Process for the preparation of 3-aminomethyl-3,5,5-trimethylcyclohexylamine

Description

[0001] The invention relates to an improved process for the preparation of 3-aminomethyl-3,5,5-trimethylcyclohexylamine, hereinafter referred to as isophoronediamine or abbreviated as IPDA, by means of catalytic hydrogenation and / or catalytic reductive amination (also referred to as aminating hydrogenation) of 3-cyano-3,5,5-trimethylcyclohexanone, hereinafter referred to as isophoronenitrile or abbreviated as IPN.

[0002] The production of IPDA by aminating hydrogenation of IPN is known and has been described several times.

[0003] In the simplest case (US 3,352,913), IPN is reacted in the presence of hydrogen and an excess of ammonia over a cobalt catalyst. Initially, the isophorone nitrile imine (IPNI) is formed from IPN and ammonia by dehydration, which is subsequently hydrogenated to IPDA.

[0004] The yield of IPDA in this reaction is largely determined by the excess of ammonia. The maximum IPDA yield achieved is approximately 80%. The main byproduct is the so-called amino alcohol, IPAA, which results from the direct hydrogenation of IPN.

[0005] A significant increase in IPDA yield is achieved when the formation of IPNI is accelerated by using suitable imination catalysts. Suitable imination catalysts include acidic ion exchange resins (EP 042 119). Acidic metal oxides (EP 449 089), organopolysiloxanes containing sulfonic acid groups (EP 816 323), heteropolyacids (DE 44 26 472), and activated carbon (EP 061 137) can also be used as imination catalysts. In addition to reducing the undesired amino alcohol, other byproducts are also significantly reduced, such as bicyclic compounds and byproducts resulting from the elimination of HCN.

[0006] The problem of HCN cleavage from gamma-ketonitriles, such as IPN, is particularly highlighted in the literature (US Pat. No. 3,352,913). Firstly, it is noted that HCN cleavage reduces the yield of IPDA (EP 042 119, DE 44 26 472).

[0007] Furthermore, it is pointed out that HCN acts as a catalyst poison and leads to deactivation of the hydrogenation catalyst (EP 394 967 A1, page 2, line 34 ff, page 3, line 44 ff). It is therefore recommended to carry out the imination step in such a way that as little HCN as possible is released.

[0008] According to EP 913 387, quaternary ammonium bases can also be used to increase selectivity in the production of IPDA. Accordingly modified catalysts exhibit a significantly longer service life than alkali-modified catalysts, especially when a solvent is used. WO 2005 / 039764 A discloses a Raney catalyst.

[0009] Furthermore, processes for the preparation of isophoronediamine are known from CN 104230721A, EP 2649042A, WO 2008107226A and WO 2012126869A.

[0010] JP S62 123154 A discloses a process for producing isophorone nitrile. JP H07 188126 A discloses a process for producing isophoronediamine from isophorone nitrile.

[0011] The underlying task was to find a process for the preparation of 3-aminomethyl-3,5,5-trimethylcyclohexylamine by hydrogenation of isophoronenitrile, whereby the yield and selectivity in the reductive amination of isophoronenitrile to produce isophoronediamine should be improved.

[0012] Surprisingly, a new catalyst was discovered, as described in more detail below. As an additional unexpected effect, higher activity, allowing lower reaction temperatures, and improved long-term stability of the catalyst were observed.

[0013] Typically, processes for the preparation of 3-aminomethyl-3,5,5-trimethylcyclohexylamine by hydrogenation of isophorone nitrile employ catalysts in the form of powders or shaped bodies, such as extrudates or pressed powders. Solid catalysts, Raney-type catalysts, or supported catalysts can be used. Raney-type and supported catalysts are preferred, as described in detail in EP 2649042A.

[0014] Surprisingly, it has now been found that the catalyst used according to the invention, consisting of a metal alloy in granular form of certain particle sizes, after activation by alkalis, solves the problem of the invention and, in addition, a higher activity and better long-term stability of the catalyst were found.

[0015] The invention relates to a process for the preparation of isophoronediamine, characterized in that A) isophoronenitrile is hydrogenated directly in one step in the presence of ammonia, hydrogen, a hydrogenation catalyst and optionally further additives and in the presence or absence of organic solvents to give isophoronediamine; or B) isophoronenitrile is first converted wholly or partly into isophoronenitrile imine in at least two or more steps, and this isophoronenitrile imine is hydrogenated as a pure substance, or in a mixture with other components and / or isophoronenitrile, in the presence of at least ammonia, hydrogen and a catalyst to give isophoronediamine; wherein the catalyst has the following properties: I. The catalyst, after activation, has the following composition in weight percent (wt%), where the proportions add up to 100 wt%, based on the metals contained: Cobalt: 55 to 85 wt.% Aluminum: 5 to 43.5 wt% Chrome: 0.5 to 3 wt.% Nickel: 1 to 7 wt.% And II. The catalyst is in the form of irregular particles as granules and, after activation, has particle sizes of 1 to 8 millimeters (mm) measured by sieving. Catalyst

[0016] The catalyst consists of a metal alloy, with the metal alloy being activated by bases on its surface. The thickness of the activated layer on the catalyst particle surface is preferably 50 to 1000 micrometers (µm). However, it can also be larger or smaller. The catalytically active composition of the catalyst is therefore located on the surface. However, it is also possible within the scope of the invention to leach the entire catalyst particle almost completely or completely.

[0017] After activation, the catalyst used according to the invention is present as granules in the form of individual particles.

[0018] The catalyst used according to the invention has, after activation, the following composition in its entirety in weight percent (wt.%), where the proportions add up to 100 wt.%, based on the metals contained: 1. Variant Cobalt: 55 to 85 wt.% Aluminum: 5 to 43.5 wt% Chrome: 0.5 to 3 wt.% Nickel: 1 to 7 wt.% 2nd variant Cobalt: 57 to 84 wt.% Aluminum: 10 to 40 wt.% Chrome: 1 to 2 wt.% Nickel: 2 to 4 wt.%

[0019] Totality means that the composition does not differentiate between the content of metals on the surface and in the activated layer and in the core of the catalyst particles, but everything is added together and calculated.

[0020] The catalyst is in the form of irregular particles, i.e. granules.

[0021] In addition, the catalyst used according to the invention has the following particle sizes after activation: In general, the catalyst, i.e. the granulate particles, has particle sizes of 1 to 8 millimeters (mm) measured by sieving.

[0022] In a first preferred variant of the invention, the particle sizes of the catalyst, i.e. the granulate particles, vary from 2.5 to 6 millimeters (mm).

[0023] In a second preferred variant of the invention, the particle sizes of the catalyst, i.e. the granulate particles, vary from 3 to 7 millimeters (mm).

[0024] In a third preferred variant of the invention, the particle sizes of the catalyst, i.e. the granulate particles, vary from 2 to 5 millimeters (mm).

[0025] The specified particle sizes may also exhibit a statistical distribution within the ranges. Both narrow and broad distributions are possible according to the invention.

[0026] Particle size determination is described in DIN ISO 9276-1 (September 2004), 9276-2 (February 2006), 9276-4 (February 2006), and 9276-6 (January 2012). Detailed information on particle size definition, particle size distribution, and particle size measurement can also be found in HORIBA ®< Scientific, A GUIDEBOOK TO PARTICLE SIZE ANALYSIS, 2012, by HORIBAO Instruments, Inc., Irvine, USA.

[0027] According to the invention, the particle size distribution and the particle size measurement can be determined by laser methods (ISO 13320, 2012), light methods or image methods.

[0028] The catalyst used according to the invention is preferably obtained by sieving the granules produced. This produces so-called sieve fractions. Individual sieve fractions can be mixed, or a catalyst can be obtained by single or repeated sieving. The catalysts produced in this way exhibit a statistical particle size distribution, usually in the form of a Gaussian distribution. Symmetrical and asymmetrical distributions are possible.

[0029] In a fourth preferred variant of the invention, the particle sizes of the catalyst, i.e. the granulate particles, vary with a statistical distribution between 2.5 and 5.5 millimeters (mm), whereby up to 10 percent of the particles can also lie outside the stated range of the stated lower limit or upper limit, but also up to 10 percent each outside the stated range of the stated lower limit and upper limit.

[0030] In a fifth preferred variant of the invention, the particle sizes of the catalyst, i.e. the granulate particles, vary with a statistical distribution between 3.5 and 6.5 millimeters (mm), whereby up to 10 percent of the particles can also lie outside the stated range of the stated lower limit or upper limit, but also up to 10 percent each outside the stated range of the stated lower limit and upper limit.

[0031] In a sixth preferred variant of the invention, the particle sizes of the catalyst, i.e. the granulate particles, vary with a statistical distribution between 2 and 5 millimeters (mm), whereby up to 10 percent of the particles can also lie outside the stated range of the stated lower limit or upper limit, but also up to 10 percent each can lie outside the stated range of the stated lower limit and upper limit.

[0032] In a seventh preferred variant of the invention, the particle sizes of the catalyst, i.e. the granulate particles, vary with a statistical distribution between 3 and 7 millimeters (mm), whereby up to 10 percent of the particles can also lie outside the stated range of the stated lower limit or upper limit, but also up to 10 percent each can lie outside the stated range of the stated lower limit and upper limit.

[0033] Suitable methods and descriptions for sieve analysis are described in: DIN 66165-1:1987-04 Particle size analysis; Sieve analysis; Fundamentals, and DIN 66165-2:1987-04 Particle size analysis; Sieve analysis; Implementation. Paul Schmidt, Rolf Körber, Matthias Coppers: Sieving and sieving machines: Fundamentals and application. Wiley-VCH Verlag, 2003, ISBN 9783527302079, Chapter 4.4: Analytical sieving. Jörg Hoffmann: Handbook of measurement technology. Hanser Verlag, 2007, ISBN 978-3-446-40750-3, Chapter 3.12.16.2.1.

[0034] The catalyst used according to the invention particularly preferably has, after activation, the following composition in its entirety in weight percent (wt.%), where the proportions add up to 100 wt.%, based on the metals contained: Cobalt: 57 to 84 wt.% Aluminum: 10 to 40 wt.% Chrome: 1 to 2 wt.% Nickel: 2 to 4 wt.% and with Particle sizes of the catalyst, i.e. the granulate particles with a statistical distribution between 2.5 and 5.5 millimeters (mm), or particle sizes of the catalyst, i.e. the granulate particles with a statistical distribution between 3.5 and 6.5 millimeters (mm), or particle sizes of the catalyst, i.e. the granulate particles with a statistical distribution between 2 and 5 millimeters (mm), or particle sizes of the catalyst, i.e. the granulate particles with a statistical distribution between 3 and 7 millimeters (mm), whereby up to 10 percent of the particles can also lie outside the stated range of the stated lower limit or upper limit, but also up to 10 percent each can lie outside the stated range of the stated lower limit and upper limit.

[0035] General method for preparing the catalyst: a) Production of the alloy

[0036] The alloy is produced thermally, for example, in an induction furnace. The metals are melted to form an alloy. The finished melt is then cast into bars for further processing. b) Production of the granules

[0037] The alloy is processed into granules using suitable equipment, for example, pre-crushed using a jaw crusher and further ground using a roller mill. A sieving step ensures the desired size distribution of the granules by selecting the appropriate sieves (e.g., 3-7 mm). c) Activation of the catalyst

[0038] The catalyst is activated in suitable equipment. Organic or inorganic bases can be used. A caustic solution (e.g., sodium hydroxide solution) is preferred, whereby an exothermic process dissolves part of the aluminum from the alloy, forming hydrogen and aluminate solution. The concentration of the caustic solution can be between 5 and 30 wt.%, and the reaction temperature can be between 50 and 100°C. The degree of activation is determined by the temperature and reaction time. The reaction time is variable and depends on the reaction conditions and the desired degree of activation. After activation, the catalyst is washed with water and then stored underwater.

[0039] Other compositions can be produced analogously in production step a) by selecting the appropriate metal quantities.

[0040] The catalyst is preferably prepared in the sequence described. However, the catalyst can also be activated before the granules are produced.

[0041] To increase activity, selectivity, and / or service life, the catalysts may additionally contain doping metals or other modifiers. Typical doping metals include Mo, Fe, Ag, V, Ga, In, Bi, Ti, Zr, and Mn, as well as rare earths, alone or in mixtures. Typical modifiers include those that can influence the acid-base properties of the catalysts, preferably alkali and alkaline earth metals or their compounds, preferably Mg and Li compounds. If such compounds are present, in an amount of a maximum of approximately 5% by weight, the proportion of the above-mentioned metals Co and Al, as well as optionally Cr and Ni, in the catalyst is reduced accordingly, with the proportions of Co and Al, as well as optionally Cr and Ni, then adding up to at least 95% by weight after activation, based on the metals present.

[0042] It is possible to carry out the process according to the invention in one step or in at least two or more steps.

[0043] If the process is carried out in one step, isophorone nitrile is hydrogenated directly in the presence of ammonia, hydrogen, a catalyst and optionally further additives and in the presence or absence of organic solvents.

[0044] The term "in at least two or more stages" means that isophoronenitrile is first converted in whole or in part into isophoronenitrile imine in a separate reactor or reactor section, and this isophoronenitrile imine is subjected to aminating hydrogenation as a pure substance or in a mixture with other components, such as unreacted isophoronenitrile, in the presence of at least ammonia and hydrogen and a catalyst.

[0045] A preferred embodiment of the process according to the invention for producing IPDA is a two-stage process: In the first stage, at least a portion of the IPN used is converted into isophorone nitrile imine by reaction with ammonia, in the presence or absence of an imination catalyst and / or solvents. The conversion of IPN to IPNI after imination should be greater than 80%, preferably greater than 90%, particularly preferably greater than 95%.

[0046] In the second stage, the reaction product of the first stage, as it is obtained or after further treatment and / or addition of further ammonia, is subjected to aminating hydrogenation over hydrogenation catalysts in the presence of at least ammonia and hydrogen and in the presence or absence of an organic solvent at a temperature of 20 to 150 °C, preferably 40 to 130 °C, and a pressure of 0.3 to 50 MPa, preferably 5 to 30 MPa.

[0047] In a further preferred embodiment, the conversion of IPN to IPDA takes place in three separate reaction chambers. In the first reaction chamber, the conversion of IPN to isophoronenitrile imine takes place with excess ammonia over imination catalysts at temperatures between 20 and 150 °C and pressures between 5 and 30 MPa. In the second reaction chamber, the resulting reaction products are hydrogenated with hydrogen in the presence of excess ammonia over hydrogenation catalysts at temperatures between 20 and 130 °C and pressures between 5 and 30 MPa. In the third reaction chamber, the resulting reaction products are hydrogenated over the catalysts to be used according to the invention at temperatures between 100 and 160 °C and pressures between 5 and 30 MPa.

[0048] To accelerate the equilibration of the imination reaction, it is advantageous to use an imination catalyst. Imination catalysts known from the prior art can be used for this purpose. Suitable catalysts include, for example, inorganic or organic ion exchangers (see EP 042 119), supported heteropolyacids (see DE 44 26 472), acidic metal oxides, in particular aluminum oxide and titanium dioxide (see EP 449 089), organopolysiloxanes containing sulfonic acid groups (DE 196 27 265.3), acidic zeolites, and activated carbon (EP 061 137). When using an imination catalyst, the reaction temperature can be between 10 and 150 °C, preferably between 30 and 130 °C, and very particularly preferably between 40 and 100 °C. The pressure is between the intrinsic pressure of the mixture and 50 MPa. Preferably, the imination reaction is carried out at the pressure at which the subsequent reductive amination is carried out.

[0049] Although the imination of isophoronenitrile with liquid ammonia is preferably carried out without the addition of additional solvents, it can also be carried out in the presence of additional solvents. Suitable solvents include monohydric alcohols with 1 to 4 carbon atoms, especially methanol, as well as ethers, especially THF, MTBE, and dioxane.

[0050] In the imination stage, between 1 and 500 mol, preferably between 5 and 200 mol, and particularly preferably between 5 and 100 mol of ammonia are used per mole of IPN used. Typical catalyst loadings are in the range of 0.01 to 10 kg of IPN per kg of catalyst per hour, preferably 0.5 to 10, and particularly preferably 0.5 to 5 kg of IPN per kg of catalyst per hour.

[0051] When imination is carried out in the presence of an imination catalyst, the catalyst can be in the form of a suspended catalyst or a fixed-bed catalyst. The use of fixed-bed catalysts is advantageous. In a particularly preferred embodiment, IPN and ammonia are continuously passed from bottom to top through a reaction tube filled with imination catalyst.

[0052] Hydrogenation takes place in fixed-bed reactors. Suitable reactor types include shaft furnaces, tray reactors, or tube-bundle reactors.

[0053] Hydrogenation is typically carried out at temperatures between 20 and 150 °C, preferably between 40 and 130 °C, and pressures between 0.3 and 50 MPa, preferably between 5 and 30 MPa. It is also possible to carry out the hydrogenation in the presence of the solvents already mentioned in the imination step. The main advantage of using a solvent is that the hydrogenation can be carried out at lower pressures between 0.3 and 10 MPa.

[0054] The hydrogen required for hydrogenation can be fed into the reactor either in excess, for example, up to 10,000 molar equivalents, or in a quantity sufficient to replenish the hydrogen consumed by the reaction and the portion of hydrogen leaving the reactor dissolved in the product stream. In continuous operation, the hydrogen can be fed in cocurrent or countercurrent.

[0055] In a preferred embodiment, the hydrogenation is carried out in liquid ammonia as the solvent. Between 1 and 500 mol, preferably between 5 and 200 mol, and particularly preferably between 5 and 100 mol of ammonia are used per mole of IPN. It is advisable to use at least the amount of ammonia that was established during the preceding imination. However, the ammonia content can also be increased to the desired value before hydrogenation by adding additional ammonia.

[0056] The required volume of hydrogenation catalysts to be used depends on the LHSV (liquid hourly space velocity), which depends on the operating pressure, temperature, concentration, and catalyst activity and must be maintained to ensure the most complete hydrogenation of the IPN used. When using the preferred mixture of IPN, ammonia, and hydrogen, the LHSV is typically between 0.5 and 5 liters of IPN / ammonia mixture per liter of catalyst per hour, preferably between 1 and 4 liters of solution per catalyst per hour.

[0057] It is preferred that the hydrogenation catalysts to be used are first conditioned with ammonia before being used in the hydrogenation. For this purpose, the catalysts are brought into contact with ammonia or with mixtures of ammonia and one or more solvents. Conditioning is preferably carried out after installation of the catalysts in the hydrogenation reactor, but it can also be carried out before installation of the catalysts. For conditioning, between 0.2 and 3, preferably 0.5 and 2 m³ of ammonia per m³ of catalyst per hour are used. Temperatures are usually between 20 and 150°C, preferably 40 to 130°C. Particular preference is given to running through a temperature ramp in which the catalyst is heated slowly, starting at a moderately elevated temperature, preferably between 20 and 50°C, to the reaction temperature subsequently desired for the hydrogenation, preferably 20 to 150°C.Conditioning is preferably carried out in the presence of hydrogen, with the partial pressure of the hydrogen used in the reactor ranging from 0.1 to 50 MPa, preferably 5 to 40 MPa, particularly preferably 10 to 30 MPa. The conditioning time depends on the amount of ammonia used and is preferably between 1 and 48 hours, particularly preferably between 12 and 24 hours.

[0058] In the preferred two-stage process, the mixture containing isophorone nitrile imine is hydrogenated in the presence of the hydrogenation catalyst in the second stage. The mixture fed to the hydrogenation stage can be directly that obtained from the imination of IPN with ammonia in the first stage, or as obtained after the addition or removal of components such as ammonia, organic solvents, bases, cyanide salts, hydrogen cyanide, and / or water. The hydrogenation is preferably carried out continuously in fixed-bed reactors that can be operated in trickle-bed or liquid-phase mode. Suitable reactor types include shaft furnaces, tray reactors, or tube-bundle reactors. It is also possible to connect several fixed-bed reactors in series for the hydrogenation, with each of the reactors being operated optionally in trickle-bed or liquid-phase mode.

[0059] In addition to the aforementioned components of the mixture fed to the imination stage, it may also contain fractions boiling higher or lower than IPDA from the distillative workup of the reaction mixture withdrawn from the trickle-bed reactor. Such fractions may contain, in addition to residual IPDA, by-products from which IPDA is reformed under reaction conditions. It is particularly advantageous to recycle the fraction boiling above IPDA, which, in addition to residual IPDA, contains 2-aza-4,6,6-trimethylbicyclo[3.2.1]octane as the main product. It is also particularly advantageous to recycle incompletely converted IPN, in particular fractions containing isophoroneaminonitrile. If desired, the recycles can also be added directly to the reaction mixture fed to the hydrogenation stage.

[0060] During the hydrogenation of IPN or isophorone nitrile imine, two different stereoisomers can be formed. The isomer ratio can be influenced by selecting a temperature profile in the hydrogenation step. For example, it is possible to initially partially hydrogenate a mixture containing IPN or isophorone nitrile imine at a temperature between 20 and 90 °C and then complete the reaction in a second step in a temperature range between 90 and 150 °C. By maintaining relatively low reaction temperatures in the first step, the selectivity can be shifted in favor of the cis isomer. Maintaining relatively low reaction temperatures at the beginning of the reaction also has the advantage that the thermally labile isophorone nitrile imine is hydrogenated particularly gently, thus preventing side reactions.The intermediately formed isophoroneaminonitrile is thermally significantly more stable and can therefore be hydrogenated at higher temperatures without fear of further side reactions. Undesirable side reactions also include the release of HCN. According to the process according to the invention, a certain concentration of cyanide ions has a positive effect on the selectivity of the hydrogenation stage. This effect is more pronounced when the cyanide ions are present from the beginning of the hydrogenation stage and are not formed during the hydrogenation. Therefore, the release of HCN during the hydrogenation stage must be prevented.

[0061] The desired temperature profile can be achieved, for example, by connecting two or more separately heated reactors in series. However, it is also possible to achieve an increasing temperature profile in a single hydrogenation reactor. The hydrogenation reaction is particularly preferably carried out in an adiabatically operated trickle-bed reactor, in which the reaction mixture is fed into the reactor at temperatures between 20 and 90 °C and leaves again between 90 and 150 °C due to the reaction heat generated and absorbed by the reaction mixture.

[0062] The reaction mixture leaving the hydrogenation process is further purified using conventional methods to obtain IPDA of the desired quality. All common separation methods can be used, such as distillation, flash evaporation, crystallization, extraction, sorption, permeation, phase separation, or combinations of the above. The purification can be carried out continuously, batchwise, in one or more stages, under vacuum or under pressure. Possible components that are separated during further purification include hydrogen, ammonia, water, and by-products arising from the production of IPDA from IPN, such as hydrogenated HCN elimination products or IPN impurities, methylated by-products, and / or incompletely hydrogenated intermediates.

[0063] Purification is preferably achieved by distillation under pressure and / or vacuum in several steps. Any distillation column, with or without internals such as dephlegmators, dividing walls, random internals or packings, ordered internals or packings, and trays with or without forced flow, can be used for this purpose.

[0064] In a first step, in particular hydrogen, inert gases, ammonia, low-boiling impurities and possibly also water are completely or partially separated in one or more distillation columns. The separation preferably takes place at a pressure lower than that in the reaction step. If the separation takes place in several distillation steps, it is advantageous to reduce the pressure step by step. The separation is most preferably carried out above 1 bar and at bottom temperatures of 0 - 200 °C. The use of a stripping gas to remove low-boiling impurities can be advantageous. In particular, ammonia and hydrogen and portions of the low-boiling impurities can be fully or partially recycled into the process (reaction). The low-boiling impurities and, if appropriate, portions of hydrogen and ammonia are fed for thermal utilization.

[0065] In a second step, further low-boiling impurities, water, and high-boiling impurities are partially or completely separated. This can be done in one or more distillation columns. Water, together with organic, low-boiling impurities and, if present, portions of IPDA, can be distilled off at the top of the column and, after condensation, separated into an aqueous and an organic phase. Part of the organic phase can be returned to the column as reflux. If the second distillation step is carried out in a single column (e.g., a dividing wall column), the IPDA with the desired purity is withdrawn via a side stream, while the high-boiling impurities are collected in the bottom of the column. However, if the separation is carried out in two or more stages, the IPDA is obtained at the top of a column.The separation of low-boiling and high-boiling impurities and water is preferably carried out in a vacuum between 100 Pa and 0.0999 MPa and at sump temperatures of 50 - 300 °C. All secondary components can be recycled for thermal energy. Example Production of the catalyst, co-granulate: c) Production of the alloy

[0066] The alloy is produced in an induction furnace. The metals are melted in the appropriate quantities at 1500°C. The finished melt is cast into ingots for further processing. d) Production of the granules

[0067] The alloy ingots are pre-crushed using a jaw crusher and further ground using a roller mill. A sieving step ensures the desired size distribution of the granules by selecting the appropriate sieves. a) Activation of the catalyst

[0068] The catalyst is activated in a standard glass laboratory apparatus, such as a beaker. An aqueous alkali (e.g., sodium hydroxide solution) is added to the granules while stirring. During activation, the granules are placed in a catalyst basket. An exothermic process dissolves a portion of the aluminum from the alloy, forming hydrogen and sodium aluminate alkali. The alkali concentration used was 20 wt.%, and the reaction temperature was 90 °C. The degree of activation was determined by the reaction time. After activation, the catalyst is washed with water and then stored underwater.

[0069] After activation, the catalyst used has the following composition in weight percent (wt%), where the proportions add up to 100 wt%, based on the metals contained: Cobalt: 75.9% by weight Aluminum: 20.0 wt.% Chrome: 1.5 wt.% Nickel: 2.6 wt.%

[0070] A sieve fraction was used with particle sizes of the catalyst, i.e. the granulate particles with a statistical distribution between 2.0 and 5.0 millimeters (mm), whereby up to 10 percent of the particles can also lie outside the stated range of the stated lower limit or upper limit, but also up to 10 percent each outside the stated range of the stated lower limit and upper limit. Production of IPDA with the used in the invention catalyst

[0071] The catalysts are tested for their catalytic activity in the production of 3-aminomethyl-3,5,5-trimethylcyclohexylamine (isophoronediamine, IPDA) from 3-cyano-3,5,5-trimethylcyclohexanone (isophoronenitrile, IPN) in a two-step process.

[0072] In the first stage, isophoronenitrile is at least partially converted to 3-cyano-3,5,5-trimethylcyclohexanimine in the presence of an imination catalyst using ammonia. In the second stage, it is subjected to aminating hydrogenation over a hydrogenation catalyst at a temperature of 60-100°C and a pressure of 250 bar using hydrogen in the presence of ammonia. Each stage of the production process is carried out in a separate reactor. However, both reactors are connected in series and are individually temperature-controlled.

[0073] The hydrogenation reactor is filled with 42 ml of the catalyst to be tested. The feed solution of IPN (15 wt%) and ammonia (85 wt%) is pumped from top to bottom through the reaction tube at a mass flow rate of 110 ml / h. Hydrogen is added separately from the top at a volume flow rate of 40 l / h. The product liquid is collected in a separator vessel below the reactor. The collected product mixture is analyzed for IPDA and corresponding secondary components by gas chromatography. The results are listed in Table 1. Table 1 temperature Yield IPDA / GC-% Sales volume / % 100 °C 98,1 99,5 80 °C 96,7 98,5 60 °C 92,1 93,1 Long-term stability

[0074] In the first step, isophoronenitrile is at least partially converted to 3-cyano-3,5,5-trimethylcyclohexanimine in the presence of an imination catalyst using ammonia. In the second step, it is subjected to aminating hydrogenation over a hydrogenation catalyst at a temperature of 60 °C (inventive catalyst) or 100 °C (reference catalyst, supported pressed co-molded body) and a pressure of 250 bar using hydrogen in the presence of ammonia. Each production step is carried out in a separate reactor. However, both reactors are connected in series and are individually temperature-controlled.

[0075] To test long-term stability, the hydrogenation reactor is filled with 100 ml of the catalyst to be tested. The feed solution of IPN (22 wt.%) and ammonia (78 wt.%) is pumped from top to bottom through the reaction tube at a mass flow rate of 120 g / h. Hydrogen is also added from the top at a volume flow rate of 50 l / h. The product liquid is collected in a separator vessel below the reactor. The collected product mixture is analyzed for IPDA and corresponding secondary components by gas chromatography. The results are shown in Figure 1 listed.

[0076] Catalyst used according to the invention Co-granulate of the composition as described above Reference catalyst: Supported pressed co-catalyst shaped body

Claims

1. Process for preparing isophoronediamine, characterized in that A) isophoronenitrile is subjected directly in one stage to aminating hydrogenation to give isophoronediamine in the presence of ammonia, hydrogen, a hydrogenation catalyst and possibly further additions, and in the presence or absence of organic solvents; or B) isophoronenitrile is first converted fully or partly in at least two or more than two stages to isophoronenitrile imine, and this isophoronenitrile imine is subjected to aminating hydrogenation to give isophoronediamine as a pure substance or in a mixture with other components and / or isophoronenitrile, in the presence of at least ammonia, hydrogen and a catalyst, wherein the catalyst has the following properties: I. The catalyst has, after the activation, in its entirety, the following composition in per cent by weight (% by weight), where the proportions add up to 100% by weight, based on the metals present: Cobalt: 55% to 85% by weight Aluminium: 5% to 43.5% by weight Chromium: 0.5% to 3% by weight Nickel: 1% to 7% by weight and II. The catalyst is in the form of irregular particles as a granular material and after activation has particle sizes of 1 to 8 millimetres (mm) measured by screening.

2. Process for preparing isophoronediamine according to Claim 1, characterized in that I. The catalyst has, after the activation, in its entirety, the following composition in per cent by weight (% by weight), where the proportions add up to 100% by weight, based on the metals present: Cobalt: 57% to 84% by weight Aluminium: 10% to 40% by weight Chromium: 1% to 2% by weight Nickel: 2% to 4% by weight3. Process for preparing isophoronediamine according to at least one of the preceding Claims 1-2, characterized in that the particle sizes of the catalyst, i.e. the granulate particles, vary from 2.5 to 6 millimetres (mm), or the particle sizes of the catalyst, i.e. the granulate particles, vary from 3 to 7 millimetres (mm), or the particle sizes of the catalyst, i.e. the granulate particles, vary from 2 to 5 millimetres (mm).

4. Process for preparing isophoronediamine according to at least one of the preceding Claims 1-2, characterized in that the catalyst is obtained by screening the granules produced.

5. Process for preparing isophoronediamine according to Claim 4, characterized in that the catalyst is obtained by screening the granules produced, and the particle sizes of the catalyst, i.e. the granulate particles, having a statistical distribution between 2.5 to 5.5 millimetres (mm), or the particle sizes of the catalyst, i.e. the granulate particles, having a statistical distribution between 3.5 to 6.5 millimetres (mm), or the particle sizes of the catalyst, i.e. the granulate particles, having a statistical distribution between 2 to 5 millimetres (mm), or the particle sizes of the catalyst, i.e. the granulate particles, having a statistical distribution between 3 to 7 millimetres (mm), and where up to 10 per cent of the particles may also be outside said range of said lower limit or upper limit, but up to 10 percent in each case may also be outside said range of said lower limit and upper limit.

6. Process for preparing isophoronediamine according to Claim 1, characterized in that the catalyst has, after the activation, in its entirety, the following composition in per cent by weight (% by weight), where the proportions add up to 100% by weight, based on the metals present: Cobalt: 57% to 84% by weight Aluminium: 10% to 40% by weight Chromium: 1% to 2% by weight Nickel: 2% to 4% by weight and comprising particle sizes of the catalyst, i.e. the granulate particles, having a statistical distribution between 2.5 to 5.5 millimetres (mm), or particle sizes of the catalyst, i.e. the granulate particles, having a statistical distribution between 3.5 to 6.5 millimetres (mm), or particle sizes of the catalyst, i.e. the granulate particles, having a statistical distribution between 2 to 5 millimetres (mm), or particle sizes of the catalyst, i.e. the granulate particles, having a statistical distribution between 3 to 7 millimetres (mm), where up to 10 per cent of the particles may also be outside said range of said lower limit or upper limit, but up to 10 per cent in each case may also be outside said range of said lower limit and upper limit.

7. Process for preparing isophoronediamine according to at least one of the preceding claims, characterized in that the catalysts additionally comprise doping metals, preferably selected from Mo, Fe, Ag, V, Ga, In, Bi, Ti, Zr and Mn, and the rare earths.

8. Process for preparing isophoronediamine according to at least one of the preceding claims, characterized in that catalysts comprise modifiers, preferably alkali metals and alkaline earth metals or compounds thereof, preferably magnesium and lithium compounds.

9. Process for preparing isophoronediamine according to at least one of the preceding claims, characterized in that at least some of the isophoronenitrile imine used is converted to isophoronenitrile imine in the first stage by reaction with ammonia in the presence or absence of an imination catalyst and / or of solvents, the conversion of IPN to IPNI after the imination being greater than 80%, preferably greater than 90%, particularly preferably greater than 95%.

10. Process for preparing isophoronediamine according to at least one of the preceding claims, characterized in that the first stage reaction product, as obtained or after a further treatment and / or addition of further ammonia, is subjected in the second stage to aminating hydrogenation over hydrogenation catalysts in the presence of at least ammonia and hydrogen and in the presence or absence of an organic solvent at a temperature of 20 to 150°C, preferably 40 to 130°C, and a pressure of 0.3 to 50 MPa, preferably 5 to 30 MPa.

11. Process for preparing isophoronediamine according to at least one of the preceding claims, characterized in that the conversion of IPN to IPDA is effected in three separate reaction spaces, IPN being converted to isophoronenitrile imine with excess ammonia over imination catalysts in the first reaction space at temperatures between 20 and 150°C and pressures between 5 and 30 MPa, the reaction products formed being hydrogenated with hydrogen in the presence of excess ammonia over hydrogenation catalysts in the second reaction space at temperatures between 20 and 130°C and pressures of 5 to 30 MPa, and the reaction products formed being hydrogenated over catalysts in the third reaction space at temperatures between 100 and 160°C and pressures of 5 to 30 MPa.

12. Process for preparing isophoronediamine according to at least one of the preceding claims, characterized in that the imination reaction is effected in the presence of at least one imination catalyst.

13. Process for preparing isophoronediamine according to at least one of the preceding claims, characterized in that the imination of isophoronenitrile with liquid ammonia is conducted without addition of further solvent.

14. Process for preparing isophoronediamine according to at least one of the preceding claims, characterized in that between 1 and 500 mol, preferably 5 and 200 mol, more preferably between 5 and 100 mol, of ammonia is used per mole of IPN used in the imination stage.

15. Process for preparing isophoronediamine according to at least one of the preceding claims, characterized in that the imination is conducted in the presence of a suspension catalyst or fixed bed catalyst, preferably of at least one fixed bed catalyst.

16. Process for preparing isophoronediamine according to at least one of the preceding claims, characterized in that IPN and ammonia in the imination are conducted continuously from the bottom upward through a reaction tube filled with imination catalyst.

17. Process for preparing isophoronediamine according to at least one of the preceding claims, characterized in that the hydrogen required for the hydrogenation is supplied to the reactor either in excess, preferably at up to 10 000 molar equivalents, or in such an amount that the hydrogen consumed by reaction and the portion of the hydrogen which leaves the reactor dissolved in the product stream is replenished.

18. Process for preparing isophoronediamine according to at least one of the preceding claims, characterized in that the hydrogenation is conducted in liquid ammonia as solvent, using between 1 and 500 mol, preferably 5 and 200 mol, more preferably between 5 and 100 mol, of ammonia per mole of IPN.

19. Process for preparing isophoronediamine according to at least one of the preceding claims, characterized in that the hydrogenation catalysts are first conditioned with ammonia before they are used in the hydrogenation.

20. Process for preparing isophoronediamine according to at least one of the preceding claims, characterized in that hydrogenation is effected continuously in fixed bed reactors.

21. Process for preparing isophoronediamine according to at least one of the preceding claims, characterized in that the hydrogenation is conducted continuously in fixed bed reactors which are operated in trickle mode or liquid phase mode.

22. Process for preparing isophoronediamine according to at least one of the preceding claims, characterized in that the reaction mixture leaving the hydrogenation is purified in one or more stages, and the isophoronediamine is obtained.

23. Process for preparing isophoronediamine according to at least one of the preceding claims, characterized in that the reaction mixture leaving the hydrogenation is purified in two steps, with complete or partial removal particularly of hydrogen, inert gases, ammonia, low-boiling impurities and optionally water in one or more distillation columns in a first step, and complete or partial removal of further low-boiling impurities, water and high-boiling impurities in distillation columns in a second step, and the isophoronediamine is obtained.

24. Use of a catalyst for preparation of isophoronediamine, characterized in that A) isophoronenitrile is subjected directly in one stage to aminating hydrogenation to give isophoronediamine in the presence of ammonia, hydrogen, a hydrogenation catalyst and possibly further additions, and in the presence or absence of organic solvents; or B) isophoronenitrile is first converted fully or partly in at least two or more than two stages to isophoronenitrile imine, and this isophoronenitrile imine is subjected to aminating hydrogenation to give isophoronediamine as a pure substance or in a mixture with other components and / or isophoronenitrile, in the presence of at least ammonia, hydrogen and a catalyst, wherein the catalyst has the following properties: I. The catalyst has, after the activation, in its entirety, the following composition in per cent by weight (% by weight), where the proportions add up to 100% by weight, based on the metals present: Cobalt: 55% to 85% by weight Aluminium: 5% to 43.5% by weight Chromium: 0.5% to 3% by weight Nickel: 1% to 7% by weight and II. The catalyst is in the form of irregular particles as a granular material and after activation has particle sizes of 1 to 8 millimetres (mm) measured by screening.