JP5609285B2 - Method for producing composite oxide catalyst - Google Patents

Description

  The present invention relates to a method for producing a composite oxide catalyst containing iron, antimony, and silica.

  Antimony-containing composite oxide catalysts are widely known as catalysts suitable for the production of aldehydes and unsaturated acids by the oxidation reaction of organic compounds and the production of nitriles and hydrocyanic acid by an ammoxidation reaction. In particular, the antimony-containing composite oxide catalyst is useful for an ammoxidation reaction, and is used, for example, for the production of acrylonitrile by an ammoxidation reaction of propylene or the production of hydrocyanic acid by an ammoxidation reaction of methanol.

  By the way, acrylonitrile is industrially synthesized by a method widely known as a “fluidized bed ammoxidation process”. In this fluidized bed ammoxidation process, if the mechanical strength of the catalyst is low, the catalyst may be destroyed or worn, and stable operation may not be continued. Therefore, the catalyst is more preferable as it has better mechanical strength, and a technique for improving the mechanical strength of the catalyst is required.

Conventionally, many studies have been made on catalysts used in oxidation reactions and ammoxidation reactions, and various catalysts have been proposed so far.
For example, Patent Document 1 discloses a composite oxide catalyst of antimony and at least one element selected from the group consisting of iron, cobalt, and nickel.
For example, Patent Documents 2 to 11 disclose catalysts in which tellurium, vanadium, tungsten, molybdenum, phosphorus, or the like is added to iron or antimony.

Furthermore, investigations for improving the yield of the target product by improving the catalyst preparation method are continued. For example, Patent Documents 12 to 16 disclose a method for adjusting the pH of a slurry containing antimony and a polyvalent metal compound, a method for heat-treating the slurry, and the like.
As a technique for improving the mechanical strength of the catalyst, for example, Patent Document 17 discloses a method of using silica sol and fumed silica as raw materials in an improved preparation method of an acrylonitrile synthesis catalyst mainly composed of antimony. ing.

Japanese Examined Patent Publication No. 38-19111 Japanese Patent Publication No.46-2804 Japanese Patent Publication No. 47-19765 Japanese Patent Publication No. 47-19766 Japanese Patent Publication No.47-19767 JP 50-108219 A JP 58-145617 A JP-A-1-257125 JP-A-3-26342 JP-A-4-118051 JP 2001-114740 A Japanese Patent Publication No.47-18722 JP 49-40288 A Japanese Patent Laid-Open No. 52-140490 JP-A-60-137438 JP-A-1-265068 JP 58-11045 A

  However, catalysts produced using the methods disclosed in these patent documents are not necessarily industrial catalysts although some effects are seen in physical properties such as improvement in yield of the target product and mechanical strength of the catalyst. As a result, further improvement in catalyst performance is desired.

  This invention is made | formed in view of the said situation, and it aims at providing the manufacturing method of the complex oxide catalyst which is excellent in mechanical strength and can manufacture a target product with a high yield.

The method for producing a composite oxide catalyst of the present invention is a method for producing a composite oxide catalyst containing iron, antimony, and silica, wherein at least a part of iron, antimony, and silica is mixed to obtain a mixed slurry. Preparing and heat-treating this mixed slurry, and adding to the mixed slurry after the heat treatment 3 to 80% of silica in a molar fraction with respect to the total amount of silica used for catalyst production. seen, before Symbol composite oxide catalyst, characterized by having a composition represented by the following formula (I).
Fe ₁₀ Sb _i A _a D _d E _e G _g O _x (SiO ₂ ) _y (I)

Where Fe, Sb, and SiO ₂ represent iron, antimony, and silica, respectively, A is nickel, copper, aluminum, manganese, zinc, tin, chromium, cobalt, magnesium, calcium, strontium, lead, barium, niobium , At least one element selected from the group consisting of silver, zirconium, gallium, indium, thallium, titanium, and bismuth, D is at least one element selected from the group consisting of vanadium, molybdenum, and tungsten, and E is phosphorus At least one element selected from the group consisting of arsenic, boron, germanium, and tellurium, G represents at least one element selected from the group consisting of lithium, sodium, potassium, rubidium, and cesium, and O represents oxygen , I, a, d, e, g, x, and y represents the atomic ratio of each element (silicon in the case of silica), and when Fe = 10, i = 3 to 100, a = 0.1 to 20, d = 0 to 15, e = 0 to 20, g = 0 to 3, x = number of oxygen in the metal oxide formed by combining the above components, y = 10 to 200.

  ADVANTAGE OF THE INVENTION According to this invention, it is excellent in mechanical strength and can provide the manufacturing method of the composite oxide catalyst which can manufacture a target product with a high yield.

Hereinafter, the present invention will be described in detail.
The method for producing a composite oxide catalyst of the present invention (hereinafter sometimes referred to as “the catalyst production method of the present invention”) is a method for producing a composite oxide catalyst containing iron, antimony, and silica, and includes at least Then, iron, antimony, and a part of silica are mixed to prepare a mixed slurry, and the mixed slurry is subjected to heat treatment, and the mixed slurry after the heat treatment is mixed with the total amount of silica used for catalyst production. It includes a step of adding silica in an amount of 3 to 80% in a fraction.

In the catalyst production method of the present invention, first, a catalyst raw material containing at least iron, antimony, and a part of silica is mixed to prepare a mixed slurry before heat treatment.
There are no restrictions on the mixing conditions and mixing order of the catalyst raw materials when preparing the mixed slurry before the heat treatment.

Although it does not restrict | limit especially about the catalyst raw material of each component used for a catalyst manufacturing method, What is shown below is mentioned.
Examples of the raw material for the iron component include ferrous oxide, ferric oxide, ferrous nitrate, ferric nitrate, iron sulfate, iron chloride, iron organic acid salt, and iron hydroxide. In addition, metallic iron may be dissolved in heated nitric acid.

  As the raw material of the antimony component, for example, oxides such as antimony trioxide and antimony pentoxide, antimony chloride, antimony sulfate and the like can be used.

As a raw material for the silica component, silica sol is preferable, which can be appropriately selected from commercially available ones.
The size of the silica particles in the silica sol is not particularly limited, but the average particle diameter is preferably 2 to 100 nm, more preferably 5 to 75 nm. The silica sol may have a uniform silica particle size or may be a mixture of silica particles of several sizes. Further, a plurality of types of silica sols having different average particles and pH may be mixed and used.
Here, the average particle diameter of the silica particles is a value obtained from the adsorption amount of nitrogen adsorbed on the surface of the silica particles by the BET method.

When the composite oxide catalyst to be produced by the catalyst production method of the present invention contains other catalyst components other than iron, antimony, and silica, these catalyst components are contained in the mixed slurry before the heat treatment. It may or may not be included. Moreover, you may add to the mixed slurry after the heat processing mentioned later.
There are no particular restrictions on the raw materials for these catalyst components, and oxides of each element, or chlorides, sulfates, nitrates, ammonium salts, carbonates, hydroxides, and organic acid salts that can easily become oxides upon heating. , Oxygen acids, oxyacid salts, heteropolyacids, heteropolyacid salts, or mixtures thereof can be used. Moreover, you may use these in combination of multiple types.

  There is no restriction | limiting also about the solvent used when preparing a mixing slurry, For example, although water, ethyl alcohol, acetone, etc. are mentioned, it is preferable to use water. Further, an acid such as nitric acid, sulfuric acid or hydrochloric acid, or an alkaline solution such as aqueous ammonia may be added to the solvent.

Next, the mixed slurry is heated. Here, the heat treatment of the mixed slurry refers to a step of holding the mixed slurry at a temperature of 80 ° C. or higher for 30 minutes or longer.
The lower limit of the heat treatment temperature is preferably 85 ° C or higher, more preferably 90 ° C or higher, and the upper limit is not particularly limited, but is generally 120 ° C or lower. When the lower limit of the heat treatment temperature is less than 80 ° C., the iron-antimony crystal phase considered to be advantageous for producing the target product is insufficiently produced, and the yield of the target product is lowered.
The heat treatment time can be performed in the range of 30 minutes to 72 hours. When the heat treatment time is less than 30 minutes, the production of an iron-antimony crystal phase considered to be advantageous for producing the target product becomes insufficient, and the effect of the heat treatment cannot be sufficiently obtained. On the other hand, even if the heat treatment time exceeds 72 hours, the obtained effect reaches a peak.
The pressure during the heat treatment is usually performed under normal pressure, but is not particularly limited. If necessary, the heat treatment may be performed under reduced pressure or under pressure.

Next, the raw material of the silica component is added to the mixed slurry after the heat treatment.
When using the raw material of a multiple types of silica component, you may add separately to the mixed slurry after heat processing, and may add together.
There are no restrictions on the addition conditions and order of addition of the silica component raw material to the mixed slurry after the heat treatment.

  It is important that the ratio of the amount of silica added to the mixed slurry after the heat treatment is in the range of 3 to 80% in terms of molar fraction with respect to the total amount of silica used for catalyst production, and the lower limit is 5% or more. The upper limit is preferably 70% or less, and more preferably 60% or less.

If the ratio of the amount of silica added to the mixed slurry after the heat treatment is 3% or more in terms of a molar fraction with respect to the total amount of silica used for catalyst production, the mechanical strength of the resulting catalyst will be improved.
On the other hand, if the ratio of the amount of silica added to the mixed slurry after the heat treatment is 80% or less in terms of molar fraction with respect to the total amount of silica used for catalyst production, a catalyst capable of producing the target product in high yield is obtained. can get.

Further, when the composite oxide catalyst to be produced by the catalyst production method of the present invention contains other catalyst components other than iron, antimony, and silica, the raw materials of these catalyst components are mixed into the mixed slurry after the heat treatment. It may be added. There are no restrictions on the addition conditions and order of addition.
The mixed slurry does not necessarily contain the necessary amount of all the elements constituting the catalyst. Elemental components not contained in the mixed slurry or raw materials of elemental components that do not reach the necessary amount May be added in each step before the drying step described later, or may be added by a method such as impregnating the catalyst after drying.

Next, in the drying step, the slurry after adding silica to the mixed slurry after the heat treatment is dried to obtain a dried product (catalyst precursor).
The composite oxide catalyst produced by the catalyst production method of the present invention is preferably used as a fluidized bed catalyst, and in that case, it is preferred to form spherical particles by spray drying. At the time of spray drying, a spray dryer such as a pressure nozzle type, a two-fluid nozzle type, and a rotary disk type is used.

At the time of spray drying, the temperature of the hot air circulated in the drying chamber of the spray dryer is preferably 130 ° C. or higher, more preferably 140 ° C. or higher, and preferably the upper limit of the temperature in the vicinity of the inlet to the drying chamber. Is 400 ° C. or lower, more preferably 350 ° C. or lower. Further, the lower limit of the temperature in the vicinity of the drying chamber outlet is preferably 100 ° C. or higher, more preferably 110 ° C. or higher, and the upper limit is preferably 220 ° C. or lower, more preferably 200 ° C. or lower. Furthermore, the difference between the temperature in the vicinity of the inlet and the temperature in the vicinity of the drying chamber outlet is preferably maintained at 20 to 220 ° C, more preferably 30 to 210 ° C.
When each of the above temperatures is not within a predetermined range, the activity of the obtained catalyst and the yield of the target product are reduced, the bulk density of the catalyst, the mechanical strength of the catalyst, etc. are reduced. May occur.

Next, in the firing step, the dried product (catalyst precursor) is fired to obtain a composite oxide catalyst containing iron, antimony, and silica.
In the present invention, the firing is preferably carried out in two or more times. By performing the baking in two or more times, the target product yield is more likely to be improved.
When the final firing is the final firing, and the preliminary firing is performed prior to the final firing, the lower temperature limit of the final firing is preferably 550 ° C. or higher, more preferably 570 ° C. or higher, and the upper limit is preferably It is 1100 degrees C or less, More preferably, it is 1000 degrees C or less. If the temperature is lower than the lower limit, sufficient catalytic performance may not be exhibited, and the target product yield may be reduced. On the other hand, if it is higher than the upper limit, the yield of the target product may be reduced, or the activity of the catalyst may be excessively low. Further, in the ammoxidation reaction, ammonia combustibility is remarkably increased, and the ammonia basic unit may be lowered, which is not preferable.

  Further, the lower limit of the final firing time is preferably 0.1 hour or longer, more preferably 0.5 hour or longer. If the calcination time is shorter than the lower limit, sufficient catalyst performance may not be exhibited, and the target product yield may decrease. The upper limit is not particularly limited, but the effect obtained even if the time is extended more than necessary does not become a certain level, and is usually within 20 hours.

On the other hand, the temperature for temporary baking is preferably in the range of 200 to 490 ° C.
A general-purpose firing furnace can be used for final firing and temporary firing, but a rotary kiln, fluidized firing furnace, and the like are particularly preferably used. The gas atmosphere used at this time may be an oxidizing gas atmosphere containing oxygen or an inert gas atmosphere such as nitrogen, but it is convenient to use air.

The average particle size of the catalyst thus produced is preferably in the range of 5 to 200 μm, more preferably in the range of 10 to 150 μm. In order to make the particle size distribution of the resulting catalyst within a desired range, the spray drying conditions may be adjusted as appropriate.
The average particle diameter of the catalyst is a value (average median diameter) measured by a laser diffraction / scattering method.

The composite oxide catalyst produced by the catalyst production method of the present invention is not particularly limited as long as it contains at least iron, antimony, and silica, but has a composition represented by the following general formula (I). Is preferred. If the catalyst is a composition represented by the following general formula (I), the effects of the present invention will be sufficiently manifested, for example, the target product yield will be improved.
Fe ₁₀ Sb _i A _a D _d E _e G _g O _x (SiO ₂ ) _y (I)

Where Fe, Sb, and SiO ₂ represent iron, antimony, and silica, respectively, A is nickel, copper, aluminum, manganese, zinc, tin, chromium, cobalt, magnesium, calcium, strontium, lead, barium, niobium , At least one element selected from the group consisting of silver, zirconium, gallium, indium, thallium, titanium, and bismuth, D is at least one element selected from the group consisting of vanadium, molybdenum, and tungsten, and E is phosphorus At least one element selected from the group consisting of arsenic, boron, germanium, and tellurium, G represents at least one element selected from the group consisting of lithium, sodium, potassium, rubidium, and cesium, and O represents oxygen , I, a, d, e, g, x, and y represents the atomic ratio of each element (silicon in the case of silica), and when Fe = 10, i = 3 to 100, a = 0.1 to 20, d = 0 to 15, e = 0 to 20, g = 0 to 3, x = number of oxygen in the metal oxide formed by combining the above components, y = 10 to 200.

  In order to make the catalyst have the above-mentioned composition, for example, a method of appropriately selecting the amount of the catalyst raw material added when preparing the mixed slurry, or an appropriate amount of raw material added in the steps from preparation of the mixed slurry to firing The method of doing is mentioned.

  The composition of the catalyst can be confirmed by conducting elemental analysis by ICP (inductively coupled radio frequency plasma) emission analysis, fluorescent X-ray analysis, atomic absorption analysis or the like. In the case where an extremely volatile element is not used, it may be calculated from the amount of each raw material used at the time of catalyst production.

  Thus, according to the present invention, by determining the timing and amount of silica addition in the process of producing the catalyst, that is, mixing iron, antimony and a part of silica to prepare a mixed slurry, After this mixed slurry is heat-treated, it is surprising to add 3 to 80% of silica in a molar fraction with respect to the total amount of silica used for catalyst production. In addition, a composite oxide catalyst having excellent mechanical strength and capable of producing a target product with high yield can be obtained.

  The mechanical strength of the catalyst can be evaluated by measuring the compressive strength of the catalyst using a measuring machine such as a compressive strength tester. In addition, for the measurement of compressive strength, a catalyst sieved to 45 to 50 μm is usually used in many cases. At this time, it is sufficient to measure about about 50 arbitrarily selected catalysts.

  In order to produce nitriles and the like by an ammoxidation reaction of an organic compound using the composite oxide catalyst produced according to the present invention, it is preferable to use a fluidized bed reactor. This can be carried out by filling the fluidized bed reactor with a composite oxide catalyst and supplying a raw material gas containing a raw material organic compound, ammonia, and oxygen to the catalyst layer.

Although it does not specifically limit as source gas, The source gas of the range whose organic compound / ammonia / oxygen is 1 / 1.1-1.5 / 1.5-3 (molar ratio) is preferable.
It is convenient to use air as the oxygen source. The source gas may be used after being diluted with an inert gas such as water vapor, nitrogen or carbon dioxide, saturated hydrocarbon or the like, or may be used with an increased oxygen concentration.
The reaction temperature of the ammoxidation reaction is preferably 370 to 500 ° C., and the reaction pressure is preferably within the range of normal pressure to 500 kPa.
The apparent contact time is preferably 0.1 to 20 seconds.

EXAMPLES Hereinafter, although an Example and a comparative example demonstrate this invention concretely, this invention is not limited to an Example.
In the following examples and comparative examples, “parts” means parts by mass.
In addition, the composition of the catalyst obtained by the Example and the comparative example was calculated | required from the preparation amount of each raw material used for manufacture of a catalyst.
Moreover, the activity test of the catalyst obtained in each example and evaluation of mechanical strength were implemented in the following procedures.

(1) Catalyst activity test In order to evaluate the activity of the catalyst, acrylonitrile was produced by the ammoxidation reaction of propylene in the following manner.
A fluidized bed reactor having an inner diameter of 55 mm and a height of 2000 mm in the catalyst fluidized part was filled with the catalyst so that the apparent contact time between the catalyst and the raw material gas was as shown in Table 1. The contact time in that case was calculated | required by the following formula.
Contact time (seconds) = apparent volume density based catalyst volume (mL) / feed gas amount converted to reaction conditions (mL / second)

Air was used as an oxygen source, and a raw material gas having a composition of propylene: ammonia: oxygen = 1: 1.1: 2.3 (molar ratio) was fed into the catalyst layer at a gas linear velocity of 17 cm / sec. The reaction pressure was 200 kPa, and the reaction temperature was 460 ° C.
Gas chromatography was used to quantify the reaction product, and the propylene conversion rate and acrylonitrile yield 4 hours after the start of the reaction were determined. The propylene conversion rate and acrylonitrile yield at that time were determined by the following formula.
Propylene conversion rate (%) = {(carbon mass of supplied propylene−carbon mass of unreacted propylene) / carbon mass of supplied propylene} × 100
Acrylonitrile yield (%) = (carbon mass of produced acrylonitrile / carbon mass of supplied propylene) × 100

(2) Evaluation of the mechanical strength of the catalyst About 50 catalysts arbitrarily collected from the sieved 45-50 μm catalyst, using a compressive strength tester (“Shimadzu MCTM-200” manufactured by Shimadzu Corporation), the following: The individual compressive strength was measured under the measurement conditions, and the average value was taken as the mechanical strength of the catalyst.
・ Upper pressure indenter: (500 μm flat indenter made of diamond)
・ Lower pressure plate: SUS plate ・ Loading speed: 7.1 mN / sec

[Example 1]
The catalyst was produced by the following procedure.
In 4000 parts of 63 mass% nitric acid, 383.7 parts of iron powder was dissolved. While stirring, 3000 parts of pure water was added to this solution. After heating this solution to 60 ° C., a molybdenum solution in which 121.3 parts of ammonium paramolybdate was dissolved in 6536.0 parts of 30% by mass silica, 1802.7 parts of antimony trioxide powder, and 200 parts of pure water was sequentially added. A mixed slurry was prepared.
15% by mass aqueous ammonia was added to the mixed slurry to adjust to pH 2.2, and the resulting mixed slurry was heated at 98 ° C. for 4 hours under reflux.
Subsequently, the mixed slurry after the heat treatment is cooled to 80 ° C., and 332.0 parts of copper nitrate trihydrate, 123.7 parts of chromium nitrate nonahydrate, 99.9 parts of nickel nitrate hexahydrate Then, 5.1 parts of rubidium nitrate, 63.4 parts of 85% by weight phosphoric acid, 63.7 parts of boric acid, 220.9 parts of telluric acid, and 344.0 parts of 30% by weight silica were sequentially added. The ratio of the amount of silica added to the mixed slurry after the heat treatment was 5% in terms of molar fraction with respect to the total amount of silica used in the production of the catalyst.
The mixed slurry was atomized using a homogenizer.
The mixed slurry after the atomization treatment was dried by a spray drier to obtain spherical dry particles. Next, the obtained dry particles were calcined at 250 ° C. for 2 hours and at 450 ° C. for 2 hours, and finally fluidly calcined at 750 ° C. for 4 hours using a fluidized calciner to obtain a catalyst.
The composition of the obtained catalyst was as follows.
Fe ₁₀ Sb ₁₈ Cu ₂ Cr _0.45 Ni _0.5 Mo _1.0 P _0.8 B _1.5 Te _1.4 Rb _0.05 O _x (SiO ₂ ) ₅₀
Here, x is the number of oxygen in the metal oxide formed by combining the above components.

  The obtained catalyst was subjected to an activity test. The contact time was 2.7 seconds. Further, the mechanical strength shown in (2) was evaluated for the catalyst after the activity test. The results are shown in Table 1.

[Example 2]
Example 1 except that the amount of silica used in the preparation of the mixed slurry before the heat treatment was changed to 5160.0 parts and the amount of silica added to the mixed slurry after the heat treatment was changed to 1720.0 parts in Example 1. A catalyst was produced in the same manner as above, and each evaluation was performed. The results are shown in Table 1.
In the production of this catalyst, the ratio of the amount of silica added to the mixed slurry after the heat treatment was 25% in terms of molar fraction with respect to the total amount of silica used in the production of the catalyst.

[Example 3]
The catalyst was produced by the following procedure.
A nitric acid solution was prepared by adding 3000 parts of 63 mass% nitric acid to 3000 parts of pure water being stirred. After heating this nitric acid solution to 60 ° C., 2953.7 parts of ferric nitrate nonahydrate was added and dissolved. This solution was mixed with molybdenum-vanadium in which 4200.4 parts by weight of silica, 1865.0 parts of antimony trioxide powder, 56.8 parts of ammonium paramolybdate and 0.86 parts of ammonium metavanadate were dissolved in 200 parts of pure water. The solution and 84.8 parts of a 50 mass% ammonium metatungstate solution were sequentially added to prepare a mixed slurry.
15% by mass aqueous ammonia was added to the mixed slurry to adjust to pH 2.2, and the resulting mixed slurry was heated at 98 ° C. for 4 hours under reflux.
Next, the mixed slurry after the heat treatment was cooled to 80 ° C., 42.5 parts of nickel nitrate hexahydrate, 53.0 parts of copper nitrate trihydrate, 28.1 parts of magnesium nitrate, 85 mass% phosphorus 227.6 parts of acid, 302.2 parts of telluric acid, and 741.2 parts of 40% by mass silica were sequentially added. The ratio of the amount of silica added to the mixed slurry after the heat treatment was 15% in terms of molar fraction with respect to the total amount of silica used in the production of the catalyst.
The mixed slurry was atomized using a homogenizer.
The mixed slurry after the atomization treatment was dried by a spray drier to obtain spherical dry particles. Next, the obtained dry particles were calcined at 250 ° C. for 2 hours and 450 ° C. for 2 hours, and finally fluidly calcined at 800 ° C. for 4 hours using a fluid calcining furnace to obtain a catalyst.
The composition of the obtained catalyst was as follows.
Fe ₁₀ Sb _17.5 Ni _0.2 Cu _0.3 Mg _0.15 Mo _0.44 W _0.25 V _0.01 Te _1.8 P _2.7 O _x (SiO ₂ ) ₄₅
Here, x is the number of oxygen in the metal oxide formed by combining the above components.

  The obtained catalyst was subjected to an activity test. The contact time was 2.8 seconds. Further, the mechanical strength shown in (2) was evaluated for the catalyst after the activity test. The results are shown in Table 1.

[Example 4]
In Example 3, the amount of silica used for the preparation of the mixed slurry before the heat treatment was changed to 2470.8 parts, and the amount of silica added to the mixed slurry after the heat treatment was changed to 2470.8 parts. A catalyst was produced in the same manner as above, and each evaluation was performed. The results are shown in Table 1.
In the production of this catalyst, the ratio of the amount of silica added to the mixed slurry after the heat treatment was 50% in terms of molar fraction with respect to the total amount of silica used in the production of the catalyst.

[Comparative Example 1]
In Example 1, the amount of silica used for the preparation of the mixed slurry before the heat treatment was changed to 6880.0 parts, and the catalyst was the same as in Example 1 except that no silica was added to the mixed slurry after the heat treatment. Were manufactured and each evaluation was carried out. The results are shown in Table 1.
In the production of this catalyst, the ratio of the amount of silica added to the mixed slurry after the heat treatment was 0% in terms of molar fraction with respect to the total amount of silica used in the production of the catalyst.

[Comparative Example 2]
In Example 1, a catalyst was produced in the same manner as in Example 1 except that silica was not used for preparation of the mixed slurry before the heat treatment, and the amount of silica added to the mixed slurry after the heat treatment was changed to 6880.0 parts. Each evaluation was conducted. The results are shown in Table 1.
In the production of this catalyst, the ratio of the amount of silica added to the mixed slurry after the heat treatment was 100% in terms of mole fraction with respect to the total amount of silica used in the production of the catalyst.

[Comparative Example 3]
In Example 3, the amount of silica used for the preparation of the mixed slurry before the heat treatment was changed to 4892.2 parts, and the amount of silica added to the mixed slurry after the heat treatment was changed to 49.4 parts, Example 3 A catalyst was produced in the same manner as above, and each evaluation was performed. The results are shown in Table 1.
In the production of this catalyst, the ratio of the amount of silica added to the mixed slurry after the heat treatment was 1% in terms of mole fraction with respect to the total amount of silica used in the production of the catalyst.

[Comparative Example 4]
In Example 3, the amount of silica used for the preparation of the mixed slurry before the heat treatment was changed to 247.1 parts, and the amount of silica added to the mixed slurry after the heat treatment was changed to 4694.5 parts, Example 3 A catalyst was produced in the same manner as above, and each evaluation was performed. The results are shown in Table 1.
In the production of this catalyst, the ratio of the amount of silica added to the mixed slurry after the heat treatment was 95% in terms of molar fraction with respect to the total amount of silica used in the production of the catalyst.

As is clear from Table 1, all of the composite oxide catalysts obtained in Examples 1 to 4 had high catalyst mechanical strength and were able to produce acrylonitrile in a high yield.
On the other hand, although the composite oxide catalyst obtained in Comparative Example 1 has the same composition as the composite oxide catalyst obtained in Examples 1 and 2, it is compared with the catalyst obtained in Examples 1 and 2. Although there was no problem in terms of the yield of acrylonitrile, the mechanical strength of the catalyst was low.
In addition, the composite oxide catalyst obtained in Comparative Example 2 was compared with the catalyst obtained in Examples 1 and 2 even though the composite oxide catalyst obtained in Examples 1 and 2 had the same composition. Although there was no problem in terms of the mechanical strength of the catalyst, the yield of acrylonitrile was low.

Similarly, although the composite oxide catalyst obtained in Comparative Example 3 has the same composition as the composite oxide catalyst obtained in Examples 3 and 4, the catalyst obtained in Examples 3 and 4 In comparison, there was no problem in terms of the yield of acrylonitrile, but the mechanical strength of the catalyst was low.
Further, the composite oxide catalyst obtained in Comparative Example 4 was the same as the composite oxide catalyst obtained in Examples 3 and 4, but compared with the catalyst obtained in Examples 3 and 4. Although there was no problem in terms of the mechanical strength of the catalyst, the yield of acrylonitrile was low.

  The composite oxide catalyst produced according to the present invention has high mechanical strength of the catalyst, and has a high yield in the production of aldehydes and unsaturated acids by oxidation reaction of organic compounds, and in the production of nitriles and hydrocyanic acid by ammoxidation reaction. The desired product can be produced. Therefore, its industrial value is great.

Claims (1)

A method for producing a composite oxide catalyst containing iron, antimony, and silica, comprising:
At least a step of mixing iron, antimony, and a part of silica to prepare a mixed slurry, and heat-treating the mixed slurry;
The mixed slurry after the heat treatment, the total amount of silica used in the catalyst preparation, see contains the step of adding from 3 to 80% of the amount of silica in a molar fraction,
The said complex oxide catalyst has a composition represented by following formula (I), The manufacturing method of the complex oxide catalyst characterized by the above-mentioned.
Fe ₁₀ Sb _i A _a D _d E _e G _g O _x (SiO ₂ ) _y (I)
(Wherein Fe, Sb, and SiO ₂ represent iron, antimony, and silica, respectively, and A represents nickel, copper, aluminum, manganese, zinc, tin, chromium, cobalt, magnesium, calcium, strontium, lead, barium, At least one element selected from the group consisting of niobium, silver, zirconium, gallium, indium, thallium, titanium, and bismuth, D is at least one element selected from the group consisting of vanadium, molybdenum, and tungsten, E is At least one element selected from the group consisting of phosphorus, arsenic, boron, germanium, and tellurium, G is at least one element selected from the group consisting of lithium, sodium, potassium, rubidium, and cesium, and O is oxygen. I, a, d, e, g, x, and Y represents the atomic ratio of each element (silicon in the case of silica), and when Fe = 10, i = 3 to 100, a = 0.1 to 20, d = 0 to 15, e = 0 to 20, (g = 0-3, x = number of oxygen in the metal oxide produced by combining the above components, y = 10-200)