EP2268396A2

EP2268396A2 - Catalyst for reacting carboxylic acid nitriles

Info

Publication number: EP2268396A2
Application number: EP09734323A
Authority: EP
Inventors: Alexander May; Bernd Vogel; Hermann Siegert; Kurt-Alfred Gaudschun; Thomas Quandt
Original assignee: Evonik Roehm GmbH
Current assignee: Evonik Roehm GmbH
Priority date: 2008-04-22
Filing date: 2009-02-26
Publication date: 2011-01-05
Also published as: DE102008001319A1; JP5377628B2; CA2722334A1; WO2009130075A2; JP2011518039A; CN105148905A; BRPI0910762A2; MX2010011667A; RU2010147293A; RU2496575C2; RU2496575C9; WO2009130075A3; HK1213217A1; KR20110008049A; KR101551994B1; US20110034728A1; TW201004699A; MY158755A; US9289752B2; CN102015099A

Abstract

The invention relates to a catalyst for reacting carboxylic acid nitriles with water, the catalyst comprising at least 60% by weight of manganese dioxide having the empirical formula MnOx, wherein x is in the range of 1.7 to 2.0, and at least one plasticizer. The invention further relates to a method for producing the catalysts mentioned above and to a method for producing carboxylic acid amides by reacting carboxylic acid nitriles with water in the presence of the catalyst according to the invention.

Description

Catalyst for the conversion of carbonitriles

The present invention relates to a catalyst for the preparation of carboxylic acid amides by reaction of carbonitriles with water. Furthermore, the present invention relates to a process for the preparation of these catalysts.

The preparation of carboxylic acid amides by the reaction of carbonitriles with water in the presence of a catalyst comprising manganese dioxide has long been state of the art.

Carboxylic acid amides are often needed in the art as an intermediate. For example, α-hydroxyisobutyric acid amide can be used to prepare methacrylic acid or methacrylic acid esters, in particular methyl methacrylate.

For many documents reference is made to the document DE 1593320. DE 1593320 describes a process for the hydrolysis of nitriles to amides with the aid of manganese dioxide, in which yields of more than 90% were achieved with aliphatic nitriles. This process gives good yields at high speed. However, the disadvantages are the low durability and the mechanical strength of the catalyst. In continuous processes, therefore, the production must be stopped after a short time to replace the catalyst. This process is associated with very high costs, whereby the productivity of the entire process is reduced by the interruption.

The patent JP 09104665 describes the production of active δ-manganese dioxide and defines its activity by the size of the surface. The catalyst described herein shows a very high activity. AI However, there is also the problem of low durability described above. This applies in particular to catalysts which have a particularly large surface area.

To improve the life of the catalysts used for the hydrolysis, many efforts have already been made. For example, EP 379 111 A2 describes the hydrolysis of α-hydroxycarboxylic acid solubles in the presence of manganese dioxide catalysts which have a high content of alkali metals. Due to this high content of alkali metals, these catalysts show a particularly high activity and durability. The hydrolysis can be carried out in particular at a pH in the range from 4 to 8. However, a pH in this range does not lead to a long shelf life of the catalysts without the use of the catalysts specified in more detail in this document (compare EP 379 111 A2, Comparative Example 1). Furthermore, this catalyst does not meet the mechanical requirements that are placed in many systems on these catalysts.

Moreover, EP 545 697 A1 discloses the use of certain heteropolyacids to improve the life of the catalyst. Further improvement in the durability of the catalyst can be achieved through the use of promoters. The compounds are added to the system during the reaction. The pH in the hydrolysis reaction should be less than 4, otherwise the acetone cyanohydrin used will reduce the life of the catalyst. At pH values above 4, the acetone cyanohydrin used can easily disintegrate, which may give rise to by-products which impair the catalyst properties. This document explicitly refers to the teaching of the docu- EP 379 111 A2 (see EP 545 697 A1, page 3, lines 3 to 6).

In addition, the document EP 433 611 A1 describes the use of oxidizing agent for stabilizing the catalysts. Similarly, EP 945 429 A1 describes the use of oxidizing agents to extend catalyst life, with further improvement being achieved by the addition of small amounts of amines. An adjustment of the pH to a predetermined value is not described in any of the documents EP 433 611 A1 and EP 945 429 A1, wherein an improvement in the storage life of catalysts is achieved solely by the use of amines according to the document EP 773 212 A1 can. Therefore, the improvement described in EP 945 429 A1 does not result in an adjustment of the pH but in the combination of the teachings of the documents EP 773 212 A1 and EP 433 611 A1. It should be noted that, in particular, cyanohydrins are generally stabilized by the addition of acids, so that the test data set forth in the examples were probably obtained in acid form. This is evident, for example, from the above-mentioned document EP 379 111 A2. Therefore, it can not be concluded from the experiments set forth in the documents EP 433 611 A1 and EP 945 429 A1 that a certain pH value has been determined.

In addition, brownstone comprehensive catalysts for the preparation of carboxylic acid amides in the document EP 0956 898 A2 are set forth. According to this document, the mechanical strength of the catalysts can be improved by the use of SiO ₂ . In this case, the binder can already be added during the precipitation of MnO ₂ . Indeed shows that the catalysts thus obtained have a property profile that does not meet particularly demanding claims.

For some reactor systems, the catalysts must have a certain shape. EP 0 956 898 A2 describes that the materials used to prepare the catalyst can be extruded. However, following these tests, the devices used for the molding are subjected to an extremely high load, which can lead to premature failure of these devices.

Although the teachings of the previously set forth documents already lead to an improvement in the catalyst properties, there is a continuing need to improve the mechanical stability, in particular the abrasion resistance and the pressure stability at very high activity of the catalyst. A further need for development exists with regard to the improvement of the service life in order to extend the replacement cycles during continuous operation of the installations and to reduce the costs for the replacement of the catalyst. In this context, it should be noted that very large amounts of catalyst are needed.

In view of the prior art, it is an object of the present invention to provide a catalyst for the reaction of carbonitriles with water, which has excellent activity with high mechanical stability. In particular, the catalyst should exhibit high pressure stability and high abrasion resistance. In addition, the catalyst should lead to a particularly high selectivity and a high degree of conversion of the catalyzed reaction. Furthermore, the catalyst or the mass used to prepare the catalyst should be simple and inexpensive. can be formed. Here, the devices used for shaping should be exposed to a relatively low load, so that premature failure of the device can be avoided.

A further object of the present invention can be seen to provide a process for the preparation of carboxylic acid amides, which can be carried out particularly simply, inexpensively and with high yield. A particular problem was in particular to provide a method which ensures a particularly long shelf life of the catalyst at high speed, low energy consumption and low yield losses.

These and other objects which are not explicitly mentioned, but which are readily derivable or deducible from the contexts discussed hereinbelow, are solved by a catalyst having all the features of patent claim 1. Advantageous modifications of the catalysts according to the invention are made in subclaims under protection. A process for the preparation of the catalysts set forth above is the subject of claim 13. With regard to the process for the preparation of carboxylic acid amides, claim 21 provides a solution to the problem underlying this problem.

The present invention accordingly provides a catalyst for reacting carboxylic acid nitriles with water, which is characterized in that the catalyst contains at least 60% by weight of manganese dioxide having a molecular formula MnO _x , where x is in the range from 1.7 to 2.0 and at least one plasticizer. By these measures it is surprisingly possible to provide a catalyst for the reaction of carbonitriles with water, which shows a particularly excellent profile of properties. Thus, a catalyst of the present invention exhibits excellent activity with high mechanical stability. In this case, the catalyst according to the invention leads to a surprisingly high selectivity of the reaction, which can be carried out at a high degree of conversion without increasing side reactions. In addition, the catalyst shows high pressure stability and high abrasion resistance. Furthermore, the catalyst can be easily and inexpensively molded. Here, the devices used for shaping a relatively low load is exposed, so that premature failure of the device can be avoided.

In addition, a catalyst of the present invention enables a surprisingly advantageous process for the preparation of carboxylic acid amides by reacting carbonitriles with water. This reaction is hereinafter also referred to as hydrolysis. One of the surprising advantages is, among other things, that the inventive method ensures a particularly long shelf life of the catalyst at high speed, low energy consumption and low yield losses. As a result, the method can be carried out particularly efficiently and inexpensively, since in a continuous operation of the system only a business interruption to replace the catalyst is rarely necessary.

The catalyst of the present invention comprises at least 60% by weight, preferably at least 80% by weight of manganese dioxide having a molecular formula MnO _x , where x ranges from 1.7 to 2.0. Manganese dioxide exists in several allotropic modifications. They differ greatly in the keep as a catalyst. For pyrolysite (beta-manganese dioxide), the most stable modification, the crystallinity is highest. The crystallinity is less pronounced in the further modifications and goes up to amorphous products, which include, inter alia, alpha- or delta-MnO ₂ . By X-ray diffraction the modifications can be assigned. The chemically and catalytically particularly active forms of manganese dioxide may be partially hydrated and additionally contain hydroxyl groups.

The manganese dioxide-comprising catalyst may comprise further compounds or ions. These include, in particular, alkali metal and / or alkaline earth metal ions which can be introduced into the crystal lattice of MnO ₂ during production or deposited on the surface of MnO ₂ or another component of the catalyst. The preferred alkali metal ions include in particular lithium, sodium and / or potassium ions. The preferred alkaline earth metal ions include in particular calcium and / or magnesium ions. The content of alkali metal and / or alkaline earth metal may preferably be less than 0.6 atoms per atom of manganese. Preferably, the atomic ratio of alkali metal and / or alkaline earth metal to manganese is in the range of 0.01: 1 to 0.5: 1, more preferably in the range of 0.05: 1 to 0.4: 1.

In addition, the catalyst comprising manganese dioxide may contain promoters which may also be introduced into the crystal lattice of MnO ₂ or deposited on the surface of MnO ₂ or another component of the catalyst. Preferred promoters include Ti, Zr, V, Nb, Ta, Cr, Mo, W, Zn, Ga, In, Ge, Sn, and Pt, among others. The content of promoters may preferably be less than 0.3 atoms per atom of manganese. Preferably, the atomic ratio of promoter to manganese is in the Range of 0.001: 1 to 0.2: 1, more preferably in the range of 0.005: 1 to 0.1: 1. Preferably, the catalyst comprising manganese dioxide may comprise from 0.01 to 10% by weight, particularly preferably from 0.1 to 5% by weight, of promoters, this quantity being measured by weight as metal or metal ion.

Preferred manganese dioxide has in the X-ray spectrum (XRD) measured as a powder at least one reflection in the range of 32.0 to 42.0 °. The X-ray spectra can be obtained, for example, with an Xpert per device from Panalytical. This reflection in the range of 32.0 to 42.0 ° particularly preferably has the highest intensity with respect to the further intensities in the range of 20 ° to 65 °, measured as the maximum of the reflection. Particularly preferred manganese dioxide for the preparation of the catalysts shows a low crystallinity, which can be seen inter alia from the X-ray spectrum. The structure of particularly preferred manganese dioxide can be assigned to structural number 44-0141 or 72-1982, which is set forth in ICDD (International Center for Diffraction Data), with manganese dioxide having a structure according to 44-0141 being particularly preferred.

The alkali metal and / or alkaline earth metal ions and the promoters can be added in the preparation of the manganese dioxide or the catalyst, for example in the form of salts. Thus, in particular halides, nitrates, sulfates, carbonates, phosphates and hydroxides of the abovementioned substances can be used, preferably compounds which are soluble in water.

According to a particular aspect of the present invention, the manganese dioxide used to prepare a catalyst according to the invention can be used a specific surface area (BET) in the range from 50 to 1000 m ² per g, more preferably 100 to 300 m ² per g and most preferably 150 to 250 m ² per g, which is determined according to the test specification DIN66131.

The preparation of manganese dioxide, which can be used for the preparation of catalysts according to the invention is known per se and set forth, for example, in EP-AO 379 111, EP-A-956 898, EP-A-0545697 and EP-A-0 433 611. The manganese dioxides to be used according to the invention can preferably be obtained by oxidation of Mn ²⁺ salts, for example MnSO ₄ with permanganates, for example potassium permanganate (compare Biochem.J., 50 p 43 (1951) and J. Chem. P. 2189, 1953). In addition, suitable manganese dioxide can be obtained by electrolytic oxidation of manganese sulfate in aqueous solution.

Manganese dioxide, which can be used according to the invention for the preparation of the catalysts having structures according to 44-0141, can be obtained, for example, by reacting an aqueous solution with 0.71 mol of Mn (II) SO ₄ (in total 15% by weight of Mn ²⁺ in solution), 0.043 mol Zr (IV) (SO ₄ ) ₂ , 0.488 mol conc. Sulfuric acid and 13.24 mol of water at 70 ⁰ C rapidly to a solution of 1, 09 mol KMnO ₄ in 64.5 mol of water. The supernatant solution with the precipitate formed can be heated to 90 ^° C. for 3 hours. The precipitate can subsequently be filtered off, washed four times with one liter of water and dried at 110 ° C. for 12 hours.

In addition to the above-mentioned manganese dioxide, which may optionally be provided with promoters or further additives, a catalyst according to the invention comprises at least one plasticizer. The plasticizer allows a simple and stable shaping of the catalyst according to the invention. The plasticizer is accordingly a compound which improves the plastic ductility of a composition for the preparation of the catalyst. This improves the property of a mass for the preparation of the catalyst according to the invention, after addition of a certain amount of liquid (usually water) and under a certain pressure to be molded (to flow) without breaking, the new form after completion of the molding (after the relaxation) is maintained. This property is achieved, for example, in a sliding of the particles one above the other, which are contained in a mass for the preparation of the catalyst. In order to retain the shape, the applied pressure is initially resisted (the material behaves elastically). When the pressure reaches a certain minimum, the temper value, the mass begins to flow. This type of flow is then called elastic plastic flow, to distinguish it from a viscous flow in liquids. Surprisingly, the use of plasticizers, in particular with the addition of binders or with the use of plasticizers which serve as binders, achieves an improvement in the mechanical properties, for example the abrasion resistance and the compressive strength, of the catalyst. Surprisingly, the high activity and lifetime of the catalyst can be maintained or improved at a high level.

As plasticizer organic compounds can be used, which can be removed preferably at low temperatures of below 400 ⁰ C, preferably below 250 ⁰ C substantially from the catalyst. Preferred plasticizers include silica (SiO ₂ ). Preferably, the plasticizer is a clay mineral, especially a layered silicate, such as dickite, flint, illite, nontronite, hectorite, kaolinite, montmorillonite. Preferred silica-containing plasticizers have a pronounced flake structure and a high fineness. The particle size is preferably less than 1500 nm, preferably less than 700 nm, measured as D95 value, which can be determined, for example, by means of sedimentation. Among other things, the device SediGraph® 5100 from Micromeritics GmbH can be used for this purpose. The use of silica-containing plasticizers can unexpectedly improve the mechanical properties of the catalyst described above.

Preferred plasticizers have a Mohs hardness in the range of 0.5 to 3, more preferably in the range of 1, 5 to 2.

Expediently, a catalyst according to the invention generally comprises from 0.1 to 30% by weight, particularly preferably from 1 to 15% by weight, of plasticizer, without this being intended to restrict it.

Preferably, the catalyst comprises at least one binder. Here, the plasticizer can already serve as a binder. Furthermore, compounds can be used as a binder, which have no plasticizing effect. The binder causes a mechanical stability and compressive strength of the catalyst, which satisfies many requirements. The binder preferably comprises silicon dioxide (SiO ₂ ), particular preference being given to silicates having a specific surface area in the range from 50 to 1200 m ² / g, particularly preferably in the range from 150 to 400 m ² / g. According to a particular aspect of the present invention, the binder may be include various compounds each having SiO ₂ . Particularly preferably, the binder comprises a silicate which is pulverulent in the preparation of the catalyst, particularly preferably skeletal silicates and / or precipitated silicas. Powdered binders preferably have a particle size in the range from 0.2 to 200 μm, particularly preferably in the range from 2 to 50 μm, measured by means of laser diffraction, for example a Malvern Mastersizer® Type 2000.

Furthermore, a SiO ₂ can be used as a binder which is present in the preparation of the catalyst as silica sol. A silica sol to be preferably used for the preparation of the present catalyst preferably has a particle size in the range of 1 to 100 nm, more preferably 5 nm to 75 nm and most preferably in the range of 7 to 10 nm based on the diameter of the particles.

Particular embodiments of inventive catalysts preferably comprise a binder which is present in the preparation of the catalyst as silica sol, and a binder which is pulverulent in the preparation of the catalyst. The weight ratio of silica sol to pulverulent binder may expediently be in the range from 20: 1 to 1: 1, more preferably 15: 1 to 5: 1, these details referring to the solids content of the silica sol.

The proportion of binder in the catalyst is preferably in the range of 0.9 wt .-% to 30 wt .-%, more preferably in the range of 2 wt .-% to 20 wt .-%. Suitably, the total amount of plasticizer and binder in the range of 1 to 30 wt .-%, more preferably in the range of 3 to 20 wt .-%, based on the weight of the catalyst, are. The weight ratio of binder to plasticizer is preferably in the range from 200: 1 to 1:20, particularly preferably from 20: 1 to 5: 1. These data relate in particular to binders which have no or only a slight plasticizing effect. Binders which have a plasticizing effect are attributed to the plasticizers. When using binders or plasticizers which comprise liquids in the preparation of the catalyst, this information refers to the solids content of the binder or plasticizer.

Particularly preferred catalysts include, for example, 1, 0 to 30 wt .-%, in particular 3 to 20 wt .-% SiO ₂ ; 0.1 to 10 wt .-%, in particular 2 to 7 wt .-% K ₂ O; From 0.0 to 5% by weight, in particular from 0.2 to 4% by weight, of ZrO ₂ and from 75 to 99% by weight, in particular from 85 to 98% by weight, of MnO ₂ . The catalyst may comprise further elements as stated above. The composition of the catalysts can be determined by semiquantitative X-ray fluorescence analysis.

The catalyst can preferably be used, for example, in the form of granules or of dried agglomerates, it being possible for the particle size to be frequently dependent on the reaction vessel used. Preferred dried agglomerates show a diameter in the range of 0.5 to 5 mm, more preferably 1 to 3 mm. Appropriate diameters of preferred extrudates are in the range of 0.4 mm to 10 mm, more preferably in the range of 0.8 mm to 6 mm. The length of preferred Extrudates is in the range of 2 mm to 10 mm, more preferably in the range of 3 mm to 5 mm.

The catalyst according to the invention can preferably be prepared by a process in which at least one pulverulent manganese dioxide and at least one powdered plasticizer are mixed to obtain agglomerates.

Preferably, the mixture comprising at least one powdered manganese dioxide and at least one powdered plasticizer can be mixed with a liquid binder to obtain agglomerates.

By liquid binder herein is meant a composition which is in flowable form and is capable, if desired after drying, of binding the components of the catalyst, that is to say improving the mechanical properties, such as compressive and abrasion resistance. The liquid binder preferably comprises water, more preferably at least one silica sol.

Suitably, the agglomerates set forth above can be obtained by the use of an intensive mixer. Intensive mixers are devices that can cause a high energy input into a system. Intensive mixers are known per se. These include, for example, Eirich mixers and Z-arm kneaders. Here, the agglomeration behavior on the binder content, the moisture content, the product fineness and the energy input, in particular the mixer speed, geometry, the degree of filling and the running time can be influenced. Valuable information can be found in particular in the attached examples. Processing the composition in the intensive mixer achieves intensive mixing of all components and pre-compaction of the matter. The precompression is achieved by introducing energy via the movements of the internals present in the intensive mixer, which may for example comprise a turbulizer and a scraper, and the associated shear forces.

The agglomerates prepared in this way can either be used directly as a catalyst after drying as "pellets" or can be subjected to further shaping in a moist state in various manners.Preferably, the size of the dried agglomerates is in the range from 0.5 to 5 mm 1 to 3 mm, this statement referring in particular to spherical agglomerates.

According to a particular aspect of the present invention, the initially obtained agglomerates can be extruded. Surprisingly, it is possible to extrude mixtures for producing a catalyst according to the invention in a particularly simple manner. These mixtures can be converted, for example, by simple drying into a highly active catalyst. Surprisingly, the selectivity and the activity of the catalysts can be improved by extrusion, the increased activity being manifested, for example, by an improved degree of conversion.

Shaping is achieved, for example, using the following machines: Screw extruder handle (type PZVMδb) Granulatformmaschine System Hutt (type GR 1) Ringmatrizenpresse Schlüter (type PP 127) Ring matrix press Sproud Waldron

In addition to a circular cross-section special shapes such as "trilob" (= cloverleaf) or rings are possible.

The drying of the moist aggregates or the extrudates is preferably carried out at a temperature which does not lead to any significant impairment of the catalytic activity of the catalysts. Preferably, the drying temperature is in the range of 10 to 200 ⁰ C, more preferably in the range of 80 to 120 ⁰ C. The drying time may, depending on the drying temperature and the pressure at which the drying takes place, in a wide range. In many cases, a drying time in the range of 10 minutes to 30 hours, more preferably in the range of 20 minutes to 10 hours, is sufficient.

The catalyst of the present invention has excellent mechanical properties.

The catalyst according to the invention enables the efficient production of carboxylic acid amides. In particular, carbonitriles are used which generally have groups of the formula -CN. Carboxylic acid amides comprise at least one group of the formula -CONH ₂ . These compounds are known in the art and described for example in Römpp Chemie Lexikon 2nd edition on CD-ROM.

As starting materials in particular aliphatic or cycloaliphatic carbonitriles, saturated or unsaturated carbonitriles and aromatic and heterocyclic carbonitriles can be used. As Carbonitriles to be used in the starting materials can have one, two or more nitrile groups. Furthermore, it is also possible to use carbonitriles which have heteroatoms, in particular halogen atoms, such as chlorine, bromine, fluorine, oxygen, sulfur and / or nitrogen atoms in the aromatic or aliphatic radical. Particularly suitable carbonitriles preferably comprise from 2 to 100, preferably from 3 to 20, and very preferably from 3 to 5, carbon atoms.

The aliphatic carbonitriles each having a saturated or unsaturated hydrocarbon group include acetonitrile, propionitrile, butyronitrile, isobutyronitrile, valeronitrile, isovaleronitrile, capronitrile, and other saturated mononitriles; Malononitrile, succinonitrile, glutaronitrile, adiponitrile and other saturated dinitriles; α-aminopropionitrile, α-aminomethylthiobutyronitrile, α-aminobutyronitrile, aminoacetonitrile and other α-aminonitriles; Cyanoacetic acid and other nitriles each having a carboxyl group; Amino-3-propionitrile and other β-aminonitriles; Acrylonitrile, methacrylonitrile, allyl cyanide, crotonnitrile or other unsaturated nitriles, and cyclopentanecarbonitrile and cyclohexanecarbonitrile or other alicyclic nitriles.

The aromatic carboxylic acid nitriles include, among others, benzonitrile, o-, m- and p-chlorobenzonitrile, o-, m- and p-fluorobenzonitrile, o-, m- and p-nitrobenzonitrile, p-aminobenzonitrile, 4-cyano-phenol, o -, m- and p-tolunitrile, 2,4-dichlorobenzonitrile, 2,6-dichlorobenzonitrile, 2,6-difluoro-benzonitrile, anisonitrile, a-naphthonitrile, ß-naphthonitrile and other aromatic mononitriles: phthalonitrile, isophthalonitrile, terephthalonitrile and other aromatic dinitriles; Benzyl cyanide, cinnamoyl nitrile, phenylacetonitrile, mandelonitrile, p-hydroxyphenylacetonitrile, p-hydroxyphenylpropionitrile, p-methoxyphenylacetonitrile and other nitriles each having an aralkyl group. The heterocyclic carbonitriles include, in particular, nitrile compounds each having a heterocyclic group containing a 5- or 6-membered ring and having at least one atom selected from the group consisting of a nitrogen atom, an oxygen atom and a sulfur atom a heteroatom, such as 2-

Thiophenecarbonitrile, 2-furonitrile and other nitriles each having a sulfur atom or an oxygen atom as a heteroatom; 2-cyanopyridine, 3-cyanopyridine, 4-cyanopyridine, cyanopyrazine and other nitriles each containing a nitrogen atom as a hetero atom; 5-cyanoindole and other condensed heterocycles; Cyano-piperidine, cyanopiperazine and other hydrogenated heterocyclic nitriles and fused heterocyclic nitriles.

Particularly preferred carboxylic acid nitriles include, in particular, α-hydroxycarboxylic acid nitriles (cyanohydrins), such as, for example, hydroxyacetonitrile, 2-hydroxy-4-methylthio-butyronitrile, α-hydroxy-γ-methylthiobutyronitrile (4-methylthio-2-hydroxybutyronitrile), 2-hydroxypropionitrile (Lactonitrile) and 2-hydroxy-2-methylpropionitrile (acetone cyanohydrin), with acetone cyanohydrin being particularly preferred.

Surprising advantages can be achieved if the reaction mixture comprising manganese dioxide catalyst has a pH in the range of 6.0 to 11, 0, preferably 6.5 to 10.0 and most preferably 8.5 to 9.5. The pH value in this context is defined as the negative decadic logarithm of the activity of the oxonium ions (H ₃ O ⁺ ). This size is therefore dependent inter alia on the temperature, with this size refers to the reaction temperature. For the purposes of the invention it is often sufficient this size with electrical meters (pH meters), where a determination at room temperature rather than the reaction temperature is sufficient for many purposes.

Without the addition of an acid or base, a mixture of the commonly used reactants generally has a pH in the range of 3 to 5.5. Therefore, it is preferable to add a basic substance to adjust the pH of the reaction mixture. For this purpose, preference may be given to using hydroxides or oxides, which are particularly preferably formed by alkaline earth metals or alkali metals. These include, inter alia, Ca (OH) ₂ and Mg (OH) ₂ , MgO, CaO, NaOH, KOH, LiOH or Li ₂ O. Most preferably, LiOH or Li ₂ O is used here. Theoretically, amines can be used to adjust the pH. However, it has been found that the use of amines can have a detrimental effect on the life of the catalyst. Therefore, the proportion of amines, in particular for adjusting the pH in the reaction mixture, is preferably at most 0.1% by weight, more preferably at most 0.01% by weight and most preferably at most 0.001% by weight. , In a particular aspect, no substantial amount of amine is added to adjust the pH of the reaction mixture. In the context of the present invention, ammonia (NH ₃ ) is one of the amines.

It should be noted that the catalyst comprising manganese dioxide has many amphoteric properties, therefore, the pH of the reaction mixture in the reaction is greatly influenced by the type and amount of the catalyst. The expression "the reaction mixture comprising manganese dioxide" shows that the pH is measured without the presence of the catalyst. tion mixture include, for example, solvents, water, carbonitrile, etc.

Surprisingly, it has been found that hydrolysis in the presence of lithium ions leads to a particularly long lifetime of the catalyst comprising manganese dioxide. Accordingly, to further improve the process according to the invention, lithium compounds, in particular water-soluble lithium salts, may be added to the reaction mixture, for example LiCl, LiBr, Li ₂ SO ₄ , LiOH and / or Li ₂ O. The concentration of lithium compounds is preferably in the range from 0.001 to 5 wt .-%, particularly preferably 0.01 wt .-% to 1 wt .-%. The addition may be during or before the hydrolysis reaction.

The hydrolysis of the carbonitrile to the carboxylic acid amide preferably takes place in the presence of an oxidizing agent. Suitable oxidizing agents are well known in the art. These oxidants include, but are not limited to, oxygen-containing gases; Peroxides, for example hydrogen peroxide (H ₂ O ₂ ), sodium peroxide, potassium peroxide, magnesium peroxide, calcium peroxide, barium peroxide, benzoyl peroxide and diacetyl peroxide; Peracids or salts of peracids, for example performic acid, peracetic acid, sodium persulfate, ammonium persulfate and potassium persulfate; and oxo acids or salts of oxoacids, for example periodic acid, potassium periodate, sodium periodate, perchloric acid, potassium perchlorate, sodium perchlorate, potassium chlorate, sodium chlorate, potassium bromate, sodium iodate, iodoiodate, sodium hypochlorite, permanganate salts, for example potassium permanganate, sodium permanganate and lithium permanganate, and salts of chromic acid, for example potassium - chromate, sodium chromate and ammonium chromate. The amount of oxidizing agent used can be in a wide range, with the reactants and products not being oxidized by the oxidizing agent. Therefore, the oxidation sensitivity of these substances may limit the use of the oxidizing agents. The lower limit results from the improvement in the durability of the catalyst to be achieved. Preferably, the molar ratio of oxidant to carbonitrile is in the range of 0.001: 1 to 2: 1, more preferably 0.01: 1 to 1, 5: 1.

These oxidizing agents can be added to the reaction mixture, for example, as a solution and / or as a gas. Particular preference is given to using gases which comprise oxygen as the oxidizing agent. In this case, the gas may contain molecular oxygen (O ₂ ) or ozone (O ₃ ). Furthermore, the gas used as oxidizing agent may contain other gases, in particular inert gases, such as nitrogen or noble gases. In a particular aspect, the gas may preferably comprise from 50 to 98% by volume of inert gas and from 2 to 50% by volume of molecular oxygen (O ₂ ). The preferred gases include in particular air. Furthermore, it is also possible to use a gas which contains less than 20% by volume, in particular less than 10% by volume, of molecular oxygen, these gases generally containing at least 1% by volume, preferably at least 2% by volume, of oxygen ,

Preferably, the amount of oxygen passing through the reaction mixture may be in the range of from 1 to 5,000, more preferably in the range of from 10 to 1000 liters / hour, based on 1 kg of manganese dioxide catalyst.

The water, which is necessary for the hydrolysis of the carbonitrile, can be widely used as a solvent. Preferably, the molar Ratio of water to carbonitrile at least 1, more preferably the molar ratio of water to carbonitrile in the range of 0.5: 1 to 25: 1 and most preferably in the range of 1: 1 to 10: 1.

The water used for the hydrolysis can have a high degree of purity. However, this property is not mandatory. Thus, in addition to fresh water and process water can be used, which includes more or less high amounts of impurities. Accordingly, recycled water can also be used for the hydrolysis.

Furthermore, further constituents may be present in the reaction mixture for the hydrolysis of the carbonitrile. These include u.a. Carbonyl compounds, such as aldehydes and ketones, in particular those which have been used for the preparation of preferably used as carbonitrile cyanohydrins. For example, acetone and / or acetaldehyde may be included in the reaction mixture. This is described for example in US 4018829-A. The purity of the added aldehydes and / or ketones is generally not particularly critical. Accordingly, these substances may contain impurities, in particular alcohols, for example methanol, water and / or α-hydroxyisobutyrate (HIBSM). The amount of carbonyl compounds, in particular acetone and / or acetaldehyde can be used in the reaction mixture in a wide range. Preferably, the carbonyl compound is used in an amount in the range of 0.1-6 moles, preferably 0.1-2 moles per mole of carbonitrile.

The temperature at which the hydrolysis reaction is carried out may generally be in the range of 10-150 ⁰ C, preferably in the range of 20-100 ⁰ C and most preferably in the range of 30-80 ° C. Depending on the reaction temperature, the hydrolysis reaction can be carried out at low or high pressure. Preferably, this reaction is carried out in a pressure range of 0.1 to 10 bar, more preferably 0.5 to 5 bar.

The reaction time of the hydrolysis reaction depends inter alia on the carbonitriles used, the activity of the catalyst and the reaction temperature, which parameter can be within wide limits. The reaction time of the hydrolysis reaction is preferably in the range from 30 seconds to 15 hours, more preferably 15 minutes to 10 hours and most preferably 60 minutes to 5 hours.

In continuous processes, the residence time is preferably 30 seconds to 15 hours, more preferably 15 minutes to 10 hours, and most preferably 60 minutes to 5 hours.

The loading of the catalyst with carbonitrile can be in a wide range. Preference is given to using from 0.01 to 2.0, particularly preferably from 0.05 to 1.0, and very particularly preferably from 0.1 to 0.4 g of carbonitrile per g of catalyst per hour.

The reaction can be carried out, for example, in a fixed bed reactor or in a slurry reactor. If gases are used as the oxidizing agent, in particular so-called trickle bed reactors can be used, which enable good contact of gas, solid and liquid. In trickle bed reactors, the catalyst is arranged in the form of a fixed bed. Here, the trickle bed reactor (Trickle Bed Reactor) can be operated in DC or countercurrent mode. The reaction mixture obtained in this way may generally comprise, in addition to the desired carboxylic acid amide, further constituents, in particular unconverted carbonitrile and optionally used acetone and / or acetaldehyde. Accordingly, the reaction mixture can be purified, wherein, for example, unreacted cyanohydrin can be cleaved in acetone and hydrogen cyanide in order to use these again for the preparation of the cyanohydrin. The same applies to the separated acetone and / or acetaldehyde.

Furthermore, the reaction mixture comprising purified carboxylic acid amide may be purified by ion exchange columns of other ingredients.

In particular, cation exchangers and anion exchangers can be used for this purpose. Suitable ion exchangers for this purpose are known per se. For example, suitable cation exchangers can be obtained by sulfonation of styrene-divinylbenzene copolymers. Basic anion exchangers often comprise quaternary ammonium groups covalently bonded to styrene-divinylbenzene copolymers.

The purification of α-hydroxycarboxamides is i.a. in EP-A-0686623 in more detail.

The carbonitrile used for the hydrolysis can be obtained in any way. In the process according to the invention, the purity of the carbonic acid nitrile, for example cyanohydrin, is generally not critical. DEM according to purified or unpurified carbonitrile can be used for the hydrolysis reaction.

For the preparation of preferably used cyanohydrins, for example, a ketone, in particular acetone, or an aldehyde, for example, acetaldehyde, propanal, butanal can be reacted with hydrocyanic acid to give the corresponding cyanohydrin. Acetone and / or acetaldehyde is particularly preferably reacted in a typical manner using a small amount of alkali or of an amine as the catalyst. The amines used to catalyze this reaction can preferably be used in the form of basic ion exchange resins.

Accordingly, the carbonitrile can preferably be obtained by reacting a ketone or aldehyde with hydrocyanic acid in the presence of a basic catalyst. According to a particular embodiment, an alkaline metal hydroxide can be used as the basic catalyst, the amount of basic catalyst preferably being chosen such that the pH of the mixture used for the hydrolysis reaction is in the range from 6.0 to 11.0, preferably 6 , 5 to 10.0, and most preferably 8.5 to 9.5.

The hydrolysis reaction of the present invention can serve, in particular, as an intermediate step in processes for the preparation of (meth) acrylic acids, in particular acrylic acid (propenoic acid) and methacrylic acid (2-methylpropenoic acid) and of alkyl (meth) acrylates. Accordingly, the present invention also provides a process for producing methyl methacrylate which comprises a hydrolysis step according to a process of the present invention. A process comprising a hydrolysis step of cyanhydride NEN for the production of (meth) acrylic acid and / or alkyl (meth) acrylates are, inter alia, in EP-AO 406 676, EP-AO 407 811, EP-A-0 686 623 and EP-AO 941 984 set forth.

Hereinafter, the present invention will be explained in more detail by way of examples.

example 1

1123.0 g of manganese dioxide (manganese oxide MnO2, type HSA, type 1242239, commercially available from Erachem Comilog), 19.0 g plasticizer A (Actigel 208, commercially available from ITC Minerals & Chemicals) and 19.0 g plasticizer B (Arginotex NX Nanopowders, commercially available from B + M Emergencykämper, Gesellschaft für Bergbau und Mineralstoffe mbH & Co. KG) are dried in a mixer (Eirich, type R 02) at a spinning speed of 1500 min ^-1 and a plate - Rotational speed of 84 min ^"1 intensively mixed for two minutes.

Subsequently, with continued mixing, 445.1 g of aqueous silica sol solution (Köstrosol 0830 A, commercially available from Chemiewerk Bad Köstritz GmbH), containing 29% of SiO ₂ , and 186.7 g of dist. Water is added to this mixture and mixed further until the agglomerates have reached an average size of 1 - 3 mm in diameter.

The wet pellets were dried for 10 h at 100 ⁰ C.

This gives about 1100 g of shaped catalyst body. The composition: Brownstone: 87%%

Plasticizer A: 1, 5% plasticizer B: 1, 5% aqueous silica sol solution: 10% (calculated as SiO ₂ )

The computational composition for the pellets is set forth in Table 1.

Table 1: Composition of the catalyst obtained in Example 1

To determine the mechanical properties of the catalyst, the specific lateral compressive strength was measured. When measuring the specific lateral compressive strength, a test specimen is placed in front of a fixed pressing jaw and with a movable test jaw so long with increasing force pressed until the specimen breaks. The fracture is detected electronically and the force applied until the fracture is given. Here, a constant increase in force of 50 N / s was applied. The measurement was carried out with a TBH 250 measuring instrument from Erweka GmbH, D-63150 Heusenstamm. Further properties of the pellets obtained in Example 1 are shown in Table 2.

Example 2

Example 1 was essentially repeated, but the moist agglomerates were not dried but were processed in a granulation machine System Hutt (type GR 1) into extrudates with a diameter of 1.6 mm. The shaped catalyst was dried at 100 ^° C. for 10 h.

To determine the mechanical properties of the catalyst, the specific lateral compressive strength was measured. Further properties of the extrudate obtained in Example 2 are shown in Table 2.

Example 3

Example 1 was essentially repeated, but the moist agglomerates were not dried but were processed in a ring die press system Schlüter (type PP127) into extrusions with a diameter of 1.4 mm. The shaped catalyst is dried for 10 h at 100 ⁰ C. The shaped catalyst was dried at 100 ° C for 10 hours. To determine the mechanical properties of the catalyst, the specific lateral compressive strength was measured. Further properties of the extrudate obtained in Example 3 are shown in Table 2.

Table 2: Properties of the catalysts obtained in Examples 1 to 3

Example 4

1000.0 g of manganese dioxide (manganese oxide MnO2, type HSA, type 1242239, commercially available from Erachem Comilog), 62.5 g of plasticizer (Actigel 208, commercially available from ITC Minerals & Chemicals) and 62.5 g of powdery binder (type Sipernat 32Or, commercially available from Evonik Degussa GmbH) are mixed thoroughly in a mixer (Eirich, type R 02) at a whirling speed of 1500 min ^-1 and a plate rotation speed of 84 min ^-1 for two minutes.

Subsequently, with continued mixing, 431.0 g of aqueous silica sol solution (Köstrosol 0830 A, commercially available from Chemiewerk Bad Köstritz GmbH), containing 29% SiO ₂ , and 230.0 g dist. Water to this mixture and mixing until the agglomerates have reached a mean size of 1 - 3 mm in diameter.

The wet pellets were dried for 10 h at 100 ⁰ C.

This gives about 1200 g of catalyst-form body. The composition: brownstone: 80%

Plasticizer: 5% powdered binder: 5% aqueous silica sol solution 10% (calculated as SiO ₂ )

The computational composition for the pellets is set forth in Table 3. To determine the mechanical properties of the catalyst, the bulk crushing strength (BCS) was measured. To determine the BCS value, a small cylinder is filled with moldings and subjected from the top to a stamp with increasing pressure again and again over a period of three minutes until the resulting breakage (<= 0.42 mm) amounts to 0 , 5% of the total mass used. The pressure corresponding to this fraction is expressed in megapascals as the "BCS" value. The method is well-known as a "shelling test" and is mainly used for refinery catalysts.

The results obtained of the pellets obtained in Example 4 are shown in Table 4. Table 3: Composition of the catalyst obtained in Example 4

Example 5

Example 4 was essentially repeated, but the wet agglomerates were not dried but were processed in a granulation machine System Hutt (type GR 1) into extrudates with a diameter of 1.6 mm. The shaped catalyst was dried at 100 ^° C. for 10 h.

To determine the mechanical properties of the catalyst, the bulk crushing strength (BCS) was measured. The results obtained of the extrudate obtained in Example 5 are shown in Table 4. Example 6

Example 4 was essentially repeated, but the wet agglomerates were not dried but were processed in a ring die press system Schlüter (type PP127) into extrudates with a diameter of 1.0 mm. The shaped catalyst was dried at 100 ^° C. for 10 h.

To determine the mechanical properties of the catalyst, the bulk crushing strength (BCS) was measured. The results obtained of the extrudate obtained in Example 6 are shown in Table 4

Table 4: Properties of the catalysts obtained in Examples 4 to 6

However, in the values shown in Table 4, it should be noted that large particles tend to have higher values, as smaller particles reach the fraction of fractions more quickly than the final value. Therefore, the extrudate according to Example 5 is much more stable than the pellets according to Example 4. Example 7

1167.0 g of manganese dioxide (manganese oxide MnO 2, type HSA, type 1242239, commercially available from Erachem Comilog), 145.9 g plasticizer (Arginotex NX Nanopowder, commercially available from B + M Nottenkämper, Gesellschaft für Bergbau und Mineralstoffe mbH & Co. KG) are mixed dry in a mixer (Eirich, type R 02) at a swirler rotation speed of 1500 min ^"1 and a plate rotation speed of 84 min ^{" 1} for two minutes.

Subsequently, 487.9 g of aqueous silica sol solution (Köstrosol 0830 A, commercially available from Chemiewerk Bad Köstritz GmbH) containing 29% of SiO ₂ , and 343 g of distilled water are at a vortex rotation speed of 450 rev / min with continued mixing. Water was added to this mixture and mixed further until a uniform composition was obtained.

The wet composition was processed with a screw extruder handle (type PZVMδb) into extrudates with a clover shape. The shaped catalyst was dried at 100 ^° C. for 10 h.

The composition of the catalyst is given by: brownstone: 80%

Plasticizer: 10% aqueous silica sol solution 10% (calculated as SiO ₂ )

The calculated composition for the dried catalyst is set forth in Table 5. Table 5: Composition of the catalyst obtained in Example 7

Example 8

1 167.0 g of manganese dioxide (manganese oxide MnO2, type HSA, type 1242239, commercially available from Erachem Comilog), 145.9 g of plasticizer (Arginotex NX Nanopowder, commercially available from B + M Nottenkämper, Gesellschaft für Bergbau und Mineralstoffe mbH and Co KG) are intensively mixed in a mixer (Eirich, type R 02) at a swirler rotation speed of 1500 min ^-1 and a plate rotation speed of 84 min ^-1 for two minutes. Subsequently, with continued mixing, 487.9 g of aqueous silica sol solution (Köstrosol 0830 A, commercially available from Chemiewerk Bad Köstritz GmbH), containing 29% SiO ₂ , and 137.5 g dist. Water was added to this mixture and mixed further until a uniform composition was obtained.

The moist composition was processed to 0.8 mm cylindrical pins with a ring die press from Schlüter. The shaped catalyst was dried at 100 ^° C. for 10 h.

The composition of the catalyst is given by: brownstone: 80%

Plasticizer: 10% aqueous silica sol solution 10% (calculated as SiO ₂ )

The calculated composition for the dried catalyst is set forth in Table 6.

Table 6: Composition of the catalyst obtained in Example 8

Comparative Example 1

To 1 123.0 g of manganese dioxide (manganese oxide MnO2, type HSA, type 1242239, commercially available from Erachem Comilog) are added with continuous mixing in a mixer (Eirich, type R 02) at a swirling speed of 1500 min ^-1 and a Plate rotation speed of 84 min ^"1 445.1 g of aqueous silica sol solution (Köstrosol 0830 A, commercially available from Chemiewerk Bad Köstritz GmbH), containing 29% SiO ₂ , and 186.7 g dist. Add water and continue mixing until the agglomerates have reached a mean size of 1 - 3 mm in diameter.

An attempt was made to process the wet aggregates with a screw extruder handle (type PZVM8b) into extrudates with a cloverleaf shape. The extrusion begins with very uneven strand exit from the perforated plate. The mass discharge increasingly deteriorates in the form, wherein the starting at about 14 bar pressure in the head in front of the perforated plate rises rapidly to over 30 bar. Along with increasingly deteriorating strand outlet, the discharge largely dried up. The machine becomes this Time off to prevent damage due to overload. After opening the machine, the mass in the pressing head in front of the perforated plate is compacted and firm.

Examples 9 to 11

Example 7 was essentially repeated, but changing the weight proportions of plasticizer and binder. The wet aggregates were processed with a screw extruder handle (type PZVMδb) into extrudates with a diameter of 2 mm. The shaped catalyst was dried at 100 ^° C. for 10 h. The specific lateral compressive strength of the obtained extrudates was investigated. The results obtained are shown in Table 7.

Table 7: Strength of the catalysts obtained in Examples 9 to 11

In the tested area, the hardness increases with the binder content. Example 12

The properties of a catalyst obtained according to Example 1 were investigated in a trickle bed reactor. For this purpose, a mixture of 30 wt .-% acetone cyanohydrin, 40 wt .-% water and 30 wt .-% acetone was reacted at a temperature of 60 ⁰ C and at atmospheric pressure. The loading of the catalyst was about 3 g acetone cyanohydrin per g of catalyst per hour.

Furthermore, about 250 ml of air were used per minute at a pressure of about 1 bar, the amount of catalyst was about 40 g.

The ACH conversion was 19.4%, the HIBA selectivity 95.4%.

Example 13

Example 12 was essentially repeated except that a catalyst obtainable according to Example 2 was used. The ACH conversion was 21%, the HIBA selectivity 97.5%.

Example 14

Example 12 was essentially repeated except that a catalyst obtainable according to Example 3 was used. The ACH degree of conversion was 38.3%, the HIBA selectivity 97.0%.

Example 15 Example 12 was essentially repeated except that a catalyst obtainable according to Example 4 was used. The ACH conversion rate was 32%, the HIBA selectivity 74.1%.

Example 16

Example 12 was essentially repeated except that a catalyst obtainable according to Example 5 was used. The ACH conversion rate was 17%, the HIBA selectivity 97.0%.

Example 17

Example 12 was essentially repeated except that a catalyst obtainable according to Example 6 was used. The ACH conversion rate was 50.1%, the HIBA selectivity 96.1%.

These examples show that the catalysts of the invention have excellent properties. Surprisingly, the shape and the selectivity and the degree of conversion can be improved.

Claims

claims

1. A catalyst for the reaction of carbonitriles with water, characterized in that the catalyst comprises at least 60 wt .-% manganese oxide having a molecular formula MnO _x , wherein x is in the range of 1.7 to 2.0, and at least one plasticizer ,

2. A catalyst according to claim 1, characterized in that the manganese dioxide has a specific surface area in the range of 50 to 1000 m ² up.

3. A catalyst according to claim 1 or 2, characterized in that the catalyst comprising manganese dioxide comprises at least one binder.

4. A catalyst according to any one of the preceding claims, characterized in that the binder comprises SiO ₂ .

5. A catalyst according to any one of the preceding claims, characterized in that the binder is a silicate having a specific surface area in the range of 150 to 400 m ² / g.

6. A catalyst according to any one of the preceding claims, characterized in that the plasticizer is a clay mineral.

7. A catalyst according to any one of the preceding claims, characterized in that the plasticizer has a Mohs hardness in the range of 0.5 to 3.

8. A catalyst according to any one of the preceding claims, characterized in that the catalyst comprises alkali metal and / or alkaline earth metal ions.

9. A catalyst according to any one of the preceding claims, characterized in that the catalyst comprises at least one promoter.

10. A catalyst according to claim 9, characterized in that the promoter is selected from Ti, Zr, V, Nb, Ta, Cr, Mo, W, Zn, Ga, In, Ge, Sn and Pt and mixtures of these elements.

11. Catalyst according to claim 1, characterized in that the catalyst comprises at least 80% by weight of manganese dioxide having a molecular formula MnO _x , where x is in the range from 1.7 to 2.0.

12. A catalyst according to any one of the preceding claims, characterized in that the total amount of plasticizer and binder is 1 to 30 wt .-%, based on the weight of the catalyst sector.

13. A process for the preparation of a catalyst according to any one of the preceding claims 1 to 12, characterized in that mixing at least one powdered manganese dioxide and at least one powdered plasticizer to obtain agglomerates.

14. The method according to claim 13, characterized in that admixing the mixture, comprising at least one powdered manganese dioxide and at least one powdered plasticizer, with a liquid binder.

15. The method according to claim 14, characterized in that the liquid binder comprises at least one silica sol.

16. The method according to any one of claims 13 to 15, characterized in that additionally a powdered binder is used sets.

17. The method according to claim 16, characterized in that the pulverulent binder is a scaffold silicate and / or a precipitated silica.

18. The method according to any one of claims 13 to 17, characterized in that the agglomerates are generated by energy input in an intensive mixer.

19. The method according to any one of claims 13 to 18, characterized in that the agglomerates obtained in step B) have a diameter in the range of 0.5 mm to 5 mm.

20. The method according to any one of claims 13 to 19, characterized in that in step B) obtained agglomerates are extruded.

21. A process for the preparation of carboxylic acid amides by reacting carbonitriles with water, characterized in that the reaction in the presence of a manganese dioxide comprising catalyst according to any one of claims 1 to 12 is performed.

22. The method according to claim 21, characterized in that the catalyst comprising the manganese dioxide given reaction mixture has a pH in the range of 6.0 to 11, 0 and the hydrolysis is carried out in the presence of an oxidizing agent.

23. The method according to claim 21 or 22, characterized in that the carbonitrile is 2-hydroxy-2-methylpropionitrile or 2-hydroxypropionitrile.

24. The method according to any one of claims 21 to 23, characterized in that the hydrolysis reaction is carried out in a trickle bed reactor.