KR20120123117A - Catalytic process for the ammoximation of carbonyl compounds - Google Patents

Abstract

The present invention provides a method for preparing an oxime wherein a carbonyl compound is reacted with NH ₃ and H ₂ O _{2 in the} liquid phase in the presence of a catalyst to form a corresponding oxime, the catalyst component being selected from oxides of metals of Groups 5 and 6 And a catalyst component comprising at least 50% by weight of niobium, calculated as oxide. The process according to the invention is suitable for the preparation of many oximes, in particular cyclohexanone oximes.

Description

Catalytic method for rock simulation of carbonyl compounds {CATALYTIC PROCESS FOR THE AMMOXIMATION OF CARBONYL COMPOUNDS}

The present invention relates to a catalytic method of forming an oxime by the dark simulation of a carbonyl compound using a catalyst.

Typically, oximes are important chemical intermediates. A particularly important component in this aspect is cyclohexanone oxime, which is a precursor for ε-caprolactam (monomer for nylon-6). Other important oximes include cyclododecanone oxime, salicylate oxime and acetophenone oxime.

Methods for the darkening of carbonyl compounds in liquid phase using catalysts are known in the art. For example, US Pat. No. 4,745,221 describes a catalytic process for preparing cyclohexanone oxime by reacting cyclohexanone with NH ₃ and H ₂ O ₂ in the liquid phase in the presence of a catalyst comprising titanium-silicalite. do. EP 347926 describes a catalytic process for preparing oximes from carbonyl compounds using a solid composition consisting of silicon, titanium and oxygen, wherein the composition is an amorphous solid. Best results are obtained when the reaction is carried out in t-butanol or cyclohexanol.

There are disadvantages associated with the methods described in these references. First of all, titanium silicalite is a special chemical that requires complex and difficult specific synthetic routes. t-butanol and cyclohexanol are less attractive as solvents from an environmental point of view.

U. S. Patent No. 1082899 uses a catalyst selected from phosphorus tungstic acid, silicon tungstic acid, boron tungstic acid, phosphorus tungsten vanadic acid and phosphorus tungsten molybdate acid to simulate cyclohexanone with ammonia and hydrogen peroxide in the liquid phase. Describe the method. U. S. Patent No. 3,574, 750 describes a process for darksimulating cyclohexanone with ammonia and hydrogen peroxide in a liquid phase using tungstic acid, isopolytungstic acid, heteropolytungstic acid or salts thereof as a catalyst. International Patent Application Publication No. 93/08160 describes a rock simulation reaction using a metal-peroxo catalyst. These catalysts are typically homogeneous catalysts dissolved in the reaction medium in need of recovery.

Thus, there is a need for a method for preparing oximes from carbonyl compounds that is not affected by these disadvantages. The present invention provides such a method. In this way, the catalyst is used without complex and difficult synthesis methods or aftertreatment and also exhibits high activity in the presence of environmentally attractive solvents such as water.

Accordingly, the present invention provides that the carbonyl compound reacts with NH ₃ and H ₂ O _{2 in} the presence of a catalyst in the liquid phase to form a corresponding oxime, wherein the catalyst comprises a catalyst component selected from oxides of metals of groups 5 and 6 And wherein said catalyst component comprises at least 50% by weight of niobium (calculated as oxide).

The use of this type of catalyst has been found to be helpful in processes with high selectivity and high activity, resulting in high yields of oximes. The process uses hydroxylamine to prevent by-products obtained in uncatalyzed methods. The reaction may also be carried out in a liquid medium. The catalyst is a heterogeneous catalyst that is not dissolved in the reaction medium. It can thus be easily separated from the reaction product and recycled if desired.

The catalyst used in the present invention comprises a catalyst component selected from oxides of metals of Groups 5 and 6, the catalyst component comprising at least 50% by weight of niobium, calculated as oxide. The catalyst may comprise other catalyst components, ie oxides of metals of other groups of the periodic table, for example Groups 4 and 7-14. In one embodiment, the total catalyst component present in the catalyst consists of at least 50% by weight, in particular at least 70% by weight, more in particular at least 90% by weight, of oxides of Group 5 and Group 6 metals. In one aspect, the catalyst component consists essentially of oxides of Group 5 and Group 6 metals, wherein the domains consist essentially of the meaning that the other components are present only at the contaminant level.

As noted above, the catalyst component selected from oxides of metals of Groups 5 and 6 comprises at least 50% by weight of niobium, calculated as oxide. If desired, other Group 5 metals such as vanadium may also be present. Among Group 6, the use of chromium, molybdenum and tungsten or a combination thereof is preferred, but the use of tungsten is particularly preferred.

In one aspect, the catalyst component selected from oxides of metals of Groups 5 and 6 comprises at least 70% by weight, preferably at least 80% by weight, more preferably at least 90% by weight of a Group 5 metal component, calculated as oxides. do. In one embodiment, the catalyst component comprises at least 70% by weight, in particular at least 80% by weight, more particularly at least 90% by weight of niobium, calculated as oxide. More particularly, the catalyst component may consist essentially of the Group 5 metal component, more particularly niobia. In one aspect, the catalyst component selected from oxides of metals of Groups 5 and 6 comprises both niobia and vanadia and, in particular, at least 50% by weight, in particular at least 70% by weight, more particularly 90%, calculated as oxides At least% niobium and at most 50% by weight, in particular at most 30% by weight and more particularly at most 10% by weight of vanadium.

The catalyst used in the process according to the invention may have the following physical properties:

The surface area (measured via BET) is usually at least 10 m ² / g, preferably at least 20 m ² / g. In one aspect, the catalyst has a surface area of at least 80 m ² / g. Catalysts with higher surface areas can typically be more active. The upper limit of the surface area is not critical to the present invention. As a typical value, an upper limit of 500 m ² / g can be mentioned.

The pore volume (measured via N ₂ adsorption) is typically at least 0.05 cm ³ / g, preferably at least 0.10 cm ³ / g. If the pore volume is too small, the activity of the catalyst can be reduced. The upper limit of the void volume is not critical to the present invention. As a typical value, an upper limit of 2 cm ³ / g may be mentioned.

The mean pore diameter (measured via N ₂ adsorption) is typically at least 1 nm, preferably at least 2 nm. The range of 3 to 15 nm may be mentioned as being preferred, in particular 4 to 10 nm may be more preferred.

The catalyst can be prepared by methods known in the art. In one embodiment, the catalyst is prepared by a process in which a salt of a suitable metal is used in the calcination step in the presence of oxygen, whereby the formation of the corresponding oxide is caused. The calcination step is usually carried out at a temperature of 300 to 900 ° C, in particular 400 to 800 ° C. In another embodiment, commercially available oxides are used as starting materials. The oxide can be used directly, but it may be desirable to undergo a calcination step, eg, removing contaminants or changing the catalyst form. Suitable calcination conditions typically include calcination in the presence of air, oxygen or an inert gas at temperatures of at least 300 ° C, preferably at least 350 ° C. As the maximum temperature a value of 900 ° C. may be mentioned. Preferably, calcination occurs at a temperature of 350 to 450 ° C. The calcination time is usually not critical and may depend on the calcination temperature. Periods of 10 minutes to 12 hours are usually suitable, with 2 to 5 hours being more preferred.

The catalyst component may or may not be present on the carrier material. Suitable carrier materials are known in the art and include, for example, particles comprising one or more silica, alumina or activated carbon. When the catalyst component is present on the carrier, it may be present in an amount of from 2 to 90% by weight, in particular from 20 to 90% by weight, more particularly from 40 to 90% by weight, calculated as an oxide. The specific amount may depend on the process configuration chosen.

Catalysts containing a carrier material can be prepared by methods known in the art. Suitable methods include combining the precursor for the metal oxide with the carrier material and calcining the material to convert the precursor to the corresponding oxide. Suitable precursors are for example metal salts. For calcination conditions, reference is made to what is stated above. In one aspect, combining the precursor for the metal oxide with the carrier material comprises contacting particles of the carrier material with an impregnation solution containing a metal salt. In another embodiment, the step of combining the precursor for the metal oxide with the carrier material otherwise co-mixes the precursor for the carrier material, for example aluminum trihydrate or aluminum monohydrate, with the metal oxide, or the precursor for the metal oxide. Or mixing, and then the combination undergoes a calcination step to convert the precursor for the carrier material to an oxide. If desired, the shaping step may be performed before the precursor for the carrier material is converted to the oxide, for example by extrusion, tableting, or other means known in the art. It is also possible to prepare the material in powder form.

The carbonyl compound used as starting material in the process according to the invention is a ketone or an aldehyde. Typically, suitable ketones are ketones of formula R 1 -CO-R 2, wherein R 1 and R 2 can be the same or different and are alkyl, aryl, optionally substituted with hydroxyl, alkyl, aryl, cycloalkyl or heterocyclic aryl groups. Selected from cycloalkyl and heterocyclic aryl groups, R 1 and R 2 have 1 to 20 carbon atoms, where R 1 and R 2 can be joined to form a cyclic alkyl or (hetero) aryl compound. In one embodiment, preferred ketones are cyclic alkylketones in which the ring contains 5 to 12 carbon atoms, wherein the ring may be optionally substituted with a C1-C6 alkyl group.

Particularly preferred ketones are cyclopentanone, cyclohexanone, cycloheptanone, cyclooctanone, t-butyl-cyclohexanone and cyclododecanone.

In another embodiment, the preferred ketone is a ketone of the formula R1-CO-R2, wherein R1 and R2 are selected from C1-C6 alkyl and phenyl. Examples of suitable ketones belonging to this group include acetone, methyl-ethyl-ketone, acetophenone and benzophenone.

Typically suitable aldehydes are aldehydes of the formula R3-CHO, wherein R3 is selected from alkyl, aryl, cycloalkyl and heterocyclic aryl groups optionally substituted with hydroxyl, alkyl, aryl, cycloalkyl and heterocyclic aryl groups, and R3 Has 1 to 20 carbon atoms. In a preferred embodiment, R 3 is selected from optionally substituted phenyl and C 1 -C 10 alkyl. Benzaldehyde, p-tolualdehyde and salicyaldehyde may be mentioned as preferred aldehydes.

Preferred oximes which can be prepared using the process according to the invention are the oximes corresponding to the abovementioned preferred ketones and aldehydes. Particularly preferred oximes may be mentioned cyclohexanone oxime, cyclododecanone oxime, salicylate oxime and acetophenone oxime, with cyclohexanone oxime being particularly preferred.

The reaction takes place in the liquid phase. This means that at least the carbonyl compound is in the liquid phase during the reaction. The reaction was typically carried out in the presence of a liquid medium. The liquid medium helps to ensure good contact between the various reactants, for example by providing a solvent for H ₂ O ₂ and NH ₃ . The liquid medium may also help to prevent the formation of byproducts by diluting the reactants. The liquid medium may be selected from water, organic liquids and mixtures thereof. Water is the most suitable reaction medium. Organic liquids can also be used provided that NH ₃ , or, where appropriate, aqueous ammonia can be dissolved in it. The boiling point of the reaction medium should be higher than the desired reaction temperature.

The use of a liquid medium comprising water is preferred for environmental reasons. Particularly preferred is the use of a medium comprising at least 50% by weight, preferably at least 70% by weight, more preferably at least 90% by weight of water.

The reaction was carried out at a temperature selected such that the carbonyl compound and the reaction medium were in the liquid phase. The upper limit is governed by the boiling point of these compounds under reaction conditions. The use of higher reaction temperatures leads to increased reaction rates, but also to increased formation of byproducts. The use of lower reaction temperatures results in increased selectivity, but also reduced reaction rates. In one embodiment, the reaction is carried out at 100 ° C. or lower, in particular at 90 ° C. or lower, more particularly at 80 ° C. or lower. In one embodiment, the reaction is carried out at a temperature of at least 4 ° C, in particular at least 20 ° C, more particularly at least 50 ° C.

The reaction is preferably carried out at atmospheric pressure. Pressures of up to 5 bar can be applied to help increase the concentration of NH _{3 in} the reaction medium.

The molar ratio of carbonyl compound and NH ₃ is usually in the range from 1: 5 to 5: 1, in particular in the range from 1: 2 to 2: 1, more particularly in the range from 1: 1 to 1: 2. The molar ratio of NH ₃ and H ₂ O ₂ is usually in the range from 1: 5 to 5: 1, preferably in the range from 1: 2 to 2: 1. A molar ratio of NH ₃ and H ₂ O ₂ , which is at least 1: 1, more preferably at least 1.5: 1, may be desirable to prevent the occurrence of undesired side reactions.

Selecting a suitable reaction scheme is within the skill of one in the art. The method can be carried out in a batch mode or in a continuous mode.

If the process is a batch process, it is particularly preferred to use from 0.1 to 100 parts by weight, in particular from 1 to 20 parts by weight of the catalyst component (calculated as oxide) per 100 parts of the carbonyl compound. If the process is a continuous process, the liquid space velocity of the carbonyl compound is preferably in the range of 0.1 to 100 kg of carbonyl compound per kg of catalyst component (calculated as oxide). When expressed in moles, the carbonyl compound / catalyst molar ratio is preferably 50: 1 to 2: 1.

The catalyst may be in a fixed bed, for example a trickle bed, an ebullated bed or a fluid bed, or a finely divided form in the reaction medium. The size and shape of the catalyst particles can be selected to be suitable for use in the selected method. In the case of a fixed layer, this typically means a particle diameter in the range of 0.1 to 15 mm. In the case of a finely divided catalyst in the reaction medium, this typically means a diameter of 1 to 1000 μm, preferably 1 to 100 μm. It may be desirable for the catalyst to be finely divided in the reaction medium. It belongs to the category of the skilled person for selecting the appropriate method configuration.

The invention is illustrated by the following examples, without limitation.

Example

The experiment was performed as follows:

1 g of catalyst was brought into a 100 ml volume of reaction vessel. The catalyst was suspended in 25 ml of reaction medium. The reaction medium was maintained at a temperature of 78 ° C. 2 g of carbonyl compound was charged and the whole was continuously stirred with a magnetic stirrer. 2.8 g of 20% aqueous ammonia solution was added. 4.6 g of 30% H ₂ O ₂ aqueous solution was added to the reactor using a syringe pump at a rate of 2 g / hour. Stirring was continued after the addition was complete so that the total reaction time was 3 hours. The heating was stopped and the reactor contents were cooled at the end of the reaction. The product was analyzed by gas chromatography.

Example 1 Rock Simulation of Cyclohexanone—Influence of Catalyst Calcining Temperature

Cyclohexanone was subjected to a rock simulation method as described above. The reaction medium was ethanol. The molar ratio of cyclohexanone: NH ₃ : H ₂ O ₂ was 1: 2: 2. The molar ratio of cyclohexanone: Nb ₂ O ₅ was 5: 1. The catalyst was commercially available niobia, calcined at different temperatures.

The starting material was niobia (Nb ₂ O ₅ ) with a surface area of 123 m ² / g, a pore volume of 0.19 cm ³ / g and an average pore diameter of 5.2 nm.

The starting material was subjected to calcination in air for a period of 4 hours at different temperatures. The calcination temperature and some catalytic properties are shown in Table 1a.

TABLE 1a

The results are shown in Table 1b.

TABLE 1b

Example 2: Rock Simulation of Various Carbonyl Compounds

Ammosimulation methods were performed as described above using different types of carbonyl compounds. The catalyst was niobia calcined at a temperature of 400 ° C. as described above. The reaction medium was ethanol. The molar ratio of cyclohexanone: NH ₃ : H ₂ O ₂ is 1: 2: 2. The molar ratio of cyclohexanone: Nb ₂ O ₅ was 5: 1. The results are shown in Table 2.

[Table 2]

Example 3: Rock Simulation of Cyclohexanone Using Various Reaction Media

The rocksimulation method of cyclohexanone was performed as described above using different types of reaction media. The catalyst was niobia calcined at a temperature of 300 ° C. (Exp. 3.A) or 400 ° C. (Exp. 3.B and 3.C) as described above. The molar ratio of cyclohexanone: NH ₃ : H ₂ O ₂ was 1: 2: 2. The molar ratio of cyclohexanone: Nb ₂ O ₅ was 5: 1. The results are shown in Table 3.

[Table 3]

Claims (14)

A process for preparing an oxime wherein a carbonyl compound is reacted with NH ₃ and H ₂ O _{2 in the} liquid phase to form a corresponding oxime, the catalyst comprising a catalyst component selected from oxides of Group 5 and Group 6 metals, Wherein said catalyst component comprises at least 50% by weight niobium, calculated as oxide. The method of claim 1,
Wherein the catalyst component consists of at least 70% by weight, in particular at least 80% by weight, more in particular at least 90% by weight of oxides of Group 5 and Group 6 metals. The method according to claim 1 or 2,
Wherein the catalyst component comprises at least 70% by weight, in particular at least 80% by weight, more particularly at least 90% by weight, of niobium, calculated as oxide. The method of claim 3, wherein
The process of claim wherein the catalyst component consists essentially of niobia. The method according to any one of claims 1 to 4,
The catalyst has a surface area of at least 80 m 2 / g, a pore volume of at least 0.1 cm ³ / g and an average pore diameter of 3 to 10 nm. 6. The method according to any one of claims 1 to 5,
The carbonyl compound is a ketone of the formula R1-CO-R2, wherein Rl and R2 may be the same or different and are alkyl, aryl, cyclo optionally substituted with a hydroxy, alkyl, aryl, cycloalkyl or heterocyclic aryl group Selected from alkyl and heterocyclic aryl groups, wherein Rl and R2 have 1 to 20 carbon atoms, and wherein Rl and R2 can be linked to form a cyclic alkyl or (hetero) aryl compound. The method according to claim 6,
Ketones are cyclic alkylketones in which the ring contains 5 to 10 carbon atoms and may be optionally substituted with a C1-C6 alkyl group, in particular cyclopentanone, cyclohexanone, cycloheptanone, cyclooctanone, t-butyl -Cyclohexanone or cyclododecanone. The method according to claim 6,
The ketone is selected from ketones of the formula R1-CO-R2, in particular acetone, methyl-ethyl-ketone, acetophenone and benzophenone, wherein R1 and R2 are selected from C1-C6 alkyl and phenyl. 6. The method according to any one of claims 1 to 5,
The carbonyl compound is an aldehyde of the formula R3-CHO, wherein R3 is selected from alkyl, aryl, cycloalkyl and heterocyclic aryl groups optionally substituted with hydroxy, alkyl, aryl, cycloalkyl or heterocyclic aryl groups, And said R <3> has 1 to 20 carbon atoms. The method of claim 9,
R 3 is selected from optionally substituted phenyl and C 1 -C 10 alkyl. 11. The method according to any one of claims 1 to 10,
The reaction is carried out in the presence of a liquid medium, wherein the medium preferably comprises at least 50% by weight, more preferably at least 70% by weight, more preferably at least 90% by weight of water. 12. The method according to any one of claims 1 to 11,
Wherein the reaction is carried out at a temperature of at most 100 ° C, in particular at most 90 ° C, more in particular at most 80 ° C, and at least 4 ° C, in particular at least 20 ° C, more particularly at least 50 ° C. 13. The method according to any one of claims 1 to 12,
The molar ratio of carbonyl compound and NH ₃ is in the range from 1: 5 to 5: 1, in particular 1: 2 to 2: 1, more particularly 1: 1 to 1: 2, and the molar ratio of NH ₃ and H ₂ O ₂ is 1 : 5 to 5: 1, preferably 1: 2 to 2: 1, more preferably 1: 1 or more, even more preferably 1.5: 1 or more. 14. The method according to any one of claims 1 to 13,
In the case of a batch process, it is carried out using 0.1 to 100 parts by weight, in particular 1 to 20 parts by weight of catalyst component per 100 parts of carbonyl compound, calculated as oxide, and in the case of a continuous process, the liquid space velocity of the carbonyl compound is preferably Is in the range of 0.1 to 100 kg of carbonyl compound per kg of catalyst component calculated as oxide.