JPH083078A - Method for producing 2,6-dimethylnaphthalene - Google Patents

Abstract

(57) [Summary] [Purpose] 2-methyl-1- (p-tolyl) -butane,
Alternatively, 2-methyl-1- (p-tolyl) -butene or a mixture thereof is used as a raw material to carry out a cyclization dehydrogenation reaction to obtain 2,6-dimethylnaphthalene, which is a useful polymer raw material, in high yield and high selection. A method of manufacturing is provided. [Structure] Hydrotalcite catalyst, or Periodic Table I
At least 1 element selected from Group a, Group VIII, and Group IVb
Cyclodehydrogenation using a catalyst containing hydrotalcite as a carrier, which contains certain elements.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for producing 2,6-dimethylnaphthalene which is a raw material of useful polymer materials. More specifically, 2-methyl-1- (p-tolyl)
It relates to the economical production of 2,6-dimethylnaphthalene by cyclodehydrogenation of -butane or 2-methyl-1- (p-tolyl) -butene, or mixtures thereof.

[0002]

2. Description of the Related Art 2,6-Dimethylnaphthalene is known to be separated from coal tar fraction, heavy catalytic reforming oil, or LCO of FCC fraction, or to methylate naphthalene or monomethylnaphthalene. Has been. However, these methods are said to be economically disadvantageous because they contain a large amount of 10 isomers of dimethylnaphthalene and require complicated separation and purification and isomerization steps. .

Further, JP-A-50-17983, JP-A-50-17985, JP-B-50-17983, JP-B-50-17985, JP-B-50-22550, and JP-B-50-22551 are mentioned. , 5- (O-tolyl) -pentene-2 is used as a raw material to produce dimethylnaphthalene, but this method also produces 2,6-,
It is obtained as an isomer such as 1,6-, 1,5-dimethylnaphthalene, and requires an isomerization step and a purification step.

On the other hand, 2-methyl-1- (p-tolyl)-
As a technique for producing 2,6-dimethylnaphthalene from butene or 2-methyl-1- (p-tolyl) -butane as a raw material, Japanese Patent Publication No. 51-1701 and Japanese Patent Publication No. 53-
No. 5292 can be mentioned, but these are 2, 6
-The problem is that the yield of dimethylnaphthalene is low and the concentration of other isomers is also high. In addition, JP-A-3-25
1545, JP-A-3-173834, JP-A4-1
Although similar reaction examples are shown in JP-A-08742 and JP-A-5-229969, toxic lead, volatile indium and the like are used as a catalyst, which poses a safety problem. Further, since alumina is used as a carrier, side reactions due to decomposition and isomerization are problems. Furthermore, when 2-methyl-1- (p-tolyl) -butene is used as a raw material, a good yield is shown, but when 2-methyl-1- (p-tolyl) -butane is used as a raw material, However, there are problems such as a decrease in yield.

[0005]

SUMMARY OF THE INVENTION 2-Methyl-1- (p
When -tolyl) -butene is used as the raw material, the cyclodehydrogenation reaction occurs relatively easily, and even if the conventional catalyst has a high conversion rate,
A high selectivity can be achieved. However, even higher selectivity is required in order to increase economic efficiency. On the other hand, when 2-methyl-1- (p-tolyl) -butane is used as the raw material,
Due to its low reactivity, its conversion is more difficult,
It has lower conversion and lower selectivity than 2-methyl-1- (p-tolyl) -butene.

In particular, the present invention uses 2-methyl-1- (p-tolyl) -butane as a raw material at a high conversion rate and a high selectivity of 2,2.
It is an object to provide a method for producing 6-dimethylnaphthalene.

[0007]

The present inventors have found that 2-methyl-1- (p-tolyl) -butane, or 2-methyl-
As a result of intensive studies on the reaction for producing 2,6-dimethylnaphthalene by cyclization dehydrogenation reaction using 1- (p-tolyl) -butenes or a mixture thereof, hydrotalcite or a periodic Table Ia, VIII
By using a hydrotalcite catalyst supporting at least one element selected from Group IV and Group IVb elements,
It was found that 2,6-dimethylnaphthalene can be produced with high conversion and high selectivity. Hereinafter, the present invention will be described in detail.

The present invention uses hydrotalcite as a catalyst, which is Mg ₆ Al ₂ (OH) ₁₆ .C.
It has a compositional formula represented by O ₃ · 16H ₂ O and 2
It is a layered compound composed of a valent metal and a trivalent metal. It is known that there are several types in nature, and combinations of divalent and trivalent metals and those having different composition ratios can also be obtained by synthetic methods. When it is calcined at a high temperature, it has a high surface area and is solid basic.

Generally, 2-methyl-1- (p-tolyl)
When -butane or 2-methyl-1- (p-tolyl) -butene is subjected to a cyclization dehydrogenation reaction using alumina, the production amount of the target 2,6-dimethylnaphthalene is small,
Other reactions, such as decomposition, polymerization, isomerization, occur preferentially. In addition, when the same reaction is performed using magnesia,
The conversion rate is low and almost no target compound is obtained. Also, when other metal oxides such as iron oxide, chromium oxide, cobalt oxide, and nickel oxide are used, decomposition and polymerization proceed extremely, and they do not function as a catalyst. In the case of alumina, for example, these causes are acidic catalysts having a high surface area, and therefore, the reaction activity is high, but it is considered that the reaction such as decomposition due to the acid points on the surface takes precedence. In the case of magnesia, on the contrary, since it has a low surface area and basicity, it is considered that the reaction activity is reduced but the decomposition reaction is suppressed. In the case of other metal oxides, it is considered that the inherent performance of the compound, for example, dehydrogenation ability and decomposition ability is the cause. That is, 2-methyl-1- (p-tolyl) -butane, or 2-methyl-1
In order to carry out the cyclodehydrogenation reaction using-(p-tolyl) -butene as a raw material, it is necessary to develop a catalyst incorporating the advantages of the catalyst as described above. In other words, it is desired to develop a catalyst having a high surface area and less excessively strong acid sites on the surface, and further a catalyst having dehydrogenation ability and cyclization ability.

The hydrotalcite used in the present invention is represented by the following compositional ratio. [M ²⁺ _(1-X) M ³⁺ _X (O
H) ₂ ] ^{X +} [A ⁿ⁻ _{X / n} · ZH ₂ O] ^X− M ²⁺ is a divalent metal ion, and is Mg ²⁺ , Mn ²⁺ , Co ²⁺ , Fe ²⁺ , Ni ²⁺ , Z.
^Examples thereof include n ²⁺ and Cu ²⁺ . M ³⁺ is a trivalent metal ion, and is Al ³⁺ , Cr ³⁺ , Mn ³⁺ , Fe ³⁺ , In ³⁺ , Co ³⁺
Etc. The divalent metal and the trivalent metal are not limited to one kind and may be a mixture of plural kinds. X
Is in the range of 0.09 ≦ X ≦ 0.33. A is an anion, and examples thereof include inorganic anions containing CO ₃ ²⁻ and SO ₄ ²⁻ , organic anions, or heteropolyanions.
The hydrotalcite in the present invention is synthesized by a conventional method. For example, Journal of Catalog
sis, Vol. 94, page 547, and Vol. 101, Vol. 3 of the same paper.
Although illustrated on page 52, the synthesis method is not particularly limited. Hydrotalcite is a layered compound composed of a positively charged basic layer having a structure similar to brucite [Mg (OH) ₂ ] and a negatively charged intermediate layer composed of an anion such as CO ₃ ²⁻ and interlayer water. Therefore, when this is heated, desorption of interlayer water, condensation dehydration of hydroxyl groups bonded to metal ions, and desorption of anions occur, resulting in a high surface area. This heating temperature is 300-7
The temperature is 00 ° C, more preferably 400 to 600 ° C. The heating time is sufficient for the dehydration and deanion reactions to proceed,
1 to 30 hours is suitable, and more preferably 2 to 20 hours.

In the method for preparing the catalyst of the present invention, the elements of Group Ia, Group VIII and Group IVb of the Periodic Table can be added to hydrotalcite as long as each component is uniformly dispersed in hydrotalcite. There is no particular limitation. For example, a method of impregnating these metal salt solutions with hydrotalcite, or a method of ion-exchange, a method of impregnating heat-treated hydrotalcite into these metal salt solutions, or a method of ion-exchanging them, or a method of synthesizing these during hydrotalcite synthesis. Various methods such as a method of simultaneously adding the metal salt solution, a method of kneading, and the like can be used.

In the catalyst of the present invention, the loading amount of the elements of Group Ia, Group VIII, and Group IVb of the periodic table on the hydrotalcite is 0.01 to 10% by weight, preferably 0. It is from 05 to 5.0% by weight. When the amount is less than that, the dehydrogenation ability and cyclization ability of the catalyst are not sufficient, and 2-methyl-1- (p-tolyl) -butane or 2-methyl-
If the reaction conversion rate of 1- (p-tolyl) -butene becomes smaller, and if it is more than that, isomerization or demethylation of the product proceeds, and further, a large amount of expensive metal is used. Not practical.

Platinum, palladium,
In the case of supporting tin or an alkali metal compound, for example, as a platinum source, platinum chloride, platinum nitrate, platinum acetate, chloroplatinic acid, sodium chloroplatinic acid, sodium chloroplatinum, or potassium chloroplatinum dissolved in a suitable solvent such as water, alcohol, or ketone. The tetraammine platinum complex is preferably used. Further, as a palladium source, water, alcohol, palladium chloride dissolved in a suitable solvent such as a ketone, palladium nitrate, palladium acetate, palladium chloride acid, sodium palladium chloride,
Palladium potassium chloride and tetraammine palladium complex are preferably used. As the tin source, tin chloride, stannic chloride, tin triflate, and alkyl tin dissolved in a suitable solvent such as water, alcohol, ketone, or ether are preferably used. As the lithium source, lithium chloride, lithium nitrate, lithium acetate or alkyllithium dissolved in a suitable solvent such as water, alcohol or ether is preferably used.

The catalyst precursor mixture prepared as described above is subjected to treatments such as drying, calcination, molding and reduction treatment to obtain the catalyst of the present invention. Drying is performed at room temperature or higher, more preferably at 60 to 130 ° C., and when firing is performed at 300
-700 degreeC, More preferably, it is 400-600 degreeC.
In the case of molding, methods such as tablet molding and extrusion molding are adopted. As a reduction treatment method, 300 to 700 ° C.
And a method of treating with a reducing agent such as sodium borohydride or hydrazine.

Using the catalyst of the present invention, 2-methyl-1-
(P-tolyl) -butane, or 2-methyl-1- (p
When 2,6-dimethylnaphthalene is produced by cyclodehydrogenation reaction using -tolyl) -butene or a mixture thereof as a raw material, the reaction method may be either batch type or continuous type. As a continuous method, various reactor types such as a fixed bed flow type reactor, a fluidized bed type reactor, a continuous tank type reactor, a fixed bed type reactive distillation type reactor and a boiling bed type reactor can be considered. Any of these methods can be applied.

When the reaction is carried out in a fixed bed flow type reactor, the reaction pressure may be any of reduced pressure, normal pressure and increased pressure, but it is preferably normal pressure to 7 Kg / cm ² . The reaction temperature is 300 to 700 ° C, preferably 400 to 600 ° C. Examples of the reaction atmosphere include an inert gas atmosphere such as nitrogen, a hydrogen atmosphere, or a mixed atmosphere thereof. Liquid hourly space velocity is WHSV = 0.01-15.0h ^-1
It is preferably 0.1 to 5.0 h ^-1 . In addition, since 2,6-dimethylnaphthalene produced is a compound having a melting point of 112 ° C., 2-methyl-1- (p-tolyl) -butane, which is a raw material, or 2-
Methyl-1- (p-tolyl) -butene was previously added to benzene,
It is desirable that the reaction be carried out by dissolving in a solvent such as toluene or xylene.

[0017]

The present invention will be described in more detail with reference to the following examples, but the present invention is not limited to these examples.

[0018]

Example 1 (1) Preparation of catalyst A 28.8 g of sodium hydroxide and 4.2 g of sodium carbonate
240 ml of an aqueous solution of magnesium nitrate 102.6
and 480 ml of an aqueous solution of 32.0 g of chromium nitrate were added dropwise over 50 minutes while stirring at room temperature. 65 ℃ after dropping
The temperature was raised to 0, and stirring was continued for 7 hours to cause a reaction. After the reaction, the temperature was lowered, and the generated solid content was filtered. The solid content was washed several times with distilled water and dried at 125 ° C. for 8 hours. This compound was analyzed and identified by X-ray diffraction. The solid obtained is 55
It was calcined in air at 0 ° C. for 18 hours, and this was designated as catalyst A.

(2) 2-methyl-1- (p-tolyl)-
Butane cyclization dehydrogenation reaction A fixed bed flow reactor was charged with 2.0 g of catalyst A aligned in 14/32 mesh, and the catalyst layer was kept at 550 ° C for a pretreatment in a nitrogen stream for 2 hours. 2-methyl-1- (p-
Tolyl) -butane was dissolved in benzene to prepare a 10% by weight solution, and this solution was vaporized at a rate of 2 g / hour through a preheating layer and supplied to the catalyst layer together with 30 cc / min of nitrogen gas at a reaction temperature of 530 ° C. The cyclodehydrogenation reaction was carried out under the condition of a pressure of 1 kg / cm ² . Table 1 shows the reaction results.

[0020]

Example 2 (1) Preparation of Catalyst B 52.0 g of sodium hydroxide and 5.3 g of sodium carbonate
240 mg of aqueous solution of magnesium nitrate 128.2
and an aqueous solution of 40.4 g of iron nitrate in 600 ml were added dropwise over 60 minutes while stirring at room temperature. After the dropping, the temperature was raised to 65 ° C., and stirring was continued for 7 hours to cause a reaction. After the reaction, the temperature was lowered, and the generated solid content was filtered. The solid content was washed several times with distilled water and dried at 125 ° C. for 8 hours. This compound was analyzed and identified by X-ray diffraction. The solid obtained is 530
It was calcined in air at 18 ° C. for 18 hours, and this was designated as catalyst B.

(2) 2-Methyl-1- (p-tolyl)-
Butane cyclization dehydrogenation reaction Using 2.0 g of catalyst B, setting the reaction temperature to 500 ° C.,

The same reaction as in Example 1 was performed. Table 1 shows the reaction results.

[0022]

[Reference example]

(1) Preparation of catalyst C 52.0 g of sodium hydroxide and 5.3 g of sodium carbonate
240 mg of aqueous solution of magnesium nitrate 128.2
600 g of aluminum nitrate and 37.5 g of aluminum nitrate were added dropwise over 60 minutes while stirring at room temperature. After the dropping, the temperature was raised to 65 ° C., and stirring was continued for 18 hours as it was to react. After the reaction, the temperature was lowered, and the generated solid content was filtered. The solid content was washed several times with distilled water and dried at 125 ° C. for 12 hours. This compound was analyzed and identified by X-ray diffraction. The obtained solid was calcined in air at 530 ° C. for 18 hours, and this was designated as catalyst C.

(2) Preparation of Metallic Aqueous Solution Aqueous platinum solution Tetraammineplatinum chloride 171 mg was added to distilled water 50
It was dissolved in ml to prepare an aqueous solution having a platinum weight concentration of 2 mg / ml.

Aqueous palladium solution 231 mg of tetraammine palladium chloride was dissolved in 50 ml of distilled water to give a palladium weight concentration of 2 mg /
An aqueous solution having a volume of ml was prepared.

Aqueous tin solution 190 mg of stannous chloride was dissolved in 50 ml of 5% ammonia water to prepare an aqueous solution having a tin concentration of 2 mg / ml.

[0026]

Example 3 (1) Preparation of catalyst D 2.0 g of catalyst C was added to 100 ml of distilled water, and 7.5 ml of platinum aqueous solution and 7.5 m of tin aqueous solution were added with slow stirring.
1 was added dropwise, and was immersed and impregnated. After this, dry and 550 ℃
It was fired in air. This is designated as catalyst D carrying 0.75% by weight of platinum and 0.75% by weight of tin.

(2) 2-methyl-1- (p-tolyl)-
Cyclodehydrogenation of butane Catalyst D2.0 g was charged in a fixed bed flow reactor, and the catalyst layer was kept at 530 ° C. for reduction treatment in a hydrogen stream for 2 hours. 2-Methyl-1- (p-tolyl) -butane was dissolved in para-xylene to prepare a 5 wt% solution, and this solution was vaporized at a rate of 2 g / hour through a preheating layer, and nitrogen gas was 30 cc.
/ Min and supplied to the catalyst layer to carry out the cyclization dehydrogenation reaction under the conditions of a reaction temperature of 530 ° C. and a reaction pressure of 1 kg / cm ² .
The reaction results are shown in Table 3.

[0028]

Example 4 (1) Preparation of Catalyst E 2.0 g of catalyst C was added to 100 ml of distilled water, and 15.0 ml of an aqueous palladium solution and 15.0 ml of a tin aqueous solution were added dropwise and impregnated with the solution while slowly stirring. After that, it was dried and air-baked at 550 ° C. This is referred to as catalyst E in which 1.50% by weight of palladium and 1.50% by weight of tin are supported.

(2) 2-Methyl-1- (p-tolyl)-
Cyclodehydrogenation of butane Using 2.0 g of catalyst E,

Example 3 A similar reaction was performed. The reaction results are shown in Table 3.

[0030]

Example 5 (1) Preparation of catalyst F 2.0 g of catalyst C was added to 100 ml of distilled water, and 15.0 ml of platinum aqueous solution and 1 tin aqueous solution were added with slow stirring.
5.0 ml was dripped and immersed and impregnated. After this, dry
Air-baked at 550 ° C. This is designated as catalyst F carrying 1.50% by weight of platinum and 1.50% by weight of tin.

(2) 2-methyl-1- (p-tolyl)-
Cyclodehydrogenation of butane Using 2.0 g of catalyst F

Example 3 A similar reaction was performed. The reaction results are shown in Table 3.

[0032]

Example 6 (1) Preparation of catalyst G 2.0 g of catalyst C was added to 100 ml of distilled water, and 2.5 ml of an aqueous palladium solution and 2.5 ml of an aqueous tin solution were added dropwise and impregnated with the solution while slowly stirring. After this, dry
Air-baked at 550 ° C. Palladium is 0.2
The catalyst G was loaded with 5 wt% and 0.25 wt% of tin.

(2) 2-Methyl-1- (p-tolyl)-
Cyclodehydrogenation of butane Using 2.0 g of catalyst G, 2-methyl-1-
(P-Tolyl) -butane was dissolved in benzene to prepare a 10% by weight solution,

Example 3 A similar reaction was performed. The reaction results are shown in Table 3.

[0034]

Example 7 (1) Preparation of catalyst H To 100 ml of distilled water, 2.0 g of catalyst C was added, and 5.0 ml of a platinum aqueous solution was added dropwise and impregnated while slowly stirring. After that, it was dried and air-baked at 550 ° C. This is referred to as a catalyst H in which 0.50% by weight of platinum is supported.

(2) 2-methyl-1- (p-tolyl)-
Cyclodehydrogenation reaction of butane Using 2.0 g of catalyst H, 2-methyl-1-
(P-Tolyl) -butane was dissolved in benzene to prepare a 10 wt% solution at a reaction temperature of 500 ° C.

Example 3 A similar reaction was performed. The reaction results are shown in Table 3.

[0036]

Example 8 (1) Preparation of catalyst I To 100 ml of distilled water, 2.0 g of catalyst C was added, and 5.0 ml of an aqueous palladium solution was added dropwise and impregnated while slowly stirring. After that, it was dried and air-baked at 550 ° C. This is designated as catalyst I on which 0.50% by weight of palladium was supported.

(2) 2-Methyl-1- (p-tolyl)-
Cyclodehydrogenation of butane Using 2.0 g of catalyst I,

The same reaction as in Example 7 was performed. The reaction results are shown in Table 3.

[0038]

Example 9 (1) Preparation of Catalyst J 0.60 g of lithium nitrate was dissolved in 50 ml of distilled water,
2.0 g of catalyst C, which was previously immersed in 100 ml of distilled water
In addition, it was immersed and impregnated. After that, it was dried and air-baked at 550 ° C. This is designated as catalyst J in which lithium was supported by 3.0% by weight.

(2) 2-methyl-1- (p-tolyl)-
Cyclodehydrogenation of butane Using 2.0 g of catalyst J

The same reaction as in Example 1 was performed. The reaction results are shown in Table 3.

[0040]

Example 10 (1) Cyclodehydrogenation of 2-methyl-1- (p-tolyl) -butene A fixed bed flow reactor was charged with 2.0 g of catalyst D and the catalyst layer was kept at 530 ° C. in a hydrogen stream. The reduction treatment was carried out for the middle 2 hours.
As a raw material, 2-methyl-1- (p-tolyl) -butene was dissolved in paraxylene to prepare a 5% by weight solution,

The same reaction as in Example 1 was performed. The reaction results are shown in Table 3.

[0041]

Comparative Example 1 (1) Preparation of Catalyst K 1.60 g of indium nitrate was dissolved in 400 ml of distilled water, and γ-alumina 10.0 was added to this indium nitrate aqueous solution.
g and soaked for 2 hours. It was evaporated to dryness and calcined in air at 530 ° C. This is designated as catalyst K.

(2) 2-Methyl-1- (p-tolyl)-
Cyclodehydrogenation reaction of butane Catalyst K was prepared in 14/32 mesh, and 2.0 g was charged in a fixed bed flow type reactor at a reaction temperature of 520 ° C.

The same reaction as in Example 1 was performed. The reaction results are shown in Table 2.

[0043]

Comparative Example 2 (1) Preparation of Catalyst L 3.04 g of chromium nitrate was dissolved in 400 ml of distilled water,
10.0 g of γ-alumina was added to this, and it was immersed and impregnated. After that, it was dried and air-baked at 550 ° C. This is designated as catalyst L.

(2) 2-Methyl-1- (p-tolyl)-
Cyclodehydrogenation of butane 2.0g of catalyst L was used, the reaction temperature was 500 ° C,

The same reaction as in Example 1 was performed. The reaction results are shown in Table 2.

[0045]

Comparative Example 3 (1) Preparation of Catalyst M 2.0 g of silica having a particle size of 14/32 mesh was added to 100 ml of distilled water, and the platinum aqueous solution 1
0.0 ml was added dropwise and immersed and impregnated. After this, dry
Air-baked at 550 ° C. This is designated as a catalyst M in which 1.00% by weight of platinum is supported.

(2) 2-Methyl-1- (p-tolyl)-
Cyclodehydrogenation of butane Using a catalyst M of 2.0 g at a reaction temperature of 500 ° C.

The same reaction as in Example 3 was performed. The reaction results are shown in Table 4.

[0047]

According to the method of the present invention, 2-methyl-1- (p-tolyl) -butane, which has hitherto been considered difficult, is used as a main raw material for cyclization dehydrogenation with high conversion and high selectivity. It becomes possible to inexpensively produce 2,6-dimethylnaphthalene, which is a raw material of a useful polymer material.

[0048]

[0049]

[0050]

[Table 3]

[0051]

[Table 4]

Claims (4)

[Claims] 1. A method for producing 2,6-dimethylnaphthalene, which comprises using hydrotalcite when carrying out a cyclodehydrogenation reaction using alkylbenzene or alkenylbenzene as a raw material. 2. When carrying out a cyclodehydrogenation reaction using alkylbenzene or alkenylbenzene as a raw material, it contains at least one element selected from the elements of Group Ia, Group VIII and Group IVb of the Periodic Table, and is used as a carrier. A method for producing 2,6-dimethylnaphthalene, which comprises using hydrotalcite. 3. The group Ia element is lithium, cesium or VIII.
The method for producing 2,6-dimethylnaphthalene according to claim 2, wherein the group element is palladium and platinum, and the group IVb element is tin and germanium. 4. The alkylbenzene is 2-methyl-1-
(P-tolyl) -butane and alkenylbenzene are 2-methyl-1- (p-tolyl) -butene.
A method for producing 2,6-dimethylnaphthalene described in the above.