JPS6352021B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION (Industrial Application Field) The present invention relates to a method for producing 2,2-bis(4-hydroxyphenyl)propane (hereinafter referred to as bisphenol A).

More specifically, in a method for producing bisphenol A from a mixed solution containing phenol and acetone using an acidic ion exchange resin as a catalyst, the above-mentioned mixed solution is brought into contact with a dehydrating agent simultaneously or alternately with the catalyst resin to produce bisphenol. This relates to a method for manufacturing A.

In addition to polycarbonate resins and epoxy resins, bisphenol A has recently been used as a raw material for engine ring plastics, and demand for it has been increasing.

High purity bisphenol A is required for these applications, while an economical manufacturing process is desired.

BACKGROUND OF THE INVENTION Bisphenol A is prepared from acetone and an excess of phenol, with the addition of a co-catalyst such as a sulfur compound when in the presence of an acidic catalyst. The reaction is carried out batchwise or continuously.

Typically, soluble catalysts such as hydrochloric acid or sulfuric acid are used, but removing these catalysts from the reaction mixture requires extensive purification steps, which is not only uneconomical but also removes traces of these acids. If even a small amount remains in the product, the quality of the product will deteriorate.

As a catalyst for producing bisphenol A, a solid acid catalyst can also be used. When a solid acid catalyst is used, a fixed bed or a fluidized bed catalyst bed can be used, and there is no problem of the troublesome removal of the catalyst when a soluble catalyst is used, which facilitates the production operation. .

It is known that an acidic ion exchange resin can be used as a solid acid catalyst (Japanese Patent Publication No. 36-23334).

Even when using an ion exchange resin catalyst, the reaction rate can be increased by using a sulfur-containing compound as a promoter (Japanese Patent Publication No. 19953
issue).

In this case, the mercapto group is fixed to the ion exchange resin as a compound containing a nitrogen group on one side. In these methods, the reaction is carried out in the range of 40 to 100°C using a 4 to 10 times molar excess of phenol relative to acetone, and since it is preferable to have less water in the reaction system, these resins It is dried before use.

The disadvantage of the method for producing bisphenol A from acetone and phenol using an ion exchange resin catalyst is that bisphenol A is stoichiometrically produced regardless of whether or not the ion exchange resin is modified with amines containing mercapto groups. The catalytic ability of the ion exchange resin is reduced by the water produced in almost equimolar amounts.

Even when the reaction is carried out at a molar ratio of phenol to acetone of 6:1, the water produced by the reaction reaches 1.4% or more of the system at an acetone conversion rate of 50%.

Therefore, even if the catalyst resin is dried before use, as the reaction progresses, the activity immediately begins to decrease due to the water produced by the reaction.

In addition, due to the water produced in the reaction, as the amount of water in the system increases as the reaction progresses, the reaction rate gradually slows down. , usually 6~
It is possible to reach an acetone conversion rate of 95% or more in 8 hours, whereas when using an ion exchange resin catalyst, it usually takes 10 hours or more to achieve a conversion rate of 95% or more in a batch method. In a continuous system, it is virtually difficult to reach a conversion rate of 95% or more.

Therefore, when a fixed bed catalyst of ion exchange resin is used, the removal of the catalyst from the system after the reaction and the contamination of the product with residual acid and inorganic substances are reduced, as is the case when using a soluble inorganic acid catalyst. However, the reaction rate decreases due to the water produced by the reaction, and the acetone conversion rate decreases accordingly, resulting in complicated post-treatment steps. Attempting to increase the conversion rate of acetone to 90% or more using the fixed bed method requires a large amount of ion exchange resin, which is not industrially practical.

Therefore, in the method described in Japanese Patent Publication No. 36-23334, it is said that the conversion rate of acetone is about 50%.
Unreacted acetone is separated along with produced water and some phenol, separated in a complicated process that requires a lot of separation energy, and then recovered and used.

However, such a method requires extra energy to separate the excess phenol, making it a less economical process since the resulting reaction product stream can only contain a low concentration of bisphenol A. do not have.

In addition, a method is known in which the concentration of bisphenol A in the reaction product stream is increased by removing acetone, water, and some phenol from a part of the reaction product, and recycling the part to the reaction system. (Japanese Patent Application Laid-Open No. 54-19951) does not disclose a method for recovering unreacted acetone, and it cannot be said to be an economical method since the processing capacity of the reactor is also substantially reduced.

(Problems to be Solved by the Invention) The present invention solves the above-mentioned drawbacks that occur when bisphenol A is produced from a mixed solution containing phenol and acetone using a solid acid, particularly an acidic ion exchange resin, as a catalyst. The purpose of the present invention is to provide a method for producing bisphenol A, which suppresses a decrease in catalyst activity caused by oxidation, improves the acetone conversion rate, and simplifies the post-treatment process.

(Means for solving the problem) The present invention uses an acidic ion exchange resin as a catalyst,
2,2-bis(4-
In the method for producing (hydroxyphenyl) propane, a mixture containing phenol and acetone is
The reaction is carried out by contacting with a mixture of an acidic ion exchange resin and a dehydrating agent for removing water produced by the reaction, or alternatively by contacting the acidic ion exchange resin and a dehydrating agent for removing water produced by the reaction alternately. This is a method for producing 2,2-bis(4-hydroxyphenyl)propane.

The reaction zone may consist of one or two or more reaction zones in series.

When there is only one reaction zone, the dehydrating agent is used simultaneously with the catalyst resin. The ion exchange resin and the dehydrating agent may be used as a mixture, or the reaction mixture may be repeatedly circulated to each layer as separate layers.

When there are two or more reaction zones, the dehydrating agent may be used simultaneously with the catalyst or may exist alternately as dehydrating zones, with each reaction zone and dehydrating zone being separated so as not to disturb the continuous reaction. , regeneration of the catalyst and/or dehydrating agent, and dehydration.

A stream of the mixture containing phenol and acetone is sent to the first reaction zone and, if necessary, to the second reaction zone.
The reaction can be completed in one or more reaction zones. In this case, acetone is preferably sent in portions to two or more reaction zones. This method allows the water produced in each reaction zone to be kept to a low concentration.
Further, it is possible to minimize the undesirable heat generation in the ion exchange resin column, and the amount of by-product impurities can be minimized.

One such embodiment of the present invention is illustrated in FIG. However, actual embodiments are not limited to this.

In FIG. 1, a reaction zone filled with two ion exchange resins and a dehydration zone filled with a dehydrating agent are connected in series, and the dehydration zone consists of two parallel parts.
The two dehydration zones may be used at the same time, or one of them may be used and the remaining zone may be used for another task (cleaning, regeneration, dewatering, etc.). The raw material may be supplied only to the first reaction zone or may be dividedly supplied to the second reaction zone, and it is particularly preferable to supply acetone in divided manner as described above.

In the conventional method, supplying acetone to the rear reactor as described above only increases the amount of unreacted acetone, but according to the method of the present invention, the acetone supplied in this way also has a high conversion rate. can be converted into bisphenol A, and the concentration of bisphenol A in the reaction product liquid can be substantially increased.

As the dehydrating agent used in the method of the present invention, a reactive or adsorption type dehydrating agent can be used. As a reactive dehydrating agent, anhydrous calcium chloride,
Although it is possible to use copper sulfate, calcium sulfate, magnesium sulfate, magnesium oxide, etc. to produce hydrates or dehydration effects such as hydration reactions, phenol-soluble compounds are not preferred because their separation from the reaction product stream becomes complicated.

As the adsorption type dehydrating agent, an inorganic or organic type can be used. As the inorganic adsorbent, silica alumina, synthetic zeolite, molecular sieves, activated carbon for adsorption, molecular sieving carbons, etc. can be used.

As the organic adsorption/dehydration agent, styrene divinylbenzene adsorption resin, weakly acidic ion exchange resin, weakly basic ion exchange resin, etc. can be used. When using a strongly acidic ion exchange resin modified with a mercaptoamine compound as a reaction catalyst, the unmodified strongly acidic ion exchange resin can also be used as a dehydrating agent.

The dehydrating agent may be in the form of powder, granules, pellets or film. Dehydrating agents are used in the form of fluidized beds, fixed packed beds, membrane modules, etc. depending on their shape.

The molar ratio of phenol to acetone is at least 2, and preferably a stoichiometric excess of phenol. A suitable molar ratio is 3-20. When the reaction is carried out in two or more consecutive reactors, it is desirable that the molar ratio of unreacted phenol to acetone be 5 or more in each reaction zone.

The reaction molar ratio is also determined by the temperature of the stream exiting the final reaction stage and the desired bisphenol A concentration.

If the bisphenol A concentration is too high, crystals of adducts with phenol will form in the reaction zone, making continuous operation difficult, while if it is too low, unnecessary labor will be required in the separation step.

Examples of optimal ranges are a phenol to acetone ratio of 20-15 at 60°C and a ratio of 6-4 at 100°C.

When acetone is divided and fed into two or more reaction zones, it is preferred that the molar ratio of unreacted phenol to acetone be 10 or more at the entrance of each reaction zone. This makes it possible to significantly reduce the amount of by-products.

The reaction temperature can be freely selected within a range that does not cause deterioration of the catalyst ion exchange resin. A suitable range is 30~
The reaction zone and dehydration zone can be heated or cooled as required, at a temperature of 120°C, but preferably in the range 50-100°C. Heat exchange may take place between each reaction zone or dehydration zone.

The dehydration zone is periodically or irregularly removed from adsorbed water and reused. The adsorbed water can be removed by known methods such as heating and reduced pressure.

When the catalyst resin and the dehydrating agent are used at the same time, the regeneration treatment and dehydration treatment may be performed at the same time, or only the dehydrating agent may be regenerated after separation. Separation is carried out by known methods such as utilizing the difference in specific gravity and sieving.

It is preferable that the acidic ion exchange resin catalyst used in the method of the present invention is dried before use, but this is not necessarily necessary. The moisture in the catalyst immediately moves to the dehydrating agent or dehydrating agent zone, and the moisture in the catalyst resin becomes small, so the same conversion rate and conversion rate as when using a dry catalyst resin can be continuously achieved.

Bisphenol A obtained by the method of the present invention
Bisphenol A can be economically obtained from a stream containing phenol by known methods, such as removal of phenol by evaporation or crystallization, without going through the complicated steps of recovering acetone and water.

(Function and Effects of the Invention) In the method of the present invention, the water produced in the reaction is immediately removed by the dehydrating agent or dehydrating agent zone, so that the ion exchange resin does not deteriorate. Further, as a side effect of the present invention, impurities produced by the reaction are also removed together with water in the dehydrating agent layer.

Due to this effect, the acidic ion exchange resin can be used continuously for a long period of time without being regenerated.

According to the method of the present invention, as described above, bisphenol A can be economically produced from phenol and acetone at a high conversion rate and high yield.

(Example) Hereinafter, the method of the present invention will be specifically explained using Examples and Comparative Examples.

Example 1 Phenol in a flask with stirrer and reflux
94 parts of acetone, 5.8 parts of acetone, and 5 parts of an acidic ion exchange resin for catalysts (Revacht SC-102, manufactured by Bayer), and further added 10 parts of a dried dehydrating agent (Molecular Sieve 5A, manufactured by UCC), and heated to 80°C. heated to. After 1 hour, the acetone conversion rate reached 75% and 8
After hours the acetone conversion was 96%. The selectivity for bisphenol A was 85%.

Comparative Example 1 A reaction was carried out under the same conditions as in Example 1 without using a dehydrating agent. The acetone conversion rate after 1 hour was 40%,
After 8 hours, the acetone conversion rate was 80% and the bisphenol A selectivity was 83%. 20 in this condition
Even after many hours of reaction, the acetone conversion rate did not reach 95%.

Example 2 The reaction was started under the same conditions as in Comparative Example 1, and 10 parts of the same dehydrating agent used in Example 1 was added after 1 hour. After 8 hours, the acetone conversion rate reached 95%.

Example 3 Three tubular reactors (length 80 cm, inner diameter 2.5 cm) were connected in series, each containing a strongly acidic cation exchange resin with 10% of the exchange capacity partially neutralized with thioethanolamine. All reactors filled with Amberlyst 15 (manufactured by Rohm & Haas) were maintained at 65°C. A replaceable packed bed filled with 100 ml of the dehydrating agent used in Example 1 was placed between each reactor. Phenol and acetone (molar ratio 10:
A feed stream containing 1) was fed continuously from the first reactor at a rate of 3/(catalyst)·HR. 1st
The acetone conversion rate of the effluent from the reactor rose to 75% one hour after the start of the supply, but after the second hour, the conversion rate remained constant at 50% and the water content was reduced to 0.9%.
It contained. The effluent from the first reactor was sent to the second reactor at the same rate after passing through the dehydrating agent layer, but
It contained less than 0.1% moisture. Similarly, the effluent of the second reactor has an acetone conversion of 80
The water content was 0.6%, and after passing through the second dehydrating agent layer, the water content was 0.1% or less. Similarly, the effluent stream from the third reactor was dehydrated with 95% acetone conversion.
It contained only 0.3%. The dehydrating agent in the two dehydrating agent layers was replaced with a new layer every 3 hours. This allowed operation at an acetone conversion rate of 95% for 48 hours. Bisphenol A obtained by removing water and phenol from the effluent of the third reactor has a purity of 97.5%.
It was hot.

Comparative Example 2 The same experiment as in Example 3 was carried out using three tube reactors without a dehydrating agent layer between them. The product stream has a nearly constant composition after 2 hours, with the first reactor effluent containing 0.9% water with 50% acetone conversion;
The second reactor effluent has an acetone conversion of 60%.
It contained 1.1% water. The third reactor effluent contained 1.2% water and the acetone conversion increased only to 65%, and the bisphenol A obtained from this effluent was 96% pure.

[Brief explanation of the drawing]

FIG. 1 is a schematic diagram illustrating one embodiment of the method of the present invention. In the figure, 1 is an acetone supply line, 2 is a phenol and other supply line, 3 is a reaction zone 1, 4 is a dehydration zone, and 5 is a reaction zone 2.

Claims (1)

[Claims] 1. A method for producing 2,2-bis(4-hydroxyphenyl)propane from phenol and acetone using an acidic ion exchange resin as a catalyst,
A mixed solution containing phenol and acetone is brought into contact with a mixture of an acidic ion exchange resin and a dehydrating agent for removing reaction product water, or a mixture of an acidic ion exchange resin and a dehydrating agent for removing reaction product water. 1. A method for producing 2,2-bis(4-hydroxyphenyl)propane, characterized in that the reaction is carried out by contacting alternately with.