JP2006036668A - Method and apparatus for producing bisphenol a - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To reduce a chemical recycling load and obtain relatively high purity bisphenol A with respect to a reclaimed product. <P>SOLUTION: A method for producing bisphenol A comprises a BPA (bisphenol A) reaction step 1, a concentration step 2, crystallization steps 6A and 6B, production steps 7, 8, and 9 of obtaining bisphenol A, a separation step SR of separating the solution from the concentration step 2 into a solution containing unreacted phenol, a solution containing unreacted acetone, and a solution containing water, a decomposition step 51 of decomposing waste polycarbonate, a BPA synthesis step 52 of synthesizing bisphenol A from a solution containing phenol after decomposition, and a synthesis solution feeding step of feeding a solution containing the synthesized bisphenol A to the concentration step 2. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a method and an apparatus for producing bisphenol A including a step of recovering bisphenol A in waste polycarbonate.

  Bisphenol A [2,2-bis (4′-hydroxyphenyl) propane] is used as a raw material for polycarbonate and epoxy resin.

  In order to produce bisphenol A, it is known to react acetone with excess phenol in the presence of an (acid) catalyst. Further, in order to separate and recover high-purity bisphenol A from this reaction product, the reaction product was crystallized to precipitate a crystal adduct of bisphenol A and phenol (hereinafter simply referred to as a crystal adduct). It is also known to remove phenol from a crystalline adduct (Japanese Patent Publication Nos. 36-23335 and 52-42790). At present, the present inventors have found that the method according to Japanese Patent Laid-Open No. 7-25798 is one method that is practically effective.

  Polycarbonate for applications such as compact disc (CD), CD-R, DVD (digital video disc), and the like is particularly required to be colourless, colorless and highly pure bisphenol A.

  However, the reaction product in the reaction step includes 2- (2'-hydroxyphenyl) -2- (4'-hydroxyphenyl) -propane, which is an isomer of bisphenol A in addition to phenol and bisphenol A. Contains by-products such as bisphenol compounds such as 2,4'-bisphenol A (hereinafter simply referred to as 2,4'-bisphenol A), trisphenol, high molecular weight polyphenol compounds, chroman compounds, etc., and contains very small amounts of colored impurities and coloring impurities. It is. And since the reaction product contains the colored impurity and the impurity which is easy to color, it is the colored liquid which gives a high coloring density | concentration by heating. Therefore, in order to obtain high purity bisphenol A, it is necessary to remove the by-products, coloring impurities, and coloring impurities.

  On the other hand, polycarbonate resin made from bisphenol A is used in large quantities for compact discs (CD), CD-Rs, DVDs (digital video discs), etc., and disposal of used CDs is a problem. Attempts have been made to recycle such disposal instead of discarding from the viewpoint of environmental protection.

  As a recycling method of waste plastic, there is a chemical recycling method in which waste plastic is depolymerized into a monomer or reused as a useful chemical raw material. Methods that are directed to chemical recycling methods for waste polycarbonate include methods such as JP-A No. 2001-160243, JP-A No. 2001-270961, JP-A No. 2001-302573, JP-A No. 2002-212335, and JP-A No. 2003-147121. Are known.

  However, this kind of waste polycarbonate chemical recycling method is reused as a useful chemical raw material, but assumes an independent recycling process in which only waste plastics are limited to raw materials, and bisphenol A using phenol and acetone as raw materials. It is not incorporated into the manufacturing process.

  Further, after separating the reaction product from the reaction product into a liquid containing bisphenol A and a liquid containing unreacted phenol, unreacted acetone and water, the latter liquid is mixed with a liquid containing unreacted phenol and unreacted acetone. Separation into a liquid containing water and a liquid containing water is usually carried out by distillation. However, since it is difficult to separate by distillation using only these components, an azeotropic agent is added as a third component in an azeotropic state. It is known to carry out distillation (Japanese Patent No. 2796557).

In this case, it is desirable to circulate the azeotropic agent. However, when the waste polycarbonate chemical recycling method is incorporated into the production process of bisphenol A, for example, the solvent in the decomposition process of waste polycarbonate such as cyclohexanol accumulates as impurities, which hinders the production of high-purity bisphenol A.
Japanese Unexamined Patent Publication No. 7-25798 Japanese Patent No. 2796557

  The main object of the present invention is to incorporate a decomposition process for decomposing waste polycarbonate into the production process of bisphenol A, thereby reducing the burden of chemical recycling, and using bisphenol A of relatively high purity for the recycled product. There is to get. Another problem is to prevent the accumulation of impurities such as cyclohexanol as a solvent during chemical recycling and facilitate the production of high purity bisphenol A.

The present invention that has solved the above problems is as follows.
<Invention of Claim 1>
The manufacturing method of bisphenol A characterized by including the process of the following description.
(1) a reaction step of reacting acetone with an excess amount of phenol in the presence of a catalyst to produce bisphenol A;
(2) A concentration step for separating the reaction product from the reaction step into a phenol solution containing bisphenol A and a liquid containing unreacted phenol, unreacted acetone and water,
(3) a crystallization step of precipitating a crystal adduct of bisphenol A and phenol from a phenol solution containing bisphenol A;
(4) A commercialization process for obtaining bisphenol A from the crystallized product in the crystallization process,
(5) a low boiling point component recovery step for separating the liquid containing unreacted phenol, unreacted acetone and water from the concentration step into a liquid containing unreacted acetone and a liquid containing unreacted phenol and water; A phenol recovery step for separating the liquid containing the unreacted phenol and water from the boiling component recovery step into a liquid containing the unreacted phenol and a liquid containing water using an azeotropic agent, A separation step having a liquid-liquid separation step of separating water from a liquid containing water,
(6) Decomposition process for decomposing waste polycarbonate,
(7) Take at least one of the following steps (A) and (B).
(A) A decomposition liquid supply step for supplying the liquid decomposed in the decomposition step to the reaction step.
(B) A decomposition solution supply step for supplying the solution decomposed in the decomposition step to a BPA synthesis step for synthesizing bisphenol A, and a synthetic solution supply for supplying a synthesis solution containing bisphenol A obtained by the BPA synthesis step to the concentration step Process.

<Invention of Claim 2>
The method for producing bisphenol A according to claim 1, further comprising a pulverization step of pulverizing waste polycarbonate prior to the decomposition step, wherein the decomposition step decomposes the pulverized product from the pulverization step.

<Invention of Claim 3>
Recovering at least a part of the liquid containing the azeotropic agent used in the separation step, separating impurities contained in the decomposition liquid or the synthesis liquid from the azeotropic agent, and separating the azeotropic agent, The manufacturing method of the bisphenol A of any one of Claims 1-2 including the azeotropic agent collection | recovery process which aims at reuse in a isolation | separation process.

<Invention of Claim 4>
The azeotropic agent recovery step: recovers at least a part of the liquid containing the azeotropic agent after separating the water from the liquid-liquid separation step, and azeotropes with impurities contained in the decomposition liquid or the synthesis liquid. The method for producing bisphenol A according to claim 3, wherein the azeotropic agent is separated from the agent, and the separated azeotropic agent is returned to the phenol recovery step for reuse.

<Invention of Claim 5>
The method for producing bisphenol A according to any one of claims 3 to 4, wherein the azeotropic agent recovery step separates the azeotropic agent, the light impurities 1, and the light impurities 2.

<Invention of Claim 6>
The production of bisphenol A according to any one of claims 3 to 5, wherein the azeotropic agent is one or more selected from the group consisting of benzene, alkylbenzenes, cyclohexanol, cyclohexanone, cyclohexene, and cyclohexane. Method.

<Invention of Claim 7>
The method for producing bisphenol A according to any one of claims 3 to 6, wherein the decomposition step of decomposing the waste polycarbonate uses at least one of phenol and an azeotropic agent used in the separation step as a solvent.

<Invention of Claim 8>
The method for producing bisphenol A according to claim 7, wherein when the phenol is used as the solvent in the decomposition step, the azeotropic agent is not recovered in the separation step.

<Invention of Claim 9>
An apparatus for producing bisphenol A, comprising the following means.
(1) Reaction means for reacting acetone with an excess amount of phenol in the presence of a catalyst to produce bisphenol A,
(2) A concentration means for separating the reaction product from the reaction means into a phenol solution containing bisphenol A and a liquid containing unreacted phenol, unreacted acetone and water,
(3) A crystallization means for precipitating a crystal adduct of bisphenol A and phenol from a phenol solution containing bisphenol A,
(4) Productization means for obtaining bisphenol A from the crystallized product in the crystallization means,
(5) Low boiling point component recovery means for separating the liquid containing unreacted phenol, unreacted acetone and water from the concentration means into a liquid containing unreacted acetone and a liquid containing unreacted phenol and water; Phenol recovery means for separating the liquid containing unreacted phenol and water from the boiling point component recovery means into a liquid containing unreacted phenol and a liquid containing water, and water from the liquid containing the water from the phenol recovery means Separating means having a liquid-liquid separating means for separating,
(6) Decomposing means for decomposing waste polycarbonate,
(7) It has at least one means of the following (A) and (B).
(A) Decomposed liquid supply means for supplying the liquid decomposed by the decomposing means to the reaction step.
(B) A decomposition liquid supply means for supplying the liquid decomposed by the decomposition means to a BPA synthesis process for synthesizing bisphenol A, and a synthetic liquid supply for supplying a synthesis liquid containing bisphenol A obtained by the BPA synthesis process to the concentration process means.

<Invention of Claim 10>
At least a part of the liquid containing the azeotropic agent used in the separation means is recovered, impurities contained in the decomposition liquid or the synthesis liquid are separated from the azeotropic agent, and the separated azeotropic agent is The apparatus for producing bisphenol A according to claim 9, further comprising an azeotropic agent recovery means for reusing in the separation means.

  In the present invention, a decomposition process for decomposing waste polycarbonate is incorporated into the production process of bisphenol A. If this decomposition process is used as it is, a high-purity recycled product cannot be obtained. Therefore, if an attempt is made to obtain a high-purity product, an additional process such as a process for removing impurities is required, and many additional facilities are required for the additional process. This requires not only high construction costs but also high purity. On the other hand, by incorporating a decomposition process for decomposing waste polycarbonate into a liquid containing phenol into the production process of bisphenol A, the liquid after the decomposition process can be used for impurities in the existing (or newly established) bisphenol A production process. As a result, compared with the case where chemical recycling is carried out independently, the burden of chemical recycling is reduced, and a relatively high purity bisphenol A is obtained for the recycled product derived from waste polycarbonate. be able to.

  On the other hand, when azeotropic distillation is used when separating a liquid containing unreacted phenol, unreacted acetone and water into a liquid containing unreacted phenol, a liquid containing unreacted acetone, and a liquid containing water, Impurities such as cyclohexanol used as a solvent during chemical recycling of waste polycarbonate by installing an azeotropic agent recovery process that removes impurities outside the system when recovering the azeotropic agent for the circulation of the agent Accumulation of bisphenol A can be facilitated.

Next, the present invention will be clarified while showing some best embodiments for carrying out the present invention.
The embodiment is based on the methods disclosed in Japanese Patent Application Laid-Open Nos. 7-25798 and 2796557.

Here, prior to the description of the steps along the drawings, the components of the system will be described in advance.
[S]: “Light impurities 0” (boiling point lower than acetone (56 ° C.) and boiling point higher than acetone but mixed in acetone)
This indicates a substance or cocatalyst that is present in a trace amount in the raw material and is mixed and accumulated in recovered acetone due to the formation of an azeotrope with acetone.
Example: Methanol

[L]: “Light impurity 1” (boiling point higher than acetone (56 ° C.) and lower than azeotropic agent (136 ° C. in the case of ethylbenzene))
In the case of using an azeotropic agent in the conventional “acetone-water-phenol” separation, it indicates that the azeotropic agent accumulates in the acetone circulation line or may accumulate in the azeotropic agent circulation line.
Example: cyclohexene, benzene, toluene

[M]: “Light impurities 2” (boiling point higher than azeotropic agent and lower than phenol (182 ° C.))
Since the boiling point is higher than that of the azeotropic agent, it accumulates in the azeotropic agent circulation line.
Example: cyclohexanol, cyclohexanone

[H]: “Heavy impurity 1” (having less than 2 benzene rings)
Since it has a boiling point higher than that of phenol, it flows out to the crystallization step in the first distillation step. However, the whole is not clearly separated, and a part is mixed in the liquid side having a low boiling point and accompanies the light impurities 2 and accumulates in the azeotropic agent circulation line. Some of this group has the potential to become product BPA through a secondary reaction step.
Examples: Cresol, ethylphenol, isopropylphenol, isopropenylphenol, t-butylphenol

[T]: “Heavy impurity 2” (having two or more benzene rings)
It is an isomer or polymer of BPA. These are thermally decomposed into heavy impurities 1 and then re-synthesized into BPA. However, not all of them are decomposed and further polymerized to become macromolecules at the same time. Since this product cannot be processed, it is discharged as tar, burned if necessary, and recovered as energy.
Examples: 2,4'-bisphenol, diphenyl carbonate, chroman, trisphenol

  FIG. 1 is a process diagram for producing bisphenol A according to the present invention. In FIG. 1, 1 is a BPA (bisphenol A) reaction step, 2 is a concentration step, 3 is a low boiling point component recovery step, 4 is a phenol recovery step, 5 is a phenol purification step, 6 (6A and 6B) is a crystallization step, 7 (7A and 7B) is a solid-liquid separation process, 8 is a phenol separation process, 9 is a granulation process, 10 is a distillation process, 11 is a heating and decompression recovery process, and 12 is a phenol evaporator. Further, 40 indicates a liquid-liquid separation step, 41 indicates an azeotropic agent recovery step, and the low boiling point component recovery step 3, the phenol recovery step 4, the liquid-liquid separation step 40, and the azeotropic agent recovery step 41 constitute a separation step SR. is doing. In addition, the solid-liquid separation process 7 (7A and 7B), the phenol separation process 8 and the granulation process 9 constitute a product production process.

  In the BPA reaction step 1, a reaction between acetone (raw material acetone and recovered acetone) and an excess amount of phenol (raw material phenol and phenol in the circulating mother liquor) is performed in the presence of a catalyst (for example, an acid catalyst). A is generated. As the acid catalyst, a mineral acid such as hydrochloric acid or sulfuric acid, or a strong acid ion exchange resin having a sulfonic acid group is used, but a strong acid ion exchange resin is preferably used. For example, the amount of phenol used is a reaction temperature of 45 to 90 ° C. at a rate of 8 to 20 mol with respect to 1 mol of acetone.

  The reaction product obtained in the BPA reaction step 1 includes bisphenol A, which is the target product, bisphenol compounds such as 2,4′-bisphenol A, which is an isomer of bisphenol A, trisphenol compounds, and high molecular weight polyphenol compounds. Further, it contains by-products such as a chroman compound and water, and further contains coloring impurities and coloring impurities. This reaction product is introduced into the concentration step 2 and then into the separation step SR.

  The separation step SR can employ any separation step as long as it is configured to separate the reaction product into the specific components described above, but in the embodiment, the distillation step includes a plurality of distillation columns. It is composed of

  Each step will be described in order below. In the concentration step 2 and the separation step SR, the reaction product obtained in the BPA reaction step 1 is subjected to separation treatment, and mainly a phenol solution containing acetone, water, phenol and bisphenol A. It is the process of separating each. In the concentration step 2, the phenol solution containing bisphenol A is discharged and introduced into the phenol evaporator 12 through the line 203. In the separation step SR, recovered acetone (including the cocatalyst, if any) is circulated through the line 204 to the BPA reaction step 1, waste water is discharged through the line 303, and a liquid containing phenol is fed into the line 207. And is introduced into the phenol purification step 5.

  The concentration step 2 and the separation step SR will be further described. The reaction product obtained in the BPA reaction step 1 in which phenol and acetone are reacted is introduced into the first distillation column constituting the concentration step 2, and this In one distillation column, a column bottom (P, H, B) containing unreacted phenol, bisphenol A and heavy impurities, and a column top containing unreacted phenol, unreacted acetone, promoter, water and light impurities ( S, A, L, W, M, P).

  The top product (S, A, L, W, M, P) is introduced into the second distillation column constituting the low boiling point component recovery step 3 together with water added through the line 202, if necessary, through the line 105, After the bottom (P, H, B) (phenol solution containing bisphenol A) obtained in the first distillation column constituting the concentration step 2 is sent to the phenol evaporator 12, excess phenol is removed. The raw material for crystallization is sent to the crystallization step 6A.

  As shown in the drawing, while a part (S, A) of the column top is passed through the line 201, the raw material acetone is supplied from the line 102B, and the promoter is supplied to the appropriate stage of the low boiling point component recovery step 3 through the line 104. Can be added.

  Here, some explanation is added about a co-catalyst. Conventionally, as a method for producing bisphenols, a compound containing sulfur as a cocatalyst is often used in order to improve the activity of the catalyst. For example, US Pat. No. 2,775,620 discloses reacting phenol and dimethyl ketone in the presence of an acid catalyst composed of a strong mineral acid such as hydrogen chloride and methyl mercaptan as a cocatalyst. Discloses a process for producing 2,2-di- (hydroxyphenyl) propane. U.S. Pat.No. 2,468,982 describes the presence of an acidic condensing agent such as sulfuric acid, hydrogen chloride, aluminum chloride and the like and a catalyst such as mercaptoacetic acid and mercaptopropionic acid substituted with a mercapto group. A method for producing bisphenol by reacting phenol and ketone is disclosed. U.S. Pat. No. 2,623,908 discloses 4,4′-isopropylidenephenol by reacting phenol with acetone in the presence of an acidic condensing agent such as hydrogen chloride, hydrochloric acid, hydrogen bromide or the like. Is disclosed, and it is described that when a volatile sulfur-containing catalyst such as mercaptocarboxylic acid is present together with the acidic condensing agent, the condensation rate of phenol and acetone is increased. Also in the present invention, it is desirable to use a cocatalyst. As the alkyl mercaptan used as the cocatalyst in the present invention, a mercaptan having an alkyl group having 1 to 10 carbon atoms is suitable. Specific examples include methyl mercaptan, ethyl mercaptan, propyl mercaptan, octyl mercaptan, cyclohexyl mercaptan, and the like. Of these, ethyl mercaptan is particularly preferred. In addition, these alkyl mercaptans may be used independently and may be used in combination of 2 or more type.

  From the top of the second distillation column constituting the low boiling point component recovery step 3, acetone (including a cocatalyst, if any) is obtained as the top product. This recovered acetone passes through the line 204. And recycled to the BPA reaction step 1. On the other hand, the bottom of the second distillation column is supplied to the phenol recovery step 4 including the third distillation column through the line 205. The content of acetone in the bottom of the second distillation column is 5% by weight or less, preferably 0%.

  In the third distillation column constituting the phenol recovery step 4, for example, a distillation treatment is performed in the presence of an oily azeotropic agent (for example, ethylbenzene), and the phenol is separated into a liquid containing the azeotropic agent and water.

  Various oily azeotropic agents are conceivable. In this case, in order to separate phenol and water, 1) an azeotropic mixture with water is formed, and 2) the mixture forms a two-liquid phase. It must be a substance that has the properties of 3) no chemical reaction with phenol and 4) no azeotrope with phenol. When the oily azeotropic agent is a pure substance, generally a hydrocarbon oil having a boiling point of 80 to 180 ° C, preferably 80 to 160 ° C is used. Specific examples of the azeotropic agent include alkylbenzenes such as benzene, toluene and ethylbenzene, cyclohexanol, cyclohexane, cyclohexene and cyclohexanone. The azeotropic agent may be a pure substance, but may be a mixture of two or more kinds of substances.

  From the top of the third distillation column constituting the phenol recovery step 4, a top product composed of a liquid containing an azeotropic agent and water is obtained. This is supplied to the liquid-liquid separation step 40 through a line 206, where it is separated into water and a liquid containing an azeotropic agent.

  When phenol is selected as the solvent in the decomposition step of decomposing waste polycarbonate described later, and when the same substance as the azeotropic agent is selected, impurities do not accumulate, so it is necessary to pass through the azeotropic agent recovery step 41 May disappear. In this case, the entire amount of the liquid containing the separated azeotropic agent is circulated to the phenol recovery step 4 through the lines 208A, 209A and 208B.

  On the other hand, when another component is selected as a solvent in the decomposition step of decomposing waste polycarbonate, at least a part of the separated liquid containing the azeotropic agent passes through the line 209B, and in the azeotropic agent recovery step 41, The azeotropic agent is separated into the boiling agent, the light impurity 1 and the light impurity 2, and the separated azeotropic agent is returned to the phenol recovery step 4 through the line 209C and reused. Light impurities 1 and 2 are discharged out of the system for incineration. In this case, the entire amount of the liquid containing the separated azeotropic agent can be passed through the line 209B, and the remainder can be bypassed through the line 209A while being partly guided to the azeotropic agent recovery step 41 through the line 209B. .

  The bottom of the third distillation column constituting the phenol recovery step 4 is passed through a strong acid ion exchange resin treatment device (not shown) as necessary, or directly through the line 207 as shown in the figure, as a phenol purification step. 5 is introduced.

  Here, in a strong acid ion exchange resin treatment apparatus that can be installed as necessary, the strong acid ion exchange resin serves as a catalyst to condense colored impurities contained in the bottom of the column, colored impurity precursors, etc. The organic impurities undergo a condensation reaction and are converted into tar-like high-boiling substances. In this case, examples of the condensable impurity include benzofuran. As the strong acid type ion exchange resin, a gel type having a sulfone group is used, and such a strong acid type ion exchange resin is well known. For example, amberlite and amber list that can be obtained from Rohm and Haas, diamond ion that can be obtained from Mitsubishi Chemical Corporation, and the like can be preferably used. The treatment of the bottom of the tower using the strong acid ion exchange resin can be carried out by circulating the tower bottom through a packed tower containing the strong acid ion exchange resin or by placing the tower bottom in a stirring tank containing the strong acid ion exchange resin. It can be carried out by a method of adding and stirring. The treatment temperature is 45 to 150, preferably 50 to 100 ° C. The contact time between the strong acid ion exchange resin and the bottom of the tower is 5 to 200 minutes, preferably about 15 to 60 minutes.

  The first crystallization step 6A is a step of precipitating a crystal adduct by cooling the solution containing bisphenol A obtained in the separation step, particularly the concentration step 2 as described above. In this case, the crystallization temperature is 35 to 80 ° C, preferably 45 to 70 ° C. The crystallization product (crystal adduct slurry) obtained in the first crystallization step 6A is introduced into the first solid-liquid separation step 7A.

  In the first solid-liquid separation step 7A, the crystal adduct slurry is separated into a crystal adduct and a mother liquor, and the crystal adduct uses the purified phenol extracted through the line 226 and the mother liquor in the second solid-liquid separation step 7B. A cleaning process is performed using the cleaning liquid. Then, the separated mother liquor is extracted from the first solid-liquid separation step 7A through the line 211 together with the washed phenol as necessary, and is introduced into the distillation step 10 through the line 212. In this case, at least a part of the mother liquor, usually 1 to 40% by weight, is circulated through the line 213 to the first crystallization step 6A.

  In the first solid-liquid separation step 7A, when the crystal adduct slurry is filtered to separate the crystal adduct from the mother liquor, at least part of the microcrystalline adduct component having a particle size of 100 μm or less among the crystal adducts contained in the slurry. To the filtrate (mother liquor) side to obtain a coarse crystal adduct in which the proportion of the microcrystalline adduct component having a particle size of 100 μm or less is 20 wt% or less, preferably 15 wt% or less. In this case, in order to transfer the microcrystalline adduct component to the filtrate side, it can be performed by selecting a filter (filter medium) or selecting a filtering operation condition. As the filter, a filter having a mesh size of 100 to 300 μm, preferably 150 to 250 μm is generally used. In addition, when the microcrystalline adduct component is transferred to the filtrate side depending on the filtration operation conditions, 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. Can do.

  The crystal adduct obtained as described above can be further improved in quality by washing with purified phenol extracted through the line 226. The crystal adduct can be washed with purified phenol as long as the crystal adduct can be sufficiently brought into contact with the purified phenol. This washing process is performed by, for example, 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. The crystal adduct on which a small amount of mother liquor discharged from the solid-liquid separation apparatus adheres can also be washed with purified phenol in another stirring tank. The proportion of purified phenol used relative to the crystalline adduct is 50 parts by weight or more, preferably 100 parts by weight or more with respect to 100 parts by weight of the crystal adduct.

  The crystal adduct washed with purified phenol is a crystal having an equimolar composition of bisphenol A and phenol, but is dissolved by a condensed liquid containing vapor generated by decompression in each crystallization step, Impurities in the crystal are also dispersed in the solvent, and in this state, the impurities are introduced into the second crystallization step 6B through the line 220 and subjected to a recrystallization operation. This crystallization is performed in a higher purity state.

  After recrystallization, the crystal adduct is introduced into the next second solid-liquid separation step 7B as described above. In the second solid-liquid separation step 7B, the raw material phenol from the line 101B can be used for washing. After the crystal adduct obtained in the second solid-liquid separation step 7B is separated from the mother liquor, it is introduced into the phenol separation step 8 through the line 221 and heated to its decomposition temperature. The separated mother liquor is used for at least one of the cleaning liquid in the first solid-liquid separation step 7A and the solvent in the second crystallization step 6B.

  In the above description, the phenol separation step 8 is entered immediately after the second solid-liquid separation step 7B. However, the present invention is not limited to this, and the steps of recrystallization and solid-liquid separation are performed again. It may be repeated.

  Phenol can be removed from the crystal adduct by a conventionally known method such as distillation, extraction, steam stripping or the like. The product bisphenol A can be granulated into an appropriate shape by the granulation step 9 and commercialized, and is carried out of the system through the line 301.

  According to the filtration of the crystal adduct slurry and the cleaning treatment of the crystal adduct, it is possible to efficiently remove highly adsorbing impurities such as coloring substances and coloring substances adhering to the surface of the crystal adduct. It is possible to easily obtain a crystal adduct having excellent thermal stability and excellent coloration. Further, bisphenol A obtained by removing phenol from the crystal adduct is also of high quality and excellent in hue and hardly causes coloration.

  Next, the purification process of the mother liquor will be described. Reference numeral 10 denotes a distillation step including a phenol distillation column, 11 denotes a heating / reduced pressure recovery step, 12 denotes a phenol evaporator, and 5 denotes a phenol purification step.

  Of the mother liquor obtained from the first solid-liquid separation step 7A, the liquid introduced into the distillation step 10 through the line 212 includes (i) a liquid containing a relatively large amount of bisphenol A, and (ii) a heavy impurity 1 And (iii) a liquid containing phenol and water that hardly contain any of them. In addition to distillation, the distillation step 10 may have an isomerization step in which part or all of the inflowing liquid is isomerized using a catalyst.

  The liquid (i) is introduced into the phenol evaporator 12 through the line 215, and after the excess phenol is removed, it is introduced into the first crystallization step 6A.

  The liquid (ii) is introduced into the heating / reduced pressure recovery step 11 through the line 216. In the heating / reduced pressure recovery step 11, a distillation operation is usually performed at a temperature of 100 to 200 ° C. and a pressure of 50 torr to normal pressure, and purified phenol is recovered from the top of the column. This purified phenol merges with the purified phenol from other equipment through the line 217, and is further reused in the BPA reaction step 1 and the crystallization step after adding the raw material phenol from the line 101A. The liquid at the bottom of the distillation column constituting the heating / vacuum recovery step 11 contains heavy impurities 1 and also contains BPA. And separated into mother liquor. This crystal adduct is redissolved and then introduced into the phenol evaporator 12 through the line 218, and is introduced into the crystallization step as in the liquid (i). One mother liquor is usually a liquid containing 70 to 80% by weight of phenol, but contains a large amount of heavy impurities 1 and 2 and its total concentration usually reaches 10 to 20% by weight. This mother liquor is introduced into phenol purification step 5 through line 219.

  The liquid (iii) is introduced directly into the first crystallization step 6A through the line 214.

  The purified phenol obtained from the top of the fourth distillation column constituting the phenol purification step 5 has a good hue, and its hue APHA is 10 or less. This purified phenol is combined with other purified phenol through the line 223 and is recycled for use in the BPA reaction step 1 and the like. The bottom liquid withdrawn from the bottom of the fourth distillation column is usually phenol: 0 to 10% by weight, preferably 0 to 6% by weight, and the rest is bisphenol A, 2,4'-bisphenol A, etc. Of polyphenols and other heavy impurities. Since this bottom liquid is a small amount compared to the production amount, it is discharged out of the system as waste oil through the line 302A.

  According to the above embodiment, while preventing accumulation of by-products and impurities in the reaction system and suppressing loss of active ingredients, it is efficiently and economically produced as a crystal adduct having high purity and good hue. be able to. In addition, according to the purification method of the mother liquor separated from the crystallization product, from the mother liquor containing reactive impurities such as high-boiling products such as sulfonated products derived from the catalyst, colored impurities and products that easily cause coloring, those High boilers and reactive impurities can be efficiently and economically removed as waste oil or tar-like substances. The treated purified mother liquor contains phenol and bisphenol A and can be advantageously recycled for use in the reaction step of acetone and phenol and the crystallization step of the crystal adduct. And by recirculating and using such purified mother liquor, accumulation of by-products and impurities in the reaction system can be prevented.

<Incorporation of the decomposition process TD for decomposing waste polycarbonate into the production process of bisphenol A>
Waste polycarbonate used for compact disc (CD), CD-R, DVD (digital video disc) and the like (or may contain some amount of impurities such as other plastics as long as waste polycarbonate is mainly used) is shown in the figure. Thus, it decomposes | disassembles into the decomposition solution containing a phenol by the decomposition | disassembly process 51 which thermally decomposes through the crushing process 50. This decomposition solution is supplied to the concentration step 2 through the line 108 after independently synthesizing the BPA through the BPA synthesis step 52 provided with a strong acid ion exchange resin or the like. In the case where 2 is hardly contained and the coloring property is low, the form may be directly supplied to the BPA reaction step 1 as indicated by a line 108A. You may make it supply a decomposition solution to both the concentration process 2 and the BPA reaction process 1. FIG.

  In the pulverization step 50, waste polycarbonate (waste PC) is received, stored, and pulverized. The degree and shape of pulverization are not particularly limited, but the smaller the smaller, the larger the specific surface area and the faster the decomposition speed. If it is a predetermined shape, the crushing step can be omitted. As a magnitude | size of the resin piece after a grinding | pulverization, 0.5-20 mm is desirable. In addition, the shape of the resin piece may be, for example, a spherical shape, a flake shape, a block shape, a powder shape, a pellet shape, or the like. The crushing method is not particularly limited as long as the molded product is crushed finer than the original size, and a crusher such as a roll that is usually used may be used.

  In the decomposition step 51, the pulverized waste polycarbonate is decomposed and decomposed to isopropenylphenol and the like. Polycarbonate has a specific gravity of 1.2, phenol has a specific gravity of 1.07, and resin pieces are precipitated. Therefore, it is desirable to provide a stirring means in the thermal decomposition tank.

  The decomposition step includes heating with an aromatic monohydroxy compound and decomposing by transesterification (method described in JP-A-6-287295), water-miscible organic solvent (such as methanol) And a contact with an ammoniacal aqueous solution (Japanese Patent Laid-Open No. 10-95741, US Pat. No. 4,885,407), cyclic hydrocarbon and its hydroxy compound (cyclohexanol, etc.), carbonyl compound (cyclohexanone, etc.), unsaturated substance as solvent (Cyclohexene or the like) can be used, for example, a thermal decomposition method. A supercritical medium or a subcritical medium (Japanese Patent Laid-Open No. 2002-155162) may be used as the solvent.

  When employing a pyrolysis step, it can be carried out in the presence of at least one basic catalyst of sodium carbonate and calcium carbonate. The heating temperature is preferably 150 ° C. to 450 ° C., particularly 250 ° C. to 400 ° C. As the solvent, it is desirable to use a cyclic hydrocarbon and a hydroxy compound thereof (such as cyclohexanol), a carbonyl compound (such as cyclohexanone), or an unsaturated substance (such as cyclohexene).

  The input amount of the waste polycarbonate decomposition / resynthesis solution is not limited, but is preferably about 13% by mass or less based on the bisphenol A production amount of the existing bisphenol A production facility.

<Example of azeotropic agent recovery process>
As the azeotropic agent recovery step, it is desirable to use a distillation column. Specifically, as shown in FIG. 2, a first distillation column 41A and a second distillation column 41B are provided, the light impurities 1 are extracted from the top of the first distillation column 41A, and the second distillation column 41B starts from the top. A form is proposed in which light impurities 2 are extracted from the bottom of the azeotropic agent.

  Further, as shown in FIG. 3, a first distillation column 41A and a second distillation column 41B are provided, and light impurities 2 are extracted from the bottom of the first distillation column 41A, and light impurities 1 are extracted from the top of the second distillation column 41B. The azeotropic agent may be withdrawn from the bottom of the column.

  Furthermore, when the amount of the light impurities 2 is small, as shown in FIG. 4, a single distillation column 41A may be provided, the light impurities 1 may be extracted from the column top, and the azeotropic agent may be extracted from the column bottom.

  In these forms, a reflux condenser is provided at the top and bottom of each distillation column.

(Comparative Example 1)
Table 1 shows an operation example when the waste polycarbonate decomposition solution is not added.

Example 1
Table 2 shows an example of operation when waste polycarbonate is charged as shown in FIGS. The numerical value in the uppermost column in each table indicates the same part as the entry in FIG. Moreover, the numerical value in a column shows the weight percentage of each component.

  From these comparisons, it can be seen that even when waste polycarbonate is charged, the purity of bisphenol A obtained is 99.9%, which is the same as that when no waste is charged. Therefore, it can be seen that it is economically meaningful to incorporate a decomposition process for decomposing waste polycarbonate into the production process of bisphenol A.

(Comparative Example 2)
Comparative Example 2 is an example in which the waste polycarbonate decomposition solution is added, but the azeotropic agent is not recovered.
Similar to Example 1, an 8 cubic meter tank is used for the liquid-liquid separation step. In this tank, in order to absorb the fluctuation of the flow rate depending on the liquid level, the capacity difference that is the fluctuation width is about 1.7 cubic meters.
In a liquid-liquid separation process in which cyclohexanone 151 kg / h, cyclohexanol 603 kg / h and cyclohexene 99 kg / h flow into a stream containing ethylbenzene 5144 kg / h and water 2552 kg / h, / H, cyclohexanol 23 kg / h, and cyclohexene 0.4 kg / h.
That is, 97% of cyclohexanone, 96% of cyclohexanol, and almost 100% of cyclohexene are transferred to the ethylbenzene phase in the inflowing solvent.
In Example 1, by installing an azeotropic agent recovery step in the ethylbenzene phase, these impurities are removed and accumulation in the ethylbenzene phase is avoided.
However, in Comparative Example 2, when the waste polycarbonate decomposition solution was charged without using the azeotropic agent recovery step, the tank overflowed in about 2 hours due to accumulation of impurities derived from the solvent, and the operation was impossible. It became. Therefore, it can be seen that the azeotropic agent recovery step is effective when there is an unreacted component recovery step using a distillation column using an azeotropic agent when the waste polycarbonate decomposition solution is added.

It is a flow sheet of the manufacturing process of bisphenol A of the present invention. It is a flow sheet which shows a 1st embodiment of an azeotropic agent recovery process. It is a flow sheet which shows 2nd Embodiment of an azeotropic agent collection | recovery process. It is a flow sheet which shows a 3rd embodiment of an azeotropic agent recovery process.

Explanation of symbols

  DESCRIPTION OF SYMBOLS 1 ... BPA (bisphenol A) reaction process, 2 ... Concentration process, 3 ... Low boiling point recovery process, 4 ... Phenol recovery process, 5 ... Phenol purification process, 6A ... 1st crystallization process, 6B ... 2nd crystallization process 7A ... 1st solid-liquid separation process, 7B ... 2nd solid-liquid separation process, 8 ... Phenol separation process, 9 ... Granulation process, 10 ... Distillation process, 11 ... Heating and decompression recovery process, 12 ... Phenol evaporator, 40 ... Liquid-liquid separation step, 41 ... Azeotropic agent recovery step, 50 ... Waste PC grinding step, 51 ... Decomposition step, 52 ... BPA synthesis step.

Claims (10)

The manufacturing method of bisphenol A characterized by including the process of the following description.
(1) a reaction step of reacting acetone with an excess amount of phenol in the presence of a catalyst to produce bisphenol A;
(2) A concentration step for separating the reaction product from the reaction step into a phenol solution containing bisphenol A and a liquid containing unreacted phenol, unreacted acetone and water,
(3) a crystallization step of precipitating a crystal adduct of bisphenol A and phenol from a phenol solution containing bisphenol A;
(4) A commercialization process for obtaining bisphenol A from the crystallized product in the crystallization process,
(5) a low boiling point component recovery step for separating the liquid containing unreacted phenol, unreacted acetone and water from the concentration step into a liquid containing unreacted acetone and a liquid containing unreacted phenol and water; A phenol recovery step for separating the liquid containing the unreacted phenol and water from the boiling component recovery step into a liquid containing the unreacted phenol and a liquid containing water using an azeotropic agent, A separation step having a liquid-liquid separation step of separating water from a liquid containing water,
(6) Decomposition process for decomposing waste polycarbonate,
(7) Take at least one of the following steps (A) and (B).
(A) A decomposition liquid supply step for supplying the liquid decomposed in the decomposition step to the reaction step.
(B) A decomposition solution supply step for supplying the solution decomposed in the decomposition step to a BPA synthesis step for synthesizing bisphenol A, and a synthetic solution supply for supplying a synthesis solution containing bisphenol A obtained by the BPA synthesis step to the concentration step Process.   The method for producing bisphenol A according to claim 1, further comprising a pulverization step of pulverizing waste polycarbonate prior to the decomposition step, wherein the decomposition step decomposes the pulverized product from the pulverization step.   Recovering at least a part of the liquid containing the azeotropic agent used in the separation step, separating impurities contained in the decomposition liquid or the synthesis liquid from the azeotropic agent, and separating the azeotropic agent, The manufacturing method of the bisphenol A of any one of Claims 1-2 including the azeotropic agent collection | recovery process which aims at reuse in a isolation | separation process.   The azeotropic agent recovery step: recovers at least a part of the liquid containing the azeotropic agent after separating the water from the liquid-liquid separation step, and azeotropes with impurities contained in the decomposition liquid or the synthesis liquid. The method for producing bisphenol A according to claim 3, wherein the azeotropic agent is separated from the agent, and the separated azeotropic agent is returned to the phenol recovery step for reuse.   The method for producing bisphenol A according to any one of claims 3 to 4, wherein the azeotropic agent recovery step separates the azeotropic agent, the light impurities 1, and the light impurities 2.   The production of bisphenol A according to any one of claims 3 to 5, wherein the azeotropic agent is one or more selected from the group consisting of benzene, alkylbenzenes, cyclohexanol, cyclohexanone, cyclohexene, and cyclohexane. Method.   The method for producing bisphenol A according to any one of claims 3 to 6, wherein the decomposition step of decomposing the waste polycarbonate uses at least one of phenol and an azeotropic agent used in the separation step as a solvent.   The method for producing bisphenol A according to claim 7, wherein when the phenol is used as the solvent in the decomposition step, the azeotropic agent is not recovered in the separation step. An apparatus for producing bisphenol A, comprising the following means.
(1) Reaction means for reacting acetone with an excess amount of phenol in the presence of a catalyst to produce bisphenol A,
(2) A concentration means for separating the reaction product from the reaction means into a phenol solution containing bisphenol A and a liquid containing unreacted phenol, unreacted acetone and water,
(3) A crystallization means for precipitating a crystal adduct of bisphenol A and phenol from a phenol solution containing bisphenol A,
(4) Productization means for obtaining bisphenol A from the crystallized product in the crystallization means,
(5) Low boiling point component recovery means for separating the liquid containing unreacted phenol, unreacted acetone and water from the concentration means into a liquid containing unreacted acetone and a liquid containing unreacted phenol and water; Phenol recovery means for separating the liquid containing unreacted phenol and water from the boiling point component recovery means into a liquid containing unreacted phenol and a liquid containing water, and water from the liquid containing the water from the phenol recovery means Separating means having a liquid-liquid separating means for separating,
(6) Decomposing means for decomposing waste polycarbonate,
(7) It has at least one means of the following (A) and (B).
(A) Decomposed liquid supply means for supplying the liquid decomposed by the decomposing means to the reaction step.
(B) A decomposition liquid supply means for supplying the liquid decomposed by the decomposition means to a BPA synthesis process for synthesizing bisphenol A, and a synthetic liquid for supplying a synthesis liquid containing bisphenol A obtained by the BPA synthesis process to the concentration process Supply means.   At least a part of the liquid containing the azeotropic agent used in the separation means is recovered, impurities contained in the decomposition liquid or the synthesis liquid are separated from the azeotropic agent, and the separated azeotropic agent is The apparatus for producing bisphenol A according to claim 9, further comprising an azeotropic agent recovery means for reusing in the separation means.

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