JPS5810384B2 - Production method of hexamethyleneimine - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION CI) Background of the Invention The present invention relates to the production of hexamethyleneimine by catalytic hydrogenation of ε-caprolactam.

Hexamethyleneimine is a compound useful as an intermediate raw material for biologically active substances, especially agricultural chemicals.

Until now, the method for producing this compound has been to convert ε-caprolactam into metal hydrides (e.g., LiAlH4, NaBH4).
etc.) [e.g. He l, Chi m
.

Acta, 32.544(49), Tetrahe
droneLetters, 1968(1)61,)
Alternatively, a method of removing ammonia from hexamethylene diamine has been proposed (for example, Ber, 96.924 (1963), Nikkashi 82° 1700 (1961), etc.).

However, the methods proposed so far seem to have problems such as low yields and expensive raw materials, and it is difficult to say that they are industrially useful methods.

In addition, as a catalyst for producing amines by catalytic hydrogenation reaction of amide, copper-chromium catalysts [e.g.
s, J, A, C, S, 56.2419 (1934)) and rhenium catalysts [e.g. H, Smith Broad
lent.

J, 0. C024, 1847 (1959)] is known to be good.

However, looking at the usage conditions of the above catalyst, the former has a reaction temperature of 200-300°C and a reaction pressure of 200-300°C.
A large amount of catalyst is used at 0 kg/criG and the amount of catalyst used is 10 to 20% or more.

The reason why a large amount of catalyst is used under such high pressure is that the water produced in the reaction decomposes the amide and generates acid, which poisons the catalyst, so it is necessary to terminate the reaction as quickly as possible. It is understood that it is from.

On the other hand, in the case of the latter rhenium catalyst, the amount of catalyst used is 1
~2% (based on the reactants), but the reaction temperature is ~150~
The reaction is carried out at a high pressure of 250° C. and a reaction pressure of 200 to 300 kg/crtiG.

In fact, when the present inventors applied the above-mentioned known catalyst to the catalytic hydrogenation reaction of ε-caprolactam, it was found that the activity was low as expected and it was difficult to use it for industrial practical use.This led to the development of a new catalyst or hydrogenation method. was informed that it was necessary.

On the other hand, it is well known that nickel or cobalt is effective as a hydrogenation catalyst.

However, when they were used in the catalytic hydrogenation of ε-caprolactam, their activity was low, and moreover, they were poisoned by the acid produced during the reaction, resulting in a significant decrease in activity.

When producing hexamethyleneimine industrially by catalytic hydrogenation of ε-caprolactam, the following three points are the main problems.

(a) Poisoning of the catalyst due to the cleavage of ε-caprolactam by water as a by-product to produce amino acids.

(b) Decrease in reaction rate due to cleavage polymerization of ε-caprolactam.

(c) Cleavage of hexamethyleneimine and other sequential reactions.

These findings are understood to have been first discovered by the present inventors, but (b) in particular should be considered unexpected as a cause of the decrease in the reaction rate of hexamethyleneimine.

When ε-caprolactam polymerizes, the rate at which hexamethyleneimine is produced is extremely reduced.

That is, in a coexisting system of ε-caprolactam polymer and hexamethyleneimine, the sequential reaction by catalytic hydrogenation of hexamethyleneimine takes precedence, and its speed is proportional to the concentration of hexamethyleneimine in g.

Furthermore, the polymerization reaction rate of ε-caprolactam is suppressed when the amount of coexisting water is small.

In order to solve these problems, an operation mode may be considered in which the target product hexamethyleneimine and the by-product water are extracted from the vapor phase by utilizing the boiling point difference.

However, it must be said that there are serious doubts as to whether or not such an operating mode will solve the above-mentioned problems.

That is, in this reaction, high-boiling-point byproducts accumulate significantly in the reaction liquid phase and the catalyst rapidly deteriorates, so there is a strong possibility that the hydrogenation reaction itself will be suppressed.

In fact, for example when using a Ni-diatomite catalyst (
In other cases, such as when the solvent is a lower alcohol, the reaction has to be stopped at an amount of time that is not practical.

SUMMARY OF THE INVENTION The purpose of the present invention is to provide a solution to the above-mentioned problems and efficiently carry out the catalytic hydrogenation of ε-caprolactam, and to achieve this purpose by adopting a specific hydrogenation mode. be.

Therefore, the method for producing hexamethyleneimine according to the present invention is a method for producing hexamethyleneimine by catalytic hydrogenation of ε-caprolactam, in which the raw material ε-caprolactam is added to the liquid phase of a catalytic reaction zone maintained at a substantially constant temperature. It is characterized in that it is supplied in a liquid phase and the reaction product is removed from the reaction zone in a vapor phase together with an excess of hydrogen gas.

As described above, the present invention solves the problems caused by the acidification of the reaction zone or the decomposition of the product due to the progress of catalytic hydrogenation of ε-caprolactam by adopting a specific hydrogenation mode. According to a specific mode of operation, the reaction temperature can be easily controlled and the decomposition of the produced hexamethyleneimine can be kept to a minimum.

That is, according to the vapor phase extraction according to the present invention, the following effects are achieved.

@) Since acidification of the reaction zone is suppressed, poisoning of the catalyst is suppressed.

(b) Water and hexamethyleneimine can be simultaneously and rapidly removed from the reaction zone without a catalyst separation step.

As a result, an improvement in yield is realized. (c) Low-boiling substances produced as a result of catalytic hydrogenation of high-boiling substances can also be removed.

That is, high-boiling substances undergo catalytic hydrogenolysis under vapor phase extraction conditions to become low-boiling substances such as lower hydrocarbons, ammonia, and lower amines, and are extracted from the reaction system.

b) Unreacted ε・-caprolactam can be recovered.

In other words, although the boiling point difference between ε-caprolactam and water or hexamethyleneimine is significantly different, the supplied ε
- A part of caprolactam is not hydrogenated and is extracted from the system together with water, hexamethyleneimine, lower amines, ammonia and other by-products, but it is advantageous to use a mixture of these by-products coexisting. Whether or not ε-caprolactam can be recovered is something that cannot be predicted based on a combination of known facts, and has been confirmed for the first time by the present invention.

(e) The reaction temperature can be easily controlled.

[■] Detailed Description of the Invention ■, Catalyst The process of this invention can be carried out using any catalyst capable of catalytic hydrogenation of ε-caprolamtam to produce hexamethylene.

Catalytic metal components include Ni, Co, Ni −
Co.

There are Ni-Re, Co-Re, Ni-Co-Re, and others.

Among these, Re-containing catalysts with good acid resistance are preferred in the present invention.

Among Re-containing catalysts, (1) Ni or (and)
Consisting of a close complex of Co and (2) Re (Japanese Patent Application No. 129583/1983 (Patent Application No. 86385/1989))
) is particularly preferred.

These catalysts, such as the particularly preferred Re-containing catalysts mentioned above, can be produced by various methods, including the presence or absence of a carrier and the manner in which the carrier is introduced. preferable.

The method uses a carrier containing a compound that decomposes into a metal containing nickel metal or cobalt metal or both by heating in a reducing atmosphere, and a rhenium compound that decomposes into metal rhenium by heating in a reducing atmosphere. and heating the resulting aggregate in a reducing atmosphere until said compound decomposes and a nickel-rhenium, cobalt-rhenium or nickel-cobalt-rhenium alloy is formed. .

Although this method can be carried out in various ways, it is preferable to use a means including a solution impregnation process in order to tightly combine the two or three compounds mentioned above.

That is, it is desirable to introduce the compound to be combined or its precursor or derivative onto the carrier in the form of a solution, particularly an aqueous solution.

In such a case, a method may be used in which the carrier is impregnated with individual solutions or a mixed solution of the two or three compounds, a method in which these compounds are simultaneously precipitated from the solution onto the carrier using a precipitant, or two or three compounds are precipitated onto the carrier simultaneously. Any method can be used, such as a method in which one or two of the compounds are first precipitated and then the remaining other components are impregnated.

Specifically, for example, a method of impregnating a nickel compound or a cobalt compound or a mixture thereof and a rhenium compound in the form of a soluble salt onto a carrier from an aqueous solution state;
A precipitant is added to a carrier-dispersed nickel compound or cobalt compound, or a mixed aqueous solution thereof, and then deposited on a nickel, cobalt, or two-component carrier. After drying the resulting metal salt with a carrier, soluble rhenium is added to it. A method of impregnating a compound in an aqueous solution state, using a precipitant, a rhenium compound is uniformly kneaded in an aqueous solution state into a nickel salt cake or (and) a cobalt salt cake produced from a nickel compound or (and) a cobalt compound, and then the rhenium compound is kneaded into a carrier. A method of kneading and adhering it to the top can be implemented.

Nickel and cobalt compounds include nitrates, sulfates, chlorides, and various organic nickel acids; precipitants include ammonium carbonate, ammonium bicarbonate, sodium carbonate, and sodium hydroxide; and rhenium compounds include rhenium hebutoxide and perrhenium. Ammonium acid etc. are common.

When using a carrier, what is generally known as a porous carrier is preferred, such as silica, alumina, diatomaceous earth,
Silica-alumina, activated carbon, magnesia, zirconia,
Any catalyst carrier such as barium carbonate can be used.

After thoroughly drying the mixture of the nickel compound or (and) cobalt compound and rhenium compound produced according to the above embodiment at a temperature of 80 to 120°C, the mixture is heated to 300 to 800°C, preferably 350 to 600°C in a reducing atmosphere.
A catalyst suitable for use in the present invention can be obtained by reduction at a temperature range of several hours or more.

It is also possible to incorporate a step of decomposing these metal compounds in air or nitrogen stream before performing this reduction operation.

At any stage of the above production process, an appropriate binder may be added as needed to form the catalyst into an appropriate shape.

Since the catalyst made in this way has the property of igniting due to rapid catalysis with air, it can be made into a catalyst that is convenient to handle by treating it with carbon dioxide gas or air diluted with inert gas. .

The catalyst stabilized in this way is usually prereduced at 100 to 200° C. in a hydrogen atmosphere before use.

There is no particular restriction on the rhenium content in the composition of the novel catalyst of this invention, but since rhenium is a more expensive component than nickel or cobalt, consideration should be given to the price of the catalyst when determining its content. is necessary.

Therefore, the rhenium content is the atomic ratio of rhenium to nickel or cobalt or their binary system (Re/
It is appropriate to use Ni or Re/Co1 or Re/Ni+Co) in an amount of 0.2 or less, particularly 0.005 or more and 0.1 or less.

On the other hand, the composition ratio of nickel and cobalt in the three-component system of nickel-cobalt-rhenium is not limited at all and can be arbitrarily selected.

Although it is not necessarily clear in what form Ni, Co, and Re exist in the catalyst produced as described above, it is presumed that they all exist as metals and as a solid solution. be done.

2. Hydrogenation The reason why catalytic hydrogenation of ε-caprolactam has not achieved sufficient success in the past is partly because the catalyst was severely poisoned by by-product amino acids, and partly because of the harsh reaction conditions. As mentioned above, this is because the hexamethyleneimine produced in this process is decomposed and ε-caprolactam is polymerized, resulting in a decrease in the yield of hexamethyleneimine.

This problem can be solved by an operating mode of the present invention that involves vapor phase withdrawal of the hexamethyleneimine produced.

According to this mode of operation, water as a by-product is also distilled off together with hexamethyleneimine, so that the by-product of amino acids resulting from the hydrolysis of ε-caprolactam caused by water in the reaction zone is reduced, and therefore, as mentioned above, the by-product of amino acids is reduced. Although the Re-containing catalyst is particularly preferred, it is also possible to use a catalyst that does not have good acid resistance.

Generally, when carrying out the hydrogenation reaction of ε-caprolactam, the water produced by the reaction acts as a catalyst to produce polycaprolactam, so the reaction actually becomes a hydrogenation reaction of polycaprolactam, resulting in a significant reaction. Causes speed reduction.

Therefore, it is preferable to use a suitable solvent when carrying out the hydrogenation reaction.

Suitable solvents for the reaction are ethers such as dioxane,
Hydrocarbons such as diethylene glycol dialkyl ether, such as cyclohexane, delicane, etc., or tertiary amines, such as tri-n-butylamine.

The temperature and pressure that are the conditions for carrying out this hydrogenation reaction vary depending on the amount of catalyst used, but the reaction temperature is usually 100 to 35
It is carried out at 0°C, preferably in the range of 150 to 300°C.

The reaction pressure is not particularly limited, but generally 30 to 500 atm is used.

According to the method of the present invention, by-product water, which is a reaction inhibitor, and hexamethyleneimine, which is a desired product, are simultaneously removed from the reaction zone without going through the industrially extremely disadvantageous step of separating them from the catalyst. It is possible to take it out quickly.

Thus, according to this embodiment, since the by-product water is quickly removed from the reaction zone, catalyst poisoning by the water and the acid decomposed by the water is reduced, and the hydrogenation ability can be maintained for a longer period of time. I can do it.

Furthermore, since hexamethyleneimine is rapidly removed from the reaction zone, sequential side reactions are reduced, and the yield of hexamethyleneimine can therefore be improved.

Another advantage of the process of the invention is that removing the reaction products in the vapor phase has the effect of making it easier to control the reaction temperature.

The hydrogenation reaction of ε-caprolactam to generate hexamethyleneimine and water is an exothermic reaction of about 22 Kcal and 11 moles.

This heat generation can be removed with the latent heat of vaporization of the product.

A preferred embodiment for carrying out the process according to the invention more advantageously consists in carrying out the hydrogenation reaction in the presence of an added solvent and carrying out the vapor phase withdrawal of the reaction product together with this solvent. .

In this way, the solvent not only functions to suppress the polymerization of ε-caprolactam and speed up the reaction, but also functions as a reaction heat control agent and uses its latent heat of vaporization to control the reaction heat. can.

Therefore, the reaction temperature can be maintained at a set value without providing an expensive cooling device within the reactor.

However, it is obvious that it is more preferable that the boiling point of the solvent used in this case is higher than the boiling point of hexamethyleneimine, which is the target product, which is 138° C. (normal pressure).

In this preferred embodiment, any manner of providing solvent to the reaction zone may be used.

One method is to introduce ε-caprolactam into the reaction zone together with the raw material ε-caprolactam.

Another method is to reflux the evaporated solvent to the reactor using a condenser attached to the reactor.

Among these, preferred is an embodiment in which the solvent is introduced into the reaction zone together with the raw material ε-caprolactam.

One of the reasons for this is that the raw material ε-caprolactam is normally solid, and it is almost impossible to continuously feed it in a solid state to a reactor under high pressure, so it must be heated in advance to melt it. However, if a solvent is also supplied, it can be supplied as a solution.

The process according to the invention is carried out under conditions such that the reaction products are removed in the vapor phase, and if this preferred embodiment is followed, the added solvent is also removed in the vapor phase.

The solvent used therefore has a boiling point similar to that of other related hydrogenation products,
For example, water (boiling point 100°C), hexamethyleneimine (1
38° C.), higher than the boiling point of n-hexylamine (130° C.) facilitates the preferential removal of those hydrogenated products, as well as the removal of the solvent in the vapor phase according to this preferred embodiment. If this solvent is evaporated, both water and hexamethyleneimine, which have a boiling point lower than this, will be taken out in the vapor phase.

The evaporation of reaction products and solvent is thus facilitated and controlled by the hydrogen gas supplied in excess to the reactor.

That is, as the amount of hydrogen gas supplied to the reactor increases, the amount of solvent that evaporates also increases.

Therefore, the amount of solvent evaporated from the reaction zone liquid phase is determined by the amount of hydrogen gas fed to the reactor.

The liquid phase feed and the vapor phase effluent can be fed to and withdrawn from the reaction zone, respectively, completely continuously or intermittently.

3. Flow Sheet The continuous hydrogenation process involving vapor phase withdrawal of the hexamethyleneimine produced above can be carried out, for example, as shown in the accompanying drawings.

This device consists of a hydrogenation reactor 1, a condenser 2, and a gas-liquid separator 3.
It consists of a solvent separator 4, a solvent storage 5, and preheaters 6 and 7.

Into a reactor 1 containing a reaction zone liquid phase containing a suitable catalyst, in particular a catalyst according to the invention, suspended therein, the raw material ε-caprolactam is introduced through a tube 18, and the solvent is introduced through a tube 16, after being preheated in a preheater 7. It is fed via tube 9.

The dissolution of ε-caprolactam in the solvent can be carried out in the preheater 7, but it can also be carried out in a separate device (not shown).

Hydrogen gas is preheated in a preheater 6 and then supplied to the reactor 1 through a tube 8.

Reactor 1 can be equipped with a suitable stirring device.

The vapor phase flowing out of the reactor 1 passes through a pipe 10 to a condenser 2.
The oil is supplied to a gas-liquid separator 3 to condense the oil, and is further sent to a gas-liquid separator 3 through a pipe 11 to separate a gas phase and a liquid phase.

This gas phase, consisting mainly of hydrogen, is partially discharged out of the thread via tube 19 and the remainder is recycled to reactor 1 via tube 12.

On the other hand, the liquid phase is sent to the solvent separator 4 via a pipe 13 to separate the solvent and the reaction product, and the reaction product is sent to the purification system via a pipe 14.

The separated solvent is sent via pipe 15 to storage device 5 .

This can be sent back to reactor 1 via line 16.

The illustrated apparatus can be modified in various ways.

For example, in the illustrated apparatus, the vapor phase oil from the reactor is completely condensed in a condenser (total condenser), the solvent is separated in a solvent separator, and then recycled to the reactor. The vapor phase is partially condensed in a partial condenser to liquefy the high boiling point solvent and refluxed to the reactor, and the vapor phase after separation of the enzyme can be subjected to cooling, separation, and purification operations.

4. Examples The present invention will be explained in more detail by referring to reference examples below.

Note that this invention is not limited by these reference examples unless they go beyond the gist of the invention.

Reference example 1 Cobalt nitrate (Co (NO3) 2 ・6H20)
Add 240 g of ammonium bicarbonate (NH4HCO3) to 1200 g of 3001 in distilled water.
When an aqueous solution of 1 dissolved in distilled water is added dropwise under stirring, reddish-purple basic cobalt carbonate precipitates.

The precipitate is filtered off and the cake is washed with distilled water to obtain a basic cobalt carbonate salt cake.

The cobalt content in this cake was 12.5% by weight.

Is this cake 23.6r? (Catalyst-1), 0.18
2f (catalyst-2), 0.363 (catalyst-3), 0.72
79C catalyst-4), 1.211S' (catalyst-5), 1.
817 t (catalyst-6,) of rhenium hebutoxide (Re 20□) are added in the form of an aqueous solution, and after thorough kneading, 5.91 g of powdered barium carbonate is added.

The obtained slurry is heated to around 80°C, kneaded and dried, and then dried at 80 to 120°C for 12 hours.

The powder thus obtained was heated in a hydrogen stream for 4 hours.
Reduce at 50°C for 3 hours.

After the catalyst that has undergone hydrogen reduction is cooled to 150° C., the hydrogen flow is changed to a carbon dioxide gas flow and left overnight.

Gradually bring the carbon dioxide treatment solution into contact with air diluted with nitrogen.

In this case, the catalyst layer generated heat, but the temperature was kept from exceeding 50°C.

The weight ratio of cobalt to barium carbonate in the thus prepared catalyst was 1:2, and the atomic ratio of rhenium to cobalt was as shown in Table 1.

If? These catalysts -1 to -6 were placed in a 100cc capacity electromagnetic stirring autoclave. , ε-caprolactam as IO
f. 30% of diethylene glycol dibutyl ether was charged as a solvent, and the reaction was carried out by contacting with hydrogen for 1 hour at a reaction pressure of 120 atm and a reaction temperature of 250° C. while maintaining the stirring speed at 1100 rpm.

After the reaction was completed, the reactant was separated from the catalyst and subjected to gas chromatographic analysis using an internal standard method.

The results are shown in Table-1.

Reference example 2 Nickel nitrate (Ni(NO3)2.6 H20) 30
12 ammonium bicarbonate (MH4HCO3) 240 S' was dissolved in an aqueous solution of 0 g dissolved in 24 of distilled water.
When an aqueous solution of 001 dissolved in distilled water is dropped under stirring, greenish-white basic nickel carbonate precipitates out.

The precipitate is filtered off and the cake is washed with distilled water to obtain a basic nickel carbonate cake.

The nickel content in this cake was 12.2% by weight.

Og (catalyst-7), 0.72 to this cake 24.6S'
After adding rhenium heptoxide of 7f (catalyst-8) in the form of an aqueous solution and thoroughly kneading, powdered diatomaceous earth 3
Add 1.

The obtained slurry is cross-dried while being heated to around 80°C, and then dried at 80 to 120°C for 12 hours.

From the powder thus obtained, the atomic ratio of one rhenium to nickel was determined by the operation shown in Reference Example 1 below.
As shown in Figure 2, a catalyst was obtained in which the weight ratio of nickel to diatomaceous earth was 1:1.

Using the catalyst thus crushed, a reaction was carried out using ε-caprolactam as a raw material under the same conditions as in Reference Example 1, and the results shown in Table 2 were obtained.

Example 1 Reference example 1 was placed in a 300cc autoclave with electromagnetic induction stirring.
3 g of catalyst-4 obtained by the procedure shown in , 30 g of ε-caprolactam, and 150 g of diethylene glycol diethyl ether as a solvent were charged, the reaction pressure was 120 atm, the reaction temperature was 25'O'C, and the stirring speed was 1000 rp.
The catalytic hydrogenation reaction was started under conditions of m.

Thirty minutes after the start of the reaction, the reaction product and solvent together with hydrogen gas were extracted from the vapor phase until the reaction pressure reached 80 atm, cooled and condensed, and collected in liquid form.

Hydrogen was replenished to compensate for the decrease in reaction pressure, and the reaction was continued at a predetermined reaction pressure of 120 atm.

After performing this operation every 30 minutes, a total of 6 times,
The amount of liquid product collected was 165 g.

When this product was analyzed by gas chromatography, it was found that 1
It contains 3.1% by weight of hexamethyleneimine, which corresponds to a yield of 75% by mole based on the charged ε-caprolactam.

Example 2 In the illustrated apparatus, a reactor system was used in which the solvent was condensed and refluxed using a partial condenser.

The reactor has an inner diameter of 110 mm and a height of 230 mm, and is of the type that performs stirring by induction rotation.The partial condenser directly connected to this reactor has an inner diameter of 30 mm and a length of 550 mm.
It is of mm.

The reaction is carried out at a pressure of 120 atmospheres.

Reactor 1 was charged with 30 g of catalyst-4 and 1000 g of solvent diethylene glycol diethyl ether in advance.
The reaction temperature was kept constant at 210°C, and the rotation speed was 8.
Stirring is carried out at 0.00 rpm.

Then, hydrogen gas was introduced from tube 8 at a rate of 170 ONL/hour, and ε-caprolactam preheated to 100° C. was introduced from tube 9 at 15 g/hour and diethylene glycol as a solvent.
It is fed to reactor-1 at a rate of 5 g/hour.

The vapor flowing out from the reactor 1 is cooled and condensed in a condenser 2, and unreacted hydrogen gas is separated in a gas-liquid separator 3.

Liquid is produced from the gas-liquid separator 3 at a rate of 100 g/hour.

The liquid composition in tube 13 was analyzed and found to be 12% by weight of hexamethyleneimine, 0.5% by weight of n-hexylamine, 83% by weight of diethylene glycol diethyl ether, and 3.5% by weight of water.
% by weight and 1% by weight of other side organisms, and the yield of hexamethyleneimine from ε-caprolactam was 85 mol%.

[Brief explanation of drawings]

The drawing is a flow sheet showing an example of a reaction system suitable for carrying out the method according to the invention. 1... Hydrogenation reactor, 8... Hydrogen gas supply pipe, 9... Liquid phase feed (ε-caglolactam + solvent) supply pipe, 10...・・Vapor phase extraction material (hexamethyleneimine + water (+ solvent)) extraction pipe.

Claims (1)

[Claims] 1 In a method for producing hexamethyleneimine by catalytic hydrogenation of ε-caprolactam, raw material ε-caprolactam is supplied in a liquid phase to a reaction zone liquid phase maintained at a substantially constant temperature, and the reaction product is heated to an excess of hydrogen gas. 1. A method for producing hexamethyleneimine, characterized in that it is removed from a reaction zone in the vapor phase together with a minute amount.