JP2001316313A - Method for producing crystalline adduct of bisphenol a and phenol for producing high-quality bisphenol a - Google Patents

Abstract

PROBLEM TO BE SOLVED: To reduce a mass of tarry substances discharged from a purging process without deteriorating a quality of a crystalline adduct in a method for producing the crystalline adduct of bisphenol A and phenol. SOLUTION: This method comprises including free acid-removing processes 5, 6 and 7 removing at least one kind of a free acid in a phenol-containing liquid selected from a reactional liquid from a bisphenol A-generating process 1 including a distilling process and a crystallizing process as an aftertreatment and a circulating mother liquor obtained from the crystallizing process 3, keeping a cocentration of the free acid in a distillation-treated product supplied to the crystallizing process 3 within tie range of 0.001-0.5 meq/L and keeping a transporting amount of the circulating mother liquor discharged from the crystallizing process 3 to the purging process 4 in an amount of within the range of 0.5-5 pts.wt. based on the 100 pts.wt. of the total mother liquor discharged from the crystallizing process 3.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for producing a crystalline adduct of bisphenol A and phenol at a reduced cost for producing high quality bisphenol A.

[0002]

2. Description of the Related Art In order to remove impurities contained in bisphenol A, bisphenol A is cooled in a crystallization step to crystallize a crystal adduct composed of bisphenol A and phenol. Separating the crystal adduct and the mother liquor from the mixture of the adduct and the mother liquor, circulating the mother liquor to the bisphenol A generation step, sending a part of the circulating mother liquor to the purging step, where impurities contained in the mother liquor are tar-like. It has been known that the purified mother liquor is converted into a substance and removed, and the obtained purified mother liquor is circulated to a bisphenol A production step (JP-A-5-331088).
It is also known that in the method for producing bisphenol A, the decomposition of bisphenol A and the production of 2,4′-bisphenol A are promoted due to the free acid generated in the main reactor. Since the free acid generated in the main reactor becomes a substance causing the generation of impurities as described above, it is not preferable to circulate the free acid together with the mother liquor in the step of generating bisphenol A. At the same time, the free acid is also removed from the system. However, in order to remove the free acid in the purging step, it is necessary to generate a relatively large amount of tar-like substances in the purging step and discharge the same out of the system, so that the production cost of bisphenol A is inevitable. There was a problem of rising.

[0003]

SUMMARY OF THE INVENTION According to the present invention, a part of a mother liquor obtained in a crystallization step is circulated to a bisphenol A producing step via a purging step, and impurities in the mother liquor are removed in the purging step. Provided is a method for producing a crystal adduct of bisphenol A and phenol which is discharged out of the system as a tar-like substance, wherein a method for reducing the amount of tar-like substance discharged from the purging step without lowering the quality of the crystal adduct is provided. Is the subject.

[0004]

Means for Solving the Problems The present inventors have conducted intensive studies to solve the above-mentioned problems, and as a result, have completed the present invention. That is, according to the present invention, in a method for producing a crystalline adduct of bisphenol A and phenol for producing high-quality bisphenol A, (i) a bisphenol A producing step, and (ii) a reaction obtained in the bisphenol A producing step. A distillation step of distilling the product liquid; and (iii) cooling the distilled product containing bisphenol A obtained in the distillation step to crystallize a crystal adduct composed of bisphenol A and phenol, and separating the crystal adduct from the mother liquor. (Iv) a mother liquor circulation step of circulating the mother liquor obtained in the crystallization step to a bisphenol A production step;
(V) a purging mother liquor transfer step of transferring a part of the circulating mother liquor to a purging step, and (vi) a purging step of converting impurities contained in the mother liquor into tar-like substances and discharging the tar-like substances. (Vii) a purification mother liquor circulation step of transferring the purified mother liquor obtained in the purging step to the bisphenol A production step, and (viii) a supply liquid containing a reaction raw material to be supplied to the bisphenol A production step, and the bisphenol A production step A free acid removal step of removing free acid in at least one phenol-containing liquid selected from a reaction product solution from the reaction product and a circulating mother liquor obtained from the crystallization step, While maintaining the free acid concentration in the distillation product supplied to the crystallization process in the range of 0.001 to 0.5 meq / L, and transferring the circulating mother liquor discharged from the crystallization process to the purge process Of a crystal adduct of bisphenol A and phenol for the production of high-grade bisphenol A, characterized in that the ratio is maintained at 0.5 to 5 parts by weight per 100 parts by weight of the whole mother liquor discharged from the crystallization step. A manufacturing method is provided. In addition, the high-quality bisphenol A referred to in the present specification means bisphenol A which is excellent in hue and hardly causes coloring.

[0005]

BEST MODE FOR CARRYING OUT THE INVENTION The method of the present invention comprises (i) a bisphenol A producing step, (ii) a distillation step of distilling the reaction product obtained in the bisphenol A producing step, and (iii) a distillation step obtained by the distillation step. Cooling the distilled product containing bisphenol A to crystallize a crystalline adduct of bisphenol A and phenol, and separating the crystalline adduct from the mother liquor; and (iv) the crystallization step. A mother liquor circulating step of circulating the mother liquor to the bisphenol A producing step, (v) a mother liquor transferring step for purging processing in which a part of the circulating mother liquor is transferred to a purging step, and (vi) impurities contained in the mother liquor to tar-like substances. A purging step of converting and discharging the tar-like substance; (vii) a purifying mother liquor circulating step of circulating the purified mother liquor obtained in the purging step to the bisphenol A producing step; viii) include the free acid removing step of removing the free acid.

Hereinafter, the present invention will be described with reference to the drawings. FIG. 1 shows an example of a flow sheet for implementing the method of the present invention. In FIG. 1, 1 is bisphenol A
The production step, 2 is a distillation step, 3 is a crystallization step, 4 is a purge step, 5, 6, and 7 are free acid removal steps.

In order to produce a crystal adduct of bisphenol A and phenol according to the flow sheet of FIG. 1, a reaction raw material (mixture of phenol and acetone) is supplied to a bisphenol A production step 1 from a line 11. Also,
In the bisphenol A production step 1, after the impurities are removed as tar-like substances in the purge step 4 through the circulation mother liquor circulated from the crystallization step 3 through the line 31 and the line 12 and the line 27 and the line 12, Is supplied. In the bisphenol A production step 1, a condensation reaction between phenol and acetone is carried out in the presence of a strong acid to produce bisphenol A. The strong acid acts as a catalyst, and a sulfonic acid type cation exchange resin is usually used. The reaction temperature is between 45 and
95 ° C, preferably 55-85 ° C, and the reaction pressure is 1
00 to 510 kPa, preferably normal pressure.

The reaction product liquid comprising bisphenol A, water, unreacted acetone and phenol obtained in the bisphenol A production step 1 is discharged through a line 17 and supplied to a distillation step through a line 20. The distillation step 2
In, a part of water, unreacted acetone and phenol in the reaction product liquid is discharged as a distillate through the line 21. On the other hand, a mixed liquid of bisphenol A and phenol as a distilled product is discharged through the line 22. The mixture of bisphenol A and phenol obtained in the distillation step 2 is supplied to a crystallization step 3, where it is cooled to crystallize a crystal adduct composed of bisphenol A and phenol. This crystal adduct is separated from the mother liquor, washed with phenol, and then heated and melted. Then, it is cooled and crystallized again. In the case of the present invention, this cooling crystallization is carried out in two to three stages, preferably in two stages. The crystallized product is subjected to a solid-liquid separation treatment to be separated into a crystal adduct and a mother liquor. The crystal adduct separated from the mother liquor is discharged through a line 23 and sent to a dephenolization step for removing phenol from the crystal adduct, to be a high-quality product bisphenol A.

On the other hand, most of the mother liquor after the crystal adduct is separated in the crystallization step 3 is circulated to the bisphenol A production step 1 through the lines 24, 28, 31 and 12. Also, part of the mother liquor
4. Transferred to purge step 4 through line 25. Indicating the composition of the mother liquor discharged through said line 24:
Bisphenol A 8-12%, phenol 75-90%
And the impurity is 5 to 15%. In this case, the impurities include free acids, polyphenols such as trisphenol, chroman compounds, and the like.

The details of the purging step 4 are as follows. The purge step 4 includes a phenol distillation tower, a reaction tower having a reaction tank and a reduced pressure evaporation tower, and a strong acid ion exchange resin tower. The raw mother liquor is sent to a phenol distillation column, where the reactive components are concentrated. Next, the concentrated liquid extracted from the bottom of the phenol distillation column is sent to the reaction tank at the bottom of the reaction column together with the basic catalyst. In the reaction tower, in the reaction tank, polyphenols such as bisphenol and trisphenol contained in the concentrated mother liquor are thermally decomposed by the action of a basic catalyst, converted into isopropenylphenol and phenol, and chroman compounds and the like. A polycondensation reaction of the impurities occurs, and the impurities are converted into high-boiling substances. The distillate vapor containing phenol and isopropenylphenol withdrawn from the top of the reaction column is introduced into a reduced pressure condenser attached to the reaction column, where it mixes with and contacts the distillate introduced from the phenol distillation column. After quenching, it is introduced into a strong acid type ion exchange resin tower. In this strong acid type ion exchange resin tower, bisphenol A is generated by the reaction of isopropenylphenol and phenol contained in the mixture. On the other hand, in the bottom liquid (reaction liquid) discharged from the reaction tower, high-boiling substances (having a higher boiling point than bisphenol A) are concentrated, and coloring substances are concentrated as tar.

The tar-like substance obtained in the purging step is discharged through a line 26. The purified mother liquor after the impurities in the mother liquor were removed as tar-like substances was supplied to line 2
7. Recirculated through line 12 to bisphenol A production step 1.

In the present invention, the concentration of the free acid in the distilled product supplied to the crystallization step 3 through the line 22 is determined as follows:
0.001 to 0.50 meq / L, preferably 0.00
It is defined in the range of 1 to 0.10 meq / L. By subjecting the distilled product having such a free acid concentration to a cooling crystallization treatment in the crystallization step 3, a high-quality crystal adduct substantially containing no free acid is provided. The free acid concentration in the crystal adduct is 0.002 meq / L or less, particularly 0.001 meq, expressed as the free acid concentration in the crystal adduct melt.
/ L or less. The free acid is derived from a strong acid used as a catalyst in the bisphenol A production step.

In order to maintain the concentration of free acid in the distilled product supplied to the crystallization step 3 at 0.001 to 0.5 meq / L, preferably 0.001 to 0.10 meq / L, the free acid is removed. A step is provided where free acid is removed. The free acid removing step can be configured using an adsorbent capable of absorbing and removing the free acid. As such an adsorbent, activated carbon or basic inorganic oxide having no eluting impurities can be used, but a basic anion exchange resin is preferably used. As this weakly basic anion exchange resin,
Conventionally known various ones are used. These include, as weakly basic anion exchange groups, primary amines,
Secondary amines, tertiary amines and the like are included. Examples of those that can be preferably used in the present invention include, for example, "Amberlite" manufactured by Rohm and Haas, "Dowex" manufactured by Dow Chemical Company, and "Diaion" manufactured by Mitsubishi Chemical Corporation. Can be mentioned.

The location of the free acid removing step is as follows:
It is sufficient that the concentration of the free acid in the distilled product supplied to the crystallization step 3 is maintained within the above range, and the phenol-containing liquid containing the free acid at a high concentration, usually at a concentration of 0.5 meq / L or more It should be applied to In the present invention, (i)
(Ii) the feed liquid to bisphenol A production step 1, (ii) the reaction product liquid from bisphenol A production step 1 and (ii)
i) It is preferably applied to at least one phenol-containing liquid selected from the mother liquor circulating from the crystallization step 3 to the bisphenol A generation step 1.

In FIG. 1, free acid removal steps 5, 6, 7
Shows examples applied to the raw material liquid supplied to the bisphenol A production step 1, the reaction product liquid from the bisphenol A production step 1, and the circulating mother liquor, respectively. The free acid removing step can be provided at three places as shown in FIG. 1, but may be provided at two places or one place, and preferably at one place. When one free acid removing step is provided, it is preferable to apply the method to the mother liquor at the outlet of the crystallization step 3. When the free acid removing step is applied to the phenol-containing liquid, the entire phenol-containing liquid to be treated may be treated, or only a part thereof may be treated. The amount of the treatment may be appropriately determined in relation to the concentration of the free acid in the distilled product introduced into the crystallization step.

In the present invention, as described above, the concentration of free acid in the distilled product supplied to the crystallization step 3 is 0.5 m
eq / L or less, and the amount of the mother liquor discharged from the crystallization step 3 to be transferred to the purge step 4 is 0.5 to 5 parts by weight, preferably 1 to 100 parts by weight of the mother liquor.
To 4 parts by weight. In the case of the present invention, in addition to the purging step 4, the free acid in the system is removed in the free acid removing steps 5, 6, and 7, the purging step 4 does not need to be operated for the purpose of removing the free acid. Instead, the operation may be performed for the purpose of removing impurities other than the free acid. as a result,
As described above, even if the amount of the mother liquor transferred to the purge step 4 is reduced, the quality of the crystal adduct discharged from the crystallization step 3 is not impaired. In addition, as a result of reducing the amount of mother liquor transferred to the purging step 4, the amount of tar-like substances discharged from the purging step 4 is also reduced.

[0017]

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

Example 1 A crystalline adduct with bisphenol A was produced according to the flow sheet shown in FIG. The main operating conditions in this case are shown below in relation to FIG. In this case, the free acid removing steps 5 and 6 were omitted, and only the free acid removing step 7 was used. (1) Bisphenol A production step 1 (i) Reaction temperature: 60 ° C. (ii) Reaction pressure: 405 kPa (iii) Catalyst: sulfonic acid type cation exchange resin (trade name “Amberlite 11” manufactured by Rohm and Haas Company)
8-H ") (2) Reaction product solution from bisphenol A production step 1 (line 17) (i) Flow rate: 116.7 kg / h (ii) Component composition Bisphenol A: 18.8% Phenol: 73.6% Water: 1.0% Acetone: 0.8% Free acid: 0.086 meq / L Other impurities: 5.8% (3) Line 21 (i) Flow rate: 17.8 kg / h (ii) Component composition Water: 7.2% Acetone: 5.8% Phenol: 86.1% Other: 0.9%

(4) Line 22 (i) Flow rate: 98.9 kg / h (ii) Component composition Bisphenol A: 22% Phenol: 74% Free acid: 0.101 meq / L Other impurities: 4% (5) Line 23 (i) Crystal adduct flow rate: 22.1 kg / h (ii) Free acid: 0.001 meq / L or less (6) Line 24 (i) Flow rate: 100 kg / h (ii) Component composition Bisphenol A: 7.7% Phenol: 86.3% Free acid: 0.1 meq / L Other impurities: 6%

(7) Line 25 Flow rate: 3.0 kg / h (8) Purge step 4 (i) Reactive distillation column Column bottom temperature: 250 ° C. Pressure: 15.9 kPa (ii) Strong acid type ion exchange resin column Temperature: 53 C. Pressure: 101 kPa (9) Line 26 (i) Tar-like substance flow rate: 0.2 kg / h (10) Line 27 (i) Flow rate: 2.8 kg / h (ii) Component composition Bisphenol A: 8.0% phenol : 89.5% Free acid: 0 meq / L Other impurities: 2.5% (11) Line 29 (i) Flow rate: 7.0 kg / h (ii) Free acid: 0.1 meq / L (12) Removal of free acid Step 7 (i) Adsorbent: an anion exchange resin having a secondary amine group (“Amberlite” manufactured by Rohm and Haas Co.) (ii) Temperature: 50 ° C. (13) Line 30 (i) Free acid : 0.02 meq L (14) line 16 (i) flow rate: 116.7kg / h (ii) free acid: 0.078meq / L

Comparative Example 1 An experiment was conducted in the same manner as in Example 1 except that the free acid removing steps 5, 6, and 7 were not used. In this case, in order to maintain the free acid concentration in the distilled product supplied to the crystallization step at 0.101 meq / L, which is the same as in Example 1,
The mother liquor flow rate to be transferred to the purge step is 10 kg / h,
It was necessary to reduce the amount of tar-like substances to 0.7 kg / h, and the production cost of the crystal adduct was higher than that of Example 1.

[0022]

According to the present invention, it is possible to produce a high-quality crystalline adduct of bisphenol A and phenol substantially free of a free acid necessary for producing high-grade bisphenol A. High-quality bisphenol A can be obtained from this crystal adduct. In the case of the present invention,
Since the amount of mother liquor transferred to the purge step is reduced, the size of the purge step can be reduced, and the amount of tar-like substances discharged from the purge step can also be reduced. Therefore, the amount of the phenol and acetone used as feed materials can be saved because the amount of the tar-like substances discharged to the outside of the system is reduced. As a result, the production cost of bisphenol A can be reduced. it can. Further, in the case of the present invention, it is not necessary to make the free acid concentration in the distilled product supplied to the crystallization step zero, and 0.001 to 0.5 me
Since it is sufficient to keep the ratio in the range of q / L, the load of the free acid removing step can be reduced, and the use ratio of the adsorbent can be reduced. As a result, the free acid removing step can be performed at a reduced cost.

[Brief description of the drawings]

FIG. 1 shows an example of a flow sheet for carrying out the method of the present invention.

[Explanation of symbols]

 1 Bisphenol A production step 2 Distillation step 3 Crystallization step 4 Purge step 5, 6, 7 Free acid removal step

 ──────────────────────────────────────────────────続 き Continuing on the front page (72) Inventor Tsuyoshi Shibuya 2-1-1, Tsurumichuo, Tsurumi-ku, Yokohama-shi, Kanagawa Prefecture Inside Chiyoda Kako Construction Co., Ltd. (72) Susumu Yamamoto Susumu Yamamoto Tsurumi-chuo, Tsurumi-ku, Yokohama-shi, Kanagawa No. 12-1 Chiyoda Chemical Construction Co., Ltd. (72) Inventor Hiroaki Nishijima 2-1-1 Tsurumi Chuo, Tsurumi-ku, Yokohama-shi, Kanagawa Prefecture F-term in Chiyoda Chemical Construction Co., Ltd. 4H006 AA02 AC25 AD11 AD15 AD17 AD32 AD33 BD42 BD52 BD60 BD84 FC52 FE13

Claims (4)

[Claims] 1. A method for producing a crystalline adduct of bisphenol A and phenol, comprising: (i) bisphenol A
A production step, (ii) a distillation step of distilling the reaction product liquid obtained in the bisphenol A production step, and (iii) a distillation treatment product containing bisphenol A obtained in the distillation step is cooled to produce A crystallization step of crystallizing the resulting crystal adduct and separating the crystal adduct from the mother liquor; (iv) a mother liquor circulating step of circulating the mother liquor obtained in the crystallization step to a bisphenol A producing step;
(V) a purging mother liquor transfer step of transferring a part of the circulating mother liquor to a purging step, and (vi) a purging step of converting impurities contained in the mother liquor into tar-like substances and discharging the tar-like substances. (Vii) a purification mother liquor circulation step of transferring the purified mother liquor obtained in the purging step to the bisphenol A production step, and (viii) a supply liquid containing a reaction raw material to be supplied to the bisphenol A production step, and the bisphenol A production step A free acid removal step of removing free acid in at least one phenol-containing liquid selected from a reaction product solution from the reaction product and a circulating mother liquor obtained from the crystallization step, While maintaining the free acid concentration in the distillation product supplied to the crystallization process in the range of 0.001 to 0.5 meq / L, and transferring the circulating mother liquor discharged from the crystallization process to the purge process Of a crystalline adduct of bisphenol A and phenol for the production of high-grade bisphenol A, characterized in that the ratio is 0.5 to 5 parts by weight per 100 parts by weight of the total mother liquor discharged from the crystallization step. Production method. 2. The method according to claim 1, wherein, in the free acid removing step, the phenol-containing liquid is brought into contact with an adsorbent to adsorb the free acid contained in the phenol-containing liquid to the adsorbent. 3. The method of claim 2 wherein said adsorbent comprises a weakly basic anion exchange resin. 4. The method according to claim 1, wherein the number of crystallization stages in the crystallization step is two.