Molybdenum trioxide powder and method for producing the same

Abstract

A molybdenum trioxide powder, which contains an aggregate of primary particles comprising a crystal structure of molybdenum trioxide, the crystal structure comprising α-crystals having an average crystallite size of 50 nm or less. The median particle diameter D50 of the primary particles, which is obtained by a dynamic light scattering method, is 2000 nm or less. 50 is 2000 nm or less.

Description

TECHNICAL FIELD

[0001] The present application relates to a molybdenum trioxide powder and a method for producing the same.

[0002] This application is based on Japanese Priority Application No. 2021-050489 filed on March 24, 2021, the content of which is incorporated herein by reference. BACKGROUND

[0003] Patent Literature 1 discloses a manufacturing apparatus of a metal oxide based on a flux evaporation method and a manufacturing method of the above metal oxide, and in the case where a molybdenum compound is used as a flux, a powderized molybdenum trioxide can be recovered.

[0004] In addition, Patent Literature 2 discloses a manufacturing method of a nanocrystalline molybdenum mixed oxide and an application of the molybdenum mixed oxide as a catalyst for chemical conversion.

[0005] PRIOR ART DOCUMENTS

[0006] PATENT LITERATURE

[0007] Patent Literature 1: International Publication No. 2018 / 003481

[0008] Patent Literature 2: Japanese Patent Application Laid-Open No. 2011-516378 SUMMARY

[0009] The problem to be solved by the invention

[0010] In the case where a molybdenum trioxide powder is used as a precursor of molybdenum sulfide, a commercially available molybdenum trioxide powder has a difficulty in terms of sulfidation reactivity. In addition, in the case where the purity of molybdenum trioxide is high, molybdenum sulfide having a high purity can be obtained, and in the case where the purity is low, a sulfide derived from impurities can be generated. Generally, sulfides other than molybdenum sulfide have a poor stability and are easily decomposed by acid, water, and the like to generate hydrogen sulfide having a high toxicity. Therefore, from the viewpoint of storage stability (generation of hydrogen sulfide), a very high purity is required.

[0011] The present application has been made in view of the above circumstances, and an object is to provide a molybdenum trioxide powder suitable as a precursor of molybdenum sulfide and a method for producing the same.

[0012] The solution to the problem

[0013] The present application includes the following modes.

[0014] (1) A molybdenum trioxide powder containing an aggregate of primary particles including a crystal structure of molybdenum trioxide, the crystal structure including an α-crystal having an average crystallite size of 50 nm or less, and a median particle diameter D50 of the primary particles, which is obtained by a dynamic light scattering method, being 2000 nm or less. 50 is 2000 nm or less.

[0015] (2) The molybdenum trioxide powder according to (1) above, wherein the content of MoO3 as determined by fluorescence X-ray (XRF) is 99.5% by mass or more relative to the total weight of the molybdenum trioxide powder.

[0016] (3) The molybdenum trioxide powder described in (1) or (2) above has a specific surface area of ​​10 m² as determined by the BET method. 2 / g or more.

[0017] (4) The molybdenum trioxide powder according to any one of (1) to (3) above, wherein the crystal structure further comprises β crystals with an average crystallite size of 50 nm or less.

[0018] (5) According to the molybdenum trioxide powder described in (4) above, in the spectrum obtained by powder X-ray diffraction (XRD) using Cu-Kα rays as the X-ray source, the ratio of the peak intensity of the (011) plane of the β crystal belonging to MoO3 to the peak intensity of the (021) plane of the α crystal belonging to MoO3 (β(011) / α(021)) is 0.1 or more.

[0019] (6) The molybdenum trioxide powder according to (5) above, wherein in the spectrum obtained by powder X-ray diffraction (XRD) using Cu-Kα rays as the X-ray source, the ratio of the peak intensity of the (011) plane of the β crystal belonging to MoO3 to the peak intensity of the (021) plane of the α crystal belonging to MoO3 (β(011) / α(021)) is 10.0 or less.

[0020] (7) The molybdenum trioxide powder according to any one of (1) to (6) above, wherein the shape of the primary particles is a strip or sheet with a thickness at the nanometer level.

[0021] (8) A method for manufacturing molybdenum trioxide powder according to any one of (1) to (7) above, comprising the following steps: vaporizing a molybdenum oxide precursor compound to form molybdenum trioxide vapor, and cooling the molybdenum trioxide vapor.

[0022] (9) The method for manufacturing molybdenum trioxide powder according to (8) above includes the following steps: calcining a raw material mixture containing a molybdenum oxide precursor compound and a metal compound other than the molybdenum oxide precursor compound to vaporize the molybdenum oxide precursor compound and form molybdenum trioxide vapor, wherein the ratio of the metal compound to the raw material mixture is 95% by mass or less when converted to oxides.

[0023] Effects of the invention

[0024] According to the present invention, molybdenum trioxide powder suitable as a precursor of molybdenum sulfide and a method thereof can be provided. Attached Figure Description

[0025] Figure 1 A schematic diagram illustrating an example of an apparatus used to manufacture molybdenum trioxide particles, which are the raw materials for molybdenum sulfide particles.

[0026] Figure 2A The image shows the XRD pattern of Example 1, the position diagram of the α crystal peak in the top row, and the position diagram of the β crystal peak in the middle row below it.

[0027] Figure 2B The XRD pattern of Comparative Example 1 and the position diagram of the α crystal peaks in the top row are shown.

[0028] Figure 3A This is an analysis diagram of the crystallite size and diffraction intensity of Example 1.

[0029] Figure 3B The diagram shows the analysis of crystallite size and diffraction intensity for Comparative Example 1. Detailed Implementation

[0030] The embodiments of the present invention will be described in detail below with reference to the accompanying drawings.

[0031] <Molybdenum trioxide powder>

[0032] The molybdenum trioxide powder of this embodiment comprises an aggregate of primary particles with a crystal structure containing molybdenum trioxide. This crystal structure includes α-crystals with an average crystallite size of 50 nm or less. The median particle size D of these primary particles is determined by dynamic light scattering. 50 Below 2000nm.

[0033] The molybdenum trioxide powder of this embodiment comprises an aggregate of primary particles, wherein the primary particles have a crystalline structure of molybdenum trioxide, and the median particle size D of the primary particles is determined by dynamic light scattering method. 50 The crystal size is below 2000 nm. Furthermore, the crystal structure described above includes α-crystals with an average crystallite size of 50 nm or less. Therefore, the molybdenum trioxide powder of this embodiment exhibits better reactivity with sulfur compared to conventional molybdenum trioxide powder.

[0034] In the molybdenum trioxide powder of this embodiment, the median particle size D of the primary particles, determined by dynamic light scattering, is... 50 Preferably, the wavelength is 10nm or larger and 2000nm or smaller, more preferably 10nm or larger and 500nm or smaller, and even more preferably 10nm or larger and 200nm or smaller.

[0035] Median particle size D of primary particles 50Within the aforementioned preferred range, the reactivity of molybdenum trioxide powder with sulfur tends to improve. The median particle size D of the primary particles of molybdenum trioxide powder... 50 For example, it can be calculated from the cumulative particle size distribution of a volume reference measured using a dynamic light scattering particle size distribution measuring device.

[0036] In this embodiment, the average particle size of the primary particles of molybdenum trioxide powder refers to the average primary particle size of 50 randomly selected primary particles when the major axis (Ferret diameter of the longest observed part) and minor axis (shorter Ferret diameter in the direction perpendicular to the Ferret diameter of the longest part) of the particles constituting the smallest unit of the aggregate (i.e., primary particles) in the two-dimensional image of molybdenum trioxide powder are photographed using a transmission electron microscope (TEM) or a scanning electron microscope (SEM), and their average value is taken as the primary particle size.

[0037] In this embodiment, the average crystallite size of the α crystals contained in the crystal structure of molybdenum trioxide is preferably 5 nm or more and 50 nm or less, more preferably 5 nm or more and 45 nm or less, even more preferably 10 nm or more and 40 nm or less, and particularly preferably 10 nm or more and 35 nm or less.

[0038] When the average crystallite size of the α crystals is within the above-mentioned preferred range, the reactivity of molybdenum trioxide powder with sulfur tends to become better.

[0039] Regarding the content ratio of MoO3 relative to the total mass of molybdenum trioxide powder, as determined by fluorescence X-ray (XRF) in this embodiment, it is preferably 99.5% by mass or more, more preferably 99.7% by mass or more, and even more preferably 99.9% by mass or more, relative to the intensity of all detected peaks.

[0040] When the MoO3 content is within the preferred range described above, high-purity molybdenum sulfide, free from concerns about impurities and exhibiting good storage stability, can be easily obtained by subjecting the molybdenum trioxide powder of this embodiment to a sulfidation reaction. Therefore, the molybdenum trioxide powder of this embodiment is suitable as a precursor for molybdenum sulfide.

[0041] The reactivity of molybdenum trioxide powder with sulfur can be evaluated as follows: 1.00 g of molybdenum trioxide powder and 1.57 g of sulfur are mixed and calcined at 400 °C for 4 hours under a nitrogen atmosphere. The conversion rate of the resulting black powder to MoS2 is then calculated and evaluated.

[0042] The conversion rate to MoS2 can be determined by using the RIR (Reference Intensity Ratio) method based on the X-ray diffraction (XRD) spectrum obtained from the black powder. The RIR value K of molybdenum sulfide (MoS2) can be used. AThe integrated intensity I of the peak near 2θ = 14.4° ± 0.5° at the (002) or (003) planes attributed to molybdenum sulfide (MoS2). A And various molybdenum oxides (MoO3 as a raw material and Mo9O as a reaction intermediate) 25 Mo4O 11 RIR values ​​K of (e.g., MoO2, etc.) B And molybdenum oxides (MoO3 as a raw material and Mo9O as a reaction intermediate) 25 Mo4O 11 The integral intensity I of the strongest peak of (MoO2, etc.) B The conversion rate R to MoS2 can be obtained from the following equation (1). C .

[0043] R C (%) = (I) A / K A ) / (Σ(I B / K B ))×100···(1)

[0044] Here, the RIR values ​​can be obtained from the ICSD database, and the analysis can be performed using integrated powder X-ray analysis software (Rigaku Corporation, PDXL Version 2).

[0045] In this embodiment of the molybdenum trioxide powder, from the viewpoint of good reactivity with sulfur, the specific surface area is preferably 10 m². 2 / g or more, preferably 20m 2 / g or more, further optimized 30m 2 / g or more. In this embodiment of the molybdenum trioxide powder, from the viewpoint of easier manufacturing, 100m³ is preferred. 2 Below / g, it can be 90m 2 Below / g, it can be 80m 2 / g or less.

[0046] In this embodiment, the crystal structure of molybdenum trioxide may further include β crystals with an average crystallite size of less than 50 nm. When the crystal structure of molybdenum trioxide includes both α and β crystals, the reactivity of the molybdenum trioxide powder with sulfur becomes more readily improved.

[0047] In this embodiment, the average crystallite size of the β crystals contained in the crystal structure of molybdenum trioxide is preferably 5 nm or more and 50 nm or less, more preferably 5 nm or more and 45 nm or less, even more preferably 10 nm or more and 40 nm or less, and particularly preferably 10 nm or more and 30 nm or less.

[0048] When the average crystallite size of the β crystals is within the above-mentioned preferred range, the reactivity of molybdenum trioxide powder with sulfur tends to become better.

[0049] In this embodiment, the α crystal structure of molybdenum trioxide can be confirmed based on the presence of the peak at the (021) plane of the α crystal of MoO3 (around 2θ: 27.32°, No. 166363 (Inorganic Crystal Structure Database (ICSD))). Furthermore, the β crystal structure can be confirmed based on the presence of the peak at the (011) plane of the β crystal of MoO3 (around 2θ: 23.01°, No. 86426 (Inorganic Crystal Structure Database (ICSD))) in the spectrum obtained by powder X-ray diffraction (XRD) using Cu-K α rays as the X-ray source.

[0050] Regarding the molybdenum trioxide powder of this embodiment, in the spectrum obtained by powder X-ray diffraction (XRD) using Cu-Kα rays as the X-ray source, the ratio of the peak intensity of the (011) plane of the β crystal belonging to MoO3 to the peak intensity of the (021) plane of the α crystal belonging to MoO3 (β(011) / α(021)) is preferably 0.1 or more, more preferably 0.2 or more, and even more preferably 0.4 or more.

[0051] In the molybdenum trioxide particles of this embodiment, the ratio (β(011) / α(021)) is preferably 10.0 or less.

[0052] For the peak intensities of the (011) plane of the β crystal belonging to MoO3 and the (021) plane of the α crystal belonging to MoO3, the maximum intensity of the peaks is read, and the above ratio (β(011) / α(021)) is calculated.

[0053] In the molybdenum trioxide powder of this embodiment, the ratio (β(011) / α(021)) is preferably 0.1 to 10.0, more preferably 0.2 to 10.0, and particularly preferably 0.4 to 10.0.

[0054] In this embodiment, the α-crystal content of the molybdenum trioxide powder is not particularly limited; it can be 20% or more, 50% or more, 70% or more, 80% or more, or 100%.

[0055] In a mixture of α and β MoO3 crystals, the content of α MoO3 crystals can be determined from the obtained spectral data using the RIR (Reference Intensity Ratio) method. The RIR value K of the α MoO3 crystal can be used. A The integrated intensity I of the (021) plane (around 2θ: 27.32°) of the α crystal of MoO3 (No. 166363 (Inorganic Crystal Structure Database, ICSD)) AAnd the RIR value K of β crystal of MoO3. B The integral intensity I of the (011) plane of the β crystal belonging to MoO3 (around 2θ: 23.01°, No. 86426 (Inorganic Crystal Structure Database, ICSD)). B The content (%) of α-crystals of MoO3 can be obtained by the following formula (2).

[0056] The content (%) of α-crystals of MoO3 = (I A / K A ) / ((I A / K A )+(I B / K B ))×100···(2)

[0057] Here, the RIR values ​​can be obtained from the ICSD database, and the analysis can be performed using integrated powder X-ray analysis software (Rigaku, PDXL Version 2).

[0058] In the molybdenum trioxide powder of this embodiment, the shape of the primary particles in the two-dimensional image taken by transmission electron microscopy (TEM) can be granular, spherical, plate-like (sheet-like), needle-like, rope-like, or ribbon-like, or a combination of these shapes. In this embodiment, the shape of the primary particles of the molybdenum trioxide powder can be ribbon-like or sheet-like with a thickness at the nanometer level. The shape of the primary particles of the 50 aforementioned molybdenum trioxide particles preferably has an average length (vertical) × width (horizontal) range of 10 to 500 nm × 10 to 500 nm, more preferably a range of 10 to 200 nm × 10 to 200 nm, and particularly preferably a range of 10 to 100 nm × 10 to 100 nm.

[0059] The β-crystal structure of molybdenum trioxide can also be determined by observing its Raman spectra at wavenumbers of 773 and 848 cm⁻¹. -1 and 905cm -1 The presence of peaks confirms the structure. The α-crystal structure of molybdenum trioxide can also be confirmed by peaks at wavenumbers of 663 and 816 cm⁻¹. -1 and 991cm -1 The presence of a peak confirms this.

[0060] The molybdenum trioxide powder of this embodiment exhibits good reactivity with sulfur, thus it is useful as a raw material for molybdenum sulfide (MoS2). Furthermore, the molybdenum trioxide powder of this embodiment can be of high purity, making it suitable for industrial applications. Additionally, the molybdenum trioxide powder of this embodiment is expected to be used in various catalyst applications.

[0061] <Method for manufacturing molybdenum trioxide powder>

[0062] The method for manufacturing molybdenum trioxide powder in this embodiment is the same as the method for manufacturing molybdenum trioxide powder in the above embodiment, including the steps of vaporizing the molybdenum oxide precursor compound to form molybdenum trioxide vapor and cooling the molybdenum trioxide vapor.

[0063] The method for manufacturing molybdenum trioxide powder according to this embodiment includes the following steps: calcining a raw material mixture containing a molybdenum oxide precursor compound and a metal compound other than the molybdenum oxide precursor compound, so that the molybdenum oxide precursor compound is vaporized to form molybdenum trioxide vapor, wherein the ratio of the metal compound to the raw material mixture is preferably 70% by mass or less when converted to oxides.

[0064] The method for manufacturing molybdenum trioxide powder in this embodiment can be used. Figure 1 The manufacturing apparatus 1 shown is suitably implemented.

[0065] Figure 1 This is a schematic diagram of an example of the apparatus used to manufacture the molybdenum trioxide powder of this embodiment. The manufacturing apparatus 1 includes: a calcining furnace 2 that calcines a molybdenum oxide precursor compound or a mixture of the aforementioned raw materials to vaporize the molybdenum oxide precursor compound; a cross-shaped cooling pipe 3 connected to the calcining furnace 2 to pulverize the molybdenum trioxide vapor vapor pulverized by the calcination; and a recovery machine 4 serving as a recovery mechanism for recovering the pulverized molybdenum trioxide powder from the cooling pipe 3. The calcining furnace 2 and the cooling pipe 3 are connected via an exhaust port 5. Furthermore, the cooling pipe 3 has an opening adjustment damper 6 at its left end at an external gas intake port (not shown) and an observation window 7 at its upper end. An exhaust device 8, serving as a first air supply mechanism, is connected to the recovery machine 4. This exhaust device 8 exhausts air, thereby drawing in the recovery machine 4 and the cooling pipe 3, and external gas is supplied to the cooling pipe 3 through the opening adjustment damper 6. That is, the exhaust device 8 performs a suction function, thereby passively generating airflow in the cooling piping 3. It should be noted that the manufacturing apparatus 1 may have an external cooling device 9, thereby allowing arbitrary control of the cooling conditions of the molybdenum trioxide vapor generated from the calcining furnace 2.

[0066] There are no particular limitations on the molybdenum oxide precursor compound, as long as it is used to form the molybdenum trioxide powder of the present invention.

[0067] As precursor compounds for the aforementioned molybdenum oxide, there are no particular limitations as long as the substance forms molybdenum trioxide vapor through calcination; examples include metallic molybdenum, molybdenum trioxide, molybdenum dioxide, molybdenum sulfide, ammonium molybdate, and phosphomolybdic acid (H3PMo). 12 O 40 ), molybdenum silicate (H4SiMo) 12 O40 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. The form of the molybdenum oxide precursor compounds is not particularly limited; for example, they can be in powder form such as molybdenum trioxide, or in liquid form such as an aqueous solution of ammonium molybdate. Powder form with good processability and energy efficiency is preferred.

[0068] As a precursor compound for molybdenum oxide, commercially available α-crystal molybdenum trioxide is preferred. Alternatively, when ammonium molybdate is used as a precursor compound for molybdenum oxide, it is converted into thermodynamically stable molybdenum trioxide through calcination, and thus the vaporized molybdenum oxide precursor compound becomes the aforementioned molybdenum trioxide.

[0069] Among these molybdenum oxide precursor compounds, from the viewpoint of easily controllable purity of molybdenum trioxide powder, average particle size of primary particles, and crystal structure, molybdenum trioxide is preferred.

[0070] Molybdenum trioxide vapor can also be formed by roasting a mixture of raw materials containing molybdenum oxide precursor compounds and metal compounds other than the aforementioned molybdenum oxide precursor compounds.

[0071] Other than the aforementioned molybdenum oxide precursor compounds, metal compounds are not particularly limited, and examples include aluminum compounds, silicon compounds, titanium compounds, magnesium compounds, sodium compounds, potassium compounds, zirconium compounds, yttrium compounds, zinc compounds, copper compounds, and iron compounds. Among these, aluminum compounds, silicon compounds, titanium compounds, and magnesium compounds are preferred.

[0072] Molybdenum oxide precursor compounds sometimes form intermediates with metal compounds other than the aforementioned molybdenum oxide precursor compounds. However, even in this case, the intermediates can be decomposed by calcination, allowing molybdenum trioxide to vaporize in a thermodynamically stable form.

[0073] Among the metal compounds other than the aforementioned molybdenum oxide precursor compounds, aluminum compounds are preferred to prevent damage to the calcination furnace. However, to improve the purity of the molybdenum trioxide powder, metal compounds other than the aforementioned molybdenum oxide precursor compounds may not be used.

[0074] Examples of aluminum compounds include aluminum chloride, aluminum sulfate, basic aluminum acetate, aluminum hydroxide, boehmite, pseudoboehmite, transitional aluminum oxides (γ-alumina, δ-alumina, θ-alumina, etc.), α-alumina, and mixed aluminum oxides with two or more crystal phases.

[0075] When calcining a raw material mixture containing a molybdenum oxide precursor compound and a metal compound other than the aforementioned molybdenum oxide precursor compound, the content of the aforementioned molybdenum oxide precursor compound relative to 100% by mass of the aforementioned raw material mixture is preferably 5% to 100% by mass, can be 10% to 100% by mass, or can be 20% to 100% by mass.

[0076] The calcination temperature varies depending on the molybdenum oxide precursor compound, metal compound, and desired molybdenum trioxide powder used, and is generally preferably set to a temperature at which the intermediate can decompose. For example, when a molybdenum compound is used as the molybdenum oxide precursor compound and an aluminum compound is used as the metal compound, aluminum molybdate can be formed as an intermediate, and the calcination temperature is preferably 500°C to 1500°C, more preferably 600°C to 1550°C, and even more preferably 700°C to 1600°C.

[0077] There are no particular restrictions on the roasting time. For example, it can be set to more than 1 minute, 1 minute to 30 hours, 10 minutes to 25 hours, or 100 minutes to 20 hours.

[0078] The heating rate also varies depending on the characteristics of the molybdenum oxide precursor compound used, the aforementioned metal compound, and the desired molybdenum trioxide powder. From the viewpoint of manufacturing efficiency, a rate of 0.1 to 100 °C / min is preferred, 1 to 50 °C / min is more preferred, and 2 to 10 °C / min is even more preferred.

[0079] There are no particular limitations on the internal pressure within the calcination furnace; it can be either positive or reduced pressure. From the viewpoint of properly discharging the molybdenum oxide precursor compound from the calcination furnace to the cooling piping, calcination is preferably carried out under reduced pressure. Specifically, the pressure reduction is preferably -5000 to -10 Pa, more preferably -2000 to -20 Pa, and even more preferably -1000 to -50 Pa. A pressure reduction of -5000 Pa or higher avoids excessive requirements for the calcination furnace's airtightness and mechanical strength, reducing manufacturing costs, and is therefore preferred. On the other hand, a pressure reduction of -10 Pa or lower prevents blockage of the molybdenum oxide precursor compound at the furnace's discharge port, and is therefore preferred.

[0080] It should be noted that when gas is supplied to the roasting furnace during roasting, the temperature of the supplied gas is preferably 5 to 500°C, and more preferably 10 to 100°C.

[0081] In addition, the gas delivery speed is preferably 1 to 500 L / min, more preferably 10 to 200 L / min, relative to the effective volume of the roasting furnace of 100 L.

[0082] The temperature of the vaporized molybdenum trioxide vapor varies depending on the type of molybdenum oxide precursor compound used, preferably 200–2000°C, and more preferably 400–1500°C. It should be noted that if the temperature of the vaporized molybdenum trioxide vapor is below 2000°C, it tends to easily pulverize in the cooling piping through the supply of external air (0–100°C).

[0083] The discharge rate of molybdenum trioxide vapor from the calcining furnace can be controlled based on the amount of the aforementioned molybdenum oxide precursor compound, the amount of the aforementioned metal compound, the temperature of the calcining furnace, the gas supply to the calcining furnace, and the diameter of the calcining furnace exhaust port. It also varies depending on the cooling capacity of the cooling piping; the discharge rate of molybdenum trioxide vapor from the calcining furnace to the cooling piping is preferably 0.001–100 g / min, more preferably 0.1–50 g / min.

[0084] In addition, the content of molybdenum trioxide vapor in the gas discharged from the roasting furnace is preferably 0.01 to 1000 mg / L, more preferably 1 to 500 mg / L.

[0085] Then, the above molybdenum trioxide vapor is cooled and pulverized.

[0086] Cooling of molybdenum trioxide vapor is achieved by keeping the cooling pipes at a low temperature. Examples of cooling mechanisms include, as described above, cooling based on airflow into the cooling pipes, cooling utilizing the cooling mechanism inherent in the cooling pipes, and cooling utilizing an external cooling device.

[0087] There are no particular limitations on the cooling temperature (temperature of the cooling piping), but it is preferred to be -100 to 600°C, and more preferably -50 to 400°C.

[0088] There is no particular limitation on the cooling rate of molybdenum trioxide vapor, but it is preferably 100 to 100,000 °C / s, and more preferably 1,000 to 50,000 °C / s. It should be noted that the faster the cooling rate of molybdenum trioxide vapor, the more likely it is to obtain molybdenum trioxide powder with small particle size and large specific surface area.

[0089] When the cooling method is based on the supply of gas to the cooling piping, the temperature of the supplied gas is preferably -100 to 300°C, more preferably -50 to 100°C.

[0090] In addition, the preferred gas delivery velocity is 0.1–20 m / s. 3 / minute, more preferably 1-10m 3 / minute. The gas delivery velocity is 0.1m. 3 A cooling rate of 20 m / min or higher can achieve high cooling speed and prevent blockage of cooling pipes, making it the preferred option. On the other hand, the gas delivery velocity is 20 m / s. 3 When the speed is below a certain level, there is no need for an expensive first air supply mechanism (exhaust fan, etc.), which can reduce manufacturing costs, so it is preferred.

[0091] The powder obtained by cooling molybdenum trioxide vapor is conveyed to a recycling machine for recovery.

[0092] In the method for manufacturing molybdenum trioxide powder according to this embodiment, the powder obtained by cooling the above-mentioned molybdenum trioxide vapor can be calcined again at a temperature of 100°C to 500°C.

[0093] That is, the molybdenum trioxide powder obtained by the method for manufacturing molybdenum trioxide powder according to this embodiment can be calcined again at a temperature of 100°C to 500°C. The calcination temperature for the second calcination can be 120°C to 450°C, or 140°C to 400°C, and the calcination time for the second calcination can be set, for example, 1 minute to 4 hours, 10 minutes to 5 hours, or 100 minutes to 6 hours. It should be noted that by calcining again, a portion of the β crystal structure of molybdenum trioxide disappears. If calcined at a temperature above 350°C for 4 hours, the β crystal structure in the molybdenum trioxide powder disappears, and the ratio (β(011) / α(021)) becomes 0, resulting in molybdenum trioxide with a crystal structure entirely composed of α crystals (100%).

[0094] Furthermore, when the molybdenum trioxide powder obtained by the manufacturing method of molybdenum trioxide powder in this embodiment is placed at an atmosphere temperature of 5°C to 200°C and a humidity of 50% to 95% for 1 day to 2 weeks, the β crystal structure in the molybdenum trioxide powder will also disappear, and the above ratio (β(011) / α(021)) becomes 0, resulting in molybdenum trioxide with a crystal structure of α crystals (100%).

[0095] When the molybdenum trioxide powder obtained by the method for manufacturing molybdenum trioxide powder according to this embodiment is placed to achieve a molybdenum trioxide with a crystal structure of 100% α crystals, the atmosphere temperature can be 5°C to 200°C, or 15°C to 100°C. The humidity can be 50% to 95%, or 70% to 95%. The placement time can be 1 day to 2 weeks, or 1 day to 1 week.

[0096] According to the method for manufacturing molybdenum trioxide powder of this embodiment, molybdenum trioxide powder that is entirely composed of α crystals (100%) can be obtained.

[0097] Example

[0098] The present invention will be further described in detail below by way of examples, but the present invention is not limited to these examples.

[0099] [Method for determining the average particle size of primary particles of molybdenum trioxide powder]

[0100] 0.1 g of molybdenum trioxide powder was added to 10 cc of ethanol, and the mixture was ultrasonically treated in an ice bath for 4 hours. The concentration was then adjusted with ethanol to a suitable range that could be measured using a dynamic light scattering particle size distribution analyzer (MicrotracBEL Nanotrac Wave II). The resulting sample was then used to measure the particle size distribution in the range of 0.0001–10 μm using the dynamic light scattering particle size distribution analyzer (MicrotracBEL Nanotrac Wave II), and the median particle size D was calculated. 50 Among them, for the median particle size D 50 For particles larger than 10 μm, solutions were prepared similarly, and the particle size distribution in the range of 0.015–500 μm was measured using a laser diffraction particle size distribution measuring device (Shimadzu SALD-7000). The median particle size D was then calculated. 50 .

[0101] In addition, molybdenum trioxide particles constituting the molybdenum trioxide powder were dispersed in ethanol. The shape of individual particles or the smallest units constituting aggregates was confirmed in two-dimensional images obtained by transmission electron microscopy (TEM, JEOL JEM1400). The major axis (Ferret diameter of the longest observed portion) and minor axis (the shorter Ferret diameter in the direction perpendicular to the Ferret diameter of the longest portion) were measured, and their average value was obtained as the primary particle size. The same operation was performed on 50 randomly selected primary particles, and the average primary particle size was calculated from the average of the primary particle sizes. In particular, for particles larger than 1 micrometer, scanning electron microscopy (SEM) was also used to obtain the average primary particle size as a reference value.

[0102] Crystal structure analysis of molybdenum trioxide powder: XRD method

[0103] The molybdenum compound samples obtained in each example were filled into a sample holder with a depth of 0.5 mm and placed in a wide-angle X-ray diffraction (XRD) apparatus (Ultima IV manufactured by Rigaku Co., Ltd., optical system using incident-side parallel beam method + scintillation counting detector, rotating platform) for measurement under the conditions of Cu / Kα rays, 40 kV / 40 mA, scanning speed of 0.3° / min, step of 0.02°, and scanning range of 10° or more and 70° or less.

[0104] [Method for determining the crystallite size of molybdenum trioxide powder]

[0105] The XRD instrument constants were determined using Rigaku Co., Ltd.'s XRD spectral analysis software (PDXL Version 2) with LaB6 (NISTSRM660c LaB6 Standard Powder) as the standard material, and the crystallite size was evaluated using the Scherrer method (with Scherrer constant K = 0.94).

[0106] [Shape of molybdenum trioxide particles]

[0107] The molybdenum trioxide particles that make up the molybdenum trioxide powder were dispersed in ethanol, and the shape of individual particles or the smallest unit constituting the aggregate was confirmed in the two-dimensional image of the transmission electron microscope (TEM, JEOL JEM1400).

[0108] [Purity determination of molybdenum trioxide: XRF analysis]

[0109] Using a Primus IV fluorescence X-ray analysis apparatus (manufactured by RIGAKU Co., Ltd.), approximately 70 mg of the recovered molybdenum trioxide powder sample was placed on filter paper, covered with a PP film, and subjected to compositional analysis. The molybdenum content obtained from the XRF analysis results was calculated by converting molybdenum trioxide to 100% by mass of the molybdenum trioxide powder (mass %).

[0110] [Specific Surface Area Determination of Molybdenum Trioxide Powder: BET Method]

[0111] For samples containing molybdenum trioxide or molybdenum sulfide powder, the surface area was measured using a specific surface area meter (MicrotracBEL, BELSORP-mini). The average surface area per 1g of sample was calculated from the nitrogen adsorption amount based on the BET method, and this was taken as the specific surface area (m²). 2 / g).

[0112] [Conversion rate of molybdenum trioxide powder to MoS2]

[0113] 1.00 g of molybdenum trioxide powder and 1.57 g of sulfur were mixed and calcined at 400 °C for 4 hours under a nitrogen atmosphere. The resulting black powder was then analyzed by X-ray diffraction (XRD). The RIR value K of molybdenum sulfide (MoS2) was then determined using the RIR (reference intensity ratio) method. A The integrated intensity I of the peak near 2θ = 14.4° ± 0.5° at the (002) or (003) planes attributed to molybdenum sulfide (MoS2). A And various molybdenum oxides (MoO3 as a raw material and Mo9O as a reaction intermediate) 25 Mo4O 11 RIR values ​​K of (e.g., MoO2, etc.) BAnd molybdenum oxides (MoO3 as a raw material and Mo9O as a reaction intermediate) 25 Mo4O 11 The integral intensity I of the strongest peak of (MoO2, etc.) B The conversion rate R to MoS2 can be obtained from the following equation (1). C .

[0114] R C (%) = (I) A / K A ) / (Σ(I B / K B ))×100···(1)

[0115] Here, the RIR values ​​were used from the ICSD database, and the analysis was performed using the integrated powder X-ray analysis software (Rigaku PDXL Version 2).

[0116] The conversion rate to MoS2 was evaluated according to the following benchmarks.

[0117] A: Conversion rate over 95%

[0118] B: Conversion rate less than 95%

[0119] [Example 1]

[0120] The calcining furnace was equipped with an RHK simulation device (manufactured by NORITAKE CO., LIMITED), and the dust collector was a VF-5N dust collector (manufactured by AMANO Corporation) for the production of molybdenum trioxide.

[0121] 1.5 kg of aluminum hydroxide (manufactured by Nippon Light Metals Co., Ltd.) and 1 kg of molybdenum trioxide (manufactured by Nippon Inorganic Co., Ltd.) were mixed and then placed in a sagger and calcined at 1100°C for 10 hours. During calcination, external gas (air flow rate: 150 L / min, external gas temperature: 25°C) was introduced from the side and bottom of the calcining furnace. After the molybdenum trioxide evaporated in the furnace, it cooled near the dust collector and precipitated in particulate form, so the molybdenum trioxide was recovered using the dust collector (1).

[0122] After calcination, 1.0 kg of alumina as blue powder and 0.8 kg of molybdenum trioxide (1) recovered from the dust collector were removed from the sagger. The median particle size D of the primary particles of the recovered molybdenum trioxide (1) was determined by dynamic light scattering. 50 The particle size was 87.8 nm, and the particle shape observed by TEM was either ribbon-like or granular. Fluorescence X-ray diffraction confirmed the purity (MoO3 content) of molybdenum trioxide (1) to be 99.9% by mass.

[0123] Furthermore, for molybdenum trioxide (1), crystal structure analysis based on X-ray diffraction (XRD) was performed. The results showed peaks belonging to α-crystal and β-crystal molybdenum trioxide, but no other peaks were observed. Next, the peak intensity ratio of the (011) plane of the β-crystal and the (021) plane of the α-crystal were compared, and the result showed that β(011) / α(021) was 4. Furthermore, the XRD spectral analysis software PDXL Version 2 manufactured by Rigaku Co., Ltd. was used, and the XRD device constant was determined using LaB6 (NIST SRM660c LaB6 Standard Powder) as the standard material. The Scherrer method was used to evaluate the crystallite size, and the results confirmed that molybdenum trioxide (1) has a crystal structure containing α-crystal with an average crystallite size of 15.7 nm and β-crystal with an average crystallite size of 16.8 nm.

[0124] The content of MoO3 α crystals in the mixture of MoO3 α and β crystals was determined using the RIR (Reference Intensity Ratio) method based on the obtained spectral data. The RIR value K of MoO3 α crystals was used. A The integrated intensity I of the (021) plane (around 2θ: 27.32°) of the α crystal of MoO3 (No. 166363 (Inorganic Crystal Structure Database, ICSD)) A And the RIR value K of β crystal of MoO3. B The integral intensity I of the (011) plane of the β crystal belonging to MoO3 (around 2θ: 23.01°, No. 86426 (Inorganic Crystal Structure Database, ICSD)). B The content (%) of α-crystals of MoO3 can be obtained by the following formula (2).

[0125] The content (%) of α-crystals of MoO3 = (I A / K A ) / ((I A / K A )+(I B / K B ))×100···(2)

[0126] Here, the RIR values ​​can be obtained from the ICSD database, and the analysis can be performed using integrated powder X-ray analysis software (Rigaku, PDXL Version 2). The content of α-crystals in MoO3, as determined by equation (2), is 30%.

[0127] 1.00 g (6.94 mmol) of molybdenum trioxide (1) and 1.56 g (48.6 mmol) of sulfur (Kanto Chemical, powder) were mixed and calcined at 400 °C for 4 hours under a nitrogen atmosphere in a high-temperature tubular furnace (Yamada Electric Co., Ltd., TSS type) to obtain 1.12 g of black powder. Structural analysis of this black powder showed a conversion rate of 99.9% to MoS2, confirming a rapid reaction with sulfur.

[0128] [Example 2]

[0129] Molybdenum trioxide calcined using the same method as in Example 1 above was stored at 95% humidity and 50°C for 5 days. The particles grew into ribbons or needles (1–2 μm in length), and 100% α-crystals of molybdenum trioxide (2) could be recovered. The average crystallite size of the α-crystals was 20.4 nm. Fluorescence X-ray diffraction confirmed the purity (MoO3 content) of molybdenum trioxide (2) to be 99.9% by mass.

[0130] In addition, molybdenum trioxide (2) was used instead of molybdenum trioxide (1), and molybdenum sulfide was obtained in the same manner as in Example 1. The structure of the obtained black powder was analyzed by XRD, and the conversion rate to MoS2 was 99.9%, confirming that the reaction with sulfur occurred rapidly.

[0131] [Example 3]

[0132] Molybdenum trioxide calcined using the same method as in Example 1 above was heated at 355°C for 3 hours, resulting in the growth of ribbons or large particles. This allowed for the recovery of molybdenum trioxide (3) that was entirely composed of α-crystals (100%). The average crystallite size of this α-crystal was 27.6 nm.

[0133] In addition, molybdenum trioxide (3) was used instead of molybdenum trioxide (1), and molybdenum sulfide was obtained in the same manner as in Example 1. The structure of the obtained black powder was analyzed by XRD, and the conversion to MoS2 was 99.9%, confirming that the reaction with sulfur occurred rapidly.

[0134] [Comparative Example 1]

[0135] 1.00 g (6.94 mmol) of commercially available small-sized molybdenum trioxide (1') (manufactured by Nippon Inorganic Chemicals Co., Ltd., Lot No. 00501-C) and 1.56 g (48.6 mmol) of sulfur (manufactured by Kanto Chemicals, powder) were mixed and calcined at 400 °C for 4 hours under a nitrogen atmosphere in a high-temperature tubular furnace (manufactured by Yamada Electric Co., Ltd., TSS type) to obtain 1.13 g of black powder. XRD analysis of the black powder revealed it to be a mixture of MoS2, MoO2, and MoO3, confirming low reactivity with sulfur.

[0136] Furthermore, for molybdenum trioxide (1'), the same XRD-based crystal structure analysis was performed as in Example 1, and the results showed that all molybdenum trioxide (1') had an α-crystal structure. Additionally, the crystallite size was evaluated as in Example 1, and the average crystallite size of the α-crystals of molybdenum trioxide (1') was 57.0 nm. Fluorescence X-ray diffraction confirmed that the purity (MoO3 content) of molybdenum trioxide (1') was 99.9% by mass.

[0137] For each molybdenum oxide powder obtained in Examples 1-3 and Comparative Example 1, the content (%) of α crystals, the average crystallite size (nm) of α crystals, the average crystallite size (nm) of β crystals, and the average particle size D were compared. 50 (nm), average particle size based on TEM (nm), average particle size based on SEM (nm), shape, BET specific surface area (m²) 2 The evaluation results of the molybdenum trioxide powder (MoO3 content ratio (mass%)) and conversion rate to MoS2 are shown in Table 1. Additionally, the results of the determination of the crystallite size of each molybdenum trioxide powder are shown in Table 2.

[0138] Figure 2A The image shows the XRD pattern of Example 1, the position diagram of the α crystal peak in the top row, and the position diagram of the β crystal peak in the bottom row (middle). Figure 2B The XRD pattern of Comparative Example 1 and the position diagram of the α crystal peaks in the top row are shown.

[0139] Figure 3A This is an analysis diagram of the crystallite size and diffraction intensity of Example 1. Figure 3B The diagram shows the analysis of crystallite size and diffraction intensity for Comparative Example 1.

[0140] [Table 1]

[0141]

[0142] [Table 2]

[0143]

[0144] The preferred embodiments of the present invention have been described above, but the present invention is not limited to these embodiments. Features may be added, omitted, substituted, and other modifications may be made without departing from the spirit of the present invention. The present invention is not limited by the foregoing description, but only by the scope of the appended claims.

[0145] Explanation of reference numerals in the attached figures

[0146] 1 Manufacturing apparatus

[0147] 2. Firing oven

[0148] 3 Cooling piping

[0149] 4. Recycling machine

[0150] 5. Exhaust port

[0151] 6. Adjustable damper opening

[0152] 7 Observation Window

[0153] 8. Exhaust system

[0154] 9. External cooling device

Claims

1. A molybdenum trioxide powder comprising an aggregate of primary particles with a crystal structure containing molybdenum trioxide, said crystal structure comprising α crystals with an average crystallite size of less than 50 nm, wherein the median particle size D of said primary particles is determined by dynamic light scattering. 50 The α crystal content is above 20% and is below 2000nm.

2. The molybdenum trioxide powder according to claim 1, wherein, The content of MoO3, as determined by fluorescence X-ray diffraction, is 99.5% by mass or more relative to the total weight of the molybdenum trioxide powder.

3. The molybdenum trioxide powder according to claim 1, wherein the specific surface area determined by the BET method is 10 m². 2 / g or more.

4. The molybdenum trioxide powder according to claim 1, wherein, The crystal structure also includes β crystals with an average crystallite size of less than 50 nm.

5. The molybdenum trioxide powder according to claim 4, wherein, In the powder X-ray diffraction spectrum obtained using Cu-Kα rays as the X-ray source, the ratio of the peak intensity of the (011) plane of the β crystal belonging to MoO3 to the peak intensity of the (021) plane of the α crystal belonging to MoO3, β(011) / α(021), is greater than 0.

1.

6. The molybdenum trioxide powder according to claim 5, wherein, In the spectrum obtained by powder X-ray diffraction using Cu-Kα rays as the X-ray source, the ratio of the peak intensity of the (011) plane of the β crystal belonging to MoO3 to the peak intensity of the (021) plane of the α crystal belonging to MoO3, β(011) / α(021), is less than 10.

0.

7. The molybdenum trioxide powder according to claim 1, wherein, The primary particles are in the shape of strips or sheets.

8. A method for manufacturing molybdenum trioxide powder according to any one of claims 1 to 7, comprising the following steps: vaporizing a molybdenum oxide precursor compound to form molybdenum trioxide vapor, and cooling the molybdenum trioxide vapor.

9. The method for manufacturing molybdenum trioxide powder according to claim 8, comprising the following steps: calcining a raw material mixture containing a molybdenum oxide precursor compound and a metal compound other than the molybdenum oxide precursor compound to vaporize the molybdenum oxide precursor compound to form molybdenum trioxide vapor, wherein the ratio of the metal compound to the raw material mixture is 95% by mass or less in oxide conversion.

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