JP2002275122A - Method for producing aromatic carboxylic acid - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a method for stably producing an aromatic carboxylic acid through preventing crude aromatic carboxylic acid crystals from sedimentation or deposition. SOLUTION: This method for producing an aromatic carboxylic acid comprises subjecting an alkylaromatic compound to liquid phase oxidation with an oxygen-containing gas blown from a relevant blowing section 12 in an oxidation reactor 1 in an aliphatic carboxylic acid-containing reaction solvent in the presence of an oxidation catalyst to form aromatic carboxylic acid crystals; wherein the oxidation reactor 1 is characterized by having the following construction: the lower part of the reactor is disposed with an agitator 3 having an agitating blade 3b above the upper surface of a rotary disc 3a disposed substantially horizontally and having no agitating blade under the lower surface of the rotary disc 3a.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a method for producing an aromatic carboxylic acid by subjecting an alkyl aromatic compound containing an alkyl substituent or a partially oxidized alkyl substituent to liquid phase oxidation with an oxygen-containing gas.

[0002]

2. Description of the Related Art Aromatic carboxylic acids are important as basic chemicals, and aromatic dicarboxylic acids are particularly useful as raw materials for fibers, resins and the like. For example, the demand for terephthalic acid as a polyester raw material has been increasing in recent years.

[0003] As a method for producing an aromatic carboxylic acid, generally, in an oxidation reactor, a heavy metal compound and a bromine compound are used as catalysts, and an alkyl-substituted aromatic compound is converted into a molecule in a reaction solvent containing a lower aliphatic carboxylic acid such as acetic acid. A method of contacting with a gaseous oxygen-containing gas to perform liquid phase oxidation is employed. In such a production method, an alkyl-substituted aromatic compound such as para-xylene as a raw material, a mixture of acetic acid and a catalyst as a raw material, and an oxygen-containing gas such as air are introduced into the reactor, and an oxidation reaction is performed by stirring with a stirrer. And aromatic carboxylic acids such as terephthalic acid.

FIG. 3 is a vertical sectional view showing a part of an oxidation reactor in the method for producing an aromatic carboxylic acid disclosed in JP-A-2000-44510. In FIG. 3, reference numeral 1 denotes an oxidation reactor which is formed in a vertical cylindrical shape and has
, And a stirrer 3 is arranged in the lower center. The stirrer 3 has radially arranged stirring blades 3b around a horizontally arranged disk 3a, and the rotating shaft 4 penetrates the lower wall 9 of the oxidation reactor 1 so that the driving device 5 Connected to In the production of the aromatic carboxylic acid using the above-mentioned oxidation reactor, first, an alkyl aromatic compound, a catalyst and a solvent are introduced into the oxidation reactor 1 through the raw material supply path 6 and the oxygen-containing gas is introduced into the oxidation reactor 1 through the gas introduction path 7, and the driving is performed. The stirring is performed by rotating the stirrer 3 by the device 5 to perform a liquid phase oxidation reaction. The crude aromatic carboxylic acid slurry produced by the reaction is passed through a slurry discharge passage 8
Is taken out by

In the oxidation reactor 1 used in the above-described manufacturing method, the stirrer 3 having the stirring blades 3b on the upper and lower surfaces of the disk 3a is used. However, there is a problem that the operation is hindered by the attachment of crystals of the aromatic carboxylic acid. As a result of investigating the cause, since the stirring blade 3b is also present under the disk 3a, the rotation of the stirring blade 3b causes the disk 3a to rotate.
Besides the swirling flows a and b formed above the disk 3a
It was speculated that a strong swirling flow c was generated below the disk, and the introduced oxygen-containing gas was involved, and the oxygen concentration locally increased on the lower side of the disk.

As the oxygen concentration increases, crystals tend to precipitate, so that the crude aromatic carboxylic acid crystals adhere from the lower part of the disk to the rotating shaft 4 and the baffle plate 2 while the oxidation reaction is continued. As a result, stirring is not sufficiently performed, and stable operation is impeded. On the other hand, it is possible to weaken the swirling flow by slowing the stirring speed, but it is difficult to bring the raw material, the solvent, the catalyst and the oxygen into sufficient contact for uniform mixing.

[0007]

SUMMARY OF THE INVENTION An object of the present invention is to provide a method for producing an aromatic carboxylic acid which can stably produce an aromatic carboxylic acid by preventing sedimentation and adhesion of a crude aromatic carboxylic acid crystal. It is to provide.

[0008]

The present invention is the following method for producing an aromatic carboxylic acid. (1) In a method for producing an aromatic carboxylic acid crystal by subjecting an alkyl aromatic compound to liquid phase oxidation with an oxygen-containing gas in a reaction solvent containing an aliphatic carboxylic acid in an oxidation reactor in the presence of an oxidation catalyst, A stirrer that has stirring blades on the upper surface of a rotating disk that is arranged horizontally and that does not have a stirring blade on the lower surface performs a reaction using an oxidation reactor arranged at the bottom of the tank. A method for producing an aromatic carboxylic acid. (2) The method according to the above (1), wherein the oxidation reactor has a plurality of oxygen-containing gas injection sections below the stirrer. (3) The method according to the above (1) or (2), wherein the stirring blade is provided so as not to protrude from the outer periphery of the disk. (4) The method according to (2) or (3), wherein the disk of the stirrer is located inside the oxygen-containing gas blowing section. (5) The method according to any one of (1) to (4) above, wherein the oxidation reactor has a baffle plate on an inner wall of a portion corresponding to the stirrer.

In the method of the present invention, the alkylaromatic compound as an oxidation raw material for producing an aromatic carboxylic acid includes an aromatic compound having an alkyl substituent or a partially oxidized alkyl substituent (hereinafter, simply referred to as an oxidation raw material). May be used). Such an aromatic compound may be monocyclic or polycyclic. Examples of the alkyl substituent include an alkyl group having 1 to 4 carbon atoms such as a methyl group, an ethyl group, an n-propyl group, and an isopropyl group. Examples of the partially oxidized alkyl group include an aldehyde group, an acyl group, a carboxyl group, and a hydroxyalkyl group.

Specific examples of aromatic compounds having an alkyl substituent, that is, alkyl-substituted aromatic hydrocarbons include, for example, m-diisopropylbenzene, p-diisopropylbenzene, m-cymene, p-cymene, m-xylene, An alkyl group having 1 to 4 carbon atoms such as p-xylene, trimethylbenzenes and tetramethylbenzenes is
Di or polyalkyl benzenes having from 2 to 4 di or polyalkyl naphthalenes having from 2 to 4 alkyl groups having 1 to 4 carbon atoms, such as dimethyl naphthalenes, diethyl naphthalenes and diisopropyl naphthalenes;
And polyalkylbiphenyls having 2 to 4 alkyl groups having 1 to 4 carbon atoms, such as dimethylbiphenyls.

The aromatic compound having a partially oxidized alkyl substituent is a compound in which the alkyl group in the above compound is partially oxidized and oxidized to the aldehyde group, acyl group, carboxyl group or hydroxyalkyl group. It is. Specific examples include, for example, 3-methylbenzaldehyde, 4-methylbenzaldehyde, m-
Toluic acid, p-toluic acid, 3-formylbenzoic acid,
Examples include 4-formylbenzoic acid and 2-methyl-6-formylnaphthalenes. These are used alone or as a mixture of two or more.

In the method of the present invention, a heavy metal compound and a bromine compound are used as an oxidation catalyst. Examples of such compounds are as follows. That is, as the heavy metal in the heavy metal compound, for example, cobalt, manganese, nickel, chromium, zirconium,
Copper, lead, hafnium, cerium and the like can be mentioned. These can be used alone or in combination, but it is particularly preferable to use a combination of cobalt and manganese. Such heavy metal compounds include, for example, acetate, nitrate, acetylacetonate, naphthenate, stearate, bromide, etc., with acetate being particularly preferred.

As the bromine compound, for example, molecular bromine,
Inorganic bromine compounds such as hydrogen bromide, sodium bromide, potassium bromide, cobalt bromide and manganese bromide; methyl bromide, methylene bromide, bromoform, benzyl bromide, bromomethyltoluene, dibromoethane, tribromoethane and Organic bromine compounds such as tetrabromoethane can be mentioned. These bromine compounds are also used alone or as a mixture of two or more.

In the present invention, the catalyst comprising the combination of the heavy metal compound and the bromine compound is used in an amount of 0.05 to 10 mol, preferably 0.1 mol, of bromine atom per 1 mol of heavy metal atom.
Those having a range of 2 to 2 mol are desirable. Such a catalyst is usually used as a heavy metal concentration in a reaction solvent of 10 to 100.
It is used in the range of 00 ppm, preferably 100 to 5000 ppm.

In the method of the present invention, an aromatic compound to be oxidized is converted to a molecular oxygen in a reaction solvent containing an aliphatic carboxylic acid, preferably a lower aliphatic carboxylic acid, in the presence of the catalyst in the oxidation reactor. By performing liquid phase oxidation with the contained gas, crystals of the aromatic carboxylic acid are precipitated to form a slurry.

The molecular oxygen-containing gas includes, for example, oxygen and air, but practically, air is preferably used. The molecular oxygen-containing gas is supplied in excess of the amount required to oxidize the aromatic compound serving as the oxidation raw material to the aromatic carboxylic acid. When air is used as the molecular oxygen-containing gas, aromatic compound 1 serving as an oxidation raw material
2 to 20 Nm ³ , preferably 2.5 to 15 kg / kg
It is desirable to supply Nm ^{3 to} the reaction system at a ratio of Nm ³ .

Specific examples of the lower aliphatic carboxylic acid used as the reaction solvent include acetic acid, propionic acid and butyric acid. The lower aliphatic carboxylic acid can be used alone as a reaction solvent, or can be mixed with water and used as a reaction solvent in the form of a mixture. Specific examples of the reaction solvent include, for example, acetic acid, propionic acid, butyric acid and mixtures thereof,
Alternatively, a mixture of these lower aliphatic carboxylic acids and water can be used. Among these, a mixture of acetic acid and water is preferable, and a mixture of 1 to 20 parts by weight of water, preferably 5 to 15 parts by weight of water is particularly desirable with respect to 100 parts by weight of acetic acid.

The temperature of the oxidation reaction is usually 100 to 250 ° C.,
Preferably, the range of 150 to 220 ° C is desirable. Also,
The reaction pressure may be any pressure as long as the reaction system can be maintained in a liquid phase.

By reacting in this manner, an aromatic carboxylic acid corresponding to the aromatic compound serving as an oxidation raw material is obtained. Specific examples of aromatic carboxylic acids include aromatic dicarboxylic acids such as terephthalic acid, isophthalic acid, 2,6-naphthalenedicarboxylic acid, and 4,4'-biphenyldicarboxylic acid; and aromatic dicarboxylic acids such as trimellitic acid and trimesic acid. Aromatic tricarboxylic acids such as pyromellitic acid; and the like.

The method of the present invention is preferably applied to the production of an aromatic dicarboxylic acid or an aromatic carboxylic acid which is insoluble or hardly soluble in a reaction solvent, and is particularly preferably applied to the production of terephthalic acid.

The generated aromatic carboxylic acid such as terephthalic acid precipitates as crystals and forms a slurry. The slurry is extracted from the oxidation reactor and the crystals are collected by solid-liquid separation to obtain crude terephthalic acid and the like. Things are obtained. Oxidation reaction intermediates and impurities are entrained in the crystals of the crude product thus obtained, and the crude product is dissolved and subjected to purification steps such as oxidation treatment and reduction treatment to produce terephthalic acid in a crystallization tank or the like. When crystals are precipitated and crystals are recovered from the slurry, a purified product of purified terephthalic acid is obtained.

According to the present invention, in the above-mentioned method for producing an aromatic carboxylic acid, there is provided a stirrer having an agitating blade on an upper surface portion of a rotating disk disposed substantially horizontally and having no agitating blade on a lower surface portion. The reaction is carried out using an oxidation reactor arranged at the bottom of the tank. The stirrer is preferably a disk turbine blade-type stirrer, in which stirring blades are radially provided on the upper surface of the disk. The disks are preferably arranged substantially horizontally at a height which is 1/3 to 1/2 the radius of the vessel below the boundary between the straight and curved sections of the vessel, the diameter being one of the diameter of the vessel. About な い し to 、, a flat plate is preferable, but a spherical surface or another curved surface may be used.
Further, it is preferable that a hole is not formed, but the hole may be formed.

The stirring blade is preferably a flat plate, but may be a half-cylindrical tube or another curved plate. The stirring blade is preferably provided perpendicularly to the upper surface of the disk and in the radial direction, but may be provided inclined with respect to the disk. The horizontal width of each stirring blade is preferably about 約 of the disk diameter when, for example, there are six stirring blades. It is preferable that the outer tip of the stirring blade be substantially equal to the diameter of the disk so as to coincide with the outer periphery of the disk, and it is better not to project from the outer periphery. The inside of the agitating blade can be extended inward as far as necessary for agitation, but preferably up to about 1/3 of the disk diameter.

The above-mentioned stirrer is preferably arranged at the lower part of the oxidation reactor, and is provided so that the rotating shaft extends downward from the lower surface of the disk and penetrates the bottom wall of the oxidation reactor and is connected to the driving device. . The above stirrer may be provided only in one stage below the reactor, or may be provided in a plurality of stages as necessary.

As the driving device, a hydraulic motor such as a hydraulic motor or a pneumatic motor is preferable because of low vibration, but an electric motor or the like may be used. When a pneumatic motor is used, oxygen gas (air) compressed by a compressor or oxidation exhaust gas can be used as a drive source.

It is preferable to provide a baffle plate on the inner peripheral wall of the oxidation reactor. From the viewpoint of preventing crystal adhesion, the baffle plate should be set at a height that is equal to the height of the radius of the tank from the boundary between the straight part and the curved part of the tank that is not directly affected by the flow created by the stirring blade. It is good to Although the number of baffles is not particularly limited, four baffles should be arranged at equal intervals on the tank wall in the circumferential direction of the tank.
It is preferable to arrange about 6 sheets.

In order to carry out an oxidation reaction using such an oxidation reactor, the average particle size of the crystals constituting the slurry in the tank is 500 μm or less, preferably 10 to 300 μm, more preferably 50 to 200 μm. By controlling the supply of raw materials, reaction conditions, removal of slurry, and the like so that the concentration of γ is maintained at 60% by weight or less, preferably 10 to 55% by weight, and more preferably 20 to 50% by weight, precipitation of crystals and The reaction can be performed while preventing adhesion.

The slurry containing crystals having such a particle size and concentration is １ ／ or less, preferably １ ／ or less, below the height of the liquid phase portion (liquid phase portion at the time of gas injection) of the oxidation reactor. Particularly preferably, by merely providing a stirrer in a portion of 1/5 or less, stirring can be performed to such an extent that settling and adhesion are sufficiently prevented. The rotation speed of the stirrer is 20 to 120 rpm, preferably 30 to 115 rpm, and the peripheral speed is 0.5 to 15 m / sec.
Preferably it is about 3 to 10 m / sec.

In order to stir the liquid in the tank by blowing an oxygen-containing gas in addition to stirring by the stirrer,
An oxygen-containing gas blowing part can be opened at the lower part of the stirrer. In this case, a plurality of blowing sections are opened at intervals so as to prevent the oxygen-containing gas from flowing into the tank without being involved in stirring (blowing) below the stirring blade at the bottom of the tank. Preferably, the bubbles are subdivided. At that time, the stirrer is installed such that the outer peripheral portion is located inside the oxygen-containing gas blowing portion. When the blade tip of the stirrer comes out of this range, the inflow of the oxygen-containing gas is blocked, and the blown oxygen-containing gas is pushed back to the lower side of the disk of the stirrer, so that the oxygen concentration tends to increase locally. If the blade tip of the stirring blade is smaller than this range, the oxygen-containing gas blows through and the bubbles cannot be fragmented.

The height of the liquid phase of the oxidation reactor is 1.5 times the diameter.
The amount of oxygen-containing gas (air) is 2,000 to 9000 Nm ³ / m ² / h at the superficial velocity per unit sectional area of the oxidation reactor based on the capacity before the reaction.
r, preferably 3500~4500Nm by a ³ / m ² / hr, it can be uniformly mixed and stirred-tank liquid there is no blow-gas.

According to the production method of the present invention, an oxidizing raw material, a catalyst and a solvent are supplied to a oxidizing reactor from a raw material supply path, an oxygen-containing gas is introduced from a gas introducing path through a gas blowing section, and the reaction is carried out while stirring with a stirrer. Do. Thereby, the alkylaromatic compound as a raw material is oxidized to generate an aromatic carboxylic acid.
As the reaction proceeds, the aromatic carboxylic acid becomes supersaturated and precipitates, and is stirred by a stirrer to frequently contact the reaction solution to grow crystals, and the slurry is partly taken out and sent to a purification step.

The purpose of installing the stirrer in the production method of the present invention is to uniformly stir and mix the liquid in the tank, to make the reaction or the precipitation of crystals uniform, and to prevent adhesion to the equipment. In the oxidation reactor, the raw material, the solvent, the catalyst and the enzyme are uniformly mixed and reacted, and the generated aromatic carboxylic acid is brought into contact with the crystal to promote the precipitation.

When a stirrer having stirring blades on the lower surface of the disk is used, the swirling flow generated below the disk of the stirrer causes the blown oxygen-containing gas to be caught under the disk, and the oxygen concentration is locally increased. Rises to precipitate crystals, and the crystals tend to adhere from the lower part of the disk to the rotating shaft and the baffle plate.

On the other hand, in the present invention, a stirrer having a stirring blade on the upper surface of a rotating disk disposed substantially horizontally and having no stirring blade on the lower surface is disposed at the bottom of the tank. By carrying out the reaction using the oxidation reactor, it is possible to prevent the deposition and deposition of crystals inside the oxidation reactor including the stirrer and the baffle plate. In this case, since there is no stirring blade on the lower surface of the disk, the blown oxygen-containing gas is not directly caught under the disk. The stirrer sucks the reaction solution from the upper part of the tank to the center of the upper surface of the disk by rotation, sends it out to the peripheral direction by the stirring blade, and circulates through the reactor.

The blown oxygen-containing gas is sent out in the outer circumferential direction by stirring, and is mixed with the reaction solution and circulated.
Therefore, a portion having a high oxygen concentration is not locally generated in the stirrer, and crystals are prevented from depositing on the stirrer or other vessel walls. If the oxygen-containing gas blowing portion is provided outside the outer peripheral portion of the stirrer, the tendency is further increased.
If the outer tip of the stirring blade protrudes from the disk, a swirling flow will also occur below the disk, and the injected oxygen-containing gas will easily collide with the lower part of the disk, but the stirring blade will not protrude from the outer periphery of the disk. The use of a stirrer prevents this and reduces the precipitation of crystals on the stirrer.

[0036]

According to the present invention, a stirrer having a stirring blade on the upper surface of a rotating disk arranged substantially horizontally and having no stirring blade on the lower surface is arranged at the lower part of the tank. By performing the reaction using the oxidation reactor, sedimentation and adhesion of the crude aromatic carboxylic acid crystal can be prevented, and the aromatic carboxylic acid can be stably produced.

[0037]

Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 is a vertical sectional view showing an oxidation reactor of an embodiment of the present invention, FIG. 2 is a sectional view taken along line AA of FIG.
3 denote the same or corresponding parts.

In FIG. 1, the oxidation reactor 1 is formed in a vertical cylindrical shape, and the tower diameter is 1.5 to 8 times the height of the liquid phase portion 13 when the oxygen-containing gas is blown. A baffle plate 2 is provided on the inner wall of. The baffle plate 2 is mounted by the mounting portion 2a from the viewpoint of preventing the adhesion of crystals, so that the height of the baffle plate 2 is the height of the radius of the tank from the boundary line L between the linear portion and the curved portion of the oxidation reactor 1 as the upper end. ing. Baffle plate 2
Six pieces are arranged so as to be arranged at equal intervals on the tank wall in the circumferential direction of the tank.

The stirrer 3 is 1 /
3 is provided at the lower portion of the disk 3a and is substantially horizontally arranged and rotates. The disk 3a has a stirring blade 3b on the upper surface thereof and a disk turbine blade having no stirring blade 3b on the lower surface. Is attached to the tip of the stirring shaft 4 extending from the driving device 5 composed of a fluid pressure motor through the lower wall 9 of the oxidation reactor 1, and is disposed only one stage below the tank. It is configured to rotate at intervals. The stirring blade 3b is provided so as not to protrude from the outer periphery of the disk 3a. The raw material supply path 6 communicates with a raw material supply section 10, and the slurry extraction path 8 communicates with a slurry extraction section 11 provided below. The oxygen-containing gas introduction path 7 communicates with the oxygen-containing gas injection section 12,
The disk 3 a of the stirrer 3 is arranged inside the oxygen-containing gas blowing section 12. An exhaust gas take-out part is provided at the upper part of the oxidation reactor 1, and the exhaust gas path is connected, but not shown.

In the method for producing an aromatic carboxylic acid, an oxidizing raw material, a solvent and a catalyst are continuously supplied from a raw material supply path 6 to a raw material supply section 10 to an oxidation reactor 1, and an oxygen-containing gas introduction path 7 is supplied through an oxygen-containing gas introduction path 7. The oxygen-containing gas is blown through the blowing unit 12 and the stirring is performed by rotating the stirrer 3 having the stirring blades 3b to cause an oxidation reaction. In this case, since the stirring blade is not provided on the lower surface of the disk 3a, the blown oxygen-containing gas is not directly caught below the disk 3a. For this reason, the stirrer 3 rotates the disc 3
The reaction liquid is sucked from the upper part of the tank to the center of the upper surface of the disk 3a and sent out to the peripheral direction by the stirring blade 3b without generating a strong swirling flow (c in FIG. 3) below the a. And circulate through the reactor.

The blown oxygen-containing gas is sent to the outer peripheral direction by stirring, and is mixed with the reaction solution and circulated.
Therefore, a portion having a high oxygen concentration is not locally generated in the stirrer 3, and the crystal is formed by the stirrer 3, the rotating shaft 4, the baffle plate 2.
Etc. are prevented from being deposited on the surface. If the outer tip of the stirring blade 3b protrudes from the disk 3a, a swirling flow also occurs below the disk 3a, and the injected oxygen-containing gas easily collides with the lower portion of the disk 3a. Stirrer 3 that does not protrude from the outer periphery of disk 3a
This is prevented, and the precipitation of crystals on the surfaces of the stirrer 3, the rotating shaft 4, the baffle plate 2 and the like is small.

The reaction solution in the oxidation reactor 1 is stirred by the oxygen-containing gas and uniformly mixed, so that the oxidation reaction is performed efficiently. On the other hand, the generated crystal slurry is prevented from sticking by being stirred by the stirrer 3 and the crystal grows by increasing the frequency of contact with the reaction solution. At this time, by setting the average particle diameter of the crystal to 500 μm or less and the concentration to 60% by weight or less, the reaction can be sufficiently prevented even by the stirrer 3 provided with the one-stage stirring blade 3b. The aromatic carboxylic acid generated by the oxidation reaction becomes crystals to form a slurry, and is passed through the slurry outlet 11 through the slurry outlet 8.
And sent to the purification process. The steam generated by the oxidation reaction and the consumed gas are discharged from an exhaust gas passage (not shown).

In the above description, the case where the present invention is applied to the oxidation reactor 1 has been described. However, the present invention can be applied to a crystallization tank or the like used in a purification step. In addition, a heat exchanger or a distillation column may be provided at the upper part of the oxidation reactor 1, or these may not be provided, and another device may be provided.

Although the present invention is suitable for producing terephthalic acid, it can be applied to the production of other aromatic carboxylic acids.

[Brief description of the drawings]

FIG. 1 is a vertical sectional view of an oxidation reactor according to an embodiment.

FIG. 2 is a sectional view taken along line AA of FIG.

FIG. 3 is a vertical sectional view showing a part of a conventional oxidation reactor.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Oxidation reactor 2 Baffle plate 2a Attachment part 3 Stirrer 3a Disk 3b Stirrer blade 4 Stirring shaft 5 Drive device 6 Material supply path 7 Oxygen-containing gas introduction path 8 Slurry removal path 9 Lower wall 10 Material supply section 11 Slurry removal section 12 Oxygen Gas containing part 13 Liquid phase part

──────────────────────────────────────────────────続 き Continued on the front page (51) Int.Cl. ⁷ Identification symbol FI Theme coat ゛ (Reference) B01D 9/02 614 B01D 9/02 614 618 519A B01J 19/00 321 B01J 19/00 321 19/18 19 / 18 C07C 63/14 C07C 63/14 // C07B 61/00 C07B 61/00 C 300 300 (72) Inventor Michio Umeda 1-2-1, Waki, Waki-machi, Kuga-gun, Yamaguchi Prefecture F-term in Mitsui Chemicals, Inc. (Reference) 4G075 AA02 AA22 AA35 BA10 BD13 BD16 CA54 DA01 EB01 EC01 EC09 EC11 ED08 4H006 AA02 AA04 AC46 BA16 BA20 BA34 BA37 BA45 BB17 BC32 BD81 BE30 BJ50 BS30 4H039 CA65 CC30

Claims (5)

[Claims] 1. A method for producing an aromatic carboxylic acid crystal by subjecting an alkyl aromatic compound to liquid phase oxidation with an oxygen-containing gas in a reaction solvent containing an aliphatic carboxylic acid in an oxidation reactor in the presence of an oxidation catalyst. A stirrer having an agitator on the upper surface of a rotating disk that is disposed substantially horizontally and having no agitator on the lower surface performs a reaction using an oxidation reactor arranged at the bottom of the tank. A method for producing an aromatic carboxylic acid, comprising: 2. The method according to claim 1, wherein the oxidation reactor has a plurality of oxygen-containing gas injection sections below the stirrer. 3. The method according to claim 1, wherein the stirring blade is provided so as not to protrude from the outer periphery of the disk. 4. The method according to claim 2, wherein the disk of the stirrer is located inside the oxygen-containing gas inlet. 5. The method according to claim 1, wherein the oxidation reactor has a baffle on an inner wall of a portion corresponding to the stirrer.