JPH11253801A - Preparation of catalyst for ammoxidation - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain an excellent yield of nitrile by cooling an aq. soln. or aq. suspension containing oxalic acid and niobium compds., separating by filtering to obtain a niobium-contg. liquid, controlling the liquid to have a specified molar ratio of oxalic acid/niobium, and using the liquid as a niobium source liquid. SOLUTION: An aq. soln. or aq. suspension prepared by adding and stirring niobium compds. and oxalic acid in water is cooled and separated by filtering to obtain a niobium-contg. liquid. The cooling process is easily carried out with water, and the separating process is easily carried out by decantation or filtering. The obtd. niobium-contg. liquid is controlled to have 2 to 4 molar ratio of oxalic acid/niobium. The controlling process is carried out by adding a niobium compd. selected form niobic acid or niobium hydrogen oxalate, or oxalic acid to the niobium-contg. liquid. Generally, a niobium-contg. liquid having 2 to 4 molar ratio of oxalic acid/niobium can be directly obtd. by properly controlling the molar ratio of oxalic acid/niobium, niobium concn. and cooling temp. in the preparation process.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a method for preparing a catalyst containing niobium for use in a gas-phase catalytic ammoxidation reaction of an alkane and a method for producing an unsaturated nitrile in the presence of the catalyst.

[0002]

2. Description of the Related Art In recent years, in producing unsaturated nitriles, attention has been paid to a method for producing a corresponding unsaturated nitrile by an ammoxidation reaction in which an alkane is brought into gaseous contact with ammonia and oxygen instead of an alkene.

[0003] Various catalysts containing niobium have been proposed for use in this reaction. For example, Mo-V-Nb-Te-containing oxide catalysts are disclosed in JP-A-2-257 and JP-A-5-1482.
12, JP-A-5-208136, JP-A-6-2
85372, JP-A-7-144132, JP-A-7-289907, JP-A-8-57319, and JP-A-8-141401. In these publications, niobium ammonium oxalate, niobate, NbCl ₃ , NbCl ₅ , Nb ₂ (C ₂ O ₄ ) are used as raw materials for niobium in the preparation of an oxide catalyst.
_{5, Nb 2 O 5, Nb} (OC 2 H 5) 5 and the like are used.

[0004] Mo-V-Nb-Sb-containing oxide catalysts are disclosed in JP-A-63-295545, JP-A-2-95439, JP-A-5-213848 and JP-A-9-15.
No. 7241 and the like. In these publications, niobium ammonium oxalate or Nb ₂ O ₅ is used. Catalysts prepared using these niobium compounds in the form of aqueous solutions or suspensions have not only poor nitrile yields, but also poor reproducibility. In particular, a niobium-containing catalyst supported on silica to impart abrasion resistance for use in a fluidized bed reaction has a problem that the yield decreases as the silica content increases.

[0005]

SUMMARY OF THE INVENTION An object of the present invention is to provide a method for preparing a niobium-containing catalyst having an excellent nitrile yield, particularly a catalyst containing niobium supported on silica.

Means for Solving the Problems In order to solve this problem, the present inventors have made intensive studies on a method for preparing a catalyst containing niobium used for ammoxidation of alkanes. As a result, an aqueous solution containing oxalic acid and a niobium compound, The present inventors have found that a catalyst prepared by using a niobium-containing liquid obtained by filtering an aqueous suspension and then filtering the resulting suspension as a raw material liquid gives an excellent nitrile yield, leading to the present invention.

That is, the present invention provides (1) a method for preparing a niobium-containing catalyst used in an ammoxidation reaction of an alkane,
After cooling an aqueous solution or aqueous suspension containing oxalic acid and a niobium compound, the niobium-containing liquid obtained by filtration is adjusted so that the molar ratio of oxalic acid / niobium becomes 2 to 4, and used as a niobium raw material liquid. A method for preparing a niobium-containing catalyst, comprising: (2) The method for preparing a catalyst according to (1), wherein the niobium compound is at least one or more selected from niobate and niobium hydrogen oxalate. (3) The method for preparing a catalyst according to (1) or (2), wherein the catalyst is represented by the following general composition formula.

[0007] _{Mo 1 V a Nb b X c} Z d O n (1) ( wherein, at least one element component X is selected from Te and Sb, component Z is W, Cr, Ta, Ti, Z
r, Hf, Mn, Re, Fe, Ru, Co, Rh, N
i, Pd, Pt, Ag, Zn, B, Al, Ga, In,
Ge, Sn, Pb, P, Bi, Y, at least one element selected from rare earth elements and alkaline earth metals, a, b, c, d, and n each represent an atomic ratio per Mo atom; 1 ≦ a ≦ 1, 0.01 ≦ b ≦ 1, 0.0
1 ≦ c ≦ 1, 0 ≦ d ≦ 0.1, and n is a number determined by the oxidation state of the constituent metal. (4) The method for preparing a catalyst according to any one of (1) to (3), wherein the catalyst is supported on silica.

(5) The content of silica is 20 to 60% by weight based on the total weight of the silica-supported catalyst comprising the catalyst component and silica.
The method for preparing a catalyst according to (4), wherein (6) The raw material of the silica carrier is a sol stabilized with ammonium ions (4) or (5).
The method for preparing a catalyst according to any one of the above. (7) calcining a dried product obtained by spray-drying or evaporating to dryness a raw material mixture containing the catalyst component at a temperature of 500 to 700 ° C in a gas atmosphere substantially free of oxygen. A method for preparing a catalyst according to any one of (1) to (6).

(8) Prior to the firing,
Pre-firing at 200-400 ° C (7)
3. The method for preparing a catalyst according to 1. (9) In producing an unsaturated nitrile by subjecting an alkane to a gas phase catalytic ammoxidation reaction, an aqueous solution or an aqueous suspension containing oxalic acid and a niobium compound is cooled, and then a niobium-containing liquid obtained by filtration is subjected to oxalic acid / When the molar ratio of niobium is 2
4. A method for producing an unsaturated nitrile, comprising using a niobium-containing catalyst adjusted to be 4 and prepared as a niobium raw material liquid. (10) The niobium compound is at least one or more selected from niobate and niobium hydrogen oxalate (9).
5. The method for producing an unsaturated nitrile according to the above. (11) The method for producing an unsaturated nitrile according to any of (9) or (10), wherein the catalyst is represented by the following general composition formula.

[0010] _{Mo 1 V a Nb b X c} Z d O n (1) ( wherein, at least one element component X is selected from Te and Sb, component Z is W, Cr, Ta, Ti, Z
r, Hf, Mn, Re, Fe, Ru, Co, Rh, N
i, Pd, Pt, Ag, Zn, B, Al, Ga, In,
Ge, Sn, Pb, P, Bi, Y, at least one element selected from rare earth elements and alkaline earth metals, a, b, c, d, and n each represent an atomic ratio per Mo atom; 1 ≦ a ≦ 1, 0.01 ≦ b ≦ 1, 0.0
1 ≦ c ≦ 1, 0 ≦ d ≦ 0.1, and n is a number determined by the oxidation state of the constituent metal. (12) The method for producing an unsaturated nitrile according to any one of (9) to (11), wherein the catalyst is supported on silica. (13) The method for producing unsaturated nitrile according to (12), wherein the content of silica is 20 to 60% by weight based on the total weight of the silica-supported catalyst comprising the catalyst component and silica.

(14) The raw material of the silica carrier is a sol stabilized with ammonium ions.
The method for producing an unsaturated nitrile according to any one of 2) and (13). (15) A dried product obtained by spray-drying or evaporating to dryness a raw material mixture containing the catalyst component is calcined at a temperature of 500 to 700 ° C. in a gas atmosphere containing substantially no oxygen. (9)-
(14) The method for producing an unsaturated nitrile according to any of (14). (16) Prior to the sintering, under air atmosphere, 200 to 4
(15) The method for producing an unsaturated nitrile according to (15), wherein a catalyst obtained by pre-baking at 00 ° C. is used. (17) The method according to any one of (9) to (16), wherein the alkane is propane or isobutane. Hereinafter, the present invention will be described in detail.

As the niobium compound used in the method of the present invention, niobate and niobium hydrogen oxalate can be suitably used. Note that niobic acid includes niobium hydroxide and niobium oxide. These niobium compounds can be used in solid or suspension form. Niobic acid can be washed with aqueous ammonia and / or water before use. These niobium compounds may be deteriorated by long-term storage or dehydration. In the present invention, it is preferable to use fresh compounds immediately after preparation, but compounds that are slightly altered can also be used.

As the oxalic acid used in the method of the present invention, oxalic anhydride or oxalic acid dihydrate can be suitably used. When niobium hydrogen oxalate is used as the niobium compound, oxalic acid may not be added. An aqueous solution or suspension can be obtained by adding these niobium compounds and oxalic acid to water and stirring. When suspending, the dissolution of the niobium compound can be promoted by adding a small amount of aqueous ammonia or by heating. The niobium concentration of this aqueous solution or aqueous suspension is preferably about 0.2 to 0.8 (mol-Nb / Kg-solution).

The prepared oxalic acid / niobium molar ratio is 3 to 3.
About 6 is preferable. When the molar ratio of oxalic acid / niobium is large, the solubility of the niobium compound increases, and after cooling, the precipitation of the niobium component is small and the recovery rate of niobium is increased. Lower. Conversely, when the oxalic acid / niobium molar ratio is small, the amount of insoluble niobium compounds increases, and the recovery rate of niobium may decrease. Then, the aqueous solution or aqueous suspension is cooled and filtered to obtain a niobium-containing liquid.
Cooling can be conveniently performed by ice cooling, and filtration can be conveniently performed by decantation or filtration.

The niobium-containing liquid must be adjusted to a molar ratio of oxalic acid / niobium of 2 to 4, preferably 2 to 3.5. This adjustment can be performed by adding a niobium compound selected from niobate and niobium hydrogen oxalate, or oxalic acid to the niobium-containing liquid. In general, the oxalic acid / niobium molar ratio, the niobium concentration and the cooling temperature are appropriately controlled so that the oxalic acid / niobium can be directly controlled.
A niobium-containing liquid having a niobium molar ratio of 2 to 4 can be obtained.

The preferred catalyst used in the present invention is represented by the following general composition formula (1). _{Mo 1 V a Nb b X c} Z d O n (1) ( wherein, at least one element component X is selected from Te and Sb, component Z is W, Cr, Ta, Ti, Z
r, Hf, Mn, Re, Fe, Ru, Co, Rh, N
i, Pd, Pt, Ag, Zn, B, Al, Ga, In,
Ge, Sn, Pb, P, Bi, Y, at least one element selected from rare earth elements and alkaline earth metals, a, b, c, d, and n each represent an atomic ratio per Mo atom; 1 ≦ a ≦ 1, 0.01 ≦ b ≦ 1, 0.0
1 ≦ c ≦ 1, 0 ≦ d ≦ 0.1, and n is a number determined by the oxidation state of the constituent metal. The component X in the formula (1) is preferably Te. Component Z is preferably at least one or more elements selected from rare earth elements and Y, and particularly preferably Yb. The atomic ratios a, b, c, and d per Mo atom are 0.2 to 0.2, respectively.
0.5, 0.01-0.5, 0.1-0.5, 0.00
5-0.05 is preferred. The catalyst used in the present invention may or may not be supported on a carrier, but is preferably a supported catalyst.

The carrier preferably used is silica,
The content of the support silica is 20 to 60% by weight, preferably 2 to 60% by weight of the total weight of the silica-supported catalyst comprising the catalyst component and silica.
0 to 40% by weight. The raw material of the component metal for preparing the catalyst of the present invention is not particularly limited, but the following compounds can be suitably used.

As the raw materials for Mo and V, ammonium heptamolybdate and ammonium metavanadate can be suitably used, respectively. As the raw materials for Te and Sb, telluric acid and antimony oxide can be suitably used, respectively. As a raw material of the component Z, an organic acid salt, nitrate, chloride, hydroxide, oxide or the like of each metal can be used. As a raw material of silica, a silica sol can be suitably used. It is preferable to use a sol stabilized with ammonium ions rather than a silica sol stabilized with alkali metal ions.

The preparation of the catalyst of the present invention can be carried out, for example, through the following three steps of raw material preparation, drying and calcination. (Raw material preparation step) A mixed aqueous solution of ammonium heptamolybdate, ammonium metavanadate and telluric acid is prepared. When antimony is used, a slurry composed of an aqueous solution of ammonium metavanadate and antimony oxide is heated under reflux conditions, ammonium heptamolybdate is added, and if necessary, telluric acid is added to prepare a mixed aqueous solution. To this mixed aqueous solution, a niobium raw material liquid obtained in the present invention and an aqueous solution containing the component Z of the formula (1), for example, an ytterbium acetate aqueous solution can be sequentially added under stirring to obtain a raw material mixture. When preparing a silica-supported catalyst, a raw material mixture can be obtained by adding silica sol to this mixture under stirring.

(Drying Step) The preparation liquid obtained in the raw material preparation step is dried by a spray drying method or an evaporation to dryness method to obtain a dry powder. Atomization in the spray drying method can be performed by a centrifugal method, a two-fluid nozzle method, or a high-pressure nozzle method. As the drying heat source, air heated by steam, an electric heater, or the like can be used. The dryer inlet temperature of the hot air is preferably from 150 to 300C. (Firing step) An oxide catalyst can be obtained by firing the dry powder obtained in the drying step. The firing is performed under a gas atmosphere substantially free of oxygen such as nitrogen,
It can be carried out at 700C, preferably 550-650C. The firing time is 0.5 to 20 hours, preferably 1 hour.
~ 8 hours. The firing can be performed using a rotary furnace, a tunnel furnace, a tubular furnace, a fluidized-bed firing furnace, or the like, and can be performed while flowing a gas substantially containing no oxygen. Before this calcination, under air atmosphere or air circulation,
Pre-baking can be performed at 400 ° C. for 1 to 5 hours.

In the presence of the catalyst thus prepared,
Alkanes can be reacted in gaseous phase with ammonia and oxygen to produce the corresponding unsaturated nitriles.
Alkane and ammonia feeds need not be of high purity, and industrial grade gases can be used. Preferably, the alkane is propane or isobutane.

As the supply oxygen source, air, pure oxygen or air enriched with pure oxygen can be used. further,
Helium, neon, argon, carbon dioxide, water vapor, nitrogen, or the like may be supplied as a diluting gas. The molar ratio of ammonia supplied to the reaction to the alkane is 0.3-1.
5, preferably 0.8 to 1.2. The reaction pressure is 0.
It is 1 to 10 atm, preferably 1 to 3 atm. The reaction temperature is 350 ° C to 500 ° C, preferably 380 ° C to 47 ° C.
0 ° C.

The contact time is 0.1 to 30 (sec · g / c)
c), preferably 0.5 to 10 (sec · g / cc). The reaction system can adopt a fixed bed, fluidized bed, moving bed, etc., but it is easy to remove the heat of reaction and can keep the temperature of the catalyst layer almost uniform, and it is necessary to extract or add the catalyst from the reactor during operation. For example, a fluidized bed reaction is preferred.

BEST MODE FOR CARRYING OUT THE INVENTION The present invention will be described below with reference to an example of preparing a niobium raw material liquid, an example of preparing a catalyst, and an example of producing acrylonitrile by a gas phase catalytic ammoxidation reaction of propane. Is not limited to these examples as long as the gist is not exceeded.

The results of this ammoxidation reaction were evaluated by the propane conversion, acrylonitrile selectivity and acrylonitrile yield defined by the following formula. Propane conversion (%) = (number of moles of propane reacted)
/ (Mol number of propane supplied) × 100 Acrylonitrile selectivity (%) = (mol number of acrylonitrile formed) / (mol number of reacted propane) × 1
00 Acrylonitrile yield (%) = (mol number of acrylonitrile generated) / (mol number of supplied propane) × 10
0

[0025]

(Example 1) (Preparation of niobium raw material liquid) 664.0 g of niobic acid containing 80.0% by weight of Nb ₂ O _{5 in} 6562 g of water and oxalic acid dihydrate [H ₂ C ₂ O ₄ · 2H ₂ O] 2774.
0 g were mixed. The charged oxalic acid / niobium molar ratio was 5.5, and the charged niobium concentration was 0.4 (mol-Nb /
Kg-liquid). This mixture was heated and stirred at 95 ° C. for 1 hour to obtain an aqueous solution in which niobium was dissolved.
This aqueous solution was allowed to stand, cooled with ice, and then the solid was separated by suction filtration to obtain a uniform niobium-containing liquid. The oxalic acid / niobium molar ratio of this niobium-containing liquid was 2.6 according to the following analysis.

A 10 g portion of this niobium-containing liquid was precisely weighed in a crucible, dried at 95 ° C. overnight, and heat-treated at 600 ° C. for 1 hour.
0.625 g of Nb ₂ O ₅ was obtained. From these results, the niobium concentration was 0.47 (mol-Nb / Kg-solution).
In a 300 ml glass beaker, 3 g of the niobium-containing liquid was precisely weighed, and 200 ml of hot water at about 80 ° C. was added.
10 ml of 1 sulfuric acid was added. The obtained solution was titrated with 1 / 4N KMnO ₄ with stirring while maintaining the liquid temperature at 70 ° C on a hot stirrer. The point at which the faint pale pink color by KMnO ₄ continued for about 30 seconds or more was determined as the end point. The concentration of oxalic acid was calculated from the titer according to the following equation.
22 (mol-oxalic acid / Kg-solution). 2KMnO ₄ + 3H ₂ SO ₄ + 5H ₂ C ₂ O ₄ → K ₂ S
O ₄ +2 MnSO ₄ + 10CO ₂ + 8H ₂ O The obtained niobium-containing liquid was used as a niobium raw material liquid for the following catalyst preparation without adjusting the molar ratio of oxalic acid / niobium. (Preparation of catalyst) The composition formula of the catalyst component is Mo ₁ V _0.32 Nb
A _0.12 Te _0.22 O _n, SiO ₂ content of 30 wt%
Was prepared as follows.

[0027] Ammonium heptamolybdate in water 2300g _{[(NH 4) 6 Mo 7 O} 24 · 4H 2 O ] 546.
7 g, ammonium metavanadate [NH ₄ VO ₃ ] 1
16.3 g and telluric acid [H ₆ TeO ₆ ] 156.9
g were sequentially added and dissolved by heating to 60 ° C., followed by cooling to 30 ° C. to obtain a mixed aqueous solution. Next, 785.0 g of the above niobium raw material liquid and 1000 g of silica sol containing 30% by weight as silica were sequentially added to and mixed with this mixed aqueous solution to obtain a catalyst raw material mixture. This raw material mixture was dried with a centrifugal spray drier at an inlet temperature of 240 ° C. and an outlet temperature of 145 ° C. to obtain a fine spherical dry powder. The obtained dry powder was calcined at 275 ° C. for 2 hours in an air atmosphere. 85 g of this powder was filled in a SUS tube having a diameter of 1 inch, and the temperature was raised to 600 ° C. under a nitrogen gas flow of 150 Ncc / min.
For 2 hours to obtain a silica-supported catalyst. (Ammoxidation reaction of propane) A catalyst prepared by preparing a Vycor glass fluidized bed type reaction tube having an inner diameter of 25 mm was mixed with 45 mL of a catalyst.
g, propane: ammonia: oxygen: helium = 1: 1.2: 3: 1 at a reaction temperature of 430 ° C. and a normal reaction pressure.
A contact time of 3.0 (sec · g /
cc). Table 1 shows the obtained results.

The contact time is defined by the following equation. Contact time (sec · g / cc) = (W / F) × 273 /
(Where W is the amount of the charged catalyst (g), F is the raw material mixed gas flow rate (Ncc / sec), and T is the reaction temperature (° C.))

(Example 2) (Preparation of niobium raw material liquid) The niobium-containing liquid having a oxalic acid / niobium molar ratio of 2.6 in Example 1 was further adjusted to have a oxalic acid / niobium molar ratio of 3.0. Oxalic acid dihydrate [H ₂
C ₂ O ₄ .2H ₂ O], and dissolve by heating.
Cooled to 30 ° C. The obtained liquid was used as a niobium raw material liquid for preparing the following catalyst. The niobium concentration in this niobium raw material solution was analyzed in the same manner as in Example 1, and as a result,
(Mol-Nb / Kg-solution). (Preparation of catalyst) The composition formula of the catalyst component is Mo ₁ V _0.32 Nb
A _0.12 Te _0.22 O _n, SiO ₂ content of 30 wt%
Was prepared in the same manner as in Example 1 except that the above niobium raw material liquid was used and the amount used was changed to 802.1g to obtain a silica-supported catalyst. (Ammoxidation reaction of propane) Using the obtained catalyst,
An ammoxidation reaction of propane was performed under the same conditions as in Example 1. Table 1 shows the results.

(Comparative Example 1) (Preparation of Niobium Raw Material Liquid) The oxalic acid / niobium molar ratio of niobium in which niobium was dissolved, obtained in the same manner as in Example 1, was 5.5.
This liquid was used as a niobium raw material liquid for the following catalyst preparation without ice cooling. The niobium concentration in this niobium raw material liquid was analyzed in the same manner as in Example 1, and as a result, the niobium concentration was 0.41%.
(Mol-Nb / Kg-solution). (Preparation of catalyst) The composition formula of the catalyst component is Mo ₁ V _0.32 Nb
A _0.12 Te _0.22 O _n, SiO ₂ content of 30 wt%
The silica-supported catalyst was prepared in the same manner as in Example 1 except that the above niobium raw material liquid was used and the amount of use was 899.9 g. (Ammoxidation reaction of propane) Using the obtained catalyst,
An ammoxidation reaction of propane was performed under the same conditions as in Example 1. Table 1 shows the results.

(Example 3) (Preparation of niobium raw material liquid) 66.4 g of niobic acid containing 782 g of water and 80.0% by weight as Nb ₂ O ₅ and oxalic acid dihydrate [H ₂ C ₂ O ₄ 2H ₂ O] (151.3 g) was mixed. The molar ratio of oxalic acid / niobium charged was 3.
0, the charged niobium concentration is 0.4 (mol-Nb / Kg
-Liquid). This mixture was heated and stirred at 95 ° C. for 1 hour to obtain an aqueous suspension containing an insoluble niobium component. The aqueous suspension was allowed to stand, cooled with ice, and then the solid was separated by filtration to obtain a uniform niobium-containing liquid. The niobium concentration and the oxalic acid / niobium molar ratio in this niobium-containing liquid were analyzed in the same manner as in Example 1, and as a result, 0.41 (mol-
Nb / Kg-solution) and 2.8. This niobium-containing liquid was used as a niobium raw material liquid for the following catalyst preparation without adjusting the molar ratio of oxalic acid / niobium. (Preparation of catalyst) The composition formula of the catalyst component is Mo ₁ V _0.32 Nb
A _0.12 Te _0.22 O _n, SiO ₂ content of 30 wt%
The silica-supported catalyst was prepared in the same manner as in Example 1 except that the above niobium raw material liquid was used and the amount of use was 899.9 g. (Ammoxidation reaction of propane) Using the obtained catalyst,
An ammoxidation reaction of propane was performed under the same conditions as in Example 1. Table 1 shows the results.

Example 4 (Preparation of Niobium Raw Material Liquid) 664.0 g of niobic acid containing 80.0% by weight of Nb ₂ O _{5 in} 4084 g of water and oxalic acid dihydrate [H ₂ C ₂ O ₄・ 2H ₂ O] 252.0
g were mixed. The charged oxalic acid / niobium molar ratio was 0.5, and the charged niobium concentration was 0.8 (mol-Nb /
Kg-liquid). This mixture was heated and stirred at 95 ° C. for 1 hour to obtain an aqueous suspension containing an insoluble niobium component. The aqueous suspension was allowed to stand, cooled with ice, and then the solid was separated by filtration to obtain a uniform niobium-containing liquid. The niobium concentration and the oxalic acid / niobium molar ratio in the niobium-containing liquid were analyzed in the same manner as in Example 1, and as a result, 0.16 (m
ol-Nb / Kg-solution) and 2.2. This niobium-containing liquid was further added with a oxalic acid / niobium molar ratio of 3.0.
Then, oxalic acid dihydrate was added to the mixture, and the mixture was dissolved by heating, and then cooled to 30 ° C. The obtained liquid was used as a niobium raw material liquid for preparing the following catalyst. As a result of analyzing the niobium concentration in this solution in the same manner as in Example 1, the niobium concentration was 0.158.
(Mol-Nb / Kg-solution). (Preparation of catalyst) The composition formula of the catalyst component is Mo ₁ V _0.32 Nb
A _0.12 Te _0.22 O _n, SiO ₂ content of 30 wt%
Was prepared in the same manner as in Example 1 except that the above niobium raw material liquid was used and the amount used was 2335.2 g, to obtain a silica-supported catalyst. (Ammoxidation reaction of propane) Using the obtained catalyst,
An ammoxidation reaction of propane was performed under the same conditions as in Example 1. Table 1 shows the results.

Example 5 (Preparation of Niobium Raw Material Liquid) A niobium raw material liquid having a oxalic acid / niobium molar ratio of 3.0 was obtained in the same manner as in Example 2. (Preparation of catalyst) The composition formula of the catalyst component is Mo ₁ V _0.32 Nb
A _0.12 Te _0.22 O _n, SiO ₂ content of 50 wt%
Was prepared as follows. 1600 g of water
Ammonium heptamolybdate [(NH ₄ ) ₆ Mo
₇ O ₂₄ · 4H ₂ O] 390.5G, ammonium metavanadate [NH ₄ VO _3] 83.1g and telluric acid [H ₆ TeO _6] 112.0g successively added, was dissolved by heating to 60 ° C., The mixture was cooled to 30 ° C. to obtain a mixed aqueous solution. Next, the niobium raw material liquid 57 was added to the mixed aqueous solution.
2.9 g and 1667 g of a silica sol containing 30% by weight as silica were sequentially added and mixed to obtain a catalyst raw material mixture. This raw material mixture was dried with a centrifugal spray drier at an inlet temperature of 240 ° C. and an outlet temperature of 145 ° C. to obtain a fine spherical dry powder. The obtained dry powder was calcined at 275 ° C. for 2 hours in an air atmosphere. 85 g of the powder was filled in a SUS tube having a diameter of 1 inch, and calcined at 600 ° C. for 2 hours under a nitrogen gas flow of 150 Ncc / min to obtain a silica-supported catalyst.

(Ammoxidation reaction of propane) Using the obtained catalyst, an ammoxidation reaction of propane was carried out under the same conditions as in Example 1. Table 1 shows the results.

Comparative Example 2 (Preparation of Niobium Raw Material Liquid) A niobium raw material liquid having a oxalic acid / niobium molar ratio of 5.5 was obtained in the same manner as in Comparative Example 1. (Preparation of catalyst) The composition formula of the catalyst component is Mo ₁ V _0.32 Nb
A _0.12 Te _0.22 O _n, SiO ₂ content of 50 wt%
Was prepared in the same manner as in Example 5 except that the above niobium raw material liquid was used and the amount used was 642.8 g, to obtain a silica-supported catalyst. (Ammoxidation reaction of propane) Using the obtained catalyst,
An ammoxidation reaction of propane was performed under the same conditions as in Example 1. Table 1 shows the results. (Example 6) (Preparation of niobium raw material liquid) A niobium raw material liquid having a molar ratio of oxalic acid / niobium of 2.6 was obtained in the same manner as in Example 1. (Preparation of catalyst) The composition formula is Mo ₁ V _0.32 Nb _0.12 Te _0.22
The catalyst represented by O _n, was prepared in the following manner.

[0036] Ammonium heptamolybdate in water 1650g _{[(NH 4) 6 Mo 7 O} 24 · 4H 2 O ] 390.
5 g, ammonium metavanadate [NH ₄ VO ₃ ] 8
3.1 g and telluric acid [H ₆ TeO ₆ ] 112.0 g
Were sequentially added and dissolved by heating to 60 ° C., and then cooled to 30 ° C. to obtain a mixed aqueous solution. Then, in this mixed aqueous solution,
560.7 g of the above niobium raw material liquid was added and mixed to obtain a catalyst raw material preparation liquid. This raw material mixture was dried with a centrifugal spray drier at an inlet temperature of 240 ° C. and an outlet temperature of 145 ° C. to obtain a fine spherical dry powder. The obtained dry powder was calcined at 275 ° C. for 2 hours in an air atmosphere. 85 g of this powder
Is filled into a 1 inch diameter SUS tube, and 150 Ncc /
The catalyst was obtained by calcining at 600 ° C. for 2 hours under a nitrogen gas flow of min. (Ammoxidation reaction of propane) 1 g of catalyst is 10 mm
At a reaction temperature of 430 ° C. under a normal reaction pressure of propane: ammonia: oxygen: helium =
A mixed gas having a molar ratio of 1: 1.2: 3: 12 was passed at a contact time of 1.0 (sec · g / cc). Table 1 shows the obtained results.

(Comparative Example 3) (Preparation of niobium raw material liquid) 66.4 g of niobic acid containing 80.0% by weight of Nb ₂ O _{5 in} 803 g of water and oxalic acid dihydrate [H ₂ C ₂ O ₄ [2H ₂ O] 131.1 g was mixed. The molar ratio of oxalic acid / niobium charged was 2.
6. The niobium concentration of the charge is 0.4 (mol-Nb / Kg
-Liquid). This mixture was heated and stirred at 95 ° C. for 1 hour, but was in a suspended state. This suspension liquid was used as a niobium raw material for preparing the following catalyst. The niobium concentration in this niobium raw material solution was analyzed in the same manner as in Example 1, and as a result, it was 0.41 (mol-Nb / Kg-solution). (Preparation of catalyst) The composition formula is Mo ₁ V _0.32 Nb _0.12 Te _0.22
The catalyst represented by O _n, using the above-mentioned niobium raw material liquid, and other usage was with 642.8g was obtained a catalyst was prepared in the same manner as in Example 6. (Ammoxidation reaction of propane) Using the obtained catalyst,
An ammoxidation reaction of propane was performed under the same conditions as in Example 6. Table 1 shows the results.

(Example 7) (Preparation of niobium raw material liquid) In the same manner as in Example 2, a niobium raw material liquid having a oxalic acid / niobium molar ratio of 3.0 was obtained. (Preparation of catalyst) The composition formula of the catalyst component is Mo ₁ V _0.32 Nb
A _0.12 Te _0.22 Yb _0.010 O _n, to prepare a SiO ₂ content of 30 wt% silica supported catalyst as follows. Ammonium heptamolybdate [(NH
_{4) 6 Mo 7 O 24 ·} 4H 2 O ] 542.0G, ammonium metavanadate [NH ₄ VO _3] 115.3g and telluric acid [H ₆ TeO _6] 155.5g added sequentially,
After heating to 60 ° C. to dissolve, the mixture was cooled to 30 ° C. to obtain a mixed aqueous solution. Next, 795.2 g of the above-mentioned niobium raw material liquid, and an aqueous solution obtained by dissolving 12.88 g of ytterbium acetate [Yb (CH ₃ COO) ₃ .4H ₂ O] in 250 g of water, and 30% by weight of silica were contained in the mixed aqueous solution. Then, 1000 g of silica sol was sequentially added and mixed to obtain a catalyst raw material mixture. This raw material mixture was dried with a centrifugal spray drier at an inlet temperature of 240 ° C. and an outlet temperature of 145 ° C. to obtain a fine spherical dry powder. The obtained dry powder was calcined at 275 ° C. for 2 hours in an air atmosphere. 85 g of this powder
Is filled into a 1 inch diameter SUS tube, and 150 Ncc /
The catalyst was obtained by calcining at 600 ° C. for 2 hours under a nitrogen gas flow of min. (Ammoxidation reaction of propane) Using the obtained catalyst,
An ammoxidation reaction of propane was performed under the same conditions as in Example 1. Table 1 shows the results.

(Example 8) (Preparation of niobium raw material liquid) Niobium hydrogen oxalate 917 containing 14.9% by weight as Nb ₂ O _{5 in} 1000 g of water
g were mixed. The charged niobium concentration is 0.54 (mol
-Nb / Kg-liquid). This mixture was heated and stirred at 95 ° C. for 1 hour to obtain a uniform aqueous solution. As a result of analyzing the oxalic acid / niobium molar ratio in the same manner as in Example 1, it was 5.2. After leaving this aqueous solution to stand still and cooling on ice,
The solid was filtered off to obtain a uniform niobium-containing liquid. The niobium concentration and the oxalic acid / niobium molar ratio in this niobium-containing liquid were analyzed in the same manner as in Example 1, respectively.
0.66 (mol-Nb / Kg-solution) and 2.4. The niobium-containing solution was further added with a oxalic acid / niobium molar ratio of 3.0 and a niobium concentration of 0.46 (mol-Nb / K).
g-liquid) of oxalic acid dihydrate [H ₂ C ₂ O ₄
[2H ₂ O] and water were added and dissolved by heating and stirring, and then cooled to 30 ° C. The obtained liquid was used as a niobium raw material liquid for preparing the following catalyst. (Preparation of catalyst) The composition formula of the catalyst component is Mo ₁ V _0.32 Nb
A _0.12 Te _0.22 O _n, SiO ₂ content of 30 wt%
Was prepared in the same manner as in Example 2 except that the above-mentioned niobium raw material liquid was used to obtain a silica-supported catalyst. (Ammoxidation reaction of propane) Using the obtained catalyst,
An ammoxidation reaction of propane was performed under the same conditions as in Example 1. Table 1 shows the results.

[0040]

[Table 1]

[0041]

According to the present invention, it is possible to prepare a catalyst having a high nitrile yield and exhibiting sufficient catalytic performance even when supported on a carrier component, by using a raw material liquid of niobium which is easily prepared.

──────────────────────────────────────────────────続 き Continued on the front page (51) Int.Cl. ⁶ Identification code FI C07C 253/24 C07C 253/24 255/08 255/08

Claims (17)

[Claims] 1. A method for preparing a catalyst containing niobium for use in an ammoxidation reaction of an alkane, comprising cooling an aqueous solution or an aqueous suspension containing oxalic acid and a niobium compound, and filtering the aqueous solution or the niobium-containing liquid obtained by filtering. A method for preparing a niobium-containing catalyst, comprising adjusting the molar ratio of acid / niobium to 2 to 4 and using the resultant as a niobium raw material liquid. 2. The method according to claim 1, wherein the niobium compound is at least one member selected from niobic acid and niobium hydrogen oxalate. 3. The catalyst according to claim 1, wherein the catalyst is a compound represented by the following general composition formula (1).
The method for preparing a catalyst according to the above. _{Mo 1 V a Nb b X c} Z d O n (1) ( wherein, at least one element component X is selected from Te and Sb, component Z is W, Cr, Ta, Ti, Z
r, Hf, Mn, Re, Fe, Ru, Co, Rh, N
i, Pd, Pt, Ag, Zn, B, Al, Ga, In,
Ge, Sn, Pb, P, Bi, Y, at least one element selected from rare earth elements and alkaline earth metals, a, b, c, d, and n each represent an atomic ratio per Mo atom; 1 ≦ a ≦ 1, 0.01 ≦ b ≦ 1, 0.0
1 ≦ c ≦ 1, 0 ≦ d ≦ 0.1, and n is a number determined by the oxidation state of the constituent metal. ) 4. The method according to claim 1, wherein the catalyst is supported on silica. 5. The method for preparing a catalyst according to claim 4, wherein the content of silica is from 20 to 60% by weight based on the total weight of the silica-supported catalyst comprising the catalyst component and silica. 6. The method according to claim 4, wherein the raw material of the silica carrier is a sol stabilized with ammonium ions. 7. A dried product obtained by spray-drying or evaporating to dryness a raw material mixture containing the catalyst component is calcined at a temperature of 500 to 700 ° C. in a gas atmosphere substantially free of oxygen. 7. A method according to claim 1, wherein:
The method for preparing a catalyst according to the above item. 8. Prior to the sintering, 20 minutes under air atmosphere
The method for preparing a catalyst according to claim 7, wherein pre-calcination is performed at 0 to 400C. 9. In producing an unsaturated nitrile by subjecting an alkane to a gas phase catalytic ammoxidation reaction, an aqueous solution or an aqueous suspension containing oxalic acid and a niobium compound is cooled, and then a niobium-containing liquid obtained by filtration is subjected to a sulfuric acid filtration. A method for producing an unsaturated nitrile, comprising adjusting a molar ratio of acid / niobium to 2 to 4 and using a niobium-containing catalyst prepared as a niobium raw material liquid. 10. The method for producing an unsaturated nitrile according to claim 9, wherein the niobium compound is at least one selected from niobic acid and niobium hydrogen oxalate. 11. The method for producing an unsaturated nitrile according to claim 9, wherein the catalyst is a compound represented by the following general composition formula (1). _{Mo 1 V a Nb b X c} Z d O n (1) ( wherein, at least one element component X is selected from Te and Sb, component Z is W, Cr, Ta, Ti, Z
r, Hf, Mn, Re, Fe, Ru, Co, Rh, N
i, Pd, Pt, Ag, Zn, B, Al, Ga, In,
Ge, Sn, Pb, P, Bi, Y, at least one element selected from rare earth elements and alkaline earth metals, a, b, c, d, and n each represent an atomic ratio per Mo atom; 1 ≦ a ≦ 1, 0.01 ≦ b ≦ 1, 0.0
1 ≦ c ≦ 1, 0 ≦ d ≦ 0.1, and n is a number determined by the oxidation state of the constituent metal. ) 12. The method for producing an unsaturated nitrile according to claim 9, wherein the catalyst is supported on silica. 13. The method for producing an unsaturated nitrile according to claim 12, wherein the content of silica is 20 to 60% by weight based on the total weight of the silica-supported catalyst comprising the catalyst component and silica. 14. The method according to claim 1, wherein the raw material of the silica carrier is a sol stabilized with ammonium ions.
A method for producing an unsaturated nitrile according to claim 2 or 13. 15. A dried material obtained by spray-drying or evaporating to dryness a raw material preparation liquid containing the catalyst component, and calcining at a temperature of 500 to 700 ° C. in a gas atmosphere substantially free of oxygen. The method for producing an unsaturated nitrile according to any one of claims 9 to 14, wherein a catalyst obtained by the method is used. 16. Prior to the firing, 2
The method for producing an unsaturated nitrile according to claim 15, wherein a catalyst obtained by pre-baking at 00 to 400 ° C is used. 17. The method for producing an unsaturated nitrile according to claim 9, wherein the alkane is propane or isobutane.