Method for producing zirconium tungstate

Abstract

Provided is a method for producing zirconium tungstate, comprising: a reaction step for obtaining a precursor by heating and reacting a raw material containing zirconium and tungsten in a pressure-resistant container under the action of pressure; and a heat treatment step in which the precursor is heated to obtain a product containing ZrW2O8, and in the reaction step, the raw materials are reacted in a state in which sulfate ions are present in the pressure vessel.

Description

Technical Field

[0001] This specification discloses a method for manufacturing zirconium tungstate. Background Art

[0002] Compared with ordinary substances that expand when heated, zirconium tungstate (ZrW2O8) is one of the substances showing negative thermal expansion that contracts upon heating. Such negative thermal expansion materials are expected to be used, for example, as packaging materials for semiconductor chips mounted on electronic components by mixing them as fillers with positive thermal expansion materials such as resins to form composite materials with suppressed thermal expansion.

[0003] Depending on the application, for example, zirconium tungstate in the form of fine powder on the order of sub-microns is required. Methods for manufacturing such fine zirconium tungstate include the hydrothermal method.

[0004] For example, Patent Document 1 lists: "A method of synthesizing a precursor by hydrothermal synthesis by heating a mixture of an aqueous tungstate solution, an aqueous zirconium compound solution having a Zr=O structure, and concentrated hydrochloric acid, and performing heat treatment on it at a temperature of around 600°C." Based on this, attention is focused on the following problem: "The hydrothermal synthesis method has the advantage of being able to synthesize small particles of less than 1 micron, but the synthesis of the precursor requires synthesis conditions of 130°C or higher in a hydrochloric acid acidic solution, so a pressure-resistant autoclave with an acid-resistant fluororesin inner cylinder is used. In addition, if the reaction is not carried out for a long time (for example, if the reaction temperature is 150°C, it is more than 6 hours), the precursor yield is less than 50%. Therefore, mass production is difficult, and there is a problem of manufacturing cost." To solve this problem, Patent Document 1 proposes "A method for manufacturing ZrW2O8 particles, wherein a mixture of an aqueous tungstate solution, an aqueous zirconium compound solution having a Zr=O structure, and concentrated hydrochloric acid is heated in a reaction vessel while setting a temperature difference between the liquid phase and the gas phase in the reaction vessel to generate ZrW2O8 precursor particles, and then the ZrW2O8 precursor particles are heat-treated to manufacture ZrW2O8 particles."

[0005] Prior Art Documents

[0006] Patent Documents

[0007] Patent Document 1: Japanese Unexamined Patent Application Publication No. 2016-179915 Summary of the Invention

[0008] Problems to be Solved by the Invention

[0009] In syntheses such as the hydrothermal method, as described in Patent Document 1, a hydrochloric acid system is mostly used. However, when using a hydrochloric acid system, when synthesizing a precursor such as ZrW2O7(OH)2(H2O)2 from raw materials containing zirconium and tungsten, the crystal grows in a needle shape, and the resulting precursor becomes needle-shaped. When such a needle-shaped precursor is heated to produce zirconium tungstate, there is a tendency for the zirconium tungstate to also become needle-shaped. In needle-shaped zirconium tungstate, when mixed as a filler in a resin or the like, the viscosity may increase and the fluidity (thixotropy) may deteriorate.

[0010] In this specification, a method for producing zirconium tungstate is provided, which can suppress needle-shaped products and obtain granular products.

[0011] Solution to the problem

[0012] The method for producing zirconium tungstate disclosed in this specification is as follows. It includes a reaction step of heating raw materials containing zirconium and tungsten under pressure in a pressure-resistant container to make them react to obtain a precursor, and a heat treatment step of heating the precursor to obtain a product containing ZrW2O8. In the reaction step, the raw materials are made to react in a state where sulfate ions are present in the pressure-resistant container.

[0013] Advantageous effects of the invention

[0014] According to the above method for producing zirconium tungstate, needle-shaped products can be suppressed and granular products can be obtained. Description of the drawings

[0015] Figure 1 It is a flowchart showing an example of the case where the solvothermal method is used in the reaction step in the method for producing zirconium tungstate in one embodiment.

[0016] Figure 2 It is a flowchart showing an example of the case where the hydrothermal method or the dry gel conversion (DGC) method is used in the reaction step in the method for producing zirconium tungstate in another embodiment.

[0017] Figure 3 It is an X-ray diffraction pattern of the product obtained in Example 1.

[0018] Figure 4 It is an SEM image of the product obtained in Example 1.

[0019] Figure 5 It is an X-ray diffraction pattern of the product obtained in Example 2.

[0020] Figure 6 It is an SEM image of the product obtained in Example 2.

[0021] Figure 7It is the X-ray diffraction pattern of the product obtained in Example 3.

[0022] Figure 8 It is the SEM image of the product obtained in Example 3.

[0023] Figure 9 It is the X-ray diffraction pattern of each product obtained in Example 4.

[0024] Figure 10 It is the SEM image of the product obtained in Example 4 under the condition of sulfuric acid concentration of 1.0 M.

[0025] Figure 11 It is the SEM image of the product obtained in Example 4 under the condition of sulfuric acid concentration of 0.5 M.

[0026] Figure 12 It is the SEM image of the product obtained in Example 4 under the condition of sulfuric acid concentration of 0.25 M. Detailed implementation mode

[0027] Hereinafter, the implementation modes of the above-mentioned method for manufacturing zirconium tungstate will be described in detail.

[0028] In a method for manufacturing zirconium tungstate according to an embodiment, it includes: a reaction step of synthesizing a precursor (such as ZrW2O7(OH)2(H2O)2, etc.) from raw materials containing zirconium and tungsten; and a heat treatment step of heating the precursor to obtain a product containing ZrW2O8.

[0029] In the reaction step, for example, a solvothermal method, a hydrothermal method, or a dry gel conversion (DGC: Dry Gel Conversion) method, etc. can be used. In such a synthesis method, the above-mentioned raw materials are heated under pressure in a pressure-resistant container (autoclave) to make them react. In the case of the solvothermal method or the hydrothermal method, when pressurizing and heating, the raw materials are stirred in the liquid phase of an organic solvent or water as the solvent. In the case of the DGC method, the pressurization and heating of the raw materials are carried out in the gas phase containing the vapor of the solvent.

[0030] Regardless of which method is used, such as the solvothermal method, the hydrothermal method, or the DGC method, in this embodiment, in the reaction step, sulfate ions are present in the pressure-resistant container, and the raw materials react in the presence of the sulfate ions. Thus, the formation of needle-like precursors can be inhibited, and granular precursors can be obtained. It is considered that the reason why the precursor becomes a granular crystal due to sulfate ions is that the sulfate ions in the pressure-resistant container act in a manner that does not hinder nucleation but inhibits crystal growth. It is considered that in most cases, when crystallization occurs in the form of a hydroxide after nucleation, due to the characteristics of the crystal structure (tetragonal), the crystal grows longitudinally. In contrast, in this embodiment, the sulfate ions function as an inhibitor of its growth. However, it is not limited to such a theory. It should be noted that the case where needle-like or rod-like products are formed when hydrochloric acid systems or chlorides are used in the hydrothermal method is shown in "Hydro thermal synthesis of ZrW2O8 nanorods" (X. Xing et al., January 2006, Physica B 371, p. 81 - 84).

[0031] (Raw materials)

[0032] As raw materials, zirconium compounds and tungsten compounds can be used. As zirconium compounds, zirconium sulfate (Zr(SO4)2) etc. can be cited. As tungsten compounds, sodium tungstate (Na2WO4), ammonium paratungstate ((NH4) 10 W 12 O 41 ) etc. can be cited. Such compounds can also be hydrates.

[0033] The zirconium compound and / or tungsten compound of the raw materials preferably contain sulfuric acid in the form of sulfates etc. Thus, the heating and pressurization of the raw materials in the reaction step can be easily carried out in the state where sulfate ions are present. From this viewpoint, the raw materials preferably contain zirconium sulfate and its hydrate as zirconium compounds. However, as long as sulfate ions can be present in the pressure-resistant container of the reaction step, the raw materials do not necessarily contain sulfuric acid. Instead of the raw materials containing sulfuric acid or in addition to the raw materials containing sulfuric acid, as described later, sulfuric acid can be added to the pressure-resistant container and / or sulfuric acid can be impregnated into the raw material gel etc.

[0034] Regarding the ratio of the zirconium compound to the tungsten compound in the raw materials, the ratio of the atomic percentage (atm%) of tungsten in the tungsten compound to the atomic percentage (atm%) of zirconium in the zirconium compound (W / Zr) can be set to 1.0 - 3.0.

[0035] In the solvothermal method, as Figure 1As shown, raw materials containing zirconium compounds and tungsten compounds can be introduced into a pressure-resistant container for a reaction process. The reason is considered to be that in the solvothermal method, the zirconium compounds and tungsten compounds introduced into the pressure-resistant container dissolve in the solvent under the high temperature / high pressure of the reaction process, etc., and are uniformly mixed in the solvent, and a synthesis reaction occurs in this state. On the other hand, in the DGC method and the hydrothermal method, as Figure 2 shown, a gel preparation process can be performed on the zirconium compound and the tungsten compound as described below, and the resulting raw material gel is used as a raw material in the reaction process. In the DGC method and the hydrothermal method, for example, if an aqueous solution of zirconium sulfate as a zirconium compound of the raw material is mixed with an aqueous solution of sodium tungstate as a tungsten compound, precipitation or coprecipitation immediately occurs to form a gel state. After such a gel preparation process, the resulting raw material gel can be supplied to the reaction process. In any method or process, the reaction is carried out in the presence of sulfate ions, thereby suppressing the formation of needle-shaped crystals.

[0036] (Gel preparation process)

[0037] In the case of using the hydrothermal method or the DGC method, in the gel preparation process, raw materials containing zirconium compounds and tungsten compounds are mixed in a liquid such as water to prepare a raw material gel.

[0038] Specifically, for example, sometimes a zirconium compound such as zirconium sulfate is added to pure water to make an aqueous solution of zirconium sulfate, etc., and a tungsten compound such as tungstate is added to pure water to make an aqueous solution of tungstate, etc., and then they are mixed and stirred. The stirring speed at this time is not particularly limited as long as the two aqueous solutions can be uniformly mixed. In addition, the liquid temperature can be set to room temperature or normal temperature as long as it is not an extremely high or low temperature at which the pH changes. The conditions can be appropriately changed.

[0039] Thereby, a gel-like coprecipitate can be formed. Then, filtration such as suction filtration or vacuum filtration and other solid-liquid separations are carried out, and after washing with pure water as needed, drying is carried out, for example, in a vacuum atmosphere to obtain a raw material gel. In the raw material gel, zirconium compounds such as zirconium sulfate and tungstate compounds such as tungstate can be included in a dispersed state.

[0040] (Reaction process)

[0041] In the reaction process, a precursor is synthesized from the zirconium compound and the tungsten compound in the raw material or the raw material gel by the solvothermal method, the hydrothermal method or the DGC method, etc.

[0042] The solvothermal method; the hydrothermal method and the DGC method are methods in which the dissolution and precipitation of raw materials occur in a liquid phase or a gas phase containing a solvent, and can perform synthesis stably and easily compared with solid-phase reactions. In addition, there are advantages such as high crystallinity and compositional uniformity of the reaction product.

[0043] In the solvothermal method, a raw material containing a zirconium compound and a tungsten compound and an organic solvent are charged into a pressure-resistant container, and while stirring in the liquid phase of the organic solvent, the raw material is heated under pressure (for example, the autogenous pressure described below or a pressure higher than that) to cause a reaction. As the organic solvent, an organic solvent containing a diol such as 1,4-butanediol can be used. In particular, when using an organic solvent containing 1,4-butanediol, it is presumed that tetrahydrofuran (THF) and water are obtained under high temperature and high pressure through the dehydration reaction of 1,4-butanediol based on sulfuric acid. In this case, it is considered that the dehydration reaction of 1,4-butanediol under high temperature and high pressure and the dissolution of the raw material into the organic solvent occur simultaneously or successively, promoting the reaction. Therefore, the organic solvent preferably contains 1,4-butanediol. For example, if a stirrer such as a magnetic stirrer is used for stirring the liquid phase during the reaction, the stirring speed is sometimes set to 600 rpm or more for sufficient stirring. Or, when using a relatively large stirring blade or paddle, the stirring speed is sometimes set to less than 600 rpm. The stirring speed may affect the control of the particle shape.

[0044] Regarding the hydrothermal method, the raw material is set as the above-mentioned raw material gel, and pure water or the like is used as the solvent instead of the organic solvent in the solvothermal method. Other than that, it can be carried out substantially in the same manner as the solvothermal method.

[0045] In the DGC method, the dried raw material gel is arranged in a pressure-resistant container containing a liquid solvent in a manner not in contact with the liquid. Then, in this pressure-resistant container, the solvent is evaporated, and in the gas phase containing the vapor of the solvent, the raw material is reacted by pressurization (for example, the autogenous pressure described below or a pressure higher than that) and heating. As the solvent, water or a solution obtained by adding sulfuric acid to water can be used.

[0046] In the reaction step, it is preferable to set the temperature inside the pressure-resistant container to 100°C to 300°C, maintain this state for 30 minutes or more, further maintain it for 1 hour or more, and further maintain it for 5 hours or more. By raising the temperature to a certain extent, there is a tendency that crystals are formed in a shorter time, and in addition, the product becomes non-needle-shaped granular, such as more ideal shapes like square, spherical, and cubic shapes. The temperature can also be set considering the material of the pressure-resistant container, such as made of polytetrafluoroethylene or SUS. If there is an appropriate liquid volume inside the pressure-resistant container, then inside the pressure-resistant container, due to heating, the solvent evaporates and the pressure inside the pressure-resistant container increases. In the reaction step, there is no need to intentionally control the pressure inside the pressure-resistant container, and it can be made to react under the action of the pressure based on the vapor pressure (the self-generated pressure shown by the solvent) when heated to a specified temperature, but other gases such as nitrogen can also be supplied to increase the pressure. The pressure inside the pressure-resistant container during the reaction can be set to be above the self-generated pressure, and as an example, it can be set to 2 MPa. If the pressure is too high, solvent decomposition etc. may occur. In addition, depending on the specifications of the pressure-resistant container and other conditions, sometimes the pressure inside the pressure-resistant container is set to 30 MPa or less, and further set to 20 MPa or less. The time for maintaining the above temperature can be appropriately set considering economy, mass productivity, etc., and sometimes it is set to 24 hours or less. By performing the reaction step in this way, the raw materials are dissolved in the liquid phase or gas phase and the reaction product is obtained.

[0047] The precursor obtained in the reaction step often contains ZrW2O7(OH)2(H2O)2, but in the DGC method etc., sometimes such hydroxides are not formed. In this case, the precursor sometimes does not crystallize and becomes an amorphous state.

[0048] In the reaction step as described above, when the raw materials or the raw material gel are made to react inside the pressure-resistant container, it is set to a state where sulfate ions are present inside the pressure-resistant container. Thereby, there is a tendency to suppress the formation of needle-shaped precursors and it is easy to obtain granular precursors.

[0049] For example, in the solvothermal method, when the raw materials contain sulfates, sometimes sulfate ions derived from the sulfates are present inside the pressure-resistant container in the reaction step.

[0050] In the hydrothermal method, in order to have sulfate ions present inside the pressure-resistant container in the reaction step after the gel preparation step, if necessary, sulfuric acid can be introduced into the pressure-resistant container in the form of a sulfuric acid aqueous solution etc. when performing the reaction step. In addition, in the DGC method, the raw material gel can also be impregnated in a sulfuric acid aqueous solution etc. before the reaction step to impregnate the raw material gel with sulfuric acid. In this case, the raw material gel contains sulfuric acid, and by supplying it to the reaction step, sulfate ions are generated inside the pressure-resistant container.

[0051] Particularly in the DGC method, during the reaction, sulfate ions are preferably present in the pressure-resistant container at 8.2% by mass to 49.2% by mass. Thereby, it is easy to obtain fine precursors. If the amount of sulfate ions is too small, sufficient micronization may not be achieved. The amount of sulfate ions in the pressure-resistant container is sometimes preferably set to 32.8% by mass or less and, in addition, 16.4% by mass or more. It should be noted that in the solvothermal method, if the amount of sulfate ions is too large, the yield may decrease, and if the amount of sulfate ions is too small, the formation of needle-like precursors may not be sufficiently suppressed. In the hydrothermal method, there is a tendency that the more sulfate ions there are, the finer the micronization. The amount of sulfate ions in the pressure-resistant container is sometimes preferably set to 32.8% by mass or less and, in addition, 16.4% by mass or more.

[0052] After the reaction, the precursor obtained by solid-liquid separation based on suction filtration or the like can be dried, for example, in a vacuum atmosphere.

[0053] (Heat treatment process)

[0054] The precursor generated in the reaction process becomes a product such as an oxide containing ZrW2O8 by heating in the heat treatment process.

[0055] The conditions of the heat treatment process can be appropriately changed. For example, sometimes in air or an inert atmosphere such as argon, the precursor is heated to 600 °C to 700 °C for 0.5 hours to 3 hours. In the case of too low a temperature or too short a time, crystallization may not occur. On the other hand, in the case of too high a temperature or too short a time, the temporarily crystallized ZrW2O8 may decompose into ZrO2 and WO3.

[0056] Regarding the zirconium tungstate thus manufactured, since the formation of needle-like precursors in the reaction process is suppressed, it is mostly granular rather than needle-like. When the granular zirconium tungstate is mixed with a resin or the like as a filler, it can suppress an increase in viscosity and exhibit the required fluidity (thixotropy).

[0057] It should be noted that the presence of ZrW2O8 in the above-mentioned product obtained in the heat treatment process and ZrW2O7(OH)2(H2O)2 in the above-mentioned precursor obtained in the reaction process can be confirmed by analysis using X-ray diffraction. In X-ray diffraction, for example, a product named SmartLab from Rigaku Corporation can be used as the X-ray diffraction device. As the analysis conditions, measurement using an X-ray tube (Lab device) can be used, set to 40 kV / 30 mA, using a Cu source (Kα), set to θ-2θ measurement, and measurement is performed by the focusing method. In the examples described later, such an X-ray diffraction device and analysis conditions are adopted.

[0058] Examples

[0059] The manufacturing method of zirconium tungstate described above was experimentally implemented, and thus will be described below. However, the description herein is for illustrative purposes only and is not intended to be limiting.

[0060] (Example 1)

[0061] 400 mg of (NH4) 10 W 12 O 41 ·5H2O as a tungsten compound and 273 mg of Zr(SO4)2·4H2O as a zirconium compound were put into an autoclave together with 1,4-butanediol as an organic solvent, and synthesis based on the solvothermal method was carried out. Here, the autoclave was heated on a hot plate, and the heating time was set to 6 hours. The measured temperature of the plate of the hot plate at this time was 156 °C. Using another autoclave with a pressure gauge to investigate the relationship between temperature and pressure, as a result, it was 2 MPa at 200 °C, so it was speculated that the pressure in the autoclave during this reaction was 2 MPa or less. In addition, during the reaction, stirring was carried out at 600 rpm using a cylindrical rotor (Sm·Co). After heating / pressurizing, rapid cooling was carried out in an ice bath.

[0062] The precursor obtained thereby was a grayish-white to light blue solid powder. When analyzed by X-ray diffraction method, the peak of ZrW2O7(OH)2(H2O)2 was confirmed.

[0063] Then, heat treatment of heating the above precursor at 700 °C for 3 hours was carried out to obtain a product. This product was a white solid powder and became Figure 3 the X-ray diffraction pattern (sample) shown in, and zirconium tungstate (ZrW2O8) was generated. In addition, the SEM image of the product after heat treatment is shown in Figure 4 . According to Figure 4 it can be known that: for the product, needle-like products were inhibited, and many granular products were included.

[0064] (Example 2)

[0065] The heating time of the solvothermal method was changed to 8 hours, and the measured temperature of the plate was 161 °C. Except for this, the synthesis and heat treatment of the precursor were carried out in the same manner as in Example 1 to obtain a product. It should be noted that the measured temperature of this plate was of the same degree as that of the plate in Example 1, and it was speculated that the temperature in the pressure-resistant container during the reaction was also approximately the same as that in Example 1. The X-ray diffraction pattern and SEM image of the product obtained thereby are shown in Figure 5 and Figure 6 .

[0066] According to Figure 5 it can be known that: this product also contains zirconium tungstate (ZrW2O8). In addition, according to Figure 6It is known that: in terms of the product, there are more granular products than acicular products.

[0067] (Example 3)

[0068] 11742.7 mg of Na2WO4·2H2O as a tungsten compound was added to 50 mL of distilled water to prepare an aqueous solution of tungstate. In addition, 6325.9 mg of Zr(SO4)2·4H2O as a zirconium compound was added to 50 mL of distilled water to prepare an aqueous solution of zirconium salt. These aqueous solutions were mixed, stirred at 600 rpm at a temperature of 20 °C in an ion exchange solution, filtered by suction and washed with 100 mL of distilled water to obtain a raw material gel.

[0069] Next, 16.4 mass% sulfuric acid was impregnated into the above-mentioned raw material gel, and the raw material gel and 16.4 mass% sulfuric acid were put into an autoclave together, and synthesis based on the DGC method was carried out. Here, distilled water was used as a solvent, the heating time was set to 12 hours, and the set temperature of the autoclave was set to 150 °C. During the reaction in the autoclave, the temperature was considered to be 150 °C, and the pressure was 0.5 MPa according to the vapor pressure curve. After heating / pressurizing, rapid cooling was carried out in an ice bath.

[0070] The precursor obtained thereby was a gray solid, and when analyzed by X-ray diffraction method, the peaks of ZrW2O7(OH)2(H2O)2 were confirmed.

[0071] Then, the above-mentioned precursor was subjected to heat treatment by heating at 600 °C for 3 hours to obtain a product. This product was a white solid and became Figure 7 the X-ray diffraction pattern shown in, and zirconium tungstate (ZrW2O8) was generated. In addition, the SEM image of the product after heat treatment is shown in Figure 8 . According to Figure 8 It is known that: in terms of the product, acicular products were inhibited, and many granular products were included.

[0072] (Example 4)

[0073] A raw material gel was obtained in the same manner as in Example 3. Next, instead of impregnating sulfuric acid into the raw material gel, the raw material gel and an aqueous sulfuric acid solution were put into an autoclave together, and synthesis based on the hydrothermal method was carried out. Here, the heating time was set to 12 hours, and the set temperature of the autoclave was set to 150 °C. During the reaction in the autoclave, the temperature was considered to be 150 °C, and the pressure was 0.5 MPa according to the vapor pressure curve. In addition, during the reaction, stirring was carried out at 600 rpm using a cylindrical rotor (Sm·Co). After heating / pressurizing, rapid cooling was carried out in an ice bath. Such synthesis was carried out when the molar concentration of the above-mentioned aqueous sulfuric acid solution was 1.0 M, 0.5 M, and 0.25 M, and precursors were produced under each condition.

[0074] The resulting precursors were all gray solids, and when analyzed by X-ray diffraction, they became Figure 9 the X-ray diffraction pattern shown in, and the peaks of ZrW2O7(OH)2(H2O)2 were confirmed.

[0075] In addition, the SEM images of the above precursors are shown in Figures 10 to 12 . According to Figures 10 to 12 it can be seen that: for the precursors, the needle-like precursors were inhibited, and many granular precursors were included. Therefore, when heat treatment was performed on the above precursors, it was speculated that granular zirconium tungstate (ZrW2O8) was obtained.

[0076] As described above, according to the above method for manufacturing zirconium tungstate, it can be seen that the needle-like products were inhibited and granular products were obtained.

Claims

1. A method for manufacturing zirconium tungstate, which is a method for manufacturing zirconium tungstate, comprising: A reaction step of heating a raw material containing zirconium and tungsten under pressure in a pressure-resistant container to cause a reaction to obtain a precursor; And A heat treatment step of heating the precursor to obtain a product containing ZrW2O8, In the reaction step, the raw materials are reacted in a state where sulfate ions are present in the pressure-resistant container.

2. The method for manufacturing zirconium tungstate according to claim 1, wherein In the reaction step, an organic solvent is used as a solvent, and the raw materials are reacted in the liquid phase of the organic solvent, The raw materials include a zirconium compound and a tungsten compound, The zirconium compound and the tungsten compound are respectively charged into the pressure-resistant container together with the solvent, and the reaction step is carried out.

3. The method for manufacturing zirconium tungstate according to claim 2, wherein The organic solvent contains diol.

4. The method for manufacturing zirconium tungstate according to claim 2, wherein The organic solvent contains 1,4-butanediol.

5. The method for manufacturing zirconium tungstate according to claim 2, wherein The zirconium compound and / or the tungsten compound contains sulfate.

6. The method for manufacturing zirconium tungstate according to claim 1, wherein In the reaction step, the raw materials are reacted while stirring in the liquid phase of water as a solvent, or the raw materials are reacted in the gas phase containing the vapor of the solvent, The method for manufacturing zirconium tungstate further includes: a gel preparation step of mixing a zirconium compound and a tungsten compound in a liquid and then drying before the reaction step to prepare a raw material gel in which the zirconium compound and the tungsten compound are dispersed, The raw material gel is used as the raw material in the reaction step.

7. The method for manufacturing zirconium tungstate according to claim 6, wherein In the reaction step, sulfuric acid is charged into the pressure-resistant container together with the raw material gel and the solvent.

8. The method for manufacturing zirconium tungstate according to claim 6, wherein The zirconium compound and / or the tungsten compound used in the gel preparation step contains sulfate.

9. The method for manufacturing zirconium tungstate according to claim 6, wherein In the reaction step, the raw materials are reacted in the gas phase containing the vapor of the solvent, The raw material gel is impregnated with sulfuric acid and used in the reaction step.

10. The method for manufacturing zirconium tungstate according to any one of claims 1 to 9, wherein The precursor contains ZrW2O7(OH)2(H2O)2.

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