JP3553092B2 - Method for recovering bisphenol-A from production process effluent - Google Patents

Description

[0001]
[Industrial applications]
The present invention relates to a method for synthesizing divalent phenols, and more particularly to a method for recovering bisphenol-A.
[0002]
[Prior art]
The divalent phenol 2,2-bis (p-hydroxyphenyl) propane [commonly referred to as “bisphenol-A”] is prepared by converting 2 moles of phenol and 1 mole of acetone in the presence of an acid catalyst. It is manufactured industrially by condensation. This phenol is present in a molar excess over the stoichiometric amount. Many by-products are formed during the condensation, which contaminate the desired product, bisphenol-A. Among these contaminants carried in the product stream from the condensation reaction zone are water, trace amounts of acidic substances from the catalyst, unreacted phenol and acetone, and some of the bisphenol-A. Isomers are included.
[0003]
In general, in the first step of separating the desired bisphenol-A from the product stream, the product stream is cooled and a 1: 1 addition (combination) of bisphenol-A with the excess phenol present is present. Crystallize and precipitate in the form of a product. The crystallized adduct is separated and washed, and phenol is removed by distillation, extraction or steam stripping. During this separation, the mother liquor obtained by crystallization also contains bisphenol-A mixed with the contaminants already described. Other effluents containing such or similar residues are often produced during various purification steps of bisphenol-A. These effluents are often recycled to the reactor for further condensation reactions, but some are purged or decomposed into phenol, acetone or isopropyl phenol by "cracking", which is valuable. Reagent must be collected.
[0004]
The process of the present invention provides an economical means for recovering bisphenol-A and other valuable residues that are mixed with contaminants in the effluent stream of a manufacturing process without using a cracking operation. . When a cracking operation is used, bisphenol-A is reconverted to its starting materials phenol and acetone.
[0005]
The use of anion exchange resins to remove acidic contaminants from phenol-containing process streams has been published and is known. For example, European Patent Application No. 0,329,075 (Mitsui Toatsu Chemical Co., Ltd.) published on August 23, 1989 contains phenol as a reactant and contains acidic contaminants. A bisphenol-A product stream containing is described. According to this, the product stream is treated with a weakly basic ion exchange resin to remove acidic contaminants before the desired bisphenol-A is separated by distillation. A similar treatment of the bisphenol-A product stream is described in US Pat. No. 4,766,254 to Faler et al. There, the mother liquor obtained from the phenol-bisphenol-A adduct is treated with an anion exchange resin.
[0006]
Summary of the Invention
The present invention comprises a process for recovering bisphenol-A from the mother liquor obtained during the crystallization of a 1: 1 adduct of phenol and bisphenol-A. The mother liquor contains phenol, bisphenol-A, isomers of bisphenol-A, and contaminant by-products of the condensation reaction of phenol and acetone. The method of the present invention comprises:
A. Isomerization of bisphenol-A to bisphenol-A,
B. Removing the acidic impurities by reacting the resulting mixture with a basic ion exchange resin,
C. Separating the bisphenol-A from the acid-free isomerization product.
[0007]
Also, the process of the present invention allows for the recovery of valuable bisphenol-A from any process stream from which a majority of the bisphenol-A has been removed.
[0008]
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS OF THE INVENTION
An industrially important process for producing bisphenol-A is to combine 2 moles of phenol and 1 mole of acetone in the presence of an acid catalyst and a stoichiometric excess of the phenol reactant. Condensing. See, for example, U.S. Patent Nos. 4,766,254 and 4,847,433. A commonly used catalyst is an acidic ion exchange catalyst.
[0009]
Acidic ion exchange resins useful for catalyzing the condensation of phenol with acetone are compositions well known for their preparation. See, for example, the process described in U.S. Pat. No. 3,037,052, which is incorporated by reference. Representative examples of acidic ion exchange resins are resins having a plurality of sulfonic acid groups as pendant groups or ion exchangers of strong acids such as polymers. Examples are sulfonated polystyrene or poly (styrene-divinylbenzene) copolymer and sulfonated phenol-formaldehyde resin. These sulfonated resins are commercially available in gel- and macroreticular types in water-swollen form. Specific examples of commercially available resins include Amberlite IR-120H, Amberlyst 15H, Amberlyst 31, Dowex 50-X-4, and Dowex (Amberlyst). Dowex MSC-1H, Duolite C-26, Permutit QH, Chempro C-2, and Imac C8P / H [where Amberlite ( Amberlite, Amberlyst, Dowex, Duolite, Permutit, Chempro and Imac are US registered trademarks. ]. Other examples of such ion exchangers and methods of making such ion exchangers are described in "The Encyclopedia of Polymer Science and Technology", Vol. 7, pp. 695-708 ("Encyclopedia of Polymer Science and Technology"). 1967) and Third Edition (1981). The exchange capacity of the acidic resin is preferably such that H ⁺ per gram of dry resin is at least 2.0 meq. (Meq.), And 3.0 to 5.5 meq. Exchange capacities in the range of H ⁺ / g (dry resin) are particularly preferred. One preferred catalyst is the Amberlyst® gel type, which is styrene cross-linked with a cross-linkable monomer such as divinylbenzene and the like, which is bound to the aromatic nucleus of the styrene residue. It has a pendant sulfonic acid group. Sulfonation can be performed by the method described in U.S. Pat. No. 2,366,007, which is incorporated by reference.
[0010]
To maximize efficiency (considering that the by-product of the condensation reaction is water), the catalyst is advantageously initially used in a substantially dry (dehydrated) form.
[0011]
The condensation reaction zone may consist of a single reactor or of two or more reactors in series or in parallel. In the case of a reaction zone consisting of multiple reactors, it is appropriate that the phenol is fed entirely to the first reactor and the acetone compound is fed entirely to the first reactor or to the first reactor. It is appropriate to dispense to the first and second and, if used, subsequent reactors.
[0012]
The reaction temperature in the reactor zone can vary from 40 ° C to 95 ° C, with reaction temperatures in the range of 55 to 90 ° C being preferred.
[0013]
The reaction time in the reactor zone can vary and depends on the reaction temperature. For example, the feedstock hourly liquid hourly space velocity (LHSV) can vary over a wide range at rates ranging from 0.2 to 40 liters / hour of feed stream per liter of catalyst.
[0014]
The effluent of the reaction zone is continuously withdrawn and fed to a product bisphenol-A separation system. As already mentioned, this effluent contains unreacted phenol, unreacted acetone, acidic residues of the catalyst, water and isomers of bisphenol-A mixed with the desired bisphenol-A. I have. The isomers of interest are the positional isomers in which the hydroxy group is other than in the pp 'configuration. It is this effluent that is the starting material for the process according to the invention. The effluent may be treated by first cooling to precipitate the crystalline 1: 1 adduct of bisphenol-A and phenol and separating the solid adduct. The remaining mother liquor generally contains significant amounts of residual bisphenol-A.
[0015]
The accompanying figure is a block diagram illustrating the process of an embodiment of the present invention, wherein the starting material is the mother liquor described above.
[0016]
At least a portion of the mother liquor is fed from a storage tank (1) to an "isomerization" reactor (2). The reactor contains a strongly acidic ion exchange resin, such as one selected from the resins previously used as acid catalysts to catalyze the condensation of phenol and acetone. The acid catalyst is present in a catalytic ratio to promote the isomerization of the bisphenol-A isomer. Interestingly, not only is the geometric isomer of bisphenol-A converted to bisphenol-A, but also 4,4 '-(4-hydroxy-m-phenylenediisopropylidene) diphenol [this Are also called "trisphenol" or "BPX-I"], but are structurally similar compounds that are not isomers are also converted to bisphenol-A.
[0017]
In the isomerization reactor, many of the by-product isomers of bisphenol-A, such as 2,4 '-(1-methylethylidene) bisphenol, and some of the compounds of unknown structure are converted to bisphenol-A. A is continuously converted. The mother liquor in reactor (2) is heated to a temperature in the range of about 55-95C to promote isomerization. The progress of the conversion can be followed by conventional analytical techniques that observe the conversion of the isomers.
[0018]
After completion of the isomerization reaction, the effluent of the reactor (2) is passed through a vessel (3) containing a weakly basic ion exchange resin which usually removes traces of acidic impurities.
[0019]
Useful ion exchange resins for this step of the present invention include all known basic resins. Most often they are amine or quaternary ammonium resins which usually contain groups such as dimethylbenzylamino groups or the corresponding methyl-quaternized groups attached to the polymer chain. Amine resins, including amine resins having a pyridyl group, are often preferred. For the purposes of the present invention, amine resins are used in free base form, but quaternary resins having hydroxy anions as counterions can also be used.
[0020]
The preparation of anion exchange resins is generally well known. See, for example, the method described in U.S. Pat. No. 2,632,001 to McMasters et al. In this method, the side chains of poly (vinyltoluene) are chlorinated and then reacted with a tertiary amine in the presence of a polar solvent such as water to form a quaternary ammonium salt. Representative examples of commercially available resins of this type are Amberlite IRA-400, Amberlite IRA-401, Amberlite IRA-402, Amberlite IRA-900, Duolite A-101-D, Duolite ES-111, Dowex 1, Dowex 11, Dowex 21K, and Ionac A-540; and Jimechiruetano - triethanolamine _{(CH 3) 2 -NCH 2 CH} 2 those derived from OH, amber - light (Amberlite) IRA-410, Amba - light (Amberlite) IRA-911, Dow Dowex 2, Duolite A-102-D, Ionac A-550 and Reillex [Amberlite, Duolite, Dowex ) And Ionac are US registered trademarks.
[0021]
Preferred for use in the present invention are weakly basic anion exchange resins containing primary, secondary or tertiary amine groups. Commercially available examples of these products are Amberlite A-21, Dowex 44, Duolite A-7, Ionac A-260, Amberlite. ) IRA-35, Amberlite IRA-68, the last two resins of which are gel types with an acrylic skeleton.
[0022]
The contact of the mixture flowing out of the reactor (2) with the anion exchange resin may be carried out by any convenient means. Generally, it is preferred to pass the purification mixture through a column containing the resin at a temperature in the range of about 45-125 ° C, preferably about 50-75 ° C. Passing the phenol mixture through the column may be upward or downward and is performed for a time sufficient to remove acidic contaminants.
[0023]
Acidic impurities are removed by contacting the anion exchange resin to form a salt therewith.
[0024]
The treatment of the mixture flowing out of the reactor (2) with the weakly basic ion exchange resin may be performed either continuously or batchwise. Generally, the lower the flow rate, the higher the efficiency of removing acidic contaminants. In the case of continuous treatment, the effluent mixture is preferably fed at a flow rate of 2 to 1000 (preferably 3 to 50) kg / hour per kg of weakly basic ion exchange resin. In a batch process, it is preferred to mix the effluent mixture with 1-20% by weight of a weakly basic ion exchange resin for 5-60 minutes.
[0025]
When the resin is used up and loses its efficacy, it can be regenerated, for example, by treatment with a 6-10% aqueous caustic solution. Prior to such treatment, phenol-soluble impurities can be removed by washing with liquid phenol. The presence of such impurities will reduce the regeneration efficiency of the resin. Then wash with water.
[0026]
The effluent from the vessel (3) is then passed through a filter (4) that removes particulate matter (eg, ion exchange resin particles, metal fragments, etc.). This filter (4) removes particles larger than about 5 microns. This is then followed by a series of distillation columns (5, 6, 7), each operating under reduced pressure / temperature conditions that are sequentially (continuously) higher than the previous column, to separate the liquid stream into four fractions. Separate. The distillation column (5) is operated under vacuum and temperature conditions such that a top distillate containing relatively pure phenol (for example, having a purity of 97% or more) is removed. The bottom liquid (bottom) of the distillation tower (5) is supplied to the distillation tower (6). The distillation column (6) is operated under reduced pressure and high temperature conditions such that colored "light" fractions are removed. This light fraction is mainly composed of the residual isomers and chromans of bisphenol-A and other by-products of known / unknown chemical structure. This fraction can be purged from the plant and discarded, or it can be subjected to a recovery process by the process of the present invention or other processes. The bottom liquid of the distillation tower (6) is supplied to the distillation tower (7). The distillation fraction at the top of the distillation column typically contains bisphenol-A having a purity of 60 to 90% depending on the temperature and pressure conditions used. The bottoms of this distillation column (7) contain "heavy residues" purged from the process. These heavy residues can be subjected to further recovery processes (eg, returned to other parts of the bisphenol-A production process, cracked to break down into phenols, and further distilled). , Burn, or use it for another purpose).
[0027]
[Description of Examples]
The following examples illustrate the practice of the present invention. Although this embodiment is considered by the present inventor to be the best embodiment of the present invention, the present invention is not limited to this embodiment.
[0028]
Using the apparatus described above, about 83.3% of phenol and 9.8% of bisphenol-A, 2- (4-hydroxyphenyl) -2- (2-hydroxyphenyl) propane [ie, o , P-bisphenol-A] and a process by-product stream of bisphenol-A containing 2.3% and 4.6% of other by-products at a temperature of 74 ° C. and a flow rate of 20 gpm. From tank (1), a jacketed jacket filled with a bed of sulfonated polystyrene resin (Amberlyst 31, Rhom & Haas, 16500 pounds catalyst on a dry basis) It was continuously passed through the "isomerization" reactor (2). Next, this reaction effluent [phenol 82.5%, bisphenol-A 11.8%, 2- (4-hydroxyphenyl) -2- (2-hydroxyphenyl) propane 1.6. %, Other by-products are 4.1%] at a temperature of 72 ° C., at a temperature of 72 ° C., Amberlyst A-21 weak basicity from Rhom & Haas. The concentration of acidic species was reduced to 2 ppm or less by passing through a container (3) containing 1300 pounds (dry basis) of the anionic resin. The resulting effluent solution was passed through filter (4) to remove particles larger than 2 microns.
[0029]
Next, at least a part of the obtained solution was supplied to a phenol distillation column (5) operated at a pressure of 30 mmHg and a temperature of 218 ° C. Here, phenol was removed as a colorless top material having a purity of about 99%. The bottom liquid contained 1% of phenol. This was continuously fed to the next distillation column (6) operating at a temperature of 224 ° C. and a pressure of about 1-2 mmHg. The overhead stream from this column is yellow-brown and mainly contains the isomers of bisphenol-A, mainly o, p-bisphenol-A (45-50%), 2,2,4-trimethyl-A It consisted of 4- (4-hydroxyphenol) chroman (30-35%), bisphenol-A (2%), and other by-products. It was discarded.
[0030]
The bottom liquid of the tower (6) was supplied to the distillation tower (7) operating at a temperature of 260 to 290 ° C (500 to 550F) and a pressure of 1 to 2 mmHg. The overhead fraction consisted of a slightly colored bisphenol-A with a purity of more than 80%. This was recycled to the bisphenol-A production process. The bottoms contained a heavily colored tar [bisphenol-A less than 30%, heavy phenol process by-products more than 70%], which was discarded.
[0031]
This process allows bisphenol-A and other products to be recycled from the process stream, which would normally be recycled to the first condensation reactor, cracked to phenols, or discarded by combustion. An efficient and low cost method for recovering valuable materials is provided.
[Brief description of the drawings]
FIG. 1 is a block diagram illustrating a specific example of a preferred process of the present invention.
[Explanation of symbols]
1 Mother liquor storage tank,
2 isomerization reactor,
(3) a container filled with a weakly basic ion exchange resin,
4 Filter for particle removal
5, 6, 7 distillation tower.

Claims (3)

Phenol, bisphenol-A, isomers of bisphenol-A, and condensation of phenol and acetone obtained during crystallization of 1: 1 adduct of phenol and bisphenol-A A method for recovering bisphenol-A from a mother liquor containing contaminating by-products of the reaction, comprising:
(A) bringing at least a portion of the mother liquor into contact with a catalyst that isomerizes bisphenol-A to bisphenol-A,
(B) removing acidic impurities by contacting at least a part of the effluent obtained in (A) with a basic ion exchange resin;
(C) The (a) phenol, (b) colored light fraction and (c) bisphenol-A are successively removed from the acid-free effluent from (B) by distillation, whereby bisphenol-A is removed. A method consisting of separating. The method of claim 1, wherein the particulate matter is removed from the acid-free liquid by filtration. Process for the recovery of bisphenol-A from a mixture of bisphenol-A, isomers of bisphenol-A, phenol, acidic impurities and contaminating by-products of the condensation reaction of acetone and phenol And
(A) isomerization of bisphenol-A to bisphenol-A,
(B) removing acidic contaminants from the isomerized product;
(C) filtering the acid-free isomerization product to remove solid particulate matter;
(D) Distillation of substances not containing particulate matter to remove phenol,
(E) distilling the bottom liquid of (D) to remove a colored light fraction,
(F) A method comprising distilling the bottom liquid of (E) to separate bisphenol-A.

Images