JPH0640958A - Production of 2,6-dialkylnaphthalene - Google Patents

Abstract

PURPOSE:To provide a method capable of selectively producing a 2,6- dialkylnaphthalene in a high yield constantly over a long period. CONSTITUTION:In production of a 2,6-dialkylnaphthalene by transalkylation, isomerization or disproportionation of naphthalene or alkylnaphthalenes, the reaction is carried out in the presence of a zeolite catalyst prepared by treating a zeolite having >=10 silica/alumina (mol/mol) ratio with an acid and dealuminating it so as to increase this ratio by >=0.5. In the case of transalkylation, polyethylbenzene or polyethylnaphthalene is preferably used as the transalkylation agent. This invention can establish an effective method for producing a 2,6-dialkylnaphthalene by a technique of alkylation of naphthalene, capable of reducing deactivation of the catalyst and of exhibiting a stable activity in the fixed bed flow reaction. This method is, therefore, industrially significant.

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 2,6-dialkylnaphthalene useful as a raw material for 2,6-naphthalenedicarboxylic acid.

[0002]

2. Description of the Related Art 2,6-Naphthalenedicarboxylic acid is a substance useful as a polymer material, a dye intermediate or the like. In particular, polyester containing 2,6-naphthalenedicarboxylic acid as a constituent component is more heat resistant than polyethylene terephthalate,
It has excellent gas barrier properties and is attracting attention as a material for films and food packaging materials. 2,6-Naphthalenedicarboxylic acid is obtained by oxidizing 2,6-dialkylnaphthalene, and it is most important to obtain this 2,6-dialkylnaphthalene selectively and in good yield.

Alkylation of naphthalene using olefin has a problem in selectivity, and in the method using a Friedel-Crafts catalyst such as aluminum chloride as a catalyst, pitch is liable to occur, corrosion is liable to occur, and waste water treatment is difficult. There are problems such as difficulty.

A method for producing ethylnaphthalene by reacting naphthalene with ethylbenzene is described in US Pat. No. 4,873,386 and Bull. Chem. Soc. Jp.
n., 48 , 3306-3308 (1975), all of them use a Lewis acid that dissolves in the reaction system such as AlCl ₃ or AlCl ₃ as a catalyst, and therefore, to remove the catalyst after the reaction is completed. There are drawbacks such as the need for washing and neutralization steps, the generation of a large amount of acidic wastewater containing AlCl ₃ , the difficulty of continuous reaction, and the requirement for a reactor having a material with strong acid resistance. . Further, when a Lewis acid such as AlCl ₃ is used as a catalyst, there is a problem that pitching due to polymerization of naphthalene ring is severe.

US Pat. No. 5,001,295 describes a methylation reaction of 2-alkylnaphthalene with methanol using a zeolite catalyst, but the conversion is low and not industrial. JP-A-63-14,737 describes a method for producing methylnaphthalene by reacting naphthalene with methylbenzene using a solid acid catalyst such as Y-type zeolite. If a commercially available Y-type zeolite having a (mol / mol) of 10 or less is used as it is, it is difficult to obtain stable activity for a long period of time.

[0006] As described above, the catalysts which show stable activity for a long period in the alkylation reaction such as methylation and ethylation of naphthalene in the fixed bed flow reaction mode using industrially solid acid catalysts are as follows. Was not known.

[0007]

SUMMARY OF THE INVENTION Therefore, the object of the present invention is to alkylate naphthalene having a long-term stable activity, which can be used in a fixed bed flow reaction using a catalyst other than a Lewis acid such as AlCl ₃ . Efficient by technology 2,6
-To provide a method for producing a dialkylnaphthalene.

[0008]

[Means for Solving the Problems] That is, the present invention provides a method for producing a 2,6-dialkylnaphthalene by transalkylating, isomerizing or disproportionating naphthalene or an alkylnaphthalene in the presence of a zeolite catalyst. A 2,6-dialkylnaphthalene characterized by using as a catalyst a zeolite that has been dealuminated by acid treatment so that the silica / alumina ratio (molar ratio) becomes 10 or more and the ratio becomes 0.5 or more. It is a manufacturing method.

The manufacturing method of the present invention will be described in detail below. Examples of the type of zeolite used as a catalyst in the present invention include faujasite zeolite such as Y-type zeolite and X-type zeolite, pentasil-type zeolite such as ZSM-5, L-type zeolite and mordenite.
Zeolite having a pore size of 5.0 Å or more is preferable.
This is because after the de-aluminium treatment, the silica / alumina ratio (mol / mol) is 10 or more, and the NH ₃ differential heat of adsorption is 0.1 mol / k or more at an acid point of 85 kJ / mol or more.
It is preferable to have g or more, more preferably with respect to the amount of acid,
An acid point with a NH ₃ differential heat of adsorption of 85 kJ / mol or more is set to 0.
While having 1 mol / kg or more, 0.01 mol / k acid point with NH ₃ differential heat of adsorption of 130 kJ / mol or more
It has more than g. The definition of the heat of differential adsorption of NH ₃ is based on the literature: Bull. Chem. Soc. Jpn., 48 , 3576 (1975).

Zeolite catalysts having a pore size of 5.0 Å or less are not preferable because it is very difficult for naphthalene to enter the pores. Further, zeolite having a pore size of 7.2 Å or less, for example, L-type zeolite, mordenite, Z
When a transalkylation, isomerization or disproportionation reaction is performed using a pentasil-type zeolite such as SM-5, the reaction temperature is set to 35 in order to sufficiently diffuse each molecule into the pores.
It is preferably set to 0 ° C or higher. In addition, the acid point having a NH ₃ differential adsorption heat of 85 kJ / mol or more is 0.1 mol / k.
With a zeolite catalyst having only g or less, a sufficient reaction rate and reaction activity cannot be obtained, and industrial adoption is difficult. Suitable zeolites include faujasite type zeolites, especially Y type zeolites.

As the acid amount of these zeolite catalysts,
NH ₃ differential heat of adsorption is 3 m when the acid point is 85 kJ / mol or more.
Those having ol / kg or less are preferable. The number of acid points is 3mo
If it is more than 1 / kg, the deposition rate of carbonaceous matter becomes faster and the catalyst life becomes shorter. The zeolite catalyst that lost its activity is
It can be easily regenerated by removing carbonaceous substances by firing at about 500 ° C. with air diluted with nitrogen.

Zeolite is added to the silica / alumina ratio (mol /
As the method for dealumination treatment so that the (mol) is 10 or more, a known method known as an acid treatment method may be used, and for example, the following method is available. The concentration is 0.05 to 95% by weight, preferably 0.1 to
30% by weight, more preferably 0.2 to 10% by weight of an aqueous mineral acid solution, and 0 to 100 ° C., preferably room temperature to 80
0.5 to 100 hours, preferably 1 to 50 at a temperature of ° C.
Acid treatment method of contacting with zeolite for a period of time, acid treatment method of contacting a gaseous acidic substance such as HF, BF ₃ , HCl with zeolite at a temperature of 300 to 700 ° C. for 1 to 100 hours, and the like. You can Other than these treatment methods, a known method known as an acid treatment method may be used. This acid treatment can be carried out by a flow system or a batch system. When the acid treatment is performed to a predetermined stage, the contact with the acid is stopped, and the catalyst is washed with water, dried or calcined. When firing, the temperature should be 500-7
When the temperature is 00 ° C, the activity as a catalyst is excellent. Also, the activity as a catalyst varies depending on the acid used for the acid treatment,
When a hydrochloric acid aqueous solution is used and the concentration is 0.1 to 10% by weight, excellent activity is exhibited. With this acid treatment, the silica / alumina ratio (molar ratio) becomes 10 or more, preferably 15 or more,
Moreover, the ratio is set to be 0.5 or more, preferably 2 or more, and more preferably 4 or more as compared with that before the acid treatment of the present invention. This can be easily adjusted by selecting the acid concentration, time, etc. within the range of the above conditions.

The zeolite to be acid-treated in the present invention may be an ordinary zeolite or a zeolite which has been dealuminated by another method, but in any case, it is finally acid-treated. Need to be dealuminated. Silica / alumina ratio is 1
Better results are often obtained by acid-treating 0 or more or those higher than 0. The acid-treated zeolite catalyst may be used as it is, or may be used after being molded using a commonly used binder such as alumina or clay mineral.

In the present invention, silica /
A zeolite catalyst that has been dealuminated with an alumina ratio (mol / mol) of 10 or more can be used in the following reaction and can be used for maintaining stable activity for a long period in a flow reaction. That is, transalkylation reaction between naphthalene and polyalkylnaphthalene and / or polyalkylbenzenes Transalkylation reaction between alkylnaphthalenes having different number of alkyl groups Transalkylation reaction between naphthalene, alkylnaphthalenes and alkylbenzenes Alkyl Transalkylation reaction between naphthalene and alkylbenzenes Isomerization reaction of dialkylnaphthalene and disproportionation reaction of alkylnaphthalene.

The term "alkylnaphthalene" as used herein means alkylnaphthalene, dialkylnaphthalene, trialkylnaphthalene, tetraalkylnaphthalene, pentaalkylnaphthalene, and hexaalkylnaphthalene including all isomers. “Alkylbenzenes” include alkylbenzenes including all isomers, dialkylbenzenes,
They are trialkylbenzene, tetraalkylbenzene, pentaalkylbenzene and hexaalkylbenzene.
These are used alone or as a mixture.

Further, the polyalkylnaphthalene as the transalkylating agent is a polyalkylnaphthalene of dialkylnaphthalene or higher or a mixture containing the same.
The polyalkylbenzenes are polyalkylbenzenes higher than dialkylbenzene or a mixture containing the same. Preferably, the ratio (molar ratio) of the alkyl group to the benzene ring and the naphthalene ring is 2 or more, preferably 2.5 or more, more preferably 3 or more. To increase the yield of 2,6-dialkylnaphthalene, the alkyl group in the reaction raw material / (naphthalene ring + benzene ring) = 0.5
To 3.5 (mol / mol), more preferably alkyl group /
The compound or mixture is preferably such that (naphthalene ring + benzene ring) = 1.0 to 3.0 (mol / mol).

Naphthalene used as a raw material in the present invention,
Alkylnaphthalene and alkylbenzene have a basic nitrogen content of 50 ppm or less, preferably 10 pp.
m or less, more preferably 5 ppm or less. Further, the alkylnaphthalenes are preferably methylnaphthalenes or ethylnaphthalenes, and the alkylbenzenes are preferably methylbenzenes or ethylbenzenes.
When an alkylnaphthalene or alkylbenzene having an alkyl group having 3 or more carbon atoms is used as a starting material, the liquid phase oxidation step subsequent to the present invention becomes difficult.

The reaction temperature is 100 ° C to 600 ° C, preferably 130 ° C to 550 ° C, more preferably 150 ° C to 5 ° C.
It is 00 ° C. When the reaction temperature is lower than 100 ° C., the reaction rate is slow and not industrial, and when the reaction temperature is higher than 600 ° C., the selectivity of 2,6-dialkylnaphthalene decreases, and dealkylation, decomposition of alkyl group, alkyl group And the coloration of the product occur. Methylation usually requires a reaction temperature about 50-150 ° C. higher than ethylation. In addition, ZSM-5 having a pore diameter of 7.2 Å or less
When a pentasil-type zeolite, L-type zeolite, or mordenite is used in the reaction, it is preferable to set the reaction temperature to 350 ° C. or higher in order to increase the diffusion rate in the pores and accelerate the reaction rate. Reaction pressure is normal pressure to 100 kg /
cm ² , preferably atmospheric pressure to 50 kg / cm ² .

The production method can be carried out in either a flow reaction system or a batch reaction system. A fixed bed flow reaction type is suitable for large-scale production at an industrial level, and a batch reaction type is suitable for small-scale production. When reacted under such conditions, a transalkylation reaction, a disproportionation reaction and / or an isomerization reaction between aromatic rings occur. Therefore, the mixture after the reaction is composed of alkylnaphthalenes such as naphthalene, alkylnaphthalenes, dialkylnaphthalenes, and trialkylnaphthalenes. When polyalkylbenzenes are used as the transalkylating agent, the mixture after the reaction contains alkylbenzenes such as benzene, alkylbenzene, dialkylbenzene and trialkylbenzene, in addition to the alkylnaphthalenes.

The mixture after completion of the reaction of the present invention contains naphthalene, alkylnaphthalene, dialkylnaphthalene, trialkylnaphthalene, tetraalkylnaphthalene, etc. in addition to 2,6-dialkylnaphthalene as described above. , 6-dialkylnaphthalene-containing fraction was collected, and then cooled crystallization, pressure crystallization, adsorption,
By using a known separation method such as Adaks separation,
2,6-dialkylnaphthalene can be separated. When the purity of the separated 2,6-dialkylnaphthalene is not sufficient, the purity can be increased to 100% by recrystallization using a solvent such as methanol, ethanol or isopropanol.

The remaining alkylnaphthalenes and alkylbenzenes from which the 2,6-dialkylnaphthalene has been separated can be recycled again to the reaction and used as a raw material for the 2,6-dialkylnaphthalene.

[0022]

EXAMPLES The present invention will be specifically described below based on examples, but the present invention is not limited to these examples.

Examples 1 to 5 and Comparative Example 1 A 1 liter four-necked flask equipped with a stirrer, a cooler, and a thermometer was added with 500 g of an aqueous hydrochloric acid solution having the concentration shown in Table 1 and H-
100 g of Y-type zeolite was charged, and the mixture was stirred at 40 ° C. for 1 hour and treated with hydrochloric acid. This was filtered, washed with 25 times by weight of water with respect to the zeolite, then dried at 120 ° C. for 10 hours, and calcined at 600 ° C. for 3 hours to obtain a catalyst. The amount of chlorine remaining in the catalyst was about 0.5 to 3 ppm.

Next, 300 equipped with a stirrer and a thermometer
Into a ml autoclave, 81 g of diethylbenzene, 16 g of naphthalene, 27 g of ethylnaphthalene, 37 g of triethylnaphthalene and 48 g of the catalyst treated with hydrochloric acid were charged, and the reaction was carried out at 200 ° C. for 6 hours with stirring. Also, for comparison, the same reaction was carried out for the catalyst not treated with acid. The product obtained by the reaction was analyzed to examine the proportion of diethylnaphthalene (DEN) in the compound having a naphthalene ring. The results are shown in Table 1. It was confirmed that the treatment with hydrochloric acid caused dealumination and that the initial activity of the catalyst was improved.

[0025]

[Table 1]

Examples 6 to 8 A 1 liter four-necked flask equipped with a stirrer, a cooler and a thermometer was charged with 500 g of 1.0 N hydrochloric acid aqueous solution and 100 g of HY zeolite and charged at 40 ° C. for 1 hour. The mixture was stirred and treated with hydrochloric acid. This is filtered, and the amount of zeolite is 25
The catalyst was washed with water in an amount of 1 times the weight of water, dried at 120 ° C. for 10 hours, and calcined at the firing temperature shown in Table 2 for 3 hours to obtain a catalyst. Then, the same reaction as in Example 1 was performed, and the reaction product was examined for the proportion of diethylnaphthalene (DEN) in the compound having a naphthalene ring. The results are shown in Table 2. It was found that the calcination temperature is preferably 750 ° C. or lower from the viewpoint of catalyst activity.

[0027]

[Table 2]

Example 9, Comparative Example 2 The same catalyst as in Example 4 was added to a fixed bed flow reactor at 20 m.
Then, a mixture of triethylbenzene, naphthalene, ethylnaphthalene and triethylnaphthaphthalene (weight ratio 50: 10: 17: 23) was continuously supplied at WHSV = 1 / hr. Triethylbenzene, naphthalene,
Ethylnaphthalene and triethylnaphthalene are each a mixture of isomers close to thermodynamic equilibrium. Using the yield of diethylnaphthalene as a measure of activity, the reaction temperature was raised stepwise to compensate for the decrease in activity. Also, for comparison, the same reaction was performed using the same catalyst as in Comparative Example 1. The results are shown in Table 3.

[0029]

[Table 3]

Comparative Examples 3 to 4 As Comparative Example 3, 20 ml of the same catalyst as in Comparative Example 1 was charged into a fixed bed flow reactor, and a mixture of ethylnaphthalene and triethylnaphthaphthalene (molar ratio 1: 1) was added to WH.
The reaction was carried out by continuously supplying SV = 1 / hr. Ethylnaphthalene and triethylnaphthalene are each a mixture of isomers close to thermodynamic equilibrium. Using the yield of diethylnaphthalene as a measure of activity, the reaction temperature was raised stepwise to compensate for the decrease in activity. Further, as Comparative Example 4, a similar reaction was performed using a HY type zeolite catalyst having a silica / alumina ratio of 6 (molar ratio). The results are shown in Table 4.

[0031]

[Table 4]

[0032]

INDUSTRIAL APPLICABILITY As described above, according to the present invention, an efficient method for producing 2,6-dialkylnaphthalene can be established by a technique for alkylating naphthalene which exhibits stable activity in a fixed bed flow reaction, which is industrially possible. Is meaningful to.

Claims (6)

[Claims] 1. When producing a 2,6-dialkylnaphthalene by transalkylating, isomerizing or disproportionating naphthalene or an alkylnaphthalene in the presence of a zeolite catalyst, a silica / alumina ratio (molar ratio) of 10 is obtained. The method for producing a 2,6-dialkylnaphthalene is characterized in that the zeolite that has been dealuminated by acid treatment so that the ratio is higher than 0.5 and is higher than 0.5 is used as a catalyst. 2. The production of 2,6-dialkylnaphthalene according to claim 1, wherein the transalkylation of naphthalene or alkylnaphthalene is carried out by using polyalkylnaphthalene or polyalkylbenzene as a transalkylating agent. Method. 3. The method for producing a 2,6-dialkylnaphthalene according to claim 2, wherein alkyl is ethyl or methyl. 4. The method for producing a 2,6-dialkylnaphthalene according to claim 1, wherein the zeolite is a faujasite type zeolite. 5. The method for producing a 2,6-dialkylnaphthalene according to claim 1, wherein a mineral acid is used for the acid treatment. 6. The method for producing a 2,6-dialkylnaphthalene according to claim 1, wherein hydrochloric acid is used for the acid treatment.