MXPA00001477A - Use of shaped bodies as a catalyst for the production of caprolactam - Google Patents

Abstract

The invention relates to the use of essentially shaped bodies containing a catalytically active oxide as a catalyst comprising no soluble constituent, under the reaction conditions, for the production of cyclic lactams by reacting aminocarboxylic acid nitriles with water in aqueous phase, in a fixed bed reactor. This catalyst is composed of shaped bodies which can be obtained by shaping the oxide into shaped bodies and by treating the oxide with an acid which is hardly soluble, having 0.1 to 30%by weight of the oxide, before or after the shaping process.

Description

USE OF MOLDING BODIES AS CATALYSTS FOR THE MANUFACTURE OF CAPROLACTAMA Description The present invention relates to the use of molding bodies, which contain, substantially, a catalytically active oxide, as a catalyst for the manufacture of cyclic lactams by reaction of aminocarboxylenitriles with water.

The patent registration application (OZ.0050 / 44458) refers to the use of molding bodies, which under the reaction conditions do not contain any soluble components, as catalysts for the manufacture of cyclic lactams by reaction of aminocarboxynitriles with water in the liquid phase in a fixed bed reactor. The catalysts, which may comprise a number of oxides, selenides, tellurides and phosphates, can be obtained, for example, by forming powders of the corresponding compounds in macaroni.

Although, these molding bodies allow to obtain cyclic lactams, but the selectivity and the yield are not entirely satisfactory, especially with short residence times, which allow to obtain a high space / time yield and with this reduce the size of the reactors.

The object of the present invention is the use of molding bodies, which under the reaction conditions do not contain any soluble components, as catalysts for the manufacture of cyclic lactams by reaction of aminocarboxynitriles with water, in the liquid phase in a fixed-bed reactor , whose use is not accompanied by the disadvantages described above.

This object is achieved according to the invention, using for the production of cyclic lactams by reaction of aminocarboxynitriles with water in the liquid phase in a fixed bed reactor, as a catalyst, molding bodies, which contain, substantially, a catalytically active oxide, whose The catalyst does not contain any soluble components under the reaction conditions, the catalyst forming molding bodies obtained by shaping the oxide into molding bodies and treating the oxide before or after shaping with 0.1 to 30% by weight, with respect to the oxide, an acid in which the oxide is poorly soluble.

Preferred variants of the use according to the invention can be derived from the dependent claims.

As starting substances for the use according to the invention, the aminocarboxynitriles are used, preferably those of the general formula I where n and m respectively may have the values 0, 1, 2, 3, 4, 5, 6, 7, 8 and 9 and the sum of n + m amounts to at least 3, preferably at least 4.

Ri and R2 can be, in principle, substituents of any kind, it being necessary to take care only that the desired cyclization reaction is not affected by the substituents. R 1 and R 2 are preferably each independently of the other, alkyl having 1 to 5 carbon atoms or cylcoalkyl groups having 5 to 7 carbon atoms or aryl groups having 6 to 12 carbon atoms.

Especially preferred starting compounds are the aminocarboxynitriles of the general formula H2 - (CH2) m-S N where m has a value of 3, 4, 5 or 6, especially 5. For m = 5, 6-aminocapronitrile is given as starting material.

According to the invention, the above-described aminocarboxynitriles are transformed with water in the liquid phase, using the heterogeneous catalysts, giving cyclic lactams. When aminocarboxinitriles of the formula I are used, the corresponding cyclic lactams of the formula II are obtained where n, m, R1 and R2 have the meanings indicated above. Especially preferred lactams are those, in which n = 0 and m has the value of 4.5 or 6, especially 5 (in the latter case caprolactam is obtained).

The reaction can be carried out in the liquid phase, at temperatures of, generally, 140 to 320 ° C, preferably 160 to 280 ° C; the pressure should generally range from 1 to 250 bar, preferably from 5 to 150 bar, it being necessary to take care that the reaction mixture is substantially liquid under the conditions applied. The residence times vary, generally from 1 to 120, preferably 1 to 90 and especially 1 to 60 min. In some cases, residence times of 1 to 10 min have been shown to be sufficient.

Generally, at least 0.01 mol, preferably 0.1 to 20 and especially 1 to 5 mol of water are used per mole of aminocarboxynitrile.

Advantageously, the aminocarboxinitrile is used in the form of a solution of 1 to 50% by weight, especially 5 to 50% by weight, very preferably 5 to 30% by weight in water (in which case the solvent is at the same time the reaction component). ) or in water / solvent mixtures. As solvents are mentioned, for example, alkanols, such as methanol, ethanol, ne i-propanol, n-, i- and t-butanol and polyols, such as diethylene glycol and tetraethylene glycol, hydrocarbons, such as petrolether, benzene, toluene, xylene, lacatams, such as pyrrolidone or caprolactam or alkyl-substituted lactams, such as N-methylpyrrolidone, N-methylcaprolactam or N-ethylca-prolactam, as well as carboxylic esters, preferably carboxylic acids with 1 to 8 carbon atoms. Ammonia may also be present in the reaction. Of course, organic solvent mixtures can also be used. In some cases mixtures have been found to be advantageous from water and alkanols in the water / alkanol weight ratio of 1-75 / 25-99, preferably 1-50 / 50-99.

In principle, it is also possible to use the aninocarboxinitriles as reactants and at the same time as solvents.

Suitable catalytically active oxides are acidic, amphoteric or basic oxides, preferably aluminum oxide, such as, for example, alpha or gamma-aluminum oxide, tin oxide, zinc oxide, cerium oxide, especially titanium dioxide. amorphous, such as anatase or rutile, as well as their mixtures and phase mixtures.

The aforementioned compounds can be provided with compounds of the first to seventh, especially, second, third or fourth main group of the periodic system, of the first to seventh secondary group of the periodic system, of the elements of the iron or lanthanide or actinide group, as well as of mixtures of such compounds, or contain them.

If appropriate, these catalysts can contain up to 50% respectively of copper, tin, zinc, manganese, iron, cobalt, nickel, ruthenium, palladium, platinum, silver or rhodium.

These catalytically active oxides can be prepared in a manner known per se, for example by hydrolyzes of the organelles, alcoholates, corresponding salts with inorganic or organic acid, and subsequent quenching or calcination, as well as by pyrogenation, and are generally obtained on trade.

According to the invention, the oxides are treated before or after molding with an acid. As acids. Organic acids are suitable, such as oxalic acid, propionic acid, butyric acid, maleic acid, or inorganic acids, such as isopoly acids, heteropolyacids, sulfuric acid or hydrochloric acid. Particularly suitable catalysts are obtained by a treatment with acetic acid, formic acid, nitric acid, especially phosphoric acid or polyphosphoric acid.

Mixtures of the acids can also be used.

The treatment can be carried out in one or several stages, continuously or discontinuously, the same acid or the same or different acid mixtures being used in the individual stages.

It is also possible to treat the oxides before or after the molding in the indicated manner with an acid.

Preferably, the oxides are treated before molding with an acid.

According to the invention, 0.1 to 30, preferably 0.1 to 10, especially 0.1 to 5% by weight of the acid, calculated as pure acid, are used relative to the pyrogenic titanium dioxide. You can mix the acid with a liquid diluent, like. eg, water.

To obtain the catalysts, the oxides without additives can be used. It is also possible to add additives, such as binders, eg saline water of titanium dioxide, salts of the oxides used, titanium salt compounds, hydrolysable titanium compounds, such as titanium alcoholates or aluminum salts, such as pore formers, for example, for example, methylcellulose, carbon fibers, organic polymer fibers, melamine, starch powders, preferably, prior to molding.

The molding bodies can be present in the most varied forms, for example, as balls, tablets, cylinders, hollow cylinders, pellets, granulates or macaroni. Such molding bodies can be manufactured in a known manner, using appropriate molding machines, such as table presses, extrusion molds, rotary granulators, pelletizers or combinations of such machines.

The shaped material, if appropriate after an acid treatment, is advantageously dried, especially at temperatures of 20 to 120 ° C, preferably in an atmosphere of inert gas or air, and then calcined, especially at 400-750 ° C. , preferably in an atmosphere of inert gas or air.

The heterogeneous catalysts are arranged in a fixed bed. The reaction can be carried out in a manner known per se by runoff or exhaustion, especially in a continuous manner, by bringing the reaction mixture into contact with the catalyst bed.

The advantage of the use according to the invention lies in the possibility of carrying out the clinking in a simple manner continuously with high yields and selectivities and short residence times and very high conversions. Since the catalysts used have, according to the observations made to date, a high useful life, an extremely low catalyst consumption is achieved.

Example 1: Obtaining macaroni from pyrogenic titanium dioxide (formic acid) 8350 g of pyrogenic titanium dioxide powder with a rutile / anatase ratio of 80/20 are bonded for three hours with 47 g of 85% formic acid % and 3750 g of water and then shaped in an extruder under a compression pressure of 70 bar in 4 mm macaroni. The macaroni are dried for 16 hours at 120 ° C and then calcined for 3 hours at 500 ° C.

Analytics of macaroni: weight per liter 989 g / 1 water absorption 0.31 ml / g hardness at cutting 25 N surface area 37 m2 / g Example 2: Obtaining macaroni from pyrogenic titanium dioxide (phosphoric acid) 1950 g of precipitated titanium dioxide powder (anatase) are soaked for 3 hours with 60 g of concentrated phosphoric acid and 900 g of water and then shaped in the striker with a compression pressure of 70 bar in 1.5 mm macaroni .

The macaroni. They are dried for 6 hours at 120 ° C and then calcined for 5 hours.

Analytics of macaroni: weight per liter 722 g / 1 water absorption 0.46 ml / g surface 204 m2 / g Example 3: Obtaining macaroni from precipitated titanium dioxide (nitric acid) 11000 g of titanium dioxide powder precipitated (anatase) are kneaded with 420 g of concentrated nitric acid and then formed in an extruder with a compression pressure of 70 bar in 3 mm macaroni. The macaroni is dried for 6 hours at 120 ° C, then for 2 hours at 320 ° C and calcined for 3 hours at 350 ° C.

Analytics of macaroni: weight per liter 919 g / 1 water absorption 0.32 ml / g - hardness at cutting 25 N surface area 105 m2 / g Examples 4 to 16: Transformation of 6-aminocapronitrile into caprolactam In a heated reactor with a content of 25 ml (diameter: 6 mm, length: 800 mm), filled with catalysts 1 to 4 indicated in the table in the form of gravel, a solution of 6-aminocapronitrile is introduced at 80 bar ( ACN) in water and ethanol in the weight ratios indicated in the table. The product stream leaving the ractor is analyzed by gas chromatography. The results are indicated in the table as examples.

The product stream contains together with caprolactam, substantially ethyl e-aminocaproate and e-aminocapronamide. Both products can be cyclized in caprolactam. Additionally, 5 to 8% of caprolactam oligomers can be found which can be separated into caprolactam. rtí iH • s Catalysts 1 to 4 have been prepared according to catalyst examples 1 to 3: Catalyst 1: titanium dioxide precipitated with 3% phosphoric acid formed in 3 mm macaroni and then ground in 1.0-1.5 mm gravel Catalyst 2: precipitated titanium dioxide with 3% phosphoric acid formed in 3 mm macaroni Catalyst 3: pyrogenic titanium dioxide with 3% phosphoric acid formed in 4 mm macaroni and then ground in gravel 1.6 - 2.0 mm Catalyst 4: pyrogenic titanium dioxide with 0.5% formic acid formed in 4 mm macaroni and then ground in gravel 1.6 - 2.0 mm

Claims (8)

Claims
1. Use of molding bodies containing, substantially, a catalytically active oxide, as catalyst, whose catalyst does not contain any soluble components under the reaction conditions, for the manufacture of cyclic lactams by reaction of aminocarboxynitriles with water in the liquid phase in a reactor of fixed bed, the catalyst being composed of molding bodies obtained by shaping the oxide in molding bodies and treating the oxide before or after shaping with 0.1 to 30% by weight, with respect to the oxide, of an acid in which the oxide is poorly soluble.
2. Use of molding bodies according to claim 1, characterized in that the reaction is carried out at a temperature of 140 to 320 ° C.
3. Use of molding bodies according to one of claims 1 to 2, characterized in that aminocarboxynitriles of the formula are used
4. HN (CH2) m C = N where m is 3, 4, 5, 6, 6, 4. Use of molding bodies according to claim 3, characterized in that 6-aminocapronitrile is used as aminocarboxinitrile.
5. 5. Use of molding bodies according to one of claims 1 to 4, characterized in that a 1 to 50% by weight solution of the aminocarboxynitrile in water or in water / organic solvent mixtures is used.
6. 6. Use of mold bodies according to one of claims 1 to 5, characterized in that the catalyst contains as catalytically active oxide, titanium dioxide, aluminum oxide, tin acid, zinc oxide, cerium oxide or mixtures thereof.
7. 7. Use of molding bodies according to one of claims 1 to 3, characterized in that phosphoric acid or polyphosphoric acid is used as the acid.
8. 8. Use of molding bodies according to one of claims 1 to 7, characterized in that nitric acid, acetic acid or formic acid are used as the acid.