JP2011036748A - Catalyst for selectively hydrogenating aromatic nitro compound, method for producing and regenerating the catalyst, and method for selectively hydrogenating aromatic nitro compound by using the catalyst - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a catalyst for selectively and economically hydrogenating only a nitro group even when the nitro group, a carbon-carbon double bond, a halogen atom bonded to an aromatic ring, and groups such as an aromatic ketonic carbonyl group, an aromatic carboxylate group, an aromatic amidic carbonyl group and an aromatic nitrile group are present in one and the same compound and to provide a method for selectively hydrogenating an aromatic nitro compound by using such the catalyst. <P>SOLUTION: The catalyst for selectively hydrogenating the aromatic nitro compound is obtained by depositing silver and/or silver oxide on alumina as a silver component and has the deposited silver component of 0.5-3 nm average particle size. There is also provided a method for producing the catalyst. The method for selectively hydrogenating the nitro group of the aromatic nitro compound comprises a step of heating/mixing the aromatic nitro compound, the catalyst, an organic solvent and hydrogen gas. <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

  The present invention relates to a selective hydrogenation catalyst for aromatic nitro compounds, a production method and a regeneration method thereof, and a selective hydrogenation method for aromatic nitrate compounds using the same.

  Various derivatives are obtained by hydrogenation of aromatic nitro compounds. These are raw materials for image quality improvers for inkjet inks, raw materials for gene introduction agents, intermediates for pharmaceuticals and agricultural chemicals, and raw materials for photosensitive polymer compounds. Utilization as a raw material for a functional polymer such as a molding resin composition raw material has been studied. As an example of such an aromatic nitro compound derivative, aminostyrene or the like is known.

  By the way, some aromatic nitro compounds have one or more functional groups that undergo hydrogenation or hydrogenolysis in addition to the nitro group. In such an aromatic nitro compound, it may be required to selectively hydrogenate or hydrocrack only a part of the functional group, and a catalyst suitable for this is also known.

  For example, an aromatic nitro compound having a carbon-carbon double bond in addition to a nitro group as a functional group is relatively easily hydrogenated, but examples of catalysts that selectively reduce the nitro group among these groups. Are known in which a platinum-supported carbon catalyst is modified with hypophosphorous acid and vanadium (Non-patent Document 1), and other catalysts in which gold nanoparticles are supported on titania are known (non-patent document 1). Patent Document 2).

  However, the catalyst described in Non-Patent Document 1 uses a relatively expensive platinum as a catalyst metal, and the catalyst described in Non-Patent Document 2 uses a relatively expensive gold, so There was a problem that the cost of itself increased.

  Furthermore, the catalyst described in Non-Patent Document 1 has a problem that the manufacturing process becomes complicated because a modification step with a phosphorus compound or a vanadium compound is necessary in the preparation stage.

  On the other hand, as a catalyst for selectively hydrogenating or hydrocracking a part of functional groups of an aromatic nitro compound, a catalyst using silica as a support and relatively inexpensive silver as a metal as an active species is also known. (Non-patent Document 3).

  However, according to the tests of the present inventors, the activity of the catalyst of Non-Patent Document 3 decreases as it is used for the hydrogenation reaction, and its regeneration is difficult.

H.-U.Blaser, U. Siegrist, H. Steiner, in Aromatic Nitro Compounds: FineChemicals through Heterogeneous Catalysis, RA Sheldon, H. van. Bekkum, Eds. (Wiley-VCH, Weinheim, Germany, 2001), p. 389 "Science", 2006, 313, 332 A. Corma, P. Serna, "Chem. Commun.", 2005, 5298-5300

  Accordingly, the present invention provides a nitro group and a group such as a carbon-carbon double bond, an aromatic ring-bonded halogen atom, an aromatic ketonic carbonyl group, an aromatic carboxylic acid ester group, an aromatic amido carbonyl group, and an aromatic nitrile group. Are present in the same compound, a catalyst capable of selectively and economically hydrogenating only the nitro group without hydrogenation or hydrogenolysis of the latter group has been found. It is an object of the present invention to provide a method for selective hydrogenation of aromatic nitro compounds using a simple catalyst.

  As a result of intensive investigations to find a catalyst capable of selectively hydrogenating a nitro group bonded to an aromatic ring or a heterocyclic ring of an aromatic nitro compound, the present inventors have determined that a silver component having a specific particle size is alumina. The present inventors have found that the catalyst supported on the catalyst can solve the above-mentioned problems and have completed the present invention.

  That is, the present invention is an aromatic nitro compound characterized in that silver and / or silver oxide is supported on alumina as the silver component, and the average particle size of the supported silver component is 0.5 to 3 nm. Is a selective hydrogenation catalyst.

  The present invention also provides the method for producing a selective hydrogenation catalyst as described above, wherein alumina is impregnated with an aqueous silver salt solution and dried, followed by calcination and reduction treatment in an oxidizing atmosphere.

  Furthermore, the present invention is a method for selectively hydrogenating a nitro group of an aromatic nitro compound, which comprises mixing an aromatic nitro compound, an organic solvent, the selective hydrogenation catalyst, and hydrogen gas under heating conditions.

  According to the functional group selective hydrogenation catalyst and hydrogenation method of the present invention, a nitro group bonded to an aromatic ring or a heterocyclic ring of an aromatic nitro compound can be hydrogenated with high conversion and selectivity. Moreover, even if a carbon-carbon double bond, an aromatic ring bond halogen atom, an aromatic ketonic carbonyl group, an aromatic carboxylic acid ester group, an aromatic amido carbonyl group, or an aromatic nitrile group is present in the same compound. These functional groups are substantially neither hydrogenated nor hydrocracked.

  Moreover, the catalyst of the present invention can be regenerated without going through a complicated process even when the activity of the catalyst is reduced by a certain amount of use, and is highly economical.

  Hereinafter, the present invention will be described in more detail. In the claims and specification of the present application, the following terms are used in the following meanings.

“Aromatic nitro group” A nitro group bonded to an aromatic ring (aromatic hydrocarbon ring) or heterocyclic ring.
“Aromatic ring-bonded halogen atom” A halogen atom bonded to an aromatic ring or a heterocyclic ring.
“Aromatic ketonic carbonyl group” A carbonyl group constituting a ketone, wherein at least one of two carbon atoms to which the carbonyl group is bonded is a member of an aromatic ring or a heterocyclic ring.
“Aromatic carboxylic acid ester group” A carboxylic acid ester group in which the carbon atom to which the carbonyl group constituting the carboxylic acid ester is bonded is a member of an aromatic ring or a heterocyclic ring.
“Aromatic amido carbonyl group” A carbonyl group constituting an amide, wherein the carbon atom to which the carbonyl group is bonded is a member of an aromatic ring or a heterocyclic ring.
“Aromatic nitrile group” A nitrile group (—CN) bonded to an aromatic ring or a heterocyclic ring.

[Body]
Alumina is used as a carrier for the selective hydrogenation catalyst of the aromatic nitro compound of the present invention (hereinafter sometimes abbreviated as “selective hydrogenation catalyst”). The type of alumina used is not particularly limited, but alumina having high heat resistance and a large specific surface area value is preferable. For example, θ alumina and γ alumina are used, and θ alumina is particularly preferable from the viewpoint of heat resistance.

Although there is no particular limitation on the specific surface area of the alumina used as the carrier, preferably ^{30~3000m 2 / g, 50~500m 2 /} g is particularly preferred. If the specific surface area is too small, sintering is likely to occur during the production and regeneration of the catalyst, and the completed catalyst may not exhibit sufficient activity. On the other hand, if the specific surface area value is too large, the dispersibility of the silver component deteriorates, and in this case as well, a catalyst that exhibits sufficient activity may not be obtained.

  Further, the particle diameter of the alumina used is not particularly limited, but the median diameter is preferably in the range of 0.5 to 500 μm, more preferably 5 to 500 μm. Alumina with a particle size that is too small may reduce the pore volume as a whole, and alumina with a small pore volume may cause a decrease in activity as a catalyst, and may further reduce toxicity resistance. . On the other hand, if the particle size is too large, the specific surface area value per mass of the alumina particles becomes small, the dispersibility of the silver component is lowered, and sufficient activity may not be obtained.

[Silver particles]
The silver component that is the active species of the selective hydrogenation catalyst of the present invention is silver and / or silver oxide. The amount of the silver component supported is not particularly limited, but is preferably 1.0 μmol to 5 mmol, particularly preferably 10 μmol to 3 mmol, and most preferably 100 μmol to 2 mmol in terms of silver element per 1 g of the alumina support. The silver equivalent amount of the silver component with respect to alumina when viewed in terms of weight ratio is preferably 10 wt% or less, and particularly preferably 5 wt%. If the amount of the silver component is too small, sufficient activity may not be obtained and the reaction may take time. On the other hand, if the amount of silver is too large, there is no improvement in activity commensurate with the amount used, or silver particles are sintered during the production of the catalyst or during the reaction, and the effective silver surface area in the reaction. May become relatively small, and in this case, sufficient activity may not be obtained.

In the selective hydrogenation catalyst of the present invention, the average particle size of the silver component particles supported on the support is 0.5 to 3 nm, preferably 0.5 to 2 nm. The particle diameter of the supported silver component can be determined by a wide-area X-ray absorption fine structure (EXAFS) or powder X-ray diffraction. Specifically, the X-ray absorption fine structure (XAFS) of the K shell of Ag is measured at room temperature with SPring-8 and BL-01B1, and from there, the Ag-Ag coordination number of EXAFS Can be obtained by estimating the particle diameter from the calculation formula in the following document ^* .
* A. Jentys, Phys. Chem. Chem. Phys., 1999, vol. 1, p. 4059.

  If the silver component particles are too small, the activity of the catalyst may decrease quickly when used in the reaction. On the other hand, if the average particle size is too large, the specific surface area value per mass of the silver particles becomes small, the activity is lowered, and hydrogenation may not be promoted.

  Further, the silver component used in the selective hydrogenation catalyst of the present invention is preferably metallic silver, but it is not always necessary that all of the silver component is metallic silver, even if part of it is present as silver oxide. Good. For example, in the manufacturing method and the regenerating method described later, the reduction treatment is performed after calcination and oxidation, but the silver component is not necessarily all metallic silver. Thus, when silver oxide and metallic silver are mixed, it is needless to say that it is desirable that the content of metallic silver is high, but the metallic silver content can be appropriately set according to the activity required in practice. Good. Hereinafter, in addition to the selective hydrogenation catalyst, there may be referred to simply as a silver catalyst including alumina carrying a silver component as a raw material, but the silver here is not limited to a metal silver only. .

[Production method]
The production of the silver catalyst of the present invention requires, for example, that a silver compound is dissolved in a solvent, alumina as a carrier is introduced into the solution, and the silver compound is adsorbed or impregnated. The silver compound is not particularly limited as long as it is soluble in the solvent used in the catalyst preparation step. For example, silver nitrate, silver acetate, silver perchlorate, bis (2,2′-bipyridine) silver (I) Examples thereof include nitrate, bis (1,10-phananthroline) silver (I) perchlorate, tetrakis (triphenylphosphine) silver (I) nitrate, and the like, among which silver nitrate is particularly preferable. Among the above silver compounds, when a water-soluble silver compound such as silver nitrate, silver nitrite, silver acetate, or silver perchlorate is used, water can be used as a solvent. Further, as a silver compound, bis (2,2′-bipyridine) silver (I) nitrate, bis (1,10-phananthroline) silver (I) perchlorate and tetrakis (triphenylphosphine) silver (I) nitrate In the case of using a water-insoluble one such as an organic solvent, an organic solvent can be used as a solvent.

  The amount of the silver compound solution impregnated with respect to the carrier is preferably an amount that allows the silver compound solution to spread over the entire carrier, and is preferably adjusted to be approximately 100% or more of the water absorption rate. By impregnating in this way, the silver component can be uniformly supported on the carrier.

As described above, when the carrier is impregnated with the silver compound aqueous solution so that the water absorption rate of the carrier is almost 100%, the concentration of the silver compound aqueous solution is adjusted to a concentration that assumes the supported amount of the silver component. Desirably, the same applies when impregnating a silver compound solution having a water absorption rate of 100% or more. In addition, when impregnating a silver compound solution having a water absorption rate of 100% or more, a solvent evaporation treatment or the like may be appropriately performed so that the silver compound solution is uniformly distributed on the carrier.

  The alumina thus supported on the support by adsorption or impregnation of the silver compound is then dried, calcined and oxidized, and then subjected to a reduction treatment on the silver component that has been oxidized by calcining. A catalyst can be obtained. The conditions for such drying, firing and reduction treatment are not particularly limited, but drying may be performed in the range of 100 to 200 ° C. when water is used as a solvent, and reduced pressure treatment as necessary. Or a dry air stream may be used.

  Moreover, it is preferable that the calcination temperature in manufacture of a silver catalyst is 500-1000 degreeC, and it is more preferable that it is 500-800 degreeC. When the heating temperature is too high, sintering of silver particles starts to occur with the phase transition of alumina, and the activity may be lowered. On the other hand, when the heating temperature is too low, combustion removal of the organic matter adsorbed on the surface becomes incomplete, and it may not be possible to provide the catalyst ability completely.

  Since the selective hydrogenation catalyst of the present invention cannot be obtained in an oxygen-free state (oxygen 0 vol%), the amount of oxygen is preferably about 20 vol%. If the oxygen concentration is too low, Ag in a metallic state is formed at the time of firing, and the particle size after the reduction treatment described later may increase, which is not preferable.

  Furthermore, the silver catalyst thus calcined is further reduced by being added with a reducing agent and heated to become a silver catalyst in which a silver component containing metallic silver is highly dispersed. The silver catalyst of the present invention can be produced by either a wet method or a dry method, but is preferably a dry method. In the case of dry reduction, it is desirable to use a gaseous reducing agent such as gaseous hydrogen. At this time, a gaseous reducing agent such as gaseous hydrogen may be diluted with an inert gas such as nitrogen. Is possible. In particular, by using gaseous hydrogen (hydrogen gas), efficient reduction is performed in the production of the silver catalyst of the present invention, and the amount of the metal component in the silver component can be increased. On the other hand, a liquid reducing agent such as methanol, formaldehyde, formic acid or the like can be used as a reducing agent in the case of reducing by wet.

  It is preferable that the heating temperature in said reduction process is 300-900 degreeC, and 400-800 degreeC is more preferable. If the heating temperature is too low, the reduction may not be sufficiently performed. Conversely, if the heating temperature is too high, the silver component will sinter, the specific surface area value per mass will decrease, the activity will decrease, and hydrogenation will not be promoted. There is.

  The particle diameter of the silver component can also be controlled by the heating temperature in the above oxidation and reduction treatment. For example, when the heating temperature in the reduction treatment is low, the particle size of the silver component can be made relatively small, and when the heating temperature in the reduction treatment is high, the particle size of the silver component can be made relatively large. . In addition, the relationship between the heating temperature and the particle size of silver particles in such a reduction treatment is also affected by changes in the amount of silver component. In many cases, when the amount of the silver component is large, the particle size tends to be large, and when the amount of the silver component is small, the particle size tends to be small.

Preferred conditions for preparing the selective hydrogenation catalyst of the present invention include the following combinations.
-The amount of Ag with respect to alumina is 10 wt% or less.
The firing temperature is 500 to 1000 ° C. (practically 600 to 800 ° C.).
-The oxygen concentration at the time of firing is 20 wt% or more (actually, 20 wt% is sufficient).
・ Reducing atmosphere is hydrogen ・ Reducing temperature is 300 ~ 900 ℃

  As described above, in the selective hydrogenation catalyst of the present invention, since the average particle size of the supported silver component is important, the relationship between the reduction treatment temperature and the average particle size of the silver component or the amount of the silver component is experimentally determined. The selective hydrogenation catalyst having the desired catalytic activity may be prepared based on the relationship between the average particle size of the silver component and the silver component. The reason why the relationship between the heating temperature and the particle size during the reduction as described above is not clear, but the present inventors have verified that the change in the particle size of the silver component due to the heating temperature in the reduction treatment is silica or the like. It was a unique interaction that occurred between the alumina and silver components that was not seen with other carriers.

[Selective hydrogenation reaction]
The selective hydrogenation catalyst of the present invention prepared as described above can be used for selective hydrogenation of a nitro group of an aromatic nitro compound.

  The selective hydrogenation reaction can be carried out by mixing an aromatic nitro compound, the selective hydrogenation catalyst, and hydrogen gas in an organic solvent under heating conditions. The organic solvent used in this selective hydrogenation reaction is not particularly limited, but can be selected from those which can be used as a solvent with little catalyst poisoning and can maintain the addition rate, preferably tetrahydrofuran, methanol, ethanol, toluene. Or a combination thereof.

  The selective hydrogenation method of the present invention is not particularly limited, but the presence of hydrogen is essential. Hydrogen is hydrogen in a free state, and is usually supplied to the reaction system during the reaction or prior to the reaction as hydrogen gas. For example, it may be supplied to the upper gas phase portion of the reaction liquid under stirring or aerated. Hydrogen may be supplied as a mixed gas with an inert gas such as nitrogen.

  Although the pressure of the hydrogen to be supplied is not particularly limited, 0.005 to 30 Ma is preferable as the hydrogen partial pressure, and 0.05 to 10 MPa is particularly preferable. This hydrogenation reaction is usually carried out in a hydrogen gas atmosphere in a wet manner. The reaction temperature is preferably in the temperature range of 120 to 200 ° C.

  Furthermore, the amount of the selective hydrogenation catalyst used in the selective hydrogenation method is 0 in terms of metallic silver based on the silver component supported on the catalyst with respect to the aromatic nitro compound used in the reaction. It is preferably used in an amount in the range of 0.01 to 20 mol%, more preferably in the range of 0.1 to 10 mol%, and in the range of 0.5 to 5 mol%. Is most preferred. If the amount of the selective hydrogenation catalyst used is too small, sufficient activity may not be obtained and the reaction may take time. On the other hand, if the amount of silver in the selective hydrogenation catalyst is too large, the dispersity of the silver component may be reduced to lower the activity, or the activity may not be improved in accordance with the amount used.

  The selective hydrogenation reaction is performed until the nitro group bonded to the aromatic ring or heterocyclic ring of the aromatic nitro compound is hydrogenated to an amino group. Although the reaction time correlates with the amount of the catalyst, it is generally about 0.1 to 48 hours, and preferably about 0.5 to 8 hours.

  By doing so, the nitro group in the aromatic nitro compound is hydrogenated, but other groups such as a carbon-carbon double bond, a halogen atom, a ketonic carbonyl bonded to an aromatic ring or a heterocyclic ring. Groups, carboxylic acid ester groups, amido carbonyl groups, nitrile groups, and the like are not hydrogenated, allowing selective hydrogenation of nitro groups. The selective hydrogenation catalyst used can be easily separated from the solution containing the product by a simple method such as filtration after the completion of the reaction, and can be used repeatedly.

[Catalyst regeneration]
The selective hydrogenation catalyst separated from the reaction system as described above is repeatedly used for the selective hydrogenation reaction again, but is gradually deactivated by repeated use. The main feature of the selective hydrogenation catalyst of the present invention is that it can be regenerated by a relatively simple method even when it is deactivated in this way, and the regenerated catalyst also exhibits almost the same performance as before deactivation. It is possible to do.

  This deactivated selective hydrogenation catalyst is regenerated by washing the catalyst separated from the product-containing solution with a mixed solvent of water and an organic solvent, baking it in an oxidizing atmosphere after drying, and subsequently reducing the catalyst. It is carried out.

  The mixed solvent used for washing is appropriately selected. Specifically, a mixed solvent of distilled water and an organic solvent such as ethanol can be used, and a preferable mixing ratio thereof is a volume ratio of the organic solvent and distilled water. 1: 1 are mentioned.

The temperature for drying after washing is also set as appropriate, but is preferably around 100 ° C.
The calcination temperature of the dried used catalyst is preferably 500 ° C to 1000 ° C, and more preferably 500 ° C to 800 ° C. When the calcination temperature is too high, sintering of silver particles begins to occur with the phase transition of alumina, and the activity may be lowered. Moreover, when the calcination temperature is too low, combustion removal of the organic matter adsorbed on the surface becomes incomplete, and the catalyst cannot be completely regenerated, which is not desirable.

  Since the selective hydrogenation catalyst of the present invention cannot be obtained in an oxygen-free state (oxygen 0 vol%), the amount of oxygen is preferably about 20 vol%. If the oxygen concentration is too low, Ag in a metallic state is formed at the time of firing, and the particle size after the reduction treatment described later may increase, which is not preferable.

  The calcined catalyst is subjected to a reduction treatment because the surface of the silver particles may be oxidized. Although reduction treatment can be selected as appropriate, it can be reduced by using hydrogen gas as a reducing agent at about 300 ° C. for about 5 minutes, or can be reduced under the same conditions as in the above production. .

  That is, the reduction method can be either wet or dry, but is preferably dry. In the case of dry reduction, it is desirable to use a gaseous reducing agent such as gaseous hydrogen. At this time, a gaseous reducing agent such as gaseous hydrogen may be diluted with an inert gas such as nitrogen. Is possible. In particular, by using gaseous hydrogen (hydrogen gas), efficient reduction is performed in the production of the silver catalyst of the present invention, and the amount of the metal component in the silver component can be increased. On the other hand, a liquid reducing agent such as methanol, formaldehyde, formic acid or the like can be used as a reducing agent in the case of reducing by wet.

  It is preferable that the heating temperature in said reduction process is 300-900 degreeC, and 400-800 degreeC is more preferable. If the heating temperature is too low, the reduction may not be sufficiently performed. Conversely, if the heating temperature is too high, the silver component will sinter, the specific surface area value per mass will decrease, the activity will decrease, and hydrogenation will not be promoted. There is.

  In this case as well, the particle diameter of the silver component can be controlled by controlling the heating temperature in the reduction treatment, as in the production of the selective hydrogenation catalyst described above. The particle size of the silver component on the selective hydrogenation catalyst can be obtained through oxidation in the firing or heat reduction using hydrogen as a reducing agent, even if the silver component particles are enlarged in the process of regeneration or in the process of regeneration. Can be finely controlled.

  The selective hydrogenation catalyst regenerated in this way can be used again for the same hydrogenation as described above, and the selective hydrogenation of aromatic nitro compounds can be carried out economically advantageously.

  EXAMPLES Examples, comparative examples, and reference examples of the present invention will be described below to describe the present invention in more detail. However, the present invention is not limited to these examples.

Example 1
Preparation of silver supported catalyst:
The silver catalyst which carry | supported silver of silver content and metal average particle diameter shown in Table 1 by the following method was prepared.

  That is, for catalysts 1 to 5, θ-alumina powder obtained by calcining γ-alumina (alumina “Catapal B” manufactured by Sasol) at 1000 ° C. for 3 hours was used as a carrier, and this was used as a 0.5 M silver nitrate aqueous solution. Soaked in. Then, it dried at 80 degreeC under pressure reduction for 3 hours, and baked at the temperature shown in Table 1 for 3 hours. Furthermore, the catalyst 1 thru | or 5 was obtained as an alumina carrying | support silver catalyst by processing for 10 minutes at the temperature shown in Table 1 under hydrogen stream.

  On the other hand, for catalysts 9 and 10, reference catalysts (JRC-CEO-1 and JRC-MGO-1) provided by the Catalytic Society are used as the supports ceria and magnesia, respectively, and for catalyst 11 the silica as the support. “Q-15” manufactured by Fuji Silysia was used. For catalysts 6 to 8, zirconium oxynitrate dihydrate, tin tetrachloride hexahydrate, and ammonium paratungstate were added to distilled water as zirconia, tin oxide, and tungsten oxide, respectively. Then, a precipitate obtained by adding an aqueous ammonium hydroxide solution (1.0 mol / L) was washed three times with distilled water, and further dried at 100 ° C. was used.

  These carriers were immersed in a 0.5 M aqueous silver nitrate solution. Then, it dried at 80 degreeC under pressure reduction for 3 hours, and baked at the temperature shown in Table 1 for 3 hours. Furthermore, the catalyst 6 thru | or 11 was obtained by processing for 10 minutes at the temperature shown in Table 1 under hydrogen stream.

  The carrier, silver average particle size, silver content, calcination temperature and reduction temperature of each catalyst are summarized in Table 1 above. The average particle size of the supported silver was determined by EXAFS.

Example 1
Hydrogenation reaction of 4-nitrostyrene using a silver supported alumina powder catalyst (catalyst 1) having an average silver particle diameter of 0.7 nm:
In an autoclave with an internal volume of 30 cc, 0.30 g (2 mmol) of 4-nitrostyrene, 0.5 g of catalyst 1 (silver content in the catalyst is 1 wt%, silver usage is 2 mol% with respect to the substrate), and 15 ml of tetrahydrofuran as a solvent. The mixture was further sealed with a stirring bar. After purging the inside of the reactor with hydrogen, the temperature was raised to 160 ° C., the pressure was further increased to 3 MPa, and the reaction was performed for 1 hour. A magnetic stirrer was used for stirring.

  The product was identified by using a gas chromatograph mass spectrometer GCMS-QP5000 manufactured by Shimadzu Corporation, and the yield of the product after the reaction was determined by gas chromatography using n-dodecane as an internal standard substance. As a result, the conversion of 4-nitrostyrene as a raw material was 99%, the selectivity of 4-aminostyrene as a target product was 88%, and the selectivity of 4-ethylaniline as a by-product was 3%. 0.9%.

Example 2
Hydrogenation reaction of 4-nitrostyrene using a silver-supported alumina powder catalyst (catalyst 2) having an average silver particle size of 0.9 nm:
In Example 1, instead of catalyst 1 having an average silver particle size of 0.7 nm, 0.1 g of catalyst 2 having an average silver particle size of 0.9 nm (the silver content in the catalyst was 5 wt%, the amount of silver used was the substrate) 4-nitrostyrene was hydrogenated in the same manner as in Example 1 except that 2 mol%) was used. As a result of the reaction, the conversion rate of 4-nitrostyrene as a raw material was 100%, the selectivity of 4-aminostyrene as a target product was 96%, and the selectivity of 4-ethylaniline as a by-product was It was 3.0%.

Example 3
Hydrogenation of 4-nitrostyrene using a silver supported alumina powder catalyst (catalyst 3) having an average silver particle diameter of 1.1 nm:
In Example 1, instead of the catalyst 1 having a silver average particle diameter of 0.7 nm, 0.1 g of a catalyst 3 having a silver average particle diameter of 1.1 nm (the silver content in the catalyst is 5 wt%, the amount of silver used is the substrate) 4-nitrostyrene was hydrogenated in the same manner as in Example 1 except that 2 mol%) was used. As a result of the reaction, the conversion rate of 4-nitrostyrene as a raw material was 100%, the selectivity of 4-aminostyrene as a target product was 95%, and the selectivity of 4-ethylaniline as a by-product was It was 2.9%.

Comparative Example 1
Hydrogenation reaction of 4-nitrostyrene using a silver supported alumina powder catalyst (catalyst 4) having an average silver particle diameter of 3.4 nm:
In Example 1, instead of catalyst 1 having an average silver particle size of 0.7 nm, 0.1 g of catalyst 4 having an average silver particle size of 3.4 nm (the silver content in the catalyst was 5 wt%, the amount of silver used was the substrate) 4-nitrostyrene was hydrogenated in the same manner as in Example 1 except that 2 mol%) was used. As a result of the reaction, the conversion of 4-nitrostyrene as a raw material was 31%, the selectivity of 4-aminostyrene as a target product was 73%, and the selectivity of 4-ethylaniline as a by-product was It was 2.6%.

Comparative Example 2
Hydrogenation reaction of 4-nitrostyrene using a silver supported alumina powder catalyst (catalyst 5) having an average silver particle diameter of 25 nm:
In Example 1, instead of catalyst 1 having an average silver particle size of 0.7 nm, 0.1 g of catalyst 5 having an average silver particle size of 25 nm (silver content in the catalyst is 5 wt%, the amount of silver used is based on the substrate) 4-Nitrostyrene was hydrogenated in the same manner as in Example 1 except that 2 mol%) was used. As a result of the reaction, the conversion of 4-nitrostyrene as a raw material was 31%, but 4-aminostyrene and 4-ethylaniline as expected hydrogenation products were not produced at all.

Comparative Example 3
Silver supported tungsten oxide powder catalyst (catalyst 6) having an average silver particle diameter of 2.6 nm
Hydrogenation of 4-nitrostyrene using
In Example 1, instead of the silver-supported alumina powder catalyst (catalyst 1) having an average silver particle diameter of 0.7 nm, 0.1 g of catalyst 6 having an average silver particle diameter of 2.6 nm (the silver content in the catalyst is 5 wt. %, The amount of silver used was 2 mol% based on the substrate), and 4-nitrostyrene was hydrogenated in the same manner as in Example 1. As a result of the reaction, the conversion rate of 4-nitrostyrene as a raw material was 11%, the selectivity of 4-aminostyrene as a target product was 98%, and the selectivity of 4-ethylaniline as a by-product was 0%.

Comparative Example 4
Hydrogenation reaction of 4-nitrostyrene using a silver-supported tin oxide powder catalyst (catalyst 7) having an average silver particle diameter of 2.4 nm:
In Example 1, in place of the silver supported alumina powder catalyst (catalyst 1) having a silver average particle diameter of 0.7 nm, 0.1 g of catalyst having a silver average particle diameter of 2.4 nm (silver content in the catalyst of 5 wt. %, The amount of silver used was 2 mol% based on the substrate), and 4-nitrostyrene was hydrogenated in the same manner as in Example 1. As a result of the reaction, the conversion of 4-nitrostyrene as a raw material was 3%, the selectivity of 4-aminostyrene as a target product was 79%, and the selectivity of 4-ethylaniline as a by-product was 0%.

Comparative Example 5
Hydrogenation of 4-nitrostyrene using a silver-supported zirconia powder catalyst (catalyst 8) having an average silver particle diameter of 1.6 nm:
In Example 1, in place of the silver-supported alumina powder catalyst (catalyst 1) having a silver average particle diameter of 0.7 nm, 0.1 g of catalyst having a silver average particle diameter of 1.6 nm (silver content in the catalyst of 5 wt. %, The amount of silver used was 2 mol% based on the substrate), and 4-nitrostyrene was hydrogenated in the same manner as in Example 1. As a result of the reaction, the conversion of 4-nitrostyrene as a raw material was 61%, the selectivity of 4-aminostyrene as a target product was 73%, and the selectivity of 4-ethylaniline as a by-product was It was 3.0%.

Comparative Example 6
Hydrogenation reaction of 4-nitrostyrene using silver-supported ceria powder catalyst (catalyst 9) having an average silver particle size of 0.9 nm:
In Example 1, instead of the silver-supported alumina powder catalyst (catalyst 1) having an average silver particle diameter of 0.7 nm, 0.1 g of a catalyst having an average silver particle diameter of 0.9 nm (silver content of 5 wt% in the catalyst) %, The amount of silver used was 2 mol% based on the substrate), and 4-nitrostyrene was hydrogenated in the same manner as in Example 1. As a result of the reaction, the conversion rate of 4-nitrostyrene as a raw material was 59%, the selectivity of 4-aminostyrene as a target product was 74%, and the selectivity of 4-ethylaniline as a by-product was 0%.

Comparative Example 7
Hydrogenation of 4-nitrostyrene using a silver supported magnesium oxide powder catalyst (catalyst 10) having an average silver particle diameter of 3.0 nm:
In Example 1, instead of the silver-supported alumina powder catalyst (catalyst 1) having an average silver particle size of 0.7 nm, 0.1 g of a catalyst having an average silver particle size of 3.0 nm (silver content of 5 wt% in the catalyst) %, The amount of silver used was 2 mol% based on the substrate), and 4-nitrostyrene was hydrogenated in the same manner as in Example 1. As a result of the reaction, the conversion of 4-nitrostyrene as a raw material was 3%, the selectivity of 4-aminostyrene as a target product was 21%, and the selectivity of 4-ethylaniline as a by-product was 0%.

Comparative Example 8
4- Using a silver supported silica powder catalyst (catalyst 11) having an average silver particle diameter of 2.4 nm
Nitrostyrene hydrogenation:
In Example 1, in place of the silver-supported alumina powder catalyst (catalyst 1) having an average silver particle diameter of 0.7 nm, 0.1 g of catalyst 11 having an average silver particle diameter of 2.4 nm (the silver content in the catalyst is 5 wt. %, The amount of silver used was 2 mol% based on the substrate), and 4-nitrostyrene was hydrogenated in the same manner as in Example 1. As a result of the reaction, the conversion rate of 4-nitrostyrene as a raw material was 100%, the selectivity of 4-aminostyrene as a target product was 97%, and the selectivity of 4-ethylaniline as a by-product was It was 2.0%.

The results of Examples 1 to 3 and Comparative Examples 1 to 8 are collectively shown in Table 2.

Comparative Example 9
Hydrogenation reaction of 4-nitrostyrene using silver powder:
Example 1 is the same as Example 1 except that silver powder (the amount of silver used is 40 mol% with respect to the substrate) is used instead of the silver-supported alumina powder catalyst (catalyst 1) having an average silver particle size of 0.7 nm. Then, 4-nitrostyrene was hydrogenated. As a result of the reaction, the conversion rate of 4-nitrostyrene as a raw material was 1%, and 4-aminostyrene and 4-ethylaniline as expected hydrogenation products were not produced at all.

Comparative Example 10
Hydrogenation of 4-nitrostyrene using platinum supported alumina powder catalyst:
Platinum nitrate is impregnated with θ-alumina powder, dried at 80 ° C. under reduced pressure for 12 hours, calcined at 500 ° C. for 2 hours, and further treated at 300 ° C. for 0.5 hour in a hydrogen stream to obtain platinum-supported alumina powder. A catalyst was obtained. The platinum particle diameter was determined by a CO pulse adsorption method in CO-containing helium at 25 ° C.

  The platinum-supported alumina powder catalyst (platinum used was 0.04 mol% with respect to the substrate and the platinum average particle diameter was 0.7 nm) obtained in this manner was used as the silver-supported alumina powder catalyst (silver average particle in Example 1). 4-Nitrostyrene was hydrogenated in the same manner except that it was used instead of (diameter: 0.7 nm). As a result of the reaction, the conversion rate of 4-nitrostyrene as a raw material was 100%. The target hydrogenation product 4-aminostyrene was not produced at all, and only 4-ethylaniline was produced with a selectivity of 100%.

  As is clear from the above Examples and Comparative Examples, the catalyst of the present invention has a high conversion rate with respect to the hydrogenation of aromatic nitro compounds, a high selectivity, and a low rate of by-product formation. I understand. The characteristics of the hydrogenation of the aromatic nitro compound by the catalyst of the present invention are not limited to 4-nitrostyrene described in the above examples, but are also exhibited in aromatic nitro compounds having other substituents. Is done. Examples are given below.

Example 4
4′− using silver supported alumina powder catalyst (catalyst 2) having an average silver particle diameter of 0.9 nm
Nitroacetophenone hydrogenation:
In Example 2, 4′-nitroacetophenone was hydrogenated in the same manner as in Example 2 except that 4′-nitroacetophenone was used as a substrate instead of 4-nitrostyrene. As a result of the reaction, the conversion rate of 4′-nitroacetophenone as a raw material was 100%, and the selectivity of 4′-aminoacetophenone as a target product was 97%. By-product 4-ethylaniline was not produced.

Example 5
Hydrogenation of 4-nitrobenzamide using a silver supported alumina powder catalyst (catalyst 2) having an average silver particle diameter of 0.9 nm:
In Example 2, 4-nitrobenzamide was hydrogenated in the same manner as in Example 2 except that 4-nitrobenzamide was used as a substrate instead of 4-nitrostyrene and the reaction time was extended to 20 hours. . As a result of the reaction, the conversion of 4-nitrobenzamide as a raw material was 100%, and the selectivity for 4-aminobenzamide as a target product was 98%. By-product 4-aminobenzylamine was not produced.

The results of Example 4 and Example 5 are shown together in Table 3.

  The catalyst of the present invention can be regenerated by a relatively simple method even when deactivated by successive hydrogenation reactions. Examples are shown below.

Example 6 and Comparative Example 11
Regeneration test of selective hydrogenation catalyst:
As a result of repeating the hydrogenation reaction of 4-nitrostyrene described in Example 2, a silver-supported alumina powder catalyst (catalyst 2) having an average silver particle diameter of 0.9 nm, which showed no activity in both addition rate and yield, The solution containing the product was separated by filtration. This was washed with a mixed solvent of distilled water and ethanol volume ratio of 1: 1, dried at 100 ° C., calcined at 500 ° C., 600 ° C., 700 ° C., and subsequently using hydrogen gas as a reducing agent, The catalyst is regenerated by reducing at 300 ° C. for about 5 minutes, and the 4-nitrostyrene hydrogenation reaction described in Example 2 is performed again. The conversion of 4-nitrostyrene and the selectivity of 4-aminostyrene Was measured (Example 6).

  Similarly, as a result of repeating the hydrogenation reaction of 4-nitrostyrene described in Comparative Example 8, the silver-supported silica powder catalyst (catalyst 11) having an average silver particle diameter of 2.4 nm that showed no activity in both the addition rate and the yield. In the same manner as above, the regeneration treatment was performed, and the hydrogenation reaction of 4-nitrostyrene described in Comparative Example 8 was performed again to measure the conversion of 4-nitrostyrene and the selectivity of 4-aminostyrene (Comparative Example). 11).

The results of Example 6 and Comparative Example 11 are summarized in Table 4.

  As can be seen from Table 4, the catalyst of the present invention exhibits excellent performance even after regeneration.

  On the other hand, the silver-supported silica powder catalyst (catalyst 11) of Comparative Example 11 has a fresh state performance before regeneration that is superior to that of the silver-supported alumina powder catalyst. Could not get back.

Reference example 1
As a result of repeating the hydrogenation reaction, regeneration treatment was performed in the same manner as in Example 6 except that the catalyst 2 and the catalyst 11 that lost activity were set at a calcination temperature of 400 ° C. The catalyst subjected to the regeneration treatment was subjected to a hydrogenation reaction of 4-nitrostyrene in the same manner as in Example 6, and the conversion of 4-nitrostyrene and the selectivity of 4-aminostyrene were measured.

  Similarly, the catalyst having lost its activity was washed with a mixed solvent, and the hydrogenation reaction of 4-nitrostyrene was conducted in the same manner as described above, and the conversion of 4-nitrostyrene and the selectivity of 4-aminostyrene were determined. It was measured. These results are shown in Table 5.

  The excellent results obtained by the selective hydrogenation catalyst of the present invention were obtained by using 3-vinylnitrobenzene, 4-nitrostyrene, 4′-nitroacetophenone and 4-nitrobenzamide of the above examples as aromatic nitro compounds. Even when 1-chloro-2-nitrobenzene, 4′-nitroacetophenone, 4-nitrobenzonitrile and methyl 4-nitrobenzoate are used, the same can be obtained.

  According to the hydrogenation method using the selective hydrogenation catalyst of the present invention, only a nitro group bonded to an aromatic ring or a heterocycle present in an aromatic nitro compound can be hydrogenated with high conversion and selectivity. Other functional groups present in the same compound, such as carbon-carbon double bonds, aromatic ring-bonded halogen atoms, aromatic ketonic carbonyl groups, aromatic carboxylic acid ester groups, aromatic amido carbonyl groups, aromatic Group nitrile groups and the like are not hydrogenated.

  Moreover, the catalyst of the present invention can be regenerated without going through a complicated process even when the activity of the catalyst is reduced by a certain amount of use, and is highly economical.

Therefore, the hydrogenation method of the present invention is industrially extremely valuable as a method for selectively hydrogenating only the nitro group of an aromatic nitro compound.

Claims (18)

  Selective hydrogenation of an aromatic nitro compound characterized in that silver and / or silver oxide is supported on alumina as a silver component, and the average particle size of the supported silver component is 0.5 to 3 nm. catalyst.   A nitro group bonded to an aromatic ring or a heterocyclic ring of an aromatic nitro compound can be hydrogenated, and a carbon-carbon double bond, a halogen atom, a ketonic carbonyl group, a carboxylic acid ester bonded to the aromatic ring or the heterocyclic ring 2. The selective hydrogenation catalyst according to claim 1, wherein the amide group, the amide group carbonyl group and the nitrile group are not substantially hydrogenated.   The selective hydrogenation catalyst according to claim 1 or 2, wherein the median diameter of alumina is 0.5 to 500 µm. The specific surface area of the alumina, 30~3000m ² / g and a claims 1 to 3 of any one of claim wherein the selective hydrogenation catalyst.   The selective hydrogenation catalyst according to any one of claims 1 to 4, wherein the supported amount of silver component is 1.0 µmol to 5 mmol in terms of silver element per gram of alumina support.   The method for producing a selective hydrogenation catalyst according to any one of claims 1 to 5, wherein the alumina is impregnated with a silver salt solution and dried, followed by calcination and reduction treatment in an oxidizing atmosphere.   The method for producing a selective hydrogenation catalyst according to claim 6, wherein the calcination in an oxidizing atmosphere is performed at a temperature of 500 to 1000 ° C.   The method for producing a selective hydrogenation catalyst according to claim 6 or 7, wherein the reduction treatment is performed at a temperature of 300 to 900 ° C.   The method for producing a selective hydrogenation catalyst according to any one of claims 6 to 8, wherein the reduction treatment is performed in the presence of gaseous hydrogen.   The method for producing a selective hydrogenation catalyst according to any one of claims 6 to 8, wherein the reduction treatment is performed in the presence of methanol, formaldehyde or formic acid gas.   The silver salt solution is silver nitrate, silver acetate, silver perchlorate, bis (2,2′-bipyridine) silver (I) nitrate, bis (1,10-phananthroline) silver (I) perchlorate or tetrakis ( The method for producing a selective hydrogenation catalyst according to any one of claims 6 to 10, which is a solution of triphenylphosphine) silver (I) nitrate.   A selective hydrogen of a nitro group of an aromatic nitro compound, wherein an aromatic nitro compound, an organic solvent, the selective hydrogenation catalyst according to any one of claims 1 to 5 and hydrogen gas are mixed under heating. Method.   The method for selectively hydrogenating a nitro group of an aromatic nitro compound according to claim 12, wherein hydrogen gas is supplied at a partial pressure of 0.005 to 30 Ma.   The method for selectively hydrogenating a nitro group of an aromatic nitro compound according to claim 12 or 13, wherein the heating temperature is in the range of 120 to 200 ° C.   The amount of the selective hydrogenation catalyst is in the range of 0.01 to 20 mol% in terms of metallic silver based on the silver component supported on the aromatic nitro compound. A method for selectively hydrogenating a nitro group of an aromatic nitro compound according to any one of the items.   The selective hydrogenation catalyst according to any one of claims 1 to 5, which has been catalytically deactivated, is washed with a solvent containing an organic solvent and water, then calcined in an oxidizing atmosphere, and further subjected to a reduction treatment. A method for regenerating a selective hydrogenation catalyst.   The method for regenerating a selective hydrogenation catalyst according to claim 16, wherein the calcination in an oxidizing atmosphere is performed at a temperature of 500C to 1000C.   The method for regenerating a selective hydrogenation catalyst according to claim 16 or 17, wherein the reduction treatment is performed in a hydrogen atmosphere at a temperature of 300 to 900 ° C.