JPH05279272A - Method for isomerizing dialkylnaphthalene - Google Patents

Abstract

PURPOSE:To efficiently obtain a dialkylnaphthalene mixture having a composi tion close to a thermodynamically equilibrium value by isomerizing a specific dialkylnaphthalene in the presence of a crystalline nickel-containing metal losilicate catalyst. CONSTITUTION:One or more dialkylnaphthalenes selected form the group consisting of 1,5-dialkylnaphthalene, 1,6-dialkylnaphthalene and 2, 6- dialkylnaphthalene are isomerized in the presence of a catalyst of the formula R2/mO:xM2O3:yNiO:zSiO2:nH2O (R is alkali metal or alkaline earth metal having valence (m); (m) is 1-2;M is Al, Ga or B; (x) is 0-1; (y) is 0.01-10; (z) is 2-100; (n) is 1-20) at 200-380 deg.C preferably in the presence of a hydrogen gas. Reactions such as disproportionnation and intergroup isomerization are restricted to the minimum and isomerization in 2,6-group of dialkylnaphthalene mainly occurs to efficiently give a desired isomer. Cake is slightly precipitated on the surface of the catalyst, etc., during the reaction.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for isomerizing dialkylnaphthalene. Among them, isomerization suitable for industrially producing 2,6-dialkylnaphthalene, particularly 2,6-dimethylnaphthalene. It is about the method.

[0002]

BACKGROUND OF THE INVENTION There are many isomers of dialkylnaphthalene. For example, there are 10 isomers of dimethylnaphthalene, and these isomers can be classified into the following 4 groups. Generally, the intra-group isomerization reaction performed in each group is relatively easy, but inter-group isomerization to other groups is unlikely 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 the production of naphthalenedicarboxylic acid, 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 feed oil containing a dimethylnaphthalene isomer mixture as a main component. Furthermore, in order to utilize the raffinate after the separation, isomerization from another group to a group containing a 2,6-isomer (hereinafter sometimes referred to as “2,6 group”) is required. 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 the main component is obtained. If the isomerization reaction can be carried out 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%. Since it becomes a concentration, it is extremely efficient industrially.

In order to obtain 2,6-dimethylnaphthalene, an attempt to control isomerization only within the 2,6-group has been known for a long time, and a method using a mixture of hydrogen-type mordenite and acid clay as a catalyst. (Japanese Patent Publication Sho 55-4702
0), and a method using aluminoborosilicate (Table 1-503, 389).

[0006]

However, in the above method of controlling isomerization only within the 2,6-group,
Generally, the intra-group isomerization reaction is easier than the intra-group isomerization reaction, but inter-group isomerization other than intra-group isomerization, other disproportionation, and transalkylation It was very difficult to control side reactions such as. Further, there is a limit to the improvement of the reaction results even if the composition of the known catalyst or the production conditions are changed.

[0007]

Means for Solving the Problems The inventors of the present invention have been studying the isomerization method of dialkylnaphthalene for many years, and as one of the results of the research, all of the 10 kinds of oils usually obtained from a feed oil fraction are usually used. A method using a specific nickel-containing metallosilicate catalyst was proposed as a method of increasing the 2,6-isomer from a dimethylnaphthalene mixture containing isomers to a thermodynamic equilibrium concentration (about 14%) (Japanese Patent Application No. 232701). In the examples in the specification, 40
It shows a good isomerization reaction under the reaction temperature condition 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, it was surprisingly found that the reaction conditions were extremely excellent as the isomerization method in the 2,6-group. The invention has been reached. That is, the gist of the present invention is one or two selected from the group consisting of 1,5-dialkylnaphthalene, 1,6-dialkylnaphthalene and 2,6-dialkylnaphthalene.
At least one dialkylnaphthalene in the oxide molar ratio of the following general formula

[0009]

Embedded image R ₂ / mO: xM ₂ O ₃ : yNiO: zSiO ₂ : nH ₂ O (wherein R represents at least one alkali metal having an valence of m or an alkaline earth metal, 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 a crystalline nickel-containing metallosilicate catalyst represented by
A mixture of dialkylnaphthalene having a composition close to the thermodynamic equilibrium value of the group consisting of 1,5-dialkylnaphthalene, 1,6-dialkylnaphthalene and 2,6-dialkylnaphthalene, which is obtained by reacting in the temperature range of 380 ° C. And a method for isomerizing dialkylnaphthalene which is characterized in that

The present invention will be described in detail below. The dialkylnaphthalene as the isomerization reaction raw material of the present invention is 1,
One or more dialkylnaphthalene selected from the group consisting of 5-dialkylnaphthalene, 1,6-dialkylnaphthalene and 2,6-dialkylnaphthalene (groups 2,6) is 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 that it is close to the ratio corresponding to the thermodynamic equilibrium value between the three isomers, but the 2,6-isomer is industrially used. Therefore, when 2,6-isomerism is particularly desired to be obtained, it is preferable to use a raw material having a high concentration of 1,5-isomer or 1,6-isomer.

Examples of the alkyl group of dialkylnaphthalene include a methyl group, an ethyl group and an inpropyl group, but a methyl group is preferable. Further, the origin of the raw material of the dialkylnaphthalene is not particularly limited, and the dialkylnaphthalene may be separated from the aromatic hydrocarbon raw material oil, or may be obtained by synthesis from naphthalene or the like. Next, in the present invention, the solid acid catalyst used for isomerizing the above dialkylnaphthalene raw material is represented by the following general formula in oxide molar ratio.

[0012]

Embedded image R ₂ / mO: xM ₂ O ₃ : yNiO: zSiO ₂ : nH ₂ O (wherein R represents at least one alkali metal having an valence of m or an alkaline earth metal, 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. ) A crystalline nickel-containing metallosilicate represented by Here, as the crystalline nickel-containing metallosilicate, at least one kind of alkali containing nickel and at least a part or all of the nickel may be at a tetrahedral substitution position forming a zeolite skeleton, or having an atomized m It may be in the form of being ion-exchanged with the metal or the alkaline earth metal R or being present in the supported state in a covalent bond. The tetrahedral substitution position forming the zeolite skeleton is preferable.

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

Such crystalline nickel-containing metallosilicates are disclosed, for example, in JP-A-61-64333 or "Catalyst" Vol. 2, P.I. 81 (1986) and the like. Examples of the nickel salt used include nickel nitrate and nickel sulfate. In addition, examples of the raw material of the M component of the general formula of the catalyst include aluminum sulfate, gallium nitrate, boric acid, borate ester and the like. As a method for containing nickel, it is also possible to use a hydrothermal synthesis method or a method of impregnating these nickel salts or an ion exchange method to ion-exchange nickel to contain nickel. Furthermore, if necessary, elements 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 H-type (protonated) by a conventional ion exchange and calcination method and provided as a catalyst.

The crystalline nickel-containing metallosilicate thus obtained is extruded by mixing with a binder such as boehmite, alumina, kaolin or silica in an amount of usually 5 to 50% by weight, preferably 10 to 30% by weight. It may be molded into a granular, pellet-shaped, or spherical shape by a molding method or the like, and in that 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 a high activity for a long time, but can be regenerated by oxidizing treatment with an oxygen-containing gas or hydrogenating treatment with a hydrogen-containing gas after completion of the reaction.

In the present invention, the 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 reaction is set to 200 to 380 ° C, preferably 250 to 350 ° C. Below the reaction temperature, the isomerization reaction is slow and efficient,
Further, above the reaction temperature, the isomerization rate 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 pressure may be either normal pressure or increased pressure, and may be liquid phase or gas phase. The reaction system may be either a batch method or a continuous method. It should be noted that the reaction atmosphere is preferably in the presence of hydrogen gas from the viewpoint of maintaining the catalytic activity, because the catalytic activity is easily deteriorated in the absence of hydrogen.

[0017]

EXAMPLES The present invention will be specifically described below with reference to examples, but the present invention is not limited to the following examples as long as the gist thereof is not exceeded. The products were analyzed by gas chromatography, and the amount of coke was analyzed by the combustion method. Example 1 Aluminum sulfate hydrate (Wako Pure Chemical Industries, Ltd.) 10.6
g, nickel sulfate (manufactured by Wako Pure Chemical Industries, Ltd.) 8.9 g, sulfuric acid (manufactured by Kokusan Kagaku Co., Ltd.) 24.8 g, tetrapropylammonium bromide (TPABr) (Tokyo Kasei)
23.0 g dissolved in 240 g of water was used as solution A, water glass No. 3 (manufactured by Kishida Chemical Co., Ltd.) and water 181 g were mixed 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 (95% purity from Junsei Kasei Co., Ltd.) in water 4
What was melt | dissolved in 17g was set as C liquid.

Solution A and solution C were added to solution B with stirring, and the resulting gel was stirred for 30 minutes. Next, after standing for 30 minutes and cooling, the mixture was charged into a 2 liter autoclave and heated to 156 ° C. from the greenhouse for 1.5 hours with stirring. Then, the temperature was raised to 216 ° C. at a constant rate for 3 hours and 10 minutes. After cooling, the slurry is filtered, washed with water, and further thoroughly washed with warm water to obtain nickel-containing aluminosilicate powder 7
8.3 g was obtained. The filterability was extremely good, and almost no adhesion was observed on the inner wall of the autoclave. The SiO ₂ / Al ₂ O ₃ ratio after synthesis was 72, the SiO ₂ / NiO ₂ ratio was 94, and the charging ratio (SiO ₂ / Al ₂ O ₃ = 79 _, Si
Was _{O 2 / NiO 2 = 40)} . Furthermore, in X-ray diffraction,
It exhibits a pure ZSM-5-like pattern and also has a NiO
No peak derived from was detected.

The nickel-containing aluminosilicate thus obtained was subjected to 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 a diffraction method. This process was repeated twice more.
After the ion exchange treatment, it was washed with warm water and dried at 120 ° C. for 24 hours. Then, it was baked at 540 ° C. for 5 hours under air circulation.
Obtained H-type nickel-containing aluminosilicate SiO
_{The 2} / Al ₂ O ₃ ratio was 69 and the SiO ₂ / NiO ₂ ratio was 86. This was tablet-molded, and the powder was aligned with 10 to 20 mesh and used as a catalyst in 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 normal pressure at a hydrogen flow rate of 1.5 l / hr, 2,6-dimethylnaphthalene (purity 99.9%) 0.76 g / hr,
It was carried out for 8 hours. The average reaction results at this time are shown in Table 1. In Table-1, dimethylnaphthalene is "DMN"
I abbreviated. The “loss rate 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 ratio” refers to 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 is shown in Table 1.

Further, the isomer composition in the 2,6-group of dimethylnaphthalene as the reaction product in Example 1 is 2,6:
1,6 body: 1,5 body = 50.9: 43.8: 5.3, which is a thermodynamic equilibrium value of 47.6: 43.7: 8.7 calculated by 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 in Example 1 was 400 ° C.

Comparative Example 2 Silica sol ("Cataloid S-3, Catalysts & Chemicals Co., Ltd.")
Silica gel 12 obtained by evaporating and drying (0H ″) at 120 ° C.
5g (SiO₂2.0 mol) as 120 g of demineralized water
After mixing and processing in a lab mill for 2 hours, 1 liter capacity
It was washed in a beaker and adjusted to a total amount of 500 g. This
This was treated with a homogenizer for 40 minutes. Aluminate
Thorium aqueous solution (Sumitomo Chemical Co., Ltd., “NA-17
0 ", Al ₂O₃ 19.12%, Na₂O 19.5
2% included), NaOH (Junsei Kagaku Co., Ltd., 93% purity)
10.1 g, tetra-n-propyl ammonium hydroxide
Looxide aqueous solution (Tokyo Chemical Industry Co., Ltd., 1.126)
^N) Add a solution of 14.2 g dissolved in 237 g of water,
Further, it is treated with a homogenizer for 3 minutes to synthesize zeolite.
For slurry. This is a 2-liter volume induction induction type
Charge into an autoclave, at 125-7 ° C, 60 rpm
After aging for 4.5 hours, the temperature was raised to 200 ° C. and 400 rpm
The reaction was carried out for 12 hours under the conditions. After cooling the reaction generation part,
Filter, wash with water and wash with warm water until the pH of the filtrate reaches 8.
Washing (up to 80 ° C.) was performed. Si synthesized as described above
O₂/ Al₂O₃= 25 H-ZSM-5 as a catalyst
An experiment was conducted 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]

INDUSTRIAL APPLICABILITY According to the present invention, reactions such as disproportionation and inter-group isomerization are suppressed to a minimum, and dialkylnaphthalene 2,
Since the isomerization in the 6-group mainly occurs, the desired isomer can be efficiently obtained. Further, there is little precipitation of coke on the surface of the catalyst during the reaction, and it has great industrial utility value.

─────────────────────────────────────────────────── ─── Continuation of the front page (51) Int.Cl. ⁵ Identification code Office reference number FI technical display location // C07B 61/00 300

Claims (1)

[Claims] 1. A 1,5-dialkylnaphthalene, 1,
One or more dialkylnaphthalene selected from the group consisting of 6-dialkylnaphthalene and 2,6-dialkylnaphthalene are represented by the following general formula in oxide molar ratio: R ₂ / mO: xM ₂ O _{3 : yNiO: zSiO 2: nH 2} O ( wherein, R is at least one alkali metal or an alkaline earth metal having a valence m, 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 a crystalline nickel-containing metallosilicate catalyst represented by
A mixture of dialkylnaphthalene having a composition close to the thermodynamic equilibrium value of the group consisting of 1,5-dialkylnaphthalene, 1,6-dialkylnaphthalene and 2,6-dialkylnaphthalene, which is obtained by reacting in the temperature range of 380 ° C. A method for isomerizing dialkylnaphthalene, which comprises: