MXPA99002080A - Catalysts suitable for preparing aliphatic alpha-, omega-aminonitriles by partial hydrogenation of aliphatic dinitriles - Google Patents

Abstract

The invention concerns catalysts suitable for preparing aliphatic alpha-, omega-aminonitriles by partial hydrogenation of aliphatic dinitriles, containing:(a) metallic cobalt, a cobalt compound or their mixtures, the metallic cobalt portion being between 20 and 100 wt%relative to (a);(b) between 10 and 70 wt%, relative to (a), of metallic iron, iron oxide, a further iron compound or their mixtures, the iron oxide portion being between 20 and 100 wt%relative to (b);and (c) between 0 and 1 wt%, relative to (a), of a compound based on an alkali metal, alkaline earth metal or zinc.

Description

CATALYSTS ADEQUATE FOR THE PREPARATION OF ALPHA-, OMEGA- AMINONIT ILOS ALIPHATIC THROUGH PARTIAL HYDROGENADION OF ALIPHATIC DINITPILLS The present invention relates to catalysts suitable for the preparation of alpha, aliphatic amega-aminonitriles by the partial hydrogenation of aliphatic dinitriles. It also relates to processes for the preparation of alpha, aliphatic amega-aminanitriles by the partial hydrogenation of aliphatic dipitriles in the presence of such catalysts and the use of catalysts for the preparation of alpha, or aliphatic ega-aminonitriles by the partial hydrogenation of dinitriles aliphatic WO 92/21650 discloses the partial hydrogenation of adipanitrile in 6-amipocapronitrile in the presence of a Raney nickel catalyst and ammonia as a solvent with a yield of 607. at a conversion of 70X. The hexameti lepdia ina is formed as a by-product with a yield of 9%. The disadvantage of this process is the short time in the catalyst flow. US 2,257,814 and US 2,208,598 describe in the same manner processes for the preparation of 6-aminocapronitri starting from adiponitrile using catalysts of Raney cobalt and iron, nickel and cobalt in various supports. The disadvantages of these processes are selectivities of 50-60 / C which are too low for their. industrial use. According to the process of WO 93/16034, the yield of inocapronitri can be increased by hydrogenation of adiponitrile in the presence of Raney nickel, a base with, for example, sodium hydroxide, potassium hydroxide, hydroxide. lithium or ammonium hydroxide and a transition metal complex including, for example, iron, cobalt, chromium or tungsten as the transition metal, and a solvent. The reaction within the range of 45 to 60% yields, according to this document, quantitative aminocapronitrile yields The disadvantage of this process is the need to recover the normally toxic transition metal complex from the reaction mixture. EP-A 161,419 discloses the partial hydrogenation of adiponitrile using a rhodium catalyst in a magnesium oxide support, a selectivity of 94"/. with a conversion of 70i. The disadvantage is the complicated separation of the Rh / Mgo catalysts (see J. Cat. 112 (1988), 145-156). DE-A 4,235,466 describes the fixed bed hydrogenation of adiponitrile in 6-aminocaprony trile in unsupported iron sponge catalysts prepared from iron ore by means of a special method and subsequently doped with cobalt, titanium, manganese , chromium, mol bdena, ruthenium or iridium. Due to their small surface area (0.8 m2 / q), these catalysts generally have a useful activity only at high pressures and high temperatures. A further disadvantage of this process is the rapid loss of activity: the conversion decreased by 5"/. In 24 hours in Example 7 despite the reduction in flow velocities of adiponitrile and hydrogen, which usually causes an increase in The DE-A 848,654 describes the hydrogenation in fixed continuous bed of adiponitrile in palladium or silica gel and in metals of the eighth group of the Periodic Table, these metals are preferably used in the form of spinels. It is an object of the present invention to provide suitable catalysts for the preparation of aliphatic alpha, omega-aminonitriles by the partial hydrogenation of aliphatic dinitriles with high selectivity for alpha, omega aminopitri and in terms of the total sum of alpha, omega-aminotriles and alpha, amega-diamines, we have found that this object is achieved through suitable catalysts for the preparation of aliphatic alpha, omega-aminonitriles by partial hydrogenation of aliphatic dinitriles comprising (a) cobalt metal, a cobalt compound or a mixture thereof, the proportion of metallic cobalt based on (a) is from 20 to 1007. by weight, b) from 10 to 707. by weight, based on (a), of metallic iron, iron oxide, an additional iron compound or a mixture thereof, the proportion of iron oxide based on (b) is from 20 to 1007 by weight. The invention further provides processes for the preparation of aliphatic alpha, omega-aminonitriles by the partial hydrogenation of aliphatic dinitriles in the presence of such catalysts and for the use of the catalysts for the preparation of aliphatic alpha, amega-aminonitriles by the partial hydrogenation of dipitriles. aliphatic Preference is given to catalysts whose precursor, before activation with hydrogen or a mixture of gases comprising hydrogen and an inert gas such as nitrogen, comprises one or more cobalt compounds, calculated as cobalt (II) oxide, within of the range from 10 to 807. by weight, preferably from 20 to 707. by weight, particularly from 30 to 60% by weight. Preference is given to catalysts whose precursor, before activation with hydrogen or with a gas mixture comprising hydrogen and an inert gas with for example nitrogen, comprises one or more iron compounds, calculated as iron (III) oxide. , within the range of 20 -? 90-. by weight, preferably from 30 to 807 by weight, in particular from 40 to 70% by weight. The catalysts which can be used according to the present invention can be supported or unsupported catalysts. Examples of suitable supported materials include porous oxides such as for example aluminum oxide, silicon dioxide, aluminosilicate, lanthanum oxide, titanium dioxide, zirconium dioxide, magnesium oxide, zinc oxide and zeolites, and also activated carbon or mixtures of the same. They are prepared habitually by the precipitation of one or more component precursors (a) component precursor gasket (b) and, if desired, with one or more precursors of the trace component (c) in the presence or absence of support materials (depending on the type of catalyst desired), if desired by processing the resulting catalyst precursor into extruded products or tablets, by drying and subsequently calcining. The supported catalysts can also be obtained generally by saturation of the support with a solution of components (a), (b) and optionally (c), in this case the individual components can be added simultaneously or in succession, or by spraying the components (a), (b) and optionally (c) on the soup in a conventional manner.

Suitable precursors for components (a) and (b) generally include readily water-soluble salts of the aforementioned metals such as, for example, nitrates, chlorides, acetates, formations and sulfates, preferably nitrates. Suitable precursors for component (c) generally include easily water-soluble salts of the alkali metals or alkaline earth metals such as lithium, sodium, potassium, rubidium, cesium, magnesium or calcium, or zinc and also mixtures thereof. same, as for example hydrides, carbonates, nitrates, chlorides, acetates, formations and sulfates, preferably carbonates and hydroxides. The precipitation is usually carried out from aqueous solutions, selectively by adding precipitation agents, changing the pH or changing the temperature. Suitable precipitating agents include, for example, ammonium carbonate or hydroxides or carbonates of the alkali metals. If alkali metal compounds are used as precipitation agents, it is advisable to release the precipitates of adhered alkali metal compounds for example by washing with water. This can be carried out directly after the removal of the precipitate from the mother liquor or after a drying and calcination step. The drying can be carried out in a conventional manner, preferably in atomization towers, in this case the precipitate is generally suspended in a liquid, preferably in water. The resulting catalyst material is usually pre-dried, generally at a temperature comprised between 8 ° and 150 ° C, preferably • * a temperature comprised between 80 and 120 ° C. Calcination is usually carried out at a temperature of 150-500 ° C, although in individual cases temperatures of up to 1000 ° C may be suitable, preferably between 200 and 450 ° C, in an air gas stream or nitrogen in a suitable apparatus such as for example tray ovens or rotary tube ovens. The powder can be processed into shaped articles such as extruded articles or tablets in a conventional manner, especially if the catalyst material is to be used in a fixed bed. Extruded products may be produced in the presence of aggregate auxiliaries such as inorganic acids, organic acids or bases such as ammonia in which case the auxiliaries may comprise cobalt or iron compounds. After extrusion, the extruded products can be dried at a temperature lower than 200 ° C and calcined at a temperature between 150 and 500 ° C, although in individual cases temperatures up to 1000 ° C can also be adequate, preferably between 200 and 450 ° C, in an air or nitrogen gas stream in a suitable apparatus such as for example tray ovens or rotary tube ovens. Tablets can be produced in the presence of added organic or inorganic auxiliaries such as stearates, graphite or talc. The catalysts can be used as fixed bed catalysts in upflow or downflow mode or as suspension catalysts. Suitable starting materials for the process of the present invention are alpha, aliphatic amega-dinitriles of the general formula I NC- (CH2) n-CN I where "n" is an integer from 1 to 10, particularly 2, 3, 4 , 5 or 6. Particularly preferred compounds I are succinonitrile, glutaronitri, adiponitrile, pimelonitrile and suberanitrile. with adiponitrile being particularly preferred. The process of the present invention partially hydrogenates the dinitriles I described above in the presence of a solvent in a catalyst to obtain alpha, omega-aminonitriles of the general formula II NC- (CH2) n-CH2-NH2 II where "n" is conformity with the above defined. Particularly preferred aminonitriles II are aminonitriles wherein "n" is 2, 3, 4, 5 or 6, especially 4, ie 4-aminobutanetrimethylamine, 5-aminepeptannitrile, 6-aminohexannitriyl ("6-aacapronitrile"), 7-aminoheptanpitrila and 8-aminooctanpitri lo, very particularly 6-aminocapronitrilo being preferred. A suspension process is usually carried out at a temperature located within a range of 20 to 150 ° C, preferably within the range of 30 to 120 ° C.; the pressure is generally chosen within the range of 2 to 30, preferably 2 10, preferably greater than 3 to 10, and especially 4 to 9, MPa. The residence times depend essentially on the desired performance, the desired selectivity and the desired conversion; the residence time is usually chosen in order to optimize the performance, for example, within the range of 50 to 275, preferably from 70 to 200, minutes in the case of an adiponitrile feed. A suspension process is preferably carried out with a solvent selected from ammonia, amines, diamipals and triamines having from 1 to 6 carbon atoms such as, for example, trimethylamine, triethylamine, tripropylamine and tributylamine. or alcohols, especially methanol and ethanol.

Ammonia being especially preferred. It is advantageous to employ a dinitrile concentration in the range of 10 to 90, preferably 30 to 80. The suspension hydroquinone may be carried out in batches or, preferably continuously, generally in the liquid phase. The partial hydrogenation is preferably carried out in batches or continuously in a fixed bed reactor in the downflow or upflow mode whereby it is usual to employ a temperature within the range of 20 to 150 ° C, preferably within the range of 30 to 120 ° C, and a pressure generally within the range of 20 to 30, preferably within the range of 3 to 20 MPa. The partial hydrogenation is preferably carried out in the presence of a solvent, preferably ammonia, amines, diamipals and triamines having from 1 to 6 carbon atoms, for example trimethylamine, triethylamine, tripropylamine and tributylamine or alcohol, preferably methanol. or ethanol, with ammonia especially preferred. In a preferred embodiment, the ammonia is employed within the range of 0.5 to 10, preferably 0.5 to 6, g per g of adiponitrile. A catalyst spatial velocity within the range of 0.1 to 2.0, preferably 0.3 to 1.0 kg of adiponitrile / 1 * h is preferably used here. In this case also, the conversion and consequently the selectivity can be adjusted in a specific way through the variation of the residence time. The process of the present invention provides alpha, omega-a inanitriles with good selectivities and with minimal amounts of hexamethylenediamine. In addition, the catalysts used in accordance with the present invention have a residence time in the stream definitely longer than comparable catalysts of the prior art.

Alpha, omega-aminani tri are important initial compounds for the preparation of cyclic lactams, especially 6-aminocapranitrile for capralacta. Ex emplos The phase encapsulations of the catalysts were determined by XRD. The following abbreviations were used: DNA = adipolyitrila (sic), HMD = hexamethylenediamine, ACN = 6-aminocapronitrile Example 1 according to the present invention: A tubular reactor of 1800 m in length and 30 mm in internal diameter was charged with 740 ml (720 g) of a catalyst consisting of 487. CoO, 0.67. of Na2Q, the rest being Fe203.

The catalyst was activated in a hydrogen / nitrogen stream at a temperature of 230 ° C under atmospheric pressure. Initially the speed of N2 was 450 1 / h and the speed of H2 was 50 1 / h. Over the course of the next 8 hours, the H2 content of the reducing gas was progressively elevated to 100%. After 8 hours, the reducing current was pure hydrogen. This was followed by an additional 12 hours of activation with 500 1 / h of H2 at a temperature of 250 ° C under atmospheric pressure. After reducing the temperature to 65 ° C (inlet) or 80 ° C (outlet), the reactor was fed at 200 bar with a mixture of 400 ml / h of adipanitrile, 640 ml / h of ammonia and 500 1 / h of hydrogen by the upflow method To remove the heat of the reaction, 4 or 5 liters of the reactor effluent were cooled and recycled to the reactor, under these conditions, the conversion of adiponitrile is 75%. the reaction consisted essentially of 257. of DNA, 37% of ACN and 377. of HMD After 2600 hours, the catalyst continued to perform the same selectivity as the fresh catalyst and with an unchanged activity. (a) was 507. by weight, and the iron oxide content of compound (b) was 30% by weight Comparative Example i: Three tubular reactors connected in series were charged (total length: 4.5 m, d = 6 m) with 90 ml (107 g) of the catalyst of Example 1 and after were used in a current of 200 1 / h of hydrogen under atmospheric pressure. Fara this purpose, 1T temperature was elevated from 50 to 340 ° C in 24 hours and then maintained at 340 ° C for 72 hours. After the decrease in temperature to IOC'C, the reactor was fed at 200 bar with a mixture of 50 ml / h of DNA, 280 ml of NH3 and 200 standard 3 / h of H2. No conversion was achieved. The metallic cobalt content of component (a) was 907 by weight, and the iron oxide content of component (b) was 16% by weight. Comparative Example 2: Three tubular reactors connected in series (total length: 4.5 m, d = 6 mm) were charged with 90 ml (107 g) of the catalyst of Example 1 and then reduced in a current of 200 l / h of hydrogen under atmospheric pressure. For this purpose, the temperature was elevated from 50 to 200 ° C in 3 hours and then maintained at 200 ° C for 12 hours. After the temperature drop to 75 * C, the reactor was fed at 200 bar with a mixture of 50 ml / h of DNA, 280 ml of NH3 and 200 standard 1 / h of H2. A conversion of 507 DNA was achieved under these conditions. The reaction mixture consisted essentially of 50% DNA, 40% ACN and 10% HMD. Said reactor effluent was obtained in a period of 300 hours. After 300 hours, the feeds were suspended except in the case of NH3 and H2. After a rinsing period of 12 hours, the NH3 feed was also suspended, and the catalyst was reactivated with 200 1 / h of H2 at a temperature of 340 ° C under atmospheric pressure for 72 hours. For this purpose, the temperature was elevated from 50 ° C to 340 ° L;, C in 24 hours and then maintained at 340 ° C for 72 hours. After the decrease in temperature to 80 ° C, the reactor was fed at 250 bar with a mixture of 50 ml / h of DNA, 230 ml / h of NH 3 and 200 ml / h of H2. No conversion was achieved under these conditions or after the rise in temperature to 120 aC.

Claims (8)

1. CLAIMS i. A suitable catalyst for the preparation of aliphatic alpha, omega-aminonitri by the partial hydrogenation of aliphatic dinitriles, comprising (a) cobalt metal, a cobalt compound or a mixture thereof, the proportion of metallic cobalt, based on (a) is from 20 to 1007. by weight, b) from 10 to 70% by weight, based on (a), of metallic iron, iron oxide, an additional iron compound or a mixture thereof, the proportion of iron oxide, based on (b) is from 20 to 100% by weight, (c) from 0 to 17. by weight, based on the sum of (a) and (b), of a campuesto based on an alkali metal, an alkaline earth metal or zinc.
2. 2. A catalyst according to claim 1 in the form of an unsupported catalyst.
3. 3. A catalyst according to claim 1 in the form of a supported catalyst.
4. 4. A process for the preparation of alpha, amega-aminonitriles by the partial hydrogenation of aliphatic dinitriles at elevated temperature and under elevated pressure in the presence of a catalyst according to any of claims 1 to 3.
5. 5. A process in accordance with Claim 4, wherein the hydrogenation is carried out in a fixed bed reactor.
6. 6. A process according to claim 4 or 5, wherein the adipanitrila is used as the alpha, amega-dinitrila in order to obtain 6-aminscapranitri lo.
7. 7. A process according to any of claims 4 to 6, wherein the hydraging is carried out at a pressure that is within the range of 2 to 30 MPa.
8. 8. A process according to any of claims 4 to 7, wherein the hydrogenation is carried out at a temperature within the range of 20 to