JPH06116189A - Production of 2,3,6-trimethylphenol - Google Patents

Abstract

PURPOSE:To produce 2,3,6-trimethylphenol in high efficiency by subjecting m- cresol and methanol to vapor-phase catalytic reaction in the presence of a catalyst containing oxide of iron or iron and vanadium. CONSTITUTION:2,3,6-Trimethylphdnol is produced by the vapor-phase catalytic reaction of m-cresol with methanol in the presence of a catalyst containing oxide of iron or iron and vanadium. The reaction is carried out in the presence of 2-20mol of methanol and 0.5-16mol of steam based on 1mol of m-cresol.

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 2,3,6-trimethylphenol useful as a synthetic intermediate for 2,3,6-trimethylhydroquinone which is a raw material for vitamin E.

[0002]

2. Description of the Related Art Up to now, as a method for producing 2,3,6-trimethylphenol, metacresol and methanol, 2,6-xylenol and methanol, 2,4,6-
A method using trimethylphenol as a raw material is known. As a method of using meta-cresol and methanol as raw materials, for example, JP-B-52-46929, JP-A-50-76033, and JP-A-56-110637.
JP-B, JP-B-51-11101, JP-B-52-
Japanese Patent No. 12692 is known.

However, according to these methods, due to the influence of the catalyst composition and the reaction conditions, there are many phenol by-products and the decomposition reaction of methanol is vigorous, so that it is an advantageous method for producing 2,3,6-trimethylphenol. I can not say.

[0004]

SUMMARY OF THE INVENTION An object of the present invention is to provide a method for producing 2,3,6-trimethylphenol which produces less phenol by-products and less decomposes methanol. is there.

[0005]

DISCLOSURE OF THE INVENTION The present inventors have found that the generation of by-products is small and the decomposition of methanol is small.
-As a result of intensive studies to develop a method for producing trimethylphenol, when a gas-phase catalytic reaction is carried out in the presence of a catalyst containing iron or an oxide of iron and vanadium, a certain amount with respect to metacresol. It was found that it is desirable to carry out the reaction with the above methanol and to add a specific amount of steam, and the present invention has been accomplished.

That is, according to the method of the present invention, when the metacresol and methanol are subjected to a gas phase catalytic reaction in the presence of a catalyst containing iron or an oxide of iron and vanadium, 1 mol of the metacresol is added to the reaction system. On the other hand, 2 to 20 mol of methanol and 0.5 to 16 mol of water vapor are allowed to be present to produce 2,3,6-trimethylphenol.

There are various valence oxides of vanadium and iron, but any valence oxide may be used. In the case of vanadium, for example, V ₂ O ₅ , V ₂ O ₄ , V ₂
O ₃ , VO, etc. are good, and in the case of iron, Fe ₂ O ₃ ,
Fe ₃ O ₄ and FeO are preferable. The catalyst can be made by various preparation methods. As a vanadium source, its oxide, ammonium salt, chloride, oxychloride, etc., and as an iron source, its oxide, nitrate, chloride, sulfate, oxalate, etc. It can be prepared by any method such as a precipitation method.

When the catalyst contains both iron and vanadium, the iron atom is preferably in the range of 9 to 1/9 with respect to 1 atom of vanadium. The catalyst is alumina, silica, silica.
It can be used with a suitable carrier such as alumina or diatomaceous earth, or can be used without a carrier. The molar ratio of methanol to meta-cresol in the feedstock is 2 to 2
A value between 0 is suitable. Particularly preferably, it is between 3 and 12. When the molar ratio of methanol to metacresol becomes small, the reaction rate of metacresol becomes low. Further, when it becomes large, the decomposition of methanol proceeds, and the generation of by-product gas extremely increases.

A suitable molar ratio of water vapor to meta-cresol in the feed is between 0.5 and 16. Particularly preferably, it is between 3 and 16. When the molar ratio of water vapor to meta-cresol becomes small, the partial pressure of methanol increases and the decomposition proceeds, so that the generation of by-product gas increases. In addition, the rate of deterioration of catalyst activity over time due to carbonaceous deposition also becomes large. When the molar ratio of water vapor becomes large, not only the partial pressure of meta-cresol is lowered and the space-time yield of 2,3,6-trimethylphenol is lowered, but also a negative point such as an increase in reactor capacity occurs.

The reaction temperature is in the range of 250 to 550 ° C, preferably 300 to 400 ° C. At 250 ° C or lower, the reaction rate of metacresol is low, and at 550 ° C or higher, many compounds methylated except for the ortho position are produced as by-products, and many useless decompositions of methanol also occur. The use of the catalyst of the present invention enables the reaction at a considerably low temperature of 300 to 400 ° C., as compared with the conventionally known method using a magnesium oxide / iron oxide-based or manganese oxide-based catalyst.

The reaction pressure may be normal pressure, reduced pressure, or increased pressure. The contact time between the gas and the catalyst is 0.5 to 50 seconds,
Preferably 1 to 20 seconds is suitable. In the method of the present invention, nitrogen, hydrogen, carbon monoxide, carbon dioxide, methane and the like may coexist in addition to metacresol, a raw material for methanol, and steam to be added, but coexistence is not essential.

The types of reactors applicable to the method of the present invention include fixed beds, moving beds, fluidized beds and the like.

[0013]

The present invention will be described in more detail with reference to the following examples. The metacresol conversion rate and selectivity in the examples are defined by the following formulas (1), (2), and (3).

[0014]

[Equation 1]

[0015]

[Equation 2]

(Phenol means 2,3-xylenol, 2,5-xylenol, 2,3,6-trimethylphenol, etc.)

[0017]

[Equation 3]

[0018]

Example 1 A gas phase catalytic reaction was carried out in a fluidized bed reactor using a catalyst in which iron oxide and vanadium oxide were supported on metacresol and methanol on silica. As a catalyst, ammonium metavanadate (NH ₄ VO ₃ ) was dissolved in pure water heated to 90 ° C., and ferric nitrate (Fe (NO
_{3) 3} · 9H adding silica sol (manufactured by Nissan Chemical Snowtex N (TM)) containing ₂ O) and 30 wt% of SiO _2. A slurry of finely divided suspension material uniformly dispersed in silica sol colloid is obtained. This was dried with a co-current type spray dryer.

The atomization of the raw material slurry can be carried out by any of the industrially used centrifugal system, two-fluid nozzle system and high-pressure nozzle system, but the centrifugal system is particularly preferred. The particle size is 10 to 150 μm, which is suitable for use in a fluidized bed reactor, by controlling the rotation speed of the disk and the supply speed of the slurry in the centrifugal system.
Can be distributed between.

The obtained dry powder was pre-baked at 350 ° C. for 2 hours using a tunnel kiln, and then at 750 ° C. for 3 hours.
Time firing was performed. The prepared catalyst had an atomic ratio of iron to vanadium of 1: 1. 4.5 kg of this catalyst was placed in a fluidized bed reactor having a diameter of 10 cm, and a raw material having a molar ratio of metacresol: methanol: steam of 1: 7: 16 was fed at a feed rate of metacresol of 0 per unit catalyst weight of 1 kg. The reaction was carried out by supplying it so that the amount became 0.07 kg.

The reaction temperature is 320 ° C., 330 ° C., 340
C., 350.degree. C., 360.degree. 48 reactions each
It went on continuously for hours. The total amount of gas flowing out of the reactor was passed through a condenser, and the condensed liquid was analyzed by gas chromatography.

The results are shown in Table 1.

[0023]

Example 2 In the same manner as in Example 1, the reaction was carried out at a raw material molar ratio of metacresol: methanol: steam of 1: 7: 3. However, the reaction temperature was 1 point of 320 ° C. The results are shown in Table 2.

[0024]

Example 3 In the same manner as in Example 1, the reaction was carried out at a raw material molar ratio of metacresol: methanol: steam of 1: 7: 10. The results are shown in Table 3.

[0025]

Example 4 In the same manner as in Example 1, the reaction was carried out at a raw material molar ratio of metacresol: methanol: steam of 1: 12: 3. The results are shown in Table 4.

[0026]

Example 5 In the same manner as in Example 1, the reaction was carried out at a raw material molar ratio of metacresol: methanol: steam of 1: 20: 3. However, the reaction temperature is 295 ° C, 310
C., 330.degree. C., 350.degree. C., 360.degree. C., 370.degree.

The results are shown in Table 5.

[0028]

Example 6 When the catalyst was prepared, the compounding ratio of iron and vanadium was changed so that the atomic ratio of iron and vanadium was 1: 9, 1:
Five kinds of catalysts of 2, 1: 1, 2: 1, and 9: 1 were prepared. 10 g of this catalyst was put into a Pyrex fixed bed reactor having a diameter of 18 mm, and a raw material having a molar ratio of metacresol: methanol: steam of 1: 7: 16 was used as a unit catalyst weight of 1 g.
Was fed and reacted so that the feed amount of meta-cresol per hour was 0.07 g.

The reaction temperatures are 310 ° C., 320 ° C., and 3 ° C., respectively.
Three points at 50 ° C. were performed. Each reaction was continuously performed for 48 hours. The total amount of gas flowing out of the reactor was passed through a condenser, and the condensed liquid was analyzed by gas chromatography. The results are shown in Table 6.

[0030]

[Table 1]

[0031]

[Table 2]

[0032]

[Table 3]

[0033]

[Table 4]

[0034]

[Table 5]

[0035]

[Table 6]

[0036]

INDUSTRIAL APPLICABILITY The method of the present invention produces less phenol by-products and less decomposes methanol.
It is useful as a method for producing 6-trimethylphenol.

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Claims (1)

[Claims] 1. Metacresol and methanol in the presence of a catalyst containing iron or an oxide of iron and vanadium,
When the gas-phase catalytic reaction is carried out, 0.5 to 20 mol of methanol and 2 to 20 mol of methanol are added to the reaction system.
2, characterized by the presence of 16 moles of water vapor
A method for producing 3,6-trimethylphenol.