MXPA00008228A - Iron-based catalyst for hydrogenating alpha-, omega-dinitriles - Google Patents

Abstract

The invention relates to a substance which is suitable for use as a catalyst, containing 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, c) 0 to 0.3 wt.%in relation to a) of a compound based on an alkaline and/or alkaline earth metal and d) 0.001 to 1 wt.%in relation to a) of manganese. The inventive substances can be used as catalysts for the hydrogenation of alpha-, omega-dinitriles.

Description

HYDROGENATION CATALYST Description The present invention relates to an appropriate mass as catalyst, 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, (c) from 0 to 1% by weight, with respect to (a), of a compound based on an alkali metal and / or an alkaline earth metal, as well as (d) from 0.001 to 0.3% by weight, with respect to (a), of manganese.

In addition, the invention relates to a process for the hydrogenation of alpha, omega dinitriles, in the presence of such masses as a catalyst, and to the use of such masses as a catalyst in the hydrogenation of alpha-omega dinitriles.

It is generally known, for example, from Weissermel / Arpe, Industrielle Organische Chemie, Verlag Chemie, third edition, 1988, page 266, and WO-A-96/20166, to hydrogenate adipodium in the presence of ammonia under high pressure conditions, in presence of catalysts containing mostly iron, giving 6-aminocapronitrile and / or hexamethylenediamine, both being important intermediate products for the preparation of polyamides, such as nylon 6 and nylon 6.6.

Important characteristics for optimal iron catalysts are a high mechanical strength, a long catalyst life, a high space-time yield in the value products: alpha, agam-aminonitrile and / or alpha, ormega-diamine, given a conversion complete of the alpha, oomega-dinitrilo and contents as small as possible in undesired side products.

These undesired by-products are formed, depending on the catalyst, in different amounts and are only difficult and complicated to separate from the formed product: amino-nitrile and / or diamine.

Thus they are formed, for example, in the hydrogenation of adipodini-trile giving hexamethylenediamine, different amounts of, for example, tetrahydroazepine (TECA), l-amino-2-cyanocyclopentene (ICCP), 2-aminomethylcyclopentylamine (AMCPA), 1, 2 -diaminoci-clohexane (DCH) and bishexamethylenetriamine (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 investment and energy costs.

From US-A-4,282,381, column 2, table 1, it is known that, in the hydrogenation of adiponitrile in hexamethylenediamine in the presence of iron catalysts, on average, 2,400 to 4,000 ppm are formed as by-products, among others. 1,2-diaminocyclohexane, 100 to 300 ppm of 2-aminomethylcyclopentilamine, 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. From example 2 it is known 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 labradorite! ta-hematia (Fe03) by reduction with hydrogen, 98.05% hexamethylenediamine with a content of 3500 ppm of 1,2-diaminocyclohexane.

The object of the present invention is therefore to provide a process for the hydrogenation of alpha, omega-dinitriles (I) in alpha, omega-aminonitriles (II) and / or alpha, omega-diamines (III), in the presence of the catalyst, as well as catalysts, which do not have the above-mentioned drawbacks and which allow hydrogen to be hydrogenated in a simple and economical manner alpha, oem-dinitriles with high selectivity, the catalyst having a long duration.

The masses defined above were found, the procedure defined above, as well as the use defined above.

The masses according to the invention preferably have a BET surface area of 3 to 20 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 pore volume ratio in the region of 0.01 to 0.1 μm from 50 to 70%.

The% by weight indicated in (b) and (d) 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 varies from 1.25: 1 to 1.45: 1, preferably, 1.3: 1 to 1.4: 1, most preferably it will be 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 those, in which the component (b) contains from 0.001 to 0.3% by weight of, preferably 0.01 to 0.2% by weight of, especially 0.01 to 0.1% by weight, 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 compositions according to the invention contain 0.001 to 1% by weight, preferably 0.001 to 0.3% by weight, in particular 0.01 to 0.2% by weight, of manganese.

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 the components (a) are precipitated, if desired, together with precursors of the components (b), (d) 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), (d) and, optionally (c), the individual components can be added simultaneously or successively, or by spraying the components ( a), (b), (d) and, optionally (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 components (b) and (d), 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 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 the 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 gas mixture that confines hydrogen and an inert gas, such as nitrogen, for example. 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, the 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 user temperatures, of from 20 to 80, preferably by evaporation, can be avoided. 25 to 35 ° C by means of 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 dini-trile of succinic acid, glutaric acid dinitrile, diniphenyl of adipic acid ( "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 phosphorus of an alpha, or ega-diene with two less carbon atoms, such as, for example, adiponitrile by the addition of nitric acid to butadiene, or -pentenenitrile in the presence of compounds of (0) containing nickel and triarylphosphites.

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 long catalyst permancy times achieved in the catalyst can be further increased. process according to the invention and by the use according to the invention.

To reduce the weight ratio of the phosphorus-containing compound in the mixture, different known methods 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 bar, 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 adipodinitrile .

According to the process of the invention, the dinitriles described above I can be hydrogenated, preferably in the presence of a solvent, using a catalyst, to give the alpha-, omega-aminonitriles of the general formula II NC- (CH2) n-CH2-NH2 II having n the meanings indicated above. Very preferred aminonitriles II are those, in which n has the value 2, 3, 4, 5 or 6, especially 4, namely, 4-amino-butanoic acid nitrile, 1,5-aminopentanoic acid nitrile, acid nitrile 1,6-aminohexanoic ("6-aminocapronitrile"), 1,7-aminoheptanoic acid nitrile and 1,8-aminooctanoic acid nitrile, 6-aminocapronitrile being especially preferred.

When the reaction is carried out in suspension, then temperatures are usually selected in the region of 40 to 150 ° C, preferably 50 to 100 ° C, very preferably 60 to 90 ° 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, substantially, on the performance, selectivity desired, given a complete conversion; normally, the retention time of such maenra is chosen, which, given a complete conversion, reaches a maximum yield, for example, from 50 to 275 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 trimethylamin, 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 discontinuous or continuous form in a fixed-bed reactor by means of a run-off or exhaustion method in a straight passage or with recycling of the product, generally selecting a temperature in the region of 20 to 150 °. C, preferably from 15-30 to 90 ° C and, normally, a pressure in the region of 2 to 40 MPa, preferably from 3 to 30 MPa. Preferably, hydrogenation is carried out in the presence of a solvent, preferably ammonia, amines, diamines and triamine 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 content is selected (ammonia nest 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 0.3, is selected here 1.0 kg of adiponitrile / 1 x h.The degree of conversion can also be specifically regulated here, changing the retention time.

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

The ratio between the aminonitriles (II) and the diamines (III) can be regulated by selecting a specific temperature and catalyst load.

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

The separation of 6-aminocapronitrile, hexamethylenediamine and a substantially adipodinitrile-containing part of the mze-cla can be carried out in a manner known per se, preferably by distillation, for example, according to DE-A-19 500 222 or the patent application German 19 548 289.1, simultaneously or successively.

The process of the invention makes it possible to hydrogenate the dinitriles I described above, preferably in the presence of a solvent, using a catalyst, giving the alpha-, diametals of the general formula III H2N-CH2- (CH2) n-CH2-NH2 III having n the meanings indicated above. Especially preferred diamines III 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-diaminoheptane and 1,8-diaminooctane, especially 1,6-diaminohexane.

When the suspension reaction is carried out, a temperature is generally chosen in the region of 60 to 200 ° C, preferably 60 to 180 ° C, very preferably 70 to 130 ° C. The pressure is chosen in the region from 2 to 30 Mpa, preferably from 3 to 30 Mpa, very preferably from 4 to 20 Mpa. The retention times depend, substantially, on the desired yield and selectivity, given a complete conversion; normally, the retention time is chosen such that a maximum yield is reached, for example, in the region of 50 to 300 min, preferably 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 here. 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.

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-diaminocyclohexan, tetrahydroazepine and bishexanmethylene trlamine.

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

Alpha, omega-aminonitriles and alpha-, omega-diamines are important starting materials for obtaining nylon 6. 6 and / or nylon 6.

In the examples they mean: DNA = adiponitrile ACN = 6-aminocapronitrile HMD = hexamethylenediamine DCH = 1,2-diaminocyclohexane AMCPA = 2-aminomethylcyclopentylamine BHMTA = bis-hexamethylenetriamine ICCP = l-amino-2-cyanocylopentene THA = tetrahydroazepine HMI = hexamethyleneimine The analysis values summarized in the 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, 0.06% by weight of Al, 0.03% by weight of Ca, 0.04% by weight of Mg, 0.10% 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 hydrogen / nitrogen at 450 ° C. After cooling under nitrogen at room temperature, the Fe catalyst is passivated in a nitrogen / air stream (24 h with 1% by volume of air in nitrogen) at a temperature not above 45 ° C. b Hydrogenation of DNA giving HMD and / or ACN Three tubular reactors arranged 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) (1.5 to 3 mm gravel) and • then it is reduced without pressure in the hydrogen current (200 l / 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 or 148 ml / h of DNA (catalyst loading: 0.5 or 1.0 kg of DNA / 1 cat. Xh), 365 ml / h of NH3 and 200 Nl / h of H2. After a running time of 7000 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 catalyst load (table 1): r fifteen twenty Hexamethylenediamine by hydrogenation of adiponitrile 00 1) Selectivity in ACN [%]

Claims (1)

1. CLAIMS . A process for the hydrogenation of alpha, omega-dinitriles in the presence of a catalyst, which consists of using a catalyst containing a material consisting of: (a) iron or an iron-based compound 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. (c) from 0 to 0.3% by weight, based on (a) of an alkali metal and / or alkaline earth metal compound, and also (d) from 0.001 to 1% by weight, based on (a) of manganese. . The process as claimed in claim 1, wherein the material has a BET surface area from 3 to 20 m2 / g, a total pore volume from 0.05 to 0.2 ml / g, an average pore diameter from 0.03 to 0.1 μ and a fraction of the pore volume from 0.01 to 0.1 μ in the range from 50 to 70%. . The process as claimed in claim 1 or 2, wherein the material 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 (b) 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 hydrogenation is carried out in a fixed bed reactor. The process as claimed in any of claims 1 to 6, wherein the catalyst is a catalyst without support. The process as claimed in any of claims 1 to 1, wherein alpha, omega-dinitrile is hydrogenated to an alpha, omega-diamine. The process as claimed in claim 8, wherein the alpha, omega-dinitrile used is adiponitrile to obtain hexamethylenediamine. The process as claimed in any of claims 1 to 7, wherein the alpha, omega-dinitrile is hydrogenated to an alpha, omega-aminonitrile. The process as claimed in claim 10, e? where the alpha, omega-dinitrile used is adiponitrile to obtain β-aminocapronitrile. 12. The process as claimed in any of claims 1 to 11, wherein the alpha, omega-dinitrile used was obtained by hydrocyanation in the presence of phosphorus catalysts of an alpha, omega-diene having two carbon atoms less. 13. The process as claimed in claim 12, wherein the weight fraction of the phosphorus compound in alpha, omega-dinitrile is reduced. The process, as claimed in claim 12, wherein the weight fraction of the phosphorus compound, calculated as phosphorus, is less than 5 ppm, based on alpha, omega-dinitrile, after the reduction in the concentration of phosphorus compounds. 15. The process as claimed in claim 12, wherein the fraction of the phosphorus compound, calculated as phosphorus, is less than 1 ppm, based on alpha, omega-dinitrile, after the reduction in the concentration of the phosphorus compounds. 16. The use of materials as set forth in any of claims 1 to 5 as catalysts in the hydrogenation of alpha, omega-dinitriles. 17. The material as set forth in any of claims 1 to 5, which can be obtained by reduction with or without subsequent passivation of a magnetite. The material as set forth in any of claims 1 to 5, which can be obtained by precipitating the precursors of the components (a), (b), (d) and optionally (c) in the presence or absence of support materials. The material as set forth in any of claims 1 to 5, which can be obtained by impregnating a support with a solution of the components (a), (b), (d) and optionally (c). The material as set forth in any of claims 1 to 5, which can be obtained by spraying components (a), (b), (d) and optionally (c) onto a support.