JP5378041B2 - Method for producing composite oxide catalyst for acrylonitrile synthesis - Google Patents

Description

  The present invention relates to a method for producing a composite oxide catalyst for synthesizing acrylonitrile containing at least molybdenum, bismuth, iron and silica.

  As a method for synthesizing acrylonitrile, a so-called ammoxidation reaction method in which propylene, ammonia and oxygen are reacted in the presence of a fluidized bed catalyst is widely known. Many studies have been made on the fluidized bed catalyst used at that time, and various catalysts have been proposed so far.

For example, Patent Document 1 discloses an oxide catalyst containing molybdenum, bismuth and iron, and Patent Document 2 discloses an oxide catalyst containing iron and antimony.
Improvement of these catalysts has also been performed vigorously. For example, Patent Documents 3 to 8 disclose an improved catalyst in which other components are added in addition to molybdenum, bismuth and iron, and Patent Document 9 discloses iron, An improved catalyst in which other components are added in addition to antimony is disclosed.
Furthermore, efforts have been made to improve the yield of the target product acrylonitrile by improving the catalyst production method. For example, Patent Documents 10 to 18 disclose a method for adjusting the pH of a slurry containing a catalyst component to a predetermined range, a method for mixing specific elements after pH adjustment, a heat treatment, and a method for performing a concentration treatment, Patent Document 19 discloses a method of holding a slurry for a certain period of time under a specific condition during the process. Patent Document 20 discloses a method in which a catalyst or catalyst precursor prepared in advance is impregnated with a specific component and then fired.

Japanese Patent Publication No. 38-17967 Japanese Examined Patent Publication No. 38-19111 JP 48-49719 A JP 55-56839 A JP 54-95513 A JP 58-67349 A JP 7-47272 A JP-A-10-43595 JP-A-4-118051 Japanese Patent Laid-Open No. 1-265058 JP-A-2-59046 JP-A-2-214543 JP-A-2-251250 JP 2000-37631 A JP 2000-42414 A Japanese Patent Laid-Open No. 1-265067 JP 2002-306968 A JP 2002-306969 A JP 2006-55732 A JP 11-309374 A

However, although these catalysts in the prior art have some effect in increasing the yield of acrylonitrile, they are still not sufficient, and further improvements have been desired from an industrial standpoint.
This invention is made | formed in view of the said situation, and it aims at providing the manufacturing method of the composite oxide catalyst which can synthesize | combine acrylonitrile with a high yield.

The method for producing a composite oxide catalyst for synthesizing acrylonitrile of the present invention comprises a step of preparing an aqueous slurry comprising at least molybdenum, bismuth, iron, and silica, and comprising a liquid phase and a solid phase; In the method for producing a composite oxide catalyst for acrylonitrile synthesis, comprising a step of drying to obtain a dried product and a step of calcining the obtained dried product at a temperature in the range of 500 to 750 ° C. Among the precipitated particles having a particle diameter of 1 μm or more and less than 150 μm, the ratio of the precipitated particles having a particle diameter of 1 μm or more and less than 10 μm is 53 to 74 % by volume, and the ratio of the precipitated particles having a particle diameter of 10 μm or more and less than 150 μm is 26 to 47 It is characterized by volume%.

  ADVANTAGE OF THE INVENTION According to this invention, the complex oxide catalyst which can synthesize | combine acrylonitrile with a high yield can be manufactured.

Hereinafter, the present invention will be described in detail.
The method for producing a composite oxide catalyst for acrylonitrile synthesis of the present invention (hereinafter sometimes referred to as “the catalyst production method of the present invention”) includes at least molybdenum, bismuth, iron, and silica, and a liquid phase. A step of preparing an aqueous slurry composed of a solid phase (aqueous slurry preparation step), a step of drying the aqueous slurry to obtain a dried product (drying step), and a step of firing the obtained dried product (firing step). Among the precipitated particles having a particle diameter of 1 μm or more and less than 150 μm contained in the aqueous slurry, the proportion of the precipitated particles having a particle diameter of 1 μm or more and less than 10 μm is 30 to 90% by volume, and the particle diameter is 10 μm or more and 150 μm It is characterized in that the proportion of the precipitated particles of less than 10 to 70% by volume.

In the catalyst production method of the present invention, first, an aqueous slurry comprising a liquid phase and a solid phase is prepared by mixing raw materials of components constituting the catalyst such as molybdenum, bismuth, iron, silica and the like in an aqueous slurry preparation step. Next, the aqueous slurry obtained in the drying step is dried to obtain a dried product.
As a result of intensive studies, the present inventors have found that a catalyst capable of synthesizing acrylonitrile in a high yield can be obtained by controlling the particle diameter of the precipitated particles in the aqueous slurry to be subjected to the drying step within a specific range. The invention has been completed.

  That is, the lower limit of the ratio of the precipitated particles having a particle size of 1 μm or more and less than 10 μm among the precipitated particles having a particle size of 1 μm or more and less than 150 μm contained in the aqueous slurry to be subjected to the drying step is 30% by volume, preferably 35 The upper limit is 90% by volume, and preferably 85% by volume. Further, the lower limit of the ratio of precipitated particles having a particle diameter of 10 μm or more and less than 150 μm is 10% by volume, preferably 15% by volume, and the upper limit is 70% by volume, preferably 65% by volume.

  Among the precipitated particles having a particle diameter of 1 μm or more and less than 150 μm, the ratio of the precipitated particles having a particle diameter of 1 μm or more and less than 10 μm is less than the above lower limit, or the ratio of the precipitated particles having a particle diameter of 10 μm or more but less than 150 μm is larger than the above upper limit. In this case, the catalytic activity and the acrylonitrile yield are reduced. In addition, there may be a problem in physical properties such as a decrease in bulk density and particle strength of the obtained catalyst. Furthermore, when the number of particles having a large particle diameter is extremely large, problems such as sedimentation of precipitated particles in the liquid feeding line are likely to occur when the aqueous slurry is fed.

  Among the precipitated particles having a particle diameter of 1 μm or more and less than 150 μm, the ratio of the precipitated particles having a particle diameter of 1 μm or more and less than 10 μm is larger than the above upper limit, or the ratio of the precipitated particles having a particle diameter of 10 μm or more but less than 150 μm is less than the above lower limit. In this case, the acrylonitrile yield decreases. In particular, when the reaction is performed under a condition where the reaction pressure is increased, the decrease in the acrylonitrile yield becomes significant.

  If excessive precipitated particles having a particle size of 150 μm or more are present in the aqueous slurry subjected to the drying step, the acrylonitrile yield may be reduced, and the bulk density and particle strength of the resulting catalyst may be reduced. Further, when the aqueous slurry is fed, problems such as sedimentation of precipitated particles in the feeding line are likely to occur. Therefore, when there are excessive precipitated particles having a particle diameter of 150 μm or more, it is preferable to make them fine by pulverization or to be removed by filtration. The ratio of the precipitated particles having a particle size of 150 μm or more is preferably 5% by volume or less, more preferably 3% by volume or less with respect to the precipitated particles having a particle size of 1 μm or more and less than 150 μm.

  There is no particular limitation on the precipitated particles having a particle diameter of less than 1 μm. For example, when silica sol is used as the silica raw material, a large amount of precipitated particles having a particle diameter of less than 1 μm is contained. The amount of silica sol added may be appropriately adjusted in consideration of the activity of the resulting catalyst. . However, for active ingredients other than silica, if a large amount of precipitated particles having a particle size of less than 1 μm are contained, there may be problems such as a decrease in acrylonitrile yield and difficulty in controlling the activity.

  The particle diameter of the precipitated particles in the aqueous slurry can be measured by any known method. Examples of the measurement method include laser diffraction method, dynamic light scattering method, centrifugal sedimentation method, and electric detector method.

Examples of the method for controlling the particle size of the precipitated particles include the following methods.
For example, when a raw material is dispersed or dissolved to form a solution, and a precipitate is formed by mixing the solution, a method of setting the concentration, temperature, pH, or the like of the solution at the time of mixing to a specific range can be mentioned. When the raw material is used as a solid, a method of controlling the particle size of the solid raw material by pulverization or the like can be mentioned. In addition, the particle size of the precipitated particles can be changed by adjusting the stirring strength and time of the aqueous slurry.

  The particle size of the precipitated particles can also be controlled by aging the aqueous slurry or performing a heat treatment. In addition, a method of atomizing solid particles in the aqueous slurry using a homogenizer, a fine mill, or the like, or ultrasonically treating the aqueous slurry is also effective. However, if the atomization process is excessively performed, the proportion of precipitated particles having a particle diameter of 1 μm or more and less than 10 μm may be increased more than necessary. In addition, it is not preferable that the active ingredient other than silica has a large amount of precipitated particles having a particle diameter of less than 1 μm. Therefore, in order to prevent the precipitated particles from being excessively pulverized, it is preferable to perform the atomization treatment while appropriately measuring the particle diameter of the precipitated particles.

  In the aqueous slurry preparation step, the other requirements are not particularly limited as long as the requirements related to the particle size of the precipitated particles in the aqueous slurry are satisfied, and can be appropriately selected from known preparation methods. .

There is no restriction | limiting in particular about the raw material used for preparation of aqueous slurry, According to the preparation method, the property of the target catalyst, etc., it can select suitably.
For example, as a raw material of the molybdenum component, an oxide such as molybdenum trioxide, molybdic acid or a salt thereof such as ammonium molybdate, ammonium paramolybdate, or ammonium metamolybdate, molybdenum such as phosphomolybdic acid or silicomolybdic acid Heteropolyacid containing or a salt thereof can be used.

  As raw materials for the bismuth component, bismuth salts such as bismuth nitrate, bismuth carbonate, bismuth sulfate, bismuth acetate, bismuth trioxide, metal bismuth, and the like can be used. These raw materials can be used in the form of a solid or as an aqueous slurry of an aqueous solution, an aqueous nitric acid solution, or a bismuth compound generated from the aqueous solution, but it is preferable to use nitrate, a solution thereof, or an aqueous slurry generated from the solution.

  As raw materials for iron components, ferrous oxide, ferric oxide, ferrous nitrate, ferric nitrate, iron sulfate, iron chloride, iron organic acid salt, iron hydroxide, etc. can be used. Iron may be dissolved in heated nitric acid. The solution containing the iron component may be used after adjusting the pH with aqueous ammonia or the like. When adjusting the pH, it is possible to prevent the iron component from being precipitated by allowing a chelating agent to coexist in a solution containing the iron component. Examples of chelating agents that can be used here include ethylenediaminetetraacetic acid, lactic acid, citric acid, tartaric acid, and gluconic acid. When preparing an aqueous solution containing iron ions and a chelating agent, it is preferable to use these raw materials by dissolving them in an acid or water.

  As a raw material for the silica component, silica sol is preferable, which can be appropriately selected from commercially available ones.

  The composite oxide catalyst for acrylonitrile synthesis (hereinafter sometimes referred to as “composite oxide catalyst”) to be produced by the catalyst production method of the present invention contains catalyst components other than molybdenum, bismuth, iron and silica. In this case, the other raw materials include oxides of the catalyst components, or chlorides, sulfates, nitrates, ammonium salts, carbonates, hydroxides, organic acid salts, which can be converted into oxides when heated. Oxyacids, oxyacid salts, heteropolyacids, heteropolyacid salts, or mixtures thereof can be used.

These raw material compounds are mixed in a solid, solution, aqueous slurry or the like in an aqueous medium to obtain a desired aqueous slurry. Examples of the aqueous medium include water and nitric acid.
The aqueous slurry does not necessarily contain all the elements constituting the catalyst, and the raw materials of elements not contained in the aqueous slurry may be added in each step before the drying step. You may add by the method of impregnating a later catalyst.

Next, the aqueous slurry is dried in a drying step. Thereby, a dried product (catalyst precursor) is obtained.
There is no restriction | limiting in particular about the method of drying, It can select suitably from a well-known method and can use it.
The composite oxide catalyst produced by the catalyst production method of the present invention is preferably used as a fluidized bed catalyst. In that case, it is preferable 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.

During spray drying, the temperature of the hot air circulated in the drying chamber of the spray dryer is preferably 130 ° C., more preferably 140 ° C., and more preferably 350 ° C. near the inlet to the drying chamber. ° C, more preferably 320 ° C. The lower limit of the temperature in the vicinity of the drying chamber outlet is preferably 100 ° C., more preferably 110 ° C., and the upper limit is preferably 250 ° C., more preferably 230 ° C. 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 150 ° C, more preferably 30 to 120 ° C.
If each of the above temperatures is outside the predetermined range, problems such as reduction in the activity of the catalyst obtained and acrylonitrile yield, and reduction in bulk density and particle strength of the catalyst particles may occur. .

  Further, the particle size of the obtained catalyst is preferably in the range of 5 to 200 μm, and more preferably in the range of 10 to 180 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.

Next, in the calcination step, the dried product (catalyst precursor) is calcinated to obtain a composite oxide catalyst containing at least molybdenum, bismuth, iron and silica. The activity as a catalyst is expressed by the firing step.
In the present invention, the firing is preferably carried out in two or more times. The acrylonitrile yield may be improved by performing the firing in two or more steps.
If the last firing is final firing, and the firing performed prior to final firing is temporary firing, the lower limit of the final firing temperature is preferably 500 ° C, more preferably 520 ° C, and the upper limit is preferably 750 ° C, more preferably Is 730 ° C. When the final calcination temperature is lower than the lower limit, sufficient catalytic performance is not exhibited, and the acrylonitrile yield may be lowered. On the other hand, when it is higher than the upper limit, the acrylonitrile yield may be decreased, or the activity of the catalyst may be decreased. Moreover, ammonia combustibility increases remarkably and the ammonia basic unit may decrease, which is not preferable.

  The lower limit of the final firing time is preferably 0.1 hour, and more preferably 0.5 hour. When the calcination time is shorter than the lower limit, sufficient catalyst performance is not exhibited, and the acrylonitrile yield may be reduced. The upper limit is not particularly limited, but is usually within 20 hours because the effect obtained even if the time is extended more than necessary does not become a certain value or more.

On the other hand, the lower limit of the pre-baking temperature is preferably 160 ° C, more preferably 180 ° C, and the upper limit is preferably 480 ° C, more preferably 450 ° C. Moreover, it is preferable that the temperature of temporary baking shall be 50-200 degreeC lower than the temperature of final baking.
The lower limit of the calcination time is preferably 0.1 hour, more preferably 0.5 hour. When the calcination time is shorter than the lower limit, sufficient catalyst performance is not exhibited, and the acrylonitrile yield may be reduced. The upper limit is not particularly limited, but is usually within 20 hours because the effect obtained even if the time is extended more than necessary does not become a certain level.

A general-purpose firing furnace can be used for final firing and temporary firing. When the composite oxide catalyst produced by the method for producing a catalyst of the present invention is a fluidized bed catalyst, a rotary kiln, a fluidized firing furnace or the like is particularly preferably used.
The gas atmosphere used in the final firing and the preliminary firing may be an oxidizing gas atmosphere containing oxygen or an inert gas atmosphere such as nitrogen, but it is convenient to use air.

The composite oxide catalyst produced by the catalyst production method according to the present invention preferably has a composition represented by the following general formula (I).
_{Mo a Bi b Fe c A d} B e C f D g O h (SiO 2) i ··· (I)

In the general formula (I), Mo, Bi, Fe, and O represent molybdenum, bismuth, iron, and oxygen, respectively, and A is at least one selected from the group consisting of sodium, potassium, rubidium, cesium, and thallium. Element, B is at least one element selected from the group consisting of cobalt, nickel, copper, zinc, magnesium, calcium, barium and manganese, C is chromium, vanadium, tungsten, niobium, zirconium, lanthanum, cerium, praseodymium, At least one element selected from the group consisting of neodymium and samarium, D is at least one element selected from the group consisting of thallium, silver, boron, aluminum, indium, antimony, phosphorus and tellurium, and SiO ₂ is silica Represents.
The symbols a, b, c, d, e, f, g, h and i represent atomic ratios. When a = 12, the lower limit of b is preferably 0.1, more preferably 0.2, and the upper limit. Is preferably 5, more preferably 4.5. The lower limit of c is preferably 0.1, more preferably 0.3, and the upper limit is preferably 10, more preferably 8. The lower limit of d is preferably 0.01, more preferably 0.03, and the upper limit is preferably 3, more preferably 2.5. The lower limit of e is preferably 2, more preferably 2.5, and the upper limit is preferably 12, more preferably 10. The lower limit of f is preferably 0.5, more preferably 0.6, and the upper limit is preferably 5, more preferably 4. The lower limit of g is 0, and the upper limit is preferably 5, more preferably 4. The lower limit of i is preferably 20, more preferably 25, and the upper limit is preferably 200, more preferably 180. h is the number of oxygen atoms necessary to satisfy the valence of each component.

  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.

When the composition of the composite oxide catalyst produced by the method for producing a catalyst according to the present invention is outside the range of the general formula (I), the acrylonitrile yield is lowered or the properties of the obtained catalyst are not preferred. For example, the effects of the present invention may not be sufficiently exhibited.
In order to make the catalyst composition within the range of the general formula (I), for example, the addition amount of each raw material in the aqueous slurry preparation step and the addition amount of raw material added in each step from the aqueous slurry preparation step to drying May be appropriately selected. In addition, when the catalyst is produced by a method such as impregnating the dried catalyst, the amount of raw material added by impregnation or the like may be appropriately selected.

  According to the catalyst production method of the present invention, a composite oxide capable of synthesizing acrylonitrile in high yield in acrylonitrile synthesis by propylene ammoxidation reaction by controlling the particle size of the precipitated particles in the aqueous slurry to a specific range. A catalyst is obtained.

  In order to synthesize acrylonitrile by the ammoxidation reaction of propylene using the composite oxide catalyst produced by the catalyst production method of the present invention, it is preferable to use a fluidized bed reactor. It can be carried out by filling a fluidized bed reactor with a composite oxide catalyst and supplying a raw material gas containing propylene, ammonia and oxygen to the catalyst bed.

Although it does not specifically limit as source gas, The source gas of the range whose propylene / 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 measurement of the particle diameter of the precipitated particles in the aqueous slurry and the activity test of the catalyst obtained in each example were performed according to the following procedure.

[Measurement of particle size]
An aqueous slurry is dispersed in an aqueous medium at a predetermined concentration, and measured using a laser diffraction particle size distribution measuring device (LS13320 manufactured by Beckman Coulter, Inc.) after being circulated for about 1 minute to obtain a volume-based particle size distribution. It was. The particle diameter was calculated from the measured particle size distribution. The measurement conditions are shown below.
・ Pump speed: 70,
・ Dispersion medium: water,
-Dispersion medium refractive index: 1.333,
・ Optical model used: Garnet,
PIDS (Polarization Intensity Differential Scattering) relative concentration: 40-60%.

[Catalyst activity test]
A catalyst is packed in a fluidized bed reactor having an inner diameter of 25 mm and a height of 40 mm in the catalyst fluidized portion, and the composition is propylene / ammonia / oxygen (supplied as air) / water vapor = 1/1 in the fluidized bed reactor. A mixed gas of 1 / 2.2 / 0.5 (molar ratio) is fed at a gas linear velocity of 4.5 cm / sec (sec.), Under reaction conditions of a reaction temperature of 440 ° C. and a reaction pressure of 200 kPa, Acrylonitrile was synthesized by ammoxidation of propylene.

In this synthesis reaction, the contact time between the raw material gas and the catalyst particles, the propylene conversion rate, and the acrylonitrile yield are defined by the following equations. Each carbon mass in the following formula was analyzed by gas chromatography.
Contact time (sec.) = Apparent volume density-based catalyst volume (mL) / feed gas amount converted to reaction conditions (mL / sec.)
Propylene conversion rate (%) = (carbon mass of supplied propylene−carbon mass of unreacted propylene) / carbon mass of supplied propylene Acrylonitrile yield (%) = (carbon mass of produced acrylonitrile / carbon of supplied propylene) Mass) × 100

Table 1 shows the compositions of the catalysts obtained in each Example and Comparative Example. The numerical values in Table 1 indicate the atomic ratio of each element.
Moreover, in each Example and Comparative Example, the ratio of the precipitated particles having a particle diameter of 1 μm or more and less than 10 μm among the precipitated particles having a particle diameter of 1 μm or more and less than 150 μm included in the aqueous slurry subjected to the drying step, the particle diameter Table 2 shows the ratio of the precipitated particles having a particle size of 10 μm or more and less than 150 μm, the final firing conditions (temperature, time) in the firing step, and the activity test conditions and results.

[Example 1]
The composition is Mo ₁₂ Bi _0.7 Fe _1.5 K _0.1 Rb _0.05 Co _1.8 Ni _4.5 Mg _1.0 Cr _0.6 W _0.4 La _0.2 Ce _0.4 P A catalyst represented by _0.2 O _x (SiO ₂ ) ₃₅ (the atomic ratio x of oxygen is a value naturally determined by the valence of other elements; hereinafter the same) was produced in the following manner.
In 850 parts of pure water, 432.6 parts of ammonium paramolybdate were dissolved (solution A).
Separately, 550 parts of 17% by mass nitric acid, 123.8 parts of ferric nitrate, 2.1 parts of potassium nitrate, 1.5 parts of rubidium nitrate, 107.0 parts of cobalt nitrate, 267.2 parts of nickel nitrate, 52. 4 parts, 49.0 parts of chromium nitrate, 17.7 parts of lanthanum nitrate, 35.5 parts of cerium nitrate and 59.5 parts of bismuth nitrate were sequentially added and dissolved (solution B).
While stirring 1073.5 parts of 40 mass% silica sol at a rotational speed of 250 rpm, A liquid, B liquid, 37.9 parts of 50 mass% ammonium metatungstate solution and 4.7 parts of 85 mass% phosphoric acid were sequentially added. An aqueous slurry was obtained.
The ratio of the precipitated particles having a particle diameter of 1 μm or more and less than 10 μm is 68% by volume and the ratio of the precipitated particles having a particle diameter of 10 μm or more and less than 150 μm among the precipitated particles of 1 μm or more and less than 150 μm in the aqueous slurry. Atomization treatment was performed using a homogenizer until the amount became 32% by volume.
The aqueous slurry after the atomization treatment was spray-dried with a rotary disk spray dryer at an inlet temperature of 270 ° C. and an outlet temperature of 180 ° C. The obtained dried powder was baked by standing in a box-type electric furnace at 250 ° C. for 2 hours and at 450 ° C. for 2 hours, and finally fluidly baked at 580 ° C. for 3 hours to obtain a composite oxide catalyst.
The obtained catalyst was subjected to an activity test.

[Example 2]
The composition is Mo ₁₂ Bi _1.2 Fe _1.8 Rb _0.05 Cs _0.03 Co _2.0 Ni _5.0 Cu _0.2 Zn _1.0 Cr _0.8 W _0.3 V _0.1 Zr A catalyst represented by _0.2 Ce _0.4 Sb _0.2 O _x (SiO ₂ ) ₅₀ was produced in the following manner.
Ammonium paramolybdate 349.7 parts was dissolved in 700 parts of pure water (solution C).
Separately, 700 parts of 17% by mass nitric acid, 120.0 parts of ferric nitrate, 1.2 parts of rubidium nitrate, 1.0 part of cesium nitrate, 96.1 parts of cobalt nitrate, 240.0 parts of nickel nitrate, 2. 1 part, 49.1 parts of zinc nitrate, 52.8 parts of chromium nitrate, 8.8 parts of zirconium oxynitrate, 28.7 parts of cerium nitrate and 96.1 parts of bismuth nitrate were sequentially added and dissolved (solution D).
Separately, 12.9 parts of ammonium paratungstate was dissolved in 500 g of pure water (solution E).
Separately, 1.9 parts of ammonium metavanadate was dissolved in 400 g of pure water (F solution).
While stirring 1239.6 parts of 40 mass% silica sol at a rotation speed of 10 rpm, C liquid, D liquid, E liquid, F liquid and 4.8 parts of antimony trioxide powder were sequentially added to obtain an aqueous slurry.
The ratio of the precipitated particles having a particle diameter of 1 μm or more and less than 10 μm is 64% by volume and the ratio of the precipitated particles having a particle diameter of 10 μm or more and less than 150 μm among the precipitated particles of 1 μm or more and less than 150 μm in the aqueous slurry. Atomization treatment was performed using a homogenizer until the amount became 36% by volume.
The aqueous slurry after the atomization treatment was spray-dried with a rotary disk spray dryer at an inlet temperature of 270 ° C. and an outlet temperature of 180 ° C. The obtained dried powder was baked by standing in a box-type electric furnace at 250 ° C. for 2 hours and at 450 ° C. for 2 hours, and finally fluidly baked at 610 ° C. for 3 hours to obtain a composite oxide catalyst.
The obtained catalyst was subjected to an activity test.

[Example 3]
The composition is Mo ₁₂ Bi _0.8 Fe _1.1 K _0.2 Co _1.2 Ni _6.0 Mn _0.2 Cr _1.0 W _0.5 Ce _0.4 Pr _0.1 Nd _0.1 In A catalyst represented by _0.1 Te _0.1 O _x (SiO ₂ ) ₄₀ was produced in the following manner.
In 2000 parts of pure water, 400.2 parts of ammonium paramolybdate was dissolved (solution G).
Separately, 2500 parts of 5% by weight nitric acid, 83.9 parts of ferric nitrate, 3.8 parts of potassium nitrate, 66.0 parts of cobalt nitrate, 329.6 parts of nickel nitrate, 10.8 parts of manganese nitrate, 75.6 parts of chromium nitrate Part, 32.8 parts of cerium nitrate, 8.2 parts of praseodymium nitrate, 8.3 parts of neodymium nitrate, 2.2 parts of indium nitrate, and 73.3 parts of bismuth nitrate were sequentially added and dissolved (liquid H).
Separately, 4.3 parts of telluric acid was dissolved in 100 parts of pure water (solution I).
While stirring the G liquid at a rotation speed of 10 rpm, the H liquid, 114.8 parts of 40 mass% silica sol, the I liquid, and 43.8 parts of 50 mass% ammonium metatungstate were sequentially added to obtain an aqueous slurry.
The obtained aqueous slurry was stirred for 20 hours at room temperature as it was, and subjected to aging treatment.
The aqueous slurry after the aging treatment is composed of 74% by volume of the precipitated particles having a particle size of 1 μm or more and less than 10 μm among the precipitated particles of 1 μm or more and less than 150 μm in the aqueous slurry, and the precipitated particles having a particle size of 10 μm or more and less than 150 μm. The atomization process was performed using a homogenizer until the ratio reached 26% by volume.
The aqueous slurry after the atomization treatment was spray-dried with a rotary disk spray dryer at an inlet temperature of 270 ° C. and an outlet temperature of 180 ° C. The obtained dried powder was baked by standing in a box-type electric furnace at 250 ° C. for 2 hours and at 450 ° C. for 2 hours, and finally fluidly baked at 600 ° C. for 3 hours to obtain a composite oxide catalyst.
The obtained catalyst was subjected to an activity test.

[Example 4]
The composition is Mo ₁₂ Bi _0.4 Fe _1.5 K _0.1 Cs _0.06 Co _1.0 Ni _5.5 Mg _1.0 Ba _0.1 Cr _0.7 W _1.0 Ce _1.0 Sm A catalyst represented by _0.1 B _0.2 O _x (SiO ₂ ) ₆₀ was produced in the following manner.
In 650 parts of pure water, 321.7 parts of ammonium paramolybdate were dissolved (solution J).
Separately, 17 parts by mass of nitric acid 300 parts ferric nitrate 92.0 parts, potassium nitrate 1.5 parts, cesium nitrate 1.8 parts, cobalt nitrate 44.2 parts, nickel nitrate 242.8 parts, magnesium nitrate 38.9 Part, 4.0 parts of barium nitrate, 42.5 parts of chromium nitrate, 65.9 parts of cerium nitrate, 6.75 parts of samarium nitrate and 29.5 parts of bismuth nitrate were sequentially added and dissolved (solution K).
Separately, 1.9 parts of boric acid was dissolved in 40 parts of pure water (Liquid L).
While stirring 1368.3 parts of 40 mass% silica sol at 250 rpm, liquid J, liquid K, liquid L and 70.4 parts of 50 mass% ammonium metatungstate aqueous solution were sequentially added to obtain an aqueous slurry.
In the obtained aqueous slurry, among precipitated particles of 1 μm or more and less than 150 μm in the aqueous slurry, the proportion of precipitated particles having a particle size of 1 μm or more and less than 10 μm is 53% by volume, and the proportion of precipitated particles having a particle size of 10 μm or more but less than 150 μm Sonication was carried out until the amount reached 47% by volume.
The aqueous slurry after the ultrasonic treatment was spray-dried with a rotary disk spray dryer at an inlet temperature of 270 ° C. and an outlet temperature of 180 ° C. The obtained dried powder was baked by standing in a box-type electric furnace at 250 ° C. for 2 hours and 450 ° C. for 2 hours, and finally fluidly baked at 570 ° C. for 3 hours to obtain a composite oxide catalyst.
The obtained catalyst was subjected to an activity test.

[Comparative Example 1]
A catalyst having the same composition as in Example 1 was prepared in the same manner as in Example 1.
However, in the obtained aqueous slurry, among the precipitated particles having a particle diameter of 1 μm or more and less than 150 μm in the aqueous slurry, the ratio of the precipitated particles having a particle diameter of 1 μm or more but less than 10 μm is 96% by volume, and the precipitated particles having a particle diameter of 10 μm or more but less than 150 μm The atomization treatment was performed using a homogenizer until the ratio of 4 became 4% by volume.
The obtained catalyst was subjected to an activity test.

[Comparative Example 2]
A catalyst having the same composition as in Example 1 was produced as follows.
In 2000 parts of pure water, 432.6 parts of ammonium paramolybdate were dissolved (M solution).
Separately, 2500 parts of 5% by mass nitric acid, 123.8 parts of ferric nitrate, 2.1 parts of potassium nitrate, 1.5 parts of rubidium nitrate, 107.0 parts of cobalt nitrate, 267.2 parts of nickel nitrate, 52. 4 parts, 49.0 parts of chromium nitrate, 17.7 parts of lanthanum nitrate, 35.5 parts of cerium nitrate, and 59.5 parts of bismuth nitrate were sequentially added and dissolved (N solution).
While stirring 1073.5 parts of 40 mass% silica sol at a rotation speed of 10 rpm, M liquid, N liquid, 37.9 parts of 50 mass% ammonium metatungstate solution and 4.7 parts of 85 mass% phosphoric acid were sequentially added. An aqueous slurry was obtained. The obtained aqueous slurry was kept at room temperature for 24 hours.
Stirring was continued for a time and an aging treatment was performed.
When the particle size distribution of the precipitated particles in the aqueous slurry after the aging treatment was measured, among the precipitated particles of 1 μm or more and less than 150 μm in the aqueous slurry, the proportion of the precipitated particles having a particle diameter of 1 μm or more and less than 10 μm was 26% by volume, particles The ratio of precipitated particles having a diameter of 10 μm or more and less than 150 μm was 74% by volume.
This aqueous slurry was spray-dried with a rotary disk spray dryer at an inlet temperature of 270 ° C. and an outlet temperature of 180 ° C. The obtained dry powder was baked by standing in a box-type electric furnace at 250 ° C. for 2 hours and at 450 ° C. for 2 hours, and finally fluidly baked at 580 ° C. for 3 hours to obtain a composite oxide catalyst.
The obtained catalyst was subjected to an activity test.

[Comparative Example 3]
A catalyst having the same composition as in Example 3 was prepared in the same manner as in Example 3.
However, the aqueous slurry after the aging treatment was not atomized and spray-dried as it was.
When the particle size distribution of the precipitated particles in the aqueous slurry after the aging treatment was measured, among the precipitated particles of 1 μm or more and less than 150 μm in the aqueous slurry, the proportion of the precipitated particles having a particle diameter of 1 μm or more and less than 10 μm was 24% by volume, The ratio of precipitated particles having a particle size of 10 μm or more and less than 150 μm was 76% by volume.
The obtained catalyst was subjected to an activity test.

[Comparative Example 4]
A catalyst having the same composition as in Example 3 was prepared in the same manner as in Example 3.
However, the aqueous slurry after the aging treatment is a precipitate in which the proportion of precipitated particles having a particle diameter of 1 μm or more but less than 10 μm is 93% by volume and the particle diameter is 10 μm or more but less than 150 μm among the precipitated particles of 1 μm or more and less than 150 μm in the aqueous slurry. The atomization process was performed using a homogenizer until the ratio of the particles became 7% by volume.
The obtained catalyst was subjected to an activity test.

As is clear from Table 2, all of the composite oxide catalysts obtained in Examples 1 to 4 were able to synthesize acrylonitrile in high yield.
On the other hand, although the composite oxide catalysts obtained in Comparative Examples 1 and 2 have the same composition as the composite oxide catalyst obtained in Example 1, the yield of acrylonitrile is lower than that in Example 1. It was.
In addition, the composite oxide catalyst obtained in Comparative Examples 3 and 4 has a lower acrylonitrile yield than Example 3 although it has the same composition as the composite oxide catalyst obtained in Example 3. It was.

Claims (1)

A step of preparing an aqueous slurry comprising at least molybdenum, bismuth, iron, and silica, and comprising a liquid phase and a solid phase; a step of drying the aqueous slurry to obtain a dried product; and the obtained dried product And a step of calcining at a temperature in the range of 500 to 750 ° C., in the method for producing a composite oxide catalyst for acrylonitrile synthesis,
Of the precipitated particles having a particle diameter of 1 μm or more and less than 150 μm, contained in the aqueous slurry, the ratio of the precipitated particles having a particle diameter of 1 μm or more and less than 10 μm is 53 to 74 % by volume, and the precipitated particles having a particle diameter of 10 μm or more and less than 150 μm. manufacturing method of synthesizing acrylonitrile composite oxide catalyst, wherein the proportion of is from 26 to 47 vol%.