JP6584882B2 - Method for producing oxide catalyst, method for producing unsaturated acid, and method for producing unsaturated nitrile - Google Patents

Description

  The present invention relates to a method for producing an oxide catalyst, and a method for producing an unsaturated acid and a method for producing an unsaturated nitrile using the oxide catalyst obtained by the production method.

Conventionally, a method for producing a corresponding unsaturated carboxylic acid or unsaturated nitrile from propylene or isobutylene by gas phase catalytic oxidation or gas phase catalytic ammoxidation is well known. In recent years, attention has been focused on a method of producing a corresponding unsaturated acid or unsaturated nitrile by gas phase catalytic oxidation or gas phase catalytic ammoxidation of propane or isobutane instead of propylene or isobutylene.
Among these, a composite metal oxide catalyst containing niobium (Nb) has been proposed as a catalyst for vapor phase ammoxidation. In order to produce a composite metal oxide catalyst, for example, a slurry containing a metal salt constituting the catalyst is prepared, spray-dried, and calcined. At this time, if the slurry containing the metal salt is not in a uniform state, the resulting catalyst will also be inhomogeneous, making it difficult to obtain a composite metal oxide having an optimized composition. Therefore, it is desired to prepare a slurry in which the metal salt is uniformly dissolved. However, depending on the metal species to be blended, there are some which form a hardly soluble salt, and it is necessary to sufficiently dissolve the hardly soluble salt.
In order to dissolve a hardly water-soluble metal species, a method of adding various acids, bases, chelate compounds and the like and heating them is known. Among them, elements such as niobium and tantalum are known to be poorly water-soluble, and it is not easy to prepare a uniform solution. Therefore, an attempt has been made to prepare a solution in which the above elements are uniformly dissolved. For example, Patent Document 1 describes a method of preparing a Nb aqueous solution by adding a dicarboxylic acid such as oxalic acid to dissolve a Nb compound in order to prepare a composite metal oxide. Patent Document 2 describes a method for producing a catalyst in which Nb is present in the form of a complex with a complexing agent composed of a compound having a hydroxyl group bonded to an oxygen atom or a carbon atom. Patent Document 3 includes a mixing tank having corrosion resistance and provided with stirring means, heating means, and cooling means, and a filter for filtering the undissolved Nb compound and the precipitated dicarboxylic acid, A manufacturing apparatus is described that performs filtration while applying pressure at the stage of filtration.

Japanese Patent No. 3938225 Japanese Patent No. 4666334 International Publication No. 2012/105543

Patent Document 1 describes an optimal ratio of dicarboxylic acid and Nb compound when preparing a catalyst for producing acrylonitrile from propane. Patent Document 2 describes an optimum complex formation rate when the catalyst is prepared. When a dicarboxylic acid is added at a ratio described in these documents to prepare a niobium solution, the Nb compound is dissolved on a laboratory scale. However, when it is scaled up to an industrial level, there remains an undissolved Nb compound, dicarboxylic acid is deposited in the middle of the pipe, or a niobium solution in which the dicarboxylic acid is dissolved more than expected is obtained. There's a problem.
If there is a large amount of undissolved Nb, the undissolved Nb remains in the Nb aqueous mixture without being sufficiently filtered off. As a result, the Nb component is dispersed non-uniformly in the obtained catalyst, and the yield of the target product is lowered even when the catalyst is used. In addition, since the concentration of Nb dissolved in the Nb aqueous mixture is lowered, the solid content concentration during catalyst preparation is reduced as a result, the catalyst shape and strength are deteriorated, and the yield of the target product in the fluidized bed reaction is reduced. The problem of deteriorating arises.
Further, Patent Document 3 describes a mixed liquid production apparatus and a mixed liquid preparation method that can reduce the undissolved residue and precipitation of the Nb compound even on an industrial scale and achieve high niobium recovery and productivity. However, the apparatus and method described in Patent Document 3 require a long time until niobic acid is dissolved, a long time is required for filtration, and the concentration of the resulting niobium solution is low. There is.
Therefore, the present invention has been made in view of the above circumstances, and is a method for producing an oxide catalyst containing niobium and used in a gas phase catalytic oxidation reaction or a gas phase catalytic ammoxidation reaction. A method for producing an oxide catalyst capable of increasing the solubility of the Nb raw material compound when preparing a liquid containing an acid and reducing the dissolution time and the filtration time, and a method for producing an unsaturated acid using the oxide catalyst, and It aims at providing the manufacturing method of unsaturated nitrile.

As a result of intensive investigations to achieve the above-mentioned problems, the present inventors have found that the Nb raw material compound residue rate (hereinafter simply referred to as “Nb residue rate”), which is one of the raw materials for preparing the oxide catalyst. Is less than a specific value, the niobium solubility is improved, and the dissolution time and filtration time can be shortened, and the present invention has been completed.
That is, the present invention is as follows.
[1] A method for producing an oxide catalyst used in the production of an unsaturated acid or an unsaturated nitrile, comprising a step of obtaining an Nb aqueous mixture by mixing an Nb raw material compound, an organic acid and water, The manufacturing method of an oxide catalyst whose Nb residue rate of a raw material compound is less than 5.0%.
[2] The production method of [1], wherein the Nb raw material compound is niobic acid.
[3] The production method of [1] or [2], wherein the Nb raw material compound has an average particle size of 1.0 to 100 μm.
[4] The method according to any one of [1] to [3], wherein the organic acid is one or more selected from the group consisting of dicarboxylic acids and anhydrides or hydrates thereof.
[5] Filtering the Nb aqueous mixture to obtain an Nb organic acid aqueous solution, and mixing the Nb organic acid aqueous solution with a complexing agent or an aqueous solution of a complexing agent to obtain an Nb organic acid compound / complexing agent aqueous solution. A process comprising any one of [1] to [4].
[6] The process according to [5], wherein the complexing agent is at least one compound selected from the group consisting of hydrogen peroxide and monooxypolycarboxylic acids.
[7] One or two of the Nb organic acid compound / complex forming agent aqueous solution containing a compound of one or more elements selected from the group consisting of metal elements and metalloid elements other than niobium contained in the oxide catalyst The production method of [5] or [6], comprising a step of mixing with an aqueous mixture of at least seeds to obtain a catalyst raw material preparation liquid.
[8] The method according to [7], comprising: a step of drying the catalyst raw material preparation liquid to obtain a dried product; and a step of firing the dried product.
[9] The oxide catalyst includes an oxide of one or more elements selected from the group consisting of a metal element and a metalloid element and an oxide of a metalloid element, and the oxide of the one or more elements and The oxide of the one or more elements is supported on the oxide of the metalloid element in an amount of 10 to 80% by mass in terms of the oxide of the metalloid element with respect to the total mass with the oxide of the metalloid element. Any one manufacturing method of [1]-[8] which is a thing.
[10] The method according to any one of [7] to [9], wherein the oxide of the metalloid element is silica.
[11] The production method according to any one of [1] to [10], wherein the oxide catalyst includes Mo, V, Sb, and Nb.
[12] A method for producing an unsaturated acid, which comprises producing a corresponding unsaturated acid from propane or isobutane by a gas-phase catalytic oxidation reaction, wherein [1] to [11] are used as a catalyst for the gas-phase catalytic oxidation reaction. The manufacturing method of an unsaturated acid using the oxide catalyst obtained by any one manufacturing method.
[13] A method for producing an unsaturated nitrile for producing a corresponding unsaturated nitrile from propane or isobutane by gas phase catalytic ammoxidation reaction, wherein [1] to [11] are used as catalysts for the gas phase catalytic ammoxidation reaction. ] The manufacturing method of an unsaturated nitrile using the oxide catalyst obtained by any one manufacturing method of these.

  According to the present invention, there is provided a method for producing an oxide catalyst containing niobium and used for a gas phase catalytic oxidation reaction or a gas phase catalytic ammoxidation reaction, wherein Nb is prepared when a liquid containing an Nb raw material compound and an organic acid is prepared. To provide a method for producing an oxide catalyst capable of increasing the solubility of a raw material compound and shortening its dissolution time and filtration time, and a method for producing an unsaturated acid and a method for producing an unsaturated nitrile using the oxide catalyst. it can.

Hereinafter, a mode for carrying out the present invention (hereinafter simply referred to as “the present embodiment”) will be described in detail. The present invention is not limited to the following embodiment, and can be implemented with various modifications within the scope of the gist.
The method for producing an oxide catalyst according to the present embodiment is a method for producing an oxide catalyst used for producing an unsaturated acid or an unsaturated nitrile, wherein an Nb aqueous mixture is prepared by mixing an Nb raw material compound, an organic acid and water. (Nb aqueous mixture preparation step), and the Nb residue ratio of the Nb raw material compound is less than 5%. In more detail, this manufacturing method is a manufacturing method which obtains an oxide catalyst by drying and baking the catalyst raw material preparation liquid obtained through the preparation process of the said Nb aqueous mixture. Here, in the present specification, the “oxide catalyst” refers to a catalyst containing an oxide of one or more elements selected from the group consisting of metal elements and metalloid elements. As will be described later, in the case of a catalyst in which a metal or metalloid element oxide is supported on a carrier, the “oxide catalyst” is a concept including a metal or metalloid element oxide and a carrier. In the present specification, examples of the “metalloid element” include boron, silicon, aluminum, phosphorus, germanium, arsenic, antimony, tellurium, zinc, gallium, tin, bismuth, polonium, and astatine. Further, the “catalyst precursor” refers to a compound that is generated during the production process of an oxide catalyst.

(Nb aqueous mixture preparation process)
In this step, first, an Nb aqueous mixture is obtained by mixing an organic acid, a Nb raw material compound, and water by, for example, heating and stirring in a mixing tank. The Nb aqueous mixture is usually in a liquid or slurry form and may or may not be present with undissolved solids and / or precipitated solids. The mixing tank is preferably made of a corrosion-resistant material in order to prevent corrosion due to organic acids.

The Nb raw material compound is a compound that becomes a niobium source contained in the oxide catalyst, and the Nb raw material compound is not particularly limited as long as it is a compound having niobium, but since both are hardly soluble, an organic acid is allowed to coexist. To dissolve. Specific examples of the Nb raw material compound include, but are not limited to, niobium hydrogen oxalate, ammonium niobium oxalate, NbCl ₃ , NbCl ₅ , Nb ₂ (C ₂ O ₄ ) ₅ , Nb ₂ O ₅ , niobic acid, Nb (OC ₂ H ₅ ) ₅ , halides of niobium, and ammonium halides of niobium. Nb raw material compounds are used singly or in combination of two or more. Of these, niobic acid and niobium hydrogen oxalate are preferred from the viewpoint of having a small influence on other metal or metalloid elements when mixing an aqueous Nb mixture with a compound having other metal or metalloid elements. It is. Here, “niobic acid” includes niobium hydroxide and niobium oxide. Since the Nb raw material compound may be deteriorated by long-term storage or progress of dehydration, it is preferable to use the Nb raw material compound immediately after synthesis when preparing the Nb aqueous mixture. However, it may be used even if it is slightly altered immediately after synthesis.
When preparing the Nb aqueous mixture, it is preferable that the solubility of the Nb raw material compound is high and the remaining amount of the Nb raw material compound and / or organic acid in the Nb aqueous mixture is small. Thereby, the time required for filtration and the time required for dissolution of the Nb aqueous mixture described later can be shortened, and a solution can be prepared with a higher Nb concentration.

  The concentration of niobium in the Nb aqueous mixture is preferably 0.10 to 1.0 (mol-Nb / kg-solution), more preferably 0.10 to 0.90 (mol-Nb / kg-solution). More preferably, it is 0.10-0.80 (mol-Nb / kg-solution). When the niobium concentration is 0.10 (mol-Nb / kg-liquid) or more, when preparing an oxide catalyst using the Nb aqueous mixture, the amount of the Nb aqueous mixture for adding the required amount of Nb is reduced. It tends to be reduced. As a result, the solid content concentration in the catalyst raw material preparation liquid (hereinafter also simply referred to as “raw material preparation liquid”), which will be described later, can be increased, and the moldability of the catalyst can be improved. It is possible to further improve the fluidity of the product, and it tends to be easy to obtain the yield of the desired target product. On the other hand, when the niobium concentration is 1.0 (mol-Nb / kg-liquid) or less, it is possible to reduce the undissolved residue of the sparingly soluble Nb raw material compound, so that filtration becomes easy and the solid content is uniformly dispersed. Also, it tends to be easy to prepare an Nb aqueous mixture having a small concentration distribution in the liquid.

  In this embodiment, the Nb residue ratio of the Nb raw material compound calculated by the following method is less than 5.0%, preferably less than 4.0%, and more preferably less than 3.0%. Further, the lower limit of the Nb residue rate is not particularly limited, and for example, the Nb residue rate may be 0.00% or 0.01% or more. When the Nb residue ratio is less than 5.0%, the Nb raw material compound has high solubility when preparing the Nb aqueous mixture, so that the time required for dissolution is shortened, and there is no undissolved residue in the Nb aqueous mixture. Since it decreases, it becomes easy to filter and the time required for filtering tends to be shortened.

(Nb residue rate measuring method)
1) Heat 80 g of pure water to 60 ° C.
2) Add oxalic acid dihydrate (42 g) to the heated pure water and dissolve.
3) Further, 11 g of Nb raw material compound in terms of niobic acid is added and heated to 95 ° C.
4) Hold 95 ° C. for 2 hours to dissolve the Nb raw material compound.
5) Lower the temperature to 70 ° C.
6) Filter off the undissolved matter with a membrane filter (pore size: 0.1 μm).
7) Thoroughly wash the undissolved portion with warm water at 80 ° C.
8) Dry the membrane filter with the undissolved component attached at 50 ° C. for 3 hours.
9) The Nb residue rate is calculated from the following formula.
Nb residue ratio (%) = mass of filtration residue (g) ÷ charged mass of Nb raw material compound (g) × 100

  From the viewpoint of making the Nb residue ratio within a preferable range, the average particle size of the Nb raw material compound, preferably niobic acid is preferably 1.0 to 100 μm, more preferably 1.5 to 60 μm, and still more preferably 2.0. It is -40 micrometers, Most preferably, it is 2.0-20 micrometers. When the average particle size of the Nb raw material compound is 100 μm or less, the surface area per unit mass tends to be appropriately increased and the solubility tends to be further improved. On the other hand, when the average particle size is 1.0 μm or more, the surface area per unit mass is appropriately reduced, and the drying of the particle surface is facilitated. As a result, insoluble Nb oxide is formed on the particle surface. Can be suppressed, and the solubility tends to be further improved. In order to obtain an Nb raw material compound having good solubility, an Nb raw material compound having a large particle size may be classified using a sieve so as to appropriately fall within a desired average particle size range. In addition, an average particle diameter is measured based on the method as described in the below-mentioned Example.

Further, Nb starting compounds, preferably the specific surface area of niobate, preferable to be 20 to 300 m ² / g, more preferably from 30 to 200 m ² / g. When the specific surface area of the Nb raw material compound is within the above range, the Nb residue ratio can be easily controlled within a preferable range. The specific surface area is a specific surface area obtained by the BET method, that is, a method based on the BET adsorption isotherm (Brunauer-Emmett-Teller adsorption isotherm). For example, it is measured by a BET one-point method by nitrogen adsorption using a specific surface area measuring apparatus Gemini 2360 (product name, manufactured by Micromeritics, USA, import sales agency: Shimadzu Corporation, Japan).

  In addition, in order to make the Nb raw material compound, preferably niobic acid, easily dissolved in the Nb aqueous mixture, the niobic acid surface may be reduced in advance with ammonia or the like.

  The organic acid is not particularly limited, but at least one selected from the group consisting of dicarboxylic acids and anhydrides or hydrates thereof is preferable from the viewpoint of more effectively and reliably solving the problems of the present embodiment. From the same viewpoint, the dicarboxylic acid preferably has 2 to 6 carbon atoms (including carbon of a carboxyl group). Examples of dicarboxylic acids include oxalic acid, malonic acid, succinic acid, and glutaric acid. Among organic acids, oxalic acid anhydride and oxalic acid dihydrate are preferable from the viewpoint of suppressing the excessive reduction of the metal or metalloid oxide in the calcination step during catalyst production. An organic acid is used individually by 1 type or in combination of 2 or more types.

  The concentration of the organic acid in the Nb aqueous mixture is preferably 0.20 to 5.0 (mol-organic acid / kg-liquid), more preferably 0.20 to 4.5 (mol-organic acid / kg-). Liquid, and more preferably 0.20 to 4.0 (mol-organic acid / kg-liquid). When the concentration of the organic acid is 0.20 (mol-organic acid / kg-liquid) or more, the hardly soluble Nb raw material compound is hardly dissolved, so that filtration becomes easy and the solid content is uniformly dispersed. However, the Nb aqueous mixture having a smaller concentration distribution in the liquid tends to be obtained. On the other hand, when the organic acid concentration is 5.0 (mol-organic acid / kg-liquid) or less, the amount of dicarboxylic acid crystals generated in the cooling step described later can be reduced, and filtration is easy. In addition, there is a tendency that the blockage of the pipe is less likely to occur.

  The ratio of organic acid to niobium (organic acid / niobium) in the aqueous Nb mixture is preferably 3.0 to 6.0 in terms of molar ratio. When the organic acid / niobium molar ratio is 6.0 or less, the amount of organic acid deposited is suppressed, and the organic acid recovery rate tends to increase. In addition, the organic acid concentration in the obtained Nb aqueous mixture is kept low, the catalyst is prevented from being excessively reduced during the firing of the catalyst precursor described later, and the catalytic activity and the yield tend to be prevented from decreasing. . When the organic acid / niobium molar ratio is 3.0 or more, the solubility of the Nb raw material compound is increased, the precipitation of the niobium component after the cooling step is reduced, and the niobium recovery rate tends to be further increased.

  When the Nb raw material compound having good solubility of this embodiment, such as niobic acid, is used, the organic acid concentration in the Nb aqueous mixture tends to be lowered, the organic acid recovery rate is good, and the catalyst is fired at the time of firing the catalyst precursor. It becomes easy to prepare the reduction rate of the proper.

  Oxalic acid is used as the organic acid, the molar ratio of oxalic acid / niobium is 1.0 <oxalic acid / niobium <4.0, and the niobium concentration is 0.30 to 1.0 (mol-Nb / kg-solution). An example of a method for preparing an Nb aqueous mixture (dicarboxylic acid / Nb mixture) and an aqueous Nb organic acid solution that may be subsequently used, using an apparatus having a filter equipped with a jacket, will be described below.

  In order to adjust the hardly soluble niobium to a concentration of 0.30 (mol-Nb / kg-solution) or higher, the molar ratio of oxalic acid / niobium is set to be larger than 1.0 and the saturation concentration is taken into consideration. It is preferable to set the temperature at the time of preparing the Nb aqueous mixture and / or at the time of filtration. Although depending on the concentration of the mixture, when the niobium concentration is 0.30 to 1.0 (mol-Nb / kg-solution), oxalic acid and / or niobium should be added to the desired concentration or more by heating. It is preferable to adjust the concentration by dissolving a part or all of it and then lowering it to a temperature of an appropriate saturation concentration to precipitate a part of oxalic acid and / or niobium.

  In the following, an example of a method for preparing an aqueous Nb mixture using niobic acid as the Nb raw material compound so that the niobium concentration is 0.3 to 1.0 (mol-Nb / kg-solution) at 10 ° C will be described. To do.

  First, water is introduced into the mixing tank. Although there is no restriction | limiting in particular in the temperature of water, It is preferable that it is 10 to 70 degreeC. When the temperature of the water is 10 ° C. or higher, the raw materials oxalic acid and niobic acid are easily dissolved. When the water temperature is 70 ° C. or lower, it is possible to prevent the periphery of the inlet from getting wet with water vapor. Furthermore, a predetermined amount of niobic acid can be added more accurately. Next, niobic acid and oxalic acid are charged into the mixing tank. The temperature at which niobic acid or oxalic acid is charged into the mixing tank is not particularly limited, but is preferably 70 ° C. or lower for the same reason as described above. Further, the order of charging niobic acid and oxalic acid into the mixing tank is not particularly limited. However, from the viewpoint of preventing undissolved residue, it is preferable to add niobic acid and oxalic acid after adding water. The charged oxalic acid / niobium molar ratio may be 5.0, and the charged niobium concentration may be 0.520 (mol-Nb / kg-solution). A small amount of aqueous ammonia can also be added when they are suspended when they are introduced into the mixing tank.

  Next, the temperature of the liquid in the mixing tank is raised to 80 to 95 ° C. At this time, it is preferable that the rate of temperature increase is 1 ° C./hr from the viewpoint of preventing the progress of the decomposition of oxalic acid by increasing the time until the predetermined temperature is reached. Further, from the viewpoint of preventing oxalic acid from decomposing when the temperature exceeds 95 ° C., the temperature rising rate is preferably 30 ° C./hr or less. You may stir the liquid in a mixing tank as needed during temperature rising.

  Next, the liquid in the mixing tank is stirred while being heated so as to maintain the temperature in the range of 80 to 95 ° C., thereby obtaining an Nb aqueous mixture in which oxalic acid and the Nb raw material compound are dissolved. From the viewpoint of reducing undissolved niobium and preventing reprecipitation of niobium dissolved by complex formation with oxalic acid due to decomposition of oxalic acid, the heating and holding time is preferably 30 minutes to 4 hours. Thereafter, the Nb aqueous mixture is cooled to 40 ° C. or lower, and the temperature lowering rate at that time is preferably 0.002 ° C./min to 3 ° C./min. When the temperature lowering rate is 0.002 ° C./min or more, there is a tendency that niobium dissolved by complex formation with oxalic acid can be more effectively suppressed from reprecipitation due to decomposition of oxalic acid. On the other hand, when the temperature lowering rate is 3 ° C./min or less, precipitation of the dissolved niobium complex accompanying rapid cooling can be suppressed, and a more homogeneous liquid can be easily obtained and the niobium concentration in the liquid is reduced. It tends to be able to suppress a decrease in productivity due to the above. When setting to a desired niobium concentration in an Nb aqueous mixture at 10 ° C, the niobium concentration is adjusted by precipitating some oxalic acid or Nb components by setting the temperature of the Nb aqueous mixture to 30 ° C or lower. Is preferred. In that case, after cooling to 40 ° C or less, it may be kept at 30 ° C for several hours to wait for the precipitation of excess oxalic acid. It doesn't matter. By maintaining the temperature at 1 ° C. or higher, it is possible to prevent the water in the Nb aqueous mixture from freezing, and the variation in the concentration of each component in the Nb aqueous mixture tends to be further suppressed. Since the amount of oxalic acid dissolved can be suppressed by keeping it at 30 ° C. or lower, it is more effective that the oxalic acid concentration in the Nb aqueous mixture becomes high and it becomes difficult to adjust to the desired concentration. There is a tendency to prevent it. In order to start filtration after waiting for recrystallization of oxalic acid, it is preferable to hold for 30 minutes or more in a state where the liquid temperature is lowered. On the other hand, when the liquid is allowed to stand for 3 days or more, the crystals may solidify in the mixing tank and the inlet of the pipe connecting the mixing tank and the filter, which may cause clogging of the pipe. In the preparation process of the Nb aqueous mixture, the ratio of oxalic acid to niobium can be adjusted to a predetermined range by controlling the liquid temperature to be retained.

(Nb aqueous mixture filtration step)
The method for producing an oxide catalyst of the present embodiment preferably includes a step of filtering the Nb aqueous mixture to obtain an Nb organic acid aqueous solution. Specifically, it is preferable to have a step of supplying the Nb aqueous mixture to a filter and filtering under pressure. Thereby, solid content, such as the undissolved part of niobium in the aqueous Nb mixture, the undissolved part of the organic acid, and the precipitated part, can be removed.
From the viewpoint of efficiently filtering the Nb aqueous mixture and improving the productivity of the Nb organic acid aqueous solution from which undissolved components have been removed, it is preferable to filter under pressure. The pressure in that case is preferably 0.10 to 10 kg / cm ² (9.8 to 980 kPa) G from the viewpoint of productivity efficiency and pressure resistance of the filter paper.

  The filter paper to be used is preferably finer than 5 types A or more, for example, A No 3250 (model number) manufactured by Azumi Filter Paper Co., Ltd. can be used. A filtrate (an embodiment of an aqueous Nb organic acid solution) containing an organic acid (for example, dicarboxylic acid) and niobium in which the solid content thus obtained is uniformly dispersed and the concentration distribution in the liquid is small is obtained. It is withdrawn from the bottom of the container that receives the filtrate. The extracted Nb organic acid aqueous solution, which is the extracted liquid, is stored in a storage container adjusted to the same or close temperature as the liquid and used as a catalyst raw material. In addition, it is preferable to provide equipment capable of separating a part of the Nb organic acid aqueous solution while extracting the Nb organic acid aqueous solution. Furthermore, in case the ratio between the organic acid (for example, dicarboxylic acid) and niobium does not fall within the desired range, a pot connected to the container or storage container by piping and capable of introducing the organic acid and / or water is provided. It is preferable to use it. In order to adjust the ratio between the organic acid and niobium, an appropriate amount of organic acid and / or water is added to the pot, and then the organic acid and / or Nb organic acid aqueous solution is circulated between the pot and the storage container. Alternatively, water can be dissolved in an Nb organic acid aqueous solution to control the ratio of organic acid to niobium.

  Here, it is preferable to adjust the molar ratio (= X) of organic acid / Nb in the filtrate (Nb organic acid aqueous solution) to 1.0 <X <4.0. When X exceeds 1.0, precipitation of the Nb raw material compound (for example, niobic acid) tends to be more effectively suppressed, and when it is less than 4.0, an oxide is obtained using the obtained Nb organic acid aqueous solution. When preparing the catalyst, the catalyst performance tends to be more effectively prevented from deteriorating due to the catalyst being excessively reduced, particularly in the calcination step. From the same viewpoint, it is more preferable that 1.5 ≦ X ≦ 3.5.

  The concentration of the organic acid in the Nb organic acid aqueous solution is preferably 0.3 to 4.0 (mol-organic acid / kg-liquid), more preferably 0.40 to 3.8 (mol-organic acid / kg). -Liquid), more preferably 0.45 to 3.5 (mol-organic acid / kg-liquid). When the concentration of the organic acid is 0.3 (mol-organic acid / kg-liquid) or more, the precipitation of the Nb raw material compound (for example, niobic acid) tends to be more effectively suppressed. On the other hand, when the concentration of the organic acid is 4.0 (mol-organic acid / kg-liquid) or less, when preparing the oxide catalyst using the obtained aqueous Nb organic acid solution, the catalyst is used particularly in the firing step. There is a tendency that the deterioration of the catalyst performance due to the excessive reduction of the catalyst can be more effectively prevented.

In the filtration step, it is preferable to separate the solid content by filtration while pressurizing the Nb aqueous mixture at a pressure of 0.10 to 5.0 kg / cm ² (9.8 to 490 kPa) G. More preferably, cooling water is passed through a jacket provided outside the filter in order to keep the temperature of the filtrate at 10 to 15 ° C. during filtration. Thereby, solid content in a liquid becomes more uniform and transparent Nb organic acid aqueous solution can be obtained. When the organic acid is oxalic acid and the Nb raw material compound is niobic acid, the molar ratio of oxalic acid / niobium in this Nb organic acid aqueous solution can be analyzed as follows.

In the crucible, the Nb organic acid aqueous solution is dried at 50 to 100 ° C. overnight and then heat-treated at 300 to 800 ° C. for 1 to 10 hours. The amount of solid niobic acid (Nb ₂ O ₅ ) is obtained by subtracting the mass of the crucible from the total mass of the crucible and its contents after the heat treatment, and the niobium concentration is calculated from the result.

On the other hand, the oxalic acid concentration is calculated according to the following method. That is, 3 g of an Nb organic acid aqueous solution is precisely weighed and charged into a 300 mL glass beaker, 200 mL of hot water at about 80 ° C. is added, and then 10 mL of 1: 1 sulfuric acid is added. The mixed solution in the obtained beaker is titrated with 1 / 4N KMnO ₄ under stirring while maintaining the liquid temperature at 70 ° C. on a hot stirrer. The end point is a point where a faint light pink color by KMnO ₄ continues for about 30 seconds or more. The concentration of oxalic acid can be determined from the titration amount according to the following formula.
2KMnO ₄ + 3H ₂ SO ₄ + 5H ₂ C ₂ O ₄ → K ₂ SO ₄ + 2MnSO ₄ + 10CO ₂ + 8H ₂ O

  The obtained Nb organic acid aqueous solution can be used as a niobium raw material liquid in the production of an oxide catalyst, for example.

In the method for producing an oxide catalyst of the present embodiment, an oxide catalyst is prepared using an Nb aqueous mixture or an Nb organic acid aqueous solution (hereinafter simply referred to as “Nb aqueous mixture etc.”) obtained by the above-described method. It is preferable to prepare an oxide catalyst containing Mo, V, Sb and Nb.
An example in which the aqueous Nb mixture prepared by the above-described method is used for preparing an oxide catalyst containing niobium is shown below.

(Nb organic acid compound / complex forming agent aqueous solution preparation process)
In the method for producing an oxide catalyst according to the present embodiment, an Nb organic acid aqueous solution is mixed with a complexing agent or an aqueous solution of a complexing agent to obtain an Nb organic acid compound / complexing agent aqueous solution (Nb organic acid compound / complex It is preferable to have a step of preparing a forming agent aqueous solution. By having such a process, the complexing agent is coordinated to Nb, and the Nb organic acid can be present in a more stable dissolved state in the liquid, and precipitation can be prevented more effectively and reliably. However, in addition to or instead of this step, a step of obtaining an Nb organic acid compound / complexing agent aqueous solution by mixing an aqueous Nb mixture with a complexing agent or an aqueous solution of the complexing agent may be included.

  Examples of the complexing agent include, but are not limited to, hydrogen peroxide and monooxypolycarboxylic acid, and these are preferable from the viewpoint of easy coordination to Nb and stability of the formed complex. . The monooxy polyvalent carboxylic acid is a compound having one hydroxyl group and two or more carboxylic acid groups in one molecule. Examples of the monooxy polyvalent carboxylic acid include, but are not limited to, for example, tartronic acid, methyl Tartronic acid, ethyltartronic acid, n-propyltartronic acid, isopropyltartronic acid, oxymethylmalonic acid, oxyisopropylmalonic acid, ethyl-oxymethyl-malonic acid, DL-malic acid, L-malic acid, D -Malic acid, α-methylmalic acid, α-oxy-α'-methylsuccinic acid, α-oxy-α ', α'-dimethylsuccinic acid, α-oxy-α, α'-dimethylsuccinic acid, α-oxy -Α'-ethylsuccinic acid, α-oxy-α'-methyl-α-ethylsuccinic acid, trimethylmalic acid, α-oxyglutaric acid, β-oxyglu Phosphoric acid, dicrotalic acid, β-oxy-α, α-dimethylglutaric acid, β-oxy-α, α, γ-trimethylglutaric acid, β-oxy-α, α, β-trimethylglutaric acid, α-oxyadipine Acid, α-methyl-α-oxyadipic acid, α-oxysuberic acid, α-oxysebacic acid, 2-oxy-2-octyltetradecanedioic acid, citric acid, isocitric acid, 4-oxypentane-1,3, Examples include 4-tricarboxylic acid and norcaperate acid. Among these, citric acid, DL-malic acid, L-malic acid, and D-malic acid are preferable. As the complexing agent, hydrogen peroxide is particularly preferable.

  Prepared by reducing the precipitation of Nb, optimizing the stability of the Nb organic acid compound / complexing agent aqueous solution, and the oxidation-reduction state of the raw material mixture at the time of catalyst preparation using the Nb organic acid compound / complexing agent aqueous solution From the viewpoint of further improving the yield of the catalyst, the amount of the complexing agent used is preferably 0.2 to 10 and preferably 0.4 to 8.0 on a molar basis with respect to Nb. More preferred.

The raw material other than the Nb raw material compound is not particularly limited. For example, in addition to Mo, V and Sb, Y, Mn, W, B, Ti, Al, Si, which can be a metal or metalloid element constituting the catalyst, It may be a compound having Te, alkali metal, alkaline earth metal and rare earth metal. More specifically, the following compounds can be used. Examples of the Mo source compound (molybdenum compound) that can be included in the oxide catalyst include, but are not limited to, molybdenum oxide, ammonium dimolybdate, ammonium heptamolybdate, phosphomolybdic acid, and silicomolybdic acid. . Among these, ammonium heptamolybdate can be suitably used. Examples of the compound serving as the V source include, but are not limited to, vanadium pentoxide, ammonium metavanadate, and vanadyl sulfate. Among these, ammonium metavanadate can be preferably used. Furthermore, the compound serving as the Sb source is not particularly limited, but an antimony oxide can be preferably used.
These raw materials are used alone or in combination of two or more.

(Raw material preparation process)
It is preferable that the manufacturing method of the oxide catalyst of this embodiment has the raw material preparation process which prepares a catalyst raw material preparation liquid. In this step, a raw material preparation solution is obtained by dissolving and mixing a raw material having a compound of a metal or metalloid element in a solvent such as water. More specifically, the Nb organic acid compound / complex forming agent aqueous solution is one or two or more aqueous solutions containing a compound of a metal other than niobium or a metalloid element contained in the finally obtained oxide catalyst. Mix with the mixture to obtain a catalyst raw material preparation. Here, the Nb organic acid compound / complexing agent is used in the form of a mixture in which the aqueous mixture is mixed with an arbitrary component such as hydrogen peroxide for the purpose of improving the solubility of the above elements and adjusting the oxidation degree of the catalyst raw material preparation liquid. You may mix with aqueous solution. Thus, by obtaining a raw material preparation liquid, the effect of this embodiment can be more effectively and reliably produced.

Hereinafter, this process will be described more specifically with reference to an example of preparing a raw material preparation liquid containing Mo, V, Nb, and Sb.
First, each powder of a compound serving as a Mo source (for example, ammonium heptamolybdate), a compound serving as a V source (for example, ammonium metavanadate), and a compound serving as a Sb source (for example, diantimony trioxide) are added to water, A liquid aqueous mixture (hereinafter also referred to as “mixture (B)”) is prepared by heating to 80 ° C. or higher. At this time, for example, when the oxide catalyst contains Ce, a compound serving as a Ce source, for example, cerium nitrate may be added simultaneously.
Next, according to the target composition, the Nb organic acid compound / complex forming agent aqueous solution prepared previously and the mixture (B) are mixed to obtain a raw material preparation solution. For example, when the oxide catalyst contains W and / or Ce, it is preferable to obtain a raw material preparation liquid by mixing a compound serving as a W source. The compound that becomes the W source is not particularly limited as long as it is a compound having W, and examples thereof include ammonium metatungstate, which is preferably used. The compound serving as the Ce source is not particularly limited as long as it is a compound having Ce, and examples thereof include cerium nitrate hexahydrate, which is preferably used. The compound serving as the W source and / or the compound serving as the Ce source can be added to the mixture (B), or at the same time when the Nb organic acid compound / complexing agent aqueous solution and the mixture (B) are mixed. It can also be added. In the case where the metal or metalloid element oxide as described above is supported on a metalloid oxide support such as a silica support, a raw material preparation solution may be prepared so as to contain the oxide sol. In this case, the oxide sol can be appropriately added at any of the above timings. From the viewpoint of more effectively and reliably achieving the effects of the present embodiment, the support is preferably silica.

In addition, for the purpose of increasing the solubility of the metalloid and making the oxidation degree of the element in the catalyst raw material preparation liquid in a preferable state, the liquid containing the component of the mixture (B) or the mixture (B) in the middle of preparation is excessive. It is preferable to add hydrogen oxide (H ₂ O ₂ ). From the same viewpoint, when antimony is used as the metalloid element, it is particularly preferable to add hydrogen peroxide as described above. Further, from the same viewpoint, when hydrogen peroxide (H ₂ O ₂ ) is added to the liquid containing the components of the mixture (B) or the mixture (B) in the middle of preparation, H ₂ O ₂ / metalloid (molar ratio) is , Preferably it is 0.01-5, More preferably, it is 0.05-4. Moreover, after adding hydrogen peroxide, it is preferable to continue stirring at 30 ° C. to 70 ° C. for 30 minutes to 2 hours. The catalyst raw material preparation liquid thus obtained is usually a slurry, although the precipitation of solids is further suppressed and there may be a more uniformly dispersed liquid mixture.

(Drying process)
It is preferable that the manufacturing method of this embodiment has a drying process which dries a raw material preparation liquid and obtains a dried body. In the drying step, the raw material preparation liquid obtained in the above-described step is dried to obtain a dry powder. The method for drying the raw material preparation liquid may be a known method, for example, spray drying or evaporation to dryness, but it is preferable to obtain a microspherical dry powder by spray drying. The atomization in the spray drying is not particularly limited. For example, the atomization may be performed by a centrifugal method, a two-fluid nozzle method, or a high-pressure nozzle method. Although it does not specifically limit as a drying heat source, For example, the air heated with the steam, the electric heater, etc. can be used. In the case of using a spray dryer, the dryer inlet temperature is preferably 150 to 300 ° C. from the viewpoint of making the particle shape close to a sphere, making it preferable for wear resistance in a fluidized bed reaction, and the dryer outlet temperature. Is preferably 100 to 160 ° C.

(Baking process)
It is preferable that the manufacturing method of this embodiment has a baking process which bakes the dry body obtained through the drying process. In the firing step, the dried product obtained in the drying step, preferably a dry powder, is fired to obtain an oxide catalyst.
(Dry powder firing method)
Although it does not specifically limit as a baking apparatus, For example, a rotary furnace (rotary kiln) can be used. The shape of the calciner is not particularly limited, but a tubular shape (firing tube) is preferable from the viewpoint of continuous firing, and a cylindrical shape is particularly preferable. The heating method is preferably an external heating type from the viewpoint of easy adjustment of the firing temperature so as to have a preferable temperature rising pattern, and an electric furnace can be suitably used. As the size and material of the firing tube, an appropriate one can be selected according to the firing conditions and the production amount. The inner diameter of the calcining tube is preferably 70 to 2000 mm, more preferably 100 to 1700 mm from the viewpoint of reducing the unevenness of the calcining temperature distribution in the catalyst layer as much as possible, adjusting the calcining time and the production amount to appropriate values, and the like. is there. The length of the calcining tube is such that the residence time of the dry powder and catalyst precursor particles in the calcining tube, that is, the distribution of the calcining time is narrowed as much as possible, the distortion of the calcining tube is prevented, the calcining time and the production amount are appropriate. From the viewpoint of adjusting to a value, etc., it is preferably 200 to 10000 mm, more preferably 800 to 8000 mm. When an impact is applied to the fired tube, the thickness is preferably 2 mm or more, more preferably 4 mm or more, from the viewpoint of having a sufficient thickness that does not damage the fired tube. Further, from the viewpoint that the impact is sufficiently transmitted to the inside of the firing tube, the thickness is preferably 100 mm or less, more preferably 50 mm or less. Also, from the viewpoint of reducing the unevenness of the firing temperature distribution and the firing time distribution in the catalyst layer as much as possible, adjusting the firing time and the production amount of the catalyst to appropriate values, etc., the firing tube is in the direction in which the powder flows. It is preferable to have an inclination and to make the height of the outlet lower than the height of the powder inlet. From the same viewpoint, the inclination angle θ from the horizontal is preferably 0 ° <θ <80 °, and more preferably 1 ° ≦ θ ≦ 40 °.
The material of the calciner is not particularly limited as long as it is preferably heat-resistant and has a strength that does not break due to impact. For example, SUS can be suitably used.

It is also possible to divide the calcining tube into two or more areas by providing a weir plate in the calcining tube that has a hole in the center for allowing the powder to pass vertically (or substantially perpendicular) to the powder flow. . By installing the weir plate, it becomes easy to ensure the residence time of the powder in the firing tube. The number of weir plates may be one or more. From the viewpoint of improving the durability and heat resistance to the firing atmosphere, the material of the barrier plate is preferably a metal, and the same material as the firing tube can be suitably used. The height of the weir plate can be adjusted according to the residence time to be secured. For example, when a dry powder is supplied at 250 g / hr using a rotary furnace having a 150 mm inner diameter and a 1150 mm long SUS firing tube, the height of the weir plate is preferably 5 to 50 mm, more preferably 10 to 40 mm. More preferably, it is 13 to 35 mm. The thickness of the weir plate is not particularly limited and is preferably adjusted according to the size of the firing tube. For example, in the case of a rotary furnace having a SUS firing tube having an inner diameter of 150 mm and a length of 1150 mm, the thickness of the barrier plate is preferably 0.3 mm or more and 30 mm or less, more preferably 0.5 mm or more and 15 mm or less.
In order to prevent cracking, cracking, and the like of the dry powder and to perform uniform firing, it is preferable to perform firing while rotating the firing tube around its length direction. The rotation speed of the firing tube is preferably 0.1 to 30 rpm, more preferably 0.5 to 20 rpm, and still more preferably 1 to 10 rpm.

In the calcination of the dry powder, from the viewpoint of bringing the obtained catalyst into a preferable redox state, improving the catalyst performance, etc., the heating temperature of the dry powder is started from a temperature lower than 400 ° C. It is preferable to raise the temperature continuously or stepwise to a temperature in the range of 800 ° C.
The firing atmosphere may be an air atmosphere or an air flow, but from the viewpoint of easy adjustment of the catalyst to a preferred redox state, at least a part of the firing is an inert gas substantially free of oxygen such as nitrogen. It is preferable to carry out while distributing.

  In the case of performing the baking in a batch system, from the viewpoint of adjusting to a preferable redox state, the supply amount of the inert gas is preferably 50 Nl / hr or more, more preferably 50 to 5000 Nl / hr, per 1 kg of the dry powder. More preferably, it is 50 to 3000 N liter / hr. Here, “N liter” means a liter measured at standard temperature and pressure conditions, that is, 0 ° C. and 1 atmosphere.

  When firing is performed continuously, the supply amount of the inert gas is preferably 50 N liter / hr or more, more preferably 50 to 5000 N liter / hr, per 1 kg of the dry powder from the viewpoint of adjusting to a preferable redox state. More preferably, it is 50 to 3000 N liter / hr. At this time, the contact form of the inert gas and the dry powder may be a counter-current contact or a co-current contact, but in consideration of the gas component generated from the dry powder and the air that can be mixed in a small amount in the dry powder. Flow contact is preferred. In particular, in the above-described Nb organic acid compound / complex forming agent aqueous solution preparation step or raw material preparation step, a method in which hydrogen peroxide is mixed with the aqueous mixture (B) is employed, and molybdenum and vanadium are liquidized to a maximum oxidation number. In the case of obtaining the raw material preparation liquid by oxidizing in the inside, it is preferable to calcinate the dry powder while circulating an inert gas substantially free of oxygen such as nitrogen.

  The dry powder usually may contain ammonium root, organic acid, inorganic acid, etc. in addition to moisture.

When calcining dry powder while circulating an inert gas that does not substantially contain oxygen, when the dry powder and catalyst precursor evaporate, decompose, etc., the metal or metalloid elements contained therein are reduced. Is done.
When the element of the metal or metalloid in the dry powder has almost the highest oxidation number, in order to bring the reduction rate of the oxide catalyst into the desired range, it is only necessary to carry out the reduction in the calcination step. Is simple.
On the other hand, as will be described later, an oxidizing component or a reducing component may be added to the firing atmosphere so that the reduction rate falls within a desired range. Firing is preferably carried out so that the reduction rate of the resulting oxide catalyst is 8 to 12% and the specific surface area is 5 to 30 m ² / g. When the specific surface area of the catalyst is 5 to 30 m ² / g, more sufficient activity is obtained, deterioration is further suppressed, and the yield tends to be further increased. In addition, with respect to the addition effect of the molybdenum compound for maintaining the yield during the oxidation reaction or ammoxidation reaction, the effect is more fully exhibited and does not show sharp deterioration. Tends to be further reduced. Although the reason for this is not clear, it is presumed that when the specific surface area is less than 5 m ² / g, the active surface of the active species that controls the reaction is also small, and it is difficult to exert the effect of adding the molybdenum compound. Moreover, when the specific surface area is larger than 30 m ² / g, it is presumed that the active surface of the active species becomes large, while the escape of molybdenum from the active surface becomes fast. The reduction rate of the oxide catalyst and the catalyst precursor is calculated by the following formula (6).
Reduction rate (%) = ((n ₀ −n) / n ₀ ) × 100 (6)
Here, in Formula (6), n is the number of oxygen atoms that satisfy the valence of the constituent element other than oxygen in the oxide catalyst or catalyst precursor, and n ₀ is other than oxygen in the oxide catalyst or catalyst precursor. Is the number of oxygen atoms required when each of the constituent elements has the highest oxidation number.

In obtaining the reduction rate, the value of (n ₀ −n) in the above formula (6) is obtained by performing oxidation-reduction titration of the sample with KMnO ₄ . In addition, the value of (n ₀ −n) can be determined by oxidation-reduction titration for both the catalyst precursor before the end of firing and the oxide catalyst after the end of firing. However, in the measurement by oxidation-reduction titration, the measurement conditions are different between the catalyst precursor before the end of calcination and the catalyst after the end of calcination. An example of a measurement method is shown below for each of the catalyst precursor before the calcination and the catalyst after the calcination.

For the catalyst precursor before the end of calcination, for example, the reduction rate is measured as follows.
First, about 200 mg of a sample is accurately weighed in a beaker. An excessive amount of a KMnO ₄ aqueous solution having a known concentration is added thereto. Next, 150 mL of pure water at 70 ° C. and 2 mL of 1: 1 sulfuric acid (that is, a sulfuric acid aqueous solution obtained by mixing concentrated sulfuric acid and water at a volume ratio of 1/1) were added to the beaker, and then the opening of the beaker Is closed with a watch glass, and the liquid in the beaker is stirred in a hot water bath at 70 ° C. ± 2 ° C. for 1 hour to oxidize the sample. At this time, KMnO ₄ is excessively present, and since unreacted KMnO ₄ is present in the liquid, it is confirmed that the liquid color is purple. Next, after the oxidation is completed, filtration is performed with a filter paper, and the entire filtrate is recovered. Next, an aqueous solution of sodium oxalate (Na ₂ C ₂ O ₄ ) having a known concentration is added so as to be excessive with respect to KMnO ₄ present in the filtrate, and the liquid temperature is adjusted to 70 ° C. thereafter. Stir to heat. After confirming that the liquid became colorless and transparent, 2 mL of 1: 1 sulfuric acid was added thereto. Further, stirring is continued while maintaining the liquid temperature at 70 ° C. ± 2 ° C., and titration is performed with a KMnO ₄ aqueous solution having a known concentration. The end point is a point where the liquid color becomes faint light pink by titration with KMnO ₄ and continues for about 30 seconds. From the total amount of KMnO ₄ and the total amount of Na ₂ C ₂ O _{4, the} amount of KMnO ₄ consumed for the oxidation of the sample is determined. From this amount of KMnO ₄ , (n ₀ −n) is calculated, and the reduction rate is obtained based on this.

About the oxide catalyst after completion | finish of baking, a reduction rate is measured as follows, for example.
First, in a beaker, about 200 mg of the catalyst crushed in a mortar made of agate is precisely weighed. Thereto is added 150 mL of 95 ° C. pure water and 4 mL of 1: 1 sulfuric acid (that is, an aqueous sulfuric acid solution obtained by mixing concentrated sulfuric acid and water at a volume ratio of 1/1). Next, the mixture is stirred while maintaining the liquid temperature at 95 ° C. ± 2 ° C., and titrated with a KMnO ₄ aqueous solution having a known concentration. At this time, although the liquid color is temporarily purple by KMnO ₄ dropwise, so purple does not continue for more than 30 seconds, dropping the KMnO ₄ portionwise slowly. Further, since the amount of liquid is reduced by evaporation of water, pure water at 95 ° C. is added as needed so that the amount of liquid becomes constant. The end point is a point where the liquid color becomes faint light pink by titration with KMnO ₄ and continues for about 30 seconds. In this way, the amount of KMnO ₄ consumed for the oxidation of the sample is obtained. From this amount of KMnO ₄ , (n ₀ −n) is calculated, and the reduction rate is obtained based on this.

In addition to the above-described measurement method, both the catalyst precursor before the end of calcination and the oxide catalyst after the end of calcination can be measured as follows.
That is, the sample is completely oxidized with oxygen by heating the sample to a temperature higher than the firing temperature at which the catalyst precursor or catalyst was calcined under conditions where the constituent elements of the sample do not volatilize and escape and in an oxygen-containing atmosphere. Then, the increased mass (amount of bound oxygen) is obtained, and the value of (n ₀ −n) is obtained from this, and the reduction rate is obtained based on this.

In the dry powder firing method, specifically, the dry powder is fired. At this time, the heating temperature of the dry powder starts from a temperature lower than 400 ° C., and is 550 to 700 ° C. Calcination is performed under calcination conditions where the temperature is raised continuously or stepwise to a temperature within the range, and the reduction rate of the catalyst precursor during calcination is 8 to 12% when the heating temperature reaches 400 ° C. It is preferable to adjust the conditions.
For the reduction rate of the oxide catalyst, generally, the amount of organic components such as oxalic acid contained in the dry powder, the amount of ammonium root derived from the raw material ammonium salt, the rate of temperature rise at the start of firing In the case of firing in an inert gas atmosphere, the amount of the inert gas is affected. In the case of firing in an air atmosphere, the temperature and time are affected.
In order to set the reduction rate of the oxide catalyst to 8 to 12%, for example, at the time of calcination, the temperature rise is started from a temperature lower than 400 ° C. to decompose oxalate root, ammonium root, etc. in the dry powder. There is a method in which gas generation is almost finished and the reduction rate of the catalyst precursor during calcination when the heating temperature reaches 400 ° C. is 8 to 12%.

The specific surface area of the catalyst is affected by the temperature and time at which the catalyst is finally fired (heated) and the amount of the carrier supported when the catalyst is supported on a carrier such as silica, but when the heating temperature reaches 400 ° C. The reduction rate and final calcination temperature are particularly greatly affected. From this viewpoint, the final firing temperature is preferably 550 ° C. to 700 ° C., and the firing time at that temperature is preferably 0.5 hours to 20 hours. The specific surface area tends to be smaller as the final firing temperature is higher and the firing time is longer.
Moreover, since the reduction rate when the heating temperature reaches 400 ° C. is in the range of 8 to 12%, the specific surface area of the catalyst tends to be prevented from becoming excessively small or large.
For example, in order to set the specific surface area of the catalyst to 5 to 30 m ² / g, the reduction rate when the heating temperature reaches 400 ° C. is within the range of 8 to 12%, and the final calcination temperature is 550. It is preferable that the temperature is from 700C to 700C.

Calcination may be carried out in one stage with constant conditions, but in order to efficiently obtain an oxide catalyst having a reduction rate of 8 to 12% and a specific surface area of 5 to 30 m ² / g, It is preferable that the calcination includes pre-stage calcination and main calcination performed thereafter. Here, the firing temperature in the pre-stage firing is preferably lower than the firing temperature in the main firing, and more specifically, the pre-stage firing is performed in a temperature range of 250 to 400 ° C., and the main firing is performed at 550 to 700 ° C. It is preferable to carry out in the temperature range. A pre-baked powder is obtained by the pre-baking, and a main-baked powder is obtained by the main baking.
The main calcination may be performed continuously after the pre-stage calcination, that is, by directly changing the calcination temperature in the pre-stage calcination from the calcination temperature in the main calcination. The temperature may be lowered once from the temperature and then heated to the firing temperature in the main firing. In addition, each of the pre-stage firing and the main firing may be divided into a plurality of firing stages having different firing conditions.

When measuring the reduction rate of the catalyst precursor during calcination, the sample may be taken out from the calcination apparatus at that temperature, but at a high temperature, it may be oxidized by contact with air and the reduction rate may change. Therefore, the sample taken out from the baking apparatus after cooling to room temperature may be used as a representative sample.
As a method for controlling the reduction rate when the heating temperature reaches 400 ° C. to a desired range, specifically, a method for adjusting the firing temperature in the pre-stage firing, an oxidizing component such as oxygen in the atmosphere during firing And a method of adding a reducing component to the atmosphere during firing. Moreover, you may combine 2 or more types of methods among these.

  The method of changing the calcination temperature in the pre-stage calcination (hereinafter referred to as “pre-stage calcination temperature”) is to adjust the reduction rate of the catalyst precursor when the heating temperature reaches 400 ° C. by changing the pre-stage calcination temperature. It is a technique to do. Usually, the reduction rate decreases when the pre-stage calcination temperature is lowered, and the reduction rate tends to increase when the pre-stage calcination temperature is raised. Therefore, the reduction rate can be controlled by changing the pre-stage calcination temperature.

The method of adding an oxidizing component such as oxygen to the atmosphere at the time of firing is a method that can be used when reducing the reduction rate of the catalyst precursor when the heating temperature reaches 400 ° C. Here, “during firing” may be pre-stage firing, main firing, or both firing.
The oxidizing component added to the atmosphere during firing is the oxidizing component in the inert gas supplied to the firing apparatus, and the amount of the oxidizing component added depends on the concentration in the inert gas supplied to the firing apparatus. Can manage. By adding this oxidizing component, the reduction rate of the catalyst precursor when the heating temperature reaches 400 ° C. can be controlled. When the oxidizing component is oxygen, air (or an inert gas containing air) can be supplied to the calcining apparatus, and oxygen in the air can be used as the oxidizing component.

The method of adding a reducing component to the atmosphere during firing is a method that can be used to increase the reduction rate of the catalyst precursor when the heating temperature reaches 400 ° C. Here, “during firing” may be pre-stage firing, main firing, or both firing.
The reducing component added to the atmosphere during firing is the reducing component in the inert gas supplied to the firing device, and the amount of the reducing component added depends on the concentration in the inert gas supplied to the firing device. Can manage. By adding this reducing component, the reduction rate of the catalyst precursor when the heating temperature reaches 400 ° C. can be controlled. Although it does not specifically limit as a reducing component, For example, ammonia can be used.

  In addition, when the reduction rate of the catalyst precursor when the heating temperature reaches 400 ° C. is not a desired reduction rate, the difference between the actual reduction rate and the desired reduction rate causes the necessary oxidizing component or reducing component to be reduced. The total amount can be calculated and added to the atmosphere during firing.

  A method for making the firing atmosphere in an inert gas or a preferable oxidizing / reducing atmosphere is not particularly limited, but a firing device having an appropriate seal structure and capable of sufficiently blocking contact with the outside air should be used. preferable.

The pre-stage calcination is preferably performed under an inert gas flow, preferably the pre-stage calcination temperature is 250 ° C. to 400 ° C., more preferably, from the viewpoint that the obtained catalyst can be easily adjusted to a preferable redox state and the catalyst performance can be improved. It is performed in the range of 300 ° C to 400 ° C. Although it is preferable to maintain the pre-stage firing temperature at a constant temperature within a temperature range of 250 ° C. to 400 ° C., even if the temperature fluctuates within a range of 250 ° C. to 400 ° C., or the temperature is gradually raised or lowered. Good. The holding time of the heating temperature is preferably 30 minutes or more, more preferably 3 to 12 hours, from the viewpoint of easy adjustment of the obtained catalyst to a preferable redox state and improvement of catalyst performance. The temperature pattern until reaching the pre-stage firing temperature may be a linear temperature rising pattern, or may be a temperature rising pattern that draws an upward or downward convex arc. Further, there may be a time for the temperature to drop during the temperature rise, and the temperature rise and the temperature fall may be repeated. Furthermore, an endothermic reaction may occur due to components contained in the dry powder and / or catalyst precursor during the temperature raising process, and the temperature may be temporarily lowered.
There is no particular limitation on the average rate of temperature increase at the time of temperature increase until reaching the pre-stage calcination temperature. It may be about -15 ° C / minute, preferably 0.5-5 ° C / minute, more preferably 1-2 ° C / minute.

  From the viewpoints of easily adjusting the obtained catalyst to a preferable specific surface area, sufficiently forming a crystal structure active in reaction, improving catalyst performance, etc., the main calcination is preferably performed under an inert gas flow, preferably a calcination temperature. Is carried out at 550 to 800 ° C, more preferably 580 to 750 ° C, still more preferably 600 to 720 ° C, particularly preferably 620 to 700 ° C. The firing temperature is preferably maintained at a constant temperature within the temperature range of 550 to 800 ° C., but the temperature may vary within the range of 550 to 800 ° C., or the temperature may be gradually increased or decreased. Further, the temperature may be temporarily lowered by an endothermic reaction, there may be a time for the temperature to be lowered during the temperature increase, and the temperature increase and the temperature decrease may be repeated as in the pre-stage firing. Also, from the viewpoints of easily adjusting the obtained catalyst to a preferred specific surface area, easily forming a crystal structure active in reaction, and improving catalyst performance, the firing time of the main firing (holding time at the firing temperature) Is preferably 0.5 to 20 hours, more preferably 1 to 15 hours. The temperature rising pattern until reaching the firing temperature may be a linear temperature rising pattern, or may be a temperature rising pattern that draws an upward or downward convex arc. In addition, there is no particular limitation on the average temperature increase rate at the time of temperature increase until reaching the calcination temperature, but it is easy to adjust the obtained catalyst to a preferable specific surface area, and a catalyst that can easily form a crystal structure active for reaction sufficiently. From the viewpoint of improving the performance, it may be, for example, 0.1 to 15 ° C./min, preferably 0.3 to 10 ° C./min, more preferably 0.5 to 8 ° C./min.

  The main calcination is preferably performed at 550 to 800 ° C., preferably 580 to 750 ° C., more preferably 600 to 720 ° C., and still more preferably 620 to 700 ° C. under an inert gas flow. Although it is preferable to hold at a constant temperature within a temperature range of 620 to 700 ° C., the temperature may fluctuate within the range of 620 to 700 ° C., or the temperature may be gradually increased or decreased. The firing time is 0.5 to 20 hours, preferably 1 to 15 hours. When the calcining tube is separated by a dam plate, the dry powder and / or oxide catalyst passes continuously through at least two, preferably 2-20, more preferably 4-15 zones. The temperature can be controlled by using one or more controllers, but in order to obtain the desired firing pattern, a heater and a controller can be installed and controlled for each section separated by these weirs. preferable. For example, when using seven calcining tubes that are divided into eight sections and the length of the portion of the calcining tube that enters the heating furnace is divided into eight equal parts, dry powder and / or oxide catalyst It is preferable that the set temperature is controlled by a heater and a controller in which eight areas are provided for each of the areas so that the temperature becomes the desired firing temperature pattern. If desired, an oxidizing component (for example, oxygen) or a reducing component (for example, ammonia) may be added to the firing atmosphere under an inert gas flow.

  The temperature rising pattern until reaching the main firing temperature may be increased linearly, or the temperature may be increased by drawing an upward or downward convex arc.

  There is no particular limitation on the average rate of temperature increase during the temperature increase until the main firing temperature is reached, but generally 0.1 to 15 ° C./min, preferably 0.5 to 10 ° C./min, more preferably 1 to 8 ° C / min.

  The average temperature drop rate after the completion of the main firing is preferably 0.05 to 100 ° C./min, more preferably 0.1 to 50 ° C./min. Moreover, it is also preferable to hold once at a temperature lower than the main firing temperature. The temperature to be maintained is 10 ° C., preferably 50 ° C., more preferably 100 ° C. lower than the main firing temperature. The holding time is 0.5 hours or more, preferably 1 hour or more, more preferably 3 hours or more, and further preferably 10 hours or more.

  When the main baking is performed again after the pre-stage baking is once completed, it is preferable to perform a low temperature treatment in the main baking.

  The time required for low-temperature treatment, that is, the time required for raising the temperature to the firing temperature after reducing the temperature of the dry powder and / or oxide catalyst is the size, thickness, material, catalyst of the calciner It is possible to adjust appropriately according to the production amount, a series of periods in which the dried powder and / or the composite oxide catalyst are continuously fired, the fixing speed, the fixing amount, and the like. For example, in the case of using a SUS calcining tube having an inner diameter of 500 mm, a length of 4500 mm, and a wall thickness of 20 mm, preferably within 30 days, more preferably within 15 days, Preferably within 3 days, particularly preferably within 2 days.

  For example, dry powder is supplied at a rate of 35 kg / hr while rotating at 6 rpm by a rotary furnace having a SUS firing tube having an inner diameter of 500 mm, a length of 4500 mm, and a wall thickness of 20 mm, and the main firing temperature is set to 645 ° C. In this case, after the temperature is lowered to 400 ° C., the step of raising the temperature to 645 ° C. can be performed in about one day. In the case of continuous firing for one year, by performing such a low-temperature treatment at a frequency of once a month, there is a tendency that firing can be performed more stably while maintaining the oxide layer temperature.

In addition, if an impact is applied to the firing device in the firing process, the effect of causing cracks in the fixed mass tends to increase.When performing a low temperature treatment, if an impact is applied to the firing device, the crack is caused. The resulting lump is preferred because it tends to easily peel off from the calciner.
The magnitude of impact applied to the calciner is the powder depth of the dry powder and / or catalyst precursor supplied into the calciner, the diameter, length, thickness and material of the calciner, the material of the device that applies the impact, Since it depends on the type, shape and position, the frequency of impact, etc., it is preferable to set appropriately according to these.

  The method for applying the impact is not particularly limited, and an air knocker, hammer, hammering device, or the like can be preferably used. The material of the portion directly in contact with the firing device at the tip of the impact is not particularly limited as long as the material has sufficient heat resistance. For example, a general resin and metal that can withstand impact can be used. Metal is preferred. The metal preferably has a hardness that does not damage or deform the calciner, and can be suitably made of copper or SUS. The location to which the impact is applied is not particularly limited and can be performed at a location convenient for operation. However, since the impact can be directly applied to the calciner without waste, it is applied to the location not covered with the heating furnace of the calciner. It is preferable.

[Oxide catalyst]
Examples of the oxide catalyst obtained by the above production method include compounds represented by the following general formula (1). This oxide catalyst preferably has W in addition to Mo, V, Sb, and Nb from the viewpoint of more effectively and reliably achieving the effects of the present embodiment.
_{Mo 1 V a Nb b Sb c} Y d O n (1)
(Wherein Y represents at least one element selected from Mn, W, B, Ti, Al, Te, alkali metal, alkaline earth metal and rare earth metal, and a, b, c, d and n Indicates the atomic ratio of V, Nb, Sb, Y per molybdenum (Mo) atom, respectively, 0.1 ≦ a ≦ 1, 0.01 ≦ b ≦ 1, 0.01 ≦ c ≦ 1, 0 ≦ d ≦ 1, and n represents the number of oxygen atoms determined by the valence of a constituent element other than oxygen.)

  The atomic ratios a, b, c, and d per Mo atom are 0.1 ≦ a ≦ 1, 0.01 ≦ b ≦ 1, 0.01 ≦ c ≦ 1, and 0 ≦ d ≦ 1, respectively. Preferably, 0.1 ≦ a ≦ 0.5, 0.01 ≦ b ≦ 0.5, 0.1 ≦ c ≦ 0.5, 0.0001 ≦ d ≦ 0.5 are more preferable. More preferably, 2 ≦ a ≦ 0.3, 0.05 ≦ b ≦ 0.2, 0.2 ≦ c ≦ 0.3, and 0.0002 ≦ d ≦ 0.4.

When the catalyst is used in a fluidized bed, more sufficient strength is required, so that the oxide catalyst is preferably supported on silica. The oxide catalyst supported on silica is preferably 10 to 80% by mass, more preferably 20 in terms of SiO ₂ with respect to the total mass of the metal or metalloid element oxide and silica contained in the oxide catalyst. It is supported on silica of ˜60 mass%, more preferably 30 to 55 mass%. The amount of silica as a support is the total mass of the oxide of the metal or metalloid element and silica from the viewpoint of strength and prevention of powdering, ease of stable operation when using the catalyst, and reduction of replenishment of the lost catalyst. It is preferable that it is 10 mass% or more with respect to. Further, from the viewpoint of achieving sufficient catalytic activity, the content is preferably 80% by mass or less based on the total mass of the metal or metalloid element oxide and silica. In particular, when the catalyst is used in a fluidized bed, if the amount of silica is 80% by mass or less, the specific gravity of the oxide catalyst that is a silica-supported catalyst is appropriate, and a better fluidized state is likely to be formed.

(Flow inhibitor removal process)
The oxide catalyst thus produced may contain a flow inhibitor (protrusion) protruding from the particle surface. The flow inhibitor is formed in the shape of protrusions and / or protrusions on the surface of the oxide catalyst, and the oxide catalyst having the flow inhibitor does not exhibit sufficient fluidity when used in a fluidized bed reaction. In some cases, the yield of the target product is low as compared with those having no body. Therefore, it is preferable to remove the flow inhibitor from the catalyst so that it is 2% by mass or less based on the mass of the oxide catalyst.
As a method for removing the flow inhibitor, a method of removing the flow inhibitor by contacting the catalysts with each other under a gas flow is preferable. More specifically, there are a method of circulating a gas to a hopper or the like for storing the catalyst, and a method of storing an oxide catalyst in a fluidized bed reactor and flowing the gas therethrough. When a fluidized bed reactor is used, a special apparatus for removing the flow inhibitor is not necessary. When gas is circulated through a device such as a fluidized bed reactor filled with an oxide catalyst, the oxide catalysts come into contact with each other, and the protruding flow inhibitor is removed. Since the flow inhibitor separated from the oxide catalyst is much smaller than the spherical oxide catalyst, it flows out of the system together with the flowing gas.

Oxide in a container such as a hopper or a fluidized bed reactor in which an oxide catalyst is accommodated when removing the flow inhibitor from the viewpoint of efficiently removing the flow inhibitor and bringing the catalyst into contact with each other in a preferable state. It is preferable to remove the flow inhibitor so that the density of the catalyst is 300 to 1300 kg / m ³ . Further, the cross-sectional area orthogonal to the gas phase flow direction of the container is preferably from 0.1 to 0.1% in view of making the contact between the catalysts preferable, adjusting the removal amount of the flow inhibitor to a preferable value, and the like. 100 m ^2, more preferably 0.2~85m ^2. As the gas flowing in order to flow the catalyst in the container, an inert gas such as nitrogen and air are preferable from the viewpoint of not adversely affecting the catalyst. The gas linear velocity of the gas in the container is preferably 0.03 m / sec to 5 m / sec from the viewpoint of efficiently removing the flow inhibitor and making the contact between the catalysts preferable. Preferably it is 0.05-1 m / sec. The gas circulation time is preferably 1 to 50 hours.

[Production method of unsaturated acid and unsaturated nitrile]
In the method for producing an unsaturated acid according to the present embodiment, an unsaturated acid is produced by bringing an alkane such as propane or isobutane into contact with the oxide catalyst obtained by the above production method and reacting with molecular oxygen in a gas phase. It is a method to do. Thereby, a corresponding unsaturated acid (acrylic acid or methacrylic acid) can be produced from propane or isobutane.

  The method for producing an unsaturated nitrile according to the present embodiment is obtained by bringing an alkane such as propane or isobutane into contact with the oxide catalyst obtained by the above production method and reacting with ammonia and molecular oxygen in a gas phase. It is a method of manufacturing. Thereby, a corresponding unsaturated nitrile (acrylonitrile or methacrylonitrile) can be produced from an alkane such as propane or isobutane.

  The feedstock for alkanes such as propane or isobutane and ammonia need not be highly pure, and industrial grade gases can be used. As the supply oxygen source, air, pure oxygen, or air enriched with pure oxygen can be used. Furthermore, helium, neon, argon, carbon dioxide gas, water vapor, nitrogen or the like may be supplied as a dilution gas.

  In the case of an ammoxidation reaction, the molar ratio of ammonia supplied to the reaction system to alkane such as propane or isobutane is preferably 0.3 to 1.5, more preferably 0.8 to 1.2. In both the oxidation reaction and the ammoxidation reaction, the molar ratio of molecular oxygen supplied to the reaction system to alkane such as propane or isobutane is preferably 0.1 to 6, and more preferably 0.1 to 4.

  For both the oxidation reaction and the ammoxidation reaction, the reaction pressure is preferably 0.5 to 5 atm, more preferably 1 to 3 atm, and the reaction temperature is preferably 350 ° C to 500 ° C, more preferably 380 ° C to It is 470 degreeC, Preferably contact time is 0.1-10 (sec * g / cc), More preferably, it is 0.5-5 (sec * g / cc).

In the present embodiment, the contact time is defined by the following equation.
Contact time (sec · g / cc) = (W / F) × 273 / (273 + T) × P
here,
W = mass of catalyst (g),
F = flow rate of raw material mixed gas (Ncc / sec) in a standard state (0 ° C., 1 atm),
T = reaction temperature (° C.)
P = reaction pressure (atm).
The alkane conversion rate such as propane or isobutane and the unsaturated acid or unsaturated nitrile yield follow the following definitions, respectively.
Alkane conversion (%) = (number of moles of reacted alkane) / (number of moles of supplied alkane) × 100
Unsaturated acid or unsaturated nitrile yield (%) = (number of moles of unsaturated acid or unsaturated nitrile produced) / (number of moles of supplied alkane) × 100

  As the reaction method, a conventional method such as a fixed bed, a fluidized bed, or a moving bed can be adopted. However, heat removal from the reaction heat is easy and the temperature of the catalyst layer can be maintained almost uniformly, and the catalyst is extracted from the reactor during operation. The fluidized bed reaction is preferable because it is possible to add a catalyst.

In the present embodiment, the niobium recovery rate (%) is defined by the following equation.
Recovery rate = (water in filtrate + amount of niobic acid in filtrate) / (amount of water charged + amount of niobic acid added) × 100

  According to this embodiment, a method for producing an oxide catalyst used for a gas phase catalytic oxidation reaction or a gas phase catalytic ammoxidation reaction containing Nb, wherein the solubility of Nb during the production is good, It is possible to realize a manufacturing method that can be manufactured efficiently with high productivity.

  Hereinafter, the present embodiment will be described in more detail by way of examples, but the present embodiment is not limited to these examples.

(Particle size measurement method)
The particle size distribution was measured with a laser diffraction / scattering particle size distribution measuring device (trade name “LS230” manufactured by Beckman Coulter, Inc.), and the volume average was taken as the average particle size. Distilled water was used as the dispersion medium, the refractive index of distilled water was 1.33, the refractive index of the sample was 1.6, and calculation was performed using the pls model.

Example 1
Composition formula _{Mo 1 V 0.24 W 0.04 Nb 0.11} Sb 0.26 Ce 0.005 O n /48.0 wt% -SiO ₂ (SiO ₂ carrier. Hereinafter the same.) The oxide catalyst represented by was prepared as follows .
(Preparation of Nb aqueous mixture)
An Nb aqueous mixture was prepared by the following method. The Nb residue ratio of niobic acid (Nb ₂ O ₅ ) used for the preparation was measured by the above method and found to be 0.05%. The average particle diameter of this niobic acid was 15 μm.
First, 600.0 kg of water was put into the mixing tank, and then the water was heated to 50 ° C. Next, with stirring, 382.9 kg of oxalic acid dihydrate [H ₂ C ₂ O ₄ .2H ₂ O] was charged into the mixing tank, and subsequently 79.2% by mass of Nb as Nb ₂ O _5. 102.0 kg of niobic acid having a water content was added and both were mixed in water. The molar ratio of charged oxalic acid / niobium was 5.0, and the charged niobium concentration was 0.56 (mol-Nb / kg-solution).
This solution was heated and stirred in a mixing tank at 95 ° C. for 2 hours to obtain a uniform Nb aqueous mixture. The pressure in the mixing tank at this time was 2.8 kg / cm ² G. The Nb aqueous mixture was allowed to cool to 40 ° C. while being allowed to cool, and then allowed to stand for 12 hours while maintaining the temperature of the Nb aqueous mixture at 35 ° C. The Nb aqueous mixture was then cooled to 8 ° C. at −7.3 ° C./hr and left for 3 hours. The pressure in the mixing tank so far was always maintained at about 2.8 kg / cm ² G by introducing compressed air during cooling.

Thereafter, the Nb aqueous mixture was transferred to the filter connected to the mixing tank by piping, and filtered while stirring to obtain a uniform Nb organic acid aqueous solution. The time required for the filtration was 10 minutes. Stirring in the mixing tank was continued with the same power until immediately before the Nb aqueous mixture containing the solid content of the mixing tank decreased and the liquid level fell below the lower end of the stirring blade. Filtration was performed while applying a pressure of 2.5 kg / cm ² G. At this time, cold water was passed through a jacket provided outside the filter to maintain the temperature of the filter at 8 ° C. When the Nb organic acid aqueous solution after the completion of filtration was sampled and the liquid temperature was measured, the solution temperature was 8 ° C. The oxalic acid / Nb molar ratio of the Nb organic acid aqueous solution at this time was 2 .6. The color of the filtrate at this time was colorless and transparent.

In a crucible, 10 g of an Nb organic acid aqueous solution was precisely weighed, dried overnight at 95 ° C., and then heat treated at 600 ° C. for 1 hour to obtain 1.129 g of solid Nb ₂ O ₅ . From this result, the niobium concentration was 0.69 (mol-Nb / kg-solution).

3 g of Nb organic acid aqueous solution was precisely weighed in a 300 mL glass beaker, 200 mL of hot water at about 80 ° C. was added to the beaker, and subsequently 10 mL of 1: 1 sulfuric acid was added. The mixed solution in the obtained beaker was titrated with 1 / 4N KMnO ₄ under stirring while maintaining the liquid temperature at 70 ° C. on a hot stirrer. The end point was a point where a faint pale pink color by KMnO ₄ lasted for about 30 seconds or more. The concentration of oxalic acid was 1.749 (mol-oxalic acid / kg-solution) as a result of calculation from the titration amount of KMnO ₄ with reference to the following reaction formula.
2KMnO ₄ + 3H ₂ SO ₄ + 5H ₂ C ₂ O ₄ → K ₂ SO ₄ + 2MnSO ₄ + 10CO ₂ + 8H ₂ O
The obtained Nb organic acid aqueous solution was used as an Nb organic acid aqueous solution (A ₀ ) in the production of the following oxide catalyst. Table 1 shows the results of the niobium concentration in the Nb organic acid aqueous solution (during manufacture), the molar ratio of oxalic acid / niobium, and the presence or absence of turbidity of the liquid visually confirmed.

(Preparation of raw material mixture)
25 kg of water, 4.088 kg of ammonium heptamolybdate [(NH ₄ ) ₆ Mo ₇ O ₂₄ · 4H ₂ O], 0.646 kg of ammonium metavanadate [NH ₄ VO ₃ ], antimony trioxide [Sb ₂ O ₃ 0.907 kg and 0.051 kg of cerium nitrate were added, and the mixture was heated at 95 ° C. for 1 hour with stirring to prepare an aqueous mixture (B ₁ ) which was a liquid aqueous mixture.
On the other hand, 0.52 kg of hydrogen peroxide containing 30% by mass of H ₂ O ₂ is added to 3.331 kg of Nb organic acid aqueous solution (A ₀ ), and the mixture is stirred and mixed at room temperature for 10 minutes. / An aqueous complexing agent solution (C ₁ ) was prepared.
After cooling the obtained aqueous mixture (B ₁ ) to 70 ° C., 7.038 kg of silica sol containing 34.0% by mass of SiO ₂ was added to the aqueous mixture (B ₁ ), and further 30% by mass. 1.06 kg of hydrogen peroxide containing ₂ H ₂ O ₂ was added and stirring was continued at 55 ° C. for 30 minutes. Further, in the liquid, the above Nb organic acid compound / complexing agent aqueous solution (C ₁ ) and 2.4 kg of powdered silica (product name “Aerosil 200” manufactured by Nippon Aerosil Co., Ltd.) were dispersed in 197.6 kg of water. Solution and 0.319 kg of ammonium metatungstate solution containing 50.2% by weight as tungsten oxide were sequentially added, followed by stirring at 50 ° C. for 2.5 hours to obtain a slurry-like aqueous mixture (D ₁ )

(Preparation of dry powder (E ₁ ))
Next, the aqueous mixture (D ₁ ) obtained as described above was supplied to a centrifugal spray dryer and dried to obtain a dry powder (E ₁ ) having a fine spherical shape and an average particle diameter of 51 μm. The dryer inlet temperature was 210 ° C. and the outlet temperature was 120 ° C.

(Baking of dry powder (E ₁ ))
500 g of the dry powder (E ₁ ) obtained as described above was filled in an SUS firing tube having an inner diameter of 3 inches (76 mm), a length of 300 mm and a wall thickness of 3 mm, and under a nitrogen gas flow of 5.0 NL / min. The pre-stage firing and the main firing were performed while rotating the firing tube around the length direction. In the pre-stage firing, the temperature was increased from room temperature to 340 ° C. at a temperature raising rate of 0.75 ° C./min, and firing was performed at 340 ° C. for 1 hour. Subsequently, in the main firing, the temperature is increased from 340 ° C. to 670 ° C. at a temperature increase rate of 3 ° C./minute, held at 670 ° C. for 2 hours, and then heated to 350 ° C. at a temperature decrease rate of 1 ° C./minute. A fired body (F ₁ ) was obtained.

(Removal of protrusions)
The protrusions present on the surface of the catalyst particles were removed by the following method. 50 g of the fired body (F ₁ ) was charged into a vertical tube (inner diameter: 41.6 mm, length: 70 cm) provided with a holed disk having three holes with a diameter of 1/64 inch at the bottom and provided with a paper filter at the top. The airflow length in the direction in which the airflow flows at this time was 52 mm, and the average linear velocity of the airflow was 310 m / s. No protrusions were present in the composite oxide catalyst (G ₁ ) obtained after 24 hours.

(Propane ammoxidation reaction)
Propane was subjected to a gas phase ammoxidation reaction by the following method using the oxide catalyst obtained as described above. A Vycor glass fluidized bed reaction tube having an inner diameter of 25 mm is filled with 35 g of an oxide catalyst, the reaction temperature is set to 440 ° C., the reaction pressure is set to normal pressure, and propane: ammonia: oxygen: helium = 1: 1: 3: 18. A gas mixture having a molar ratio of 2.8 was supplied at a contact time of 2.8 (sec · g / cc). Table 1 shows the propane conversion and acrylonitrile (AN) yield after the reaction.

(Example 2)
Composition formula was prepared by an oxide catalyst represented by _{Mo 1 V 0.24 W 0.04 Nb 0.11} Sb 0.26 Ce 0.005 O n /48.0 wt% -SiO ₂ as follows.
(Preparation of Nb organic acid aqueous solution)
An Nb organic acid aqueous solution was prepared in the same manner as in Example 1 except that niobic acid having an Nb residue ratio and an average particle size shown in Table 1 was used. Table 1 shows the filtration time of the Nb organic acid aqueous solution and the niobium concentration in the obtained Nb organic acid aqueous solution.
(Preparation of raw material mixture)
A raw material preparation solution was prepared in the same manner as in Example 1 except that 3.380 kg of the Nb organic acid aqueous solution was used.
(Preparation and firing of dry powder (E ₁ ))
A dry powder (E ₁ ) was prepared in the same manner as in Example 1 except that the raw material preparation solution was used, and the dry powder (E ₁ ) was fired in the same manner as in Example 1 to obtain a fired body ( F ₁₎ was obtained.
(Removal of protrusions)
A protrusion was removed to prepare a composite oxide catalyst (G ₁ ) in the same manner as in Example 1 except that the fired body was used.
(Propane ammoxidation reaction)
Propane ammoxidation was carried out in the same manner as in Example 1 except that the composite oxide catalyst (G ₁ ) was used. The results are shown in Table 1.

Example 3
Composition formula was prepared by an oxide catalyst represented by _{Mo 1 V 0.24 W 0.04 Nb 0.11} Sb 0.26 Ce 0.005 O n /48.0 wt% -SiO ₂ as follows.
(Preparation of Nb organic acid aqueous solution)
An Nb organic acid aqueous solution was prepared in the same manner as in Example 1 except that niobic acid having an Nb residue ratio and an average particle size shown in Table 1 was used. Table 1 shows the filtration time of the Nb organic acid aqueous solution and the niobium concentration in the obtained Nb organic acid aqueous solution.
(Preparation of raw material mixture)
A raw material preparation solution was prepared in the same manner as in Example 1 except that 3.431 kg of the Nb organic acid aqueous solution was used.
(Preparation and firing of dry powder (E ₁ ))
A dry powder (E ₁ ) was prepared in the same manner as in Example 1 except that the raw material preparation solution was used, and the dry powder (E ₁ ) was fired in the same manner as in Example 1 to obtain a fired body ( F ₁₎ was obtained.
(Removal of protrusions)
A protrusion was removed to prepare a composite oxide catalyst (G ₁ ) in the same manner as in Example 1 except that the fired body was used.
(Propane ammoxidation reaction)
Propane ammoxidation was carried out in the same manner as in Example 1 except that the composite oxide catalyst (G ₁ ) was used. The results are shown in Table 1.

(Comparative Example 1)
Composition formula was prepared by an oxide catalyst represented by _{Mo 1 V 0.24 W 0.04 Nb 0.11} Sb 0.26 Ce 0.005 O n /48.0 wt% -SiO ₂ as follows.
(Preparation of Nb organic acid aqueous solution)
An Nb organic acid aqueous solution was prepared in the same manner as in Example 1 except that niobic acid having an Nb residue ratio and an average particle size shown in Table 1 was used. Table 1 shows the filtration time of the Nb organic acid aqueous solution and the niobium concentration in the obtained Nb organic acid aqueous solution.
(Preparation of raw material mixture)
A raw material preparation solution was prepared in the same manner as in Example 1 except that 7.662 kg of the Nb organic acid aqueous solution was used.
(Preparation and firing of dry powder (E ₁ ))
A dry powder (E ₁ ) was prepared in the same manner as in Example 1 except that the raw material preparation solution was used, and the dry powder (E ₁ ) was fired in the same manner as in Example 1 to obtain a fired body ( F ₁₎ was obtained.
(Removal of protrusions)
A protrusion was removed to prepare a composite oxide catalyst (G ₁ ) in the same manner as in Example 1 except that the fired body was used.
(Propane ammoxidation reaction)
Propane ammoxidation was carried out in the same manner as in Example 1 except that the composite oxide catalyst (G ₁ ) was used. The results are shown in Table 1.

(Comparative Example 2)
Composition formula was prepared by an oxide catalyst represented by _{Mo 1 V 0.24 W 0.04 Nb 0.11} Sb 0.26 Ce 0.005 O n /48.0 wt% -SiO ₂ as follows.
(Preparation of Nb organic acid aqueous solution)
An Nb organic acid aqueous solution was prepared in the same manner as in Example 1 except that niobic acid having an Nb residue ratio and an average particle size shown in Table 1 was used. Table 1 shows the filtration time of the Nb organic acid aqueous solution and the niobium concentration in the obtained Nb organic acid aqueous solution.
(Preparation of raw material mixture)
A raw material preparation solution was prepared in the same manner as in Example 1 except that 6.050 kg of the Nb organic acid aqueous solution was used.
(Preparation and firing of dry powder (E ₁ ))
A dry powder (E ₁ ) was prepared in the same manner as in Example 1 except that the raw material preparation solution was used, and the dry powder (E ₁ ) was fired in the same manner as in Example 1 to obtain a fired body ( F ₁₎ was obtained.
(Removal of protrusions)
A protrusion was removed to prepare a composite oxide catalyst (G ₁ ) in the same manner as in Example 1 except that the fired body was used.
(Propane ammoxidation reaction)
Propane ammoxidation was carried out in the same manner as in Example 1 except that the composite oxide catalyst (G ₁ ) was used. The results are shown in Table 1.

(Comparative Example 3)
Composition formula was prepared by an oxide catalyst represented by _{Mo 1 V 0.24 W 0.04 Nb 0.11} Sb 0.26 Ce 0.005 O n /48.0 wt% -SiO ₂ as follows.
(Preparation of Nb organic acid aqueous solution)
An Nb organic acid aqueous solution was prepared in the same manner as in Example 1 except that niobic acid having an Nb residue ratio and an average particle size shown in Table 1 was used. Table 1 shows the filtration time of the Nb organic acid aqueous solution and the niobium concentration in the obtained Nb organic acid aqueous solution.
(Preparation of raw material mixture)
A raw material preparation solution was prepared in the same manner as in Example 1 except that 5.474 kg of the Nb organic acid aqueous solution was used.
(Preparation and firing of dry powder (E ₁ ))
A dry powder (E ₁ ) was prepared in the same manner as in Example 1 except that the raw material preparation solution was used, and the dry powder (E ₁ ) was fired in the same manner as in Example 1 to obtain a fired body ( F ₁₎ was obtained.
(Removal of protrusions)
A protrusion was removed to prepare a composite oxide catalyst (G ₁ ) in the same manner as in Example 1 except that the fired body was used.
(Propane ammoxidation reaction)
Propane ammoxidation was carried out in the same manner as in Example 1 except that the composite oxide catalyst (G ₁ ) was used. The results are shown in Table 1.

Example 4
Composition formula was prepared by an oxide catalyst represented by _{Mo 1 V 0.24 W 0.04 Nb 0.11} Sb 0.26 Ce 0.005 O n /48.0 wt% -SiO ₂ as follows.
(Preparation of Nb aqueous mixture)
First, 1330.0 kg of water was put into the mixing tank, and then the water was heated to 50 ° C. Next, with stirring, 732.1 kg of oxalic acid dihydrate [H ₂ C ₂ O ₄ .2H ₂ O] was charged into the mixing tank, and subsequently 81.0 mass% Nb as Nb ₂ O _5. 195.0 kg of niobic acid having a water content was added and both were mixed in water. The molar ratio of charged oxalic acid / niobium was 5.0, and the charged niobium concentration was 0.515 (mol-Nb / kg-solution).
This solution was heated and stirred at 95 ° C. for 2 hours in a mixing tank to obtain an Nb aqueous mixture in which the solid content was uniformly dispersed. The pressure in the mixing tank at this time was 1.2 kg / cm ² G. The Nb aqueous mixture was allowed to cool to 40 ° C. while being allowed to cool, and then allowed to stand for 12 hours while maintaining the temperature of the Nb aqueous mixture at 35 ° C. The Nb aqueous mixture was then cooled to 13 ° C. at −7.3 ° C./hr and left for 3 hours. The pressure in the mixing tank so far was always kept at about 1.2 kg / cm ² G by introducing compressed air during cooling.

Thereafter, the Nb aqueous mixture was transferred via a pipe to a filter connected to the mixing tank by a pipe, and filtered with stirring to obtain an Nb organic acid aqueous solution in which the solid content was uniformly dispersed. The time required for the filtration was 70 minutes. Stirring in the mixing tank was continued with the same power until immediately before the Nb aqueous mixture containing the solid content of the mixing tank decreased and the liquid level fell below the lower end of the stirring blade. Filtration was performed while applying a pressure of 0.5 kg / cm ² G. The molar ratio of oxalic acid / Nb in the Nb organic acid aqueous solution was 2.70 from the following analysis.

In a crucible, 10 g of an Nb organic acid aqueous solution was precisely weighed, dried overnight at 95 ° C., and then heat-treated at 600 ° C. for 1 hour to obtain 0.978 g of solid Nb ₂ O ₅ . From this result, the niobium concentration was 0.583 (mol-Nb / kg-solution).

3 g of Nb organic acid aqueous solution was precisely weighed in a 300 mL glass beaker, 200 mL of hot water at about 80 ° C. was added to the beaker, and subsequently 10 mL of 1: 1 sulfuric acid was added. The mixed solution in the obtained beaker was titrated with 1 / 4N KMnO ₄ under stirring while maintaining the liquid temperature at 70 ° C. on a hot stirrer. The end point was a point where a faint pale pink color by KMnO ₄ lasted for about 30 seconds or more. The concentration of oxalic acid was 1.574 (mol-oxalic acid / kg-solution).

(Preparation of raw material mixture)
A raw material preparation liquid was prepared in the same manner as in Example 1 except that the Nb organic acid aqueous solution was used.
(Preparation and firing of dry powder (E ₁ ))
A dry powder (E ₁ ) was prepared in the same manner as in Example 1 except that the raw material preparation solution was used, and the dry powder (E ₁ ) was fired in the same manner as in Example 1 to obtain a fired body ( F ₁₎ was obtained.
(Removal of protrusions)
A protrusion was removed to prepare a composite oxide catalyst (G ₁ ) in the same manner as in Example 1 except that the fired body was used.
(Propane ammoxidation reaction)
Propane ammoxidation was carried out in the same manner as in Example 1 except that the composite oxide catalyst (G ₁ ) was used. The results are shown in Table 1.

(Example 5)
Composition formula was prepared by an oxide catalyst represented by _{Mo 1 V 0.24 W 0.04 Nb 0.11} Sb 0.26 Ce 0.005 O n /48.0 wt% -SiO ₂ as follows.
(Preparation of Nb aqueous mixture)
First, 1.00 kg of water was put into the mixing tank, and then the water was heated to 50 ° C. Next, with stirring, 0.63 kg of oxalic acid dihydrate [H ₂ C ₂ O ₄ .2H ₂ O] was charged into the mixing tank, and subsequently 79.2% by mass of Nb ₂ O ₅ as Nb ₂ O _5. 0.17 kg of niobic acid having a water content was added and both were mixed in water. The molar ratio of charged oxalic acid / niobium was 5.0, and the charged niobium concentration was 0.56 (mol-Nb / kg-solution).
This solution was heated and stirred in a mixing tank at 95 ° C. for 2 hours to obtain a uniform Nb aqueous mixture. The pressure in the mixing tank at this time was 1.2 kg / cm ² G. The Nb aqueous mixture was allowed to cool to 40 ° C. while being allowed to cool, and then allowed to stand for 12 hours while maintaining the temperature of the Nb aqueous mixture at 35 ° C. The Nb aqueous mixture was then cooled to 12 ° C. at −7.3 ° C./hr and left for 3 hours. The pressure in the mixing tank so far was always maintained at 1.2 kg / cm ² G by introducing compressed air during cooling.

Thereafter, the Nb aqueous mixture was transferred to a filter and separated by pressure filtration (pressure = 0.7 kg / cm ² G) to obtain an Nb organic acid aqueous solution in which the solid content was uniformly dispersed. The time required for filtration was 0.5 minutes. Stirring in the mixing tank was continued with the same power until immediately before the Nb aqueous mixture containing the solid content of the mixing tank decreased and the liquid level fell below the lower end of the stirring blade. At this time, cold water was passed through a jacket provided outside the filter to maintain the temperature of the filter at 12 ° C. When the filtrate (Nb organic acid aqueous solution) was sampled and the liquid temperature was measured, the temperature of the filtrate was 12 ° C. Further, the niobium concentration in the filtrate was 0.65 (mol-Nb / kg-liquid) and the concentration of oxalic acid was 1.63 (mol-oxalic acid / kg), so oxalic acid / Nb The molar ratio of was 2.50.

(Preparation of raw material mixture)
A raw material preparation solution was prepared in the same manner as in Example 1 except that 3.521 kg of the Nb organic acid aqueous solution was used.
(Preparation and firing of dry powder (E ₁ ))
A dry powder (E ₁ ) was prepared in the same manner as in Example 1 except that the raw material preparation solution was used, and the dry powder (E ₁ ) was fired in the same manner as in Example 1 to obtain a fired body ( F ₁₎ was obtained.
(Removal of protrusions)
A protrusion was removed to prepare a composite oxide catalyst (G ₁ ) in the same manner as in Example 1 except that the fired body was used.
(Propane ammoxidation reaction)
Propane ammoxidation was carried out in the same manner as in Example 1 except that the composite oxide catalyst (G ₁ ) was used. The results are shown in Table 1.

(Example 6)
Composition formula was prepared by an oxide catalyst represented by _{Mo 1 V 0.24 W 0.04 Nb 0.11} Sb 0.26 Ce 0.005 O n /48.0 wt% -SiO ₂ as follows.
(Preparation of Nb organic acid aqueous solution)
An Nb organic acid aqueous solution was prepared in the same manner as in Example 1 except that niobic acid having an Nb residue ratio and an average particle size shown in Table 1 was used. Table 1 shows the filtration time of the Nb organic acid aqueous solution and the niobium concentration in the obtained Nb organic acid aqueous solution.
(Preparation of raw material mixture)
A raw material preparation liquid was prepared in the same manner as in Example 1 except that the Nb organic acid aqueous solution was used.
(Preparation and firing of dry powder (E ₁ ))
A dry powder (E ₁ ) was prepared in the same manner as in Example 1 except that the raw material preparation solution was used, and the dry powder (E ₁ ) was fired in the same manner as in Example 1 to obtain a fired body ( F ₁₎ was obtained.
(Removal of protrusions)
A protrusion was removed to prepare a composite oxide catalyst (G ₁ ) in the same manner as in Example 1 except that the fired body was used.
(Propane ammoxidation reaction)
Propane ammoxidation was carried out in the same manner as in Example 1 except that the composite oxide catalyst (G ₁ ) was used. The results are shown in Table 1.

(Example 7)
Composition formula was prepared by an oxide catalyst represented by _{Mo 1 V 0.24 W 0.04 Nb 0.11} Sb 0.26 Ce 0.005 O n /48.0 wt% -SiO ₂ as follows.
(Preparation of Nb organic acid aqueous solution)
An Nb organic acid aqueous solution was prepared in the same manner as in Example 1 except that niobic acid having an Nb residue ratio and an average particle size shown in Table 1 was used. Table 1 shows the filtration time of the Nb organic acid aqueous solution and the niobium concentration in the obtained Nb organic acid aqueous solution.
(Preparation of raw material mixture)
A raw material preparation liquid was prepared in the same manner as in Example 1 except that the Nb organic acid aqueous solution was used.
(Preparation and firing of dry powder (E ₁ ))
A dry powder (E ₁ ) was prepared in the same manner as in Example 1 except that the raw material preparation solution was used, and the dry powder (E ₁ ) was fired in the same manner as in Example 1 to obtain a fired body ( F ₁₎ was obtained.
(Removal of protrusions)
A protrusion was removed to prepare a composite oxide catalyst (G ₁ ) in the same manner as in Example 1 except that the fired body was used.
(Propane ammoxidation reaction)
Propane ammoxidation was carried out in the same manner as in Example 1 except that the composite oxide catalyst (G ₁ ) was used. The results are shown in Table 1.

(Example 8)
Composition formula was prepared by an oxide catalyst represented by _{Mo 1 V 0.24 W 0.04 Nb 0.11} Sb 0.26 Ce 0.005 O n /48.0 wt% -SiO ₂ as follows.
(Preparation of Nb organic acid aqueous solution)
An Nb organic acid aqueous solution was prepared in the same manner as in Example 1 except that niobic acid having an Nb residue ratio and an average particle diameter shown in Table 1 was used and 456.2 kg of tartaric acid was used as the organic acid. Table 1 shows the filtration time of the Nb organic acid aqueous solution and the niobium concentration in the obtained Nb organic acid aqueous solution.
(Preparation of raw material mixture)
A raw material preparation liquid was prepared in the same manner as in Example 1 except that the Nb organic acid aqueous solution was used.
(Preparation and firing of dry powder (E ₁ ))
A dry powder (E ₁ ) was prepared in the same manner as in Example 1 except that the raw material preparation solution was used, and the dry powder (E ₁ ) was fired in the same manner as in Example 1 to obtain a fired body ( F ₁₎ was obtained.
(Removal of protrusions)
A protrusion was removed to prepare a composite oxide catalyst (G ₁ ) in the same manner as in Example 1 except that the fired body was used.
(Propane ammoxidation reaction)
Propane ammoxidation was carried out in the same manner as in Example 1 except that the composite oxide catalyst (G ₁ ) was used. The results are shown in Table 1.

Example 9
Composition formula was prepared by an oxide catalyst represented by _{Mo 1 V 0.24 W 0.04 Nb 0.11} Sb 0.26 Ce 0.005 O n /48.0 wt% -SiO ₂ as follows.
(Preparation of Nb organic acid aqueous solution)
An Nb organic acid aqueous solution was prepared in the same manner as in Example 1 except that 109.0 kg of niobium ammonium oxalate whose Nb residue rate and average particle size are those shown in Table 1 was used. Table 1 shows the filtration time of the Nb organic acid aqueous solution and the niobium concentration in the obtained Nb organic acid aqueous solution.
(Preparation of raw material mixture)
A raw material preparation liquid was prepared in the same manner as in Example 1 except that the Nb organic acid aqueous solution was used.
(Preparation and firing of dry powder (E ₁ ))
A dry powder (E ₁ ) was prepared in the same manner as in Example 1 except that the raw material preparation solution was used, and the dry powder (E ₁ ) was fired in the same manner as in Example 1 to obtain a fired body ( F ₁₎ was obtained.
(Removal of protrusions)
A protrusion was removed to prepare a composite oxide catalyst (G ₁ ) in the same manner as in Example 1 except that the fired body was used.
(Propane ammoxidation reaction)
Propane ammoxidation was carried out in the same manner as in Example 1 except that the composite oxide catalyst (G ₁ ) was used. The results are shown in Table 1.

(Example 10)
Composition formula was prepared by an oxide catalyst represented by _{Mo 1 V 0.24 W 0.04 Nb 0.11} Sb 0.26 Ce 0.005 O n /48.0 wt% -SiO ₂ as follows.
(Preparation of Nb organic acid aqueous solution)
Instead of hydrogen peroxide, the same procedure as in Example 1 was performed except that 52.5 kg of citric acid monohydrate [H ₈ C ₆ O ₇ · H ₂ O] equimolar to hydrogen peroxide was added as a complexing agent. A Nb organic acid aqueous solution was prepared. Table 1 shows the filtration time of the Nb organic acid aqueous solution and the niobium concentration in the obtained Nb organic acid aqueous solution.
(Preparation of raw material mixture)
A raw material preparation liquid was prepared in the same manner as in Example 1 except that the Nb organic acid aqueous solution was used.
(Preparation and firing of dry powder (E ₁ ))
A dry powder (E ₁ ) was prepared in the same manner as in Example 1 except that the raw material preparation solution was used, and the dry powder (E ₁ ) was fired in the same manner as in Example 1 to obtain a fired body ( F ₁₎ was obtained.
(Removal of protrusions)
A protrusion was removed to prepare a composite oxide catalyst (G ₁ ) in the same manner as in Example 1 except that the fired body was used.
(Propane ammoxidation reaction)
Propane ammoxidation was carried out in the same manner as in Example 1 except that the composite oxide catalyst (G ₁ ) was used. The results are shown in Table 1.

(Example 11)
Composition formula was prepared by an oxide catalyst represented by _{Mo 1 V 0.24 W 0.04 Nb 0.11} Sb 0.26 Ce 0.005 O n /48.0 wt% -SiO ₂ as follows.
(Preparation of Nb organic acid aqueous solution)
An Nb organic acid aqueous solution was prepared in the same manner as in Example 1 except that niobic acid having an Nb residue ratio and an average particle size shown in Table 1 was used. Table 1 shows the filtration time of the Nb organic acid aqueous solution and the niobium concentration in the obtained Nb organic acid aqueous solution.
(Preparation of raw material mixture)
A raw material preparation solution was prepared in the same manner as in Example 1 except that 4.033 kg of the Nb organic acid aqueous solution was used.
(Preparation and firing of dry powder (E ₁ ))
A dry powder (E ₁ ) was prepared in the same manner as in Example 1 except that the raw material preparation solution was used, and the dry powder (E ₁ ) was fired in the same manner as in Example 1 to obtain a fired body ( F ₁₎ was obtained.
(Removal of protrusions)
A protrusion was removed to prepare a composite oxide catalyst (G ₁ ) in the same manner as in Example 1 except that the fired body was used.
(Propane ammoxidation reaction)
Propane ammoxidation was carried out in the same manner as in Example 1 except that the composite oxide catalyst (G ₁ ) was used. The results are shown in Table 1.

Example 12
Composition formula was prepared by an oxide catalyst represented by _{Mo 1 V 0.24 W 0.04 Nb 0.11} Sb 0.26 Ce 0.005 O n /48.0 wt% -SiO ₂ as follows.
(Preparation of Nb organic acid aqueous solution)
An Nb organic acid aqueous solution was prepared in the same manner as in Example 1 except that niobic acid having an Nb residue ratio and an average particle size shown in Table 1 was used. Table 1 shows the filtration time of the Nb organic acid aqueous solution and the niobium concentration in the obtained Nb organic acid aqueous solution.
(Preparation of raw material mixture)
A raw material preparation solution was prepared in the same manner as in Example 1 except that 4.421 kg of the Nb organic acid aqueous solution was used.
(Preparation and firing of dry powder (E ₁ ))
A dry powder (E ₁ ) was prepared in the same manner as in Example 1 except that the raw material preparation solution was used, and the dry powder (E ₁ ) was fired in the same manner as in Example 1 to obtain a fired body ( F ₁₎ was obtained.
(Removal of protrusions)
A protrusion was removed to prepare a composite oxide catalyst (G ₁ ) in the same manner as in Example 1 except that the fired body was used.
(Propane ammoxidation reaction)
Propane ammoxidation was carried out in the same manner as in Example 1 except that the composite oxide catalyst (G ₁ ) was used. The results are shown in Table 1.

(Example 13)
Composition formula was prepared by an oxide catalyst represented by _{Mo 1 V 0.24 W 0.04 Nb 0.11} Sb 0.26 Ce 0.005 O n /48.0 wt% -SiO ₂ as follows.
(Preparation of Nb organic acid aqueous solution)
An Nb organic acid aqueous solution was prepared in the same manner as in Example 1 except that niobic acid having an Nb residue ratio and an average particle size shown in Table 1 was used. Table 1 shows the filtration time of the Nb organic acid aqueous solution and the niobium concentration in the obtained Nb organic acid aqueous solution.
(Preparation of raw material mixture)
A raw material preparation solution was prepared in the same manner as in Example 1 except that 3.768 kg of the Nb organic acid aqueous solution was used.
(Preparation and firing of dry powder (E ₁ ))
A dry powder (E ₁ ) was prepared in the same manner as in Example 1 except that the raw material preparation solution was used, and the dry powder (E ₁ ) was fired in the same manner as in Example 1 to obtain a fired body ( F ₁₎ was obtained.
(Removal of protrusions)
A protrusion was removed to prepare a composite oxide catalyst (G ₁ ) in the same manner as in Example 1 except that the fired body was used.
(Propane ammoxidation reaction)
Propane ammoxidation was carried out in the same manner as in Example 1 except that the composite oxide catalyst (G ₁ ) was used. The results are shown in Table 1.

(Example 14)
Composition formula was prepared by an oxide catalyst represented by _{Mo 1 V 0.24 W 0.04 Nb 0.11} Sb 0.26 Ce 0.005 O n /48.0 wt% -SiO ₂ as follows.
(Preparation of Nb organic acid aqueous solution)
An Nb organic acid aqueous solution was prepared in the same manner as in Example 1 except that niobic acid having an Nb residue ratio and an average particle size shown in Table 1 was used. Table 1 shows the filtration time of the Nb organic acid aqueous solution and the niobium concentration in the obtained Nb organic acid aqueous solution.
(Preparation of raw material mixture)
A raw material preparation solution was prepared in the same manner as in Example 1 except that 4.180 kg of the Nb organic acid aqueous solution was used.
(Preparation and firing of dry powder (E ₁ ))
A dry powder (E ₁ ) was prepared in the same manner as in Example 1 except that the raw material preparation solution was used, and the dry powder (E ₁ ) was fired in the same manner as in Example 1 to obtain a fired body ( F ₁₎ was obtained.
(Removal of protrusions)
A protrusion was removed to prepare a composite oxide catalyst (G ₁ ) in the same manner as in Example 1 except that the fired body was used.
(Propane ammoxidation reaction)
Propane ammoxidation was carried out in the same manner as in Example 1 except that the composite oxide catalyst (G ₁ ) was used. The results are shown in Table 1.

(Example 15)
An oxide catalyst having a composition formula of Mo ₁ V _0.24 Nb _0.11 Sb _0.26 O _n / 48 mass% -SiO ₂ was prepared as follows.
(Preparation of raw material mixture)
19.8 kg of water in the container, 4.317 kg of ammonium heptamolybdate [(NH ₄ ) ₆ Mo ₇ O ₂₄ · 4H ₂ O], 0.682 kg of ammonium metavanadate [NH ₄ VO ₃ ], 0.922 kg of antimony [Sb ₂ O ₃ ] was added and heated at 95 ° C. for 1 hour with stirring to obtain a liquid aqueous mixture (B ₁ ).
0.63 kg of hydrogen peroxide containing 30% by mass of H ₂ O ₂ was added to 3.986 kg of the Nb organic acid aqueous solution prepared in the same manner as in Example 1. While maintaining the liquid temperature at about 20 ° C., the mixture was stirred and mixed to obtain an Nb organic acid compound / complex forming agent aqueous solution.
After the aqueous mixture (B ₁ ) was cooled to 70 ° C., 6.891 kg of silica sol containing 34.1% by mass of SiO ₂ was added. Next, 1.07 kg of hydrogen peroxide containing 30% by mass of H ₂ O ₂ was added, and after stirring and mixing at 50 ° C. for 1 hour, an Nb organic acid compound / complexing agent aqueous solution was added. Furthermore, a liquid in which 2.35 kg of fumed silica was dispersed in 32.9 kg of water was added and stirred at 50 ° C. for 2.5 hours to obtain a raw material preparation liquid.
(Preparation and firing of dry powder (E ₁ ))
A dry powder (E ₁ ) was prepared in the same manner as in Example 1 except that the raw material preparation solution was used, and the dry powder (E ₁ ) was fired in the same manner as in Example 1 to obtain a fired body ( F ₁₎ was obtained.
(Removal of protrusions)
A protrusion was removed to prepare a composite oxide catalyst (G ₁ ) in the same manner as in Example 1 except that the fired body was used.
(Propane ammoxidation reaction)
Propane ammoxidation was carried out in the same manner as in Example 1 except that the composite oxide catalyst (G ₁ ) was used. The results are shown in Table 2.

(Example 16)
An oxide catalyst having a composition formula of Mo ₁ V _0.24 Nb _0.11 Sb _0.26 W _0.03 Mn _0.002 / 48 mass% -SiO ₂ was prepared as follows.
(Preparation of raw material mixture)
Into 19.8 kg of water in the container, 4.181 kg of ammonium heptamolybdate [(NH ₄ ) ₆ Mo ₇ O ₂₄ · 4H ₂ O], 0.661 kg of ammonium metavanadate [NH ₄ VO ₃ ], antimony trioxide 0.896 kg of [Sb ₂ O ₃ ] was added and heated at 95 ° C. for 1 hour with stirring to obtain a liquid aqueous mixture (B ₁ ).
0.59 kg of hydrogen peroxide containing 30% by mass of H ₂ O ₂ was added to 3.861 kg of the Nb organic acid aqueous solution prepared in the same manner as in Example 1. While maintaining the liquid temperature at about 20 ° C., the mixture was stirred and mixed to obtain an Nb organic acid compound / complex forming agent aqueous solution.
After cooling the aqueous mixture (B ₁ ) to 70 ° C., 7.73 kg of silica sol containing 30.4% by mass of SiO ₂ was added. Next, 1.04 kg of hydrogen peroxide containing 30% by mass of H ₂ O ₂ was added and stirred and mixed at 50 ° C. for 1 hour, and then an Nb organic acid compound / complex forming agent aqueous solution was added. Furthermore, a liquid obtained by dispersing 2.35 kg of fumed silica in 32.9 kg of water, 0.327 kg of ammonium metatungstate containing 50% by mass of WO ₃ , and manganese nitrate [Mn (NO ₃ ) ₂ .6H ₂ O] 0.014 kg was sequentially added and stirred at 50 ° C. for 2.5 hours to obtain a raw material preparation solution.
(Preparation and firing of dry powder (E ₁ ))
A dry powder (E ₁ ) was prepared in the same manner as in Example 1 except that the raw material preparation solution was used, and the dry powder (E ₁ ) was fired in the same manner as in Example 1 to obtain a fired body ( F ₁₎ was obtained.
(Removal of protrusions)
A protrusion was removed to prepare a composite oxide catalyst (G ₁ ) in the same manner as in Example 1 except that the fired body was used.
(Propane ammoxidation reaction)
Propane ammoxidation was carried out in the same manner as in Example 1 except that the composite oxide catalyst (G ₁ ) was used. The results are shown in Table 2.

(Example 17)
An oxide catalyst having a composition formula of Mo ₁ V _0.24 Nb _0.11 Sb _0.26 B _0.05 / 48 mass% -SiO ₂ was prepared as follows.
(Preparation of raw material mixture)
Into 19.8 kg of water in the container, 4.283 kg of ammonium heptamolybdate [(NH ₄ ) ₆ Mo ₇ O ₂₄ · 4H ₂ O], 0.677 kg of ammonium metavanadate [NH ₄ VO ₃ ], antimony trioxide 0.917 kg of [Sb ₂ O ₃ ] was added and heated at 95 ° C. for 1 hour with stirring to obtain a liquid aqueous mixture (B ₁ ).
To 3.955 kg of an Nb organic acid aqueous solution prepared in the same manner as in Example 1, 0.60 kg of hydrogen peroxide containing 30% by mass of H ₂ O ₂ was added. While maintaining the liquid temperature at about 20 ° C., the mixture was stirred and mixed to obtain an Nb organic acid compound / complex forming agent aqueous solution.
After cooling the aqueous mixture (B ₁ ) to 70 ° C., 7.73 kg of silica sol containing 30.4% by mass of SiO ₂ was added. Next, 1.07 kg of hydrogen peroxide containing 30% by mass of H ₂ O ₂ was added, and after stirring and mixing at 50 ° C. for 1 hour, an Nb organic acid compound / complexing agent aqueous solution was added. Further, a solution obtained by dispersing 2.35 kg of fumed silica in 32.9 kg of water and 0.075 kg of boric acid [H ₃ BO ₃ ] were added in order, and the mixture was stirred at 50 ° C. for 2.5 hours. A preparation was obtained.
(Preparation and firing of dry powder (E ₁ ))
A dry powder (E ₁ ) was prepared in the same manner as in Example 1 except that the raw material preparation solution was used, and the dry powder (E ₁ ) was fired in the same manner as in Example 1 to obtain a fired body ( F ₁₎ was obtained.
(Removal of protrusions)
A protrusion was removed to prepare a composite oxide catalyst (G ₁ ) in the same manner as in Example 1 except that the fired body was used.
(Propane ammoxidation reaction)
Propane ammoxidation was carried out in the same manner as in Example 1 except that the composite oxide catalyst (G ₁ ) was used. The results are shown in Table 2.

(Example 18)
An oxide catalyst having a composition formula of Mo ₁ V _0.24 Nb _0.11 Sb _0.26 Al _0.01 / 48 mass% -SiO ₂ was prepared as follows.
(Preparation of raw material mixture)
19.8 kg of water in the container was 4.307 kg of ammonium heptamolybdate [(NH ₄ ) ₆ Mo ₇ O ₂₄ · 4H ₂ O], 0.680 kg of ammonium metavanadate [NH ₄ VO ₃ ], antimony trioxide 0.922 kg of [Sb ₂ O ₃ ] was added and heated at 95 ° C. for 1 hour with stirring to obtain a liquid aqueous mixture (B ₁ ).
To 3.977 kg of the Nb organic acid aqueous solution prepared in the same manner as in Example 1, 0.60 kg of hydrogen peroxide containing 30% by mass of H ₂ O ₂ was added. While maintaining the liquid temperature at about 20 ° C., the mixture was stirred and mixed to obtain an Nb organic acid compound / complex forming agent aqueous solution.
After the aqueous mixture (B ₁ ) was cooled to 70 ° C., 7.781 kg of silica sol containing 30.2% by mass of SiO ₂ was added. Next, 1.07 kg of hydrogen peroxide containing 30% by mass of H ₂ O ₂ was added, and after stirring and mixing at 50 ° C. for 1 hour, an Nb organic acid compound / complexing agent aqueous solution was added. Further, a solution obtained by dispersing 2.35 kg of fumed silica in 32.9 kg of water and 0.012 kg of aluminum oxide [Al ₂ O ₃ ] were sequentially added, and the mixture was stirred at 50 ° C. for 2.5 hours. A preparation was obtained.
(Preparation and firing of dry powder (E ₁ ))
A dry powder (E ₁ ) was prepared in the same manner as in Example 1 except that the raw material preparation solution was used, and the dry powder (E ₁ ) was fired in the same manner as in Example 1 to obtain a fired body ( F ₁₎ was obtained.
(Removal of protrusions)
A protrusion was removed to prepare a composite oxide catalyst (G ₁ ) in the same manner as in Example 1 except that the fired body was used.
(Propane ammoxidation reaction)
Propane ammoxidation was carried out in the same manner as in Example 1 except that the composite oxide catalyst (G ₁ ) was used. The results are shown in Table 2.

(Example 19)
An oxide catalyst having a composition formula of Mo ₁ V _0.24 Nb _0.11 Sb _0.26 Ti _0.008 / 48 mass% -SiO ₂ was prepared as follows.
(Preparation of raw material mixture)
19.8 kg of water in the container is 4.305 kg of ammonium heptamolybdate [(NH ₄ ) ₆ Mo ₇ O ₂₄ · 4H ₂ O], 0.68 kg of ammonium metavanadate [NH ₄ VO ₃ ], antimony trioxide 0.922 kg of [Sb ₂ O ₃ ] was added and heated at 95 ° C. for 1 hour with stirring to obtain a liquid aqueous mixture (B ₁ ).
To 3.975 kg of an Nb organic acid aqueous solution prepared in the same manner as in Example 1, 0.60 kg of hydrogen peroxide containing 30% by mass of H ₂ O ₂ was added. While maintaining the liquid temperature at about 20 ° C., the mixture was stirred and mixed to obtain an Nb organic acid compound / complex forming agent aqueous solution.
After cooling the aqueous mixture (B ₁ ) to 70 ° C., 7.73 kg of silica sol containing 30.4% by mass of SiO ₂ was added. Subsequently, 1.07 g of hydrogen peroxide containing 30% by mass of H ₂ O ₂ was added and stirred and mixed at 50 ° C. for 1 hour, and then an Nb organic acid compound / complex forming agent aqueous solution was added. Further, a solution in which 2.35 kg of fumed silica was dispersed in 32.9 kg of water and 0.015 kg of titanium oxide [TiO ₂ ] were sequentially added, and the mixture was stirred at 50 ° C. for 2.5 hours to prepare a raw material preparation solution Got.
(Preparation and firing of dry powder (E ₁ ))
A dry powder (E ₁ ) was prepared in the same manner as in Example 1 except that the raw material preparation solution was used, and the dry powder (E ₁ ) was fired in the same manner as in Example 1 to obtain a fired body ( F ₁₎ was obtained.
(Removal of protrusions)
A protrusion was removed to prepare a composite oxide catalyst (G ₁ ) in the same manner as in Example 1 except that the fired body was used.
(Propane ammoxidation reaction)
Propane ammoxidation was carried out in the same manner as in Example 1 except that the composite oxide catalyst (G ₁ ) was used. The results are shown in Table 2.

(Example 20)
An oxide catalyst having a composition formula of Mo ₁ V _0.24 Nb _0.11 Sb _0.26 Ta _0.01 / 48 mass% -SiO ₂ was prepared as follows.
(Preparation of raw material mixture)
Into 19.8 kg of water in the container was 4.143 kg of ammonium heptamolybdate [(NH ₄ ) ₆ Mo ₇ O ₂₄ · 4H ₂ O], 0.655 kg of ammonium metavanadate [NH ₄ VO ₃ ], antimony trioxide 0.887 kg of [Sb ₂ O ₃ ] was added and heated at 95 ° C. for 1 hour with stirring to obtain a liquid aqueous mixture (B ₁ ).
0.58 kg of hydrogen peroxide containing 30% by mass of H ₂ O ₂ was added to 3.826 kg of an Nb organic acid aqueous solution prepared in the same manner as in Example 1. While maintaining the liquid temperature at about 20 ° C., the mixture was stirred and mixed to obtain an Nb organic acid compound / complex forming agent aqueous solution.
After cooling the aqueous mixture (B ₁ ) to 70 ° C., 7.730 kg of silica sol containing 30.4% by mass of SiO ₂ was added. Next, 1.03 kg of hydrogen peroxide containing 30% by mass of H ₂ O ₂ was added and stirred and mixed at 50 ° C. for 1 hour, and then an Nb organic acid compound / complex forming agent aqueous solution was added. Further, a liquid in which 2.35 kg of fumed silica was dispersed in 32.9 kg of water and 0.059 kg of tantalum acid were sequentially added and stirred at 50 ° C. for 2.5 hours to obtain a raw material preparation liquid.
(Preparation and firing of dry powder (E ₁ ))
A dry powder (E ₁ ) was prepared in the same manner as in Example 1 except that the raw material preparation solution was used, and the dry powder (E ₁ ) was fired in the same manner as in Example 1 to obtain a fired body ( F ₁₎ was obtained.
(Removal of protrusions)
A protrusion was removed to prepare a composite oxide catalyst (G ₁ ) in the same manner as in Example 1 except that the fired body was used.
(Propane ammoxidation reaction)
Propane ammoxidation was carried out in the same manner as in Example 1 except that the composite oxide catalyst (G ₁ ) was used. The results are shown in Table 2.

(Example 21)
An oxide catalyst having a composition formula of Mo ₁ V _0.24 Nb _0.11 Sb _0.26 Ce _0.004 Bi _0.02 / 48 mass% -SiO ₂ was prepared as follows.
(Preparation of raw material mixture)
Into 19.8 kg of water in the container, 4.215 kg of ammonium heptamolybdate [(NH ₄ ) ₆ Mo ₇ O ₂₄ · 4H ₂ O], 0.666 kg of ammonium metavanadate [NH ₄ VO ₃ ], antimony trioxide 0.903 kg of [Sb ₂ O ₃ ] and 0.042 kg of cerium nitrate [Ce (NO3) 3.6H2O] were added and heated at 95 ° C. for 1 hour with stirring to obtain a liquid aqueous mixture (B ₁ ). .
To 3.892 kg of the Nb organic acid aqueous solution prepared in the same manner as in Example 1, 0.59 kg of hydrogen peroxide containing 30% by mass of H ₂ O ₂ was added. While maintaining the liquid temperature at about 20 ° C., the mixture was stirred and mixed to obtain an Nb organic acid compound / complex forming agent aqueous solution.
After cooling the aqueous mixture (B ₁ ) to 70 ° C., 7.73 kg of silica sol containing 30.4% by mass of SiO ₂ was added. Next, 1.05 kg of hydrogen peroxide containing 30% by mass of H ₂ O ₂ was added and stirred and mixed at 50 ° C. for 1 hour, and then an Nb organic acid compound / complex forming agent aqueous solution was added. Further, a solution obtained by dispersing 2.35 kg of fumed silica in 32.9 kg of water and 0.189 kg of bismuth nitrate [Bi (NO ₃ ) ₂ .6H ₂ O] were sequentially added, and the mixture was added at 50 ° C. The mixture was stirred for 5 hours to obtain a raw material preparation solution.
(Preparation and firing of dry powder (E ₁ ))
A dry powder (E ₁ ) was prepared in the same manner as in Example 1 except that the raw material preparation solution was used, and the dry powder (E ₁ ) was fired in the same manner as in Example 1 to obtain a fired body ( F ₁₎ was obtained.
(Removal of protrusions)
A protrusion was removed to prepare a composite oxide catalyst (G ₁ ) in the same manner as in Example 1 except that the fired body was used.
(Propane ammoxidation reaction)
Propane ammoxidation was carried out in the same manner as in Example 1 except that the composite oxide catalyst (G ₁ ) was used. The results are shown in Table 2.

(Example 22)
An oxide catalyst having a composition formula of Mo ₁ V _0.24 Nb _0.11 Sb _0.26 Yb _0.008 / 48 mass% -SiO ₂ was prepared as follows.
(Preparation of raw material mixture)
Into 19.8 kg of water in the container, 4.286 kg of ammonium heptamolybdate [(NH ₄ ) ₆ Mo ₇ O ₂₄ · 4H ₂ O], 0.677 kg of ammonium metavanadate [NH ₄ VO ₃ ], antimony trioxide 0.918 kg of [Sb ₂ O ₃ ] and 0.083 kg of ytterbium nitrate [Yb (NO ₃ ) ₃ .4H ₂ O] were added and heated at 95 ° C. for 1 hour with stirring to form a liquid aqueous mixture (B ₁ ) Got.
To 3.958 kg of the Nb organic acid aqueous solution prepared in the same manner as in Example 1, 0.60 kg of hydrogen peroxide containing 30% by mass of H ₂ O ₂ was added. While maintaining the liquid temperature at about 20 ° C., the mixture was stirred and mixed to obtain an Nb organic acid compound / complex forming agent aqueous solution.
After the aqueous mixture (B ₁ ) was cooled to 70 ° C., 7.781 kg of silica sol containing 30.2% by mass of SiO ₂ was added. Next, 1.07 kg of hydrogen peroxide containing 30% by mass of H ₂ O ₂ was added, and after stirring and mixing at 50 ° C. for 1 hour, an Nb organic acid compound / complexing agent aqueous solution was added. Furthermore, a liquid in which 2.35 kg of fumed silica was dispersed in 32.9 kg of water was added and stirred at 50 ° C. for 2.5 hours to obtain a raw material preparation liquid.
(Preparation and firing of dry powder (E ₁ ))
A dry powder (E ₁ ) was prepared in the same manner as in Example 1 except that the raw material preparation solution was used, and the dry powder (E ₁ ) was fired in the same manner as in Example 1 to obtain a fired body ( F ₁₎ was obtained.
(Removal of protrusions)
A protrusion was removed to prepare a composite oxide catalyst (G ₁ ) in the same manner as in Example 1 except that the fired body was used.
(Propane ammoxidation reaction)
Propane ammoxidation was carried out in the same manner as in Example 1 except that the composite oxide catalyst (G ₁ ) was used. The results are shown in Table 2.

(Example 23)
An oxide catalyst having a composition formula of Mo ₁ V _0.26 Nb _0.11 Sb _0.24 / 48 mass% -SiO ₂ was prepared as follows.
(Preparation of raw material mixture)
Into 19.8 kg of water in the container, 4.339 kg of ammonium heptamolybdate [(NH ₄ ) ₆ Mo ₇ O ₂₄ · 4H ₂ O], 0.743 kg of ammonium metavanadate [NH ₄ VO ₃ ], antimony trioxide 0.858 kg of [Sb ₂ O ₃ ] was added and heated at 95 ° C. for 1 hour with stirring to obtain a liquid aqueous mixture (B ₁ ).
To 4.006 kg of the Nb organic acid aqueous solution prepared in the same manner as in Example 1, 0.61 kg of hydrogen peroxide containing 30% by mass of H ₂ O ₂ was added. While maintaining the liquid temperature at about 20 ° C., the mixture was stirred and mixed to obtain an Nb organic acid compound / complex forming agent aqueous solution.
After the aqueous mixture (B ₁ ) was cooled to 70 ° C., 7.781 kg of silica sol containing 30.2% by mass of SiO ₂ was added. Next, 1.00 kg of hydrogen peroxide containing 30% by mass of H ₂ O ₂ was added and stirred and mixed at 50 ° C. for 1 hour, and then an Nb organic acid compound / complex forming agent aqueous solution was added. Furthermore, a liquid in which 2.35 kg of fumed silica was dispersed in 32.9 kg of water was added and stirred at 50 ° C. for 2.5 hours to obtain a raw material preparation liquid.
(Preparation and firing of dry powder (E ₁ ))
A dry powder (E ₁ ) was prepared in the same manner as in Example 1 except that the raw material preparation solution was used, and the dry powder (E ₁ ) was fired in the same manner as in Example 1 to obtain a fired body ( F ₁₎ was obtained.
(Removal of protrusions)
A protrusion was removed to prepare a composite oxide catalyst (G ₁ ) in the same manner as in Example 1 except that the fired body was used.
(Propane ammoxidation reaction)
Propane ammoxidation was carried out in the same manner as in Example 1 except that the composite oxide catalyst (G ₁ ) was used. The results are shown in Table 2.

(Example 24)
An oxide catalyst having a composition formula of Mo ₁ V _0.24 Nb _0.11 Sb _0.26 W _0.03 Ce _0.006 / 51 mass% -SiO ₂ was prepared as follows.
(Preparation of raw material mixture)
19.8 kg of water in the container is 3.93 kg of ammonium heptamolybdate [(NH ₄ ) ₆ Mo ₇ O ₂₄ · 4H ₂ O], 0.621 kg of ammonium metavanadate [NH ₄ VO ₃ ], antimony trioxide Add 0.842 kg of [Sb ₂ O ₃ ] and 0.059 kg of cerium nitrate [Ce (NO 3) 3 .6H ₂ O], and add a liquid aqueous mixture (B ₁ ) by heating at 95 ° C. for 1 hour with stirring. Got.
0.55 kg of hydrogen peroxide containing 30% by mass of H ₂ O ₂ was added to 3.629 kg of an Nb organic acid aqueous solution prepared in the same manner as in Example 1. While maintaining the liquid temperature at about 20 ° C., the mixture was stirred and mixed to obtain an Nb organic acid compound / complex forming agent aqueous solution.
After cooling the aqueous mixture (B ₁ ) to 70 ° C., 8.278 kg of silica sol containing 30.2 mass% SiO ₂ was added. Next, 0.98 kg of hydrogen peroxide containing 30% by mass of H ₂ O ₂ was added and stirred and mixed at 50 ° C. for 1 hour, and then an Nb organic acid compound / complex forming agent aqueous solution was added. Furthermore, 0.327 kg of ammonium metatungstate containing 50% by weight of WO ₃ and 0.307 kg of ammonium metatungstate containing 50% by weight of WO ₃ were added and stirred at 50 ° C. for 2.5 hours. A raw material mixture was obtained.
(Preparation and firing of dry powder (E ₁ ))
A dry powder (E ₁ ) was prepared in the same manner as in Example 1 except that the raw material preparation solution was used, and the dry powder (E ₁ ) was fired in the same manner as in Example 1 to obtain a fired body ( F ₁₎ was obtained.
(Removal of protrusions)
A protrusion was removed to prepare a composite oxide catalyst (G ₁ ) in the same manner as in Example 1 except that the fired body was used.
(Propane ammoxidation reaction)
Propane ammoxidation was carried out in the same manner as in Example 1 except that the composite oxide catalyst (G ₁ ) was used. The results are shown in Table 2.

  ADVANTAGE OF THE INVENTION According to this invention, the melt | dissolution time and filtration time of Nb raw material compound can be shortened, the clogging at the time of filtration can be prevented, and the liquid containing an organic acid and Nb raw material compound can be manufactured efficiently with sufficient productivity. Further, the niobium concentration in the liquid containing the organic acid and the Nb raw material compound can be increased. Also in the subsequent catalyst preparation using the liquid containing the organic acid and Nb raw material compound of the present invention, the liquid concentration can be easily adjusted, so that catalyst particles having a desired spherical shape can be obtained. Therefore, it has industrial applicability in the field of gas phase catalytic oxidation and / or ammoxidation catalyst production containing niobium.

Claims (11)

A method for producing an oxide catalyst used in the production of an unsaturated acid or an unsaturated nitrile, comprising the step of mixing an Nb raw material compound, an organic acid and water to obtain an Nb aqueous mixture, Nb remaining渣率is Ri der less than 5.0%,
The Nb raw material compound is niobic acid,
The manufacturing method of an oxide catalyst whose average particle diameter of the said Nb raw material compound is 1.0-100 micrometers . Wherein the organic acid is at least one selected from the group consisting of dicarboxylic acids and their anhydrides or hydrate method according to claim 1. Filtering the Nb aqueous mixture to obtain an aqueous Nb organic acid solution;
Mixing the Nb organic acid aqueous solution with a complexing agent or an aqueous solution of a complexing agent to obtain an Nb organic acid compound / complexing agent aqueous solution;
The manufacturing method of Claim 1 or 2 which has these. The production method according to claim 3 , wherein the complexing agent is at least one compound selected from the group consisting of hydrogen peroxide and monooxypolycarboxylic acids. The Nb organic acid compound / complex forming agent aqueous solution contains one or more kinds of compounds containing one or more elements selected from the group consisting of metal elements and metalloid elements other than niobium contained in the oxide catalyst. The manufacturing method of Claim 3 or 4 which has the process of mixing with an aqueous mixture and obtaining a catalyst raw material preparation liquid. Drying the catalyst raw material preparation liquid to obtain a dried product;
Firing the dried body;
The manufacturing method of Claim 5 which has these. The oxide catalyst includes an oxide of one or more elements selected from the group consisting of a metal element and a metalloid element and an oxide of the metalloid element, and the oxide of the one or more elements and the metalloid The oxide of the one or more elements is supported on 10 to 80 mass% of the oxide of the metalloid element in terms of the oxide of the metalloid element relative to the total mass of the oxide of the element. The manufacturing method of any one of Claims 1-6 . The production method according to claim 7 , wherein the oxide of the metalloid element is silica. The manufacturing method according to any one of claims 1 to 8 , wherein the oxide catalyst contains Mo, V, Sb, and Nb. Propane or isobutane, the vapor-phase catalytic oxidation reaction, a process for the preparation of unsaturated acids to produce the corresponding unsaturated acid, in any one of claims 1 to 9 as catalyst for the gas-phase catalytic oxidation reaction The manufacturing method of an unsaturated acid using the oxide catalyst obtained by the manufacturing method of description. Propane or isobutane, the vapor-phase catalytic ammoxidation reaction, a method for producing an unsaturated nitrile to produce the corresponding unsaturated nitrile, claim 1-9 as a catalyst for the vapor phase catalytic ammoxidation 1 A method for producing an unsaturated nitrile, using the oxide catalyst obtained by the production method according to the item.