Molybdenum trioxide powder, apparatus for producing molybdenum trioxide powder, and method for producing molybdenum trioxide powder

Abstract

This molybdenum trioxide powder has a specific surface area, as measured using the BET method, of 100 mｍ2 / g-500 m2 / g. The molybdenum trioxide powder may have a median diameter D50 of 5-1000 nm, as determined using a dynamic light scattering method. The molybdenum trioxide powder may have a purity of 99 mass% or more. The molybdenum trioxide powder may include molybdenum trioxide having a β crystal structure.

Description

Molybdenum Trioxide Powder, Manufacturing Apparatus for Molybdenum Trioxide Powder, and Manufacturing Method for Molybdenum Trioxide Powder

[0001] The present invention relates to molybdenum trioxide powder, a manufacturing apparatus for molybdenum trioxide powder, and a manufacturing method for molybdenum trioxide powder. This application claims priority based on Japanese Patent Application No. 2024-215395, filed in Japan on December 10, 2024, and incorporates its content herein by reference.

[0002] Conventionally, molybdenum sulfides such as molybdenum disulfide (MoS ２ 2) are widely used, for example, as lubricants, steel additives, and raw materials for molybdates. As a method for producing molybdenum sulfide, there is a method using molybdenum trioxide powder as a precursor.

[0003] Conventionally, as a method for producing molybdenum trioxide powder, there is a method including vaporizing a molybdenum oxide precursor compound to form molybdenum trioxide vapor and cooling the molybdenum trioxide vapor (see, for example, Patent Document 1). Patent Document 1 describes a molybdenum trioxide powder containing an aggregate of primary particles including the crystal structure of molybdenum trioxide, the crystal structure including an α-crystal having an average crystallite size of 50 nm or less, and the median diameter D ５０ of the primary particles determined by the dynamic light scattering method is 2000 nm or less. Further, Patent Document 1 describes a molybdenum trioxide powder having a specific surface area measured by the BET method of 10 m ２ 2 / g or more.

[0004] International Publication No. 2022 / 202757 (A)

[0005] However, in conventional molybdenum trioxide powder used as a precursor for molybdenum sulfide, in order to further improve the reactivity with sulfur, a larger specific surface area measured by the BET method is required.

[0006] The present invention has been made in view of the above circumstances, and aims to provide molybdenum trioxide powder that has a larger specific surface area as measured by the BET method and can be suitably used as a precursor of molybdenum sulfide. Furthermore, the present invention aims to provide a production apparatus and method for molybdenum trioxide powder that can be suitably used when producing the molybdenum trioxide powder of the present invention, which has a large specific surface area as measured by the BET method.

[0007] [1] The specific surface area measured by the BET method is 100 m² ２ / g or more 500m ２ Molybdenum trioxide powder with a concentration of less than or equal to / g. [2] Median diameter D determined by dynamic light scattering. ５０ [1] Molybdenum trioxide powder, wherein the wavelength is 5 nm or more and 1000 nm or less. [3] Molybdenum trioxide powder, wherein the purity is 99% by mass or more, as described in [1] or [2]. [4] Molybdenum trioxide powder, wherein the wavelength is β-crystalline molybdenum, as described in any of [1] to [3].

[0008] [5] A molybdenum trioxide powder manufacturing apparatus used for manufacturing the molybdenum trioxide powder described in any of [1] to [4], comprising: a calcination furnace for calcining and vaporizing a raw material containing a molybdenum oxide precursor compound; a cooling pipe connected to the calcination furnace for cooling and pulverizing the molybdenum trioxide vapor vaporized in the calcination furnace; a plurality of dust collectors for recovering the pulverized molybdenum trioxide powder, which are interchangeably connected to the cooling pipe; and an exhaust device connected to the plurality of dust collectors, wherein the exhaust device discharges the gas in the cooling pipe through one of the plurality of dust collectors, thereby blowing outside air into the cooling pipe.

[0009] [6] The molybdenum trioxide powder production apparatus according to [5], wherein the plurality of dust collectors consist of a first dust collector and a second dust collector, and the first dust collector and the second dust collector are alternately connected to the cooling pipe.

[0010] [7] A method for producing molybdenum trioxide powder using the molybdenum trioxide powder production apparatus described in [5], comprising: a vaporization step of firing a raw material containing a molybdenum oxide precursor compound in the firing furnace to vaporize it and form molybdenum trioxide vapor; a powdering step of cooling the molybdenum trioxide vapor with outside air blown into the cooling pipe to powderize it, wherein the powdering step comprises: a first powdering step of connecting a first dust collector selected from the plurality of dust collectors to the cooling pipe and blowing outside air into the cooling pipe by exhausting the gas in the cooling pipe via the first dust collector with the exhaust device; and a second powdering step of connecting a second dust collector other than the first dust collector selected from the plurality of dust collectors to the cooling pipe and blowing outside air into the cooling pipe by exhausting the gas in the cooling pipe via the second dust collector with the exhaust device.

[0011] [8] The method for producing molybdenum trioxide powder according to [7], wherein the first dust collector and the second dust collector are alternately connected to the cooling pipe, and in the powdering step, the first powdering step and the second powdering step are performed alternately at predetermined intervals.

[0012] [9] The method for producing molybdenum trioxide powder according to [8], wherein the powdering step is a step of performing the first powdering step and the second powdering step alternately multiple times in this order, and includes a first discharge step of discharging the molybdenum trioxide powder recovered by the first dust collector from the first dust collector while the second powdering step is being performed, and a second discharge step of discharging the molybdenum trioxide powder recovered by the second dust collector from the second dust collector while the second and subsequent first powdering steps are being performed.

[0013]

[10] A method for producing molybdenum trioxide powder according to any one of [7] to [9], wherein in the vaporization step, the raw material is calcined at a calcination temperature of 800°C or more and 1100°C or less.

[0014]

[11] The production method of molybdenum trioxide powder according to any one of [7] to

[10] , wherein the raw material contains a metal oxide other than the molybdenum oxide precursor compound in an amount of 50% by mass or more and 400% by mass or less based on 100% by mass of the molybdenum oxide precursor compound.

[12] The production method of molybdenum trioxide powder according to

[11] , wherein the metal oxide is any one or two or more selected from aluminum hydroxide, boehmite, and alumina.

[0015]

[13] In the first powdering step and the second powdering step, the introduction amount of outside air blown into the cooling pipe per unit time is 4.0 m ３ / min to 20 m ３ / min. The production method of molybdenum trioxide powder according to any one of [7] to

[12] .

[14] The production method of molybdenum trioxide powder according to any one of [7] to

[13] , wherein the raw material is fired in the firing furnace under a pressure of -5000 Pa to -800 Pa.

[0016] The molybdenum trioxide powder of the present invention has a specific surface area measured by the BET method of 100 m ２ / g or more and 500 m ２ / g or less. Therefore, the molybdenum trioxide powder of the present invention has good reactivity with sulfur and is suitable as a precursor of molybdenum sulfide. In addition, since the molybdenum trioxide powder of the present invention has a large specific surface area measured by the BET method, it can be used as a catalyst having excellent performance. Further, since the molybdenum trioxide powder of the present invention has a large specific surface area measured by the BET method, a molybdenum trioxide dispersion liquid having good transparency can be formed by dispersing it in a dispersion medium.

[0017] The present invention provides a molybdenum trioxide powder manufacturing apparatus comprising: a calcination furnace for calcining and vaporizing a raw material containing a molybdenum oxide precursor compound; a cooling pipe connected to the calcination furnace for cooling and pulverizing the molybdenum trioxide vapor vaporized in the calcination furnace; a plurality of dust collectors for recovering the pulverized molybdenum trioxide powder, which are interchangeably connected to the cooling pipe; and an exhaust device connected to the plurality of dust collectors. The exhaust device discharges the gas in the cooling pipe through one of the plurality of dust collectors, thereby blowing outside air into the cooling pipe.

[0018] Therefore, in the molybdenum trioxide powder manufacturing apparatus of the present invention, for example, a first dust collector selected from a plurality of dust collectors is connected to a cooling pipe to manufacture molybdenum trioxide powder, and before the filter installed in the first dust collector becomes clogged, a second dust collector other than the first dust collector, selected from the plurality of dust collectors, is connected to the cooling pipe to manufacture molybdenum trioxide powder. This eliminates the reduction in the amount of outside air introduced per unit time into the cooling pipe caused by the clogging of the filter installed in the first dust collector.

[0019] Therefore, the molybdenum trioxide powder manufacturing apparatus of the present invention can stably supply a sufficiently large amount of outside air into the cooling piping, compared to, for example, a manufacturing apparatus with only one dust collector. Thus, the molybdenum trioxide powder manufacturing apparatus of the present invention can be suitably used when manufacturing the molybdenum trioxide powder of the present invention, which has a small particle size and a large specific surface area as measured by the BET method.

[0020] Furthermore, when using the molybdenum trioxide powder manufacturing apparatus of the present invention, for example, if a first dust collector selected from a plurality of dust collectors is connected to a cooling pipe to manufacture molybdenum trioxide powder, and then a second dust collector other than the first dust collector selected from the plurality of dust collectors is connected to the cooling pipe to manufacture molybdenum trioxide powder, the pulverized molybdenum trioxide powder recovered by the first dust collector can be removed from the filter installed in the first dust collector while the molybdenum trioxide powder is being manufactured with the second dust collector connected to the cooling pipe. In other words, clogging of the filter installed in the first dust collector can be resolved while manufacturing molybdenum trioxide powder using the second dust collector.

[0021] The present invention provides a method for producing molybdenum trioxide powder, comprising a vaporization step of forming molybdenum trioxide vapor by calcining and vaporizing a raw material containing a molybdenum oxide precursor compound in a calcination furnace, and a powdering step of cooling the molybdenum trioxide vapor with outside air blown into a cooling pipe to pulverize it. Furthermore, in the method for producing molybdenum trioxide powder of the present invention, the powdering step includes a first powdering step in which a first dust collector selected from a plurality of dust collectors is connected to the cooling pipe, and outside air is blown into the cooling pipe by exhausting the gas in the cooling pipe via the first dust collector using an exhaust device, and a second powdering step in which any second dust collector other than the first dust collector selected from a plurality of dust collectors is connected to the cooling pipe, and outside air is blown into the cooling pipe by exhausting the gas in the cooling pipe via the second dust collector using an exhaust device.

[0022] Therefore, in the method for producing molybdenum trioxide powder of the present invention, for example, even if the filter installed in the first dust collector becomes clogged in the first powdering step, the reduction in the amount of outside air introduced per unit time into the cooling pipe, which is caused by the clogging of the filter installed in the first dust collector, can be eliminated by starting the second powdering step. Accordingly, the method for producing molybdenum trioxide powder of the present invention allows for a stable supply of a sufficiently large amount of outside air into the cooling pipe. Thus, by using the method for producing molybdenum trioxide powder of the present invention, it is possible to produce molybdenum trioxide powder of the present invention, which has a small particle size and a large specific surface area as measured by the BET method.

[0023] Figure 1 is a schematic diagram illustrating an example of a molybdenum trioxide powder manufacturing apparatus according to this embodiment. Figure 2 is a graph showing the relationship between the concentration of pulverized molybdenum trioxide in the cooling pipe 3 and the specific surface area of ​​the recovered molybdenum trioxide powder measured by the BET method in the process of manufacturing molybdenum trioxide powder according to Example 4.

[0024] To solve the above problems and produce molybdenum trioxide powder with a larger specific surface area as measured by the BET method, the inventors focused on the relationship between the specific surface area of ​​molybdenum trioxide powder produced using the production apparatus shown below and the production conditions, and conducted diligent studies as shown below.

[0025] Specifically, we investigated a case where a molybdenum trioxide powder manufacturing apparatus was used, comprising a calcination furnace for calcining and vaporizing raw materials containing a molybdenum oxide precursor compound, a cooling pipe connected to the calcination furnace for cooling and pulverizing the molybdenum trioxide vapor vaporized in the calcination furnace, a dust collector connected to the cooling pipe for recovering the pulverized molybdenum trioxide powder, and an exhaust device connected to the dust collector, wherein the exhaust device discharges the gas in the cooling pipe via the dust collector, thereby blowing outside air into the cooling pipe.

[0026] As a result, it was found that increasing the amount of outside air introduced per unit time into the cooling pipe lowers the density of molybdenum trioxide molecules in the cooling pipe, increases the cooling rate of molybdenum trioxide vapor, and makes it easier to generate molybdenum trioxide powder with a large specific surface area. However, when producing molybdenum trioxide powder using the above manufacturing apparatus, it was difficult to increase the amount of outside air introduced per unit time into the cooling pipe for the following reasons.

[0027] In other words, the amount of outside air introduced into the cooling pipe per unit time is determined by the amount of gas in the cooling pipe discharged through the dust collector by the exhaust device. When the production of molybdenum trioxide powder is started using the above-described manufacturing apparatus, the generated molybdenum trioxide powder is collected in the dust collector. As a result, the filter in the dust collector gradually becomes clogged, and the amount of gas in the cooling pipe discharged through the dust collector gradually decreases. Consequently, the amount of outside air introduced into the cooling pipe per unit time is reduced.

[0028] Therefore, the inventors diligently studied how to eliminate the clogging of the filter in the dust collector caused by the generated molybdenum trioxide powder. As a result, they found that a manufacturing apparatus should be configured in which multiple dust collectors are interchangeably connected to the cooling pipe, and the gas in the cooling pipe is discharged through one of the multiple dust collectors by an exhaust device, thereby blowing outside air into the cooling pipe.

[0029] In such a molybdenum trioxide powder manufacturing apparatus, for example, even if the filter installed in the first dust collector, which is selected from among multiple dust collectors, becomes clogged with molybdenum trioxide powder recovered by the first dust collector, the reduction in the amount of outside air introduced per unit time into the cooling pipe, which is caused by the clogging of the filter installed in the first dust collector, can be eliminated by connecting the cooling pipe to a second dust collector, which is not the first dust collector, which is also selected from among multiple dust collectors. Therefore, by manufacturing molybdenum trioxide powder using this manufacturing apparatus, a sufficiently large amount of outside air can be stably supplied into the cooling pipe compared to, for example, a manufacturing apparatus with only one dust collector.

[0030] Furthermore, the inventors of the present invention have come up with the present invention after confirming that by adjusting the suction capacity of the exhaust device using the above-described molybdenum trioxide powder manufacturing apparatus, the amount of outside air introduced per unit time into the cooling pipe can be controlled, and molybdenum trioxide powder with a sufficiently small particle size and a sufficiently large specific surface area as measured by the BET method can be manufactured.

[0031] The molybdenum trioxide powder, the apparatus for producing molybdenum trioxide powder, and the method for producing molybdenum trioxide powder of the present invention will be described in detail below with reference to the drawings. Note that, for convenience, the drawings used in the following description may show enlarged versions of characteristic parts to make the features of the present invention easier to understand. Therefore, the dimensional ratios of each component may differ from those of the actual product. 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, if multiple upper and lower limits are specified for a particular parameter, any combination of these upper and lower limits can be used to create a suitable numerical range.

[0032] [Molybdenum trioxide powder] The molybdenum trioxide powder of this embodiment has a specific surface area of ​​100 m² as measured by the BET method. ２ / g or more 500m ２ It is less than / g. The molybdenum trioxide powder of this embodiment has a specific surface area of ​​100 m² as measured by the BET method. ２ Because it is 1 / g or more, it has good reactivity with sulfur and can be suitably used as a precursor for molybdenum sulfide. Furthermore, the molybdenum trioxide powder of this embodiment has a specific surface area of ​​100 m² as measured by the BET method. ２ Because it is 1 / g or more, it can be used as a catalyst with excellent performance. Furthermore, the molybdenum trioxide powder of this embodiment has a specific surface area of ​​100 m² as measured by the BET method. ２ Because the concentration is greater than or equal to 1g, dispersing it in a dispersion medium can form a highly transparent molybdenum trioxide dispersion.

[0033] In this embodiment, the molybdenum trioxide powder exhibits an even more pronounced effect due to its large specific surface area as measured by the BET method, therefore, 110 m ２ It is preferable that the amount be 120 m or more. ２ It is more preferable that it be 130m or more per gram. ２ It is even more preferable that the amount is greater than or equal to / g.

[0034] The molybdenum trioxide powder of this embodiment has a specific surface area of ​​500 m² as measured by the BET method. ２Since it is less than / g, it can be manufactured by the manufacturing method described later. The molybdenum trioxide powder of this embodiment is easy to manufacture, so 400m ２ It is preferable that the amount is less than or equal to 300m ２ It is more preferable that it be less than or equal to 200m ２ It is even more preferable that the amount is less than or equal to / g.

[0035] The molybdenum trioxide powder of this embodiment has a median diameter D determined by dynamic light scattering. ５０ It is preferable that the median diameter D is between 5 nm and 1000 nm. ５０ Molybdenum trioxide powder having a median diameter of 5 nm or more can be produced by the manufacturing method described later. The molybdenum trioxide powder of this embodiment is easy to manufacture, and therefore has a median diameter of D ５０ It is preferable that the wavelength is 8 nm or more, more preferably 10 nm or more, and even more preferably 15 nm or more.

[0036] Median diameter D of molybdenum trioxide powder in this embodiment ５０ If the median diameter D is 1000 nm or less, the reactivity with sulfur is better, allowing it to be used as a catalyst with superior performance, and moreover, dispersing it in a dispersion medium will form a molybdenum trioxide dispersion with better transparency. The molybdenum trioxide powder of this embodiment has a median diameter D ５０ Preferably, the wavelength is 100 nm or less, more preferably 50 nm or less, and even more preferably 30 nm or less.

[0037] The molybdenum trioxide powder of this embodiment preferably has a purity of 99% by mass or higher, and more preferably 99.90% by mass or higher. When the purity of the molybdenum trioxide powder is 99% by mass or higher, it can be more preferably used as a precursor for molybdenum sulfide, which can produce high-purity molybdenum sulfide. When the purity of the molybdenum trioxide powder is 99.99% by mass or lower, it is preferable because it can be easily produced by the manufacturing method described later.

[0038] The molybdenum trioxide powder of this embodiment preferably contains molybdenum trioxide with a β-crystalline structure. The reason for this is as follows: Molybdenum trioxide powder containing a β-crystalline structure is less stable than molybdenum trioxide powder with an α-crystalline structure. Therefore, molybdenum trioxide powder containing a β-crystalline structure has higher catalytic activity and reactivity compared to molybdenum trioxide powder with an α-crystalline structure, and when used as a precursor for molybdenum sulfide, it has good reactivity with sulfur and can therefore be preferably used.

[0039] [Molybdenum Trioxide Powder Manufacturing Apparatus] Next, the molybdenum trioxide powder manufacturing apparatus of this embodiment will be described in detail. Figure 1 is a schematic diagram illustrating an example of the molybdenum trioxide powder manufacturing apparatus of this embodiment. The molybdenum trioxide powder manufacturing apparatus 1 shown in Figure 1 includes a calcination furnace 2, cooling pipes 3, a first dust collector 4a and a second dust collector 4b, and an exhaust air device 8.

[0040] The firing furnace 2 fires and vaporizes the raw material containing the molybdenum oxide precursor compound at a predetermined temperature. A known type of firing furnace 2 can be used. As shown in Figure 1, an exhaust port 5 is provided on the ceiling surface of the firing furnace 2.

[0041] The cooling pipe 3 cools and pulverizes molybdenum trioxide vapor, which is vaporized by firing the raw material containing the molybdenum oxide precursor compound in the firing furnace 2. The cooling pipe 3 is made of stainless steel such as SUS304 and has a cross shape when viewed from the side, as shown in Figure 1. The lower end of the cooling pipe 3 is connected to the exhaust port 5 of the firing furnace 2. An observation window 7 for observing the inside of the cooling pipe 3 is located at the upper end of the cooling pipe 3.

[0042] Furthermore, an outside air intake (not shown) is provided at the first horizontal end of the cooling pipe 3. As shown in Figure 1, an opening adjustment damper 6 is positioned at the outside air intake to adjust the opening degree of the outside air intake.

[0043] A dust collection pipe 40 is connected to the second horizontal end of the cooling pipe 3. As shown in Figure 1, the dust collection pipe 40 connects the cooling pipe 3 to a three-way valve 43. The dust collection pipe 40 communicates with either the first dust collection pipe 41 or the second dust collection pipe 42 by switching the three-way valve 43. Any known three-way valve 43 can be used. Specifically, a commercially available air-driven bag filter switching valve can be used as the three-way valve 43.

[0044] The first dust collection pipe 41 connects the dust collection pipe 40 to the first dust collector 4a. The second dust collection pipe 42 connects the dust collection pipe 40 to the second dust collector 4b. Therefore, in the molybdenum trioxide powder manufacturing apparatus 1 shown in Figure 1, the first dust collector 4a and the second dust collector 4b are alternately connected to the cooling pipe 3 by switching the three-way valve 43.

[0045] In the molybdenum trioxide powder manufacturing apparatus 1 shown in Figure 1, two dust collectors, a first dust collector 4a and a second dust collector 4b, recover the molybdenum trioxide powder that has been pulverized in the cooling pipe 3. Known dust collectors can be used as the first dust collector 4a and the second dust collector 4b. The first dust collector 4a and the second dust collector 4b shown in Figure 1 consist, for example, of a dry cyclone (not shown) and a dust collector. The dry cyclone swirls the gas containing molybdenum trioxide powder supplied from the cooling pipe 3 through piping inside a cylindrical container, using centrifugal force to remove coarse particles and foreign matter. The dust collector receives the gas from which coarse particles and foreign matter have been removed by the dry cyclone and passes it through a filter to recover the molybdenum trioxide powder contained in the gas. As the filter provided in the dust collector, for example, a known filter made of a material with excellent heat insulation properties and a mesh size of about 10 μm can be used.

[0046] The first dust collector 4a and the second dust collector 4b may be the same or different. It is preferable that the first dust collector 4a and the second dust collector 4b are the same, as this allows for easy adjustment of manufacturing conditions such as the pressure inside the firing furnace 2 when firing the raw materials and the amount of outside air introduced per unit time into the cooling pipe 3.

[0047] The exhaust device 8 draws gas from the first dust collector 4a or the second dust collector 4b via the suction pipe 50 and the first suction pipe 51 or the second suction pipe 52. A known device such as a blower can be used as the exhaust device 8.

[0048] A suction pipe 50 is connected to the exhaust device 8. As shown in Figure 1, the suction pipe 50 connects the exhaust device 8 to a three-way valve 53. The suction pipe 50 communicates with either the first suction pipe 51 or the second suction pipe 52 by switching the three-way valve 53. A known type of three-way valve 53 can be used. Specifically, a commercially available air-driven bag filter switching valve can be used as the three-way valve 53.

[0049] The first suction pipe 51 connects the suction pipe 50 to the first dust collector 4a. The second suction pipe 52 connects the suction pipe 50 to the second dust collector 4b. Therefore, in the molybdenum trioxide powder manufacturing apparatus 1 shown in Figure 1, the first dust collector 4a and the second dust collector 4b are alternately connected to the exhaust device 8 by switching the three-way valve 53.

[0050] In the molybdenum trioxide powder manufacturing apparatus 1 shown in Figure 1, the three-way valve 53 is switched to connect the suction pipe 50 to the first suction pipe 51 when the dust collection pipe 40 and the first dust collection pipe 41 are connected by the three-way valve 43. Also, when the dust collection pipe 40 and the second dust collection pipe 42 are connected by the three-way valve 43, the three-way valve 53 is switched to connect the suction pipe 50 to the second suction pipe 52.

[0051] As a result, in the molybdenum trioxide powder manufacturing apparatus 1 shown in Figure 1, when the cooling pipe 3 is connected to the first dust collector 4a, the exhaust air device 8 is also connected to the first dust collector 4a, and when the cooling pipe 3 is connected to the second dust collector 4b, the exhaust air device 8 is also connected to the second dust collector 4b.

[0052] In the molybdenum trioxide powder manufacturing apparatus 1 shown in Figure 1, for example, when the dust collection pipe 40 and the first dust collection pipe 41 are connected by a three-way valve 43, outside air is blown into the cooling pipe 3 as shown below. That is, when the dust collection pipe 40 and the first dust collection pipe 41 are connected by a three-way valve 43, the suction pipe 50 and the first suction pipe 51 are connected by a three-way valve 53. Then, as shown in Figure 1, the exhaust device 8 draws in the first dust collector 4a via the suction pipe 50 and the first suction pipe 51. Furthermore, the cooling pipe 3 connected to the first dust collector 4a is drawn in via the dust collection pipe 40 and the first dust collection pipe 41. As a result, the gas in the cooling pipe 3 is discharged, and outside air is blown into the cooling pipe 3 from the opening adjustment damper 6.

[0053] Furthermore, for example, when the dust collection pipe 40 and the second dust collection pipe 42 are connected by a three-way valve 43, outside air is blown into the cooling pipe 3 as shown below. That is, when the dust collection pipe 40 and the second dust collection pipe 42 are connected by a three-way valve 43, the suction pipe 50 and the second suction pipe 52 are connected by a three-way valve 53. Then, as shown in Figure 1, the exhaust device 8 sucks the second dust collector 4b through the suction pipe 50 and the second suction pipe 52. Furthermore, the cooling pipe 3 connected to the second dust collector 4b is sucked through the dust collection pipe 40 and the second dust collection pipe 42. As a result, the gas in the cooling pipe 3 is discharged, and outside air is blown into the cooling pipe 3 from the opening adjustment damper 6.

[0054] Therefore, when producing molybdenum trioxide powder using the molybdenum trioxide powder production apparatus 1 shown in Figure 1, the amount of outside air introduced per unit time into the cooling pipe 3 and the pressure inside the firing furnace 2 when firing the raw material can be adjusted by the suction capacity of the exhaust device 8. The more the amount of outside air introduced per unit time into the cooling pipe 3 is increased and the lower the pressure inside the firing furnace 2 when firing the raw material, the larger the specific surface area of ​​the produced molybdenum trioxide powder, as measured by the BET method, tends to be.

[0055] Therefore, when manufacturing molybdenum trioxide powder using the manufacturing apparatus 1 shown in Figure 1, the specific surface area of ​​the manufactured molybdenum trioxide powder, as measured by the BET method, can be controlled by adjusting the suction capacity of the exhaust fan 8 to control the amount of outside air introduced per unit time into the cooling pipe 3 and the pressure inside the firing furnace 2 when firing the raw material.

[0056] [Method for producing molybdenum trioxide powder] Next, the method for producing molybdenum trioxide powder according to this embodiment will be explained in detail, using the example of producing molybdenum trioxide powder using the molybdenum trioxide powder production apparatus 1 shown in Figure 1.

[0057] (Vaporization process) In the method for producing molybdenum trioxide powder of this embodiment, first, a vaporization process is performed in which a raw material containing a molybdenum oxide precursor compound is calcined and vaporized in the calcination furnace 2 shown in Figure 1 to form molybdenum trioxide vapor.

[0058] The molybdenum oxide precursor compound included in the raw materials used in the vaporization process is not particularly limited, as long as it can form molybdenum trioxide vapor when calcined. The form of the molybdenum oxide precursor compound included in the raw materials used in the vaporization process is not particularly limited. For example, it may be in powder form, such as molybdenum trioxide powder, or in liquid form, such as an aqueous solution of ammonium molybdate. The form of the molybdenum oxide precursor compound is preferably in powder form because it is easy to handle and energy efficient.

[0059] Examples of molybdenum oxide precursor compounds included in the raw materials used in the vaporization process include metallic molybdenum, molybdenum trioxide, molybdenum dioxide, molybdenum sulfide, ammonium molybdate, and phosphomolybdic acid (H ３ PMo １２ O ４０ ), silicic acid (H ４ SiMo １２ O ４０ ), aluminum molybdate, silicon molybdate, magnesium molybdate (MgMo ｎ O ３ｎ＋１ (n=1-3), sodium molybdate (Na２ Mo ｎ O ３ｎ＋１ (n=1-3), titanium molybdate, iron molybdate, potassium molybdate (K ２ Mo ｎ O ３ｎ＋１ (n=1-3), zinc molybdate, boron molybdate, lithium molybdate (Li ２ Mo ｎ O ３ｎ＋１ Examples include (n=1-3), cobalt molybdate, nickel molybdate, manganese molybdate, chromium molybdate, cesium molybdate, barium molybdate, strontium molybdate, yttrium molybdate, zirconium molybdate, and copper molybdate. These molybdenum oxide precursor compounds may be used individually or in combination of two or more.

[0060] Of the above molybdenum oxide precursor compounds, it is preferable to include molybdenum trioxide from the viewpoint of easily controlling the purity, average particle size, and crystal structure of the molybdenum trioxide powder produced. In particular, it is preferable to use commercially available α-crystalline molybdenum trioxide as the molybdenum oxide precursor compound. Furthermore, when ammonium molybdate is used as the molybdenum oxide precursor compound, it is converted to thermodynamically stable molybdenum trioxide by calcination, so the vaporized molybdenum oxide precursor compound becomes molybdenum trioxide.

[0061] The raw materials used in the vaporization process may contain metal oxides other than the molybdenum oxide precursor compound, or they may not contain metal oxides other than the molybdenum oxide precursor compound. When the raw materials contain metal oxides other than the molybdenum oxide precursor compound, the proportion of molybdenum trioxide vapor generated from the raw materials during the calcination process decreases. This makes it easier for the density of molybdenum trioxide molecules in the cooling pipe 3 to decrease, the cooling rate of the molybdenum trioxide vapor to increase, and the generation of molybdenum trioxide powder with a large specific surface area to be facilitated, which is preferable. Furthermore, when metal oxides other than the molybdenum trioxide precursor compound are included, the contact area between the liquefied molybdenum trioxide and the sheath is reduced by the metal oxides, thus protecting the sheath. On the other hand, when the raw materials do not contain metal oxides other than the molybdenum oxide precursor compound, the purity of the generated molybdenum trioxide powder tends to be higher compared to when metal oxides other than the molybdenum oxide precursor compound is included, which is preferable.

[0062] Examples of metal oxides other than molybdenum oxide precursor compounds that may be included in the raw materials include aluminum compounds, silicon compounds, titanium compounds, magnesium compounds, sodium compounds, potassium compounds, zirconium compounds, yttrium compounds, zinc compounds, copper compounds, and iron compounds. Of these, it is preferable to use one or more selected from aluminum compounds, silicon compounds, titanium compounds, and magnesium compounds as the metal oxide other than the molybdenum oxide precursor compound.

[0063] In particular, as a metal oxide other than molybdenum oxide precursor compounds that may be included in the raw materials, it is preferable to use aluminum compounds because they are inexpensive and readily available. Examples of aluminum compounds include magnesium aluminate, aluminum chloride, aluminum sulfate, basic aluminum acetate, aluminum hydroxide, boehmite, pseudoboehmite, transition aluminum oxides (such as γ-aluminum oxide, δ-aluminum oxide, and θ-aluminum oxide), α-aluminum oxide, and mixed aluminum oxides having two or more crystalline phases, and it is preferable that one or more are selected from aluminum hydroxide, boehmite, and alumina.

[0064] When the raw materials used in the vaporization process contain metal oxides other than the molybdenum oxide precursor compound, it is preferable that the metal oxides other than the molybdenum oxide precursor compound be present in an amount of 50% to 400% by mass, and more preferably 100% to 200% by mass, relative to 100% by mass of the molybdenum oxide precursor compound.

[0065] It is preferable that the content of metal oxides other than the molybdenum oxide precursor compound is 50% by mass or more relative to 100% by mass of the molybdenum oxide precursor compound, as this tends to lower the density of molybdenum trioxide molecules in the cooling pipe 3, increasing the cooling rate of molybdenum trioxide vapor and significantly promoting the formation of molybdenum trioxide powder with a large specific surface area. Furthermore, when metal oxides are included at a concentration of 50% by mass or more, the function of the metal oxides in protecting the sheath by reducing the contact area between the liquefied molybdenum trioxide and the sheath is more effectively exhibited.

[0066] Furthermore, it is preferable that the content of metal oxides other than the molybdenum oxide precursor compound is 400% by mass or less relative to 100% by mass of the molybdenum oxide precursor compound, as this prevents the purity of the resulting molybdenum trioxide powder from becoming insufficient due to the presence of metal oxides other than the molybdenum oxide precursor compound in the raw material.

[0067] In the vaporization process, the calcination temperature for burning the raw materials is preferably 800°C to 1100°C, and more preferably 900°C to 1100°C. The calcination temperature can be appropriately determined depending on the type of molybdenum oxide precursor compound used, and, if other metal oxides are included, the type of metal oxide other than the molybdenum oxide precursor compound. If the raw materials contain metal oxides other than the molybdenum oxide precursor compound, it is preferable to set the calcination temperature above the temperature at which the intermediates generated during the calcination process decompose. This is because the resulting molybdenum trioxide powder will have a high purity.

[0068] For example, when a molybdenum compound is used as the molybdenum oxide precursor compound, and an aluminum compound such as aluminum hydroxide is used as the metal oxide other than the molybdenum oxide precursor compound, aluminum molybdate may be formed as an intermediate. Therefore, it is preferable to set the firing temperature to be above the temperature at which aluminum molybdate decomposes. Specifically, when an aluminum compound is used as the metal oxide other than the molybdenum oxide precursor compound, it is preferable to set the firing temperature to 900°C or higher.

[0069] If the calcination temperature for burning the raw materials in the vaporization process is 900°C or higher, the raw materials can be calcined and vaporized in a short time, and molybdenum trioxide vapor can be efficiently generated. Furthermore, if the calcination temperature is 1100°C or lower, the amount of energy used in the production of molybdenum trioxide powder can be reduced, which is preferable.

[0070] In the vaporization process, the heating rate in the firing furnace 2 when firing the raw materials can be appropriately determined according to the type of molybdenum oxide precursor compound used, and, if other metal oxides are included, the type of metal oxides other than the molybdenum oxide precursor compound. The heating rate is preferably 0.1°C / min or more, more preferably 1°C / min or more, and even more preferably 2°C / min or more, in order to efficiently generate molybdenum trioxide vapor. For example, the heating rate can be 100°C / min or less, preferably 50°C / min or less, and more preferably 10°C / min or less.

[0071] There are no particular restrictions on the calcination time for calcining the raw materials in the vaporization process. For example, it can be 1 minute or more, preferably 1 minute to 30 hours, and may also be 10 minutes to 25 hours, or 100 minutes to 20 hours.

[0072] The pressure inside the firing furnace 2 when firing the raw materials in the vaporization process is not particularly limited and may be positive or reduced pressure. In the vaporization process, it is preferable to reduce the pressure inside the firing furnace 2 so that the vaporized molybdenum trioxide vapor can be easily discharged from the firing furnace 2 into the cooling pipe 3.

[0073] The calcination of the raw materials in the calcination furnace 2 is preferably carried out in a calcination furnace 2 with a pressure of -5000 Pa to -800 Pa. The pressure inside the calcination furnace 2 is more preferably -3000 Pa to -900 Pa, and even more preferably -2000 Pa to -1000 Pa. A pressure of -5000 Pa or higher inside the calcination furnace 2 is preferable because it does not require excessive airtightness and mechanical strength for the calcination furnace 2, and the manufacturing cost of the molybdenum trioxide powder production apparatus 1 can be suppressed. On the other hand, if the pressure inside the calcination furnace 2 is -800 Pa or lower, the amount of outside air introduced per unit time into the cooling pipe 3 increases, making it easier to obtain molybdenum trioxide powder with a sufficiently small particle size and a sufficiently large specific surface area as measured by the BET method.

[0074] In this embodiment, the pressure inside the firing furnace 2 when firing the raw materials means the average value of the pressure inside the firing furnace 2 from the time the temperature inside the firing furnace 2 reaches the firing temperature and suction by the exhaust device 8 is started until the firing of the raw materials is completed.

[0075] In the molybdenum trioxide powder manufacturing apparatus 1 shown in Figure 1, the pressure inside the calcination furnace 2 is determined by the suction strength from the cooling pipe 3, which is drawn in by the exhaust air device 8 via the first dust collector 4a or the second dust collector 4b. Therefore, in the molybdenum trioxide powder manufacturing method of this embodiment, the pressure inside the calcination furnace 2 when calcining the raw material can be adjusted by the suction capacity of the exhaust air device 8. By controlling the pressure inside the calcination furnace 2 with the exhaust air device 8, the specific surface area of ​​the manufactured molybdenum trioxide powder, as measured by the BET method, can be controlled.

[0076] (Powdering Process) In the molybdenum trioxide powder manufacturing method of this embodiment, a powdering process is performed in which the molybdenum trioxide vapor formed in the vaporization process is cooled by outside air blown into the cooling pipe 3 to form a powder. In the molybdenum trioxide powder manufacturing method of this embodiment, the first powdering process and the second powdering process described below are performed alternately by switching the three-way valve 43 and the three-way valve 53 shown in Figure 1 during the powdering process.

[0077] The first pulverization step, as shown in Figure 1, involves connecting a first dust collector 4a to the cooling pipe 3 and using an exhaust fan 8 to discharge the gas inside the cooling pipe 3 via the first dust collector 4a, thereby supplying outside air into the cooling pipe 3. The second pulverization step, as shown in Figure 1, involves connecting a second dust collector 4b to the cooling pipe 3 and using an exhaust fan 8 to discharge the gas inside the cooling pipe 3 via the second dust collector 4b, thereby supplying outside air into the cooling pipe 3.

[0078] In order to alternate between the first powdering process and the second powdering process, the timing for switching the three-way valve 43 and the three-way valve 53 can be appropriately determined according to the amount of molybdenum trioxide powder produced per unit time, the particle size of the produced molybdenum trioxide powder, and the types of filters provided in the first dust collector 4a and the second dust collector 4b.

[0079] The first pulverization process and the second pulverization process are preferably performed alternately by switching the three-way valve 43 and the three-way valve 53 shown in Figure 1 at predetermined time intervals. For example, it is preferable to switch the three-way valve 43 and the three-way valve 53 every 5 to 300 minutes. The switching of the three-way valve 43 and the three-way valve 53 may be performed using, for example, a known control device.

[0080] In the method for producing molybdenum trioxide powder of this embodiment, if the powdering step is a process in which the first powdering step and the second powdering step are performed alternately multiple times in that order, it is preferable to include the following first discharge step and second discharge step. The first discharge step is a step of discharging the molybdenum trioxide powder recovered by the first dust collector 4a from the first dust collector 4a while the second powdering step is being performed. The second discharge step is a step of discharging the molybdenum trioxide powder recovered by the second dust collector 4b from the second dust collector 4b while the second and subsequent first powdering steps are being performed.

[0081] As a method for discharging molybdenum trioxide powder from the first dust collector 4a and the second dust collector 4b, known methods can be used, such as removing molybdenum trioxide powder captured from filters installed in the first dust collector 4a and the second dust collector 4b, or replacing the filters installed in the first dust collector 4a and the second dust collector 4b.

[0082] In the first and second powdering processes, the amount of outside air introduced per unit time into the cooling pipe 3 is 4.0 m³. ３ / min ~ 20m ３ It is preferable that it be / min, and 4.5m ３ / min ~ 10m ３ It is more preferable that it be / min. The amount of outside air introduced per unit time into the cooling pipe 3 is 4.0 m³. ３ If the airflow velocity is 20 m / min or higher, the cooling rate of molybdenum trioxide vapor increases, making it easier to obtain molybdenum trioxide powder with a sufficiently small particle size and a sufficiently large specific surface area as measured by the BET method. On the other hand, if the gas blowing velocity is 20 m / min or higher, ３If the value is less than or equal to / min, the airflow speed can be easily adjusted at low cost without using a manufacturing apparatus equipped with an exhaust device 8 that has excessive suction capacity, and molybdenum trioxide powder with a sufficiently large specific surface area as measured by the BET method can be produced.

[0083] In this embodiment, the amount of outside air introduced per unit time into the cooling pipe 3 is the average value of the amount of outside air introduced per unit time into the cooling pipe 3 while the raw materials are being fired in the firing furnace 2 and suction is being performed by the exhaust device 8, and means the average value of the amount of outside air introduced in the first powdering process and the amount of outside air introduced in the second powdering process.

[0084] In the first and second powdering processes, the amount of outside air introduced per unit time into the cooling pipe 3 is determined by the suction strength of the exhaust device 8 shown in Figure 1, which draws the cooling pipe 3 through the first dust collector 4a or the second dust collector 4b. Therefore, in the molybdenum trioxide powder manufacturing method of this embodiment, the amount of outside air introduced per unit time into the cooling pipe 3 can be adjusted by the suction capacity of the exhaust device 8. By controlling the amount of outside air introduced per unit time into the cooling pipe 3 by the exhaust device 8, the specific surface area of ​​the manufactured molybdenum trioxide powder, as measured by the BET method, can be controlled. In the molybdenum trioxide powder manufacturing method of this embodiment, the temperature of the outside air introduced into the cooling pipe 3 is usually 0°C to 50°C, but may also be 15°C to 35°C or 15°C to 25°C.

[0085] The cooling rate of molybdenum trioxide vapor in the first and second powdering steps is not particularly limited, but when the pressure inside the firing furnace 2 is within the above range and the amount of outside air introduced per unit time into the cooling pipe 3 is within the above range, it can be, for example, in the range of 100°C / s to 100,000°C / s, and preferably in the range of 2,000°C / s to 50,000°C / s.

[0086] When the cooling rate of molybdenum trioxide vapor is 100°C / s or higher, it becomes easier to obtain molybdenum trioxide powder with a sufficiently small particle size and a sufficiently large specific surface area as measured by the BET method. Furthermore, when the cooling rate of molybdenum trioxide vapor is 100,000°C / s or lower, it can be easily adjusted by setting the pressure inside the firing furnace 2 within the above range and the amount of outside air introduced per unit time into the cooling pipe 3 within the above range.

[0087] In the first and second powdering processes, the concentration of powdered molybdenum trioxide in the cooling pipe 3 is, for example, 0.01 g / m³. ３ ~5g / m ３ It can be in the range of 0.01 g / m ３ ~3g / m ３ It is preferable that the concentration of powdered molybdenum trioxide in the cooling pipe 3 is 5 g / m³. ３ The following conditions make it easier to obtain molybdenum trioxide powder with a sufficiently small particle size and a sufficiently large specific surface area as measured by the BET method: A concentration of powdered molybdenum trioxide in the cooling pipe 3 is 0.01 g / m³. ３ With the above conditions met, molybdenum trioxide powder can be produced efficiently.

[0088] In this embodiment, the concentration of powdered molybdenum trioxide in the cooling pipe 3 is defined as the amount of powdered material per unit time [g / min] in the cooling pipe 3 multiplied by the ambient air flow rate [m³]. ３ This means the number is obtained by dividing by " / min".

[0089] The molybdenum trioxide powder manufacturing apparatus 1 of this embodiment includes a calcination furnace 2 for calcining and vaporizing a raw material containing a molybdenum oxide precursor compound, a cooling pipe 3 connected to the calcination furnace 2 for cooling and pulverizing the molybdenum trioxide vapor vaporized in the calcination furnace 2, and a first dust collector 4a and a second dust collector 4b for recovering the pulverized molybdenum trioxide powder, which are alternately connected to the cooling pipe 3, and an exhaust device 8 connected to the first dust collector 4a and the second dust collector 4b. The exhaust device 8 discharges the gas in the cooling pipe 3 via the first dust collector 4a or the second dust collector 4b, thereby blowing outside air into the cooling pipe 3.

[0090] Therefore, in the molybdenum trioxide powder manufacturing apparatus 1 of this embodiment, for example, even if the filter installed in the first dust collector 4a becomes clogged with molybdenum trioxide powder recovered by the first dust collector 4a connected to the cooling pipe 3 and exhaust device 8, the reduction in the amount of outside air introduced per unit time into the cooling pipe 3, which is caused by the clogging of the filter installed in the first dust collector 4a, can be eliminated by switching the three-way valve 43 and the three-way valve 53 to connect the cooling pipe 3 and exhaust device 8 to the second dust collector 4b.

[0091] Therefore, the molybdenum trioxide powder manufacturing apparatus 1 of this embodiment can stably supply a sufficiently large amount of outside air into the cooling pipe 3, compared to, for example, a manufacturing apparatus with only one dust collector. Thus, the molybdenum trioxide powder manufacturing apparatus 1 of this embodiment can be suitably used when manufacturing the molybdenum trioxide powder of this embodiment, which has a small particle size and a large specific surface area as measured by the BET method.

[0092] The method for producing molybdenum trioxide powder of this embodiment includes a vaporization step in which a raw material containing a molybdenum oxide precursor compound is calcined and vaporized in a calcination furnace 2 to form molybdenum trioxide vapor, and a powdering step in which the molybdenum trioxide vapor is cooled and powdered by outside air blown into a cooling pipe 3. In the powdering step, a first powdering step is performed alternately, in which a first dust collector 4a is connected to the cooling pipe 3 and the gas in the cooling pipe 3 is discharged through the first dust collector 4a by an exhaust fan 8, thereby blowing outside air into the cooling pipe 3, and a second powdering step is performed alternately, in which a second dust collector 4b is connected to the cooling pipe 3 and the gas in the cooling pipe 3 is discharged through the second dust collector 4b by an exhaust fan 8, thereby blowing outside air into the cooling pipe 3.

[0093] Therefore, in the molybdenum trioxide powder manufacturing method of this embodiment, for example, even if the filter installed in the first dust collector 4a becomes clogged in the first powdering step, the reduction in the amount of outside air introduced per unit time into the cooling pipe 3, which is caused by the clogging of the filter installed in the first dust collector 4a, can be eliminated by switching the three-way valve 43 and the three-way valve 53 to start the second powdering step.

[0094] Therefore, according to the molybdenum trioxide powder manufacturing method of this embodiment, a sufficiently large amount of outside air can be stably supplied into the cooling pipe 3. Thus, by using the molybdenum trioxide powder manufacturing method of this embodiment, it is possible to manufacture molybdenum trioxide powder of this embodiment with a small particle size and a large specific surface area as measured by the BET method.

[0095] Although embodiments of the present invention have been described in detail above with reference to the drawings, the configurations and combinations thereof in each embodiment are merely examples, and additions, omissions, substitutions, and other modifications to the configurations are possible without departing from the spirit of the present invention.

[0096] (Other examples) In the molybdenum trioxide powder manufacturing apparatus 1 of this embodiment shown in Figure 1, the case where there is only one exhaust device 8 has been described as an example. However, the molybdenum trioxide powder manufacturing apparatus of the present invention may have two exhaust devices: an exhaust device connected to a first dust collector by a first suction pipe, and an exhaust device connected to a second dust collector by a second suction pipe. In this case, the suction pipe 50 and the three-way valve 53 in the molybdenum trioxide powder manufacturing apparatus 1 of this embodiment shown in Figure 1 are unnecessary.

[0097] Furthermore, the molybdenum trioxide powder manufacturing apparatus of the present invention may have a known external cooling device (indicated by reference numeral 9 in Figure 1) for cooling the cooling pipes from the outside, if necessary. When molybdenum trioxide powder is manufactured using a manufacturing apparatus having an external cooling device 9, the cooling rate of molybdenum trioxide vapor inside the cooling pipes can be made even faster by cooling the cooling pipes from the outside. As a result, molybdenum trioxide powder with a larger specific surface area can be easily manufactured.

[0098] In the molybdenum trioxide powder manufacturing apparatus 1 of this embodiment shown in Figure 1, a preferred example of the molybdenum trioxide powder manufacturing apparatus 1 is described as having two dust collectors, a first dust collector 4a and a second dust collector 4b. However, the dust collectors in the molybdenum trioxide powder manufacturing apparatus of the present invention may be any multiple dust collectors that are interchangeably connected to the cooling pipes, and may have three or more dust collectors. The molybdenum trioxide powder manufacturing apparatus of the present invention is preferable to have two dust collectors, a first dust collector 4a and a second dust collector 4b, because it requires less space for installing dust collectors.

[0099] If the molybdenum trioxide powder manufacturing apparatus of the present invention has three or more dust collectors, for example, if a first dust collector selected from the multiple dust collectors is connected to a cooling pipe to manufacture molybdenum trioxide powder, and the filter installed in the first dust collector becomes clogged, then any second dust collector other than the first dust collector selected from the multiple dust collectors can be connected to the cooling pipe to manufacture molybdenum trioxide powder. This eliminates the reduction in the amount of outside air introduced per unit time into the cooling pipe caused by the clogging of the filter installed in the first dust collector.

[0100] Subsequently, if the filter installed in the second dust collector becomes clogged, any dust collector other than the second dust collector, selected from among multiple dust collectors, can be connected to the cooling pipe to produce molybdenum trioxide powder. This eliminates the reduction in the amount of outside air introduced per unit time into the cooling pipe caused by the clogging of the filter installed in the second dust collector.

[0101] The present invention will be described in more detail below with reference to examples. However, the present invention is not limited to the following examples.

[0102] [Example 1] Using the molybdenum trioxide powder manufacturing apparatus 1 shown in Figure 1, the molybdenum trioxide powder of Example 1 was manufactured by the method described below. (Vaporization process) The powder molybdenum trioxide (MoO) is a molybdenum oxide precursor compound. ３) (manufactured by Nippon Inorganic Chemical Industry Co., Ltd.) and aluminum hydroxide (Al(OH) powder, which is a metal oxide other than molybdenum oxide precursor compounds. ３ Raw materials containing ) (manufactured by Nippon Light Metal Co., Ltd.) in the proportions shown in Table 1 were prepared.

[0103] Next, the above raw materials were subjected to a vaporization process to form molybdenum trioxide vapor by firing them in a firing furnace 2 under the following conditions: firing temperature of 1100°C, firing time of 10 hours, heating rate in the firing furnace 2 to the firing temperature of 5°C / min, and pressure in the firing furnace 2 of -1000 Pa as shown in Table 1.

[0104]

[0105] The "Pressure inside the firing furnace" shown in Table 1 is the average value of the pressure inside the firing furnace 2 from the time the temperature inside the firing furnace 2 reaches the firing temperature shown in Table 1 and suction by the exhaust fan 8 is started until the firing of the raw materials is completed. The pressure inside the firing furnace was measured using a pressure gauge (product name: Manostar (manufactured by Yamamoto Electric Works)) installed inside the firing furnace. The suction capacity of the exhaust fan 8 was adjusted so that the pressure inside the firing furnace was the value shown in Table 1 when suction by the exhaust fan 8 was started. After that, the suction capacity of the exhaust fan 8 was maintained at a constant level.

[0106] Next, the molybdenum trioxide vapor formed in the vaporization process was cooled and pulverized using 25°C outside air blown into the cooling pipe 3 at the outside air intake rate shown in Table 1. As part of the pulverization process, the first and second pulverization processes described below were performed alternately 16 times each by switching the three-way valves 43 and 53 shown in Figure 1 to obtain the molybdenum trioxide powder of Example 1.

[0107] The "amount of outside air introduced" shown in Table 1 is the average amount of outside air introduced per unit time into the cooling pipe 3 while the raw materials are being fired in the firing furnace 2 and suction is being performed by the exhaust device 8. It is the average of the amount of outside air introduced in the first powdering process and the amount of outside air introduced in the second powdering process. The amount of outside air introduced was measured using a measuring device (product name: in-line vortex flow meter: manufactured by Azbil) installed in the cooling pipe 3.

[0108] In the first pulverization process, as shown in Figure 1, a first dust collector 4a was connected to the cooling pipe 3, and outside air was blown into the cooling pipe 3 by exhausting the gas inside the cooling pipe 3 via the first dust collector 4a using the exhaust device 8. In the second pulverization process, as shown in Figure 1, a second dust collector 4b was connected to the cooling pipe 3, and outside air was blown into the cooling pipe 3 by exhausting the gas inside the cooling pipe 3 via the second dust collector 4b using the exhaust device 8.

[0109] Furthermore, while the second powdering process was being carried out, a first discharge process was performed in which the molybdenum trioxide powder recovered by the first dust collector 4a was discharged from the first dust collector 4a. Also, while the second and subsequent first powdering processes were being carried out, a second discharge process was performed in which the molybdenum trioxide powder recovered by the second dust collector 4b was discharged from the second dust collector 4b. As a method for discharging the molybdenum trioxide powder from the first dust collector 4a and the second dust collector 4b, a method of replacing the filters (mesh size 10 μm) installed in the first dust collector 4a and the second dust collector 4b was used.

[0110] To alternate between the first and second powdering processes, the switching timing for the three-way valves 43 and 53 was set to every 30 minutes. Bag filter switching valves (product name, 125A air-driven popped valve; manufactured by Amano Corporation) were used as the three-way valves 43 and 53, and the switching was performed by air drive.

[0111] [Example 2] The powdered molybdenum trioxide (MoO) used as a molybdenum oxide precursor compound in Example 1. ３ ) and aluminum hydroxide (Al(OH)) as a metal oxide other than molybdenum oxide precursor compounds. ３ Except for using the ratios shown in Table 1, the molybdenum trioxide powder of Example 2 was obtained in the same manner as in Example 1.

[0112] [Example 3] The powdered molybdenum trioxide (MoO) used as a molybdenum oxide precursor compound in Example 1. ３ ) and aluminum hydroxide (Al(OH)) as a metal oxide other than molybdenum oxide precursor compounds. ３Except for using the ingredients shown in Table 1 in the proportions shown in Table 1 and using the calcination temperature shown in Table 1, the molybdenum trioxide powder of Example 3 was obtained in the same manner as in Example 1.

[0113] [Example 4] The powdered molybdenum trioxide (MoO) used as a molybdenum oxide precursor compound in Example 1. ３ ) and aluminum oxide powder as a metal oxide other than molybdenum oxide precursor compounds (Al ２ O ３ Except for using the ratios shown in Table 1, the molybdenum trioxide powder of Example 4 was obtained in the same manner as in Example 1.

[0114] [Examples 5 and 6] The powdered molybdenum trioxide (MoO) used as a molybdenum oxide precursor compound in Example 1 ３ ) and aluminum oxide powder as a metal oxide other than molybdenum oxide precursor compounds (Al ２ O ３ Except for using the ratios shown in Table 1 and the firing temperature shown in Table 1, the molybdenum trioxide powders of Examples 5 and 6 were obtained in the same manner as in Example 1.

[0115] [Example 7] The powdered molybdenum trioxide (MoO) used as a molybdenum oxide precursor compound in Example 1. ３ ) and magnesium aluminate (MgAl) as a metal oxide other than molybdenum oxide precursor compounds. ２ O ４ Except for using the ratios shown in Table 1, the molybdenum trioxide powder of Example 7 was obtained in the same manner as in Example 1.

[0116] [Comparative Example 1] In the powdering process, the three-way valves 43 and 53 shown in Figure 1 were not switched, and only the first powdering process was performed for 600 minutes. In addition, the pressure inside the firing furnace in Comparative Example 1 was set to -400 Pa at the start of suction by the exhaust fan 8, and the suction capacity of the exhaust fan 8 was adjusted. After that, the suction capacity of the exhaust fan 8 was maintained at a constant level. Thus, molybdenum trioxide powder was produced in the same manner as in Example 1, except that the pressure inside the firing furnace 2 and the amount of outside air introduced were as shown in Table 1, and the molybdenum trioxide powder of Comparative Example 1 was obtained.

[0117] For the molybdenum trioxide powders obtained in this manner from Examples 1 to 7 and Comparative Example 1, the specific surface area measured by the BET method and the median diameter D determined by the dynamic light scattering method were determined. ５０ The purity of the molybdenum trioxide powder and the crystal structure of molybdenum trioxide were measured using the methods described below. The results are shown in Table 1.

[0118] [Method for measuring specific surface area using the BET method] The amount of nitrogen gas adsorbed by molybdenum trioxide powder was measured using the BET method with a specific surface area meter (Microtrac Bell, BELSORP-mini). From the measurement results, the surface area per gram of molybdenum trioxide powder was calculated, and the specific surface area (m²) of the molybdenum trioxide powder was determined. ２ ( / g) was used.

[0119] [Median diameter D] ５０ [Measurement Method] An ethanol solution prepared by adding 0.1 g of molybdenum trioxide powder to 10 cc of ethanol was subjected to sonication in an ice bath for 4 hours. The sonicated ethanol solution was then adjusted with ethanol to a concentration within the measurable range of a dynamic light scattering particle size distribution analyzer (MicrotracBEL Nanotrac Wave II) to obtain a measurement sample. Using this measurement sample, the particle size distribution in the range of 0.0001 to 10 μm was measured using a dynamic light scattering particle size distribution analyzer, and the median diameter D was measured. ５０ The result was calculated.

[0120] [Molybdenum trioxide (MoO ３[Purity of the powder] Elemental analysis of molybdenum trioxide powder was performed using an X-ray fluorescence analyzer (XRF analyzer) (product name: Primus IV, manufactured by Rigaku Corporation). The purity of the molybdenum trioxide powder was calculated using the results.

[0121] [Molybdenum trioxide (MoO ３ [Crystal structure of] The crystal structure of molybdenum trioxide powder was analyzed using an X-ray diffraction (XRD) chart obtained with an X-ray diffraction (XRD) instrument (product name: Smart lab, manufactured by Rigaku Corporation). From the results, it was confirmed whether or not the molybdenum trioxide powder contains a β crystal structure.

[0122] As shown in Table 1, the molybdenum trioxide powders of Examples 1 to 7 had a larger specific surface area measured by the BET method compared to the molybdenum trioxide powder of Comparative Example 1. Furthermore, as shown in Table 1, the molybdenum trioxide powders of Examples 1 to 7 had a larger median diameter D compared to the molybdenum trioxide powder of Comparative Example 1. ５０ But it was small.

[0123] This is because, in Comparative Example 1, the filter installed in the first dust collector became clogged, preventing the pressure inside the firing furnace 2 from being lowered below -400 Pa, resulting in a higher pressure inside the firing furnace 2 compared to Examples 1 and 2. As a result, it is presumed that in Comparative Example 1, the amount of outside air introduced was less compared to Examples 1 and 2, and the cooling rate of molybdenum trioxide vapor was slower.

[0124] Furthermore, compared to Example 1, the molybdenum trioxide powder of Example 2, which used less raw material, had a larger specific surface area measured by the BET method and a larger median diameter D than the molybdenum trioxide powder of Example 1. ５０ The value was small. This is presumed to be because, in Example 2, the content of molybdenum oxide precursor compound and metal oxides other than the molybdenum oxide precursor compound in the raw materials was small, resulting in a lower density of molybdenum trioxide molecules in the cooling pipe 3 and a faster cooling rate of molybdenum trioxide vapor.

[0125] Furthermore, the molybdenum trioxide powder of Example 3, which was fired at a lower firing temperature compared to Example 2, had a larger specific surface area and median diameter D compared to the molybdenum trioxide powder of Example 2, as measured by the BET method. ５０ But it was small.

[0126] In addition, as metal oxides other than molybdenum oxide precursor compounds, aluminum oxide (Al ２ O ３ In Examples 4 to 6, which used the above method, the lower the content of the molybdenum oxide precursor compound in the raw material, the larger the specific surface area measured by the BET method and the larger the median diameter D ５０ It became smaller.

[0127] Furthermore, in the process of producing molybdenum trioxide powder in Example 1, the molybdenum trioxide powdered in the cooling pipe 3 was recovered at the timing of switching between the first and second powdering processes (every 30 minutes) from the start of the first powdering process, and the mass of the recovered molybdenum trioxide powder was measured.

[0128] Using these results, the amount of molybdenum trioxide powder pulverized in the cooling pipe 3 per minute (recovery amount) [g / min] and the amount of outside air introduced (outside air flow rate) [m³] were calculated. ３ The concentration of powdered molybdenum trioxide in the cooling pipe 3 was determined from the value of " / min". Specifically, the concentration of powdered molybdenum trioxide in the cooling pipe 3 is the value obtained by dividing the amount of molybdenum trioxide powder per minute (recovery amount) by the amount of outside air introduced.

[0129] Table 2 shows the results of the recovery of molybdenum trioxide powder, the amount of molybdenum trioxide powder per minute, the amount of outside air introduced, and the concentration of the pulverized molybdenum trioxide, arranged in order from the shortest elapsed time since the start of the molybdenum trioxide powder production process in Example 1. In addition, in the molybdenum trioxide powder production process of Example 1, the pulverized molybdenum trioxide in the cooling pipe 3 was recovered every 30 minutes, and the specific surface area of ​​the recovered molybdenum trioxide powder measured by the BET method was investigated using the method described above. The results are shown in Table 2.

[0130]

[0131] As shown in Table 2, in Example 1, it was confirmed that the lower the concentration of molybdenum trioxide powdered in the cooling pipe 3, the larger the specific surface area of ​​the recovered molybdenum trioxide powder measured by the BET method.

[0132] Furthermore, in the process of producing molybdenum trioxide powder in Example 4, the molybdenum trioxide pulverized in the cooling pipe 3 was collected every 30 minutes, and the concentration of the collected molybdenum trioxide powder and the specific surface area measured by the BET method were investigated in the same manner as in Example 1. Figure 2 shows the relationship between the concentration of molybdenum trioxide pulverized in the cooling pipe 3 and the specific surface area of ​​the collected molybdenum trioxide powder measured by the BET method in Example 4.

[0133] As shown in Figure 2, in Example 4, it was confirmed that the lower the concentration of molybdenum trioxide powdered in the cooling pipe 3, the larger the specific surface area of ​​the recovered molybdenum trioxide powder measured by the BET method.

[0134] According to the present invention, it is possible to provide molybdenum trioxide powder that has a larger specific surface area as measured by the BET method and can be suitably used as a precursor of molybdenum sulfide.

[0135] 1. Manufacturing equipment 2. Firing furnace 3. Cooling piping 4a. First dust collector 4b. Second dust collector 5. Exhaust port 6. Opening adjustment damper 7. Observation window 8. Air exhaust device 9. External cooling device

Claims

1. The specific surface area measured by the BET method is 100 m². ２ / g or more 500m ２ Molybdenum trioxide powder with a concentration of less than / g.

2. Median diameter D determined by dynamic light scattering method ５０ The molybdenum trioxide powder according to claim 1, wherein the wavelength is 5 nm or more and 1000 nm or less.

3. The molybdenum trioxide powder according to claim 1, wherein the purity is 99% by mass or higher.

4. The molybdenum trioxide powder according to claim 1, comprising molybdenum trioxide with a β-crystalline structure.

5. A molybdenum trioxide powder manufacturing apparatus used for manufacturing molybdenum trioxide powder according to any one of claims 1 to 4, comprising: a calcination furnace for calcining and vaporizing a raw material containing a molybdenum oxide precursor compound; a cooling pipe connected to the calcination furnace for cooling and pulverizing the molybdenum trioxide vapor vaporized in the calcination furnace; a plurality of dust collectors for recovering the pulverized molybdenum trioxide powder, which are interchangeably connected to the cooling pipe; and an exhaust device connected to the plurality of dust collectors, wherein the exhaust device discharges the gas in the cooling pipe through one dust collector selected from the plurality of dust collectors, thereby blowing outside air into the cooling pipe.

6. The apparatus for producing molybdenum trioxide powder according to claim 5, wherein the plurality of dust collectors consist of a first dust collector and a second dust collector, and the first dust collector and the second dust collector are alternately connected to the cooling pipe.

7. A method for producing molybdenum trioxide powder using the molybdenum trioxide powder production apparatus described in claim 5, comprising: a vaporization step of firing and vaporizing a raw material containing a molybdenum oxide precursor compound in the firing furnace to form molybdenum trioxide vapor; and a powdering step of cooling the molybdenum trioxide vapor with outside air blown into the cooling pipe to form powder, wherein the powdering step comprises: a first powdering step of connecting a first dust collector selected from the plurality of dust collectors to the cooling pipe and blowing outside air into the cooling pipe by exhausting the gas in the cooling pipe via the first dust collector with the exhaust device; and a second powdering step of connecting a second dust collector other than the first dust collector selected from the plurality of dust collectors to the cooling pipe and blowing outside air into the cooling pipe by exhausting the gas in the cooling pipe via the second dust collector with the exhaust device.

8. The method for producing molybdenum trioxide powder according to claim 7, wherein the first dust collector and the second dust collector are alternately connected to the cooling pipe, and in the powdering process, the first powdering process and the second powdering process are performed alternately at predetermined intervals.

9. The method for producing molybdenum trioxide powder according to claim 8, wherein the powdering step is a step of performing the first powdering step and the second powdering step alternately multiple times in that order, and includes a first discharge step of discharging the molybdenum trioxide powder recovered by the first dust collector from the first dust collector while the second powdering step is being performed, and a second discharge step of discharging the molybdenum trioxide powder recovered by the second dust collector from the second dust collector while the second and subsequent first powdering steps are being performed.

10. The method for producing molybdenum trioxide powder according to claim 7, wherein in the vaporization step, the raw material is calcined at a calcination temperature of 800°C or more and 1100°C or less.

11. The method for producing molybdenum trioxide powder according to claim 7, wherein the raw material contains a metal oxide other than the molybdenum oxide precursor compound in an amount of 50% by mass or more and 400% by mass or less, based on 100% by mass of the molybdenum oxide precursor compound.

12. The method for producing molybdenum trioxide powder according to claim 11, wherein the metal oxide is one or more selected from aluminum hydroxide, boehmite, and alumina.

13. In the first and second powdering steps, the amount of outside air introduced per unit time into the cooling pipe is 4.0 m³. ３ / min ~ 20m ３ A method for producing molybdenum trioxide powder according to claim 7, wherein the amount is / min.

14. A method for producing molybdenum trioxide powder according to claim 7, wherein the raw material is calcined in the calcination furnace at a pressure of -5000 Pa to -800 Pa.

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