JPS58120507A - Continuous manufacture of hydrazine - Google Patents

Abstract

PURPOSE:To manufacture hydrazine industrially advantageously in a method for synthesizing azine from ketone, NH3 and H2O2, by using methanol as a solvent and by recovering methyl ethyl ketone as a by-product together with a reaction product contg. methanol. CONSTITUTION:In an azine synthesizing stage A, a liq. starting material consisting of methyl ethyl ketone (MEK), NH3, H2O2 and CH3OH is continuously fed 1 to a fixed bed packed with silica gel catalyst, and the material is reacted under heating. The liq. reaction product 2 is fed to a separating and recovering stage B, where unreacted NH3 is recovered, H2O2 is decomposed, and CH3OH is separated by distillation. At this time, a liq. mixture 5 of MEK with water separated in the latter hydrolyzing stage C besides the liq. reaction product 2 is fed to a distilling column for recovering a solvent in the stage B. An azeotropic mixture of MEK with CH3OH is obtd. from the top of the column, circulated 6, and used as it is as part of a starting material and part of a solvent in the stage A.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method for synthesizing methyl ethyl ketone azine by contacting methyl ethyl ketone, ammonia and hydrogen peroxide with a solid catalyst, and then hydrolyzing the same to produce hydrazine.

A method is known in which a ketone, ammonia and hydrogen peroxide are reacted in the presence of a catalyst to form the corresponding =4 zine, which is then hydrolyzed.

2 RCOR'+ 2 NH3+ H,,02RR → ) C= N-N=C<R, + 4 H20R' RR R,) C=N-N=C<R, +2Hρ →NH2NH2+ 2 RCOR' (However, R and R' each represent an alkyl group or an aryl group.) As shown in the above reaction formula, in this method, in the subsequent hydrolysis step of ketazine, hydrazine is produced and twice the mole of ketazine is generated. Ketonga is a by-product. Therefore, if this by-product ketone can be recovered and reused as a starting material,
Theoretically, the process of producing i-drazine using ammonia and hydrogen peroxide as raw materials is possible, and furthermore, as the type of ketone that should be recycled and reused between the above two reactions, it is the cheapest of the ketones, Moreover, if acetone is used, which has a low boiling point and therefore requires low cost for separation and recovery by distillation, it is expected that the process will be economically very advantageous.

However, in reality, the reaction of synthesizing azine from this ketone, ammonia, and hydrogen peroxide is a relatively distant reaction, and in order to obtain the target azine in good yield, including suppressing by-products, various steps must be taken to obtain the desired azine in good yield. Improvements and innovations must be made. In addition, in order to make the process economically advantageous for industrial implementation, it is not enough to simply improve the reaction performance;
Utilization of unreacted and by-product useful substances, separation of these, reduction of recovery costs, ease of operation, etc. must also be considered as important factors.

As a method for synthesizing azine from ketone, ammonia, and hydrogen peroxide, for example, 2) a method using IJ or amide as a co-reactant (JP-A No. 47-1371, No. 47-14098,
49-18815, etc.) and methods using selenium or tellurium compounds as catalysts (Japanese Patent Application Laid-open No. 50-50310). However, in these methods, the co-reactant and catalyst are dissolved in the reaction solution. Since the reaction takes place, separation from the reaction solution is troublesome, and especially in the former method, the nitrile and amide as co-reactants change into amide and carboxylic acid ammonium salt, respectively, so it is difficult to regenerate them. It is difficult to say that it is an economically advantageous method, including the cost of combining complicated steps such as separation from reaction products, recovery, and regeneration.

In addition, selenium and tellurium as catalysts in the latter method are highly toxic substances, and for safety reasons, thorough measures must be taken to handle them and treat wastewater from the manufacturing process, etc. in industrial manufacturing methods. This is not necessarily an appropriate method. On the other hand, if a solid catalyst such as silica gel disclosed in JP-A-54-135718 is used, separation from the reaction solution is easy regardless of whether it is a moving bed or a fixed bed, and the above-mentioned problems can be avoided. By the way, in this reaction, the type of raw material ketone has a relatively large effect on the yield of the azine obtained, and the combination with the solvent can reduce the amount of unreacted components and hydrolysis in the azine synthesis process. It is recognized that the separation and recovery process of by-products and its efficiency differ greatly. For example, acetone may seem advantageous at first glance from the point of view of price and boiling point, but from the point of view of reactivity (azine yield), methyl ethyl ketone provides a higher yield, and when separated by distillation, However, it was recognized that it had a number of advantages as described below. On the other hand, regarding the solvent, if it is not used, the starting material ketone will essentially play the role of a solvent, but in this case, there will be a noticeable increase in side reactions due to condensation of the starting material ketone, and it will also There are also problems in adjusting the supply ratio.

In addition, for the above reasons, when methyl ethyl ketone is used as a raw material ketone and no solvent is used, when recovering it as an unreacted component in the azine synthesis step, methyl ethyl ketone and water will distill out as an azeotrope in normal distillation. If this product is recycled as it is to the azine synthesis step, various problems will occur, such as accumulation of water in the reaction system and a decrease in the azine yield. However, when methanol is used as a solvent, the production of by-products is reduced and the yield of azine is improved, and the catalyst activity and selectivity to the target product are only slightly reduced due to long-term operation. Furthermore, in terms of separation and recovery, in combination with methyl ethyl ketone, when the solvent and unreacted raw materials are distilled off from the product after the completion of the reaction, methanol and methyl ethyl ketone form an azeotrope and release water. It was recognized that it has the advantage of being able to be recovered without containing it. That is, when distilling and separating the solvent, unreacted raw materials, desired products, and by-products (organic substances and water) in the reaction solution in the azine synthesis process, an azeotrope is formed in the combination of methanol and methyl ethyl ketone. The boiling point is approximately 10°C lower at normal pressure than the azeotropic system of methyl ethyl ketone and water, and there is no other azeotropic system with a similar boiling point, so it is easy to separate from the reaction liquid without containing water. becomes.

This separated and recovered methanol/methyl ethyl ketone mixture can be recycled as it is to the reaction process as a solvent and a reaction raw material, but in a more advantageous process, it is separated from the subsequent hydrolysis reaction process. By treating the azeotrope of methyl ethyl ketone and water together, it is possible to dehydrate methyl ethyl ketone from the process, making it a very economical process in practice.

As explained above, the present inventors have succeeded in selecting the most effective reaction starting materials, catalysts, and solvents and skillfully combining them to create a continuous process, and have completed the method of the present invention. It is something that

That is, the present invention synthesizes methyl ethyl ketone azine by continuously contacting and reacting methyl ethyl ketone, ammonia, and hydrogen peroxide with a solid catalyst in the coexistence of a methanol solvent.
In this method, hydrazine is obtained by hydrolyzing the hydrazine, and unreacted and by-product methyl ethyl ketone is recovered and reused. It is an object of the present invention to provide a method characterized in that it is sent to a solvent recovery step together with a reaction mixture containing a methanol solvent, separated by distillation as an azeotrope with methanol, and recycled to the azine synthesis step.

Hereinafter, the method of the present invention will be explained in more detail with reference to the accompanying drawings.

The attached drawing is a block diagram conceptually showing the method of the present invention, where 0 indicates the azine synthesis step, 0 indicates the separation and recovery step of unreacted raw materials, solvents, products, etc., and 0 indicates the hydrolysis step. Numbers (1) to (6) indicate the flow of substances.

In the Amisaki gin synthesis process, silica gel catalyst (Unexamined Japanese Patent Publication No. 5
A raw material liquid consisting of methyl ethyl ketone, ammonia, hydrogen peroxide, and methanol is continuously supplied to a fixed bed or a moving bed of a solid catalyst such as 4-135718) (1) and reacted under heating. Similarly, hydrogen peroxide is usually used as an aqueous solution, and polycarboxylic acids of alkylene polyamines or their salts or phosphoric acid compounds may be added as stabilizers, so the raw material solution contains a small amount of water in addition to the above. and stabilizers.

There are no strict restrictions on reaction conditions such as the composition of the raw material liquid supplied to the reactor, supply rate, reaction temperature and pressure, but in order to carry out the reaction efficiently, it is usually carried out within the following ranges. It is preferable. Regarding the composition of the raw material liquid, the hydrogen peroxide concentration in the raw material liquid is 05 to 3 mol/l, and the ketone and ammonia are each 1 to 1 mol/l per 1 mol of hydrogen peroxide.
0 mol, more preferably 2 to 5 mol, and the raw material liquid of this composition is used as catalyst 11/hr to 5 l/hr.
It is preferable to feed at a rate of . In addition, the reaction temperature is 40~
120°C, more preferably 50-90°C, reaction pressure:
Normal pressure to 50 da/cr/I.

The reaction solution (2) from the azine synthesis step is subjected to treatments such as recovery of unreacted ammonia and decomposition of hydrogen peroxide in a separation and recovery step, and further the methanol solvent is separated by distillation. In this case, the reaction liquid (2) is used as the feed liquid to the distillation column for solvent recovery.
In addition, a mixed solution (5) of methyl ethyl ketone and water separated in the subsequent hydrolysis step is also treated. Methanol and an azeotropic mixture of methanol and methyl ethyl ketone are obtained from the top of the solvent recovery column, and this is recycled (6) and used as it is as part of the solvent and raw material for the azine synthesis step.

Methyl ethyl ketone azine, methyl ethyl ketoxime, etc. as by-products, and water are distilled out from the bottom of the solvent recovery tower, so the by-products are separated and removed, and the composition is adjusted as necessary to use as a raw material for hydrolysis (3) Feed to the hydrolysis process. Hydrolysis of methyl ethyl ketone and zine is relatively easy, and even without a catalyst, hydrazine and methyl ethyl ketone are produced almost quantitatively by heating with water.

Of course, it is possible to use a catalyst if necessary, and there are no particular restrictions on the type of reactor. raw material supply rate,
The reaction conditions in the hydrolysis process, such as reaction temperature and pressure, cannot be specified because they vary depending on the reaction type and whether or not a catalyst is used. For example, in general, 1 mole of methyl ethyl ketone azine is used, 3 to 30 moles of water, the bottom temperature of the column is 150 to 230°C, and the pressure inside the column is 2 to 25 kg/-.
It is appropriate to do this within the following range.

Methyl ethyl ketone produced in the hydrolysis step is separated as an azeotrope together with water present in the system. Since this contains a relatively large amount of water, it cannot be directly recycled to the azine synthesis process, but as mentioned above, it can be distilled together with the reaction liquid (2) from the azine synthesis process (5) in a solvent recovery column. can be substantially separated from water. The product liquid (4) of the hydrolysis step is purified by a conventional method to obtain hydrazine.

According to the method of the present invention, the solvent, raw material, and catalyst are industrially easily available and inexpensive compounds, and the yield of Yajijin obtained is also high. In addition, in the gin synthesis reaction, it is only necessary to pass the reaction raw material liquid through the layer where the catalyst is present, so it is easy to separate the reaction product liquid from the catalyst. There are no disadvantages that require significant costs. Furthermore, according to the method of the present invention, excess methyl air ethyl ketone used in the gin synthesis reaction and methyl ethyl ketone recovered from the gin hydrolysis step can be dehydrated without a separate dehydration step. Since it can be recovered in , the Gojin synthesis reaction can be carried out advantageously, and the amount of energy T used can also be reduced.

As is clear from the many advantages of the method of the present invention as described above, the present invention aims to provide an industrially advantageous method for producing hydrazine.

Hereinafter, typical examples of the method of the present invention will be shown and explained in more detail, but these are merely examples shown to facilitate understanding of the method of the present invention, and this is the only method of the present invention. Needless to say, the invention is not limited to this, and is not limited to this in any way.

Example azination reaction was carried out using an inner diameter 16 mm filled with granular silica gel.
(2) Two 3 m long stainless steel reaction tubes (with jackets) are connected in series. The rate of reaction raw material liquid is 231.0% per hour.
It is fed at a rate of 84.9. This is 6.28g of ammonia recycled from the ammonia recovery tower and solvent recovery tower.
Methyl ethyl ketone
, methanol 155.21 water 0.42. .

9 and 10.94 g of 65% hydrogen peroxide aqueous solution (
BDTA・2Na 2■ and sodium dihydrogen phosphate 1■
) and 6.18 g of ammonia were mixed. The pressure of the azination reaction is 6. It was OK5/d, and the jacket temperature was kept at 70°C. The catalytic activity of the azination reaction decreases by 2 to 3% at the initial stage of the reaction, but thereafter stabilizes and becomes approximately constant.

After 300 hours of continuous azination reaction, the production rate of methyl ethyl ketone azine was 23.55 g, which was 80.3% based on the supplied hydrogen peroxide.
This corresponds to a yield of In addition to this, 0.82 El/hrGF
Methyl ethyl ketoxime (equivalent to 4.5% based on ik hydrogen oxide) was produced. After the residual hydrogen peroxide in this reaction liquid is decomposed, it is supplied to an ammonia recovery tower to recover ammonia. 3. From the top of the ammonia recovery tower.
04p/hr of ammonia was recovered, while methyl ethyl ketone 7.599/hr and methanol 17.71/hr were recovered.
jJ/hr will also be accompanied. The water content in this tower top liquid was 0.2Wt 1 or less. The distillate from the top of the column is returned to the azination step. A of the ammonia recovery tower.

The solution discharged from the bottom of the column is combined with the top liquid of the Soshin hydrolysis column and supplementary methyl ethyl ketone, etc. and supplied to the solvent recovery column. A liquid is supplied to the solvent recovery column at a rate of 199.019A1r, and this liquid contains methyl ethyl (methyl ethyl)y 37.60
．． 9/Ilr methanol 119.82 fi/hr, water 25.70 g/hr, ammonia 0.19. ! 7/h
In addition to r, methyl ethyl ketone azine, methyl ethyl ketone oxime, etc. are contained. In the solvent recovery column, the pressure is slightly reduced so that the temperature at the bottom of the column is maintained at 80° C., and methyl ethyl ketone, methanol, and ammonia are recovered from the top of the column and recycled to the azination process together with the top liquid of the ammonia recovery column. The amount of water mixed in this recovered liquid is Q,2
It was less than wt%. The bottom liquid of the solvent recovery tower contains water,
After removing methyl ethyl ketone oxime and other by-products, it is fed to a hydrolysis tower. The hydrolysis tower consists of a recovery section, an intermediate section, and a concentration section.

The hydrolysis reaction and the simultaneous recovery of methyl ethyl ketone are carried out at a pressure in the column of 8 to shoulder, a temperature at the top of the column of 140℃, and a temperature at the bottom of the column at 180℃.
It was operated at ℃. The feed rate of methyl ethyl ketone azine to the hydrolysis tower is 23.60 g/hr, and the feed rate of water is 21.189/hr, so that azine and azine are also fed to the top. An azeotropic composition of methyl ethyl ketone and water (containing 0.15 wt % azine) is recovered from the top of the column and recycled to the solvent recovery column.

A 47.5% aqueous hydrazine Hitlerde solution was recovered from the bottom of the column.

[Brief explanation of the drawing]

Patent applicant: Showa Denko Co., Ltd. Agent Sei Kikuchi

Claims (1)

[Claims] Methyl ethyl ketone azine is synthesized by continuously contacting methyl ethyl ketone, ammonia, and hydrogen peroxide with a solid catalyst in the coexistence of a methanol solvent, and this is hydrolyzed to obtain hydrazine, and unreacted and by-product methyl ethyl ketone is recovered. In the method of circular reuse,
The by-product methyl ethyl ketone in the hydrolysis step is sent to the solvent recovery step together with the reaction mixture containing unreacted methyl ethyl ketone and methanol solvent in the azine synthesis step 9, and is separated by distillation as an azeotrope with methanol. A method characterized by recycling the azine to the azine synthesis step.