JP2018076235A - Method for producing ε-caprolactam - Google Patents

Abstract

The present invention provides a method for producing ε-caprolactam with a high reaction rate and a high selectivity by a rearrangement reaction even when cyclohexanone oxime produced using cyclohexylamine as a raw material is used. Let it be an issue. A method for producing ε-caprolactam comprising the step (A) of producing cyclohexanone oxime by oxidizing cyclohexylamine, and a gas phase using a solid catalyst in the presence of a lower alcohol. Including the step (B) of producing ε-caprolactam from the cyclohexanone oxime by Beckmann rearrangement reaction, and the amount of cyclohexylamine contained in the cyclohexanone oxime in the step (B) is represented by the following formulas (1): (1) 0 ≦ {[cyclohexylamine (mass) / cyclohexanone oxime (mass)] × 100} ≦ 5.0. [Selection figure] None

Description

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

  ε-Caprolactam is an important basic chemical raw material used as a raw material for nylon and the like. As a method for producing this ε-caprolactam, a method having a step of performing a rearrangement reaction (Beckmann rearrangement) of cyclohexanone oxime in a gas phase reaction using a solid catalyst is known. In addition, a method in which a lower alcohol is allowed to coexist in this rearrangement reaction is also disclosed (Patent Document 1). According to this method, a very high selectivity is obtained even under conditions where the reaction rate of cyclohexanone oxime is substantially around 100%. Can yield ε-caprolactam and can significantly improve the life of the catalyst.

  And cyclohexanone oxime used in the production method of ε-caprolactam is often produced industrially using cyclohexanone as a raw material, but cyclohexanone oxime can be produced by other methods, for example, using cyclohexylamine as a raw material. Can be manufactured. As a method for producing cyclohexanone oxime using cyclohexylamine as a raw material, methods using hydrogen peroxide or molecular oxygen as an oxidizing agent are disclosed (Patent Documents 2 to 4). According to these methods, since cyclohexanone oxime can be produced at a lower cost compared to a method using cyclohexanone as a raw material, it is expected that ε-caprolactam can also be produced at a lower cost.

Japanese Patent No. 2616088 JP-A-4-354539 Japanese Patent No. 4895610 International Publication No. 2014/103850

  However, as a result of investigation by the present inventors, when ε-caprolactam is produced by subjecting cyclohexanone oxime produced using cyclohexylamine as a raw material to Beckmann rearrangement by a gas phase reaction, high reaction rate and selectivity are obtained. As a result, it has been found that it is difficult to produce ε-caprolactam at low cost.

  Accordingly, an object of the present invention is to provide a method for producing ε-caprolactam with a high reaction rate and high selectivity even when cyclohexanone oxime produced using cyclohexylamine as a raw material is used.

  As a result of diligent studies to solve the above problems, the inventors of the present invention, in the rearrangement reaction of cyclohexanone oxime, when cyclohexanone oxime contains a specific impurity in a specific amount range, that is, cyclohexanone oxime has cyclohexylamine, It was found that when cyclohexanone and nitrocyclohexane are contained in a specific amount range, the rearrangement reaction of cyclohexanone oxime is inhibited, and the present invention has been completed.

That is, the present invention includes the following preferred embodiments.
[1] A method for producing ε-caprolactam, the method comprising:
Step (A) for producing cyclohexanone oxime by oxidizing cyclohexylamine, and Step (B) for producing ε-caprolactam from cyclohexanone oxime by gas phase Beckmann rearrangement reaction using a solid catalyst in the presence of a lower alcohol.
Including
The amount of cyclohexylamine contained in the cyclohexanone oxime in the step (B) is represented by the following formula (1):
(1) 0 ≦ {[cyclohexylamine (mass) / cyclohexanone oxime (mass)] × 100} ≦ 5.0
Meet the way.
[2] The amount of cyclohexanone contained in the cyclohexanone oxime in the step (B) is represented by the following formula (2):
(2) 0 ≦ {[cyclohexanone (mass) / cyclohexanone oxime (mass)] × 100} ≦ 5.0
The method according to [1], wherein
[3] The amount of nitrocyclohexane contained in the cyclohexanone oxime in the step (B) is represented by the following formula (3):
(3) 0 ≦ {[Nitrocyclohexane (mass) / cyclohexanone oxime (mass)] × 100} ≦ 15
The method according to [1] or [2], wherein
[4] The method according to any one of [1] to [3], further including a step (C) of hydrolyzing cyclohexylidenecyclohexylamine contained in the reaction solution obtained by the gas phase reaction to recover cyclohexylamine. the method of.
[5] The method according to any one of [1] to [4], wherein the solid catalyst is zeolite.

  According to the present invention, even when cyclohexanone oxime produced using cyclohexylamine as a raw material is used, a method for producing ε-caprolactam with high reaction rate and high selectivity can be provided by the rearrangement reaction. .

The present invention is a method for producing ε-caprolactam,
Step (A) for producing cyclohexanone oxime by oxidizing cyclohexylamine, and Step (B) for producing ε-caprolactam from cyclohexanone oxime by gas phase Beckmann rearrangement reaction using a solid catalyst in the presence of a lower alcohol.
including.

The amount of cyclohexylamine contained in the cyclohexanone oxime in the step (B) is represented by the following formula (1):
(1) 0 ≦ {[cyclohexylamine (mass) / cyclohexanone oxime (mass)] × 100} ≦ 5.0
Meet.

  The value of the above formula {[cyclohexylamine (mass) / cyclohexanone oxime (mass)] × 100} is preferably 5.0 or less, more preferably 3.0 or less, further preferably 2.0 or less, and 1.0 or less. Is particularly preferable, and 0.5 or less is very preferable. In the manufacturing method of this invention as it is below the said upper limit, a high reaction rate and selectivity can be obtained. In addition, the value of the above formula {[cyclohexylamine (mass) / cyclohexanone oxime (mass)] × 100} is usually 0 or more, for example, 0.01 or more. In the present invention, the reaction rate means the ratio of reacted cyclohexanone oxime to cyclohexanone oxime based on the amount of substance, and the selectivity means the ratio of ε-caprolactam to reacted cyclohexanone oxime based on the amount of substance. .

  In the present invention, since cyclohexanone oxime is obtained by oxidizing cyclohexylamine using molecular oxygen or the like, cyclohexanone oxime may contain cyclohexylamine as a raw material.

In the step (B), the amount of cyclohexanone contained in the cyclohexanone oxime is represented by the following formula (2):
(2) 0 ≦ {[cyclohexanone (mass) / cyclohexanone oxime (mass)] × 100} ≦ 5.0
It is preferable to satisfy.

  The value of the above formula {[cyclohexanone (mass) / cyclohexanone oxime (mass)] × 100} is preferably 5.0 or less, more preferably 3.0 or less, further preferably 1.0 or less, and 0.5 or less. Highly preferred. In the manufacturing method of this invention as it is below the said upper limit, a higher reaction rate and selectivity can be obtained. The value of the above formula {[cyclohexanone (mass) / cyclohexanone oxime (mass)] × 100} is usually 0 or more, for example, 0.01 or more.

  The cyclohexanone can be produced as a by-product by reacting water with cyclohexanone oxime because water is generated as a by-product when cyclohexylamine as a raw material is oxidized to synthesize cyclohexanone oxime.

In the step (B), the amount of nitrocyclohexane contained in the cyclohexanone oxime is represented by the following formula (3):
(3) 0 ≦ {[Nitrocyclohexane (mass) / cyclohexanone oxime (mass)] × 100} ≦ 15
It is more preferable to satisfy.

  The value of the above formula {[nitrocyclohexane (mass) / cyclohexanone oxime (mass)] × 100} is preferably 15 or less, more preferably 10 or less, further preferably 5 or less, and very preferably 2.5 or less. In the manufacturing method of this invention as it is below the said upper limit, a higher reaction rate and selectivity can be obtained. The value of the above formula {[nitrocyclohexane (mass) / cyclohexanone oxime (mass)] × 100} is usually 0 or more, for example, 0.1 or more.

  The nitrocyclohexane can be produced as a by-product when the amine moiety of cyclohexylamine as a raw material is oxidized.

  In the present invention, the cyclohexanone oxime is obtained by oxidizing cyclohexylamine. The oxidizing agent used when oxidizing cyclohexylamine is not particularly limited, and examples thereof include organic peroxides, hydrogen peroxide, and molecular oxygen.

  One embodiment of the present invention further includes a step (C) of hydrolyzing cyclohexylidenecyclohexylamine contained in the reaction solution obtained by the gas phase reaction to recover cyclohexylamine. The cyclohexylamine recovered in this step can be recycled and used again as a raw material in the production of cyclohexanone oxime. Note that cyclohexylidenecyclohexylamine can be produced by a reaction between cyclohexanone that can be by-produced when synthesizing cyclohexanone oxime by oxidation of cyclohexylamine as a raw material and cyclohexylamine as a raw material.

  Cyclohexylamine, cyclohexanone and nitrocyclohexane contained in cyclohexanone oxime can be separated by a usual method. For example, cyclohexanone oxime in which the amounts of impurities cyclohexylamine, cyclohexanone, and nitrocyclohexane are controlled so as to satisfy the above formulas (1) to (3) can be obtained by extraction, distillation, crystallization, or the like.

  Cyclohexylamine, cyclohexanone, and nitrocyclohexane can suppress the mixing amount in cyclohexanone oxime to 5 mass% or less, 2 mass% or less, and 1 mass% or less, respectively, by distillation. Furthermore, by performing crystallization after the distillation, cyclohexylamine, cyclohexanone, and nitrocyclohexane can be suppressed to below the lower limit of detection in gas chromatography analysis. Examples of the solvent used in the crystallization include aliphatic straight chain hydrocarbons having 6 to 12 carbon atoms, aliphatic side chain hydrocarbons, alicyclic hydrocarbons, alcohols, and water. More specifically, aliphatic linear hydrocarbons such as hexane, heptane, octane, nonane and decane, aliphatic side chain hydrocarbons such as methylhexane, isooctane and neohexane, methylcyclopentane, cyclohexane and methylcyclohexane. Examples thereof include alicyclic hydrocarbons, alcohols such as methanol, ethanol, n-propanol, and n-butanol, and water. These may be used alone or in admixture of two or more.

  The amount of the solvent used for crystallization can be about 0.1 to about 5 times by mass, preferably about 0.3 to about 4 times by mass, per cyclohexanone oxime.

  Specific methods for crystallization include, for example, a method in which crude cyclohexanone oxime is dissolved in the above solvent and cooled to precipitate crystals of cyclohexanone oxime, and the solvent is evaporated under reduced pressure and cooled with the latent heat of vaporization to produce crystals. And a method of precipitating cyclohexanone oxime crystals by mixing a crude cyclohexanone oxime in a molten state or a mixture of the above solvent and crude cyclohexanone oxime and a cooled solvent. By this crystallization operation, most of the impurities contained in the crude cyclohexanone oxime are discharged into the solvent. Next, the crystal is separated from the solvent by means such as filtration or sedimentation, and the obtained crystal is washed with the above-described solvent or the like as necessary. The washing may be a method of suspending in the above-mentioned solvent, stirring, then separating the solvent from the crystal by means of filtration, sedimentation, or the like, or a method of filtering while directly spraying the solvent on the crystal.

  The crystallization temperature may be about 0 ° C. or higher and less than the melting point of cyclohexanone oxime.

  In the present invention, the solid catalyst is not particularly limited as long as it is a solid catalyst for producing ε-caprolactam used when a cyclohexanone oxime is rearranged in the gas phase to convert to ε-caprolactam. Examples of the solid catalyst include zeolite, boric acid catalyst, silica / alumina catalyst, solid phosphoric acid catalyst, and composite metal oxide. Among them, zeolite is preferable, pentasil-type zeolite is more preferable, and MFI zeolite is more preferable for producing ε-caprolactam with high yield over a long period of time.

  The zeolite may be crystalline silica whose skeleton is substantially composed of silicon and oxygen, or a crystalline metallo that further contains elements other than silicon and oxygen, such as metal elements, as elements constituting the skeleton. It may be a silicate or the like. Examples of elements other than silicon and oxygen in the crystalline metallosilicate include Be, B, Al, Ti, V, Cr, Fe, Co, Ni, Cu, Zn, Ga, Ge, Zr, Nb, Sb, La, Hf, Bi, etc. are mentioned, These 2 or more types may be contained as needed. Further, the atomic ratio of silicon to these elements is preferably 50 or more, more preferably 500 or more.

  For example, the zeolite is hydrothermally synthesized using, for example, a silicon compound, a quaternary ammonium compound, water and, if necessary, a metal compound, and the obtained crystal is dried and calcined, and then contacted with ammonia or an ammonium salt. Then, it can be suitably prepared by drying.

  The particle size of the solid catalyst is preferably 0.0001 to 5 mm, more preferably 0.001 to 3 mm, from the viewpoint of catalytic activity. In addition, the solid catalyst may be, for example, a molded body substantially consisting of only the catalyst component, or may be one in which the catalyst component is supported on a carrier.

  In the present invention, the lower alcohol is usually an alcohol having 6 or less carbon atoms, preferably an alcohol having 5 or less carbon atoms. The alcohol may be linear or branched, and may have a halogen group such as fluorine, chlorine, or bromine as a substituent. Examples of the lower alcohol include methanol, ethanol, 1-propanol (n-propyl alcohol), 2-propanol (isopropyl alcohol), 1-butanol (n-butyl alcohol), 2-butanol (sec-butyl alcohol), 2 -Methyl-1-propanol (isobutyl alcohol), 1-pentanol (n-pentyl alcohol), 1-hexanol (n-hexyl alcohol) and 2,2,2-trifluoroethanol. Of these, methanol, ethanol, 1-propanol, 2-propanol and 1-butanol are preferred from the viewpoint of being particularly excellent in improving selectivity of ε-caprolactam and catalyst life, and methanol and ethanol are more preferred from an industrial viewpoint.

  The said lower alcohol may be used independently and may be used in combination of 2 or more type. When two or more types are used in combination, the combination and ratio can be arbitrarily selected. However, considering the handleability and the like, it is preferable to use the lower alcohol alone.

  In the present invention, a molecular oxygen-containing gas may coexist in the reaction system. It is economical and preferable to use air as the molecular oxygen-containing gas. The molecular oxygen concentration in the molecular oxygen-containing gas is preferably outside the explosion composition range.

  The amount of molecular oxygen in the reaction system during the gas phase reaction is preferably from 0.1 to 10 mol, and preferably from 0.3 to 5 mol, per 1 mol of cyclohexanone oxime as a raw material. More preferred.

  The gas phase reaction can be carried out by a gas phase contact reaction of a normal fixed bed method, fluidized bed method, or moving bed method. The raw material cyclohexanone oxime reacts in contact with the solid catalyst layer in the gaseous state, but the lower alcohol may be premixed with cyclohexanone oxime in the gaseous state, or separately from the cyclohexanone oxime in the reactor. You may supply. When performing a fixed bed type gas phase catalytic reaction, it is preferable to pass through a layer of a solid catalyst in a state where cyclohexanone oxime and a lower alcohol are sufficiently mixed. On the other hand, when conducting a fluidized bed type gas phase catalytic reaction, cyclohexanone oxime and lower alcohol do not necessarily have to be mixed in advance, and these may be separately supplied to the reactor. Alcohol may be divided and supplied. In addition, when performing a fluidized bed type gas phase catalytic reaction, lower alcohol may be supplied upstream of cyclohexanone oxime.

  In the case of using a molecular oxygen-containing gas, the molecular oxygen-containing gas can be supplied by mixing with a lower alcohol and cyclohexanone oxime, or mixed with a lower alcohol, and more reactive than cyclohexanone oxime. It may be supplied upstream.

  The lower alcohol added to the gas phase reaction system can be separated and recovered from the reaction product and reused.

  The gas phase reaction may be performed in the presence of a vapor of a compound inert to the reaction, such as benzene, cyclohexane, or toluene, as a diluent gas, or an inert gas such as nitrogen or carbon dioxide. You may go.

  The gas phase reaction is preferably performed under atmospheric pressure or under reduced pressure below atmospheric pressure.

  The reaction temperature during the gas phase reaction is preferably 250 to 500 ° C, more preferably 300 to 450 ° C, and even more preferably 300 to 400 ° C. When the reaction temperature is at least the above lower limit, the reaction rate is improved, and the selectivity for ε-caprolactam is further improved. Moreover, thermal decomposition of cyclohexanone oxime is suppressed as reaction temperature is below the said upper limit, and the selectivity of (epsilon) -caprolactam improves more.

The space velocity (WHSV) of cyclohexanone oxime during the gas phase reaction is preferably 0.1 to 40 h ⁻¹ (that is, the supply rate of cyclohexanone oxime per kg of the solid catalyst is 0.1 to 40 kg / h), more preferably 0.2~20h ^-1, further preferably 0.5~10h ^-1.

  Ε-Caprolactam produced by the gas phase reaction can be separated from the reaction mixture by a known method. For example, the reaction product gas is cooled and condensed, and then separated by extraction, distillation, crystallization, or the like to obtain purified ε-caprolactam.

  The solid catalyst can be removed by burning (calcining) the carbonaceous material adhering in the gas phase reaction at a temperature of 200 to 600 ° C. with a molecular oxygen-containing gas, and is easily activated to the original performance. Can be reused repeatedly. The carbonaceous material may be removed in the presence of alcohol in the molecular oxygen-containing gas.

  The combustion treatment with the molecular oxygen-containing gas may be performed at 200 to 600 ° C. under a constant temperature condition or under a condition where the temperature is raised in multiple stages.

  As the molecular oxygen-containing gas, air is usually suitable, but air or oxygen may be diluted with an inert gas such as nitrogen, argon or carbon dioxide. The oxygen concentration in the molecular oxygen-containing gas is preferably 1 to 30% by volume, more preferably 5 to 25% by volume.

  Hereinafter, the present invention will be described in more detail with reference to examples. However, the present invention is not limited to the following examples.

In the following examples, the space velocity WHSV (h ⁻¹ ) was calculated by dividing the supply rate (g / h) of cyclohexanone oxime by the mass (g) of the solid catalyst.

Moreover, the analysis of cyclohexanone oxime and ε-caprolactam was performed by gas chromatography, and the reaction rate, selectivity and yield of cyclohexanone oxime were calculated by the following formulas, respectively. In the formula, the amount of cyclohexanone oxime supplied was X (mol), the amount of unreacted cyclohexanone oxime was Y (mol), and the amount of ε-caprolactam produced was Z mol.
Reaction rate of cyclohexanone oxime (%) = [(XY) / X] × 100
Selectivity of ε-caprolactam (%) = [Z / (XY)] × 100
Yield (%) = [(reaction rate of cyclohexanone oxime) × (selectivity of ε-caprolactam)] / 100

[Reference Example 1]
[Preparation of catalyst A]
In a 24 L autoclave, 5300 g of pure water, 8930 g of 10% nitric acid water, and 800 g of montmorillonite (Kunimine F manufactured by Kunimine Kogyo Co., Ltd.) 800 g were added, and the resulting mixture was heated to 90 ° C. with stirring. 995 g of a mass% titanium sulfate (IV) solution (Ti (SO ₄ ) ₂ , manufactured by Wako Pure Chemical Industries, Ltd.) was added dropwise over 0.5 hours. After completion of the dropping, stirring was continued at 90 ° C. for 4 hours, and after 4 hours, the mixture was cooled to room temperature and stirring was stopped. The obtained mixture was subjected to pressure filtration to separate a solid, and 17 kg of pure water was added to the solid, followed by washing and filtration by pressure filtration. After washing filtration, 14 kg of pure water was further added, and washing filtration was performed by pressure filtration. The obtained solid was dried at 110 ° C. overnight to prepare catalyst A (montmorillonite containing titanium ions between layers).

[Reference Example 2]
[Preparation of cyclohexylamine oxidation reaction solution]
In a reactor made of SUS316 (capacity: 24 L) equipped with a thermocouple, stirring blade, gas supply line and gas discharge line, 15.7 g of catalyst A obtained in Reference Example 1 and cyclohexylamine (Wako Pure Chemical Industries, Ltd.) )), 8 kg of toluene (manufactured by Wako Pure Chemical Industries, Ltd.), and 160 g of cyclohexanone, and after replacing the gas phase part in the reactor with nitrogen, sealing the gas phase part in the reactor Nitrogen gas was introduced into the reactor to adjust the pressure in the reactor to 0.65 MPa (gauge pressure). Next, while stirring, nitrogen gas is blown into the liquid phase of the mixture in the reactor at a flow rate of 6 L / h, and the gas is passed through the reactor through the gas discharge line through the reactor. While discharging, the temperature was raised to 100 ° C. After raising the temperature to 100 ° C., instead of nitrogen gas, a mixed gas of oxygen and nitrogen (oxygen concentration: 6.93 vol%) was blown at a flow rate of 6 L / h, and gas was discharged from the gas phase part in the reactor. While discharging the gas through the line, the reactor was stirred at 100 ° C. for 38 hours while maintaining the pressure in the reactor at 0.65 MPa (gauge pressure). After 38 hours, the mixture was cooled, stirring was stopped, and the catalyst was allowed to settle naturally. Subsequently, after allowing the catalyst to settle naturally, the supernatant liquid was extracted to obtain 6690 g of a reaction liquid A. The reaction solution A was analyzed by gas chromatography, and the contents of cyclohexylamine, cyclohexanone, cyclohexanone oxime, and nitrocyclohexane contained in the reaction solution A were determined from the obtained analysis values. The content of cyclohexylamine was 18. The content of 2% by mass, the content of cyclohexanone was 1.29% by mass, the content of cyclohexanone oxime was 16.1% by mass, and the content of nitrocyclohexane was 0.28% by mass. The conversion of cyclohexylamine was 31.3%, and the selectivity for cyclohexanone oxime was 77.1%.

[Reference Example 3]
[Purification of Reaction Solution A]
5 kg of the reaction liquid A is put in a 10-liter SUS tank equipped with a jacket and a stirring blade, and distilled under reduced pressure at 40 Torr and 90 ° C. to distill 2710 g, and the remaining in the SUS tank. As a fraction A, 2280 g was obtained. When the contents of cyclohexylamine, cyclohexanone, cyclohexanone oxime and nitrocyclohexane contained in fraction A were determined, the content of cyclohexylamine was 21.9% by mass, the content of cyclohexanone was 2.14% by mass, and cyclohexanone oxime. The content of was 36.8% by mass, and the content of nitrocyclohexane was 0.45% by mass.
2 kg of fraction A was placed in a 5 liter SUS tank equipped with a jacket and a stirring blade, and distilled under reduced pressure at 10 Torr and 130 ° C. to obtain 949 g as fraction B. When the contents of cyclohexylamine, cyclohexanone, cyclohexanone oxime and nitrocyclohexane contained in fraction B were determined, the content of cyclohexylamine was 22.4% by mass, the content of cyclohexanone was 0.30% by mass, and cyclohexanone oxime. The content of was 56.7% by mass, and the content of nitrocyclohexane was 0.55% by mass.
900 g of fraction B was placed in a 2 L separable flask equipped with a jacket, a stirring blade, a packed tower with an inner diameter of 30 mm and a height of 500 mm packed with Dixon packing 6 mmφ, a reflux timer, 50 Torr, 145 ° C., reflux ratio 5 ( The mixture was distilled under reduced pressure under the conditions of reflux timer open / closed = 3 seconds / 15 seconds, and 250 g was distilled to obtain 627 g as fraction C remaining in the separable flask. The contents of cyclohexylamine, cyclohexanone, cyclohexanone oxime, and nitrocyclohexane contained in fraction C were determined. The content of cyclohexylamine was 4.16% by mass, the content of cyclohexanone was 0.94% by mass, and cyclohexanone oxime. The content of was 84.6% by mass, and the content of nitrocyclohexane was 0.26% by mass.
To a 2 liter reactor, 600 g of fraction C and 290 g of n-heptane solvent were added. After heating up to 70 degreeC and dissolving cyclohexanone oxime, it cooled to 4 degreeC, stirring. The precipitated cyclohexanone oxime crystals were collected by filtration. To the cyclohexanone oxime crystals thus obtained, 290 g of an n-heptane solvent was added, stirred until the temperature was maintained at 0.1 ° C., and filtered. Further, 290 g of an n-heptane solvent was added to the crystals, and the mixture was stirred and then filtered until the temperature was maintained at 0.6 ° C. Next, 370 g of a methanol / water mixed solvent having a mass ratio of 1 / 1.44 was added, and the mixture was stirred and then filtered until the temperature was maintained at 0.1 ° C. 190 g of a methanol / water mixed solvent having a mass ratio of 1 / 1.44 was added to the obtained crystals, and the mixture was stirred until it was maintained at 2.6 ° C. and filtered. Further, 190 g of a methanol / water mixed solvent having a mass ratio of 1 / 1.44 was added and stirred until the temperature was maintained at 3.7 ° C. After filtration, 490 g of water was added and the temperature was maintained at 3.5 ° C. And filtered to obtain 376 g (yield 74.1%) of cyclohexanone oxime crystals. When the cyclohexanone oxime crystal thus obtained was analyzed, the purity of cyclohexanone oxime was 99.9%, the impurity content was less than the detection limit for cyclohexylamine, cyclohexanone and nitrocyclohexane, and the water content was 0.39%. there were.

[Example 1]
Using the cyclohexanone oxime crystal obtained in Reference Example 3, a mixture A of methanol / cyclohexanone oxime (water content in cyclohexanone oxime = 4.5 wt%) = 1.8 / 1 (mass ratio) was prepared. As a solid catalyst, 0.375 g of a particle having a particle size of 0.3 mm or less mainly composed of MFI zeolite made of crystalline silica (Si / Al atomic ratio = 147000) is packed in a quartz glass reaction tube having an inner diameter of 1 cm. A solid catalyst layer was formed and preheated at 340 ° C. for 1 hour under a nitrogen gas flow of 4.2 L / h. Next, 8.4 g of a mixture of methanol / cyclohexanone oxime (water content in cyclohexanone oxime: 4.5 mass%) = 1.8 / 1 (mass ratio) under a nitrogen gas flow at 4.2 L / h. / H (cyclohexanone oxime WHSV: 8 h ⁻¹ ) was supplied to the reaction tube, and the reaction was carried out for 20 hours while maintaining the temperature of the solid catalyst layer at 380 ° C. At this time, the masses of cyclohexylamine, cyclohexanone and nitrocyclohexane in the reaction system satisfied the following relationship with respect to formulas (a) to (c).
(A) {[cyclohexylamine (mass) / cyclohexanone oxime (mass)] × 100} = 0
(B) {[cyclohexanone (mass) / cyclohexanone oxime (mass)] × 100} = 0
(C) {[Nitrocyclohexane (mass) / cyclohexanone oxime (mass)] × 100} = 0

  After 20 hours from the start of the reaction, the reaction was terminated, and the reaction rate of cyclohexanone oxime and the selectivity of ε-caprolactam were calculated. The results are shown in Table 1.

[Example 2]
As shown in Table 1, ε-caprolactam was produced in the same manner as in Example 1 except that the value of formula (a) was changed to 0.1 instead of 0.

[Example 3]
As shown in Table 1, ε-caprolactam was produced in the same manner as in Example 1 except that the value of formula (a) was changed to 0.5 instead of 0.

[Example 4]
As shown in Table 1, ε-caprolactam was produced in the same manner as in Example 1 except that the value of the formula (a) was changed to 1.0 instead of 0.

[Example 5]
As shown in Table 1, ε-caprolactam was produced in the same manner as in Example 1 except that the value of the formula (a) was changed to 2.0 instead of 0.

[Example 6]
As shown in Table 1, ε-caprolactam was produced in the same manner as in Example 1 except that the value of the formula (a) was changed to 5.0 instead of 0.

[Example 7]
As shown in Table 1, ε-caprolactam was produced in the same manner as in Example 1 except that the value of formula (b) was changed to 1.0 instead of 0.

[Example 8]
As shown in Table 1, ε-caprolactam was produced in the same manner as in Example 1 except that the value of formula (b) was changed to 5.0 instead of 0.

[Example 9]
As shown in Table 1, ε-caprolactam was produced in the same manner as in Example 1 except that the value of formula (b) was changed to 10.0 instead of 0.

[Example 10]
As shown in Table 1, ε-caprolactam was produced in the same manner as in Example 1 except that the value of formula (c) was changed to 2.0 instead of 0.

[Example 11]
As shown in Table 1, ε-caprolactam was produced in the same manner as in Example 1 except that the value of formula (c) was changed to 10.0 instead of 0.

[Example 12]
As shown in Table 1, ε-caprolactam was produced in the same manner as in Example 1 except that the value of the formula (c) was changed to 20.0 instead of 0.

[Example 13]
As shown in Table 1, the value of formula (a) is changed to 5.0 instead of 0, the value of formula (b) is changed to 5.0 instead of 0, and the value of formula (c) is changed to 0. Except for 15.0, ε-caprolactam was produced in the same manner as in Example 1.

[Comparative Example 1]
As shown in Table 1, ε-caprolactam was produced in the same manner as in Example 1 except that the value of formula (a) was changed to 10.0 instead of 0.

[Comparative Example 2]
As shown in Table 1, the value of the expression (a) is changed to 10.0, the value of the expression (b) is changed to 10.0, and the value of the expression (c) is changed to 0. Except for 20.0, ε-caprolactam was produced in the same manner as in Example 1.

In each of Examples 1 to 13, ε-caprolactam could be produced with excellent selectivity and reaction rate.
On the other hand, in Comparative Example 1 in which the value of the formula (a) was high, the reaction rate was good, but the selectivity was low and the yield was lowered. In addition, as the value of the mass percentage (b) of cyclohexanone is increased, and in Comparative Example 2 where all the values of the formulas (a) to (c) are high, both the reaction rate and the selectivity are decreased, and the yield The result was also low.

  According to the present invention, even when cyclohexanone oxime that can be synthesized at low cost by oxidizing cyclohexylamine with molecular oxygen or the like can be used, the reaction rate and selectivity in the rearrangement reaction can be maintained at a very high level. The cost can be reduced.

Claims (5)

A method for producing ε-caprolactam, the method comprising:
Step (A) for producing cyclohexanone oxime by oxidizing cyclohexylamine, and Step (B) for producing ε-caprolactam from cyclohexanone oxime by gas phase Beckmann rearrangement reaction using a solid catalyst in the presence of a lower alcohol.
Including
The amount of cyclohexylamine contained in the cyclohexanone oxime in the step (B) is represented by the following formula (1):
(1) 0 ≦ {[cyclohexylamine (mass) / cyclohexanone oxime (mass)] × 100} ≦ 5.0
Meet the way. The amount of cyclohexanone contained in the cyclohexanone oxime in the step (B) is represented by the following formula (2):
(2) 0 ≦ {[cyclohexanone (mass) / cyclohexanone oxime (mass)] × 100} ≦ 5.0
The method of claim 1, wherein: The amount of nitrocyclohexane contained in the cyclohexanone oxime in the step (B) is represented by the following formula (3):
(3) 0 ≦ {[Nitrocyclohexane (mass) / cyclohexanone oxime (mass)] × 100} ≦ 15
The method according to claim 1 or 2, wherein:   The method according to any one of claims 1 to 3, further comprising a step (C) of hydrolyzing cyclohexylidenecyclohexylamine contained in the reaction solution obtained by the gas phase reaction to recover cyclohexylamine.   The method according to claim 1, wherein the solid catalyst is zeolite.