JPH06145077A - Production of 2,6-diethylnaphthalene - Google Patents

Abstract

PURPOSE:To provide a process for producing 2,6-diethylnaphthalene in relatively high naphthalene conversion and relatively high 2,6-diethylnaphthalene yield by using polyethylbenzene in combination with ethylene as an ethylation agent. CONSTITUTION:2,6-Diethylnaphthalene is produced by ethylating naphthalene or ethylnaphthalene with polyethylbenzene and ethylene. The reaction is carried out at 150-300 deg.C in the presence of a solid acid catalyst such as zeolite at a polyethylbenzene/naphthalene weight ratio of 5-50 and a polyethylbenzene/ ethylene molar ratio of 5-50. The catalyst life can be prolonged to >=1 month. The polyethylbenzene can be reused as it is.

Description

Detailed Description of the Invention

[0001]

FIELD OF THE INVENTION The present invention relates to a method for producing 2,6-diethylnaphthalene 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 such as polyester and a dye intermediate. As one of industrially advantageous methods for producing 2,6-naphthalenedicarboxylic acid, there is a method of liquid-phase oxidation of 2,6-diisopropylnaphthalene, but it is difficult to oxidize an isopropyl group to a carboxyl group, It was not always satisfactory industrially. Compared with this method, the method of liquid-phase oxidation of ethyl 2,6-diethylnaphthalene has a high yield in the liquid-phase oxidation step and is expected as an inexpensive method for producing 2,6-naphthalenedicarboxylic acid. . Although dimethylnaphthalene is advantageous in terms of yield in the liquid-phase oxidation step, it has a problem that it is difficult to synthesize. In this sense, it would be extremely advantageous if 2,6-diethylnaphthalene, which has a high yield in the oxidation step next to the methyl group, is easily available as a raw material, and is easy to synthesize, can be obtained efficiently. .

However, in the usual method in which naphthalene such as naphthalene or ethylnaphthalene is reacted with an ethylating agent such as ethylene or ethylhalide in the presence of an acid catalyst such as AlCl ₃ , 2,6-diethylnaphthalene is selected. The rate is low, and in addition, the pitch formation due to the polymerization of naphthalene is severe, which is a problem for industrial application. Further, a method for producing ethylnaphthalene by reacting naphthalene with ethylbenzene is described in _{USP 4,873,386 and the} like, but both are AlCl ₃ or FeCl ₃
Since a Lewis acid that dissolves in the reaction system is used as a catalyst, it is necessary to wash with water to remove the catalyst and neutralize after the completion of the reaction. A large amount of acidic wastewater containing AlCl ₃ appears, and the reaction continues. However, there are drawbacks such as that it is difficult to make it into a reactor, and that the reactor requires a material having strong acid resistance. Also, AlC
When using a Lewis acid of l ₃ etc. as a catalyst, severe pitch by polymerization of naphthalenes, which is a problem. In order to solve this, International Publication WO92 / 02473 proposes a method for producing 2,6-diethylnaphthalene using a solid acid catalyst. This method is a method of trans-ethylating naphthalene with polyethylbenzene, and has many advantages such as excellent selectivity of 2,6-diethylnaphthalene, but it is not suitable for production of raw material polyethylbenzene and life of solid acid catalyst. It was recognized that there is room for improvement in this respect. Japanese Unexamined Patent Publication No. 63-14737 discloses a method for producing a dialkylnaphthalene by simultaneously contacting naphthalene, polyalkylbenzene and olefin with a solid acid catalyst. Specifically, methylnaphthalene and polymethylnaphthalene are disclosed. Only the reaction with benzene and methanol is disclosed, and there is no teaching how to produce diethylnaphthalene.

[0004]

DISCLOSURE OF THE INVENTION The object of the present invention is to produce 2,6-diethylnaphthalene selectively and efficiently by prolonging the life of the solid acid catalyst in the ethylation of naphthalene compounds using the solid acid catalyst. It is to provide a manufacturing method.

[0005]

Means for Solving the Problems The inventors of the present invention have conducted extensive studies in order to establish the above method. As a result, a solid acid catalyst was used as a catalyst, and both polyethylbenzene and ethylene were identified as alkylating agents. It was found that 2,6-diethylnaphthalene can be efficiently produced with a high selectivity by using the above-mentioned ratio, and the present invention has been completed. That is,
In the present invention, when naphthalene is reacted with polyethylbenzene and ethylene to produce 2,6-diethylnaphthalene, the weight ratio of polyethylbenzene / naphthalene is 5 to 50, and the molar ratio of polyethylbenzene / ethylene is 5 to 50. In the presence of a solid acid catalyst at a reaction temperature of 15
It is a method for producing 2,6-diethylnaphthalene which is reacted at 0 ° C to 300 ° C.

The type of solid acid catalyst used in the present invention is a catalyst generally known as a solid acid catalyst such as silica-alumina, zeolite, complex metal oxide, solid phosphoric acid, heteropolyacid, ion exchange resin and the like. However, it is preferably a zeolite-based solid acid catalyst having a pore size of 7.2 Å or more.
In the case of a solid acid catalyst having a pore size of 7.2 Å or less, there is not enough reaction field for the transethylation reaction between the naphthalene ring and the benzene ring, so the conversion rate becomes low.

Examples of solid acid catalysts which satisfy these conditions and which are industrially readily available include silica alumina, zeolite and ion exchange resins. As the zeolite, faujasite-type zeolite, particularly Y-type zeolite, X-type zeolite, or those obtained by chemical treatment such as ion exchange treatment, dealumination treatment, fluorination treatment, and steam treatment are preferable. 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. As such a resin, a perfluorosulfonic acid type cation exchange resin, for example, Nafion (trade name) manufactured by DuPont can be exemplified.
It should be noted that, among the solid acid catalysts, the metal oxide such as zeolite having lost its activity can be easily regenerated by a method of removing carbonaceous matter by firing at about 500 ° C. with air diluted with nitrogen.

Examples of naphthalene used as a raw material in the present invention include naphthalene and ethylnaphthalene. Although naphthalene is inexpensive and advantageous as a raw material, it is also advantageous to circulate ethylnaphthalene produced as a reaction by-product in the reaction system. Therefore, when circulating ethylnaphthalene, both are included as naphthalene.

Polyethylbenzene includes 1,2-diethylbenzene, 1,3-diethylbenzene, 1,4-diethylbenzene,
1,2,3-triethylbenzene, 1,2,4-triethylbenzene, 1,3,5-triethylbenzene, 1,2,3,4-tetraethylbenzene, 1,2,3,5-tetraethylbenzene, 1 One or a mixture of two or more selected from 2,2,4,5-tetraethylbenzene, pentaethylbenzene and hexaethylbenzene, preferably ethyl group / benzene ring = 1.2 to 4
(Mol / mol), more preferably 1.5 to 3 (mol / mol). If this ratio is small, the reaction proceeds slowly. A mixture mainly containing diethylbenzene is preferable. Such polyethylbenzene can be obtained as polyethylbenzene from a high-boiling fraction produced as a by-product during the production of ethylbenzene, and if necessary, further reacted with ethylene to increase the ethyl group / benzene ring ratio. This polyethylbenzene acts not only as an ethylating agent but also as an ethylene absorbent and a reaction solvent.

Ethylene used with polyethylbenzene also acts as an ethylating agent for naphthalene,
It is also considered to act as an ethylating agent for ethylating polyethylbenzene having reduced ethyl groups. When the reaction of naphthalene and ethylene is carried out directly, the absorption of ethylene does not occur, the reaction does not easily occur, and the catalyst life is extremely short.

The amount of polyethylbenzene and ethylene used is such that the weight ratio of polyethylbenzene / naphthalene is 5 to 5.
The amount is 0, preferably 10 to 40, and the molar ratio of polyethylbenzene / ethylene is 5 to 50, preferably 10 to 40. If the weight ratio of polyethylbenzene / naphthalene is small, the life of the catalyst is shortened, and the absorption rate of ethylene is reduced, so that the reaction rate is reduced. Further, if this weight ratio is too large, the productivity is reduced. If the molar ratio of polyethylbenzene / ethylene is small, the catalyst life will be shortened, and by-products of impurities will increase. If it is too large, the productivity will decrease.

The reaction temperature is 150 ° C to 350 ° C, preferably 180 ° C to 300 ° C. If the reaction temperature is too high, the catalyst life will be shortened, as well as deethylation, decomposition of ethyl groups,
Polymerization of ethyl groups, coloring of products, etc. occur. Generally, the lower the reaction temperature, the better the selectivity of 2,6-diethylnaphthalene. The reaction pressure is 5 to 100 kg / cm ² , preferably 10 to 50 kg / cm ² . The higher the reaction pressure, the faster the absorption rate of ethylene.

The reaction method may be either a flow reaction type or a batch reaction type. 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. The naphthalene and polyethylbenzene may be mixed in advance and then charged into the reactor or separately. Further, ethylene may be charged into the reactor from one place or may be charged in multiple stages. Further, the reactor may be divided into two or more.

When the reaction is carried out under such conditions, a transethylation reaction occurs, the naphthalenes are ethylated and the polyethylbenzene is deethylated. At the same time, ethylation of naphthalene and polyethylbenzene with ethylene occurs. Therefore, the mixture after the reaction is composed of naphthalene such as naphthalene, ethylnaphthalene, diethylnaphthalene and triethylnaphthalene and benzene such as benzene, ethylbenzene and diethylbenzene.

The reaction time or contact time may be 10 minutes to 20 hours, preferably 20 minutes to 10 hours, depending on other conditions. Then, the conversion rate of naphthalene as a raw material can be controlled by selecting conditions such as reaction temperature and reaction time. Preferably, the conversion rate of naphthalene is 80% or more, and the ratio of 2,6-body / 2,7-body in 2,6-diethylnaphthalene is 1.0 or more. Further, the conversion rate of ethylene is preferably 90% or more.

The mixture after the reaction of the present invention contains ethylbenzenes, various naphthalenes and the like in addition to 2,6-diethylnaphthalene as described above. First, a fraction containing 2,6-diethylnaphthalene is distilled. Is separated and then 2,6-diethylnaphthalene is separated by using a separation method such as cooling crystallization, pressure crystallization, adsorption, and adduct separation. When the purity of the separated 2,6-diethylnaphthalene is not sufficient, 100% is obtained by recrystallization using a solvent such as methanol, ethanol, isopropanol and the like.
The purity can be increased up to. The remaining naphthalene, ethylnaphthalene, diethylnaphthalene, triethylnaphthalene and the like after separating 2,6-diethylnaphthalene can be recycled to the reactor and used again as a raw material for 2,6-diethylnaphthalene. Similarly, polyethylbenzene can be recycled.

[0017]

【Example】

Example 1 A raw material oil in which naphthalene or naphthalene compounds were dissolved in polyethylbenzene mainly containing diethylbenzene and ethylene were continuously charged into a reactor to carry out a reaction. As the reactor, two pipe-type reaction groups were used, the same amount of the modified Y-type zeolite was filled in each, and the first reactor and the second reactor were connected in series in this order to carry out the reaction. Ethylene was charged from the inlet of each reactor, and the reaction pressure was about 38 atm. The product oil flowing out from each reactor was subjected to gas chromatographic analysis to determine the conversion rate of naphthalene and the yield of 2,6-diethylnaphthalene. The conditions and results are shown in Table 1, and the composition of the raw material and the product oil discharged from the reactor are shown in Table 2. The ethylene conversion rate is about 10
It was 0%. (Hereafter, this page margin)

[0018]

[Table 1]

[0019]

[Table 2]

In Table 1, the reactor is the first reactor, and is the first reactor. A molar ratio of / 0 indicates an example in which ethylene was not blown in, and is a comparative example. PEB / E represents polyethylbenzene / ethylene. WHSV is a value calculated from the catalyst amount of the first reactor for the first reactor and calculated from the catalyst amount of all the reactors for the second reactor. Conversion = (naphthalene in raw material-naphthalene in product) / naphthalene in raw material x 100 Yield = (2,6-DEN in product-2.6 in raw material
-DEN) / (naphthalene in raw material-naphthalene in product) x (128/184) x 100

In Table 2, the numbers correspond to those in Table 1, and the numbers 1-0, 2-0, 3-0 and 4-0 indicate the compositions of the respective raw materials. The symbols are as follows. EB
Ethylbenzene, DEB Diethylbenzene, TEB
Triethylbenzene, TPEB tetra and pentaethylbenzene, N naphthalene, EN ethylnaphthalene, DEN diethylnaphthalene, TEN triethylnaphthalene, 2,6-ratio The ratio of 2,6-DEN in DEN.

[0022]

According to the production method of the present invention, a relatively high naphthalene conversion rate and a relatively high yield of 2,6-diethylnaphthalene can be obtained, and the catalyst life is as long as one month or more.
Further, polyethylbenzene can be reused as it is.

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[Procedure amendment]

[Submission date] July 1, 1993

[Procedure Amendment 1]

[Document name to be amended] Statement

[Correction target item name] 0010

[Correction method] Change

[Correction content]

Ethylene used with polyethylbenzene also acts as an ethylating agent for naphthalene,
It is also considered to act as an ethylating agent for ethylating polyethylbenzene having reduced ethyl groups. Direct reaction between naphthalene and ethylene makes it difficult for the reaction to occur.
Not only the side reaction of ethylene and naphthalene
A polymerization reaction occurs and the catalyst life becomes extremely short .

[Procedure Amendment 2]

[Document name to be amended] Statement

[Name of item to be corrected] 0015

[Correction method] Change

[Correction content]

The reaction time or contact time may be 10 minutes to 20 hours, preferably 20 minutes to 10 hours, depending on other conditions. Then, the conversion rate of naphthalene as a raw material can be controlled by selecting conditions such as reaction temperature and reaction time. Preferably, the conversion rate of naphthalene is 70 % or more, and the ratio of 2,6-body / 2,7-body in 2,6-diethylnaphthalene is 1.0 or more. Further, the conversion rate of ethylene is preferably 80 % or more.

[Procedure 3]

[Document name to be amended] Statement

[Correction target item name] 0016

[Correction method] Change

[Correction content]

The mixture after the reaction of the present invention contains ethylbenzenes, various naphthalenes and the like in addition to 2,6-diethylnaphthalene as described above. First, a fraction containing 2,6-diethylnaphthalene is distilled. Is separated and then 2,6-diethylnaphthalene is separated by using a separation method such as cooling crystallization, pressure crystallization, adsorption, and adduct separation. When the purity of the separated 2,6-diethylnaphthalene is not sufficient, it is recrystallized using a solvent such as methanol, ethanol or isopropanol to obtain 98% or more.
The purity can be increased up to the top . The remaining naphthalene, ethylnaphthalene, diethylnaphthalene, triethylnaphthalene and the like after separating 2,6-diethylnaphthalene can be recycled to the reactor and used again as a raw material for 2,6-diethylnaphthalene. Similarly, polyethylbenzene can be recycled.

[Procedure amendment 4]

[Document name to be amended] Statement

[Correction target item name] 0020

[Correction method] Change

[Correction content]

In Table 1, the reactor means the first reactor and the means the second reactor . A molar ratio of / 0 indicates an example in which ethylene was not blown in, and is a comparative example. PEB / E represents polyethylbenzene / ethylene. WHSV is a value calculated from the catalyst amount of the first reactor for the first reactor and calculated from the catalyst amount of all the reactors for the second reactor. Conversion = (naphthalene in raw material-naphthalene in product) / naphthalene in raw material x 100 Yield = (2,6-DEN in product-2.6 in raw material
-DEN) / (naphthalene in raw material-naphthalene in product) x (128/184) x 100

Claims (2)

[Claims] 1. In producing 2,6-diethylnaphthalene by reacting naphthalene and / or ethylnaphthalene with polyethylbenzene and ethylene, a polyethylbenzene / naphthalene weight ratio of 5 to 50 is used. The ethylbenzene / ethylene molar ratio is 5 to 50, and the reaction temperature is 150 in the presence of a solid acid catalyst.
A method for producing 2,6-diethylnaphthalene, which comprises reacting at a temperature of 300 to 300 ° C. 2. The method for producing 2,6-diethylnaphthalene according to claim 1, wherein the solid acid catalyst is zeolite having a pore size of 7.2Å or more.