JP2001002612A - Production of phenols - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a method for producing phenols in which the progress of reboiler fouling in a distillation system can be suppressed by positively contacting oil with water in a decomposition product-storing tank to separate alkali metal salts in a contained state in an aqueous phase. SOLUTION: When decomposing hydroperoxides obtained by oxidizing at least one hydrocarbon with an oxygen-containing gas to produce phenols corresponding to the hydroperoxides, this method is to feed decomposition products obtained by decomposing the hydroperoxides and comprising alkali metal salts into a sparger placed in an aqueous phase on the bottom of a decomposition product-storing tank and to positively contact an oily phase with the aqueous phase to separate the alkali metal salts in a contained state in the aqueous phase.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a method for producing phenols, and more particularly to a decomposition product obtained by decomposing a corresponding hydroperoxide obtained by oxidizing a hydrocarbon with an oxygen-containing gas. The present invention relates to a method for producing phenols in which an alkyl metal salt is removed from a phenol and the progress of reboiler fouling in a distillation purification system is suppressed.

[0002]

2. Description of the Related Art Hydrocarbons are oxidized with an oxygen-containing gas,
The process of producing the corresponding hydroperoxides and then decomposing with acids to produce phenols is a technique known as the cumene process.

However, the acid used to decompose hydroperoxides is neutralized with an alkali metal salt to prevent equipment corrosion, and the alkali metal compound caused by this alkali metal salt causes reboiler fouling in a distillation system. Trigger.

[0004]

When the above-mentioned reboiler fouling occurs, an upper limit is set for the distillation temperature, which hinders stable operation. Therefore, the plant is temporarily stopped to clean the inside of the system (washing). Shut down), and some plants require washing shutdown several times a year, causing a large loss in phenol production.

The present invention has been made to solve the above-mentioned problems in the production of phenols, and the fouling cause is improved by enhancing the contact between the oil phase and the aqueous phase in the decomposition product storage tank. An object of the present invention is to provide a method for producing phenols, which removes an alkali metal salt as a substance from an aqueous phase, suppresses fouling in a distillation system, stabilizes the operation of phenols, and reduces loss due to washing shutdown. And

[0006]

The process for producing phenols according to the present invention is via a corresponding hydroperoxide obtained by oxidizing a hydrocarbon with an oxygen-containing gas, and comprises a reboiler existing in the system. The present inventors have found that entrainment of an alkali metal salt, which is a fouling substance, into a distillation system can be suppressed by actively contacting an oil phase and an aqueous phase in a decomposition product storage tank. It is a thing.

That is, the present invention relates to a method for producing a corresponding phenol by decomposing a hydroperoxide obtained by oxidizing a hydrocarbon with an oxygen-containing gas, wherein the alkali metal salt obtained by decomposing the hydroperoxide is provided. Is introduced into a sparger installed at the bottom of the aqueous phase of the decomposition product storage tank, and the oil phase is positively brought into contact with the aqueous phase to separate the alkali metal salt into the aqueous phase. This is a method for producing phenols in which progress of reboiler fouling to a distillation system is suppressed.

[0008]

BEST MODE FOR CARRYING OUT THE INVENTION The starting material hydrocarbon in the present invention is a paraffin having a secondary carbon, an olefin,
Specific examples of cycloparaffins, arylalkyl hydrocarbons and the like, as preferred examples of paraffins having a secondary carbon, such as isobutane, olefins such as pentene and isobutene, cycloparaffins such as cyclopentane and cyclohexane, and arylalkyl hydrocarbons. Examples thereof include cumene and cymen, but are not limited thereto.

The arylalkyl hydrocarbon includes a compound represented by the following general formula (I).

[0010]

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(Wherein, P and Q represent hydrogen or an alkyl group, which may be the same or different, x represents an integer of 1 to 3, and Ar represents an x-valent aromatic compound. A group hydrocarbon group).

In the general formula (I), at least one of P and Q is preferably an alkyl group,
In particular, it is preferable that all are alkyl groups. The alkyl group is particularly preferably a methyl group. Examples of the aromatic hydrocarbon group include x-valent hydrocarbon groups derived from benzene, naphthalene, biphenyl, diphenyl ether and the like, and preferably x-valent hydrocarbon groups derived from benzene or naphthalene.

Accordingly, in the present invention, preferred specific examples of the arylalkyl hydrocarbon include diisopropylbenzenes such as cumene, cymene, m-diisopropylbenzene and p-diisopropylbenzene;
Triisopropylbenzenes such as 1,3,5-triisopropylbenzene, ethylbenzene, sec-butylbenzene, sec-butylethylbenzene, isopropylnaphthalenes, diisopropylnaphthalenes such as 2,6-diisopropylnaphthalene, isopropylbiphenyls, 4,
Examples thereof include diisopropyl biphenyls such as 4′-diisopropyl biphenyl, and a mixture of two or more of these. Among them, citrate is preferably used.

In the present invention, specific examples of the alkali metal salt which is a reboiler fouling causing substance include decomposition neutralizers such as sodium hydroxide, potassium hydroxide, sodium carbonate, potassium carbonate and the like. In addition, sodium sulfate, sodium formate, sodium acetate, sodium oxalate, and the like, which are salts in which the acid in the system is neutralized, can be exemplified. Further, it includes, but is not limited to, an alkali metal which acts as a counter cation of the complex salt.

According to the present invention, an oil phase and an aqueous phase are positively brought into contact with each other in a decomposition product storage tank before a distillation system feed,
It was noted that the reduction of the content of the alkali metal salt, which is a reboiler fouling causing substance, from the distillation system feed suppressed the rise of the chest press indicating the degree of progress of the reboiler fouling.

Here, as a method for positively contacting the oil phase and the aqueous phase in the decomposition product storage tank, a decomposition product containing an alkali metal salt (hereinafter, simply referred to as a decomposition product) is used. By introducing the product into a sparger installed at the bottom of the aqueous phase of the product storage tank, the dispersing effect during the dipping of the aqueous phase can be enhanced, and the oil-water contact can be enhanced.

In this sparger, the smaller the pores are, the better the dispersion efficiency is, but if the pores are too small, a disadvantage occurs in that a pressure difference is generated in the feed of the decomposition product storage tank. For about 80 T / H, it is desirable to make the hole diameter about 40 mm × about 20 holes. Furthermore, by providing a plurality of spargers, the pore diameter can be made smaller, and the number can be increased, and the contact efficiency can be improved.However, if determined in consideration of productivity such as the flow rate of decomposition products, Well, it is not limited to these.

[0018] In addition, a stationary tank is provided between the decomposition neutralization tank and the decomposition product storage tank, and the decomposition products are fed from the lower part of the stationary tank and brought into contact with the aqueous phase to thereby achieve an oil-water contact efficiency. May be used. In this case, the number of stationary tanks is preferably as large as possible, but the number may be determined in terms of economy and efficiency.

In order to enhance the contact between oil and water in the above-mentioned decomposition product storage tank, the tank is vertically elongated so that the height of the tank is about two to three times the diameter of the tank, or the diameter of the lower part of the tank is narrowed down. Alternatively, there may be mentioned a method of strengthening oil-water contact with the same amount of water by introducing a decomposition product from the bottom. Here, the height of the oil-water interface depends on the shape of the tank, but should be as high as possible on the premise that the oil phase standing time is not hindered. The specific height of the water phase (height of the oil-water interface) is determined from the feed port for the decomposition product
It is desirable to design so that it is located at least about 1 to 3 m above.

In addition, not only water separated from the decomposition products brought in from the decomposition neutralization tank by liquid-liquid equilibrium, but also the amount of water added to the decomposition product storage tank is increased to actively enhance oil-water separation, and Efficiency of oil-water contact may be achieved by increasing the time for the decomposition products to dive in the aqueous phase.

Specifically, water may be directly added to the decomposition product storage tank, or a stream of a distillation system containing water together with valuables such as phenols may be recycled and fed. At that time, it is preferable to feed the hydrophobic oil phase at the same time because the oil-water separation tends to be hindered. Specifically, in the case of producing 200,000 T / Y cumene method phenol, it is desirable to feed 0.5 T / H of water and 2.0 T / H of α-methylstyrene as a by-product, but it is not limited thereto. Not something.

According to these methods, the position of the nozzle for extracting the oil phase from the decomposition product storage tank to the distillation system is set as high as possible to eliminate the entrainment of water in the distillation system, and the water phase is continuously or Periodic removal outside the tank can reduce the accumulation of alkali metal salts. The aqueous phase removed from these decomposition product storage tanks may be discarded, reused for the neutralization system, or returned to the valuable resource recovery system, taking into account productivity and economy. May be performed appropriately.

[0023]

The following describes the suppression of the progress of reboiler fouling by reducing the entrainment of alkali metal salts, which are reboiler fouling causing substances, into the distillation system.
The present invention will be described with reference to examples, but the present invention is not limited thereto.

Example 1 In a 200,000 T / Y scale cumene phenol production plant, a decomposition product feed port provided at the center of the bottom of a decomposition product storage tank having a tank height 2.5 times the tank diameter was installed. , And a sparger having 20 holes of 35 mmφ are provided. The height of the aqueous phase in this decomposition product storage tank is 1 m
The decomposition product was introduced at a flow rate of 65 T / H from the decomposition product feed port provided with a sparger while dipping the aqueous phase. The aqueous phase was continuously drawn out of the tank while maintaining the height of the oil-water interface.

After the oil / water was sufficiently separated in the decomposition product storage tank, the concentration of Na accompanying the oil phase fed to the distillation system was 0.5 ppm. The reboiler fouling frequency of the distillation system was 2 times / year.

Comparative Example 1 The same treatment as in Example 1 was performed except that the decomposition product was fed to a decomposition product storage tank without passing through a sparger. After the oil-water separation in the decomposition product storage tank, the Na concentration accompanying the oil phase fed to the distillation system was analyzed and found to be 1.3 ppm, whereby the reboiler fouling frequency of the distillation system was 3 times / year. Met.

[0027]

The decomposition product is positively brought into contact with oil-water in the decomposition product storage tank, and the alkali metal salt is separated into the aqueous phase, thereby reducing the entrainment of the reboiler fouling causing substance into the distillation system. Since the progress of reboiler fouling can be suppressed, a method for producing phenols which is excellent in productivity and economical can be provided, which is industrially superior.

 ────────────────────────────────────────────────── ─── Continued on front page (72) Inventor Hideki Matsuo 1-6-6 Takasago, Takaishi-shi, Osaka Mitsui Chemicals, Inc. F-term (reference) 4H006 AA02 AC42 AC44 AD16 BD20 BD80 BN30 FE13

Claims (4)

[Claims] 1. A method for producing a corresponding phenol by decomposing a hydroperoxide obtained by oxidizing a hydrocarbon with an oxygen-containing gas to produce a corresponding phenol, comprising decomposing a hydroperoxide containing an alkali metal salt obtained by decomposing the hydroperoxide. The product is introduced into a sparger installed at the bottom of the aqueous phase of the decomposition product storage tank, and the alkali metal salt is positively brought into contact with the aqueous phase to separate the alkali metal salt into the aqueous phase. A method for producing phenols in which the progress of reboiler fouling to a distillation system is suppressed. 2. The method according to claim 1, wherein the hydrocarbon is represented by the following general formula (I). (Wherein P and Q represent hydrogen or an alkyl group and may be the same or different from each other, and X is 1 to
An integer of 3, and Ar represents an X-valent aromatic hydrocarbon group. 2. The method according to claim 1, wherein the arylalkyl hydrocarbon represented by the formula (1) is oxidized with an oxygen-containing gas to selectively convert to the corresponding arylalkyl hydroperoxides. 3. An arylalkyl hydrocarbon represented by the general formula (I) is: cumene, cymene, m-diisopropylbenzene, p-diisopropylbenzene, 1,3,5-triisopropylbenzene, isopropylnaphthalene, diisopropylnaphthalene, 3. The method according to claim 2, wherein the method is isopropyl biphenyl, diisopropyl biphenyl, or a mixture of two or more thereof. 4. The method according to claim 2, wherein the arylalkyl hydrocarbon is cumene.