JPH05201965A - Production of epsilon-caprolactam - Google Patents

Abstract

PURPOSE:To provide a process for producing epsilon-caprolactam in improved life of catalyst and yield of epsilon-caprolactam. CONSTITUTION:epsilon-Caprolactam is produced by the catalytic reaction of cyclohexanone oxime in vapor phase using a zeolite catalyst in the presence of an alcohol and/or an ether compound in a reaction system containing 0.06-2.5mol of water based on 1mol of cyclohexanone oxime.

Description

Detailed Description of the Invention

[0001]

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

[0002]

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 and the like.

The present inventors have proposed a method for producing ε-caprolactam by rearrangement (Beckmann rearrangement) of cyclohexanone oxime under a gas phase reaction condition using a solid catalyst (JP-A-2-275850). And JP-A-2-250866).

The inventors of the present invention have conducted further diligent studies on the rearrangement reaction of cyclohexanone oxime using a solid catalyst. As a result, a zeolite catalyst was used in the presence of an alcohol and / or ether compound, and water was allowed to coexist in the reaction system. By improving the life of the catalyst,
Moreover, they found that the yield of ε-caprolactam was improved, and completed the present invention.

[0005]

That is, the present invention is characterized in that a zeolite catalyst is used in the presence of an alcohol and / or ether compound, and water is allowed to coexist in the reaction system to cause cyclohexanone oxime to catalytically react in the gas phase. And an industrially excellent method for producing ε-caprolactam.

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

The crystalline silica in the present invention is substantially composed of silicon and oxygen, and the crystalline metallosilicate is a material containing a metal in addition to silicon and oxygen, such as a metal atom. 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 can be mentioned. Si / Me
The atomic ratio can be determined by a usual analytical means such as an atomic absorption method and a fluorescent X-ray method.

Further, these catalysts can be produced by a known method. Various crystalline forms are known for these crystalline silica and crystalline metallosilicate, but those belonging to the so-called pentasil type structure are preferable.

The present invention is characterized in that water is allowed to coexist in the reaction system, and the amount of such water used is 0.06 to 2.5 times, preferably 0 times, the molar ratio of 1 mol of cyclohexanone oxime. 0.18 to 1.9 times, more preferably 0.18 to 0.6
5 times. Water is 0 for cyclohexanone oxime.
If it is less than 06 times or more than 2.5 times, the activity of the catalyst is largely decreased, which is not preferable.

In the present invention, an alcohol or ether compound is allowed to coexist 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) (In the formula, R ₁ represents a lower alkyl group optionally substituted by a fluorine atom, R ₂ is a hydrogen atom, a lower alkyl group optionally substituted by 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, 2,
Examples thereof include lower alcohols having 6 or less carbon atoms such as 2,2-trifluoroethanol, and among them, methanol and ethanol are preferable. The coexisting ether compound is preferably _{one in} which R ₁ is a methyl group or an ethyl group, such as 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. These alcohol and ether compounds may be used in combination of two or more, and the alcohol and ether compound may be used in combination.

Further, 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 may coexist as a diluent gas in the reaction system.

Next, a reaction method for carrying out the present invention will be described. The cyclohexanone oxime as a raw material is catalytically reacted in a gas state, but the reaction may be carried out by either a fixed bed system or 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 divided and supplied. In the case of the fixed bed system, it is preferable to allow the cyclohexanone oxime to sufficiently pass through the catalyst layer in a state of being sufficiently mixed with water, alcohol, ether compound and the like, and thus the former method is usually adopted.

Space velocity of cyclohexanone oxime as a raw material
Degree is usually WHSV = 0.1-40hr ^-1(Ie catalyst 1
Cyclohexanone oxime supply rate per kg is 0.1-
40 kg / hr), preferably 0.2 to 20 hr^-1,Than
Preferably 0.5-10 hr^-1Selected from the range of.

The reaction temperature of the present invention is usually 250 to 500 ° C.
However, the temperature is preferably 300 to 450 ° C, and more preferably 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 pressure, normal pressure and reduced pressure.
It is carried out under the reaction conditions of 10 kg / cm ² .

Separation and purification of ε-caprolactam from the reaction mixture can be carried out, for example, by cooling the reaction product gas to condense it and then performing extraction, distillation or crystallization.

Further, the catalyst whose activity has been lowered due to long-term use can be easily prepared by calcining in a molecular oxygen-containing gas, for example, in an air stream, or in a molecular oxygen-containing gas to which alcohol is 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 be described in detail below with reference to examples, but the present invention is not limited thereto.

Reference Example 1 (Preparation of catalyst) Tetraethylorthosilicate (Si (OC ₂ H ₅ ) ₄ , Al content 10 ppm or less) was added to a 1.5 l stainless steel autoclave.
00 g, 104.0% tetra-n-propylammonium hydroxide aqueous solution 224.0 g, and ethanol 214 g were charged, and 3
Stir vigorously for 0 minutes. The pH of the mixed solution was 13. After closing the lid of the autoclave, it was immersed in an oil bath to keep 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 inside the autoclave reached 2-3 kg / cm ² . The pH at the end of hydrothermal synthesis was 11.8. The white solid product was filtered off and then washed successively with distilled water until the pH of the washings was around 7. After drying the white solid, 530 under air circulation.
The mixture was baked at 4 ° C. for 4 hours to obtain 27 g of powdery white crystals. As a result of powder X-ray diffraction analysis of the crystal, it was identified as a pentasil-type zeolite. As a result of elemental analysis by an atomic absorption method, the content of Al was 3 ppm. This crystal 10
100 g of 5% ammonium chloride aqueous solution was added to g
After performing an ion exchange treatment at -60 ° C for 1 hour, the crystals were filtered off. After performing this ion exchange treatment four times, the crystals were washed with distilled water until Cl ⁻ ions were not detected in the washing liquid. Subsequently, the crystals are dried at 120 ° C. for 16 hours, and the obtained ammonium salt type crystals are pressure-molded and then 2
Sieve to 4-48 mesh. Further, the crystals were calcined under a nitrogen gas flow at 500 ° C. for 1 hour to obtain a catalyst.

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

The space velocity WHSV of cyclohexanone oxime was calculated by the following equation, and the conversion rate 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 (%) = [(X−Y) / X] × 100 ε-caprolactam selectivity (%) = [Z / (X−Y)] × 100 Further, O, C, X, Y and Z are as follows. O = Cyclohexanone oxime feed rate (kg / hr) C = Catalyst weight (kg) X = Number of moles of the starting material cyclohexanone oxime Y = Number of moles of unreacted cyclohexanone oxime Z = Number of moles of ε-caprolactam in the product

[0023]

[Table 1]

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

[0025]

[Table 2]

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

[0027]

[Table 3]

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

[0029]

[Table 4]

Comparative Example 1 The cyclohexanone oxime / methanol weight ratio is 1 /
A mixed solution of 1.8 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 reaction tube was supplied in ^-1 ). The reaction results are shown in Table 5. The amount of water in cyclohexanone oxime used as a reaction raw material was analyzed and found to be 0.3% by weight, which was equivalent to 0.019 mol per 1 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 converted into 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. Boric acid was eluted immediately after the start of the reaction, and the reaction was substantially impossible.

Claims (1)

[Claims] 1. A zeolite catalyst is used in the presence of an alcohol and / or ether compound, and water is allowed to coexist in the reaction system in the range of 0.06 to 2.5 mol per 1 mol of cyclohexanone oxime in the gas phase. A process for producing ε-caprolactam, which comprises reacting an oxime in a catalytic manner.