A method for preparing porous indium powder

Abstract

This invention relates to a method for preparing porous indium powder. The method uses indium nitrate tetrahydrate as the indium source, 2-aminoterephthalic acid as the main ligand, and 1-butylimidazole as the auxiliary ligand, dissolved sequentially in N,N-dimethylformamide at a molar ratio of 1:(1.2-1.5):(0.1-0.2). Indium-based MOF powder is synthesized through a stepwise high-pressure reaction. The MOF powder is then placed in an argon-hydrogen mixed gas atmosphere and reduced by stepwise temperature increases to prepare a composite precursor indium particles embedded in a carbon matrix. Finally, the composite precursor indium particles embedded in the carbon matrix is ​​dispersed in an acetic acid and citric acid etching solution, intermittently ultrasonically etched, filtered, washed, and dried to obtain porous indium powder. This invention can improve the specific surface area and ion / electron transport efficiency of indium powder, reduce oxygen content, and reduce indium powder agglomeration, thereby improving the adsorption performance and catalytic activity of indium powder.

Description

Technical Field

[0001] This invention belongs to the field of non-ferrous metal powder material preparation technology, specifically relating to a method for preparing porous indium powder. Background Technology

[0002] Indium is a rare and dispersed metal with good ductility and malleability. It can form type III-V compounds with group VB elements and is a key material for emerging fields such as semiconductors, next-generation optoelectronic displays, new energy, and 5G communications, embodying new productivity. Among various types of indium products, indium powder is widely used in silicon solar cells and dental filling materials, bearing alloys, low-melting-point alloys, corrosion-resistant alloys, dental alloys and alloy coatings, solders, lead-free solder pastes, and other organic synthetic materials, showing a very broad application prospect. Currently, the main methods for preparing indium powder include electrolysis, distillation, ultrasonic atomization, and monovalent indium ion disproportionation. The indium powder prepared is mostly solid particles, which have problems such as small specific surface area, low ion / electron transport efficiency, high oxygen content, and easy agglomeration. Summary of the Invention

[0003] The purpose of this invention is to overcome the shortcomings of the prior art and provide a method for preparing porous indium powder to increase the specific surface area of ​​indium powder, optimize ion / electron transport efficiency and reduce oxygen content by improving the sphericity of indium powder, and at the same time reduce indium powder agglomeration, thereby improving the adsorption performance and catalytic activity of indium powder.

[0004] To achieve the above objectives, the present invention adopts the following technical solution: A method for preparing porous indium powder includes the following steps: (1) Synthesis of indium-based MOF material: Indium nitrate tetrahydrate and 2-aminoterephthalic acid were added sequentially to N,N-dimethylformamide. After the indium nitrate tetrahydrate and 2-aminoterephthalic acid were completely dissolved, 1-butylimidazolium was added and stirred to obtain a mixed solution. The mixed solution was transferred to a high-pressure reactor and the pressure was maintained at 0.8~1.2MPa. The reaction was carried out at 80℃ for 4-6h and at 100-120℃ for 8-12h. After the reaction was completed, the mixture was naturally cooled to room temperature, washed with ethanol, and then vacuum dried to obtain indium-based MOF powder. (2) In-situ reduction preparation of indium-carbon composite precursor: The indium-based MOF material obtained in step (1) is placed in a reduction furnace, and a reducing gas is introduced. The temperature is first raised to 180-220°C at 2-5°C / min and held for 20-40 minutes. Then, the temperature is raised to 320-420°C at 1-3°C / min and held for 2-4 hours. The reducing atmosphere is kept circulating and the material is naturally cooled to room temperature to obtain a composite precursor in which indium particles are embedded in a carbon matrix. (3) Controllable etching: The composite precursor obtained in step (2) is dispersed in the etching solution at a solid-liquid ratio of 1:5-20 (g:mL), placed in an ultrasonic cleaner, and intermittently ultrasonically etched at room temperature for 4-8 hours. After etching, it is filtered, washed, and vacuum dried to obtain porous indium powder.

[0005] Further, in step (1), the molar ratio of indium nitrate tetrahydrate: 2-aminoterephthalic acid: 1-butylimidazole is 1:(1.2-1.5):(0.1-0.2).

[0006] Furthermore, the reducing gas in step (2) is a mixture of hydrogen and argon, wherein the volume percentage of hydrogen is 5%-15% and the gas flow rate is 20-40 mL / min.

[0007] Further, the etching solution in step (3) is composed of 0.5 mol / L acetic acid and 0.1 mol / L citric acid in a volume ratio of 1:0.8~1.2.

[0008] Furthermore, the ultrasonic frequency of the intermittent ultrasonic etching in step (3) is 40kHz, and the intermittent mode is ultrasonic for 5-10 minutes and then paused for 2-4 minutes.

[0009] The method of the present invention has the following beneficial effects: 1. This invention uses indium nitrate tetrahydrate as the indium source, 2-aminoterephthalic acid as the main ligand (chain length approximately 0.8-1.0 nm), and 1-butylimidazole as the auxiliary ligand (chain length approximately 0.4-0.5 nm). These are sequentially dissolved in N,N-dimethylformamide in a predetermined ratio. The morphology of the MOF template is controlled by the difference in chain length between the main and auxiliary ligands, ensuring that the particle morphology of the MOF template matches the application requirements of the target porous indium powder. Indium-based MOFs are synthesized using an organic ligand (2-aminoterephthalic acid) containing reducing functional groups. Furthermore, the synergistic reduction effect of the ligand functional groups and hydrogen is utilized to reduce the reduction temperature and hydrogen consumption, while simultaneously inhibiting indium particle agglomeration.

[0010] 2. Based on the unique structure of MOF pyrolytic carbon, which has "many defects, weak interfaces, and good dispersion", a composite precursor indium particles embedded in a carbon matrix is ​​etched with acid. Through the synergistic mechanism of "citric acid targeting adsorption of the carbon matrix and acetate protons weakening the carbon-indium interface, and fluid shear force in ultrasonic cleaning peeling off carbon flakes", the carbon matrix is ​​peeled off to obtain porous indium powder with high purity and uniform particle size.

[0011] 3. The prepared porous indium powder has a specific surface area of ​​50-200 m² / g, sphericity >90%, and oxygen content ≤50 ppm. It has excellent adsorption performance and catalytic activity and can be applied to various scenarios such as sensing and catalysis.

[0012] This invention achieves precise control of the structure and function of indium powder through a multi-step synergistic reaction, which involves ligand synergistic regulation of MOF morphology, step-heating matching of reduction characteristics, and etching with a weak acid composite system. Detailed Implementation

[0013] The present invention will now be described in detail with reference to the embodiments, but the scope of protection of the present invention is not limited to the contents described in the embodiments.

[0014] Unless otherwise specified, the various operating methods described in the embodiments are conventional methods in the art. Unless otherwise specified, the materials and equipment used in the following embodiments are commercially available. Example 1

[0015] A method for preparing porous indium powder, comprising the following steps: (1) Synthesis of indium-based MOF material: 10.0 g of indium nitrate tetrahydrate and 5.3 g of 2-aminoterephthalic acid were added sequentially to 500 mL of N,N-dimethylformamide. After N,N-dimethylformamide and 2-aminoterephthalic acid were completely dissolved, 0.35 g of 1-butylimidazole was added and stirred to obtain a mixed solution. The mixed solution was transferred to a 1 L polytetrafluoroethylene-lined high-pressure reactor and reacted at 80 °C for 4 h and 100 °C for 10 h under a pressure of 0.8 MPa. After the reaction was completed, the mixture was naturally cooled to room temperature, washed 4 times with ethanol, and vacuum dried at 80 °C for 6 h to obtain indium-based MOF powder (the molar ratio of indium nitrate tetrahydrate: 2-aminoterephthalic acid: 1-butylimidazole was 1:1.2:0.1). (2) In-situ reduction preparation of indium-carbon composite precursor: The indium-based MOF powder obtained in step (1) was spread in a quartz boat and placed in a tube reduction furnace. Argon-hydrogen mixed gas was introduced, with Ar:H2 (volume ratio) of 95:5 and mixed gas flow rate of 30 mL / min. The temperature was first raised to 200°C at 3°C / min and held for 30 minutes. Then, the temperature was raised to 380°C at 2°C / min and held for 3 hours. The reducing atmosphere was kept circulating and the mixture was naturally cooled to room temperature to obtain a composite precursor in which indium particles are embedded in a carbon matrix. (3) Controlled etching: The composite precursor obtained in step (2) was dispersed in the etching solution at a solid-liquid ratio of 1:15 (g:mL), and placed in an ultrasonic cleaner. It was then etched for 7 hours at room temperature by intermittent ultrasonic etching (5 min ultrasonication + 2 min stop) at an ultrasonic frequency of 40 kHz. The etching solution consisted of 0.5 mol / L acetic acid and 0.1 mol / L citric acid in a volume ratio of 1:1. After etching, the product was filtered, washed, and vacuum dried to obtain porous indium powder with an oxygen content of 38 ppm, a specific surface area of ​​112.6 m² / g, a sphericity of 92.1%, and a pore size of 2.2-41 nm. Example 2

[0016] A method for preparing porous indium powder, comprising the following steps: (1) Synthesis of indium-based MOF material: 10.0 g of indium nitrate tetrahydrate and 6.0 g of 2-aminoterephthalic acid were added to 500 mL of N,N-dimethylformamide in sequence. After complete dissolution, 0.49 g of 1-butylimidazole was added and stirred to obtain a mixed solution. The mixed solution was transferred to a 1 L polytetrafluoroethylene-lined high-pressure reactor. The reaction was carried out at 80 °C for 5 h and 110 °C for 10 h under a pressure of 1.0 MPa. After the reaction was completed, the mixture was naturally cooled to room temperature, washed 4 times with ethanol, and vacuum dried at 80 °C for 6 h to obtain indium-based MOF powder (the molar ratio of indium nitrate tetrahydrate: 2-aminoterephthalic acid: 1-butylimidazole was 1:1.35:0.15). (2) In-situ reduction preparation of indium-carbon composite precursor: The indium-based MOF powder obtained in step (1) was spread in a quartz boat and placed in a tube furnace. Argon-hydrogen mixed gas was introduced, Ar:H2=85:15, and the flow rate of the mixed gas was 40mL / min. The temperature was first raised to 220°C at 5°C / min and held for 20 minutes. Then, the temperature was raised to 420°C at 3°C / min and held for 2 hours. The reducing atmosphere was kept circulating and the mixture was naturally cooled to room temperature to obtain a composite precursor in which indium particles are embedded in a carbon matrix. (3) Controlled etching: The composite precursor obtained in step (2) was dispersed in the etching solution at a solid-liquid ratio of 1:20 (g:mL), and placed in an ultrasonic cleaner. It was then etched for 8 hours at room temperature by intermittent ultrasonic etching (10 min of ultrasonic etching + 4 min of stop etching) at an ultrasonic frequency of 40 kHz. The etching solution consisted of 0.5 mol / L acetic acid and 0.1 mol / L citric acid in a volume ratio of 1:1.2. After etching, the product was filtered, washed, and vacuum dried to obtain porous indium powder with an oxygen content of 29 ppm, a specific surface area of ​​132.5 m² / g, a sphericity of 93.8%, and a pore size of 2.8-40 nm. Example 3

[0017] A method for preparing porous indium powder, comprising the following steps: (1) Synthesis of indium-based MOF material: 10.0 g of indium nitrate tetrahydrate and 6.7 g of 2-aminoterephthalic acid were added to 500 mL of N,N-dimethylformamide in sequence. After complete dissolution, 0.69 g of 1-butylimidazole was added and stirred to obtain a mixed solution. The mixed solution was transferred to a 1 L polytetrafluoroethylene-lined high-pressure reactor. The reaction was carried out at 80 °C for 6 h and 120 °C for 8 h under a pressure of 1.2 MPa. After the reaction was completed, the mixture was naturally cooled to room temperature, washed 5 times with ethanol, and vacuum dried at 80 °C for 6 h to obtain indium-based MOF powder (the molar ratio of indium nitrate tetrahydrate: 2-aminoterephthalic acid: 1-butylimidazole was 1:1.5:0.2). (2) In-situ reduction preparation of indium-carbon composite precursor: The indium-based MOF powder obtained in step (1) is spread in a quartz boat and placed in a tube reduction furnace. Argon-hydrogen mixed gas is introduced, Ar:H2=92:8, gas flow rate is 20mL / min. First, the temperature is raised to 180°C at 2°C / min and held for 40 minutes. Then, the temperature is raised to 320°C at 1°C / min and held for 4 hours. The reducing atmosphere is kept circulating and the mixture is naturally cooled to room temperature to obtain a composite precursor in which indium particles are embedded in a carbon matrix. (3) Controlled etching: The composite precursor obtained in step (2) was dispersed in the etching solution at a solid-liquid ratio of 1:5 (g:mL), and placed in an ultrasonic cleaner. It was then etched for 4 hours at room temperature by intermittent ultrasonic etching (7 min ultrasonication + 3 min stop) at an ultrasonic frequency of 40 kHz. The etching solution consisted of 0.5 mol / L acetic acid and 0.1 mol / L citric acid in a volume ratio of 1:0.8. After etching, the product was filtered, washed, and vacuum dried to obtain porous indium powder with an oxygen content of 32 ppm, a specific surface area of ​​128.5 m² / g, a sphericity of 93.2%, and a pore size of 2.5-42 nm. Example 4

[0018] A method for preparing porous indium powder, comprising the following steps: (1) Synthesis of indium-based MOF material: 10.0 g of indium nitrate tetrahydrate and 6.2 g of 2-aminoterephthalic acid were added to 500 mL of N,N-dimethylformamide in sequence. After complete dissolution, 0.42 g of 1-butylimidazole was added and stirred to obtain a mixed solution. The mixed solution was transferred to a 1 L polytetrafluoroethylene-lined high-pressure reactor. The reaction was carried out at 80 °C for 5 h and 115 °C for 10 h under a pressure of 1.0 MPa. After the reaction was completed, the mixture was naturally cooled to room temperature, washed 4 times with ethanol, and vacuum dried at 80 °C for 6 h to obtain indium-based MOF powder (the molar ratio of indium nitrate tetrahydrate: 2-aminoterephthalic acid: 1-butylimidazole was 1:1.4:0.16). (2) In-situ reduction preparation of indium-carbon composite precursor: The indium-based MOF powder obtained in step (1) was spread in a quartz boat and placed in a tube furnace. Argon-hydrogen mixed gas was introduced, Ar:H2=91:9, gas flow rate 35mL / min. The temperature was first raised to 210°C at 4°C / min and held for 30 minutes. Then, the temperature was raised to 370°C at 2°C / min and held for 3 hours. The reducing atmosphere was kept circulating and the mixture was naturally cooled to room temperature to obtain a composite precursor in which indium particles are embedded in a carbon matrix. (3) Controlled etching: The composite precursor obtained in step (2) was dispersed in the etching solution at a solid-liquid ratio of 1:12 (g:mL), and placed in an ultrasonic cleaner. It was then etched for 8 hours at room temperature using intermittent ultrasonic etching (6 min of ultrasonic etching + 2 min of stop etching) at an ultrasonic frequency of 40 kHz. The etching solution consisted of 0.5 mol / L acetic acid and 0.1 mol / L citric acid in a volume ratio of 1:1. After etching, the product was filtered, washed, and vacuum dried to obtain porous indium powder with an oxygen content of 41 ppm, a specific surface area of ​​118.5 m² / g, a sphericity of 91.9%, and a pore size of 2.0-43 nm.

Claims

1. A method for preparing porous indium powder, characterized in that, Includes the following steps: (1) Synthesis of indium-based MOF material: Indium nitrate tetrahydrate and 2-aminoterephthalic acid were added sequentially to N,N-dimethylformamide. After the indium nitrate tetrahydrate and 2-aminoterephthalic acid were completely dissolved, 1-butylimidazolium was added and stirred to obtain a mixed solution. The mixed solution was transferred to a high-pressure reactor and the pressure was maintained at 0.8~1.2MPa. The reaction was carried out at 80℃ for 4-6h and at 100-120℃ for 8-12h. After the reaction was completed, the mixture was naturally cooled to room temperature, washed with ethanol, and then vacuum dried to obtain indium-based MOF powder. (2) In-situ reduction preparation of indium-carbon composite precursor: The indium-based MOF material obtained in step (1) is placed in a reduction furnace, and a reducing gas is introduced. The temperature is first raised to 180-220°C at 2-5°C / min and held for 20-40 minutes. Then, the temperature is raised to 320-420°C at 1-3°C / min and held for 2-4 hours. The reducing atmosphere is kept circulating and the material is naturally cooled to room temperature to obtain a composite precursor in which indium particles are embedded in a carbon matrix. (3) Controllable etching: The composite precursor obtained in step (2) is dispersed in the etching solution at a solid-liquid ratio of 1 g: 5-20 mL, placed in an ultrasonic cleaner, and intermittently ultrasonically etched at room temperature for 4-8 hours. After etching, it is filtered, washed, and vacuum dried to obtain porous indium powder.

2. The method for preparing porous indium powder according to claim 1, characterized in that, In step (1), the molar ratio of indium nitrate tetrahydrate: 2-aminoterephthalic acid: 1-butylimidazole is 1:(1.2-1.5):(0.1-0.2).

3. The method for preparing porous indium powder according to claim 1, characterized in that, The reducing gas mentioned in step (2) is a mixture of hydrogen and argon, wherein the volume percentage of hydrogen is 5%-15% and the gas flow rate is 20-40 mL / min.

4. The method for preparing porous indium powder according to claim 1, characterized in that, The etching solution in step (3) is composed of 0.5 mol / L acetic acid and 0.1 mol / L citric acid in a volume ratio of 1:0.8~1.

2.

5. The method for preparing porous indium powder according to claim 1, characterized in that, The ultrasonic frequency of the intermittent ultrasonic etching in step (3) is 40kHz, and the intermittent mode is ultrasonic for 5-10 minutes and then paused for 2-4 minutes.