JP6914114B2 - Metal oxide catalyst and its production method and acrylonitrile production method using it - Google Patents

Description

The present invention relates to a metal oxide catalyst and a method for producing the same, and a method for producing acrylonitrile using the same. The present invention is a catalyst particularly suitable for use in producing acrylonitrile by reacting propylene with molecular oxygen and ammonia. Regarding.

A method for producing acrylonitrile by reacting propylene with molecular oxygen and ammonia (ammoxidation reaction) is well known. Many catalysts used for this ammoxidation reaction have also been proposed.

Various elements are applied to the catalyst used in the production of acrylonitrile, and there are many exemplified components. For such a multi-element composite oxide catalyst, the combination of components and the improvement of the composition are made. Is being considered. For example, Patent Document 1 contains molybdenum, bismuth and iron as essential elements, contains elements such as nickel, potassium, cerium, magnesium and rubidium as optional components, and is a silica raw material used for producing silica as a catalyst carrier. A granular porous ammoxidation catalyst characterized by is described in.

Further, Patent Document 2 describes a catalyst containing rubidium, cerium, chromium, magnesium, iron, bismuth and molybdenum as essential elements and nickel or at least one of nickel and cobalt. Further, Patent Document 3 describes a catalyst in which molybdenum, bismuth, iron, chromium, cerium, nickel, magnesium, cobalt, manganese, potassium and rubidium are essential elements and any other element is used.

Furthermore, Patent Documents 4 and 5 describe catalysts characterized in that the types of elements and the range of component concentrations are specified by a predetermined general formula, and the atomic ratios of these elements satisfy a certain relationship. Will be done.
In addition to the above, as catalysts shown in recent literature, those having specified the physical properties and crystallinity of the catalyst, and methods for obtaining a high-performance catalyst by a predetermined production method have been proposed. More specifically, those characterized by the size and the ratio of the metal oxide particles in the catalyst particles (see, for example, Patent Document 6), those in which an alkali metal is introduced into the catalyst by an impregnation operation (for example, Patent Document 7). (See), and those in which the X-ray diffraction peak ratio of the catalyst composition is specified (see, for example, Patent Document 8) have been proposed, and each of them has an effect of improving the yield of the target product, acrylonitrile. Has been described.

Japanese Patent No. 5188005 Japanese Patent No. 4709549 Japanese Patent No. 4588533 Japanese Patent No. 501167 Japanese Patent No. 5491037 Japanese Unexamined Patent Publication No. 2013-17917 Japanese Unexamined Patent Publication No. 2013-169482 Japanese Patent Application Laid-Open No. 2014-522038 Japanese Unexamined Patent Publication No. 2013-146655 Japanese Patent No. 5371692

The yield of acrylonitrile obtained when the catalysts described in the above-mentioned documents are used has been improved from the past, but as is clear from the descriptions in these documents, the by-products in the reaction are still present. exist. As described above, further improvement in the yield of the target product, acrylonitrile, is desired. In addition, by reducing the by-products of the reaction, the load related to the separation, recovery, and treatment of the target product and the by-products can be reduced, which is expected to have an environmental effect. Therefore, there is a need for a method for reducing by-products in the production of acrylonitrile, that is, a catalyst capable of achieving a high yield, without being limited to the prior art. Further, in order to achieve such a high yield, it is important to reduce the consumption of raw materials and to maintain a high yield stably for a long period of time, and for that purpose, including life performance, shape and strength. A catalyst having excellent practicality and handleability is required.
Further, there is a problem in the prior art with respect to the manufacturing method thereof. For example, Patent Document 9 requires a very complicated process of preparing a catalyst precursor once, drying and firing the precursor, pulverizing the catalyst precursor, and preparing the catalyst again. Further, although a method for producing a catalyst is disclosed in Patent Document 10, even with this method, a catalyst having sufficiently high catalytic performance cannot be obtained.

Therefore, an object of the present invention is to provide a metal oxide catalyst which is a MoBi-containing metal oxide catalyst and has higher catalytic performance, and a method for producing such a catalyst.

As a result of diligent studies by the present inventors to solve the above problems, the conventional MoBi-containing metal oxide catalyst has a non-uniform composition ratio of Mo and Bi on its surface, and this is sufficient. It turned out that the excellent catalytic performance was not exhibited.
Further, the MoBi-containing metal oxide catalyst is generally produced by using a slurry-like MoBi-containing liquid obtained by mixing a Mo-containing liquid and a Bi-containing liquid. It has been found that the mixing method has a great influence on the uniformity of the composition ratio of Mo and Bi on the surface of the catalyst. Then, if the Mo-containing liquid and the Bi-containing liquid are mixed by a specific method at the time of preparing the slurry, a MoBi-containing metal oxide catalyst for an ammoxidation reaction in which the composition ratio of Mo and Bi on the catalyst surface is uniform can be produced. And completed the present invention.

That is, the present invention is as follows.
[1] A catalyst composed of particles containing a metal oxide having a bulk composition represented by the following formula (1).
The standard deviation of the value obtained by dividing the ratio of the Bi-molar concentration to the Mo-molar concentration on the surface of the catalyst particles by the ratio of the Bi-molar concentration to the Mo-molar concentration of the metal oxide bulk is 0.2 or less.
catalyst.
_{Mo 12 Bi a Fe b X c} Y d Z e O f (1)
(In formula (1), X is one or more elements selected from the group consisting of nickel, cobalt, magnesium, calcium, zinc, strontium and barium, and Y is cerium, chromium, lantern, neodymium, ittrium, placeodium, and samarium. , One or more elements selected from the group consisting of aluminum, gallium and indium, Z represents one or more elements selected from the group consisting of potassium, rubidium and strontium, and a, b, c, d and e are. 0.1 ≦ a ≦ 2.0, 0.1 ≦ b ≦ 3.0, 0.1 ≦ c ≦ 10.0, 0.1 ≦ d ≦ 3.0, and 0.01 ≦ e ≦ 2, respectively. Satisfying .0, f is the number of oxygen atoms required to satisfy the valence requirements of the other existing elements.)
[2] The catalyst according to [1], wherein the particles further contain silica.
[3] A method for producing a catalyst containing a metal oxide having a bulk composition represented by the following formula (1).
(I) A step of preparing a Mo-containing liquid containing at least Mo and a Bi-containing liquid containing at least Bi.
(Ii) The Mo-containing liquid is continuously supplied to the first flow path, the Bi-containing liquid is continuously supplied to the second flow path, and the first flow path and the second flow path To obtain a MoBi-containing liquid by mixing the Mo-containing liquid and the Bi-containing liquid by merging the Mo-containing liquid and the Bi-containing liquid downstream from the respective supply points, and (iii) the MoBi. The process of drying the contained liquid,
Including methods.
_{Mo 12 Bi a Fe b X c} Y d Z e O f (1)
(In formula (1), X is one or more elements selected from the group consisting of nickel, cobalt, magnesium, calcium, zinc, strontium and barium, and Y is cerium, chromium, lantern, neodymium, ittrium, placeodium, and samarium. , One or more elements selected from the group consisting of aluminum, gallium and indium, Z represents one or more elements selected from the group consisting of potassium, rubidium and strontium, and a, b, c, d and e are. 0.1 ≦ a ≦ 2.0, 0.1 ≦ b ≦ 3.0, 0.1 ≦ c ≦ 10.0, 0.1 ≦ d ≦ 3.0, and 0.01 ≦ e ≦ 2, respectively. Satisfying .0, f is the number of oxygen atoms required to satisfy the valence requirements of the other existing elements.)
[4] Between the step (iii) and the step (iii), further
(Iv) The method for producing a catalyst according to [3], which comprises a step of further mixing the MoBi-containing liquid.
[5] Between the step (iii) and the step (iii), further
(V) The method for producing a catalyst according to [3] or [4], which comprises a step of storing the MoBi-containing liquid.
[6] The series of processes of the steps (i), (ii) and (v) are performed by a batch processing method, and the total amount of the MoBi-containing liquid obtained in the step (ii) for one batch is obtained in the step (v). The method for producing a catalyst according to [5], which is stored.
In the step (ii), the mass supply rates of the Mo-containing liquid and the Bi-containing liquid to the first flow path or the second flow path are set to mA (g / min) and mb (g / g, respectively). When it is set to min), 60% by mass or more of the total amount of the total supply amounts MA (g) and MB (g) per batch of the Mo-containing liquid and the Bi-containing liquid satisfies the formula (2). A method of manufacturing a catalyst to be supplied to.
(MB / mA) / (MB / MA) = 0.5 to 1.5 (2)
[7] The method for producing a catalyst according to [3] or [4], wherein the MoBi-containing liquid is continuously supplied to the step (iii).
[8] In the step (ii), the molar supply rates of the Mo-containing liquid and the Bi-containing liquid to the first flow path or the second flow path are set to mα (mol / min) and mβ (mol), respectively. / Min)
The Mo-containing liquid and the Bi-containing liquid are supplied so as to satisfy the formula (3).
The method for producing a catalyst according to [3], [4] or [7].
(Mβ / mα) / (a / 12) = 0.8 to 1.2 (3)
[9] A method for producing acrylonitrile, which comprises a step of reacting propylene, molecular oxygen, and ammonia in the presence of the catalyst according to [1] or [2].

According to the present invention, it is possible to provide a MoBi metal oxide catalyst having excellent catalytic performance and a method for continuously and stably producing such a catalyst.
Furthermore, according to the present invention, by using the MoBi metal oxide catalyst as described above, acrylonitrile can be stably produced from propylene in a high yield for a long period of time.

It is a conceptual diagram which shows an example of the catalyst manufacturing apparatus which concerns on this invention. It is the schematic which shows an example of the stationary mixer.

Hereinafter, a mode for carrying out the present invention (hereinafter, also simply referred to as “the present embodiment”) will be described in detail. The present invention is not limited to the following embodiments, and can be variously modified and implemented within the scope of the gist thereof.

The catalyst of the present embodiment (hereinafter, also simply referred to as “catalyst”) contains a metal oxide having a bulk composition containing Mo and Bi represented by the following general formula (1), and preferably the metal oxidation. It consists of a substance and a carrier such as silica.
_{Mo 12 Bi a Fe b X c} Y d Z e O f (1)
(In formula (1), X is one or more elements selected from the group consisting of nickel, cobalt, magnesium, calcium, zinc, strontium and barium, and Y is cerium, chromium, lantern, neodymium, ittrium, placeodium, and samarium. , One or more elements selected from the group consisting of aluminum, gallium and indium, Z represents one or more elements selected from the group consisting of potassium, rubidium and strontium, and a, b, c, d and e are. 0.1 ≦ a ≦ 2.0, 0.1 ≦ b ≦ 3.0, 0.1 ≦ c ≦ 10.0, 0.1 ≦ d ≦ 3.0, and 0.01 ≦ e ≦ 2, respectively. Satisfying .0, f is the number of oxygen atoms required to satisfy the valence requirements of the other existing elements.)

Since the catalyst of the present embodiment contains the metal oxide having the bulk composition, it exhibits a high acrylonitrile selectivity in the ammoxidation reaction and has good wear strength that can withstand long-term use as a fluidized bed catalyst. ..
The present inventors consider this as follows. The active site in the ammoxidation reaction is bismuth-containing molybdate, but a high acrylonitrile selectivity cannot be obtained by itself. It is considered that the acrylonitrile selectivity is improved when the bismuth-containing molybdate is uniformly compounded with the iron-containing molybdate and the molybdate containing other metals, at least on the surface of the catalyst particles.
In addition, the catalyst particles in which bismuth-containing molybdate is uniformly complexed with iron-containing molybdate and molybdate containing other metals on the surface thereof agglomerate each metal component as a single component at the stage of its precursor slurry. It is considered necessary to disperse the particles without allowing them to be dispersed so that the moribdate containing bismuth can be easily compounded with the moribdate containing other metals. Further, when the metal particles are supported on the carrier, it is considered that the abrasion strength of the catalyst is also improved by preventing the agglomeration of both the metal in the precursor slurry and the particles of the carrier.
However, the mechanism of action is not limited to the above.

[composition]
The metal oxide constituting the catalyst in the present embodiment contains molybdenum, bismuth, and iron as essential components. Molybdenum plays a role as an adsorption site for propylene and an activation site for ammonia. In addition, bismuth plays a role of activating propylene and abstracting hydrogen at the α-position to produce π-allyl species. Furthermore, iron plays a role of supplying oxygen present in the gas phase to the catalytic active site by trivalent / divalent redox.

In addition, as optional components that may be contained in the metal oxide, one or more elements X, cerium, chromium, lantern, selected from the group consisting of nickel, cobalt, magnesium, calcium, zinc, strontium and barium, Examples thereof include one or more elements Y selected from the group consisting of neodymium, ittrium, praseodymium, strontium, aluminum, gallium and indium, and one or more elements Z selected from the group consisting of potassium, rubidium and cesium. The element X forms a molybdate with moderate lattice defects and plays a role in facilitating the movement of oxygen in the bulk. The element Y, like iron, has a redox function in the catalyst. Further, the element Z plays a role of suppressing the decomposition reaction of the main product and the raw material by blocking the acid spot existing on the surface of the catalyst particles.

As mentioned above, each element has its own role in functioning as a catalyst, and elements that can substitute for the function of the element, elements that cannot substitute for the function, elements that bring about an auxiliary effect of the function, and the like. The elements and composition ratio that should be selectively added vary depending on the elemental composition and composition of the catalyst.

The bulk composition of the metal oxide constituting the catalyst of the present embodiment, that is, the ratio of each element constituting the entire metal oxide is represented by the following general formula (1).
Having such a composition tends to further improve the acrylonitrile selectivity.
_{Mo 12 Bi a Fe b X c} Y d Z e O f (1)
In the above formula (1), X is one or more elements selected from the group consisting of nickel, cobalt, magnesium, calcium, zinc, strontium and barium, and Y is cerium, chromium, lantern, neodymium, ittrium, praseodymium and samarium. , One or more elements selected from the group consisting of aluminum, gallium and indium, Z indicates one or more elements selected from the group consisting of potassium, rubidium and cesium.
a indicates the atomic ratio of bismuth to 12 atoms of molybdenum, which is 0.1 ≦ a ≦ 2.0, preferably 0.15 ≦ a ≦ 1.0, and more preferably 0.2 ≦ a ≦ 0. .7 and
b represents the atomic ratio of iron to 12 atoms of molybdenum, which is 0.1 ≦ b ≦ 3.0, preferably 0.5 ≦ b ≦ 2.5, and more preferably 1.0 ≦ b ≦ 2. .0 and
c represents the atomic ratio of X to 12 atoms of molybdenum, 0.1 ≦ c ≦ 10.0, preferably 3.0 ≦ c ≦ 9.0, and more preferably 5.0 ≦ c ≦ 8. .5 and
d indicates the atomic ratio of Y to 12 atoms of molybdenum, which is 0.1 ≦ d ≦ 3.0, preferably 0.2 ≦ d ≦ 2.0, and more preferably 0.3 ≦ d ≦ 1. .5 and
e indicates the atomic ratio of Z to 12 atoms of molybdenum, which is 0.01 ≦ e ≦ 2.0, preferably 0.05 ≦ e ≦ 1.0.
f indicates the atomic ratio of oxygen to 12 atoms of molybdenum, and is the number of oxygen atoms required to satisfy the valence requirements of other existing elements.

The bulk composition (each element ratio) of the metal oxide is determined by the charging ratio of the raw materials at the time of synthesizing the catalyst and well-known element quantitative analysis methods such as ICP emission spectroscopy, atomic absorption spectroscopy, and ICP mass spectrometry. It can be obtained by a fluorescent X-ray analysis method or the like.
The ICP emission spectroscopic analysis method is the method adopted in the examples, and the specific procedure thereof will be described in the examples. Further, in the case of quantitative analysis by fluorescent X-ray analysis, for example, using a fluorescent X-ray apparatus (for example, ZSX100e manufactured by Rigaku (tube: Rh-4KW, spectroscopic crystal: LiF, PET, Ge, RX25)), each Quantitative analysis of the catalyst sample can be performed based on the calibration curve that corrects the matrix effect of the elements. When the catalyst is produced by the production method of the present embodiment described later, the values obtained by such analysis are substantially the same as the design-prepared composition. Further, according to these elemental quantitative analyzes, it is possible to determine the bulk composition of the catalyst in use as well as the catalyst before use.

When industrially producing acrylonitrile, a fluidized bed reaction in which the catalyst is flowed by a reaction gas is generally selected. Therefore, when the catalyst of the present embodiment is used as a catalyst for ammoxidation, it is preferable that the catalyst has a certain strength or higher. From this point of view, in the catalyst of the present embodiment, the metal oxide may be supported on the carrier. The carrier is not particularly limited, and examples thereof include oxides such as silica, alumina, titania, and zirconia. Among these, silica, which has a small decrease in selectivity of acrylonitrile and can greatly improve the wear resistance and particle strength of the catalyst, is suitable as a carrier.

The content of the carrier is preferably 30 to 70% by mass, more preferably 35 to 65% by mass, based on 100% by mass of the catalyst. When the content of the carrier is 30% by mass or more, the abrasion resistance and the particle strength of the ammoxidation reaction catalyst tend to be further improved. Further, when the content of the carrier is 70% by mass or less, the acrylonitrile selectivity tends to be further improved.

In the present embodiment, the shape of the catalyst particles is not limited, but is preferably spherical. The average particle size of the catalyst particles is preferably in the range of 40 to 70 μm, more preferably in the range of 45 to 65 μm. As for the particle size distribution, the amount of catalyst particles having a particle diameter of 5 to 200 μm is preferably 90 to 100% by mass with respect to the total mass of the catalyst. The amount of particles having a particle diameter of 45 μm or less is preferably 10 to 50% by volume, more preferably 15 to 35% by volume, based on the total volume of the particles.

Further, the catalyst of the present embodiment preferably has excellent wear resistance so that it can be used as a fluidized bed catalyst. In particular, in the fluidized bed reaction, the catalyst particles have abrasion resistance that does not wear or crush due to impacts such as contact between catalyst particles in the reactor, collision with the wall surface of the reactor, contact with gas, etc. From this point of view, the catalyst of the present embodiment is a fluidized bed catalyst wear test (“Test Method for Synthetic Fluid Cracking Catalyst” (American Canadian Co. Ltd. 6 / 31-4m-1 / 57)). The wear loss in the test according to the method described in (1) is preferably 2.5% or less.

Further, the apparent specific gravity of the catalyst particles of the present embodiment is preferably in the range of 0.85 to 1.15 g / cc. When the apparent specific gravity of the catalyst particles is 0.85 g / cc or more, the influence of the bulkiness of the catalyst particles at the time of charging into the reactor can be reduced, and the required volume of the reactor tends to be reduced. , There is a tendency that it is possible to effectively prevent the occurrence of catalyst loss due to an increase in the amount of catalyst scattered from the reactor to the outside. Further, when the apparent specific gravity of the catalyst particles is 1.15 g / cc or less, a good flow state of the catalyst particles can be ensured, and deterioration of the reaction performance tends to be effectively prevented.
The apparent specific gravity of the catalyst particles is determined by placing the sample (catalyst particles) in a container of a certain volume in a constant state, measuring the mass of the sample in the container, and calculating the mass per unit volume. Can be sought.
For example, a 25 ml glass graduated cylinder (hereinafter, simply referred to as “graduated cylinder”) is placed directly under the glass funnel, and a measurement sample (catalyst particles) shaken well in advance is dropped onto the glass funnel, and the sample is sampled until the graduated cylinder overflows. Is thrown in. Remove the convex part of the sample accumulated above the mouth of the graduated cylinder by scraping off, and brush the sample adhering to the outer wall of the graduated cylinder with a brush or the like. The apparent specific gravity is calculated by obtaining the mass of the sample from the mass of the measuring cylinder containing the sample and the mass of the measuring cylinder measured in advance, and dividing it by the volume of the measuring cylinder.

In the present embodiment, the ratio of the Bi-molar concentration to the Mo-molar concentration on the surface of the catalyst particles ((Bi / Mo) _surf ) of the catalyst containing the metal oxide having the bulk composition represented by the formula (1) is determined by metal oxidation. The standard deviation of the value divided by the ratio of the Bi molar concentration to the Mo molar concentration of the product bulk ((Bi / Mo) _{bulk) is 0.2 or less.}
Here, the Momol concentration and the Bimol concentration on the particle surface can be determined by SEM-EDX (Scanning Electron Microscopic X-ray Spectroscopy: scanning electron microscope-energy dispersive X-ray spectroscopy) composition analysis. As described above, the Mo molar concentration and the Bi molar concentration of the metal oxide bulk can be determined, for example, by ICP emission spectroscopy.
Further, the standard deviation can be obtained by the following equation (4).
Standard deviation = {((S ₁ − μ) ² + (S ₂ − μ) ² + ・ ・ ・ + (S ₁₀₀ − μ) ² ) / 100 [Number]} ^1/2 (4)
In formula (4), Sk (k = 1 to 100) is the ratio of the measured Bi-molar concentration to the Mo-molar concentration on the surface of the k-th particle in the arbitrarily selected 100 particles (Bi / Mo). _{It is a value obtained by dividing surf} by the ratio of Bi molar concentration to Mo molar concentration (Bi / Mo) _bulk of the metal oxide bulk, and μ is the average value of 100 Sk (k = 100) (= (S ₁ +). S ₂ ... + S ₁₀₀ ) / 100).
Standard deviation is an indicator of variability. The smaller the standard deviation, the smaller the variation from the average value. Therefore, the smaller the value of the formula (4), the more uniform the surface composition of the particles.
According to the research by the present inventors, it has been found that the yield of acrylonitrile increases when a catalyst having a small value of the formula (4) is used in producing acrylonitrile by the ammoxidation reaction of propylene. In the present embodiment, the value of the formula (4) is 0.2 or less, preferably 0.15 or less, more preferably 0.10 or less, and further preferably 0.07 or less. preferable.

[Manufacturing method of metal oxide catalyst]
The catalyst containing a metal oxide having a uniform surface composition and a bulk composition represented by the formula (1) may be referred to as, for example, the production method of the present embodiment (hereinafter, "first production method"). ) Can be manufactured.
The first production method is (i) a step of preparing a Mo-containing liquid containing at least Mo and a Bi-containing liquid containing at least Bi, and (ii) mixing the Mo-containing liquid and the Bi-containing liquid. It includes a step of obtaining a MoBi-containing liquid, and further includes a step of drying the (iii) MoBi-containing liquid. After the (iii) step, a firing step may be further included.

Further, in the first production method, after the Mo-containing liquid and the Bi-containing liquid are mixed to generate a MoBi-containing liquid (slurry), before the step of drying the MoBi-containing liquid (that is, the step (ii)). And (between steps (iii)), a step (step (iv)) of further mixing the MoBi-containing liquid can be provided.
Further, a step ((v) step) of storing a certain amount of the MoBi-containing liquid can be provided between the (ii) step and the (iii) step.
The MoBi-containing liquid prepared in the step (iii) may be continuously supplied to the step (iii) as it is, may be supplied to the step (iii) after the step (iv), or a part thereof. Alternatively, the entire amount may be temporarily stored (step (v)) and then supplied to step (iii).
When step (v) is provided and the MoBi-containing liquid is temporarily stored, the total amount of the MoBi liquid prepared in the step (ii) or the total amount of the MoBi-containing liquid prepared by performing the step (iv) after the step (ii). It is preferable to store (batch processing method). In the case of the batch processing method, even if the supply ratio of the Mo-containing liquid and the Bi-containing liquid is deviated in the step (ii), the entire amount of the raw materials is mixed in the step (v), that is, the intended composition. The homogenized MoBi-containing liquid can be sent to the (iii) step.
In the present embodiment, it does not matter whether the continuous supply method or the batch processing method is selected, but the continuous processing method is used when the catalyst is to be produced in a short time, and the batch processing is used when the allowable range of the deviation of the supply ratio is widened. It is preferable to select the method.

The details of the first manufacturing method will be described below.
Steps (i) and (ii) are steps of preparing a slurry containing a metal oxide raw material.
Specifically, (i) a Mo-containing liquid containing at least Mo (a liquid containing a raw material of Mo which is a component of a metal oxide, hereinafter also referred to as "Liquid A") and Bi containing at least Bi. It includes a step of preparing a containing liquid (a liquid containing a raw material of Bi which is a component of a metal oxide and also referred to as "B liquid") and (ii) a step of mixing both (hereinafter, Mo-containing liquid and the like). The Bi-containing liquid is sometimes referred to as "two liquids"). By mixing the two liquids, a MoBi-containing liquid which is a slurry is formed.
This MoBi-containing liquid is a precursor of a MoBi-containing metal oxide, and it has been found by the studies of the present inventors that the production conditions of this precursor have a great influence on the uniformity of the surface composition of the catalyst particles to be produced. ..
In the present embodiment, in the step (ii), the Mo-containing liquid and the Bi-containing liquid are continuously supplied to the first and second flow paths, respectively, to form the first flow path and the second flow path. To prepare the MoBi-containing liquid by merging the particles downstream from the respective supply points of the Mo-containing liquid and the Bi-containing liquid, it was possible to produce catalyst particles having a highly uniform surface composition.

The atomic ratio (bulk composition) of each element in the metal oxide contained in the catalyst finally produced by this method basically changes from the atomic ratio of the raw material used at the time of production, except for oxygen atoms. do not have.

Here, the raw materials of the elements constituting the catalyst of the present embodiment will be described.
As the raw material of Mo, a salt soluble in water, nitric acid or the like is preferable, and examples thereof include ammonium molybdate, which is an ammonium salt.
As a raw material for nickel, cobalt, magnesium, calcium, zinc, strontium, barium, cerium, chromium, lantern, neodymium, ittrium, placeodium, samarium, aluminum, gallium, indium, potassium, rubidium, and cesium, water is used in the same manner as above. , Nitric acid and other soluble salts are preferred, and examples thereof include nitrates, hydrochlorides, sulfates, organic acid salts and the like. In particular, nitrate is preferable from the viewpoint of being easily dissolved in water, nitric acid and the like. For example, bismuth nitrate, iron nitrate, nickel nitrate, cobalt nitrate, potassium nitrate, rubidium nitrate, magnesium nitrate, calcium nitrate, strontium nitrate, barium nitrate, zinc nitrate, lanthanum nitrate, cerium nitrate, chromium nitrate, indium nitrate, gallium nitrate, etc. Can be mentioned. These may be used alone or in combination of two or more.

The carrier is not particularly limited, but for example, oxides such as silica (SiO ₂ ), alumina, titania, and zirconia are preferable. Among these, during the reaction for producing acrylonitrile, the decrease in selectivity of acrylonitrile is small, the number of acid points that increase by-products is small, and the wear resistance and particle strength of the catalyst can be greatly improved. , SiO ₂ is particularly preferable. The raw material of SiO ₂ is not particularly limited, and examples thereof include silica sol (also referred to as colloidal silica) and powdered silica. Silica sol is particularly preferable because of its ease of handling. For example, Snowtex (manufactured by Nissan Chemical Industries, Ltd.), Nalco silica sol (manufactured by Narco Japan), and the like.
The average primary particle size of silica contained in the silica sol is not particularly limited, but is preferably in the range of 5 to 100 nm, and more preferably in the range of 10 to 50 nm. Further, silica sol having different average primary particle diameters can be mixed and used.

From the viewpoint of enhancing the dispersibility in the Mo-containing liquid and the Bi-containing liquid of the catalyst raw material metal and the MoBi-containing liquid obtained by mixing both of them, the Mo-containing liquid, the Bi-containing liquid and the MoBi-containing liquid may be used. In addition to the raw material metal described above, it is also preferable to add an organic acid capable of forming a chelate with the metal element. The organic acid is not particularly limited, but for example, oxalic acid, tartaric acid, citric acid, malic acid and the like are preferable, and the organic acid may be added to either a Mo-containing liquid or a Bi-containing liquid, and may be added to both. It may be added. Further, it is also one of the preferable forms to add the organic acid to the raw materials of Si, Al, Ti and Zr, for example, silica sol. The organic acid can be added as its powder as well as as a solid or as an aqueous solution.
It is also preferable to add an inorganic acid such as nitric acid, hydrochloric acid, or sulfuric acid for the purpose of increasing the solubility of each metal salt of the raw material metal. Nitric acid is particularly preferable because it volatilizes during the firing step described later and has little residue on the catalyst.
Further, it is also preferable to add aqueous ammonia to the Mo-containing solution in order to increase the solubility of Mo.

In the first production method, first, a Mo-containing liquid and a Bi-containing liquid are prepared (step (i)).
The Mo-containing liquid is preferably prepared by dissolving or dispersing the raw material of Mo in an aqueous medium such as water. It is also preferable to add aqueous ammonia to this solution to increase the solubility of the Mo raw material. The Mo atom concentration in the Mo-containing liquid is preferably in the range of 0.1 to 30% by mass.
A Bi-containing liquid is prepared separately from the Mo-containing liquid. The Bi-containing liquid is preferably prepared by dissolving or dispersing the above-mentioned Bi raw material in an aqueous medium such as water. The Bi-containing liquid is preferably acidic, and it is more preferable that the Bi-containing liquid contains nitric acid because it increases the solubility of the raw material of Bi. The Bi atom concentration in the Bi-containing liquid is preferably in the range of 0.1 to 10% by mass.

Raw materials other than Mo raw materials and Bi raw materials, that is, raw materials such as Fe, Ni, Co, alkali metals, Mg, Ca, Sr, Ba, Zn, Mn, rare earths, Cr, In, Ga, Si, Al, Ti, Zr, etc. , It may be added to either the Mo-containing liquid or the Bi-containing liquid, or may be added to both, as long as no precipitate is formed. Further, it may be added to the MoBi-containing liquid after mixing the above two liquids. It is preferable to add the raw material of the metal other than Mo to the Bi-containing liquid because it is difficult for a precipitate to form, and in particular, the raw material of the metal other than Si, Al, Ti, and Zr is added to the Bi-containing liquid. It is preferable to add.

Next, the prepared Mo-containing liquid and Bi-containing liquid are mixed (step (iii)). At this time, the Mo-containing liquid and the Bi-containing liquid are continuously supplied to the first and second flow paths, respectively, and the first flow path and the second flow path are supplied to the Mo-containing liquid and the Bi-containing liquid, respectively. The Mo-containing liquid and the Bi-containing liquid are mixed by merging them downstream from the supply point of.

In the supply of the Mo-containing liquid and the Bi-containing liquid to each flow path, the supply molar ratio of Mo and Bi is the atomic number ratio of Mo and Bi in the formula (1) of the bulk composition of the metal oxide to be produced, that is, a /. It is preferable to carry out the operation so as to be substantially the same as that of No. 12, and for example, the supply molar ratio is preferably in the range of (a / 12) × 0.8 to (a / 12) × 1.2.
That is, in the step (ii), the molar supply rate of the Mo-containing liquid and the Bi-containing liquid to the first flow path or the second flow path (however, the molar supply rate of Mo and the molar supply rate of Bi, respectively) is determined. It is preferable that the Mo-containing liquid and the Bi-containing liquid are supplied so as to satisfy the following formula (3), respectively, when mα (mol / min) and mβ (mol / min) are used.
(Mβ / mα) / (a / 12) = 0.8 to 1.2 (3)

The steps (i) and (ii) were performed for each batch, and the entire amount of one batch of the MoBi-containing liquid obtained in the step (ii) was stored in the step (v) or passed through the step (iv). When a batch processing method is adopted in which the Mo-containing liquid is later stored in the step (v) and then sent to the (iii) step, the Bi-containing liquid with respect to the mass supply rate mA (g / min) of the Mo-containing liquid to the first flow path is adopted. The ratio of the mass supply rate mB (g / min) (hereinafter, also referred to as “supply ratio”) is the total amount of Bi-containing liquid per batch to the total supply amount MA (g) per batch of Mo-containing liquid. It is preferable to supply the product so as to be 0.5 to 1.5 times the ratio of the supply amount MB (g) (hereinafter, also referred to as “mass ratio”).
That is, it is preferable that the Mo-containing liquid and the Bi-containing liquid are supplied so as to satisfy the following formula (2).
(MB / mA) / (MB / MA) = 0.5 to 1.5 (2)
When the supply ratio is in the range of 0.5 times to 1.5 times the mass ratio, the uniformity of the composition of the particle surface of the catalyst can be further improved. (MB / mA) / (MB / MA) is more preferably 0.8 to 1.2, and particularly preferably 1.0.

The supply ratio (mB / mA) and mass ratio (MB / MA) will be described below with specific examples.
The bulk composition of the metal oxide to be produced is one in which a = 1 in the formula (1) (Bi1 atom with respect to Mo12 atom), and the Mo-containing liquid for one batch prepared in the step (i) is Mo. The required amount of the raw material is included and the total amount (MA) is 100 parts by mass, and the Bi-containing liquid for one batch prepared in the step (i) contains the required amount of the raw material of Bi (1 of the number of moles of Mo in the Mo-containing liquid). / 12) Including, the total amount (MB) is 50 parts by mass.
When these two liquids are represented by the ratio of the mass supply amount (mass supply rate) (g / min) per unit time and supplied at Mo-containing liquid: Bi-containing liquid = 100: 50, the mass ratio and the supply ratio are as follows. Each is as follows.
Mass ratio (MB / MA)
= 50/100 = 0.5
Supply ratio (mB / mA)
= 50/100 = 0.5
Therefore, that case corresponds to the supply ratio being 1.0 times the mass ratio.
Similarly, when the Mo-containing liquid: Bi-containing liquid = 100: 25 (mass supply rate ratio) is supplied, the supply ratio corresponds to 0.5 times the mass ratio (0.5). Mo-containing liquid: Bi-containing liquid = 100: 75 (mass supply rate ratio) (supply ratio = 75/100 = 0.75), supply ratio is 1.5 times the mass ratio (0.5) Corresponds to.
When the supply ratio is 1.0 times the mass ratio, which is a particularly preferable embodiment, in the step (ii), the total supply amount of one batch of Bi-containing liquid is equal to the total supply amount of one batch of Mo-containing liquid. The two liquids are supplied and merged at the same ratio as the ratio, that is, the supply molar ratio of Mo and Bi is the molar ratio of Mo and Bi in the bulk composition formula (1) of the metal oxide to be produced. That is, it matches a / 12.

In the preparation of the slurry in the conventional method for producing a metal oxide catalyst, the Mo-containing liquid and the Bi-containing liquid are mixed by adding the other liquid to either one liquid. However, in this method, the concentration of the component to be added is small immediately after the start of mixing, and gradually increases as the mixing progresses. In this way, although the intended atomic ratio is achieved when all the two liquids have been added, a significant imbalance is likely to occur between the component concentration on the added side and the component concentration on the adding side in the middle of the addition. .. According to the studies of the present inventors, the imbalance of Bi and Mo concentrations in the mixed solution at the time of preparing the slurry reduces the uniformity of the surface composition of the catalyst produced from the slurry thus prepared later. It turned out to be one of the causes.
On the other hand, in the first method, since the two liquids are supplied to the confluence portion at the same time, the imbalance of the component concentrations in the mixed liquid as described above is small.
In particular, when the Mo-containing liquid and the Bi-containing liquid are supplied within a specific ratio range, the catalyst composition produced by the atomic ratio of Mo and Bi in the mixed liquid is produced at any stage of the step of mixing the two. The slurry will be formed in a state close to the atomic ratio of. By preparing the slurry in such a state, the composition ratio of Mo and Bi on the surface of the finally produced catalyst particles can be made more uniform.

In the first production method, after performing the steps (i) and (ii) for each batch and storing the entire amount of one batch of the MoBi-containing liquid obtained in the step (ii) in the step (v), or ( In the case of adopting the batch processing method of sending to the (iii) step after storing in the (v) step after passing through the iv) step, the supply ratio (mB / mA) is the mass ratio (MB / MA) as described above. ) Is preferably 0.5 to 1.5 times. However, it is not always necessary to bring the total amount of the two liquids into contact in the range of 0.5 times to 1.5 times, and the supply of a part of the Mo-containing liquid and the Bi-containing liquid may be outside the above range.
Specifically, 60% by mass or more of the total amount of the total supply amount of the Mo-containing liquid and the Bi-containing liquid per batch is supplied so that the supply ratio is 0.5 to 1.5 times the mass ratio. It is more preferable to supply 80% by mass or more so as to be 0.5 to 1.5 times, and 100% by mass (that is, over the entire step (ii)) is 0. It is particularly preferable to supply the mixture so as to be 5 times to 1.5 times.
This will be described with reference to the above-mentioned 100 parts by mass of Mo-containing liquid containing a raw material for Mo12 atoms and 50 parts by mass of a Bi-containing liquid containing a raw material for 1 Bi atom. In this case, the total amount of the total supply amount of the Mo-containing liquid and the Bi-containing liquid is 150 parts by mass, and 60% by mass or more thereof corresponds to 90 parts by mass or more.
That is, supplying 60% by mass or more of the total amount of the total supply amount of the two liquids so that the supply ratio is 0.5 to 1.5 times the mass ratio means the supply amount per unit time (mass supply). Expressed as a ratio of (velocity), it corresponds to contacting 90 parts by mass or more of the total of the two liquids within the range of Mo-containing liquid: Bi-containing liquid = 100: 25 to 100: 75.

In the step (ii), the merging temperature at the time of merging the two liquids is preferably 5 ° C. to 98 ° C. 35 ° C to 98 ° C is more preferable, 35 ° C to 80 ° C is further preferable, and 35 ° C to 60 ° C is particularly preferable. When it is carried out at 35 ° C. to 60 ° C., catalyst particles having a more uniform surface composition can be produced. Here, the merging temperature means the liquid temperature of the portion where the two liquids are merging, and can be measured by a thermometer.

In the case of providing a step ((iv) step) of further mixing the MoBi-containing liquid after mixing the two liquids in the step (ii) to generate a MoBi-containing liquid (slurry) and before drying the MoBi-containing liquid. The method for further mixing the produced MoBi-containing liquid is not limited, and examples thereof include passing through a static mixer and stirring using a stirrer.
The stirring temperature is preferably about the same as the merging temperature when the two liquids are merged, and specifically, 35 ° C. to 80 ° C. is preferable.

In the present embodiment, the configuration of the apparatus used in the production of the catalyst is not limited, but for example, a first flow path for sending the Mo-containing liquid and a second flow path for sending the Bi-containing liquid. , And, it is preferable that the first flow path and the second flow path have a confluence portion where they meet.
The means for supplying the Mo-containing liquid and the Bi-containing liquid to the first and second flow paths is not limited, and for example, it is preferable to use a quantitative supply device. By using the fixed quantity supply device, the two liquids can be supplied in a more accurate ratio. The fixed-quantity supply device is not particularly limited, but a fixed-quantity liquid feeding pump is preferable.
The confluence portion where the two liquids merge is not particularly limited as long as the two liquids can merge, but for example, a pipe having a Y-shaped or T-shaped shape may be used. The cross-sectional shape of the tube may be, for example, circular (cylindrical), and it is also preferable to provide a mechanism or an interpolation for promoting mixing of the MoBi-containing liquid inside. The angle at which the two liquids merge may be parallel, vertical, or opposite.

It is also preferable to provide a mixer for further mixing the generated MoBi-containing liquid downstream of the confluence. An example of a mixer is a stirrer with a stirrer. An example of such a device configuration is shown in FIG. It is also preferable that each of the above-mentioned devices and the like has a heat retaining and heating structure such as a hot water jacket so that the desired temperature can be obtained.
As another example of the mixer, a static mixer as shown in FIG. 2 (a pipe and a twisted plate fixed therein are the main members, and the fluid supplied into the pipe has a twisted surface. It is mixed by flowing along the line). An example of a static mixer is a static mixer (manufactured by Noritake Company Limited). As shown in FIG. 1, a stationary mixer and a stirring tank may be combined.

By drying the MoBi-containing liquid produced as described above (step (iii)), a catalyst containing a metal oxide having a bulk composition represented by the formula (1) can be formed.
The pH of the MoBi-containing liquid is preferably 3 or less before drying. It is more preferably 2 or less, still more preferably 1 or less. The pH can be adjusted by, for example, the amount of the acidic solution added to the raw material. When the pH is 3 or less, the increase in the viscosity of the MoBi-containing liquid can be suppressed, and the MoBi-containing liquid can be stably supplied to the (iii) drying step of the next step.

According to the first production method, since the slurry preparation step for forming the catalyst precursor can be performed entirely in liquid form, it can be said that it is extremely simple as compared with the method requiring drying, firing, pulverization, etc. for forming the catalyst precursor. ..

In the step (iii), the drying method is not limited, but it is preferable to spray-dry the MoBi-containing liquid described above to obtain dried particles. For spray drying, for example, when it is performed industrially, it is preferable to use a spray dryer.
In the spray drying step, first, the MoBi-containing liquid is sprayed. The spraying method is not particularly limited, and examples thereof include a centrifugal method, a two-fluid nozzle method, and a high-pressure nozzle method. In particular, the centrifugal method is preferable from the viewpoint of not causing the nozzle to be blocked.
The method for drying the droplets of the sprayed MoBi-containing liquid is not limited, but it is preferable that the droplets are dried by hot air in a spray dryer, for example. At that time, the hot air inlet temperature is preferably 180 ° C. to 250 ° C., and the hot air outlet temperature is preferably 100 ° C. to 150 ° C.
At the time of spraying, it is preferable to adjust the spraying device so that the spray particle size is in a desired range according to the target particle size of the catalyst. For example, when the catalyst is used for the fluidized bed reaction, the average particle size of the catalyst is preferably about 25 to 180 μm. Therefore, the rotation speed of the atomizer is appropriately selected so that the average particle size is in this range. .. Generally, the higher the atomizer rotation speed, the smaller the average particle size.

In the present embodiment, it is preferable to include a firing step of obtaining a catalyst by firing the dried product (dried particles) obtained in the above drying step. The firing method is not particularly limited, and examples thereof include static firing, fluid firing, rotary furnace firing, and the like. From the viewpoint of uniform firing, rotary furnace firing using a rotary kiln is preferable.
When the dry particles contain nitric acid, it is preferable to perform denitration treatment before firing. The denitration treatment is preferably carried out at 150 to 450 ° C. for 1.5 to 3 hours. Firing can be performed in an air atmosphere.
The firing temperature is preferably 550 to 650 ° C. When the calcination temperature is 550 ° C. or higher, the crystal growth tends to proceed sufficiently, and the selectivity of the obtained catalyst acrylonitrile tends to be further improved. Further, when the firing temperature is 650 ° C. or lower, the surface area of the obtained catalyst is increased, and the reaction activity of propylene tends to be further improved. The firing time is preferably 1 hr to 24 hr, more preferably 2 hr to 20 hr. Conditions such as firing temperature and firing time are appropriately selected so that the desired catalyst physical characteristics and reaction performance can be obtained.

In the present embodiment, the above-mentioned MoBi-containing liquid preparation steps ((i) and (ii) steps),, if necessary, a mixing step ((iv) step) and a storage step ((v) step), and a drying step. ((Iii) step) Further, by performing the firing step as a series of treatments as necessary, a catalyst having stable catalyst physical properties and catalytic performance can be rapidly and continuously produced.

In the present embodiment, when both the (iv) step and the (v) step are performed between the (iii) step and the (iii) step, the (v) step is performed after the (iv) step, or the (iv) step is performed. It is preferable that the step and the step (v) are performed at the same time (that is, the MoBi-containing liquid is stored under stirring).
Further, when a series of processes of (i), (ii) and (v) or steps (i), (ii), (iv) and (v) are performed by a batch processing method, step (v). The storage amount in (ii) is preferably the total amount of the MoBi-containing liquid obtained in the step (ii). By temporarily storing the entire amount of the MoBi-containing liquid prepared in the step (ii) and then supplying it to the drying step ((iii) step), the supply amounts of the Mo-containing liquid and the Bo-containing liquid vary in the step (ii). Even in this case, the atomic number ratio of Mo and Bi in the MoBi-containing liquid supplied to the step (iii) can be made equal to the atomic number ratio of both in the formula (1), and the composition of the obtained catalyst particles can be adjusted. It can be closer to the purpose.
The storage container is not limited, and for example, a storage container having a stirring function can be used, and the step (v) and the step (iv) can be performed at the same time.

The first production method is a preferable method because it does not depend on the production scale, but the catalyst of the present embodiment may be produced by a method other than the first production method.
For example, in the preparation of a raw material slurry, even when a stirring and mixing tank is used and a batch mixing of a Mo-containing liquid and a Bi-containing liquid in which the other liquid is added to one of the liquids is adopted, 50 kg or more per batch is adopted. The metal oxide of the above is produced, and the time required for charging the liquid to be charged is set to 8 minutes or less, preferably 4 minutes or less, thereby promoting uniform mixing of the two liquids and using the catalyst of the present embodiment. Can be obtained (second manufacturing method).
This is due to the synergistic effect of increasing the amount of Mo / Bi-containing liquid to be charged, increasing the mass of the charged liquid, increasing the collision energy with the liquid to be charged, and processing in a short time. This is probably because uniform mixing of the slurry is achieved.

[Manufacturing method of acrylonitrile]
The method for producing acrylonitrile according to the present embodiment uses the catalyst of the present embodiment. That is, acrylonitrile can be produced by subjecting propylene, molecular oxygen, and ammonia to a fluidized bed ammoxidation reaction in the presence of the catalyst of the present embodiment.
The method for producing acrylonitrile according to the present embodiment may be carried out, for example, in a commonly used fluidized bed reactor. The raw materials propylene and ammonia do not necessarily have to be of high purity, and industrial grade ones can be used. Further, as the molecular oxygen source, it is usually preferable to use air, but a gas having an increased oxygen concentration such as by mixing oxygen with air can also be used.

When the molecular oxygen source in the method for producing acrylonitrile according to the present embodiment is air, the composition of the raw material gas (molar ratio of ammonia and air to propylene) is a ratio of propylene / ammonia / air, preferably 1 / ( It is in the range of 0.8 to 1.4) / (7 to 12), more preferably in the range of 1 / (0.9 to 1.3) / (8 to 11).

The reaction temperature in the method for producing acrylonitrile according to the present embodiment is preferably in the range of 350 to 550 ° C, more preferably in the range of 400 to 500 ° C. The reaction pressure is preferably in the range of normal pressure to 0.3 MPa. The contact time between the raw material gas and the catalyst is preferably 0.5 to 20 (sec · g / cc), more preferably 1 to 10 (sec · g / cc).

Hereinafter, the present embodiment will be described in more detail with reference to examples, but the present embodiment is not limited to these examples. The evaluation methods for various physical properties are as shown below.

[Production conditions and yield of acrylonitrile by ammoxidation reaction of propylene]
Acrylonitrile was produced by an ammoxidation reaction of propylene using the catalysts obtained in Examples and Comparative Examples. As the reaction tube used at that time, a Pyrex (registered trademark) glass tube having an inner diameter of 25 mm in which 16 10-mesh wire meshes were built in at 1 cm intervals was used.
The reaction was carried out by setting the catalyst amount to 50 cc, the reaction temperature to 430 ° C., and the reaction pressure to 0.17 MPa, and supplying a mixed gas of propylene / ammonia / air at a total gas flow rate of 250 to 450 cc / sec (NTP conversion). At that time, the content of propylene in the mixed gas is 9% by volume, and the molar ratio of propylene / ammonia / air is 1 / (0.7 to 1.4) / (8.0 to 13.5). The ammonia flow rate is adjusted so that the sulfuric acid intensity defined by the following formula is 20 ± 2 kg / T-AN, and the oxygen concentration of the reactor outlet gas is 0.2 ± 0.02% by volume. The air flow rate was changed as appropriate. Further, by changing the flow velocity of the entire mixed gas, the contact time defined by the following formula was changed, and the propylene conversion rate defined by the following formula was set to be 99.3 ± 0.2%.
The yield of acrylonitrile produced by the reaction was defined as the following formula.

[Evaluation of uniformity of composition on the surface of catalyst particles]
The uniformity of the composition of the particle surface of the catalyst in Examples and Comparative Examples was evaluated as follows, and expressed as the standard deviation of the particle surface composition.
SEM-EDX (Scattering Electron Microscopes-Energy Dispersive X-ray Spectroscopy: Energy Dispersive X-ray Spectroscopy) Composition Analyzer (SEM ... Hitachi, Model: SU-70, EDX ... Horiba, Model: A small amount of metal oxide particles (fired particles) were collected on a -max) sample table, and the equivalent diameter of the perfect circle (the diameter of the perfect circle with the same area) in the randomly selected particle image was the laser diffraction / scattering particle size. For 100 particles with an average particle size of ± 10 μm determined by a distribution measuring device (Laser diffraction / scattering type particle size distribution measuring device LA-300 manufactured by Horiba Seisakusho), Momol in a surface range of 10 μm × 10 μm on each particle surface. The concentration and the Bimol concentration were measured (magnification 1500 times, acceleration voltage 20 kV), and the ratio of the Bi concentration to the Mo concentration on the particle surface (Bi / Mo) was determined.
Next, 20 mg of the same catalyst powder was weighed, dissolved in hot aqua regia at 210 ° C., further diluted with ultrapure water to the measurement range, and subjected to ICP emission spectroscopic analysis (SPS3500DD, manufactured by Seiko Instruments Co., Ltd.). The concentration of each constituent element was measured, the bulk composition of the metal oxide contained in the catalyst was calculated, and the ratio of the Bi concentration to the Mo concentration of the metal oxide (Bi / Mo) _bulk was determined. In the catalysts 1 to 9 described later, the bulk composition of the metal oxide was in agreement with the theoretical value calculated from the raw material charge mass (the top 2 in the molar composition expressed based on the _{Mo 12 standard).} It was the same as the molar composition calculated from the charged mass up to the digit).
_{The value obtained by dividing the (Bi / Mo) surf} of each of the above 100 particles by this (Bi / Mo) _bulk is defined as Sk (k = 1 to 100), and the average value μ of 100 Sks is calculated and the formula is used. The standard deviation was calculated from (4).
Standard deviation = {((S ₁ − μ) ² + (S ₂ − μ) ² + ・ ・ ・ + (S ₁₀₀ − μ) ² ) / 100 [Number]} ^1/2 (4)
In the following examples and comparative examples, the more uniform the surface composition of the catalyst particles (that is, the smaller the standard deviation), the better the acrylonitrile yield (catalytic performance) in the reaction for producing acrylonitrile by the ammoxidation reaction of propylene. Was confirmed to indicate.

[Example 1]
[Manufacturing of catalyst 1]
The composition is supported on _{Mo 12 Bi 0.25 Fe 1.4 Ni 3.0} Co 5.8 Ce 0.40 Rb 0.12 O f and 60 wt% metal oxide prepared by adjusting the raw material charged mass so that 40 wt% silica catalyst, following Manufactured according to the procedure of.
Two types are mixed by mixing 666.7 g of an aqueous silica sol containing 30% by mass _{of SiO 2} having an average particle diameter of 12 nm for primary particles and 500 g of an aqueous silica sol containing 40% by mass _{of SiO 2 having an average particle diameter of 41 nm for primary particles.} A mixture of silica was obtained.
Next, 320 g of an 8 mass% oxalic acid aqueous solution was added to the mixed solution of the above silica sol being stirred to obtain a first mixed solution. Next, ammonium paramolybdate in 486.2g of water 870g of _{[(NH 4) 6 Mo 7 O} 24 · 4H 2 O ] were dissolved liquid was added to a mixture of the silica sol (Mo-containing solution. Thereafter, It is called "A1 solution"). The total amount was 2843 g.
Then, the nitric acid solution 400g of 16.6% strength by weight, of bismuth nitrate 28.09g _{[Bi (NO 3) 3 · 5H} 2 O ], iron nitrate [Fe (NO ₃₎ of 131.1g ₃ · 9H ₂ O ], nickel nitrate 202.9g _{[Ni (NO 3) 2 · 6H} 2 O ], cobalt nitrate 392.6g _{[Co (NO 3) 2 · 6H} 2 O ], cerium nitrate 39.62g [Ce (NO _{3) 3} · 6H ₂ O] were dissolved rubidium nitrate of 4.038g [RbNO _3] (Bi-containing solution. hereinafter referred to as "B1 liquid"). The total amount was 1198 g.

A container containing A1 liquid is piped (first) to one inlet 1 of an empty Y-shaped stainless steel cylindrical pipe (inner diameter 15 mm, length 30 mm) (confluence) via an A1 liquid fixed quantity liquid feed pump. It was connected by a channel). Further, the container containing the B1 liquid was connected to the other inlet 2 of the Y-shaped pipe by a pipe (second flow path) via a B1 liquid fixed-quantity liquid feed pump. The outlet of the Y-shaped tube was connected to a static mixer having a screw-type interior, and the outlet of the static mixer was connected to a slurry stirring tank having a stirrer by piping. A schematic diagram of the device is shown in FIG.
In the Y-shaped tube, the flow rate of A1 solution held at 40 ° C. was 284 (g / min) using the A1 solution metering pump, and the B1 solution held at 40 ° C. was 119 (g / min) using the B1 solution metering pump. ) At the same time, the two liquids were brought into contact with each other in the parallel direction (parallel flow) in the Y-tube and the stationary mixer. This operation was carried out for 10 minutes to prepare a MoBi-containing liquid as a slurry. During this period, the supply ratio of the B1 liquid [Bi-containing liquid] to the A1 liquid [Mo-containing liquid] was 119 (g / min) / 284 (g / min) = 0.42, and the total amount of the Bi-containing liquid with respect to the total amount of the Mo-containing liquid. The mass ratio of 1198 (g) / 2843 (g) = 0.42 was 1.0 times. At this supply ratio, all of the A1 solution and the B1 solution (100% by mass) were merged. The merging temperature during that period was 40 ° C.
The entire amount of this MoBi-containing liquid was stored in a slurry stirring tank provided downstream of the static mixer, and stirring was continued at 40 ° C. for 1 hour after the supply of the two liquids was completed. The pH of this MoBi-containing liquid was 1 or less and was in the form of a slurry before spray drying.
Next, this MoBi-containing liquid was spray-dried using a spray dryer (manufactured by Okawara Kakoki, model: OC-16) to obtain a dry powder. The hot air inlet temperature was 230 ° C. and the hot air outlet temperature was 120 ° C.
Next, the dried catalyst precursor was pre-baked at 320 ° C. for 2 hours in an air atmosphere using an electric furnace, and then main-fired at 600 ° C. for 2 hours in an air atmosphere to obtain a catalyst. (Catalyst 1).

The shape of the obtained catalyst 1 was a solid sphere, and the average particle size was 54 μm. The average particle size was measured using a laser diffraction / scattering particle size distribution measuring device LA-300 manufactured by HORIBA, Ltd. The average particle size of the catalyst in the following Examples and Comparative Examples was 52 μm to 55 μm.
The Mo concentration and Bi concentration on the surface of 100 particles of the catalyst 1 were measured by SEM-EDX, and the ratio (Bi / Mo) _surf of the Bi molar concentration to the Mo molar concentration was determined. Further, from the bulk composition of the metal oxide obtained above, (Bi / Mo) seeking _bulk, (Bi / Mo) _bulk at 100 particles of each (Bi / Mo) by dividing the _surf value S ₁ · ·・ S ₁₀₀ was calculated. Then, the average value (average value of S ₁ ... S ₁₀₀ ) μ was obtained, and the standard deviation value was obtained using the equation (4). In addition, acrylonitrile was produced by an ammoxidation reaction of propylene using the catalyst 1. These results are shown in Table 2.

[Example 2]
[Manufacturing of catalyst 2]
The composition is supported on _{Mo 12 Bi 0.39 Fe 1.60 Ni 7.0} Mg 0.77 Ce 0.63 Rb 0.17 O f and 60 wt% metal oxide prepared by adjusting the raw material charged mass so that 40 wt% silica catalyst, following Manufactured according to the procedure of.

First, 25.0 g of molybdenum dihydrate dissolved in 200 g of water was added to 1333 g of a silica sol containing 30% by mass _{of SiO 2} having an average particle diameter of 12 nm, and the mixture was dissolved in 873.5 g of water 485. ammonium paramolybdate of _{.9g [(NH 4) 6 Mo} 7 O 24 · 4H 2 O] was added under stirring to obtain a mixture containing molybdenum and silica. Hereinafter, this is referred to as A2 solution. The total amount of the A2 solution was 2917 g.
Next, 16.6% by weight nitric acid 396.7G, bismuth nitrate _{43.1g [Bi (NO 3) 3} · 5H 2 O], iron nitrate _{148.0g [Fe (NO 3) 3} · 9H 2 O], 464.7g of nickel nitrate _{[Ni (NO 3) 2 ·} 6H 2 O], magnesium nitrate of _{45.5g [Mg (NO 3) 2} · 6H 2 O], cerium nitrate 62.6 g [Ce ( _{NO 3) 3 · 6H 2 O} ], was dissolved rubidium nitrate of 5.89g [RbNO _3]. Hereinafter, this is referred to as B2 liquid. The total amount of B2 solution was 1166 g.

In the same manner as in Example 1, the A2 solution held at 40 ° C. was subjected to a flow rate of 291 (g / min), and the B2 solution held at 40 ° C. was subjected to a flow rate of 117 (g / min), which was the same as in Example 1. Contacted by method. This operation was carried out for 10 minutes to prepare a MoBi-containing liquid as a slurry. During this period, the supply ratio of the B2 liquid [Bi-containing liquid] to the A2 liquid [Mo-containing liquid] was 117 (g / min) / 291 (g / min) = 0.40, and the total amount of the Bi-containing liquid with respect to the total amount of the Mo-containing liquid. The mass ratio of 1166 (g) / 2917 (g) = 0.40 was 1.0 times. At this supply ratio, all of the A2 solution and the B2 solution (100% by mass) were merged. The merging temperature during that period was 40 ° C.
The entire amount of this MoBi-containing liquid was stored in a slurry stirring tank provided downstream of the static mixer, and stirring was continued at 40 ° C. for 1 hour after the supply of the two liquids was completed. The pH of this MoBi-containing liquid was 1 or less and was in the form of a slurry before spray drying.
Then, the MoBi-containing liquid was spray-dried in the same manner as in Example 1 to obtain a dry powder. The hot air inlet temperature was 230 ° C. and the hot air outlet temperature was 110 ° C.
Next, the dried catalyst precursor is held at 200 ° C. for 5 minutes in an air atmosphere, heated from 200 ° C. to 450 ° C. at 2.5 ° C./min, and held at 450 ° C. for 20 minutes. After the pre-baking, the air atmosphere was created and the main firing was performed at 580 ° C. for 2 hours to obtain a catalyst (catalyst 2).
Table 2 shows the standard deviation values of the catalyst 2 and the results of the ammoxidation reaction obtained in the same manner as in Example 1.

[Example 3]
The composition is supported on _{Mo 12 Bi 0.39 Fe 1.60 Co 4.30} Ni 3.45 Ce 0.68 Rb 0.16 O f and the metal oxide 58 wt% of the raw material charged mass was prepared adjusted to 42 wt% silica catalyst, following Manufactured according to the procedure of.

First, 25.0 g of molybdenum dihydrate dissolved in 200 g of water was added to 1400 g of a silica sol containing 30% by mass _{of SiO 2} having an average particle diameter of 12 nm, and 465 was dissolved in 836.85 g of water. ammonium paramolybdate of _{.5g [(NH 4) 6 Mo} 7 O 24 · 4H 2 O] was added under stirring to obtain a mixture containing molybdenum and silica. Hereinafter, this is referred to as A3 solution. The total amount of the A3 solution was 2927 g.
Then, 16.6 wt% of 36.1g of bismuth nitrate in nitric acid _{394.5g [Bi (NO 3) 3} · 5H 2 O], iron nitrate [Fe (NO ₃₎ of 141.6g ₃ · 9H ₂ O ], cobalt nitrate _{275.1g [Co (NO 3) 2} · 6H 2 O], 219.9g of nickel nitrate _{[Ni (NO 3) 2 ·} 6H 2 O], cerium nitrate 64.6 g [Ce (NO _{3) 3 · 6H 2 O]} , was dissolved rubidium nitrate of 5.33g [RbNO _3]. Hereinafter, this is referred to as B3 solution. The total amount of B3 solution was 1137 g.

In the same manner as in Example 1, the A3 solution held at 40 ° C. was subjected to a flow rate of 292 (g / min), and the B3 solution held at 40 ° C. was subjected to a flow rate of 115 (g / min), which was the same as in Example 1. Contacted by method. This operation was carried out for 10 minutes to prepare a MoBi-containing liquid as a slurry. During this period, the supply ratio of the B3 liquid [Bi-containing liquid] to the A3 liquid [Mo-containing liquid] was 115 (g / min) / 292 (g / min) = 0.39, and the total amount of the Bi-containing liquid with respect to the total amount of the Mo-containing liquid. The mass ratio of 1137 (g) / 2927 (g) = 0.39 was 1.0 times. At this supply ratio, all of the A3 solution and the B3 solution (100% by mass) were merged. The merging temperature during that period was 40 ° C.
The entire amount of this MoBi-containing liquid was stored in a slurry stirring tank provided downstream of the static mixer, and stirring was continued at 40 ° C. for 1 hour after the supply of the two liquids was completed. The pH of this MoBi-containing liquid was 1 or less and was in the form of a slurry before spray drying.
Then, the MoBi-containing liquid was spray-dried in the same manner as in Example 1 to obtain a dry powder. The hot air inlet temperature was 230 ° C. and the hot air outlet temperature was 110 ° C.
Next, the dried catalyst precursor is held at 200 ° C. for 5 minutes in an air atmosphere, heated from 200 ° C. to 450 ° C. at 2.5 ° C./min, and held at 450 ° C. for 20 minutes. After the pre-baking, the air atmosphere was created and the main firing was performed at 585 ° C. for 2 hours to obtain a catalyst (catalyst 3).
Table 2 shows the standard deviation values of the catalyst 3 and the results of the ammoxidation reaction obtained in the same manner as in Example 1.

[Example 4]
[Manufacturing of catalyst 4]
In the same manner as in Example 1, a Mo-containing liquid (same as A1 liquid; hereinafter referred to as "A4 liquid") and a Bi-containing liquid (same as B1 liquid; however, hereinafter referred to as "B4 liquid"). ) Was prepared. The total supply amount of the A4 solution and the B4 solution was the same as in Example 1, and therefore the mass ratio in this case was 0.42 as in Example 1.
A catalyst was obtained in the same manner as in Example 1 except that the supply ratio of the B4 solution to the A4 solution was varied between 0.8 times and 1.2 times the mass ratio of 0.42 described above (catalyst 4). ). All of the A4 solution and the B4 solution (100% by mass) were merged at a supply ratio in this range.
Specifically, it was done as follows. The A4 solution was simultaneously supplied to the Y-shaped tube at a flow rate of 302 (g / min) through the first flow path and the B4 solution at a flow rate of 102 (g / min) through the second flow path for 3 minutes. This supply ratio was 102 (g / min) / 302 (g / min) = 0.34, which was 0.8 times the above mass ratio of 0.42.
Next, the supply flow rates of the A4 solution and the B4 solution were changed, and the A4 solution was supplied at a flow rate of 284 (g / min) and the B4 solution was supplied at a flow rate of 120 (g / min) at the same time for 4 minutes. The supply ratio at this time was 120 (g / min) / 284 (g / min) = 0.42, which was 1.0 times the above mass ratio of 0.42.
Further, the supply flow rates of the A4 solution and the B4 solution were changed, and the A4 solution was supplied at a flow rate of 268 (g / min) and the B4 solution was supplied at a flow rate of 136 (g / min) at the same time for 3 minutes. The supply ratio at this time was 136 (g / min) / 268 (g / min) = 0.51, which was 1.2 times the above mass ratio of 0.42.
At any stage, the confluence temperature of the A4 solution and the B4 solution was 40 ° C. The MoBi-containing liquid produced had a pH of 1 or less and was in the form of a slurry before spray drying.
Table 2 shows the standard deviation values of the catalyst 4 and the results of the ammoxidation reaction obtained in the same manner as in Example 1.

[Example 5]
[Manufacturing of catalyst 5]
In the same manner as in Example 1, a Mo-containing liquid (same as A1 liquid; hereinafter referred to as "A5 liquid") and a Bi-containing liquid (same as B1 liquid; however, hereinafter referred to as "B5 liquid"). ) Was prepared. The total supply amount of the A5 solution and the B5 solution was the same as in Example 1, and therefore the mass ratio in this case was 0.42 as in Example 1.
A catalyst was obtained in the same manner as in Example 1 except that the supply ratio of the B5 solution to the A5 solution was varied between 0.5 times and 1.5 times the mass ratio of 0.42 described above (catalyst 5). ). All of the A5 solution and the B5 solution (100% by mass) were brought into contact with each other at a supply ratio in this range.
Specifically, it was done as follows. The A5 solution was simultaneously supplied to the Y-shaped tube at 334 (g / min) and the B5 solution was supplied at 70 (g / min) for 3 minutes. This supply ratio was 70 (g / min) / 334 (g / min) = 0.21, which was 0.5 times the above mass ratio of 0.42.
Next, the supply flow rates of the A5 solution and the B5 solution were changed, and the A5 solution was simultaneously supplied at 284 (g / min) and the B5 solution was supplied at 120 (g / min) for 5 minutes. This supply ratio was 120 (g / min) / 284 (g / min) = 0.42, which was 1.0 times the above mass ratio of 0.42.
Further, the supply flow rates of the A5 solution and the B5 solution were changed, and the A5 solution was supplied at 248 (g / min) and the B5 solution was simultaneously supplied at 156 (g / min) for 2 minutes. This supply ratio was 156 (g / min) / 248 (g / min) = 0.63, which was 1.5 times the above mass ratio of 0.42. At any stage, the confluence temperature of the A5 solution and the B5 solution was 40 ° C. The MoBi-containing liquid produced had a pH of 1 or less and was liquid before spray drying.
Table 2 shows the standard deviation values of the catalyst 5 and the results of the ammoxidation reaction obtained in the same manner as in Example 1.

[Example 6]
[Manufacturing of catalyst 6]
After mixing the Mo-containing liquid and the Bi-containing liquid with the Y-shaped tube and the static mixer, the catalyst was prepared in the same manner as in Example 1 except that the liquid was not temporarily stored in the slurry stirring tank but was directly sent to the spray dryer. Obtained (catalyst 6). The merging temperature was 40 ° C. The MoBi-containing liquid produced had a pH of 1 or less and was in the form of a slurry before spray drying.
Table 2 shows the standard deviation values of the catalyst 6 and the results of the ammoxidation reaction obtained in the same manner as in Example 1.

[Example 7]
[Manufacturing of catalyst 7]
In the same manner as in Example 1, Mo-containing liquid (same as A1 liquid; hereinafter referred to as "A7 liquid") and Bi-containing liquid (same as B1 liquid; however, hereinafter referred to as "B7 liquid"). ) Was prepared. The mass ratio in this case was 0.42 as in Example 1.
The supply ratio of the B7 solution to the A7 solution corresponds to 60% by mass of the total supply amount of the Mo-containing solution and the Bi-containing solution, which is 0.5 to 1.5 times the above mass ratio of 0.36. It was done so as to be within the range. The remaining 40% by mass was adjusted to be out of the range of 0.5 to 1.5 times. Other than that, a catalyst was obtained in the same manner as in Example 1 (catalyst 7).

Specifically, it was done as follows.
The A7 solution was simultaneously supplied to the Y-shaped tube at a flow rate of 334 (g / min) and the B7 solution was supplied at a flow rate of 70 (g / min) through the pipes, and the supply was continued for 2 minutes. The supply ratio at this time was 70 (g / min) / 334 (g / min) = 0.21, which was 0.5 times the above mass ratio of 0.42.
Next, the supply flow rates of the A7 solution and the B7 solution were changed, and the A7 solution was supplied at a flow rate of 229 (g / min) and the B7 solution was simultaneously supplied at a flow rate of 192 (g / min) for 2 minutes. The supply ratio at this time was 192 (g / min) / 229 (g / min) = 0.84, which was 2.0 times the above mass ratio of 0.42.
Further, the supply flow rates of the A7 solution and the B7 solution were changed, and the A7 solution was supplied at a flow rate of 284 (g / min) and the B7 solution was supplied at a flow rate of 119 (g / min) at the same time for 2 minutes. The supply ratio at this time was 119 (g / min) / 284 (g / min) = 0.42, which was 1.0 times the above mass ratio of 0.42.
Subsequently, the supply flow rates of the A7 solution and the B7 solution were changed, and the A7 solution was supplied at a flow rate of 356 (g / min) and the B7 solution was simultaneously supplied at a flow rate of 45 (g / min) for 2 minutes. The supply ratio at this time was 45 (g / min) / 356 (g / min) = 0.13, which was 0.3 times the above mass ratio of 0.42.
Finally, the supply flow rates of the A7 solution and the B7 solution were changed, and the A7 solution was supplied at a flow rate of 248 (g / min) and the B7 solution was simultaneously supplied at a flow rate of 156 (g / min) for 2 minutes. The supply ratio at this time was 156 (g / min) / 248 (g / min) = 0.63, which was 1.5 times the above mass ratio of 0.42.
At any stage, the confluence temperature of the A7 solution and the B7 solution was 40 ° C.

After that, a catalyst was obtained in the same manner as in Example 1 (catalyst 7). The pH of this MoBi-containing liquid was 1 or less and was in the form of a slurry before spray drying.
Table 2 shows the standard deviation values of the catalyst 7 and the results of the ammoxidation reaction obtained in the same manner as in Example 1.

[Comparative Example 1]
[Manufacturing of catalyst 8]
Mo-containing liquid (same as A1 liquid; hereinafter referred to as "A8 liquid") and Bi-containing liquid (same as B1 liquid. However, hereinafter referred to as "B8 liquid") in the same manner as in Example 1. .) Was prepared.
A MoBi-containing liquid was prepared by adding the B8 liquid kept at 40 ° C. to the A8 liquid kept at 40 ° C. while stirring. A fixed-quantity liquid feed pump was used for charging.
Specifically, 1198 g of B8 solution was supplied to the total amount of 2843 g of A8 solution at a flow rate of 599 (g / min). The generated MoBi-containing liquid was further stirred at 40 ° C. for 1 hour. The pH of this MoBi-containing liquid was 1 or less and was in the form of a slurry before spray drying.
After that, a catalyst was obtained in the same manner as in Example 1 (catalyst 8).
Table 2 shows the standard deviation values of the catalyst 8 and the results of the ammoxidation reaction obtained in the same manner as in Example 1.

[Comparative Example 2]
[Manufacturing of catalyst 9]
Mo-containing liquid (same as A1 liquid, hereinafter referred to as "A9 liquid") and Bi-containing liquid (same as B1 liquid. However, hereinafter referred to as "B9 liquid") in the same manner as in Example 1. .) Was prepared.
A MoBi-containing liquid was prepared by adding the A9 liquid kept at 40 ° C. to the B9 liquid kept at 40 ° C. while stirring. A fixed-quantity liquid feed pump was used for charging.
Specifically, 2843 g of A9 solution was supplied to the total amount of 1198 g of B9 solution at a flow rate of 1422 (g / min). The generated MoBi-containing liquid was further stirred at 40 ° C. for 1 hour. The pH of this MoBi-containing liquid was 1 or less and was in the form of a slurry before spray drying.
After that, a catalyst was obtained in the same manner as in Example 1 (catalyst 9).
Table 2 shows the standard deviation values of the catalyst 9 and the results of the ammoxidation reaction obtained in the same manner as in Example 1.

Table 1 shows the bulk composition of the metal oxides contained in the catalysts obtained in Examples and Comparative Examples, and Table 2 shows the standard deviations _{of (Bi / Mo) surf} / (Bi / Mo) _{bulk on the surface of the catalyst particles.} Further, Table 2 also shows the production conditions of each catalyst and the yield when acrylonitrile was produced using each catalyst.
The bulk composition of the metal oxides contained in the catalysts obtained in Examples 1, 4 to 7 and Comparative Examples 1 and 2 is the same.
In Examples 1 to 7, the catalyst was produced using the MoBi-containing liquid prepared by merging the Mo-containing liquid and the Bi-containing liquid supplied to the first and second flow paths at the confluence, respectively, on the surface of the catalyst particles. A catalyst having a uniform composition ratio of Mo and Bi could be continuously produced. Further, when the catalysts produced in these examples were used, acrylonitrile could be produced in a high yield.
On the other hand, in Comparative Example 1 in which the Bi-containing liquid was added to the Mo-containing liquid (total amount) and Comparative Example 2 in which the Mo-containing liquid was added to the Bi-containing liquid (total amount), the surface of the obtained catalyst particles was obtained. The uniformity of the composition ratio of Mo and Bi was low. Moreover, when the catalysts obtained in Comparative Examples 1 and 2 were used, the yield of acrylonitrile was also low.

※１；Ｍｏ含有液とＢｉ含有液の全供給量の６０質量％を、供給比率が質量比率の０．５倍〜１．５倍の範囲内で行い、残りの４０質量％をそれ以外の範囲の供給比率で行った。

* 1: 60% by mass of the total supply amount of Mo-containing liquid and Bi-containing liquid is performed within the range of 0.5 to 1.5 times the mass ratio, and the remaining 40% by mass is other than that. The supply ratio was in the range.

The catalyst of the present invention can be used in the process of producing acrylonitrile from propylene.
Further, the method for producing a catalyst of the present invention can be suitably adopted for producing an ammoxidation reaction catalyst.

Claims (9)

A catalyst for producing acrylonitrile composed of particles containing a metal oxide having a bulk composition represented by the following formula (1).
The standard deviation of the value obtained by dividing the ratio of the Bi-molar concentration to the Mo-molar concentration on the surface of the catalyst particles by the ratio of the Bi-molar concentration to the Mo-molar concentration of the metal oxide bulk is 0.2 or less.
Catalyst for acrylonitrile production.
_{Mo 12 Bi a Fe b X c} Y d Z e O f (1)
(In formula (1), X is one or more elements selected from the group consisting of nickel, cobalt, magnesium, calcium, zinc, strontium and barium, and Y is cerium, chromium, lantern, neodymium, ittrium, placeodium, and samarium. , One or more elements selected from the group consisting of aluminum, gallium and indium, Z represents one or more elements selected from the group consisting of potassium, rubidium and strontium, and a, b, c, d and e are. 0.1 ≦ a ≦ 2.0, 0.1 ≦ b ≦ 3.0, 0.1 ≦ c ≦ 10.0, 0.1 ≦ d ≦ 3.0, and 0.01 ≦ e ≦ 2, respectively. Satisfying .0, f is the number of oxygen atoms required to satisfy the valence requirements of the other existing elements.) The catalyst for producing acrylonitrile according to claim 1, wherein the particles further contain silica. A method for producing a catalyst containing a metal oxide having a bulk composition represented by the following formula (1).
(I) A step of preparing a Mo-containing liquid containing at least Mo and a Bi-containing liquid containing at least Bi.
(Ii) The Mo-containing liquid is continuously supplied to the first flow path, the Bi-containing liquid is continuously supplied to the second flow path, and the first flow path and the second flow path To obtain a MoBi-containing liquid by mixing the Mo-containing liquid and the Bi-containing liquid by merging the Mo-containing liquid and the Bi-containing liquid downstream from the respective supply points, and (iii) the MoBi. The process of drying the contained liquid,
Including methods.
_{Mo 12 Bi a Fe b X c} Y d Z e O f (1)
(In formula (1), X is one or more elements selected from the group consisting of nickel, cobalt, magnesium, calcium, zinc, strontium and barium, and Y is cerium, chromium, lantern, neodymium, ittrium, placeodium, and samarium. , One or more elements selected from the group consisting of aluminum, gallium and indium, Z represents one or more elements selected from the group consisting of potassium, rubidium and strontium, and a, b, c, d and e are. 0.1 ≦ a ≦ 2.0, 0.1 ≦ b ≦ 3.0, 0.1 ≦ c ≦ 10.0, 0.1 ≦ d ≦ 3.0, and 0.01 ≦ e ≦ 2, respectively. Satisfying .0, f is the number of oxygen atoms required to satisfy the valence requirements of the other existing elements.) Between the step (iii) and the step (iii), further
(Iv) The method for producing a catalyst according to claim 3, further comprising a step of further mixing the MoBi-containing liquid. Between the step (iii) and the step (iii), further
(V) The method for producing a catalyst according to claim 3 or 4, which comprises a step of storing the MoBi-containing liquid. A series of processes of the steps (i), (ii) and (v) are performed by a batch processing method, and the entire amount of the MoBi-containing liquid obtained in the step (ii) for one batch is stored in the step (v). , The method for producing a catalyst according to claim 5.
In the step (ii), the mass supply rates of the Mo-containing liquid and the Bi-containing liquid to the first flow path or the second flow path are set to mA (g / min) and mb (g / g, respectively). When it is set to min), 60% by mass or more of the total amount of the total supply amounts MA (g) and MB (g) per batch of the Mo-containing liquid and the Bi-containing liquid satisfies the formula (2). A method of manufacturing a catalyst to be supplied to.
(MB / mA) / (MB / MA) = 0.5 to 1.5 (2) The method for producing a catalyst according to claim 3 or 4, wherein the MoBi-containing liquid is continuously supplied to the step (iii). In the step (ii), the molar supply rates of the Mo-containing liquid and the Bi-containing liquid to the first flow path or the second flow path are set to mα (mol / min) and mβ (mol / min), respectively. When
The Mo-containing liquid and the Bi-containing liquid are supplied so as to satisfy the formula (3).
The method for producing a catalyst according to claim 3, 4, or 7.
(Mβ / mα) / (a / 12) = 0.8 to 1.2 (3) A method for producing acrylonitrile, which comprises a step of reacting propylene, molecular oxygen, and ammonia in the presence of the catalyst according to claim 1 or 2.

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