JP3139119B2 - Method for isomerizing dialkylnaphthalene - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a process for isomerizing dialkylnaphthalene, and more particularly to a process for producing 2,6-dialkylnaphthalene, particularly 2,6-dimethylnaphthalene, which is suitable for industrially advantageous production. It is about the method.

[0002]

2. Description of the Prior Art Dialkylnaphthalene has a number of isomers. For example, dimethylnaphthalene has ten isomers, and these isomers can be classified into the following four groups. In general, the intra-group isomerization reaction performed within each group is relatively easy, while the inter-group isomerization to other groups is less likely to occur. (I) 1,5-, 1,6-, 2,6-isomer (II) 1,8-, 1,7-, 2,7-isomer (III) 1,4-, 1,3- , 2,3-isomer (IV) 1,2-isomer

One of the main uses of dimethylnaphthalene is in the production of naphthalenedicarboxylic acids, in which the 2,6-isomer is particularly preferred. When it is desired to obtain the 2,6-isomer, the 2,6-isomer is generally separated from a feedstock containing a dimethylnaphthalene isomer mixture as a main component. Further, in order to utilize the raffinate after the separation, it is necessary to isomerize the other group into a group containing 2,6-isomer (hereinafter sometimes referred to as “group 2,6”), Such an isomerization reaction is achieved by a specific zeolite-based catalyst (JP-A-58-210301, JP-A-59-88, 433, etc.). However, in this method, the thermodynamic equilibrium concentration in all the isomers of the 2,6-isomer is only about 14%, so that it is not always efficient as a method for obtaining the 2,6-isomer.

On the other hand, in recent years, a method of synthesizing dialkylnaphthalene, particularly dimethylnaphthalene, from alkylbenzenes has attracted attention. According to this method, an isomer mixture of dimethylnaphthalene containing only the 2,6 group containing the desired 2,6-isomer as a main component is obtained. If the isomerization reaction can be performed only in the 2,6-group using the isomer mixture as a raw material, the thermodynamic equilibrium concentration of the 2,6-isomer in the 2,6-group is as high as about 50%. The concentration is extremely efficient industrially.

[0005] In order to obtain 2,6-dimethylnaphthalene, attempts to control isomerization only within the 2,6-group have been known for a long time, and a method using a mixture of hydrogen-type mordenite and acid clay as a catalyst has been known. (Japanese Patent Publication 55-4702
0) and a method using an aluminoborosilicate (Japanese Patent Laid-Open No. 1-503, 389).

[0006]

However, in the above method for controlling isomerization only within the 2,6-group,
In general, although intragroup isomerization is easier than intergroup isomerization, intergroup isomerization other than intragroup isomerization, other disproportionation, and transalkylation It was very difficult to control such side reactions. Further, even if the composition of the known catalyst, the production conditions, and the like are changed, there is a limit in improving the reaction results.

[0007]

Means for Solving the Problems The inventors of the present invention have been studying a method for isomerizing dialkylnaphthalene for many years. As a method of increasing the 2,6-isomer to a thermodynamic equilibrium concentration (about 14%) from a dimethylnaphthalene mixture containing an isomer, a method using a specific nickel-containing metallosilicate catalyst has been proposed (Japanese Patent Application No. Hei. 232701). In the example in the specification, 40
A good isomerization reaction is shown at a reaction temperature of 0 ° C.

However, after that, when the investigation was continued on the basis of the above-mentioned method using the nickel-containing metallosilicate catalyst, surprisingly, an extremely excellent reaction condition was found as an isomerization method within the 2,6-group. The invention has been reached. That is, the gist of the present invention is to provide one or two selected from the group consisting of 1,5-dialkylnaphthalene, 1,6-dialkylnaphthalene and 2,6-dialkylnaphthalene.
At least one kind of dialkylnaphthalene is represented by the following general formula in an oxide molar ratio.

[0009]

Embedded image R ₂ / mO: xM ₂ O ₃ : yNiO: zSiO ₂ : nH ₂ O (wherein, R represents at least one alkali metal or an alkaline earth metal having a valence of m, and m represents 1 ~ 2,
M represents at least one of aluminum, gallium, and boron, x represents 0 to 1, y represents 0.01 to 10, z represents 2 to 100, and n represents 1 to 20. ) In the presence of the crystalline nickel-containing metallosilicate catalyst represented by
Reacting in a temperature range of 380 ° C. to convert the dialkylnaphthalene into a dialkylnaphthalene mixture having a composition close to the thermodynamic equilibrium value of the group consisting of 1,5-dialkylnaphthalene, 1,6-dialkylnaphthalene and 2,6-dialkylnaphthalene And a method for isomerizing dialkylnaphthalene.

Hereinafter, the present invention will be described in detail. The dialkylnaphthalene as the isomerization reaction raw material of the present invention is
One or more dialkylnaphthalenes selected from the group consisting of 5-dialkylnaphthalene, 1,6-dialkylnaphthalene and 2,6-dialkylnaphthalene (groups 2 and 6) are usually used in an amount of 50% or more, preferably 80% or more. %
The above is included. The ratio of the isomers in the 2,6-group is not particularly limited, except for those close to the ratio corresponding to the thermodynamic equilibrium value among the three isomers. In particular, when it is desired to obtain 2,6-isomer, it is preferable to use 1,5 or 1,6 isomer having a high concentration as a raw material.

The alkyl group of the dialkylnaphthalene is exemplified by a methyl group, an ethyl group, an inpropyl group and the like, and is preferably a methyl group. Further, the origin of the dialkylnaphthalene is not particularly limited, and the dialkylnaphthalene may be separated from an aromatic hydrocarbon feedstock or synthesized from naphthalene or the like. Next, in the present invention, as a solid acid catalyst used for isomerizing the above-mentioned dialkylnaphthalene raw material, an oxide molar ratio represented by the following general formula:

[0012]

Embedded image R ₂ / mO: xM ₂ O ₃ : yNiO: zSiO ₂ : nH ₂ O (wherein R represents at least one alkali metal or an alkaline earth metal having a valence of m, and m Is 1
2, M represents at least one of aluminum, gallium, and boron, x is 0 to 1, y is 0.01 to 10,
z represents 2 to 100 and n represents 1 to 20. The crystalline nickel-containing metallosilicate represented by) is used. Here, the crystalline nickel-containing metallosilicate may contain nickel, and at least a part or all of the nickel may be at a tetrahedral substitution position forming a zeolite skeleton, or at least one kind of alkali having atomization m. It may be in a form ion-exchanged with a metal or an alkaline earth metal R, or may exist covalently in a supported state. Preferably, the tetrahedral substitution position forming the zeolite skeleton is better.

Further, the crystalline nickel-containing metallosilicate of the present invention has a molar ratio de SiO ₂ / M ₂ O ₃ , that is, z / x of usually 3 or more, preferably 5 or more. ₂ / NiO, that is, z / y is usually 5
2,000 or less, preferably 2000 or less.
And such metallosilicate is structurally mordenite, faujasite, omega, beta, ZSM-5 type,
It can have a structure such as ZSM-8 type, ZSM-11 type, etc.
More preferably, it has a ZSM-5 type structure.
That is, as the crystalline nickel-containing metallosilicate of the present invention, the crystalline nickel-containing metallosilicate has an X-ray diffraction pattern of ZSM-5 type zeolite and has a crystallographic skeleton containing silicon, nickel and aluminum or silicon and nickel. Nickel-containing metallosilicates are most preferred.

Such a crystalline nickel-containing metallosilicate is disclosed, for example, in JP-A-61-64333 or "Catalyst" Vol. 2, P. 81 (1986) and the like. Examples of the nickel salt to be used include nickel nitrate and nickel sulfate. In addition, examples of the raw material of the component M of the general formula of the catalyst include aluminum sulfate, gallium nitrate, boric acid, and borate ester. As a method of containing nickel, a method of impregnating these nickel salts or an ion exchange method of ion-exchanging nickel may be used, in addition to a hydrothermal synthesis method. Further, if necessary, an element such as molybdenum, tungsten, vanadium, iron, bismuth, copper or cobalt may be added to the catalyst of the present invention in the form of sulfide or oxide. The addition amount of such a compound may be about 0.5 to 20% by weight. The catalyst used in the present invention is converted into H-type (proton) by a conventional ion exchange and calcining method, and used as a catalyst.

The crystalline nickel-containing metallosilicate obtained in this manner is extruded by mixing a binder such as boehmite, alumina, kaolin or silica, usually in an amount of about 5 to 50% by weight, preferably about 10 to 30% by weight. It may be used by molding into granules, pellets, spheres or the like by a molding method or the like. In this case, the particle size is not particularly limited, but is usually about 0.5 to 5 mm, and the surface area of the catalyst is generally It is preferable to select and use from the range of 200 to 700 m ² / g. The crystalline nickel-containing metallosilicate catalyst maintains high activity for a long time, but can be regenerated after the reaction by oxidation treatment with an oxygen-containing gas or hydrogenation treatment with a hydrogen-containing gas.

In the present invention, such a crystalline nickel-containing metallosilicate is used as a catalyst to react the above-mentioned dialkylnaphthalene. The present invention is characterized in that the reaction temperature of such a reaction is set at 200 to 380 ° C, preferably 250 to 350 ° C. Below the reaction temperature, the isomerization reaction is slow and efficient,
If the temperature is higher than the reaction temperature, the isomerization ratio outside the 2,6-group increases, and it becomes difficult to obtain a dialkylnaphthalene mixture having a composition close to the thermodynamic parallel value of the 2,6-group. The reaction can be carried out under normal pressure or under pressure, and can be carried out in either a liquid phase or a gas phase. The reaction method may be either a batch method or a continuous method. In the reaction atmosphere, the catalytic activity is likely to be degraded in the absence of hydrogen. Therefore, the presence of hydrogen gas is preferable from the viewpoint of maintaining the catalytic activity.

[0017]

EXAMPLES Hereinafter, the present invention will be described in detail with reference to examples, but the present invention is not limited to the following examples unless it exceeds the gist of the invention. The product was analyzed by gas chromatography, and the coke amount was analyzed by a combustion method. Example 1 Aluminum sulfate hydrate (Wako Pure Chemical Industries, Ltd.) 10.6
g, nickel sulfate (8.9 g, manufactured by Wako Pure Chemical Industries, Ltd.), 24.8 g of sulfuric acid (manufactured by Kokusan Chemical Co., Ltd.), tetrapropylammonium bromide (TPABr) (Tokyo Chemical Industry Co., Ltd.)
23.0 g dissolved in 240 g of water was used as solution A, and a mixture of 276 g of water glass No. 3 (manufactured by Kishida Chemical Co., Ltd.) and 181 g of water was used as solution B, and sodium chloride (Kishida Chemical Co., Ltd.) 105.3 g, sulfuric acid 11.4
g, tetrapropylammonium bromide 8.6 g,
Sodium hydroxide (Junsei Chemical Co., Ltd., 95% purity) is added to water 4
The solution dissolved in 17 g was designated as solution C.

Solution A and solution C were added to solution B with stirring, and the resulting gel was stirred for 30 minutes. Next, after leaving it to stand for 30 minutes and cooling, it was charged into a 2 l autoclave, heated from a greenhouse to 156 ° C. in 1.5 hours under stirring, and then heated at a constant rate to 216 ° C. in 3 hours and 10 minutes. After cooling, the slurry was filtered, washed with water, and further sufficiently washed with warm water to obtain a nickel-containing aluminosilicate powder 7.
8.3 g were obtained. The filterability was very good, and almost no adhesion was observed on the inner wall of the autoclave. The SiO ₂ / Al ₂ O ₃ ratio after the synthesis was 72, the SiO ₂ / NiO ₂ ratio was 94, and the charge ratio (SiO ₂ / Al ₂ O ₃ = 79 _, Si
Was _{O 2 / NiO 2 = 40)} . Furthermore, in X-ray diffraction,
It exhibits a pattern similar to pure ZSM-5 and
Was not detected.

The obtained nickel-containing aluminosilicate was subjected to an ion exchange treatment using ammonium nitrate having a concentration of 1.25 M at a solid-liquid ratio of 1/10 (g / ml) at 100 ° C. for 2 hours by diffraction. This process was repeated twice later.
After the ion exchange treatment, the substrate was washed with warm water and dried at 120 ° C. overnight. Next, it was calcined at 540 ° C. for 5 hours under air flow.
SiO of the obtained H-type nickel-containing aluminosilicate
_{The 2} / Al ₂ O ₃ ratio was 69 and the SiO ₂ / NiO ₂ ratio was 86. This was tablet-molded, adjusted to 10 to 20 mesh, and used as a catalyst for the reaction.

4.8 g of the above catalyst was placed in a glass reaction tube having an inner diameter of 20 mm, and kept at 300 ° C. under a hydrogen stream. The reaction was carried out under a normal pressure at a hydrogen flow rate of 1.5 l / hr, a 2,6-dimethylnaphthalene (purity of 99.9%) 0.76 g / hr,
Performed for 8 hours. The average reaction results at this time are shown in Table 1. In Table 1, dimethylnaphthalene is referred to as “DMN”.
Abbreviated. The “loss ratio outside the 2,6-group” indicates the ratio of isomers other than the 2,6-group to the total dimethylnaphthalene in the reaction product. "Disproportionation rate" indicates the ratio of the total amount of naphthalene, methylnaphthalene, and trimethylnaphthalene in the reaction product. . The amount of coke accumulated on the catalyst after the reaction was measured, and the amount of coke with respect to the amount of catalyst was shown in Table 1.

Further, the isomer composition in the 2,6-group of dimethylnaphthalene as a reactant in Example 1 is 2,6 isomers:
1,6: 1,5 = 50.9: 43.8: 5.3, and 47.6: 43.7: 8.7 of the thermodynamic equilibrium value obtained by calculation at the above reaction temperature. Was close to. Comparative Example 1 Table 1 shows the results of an experiment conducted in the same manner as in Example 1 except that the reaction temperature was changed to 400 ° C.

Comparative Example 2 Silica sol (catalyst, S-3)
0H ″) is evaporated to dryness at 120 ° C. to obtain silica gel 12
5g (SiO_Two2.0 mol) and 120 g of demineralized water.
After mixing and treating in a lab mill for 2 hours, 1 liter
, And the total amount was adjusted to 500 g. This
This was treated with a homogenizer for 40 minutes. Na aluminate
Thorium aqueous solution (Sumitomo Chemical Industries, Ltd., “NA-17
0 ", Al _TwoO_Three 19.12%, Na_TwoO 19.5
2%), NaOH (Junsei Chemical Co., Ltd., 93% purity)
10.1 g, tetra-n-propyl ammonium hydride
Aqueous solution of oxide (Tokyo Chemical Industry Co., Ltd., 1.126)
^NA) a solution of 14.2 g in 237 g of water,
Zeolite synthesis by further treating with a homogenizer for 3 minutes
Slurry. This is a 2 liter induction stirring type
At 125 to 7 ° C at 60 rpm
After aging for 4.5 hours, the temperature was raised to 200 ° C. and 400 rpm
The reaction was performed under the conditions for 12 hours. After cooling the reaction generator,
Filter, wash with water and wash with warm water until the pH of the filtrate reaches 8.
(〜80 ° C.) washing was performed. Si synthesized as described above
O_Two/ Al_TwoO_Three= 25 as a catalyst,
An experiment was performed in the same manner as in Example 1 except that the reaction temperature was 350 ° C.
The results obtained are shown in Table 1.

[0023]

[Table 1]

[0024]

According to the present invention, reactions such as disproportionation and intergroup isomerization are suppressed to a minimum, and 2,2
6- The desired isomer can be efficiently obtained by mainly causing isomerization within the group. Further, there is little precipitation of coke on the catalyst surface or the like at the time of the reaction, and there is a great industrial value.

Continuation of the front page (56) References JP-A-4-1122841 (JP, A) JP-A-49-87651 (JP, A) JP-A-49-41351 (JP, A) JP-B-50-2978 (JP, A) , B1) JP 48-1060 (JP, B1) JP 1-503389 (JP, A) (58) Fields investigated (Int. Cl. ⁷ , DB name) C07C 5/27 C07C 15/24

Claims (1)

(57) [Claims] 1. A 1,5-dialkylnaphthalene, 1,1
One or more dialkylnaphthalenes selected from the group consisting of 6-dialkylnaphthalene and 2,6-dialkylnaphthalene are represented by the following general formula in an oxide molar ratio: R ₂ / mO: xM ₂ O ₃ : YNiO: zSiO ₂ : nH ₂ O (wherein, R represents at least one alkali metal or an alkaline earth metal having a valence of m, and m is 1-2.
M represents at least one of aluminum, gallium, and boron, x represents 0 to 1, y represents 0.01 to 10, z represents 2 to 100, and n represents 1 to 20. ) In the presence of the crystalline nickel-containing metallosilicate catalyst represented by
Reacting in a temperature range of 380 ° C. to convert the dialkylnaphthalene into a dialkylnaphthalene mixture having a composition close to the thermodynamic equilibrium value of the group consisting of 1,5-dialkylnaphthalene, 1,6-dialkylnaphthalene and 2,6-dialkylnaphthalene A process for isomerizing dialkylnaphthalene, characterized by obtaining