A preparation method of nano indium oxide powder material

Abstract

The invention discloses a preparation method of nano indium oxide powder materials, belonging to the technical field of indium oxide preparation. A mixture of metallic indium and inert particles is placed in an atmosphere furnace for roasting; the atmosphere furnace includes a first temperature zone and a second temperature zone. A gas containing CO<subgt;2< / subgt; is introduced into the first temperature zone, and the temperature is set to 750-900 °C. A gas containing O<subgt;2< / subgt; is introduced into the second temperature zone, and the temperature is set to 950-1050 °C; during the roasting process, the mixture of metallic indium and inert particles is placed in the first temperature zone, and the nano indium oxide product is collected from the second temperature zone. This method directly obtains high-quality nano indium oxide powder materials with small particle size, uniform size and high purity by high-temperature roasting using metallic indium as the raw material. Compared with the existing solvothermal method, the process is simple, the time is short, the yield is high, there is no waste liquid generated, and it is suitable for production using large industrial equipment, which is conducive to realizing industrial production.

Description

Technical Field

[0001] The present invention relates to the technical field of nanopowder preparation, and particularly to a method for preparing nano indium oxide powder materials. Background Art

[0002] Due to its unique physical and chemical properties, nano indium oxide (In2O3) exhibits important application values in the fields of gas sensing, transparent conductive films, solar cells, and catalysis. Its nanoscale size endows it with a high specific surface area and quantum size effect, significantly enhancing the sensitivity and response speed of gas sensors. Meanwhile, it can be made into indium tin oxide as a transparent conductive material to achieve a balance between high light transmittance and conductivity. With the rapid development of the Internet, new energy, and display technologies, the demand for high-performance nano In2O3 continues to grow, gradually becoming a key component driving the development of new functional materials.

[0003] As a commonly used technique for preparing nano In2O3, the solvothermal method promotes the hydrolysis and crystallization of indium precursors through a high-temperature and high-pressure reaction environment, and can synthesize nanoparticles with controllable morphologies. However, this process still has significant defects at present. The reaction needs to maintain a high temperature above 200°C in a closed autoclave for a long time, with a long reaction time, high energy consumption, and demanding requirements for the pressure resistance and sealing of the equipment, greatly increasing the equipment investment and maintenance costs. To control the product size and purity, organic templating agents or surfactants often need to be added during production, resulting in subsequent cumbersome washing and calcination steps, making the production process cumbersome and introducing impurity risks. In addition, indium-containing waste liquid and acidic waste gas may be released during the reaction process, which is likely to cause heavy metal pollution and safety hazards if not properly treated. These factors make it difficult for the solvothermal method to balance high efficiency, environmental friendliness, and low cost, seriously hindering its large-scale application.

[0004] Developing new technologies for preparing nano In2O3 with short process flows, low energy consumption, and environmental friendliness is the direction to break through the industrialization technical bottleneck of nano In2O3. Chinese Patent (Publication No. CN114988460B) discloses a method for an indium oxide nanomaterial and its application. The specific operation is to use indium nitrate tetrahydrate, cobalt salt, terephthalic acid, and N,N-dimethylformamide (DMF) as raw materials, and through solvothermal reaction and calcination treatment, an indium oxide nanomaterial is obtained, which can be used as a gas-sensitive material for hydrogen sulfide gas detection. Chinese Patent (CN117902617A) discloses an indium oxide nanocrystal material and its preparation method, and a catalyst and its preparation method. In this method, in an air atmosphere, an indium source and a reducing agent solution are reacted at a temperature of 140-220°C for 4-48 hours to obtain an indium oxide nanocrystal material, which is used as a catalyst for formic acid production. The two methods disclosed in the above patent technologies have both prepared nano indium oxide products that meet their respective functional requirements. However, in the existing solvothermal method, the reaction process takes a long time, the yield is low, and the generated waste liquid still needs to be further treated. Summary of the Invention

[0005] Aiming at the technical problems existing in the existing preparation technology of nano indium oxide, the purpose of the present invention is to provide a preparation method of nano indium oxide powder material. This method directly obtains high-quality nano indium oxide powder material with small particle size, uniform size and high purity by high-temperature roasting using metallic indium as the raw material. Compared with the existing solvothermal method, the process is simple, the time is short, the yield is high, there is no waste liquid generated, and it is suitable for production using large industrial equipment, which is conducive to realizing industrial production.

[0006] To achieve the above technical purpose, the present invention provides a preparation method of nano indium oxide powder material. In this method, a mixture of metallic indium and inert particles is placed in an atmosphere furnace for roasting; the atmosphere furnace includes a first temperature zone and a second temperature zone. A gas containing CO2 is introduced into the first temperature zone, and the temperature is set at 750 - 900 °C. A gas containing O2 is introduced into the second temperature zone, and the temperature is set at 950 - 1050 °C. During the roasting process, the mixture of metallic indium and inert particles is placed in the first temperature zone, and nano indium oxide product is collected from the second temperature zone.

[0007] The key to the technical solution of the present invention lies in: by strictly controlling the temperature and atmosphere of the two temperature zones in the atmosphere furnace, to achieve the stepwise oxidation, volatilization and deposition of metallic indium, and finally obtain nano indium oxide powder. When the metallic indium raw material is in the first temperature zone, by using the weak oxidizing property of carbon dioxide in the first temperature zone and controlling a relatively low temperature at the same time, it can ensure that the metallic indium raw material is highly selectively oxidized to form low-valent indium oxide, and the low-valent indium oxide is volatile in this temperature range. The low-valent indium oxide migrates to the second temperature zone with the gas flow. By using the strong oxidizing property of oxygen in the second temperature zone and controlling a relatively high temperature range at the same time, to achieve the further oxidation of the low-valent indium oxide to form indium oxide. And the volatilization temperature of indium oxide is high, and within the temperature range controlled in the second temperature zone, it can quickly crystallize and deposit, thus obtaining nano indium oxide powder.

[0008] The temperature of the first temperature zone of the present invention is controlled at 750 - 900 °C, mainly because the oxidation reaction between metallic indium and carbon dioxide starts to occur when the temperature is higher than 750 °C. Appropriately increasing the temperature can accelerate the reaction, but when the temperature is too high, there is a tendency of overoxidation.

[0009] The control of the second temperature zone of the present invention is mainly to achieve the further oxidation of the low-valent indium oxide and provide suitable crystallization conditions for indium oxide. If the temperature is lower than 950 °C, the low-valent indium oxide is prone to disproportionation reaction, resulting in impure deposition products, and too high temperature causes high energy consumption.

[0010] The present invention also employs inert particles, which refer to substances with good physical and chemical stability and do not participate in any reactions under the atmosphere and temperature in the first temperature zone. The introduction of inert particles is very beneficial to improving the oxidation and volatilization efficiency of indium metal. It mainly plays a framework role and can provide support when indium metal melts, ensuring the smooth progress of the oxidation and volatilization reaction of indium metal and preventing insufficient oxidation in some areas due to insufficient oxidizing property, which may lead to incomplete oxidation.

[0011] As a preferred solution, the purity of the indium metal is ≥99.9%. To avoid the possible influence of volatile and oxidizable impurity elements on the final product quality, it is more beneficial to use indium metal raw materials with higher purity.

[0012] As a preferred solution, the mass ratio of the inert particles in the indium metal and inert particle mixture is 50% - 100%. If the proportion of the inert particles is too low, the framework support function of the inert particles cannot be fully exerted, resulting in low oxidation and volatilization efficiency of the molten indium metal, and even insufficient oxidation in some areas, leading to incomplete oxidation and reducing the yield of nano indium oxide. If the proportion of the inert particles is too high, the production efficiency of the nano indium oxide powder will be reduced.

[0013] As a preferred solution, the inert particles include at least one of ceramic particles and quartz particles, and their particle size is not greater than 1 mm. The most preferred inert particle is quartz particle. Quartz particles have a high melting point and are stable under high-temperature roasting systems, and will not affect the oxidation and volatilization of indium metal. The particle size of the inert particles should not be too large, because if the particle size is too large, it is difficult to fully exert its framework pore-forming function. The inert particles are screened by a sieve with a 1 mm mesh aperture, and the undersize material that can pass through the sieve is used.

[0014] As a preferred solution, the volume concentration of CO2 in the CO2-containing gas is 5% - 10%. As a more preferred solution, the flow rate of the CO2-containing gas introduced is 0.05 - 0.1 L / min relative to each gram of indium metal. When the CO2 concentration in the CO2-containing gas is low, the oxidizing property of the atmosphere is insufficient, resulting in the preferential volatilization of indium metal raw materials in the form of indium vapor, which affects the formation of subsequent nano indium oxide. When the CO2 concentration in the CO2-containing gas is high, there is also a tendency of over-oxidation, resulting in the over-oxidation of some indium metal and the inability to be converted into low-boiling-point low-valence oxides for gas-phase volatilization. If the flow rate of the CO2-containing gas is too low, the oxidation and volatilization efficiency is low. If the flow rate of the CO2-containing gas is too high, it will also cause the over-oxidation of some indium metal and make it difficult to volatilize as low-valence oxides in the gas phase.

[0015] As a preferred solution, the volume concentration of O2 in the O2-containing gas is 5% - 12%. As a more preferred solution, the feeding flow rate of the O2-containing gas is 0.04 - 0.09 L / min per gram of indium metal. When the concentration of oxygen in the O2-containing gas is too low, disproportionation reaction of some lower-valent indium oxides will occur, resulting in impure indium oxide. When the concentration of oxygen in the O2-containing gas is too high, it will also cause waste of resources and does not significantly improve the reaction effect. Similarly, when the flow rate of the O2-containing gas is too small, the oxidation atmosphere is insufficient and the reaction efficiency is low. When the flow rate of the O2-containing gas is too large, after the flow rate exceeds the upper limit of the reaction rate, it will no longer have a positive impact on the reaction.

[0016] Compared with the prior art, the beneficial technical effects brought by the technical solution of the present invention are as follows:

[0017] (1) The method for preparing nano indium oxide powder material proposed by the present invention uses indium metal as the raw material and can directly obtain high-quality nano indium oxide powder material only through the roasting process. The technical route is simple to operate, greatly reducing the production cost of enterprises and meeting the industrial requirements.

[0018] (2) The method for preparing nano indium oxide powder material proposed by the present invention can be realized by using existing mature industrial equipment, such as a laboratory atmospheric-pressure atmosphere roasting furnace, or rotary kiln, reduction shaft furnace and other mature large-scale industrial equipment can be used in larger-scale industrial production. The technical route is simple, greatly improving the production efficiency of nano indium oxide powder material and reducing the production cost.

[0019] (3) The method for preparing nano indium oxide powder material proposed by the present invention makes full use of the advantage that lower-valent indium oxides are easy to volatilize. Under weak oxidation atmosphere and low temperature conditions, indium metal is volatilized in the form of lower-valent oxides, and then the lower-valent indium oxides are further introduced into a strong oxidation atmosphere and high temperature conditions, so that the gaseous lower-valent oxides are rapidly oxidized to form nano indium oxide crystals. The obtained nano indium oxide powder has uniform particle size, is fine enough, and has high purity, and can be used in multiple fields such as catalysis and gas sensing. Description of the Drawings

[0020] Figure 1 It is the scanning electron microscope image of the nano indium oxide powder prepared in Example 1. Detailed Embodiments

[0021] The following examples are intended to further illustrate the content of the present invention rather than limit the protection scope of the claims of the present invention.

[0022] Comparative Example 1

[0023] This comparative example shows that if the addition amount of quartz is insufficient, the volatilization rate is low.

[0024] Compared with Example 1, the only difference is that indium metal and quartz particles are evenly mixed, and the addition amount of quartz is 20%.

[0025] Performance testing was carried out on the product: the purity of indium oxide was 99.99%, the average particle size was 77.5 nm, the distribution was uniform, and the indium recovery rate was only 47.3%.

[0026] Comparative Example 2

[0027] This comparative example shows that if the roasting temperature in the volatilization section is low, the volatilization rate is low.

[0028] Compared with Example 1, the only difference is that the roasting temperature in the first stage is 500 °C.

[0029] Performance testing was carried out on the product: the purity of indium oxide was 99.99%, the average particle size was 78.6 nm, the distribution was uniform, and the indium recovery rate was only 32.7%.

[0030] Comparative Example 3

[0031] This comparative example shows that if the concentration of CO2 in the roasting gas in the volatilization section is low, part of the indium volatilizes in the form of indium vapor, affecting the product purity.

[0032] Compared with Example 1, the only difference is that the concentration of CO2 in the roasting atmosphere during the first-stage roasting process is 3%.

[0033] Performance testing was carried out on the product: the purity of indium oxide was only 62.8%, the average particle size was 77.3 nm, the distribution was uniform, and the indium recovery rate was only 72.7%.

[0034] Comparative Example 4

[0035] This comparative example shows that if the roasting temperature in the deposition section is too low, part of the indium deposits in the form of metallic indium, and the grain growth is uneven.

[0036] Compared with Example 1, the only difference is that the roasting temperature in the second-stage deposition area is 800 °C.

[0037] Performance testing was carried out on the product: the purity of indium oxide was only 53.8%, the average particle size was 157.2 nm, the distribution was uneven, and the indium recovery rate was 93.2%.

[0038] Comparative Example 5

[0039] This comparative example shows that if the gas concentration in the deposition area is low, it is not conducive to secondary oxidation.

[0040] Compared with Example 1, the only difference is that the concentration of O2 in the roasting atmosphere in the second-stage deposition area is 2%.

[0041] Perform performance testing on the product: The purity of indium oxide is only 46.9%, the average particle size is 88.1 nm, the distribution is uneven, and the indium recovery rate is 94.9%.

[0042] Example 1

[0043] Using metallic indium (purity 99.9%) and quartz particles (100% passing through a 1 mm sieve) as raw materials. First, mix the metallic indium and quartz particles evenly, with the addition amount of quartz being 50%. Place the mixture in an atmosphere furnace for roasting. The roasting temperature in the first stage is 750 °C, the CO2 concentration is 5%, and the flow rate is 0.1 L·min -1 For each gram of raw material, weakly oxidize the raw material to volatilize indium in the form of low-valent oxides. In the second-stage deposition area, the roasting temperature is 1050 °C, the O2 concentration is 5%, and the flow rate is 0.09 L·min -1 For each gram of raw material, pass through to oxidize the low-valent indium oxide to indium oxide, and collect the deposition product in the second-stage temperature zone as the nano indium oxide product.

[0044] Perform performance testing on the product. The purity of indium oxide is 99.99%, the average particle size is 79.3 nm, the distribution is uniform, and the indium recovery rate is 95.2%.

[0045] Example 2

[0046] Using metallic indium (purity 99.9%) and quartz particles (100% passing through a 1 mm sieve) as raw materials. First, mix the metallic indium and quartz particles evenly, with the addition amount of quartz being 100%. Place the mixture in an atmosphere furnace for roasting. The roasting temperature in the first stage is 750 °C, the CO2 concentration is 5%, and the flow rate is 0.1 L·min -1 For each gram of raw material, weakly oxidize the raw material to volatilize indium in the form of low-valent oxides. In the second-stage deposition area, the roasting temperature is 1050 °C, the O2 concentration is 10%, and the flow rate is 0.09 L·min -1 For each gram of raw material, pass through to oxidize the low-valent indium oxide to indium oxide, and collect the deposition product in the second-stage temperature zone as the nano indium oxide product.

[0047] Perform performance testing on the product. The purity of indium oxide is 99.97%, the average particle size is 83.9 nm, the distribution is uniform, and the indium recovery rate is 96.7%.

[0048] Example 3

[0049] Using metallic indium (purity 99.9%) and quartz particles (100% passing through a 1 mm sieve) as raw materials. First, mix the metallic indium and quartz particles evenly, with the addition amount of quartz being 80%. Place the mixture in an atmosphere furnace for roasting. The roasting temperature in the first stage is 900 °C, the CO2 concentration is 10%, and the flow rate is 0.1 L·min -1For each gram of raw material, the raw material is weakly oxidized to volatilize indium in the form of low-valent oxides. In the second-stage deposition area, the roasting temperature is 1050 °C, the O2 concentration is 10%, and the flow rate is 0.09 L·min -1 For each gram of raw material, oxygen is introduced to oxidize the low-valent indium oxide to indium oxide, and the deposition product in the second temperature zone is collected as the nano-indium oxide product.

[0050] The performance of the product is tested. The purity of indium oxide is 99.99%, the average particle size is 82.1 nm, the distribution is uniform, and the indium recovery rate is 96.2%.

[0051] Example 4

[0052] Using metallic indium (purity 99.9%) and quartz particles (100% passing through a 1 mm sieve) as raw materials. First, the metallic indium and quartz particles are mixed evenly, with the quartz addition amount being 80%. The mixture is placed in an atmosphere furnace for roasting. The roasting temperature in the first stage is 900 °C, the CO2 concentration is 10%, and the flow rate is 0.05 L·min -1 For each gram of raw material, the raw material is weakly oxidized to volatilize indium in the form of low-valent oxides. In the second-stage deposition area, the roasting temperature is 950 °C, the O2 concentration is 12%, and the flow rate is 0.04 L·min -1 For each gram of raw material, oxygen is introduced to oxidize the low-valent indium oxide to indium oxide, and the deposition product in the second temperature zone is collected as the nano-indium oxide product.

[0053] The performance of the product is tested. The purity of indium oxide is 99.98%, the average particle size is 72.8 nm, the distribution is uniform, and the indium recovery rate is 95.7%.

[0054] Example 5

[0055] Using metallic indium (purity 99.9%) and alumina ceramic particles (100% passing through a 0.8 mm sieve) as raw materials. First, the metallic indium and alumina ceramic particles are mixed evenly, with the ceramic addition amount being 80%. The mixture is placed in an atmosphere furnace for roasting. The roasting temperature in the first stage is 800 °C, the CO2 concentration is 8%, and the flow rate is 0.05 L·min -1 For each gram of raw material, the raw material is weakly oxidized to volatilize indium in the form of low-valent oxides. In the second-stage deposition area, the roasting temperature is 1000 °C, the O2 concentration is 10%, and the flow rate is 0.04 L·min -1 For each gram of raw material, oxygen is introduced to oxidize the low-valent indium oxide to indium oxide, and the deposition product in the second temperature zone is collected as the nano-indium oxide product.

[0056] The performance of the product is tested. The purity of indium oxide is 99.91%, the average particle size is 70.2 nm, the distribution is uniform, and the indium recovery rate is 95.4%.

Claims

1. A preparation method of nano indium oxide powder material, characterized in that: Place the mixture of indium metal and inert particles in an atmosphere furnace for roasting; the atmosphere furnace includes a first temperature zone and a second temperature zone. A gas containing CO2 is introduced into the first temperature zone, and the temperature is set to 750 - 900 °C. A gas containing O2 is introduced into the second temperature zone, and the temperature is set to 950 - 1050 °C. During the roasting process, the mixture of indium metal and inert particles is placed in the first temperature zone, and nano indium oxide products are collected from the second temperature zone; The mass ratio of the inert particles in the mixture of indium metal and inert particles is 50% - 100%; The volume concentration of CO2 in the gas containing CO2 is 5% - 10%; The volume concentration of O2 in the gas containing O2 is 5% - 12%.

2. The preparation method of a nano-indium oxide powder material according to claim 1, wherein: The purity of the indium metal is ≥99.9%; 3. The preparation method of a nano indium oxide powder material according to claim 1, characterized in that: The inert particles include at least one of ceramic particles and quartz particles, and their particle size is not greater than 1 mm; 4. The preparation method of a nano indium oxide powder material according to claim 1, characterized in that: The flow rate of the gas containing CO2 introduced is 0.05 - 0.1 L / min relative to each gram of indium metal; 5. The preparation method of a nano indium oxide powder material according to claim 1, characterized in that: The flow rate of the gas containing O2 introduced is 0.04 - 0.09 L / min relative to each gram of indium metal.

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