JP2023073796A - Method for producing phenols - Google Patents

Abstract

To provide a method for producing phenols that enables sufficient separation between oil and water in an oil-water separation step in the phenol production method.SOLUTION: A method for producing phenols includes: a neutralization step for neutralizing an acid-decomposed cumene hydroperoxide reaction solution with an alkali; an oil-water separation step for separating the neutralized reaction solution into an oil phase liquid and an aqueous phase liquid; and a washing step for mixing the oil phase liquid with washing water to wash it. In the washing step, the mixture of the oil phase liquid and the washing water contains a metal element, excluding alkali metals of Group 1 in the periodic table, of 0.1 mass ppm or more and 25 mass ppm or less.SELECTED DRAWING: Figure 1

Description

The present invention relates to a method for producing phenol.

Phenol is generally produced industrially by the cumene process. Production of phenol by the cumene method involves oxidizing cumene to produce cumene hydroperoxide (hereinafter referred to as CHP).
), an acid decomposition step in which CHP is acid-decomposed to produce phenol and acetone, a neutralization cleaning step in which the decomposition product is neutralized and washed to remove salts, and in the cleaning solution It has a recovery step of separating components other than phenol from the product and recovering phenol.

In the acid decomposition step in the method for producing phenol by the cumene method, an acid such as sulfuric acid is added to efficiently decompose CHP. If acid remains in this acid decomposition product, it becomes a catalyst for generating heavy materials by heating in the subsequent recovery step. Therefore, in the neutralization washing step before the recovery step, washing water to which an alkali such as sodium carbonate is added is brought into contact with the acid decomposition product to extract and remove the acid into the washing water. In addition, in the neutralization and washing step, organic acids generated as impurities in the oxidation step for producing CHP are also extracted and removed at the same time.

Washing water that has been brought into contact with the acid decomposition product contains the extracted acid and salts, and if this is brought into the recovery process, it precipitates as a sodium salt in the distillation column and clogs the column (Patent Document 1). . Column clogging destabilizes the operation of the distillation column, eventually requiring the plant to be shut down for cleaning, which hinders continuous plant operation. Therefore, it is necessary to separate the wash water after extraction from the acid decomposition products.

In addition, metal components are eluted from metal pipes and equipment in plants due to corrosion. Occlude the kind. For this reason, plants take measures such as changing the materials of metal pipes and equipment to corrosion-resistant materials to suppress the elution of metal components.

Separation of the acid-decomposed product and washing water is oil-water separation, and methods for this oil-water separation include stationary separation, flocculation separation using a filter, centrifugation, and the like.

The oil-water separation speed is affected by physical properties such as oil-water density difference, interfacial tension, and dispersed droplet size, which are caused by differences in liquid composition, the presence or absence of surface-active substances, and mixing speed. It has not been sufficiently clarified how various impurities and metals produced and mixed in the process affect the oil-water separation.

JP-A-7-24211

An object of the present invention is to provide a method for producing phenol, which enables good oil-water separation in the oil-water separation step of the phenol production method.

The present inventors found that in the washing process of mixing washing water with the oil phase liquid after oil-water separation in the production of phenol, the particle size of water particles dispersed in the mixed liquid of the oil phase liquid and washing water Since the oil-water separation property deteriorates when the is small, the oil-water separation property is improved by intentionally allowing a metal element other than an alkali metal belonging to Group 1 of the periodic table to be present in the mixed liquid at a predetermined concentration. I have found that it is possible to

That is, the gist of the present invention is a neutralization step of neutralizing an acid decomposition reaction solution of cumene hydroperoxide with an alkali, an oil-water separation step of separating the neutralized reaction solution into an oil phase liquid and an aqueous phase liquid, and washing step of washing by mixing washing water with the phase liquid, wherein the mixed liquid of the oil phase liquid and washing water in the washing step is a metal other than alkali metals belonging to group 1 of the periodic table. The present invention relates to a method for producing phenol containing an element within the range of 0.1 mass ppm or more and 25 mass ppm or less.

ADVANTAGE OF THE INVENTION According to this invention, in the manufacture of phenol, it is possible to provide a method for producing phenol, which enables good oil-water separation in the oil-water separation step. As a result, it is possible to prevent the salts, organic acids, and the like contained in the neutralized and washed water from being brought into the oil-water separation device and the downstream refining device such as the distillation column, and clogging the pipes. And it becomes possible to continuously and stably operate the downstream refining equipment for a long period of time.

It is a schematic block diagram of an oil-water separation experimental apparatus.

Although the present invention will be described in detail below, the present invention is not limited to the following description, and can be arbitrarily modified without departing from the gist of the present invention.

In addition, unless otherwise specified, the numerical range represented by using "~" in this specification is "~
” means a range including the numerical values described before and after as lower and upper limits, and “A to B” are
It means A or more and B or less.
As used herein, “mass ppm” is “ppm” calculated with the unit as mass, and means 1 mass ppm=1×10 ⁻⁴ mass %.

[Method for producing phenol]
The present invention relates to a method for producing phenol based on the cumene method.
The method for producing phenol of the present invention is a method for producing phenol having a neutralization step, an oil-water separation step, and a washing step, which will be described later.

In the method for producing phenol of the present invention, the neutralization step, the oil-water separation step, and the washing step can be repeated in this order any number of times.
Furthermore, the method for producing phenol of the present invention can have a recovery step, which will be described later, after the washing step.

Furthermore, the method for producing phenol of the present invention can include a step of oxidizing cumene, which will be described later, and a step of acid-decomposing CHP, which will be described later, before the neutralization step.
Furthermore, the method for producing phenol of the present invention can include a step of concentrating CHP, which will be described later, between the oxidation step and the acid decomposition step.

As a general embodiment of the method for producing phenol, a known method such as the conditions described in JP-A-2017-178826 can be used.

Each step described above will be described in order below.

[Cumene oxidation process]
The method for producing phenol of the present invention can include a step of oxidizing cumene to produce CHP before the neutralization step described below.
The cumene used for the oxidation of cumene is preferably refined to 99.5% by weight or more by reaction of benzene and propylene and distillation. This can be mixed with cumene recovered from the CHP concentration step described later, or cumene obtained by hydrogenating α-methylstyrene separated from a mixture of phenol, acetone, etc. after phenol synthesis in a distillation column. I don't mind.

The oxidation reaction of cumene is carried out at 40° C. to 130° C. under normal pressure or under pressure by blowing in a mixed gas containing oxygen and an inert gas. Examples of the mixed gas include air, air with increased or decreased oxygen concentration, and the like, among which air with increased oxygen concentration is preferred. The oxidation reactor may be one in which the reaction is carried out in one stage, or one in which the reaction is carried out in multiple stages of two or more stages. In the latter case, a mixed gas containing oxygen and an inert gas is usually additionally supplied for each step. When α-methylstyrene is one of the target products, conditions suitable for the plant may be selected so that the desired amount of dimethylbenzyl alcohol is generated during the oxidation reaction.
A cumene solution containing 10 to 40% by weight of CHP is obtained by the oxidation reaction of cumene described above.

[Concentration step of CHP]
In the method for producing phenol of the present invention, after the cumene oxidation step described above and before the neutralization step described later, or before the neutralization step described later, before the acid decomposition step of CHP described later, A step of concentrating CHP can be included in which the cumene solution containing CHP obtained in the oxidation step is concentrated.
The cumene solution obtained in the cumene oxidation step described above is concentrated to a CHP concentration of preferably 65% by weight or more, more preferably 80% by weight or more, and more preferably 80% by weight or more and 90% by weight or less. Since CHP undergoes a violent cleavage reaction at high temperatures or in the presence of a catalyst, the content is preferably 90% by weight or less from the standpoint of safety.
A method for concentrating the cumene solution is not particularly limited, but concentrating under reduced pressure is preferable. By concentrating under reduced pressure, it is also possible to degas the air blown in during the oxidation reaction. The concentrated CHP solution is diluted with acetone and subjected to the next acidolysis step.

[Acid decomposition step of CHP]
In the method for producing phenol of the present invention, after the cumene oxidation step or the CHP concentration step described above and before the neutralization step described later, a cumene solution containing CHP obtained in the oxidation step or the concentration step is added. , in the presence of an acid catalyst to produce a solution containing phenol and acetone.
Specifically, in the cumene solution containing CHP obtained in the concentration step, in the presence of an acid catalyst, a cleavage reaction of CHP is caused, and phenol, acetone, and α-methylstyrene resulting from the above-mentioned dimethylbenzyl alcohol and A mixture containing other by-products is obtained.
Examples of the acid catalyst include sulfuric acid.

The acid decomposition reaction of CHP is usually carried out at a reaction temperature of 60°C to 90°C. The acid decomposition reaction of CHP is an exothermic reaction, and heat is removed.
Almost all of CHP is cleaved to phenol and acetone, and as by-products, it consists of a mixture containing phenol dimers, heavy oils such as cumylphenol (HE (heavy end)), and organic acids. An acid decomposition product is obtained.
That is, the acid decomposition reaction solution obtained by decomposing CHP with an acid catalyst is a solution containing phenol and acetone. Contains acid decomposition products including acids and the like.

[Neutralization step]
The method for producing phenol of the present invention includes a neutralization step of neutralizing the acid decomposition reaction solution of CHP with an alkali.
As one embodiment of the neutralization step in the present invention, the acid decomposition reaction solution obtained by decomposing CHP in the presence of an acid catalyst in the aforementioned CHP acid decomposition step is neutralized with an alkali and washed (hereinafter referred to as simply "neutralizing with alkali"). Examples of the neutralization washing water used for neutralization with alkali include an alkaline aqueous solution.
In the neutralization step, a solution containing phenol and acetone is brought into contact with neutralization washing water such as an alkaline aqueous solution multiple times. As a result, after neutralizing the acid catalyst such as sulfuric acid used in the acid decomposition of CHP to obtain a neutralized salt, etc. are transferred to the neutralized washing water and extracted. The contact of the solution containing phenol and acetone with the neutralization wash water is preferably carried out in countercurrent and in multiple stages. Further, these treatments in the neutralization step can be performed using a known mixing device such as a line mixer.

As a neutralizing agent used for neutralization with an alkaline aqueous solution, an aqueous solution of ammonia, an aqueous solution of a basic compound containing an alkali metal or an alkaline earth metal, an anion exchange resin, or the like can be used. Among these, aqueous solutions of sodium-containing basic compounds such as sodium phenolate, sodium hydroxide and sodium carbonate are preferably used. The sodium-containing basic compound in this aqueous solution is preferably added in such an amount that the pH of the aqueous phase after neutralization is about 6.

[Oil-water separation process]
The method for producing phenol of the present invention includes an oil-water separation step of separating the reaction liquid neutralized in the neutralization step into an oil phase liquid and an aqueous phase liquid.
The mixture of the acid decomposition product after neutralization and washing and the neutralization and washing water obtained in the neutralization step is separated into an aqueous phase and an oil phase liquid (organic phase) by an oil-water separator, and the aqueous phase is An oil phase liquid is obtained by removing. When neutralized with an alkali metal-containing basic compound, part of the phenol becomes a salt with an alkali metal (sodium phenate, etc.) and migrates to the aqueous phase, resulting in a decrease in phenol yield. Therefore, it is preferable to add a salt such as sodium sulfate to the aqueous phase to prevent phenol in the oil phase liquid from migrating to the aqueous phase.
Moreover, these treatments in the oil-water separation process can be performed using a known oil-water separation apparatus such as a stationary separation tank.

[Washing process]
The washing step in the present invention includes washing by mixing the oil phase liquid obtained in the oil-water separation step with washing water.
The acid decomposition step of CHP is preferably carried out using sulfuric acid as described above, and the sulfuric acid used is converted into Glauber's salt (decahydrate of sodium sulfate) in the neutralization step. Since the oil phase liquid separated in the oil-water separation step contains neutralized salts such as mirabilite, the oil phase liquid is further washed in order to remove it.

The washing of the oil phase liquid may be performed using a mixing device such as a line mixer and an oil-water separation device such as a static separation tank in the same manner as the device used for neutralization, or an extraction separation device such as a coalescer. You can use it. The aqueous phase after washing the oil phase liquid may be used as the washing water in the above neutralization washing step. As a result, the phenol that has migrated to the aqueous phase can be recovered.

Washing water used for washing the oil phase liquid is not particularly limited, but ion-exchanged water or distilled water can be used. The washing process of the oil phase liquid is performed for the purpose of removing salts in the oil phase liquid. It is necessary to reduce the salt content of

In the method for producing phenol of the present invention, it is contained in the mixture of the oil phase liquid sent from the outlet of the neutralization step and the washing water used for washing the oil phase liquid at the inlet of the oil phase liquid washing step. , the lower limit of the content of metal elements excluding alkali metals belonging to Group 1 of the periodic table (hereinafter simply referred to as "alkali metals belonging to Group 1"). From the viewpoint of good oil-water separation afterward, it is 0.1 mass ppm or more, preferably 0.2 mass ppm or more, more preferably 0.5 mass ppm or more, relative to the total mass of the mixed liquid. be. On the other hand, in the mixed solution, the upper limit of the content of the metal elements excluding Group 1 alkali metals is set to It is 25 ppm by mass or less, more preferably 3 ppm by mass or less, and more preferably 2 ppm by mass or less, relative to the mass.

The above upper and lower limits can be combined arbitrarily. For example, in the mixed solution, the content of metal elements other than alkali metals belonging to Group 1 is 0.1 mass ppm or more and 25 mass ppm or less with respect to the total mass of the mixed solution, preferably It is 0.2 mass ppm or more and 3 mass ppm or less, more preferably 0.5 mass ppm or more and 2 mass ppm or less.

The reason for excluding the content of alkali metals belonging to Group 1 from the content of metal elements is that the presence of alkali metals belonging to Group 1, such as sodium, deteriorates the oil-water separation property. This is because the content of metal elements, excluding Group 1 alkali metals, is important for improving the oil-water separation property.

As a method for controlling the content of metal elements other than alkali metals belonging to Group 1, washing water containing metal elements other than alkali metals belonging to Group 1 is prepared in advance, and in the washing step, The washing water is mixed with the oil phase liquid so that the content of the metal element in the mixture of the oil phase liquid and the washing water is in the range of 0.1 ppm by mass or more and 25 ppm by mass or less. method.

Alternatively, as a method for controlling the content of metal elements other than alkali metals belonging to Group 1, there are known methods such as adding eluted metals by placing a sacrificial metal material in an intermediate tank or the like provided between steps. mentioned.

Alkali metals belonging to Group 1 include, but are not particularly limited to, lithium, sodium, potassium, rubidium, and the like. Among them, sodium and potassium are preferred.

Metal elements other than alkali metals belonging to Group 1 are not particularly limited, but include typical metals belonging to Periods 4 and 5 in the periodic table. From the viewpoint of ease of handling, iron, copper and zinc can be mentioned. Among them, iron is preferable.

If an alkali metal belonging to Group 1 such as sodium and an organic acid coexist in the oil phase liquid washing step, the oil-water separation property after washing the oil phase liquid deteriorates. At least one of an alkali metal belonging to Group 1 such as sodium and an organic acid in the mixture of the oil phase liquid sent from the outlet of the neutralization step and the washing water used for washing the oil phase liquid at the inlet It is preferable to set the concentration to a predetermined value or less.

The concentration of the group 1 alkali metal such as sodium in the mixed solution is preferably 250 mass ppm or less, more preferably 100 mass ppm or less, relative to the total mass of the mixed solution.

As a method for reducing the concentration of group 1 alkali metals such as sodium, pH is lowered by adding an acid (preferably sulfuric acid) to the washing water in the neutralization washing process, and washing efficiency is increased by multistage oil-water separation equipment. etc.

The concentration of the organic acid in the mixed liquid is preferably 520 mass ppm or less, more preferably 100 mass ppm or less, relative to the total mass of the mixed liquid. The organic acid used herein includes acids such as formic acid, acetic acid, and oxalic acid, which are by-produced in the cumene oxidation reaction.
From the viewpoint of reducing the concentration of sodium sulfate contained in the washing water, the concentration of sulfuric acid in the mixed liquid is preferably 50 mass ppm or less, more preferably 20 mass ppm or less, relative to the total mass of the mixed liquid.

Examples of methods for reducing the organic acid concentration include increasing the pH by adding alkalis to the washing water in the neutralization step, and increasing the washing efficiency by adding multiple stages to the washing oil-water separation equipment. As the alkalis to be added, the same alkalis as those used for the alkaline washing water in the neutralization step can be used.

[Recovery process]
After the above-described washing step, the method for producing phenol of the present invention can have a recovery step of recovering phenol by distilling the oil phase liquid after washing.
In the recovery step, a mixture containing phenol, acetone, α-methylstyrene and heavy ends (HE) on the liquid side of the oil phase is separated into respective components by distillation.

For distillation, known methods such as conditions described in JP-A-2015-178476 and JP-A-2015-182986 can be used.

The number of distillations and which components to extract in each distillation can be set arbitrarily, but usually the first distillation targets light components, especially acetone, and distills water and unreacted cumene. phenol and α-methylstyrene are distilled off by the second distillation, and the residue is used as heavy ends (HE), and the distilled fraction is subjected to a third distillation to separate phenol and α-methylstyrene. Alternatively, the first distillation targets acetone and α-methylstyrene to remove water and unreacted cumene, and the second distillation separates phenol and HE. And, of course, the acetone and α-methylstyrene obtained in the first distillation may be separated separately. In any case, more distillations than the number of target substances are required, and in order to further improve the purity, the number of distillations is sometimes increased. Extractive distillation may also be carried out in which distillation is carried out while adding an appropriate solvent as necessary.

After distillation, the product is phenol that has reached the desired purity.

EXAMPLES The present invention will be described in more detail with reference to examples below, but the present invention is not limited to these examples. In this example, an experiment simulating the oil-water separation process of the phenol production method was conducted to estimate the effect of the method of the present invention.

Acetone, cumene, α-methylstyrene, phenol, formic acid, and sodium hydroxide used in Examples and Comparative Examples were special grade reagents manufactured by Fuji Film Wako Pure Chemical Industries, Ltd.
In addition, Polytetsu (product name, manufactured by Nittetsu Mining Co., Ltd., main component: polyferric sulfate aqueous solution) (hereinafter referred to as "Polytetsu reagent") was used as a metal element other than alkali metals belonging to Group 1. .

[Oil-water separation experiment]
The oil-water separation experimental apparatus shown in FIG. 1 was used for the examples and comparative examples. This experimental apparatus for oil-water separation comprises a raw material tank 2 having an internal volume of 1.8 L equipped with a stirrer 1, a liquid feed pump 4, and a coalescer tank 6 having an internal volume of 0.7 L. The coalescer tank 6 has a carbon fiber filter element 5 with a capacity of 100 mL and a filtration accuracy of 15 μm.

An oil-water separation experiment was performed according to the following procedure.
After 1 kg of the raw material liquid was put into the raw material tank 2, the liquid was mixed and stirred by the stirrer 1 so that the liquid became uniform, and the liquid temperature was adjusted to 40°C by the heater 3. After that, the liquid is sent by the liquid sending pump 4 at a flow rate of 150 mL / min, the liquid is passed through the filter element 5 to separate the oil and water, the separated aqueous phase is settled in the coalescer tank 6, and the separated oil phase liquid was obtained from the exit nozzle 7.

The water concentration in the separated oil phase was determined by the Karl Fischer reagent volumetric titration method using a moisture meter (product name: CA-200 type, manufactured by Nitto Seiko Analytic Tech Co., Ltd.). As Karl Fischer moisture measurement reagents, 3 mg of Aquamicron ^TM titrant SS-Z (manufactured by Mitsubishi Chemical Corporation) and Aquamicron (registered trademark) dehydrated solvent KTX (for ketones, non-pyridine/chloroform) (manufactured by Mitsubishi Chemical Corporation) were used. .

[Example 1]
Ion-exchanged water, acetone, cumene, α-methylstyrene, phenol, formic acid, sulfuric acid, sodium hydroxide, and Polytetsu reagent were mixed to obtain a mixed solution shown in Table 1.
The amount of the Polytetsu reagent was blended so that the content of elemental iron in the finally obtained mixed solution was 1.0 ppm by mass.
The obtained mixture was subjected to oil-water separation using the oil-water separation experimental apparatus shown in FIG. 1, and the water concentration in the obtained oil phase liquid (hereinafter referred to as "oil phase water concentration") was measured. Table 1 shows the results.

[Examples 2 to 4]
The polytetsu reagent was blended so that the content of the iron element in the mixed solution was 0.5 mass ppm, 0.2 mass ppm, and 0.1 mass ppm, respectively, and the mixed solution shown in Table 1 was obtained. . An experiment was conducted in the same procedure as in Example 1, and the water concentration in the oil phase was measured. Table 1 shows the results.

[Comparative Example 1]
A mixed solution shown in Table 1 was obtained without using the Polytetsu reagent. An experiment was conducted in the same procedure as in Example 1, and the oil phase water concentration was measured. Table 1 shows the results.

[Discussion]
In Examples 1 to 4, the oil phase water concentration after the oil-water separation experiment was low.
On the other hand, in Comparative Example 1, since the mixed liquid did not contain metal elements other than Group 1 alkali metals, the oil phase water concentration was high after the oil-water separation experiment.

From the above results, in the production of phenol having the neutralization step, the oil-water separation step, and the step of washing the oil phase liquid as defined in claim 1, It is expected that oil-water separation property can be improved by intentionally including metal elements other than alkali metals belonging to Group 1.
Phenol, for example, is consumed in large quantities as a raw material for epoxy resins, polycarbonate resins, phenolic resins, and polyester resins, and is therefore produced in large quantities on an industrial scale of, for example, 100,000 tons/year or more. Therefore, in the production of phenol, if the oil-water separation property is improved even a little, for example, if the water concentration in the oil phase brought into the distillation column is reduced by even 1%, the energy required for heating in the distillation column can be reduced. It is industrially important from the viewpoint of reducing production costs by suppressing precipitation of salts dissolved in phase free water.

1 raw material agitator 2 raw material tank 3 raw material tank heater 4 liquid feed pump 5 filter element 6 coalescer tank 7 oil phase side outlet nozzle 8 aqueous phase side outlet nozzle

Claims (5)

a neutralization step of neutralizing an acid decomposition reaction solution of cumene hydroperoxide with an alkali;
an oil-water separation step of separating the neutralized reaction liquid into an oil phase liquid and an aqueous phase liquid;
a washing step of washing by mixing washing water with the oil phase liquid;
In the method for producing phenol having
Production of phenol, wherein the mixed liquid of the oil phase liquid and the washing water in the washing step contains metal elements excluding alkali metals belonging to Group 1 of the periodic table within the range of 0.1 mass ppm or more and 25 mass ppm or less. Method. In the washing step, washing water containing metal elements excluding alkali metals belonging to Group 1 of the periodic table is added to the oil phase liquid, and the content of the metal elements in the mixed liquid of the oil phase liquid and the washing water is 2. The method for producing phenol according to claim 1, wherein the mixture is in the range of 0.1 mass ppm or more and 25 mass ppm or less. 3. The method for producing phenol according to claim 1, wherein said metal element is iron. The method for producing phenol according to any one of claims 1 to 3, comprising an oxidation step of oxidizing cumene to produce cumene hydroperoxide before the neutralization step. The method for producing phenol according to any one of claims 1 to 4, further comprising, after the washing step, a recovery step of recovering phenol by distilling the oil phase liquid after washing.

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