JP2000037633A - Method for purifying crude aromatic dicarboxylic acid and catalyst to be used in purification - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a catalyst which can prevent poisoning by various kinds of metals in a method in which the purification of an aromatic dicarboxylic acid represented by terephthalic acid is performed by hydrogenating the dicarboxylic acid by using the catalyst in which a group VIII noble metal is supported on the carrier of granulated active carbon, and the life of the catalyst is prolonged and a method for purifying a crude aromatic dicarboxylic acid which can implement industrially advantageously by using the catalyst. SOLUTION: A catalyst is prepared by using a granulated active carbon at least 800 m2/g in total surface area, at least 0.6 ml/g in total fine pore volume, at least 0.2 ml/g in macro-pore volume, at most 1000 ppm in sulfur content as a carrier and supporting a group VIII nobel metal represented by palladium on the carrier. The purification of an aromatic dicarboxylic acid is performed by a hydrogenation treatment in which hydrogen gas is reacted with the crude dicarboxylic acid obtained by oxidizing an dialkyl aromatic compound in a liquid medium in the presence of the catalyst.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

[0001] The present invention relates to a method for purifying a crude aromatic carboxylic acid obtained by oxidizing a dialkyl aromatic compound, and a catalyst used for the purification.

[0002]

2. Description of the Related Art Aromatic dicarboxylic acids are important chemical products, and are widely used as raw materials for polymers such as synthetic resins. For example, terephthalic acid, which is a typical benzenedicarboxylic acid, is a raw material for a polyester resin, and isophthalic acid is important as a modifier for a polyester resin. In addition, 2,6-naphthalenedicarboxylic acid is a raw material for highly functional polyester resins that has recently attracted attention. Terephthalic acid is industrially p
-Manufactured by liquid-phase oxidation of dialkylbenzene
(For example, JP-A-60-184043). The obtained crude terephthalic acid contains various impurities including 4-carboxybenzaldehyde (hereinafter abbreviated as “4-CBA”). Even if these impurities are trace amounts, they may cause a quality problem by coloring polyesters produced by polycondensation of terephthalic acid and glycols or reducing the degree of polymerization. is there.

[0003] Therefore, how to purify terephthalic acid containing impurities as described above is an important subject, and many solutions have been proposed so far. Above all, the method disclosed in U.S. Pat.No. 3,584,039 is based on purifying an aqueous solution of crude terephthalic acid with hydrogen in the presence of a supported or unsupported Group VIII noble metal catalyst. This is an excellent method in which 4-CBA and other coloring impurities contained in crude terephthalic acid are removed as a removable compound to obtain fiber-grade high-purity terephthalic acid.

[0004] However, when a noble metal catalyst in which palladium is supported on conventional activated carbon is used (Japanese Patent Application Laid-Open No. 9-263565, etc.), the initial activity shows a very high value. In some cases, the surface was worn due to collision with water, or the palladium carried was peeled off, so that a decrease in catalytic activity was unavoidable. In addition, cobalt and manganese contained as impurities in the crude aromatic carboxylic acid, and iron generated by corrosion of the device,
Catalytic performance sometimes deteriorated due to poisoning by metals such as chromium.

In JP-A-9-263566, a specific granulated activated carbon, that is, a raw material such as charcoal, coconut shell charcoal, coal, coke, etc. is finely pulverized as a carrier for a catalyst, and a binder is added thereto. The use of granulated activated carbon succeeded in partially resolving the above drawbacks. However, depending on the type of granulated activated carbon, there is a problem that the catalytic activity is still significantly reduced.

[0006]

SUMMARY OF THE INVENTION An object of the present invention is to provide a method for resolving an aromatic dicarboxylic acid represented by terephthalic acid, which has solved the above-mentioned problems. Specifically, granulated activated carbon is used as a carrier,
In a purification method in which a hydrogenation treatment is carried out using a catalyst carrying a group noble metal, it is possible to prevent poisoning of various metals and to provide a catalyst having an extended life, and use of such a catalyst. To provide a method for purifying a crude aromatic dicarboxylic acid which can be carried out industrially advantageously.

[0007]

The catalyst used in the purification of the crude aromatic dicarboxylic acid of the present invention has a total surface area of 800 m ² / g or more, a total pore volume of 0.6 ml / g or more, The catalyst is obtained by using granulated activated carbon having a pore volume of 0.2 ml / g or more and a sulfur content of 1000 ppm or less as a carrier, and supporting a Group VIII noble metal on the carrier.

In the method for purifying a crude aromatic dicarboxylic acid according to the present invention, hydrogen gas is reacted with a crude aromatic dicarboxylic acid obtained by oxidation of a dialkyl aromatic compound in a liquid medium in the presence of the above catalyst. And subjecting it to catalytic hydrogenation.

In these inventions, a granulated activated carbon having a specific physical property and having a low sulfur content is used as a carrier, and a catalyst in which a Group VIII noble metal is supported thereon is used as a catalyst compared with a conventional catalyst. Based on new findings obtained by the inventors that the catalyst is hardly deactivated and the life of the catalyst is long.

[0010]

DETAILED DESCRIPTION OF THE INVENTION In general, activated carbon has mesopores (pore diameter of 20 to 500 mm) on the inner wall of macropores (pore diameter> 500 mm).
Are distributed, and micropores (pore diameter <20 °) are distributed on the inner wall of the mesopores. In the present invention, as the granulated activated carbon used as the catalyst carrier, those having a large total surface area, highly developed macropores, and a large total pore volume are selectively used. In the present invention, "total surface area" using the value measured by N ₂ adsorption BET method, the term "macropore", pore size 200Å larger pore, namely the mesopores macropores as referred Normal respect charcoal It is a term that refers to pores that include those with larger pore diameters,
“Total pore volume” is a word meaning the volume of pores having pore diameters larger than 10 °.

The total surface area of the granulated activated carbon used as the catalyst carrier is as follows:
As described above, it must be 800 m ² / g or more. 10
It is preferably at least 00 m2 / g. If the total surface area is too small,
The surface area of the supported metal, which is the active component, is small, and the catalytic activity is low. Although the upper limit of the total surface area is not particularly limited, the total surface area of the activated carbon is theoretically about 2600 m2.
/ g is the limit.

[0012] The total pore volume is also 0.6
It is required to be at least ml / g, preferably 0.6 to 1.5 ml / g. The pore volume of the macropores (pore diameter> 200 °) is 0.2 ml / g or more, preferably 0.2 to 1.0 ml.
/ g. If the total pore volume and the macropore pore volume are too small, poisoning such as blockage and masking of pores caused by metal caused by corrosion of the device, which is a cause of catalyst deactivation, is likely to occur. Activity decreases quickly. The upper limit of both the total pore volume and the macropore pore volume is not particularly defined, but an activated carbon that is too large has insufficient strength as a catalyst carrier.

The granulated activated carbon capable of achieving the object of the present invention must have a sulfur content of 1000 ppm or less in addition to the above-mentioned physical form. 500p
It is preferably at most pm. Examples of granulated activated carbon with a low sulfur content include activated carbon that originally contains little sulfur, such as charcoal and coconut shell charcoal, and raw materials with a low sulfur content are finely pulverized and compounded with a binder that does not contain sulfur. Granulated activated carbon obtained by carbonizing and activating a granulated activated carbon produced by the above method and a thermosetting resin, specifically a phenol resin, as a raw material. The reason for suppressing the sulfur content is that it has been found that, under the reaction conditions, a noble metal such as palladium, which acts as a catalyst, is poisoned by the sulfur in the activated carbon and the activity is rapidly reduced. Therefore, the lower the sulfur content, the better, and the lower limit is not particularly defined.

The noble metal of Group VIII of the periodic table supported on the granulated activated carbon constituting the catalyst of the present invention is palladium, rhodium, ruthenium, osmium, iridium,
And one or more of platinum. Preferred metals are platinum, palladium, rhodium, and ruthenium. Excellent results are obtained especially with palladium. The loading amount of the noble metal is suitably 0.1 to 5% by mass based on the total amount of the catalyst, and 0.1 to 1% by mass.
% By mass is preferred.

The production of the catalyst may be performed according to generally known techniques. The most typical method is to prepare an activated carbon satisfying the conditions of the desired total surface area, total pore volume, macropore pore volume and sulfur content as described above in a solution of a compound containing a salt of a Group VIII metal. This is an impregnation method in which immersion is performed for a period of time to day and night. Examples of noble metal salts include palladium, rhodium, ruthenium and platinum chlorides, bromides, nitrates, amine salts, ammonium salts and the like. The catalyst is obtained by lifting the support impregnated with the metal salt from the salt solution, washing and drying under vacuum.

The crude aromatic dicarboxylic acids to which the purification method of the present invention can be applied include, as one part, a dialkyl aromatic having two or more alkyl substituents or partially oxidized alkyl substituents on two aromatic rings. It is obtained by oxidizing a compound, and the alkyl substituent is typically a lower alkyl group having 1 to 3 carbon atoms such as methyl, ethyl, propyl, and isopropyl. Partially oxidized alkyl substituents include oxygen-containing hydrocarbon groups other than carboxyl groups, such as aldehyde groups and hydroxyalkyl groups.

Such a crude aromatic dicarboxylic acid has the structure of o-
It can be obtained by using xylene, m-xylene, p-xylene, p-toluic acid, 2,6-dimethylnaphthalene, 2,7-dimethylnaphthalene, or the like as a starting material, and oxidizing it as a gas or liquid phase. Preferred is a crude product of benzenedicarboxylic acid obtained by oxidizing the above starting material in a liquid phase with molecular oxygen using a catalyst such as cobalt, manganese, or bromine with a lower aliphatic carboxylic acid as a reaction medium. It is. Examples of such crude products include crude terephthalic acid and crude isophthalic acid by the production method described in JP-A-60-184043. This method for producing terephthalic acid uses a catalyst obtained by adding para-xylene or meta-xylene to a cobalt or manganese salt (0.1 to 1% by weight as a metal atom) and a bromine compound (0.3 to 10% by weight as a bromine atom). Oxidizing in a liquid phase using a gas containing molecular oxygen in an acetic acid solution containing 1 to 10 moles of an aromatic carboxylic acid with respect to all metal atoms in the presence of Characterized in that calcium bromide and tetrabromoethane are used.

The reaction medium used in the purification method of the present invention comprises:
It is an aqueous medium, that is, a medium containing water or water as a main component and an organic solvent added thereto. An example of the latter is an aqueous acetic acid solution. However, it is generally sufficient to use water such as distilled water or ion-exchanged water. The amount of reaction medium used is such that it dissolves the crude aromatic dicarboxylic acid at least partially, preferably completely, at the reaction temperature. Usually, an amount of 2 to 20 times the weight of the crude product is used.
Three to ten times the amount is preferred. If the amount of the reaction medium is too small, it goes without saying that the amount of the crude aromatic carboxylic acid dissolved is small, and the purification by the hydrogenation reduction reaction is not sufficiently performed. If the amount is too large, the reaction may proceed,
It is economically disadvantageous, such as requiring a large reactor and increasing the energy consumption required for the recovery of the aromatic dicarboxylic acid.

The reaction temperature is selected so that the crude aromatic dicarboxylic acid is sufficiently dissolved in the reaction medium. At low temperatures, the solubility is low and a large amount of solvent is required. If the temperature is too high, undesirable decomposition reactions occur, such as elimination of carboxyl groups. Preferred temperatures are from 200 to 330C, particularly preferred temperatures are from 250 to 310C. The supply amount of hydrogen that reduces impurities to a compound that can be removed can be 1% based on the aromatic carboxylic acid having a formyl group represented by 4-CBA, which is present in the crude aromatic dicarboxylic acid. At least 1 mol is required per mol, and preferably 2 mol or more. If the supply amount of hydrogen is insufficient, decarboxylation of the aromatic dicarboxylic acid proceeds. On the other hand, when the amount of hydrogen is increased, the nuclear hydrogenation reaction of the aromatic ring proceeds. Therefore, the maximum is limited to 20 mol. For purification purposes, 10 mol or less is sufficient, and usually 2 to 7 mol is optimal. The partial pressure of hydrogen is suitably from 0.01 to 2 MPa, and from 0.1 to 1 MPa.
Is preferred.

The overall pressure in the reaction system is such that at least a part of the reaction medium can be in liquid form. 50% by mass
The above is preferably present in the liquid phase part, particularly preferably about 75% by mass. Since the pressure is affected by the temperature of the system, the partial pressure of hydrogen, and the type and amount of the reaction medium, it cannot be said unconditionally, but is usually 3 to 13 MPa.
A preferred range is from 5 to 10 MPa.

The appropriate amount of the catalyst used in the purification of the present invention is determined by conditions such as the reaction temperature, the concentration of impurities in the crude aromatic dicarboxylic acid, and the residence time in the reactor. The crude aromatic dicarboxylic acid to the noble metal component in the reduction catalyst is contained in a mass ratio of about 200: 1 to about 30
000: 1, preferably about 2000: 1 to about 2000
What is necessary is just to select and use it so that it may become 0: 1. If the amount of noble metal catalyst is small, the hydrogenation reaction rate of impurities is low and the effect of removing coloring impurities is inferior.On the other hand, the presence of an excessive amount of the catalyst may cause the decarboxylation of aromatic dicarboxylic acids and the removal of aromatic rings. It is not preferable because the nuclear hydrogenation reaction proceeds.

The reaction may be carried out continuously or in a batch operation.

The reaction time varies depending on the ratio of the crude aromatic dicarboxylic acid to the hydrogenation reduction catalyst, the hydrogen concentration and the reaction temperature. As a guide for actual operation, the residence time or feed weight velocity (WHSV) during which the reaction mixture is in contact with the hydrogenation reduction catalyst
About 200 to 200,000 g (reaction solution) / g (noble metal component in the hydrogenation reduction catalyst) · hr, preferably 100
It is 0 to 100,000 g / g · hr.

After the completion of the hydrogenation reduction treatment, the hydrogenation reduction catalyst present as a solid in the aqueous reaction medium is separated from the aromatic dicarboxylic acid dissolved in the medium.
If the reaction is carried out by a continuous method in which the catalyst is used as a fixed bed and the reaction solution is passed through it, solid-liquid separation of the catalyst and the reaction solution can be naturally performed.

Aromatic dicarboxylic acids are generally hardly soluble or almost insoluble in aqueous media at normal temperature and normal pressure, but have high solubility under high temperature and high pressure.
By subjecting the hydrogenation reduction catalyst and the reaction product liquid to solid-liquid separation by means such as centrifugation, a purified product can be taken out. The condition of high temperature and high pressure at which the aromatic dicarboxylic acid easily dissolves in the aqueous medium is that the temperature is 200 ° C. or more and the pressure is 3M
At least Pa, the solubility of the aromatic dicarboxylic acid in water is at least about 10% by mass under these conditions.
The practical limits are a temperature of 330 ° C. and a pressure of 10 MPa. A suitable range is a temperature of 250 to 310 ° C and a pressure of 7 to
It is 10 MPa.

Following the solid-liquid separation, the obtained reaction solution is cooled to crystallize the aromatic dicarboxylic acid. The crystallization temperature is between 200 ° C. and 30 ° C. Preferred temperatures are between 100 and 35 ° C. At this time, the cooling rate is preferably slow, 25 ° C. / min or less,
More preferably, it is 10 ° C./min or less. If the cooling rate is too high, the particles of the precipitated aromatic dicarboxylic acid will be extremely fine, making it difficult to separate from the mother liquor. The precipitated purified aromatic dicarboxylic acid is recovered by means such as filtration and centrifugation.

[0027]

EXAMPLES In the following examples, the purity was measured by high performance liquid chromatography (HPLC) using an analytical column: Bio-Sil C18 HL 90-5S (BIO-RAD) solvent: acetonitrile / 3% acetic acid aqueous solution. I did it. The hue was measured by measuring the L value of a powder sample prepared and filled in a cylindrical glass cell.
(Brightness), a value ((+) red to green (-)) and b value ((+) yellow to blue
(-)]. As the L value is closer to 100 and the a and b values are closer to 0, the hue is closer to white.

[Catalyst Production Example 1] Granulated activated carbon “Bellfine” (Kanebo Co., Ltd., particle diameter 2 mm) in the form of pellets was added to 0.1%.
The mixture was placed in a 02 mol aqueous solution of palladium nitrate, stirred at room temperature for 1 hour, filtered through a glass filter, and washed with distilled water. Washing is performed until the pH of the washing solution becomes about 5,
Then, it was vacuum dried. The dried product was reduced by heating at 300 ° C. for 4 hours in a stream of hydrogen.

The palladium carbon pellet catalyst thus prepared contained about 0.5% by mass of palladium, calculated as palladium metal, based on the dry catalyst composition. Analysis of the physical properties revealed a total surface area of 1150 m ² / g, a total pore volume of 0.705 ml / g, and a macropore pore volume of 0.304 ml / g. The sulfur content was 800 ppm.

[Catalyst Production Example 2] Granulated activated carbon "Bellfine" in pellet form (manufactured by Kanebo Co., Ltd., with a particle diameter of 3 mm)
Was placed in a 0.02 mol aqueous solution of palladium nitrate, stirred at room temperature for 3 hours, filtered through a glass filter, and washed with distilled water. Example 1 of cleaning, drying and reduction treatment
Was performed in the same manner as described above.

The palladium carbon pellet catalyst thus prepared contained about 0.5% by mass of palladium, calculated as palladium metal, based on the dry catalyst composition. Physical properties are 1200m ^{2 in} total surface area
/ g, the total pore volume was 0.639 ml / g, and the macropore pore volume was 0.227 ml / g. Sulfur content is 200ppm
Met.

COMPARATIVE EXAMPLE 1 As an example of a commercially available palladium carbon catalyst, a 0.5% palladium-supported carbon particle catalyst (crushed coconut shell charcoal 4-8 mesh, manufactured by NE Chemcat Co., Ltd.) was used. When analyzed for properties, the total surface area was 950 m ² / g, and the total pore volume was 0.578 ml / g.
g, macropore pore volume 0.178 ml / g, sulfur content 100 ppm.

Comparative Example 2 The properties of a commercially available 0.5% palladium-supported carbon small pellet catalyst (granulated activated carbon having a diameter of 2 mm, manufactured by NE Chemcat Co., Ltd.) were analyzed. 1200 m ² / g, total pore volume 1.046 ml / g, macropore pore volume 0.561 ml / g
And the sulfur content was 3400 ppm.

[Comparative Example 3]
When the properties of a 5% palladium-supported carbon large pellet catalyst (granulated activated carbon having a diameter of 4 mm, manufactured by NE Chemcat Co., Ltd.) were analyzed, the total surface area was 1,100 m ² / g, the total pore volume was 0.973 ml / g, 0.493 ml of macropore volume
/ g, the sulfur content was 1500 ppm.

[Example 1] Using the catalyst prepared in Example 1 and the catalyst of Comparative Example 1, purification was carried out by catalytic hydrogenation of a crude aromatic carboxylic acid. The effect on activity was investigated.

The evaluation was carried out in a titanium autoclave having a capacity of 300 cc in which no corrosion of the apparatus was observed under the reaction conditions, and a stainless steel autoclave having a capacity of 300 cc, in which it was confirmed that constant equipment corrosion occurred under the reaction conditions. And by measuring the situation where the catalytic activity of the hydrotreating decreases. The structure of each autoclave is as shown in FIG.

About 130 cc of water was put into the autoclave (1), and about 40 g of crude terephthalic acid (abbreviated as "CTA") containing 2500 ppm of 4-CBA was put therein, and the CTA aqueous solution (6) was added thereto. did. Next, hydrogen gas was injected so that the hydrogen partial pressure became 1.0 MPa. Thereafter, the mixture was heated by a mantle heater (2) to raise the temperature to 285 ° C., and then about 1 cc of the catalyst placed in the catalyst holder (about 0.1 cc).
5 g) was immersed in a CTA solution and reacted for 10 minutes.
This operation was repeated by renewing only the raw material CTA and the water of the reaction medium while keeping the catalyst as it was, and performing refining by batch operation by newly injecting hydrogen gas. As the number of reactions increases, 4-
The situation where the conversion of CBA to a removable compound was decreasing was recorded. The results are shown in Table 1 and FIG.

Table 1 4-CBA conversion of each catalyst Example 1 Comparative Example 1 Reactor Titanium made of stainless steel Titanium made of stainless steel Number of reactions 1 91.3 91.6 99.7 95.7 2 88.3 87. 0 92.6 90.2 3 84.8 85.6 91.8 87.0 4 83.5 83.0 89.0 84.5 5 81.7 81.5 88.2 80.8 6 80.3 80.1 87.5 77.5 units are% by mass.

From the data, it can be seen that the conversion rate of 4-CBA decreases drastically with each increase in the number of reactions in the catalyst of Comparative Example 1 when the stainless steel reactor was used, as compared with the case where the titanium reactor was used. You can see that On the other hand, in the case of the catalyst of Example 1, the decrease in the conversion of 4-CBA is only about the same as that in the case of using the stainless steel reactor and the case of using the titanium reactor. This is because the influence of the metal compound generated by the corrosion of the reactor on the catalytic activity was found in Comparative Example 1.
This shows that the catalyst of Example 1 was smaller than the catalyst of No. 1.

Example 2 With respect to the four types of catalysts of Catalyst Production Examples 1 and 2 and Comparative Examples 2 and 3, the effect of the sulfur content in the catalyst on the catalytic activity was measured. The four catalysts were first purified in the presence of hydrogen and terephthalic acid.
Aging was carried out in a 1.5 liter titanium autoclave for 2 hours.

About 40 g of CTA used in Example 1 and containing 2500 ppm of the impurity 4-CBA was suspended in about 130 cc of water in an autoclave. Hydrogen gas was injected into the autoclave so that the hydrogen partial pressure became 1.0 MPa. Set the temperature in the autoclave to 285
After the temperature was raised to about 0 ° C., about 1 cc (about 0.5 g) of the catalyst placed in the catalyst holder was immersed in the above solution and reacted for 20 minutes.
Table 2 shows the relationship between the sulfur content and the 4-CBA conversion.

Table 2 Relationship between sulfur content and 4-CBA conversion of each catalyst Sulfur content (ppm) 4-CBA conversion (% by mass) Catalyst Production Example 1 800 87.8 Catalyst Production Example 2 200 91. 9 Comparative Example 2 3400 45.7 Comparative Example 3 1500 56.5 From the data in Table 2, it can be seen that both of the catalysts of Catalyst Production Examples 1 and 2 have high 4-CBA conversion. In comparison, the catalysts of Comparative Examples 2 and 3 were both 4-CB
A conversion is much lower.

After the reaction of these catalysts, the distribution of palladium and the distribution of sulfur within the catalyst particles were examined by EPMA (Electron Probe Micro Analysis). While very little sulfur was attached to palladium, it was observed that a large amount of sulfur was attached to the catalysts of Comparative Examples 2 and 3 so as to cover palladium near the catalyst surface. The latter fact supports the understanding that the sulfur contained in the catalyst particles oozes out on the surface under the reaction conditions and adheres to the active ingredient palladium to reduce the activity. As described above, there is a close relationship between the sulfur content in the catalyst and the catalytic activity, and when the sulfur content exceeds a certain limit, the catalytic activity sharply decreases.

Example 3 Using the catalysts of Production Examples 1 and 2 and Comparative Example 1, purification of crude 2,6-naphthalenedicarboxylic acid by hydrogenation was carried out. First, as in Example 2, the three catalysts were added for 72 hours in the presence of hydrogen gas and 2,6-naphthalenedicarboxylic acid.
It was aged in a 1.5 liter titanium autoclave.

About 20 g of crude 2,6-naphthalenedicarboxylic acid containing 10000 ppm of 6-formyl-2-naphthoic acid (abbreviated as "6F-2NA") as an impurity was suspended in about 150 cc of water put in an autoclave. Turned cloudy.
Hydrogen gas was injected into the autoclave so that the partial pressure of hydrogen became 1.0 MPa. After the temperature in the autoclave was adjusted to 290 ° C., about 1 cc (about 0.5 g) of the catalyst placed in the catalyst holder was immersed in the solution and reacted for 20 minutes. Table 3 shows the conversion of 6F-2NA.

Table 3 6-Formyl-2-naphthoic acid conversion of each catalyst 6F-2NA conversion (% by mass) Example 1 90.5 Example 2 88.9 Comparative Example 1 92.2 Catalyst Preparation Example 1 The 6F-2NA conversion of the catalyst 2 was
Both are comparable to those of the catalyst of Comparative Example 1.

[Brief description of the drawings]

FIG. 1 is a longitudinal sectional view showing the structure of an apparatus used for testing the performance of a catalyst of the present invention.

FIG. 2 is a graph showing the relationship between the number of times of use of the catalyst and the conversion of 4-CBA, which is data of an example of the present invention.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Autoclave 2 Mantle heater 3 Stirrer shaft 4 Catalyst holder 5 Catalyst 6 Crude aromatic dicarboxylic acid aqueous solution

──────────────────────────────────────────────────の Continued on the front page (51) Int.Cl. ⁷ Identification symbol FI Theme coat ゛ (Reference) C07C 63/26 C07C 63/26 L (72) Inventor Hiroaki Otsuka 1134-2 Gongendo, Satte City, Saitama Kosmo Research Institute R & D Center (72) Inventor Hiroyuki Ueki 1134-2 Gondogendo, Satte City, Saitama Prefecture Cosmo Research Institute R & D Center (72) Kazuyuki Fujiki 1134 Gongendo, Satte City, Saitama Prefecture -2 In the R & D Center of Kosmo Research Institute Co., Ltd. (72) Inventor Mitsunobu Kimura 1134-2 Gongendo, Satte City, Saitama F-term in the R & D Center of Kosmo Research Institute Co., Ltd. 4G069 AA01 AA03 AA08 BA08A BA08B BC69A BC72B BD08A BD08B CB02 CB70 DA08 EA02Y EB18Y EC04X EC05X EC05Y EC07X EC07Y EC08X ED05 FA02 FB14 FB31 FB44 FC08 4H006 AA02 AD31 BA22 BA23 BA24 BA25 BA26 BA55 BB17 BB31 BE20 BJ50 BS30 4H039 CA65 CC30

Claims (2)

[Claims] 1. The total surface area is 800 m ² / g or more, the total pore volume is 0.6 ml / g or more, the macropore pore volume is 0.2 ml / g or more, and the sulfur content is 1000 ppm or less. A catalyst for use in the purification of a crude aromatic dicarboxylic acid, which comprises using activated carbon as a carrier and carrying a Group VIII noble metal thereon. 2. A catalytic hydrogenation treatment of a crude aromatic dicarboxylic acid obtained by oxidation of a dialkyl aromatic compound in a liquid medium by the action of hydrogen gas in the presence of the catalyst according to claim 1. A method for purifying a crude aromatic dicarboxylic acid, comprising: