RU2799337C2 - Method of obtaining bisphenol-a - Google Patents

Abstract

FIELD: water purification.

SUBSTANCE: method of producing bisphenol-A that includes the reaction of acetone and phenol in the presence of a catalytic system containing an acidic heterogeneous catalyst and a catalyst promoter, in which at least one organic sulfur-containing compound is present, to obtain an effluent from the reactor containing bisphenol-A, water, unreacted acetone, unreacted phenol, and at least a portion of a catalyst promoter is proposed. At least a portion of the reactor effluent is distilled to remove water, catalyst promoter, and unreacted acetone, and a bottom stream containing bisphenol A is obtained. At least a portion of the remaining flow is then introduced to contact with the main anion exchange resin to obtain purified flow from which bisphenol-A is extracted.

EFFECT: proposed method improves the removal of polysulfonic acids washed out from the heterogeneous acid catalyst from the obtained bisphenol-A.

11 cl, 4 dwg, 6 ex

Description

TECHNICAL FIELD OF THE INVENTION

[0001] The present invention relates to a method for producing bisphenol-A.

State of the art of the present invention

[0002] Bisphenol-A (BPA), also known as 2,2-bis(4-hydroxyphenyl)propane or para,p-diphenylolpropane (p,p-BPA), is an important industrial compound used to make polycarbonates. , as well as other technological thermoplastic and epoxy resins. Bisphenol-A is produced commercially by the condensation of acetone and phenol, and, in fact, BPA production is the largest consumer of phenol. This reaction can take place in the presence of a strong homogeneous acid such as hydrochloric acid, sulfuric acid or toluenesulfonic acid, or in the presence of a heterogeneous acid catalyst such as a sulphonated ion exchange resin. In recent years, acidic ion exchange resins have gained overwhelming advantage as the catalysts of choice for the condensation reaction in the production of bisphenol, and strongly acidic sulfonated polystyrene ion exchange resins are proving to be particularly suitable for use in this regard.

[0003] In industrial practice, two different technologies for the production of bisphenols using heterogeneous acid catalysts predominate. According to one technology, the auxiliary promoter of the catalyst circulates freely in the reactor with the initial reactants. This technology is used to increase the selectivity and/or activity of the reaction. This technology typically uses an alkanethiol, such as methyl mercaptan or ethyl mercaptan, or a mercaptocarboxylic acid, such as 3-mercaptopropionic acid, as a freely circulating co-catalyst promoter. The acid sites of the resin remain accessible because they are generally not associated with a promoter. This provides the flexibility to adjust the optimal promoter concentration for the particular conditions of the reaction in question.

[0004] According to the second technology, in order to use heterogeneous acid catalysts in the production of bisphenols, the catalyst is modified by introducing catalytic auxiliary agents such as thiazolidines and aminothiols into some of the acid active sites of the catalyst. For example, the promoter mercapto groups can bind to the backbone sulfonate ions of the cation exchange resin via covalent or ionic bonds involving nitrogen atoms. For immobile promoter technology, the need for direct handling and processing of promoters is less than for freely circulating promoter technology, but the opportunity for process improvement through differential processing of resin and promoter is greatly reduced.

[0005] Among the requirements for BPA, especially in the case of its use in the production of polycarbonates, include thermal stability and high purity due to stringent conditions of optical transparency and color for the final application. Thus, as is known, for example, from US Pat. No. 5,124,490, contacting the BPA process streams with the main anion exchange bed improves the color and thermal stability of the BPA product by removing trace amounts of acid released from the strongly acidic sulfonated ion exchange resin used as a catalyst. in the condensation reaction of acetone and phenol.

[0006] Although treatment with a basic anion exchange resin is effective in purifying BPA process streams, if the process streams also contain a residual mercaptan promoter such as methyl mercaptan or ethyl mercaptan, it has been found that contact with a basic anion exchange resin can convert the mercaptan to dimethyl sulfide, dimethyl disulfide, diethyl disulfide, hydrogen sulfide or other sulfur compounds. This results in an uneconomical loss of the mercaptan promoter and also requires additional processing steps to remove unwanted sulfur compounds.

[0007] Thus, there is a need for an improved method for purifying BPA process streams produced using heterogeneous acid catalysts promoted with organic sulfur compounds.

Brief summary of the present invention

[0008] According to the present invention, it has been found that in order to realize the quality advantages resulting from contact with the anion exchange bed without losing the mercaptan promoter, the BPA effluent from the reactor should first be distilled to remove the mercaptan promoter and unreacted acetone before contacting the anion exchange bed. In addition, to maximize trace acid trapping, contact with the anion exchange bed should preferably occur before the distillate stream is crystallized or otherwise processed to recover BPA.

[0009] Thus, according to one aspect, the present invention is a method for producing bisphenol-A, and this method includes:

(a) reacting acetone and phenol in the presence of a catalyst system containing an acidic heterogeneous catalyst and a catalyst promoter in which at least one organic sulfur compound is present to produce a reactor effluent containing bisphenol-A, water, unreacted acetone, unreacted phenol and at least a portion of a catalyst promoter;

(b) distilling at least a portion of the effluent from the reactor to remove water, catalyst promoter and unreacted acetone and obtain a residual stream containing bisphenol A;

(c) contacting at least a portion of the residual stream with a base anion exchange resin to obtain a purified stream; And

(d) recovering bisphenol-A from the purified stream.

Brief description of the figures

[0010] FIG. 1 is a simplified flow diagram of a process for producing bisphenol-A according to one embodiment of the present invention.

[0011] In FIG. 2 is a graph illustrating the variation with run time in the concentration of diethyl disulphide (DEDS) in the product obtained in Example 1 using 10 g (on a dry matter basis) of Lewatit® MP 62 WS anion exchange resin at a temperature of 90° C., 110 °С and 120°С.

[0012] FIG. 3 is a graph illustrating the change with run time in the concentration of diethyl disulphide (DEDS) in the product obtained in Example 1 using various amounts of Lewatit® MP 62 WS anion exchange resin at 90°C.

[0013] FIG. 4 is a graph illustrating the variation with run time in the concentration of diethyl disulphide (DEDS) in the product prepared in Example 1 using 10 g (dry basis) of Lewatit® MP 62 WS anion exchange resin and 10 g (dry basis ) Amberlyst™ A26 anion exchange resin, both at 90°C.

Detailed Disclosure of Embodiments of the Present Invention

[0014] The present invention relates to the production of bisphenol-A (BPA) by condensing acetone with phenol in the presence of a catalyst system containing an acidic heterogeneous catalyst and a catalyst promoter in which at least one organic sulfur-containing compound is present. As a result of the condensation, the effluent from the reactor contains a crude BPA product, usually containing impurities of the acid that is released from the catalyst, water, at least part of the catalyst promoter, and, as a rule, unreacted acetone and phenol. In particular, the present invention provides a simple and effective process for purifying a BPA product that improves its color and thermal stability while minimizing the loss of catalyst promoter present in the reactor effluent.

[0015] For the implementation of the condensation of acetone and phenol in order to obtain BPA in accordance with the present invention can be used in any known reaction system. Typically, acetone and phenol are reacted in the reaction zone in batch or continuous mode at a temperature of from about 20°C to about 130°C, preferably from about 50°C to about 90°C.

[0016] The pressure conditions are not particularly limited, and the reaction may occur at atmospheric pressure, subatmospheric pressure, or above atmospheric pressure. However, it is preferred to carry out the reaction without any external pressure being generated, or at sufficient pressure to allow the reaction mixture to pass through the catalyst bed, or to allow the reaction mixture to flow upward in the vertical reactor, or to keep the contents of the reaction vessel in a liquid state if the reaction takes place at a temperature above the normal boiling point of any ingredient. The pressure and temperature must be set at a level at which the reactants remain in the liquid phase in the reaction zone. The temperature may exceed 130°C, but it should not be so high that any of the ingredients in the reaction vessel decomposes, and it should be so high that the reaction product decomposes or the synthesis of undesired by-products is activated in a significant amount.

[0017] The reactants enter the reaction zone under conditions that provide a molar excess of phenol relative to acetone. For example, the molar ratio of phenol to acetone is preferably at least about 2:1, more preferably at least about 4:1, and up to about 25:1.

[0018] The condensation reaction is carried out in the presence of an acidic heterogeneous catalyst promoted by at least one organic sulfur compound. Suitable catalysts are molecular sieves, partially neutralized and unsolubilized salts of heteropoly acids, and acid cation exchange resins. Preferred condensation catalysts are cation exchange resins, and in particular resins having a cation exchange capacity of at least about 0.5 and more preferably greater than about 4.0 meq/g dry weight. Particularly preferred are sulfonated cation exchange resins such as sulfonated styrene-divinylbenzene a copolymers, sulfonated styrene cross-linked polymers, phenol formaldehyde sulfonic acid resins, benzene formaldehyde sulfonic acid resins, perfluorinated sulfonic acid resins and the like. These include resins sold under trade names such as Amberlite or Amberlyst (Rohm and Haas Co.), DOWEX (Dow Chemical Co.), Permutit QH (Permutit Co.), Chempro (Chemical Process Co.), catalysts under Purolite, Lewatit® (LANXESS Deutschland GmbH), NAFION® (DuPont) and similar materials. Strongly acidic resins based on sulfonated styrene/divinylbenzene copolymers appear to be preferred. Suitable cation exchange resins are prepared using a sulfonated polymerized styrene monomer that is crosslinked using about 1% to about 8% divinylbenzene (resin). Specific examples of suitable sulfonated resins are Amberlyst® 131, Lewatit® K-1221, Purolite® CT-122, Purolite® CT-124, Diaion™ SK104H, Tulsion® 38 and Dowex® 50WX4.

[0019] The condensation catalyst system also contains at least one organic sulfur-containing promoter, which typically contains at least one S-H thiol group. Such thiol promoters may be ionically or covalently attached to the heterogeneous acid catalyst, or they may not be attached to the heterogeneous acid catalyst but added separately to the condensation reaction. Non-limiting examples of linked promoters are mercaptoalkylpyridines, mercaptoalkylamines, thiazolidines, and aminothiols. Non-limiting examples of unbound promoters are alkyl mercaptans such as methyl mercaptan (MeSH) and ethyl mercaptan, mercaptocarboxylic acids such as mercaptopropionic acid, and mercaptosulfonic acids.

[0020] The amount of organic sulfur-containing promoter used in the catalyst system depends on the particular acidic heterogeneous catalyst used. However, as a rule, the organic sulfur-containing promoter is used in an amount ranging from 2 to 30 mol. %, including from 5 to 20 mol. % in terms of acid groups (sulfonic groups) in an acid ion exchanger.

[0021] When the unbound thiol promoter is methyl mercaptan and the carbonyl compound is acetone, 2,2-bis(methylthio)propane (BTMP) is formed in the presence of an acid catalyst. In the presence of a hydrolyzing agent, VMTP dissociates in the reaction zone into methyl mercaptan and acetone, and in this case, acetone condenses with phenol, forming BPA. A suitable hydrolysing agent is water, which may be introduced into any of the feed inlets or directly into the reaction zone, or it may be produced at the site of use by a condensation reaction between the carbonyl compound and the phenolic compound. A molar ratio of water to VMTP catalyst promoter of from about 1:1 to about 5:1 is sufficient to adequately hydrolyze the VMTP catalyst promoter. This amount of water is obtained at the point of use under typical reaction conditions. Thus, no additional water is required to be introduced into the reaction zone, although water may optionally be added if desired.

[0022] Any suitable reactor can be used as the reaction zone. The reaction may take place in a single reactor or in a plurality of reactors connected in series or in parallel. The reactor may be a mixed flow reactor or a plug flow reactor, the reaction may be carried out in a continuous or batch mode, and the reactor may be oriented so as to produce an upward flow or a downward flow. In the case of a fixed bed flow system, the space velocity of the liquid feed mixture entering the reactor is typically between 0.2 and 50 h ^-1 . Although in the case of a suspended bed batch system, the amount of strongly acidic ion exchange resin used is variable depending on the reaction temperature and pressure, it is typically 20 to 100% by weight based on the feed mixture. The reaction time is usually 0.5 to 5 hours.

[0023] The main products of the condensation reaction are the desired isomer of bisphenol (bisphenol-A) and water along with a variety of by-products including other isomers of diphenylolpropane such as 2-(4-hydroxyphenyl)-2-(2-hydroxyphenyl)propane or o ,p-BPA, trisphenols and other impurities such as chromans and indans. In addition, the stream leaving the condensation reactor also contains unreacted phenol and unreacted acetone, as well as at least part of the organic sulfur-containing promoter.

[0024] The raw condensation product stream leaving the reactor also contains trace amounts of polysulfonic acid groups that are released from the sulfonated ion exchange catalyst during the condensation reaction. These polysulfonic acid groups can cause decomposition of the molten BPA product, an increase in the color of the melt, and a decrease in the thermal stability of the BPA product, particularly in applications where a high degree of transparency of the polycarbonate is required. These effects can be mitigated by contacting the crude effluent from the reactor with a base anion exchange resin. However, it has been found that while treatment with a basic anion exchange resin is effective in removing acidic groups from BPA process streams, if those process streams also contain a residual mercaptan promoter, the treatment also converts mercaptan to dimethyl sulfide, dimethyl disulfide, diethyl disulfide, hydrogen sulfide, or other compounds. sulfur. This results in an uneconomical loss of the mercaptan promoter and additional processing steps are required to remove any sulfur compounds.

[0025] To solve this problem, in the processing of the crude stream exiting the condensation reactor, before any contact with the main anion exchange resin, distillation is carried out to remove at least a portion of the catalyst promoter, unreacted acetone, unreacted phenol and water from the crude stream exiting the reactor, and obtaining a residual stream containing phenol, BPA, other diphenylol propane isomers, trisphenols and any other heavy by-products. Distillation of the crude stream leaving the condensation reactor, it is advisable to carry out at a temperature of from 155 to 185°C and an absolute pressure of 50 to 85 kPa.

[0026] At least a portion of the catalyst promoter, unreacted acetone and unreacted phenol, which are removed in the distillation step, is preferably recycled to the condensation reaction.

[0027] The residual stream that remains after the distillation step typically contains less than 1000 ppm. by weight of water, including less than 100 ppm. by weight of water, less than 500 ppm by weight of acetone, including less than 50 ppm. by weight of acetone, and less than 100 ppm. by weight of the sulfur-containing catalyst promoter, including less than 10 hours/million. by weight of the sulfur-containing catalyst promoter. The residual stream is then contacted with a base anion exchange resin to reduce acidic groups that are released from the strongly acidic sulfonated ion exchange condensation catalyst to form a purified stream. The contacting with the base anion exchange resin is carried out at a temperature of 80 to 120° C., for example by passing a downward residual flow through the bed of the base anion exchange resin. A suitable anion exchange resin may be a strong base or weak base anion exchange resin, preferably a weak base anion exchange resin containing primary, secondary or tertiary amino groups. Examples of commercially available base anion exchange resins are Lewatit® MP 62, Amberlyst™ A21, Amberlyst™ A26, and Diaion™ WA-21.

[0028] Any method known to those skilled in the art can be used to recover the desired BPA product from the resulting purified stream. One preferred method for extracting BPA is by crystallization. The crystallization process may be one of several known BPA purification techniques, preferably crystallization of the equimolar adduct with phenol. The resulting crystals are then separated from the mother liquor by filtration or centrifugation. The separated mother liquor is then returned to the condensation reactor. In one embodiment, the mother liquor is separately contacted with a strongly acidic sulfonated ion exchange reaction catalyst to convert impurities, in particular other diphenylol propane isomers, to BPA before the reaction product is returned to the condensation reactor.

[0029] FIG. 1 shows a process according to one embodiment of the present invention, in which fresh acetone is supplied via conduit 11 to a condensing reactor 12 which also recycles acetone, phenol and an organic sulfur-containing promoter via conduit 13. Condensing reactor 12 contains an acidic heterogeneous catalyst, which is preferably is a sulphonated ion exchange resin, and operates under conditions where acetone and phenol react to form condensation reaction products including BPA and water, along with a variety of by-products including other diphenylol propane isomers, trisphenols, and heavy impurities such as chromanes and indans .

[0030] From the condensation reactor 12, an effluent flows out, which contains the products of the condensation reaction, as well as unreacted acetone and phenol and at least part of the catalyst promoter, and enters through conduit 14 to one or more distillation columns 15, which by their action remove (i) a first light stream consisting mainly of unreacted acetone and a catalyst promoter, (ii) a second intermediate stream consisting mainly of water and some unreacted phenol which is present in the effluent, and (iii) a third stream consisting , mainly from unreacted phenol. The first stream (i) and the third stream (iii) are collected and returned to the condensation reactor 12 via conduit 13, while the second light stream (ii) is collected and sent to wastewater treatment (not illustrated) via conduit 16.

[0031] After removing the first light stream (i), the second intermediate stream (ii) and the third stream (iii), the resulting residual stream containing mainly the bisphenol component that is present in the effluent from the condensation reactor and the remaining unreacted phenol, enters through conduit 17 into bed 18 of the base anion exchange resin to remove liberated polysulfonic acid groups. After exiting layer 18, the purified residual stream enters the crystallization unit 19, which receives fresh phenol through pipeline 21. The adduct of phenol with BPA crystallizes selectively in the crystallization unit 19, is separated from the mother liquor by filtration or centrifugation, and enters through pipeline 22 to the final block 23. melt processing. The adduct crystals are melted in a finishing unit 23 to separate the phenol from the BPA, with the phenol returning to the crystallization unit 19 via conduit 24 and the BPA entering the solidifying device 25.

[0032] The mother liquor that remains after the removal of the BPA-phenol adduct is removed from the crystallization unit 19 via conduit 26 and separated into a wash stream 27 and a recycle stream 28, which is returned to the condensation reactor 12. In some embodiments, before returning to the condensation reactor 12, the mother liquor recycle stream is separately contacted with a strongly acidic sulfonated ion exchange reaction catalyst 29 to convert impurities, in particular other diphenylol propane isomers, to the preferred BPA isomer.

[0033] Hereinafter, the present invention will be described more specifically with reference to the following non-limiting examples and the accompanying images in Fig.2-4.

Example 1

[0034] A synthetic mixture consisting of 70 wt. % phenol, 25 wt. % BPA, 2 wt. % water, 2 wt. % ethyl mercaptan and 1 wt. % acetone was obtained to simulate the effluent resulting from the condensation reaction of phenol and acetone in the presence of an ethyl mercaptan promoter, which is an alkyl mercaptan promoter.

[0035] A series of studies were carried out in which 200 g of this synthetic mixture, simulating the effluent from the reactor, was contacted in a closed autoclave with varying amounts of basic anion exchange resin Lewatit® MP 62 WS at a temperature of 90°C, 110°C and 120°C, and with 10 g of basic anion exchange resin Amberlyst™ A26 at 90°C. In each case, the anion exchange resin was washed with demineralized water, the volume of which was ten times the volume of the bed, before testing.

[0036] During each study, samples of the contents of the autoclave were taken at various time points, and these samples were analyzed by gas chromatography (GC) using a flame ionization detector/chemiluminescent sulfur detector (FID/SCD) to identify and quantify any formed sulfide compounds. The results are briefly illustrated in FIG. 2-4 which show that diethyl disulfide (DEDS) was formed during contact with the basic anion exchange resin in the presence of an ethyl mercaptan promoter. In particular, the results show that the concentration of DEDS in the reaction product increased with increasing reaction temperature (FIG. 2) and the amount of anion exchange resin (FIG. 3) in the case of using Lewatit® MP 62 WS anion exchange resin. In FIG. 4 shows that Amberlyst™ A26 anion exchange resin was able to produce more DEDS than Lewatit® MP 62 WS anion exchange resin at the same temperature of 90°C, probably due to the stronger basic active sites present in the first resin. Example 2

[0037] Similar to the study in example 1, a study was conducted in which 200 g of a synthetic mixture consisting of 70 wt. % phenol, 28 wt. % BPA and 2 wt. % ethyl mercaptan, was put into contact with 10 g of the washed anion exchange resin Lewatit® MP 62 WS in an autoclave at 100°C. After conducting a 24-hour study, it was found that the content of ethyl mercaptan in the mixture decreased, while increasing the amount of DEDS. This study demonstrates the loss of the mercaptan promoter to unwanted sulfur compounds if no anion exchange resin is present downstream of the distillation step to remove mercaptan from the condenser effluent.

Example 3

[0038] A synthetic mixture consisting of 70 wt. % phenol and 30 wt. % BPA was obtained to simulate the residual stream that is formed after the distillation of the stream leaving the phenol-acetone condensation reactor to remove water, catalyst promoter and unreacted acetone. 200 g of this synthetic residual mixture was contacted with 10 g of washed Lewatit® MP 62 WS anion exchange resin in an autoclave at 100°C. Within 24 hours, no DEDS was detected in the stream, indicating that no DEDS was formed during contact with the anion exchange resin when the ethyl mercaptan promoter was not present in the mixture.

[0039] The same result (no detectable DEDS) was obtained when the study was repeated with washed Amberlyst™ A26 anion exchange resin.

Examples 4-6

[0040] The study of example 3 was repeated with washed anion exchange resin Lewatit® MP 62 WS, but with a change in the composition of synthetic mixtures consisting of 70 wt. % phenol, 28 wt. % BPA and 2 wt. % water (example 4); 70 wt. % phenol, 29 wt. % BPA and 1 wt. % acetone (example 5); and 70 wt. % phenol, 27 wt. % BPA, 2 wt. % water and 1 wt. % acetone (example 6). In each case, DEDS was not detected in the stream within 24 hours. These examples show that DEDS was not formed during contact with the anion exchange resin in the absence of the ethyl mercaptan promoter and the presence of water and/or acetone in the mixture did not alter these results.

[0041] While the present invention has been described and illustrated by reference to specific embodiments, those of ordinary skill in the art will appreciate that the present invention itself may be subject to variations that need not necessarily be illustrated herein. Then, for this reason, the appended claims should be considered solely for the purposes of determining the actual scope of the present invention.

Claims (19)

1. A method for producing bisphenol-A, and the method includes: (a) reacting acetone and phenol in the presence of a catalyst system containing an acidic heterogeneous catalyst and a catalyst promoter in which at least one organic sulfur compound is present to produce a reactor effluent containing bisphenol-A, water, unreacted acetone, unreacted phenol and at least a portion of a catalyst promoter; (b) distilling at least a portion of the effluent from the reactor to remove water, catalyst promoter and unreacted acetone and obtain a residual stream containing bisphenol A; (c) contacting at least a portion of the residual stream with a base anion exchange resin to obtain a purified stream; And (d) recovering bisphenol-A from the purified stream. 2. The method of claim 1 wherein the acidic heterogeneous catalyst comprises a sulphonated ion exchange resin. 3. The method of claim 1 or 2, wherein the catalyst promoter comprises at least one organic sulfur compound selected from the group consisting of alkyl mercaptans, mercaptocarboxylic acids, mercaptosulfonic acids, mercaptoalkylpyridines, mercaptoalkylamines, thiazolidines, and aminothiols. 4. The method according to any one of paragraphs. 1-3, in which the distillation (b) is carried out at a temperature of 155 to 185°C and an absolute pressure of 50 to 85 kPa. 5. The method according to any one of paragraphs. 1-4, in which the residual stream contains less than 1000 ppm by weight of water, less than 500 ppm by weight of acetone and less than 100 ppm by weight of a sulfur-containing catalyst promoter. 6. The method according to any one of paragraphs. 1-5, further comprising: (e) recycling at least a portion of the catalyst promoter removed in the distillation process (b) to the reaction step (a). 7. The method according to any one of paragraphs. 1-6, in which the introduction into contact (c) is carried out at a temperature of from 80 to 120°C. 8. The method according to any one of paragraphs. 1-7, in which the introduction into contact (c) is carried out by directing down the residual flow through the bed of the main anion exchange resin. 9. The method according to any one of paragraphs. 1-8, in which the anion exchange resin is a weakly basic anion exchange resin containing primary, secondary or tertiary amino groups. 10. The method according to any one of paragraphs. 1-9, wherein recovery (d) comprises crystallization to separate the purified stream into a solid bisphenol-A containing product and a mother liquor stream. 11. The method of claim 10, wherein the mother liquor stream contains isomers of diphenylolpropane other than bisphenol-A, and the method further comprises: (f) contacting the mother liquor with a sulfonated acid ion exchange catalyst under conditions for converting at least some of the other diphenylol propane isomers to bisphenol-A and obtaining an isomerized product stream. 12. The method of claim 11, further comprising: (g) directing at least a portion of the isomerized product stream to reaction step (a).

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