WO2011099879A1

WO2011099879A1 - A method to obtain polycarbonate-grade bisphenol a

Info

Publication number: WO2011099879A1
Application number: PCT/PL2011/000010
Authority: WO
Inventors: Maciej Kiedik; Adam SOKOŁOWSKI; Stefan Kubica; Adam Basta; Jerzy MRÓZ; Wiesław HRECZUCH; Małgorzata KAŁĘDKOWSKA
Original assignee: Instytut Inżynierii Materiałów Polimerowych I Barwników; Przedsiębiorstwo Wielofunkcyjne Chemwik Sp. Z O.O.
Priority date: 2010-02-15
Filing date: 2011-02-03
Publication date: 2011-08-18
Also published as: PL212162B1; PL390452A1

Abstract

The present invention relates to a method to obtain polycarbonate-grade Bisphenol A. The Bisphenol A product is obtained by condensation of phenol with acetone in the presence of an acid ion-exchange resin catalyst in three steps in a single reactor and then Bisphenol A is separated from the resulting post-reaction mixture by way of a one-step or two-step suspension crystallization, adduct decomposition, and distilling off of phenol, and acetone is added to the obtained phenol and other phenolic fractions to obtain a concentration in the range 3-10% and contacted at a temperature in the range 50-870C with an acid ion exchange resin after part of its sulfonic groups have been neutralized with 2,2-dimethylthiazolidine or cysteamine, and is sent to the first or second step of suspension crystallization. In one of the embodiments of the invention, the resulting Bisphenol A is subjected to falling-film fractional crystallization.

Description

A method to obtain polycarbonate-grade Bisphenol A

The present invention relates to a method to obtain a high-purity Bisphenol A, suitable for the production of colorless polycarbonates.

The US Patent No. 5315042 discloses a continuous process to obtain Bisphenol A by contacting phenol with acetone in the presence of an acid catalyst, at increased rates of flow through the catalyst, the flow rate being sufficient to result in reduced conversions of acetone, whereby the content of acetone is kept at a high level, leading to high reaction rates and an appropriate increase in the yield of Bisphenol A. Owing to this, the residence time of Bisphenol A in the reaction zone is shorter and the content of undesirable byproducts affecting the coloration of Bisphenol A is lower. The method has the disadvantage of high energy consumption, resulting from low acetone conversions and the corresponding low increase in the concentration of Bisphenol A in the reaction (10-13%), whereby the amount of unreacted raw materials for processing and regeneration per 1 ton of product is very large.

Patent No. 107987 discloses the design of a reactor for carrying out ion- exchanger catalyzed chemical reactions, specifically exothermal reactions, which is in the form of a vertically positioned cylindrical column equipped with filtration elements in the bottom and top sections of the reactor to prevent the ion exchanger from escaping from the reactor, which has a system of filtration slot-nozzles placed in the reactor at a level of from 1/3 to 2/3 of its total height and, below the system of filtration slot nozzles referred to above, there is a partition to reduce the cross- sectional area of the reactor.

International Patent Application No. WO/19302 discloses a process to obtain Bisphenol A in which the reaction is carried out at a phenol-to-acetone ratio by mole of from approx. 4 to approx. 12 in the presence of a modified ion exchange resin catalyst, in a substantially vertical, multistage suspension stripping reaction apparatus. The entire phenol which is necessary for the condensation with acetone is introduced to the reactor column above its top plate. A portion of the entire acetone required is introduced, respectively, to the plate located just below the top plate and to some of or all lower plates, while the inert gas stream flows topwards through a catalyst chamber, to form a liquid-solid suspension for stripping water from the reaction mixture. The method, technically, is very complicated and not suitable for practical applications.

The Polish Patent Application No. P-347705 discloses a process where a two- zone catalyst bed is used in combination with collecting the post-reaction mixture in a manner which is appropriate for such zones and with maintaining a suitable concentration of water and an appropriate temperature in the catalyst bed and with suitable product purification. The method is also characterized by a low increase in the concentration of Bisphenol A in the reaction whereby its energy consumption is too high.

In the process of the invention disclosed in the European Patent No. EP 1809589, initial conversion takes place in a first-step reactor to obtain an increment in the concentration of Bisphenol A by 2-15%, preferably 3-5%, while in the second- step reactors the reaction is carried out so as to obtain a difference in the concentrations of water between the inlet and the outlet of the second-step reactor in the range 0.1-0.5%, preferably 0.1-0.2%), while the difference in the concentrations of acetone between the inlet and the outlet of the second-step reactor should not exceed 2%, preferably 1%, the difference between the concentrations of Bisphenol A at the inlet and the outlet of the reactor should be 1-5%), preferably l-2%>, and the difference in temperatures between the inlet and the outlet of the second-step reactor should not exceed 15°C, preferably 5°C.

According to the method, part of reaction water is removed from the reaction mixture in a continuous manner in the second condensation step. The post-reaction mixture, which is obtained in the second step and which contains not less than 15%>, preferably not less than 23%>, of Bisphenol A is sent to the distillation system to distill off a fraction containing acetone, water, and phenol, obtaining a residue in the form of crude Bisphenol A which contains not more than 5%, preferably not more than 1%, of phenol. The crude Bisphenol A is subjected to separation by distillation or sent to melt-fractional crystallization to obtain an optical grade Bisphenol A and a residue containing Bisphenol A, its isomers and other byproducts. The reaction mixture from the second step of the condensation reaction, optionally, is subjected to suspension crystallization to obtain a suspension of crystalline Bisphenol A-phenol adduct from which the adduct is separated by filtration or centrifugation and is then sent to the distillation system for the separation of Bisphenol A.

In the conventional method referred to above, a post-crystallizaton mother liquor after distilling off any water therefrom is recirculated to the reaction or is sent to separation by distillation. A residue from the . step of separation by distillation or fractional crystallization is diluted by means of a stream of phenol and is subjected to static crystallization, to obtain a Bisphenol A-phenol adduct which is sent to the distillation system along with a stream of post-reaction mixture from the second condensation step. The static crystallization residue, after distilling off any phenol, is sent out from the process. The first-step reactors and, optionally, the second-step reactors, are divided into at least, two reaction sections by not less than three sets of slot nozzles which are placed at various levels in the reactors. There are between one and six second-step reactors for every first-step reactor. The method of the invention enables optical grade Bisphenol A to be obtained at selectivities up to 98%.

On the other hand, according to the European Patent Application No. EP 2090562, Bisphenol A is obtained from phenol and acetone in the presence of an acid ion-exchange resin catalyst in two serially connected reactors, divided into reaction zones by sets of filtration-injection nozzles, placed at not less than three levels, in four steps. The first and second reaction steps are effected in the first reactor in the series. In the first step, the reaction takes places in the top zone of the first reactor with the reaction mixture flowing downwards, while the second step of the reaction takes places in the bottom zone of the first reactor with the reaction mixture flowing upwards. The third step of the reaction takes place in the top zone of the second reactor in the series, with the reaction mixture flowing downwards, to obtain an increment in the concentration of Bisphenol A by 1-10%, while the fourth step takes place in the bottom zone of the second reactor with the reaction mixture flowing upwards.

It is the purpose of the present invention to develop a method to obtain a high-purity Bisphenol A with selectivities above 98% in a manner enabling a high increment in the product concentration to be obtained in a single reactor in order to reduce the plant investment costs.

In the method of the invention, polycarbonate-grade Bisphenol A is obtained from phenol and acetone in the presence of an acid ion-exchange resin catalyst in a single reactor which is divided into three reaction zones: the first top zone, the second middle zone, and the third bottom zone, by means of sets of filtration- injection nozzles which are placed at not less than three levels so that isomerization and rearrangement of byproducts to Bisphenol A as well as condensation of phenol with acetone are effected in the first zone while condensation of phenol with acetone is effected in the second and third zones.

Unexpectedly, it was found that, for the isomerization, rearrangement, and condensation reactions to proceed effectively it is necessary to keep the contents of 4-isopropylphenol and 4-tertbutylphenol in the reaction mixture at levels below 2% and 4%, respectively.

In the method of the invention, a feed mixture which contains phenol and 1- 5% acetone and not more than 2%, preferably not more than 0.5%, of 4- isopropylphenol and not more than 4%, preferably not more than 1%, of 4- tertbutylphenol, is introduced at a temperature in the range 50-75°C to top of the reactor where, in the first step with the reaction mixture flowing downwards through the catalyst bed which is located above the top nozzles, there take place the rearrangement, isomerization, and condensation reactions; in the second reaction step, which is effected in the catalyst bed which is located between the top nozzles and the middle nozzles, a portion of or the entire reaction mixture from the first step flows downwards, or a portion of or the entire reaction mixture from the third step flows upwards, and a portion of or the entire reaction mixture from the first step is sent outside the reactor through its top nozzles and, after being cooled down in a heat exchanger to a temperature in the range 55-75°C and after supplementing the content of acetone to a concentration in the range 2-6%, it is introduced to the third step of the condensation reactio where it flows upwards through the bottom nozzles or downwards via the middle nozzles through the catalyst bed which is located between the bottom nozzles and the middle nozzles, while the final post-reaction mixture from which Bisphenol A is separated is sent outside the reactor through its middle nozzles or its bottom nozzles or its top nozzles.

Before the third reaction zone in the bottom section of the reactor, up to the level of not more than 1.5 m above the upper rim of the bottom nozzles, there are spherical elements 0.5 cm to 35 cm in diameter through which the reaction mixture flows uniformly from the bottom nozzles prior to being contacted with the catalyst which is found in the third reaction zone.

In an embodiment of the invention, in the second step of the reaction, the reaction mixture from the third step of the reaction flowing upwards through the catalyst bed which is located between the middle nozzles and the top nozzles is sent outside the reactor through its top nozzles along with the mixture resulting from the first step of the reaction.

According to another preferable embodiment of the invention, a portion of the reaction mixture resulting from the second or the third step of the reaction is sent through middle nozzles to an external heat exchanger and then, through the bottom nozzles, is fed to the third step of the condensation reaction.

According to yet another preferable embodiment of the invention, a feed stream at a temperature in the range 65-75°C, containing phenol, Bisphenol A, byproducts, 0.5-1.5% water and at least 2% acetone, is fed through additional filtration-injection nozzles which are located inside the catalyst bed above the top nozzles, and then to the catalyst bed which is located above the top nozzles through which the reaction mixture flows downwards.

According to yet another preferable embodiment of the invention, a portion of the feed mixture is introduced to the catalyst bed through its middle nozzles and then, after being combined with the mixture resulting from the third step of the reaction, is sent to the top of the reactor and then outside through its top nozzles as a final post- reaction mixture.

According to another preferable embodiment of the invention, a portion of the feed mixture is fed to the catalyst bed through the bottom nozzles.

The resulting post-reaction mixture, preferably, is contacted with an acid ion exchange resin at a temperature in the range 55-87°C and then with an anion exchanger.

Bisphenol A is separated from the resulting post-reaction mixture by way of one-step or two-step suspension crystallization, filtration, or centrifugation of the Bisphenol A-phenol adduct, adduct decomposition, and distilling off of phenol, whereas a fraction which contains acetone, water, and phenol is distilled off from the post-crystalization mother liquor and separated into components, while the dewatered mother liquor is recirculated to the process of Bisphenol A synthesis and, preferably, acetone is added to the distilled-off phenol and other phenolic fractions to obtain a concentration in the range 3-10% and is contacted with an acid ion exchange resin at a temperature in the range 50-87°C after part of its sulfonic groups have been neutralized with 2,2-dimethylthiazolidine or cysteamine and is sent to the first or the second step of suspension crystallization.

The dewatered post-crystallization mother liquor from the centrifugation or filtration of the Bisphenol A-phenol adduct, preferably, is contacted with a macroporous cation exchange resin at a temperature in the range 55-85°C during a contact time of not less than 0.5 hr.

The dewatered mother liquor resulting from the centrifugation or filtration of the Bisphenol A-phenol adduct, preferably, is introduced into the reactor as a feed.

A fraction containing 4-isopropylphenol and 4-tertbutylphenol, preferably, is removed periodically from the stream of regenerated phenol.

Bisphenol A, preferably, is separated from the resulting post-reaction mixture by distilling off of acetone, water, and phenol.

The Bisphenol A obtained according to the invention, preferably, is subjected to falling-film fractional crystallization.

Example 1

A 85-m³ reactor having its filtration-slot nozzles located at four levels and packed with a Purolite CT 124/3539 solid catalyst bed is filled, from top, with a feed mixture at a temperature of 62°C, containing 67.0% phenol, 3.7% acetone, 12.1% Bisphenol A, 15.3% byproducts, including 0.6% 4-isopropylphenol and 1.2% 4- tertbutylphenol, and 0.3% water, and is contacted downwards with the catalyst which is placed in the first zone of the reactor, above the top nozzles. The reaction mixture from the first reaction zone at a temperature of 78°C, containing 23.4% Bisphenol A, is sent out through the top nozzles to a 15-m tank which is equipped with a heat exchanger, where it is cooled down to a temperature of 71°C, while adding acetone to obtain a content of 3.1 %, and 2/3 of the stream is sent through the bottom nozzles to the third reaction zone where condensation takes place in the catalyst bed which is located between the bottom nozzles and the middle nozzles, and 1/3 of the stream is introduced through additional filtration-slot nozzles which are located above the top nozzles inside the catalyst bed in the first zone of the reactor. From the first reaction zone 10% of the reaction mixture stream, which flows downwards through the catalyst bed which is located between the top nozzles and the middle nozzles, is sent to the second zone and combined with the mixture from the third reaction zone which is sent outside the reactor through the middle nozzles and is then sent to a heat exchanger and, through the bottom nozzles, is recirculated to the third zone of the condensation reaction. ,

In the bottom section of the reactor, before the third reaction zone, up to the level of 850 mm above the upper rim of the bottom nozzles, there are spherical elements having a diameter of 15 cm, through which a reaction mixture flows uniformly from the bottom nozzles prior to being contacted with the catalyst which is found in the third reaction zone.

A portion of the mixture after the third condensation reaction zone is sent outside the reactor through the middle nozzle as a post-reaction mixture containing 29.7% Bisphenol A.

The resulting post-reaction mixture is contacted with the Dowex 55 OA anion exchange resin and is sent to suspension crystallization followed by filtration in order to obtain a Bisphenol A-phenol adduct.

Phenol is distilled off from the adduct in a film evaporator to obtain a crude Bisphenol A with a purity of 97.8%, which is purified by way of falling-film fractional crystallization. The purity of the resulting Bisphenol A is 99.98% and its coloration is below 5 APHA in the molten state.

After removing by distillation any unreacted acetone and reaction water to a content of 0.2%, mother liquor is recirculated to the process along with any recovered phenol and acetone.

Acetone is added to a portion of the stream of recovered phenol to obtain a concentration of 7.5% and is contacted, at a temperature in the range 57-75°C, with the Purolite CT 122 resin after 21% of its sulfonic groups have been neutralized with 2,2-dimethylthiazolidine and the resulting post-reaction mixture, which contains 22.3%) Bisphenol A, is sent to suspension crystallization along with the post-reaction mixture from the third reaction zone. Periodically, a portion of the stream of regenerated phenol is subjected to fractional distillation in order to obtain a suitable composition of the mixture to be fed to the reactor, including the concentration of 4-isopropylphenol (not more than 0.5%) and the concentration of 4-tertbutylphenol (not more than 1%).

Owing to all of the technological operations described herein, the selectivity of the process to obtain Bisphenol A is 99.1%.

Example 2

The post-reaction mixture obtained in Example 1 and containing 29.7% Bisphenol A, is sent to the first step of suspension crystallization and then to centrifugation in order to separate a crude Bisphenol A-phenol adduct which is purified in the second step of suspension crystallization by means of a stream of regenerated phenol which is obtained as described below and then the purified adduct is separated by centrifugation.

The post-crystallization liquor is subjected to distillation to separate water to obtain a content of 0.3% and acetone which, along with the dewatered liquor, is recirculated to the reaction unit and a stream of regenerated phenol, to which fresh acetone is added to obtain a concentration of 8.1% and is contacted, at a temperature gradually increasing from 52°C to 75°C, with the Purolite CT 124 resin having 21% of its sulfonic groups neutralized with cysteamine, and is then sent to the second step of suspension crystallization and the adduct is separated by centrifugation.

The adduct, purified by way of a two-step suspension crystallization, is subjected to distillation in an evaporator and in a steam-stripping column to distill off any phenol and obtain Bisphenol A with a purity of 99.93% and a coloration of 5 APHA with the selectivity of 99.2%.

Claims

1. A method to obtain polycarbonate grade Bisphenol A from phenol and acetone in the presence of an acid ion-exchange resin catalyst, in a single reactor divided into three reaction zones by means of filtration-slot nozzles, wherein the process is carried out in three steps so that part of or the entire feed mixture containing phenol and 1-5% acetone and not more than 2%, preferably not more than 0.5%, of 4-isopropylphenol and not more than 4%, preferably not more than 1%, of 4-tertbutylphenol, is introduced at a temperature in the range 50-75°C, on top of the reactor where rearrangement, isomerization, and condensation reactions take place in the first step while the reaction mixture flows downwards through the catalyst bed which is located above the top nozzles; in the second step, taking place in the catalyst bed which is located between the middle nozzles and the top nozzles, a portion of or the entire reaction mixture from the first step flows downwards or a portion of or the entire reaction mixture from the third step flows upwards, and a portion of or the entire reaction mixture from the first step is sent outside the reactor through the top nozzles and, after being cooled down in a heat exchanger to a temperature in the range 55-75°C and after supplementing the content of acetone to a concentration in the range 2-6%, is sent to the third condensation step where it flows upwards through the bottom nozzles or downwards via the middle nozzle through the catalyst bed which is located between the bottom nozzles and the middle nozzles, and a final post-reaction mixture, from which Bisphenol A is recovered, is sent outside the reactor through the middle nozzle, or the bottom nozzles, or the top nozzles.

2. A method as claimed in Claim 1 wherein, in the second step of the reaction, the reaction mixture from the third reaction step, flowing upwards through the catalyst bed which is located between the middle nozzles and the top nozzles, is sent outside the reactor via the top nozzles together with the mixture resulting from the first reaction step.

3. A method as claimed in Claim 1 wherein a portion of the reaction mixture from the second or third reaction step is sent through the middle nozzles to an external heat exchanger and then, through the bottom nozzles, is sent to the third condensation step.

4. A method as claimed in Claim 1 wherein a feed stream at a temperature in the range 65-75°C, containing phenol, Bisphenol A, byproducts, 0.5-1.5% water and not less than 2% acetone, is fed through additional filtration-slot nozzles which are located inside the catalyst bed above the top nozzles and on to the catalyst bed which is located above the top nozzles through which the reaction mixture flows downwards.

5. A method as claimed in Claim 1 wherein a portion of the feed mixture is sent to the catalyst bed through the middle nozzles and then, together with the mixture resulting from the third reaction step, is sent to top of the reactor and, via the top nozzles, is sent outside as a final post-reaction mixture.

6. A method as claimed in Claim 1 wherein a portion of the feed mitxure is sent to the catalyst bed through the bottom nozzles.

7. A method as claimed in Claim 1 wherein in the bottom section of the reactor before the third reaction zone, up to a level of not more than 1.5 m above the upper rim of the bottom nozzles, there are spherical elements having diameters in the range from 0.5 cm to 35 cm through which the reaction mixture flows uniformly from the bottom nozzles prior to being contacted with the catalyst which is located in the third reaction zone.

8. A method as claimed in Claim 1 wherein the post-reaction mixture obtained is contacted, at a temperature in the range 55-87°C, with an acid ion exchange resin and then with an anion exchanger.

9. A method as claimed in Claim 1 wherein Bisphenol A is separated from the resulting post-reaction mixture by way of a one-step or two-step suspension crystallization, filtration, or centrifugation of a Bisphenol A-fenol adduct, adduct decomposition, and distilling off of phenol, while a fraction containing acetone, water and phenol is distilled off from the post- crystallization mother liquor and separated into components whereas the dewatered mother liquor is recirculated to the Bisphenol A synthesis process.

10. A method as claimed in Claim 8 wherein acetone is added to the distilled-off phenol and to other phenolic fractions to obtain a concentration in the range 3-10% and contacted at a temperature in the range 50-87°C with an acid ion exchange resin after part of its sulfonic groups have been neutralized with 2,2-dimethylthiazolidine or cysteamine and is sent to the first or second step of suspension crystallization.

11. A method as claimed in Claim 8 wherein the dewatered post-crystallization mother liquor from the centrifugation or filtration of the Bisphenol A-phenol adduct is contacted with a macroporous cation exchange resin at a temperature in the range 55-85°C during a contact time of not less than 0.5 hour.

12. A method as claimed in Claims 1 and 8 wherein the dewatered mother liquor resulting from the centrifugation or filtration of the Bisphenol A-phenol adduct is sent to the reactor as a feed.

13. A method as claimed in Claim 1 wherein a fraction containing 4- isopropylphenol and 4-tertbutylphenol is periodically removed from the stream of regenerated phenol.

14. A method as claimed in Claim 1 wherein Bisphenol A is separated from the resulting post-reaction mixture by distilling off any acetone, water, and phenol.

15. A method as claimed in Claims 8 and 13 wherein the resulting Bisphenol A is subjected to falling-film fractional crystallization.