JP2683762B2 - Method for producing bisphenol A / phenol crystal adduct having good hue - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for producing a bisphenol A / phenol crystal adduct having a good hue.

[0002]

BACKGROUND OF THE INVENTION Bisphenol A [2.2
-Bis (4'-hydroxyphenyl) propane] is known to react acetone with excess phenol in the presence of an acid catalyst. In order to separate and recover high-purity bisphenol A from this reaction product, the reaction product is cooled to precipitate a crystal adduct of bisphenol A and phenol (hereinafter, also simply referred to as a crystal adduct), and the obtained adduct is obtained. It is also known to remove phenol from crystals. In such a method for producing bisphenol A, the purity and the hue of bisphenol A recovered as a product largely depend on the purity and the hue of the crystal adduct, and a method for producing a crystal adduct with high purity and good hue is required. . In order to obtain a high-purity crystal adduct from a phenol solution containing bisphenol A obtained by reacting excess phenol with acetone, the phenol solution is subjected to a crystallization step of a plurality of stages, a crystal adduct separation step and a dissolution step. It is known to process by a series of crystallization steps linked via a. In the conventional method for producing a crystal adduct using a plurality of crystallization steps, one crystallization tower is used in each crystallization step, and the number of crystallization steps should be increased. It is possible to obtain a crystal adduct of higher purity. However, in this case, if the number of stages of the crystallization process is increased, it is necessary to increase the number of crystal adduct separation devices and crystal adduct dissolution tanks in accordance with the increase in the number of crystallization process stages. In addition, there is a problem that the size becomes large and the device cost becomes high.

[0003]

SUMMARY OF THE INVENTION The present invention provides a method for miniaturizing a crystallizer system for obtaining a crystal adduct and efficiently producing a crystal adduct of high purity and good hue. That is the subject.

[0004]

Means for Solving the Problems The present inventors have conducted intensive studies to solve the above-mentioned problems, and as a result, have completed the present invention. That is, according to the present invention, the phenol solution in which bisphenol A is dissolved is supplied to the first crystallization tower (A) of the two crystallization towers connected in series for performing the first crystallization step. , A bisphenol A / phenol crystal adduct having a particle size of 100 μm or less and a microcrystalline component content of 3
Coarse seed crystals of 0 wt% or less are precipitated, and the crystallization product containing the seed crystals obtained in this crystallization step is introduced into the second crystallization tower (B), and the first crystallization tower (A ) The crystal growth of the seed crystal is performed at a lower temperature to produce a coarse crystal adduct having a grain size of 100 μm or less and a fine crystal component content of 30% by weight or less, and then obtained in the first crystallization step. The crystallized product is introduced into the solid-liquid separation step to separate the crystal adduct from the mother liquor, and the crystal adduct is redissolved in phenol having a higher purity than the mother liquor, followed by the second crystallization step. Is supplied to the first crystallization tower (C) of the two crystallization towers connected in series, and the content of the fine crystal component of the bisphenol A / phenol crystal adduct having a particle size of 100 μm or less is 30% by weight or less. While precipitating coarse seed crystals of
The crystallization product containing the crystal adduct obtained in this crystallization step is introduced into the second crystallization tower (D), and the seed crystal is grown at a temperature lower than that of the first crystallization tower (C). Particle size 100μ
Provided is a method for producing a bisphenol A / phenol crystal adduct having a good hue, which is characterized in that a coarse crystal adduct having a fine crystal component content of m or less is 30% by weight or less.

Next, the present invention will be described with reference to the drawings. FIG. 1 shows a system diagram of an apparatus for carrying out the present invention. In this figure, A, B, C and D represent crystallization towers, E represents a solid-liquid separator, and F represents a dissolution tank. Inside each of the crystallization towers A, B, C and D, an inner cylinder P having an opening at the top is inserted and arranged. Further, a microcrystal adduct dissolution tank Q is attached to each of the crystallization towers A, B, C and D. Crystallizer A and B
Are connected in series to form an apparatus system for performing the first-stage crystallization step, and the crystallization towers C and D are connected in series to form a second
An apparatus system for performing the step crystallization process is configured. A phenol solution containing bisphenol A as a raw material to be treated is supplied to the lower part of the first crystallization tower A of the two crystallization towers A and B connected in series through line 1 and line 2,
Here, seed crystals composed of bisphenol A / phenol crystal adduct are deposited. In the crystallization tower A, the phenol solution containing the crystal adduct (seed crystal) at the upper part of the tower flows down in the inner cylinder P, is extracted to the outside through the line 3, and is pumped by the pump 4, the line 5 and the cooling. It is circulated in the first crystallization tower A through the vessel 6 and the line 2, whereby the phenol solution in the crystallization tower A is cooled and the crystallization tower A is cooled to a predetermined temperature. A part of the crystallization product containing seed crystals extracted from the inner cylinder P in the crystallization tower A (hereinafter, also simply referred to as slurry) is part of a line 7, a pump 8, a line 9, a line 10 and a heater 11. Is introduced into a fine crystal adduct dissolution tank Q through which the fine crystals in the crystal adduct are dissolved, and a slurry containing only seed crystals of coarse crystals of a certain size is passed through line 13 to the crystallization tower A. Of the seed crystals contained in the crystallization tower A are made uniform,
In the crystallization tower A, seed crystals having a low content of fine crystals and a high content of coarse crystals are generated. The microcrystalline adduct in the crystallization tower A has a large specific surface area and exhibits a high adsorbability for a coloring-causing substance (a substance causing a deterioration in hue). Therefore, by reducing the content of the fine crystal component particles in the crystal adduct obtained as a seed crystal in the crystallization tower A as much as possible, a seed crystal with a good hue can be obtained. According to the research conducted by the present inventors, the grain size in the crystal adduct is 100 μm.
It has been found that a high-purity coarse crystal adduct having a good hue can be produced by maintaining the particle content of the following fine crystal component at 30% by weight or less, preferably 20% by weight or less.

The phenol solution containing bisphenol A used as a raw material to be treated in the present invention usually contains bisphenol A: 7 to 50% by weight, preferably 10 to 30% by weight. Body, trisphenol, etc. in a proportion of 8% by weight or less.
The temperature of the phenol solution containing bisphenol A supplied from the line 1 is 1-2 from the saturation temperature of the crystal adduct.
It is a high temperature of about 0 ° C. The crystallization temperature of the crystallization tower A is 45 to
The temperature is 70 ° C, preferably 48 to 57 ° C. The temperature of the slurry circulated through the line 3, the pump 4, the cooler 6 and the line 2 is lowered in the cooler 6 by about 10 ° C. or less, preferably about 5 ° C. or less. The residence time of the phenol solution in the crystallization tower A is 0.5 to 10 hours,
It is preferably 0.5 to 5 hours. On the other hand, the slurry introduced into the microcrystalline adduct dissolution tank Q through the line 7, the pump 8, the line 10 and the heater 11 is the heater 1
In No. 1, the temperature is increased by 0.5 to 5 ° C.
The retention time of the phenol solution in this tank Q is 3 to
It takes about 15 minutes. In the microcrystal dissolution tank Q,
Mainly, crystallite adducts with a particle size of 100 μm or less are dissolved,
The slurry in which the crystallite adduct is dissolved is line 1
It is returned to the crystallization tower A through 3 and the crystal growth is promoted in the crystallization tower A to obtain a seed crystal of a coarse crystal.

Part of the slurry withdrawn from the bottom of the inner cylinder P in the first crystallization tower A is line 7, pump 8, line 1.
It is introduced into the lower part of the second crystallization tower B through 2 and the line 21, and the crystal adduct is grown there. This second
Crystallizer B is operated in the same manner as shown for Crystallizer A above. In the crystallization tower B, the temperature range is 45 to 7
The temperature is 0 ° C., and is kept about 3 to 10 ° C. lower than the crystallization temperature of the crystallization tower A. The temperature of the slurry passing through the cooler 26 is lowered by about 10 ° C. or less, preferably about 5 ° C. or less. On the other hand, the temperature of the slurry passing through the heater 31 is raised here by about 0.5 to 5 ° C. In the microcrystal adduct dissolution tank Q attached to the crystallization tower B,
The crystal adduct component having a particle size of 100 μm or less is dissolved, and the slurry in which the fine crystal adduct is dissolved is returned to the crystallization tower through the line 33 to promote the growth of the crystal. The concentration of the crystal adduct in the slurry extracted from the bottom of the inner cylinder P in the crystallization tower B is 35% by weight or less, preferably 25% by weight or less, and the particle size in the crystal adduct is 100 μm.
The particle content of the following microcrystalline component is 30% by weight or less, preferably 20% by weight or less.

A part of the slurry withdrawn from the bottom of the inner cylinder P in the second crystallization tower B is introduced into the solid-liquid separator E through a line 35, where the crystal adduct and the mother liquor are separated. The separated and separated crystal adduct is introduced into the crystal adduct dissolution tank F through the line 36, and is again melted therein.
As the solid-liquid separation device E, a conventionally known device such as a centrifuge or a filtration device is used. As the dissolution tank E, a conventionally known one, for example, a stirring tank having a stirrer therein or a heating type dissolution tank is used. In the dissolution tank F, it is preferable to introduce purified phenol from the line 81 and use this purified phenol to dilute and dissolve the crystal adduct under stirring. In this case, heating may be used in combination, if necessary. The temperature of the melting tank is 70 to 160.
C., preferably 80 to 100.degree. As the purified phenol, one having a higher purity than that of the mother liquor is used.

When the crystalline adduct is diluted and dissolved with purified phenol, any purified phenol may be used so long as it does not cause the coloring of the product bisphenol A and has a low impurity content. Examples of the purified phenol that can be preferably used in the present invention include (i) a reaction product of phenol and acetone or a separated phenol, (ii) a phenol separated from a crystallization product of a phenol containing bisphenol, (Ii
A purified product of at least one phenol selected from i) used phenol after washing the crystal adduct and (iv) industrial phenol is used. The reaction product obtained by the reaction of phenol and acetone is separated from the reaction product in order to concentrate the produced bisphenol A contained therein, but in the present invention, the purified product of this phenol is used as a washing liquid. Can be used. In the case of crystallizing a phenol solution containing bisphenol A to precipitate a crystal adduct, a plurality of stages of crystallization and a solid-liquid separation step of a crystallization product are usually adopted, and a plurality of kinds of mother liquor are accordingly prepared. (Phenol solution)
However, in the present invention, the purified product of phenol forming these mother liquors can be used as a washing liquid. The purified phenol product used in the present invention may be a purified product of phenol forming any mother liquor of those mother liquors, but preferably phenol forming a mother liquor separated from the crystallization product obtained in the final crystallization step. It is preferable to use the purified product of. In the present invention, the used phenol is obtained after washing the crystal adduct, but in the present invention, the purified product of the used phenol can be advantageously used as the washing liquid. The raw material phenol used to obtain the purified phenol product according to the present invention has a purity of 9
It is preferable to use 5 wt% or more, preferably 97 wt% or more. Further, in the present invention, a purified product of industrial phenol can be used as a cleaning liquid. In this case, as the industrial phenol, phenol having a phenol purity of 95% by weight or more, preferably 97% by weight or more is used. Next, the method for obtaining purified phenol from the phenol will be described in detail. First, the phenol is contacted with a strong acid ion exchange resin to be treated. As the strong acid type ion exchange resin, one having a sulfone group is used, and such a strong acid type ion exchange resin is conventionally well known. For example, amberlite and amberlyst available from Rohm and Haas Co., or Kell type ones such as Diaion available from Mitsubishi Kasei can be preferably used. The treatment of phenol with this strong acid ion exchange resin is carried out by a method of circulating phenol in a packed column containing a strong acid ion exchange resin, a method of putting phenol in a stirring tank containing a strong acid ion exchange resin, and stirring it. It can be carried out. Treatment temperature is 45 ~
The temperature is 150 ° C, preferably 50 to 100 ° C. The contact time between the strong acid type ion exchange resin and phenol is 5 to 200.
Minutes, preferably about 15 to 60 minutes. When the phenol is treated using this strong acid type ion exchange resin, the water content in the phenol is 0.5% by weight or less, preferably 0.1% by weight or less. If there is more water than this,
The effect of removing impurities by the strong acid type ion exchange resin deteriorates. Removal of water up to 0.5% by weight or less from the phenol can be carried out by adding a known azeotropic agent to the phenol to cause azeotropic distillation. Phenol, which has been subjected to the contact treatment with the strong acid ion exchange resin, contains high-boiling-point impurities, and the high-boiling-point impurities are separated as a distillation residue by performing a distillation process. The operating conditions of the distillation column should be such that phenol and high-boiling impurities can be separated, but it is necessary to carry out under conditions where high-boiling impurities are not mixed in the distilled phenol.
It is to do the following. The operating pressure is arbitrarily set at a temperature of 200 ° C. or lower, but usually 50 Torr to 76
It is carried out under reduced pressure of 0 Torr or normal pressure. When the operating temperature exceeds 200 ° C., high-boiling impurities and the like are decomposed to deteriorate the quality of the purified phenol, which is not preferable. The purified phenol obtained by the above treatment has an APHA standard hue of 10 or less, and even if it adheres to the crystal adduct and the product bisphenol A, the hue is not particularly deteriorated.

The phenol solution containing bisphenol A from the dissolution tank F is introduced into the lower part of the first crystallization tower C which constitutes the crystallization system of the second stage through the line 41. in this case,
The phenol solution has a bisphenol A concentration of 7 to 50.
The concentration is adjusted to be 10% by weight, preferably 10 to 30% by weight. This crystallization tower C is operated in the same manner as that shown in the above crystallization tower A. In the crystallization tower C, the crystallization temperature is 45 to 70 ° C., which is 0 than the temperature of the crystallization tower A.
It is kept high at about 10 ° C. The temperature of the slurry passing through the cooler 46 is about 10 ° C. or lower, preferably,
The temperature is lowered below 5 ° C. On the other hand, the temperature of the slurry passing through the heater 51 is raised here by about 0.5 to 5 ° C. Microcrystal adduct dissolution tank Q attached to crystallization tower C
Inside, the crystallite adduct component having a particle size of 100 μm or less is dissolved, and the slurry in which the crystallite component is dissolved is returned to the crystallization tower C through the line 53, and the growth of the crystal is promoted. In this crystallization tower C, the content of fine crystal components having a particle size of 10 μm or less is 30% by weight or less, preferably 2
Coarse seed crystals having a good hue of 0% by weight or less are produced.

A part of the slurry withdrawn from the bottom of the inner cylinder P in the crystallization tower C passes through a line 52, a line 61 and a line 62 to form a second crystal forming a second stage crystallization system. Analysis tower D
Is introduced into the lower part of where the crystal growth takes place. The second crystallization tower D is operated in the same manner as the crystallization tower A described above. In the crystallization tower D, the crystallization temperature is 45 to 70.
The temperature is 0 ° C, which is lower than the temperature of the crystallization tower C by about 0 to 10 ° C and higher than that of the crystallization tower B by about 0 to 10 ° C. On the other hand, the temperature of the slurry passing through the heater 71 is increased by about 0.5 to 5 ° C. here. In the fine crystal adduct dissolution tank Q attached to the crystallization tower D, the particle size is 100 μm.
The slurry in which the crystallite adduct component of m or less is dissolved and the crystallite component is dissolved is returned to the crystallization tower through the line 73, and the crystal is grown. The concentration of the crystal adduct in the slurry extracted from the bottom of the inner cylinder P in the crystallization tower D is 35% by weight or less, preferably 25% by weight or less, and the crystal adduct has a particle size of 100 μm or less. The content of the components is 30% by weight or less, preferably 2
0% by weight or less. The slurry extracted from the bottom of the inner cylinder P in the crystallization tower D is recovered as a product slurry through the line 80. This slurry is subjected to solid-liquid separation as necessary, and the obtained crystal adduct is sent to a bisphenol A recovery step to remove phenol and recover bisphenol A.

[0012]

INDUSTRIAL APPLICABILITY According to the present invention, APHA1 with high purity can be obtained.
A good bisphenol A / phenol crystal adduct having a hue of 5 or less can be obtained in high yield. This bisphenol A / phenol crystal adduct gives bisphenol A having a high purity and a good hue by separating and removing phenol therefrom. In the present invention, two crystallization towers are used in one crystallization step, seed crystals are deposited in the first crystallization tower, and seed crystals are deposited in the second crystallization tower at a temperature lower than that of the first crystallization tower. Crystal growth of crystals promotes deterioration of the hue of crystal adducts. Reduces the production rate of fine crystal adducts that have a large amount of adsorption of color-causing substances, and reduces the amount of adsorption of color-causing substances. It is possible to increase the production rate of crystal adducts and easily obtain a high-purity crystal adduct having a good hue, as compared with the case where the crystallization step is performed using one crystallization tower. When it is attempted to obtain a crystal adduct having a good hue similar to that obtained in the present invention by using one crystallization step using one crystallization tower in a plurality of stages, the crystallization step is performed in the crystallization step used in the present invention. More crystallization steps than the steps are required. For example, in order to obtain the same effect as the two-column one-stage crystallization step according to the present invention, two or more one-column crystallization steps are required. The number of steps for separating and re-dissolving the crystal adduct also increases, and eventually the apparatus system becomes complicated and large. Further, in the present invention, the phenol used in the re-dissolving step of the crystal adduct, without using the mother liquor after the separation of the crystal adduct, since using a phenol of higher purity than that, a crystal adduct with an improved hue is obtained. It becomes possible to obtain.

[Brief description of the drawings]

FIG. 1 shows an example of an apparatus system diagram for implementing the present invention.

[Explanation of symbols]

 A, B, C, D Crystallization tower E Solid-liquid separation device F Crystal adduct dissolution tank P Inner cylinder Q Microcrystal adduct dissolution tank

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Sachio Asaoka 2-12-1, Tsurumi Chuo, Tsurumi-ku, Yokohama-shi, Kanagawa Chiyoda Kakoh Construction Co., Ltd. (56) Reference JP-A-1-213246 (JP, A) Japanese Patent Publication No. Sho 53-9585 (JP, B2) Japanese Patent Publication No. Sho 55-19204 (JP, B2) "Encyclopedia of Chemical Equipment Encyclopedia" edited by the Committee for Chemical Equipment Encyclopedia (Chemical Industry Co., Ltd. May 25, 1976) Issued) p104

Claims (1)

(57) [Claims] 1. A phenol solution in which bisphenol A is dissolved is supplied to a first crystallization tower (A) of two crystallization towers connected in series for performing the first crystallization step, and bisphenol A is supplied.・ Particle size consisting of crystalline adduct of phenol 10
A coarse seed crystal having a fine crystal component content of 0 μm or less and 30% by weight or less is precipitated, and the crystallization product containing the seed crystal obtained in this crystallization step is introduced into the second crystallization tower (B). The crystal growth of the seed crystal is performed at a temperature lower than that of the first crystallization tower (A) to generate a coarse crystal adduct having a grain size of 100 μm or less and a fine crystal component content of 30% by weight or less. 1
The crystallization product obtained in the step crystallization step is introduced into the solid-liquid separation step to separate the crystal adduct from the mother liquor, and the crystal adduct is then redissolved in phenol having a higher purity than the mother liquor. The particle size of the bisphenol A / phenol crystal adduct, which is supplied to the first crystallization tower (C) of the two crystallization towers connected in series for performing the two-stage crystallization step, is 1
A coarse seed crystal having a fine crystal component content of 00 μm or less and 30 wt% or less is precipitated, and the crystallization product containing the crystal adduct obtained in this crystallization step is introduced into the second crystallization tower (D). The crystal growth of the seed crystal is performed at a temperature lower than that of the first crystallization tower (C) to generate a coarse crystal adduct having a grain size of 100 μm or less and a fine crystal component content of 30 wt% or less. A method for producing a bisphenol A / phenol crystal adduct having a good hue.