JP3254752B2 - Production method of 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 ε-Caprolactam is an important basic chemical raw material used as a raw material for nylon and the like.

The present inventors have proposed a method for producing ε-caprolactam by rearranging cyclohexanone oxime (Beckmann rearrangement) under gas phase reaction conditions using a solid catalyst (Japanese Patent Application Laid-Open No. 2-275850). And JP-A-2-250866.

The inventors of the present invention have conducted further intensive studies on the rearrangement reaction of cyclohexanone oxime using a solid catalyst. The catalyst life is improved,
Further, they have found that the yield of ε-caprolactam is improved, and have completed the present invention.

[0005]

That is, the present invention is characterized in that a cyclohexanone oxime is contact-reacted in a gas phase by using a zeolite catalyst in the presence of an alcohol and / or an ether compound and further coexisting water in a reaction system. To provide an industrially excellent method for producing ε-caprolactam.

Hereinafter, the present invention will be described in detail. Examples of the zeolite catalyst used in the present invention include crystalline silica and crystalline metallosilicate.

[0007] The crystalline silica in the present invention is substantially composed of silicon and oxygen, and the crystalline metallosilicate is a substance containing a metal in addition to silicon and oxygen. The ratio of the number of silicon atoms to the number (Si / Me atomic ratio) is 5 or more, preferably 500 or more. Here, as the metal, Al, Ga,
Fe, B, Zn, Cr, Be, Co, La, Ge, T
One or more metals selected from i, Zr, Hf, V, Ni, Sb, Bi, Cu, Nb, and the like. Si / Me
The atomic ratio can be determined by ordinary analysis means, for example, an atomic absorption method, a fluorescent X-ray method, or the like.

[0008] These catalysts can be produced by a known method. Various crystalline types are known for these crystalline silicas and crystalline metallosilicates, and those belonging to a so-called pentasil type structure are preferable.

The present invention is characterized in that water is allowed to coexist in the reaction system. The amount of such water is 0.06 to 2.5 times, preferably 0. .18 to 1.9 times, more preferably 0.18 to 0.6
5 times. Water is 0,0 for cyclohexanone oxime.
If it is less than 06 times or more than 2.5 times, the activity of the catalyst is greatly reduced, which is not preferable.

In the present invention, an alcohol or an ether compound is co-present with water in the reaction system. Examples of such alcohol and ether compounds include compounds represented by the following general formula (1). R ₁ —O—R ₂ (1) (wherein, R ₁ represents a lower alkyl group optionally substituted with a fluorine atom, and R ₂ represents a lower alkyl group optionally substituted with a hydrogen atom or a fluorine atom. Or a phenyl group.) Specific examples of the alcohol include, for example, methanol, ethanol, n-propanol, isopropanol, n-butanol, sec-butanol, isobutanol, n-amyl alcohol, n-hexanol,
Examples thereof include lower alcohols having 6 or less carbon atoms such as 2,2-trifluoroethanol, and among them, methanol and ethanol are preferable. As the ether compound to coexist, those in which R ₁ is a methyl group or an ethyl group are preferable, for example, dimethyl ether, methyl ethyl ether,
Examples thereof include ether compounds having 8 or less carbon atoms such as diethyl ether, methyl-n-propyl ether, methyl isopropyl ether, methyl-tert-butyl ether, and anisole. Two or more of these alcohol and ether compounds can be used in combination, and an alcohol and an ether compound can be used in combination.

Furthermore, in the present invention, a vapor of a compound inert to the reaction such as benzene, cyclohexane, toluene or the like, or an inert gas such as nitrogen or carbon dioxide can be coexisted in the reaction system as a diluent gas.

Next, a reaction method for carrying out the present invention will be described. The starting material cyclohexanone oxime is brought into contact in a gaseous state, and the reaction may be carried out in any of a fixed bed system and a fluidized bed system. Water, alcohol, ether compound, etc. may be mixed with cyclohexanone oxime in advance and supplied to the reactor, or may be supplied separately from cyclohexanone oxime. In the latter case, water or the like can be supplied separately. In the case of the fixed bed system, it is preferable that cyclohexanone oxime is sufficiently mixed with water, alcohol, ether compound and the like to pass through the catalyst layer.

Space velocity of raw material cyclohexanone oxime
The degree is usually WHSV = 0.1-40hr ^-1(That is, catalyst 1
Cyclohexanone oxime feed rate per kg is 0.1 ~
40 kg / hr), preferably 0.2 to 20 hr.^-1,Than
Preferably 0.5 to 10 hours^-1Is selected from the range.

The reaction temperature of the present invention is usually from 250 to 500 ° C.
However, it is preferably from 300 to 450 ° C, more preferably from 300 to 400 ° C. If the temperature is lower than 250 ° C., the reaction rate is not sufficient, and the selectivity of ε-caprolactam tends to decrease, while if it exceeds 500 ° C., the selectivity of ε-caprolactam tends to decrease.

Further, the present invention can be carried out under any of pressurized, normal pressure and reduced pressure.
The reaction is carried out under a reaction condition of 10 kg / cm ² .

The separation and purification of ε-caprolactam from the reaction mixture can be carried out, for example, by cooling and condensing the reaction product gas, followed by extraction, distillation or crystallization.

The catalyst whose activity has been reduced over a long period of use can be easily prepared by calcining in a molecular oxygen-containing gas, for example, in a stream of air, or calcining in a molecular oxygen-containing gas to which alcohol has been added. Can be activated to the original performance,
Can be used repeatedly.

[0018]

According to the present invention, the life of the catalyst is remarkably improved, and the yield of ε-caprolactam is improved.

[0019]

EXAMPLES The present invention will now be described specifically with reference to examples, but the present invention is not limited to these examples.

REFERENCE EXAMPLE 1 (Preparation of catalyst) Tetraethyl orthosilicate (Si (OC ₂ H ₅ ) ₄ , Al content 10 ppm or less) was placed in a 1.5-liter stainless steel autoclave.
100 g, 224.0 g of a 10% aqueous solution of tetra-n-propylammonium hydroxide, and 214 g of ethanol.
Stir vigorously for 0 minutes. The pH of the mixed solution was 13. After closing the autoclave lid, it was immersed in an oil bath to maintain the internal temperature at 105 ° C., and 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. The white solid product was filtered off and washed successively with distilled water until the pH of the washings was around 7. After drying the white solid, 530
C. for 4 hours to obtain 27 g of 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 the atomic absorption method, the Al content was 3 ppm. This crystal 10
100 g of a 5% aqueous solution of ammonium chloride,
After performing an ion exchange treatment at ６０60 ° C. for 1 hour, the crystals were separated by filtration. After performing this ion exchange treatment operation four times, the crystals were washed with distilled water until no Cl ^- ions were detected in the washing solution. Subsequently, the crystal was dried at 120 ° C. for 16 hours, and the obtained ammonium salt type crystal was subjected to pressure molding.
It was sieved to 4-48 mesh. Further, the crystals were calcined at 500 ° C. for 1 hour under flowing nitrogen gas to obtain a catalyst.

Example 1 0.375 g (0.6 ml) of the catalyst prepared in Reference Example 1 was charged into a quartz glass reaction tube having an inner diameter of 1 cm, and the reaction mixture was placed under a nitrogen stream (4.2).
1 / hr) at 350 ° C. for 1 hour. Then, the molar ratio of cyclohexanone oxime / methanol / water was 1 /
A mixed solution of 6.4 / 0.31 was supplied to the reaction tube at a rate of 8.58 g / hr to cause a reaction. At this time, 0.21 l / hr of ammonia gas and 3.99 of nitrogen gas were used as carrier gases.
It was fed at a rate of 1 / hr. At this time, the space velocity WHSV of cyclohexanone oxime was 8 hr ^-1 and the temperature (reaction temperature) of the catalyst layer was 380 ° C. The reaction product was collected under water cooling and analyzed by gas chromatography. Table 1 shows the reaction results.

Here, the space velocity WHSV of cyclohexanone oxime was calculated by the following equation, and the conversion of cyclohexanone oxime and the selectivity of ε-caprolactam were also calculated by the following equation. WHSV (hr ^-1 ) = O / C Conversion of cyclohexanone oxime (%) = [(XY) / X] × 100 Selectivity (%) of ε-caprolactam = [Z / (XY)] × 100 In addition, 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

[0023]

[Table 1]

Example 2 A mixed solution of cyclohexanone oxime / methanol / water having a molar ratio of 1 / 6.4 / 0.1 was treated at a rate of 8.48 g / hr (WH
The reaction was carried out under the same conditions as in Example 1 except that the reaction mixture was supplied to the reaction tube at SV = 8 hr ^-1 ). Table 2 shows the reaction results.

[0025]

[Table 2]

Example 3 A mixed solution having a molar ratio of cyclohexanone oxime / methanol / water of 1 / 6.4 / 0.63 was heated at a rate of 8.73 g / hr (W
The reaction was carried out under the same conditions as in Example 1 except that the reaction tube was fed at HSV = 8 hr ^-1 ). Table 3 shows the reaction results.

[0027]

[Table 3]

Example 4 A mixed solution having a molar ratio of cyclohexanone oxime / methanol / water of 1 / 6.4 / 1.89 was dissolved at a rate of 9.33 g / hr (W
The reaction was carried out under the same conditions as in Example 1 except that the reaction tube was fed at HSV = 8 hr ^-1 ). Table 4 shows the reaction results.

[0029]

[Table 4]

Comparative Example 1 The weight ratio of cyclohexanone oxime / methanol was 1 /
The mixed solution of 1.8 was fed at a rate of 8.44 g / hr (WHSV = 8 hr).
^The reaction was carried out under the same conditions as in Example 1 except that the mixture was supplied to the reaction tube in ^-1 ). Table 5 shows the reaction results. The amount of water in cyclohexanone oxime used as a reaction raw material was analyzed to be 0.3% by weight, which was 0.019 mol per mol of cyclohexanone oxime.

[0031]

[Table 5]

Comparative Example 2 (Application to Boric Acid Catalyst) In Example 1, the catalyst prepared in Reference Example 1 was replaced with boric acid 0.3.
The reaction was carried out under the same conditions as in Example 1 except that the amount was changed to 75 g. Immediately after the start of the reaction, boric acid was eluted, and substantially no reaction was performed.

──────────────────────────────────────────────────続 き Continuation of the front page (56) References JP-A-2-275850 (JP, A) JP-A-2-250866 (JP, A) JP-A-53-37684 (JP, A) 5257 (JP, B1) JP-B-48-39952 (JP, B1) JP-B-49-42594 (JP, B1) JP-B, 50-20074 (JP, B1) JP-B, 45-2383 (JP, B1) JP-B-46-32275 (JP, B1) JP-B-48-10478 (JP, B1) JP-B-46-23745 (JP, B1) (58) Fields investigated (Int. Cl. ⁷ , DB name) C07D 201/04

Claims (1)

(57) [Claims] (1) A zeolite catalyst is used in the presence of an alcohol and / or an ether compound, and water is added to the reaction system in the range of from 0.06 to 2.5 mol per mol of cyclohexanone oxime. A process for producing ε-caprolactam, which comprises reacting an oxime with a catalyst.