHSV) is 0.1 to 10.
A range of (V/V·hr) is preferable.

In any of these reaction modes, it is not possible to carry out the reaction using an aliphatic hydrocarbon such as heptane, octane, dodecane, a mixture thereof, or a compound that does not cause a side reaction in this reaction as a solvent. It is possible.

The present invention will be explained in more detail below using Examples.

Example 1 66g of potassium hydroxide pellets (containing 15% moisture) are crushed into fine powder and boehmite 80g
g was mixed well, placed in an alumina crucible, and fired at 1200°C for 5 hours in an air atmosphere. After cooling, the fired product was taken out, placed in an alumina pot, and ground in a centrifugal ball mill for 2 hours.
A material finer than 60 mesh was used as a carrier.

60g of this carrier was placed in a 3-necked flask containing 300ml.
The mixture was heated to 150° C. under a nitrogen gas atmosphere, and 6 g of sodium was added while stirring. After addition, increase the temperature to 200
℃ and continued stirring for 1 hour to obtain a catalyst that was uniformly supported.

A propylene dimerization reaction was carried out using this catalyst. That is, 15 g of this catalyst was placed in a 1000 ml stainless steel autoclave which had been thoroughly dried and purged with nitrogen, and 150 g of propylene in which 100 ppm of oxygen had been dissolved under pressure was added, and the reaction was carried out at 160° C. for 4 hours. As a result, the cumulative amount of oxygen to the catalyst is
It was 0.8 mol%. After the reaction was completed, the autoclave was quenched with tap water to stop the reaction, and unreacted propylene was collected in a trap in a dry ice-methanol bath. Furthermore, the solvent, reaction products, etc. remaining in the reactor were recovered by vacuum distillation.
After evaporating the propylene previously collected in the trap, the recovered reaction liquid was combined with the remaining portion with a boiling point higher than that of the dimer, and was coated with squalane.
When analyzed by gas chromatography using a long glass capillary column, the reaction rate of propylene was 36%, and 4-methyl-1
-Selectivity for pentene was 92%. Therefore, the activity per gram of this catalyst per hour is 0.828
(g-4-methyl-1-pentene/g-catalyst/hr)
(Description of units will be omitted in the following examples).

Comparative Example 1 A propylene dimerization reaction was carried out under exactly the same conditions as in Example 1, except that propylene containing no oxygen (oxygen content <1 ppm) was used as a reaction raw material. As a result of the analysis, the reaction rate of propylene was
26%, selectivity for 4-methyl-1-pentene is 89%
The activity of this catalyst was 0.579.

Example 2 (See Example 1 for the chemical reaction formula) Dimerization of propylene was carried out in the same manner as in Example 1 using 16 g of a catalyst in which 5 wt% of potassium was supported instead of sodium on the carrier used in Example 1. The reaction was carried out. In this example, the cumulative amount of oxygen to the catalyst is
It was 2.2 mol%. As a result of analysis, the reaction rate of propylene was 31%, the selectivity of 4-methyl-1-pentene was 91%, and the activity was 0.529.

Example 3 100g of anhydrous potassium carbonate and aluminum hydroxide
78.0g, each with a particle size smaller than 16mesh, mixed to be sufficiently uniform, and heated to 1100℃.
The carrier was prepared by firing at a temperature of 5 hours. The K/Al ratio of this support was determined by atomic absorption spectrometry.
Al=1.45. Calculating from the amount of carbon dioxide gas generated by acid decomposition of the formed carrier, 32g of unreacted potassium carbonate remained, and K ₂ O.
It was found that x=0.98 for xAl ₂ O ₃ .

15.0 g of this carrier and 1.0 g of sodium were placed in a stainless steel autoclave, and 30 g of liquefied ammonia was pressurized into the autoclave. After stirring at room temperature for 2 hours, ammonia and hydrogen produced by the reaction were released. Next, 100 ml of n-heptane and 150.0 g of propylene in which 100 ppm by weight of oxygen had been dissolved under pressure were added to the autoclave, and a reaction was carried out at 160°C for 6 hours. The cumulative amount of oxygen to the catalyst due to this reaction was 1.1 mol%. After treatment and analysis in the same manner as in Example 1, the reaction rate of propylene was
34%, selectivity for 4-methyl-1-pentene is 90%
It was hot. The activity was 0.478.

Oxygen-free propylene (oxygen content <
1ppm) was added thereto, and the reaction was carried out again at 160°C for 5 hours. Conclusion of the analysis, the reaction rate of propylene is 36
%, the selectivity of 4-methyl-1-pentene is 90%,
The activity was 0.608.

Comparative Example 2 Under the same conditions as in Example 3, a reaction with oxygen-free propylene was first carried out for 8 hours. Next, the same treatment as in Example 1 was carried out, and the dimerization reaction of propylene was again carried out on the catalyst in the autoclave under exactly the same conditions as in Example 3. As a result of analysis, the reaction rate of propylene was 28%, 4-methyl-1
- The selectivity for pentene was 86% and the activity of the catalyst was 0.452.

Example 4 (See Example 3 for chemical reaction formula) Potassium amide was supported on the carrier obtained in Example 3 by using potassium instead of sodium. The amount of potassium used, the conditions for amide formation, etc. were exactly the same as in Example 3. Using the potassium amide support thus obtained, a reaction was carried out in the same manner as in Example 3 with propylene in which 100 ppm by weight of oxygen had been dissolved under pressure. The cumulative amount of oxygen to the catalyst due to this reaction was 1.8 mol%.
After treatment and analysis in the same manner as in Example 1, the propylene reaction rate was 28%, the 4-methyl-1-pentene selectivity was 89%, and the activity was 0.389.

Example 5 138g of anhydrous potassium carbonate and aluminum hydroxide
A small amount of water was added to 156 g, kneaded well, and formed into pellets with a diameter of 1.6 mm and a length of 5 to 8 mm using an extruder. This was placed in an alumina crucible and fired at 1000°C for 5 hours in an air atmosphere to obtain a carrier. After cooling, the fired product was taken out and the entire carrier was heated to 200°C in a 500ml three-necked flask under a nitrogen gas atmosphere, and while stirring, sodium was added to a concentration of 10wt%, and the mixture was heated for 2 hours. The mixture was stirred to ensure uniform support. The temperature was further raised to 400°C and heating was continued for 2 hours.

A propylene dimerization reaction was carried out using the catalyst thus obtained. That is, this catalyst was packed in a fixed bed reactor, and propylene containing 19 ppm of oxygen was passed through the reactor at LHSV 1.0 hr ^-1 to carry out the reaction. The reaction rate after 80 hours was 46%, 4-methyl-
The selectivity for 1-pentene was 89%. The cumulative amount of oxygen to the catalyst at this point was 0.8% mol. After 800 hours (cumulative amount of oxygen to the catalyst, 8 mol)
%), but the selection rate was still increasing, albeit slowly.

Claims (1)

[Claims] 1. Propylene can be converted into a compound represented by the following formula (1) K ₂ O x Al ₂ O ₃ (1) (where x is
At least one element or compound selected from the group consisting of sodium, potassium, sodium amide, and potassium amide is supported on a carrier whose main component is 0.5≦x≦11. 4-methyl-
A method for producing 4-methyl-1-pentene, characterized in that propylene containing 2 to 500 ppm by weight of oxygen is used as a reaction raw material.