Treatment of residual streams from bisphenol production

Abstract

Disclosed is a process for treating a residual stream from bisphenol production, wherein the residual stream includes unreacted phenols, bisphenol isomers, triphenols, organic sulfides, and water. The process comprises contacting at least a portion of the residual stream or reaction products thereof with an acidic catalyst under conditions sufficient to allow acid-catalyzed hydrolysis of organic sulfides within the residual stream to the corresponding mercaptans and produce an effluent stream; and then distilling at least a portion of the effluent stream to recover a distillate product comprising phenols and mercaptans and produce a bottoms product comprising bisphenol isomers and triphenols and having a lower organic sulfide content than the residual stream.

Description

Field of the Invention

[0001] This application is a divisional application of Chinese patent application No. 201880095381.2. The present invention relates to treating a residual stream from bisphenol production, in particular from bisphenol A production, in order to remove and recover sulfur compounds. Background Art

[0002] Bisphenol-A (BPA), also known as 2,2-bis(4-hydroxyphenyl)propane or p,p-diphenylolpropane (p,p-BPA), is an important compound used commercially in the manufacture of polycarbonate, other engineering thermoplastics, and epoxy resins. Polycarbonate applications particularly require high-purity BPA due to the stringent requirements for optical clarity and color in the final application. BPA is commercially produced by the condensation of acetone and phenol, and in fact, BPA production is the largest consumer of phenol. The condensation reaction can occur in the presence of strong homogeneous acids such as hydrochloric acid, sulfuric acid, or toluenesulfonic acid, or in the presence of heterogeneous acid catalysts such as sulfonated ion exchange resins. In recent years, acidic ion exchange resins have become the overwhelming choice as the condensation catalyst for bisphenol production, and strongly acidic sulfonated polystyrene ion exchange resins are particularly useful in this regard.

[0003] Two different techniques for using heterogeneous acid catalysts in bisphenol production predominate in industrial practice. In one technique, a cocatalyst circulates freely within the reactor along with the reaction feed. This serves to enhance the selectivity and / or activity of the reaction. Alkanethiols, such as methyl or ethyl mercaptan, or mercaptocarboxylic acids, such as 3-mercaptopropionic acid, are typically used as the freely circulating cocatalyst in this technique.

[0004] In the second technique for using heterogeneous acid catalysts in bisphenol production, the catalyst is modified by attaching cocatalysts, such as thiazolidinones and aminomercaptans, to some of the acidic sites of the catalyst. For example, the sulfhydryl-promoter groups can be linked to the backbone sulfonate ions of a cation exchange resin via covalent or ionic nitrogen bonds.

[0005] One problem associated with the use of sulfur-containing accelerators in the manufacture of bisphenol is that mercaptans, particularly methyl mercaptan, also react with carbonyl groups and other unsaturated intermediates to form sulfides. These heavy sulfides are present in the reactor product and also in the residue stream remaining after recovery of the desired bisphenol product. Currently, at least a portion of the residue stream is subsequently distilled to recover phenol and water distillates, leaving heavy sulfides in the bottoms stream from the distillation process. This not only increases consumption of the mercaptan accelerator but also contaminates the bottoms stream, complicating disposal and / or further processing of this bottoms stream.

[0006] Therefore, in the manufacture of bisphenol using sulfur-containing promoters, there is a need for a way to remove the sulfide contaminants and recover the mercaptan promoter from the sulfide contaminants from the residual stream remaining after recovery of the desired bisphenol product. SUMMARY OF THE INVENTION

[0007] In one aspect, the present invention is directed to a process for treating a residual stream from bisphenol production, wherein the residual stream comprises unreacted phenol, bisphenol isomers, trisphenols, organic sulfides, and water, and wherein the process comprises:

[0008] (a1) contacting at least a portion of the residue stream or a reaction product thereof with an acidic catalyst under conditions sufficient to allow acid-catalyzed hydrolysis of organic sulfur compounds in the residue stream to corresponding mercaptans and produce an effluent stream; and

[0009] (b1) distilling at least a portion of the effluent stream to recover a distillate product and produce a bottoms product, the distillate product comprising phenols and mercaptans, the bottoms product comprising bisphenol isomers and triphenols and having a lower organic sulfide content than the residual stream.

[0010] In a further aspect, the present invention relates to a method for producing bisphenol A, comprising:

[0011] (a2) condensing acetone with a molar excess of phenol in the presence of a first solid acid catalyst promoted with a mercaptan under conditions effective to produce a first effluent stream comprising bisphenol isomers, unreacted phenol, trisphenols, organic sulfide, and water;

[0012] (b2) recovering bisphenol A from the first effluent stream to leave a residual stream comprising a bisphenol isomer mixture depleted in bisphenol A, unreacted phenol, trisphenols, organic sulfur compounds, and water;

[0013] (c2) contacting at least a portion of the residual stream with a second catalyst under conditions effective to isomerize the bisphenol isomers to bisphenol A and hydrolyze the organic sulfur compounds to the corresponding mercaptans and produce a second effluent stream;

[0014] (d2) dividing the second effluent stream into a recycle stream and a purge stream;

[0015] (e2) supplying the recycle stream to step (a2) or step (b2);

[0016] (f2) distilling the purge stream or a reaction product thereof to recover a distillate product and produce a bottoms product comprising phenol and mercaptans, the bottoms product comprising bisphenol isomers and triphenols and having a lower organic sulfide content than the residual stream; and

[0017] (g2) supplying the distillate product recovered in step (f2) to step (a2).

[0018] In a still further aspect, the present invention relates to a method for producing bisphenol A, comprising:

[0019] (a3) condensing acetone with a molar excess of phenol in the presence of a first solid acid catalyst promoted with a mercaptan under conditions effective to produce a first effluent stream comprising bisphenol isomers, unreacted phenol, trisphenols, organic sulfide, and water;

[0020] (b3) recovering bisphenol A from the first effluent stream to leave a residual stream comprising a bisphenol isomer mixture depleted in bisphenol A, unreacted phenol, trisphenols, organic sulfur compounds, and water;

[0021] (c3) dividing the residual stream into a first portion and a second portion;

[0022] (d3) contacting a first portion of the residual stream with a second catalyst under conditions effective to isomerize the bisphenol isomers to bisphenol A and produce a second effluent stream;

[0023] (e3) recycling at least a portion of the second effluent stream to step (a3) ​​or step (b3);

[0024] (f3) contacting the second portion of the residue stream with a third catalyst under conditions sufficient to allow acid-catalyzed hydrolysis of organic sulfur compounds in the second portion of the residue stream to corresponding mercaptans and produce a third effluent stream;

[0025] (g3) distilling the third effluent stream to recover a distillate product and produce a bottoms product comprising phenols and mercaptans, the bottoms product comprising bisphenol isomers and triphenols and having a lower organic sulfide content than the residual stream and the

[0026] (h3) supplying the distillate product recovered in step (g3) to step (a3).

[0027] This application also relates to the following implementation plans:

[0028] 1. A process for treating a residual stream from bisphenol production, wherein the residual stream comprises unreacted phenol, bisphenol isomers, trisphenols, organic sulfides, and water, and wherein the process comprises:

[0029] (a1) contacting at least a portion of the residue stream or a reaction product thereof with an acidic catalyst under conditions sufficient to allow acid-catalyzed hydrolysis of organic sulfur compounds in the residue stream to corresponding mercaptans and produce an effluent stream; and

[0030] (b1) distilling at least a portion of the effluent stream to recover a distillate product and produce a bottoms product, the distillate product comprising phenols and mercaptans, the bottoms product comprising bisphenol isomers and triphenols and having a lower organic sulfide content than the residual stream.

[0031] 2. The method of embodiment 1, further comprising recycling at least a portion of the distillate product to the bisphenol manufacturing process.

[0032] 3. The method of embodiment 1 or 2, wherein the acidic catalyst comprises an acidic ion exchange resin.

[0033] 4. The process of any of the preceding embodiments, wherein the acidic catalyst comprises a sulfonated acidic ion exchange resin having 2% to 6% cross-linking.

[0034] 5. The process of any one of the preceding embodiments, wherein the recovered mercaptans are alkane mercaptans.

[0035] 6. The process of any of the preceding embodiments, wherein the contacting step (a1) is performed at a temperature of about 60 to 110°C.

[0036] 7. The process of any of the preceding embodiments, wherein the residual stream comprises hydrolyzable organic sulfide in an amount of up to 6,000 ppmwt and water is present in a sufficient amount such that the molar ratio of water to hydrolyzable organic sulfide is at least 4:1.

[0037] 8. The process of any of the preceding embodiments, wherein the residual stream comprises a mother liquor stream from a crystallization step to recover the bisphenol product.

[0038] 9. A method for producing bisphenol A, the method comprising:

[0039] (a2) condensing acetone with a molar excess of phenol in the presence of a first solid acid catalyst promoted with a mercaptan under conditions effective to produce a first effluent stream comprising bisphenol isomers, unreacted phenol, trisphenols, organic sulfide, and water;

[0040] (b2) recovering bisphenol A from the first effluent stream to leave a residual stream comprising a bisphenol isomer mixture depleted in bisphenol A, unreacted phenol, trisphenols, organic sulfur compounds, and water;

[0041] (c2) contacting at least a portion of the residual stream with a second catalyst under conditions effective to isomerize the bisphenol isomers to bisphenol A and hydrolyze the organic sulfur compounds to the corresponding mercaptans and produce a second effluent stream;

[0042] (d2) dividing the second effluent stream into a recycle stream and a purge stream;

[0043] (e2) supplying the recycle stream to step (a2) or step (b2); and

[0044] (f2) distilling the purge stream or a reaction product thereof to recover a distillate product and produce a bottoms product comprising phenol and mercaptans, the bottoms product comprising bisphenol isomers and triphenols and having a lower organic sulfide content than the residual stream.

[0045] 10. The process of embodiment 9, further comprising recycling at least a portion of the distillate product to the condensation step (a2).

[0046] 11. The method of embodiment 9 or 10, wherein the second catalyst comprises an acidic ion exchange resin.

[0047] 12. The method of any one of embodiments 9-11, wherein the second catalyst comprises a sulfonated acidic ion exchange resin having 2% to 6% cross-linking.

[0048] 13. The process of any one of embodiments 9-12, wherein the mercaptan promoter and the recovered mercaptan are alkanethiols.

[0049] 14. The process of any one of embodiments 9-13, wherein the contacting step (c2) is performed at a temperature of about 60 to 110°C.

[0050] 15. The process of any one of embodiments 9 to 14, wherein the purge stream is contacted with a third catalyst under conditions effective to hydrolyze the organic sulfide to the corresponding mercaptan, and the reaction product thereof is subsequently distilled in step (f2).

[0051] 16. The method of embodiment 15, wherein the third catalyst comprises an acidic ion exchange resin.

[0052] 17. The method of embodiment 15 or 16, wherein the third catalyst comprises a sulfonated acidic ion exchange resin having 2% to 6% cross-linking.

[0053] 18. The process of any one of embodiments 15-17, wherein the contacting with the third catalyst is carried out at a temperature of about 60 to 110°C.

[0054] 19. The process of any one of embodiments 9-18, wherein the residual stream comprises hydrolyzable organic sulfide in an amount of up to 6,000 ppmwt and water is present in a sufficient amount such that the molar ratio of water to hydrolyzable organic sulfide is at least 4:1.

[0055] 20. The process of any one of embodiments 9 to 19, wherein the recovery step (b2) comprises crystallization and the residual stream comprises a mother liquor stream from the crystallization.

[0056] 21. A method for producing bisphenol A, the method comprising:

[0057] (a3) condensing acetone with a molar excess of phenol in the presence of a first solid acid catalyst promoted with a mercaptan under conditions effective to produce a first effluent stream comprising bisphenol isomers, unreacted phenol, trisphenols, organic sulfide, and water;

[0058] (b3) recovering bisphenol A from the first effluent stream to leave a residual stream comprising a bisphenol isomer mixture depleted in bisphenol A, unreacted phenol, trisphenols, organic sulfur compounds, and water;

[0059] (c3) dividing the residual stream into a first portion and a second portion;

[0060] (d3) contacting a first portion of the residual stream with a second catalyst under conditions effective to isomerize the bisphenol isomers to bisphenol A and produce a second effluent stream;

[0061] (e3) recycling at least a portion of the second effluent stream to recovery step (a3) ​​or step (b3);

[0062] (f3) contacting the second portion of the residue stream with a third catalyst under conditions sufficient to allow acid-catalyzed hydrolysis of organic sulfur compounds in the second portion of the residue stream to corresponding mercaptans and produce a third effluent stream; and

[0063] (g3) distilling the third effluent stream to recover a distillate product and produce a bottoms product comprising phenols and mercaptans, the bottoms product comprising bisphenol isomers and triphenols and having a lower organic sulfide content than the residual stream.

[0064] 22. The process of embodiment 21, further comprising recycling at least a portion of the distillate product to the condensation step (a3).

[0065] 23. The method of embodiment 21 or 22, wherein the second catalyst comprises an acidic ion exchange resin.

[0066] 24. The method of any one of embodiments 21-23, wherein the second catalyst comprises a sulfonated acidic ion exchange resin having 2% to 6% cross-linking.

[0067] 25. The process of any one of embodiments 21-24, wherein the mercaptan promoter and the recovered mercaptan are alkanethiols.

[0068] 26. The process of any one of embodiments 21-25, wherein the contacting step (d3) is performed at a temperature of about 60 to 100°C.

[0069] 27. The method of any one of embodiments 21-26, wherein the third catalyst comprises an acidic ion exchange resin.

[0070] 28. The method of any one of embodiments 21-27, wherein the third catalyst comprises a sulfonated acidic ion exchange resin having 2% to 6% cross-linking.

[0071] 29. The process of any one of embodiments 21-28, wherein the contacting step (f3) is performed at a temperature of about 60 to 110°C.

[0072] 30. The process of any one of embodiments 21-29, wherein the residual stream in step (b3) comprises hydrolyzable organic sulfide in an amount of up to 6,000 ppmwt and water is present in a sufficient amount such that the molar ratio of water to hydrolyzable organic sulfide is at least 4:1.

[0073] 31. The process of any one of embodiments 21 to 30, wherein the recovery step (b3) comprises crystallization and the residual stream comprises a mother liquor stream from the crystallization. BRIEF DESCRIPTION OF THE DRAWINGS

[0074] Figure 1 illustrates a typical process for processing a residual stream from a bisphenol A manufacturing process.

[0075] Figure 2 A first embodiment of the method disclosed herein is described.

[0076] Figure 3 A second embodiment of the method disclosed herein is described.

[0077] Figure 4 A refinement of the second embodiment of the method disclosed herein is described.

[0078] Figure 5 Shown is the relationship of the first order reaction rate constant for the reduction in 4-methyl-4-methylthio-2-pentanone (MOM) concentration as a function of water concentration in the reaction feed in the presence of a sulfonated strong acid ion exchange resin for a batch reaction of about 750 ppmwt MOM in phenol. Detailed description

[0079] The present invention relates to a process for producing bisphenols by the acid-catalyzed condensation of carbonyl compounds with phenols in the presence of a sulfur-containing promoter. In particular, the present invention provides a simple method for treating the residual stream remaining after recovery of the desired bisphenol product to convert the sulfur-containing by-products of the condensation reaction into mercaptans, which can then be recycled back into the condensation reaction.

[0080] The present invention is applicable to acid-catalyzed condensation reactions between any carbonyl compound reactant and any phenolic compound reactant to produce bisphenol products. Examples of suitable carbonyl compounds are those represented by the formula:

[0081]

[0082] wherein R represents hydrogen or an aliphatic, alicyclic, aromatic or heterocyclic group, including hydrocarbon groups such as alkyl, cycloalkyl, aryl, aralkyl, alkaryl, whether saturated or unsaturated; n is greater than 0, preferably 1 to 3, more preferably 1-2, and most preferably 1; and when n is greater than 1, X represents a bond, or a polyvalent linking group having 1 to 14 carbon atoms, more preferably 1 to 6 carbon atoms, more preferably 1 to 4 carbon atoms; and when n is 1, X represents hydrogen or an aliphatic, alicyclic, aromatic or heterocyclic group, including hydrocarbon groups such as alkyl, cycloalkyl, aryl, aralkyl, alkaryl, whether saturated or unsaturated, with the proviso that X and R are not both hydrogen.

[0083] Suitable carbonyl compounds for use herein include aldehydes and ketones. These compounds typically contain three to fourteen carbon atoms and are preferably aliphatic ketones. Examples of suitable carbonyl compounds include ketones such as acetone, methyl ethyl ketone, diethyl ketone, dibutyl ketone, isobutyl methyl ketone, acetophenone, methyl and amyl ketones, cyclohexanone, 3,3,5-trimethylcyclohexanone, cyclopentanone, 1,3-dichloroacetone, and the like. Acetone is most preferred.

[0084] The carbonyl compound is reacted with a phenolic compound. Suitable phenolic compounds for use herein include phenol and homologues, as well as substitution products of phenol containing at least one substitutable hydrogen atom directly bonded to an aromatic phenolic nucleus. Such groups replacing the hydrogen atom and directly bonded to the aromatic nucleus include halogen groups such as chloro and bromo groups, and hydrocarbyl groups such as alkyl, cycloalkyl, aryl, alkaryl and aralkyl groups. Suitable phenolic compounds include phenol, cresol, xylenol, carvacrol, cumyl alcohol, 2-methyl-6-ethylphenol, 2,4-dimethyl-3-ethylphenol, o-chlorophenol, m-chlorophenol, o-tert-butylphenol, 2,5-xylenol, 2,5-di-tert-butylphenol, o-phenylphenol, 4-ethylphenol, 2-ethyl-4-methylphenol, 2,3,6-trimethylphenol, 2-methyl-4-tert-butylphenol, 2-tert-butyl-4-methylphenol, 2,3,5,6-tetramethylphenol, 2,6-dimethylphenol, 2,6-di-tert-butylphenol, 3,5-dimethylphenol, 2-methyl-3,5-diethylphenol, o-phenylphenol, p-phenylphenol, naphthol, phenanthrol, and the like. Compositions containing phenol are most preferred. Mixtures of any of the above may be used.

[0085] The bisphenol compound obtained by the condensation reaction of a phenolic compound and a carbonyl compound in the process of the present invention is a compound in which the nuclei of at least two phenolic groups are directly connected to the same carbon atom in the alkyl group via a carbon-carbon bond. An illustrative, non-limiting example of a bisphenol compound is represented by the following formula:

[0086]

[0087] wherein R1 and R2 each independently represent a monovalent organic group. Examples of such groups include hydrocarbon groups such as aliphatic, alicyclic, aromatic, or heterocyclic groups, more specifically hydrocarbon groups such as alkyl, cycloalkyl, aryl, aralkyl, and alkaryl groups, whether saturated or unsaturated. Preferably, R1 and R2 each independently represent an alkyl group having 1-2 carbon atoms. Most preferably, the bisphenol compound comprises 2,2-bis(4-hydroxyphenyl)propane, i.e., bisphenol-A (BPA).

[0088] The reaction conditions used to carry out the condensation reaction described above vary with the type of phenolic compound, solvent, carbonyl compound and condensation catalyst selected. Generally, the phenolic compound and carbonyl compound are reacted in a reaction vessel at a temperature ranging from about 20° C. to about 130° C., preferably from about 50° C. to about 90° C., whether in batch or continuous mode.

[0089] There are no particular restrictions on pressure conditions and the reaction can be carried out under atmospheric, subatmospheric, or superatmospheric pressures. However, it is preferred to carry out the reaction under either no externally induced pressure or sufficient pressure to force the reaction mixture over the catalyst bed or upstream in a vertical reactor or to maintain the contents of the reaction vessel in a liquid state if the reaction is carried out at a temperature above the boiling point of any component. The pressure and temperature should be set under conditions that maintain the reactants in the liquid phase within the reaction zone. The temperature may exceed 130°C, but should not be high enough to crack any components within the reaction vessel, nor should it be so high as to crack by-products or promote the formation of significant amounts of undesirable by-products.

[0090] The reactants are introduced into the reaction zone under conditions that ensure a molar excess of the phenolic compound relative to the carbonyl compound. For example, the molar ratio of the phenolic compound to the carbonyl compound is preferably at least about 2:1, more preferably at least about 4:1, and at most about 25:1.

[0091] The condensation reaction is carried out in the presence of an acidic heterogeneous catalyst promoted by at least one organic sulfur-containing compound. Suitable catalysts include molecular sieves, partially neutralized and insoluble salts of heteropolyacids, and acidic cation exchange resins. Preferred condensation catalysts are cation exchange resins and particularly those having a cation exchange capacity of at least about 0.5, and more preferably greater than about 4.0 meq / g dry weight. Sulfonated cation exchange resins are particularly preferred, such as sulfonated styrene-divinylbenzene copolymers, sulfonated cross-linked styrene polymers, phenol-formaldehyde-sulfonic acid resins, benzene-formic acid-sulfonic acid resins, perfluorinated sulfonic acid resins and the like. These include resins sold under the following trade names: Amberlites or Amberlysts (Rohm and Haas Co.), DOWEX (Dow Chemical Co.), Permutit QH (Permutit Co.), Chempro (Chemical Process Co.), catalysts from Purolite, (LANXESS Deutschland GmbH), (DuPont) and the like. Strong acid sulfonated styrene-divinylbenzene copolymer resins are preferred. Suitable cation exchange resins are made from sulfonated polymerized styrene monomers crosslinked with from about 1% to about 8% divinylbenzene (resins). Specific examples of suitable sulfonated resins are 131, K-1221, CT-122, CT-124, Diaion TM SK104H, 38, and 50WX4.

[0092] The condensation catalyst system also comprises at least one organic sulfur-containing promoter, and it contains at least one mercaptan SH group conventionally.Such mercaptan promoter can or ion or covalent bond to heterogeneous acid catalyst or be not attached to heterogeneous acid catalyst, and independently joins in the condensation reaction.The limiting examples of the promoter of combination comprises mercaptoalkyl pyridine, mercaptoalkylamine, thiazolidine and aminomercaptan.The limiting examples of unattached promoter comprises alkyl mercaptan, for example methyl mercaptan (MeSH) and ethyl mercaptan, mercaptocarboxylic acid, for example mercaptopropionic acid, and mercaptosulfonic acid.

[0093] The amount of the organic sulfur-containing promoter used in the catalyst system depends on the specific acidic heterogeneous catalyst used and the condensation process to be catalyzed. However, in general, the organic sulfur-containing promoter is used in an amount of 2 to 30 mol%, for example 5 to 20 mol%, based on the acid groups (sulfonic acid groups) in the acidic ion exchanger.

[0094] When the unbound mercaptan promoter is methyl mercaptan and the carbonyl compound is acetone, 2,2-bis(methylthio)propane (BMTP) is formed in the presence of an acidic catalyst. In the presence of a hydrolyzing agent, BMTP dissociates into methyl mercaptan and acetone within the reaction zone, whereupon the acetone condenses with phenol to form BPA. A convenient hydrolyzing agent is water, which can be introduced directly into any feedstock within the reaction zone or generated in situ via a condensation reaction between the carbonyl compound and the phenolic compound. A molar ratio of water to BMTP catalyst promoter ranging from about 1:1 to about 5:1 is sufficient to fully hydrolyze the BMTP catalyst promoter. This amount of water is generated in situ under typical reaction conditions. Therefore, it is not necessary to introduce additional water into the reaction zone, although water can be added as needed.

[0095] Any suitable reactor may be used as the reaction zone. The reaction may occur in a single reactor or in multiple reactors connected in series or in parallel. The reactor may be a back-mixed or plug flow reactor, and the reaction may be carried out in a continuous or batch mode, and the reactor may be oriented to produce an upward or downward flow. In the case of a fixed bed flow system, the liquid space velocity of the raw material mixture supplied to the reactor is generally 0.2 to 50 hr -1 In the case of a suspended bed batch system, the amount of the strong acid ion exchange resin used, although varying with the reaction temperature and pressure, is generally 20 to 100 wt % based on the raw material mixture. The reaction time is generally 0.5 to 5 hours.

[0096] The main products of the condensation reaction are the desired bisphenol isomer, typically bisphenol A, and water, as well as various by-products, including other bisphenol isomers, such as 2-(4-hydroxyphenyl)-2-(2-hydroxyphenyl)propane or o,p-BPA, triphenols and other impurities, such as chromans and indanes, as well as unconverted phenol and, in some cases, unconverted carbonyl compounds. In addition, the condensation reaction effluent also contains organic sulfides formed by the condensation of the mercaptan promoter with carbonyl groups, carbonyl derivatives, and unsaturated intermediates. One example is 2,2-bis(methylthio)propane (BMTP). Another example of such a sulfide is 4-methyl-4-methylthio-2-pentanone (MOM):

[0097]

[0098] It can be produced by the reaction of mesityl oxide with methyl mercaptan.

[0099] The desired bisphenol product, typically bisphenol A, can be recovered from the condensation effluent using any method known to those skilled in the art. However, generally, the crude effluent from the condensation reaction is fed to a first separator, such as a distillation column, where most of the water and any unreacted carbonyl compounds are removed as an overhead stream and the desired bisphenol product, other bisphenol isomers, unreacted phenolic compounds, and heavy by-products (including organic sulfur compounds) are recovered as a bottoms product. This bottoms product can be fed to a further separator. Although crystallization is a common method for bisphenol separation, any known method for separating the desired bisphenol product from the bottoms product can be used, depending on the desired purity of the bisphenol product.

[0100] The liquid mixture remaining after separation of the desired bisphenol product from the condensation effluent, whether by crystallization or any other method, is referred to herein as the "residue stream." Where the separation is by crystallization, the residue stream is conveniently referred to as the mother liquor. The composition of the residue stream can vary widely but, typically, after distillation to remove and recycle added solvent and optionally partial dehydration, the residue stream contains:

[0101] (a) at most 90 wt%, such as at most 80 wt%, such as at most 75 wt% unreacted phenolic compound and in most cases at least 60 wt%, such as at least 65 wt%, such as at least 70 wt% unreacted phenolic compound;

[0102] (b) at most 30 wt%, such as at most 25 wt%, for example at most 20 wt% of a bisphenol isomer compound depleted in the desired bisphenol isomer, typically bisphenol A, and in most cases at least 10 wt%, such as at least 15 wt%, for example at least 18 wt% of said bisphenol isomer mixture;

[0103] (c) at most 20 wt%, such as at most 16 wt%, for example at most 12 wt% trisphenols and heavy aromatics and in most cases at least 4 wt%, such as at least 6 wt%, for example at least 8 wt% trisphenols and heavy aromatics;

[0104] (d) at most 0.6 wt% (6000 ppmwt), e.g. at most 0.4 wt%, e.g. at most 0.2 wt%, e.g. at most 0.1 wt% organic sulfide and in most cases at least 0.01 wt%, e.g. at least 0.04 wt%, e.g. at least 0.06 wt% organic sulfide; and

[0105] (e) at most 1.0 wt%, such as at most 0.8 wt%, for example at most 0.6 wt% water and in most cases at least 0.2 wt%, such as at least 0.3 wt%, for example at least 0.4 wt% water.

[0106] For process economy purposes, the residue stream undergoes various treatments to recover and recycle unreacted phenolic compounds and bisphenol isomers. Additionally, a portion of the residue stream is typically purged to avoid the accumulation of heavy aromatic compounds in the process recycle loop. The present invention provides a method for converting at least a portion of the organosulfide in the residue stream to mercaptans prior to purging any residue stream, thereby minimizing the loss of mercaptan promoters through the purge and reducing disposal issues for the purge stream.

[0107] In particular, the process disclosed herein comprises contacting at least a portion of the residual stream or its reaction products with an acidic hydrolysis catalyst under conditions sufficient to allow acid-catalyzed hydrolysis of organic sulfides in the residual stream to the corresponding mercaptans and carbonyl compounds. The released carbonyl groups can then react with phenol in the residual stream to form bisphenol isomers and water. The consumption of carbonyl groups and the generation of water facilitate the further conversion of sulfides to mercaptans and carbonyl compounds. A representative example of a hydrolysis reaction is the hydrolysis of 4-methyl-4-methylthio-2-pentanone, which, as described above, can be produced in the methyl mercaptan-promoted manufacture of bisphenol A and which can be hydrolyzed in the presence of an acid catalyst according to the following reaction:

[0108]

[0109] 4-Methyl-4-methylthio-2-pentanone (MOM) Water Isopropenylacetone Methylmercaptan (MeSH)

[0110] Isopropenyl acetone reaches equilibrium with acetone. Furthermore, the two carbonyl compounds can undergo condensation with phenol in the presence of an acidic hydrolysis catalyst to form bisphenol and water.

[0111] While preferred catalysts include acidic ion exchange resins, particularly sulfonated acidic ion exchange resins, any known hydrolysis catalyst can be used to convert the organic sulfur compounds in the residue stream to the corresponding mercaptans. In one embodiment, the hydrolysis catalyst includes an acidic, sulfonated microreticular polystyrene ion exchange resin having 2% to 6% divinylbenzene crosslinking. Suitable conditions for the hydrolysis reaction include a temperature of 60 to 110° C., for example 75 to 95° C., and a reaction time of 1 to 10 hours. -1 The weight hourly space velocity (WHSV) of the reaction mixture is not critical but is typically at least 2:1, such as at least 4:1 or greater, such as at least 20:1. The upper limit of the molar ratio of water to hydrolyzable organosulfide is driven primarily by practical considerations and can be up to 100:1 or greater, such as up to 80:1. Any known reactor configuration can be used for the hydrolysis reaction but in a preferred embodiment the reactor is operated liquid-filled with the feed flowing downwardly through the ion exchange resin catalyst bed.

[0112] The effluent from the hydrolysis reaction is fed to a distillation column, where mercaptans (which are more volatile than the corresponding sulfides) are recovered in an overhead stream along with water and unreacted phenolic compounds. The bottoms product comprises bisphenol isomers, trisphenols, and heavy aromatic products and has a lower organic sulfide content than the residual stream. Typically, the bottoms product contains less than 100 ppm by weight, e.g., less than 10 ppm by weight, of organic sulfides. All or at least a portion of the overhead product can then be recycled, typically without further separation, to the bisphenol production process, particularly the condensation reactor, while at least a portion of the bottoms product can be used in downstream processes, undergo further processing to recover more phenol, acetone, and / or isopropenylphenol, and / or be purified for disposal. In the case of bisphenol A production, suitable operating conditions for the distillation column include temperatures of 160°C to 220°C and pressures of 75 mmHg aq. to 200 mmHg aq.

[0113] In one embodiment of the process of the present invention, the residue stream is divided into a first and a second portion without any initial treatment of the residue stream (except for solvent removal and partial dehydration). The first portion of the residue stream is then supplied to the isomerization reaction zone described below, while the second portion is supplied to the hydrolysis reactor described above. The relative amounts of the first and second portions of the residue stream are not critical, but in some embodiments the second portion comprises at least 1 wt %, e.g., at least 3 wt %, of the total residue stream, but typically does not exceed 6 wt %, e.g., does not exceed 5 wt %, of the total residue stream.

[0114] The isomerization reaction zone used in one embodiment of the process of the present invention may comprise any known acid catalyst that is effective to isomerize a non-equilibrium mixture of bisphenol isomers, particularly a mixture depleted in the desired bisphenol isomer, under the conditions within the isomerization reaction zone. Suitable isomerization catalysts include acidic ion exchange resins, particularly sulfonated acidic ion exchange resins. Suitable isomerization conditions include a temperature of 60 to 100° C., such as 75 to 85° C., and 1 to 10 hours. -1 The effluent from the isomerization reaction zone has a higher content of the desired bisphenol isomer, such as p,p-BPA, than the residual stream and can be recycled to the bisphenol manufacturing process, such as to the condensation reactor or crystallizer, for selective recovery of the desired bisphenol isomer.

[0115] In a further embodiment of the process of the present invention, the entire residual stream is fed to a combined isomerization / hydrolysis reaction zone containing one or more catalysts that are effective to isomerize the non-equilibrium mixture of bisphenol isomers, particularly a mixture depleted in the desired bisphenol isomer, and to hydrolyze the organic sulfur compounds to the corresponding mercaptans under the conditions within the reaction zone. Suitable catalysts for carrying out the combined isomerization / hydrolysis reaction include acidic ion exchange resins, particularly sulfonated acidic ion exchange resins. Suitable isomerization / hydrolysis conditions include a temperature of 60 to 110° C., for example, 80 to 90° C., and a reaction time of 1 to 10 hours. -1 The weight space-time velocity WHSV.

[0116] The effluent from the isomerization / hydrolysis reaction zone has a higher content of the desired bisphenol isomer, such as p,p-BPA, and a lower content of organic sulfur compounds than the residual stream. The effluent is then divided into first and second portions, with the first portion being recycled to the bisphenol manufacturing process, particularly the crystallizer, for selective recovery of the desired bisphenol isomer, and the second portion being supplied to a distillation column. The relative amounts of the first and second portions of the isomerization / hydrolysis effluent are not critical, but in some embodiments, the second portion comprises at least 1 wt %, e.g., at least 3 wt %, of the total effluent, but typically not more than 6 wt %, e.g., not more than 5 wt %, of the total effluent.

[0117] The distillation column receiving the second portion of the isomerization / hydrolysis effluent is operated under conditions such that unreacted phenolic compounds, water, and mercaptans are recovered in an overhead stream, while the bottoms product comprises bisphenol isomers, triphenols, and heavy aromatic compounds and has a lower organic sulfur content than the residual stream. All or at least a portion of the overhead product can then be recycled, typically without further separation, to the bisphenol production process, particularly the condensation reactor, while at least a portion of the bottoms product can be used in downstream processes, undergo further processing to recover more phenol, acetone, and / or isopropenylphenol, and / or be purified for disposal. In the case of bisphenol A production, suitable operating conditions for the distillation column include a temperature of 160° C. to 220° C. and a pressure of 75 mm Hg a to 200 mm Hg a.

[0118] In a further embodiment of the process of the present invention, a second portion of the isomerization / hydrolysis effluent is fed to a further hydrolysis reactor prior to being supplied to the distillation column. The further hydrolysis reactor converts additional organic sulfides present in the isomerization / hydrolysis effluent back into mercaptans for recovery in the overhead of the distillation column.

[0119] Referring to the drawings, in the current prior art, as shown in FIG1 , a crude product stream from a mercaptan-promoted bisphenol A manufacturing process is typically purified in a crystallizer (not shown) to recover the desired bisphenol A, wherein the crude product stream contains phenol, bisphenol A and its isomers, triphenols, and other impurities such as chromans and indanes, water, and sulfides formed from the condensation of the mercaptan promoter with acetone. As shown in FIG1 , the bisphenol A-depleted residual stream (11) remaining after separation of solids from the crystallization effluent and distillation to recover any solvent used in the crystallization step is split into a first portion (12) and a second portion (13). The first portion (12) is then supplied to an isomerization reactor (14) where it is contacted with an acid isomerization catalyst to convert the bisphenol A-depleted bisphenol isomer mixture in the first portion (12) back to equilibrium concentration. The resulting isomerization effluent stream (15) is then recycled to the condensation reactor or crystallizer for recovery of additional bisphenol A.

[0120] The second portion (13) of the residue stream (11) is fed to a distillation column (20), which separates the second portion (13) into a distillate stream (21) containing phenol and water and a bottoms product (22) containing BPA isomers, triphenols, and other impurities, which typically include about 0.01 to about 0.60 wt% organic sulfides.

[0121] exist Figure 2-4 Various embodiments of the present invention are shown in FIG. 1 , wherein like reference numerals are used to denote like components as those shown in FIG. 1 . In a first embodiment of the disclosed method, Figure 2 As shown, the residual stream (11) is split again into a first portion (12) and a second portion (13), wherein the first portion (12) is supplied to the isomerization reactor (14) for contact with the acid isomerization catalyst. However, in this first embodiment of the disclosed process, the second portion (13) of the residual stream is supplied to the hydrolysis reaction zone (25), where the organic sulfur compounds are converted back into carbonyl compounds and mercaptans. The effluent (26) from the hydrolysis reaction zone (25) is then supplied to the distillation column (20) for separation into a distillate stream (21), which now contains mercaptans in addition to phenol and water, and a bottom product (22) containing BPA isomers, triphenols and other impurities, but having less organic sulfur compounds than the residual stream (11).

[0122] Figure 3A second embodiment of the disclosed process is shown in FIG, wherein the entire residue stream (11) is fed to an isomerization / hydrolysis reactor (30) where it is contacted with one or more acid isomerization and hydrolysis catalysts to convert the bisphenol A-depleted bisphenol isomer mixture in the residue stream (11) back to equilibrium concentration and to hydrolyze at least a portion of the organic sulfur compounds to the corresponding mercaptans. The effluent (31) from the isomerization / hydrolysis reactor (30) is then divided into a first portion (32) which is recycled back to the bisphenol A manufacturing process and a second portion (33) which is fed to a distillation column (20).

[0123] exist Figure 4 In a modification of this second embodiment shown, a second portion (33) of the isomerization / hydrolysis reactor effluent is passed through a further hydrolysis reactor (34) before being supplied to the distillation column (20). The reactor (34) contains an acid catalyst, such as an ion exchange resin, which is effective to convert at least a portion of any remaining organic sulfides to the associated mercaptans.

[0124] The present invention is more particularly described with reference to the following non-limiting examples.

[0125] Example 1

[0126] A batch reactor system was used, consisting of a 500-ml three-necked jacketed round-bottom flask, a two-stage condenser to minimize loss of volatile components, and an ethylene glycol circulating bath for reaction mixture temperature control. A thermocouple inserted into the reactor monitored the reaction temperature throughout the experiment. A magnetic stir bar provided constant mixing in the reactor.

[0127] The reactor was initially loaded with 170 g of phenol and 30 g of p,p-BPA isomer. Next, a certain volume of Diaion was washed with deionized water at least 5 times. TMSK104H 4% cross-linked S-DVB ion exchange resin (IER), equal to 5 grams on a dry basis. The IER was then air-dried overnight in a fume hood. Next, the IER was further dried using 1000 ml of phenol in a Soxhlet extractor over a 2.5-hour period before being introduced into the reactor. The phenol / p,p-BPA / IER mixture (initially at room temperature) was heated to 80°C by circulating glycol through the reactor jacket. This step was performed under a nitrogen blanket and with constant stirring of the reactor medium to allow the IER and reaction mixture to equilibrate. During this period, p,p-BPA isomerized to form an equilibrium mixture of o,p-BPA and BPX, as well as impurities typically found in recycle streams of BPA production processes. After approximately 14 to 18 hours, the water content of the conditioned reaction medium was determined by GC / TCD analysis or by KF coulometer and adjusted to 0.50 wt% with deionized water. At least 40 minutes after the final water adjustment, the MOM of 0.16g was added to the reactor to obtain about 800ppmwt when the reaction started. In order to minimize the loss of MOM, the nitrogen purge arriving at the reactor was cut off, and the exhaust pipe of the reactor was clamped and closed in the middle of the whole reaction time period. The duration of the intermittent test was 4 hours, and the timing of the experiment was started when MOM was added. Before adding MOM, the starting sample was taken out from the reactor. The syringe injected by the septum was used to sample the reaction mixture. After adding MOM, the reactor was sampled at intervals of 1 hour. Each sample was labeled (0 to 4) and prepared according to the internal standard scheme for HPLC analysis and sulfur species formation (GC / SCD). The MOM concentration of each sample in ppmwt is shown in Table 1. Based on phenol, BPA, the initial MOM concentration of the interpolation weight calculation of water and MOM is calculated.

[0128] Examples 2 to 6

[0129] For these examples, the batch reaction described in Example 1 was repeated using the same conditions except that the water concentration measured in the sample taken immediately before MOM addition (Sample 0) was varied as shown in Table 1.

[0130] Table 1

[0131]

[0132] Examples 7 to 10

[0133] For these examples, the batch reaction described in Example 1 was repeated using the same conditions except that the reaction temperature was increased to 95°C for Examples 7 and 8, and decreased to 65°C for Examples 9 and 10.

[0134] Example 11

[0135] For Example 11, the batch reaction described in Example 1 was repeated using a volume of 4% cross-linked S-DVB ion exchange resin equivalent to 10 grams on a dry weight basis instead of 5 grams.

[0136] Examples 12 to 15

[0137] For Examples 12-15, 5 g dry weight of 2% cross-linked S-DVB ion exchange resin ( The batch reaction described in Example 1 was repeated using CT-122) instead of 4% by volume of cross-linked S-DVB ion exchange resin.

[0138] Example 16

[0139] For Example 16, the batch reaction described in Example 1 was repeated using 1.345 grams of MOM to obtain a starting concentration of about 6,300 ppmwt with a water concentration of 0.29 wt%.

[0140] The measured MOM concentrations for Examples 1 to 6 can be plotted against reaction time to show that the hydrolysis reaction rate is essentially first order relative to MOM. The experimental reaction rate constant k is then calculated as shown in the last column of Table 1. exp .exist Figure 5 , the experimental reaction rate constants for Examples 1-6 are plotted as a function of the initial water concentration, which shows that the MOM reaction rate constant is inversely proportional to the square of the initial water concentration. Figure 5 This indicates that the effective acidity of the ion exchange resin has a strong influence on the MOM reaction rate and that the hydrolysis reaction rate is not limited by water concentration as long as it is present in stoichiometric excess. The relationship between the initial water concentration and the experimental reaction rate constants in Examples 1-6 was used to calculate the adjusted experimental reaction rate constant k at a nominal initial water concentration of 0.5 wt%. 0.5w％ Based on k of Examples 1-6 0.5w％ The expected value is 0.0125. Table 2 shows the adjusted experimental rate constants for Examples 1-16. The value in the rightmost column is R, the adjusted experimental rate constant k 0.5w％ To Figure 5 For the temperatures, catalyst types, and catalyst loading rates used in Examples 1-6, the examples with R values ​​greater than 1 had reaction rates that were higher than the water-adjusted rate relationship. For the temperatures, catalyst types, and catalyst loading rates used in Examples 1-6, the examples with R values ​​less than 1 had reaction rates that were lower than the water-adjusted rate relationship.

[0141] Table 2

[0142]

[0143] Example 16 demonstrates efficient hydrolysis of MOM up to 6,300 ppmwt concentration at a 3.72:1 molar ratio of water to hydrolyzable organosulfide. Table 3 shows the MOM concentration as a function of time for Example 16. The concentration of methyl mercaptan (MeSH) was increased to a stoichiometrically equivalent concentration.

[0144] Table 3

[0145] Reaction time, min 0 60 120 180 240 [MOM],ppmwt 6,327 124 6.5 0 0 [MeSH],ppmwt 0 2,674 1,942 2,360 2,092

[0146] While the present invention has been described and illustrated with reference to particular embodiments, those skilled in the art will appreciate that the invention is susceptible to variations not necessarily illustrated herein. For this reason, reference should be made solely to the appended claims for purposes of determining the true scope of the invention.

Claims

1. A method for producing bisphenol A, the method comprising: (a2) condensing acetone with a molar excess of phenol in one or more condensation reactors in the presence of a first solid acid catalyst promoted with a mercaptan under conditions effective to produce a first effluent stream comprising bisphenol isomers, unreacted phenol, trisphenols, organic sulfide, and water; (b2) recovering bisphenol A from the first effluent stream to leave a residual stream comprising a bisphenol isomer mixture depleted in bisphenol A, unreacted phenol, trisphenols, organic sulfide, and water, wherein the residual stream includes hydrolyzable organic sulfide in an amount of at least 0.04 wt % and at most 6,000 ppmwt; (c2) contacting at least a portion of the residual stream with a second catalyst in a second reactor under conditions effective to isomerize the bisphenol isomers to bisphenol A and hydrolyze the organosulfide to the corresponding mercaptans and produce a second effluent stream; (d2) dividing the second effluent stream into a recycle stream and a purge stream; (e2) supplying the recycle stream to step (a2) or step (b2); (f2) contacting the purge stream with a third catalyst in a third reactor under conditions sufficient to enable acid-catalyzed hydrolysis of organic sulfur compounds in the purge stream to corresponding mercaptans and produce a third effluent stream; and (g2) distilling the third effluent stream to recover a distillate product and to produce a bottoms product, the distillate product comprising phenol and mercaptans, the bottoms product comprising bisphenol isomers and triphenols and having a lower organic sulfide content than the residual stream.

2. The process of claim 1, further comprising recycling at least a portion of the distillate product to the condensation step (a2).

3. The process of claim 1 or 2, wherein the second catalyst comprises an acidic ion exchange resin.

4. The process of any one of claims 1 to 3, wherein the second catalyst comprises a sulfonated acidic ion exchange resin having 2% to 6% cross-linking.

5. The process of any one of claims 1 to 4, wherein the mercaptan promoter and the recovered mercaptan are alkanethiols.

6. The process of any one of claims 1 to 5, wherein the contacting step (c2) is performed at a temperature of 60 to 110°C.

7. The process of any one of claims 1 to 5, wherein the purge stream is contacted with a third catalyst under conditions effective to hydrolyze the organic sulfide to the corresponding mercaptan, and the reaction product thereof is subsequently distilled in step (f2).

8. The method of claim 7, wherein the third catalyst comprises an acidic ion exchange resin.

9. The process of claim 7 or 8, wherein the third catalyst comprises a sulfonated acidic ion exchange resin having 2% to 6% cross-linking.

10. The process of any one of claims 7 to 9, wherein the contacting with the third catalyst is carried out at a temperature of from 60 to 110°C.

11. The process of any one of claims 1 to 10, wherein the residual stream comprises hydrolyzable organic sulfide in an amount of at least 0.06 wt% and at most 6,000 ppmwt and water is present in a sufficient amount to provide a molar ratio of water to hydrolyzable organic sulfide of at least 4:

1.

12. The process of any one of claims 1 to 11, wherein the recovery step (b2) comprises crystallization and the residual stream comprises a mother liquor stream from the crystallization.

13. A method for producing bisphenol A, the method comprising: (a3) condensing acetone with a molar excess of phenol in one or more condensation reactors in the presence of a first solid acid catalyst promoted with a mercaptan under conditions effective to produce a first effluent stream comprising bisphenol isomers, unreacted phenol, trisphenols, organic sulfide, and water; (b3) recovering bisphenol A from the first effluent stream to leave a residual stream comprising a bisphenol isomer mixture depleted in bisphenol A, unreacted phenol, trisphenols, organic sulfide, and water, wherein the residual stream includes hydrolyzable organic sulfide in an amount of at least 0.04 wt % and at most 6,000 ppmwt; (c3) dividing the residual stream into a first portion and a second portion; (d3) contacting a first portion of the residual stream with a second catalyst under conditions effective to isomerize the bisphenol isomers to bisphenol A and produce a second effluent stream; (e3) recycling at least a portion of the second effluent stream to the condensation step (a3) ​​or the recovery step (b3); (f3) contacting the second portion of the residue stream with a third catalyst in a further reactor under conditions sufficient to allow acid-catalyzed hydrolysis of the organosulfide in the second portion of the residue stream to the corresponding mercaptan and produce a third effluent stream; and (g3) distilling the third effluent stream to recover a distillate product and produce a bottoms product comprising phenols and mercaptans, the bottoms product comprising bisphenol isomers and triphenols and having a lower organic sulfide content than the residual stream.

14. The process of claim 13, further comprising recycling at least a portion of the distillate product to the condensation step (a3).

15. The method of claim 13 or 14, wherein the second catalyst comprises an acidic ion exchange resin.

16. The process of any one of claims 13-15, wherein the second catalyst comprises a sulfonated acidic ion exchange resin having 2% to 6% cross-linking.

17. The process of any one of claims 13 to 16, wherein the mercaptan promoter and the recovered mercaptan are alkanethiols.

18. The process of any one of claims 13 to 17, wherein the contacting step (d3) is performed at a temperature of 60 to 100°C.

19. The method of any one of claims 13-18, wherein the third catalyst comprises an acidic ion exchange resin.

20. The process of any one of claims 13-19, wherein the third catalyst comprises a sulfonated acidic ion exchange resin having 2% to 6% cross-linking.

21. The process of any one of claims 13 to 20, wherein the contacting step (f3) is performed at a temperature of 60 to 110°C.

22. The process of any one of claims 13 to 21, wherein the residual stream in step (b3) comprises hydrolyzable organic sulfides in an amount of at least 0.06 wt% and at most 6,000 ppmwt and water is present in a sufficient amount so that the molar ratio of water to hydrolyzable organic sulfides is at least 4:

1.

23. The process of any one of claims 13 to 22, wherein the recovery step (b3) comprises crystallization and the residual stream comprises a mother liquor stream from the crystallization.

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