KR100786042B1 - Process for producing bisphenol a - Google Patents

Abstract

Method for preparing bisphenol A comprising the following steps:

(a) reacting a feedstock containing phenol and acetone in the presence of an acid catalyst to obtain a product stream; (b) distilling the product stream to remove acetone and obtain a bottoms stream containing bisphenol A, phenol and acid contaminants; (c) crystallizing the bottom stream to obtain crystals of an adduct of bisphenol A and phenol; (d) removing phenol from the crystals to obtain bisphenol A; (e) recycling a portion of the mother liquor to step (a); (f) treating the remaining portion of the mother liquor to purge the residual tar and recover the purified mother liquor, wherein the amount of the remaining portion is 0.5-5 parts by weight per 100 parts by weight of the mother liquor; (g) recycling the purified liquid to step (a); And (h) treating at least one of (i) at least part of the feedstock, (ii) at least part of the product stream, and (iii) at least one part of the mother liquor to remove acid contaminants contained therein. Maintaining the concentration of acid contaminants in the stream fed to step (c) in the range of 0.001-0.5 meq / L.

Description

The manufacturing method of bisphenol A {PROCESS FOR PRODUCING BISPHENOL A}

The present invention relates to an economical process for the preparation of higher bisphenol A which is excellent in color tone and is thermally stable and does not color at high temperatures.

One of the known processes for the preparation of bisphenol A (hereinafter referred to as BPA) is the introduction of crude BPA containing impurities such as reaction byproducts into the crystallizer to form crystals of the phenol and the mother liquor and the adduct of BPA. It includes. Crystals isolated from the mother liquor are introduced into a dephenolation step to remove phenol and obtain high purity BPA. Most mother liquor is recycled to the reaction zone, while some of it is purged and treated to obtain purified mother liquor and residual tar. The purified mother liquor is recycled to the reaction zone.

Crude BPA also contains acid contaminants, which lead to the production of phenol and isopropenyl phenol and degradation of BPA during distillation, crystallization, and other steps. Thus, it is undesirable to allow acid contaminants to accumulate in the system. In this method, acid contaminants may be released from the system along with the tar. However, in order to maintain the concentration of acid contaminants in the process line, the purge flow rate of the tar purge to extract acid contaminants into the process fluid containing impurities such as phenol, 2,4'-BPA, etc. is increased. It is necessary to let. This operation raises the problem of increasing the BPA production cost.

The present invention has been made in view of the above problems and aims to provide an economical way to reduce raw material phenol consumption without adversely affecting the grade of the product BPA.

According to the present invention there is provided a process for the preparation of bisphenol A comprising the following steps:

(a) reacting a feedstock containing phenol and acetone in the presence of an acid catalyst to obtain a product stream containing bisphenol A, phenol and acid contaminants;

(b) distilling the product stream to remove acetone and obtain a bottoms stream containing bisphenol A, phenol and acid contaminants;

(c) crystallizing the bottom stream to obtain crystals of the mother liquor containing acid contaminants and phenols and the adducts of phenol and bisphenol A;

(d) removing phenol from the crystals to obtain bisphenol A;

(e) recycling the first portion of the mother liquor to step (a) as part of the feedstock;

(f) treating the second portion, which is the remainder of the mother liquor, to purge the residual tar and recover the purified mother liquor, wherein the amount of the second portion is 0.5-5 parts by weight per 100 parts by weight of the mother liquor; step;                 

(g) recycling the purified mother liquor to step (a) as part of the feedstock; And

(h) treating at least a portion of the feedstock, (ii) at least a portion of the product stream, and (iii) at least a portion of the first portion of the mother liquor to remove acid contaminants contained therein. Carrying out the step of maintaining the concentration of acid contaminants in said bottoms stream which is fed to step (c) in the range of 0.001-0.5 meq / L.

The invention will be explained in more detail below with reference to the drawings.

Referring to FIG. 1, denoted by (1) is a reactor through which feedstock containing raw material (mixture of phenol and acetone) from line 11 is fed through lines 13 and 15. In reactor 1, acetone and phenol react in the presence of a strong acid catalyst such as a cation exchange resin of the sulfonic acid type. The reaction is generally carried out at a temperature of 45-95 ° C, preferably 55-85 ° C. The reaction pressure hardly affects the BPA production reaction, and is not particularly limited. When the reactor 1 is a fixed bed system, the reaction pressure is preferably in the range of 0.05-0.5 MPa in view of the mechanical strength or catalyst grinding required for the reactor.

The sulfonic acid type cation exchange resin is preferably in the form of a gel and partly with sulfur-containing compounds, preferably compounds having mercapto groups and tertiary nitrogen-containing groups such as, for example, mercaptoalkylpyridine or mercaptoalkylamine Modified. Examples of sulfur-containing compounds include 2-mercaptoethylamine and 2,2-dimethylthiazolidine. The modification of the cation exchange resin can be carried out by reacting the resin with a sulfur-containing compound in water or in an organic solvent to modify a portion of the sulfonic acid group, usually 3-30%, preferably 5-15%, with the sulfur-containing compound. have.

The catalyst is preferably in the form of particles and packed in a cylindrical reactor. The average particle diameter of the catalyst particles is preferably 0.2-2.0 mm, more preferably 0.4-1.5 mm, wherein the uniformity of the particle diameter distribution is 1.0-1.4, preferably 1.0-1.3. The average particle diameter and uniformity of the particle diameter distribution herein are measured in the state where the catalyst particles are expanded with water. Uniformity Z of the particle diameter distribution is defined by the formula:

Z = A / B

Wherein A and B are the opening sizes of the sieve, where 40 and 90 volume% of the catalyst particles, respectively, remain unpassed.

In reactor 1 the reaction mixture is discharged from here as product flow through line 17. Product streams containing bisphenol A, phenol, unreacted acetone, acid contaminants or free acids derived from acid catalysts, reaction by-products, etc. are fed via line 20 to distillation zones 2 such as distillation towers and / or evaporators Where the distillate containing water, unreacted acetone and some phenol is separated and discharged via line 21. The bottoms stream from the distillation zone (2) containing bisphenol A, phenol and acid contaminants is fed via line (22) to the crystallization zone (3), where the bottoms stream is cooled to produce an adduct of bisphenol A and phenol Generate a crystal. After the crystals are separated from the mother liquor containing acid contaminants and phenols, they are sent via line (23) to the next dephenolation step (8). Preferably, the crystallization is repeated two or more times.

In one preferred embodiment, the crystallization in the crystallization zone (3) is carried out in a series of first and second crystallization steps, wherein the crystals obtained in the first crystallization step are dissolved in phenol and are suitable from the second crystallization step. The mother liquor is separated and the resulting solution is crystallized in a second crystallization step.

The first crystallization step preferably uses two series of first and second crystallizers, in which the bottoms stream from the distillation zone is cooled so that the content of fine crystals having a diameter of 100 μm or less is less than 30% by weight. Is carried out in a manner to form relatively large crystals (pure crystalline species). The crystal species-containing slurry in the first crystallizer is fed to a second crystallizer, cooled to a temperature lower than the temperature of the first crystallizer to grow crystal grains, and the content of fine crystals having a diameter of 100 μm or less is 30 Formation product crystals, which are less than% by weight.

Crystals formed in the second crystallizer are separated from the mother liquor and dissolved again into phenol. The solution is crystallized in the second crystallization step and is preferably carried out using two series which are also the third and fourth crystallizers. Thus, the solution is fed to a third crystallizer and cooled to form relatively large crystals (pure crystal species) of the additive product having a content of fine crystals having a diameter of 100 μm or less, which is less than 30% by weight. The crystal species-containing slurry in the third crystallizer is fed to the fourth crystallizer and cooled to a temperature lower than the temperature of the third crystallizer, so that the crystal grains grow and the content of fine crystals having a diameter of 100 μm or less is 30% by weight. Form crystals less than%. The crystals formed in the fourth crystallizer are separated from the mother liquor and melted by heat, and then sent to the next dephenolation step. The mother liquor obtained in the second crystallization step is preferably used to dissolve the additive product crystals obtained in the first crystallization step.

Melt crystals of the adducts of phenol and bisphenol A obtained in the crystallization zone (3) are sent to the dephenolation step (8), where the phenol is removed from the crystals to give bisphenol A, which is obtained in line (32). Recovered through Dephenolation can be carried out by any suitable known method.

In one preferred embodiment according to the invention, dephenolation is carried out by melting the crystals to form a melt containing bisphenol A and phenol and heating the obtained melt to evaporate the phenol. If desired, evaporation may be followed by stripping, for example steam stripping.

Prior to evaporation, the melt is preferably contacted with a cationic donor solid to neutralize the strong acid contained in the melt with the cationic donor solid. By such treatment with a cationic donor solid, decomposition of bisphenol A can be effectively prevented during heating of the melt and high purity higher bisphenol A can be recovered in high yield. As cationic donor solids, glass fibers can suitably be used.

The mother liquor obtained in the crystallization zone (3) generally contains 8-12% by weight of bisphenol A, 75-90% by weight phenol and 5-15% by weight impurities such as polyphenols and acid contaminants such as trisphenol and coumarone compounds. Include. Most of the mother liquor is recycled via lines 24, 31, 12, 13 and 16 and returned to reactor 1 as part of the feedstock. The remainder of another mother liquor, ie 0.5-5 parts by weight per 100 parts by weight of mother liquor, is fed via line 25 to purge recovery zone 4. In the purge recovery zone 4, the liquid is treated to purge the tarry compound and recover the purified mother liquor. The acid compound is also separated from the mother liquor. When the amount of mother liquor supplied to the purge recovery zone 4 is less than 0.5 parts, impurities such as high boiling point substances and acid contaminants are generated in the system to reduce the grade of BPA. The amount of too much mother liquor fed to the purge recovery zone 4 in excess of 5 parts by weight per 100 parts by weight of the mother liquor is not economically beneficial as it increases the consumption of raw materials and increases phenol losses.

Preferably, the purge recovery zone 4 comprises a phenol distillation column, a reactor equipped with an evaporator operated under vacuum conditions and a strong acid type ion exchange resin-containing tower. In purge recovery zone 4, mother liquor stream 25 is first fed to a distillation column to recover phenol as distillate. The bottom stream, concentrated mother liquor, is introduced into a reactor to which a basic catalyst is added, wherein the bisphenols, trisphenols and other polyphenols contained in the bottom stream are thermally decomposed into isopropenylphenol and phenol by the solvent, while chromans) Impurities such as compounds condense to form high-boiling substances, tars.

The vapor of isopropenyl phenol and phenol recovered from the reactor is introduced into a condenser, where the steam is contacted and condensed with the distillate from the distillation column. The condensed vapor is then fed to a strong acid type ion exchange resin-containing tower so that bisphenol A is formed as a result of the reaction of phenol and isopropenyl phenol. The effluent from the tower represents the purification liquid obtained from the purge recovery zone 4 and is recycled to reactor 1 via lines 27, 12, 13 and 16. The high boiling point material obtained in the reactor is discharged as residual tar via line 26.

If desired, the tar from line 26 can be used as fuel oil by mixing and diluting with ether by-product oil comprising aromatic ethers obtained from the phenol production process. Tar at 180-230 ° C. is fed to the mixing zone and diluent by-product oil comprising aromatic ether is fed for mixing with tar at 60-170 ° C. The mixing ratio of diluent to tar is 0.1: 1 to 2: 1. The mixture released from the mixing zone is cooled and the temperature of the cooled mixture is 80-150 ° C. A portion of the cooled mixture is recycled to the mixing zone along with the remainder recovered as fuel oil.

In the present invention, the concentration of acid contaminants in the stream 22 which is fed to the crystallization zone 3 is in the range of 0.001-0.5 meq / L (milliequivalent / liter) in order to obtain high quality crystals of the adduct in the crystallization zone (3). , Preferably in the range of 0.001-0.10 meq / L. Such higher crystals are substantially free of acid contaminants in terms of acid content in the crystal melt. When the concentration of acid contaminants in the stream 22 fed to the crystallization zone 3 exceeds 0.5 meg / L, some of the acid contaminants are included in the crystals of the additive product obtained in the crystallization zone. As a result, in the subsequent dephenolation step (8), acid contaminants cause degradation of the BPA, increasing the phenol content in the BPA and increasing the coloring and decomposition of the product BPA.

Thus, in the present invention,                 

(i) at least a portion of the feedstock introduced into reactor 1 via lines 13 and 16,

(ii) at least a portion of the product stream fed from reactor 1 to distillation zone 2 via lines 17 and 20, and

(iii) at least a portion of the mother liquor recycled to reactor (1) via lines (24), (31), (12), (13) and (16)

At least one of is subjected to a treatment for removing the acid contaminants contained therein, so that the concentration of the acid contaminants in the stream 22 fed to the crystallization zone 3 is maintained within the range of 0.001-0.5 meq / L. .

The lower concentration limit of acid pollutants is 0.001 meq / L from an economic point of view, since a huge acid removal system is required to reduce the concentration of acid pollutants to extremely low levels in the bottom stream.

Acid contaminants can be removed by contacting the acid contaminant containing fluid with an adsorbent that elutes little impurities. Examples of such adsorbents include activated carbon, alkaline inorganic oxides and anion exchange resins. Anion exchange resins are preferably used. While various anion exchange resins can be suitably used for the purposes of the present invention, the use of anion exchange resins having weak basic anion exchange groups such as primary, secondary, or tertiary amines is preferred. Examples of suitable anion exchange resins include Amberlite (manufactured by Rohm & Haas Company), Dowex (manufactured by Dow Chemical Inc.), and Diaion (manufactured by Mitsubishi Chemical Company).                 

In an exemplary embodiment, (i) some or all of the feedstock in line 13 is introduced into acid treatment zone 5 via line 14 and fed to reactor 1 via line 15, (ii) part or all of the product stream in line 17 is introduced into the acid treatment zone 6 via line 18 and fed to the distillation zone 2 via line 19, and (iii) Some or all of the mother liquor in line 28 is introduced into acid treatment zone 7 via line 29 and fed to reactor 1 via line 31. However, one or two of the treatment zones (5), (6) and (7) can be omitted if desired. Acid contaminants are preferably removed only from the acid treatment zone 7 from an economic point of view. Since the concentration of acid contaminants per volume of flow in line 28 is higher than that in lines 13, 14, 17 and 18, the removal of acid in zone 7 is either zone 5 or More efficient and effective than in (6).

The amount of stream treated in each of the acid removal zones (5)-(7) can be suitably determined according to the concentration of acid pollutants in the stream being treated.

In the present invention, since the acid contaminants in the process stream must be removed in at least one of the acid removal zones (5)-(7), the flow rate of the flow 25 to the purge recovery zone 4 to remove the acid contaminants. It is no longer necessary to increase. The treatment in the purge recovery zone 4 can be performed only for the purpose of reducing impurities other than acid contaminants. Therefore, even when the amount of purge is reduced, the quality of the crystals of the additive product obtained in the crystallization zone 3 is not negatively affected. As a result, the amount of tar released through line 26 can be reduced.

Thus, it is possible to produce higher crystalline additive products of BPA and phenols or free acids free of acid contaminants, thereby producing higher colorant free BPA according to the process of the present invention. Since the amount of purge from the process line is small, the system for processing the purge can be made compressed, where the amount of tar emitted is small. Thus, it is possible to reduce the amount of acetone and phenol supplied as raw material to reduce the production cost of BPA. In addition, the acid treatment in the present invention is carried out to maintain the concentration of acid contaminants in the bottom stream supplied to the crystallization zone in the range of 0.001-0.5 meq / L, so that the working load can be reduced in the acid removal step, The amount of adsorbent may be reduced in acid treatment. Thus, acid can be removed with reduced cost.

The following examples will further illustrate the invention. Percentages are by weight.

1 is a process diagram of a system suitable for carrying out the method for producing BPA according to the present invention.

Example 1

BPA was generated using the apparatus shown in the process diagram of FIG. 1. The acid removal step in (5) and (6) was omitted and the acid treatment was carried out only in step (7). In the crystallization zone (3), the crystals of the adduct were washed with 23.2 kg / h pure phenol. Flow rates, conditions and analytical data are given below.

Reactor 1:

Reaction temperature: 60 ℃

Reaction pressure: 0.3 MPa

Catalyst: Sulfonate type cation exchange resin (manufactured by Rhom &Haas; Amberlite 118-H, average particle diameter: 0.54 mm, uniformity exception particle diameter distribution: 1.46), uniformity of average particle diameter 0.69 mm and particle diameter distribution A filtered product with 1.17 was obtained. The filtered product is treated so that 10% of its sulfonic acid groups are modified with 2-mercaptoamine to obtain a catalyst.

Product flow in line 17 :

Flow rate: 116.7 kg / h

Furtherance

BPA: 18.8%

Phenolic: 73.6%

Water: 1.0%

Acetone: 0.8%

Free acid: 0.086 meq / L

Other Impurities: 5.8%

Distillate in line 21 :

Flow rate: 17.8 kg / h                 

Furtherance

Water: 7%

Acetone: 6%

Phenolic: 86%

Other: 1%

Top bottom flow in line 22 :

Flow rate: 98.9 kg / h

Furtherance

BPA: 22%

Phenolic: 74%

Free acid: 0.101 meq / L

Other Impurities: 4%

Determination of Addition Product in Line 23 :

Flow rate: 22.1 kg / h

Free acid: below the measurement limit

(≤ 0.001 meq / L)

Mother liquor at line 24 :

Flow rate: 100 kg / h

Furtherance:

BPA: 8%                 

Phenolic: 86%

Free acid: 0.1 meq / L

Other Impurities: 6%

Purge in line 25 :

Flow rate: 3 kg / h (3 parts by weight per 100 parts by weight of the mother liquor in line 24)

Purge Recovery Step 4 :

Reactor / vacuum condenser:

Bottom temperature: 250 ℃

Pressure: 0.02 MPa

Strong Acid Ion Exchange Resin Tower

Temperature: 53 ℃

Pressure: 0.1 MPa

Tar in line 26:

Flow rate: 0.2 kg / h

Purification liquid in line 27 :

Flow rate: 2.8 kg / h

Furtherance

BPA: 8%

Phenolic: 89.5%                 

Free acid: below the measurement limit

(≤0.001 meq / L)

Other Impurities: 2.5%

Mother liquor in line 28 :

Flow rate: 97 kg / h

Mother liquor in line 29

Flow rate: 7.0 kg / h

Free acid: 0.1 meq / L

Acid removal step (7) :

Adsorbent: Anion Exchange Resin with Secondary Amine

        (Amberlite manufactured by Rhom & Haas)

Temperature: 50 ℃

Treatment liquid in line 30 :

Free acid: below the measurement limit

(≤0.001 meq / L)

Feedstock in line 16 :

Flow rate: 116.7 Kg / h

Free acid: 0.078 meq / L

BPA from line 32 :

Flow rate: 13.0 kg / h                 

Free acid: below the measurement limit

(≤0.001 meq / L)

Phenolic: Less than 15 ppm by weight

Comparative Example 1

The same procedure as described in Example 1 was repeated except that no acid removal treatment in zone 7 was performed. Thus, the mother liquor in line 28 passed directly through line 31 and was fed to reactor 1. In this case, the concentration of free acid (acid contaminants) in the bottoms stream in line 22 was greater than 0.101 meq / L. In order to maintain the free acid content in line 22 at 0.101 meq / L, it was necessary to increase the amount of mother liquor that was purged through line 25 to 10 kg / h. As a result, the amount of tar released through line 26 increased to 0.7 kg / h. The BPA production cost was therefore higher than in Example 1.

Comparative Example 2

The same manner as described in Example 1 was repeated except that the amount of mother liquor to be purged to line 25 was reduced to 0.5 kg / h without performing the acid removal treatment in zone 7. In this case, the amount of tar released through line 26 was 0.05 kg / h. However, the concentration of free acid in the bottoms stream of line 22 increased above 2.0 meq / L, so that BPA was decomposed in the dephenolation step (8). The BPA product recovered via line 32 had a phenol concentration of 100-1000 ppm by weight.

Claims (7)

Bisphenol A preparation method comprising the following steps: (a) reacting a feedstock containing phenol and acetone in the presence of an acid catalyst to obtain a product stream containing bisphenol A, phenol and acid contaminants; (b) distilling the product stream to remove acetone and obtain a bottoms stream containing bisphenol A, phenol and acid contaminants; (c) crystallizing the bottom stream to obtain crystals of the mother liquor containing acid contaminants and phenols and the adducts of phenol and bisphenol A; (d) removing phenol from the crystals to obtain bisphenol A; (e) recycling the first portion of the mother liquor to step (a) as part of the feedstock; (f) treating the remaining portion of the mother liquor to purge residual tar and recovering the purified liquid, wherein the amount of the second portion is 0.5-5 parts by weight per 100 parts by weight of the mother liquor ; (g) recycling the purified liquor to step (a) as part of the feedstock; And (h) at least one of (i) at least a portion of the feedstock, (ii) at least a portion of the product stream, and (iii) at least one of at least a portion of the first portion of the mother liquor to remove acid contaminants contained therein. Contacting to maintain the concentration of acid contaminants in the stream fed to step (c) in the range of 0.001-0.5 meq / L. delete The method of claim 1 wherein the adsorbent is a basic anion exchange resin. The process of claim 1 wherein step (c) comprises a series of first and second crystallization steps, wherein the crystals obtained in the first crystallization step are dissolved in the mother liquor obtained in the second crystallization step and the solution obtained is And crystallized in a second crystallization step. The method of claim 1, wherein step (d) comprises dissolving the crystals to form a melt containing bisphenol A and phenol, and heating the melt to evaporate the phenol. 6. The method of claim 5, wherein prior to said heating, said melt is contacted with a cationic donor solid to neutralize the strong acid contained in said melt to said solid. 7. The method of claim 6, wherein the cationic donor solid is glass fiber.

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