MXPA99009071A - Procedure for the production of amino dicicloalifati - Google Patents

Abstract

The present invention relates to a low pressure process for the hydrogenation of aromatic amines to give the corresponding symmetric dicycloaliphatic amines in the presence of rhodium catalysts which are optionally modified with Ir, Ru, Os, Pd and / or Pt mixtures of these metals , on modified supports with oxides of Cr, Mo, W, Mn and / or Re or mixtures of these

Description

Procedure for the production of dicycloaliphatic amines Description of the invention: The present invention relates to a low pressure process for the hydrogenation of aromatic amines to give the corresponding symmetrical dicycloaliphatic amines in the presence of rhodium catalysts which are optionally modified with a noble metal of the Ir, Ru series. , Os, Pd or Pt on supports modified with salts or oxides of the metals Cr, Mo, W, Mn and / or Re or mixtures of these salts or oxides.

The catalytic hydrogenation of anilines to give the corresponding symmetrical dicycloaliphatic amines in noble metal catalysts is known. There are few works on the hydrogenation of anilines on contact surfaces of noble metals at low pressure.

In EP-A 0324 983 and EP-A 0324 984 a process is described with basically modified catalysts containing both Ru and Pd. While in EP-A 0 324 983 a considerable pressure is used to obtain only small amounts of dicyclohexylamine, a low pressure process with a high yield of dicyclohexylamine is described in EP-A 0324 984. However, the catalysts REF: 31361 res, with approximately 0.1-0.2 kg of educt per liter of catalyst, have very low loading capacity.

In FR 1,530,477 a low pressure process is described in which the aniline reacts in the Pd catalysts, at temperatures between 175 ° C and 190 ° C in a stream of hydrogen and with large amounts of ammonia. The product contains large amounts of dicyclohexylamine.

EP-A 0560 127 describes a low pressure process in which the aniline reacts in the catalysts with Ru-Pd support. The catalysts have very low loading capacity.

In EP-A 0 208 933, Rh catalysts are described on supports modified with Cr-Mn salts. The catalysts were developed for the dehydrogenation of the previous phases of the o-polyphenol synthesis at elevated temperature.

EP-A 0 535 482 also describes heat-resistant Rh catalysts on supports modified with Cr-Mn salts for the preparation of o-phenylphenol, the contact surfaces, in addition to Rh, containing other noble metals.

Rh catalysts can be used in stationary beds of thermostatted catalysts at low pressures and temperatures between 300 and 400 ° C for dehydrogenation.

In US 5 360 934 a process for the hydrogenation of aromatic amines on a rhodium support, which is arranged on a K-catalyst, is published. - or d-Al203. In US 4 960 941 a process for the hydrogenation of aromatic amines in a rhodium catalyst is also published. In this case the rhodium catalyst is applied on a Ti02 support. In both cases the hydrogenation is carried out in liquid phase under pressure.

There are no known applications for the low pressure hydrogenation of anilines with catalysts containing Rh as a noble metal component, although it has been described in the literature that Rh catalysts for low pressure hydrogenations of the anilines (PN Rylan-der, Catalytic Hydrogenation over Platinum Metals, Academic Press 1967 pages 331-363, PN Rylander, Hydrogenation Methods, Academic Press 1985, page 122-133).

A preconceived idea against the development of an Rh catalyst for the production of dicyclohexylamines at low pressure came from a work published a few years ago for the gas phase hydrogenation of Rh aniline on? -Al203. At 1 atm and 200 ° C higher yields of Rh of the catalyst were achieved higher yields, although the selectivity for cyclohexylamine with about 20%, independently of the yield, is very small. The selectivity for dicyclohexylamine decreases from 40 to 20%, even with a higher Rh content and thus with higher yields, so that mostly unwanted products were obtained (V. Vishwanathan, S. Narayanan, J Chem. Soc., Chem. Commun., 1990, 78-80).

The publication states that rhodium catalysts are unsuitable for the industrial hydrogenation of anilines "to give cyclohexylamines and dicyclohexylamines at low pressures in the gas phase.

The present invention has as a task to find a process with low selective pressure and with a loading capacity for the hydrogenation of aromatic amines, preferably of anilines to give dicycloaliphatic amines, preferably dicyclohexylamines.

Surprisingly it was found that Rh-containing contact surfaces on specially treated support materials are powerful catalysts for the realization of a process for the low-pressure hydrogenation of aromatic amines to dicycloaliphatic amines.

The object of the invention is a process for the hydrogenation of aromatic amines to give symmetric dicycloaliphatic amines at pressures between 0.5 and 50 bar with noble metal catalysts on support treated with bases, characterized in that the support is covered with salts of Cr, Mo , W, Mn or Re or mixtures of these salts and because the support thus obtained is activated with Rh as noble metal and optionally with an additional noble metal of the series of Ir, Ru, Os, Pd and / or Pt and because the base it is totally or partially neutralized by final additional impregnation with a soluble acid.

Suitable starting compounds for the process of the invention are aromatic amines, for example those defined in DE 2 502 894 and US 3 636 108. Aniline, alkyl C, -6-aniline and optionally alkylated in the nucleus are diaminobenzoles. C [-C6 alkylated, aminonaphthalenes, C ^ alkylated aminonaphthalenes, alkylated, diaminonaphthalenes and diamino-diphenyl-alkanes C [-C3.

Examples include aniline, N-methylaniline, N-cyclohexylaniline, N-cyclohexylideneaniline, o-, m-, p-toluidine, 2,4-, 2,6-, 2,3-diamino-toluene, diphenylamine, 1- and 2-aminonaphthalene, 1,4-1,5-, 2,5-, 2,6-, 2,7-diamino-naphthalene and the diaminophenylmethane isomers.

Preference may be given, for example, to aniline, N-cyclohexylaniline, o-, m-, p-toluidine, 2,4-, 2,6-, 2,3-diamino-toluene and diphenylamine.

Especially preferred are, for example, aniline, 2,4- and 2,6-diaminotoluene.

The process of the invention for hydrogenating aniline is particularly preferably used.

The anilines may optionally be added together with the monocyclic amine to be recycled to the catalyst in gas form. For an exclusive production of dicyclohexylamines, the monocyclic amine is preferably recycled.

The noble metal catalysts on support for the process of the invention are composed of a support which is covered with a salt of Cr, Mo,, Mn or Re metals or mixtures of said salts. In addition, the supported noble metal catalysts contain Rh as the noble metal and optionally as additional noble metal components a metal of the Ir, Ru, Os, Pd and / or Pt series.

The suitable supports for the noble metal catalysts on the support of the process of the invention are clayey earths, A1203 in the different modifications (or;, K,?,?), Otherwise the usual supports for noble metals such as Ti02, earth of diatomaceous earth, silica gel, BaC03, CaC03, ZnO, MgO, pumice, Zr02, activated carbon and naturally the oxides or hydrous oxides of the metals of the Cr, Mo, Mn and / or Re series, preferably Ti02, BaC03 , MgO,? -Al203 and the hydrated oxides or oxides of metals of the Cr, Mo, Mn and / or Re series, with 7-Al203 being preferred, the oxides or hydrated oxides of metals of the Cr, Mo series, W, Mn and / or Re, being especially preferred? -Al203.

The support can be used as powder or in pieces as balls or as an extruded product, such as rings, wheels, etc., it being also possible to use molded bodies, such as, for example, honeycomb bodies or structures in the form of crossed channels.

Preferably a support with a high BET surface is used. The BET surface should be greater than 50 p / g, preferably between 100 and 500 rtr / g, especially between 200 and 400 m2 / g.

If the support contains oxides or hydrated oxides of metals of the Cr, Mo, W, Mn and / or Re series or mixtures of said hydrated oxides or oxides, the following described modifications of the support material may be renounced before applying the components of noble metal.

If a support free of Cr, Mo,, Mn and / or Re is used, it must first be covered with one or more of these components. This can be done, for example, by impregnating or spraying the support with the appropriate salts of these elements. By drying and then tempering at temperatures of about 200 to 450 ° C the applied salts are converted into compounds adhered on the support. However, the application of the Cr, Mo,, Mn and / or Re compounds can be carried out by co-precipitation of the oxide-hydroxide mixtures on the substrates impregnated with alkali, alkaline earth or ammonium hydroxides and optionally subsequent washing of the soluble parts with water.

Especially preferred is a uniform precipitation by slow release of the base by hydrolysis of a less basic precursor. For this, ureas and urethanes are particularly suitable, urea being particularly suitable.

The support thus treated is dried and then heated between 10 minutes and 10 hours between 200 and 450 ° C, preferably between 250 and 430 ° C, it being possible to gradually raise the temperature within this range.

The appropriate salts of Cr, Mo, W, Mn and / or Re are for example acetate, nitrate, halide or sulfate. Likewise, water-soluble oxides of the highest oxidation levels of Cr, Mo, W, Mn and / or oxides are suitable.

Re.

Pre-treated supports are preferably used with the salts and oxides of Cr and Mn.

After carrying out the optional washing of the soluble compounds and drying and tempering of the modified support with Cr, Mo,, Mn and / or Re, the support is ready to receive the rest of the active substances.

The remaining active substances are Rh and optionally a noble metal of the series of Ir, Ru, Os, Pd and / or Pt, alkaline or alkaline earth metal hydroxides and optionally alkali metal or alkaline earth metal sulfates. The noble metals are applied in the form of solutions of their salts, for example in water. Suitable salts are, for example, halides, preferably chlorides, acetates, nitrates and acetylacetonate. As the alkali metal hydroxide, for example, NaOH or KOH are suitable, such as alkaline earth metal hydroxide, for example Mg (OH) 2.

As the sulphate component, mention may be made, for example, of K2SO4. The compounds may be applied alone or together by impregnation or spraying. A drying process is carried out between each impregnation step.

The application of the alkaline or alkaline earth metal hydroxide can be done before or after the treatment of the support with the noble metal components.

It is preferred first to apply the Rh and then optionally the noble metals for modification, followed by alkali hydroxide and optionally alkali sulfate. Optionally another base impregnation step can be coupled.

After each impregnation with noble metal it is eventually reduced with hydrogen or with another reducing agent. In any case, it is reduced at the end of the last drying, for example with hydrogen at temperatures between 80 and 350 ° C.

After reducing the applied noble metals, the base which is on the noble metal catalyst on the support is totally or partially neutralized by impregnation with soluble acids having a pK, in water at 25 ° C, less than 5.

Suitable acid acids are halo acids, such as hydrochloric acid, organic acids such as acetic acid, formic acid or oxalic acid, inorganic acids, such as, for example, sulfuric acid and phosphoric acid.

For this purpose it is preferred to apply on the noble metal catalyst on support between 0.1 and 10% by weight, preferably between 0.2 and 5% by weight of acid, then drying the contact surface.

The ready-made noble metal catalyst contains between 0.1 and 10% by weight, preferably between 0.3 and 3% by weight, of a noble metal of the series of Rh, Ir, Ru, Os, Pd, and / or Pt, where between 100 and 30%, preferably in re 100 and 70% are Rh. In addition, the noble metal catalyst on support contains between 0.05 and 5% by weight of Cr, Mo, W, Mn and / or Re, with Cr and Mn being preferred. In addition, the noble metal catalyst on support contains between 0.05 and 15% by weight of alkali metal or alkali-iron ions, between 0.1 and 10% by weight of acid anion compounds that are dissolved in water at 25 °. C has a pKh less than 5, as well as possibly between 0.05 and 3% by weight of sulfur in the form of compounds, such as, for example, alkali sulfate, alkaline earth sulphate, preferably potassium sulfate.

Preferably, in the process of the invention, suitable noble metal catalysts on Rh support are used in pieces in the form of a bed. The beds can be adiabatic or can be thermostatted using bundles of tubes crossed or bathed with hot support. A combination of thermostatted beds and adiabatic beds or a series of adiabatic reactors including coupled coolers is also advantageous. The configuration of reactors suitable for beds of this type is state of the art and is known to the specialist.

The reaction can be carried out in such a way that, for example, the aniline and the hydrogen, optionally together with the compounds to be recycled, such as for example hydrogen, ammonia, cyclohexylamine, are heated, the heated mixture is passed over the contact surface, a part of the condensable compounds by cooling and together with the liquid that is previously already present is lowered outward, the remaining gas stream is diverted to be locked out of the inert compounds and the rest is returned by compression to the reaction. The reactor is fed with a mixture of the educt in the form of a gas.

The process of the invention is carried out at temperatures between 50 and 250 ° C, preferably between 100 and 200 ° C, especially between 140 and 180 ° C.

The reaction is carried out in a pressure range between 0.5 and 50 bar, with a preference between 0.7 and 15 bar, especially between 0.9 and 0.8 bar being preferred.

The aromatic amine that will react can do so with hydrogen in a molar ratio between 1/500 and 1/5, with a preference between 1/200 and 1/10, with an especially preferred between 1/150 and 1/40.

Along with the aromatic amines and hydrogen small amounts of ammonia can be passed over the contact surface. The ammonia clearly decreases the reaction rate, decreasing the selectivity for dicyclohexylamine only relatively insignificantly.

The loading of the contact surface in the process of the invention can be between 0.1 and 5 kg, with between 1 and 2 kg of aromatic amine per liter of catalyst and hour being preferred.

The selectivities concerning the dicycloaliphatic amines in the process of the invention are clearly above 95%.

The process of the invention allows aromatic amines to be more selectively converted into dicycloaliphatic amines using less expensive low pressure apparatus.

Examples Example -1 (catalyst preparation) One liter of? -Al203 from the company Rhone-Poulenc (SPH 501, beads, 0 = 4-6 mm, BET surface approximately 350 rr / g) were impregnated with 320 ml of a solution of 30.1 g of MnS04 x H20 , 22.3 g (NH 4) 2 Cr 207 and 164 g of urea. The impregnated support was stirred 1 h at 90 ° C in a saturated water vapor atmosphere. Next, two washes were carried out with 160 ml of water to eliminate the soluble compounds. The support thus obtained was dried and then 30 minutes at 300 ° C in a rotating drum. .3 g of RhCl3 were applied in 360 ml of water by impregnation and the catalyst precursor was then dried at 110 ° C.

Then 320 ml of a solution of 24 g of NaOH and 24 of K2S04 in water were applied.

The contact surface was dried and activated 3.5 h at 160 ° C in a stream of hydrogen.

The contact surface contains 8 g of Rh, 9.2 g of Cr, 9.8 g of Mn, 24 g of NaOH and 24 g of K2S04 per liter.

The contact surface was then dried with a solution of 58 g of H3P04 impregnated in 220 g of water and dried 3 h at 120 ° C in a stream of nitrogen.

Example 2 Table 1 shows that the catalyst of Example 1 is hydrogenated with high loading capacities of approximately 1.6 kg / lxh for long periods of time with a high yield and high selectivity giving dicyclohexylamine from aniline.

The experiment was carried out in an oil-thermostated metal tube with a diameter of the cylindrical catalyst bed of approximately 14 mm. The hydrogen-aniline mixture is fed as a gas.

Tab. 1: Hydrogenation of the aniline, oil temperature 164 ° C, 4 atm, H2 current. Cat: 50 ml contact surface of example 1 The catalyst is especially suitable for a technical production of dicyclohexylamine because it can be regenerated by calcination and reduction with hydrogen. AN = Aniline, CHA = cyclohexylamine, DCA = dicyclohexilamine, UK = unknown components, LS = low boiling compounds (compounds that have a low boiling point, such as benzene).

It is noted that in relation to this date, the best method known to the applicant to carry out the aforementioned invention, is that which is clear from the present description of the invention.

Claims (1)

1. REIMIMDICACICNES Having described the invention as above, the property contained in the following claims is claimed as property: Process for the hydrogenation of aromatic amines to give symmetric dicycloaliphatic amines at pressures of between 0.5 and 50 bar in noble metal catalysts on support treated with bases, characterized in that the support of the noble metal catalysts on support is covered with salts or oxides of Cr, Mo, W, Mn and / or Re or mixtures of these salts or oxides and because the support thus obtained has been activated with Rh as noble metal and optionally with additional noble metal of the series of Ir, Ru, Os, Pd and / or Pt and because the base is finally completely or partially neutralized with an additional impregnation with a soluble acid. Process according to claim 1, characterized in that, the supported noble metal catalyst used is comprised between 0.1 and 10% by weight of noble metal of the series of Rh, Ir, Ru, Os, Pd and / or Pt, which contains between 100 and 30% Rh. Process according to at least one of claims 1 and 2, characterized in that the noble metal catalyst on support additionally contains between 0.05 and 5% by weight of Cr, Mo, W, Mn and / or Re, between 0.05 and 15% by weight of alkali metal or alkaline earth metal ions between 0.1 and 10% by weight of anions of acidic compounds that solubilized in water at 25 ° C have a pj of less than 5 and possibly between 0.05 and 3% by weight of sulfur in the form of compounds. Process according to at least one of claims 1 to 3, characterized in that the carrying capacity of the contact surface is between 0.1 and 5 kg of aromatic amine per liter of noble metal catalyst on support and hour. Process according to at least one of claims 1 to 4, characterized in that the reactor is fed with a mixture of educt in gaseous form.