WO2013058121A1

WO2013058121A1 - PRODUCTION METHOD FOR ε-CAPROLACTAM

Info

Publication number: WO2013058121A1
Application number: PCT/JP2012/075812
Authority: WO
Inventors: 杉田　啓介; 哲也横田; 尚己武田
Original assignee: 住友化学株式会社
Priority date: 2011-10-17
Filing date: 2012-10-04
Publication date: 2013-04-25
Also published as: IN2014CN02909A; JP6004884B2; KR20140090605A; CN103889950A; SG11201401106PA; JP2013100274A; KR101925168B1

Abstract

A production method for ε-caprolactam, including: a step in which a gas-phase reaction is performed whereby a cyclohexanone oxime is caused to come in contact with a solid catalyst, and the cyclohexanone oxime is converted to ε-caprolactam, in the coexistence of a lower alcohol; and a step in which the volumes of water, ammonia, and amine coexisting in the gas-phase reaction system are adjusted to the values in formulas (1-3). The lower alcohol in the ε-caprolactam production method includes a recovered lower alcohol that is recovered from a reaction mixture obtained by the gas-phase reaction. (1) 0≦{[ammonia (number of moles)/lower alcohol (number of moles)]×100}<14; (2) 0<{[water (number of moles)/lower alcohol (number of moles)]×100}<11; (3) 0≦{[amine (number of moles)/lower alcohol (number of moles)]×100}<7.5

Description

Method for producing ε-caprolactam

The present invention relates to a process for producing ε-caprolactam in which ε-caprolactam is produced from cyclohexanone oxime by a gas phase reaction using a solid catalyst.
This application claims priority based on Japanese Patent Application No. 2011-228142 filed in Japan on October 17, 2011, the contents of which are incorporated herein by reference.

ε-Caprolactam is an important basic chemical raw material used as a raw material for nylon and the like, and a method for producing ε-caprolactam includes a step of rearranging cyclohexanone oxime (Beckmann rearrangement) by a gas phase reaction using a solid catalyst. Are known. A method for improving the reaction rate of cyclohexanone oxime, the selectivity of ε-caprolactam and the catalyst life by carrying out the rearrangement reaction in the presence of a lower alcohol is disclosed (see Patent Document 1). According to this method, even when the reaction rate of cyclohexanone oxime is substantially near 100%, ε-caprolactam can be obtained with extremely high selectivity, and the life of the catalyst is remarkably improved.

Japanese Patent No. 2616088

In the production method described in Patent Document 1, the lower alcohol used in the rearrangement reaction can be recovered after the reaction and reused, which is an important process for producing ε-caprolactam at low cost. Become.
On the other hand, in order to improve the yield of ε-caprolactam, it is important to improve the reaction rate and selectivity by reducing the amount of impurities mixed in the rearrangement reaction. For example, the lower alcohol that is recovered and reused can be a major cause of contamination of the reaction system. Therefore, it is necessary to reduce such impurities. Thus, ε-caprolactam can be further improved in yield by reducing the amount of impurities.

The present invention has been made in view of the above circumstances, and an object of the present invention is to provide a method for producing ε-caprolactam having excellent reaction rate and selectivity in the rearrangement reaction of cyclohexanone oxime.

In order to solve the above-mentioned problems, the present invention provides a method for producing ε-caprolactam, which produces ε-caprolactam from cyclohexanone oxime by a gas phase reaction using a solid catalyst in the presence of a lower alcohol. A method for producing ε-caprolactam, comprising, as alcohol, lower alcohol recovered from the reaction mixture of the gas phase reaction, and adjusting the amounts of water, ammonia and amines to the following values during the gas phase reaction: I will provide a.
(1) 0 ≦ {[ammonia (number of moles) / lower alcohol (number of moles)] × 100} <14
(2) 0 <{[water (number of moles) / lower alcohol (number of moles)] × 100} <11
(3) 0 ≦ {[amines (number of moles) / lower alcohol (number of moles)] × 100} <7.5
In the method for producing ε-caprolactam according to the present invention, a gas mainly composed of a lower alcohol is distilled and separated from the reaction mixture, and a part thereof is cooled and condensed, and then further distilled. Is preferably at least part of the recovered lower alcohol.
In the method for producing ε-caprolactam of the present invention, the solid catalyst is preferably a zeolite.

ADVANTAGE OF THE INVENTION According to this invention, the manufacturing method of the epsilon caprolactam excellent in the reaction rate and selectivity in the rearrangement reaction of cyclohexanone oxime can be provided.
Further, by reusing the recovered lower alcohol, the amount of industrial waste can be reduced, and the burden on the environment can be reduced.

FIG. 3 is a flowchart showing manufacturing steps in a method for manufacturing ε-caprolactam according to an embodiment of the present invention.

The method for producing ε-caprolactam according to the present invention is a method for producing ε-caprolactam in which ε-caprolactam is produced from cyclohexanone oxime by a gas phase reaction using a solid catalyst in the presence of a lower alcohol. The lower alcohol to be coexisted includes a lower alcohol recovered from the reaction mixture of the gas phase reaction (hereinafter sometimes referred to as “recovered lower alcohol”), and the amount of water, ammonia and amines during the gas phase reaction. Is adjusted to the following value.
(1) 0 ≦ {[ammonia (number of moles) / lower alcohol (number of moles)] × 100} (hereinafter sometimes referred to as “mol percentage (a)”) <14
(2) 0 <{[water (number of moles) / lower alcohol (number of moles)] × 100} (hereinafter sometimes referred to as “mol percentage (b)”) <11
(3) 0 ≦ {[amines (number of moles) / lower alcohol (number of moles)] × 100} or less, sometimes referred to as “mole percentage (c)”. <7.5
In the gas phase reaction, a cyclohexanone oxime rearrangement (Beckmann rearrangement) reaction proceeds.

That is, the present invention relates to the following.

[1] A gas phase reaction in which cyclohexanone oxime is brought into contact with a solid catalyst in the presence of a lower alcohol to convert cyclohexanone oxime to ε-caprolactam, and water, ammonia and amines coexisting in the gas phase reaction system. Adjusting the amount to the following values (1) to (3), wherein the lower alcohol includes a recovered lower alcohol recovered from a reaction mixture obtained by a gas phase reaction: , Ε-caprolactam production method.
(1) 0 ≦ {[ammonia (number of moles) / lower alcohol (number of moles)] × 100} <14
(2) 0 <{[water (number of moles) / lower alcohol (number of moles)] × 100} <11
(3) 0 ≦ {[amines (number of moles) / lower alcohol (number of moles)] × 100} <7.5

[2] The method for producing ε-caprolactam according to [1], wherein the recovered lower alcohol contains distilled lower alcohol, and the distilled lower alcohol is obtained by the following method, wherein the method comprises the gas phase The reaction mixture obtained by the reaction is distilled to separate a gas mainly composed of lower alcohol, and a part of the gas is cooled and condensed to obtain a liquid mixture mainly composed of lower alcohol. Distilling the liquid mixture to obtain a distilled lower alcohol.

[3] The method for producing ε-caprolactam according to [1] or [2], wherein the solid catalyst is zeolite.

[4] Evaporation step of evaporating cyclohexanone oxime in the presence of an inert gas and a lower alcohol to obtain a raw material gas containing cyclohexanone oxime, an inert gas and a lower alcohol; a gas phase reaction in which the raw material gas is brought into contact with a solid catalyst And converting the cyclohexanone oxime into ε-caprolactam to obtain a reaction gas containing ε-caprolactam, a lower alcohol and an inert gas, cooling the reaction gas, and impurities from the reaction solution obtained by cooling A high-boiling component as a first distillation step for obtaining a mixed gas containing ε-caprolactam, a lower alcohol and an inert gas, from the mixed gas, a crude lower alcohol containing a lower alcohol and an inert gas, and ε- Lower alcohol for separating crude ε-caprolactam mixture containing caprolactam Separation step, second distillation step for separating low boiling point component and high boiling point component as impurities from the crude ε-caprolactam mixture to obtain ε-caprolactam, and purifying and collecting a part or all of the crude lower alcohol A method for producing ε-caprolactam including a lower alcohol recovery step for obtaining a lower alcohol, wherein the amount of water, ammonia and amines coexisting in the gas phase reaction system is as follows: A method for producing ε-caprolactam, further comprising adjusting the value to (3).
(1) 0 ≦ {[ammonia (number of moles) / lower alcohol (number of moles)] × 100} <14
(2) 0 <{[water (number of moles) / lower alcohol (number of moles)] × 100} <11
(3) 0 ≦ {[amines (number of moles) / lower alcohol (number of moles)] × 100} <7.5

[5] The method for producing ε-caprolactam according to [4], wherein the solid catalyst is zeolite.

Hereinafter, the method for producing ε-caprolactam according to the present invention will be described with reference to the drawings. FIG. 1 is a flowchart showing a production process in a method for producing ε-caprolactam according to an embodiment of the present invention.

In the present embodiment, an evaporation step (1) for evaporating cyclohexanone oxime 7 in the presence of an inert gas 8, a lower alcohol 9 and water 10, and a reaction step (2) for causing cyclohexanone oxime 7 to undergo a Beckmann rearrangement reaction in the presence of a solid catalyst. ), The first distillation step (3) in which the reaction gas 12 is cooled, the high-boiling component 13 is separated from the reaction solution, and a mixed gas 14 of ε-caprolactam, lower alcohol and inert gas is obtained as the distillate, A lower alcohol separation step (4) in which a lower alcohol and an inert gas are separated from the gas 14 to obtain a crude lower alcohol 15 containing an inert gas and a crude ε-caprolactam mixture 18 mainly composed of crude ε-caprolactam. a second distillation step (5) for separating the low boiling point component 20 and the high boiling point component 19 from the ε-caprolactam mixture 18; Lower alcohol recovery step of purifying a part or the total amount of lower alcohol 15 with a (6).
That is, in this embodiment, cyclohexanone oxime is evaporated in the presence of inert gas 8, lower alcohol 9 and water 10 to obtain a raw material gas containing cyclohexanone oxime 7, inert gas 8, lower alcohol 9 and water 10. Evaporation step (1): A gas phase reaction in which the raw material gas is brought into contact with a solid catalyst is performed to convert the cyclohexanone oxime 7 into ε-caprolactam, thereby obtaining a reaction gas 12 containing ε-caprolactam, a lower alcohol and an inert gas. Reaction step (2): The reaction gas 12 is cooled, the high-boiling component 13 as an impurity is separated from the reaction solution obtained by cooling, and a mixed gas 14 containing ε-caprolactam, a lower alcohol and an inert gas is obtained. A first distillation step (3) to be obtained; a crude lower alcohol containing a lower alcohol and an inert gas from the mixed gas 14; And a crude ε-caprolactam mixture 18 containing ε-caprolactam in a lower alcohol separation step (4); from the crude ε-caprolactam mixture 18, a low-boiling component 20 and a high-boiling component 19 as impurities are separated. A second distillation step (5); and a lower alcohol recovery step (6) for purifying a part or all of the crude lower alcohol 15 to obtain a recovered lower alcohol.
In addition, the 2nd distillation process (5) may be comprised from the some distillation process. More specifically, it is as follows.

In the evaporation step (1), cyclohexanone oxime 7, inert gas 8, lower alcohol 9 and water 10 are supplied to the evaporator 1, and cyclohexanone oxime 7 is heated and evaporated in the presence of the lower alcohol 9 and water 10, A raw material gas 11 containing cyclohexanone oxime 7 and lower alcohol 9 and water 10 is obtained. At this time, water can be mixed with cyclohexanone oxime in advance.

Next, in the reaction step (2), the raw material gas 11 obtained in the evaporation step (1) is supplied to the reactor 2, the raw material gas 11 is brought into contact with the solid catalyst, and cyclohexanone oxime is subjected to a Beckmann rearrangement reaction for gas phase reaction. To convert to ε-caprolactam to obtain a reaction gas 12 (hereinafter also referred to as a reaction mixture). The reaction gas 12 includes ε-caprolactam, a lower alcohol, and an inert gas.
In this specification, the gas phase reaction means that cyclohexanone oxime 7 is reacted with a raw material gas containing lower alcohol 9 and water 10 in contact with a solid catalyst, and is a concept different from a liquid phase reaction.

Next, in the first distillation step (3), the reaction gas 12 obtained in the reaction step (2) is supplied to the first distillation column 3 for cooling, and the reaction solution obtained by cooling is used as a high impurity as an impurity. The boiling point component 13 is separated to obtain a mixed gas 14 containing ε-caprolactam, a lower alcohol and an inert gas.
Here, the inert gas includes nitrogen, argon, carbon dioxide and the like.

Next, in the lower alcohol separation step (4), the mixed gas 14 obtained in the first distillation step (3) is supplied to the lower alcohol recovery tower 4, and the crude gas containing the lower alcohol and the inert gas is supplied from the mixed gas 14. Separate the alcohol 15 and the crude ε-caprolactam mixture 18 containing ε-caprolactam. Here, the amount of water contained in the crude lower alcohol 15 containing an inert gas can be adjusted by distillation conditions.

In the second distillation step (5), the crude ε-caprolactam mixture 18 obtained in the lower alcohol separation step (4) is supplied to the second distillation column 5, and the crude ε-caprolactam mixture 18 is reduced as impurities as impurities. The boiling component 20 and the high boiling component 19 are separated to obtain crude ε-caprolactam 21.
Here, the low boiling point component means a component having a boiling point lower than that of ε-caprolactam.
The high boiling point component means a component having a boiling point higher than that of ε-caprolactam.

Furthermore, in the lower alcohol recovery step (6), a part or the whole amount of the crude lower alcohol 15 obtained in the lower alcohol separation step (4) is supplied to the lower alcohol purification device 6 to remove impurities 16 such as ammonia and amines. By removing and purifying, a recovered lower alcohol (purified lower alcohol) 17 containing an inert gas is obtained. The recovered lower alcohol 17 is supplied to the evaporator 1 and reused after the evaporation step (1).

In addition, what is shown in FIG. 1 is an example, and this invention is not limited to what is shown in FIG. Hereinafter, the present invention will be described focusing on a gas phase reaction using a recovered lower alcohol and a solid catalyst in the presence of the lower alcohol.

The solid catalyst is a solid catalyst for producing ε-caprolactam used when cyclohexanone oxime is converted into ε-caprolactam by Beckmann rearrangement reaction in the gas phase. As such a solid catalyst, various types have been conventionally proposed. Among them, zeolite is preferable, pentasil type zeolite is more preferable, and MFI zeolite is particularly preferable.

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 include Be, B, Al, Ti, V, Cr, Fe, Co, Ni, Cu, Zn, Ga, Ge, Zr, Nb, Sb, La, Hf, and Bi. Etc., and two or more of these may be included as necessary. Further, the atomic ratio of silicon to these elements is preferably 50 or more, more preferably 500 or more.

The zeolite is subjected to hydrothermal synthesis using, for example, a silicon compound, a quaternary ammonium compound, water and, if necessary, a metal compound as a raw material, and the obtained crystals are dried and calcined, and then contacted with ammonia or an ammonium salt. It can be suitably prepared by treating and then drying.

The particle size of the solid catalyst is preferably 0.0001 to 5 mm, and more preferably 0.001 to 3 mm. 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. *

The lower alcohol preferably has 6 or less carbon atoms, specifically, 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. Among these, methanol, ethanol, 1-propanol, 2-propanol, and 1-butanol are preferable, and methanol and ethanol are more preferable because they are particularly excellent in improving selectivity of ε-caprolactam and catalyst life. Methanol and ethanol are most preferable from an industrial viewpoint.
Here, the selectivity means the production rate of ε-caprolactam in the reaction product.

The lower alcohol to be coexistent may be one kind or two or more kinds. In the case of two or more kinds, the combination and ratio can be arbitrarily selected. However, in consideration of handling properties, the lower alcohol is preferably one kind.

In the present invention, the gas phase reaction is carried out, lower alcohol is recovered from the reaction mixture (for example, reaction gas 12 in FIG. 1) obtained thereby, and this recovered lower alcohol (for example, recovered lower alcohol 17 in FIG. ) Is newly used in the gas phase reaction and reused.
That is, the lower alcohol that coexists in the gas phase reaction includes recovered lower alcohol.
Various kinds of recovered lower alcohols can be used depending on the recovery method, and one kind may be used alone, or two or more kinds may be used in combination. When using 2 or more types together, the combination and ratio can be selected arbitrarily.

As the lower alcohol to be coexisted, only the recovered lower alcohol may be used, or the recovered lower alcohol and the lower alcohol that is not recovered (for example, the lower alcohol 9 in FIG. 1, hereinafter referred to as “non-recovered lower alcohol”). May be used in combination. Although depending on the purity of the recovered lower alcohol, usually, by purifying and using at least a part of the recovered lower alcohol, the amount of impurities can be easily reduced to the target amount with only the recovered lower alcohol. On the other hand, recovered lower alcohols usually have a higher impurity content than non-recovered lower alcohols, and depending on their purity, more purification operations may be required to reduce these impurities. By using a lower alcohol in combination, the amount of impurities during the gas phase reaction can be easily reduced even if the purification operation is omitted or reduced.

The recovered lower alcohol can be obtained, for example, by separating a gas mainly containing the lower alcohol (for example, the crude lower alcohol 15 in FIG. 1) from the reaction mixture of the gas phase reaction. The gas mainly composed of lower alcohol can be separated from the reaction mixture by distillation, for example. Hereinafter, the lower alcohol obtained by distillation is also referred to as distilled lower alcohol 15.
In the gas phase reaction, in the operation mode in which the reaction liquid 12 is continuously withdrawn while the raw material gas 11 is continuously supplied, the recovered lower alcohol or the recovered lower alcohol is previously contained using the same reactor. In a gas phase reaction in which cyclohexanone oxime is contacted with a solid catalyst in the presence of a lower alcohol to convert cyclohexanone oxime into ε-caprolactam, or in another production step of ε-caprolactam, a separate reaction vessel is used to lower alcohol. In the coexistence, it means a gas phase reaction in which cyclohexanone oxime is contacted with a solid catalyst to convert cyclohexanone oxime into ε-caprolactam. The separated gas (gas containing a lower alcohol as a main component) may be used as it is, or may be used after partially or fully purifying by a known method. Usually, it is preferable to use after partially purifying.
The gas 15 containing lower alcohol as a main component can be purified by reducing impurities by distillation after being introduced into a gas absorption tower or the like and condensed by cooling, for example. Condensing means that a gas mainly composed of lower alcohol is made into a liquid mixture mainly composed of lower alcohol.
The recovered lower alcohol is preferably used by mixing the crude lower alcohol 15 and the purified lower alcohol 17 obtained by condensation and distillation as described above.
Specifically, the purified lower alcohol is obtained by distilling a reaction mixture obtained by a gas phase reaction, separating a gas containing the lower alcohol as a main component, cooling and condensing a part of the gas, After obtaining the liquid mixture which has a main component, it is preferable to manufacture by the method further including distilling the said liquid mixture and obtaining distilled lower alcohol.

In the present invention, a gas mainly composed of a lower alcohol is separated from the reaction mixture of the gas phase reaction by distillation, and after cooling and condensing a part thereof, the gas obtained by further distillation is obtained. It is preferable to use at least a part of the recovered lower alcohol.

The lower alcohol has a mass ratio to the cyclohexanone oxime (the amount of lower alcohol (mass) / the amount of cyclohexanone oxime (mass)) in the gas phase reaction, preferably 0.1 to 20, more preferably 0.1 to 10. In particular, it is preferable to coexist in the reaction system so as to be 0.3 to 8.

The molar percentage of ammonia (a) ([ammonia (number of moles) / lower alcohol (number of moles)] × 100) in the reaction system during the gas phase reaction is 0 or more and less than 14, and 13 or less. Is preferred.

The mole percentage (b) of water ([water (number of moles) / lower alcohol (number of moles)] × 100) in the reaction system during the gas phase reaction is greater than 0 and less than 11, and 10 or less. It is preferable.
Further, water is a necessary component for smoothly proceeding the rearrangement reaction. From such a viewpoint, the amount of water in the reaction system during the gas phase reaction is preferably 0.06 mol or more with respect to 1 mol of cyclohexanone oxime.

The amines are those in which a hydrogen atom of ammonia (NH ₃ ) is substituted with a hydrocarbon group, and may be any of primary amines, secondary amines and tertiary amines, and any of monoamines and polyamines. Good. Representative amines include monomethylamine for primary amines, dimethylamine for secondary amines, and trimethylamine for tertiary amines.
Here, ammonia is produced at the time of hydrolysis of cyclohexanone oxime, and amines are expected to react with ammonia and lower alcohols.

The mole percentage (c) of amines ([amines (number of moles) / lower alcohol (number of moles)] × 100) in the reaction system during the gas phase reaction is 0 or more and less than 7.5, 7 The following is preferable.

As a main contamination source of water, ammonia and amines, recovered lower alcohol can be exemplified. Therefore, the amount of water, ammonia and amines in the reaction system can be easily adjusted by adjusting the amount or purity of the recovered lower alcohol.
For example, the mixing ratio of recovered lower alcohol and non-recovered lower alcohol (recovered lower alcohol (mass%): non-recovered lower alcohol (mass%)) is preferably 10: 0 to 10:10, and 10: 0 to 10: 2 is more preferable.
In addition, as a method for adjusting the amounts of water, ammonia and amines, in the gas phase reaction, the gas of non-recovered lower alcohol is appropriately supplied into the reaction system while detecting the amounts of water, ammonia and amines. The method of adjusting the quantity of water, ammonia, and amines etc. is mentioned.
The amount of water can be measured by a known method such as the Karl Fischer method, and the amounts of ammonia and amines can be measured by an ion chromatography method.

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 is preferably outside the explosion composition range.

The amount of molecular oxygen in the reaction system during the gas phase reaction is preferably 0.1 to 10 mol, more preferably 0.3 to 5 mol, per 1 mol of cyclohexanone oxime.

The gas phase reaction can be carried out by a normal fixed bed type, fluidized bed type or moving bed type gas phase contact reaction. The raw material cyclohexanone oxime reacts when brought into contact with the catalyst layer in a gaseous state, but the lower alcohol may be preliminarily mixed with cyclohexanone oxime in the gaseous state, or the cyclohexanone oxime is supplied separately to the reactor. May be. In the case of a fixed bed system, it is preferable to pass through the catalyst layer in a state where cyclohexanone oxime and lower alcohol are sufficiently mixed. On the other hand, in the case of a fluidized bed system, it is not always necessary to mix cyclohexanone oxime and lower alcohol in advance, and these may be supplied separately to the reactor, and further divided into lower alcohols. You may supply. In the case of a fluidized bed system, 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 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 in the presence of an inert gas such as nitrogen or carbon dioxide. May be.

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 particularly preferably 300 to 400 ° C. By setting it to the lower limit value or more, the reaction rate is improved, and the selectivity for ε-caprolactam is further improved.
In addition, by making the amount lower than the upper limit value, thermal decomposition of cyclohexanone oxime is suppressed, and the selectivity of ε-caprolactam is further improved.

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 catalyst is 0.1 to 40 kg / h), More preferably, it is 2 to 20 h ⁻¹ , and particularly preferably 0.5 to 10 h ⁻¹ .

The ε-caprolactam produced by the gas phase reaction (rearrangement 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, whereby purified ε-caprolactam is obtained.

The solid catalyst can remove and burn (burn) the carbonaceous material adhering in the gas phase reaction at a temperature of 200 to 600 ° C. with an oxygen-containing gas. it can. The carbonaceous material may be removed in the presence of alcohol in an oxygen-containing gas.

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

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

The present invention is premised on the reuse of the recovered product from the reaction product of the rearrangement reaction as a raw material for the rearrangement reaction of cyclohexanone oxime. Then, paying attention to the impurities that can occur in the rearrangement reaction of cyclohexanone oxime, ammonia, water, and amines are identified as impurities that can inhibit this rearrangement reaction when they are excessively present, and the amount mixed in these reaction systems Are all limited to a limited range. The conventional method for producing ε-caprolactam in which the rearrangement reaction of cyclohexanone oxime is carried out is industrially excellent in terms of high yield. According to the present invention, the reaction rate in the rearrangement reaction of cyclohexanone oxime and Since the selectivity can be maintained at a very high level and the catalyst can be reused, the yield of ε-caprolactam can be further improved and the cost can be reduced.

Hereinafter, the present invention will be described in more detail with reference to specific examples. However, the present invention is not limited to the following examples.
In the following, the space velocity WHSV (h ⁻¹ ) was calculated by dividing the cyclohexanone oxime supply rate (g / h) by the catalyst weight (g). In addition, analysis of cyclohexanone oxime and ε-caprolactam was performed by gas chromatography. The reaction rate of cyclohexanone oxime and the selectivity of ε-caprolactam were the number of moles of cyclohexanone oxime supplied, and the number of moles of unreacted cyclohexanone oxime. Where Y is Y, and the number of moles of ε-caprolactam produced is Z, respectively, and was calculated by the following equations.
Reaction rate of cyclohexanone oxime (%) = [(XY) / X] × 100
Selectivity of ε-caprolactam (%) = [Z / (XY)] × 100

[Example 1]
0.75 g of a silica glass reaction tube having an inner diameter of 1 cm is packed as a solid catalyst with particles having a particle size of 0.3 mm or less mainly composed of crystalline silica MFI zeolite (Si / Al atomic ratio: 147000). Then, a catalyst layer was formed and pre-heated at 340 ° C. for 1 hour under a nitrogen gas flow of 0.72 L / h. Next, under a nitrogen gas flow at 0.72 L / h, a mixture of methanol / cyclohexanone oxime = 1.3 / 1 (mass ratio) was supplied at a feed rate of 6.9 g / h (WHHS of cyclohexanone oxime was 4 h ⁻¹ ). Then, the reaction was carried out for 10 hours while maintaining the temperature of the catalyst layer at 380 ° C. The amount of impurities in the reaction system at this time was made to satisfy the following relationship.
(A) [ammonia (number of moles) / methanol (number of moles)] × 100 = 0
(B) [water (number of moles) / methanol (number of moles)] × 100 = 6.4
(C) [Amines (number of moles) / methanol (number of moles)] × 100 = 0

The reaction solution from the start of the reaction to 10 hours was collected, and the reaction rate of cyclohexanone oxime and the selectivity of ε-caprolactam in the reaction solution were calculated. The results are shown in Table 1.
The yield of ε-caprolactam in this example was 94.9%.

[Example 2]
As shown in Table 1, ε-caprolactam was produced in the same manner as in Example 1 except that the molar percentage (a) of ammonia was changed to 5.9 instead of 0.
The yield of ε-caprolactam was 95.0%.

[Example 3]
As shown in Table 1, ε-caprolactam was produced in the same manner as in Example 1 except that the molar percentage (a) of ammonia was changed to 8.7 instead of 0.
The yield of ε-caprolactam was 95.1%.

[Comparative Example 1]
As shown in Table 1, ε-caprolactam was produced in the same manner as in Example 1, except that the molar percentage (a) of ammonia was 18 instead of 0.
The yield of ε-caprolactam was 93.2%.

[Example 4]
Similarly to Example 1, 0.75 g of a solid catalyst was filled in a quartz glass reaction tube having an inner diameter of 1 cm to form a catalyst layer, and 1 at 340 ° C. under nitrogen gas flow at 0.72 L / h. Preheated for hours. Next, under a nitrogen gas flow at 0.72 L / h, a mixture of methanol / cyclohexanone oxime = 1.3 / 1 (mass ratio) was supplied at a feed rate of 6.9 g / h (WHHS of cyclohexanone oxime was 4 h ⁻¹ ). Then, the reaction was carried out for 2 hours while maintaining the temperature of the catalyst layer at 380 ° C. The amount of impurities in the reaction system at this time was made to satisfy the following relationship.
(A) [ammonia (number of moles) / methanol (number of moles)] × 100 = 0
(B) [water (number of moles) / methanol (number of moles)] × 100 = 6.4
(C) [Amines (number of moles) / methanol (number of moles)] × 100 = 0
At the elapse of 2 hours from the start of the reaction, the reaction rate of cyclohexanone oxime and the selectivity of ε-caprolactam were calculated in the same manner as in Example 1.
The yield of ε-caprolactam was 95.6%.

[Example 5]
As shown in Table 1, ε-caprolactam was produced in the same manner as in Example 4 except that the molar percentage (b) of water was changed to 8.3 instead of 6.4.
The yield of ε-caprolactam was 95.3%.

[Comparative Example 2]
As shown in Table 1, ε-caprolactam was produced in the same manner as in Example 4 except that the value of the molar percentage (b) of water was 14 instead of 6.4.
The yield of ε-caprolactam was 94.6%.

[Example 6]
Similarly to Example 1, 0.75 g of a solid catalyst was filled in a quartz glass reaction tube having an inner diameter of 1 cm to form a catalyst layer, and 1 at 340 ° C. under nitrogen gas flow at 0.72 L / h. Preheated for hours. Next, under a nitrogen gas flow at 0.72 L / h, a mixture of methanol / cyclohexanone oxime = 1.3 / 1 (mass ratio) was supplied at a feed rate of 6.9 g / h (WHHS of cyclohexanone oxime was 4 h ⁻¹ ). Then, the reaction was carried out for 2 hours while maintaining the temperature of the catalyst layer at 380 ° C. The amount of impurities in the reaction system at this time was made to satisfy the following relationship.
(A) [ammonia (number of moles) / methanol (number of moles)] × 100 = 0
(B) [water (number of moles) / methanol (number of moles)] × 100 = 6.4
(C) [Amines (number of moles) / methanol (number of moles)] × 100 = 0
At the elapse of 6 hours from the start of the reaction, the reaction rate of cyclohexanone oxime and the selectivity of ε-caprolactam were calculated in the same manner as in Example 1.
The yield of ε-caprolactam was 95.8%.

[Example 7]
As shown in Table 1, ε-caprolactam was produced in the same manner as in Example 6 except that trimethylamine was used as the amine and the molar percentage (c) was 3.6 instead of 0. did.
The yield of ε-caprolactam was 95.6%.

[Comparative Example 3]
As shown in Table 1, ε-caprolactam was produced in the same manner as in Example 6 except that trimethylamine was used as the amine, and the molar percentage (c) was 7.5 instead of 0. did.
The yield of ε-caprolactam was 95.5%.

[Reference Example 1]
A part or all of the distilled lower alcohol obtained in the lower alcohol separation step (4) was cooled to 7 to 30 ° C. and liquefied. The liquefied lower alcohol was distilled under conditions of 80 ° C. and 175 kPaA to obtain recovered lower alcohol 17.
The methanol thus obtained contains 0.49% of water, 0.01% of ammonia, and 1.4% of trimethylamine, and water is added thereto to adjust the water content to 4.0. %. This was mixed with cyclohexanone oxime at 1.3 / 1 (mass ratio) and used for the reaction.
[Example 8]
Similarly to Example 1, 0.75 g of a solid catalyst was filled in a quartz glass reaction tube having an inner diameter of 1 cm to form a catalyst layer, and 1 at 340 ° C. under nitrogen gas flow at 0.72 L / h. Preheated for hours. Subsequently, under a nitrogen gas flow at 0.72 L / h, the mixture of methanol / cyclohexanone oxime = 1.3 / 1 (mass ratio) prepared in Reference Example 1 was added to 6.9 g / h (the WHSV of cyclohexanone oxime was 4 h). ^-1 ) was supplied to the reaction tube at a supply rate, and the reaction was carried out for 10 hours while maintaining the temperature of the catalyst layer at 380 ° C. And the amount of impurities in the reaction system at this time satisfied the following relationship.
(A) [ammonia (number of moles) / methanol (number of moles)] × 100 = 0.02
(B) [water (number of moles) / methanol (number of moles)] × 100 = 7.2
(C) [Amines (number of moles) / methanol (number of moles)] × 100 = 0.77
The reaction solution from the start of the reaction until 10 hours was collected, and the reaction rate of cyclohexanone oxime and the selectivity of ε-caprolactam were calculated in the same manner as in Example 1.
The yield of ε-caprolactam was 95.3%.

The following points were confirmed from the above results.
In Examples 1 to 7, the selectivity and the reaction rate were both high, and the catalytic activity was also good.
On the other hand, when the value of the molar percentage (a) of ammonia was increased, in Comparative Example 1, although the reaction rate was good, the selectivity was lower than in Examples 1 to 3 and the yield was lowered.
In addition, the value of the molar percentage (b) of water increased, and in Comparative Example 2, although the reaction rate was good, the selectivity was lower than in Examples 4-5.
Further, the value of the mole percentage (c) of the amines was increased, so that in Comparative Example 3, although the reaction rate was good, the selectivity was lower than in Examples 6-7.
As described above, ammonia, water and amines are selected as impurities that define the amount of contamination in the reaction system, and by limiting these amounts to a limited range, the reaction in the cyclohexanone oxime rearrangement reaction It was confirmed that the rate and selectivity can be maintained at a very high level.

The present invention can be used for the production of ε-caprolactam by a gas phase reaction using a solid catalyst.
ADVANTAGE OF THE INVENTION According to this invention, the manufacturing method of the epsilon caprolactam excellent in the selectivity in the rearrangement reaction of cyclohexanone oxime can be provided.
Further, by reusing the recovered lower alcohol, the amount of industrial waste can be reduced, and the burden on the environment can be reduced.

DESCRIPTION OF SYMBOLS 1 ... Evaporator, 2 ... Reactor, 3 ... 1st distillation tower, 4 ... Lower alcohol recovery tower, 5 ... 2nd distillation tower, 6 ... Lower alcohol refiner | purifier, 7 ... cyclohexanone oxime, 8 ... inert gas, 9 ... lower alcohol, 10 ... water, 11 ... raw material gas, 12 ... reactive gas, 13 ... high boiling point component, 14 ... ε-caprolactam, mixed gas of lower alcohol and inert gas, 15 ... crude lower alcohol (including inert gas), 16 ... impurities such as ammonia and amines, 17 ... purification Lower alcohol (recovered lower alcohol, including inert gas), 18 ... crude ε-caprolactam mixture, 19 ... high boiling component, 20 ... low boiling component, 21 ... crude ε-caprolactam

Claims

Performing a gas phase reaction in which cyclohexanone oxime is contacted with a solid catalyst in the presence of a lower alcohol to convert cyclohexanone oxime to ε-caprolactam; and
Adjusting the amounts of water, ammonia and amines coexisting in the gas phase reaction system to the values of (1) to (3) below,
The method for producing ε-caprolactam, wherein the lower alcohol includes a recovered lower alcohol recovered from a reaction mixture obtained by a gas phase reaction.
(1) 0 ≦ {[ammonia (number of moles) / lower alcohol (number of moles)] × 100} <14
(2) 0 <{[water (number of moles) / lower alcohol (number of moles)] × 100} <11
(3) 0 ≦ {[amines (number of moles) / lower alcohol (number of moles)] × 100} <7.5
The recovered lower alcohol comprises distilled lower alcohol;
The method for producing ε-caprolactam according to claim 1, wherein the distilled lower alcohol is obtained by the following method.
In the method, the reaction mixture obtained by the gas phase reaction is distilled to separate a gas mainly containing a lower alcohol, and a part of the gas is cooled and condensed to obtain a liquid mainly containing a lower alcohol. After obtaining the mixture, the method further includes distilling the liquid mixture to obtain a distilled lower alcohol.
The method for producing ε-caprolactam according to claim 1 or 2, wherein the solid catalyst is zeolite.
An evaporation step of evaporating cyclohexanone oxime in the presence of an inert gas and a lower alcohol to obtain a raw material gas containing cyclohexanone oxime, the inert gas and the lower alcohol;
Performing a gas phase reaction in which the raw material gas is brought into contact with a solid catalyst, converting the cyclohexanone oxime into ε-caprolactam, and obtaining a reaction gas containing ε-caprolactam, a lower alcohol and an inert gas;
A first distillation step of cooling the reaction gas, separating a high-boiling component as an impurity from the reaction solution obtained by cooling, and obtaining a mixed gas containing ε-caprolactam, a lower alcohol and an inert gas;
A lower alcohol separation step for separating a crude lower alcohol containing a lower alcohol and an inert gas and a crude ε-caprolactam mixture containing ε-caprolactam from the mixed gas;
A low-boiling component and a high-boiling component as impurities are separated from the crude ε-caprolactam mixture, a second distillation step for obtaining ε-caprolactam, and a part or all of the crude lower alcohol is purified to recover the recovered lower alcohol. A process for producing ε-caprolactam including a lower alcohol recovery step to be obtained,
The method for producing ε-caprolactam further comprises adjusting the amounts of water, ammonia and amines coexisting in the gas phase reaction system to the following values (1) to (3): .
(1) 0 ≦ {[ammonia (number of moles) / lower alcohol (number of moles)] × 100} <14
(2) 0 <{[water (number of moles) / lower alcohol (number of moles)] × 100} <11
(3) 0 ≦ {[amines (number of moles) / lower alcohol (number of moles)] × 100} <7.5
The method for producing ε-caprolactam according to claim 4, wherein the solid catalyst is zeolite.