A spherical nano-tungsten oxide with high specific surface area and preparation method thereof

Abstract

The invention belongs to the technical field of nano tungsten oxide, and specifically relates to a quasi-spherical nano tungsten oxide with a high specific surface area and a preparation method thereof. Carbon black and an ethanol solution are added to an ammonium tungstate solution, and the ethanol solution is used as a dispersant to disperse the carbon black in the ammonium tungstate solution to form a uniform suspension. Under the conditions of continuous stirring and heating, ammonium paratungstate (APT) is promoted to crystallize on the surface of the carbon black to form crystals of ammonium paratungstate coated with carbon black. The APT crystals coated with carbon black are placed in a muffle furnace for high-temperature roasting. During the roasting process, the coated carbon black is converted into carbon dioxide and discharged, and at the same time, the APT crystal structure is destroyed and refined, so as to finally obtain a quasi-spherical nano tungsten oxide with controllable particle size and high specific surface area.

Description

Technical Field

[0001] The invention belongs to the technical field of nano tungsten oxide, and specifically relates to spherical nano tungsten oxide with high specific surface area and a preparation method thereof. Background Art

[0002] In the field of materials science, nano-tungsten oxide is valued for its unique physical and chemical properties. Compared with macroscopic tungsten oxide, the particle size of nano-tungsten oxide is significantly reduced, giving it a higher specific surface area. This property provides abundant active sites for processes such as catalytic reactions and gas adsorption, enhancing the functionality of the material. At the same time, the quantum confinement effect of nano-tungsten oxide has a significant impact on its electronic structure and light absorption characteristics, which is particularly important in optoelectronic devices and energy conversion technologies. In addition to particle size and specific surface area, the microstructure of nano-tungsten oxide also plays a decisive role in its overall performance, including key properties such as mechanical strength and thermal stability.

[0003] At present, there are some shortcomings in the methods of preparing nano-tungsten oxide. Chemical vapor deposition (CVD) has high cost, complex equipment requirements and strict control of reaction conditions, which limits its industrialization process; the sol-gel method has organic residues, which affects the performance of the product, and the particle size will increase during the heat treatment process; the reaction conditions of the hydrothermal synthesis method are difficult to control, and the product performance fluctuates greatly. Therefore, it is of great significance to develop a preparation process for nano-tungsten oxide with simple process flow, controllable particle size and morphology, and high specific surface area to promote the development of nano-tungsten oxide. Summary of the invention

[0004] In order to solve the problems existing in the prior art, the main purpose of the present invention is to provide a spherical nano-tungsten oxide with a high specific surface area and a preparation method thereof.

[0005] To solve the above technical problems, according to one aspect of the present invention, the present invention provides the following technical solutions:

[0006] A method for preparing spherical nano-tungsten oxide with high specific surface area comprises the following steps:

[0007] S1. Add carbon black to the ammonium tungstate solution and add ethanol solution to form a suspension by mechanical stirring;

[0008] S2, placing the suspension in a heat-collecting constant-temperature magnetic stirrer for constant-temperature evaporation and crystallization until a black powder, i.e., a crystal of APT-coated carbon, is completely obtained;

[0009] S3. The black powder is placed in a muffle furnace and calcined to obtain spherical nano-tungsten oxide with a high specific surface area.

[0010] As a preferred embodiment of the method for preparing spherical nano-tungsten oxide with high specific surface area described in the present invention, in step S1, the concentration of the ammonium tungstate solution is 200-300 g / L based on tungsten trioxide.

[0011] As a preferred embodiment of the method for preparing spherical nano-tungsten oxide with high specific surface area described in the present invention, wherein: in the step S1, the molar ratio of carbon black to tungsten trioxide is (1-3):1.

[0012] As a preferred embodiment of the method for preparing spherical nano-tungsten oxide with high specific surface area described in the present invention, in step S1, the concentration of the ethanol solution is 90-100wt%.

[0013] As a preferred embodiment of the method for preparing spherical nano-tungsten oxide with high specific surface area described in the present invention, wherein: in step S1, the volume ratio of the ethanol solution to the ammonium tungstate solution is (1-3):10.

[0014] As a preferred embodiment of the method for preparing spherical nano-tungsten oxide with high specific surface area described in the present invention, in step S2, the constant temperature is 80-100° C., and the magnetic stirring speed is 300-500 r / min.

[0015] As a preferred embodiment of the method for preparing spherical nano-tungsten oxide with high specific surface area described in the present invention, in step S3, the black powder is placed in a corundum ceramic boat, and then placed in a muffle furnace for calcination.

[0016] As a preferred embodiment of the method for preparing spherical nano-tungsten oxide with high specific surface area described in the present invention, wherein: in the step S3, the calcination temperature is 700-1000° C., and the calcination time is 4-8 hours.

[0017] To solve the above technical problem, according to another aspect of the present invention, the present invention provides the following technical solution:

[0018] A spherical nano-tungsten oxide with a high specific surface area is prepared by using the above-mentioned method for preparing the spherical nano-tungsten oxide with a high specific surface area.

[0019] As a preferred embodiment of the spherical nano-tungsten oxide with high specific surface area described in the present invention, the specific surface area of ​​the spherical nano-tungsten oxide with high specific surface area is ≥25m 2 / g, average particle size ≤80nm.

[0020] The beneficial effects of the present invention are as follows:

[0021] The invention provides a spherical nano-tungsten oxide with a high specific surface area and a preparation method thereof. Carbon black and an ethanol solution are added to an ammonium tungstate solution, and the ethanol solution is used as a dispersant to disperse the carbon black in the ammonium tungstate solution to form a uniform suspension. Under the conditions of continuous stirring and heating, ammonium paratungstate (APT) is promoted to crystallize on the surface of the carbon black to form crystals of the carbon black coated with ammonium paratungstate. The APT crystals coated with the carbon black are placed in a muffle furnace for high-temperature roasting. During the roasting process, the coated carbon black is converted into carbon dioxide and discharged, and at the same time, the APT crystal structure is destroyed and refined, so as to finally obtain a spherical nano-tungsten oxide with controllable particle size and a high specific surface area. BRIEF DESCRIPTION OF THE DRAWINGS

[0022] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings required for use in the embodiments or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on the structures shown in these drawings without paying creative work.

[0023] Figure 1 This is a SEM image of nano tungsten oxide prepared in Example 1 of the present invention.

[0024] Figure 2 This is a SEM image of nano tungsten oxide prepared in Comparative Example 1 of the present invention.

[0025] Figure 3 This is a SEM image of nano tungsten oxide prepared in Comparative Example 2 of the present invention.

[0026] The realization of the purpose, functional features and advantages of the present invention will be further explained in conjunction with embodiments and with reference to the accompanying drawings. DETAILED DESCRIPTION

[0027] The following will be described clearly and completely in conjunction with the technical solutions in the embodiments. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0028] According to one aspect of the present invention, the present invention provides the following technical solution:

[0029] A method for preparing spherical nano-tungsten oxide with high specific surface area comprises the following steps:

[0030] S1. Add carbon black to the ammonium tungstate solution and add ethanol solution to form a suspension by mechanical stirring;

[0031] S2, placing the suspension in a heat-collecting constant-temperature magnetic stirrer for constant-temperature evaporation and crystallization until a black powder, i.e., a crystal of APT-coated carbon, is completely obtained;

[0032] S3. The black powder is placed in a muffle furnace and calcined to obtain spherical nano-tungsten oxide with a high specific surface area.

[0033] The present invention simplifies the preparation process of nano tungsten oxide, reduces production costs, improves production efficiency, and has good industrial application prospects; by controlling the amount of carbon black added and the calcination conditions, the controllability of the particle size and morphology of nano tungsten oxide is achieved; spherical nano tungsten oxide with a high specific surface area is prepared, which enhances its application potential in the fields of catalysis, sensors and energy storage.

[0034] Preferably, in step S1, the concentration of the ammonium tungstate solution is 200-300 g / L in terms of tungsten trioxide. Specifically, the concentration may be, for example, any one of 200 g / L, 210 g / L, 220 g / L, 230 g / L, 240 g / L, 250 g / L, 260 g / L, 270 g / L, 280 g / L, 290 g / L, and 300 g / L, or any two thereof.

[0035] Preferably, in step S1, the molar ratio of carbon black to tungsten trioxide is (1-3): 1. Specifically, the molar ratio of carbon black to tungsten trioxide can be, for example, any one of 1:1, 1.5:1, 2:1, 2.5:1, 3:1, or a range between any two thereof.

[0036] Preferably, in step S1, the concentration of the ethanol solution is 90-100wt%. Specifically, the concentration of the ethanol solution may be, for example, any one of 90wt%, 91wt%, 92wt%, 93wt%, 94wt%, 95wt%, 96wt%, 97wt%, 98wt%, 99wt%, 100wt%, or any range between two thereof.

[0037] Preferably, in step S1, the volume ratio of the ethanol solution to the ammonium tungstate solution is (1-3): 10. Specifically, the volume ratio of the ethanol solution to the ammonium tungstate solution can be, for example, any one of 1:10, 1.5:10, 2:10, 2.5:10, 3:10, or a range between any two thereof.

[0038] Preferably, in step S2, the constant temperature is 80-100°C, and the magnetic stirring speed is 300-500 r / min. Specifically, the constant temperature can be, for example, any one of 80°C, 85°C, 90°C, 95°C, 100°C, or a range between any two thereof; the magnetic stirring speed can be, for example, any one of 300 r / min, 350 r / min, 400 r / min, 450 r / min, 500 r / min, or a range between any two thereof.

[0039] Preferably, in step S3, the black powder is placed in a corundum ceramic boat, which is then placed in a muffle furnace for calcination.

[0040] Preferably, in step S3, the calcination temperature is 700-1000°C, and the calcination time is 4-8h. Specifically, the calcination temperature can be, for example, any one of 700°C, 750°C, 800°C, 850°C, 900°C, 950°C, 1000°C, or any range between two thereof; the calcination time can be, for example, any one of 4h, 5h, 6h, 7h, 8h, or any range between two thereof.

[0041] According to another aspect of the present invention, the present invention provides the following technical solution:

[0042] A spherical nano-tungsten oxide with a high specific surface area is prepared by the above-mentioned method for preparing a spherical nano-tungsten oxide with a high specific surface area. The specific surface area of ​​the spherical nano-tungsten oxide with a high specific surface area is ≥25m 2 / g, average particle size ≤80nm.

[0043] The technical solution of the present invention is further described below in conjunction with specific embodiments.

[0044] Example 1

[0045] A method for preparing spherical nano-tungsten oxide with high specific surface area comprises the following steps:

[0046] S1. Add carbon black to the ammonium tungstate solution, and then add ethanol solution, and form a suspension by mechanical stirring; the ammonium tungstate solution is calculated as tungsten trioxide, the concentration is 250g / L, the molar ratio of carbon black to tungsten trioxide is 1:1, the concentration of the ethanol solution is 95wt%, and the volume ratio of the ethanol solution to the ammonium tungstate solution is 2:10;

[0047] S2, placing the suspension in a heat-collecting constant temperature magnetic stirrer for constant temperature evaporation and crystallization, the constant temperature is 100° C., and the magnetic stirring speed is 400 r / min, until a black powder, i.e., a crystal of APT-coated carbon, is completely obtained;

[0048] S3. Place the black powder in a corundum ceramic boat, and then place it in a muffle furnace for calcination at a temperature of 850° C. for 6 hours to obtain spherical nano-tungsten oxide with a high specific surface area.

[0049] The SEM image of the nano-tungsten oxide prepared in this example is as follows: Figure 1 As shown, its specific surface area is 36 m 2 / g, spherical nano-tungsten oxide with an average particle size of 54nm.

[0050] Example 2

[0051] A method for preparing spherical nano-tungsten oxide with high specific surface area comprises the following steps:

[0052] S1. Add carbon black to the ammonium tungstate solution, and then add ethanol solution, and form a suspension by mechanical stirring; the ammonium tungstate solution is calculated as tungsten trioxide, the concentration is 250g / L, the molar ratio of carbon black to tungsten trioxide is 3:1, the concentration of the ethanol solution is 90wt%, and the volume ratio of the ethanol solution to the ammonium tungstate solution is 2:10;

[0053] S2, placing the suspension in a heat-collecting constant-temperature magnetic stirrer for constant-temperature evaporation and crystallization, the constant temperature is 100° C., and the magnetic stirring speed is 400 r / min; until black powder, i.e., crystals of APT-coated carbon, is completely obtained;

[0054] S3. Place the black powder in a corundum ceramic boat, and then place it in a muffle furnace for calcination at a temperature of 850° C. for 6 hours to obtain spherical nano-tungsten oxide with a high specific surface area.

[0055] The nano-tungsten oxide prepared in this example has a specific surface area of ​​40 m 2 / g, spherical nano-tungsten oxide with an average particle size of 43nm.

[0056] Example 3

[0057] A method for preparing spherical nano-tungsten oxide with high specific surface area comprises the following steps:

[0058] S1. Add carbon black to the ammonium tungstate solution, and then add ethanol solution, and form a suspension by mechanical stirring; the ammonium tungstate solution has a concentration of 300 g / L based on tungsten trioxide, a molar ratio of carbon black to tungsten trioxide of 2:1, a concentration of the ethanol solution of 98wt%, and a volume ratio of the ethanol solution to the ammonium tungstate solution of 1:10;

[0059] S2. Place the suspension in a heat-collecting constant temperature magnetic stirrer for constant temperature evaporation and crystallization, with the constant temperature being 90° C. and the magnetic stirring speed being 300 r / min; until a black powder, i.e., a crystal of APT-coated carbon, is completely obtained;

[0060] S3. Place the black powder in a corundum ceramic boat, and then place it in a muffle furnace for calcination at a temperature of 1000° C. for 8 hours to obtain spherical nano-tungsten oxide with a high specific surface area.

[0061] The nano-tungsten oxide prepared in this example has a specific surface area of ​​28 m 2 / g, spherical nano tungsten oxide with an average particle size of 76nm.

[0062] Example 4

[0063] A method for preparing spherical nano-tungsten oxide with high specific surface area comprises the following steps:

[0064] S1. Add carbon black to the ammonium tungstate solution, and then add ethanol solution, and form a suspension by mechanical stirring; the ammonium tungstate solution has a concentration of 200 g / L based on tungsten trioxide, a molar ratio of carbon black to tungsten trioxide of 3:1, a concentration of the ethanol solution of 96wt%, and a volume ratio of the ethanol solution to the ammonium tungstate solution of 3:10;

[0065] S2, placing the suspension in a heat-collecting constant temperature magnetic stirrer for constant temperature evaporation crystallization, the constant temperature is 80°C, and the magnetic stirring speed is 500r / min; until black powder, i.e., crystals of APT-coated carbon, is completely obtained;

[0066] S3. Place the black powder in a corundum ceramic boat, and then place it in a muffle furnace for calcination at a temperature of 700° C. for 4 hours to obtain spherical nano-tungsten oxide with a high specific surface area.

[0067] The nano-tungsten oxide prepared in this example has a specific surface area of ​​42 m 2 / g, spherical nano-tungsten oxide with an average particle size of 37nm.

[0068] Example 5

[0069] A method for preparing spherical nano-tungsten oxide with high specific surface area comprises the following steps:

[0070] S1. Add carbon black to the ammonium tungstate solution, and then add ethanol solution, and form a suspension by mechanical stirring; the ammonium tungstate solution has a concentration of 300 g / L based on tungsten trioxide, a molar ratio of carbon black to tungsten trioxide of 3:1, a concentration of the ethanol solution of 92wt%, and a volume ratio of the ethanol solution to the ammonium tungstate solution of 3:10;

[0071] S2, placing the suspension in a heat-collecting constant temperature magnetic stirrer for constant temperature evaporation crystallization, the constant temperature is 80°C, and the magnetic stirring speed is 500r / min; until black powder, i.e., crystals of APT-coated carbon, is completely obtained;

[0072] S3. Place the black powder in a corundum ceramic boat, and then place it in a muffle furnace for calcination at a temperature of 800° C. for 4 hours to obtain spherical nano-tungsten oxide with a high specific surface area.

[0073] The nano-tungsten oxide prepared in this example has a specific surface area of ​​47 m 2 / g, spherical nano-tungsten oxide with an average particle size of 37nm.

[0074] Example 6

[0075] A method for preparing spherical nano-tungsten oxide with high specific surface area comprises the following steps:

[0076] S1. Add carbon black to the ammonium tungstate solution, and then add ethanol solution, and form a suspension by mechanical stirring; the ammonium tungstate solution has a concentration of 200 g / L based on tungsten trioxide, a molar ratio of carbon black to tungsten trioxide of 1:1, a concentration of the ethanol solution of 100 wt%, and a volume ratio of the ethanol solution to the ammonium tungstate solution of 1:10;

[0077] S2. Place the suspension in a heat-collecting constant temperature magnetic stirrer for constant temperature evaporation and crystallization, with the constant temperature being 90° C. and the magnetic stirring speed being 300 r / min; until a black powder, i.e., a crystal of APT-coated carbon, is completely obtained;

[0078] S3. Place the black powder in a corundum ceramic boat, and then place it in a muffle furnace for calcination at a temperature of 900° C. for 7 hours to obtain spherical nano-tungsten oxide with a high specific surface area.

[0079] The nano-tungsten oxide prepared in this example has a specific surface area of ​​36 m 2 / g, spherical nano-tungsten oxide with an average particle size of 51nm.

[0080] Comparative Example 1

[0081] The difference from Example 1 is that no carbon black is added in step S1.

[0082] The tungsten oxide prepared in this comparative example is Figure 2 As shown, its specific surface area is 2.63 m 2 / g, the average particle size is 162nm, and there are many long strip-shaped tungsten oxide grains in the microstructure.

[0083] Comparative Example 2

[0084] The difference from Example 1 is that the calcination temperature in step S3 is 1200°C.

[0085] The tungsten oxide prepared in this comparative example is Figure 3 As shown, its specific surface area is 5.46 m 2 / g, the average particle size is 116nm, and a large number of large-particle tungsten oxide grains can be seen in the microscopic morphology.

[0086] It can be seen from the above embodiments and comparative examples that the present invention adds carbon black to the ammonium tungstate solution, and adds an ethanol solution, uses the ethanol solution as a dispersant, disperses it into the ammonium tungstate solution to form a uniform suspension, and promotes ammonium paratungstate (APT) to crystallize on the surface of carbon black under continuous stirring and heating conditions to form ammonium paratungstate-coated carbon black crystals, and places the APT crystals coated with carbon black in a muffle furnace for high-temperature calcination. During the calcination process, the coated carbon black is converted into carbon dioxide and discharged, and at the same time, the APT crystal structure is destroyed and refined, and finally a spherical nano-tungsten oxide with controllable particle size and high specific surface area is obtained.

[0087] The above description is only a preferred embodiment of the present invention, and does not limit the patent scope of the present invention. All equivalent structural changes made by using the contents of the present invention specification under the inventive concept of the present invention, or directly / indirectly applied in other related technical fields are included in the patent protection scope of the present invention.

Claims

1. A method for preparing spherical nano-tungsten oxide with high specific surface area, characterized in that: The steps include: S1. Add carbon black to the ammonium tungstate solution and add ethanol solution, and form a suspension by mechanical stirring; the ammonium tungstate solution is calculated as tungsten trioxide, and the molar ratio of carbon black to tungsten trioxide is (1-3):1; S2, placing the suspension in a heat-collecting constant-temperature magnetic stirrer for constant-temperature evaporation and crystallization, until a black powder, i.e., a crystal of ammonium paratungstate-coated carbon, is completely obtained; S3. Place the black powder in a muffle furnace and calcine at a temperature of 700-1000°C to obtain spherical nano-tungsten oxide with a high specific surface area, with a specific surface area of ​​≥25m 2 / g, average particle size ≤80nm.

2. The method for preparing spherical nano-tungsten oxide with high specific surface area according to claim 1, characterized in that: In the step S1, the concentration of the ammonium tungstate solution is 200-300 g / L in terms of tungsten trioxide.

3. The method for preparing spherical nano-tungsten oxide with high specific surface area according to claim 1, characterized in that: In the step S1, the concentration of the ethanol solution is 90-100 wt %.

4. The method for preparing spherical nano-tungsten oxide with high specific surface area according to claim 3, characterized in that: In step S1, the volume ratio of the ethanol solution to the ammonium tungstate solution is (1-3):

10.

5. The method for preparing spherical nano-tungsten oxide with high specific surface area according to claim 1, characterized in that: In step S2, the constant temperature is 80-100° C., and the magnetic stirring speed is 300-500 r / min.

6. The method for preparing spherical nano-tungsten oxide with high specific surface area according to claim 1, characterized in that: In the step S3, the black powder is placed in a corundum ceramic boat, and then placed in a muffle furnace for calcination.

7. The method for preparing spherical nano-tungsten oxide with high specific surface area according to claim 1, characterized in that: In the step S3, the calcination time is 4 to 8 hours.

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