JPS62240632A - Method for separating dimethylnaphthalene isomer - Google Patents

Abstract

PURPOSE:To separate specific isomers efficiently and in high purity, by bringing a dimethylnaphthalene isomer mixture into contact with X type or Y type zeolite subjected to ion exchange with a metallic ion an alkaline(earth)metal and rare earth metal. CONSTITUTION:Dimethylnaphthalene isomers are brought into contact with X type or Y type zeolite subjected to ion exchange with a metallic ion selected from alkaline(earth)metal and rare earth metal as an adsorbent at room temperature - 150 deg.C to separate especially 1,4-dimethylnaphthalene. The ion exchange of the zeolite is carried out by pretreating the X type of Y type zeolite by water washing and calcining, etc., immersing the zeolite in an aqueous solution of a compound containing the metallic ion, heating, repeating these operations by the use of new aqueous solutions several times, washing the zeolite with distilled water, drying and calcining.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method for efficiently separating a specific isomer from a mixture of dimethylnaphthalene isomers.
, 4-dimethylnaphthalene using a specific zeolite adsorbent.

Technical background of the invention and its problems Dimethylnaphthalene (hereinafter sometimes abbreviated as DMN) has 10 types of isomers as shown below, and the weight of these 10 isomers is Depending on the position of the methyl group as a substituent, it is classified into three types: αα type, αβ type, and ββ type.

CCCC OO 1,8-DHN 1.5-DHN 1.4-D
HN1.2-DIN 1.6-DH1,7-DI
N 1.3-DHN As described above, there are 10 types of dimethylnaphthalene isomers, and among these, 1,4-dimethylnaphthalene is a particularly industrially useful compound.

This is because, when 1,4-dimethylnaphthalene is oxidized, it becomes naphthalene-1,4-dicarboxylic acid, which can be used as a raw material compound for producing polyesters, polyamides, and the like.

By the way, dimethylnaphthalene is usually obtained as a mixture of the above isomers, so it is necessary to separate 1,4-dimethylnaphthalene isomer (1) from this mixture.However, dimethylnaphthalene isomers have similar boiling points and melting points. Therefore, it is generally difficult to separate these isomers by distillation.For this reason, conventionally, in order to separate 1,4-dimethylnaphthalene from a mixture of dimethylnaphthalene isomers, 1,4-dimethylnaphthalene is A crystallization method has been adopted that takes advantage of the phenomenon that 1,4-dimethylnaphthalene is slightly more difficult to crystallize than its isomers. However, even when attempting to separate 1,4-dimethylnaphthalene using this crystallization method, the resulting There was a serious problem that it was impossible to achieve a purity of 90% or higher.If high purity 1,4-dimethylnaphthalene could not be obtained, naphthalene-1,4 obtained from this 1,4-dimethylnaphthalene - Dicarboxylic acid does not have high purity, so even if you try to produce a synthetic polymer using this naphthalene 1,4-dicarboxylic acid, you will not be able to increase the degree of polymerization, and you will not be able to produce a polymer with the desired properties. It is not possible.

We obtained 1 from a dimethylnaphthalene isomer mixture.
, 4-dimethylnaphthalene, and found that dimethylnaphthalene has different molecular shapes depending on its structure, and that by utilizing this difference, specific dimethylnaphthalene, especially 1.4-dimethylnaphthalene, can be separated from a dimethylnaphthalene isomer mixture. We have completed the present invention by discovering scales that can efficiently separate αα-type isomers containing dimethylnaphthalene.

SUMMARY OF THE INVENTION The present invention is an attempt to solve the problems associated with the prior art as described above, and it is an object of the present invention to solve the problems associated with the prior art as described above. The present invention relates to a method for separating a specific isomer from a mixture of dimethylnaphthalene isomers, which allows αα type isomers to be separated efficiently and with high purity.

The method for separating dimethylnaphthalene isomers according to the present invention is as follows:
When separating a specific dimethylnaphthalene isomer from the αα type, ββ type, and αβ type dimethylnaphthalene isomer mixture shown below, the dimethylnaphthalene isomer is used as an adsorbent for alkali metals, alkaline earth metals, and rare earth metals. It is characterized in that it is brought into contact with X-type zeolite or Y-type zeolite that has been ion-exchanged with at least one metal ion selected from metals.

1.8-DHN 1.5-DHN 1.4-D
) INl, 2-DIN 1.66-0H1,7-D
HN 1.3-DHN In the present invention, the above αα type,
When separating a specific dimethylnaphthalene isomer from a mixture of αβ and ββ dimethylnaphthalene isomers,
Ion-exchanged isomer mixture with specific metal ions
Since it is brought into contact with type zeolite or Y type zeolite, a specific dimethylnaphthalene isomer, particularly 1,4-dimethylnaphthalene, can be separated efficiently and with high purity from the isomer mixture.

DETAILED DESCRIPTION OF THE INVENTION The method for separating dimethylnaphthalene isomers according to the present invention will be specifically described below.

In the present invention, when separating a specific dimethylnaphthalene isomer from a mixture of αα, αβ, and ββ dimethylnaphthalene isomers, the isomer mixture is ion-exchanged with a specific metal ion as an adsorbent. The dimethylnaphthalene isomer and the zeolite as an adsorbent will be explained below.

Dimethylnaphthalene isomers Dimethylnaphthalene has 10 types of isomers as shown above, and these isomers can be divided into αα type, αβ type, and ββ type depending on the positional difference of the methyl group as a substituent. No. 3
Classified as isomers of species.

Among these molecules, the αα type has the largest molecular knurling, followed by the αβ type and the ββ type, which become smaller in that order.

Among such dimethylnaphthalene isomers, it is desired to efficiently separate the αα type, particularly 1,4-dimethylnaphthalene, with high purity.

In the present invention, a mixture of dimethylnaphthalene isomers containing at least one of the above αα type, αβ type, and ββ type is used.

Adsorbent In order to separate and purify a specific dimethylnaphthalene from a dimethylnaphthalene isomer mixture in the present invention, this isomer mixture is brought into contact with an adsorbent.

Such absorbing agents include X-type zeolite or Y-type zeolite ion-exchanged with at least one metal ion selected from alkali metals, alkaline earth metals, and rare earth metals.
type zeolite is used.

Ion exchange of the X-type zeolite or the Y-type zeolite with the above metal ions can be carried out by conventionally known methods. For example, X-type zeolite or Y-type zeolite that has undergone pretreatment such as washing with water and calcination is immersed in an aqueous solution of a compound containing the above metal ions, heated, and then immersed again in a new aqueous solution of a compound containing the above metal ions. However, after repeating this operation several times, it may be washed with distilled water, dried, and then fired. It was confirmed by X-ray diffraction that the crystal structure of the X-type zeolite or Y-type zeolite was not destroyed, and the atomic The amount of metal ions displaced can be quantified by absorption analysis.

Metal ions used to replace zeolite include alkali metals such as potassium and rubidium, alkaline earth metals such as magnesium, calcium, strontium, and barium, lanthanum, cerium, neodymium,
Rare earth metals include promethium, samarium, europium, actinium, thorium, uranium, neptunium, protonium, and americium. Among these, calcium and strontium are particularly preferred.

As the adsorbent, X-type zeolite or Y-type zeolite is used as described above, and among these, X-type zeolite is particularly preferred.

- When such an adsorbent, X-type zeolite or Y-type zeolite, is brought into contact with a mixture of dimethylnaphthalene isomers, the smaller-shaped dimethylnaphthalene isomers preferentially depending on the size of the dimethylnaphthalene isomers. It is adsorbed. That is, as mentioned above, among the dimethylnaphthalene isomers, the αα type is the largest, followed by the α
The size decreases in the order of β-type and ββ-type, and therefore, among dimethylnaphthalene isomers, ββ-type isomer, that is, 2,3
-DMN, 2.6-DMN, and 2.7-DMN are most easily adsorbed. Then the αβ isomer, i.e. 1,2-
DMN, 1.6-DMN, 1.7-DMN, 1.3-D
MN is easily adsorbed and forms the αα isomer, i.e. 1.8-
DMN, 1.5-DMN, and 1.4-DMN are the least likely to be adsorbed.

Therefore, when a mixture of αα-type, αβ-type, and ββ-type dimethylnaphthalene isomers is brought into contact with X-type zeolite or Y-type zeolite, which is an adsorbent as described above, ββ-type, αβ-type, and αα-type are absorbed in this order. It will be done. For example, when a mixture containing the above isomers is brought into contact with an adsorbent, the αα type dimedylnaphthalene isomer mixture is the least likely to be adsorbed, so the contact residual liquid that remains without being adsorbed by the adsorbent contains more αα type isomers. Includes In particular, since 1,4-dimethylnaphthalene has the largest molecular shape among the αα-type isomers, many 1,4-dimethylnaphthalenes remain in the contact residual liquid, so using this method, dimethyl αα-type dimethylnaphthalene isomers, especially 1,4-dimethylnaphthalene, can be separated from a naphthalene isomer mixture.

-hββ type dimedylnaphthalene is preferentially adsorbed on the adsorbent X type zeolite or Y type zeolite,
Therefore, if this adsorbed ββ type dimethylnaphthalene is desorbed from the adsorbent, a liquid containing a large amount of ββ type dimethylnaphthalene will be obtained. dimethylnaphthalene isomers can be separated.

Also, even if it is an αα type dimethylnaphthalene isomer, 1
．． There is a slight difference in the adsorption properties of 4-DMN and 1.8-DMN to the adsorbent. Therefore, by utilizing the difference in the adsorption properties of each ↑1 zeolite within the same group, the present invention can be applied even if the isomers within the same group are αα type, αβ type, and ββ type. It can also be separated and purified to some extent using X-type zeolite or Y-type zeolite used in

The contact operation between the dimethylnaphthalene isomer mixture as described above and the metal ion-exchanged X-type zeolite or Y-type zeolite as an adsorbent can be carried out by any conventionally known method. I can do it. For example, a method of contacting using a fixed bed method, a method of contacting using a fluidized bed method, a method of contacting using a moving bed method, etc. can be adopted. The temperature during the contact treatment is usually in the range of 20 to 300°C, preferably room temperature to 150°C.

When the mixture containing the dimethylnaphthalene isomer is brought into contact with the X-type zeolite or the Y-type zeolite, the mixture containing the dimethylnaphthalene isomer can be brought into contact as it is, but if necessary, the dimethylnaphthalene isomer may be The contact can also be made in the form of a diluted solution with a solvent that does not inhibit adsorption of the body. Examples of diluent solvents include aliphatic hydrocarbon solvents such as )-heginane, n-hebutane, n-octane, and n-nonane; ethers such as diethyl ether and tetrahydrofuran;
In some cases, benzene, toluene, etc. are used.

The dimethylnaphthalene adsorbed on the X-type zeolite or Y-type zeolite which has been ion-exchanged with metal ions as an adsorbent in this way is desorbed from the adsorbent by performing a normal desorption operation. Specifically, the 1B2-linking operation includes, for example, ethanol, lower alcohols such as ethanol, acetone, benzene, toluene, chlorobenzene, dichlorobenzene, bromobenzene, diethylbenzene, trimedelbenzene, acetic acid, benzyl alcohol, phenol, cresol, and anisole. Examples include a method in which a desorbent such as the like is brought into contact with an adsorbent, a method in which an inert gas is passed through the adsorbent under heating, a method in which the adsorbent is heated under reduced pressure, and the like.

Among these desorption methods, a method of desorption using a desorption agent is preferred.

Of course, the dimethylnaphthalene isomer mixture and the adsorbent can be brought into contact multiple times.

Effects of the Invention In the present invention, when separating a specific dimethylnaphthalene isomer from a mixture of αα, αβ, and ββ dimethylnaphthalene isomers, the isomer mixture is separated from an X-type zeolite ion-exchanged with a specific metal ion or Since it is brought into contact with Y-type zeolite, a specific dimethylnaphthalene isomer, particularly 1,4-dimethylnaphthalene, can be efficiently separated from the above isomer mixture with high purity.

EXAMPLES The present invention will be explained below with reference to Examples, but the present invention is not limited to these Examples.

Example 1 1.4-DMN (αα isomer), 1.3-DMN
(αβ isomer) and 2.6-DMN (ββ isomer) were weighed out in an amount of 3.39 each, and they were added to 4 ml of hexane.
A mixed solution of dimethylnaphthalene isomers of equal concentration was prepared by dissolving 90 g of the dimethylnaphthalene isomers.

7'i Toyo W1da Co., Ltd. equipment 3X type zeolite (Na
By ion-exchanging XH (trade name Zeolum F-9) using strontium nitrate in the usual manner, 3r ion-exchanged 1% X-type zeolite (strondium exchange rate 87%)
It's a helmet. S r ion exchange X prepared in this way
Types of zeolite 1~ were calcined in air at 600''C for 2 hours and allowed to cool in a desiccator for about 2 hours.

The above-mentioned strontium ion-exchanged type
20° of a hexane solution of dimethylnaphthalene isomers containing DMN, 1,3-DMN, and 2,6-DMN was added to the flask. After 3 hours of being gently transported at air temperature, the concentration of each DMN isomer in the solution containing the dimethylnaphthalene isomer that remained unadsorbed by the adsorbent was measured by gas chromatography (2 m glass filled with PEG 6000). The adsorption rate of the DMN isomer was determined by analysis using a column). At this time, 1,3.5-triisopropylbenbin was used internally for analysis.The adsorption rate of each isomer is expressed as follows.

Adsorption rate (%) - D) IN isomer in the raw material - DMN isomer in the solution after adsorption [)) IN isomer source O''l The results are shown in Table 1.

Table 1 From Table 1, it can be seen that 2.6-DMN is adsorbed on zeolite at a high absorption rate, whereas 1.4-DMN is hardly adsorbed on zeolite.

Examples 2 to 9 1,4-DMN, 1,3-DMN
The adsorption selectivity of each isomer of 2,6-DMN was investigated.

The results are shown in Table 2 a) Example 2: Na-type 13X zeolite manufactured by Toyo Soen Co., Ltd. (trade name Zeolum "-9") b) Example 3: The above Na-type 13X zeolite was mixed with potassium ion-exchanged 13X zeolite (ion exchange rate 87%) C) Example 4...Ca type 13X zeolite ion exchanged with calcium (ion exchange rate 67%) d) Example 5 ...La-type 13X zeolite obtained by ion-exchanging the above Na! S213X zeolite with lanthanum iyne (ion exchange rate 44%) e) Example 6... Na321 manufactured by Union Carbide Co.
3Y zeolite (trade name: Lindo molecular sieves 5K40) f) Example 7: K 3% jl13Y zeolite (ion exchange rate 90%) obtained by ion exchange and moxibustion of the above Na type 13Y zeolite with potassium ions g) Example 8... Ca-type 13Y zeolite obtained by ion-exchanging the above Na-type 13Y zeolite with calcium ions (ion exchange rate 62%) h) Example 9... Ca-type 13Y obtained by ion-exchanging the above-mentioned Na-type 13Y zeolite with cerium ions Zeolite (ion exchange rate 56%) 622 Stopper type unit 1.4-DMN, 1.3-DMN and 2.
The adsorption selectivity of each isomer of 6-DMN was investigated.

The results are shown in Table-3.

a) Comparative Example 1: Na-type mordenite zeolite manufactured by Two-Tone (trade name Zeolon b) Comparative Example 2: Ca-type mordenite obtained by ion-exchanging the above zeolon with calcium (ion exchange rate 63%) C) Comparative Example 3...Molded in the Union Carbide type zeolite (trade name: Lindo Molecular Sieves 5K-45) d) Comparative Example 4...Ca type zeolite obtained by ion-exchanging the above-mentioned type zeolite with calcium (ion exchange rate 64) %) e) Comparative Example 5...Fuji Davison MA type zeolite C
Type a (generic name 5A type) f) Comparative example 6... Type A zeolite N manufactured by Fuji Davison
Type a (generic name 4A type) q) Comparative example 7: Type A zeolite manufactured by Showa Union Co., Ltd. (generic name 3A type) Example 10 1.5-DMN (αα isomer) as DMN isomer ),
1.6-DMN (11 αβ variants), 2.6-DMN
(ββ isomer) was selected, and the adsorption selectivity of strondium ion-exchanged type X zeolite was measured in the same manner as in Example 1, except that an equiconcentration mixed solution of n-hexane was prepared. The results are shown in Table 4.

Example 1] As a DMN isomer 1. B-DMN (αα isomer),
1.3-DMN (αβ isomer), 2.7-DMN
The adsorption selection ↑ 1 of calcium ion-exchanged type . The results are shown in Table-5.

A dimethylnaphthalene isomer mixture solution was prepared by dissolving 1.5 g of a dimethylnaphthalene mixture containing several kinds of dimethylnaphthalene isomers and monomethylnaphthalene as shown in Table 6 in 50 d of dry toluene.

5.0 g of the same calcium ion-exchanged type The composition of the solution containing the naphthalene isomer is shown in Table 6 in comparison with the composition of the raw material.

From Table 6, αα type 1.4-DMN remains in the solution without being adsorbed to the adsorbent zeolite, and 1.4-DMN remains in the solution after adsorption. It can be seen that it is contained in an extremely higher concentration than the original r1 solution.

Claims (5)

[Claims] (1) When separating a specific dimethylnaphthalene isomer from a dimethylnaphthalene isomer mixture, the dimethylnaphthalene isomer mixture is used as an adsorbent of at least one kind selected from alkali metals, alkaline earth metals, and rare earth metals. 1. A method for separating dimethylnaphthalene isomers, which comprises bringing them into contact with X-type zeolite or Y-type zeolite that has been ion-exchanged with metal ions. (2) The method according to claim 1, wherein the adsorbent is an X-type zeolite ion-exchanged with strontium ions or calcium ions. (3) The method according to claim 1 or 2, characterized in that αα-type dimethylnaphthalene isomers are separated from a dimethylnaphthalene isomer mixture. (4) The method according to claim 3, wherein the αα dimethylnaphthalene isomer is 1,4-dimethylnaphthalene. (5) The method according to claim 1 or 2, characterized in that αα-type dimethylnaphthalene isomers and ββ-type dimethylnaphthalene isomers are separated from a dimethylnaphthalene isomer mixture.