JPH0639434B2 - Method for separating 2,7- and 2,6-diisopropylnaphthalene - Google Patents

Description

TECHNICAL FIELD The present invention relates to a mixture of diisopropylnaphthalene isomers,
The present invention relates to a method for separating 7- and 2,6-isomers with high purity.

(Prior Art and its Problems) Polyesters obtained from 2,7-naphthalenedicarboxylic acid and 2,6-naphthalenedicarboxylic acid are disclosed in JP-A-58-162630.
As described in No. 6, since it is a liquid crystal polymer, which is a polymer having a high liquid crystallinity and strong mechanical properties that are well-balanced as a whole, 2,7- and 2,6 are used as polyester raw materials. -Establishment of a method for industrially producing naphthalenedicarboxylic acid is desired.

2,7- and 2,6-naphthalenedicarboxylic acid are 2,7- and 2,6-obtained by alkylating naphthalene with propylene.
It can be produced by oxidizing diisopropylnaphthalene.

However, the diisopropylnaphthalene fraction of the isopropylation product obtained by alkylating naphthalene with propylene is an isomer mixture containing various isomers in addition to the 2,7-isomer, and thus 2,7- And 2,
It cannot be used as a raw material for 6-naphthalenedicarboxylic acid, and from its diisopropylnaphthalene isomer mixture,
It is necessary to separate the 2,7-isomer and the 2,6-isomer with high purity, but conventionally, the 2,7-isomer and the 2,6-isomer have been separated from such a diisopropylnaphthalene isomer mixture. No industrial technology has been established to separate the bodies in high purity.

The present inventors have previously proposed a technique for separating 2,6-diisopropylnaphthalene by a two-stage adsorption separation method (Japanese Patent Application No. 63-24788). This separation method gives a diisopropylnaphthalene mixture containing 1,7-isomer and 2,7-isomer in addition to 2,6-diisopropylnaphthalene. However, since this separation method is a technique for recovering 2,6-diisopropylnaphthalene with high purity, it has an intermediate strength of adsorptivity existing between the 2,7-isomer and the 2,6-isomer. 1,5-isomers, 1,6-isomers, 1,4-isomers and 2,3-isomers are 2,7-
It is mixed in the isomers, and these isomers cannot be separated by distillation because their boiling points are close to that of the 2,7-isomer, and it is not possible to obtain highly pure 2,7-diisopropylnaphthalene. It is impossible.

(Problem of the Invention) The present invention relates to a diisopropylnaphthalene isomer mixture.
It is an object of the present invention to provide an industrially advantageous method capable of separating 2,7- and 2,6-isomers with high purity.

(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, when separating 2,7- and 2,6-diisopropylnaphthalene from a diisopropylnaphthalene isomer mixture, the mixture is subjected to a distillation treatment to give 1,7- and 1, The first step of separating the 3-isomer and the 1,7- and 1,3-isomer-free diisopropylnaphthalene isomer mixture obtained in the first step were selectively adsorbed to the 2,7-isomer. By adsorption separation treatment using a zeolite adsorbent and a desorbent, and an extract containing a 2,7-isomer,
2,7- and 2,6 comprising a second step for obtaining a raffinate containing a 2,6-isomer and a third step for separating the 2,6-isomer contained therein from the raffinate -A method for separating diisopropylnaphthalene is provided. Also, according to the second process of the present invention, when separating 2,7- and 2,6-diisopropylnaphthalene from a diisopropylnaphthalene isomer mixture, the mixture is converted into 2,7- and 1,7-isomers. Adsorption and separation treatment using a zeolite adsorbent and a desorbent exhibiting selective adsorption to obtain an extract containing 2,7- and 1,7-isomers and a raffinate containing 2,6-isomers 1
And a second step in which the extract obtained in the first step is subjected to a distillation treatment to separate the 2,7-isomer and the 1,7-isomer to obtain the 2,7-isomer. A method for separating 2,7- and 2,6-diisopropylnaphthalene is provided, which comprises the step of separating the 2,6-isomer contained therein from the raffinate obtained in the first step. It

The diisopropylnaphthalene isomer mixture in the present invention is obtained by isopropylating naphthalene with propylene,
It can be obtained by separating a diisopropylnaphthalene fraction from the obtained product. The naphthalene used as a raw material for isopropylation may be any kind of substance produced from petroleum-based oil, coal-based oil, or the like. However,
When a component that becomes a catalyst poison to the isopropylation catalyst, such as a sulfur compound or a nitrogen compound, is contained, these compounds are prepared by a conventionally well-known purification technique, hydrorefining, activated clay treatment, or the like. Is preferably removed. The isopropylation reaction is a well-known reaction, and is carried out as a liquid phase or gas phase reaction according to a conventionally known method. As the catalyst, silica / alumina, crystalline aluminosilicate, nickel oxide / silica, silver oxide / silica alumina, silica / magnesia, alumina /
Solid acid catalysts such as boria and solid phosphoric acid, and Friedel-Crafts catalysts such as aluminum chloride, hydrogen fluoride and phosphoric acid are used. In 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 above-mentioned alkylation reaction catalyst. Therefore, this isopropylation reaction is regarded as a reversible reaction through the transalkylation reaction, and an equilibrium composition exists between naphthalene and isopropylnaphthalenes. The amount of diisopropylnaphthalene produced depends on the ratio of naphthalene to propylene in the reaction, the temperature, the type and amount of the catalyst, and the like.

When carrying out the isopropylation reaction using a Friedel-Crafts catalyst, the reaction is carried out at room temperature to 150 ° C, preferably 50 to 100 ° C.
Temperature, pressure from normal pressure to 10 atmospheres, catalyst ratio to raw material
The condition is 0.05 to 1.0, preferably 0.08 to 0.5. In order to increase the yield of diisopropylnaphthalene, the molar ratio of isopropyl groups to naphthalene nuclei in the total alkylation product is 0.5 to 3.0, preferably 1.0 to 2.5. When using a solid acid catalyst, the reaction temperature is 150 to 500.
C, pressure 0 to 50 kg / cm ² G, contact time 0.02 to 6.0 hr, preferably in the range of 200 to 350 ° C., pressure 0 to 35 kg / cm ² G,
The contact time is 0.4 to 2.5 hours. When the temperature is high or the contact time is long, a decomposition reaction occurs and a by-product is produced. Further, when the temperature is low or the contact time is short, the yield of diisopropylnaphthalene is lowered. In this isopropylation reaction step, an isopropylated product containing unreacted naphthalene, monoisopropylnaphthalene, diisopropylnaphthalene, triisopropylnaphthalene and more polyisopropylnaphthalene is obtained, and the proportion of diisopropylnaphthalene in it is usually 10
~ 50% by weight.

Next, the isopropylation product obtained in the isopropylation reaction step is subjected to a distillation treatment to separate a diisopropylnaphthalene fraction. By this distillation treatment, generally, a low-boiling fraction consisting of naphthalene and monoisopropylnaphthalene, a diisopropylnaphthalene fraction,
It is separated into a high-boiling-point fraction consisting of triisopropylnaphthalene and higher polyisopropylnaphthalene. Monoisopropylnaphthalene can be converted to diisopropylnaphthalene by isopropylating it with propylene, and polyisopropylnaphthalene having triisopropylnaphthalene or higher can be transalkylated with naphthalene to give diisopropylnaphthalene. can do.

The diisopropylnaphthalene fraction obtained above is a diisopropylnaphthalene 2,7-isomer, as well as a 1,3-isomer, 1,
7-isomer, 1,4-isomer, 2,6-isomer, 1,6-isomer, 1,5-isomer
It includes isomers such as isomers and 2,3-isomers. According to the study by the present inventors, among these isomers, 2,7-isomer and 1,7-isomer were found for the zeolite adsorbent.
It was found that the isomers showed similar adsorption behavior and showed selective adsorption as a strongly adsorbed component, and, advantageously, the 2,7-isomer (boiling point 317 with this same adsorption behavior
C) and 1,7-isomer (boiling point 309 ° C) can be separated by distillation. Therefore, by combining the distillation treatment before or after the adsorption treatment, the 2,7-isomer with high purity can be obtained. It was found that they can be separated and collected.

As the diisopropylnaphthalene isomer mixture used as a raw material in the present invention, the diisopropylnaphthalene fraction obtained by subjecting the isopropylated product of naphthalene to a distillation treatment can be used as it is, or the diisopropylnaphthalene fraction can be obtained by an isomerization treatment. The isomerization products obtained can be used. The isomerization products are 2,7- and 2,6-
It contains about 80% by weight of isomers, in which the proportion of 2,7-isomer and 2,6-isomer is approximately 1: 1. Therefore, this isomerization product is suitable as a raw material of the present invention. The isomerization of the diisopropylnaphthalene fraction can be carried out using the same catalyst and reaction conditions as those shown in the above isopropylation step.

The zeolite adsorbent used in the present invention includes 2,7-isomer and 1,
It shows adsorptivity selectively to the 7-isomer, a faujasite-type zeolite adsorbent is used, and a metal-substituted Y-type zeolite is preferably used. In this case, as the substitution metal, an alkali metal or an alkaline earth metal is used,
Particularly, potassium is preferable.

When a mixture of diisopropylnaphthalene isomers is subjected to adsorption treatment with a zeolite adsorbent, the strength of the adsorption force based on the 2,7-isomer of the diisopropylnaphthalene isomer with respect to the zeolite adsorbent has a relative separation coefficient β (2,7 / It is represented by i) and is represented by the following equation.

β (2,7 / i) ＝ K (2,7) / K (i) (I) where K (2,7) and K (i) are solid-liquid of 2,7-isomer, respectively. The equilibrium constant and the solid-liquid equilibrium constant of the isomer i are shown and defined by the following formula.

An isomer whose relative separation coefficient β (2,7 / i) is less than 1 is
It shows that it is more easily adsorbed than the 2,7-isomer, and conversely, isomers larger than 1 are less likely to be adsorbed than the 2,7-isomer. The relative separation factor β (2,7 / 1,7) of 1,7-isomer for zeolite adsorbent is almost 1, and the relative separation factor β (2,7 / i) of other isomers is 1 Indicates a larger value. Therefore, by using the zeolite adsorbent, the 2,7- and 1,7-isomers can be selectively adsorbed and separated from the diisopropylnaphthalene isomer mixture. In the present invention, it is preferable to use a zeolite adsorbent having a relative separation coefficient β (2,7 / i) of isomers other than 2,7- and 1,7-isomers of 2 or more.

As the desorbent used in the present invention, a substance having a capability of adsorbing to the zeolite adsorbent promptly and desorbing the substance already adsorbed may be used. In the present invention, the aromatic desorbent is preferably used. Particularly preferred desorbents are alkylbenzenes represented by the following general formula.

In the above formula, R and R'represent a methyl group, an ethyl group, an n-propyl group or an isopropyl group, and n is 0 or 1.

As the desorbent D used in the present invention, the value of the relative separation coefficient β (2,7 / D) of the desorbent defined in the same manner as in the case of the diisopropylnaphthalene isomer i is 0.5 to 3, preferably 1 to
It is preferable to use those in the range of 2. If the value of the relative separation coefficient β (2,7 / D) of this desorbent is too large, a very large amount of desorbent is required.One method, if it is too small, it is necessary to increase the amount of zeolite adsorbent used. Therefore, it is not economically preferable.

The adsorptive separation according to the present invention is carried out by an adsorptive separation technique by a chromatographic method, and although it can be carried out by a fixed bed or a moving bed, it is preferably carried out by a countercurrent type simulated moving bed system. The adsorption separation technology using the simulated moving bed method
It is an already established technique and is applied to adsorption separation of a xylene isomer mixture, and is described in, for example, Japanese Patent Publication No. 42-15681 and Japanese Patent Publication No. 50-10547.

Next, the adsorption separation technology by the countercurrent type simulated moving bed method will be described in detail. In this adsorption / separation technique, as basic operations, four operations including a desorption operation, a concentration operation, an adsorption operation, and a desorbent recovery operation are simultaneously and continuously performed. FIG. 1 shows a schematic diagram of an adsorption separation device using a simulated moving bed. In this figure, 1 to 16 are adsorption chambers containing a zeolite adsorbent, which are connected to each other. 17 is a desorbent supply line, 18 is an extract extraction line, 19 is a raw material supply line, 20 is a raffinate extraction line, and 21 is a recycle line. Adsorption chambers 1-16 shown in the drawing and each line 17-21
In this arrangement state, the desorption operation is performed in the adsorption chambers 1 to 3, the concentration operation is performed in the adsorption chambers 4 to 8, the adsorption operation is performed in the adsorption chambers 9 to 13, and the desorbent recovery operation is performed in the adsorption chambers 13 to 16, respectively.

In such a simulated moving bed, each supply and extraction line is moved by one valve in the liquid flow direction by one adsorption chamber at regular time intervals. Therefore, in the next arrangement state of the adsorption chambers, the desorption operation in the adsorption chambers 2 to 4, the adsorption chambers 5 to 9
The concentration operation, the adsorption operation in the adsorption chambers 10 to 14, and the desorbent recovery operation in the adsorption chambers 15 to 1 are performed. By carrying out such an operation successively in succession, the adsorption separation treatment of the diisopropylnaphthalene isomer mixture by the simulated moving bed is achieved.

Next, the role of each operation will be described.

(i) Desorption operation The adsorbent adsorbing the concentrated 2,7-isomer (or 2,7-isomer and 1,7-isomer, hereinafter simply referred to as 2,7-isomer) is Contact with the desorbent in this operating zone. The 2,7-isomer is
It is desorbed from the adsorbent by the desorbent and collected as an extract. When the liquid flow rate in this zone is too small and the desorption of the 2,7-isomer is insufficient, the 2,7-isomer is adsorbed on the adsorbent and circulates, and is mixed with the raffinate. The 7-isomer recovery is reduced. Therefore, the ratio of the liquid flow rate to the adsorbent flow rate in this operation zone needs to be a certain value or more, and it is preferable to satisfy the following equation.

(ii) Concentration operation Components other than the 2,7-isomer adsorbed on the adsorbent are completely desorbed in this operation zone, and only the 2,7-isomer is concentrated and recovered as an extract. If the liquid flow rate in this zone is too low and the desorption of components other than the 2,7-isomer is insufficient, these isomers will be mixed in the extract and
Reduces the purity of isomers. Therefore, the ratio of the liquid flow rate to the adsorbent flow rate in this operation zone needs to be a certain value or more, and it is preferable to satisfy the following equation.

(iii) Adsorption operation The 2,7-isomer contained in the raw material comes into contact with the adsorbent in this operation zone and is adsorbed and then selected in the concentration operation zone. 2,
Components other than the 7-isomer are recovered with the desorbent as a raffinate stream. Liquid flow rate in this zone is too high, 2,7-
If the adsorption of the isomer on the adsorbent is insufficient, the 2,7-isomer will be mixed in the raffinate and the recovery of the 2,7-isomer will be reduced. Therefore, the ratio of the liquid flow rate to the adsorbent flow rate in this operation zone needs to be below a certain fixed value, and it is preferable to satisfy the following equation.

(iv) Desorbing agent recovery operation Isomers other than the 2,7-isomer are completely adsorbed on the adsorbent, and these components are recovered from the raffinate. A desorbent containing no diisopropylnaphthalene isomer is recovered from the lowest part of this operation zone and circulated to the desorbent operation zone. Therefore, if the liquid flow rate in this zone is too large, the weakly adsorbing component is not adsorbed by the adsorbent, mixes with the desorbent and circulates, and flows out into the extract, resulting in the purity of the 2,7-isomer. Lower. If the liquid flow rate in this zone is too low, the weakly adsorbing components existing in the liquid between the adsorbent particles in the adsorption chamber move with the movement of the adsorption chamber and become mixed in the extract. -Reduce the purity of isomers. Therefore, it is necessary to set the liquid flow rate in this zone within a certain range, and it is preferable to satisfy the following equation.

In the above formula, L (I), L (II), L (III) and L (IV) are desorption operation zone (i), concentration operation zone (ii) and adsorption operation zone (ii), respectively.
The liquid flow rate (cc / hr) flowing through i) and the desorption recovery operation zone (iv) is shown. S (I), S (II), S (III) and S (IV) are desorption operation zone (i), concentration operation zone (ii), adsorption operation zone (iii), respectively.
And adsorbent flow rate (cc / hr) moving in the desorbent recovery operation zone
Indicates.

Next, a flow sheet of the first process of the present invention is shown in FIG. In FIG. 2, 31 is a distillation column, 32 is an adsorption separation device, and 38 is a 2,6-isomer separation device. The diisopropylnaphthalene isomer mixture is introduced into the distillation column 31 through line 33, where the 1,7-isomer of the isomer mixture is
The 1,3-isomer was separated as overhead and the 2,7-isomer and 2,
The remaining isomer mixture, including the 6-isomer, is introduced into the adsorptive separator 32 via line 35.

In the adsorption / separation device 32, the adsorbed component is separated into the 2,7-isomer and the weakly absorbable component other than the isomer, and the 2,7-isomer is extracted and passed through the line 36. Extracted and other isomers are lined up as a ryffinate
It is withdrawn through 37 and introduced into the 2,6-isomer separation device 38. In the 2,6-isomer separation device 38, the 2,6-isomer is selectively separated from the isomer mixture contained in the raffinate,
It is withdrawn through line 39 and the remaining isomer mixture is submitted through line 40.

Next, a flow sheet of the second process of the present invention is shown in FIG.

The diisopropylnaphthalene isomer mixture is introduced through line 33 to an adsorption separator 32, where the strongly adsorbing components 2,7-isomer and 1,7-isomer and the weakly adsorbing component. It is separated into other isomers. 2,7-isomer and 1,
The 7-isomer is extracted as an extract through line 36, the other isomers as raffinate at line 37.
Be pulled out through. The extract containing the 2,7-isomer and the 1,7-isomer is introduced into the distillation column 31, where the 1,7-isomer is separated as a top product and the 2,7-isomer is the bottom product. It is separated as a thing.

The raffinate extracted from the adsorption / separation device 32 is introduced into the 2,6-isomer separation device 38. In this 2,6-isomer separation device, the 2,6-isomer is selectively separated from the isomer mixture contained in the raffinate, and extracted through a line 39,
The remaining isomer mixture is withdrawn through line 40.

As the separation technique in the above-mentioned 2,6-isomer separation device, various conventionally known methods are adopted. As such a method, a separation method by a cooling crystallization operation (Japanese Patent Laid-Open No. 62-226) is used.
931), a clathrate separation method by addition of thiourea (JP-A-63-88)
141) and the like, as well as a two-stage adsorption separation method using a zeolite adsorbent (Japanese Patent Application No. 63-24788). Since the isomer mixture separated as a raffinate from the adsorption / separation device does not contain 2,7-isomers having similar properties, it is relatively easy to separate the 2,6-isomers contained therein, as described above. Various various separation techniques can be applied.

(Effect of the Invention) According to the present invention, 2,7-diisopropylnaphthalene and 2,6-diisopropylnaphthalene can be simultaneously separated and recovered in high purity from a diisopropylnaphthalene isomer mixture.

The 2,7- and 2,6-diisopropylnaphthalene obtained by the present invention is used as a starting material for 2,7- and 2,6-naphthalenedicarboxylic acid, which is a polyester raw material, and is also used as various solvents. .

(Example) Next, the present invention will be described in more detail with reference to examples.

Example 1 (I) Distillation treatment Diisopropylnaphthalene mixture having the composition shown in Table 1 obtained by isopropylating naphthalene with propylene about 1.
5 was subjected to distillation treatment by a batch distillation column packed with McMahon packing having an inner diameter of 20 mm and a height of 1800 mm. The pressure during distillation was 50 mmHg and the reflux ratio was 20. As a result, about 0.85 of an isomer mixture having the composition shown in Table 2 in which 1,3- and 1,7-isomers were removed from the diisopropylnaphthalene mixture was obtained.

(II) Adsorption Separation Treatment An adsorption separation experiment was conducted using the diisopropylnaphthalene isomer mixture having the composition shown in Table 2 as a raw material. The adsorbent used in the adsorption separation experiment was Na-type Y-type zeolite (SiO ₂ / A
₂ O ₃ molar ratio: 4.6, particle size: 40-80 mesh) is ion-exchanged with a predetermined metal. Ion exchange was performed by the method shown below.

(Ion exchange) Approximately 10 g of Na-type Y-type zeolite with an aqueous metal chloride solution (0.5 mo
About 100 g of /) was added and the mixture was allowed to stand at a temperature of 90 to 100 ° C for 2 hours. After repeating the above operation 3 times, after drying, the temperature is 400 ℃
It was baked for 3 hours.

The adsorption separation experiment was performed by the method shown below.

(Adsorption separation experiment) About 4 g of adsorbent, about 6.5 g of feed oil, and about 1.5 g of diethylbenzene as a desorbent were charged in an autoclave with an internal volume of 30 cc, and the temperature was kept constant while stirring and kept for 120 minutes. The adsorbent and the raw material residual liquid were separated by filtration, and the adsorbate in the adsorbent was desorbed by Soxhlet extraction using a toluene solvent after washing the adsorbent with isooctane. The compositions of the raw material residual liquid (liquid phase) and the adsorbate (adsorption phase) were analyzed by gas chromatography, and their relative separation coefficients were calculated. The results are shown in Table-3.

(III) Separation of 2,6-isomer Next, it is obtained by the distillation treatment and the vapor deposition separation treatment.
Isomeric mixture containing no 1,3-, 1,7- and 2,7-isomers
(1,5-isomer: 1.6 wt%, 1,4-isomer: 9.2 wt%, 1,6-isomer: 35.0 wt%, 2,3-isomer: 11.0 wt%, 2,6-isomer Body: 41.7
wt%, others: 1.5wt%) About 30g of n-heptane was added to 100g, cooled to 0 ° C to precipitate crystals, and then filtered, resulting in about 30g of crystals of 2,6-isomer with 98.1wt% purity. Obtained.

Example 2 The potassium-substituted Y-type zeolite shown in Example 1 was used as an adsorbent, and various desorbents shown in Table 4 were used as a raw material for 20 parts by weight of the diisopropylnaphthalene isomer mixture shown in Table 2. An adsorption separation experiment was conducted in the same manner as in Example 1 using the one to which parts by weight were added, and the β value was calculated. The results are shown in Table 4.

Example 3 The adsorption separation of 2,7-diisopropylnaphthalene from the raw materials shown in Table 2 of Example 1 was carried out using the simulated moving bed type continuous adsorption separation apparatus shown in FIG. In the separation operation,
Diethylbenzene was used as the potassium-substituted Y-type zeolite adsorbent and the desorbent shown in Example 1. The adsorbent was filled in the column adsorption chambers 1 to 16 having an internal volume of 70 m, the raw material was supplied from the line 19, the desorbent was supplied from the line 17, and the extract and the raffinate were extracted from the line 20. As shown in Table-5, the flow rate of each operation zone was changed by changing the feed amount of the raw material and the desorbent, the extract amount, and the raffinate withdrawal amount.

In addition, the feed lines for the raw material and the desorbent and the extraction lines for the extract and raffinate were moved simultaneously in the liquid flow direction by one adsorption chamber at regular time intervals.
At this time, the adsorbent flow rate (S) in each zone was 818 cc / hr.

Table 5 shows the purity and recovery of 2,7-diisopropylnaphthalene in the extract in each experiment.

In Experiment No. 2, since L (I) / S (I) was too small, the 2,7-isomer was circulated while being adsorbed by the adsorbent, and was mixed with the raffinate to lower the recovery rate.

In Experiment No. 3, since L (II) / S (II) was too small, isomers other than the 2,7-isomer were mixed in the extract and the purity was lowered.

In Experiment No. 4, since the L (III) / S (III) was too large, the 2,7-isomer was mixed in the raffinate and the recovery rate was lowered.

In Experiment No. 5, since L (IV) / S (IV) was too large, components other than the 2,7-isomer were mixed in the desorbent and circulated, and mixed in the extract, so that 2,7- The purity of the isomer decreases.

In Experiment No. 6, since L (IV) / S (IV) was too small, components other than the 2,7-isomer were mixed in the extract, and the purity of the 2,7-isomer was lowered.

Example 4 (I) Adsorption separation treatment An adsorption separation experiment was conducted in the same manner as in Example 1 using the diisopropylnaphthalene isomer mixture having the composition shown in Table 1 as a raw material and potassium-substituted Y-type zeolite. The relative separation coefficient was calculated. As a result, β (2,7
/ 1,3): 21.0, β (2,7 / 1,7): 0.8, β (2,7 / 1,5): 2.3,
β (2,7 / 1,4): 9.4, β (2,7 / 1,6): 10.3, β (2,7 / 2,3):
The relative separation factors of 5.4 and β (2,7 / 2,6): 19.3 were obtained.

As can be seen from the above results, 1,7-
It can be seen that the isomer is separated from other isomers as a strongly adsorbed component along with the 2,7-isomer. And, as can be seen from Table-1, the 1,7-isomer and the 2,7-isomer have a boiling point difference of 8 ° C., and therefore, they can be separated from each other by distillation.

Also, from the diisopropylnaphthalene mixture in Table-1, 2,7-
And the isomer mixture after separation of the 1,7-isomers in Example 1
As a result of the crystallization separation treatment in the same manner as in 2,
Similarly, the 6-isomer could be recovered with high purity by crystallization separation treatment.

Example 5 The desorbent was removed by distillation from the raffinate obtained in Experiment No. 1 of Example 3 to obtain a diisopropylnaphthalene mixture having the composition shown in Table-6. Separation of 2,6-diisopropylnaphthalene from the diisopropylnaphthalene mixture shown in Table 6 was carried out using the simulated moving bed continuous adsorption separation device shown in FIG. In the separation operation, Na-Y as the adsorbent
Diethylbenzene was used as the zeolite adsorbent and desorbent.

The adsorbent was packed in a column adsorption chamber 1-16 with an internal volume of 70 m,
The raw material was supplied from line 19 at 25 m / hr, and the desorbent was supplied from line 17 at 80 m / hr. The extract was extracted from line 18 at 70 m / hr, and the raffinate was extracted from line 20 at 35 m / hr.

At this time, the feed lines of the raw material and the desorbent and the extraction lines of the extract and the raffinate were simultaneously moved in the direction of liquid flow by one chamber of the adsorption chamber at intervals of 480 seconds. 2,6-Diisopropylnaphthalene was obtained from the extract, and its 2,6-diisopropylnaphthalene concentration was 99 wt% on a desorbent-free basis, and the recovery rate was 90 wt%.

Example 6 Diisopropylnaphthalene mixture having composition shown in Table 6
About 30 g of n-heptane was added to 100 g, and the mixture was cooled to 0 ° C. to precipitate crystals, which was filtered to obtain about 25 g of 2,6-isomer crystals having a purity of 97.9 wt%.

Example 7 Diisopropylnaphthalene mixture whose composition is shown in Table-6.
Add 74.3 g of methanol and 18.9 g of thiourea to 3 g and add 60 ° C.
It was kept for 30 minutes with stirring. Then, the mixture was gradually cooled to room temperature, cooled to -5 ° C, and kept for about 18 hours. The precipitated urea adduct was filtered and washed with methyl ether, and the adduct was decomposed with distilled water.

Benzene was added to this decomposed solution, and benzene was extracted. The purity of 2,6-diisopropylnaphthalene separated and recovered on the extract side calculated from the composition and amount of the extract, filtrate, and washing solution was 95.3 wt%, and the recovery rate was 81.6 wt%.

[Brief description of drawings]

FIG. 1 is a schematic diagram of an adsorption separation device using a simulated moving bed. FIG. 2 shows a flow sheet of the first process of the present invention in which the distillation process and the adsorption separation process are combined in that order. FIG. 3 shows a flow sheet of the second process of the present invention in which the adsorption separation treatment and the distillation treatment are combined in order. 1 to 16 ... Adsorption chamber, 17 ... Desorbent supply line, 18 ... Extract extraction line, 19 ... Raw material mixture supply line, 20 ... Raffinate extraction line, 21 ... Recycle line, 22 ... Recycle Pump, 31 ... Distillation tower, 32 ...
… Adsorption separation device, 38 …… 2,6-isomer separation device.

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Kenji Shimokawa 89 Mitsukyo, Seya-ku, Yokohama-shi, Kanagawa Prefecture (72) Inventor Yoshio Fukui 4-5-503 Ichibancho, Chiyoda-ku, Tokyo (72) Inventor Tachibana Dynamic Tokyo Chiyoda-ku, Marunouchi 1-2-2 Nihon Steel Pipe Co., Ltd. (72) Inventor Kazuhiko Tate Marunouchi, Chiyoda-ku, Tokyo Marunouchi 1-2-2 Nihon Steel Pipe Co., Ltd. (72) Inventor Hiroaki Taniguchi Chiyoda-ku, Tokyo Marunouchi 1-2, Nihon Steel Pipe Co., Ltd.

Claims (5)

[Claims] 1. When separating 2,7- and 2,6-diisopropylnaphthalene from a diisopropylnaphthalene isomer mixture, the mixture is subjected to a distillation treatment to separate 1,7- and 1,3-isomers. 1 step and 1,7- and 1 obtained in the first step
Diisopropylnaphthalene isomer mixture containing no 1,3-isomer is subjected to adsorption separation treatment using a zeolite adsorbent and a desorbent exhibiting selective adsorption to the 2,7-isomer to give the 2,7-isomer. An extract containing the same, a second step for obtaining a raffinate containing the 2,6-isomer, and a third step for separating the 2,6-isomer contained therein from the raffinate 2,7 -And 2,6-diisopropylnaphthalene separation method. 2. A zeolite adsorbent which exhibits selective adsorption to 2,7- and 1,7-isomers when separating 2,7- and 2,6-diisopropylnaphthalene from a diisopropylnaphthalene isomer mixture. And an adsorption-separation treatment using a desorbent to obtain an extract containing 2,7- and 1,7-isomers and 2,6-
The first step for obtaining a raffinate containing an isomer and the extract obtained in the first step are subjected to a distillation treatment to separate the 2,7-isomer and the 1,7-isomer, 2,7- and 2,6 characterized by comprising a second step for obtaining an isomer and a third step for separating the 2,6-isomer contained therein from the raffinate obtained in the first step -A method for separating diisopropylnaphthalene. 3. The method according to claim 1 or 2, wherein the adsorbent used in the adsorption separation treatment is potassium-substituted Y-type zeolite. 4. The method according to claim 1, wherein the desorbent used in the adsorption separation treatment is an alkylbenzene derivative represented by the following general formula. (In the formula, R and R ′ are a methyl group, an ethyl group, an n-propyl group or an isopropyl group, and n is 0 or 1.) 5. A desorption operation using a countercurrent type simulated moving bed having a plurality of adsorption chambers filled with an adsorbent for adsorption separation treatment.
5. The method according to any one of claims 1 to 4, wherein four operations including a concentration operation, an adsorption operation and a desorbent recovery operation are simultaneously and successively performed, and each operation zone is performed under the conditions shown below. (i) Desorption operation zone L (I) / S (I)> 0.2 + L (IV) / S (I) (where L (I) is the liquid flow rate (cc / hr) in the desorption operation zone, S
(I) is the adsorbent flow rate (cc / hr) and L moving in the desorption operation zone.
(IV) indicates the liquid flow rate (cc / hr) flowing through the desorbent recovery zone. (Ii) Concentration operation zone L (II) / S (II)> 0.1 + L (IV) / S (II) (in the formula) , L (II) is the liquid flow rate (cc / hr) flowing through the concentration operation zone,
S (II) is the adsorbent flow rate (cc / hr) moving in the concentration operation zone and
L (IV) indicates the liquid flow rate (cc / hr) flowing through the desorbent recovery zone) (iii) Adsorption operation zone L (III) / S (III) <0.3 + L (IV) / S (III) (equation Where L (III) is the liquid flow rate (cc / h
r) and S (III) are the adsorbent flow rate (cc / h
r) and L (IV) are liquid flow rates (cc / hr) flowing through the desorbent recovery zone) (iv) Desorbent recovery operation zone 0.8 <L (IV) / S (IV) <1.0 (wherein L (IV) is the liquid flow rate (cc
/ hr) and S (IV) are the adsorbent flow rates (cc / hr) moving in the desorbent recovery operation zone.