JPH05345737A - Production of bisphenol a - Google Patents

Abstract

PURPOSE:To provide the method for producing highly pure bisphenol A. CONSTITUTION:The method contains a reaction process for reacting acetone with an excessive amount of phenol in the presence of an acid catalyst to produce the bisphenol A, a separation process for separating the reaction products, a crystallization process for crystallizing the crystal adduct of the bisphenol A to the phenol, a crystal product-separating process for separating the crystal adduct from the mother liquid, a crystal adductliquidizing process for liquidizing the crystal adduct, a phenol-removing process for removing the phenol from the phenol solution containing the bisphenol A, and a bisphenol A-granulating process for granulating the bisphenol A, and further containing an acetone- circulating process for circulating the acetone separated from the separation process in the reaction process, etc.

Description

Detailed Description of the Invention

[0001]

FIELD OF THE INVENTION The present invention relates to a method for producing bisphenol A.

[0002]

2. Description of the Related Art Bisphenol A [2,2]
It is known to react acetone with excess phenol in the presence of an acid catalyst to produce -bis (4'-hydroxyphenyl) propane]. Further, in order to separate and collect high-purity bisphenol A from this reaction product, the reaction product was crystallized to precipitate a crystal adduct of bisphenol A and phenol (hereinafter, also simply referred to as a crystal adduct), which was obtained. It is also known to remove phenol from crystal adducts (Japanese Patent Publication No. 36-2333).
No. 5, Japanese Patent Publication No. 52-42790). Further, it is also known that the mother liquor (phenol solution) after separating the crystal adduct obtained in the crystallization step is recycled to the reaction step.

By the way, in the mother liquor separated from the crystallization product of the phenol solution containing bisphenol A, in addition to a large amount of phenol and bisphenol A, 2- (2'-hydroxyphenyl) which is an isomer of a small amount of bisphenol A. ) -2- (4'-hydroxyphenyl) -propane (hereinafter, simply referred to as 2,4'-bisphenol A) and the like, trisphenol, high molecular weight polyphenol compounds, including by-products such as chroman compounds, Further, it contains a very small amount of coloring impurities and coloring impurities. Since the mother liquor contains the colored impurities and the easily colored impurities, it is a colored liquid that gives a high coloring density by heating. Since such mother liquor contains phenol as a reaction raw material of bisphenol A and bisphenol A which is a target substance, it is circulated and reused in the reaction system. However, when it is circulated as it is, the by-products, coloring impurities and coloring It is necessary to remove these by-products and impurities because the accumulation of volatile impurities occurs. Therefore, when the mother liquor is recycled to the reaction system, at least a part of the mother liquor is brought into contact with an adsorbent composed of an acid-type cation exchange resin to adsorb and remove the coloring matter, and then the mother liquor is circulated to the reaction system. 55-34779). However, in this method, only a part of the impurities in the mother liquor is adsorbed and removed, so that a considerable amount of by-products and impurities still remain in the circulating mother liquor, and their accumulation cannot be prevented.

According to JP-A-1-230538,
The reaction product obtained by reacting phenol with acetone is first crystallized, a first crystal adduct and a first mother liquor are obtained from the obtained first crystallization product, and phenol is removed from the first crystal adduct. A series of main steps for obtaining bisphenol A,
Isopropenylphenol and phenol were mixed with the first mother liquor, and the reaction product obtained by reacting in the presence of an acid catalyst was subjected to second crystallization, and the second crystallization product thus obtained was used as a second crystal adduct. A second mother liquor is obtained, which is recycled to the first crystallization step by the second crystal adduct, while the second mother liquor is treated by reacting it in the presence of a basic catalyst to contain isopropenylphenol and phenol. A method for producing bisphenol A has been proposed, which comprises a reaction product and a series of sub-processes in which the isopropenylphenol and the phenol are recycled and used. This method uses a substep and does not circulate the mother liquor obtained by crystallization of the reaction product of phenol and acetone into the reaction system of phenol and acetone, so that byproducts and impurities do not accumulate in the reaction system. However, since the by-products other than polyphenol and the accumulation of impurities occur in the sub-step, the purity of the second crystal adduct obtained in the sub-step becomes poor. Also, the second
In order to increase the purity of the crystal adduct, it is necessary to discharge a part of the second mother liquor from the sub-step to the outside of the system. In this case, the mother liquor contains bisphenol A, phenol and polyphenol. Therefore, there is a problem that the loss of those useful components occurs.

[0005]

DISCLOSURE OF THE INVENTION According to the present invention, a series of organically bonded steps effectively prevent the accumulation of by-products and impurities in the reaction system and obtain bisphenol A of high purity. It is an object of the present invention to provide a method for manufacturing the above.

[0006]

The present inventors have completed the present invention as a result of intensive studies to solve the above problems. That is, according to the present invention, a reaction step in which acetone and an excess amount of phenol are reacted in the presence of an acid catalyst to produce bisphenol A, and the reaction product obtained from the reaction step is mixed with acetone and water. , A separation step of separating phenol and a phenol solution containing bisphenol A, a crystallization step of precipitating a crystal adduct of bisphenol A and phenol from the phenol solution containing bisphenol A, and a crystallization obtained in the crystallization step The crystallization product separation step of separating the crystal adduct and the mother liquor from the product, the crystal adduct liquefaction step of liquefying the crystal adduct obtained in the crystallization product separation step, and the bisphenol A obtained in the crystal adduct liquefaction step Dephenoling step for removing phenol from phenol containing solution and bisphenol A obtained from the dephenoling step A step of granulating bisphenol A for granulation, further comprising an acetone circulation step of circulating the acetone separated from the separation step to a reaction step, and separating at least a part of the phenol obtained in the separation step into a crystallization product. Phenol circulation step of circulating as a crystal adduct cleaning liquid in the step, mother liquor circulation step of circulating the mother liquor obtained in the separation step with the crystallization product to the reaction step, mother liquor purification step of purifying a part of the circulated mother liquor and the mother liquor There is provided a method for producing bisphenol A, which comprises a purification mother liquor step of circulating the purification mother liquor obtained in the purification step to a reaction step.

Next, the present invention will be described with reference to the drawings. FIG. 1 is a process diagram for producing bisphenol A according to the present invention. In FIG. 1, 1 is a reaction step, 2
Is a separation step, 3 is a crystallization step, 4 is a crystallization product separation step,
5 is a liquefaction process, 6 is a dephenoling process, 7 is a granulation process,
8 is a distillation step, 9 is a heating step, and 10 is a reduced pressure recovery step.

In the reaction step 1, acetone is reacted with an excess amount of phenol in the presence of an acid catalyst to produce bisphenol A. As the acid catalyst, a mineral acid such as hydrochloric acid or sulfuric acid, or a strong acid type ion exchange resin having a sulfonic acid group is used, but a strong acid type ion exchange resin is preferably used. The amount of phenol used is 8 to 20 mol, preferably 10 to 18 mol, per 1 mol of acetone. The reaction temperature is 50 to 90 ° C. The reaction product obtained in this reaction step 1 is a bisphenol A which is a target product, as well as a bisphenol compound such as 2,4'-bisphenol A which is an isomer of bisphenol A, a trisphenol compound and a high molecular weight polyphenol. It contains compounds, chroman compounds, and by-products such as water, and further contains coloring impurities and coloring impurities. The typical composition of this reaction product is as follows: unreacted phenol: 60 to 90
wt%, preferably 70-80 wt%, unreacted acetone: 0.1-2 wt%, preferably 0.5-1.5 wt
%, Bisphenol A: 15 to 30 wt%, preferably 18 to 25 wt%, water: 0.1 to 2 wt%, preferably 0.5 to 1.5 wt%, by-product polyphenol compound: 2
-15 wt%, preferably 5-10 wt%. This reaction product is introduced into separation step 2 through line 11.

The separation step 2 is a step of separating the reaction product obtained in the reaction step 1 into a phenol solution mainly containing acetone, water, phenol and bisphenol A. The acetone separated in this separation step 2 is circulated to the reaction step 1 through the line 12, water is discharged through the line 13, and phenol is discharged through the line 1.
4 is introduced into the crystallization product separation step 4 as a washing phenol, and the phenol solution containing bisphenol A is introduced into the crystallization step 3 through the line 15. Separation step 2 is usually composed of a distillation treatment step including a plurality of distillation columns, and any separation step may be adopted as long as it is configured to separate the reaction product into the above-mentioned specific components. it can. FIG. 2 shows a distillation treatment system diagram of the reaction product preferably adopted as the separation step 2 of the present invention. In FIG. 2, 31 is a first distillation column, 32 is a second distillation column, 3
3 is a 3rd distillation column, 34 is a 4th distillation column, 35 is a strong acid type ion exchange resin treatment apparatus, and 36 and 37 are stationary tanks.

The reaction product obtained in the reaction step 1 in which the reaction between phenol and acetone is carried out through a line 38.
Introduced into the first distillation column 31 constituting the first distillation treatment step, in the first distillation column 31, unreacted phenol,
Column bottoms (I) containing bisphenol A and by-products, and column tops (I) containing unreacted phenol, unreacted acetone and water
Separated into and.

The component composition of the overhead product (I) from the first distillation column is as follows: phenol: 60 to 90 wt%, preferably 8
0 to 90 wt%, acetone: 2 to 20 wt%, preferably 5 to 10 wt%, water: 5 to 20 wt%, preferably 5
10 to 10 wt%. On the other hand, the bottom product from the first distillation column
The component composition of (I) is as follows: phenol: 50-80 wt
%, Preferably 65-75 wt%, bisphenol A:
18-30 wt%, preferably 20-25 wt%, by-product: 5-20 wt%, preferably 5-10 wt%.

The overhead product (I) obtained in the first distillation column is introduced into a second distillation column 32 constituting a second distillation treatment step through a line 40, while in the first distillation column 31. The obtained bottom product (I) (phenol solution containing bisphenol A) is withdrawn through a line 39 and sent to the crystallization step 3 as a crystallization raw material through a line 15 in FIG.

In the second distillation column 32, distillation treatment is carried out in the presence of an oily azeotropic agent to obtain a column top product (II) consisting of acetone, water and an azeotropic agent. The component composition of the column top (II) is acetone: 2 to 20 wt%, preferably 5 to
20 wt%, water: 10-30 wt%, preferably 15-
25 wt%, azeotropic agent: 40-80 wt%, preferably 50-70 wt%. From the bottom of the tower, the bottom product (II)
As a result, phenol is obtained. The content of acetone in the bottom product (II) of the second distillation column 32 is 5 wt% or less, preferably 0%. The azeotropic agent is preferably present in a small amount, particularly 5% by weight or less, preferably 1% by weight or less, in the bottom product of the second distillation column by adjusting the operating conditions of the second distillation column. As a result, the amount of phenol mixed in the column top product can be reduced.

Top product from the top of the second distillation column 32 (II)
Is a stationary tank 36 that constitutes a stationary step through a line 42.
And is separated into an oily component consisting of acetone and an azeotropic agent and an aqueous component consisting of acetone and water. The oil component separated in the stationary tank 36 is introduced into the third distillation column 33 through the line 44, and the aqueous component is introduced into the third distillation column 33 through the line 45. By separating the overhead (II) of the second distillation column 32 into the oil component and the aqueous component by the stationary tank 36, the overhead (II) can be stably supplied to the third distillation step. However, it is not always necessary to install the stationary tank 36, and the column top product (II) can be directly supplied to the third distillation column through the line 42. On the other hand, the bottom product (II) composed of phenol from the second distillation column 32 passes through the line 41 and, if necessary, through the strong acid type ion exchange resin treatment device 35, constitutes the fourth distillation treatment step. 4 is introduced into the distillation column 34.

The oily azeotropic agent has a boiling point range of 80 to 1.
Hydrocarbon oils at 40 ° C, preferably 100-140 ° C are used. Specific examples of the azeotropic agent include toluene, ethylbenzene, xylene and the like. As described above, this azeotropic agent supplies the necessary amount for circulating the second distillation column 32 and the third distillation column 33 through the line 43 into the column from the outside of the system when the operation of the second distillation column 32 is started. After the operation is started, it is separated in the stationary tank 37 and then returned to the second distillation column 32 through the line 43.

Third distillation column 3 constituting the third distillation treatment step
At 3, acetone is obtained as overhead (III), which is withdrawn through line 46 and is recycled to reaction step 1 through line 12 shown in FIG. The water content in this circulating acetone is 5 wt% or less, preferably 3 wt% or less. On the other hand, a bottom product (III) consisting of water and an azeotropic agent is obtained from the bottom of the third distillation column 33.
This product is introduced into a stationary tank 37 which constitutes a stationary process through a line 47, and is separated into an azeotropic agent and water here. The azeotropic agent is circulated to the second distillation column 32 through the line 43. On the other hand, the water is discharged through the line 48. The content of acetone contained in this waste water is 5 wt% or less, preferably 0%.

In the strong acid type ion exchange resin treatment device 35, the strong acid type ion exchange resin serves as a catalyst to condense the colored impurities contained in the bottom product (II) (phenol) and the colored impurity precursors. The reactive impurities undergo a condensation reaction and are converted into tar-like high-boiling substances. In this case, examples of condensable impurities include benzofuran. As the strong acid type ion exchange resin, a gel type resin 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 Company, Diaion etc. available from Mitsubishi Kasei Co. can be preferably used. Treatment of the bottom product (II) using this strong acid type ion exchange resin is a method of circulating the bottom product (II) into a packed column containing a strong acid type ion exchange resin, or a stirring tank containing a strong acid type ion exchange resin. It can be carried out by, for example, a method in which the bottom product (II) is put in and stirred. Processing temperature is 45-15
0, preferably 50 to 100 ° C. The contact time between the strong acid type ion exchange resin and the bottom product (II) is 5 to 200 minutes, preferably about 15 to 60 minutes. When treating the column bottoms (II) using this strong acid type ion exchange resin, the column bottoms
When water is mixed in (II), the effect of removing impurities by the strong acid type ion exchange resin decreases. In this distillation treatment method, as described above, in the second distillation column 32, water is almost completely separated as a tower top component, and the phenol obtained as a column bottom product contains substantially water. Therefore, the strong acid type ion exchange resin treatment of the bottom product (II) is smoothly carried out.

The strong acid type ion exchange resin processing device 35 includes
If necessary, pass the crude phenol through line 49,
It can be introduced as a mixture with the bottom product (II) passing through the line 41. Unrefined phenols include industrial phenols,
Examples include mother liquor phenol and washing waste liquor phenol obtained in the crystallization step.

The treated product obtained in the strong acid type ion exchange resin treatment unit 35 is introduced into the fourth distillation column 34 through a line 50, and the column overhead (IV) consisting of phenol,
It is separated into a bottom product (IV) consisting of tar-like high-boiling substances. The operating conditions of this distillation column must be such that phenol and the high-boiling substance can be completely separated, and it must be performed under the condition that the high-boiling substance is not mixed in the phenol. The point to be noted in this case is to set the distillation treatment temperature to 190 ° C. or lower. If the temperature is 190 ° C or lower, the operating pressure is set arbitrarily, but usually 50 Tor
A reduced pressure or normal pressure of r to 760 Torr is adopted. If the operating temperature exceeds 190 ° C., decomposition of high-boiling substances and the like becomes remarkable and the quality of distillate phenol is deteriorated, which is not preferable. In the fourth distillation column 34, 95% by weight or more, preferably 99% by weight or more of the introduced phenol is distilled. Phenol obtained from the top of the fourth distillation column 34 has a good hue, and its hue APHA is 1
It is 0 or less. This purified phenol is extracted through a line 52, and at least a part thereof is introduced into a crystallization product separation step 4 through a line 14 shown in FIG. 1 as a cleaning liquid for a crystal adduct to obtain high-purity bisphenol A. used. Further, this purified phenol can be recycled and used in the reaction step 1 if necessary. Fourth
The bottom product (IV) extracted from the bottom of the distillation column 34 through the line 51 is usually phenol: 10 to 90% by weight.
And a high-boiling substance: a mixture containing 10 to 60% by weight. Since the amount of this bottom product (IV) is small, it can be discharged as it is out of the system.

According to the step of separating the reaction products shown in FIG. 2, since the distillation in the second distillation column 32 is carried out in the presence of the azeotropic agent, substantially all the amount of water and acetone is removed from the column. It can be separated as the top (II). Then, the column top (II) can be almost completely separated into water and acetone in the third distillation column 33. That is, the third distillation column 33
The substantially total amount of acetone supplied to the third distillation column 33 can be separated as the top product (III) of the third distillation column.
The bottom product (III) of (3) is substantially free of acetone.
As a result, the waste water extracted from the stationary tank 37 does not contain acetone, and the troublesome waste water treatment problem of removing acetone from the waste water is solved. In addition, since acetone is separated from the third distillation column 33 as the top product (III), almost no water is mixed therein, the acetone can be easily reused.

FIG. 3 shows another distillation treatment system diagram which can be adopted as the separation step 2 of the present invention. In FIG. 3, 31 is a first distillation column, 32 is a second distillation column, and 33 is a third distillation column.
A distillation column, 34 is a fourth distillation column, and 35 is a strong acid ion exchange resin treatment device.

The product obtained in the reaction step 1 in which the reaction between phenol and acetone is carried out, through line 38, to the first
The bottom product (I), which is introduced into the first distillation column 31 constituting the distillation treatment step and contains unreacted phenol, bisphenol A and by-products, and the top product containing unreacted phenol, unreacted acetone and water (I) is separated. The first distillation column 31 has a phenol content of 40% in the top (I) thereof.
It is operated so as to be in the range of wt% or less, preferably 30 wt% or less. As a result, the water content in the column product (II) obtained from the second distillation column 32 is 5 wt% or less, particularly 2
It can be suppressed to wt% or less. The component composition of the top product (I) of the first distillation column 31 is phenol: 40w.
t% or less, preferably 30 wt% or less, acetone: 20
~ 45 wt%, preferably 30-40 wt%, water: 20
~ 45 wt%, preferably 30-40 wt%. On the other hand, regarding the component composition of the bottom product (I) of the first distillation column 31, phenol: 55-80 wt%, preferably 65-
75 wt%, bisphenol A: 18 to 30 wt%, preferably 20 to 25 wt%, by-product: 5 to 15 wt%,
It is preferably 6 to 10 wt%. The first distillation column 31
The column top product (I) obtained in (1) is introduced into the second distillation column 32 constituting the second distillation treatment step through the line 40, while
The bottom product (I) obtained in the first distillation column 31 is the line 3
It is introduced into the fourth distillation column 34 through 9.

In the second distillation column 32, acetone is obtained as the overhead product (II), which is withdrawn through the line 46 and circulated to the reaction step 1 through the line 12 shown in FIG. . The water content in this circulating acetone is 1
It is 0 wt% or less, preferably 5 wt% or less. on the other hand,
A bottom product (II) consisting of a mixture of phenol and water is obtained from the bottom of the second distillation column 32.
It is introduced into the third distillation column 33 through 7. Second distillation column 3
The composition of the column bottoms (II) of 2 is phenol: 40-60
wt%, preferably 40-50 wt%, water: 40-60
wt%, preferably 50-60 wt%, and the content of acetone is 1 wt% or less.

Third distillation column 3 constituting the third distillation treatment step
In 3, water is obtained as overhead (III), which is discharged via line 48. On the other hand, the bottom product (III) made of phenol is obtained from the bottom of the third distillation column 33. This product is treated with the strong acid type ion exchange resin treatment device 35 through the line 41, and then the It is introduced into the fourth distillation column 34 which constitutes the four-distillation treatment step. If necessary, unpurified phenol can be added to the bottom product (III) of the third distillation column 33 via the line 49 and introduced into the strong acid ion exchange resin treatment device 35. In this case, examples of the unpurified phenol include industrial phenol, mother liquor phenol obtained in the crystallization step, and washing waste liquor phenol.

In the strong acid type ion exchange resin treatment device 35, the strong acid type ion exchange resin serves as a catalyst to cause condensation reaction of the condensable impurities such as the colored impurities and the colored impurity precursors contained in phenol to generate tar. It is converted to high boilers. The treatment product obtained in the strong acid ion exchange resin treatment device 35 is introduced into the fourth distillation column 34 constituting the fourth distillation treatment step through the line 50, and phenol is obtained as the column top (IV) there. It Further, the bottom product (I) of the first distillation column 31 (phenol solution containing bisphenol A) is introduced into the fourth distillation column 34 through a line 39. In the fourth distillation column 34, phenol is distilled out from the top of the column, and this phenol has a good hue and its hue APHA is 10 or less.
At least a part of this purified phenol is circulated to a crystallization product separation step 4 through a line 14 as shown in FIG. 1 and used as a cleaning liquid for a crystal adduct to obtain high-purity bisphenol A. Further, this purified phenol can be recycled and used in the reaction step 1 if necessary. The bottom product (IV) extracted from the bottom of the fourth distillation column 34 through the line 51 is usually 1 bisphenol.
5 to 30 wt%, preferably 20 to 25 wt%, and phenol to 50 to 80 wt%, preferably 65 to
75% by weight, and 5 to 15% by weight, preferably 6 to 10% by weight, by-products are introduced into the crystallization step 3 as a crystallization raw material through a line 15 as shown in FIG. To be done. The bottom product (I) of the first distillation column 31
Is not introduced into the fourth distillation column 34 and is used as it is in the crystallization step 3
Can also be introduced to.

According to the separation step of the reaction product shown in FIG. 3, by keeping the phenol content in the overhead product (I) obtained from the first distillation column 31 at 40% by weight or less,
Substantially all of the acetone supplied to the second distillation column 32 can be separated as the top product (II) of the second distillation column, and the bottom product (II) of the second distillation column 2 is substantially There is no mixing of acetone. As a result, in the third distillation column 33, the water separated as the column top (III) does not contain acetone, and the troublesome problem of wastewater treatment such as removing acetone from the separated water is solved. . Further, according to this separation step, since acetone does not exist in the third distillation column, the distillation operation can be efficiently performed.

In the crystallization step 3, the solution containing the bisphenol A obtained in the separation step 2 as described above is cooled,
In this step, a crystal adduct of bisphenol A and phenol is deposited. In this case, the crystallization temperature is 35-80.
C., preferably 45 to 70.degree. The crystallization product (crystal adduct slurry) obtained in this crystallization step is introduced into the crystallization product separation step 4 through line 16 in FIG. Crystallization process 3 can consist of one or more crystallization stages, a crystallization diagram for one example of which is shown in FIG. In FIG. 4, 55 is an outer cylinder,
56 is an inner cylinder, 57 is a microcrystal adduct dissolution tank, 58 is a cooler, 59 is a heater, 60 and 61 are pumps, and A is a crystallization tower. The crystallization tower A has a double cylinder structure in which an inner cylinder 56 having an opening at the top is inserted into an outer cylinder 55 having a closed structure. The closed structure referred to in this specification means a state in which the crystallization tower is not open to the atmosphere but is sealed with an inert gas. When the crystallization tower A is open to the atmosphere, a part of oxygen in the atmosphere is absorbed by the slurry in the crystallization tower, which deteriorates the hue of the adduct and further adversely affects the subsequent treatment, resulting in high It becomes impossible to obtain a quality adduct and thus a high quality bisphenol A. Therefore, in the crystallization tower A, in order to prevent the mixing of oxygen,
It becomes necessary to seal with inert gas. in this case,
If the mixture of oxygen can be prevented, it is not always necessary to use a closed pressure-resistant container that can withstand high pressure. Further, in the crystallization tower A, instead of directly providing an extraction hole in the outer cylinder part, an inner cylinder is provided on the central axis of the swirling flow of the slurry inside,
It is advisable to increase the swirling flow of the slurry to the upper part, overflow the slurry from the opening in the upper part of the inner cylinder, lower the inside of the inner cylinder, and then withdraw it from the bottom part of the inner cylinder. As a result, it is possible to ensure uniform mixing of the introduced circulating slurry and sufficient residence time for the adduct particles.

In order to carry out the crystallization process according to the crystallization system diagram shown in FIG. 4, first, the separation process 2 to the line 1 in FIG.
A part of the phenol solution containing bisphenol A as the raw material to be treated extracted through 5 is filled in the crystallization tower A through lines 62 and 63, and the inner cylinder 5
The phenol solution is withdrawn from the bottom of 6 through a line 64 and continuously circulated in the outer cylinder below the crystallization column A through a line 65, a pump 60, a line 66, a cooler 58, a line 67 and a line 63. . By this operation,
The phenol solution in the crystallization tower A is cooled, the crystal adduct is crystallized, and a slurry containing the crystal adduct is produced.
This slurry is extracted from the bottom of the inner cylinder 56, cooled by the cooler 58 as described above, and then circulated in the outer cylinder 55 below the crystallization tower A. Further, a part of the slurry is passed from the bottom of the inner cylinder 56 through the line 64, the line 68, the pump 61, the line 69, the heater 59, the tank 57 and the lines 70, 71 into the outer cylinder 55 below the crystallization tower A. Circulate continuously. By this operation, the fine crystal adduct particles in the slurry extracted from the bottom of the inner cylinder 56 are dissolved in the tank 57, and the slurry having a low content rate of the fine crystal adduct particles is circulated in the crystallization tower A. As a result, the content of the fine crystal adduct particles in the crystallization tower A is reduced.

Next, under such a condition, bisphenol A extracted from the separation step 2 through the line 15
A phenol solution containing is introduced into the outer cylinder 55 below the crystallization tower A through lines 62 and 63,
The product slurry is extracted from the bottom of the inner cylinder 56 through the line 73. In this case, when this slurry can be flowed to the next crystallization product separation step by gravity flow, it is extracted using the line 73 in this way, but if not, a part of it is discharged from the discharge line 74 of the pump 61. It can also be extracted. Further, a part of the slurry having a small content of fine crystals can be recovered from the line 72 and used as a product crystal adduct slurry. These crystal adduct slurries can be subjected to the same crystallization treatment as described above, if necessary.

When the temperature-reduced slurry passing through the line 63 and the temperature-increasing slurry passing through the lines 70 and 71 are introduced into the outer cylinder 55, they are introduced into the outer cylinder from below the outer cylinder.
It is preferable to introduce so as to generate swirling flows in the same direction.
In this case, preferably, the introduction is performed so as to be tangential to the inner peripheral surface of the outer cylinder, and the introduction positions are different. If the introduction position is too close, local turbulence of the flow occurs, a smooth swirling flow cannot be obtained, and it is not preferable from the viewpoint of the structure and strength of the crystallization tower. Therefore,
The introduction position of these two slurries is preferably expressed by an angle from the center point of the outer cylinder, preferably 90 to 180 degrees apart. Further, if swirling flows in the same direction are generated, the introduction positions of the two slurries do not necessarily have to be on the same horizontal plane, and at least in the lower part of the outer cylinder, there may be a slight difference in height. Absent. As described above, when the respective slurries passing through the line 63 and the lines 70 and 71 are introduced into the outer cylinder so as to generate a swirling flow in the same direction, the swirling flow moves in the outer cylinder 55 and the upper end of the inner cylinder 56. The inner cylinder 5 from the upper opening of the inner cylinder 56.
6 descends and is withdrawn through the line 64 from the bottom of the inner cylinder. By producing such a swirling flow in the outer cylinder 55, the following effects can be obtained. (1) Two liquid streams having different temperatures can be effectively and uniformly mixed. (2) Since uneven flow of the slurry is prevented and the slurry concentration in the outer cylinder becomes uniform, it is possible to eliminate unevenness in the residence time of the crystal adduct particles in the outer cylinder. (3) It is possible to obtain a sufficient linear velocity for preventing the sedimentation and deposition of the crystal adduct particles in the outer cylinder.

Further, as described above, a part of the slurry extracted from the bottom of the inner cylinder 56 is transferred to the line 64, the line 68,
A pump 61, a heater 59, a tank 57 and a line 70,
When circulating to the crystallization tower A through 71, the fine crystal adduct in the slurry is dissolved and disappears in the tank 57, so that the slurry containing the coarse crystal adduct of a certain size passes through the lines 70 and 71 to the crystallization tower. The crystal is circulated to A, whereby the particle size of the crystal adduct contained in the crystallization tower A is made uniform, and the crystallite A has a low content of fine crystal adduct particles and a high content of coarse crystal adduct particles. An adduct is generated. Since the microcrystalline adduct in the crystallization tower A has a large specific surface area, it exhibits a high adsorptivity for the color-causing substance. Therefore, by reducing the content ratio of the fine crystal adduct particles in the crystal adduct obtained in the crystallization tower A as much as possible, a crystal adduct having a good hue can be obtained. By maintaining the content of the fine crystal adduct particles having a particle size of 100 μm or less in the crystal adduct at 30% by weight or less, preferably 20% by weight or less, a high-purity crystal adduct having a good hue can be produced.

The temperature of the phenol solution containing bisphenol A supplied from the line 62 is about 1 to 20 ° C. higher than the saturation temperature of the crystal adduct, and the temperature of the crystallization tower A is 45 to 70 ° C. Line 65, pump 60,
In the cooler 58, the temperature of the slurry circulated through the cooler 58 and the line 63 is about 10 ° C. or less,
It is preferably lowered by about 5 ° C. or less. The residence time of the phenol solution in the crystallization tower A is 0.5 to 10 hours, preferably 0.5 to 5 hours. On the other hand, the slurry introduced into the microcrystal adduct dissolution tank 57 through the line 68, the pump 61, the line 69, and the heater 59 is the heater 5
In 9, the temperature is raised by about 0.5 to 5 ° C. and held in the microcrystal dissolution tank 57. The retention time of the phenol solution in the tank 57 is about 3 to 15 minutes.

In the fine crystal dissolution tank 57, crystal adducts having a grain size of 100 μm or less are dissolved. Line 7
Particle size in the crystal adduct in the slurry passing through 0
The content of the crystalline adduct particles below is 30% by weight or less, preferably 20% by weight or less.

According to the crystallization method, it is possible to efficiently generate a crystal adduct having a low hue of fine crystal adduct particles and a good hue. This crystalline adduct gives bisphenol A having a good hue by separating and removing phenol therefrom.

The crystal adduct slurry (crystallization product) obtained in the crystallization step 3 is sent to the crystallization product separation step 4. In the crystallization product separation step 4, the crystal adduct slurry is separated into the crystal adduct and the mother liquor, and the crystal adduct is washed using the purified phenol extracted from the separation step 2 through the line 14 as a washing liquid. It is processed. Then, the separated mother liquor is withdrawn from the crystallization product separation step 4 through the line 17 and is recycled to the reaction step 1 together with the washed phenol, if necessary.
In this case, at least part of the circulating mother liquor, usually 1-20
The weight% is introduced into the mother liquor purification step to be described later for treatment. Then, the purified mother liquor is circulated to the reaction step 1 again.

In the crystallization product separation step 4, when the crystalline adduct slurry is filtered to separate the crystalline adduct from the mother liquor, among the crystalline adducts contained in the slurry, the fine crystalline adduct component having a particle size of 100 μm or less is used. At least part of it is transferred to the filtrate (mother liquor) side, and the particle size is 100μ
The proportion of the microcrystalline adduct component of m or less is 20% by weight or less,
It is preferable to obtain a coarse crystal adduct of preferably 15% by weight or less. In this case, in order to transfer the microcrystalline adduct component to the filtrate side, it can be carried out by selecting a filter (filter material) or filtering operation conditions. As a filter, its opening is generally 100-300μ.
m, preferably 150 to 250 μm. Further, when the microcrystalline adduct component is transferred to the filtrate side according to the filtration operation condition, the transfer amount of the microcrystalline adduct component should be adjusted by the thickness of the crystal adduct cake obtained by the filtration treatment and the frequency of backwashing the cake. You can

The crystal adduct obtained as described above is of high quality with a low content of impurities by itself, and this crystal adduct was further extracted from separation step 2 through line 14. The quality can be further improved by washing with purified phenol. The cleaning of the crystal adduct with the purified phenol may be any method that can sufficiently bring the contact between the crystal adduct and the purified phenol. This washing treatment is carried out, for example, by removing the mother liquor from the crystal adduct in a solid-liquid separator such as a filter or a centrifuge for separating the crystal adduct, and then introducing purified phenol into the solid-liquid separator. It is also possible to clean the adduct adhering a small amount of mother liquor discharged from the solid-liquid separation device with purified phenol in another stirring tank. The ratio of the purified phenol to the crystal adduct is 50 parts by weight or more, preferably 100 parts by weight or more, based on 100 parts by weight of the crystal adduct.

The crystal adduct washed with purified phenol is a crystal composed of an equimolar composition of bisphenol A and phenol.
Dephenoling step 6 after forming a phenol solution containing
Where it can be stripped of phenol to give the highly pure product bisphenol A. Further, this bisphenol A is further sent to the granulation step 7, where it can be made into a granulated product of bisphenol A.

By filtering the crystal adduct slurry and cleaning the crystal adduct, it is possible to efficiently remove highly adsorbable impurities such as coloring substances and coloring substances adhering to the surface of the crystal adduct. In addition, it is possible to easily obtain a crystal adduct having an excellent hue and having good thermal stability that hardly causes coloring. In addition, bisphenol A obtained by removing phenol from the crystal adduct also has a high hue and is of a high quality which hardly causes coloring.

The mother liquor obtained from the crystallization product separation step 4 as described above is circulated to the reaction step 1 through lines 17 and 19 shown in FIG. 1, and at least a part of the circulated mother liquor is used. Is extracted from a line 17 and is purified through a line 18 by (i) distillation step 8, (ii) heating step 9 and (iii) reduced pressure recovery step 10 and strong acid ion exchange resin step R. Although the heating step 9 and the reduced pressure recovery step 10 can be carried out independently of each other,
Preference is given to carrying out simultaneously using a reaction column.

FIG. 5 shows a processing system diagram for one example of the purification processing method of the mother liquor extracted through the lines 17 and 18 of FIG. In FIG. 5, 8 is a phenol distillation column, D is a reaction column having a reaction tank 6 and a reduced pressure evaporation column 7, and R is a strong acid ion exchange resin column. Raw material mother liquor is line 1
It is introduced into the phenol distillation column 8 through 8. In this case, as the raw material mother liquor, at least a part of the mother liquor obtained in the crystallization product separation step 4 can be used. In the crystallization treatment of a phenol solution containing bisphenol A, a plurality of stages of crystallization steps and a solid-liquid separation step of a crystallization product are usually adopted, and a plurality of mother liquors (phenol solution) are accordingly used.
In the present invention, any of these mother liquors can be used as the raw material mother liquor. The preferable raw material mother liquor used in the present invention is the first mother liquor obtained in the first crystallization step.
This is the mother liquor separated from the crystallization product. The mother liquor separated from the first crystallization product is usually a fail: 85% by weight, bisphenol A: 5-10% by weight, other polyphenols containing 2,4-bisphenol A: 1-5% by weight, chroman Coloring impurities such as compounds: 2% by weight or less Coloring impurities that are converted into colored substances by heating such as aldehydes and quinones: A trace amount is contained.

The phenol distillation column 8 has a temperature of 100 to 2
The operation is carried out under the conditions of 00 ° C., preferably 120 to 185 ° C., pressure: 50 Torr to normal pressure. In the phenol distillation column 5, 50 to 90% by weight, preferably 65 to 85% by weight, of the raw material mother liquor introduced through the line 18 is distilled. If the amount of distillate exceeds this range, the viscosity becomes high and the bottom solidifies,
If the amount is less than this range, the concentration of phenol will increase and the processing efficiency and the thermal efficiency in the heating step and reduced pressure recovery step will decrease. The distillate vapor from the phenol distillation column 8 is condensed in a condenser 85 attached to this distillation column, and a part of it is returned to the distillation column 8 as a reflux liquid through the line 86, and the remaining condensate is condensed. The (distillate) is introduced into the reduced pressure condenser 90 attached to the reaction tower D through the line 87. The distillate passing through this line 87 consists essentially of 100% phenol. On the other hand, from the bottom of the phenol distillation column 8 to the line 81
The bottom liquid is extracted through the line 8 and the bottom liquid together with the basic catalyst supplied through the line 83.
4 is introduced into the reaction tank 9 at the bottom of the reaction tower D, and at the same time as the reaction of the reactive components contained therein, the concentrated mother liquor containing the product produced by this reaction is evaporated and recovered. The basic catalyst may be supplied directly to the reaction tank 9 of the reaction tower D. The bottom liquid withdrawn from the bottom of the phenol distillation column 8 through the line 81 is
Usually, phenol: 10 to 50% by weight, preferably 15
~ 30% by weight, balance bisphenol A, 2,4'-
Consists of bisphenol A, other polyphenols, and other impurities.

In the reaction tower D, polyphenols such as bisphenol and trisphenol contained in the concentrated mother liquor are thermally decomposed by the action of a basic catalyst in the reaction tank 9 and are converted into isopropenylphenol and phenol. A polycondensation reaction of impurities such as chroman compounds occurs, and the impurities are converted into high-boiling substances. Examples of the basic catalyst include hydroxides, oxides, carbonates, various phenol salts of alkali metals such as sodium and potassium, hydroxides, oxides, carbonates, various phenols of alkaline earth metals such as calcium and magnesium. Salt etc. are mentioned. The proportion of the basic catalyst used is 0.005 to 0.8% by weight, preferably 0.01 to 0.5% by weight, based on the total polyphenol containing bisphenol A in the concentrated mother liquor extracted through the line 81. Is.

The reaction tower D has a structure in which a reaction tank 9 is provided at the bottom and a reduced pressure evaporation tower 10 is erected on the reaction tank. This reaction tower D has a bottom (reaction tank) temperature of 200 to 350.
C., preferably 220 to 300.degree. C., column pressure: 5 torr to normal pressure, preferably 10 to 150 torr. The distillate vapor containing phenol and isopropenylphenol extracted from the top of the reaction tower D through a line 89 is introduced into a vacuum condenser 90 attached to the reaction tower D, where the phenol distillation tower 8 draws a line. 87 is mixed with the introduced distillate and brought into contact with the distillate to be rapidly cooled, and then introduced into the strong acid ion exchange resin tower R through a line 91.
The temperature of the distillate sent from the phenol distillation column 8 to the vacuum condenser 90 through the line 87 is 45 to 150 ° C, preferably 50 to 110 ° C. The amount of the distillate passing through the line 87 is 1 to 20, preferably 2 to 15 by weight ratio with respect to the distillate vapor passing through the line 89. Line 89
The components of the distillate vapor extracted from the reaction column D through the reactor are phenol, isopropenylphenol, bisphenol A and other impurities. The bottom liquid (reaction liquid) extracted from the reaction column D through the line 88 is 0.05 in weight ratio with respect to the liquid supplied to the reaction column D through the line 84.
˜0.5, preferably 0.05 to 0.4, and the high-boiling substance (having a higher boiling point than bisphenol A) and the coloring substance are concentrated in this bottom liquid.
The mixed liquid in the reduced pressure condenser 90 is introduced into the strong acid type ion exchange resin tower R through a line 91. In this strong acid type ion exchange resin tower R, bisphenol A is produced by the reaction of isopropenylphenol and phenol contained in the mixed liquid. The product containing bisphenol A is discharged through a line 92 and introduced into the circulating mother liquor line 19 shown in FIG. 1 or the reaction step 1 through a line 25.

As the strong acid type ion exchange resin, a gel type one having a sulfone group is used, and such a strong acid type ion exchange resin is well known in the prior art.
For example, Amberlite and Amberlyst available from Rohm and Haas Company, Diaion etc. available from Mitsubishi Kasei Co. can be preferably used. In the reaction of the mixed solution using this strong acid type ion exchange resin,
The reaction temperature is 45 to 130 ° C, preferably 50 to 10 ° C.
0 ° C., contact time 5 to 200 minutes, preferably 15
~ 120 minutes. When the reaction of the mixed solution using the strong acid type ion exchange resin is performed, the water content in the mixed solution is 0.5% by weight or less, preferably 0.1% by weight or less. The component of the reaction product extracted from the strong acid ion exchange resin tower R through the line 92 is phenol: 85 to 95% by weight,
Bisphenol A: 5 to 15% by weight, preferably 5 to 1
0% by weight, other impurities: Trace amount and low coloring property. This is recycled to reaction step 1 through line 25, as shown in FIG. If necessary, a part thereof can be concentrated and crystallized to obtain a bisphenol A / phenol crystal adduct. The strong acid type ion exchange resin column R is not always necessary, and the top product of the reactive distillation D can be directly circulated in the reaction step 1.

As shown in FIG. 6, the reaction tower D is preferably used with a heat treatment apparatus A and a retention tank B attached thereto. In such operation of the reaction tower D, a part of the bottom product is withdrawn from the reaction tank 9 at the bottom of the reaction tower D through the line 96, and a part of the withdrawn bottom product. Is introduced into the heat treatment apparatus A through the line 97 as the first circulating liquid, is subjected to the heat treatment there, and then is circulated to the reaction tank 9 of the reaction tower D through the lines 94 and 95. In the heat treatment apparatus A, the first circulating liquid is 200
It is heated to a temperature of ~ 350 ° C, preferably 230-300 ° C. By this heating, the polyphenol contained in the first circulating liquid undergoes the above-mentioned thermal decomposition reaction. The residence time of the first circulating liquid in the heat treatment apparatus A is 1 to 30.
Minutes, preferably 1 to 20 minutes. On the other hand, reactive distillation column D
Part of the column bottoms extracted from the bottom of the column is the line 98, the line 99, the retention tank B and the line 10 as the second circulating liquid.
It is circulated to the reaction tank 9 of the reaction tower D through 0. Retention tank B
In, the second circulating liquid is held at a temperature of 200 to 300 ° C., preferably 220 to 280 ° C. for 5 to 120 minutes, preferably 10 to 100 minutes. By this retention treatment, when the depolymerization of the polyphenol contained in the mother liquor is insufficient, the depolymerization proceeds further, and when the color-causing substance, for example, the chroman compound is insufficiently heavier, It is possible to obtain the effect that the heaviness progresses and is converted into a high boiling point tar-like substance that can be easily separated. The circulation amount of the first circulating liquid is 50 to 5000 parts by weight with respect to 100 parts by weight of the concentrated mother liquor supplied to the reaction column D through the line 100, while the circulating amount of the second circulating liquid is 10
It is from 1 to 10,000 parts by weight, preferably from 50 to 5,000 parts by weight.

In the method for treating the mother liquor described above, impurities contained in the mother liquor are passed through the line 23 (FIG. 1) or the line 88 (FIG. 5, FIG. 6) connected to the bottom of the reaction tower D or the reaction tank 9. , Discharged as concentrated impurities. By-products having a higher boiling point than bisphenol A,
Condensates of condensable impurities are contained, and when a strongly acidic substance having a high boiling point such as an ion exchange resin having a sulfonic acid group is used as a catalyst in the reaction step 1, the sulfonated product liberated from the catalyst is included. Therefore, according to the treatment method of the mother liquor described above, the polyphenol compound contained in the mother liquor, the coloring impurities, the coloring impurities,
Further, the catalyst-derived high-boiling substances (such as sulfonates) used in the reaction step 1 are separated and removed from the mother liquor in a concentrated state. Then, by recycling the mother liquor from which the by-products and impurities have been removed in this way to the reaction step 1 again, the loss of useful components contained in the mother liquor is suppressed and the accumulation of by-products and impurities in the reaction system is prevented. As a result, it is possible to obtain bisphenol A with high purity and in which discoloration is prevented.

The crystal adduct liquefying step 5 is a step of liquefying by heating and melting the crystal adduct. As a melting device for the crystal adduct, an external heating type closed container having a heating jacket on the outer wall surface, an internal heating type closed container having a heating coil inside, or the like is used. This melting apparatus is preferably used after being subjected to a treatment for removing oxygen adhering to the surface of the material forming the inner wall surface, prior to the melt liquefaction of the crystal adduct. As a result, the amount of the coloring-causing substance produced due to heating during melting of the crystal adduct can be significantly suppressed, and high-purity bisphenol A having a good hue can be obtained. The inner wall surface of the melting device is made of a metallic material, usually stainless steel, such as SUS30.
4, SUS316, 316L, etc., and about 30 to 60 millimoles of oxygen per m ² are attached and bonded to the surface thereof. This oxygen content can be measured by various methods. For example, there is also a method of estimating based on the correlation between the cleaning conditions of a test piece and the amount of surface-attached bound oxygen whose depth is measured by surface etching.
It can also be measured from the relationship between the amount of oxygen attached to the surface and the coloration of the washed phenol. Also in the case of other cleaning liquids, the correlation between the coloring and the amount of oxygen adhering to the surface can be determined in advance and used as the measuring method. For example, the coloring of phenol is 6 APHA for 1 part by weight of oxygen and can be used as a correlation for this measurement. The melting device
By removing oxygen adhering to the inner wall surface in advance, it is possible to remarkably suppress the production of a coloring-causing substance caused by heating during melting of the crystal adduct, and to obtain a product bisphenol having a good hue. .

Oxygen can be removed from the inner wall surface of the melting apparatus by cleaning the inner wall surface with an organic solvent. As the organic solvent, phenol, bisphenol A, a mixture of phenol and bisphenol A, or the like can be used. The cleaning treatment temperature is 100 to 20.
The temperature is 0 ° C, preferably 120 to 185 ° C. As an atmosphere for cleaning, a non-oxidizing gas atmosphere such as nitrogen gas, nitrogen gas, argon gas, degassing steam, or a reduced pressure atmosphere is used, and the oxygen concentration in the atmosphere is 0.01 vo
It is 1% or less, preferably 0.005 vol% or less, and more preferably 0.001 vol% or less. The cleaning of the inner wall surface with the organic solvent can be performed by spraying the organic solvent onto the inner wall surface through a spray nozzle. After washing with the organic solvent, the organic solvent remaining at the bottom of the melting device is discharged, and the inside is dried as necessary. In addition, for the measurement of the oxygen concentration in the gas phase, a normal gas chromatography method or a trace oxygen analyzer by an electrochemical method can be used.

In the oxygen removal treatment from the inner wall surface, the amount of oxygen attached to the inner wall surface is preferably 10 mmol or less, preferably 5 mmol or less per 1 m ^{2 of} the inner wall surface. The operating conditions of the melting device are:
Temperature: 115-180 ° C, preferably 120-150
° C, pressure: normal pressure, oxygen concentration: 0.01 vol% or less, preferably 0.005 vol% or less, more preferably 0.
Conditions of 001 vol% or less are adopted. When melting the crystal adduct, a method of liquefying the crystal adduct as it is can be adopted, but in order to melt the crystal adduct in a short time, the crystal adduct is used with a non-colored hot phenol such as purified phenol. It is also possible to employ a method of diluting and melting, a method of melting in a liquid in which the crystal adduct has been melted, or the like.

As the crystal adduct as a raw material to be liquefied in the melting apparatus, it is preferable to use a crystal adduct which is substantially under neutral conditions. In the reaction of acetone and phenol,
Since a strongly acidic substance is used as a catalyst, it is necessary to neutralize the strongly acidic substance present in the reaction product after the reaction so as not to exceed the neutralization point or remove it from the reaction system. Further, when the alkali used for neutralizing the strongly acidic substance remains, it is also necessary to remove this alkali. Further, the strongly acidic substance or the alkali present in the reaction product can be removed in the crystallization step after the reaction step, the crystallization product separation step, or the like. The above-mentioned substantially crystalline adduct under a neutral condition means a crystalline adduct from which the influence of the strongly acidic substance or the alkaline substance is removed. Such a crystal adduct is added to and dissolved in an aqueous methanol solution whose acidity is adjusted to have a pH of 5.0, and the pH is measured in a pH measuring method under substantially non-ionizing conditions of phenol.
4.90-5.50, preferably pH 4.95-5.2
It shows 0. As the crystal adduct, those which are under a substantially neutral condition are used as described above. In this case, it is preferable to maintain the melt color APHA of the crystal adduct at 15 or less. A crystal adduct having a melt color APHA of 15 or less can be obtained by increasing the number of crystallization stages in the crystallization step, and can also be obtained by washing the crystal adduct with purified phenol.

When the crystal adduct is melted and liquefied under substantially neutral conditions, it is preferable to add an aliphatic carboxylic acid. The aliphatic carboxylic acid used in this case has an action of preventing the coloring of bisphenol A when the bisphenol A in a molten state is brought into contact with air for a long time or is kept at a high temperature. By adding an aliphatic carboxylic acid to a crystal adduct under a substantially neutral condition, melting the crystal adduct, and further dephenoling it, it is possible to obtain bisphenol A having an excellent hue and no coloring. As the aliphatic carboxylic acid,
Any material may be used as long as it has an effect of preventing coloring of bisphenol A, and conventionally known materials may be used. Examples of such substances include formic acid, oxalic acid, citric acid, tartaric acid, glycolic acid, lactic acid, malic acid, glyceric acid and the like. These compounds decompose or isomerize at a temperature of 160 ° C. or higher during the reaction, and exhibit an excellent action as a color preventing agent for bisphenol A. The amount of aliphatic carboxylic acid added is
It is 1 to 100 ppm by weight, preferably 5 to 50 ppm by weight, based on the crystal adduct. When the crystal adduct is heated and melted in the presence of oxalic acid or citric acid, the melting temperature is 115 to 180 ° C, preferably 120 to 15 ° C.
It is 0 ° C., and the melting pressure is 1 to 5 atm, preferably 1.0 to 1.9 atm. The melting atmosphere is preferably an atmosphere having an oxygen concentration as low as possible, and usually has an oxygen concentration of 0.005 vol% or less, preferably 0.001 vol.
It is advantageous to use an atmosphere of less than%. The aliphatic carboxylic acid may be added to the crystal adduct, may be added to the crystal adduct slurry before separating the crystal adduct, or may be added to the phenol solution containing bisphenol A obtained by melting the crystal adduct. However, the addition timing is not particularly limited.

The dephenoling step 6 is a step for obtaining bisphenol A by evaporating and removing phenol from the phenol solution containing bisphenol A obtained by liquefying the crystal adduct. Phenol separated in this step is discharged through line 29, and phenol-free bisphenol A is sent through line 28 to granulation step 7. As the evaporator, a distillation tower, a stripping device, a packed tower, a thin film evaporator, or the like is used. As in the case of the melting device, it is preferable that this evaporation device is also used before being used after being subjected to a treatment for removing oxygen attached to the surface of the material forming the inner wall surface thereof. In this case, it is preferable to remove the amount of oxygen attached to the inner wall surface so that the amount of oxygen is 10 mmol or less, preferably 5 mmol or less per 1 m ² of the inner wall surface. Further, in the evaporator, a member for improving the evaporation surface area, for example, if a Raschig ring, a ball ring, a plate, a packing material such as a porous body or a shelf is provided, for those members, It is preferable to perform a treatment for removing oxygen from the surface. The evaporator can be used in a single stage or in multiple stages. The operating conditions for the evaporator are the one stage evaporator when used in one stage and the final stage evaporator when used in multiple stages. As temperature: 180 to 200 ° C., preferably 170 to 18
The conditions are 5 ° C., pressure: 1 to 100 Torr, preferably 5 to 40 Torr, and oxygen concentration in atmosphere: 0.005 vol% or less, preferably 0.001 vol% or less.

One preferable mode of carrying out the dephenoling step is a method of evaporating the crystal adduct melt by combining an evaporation step without steam and an evaporation step with steam. In this evaporation method, the molten liquid from the crystal adduct melting device is
In the absence of steam, evaporation is carried out under reduced pressure, and a part of the phenol in the melt is removed by evaporation. From the top of the first evaporation column, vapor containing phenol is separated and collected, and from the bottom thereof, a molten liquid in which a part of phenol is removed by evaporation is separated and collected. The bottom product from the first evaporation column is introduced into the second evaporation column, where it is subjected to an evaporation treatment under reduced pressure in the presence of steam to evaporate and remove the residual phenol in the melt. From the second evaporation column, a mixed vapor containing phenol, steam and a small amount of bisphenol A is discharged as the top product, and high-purity bisphenol A is separated and recovered as the bottom product. As operating conditions of the first evaporation column without using steam, temperature: 125 to 200 ° C., preferably 130 to 185 ° C., pressure: 100 Torr or less, preferably 5 to 40 Torr is adopted. The oxygen concentration in the vapor atmosphere in the evaporation tower is maintained at 0.005 vol% or less, preferably 0.001 vol% or less. This first
In the evaporation column, 95-99.8% by weight of the phenol present in the crystal adduct melt, preferably 98-9.
9.7% by weight is evaporated off. The operating conditions of the second evaporation column using the steam include temperature: 130 to 200
℃, preferably 160-185 ℃, pressure: 100 Torr or less, preferably 5-40 Torr, steam supply amount per kg bisphenol A melt: 0.02-0.2k
The condition of g, preferably 0.04 to 0.1 kg is adopted. The oxygen concentration in the vapor atmosphere in the evaporation tower is 0.005
It is kept at not more than vol%, preferably not more than 0.001 vol%. In this second evaporation tower, substantially all the amount of phenol in the crystal adduct melt obtained from the first evaporation tower is removed by evaporation, and the phenol content is 2 as the bottom product.
It is possible to obtain bisphenol A of 00 wtppm or less, preferably 50 wtppm or less.

From the second evaporation column using the above steam, steam, phenol and a small amount of bisphenol A are obtained.
A mixed vapor containing is obtained, and phenol and bisphenol A are separated and recovered from this mixed vapor. Separation and recovery of phenol and bisphenol A from this mixed vapor can be carried out by various conventionally known methods, but in the present invention, it is particularly preferable to carry out using a two-stage cooling process. Next, the separation and recovery of phenol from the mixed vapor using this two-stage cooling process will be described in detail. In this method, the mixed vapor obtained from the second evaporation column and containing phenol, steam and a small amount of bisphenol A is supplied to the first cooling step in the reduced pressure state, where phenol or bisphenol A is added. The first cooling medium containing phenol is countercurrently contacted to cool. This first cooling step is carried out so that substantially all the amount of bisphenol A in the mixed vapor is dissolved in the cooling medium. The steam in the mixed vapor is not substantially condensed in this first cooling step and is sent to the next second cooling step. Part of the phenol in the mixed vapor is condensed in this first cooling step, and the remaining uncondensed one is sent to the next second cooling step together with steam. A part of the mixed liquid of bisphenol A and phenol separated and recovered from the mixed vapor in the first cooling step can be used as a cooling medium. The temperature of the first cooling medium is 1 to 50 from the freezing point of phenol.
The temperature is about ℃ higher. The recovery rate of phenol from the mixed vapor in the first cooling step is 70% by weight or more, and preferably 85% by weight or more, based on the total amount of phenol supplied to the first cooling step.

The cooling medium used in the first cooling step may be an amount sufficient to cool the mixed vapor to a desired temperature, and is usually 5 to 10, preferably 6 to 9 by weight ratio to the mixed vapor. is there. Also, the total bisphenol A of bisphenol A contained in the cooling medium in which bisphenol A in the mixed vapor obtained in the first cooling step and phenol are dissolved.
Of phenol to the weight ratio of 0.05 to 0.20,
It is preferably 0.08 to 0.14. In this first cooling step, since excess phenol is present with respect to bisphenol A, the adduct between bisphenol A and phenol does not crystallize even at a cooling temperature below the freezing point of bisphenol A. .

The pressure in the first cooling step is 100 torr or less, preferably 5 to 40 torr, which corresponds to the pressure in the second packed column. Further, the temperature in the first cooling step is a temperature at which steam holds gas and a part of phenol holds liquid under the pressure condition. Preferred cooling temperature (temperature at which bisphenol A is condensed)
Is 42 to 90 ° C, preferably 45 to 55 ° C.

The steam and phenol mixed vapor sent to the second cooling step are cooled by being countercurrently contacted with a second cooling medium consisting of an aqueous solution of phenol. This second cooling step is carried out so that substantially all of the steam and phenol sent to this step are condensed and liquefied, and an aqueous phenol solution is recovered from this step. A part of the aqueous phenol solution obtained in the second cooling step can be used as the second cooling medium. The phenol concentration in the aqueous solution is determined by the composition of the mixed vapor and the conditions of the first cooling step, but it is usually 55 to 75% by weight. The temperature of the second cooling medium is about 1 to 10 ° C. lower than the condensation temperature of steam.

The second cooling medium used in the second cooling step may be an amount sufficient to condense the total amount of the mixed vapor, and is usually the weight of the mixed vapor of steam and phenol sent from the first cooling step. The ratio is 100 to 300, preferably 190 to 250. The pressure of this second cooling step is 100 torr or less, preferably 5 to 40 torr, which corresponds to the pressure of the first cooling step. The cooling temperature (steam condensation temperature) in the second cooling step may be a temperature at which the total amount of steam and phenol mixed vapor is condensed and liquefied under the pressure conditions.

The cooler used in the first cooling step and the second cooling step may be any gas-liquid contact type device, and any one may be used. As such a cooler, for example, a packed tower or a spray tower can be used. When a packed column is used, it is preferable to use a Raschig ring, a pole ring, a porous metal plate, or the like as the packing so as to suppress the pressure loss. Also, the first cooling step and the second
The coolers used in the cooling step may be installed separately, but may be a one-column type device including two coolers.

Next, one embodiment of the method for condensing the mixed vapor will be described with reference to the drawings. In FIG. 7, 101 indicates a first cooler and 102 indicates a second cooler. Line 103 shows a mixed vapor line connected to the second evaporation column using steam. A line 104 is a vacuum line connected to an exhaust pump (not shown) and a cooler, and a first evaporation column (not shown) and a second evaporation column (not shown) that evaporate and remove phenol from the above-described crystal adduct melt. No.), the entire system including the first cooler 1 and the second cooler 2 is kept under reduced pressure. The mixed vapor from the second evaporating tower is supplied to the lower part of the first cooler 101 through a line 103, where the first cooling medium (phenol) introduced from the upper part of the first cooler through a line 105. Or in a countercurrent contact with phenol containing bisphenol A).
The cooling medium in which bisphenol A and phenol which are condensed in the first cooler are dissolved is withdrawn from the bottom of the first cooler through a line 106 including a withdrawal pump 107.
The cooling medium extracted through the line 106 can be recycled to the line 105 as a cooling medium after cooling a part of the cooling medium to a required temperature, if necessary.

The mixed gas of steam and phenol extracted from the top of the first cooler 1 through the line 108 is introduced into the lower part of the second cooler 102, where the line 10
It makes countercurrent contact with a second cooling medium (an aqueous solution of phenol) introduced from the upper part of the second cooler through 9. In this second cooler, steam and phenol mixed vapor is condensed and liquefied,
This condensate is discharged together with the cooling medium from the bottom of the second cooler 102 through a line 110 including a pump 111, and a part thereof is cooled through a line 113 and a cooling medium cooler 114. After passing through the line 109, it is recycled to the second cooler. The remainder of the cooling medium containing condensed steam and phenol extracted through the line 111 is extracted outside the system through the line 112.

Next, FIG. 8 shows a system diagram when a one-column type cooling device including a first cooler and a second cooler is used in the method for condensing the mixed vapor. In FIG. 8, 13
Reference numeral 0 is a one-column type cooling device including the first cooler 101 and the 102nd cooler 2 therein. This cooling device is the first
A partition plate 125 having an opening in the center is disposed between the cooler 1 and the second cooler 2, and a cylindrical body 123 is provided upright in the opening. In this device, the annular hollow chamber formed between the outer peripheral surface of the cylindrical body 123 and the inner wall of the cooling device 130 is for storing the liquid. 122 is
It is a guide plate for guiding the liquid flowing down the second cooler 102 to the annular hollow chamber. The cylindrical space 124 shows a gas passage. In the reference numerals in FIG. 8, the same reference numerals as those shown in FIG. 7 indicate the same meanings. Further, in FIG. 8, the flow rate control system shown in FIG. 7 is not shown.

According to the condensation treatment of the mixed vapor as described above, the mixed vapor containing steam, phenol and bisphenol A obtained from the second evaporation column using steam is depressurized to 100 torr or less without increasing the pressure. It can be cooled and condensed as it is. Moreover, in this case, crystals of bisphenol A and phenol do not precipitate at all, despite the low pressure condition of 100 Torr or less and the low steam condensation temperature condition corresponding thereto. Therefore, in such a condensation treatment method, the efficiency of the cooler is not lowered and the clogging trouble of the cooler due to solid deposition does not occur at all. Moreover, all of the steam, phenol and bisphenol A that compose the mixed vapor are condensed, and the vapor is not substantially introduced into the vacuum exhaust system. Therefore, the vacuum exhaust pump only needs to keep the apparatus system under a predetermined depressurization condition, so that it requires only a small exhaust capacity and is very advantageous in terms of equipment cost and energy cost. Furthermore, when such a condensation treatment of mixed vapor is adopted, the cooling condensation treatment of the mixed vapor can be carried out at an extremely low pressure of 100 Torr or less. Can be done at. Therefore, high-purity bisphenol A having a very low phenol content, for example, a very low-purity bisphenol A having a phenol content of 200 ppm or less, particularly 50 ppm or less, can be obtained from the second evaporation column.

Another preferred method for carrying out the dephenoling step is to subject the crystal adduct melt to evaporation treatment using a plurality of thin film evaporators. This evaporation process will be described below with reference to the drawings. In FIG. 9, 201,
Reference numerals 02 and 203 denote thin film evaporators. This has a structure in which a thin film formed on the inner peripheral wall of the thin film is evaporated by heating from the outside. In this thin film evaporator, it is preferable to use a centrifugal thin film evaporator having a rotary blade inside and forming a liquid film on the inner peripheral wall surface by the rotation of the rotary blade. Further, in FIG. 9, reference numeral 204 is an external heater attached to each thin film evaporator. This one is usually
It is configured as a jacket through which the heating medium flows.

The crystal adduct melt used as a raw material is under substantially neutral conditions and has a melt color of 15 APH.
A phenol solution containing bisphenol A is preferably used by melting the bisphenol A / phenol crystal adduct of A or less by heating or diluting and dissolving with purified phenol. The crystal adduct solution contains bisphenol A in an amount of 50 to 80% by weight, preferably 60 to 7%.
It consists of a phenol solution containing 5% by weight. This raw material phenol solution is introduced into a first thin film evaporator (hereinafter, also simply referred to as an evaporator) 201 from a line 210, and the phenol solution flows down as a liquid film on the inner peripheral wall of the evaporator, and an external heater is provided therebetween. Heated by 204, steam containing phenol and bisphenol A is discharged through line 211. This vapor condenses it to recover phenol and bisphenol A. The temperature of the phenol solution passing through line 210 is 120
˜150 ° C., the temperature of the first evaporator 201 is 160˜18
5 ° C., the pressure is 15-60 torr, preferably 15-
It is 30 torr. Further, the inside of the first evaporator is maintained under substantially oxygen-free conditions. In the first evaporator 201, the residual liquid (bisphenol A) obtained by evaporating the raw material phenol solution is extracted through a line 212,
It is introduced into the evaporator 202. The temperature of the evaporation residual liquid of the phenol solution passing through the line 212 is 170 to 185 ° C. The concentration of phenol in bisphenol A constituting this residual liquid is 1 to 5% by weight. Second evaporator 20
In 2, bisphenol A is added to the third evaporator 203.
While making countercurrent contact with the stripping gas consisting of steam, phenol and bisphenol A extracted from
The stripping gas containing phenol, bisphenol A and steam is heated by the external heater 204 and discharged through the line 213. The temperature in the second evaporator 2 is 170 to 185 ° C. and the pressure is 15 torr or less, usually 10 to 15 torr. Further, the inside of the second evaporator is kept substantially oxygen-free.

The evaporation residual liquid obtained in the second evaporator 2 is introduced into the third evaporator 203 through the line 214. The temperature of this residual liquid is 170 to 185 ° C., and the phenol concentration in bisphenol A constituting the residual liquid is 0.05 to 0.10% by weight, preferably 0.05 to 0.07% by weight. In the third evaporator 203, the bisphenol A from the second evaporator 202 is heated by the external heater 204 in countercurrent contact with the steam introduced through the line 215, and the stripping gas passes through the line 217. This stripping gas is extracted from the second evaporator 20.
2 is introduced as the stripping gas. Third
The temperature in the evaporator is 170 to 185 ° C. and the pressure is 15 torr or less, usually 10 to 15 torr. Further, the inside of the third evaporator is kept substantially oxygen-free. Line 215
The amount of steam introduced from the third to the third evaporator 203 is 3% by weight or more, preferably 4 to 6% by weight with respect to the bisphenol A introduced into the third evaporator 203 through the line 214. Is. The composition of the stripping gas passing through the line 217 is phenol: 0.8 to 1.2% by weight, preferably 1% by weight or less, bisphenol A: 5 to
7% by weight, balance: steam. The high-purity bisphenol A obtained in the third evaporator 203 is
It is extracted through 6. This bisphenol A has a phenol content of 0.005% by weight, and its hue A
It is of high quality with a PHA of 20 or less.

The stripping gas extracted from the second evaporator 202 through the line 213 is subjected to a condensation treatment, and the phenol and bisphenol A contained in the gas are separated and recovered. The stripping gas condensing process is preferably performed according to the system diagrams shown in FIGS. 7 and 8.

In the method using the thin film evaporator described above, a phenol solution containing bisphenol A derived from a phenol A / phenol crystal adduct is first subjected to the first thin film evaporation under the condition that the oxygen concentration in the atmosphere is 0.005 vol% or less. Evaporate using a vessel, the phenol content is 1 ~
5% by weight of bisphenol A is obtained, in which case the temperature of the first thin film evaporator is 160-185 ° C. and the pressure is 15
Since the condition was maintained at -60 Torr, even if the phenol was cooled by rapid evaporation, bisphenol A could be smoothly evaporated without precipitation. Further, in the above method, the bisphenol A obtained from the first evaporator as described above is
In order to remove the phenol contained therein by evaporation, steam stripping treatment is carried out using a thin film evaporator. In this case, the phenol content in bisphenol A is as low as 1 to 5% by weight, and two thin film evaporators are used. Since they were used in series, the temperature of these evaporators was increased to 170
It is possible to evaporate and remove the phenol in bisphenol A by maintaining it at ˜180 ° C. and in a high vacuum of 15 Torr or less, which has an excellent hue and a phenol content of 0.005% by weight. The following high-purity bisphenol A can be obtained.

In order to obtain biphenol A having an excellent hue, the phenol solution containing bisphenol A, which is a raw material for producing the biphenol A, and the temperature at which the solution is subjected to evaporation treatment are set to 1
It is necessary to keep the temperature below 90 ° C, especially below 185 ° C to suppress the formation of colored impurities such as inpropenylphenol. In the case of the above method, the evaporation treatment temperature is kept below 185 ° C. Further, since the inside of the evaporator is kept substantially oxygen-free to substantially completely remove the phenol by evaporation, the obtained bisphenol A has a high purity of APHA20 or less and an excellent hue. Further, in the above method, the stripping gas consisting of steam containing phenol and bisphenol A produced in the third thin film evaporator is used as the stripping steam gas for the second thin film evaporator. There is also an advantage that the phenol stripping effect in the above becomes high. Furthermore, according to the above-mentioned evaporation treatment, the residence time as a whole is extremely short (usually 60 to 12).
Since the evaporation treatment can be performed in 0 second), the treatment efficiency is extremely high. In particular, it is desirable that the first thin film evaporator, the second thin film evaporator, and the third thin film evaporator combine them in this order from the upper side so that the flow of the liquid flows down from the upper side to the lower side by gravity. Can be effectively prevented, and the residence time of the liquid in the system can be kept short.

The granulating step 7 is a step of molding the bisphenol A obtained in the dephenoling step into granules. As this granulation step, any step can be adopted as long as it is a method capable of granulating bisphenol A. In general, a method is adopted in which a molten liquid of bisphenol A is dropped in the form of droplets in an inert atmosphere for cooling, and is cooled and solidified during that period. The particle size of the bisphenol A granules is usually about 0.5 to 5 mm. Further, when granulating bisphenol A, a small amount of a crystal nucleating agent that promotes solidification of crystals of molten droplets of bisphenol A can be added, if necessary.

[0072]

EXAMPLES The present invention will now be described in more detail by way of examples.

(I) Reaction Step 1 According to a conventionally known method, acetone and phenol were reacted in the presence of an ion exchange resin having a sulfonic acid group. In this case, 14 mol of phenol was used per 1 mol of acetone. The reaction was carried out at 60 ° C. The composition of the reaction product thus obtained was as follows. Bisphenol A: 0.8 wt% Water: 1.0 wt% Phenol: 73.6 wt% Bisphenol A: 18.8 wt% Others: 5.8 wt%

(II-1) Separation step (FIG. 2) According to the system diagram shown in FIG. 2, the reaction product of phenol and acetone obtained in the reaction step 1 was subjected to a distillation treatment. The main operating conditions used at this time are shown below in relation to the line or apparatus shown in FIG. (1) Column top (I) passing through the line 40 (i) Component composition Acetone: 5.8 wt% Phenol: 7.2 wt% Water: 86.1 wt% Others: 0.9 wt% (2) Tower passing through the line 42 Top (II) (i) Component composition Acetone: 18.5 wt% Water: 22.5 wt% Entropy agent: 55.6 wt% Others: 3.4 wt% (3) Bottom product (II) (3) passing through line 41 i) Component composition Phenol: 99.0 wt% Azeotropic agent: 0.5 wt% Others: 0.5 wt% (4) Column top (III) passing through the line 46 (i) Component composition Acetone: 85.1 wt% Water: 1.0 wt% Others: 13.9 wt% (5) Wastewater passing through the line 48 (i) Composition of water: 99.95 wt% Phenol: 0.05 wt%

(II-2) Separation step 2 (FIG. 3) The reaction product of phenol and acetone obtained in the reaction step 1 was treated according to the system diagram shown in FIG.
The main operating conditions used at this time are shown below in relation to the line or apparatus shown in FIG. (1) Column top (I) that passes through line 40 (i) Component composition Acetone: 29.0 wt% Water: 38.8 wt% Phenol: 29.9 wt% Others: 2.3 wt% Line (2) Column top product (II) passing through 46 (i) Component composition Acetone: 89.7 wt% Water: 2.1 wt% Others: 8.2 wt% (3) Bottom product passing through line 47 (II) (i) ) Component composition Water: 55.5 wt% Phenol: 44.2 wt% Others: 0.3 wt% (4) Column top (III) passing through the line 48 (i) Component composition Water: 99.7 wt% Phenol : 0.2 wt% Others: 0.1 wt% (5) Column bottom product (III) passing through the line 41 (i) Component composition Phenol: 99.0 wt% Others: 1.0 wt%

(III) Crystallization Step 3 (FIG. 4) According to the system diagram shown in FIG. 4, a phenol solution containing bisphenol A is crystallized to obtain a slurry (crystallized product) containing crystal adducts. It was The main operating conditions in this case are shown below in relation to the lines or devices indicated by the symbols in FIG. (1) Component composition of feedstock in line 62 Bisphenol A: 22 wt% Phenol: 74 wt% Others: 4 wt% (2) Crystallizer A (i) Temperature: 50 ° C (ii) Residence time: 120 minutes ( 3) Microcrystal adduct dissolution tank 5 attached to crystallization tower A
7 (i) Temperature: 51 ° C. (ii) Residence time: 6 minutes In the above experiment, the proportion of fine particles having a particle size of 100 μm or less in the crystal adduct separated from the slurry obtained through the line 73 was 20% by weight. there were.

(IV) Crystallized Product Separation Step 4 The crystal adduct slurry obtained by crystallizing a phenol solution containing bisphenol A was treated with a filter equipped with a filter cloth having an opening of 106 μm to obtain a slurry temperature. Was filtered under reduced pressure while maintaining at 50 ° C., and the obtained crystal adduct cake was washed with the purified phenol obtained from the separation step 2 in (II-1) above. The proportion of the fine crystal adduct component of 100 μm or less in this washed crystal adduct was 5% by weight. The melting color of this crystal adduct is 1
At 0 APHA, the concentration of colored impurities was remarkably low. The concentration of the chroman compound (coloring impurity) contained in this crystal adduct was 100 wtppm.

(V) Purification treatment of mother liquor separated from crystallization product (FIG. 5) The mother liquor separated from the crystallization product of the phenol solution containing bisphenol A was treated according to the apparatus system diagram shown in FIG. . The main operating conditions used at this time are shown below in connection with the line or apparatus shown in FIG. (1) Mother liquor passing through line 18 (i) Component composition Phenol: 86.3% by weight Bisphenol A: 7.7% by weight 2,4'-bisphenol A: 2.4% by weight Other trisphenols, polyphenols, coloring impurities and Coloring impurities, etc .: 3.6% by weight (ii) Hue APHA: 500 or more (2) Phenol distillation column (5) (i) Column bottom temperature: 170 ° C. (ii) Pressure: 170 Torr (3) Pass through line 11 Distillate (i) Component composition Phenol: 99.8 wt% or more (ii) Hue APHA: 10 (4) Bottom product (concentrated mother liquor) passing through line 81 (i) Component composition Phenol: 14.8 wt% Bisphenol A: 48.5% by weight 2,4'-bisphenol A: 14.8% by weight Other trisphenols, polyphenols, coloring impurities and coloring impurities, etc .: 21. 9 wt% (ii) Hue APHA: 500 or more (5) Addition amount of basic catalyst (NaOH) in line 83: 0.05 wt% with respect to concentrated mother liquor passing through line 81 (6) Reacting distillation column (D) ) (I) Bottom temperature: 250 ° C. (ii) Pressure: 40 Torr (7) Distillate vapor passing through line 89 (i) Component composition Phenol: 92.6% by weight Isopropenylphenol and others: 7.4% by weight (Ii) Hue APHA: 200 (8) Bottom liquid passing through the line 88 (i) Component composition Phenol: 0.5 wt% Bisphenol A: 5.5 wt% Other polyphenol high-boiling substances: 90 wt% or more ( ii) Withdrawal amount: 1 for concentrated mother liquor passing through line 81
7.0 wt% (9) Strong Acid Ion Exchange Resin Tower (R) (i) Temperature: 53 ° C (ii) Pressure: 760 Torr (10) Product Passing through Line 92 Phenol: 89.5 wt% Bisphenol A: 8.0 wt% Other impurities: 2.5 wt% (ii) Hue APHA: 70 or less

(VI-1) Crystal Adduct Liquefaction Step 6 and Dephenolization Step 7 of Crystal Adduct Melt Liquid SUS304 external heating closed container is used as a crystal adduct melting apparatus, and SUS304 stripping apparatus is used as an evaporator. Was used. A crystal adduct supply pipe was attached to the upper part of the melting device, and a melt liquid pipe was attached to the bottom thereof, and this melt liquid pipe was connected to the middle part of the stripping device. Further, a pipe for discharging phenol vapor was attached to the upper part of the stripping device, and a pipe for discharging a melt of bisphenol A was attached to the bottom part thereof. All the above-mentioned pipes were made of SUS304. Next, in the apparatus system configured as described above, the inner wall surface of the melting device, the inner wall surface of the stripping device, the piping between the melting device and the stripping device, and the bisphenol A melting attached to the stripping device. The inner wall surface of the liquid discharge pipe was washed as follows. (1) Cleaning of inner wall surface of melting device After injecting a phenol solution at 130 ° C onto the inner wall surface through a spray nozzle under normal pressure to sufficiently clean the inner wall surface, a phenol / bisphenol A mixed solution at 150 ° C ( A mixed weight ratio: 65/35) was sprayed to thoroughly clean the inner wall surface. (2) Cleaning of the inner wall surface of the stripping device Under normal pressure, 130 ° C phenol was made to flow from the spray nozzle attached to the upper part of the device to clean the center part of the device, then 130 ° C phenol and then 150 ° C. Phenol / Bisphenol A mixture (mixing weight ratio = 65
/ 35) so that the wall surface of the device was sufficiently wet. Then, at 180 ° C and 10 Torr, a phenol / bisphenol A mixture (mixing weight ratio = 65/35)
Was distributed. (3) Cleaning of the inner wall surface of the pipe Phenol at 130 ° C was circulated in the pipe for cleaning.
At that time, care was taken so that the gas phase did not exist on the inner wall surface of the tube.
By the above cleaning, it was confirmed that the amount of oxygen attached to the inner wall surface of each device and the pipe was 5 mmol or less per 1 m ² of the inner wall surface.

Next, as described above, the purified crystal adduct (melted APHA : 5) was removed by evaporation of phenol to separate bisphenol A (experiment A). Further, the operating conditions of the melting device and the stripping device in the above are as follows. (Melting device) Temperature: 130 ° C. Pressure: Normal pressure Atmospheric oxygen concentration: 0.0005 vol% (Stripping device) Temperature: 175 ° C. Pressure: 10 torr Atmospheric oxygen concentration partial pressure: 0.0015 vol%

For reference, the same experiment was carried out (Experiment B) except that the inner walls of the melting device, the stripping device and the pipe were not washed. Next, the melting color of bisphenol A obtained in Experiment A and Experiment B at 175 ° C. is summarized in the following table.

[0082]

[Table 1]

(VI-2) Crystal Adduct Liquefaction Step 6 and Dephenolization Step 7 of Crystal Adduct Melt Liquid As a crystal adduct dissolution apparatus, an external heating type closed container made of SUS316 is used, and as a vapor treatment apparatus for crystal adduct melt liquid, S filled with a filler made of SUS316 inside
Two packed columns made of US304 were used. In the melting device,
A crystal adduct supply pipe was attached to the upper part thereof, a melt liquid pipe was attached to the bottom thereof, and this pipe was connected to an intermediate portion of the first packed column. This first packed column is equipped with a pipe for discharging phenol vapor at the top of the column and bisphenol A at the bottom thereof.
A melt liquid pipe containing phenol and phenol was attached, and this pipe was connected to the middle part of the second packed column. A pipe for discharging mixed vapor containing phenol, steam and a small amount of bisphenol A was attached to the top of the second packed column, and this pipe was connected to the cooling condenser shown in FIG. Also, at the bottom of the second packed column, a bisphenol A discharge pipe,
A steam supply pipe was attached. A heating coil for circulating heating steam was arranged at the bottom of each of the first packed tower and the second packed tower. Further, each of the above-mentioned pipes was made of SUS316.

Next, in the apparatus system constructed as described above, the inner wall surface of the melting apparatus, the first packed tower and the second
Inner wall surface of the packed tower and the surface of the packing material, piping between the melting device and the first packed tower, piping between the first packed tower and the second packed tower, and bisphenol arranged at the bottom of the second packed tower The A discharge pipe was subjected to a cleaning treatment for removing attached oxygen as follows. (1) Cleaning of the inner wall surface of the melting device After injecting a phenol liquid at 130 ° C. onto the inner wall surface under normal pressure through a spray nozzle to thoroughly clean the inner wall surface,
A phenol / bisphenol A mixed liquid (mixing weight ratio = 65/35) at 150 ° C. was jetted to thoroughly clean the inner wall surface. (2) Cleaning of the inner wall surface of the packed tower and the surface of the packing material Under normal pressure, 130 ° C. phenol is introduced from the spray nozzle attached to the upper part of the device to clean the inside of the device, and then 130 ° C. phenol is added. Phenol / bisphenol A mixture at 150 ° C (mixing weight ratio = 65 /
According to 35), the wall surface of the device and the surface of the filler were circulated so that they were sufficiently wet. Then, under the conditions of 180 ° C. and 10 Torr, a phenol / bisphenol A mixture (mixing weight ratio = 6
5/35) was distributed. (3) Cleaning of the inner wall surface of the pipe Phenol at 130 ° C was circulated in the pipe for cleaning.
At that time, care was taken so that the gas phase did not exist on the inner wall surface of the tube.
By the above cleaning, it was confirmed that the amount of oxygen adhering to the inner wall surface of the melting device, the inner wall surface of the packed column and the surface of the packing material, and the inner wall surface of the pipe was 5 mmol or less per 1 m ^{2 of} surface area.

Next, a purified crystal adduct (melted) Phenol was removed from the colored APHA: 5) by evaporation to separate and recover bisphenol A, and the mixed vapor obtained from the top of the second packed column was cooled and condensed. The operating conditions of the melting device, the first packed tower, the second packed tower and the cooling condenser system in the above are as follows. (Melting apparatus) Temperature: 130 ° C. Pressure: Normal pressure Atmospheric oxygen concentration: 0.0005 vol% (first packed tower) Temperature: 170 ° C. Pressure: 10 Torr Oxygen concentration in steam atmosphere: 0.0015 vol% (second packed tower) Temperature: 180 ° C. Pressure: 10 torr Steam supply: 0.08 kg per 1 kg of molten liquid Oxygen concentration in steam atmosphere: 0.0002 vol% (operating condition of the first cooler in FIG. 7) (1) Cooling from line 103 to 101 Stripping gas introduced into vessel 1 Pressure: 10 torr Temperature: 180 ° C. Composition: Bisphenol A 25 wt%, phenol 25 w
t%, steam 50 wt% (2) First cooling medium (phenol) introduced from line 105 Temperature: 50 ° C. Cooling medium / stripping gas weight ratio: 6 (3) Bisphenol A from stripping gas in cooler 101 Recovery rate: 100%

(Operation condition of the second cooler in FIG. 7) (1) Uncondensed gas introduced into the second cooler through the line 108 Pressure: 10 Torr Temperature: 51 ° C. Composition: Phenol 65 wt%, Steam 35 wt% ( 2) Second cooling medium (phenol aqueous solution) introduced into the second cooler 102 from the line 109 Temperature: 9 ° C. Cooling medium / uncondensed gas weight ratio: 190 (3) Phenol and uncondensed gas in the cooler 102 Steam recovery rates Phenol recovery rate: 100% Steam recovery rate: 100%

(VII) Dephenolization Step of Crystal Adduct Melt (Experiment I) Bisphenol A / phenol crystal adduct having a melting color of APHA5 under substantially neutral conditions (pH 5.05) was purified with purified phenol. Partially diluted,
It was heated to 130 ° C. to obtain a phenol solution containing 30% by weight of bisphenol A. This phenol solution was used as a raw material liquid and treated using the evaporator system shown in FIG. Next, the main operating conditions of the system shown in FIG. 9 and the component composition of the liquid passing through the main lines will be shown below. (1) First evaporator 201 (i) External heater temperature: 170 ° C. (ii) Internal pressure: 20 Torr (iii) Oxygen concentration in atmosphere: 0.0010 vol% (2) Second evaporator 202 (i) External heater Temperature: 180 ° C. (ii) Internal pressure: 10 Torr (iii) Oxygen concentration in the atmosphere: 0.0030 vol% (3) Third evaporator 203 (i) External heater temperature: 180 ° C. (ii) Internal pressure: 10 Torr ( iii) Oxygen concentration in atmosphere: 0.0030 vol% (4) Bisphenol A through line 216 (i) Phenol content: 29 wtppm (ii) Melt color: APHA15 (5) Steam supply amount through line 215: Line 21
0.04 parts by weight per 1 part by weight of bisphenol A passing 4

(Experiment II) An experiment was conducted in the same manner as in Experiment A, except that 20 wtppm of the additive shown in Table 2 was added to the phenol solution containing bisphenol A as a raw material. Through this experiment, high-purity bisphenol A (APHA: 10, phenol content: 27 wtppm) was obtained through line 16. Next, this bisphenol A was subjected to a thermal stability test (test A) in which the bisphenol A was heated and held at 175 ° C. for 0 hours or 2 hours in an air atmosphere, and the air was heated to 175 ° C.
Was subjected to an accelerated thermal stability test (test B) of 2.0 hours in which the hue at that time was evaluated. The results are shown in Table 2.

[0089]

[Table 2]

[0090]

EFFECTS OF THE INVENTION According to the present invention, the acetone solution is separated from the phenol solution containing bisphenol A and the phenol in the separation step, and the acetone is separated in the reaction step. It can be used effectively. Further, in the present invention,
Since it includes a step of purifying the mother liquor separated from the crystallization product and circulating it in the reaction system, it is possible to prevent the accumulation of by-products and impurities in the reaction system and obtain bisphenol A with high purity and good hue. You can Further, in the present invention, a high-quality bisphenol A can be efficiently and economically produced because it comprises a series of steps in which specific steps are organically combined.

[Brief description of drawings]

FIG. 1 shows a process chart for producing bisphenol A according to the present invention.

FIG. 2 shows a distillation process flow diagram for one example for separating the reaction product of acetone and phenol into specific components.

FIG. 3 shows a distillation treatment system diagram for another example for separating a reaction product of acetone and phenol into specific components.

FIG. 4 shows a crystallization system diagram for one example of a crystallization process of a phenol solution containing bisphenol A.

FIG. 5: Method 1 for treating mother liquor separated from crystallization product
A processing diagram for one example is shown.

FIG. 6 is an explanatory diagram in which a heat treatment device and a retention tank are attached to the reactive distillation column.

FIG. 7 shows a system diagram of a method of condensing a mixed vapor of steam and phenol.

FIG. 8 is a system diagram when a one-column cooling device including a first cooler and a second cooler is used in the method for condensing a mixed vapor of steam and phenol.

FIG. 9 shows a systematic diagram for a method of performing a dephenoling step using a thin film evaporator.

[Explanation of symbols]

 1 Reaction Process 2 Separation Process 3 Crystallization Process 4 Crystallized Product Separation Process 5 Liquefaction Process 6 Dephenolation Process 7 Granulation Process 8 Distillation Process 9 Heating Process (Reaction Tank) 10 Reduced Pressure Recovery Process (Decompressed Evaporation Tower) 31, 32 , 33, 34 Distillation tower 35 Strong acid ion exchange resin treatment device 36, 37 Standing tank 55 Outer cylinder 56 Inner cylinder 57 Microcrystalline adduct dissolution tank 101, 102 Cooler R Strong acid ion exchange resin tower

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Akio Shindo 2-12-1, Tsurumi Chuo, Tsurumi-ku, Yokohama-shi, Kanagawa Chiyo Tadaka Construction Co., Ltd. (72) Nobuyuki Suda Tsurumi-chu, Tsurumi-ku, Yokohama-shi, Kanagawa 2-12-1 Chiyo Tako Construction Co., Ltd. (72) Inventor Makoto Nomura 2-12-1 Tsurumi Chuo, Tsurumi-ku, Yokohama-shi, Kanagawa Chiyo Tako Construction Co., Ltd.

Claims (7)

[Claims] 1. A reaction step in which acetone and excess phenol are reacted in the presence of an acid catalyst to produce bisphenol A, and the reaction product obtained from the reaction step is mixed with acetone, water, and phenol. A separation step of separating into a phenol solution containing bisphenol A, a crystallization step of precipitating a crystal adduct of bisphenol A and phenol from the phenol solution containing bisphenol A, and a crystallization product obtained in the crystallization step Crystallization product separation step for separating crystal adduct and mother liquor, crystal adduct liquefaction step for liquefying crystal adduct obtained in the crystallization product separation step, and bisphenol A obtained in the crystal adduct liquefaction step
A phenol circulation step of removing phenol from a phenol solution containing, further, an acetone circulation step of circulating acetone separated from the separation step in the reaction step,
A phenol circulation step in which at least a part of the phenol obtained in the separation step is circulated as a crystal adduct cleaning liquid in the crystallization product separation step, and a mother liquor circulation in which the mother liquor obtained in the crystallization product separation step is circulated in the reaction step A method for producing bisphenol A, which comprises a step and a mother liquor purification step of purifying a part of the circulating mother liquor, and a purified mother liquor circulation step of circulating the purified mother liquor obtained in the mother liquor purification step into a reaction step. 2. When removing the phenol from the phenol solution containing bisphenol A in the dephenoling step, the phenol solution containing bisphenol A is used under the condition that the oxygen concentration in the atmosphere is 0.005 vol% or less using a thin film evaporator. Evaporated at a temperature of 160-185 ° C. and a pressure of 15-60 Torr to give a phenol content of 1-5.
Phenol evaporation step to obtain wt% bisphenol A and bisphenol A containing phenol obtained in the phenol evaporation step at a temperature of 170-185 ° C. and 15
A first stripping step in which the stripping gas is brought into countercurrent contact with the stripping gas under a pressure of less than or equal to torr and a bisphenol A containing phenol obtained in the first stripping step at a temperature of 170 to 185 ° C. And a second stripping step in which the stripping gas is brought into countercurrent contact with the stripping gas under a pressure of 15 torr or less, and steam is used as the stripping gas in the second stripping step. As stripping gas in the stripping process,
The method of claim 1, wherein a stripping gas consisting of steam containing phenol and bisphenol A obtained in the second stripping step is used. 3. The method according to claim 2, wherein the aliphatic carboxylic acid is added to and mixed with the phenol solution containing bisphenol A. 4. The method according to claim 1, wherein the mother liquor purification step comprises the following steps. (I) a distillation step of introducing the mother liquor into a distillation column and distilling 50 to 90% by weight of the mother liquor introduced into the distillation column to obtain a distillate containing phenol; (ii) the distillation step (i) The bottom liquid of the distillation column obtained in
Heating step of heating to 200 to 350 ° C. in the presence of a basic catalyst, (iii) evaporation of the product obtained in the heating step (ii) under reduced pressure to obtain distillate vapor containing phenol and isopropenylphenol A reduced pressure recovery step, (iv) a quenching step in which the distillate vapor obtained in the reduced pressure recovery step (iii) is brought into contact with the distillate obtained in the distillation step (i) to rapidly cool it. 5. A heating step (ii) and a reduced pressure recovery step (iii)
The method according to claim 4, wherein is carried out simultaneously by using a reaction tower. 6. A part of the bottom liquid of the reaction tower is withdrawn from the reaction tower,
The method according to claim 5, which is heat-treated in the presence of a basic catalyst at a temperature of 200 to 350 ° C. and then circulated in the reaction column. 7. The quenching product obtained in the quenching step (v) is circulated in the reaction step after the quenching material is contacted with a strong acid type ion exchange resin when the quenching material is circulated in the reaction step. Either way.