JP3171465B2 - 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 the 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). It is also known to remove phenol from adducts. In such a method for producing bisphenol A, the purity and hue of bisphenol A recovered as a product greatly depend on the purity and hue of the crystal adduct, and a method for producing a crystal adduct with high purity and good hue is demanded. . In order to obtain a high-purity crystalline adduct from a phenol solution containing bisphenol A obtained by reacting excess phenol with acetone, a method of treating the phenol solution by a crystallization step is known. In the conventional method for producing a crystal adduct, one crystallization tower is used in the crystallization step, and a higher purity crystal adduct can be obtained by increasing the size of the crystallization tower. . However, in this case, when the size of the crystallization tower is increased, the size of the cooling device, the crystal adduct circulation device, and the microcrystal adduct dissolution tank are also exponentially increased according to the increase in the size of the crystallization tower. This necessitates the problem that the crystallizer system becomes inefficient, the size of the system increases, and the cost of the system increases.

[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 with 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, there is provided a method for producing a bisphenol A / phenol crystal adduct using n (n ≧ 2) crystallization towers having an inner cylinder provided with an opening at an upper part thereof. Depositing a bisphenol A / phenol crystal adduct in the crystallizer to form a slurry of the crystal adduct, (b) extracting the crystal adduct slurry from the bottom of the inner cylinder of each crystallizer, (c) extracting each crystal Cooling a part of the obtained crystal adduct slurry and circulating the slurry into the lower part of each crystallization tower; (d) crystallization of at least the n-th crystallization tower among the first to n-th crystallization towers Heating a part of the crystal adduct slurry extracted from the tower, dissolving the microcrystalline adduct particles contained in the slurry, and then circulating the melt into the lower part of the crystallization tower; (e) first stage Cooled circulated to the crystallization tower Be supplied to the lower portion of the first stage of crystallization析塔by adding raw material liquid composed of a phenol solution containing bisphenol A into the crystallization adduct slurry, (f) from the first stage the (n-1) th stage A part of the crystal adduct slurry extracted from the bottom of the inner cylinder of each crystallization tower is added to the circulating cooling line of the crystal adduct slurry in the next crystallization tower , and is added to the lower part of each next crystallization tower . (G) using a part of the crystal adduct slurry extracted from the bottom of the inner cylinder of the n-th crystallization tower or a part of the heated circulating slurry in the n-th stage as a product crystal adduct slurry A method for producing a bisphenol A / phenol crystal adduct having a good hue, characterized in that it is collected.

Next, the present invention will be described with reference to the drawings. FIG. 1 shows an apparatus system diagram when the present invention is carried out using two (n = 2) crystallization towers. In this figure, A indicates a first-stage crystallization tower, and B indicates a second-stage crystallization tower.

[0006] Each of the crystallization towers A and B has an inner cylinder P having an opening provided therein at an upper portion thereof. Each of the crystallization towers A and B is provided with a microcrystalline adduct melting tank Q. In each of the crystallization towers A and B that are operating in a steady state, a crystal adduct is precipitated inside the crystallization towers A and B, and a slurry of the crystal adduct is formed. In addition, each crystallization tower A, B
The crystal adduct slurry is withdrawn from the bottom of the inner cylinder P through the respective lines 3 and 23, and a part of the slurry is pumped out of the pumps 4 and 24, the lines 5 and 25, the coolers 6 and 26, and the line 2 , 22 and circulated in each crystallization tower A, B,
Thereby, the slurry in the crystallization towers A and B is cooled,
Each of the crystallization towers A and B is cooled to a predetermined temperature.

[0007] A part of the slurry containing the crystal adduct extracted from the inner cylinder P in each of the crystallization towers A and B is supplied to the lines 7 and 27, the pumps 8 and 28, the lines 9 and 29, and the line 1
0 and 29 and the heaters 11 and 31 are introduced into the fine crystal adduct melting tank Q, where the fine crystal particles of the crystal adduct are dissolved, and the slurry containing the coarse crystal adduct of a certain size is supplied to the line 13. , 33, and is circulated to the lower part of the crystallization towers A and B, whereby the particle diameters of the crystal adducts contained in the crystallization towers A and B are uniformed.
In B, a crystal adduct having a low content of fine crystal adduct particles and a high content of coarse crystal adduct particles is generated.
After dissolving the crystal adduct slurry in the dissolution tank Q, the operation of circulating the crystal adduct slurry to the crystallization tower may be performed at least in the final stage, and may be omitted in other stages of the crystallization tower as necessary. it can.

[0008] The microcrystalline adduct in the crystallization towers A and B has a large specific surface area and exhibits high adsorptivity to coloring substances. Therefore, by reducing the content of microcrystalline adduct particles in the crystal adducts obtained in the crystallization towers A and B as much as possible, a crystal adduct with good hue can be obtained. According to the study of the present inventors, the content of microcrystalline adduct particles having a particle size of 100 μm or less in the crystalline adduct was 30%.
It has been found that a high-purity crystalline adduct with a good hue can be produced by keeping the content at not more than 20% by weight, preferably not more than 20% by weight. When circulating and introducing the temperature-lowered slurry passing through the lines 2 and 22 and the temperature-raised slurry through the lines 13 and 33 into the crystallization towers A and B, the outer cylinders from the lower part of the outer cylinders of the crystallization towers A and B So as to generate a swirling flow in the same direction. In this case, the introduction is preferably performed so as to be tangential to the inner peripheral surface of the outer cylinder, and the introduction positions are different. In addition, the introduction positions of these two slurries are represented by angles from the center point of the outer cylinder, and preferably,
It is preferable to perform the measurement at a position 90 to 180 degrees apart. Furthermore, if a swirling flow in the same direction occurs, the introduction positions of the two slurries need not necessarily be on the same horizontal plane, and there may be a slight difference in height at least at the lower part of the outer cylinder. .

As described above, the slurries passing through the lines 2 and 22 and the lines 13 and 33 are supplied to the crystallization towers A and B such that their introduction directions are tangential to the inner peripheral surfaces of the crystallization towers A and B.
B, causing the slurry in the crystallization towers A and B to generate a swirl flow, which rises to the upper end of the inner cylinder P, and then flows from the upper opening of the inner cylinder P to the inner cylinder P. And is pulled out from the bottom of the inner cylinder P. Crystallization towers A and B
The following effects can be obtained by generating such a swirling flow in the inside. (1) Two liquid streams at different temperatures can be effectively and uniformly mixed. (2) Since the drift of the slurry is prevented and the slurry concentration in the outer cylinder becomes uniform, unevenness in the residence time of the crystal adduct particles in the outer cylinder can be eliminated. (3) A linear velocity sufficient to prevent sedimentation and deposition of crystal adduct particles in the outer cylinder can be obtained.

In the present invention, the raw material solution comprising a phenol solution containing bisphenol A is used in the first stage crystallization tower A.
Is added to the slurry cooled through the cooler 6 circulated to the crystallization tower A of the first stage.

In the present invention, a part of the slurry extracted from the bottom of the inner tube P of the first-stage crystallization tower A is circulated to the second-stage crystallization tower B. The slurry is added to the cooled slurry through the cooler 26 and supplied to the second-stage crystallization tower B. By supplying the slurry obtained from the first-stage crystallization tower A to the second-stage crystallization tower B in this way, efficient cooling of the supplied slurry is achieved, and the cooling heat Is used for the growth of crystal adduct particles, so that the degree of supersaturation of the liquid is reduced and the particle size distribution of the crystal adduct particles can be increased.

The composition of the phenol solution containing bisphenol A used as a raw material liquid in the present invention is usually bisphenol A: 7 to 50% by weight, preferably 10 to 30% by weight.
And contains about 8% by weight or less of bisphenol A isomer, trisphenol and the like as other trace components. The temperature of the phenol solution containing bisphenol A supplied from the line 1 is about 1 to 20 ° C. higher than the saturation temperature of the adduct, and the temperature of the crystallization tower A is 45 to 70 ° C. The temperature of the slurry circulated through the line 3, the pump 4, the cooler 6 and the line 2 is reduced to about 10 ° C. or less, preferably 5 ° C. in the cooler 6.
It is lowered about more than under. The residence time of the phenol solution in the crystallization tower A is 0.5 to 10 hours, preferably 0.5 to 5 hours.
Time.

On the other hand, line 7, pump 8, line 10,
Slurry introduced through the heater 11 in the microcrystalline adduct dissolution tank Q, in the heater 11 is raised its temperature about 0.5 to 5 ° C., microcrystalline adduct dissolve tank <br/> click Q Is held. The residence time of the slurry in this tank Q is about 3 to 15 minutes. In the microcrystal dissolution tank Q, a crystal adduct having a particle size of 100 μm or less is dissolved, and the slurry in which the microcrystals are dissolved is returned to the crystallization tower A through the line 13 to promote crystal growth.

A part of the slurry extracted from the bottom of the inner cylinder P in the first-stage crystallization tower A passes through the line 7, the pump 8, the line 12 and the line 21, and then passes through the cooler 26. The slurry is added to the slurry circulated through the crystallization tower B and introduced into the second crystallization tower B. This second-stage crystallization tower B comprises:
The operation is performed in the same manner as described for the crystallization tower A. The temperature of the crystallization tower B is maintained at a temperature lower by 3 to 10 ° C. than the temperature of the crystallization tower A.

On the other hand, the temperature of the slurry passing through the heater 31 is raised by about 0.5 to 5 ° C., whereby the temperature of the microcrystalline adduct melting tank Q attached to the crystallization tower B is reduced. It is maintained at a temperature higher by about 0.5 to 5 ° C. than the temperature of B. In the microcrystal adduct dissolution tank Q attached to the crystallization tower B, the crystal adduct having a particle size of 100 μm or less is dissolved, and the slurry in which the microcrystals are dissolved is returned to the crystallization tower B through the line 33. The crystal growth of the crystal adduct is promoted. 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 microcrystalline adduct having a particle size of 100 μm or less in the crystal adduct. The particle content is at most 30% by weight, preferably at most 20% by weight.

A part of the slurry extracted from the bottom of the inner tube P in the second crystallization tower B is recovered as a product slurry through a line 35. 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. The product slurry can be withdrawn from the bottom of the second-stage inner cylinder P as described above.
A part of the heated circulating slurry circulated through the circulating device can be recovered as a product slurry.

FIG. 1 shows an apparatus system diagram in the case where the method of the present invention is carried out using two crystallization towers A and B, but the same applies when a larger number of crystallization towers are used. Can be implemented. That is, when performing a crystallization operation using n (n ≧ 2) crystallization towers, the raw material liquid is added to the cooled crystal adduct slurry circulated to the first crystallization tower, and
A part of the crystal adduct slurry extracted from the bottom of the inner cylinder of each of the crystallization towers from the first stage to the (n-1) th stage is supplied to the crystallization tower of the next stage, A part of the crystal adduct slurry which is added to the circulating cooling slurry in the crystallization tower and supplied to each crystallization tower of the next stage, and is extracted from the bottom of the inner cylinder of the crystallization tower of the nth stage (final stage) Alternatively, a part of the circulating slurry heated in the n-th crystallization tower is recovered as a product slurry. In this case, the temperature of the crystallization tower is set such that the temperature of the first-stage crystallization tower is the highest, the temperature of the n-th crystallization tower is the lowest, and It is kept low sequentially toward the n-th stage. The temperature difference between each crystallization tower and each subsequent crystallization tower is 3-10 ° C, preferably 5-8 ° C,
The temperature of the crystallization tower in each subsequent stage is kept low by this temperature difference.

[0018]

According to the present invention, a bisphenol A / phenol crystal adduct with high purity and good hue can be obtained in high yield. This bisphenol A / phenol crystal adduct gives bisphenol A with high purity and good hue by separating and removing phenol therefrom.

[0019]

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

Example 1 A slurry containing a crystal adduct was obtained from a phenol solution containing bisphenol A according to the apparatus system diagram shown in FIG. 1, and the crystal adduct was separated and recovered from the slurry.
The main operating conditions in this case are shown below in relation to the lines or devices indicated by reference numerals in FIG. (1) Component composition of feedstock in line 1 Bisphenol A: 22% by weight Phenol: 74% by weight Others: 4% by weight (2) Crystallization tower A (i) Temperature: 54 ° C (ii) Residence time: 120 minutes ( 3) Microcrystalline adduct melting tank attached to crystallization tower A (i) Temperature: 55 ° C (ii) Residence time: 6 minutes (4) Crystallization tower B (i) Temperature: 47 ° C (ii) Residence time: 120 Minutes (5) Microcrystalline adduct melting tank attached to crystallization tower B (i) Temperature: 48 ° C (ii) Residence time: 6 minutes

In the above experiment, the hue of the crystalline adduct separated from the slurry obtained through line 35 was
The content of the fine particle component having a particle size of 100 μm or less in 15 APHA and the crystal adduct was 13% by weight.

Comparative Example 1 In the apparatus shown in FIG. 1, a crystal adduct slurry was produced using only the first-stage crystallization tower A. In this case, the operating conditions of the crystallization tower A are as follows: the temperature is 47 ° C., and the temperature of the microcrystalline adduct melting tank Q attached to the crystallization tower A is 48
The temperature was the same as in Example 1 except that the temperature was changed to ° C. The hue of the crystal adduct obtained in this experiment was 30 APHA, and the proportion of the fine particle component having a particle size of 100 μm or less in the crystal adduct was 29% by weight.

[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 Crystallization tower P Inner cylinder Q Microcrystalline adduct melting tank

──────────────────────────────────────────────────続 き Continuation of the front page (72) Inventor Sachio Asaoka 2-1-1, Tsurumichuo, Tsurumi-ku, Yokohama-shi, Kanagawa Prefecture Inside Chiyoda Kako Construction Co., Ltd. (58) Field surveyed (Int.Cl. ⁷ , DB name) C07C 39/16 C07C 37/70 C07C 37/82 C07C 37/84 C07C 39/04

Claims (1)

(57) [Claims] 1. An n having an inner cylinder provided with an opening at an upper part.
A method for producing a bisphenol A / phenol crystal adduct using (n ≧ 2) crystallization towers, comprising: (a) depositing a bisphenol A / phenol crystal adduct in each crystallization tower to form a slurry of the crystal adduct; (B) extracting the crystal adduct slurry from the bottom of the inner cylinder of each crystallization tower; (c) cooling a part of the extracted crystal adduct slurry and then circulating it to the lower part of each crystallization tower (D) heating at least a part of the crystal adduct slurry extracted from the crystallization tower of the n-th stage among the crystallization towers of the first to n-th stages to be included in the slurry to circulate into the lower portion of the crystal析塔was dissolved microcrystalline adduct particles, phenolic solvent comprising (e) cooling the crystalline adduct slurry bisphenol a is recycled to the first stage of crystallization析塔Be added to the raw material liquid composed of the supply to the lower part of the first stage of crystallization析塔, (f) disconnect from the (n-1) th stage inner cylinder bottom portion of each crystal析塔from the first stage Adding a part of the discharged crystal adduct slurry to a circulating cooling line of the crystal adduct slurry in each of the next-stage crystallization towers and supplying it to a lower portion of each of the next-stage crystallization towers ; Recovering a part of the crystal adduct slurry extracted from the bottom of the inner cylinder of the eye crystallization tower or a part of the heated circulating slurry in the n-th stage as a product crystal adduct slurry, A method for producing a good bisphenol A / phenol crystal adduct.