Method for manufacturing molybdenum trioxide powder

Abstract

A method for manufacturing molybdenum trioxide powder is provided, which can reduce material costs and decrease the environmental impact and waste costs associated with the disposal of byproducts generated during roasting. The manufacturing method includes: a first roasting step of roasting a first raw material mixture comprising a molybdenum oxide precursor compound and metal compound particles other than molybdenum compounds in a sagger; a first cooling step of generating molybdenum trioxide powder; a first crushing step of crushing a residue in the sagger containing metal oxides derived from the aforementioned metal compound particles to form first crushed particles; a second roasting step of roasting a second raw material mixture comprising a molybdenum oxide precursor compound and the first crushed particles in a sagger; a second cooling step of generating molybdenum trioxide powder; and a second crushing step of crushing a residue in the sagger containing metal oxides derived from the first crushed particles to form second crushed particles.

Description

Technical Field

[0001] This invention relates to a method for manufacturing molybdenum trioxide powder. Background Technology

[0002] Previously, molybdenum disulfide (MoS2) and other molybdenum sulfides were widely used as lubricants, steel additives, and raw materials for molybdates. One method for manufacturing molybdenum sulfides is using molybdenum trioxide powder as a precursor.

[0003] Previously, one method for manufacturing molybdenum trioxide powder was to vaporize a molybdenum oxide precursor compound to form molybdenum trioxide vapor and then cool the molybdenum trioxide vapor.

[0004] For example, Patent Document 1 proposes a method for manufacturing molybdenum trioxide powder, which involves calcining a mixture of raw materials containing a molybdenum oxide precursor compound and a metal compound other than the molybdenum oxide precursor compound, thereby vaporizing the molybdenum oxide precursor compound to form molybdenum trioxide vapor.

[0005] Furthermore, Patent Document 1 describes a technique in which aluminum hydroxide and molybdenum trioxide are mixed, placed in a sagger, and calcined at 1100°C, with the molybdenum trioxide recovered using a dust collector. Moreover, Patent Document 1 describes the removal of aluminum oxide from the sagger after calcination.

[0006] Existing technical documents

[0007] Patent documents

[0008] Patent Document 1: International Publication No. 2022 / 202757 Summary of the Invention

[0009] The problem the invention aims to solve

[0010] However, when manufacturing molybdenum trioxide powder using a method that involves calcining a mixture of raw materials containing aluminum hydroxide and molybdenum trioxide, a large amount of aluminum hydroxide is required. Therefore, it is necessary to reduce the amount of aluminum hydroxide used and lower material costs.

[0011] Furthermore, when manufacturing molybdenum trioxide powder using the above method, aluminum hydroxide is converted into alumina as a byproduct due to calcination. Therefore, when manufacturing molybdenum trioxide powder using the above method, it is necessary to discard the alumina as a byproduct, and it is required to reduce the environmental impact and disposal costs associated with alumina disposal.

[0012] To address the aforementioned issues, it is considered to use only molybdenum trioxide as the material, without using aluminum hydroxide as a byproduct. However, the aluminum hydroxide contained in the raw material mixture has the following functions: maintaining the molten and liquefied molybdenum trioxide during calcination of the raw material mixture in the crucible; and reducing the contact area between the liquefied molybdenum trioxide and the crucible, thereby protecting the crucible.

[0013] Therefore, for example, using only molybdenum trioxide as a raw material can lead to the following undesirable situations: the molybdenum trioxide, liquefied during calcination, leaks out of the crucible; or the liquefied molybdenum trioxide comes into contact with the crucible, significantly corroding it and causing it to deteriorate. Therefore, it is preferable to include a sufficient amount of aluminum hydroxide in the raw material mixture along with the molybdenum trioxide. Consequently, using only molybdenum trioxide as a raw material is quite difficult.

[0014] The present invention was made in view of the above-mentioned problems, and its object is to provide a method for manufacturing molybdenum trioxide powder that can reduce the environmental burden and waste costs associated with the disposal of by-products generated during roasting while reducing material costs.

[0015] Solution for solving the problem

[0016] In order to solve the above-mentioned technical problems and reduce the environmental burden and waste costs associated with the disposal of by-products generated by roasting while reducing material costs, the inventors have conducted in-depth research on materials mixed with molybdenum trioxide in raw material mixtures and by-products generated by roasting the raw material mixtures, as shown below.

[0017] That is, when manufacturing molybdenum trioxide powder by calcining a mixture of raw materials containing aluminum hydroxide and molybdenum trioxide, it is considered that the aluminum oxide residue remaining in the calcined crucible can be reused as material for molybdenum trioxide powder.

[0018] However, the residue remaining in the sagger after firing is in block form, so it cannot fully achieve the functions of retaining molten and liquefied molybdenum trioxide and reducing the contact area between liquefied molybdenum trioxide and the sagger.

[0019] Therefore, the inventors crushed the lumpy residue containing alumina remaining in the sagger to produce alumina particles. The obtained alumina particles were then loaded into the sagger along with a molybdenum oxide precursor compound and calcined. As a result, it was found that the alumina particles could effectively suppress the leakage of liquefied molybdenum trioxide from the sagger during calcination, or effectively suppress the deterioration of the sagger caused by liquefied molybdenum trioxide.

[0020] That is, the inventors have discovered that by crushing the blocky alumina that is generated as a byproduct into alumina particles, it can be reused as a material in the manufacture of molybdenum trioxide powder.

[0021] Furthermore, the inventors conducted repeated research, confirmed (a) and (b) shown below, and conceived of the present invention.

[0022] (a) Even when a mixture of raw materials containing both molybdenum oxide precursor compounds and metal compound particles other than molybdenum compounds such as aluminum hydroxide, magnesium aluminate, titanium oxide, iron oxide, zinc oxide, and silicon dioxide is placed in a sagger for roasting, lumpy residues will be generated in the sagger after roasting.

[0023] (b) By crushing the blocky residue generated in (a) above into particles, and then loading them together with the molybdenum oxide precursor compound into a sagger for calcination, the leakage of molybdenum trioxide liquefied during calcination from the sagger or the deterioration of the sagger due to liquefied molybdenum trioxide can be effectively suppressed, just as when metal oxide containing alumina particles is loaded into a sagger for calcination.

[0024] The present invention provides the following means.

[0025] [1] A method for manufacturing molybdenum trioxide powder, comprising the following steps:

[0026] In the first roasting process, a first raw material mixture containing a molybdenum oxide precursor compound and metal compound particles other than molybdenum compounds is loaded into a sagger and roasted to vaporize the molybdenum oxide precursor compound into molybdenum trioxide vapor.

[0027] The first cooling step generates molybdenum trioxide powder by cooling the molybdenum trioxide vapor generated in the first calcination step.

[0028] The first crushing process involves crushing the residue containing metal oxides derived from the metal compound particles remaining in the sagger after the first roasting process to produce the first crushed particles.

[0029] In the second roasting process, the second raw material mixture containing the molybdenum oxide precursor compound and the first crushed particles is loaded into a sagger and roasted to vaporize the molybdenum oxide precursor compound and form molybdenum trioxide vapor.

[0030] The second cooling step generates molybdenum trioxide powder by cooling the molybdenum trioxide vapor generated in the second calcination step; and,

[0031] The second crushing process involves crushing the residue containing oxides of metals derived from the first crushed particles remaining in the sagger after the second roasting process to produce the second crushed particles.

[0032] [2] According to the method for manufacturing molybdenum trioxide powder described in [1], the average particle size of the first crushed particle and the second crushed particle is less than 1 mm.

[0033] [3] The method for manufacturing molybdenum trioxide powder according to [1] or [2], wherein the metal compound particles are selected from one or more of alumina particles, magnesium aluminate particles, titanium oxide particles, iron oxide particles, zinc oxide particles, and silicon dioxide particles.

[0034] [4] According to the method for manufacturing molybdenum trioxide powder described in [3], wherein the first raw material mixture contains only the molybdenum oxide precursor compound and the metal compound particles, and in the first calcination step, calcination is carried out at a temperature of 800°C or higher and 1200°C or lower.

[0035] The second raw material mixture contains only the molybdenum oxide precursor compound and the first crushed particles. In the second roasting process, the roasting is carried out at a temperature of 800°C or higher and 1200°C or lower.

[0036] [5] According to the method for manufacturing molybdenum trioxide powder as described in [3] or [4], wherein the first raw material mixture contains, relative to 100% by mass of the molybdenum oxide precursor compound, at least 50% by mass and less than 200% by mass of the aforementioned metal compound particles.

[0037] The second raw material mixture contains, relative to 100% by mass of the molybdenum oxide precursor compound, 50% by mass and less than 200% by mass of the first crushed particles.

[0038] [6] The method for manufacturing molybdenum trioxide powder according to any one of [1] to [5], wherein, in the first cooling step and the second cooling step, molybdenum trioxide powder with an average particle size of 5 nm or more and 100 nm or less is generated.

[0039] [7] The method for manufacturing molybdenum trioxide powder according to any one of [1] to [6], wherein, in the first cooling step and the second cooling step described above, a powder with a specific surface area of ​​10 m² as measured by the BET method is generated. 2 / g or more and 500m 2 Molybdenum trioxide powder with a concentration of less than / g.

[0040] [8] A method for manufacturing molybdenum trioxide powder according to any one of [1] to [7], wherein molybdenum trioxide powder containing a β crystal structure is generated in the first cooling step and the second cooling step described above.

[0041] The effects of the invention

[0042] In the method for manufacturing molybdenum trioxide powder of the present invention, in the first calcination step, metal compound particles other than molybdenum compound are used together with the molybdenum oxide precursor compound; in the first crushing step, the residue containing metal oxides derived from the metal compound particles remaining in the calcined sagger is crushed to produce the first crushed particles; and in the second calcination step, the first crushed particles are used together with the molybdenum oxide precursor compound.

[0043] Therefore, in the method for manufacturing molybdenum trioxide powder of the present invention, the residue of metal oxide containing metal compound particles other than molybdenum compound used in the first calcination step is crushed in the first crushing step to form first crushed particles, which are then reused as materials in the second calcination step.

[0044] Therefore, in the method for manufacturing molybdenum trioxide powder of the present invention, material costs can be reduced compared to, for example, not reusing the residues of metal oxides containing metal compound particles other than molybdenum compounds contained in the first raw material mixture.

[0045] Furthermore, in the method for manufacturing molybdenum trioxide powder of the present invention, the residue remaining in the calcined sagger is crushed to form first crushed particles, which are then reused in the second calcination process. Therefore, the residue remaining in the calcined sagger does not need to be discarded, and the environmental burden and disposal costs associated with discarding the residue remaining in the calcined sagger are avoided. Attached Figure Description

[0046] Figure 1 This is a schematic diagram of an example of a molybdenum trioxide powder manufacturing apparatus used to illustrate the method for manufacturing molybdenum trioxide powder in this embodiment.

[0047] Figure 2 This is a flowchart illustrating an example of a method for manufacturing molybdenum trioxide powder according to this embodiment.

[0048] Explanation of reference numerals in the attached figures

[0049] 1: Manufacturing equipment; 2: Roasting furnace; 3: Cooling piping; 4: Dust collection device; 5: Exhaust port; 6: Opening adjustment damper; 7: Observation window; 8: Exhaust system; 9: External cooling system; S11: First roasting process; S12: First cooling process; S13: First crushing process; S21: Second roasting process; S22: Second cooling process; S23: Second crushing process. Detailed Implementation

[0050] The method for manufacturing molybdenum trioxide powder according to this embodiment will be described in detail below with appropriate reference to the accompanying drawings. It should be noted that, for ease of understanding of the features of the present invention, the accompanying drawings used in the following description sometimes show enlarged features. Therefore, the size ratios of the constituent elements may differ from those in reality. The scope of the present invention is not limited to the embodiment described herein, and various modifications can be made without departing from the spirit of the invention. Furthermore, when multiple upper and lower limits are specified for a particular parameter, a suitable numerical range can be formed by combining any of these upper and lower limits.

[0051] [Apparatus for manufacturing molybdenum trioxide powder]

[0052] Figure 1 This is a schematic diagram of an example of a molybdenum trioxide powder manufacturing apparatus used to illustrate the method for manufacturing molybdenum trioxide powder in this embodiment.

[0053] Figure 1 The apparatus 1 for manufacturing molybdenum trioxide powder shown has a calcining furnace 2, cooling piping 3, dust collection device 4, and exhaust device 8.

[0054] Calcining furnace 2 calcines a mixture of raw materials containing molybdenum oxide precursor compounds, which is placed in a sagger (not shown), under specified calcination conditions, causing the molybdenum oxide precursor compounds to vaporize. Known calcining furnaces can be used as calcining furnace 2. For example... Figure 1 As shown, the top surface of the roasting furnace 2 is provided with an exhaust port 5.

[0055] Cooling piping 3 cools and pulverizes the molybdenum trioxide vapor formed by the gasification of the raw material mixture containing molybdenum oxide precursor compounds during roasting in the roasting furnace 2. For example... Figure 1 As shown, the cooling pipe 3 has a cross-shaped form when viewed from the side. The lower end of the cooling pipe 3 is connected to the exhaust port 5 of the roasting furnace 2. The upper end of the cooling pipe 3 is provided with an observation window 7 for observing the inside of the cooling pipe 3.

[0056] Additionally, an external gas intake port (not shown) is provided at the first horizontal end of cooling pipe 3. For example... Figure 1 As shown, the external gas intake port is equipped with an opening adjustment damper 6 for adjusting the opening degree of the external gas intake port.

[0057] A dust collection pipe is connected to the second horizontal end of cooling pipe 3. For example... Figure 1 As shown, the dust collection piping connects the cooling piping 3 and the dust collection device 4.

[0058] In the molybdenum trioxide powder manufacturing apparatus 1 of this embodiment, a known external cooling device that cools the cooling pipe 3 from its outer surface can be provided as needed. Figure 1(Referring to figure 9 in the figure).

[0059] The dust collection device 4 recovers the molybdenum trioxide powder that has been pulverized in the cooling pipe 3. For example, the dust collection device 4 can be a dust collection device that recovers the molybdenum trioxide powder contained in the gas supplied by the cooling pipe 3 by passing it through a filter such as a bag filter.

[0060] like Figure 1 As shown, the exhaust device 8 draws gas from the dust collection device 4 via a suction pipe. Known exhaust devices such as blowers can be used as the exhaust device 8.

[0061] Figure 1 In the molybdenum trioxide powder manufacturing apparatus 1 shown, the exhaust device 8 draws dust from the dust collection device 4 via a suction pipe. Furthermore, the cooling pipe 3 connected to the dust collection device 4 is also drawn through the dust collection pipe. This discharges the gas from the cooling pipe 3, and external gas is introduced into the cooling pipe 3 through the opening adjustment damper 6.

[0062] [Method for manufacturing molybdenum trioxide powder]

[0063] Then, as an example of the method for manufacturing molybdenum trioxide powder in this embodiment, the use of... Figure 1 The manufacturing apparatus 1 for molybdenum trioxide powder shown will be described in detail as an example of the manufacturing process of molybdenum trioxide powder.

[0064] Figure 2 This is a flowchart illustrating an example of a method for manufacturing molybdenum trioxide powder according to this embodiment. For example... Figure 2 As shown, the method for manufacturing molybdenum trioxide powder in this embodiment includes a first calcination step S11, a first cooling step S12, a first crushing step S13, a second calcination step S21, a second cooling step S22, and a second crushing step S23. Figure 2 As shown, the second roasting process S21, the second cooling process S22, and the second crushing process S23 can be repeated multiple times after the first crushing process S13, or they can be performed only once.

[0065] (First roasting step S11)

[0066] In the first roasting step S11, a first raw material mixture containing a molybdenum oxide precursor compound and metal compound particles other than the molybdenum compound is loaded into a sagger. Figure 1 The molybdenum oxide precursor compound is vaporized in the roasting furnace 2 shown, forming molybdenum trioxide vapor.

[0067] As a precursor compound of molybdenum oxide contained in the first raw material mixture, there are no particular restrictions as long as it can form molybdenum trioxide vapor through calcination.

[0068] The form of the molybdenum oxide precursor compound contained in the first raw material mixture is not particularly limited. For example, it can be in powder form such as molybdenum trioxide powder, or in liquid form such as an aqueous solution of ammonium molybdate. However, for better processability and energy efficiency, the molybdenum oxide precursor compound is preferably in powder form.

[0069] Examples of molybdenum oxide precursor compounds contained in the first raw material mixture include, for example, metallic molybdenum, molybdenum trioxide, molybdenum dioxide, molybdenum sulfide, ammonium molybdate, and phosphomolybdic acid (H3PMo). 12 O 40 ), molybdenum silicate (H4SiMo) 12 O 40 Aluminum molybdate, silicon molybdate, magnesium molybdate (MgMo) n O 3n+1 (n = 1~3)), sodium molybdate (Na2Mo) n O 3n+1 (n=1~3)), titanium molybdate, ferric molybdate, potassium molybdate (K2Mo) n O 3n+1 (n = 1~3)), zinc molybdate, boron molybdate, lithium molybdate (Li2Mo) n O 3n+1 (n=1~3)), cobalt molybdate, nickel molybdate, manganese molybdate, chromium molybdate, cesium molybdate, barium molybdate, strontium molybdate, yttrium molybdate, zirconium molybdate, copper molybdate, etc. These molybdenum oxide precursor compounds can be used alone or in combination of two or more.

[0070] From the viewpoint of easily controlling the purity, average particle size, and crystal structure of the manufactured molybdenum trioxide powder, the molybdenum oxide precursor compound contained in the first raw material mixture preferably includes molybdenum trioxide. In particular, commercially available α-crystal molybdenum trioxide is preferably used as the molybdenum oxide precursor compound. Furthermore, when ammonium molybdate is used as the molybdenum oxide precursor compound, it is converted into thermodynamically stable molybdenum trioxide through calcination, and thus the vaporized molybdenum oxide precursor compound forms molybdenum trioxide.

[0071] Examples of metal compound particles, other than molybdenum compounds, contained in the first raw material mixture include alumina particles, magnesium aluminate particles, titanium oxide particles, iron oxide particles, zinc oxide particles, and silicon dioxide particles. Only one type of metal compound particle other than molybdenum compounds may be used, or two or more may be used in combination.

[0072] The metal compound particles, excluding molybdenum compounds, contained in the first raw material mixture are preferably particles containing metal oxides that will not react with the molybdenum oxide precursor compound upon calcination. Examples of particles containing metal oxides that will not react with the molybdenum oxide precursor compound include, for example, one or more particles selected from alumina particles, magnesium aluminate particles, titanium oxide particles, iron oxide particles, zinc oxide particles, and silica particles. Among these metal oxide particles, particles selected from alumina particles, magnesium aluminate particles, and titanium oxide particles are preferred. This is because these metal oxide particles are readily available and inexpensive.

[0073] Regarding the metal compound particles other than molybdenum compounds contained in the first raw material mixture, particles containing alumina and / or particles containing magnesium aluminate are particularly preferred. This is because they have low reactivity with molybdenum oxide precursor compounds, are readily available, and inexpensive. Furthermore, when using alumina as the metal compound particles other than molybdenum compounds, those with an α-crystal structure are preferred.

[0074] The metal compound particles, excluding molybdenum compounds, contained in the first raw material mixture are preferably particles with an average particle size of 1 mm or less, more preferably particles with an average particle size of 1 μm or more but less than 100 μm. When the metal compound particles contained in the first raw material mixture have an average particle size of 1 mm or less, they more effectively retain the molten and liquefied molybdenum trioxide and reduce the contact area between the liquefied molybdenum trioxide and the crucible, thereby protecting the crucible. When the metal compound particles contained in the first raw material mixture have an average particle size of 1 μm or more, they become metal compound particles that can be easily manufactured, and are therefore preferred. More preferably, the metal compound particles contained in the first raw material mixture have an average particle size of 2 μm or more.

[0075] The first raw material mixture preferably contains 50% to 200% by mass of metal compound particles other than molybdenum compound relative to 100% by mass of the molybdenum oxide precursor compound. More preferably, it contains 100% to 200% by mass of metal compound particles other than molybdenum compound. When the first raw material mixture contains 50% or more of metal compound particles other than molybdenum compound, it more effectively utilizes the function of maintaining molten and liquefied molybdenum trioxide provided by the metal compound particles and the function of protecting the sagger by reducing the contact area between the liquefied molybdenum trioxide and the sagger. In addition, when the content of metal compound particles in the first raw material mixture is 200% by mass or less, less molybdenum trioxide vapor is generated by calcining the first raw material mixture, thereby not hindering the production rate of molybdenum trioxide powder, which is preferable.

[0076] The first raw material mixture is a substance comprising a molybdenum oxide precursor compound and metal compound particles other than the molybdenum compound. Preferably, it comprises only the molybdenum oxide precursor compound and one or more metal oxide particles selected from alumina particles, magnesium aluminate particles, titanium oxide particles, iron oxide particles, zinc oxide particles, and silica particles. When the first raw material mixture consists of a molybdenum oxide precursor compound and one or more of the aforementioned metal oxide particles, no intermediate is formed during the roasting process of the first raw material mixture. Therefore, it is not necessary to set the roasting temperature above the intermediate decomposition temperature; the roasting temperature can be set at a low temperature below 900°C.

[0077] In the first roasting process S11, the roasting conditions such as the heating rate, roasting temperature (maximum temperature), and roasting time (holding time at the maximum temperature) of the first raw material mixture can be appropriately determined according to the type and content of the molybdenum oxide precursor compound and metal compound particles other than molybdenum compounds contained in the first raw material mixture, as well as the amount of the first raw material mixture.

[0078] When the first raw material mixture contains only a molybdenum oxide precursor compound and one or more particles containing metal oxides selected from alumina particles, magnesium aluminate particles, titanium oxide particles, iron oxide particles, zinc oxide particles, and silica particles, the calcination temperature (maximum temperature) for calcining the first raw material mixture is preferably set to 800°C to 1200°C, more preferably to 850°C to 900°C. At a calcination temperature of 800°C or higher, the first raw material mixture can be calcined and vaporized in a short time, enabling efficient production of molybdenum trioxide vapor. Furthermore, a calcination temperature of 1200°C or lower is preferred as it reduces the amount of energy used in producing molybdenum trioxide powder. Moreover, a calcination temperature of 900°C or lower is preferred as it suppresses the deterioration of the sagger and calcination furnace 2 associated with calcination.

[0079] When the first raw material mixture contains not only the molybdenum oxide precursor compound and one or more of the aforementioned metal oxide-containing particles, but also metal compounds other than the molybdenum oxide precursor compound and the aforementioned one or more of the aforementioned metal oxide-containing particles, an intermediate will be generated during the roasting process of the first raw material mixture.

[0080] Specifically, for example, when the first raw material mixture contains a molybdenum oxide precursor compound and aluminum hydroxide (Al(OH)3), Al2(MoO4)3 is generated as an intermediate during the roasting process of the first raw material mixture. Therefore, it is necessary to set the roasting temperature of the first raw material mixture to a temperature above 1000°C, which is the decomposition temperature of the intermediate (Al2(MoO4)3) generated during the roasting process, so that molybdenum trioxide (MoO3) vapor is generated from the intermediate. Therefore, when the first raw material mixture contains a metal compound other than the molybdenum oxide precursor compound and one or more of the aforementioned metal oxide-containing particles, it is necessary to set the roasting temperature to a range exceeding 1000°C, for example, exceeding 1000°C but below 1100°C.

[0081] In the first roasting step S11, the sagger used for roasting the first raw material mixture can be, for example, a known sagger containing mullite-cordierite (a mixture of mullite (3Al2O3·2SiO2) and cordierite (2MgO·2Al2O3·5SiO2)), mullite, alumina, SiC, etc.

[0082] (First cooling process S12)

[0083] In the first cooling step S12, molybdenum trioxide powder is generated by cooling the molybdenum trioxide vapor generated in the first calcination step S11.

[0084] In this embodiment, such as Figure 1 As shown, by using the exhaust device 8 to discharge the gas in the cooling pipe 3 through the dust collection device 4, external gas is introduced into the cooling pipe 3 from the opening adjustment damper 6. The external gas introduced into the cooling pipe 3 cools the molybdenum trioxide vapor generated in the calcining furnace 2 and pulverizes it.

[0085] In the method for manufacturing molybdenum trioxide powder according to this embodiment, it is preferable to generate molybdenum trioxide powder with an average particle size of 1 nm or more and 100 nm or less in the first cooling step S12. Molybdenum trioxide powder with an average particle size of 100 nm or less exhibits good reactivity with sulfur, and therefore can be preferably used as a precursor for molybdenum sulfides. The average particle size of the molybdenum trioxide powder is more preferably 50 nm or less. Furthermore, molybdenum trioxide powder with an average particle size of 1 nm or more can be manufactured with good yield. The average particle size of the molybdenum trioxide powder is more preferably 1 nm or more.

[0086] In the first cooling step S12, it is preferable to generate a product with a specific surface area of ​​10 m² as measured by the BET method. 2 / g or more and 500m 2 Molybdenum trioxide powder with a specific surface area of ​​less than 10 m² / g. 2Molybdenum trioxide powder with a surface area of ​​30 m² / g or higher exhibits good reactivity with sulfur, making it a preferred precursor for molybdenum sulfides. A more preferred specific surface area for the resulting molybdenum trioxide powder is 30 m² / g. 2 / g or more. Furthermore, it is possible to manufacture products with a specific surface area of ​​500m² with good yield. 2 Molybdenum trioxide powder with a specific surface area of ​​less than 300 m² / g. 2 / g or less.

[0087] The average particle size and specific surface area of ​​the molybdenum trioxide powder generated in the first cooling step S12 can be adjusted by appropriately controlling the content of molybdenum oxide precursor compounds contained in the first raw material mixture, the cooling rate of molybdenum trioxide vapor in the cooling pipe 3, and the calcination temperature of the first raw material mixture.

[0088] Furthermore, in the first cooling step S12, it is preferable to generate molybdenum trioxide powder containing a β-crystal structure. The reason for this is that molybdenum trioxide powder containing a β-crystal structure is less stable than molybdenum trioxide powder containing an α-crystal structure and has a higher reactivity with sulfur, thus it can be preferred as a precursor for molybdenum sulfides.

[0089] (First crushing process S13)

[0090] In the first crushing step S13, the residue containing metal oxides derived from metal compound particles remaining in the sagger after the first roasting step S11 is crushed to produce the first crushed particles.

[0091] As a method for crushing the residue remaining in the crucible, known methods can be used, such as using one or more crushing devices selected from roller crushers, pin crushers, and hammer mills.

[0092] The first crushed particles (primary particles) formed in the first crushing step S13 are preferably particles with an average particle size of 2 mm or less, and more preferably particles with an average particle size of 1 μm or more and 1000 μm or less. When the first crushed particles formed in the first crushing step S13 are particles with an average particle size of 2 mm or less, using the first crushed particles as materials for the second raw material mixture in the second roasting step S21 more effectively retains the function of molten and liquefied molybdenum trioxide and reduces the contact area between the liquefied molybdenum trioxide and the crucible, thereby protecting the crucible. In addition, first crushed particles with an average particle size of 1 μm or more are preferred because they can be obtained efficiently by using a roller crusher to crush the residue containing metal oxides derived from metal compound particles. The first crushed particles are more preferably particles with an average particle size of 0.7 mm or more.

[0093] The residue remaining in the sagger after the first roasting step S11 contains metal oxides derived from the metal compound particles used in the first roasting step S11, which are formed into blocks by the first roasting step S11.

[0094] The residue remaining in the sagger after the first roasting step S11 sometimes contains molybdenum oxide precursor compounds that did not vaporize in the first roasting step S11 and remained in the sagger. Even if the residue contains molybdenum oxide precursor compounds, it can be crushed in the same way as if it did not contain molybdenum oxide precursor compounds to produce first crushed particles. In addition, even the first crushed particles containing molybdenum oxide precursor compounds can be used as materials for the second raw material mixture without hindering the second roasting step S21.

[0095] When the first raw material mixture contains only molybdenum oxide precursor compounds and one or more particles containing metal oxides selected from alumina particles, magnesium aluminate particles, titanium oxide particles, iron oxide particles, zinc oxide particles, and silica particles, the particles containing metal oxides do not vaporize in the first roasting step S11. Therefore, almost all of the particles containing metal oxides used in the first raw material mixture remain in the crucible. Therefore, when all the crushed particles produced in the first crushing step S13 are used as material for the second raw material mixture in the second roasting step S21, almost all of the particles containing metal oxides used in the first raw material mixture can be reused in the second roasting step S21.

[0096] (Second roasting step S21)

[0097] In the second roasting step S21, a second raw material mixture containing a molybdenum oxide precursor compound and the first crushed particles formed in the first crushing step S13 is loaded into a sagger. Figure 1 The molybdenum oxide precursor compound is roasted in the roasting furnace 2 shown, causing it to vaporize and form molybdenum trioxide vapor.

[0098] Regarding the second roasting step S21, except that the metal compound particles other than the molybdenum compound used as the material for the first raw material mixture in the first roasting step S11 are replaced by the first crushed particles formed in the first crushing step S13, it can be set as the same step as the first roasting step S11.

[0099] Therefore, in the second roasting step S21 and the first roasting step S11, the type and content of the molybdenum oxide precursor compound in the sagger and the second raw material mixture (the type and content of the molybdenum oxide precursor compound in the first raw material mixture), and the roasting conditions can all be set to be the same. However, as needed, some or all of the type and content of the sagger, the molybdenum oxide precursor compound, and the roasting conditions can be different. As the second raw material mixture, a raw material mixture containing the molybdenum oxide precursor compound and the first crushed particles, as well as metal compound particles other than the molybdenum compound, can be used.

[0100] The second raw material mixture preferably contains 50% to 200% by mass of the first crushed particles (or, when it contains the first crushed particles and metal compound particles other than the molybdenum compound, the total of the metal compound particles and the first crushed particles) relative to 100% by mass of the molybdenum oxide precursor compound, more preferably 100% to 200% by mass. When it contains 50% or more of the first crushed particles (or, when it contains the first crushed particles and metal compound particles other than the molybdenum compound, the total of the metal compound particles and the first crushed particles) more effectively maintains the molten and liquefied molybdenum trioxide and reduces the contact area between the liquefied molybdenum trioxide and the crucible, thereby protecting the crucible, just as when the first raw material mixture contains 50% or more of the metal compound particles. Furthermore, when the content of the first crushed particle (or, when it includes the first crushed particle and metal compound particles other than molybdenum compounds, the total of the aforementioned metal compound particles and the first crushed particle) is 200% by mass or less, similarly to when the content of metal compound particles in the first raw material mixture is 200% by mass or less, less molybdenum trioxide vapor is generated by calcination, thereby not hindering the production rate of molybdenum trioxide powder, which is preferred.

[0101] The second raw material mixture contains a molybdenum oxide precursor compound and the first crushed particles. It may contain only the molybdenum oxide precursor compound and the first crushed particles, or it may contain not only the molybdenum oxide precursor compound and the first crushed particles, but also metal compound particles other than the molybdenum oxide precursor compound and the first crushed particles.

[0102] The metal compounds that may be included in the second raw material mixture, other than the molybdenum oxide precursor compound and the first crushed particles, may be the same metal compounds listed as those that may be included in the first raw material mixture, other than the molybdenum compound particles.

[0103] The second raw material mixture preferably contains only the molybdenum oxide precursor compound and the first crushed particles. The first crushed particles do not generate intermediates during the roasting process in the second roasting step S21. Therefore, when the second raw material mixture contains only the molybdenum oxide precursor compound and the first crushed particles, it is preferable to set the roasting temperature to a low temperature below 900°C.

[0104] In the second roasting step S21, the roasting conditions such as the heating rate, roasting temperature (maximum temperature), and roasting time (holding time at the maximum temperature) during roasting of the second raw material mixture can be appropriately determined based on the molybdenum oxide precursor compound contained in the second raw material mixture, the first crushed particles, the types and contents of metal compounds other than molybdenum oxide precursor compounds and the first crushed particles that may be contained in the second raw material mixture, and the amount of the second raw material mixture.

[0105] When the second raw material mixture contains only molybdenum oxide precursor compound and the first crushed particles, similarly to the case of calcining the first raw material mixture containing only molybdenum oxide precursor compound and particles containing metal oxides selected from alumina particles, magnesium aluminate particles, titanium oxide particles, iron oxide particles, zinc oxide particles, and silica particles, the calcination temperature (maximum temperature) for calcining the second raw material mixture is preferably set to 800°C to 1200°C, more preferably to 850°C to 900°C.

[0106] (Second cooling process S22)

[0107] In the second cooling step S22, similar to the case of generating molybdenum trioxide powder in the first cooling step S12, molybdenum trioxide powder is generated by cooling the molybdenum trioxide vapor generated in the second calcination step S21.

[0108] In the second cooling step S22, for the same reasons as in the first cooling step S12, it is preferable to generate particles with an average particle size of 5 nm or more and 100 nm or less and / or a specific surface area of ​​10 m² as measured by the BET method. 2 / g or more and 500m 2 Molybdenum trioxide powder with a concentration of less than / g.

[0109] In the second cooling step S22, for the same reasons as in the first cooling step S12, it is preferable to generate molybdenum trioxide powder containing a β crystal structure.

[0110] (Second crushing process S23)

[0111] In the second crushing step S23, similar to the case in the first crushing step S13 where the residue containing metal oxides derived from metal compound particles remaining in the sagger after the first roasting step S11 is crushed, the residue containing metal oxides derived from the first crushed particles remaining in the sagger after the second roasting step S21 is crushed to produce the second crushed particles.

[0112] For the same reason as the first crushed particles formed in the first crushing step S13, the second crushed particles (primary particles) formed in the second crushing step S23 are preferably particles with an average particle size of 2 mm or less, and more preferably particles with an average particle size of 1 μm or more and 1000 μm or less.

[0113] The residue remaining in the sagger after the second roasting process S21 contains oxides of the metal from the first crushed particles used in the second roasting process S21, which are then shaped into blocks again by the second roasting process S21.

[0114] The residue remaining in the sagger after the second roasting step S21 may sometimes contain un-vaporized molybdenum oxide precursor compounds that remained in the sagger during the second roasting step S21. Even if the residue contains molybdenum oxide precursor compounds, it can be crushed to produce second crushed particles in the same way as if it did not contain molybdenum oxide precursor compounds. In addition, the second crushed particles containing molybdenum oxide precursor compounds can also be used as material for the second raw material mixture without hindering the second and subsequent second roasting steps S21.

[0115] When the second raw material mixture contains only the molybdenum oxide precursor compound and the first crushed particles, the first crushed particles do not gasify in the second roasting step S21. Therefore, almost all of the first crushed particles used as material in the second raw material mixture remain in the crucible. Therefore, if all the first crushed particles produced in the second crushing step S23 are used as material in the second raw material mixture in the second roasting step S21, all the first crushed particles used as material in the second raw material mixture in the first roasting step S21 can be reused.

[0116] In this embodiment, such as Figure 2 As shown, after the first second crushing step S23, the second roasting step S21, the second cooling step S22 and the second crushing step S23 can be performed one or more times in sequence.

[0117] like Figure 2As shown, the method for manufacturing molybdenum trioxide powder in this embodiment includes a first calcination step S11, a first cooling step S12, a first crushing step S13, a second calcination step S21, a second cooling step S22, and a second crushing step S23. Furthermore, in the method for manufacturing molybdenum trioxide powder in this embodiment, metal compound particles other than molybdenum compounds are used together with a molybdenum oxide precursor compound in the first calcination step S11; the residue containing metal oxides derived from the metal compound particles remaining in the calcined crucible is crushed to produce first crushed particles in the first crushing step S13; and the first crushed particles are used together with the molybdenum oxide precursor compound in the second calcination step S21.

[0118] Therefore, in the method for manufacturing molybdenum trioxide powder of this embodiment, the residue of metal oxides containing metal compound particles other than molybdenum compound used in the first calcination step S11 is crushed in the first crushing step S13 to produce the first crushed particles, which are then reused as materials in the second calcination step S21.

[0119] Therefore, for example, compared to not reusing the residue containing metal oxides derived from the metal compound particles other than molybdenum compounds contained in the first raw material mixture, the method for manufacturing molybdenum trioxide powder of this embodiment can reduce material costs.

[0120] Furthermore, in the method for manufacturing molybdenum trioxide powder of this embodiment, the residue remaining in the calcined sagger is crushed to form first crushed particles, which are then reused in the second calcination step S21. Therefore, it is not necessary to discard the residue remaining in the calcined sagger, and the environmental burden and disposal costs associated with such disposal are avoided.

[0121] The preferred embodiments of the present invention have been described in detail above. The present invention is not limited to specific embodiments and various modifications / changes can be made within the scope of the spirit of the present invention as set forth in the claims.

[0122] Example

[0123] Example 1

[0124] use Figure 1 The apparatus 1 shown above manufactures molybdenum trioxide powder by the method described below.

[0125] (First roasting step S11)

[0126] Prepare a first raw material mixture containing only 500g of molybdenum trioxide (MoO3) (manufactured by Nippon Inorganic Chemicals Co., Ltd., average particle size 5μm), which is a precursor compound of molybdenum oxide, and 500g of alumina (Al2O3) particles (manufactured by Sumitomo Chemical Co., Ltd., average particle size 4.8μm), which are metal compound particles other than molybdenum compounds.

[0127] The first raw material mixture was loaded into a sagger made of mullite and cordierite and roasted in a roasting furnace 2 to form molybdenum trioxide vapor. The heating rate during roasting of the first raw material mixture was set to 5℃ / min, the roasting temperature (maximum temperature) was set to 900℃, and the roasting time (holding time at the maximum temperature) was set to 10 hours.

[0128] (First cooling process S12)

[0129] use Figure 1 The exhaust system 8 shown discharges the gas from the cooling pipe 3 via the dust collection device 4, thereby adjusting the damper 6 at an opening of 4.4m. 3 External gas is introduced into the cooling pipe 3 at a flow rate of / min. This cools the molybdenum trioxide vapor generated in the calcination furnace 2 in the first calcination step S11, generating molybdenum trioxide powder.

[0130] Subsequently, the molybdenum trioxide powder captured by dust collection device 4 was recovered, and the average particle size and specific surface area of ​​the molybdenum trioxide powder were determined using the method shown below. The results are shown in Table 2.

[0131] [Method for determining average particle size]

[0132] Molybdenum trioxide powder was observed using a transmission electron microscope (TEM) at 50,000x magnification. For the smallest unit particle (i.e., the primary particle) in the obtained two-dimensional image, its major axis (the Feret diameter of the longest observed portion) and minor axis (the shorter Feret diameter perpendicular to the Feret diameter of the longest portion) were measured. The average of the major and minor axes of the primary particles was then calculated as the primary particle size. Subsequently, the primary particle sizes of 50 randomly selected molybdenum trioxide powder particles from the two-dimensional image were calculated, and their average was calculated as the average particle size of the molybdenum trioxide powder.

[0133] [Method for determining specific surface area using the BET method]

[0134] The nitrogen adsorption capacity of molybdenum trioxide powder based on the BET method was determined using a specific surface area meter (manufactured by MicrotracBEL Corp., BELSORP-mini). The surface area per 1g of molybdenum trioxide powder was calculated from the measurement results and taken as the specific surface area (m²) of the molybdenum trioxide powder. 2 / g).

[0135] (First crushing process S13)

[0136] The residue remaining in the sagger after the first roasting step S11 was crushed using a roller crusher to produce the first crushed particles (primary particles). The average particle size of the first crushed particles was determined by the method shown below. The results are shown in Table 2.

[0137] The first crushed particle was added to a 10% sodium hexametaphosphate aqueous solution and dispersed using ultrasound. The wet particle size distribution of the resulting dispersion was measured using a laser diffraction particle size distribution measuring device (device name: MASTERSIZER3000, Malvern). The average particle size of the first crushed particle was calculated using the results.

[0138] Furthermore, the composition of the first fragment was determined by elemental analysis using a fluorescence X-ray analysis device (XRF device) (trade name: Primus IV, manufactured by Rigaku Corporation). The results showed that the first fragment (residue) contained more than 90% by mass of alumina (Al₂O₃), confirming it as a blocky mass of particles bound together.

[0139] Furthermore, crystal structure analysis was performed on the first broken particles and the alumina (Al2O3) particles, which are metal compound particles other than molybdenum compounds used in the first raw material mixture, using X-ray diffraction (XRD) patterns obtained with an X-ray diffraction (XRD) apparatus (trade name: Smart Lab, manufactured by Rigaku Corporation). The results showed no significant difference between the crystal structure of the first broken particles and the crystal structure of the alumina (Al2O3) particles, which are metal compound particles other than molybdenum compounds.

[0140] (Second roasting step S21)

[0141] Except for using the first crushed particles formed in the first crushing step S13 to replace the alumina (Al2O3) particles used as the material in the first raw material mixture in the first roasting step S11, the same process as the first roasting step S11 is performed.

[0142] (Second cooling process S22)

[0143] Similar to the case where molybdenum trioxide powder is generated in the first cooling step S12, molybdenum trioxide powder is generated by cooling the molybdenum trioxide vapor generated in the second calcination step S21.

[0144] Subsequently, the molybdenum trioxide powder captured by the dust collection device 4 was recovered, and the average particle size and specific surface area of ​​the molybdenum trioxide powder were measured using the BET method, similar to the first cooling step S12. The results are shown in Table 2.

[0145] (Second crushing process S23)

[0146] Similar to the case in the first crushing step S13 where the residue remaining in the sagger after the first roasting step S11 is crushed, the residue remaining in the sagger after the second roasting step S21 is crushed to produce second crushed particles. Furthermore, the average particle size of the second crushed particles is measured in the same manner as in the first crushing step S13. The results are shown in Table 2.

[0147] Then, the second roasting process S21, the second cooling process S22, and the second crushing process S23 are repeated twice in sequence.

[0148] It should be noted that in the second roasting step S21, the second crushed particles obtained in the first crushing step S23 are used instead of the first crushed particles, and in the third roasting step S21, the second crushed particles obtained in the second crushing step S23 are used. Furthermore, in the second crushing step S23, the residue containing metal oxides from the second crushed particles obtained in the first crushing step S23 is crushed instead of the residue containing metal oxides from the first crushed particles, and in the third crushing step S23, the residue containing metal oxides from the second crushed particles obtained in the second crushing step S23 is crushed.

[0149] Furthermore, each time the second cooling step S22 is performed, the average particle size and the specific surface area measured by the BET method are determined in the same manner as in the first cooling step S12. The results are shown in Table 2.

[0150] In addition, the average particle size of the second crushed particles was measured each time the second crushing step S23 was performed, in the same manner as in the first crushing step S13. The results are shown in Table 2.

[0151] Example 2

[0152] In the first roasting step S11, 500g of magnesium aluminate (MgAl2O4) particles (manufactured by Itochu Corporation, with an average particle size of 20μm) were used instead of alumina (Al2O3) particles as metal compound particles other than molybdenum compounds. Otherwise, molybdenum trioxide powder was manufactured in the same manner as in Example 1.

[0153] In Example 2, the composition of the first crushed particles obtained in the first crushing step S13 was identified using the same method as in Example 1. The result showed that the first crushed particles (residue) contained only magnesium aluminate (MgAl2O4) and were confirmed to be lumps of particles fixed together.

[0154] Furthermore, the crystal structure analysis was performed on the first crushed particles and the magnesium aluminate (MgAl2O4) particles, which are metal compound particles other than molybdenum compounds, used in the first raw material mixture, in the same manner as in Example 1. As a result, no significant difference was observed between the crystal structure of the first crushed particles and the crystal structure of the magnesium aluminate (MgAl2O4) particles, which are metal compound particles other than molybdenum compounds.

[0155] Example 3

[0156] Except that the calcination temperature (maximum temperature) for calcining the first raw material mixture in the first calcination step S11 and the calcination temperature (maximum temperature) for calcining the second raw material mixture in the second calcination step S21 are set to 850°C, molybdenum trioxide powder is manufactured in the same manner as in Example 1.

[0157] Comparative Example 1

[0158] 750g of aluminum hydroxide (Al(OH)3) particles (manufactured by Nippon Light Metals Co., Ltd., with an average particle size of 1μm) were used instead of alumina (Al2O3) particles, which are metal compound particles other than molybdenum compounds. The calcination was carried out at a calcination temperature (maximum temperature) of 1100°C. Otherwise, as in Example 1, only the first calcination step S11 and the first cooling step S12 were performed, thereby producing molybdenum trioxide powder.

[0159] Then, the durability of the saggers used in the manufacturing methods of molybdenum trioxide powder in Examples 1 to 3 was determined by the method shown below, and evaluated by the criteria shown below.

[0160] [Method for determining the durability of saggers]

[0161] Visual inspection is used to confirm whether the saggar exhibits obvious corrosion and whether it has become unusable due to cracks. It should be noted that "obvious corrosion" refers to a condition where the erosion of the saggar wall can be visually confirmed. Furthermore, "unusable due to cracks" refers to a condition where cracks visible on the inside of the saggar are also visible on the outside.

[0162] [Criteria for evaluating the durability of saggers]

[0163] 〇: The saggar does not show obvious corrosion and has not become unusable due to cracks on the saggar.

[0164] △: The saggar shows obvious corrosion, but it is not in a state where it is unusable due to cracks.

[0165] ×: The saggar shows no obvious corrosion, but has become unusable due to cracks present on it. Or, the saggar shows obvious corrosion, but has become unusable due to cracks present on it.

[0166] Table 1 shows the materials and calcination temperatures used in the production of molybdenum trioxide powder in Examples 1 to 3 and Comparative Example 1.

[0167] [Table 1]

[0168]

[0169] In addition, Table 2 shows the average particle size and specific surface area of ​​the molybdenum trioxide powder obtained after each cooling process in Examples 1 to 3 and Comparative Example 1. Table 2 also shows the average particle size (first-stage particles after crushing) of the first crushed particles (or second crushed particles) obtained after each crushing process in Examples 1 to 3.

[0170] In addition, the molybdenum trioxide powders obtained after each cooling process in Examples 1 to 3 and Comparative Example 1 were examined using an X-ray diffraction (XRD) apparatus (trade name: Smart Lab, manufactured by Rigaku Corporation) to confirm whether they contained a β-crystal structure. The results are shown in Table 2.

[0171] [Table 2]

[0172]

[0173] In the methods for manufacturing molybdenum trioxide powder in Examples 1 to 3, after performing the first calcination step S11, the first cooling step S12, and the first crushing step S13, the second calcination step S21, the second cooling step S22, and the second crushing step S23 are repeated three times. Therefore, in the methods for manufacturing molybdenum trioxide powder in Examples 1 to 3, metal compound particles other than molybdenum compounds are used together with the molybdenum oxide precursor compound in the first calcination step S11, and the residue containing metal oxides derived from the metal compound particles remaining in the calcined crucible is crushed to produce the first crushed particles in the first crushing step S13, and the first crushed particles are used together with the molybdenum oxide precursor compound in the second calcination step S21.

[0174] Therefore, in the methods for manufacturing molybdenum trioxide powder in Examples 1 to 3, the residue containing metal oxides derived from metal compound particles other than molybdenum compounds used in the first calcination step S11 is crushed in the first crushing step S13 to produce first crushed particles, which are then reused as material in the second calcination step S21. Furthermore, the residue containing metal oxides derived from the first crushed particles used in the first (second) second calcination step S21 is crushed in the first (second) second crushing step S23 to produce second crushed particles, which are then reused as material in the second (third) second calcination step S21.

[0175] Therefore, compared with Comparative Example 1, which does not reuse the residue of metal oxides (aluminum hydroxide (Al(OH)3) particles) derived from the first raw material mixture other than molybdenum compounds, the method for manufacturing molybdenum trioxide powder in Examples 1 to 3 can reduce material costs.

[0176] Furthermore, in the methods for manufacturing molybdenum trioxide powder in Examples 1 to 3, the residue remaining in the calcined sagger is crushed to produce first crushed particles (or second crushed particles), which are then reused in the second calcination step S21. Therefore, there is no need to discard the residue remaining in the calcined sagger, and the environmental burden and disposal costs associated with discarding the residue remaining in the calcined sagger are avoided.

[0177] As shown in Table 2, no differences were observed in the average particle size and specific surface area of ​​the molybdenum trioxide powder obtained after each cooling step in the manufacturing methods of molybdenum trioxide powder in Examples 1 to 3.

[0178] Therefore, it can be confirmed that molybdenum trioxide powder of the same quality is obtained whether metal compound particles other than molybdenum compounds are used with molybdenum oxide precursor compounds or first crushed particles (or second crushed particles) are used with molybdenum oxide precursor compounds.

[0179] Furthermore, as shown in Table 2, it can be confirmed that the manufacturing methods of molybdenum trioxide powder in Examples 1 to 3 improve the durability of the crucible and suppress its deterioration compared to the manufacturing method of molybdenum trioxide powder in Comparative Example 1.

[0180] It is speculated that this is because the firing temperature was kept below 900°C in Examples 1 to 3, thereby suppressing the deterioration of the sagger that accompanied the firing.

[0181] Furthermore, in the methods for manufacturing molybdenum trioxide powder in Examples 1 to 3, the calcination temperature is below 900°C, thus reducing the amount of energy used to manufacture molybdenum trioxide powder.

[0182] Furthermore, as shown in Table 2, it can be confirmed that molybdenum trioxide powder containing a β crystal structure was generated in the first cooling step and the second cooling step of the method for manufacturing molybdenum trioxide powder in Examples 1 to 3.

Claims

1. A method for manufacturing molybdenum trioxide powder, comprising the following steps: In the first roasting process, a first raw material mixture containing a molybdenum oxide precursor compound and metal compound particles other than molybdenum compounds is loaded into a sagger for roasting, so that the molybdenum oxide precursor compound is vaporized to form molybdenum trioxide vapor. The first cooling step generates molybdenum trioxide powder by cooling the molybdenum trioxide vapor generated in the first calcination step. The first crushing process involves crushing the residue containing metal oxides derived from the metal compound particles remaining in the sagger after the first roasting process to produce the first crushed particles. In the second roasting process, the second raw material mixture containing the molybdenum oxide precursor compound and the first crushed particles is loaded into a sagger for roasting, so that the molybdenum oxide precursor compound is vaporized to form molybdenum trioxide vapor. The second cooling step generates molybdenum trioxide powder by cooling the molybdenum trioxide vapor generated in the second calcination step; and, The second crushing process involves crushing the residue containing metal oxides originating from the first crushed particles remaining in the sagger after the second roasting process to produce the second crushed particles.

2. The method of producing molybdenum trioxide powder according to claim 1, wherein The average particle size of the first and second crushed particles is less than 1 mm.

3. The method of producing molybdenum trioxide powder according to claim 1, wherein The metal compound particles are selected from one or more of the following: alumina particles, magnesium aluminate particles, titanium oxide particles, iron oxide particles, zinc oxide particles, and silicon dioxide particles.

4. The method of producing molybdenum trioxide powder according to claim 3, wherein The first raw material mixture contains only the molybdenum oxide precursor compound and the metal compound particles, and in the first roasting step, roasting is carried out at a temperature above 800°C and below 1200°C. The second raw material mixture contains only the molybdenum oxide precursor compound and the first crushed particles, and in the second roasting process, roasting is carried out at a temperature above 800°C and below 1200°C.

5. The method of producing molybdenum trioxide powder according to claim 3, wherein The first raw material mixture contains more than 50% by mass and less than 200% by mass of the metal compound particles relative to 100% by mass of the molybdenum oxide precursor compound. The second raw material mixture contains more than 50% by mass and less than 200% by mass of the first crushed particles relative to 100% by mass of the molybdenum oxide precursor compound.

6. The method for manufacturing molybdenum trioxide powder according to claim 1, wherein, In the first and second cooling processes, molybdenum trioxide powder with an average particle size of 5 nm or more and 100 nm or less is generated.

7. The method for manufacturing molybdenum trioxide powder according to claim 1, wherein, In the first cooling step and the second cooling step, molybdenum trioxide powder having a specific surface area of 10 m 2 / g or more and 500 m 2 / g or less, measured by the BET method, is produced.

8. The method for manufacturing molybdenum trioxide powder according to claim 1, wherein, In the first and second cooling processes, molybdenum trioxide powder containing a β crystal structure is generated.

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