Preparation method of high-purity tubular bismuth oxide

Abstract

The invention discloses a preparation method of high-purity tubular bismuth oxide, the preparation method is based on the effect of bismuth nitrate crystal and alkaline additive in water to transform morphology, and self-made cracking equipment is utilized to ensure that the product is uniformly heated and fully cracked, and finally the high-quality tubular bismuth oxide crystal with high yield, uniform texture and stable performance is obtained. The method is suitable for industrial production and has a wide application prospect.

Description

Technical Field

[0001] The invention relates to the technical field of semiconductor material preparation, in particular to a method for preparing high-purity tubular bismuth oxide. Background Art

[0002] Bismuth oxide (Bi2O3), as an important semiconductor material, has attracted widespread attention due to its potential applications in various fields. It shows unique advantages in photocatalysis, solid oxide fuel cell electrolytes, oxygen sensors, etc. High-purity bismuth oxide is a light yellow solid powder with a purity of more than 99.999%. Its significance lies in improving the performance and application efficiency of bismuth oxide materials. High-purity bismuth oxide has better chemical stability and longer service life. In certain specific high-tech fields, such as high-precision infrared detection technology, the purity of materials is extremely high. Only high-purity bismuth oxide can meet the standards of these fields. Researching and developing the synthesis method of high-purity bismuth oxide not only expands its application fields and enhances market competitiveness, but also conforms to development trends and promotes scientific research development. It is of great significance to promote the progress of materials science and realize innovation in material applications.

[0003] Bismuth oxide can also further improve its photocatalytic performance through special morphology design, such as ultra-thin structure, hierarchical structure and hollow structure. The most common morphology is thin film type. These special structures can increase the specific surface area of ​​the catalyst, improve the light absorption capacity, and enhance the contact between the catalyst and pollutants, thereby improving the photocatalytic efficiency.

[0004] Tubular bismuth oxide has the characteristics of large specific surface area, high electron migration efficiency, and excellent optical properties. It has shown a wider application prospect in the manufacture of high-sensitivity sensors, high-performance electronic devices, energy, medical treatment, environmental purification and other fields. In future research and applications, further exploration and optimization of the performance of tubular bismuth oxide will bring more possibilities for scientific and technological progress and social development.

[0005] At present, the main methods for preparing bismuth oxide are solution precipitation, arc melting, and solid-state synthesis. The arc method uses expensive equipment and is not suitable for large-scale industrial production; the solution precipitation method and solid-state synthesis method are complex to operate, have a long production cycle, and the obtained products are unstable and of low purity.

[0006] Therefore, it is necessary to propose a method for preparing high-purity tubular bismuth oxide. Summary of the invention

[0007] The present invention aims to provide a method for preparing high-purity tubular bismuth oxide, so as to overcome the defects of the prior art such as high cost, long production cycle, unstable product and low purity.

[0008] In view of this, the scheme of the present invention is:

[0009] A method for preparing high-purity tubular bismuth oxide, comprising the steps of:

[0010] S1. After bismuth nitrate crystals are dispersed in an aqueous solution, an alkaline auxiliary agent is added to react fully, and a precipitate is obtained by washing and filtering;

[0011] S2. The obtained precipitate is washed and then cracked at 350-800° C. for 2-8 hours to obtain high-purity tubular bismuth oxide crystals.

[0012] Further, the alkaline auxiliary agent is selected from at least one of citrate, sodium hydroxide, potassium hydroxide, and ammonium hydroxide;

[0013] Preferably, in step S1, the molar ratio of the bismuth nitrate crystals to the alkaline auxiliary agent is 1:(0.2-1.5).

[0014] Furthermore, in step S1, the mass ratio of the bismuth nitrate crystal solution to water is 1:(5-40).

[0015] Furthermore, in step S1, the solvent used in the washing process is one or more of deionized water, ethanol, and hydrogen peroxide.

[0016] Furthermore, in step S1, the bismuth nitrate crystals are obtained by recrystallization of industrial bismuth nitrate or concentrated crystallization of industrial bismuth nitrate solution. Preferably, the concentrated crystallization process is controlled at a temperature of 80 to 200°C.

[0017] Furthermore, in step S2, the cracking process uses a cracking tube, the cracking tube rotates axially during the cracking process, and an oxidizing gas is passed axially through the cracking tube; the oxidizing gas can be purified air or oxygen.

[0018] Preferably, the flow rate of the oxidizing gas is 0.02 to 1 L / min.

[0019] Preferably, the cracking tube is made of one of platinum, alumina, zirconium oxide, boron nitride and quartz.

[0020] Compared with the prior art, the present invention has the following beneficial effects:

[0021] The preparation method of high-purity tubular bismuth oxide of the present invention is obtained by reacting crystals with alkaline additives to transform the morphology and taking precipitates for cracking. Compared with the gas phase method, the obtained bismuth oxide is tubular, and the total amount of impurities is controlled below 0.5ppm. The purity is high, and the high performance requirements of the tubular bismuth oxide are met. The method is suitable for industrial production and has broad application prospects.

[0022] The preparation method of the present invention does not require complicated equipment, has good stability, a large single feeding amount, high efficiency, and a yield rate close to 100%, thereby greatly reducing production costs. BRIEF DESCRIPTION OF THE DRAWINGS

[0023] Figure 1 Schematic diagram of the cracking device used in the preparation method of the present invention.

[0024] Figure 2 This is a SEM image of high-purity tubular bismuth oxide obtained by the preparation method of the present invention.

[0025] Figure 1 In the figure: 1 is a heating jacket; 2 is an air inlet pipe; 3 is a cracking tube; 4 is a rotating shaft; 5 is an air outlet pipe; K1 is valve one, and K2 is valve two. DETAILED DESCRIPTION

[0026] The technical solution of the present invention will be clearly and completely described and verified in conjunction with the preferred embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of them. 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.

[0027] In one embodiment, a method for preparing high-purity tubular bismuth nitrate is provided, comprising the steps of:

[0028] 1) After bismuth nitrate crystals are dispersed in an aqueous solution, an alkaline auxiliary agent is added to fully react, and a precipitate is obtained by washing and filtering; the alkaline auxiliary agent is selected from at least one of citrate, sodium hydroxide, potassium hydroxide, and ammonium hydroxide;

[0029] 2) The obtained precipitate is washed and then placed in a cracking device for cracking. The cracking device includes a cracking tube, which rotates axially during the cracking process. An oxidizing gas is passed through the cracking tube axially. The oxidizing gas can be purified air or oxygen. The cracking device is cracked at 350-800° C. for 2-8 hours to obtain high-purity tubular bismuth oxide crystals.

[0030] In the above embodiment, the preparation method is to transform the morphology by reacting the crystal with an alkaline auxiliary agent and taking the precipitate for cracking, which has obvious cost advantages over the gas phase method. The obtained bismuth oxide is tubular, and the total amount of impurities is controlled below 0.5 ppm. The purity is high, which meets the high performance requirements of tubular bismuth oxide and is suitable for industrial production.

[0031] In a preferred embodiment, the material of the cracking tube is one of platinum, alumina, zirconium oxide, boron nitride, and quartz; and the flow rate of the oxidizing gas is 0.02 to 1 L / min.

[0032] In a preferred embodiment, in step S1, the molar ratio of the bismuth nitrate crystals to the alkaline auxiliary agent is 1:(0.2-1.5). The addition of the alkaline auxiliary agent helps to transform the morphology of the crystals, thereby forming a stable tubular structure during the cracking process.

[0033] In a preferred embodiment, in step S1, the mass ratio of the bismuth nitrate crystals to water is 1:(5-40).

[0034] In a preferred embodiment, in step S1, the solvent used in the washing process is one or more of deionized water, ethanol, and hydrogen peroxide.

[0035] In a preferred embodiment, in step S1, the bismuth nitrate crystals are obtained by recrystallization of industrial bismuth nitrate or concentrated crystallization of industrial bismuth nitrate solution. Preferably, the recrystallization or concentrated crystallization is carried out from a dilute nitric acid solution, and the concentrated crystallization process is controlled at a temperature of 80 to 200° C. The crystallization can remove a small portion of water-soluble impurities.

[0036] In the above embodiment, the scanning electron microscope image of the finally obtained high-purity tubular bismuth oxide is as follows: Figure 2 As shown, it can be confirmed that the product obtained by the above preparation method is tubular with a diameter of 8-12 μm.

[0037] In a preferred embodiment, the lysis device is as follows Figure 1 As shown, it includes a heating jacket 1 for controlling the cracking temperature, a cracking tube 3 placed inside the heating jacket 1, and a rotating shaft 4 axially passed through the cracking tube 3 for driving the cracking tube 3 to rotate in the axial direction. The rotating shaft 4 is provided with an inlet pipe 2 passed into the cracking tube 3, and an outlet pipe 5 for passing and discharging oxidizing gas into the cracking tube 3; the inlet pipe 2 and the outlet pipe 5 are respectively provided with a valve 1 K1 and a valve 2 K2 for controlling the gas flow rate to achieve a better cracking effect.

[0038] The following is a preferred implementation example. The bismuth nitrate solution is a solution of bismuth nitrate dissolved in dilute nitric acid, with a mass fraction of 25-35%. The bismuth nitrate used is from the same batch. If the manufacturer of the reagent or instrument is not indicated in the example, conventional products can be purchased from the market. If no specific conditions are indicated, conventional conditions or conditions recommended by the manufacturer can be used.

[0039] Example 1

[0040] This embodiment provides a method for preparing high-purity tubular bismuth oxide, comprising the following steps:

[0041] 1) heating the bismuth nitrate solution to 100° C. to concentrate and crystallize to obtain crystals;

[0042] 2) Take 150 g of the crystals obtained by crystallization, add 1 kg of water to disperse, add 25 g of sodium citrate while stirring, react for 20 min, add ethanol to wash, and filter to obtain a precipitate;

[0043] 3) After washing the precipitate, the precipitate is placed in a cracking device at 450° C. for cracking for 6 hours, oxygen is introduced during the cracking process, and the inlet and outlet gas flow rates of the cracking process are controlled to be 0.05 L / min; finally, high-purity tubular bismuth oxide crystals are obtained.

[0044] Example 2

[0045] This embodiment provides a method for preparing high-purity tubular bismuth oxide, comprising the following steps:

[0046] 1) heating the bismuth nitrate solution to 150° C. and concentrating and crystallizing;

[0047] 2) Take 150g of the crystals obtained by crystallization, add 2.5kg of water to disperse, add 5g of sodium hydroxide while stirring, react for 20min, add hydrogen peroxide to wash, and filter to obtain a precipitate;

[0048] 3) After washing the precipitate, the precipitate is placed in a cracking device at 600° C. for 3 hours, oxygen is introduced during the cracking process, and the inlet and outlet gas flow rates of the cracking process are controlled to be 0.6 L / min; finally, high-purity tubular bismuth oxide crystals are obtained.

[0049] Example 3

[0050] This embodiment provides a method for preparing high-purity tubular bismuth oxide, comprising the following steps:

[0051] 1) heating the bismuth nitrate solution to 200° C. for concentration and crystallization;

[0052] 2) Take 150g of the crystals obtained by crystallization, add 3kg of water to disperse, add 15g of ammonium hydroxide while stirring, react for 20min, add deionized water to wash, and filter to obtain a precipitate;

[0053] 3) After washing the precipitate, the precipitate is placed in a pyrolysis device and pyrolyzed at 750° C. for 3 h. Oxygen is introduced during the pyrolysis process, and the inlet and outlet gas flow rates during the pyrolysis process are controlled to be 0.2 L / min; finally, high-purity tubular bismuth oxide crystals are obtained.

[0054] Comparative Example 1

[0055] The preparation method does not include step 2), and the bismuth nitrate crystals are directly cracked. The other steps and conditions are the same as those in Example 1.

[0056] Comparative Example 2

[0057] The alkaline auxiliary agent in step 2) was replaced with 25 g of aqueous ammonia, and the other steps and conditions were the same as those in Example 1.

[0058] Comparative Example 3

[0059] The amount of sodium hydroxide in step 2) was increased to 30 g, and the other steps and conditions were the same as in Example 2.

[0060] Experimental example

[0061] The purity of the tubular bismuth oxide obtained by cracking the above Examples 1-3 was tested to be above 99.9995% in bismuth oxide content. The bismuth oxide content in Comparative Examples 1-2 was all lower than 99.9995%.

[0062] The ICP test results of the final products of the above Examples 1-3 and Comparative Examples 1-2, as well as the crystal morphology observation results using a scanning electron microscope are shown in Table 1.

[0063] Table 1:

[0064]

[0065] It is not difficult to see from Table 1 that Examples 1-3 use a crystallization method to remove impurities. During the precipitation process, a precipitation aid is used to transform the morphology, and a homemade cracking device is used to ensure that the product is evenly heated and fully cracked, and finally obtains high-quality tubular bismuth oxide crystals with high yield, uniform texture, and stable performance. In Comparative Example 1, bismuth nitrate crystals are directly used for cracking, and the impurity content and bismuth oxide morphology of the product bismuth oxide do not meet the requirements; when ammonia water is used as an auxiliary agent in Comparative Example 2, dendritic bismuth oxide is finally cracked, and in Comparative Example 3, excessive sodium hydroxide auxiliary agent is used to generate blocky bismuth oxide, indicating that the selection and dosage of the auxiliary agent have a greater impact on the transformation of the crystal morphology, so that a tubular product that meets the requirements cannot be obtained.

[0066] Although embodiments of the present invention have been shown and described, it will be appreciated by those skilled in the art that various changes, modifications, substitutions and variations may be made to the embodiments without departing from the principles and spirit of the present invention, and that the scope of the present invention is defined by the appended claims and their equivalents.

Claims

1. A method for preparing high-purity tubular bismuth oxide, characterized in that the steps include: S1. After the bismuth nitrate crystals and the alkaline auxiliary agent are fully reacted in water, the precipitate is obtained by washing and filtering; S2. The obtained precipitate is washed and then cracked at 350-800° C. for 2-8 hours to obtain high-purity tubular bismuth oxide crystals.

2. The preparation method according to claim 1, characterized in that: The alkaline auxiliary agent is selected from at least one of citrate, sodium hydroxide, potassium hydroxide and ammonium hydroxide.

3. The preparation method according to claim 2, characterized in that: In step S1, the molar ratio of the bismuth nitrate crystals to the alkaline auxiliary agent is 1:(0.2-1.5).

4. The preparation method according to claim 1, characterized in that: In step S1, the mass ratio of the bismuth nitrate crystals to water is 1:(5-40).

5. The preparation method according to claim 1, characterized in that: In step S1, the washing process uses a solvent selected from the group consisting of deionized water, ethanol, and hydrogen peroxide.

6. The preparation method according to claim 1, characterized in that: In step S1, the bismuth nitrate crystals are obtained by recrystallization of industrial bismuth nitrate or concentrated crystallization of industrial bismuth nitrate solution.

7. The preparation method according to claim 1, characterized in that: The concentration and crystallization process is controlled at a temperature of 80-200°C.

8. The preparation method according to claim 1, characterized in that: In step S2, the cracking process uses a cracking tube, the cracking tube rotates axially during the cracking process, and an oxidizing gas is passed axially through the cracking tube.

9. The preparation method according to claim 8, characterized in that: The oxidizing gas flow rate is 0.02 to 1 L / min.

10. The preparation method according to claim 8, characterized in that: The cracking tube is made of one of platinum, alumina, zirconium oxide, boron nitride and quartz.

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