JP5446067B2 - Method for producing bisphenol A - Google Patents

Description

  The present invention relates to a method for producing bisphenol A. More specifically, the present invention relates to a method for producing bisphenol A comprising a step of treating impurities contained in a part of the mother liquor obtained in the bisphenol A separation step and then re-feeding the reaction system. The present invention relates to a method for producing bisphenol A capable of preventing the deterioration of the activity of the A production catalyst.

  Bisphenol A is usually produced using phenol and acetone as raw materials. As a typical production method, there is a method of reacting the above raw materials in the presence of an acidic catalyst such as a cation exchange resin. The reaction mixture obtained by this method is not limited to bisphenol A which is the target product. Reaction by-products such as unreacted phenol, unreacted acetone, reaction product water and colored substances. As a method for separating these reaction by-products from the reaction mixture, a distillation method is usually employed. In this case, distillation is performed at a temperature lower than the boiling point of phenol in the distillation column, and low-boiling components such as unreacted acetone, reaction product water, and some unreacted phenol are recovered from the top of the column, and bisphenol is recovered from the bottom of the column. A component containing A is obtained. Then, the component containing bisphenol A from the bottom of the tower is separated into a material stream mainly composed of bisphenol A and a mother liquor mainly composed of phenol and reaction impurities.

  Most of the mother liquor is re-supplied to the reaction system, but in order to avoid accumulation of isomers and high-boiling impurities in the reaction system, the mother liquor is usually extracted to remove impurities contained therein. As a method for removing impurities, a method is generally employed in which alkali is added and a heating reaction is performed to decompose bisphenol A and its isomer into phenol and isopropenylphenol. At this time, some of the other impurities become heavy and are removed out of the system as tar. This decomposition reaction is usually carried out by a reactive distillation system, and phenol and isopropenylphenol produced by the decomposition reaction are supplied to a recombination reactor containing an acidic ion exchange resin catalyst to produce bisphenol A ( For example, see Patent Documents 1 to 3). The reaction liquid flowing out from the recombination reactor is re-supplied to the reaction system together with the mother liquid from which impurities have not been removed.

  However, even when a part of the mother liquor is extracted and impurities are removed by alkaline heat treatment, the acidic ion exchange resin catalyst in the reaction process deteriorates, and bisphenol A is produced stably over a long period of time. I couldn't.

  Furthermore, as a result of investigating the activity deterioration of the catalyst by isopropylphenol, it was found that methanol contained in the raw material acetone further promotes the activity deterioration due to isopropylphenol. The raw material acetone contains a trace amount of methanol as an impurity, and it is known that the methanol reduces the catalytic activity of the aminothiol-supported ion exchange resin catalyst (for example, Patent Documents 4 and 5). However, the activity reduction promoting effect with alkylphenols such as isopropylphenol is not known.

Japanese Patent Publication No.49-48319 Japanese Patent Laid-Open No. 1-230538 JP-A-5-331088 JP-A-6-92889 JP-A-6-25047

  The present invention has been made in view of the above circumstances, and its object is to provide a process for producing bisphenol A, which comprises a step of re-supplying the reaction system after impurity treatment of at least a part of the mother liquor obtained in the bisphenol A separation step. Is to provide a method for producing bisphenol A capable of suppressing the deterioration of the activity of the catalyst for producing bisphenol A.

  In order to solve the above-mentioned problems, the present inventors have intensively studied, and as a result, isopropylphenol by-produced when removing impurities by heat treatment in the presence of alkali is an acidic ion exchange resin catalyst in the reaction step. It is a substance that promotes the deterioration of the activity of the catalyst, and it has been found that by controlling the amount of isopropylphenol in the reaction solution in the reaction step within a specific range, the deterioration of the acidic ion exchange resin catalyst in the reaction step can be suppressed, The present invention has been completed.

The gist of the present invention is that a reaction step of reacting raw material components acetone and phenol in the presence of an acidic ion exchange resin catalyst to obtain a reaction mixture containing bisphenol A and phenol, the reaction mixture comprising a component containing bisphenol A and A low-boiling component separation step for separating into a low-boiling component containing unreacted acetone, a bisphenol A separation step for separating a component containing bisphenol A into a substance stream containing bisphenol A as a main component and a mother liquor containing phenol as a main component. , A light component separation step in which at least a part of the separated mother liquor is separated into a light component and a heavy component by heat treatment and distillation in the presence of alkali, and the separated light component is present in the presence of an acidic ion exchange resin catalyst. Recombination reaction process to convert bisphenol A by recombination of phenol and isopropenyl phenol in the light component And a recombination reaction liquid circulation step for circulating the recombination reaction liquid to the reaction step, wherein the content of isopropylphenol in the reaction liquid in the reaction step is 0.3% by weight. Thus, the present invention resides in a method for producing bisphenol A, which is controlled to 2.1% by weight or less .

  According to the production catalyst for bisphenol A of the present invention, the production catalyst for bisphenol A includes the step of supplying at least a part of the mother liquor obtained in the separation step of bisphenol A to the reaction system after treating impurities. It is possible to prevent deterioration of the activity.

  Hereinafter, the present invention will be described in detail. However, the description of the constituent elements described below is a representative example of embodiments of the present invention, and the present invention is not limited to these contents. The method for producing bisphenol A according to the present invention comprises a reaction step of reacting raw material components acetone and phenol in the presence of an acidic ion exchange resin catalyst to obtain a reaction mixture containing bisphenol A and phenol, and the reaction mixture is bisphenol A. A low boiling point component separation step for separating a component containing bisphenol A and a low boiling point component containing unreacted acetone, a substance stream containing bisphenol A as a main component, and a mother liquor mainly containing phenol and reaction byproducts A bisphenol A separation step, a light separation step that separates at least a part of the separated mother liquor into a light component and a heavy component by heat treatment in the presence of alkali and distillation, and a separated light component Treatment in the presence of an acidic ion exchange resin catalyst recombines phenol and isopropenyl phenol in the light component to form vinyl. Encompasses recombination reaction step of converting the phenol A, the recombination reaction between recombination reaction liquid circulating step circulating in the reaction process at least. Furthermore, if necessary, the reaction can be performed without separating and recovering unreacted acetone from the low boiling point component obtained in the low boiling point component separation step and circulating it to the reaction step without treating a part of the separated mother liquor. A mother liquor circulation process that circulates in the process may be included.

  First, in order to facilitate understanding of the present invention, an outline of a method for producing bisphenol A will be described based on the flowchart of FIG. 1, but various embodiments of the production method of the present invention are possible.

  Acetone and phenol as raw materials are supplied to the reactor (2) via the line (1). The reaction mixture from reactor (2) is introduced into distillation column (4) via line (3). Low boiling components including acetone, water, phenol and the like extracted from the top of the distillation column (4) are transferred to the separation system (20) and separated into acetone, water and phenol by distillation or the like. Acetone is transferred to a methanol removal apparatus (1a) as a purifier to be described later via the line (21) and the line (A). Water is discharged out of the system from the separation system (20). Phenol is supplied from the separation system (20) to the purifier (20a) and purified, and then transferred to the phenol storage tank (22).

  The bottom component of the distillation column (4) is transferred to the crystallizer (5) to precipitate a crystal adduct formed by adding bisphenol A and phenol. This crystal adduct is solid-liquid separated by a solid-liquid separator (6), then re-dissolved by a re-dissolver (7), re-crystallized by a re-crystallizer (8), and constituted by a centrifugal separator or the like. Processed in a solid-liquid separation and rinsing system (9). Here, rinsing (cleaning) of the crystal adduct is performed with clean phenol supplied from the tank (22). The rinse waste liquid is transferred to the re-dissolver (7) via the line (10) (or used for rinsing the solid-liquid separator (6) via the line (17)). The rinsed crystal adduct is heated by an adduct decomposition apparatus (11) and decomposed into bisphenol A and phenol, and bisphenol A is processed by a purifier (12) to become product bisphenol A. The phenol separated in the adduct decomposition apparatus (11) and the purifier (12) is transferred to the tank (22).

  At least a part of the separation liquid (mother liquid) separated by the solid-liquid separator (6) is supplied to the impurity removal line (13 ') to be subjected to impurity removal processing. In the impurity removal treatment, at least a part of the mother liquor is concentrated in the mother liquor concentrating tower (13c) and then heat-treated in the presence of alkali in the alkali decomposition tower (13a), and then separated into light and heavy components. The light component is recombined in the recombination reactor (13b) and returned to the line (13) again. A part of the mother liquor may be transferred to the mother liquor tank (14) via the line (13). The mother liquor in the mother liquor tank (14) is transferred to the line (1) via the line (15), mixed with acetone, and supplied to the reactor (2). Furthermore, the mother liquor in the mother liquor tank (14) is also transferred to the line (3) via the line (16).

  The amount of mother liquor supplied from line (15) to line (1) is controlled so that the ratio of acetone to phenol is within a predetermined range in the mixture of acetone and mother liquor supplied to reactor (2). Is done. When the ratio of acetone to phenol is within a predetermined range, the quality and yield of the product bisphenol A are stabilized. The mother liquor tank (14) serves as a buffer tank for leveling fluctuations in the circulation amount from the line (13).

  Next, each step will be described in detail.

<Reaction process>
In the reaction performed in the reactor (2), the raw material phenol and acetone are reacted in a stoichiometric excess of phenol. The molar ratio of phenol to acetone (phenol / acetone) is usually 3 to 30, and preferably 5 to 20. The reaction temperature is usually 50 to 100 ° C., and the reaction pressure is usually atmospheric pressure to 600 kPa (absolute pressure).

  The raw material acetone can be used without particular limitation as long as it is industrially available. For example, it is possible to use purified acetone newly supplied from outside the system, acetone obtained by further treating unreacted acetone separated in the low boiling point component separation step described later in the acetone circulation step, and a mixture thereof. .

  As the catalyst, a strong acid cation exchange resin such as a sulfonic acid type, preferably a resin obtained by partially modifying a strong acid cation exchange resin with a sulfur-containing amine compound is used. In particular, when a resin modified with a sulfur-containing amine compound such as 2-aminoethanethiol or 2- (4-pyridyl) ethanethiol is used, the effect of the present invention becomes remarkable. The degree of modification with the sulfur-containing amine compound is usually 2 to 30 mol%, preferably 5 to 20 mol%, based on the acid group (sulfonic acid group) in the acidic ion exchanger.

  The condensation reaction between phenol and acetone is usually carried out by a fixed bed flow system or a suspension bed batch system. In the case of a fixed bed flow system, the liquid space velocity of the raw material mixture supplied to the reactor is usually 0.2 to 50 / h. In the case of the suspension bed batch method, the amount of the acidic ion exchange resin catalyst used is usually 20 to 100% by weight with respect to the raw material mixture, and the reaction time is usually 0.5 to 5 hours, although it depends on the reaction temperature and reaction pressure. is there.

<Low boiling point component separation step>
The reaction mixture obtained in the reaction step is separated into a component containing bisphenol A and a low-boiling component containing unreacted acetone. As the separation method, as described above based on the flow chart of FIG. 1, the distillation tower (4) is used, the reaction mixture obtained in the reaction step is distilled, and the low-boiling component containing unreacted acetone from the top of the tower. Isolate. The tower bottom liquid is a liquid component containing bisphenol A. A well-known thing can be used as a distillation column. When distillation is carried out at normal pressure, it is carried out below the boiling point of phenol, preferably by distillation under reduced pressure. The vacuum distillation is usually performed at a temperature of 50 to 150 ° C. and a pressure of 50 to 300 mmHg. The unreacted phenol contained in the reaction mixture is preferably distilled under the condition of extracting a predetermined amount from the bottom of the column in order to form adduct adduct with bisphenol A in the subsequent crystallization step. The components separated from the top of the distillation column (4) are unreacted acetone, water, methanol contained as impurities, isopropylphenol, unreacted phenol, and the like. By adjusting the amount of isopropylphenol extracted from the top of the column, the concentration of the substance in the reaction solution can be adjusted. For example, when reducing the amount of isopropylphenol in the reaction solution in the main distillation column (4), an operation such as increasing the amount of phenol recovered to the top of the column or lowering the reflux ratio, or By performing an operation of supplying phenol from the outside to the distillation column (4), the above adjustment can be performed efficiently. By such an operation, the amount of isopropylphenol recovered at the top of the column is usually 0.8% by weight or more, preferably 1.5% by weight or more with respect to the amount of the same substance supplied. Good.

  The concentration of bisphenol A in the bottom liquid after separating the low boiling point component from the top is usually 20 to 50% by weight. When the concentration of bisphenol A is smaller than 20% by weight, the yield of bisphenol A is low, and when it is larger than 50% by weight, the viscosity of the concentrated mixed solution becomes high and transfer becomes difficult. The column bottom liquid is transferred to the bisphenol A separation step, and bisphenol A, which is the target product, is recovered.

  In the case of having the above acetone circulation step, the low boiling point components including unreacted acetone, water, phenol and isopropylphenol separated in the low boiling point component separation step are sent to the acetone circulation step comprising the separation system (20). Acetone is fractionated by distillation or the like. The fractionated acetone is preferably fed back to the methanol removal apparatus (1a) in the previous stage of the reaction step to remove methanol as an impurity before being re-supplied to the reaction system as raw material acetone.

  From the aspect of catalyst activity deterioration, the smaller the amount of methanol, the better. However, in order to remove a trace amount of methanol from the raw material acetone, a huge number of distillation towers having a very large number of stages are installed as necessary. Equipment is required and the financial burden is large and not realistic. Considering these, the amount of methanol in the raw material acetone is usually 10 to 500 ppm by weight, preferably 30 to 500 ppm by weight, more preferably 50 to 300 ppm by weight, and this imposes an excessive burden on the purification of acetone. Without being applied, a practical operation in which a decrease in the activity of the catalyst is suppressed can be performed.

  As the separation system (20), a multistage distillation column is usually used. The separated and recovered phenol is usually rectified together with fresh phenol in a purifier (20a), stored in a storage tank (22) for clean phenol, and used for rinsing a crystal adduct described later. In the purifier (20a), isopropylphenol is purged out of the system by distillation or the like. When purging isopropylphenol out of the system by distillation, for example, the temperature is 150 to 190 ° C., the absolute pressure is 300 to 760 mmHg, and the isopropylphenol contained in the phenol is added together with the heavy material contained in the phenol supplied from the outside. The method of purging more is mentioned.

<Bisphenol A separation step>
In the bisphenol A separation step, a material stream containing bisphenol A as a main component is separated from the component containing bisphenol A obtained in the low boiling point component separation step. The method for separating the material flow is not particularly limited, and a known method can be adopted. Here, the “material flow mainly composed of bisphenol A” refers to a material flow containing 50% by weight or more of bisphenol A. That is, cakes and slurries of bisphenol A and phenol adduct crystals or crystals of bisphenol A alone, solids, liquids, gases, slurries, cake-like substances mainly composed of bisphenol A such as molten bisphenol A and gaseous bisphenol A This means a stream, and these may contain impurities such as phenol and reaction by-products. As a method for separating the material stream, the main component is a material stream composed of a cake of adduct crystals of bisphenol A and phenol by crystallization, and phenol containing reaction by-products such as bisphenol A, 2,4-bisphenol A, and chroman. The method of separating into a so-called “mother liquor” material stream is exemplified. In addition to this method, a third component such as water or acetone is added to a solution containing bisphenol A, bisphenol A crystals are directly crystallized instead of adducts, and solid-liquid separation is performed to separate bisphenol A. Examples thereof include a method of distilling a material stream containing bisphenol A under a high vacuum using a distillation tower and distilling bisphenol A from the top of the tower to separate it. Below, the crystallization process and the recovery process of bisphenol A in the method which isolate | separates into the adduct crystal | crystallization and mother liquid of bisphenol A and phenol by performing solid-liquid separation after crystallization as a typical example are demonstrated.

<Crystal crystallization process>
The tower bottom liquid (liquid component containing bisphenol A) from which the low boiling point component has been separated in the low boiling point component separation step is subsequently subjected to crystallization in the crystallization step. In such a crystallization step, the tower bottom liquid is cooled from 70 to 140 ° C. to 35 to 60 ° C. in the crystallizer (5), and the crystal adduct crystallizes into a slurry. This slurry is a solid-liquid separator ( In 6), solid-liquid separation is performed. As the crystallizer (5), a single crystallizer or a crystallizer having a plurality of external coolers capable of switching operation is usually used. When switching operation with a plurality of external coolers, the crystals attached to the external cooler that is not being used are heated and dissolved, and then switched to use continuously, maintaining high performance. The operation of the crystallization process can be performed. In addition, since the crystallization characteristic in a crystallization tank fluctuates at the time of switching an external cooler, the amount of mother liquor separated by the solid-liquid separator (6) may fluctuate. In order to prevent such a change in the amount of the mother liquor supplied from the line (15) to the line (1), a part of the mother liquor is normally bypassed to the rear side of the reactor (2) via the line (16). . When using the crystallization tank which equipped the jacket type cooler as a crystallizer (5), what was equipped with the scraping apparatus which removes the crystal | crystallization adhering to a heat-transfer surface is preferable.

<Bisphenol A recovery process>
The crystal adduct recovered in the solid-liquid separator (6) is redissolved in phenol in the re-dissolver (7), recrystallized in the re-crystallizer (8) to increase the purity, and then centrifuged. Solid-liquid separation and rinsing system (9) constituted by a machine and the like, and rinsed with clean phenol. It is then transferred to the crystal adduct decomposition system (11).

  Note that most of the liquid separated by the solid-liquid separation and rinsing system (9) and the rinsing waste liquid are supplied to the crystal adduct re-dissolving phenol and the solid-liquid separator (6) in the re-dissolver (7). Can be used as a rinse solution. A part of the liquid separated by the solid-liquid separation and rinsing system (9) is circulated to the tank (14) together with the circulating mother liquor.

  In the crystal adduct decomposition apparatus (11), a method is generally used in which the crystal adduct is heated and melted at 100 to 160 ° C., and most of the phenol is distilled off from the obtained melt. In the purifier (12), a method of purifying bisphenol A by removing residual phenol by steam stripping or the like is usually used. This method is described, for example, in JP-A-2-28126 and JP-A-63-132850.

<Mother liquor circulation process>
In the bisphenol A separation step, the mother liquor in the present invention is obtained by removing a material flow mainly composed of bisphenol A from a component containing bisphenol A. For example, after adduct crystallization, bisphenol A is separated by a solid-liquid separator. / The liquid which isolate | separated the phenol adduct body is shown. A part (for example, 85 to 96%) of the liquid (mother liquor) separated by solid-liquid separation in the solid-liquid separator (6) passes through the line (13) and through the line (15) and / or before the reaction step. It is circulated through the line (16) to the rear side of the reaction process. In the present invention, this step is not essential, but by using it together with the light component separation step described later, it is possible to efficiently remove heavy substances and continue stable operation.

  That is, the composition of the mother liquor obtained from the solid-liquid separator (6) is usually 65 to 85% by weight of phenol, 10 to 20% by weight of bisphenol A, and 5 to 15% by weight of by-products such as 2,4′-isomer. Yes, it contains many impurities such as 2,4'-isomer. In order to prevent accumulation of these impurities in the process, a part of the mother liquor obtained from the solid-liquid separator (6) is subjected to a light fraction separation step described later. In this case, the molar ratio (phenol / acetone) of phenol to the total amount (a + b) of the amount of fresh acetone (a) to line (1) and the amount of recovered acetone (b) supplied via line (21) is The mother liquid delivery pump (not shown) from the tank (14) to the line (15) is controlled so that the constant mixing ratio shown above is obtained.

<Light fraction separation process>
In this step, at least a part of the mother liquor separated in the above step is separated into light and heavy components by heat treatment and distillation in the presence of alkali. Specifically, at least a part of the mother liquor is separated from the line (13) to the impurity removal line (13 ′), and the light and heavy components are separated from the light by heavy heat treatment and distillation in the alkali decomposition tower (13a) in the presence of alkali. Separated into masses. Preferably, at least a part of the separated mother liquor is distilled in a mother liquor concentrating column (13c) by distilling most of the isopropyl phenol together with a part of phenol as a light distillate from the top and / or side, and then alkaline. Heating in the presence of the substance decomposes bisphenol A and isomers into phenol and isopropenylphenol. Hereinafter, the case where a light distillate is obtained from the top of the column will be described as an example.

  Since the phenol recovered from the top of the mother liquor concentration tower (13c) contains a large amount of isopropylphenol, at least a part of this liquid is branched and purged outside the system via the line (13d), or At least a portion is branched and supplied to the purifier (20a) to purify and remove isopropylphenol, whereby the isopropylphenol concentration in the reaction solution can be adjusted. By performing it together with the separation operation of isopropylphenol in the distillation column (4), the isopropylphenol concentration can be controlled more efficiently.

  Of the phenol recovered from the top of the mother liquor concentration tower (13c), the phenol not purged out of the system via the line (13d) is used for cooling (quenching) the top of the alkali decomposition tower (13a). The The amount of isopropylphenol purged out of the system via the line (13d) and contained in the phenol is preferably 5% by weight or more of the amount of isopropylphenol supplied to the mother liquor concentration tower (13c). It is more preferable that it is weight%, and it is especially preferable that it is 7 to 15 weight% or more. When the extraction amount of isopropylphenol is less than the above range, it may be difficult to keep the content of isopropylphenol in the reaction solution in the reaction step within a predetermined range. Further, in order to increase the amount of isopropylphenol purged out of the system via the line (13d), it is necessary to increase the amount of phenol purged, which may cause phenol loss. In particular, when phenol that has not been purged out of the system is used for cooling (quenching) the top of the alkali decomposition tower (13a), the amount of phenol used for cooling (quenching) decreases, so cooling (quenching) May be insufficient. Moreover, when there is too little quantity of the phenol used for cooling (quenching), the density | concentration of the isopropenyl phenol in the light part obtained from an alkali decomposition tower (13a) becomes high. When the concentration of isopropenylphenol is high, dimerization of isopropenylphenol occurs or the selectivity in the recombination reaction step described later tends to deteriorate.

  In the mother liquor concentration column (13c), the amount of isopropylphenol recovered at the top of the distilling column was supplied by performing operations such as increasing the amount of phenol recovered at the column top and decreasing the reflux ratio. The amount of the same substance is usually 0.6 or more, preferably 0.8 or more. Further, the ratio of branching out of the distillate is preferably 0.1 or more. At this time, if it is necessary to control the ratio of phenol and isopropenylphenol by reducing the amount of phenol supplied to the recombination reactor (13b) in the subsequent step, the operation of supplying phenol from the outside is also combined. It can also be done.

  The above decomposition reaction is preferably carried out by a reactive distillation method in which a mother liquor and an alkaline substance are supplied to the alkali decomposition tower (13a) and heated to 200 to 300 ° C. for decomposition. As the alkaline substance, known alkaline substances such as hydroxides of alkali metals such as sodium and potassium, carbonates, phenol salts, hydroxides of alkaline earth metals such as magnesium and calcium, and phenol salts can be used. The alkaline substance is preferably supplied in the form of an aqueous solution. The decomposition rate of bisphenol A and isomers in the alkali decomposition step is usually 30% or more, preferably 50% or more, more preferably 60% or more.

  As disclosed in JP-A-10-218814, the above mother liquor may be concentrated in advance and subjected to a decomposition reaction, or may not be concentrated and may be subjected to a decomposition reaction. This is because even if the mother liquor is subjected to the decomposition reaction as it is, the phenol in the mother liquor is immediately evaporated and concentrated. The mother liquor to be treated with impurities is alkali-decomposed in the alkali decomposition tower (13a) and separated into a light component containing phenol and isopropenylphenol and a heavy component such as tar. Heavy components are released out of the system.

<Recombination reaction step>
The above light components are subjected to a recombination reaction treatment in a recombination reactor (13b). That is, the above-mentioned isopropenylphenol is a polymerizable substance and easily forms a polymer. Therefore, if the light component containing isopropenylphenol is returned to the mother liquor circulation line (13) as it is, a problem arises that the product bisphenol is colored by this polymer. Therefore, the light components (phenol and isopropenylphenol) distilled from the top of the alkali decomposition tower (13a) are immediately condensed and supplied to the recombination reactor (13b), and re-reacted in the presence of the acidic ion exchange resin. By performing the binding reaction, the formation of a polymer as a coloring component is suppressed.

  The recombination reaction is usually performed at a temperature of 50 to 85 ° C. As the strong acid cation exchange resin used for the recombination reaction, a strong acid cation exchange resin such as a sulfonic acid type is usually used. In addition, you may use the same thing as the sulfonic acid type strong acidic cation exchange resin partially neutralized with the sulfur-containing amine compound used at a reaction process.

  In the recombination reaction, a side reaction in which isopropenylphenol is dimerized may occur. By setting the molar ratio of phenol to isopropenylphenol supplied to the recombination reactor (13b) to be 40 or more, this side reaction occurs. It is preferable because the reaction can be remarkably suppressed. When the molar ratio of phenol to isopropenylphenol is 40 or more, it is preferable to additionally supply external phenol (such as phenol used for washing crystals in the crystallization step).

<Recombination reaction liquid circulation process>
The recombination reaction liquid (bisphenol A production liquid) obtained in the above step is returned to the mother liquor circulation line (13).

  In the method for producing bisphenol A of the present invention, the content of isopropylphenol in the reaction solution in the reaction step is 4% by weight or less, preferably 2% by weight or less, more preferably 1% by weight or less, particularly preferably 0.5% by weight. % Or less. The present inventors have promoted the deterioration of the activity of the acidic ion exchange resin catalyst in the reaction step by isopropylphenol (including o-, m-, p-isomers and a mixture thereof) contained as an impurity in the reaction solution in the reaction step. It was found that it is a substance to be made. Furthermore, it has also been found that this isopropylphenol is by-produced by heat treatment in the presence of alkali in the impurity treatment step. Therefore, in the method for producing bisphenol A having the above-described impurity treatment step, mixing of isopropylphenol is unavoidable, and as the impurity treatment is performed, isopropylphenol accumulates in the system. Therefore, in the present invention, the content of isopropylphenol in the reaction solution in the reaction step is controlled to 4% by weight or less. Thereby, deterioration of the acidic ion exchange resin catalyst in the reaction step can be suppressed. The concentration of isopropylphenol in the reaction solution in the reaction step may be based on any of the reactor inlet, the reactor interior, and the reactor outlet. To prevent deterioration of the ion exchange resin, the reactor inlet is It is preferable to adjust as a reference.

  As a method for controlling the content of isopropylphenol in the reaction solution in the reaction step to 4% by weight or less, 5 to 20% by weight, preferably 5 to 15% by weight of the mother liquor supplied to the light fraction separation step. Is preferably separated as a heavy component. This is based on the fact that the present inventors have found that there is a correlation between the amount of alkylphenol produced in the system and the amount of heavy component (tar component) discharged from the alkali decomposition tower (13a). . The requirements for adjusting the discharge amount of the heavy component are the residence time of the mother liquor in the alkali decomposition tower (13a), the alkali concentration, the decomposition temperature, the degree of reduced pressure, and the like. The discharge amount can be adjusted to the above range.

  Specifically, the residence time of the mother liquor in the alkali decomposition tower (13a) is usually 1 to 20 hours, preferably 2 to 10 hours, and the alkali concentration (heavy fraction removed from the system in the light fraction separation step). The alkali concentration in metal (in terms of metallic sodium) is usually 100 to 4000 ppm by weight, preferably 200 to 2000 ppm by weight, and the decomposition temperature is usually 170 to 300 ° C, preferably 200 to 250 ° C. Is usually 10 to 100 Torr, preferably 20 to 50 Torr, before adjusting the fraction of the mother liquor fractionated from the line (13) to the impurity removal line (13 ′) or adding an alkali, When the phenol was distilled in the mother liquor concentration tower (13c), isopropylphenol was extracted together with the phenol, so the distillation rate was changed. Alternatively, the content of isopropylphenol in the reaction solution in the reaction step can be adjusted by adjusting the amount extracted from the line (13d) to the purifier (20a). The method of adjusting the amount extracted to 20a) is preferable because isopropylphenol can be extracted efficiently, and the amount supplied to the line (13) from the recombination reactor (13b) is adjusted, The content of isopropylphenol in the reaction solution in the reaction step can also be adjusted by adjusting the amount of fresh phenol, and the isopropylphenol is distilled from the light fraction obtained from the alkali decomposition tower (13a). The operating conditions of the alkali decomposition tower (13a) can be removed. How to more controlled is preferably simple.

  In addition, in the production method of the present invention, in addition to the above-described operation, for the hydrated phenol generated by the dehydration operation at the start of use of the reaction catalyst, during operation, the hydrated phenol is supplied little by little to the distillation column in the process, It is preferable to reuse phenol by dehydration because the phenol used as a raw material can be reused.

  As described above, as a preferred embodiment of the present invention, a condensation reaction proceeds by adding acetone and a large excess of phenol to a reactor filled with a sulfonic acid type ion exchange resin modified with an aminothiol compound. A is generated. In this case, the sulfonic acid-type ion exchange resin catalyst used as the catalyst has a bisphenol A production reaction for a long period of time, so that the aminothiol compound acting as a co-catalyst is denatured and its effect is lost. A heavy product such as tar, which is a by-product, adheres to the surface, and the catalyst surface may be covered, resulting in a decrease in catalyst activity. Therefore, it is necessary to periodically remove these catalysts from the reactor and replace them.

  The catalyst newly added by exchange may be a newly produced catalyst, or surface tar or modified by treating the used catalyst extracted from the reactor with reduced activity with an acid or the like. After removing the cocatalyst, a sulfonic acid type ion exchange resin catalyst modified again by impregnation with a solution containing an aminothiol compound may be used.

  The filling of the ion exchange resin catalyst into the reactor is usually performed in a state where the ion exchange resin catalyst is swollen with water. Therefore, it is preferable that the charged ion exchange resin catalyst is dehydrated before the production reaction of bisphenol A. The dehydration operation of the ion exchange resin is usually performed by removing coarse water and then bringing it into contact with phenol. Since the volume of the water-swollen ion exchange resin is rapidly reduced by dehydration, the ion exchange resin itself may be damaged by the dehydration operation. Therefore, the first dehydration operation is preferably performed using a mixed solution of about phenol / water = 9/1. Since this operation can suppress a rapid volume change, the ion exchange resin can be prevented from being damaged.

  About the contact method of the phenol in dehydration operation, you may impregnate by batch operation and you may distribute | circulate phenol continuously. The phenol to be used may be purified pure phenol, or may be a filtrate (mother liquor) generated in a solid-liquid separation step that is recycled in the bisphenol A process.

  Phenol used in the dehydration operation contains water and acidic components desorbed from the sulfonic acid type ion exchange resin, and therefore, it is preferable to purify and reuse. The method for purifying the phenol used in the dehydration operation is not particularly limited. A method for purifying by storing it in a tank or the like and returning it to the process little by little when the operation is restarted, a method for purifying using a dedicated distillation column, etc. Etc. In addition, when two or more reactors are installed and operated in parallel, dehydration treatment of one or more other stopped reactors is performed simultaneously while operating one or more reactors. The unpurified phenol generated in the process may be returned to the process.

  When returning to the process, it may be supplied to the distillation column of the low boiling point component separation step for removing unreacted acetone, water, etc. downstream of the reactor, or supplied before the impurity removal treatment to purify phenol. May be performed. Moreover, you may carry out combining these. In general, since there is a possibility that an acidic component contained in the unpurified phenol is contained in the product bisphenol A, it is preferable to supply it before the impurity removal treatment, but the impurity removal treatment occurs at the beginning of the dehydration operation. If phenol with a high water content is supplied, water is mixed into the alkaline decomposition tower for impurity removal treatment, and alkaline decomposition is performed under conditions of high temperature (over 200 ° C) and high pressure reduction (under 80mmHg). Operation of the process may be difficult because high vapor pressure may not be maintained due to the vapor pressure of the mixed water. For this reason, it is preferable to treat the phenol having a high water content at the beginning of the dehydration operation in the low boiling point component separation step, and switch to the supply before the impurity removal treatment when the water content in the phenol decreases.

  The purified phenol is used as a phenol for washing adduct crystals in a solid-liquid separation process.

  EXAMPLES Hereinafter, although an Example demonstrates this invention still in detail, this invention is not limited to a following example, unless the summary is exceeded.

(1) Analysis method of acetone:
The measurement was performed with a gas chromatograph apparatus (GC-14B manufactured by Shimadzu Corporation) equipped with a fused silica capillary column and a TCD detector.

(2) Isopropylphenol analysis method:
A gas chromatograph apparatus (GC-14B manufactured by Shimadzu Corporation) equipped with a fused silica capillary column and an FID detector was used.

(3) Acetone conversion:
It calculated | required with the following formula | equation.

Example 1:
Bisphenol A was continuously produced by a pilot experimental facility having the flow shown in FIG. The diameter of the reactor (2) installed in the reaction process is 660 mm, and sulfonic acid type cation exchange resin (“Diaion SK-104H” manufactured by Mitsubishi Chemical Corporation) is used as a catalyst in this reactor. -Pyridyl) Ion exchange resin 340L modified with 20 mol% of sulfonic acid group with ethanethiol was filled. The reactor (2) filled with the catalyst was mixed with a mother liquor and acetone (82% by weight phenol, 4% by weight acetone, 8% by weight bisphenol A and 6% by weight of other components) fed from the line (15). The methanol concentration contained in acetone is 100 ppm by weight) at a flow rate of 400 kg / h, and the reaction was carried out at 65 ° C. The liquid from the line (3) was supplied to a distillation column (4) equipped with a packing so that the number of theoretical plates was 7, and 62 kg / h was withdrawn from the top of the column. At this time, the amount of isopropylphenol extracted from the top of the distillation column (4) was 1.6% by weight of the supplied amount. The bottom liquid of the distillation tower (4) was supplied to the crystallization tower (5) to crystallize bisphenol A and phenol adduct crystals. The obtained adduct crystal was separated into a solid (78 kg / h) and a mother liquor (385 kg / h) by a solid-liquid separator (6) including the purified phenol (120 kg / h) used for rinsing. The liquid from the line (13 ′) was supplied to the mother liquor concentrating tower (13c) equipped with packing so that the number of theoretical plates was 3, and 29 kg / h was withdrawn from the top of the tower. The isopropylphenol was removed by branching 11% of this liquid and discharging it out of the system from the line (13d). At this time, the amount of isopropylphenol discharged out of the system was 10% by weight of the amount supplied to the mother liquor concentration tower (13c).

  Of the mother liquor, 347 kg / h (90% by weight of the total amount of the mother liquor) was directly re-supplied to the reaction step via the line (13), but the remaining 38 kg / h (10% by weight of the total amount of the mother liquor) After the treatment in the mother liquor concentration tower (13c), the tower top liquid and tower bottom liquid that were not discharged out of the system were supplied to the alkali decomposition tower (13a) to remove impurities. In the alkali decomposition tower (13a), 0.22 kg / h of 25 wt% sodium hydroxide aqueous solution was added, and then an alkali decomposition reaction and distillation were performed under the conditions of a temperature of 210 ° C., a pressure of 40 Torr, and a residence time of 4 hours. A mass of 3.8 kg / h (heavy content purge rate of 10% by weight) was separated. The light component from which the heavy component (tar component) has been removed is filled with a sulfonic acid type cation exchange resin ("Diaion SK-104H" manufactured by Mitsubishi Chemical Corporation) that is not modified with a sulfur-containing amine compound maintained at 65 ° C. Then, it was supplied to the recombination reactor (13b) to react bisphenol A with isopropenylphenol produced by the alkali decomposition reaction to form bisphenol A, and then was supplied again to the reaction system via the line (13).

  The continuous operation was performed for 4000 hours by the above operation. The amount of impurities in the system stabilized after 250 hours from the start of operation, and the amount of impurities did not change until 4000 hours thereafter. In this case, the concentration of p-isopropylphenol in the raw material supplied to the reactor (2) is 0.3% by weight, and the isopropylphenol extracted from the top of the distillation column (4) is supplied isopropylphenol. The isopropylphenol discharged out of the system from the line (13d) was 10% by weight of the isopropylphenol supplied to the mother liquor concentration tower (13c). The acetone conversion was 98.5% 1 hour after the start of acetone feed, and then 93.1% after 4000 hours of operation.

Example 2:
The same operation as in Example 1 was performed except that a part of the distillate from the mother liquor concentrating tower (13c) was discharged from the system from the line (13d), and supplied to the reactor (2). The concentration of isopropylphenol in the starting material was stable at 0.8% by weight. The acetone conversion was 98.5% 1 hour after the start of acetone feed, and then 91.8% after 4000 hours of operation.

Example 3:
Except that the discharge of isopropylphenol from the distillate of the distillation column (4) was stopped, the same operation as in Example 1 was performed. As a result, isopropylphenol in the raw material supplied to the reactor (2) was obtained. The concentration of was stable at 1.2% by weight. The acetone conversion was 98.5% 1 hour after the start of acetone feed, and then 90.4% after 4000 hours of operation.

Example 4:
The same operation as in Example 1 was performed except that acetone containing 650 ppm by weight of methanol was used as a reaction raw material. The concentration of isopropylphenol in the raw material supplied to the reactor (2) was 0.4% by weight. And stable. The acetone conversion was 98.0% 1 hour after the start of the acetone supply, and then 88.6% after 4000 hours of operation.

Example 5:
In the light fraction separation step, the temperature of the alkali decomposition tower (13a) is 250 ° C., the heavy fraction to be separated is 0.9 kg / h (heavy fraction purge rate 2.3% by weight), and the mother liquor concentration tower (13c). The amount of isopropylphenol purged from the top of the column via the line (13d) is 20% by weight of the amount supplied to the mother liquor concentration column (13c), and the amount of isopropylphenol extracted from the top of the distillation column (4) Except that the amount was 2.5% by weight of the amount supplied to the distillation column (4), the same operation as in Example 1 was performed. As a result, the concentration of isopropylphenol in the raw material supplied to the reactor (2) Was stable at 2.1% by weight. The acetone conversion was 98.5% 1 hour after the start of acetone supply, and then 88.3% after 4000 hours of operation.

Comparative Example 1:
In Example 1, the operation was performed under the same conditions as in Example 1 except that the reaction distillation conditions by alkali decomposition were changed and the reaction / distillation was performed at 250 ° C. Since the alkali decomposition temperature was higher than that in Example 1, the alkali decomposition proceeded more than in Example 1, and the amount of heavy component removed from the bottom of the column was 0.8 kg / h (heavy component purge rate 2 .3% by weight). The amount of impurities in the system stabilized after 250 hours from the start of operation, and did not change until 4000 hours thereafter. The concentration of isopropylphenol in the raw material supplied to the reactor (2) at that time was 6.3% by weight. Acetone conversion was 98.5% 1 hour after the start of acetone feed, then 80.9% after operation for 4000 hours, and the acetone addition rate was greatly reduced, and the deterioration of the sulfonic acid type cation exchange resin catalyst was remarkable. Recognized by

Comparative Example 2:
The same operation as in Comparative Example 1 was performed except that acetone containing 650 ppm by weight of methanol was used as a reaction raw material. As a result, the concentration of isopropylphenol in the raw material supplied to the reactor (2) was 6.3% by weight. And stable. The acetone conversion was 97.5% 1 hour after the start of acetone supply, and then 71.1% after 4000 hours of operation.

  Although the present invention has been described with reference to the most practical and preferred embodiments at the present time, the invention is not limited to the embodiments disclosed herein. It should be understood that the present invention can be modified as appropriate without departing from the spirit or concept of the invention as read from the claims and the entire specification, and that such changes are also within the technical scope of the present invention. .

It is a flowchart which shows the manufacturing method of the bisphenol A of this invention. It is a flowchart which shows the pilot used in Example 1. FIG.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1a: Methanol removal apparatus 2: Reactor 4: Distillation column 5: Crystallizer 6: Solid-liquid separator 7: Re-dissolver 8: Re-crystallizer 9: Solid-liquid separation and rinse system 11: Crystal adduct decomposition apparatus 12 : Purifier 13a: Alkaline decomposition tower 13b: Recombination reactor 13c: Mother liquor concentration tower 14: Tank 20: Separation system 20a: Purifier 22: Phenol storage tank

Claims (6)

  A reaction step of reacting raw material components acetone and phenol in the presence of an acidic ion exchange resin catalyst to obtain a reaction mixture containing bisphenol A and phenol, the reaction mixture comprising a component containing bisphenol A and low unreacted acetone Low-boiling component separation step for separating into boiling components, bisphenol A separation step for separating components containing bisphenol A into a substance stream containing bisphenol A as a main component and mother liquor containing phenol and reaction by-products as a main component, separation Light separation process in which at least a portion of the mother liquor is separated into light and heavy components by heat treatment and distillation in the presence of alkali, and the separated light components are treated in the presence of an acidic ion exchange resin catalyst. The recombination reaction step of recombining phenol and isopropenylphenol in the light component into bisphenol A And a recombination reaction liquid circulation step for circulating the recombination reaction liquid to the reaction step, wherein the content of isopropylphenol in the reaction liquid in the reaction step is 0.3% by weight or more. 2.1% by weight or less, The manufacturing method of bisphenol A characterized by the above-mentioned.   The method for producing bisphenol A according to claim 1, wherein the acidic ion exchange resin catalyst in the reaction step is a modified acidic ion exchange resin catalyst modified with alkylaminothiol.   The method for producing bisphenol A according to claim 2, wherein the alkylaminothiol is 2-aminoethanethiol and / or 2- (4-pyridyl) ethanethiol. The light fraction separation step has a mother liquor concentration tower prior to the heat treatment, and when at least part of the light distillate obtained from the mother liquor concentration tower is withdrawn from the light separation step as a purge, the mother liquor concentration is performed. The method for producing bisphenol A according to any one of claims 1 to 3 , wherein 5% by weight or more of isopropylphenol supplied to the tower is extracted. The manufacturing method of the bisphenol A as described in any one of Claims 1-4 which isolate | separates 0.8 weight% or more of the supplied isopropyl phenol with a low boiling-point component in a low boiling-point component isolation | separation process. The method for producing bisphenol A according to any one of claims 1 to 5 , wherein the amount of methanol contained in the raw material component acetone supplied to the reaction step is 10 to 500 ppm by weight.

Images