JPH05221887A - Production of 2,6-dialkylnaphthalene - Google Patents

Abstract

PURPOSE:To obtain a method for producing a 2,6-dialkylnaphthalene with good efficiency according to a selective alkylating technique using a catalyst other than a Lewis acid such as AlCl3 and exhibiting stable activity for a lone period in fixed bed flow reaction. CONSTITUTION:The objective method for producing a 2,6-dialkylnaphthalene is to make naphthalenes as one kind of raw material selected from naphthalene and 2-alkylnaphthalenes react with polyalkylbenzenes in the presence of a solid acid catalyst absorbing 0.5-40wt.% moisture at 50-400 deg.C reactional temperature.

Description

Detailed Description of the Invention

[0001]

FIELD OF THE INVENTION The present invention relates to a method for producing 2,6-dialkylnaphthalene which is 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 superior to polyethylene terephthalate in heat resistance, breaking strength, and the like, and is attracting attention as a material for films, food packaging materials, and the like.

One of the industrially advantageous methods for producing 2,6-naphthalenedicarboxylic acid is liquid phase oxidation of 2,6-diisopropylnaphthalene, but it is difficult to oxidize isopropyl groups to carboxyl groups. However, it was not always satisfactory industrially. Compared to this method, 2,6-dimethylnaphthalene, 2-methyl-
The method of liquid phase oxidation of 6-ethylnaphthalene and 2,6-diethylnaphthalene has a high yield in the liquid phase oxidation step,
It is expected as an inexpensive method for producing 2,6-naphthalenedicarboxylic acid. Therefore, it has been desired to establish an efficient and inexpensive method for producing 2,6-dimethylnaphthalene, 2-methyl-6-ethylnaphthalene and 2,6-diethylnaphthalene. However, a naphthalene or methylnaphthalene and a methylating agent such as methanol or methyl halide or an ethylating agent such as ethylene or ethyl halide is used as AlCl ₃
In the method of reacting in the presence of a Lewis acid catalyst such as
The selectivity of 6-dimethylnaphthalene, 2-methyl-6-ethylnaphthalene or 2,6-diethylnaphthalene is low, and in addition, the pitch formation by polymerization of the naphthalene ring is severe, which is a problem for industrial application.

A method for producing ethylnaphthalene by reacting naphthalene with ethylbenzene is described in US Pat.
P4,873,386 and Bull. Che
m. Soc. Jpn. , 48 , 3306 to 3308 (1
975), any of them uses a Lewis acid such as AlCl ₃ or AlCl ₃ which is soluble in the reaction system as a catalyst, and therefore requires a water washing and neutralization step for removing the catalyst after completion of the reaction. There are some drawbacks such as a large amount of acidic waste water containing AlCl ₃ being emitted, it is difficult to continue the reaction, and a material having strong acid resistance is required for the reaction apparatus. Also, when a Lewis acid such as AlCl ₃ is used as a catalyst, the pitch formation due to the polymerization of the naphthalene ring is severe,
It was a problem.

Japanese Unexamined Patent Publication No. 1-299,237 discloses 2
-A method for transisopropylating methylnaphthalene with a zirconia catalyst supported on sulfuric acid is described, but 2,7
The production ratio of 2,6-dialkylnaphthalene to -dialkylnaphthalene is 1.12, which is not necessarily a selective production method of 2,6-dialkylnaphthalene.

Japanese Unexamined Patent Publication (Kokai) No. 64-68,329 describes an aromatic transethylation reaction using a solid acid catalyst, but there is nothing to teach selective ethyl of naphthalene.

US Pat. No. 5,001,295 describes
The methylation reaction of 2-alkylnaphthalene with methanol using a zeolite catalyst is described, but the conversion is low and it is not industrial.

JP-A-63-14,737 discloses Y
It describes a method for producing methylnaphthalenes by reacting naphthalene with methylbenzenes using a solid acid catalyst such as type zeolite. However, JP-A-63
If Y-type zeolite calcined at 500 ° C. as described in the examples of JP-A-14,737 is used for the reaction, it is difficult to obtain stable activity for a long period of time.

[0009]

SUMMARY OF THE INVENTION The present invention was devised in view of such circumstances, and its purpose is to:
An object of the present invention is to provide an efficient method for producing 2,6-dialkylnaphthalene by using a catalyst other than a Lewis acid such as AlCl ₃ and using a selective alkylation technique which shows stable activity for a long time in a fixed bed flow reaction.

As a result of intensive studies to establish the above-mentioned method, the present inventors have found that a catalyst has an acid point of pore diameter of 7.2 Å or more and NH ₃ differential heat of adsorption of 85 kJ / mol or more. It has 0.1mol / kg or more and 0.5 ~
The present invention has been completed by finding that 2,6-dialkylnaphthalene can be efficiently produced with high selectivity by using polyalkylbenzene as an alkylating agent using a solid acid having a moisture content of 40% by weight.

That is, according to the present invention, naphthalene and / or alkylnaphthalene and polyalkylbenzene are used, and the pore diameter is 7.2 Å or more and the NH ₃ differential adsorption heat is 85 k.
Having an acid point of J / mol or more of 0.1 mol / kg or more,
A method for producing 2,6-dialkylnaphthalene, which comprises reacting at a reaction temperature of 50 to 400 ° C. in the presence of a solid acid catalyst having moisture absorbed by 0.5 to 40% by weight.

The manufacturing method of the present invention will be described in detail below. The type of solid acid catalyst used in the present invention, silica alumina, zeolite, composite metal oxides, solid phosphoric acid, heteropolyacid, among the catalysts known as normal solid acid catalyst such as ion exchange resin, the pore size Is 7.2
Å or more, NH ₃ differential heat of adsorption is 85 kJ / mol
It is a solid acid catalyst having the above acid points of 0.1 mol / kg or more. With respect to the amount of acid, it is more preferable that the NH ₃ differential adsorption heat has an acid point of 0.1 mol / kg or more with 85 kJ / mol or more, and the NH ₃ differential adsorption heat is 130 kJ / mol.
It is a solid acid catalyst having the above acid points of 0.01 mol / kg or more. The definition of the NH ₃ differential heat of adsorption is defined in the literature by Bu.
ll. Chem. Soc. Jpn. , 48 , 3576
(1975). With a solid acid catalyst having a pore size of 7.2 Å or less, there is not enough reaction field for the transethylation reaction to occur between the naphthalene ring and the benzene ring, so an extremely low conversion rate can be obtained, and therefore it is industrially difficult. Is almost impossible to employ. Also, the NH ₃ differential heat of adsorption is 85 jo
With a solid acid catalyst having an acid point of ul / mol or more of only 0.1 mol / kg or less, it is not possible to increase the yield while maintaining high selectivity of 2-alkyl-6-ethylnaphthalene. Hiring is difficult. Examples of solid acid catalysts that satisfy these conditions and are industrially readily available include silica alumina, zeolite, and ion exchange resins. As zeolite, faujasite, Y
-Type zeolite, X-type zeolite, or those obtained by chemically treating these with ion exchange treatment, dealumination treatment, fluorination treatment, steam treatment, or the like. Zeolites such as L-type zeolite, mordenite, and ZSM-5 having a pore size of 7.2 Å or less can obtain an extremely low conversion rate, probably because the reaction occurs only on the surface of the zeolite particles. Silica-alumina generally has a smaller amount of acid than zeolite, but since it is amorphous, it does not hinder the reaction due to the small pore size of L-type zeolite, mordenite, etc., and is preferred as the catalyst of the present invention. Silica-alumina can also be used for the reaction after chemical treatment such as ion exchange treatment, dealumination treatment, fluorination treatment, and steam treatment. As the ion exchange resin, the one having a higher heat resistant temperature is preferable because a wide range of reaction conditions can be selected. Examples of such resins include ion exchange resins sold by DuPont as perfluoro-type Nafion. The acid amount of these solid acid catalysts is NH
₃ Acids with differential heat of adsorption of 85 kJ / mol or more 3 mol
Those having an amount of not more than / kg are preferable. The number of acid points is 3 mol /
If it is more than kg, the deposition rate of carbonaceous matter becomes faster and the catalyst life becomes shorter. Incidentally, among the solid acid catalysts, the metal oxide such as zeolite having lost the activity can be easily regenerated by a method of burning carbon oxide at about 500 ° C. to remove carbonaceous matter.

The solid acid catalyst as described above is used for the reaction after absorbing moisture. The amount of moisture to be absorbed is an amount corresponding to 0.5 to 40% by weight, preferably 0.5 to 20% by weight, based on the catalyst from which the physically attached water is completely removed. A solid acid catalyst having a water absorption capacity of 40% by weight or more may be allowed to absorb moisture up to the upper limit of its moisture absorption capacity.

There are various methods for absorbing moisture, for example, method: leaving in the atmosphere, method: contacting with steam, method: mixing water into the reaction raw material, and the like. Of these, two or more methods may be used at the same time.

When using the method, it is important to take care not to carry out under an atmosphere of an organic substance which is adsorbed on the solid acid catalyst. Further, when the method is used, it is necessary to treat at a temperature that does not change the structure of the solid acid catalyst. For example, it is necessary to treat the ion-exchange resin at 100 ° C. or lower and the zeolite catalyst at 300 ° C. or lower.
However, this is not the case when the purpose is to carry out dealumination treatment and moisture absorption treatment of the zeolite catalyst at the same time. Further, when the method is used in a flow reaction mode, it is suitable to prepare the reaction raw material so that the water content is 30 ppm to saturated concentration, preferably 100 ppm to saturated concentration, and supply it to the reaction system.

Of the solid acid catalysts used in the present invention, when it is necessary to mold the solid acid catalyst at the time of use, it is molded using a commonly used binder such as alumina or clay mineral, and then subjected to a moisture absorption treatment for reaction. Can be used.

The reaction raw material used in the present invention is naphthalene and / or alkylnaphthalene. When alkylnaphthalene or a material mainly containing alkylnaphthalene is used as a raw material, the selectivity and the yield of 2,6-dialkylnaphthalene are increased. 2- as alkylnaphthalene
Alkylnaphthalene or 2-alkylnaphthalene and 1
Although it is a mixture of -alkylnaphthalene, it is advantageous that the content of 2-alkylnaphthalene is large because the selectivity and yield of 2,6-dialkylnaphthalene are high. The raw material naphthalene or alkylnaphthalene may be used alone or in combination. Naphthalene and alkylnaphthalene used as raw materials have a basic nitrogen content of 50.
ppm or less, preferably 20 ppm or less. Further, as the “alkylnaphthalene” referred to herein, methylnaphthalene or ethylnaphthalene is preferable. Carbon number 3
When naphthalene having an alkyl group as described above is used as a starting material, the liquid phase oxidation step subsequent to the present invention becomes difficult, which is not preferable. For the same reason, polymethylbenzene or polyethylbenzene is also preferable as the polyalkylbenzene as an alkylating agent described later. In order to avoid mixing different alkyl groups in the reaction system, when 2-methylnaphthalene is used as the starting material, polymethylbenzene is used as the polyalkylbenzene as the alkylating agent and 2-ethylnaphthalene is used as the starting material. When used as the raw material, polyethylbenzene is preferable as the polyalkylbenzene as the alkylating agent.

The polyalkylbenzene as the alkylating agent is preferably polymethylbenzene or polyethylbenzene for facilitating the liquid phase oxidation step subsequent to the present invention. Polymethylbenzene used as a methylating agent is
o-xylene, m-xylene, p-xylene, 1,2,
3-trimethylbenzene, 1,2,4-trimethylbenzene, 1,3,5-trimethylbenzene, 1,2,3
One or a mixture of two or more selected from 4-tetramethylbenzene, 1,2,3,5-tetramethylbenzene, 1,2,4,5-tetramethylbenzene, pentamethylbenzene and hexamethylbenzene. Yes, preferably methyl group / benzene ring = 2 (mol / mol) or more, more preferably 3 (mol / mol) or more, further preferably 3.5.
(Mole / mole) or more of the compound or mixture. If this ratio is small, the reaction proceeds slowly. Preferred is trimethylbenzene or tetramethylbenzene or a mixture mainly containing them. As such polymethylbenzene, commercially available products such as xylene and trimethylbenzene can be obtained, and polymethylbenzene containing tetramethylbenzene as a main component by methylating these with methanol, methyl halide or the like. Can be obtained. Polyethylbenzene used as an ethylating agent is 1,2-diethylbenzene, 1,3-diethylbenzene, 1,4-diethylbenzene, 1,2,3-triethylbenzene, 1,2,4-triethylbenzene, 1,2.
1 selected from 3,5-triethylbenzene, 1,2,3,4-tetraethylbenzene, 1,2,3,5-tetraethylbenzene, 1,2,4,5-tetraethylbenzene, pentaethylbenzene and hexaethylbenzene Or a mixture of two or more, preferably ethyl group / benzene ring = 2 (mol / mol) or more, more preferably 3
(Mole / mole) or more, more preferably 3.5 (mole / mole) or more. If this ratio is small, the reaction proceeds slowly. Preferred is triethylbenzene or tetraethylbenzene or a mixture mainly of them. As such polyethylbenzene, it is possible to use polyethylbenzene mainly containing diethylbenzene or triethylbenzene which is by-produced as a high-boiling point fraction in the production of ethylbenzene, and these are treated with ethanol, ethylene, etc. It is possible to use polyethylbenzene mainly containing tetraethylbenzene obtained by ethylation.

The reaction temperature is 50 to 400 ° C, preferably 50 to 300 ° C, more preferably 50 to 280 ° C. When the reaction temperature is lower than the melting point of the reaction raw material, a solvent such as decalin or n-paraffin that does not participate in the reaction can be used. When the reaction temperature is lower than 50 ° C., the reaction rate is slow and not industrial, and when the reaction temperature is higher than 400 ° C., the selectivity of 2,6-dialkylnaphthalene decreases, and dealkylation, decomposition of alkyl group, alkyl group And the coloring of the product occur. Generally, the lower the reaction temperature is, the better the selectivity of 2,6-dialkylnaphthalene is. When the higher reaction temperature is selected, the shorter the reaction time, the higher the selectivity of 2,6-dialkylnaphthalene can be obtained.

The reaction pressure is atmospheric pressure to 100 kg / cm ^2, preferably atmospheric pressure to 50 kg / cm ^2. Considering the life of the catalyst, it is appropriate to select the reaction pressure so that the reaction raw material and the reaction product become liquid in the reactor.

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 the reaction is carried out under such conditions, a transalkylation reaction occurs, alkylating naphthalene and / or alkylnaphthalene and dealkylating alkylbenzene. Therefore, the mixture after the reaction is composed of alkylnaphthalenes such as naphthalene, alkylnaphthalene, dialkylnaphthalene and trialkylnaphthalene and alkylbenzenes such as benzene, alkylbenzene and dialkylbenzene.

The mixture after completion of the reaction of the present invention contains alkylbenzenes, naphthalene, alkylnaphthalene, dialkylnaphthalene, trialkylnaphthalene, tetraalkylnaphthalene, etc. in addition to 2,6-dialkylnaphthalene as described above. The 2,6-dialkylnaphthalene can be separated by collecting a fraction containing 2,6-dialkylnaphthalene by distillation and then using a separation method such as cooling crystallization, pressure crystallization, adsorption, and adduct separation. 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.

[0024]

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

Examples 1 and 2 A fixed bed flow reactor was filled with 20 cc of Y-type zeolite or Y-type zeolite as a catalyst, and a mixture of 2-ethylnaphthalene and tetraethylbenzene isomers was used for WHSV.
It was continuously fed at = 1 h ^-1 . 2-ethylnaphthalene /
Tetraethylbenzenes = 3 mol / mol. The Y-type zeolite or the Y-type zeolite was air-calcined at 300 ° C. for 18 hours and then left in the air to absorb about 7% of the dry weight. The reaction raw material had a water content of 350 ppm. The results are shown in Table 1. In addition, SiO ₂ / Al ₂ O ₃ (mol / mol) of the skeleton of Y-type zeolite is Y
The type zeolite is 6, and the type Y zeolite used for the catalyst is 100. The type Y zeolite is obtained by treating the type Y zeolite with HCl to increase SiO ₂ / Al ₂ O ₃ . Further, the Y-type zeolite has 1.3 mol / kg, the Y-type zeolite has 0.4 mol / kg, and the silica-alumina has 0.2 mol / kg, respectively, with acid points having an NH ₃ differential adsorption heat of 85 kJ / mol or more.

Comparative Examples 1 and 2 The same reactions as in Examples 1 and 2 were carried out except that the catalyst was not allowed to absorb moisture after air calcination and the reaction raw materials were sufficiently dehydrated. The results are shown in Table 1.

[0027]

[Table 1]

In Table 1 above, comparing Example 1 with Comparative Example 1 and comparing Example 2 with Comparative Example 2, the reaction temperature shifts to the temperature lowering side by absorbing the catalyst. It can be seen that the conversion rate lowering rate became slower and the catalyst life was extended.

[0029]

As described above, according to the present invention, 2,6-
Diethylnaphthalene can be produced efficiently and is industrially significant.

Claims (8)

[Claims] 1. Naphthalenes and polyalkylbenzenes as raw materials of at least one selected from naphthalene and 2-alkylnaphthalene and water content of 0.5 to 40.
In the presence of a solid acid catalyst having a moisture content of 50% by weight, a reaction temperature of 50 to
A method for producing 2,6-dialkylnaphthalene, which comprises reacting at 400 ° C. 2. The method for producing 2,6-dialkylnaphthalene according to claim 1, wherein the polyalkylbenzenes are polyethylbenzenes. 3. The method for producing 2,6-dialkylnaphthalene according to claim 1, wherein the polyalkylbenzenes have an alkyl group / benzene ring (molar ratio) of 3 or more. 4. A solid acid catalyst having moisture absorbed by 0.5 to 40% by weight has a pore diameter of 7.2 Å or more and an NH ₃ differential heat of adsorption of 0.1 mol of an acid point of 85 kJ / mol or more.
2. The metal oxide having a metal oxide content of at least 1 kg / kg.
-Method for producing dialkylnaphthalene. 5. A solid acid catalyst having moisture absorbed by 0.5 to 40% by weight has a pore size of 7.2 Å or more and an NH ₃ differential heat of adsorption of 0.01 m at an acid point of 130 kJ / mol or more.
A solid acid having an ol / kg or more of 2, 6 according to claim 1.
-Method for producing dialkylnaphthalene. 6. The method according to claim 2, wherein the solid acid catalyst having moisture absorbed by 0.5 to 40% by weight is Y-type zeolite or silica alumina having moisture absorbed by 0.5 to 40% by weight. -Method for producing dialkylnaphthalene. 7. At least one naphthalene selected from naphthalene and alkylnaphthalene and one or more selected from the group consisting of dialkylbenzene, trialkylbenzene, tetraalkylbenzene, pentaalkylbenzene and hexaalkylbenzene. With polyalkylbenzenes, the pore size is 7.2 Å or more, the NH ₃ differential heat of adsorption is 0.1 mol / kg or more with an acid point of 85 kJ / mol or more, and the water content is 0.5 to
Reaction temperature 5 in the presence of a solid acid catalyst that has absorbed 40% by weight of moisture.
A method for producing 2,6-dialkylnaphthalene, which comprises reacting at 0 to 400 ° C. 8. At least one naphthalene selected from naphthalene and alkylnaphthalene and one or more selected from the group consisting of dialkylbenzene, trialkylbenzene, tetraalkylbenzene, pentaalkylbenzene and hexaalkylbenzene. With polyalkylbenzenes, 0.01 mol / kg or more of acid points having a pore size of 7.2 Å or more, NH ₃ differential heat of adsorption of 130 kJ / mol or more, and water content of 0.
2,6, wherein the reaction is carried out at a reaction temperature of 50 to 400 ° C. in the presence of a solid acid catalyst which has absorbed 5 to 40% by weight of moisture.
-Method for producing dialkylnaphthalene.