JPH04288040A - Production of naphthalenedicarboxylic acid - Google Patents

Abstract

PURPOSE:To obtain naphthalenedicarboxylic acid useful as a raw material for polyethylene naphthalate from diisopropylnaphthalene advantageously on an industrial scale in high yield and purity at a low production cost compared with conventional process. CONSTITUTION:Naphthalenedicarboxylic acid is produced by the liquid-phase oxidation of diisopropylnaphthalene with an O2-containing gas in acetic acid solvent. The above reaction is carried out by using a catalyst composed of (Cu and Br), (Cu, Br and Mn), (Cu, Br, Mn and Y) or (Cu, Br and Y) (Y is one or more kinds of heavy metal element selected from V, Fe, Co, Ni, Pd and Ce) (the atomic ratios of Br, Mn and Y to Cu is 0.1-100/1, respectively) preferably at 150-20 deg.C and 5-50kg/cm<2> pressure. An inexpensive copper-based catalyst can be used in the present process and the yield of the objective compound can be improved by using a small amount of the catalyst compared with the conventional expensive Co-based catalyst. Furthermore, the formation of the undesirable by-product such as trimellitic acid can be decreased.

Description

[Detailed description of the invention]

0001

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for producing naphthalene dicarboxylic acid by oxidizing diisopropylnaphthalene in an acetic acid solvent using a molecular oxygen-containing gas.

0002

[Prior Art] Conventionally, polyethylene naphthalate made of 2,6-naphthalene dicarboxylic acid and 2,6-ethylene glycol has been found to have better mechanical strength, heat resistance, and dimensional stability than polyethylene terephthalate made from terephthalic acid. It is known that it provides films and various molded products with excellent properties.

[0003] Therefore, as a method for producing 2,6-naphthalene dicarboxylic acid (hereinafter abbreviated as 2,6-NDA), for example, A method is known in which diisopropylnaphthalene is oxidized with molecular oxygen in an acetic acid solvent in the presence of a catalyst system consisting of cobalt, manganese, and bromine (Japanese Patent Publication No. 48-27318, Japanese Patent Publication No. 56
-3337 publication, JP-A-61-140540 publication,
JP-A-62-212345, JP-A-64-3148, JP-A-1-160943, JP-A-1-28
Publication No. 7055, etc.).

[0004] On the other hand, methods for producing aromatic carboxylic acids are disclosed in ■JP-A-52-77022;
Publication No. 56694 and the like are known.

[0005]

[Problems to be Solved by the Invention] However, in the method (2), the production of undesired by-products such as tar-like substances and benzene ring cleavage products such as trimellitic acid is suppressed, and the 2,6- In order to improve the NDA yield, it is necessary to use a large amount of catalyst relative to the raw materials at the start of the reaction. For this reason, as an industrial production method, operations such as separation and recovery of the catalyst after the reaction are complicated, and many purification steps are required to obtain highly pure 2,6-NDA. There are problems such as:

[0006] In addition, in the method (2), in an acetic acid solvent,
It is stated that in the production of terephthalic acid using a catalyst system consisting of cobalt, manganese and bromine, the addition of trace amounts (ppm) of copper suppresses the oxidative decomposition of the acetic acid solvent. does not enhance the catalytic reaction and is unlikely to contribute to the catalytic reaction. Also, 2,
There is no description regarding 6-naphthalene dicarboxylic acid.

On the other hand, method (2) describes a method for producing terephthalic acid using a catalyst system consisting of copper and bromine in an aqueous solvent, but the yield of terephthalic acid (molar yield)
is about 70% at most, and there is no description of 2,6-NDA.

[0008] Thus, it cannot be said that a method for producing 2,6-NDA in high yield from diisopropylnaphthalene using the above-mentioned conventional catalyst has yet been established.

[0009] Accordingly, an object of the present invention is to provide a method for producing naphthalene dicarboxylic acid in high yield and purity using diisopropylnaphthalene as a raw material.

0010

[Means for Solving the Problems] In order to solve the above problems, the present inventors have developed various catalyst systems as oxidation catalysts in a method for producing naphthalene dicarboxylic acid (hereinafter abbreviated as NDA) from diisopropylnaphthalene. Studies have shown that using a catalyst system consisting of copper and bromine or a catalyst system consisting of copper, bromine and heavy metals, compared to a catalyst system based on a traditionally used catalyst system consisting of cobalt, manganese and bromine. The present inventors have discovered that the desired NDA can be obtained in high yield and purity with a small amount of catalyst, and have completed the present invention.

That is, the present invention is a method for producing NDA in which diisopropylnaphthalene is used as a raw material and is oxidized in a liquid phase with a molecular oxygen-containing gas in an acetic acid solvent. It is characterized by causing a reaction.

The above-mentioned catalyst system is a catalyst system consisting of copper and bromine (hereinafter referred to as the first catalyst system), a catalyst system consisting of copper, bromine and manganese (hereinafter referred to as the second catalyst system), or a catalyst system consisting of copper, bromine and manganese. and Y (Y is a selected heavy metal other than manganese) (hereinafter referred to as the third catalyst system); a catalyst system consisting of copper, bromine, and Y (Y is a selected heavy metal other than manganese) (hereinafter referred to as the third catalyst system); , the fourth catalyst system).

[0013] Examples of the copper contained as a catalyst component include salts of copper with carboxylic acids such as formic acid, acetic acid, and naphthenic acid, organic compounds such as acetylacetonate complexes of copper, hydroxides, and oxides. , chlorides, bromides, nitrates, sulfates, and other inorganic compounds. Note that these copper salts may be anhydrous salts or hydrated salts.

[0014] As bromine, various bromine compounds,
Examples include hydrogen bromide, ammonium bromide, metal bromides, and the like.

[0015] Furthermore, examples of manganese include salts similar to the above-mentioned copper compounds.

[0016] The heavy metal designated as Y is
It is one or more heavy metal elements selected from the group consisting of vanadium, iron, cobalt, nickel, palladium, and cerium, and examples of the compound used include salts similar to the above-mentioned copper compounds.

As for the component ratio of each catalyst system, first,
The atomic ratio of copper and bromine in the catalyst system is copper:bromine=1
:a is in the range of 0.1≦a≦100, more preferably in the range of 1≦a≦40.Next, the atomic ratio of copper, bromine and manganese in the second catalyst system is copper:bromine: When manganese=1:a:b, 0.1≦a≦100, 0.
The range of 1≦b≦100, more preferably 1≦a≦40,
The range is 1≦b≦40.

Further, the atomic ratio of copper, bromine, manganese and Y in the third catalyst system is copper:bromine:manganese:Y=1:
If a:b:c, 0.1≦a≦100, 0.1≦b
The range is ≦100, 0.1≦c≦100, more preferably 1≦a≦40, 1≦b≦40, 1≦c≦40. Furthermore, the atomic ratio of copper, bromine, and Y in the fourth catalyst system is 0.1≦a, assuming that copper:bromine:Y=1:a:c
The range is ≦100, 0.1≦c≦100, and more preferably the range is 1≦a≦40, 1≦c≦40.

On the other hand, the specific steps in the method for producing NDA according to the present invention are carried out in a liquid phase as follows.

(A) Add acetic acid as a solvent, diisopropylnaphthalene as a raw material, and a catalyst in predetermined amounts to a reaction tank, supply a molecular oxygen-containing gas, and use this gas under pressure with stirring at a predetermined temperature. Make it react.

(B) Predetermined amounts of acetic acid and catalyst are respectively charged into a reaction tank, and while supplying a molecular oxygen-containing gas to the reaction tank,
Diisopropylnaphthalene is supplied continuously or intermittently, and the reaction is carried out at a predetermined temperature while stirring and under pressure with the above gas. In this case, a part of the raw material diisopropylnaphthalene may be added to the reaction tank in advance and the reaction may be carried out, or the reaction may be carried out continuously while part of the generated NDA is extracted.

In the present invention, the amount of catalyst relative to acetic acid as a solvent is 0.01 to 20% by weight based on the solvent.
, more preferably from 0.5 to 5% by weight. If the concentration is lower than this range, the activity will not be sufficiently exhibited, and if the concentration is higher than the upper limit concentration, it is undesirable because of limited solubility and an increase in by-products.

As the molecular oxygen-containing gas, oxygen or a mixed gas of oxygen diluted with an inert gas can be used, but from an industrial perspective, it is preferable to use air.

[0024] When using air, the reaction temperature is desirably within the range of 150 to 150° C., a temperature at which the reaction proceeds rapidly and at which a large amount of undesired by-products such as tar-like substances and carbonized substances are not produced. The temperature range is 220°C.

On the other hand, when using air, the reaction pressure may be any pressure that can maintain the liquid phase, and may be 5 to 50 kg.
/cm2 range, more preferably 10-40kg/c
m2 range. Examples will be described in more detail below, but the present invention is not limited thereto.

[0026] The conversion rate of the raw materials, the yield of NDA, and the yield of trimellitic acid (hereinafter abbreviated as TMA), which is an undesired by-product, in Examples and Comparative Examples shall be in accordance with the following definitions. do. In addition, the solvent and reagent used are JIS
A material of grade 1 or higher was used.

Conversion rate (%) = (Number of moles of raw material consumed) x 100 / (Number of moles of feedstock supplied) NDA yield (%) = (Number of moles of NDA produced) x 100 / (Number of moles of NDA produced) x 100 / (Number of moles of NDA produced) (Number of moles of raw material produced) TMA yield (%) = (Number of moles of TMA produced) x 10
0 / (number of moles of supplied raw material)

[0028]

[Example] [Example 1] The reaction in this example was as described above (
The reaction was carried out using method B). Specifically, 300 g of acetic acid as a solvent and copper acetate as an example of the first catalyst system were placed in a 1-liter titanium autoclave equipped with a stirrer, a cooler, a gas blowing pipe, a raw material supply line, and a constant differential pressure valve. [Cu(OAc)2] 2g and KBr3g
After preparing and heating to 190℃, 30kg/c with air
It was pressurized to m2.

Thereafter, while supplying a sufficient amount of air for oxidation and keeping the internal pressure at 30 kg/cm2, 60.0 g of 2,6-diisopropylnaphthalene (hereinafter abbreviated as 2,6-DIPN) was heated over 5 hours. After that, only air was fed for 1 hour to continue the reaction, and then the reaction was stopped.

When the reaction product was analyzed by liquid chromatography, as shown in Table 1, 2,6-DIP
The conversion rate of N was 100%, the yield of 2,6-NDA was 70%, and the T
The MA yield was 27%.

[Examples 2 to 19] The reactions in each of Examples 2 to 19 were carried out by the method (B) above. Specifically, as shown in Table 1, the catalyst components and their composition ratios as well as the reaction temperature and reaction pressure were changed in the autoclave as shown in Table 1, and the other examples were changed. The reaction was carried out under the same conditions as in 1. The reaction conditions and results are shown in Table 1.

From the results of Experimental Examples 1 to 19, even when the amount of catalyst used is 15% or less based on the raw material, 2,6-ND
The yield of A was 70% or more, which clearly showed an improvement in the 2,6-NDA yield with a smaller amount of catalyst than before.

[Example 20] 2,7-diisopropylnaphthalene (hereinafter abbreviated as 2,7-DIPN) as a raw material other than 2,6-diisopropylnaphthalene 60.
0g was used. The same reaction as in Example 1 was carried out except that 250 g of acetic acid was used as the solvent and the components and composition ratios of the second catalyst system as shown in Table 2 were used as the catalyst. The reaction conditions and results are shown in Table 2.

[Example 21] In place of 2,7-DIPN used as a raw material in Example 20, 60.0 g of 1,4-diisopropylnaphthalene (hereinafter abbreviated as 1,4-DIPN) was used as a solvent. The same reaction as in Example 1 was carried out except that 250 g of acetic acid was used. The reaction conditions and results are shown in Table 2.

[Example 22] 2,7-DIP as a raw material
The reaction was carried out in the same manner as in Example 1 except for using 60.0 g of N, 250 g of acetic acid as a solvent, and the components and composition ratios of the third catalyst system shown in Table 2 as a catalyst. The reaction conditions and results are shown in Table 2.

[Example 23] In place of 2,7-DIPN used as a raw material in Example 22, 1,4-DIP
The reaction was carried out in the same manner as in Example 1 except that 60.0 g of N and 250 g of acetic acid were used as a catalyst. The reaction conditions and results are shown in Table 2.

[Comparative Example 1] A conventionally used catalyst system was compared with the catalyst system according to the present invention.

Example 1 except that 7.5 g of a catalyst system consisting of cobalt, manganese and bromine was used as the conventional catalyst system.
The reaction was carried out under the same conditions. The reaction conditions and results are shown in Table 3.

[0039] From this result, the 2,6-NDA yield was almost the same as the reported example, but as is clear from Tables 1 to 3, the obtained 2,6-NDA yield was The yield of TMA, which is an undesired by-product, is lower than in the example, and also higher. On the other hand, although not shown, the observation results indicate that the reaction product contains many tar-like substances that are considered to be by-products, and the resulting 2
, 6-NDA was also darkly colored.

[Comparative Example 2] In order to show that copper is an essential element in the components of each catalyst system in the method according to the present invention, in Example 2, copper acetate was not added, but in Example 2, copper acetate was not added. The reaction was carried out under the same conditions. The results are shown in Table 3.

This result clearly shows that the 2,6-NDA yield is lower than that of Example 2. This indicates that copper is an essential element of the catalyst system according to the present invention.

[0042]

[Table 1]

[0043]

[Table 2]

[0044]

[Table 3]

[0045]

Effects of the Invention According to the method of the present invention, by using diisopropylnaphthalene as a raw material and using an inexpensive copper-based catalyst, the desired production can be achieved with a smaller amount of catalyst than when using a conventional expensive cobalt-based catalyst. The yield of naphthalene dicarboxylic acid is improved, while the production of undesired by-products such as trimellitic acid is reduced. Therefore, it is possible to produce naphthalene dicarboxylic acid industrially advantageously at lower production cost, higher yield, and higher purity than in the past.

Claims (5)

[Claims] Claim 1: Diisopropylnaphthalene in an acetic acid solvent,
In a method for producing naphthalene dicarboxylic acid in which liquid phase oxidation is performed using a molecular oxygen-containing gas, copper and bromine (the atomic ratio of copper and bromine is 0.1 when copper:bromine = 1:a)
≦a≦100) A method for producing naphthalene dicarboxylic acid, the method comprising: 2. The catalyst system comprises copper, bromine and manganese (copper, bromine and manganese).
The atomic ratio of bromine and manganese is copper:bromine:manganese=
If 1:a:b, 0.1≦a≦100, 0.1≦b
≦100).The method for producing naphthalene dicarboxylic acid according to claim 1. 3. The catalyst system comprises copper, bromine, manganese and Y(
Y represents one or more heavy metal elements selected from the group consisting of vanadium, iron, cobalt, nickel, palladium, and cerium, and the atomic ratio of copper, bromine, manganese, and Y is copper:bromine:manganese:Y=1: If a: b: c,
0.1≦a≦100, 0.1≦b≦100, 0.1≦c
≦100).The method for producing naphthalene dicarboxylic acid according to claim 1. 4. The catalyst system comprises copper, bromine and Y (Y represents one or more heavy metal elements selected from the group consisting of vanadium, iron, cobalt, nickel, palladium and cerium, and copper, bromine and Y atoms The ratio is copper:bromine:Y=1:
If a:c, 0.1≦a≦100, 0.1≦c≦1
00). The method for producing naphthalene dicarboxylic acid according to claim 1. 5. The method according to claim 1, 2, 3, or 4, wherein the oxidation reaction is carried out in a temperature range of 150 to 220°C and a pressure range of 5 to 50 kg/cm2. A method for producing naphthalene dicarboxylic acid.