JPH09241237A - Method for producing ε-caprolactam - Google Patents

Abstract

(57) Abstract: The present invention relates to a method for producing ε-caprolactam from cyclohexanone oxime by a gas phase reaction, using a zeolite that is easy to produce and has a large pore size, and has a high conversion rate and a high selectivity. With the object of providing a method capable of producing ε-caprolactam, the presence of a solvent that does not increase the loss during recovery and circulation,
It is an object of the present invention to provide a method capable of producing ε-caprolactam with high conversion and high selectivity. An object of the present invention is to provide a method for producing ε-caprolactam, which comprises subjecting cyclohexanone oxime to gas phase contact with β-zeolite in the presence of alcohol, particularly in the presence of alcohol having 5 to 10 carbon atoms. To be achieved.

Description

Detailed Description of the Invention

[0001]

[0001] The present invention relates to a process for producing ε-caprolactam, which is very useful as a raw material for nylon, from cyclohexanone oxime by a gas phase reaction.

[0002]

2. Description of the Related Art As a method for producing ε-caprolactam from cyclohexanone oxime by a gas phase reaction (gas phase Beckmann rearrangement reaction), a method of contacting cyclohexanone oxime with a solid acid catalyst in a gas phase is known. Examples of this catalyst include boric acid catalysts (Japanese Patent Publication No. 47-4).
1909), phosphoric acid-based catalyst (Japanese Patent Publication No. 45-2)
3549), silica-alumina-based catalyst (Japanese Patent Publication No. 48)
-39952), zeolite-based catalysts (JP-A-57-139062, JP-A-62-123167).
JP-A No. 2-275850).

However, boric acid-based and phosphoric acid-based catalysts have a problem that the catalyst deteriorates due to volatilization of active components during the reaction, and silica-alumina-based catalysts have a problem that the selectivity is not sufficiently high.

In the method using a zeolite-based catalyst, a zeolite (ZSM-based zeolite) having a silica-to-alumina ratio of at least 12 and a constraint index of 1 to 12 described in JP-A-57-139062, and 62-1
The control index described in Japanese Patent No. 23167 is 1 to 12,
Si / Al atomic ratio is 500 or more and extra-pore acid amount is 5μ
A crystalline zeolite having an equivalent weight / g or less (ZSM-based zeolite, silicalite-based zeolite, etc.) is used as a catalyst.

However, a crystalline zeolite (Si having a silica-to-alumina ratio of 12 or more and a constraint index of 1 to 12).
When the gas phase Beckmann rearrangement reaction was actually carried out using the / Al atomic ratio of 500 or less), satisfactory results could not be obtained with respect to the activity and selectivity of the catalyst, and the catalytic activity was substantially effective in the reaction for several hours. It has been found that

On the other hand, the control index is 1 to 12, and Si
When a crystalline zeolite having an / Al atomic ratio of 500 or more and an extracellular acid amount of 5 μeq / g or less is used, both activity and selectivity are higher than those of the above-mentioned zeolite having a small Si / Al atomic ratio. Although the activity is high and the activity tends not to decrease, there are problems in production of this type of zeolite. That is, in order to produce a crystalline zeolite with a low Al content, it is necessary to use a high-purity raw material with a low impurity Al content as a Si source, and when such a zeolite is industrially produced. Is A from sources other than Si source
There is a problem that industrial production is not easy, for example, mixing of impurities such as 1 must be prevented. Furthermore, in order to reduce the amount of acid outside the pores of the zeolite, it is necessary to carry out an operation such as surface modification with an organometallic compound, which complicates the production process.

Further, ZSM type zeolite has 5.3Å ×
It has pores with a size of 5.6 Å, but the pore diameter is about the same as the molecular diameter of the starting material cyclohexanone oxime, and smaller than the molecular diameter of the product ε-caprolactam. For this reason, the diffusion of the raw materials and products in the pores is delayed, which is a disadvantage of this type of zeolite. In order to overcome this, it is necessary to reduce the particle size of the catalyst, but ZSM-based zeolite has a problem that its industrial production becomes difficult.

On the other hand, in JP-A-2-275850, in producing ε-caprolactam from cyclohexanone oxime under a gas phase reaction condition using a solid acid, a lower alcohol having 6 or less carbon atoms should be present in the reaction system. Discloses a method for producing ε-caprolactam with a high selectivity even under the condition that the conversion rate (reaction rate) of cyclohexanone oxime is high. However, in this method, the effect is substantially observed when an alcohol having 3 or less carbon atoms, particularly methanol or ethanol is used,
For example, when 1-hexanol having 6 carbon atoms is used, the conversion rate of cyclohexanone oxime becomes extremely low,
The selectivity of ε-caprolactam is also decreasing. When alcohols such as methanol and ethanol are used, there is a problem that these alcohols have large boiling points because of their low boiling points, and industrially there is a large loss in recovery and circulation.

[0009]

SUMMARY OF THE INVENTION Under such circumstances,
Using a zeolite that is easy to manufacture and has a large pore size,
There has been a demand for a method capable of producing ε-caprolactam from cyclohexanone oxime with a high conversion rate and a high selectivity by a gas phase reaction in the presence of a solvent that does not cause a large loss during recovery or circulation. The present invention is a method for producing ε-caprolactam from cyclohexanone oxime by a gas phase reaction, using a zeolite having a large pore size, which is easy to produce, and a method capable of producing ε-caprolactam with high conversion and high selectivity. It is an object of the present invention to provide a method capable of producing ε-caprolactam with a high conversion and a high selectivity in the presence of a solvent that does not cause a large loss during recovery and circulation. is there.

[0010]

The object of the present invention is characterized in that cyclohexanone oxime is brought into gas phase contact with β-zeolite in the presence of alcohol, particularly in the presence of alcohol having 5 to 10 carbon atoms. This is achieved by the method for producing caprolactam.

[0011]

BEST MODE FOR CARRYING OUT THE INVENTION β used as a catalyst in the present invention
Type zeolites are, for example, zeolites produced by the method described in US Pat. No. 3,308,069. This β-type zeolite has pores with a size of 5.7 Å × 7.5 Å, and its control index is as small as 0.6.

The β-type zeolite is produced by mixing a Si source, an Al source and an organic ammonium salt as a crystallization modifier, adjusting the pH with an appropriate base or acid, and then performing hydrothermal synthesis. Since β-zeolite after hydrothermal synthesis contains organic ammonium salt and metal cations such as Na ⁺ and K ⁺ , the zeolite is calcined in air to decompose and remove the organic ammonium salt, and then ammonium nitrate is added. It is preferable to use by converting to H ⁺ type by removing ions such as Na ⁺ and K ⁺ by performing ion exchange with water or dilute hydrochloric acid and then firing.

As the Si source, ethyl silicate, sodium silicate, colloidal silica or the like is used, and as the Al source, sodium aluminate, colloidal aluminum or the like is used, but it is not particularly limited. As the organic ammonium salt, tetraethylammonium chloride, tetraethylammonium bromide, tetraethylammonium hydroxide, etc. are used.

The Si / Al atomic ratio of β-type zeolite is usually 1 or more. The outer surface area of the pores is not particularly limited. The size of the β-zeolite is not particularly limited as long as it can be used in a fixed bed or a fluidized bed, whether it is a powder, a pulverized product, or a product molded to a certain size. .

Next, a method for producing ε-caprolactam by a gas phase reaction will be described. The reaction is a conventional fixed bed or fluidized bed reactor (reaction tube) filled with the catalyst.
The cyclohexanone oxime vaporized in the raw material vaporizer while supplying alcohol to the
V) 0.01 to 100 hr ^-1 , preferably ¹ to 10 hr
^This is done by feeding at ^-1 . The reaction temperature is preferably 200 to 500 ° C, particularly preferably 300 to 400 ° C. Alcohol is 0.01 to 100 times by weight, especially 0.1 to 100 times by weight cyclohexanone oxime.
It is preferably used 10 times by weight.

Cyclohexanone oxime and alcohol are individually introduced into the raw material vaporizer, or are introduced into the raw material vaporizer as a mixture of both. The vaporized cyclohexanone oxime and alcohol are usually introduced into the reactor together with a carrier gas that does not adversely affect the reaction. As the carrier gas, for example, nitrogen gas,
Carbon dioxide gas and hydrogen gas can be mentioned. The amount of carrier gas is not particularly limited as long as cyclohexanone oxime and alcohol are supplied within the above weight hourly space velocity (WHSV) range.

As the alcohol, an aliphatic alcohol such as methanol, ethanol, 1-propanol, 2-propanol, 1-butanol, 2-butanol, 1-pentanol, 1-hexanol, 1-heptanol or 1-octanol, Preferred is an aliphatic alcohol having 1 to 10 carbon atoms. Among these alcohols, aliphatic alcohols having 5 or more carbon atoms (that is, 5 to 10), and further 5 to 8 have a small recovery / circulation loss, and have a higher conversion rate and a higher selectivity to produce ε-caprolactam. It is preferable because it can be produced.

The produced ε-caprolactam is purified by separating the alcohol, unreacted raw materials and by-products by distillation or recrystallization after cooling and condensing the reaction gas discharged from the reactor (reaction tube). To be done. Alcohol, particularly alcohol having 5 or more carbon atoms, is recovered with little loss and circulated / supplied to the reaction system.

[0019]

Next, the present invention will be described specifically with reference to examples and comparative examples. Example 1 In a reaction tube made of stainless steel having a length of 55 cm and an inner diameter of 0.7 mm, the Si / Al atomic ratio was 12.8 (Si / Al ₂ = 2.
5.6) H ⁺ type β type zeolite (manufactured by Tosoh Corporation) 20
1 ml (0.8 g) crushed to ˜30 mesh was filled and heated in a nitrogen gas stream at 400 ° C. for 30 minutes. Then, under normal pressure, with nitrogen gas (24 ml / min),
Methanol containing 10 mol% of cyclohexanone oxime was supplied through a vaporizer (cyclohexanone oxime: methanol: nitrogen (molar ratio) = 1: 9: 10), 3
The reaction was carried out at 50 ° C. Cyclohexanone oxime was supplied at WHSV = 0.83 hr ^-1 . The condensate obtained by cooling the reaction gas discharged from the reaction tube with ice was analyzed by gas chromatography every hour. As a result, at the 4th hour after the reaction, the conversion of cyclohexanone oxime was 80.6 mol% and the selectivity of ε-caprolactam (ratio in the product) was 86.9 mol%.

Examples 2 to 6 Reactions and analyzes were conducted in the same manner as in Example 1 except that methanol was replaced with alcohol shown in Table 1 and the reaction time was changed to that shown in Table 1. Table 1 shows the results.

Comparative Example 1 Reaction and analysis were carried out in the same manner as in Example 1 except that benzene was used instead of alcohol in Example 1. as a result,
Cyclohexanone oxime conversion was 9 after 4 hours of reaction.
At 8.8 mol%, the selectivity of ε-caprolactam is 73.
It was 0%. The results are shown in Table 1.

[0022]

[Table 1]

Example 7 The reaction and analysis were performed in the same manner as in Example 1 except that 1-pentanol was used instead of methanol in Example 1. Table 2 shows the results.

[0024]

[Table 2]

Example 8 Reaction and analysis were carried out in the same manner as in Example 1 except that 1-hexanol was used in place of methanol. Table 3 shows the results.

[0026]

[Table 3]

Example 9 Reaction and analysis were carried out in the same manner as in Example 1 except that methanol was replaced with 1-heptanol. The results are shown in Table 4.

[0028]

[Table 4]

[0029]

EFFECTS OF THE INVENTION According to the present invention, β-type zeolite is used to produce cyclohexanone oxime with a high conversion rate and a high selectivity by a gas phase reaction even in the presence of an alcohol having a carbon number of 5 or more, which does not cause a large loss during recovery or circulation. Ε-caprolactam can be produced at a rate. The β-zeolite of the present invention is easier to produce and has a larger pore size than ZSM-type zeolite and the like, and thus is industrially preferable to the method of using the ZSM-type zeolite as a catalyst according to the present invention. It is possible to provide a method for producing ε-caprolactam.

Claims (2)

[Claims] 1. A method for producing ε-caprolactam, which comprises contacting cyclohexanone oxime with β-type zeolite in the gas phase in the presence of alcohol. 2. The method for producing ε-caprolactam according to claim 1, wherein the alcohol is an alcohol having 5 to 10 carbon atoms.