MXPA00001787A - Method for producing aliphatic alpha, omega-amino nitriles - Google Patents

Abstract

The invention relates to a method for producing aliphatic alpha, omega-amino nitriles in the presence of a catalyst composed of (a) iron or an iron based compound or a mixture thereof, (b) 0.01 to 5 wt.%in relation to (a) a promotor based on 2, 3, 4, or 5 elements selected from the group comprising aluminum, silicium, zirconium, titanium and vanadium and (c) 0 to 0.5 wt.%in relation to (a) a compound based on an alkaline metal or alkaline-earth metal. The inventive method is characterized in that the applied aliphatic alpha, omega-amino dinitrile contains 1.0 wt. ppm or more phosphor. Catalysts are obtainable through the reduction and optional successive passivation of a magnetite, whereby the catalysts have a BET surface of 3 to 10 m2/g, a total pore volume of 0.05 to 0.2 ml/g, an average pore diameter of 0.03 to 0.1 mm and a pore volume portion in the range of 0.01 to 0.1 mm of 50 to 70%.

Description

PROCEDURE FOR OBTAINING ALPHA-MEGA-ALYNATIC AMINONITRILS Description The present invention relates to a process for the preparation of aliphatic α, α-aminonitriles in the presence of a catalyst, as well as to catalysts which are suitable for hydrogenation.

DE-A 44 468 93 discloses a process for the preparation of aliphatic alpha, -mega-aminonitriles by partial hydrogenation of alpha, aliphatic oxime-dinitriles at high temperature and high pressure, in the presence of a solvent and a catalyst, where a catalyst containing (a) a compound based on a metal, selected from the group, comprising nickel, cobalt, iron, ruthenium and rhodium, and (b) from 0.01 to 25, preferably from 0.1 to 5% by weight, with respect to (a), of a promoter based on a metal, selected from the group, comprising palladium, platinum, iridium, osmium , copper, silver, gold, chromium, molybdenum, tungsten, manganese, rhenium, zinc, cadmium, lead, aluminum, tin, phosphorus, arsenic, antimony, bismuth and rare earth metals, as well as (c) from 0 to 5, preferably from 0.1 to 3% by weight, with respect to (a), of a compound based on an alkali metal or a metal-air-metal, it being necessary that component (a) does not either iron-based or consisting of iron and a metal, selected from the group, comprising cobalt, ruthenium and rhodium, when (b) is a promoter based on a metal, selected from the group, comprising titanium, manganese, chromium and molybdenum, and furthermore being precise, that when a compound based on only ruthenium or rhodium or ruthenium and rhodium or nickel and rhodium is used as component (a), the promoter (b) may be dispensed with if desired.

The disadvantage of this process is that secondary products are formed that are difficult to separate from alpha, omega-aminonitriles, such as, for example, 6-aminocapronitrile or possibly other valuable products, such as adipoxin and hexamethylenediamine, if available. 6-aminocapronitrile used as alpha, o-methaneditrile.

Thus, they are formed, for example, in the hydrogenation of adiponitrile, 6-aminocapronitrile and hexamethylenediamine in various amounts, for example, l-amino-2-cyanocyclopentene (ICCP), 2-aminomethylcyclopentylamine (? *? MCPA), 1,2- diaminocyclohexane (DCH) and bishexamethylenetriamine (BHMTA). From US-A 3 696 153 it is known that AMCPA and DCH are difficult to separate from he-xamethylenediamine, In addition, the residence time of the catalysts in this process is not entirely satisfactory.

The earlier German patent application, 196 36 765.4, describes a similar procedure to that of the present patent application, but in the procedure described in 196 36 765.4 the selectivity of 6-aminocapronitrile (ACN) depends on the age (time of permanence) of the catalysts used, unless phosphorus is previously separated in adi-podinitrile (gDNA). But the separation of phosphorus is technically more complicated and it is desirable to abstain from this stage.

It is therefore an object of the present invention to provide a process for the preparation of aliphatic alpha, -mega-aminonitriles by the partial hydrogenation of alpha, aliphatic oxime-dinitriles, in the presence of a catalyst, the process of which does not have the aforementioned disadvantages, and allow to prepare alpha, ormega-aminonitriles with high selectivity in a technically simple and economical way, have long residence times with practically unchanged conversions and continuously high selectivities in alpha, ormega-aminonitriles.

Therefore, a procedure was found for the preparation of aliphatic alpha, ormega-araneonitriles by partial hydrogenation of alpha, aliphatic oxime-dinitriles, in the presence of a catalyst, containing (a) iron or an iron-based compound or mixtures thereof, and (b) from 0.01 to 5% by weight, with respect to (a), of a promoter based on 2,3,4 or 5 elements selected from the group comprising aluminum, silicon, zirconium, titanium and vanadium, as well as (c) from 0 to 0.5% by weight, with respect to (a), of a compound based on an alkali metal or alkaline earth metal, whose method is characterized in that the alpha, oxime-dinitrile used contains 1, 0 ppm by weight or more of phosphorus.

In addition, catalysts were found, which can be obtained by reduction and possibly subsequent passivation of a magnetite, which contain (a) iron or an iron-based compound or mixtures thereof. (b) 0.01 to 5% by weight, with respect to (a), of a base promoter of 2, 3; 4, or 5 elenments selected from the group comprising aluminum, silicon, vanadium, titanium and cirion, (c) 0 to 0.5% by weight, with respect to (a), of a compound based on an alkali metal or alkaline earth metal. the catalysts having a BET surface area of 3 to 10 m2 / g, a total pore volume of 0.05 to 0.2 ml / g, an average pore diameter of 0.03 to 0.1 μm and a volumetric ratio of pores from 0.01 to '0.1 μm from 50 to 70%.

Preferred catalyst precursors are those, in which the component (a) contains up to 90 to 100% by weight, preferably 92 to 99% by weight, based on (a), of iron oxides, iron hydroxides, oxyhydroxides of iron or its mixtures. As such, for example, iron oxide (III), iron oxide (II, III), iron (II) oxide, iron (II) hydroxide, iron (III) hydroxide or oxyhydroxide are suitable. of iron, such as, for example, FeOOH. Oxides, hydroxides or iron oxihydroxides of natural or synthesized origin, such as magnetite, can be used, which in an ideal case can be described as Fe0, limonite, which in an ideal case can be described as Fe03 • H0, or atita, which in ideal case it can be described as Fe20.

Preferred catalyst precursors are, in addition, those in which component (b) contains from 0.01 to 5% by weight, preferably 0.1 to 4% by weight, especially 0.1 to 2% by weight of a promoter based on 2,3,4 or 5 elements selected from the group comprising aluminum, zirconium, silicon, titanium and vanadium.

Preferred catalyst precursors are, in addition, those in which component (c) contains 0 to 0.5% by weight, preferably 0.02 to 0.2% by weight of an alkali metal-based compound or alkaline earth, preferably selected from the group comprising lithium, sodium, calcium, rubidium, cesium, magnesium and calcium.

The catalysts can be mastic catalysts or support catalysts. Suitable support catalysts are, for example, porous oxides, such as aluminum oxide, silicon dioxide, aluminum silicones, lanthanide oxide, titanium dioxide, zirconium dioxide, magnesium oxide, zinc oxide and zeolites, as well as carbon active or mixtures thereof.

Generally, the preparation is carried out in such a way that the precursor of the component (a) is precipitated, if desired, together with the precursors of the promoter components (b), and, if desired, with the precursors of the micro components (c), in the presence or absence of support materials (depending on the type of catalyst to be obtained), the catalyst precursors are made in macaroni or tablets, if desired, dried and then calcined. The support catalysts are generally obtained by impregnating the support with a solution of the components (a), (b) and optionally (c), the individual components can be added simultaneously or successively, or by spraying the components (a), optionally (b) ) and (c) on the support according to known methods.

Suitable precursors of components (a) are, as a rule, the very soluble salts of iron, such as nitrates, chlorides, acetates, formates and sulfates, preferably nitrates.

Suitable precursors of the components (b) are the salts which are very soluble in water or the complex salts of the aforementioned metals and semimetals, such as nitrates, chlorides, acetates and sulfates, preferably the nitrates.

As precursors of the components (c), generally well-soluble salts are suitable in water of the aforementioned alkali and alkaline earth metals, such as hydroxides, carbonates, nitrates, chlorides, acetates, formates and sulphates, preferably the hydroxides and carbonates .

The precipitation is generally carried out from aqueous solutions, alternatively by adding precipitation reagents, modifying the pH value, or by modifying the temperature.

Generally, the obtained catalyst mass is dried at temperatures of, generally, 80 to 150, preferably 80 to 120 ° C.

The calcination is usually carried out at temperatures of 150 to 500, preferably 200 to 450 ° C in a gas stream from air or nitrogen.

After calcination, the mass of the catalyst obtained is generally exposed to a reducing atmosphere ("activation"), for example by subjecting it to a temperature of 200 to 500, preferably 250 to 400 ° C for 2 to 24 hours at an atmosphere of hydrogen or a mixture of gases containing hydrogen and an inert gas, such as, for example, nitrogen. The catalyst charge here preferably is 200 1 by 1 of catalyst.

Advantageously, activation of the catalyst is carried out directly in the synthesis reactor, since in this way it is not necessary to carry out a generally necessary intermediate step, namely the passivation of the surface at temperatures of, normally, 20 to 80, preferably 25. at 35 ° C by oxygen-nitrogen mixtures, such as, for example, air. Activation of passivated catalysts is preferably carried out in the synthesis reactor at a temperature of 180 to 500, preferably 200 to 350 ° C in an atmosphere containing hydrogen.

The BET surface of the catalysts according to the invention, determined by adsorption of N2 according to DIN 66131, ranges from 3 to 10 m2 / g.

The total pore volume of the catalysts according to the invention, determined by Hg porosimetry according to DIN 66133, ranges from 0.05 to 0.2 ml / g.

The average diameter of the pores of the catalysts according to the invention, calculated from the distribution of pore volumes, which is determined by Hg porosimetry according to DIN 66133, varies from 0.03 to 0.1 μm.

The volumetric pore ratio with a dimension of 0.01 to 0.1 μm of the catalysts according to the invention, deduced from the distribution of pore volumes that has been determined by Hg porosimetry according to DIN 66133, amounts to 50 to 70% in volume.

The catalysts can be used as fixed-bed catalysts in exhaustion or run-off processes or as suspension catalysts.

The starting materials used are alpha, aliphatic dinitriles of the general formula I in the process according to the invention.

NC- (CH2) n-CN wherein n is an integer from 1 to 10, especially 2, 3, 4, 5 and 6. Especially preferred compounds I are the dinitryl of succinic acid, glutaric acid dinitrile, adipic acid dinitrile (" adiponitrile "), pimelic acid dinitrile and suberic acid dinitrile (" suberonitrile "), especially adiponitrile.

The dinitriles of the general formula I contain 1.0ppra by weight or more phosphorus. The dinitriles are suitable, whose content of phosphorus, determined by self-monitoring spectroscopy after the acid disintegration of the DNA, varies from 1 to TOO ppm by weight, preferably from 1 to 20 ppm by weight, with respect to dinitrile I or the dinitrile mixture containing dinitriles of the general formula I. The phosphorus can be present in multiple forms in the mixture with the dinitrile I or the dinitriles I, for example, as organic phosphite or phosphine or their corresponding decomposition products or derivatives. Dinitriles I, obtained from alpha, omega-dienes with hydrocyanic acid, have proved very useful in the manner described, for example, in eissermel, Arpe, Industrielle Organische Chemie, 2a. edition, pages 233 to 234 (1978) -. The alpha, omega-adiponitrile, obtained by the addition of hydrocyanic acid to 1,3-butadiene, as described, for example, in Weissermel, Arpe, Industrielle Organische Chemie, 2a, is especially pooled. edition, pages 233 to 234 (1978).

According to the process of the invention, the dinitriles I described above are hydrogenated, preferably in the presence of a solvent, using a partial catalyst, giving alpha loa, oxamegaminitriles of the general formula II NC- (CH2) n-CH2-NH2 II, having n the above indicated meaning. Especially preferred aminonitriles II are those, in which n has the value 2, 3, 4, 5 or 6, especially 4, that is, the nitrile of 4-aminobutanoic acid, 5-aminopentanoic acid nitrile, 6-nitrile aminohexanoic ("6-aminocapronitrile"), 7-aminoheptanoic acid nitrile and 8-aminoocannic acid nitrile, with 6-aminocapronitrile being preferred.

When the reaction is carried out in a suspension, a temperature of from 40 to 150, preferably from 50 to 100, most preferably from 60 to 90 ° C, is generally chosen; the pressure is generally from 2 to 30, preferably from 3 to 30, most preferably from 4 to 9 MPa. The residence times depend, substantially, on the desired yield, selectivity and conversion; generally, the residence time is chosen in such a way that a maximum of yield is reached, for example, in 50 to 275, preferably 70 to 200 min.

In the suspension method, ammonia, amines, diamines and triamines with 1 to 6 carbon atoms, such as trimethylamine, triethylamine, tripropylamine and tributylamine or alcohols, especially methanol and ethanol, most preferably ammonia, are preferably used as the solvent. Conveniently, a dinitrile concentration from 10 to 90, preferably from 30 to 80, most preferably from 40 to 70% by weight, is chosen with respect to the sum of ditrile and solvent.

The amount of catalyst is generally chosen in such a way that it amounts to 1 to 50, preferably 5 to 20% by weight, based on the amount of dinitrile used.

The hydrogenation by suspension can be carried out batchwise or, preferably, continuously, generally, in the liquid phase.

It is also possible to carry out the partial hydrogenation in discontinuous form in a fixed-bed reactor by depletion or exhaustion, usually selecting a temperature of 20 to 150, preferably 80 to 120 ° C and a pressure of generally 2 to 40, preferably from 3 to 30 MPa Preferably, the partial hydrogenation is carried out in the presence of a solvent, in particular ammonia, diamines, diamines and triamines having 1 to 6 carbon atoms, such as, for example, trimethylamine, triethylamine, tripropylamine and tributylamine or alcohol, preferably methanol and ethanol, most preferably ammonia. In a preferred variant, an ammonia content of 1 to 10, preferably 2 to 6 g per g of adiponitrile is chosen. Most preferably, a catalyst loading of 0.1 to 2.0, preferably 0.3 to 1.0 kg of adiponitrile / l * h is chosen here. Here, too, it can be regulated specifically, varying the residence time, the conversion and with it the selectivity.

The partial hydrogenation can be carried out in a reactor which is particularly suitable for this purpose.

In the hydrogenation, a mixture is obtained which contains 6-ami-nocapronitrile, hexamethylenediamine and adiponitrile.

The separation of 6-aminocapronitrile, hexamethylenediamine and a portion substantially containing adiponitrile from the mole can be carried out in a manner known per se, preferably by distillation, for example according to DE-A 195 002 22 or German patent application 19 548 289.1, simultaneously or successively.

The adiponitrile obtained according to the process of the invention can again be used for partial hydrogenation by giving hexamethylenediamine and 6-aminocapronitrile, and it is possible to prevent an enrichment of byproducts by means of an acid treatment of the ACN, which prevents obtaining according to the hexamethylenediamine specification. and / or 6-aminocapronitrile and / or negatively affect partial hydrogenation.

According to the process of the invention, alpha, omega-aminonitriles are obtained in good selectivities. Furthermore, the catalysts used according to the invention have a considerably longer residence time with the same high selectivities in ACN, compared with comparable catalysts of the prior art. Alpha, omega-aminonitriles are important starting products for obtaining cyclic lactams, especially 6-aminocapronitrile for the preparation of caprolactam.

In the examples they mean: DNA = adiponitrile ACN = 6-aminocapronitrile HMD-hexamethylenediamine DCH = cis + trans-1,2-diaminocyclohexane AMCPA = l-amino-2-aminomethylcyclopentan-? Example 1 a) Obtaining the catalyst The catalyst is prepared by tempering for six hours a magnetite at 150 ° C under nitrogen. The magnetite used has the following composition: 72% by weight of Fe, 0.07% by weight of Al, 0.03% by weight of Ca, 0.04% by weight of Mg, 0.11% by weight of Si , 0.01% by weight of Ti, the rest is oxygen. The sum of the promoters of group b) amounts to 0.19% by weight, the sums of the promoters of group c), calculated as oxides, amounts to 0.11% by weight.

The molten block is comminuted in a jaw crusher and a fraction with a particle size of 3 to 6 mm is sieved off. The oxidic catalyst is reduced for 72 hours in the stream of H2 / N2 at 450 ° C. After cooling under nitrogen at room temperature, the Fe catalyst is passivated with a stream of N2 / air (24 h with 1% of air in nitrogen), taking care that the temperature in the catalyst bed does not exceed 450C. b) Partial hydrogenation of DNA in ACN A tubular reactor (length 180 cm, d-30 mm) is filled with 740 ml (1819 <g) of the catalyst mass obtained according to (a) and reduced in a stream of hydrogen (500 Nl / h) , increasing the temperature within 24 h from 30 ° C to 340 ° C and maintaining the same for 72 h at 340 ° C.

After reducing the temperature in the reactor to 250 bar, a mixture is introduced from 400 ml / h of DNA, prepared from 1,3-butadiene and hydrocyanic acid (HCN) with a phosphorus content of 4 ppm. weight, 660 ml / h of ammonia and 500 Nl / h of hydrogen.

After a period of 2000 h at a reaction temperature of 120 ° C, given a constant conversion throughout the period and given a constant total selectivity (ACN + HMD) of 99%, the selectivide of ACN has only decreased insignificantly by 50% to 48%.

The DCH content in the hydrogenation discharge amounts to 2000 ppm by weight, with respect to HMD.

The content of AMCPA in the hydrogenation discharge amounts to 50 ppm by weight, with respect to HMD.

Comparative example a) Obtaining catalyst By tempering a mixture with part of magnetite, potassium carbonate,? 103, calcium carbonate, crushing of the hardened melt and sieving according to A.B. Stiles, T.A. Koch, Catalyst Manufacture (1995) p. 167/68 an oxidic mass of the following composition is obtained: 1.1% by weight of K20, 3.0% by weight of A1203, 2.3% by weight of CaO, 0.11% by weight of Si, 0 , 01% by weight of Ti, the rest are iron ósidos.

Subsequently, this mass is reduced for 72 hours in the N2 / H2 stream at 450 ° C, passivated at room temperature with a mixture of N / air (24 h with 1% of air in nitrogen), not exceeding the temperature in the catalyst bed 45 ° C, and washed for 7 days with water.

The catalyst mass has the following composition: 1.2% by weight of Al, 0.74% by weight of Ca, 0.02% by weight of K, 0.11% by weight of Si, 0.01% by weight weight of Ti, Fe / Fe oxide residue. The sum of the promoters of group b) amounts to 1.32% by weight, the sum of the group c), calculated as oxideds, amounts to 1.06% in weight.

Partial hydrogenation of DNA in ACN A tubular reactor (length 180 cm, d = 30 mm) is filled with 740 ml (1819 g) of the catalyst mass obtained according to a) and reduced without pressure in the hydrogen stream (500 Nl / h), increasing the temperature within 24 h from 30 ° C to 340 ° C and maintaining the same, then, for 72 h at 340 ° C.

After reducing the temperature, a mixture of 400 ml / h of DNA, obtained from 1,3-butadiene and hydrocyanic acid (HCN) and containing 4 ppm by weight of phosphorus, is introduced into the reactor at 250 bar. 660 ml / h of ammonia and 500 Nl / h of hydrogen.

After a period of 2000 h at a reaction temperature of 120 ° C, given a constant conversion throughout the period and a constant total selectivity (ACN + HMD) of 99%, the selectivity of ACN goes down from 40% to 25% .

The DCH content in the hydrogenation discharge amounts to 4000 ppm by weight, with respect to HMD.

The AMCPA content in the hydrogenation discharge amounts to 150 ppm by weight, with respect to HMD. fifteen twenty

Claims (9)

1. CLAIMS A process for the preparation of alpha, omega-a aliphatic inonitriles by partial hydrogenation of alpha, omega-dinitriles aliphatic in the presence of a catalyst that (a) contains iron or an iron-based compound or mixtures thereof and (b) contains from 0.01 to 5% by weight, based on (a), of a promoter based on 2, 3, 4 or 5 selected elements within the group consisting of aluminum, silicon, zirconium, titanium and vanadium and (c) ) from 0 to 0.5% by weight, based on (a), of a compound based on an alkali metal or an alkaline earth metal, where the alpha, omega-dinitrile employed contains 1.0 ppm by weight or more of phosphorus.
2. The process according to claim 1, wherein the catalyst can be obtained by reduction and, if required, the subsequent passivation of a magnetite and has a BET surface area comprised between 3 and 10 m2 / g, a total pore volume of 0.05 to 0.2 ml / g, an average pore diameter of 0.03 to 0.1 μm and a volumetric pore fraction of 50 to 70% within a range of 0.01 to 0.1 μm.
3. A process according to claim 1 or claim 2, wherein an iron oxide or a mixture of iron oxides is used as the iron-based compound.
4. 4. A process according to any of claims 1 to 3, wherein a promoter based on aluminum, silicon and vanadium is employed.
5. 5. A process according to any of claims 1 to 4, wherein the catalyst is a supported catalyst.
6. 6. A process according to any of claims 1 to 5, wherein the catalyst is an unsupported catalyst.
7. 7. A process according to any of claims 1 to 6, wherein the dinitrile used is adiponitrile, obtaining β-aminocapronitrile.
8. 8. A process according to any of claims 1 to 6 for the simultaneous preparation of 6-aminocapronitrile and examethylenediamine starting from adiponitrile by (1) the partial hydrogenation of adiponitrile in the presence of a catalyst, obtaining a mixture containing 6 -aminocapronitrile, hexamethylenediamine and adiponitrile, and (2) the isolation of 6-aminocapronitrile and hexamethylenediamine from the mixture.
9. 9. A process according to any of claims 1 to 8, wherein the hydrogenation is carried out in suspension. . A process according to any of claims 1 to 8, wherein the hydrogenation is carried out in a fixed bed reactor. . A process according to any of claims 1 to 10, wherein the alpha, omega-dinitrile employed was obtained by hydrocyanation - in the presence of phosphorus-containing catalysts - of an alpha, omega-diene having two less carbon atoms.