MXPA00008159A - Method for producing aliphatic alpha-, omega-diamines - Google Patents

Abstract

The invention relates to a method for producing aliphatic alpha-, omega-diamines by hydrogenating aliphatic alpha-, omega-dinitriles in the presence of a catalyst, characterised in that the catalyst used for the hydrogenation contains a) iron or a compound based on iron or mixtures thereof, b) 0. 001 to 0.3 wt.%in relation to a) of a promoter based on 2, 3, 4 or 5 elements from the following group:aluminium, silicon, zirconium, titanium and vanadium and c) 0 to 0.3 wt.%in relation to a) of a compound based on an alkaline and/or alkaline earth metal.

Description

PROCEDURE FOR OBTAINING ALPHA, OMEGA-ALIPHATIC DIAMINES Description The present invention relates to a process for obtaining aliphatic alpha, ormega-diamines by hydrogenation of alpha, aliphatic dinitriles in the presence of a catalyst, which process is characterized in that a catalyst is used for hydrogenation, which contains (a) iron or an iron-based compound or mixtures thereof, (b) from 0.001 to 0.3% 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, vanadium, and as (c) from 0 to 0.3% by weight, with respect to (a), of a compound based on an alkali metal and / or an alkaline earth metal.

Furthermore, the invention relates to the use of masses, which contain the components (a), (b) and (c) as catalysts in the preparation of alpha, ormega-diamines by hydrogenation of alpha-, omega-dinitriles.

From Eissermel / Arpe, Industrielle Organische Chemie, Verlag Chemie, third edition, 1988, page 266, it is known to hydrogenate adipodinitrile in the presence of ammonia under high pressure conditions, in the presence of iron catalysts, giving hexamethylenediamine, an important intermediate product for obtaining nylon 6.6.

Important characteristics for optimal iron catalysts are a high mechanical resistance, a long catalyst life, a high space-time yield in hexamethylenediamine, given a complete conversion of adipodinityl and 6-aminocapronitrile, an alteration in hexamethylenediamine with a very low content possible in unwanted by-products.

These undesired by-products are formed, depending on the catalyst, in different amounts and are only difficult and complicated to separate from the diamine formed as a valuable product.

Thus they are formed, for example, in the hydrogenation of adipodini-trile giving hexamene-1-diamine, different amounts of, for example, 6-aminocapronitrile (ACN), tetrahydroazepine (THA), l-amino-2-cyanocyclopentene (ICCP), 2- aminomethylcyclopentyl-mine (AMCPA), 1,2-diaminocyclohexane (DCH) and bis-hexamethylene-triamine (BHMTA). From US-A 3 696 153 it is known that AMCPA and DCH are very difficult to separate from hexamethylenediamine. Especially high amounts of AMCPA, DCH and THA result in high distillation costs, which translate into considerably high research and energy costs.

From US-A-.282,381, column 2, table 1, it is known that in the hydrogenation of adiponitrile in hexamethylenediamine in the presence of iron catalysts, an average of 2,400 to 4,000 ppm of 1, 2 are formed as by-products, among others. -diaminocyclohexane, 100 to 300 ppm of 2-aminomethyl-clopentilamine, 200 to 900 ppm of tetrahydroazepine and 2000 to 5000 ppm of 6-aminocapronitrile.

From DE-A-2 429 293, Example 1, it is known that, in the hydrogenation of adiponitrile, the quantity of ammonia at 93 to 98 ° C (inlet temperature in the reactor) is obtained in the presence of five times. or 94 to 104 ° C (exit temperature), in the presence of an iron catalyst equipped with aluminum oxide, silicon dioxide, calcium oxide and vanadium pentoxide, prepared from magentite by reduction with hydrogen, 98, 22% hexamethylenediamine with a content of 1.2 diaminicyclohexane of 1900 ppm. It is known from Example 2 that in the hydrogenation of adiponitrile, in the presence of five times the weight of ammonia, it is obtained at 93 to 98 ° C (inlet temperature in the reactor) or 94 to 104 ° C (temperature of exit, in the presence of an iron catalyst equipped with aluminum oxide, silicon dioxide and calcium oxide, prepared from a labradori a-hematia mineral (Fe20) by reduction with hydrogen, 98.05% of hexamethylenediamine with a content of 3500 ppm of 1.2 diaminocyclohexane.

Therefore, the present invention has for its object to provide a process for the hydrogenation of alpha, omega-dinyroles (I) in alpha, ormega-diamines, in the presence of a catalyst, which does not have the drawbacks indicated above and which makes it possible to obtain in a simple and economical way alpha, diameters with high selectivity, the catalyst having a long duration.

The procedure defined above was found, as well as the use defined above.

The catalysts in the process of the invention and the use according to the invention preferably have a BET surface of 3 to 20 m2 / g, a total pore volume of 0.05 to 0.2 ml / g, a pore diameter medium from 0.03 to 0.1 μm and a volume ratio of pores in the region of 0.01 to 0.1 μm from 50 to 70%.

The% by weight indicated in (b) refer to the elements, the% indicated in (c) to the oxides of the alkali and alkaline earth metals. These indications refer to component (a).

Preferred catalyst precursors are those, in which the component (a) comprises from 90 to 100% by weight, preferably from 92 to 99% by weight, based on (a), of iron oxides, iron hydroxides , iron oxyhydroxides or their mixtures. Preferably, iron oxides, iron hydroxides or synthesized or natural iron hydroxides, such as limonite, hematite, preferably magnetite, are used, which can ideally be described by the formula Fe304. The atomic ratio between oxygen and iron preferably ranges from 1.25: 1 to 1.45: 1, preferably 1.3: 1 to 1.4: 1, most preferably to 1.33: 1, viz. , pure magnetite.

When the magnetite is prepared synthetically, then it can be split from very pure metallic iron or very pure iron (II) and / or iron (III) compounds, to which the endowment elements are added in the form of compounds appropriate.

Preferred catalyst precursors are, in addition, those in which component (b) contains from 0.001 to 0.3% by weight, preferably 0.01 to 0.2% by weight, especially 0.01 to 0.1% by weight of a promoter based on 2, 3, 4 or 5, preferably 3, 4 or 5 elements selected from the group comprising aluminum, zirconium, silicon, titanium or vanadium, especially the combination of aluminum, silicon and titanium.

Preferred catalyst precursors are, in addition, those in which the component (c) contains from 0 to 0.3% by weight, preferably 0.01 to 0.2% by weight, most preferably 0.01 to 0.1 % by weight of a compound based on an alkali metal or alkaline earth metal selected from the group comprising lithium, sodium, potassium, rubidium, cesium, magnesium and calcium, preferably calcium and / or magnesium.

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

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

As precursors of the components (a), generally well-soluble salts of iron are suitable, such as nitrates, chlorides, acetates, formates and sulphates, preferably nitrates.

As precursors of the components (b), generally well-soluble salts or complex salts of the metals and semimetals mentioned above are suitable, such as nitrates, chlorides, acetates, formates and sulfates, preferably nitrates.

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

The precipitation is usually carried out from aqueous solutions, adding precipitation reagents, varying the pH value or changing the temperature.

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

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

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

According to DE 24 29 293, page 7, lines 1 to 12, it can be advantageous to add ammonia to the hydrogen used for the activation.

Advantageously, activation of the catalyst is carried out directly in the synthesis reactor, since in this way the intermediate step normally required, namely the passivation of the surface at the usual temperatures of 20 to 80, preferably 25 to 35, can be avoided. ° C by oxygen-nitrogen mixtures, such as, for example, air. Activation of passivated catalysts is then carried out in the synthesis reactor at a temperature of 180 to 500, preferably 200 to 350 ° C in an atmosphere containing hydrogen.

The catalysts can be used as fixed bed catalysts in a runoff or depletion method.

The aliphatic alpha, omega-dinitriles of the general formula I are used as starting substances in the process of the invention, NC- (CH2) n-CN I wherein n is an integer from 1 to 10, especially 2, 3, 4, 5 and 6. The dinitryl of succinic acid, glutaric acid dinitrile, adipic acid dinitrile ( "adipodinitrile"), pimelic acid dinitrile and suberic acid dinitrile ("suberonitrile"), with adipodinitrile being especially preferred.

Alpha, methene dinitriles obtained by hydrocyanuration are preferably used in the presence of catalysts containing one alpha phosphorus, two-membered diene with two less carbon atoms, such as, for example, adiponitrile by the addition of nitric acid to butadiene, or pentenonitrile in the presence of (O) compounds containing nickel and triaryl phosphites.

Such alpha, omega-dinitriles may contain traces of phosphorus-containing compounds, for example, 1 to 50 ppm, calculated as phosphorus, with respect to alpha, omega-dinitrile. When these phosphorus compounds are totally or partially removed, whereby by weight ratios of phosphorus-containing compounds of less than 5 ppm, preferably less than 1 ppm, are obtained, then the high catalyst durations achieved in the process can be further increased. the invention and by use according to the invention.

To reduce the proportion by weight of the compound containing phosphorus in the mixture, different known processes can be applied, such as precipitation, preferably extraction, treatment with a base, such as, for example, sodium hydroxide solution or potassium hydroxide solution, adsorption or chemical absorption. , especially in a metal, such as iron or, very preferably, distillation. Also very preferred is the treatment of dinitrile with alkali metal or alkaline earth metal base bases, lanthanides and groups III a, II b and III b of the periodic system, such as calcium oxide, for example.

The distillation can be carried out, advantageously, at pressures of 1 to 100 mbar, preferably 10 to 200 mbar, obtaining adipodinitrile in most cases as a product of heads, since, generally, the compounds containing phosphorus are less volatile than the adiponitrile .

According to the process of the invention, the dinitriles I described above are hydrogenated, preferably in the presence of a solvent, using a catalyst, giving alpha, diametal diamines of the general formula II NC- (CH2) n-CH2-NH2 II having n the meanings indicated above. Very preferred diamines II are those, in which n has the value 2, 3, 4, 5 or 6, especially 4, namely 4-diaminobutane, 1,5-diaminopentane, 1,6-diaminohexane. { "hexamethylenediamine"), 1,7-diami-noheptane and 1,8-diaminoocatane, with 1,6-diaminohexane being especially preferred.

When the reaction is carried out in suspension, then temperatures are usually selected in the region of 60 to 200 ° C, preferably 60 to 180 ° C, very preferably 70 to 130 ° C. Generally, a pressure is chosen in the region of 2 to 30 MPa, preferably 3 to 30 MPa, most preferably 4 to 9 MPa. The retention times depend, essentially, on the performance, selectivity desired, given a complete conversion; normally, the retention time is chosen in such a way that, given a complete conversion, a maximum yield is reached, for example, from 50 to 300 min, preferably from 70 to 200 min.

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

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

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

It is also possible to carry out the hydrogenation in batch or continuous form in a fixed bed reactor by a runoff or depletion method, in a straight passage or with recycling of the product, generally selecting a temperature in the region of 70 to 200 ° C. , preferably, from 80 to 150 ° C and, normally, a pressure in the region of 2 to 40 MPa, preferably, from 3 to 30 MPa. Preferably, the hydrogenation is carried out in the presence of a solvent, preferably ammonia, amines, diamines and triamines with 1 to 6 carbon atoms, such as trimethylamine, triethylamine, tripropylamine and tributylamine, or alcohols, preferably methanol and ethanol, most preferably ammonia. . In a preferred embodiment, the ammonia content is selected in the region of 1 to 10 g, preferably 2 to 6 g per gram of adiponitrile. Preferably, a catalyst loading of 0.1 to 2.0 kg, preferably 0.3 to 1.5 kg of adiponitrile / 1 x h is selected. Also here you can specifically regulate the degree of conversion, changing the retention time.

The hydrogenation can be carried out in a reactor suitable for this purpose.

It is known that in the hydrogenation of alpha, ormethyrimethyls in alpha, ormega-diamines can be formed as by-products alpha, ormega-aminonitriles. The process of the invention makes it possible to reach contents in these aminonitriles of less than 2000 ppm, preferably less than 1000 ppm, especially less than 500 ppm, with respect to the diamine.

In the hydrogenation of adiponitrile such as alpha, omega-dinitryl, a mixture is obtained which, in addition to the solvent, contains, predominantly, hexamethylenediamine, which may contain as impurities, in particular 6-aminocaprony-trile, hexamethyleneimine, 2-aminomethylcyclopentylamine, 1.2-diaminocyclohexane, tetrahydroazepine and bishexanmethylene triamine.

The purification of the crude hexamethylenediamine after removal of the solvent is usually carried out preferably by distillation.

Alpha-, omega-diamines are important starting materials for obtaining nylon 6.6.

In the examples they mean: DNA = adiponitrile ACN = 6-aminocapronitrile HMD = hexamethylenediamine DCH = 1,2-diamidocyclohexane AMCPA = 2-aminomethylcyclopentylamine BHMTA = bis-hexamethylenetriamine ICCP = l-amino-2-cyanocylopentene THA = tetrahydroazepine HMI = hexamethyleneimine The analysis values summarized in Table were obtained by means of quantitative gas chromatography.

Example 1 a) Obtaining the catalyst The catalyst is prepared by tempering six hours of a magnetite mineral at 1500 ° 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, 0.13% by weight of Mn, the rest is oxygen.

The cooled molten block is shredded in a jaw crusher and a fraction of a particle size of 1.5 to 3 mm is sifted. The oxidic catalyst is reduced for 72 hours in a stream of H / N at 450 ° C. After cooling under nitrogen at room temperature, the Fe catalyst is passivated in a stream of N2 / air (24 h with 1% by volume of air in nitrogen) at a temperature not above 45 ° C. hydrogenation of DNA giving HMD Three tubular reactors connected in series (total length: 4.5 m, d = 6 mm) are filled with 142 ml (240 g) of the catalyst prepared according to example 1 a) (gravel 1.5 to 3 mm) and then it is reduced without pressure in the hydrogen current (200 1 / h). For which the temperature rises within 24 hours from 70 ° C to 340 ° C and then it is maintained for 72 hours at 340 ° C. After reducing the temperature in the reactor to 250 bar, a mixture is introduced from 74 ml / h of DNA (catalyst loading: 0.5 kg of DNA / 1 cat. Xh), 365 ml / h of NH3 and 200 Nl / h of H2. After a running time of 6000 hours no decrease in catalyst activity is observed. Under the conditions indicated in table 1, the following results are obtained as a function of the temperature and loading of the catalyst (table 1): Hexamethylenediamine by hydrogenation of adiponitrile cp

Claims (1)

1. CLAIMS A process for preparing alpha, aliphatic omega-diamines by hydrogenation of alpha, aliphatic omega-dinitriles in the presence of a catalyst which consists of using a hydrogenation catalyst containing: iron or a compound based on iron (a), or mixtures thereof, (b) from 0.001 to 0.3% by weight, based on (a) of a promoter based on 2, 3, 4 or 5 elements selected from the group consisting of: aluminum, silicon, zirconium, titanium and vanadium, and also (C) 0 to 0.3% by weight, based on (a), of a compound based on an alkali metal and / or alkaline, alpha, omega-day ina aliphatic contains less than 20 ppm of alpha, omega- aminonitrile based on diamine. The process as claimed in claim 1, wherein the catalyst has a BET surface area from 3 to 20 m2 / g, a total pore volume from 0. 05 up to 0.2 ml / g, an average pore diameter from 0. 03 to 0.1 μ and a fraction of the pore volume of 0.01-0.1 μ in the range from 50 to 70%. The process as claimed in claim 1 or 2, wherein the catalyst can be obtained by reduction with or without subsequent passivation of a magnetite. The process as claimed in any of claims 1 to 3, wherein a promoter based on aluminum, silicon and titanium is used. The process as claimed in any of claims 1 to 4, wherein a promoter (c) based on magnesium and / or calcium is used. The process as claimed in any of claims 1 to 5, wherein the catalyst is a catalyst without support. The process as claimed in any of claims 1 to 6, wherein the hydrogenation is carried out in a fixed bed reactor. The process as claimed in any of claims 1 to 7, wherein the dinitrile used is adiponitrile to obtain hexamethylenediamine. The process as claimed in any of claims 1 to 8, wherein less than 2000 ppm of alpha, aliphatic omega-diamine is obtained from a corresponding aliphatic alpha, omega-aminonitrile as a by-product. The process as claimed in any of claims 1 to 9, wherein the alpha, omega-dinitrile used was obtained by hydrocyanation it in the presence of catalysts match an alpha, omega-diene having two carbon atoms fewer. The process as claimed in claim 10, wherein the weight fraction of the phosphorus compound in alpha, omega-dinitrile is reduced. The process as claimed in claim 11, wherein the weight fraction of a phosphorus compound, calculated as phosphorus, is less than 5 ppm, based on alpha, omega-dinitrile, after the reduction in the concentration of the phosphorus compounds. The process as claimed in claim 11 or 12, wherein the weight fraction of a phosphorus compound, calculated as phosphorus, is less than 1 ppm, based on alpha, omega-dinitrile, after reduction in the concentration of phosphorus compounds.