JP3301092B2 - Method for producing ε-caprolactam - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a process for producing ε-caprolactam from cyclohexanone oxime under gas phase reaction conditions using a solid catalyst.

[0002]

2. Description of the Related Art
Caprolactam is an important basic chemical raw material used as a raw material for nylon and the like. Its production method has conventionally used fuming sulfuric acid or concentrated sulfuric acid as a catalyst and rearranges cyclohexanone oxime in a liquid phase (Beckmann rearrangement). The method has been adopted.

[0003] However, this method not only requires a large amount of fuming sulfuric acid but also has a problem that a large amount of ammonium sulfate is by-produced.

On the other hand, in order to solve these problems, the present inventors have proposed a method of rearranging under a gas phase reaction condition using a solid catalyst (JP-A-2-275850 and JP-A-2-250866). No.).

In general, when a solid catalyst is used, the activity of the catalyst is reduced. Therefore, either a method of replacing such a deteriorated catalyst with a new catalyst or a method of regenerating and reusing the deteriorated catalyst is adopted. Is done.

As a method of regenerating a catalyst, a method of burning and removing a carbonaceous substance deposited on the catalyst in a molecular oxygen-containing gas, for example, air, is generally employed ("Catalyst Engineering Course (No. 7) Catalytic Reaction (2)-Oxidation, Dehydrogenation, Decomposition-"(Showa 42.2.28) Jinjinshokan
278).

The present inventors have proposed a method for regenerating a solid catalyst by burning a carbonaceous substance in the presence of an alcohol in the presence of a molecular oxygen-containing gas (Japanese Patent Laid-Open No. 3-207454). Gazette).

On the other hand, in the decomposition reaction of n-hexane,
Bringing the zeolite catalyst deactivated by thermal damage into contact with water,
Subsequently, a regeneration method in which ion exchange is performed with an ammonium salt such as ammonium nitrate has been proposed (JP-A-61-38).
630). Further, in the conversion reaction of methanol to hydrocarbons has been proposed a method of regenerating by contact with ammonia and steam a zeolite catalyst deactivated at 100 to 1000 ° C. The firing, high SiO ₂ / Al ₂ It has also been shown that zeolite having an O ₃ ratio (26000) is not regenerated (Japanese Patent Laid-Open No.
0-42227, JP-A-60-257838).

Further, in a cracking reaction or a conversion reaction of an alcohol to a hydrocarbon, a regeneration method has been proposed in which a deactivated zeolite catalyst is brought into contact with an aqueous ammonia solution, and it is also shown that a catalyst without an alumina binder was not regenerated. (JP-A-1-99649).

In view of such a situation, the present inventors have:
In producing ε-caprolactam from cyclohexanone oxime under gas phase reaction conditions, as a result of intensive studies to find a more excellent method for regenerating a solid catalyst, the zeolite catalyst with reduced activity was converted to a specific compound called ammonia. It has been found that the contact can bring back the activity of the deteriorated catalyst, and the present invention has been completed.

[0011]

Means for Solving the Problems That is, the present invention provides a process for preparing ε- caprolactam from cyclohexanone oxime by using a zeolite catalyst in a gas phase reaction conditions, contacting the zeolite catalyst activity decreased with ammonia And then using the catalyst in the reaction to provide a process for producing ε-caprolactam.

Hereinafter, the present invention will be described in detail. The catalyst to which the present invention is applied is a zeolite catalyst, although molded only components of its other, Ru include those modified by supported on a carrier or ion-exchange or the like. Among them, crystalline silica, crystalline metallosilicate and the like are preferable.

For example, the crystalline silica used in the present invention is:
It consists essentially of silicon and oxygen.

The crystalline metallosilicate used in the present invention has a Si / Me atomic ratio (where Me is Al,
Ga, Fe, B, Zn, Cr, Be, Co, La, G
e, Ti, Zr, Hf, V, Ni, Sb, Bi, Cu,
One or two or more metal elements selected from Nb and the like) is usually 5 or more, preferably 500 or more. Si
The / Me atomic ratio can be determined by conventional analytical means, for example, atomic absorption spectroscopy,
It can be determined by a fluorescent X-ray method or the like.

The crystalline silica or crystalline metallosilicate used in the present invention is produced by a known method. Various structures are known for these crystalline silicas or crystalline metallosilicates, but those belonging to a so-called pentasil type structure are preferable.

The term "deteriorated catalyst" as used herein refers to a zeolite catalyst whose activity has been reduced by reaction or thermal damage.

In the present invention, before the deteriorated catalyst is brought into contact with ammonia, a carbonaceous substance deposited on the catalyst is burned off in advance in a molecular oxygen-containing gas such as air, or alcohol is added to air. It is preferable that the carbonaceous substance deposited on the catalyst be burned and removed in the presence of the catalyst.

The ammonia used in the present invention includes, for example, gaseous ammonia and an aqueous solution containing ammonia. Examples of the aqueous solution containing ammonia include an aqueous ammonia solution and an aqueous ammonia solution containing ammonium salts such as ammonium chloride, ammonium sulfate, and ammonium nitrate.

When gaseous ammonia is used in the present invention, it may be used together with an inert gas such as nitrogen gas or water vapor.

The supply rate of the gaseous ammonia used in the present invention is not particularly limited, but is usually 1 to 2000 l / hr per kg of the catalyst. The regeneration time at that time varies depending on the degree of deterioration of the catalyst, but is usually about 1 to 100 hours.

The aqueous solution containing ammonia used in the present invention usually has a pH of 9 or more, preferably 10 to 13.

In the present invention, the regeneration method using an aqueous solution containing ammonia is not particularly limited, and any method may be used as long as the entire catalyst can be sufficiently contacted with ammonia in an aqueous solution containing ammonia. A method of filling the deteriorated catalyst, then pouring an aqueous solution containing ammonia into the reaction vessel, and immersing the deteriorated catalyst under stirring in the reaction vessel,
Further, a method of passing an aqueous solution containing ammonia in a state where the deteriorated catalyst is packed in a column may be used.

The time for regeneration with an aqueous solution containing ammonia varies depending on the degree of deterioration of the catalyst.
About 10 hours.

Further, it is also effective to carry out a regeneration treatment with an aqueous solution containing ammonia, followed by washing with an acid such as hydrochloric acid and then washing with water.

The temperature at which the deteriorated catalyst is brought into contact with ammonia is usually 50 to 250 ° C. The temperature for contact with gaseous ammonia is preferably 250 ° C. or less,
The range of -200 ° C is more preferred. The pressure at this time is usually 10 atm or less. The temperature for contact with the aqueous solution containing ammonia is preferably 50 to 200 ° C.,
The range of -150 ° C is more preferable.

Next, a method for producing ε-caprolactam in carrying out the present invention will be described. The present invention is carried out by a conventional fixed-bed or fluidized-bed gas-phase catalytic reaction. The reaction temperature is usually in the range of 250 to 500C. 250
At a temperature below ℃, the reaction rate is not sufficient and the selectivity for ε-caprolactam tends to decrease. 5
When the temperature exceeds 00 ° C., thermal decomposition of cyclohexanone oxime cannot be ignored, and the selectivity for ε-caprolactam tends to decrease. In particular, the preferred temperature range is 300
４５０450 ° C., and the most preferred temperature range is 300〜4
00 ° C. The reaction pressure is not particularly limited, and is usually 0.05 to 10 kg / cm ² .

Space velocity of raw material cyclohexanone oxime
Is usually WHSV = 0.1-40hr ^-1(That is, catalyst 1
The feed rate of cyclohexanone oxime per kg is 0.1
４０40 kg / hr). Preferably 0.2 to 20 hours^-1so
Yes, more preferably 0.5 to 10 hours^-1Select from the range
It is.

Separation of ε-caprolactam from the reaction mixture can be carried out in a conventional manner. For example, the reaction product gas is cooled and condensed, and then ε-caprolactam purified by extraction, distillation or crystallization can be obtained.

[0029]

As described in detail above, according to the present invention,
By using ammonia as the deteriorated catalyst, the activity of the catalyst can be sufficiently recovered and the life of the catalyst can be further improved, so that ε-caprolactam can be efficiently produced.

[0030]

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

Reference Example 1 (Preparation of Catalyst A) 100 g of tetraethylorthosilicate (Si (OC ₂ H ₅ ) ₄ , Al content 10 ppm or less) was placed in a 1.5-liter stainless steel autoclave, and 10% tetra-n-propyl hydroxide was used. An ammonium aqueous solution (224.0 g) and ethanol (214 g) were charged and stirred vigorously for 30 minutes. The pH of the mixed solution is 13
Met. After closing the lid of the autoclave, it was immersed in an oil bath, the internal temperature was maintained at 105 ° C., and the hydrothermal synthesis was performed for 96 hours while stirring at a rotation speed of 400 rpm or more. During this time, the pressure in the autoclave reached 2-3 kg / cm ² . The pH at the end of the hydrothermal synthesis was 11.8. The white solid product was filtered off and washed successively with distilled water until the pH of the filtrate was around 7. The obtained crystals are heated at 120 ° C for 16 hours.
After drying for an hour, the mixture was calcined at 530 ° C. for 4 hours under an air flow to obtain 27 g of powdery white crystals. Powder X
As a result of analysis by line diffraction, it was identified as a pentasil type zeolite. In addition, as a result of elemental analysis by atomic absorption spectroscopy,
The content of Al was 3 ppm.

100 g of a 5% aqueous ammonium chloride solution was added to 10 g of the crystals, subjected to an ion exchange treatment at 50 to 60 ° C. for 1 hour, and then filtered. After four times of this ion exchange treatment, the crystals were washed with distilled water until no Cl ^- ions were detected. The obtained crystals were dried, pressed and sieved to 24-48 mesh. Further, the crystals were calcined at 500 ° C. for 1 hour under flowing nitrogen gas to obtain a catalyst. This catalyst is called catalyst A.

Reference Example 2 (Preparation of catalyst B) A 1.5% stainless steel autoclave was placed in a 10% aqueous solution of tetra-n-propylammonium hydroxide 232.8.
6 g, 62.33 g of ethanol, 50.4 g of distilled water, 2 ml of an aqueous solution containing 0.071 g of titanium tetraisopropoxide, tetraethyl orthosilicate (Si (OC ₂ H ₅ ) ₄ ) 1
04.17 g was charged in this order, and the mixture was sufficiently stirred for 1 hour. Next, the internal temperature was maintained at 105 ° C., and hydrothermal synthesis was performed for 96 hours while stirring at a rotation speed of 400 rpm or more.
The resulting white solid was filtered and washed continuously with distilled water until the pH of the filtrate was around 7. The obtained crystal is
Dry at 16 ° C. for 16 hours. The dried crystals are added for another 5
The mixture was calcined at 30 ° C. for 4 hours under flowing air to obtain 27 g of white powdery crystals. The crystals were analyzed by powder X-ray diffraction. As a result, titanosilicate having a structure similar to that of the pentasil-type zeolite was identified. As a result of atomic absorption analysis of the crystal, the atomic ratio of Si / Ti was 1,900. Less than,
The crystals were ion-exchanged and calcined in the same manner as in Reference Example 1 to obtain a catalyst. This catalyst is referred to as catalyst B.

Reference Example 3 (Preparation of Catalyst C) 100 g of tetraethylorthosilicate (Si (OC ₂ H ₅ ) ₄ ) was placed in a 1.5-liter stainless steel autoclave, and a 22% aqueous solution of tetra-n-propylammonium hydroxide 224.0 was used.
g of ethanol and 60 g of ethanol were sufficiently stirred. An aqueous solution of aluminum sulfate 48 prepared in advance is added to the mixed solution.
g (Al ₂ (SO ₄ ) ₃ .18H ₂ O 3 g / water 48 g),
Stir vigorously for minutes. The pH of the mixed solution was 13. After closing the lid of the autoclave, it was immersed in an oil bath, the internal temperature was kept at 105 ° C., and the hydrothermal synthesis was performed for 120 hours while stirring at a rotation speed of 400 rpm or more. During this time, the pressure in the autoclave reached 2-3 kg / cm ² . The pH at the end of the hydrothermal synthesis was 11.8. A white solid product was obtained in the same manner as in Reference Example 1 to obtain powdery white crystals. The crystal was analyzed by powder X-ray diffraction, and as a result, it was identified as a pentasil-type zeolite. As a result of elemental analysis by atomic absorption spectroscopy, the atomic ratio of Si / Al was 50. Thereafter, the crystals were ion-exchanged and calcined in the same manner as in Reference Example 1 to obtain a catalyst. This catalyst is called catalyst C.

Example 1 (Production of ε-caprolactam) 0.375 of the catalyst A prepared in Reference Example 1 was placed in a quartz glass reaction tube having an inner diameter of 1 cm.
g (0.6 ml) and pre-heated at 350 ° C. for 1 hour under a nitrogen stream (4.2 l / hr). Next, a mixed liquid having a cyclohexanone oxime / methanol weight ratio of 1 / 1.8 was supplied to the reaction tube at a supply rate of 8.4 g / hr to cause a reaction. At this time, the space velocity WHSV was 8 hr ^-1 and the temperature (reaction temperature) of the catalyst layer was 350 ° C. The reaction is 6.
It lasted 25 hours. The reaction product was collected every hour under water cooling and analyzed by gas chromatography.

Here, the space velocity WHSV is calculated by the following equation.
The conversion of cyclohexanone oxime and the selectivity of ε-caprolactam were also calculated by the following equations.

WHSV (hr ⁻ ) = O / C Conversion of cyclohexanone oxime (%) = [(XY) / X] × 100 Selectivity of ε-caprolactam (%) = [Z / (XY) ] × 100 O, C, X, Y and Z are as follows. O = cyclohexanone oxime supply rate (kg / hr) C = catalyst weight (kg) X = mol number of supplied cyclohexanone oxime Y = mol number of unreacted cyclohexanone oxime Z = mol number of ε-caprolactam in the product

After the completion of the reaction, the supply of the methanol solution of cyclohexanone oxime was stopped, and nitrogen gas 2.5 l / hr,
2.5 l / hr of air was mixed and bubbled into methanol kept at 0 ° C., and methanol (3.8% by volume, 0 ° C. saturated concentration) was vaporized and entrained in a mixed gas of nitrogen and air to the reaction tube. Then, the temperature of the catalyst layer was increased to 430 ° C., and the catalyst layer was treated for 23 hours. By this operation, the carbonaceous substance deposited on the catalyst was removed.

Next, the temperature was lowered to 350 ° C. while supplying nitrogen gas (4.2 l / hr). Subsequently, the reaction was carried out under the same reaction conditions as described above.

After the completion of the reaction, the carbonaceous substance deposited on the catalyst was removed by the same operation as described above. Further, the above-described reaction and the operation of removing the carbonaceous substance were repeated 20 times in total. Table 1 shows the results of each reaction.

(Method for Producing ε-Caprolactam of the Present Invention) The autoclave was filled with 0.375 g of the deteriorated catalyst after removing the carbonaceous substance in the twentieth cycle, and 50 ml of a 28% by weight aqueous ammonia solution and 4 g of ammonium chloride were added. And kept at 90 ° C. for 1 hour.

After the holding, the solid separated by filtration was transferred to a flask, 50 ml of 5N hydrochloric acid was added, and the mixture was stirred at 90 ° C. for 1 hour. Next, this solid was filtered, washed with water, and dried. A regenerated catalyst was thus obtained.

0.350 g of the dried catalyst was charged into a quartz glass reaction tube as described above, and the reaction and the operation of removing the carbonaceous substance were repeated as described above. Table 2 shows the reaction results.
Shown in

[0044]

[Table 1]

[0045]

[Table 2]

Example 2 (Method for producing ε-caprolactam) To prepare the catalyst and to confirm the reproducibility of the Beckmann rearrangement reaction of cyclohexanone oxime, a catalyst was prepared again in the same manner as the catalyst A of Reference Example 1 (this catalyst was Hereinafter, it is referred to as Catalyst A *. The content of Al was 3 ppm.)

The same reaction tube as in Example 1 was filled with 0.375 g (0.6 ml) of the catalyst A *, and the Beckmann rearrangement reaction of cyclohexanone oxime and the operation of removing carbonaceous substances were repeatedly carried out in the same manner as in Example 1. did. However, the reaction time was 1 hour, and the operation time for removing the carbonaceous material was 3 hours. Table 3 shows the reaction results.

(Method for Producing ε-Caprolactam of the Present Invention) The deteriorated catalyst from which the carbonaceous material had been removed was taken out of the reaction tube, and the same regeneration method as in Example 1 was performed.

The catalyst subjected to the regeneration treatment was repeatedly subjected to the Beckmann rearrangement reaction of cyclohexanone oxime and the operation of removing the carbonaceous substance in the same manner as described above. Table 4 shows the reaction results.
Shown in

[0050]

[Table 3]

[0051]

[Table 4]

Example 3 (Production method of ε-caprolactam) 0.375 g (0.6 ml) of the catalyst B prepared in Reference Example 2 was charged into the same reaction tube as in Example 1, and the same method as in Example 1 was used. The Beckmann rearrangement reaction of cyclohexanone oxime and the operation of removing the carbonaceous substance were repeatedly performed. Table 5 shows the reaction results.

(Production method of ε-caprolactam of the present invention) After the carbonaceous material was removed, the deteriorated catalyst was taken out of the reaction tube, and 0.375 g of this catalyst was placed in an autoclave, and 50 ml of a 28% by weight aqueous ammonia solution and ammonium chloride were added. 4 g was added and kept at 90 ° C. for 1 hour. After the regeneration treatment, the filtered solid was again put into an autoclave, and the above-mentioned regeneration method was repeated three times.

Next, the solid was filtered, washed with water and dried. 0.350 g of the catalyst thus obtained was charged into the same reaction tube as described above, and the Beckmann rearrangement reaction of cyclohexanone oxime and the operation of removing the carbonaceous substance were repeatedly performed in the same manner as in Example 1. Table 6 shows the reaction results.

[0055]

[Table 5]

[0056]

[Table 6]

Example 4 (Forced degradation treatment and reaction of catalyst by high temperature) Inner diameter 1 cm
Was filled with 0.375 g (0.6 ml) of the catalyst A prepared in Reference Example 1 and nitrogen gas (2.5 l).
/ Hr) is bubbled into distilled water kept at 0 ° C., water (0.6% by volume, 0 ° C. saturated concentration) is vaporized in nitrogen gas, and the mixture is kept at 900 ° C. for 2 hours. ℃)
The temperature was allowed to fall. A Beckmann rearrangement reaction of cyclohexanone oxime was carried out in the same manner as in Example 1 using 0.375 g of the catalyst thus subjected to the forced deterioration treatment. Table 7 shows the reaction results.

Next, the carbonaceous substance deposited on the catalyst was removed by burning in the same manner as in Example 1.

(Method for producing ε-caprolactam of the present invention) 0.375 g of the deteriorated catalyst after removing the carbonaceous material was put in an autoclave, and 50 ml of an aqueous ammonia solution having a pH of 11.5 was added thereto, and the mixture was heated at 90 ° C. For one hour.

After the holding, the solid separated by filtration was put again in the autoclave, and the above treatment was repeated four times. Then the solid was filtered, washed with water and dried.

Using the regenerated catalyst, a Beckmann rearrangement reaction of cyclohexanone oxime was performed in the same manner as described above. Table 8 shows the reaction results.

[0062]

[Table 7]

[0063]

[Table 8]

Example 5 (Forced degradation of catalyst and reaction by high temperature) Example 4
Nitrogen gas in air (2.5 l / hr) at 900 ° C
Except that 2 hours of forced deterioration treatment in
The forced deterioration treatment was performed in the same manner as in Example 4. A Beckmann rearrangement reaction of cyclohexanone oxime was carried out in the same manner as in Example 1 using 0.375 g of the catalyst which had been subjected to the forced deterioration treatment. Table 9 shows the reaction results.

Next, the carbonaceous substance deposited on the catalyst was removed by burning in the same manner as in Example 1.

(Method for Producing ε-Caprolactam of the Present Invention) The deteriorated catalyst from which the carbonaceous material had been removed was subjected to a single regeneration treatment in the same manner as the regeneration method using an aqueous ammonia solution and ammonium chloride shown in Example 3. .

Using the regenerated catalyst, a Beckmann rearrangement reaction of cyclohexanone oxime was carried out in the same manner as described above. Table 10 shows the reaction results.

[0068]

[Table 9]

[0069]

[Table 10]

Example 6 (Production method of ε-caprolactam) 1.0 g (1.6 ml) of the catalyst A * was filled in a quartz glass reaction tube having an inner diameter of 2 cm, and the reaction was carried out under a nitrogen stream (4.2 l / hr). Pre-heat treatment was performed at 350 ° C. for 1 hour. Next, a mixed solution of cyclohexanone oxime / methanol at a weight ratio of 1 / 1.8 was supplied to the reaction tube at a supply rate of 28 g / hr to cause a reaction. Space velocity W at this time
The HSV was 10 hr ^-1 and the temperature (reaction temperature) of the catalyst layer was 350 ° C. The reaction product was collected every hour under water cooling and analyzed by gas chromatography. Table 11 shows the reaction results.

After the completion of the reaction, the supply of the methanol solution of cyclohexanone oxime was stopped, and nitrogen gas 2.5 l / hr,
2.5 l / hr of air was mixed and bubbled into methanol kept at 0 ° C., and methanol (3.8% by volume, 0 ° C. saturated concentration) was vaporized and entrained in a mixed gas of nitrogen and air to the reaction tube. Then, the temperature of the catalyst layer was increased to 430 ° C., and the catalyst layer was burned for 40 hours. By this operation, the carbonaceous substance deposited on the catalyst was removed.

Next, the temperature was lowered to 350 ° C. while supplying nitrogen gas (4.2 l / hr). Subsequently, the reaction was carried out in the same manner under the above reaction conditions.

After the completion of the reaction, the carbonaceous substance deposited on the catalyst was removed by the same operation as described above.

Further, the above-mentioned reaction and the operation of removing the carbonaceous substance were repeated 20 times in total. Table 11 shows the reaction results.

(Method for Producing ε-Caprolactam of the Present Invention) A stainless steel reaction tube was filled with 0.375 g of the catalyst after removing the carbonaceous material, and nitrogen gas (4.2 l / hr) was used.
A pre-heat treatment was performed at 350 ° C. for 1 hour at normal pressure in an air stream. Next, the temperature was lowered to 200 ° C. and maintained, and the nitrogen gas pressure was increased to 8 kg /
cm ² . The supply of nitrogen was stopped, and a 28% by weight aqueous ammonia solution was supplied from the upper portion of the reaction tube at 3.0 g / hr for 3 hours. During this time, the pressure of the catalyst packed bed was maintained at 8 kg / cm ² . Thereafter, the supply of the aqueous ammonia solution was stopped, and the temperature was lowered to room temperature (20 ° C.) at normal pressure under a stream of nitrogen gas (4.2 l / hr).

The catalyst 0.37 thus regenerated and treated
5 g was transferred to a quartz glass reaction tube, and nitrogen gas (4.
2 l / hr) preheat treatment at 350 ° C. for 1 hour under an air stream, then cyclohexanone oxime / methanol weight ratio = 1 /
The mixed liquid of 1.8 was supplied to the reaction tube at a supply rate of 10.5 g / hr to cause a reaction. The WHSV at this time was 10 hr ^-1 . Table 12 shows the reaction results.

[0077]

[Table 11]

[0078]

[Table 12]

Example 7 (Method for producing ε-caprolactam) 0.375 g (0.6 ml) of the catalyst A * prepared in Example 2 was charged into a reaction tube.
In the same manner as in Example 1, the Beckmann rearrangement reaction of cyclohexanone oxime and the operation of removing the carbonaceous substance were repeatedly performed. Table 13 shows the reaction results.

(Method for Producing ε-Caprolactam of the Present Invention) 0.375 g of the deteriorated catalyst after removing the carbonaceous material was put in an autoclave, 50 ml of a 28% by weight aqueous ammonia solution was added, and the mixture was kept at 90 ° C. for 3 hours. Thereafter, the solid was filtered, washed with water, and dried.

The catalyst thus regenerated was filled in the same reaction tube as above, and a Beckmann rearrangement reaction of cyclohexanone oxime was carried out in the same manner as above. Table 14 shows the reaction results.

[0082]

[Table 13]

[0083]

[Table 14]

Comparative Example 1 Using 0.375 g of the catalyst A, the reaction in Example 1 (the method for producing ε-caprolactam) and the operation of removing the carbonaceous substance were repeated 20 times in total in the same manner as in Example 1. . Table 15 shows the results of the twentieth reaction.

[0085]

[Table 15]

6. The autoclave was charged with 0.375 g of the deteriorated catalyst after removing the carbonaceous substance at the 20th time.
Add 50 ml of a 5% by weight aqueous solution of ammonium nitrate and add 90 ml.
C. for 1 hour. This solid was then filtered, washed with water,
Dried. A catalyst treated in this way was obtained.

0.375 g of this catalyst was charged into a quartz glass reaction tube as described above, and the reaction was carried out as described above. Table 16 shows the results of the first reaction.

[0088]

[Table 16]

Example 8 A Beckmann rearrangement reaction was carried out in the same manner as in Example 1, except that 0.375 g of the catalyst C prepared in Reference Example 3 was charged. Table 17 shows the reaction results.

[0090]

[Table 17]

(Forced Degradation and Reaction of Catalyst by High Temperature) 0.375 g (0.6 ml) of the catalyst C prepared in Reference Example 3 was charged into a quartz glass reaction tube having an inner diameter of 1 cm, and nitrogen gas (2.5 l) was added. / Hr) in distilled water maintained at 0 ° C, and water (0.6% by volume, 0 ° C saturated concentration) in nitrogen gas.
Was vaporized and held at 900 ° C. for 2 hours, and then cooled to room temperature (20 ° C.). Using 0.375 g of the catalyst thus treated at a high temperature, a Beckmann rearrangement reaction was performed in the same manner as in the reaction of Example 1. The reaction results are shown in Table 18.

[0092]

[Table 18]

Next, the carbonaceous substance deposited on the catalyst was removed by burning in the same manner as in Example 1.

(Method for producing ε-caprolactam of the present invention) 0.375 g of the deteriorated catalyst after removing the carbonaceous material was put in an autoclave, and 50 ml of a 28% by weight aqueous ammonia solution and 4 g of ammonium chloride were added thereto. 90
C. for 1 hour.

After holding, the filtered solid was transferred to a flask, and 50 ml of 5N hydrochloric acid was added thereto, followed by stirring at 90 ° C. for 1 hour. Then the solid was filtered, washed with water and dried.

Using the regenerated catalyst, a Beckmann rearrangement reaction was performed in the same manner as described above. Table 19 shows the reaction results.

[0097]

[Table 19]

──────────────────────────────────────────────────続 き Continuation of the front page (56) References JP-A-62-123167 (JP, A) JP-A-57-139062 (JP, A) JP-A-64-80443 (JP, A) JP-A-1- 99649 (JP, A) JP-A-61-38630 (JP, A) JP-A-64-42227 (JP, A) (58) Fields investigated (Int. Cl. ⁷ , DB name) C07D 223/10 B01J 21 / 08 B01J 29/04 C07B 61/00 300

Claims (3)

(57) [Claims] 1. A method for producing ε-caprolactam from cyclohexanone oxime using a zeolite catalyst under gas phase reaction conditions, wherein the reduced activity zeolite catalyst is regenerated by contacting it with ammonia, and then the catalyst is recovered. A method for producing ε-caprolactam, which is used in a reaction. 2. The method for producing ε-caprolactam according to claim 1, wherein the zeolite catalyst having reduced activity is crystalline silica or crystalline metallosilicate. 3. The method for producing ε-caprolactam according to claim 1, wherein the temperature at which the reduced activity zeolite catalyst is brought into contact with ammonia is 50 to 250 ° C.