DE2642596A1 - METHOD OF REMOVAL OF COLORED BODIES FROM A RECYCLING STREAM OF A 4,4'-BISPHENOL-A PROCESS - Google Patents

Description

PATENT LAWYERS

DfpWng. P. WIRTH Dr. V. SCHMIED-KOWARZIK DIP. G. DANNENBERG Dr. P. WEINHOLD Dr. D. GUDEL

281134 β FRANKFURT AM MAIN

TELEPHONE (0611)

2870M QR. ESCHENHEIMER STRASSE 38

SK / SK O9300-1-G

Union Carbide Corporation

270 Park Avenue

New / York, N.Y. 10017 / USA

Process for removing color bodies from a recycle stream of a 4,4'-bisphenol-A process

The present invention relates to a method of reduction the content of color bodies in a 4,4'-bisphenol-A recycle stream, by having all or part of the mother liquor recycle stream of the bisphenol-A process with an acidic cation exchange resin which reactivates periodically by washing with a phenol / water mixture ujird.

2,2-bis- (4-hydroxyphenyl) propane (also called '^^' - bisphenol-A ¹¹ ) is prepared by reacting a stoichiometric excess of phenol with acetone in the presence of an acidic catalyst PSS 3 049 569 and 3 242 219 Process for the preparation of 4,4'-bisphenol-A using an acidic cation exchange resin as an acidic catalyst. The effluent from the phenol / acetone reaction contains unreacted starting materials, 4,4'-bisphenol-A, water and by-products. To

709814/1048

Removal of the volatile materials such as acetone, water and some phenol, the effluent is cooled to about 40-50 ° C. to form a 1: 1 molar crystalline adduct of phenol and 4,4'-bisphenol-A. Then the crystalline adduct is separated from the mother liquor and further treated to remove the phenol and obtain practically pure 4,4'-bisphenol-A. After separation from the adduct and the mother liquor is recycled} it contains about 80 % phenol , 4,4'-BiSPhBnOl-A and impurities.

The main component of the impurities is 2,4'-bisphenol-A. If this were the only impurity, it could be the whole Mother liquor recirculated and ground, because the main reaction of phenol with acetone forms an equal mixture of the 4,4'- and 2,4'-isomers. Then there would be no net loss of raw materials to by-products, but there would also be a small but substantial loss Share of other by-products formed. These include trisphenols, higher polyphenols, Dianin's compound and a very low proportion of strongly colored compounds characterized by their intensive absorption of UV light. Would the sarote The concentration of these materials (especially the strongly colored compounds) in the Gradually build up process stream to an unacceptable level. In some processes, part of the mother liquor is therefore continuous deducted. The withdrawn mother liquor is evaporated to obtain most of the phenol contained therein and the rest discarded. This represents a loss of raw material of 0.1 kg / kg of product.

7098U / 1048

GB PS 1 340 869 describes an improvement in which a large part of the withdrawn mother liquor can be recovered. The mother liquor withdrawn is in the presence of a alkaline catalyst subjected to an elevated temperature. This removes a large part of the bisphenols and other contaminants in the mother liquor with formation of phenol and p-isopropenylphenol ("IPP") cleaved, with only a very small amount of an unusable residue being formed. the Phenol and IPP cleavage products (including IPP ditnerem) are processed in a reactor, in urichem phenol and Combine IPP or IPP dimer in the presence of an acidic catalyst to form 4,4'-bisphenol-A. This stream will recombined with the mother liquor recycle stream. Therefore, according to the improved method of the above British patent specification part of the residue from the withdrawn mother liquor, which has hitherto been discarded, is recovered. The loss of Raw material is reduced to about 0.05 kg / kg of product.

It is a characteristic of both of the working methods described above Bisphenol A process that a certain percentage of starting materials Must be discarded in order to build up strong to prevent colored compounds or color bodies. This applies regardless of the quality of the 4,4'-BiSPhBRoIs-A produced. While a 4,4'-bisphenol-A for epoxy purposes has a higher proportion of "2,4'-isomer, trisphenols, etc. can tolerate as such for polycarbonate purposes, color bodies are undesirable in both cases. Even if the amount of color bodies in the process stream is only very small, an inevitable loss of starting material must nonetheless be accepted, which is much greater than

7098U / 1048

S *

the proportion of color formers ^{to the} formation of a discolored

Product to prevent. Hence, there would be a means of selective removal the pigment from the 4,4'-bisphenol-A - \ / ergangsstrorn highly desirable for the purpose of reducing the loss from starting material.

The present invention now provides a method for reducing the content of color bodies in a 4,4'-bisphenol-A recycle stream in which a stoichiometric excess of phenol with acetone in an acidic catalyst containing reaction mixture to form a phenol and 4,4'-phenol '-Bisphenol-A-containing product mixture is reacted, the product ^{mixture being separated into a 4,4 I-} bisphenol-A / phenol adduct and a mother liquor recycle stream and the mother liquor recycle stream being returned to the reaction mixture, which is characterized in that bringing at least a portion of the mother liquor recycle stream into contact with a substantially insoluble acidic cation exchange resin for a sufficient time and at a temperature sufficient to reduce the level of color bodies contained in the mother liquor recycle stream before returning the mother liquor to the reaction mixture. The acidic cation exchange resin is periodically reactivated by washing with a phenol / water mixture.

The present invention is illustrated by the accompanying drawing, the one see ma table is a flow diagram of the two according to the invention Embodiments is.

7098U / 10A8

Out in the drawing and / Ird a stoichiometric excess of phenol and acetone to an example to 65-95 ⁰ C. held reactor 12, which is a sulfonated styrene-divinylbenzene ion-exchange resin contains an acidic catalyst, for example. In the reactor 12, the reaction of phenol with acetone takes place with the formation of 4,4'-bisphenol-A. The product stream flowing out of the reactor 12 contains phenol, 4,4'-bisphenol-A, some unreacted acetone, water and by-products; it flows from reactor 12 to a dehydration unit 14 in which acetone, water and some phenol are removed from the product stream. The dehydrated product stream flows from the device 14 to a crystallization device 16 in which the 4,4'-bisphenol-A / phenol adduct crystals are precipitated by cooling. The mother liquor and adduct crystal slurry flows from the crystallizer 16 to a solid-liquid separator, such as a centrifuge. 18, in which mother liquor and adduct crystals are separated. The 4,4'-bisphenol A product is obtained from the adduct crystals in a known manner (not shown). The mother liquor flows from the centrifuge 18 to a mother liquor storage vessel 22 before being returned to the reactor 12. At least part of the mother liquor flowing out of the centrifuge 18 can be introduced into a recovery reactor 20 ("purge recovery reactor"), in which it is at elevated temperatures, for example 100-3QO ⁰ C, preferably 150-250 ° C, in the presence of a basic catalyst. , is subjected to the bisphenols and other polyphenols present in the mother liquor into phenol and IPP including IPP dimer. to split. Phenol and IPP products

7098U / 1048

from the cleavage reaction are continuously from the recovery reactor 20, e.g., by distillation, and the cleavage reaction product stream 21 becomes the mother liquor recycle stream 19 returned.

Before being returned to the reactor 12, at least part of the flows Mother liquor recycle stream 19 from the mother liquor storage tank 22 to an adsorption column 24 in which it is treated with an acidic cation exchange resin under those described below Conditions is brought into contact. In the adsorption column 24, those present in the mother liquor recycle stream 19 are removed Color bodies removed. In the drawing, the adsorption column 24 is located in the flowing stream between the mother liquor storage container 22 and the reactor 12. An adsorption column 24a can also be located between the centrifuge 18 and the mother liquor storage container 22 where they have some or all of the mother liquor recycle stream 19a that did not pass through the recovery reactor 20. In some cases, e.g. during manufacture of 4,4'-bisphenol-A for epoxy resin purposes, the recovery reactor 20 can be omitted entirely.

The acidic cation exchange resin used in the present invention is a macroreticular cation exchange resin in acidic form. Suitable Ion exchange resins are, for example, sulfonated divinylbenzene-styroic copolymers. The ion exchange resin should be practical

be anhydrous, ie its water content should be in equilibrium with the water content of the mother liquor. Therefore, when the water content of the mother liquor from about 2 wt -.% Is, the ion exchange resin should not be more than about 5-iD wt -% contain water..

7098U / 1Q48

The temperature in the adsorption column is not very critical. Usually, temperatures between etu / a 40-150 C, preferably between etu / a 40-80 ⁰ C is used. At temperatures below about 40 ⁰ C. the phenol in the mother liquor can freeze,

and at temperatures above about 150 ° C., the ion exchange resin can become unstable.

The rate of passage of the mother liquor recycle stream through the adsorption column is not very critical; it can e.g. up to about 15 volumes per hour of the ion exchange resin bed be, u / obei etu / a 1-3 bed volumes / hour are preferred.

The adsorbed color bodies can be desorbed from the acidic cation exchange resin bed by a phenol / water wash. The phenol / water wash can contain about 2-70 wt .-%, preferably about 20-50 wt .- %, V / ater.

In the following examples, the content of color bodies in Mother liquor recycle stream as absorbance of a UU wavelength of 350 nm (microns) using the following procedure became:

1. Purpose

1a The method was used to obtain an absorbance at 350 nm of samples from a bisphenol-A method.

2. Device

2a UV spectrophotometer (Bausch and Lomb Spectzmic 505 or Equivalent) that could be used with 10 cm cells;

2b Matching pair of cylindrical silica cells with 10.0 cm path length j

2c analytical balance;

2d 250 cc Erlenmeyer flasks closed with glass stoppers.

709814/1048

3 «respondents

3a Methanol suitable for spectrophotometry for reactant purposes ("reagent grade");

4 »Procedure

4a The weight of the samples used for the determination depends on the source of the sample. A 1.00 + 0.01 g sample was made for samples from the reaction system, dehydration pre-crystallizer, Mother liquor recirculationstrotB · ■

direction / or a removal system ("purge plant") is used. A 10.0 + 0.1 g sample was used for samples that taken from somewhere in the process after the crystallizer to the final product;

4b Using an analytical balance, the approximate weight (cf. 4a) of the process sample was put into a 250 cc Erlenraeyer flask. To 1 g samples became

10 ecm of methanol, added to 10 g samples of I ^ O ccm of methanol, 'after which there was thorough mixing;

4c Two clean 10.0 cm silica pass cells were filled with methanol filled and into the sample and reference beams of the spectrophotometer given]

4d The wavelength of the spectrophotometer was set to 350 nm, and after waiting 2 minutes for equilibrium, the instrument was set to 0;

4e The cell was removed from the sample chamber of the spectrophotometer removed and discarded the methanol;

4f The cell was filled with sample solution and placed in the sample chamber returned by the spectrophotometer;

After waiting 2 minutes for equilibrium to be established, the absorbance of the sample solution at 350 nm against methanol as a reference either "by recording at the fixed

709814/1048

" 40

Wavelength or recorded by scattering from 320-360 nm}

4h The sample cell was removed, the solution was thrown away and the Cell thoroughly cleaned; then it was refilled with methanol and the instrument again set to 0 at 350 nm. When maintaining the original zero setting, the absorbance value recorded in 4 g was used. If the zero setting was changed, the measurement was repeated starting at 4e.

5. Calculations

A χ 10

5a A * = -

S.W.

It is

A * = one based on a concentration of 10 g sample in 100

ecm of methanol calculated absorbance
A = determined absorbance of the methanolic solution of the sample at 350 nm

SW = weight of the samples in g
Then the value of A * was recorded as the absorbance of the sample.

The following examples in which all percentages, unless stated otherwise, wt -.% Are illustrate the present invention without limiting it.

example \

A glass column of 25 mm diameter was filled with 210 ecm beads of 10-50 mesh size of a phenol-swollen, macroporous sulfonated styrene-divinylbenzene ion exchanger resin. The column was jacketed with temperature-controlled water for heating. The resin was treated with a solution of 20 wt -% of water dissolved in pure phenol, washed.. A total of 16 column volumes of wash solvent

7098 U / 10 4 8

wurden- downwardly through the -.. std "'hydraulically full resin bed at 70 g / 7Q and pumped ⁰ C. The final effluent had an absorbance of 0.5 nm at 350, measured on a solution of 10 g of effluent, diluted with 100 ecm of methanol in a 10 cm cell.

After washing the resin column was made anhydrous by being flushed through with 10 column volumes of anhydrous phenol at 70 g / hr and 7O ⁰ C..

An anhydrous mother liquor (from the centrifuge filtrate), which originated from the condensation of phenol and acetone catalyzed with a cation exchange resin, was used for testing the. Adsorption. ability of the ion exchange resin washed as above is used. This mother liquor had an absorbance of 5.0 and the following composition: 84 % phenol, 10 % 4,4'-BiSPhBnOl-A and 6% impurities.

60 column volume of mother liquor were std downwardly through the ion exchange resin at 80 g / and pumped 7O ⁰ C.. Overall, according to Table 1, a reduction in absorbance of 30 % was obtained.

Table 1

Decreased absorbance at 350 nm of a bisphenol A mother liquor due to treatment with ion exchange resin

Absorbance; 10 g sample, diluted with 100 ecm of methanol, in a 10 cm cell at 350 nm

Charge · '5.0

original discharge 2.0

final discharge 4.5

Combination of the total discharge 3.5

The loaded ion exchange resin was washed under the conditions described above with 8 column volumes of wet phenol (20 % water) to desorb the chromophoric impurities. the

70981 4/1048

- 4-1- -

4t

Absorbance of the total wash effluent corresponded to 18.0 on the base described above.

Example 2

100 g of the anhydrous (15 % water according to Karl Fisher) acidic cation exchange resin described in Example 1 were placed in a glass column with a diameter of 2.5 cm and the resin was mixed with 1000 g of a mixture of 80 % phenol and 20 % water at 70 ^° C. and washed 600 g / h. The resin was then dried by passing 2000 g of anhydrous phenol (0.1 % water) through the d3S bed at 600 g / h. Sixty bed volumes (210 cc / bed volume) of 4,4'-bisphenol-A process mother liquor with an absorbance of 2.5 were treated by passing it down through the bed at a rate of 600 cc / hr. The initial effluent had an absorbance of 1.3, the final of 2.0. The total effluent absorbance was 1.6, which corresponds to a reduction of 36 % .

Table 2 shows the decrease in the adsorbability of the acidic Cation exchange resin as the feed is passed through

the adsorption bed:

Table 2

Color adsorption with adsorbent

Cumulative Absorb.d.Be- Absorbance d.

Charge. ; ccm chic; 350 nm outflow; 350 nm ^ A

1.3 1.2

1.3 1.2

1.6 0.9

1.6 0.9

1.7 0.8 2.0 0.5

620 2.5 3100 I! 5580 Π 8060 II 10540 Il 13020 η

709814/1048

The resin was washed with 1000 g of a mixture of 80 % phenol and 20 % water flowing down the bed at 600 g / hr. The bed was then dried by passing 1000 grams of anhydrous phenol down the bed at 600 grams per hour. 31 bed volumes of common mother liquor from a 4,4'-bisphenol-A process with an absorbance of 2.7 were treated by passing it downwards at 600 g / h. The absorbance of the initial discharge was 1.5 and that of the final discharge was 2.0. The total effluent absorbance was 1.6, a decrease of 41 % .

Table 3 shows the results of a second adsorption experiment after the regeneration of the cation exchange resin as described above. A comparison of Tables 3 and 2 shows that the adsorption capacity of the ion exchange resin through the regeneration stage was completely restored.

Table 3
Color adsorption with regenerated adsorbent

cumulative adsorbance d. Adsorbance d.

Feed; ecm Besch «; 350 ntn out; 350 nm ^ A

1.2 1.3 1.2 1.2 1.0 0.9 0.7

Hehrere 1-g samples of the cation exchange resin described in Example 1 were saturated with the acidic color-bearing impurities, then each sample was immersed for 20 hours at 7O ⁰ C. 4 g of solvent. The ratio of phenol to water

.70 9 81 4/10 A «

600 2.7 3 1.5 1200 n 1.4 3000 η 1.5 3600 Il 1.5 4B00 Il 1.7 6000 Il . 1.8 6600 Il 2.0 example

varied over the wider range shown in the table below. Immediately after immersion, the solvent was decanted from the resins and its absorbance was measured as above in the ultraviolet and visible light range. The data show a maximum color desorption with a water content in the solvent of 20-30 Gern. -%.

709814/10 * 48

(D

N C

BJ CD Xl Ι> H -vT O O) Xl

IO O <N

•H (D X »

N C

(O O Xt ΙΛ

'O) Xt

om

Q) I XtI

· »I.

(D I

0) ·

0) 3

CO (D

τ-Ι Cn!

CO VD CM O Cn! <j-

Ti cm cn en \ o

O · C 3 (D (D x: CJ D-

N -P

CO 0) C el

7-098 U / 1048

After Dekantiaren and prior to measuring the absorbance of the solvent was no approach. Allowed to cool to 25 ⁰ C. 10th It separated into liquid layers, an upper aqueous layer containing 10% phenol and a lower layer containing 70% phenol. The upper aqueous layer is clear and colorless, while the lower layer is deep red-brown in color. This shows that the solubility of the color-bearing impurities in water is low.

The temperature for washing the resin bed with the phenol / water mixture is not very critical. For practical reasons, the temperature is normally not above the boiling point of water. Ice would be impractical to perform washing on etuia 12O ⁰ C., and / would occur eil a desulfonation of the resin. The minimum temperature and the freezing point of the mixture.

The amount of phenol / water mixture required is also not particularly critical. The minimum amount required is around 1-1.5 adsorbent bed volume. The maximum amount u / ird through economic considerations etc. dictated.

The contact time with the washing material is also not decisive. A minimum contact time of about 1 hour is usually used, although longer contact times may be suitable.

709814/1048

Claims (1)

Claims 1.-j Method for removing color bodies from a recycle stream a 4,4'-bisphenol-A process in which a stoichiometric excess of phenol with acetone in a reaction mixture containing an acidic catalyst to form a product mixture containing phenol and 4,4-bis-phenol-A is reacted, the product mixture being converted into a 4,4'-bisphenol-A / Phenol adduct and a mother liquor recycle stream separated and the mother liquor recycle stream to the reaction mixture is returned, characterized in that at least one Part of the mother liquor recycle stream with an adsorbent, which is essentially an insoluble acidic cation exchange resin for sufficient time and temperature to reduce the content of the mother liquor recycle stream The color body contained is brought into contact before the mother liquor is returned to the reaction mixture and periodically removing the adsorbent the adsorbed color bodies with a phenol / water mixture will· 2 · - The method of claim 1, characterized in that the Phanol / water mixture is about 2-70 wt -.% Water, preferably about 20-50 wt .- $! Contains% water - water, and more particularly about 20-30 wt.. The patent attorney: 0 9 814/1048 originally inspected