JP4606897B2 - Method for producing composite oxide catalyst for fluidized bed ammoxidation process - Google Patents

Description

  The present invention relates to a method for producing a composite oxide catalyst used in a fluidized bed ammoxidation process used for producing acrylonitrile and the like.

The ammoxidation process is a method in which olefins such as propylene, paraffins, alkyl-substituted aromatic compounds, etc. are brought into contact with a catalyst (gas phase contact) together with ammonia and molecular oxygen (air) and reacted. Currently, acrylonitrile, methacrylo It is widely used for industrial synthesis of nitriles such as nitriles.
As a catalyst used for the ammoxidation process, many proposals have been made so far, and a composite oxide catalyst containing oxides of two or more elements is mainly used. For example, Patent Documents 1 to 6 disclose composite oxide catalysts mainly composed of molybdenum and bismuth. These proposals mainly relate to technologies for improving so-called catalytic properties such as activity and selectivity. Mainly, in order to obtain a catalyst with a high acrylonitrile yield, the constituent elements and composition ratio of the composite oxide catalyst Is specified.

As one of the ammoxidation processes, there is known a fluidized bed (fluidized bed) ammoxidation process in which a particulate catalyst (catalyst particles) is reacted in a fluidized state in an apparatus.
In the fluidized bed ammoxidation process, various proposals have been made regarding the particle size of the catalyst particles in order to suppress catalyst loss during the reaction or to achieve a good fluidized state of the catalyst particles. For example, Patent Document 7 discloses that in a method for producing a fluidized bed ammoxidation reaction catalyst containing antimony as a main component, particles having a particle size of less than 20 μm are 5 mass% or less, and particles having a particle size of 200 μm or more. A method of adjusting to 15% by mass or less is disclosed. Patent Document 8 discloses a method in which the target nitriles can be obtained in a high yield and the catalyst loss can be reduced, and the content of particles having a particle size of 5 to 150 μm is 95% by mass or more. There is disclosed a catalyst in which the content of particles having a particle diameter of 20 to 30 μm is 3 to 30% by mass. Patent Document 9 discloses a method for producing a molybdenum-bismuth-iron-containing metal oxide fluidized bed catalyst as a method for reusing particles outside the desired particle size range generated when adjusting the particle size of the catalyst particles without waste. Proposed a method of spray drying the slurry containing the catalyst component to pulverize the dried product outside the desired particle size range generated in the step of obtaining catalyst particles, mixing it with the slurry before spray drying, and then spray drying again Has been.
According to these proposals, catalyst particles having a small particle size, particularly particles having a particle size of less than 20 μm, have a small mass, so that they are easily entrained by the reaction gas and scattered outside the reactor, and are difficult to be used effectively for the catalytic reaction. In addition, the catalyst particles having a large particle diameter, particularly those having a particle diameter of 150 μm or more or 200 μm or more, have a large mass, so that they do not flow easily in the reactor and are difficult to be used effectively for the catalytic reaction. Is.
In these proposals, catalyst particles having a desired particle size range are obtained by adjusting the particle size by classification or the like and separating particles outside the desired particle size range in a subsequent step.
Japanese Patent Publication No. 61-13701 JP 59-204163 A JP-A-1-228950 JP-A-10-43595 JP-A-10-156185 US Pat. No. 5,688,739 Japanese Patent Laid-Open No. 52-140490 JP 2002-233768 A JP 2001-29788 A

  These methods are certainly effective when focusing on the fluidized state of the catalyst particles in the fluidized bed ammoxidation process. However, it is necessary to separate the catalyst particles outside the desired particle size range generated during catalyst production, particularly the catalyst particles having a particle size of less than 20 μm, and the step of reusing the separated catalyst particles. Therefore, improvement of the production cost is demanded from the viewpoint of an increase in catalyst production cost due to a deterioration in yield and an increase in the number of processes.

  The present invention has been made to solve the above-mentioned problems, and a composite oxide catalyst used in a fluidized bed ammoxidation process used for acrylonitrile production or the like is preferably used for a fluidized bed ammoxidation process. An object of the present invention is to provide a method for producing a composite oxide catalyst for a fluidized bed ammoxidation process that can be produced by reducing the content of particles having a diameter distribution, particularly less than 20 μm, and that is economically advantageous. .

First, when the particle size distribution of particles obtained by spray-drying a slurry containing all the raw materials of the catalyst component is measured by a laser diffraction method, the present inventors have a large apex in the range of 40 to 100 μm. In addition to the particle size distribution peak, attention was paid to the presence of a small particle size distribution peak having a peak in the range of less than 20 μm. Theoretically, the appearance of the latter peak is unnatural, so that the droplets are identified by the history (contact, collision, etc.) of the slurry droplets sprayed from the spray port in the spray drying process. It was considered that the latter peak was developed and the latter peak appeared. As a result of further investigation based on this consideration, among various conditions used for spray drying, the spray discharge speed when spraying the slurry into the spray dryer drying chamber, and the effectiveness in the spray dryer drying chamber The present inventors have found that the above problem can be solved by adjusting the air volume per 1 m ^{2 of the} cross-sectional area within a specific range, and have reached the present invention.
That is, the present invention is a method for producing a composite oxide catalyst used in a fluidized bed ammoxidation process, comprising a step of spray drying a slurry containing all raw materials of a catalyst component, and the slurry is spray dried. A flow characterized by having a spray discharge speed of 50 to 110 m / s for spraying and discharging into the dryer drying chamber, and an air volume per 1 m ² of effective sectional area in the spray dryer drying chamber of 400 to 600 m ³ / h. It is a manufacturing method of the composite oxide catalyst for a layer ammoxidation process.

According to the production method of the present invention, the ratio of the composite oxide catalyst having a preferable particle size distribution for the fluidized bed ammoxidation process, that is, the particle having a particle size of 20 to 120 μm is 85% by mass or more, and 20 to 44 μm. A composite oxide catalyst in which the proportion of particles having a particle size of 25 to 40% by mass and the proportion of particles having a particle size of less than 20 μm is 5% by mass or less can be easily produced.
Therefore, it is not necessary to perform a particle size adjustment operation again by classification or the like, and a stable operation with little catalyst loss can be realized in an industrial fluidized bed reactor.

Hereinafter, the present invention will be described in more detail.
The present invention is a method for producing a composite oxide catalyst used in a fluidized bed ammoxidation process, comprising a step of spray drying a slurry containing all raw materials of the catalyst component, and the slurry is spray dryer dried The spray discharge speed for spraying and discharging into the room is 50 to 110 m / s, and the air volume per 1 m ² of the effective sectional area in the spray dryer drying chamber is 400 to 600 m ³ / h. If any of the factors is missing, the object of the present invention cannot be achieved.
The mechanism of the effect of the present invention is not yet clear, but in the spray drying process, out of the slurry droplets sprayed from the spray port into the spray dryer drying chamber, such as contact or collision followed until drying. It is considered that the ratio of refinement due to the history is significantly reduced by adjusting the slurry spray discharge speed and the air volume per 1 m ² of the effective sectional area in the spray dryer drying chamber to a specific range. It is done.

The production method of the present invention can be performed, for example, as follows.
First, a slurry preparation step for preparing a slurry containing all the raw materials of the catalyst component is performed.
Here, the “catalyst component” means an element other than oxygen constituting the composite oxide catalyst, and the composite oxide catalyst for a fluidized bed ammoxidation process produced in the present invention has at least 2 as a catalyst component. It contains seed elements. It does not specifically limit as a catalyst component, It can select arbitrarily from the elements contained in the catalyst for conventional fluidized bed ammoxidation processes.

The raw material of the catalyst component used for the preparation of the slurry is not particularly limited, and the composite oxide catalyst for the fluidized bed ammoxidation process to be manufactured from the raw materials generally used for the manufacture of the composite oxide catalyst. What is necessary is just to select suitably according to a composition.
Examples of the raw material for the catalyst component include an oxide of the catalyst component, and a compound that can be converted into an oxide by igniting, and as the compound, chloride, sulfate, nitrate, ammonium salt of the catalyst component, Examples thereof include carbonates, hydroxides, organic acid salts, oxyacids, oxyacid salts, heteropolyacids, heteropolyacid salts, and mixtures thereof.

  In the present invention, the composite oxide catalyst for a fluidized bed ammoxidation process has a composition containing at least molybdenum, bismuth, iron and silicon as a catalyst component, or a composition containing at least antimony, iron and silicon. In particular, it is preferable to have a composition represented by either of the following general formulas (1) or (2).

_{Mo 12 Bi a Fe b A c} B d O e (SiO 2) f (1)
(Wherein, A represents at least one element selected from the group consisting of sodium, potassium, rubidium, cesium and thallium; B represents cobalt, nickel, copper, zinc, magnesium, calcium, strontium, barium, titanium, vanadium) , Chromium, manganese, tungsten, silver, aluminum, phosphorus, boron, tin, lead, gallium, germanium, arsenic, antimony, niobium, tantalum, zirconium, indium, sulfur, selenium, tellurium, lanthanum, cerium, praseodymium, neodymium, samarium Represents at least one element selected from the group consisting of europium, gadolinium, terbium, holmium, erbium, thulium and ytterbium; a, b, c, d, e and f represent the atomic ratio of each element; 0.1 5, b is 0.1 to 10, c is 0.01 to 3, d is 0 to 20, f is within the range of 10 to 200, and e is necessary to satisfy the valence of each component. (The atomic ratio of oxygen.)
_{Fe 10 Sb g Te h C k} D m E n O x (SiO 2) y (2)
(Wherein C represents at least one element selected from the group consisting of vanadium, molybdenum, and tungsten; D represents magnesium, calcium, strontium, barium, titanium, zirconium, niobium, chromium, manganese, cobalt, nickel, copper Represents at least one element selected from the group consisting of silver, zinc, boron, aluminum, gallium, indium, thallium, germanium, tin, lead, phosphorus, arsenic, and bismuth; E represents lithium, sodium, potassium, rubidium, And at least one element selected from the group consisting of cesium; g, h, k, m, n, x and y represent the atomic ratio of each element, g is 3 to 100, and h is 0.1 to 12 , K is 0.1 to 15, m is 0 to 50, n is 0 to 5, and y is within the range of 10 to 200. Ri, x is an atomic ratio of oxygen required to satisfy the valence of each component.)

A composite oxide catalyst having a composition represented by the general formula (1) is a composite containing molybdenum, bismuth, iron, at least one element represented by A, and silicon as an essential catalyst component in the form of silica. It may be an oxide and optionally contain at least one element represented by B.
In formula (1), as A, potassium, rubidium and cesium are preferable.
B is preferably cobalt, nickel, zinc, magnesium, vanadium, chromium, manganese, zirconium, tellurium, lanthanum, cerium, praseodymium, neodymium and samarium.
When A contains two or more elements, c represents the total atomic ratio of each element.
When B contains two or more elements, d represents the sum of the atomic ratios of the elements.

A composite oxide catalyst having a composition represented by the general formula (2) is a composite containing iron, antimony, tellurium, at least one element represented by C, and silicon as an essential catalyst component in the form of silica. The oxide may optionally contain at least one element represented by D and / or at least one element represented by E.
In the formula (2), as D, magnesium, niobium, chromium, manganese, cobalt, nickel, copper, zinc, boron and phosphorus are preferable.
When C contains two or more elements, k represents the total atomic ratio of each element.
When D contains two or more elements, m represents the total atomic ratio of each element.
When E contains two or more elements, n represents the total atomic ratio of each element.

For example, molybdenum raw materials include oxides such as molybdenum trioxide, molybdenum acids such as molybdic acid, ammonium paramolybdate, and ammonium metamolybdate or salts thereof, heteropolyacids containing molybdenum such as phosphomolybdic acid and silicomolybdic acid Alternatively, a salt thereof or the like can be used.
As the bismuth raw material, for example, bismuth salts such as bismuth nitrate, bismuth carbonate, bismuth sulfate, bismuth acetate, bismuth trioxide, metal bismuth and the like can be used. The raw material of bismuth can be used as a solid or as an aqueous solution, an aqueous nitric acid solution, or a slurry of a bismuth compound generated from these aqueous solutions, but it is preferable to use nitrate, a solution thereof, or a slurry generated from the solution.
Examples of the iron raw material include ferrous oxide, ferric oxide, ferrous nitrate, ferric nitrate, iron sulfate, iron chloride, iron organic acid salt, and iron hydroxide. May be used by dissolving in heated nitric acid. When using a solution containing an iron raw material, the pH of the solution may be adjusted with aqueous ammonia or the like.
Examples of the silicon raw material include silica (SiO ₂ ), and colloidal silica is preferably used. As colloidal silica, it can select from a commercially available thing suitably and can be used. The colloidal silica preferably has a colloidal particle size of 5 to 80 nm, more preferably 10 to 40 nm. Moreover, the silica content in colloidal silica is not particularly limited, and is preferably 10 to 50% by mass. Further, a mixture of a plurality of colloidal silicas having different colloidal particle diameters and / or silica contents may be used.

The slurry can be prepared by any known method from all raw materials of these catalyst components.
The solid content concentration of the slurry is 10 to 40% by mass, preferably 15 to 30% by mass. The solid content concentration of the slurry referred to here refers to the ratio of “mass in which the component constituting the slurry is converted to a stable oxide as the final form of the catalyst” with respect to “mass of the entire slurry”.
In the present invention, the pH of the slurry may be adjusted as necessary. Moreover, you may heat-process for aging, concentration, etc. in the range of 70-105 degreeC with respect to a slurry as needed.

Next, the spray drying process which dries the obtained slurry with a spray dryer is performed.
As a method for drying the slurry, a spray dryer generally used for spray drying can be used. For example, a rotary disk type spray dryer, a nozzle type spray dryer, or the like can be used. In particular, it is preferable to use a rotary disk type spray dryer.

In FIG. 1, the schematic block diagram of an example of a spray dryer is shown. The spray dryer 10 includes a spray dryer dryer chamber (hereinafter also referred to as a drying chamber) 11 and an atomizer (a disk of a rotary disk spray dryer, a nozzle spray) that sprays slurry into the dryer chamber 11. A nozzle of the dryer, etc.) 12 and a heater 13 for heating the gaseous fluid. The drying chamber 11 has an inlet 21 through which a gaseous fluid is supplied and an outlet 22 through which a gaseous fluid and a dried product are discharged at the bottom. Pipes 31, 32 and 33 for supplying a gaseous fluid to the heater 13 are joined to the heater 13, and the gaseous fluid heated by the heater 13 is fed into the drying chamber 11 into the inlet 21. A pipe 34 is joined, and a pipe 35 for discharging the gaseous fluid and the dried matter in the drying chamber 11 is joined to the outlet 22.
A pipe 36 for supplying slurry to the atomizer 12 is joined to the atomizer 12, and a slurry supply valve 37 and a liquid feed pump 38 are provided in the pipe 36.
The pipe 31 is provided with an air flow meter 41, the pipe 32 is provided with an air flow meter 42, the pipe 33 is provided with an air flow meter or a flow meter 43, and the pipe 34 is provided with a gas supply valve 44 and a spray dryer. A drying chamber inlet thermometer 45 is provided, and a spray dryer drying chamber outlet thermometer 46 is provided in the pipe 35.

In the present invention, at the time of spray drying, the spray discharge speed for spraying and discharging the slurry into the spray dryer drying chamber is set to 50 to 110 m / s, and the air volume per 1 m ² of the effective sectional area in the spray dryer drying chamber is set to 400. It is necessary to set it to -600m < ³ > / h. When the spray discharge speed of the slurry is less than 50 m / s, or when the air volume per 1 m ² of the effective sectional area in the spray dryer drying chamber is more than 600 m ³ / h, the number of particles having a particle size of less than 20 μm is small. The number of particles having a particle size of 20 to 44 μm is reduced, and in order to increase the number of particles having a particle size of 20 to 44 μm for industrial use, classification work is required, which is not preferable. When the spray discharge speed of the slurry is larger than 110 m / s, or when the air volume per 1 m ² of the effective sectional area in the spray dryer drying chamber is less than 400 m ³ / h, particles having a particle size of less than 20 μm are obtained. The number of particles having a particle size of less than 20 μm is required for industrial use, which is not preferable.
The lower limit of the spray discharge speed is preferably 60 m / s or more, and the upper limit is preferably 90 m / s or less.
The lower limit of the air volume per effective area of 1 m ^{2 in} the spray dryer drying chamber is preferably 440 m ³ / h, and the upper limit is preferably 560 m ³ / h or less.

The spray discharge speed here is a value calculated from the following formula (A) when the slurry is sprayed using a rotary disk spray dryer, and the slurry is sprayed using a nozzle spray dryer. The case is a value calculated by the following formula (B), and the unit is m / s.
Formula (A): Slurry spray discharge speed (m / s) = circularity × disk diameter (m) × {rotation speed (rpm) / 60}
Formula (B): Slurry spray discharge speed (m / s) = slurry supply speed (m ³ / s) / {circumference ratio × nozzle radius (m) × nozzle radius (m) × nozzle number}

In addition, the air volume per 1 m ² of the effective sectional area in the spray dryer drying chamber referred to here passes through the horizontal effective sectional area of 1 m ² in the drying chamber per hour under the inlet temperature of the drying chamber. The amount of gaseous fluid to be used, and the unit is m ³ / h.
The gaseous fluid mentioned here includes all gaseous fluids introduced into the spray dryer drying chamber. Specifically, all air such as heating air for drying, air for fuel combustion, air for atomizer cooling, and fuel combustion gas can be exemplified.
Furthermore, the spray dryer drying chamber inlet temperature mentioned here refers to the temperature measured at the joint portion of the piping for introducing the gaseous fluid into the drying chamber to the drying chamber. The temperature measurement point is preferably a joint portion between the pipe and the spray dryer drying chamber. However, if measurement at that portion is difficult, the pipe is connected from the joint portion between the pipe and the spray dryer drying chamber. What is necessary is just to measure in the location which touches the piping which exists in the range of 0-50 cm to the side.
When the gaseous fluid introduced into the spray dryer drying chamber is air such as heating air for drying or air for fuel combustion, the air volume is measured by separately measuring the air volume measured before heating. When the gaseous fluid introduced into the spray dryer drying chamber is a fuel combustion gas, it is calculated (X) by correcting the air flow at the inlet temperature of the dryer drying chamber, and in accordance with the form of the fuel before combustion. The air volume or flow rate of the fuel is measured, and the air volume calculated on the assumption that the fuel has completely combusted is calculated (Y) by correcting the temperature to the air volume at the spray dryer drying chamber inlet temperature measured separately. These values can be calculated (X + Y) by adding them.

  Spray drying can be performed by circulating a heated gaseous fluid in the spray dryer drying chamber, and the temperature of the gaseous fluid is 130 to 450 ° C. near the inlet to the drying chamber. Is preferable, and 140-400 degreeC is further more preferable. Furthermore, the temperature in the vicinity of the drying chamber outlet is preferably 100 to 250 ° C, more preferably 110 to 230 ° C.

In the present invention, a desired catalytically active structure is formed by calcining the dried product obtained in the step subsequent to the spray drying step at a temperature in the range of 450 to 1000 ° C. The firing temperature is more preferably 500 to 900 ° C.
Although there is no particular limitation on the firing time, it is preferable to perform firing for at least 1 hour or more because a catalyst having good activity can be obtained. The upper limit of the firing time is not particularly limited, but even if the treatment is performed for a longer time than necessary, the obtained effect is almost the same, so it is preferably within 20 hours.
There is no restriction | limiting in particular also about the method of baking, A general purpose baking furnace can be used. Industrially, a rotary kiln, a fluidized firing furnace or the like is preferably used.
In firing, the dried product may be baked by heating to 450 to 1000 ° C. as it is, but after performing one- or two-stage pre-baking at a temperature of about 250 to 450 ° C., 450 to 1000 is performed. A method of baking at 0 ° C. is more preferable.

By the production method of the present invention described above, a composite oxide catalyst having a particle size distribution satisfying the following requirements 1 to 3 can be produced.
(Requirement 1) The ratio of particles having a particle diameter of 20 to 120 μm is 85% by mass or more, and the ratio of particles having a particle diameter of 20 to 44 μm is 25 to 40% by mass.
(Requirement 2) The proportion of particles having a particle size of less than 20 μm is 5% by mass or less.
(Requirement 3) The ratio of particles having a particle size exceeding 120 μm is 10% by mass or less.
That is, in general, when the composite oxide catalyst is industrially used for a fluidized bed ammoxidation process, the size of the catalyst particles is 85% by mass or more of particles having a particle size of 20 to 120 μm, It is important that the proportion of particles having a particle size of 20 to 44 μm is 25 to 40%.
And since the particle | grains which have a particle size of less than 20 micrometers are small in mass, they are easily accompanied by reaction gas during reaction, and are scattered outside a reactor, so-called catalyst loss is caused. In order to reduce the reaction rate (conversion rate), the proportion of particles having a particle size of less than 20 μm is preferably as small as possible, and more preferably 5% by mass or less, and even more preferably 3% by mass or less.
Moreover, since the particle | grains which have a particle size exceeding 120 micrometers are large in mass, it is hard to fluidize well in a fluidized bed reactor. Therefore, if the ratio of particles having a particle size exceeding 120 μm is too large, the fluidized state is deteriorated, which leads to a decrease in the yield of the target product such as acrylonitrile. Therefore, the proportion of particles having a particle size exceeding 120 μm is preferably as small as possible, more preferably 10% by mass or less, and even more preferably 5% by mass or less.
Furthermore, in order to achieve a good fluidized state while suppressing catalyst loss, particles having a particle size of 20 to 120 μm are effective, and among these, the proportion of particles having a particle size of 20 to 44 μm is particularly high. It is important, and this ratio is more preferably 25 to 40% by mass, and further preferably 28 to 38% by mass.
A composite oxide catalyst satisfying these requirements 1 to 3 can be suitably used for a fluidized bed ammoxidation process.
Specific examples of ammoxidation include synthesis of acrylonitrile from propylene, synthesis of methacrylonitrile from isobutene and tertiary butanol, synthesis of benzonitrile from toluene, synthesis of hydrocyanic acid from methanol, and the like.

The fluidized bed ammoxidation process using the composite oxide catalyst for fluidized bed ammoxidation process produced by the production method of the present invention can be performed using a fluidized bed reactor.
Specifically, for example, when acrylonitrile is synthesized by vapor-phase catalytic ammoxidation of propylene with molecular oxygen and ammonia, a fluidized bed reactor is filled with a composite oxide catalyst, and propylene is supplied with a source gas containing oxygen and ammonia. It can carry out by supplying in a fluidized bed reactor and making it gas-solid contact.
The concentration of propylene in the raw material gas can be varied within a wide range, 1 to 20% by volume is appropriate, and 3 to 15% by volume is particularly preferable.
It is industrially advantageous to use air as an oxygen source when performing vapor phase ammoxidation, but if necessary, air enriched with pure oxygen can also be used.
The molar ratio of propylene to oxygen in the raw material gas is preferably 1: 1.5 to 1: 3, and the molar ratio of propylene to ammonia is preferably 1: 1 to 1: 1.5.
The source gas can be diluted with an inert gas, water vapor or the like.
The reaction pressure for carrying out the gas phase catalytic ammoxidation can be from normal pressure to several atmospheres. The reaction temperature is preferably in the range of 400 to 500 ° C.

Hereinafter, the present invention will be described in more detail with reference to examples. However, the present invention is not limited to this range as long as the gist of the present patent is not exceeded.
A representative sample of the composite oxide catalyst (hereinafter sometimes simply referred to as catalyst) produced in the following Examples and Comparative Examples was collected using a two-divider. The particle size distribution of the catalyst was measured using a laser diffraction particle size distribution measuring device.
Here, the measurement location of the spray dryer drying chamber inlet temperature was a location in contact with the piping 10 cm from the joint between the piping and the spray dryer drying chamber to the piping side.

[Example 1]
In a mixed solution of 4956.7 parts by mass of colloidal silica having a silica content of 30% by mass and 3000 parts by mass of pure water, 1248.3 parts by mass of ammonium paramolybdate was dissolved (solution A).
Separately, to 1300 parts by mass of a 17% by mass nitric acid aqueous solution, 476.1 parts by mass of iron (III) nitrate, 685.2 parts by mass of nickel nitrate, 226.6 parts by mass of magnesium nitrate, 171.4 parts by mass of cobalt nitrate, 94% of chromium nitrate .3 parts by mass, 127.9 parts by mass of cerium nitrate, 142.9 parts by mass of bismuth nitrate, 5.2 parts by mass of rubidium nitrate, and 4.2 parts by mass of potassium nitrate were dissolved (Liquid B).
While the liquid A was well stirred, the liquid B was mixed there to obtain an aqueous slurry. The solid content concentration of the aqueous slurry at this time was 24.1% by mass.
Using the rotary disk type spray dryer, the obtained aqueous slurry was subjected to a disk diameter of 120 mmφ, a rotational speed of 14,000 rpm, an inlet temperature of 250 ° C., and an air flow rate of 495 m ³ / h per 1 m ^{2 of} an effective sectional area in the spray dryer drying chamber. The dried powder was obtained by spray drying under the following conditions.
The spray discharge speed of the slurry at this time was calculated as 88 m / s from the following calculation formula.
[Calculation Formula] Slurry spray discharge speed (m / s) = circularity × disk diameter (m) × {rotation speed (rpm) / 60}
The obtained dried powder was calcined at 250 ° C. for 2 hours and then at 450 ° C. for 3 hours, and then calcined at 590 ° C. for 5 hours to obtain Catalyst 1.
The composition of the obtained catalyst 1 is calculated from the raw material charge as follows.
Mo ₁₂ Bi _0.5 Fe ₂ Ce _0.5 Cr _0.4 Ni ₄ Mg _1.5 Co ₁ K _0.07 Rb _0.06 O _e (SiO ₂ ) ₄₂
(Here, e is the atomic ratio of oxygen necessary to satisfy the valence of each of the other elements in the composition.)
As a result of examining the particle size distribution of the catalyst 1, the proportion of particles having a particle size of less than 20 μm was 1.6% by mass, and the proportion of particles having a particle size of 20 to 44 μm was 36.0% by mass, 20 to 20%. The proportion of particles having a particle size of 120 μm was 97.4% by mass.

[Example 2]
The aqueous slurry obtained by preparing in the same manner as in Example 1, using a rotary disk spray dryer, has a disk diameter of 120 mmφ, a rotational speed of 12,000 rpm, an inlet temperature of 230 ° C., and an effective cross-sectional area in the spray dryer drying chamber. Spray drying was carried out under the condition of an air volume per 1 m ² of 442 m ³ / h to obtain a dry powder. The spray discharge speed of the slurry at this time was calculated as 75 m / s by the calculation formula shown in Example 1.
The obtained dried powder was calcined at 250 ° C. for 2 hours and then at 450 ° C. for 3 hours, and then calcined at 590 ° C. for 5 hours to obtain Catalyst 2.
As a result of examining the particle size distribution of the catalyst 2, the proportion of particles having a particle size of 20 μm or less was 1.9% by mass, and the proportion of particles having a particle size of 20 to 44 μm was 34.4% by mass, 20 to 120 μm. The proportion of particles having a particle size was 97.0% by mass.

[Example 3]
The aqueous slurry obtained by preparing in the same manner as in Example 1, using a rotary disk spray dryer, has a disk diameter of 120 mmφ, a rotational speed of 15,000 rpm, an inlet temperature of 300 ° C., and an effective cross-sectional area in the spray dryer drying chamber. Spray drying was performed under the condition of an air volume of 552 m ³ / h per 1 m ² to obtain a dry powder. The spray discharge speed of the slurry at this time was calculated as 94 m / s by the calculation formula shown in Example 1.
The obtained dried powder was calcined at 250 ° C. for 2 hours and then at 450 ° C. for 3 hours, and then calcined at 590 ° C. for 5 hours to obtain Catalyst 3.
As a result of examining the particle size distribution of the catalyst 3, the proportion of particles having a particle size of less than 20 μm was 2.5 mass%, and the proportion of particles having a particle size of 20 to 44 μm was 39.8 mass%, 20 to 120 μm. The proportion of particles having a particle size was 97.5% by mass.

[Example 4]
The aqueous slurry obtained by preparing in the same manner as in Example 1, using a rotary disk spray dryer, has a disk diameter of 120 mmφ, a rotation speed of 10,000 rpm, an inlet temperature of 300 ° C., and an effective cross-sectional area in the spray dryer drying chamber. Spray drying was performed under the condition of an air volume of 586 m ³ / h per 1 m ² to obtain a dry powder. The spray discharge speed of the slurry at this time was calculated as 63 m / s by the calculation formula shown in Example 1.
The obtained dried powder was calcined at 250 ° C. for 2 hours and then at 450 ° C. for 3 hours, and then calcined at 590 ° C. for 5 hours to obtain Catalyst 4.
As a result of examining the particle size distribution of the catalyst 4, the proportion of particles having a particle size of less than 20 μm was 0.8% by mass, and the proportion of particles having a particle size of 20 to 44 μm was 27.9% by mass, 20 to 120 μm. The proportion of particles having a particle size was 97.7% by mass.

[Example 5]
The aqueous slurry obtained by preparing in the same manner as in Example 1, using a rotary disk spray dryer, has a disk diameter of 120 mmφ, a rotation speed of 9,000 rpm, an inlet temperature of 270 ° C., and an effective cross-sectional area in the spray dryer drying chamber. Spray drying was performed under the condition of an air volume of 420 m ³ / h per 1 m ² to obtain a dry powder. The spray discharge speed of the slurry at this time was calculated as 57 m / s by the calculation formula shown in Example 1.
The obtained dried powder was calcined at 250 ° C. for 2 hours and then at 450 ° C. for 3 hours, and then calcined at 590 ° C. for 5 hours to obtain Catalyst 5.
As a result of examining the particle size distribution of the catalyst 5, the proportion of particles having a particle size of less than 20 μm is 3.6% by mass, the proportion of particles having a particle size of 20 to 44 μm is 29.9% by mass, and 20 to 120 μm. The proportion of particles having a particle size was 95.4% by mass.

[Example 6]
13.6 parts by mass of copper powder was dissolved in 761 parts by mass of 63% by mass nitric acid. After adding 740 parts by mass of pure water to this solution, the solution was heated to 60 ° C., and 59.8 parts by mass of electrolytic iron powder and 20.5 parts by mass of tellurium powder were added and dissolved little by little. After confirmation of dissolution, 3.3 parts by mass of boric acid and 62.3 parts by mass of cobalt nitrate were sequentially added and dissolved (solution C).
Separately, 14.0 parts by mass of ammonium paratungstate was dissolved in 680 parts by mass of pure water (Liquid D).
Separately, 22.7 parts by mass of ammonium paramolybdate and 20.5 parts by mass of tellurium powder were suspended in 130 parts by mass of pure water, heated to 80 ° C., and then 62 parts by mass of 35% by mass hydrogen peroxide solution was dropped. And dissolved (solution E).
While stirring, 1929.5 parts by mass of silica sol having a silica content of 20% by mass, 390.1 parts by mass of antimony trioxide powder, and D liquid were sequentially added to C liquid. 15 mass% ammonia water was dripped at this slurry, and pH was adjusted to 2.0. The slurry after pH adjustment was heat-treated at 99 ° C. for 3 hours under reflux. The slurry after the heat treatment was cooled to 80 ° C., and solution E was added. The solid content concentration of the aqueous slurry at this time was 18.2% by mass.
Using the rotary disk type spray dryer, the obtained aqueous slurry was subjected to a disk diameter of 100 mmφ, a rotational speed of 14,000 rpm, an inlet temperature of 300 ° C., and an air flow rate of 553 m ³ / h per 1 m ^{2 of} an effective sectional area in the spray dryer drying chamber. The dried powder was obtained by spray drying under the following conditions.
The spraying speed of the slurry at this time was calculated as 73 m / s from the following calculation formula.
[Calculation Formula] Slurry spray discharge speed (m / s) = circularity × disk diameter (m) × {rotation speed (rpm) / 60}
The obtained dried powder was calcined at 250 ° C. for 2 hours and then at 400 ° C. for 2 hours, and then fluidly calcined at 700 ° C. for 3 hours to obtain Catalyst 6.
The composition of the obtained catalyst 6 is calculated from the raw material charge as follows.
Fe ₁₀ Sb ₂₅ Te ₃ W _0.5 Mo _1.2 Co ₂ Cu ₂ B _0.5 O _x (SiO ₂ ) ₆₀
(Here, x is the atomic ratio of oxygen necessary to satisfy the valence of each of the other elements in the composition.)
As a result of examining the particle size distribution of the catalyst 6, the proportion of particles having a particle size of less than 20 μm is 1.2% by mass, and the proportion of particles having a particle size of 20 to 44 μm is 30.8% by mass, 20 to 120 μm. The ratio of particles having a particle size was 97.6% by mass.

[Example 7]
The aqueous slurry obtained in the same manner as in Example 6 was prepared using a rotary disk spray dryer, the disk diameter was 100 mmφ, the rotational speed was 16,000 rpm, the inlet temperature was 230 ° C., and the effective cross-sectional area in the spray dryer drying chamber. Spray drying was performed under the condition of an air volume of 448 m ³ / h per 1 m ² to obtain a dry powder. The spray discharge speed of the slurry at this time was calculated as 84 m / s by the calculation formula shown in Example 6.
The obtained dried powder was calcined at 250 ° C. for 2 hours and then at 400 ° C. for 3 hours, and then fluidly calcined at 700 ° C. for 3 hours to obtain Catalyst 7.
As a result of examining the particle size distribution of the catalyst 7, the proportion of particles having a particle size of less than 20 μm is 2.0 mass%, and the proportion of particles having a particle size of 20 to 44 μm is 37.8 mass%, 20 to 120 μm. The ratio of the particles having a particle size was 98.0% by mass.

[Example 8]
The aqueous slurry obtained in the same manner as in Example 6 was prepared using a rotary disk spray dryer, the disk diameter was 100 mmφ, the rotational speed was 18,000 rpm, the inlet temperature was 270 ° C., and the effective cross-sectional area in the spray dryer drying chamber. The dried powder 8 was obtained by spray-drying under conditions of an air volume of 490 m ³ / h per 1 m ² . The spray discharge speed of the slurry at this time was calculated as 94 m / s by the calculation formula shown in Example 6.
The obtained dried powder was calcined at 250 ° C. for 2 hours and then at 400 ° C. for 3 hours, and then fluidly calcined at 700 ° C. for 3 hours to obtain Catalyst 8.
As a result of examining the particle size distribution of the catalyst 8, the proportion of particles having a particle size of less than 20 μm was 2.8% by mass, and the proportion of particles having a particle size of 20 to 44 μm was 39.5% by mass, 20 to 120 μm. The proportion of particles having a particle size was 97.2% by mass.

[Example 9]
The aqueous slurry obtained in the same manner as in Example 6 was prepared using a rotary disk spray dryer, the disk diameter was 100 mmφ, the rotational speed was 12,000 rpm, the inlet temperature was 250 ° C., and the effective cross-sectional area in the spray dryer drying chamber. Spray drying was performed under the condition of an air volume of 414 m ³ / h per 1 m ² to obtain a dry powder. The spray discharge speed of the slurry at this time was calculated to be 63 m / s by the calculation formula shown in Example 6.
The obtained dried powder was calcined at 250 ° C. for 2 hours and then at 400 ° C. for 3 hours, and then fluidly calcined at 700 ° C. for 3 hours to obtain Catalyst 9.
As a result of examining the particle size distribution of the catalyst 9, the proportion of particles having a particle size of less than 20 μm is 3.1% by mass, and the proportion of particles having a particle size of 20 to 44 μm is 31.2% by mass, 20 to 120 μm. The proportion of particles having a particle size was 96.3% by mass.

[Example 10]
The aqueous slurry obtained in the same manner as in Example 6 was prepared using a rotary disk spray dryer, the disk diameter was 100 mmφ, the rotation speed was 10,000 rpm, the inlet temperature was 350 ° C., and the effective sectional area in the spray dryer drying chamber. Spray drying was performed under conditions of an air volume of 577 m ³ / h per 1 m ² to obtain a dry powder. The spray discharge speed of the slurry at this time was calculated as 52 m / s by the calculation formula shown in Example 6.
The obtained dried powder was calcined at 250 ° C. for 2 hours and then at 400 ° C. for 3 hours, and then fluidly calcined at 700 ° C. for 3 hours to obtain catalyst 10.
As a result of examining the particle size distribution of the catalyst 10, the proportion of particles having a particle size of less than 20 μm is 1.2% by mass, and the proportion of particles having a particle size of 20 to 44 μm is 25.9% by mass, 20 to 120 μm. The proportion of particles having a particle size was 96.9% by mass.

[Comparative Example 1]
The aqueous slurry obtained by preparing in the same manner as in Example 1 was measured using a rotary disk spray dryer, the disk diameter was 120 mmφ, the rotational speed was 14,000 rpm, the inlet temperature was 230 ° C., and the effective cross-sectional area in the spray dryer drying chamber. Spray drying was performed under the condition of an air volume per 1 m ² of 383 m ³ / h to obtain a dry powder. The spray discharge speed of the slurry at this time was calculated as 88 m / s by the calculation formula shown in Example 1.
The obtained dried powder was calcined at 250 ° C. for 2 hours and then at 450 ° C. for 3 hours, and then calcined at 590 ° C. for 5 hours to obtain Catalyst A.
As a result of examining the particle size distribution of the catalyst A, the proportion of particles having a particle size of less than 20 μm was 7.7% by mass, and the proportion of particles having a particle size of 20 to 44 μm was 35.6% by mass, 20 to 120 μm. The proportion of particles having a particle size was 92.3% by mass.

[Comparative Example 2]
The aqueous slurry obtained by preparing in the same manner as in Example 1, using a rotary disk spray dryer, has a disk diameter of 120 mmφ, a rotational speed of 7,000 rpm, an inlet temperature of 270 ° C., and an effective cross-sectional area in the spray dryer drying chamber. Spray drying was performed under the condition of an air volume of 453 m ³ / h per 1 m ² to obtain a dry powder. The spray discharge speed of the slurry at this time was calculated to be 44 m / s by the calculation formula shown in Example 1.
The obtained dried powder was calcined at 250 ° C. for 2 hours and then at 450 ° C. for 3 hours, and then calcined at 590 ° C. for 5 hours to obtain Catalyst B.
As a result of examining the particle size distribution of the catalyst B, the proportion of particles having a particle size of less than 20 μm is 2.6% by mass, and the proportion of particles having a particle size of 20 to 44 μm is 20.3% by mass, 20 to 120 μm. The proportion of particles having a particle size was 92.8% by mass.

[Comparative Example 3]
The aqueous slurry obtained by preparing in the same manner as in Example 1, using a rotary disk spray dryer, has a disk diameter of 120 mmφ, a rotational speed of 18,000 rpm, an inlet temperature of 250 ° C., and an effective cross-sectional area in the spray dryer drying chamber. Spray drying was performed under the condition of an air volume per 1 m ² of 464 m ³ / h to obtain a dry powder. The spray discharge speed of the slurry at this time was calculated as 113 m / s by the calculation formula shown in Example 1.
The obtained dried powder was calcined at 250 ° C. for 2 hours and then at 450 ° C. for 3 hours, and then calcined at 590 ° C. for 5 hours to obtain Catalyst C.
As a result of examining the particle size distribution of the catalyst C, the proportion of particles having a particle size of less than 20 μm was 5.6% by mass, and the proportion of particles having a particle size of 20 to 44 μm was 51.5% by mass, 20 to 120 μm. The proportion of particles having a particle size was 94.4% by mass.

[Comparative Example 4]
The aqueous slurry obtained in the same manner as in Example 6 was prepared using a rotary disk spray dryer, disk diameter 100 mmφ, rotation speed 10,000 rpm, inlet temperature 250 ° C., effective cross-sectional area in the spray dryer drying chamber. Spray drying was performed under the condition of an air volume of 608 m ³ / h per 1 m ² to obtain a dry powder. The spray discharge speed of the slurry at this time was calculated as 52 m / s by the calculation formula shown in Example 6.
The obtained dried powder was calcined at 250 ° C. for 2 hours and then at 400 ° C. for 2 hours, and then fluidly calcined at 700 ° C. for 3 hours to obtain Catalyst D.
As a result of examining the particle size distribution of the catalyst D, the proportion of particles having a particle size of less than 20 μm was 0.8 mass%, and the proportion of particles having a particle size of 20 to 44 μm was 23.6 mass%, 20 to 120 μm. The proportion of particles having a particle size was 96.3% by mass.

[Comparative Example 5]
The aqueous slurry obtained in the same manner as in Example 6 was prepared using a rotary disk spray dryer, the disk diameter was 100 mmφ, the rotation speed was 8,000 rpm, the inlet temperature was 320 ° C., and the effective sectional area in the spray dryer drying chamber. Spray drying was performed under the condition of an air volume of 639 m ³ / h per 1 m ² to obtain a dry powder. The spray discharge speed of the slurry at this time was calculated to be 42 m / s by the calculation formula shown in Example 6.
The obtained dried powder was calcined at 250 ° C. for 2 hours and then at 400 ° C. for 2 hours, and then fluidly calcined at 700 ° C. for 3 hours to obtain Catalyst E.
As a result of examining the particle size distribution of the catalyst E, the proportion of particles having a particle size of less than 20 μm is 0.0 mass%, and the proportion of particles having a particle size of 20 to 44 μm is 18.0 mass%, 20 to 120 μm. The ratio of the particles having a particle size was 93.0% by mass.

[Comparative Example 6]
The aqueous slurry obtained in the same manner as in Example 6 was prepared using a rotary disk spray dryer, the disk diameter was 100 mmφ, the rotational speed was 20,000 rpm, the inlet temperature was 250 ° C., and the effective cross-sectional area in the spray dryer drying chamber. Spray drying was performed under the condition of an air volume of 358 m ³ / h per 1 m ² to obtain a dry powder. The spray discharge speed of the slurry at this time was calculated to be 105 m / s by the calculation formula shown in Example 6.
The obtained dried powder was calcined at 250 ° C. for 2 hours and then at 400 ° C. for 2 hours, and then fluidly calcined at 700 ° C. for 3 hours to obtain Catalyst F.
As a result of examining the particle size distribution of the catalyst F, the proportion of particles having a particle size of less than 20 μm was 8.3 mass%, the proportion of particles having a particle size of 20 to 44 μm was 45.5 mass%, and 20 to 120 μm. The proportion of particles having a particle size was 91.7% by mass.

  The production conditions used in the above Examples and Comparative Examples and the particle size distribution of the obtained catalyst are shown in Table 1.

As is clear from the above results, Examples 1 to 10 in which the spray discharge speed was 50 to 110 m / s and the air volume per 1 m ² of the effective sectional area in the spray dryer drying chamber was 400 to 600 m ³ / h. The catalyst obtained in (1) had a particle size distribution satisfying the requirements 1 to 3 described above. Among them, Examples 1, 2, 4, 6, 7, and 9 in which the spray discharge speed is in the range of 60 to 90 m / s, and Examples 1 to ^{3 in which the} air volume is in the range of 440 to 560 m ³ / h. Nos. 6 to 8 have a good particle size distribution, and in Examples 1, 2, 6, and 7 that satisfy both of these conditions, the proportion of particles having a particle size of less than 20 μm is 3% by mass or less. In addition, the ratio of particles having a particle diameter of 20 to 44 μm was in the range of 28 to 38% by mass, which was excellent.
On the other hand, the catalyst obtained in Comparative Examples 1 to 6 that did not satisfy one or both of the spray discharge speed and the air volume range had a ratio of particles having a particle diameter of less than 20 μm exceeding 5% by mass, The proportion of particles having a particle size of 20 to 44 μm was out of the range of 25 to 40% by mass. For example, in Comparative Examples 1, 3, and 6 in which the air volume was small and the spray discharge speed was fast, the ratio of particles having a particle diameter of less than 20 μm was high. In Comparative Examples 2, 4 and 5 in which the air volume was large or the spray discharge speed was slow, the ratio of particles having a particle diameter of 20 to 44 μm was low.

It is a schematic block diagram which shows an example of a spray dryer.

Explanation of symbols

DESCRIPTION OF SYMBOLS 10 ... Spray dryer, 11 ... Drying chamber, 12 ... Atomizer, 13 ... Heater, 21 ... Inlet, 22 ... Outlet, 31 ... Pipe, 32 ... Pipe, 33 ... Pipe, 34 ... Pipe, 35 ... Pipe, 36 ... Piping, 37 ... Slurry supply valve, 38 ... Liquid feed pump, 41 ... Air flow meter, 42 ... Air flow meter, 43 ... Air flow meter, 44 ... Gas supply valve, 45 ... Spray dryer drying chamber inlet thermometer, 46 ... Spray drying Dryer outlet thermometer

Claims (1)

A method for producing a composite oxide catalyst used in a fluidized bed ammoxidation process, comprising:
Having a step of spray drying a slurry containing all raw materials of the catalyst component;
The spray discharge speed for spraying and discharging the slurry into the spray dryer drying chamber is 50 to 110 m / s, and the air volume per 1 m ² of the effective sectional area in the spray dryer drying chamber is 400 to 600 m ³ / h. A method for producing a composite oxide catalyst for a fluidized bed ammoxidation process characterized by the above.

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