JPS5810374B2 - Amin no Seihou - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION This invention relates to a method for producing amines by liquid phase hydrogenation of nitriles.

Conventionally, when producing amines industrially, nitrile was hydrogenated using a fixed bed catalyst in the presence of liquid ammonia and hydrogen, but this method resulted in deactivation, crushing, and powdering of the catalyst. Scratching was considered to be a major problem in industry.

In other words, catalysts in which active metals are supported on carriers such as alumina, silica, and pumice are generally less prone to crushing and pulverization under a wide range of reaction conditions for hydrogenation of many organic compounds. Despite having excellent mechanical strength, this catalyst is not always stable when applied to liquid-phase hydrogenation of nitriles, and the catalyst often undergoes deterioration due to the effects of reactants and media. The catalyst was crushed and powdered.

As a result, partial blockage of the flow-through reactor causes uneven flow of the reaction fluid and a drop in reaction rate, and furthermore, complete blockage of the reactor, conduits, etc. causes an increase in differential pressure, resulting in the operation being shut down in a short period of time. There was a drawback that it had to be done.

In addition, catalysts prepared from cobalt oxide and nickel oxide cannot maintain their activity continuously for a long period of time, and the catalyst deactivates rapidly, so the reaction is often interrupted and the catalyst is reactivated. In particular, this was a hindrance to continuous industrial operation.

Furthermore, although the catalyst prepared from iron oxide itself has excellent mechanical strength and is not easily crushed or powdered, it is used as a catalyst for the hydrogenation of nitrile. When carrying out hydrogen reduction treatment for activation prior to this, a significant decrease in mechanical strength occurred, making it impossible to operate continuously for a long period of time.

The purpose of this invention is to provide a fixed bed catalyst with excellent activity and durability that does not cause catalyst deactivation, crushing, or powdering even when used continuously for a long period of time when nitrile is subjected to liquid phase hydrogenation. There is a particular thing.

Another object of the present invention is to prevent clogging of reactors, conduits, etc. caused by crushing and powdering of the catalyst, and to maintain stable continuous operation for a long period of time.

The inventors conducted various studies to achieve the above object using iron oxide as a catalyst, and as a result, they arrived at the present invention.

That is, in this invention, the capacity ratio of CO/CO2 is 1/2.
Iron oxide is heat-treated at 560°C or higher in a mixed gas atmosphere of carbon monoxide and carbon dioxide with a molecular weight of 130°C to 130°C.
A fixed bed catalyst prepared by sintering or melting at 0°C or higher is activated by hydrogen reduction treatment at 200 to 600°C, and nitrile is used for liquid phase hydrogenation in the presence of ammonia and hydrogen. This paper relates to a method for producing amines.

In the method of this invention, any iron oxide such as iron sesquioxide, triiron tetroxide, etc. can be used as the catalyst raw material.

Such iron oxide can be obtained, for example, by precipitating iron hydroxide from an iron salt solution and then calcining it, or by thermally decomposing iron organic salts or cyanide complex salts, but generally can be obtained by oxidizing and melting metallic iron in an oxygen stream.

Furthermore, a non-fusible, non-reducible co-catalyst component may be added to the iron oxide, such as aluminum oxide, thorium oxide, uranium oxide, zirconium oxide, etc. can be given.

These promoter components may be mixed with the iron oxide in powder form (or may be in the form of soluble salts and added as a solution or gel).

When these co-catalyst components are used, their proportions are suitably up to about 10% by weight based on the iron oxide.

The fixed bed catalyst used in the method of this invention is capable of converting iron oxide to 56% in a mixed gas atmosphere of carbon monoxide and carbon dioxide.
It is prepared by heating at 0°C or higher, sintering or melting at 1300°C or higher, cooling to obtain an iron oxide ingot, crushing and sizing it, and subjecting it to hydrogen reduction treatment at 200 to 600°C. Ru.

The CO/CO2 volume ratio of the mixed gas of carbon monoxide and carbon dioxide is suitably in the range of 1/250 to 1, particularly preferably in the range of 1/10 or less.

Further, this mixed gas may be diluted with an inert gas such as nitrogen, helium, or argon.

Iron oxide has a concentration of 1300 in such a mixed gas atmosphere.
℃ to the melting point of iron oxide, but even during the heating process from 560℃ to reach this temperature and the cooling process from this temperature to 560℃, carbon monoxide It is important that the heat treatment be carried out for a certain period of time in a mixed gas atmosphere of carbon dioxide and carbon dioxide.

It should be noted that it is not necessary to maintain the mixed gas atmosphere as described above during the entire period of the heating process and cooling process (although it is possible to hold the gas mixture in an atmosphere of air, nitrogen, carbon dioxide, etc. for part of the period). No problem.

Note that it is not necessary to keep the temperature increase rate and the temperature decrease rate constant, and these optimum rates cannot be determined uniquely because they vary depending on the raw material iron oxide and the composition of the mixed gas atmosphere.

The important thing is to provide enough time for the iron oxide and mixed gas to react.
The temperature is to be maintained at 560° C. or higher, and in practical terms, the appropriate heating rate and cooling rate are 10° C./h or higher, preferably 50 to 500° C./h.

Further, the sintering and melting time is usually 5 hours or more.

A catalyst is prepared by crushing the thus obtained iron oxide lump using a crusher, sieving it, and sifting it to an appropriate particle size that will allow the subsequent hydrogen reduction treatment to be carried out satisfactorily.

Next, prior to the hydrogenation reaction, the catalyst prepared here is treated at 200 to 600°C, preferably 350 to 500°C, in a gas containing hydrogen as the main component, so that most of the iron oxide is made of elemental iron. It is reduced and activated until it becomes .

It is desirable that substantially no moisture be present in this reduction treatment, and therefore it is advantageous to carry out the reduction treatment while circulating a large amount of hydrogen.

Although this hydrogen reduction treatment proceeds satisfactorily under normal pressure, it can also be further accelerated under increased pressure.

The catalyst prepared and activated in this way has excellent durability even under harsh hydrogenation reaction conditions in the presence of liquid ammonia and hydrogen, and can be used in both batch and continuous reactors. However, in order to take advantage of its characteristics, it is particularly advantageous to use it as a fixed bed catalyst in a flow-through type continuous reactor.

The method of the present invention uses such a fixed bed catalyst to produce an amine by carrying out liquid phase hydrogenation of a nitrile in the presence of ammonia and hydrogen.

As the nitrile, any nitrile known to be capable of being converted into an amine by hydrogenation can be used.

Preferred nitriles include: For example, adiponitrile,
α・ω-Dicyanodecane, β-anilinopropionitrile, N-β-cyanoethylcyclohexylamine, ε-
Examples include aliphatic nitriles such as aminocapronitrile, valeronitrile, sepaconitrile, and stearonitrile, and aromatic nitriles such as benzonitrile, inphthalonitrile, and terephthalonitrile.

The reaction temperature for hydrogenation is 60-200°C, especially 80-17°C.
The temperature is preferably 0°C, and the reaction pressure is 100kg/crrr.
G or more, especially 200 to 300 kg/crAG is preferable.

In general, the reaction rate of nitrile hydrogenation is improved by increasing the reaction temperature, but undesirable by-products such as secondary amines increase rapidly, reducing amine selectivity, and catalyst crushing and powdering. However, when using the fixed bed catalyst prepared by the method of this invention,
Even at high temperatures, the formation of such by-products was minimal, and hardly any crushing or pulverization of the catalyst was observed.

Furthermore, this catalyst has a very high activity and can hydrogenate nitrile at an industrially sufficient reaction rate even if the reaction temperature is maintained at a low temperature such as 100°C or less.
It is possible to further reduce by-products, crushing of the catalyst, and pulverization.

The proportions of nitrile, liquid ammonia and hydrogen can vary over a wide range, but typically 1 mole of nitrile: 10-100 moles of liquid ammonia, 2 moles of hydrogen.
It is appropriate to use 0 to 80 mol.

Excess liquid ammonia can be recycled after being separated from the reaction product, and in some cases, a part of the reaction product may be recycled to the reactor together with the liquid ammonia.

If the amount of liquid ammonia used is too large, the reaction rate will be reduced and the amount of ammonia circulated will be increased, while if it is too small, the amine selectivity will be reduced.

In some cases, liquid ammonia or hydrogen may be used after being diluted with a suitable inert gas.

When liquid phase hydrogenation of nitriles was carried out according to the method of this invention, the fixed bed catalyst was mostly deactivated and crushed.
Stable continuous operation can be performed for a long period of time without causing powdering.

Next, examples and comparative examples of the present invention will be shown.

Note that all parts represent parts by weight.

Examples 1 to 3 and Comparative Examples 1 and 2 After thoroughly mixing 97 parts of iron oxide powder consisting essentially of triiron tetroxide and 3 parts of γ-alumina powder using a crusher, the mixture was packed into an alumina crucible, Charge the electric furnace and heat up at a rate of 200.
The temperature was raised to 1400° C. at a rate of 1400° C./h, held at this temperature for 5 hours for sintering, and then allowed to cool to room temperature at a cooling rate of 200° C./h.

During the period when the temperature inside the electric furnace was maintained at 560°C or higher, a mixed gas of carbon monoxide and carbon dioxide was circulated so that the atmosphere inside the electric furnace was maintained at a volume ratio of CO/CO2<l. .

The obtained iron oxide lump was crushed with a crusher, and 8 to 14 mesh pieces were sieved to prepare a catalyst.

Five parts of the obtained catalyst were sealed in a stainless steel pressure tube, and after purging with nitrogen, hydrogen was heated at 470°C and 6.5 kg/cr;
It was activated by passing 48 copies of tG.

The thus prepared and activated catalyst was transferred to a 0.51 volume rotary stirred autoclave without coming into contact with air, containing 20 parts of adiponitrile and 13 parts of liquid ammonia.
Pour 0 parts, seal, and pressurize hydrogen at 140℃, 25℃.
The hydrogenation reaction was carried out while adding hydrogen until no hydrogen was absorbed at 0 to 290 kg/cvlG.

After the reaction was completed, ammonia was vaporized and released, the remaining contents were taken out from the autoclave, the catalyst was filtered off, and after washing with methanol, the catalyst strength and powdering rate were measured.

On the other hand, the reaction products were analyzed by gas chromatography to measure the yields of hexamethylenediamine and by-produced hexamethyleneimine.

For comparison, the catalyst strength and yield are also shown when air and carbon dioxide were used instead of the mixed gas of carbon monoxide and carbon dioxide.

These results are summarized in the table below.

Example 4 In Example 1, the heating period up to 1400°C and 1
During the period of temperature drop to below 400℃, carbon dioxide is circulated in the electric furnace, and only during the constant temperature holding period of 1400℃, monoxide is maintained so that the atmosphere inside the electric furnace is maintained at a volume ratio of CO/CO2 = 1/19. carbon and carbon dioxide.

Catalysts of 8 to 14 meshes were prepared in the same manner as in Example 1, except that a mixed gas with elementary gas was passed through, and activated to perform a hydrogenation reaction of adiponitrile.

The strength of the catalyst after the reaction was 6 kg, and almost no powdering of the catalyst was observed.

Reaction time 70M. The yield of hexamethylene diamine was 99
．． It was 5%.

Furthermore, when nitrogen was similarly passed during the temperature rising period and the temperature falling period, substantially the same catalyst strength and hexamethylene diamine yield as above were obtained.

Example 5 97 parts of iron oxide powder consisting essentially of triiron tetroxide and 3 parts of γ-alumina powder were thoroughly mixed and then filled into a crucible.

This crucible was placed in another slightly larger crucible, the inner crucible was loosely covered to allow contact with the outside air, and carbon grains were placed on top to fill the outer crucible.

This crucible was placed in an electric furnace and sintered in an air atmosphere.

The reaction conditions were the same as in Example 1.

When this catalyst (8 to 14 meshes) was used in a hydrogenation reaction of adiponitrile, the strength of the catalyst after the reaction was 8 kg, and almost no pulverization of the catalyst was observed.

The yield of hexamethylene diamine in order of reaction time 90 is 9
It was 8.8%.

Example 6 After thoroughly mixing 97 parts of iron oxide powder consisting essentially of triiron tetroxide and 3 parts of γ-alumina powder, the mixture was packed in a crucible and charged into a Tammann furnace.

Electricity was applied to the carbon heating element and the mixture was heated to 1500° C. for 5 hours.

During heating, the heating element was consumed by contact with air, and the gas generated from the furnace contained carbon monoxide.

The obtained catalyst was sized into 4 to 10 meshes and activated by treatment with hydrogen at 470°C.

When this catalyst was used in a hydrogenation reaction of adiponitrile, the strength of the catalyst after the reaction was 12 kg, and almost no powdering of the catalyst was observed.

The yield of hexamethylenediamine at a reaction time of 130a+m was 96.6%.

Example 7 In Example 1, the heating period up to 1400°C and 1
During the temperature drop period to 400℃ or below, nitrogen is passed through the electric furnace, and carbon monoxide is supplied so that the atmosphere inside the electric furnace is maintained at the capacity ratio Co/C02 = 1/19 only during the constant temperature holding period of 1400℃. A catalyst of 8 to 14 meshes was prepared in the same manner as in Example 1, except that a mixed gas of carbon dioxide and carbon dioxide was passed through.
Activated.

5 parts of this catalyst was transferred to a rotary stirring autoclave without coming into contact with air, 35 parts of benzonitrile and 130 parts of liquid ammonia were added, and the mixture was pressurized with hydrogen to a temperature of 200 to 250 parts.
kg/crttG, reacted at 140°C for 140m.

After the reaction was completed, the ammonia was vaporized and the remaining contents were taken out, the catalyst was separated and washed with methanol.
The catalyst strength was 6 kg, and no powdering of the catalyst was observed.

On the other hand, gas chromatography analysis of the reaction product revealed that the yield of benziamine was 98.4% and the yield of by-product dibenzylbumine was 0.4%.

Claims (1)

[Claims] 1 Iron oxide is heat treated at 560°C or higher and sintered or melted at 1300°C or higher in a mixed gas atmosphere of carbon monoxide and carbon dioxide with a CO/CO2 volume ratio of 1/250 to 1. The prepared fixed bed catalyst was heated to 200-600℃.
A method for producing an amine, which is activated by a hydrogen reduction treatment and used for liquid phase hydrogenation of a nitrile in the presence of ammonia and hydrogen.