JPH069477A - Production of naphthaldehyde - Google Patents

Abstract

PURPOSE:To produce naphthaldehyde in high yield by vapor-phase oxidation reaction of methylnaphthalene. CONSTITUTION:Methylnaphthalene is brought into contact with a catalyst of molybdenum oxide or vanadium oxide carried on magnesium oxide or further containing a potassium compound, together with a gas containing oxygen at 250 to 450 deg.C.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for selectively producing naphthaldehyde by a gas phase oxidation reaction using methylnaphthalene as a raw material.

[0002]

2. Description of the Related Art A large amount of methylnaphthalene is contained in a coke oven by-product tar and a high boiling point fraction of petroleum. However, since methylnaphthalene has no utility value at present, development of an effective utilization method thereof is strongly desired.

Further, there have been very few reports on the gas phase oxidation technology of methylnaphthalene, but the gas phase oxidation has advantages such as easy separation of products and continuous operation as compared with liquid phase oxidation. It would be industrially very effective if the application development of methylnaphthalene using gas phase oxidation could be possible.

Past studies on the production of naphthaldehyde by gas phase oxidation reaction using methylnaphthalene as a raw material (C.
A. , 135736 (1974)), the selectivity of naphthaldehyde was as low as about 35%.

The present invention has been made in view of the above point, and selectively produces naphthaldehyde, which is important as an intermediate when synthesizing various chemical products, by using methylnaphthalene as a raw material by a gas phase oxidation reaction. It provides a method that can be done.

[0006]

It is an object of the present invention to develop a method for producing naphthaldehyde with high efficiency by subjecting methylnaphthalene to gas phase oxidation.

[0007]

The present invention is characterized in that methylnaphthalene is brought into contact with a catalyst in which molybdenum oxide or vanadium oxide is supported on magnesium oxide at 250 ° C. to 450 ° C. together with an oxygen-containing gas. This is a selective production method of naphthaldehyde.

The catalyst used in the present invention is characterized in that magnesium oxide is used as a carrier, whereby naphthaldehyde can be selectively obtained. By including a potassium compound as a catalyst component, it is possible to improve stability against deterioration of catalytic performance and selectivity of naphthaldehyde.

Magnesium, vanadium and molybdenum, which are the catalyst components in the present invention, need only be in the form of oxides after catalyst preparation, and the catalyst constituent raw materials include nitrates, hydrochlorides, organic acid salts and the like of each metal. Can be used. As the potassium compound, various potassium salts can be used, but nitrates are particularly preferable.

The catalyst can be prepared by a known impregnation method, coprecipitation method, precipitation method or the like.

The methylnaphthalene used as a raw material in the method of the present invention does not have to have a high purity, and a large amount of by-product tar or a high boiling point component of petroleum produced during the coke production process can be used. The oxidizing agent may be any gas containing oxygen, and air can be usually used.

The method for producing naphthaldehyde of the present invention comprises:
Either a fluidized bed or a fixed bed can be used.
The particle size and shape of the catalyst can be arbitrarily selected according to the type of reactor.

The reaction temperature in the method of the present invention is 2
The range of 50 ° C to 450 ° C is preferable. Reaction temperature is 250
This is because if the temperature is lower than 0 ° C, a sufficient conversion cannot be obtained, and if the temperature exceeds 450 ° C, the amount of decomposition gas such as CO and CO ₂ is increased.

[0014]

EXAMPLES The present invention will now be described in more detail with reference to examples.

Example 1 Powdered magnesium oxide was mixed with an aqueous solution in which ammonium metavanadate was dissolved, and this was thoroughly stirred.
This is dried in a drier to remove water sufficiently, and then 450
It was calcined in air at ℃ for 3 hours. The composition of the obtained catalyst was such that V ₂ O _{5 was} 5 wt% and the balance was MgO.

Next, 6 g of a catalyst having a particle size adjusted to 20 to 40 mesh was charged into a stainless reaction tube, and a mixed gas of 2-methylnaphthalene: air: water: He = 1: 12: 16: 5 (molar ratio). At a flow rate of 152 Nml / min at 400 ° C
Contacted at a temperature of. The reaction liquid and gas thus obtained were sequentially sampled and analyzed mainly by gas chromatography, and the conversion and the selectivity of 2-naphthaldehyde were as shown in Table 1 below.

[0017]

[Table 1]

Example 2 Using 6 g of the catalyst prepared in the same manner as in Example 1 by using ammonium molybdate in place of ammonium metavanadate, the reaction was carried out under the same reaction conditions as in Example 1, and The results are also shown in Table 1.

Examples 3 and 4 Potassium nitrate was added during the preparation of the catalyst, and 6 g of the catalyst prepared in the same manner as in Examples 1 and 2 was used to carry out the reaction under the same reaction conditions as in Example 1, and the following first The results also shown in the table were obtained.

Comparative Examples 1 to 9 In place of magnesium oxide, the carriers shown in Table 2 below were used, and ammonium metavanadate or ammonium molybdate and potassium nitrate were used in Examples 3, 4
When 6 g of the catalyst prepared by the same method as above was used and the reaction was carried out under the same reaction conditions as in Example 1, the results shown in Table 2 below were also obtained.

[0021]

[Table 2]

Examples 5-10 Examples 3 and 4 were carried out by changing the contents of vanadium oxide, molybdenum oxide, magnesium oxide and potassium in the catalyst.
When a reaction was performed under the same reaction conditions as in Example 1 using a catalyst prepared by the same method as in Example 1, the results shown in Table 3 below were obtained.

[0023]

[Table 3]

Example 11 MoO ₃ (10) · K ₂ O prepared in the same manner as in Example 4
(10) 25 g of MgO (80) catalyst was charged into a reaction tube, and 2-methylnaphthalene: air: water: He = 1: 4.
A mixed gas of 0: 4: 62 (molar ratio) with a flow rate of 504 Nml
/ Min at a temperature of 340 ° C. As a result, the conversion rate was 22.1% and the 2-naphthaldehyde selectivity was 7
It was 8.4%.

Example 12 A reaction tube was charged with 50 g of the same catalyst as used in Example 11, and 2-methylnaphthalene: air: water: He = 1: 8.
The flow rate of the mixed gas of 0: 0: 133 (molar ratio) is 254 Nm.
Contact was performed at a temperature of 340 ° C. at 1 / min. As a result, the conversion was 37.4% and the 2-naphthaldehyde selectivity was 73.3%.

Example 13 A reaction tube was charged with 50 g of the same catalyst as used in Example 11, and 1-methylnaphthalene: air: water: He = 1: 8.
The flow rate of the mixed gas of 0: 0: 133 (molar ratio) is 254 Nm.
Contact was performed at a temperature of 340 ° C. at 1 / min. As a result, the conversion rate was 47.2% and the 1-naphthaldehyde selectivity was 71.1%.

[0027]

As described above, according to the method for producing naphthaldehyde of the present invention, naphthaldehyde can be easily obtained with a high selectivity by the gas phase oxidation reaction using methylnaphthalene as a raw material. .

Claims (2)

[Claims] 1. A method for producing naphthaldehyde, which comprises contacting methylnaphthalene together with an oxygen-containing gas with a catalyst in which molybdenum oxide or vanadium oxide is supported on magnesium oxide at 250 ° C. to 450 ° C. 2. The method for producing naphthaldehyde according to claim 1, wherein the catalyst contains a potassium compound.