JPH02250866A - Production of epsilon-caprolactam - Google Patents

Abstract

PURPOSE:To readily obtain the subject compound useful as a now material for nylon, etc., in a high selectivity in the elongated life of a catalyst by reacting cyclohexanone oxime in the presence of a solid acid catalyst and in the coexistence of an ether compound under a gaseous reaction condition. CONSTITUTION:Cyclohexanone oxime is subjected to a gaseous phase rearrangement reaction in the presence of a solid acid catalyst, especially a silicon oxide- containing catalyst such as crystalline aluminosilicate having a Si/Al atom ratio of >=5, preferably in a weight ratio of 0.3-15 times the weight of the cyclohexanone oxime in the coexistence of an ether compound of a formula: R1-O-R2 (R1 is CH3 or C2H5; R2 is 1-6C alkyl or phenyl) such as methyl tertbutyl ether, diethyl ether or anisole and, if necessary, a diluting gas such as benzene especially preferably at 300-450 deg.C preferably at a feeding rate of LHSV=0.2-20 hr<-1> to provide the objective compound. The ether compound is separated and recovered for the re-use thereof.

Description

DETAILED DESCRIPTION OF THE INVENTION <Industrial Application Field> The present invention relates to a method for producing ε-caprolactam from cyclohexanone oxime under gas phase reaction conditions using a solid acid catalyst.

<Prior art and problems to be solved by the invention> ε-caprolactam is an important basic chemical raw material used as a raw material for nylon, etc., and its manufacturing method has conventionally used fuming sulfuric acid or concentrated sulfuric acid as a catalyst. A method has been adopted in which cyclohexanone oxime is rearranged under the liquid phase.

However, this method not only requires a large amount of fuming sulfuric acid, but also has the problem of producing a large amount of ammonium sulfate as a by-product.

On the other hand, various methods have been proposed to solve mB such as using a solid acid catalyst and rearranging it in the gas phase. Publication No. 831.927), silica-alumina catalyst (British Patent No. 831.927), solid phosphoric acid catalyst (
British Patent No. 881.926), composite metal oxide catalyst (
Journal of the Chemical Society of Japan, 1977, (1) 77), Zeolite Catalysts (Journal of Catalysis)
6.247 (1966), JP-A-57-139062
There is a method using the following. However, both methods have problems in terms of reaction selectivity of the target ε-caprolactam, catalyst life, productivity per catalyst, and quality of the product ε-caprolactam. l! has a problem.

For example, JP-A-57-139062 discloses a specific example of using crystalline zeolite such as ZSM-5 having a Sl/Al atomic ratio of 40 to 60 as a catalyst, and states that the reaction rate of cyclohexanone oxime is quantitative. However, there is no mention of the selectivity of and-caprolactam, and the results show that the catalyst life is as short as 15 to 20 hours.

The present inventors also used Sl/Al as described in the publication.
Although ZSM-5 zeolite with an atomic ratio was actually investigated as a catalyst, not only the life of the catalyst but also the selectivity to ε-caprolactam were found to be insufficient.

On the other hand, JP-A-62-123167, JP-A-63-
Publication No. 54358 discloses that a crystalline aluminosilicate with an Si/Al atomic ratio of 500 or more and an amount of acid outside the pores below a specific value, or a crystalline metallosilicate with a Si/metal atomic ratio of 500 or more is used as a catalyst. , an example is shown. The selectivity of this product is considerably improved compared to conventional silica-based catalyst technology, and is further improved in JP-A No. 62-281.
No. 856 discloses that the selectivity can be improved by treating the surface of crystalline zeolite with an organometallic compound.

Means for Solving the Problems> In view of the current situation, the present inventors have proceeded with the study of a gas phase Beckmann rearrangement reaction using a solid acid catalyst, which is superior to the conventional method. By allowing an ether compound to coexist with xanone oxime, the reaction rate of cyclohexanone oxime can be reduced to, for example, substantially 100%.
%, it was found that 2-caprolactam can be obtained with extremely high selectivity, and the life of the catalyst is significantly improved, and the present invention has been completed.

That is, the present invention provides a method for producing ε-caprolactam from cyclohexanone oxime using a solid acid catalyst, which is characterized in that an ether compound is allowed to coexist in the reaction system. be.

The present invention will be explained in detail below.

In the present invention, conventionally used solid acids can be used as catalysts. Among solid acids, silicon oxide-containing catalysts, particularly crystalline aluminosilicates or crystalline metallosilicates, are preferable, particularly crystalline aluminosilicates with an Si/Al atomic ratio of 5 or more or a Si/Me atomic ratio (where Me is Ga , Fe, B, Zn, Cr, Be, Co,
La.

Ti, Zr, If, V, Ni, Sb, Bi, Cu.

A crystalline metallosilicate in which one or more metal elements selected from Nb etc.) is 5 or more is more preferable. The Si/Al atomic ratio and the Si/Me atomic ratio can be determined by conventional analytical means, such as atomic absorption spectrometry, fluorescent X-ray analysis, and the like.

Moreover, these catalysts are manufactured by known methods. Although various crystal forms are known for such crystalline aluminosilicate or crystalline metallosilicate, those belonging to the so-called pentasil structure are particularly preferred.

In the present invention, an ether compound is allowed to coexist with cyclohexanone oxime in the reaction system, and the ether compound used here is preferably an ether represented by the following general formula.

R, -0-R.

Here, R7 is a methyl group or an ethyl group, and R2 is an alkyl group having 1 to 6 carbon atoms or a phenyl group.

Specifically, dimethyl ether, methyl ethyl ether,
It is recommended to use one or more of diethyl ether, methyl-n-propyl ether, methyl isopropyl ether, methyl-tar t-butyl ether, anisole, and the like. In particular, it is more preferable to use one or more ether compounds in which R8 is a methyl group, as this is highly effective in improving the selectivity of ε-caprolactam and catalyst life.

Next, a reaction method for carrying out the present invention will be described.

The reaction is carried out in a gas phase contact reaction using a normal fixed bed or fluidized bed method.The raw material cyclohexanone oxime reacts with the catalyst layer in a gaseous state, but the ether compound is premixed with the cyclohexanone oxime in a gaseous state. In the case of a fixed bed reaction, it is preferable that the cyclohexanone oxime and the ether compound pass through the catalyst bed in a well-mixed state; In this case, the cyclohexanone oxime and the ether compound do not necessarily need to be mixed in advance, and can be supplied separately, and the ether compound can also be added in portions. Furthermore, in the case of a fluidized bed reaction, an ether compound may be added upstream of the cyclohexanone oxime.

The appropriate amount of the ether compound to coexist in the reaction system is usually 0.1 to 20 times the weight of cyclohexanone oxime, and if it is less than 0.1 times, the effect of adding the ether compound will be negligible. Therefore, addition of an ether compound in an amount exceeding 20 times is not only uneconomical but also generally undesirable because it lowers the reaction rate of cyclohexanone oxime, increases the selectivity of ε-caprolactam, and increases the catalyst For the purpose of improving the lifespan, the amount of the ether compound coexisting is usually 0% by weight relative to cyclohexanone oxime.
．． A range of 3 to 15 times is preferred.

Benzene, cyclohexane,
The vapor of a compound inert to the reaction, such as toluene, or an inert gas, such as nitrogen or carbon dioxide, may also be coexisting.

The reaction temperature is usually in the range of 250°C to 500°C. 2
At temperatures below 50°C, the reaction rate is insufficient and ε-
The selectivity of caprolactam also tends to be low. on the other hand,
When the temperature exceeds 500°C, the thermal decomposition of cyclohexanone oxime cannot be ignored, and the selectivity of ε-caprolactam decreases. Particularly preferable temperature range is 300℃~450℃
℃, and the most preferable temperature range is 300℃~400℃
It is.

The feed rate of raw material cyclohexanone oxime is usually LH
3V=0.1~40hr-' (i.e. catalyst 1ffi
Cyclohexanone oxime supply rate per unit: 0.1-40
1/hour). Preferably 0.2~20hr-
', more preferably selected from the range of 0.5 to 10 hr-'.

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

The ether compound added to the rearrangement reaction system can be separated and recovered from the reaction product and reused.

Further, a catalyst whose activity has decreased due to long-term use can be easily reactivated to its original performance by firing in a stream of air, and can be used repeatedly.

<Effects of the Invention> As detailed above, according to the present invention, ε-caprolactam can be produced with extremely high selectivity even under conditions where the reaction rate of cyclohexanone oxime is substantially around 100%. Also, in the process of the present invention, the lifetime of the catalyst is significantly improved compared to conventional processes. Furthermore, the ether compound added to the reaction system can be recovered and reused.The method of the present invention has many advantages over conventionally known methods, and therefore has great industrial value.

<Examples> The present invention will be specifically described below with reference to Examples, but the present invention is not limited thereto.

Reference example (preparation of catalyst) Tetraethyl orthosilicate (S i (OC*Hs) 4) 10
0 g of 10% tetra-n-propylammonium hydroxide aqueous solution Wi, and 60 g of ethanol were charged and thoroughly stirred. Add 48 g of aluminum sulfate aqueous solution (Al proverb (SO4)!・16HIO
20 ml/48 g of water) was added and stirred vigorously for 30 minutes.

Note that the pH of the mixed solution was 13. After tightening the lid of the autoclave, immerse it in an oil bath and keep the internal temperature at 105℃ at 400℃.
r.

Hydrothermal synthesis was carried out for 120 hours while stirring at rotational speeds of 1, 2, m or more. During this time, the pressure inside the autoclave reached 2 kg/cj to 3 kg/c-. The pH at the end of the hydrothermal synthesis was 11.8. The white solid product was calcined in the same manner as in Reference Example 1 to obtain powdery white crystals.

As a result of analyzing the crystals by powder X-ray diffraction, they were identified as pentasil type zeolite. Further, as a result of elemental analysis by atomic absorption spectroscopy, the Si/A satoatomic ratio was 7,000.

100g of 5% ammonium chloride aqueous solution to 10g of this crystal
was added and subjected to ion exchange treatment at 50 to 60°C for 1 hour, followed by filtration. After performing this ion exchange treatment four times, the crystals were washed with distilled water until no 01- ions were detected. Subsequently, the crystals were dried at 120°C for 16 hours. The obtained ammonium salt type crystals were pressure-molded and then sieved into 24 to 48 meshes. Further, the crystals were calcined at 500°C for 1 hour under nitrogen gas flow to obtain a catalyst.

Example 1 0.3 g of catalyst was placed in a quartz glass reaction tube with an inner diameter of 1 cm.
(0.5 m) was filled and preheated at 350°C for 1 hour under a nitrogen stream. Then cyclohexanone oxime/methyl-tert-butyl ether/benzene weight ratio -1/
A mixed solution of 3.1/10.6 was supplied to the reaction tube at a supply rate of 11.5 g/hr and reacted. Space velocity W at this time
/F was 42.5 g-hr/mole, and the temperature of the catalyst layer (reaction temperature) was 350°C.The reaction product was collected every hour under water cooling and analyzed by gas chromatography.

The analysis results are shown in Table 1.

Table 1 Here, the space velocity W/F is a value calculated using the following equation, and the reaction rate of cyclohexanone oxime and the selectivity of ε-caprolactam were calculated using the following equations.

W/F (g hr/mole) Reaction rate of cyclohexanone oxime (%) - ((X-Y)/X
i xlOO ε-Caprolactam selectivity (%) - (Z/ (X-Y))xt o.

Yield of ε-caprolactam (%) =Z/Xx 100 In addition, X, Y, and Z are as follows, respectively.

X - Number of moles of supplied raw material cyclohexanone oxime Y = Number of moles of unreacted cyclohexanone oxime 2 = Number of moles of ε-caprolactam in the product Comparative example Same method as Example 1 except that a mixed solution of hexanone oxime/benzene weight ratio = 1/11°5 was supplied to the reaction tube at a supply rate of 11.5 g/hr (W/F = 36.8). I did it.

The reaction results are shown in Table 2.

Table 2 The reaction was carried out in the same manner as in Example 1 at a reaction temperature of 350°C, except that the ether compound shown in Table 3 was used instead of tyl-n-propyl ether, and the raw material composition ratio and raw material supply rate were changed.

The reaction results are shown in Table 3.

Examples 2 to 4 Using the same catalyst as that used in Example 1, procedural amendment (spontaneous) December 22, 1989 1, Description of the case 1999 Patent Application No. 73057 2, Title of the invention ε-Caprolactam manufacturing method 3, relationship with the amended case Patent applicant address 4-5-33 Kitahama, Chuo-ku, Osaka Name (
209) Sumitomo Chemical Co., Ltd. Representative: Hideo Mori 4, Agent address: 4-5-33 Kitahama, Chuo-ku, Osaka, Column 6 of “Detailed Description of the Invention” of the specification to be amended; Contents (1) “Same as Reference Example 1” on page 10, line 18 of the specification
was separated by filtration, and then washed continuously with distilled water until the pH of the filtrate was around 7. After drying, the white solid was 500-530
℃ for 4 hours under air circulation.''

that's all Procedural amendment (voluntary) January 7th, 1990

Claims (1)

[Claims] 1. A method for producing ε-caprolactam from cyclohexanone oxime under gas phase reaction conditions using a solid acid catalyst, the method comprising coexisting an ether compound in the reaction system.