JPH0643349B2 - Method for producing diisopropylnaphthalene - Google Patents

Description

TECHNICAL FIELD The present invention relates to a method for industrially advantageously producing diisopropylnaphthalene, particularly 2,6-diisopropylnaphthalene, from naphthalene and propylene.

(Prior Art) When naphthalene is isopropylated with propylene in the presence of aluminum chloride or a solid acid catalyst, naphthalene monoisopropylate, diisopropylate, triisopropylate or more polyisopropylate and unreacted naphthalene are formed. It is known that things can be obtained. In addition, in this case, in order to increase the yield of diisopropylnaphthalene, in the alkylation reaction using an aluminum chloride catalyst, a method in which a new catalyst is added to the alkylation product after the completion of the alkylation reaction and the mixture is held for a certain period of time (Japanese Patent Laid-Open Publication No. Sho. 52-17452), 2, 6
In order to obtain diisopropylnaphthalene in high yield,
Diisopropylnaphthalene other than 2,6-diisopropylnaphthalene and triisopropylnaphthalene Naphthalene or monoisopropylnaphthalene is added to the above polyisopropylnaphthalene and transalkylated in the presence of a solid acid catalyst to convert it to 2,6-diisopropylnaphthalene. A method (JP-A-62-226931) and the like are also known.

However, when aluminum chloride is used as a catalyst in the alkylation reaction or transalkylation reaction as described above, aluminum chloride forms a complex with an isopropylation product, and thus there is a difficulty in separating the catalyst. There is a problem of equipment corrosion, and further, there is a problem that the amount of high boiling point by-products is large.

On the other hand, when the solid acid catalyst is used, the problems of catalyst separation and equipment corrosion are avoided, but in this case also, there is a problem that a considerable amount of high-boiling substances are by-produced.

(Problems of the invention) The present invention provides a method for producing diisopropylnaphthalene in good yield from naphthalene and propylene by suppressing a by-product of a high boiling point by using a solid acid catalyst, and the efficiency of the process as a whole is improved. It is an object of the present invention to provide a method for industrially producing diisopropylnaphthalene which is excellent and economical.

(Means for Solving the Problems) The present inventors have completed the present invention as a result of intensive studies to solve the above problems.

That is, according to the first process of the present invention, an isopropylation step in which naphthalene or a mixture containing naphthalene is reacted with propylene in the presence of a solid acid catalyst, and an isopropylation product obtained in the isopropylation step is treated with a solid acid. A transalkylation step of reacting in the presence of a catalyst,
It comprises a separation step of separating a diisopropylnaphthalene fraction from the transalkylation product obtained in the transalkylation step, and the isopropylation step comprises 150 to 2
The transalkylation step is carried out at a temperature of 50 ° C. and under a pressure condition in which the existing naphthalene substantially shows a liquid phase, and at a temperature of 250 to 300 ° C., in which the existing naphthalene shows a substantially gas phase. There is provided a method for producing diisopropylnaphthalene, which is characterized in that it is carried out under conditions.

According to the second process of the present invention, the 2,7-isomer after separating the 2,6-isomer from the diisopropylnaphthalene isomer mixture fraction containing 2,6-diisopropylnaphthalene and 2,7-diisopropylnaphthalene is obtained. The mixture containing the body and naphthalene in the presence of a solid acid catalyst at 250-
A transalkylation step (A) in which naphthalene existing at a temperature of 350 ° C. is subjected to a transalkylation reaction at a reaction temperature at which it substantially forms a liquid phase to produce monoisopropylnaphthalene, and monoisopropylnaphthalene or monoisopropylnaphthalene and naphthalene are combined. An isopropylation step of isopropylating a mixture mainly composed of propylene in the presence of a solid acid catalyst at a temperature of 150 ° C. to 250 ° C. and under a pressure condition in which naphthalene present substantially shows a liquid phase; 250-3 in the presence of a solid acid catalyst
A transalkylation step (B) at a temperature of 00 ° C. and a pressure condition in which naphthalene present is substantially in a gas phase, and at least a transalkylation step (B) among the transalkylation products. ) Product,
A step (I) of separating a diisopropylnaphthalene fraction, a low-boiling point fraction less than diisopropylnaphthalene, and a high-boiling point fraction above triisopropylnaphthalene, the 2,6-isomer contained in the separated diisopropylnaphthalene fraction The step (II) of separating the body,
The mixture containing the 2,7-isomer after separating the 6-isomer is circulated as a reaction raw material in the transalkylation step (A), and at least one of the high boiling fractions in the separation step (I) is circulated. Parts are recycled to the transalkylation step (B) and at least a portion of the product of the transalkylation step (A) is recycled to the isopropylation step, the transalkylation step (B) and the separation step (I The method for producing 2,6-diisopropylnaphthalene is characterized in that it is recycled to at least one step of

Next, each step in the first process of the present invention will be described in detail.

[Isopropylation step]

The isopropylation step used in the first process of the present invention is
Propylene is reacted with naphthalene or a mixture containing naphthalene in the presence of a solid acid catalyst. Examples of the solid acid catalyst include silica / alumina, crystalline aluminosilicate, nickel oxide / silica, silver oxide / silica alumina, silica / magnesia, alumina / boria, solid phosphoric acid, aluminum phosphate, zirconium phosphate and the like. To be

The preferred catalyst used in the present invention is a non-zeolitic silica-alumina or zeolite. When zeolite is used, it is preferable to allow a suitable amount of water to coexist in the reaction system. By this isopropylation reaction, the isopropyl group attached to the naphthalene ring is easily rearranged to another naphthalene ring by the transalkylation reaction in the presence of the solid acid catalyst as described above. Therefore, this isopropylation reaction is regarded as a reversible reaction through the transalkylation reaction, and an equilibrium composition exists between naphthalene and isopropylated naphthalenes. The amount of diisopropylnaphthalene produced depends on the ratio of the naphthalene nucleus to the isopropyl group in the reaction, the temperature, the type and amount of the catalyst, and the like.

This isopropylation reaction process is performed at a temperature of 150 to 250 ° C.
It is carried out at 0 ° C. and under pressure conditions in which the naphthalene present is substantially in the liquid phase. The reaction pressure may be normal pressure to 30 kg / cm ² G depending on the reaction temperature. The contact time is 0.02 to 6 hours, preferably 0.4 to 3.5 hours.

In the isopropylation reaction of the present invention, as described above, 15
A pressure condition in which naphthalene exhibits a liquid phase at 0 to 250 ° C. is adopted. By adopting such conditions, the by-product of the high boiling point substance is significantly suppressed. According to the research conducted by the present inventors, the formation of high-boiling substances when a solid acid catalyst is used is significantly promoted by direct contact of gaseous propylene with the solid acid catalyst. It was found that the formation of high-boiling substances was significantly suppressed when the contact with the liquid phase was blocked by liquid-phase naphthalene. Therefore, in this isopropylation step, temperature and pressure conditions in which the naphthalene liquid phase component substantially exists are adopted. Such conditions are preferably found below 250 ° C. A temperature higher than this is disadvantageous because it requires a higher pressure than necessary in order for the side reaction to proceed or the liquid phase of naphthalene to substantially exist. When a solid acid catalyst is used, a gas phase reaction is generally used, but in the case of the present invention, an isopropylation reaction can be smoothly progressed even in a liquid phase reaction. When the reaction temperature is lower than 150 ° C., the reaction rate decreases, and it becomes difficult to carry out a smooth isopropylation reaction.

When a zeolite catalyst (H type) is used as the isopropylation catalyst, it is preferable to allow water to coexist in the reaction system. The coexistence of this water provides advantages such as suppression of coke formation. As a method of adding water to the reaction system, there is a method of adding it to propylene gas or naphthalene which is a reaction raw material in advance, or preferably a method of supplying it as steam to the reaction system. The amount of water in the reaction system is 0.01 to 10 parts by weight, preferably 0.1 to 1 part by weight, based on 100 parts by weight of the liquid phase component.

As the reaction system for carrying out the isopropylation step, a reaction tower filled with a solid acid catalyst is used, and propylene is introduced in a gaseous form from one end thereof and naphthalene or a mixture containing naphthalene is introduced in a liquid form, and It is advantageous to use a distribution system in which the isopropylated product is withdrawn from the end of the.

In the isopropylation step, an isopropylation product containing unreacted naphthalene, monoisopropylnaphthalene, diisopropylnaphthalene, triisopropylnaphthalene and polyisopropylnaphthalene having a higher boiling point than that is obtained.

In the present invention, this isopropylation step is carried out by circulating the low boiling point fraction below monoisopropylnaphthalene obtained in the subsequent step of separating the transalkylation reaction product into the isopropylation reaction step to react with propylene. It can also be carried out. When the isopropylation reaction is carried out by circulating such a fraction, the isopropylation reaction is caused by the reaction of propylene with unreacted naphthalene or monoisopropylnaphthalene constituting the circulated low-boiling fraction, and diisopropyl Naphthalene is produced.

The degree of alkylation in this isopropylation step, that is, the molar ratio of isopropyl groups to naphthalene nuclei in the isopropylation product is usually 0.5 to 2.5, preferably 1.6 to
The range is 2.3. This molar ratio can be adjusted by the reaction time, the rate of introduction of propylene into the isopropylation step, and the like.

[Transalkylation step of isopropylated product]

This transalkylation step is a step of bringing the isopropylation product obtained above into contact with a solid acid catalyst to transfer an isopropyl group bonded to a naphthalene nucleus to another naphthalene nucleus. For example, the reaction between naphthalene or monoisopropylnaphthalene and triisopropylnaphthalene produces diisopropylnaphthalene.
Further, in this transalkylation step, an isomerization reaction of diisopropylnaphthalene occurs in addition to the transalkylation reaction, and the proportion of isomers in diisopropylnaphthalene is maintained at an almost equilibrium composition.

In the present invention, this transalkylation step involves recycling at least a portion of the polyisopropylnaphthalene above the triisopropylnaphthalene obtained in the subsequent separation step (I) to this transalkylation step to yield other naphthalene nuclei. It is preferred to cause a transalkylation reaction to occur.

As the catalyst in this transalkylation step, the same solid acid as shown in the isopropylation step is used, but non-zeolitic silica-alumina or zeolite is preferable.

The reaction temperature in the transalkylation step is 250 ° C.
When a pressure condition in which naphthalene existing at a temperature of up to 300 ° C. substantially shows a gas phase is adopted and the reaction temperature exceeds 300 ° C., a decomposition reaction occurs and the by-product generation rate increases. Further, in the present invention, this transalkylation step is carried out while maintaining the temperature and pressure conditions in which naphthalene substantially exhibits a gas phase as described above. Adoption of such conditions will substantially improve the alkylation degree of the mixture participating in the reaction in the transalkylation step, and in order to avoid side reactions, the alkylation degree should be selected lower in the isopropylation step. However, it is advantageous in that sufficient selectivity can be obtained. The reaction pressure is from atmospheric pressure to 20 kg / cm ² G depending on the reaction temperature, and the solution time is from 0.02 to 6 kg.
It is 0 hr, preferably 0.4 to 3.5 hr. As the reaction system, a reaction tower filled with a solid acid catalyst is used, and from one end thereof, an isopropylation product consisting of a gas-liquid mixture heated to a temperature and pressure condition where naphthalene shows a gas phase is introduced, and the other end It is advantageous to employ a distribution system in which the transalkylation product is withdrawn from the end of the.

This transalkylation step includes the separation step (I) described below.
It is possible to circulate a part of the low-boiling point fraction less than diisopropylnaphthalene and / or a part of the high-boiling point fraction above triisopropylnaphthalene separated in step 1. When a large amount of isopropylnaphthalene or more polyisopropylnaphthalene is present, a by-product such as isopropyltetralin having a structural unit other than an isopropyl group and a naphthalene nucleus is easily generated. Therefore, in order to suppress these byproducts, the degree of alkylation in the transalkylation step,
That is, it is effective to define the molar ratio of isopropyl groups to naphthalene nuclei in the total feed (including the circulating fraction) fed to the transalkylation step. 2.5 or less, preferably 1.6 to 2.
It is preferable to specify it in the range of 2. Above this, the production of the by-products becomes significant.

Further, the production of this by-product becomes remarkable when the reaction time of the transalkylation step becomes longer than necessary. Therefore, the preferable contact time is in the above range. Even if this contact time is short, the separation step (I) of the present invention is performed.
In which the low-boiling fraction and / or the high-boiling fraction in
For the purpose of suppressing the production of by-products, it is preferable to limit the circulating distillate to the distillate consisting of the isopropyl group and the naphthalene nucleus structure as much as possible. For that purpose, it is effective to further separate the low-boiling fraction and / or the high-boiling fraction in the separation step (I) into a light fraction and a heavy fraction, and circulate only each of the separated light fractions. Is.

[Separation Step (I) of Transalkylated Product]

In this step, the transalkylation product of the isopropylation product obtained above is distilled to give a diisopropylnaphthalene fraction, a low boiling fraction less than diisopropylnaphthalene, and a high boiling fraction higher than triisopropylnaphthalene. This is the step of separating. The diisopropylnaphthalene fraction separated in this distillation separation step is treated with the subsequent 2,
It can be fed to the 6-diisopropylnaphthalene separation step (II), and at least a part of the low boiling fraction can be recycled to the transalkylation step or the isopropylation step, preferably to the isopropylation step. Further, at least a part of the high boiling fraction is preferably recycled to the transalkylation step. It is also possible to recover a part of the low boiling fraction and / or the high boiling fraction. It is also a preferred embodiment to separate the low-boiling fraction and / or the high-boiling fraction into a light fraction and a heavy fraction, and circulate only the light fraction. It is a further preferred embodiment that the light fraction of the high boiling fraction is circulated to the transalkylation step and the light fraction of the low boiling fraction is circulated to the isopropylation step.

The diisopropylnaphthalene fraction separated above is the 1,6-isomer, 1,7-isomer, 1,4-isomer, 2,6-isomer, 2,7-isomer, 1 of diisopropylnaphthalene. The main constituents are the .5-isomer, the 1,3-isomer, the 2,3-isomer, especially the 2,6-isomer and the 2,7-isomer.

[Separation step of 2,6-diisopropylnaphthalene (I
I)] This step is a step of separating and recovering the 2,6-isomer from the diisopropylnaphthalene fraction separated in the distillation separation step (I). In this separation step (II),
Although any separation method can be adopted as long as it is a method capable of separating the 2,6-isomer from the diisopropylnaphthalene fraction, generally, a combination of precision distillation and crystallization separation method, a chromatographic separation method, or the like is used. Adopted. For example, in the chromatographic separation method, a liquid phase simulated moving bed separation method can be used.

The diisopropylnaphthalene isomer mixture containing 2,7-isomer as a main component after the 2,6-diisopropylnaphthalene is separated in the separation step (II) can be recovered and used as a solvent or the like. However, in order to increase the production amount of the 2,6-isomer, it is preferable to recycle to the transalkylation step to cause an isomerization reaction.

Next, the first process of the present invention will be described in more detail with reference to the drawings. FIG. 1 shows an example of a flow sheet in the first process of the present invention.

In FIG. 1, raw material naphthalene is supplied to the isopropylation step (IP) through a line 1 together with propylene from a line 2. This isopropylation step (I
In P), the light fraction of the low boiling point fraction of monoisopropylnaphthalene or less, which is separated in the separation step (I), is circulated through the line 4. In this isopropylation step (IP), naphthalene and the light component of its low boiling point fraction are isopropylated with propylene, and the obtained isopropylation product is supplied to the transalkylation step (TA). In this transalkylation step, the isopropylated product is separated in the separation step (I) and is recycled through line 5 to a light fraction of the high boiling point fraction of triisopropylnaphthalene and above and in the separation step (II). The transalkylation process is carried out with the diisopropylnaphthalene fraction, which is circulated through line 6 after separating the 6-isomer. The transalkylated product obtained is sent to the separation step (I).

In the separation step (I), the transalkylation step (TA)
The product is subjected to a distillation treatment to be separated into a diisopropylnaphthalene fraction, a low boiling fraction lower than the diisopropylnaphthalene fraction, and a high boiling fraction higher than triisopropylnaphthalene. Then, the diisopropylnaphthalene fraction is sent to the separation step (II) through the line 3, and the low boiling point fraction is further separated into a light fraction and a heavy fraction below the mononaphthalene fraction in the separation step (I), The light component is circulated to the isopropylation step (IP) through line 4, and the heavy component is withdrawn to the outside of the system through line 9. The high-boiling fraction is further separated into a light fraction and a heavy fraction below the triisopropylnaphthalene fraction in the separation step (I), and the light fraction is circulated to the transalkylation step (TA) through the line 5. The heavy component is extracted from the system through the line 10.

In the diisopropylnaphthalene fraction sent to the separation step (II), the 2,6-isomer is separated here, and is recovered through a line 7. On the other hand, the mixture containing 2,7-isomer as a main component after the 2,6-isomer is separated is recycled to the transalkylation step (TA) through line 6.

The flow sheet shown in FIG. 1 can be modified in various ways. For example, a part of naphthalene supplied from line 1 can be supplied to the transalkylation step (TA), and a part of the low boiling point fraction separated in the separation step (I) can be supplied. It is possible to feed to the transalkylation step (TA).

Next, each step in the second process of the present invention will be described in detail.

[Isopropylation step]

In the second process of the present invention, when 2,6-diisopropylnaphthalene is produced from naphthalene, naphthalene is not directly directly isopropylated but contains, for example, a 2,7-isomer described below as a raw material for isopropylation. A product obtained by transalkylating a diisopropylnaphthalene mixture, a monoisopropylnaphthalene or a mixture containing monoisopropylnaphthalene and naphthalene as a main component such as a low boiling point fraction in the separation step (I) described below is treated with a solid acid catalyst. Use to isopropylate.

This isopropylation step is carried out under the same reaction conditions as the isopropylation step shown above in the first process, and the naphthalene present in the reaction mixture is substantially retained in the liquid phase.

Further, in this isopropylation step, a low boiling point fraction below monoisopropylnaphthalene obtained in the subsequent step of separating the transalkylation reaction product may be circulated to this isopropylation reaction step and reacted with propylene. When the isopropylation reaction is carried out by circulating such a fraction, the isopropylation reaction is caused by the reaction of propylene with unreacted naphthalene and monoisopropylnaphthalene constituting the circulated low-boiling fraction, and diisopropyl Naphthalene is produced.

[Transalkylation step of isopropylated product
(B)] This transalkylation step (B) is a step of bringing the isopropylation product obtained above into contact with a solid acid catalyst to transfer the isopropyl group bonded to the naphthalene nucleus to another naphthalene nucleus. , Under the same transalkylation conditions as shown in the first process above, and the naphthalene present is kept substantially in the gas phase.

Further, in this transalkylation step (B), at least a part of the high-boiling point substance of triisopropylnaphthalene or higher obtained in the subsequent separation step (I) is circulated to this transalkylation step (B) to remove isopropyl groups. It causes a reaction that moves to another naphthalene nucleus.

[Transalkylation treatment step (A) of 2,7-diisopropylnaphthalene and naphthalene] In the second process of the present invention, 2,7-diisopropylnaphthalene after separation of 2,6-diisopropylnaphthalene from the subsequent diisopropylnaphthalene isomer fraction is separated. A transalkylation reaction of the isomer mixture containing diisopropylnaphthalene with naphthalene. This transalkylation process
(A), unlike the transalkylation step (B), since it actively reacts naphthalene in a state of low alkylation degree, as a catalyst, the same solid as the transalkylation step (B). Acid catalysts, preferably non-zeolitic silica-alumina or zeolites are used. The reaction temperature is 250 to 350 ° C., and the conditions under which naphthalene substantially exhibits a liquid phase are used. The reaction pressure is atmospheric pressure to 50 kg / cm ² G depending on the reaction temperature. In this transalkylation step (A), a higher temperature is usually adopted than in the transalkylation step (B). This transalkylation reaction step (A) can be operated in the same manner as the transalkylation step shown in the above-mentioned first process. However, supplying polyisopropylnaphthalene over triisopropylnaphthalene to this transalkylation step (A) is very disadvantageous and should be avoided. This is because diisopropylnaphthalene, including 2,7-diisopropylnaphthalene, undergoes transalkylation with polyisopropylnaphthalene in the presence of polyisopropylnaphthalene and inhibits the progress of efficient transalkylation with naphthalene. In the transalkylation reaction involving polyisopropylnaphthalene, the latter separation step (I) is intensively performed.
The by-products appearing as heavy components of the low boiling point fraction and heavy components of the high boiling point fraction that are to be separated in the process and discharged to the outside of the system are produced. In this transalkylation step (A), 2,7-
A transalkylation reaction occurs between the diisopropylnaphthalene isomer containing diisopropylnaphthalene and naphthalene to produce monoisopropylnaphthalene.
In this transalkylation step (A), at least a portion of less than diisopropylnaphthalene separated in the subsequent distillation separation step (I) may be circulated and reacted, but the product may be reacted in the subsequent isopropylation step or It should be selected so as to be a preferable raw material for the transalkylation step (B) or the separation step (I). The degree of alkylation in this transalkylation step (A), ie the molar ratio of isopropyl groups to naphthalene nuclei in the total feed, is usually 0.5 to 1.6, preferably 0.8 to 1.4. Is the range.

[Separation Step (I) of Transalkylated Product]

In this step, the transalkylation product of the isopropylation product obtained above and the mixture containing the transalkylation product and / or 2,7-diisopropylnaphthalene and naphthalene is distilled to obtain a diisopropylnaphthalene fraction, This is a step of separating a low-boiling point fraction less than diisopropylnaphthalene and a high-boiling point fraction higher than triisopropylnaphthalene. The diisopropylnaphthalene fraction separated in this distillation separation step is supplied to the subsequent 2,6-diisopropylnaphthalene separation step (II), and at least a part of the low boiling point fraction is converted into the transalkylation treatment step (A). To / and (B) to / and can be recycled to the isopropylation step, preferably to the isopropylation step. Further, at least a part of the high boiling fraction is recycled to the transalkylation step (B). It is also possible to recover a part of the low-boiling fraction and / or the high-boiling fraction. It is also a preferred embodiment to separate the low-boiling fraction and / or the high-boiling fraction into a light fraction and a heavy fraction, and to circulate only the light fraction. It is a further preferred embodiment that the light fraction of the high boiling point fraction is circulated to the transalkylation step (B) and the light fraction of the low boiling point fraction is circulated to the isopropylation treatment step.

The diisopropylnaphthalene fraction separated above is the 1,6-isomer, 1,7-isomer, 1,4-isomer, 2,6-isomer, 2,7-isomer, 1 of diisopropylnaphthalene. The main constituents are the .5-isomer, the 1,3-isomer, the 2,3-isomer, especially the 2,6-isomer and the 2,7-isomer.

[Separation step of 2,6-diisopropylnaphthalene (I
I)] This step is a step of separating and recovering the 2,6-isomer from the diisopropylnaphthalene fraction separated in the distillation separation step (I). In this separation step (II),
Any separation method can be adopted as long as it can separate the 2,6-isomer from the diisopropylnaphthalene fraction.

The diisopropylnaphthalene isomer mixture containing 2,7-isomer as a main component after the 2,6-diisopropylnaphthalene is separated in the separation step (II) is recycled to the transalkylation step (A) using the naphthalene. And undergoes a transalkylation reaction with naphthalene.

Next, the second process of the present invention will be described in more detail with reference to the drawings. FIG. 2 shows an example of a flow sheet in the second process of the present invention.

In FIG. 2, raw material naphthalene is supplied to the transalkylation step (A) through line 1. Further, the transalkylation step (A) is supplied with a mixture containing 2,7-diisopropylnaphthalene separated in the separation step (II) and circulated through the line 6. In this transalkylation step (A), the feeds are transalkylated and the resulting product is sent via line 8 to the isopropylation step (IP).

In the isopropylation step (IP), propylene is supplied through a line 2 and separated in a separation step (I), and a light fraction of a low boiling point fraction of monoisopropylnaphthalene or lower is supplied through a line 4. To be done. In this isopropylation step (IP), the light fraction of the low boiling point fraction and the product of the transalkylation treatment step (A) are isopropylated with propylene, and the obtained isopropylation product is B), where the isopropylation product is separated in the separation step (I) and is transalkylated with the light fraction of the higher boiling fraction of triisopropylnaphthalene, which is circulated through line 5. . The transalkylated product obtained is sent to the separation step (I).

In the separation step (I), the product of the transalkylation step (B) is subjected to a distillation treatment to obtain a diisopropylnaphthalene fraction, a low boiling point fraction less than the diisopropylnaphthalene fraction, and a high boiling point fraction equal to or higher than triisopropylnaphthalene. Is separated into Then, the diisopropylnaphthalene fraction is sent to the separation step (II) through the line 3, and the low boiling point fraction is further separated into a light fraction and a heavy fraction below the mononaphthalene fraction in the separation step (I), The light component is circulated to the isopropylation step (IP) through line 4, and the heavy component is withdrawn to the outside of the system through line 9. The high-boiling fraction is further separated into a light fraction and a heavy fraction below the triisopropylnaphthalene fraction in the separation step (I), and the light fraction is circulated through the line 5 to the transalkylation step (B), The heavy component is extracted from the system through the line 10.

In the diisopropylnaphthalene fraction sent to the separation step (II), the 2,6-isomer is separated here, and is recovered through a line 7. On the other hand, the mixture containing 2,7-isomer as a main component after the 2,6-isomer has been separated is recycled to the transalkylation step (A) through line 6.

The flow sheet shown in FIG. 1 can be modified in various ways. For example, transalkylation step (A)
The product of can be fed to the separation step (I), can be fed to the transalkylation step (B), and can also be fed using a plurality of these three feed lines simultaneously. It is also possible to do so. Further, a part of naphthalene supplied from line 1 is subjected to isopropylation step (IP) and / or transalkylation step (B).
Can also be supplied to the separation step (I)
It is possible to feed part of the low-boiling fraction separated in step (b) to the transalkylation step (A) and / or (B). Further, among the low boiling point fractions separated in the separation step (I), the naphthalene fraction is sent to the transalkylation step (A), and the monoisopropyl fraction is converted into the isopropylation step (I).
It can also be sent to P).

[Effect]

In the present invention, naphthalene and propylene are used as raw materials, and by controlling the by-products of high-boiling substances, diisopropylnaphthalene can be efficiently produced. In the case of the present invention, the isopropylated product is directly sent to the transalkylation step, where the transalkylation reaction and the isomerization reaction of diisopropylnaphthalene are carried out, so that the ratio of diisopropylnaphthalene in the transalkylation product and 2, High proportion of 6-isomer. Therefore, the ratio of the low boiling point component and the high boiling point component separated and circulated in the separation step is small, and the present invention improves the efficiency and economical efficiency of the entire process.

〔Example〕

 Next, the present invention will be described in more detail with reference to Examples.

The symbols shown below indicate the following contents.

MIPNP ... Monoisopropylnaphthalene DIPNP ... Diisopropylnaphthalene TIPNP ... Triisopropylnaphthalene TEIPNP ... Tetraisopropylnaphthalene The degree of isopropylation means the molar ratio of the isopropyl side chain to the naphthalene nucleus.

High-boiling substances indicate components with boiling points of 400 ° C or higher, and by-products are
Compounds other than naphthalene and diisopropylnaphthalene are shown.

Example 1 [Isopropylation Step] A reaction tower filled with hydrogen type Y-type zeolite (HY zeolite) was used as a reaction apparatus, and naphthalene and propylene were added from the upper part in a ratio of 2 mol of propylene to 1 mol of naphthalene. It was introduced and circulated in the reaction tower. At the same time, steam was introduced from the upper part of the reaction tower at a ratio of 1% by weight with respect to naphthalene.

The isopropylated product was extracted from the lower part of the reaction tower. In this way, the isopropylation reaction was carried out at various temperatures.
In this case, the liquid hourly space velocity (LHSV) of naphthalene was 1.
It was set to ⁰ hr ⁻¹ . The activity was measured by the conversion rate of propylene. The results of this reaction are shown in Table 1.

[Transalkylation Step] The isopropylation product (the product at a reaction temperature of 180 ° C.) was introduced from the upper part of the reaction column packed with HY zeolite in the same manner as in Example 1 to carry out the transalkylation. The transalkylation reaction was performed so that the product was extracted from the bottom. In this case, the reaction temperature is 210 ° C to 285.
C., LHSV of the reaction raw material was set to 0.5 hr ⁻¹ .
The results are shown in Table-2.

For comparison, the same experiment was performed except that the reaction temperature was 310 ° C. The results are also shown in Table 2.

Example 2 An isopropylation reaction (without addition of steam) and a transalkylation reaction of the obtained isopropylation product were performed in the same manner as in Example 1 except that silica / alumina was used as the catalyst. The isopropylation reaction results are shown in Table 3 and the transalkylation reaction results are shown in Table 4, respectively.

Example 3 100 parts by weight of naphthalene was added with 100 parts by weight of triisopropylnaphthalene containing 2,7-diisopropylnaphthalene as a main component, and naphthalene was in a liquid phase at a reaction temperature of 240 ° C. and a pressure of 5 kg / cm ² G (nitrogen). The transalkylation reaction was carried out in the same manner as the transalkylation of Example 1 under the condition of pressurization). The results are shown in Table-5.

[Brief description of drawings]

FIG. 1 shows an example of a flow sheet for carrying out the first process of the present invention, and FIG. 2 shows an example of a flow sheet for carrying out the second process of the present invention. IP: Isopropylation process TA, A, B: Transalkylation process I, II: Separation process.

─────────────────────────────────────────────────── ─── Continuation of the front page (51) Int.Cl. ⁵ Identification number Office reference number FI technology display location B01J 29/08 C07B 61/00 300 (72) Inventor Tachibaku Dodo 1-1, Marunouchi, Chiyoda-ku, Tokyo No. 2 Japan Steel Pipe Co., Ltd. (72) Inventor Kazuhiko Tate 1-2-1, Marunouchi, Chiyoda-ku, Tokyo Japan Steel Pipe Co., Ltd. (72) Hiroaki Taniguchi 1-2-1, Marunouchi, Chiyoda-ku, Tokyo Nippon Steel Tube Co., Ltd.

Claims (8)

[Claims] 1. An isopropylation step in which naphthalene or a mixture containing naphthalene is reacted with propylene in the presence of a solid acid catalyst, and an isopropylation product obtained in the isopropylation step is reacted in the presence of a solid acid catalyst. A transalkylation step and a separation step of separating a diisopropylnaphthalene fraction from the transalkylation product obtained in the transalkylation step, the isopropylation step being carried out at a temperature of 150 ° C. to 250 ° C. Is carried out under a pressure condition that substantially represents a liquid phase, and the transalkylation step is performed at 250 to 300
A method for producing diisopropylnaphthalene, which is characterized in that it is carried out at a temperature of ° C and under a pressure condition in which naphthalene present is substantially in a gas phase. 2. The method according to claim 1, wherein 2,6-diisopropylnaphthalene is separated from the diisopropylnaphthalene fraction separated in the separation step. 3. The process according to claim 2, wherein diisopropylnaphthalene after the 2,6-diisopropylnaphthalene is separated is recycled to the transalkylation step. 4. In the separation step, in addition to the diisopropylnaphthalene fraction, a fraction having a lower boiling point than the diisopropylnaphthalene fraction and a fraction having a higher boiling point than the diisopropylnaphthalene fraction are separated, and the low boiling point fraction is separated. 4. A method according to any one of claims 1 to 3, wherein at least a part of the high boiling fraction is recycled to the alkylation step and / or the transalkylation step, and at least a part of the high boiling fraction is recycled to the transalkylation step. 5. The method according to claim 1, wherein the range of the degree of alkylation in the transalkylation step is 1.6 to 2.2. 6. A diisopropylnaphthalene isomer mixture containing 2,6-diisopropylnaphthalene and 2,7-diisopropylnaphthalene. After separating the 2,6-isomer from the distillate fraction, the mixture containing the 2,7-isomer and naphthalene are separated. A transalkylation step (A) in which a naphthalene existing at a temperature of 250 to 350 ° C. in the presence of a solid acid catalyst is subjected to a transalkylation reaction under a pressure condition in which a substantially liquid phase is formed to produce monoisopropylnaphthalene; Isopropylation in which isopropylnaphthalene or a mixture mainly composed of monoisopropylnaphthalene and naphthalene is isopropylated with propylene at a temperature of 150 to 250 ° C. in the presence of a solid acid catalyst and at a pressure condition in which the present naphthalene shows a substantially liquid phase. And the isopropylation product in the presence of a solid acid catalyst 25 A transalkylation step (B) at a temperature of up to 300 ° C. and a pressure condition in which naphthalene present is substantially in a gas phase, and at least a transalkylation step (B) of each of the transalkylation products ( The step (I) of separating the product of B) into a diisopropylnaphthalene fraction, a low-boiling fraction lower than diisopropylnaphthalene, and a high-boiling fraction higher than triisopropylnaphthalene, from which the separated diisopropylnaphthalene fraction is The step (II) of separating the contained 2,6-isomers, and the mixture containing the 2,7-isomers after separating the 2,6-isomers is subjected to the transalkylation step (A). While circulating as a reaction raw material, at least a part of the high boiling point fraction of the separation step (I) is circulated to the transalkylation step (B), and At least a part of the product of the step alkylation step (A) is recycled to at least one of the isopropylation step, the transalkylation step (B) and the separation step (I). A method for producing diisopropylnaphthalene. 7. At least one of the low boiling point fraction separated in the separation step (I) is at least one of a transalkylation step (A), a transalkylation step (B) and an isopropylation treatment step. 7. The method of claim 6, wherein 8. The low-boiling fraction and the high-boiling fraction separated in the separation step (I) are further separated into a light fraction and a heavy fraction, and the light fraction of the high-boiling fraction is converted into the trans fraction. 7. The process of claim 6 wherein the low boiling fraction light fraction is recycled to the alkylation step (B) and the low boiling fraction light fraction is recycled to the isopropylation step.