JP3419022B2 - Method for producing bisphenol A - Google Patents

Description

Detailed Description of the Invention

[0001]

TECHNICAL FIELD The present invention relates to a method for producing bisphenol A from an adduct of bisphenol A and phenol. More specifically, the present invention relates to a method capable of stably producing bisphenol A by distilling an adduct of bisphenol A and phenol to prevent clogging of a process pipe when producing bisphenol A.

[0002]

2. Description of the Related Art Bisphenol A, which corresponds to 2,2-bis (4-hydroxylphenyl) propane, is widely used as a main raw material for epoxy resins, polycarbonate resins, etc. High-purity bisphenol A is required for quality improvement. As one of the special applications, for example, in polycarbonate resins, the demand for optical materials has increased in recent years, and it is required to supply bisphenol A which is more colorless and higher in purity than ever before.

As a method for industrially producing and purifying bisphenol A, there is a method utilizing the property that bisphenol A forms an adduct with phenol and crystallizes in a phenol solution of bisphenol A. That is, bisphenol A is produced from phenol and acetone as main raw materials in the presence of an acid catalyst. After removing the catalyst, unreacted acetone, reaction product water and a part of unreacted phenol in the reaction product, a crystallization operation is added to this to obtain a bisphenol A phenol solution containing crystals of the bisphenol A phenol adduct. It is a method of obtaining a slurry, separating the phenol adduct of bisphenol A from this slurry, and then removing the phenol.

A distillation method is one of the methods for removing phenol from a phenol adduct of bisphenol A.
As one of the methods, there is a method in which phenol is distilled off from the top of the column by distillation of the adduct to obtain bisphenol A from the bottom of the column. A problem in adopting this method is the occurrence of blockage of bisphenol A in the process pipe following the tower top. The phenol gas distilled in the distillation column contains bisphenol A due to the gas-liquid equilibrium relationship or the phenomenon of entrainment of the concentrated bisphenol A liquid after phenol evaporation. Due to this gas-liquid equilibrium relationship, the phenol gas containing bisphenol A has a high dew point, and when the temperature drops a little, it immediately reaches the dew point and the liquid with a high bisphenol A concentration is partially condensed. Since it is high, it solidifies immediately below the freezing point, which causes clogging of the piping. On the other hand, the droplets of bisphenol A entrained in the phenol gas easily attach to the inner surface of the pipe due to gravity drop or scattering collision, and solidify to cause clogging.

Japanese Unexamined Patent Publication (Kokai) No. 4-13640 discloses a technique of spraying a part of the phenol condensate in this process from the upper part of the condenser to prevent clogging of the condenser itself. It is a thing. Moreover, it is a problem peculiar to the vertical condenser, and the problem of clogging due to solidification of bisphenol A between the distillation column and the condenser, particularly in the pipe near the top of the distillation column, which is the subject of the present invention, cannot be solved.

[0006]

SUMMARY OF THE INVENTION Therefore, the object of the present invention is to remove phenol from a phenol adduct of bisphenol A by a distillation method to produce bisphenol A, and to introduce it into a process pipe connected to the top of a distillation column. This is a method for efficiently preventing the blockage of the pipe due to the fixation of bisphenol A.

[0007]

As a result of intensive studies to solve this problem, the present inventors have found that the process pipe between the distillation column and the condenser, particularly the process pipe near the top of the distillation column. If you spray the phenol-containing liquid inside,
The inventors have found that bisphenol A can be prevented from sticking and have completed the present invention. That is, the gist of the invention is a method for producing bisphenol A by introducing an adduct of bisphenol A and phenol into a distillation column and distilling phenol vapor from the upper part of the distillation column through a process pipe to produce bisphenol A. Distill off the phenol-containing liquid in the vicinity of the distillation column
Bisphenol A while spraying in the process pipe of
In the manufacturing method. Hereinafter, the content of the present invention will be described in detail.

The distillation column according to the present invention is not limited to the purpose of fractionating a large number of components in the column, and may be an evaporator. Hereinafter, unless otherwise specified, in the present invention, the distillation column is meant to include an evaporator.

The adduct of bisphenol A and phenol is usually introduced into the distillation column in a molten liquid state. The liquid temperature after the introduction is 135 to 200 ° C., more preferably 14
It is kept at 0 to 190 ° C. Since the high-concentration phenol solution of bisphenol A may reach a freezing point of 125 to 157 ° C., it is not preferable to set it below 135 ° C. On the contrary, it is not preferable to raise the temperature so as to exceed 200 ° C., because decomposition and coloring of bisphenol A become a problem. It is preferable to operate under a reduced pressure of 1 to 200 Torr in the distillation column. If it is less than 1 Torr, the distillation column and the vacuum generator become large, which is costly and not preferable. On the other hand, if it exceeds 200 Torr, the operating temperature rises and the decomposition and coloring of bisphenol A become a problem, which is not preferable.

By the above-mentioned distillation operation, a phenol gas whose main component is phenol is distilled from the top of the column, and a liquid whose main component is bisphenol A is obtained from the bottom of the column.
Phenol gas containing phenol as the main component from the top of the tower reaches the condenser through the process pipe, and the gas is recovered as a condensate. However, due to the gas-liquid equilibrium relationship, the phenol gas is slightly bisphenol A vapor. In addition, the droplets of bisphenol A are included due to the droplets accompanying the evaporation of phenol gas. These tend to reach the dew point due to a slight decrease in the temperature of the inner wall of the process pipe, and fine droplets of bisphenol A are likely to stick to the wall surface due to collision with the inner wall of the pipe.

The present invention has as its content the method of spraying the phenol-containing liquid in the process pipe in such a state, particularly in a place near the top of the tower. The method of spraying is not particularly limited, but the bisphenol A in the phenol gas in the process pipe is absorbed in advance and the high-concentration bisphenol A condensate on the pipe is dissolved with phenol to lower the dew point. Therefore, the method of uniformly spraying is preferable, and the method of spraying as uniformly as possible over the entire cross section of the pipe in a mist state is particularly preferable. Such a spraying means is not particularly limited, but the most practical method is to provide a nozzle above the inner wall of the pipe and blow it into a mist.

The spraying position is not particularly limited, but a position near the top of the column where the concentration or content of bisphenol A is considered to be the highest is preferable. Spray bisphenol A at as many positions as possible, including at least near the top of the tower.
Is preferably captured in a phenol-containing liquid. If the phenol spraying position is located too downstream of the process pipe, the area where the supplied phenol-containing liquid does not come into contact may be already blocked, which is not preferable. The gas containing bisphenol A captured in the phenol-containing liquid is liquefied in the condenser according to the gas flow from the distillation column.

As the phenol-containing liquid to be sprayed, the condensate recovered in the condenser can be most easily used, but the phenol-containing liquid used in the present invention is not limited to this condensate. However, it is preferable for the purpose of the present invention to contain no phenol or bisphenol A of phenol water. The temperature of the sprayed phenol-containing liquid must be adjusted so as not to lower the temperature of the phenol gas. For this purpose, it is necessary to consider not only the temperature of the phenol-containing liquid to be sprayed but also the latent heat of vaporization when the contained liquid vaporizes in the pipe. Usually, 50 to 80 ° C is preferable, although it depends on the amount to be sprayed. Too high temperature is not preferable because it causes insufficient cooling in the condenser. In order to keep this liquid temperature in a required state, it is also effective to wind a trace of 50 ° C. or higher on the pipe so that the temperature is equal to or higher than the freezing point (41 ° C.) of phenol. If the amount of the phenol-containing liquid sprayed is large, the amount of recovery in the condenser will increase, so it is preferable to make the amount appropriate. Usually, the amount of phenol sprayed is in the range of 0.1 to 3 times the amount of phenol withdrawn from the top of the distillation column.

An example will be described below.

【Example】

(Example 1) In Fig. 1, an adduct of bisphenol A and phenol was heated at 120 ° C, and the obtained molten adduct 2 was supplied to the distillation column 1 at 10,000 kg / hr.
The melt 3 is distilled under the conditions of 25 Torr and 170 ° C.,
Phenol gas 4 was distilled off from the top of the tower at about 3500 kg / hr. Further, bisphenol A6 was withdrawn from the bottom of the tower at a rate of about 6500 kg / hr. Distilled phenol gas from the top of the distillation column 1 in the process pipe 5
It is liquefied by the condenser 6 which is connected with a distance of 0 m, and is received from the condenser (not shown).
Was sent to. 1,000 parts of the phenol-containing liquid 7
50 ° C. from the process pipe inlet 5a (50 cm from the tower top) for discharging phenol vapor at the tower top at kg / hr
After spraying and distilling, it was possible to operate stably for a long time.

(Comparative Example 1) The same operation as in Example 1 was conducted except that the phenol-containing liquid was not sprayed into the process pipe. The operation pressure could not be maintained within 2 weeks after the operation and the apparatus was stopped. Came to. When observing the process pipe between the distillation column and the condenser and the inside of the spray nozzle, bisphenol A precipitate was found on the inner surface of the process pipe.

[0016]

EFFECTS OF THE INVENTION By taking the above-mentioned means, bisphenol A in the phenol gas to be distilled off is absorbed by the phenol-containing liquid, and bisphenol A is absorbed.
Of a high concentration liquid of bisphenol A due to the entrainment of droplets, etc.
Since it was possible to lower the temperature from 41 ° C to 41 ° C, it became possible to prevent clogging in the piping. By preventing the pipe from becoming clogged or becoming clogged, the rise in the pressure inside the pipe was eliminated, so that stable operation can be continued for a long period of time, and a bisphenol A product of good quality can be obtained. became.

[Brief description of drawings]

1 is a schematic diagram of the process used in Example 1 to carry out the method according to the present invention. FIG.

[Explanation of symbols]

1: Distillation tower 2: Molten adduct supplied to the distillation tower 3: Melt liquid distilled in the distillation tower 4: Phenol gas 5: Process pipe 5a: Nozzle for spraying a phenol-containing liquid on the process pipe 6: Bisphenol A 7 : Phenol-containing liquid 8: Condenser

─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Hideki Suda 2-17-15 Tsukushima, Chuo-ku, Tokyo Within Tsukishima Machinery Co., Ltd. (72) Masazumi Takahashi 2-17-15 Tsukishima, Chuo-ku, Tokyo Machinery Co., Ltd. (56) Reference JP-A-7-69951 (JP, A) JP-A-6-107578 (JP, A) JP-A-4-54143 (JP, A) JP-A-4-13640 ( JP, A) JP 63-275539 (JP, A) JP 63-159335 (JP, A) JP 61-151141 (JP, A) JP 59-62544 (JP, A) (58) ) Fields surveyed (Int.Cl. ⁷ , DB name) C07C 39/00 C07C 37/00

Claims (3)

(57) [Claims] 1. A method for producing bisphenol A by introducing an adduct of bisphenol A and phenol into a distillation column and distilling phenol vapor from the upper part of the distillation column through a process pipe to distill the phenol vapor. The method for producing bisphenol A is characterized in that the removal is carried out while spraying the phenol-containing liquid in the process pipe in the immediate vicinity of the distillation column . 2. A phenol is provided above the inner wall of the pipe to provide phenol.
The bisphenol according to claim 1, wherein the contained liquid is blown in a mist state.
Manufacturing method of A. 3. The temperature of the phenol-containing liquid to be sprayed is 50 to 50.
The method for producing bisphenol A according to claim 1, wherein the temperature is 80 ° C.
Law .