JP2003238511A - Method for producing nitrile compound - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a method for producing a nitrile compound from a carbocyclic compound or a heterocyclic compound having an organic substituent, ammonia and air by a vapor-phase catalytic ammoxidation reaction, realizing a reaction under a good condition by adjusting a supplied gas composition and the contact time, or the like, without using a particular auxiliary apparatus and producing the nitrile compound on an industrial scale in high yield at a low cost. <P>SOLUTION: The residual gas component left after the separation of the nitrile compound from the ammoxidation reaction gas is returned to a reactor at a specific ratio while keeping the molar ratio of the molecular oxygen to the organic substituent of the carbocyclic compound or heterocyclic compound supplied to the reactor within a specific range. <P>COPYRIGHT: (C)2003,JPO

Description

Detailed Description of the Invention

[0001]

TECHNICAL FIELD The present invention relates to a method for producing a carbocyclic nitrile compound or a heterocyclic nitrile compound by an ammoxidation reaction using a carbocyclic compound or a heterocyclic compound having an organic substituent as a raw material.

[0002]

BACKGROUND OF THE INVENTION Carbocyclic nitrile compounds are useful as raw materials for producing synthetic resins, agricultural chemicals and the like, and as intermediate raw materials for amines, isocyanates and the like. On the other hand, the heterocyclic nitrile compound is useful as an intermediate raw material for medicines, feed additives, food additives and the like. A method of reacting an organic compound such as a carbocyclic compound or a heterocyclic compound having an organic substituent (hereinafter referred to as an organic substituent compound) with ammonia and an oxygen-containing gas is called ammoxidation, and is generally performed by a gas phase catalytic reaction to produce a nitrile. The compound is produced. A catalyst containing vanadium, molybdenum, iron and the like is known for the ammoxidation.
For example, a method of ammoxidating an alkyl-substituted aromatic hydrocarbon compound or heterocyclic compound using a catalyst containing a V-Cr-B-Mo oxide has been proposed (see Patent Document 1). Further, a method of producing dicyanobenzene by ammoxidation of xylene using a catalyst containing an Fe-Sb-V-based oxide has been proposed (Patent Document 2).
reference. ).

[0003]

[Patent Document 1] Japanese Patent Laid-Open No. 11-209332

[Patent Document 2] Japanese Patent Laid-Open No. 9-71561

[0004]

The reaction conditions such as feed gas composition, contact time, reaction temperature, etc. in the ammoxidation reaction are as follows:
It is an important factor that determines the yield and productivity of nitrile compounds and must be strictly controlled. On the other hand, when producing a nitrile compound by ammoxidation, air is industrially used as an oxygen source. When air is used as the oxygen source, the oxygen content in the air is constant, so that it is often the case that the optimum feed gas composition and contact time cannot be selected. Pure oxygen, nitrogen, etc. can be used to adjust the supply gas composition, but when using pure oxygen or nitrogen, a separate production facility for these gases is required, which increases construction costs and is not industrially preferable. .

An object of the present invention is to provide a method for producing a nitrile compound by a gas phase catalytic ammoxidation reaction using a carbon ring compound or a heterocyclic compound having an organic substituent, ammonia and air as raw materials, and supplying the nitrile compound without special auxiliary equipment. It is an object of the present invention to provide a method for obtaining a nitrile compound industrially advantageously with a high yield by realizing a reaction under favorable reaction conditions by adjusting the gas composition, contact time and the like.

[0006]

Means for Solving the Problems As a result of intensive investigations by the present inventors, the residual gas component after separating the nitrile compound from the ammoxidation reaction gas was re-supplied to the reactor in a specific amount, and the reaction was performed at that time. Found that the above object can be achieved by setting the molar ratio of molecular oxygen to the organic substituent of the carbocyclic compound or the heterocyclic compound supplied to the vessel within a specific range,
The present invention has been reached.

That is, the present invention is a method for producing a nitrile compound by introducing a carbocyclic compound or a heterocyclic compound having an organic substituent, ammonia and air into a reactor and reacting them in the presence of a catalyst. The residual gas after separating the nitrile compound generated from the reaction gas discharged from the reactor is a new raw material gas consisting of a carbon ring compound or heterocyclic compound having an organic substituent newly supplied to the reactor, ammonia, and air. With respect to the organic substituent of the carbocyclic compound or the heterocyclic compound supplied to the reactor again by 10 to 60% by volume relative to the molar ratio of molecular oxygen (O ₂ / organic substituent ) Is carried out in the range of 1.5 to 7, which is a method for producing a nitrile compound.

DETAILED DESCRIPTION OF THE INVENTION

The carbocyclic compound having an organic substituent as a raw material used in the present invention has a carbocyclic ring such as benzene, naphthalene, anthracene, cyclohexene, cyclohexane, dihydronaphthalene, tetralin and decalin, and a methyl group in its side chain. , Ethyl group, propyl group, formyl group,
It is a carbocyclic compound having an organic substituent such as an acetyl group, a hydroxymethyl group and a methoxycarbonyl group. Also,
The carbocyclic compound may further contain a substituent such as a halogen group, a hydroxyl group, an alkoxy group, a phenyl group, an amino group and a nitro group which does not participate in the ammoxidation reaction. Specific examples include toluene, xylene, trimethylbenzene, ethylbenzene, methylnaphthalene, dimethylnaphthalene, methyltetralin, dimethyltetralin, chlorotoluene, dichlorotoluene, methylaniline, cresol, methylanisole and the like. Further, the heterocyclic compound having an organic substituent as a raw material is furan, pyrrole, indole, thiophene, pyrazole,
Heterocyclic compounds having the above-mentioned organic substituent in the heterocycle such as imidazole, oxazole, pyran, pyridine, quinoline, isoquinoline, pyrroline, pyrrolidine, imidazoline, imidazolidine, piperidine, piperazine.
The side chain thereof may contain a substituent that does not participate in the ammoxidation reaction as in the above carbocyclic compound. Specific examples include furfural, 2-methylthiophene, 3-methylthiophene, 2-formylthiophene, 4-methylthiazole, methylpyridine, dimethylpyridine, trimethylpyridine, methylquinoline, methylpyrazine, dimethylpyrazine, methylpiperazine and the like. Can be mentioned. These compounds can be used alone or in a mixture. Of these, the present invention is particularly preferably applied to the method for producing isophthalonitrile from metaxylene having two methyl groups on the benzene ring.

In the present invention, a nitrile compound is produced by a vapor-phase catalytic ammoxidation reaction. Examples of the reaction format of the ammoxidation reaction include fixed bed, moving bed, fluidized bed and the like, but the fluidized bed format is preferably used from the viewpoint of reaction temperature control, equipment cost and the like. The catalyst used in the present invention is not particularly limited as long as it is an ammoxidation catalyst suitable for a gas phase catalytic reaction. For example, a catalyst containing an oxide of at least one element selected from vanadium, molybdenum and iron is preferably used. In the case of a fluidized bed catalyst, the particle size of the catalyst is 10 to 3
The range is 00 μm, and the average particle size is 30 to 200 μm, preferably 40 to 100 μm. The bulk density of the catalyst is 0.5 to 2 g / cm ³ , preferably 0.7 to 1.5 g / cm ³ .
It is in the range of cm ³ .

As the raw material ammonia, industrial grade ones can be used. The amount of ammonia used is in the range of 1 to 10 moles, preferably 3 to 7 moles, as the molar ratio of ammonia (NH ₃ / organic substituent) to the organic substituents contained in the raw material carbocyclic compound or heterocyclic compound. Is. If the amount used is less than the above range, the yield of the nitrile compound decreases, while if it exceeds the above range, it is industrially disadvantageous due to loss of unreacted ammonia or increase in recovery cost. In the present invention, the residual gas component after separating the target nitrile compound from the reaction gas discharged from the reactor outlet is re-supplied to the ammoxidation reactor, but ammonia cannot be ignored in this residual gas. When it is contained in an amount, the amount of ammonia newly supplied may be adjusted appropriately.

Air is used as the oxygen source of the present invention. The amount of air used is 1.5 to 7 times mol, preferably 1.5 to 7 times, as a molar ratio of oxygen (O ₂ / organic substituent) to the organic substituent contained in the raw material carbon ring compound or heterocyclic compound.
Adjust so that the molar ratio is in the range of 5 times. If the amount used is less than this, the yield of the nitrile compound will decrease, while if it is more than this, the space-time yield will decrease. In the present invention, from the reaction gas discharged from the reactor outlet, re supplying residual gas component after separating the nitrile compound as the target compound in ammoxidation reactor, the O ₂ / organic substituent ratio Since it is necessary to control, if the residual gas contains a non-negligible amount of oxygen, the amount of newly supplied air may be adjusted appropriately.

The reaction pressure for ammoxidation may be atmospheric pressure, elevated pressure or reduced pressure, but is preferably in the range of approximately atmospheric pressure to 0.2 MPa. The contact time between the reaction gas and the catalyst depends on the kind of the organic substituent compound, the composition of the feed material, the reaction temperature, etc., but is usually in the range of 0.5 to 30 seconds.

The reaction temperature is in the range of 300 to 500 ° C, preferably 330 to 470 ° C. If the reaction temperature is lower than this, a sufficient reaction rate cannot be obtained. On the other hand, if the reaction temperature is higher than this, by-products such as carbon dioxide and hydrogen cyanide increase,
The yield of nitrile compound decreases. The reaction temperature is appropriately selected to a temperature at which the optimum yield can be obtained under the above operating conditions, taking into consideration the activity of the catalyst.

In the present invention, the residual gas component after separating the target nitrile compound from the reaction gas discharged from the reactor outlet is re-supplied to the ammoxidation reactor. As a method for separating and recovering the nitrile compound from the reaction gas, (1) contacting the reaction gas with an organic solvent in which the nitrile compound is soluble to collect the nitrile compound in the solvent,
A method of separating residual gas components. (2) A method in which the reaction gas is cooled to precipitate or condense the nitrile compound as a solid or liquid to separate it from the residual gas component, and the like .
In the case of the method (1), an organic solvent such as an alkylbenzene, a heterocyclic compound, an aromatic nitrile, or a heterocyclic nitrile is used as the organic solvent, but when the nitrile compound produced in the ammoxidation reaction is used, the handling substance increases. It is advantageous without doing. For example, when isophthalonitrile is obtained from metaxylene, metatolunitrile produced as a by-product in the ammoxidation reaction can be preferably used.

The residual gas after separation of the nitrile compound contains nitrogen as a main component, and additionally contains oxygen, ammonia, carbon dioxide, carbon monoxide, hydrogen cyanide, water, unreacted organic substituent compound and the like. This residual gas may be supplied to the ammoxidation reactor as it is, but if necessary, it is mainly nitrogen after separating components such as water, carbon dioxide, hydrogen cyanide, ammonia, and unreacted organic substituent compounds. The residual gas as a component may be supplied to the ammoxidation reactor again. As such a method, for example, in Japanese Unexamined Patent Publication No. 2001-348370, we previously absorbed unreacted ammonia and hydrogen cyanide from the residual gas after separating the nitrile compound into water, separate and collect it, and return it to the reaction system. Although a method is proposed, this method produces a residual gas in which ammonia and hydrogen cyanide are separated in addition to the nitrile compound from the reaction gas discharged from the reactor outlet, and thus this residual gas is fed to the ammoxidation reactor. You may use for resupply.

In the present invention, the amount of residual gas re-supplied to the ammoxidation reactor is 10 to 60% by volume based on the amount of new raw material gas consisting of the organic substituent compound, ammonia and air newly supplied to the reactor. Yes, preferably 15 to 50% by volume. If the re-supply amount is less than this, the effect of the present invention cannot be sufficiently obtained, and if the re-supply amount is more than this, the circulation amount increases and the space-time yield decreases. The volume% in the present invention means a volume ratio in a so-called standard state of 0 ° C. and 1 atm. In the present invention, when the residual gas is re-supplied to the ammoxidation reactor, the molar ratio of molecular oxygen to the number of organic substituents (O ₂ / organic substituent ratio) of the organic substituent compound supplied to the reactor is 1. 5-7, preferably 1.
The reaction is carried out in the range of 5-5. Therefore, in the present invention, the re-supply residual gas amount (re-supply residual gas amount / new raw material gas amount) with respect to the new raw material gas amount is within the range of 10 to 60% by volume,
Further, the resupply residual gas amount and the air supply amount are adjusted so that the O ₂ / organic substituent ratio is in the range of 1.5 to 7. When adjusting the supply amount, the oxygen concentration of the resupply residual gas can be measured to determine an appropriate supply amount. The oxygen concentration of the resupply residual gas can be easily measured by a gas chromatograph or a commercially available oxygen concentration sensor. Like this
_By controlling the ratio of ₂ / organic substituents to an appropriate range and resupplying an appropriate amount of residual gas containing nitrogen as a main component to the reactor,
The effect of improving the yield is obtained in the ammoxidation reaction.

The concentration of the organic substituent compound in the gas supplied to the reactor in the present invention is in the range of 0.2 to 10% by volume, preferably 0.5 to 5% by volume. If it is higher than this concentration, the yield of the nitrile compound is lowered, while if it is lower than this concentration, the space-time yield is lowered. In the practice of the present invention, the concentration of the organic substituent compound is set to 0.07 mol or less based on 1 mol of all the components supplied to the reactor as the number of mols of the organic substituent, and a good yield is obtained. Thus, the present invention becomes more effective. The number of moles of the organic substituent with respect to 1 mole of all components supplied to the reactor is a value obtained by multiplying the volume concentration of the organic substituent compound by the number of the organic substituents of the organic substituent compound. For example, 1.5% by volume of xylene (having two methyl groups as organic substituents) is the total feed component 1 fed to the reactor.
The organic substituent concentration is 0.015 × 2 = 0.03 mol per mol.

FIG. 1 is a flow chart showing an example of an embodiment of the present invention. The ammoxidation reaction is carried out by a fluidized bed reaction, and the reaction gas discharged from the reactor is brought into contact with a solvent to collect the gas. This is a mode in which the residual gas after collection is brought into further contact with water to collect ammonia, and the residual gas is re-supplied to the ammoxidation reactor. In FIG. 1, 1 is an ammoxidation reactor, 2 is a nitrile collection tower, and 3 is a water washing tower. In FIG. 1, the ammoxidation reactor 1 is filled with a fluidized bed catalyst. An organic substituent compound, ammonia, air, and a resupply residual gas are supplied to the reactor to carry out an ammoxidation reaction. A cooling pipe is installed inside the reactor, and a fluidized catalyst bed interface is present below the upper end of the cooling pipe. The reaction gas is discharged from the discharge pipe after the catalyst particles are separated by the catalyst cyclone and returned to the fluidized catalyst bed from the return pipe. The reaction gas discharged from the reactor contains a nitrile compound, ammonia, hydrogen cyanide, carbon dioxide, water, carbon monoxide, nitrogen, oxygen, an unreacted organic substituent compound, and the like. Sent to 2. In the nitrile collection tower 2, the reaction gas and the solvent are brought into contact with each other to collect the nitrile compound contained in the reaction gas. The residual gas after collecting the nitrile is sent to the water washing tower 3 in the next step. In the flush tower, contact the residual gas and water,
Ammonia and hydrogen cyanide contained in the reaction gas are collected. Part of the residual gas obtained from the water washing tower 3 is re-supplied to the ammoxidation reactor, and the rest is guided to an exhaust gas treatment facility such as an incinerator.

[0019]

EXAMPLES Next, the present invention will be described more specifically by way of Examples and Comparative Examples. However, the present invention is not limited to these examples. The reaction results in the following examples are ratios with respect to the raw material meta-xylene.

<Catalyst preparation> Vanadium pentoxide V₂O_Five22
Add 500 ml of water to 9 g and heat to 80-90 ° C.
While stirring, 477 g of oxalic acid was added and dissolved. See you
400 ml of water was added to 963 g of oxalic acid, and the mixture was heated to 50-60 ° C.
Heat and add to this chromic anhydride CrO₃252g of water 200
The solution added to ml is added with sufficient stirring to dissolve.
The solution of vanadium oxalate thus obtained was added to oxalic acid.
A solution of chromium is mixed at 50-60 ° C., and vanadium-
Obtain a chromium solution. Phosphomolybdic acid H was added to this solution.
₃(PMo ₁₂O₄₀) ・ 20H₂O41.1g water 100m
dissolved in 1 and added, and potassium acetate CH₃COOK
Dissolve 4.0 g in 100 ml water and add. Then 20
Wt% aqueous silica sol (Na₂0.02 wt% O
Yes) Add 2500 g. Boric acid H was added to this slurry solution.
₃BO₃Add 78g and mix well until the liquid volume is about 3800g.
Heat until concentrated and concentrate. The catalyst solution is heated to an inlet temperature of 25
Spray drying was performed while maintaining 0 ° C and an outlet temperature of 130 ° C. Jet
The mist-dried catalyst was dried in a dryer at 130 ° C for 12 hours.
Bake at 400 ° C for 0.5 hours, then at 550 ° C for 8 hours
A fluidized catalyst was produced by firing under flowing air. Of catalyst component
The atomic ratio of V: Cr: B: Mo: P: Na: K is 1:
1: 0.5: 0.086: 0.007: 0.009:
0.020, and the concentration of the catalyst component in the fluidized catalyst is
It is 50% by weight.

Comparative Example 1 An ammoxidation reaction of metaxylene was carried out using the ammoxidation reactor shown in FIG. The ammoxidation reactor was filled with 2300 kg of the fluidized catalyst prepared above, and air, metaxylene (MX), and ammonia gas were preheated to a temperature of 180 ° C. and supplied to the reactor. Supply amount is MX supply amount 242kg /
h, ammonia supply amount 342 kg / h, air 1390 N
m ³ / h. The reaction was performed at a reaction pressure of 0.08 MPa to obtain isophthalonitrile (IPN). The reaction gas discharged from the reactor was introduced into a nitrile collection tower, and a methatrinitrile solvent was brought into contact therewith to collect the nitrile compound contained in the reaction gas. The residual gas after the nitrile was collected was introduced into the water washing tower 3 and brought into contact with water to collect ammonia and hydrogen cyanide contained in the reaction gas. All the residual gas discharged from the water washing tower was led to the exhaust gas treatment facility without being re-supplied to the ammoxidation reactor. When the reaction temperature was adjusted, the IPN yield became maximum at the reaction temperature of 431 ° C, and the reaction results were as follows: IPN yield 82.3 mol%, methanitrile yield 1.3%, combustion components (carbon dioxide, carbon monoxide). , Hydrogen cyanide) was 13.5%.

Example 1 Residual gas 830N discharged from the washing tower in Comparative Example 1
m ³ / h was re-supplied to the ammoxidation reactor, and the reaction amount was changed to 1200 Nm ³ / h of air and the reaction temperature was changed to 441 ° C. to carry out the reaction. The oxygen concentration of the residual gas obtained from the water washing tower 3 was 5.2% by volume. At this time, the amount of the residual gas to be re-supplied with respect to the new raw material gas was 48.8% by volume, the O ₂ / organic substituent ratio was 2.9, and the number of moles of the organic substituent was 1 mole of all the components supplied to the reactor. 0.0
It was 40. The reaction results are IPN yield 87.1 mol%,
The yield of methanitrile was 4.1% and the yield of combustion components (carbon dioxide, carbon monoxide, hydrogen cyanide) was 6.2%, and the IPN yield was higher than that of Comparative Example 1.

Example 2 Residual gas 650N discharged from the water washing tower in Comparative Example 1
m ³ / h was re-supplied to the ammoxidation reactor, and the reaction amount was changed to 1300 Nm ³ / h of air and the reaction temperature was changed to 438 ° C. to carry out the reaction. The oxygen concentration of the residual gas obtained from the water washing tower 3 was 5.6% by volume. At this time, the amount of the residual gas to be re-supplied to the new raw material gas was 36.1% by volume, the O ₂ / organic substituent ratio was 3.0, and the number of moles of the organic substituent was 1 mole of all the components supplied to the reactor. 0.0
It was 42. The reaction results are IPN yield 86.1 mol%,
The yield of methatrinitrile was 3.3%, and the yields of combustion components (carbon dioxide, carbon monoxide, hydrogen cyanide) were 8.4%, which was higher than that of Comparative Example 1.

Example 3 350 N of residual gas discharged from the water washing tower in Comparative Example 1
m ³ / h was re-supplied to the ammoxidation reactor, and the reaction condition was changed to 1320 Nm ³ / h of air and the reaction temperature was 433 ° C. to carry out the reaction. The oxygen concentration of the residual gas obtained from the water washing tower 3 was 4.6% by volume. At this time, the amount of residual gas to be re-supplied with respect to the new raw material gas was 19.2% by volume, the O ₂ / organic substituent ratio was 2.9, and the number of moles of the organic substituent was 1 mole of all the components supplied to the reactor. 0.0
It was 47. The reaction results are IPN yield 84.2 mol%,
The yield of methatornitrile was 1.9%, and the yield of combustion components (carbon dioxide, carbon monoxide, hydrogen cyanide) was 12.1%, which was higher than that of Comparative Example 1.

[0025]

Industrial Applicability According to the method of the present invention, a reaction under more preferable reaction conditions can be realized, and a nitrile compound can be industrially obtained with a high yield.

[Brief description of drawings]

FIG. 1 is a flow chart showing an example of an embodiment of the present invention, in which an ammoxidation reaction is carried out in a fluidized bed reaction, and a reaction gas discharged from a reactor is brought into contact with a solvent to collect the reaction gas.
This is a mode in which the residual gas after the collection is further contacted with water to collect ammonia, and the residual gas is re-supplied to the ammoxidation reactor.

[Explanation of symbols]

1: Ammoxidation reactor 2: Nitrile collection tower 3: Wash tower

   ─────────────────────────────────────────────────── ─── Continued front page    (72) Inventor Fumio Tanaka             3500 Matsuhama-cho, Niigata City, Niigata Prefecture Mitsubishi Gas             Gaku Co., Ltd., Niigata Industrial Co., Ltd. (72) Inventor Takuji Shitara             3500 Matsuhama-cho, Niigata City, Niigata Prefecture Mitsubishi Gas             Gaku Co., Ltd., Niigata Industrial Co., Ltd. (72) Inventor Kazuhiko Amagawa             3500 Matsuhama-cho, Niigata City, Niigata Prefecture Mitsubishi Gas             Gaku Co., Ltd., Niigata Industrial Co., Ltd. F-term (reference) 4H006 AA02 AC54 AD18 BA02 BA12                       BA14 BA19 BA31 BA35 BA81                       BC10 BC30 BC31 BD20 BD33                       BD52 BD84 BE14 BE30 QN28                 4H039 CA70 CL50

Claims (6)

[Claims] 1. A method for producing a nitrile compound by introducing a carbocyclic or heterocyclic compound having an organic substituent, ammonia and air into a reactor and reacting them in the presence of a catalyst, which is discharged from the reactor. The residual gas component after separating the nitrile compound generated from the reaction gas is supplied to a new raw material gas consisting of a carbon ring compound or a heterocyclic compound having an organic substituent, ammonia and air, which is newly supplied to the reactor. 10 to 60% by volume and re-supplied to the reactor, and the molar ratio of molecular oxygen to the organic substituent of the carbocyclic compound or the heterocyclic compound (O) supplied to the reactor (O
₂ / organic substituent) is carried out in the range of 1.5 to 7. 2. The number of moles of organic substituents of the carbocyclic compound or heterocyclic compound supplied to the reactor is 0.07 mol or less based on 1 mol of all the components supplied to the reactor. The method of claim 1. 3. The method according to claim 1, wherein the reaction gas discharged from the reactor is brought into contact with a solvent to collect the nitrile compound. 4. The method according to claim 1, wherein the ammoxidation reaction is carried out in a fluidized bed. 5. The method according to claim 1, wherein the carbocyclic compound is metaxylene and the nitrile compound is isophthalonitrile. 6. The method according to claim 1, wherein a catalyst containing an oxide of at least one metal selected from vanadium, molybdenum and iron is used.