JPH0967275A - Separation of monoisopropylbiphenyl isomer - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain 3-isopropylbiphenyl and 4-isopropylbiphenyl in high purities, useful for the raw materials of resins, a dyestuffs, etc., by adsorbing and separating them from their mixture using a zeolite as an adsorbent. SOLUTION: These 3-isopropylbiphenyl and 4-isopropylbiphenyl are obtained by contacting a solution containing their mixture with a zeolite, and adsorbing and separating both of them. Concretely, it is preferable that a strongly adsorbable 3-isopropylbiphenyl is selectively adsorbed by contacting the mixture with the zeolite, and also, a weakly adsorbable 4-isopropylbiphenyl is recovered as a raffinate, and then the adsorbed 3-isopropylbiphenyl is desorbed by a desorbing agent and recovered. As the zeolite, an X-type or a Y-type zeolite containing K<+> is preferable. These are preferably formed as a spherical or a noodle shape. Also, as a particle size, 0.1-0.7mm specific surface area diameter is preferable. As the desorbent, toluene, xylene, etc., are preferable.

Description

Detailed Description of the Invention

[0001]

TECHNICAL FIELD The present invention relates to a method for separating 3-isopropylbiphenyl and 4-isopropylbiphenyl, and more particularly to 3-isopropylbiphenyl and 4-isopropylbiphenyl.
-A solution containing a mixture with isopropyl biphenyl is brought into contact with the zeolite, and the high purity 3 is obtained by adsorption separation.
-A method for obtaining isopropyl biphenyl or 4-isopropyl biphenyl.

[0002]

2. Description of the Related Art 3- and 4-Isopropylbiphenyl used as various chemical raw materials are required to have high purity for their use. Therefore, it is desirable to produce high purity 3- and 4-isopropyl biphenyl of 98% or more. Three or four such high-purity isopropyl biphenyls are industrially very useful, and pure 3-isopropyl biphenyl or pure 4-isopropyl biphenyl is 3-phenylphenol or 4-phenyl, respectively.
It is used as a raw material for phenylphenol and the like in liquid crystals, resins, antioxidants and the like.

The monoisopropylbiphenyl which is a raw material of the present invention is usually obtained by distilling a monoisopropylbiphenyl fraction from an isopropylated biphenyl mixture obtained by isopropylating or transisopropylating biphenyl. The fraction is a mixture of 3- and 4-isopropylbiphenyl. The composition ratio of the 3- and 4-isomers can be changed largely depending on the alkylation catalyst and reaction conditions, but it is not possible to synthesize only one of them.

As a method for producing high-purity 3-isopropylbiphenyl and 4-isopropylbiphenyl by separating and purifying this monoisopropylbiphenyl fraction, first, separation by distillation is known. Since the boiling points of 4-isopropylbiphenyl and 4-isopropylbiphenyl are close to 296 ° C and 303 ° C, respectively, a large number of stages and a high reflux ratio are required for separation / purification by industrial distillation, which is costly and economically undesirable. .

A method is known in which 3-isopropylbiphenyl and 4-isopropylbiphenyl are separated by a crystallization method utilizing the difference in melting point between 3-isopropylbiphenyl and 4-isopropylbiphenyl. However, although 4-isopropylbiphenyl having a high melting point can be recovered by a crystallization method, it is difficult to recover 4-isopropylbiphenyl remaining in the filtrate, and 3-isopropylbiphenyl having a low melting point can be recovered at a high concentration. It is difficult to efficiently recover with purity.

Regarding the method for separating alkyl aromatic compound isomers, in JP-A-6-219972, a mixture of α-monoisopropylnaphthalene and β-monoisopropylnaphthalene is brought into contact with zeolite to separate non-adsorbed substances. There is an example in which a mutual separation method of α- and β-monoisopropylnaphthalene is disclosed.

[0007]

However, each of the above-mentioned methods by distillation has a large energy cost for operation and is not suitable for a continuous process of mass production type. Further, a decisive drawback of these crystallization techniques is that although high-purity 4-isopropylbiphenyl can be produced at the cost of cost, the purification of 3-isopropylbiphenyl, which is a low-melting isomer, to high-purity Was almost impossible. Further, until now, no attempt has been made to adsorb and separate 3-isopropyl biphenyl and 4-isopropyl biphenyl.

Accordingly, an object of the present invention is to provide a method for adsorbing and separating 3-isopropylbiphenyl and 4-isopropylbiphenyl to obtain high-purity 3-isopropylbiphenyl or 4-isopropylbiphenyl. .

[0009]

The present inventor has conducted extensive studies to solve the above-mentioned problems of the prior art. As a result, the following findings were obtained. That is, by utilizing the difference in the adsorption force between 3-isopropylbiphenyl and 4-isopropylbiphenyl with respect to a specific adsorbent,
It has been found that isopropyl biphenyl or 4-isopropyl biphenyl can be selectively separated.

The present invention has been made on the basis of the above findings. The method of the present invention comprises contacting a zeolite with a solution containing a mixture of 3-isopropylbiphenyl and 4-isopropylbiphenyl to give 3-isopropylbiphenyl. And 4-isopropylbiphenyl are adsorbed and separated.

Further, in the above method, X-type zeolite or Y-type zeolite containing a potassium cation is used as the zeolite.

Further, in any one of the above methods, the mixture of 3-isopropylbiphenyl and 4-isopropylbiphenyl is supplied from one end of the adsorption tower, the mixture is adsorbed and separated in the adsorption tower, and An adsorption separation step of recovering substantially pure 3-isopropylbiphenyl or pure 4-isopropylbiphenyl from the other end of the adsorption tower, using a substitution liquid, remaining in the adsorption tower 3
-A substitution step of removing and recovering the mixture of isopropylbiphenyl and 4-isopropylbiphenyl, and
High-purity 3-isopropylbiphenyl or 4-isopropylbiphenyl is recovered as a target by a simulated moving bed continuous adsorption separation process comprising a recovery step for recovering the substitution liquid.

[0013]

BEST MODE FOR CARRYING OUT THE INVENTION The present invention relates to a method for adsorbing and separating 3-isopropylbiphenyl and 4-isopropylbiphenyl to obtain high-purity 3-isopropylbiphenyl or 4-isopropylbiphenyl. In the method of the present invention, a mixture of 3-isopropylbiphenyl and 4-isopropylbiphenyl is brought into contact with zeolite as an adsorbent to give a strongly adsorbed component 3
-Isopropylbiphenyl is selectively adsorbed on the adsorbent, then 4-isopropylbiphenyl, which is a weakly adsorbed component, is recovered as a raffinate, and then 3-isopropyl adsorbed on the adsorbent by the desorbent. The biphenyl is released and 3-isopropylbiphenyl is recovered.

The mixture containing 3-isopropylbiphenyl and 4-isopropylbiphenyl as a raw material can be obtained by isopropylating biphenyl. However, the mixture as a raw material should just contain 3-isopropyl biphenyl and 4-isopropyl biphenyl, and is not limited to the mixture of 3-isopropyl biphenyl and 4-isopropyl biphenyl.

It is desirable that both the X-type zeolite and the Y-type zeolite as the adsorbent are industrially molded into spherical or noodle shapes before use. The adsorbent formed into a spherical shape or noodle shape needs to have appropriate mechanical strength and powder resistance. Therefore, it is usually 20 wt.
A binder such as alumina or clay of less than wt.% is often added. However, if mechanical strength and pulverization resistance can be secured, the molding may be performed without adding a binder.

The particle size of the adsorbent is generally such that the smaller the adsorbent is, the faster it adsorbs the substance to be separated, and
It is desirable because the speed of desorption is high. On the other hand, if it becomes too small, the fluid pressure loss of the layer filled with the adsorbent increases.
Therefore, the particle size of the adsorbent is industrially suitable to have a specific surface area diameter of 1.5 mm or less, and preferably 0.7 mm or less. On the other hand, the lower limit of the specific surface area diameter is 0.05 mm
It is above, and 0.1 mm or more is desirable.

Of the zeolite used in the present invention,
The separation coefficient α obtained by the following equation is 1.5 or more. That is,

[Equation 1] Then, the separation coefficient α is expressed by the following equation.

[Equation 2] Therefore,

## _EQU3 ## α = (C _1E / C _1R ) / (C _2E / C _2R ) where C _1E : concentration of 3-isopropyl biphenyl in extract C _1R : concentration of 3-isopropyl biphenyl in raffinate C _2E : extra Concentration of 4-isopropylbiphenyl in the emulsion C _2R : Concentration of 4-isopropylbiphenyl in the raffinate

When zeolite having a separation coefficient α of 1.5 or more is used, it can be practically used, but it is more advantageous to use a zeolite having a large separation coefficient. From the viewpoint of equipment, zeolite having a separation factor of 2 or more is preferable.
When the mixture of 3-isopropyl biphenyl and 4-isopropyl biphenyl contains a solvent, the separation coefficient varies depending on the type of solvent.

When the liquid phase and the solid phase are in equilibrium,
The separation factor α can be regarded as the same as the theoretical measure of the degree of separation obtained at each stage of adsorption. By redistributing each component either in the liquid phase or in the solid phase from one adsorption stage to another, the mixture is distributed to each phase in a ratio determined by the separation factor α.

This process can essentially be repeated until 100% separation of the components is obtained. Therefore, knowing the separation factor of a given feed mixture, the number of theoretical steps required for the required degree of separation can be easily calculated.

The desorbent used in the present invention may be any substance having an adsorbing power capable of desorbing the components of the raw materials adsorbed by the adsorbent from the adsorbent, but 3-isopropylbiphenyl and 4-isopropyl A substance having a large difference in boiling point from that of biphenyl is desirable.

Such desorbents include benzene, various alkylbenzenes and tetralin. For example, toluene, xylene, ethylbenzene, diethylbenzene, cumene, cymene, etc. are used. Toluene, xylene and diethylbenzene are preferable.

It is desirable that such a desorbing agent is a single substance in order to simplify the whole process, but by mixing substances having different adsorption powers in an appropriate ratio, a desorbing agent satisfying the above conditions can be obtained. It is also possible to do so.

The adsorptive separation according to the present invention may be carried out by either a batch system or a continuous system. In the process of separating and purifying 3-isopropylbiphenyl and 4-isopropylbiphenyl by the batch method, generally, 3-isopropylbiphenyl having a stronger adsorptive power is adsorbed.

As a process for carrying out the method of the present invention, for example, a simulated moving bed continuous adsorption separation process (Japanese Patent Publication No. 42-15681) which is industrially carried out for separating pure p-xylene from mixed xylenes. Gazette) is appropriate.

That is, a desorbent having an adsorptive power capable of desorbing the components of the raw material adsorbed by the adsorbent from the adsorbent is selected, and an adsorption tower composed of two or more zeolites is packed into each adsorbent. A process of continuously separating as a whole can be applied while intermittently operating in the adsorption tower. According to this process, the operating conditions are different between the case of producing high-purity 3-isopropylbiphenyl and the case of producing high-purity 4-isopropylbiphenyl. The operation for the purpose of producing 4-isopropylbiphenyl can be carried out substantially as a continuous process by repeating the cycle consisting of the following steps and shifting the operation cycle of a plurality of adsorption towers. A raw material (a mixture of 3-isopropylbiphenyl and 4-isopropylbiphenyl) is supplied from one end of the adsorption tower to selectively adsorb 3-isopropylbiphenyl, and substantially 3-isopropylbiphenyl from the other end of the adsorption tower. Adsorption separation step to recover pure 4-isopropylbiphenyl that does not contain, the supply of raw materials is interrupted immediately before the adsorbent breaks through with 3-isopropylbiphenyl, and the supply liquid is switched to the replacement liquid to remain in the adsorption tower. By a substitution step of removing and recovering a mixture of 3-isopropylbiphenyl and 4-isopropylbiphenyl, and heating or / and depressurizing the adsorption tower,
A recovery step of recovering the replacement liquid.

The present invention is not limited to the above-mentioned method, but it is possible to use a batch process using one adsorption tower.

FIG. 1 is a block diagram showing an outline of an apparatus used in one embodiment of the present invention. In FIG. 1, 1 to 16 are columns, 17 is a desorbent supply line, 1
8 is an extract line, 19 is a mixture supply line of 3-isopropyl biphenyl and 4-isopropyl biphenyl, 20 is a raffinate line, 21 is a circulation line, and 22 is a circulation pump.

[0029]

【Example】

Example 1 A commercially available KY type zeolite (SiO ₂ / Al ₂ ) was used as an adsorbent in an Erlenmeyer flask with an internal volume of 50 ml equipped with a stopper.
O ₃ = 5, particle size: 40-80 mesh dried and baked at 350 ° C. for 2 hours) 4 parts by weight, 3-isopropylbiphenyl /
1.64 parts by weight of a raw material mixture of 4-isopropylbiphenyl = 61/39, 6 parts by weight of diethylbenzene as a desorbent, and a non-adsorbed component as an internal standard substance 1,
0.36 parts by weight of 3,5-triisopropylbenzene was added, and the mixture was heated and shaken at a temperature of 140 ° C. for 4 hours to reach equilibrium. Next, after separating the liquid phase (raffinate) and the solid phase (extract), the liquid phase composition is analyzed using a gas chromatograph, and the weight of each component in the liquid phase is calculated. It was calculated by subtracting the weight of each compositional component in the liquid phase from the weight of each component. From the composition of these liquid phase and solid phase, the separation coefficient of 4-isopropylbiphenyl based on 3-isopropylbiphenyl was 2.17.

Example 2 Instead of KY type zeolite as an adsorbent, KX type zeolite (SiO ₂ / Al ₂ O ₃ = 2.
5. Particle size: 40-80 mesh was dried and calcined at 350 ° C. for 2 hours, and the equilibrium test was carried out in exactly the same manner as in Example 1. 4 based on 3-isopropylbiphenyl
The separation factor of isopropyl biphenyl is shown in Table 1.

[0031]

[Table 1]

Example 3 The same equilibrium test as in Example 1 was carried out except that p-xylene was used as the desorbent.
Table 1 shows the separation factor of 4-isopropylbiphenyl based on 3-isopropylbiphenyl.

Example 4 An equilibrium test was carried out in exactly the same manner as in Example 1 except that tetralin was used as the desorbent. 3
Table 1 shows the separation factor of 4-isopropylbiphenyl based on isopropylbiphenyl.

Comparative Examples 1 to 4 The same equilibrium test as in Example 1 was carried out except that the zeolite shown in Table 1 was used as the adsorbent. Table 1 shows the separation factor of 4-isopropylbiphenyl based on 3-isopropylbiphenyl.

Example 5 In an Erlenmeyer flask with an internal volume of 50 ml equipped with a stopper, a commercially available KY type zeolite (SiO ₂ / Al ₂ O ₃ = 5, particle size: 40-80 mesh) was used as an adsorbent.
(Drying and baking at 2 ° C. for 2 hours) 10 parts by weight, 3-isopropylbiphenyl / 4-isopropylbiphenyl = 61/39
1.25 parts by weight of the starting material mixture and 23.75 parts by weight of diethylbenzene as a desorbing agent were added, and the mixture was heated and shaken at a temperature of 140 ° C. for 4 hours to reach equilibrium. Next, filtration,
After the liquid phase (raffinate) and the solid phase (extract) were separated by washing and extraction, the composition of each was analyzed using a gas chromatograph, and the separation factor of 4-isopropylbiphenyl based on 3-isopropylbiphenyl was determined. Was calculated. The separation factor was 2.17.

[Examples 6 to 9] Separation coefficients were measured by the same equipment and method as in Example 5 under the condition that the raw material / desorbent (diethylbenzene) ratio was different. The results are shown in Table 2.

[0037]

[Table 2]

[Examples 10 to 15] Example 5 was carried out using a vacuum precision distillation column and using a raw material concentrated to 3-isopropylbiphenyl / 4-isopropylbiphenyl = 15/85.
Separation coefficient was measured under the condition that the ratio of raw material / desorbent (diethylbenzene) was different by the same equipment and method. The results are shown in Table 2.

Example 15 The adsorption separation of 3-isopropylbiphenyl and 4-isopropylbiphenyl was carried out using the simulated moving bed type continuous adsorption separation device shown in FIG.
3-isopropylbiphenyl / 4-isopropylbiphenyl = 61/39 was used as a raw material, and the KY type zeolite shown in Example 1 was used as an adsorbent in a packed volume of 7
It was packed in 0 ml of columns 1 to 16 and diethylbenzene was used as a desorbent. The raw material mixed isopropyl biphenyl was supplied from line 19 at 60 ml / Hr, and the desorbent was supplied from line 17 at 550 ml / Hr. On the other hand, the extract was extracted from line 18 at 500 ml / Hr, and the raffinate was extracted from line 20 at 110 ml / Hr. In addition, the switching of each supply line and the withdrawal line (each line is simultaneously moved by one column in the liquid flow direction) was performed at 127 second intervals. 4-Isopropylbiphenyl was obtained from raffinate with a purity of 98.8% desorbent free base and a recovery of 80%.

Example 16 Using a vacuum precision distillation column, 3
Adsorption separation of 3-isopropylbiphenyl and 4-isopropylbiphenyl was carried out by using the same material and method as in Example 15 using the raw material concentrated to -isopropylbiphenyl / 4-isopropylbiphenyl = 70/30. The mixed isopropyl biphenyl of the raw material is 60 ml / Hr from the line 19, and the desorbent is 51 from the line 17.
It was supplied at 5 ml / Hr. On the other hand, the extract was extracted from line 18 at 360 ml / Hr, and the raffinate was extracted from line 20 at 215 ml / Hr. In addition, switching between each supply line and extraction line (moving each line in the direction of liquid flow for one column at the same time) is 1
It was performed at 27 second intervals. 3-Isopropylbiphenyl was obtained from the extract, and its purity was 99.0% on a desorbent-free basis, and the recovery rate was 89%.

From these results, it can be said that it is sufficiently possible to carry out this separation process as a simulated moving bed type continuous adsorption separation process.

[0042]

According to the method of the present invention, highly pure 3-isopropylbiphenyl and 4-isopropylbiphenyl, which are extremely useful as raw materials for resins, dyes, pharmaceuticals, etc., can be produced. Further, when the present invention is applied to a simulated moving bed type continuous adsorption process, it becomes a process capable of processing a larger amount, and its industrial significance is extremely large.

[Brief description of drawings]

1 shows one of the embodiments of the method according to the invention.

[Explanation of symbols]

 1 to 16 column 17 desorbent supply line 18 extract line 19 mixed isopropyl biphenyl supply line 20 raffinate line 21 circulation line 22 circulation pump

Claims (2)

[Claims] 1. Monoisopropylbiphenyl, characterized in that a solution containing a mixture of 3-isopropylbiphenyl and 4-isopropylbiphenyl is brought into contact with zeolite to adsorb and separate 3-isopropylbiphenyl and 4-isopropylbiphenyl. Method for separating isomers. 2. The method for separating monoisopropylbiphenyl isomers according to claim 1, wherein an X-type zeolite or a Y-type zeolite containing a potassium cation is used as the zeolite.