Preparation method of sponge platinum and prepared sponge platinum

Abstract

The invention discloses a sponge platinum preparation method and sponge platinum prepared by the same, belongs to the technical field of precious metal material preparation, and aims to solve the problems that existing sponge platinum is insufficient in purity, poor in morphology and granularity controllability, low in efficiency and insufficient in thermal stability, the purity of a raw material chloroplatinic acid is difficult to control, and safety and environmental protection are poor. The chloroplatinic acid is prepared by dissolving platinum powder and aqua regia at the temperature of 80-90 DEG C, evaporating and concentrating, refrigerating and crystallizing, and drying at the low temperature of 40-60 DEG C; the preparation method comprises the following steps: by taking chloroplatinic acid as a raw material, preparing a solution, stirring at 60-80 DEG C at 200-250r / min, adjusting the pH to 8-10 at a sodium hydroxide dropping rate of 1-3mL / min, adding formaldehyde to carry out reduction reaction, carrying out centrifugal separation at 1000-2000r / min, washing until no chloride ions exist, and drying at 100-120 DEG C for 0.5-1h to obtain the sponge platinum. Full-process parameters are optimized, the total impurity content of the prepared sponge platinum is smaller than or equal to 0.0005%, the sponge platinum is in a uniform porous spherical shape, the average particle size is 1-5 microns, the mass loss at the high temperature of 400 DEG C is smaller than or equal to 0.1%, the total reaction time is smaller than or equal to 2 h, the platinum recovery rate is larger than or equal to 99.5%, and the sponge platinum is safe and environmentally friendly and can meet the requirements of the fields of high-end electrons, precise catalysis and the like.

Description

TECHNICAL FIELD

[0001] The application belongs to the technical field of precious metal material preparation, and particularly relates to a sponge platinum preparation method and sponge platinum prepared by the method. BACKGROUND

[0002] As a kind of precious metal material with excellent catalytic performance, electrical conductivity and chemical stability, sponge platinum has irreplaceable application value in high-end electronic manufacturing, precision catalysis, aerospace and other fields. With the rapid development of the above-mentioned fields towards high precision and high reliability, more stringent requirements are put forward for the product quality of sponge platinum, especially in terms of purity, particle size and morphology, thermal stability and preparation efficiency, which directly affect the application effect in core scenarios.

[0003] The existing preparation of sponge platinum is mostly based on chloroplatinic acid as raw material, and is realized by chemical reduction method, but there are many technical defects: firstly, the product purity is insufficient, and the total impurity content is usually 0.001%-0.005% (10-50ppm), among which the existence of trace impurities such as Fe, Cu, Ag, Pb and Rh makes it difficult to meet the use requirements of high-end electronics, precision catalysis and other fields which are sensitive to impurities; secondly, the product morphology and particle size controllability are poor, and most of them are irregular block structure, which has poor dispersibility and small specific surface area, directly restricting the actual reaction efficiency in the catalytic scene; thirdly, the preparation process efficiency is low, and the total reaction time from platinum salt solution to finished product needs 6-8 hours, and the platinum recovery rate is only 95%-98%, resulting in high production cost; fourthly, the thermal stability is insufficient, and the mass loss is generally ≥0.3% under the condition of 400℃ high temperature, which shortens the service life of sponge platinum under high temperature working conditions.

[0004] As a key raw material for preparing sponge platinum, the purity and preparation process of chloroplatinic acid directly affect the final performance of sponge platinum. The existing preparation of chloroplatinic acid usually adopts the method of reacting platinum powder with aqua regia (concentrated hydrochloric acid and concentrated nitric acid mixed in a volume ratio of 3:1), but there are obvious deficiencies in the process implementation: on the one hand, the reaction temperature control is difficult, if the temperature is too high, the reaction will be too violent, which will cause the solution to splash, and if the operation is not proper in the evaporation and concentration stage, the solution may be evaporated, which will affect the product yield and purity; on the other hand, if the toxic gases such as nitrogen oxides generated in the reaction are not treated sufficiently, they will pollute the environment, and if the purity of raw materials is not controlled well or not washed thoroughly, impurities will remain in chloroplatinic acid, which will affect the preparation effect of subsequent sponge platinum. In addition, the strong corrosion and oxidation of aqua regia and the toxicity of formaldehyde and other reducing agents determine that strict safety protection measures are needed in the preparation process, but the existing technology has not formed a safety operation system matched with the optimization of process parameters, which is easy to cause safety risks due to improper operation.

[0005] In summary, the existing preparation methods of sponge platinum have obvious shortcomings in purity control, morphology and particle size regulation, preparation efficiency and thermal stability, and the preparation of the core raw material chloroplatinic acid faces the problems of great difficulty in purity control, insufficient process safety and lack of environmental protection. The inherent defects in the preparation of chloroplatinic acid will be transmitted to the preparation process of sponge platinum, and the shortcomings of the sponge platinum preparation process itself will be superimposed, resulting in that the quality of the final sponge platinum product and the comprehensive performance of the preparation process are difficult to meet the stringent demands of high-end application fields. Therefore, developing a sponge platinum preparation technology capable of realizing high purity, excellent morphology and dispersity, high efficiency, high thermal stability and safety and environmental protection has become a technical problem to be solved in the field. SUMMARY

[0006] Therefore, the purpose of the present application is to provide a sponge platinum preparation method and sponge platinum prepared thereby, so as to solve the technical problems of insufficient purity, poor controllability of morphology and particle size, low preparation efficiency and insufficient thermal stability in the existing sponge platinum preparation process, and the technical problems of great difficulty in purity control, easy residual impurities, insufficient process safety and environmental protection in the preparation process of raw material chloroplatinic acid. By optimizing the process parameters of the whole process from the synthesis of chloroplatinic acid to the preparation of sponge platinum, high-performance sponge platinum with a total impurity content of ≤0.0005%, a uniform porous spherical shape and an average particle size of 1-5 μm, a mass loss of ≤0.1% at a high temperature of 400 ℃, a total reaction time of ≤2 h and a platinum recovery rate of ≥99.5% is finally prepared.

[0007] To achieve the above-mentioned purposes, the technical solutions adopted by the present application are as follows:

[0008] The present application discloses a sponge platinum preparation method, comprising the following steps: S1, a certain amount of chloroplatinic acid is weighed and dissolved in deionized water to prepare a chloroplatinic acid solution; at the same time, a sodium hydroxide solution and a formaldehyde solution with a certain concentration are prepared; S2, the chloroplatinic acid solution prepared in step S1 is moved into a reaction container, and the reaction container is placed in a constant temperature water bath and heated to a preset temperature. Under stirring conditions, the sodium hydroxide solution is slowly added at a preset dropping rate, the pH value of the solution is adjusted to alkaline, and then the formaldehyde solution is added dropwise for reduction reaction to generate sponge platinum precipitate; S3, after the reduction reaction in step S2 is completed, the reaction liquid is cooled to room temperature, and a separation device is used to separate the sponge platinum precipitate from the reaction liquid; S4, the sponge platinum precipitate separated in step S3 is washed with deionized water for multiple times until no impurities such as chloride ions are detected in the washing liquid; after drying the washed sponge platinum precipitate, sponge platinum product is obtained.

[0009] In this invention, the method for preparing platinum sponge involves standardized solution preparation, precise control of the constant-temperature water bath reaction temperature, reagent drop rate, and pH adjustment conditions, combined with thorough washing and efficient separation processes. This not only produces a high-purity product with a total impurity content ≤0.0005% (5ppm), meeting the needs of high-end electronics, precision catalysis, and other impurity-sensitive fields, but also enables the platinum sponge to form a uniform porous spherical morphology with an average particle size controllable between 1-5μm, improving its dispersibility and specific surface area, thereby enhancing catalytic reaction efficiency. Furthermore, the total reaction time of this method is only 2 hours, far shorter than the 6-8 hours of existing technologies, and the platinum recovery rate is ≥99.5%, significantly improving preparation efficiency and raw material utilization while reducing production costs. In addition, the obtained platinum sponge exhibits a mass loss of ≤0.1% at 400℃, demonstrating stronger thermal stability and extending its service life under high-temperature conditions.

[0010] According to the method for preparing sponge platinum disclosed in this invention, in step S1, chloroplatinic acid is prepared by the following steps: S11, platinum powder is placed in a glass reaction vessel, an appropriate amount of aqua regia is added, and the mixture is heated to 80-90°C under good ventilation and continuously stirred until the platinum powder is completely dissolved; S12, after the platinum powder in step S11 is completely dissolved, the solution is further heated for evaporation and concentration to remove excess aqua regia, and the solution is prevented from drying out during the evaporation and concentration process; S13, the solution after evaporation and concentration in step S12 is cooled to room temperature and then subjected to refrigeration to allow chloroplatinic acid to crystallize out; S14, the chloroplatinic acid crystals precipitated in step S13 are collected by filtration, washed with a small amount of ice-cold deionized water, and dried at a low temperature of 40-60°C to obtain chloroplatinic acid. This chloroplatinic acid preparation process, through precise control of the dissolution temperature (80-90℃) and the degree of evaporation and concentration (avoiding the solution from drying out), combined with cold crystallization, washing with ice-cold deionized water, and low-temperature drying at 40-60℃, can effectively remove excess aqua regia and impurities on the crystal surface, significantly improving the purity of chloroplatinic acid. At the same time, it ensures the high purity of the raw materials themselves, avoiding the interference of impurities on the subsequent preparation process of sponge platinum and product quality, and providing a reliable guarantee of high-quality raw materials for obtaining high-purity, high-performance sponge platinum products.

[0011] According to the method for preparing platinum sponge disclosed in this invention, in step S2, sodium hydroxide solution is added dropwise to adjust the pH of the solution to 8-10. This alkaline range provides a suitable reaction environment for the reduction of chloroplatinic acid by formaldehyde, ensuring the smooth and efficient progress of the reduction reaction, while avoiding side reactions caused by excessively high or low pH values. This ensures the purity and morphological stability of the platinum sponge precipitate, laying the foundation for obtaining a platinum sponge product with good performance.

[0012] According to the method for preparing platinum sponge disclosed in this invention, the preset temperature in step S2 is 60-80℃. This temperature range provides suitable thermodynamic conditions for the formaldehyde reduction of chloroplatinic acid reaction, ensuring a sufficient reaction rate and guaranteeing the smooth progress of the reduction reaction. Simultaneously, it avoids premature agglomeration and abnormal morphology of the platinum sponge particles due to excessively high temperatures, effectively controls the stability of the reaction process, and reduces the risk of impurity residue caused by vigorous reactions, thereby ensuring the acquisition of a platinum sponge product with good performance and morphology.

[0013] According to the method for preparing platinum sponge disclosed in this invention, in step S2, the stirring rate is 200-250 r / min. This stirring rate can promote thorough and uniform mixing of the chloroplatinic acid solution and the sodium hydroxide solution, effectively eliminating local concentration differences during the mixing process, avoiding problems such as incomplete reduction reaction and irregular product morphology caused by uneven pH adjustment, thereby significantly improving the uniformity of the platinum sponge product and ensuring stable and controllable product performance.

[0014] According to the method for preparing platinum sponge disclosed in this invention, in step S2, the preset dropping rate of the sodium hydroxide solution is 1-3 mL / min. This slow dropping method can achieve stable adjustment of the solution pH value, avoid instability of the reaction system and violent splashing caused by sudden pH changes, prevent uneven product particle size and abnormal morphology, reduce the risk of impurity encapsulation caused by violent local reactions, create a stable and controllable environment for the subsequent formaldehyde reduction of chloroplatinic acid reaction, ensure the smooth progress of the reduction reaction, and thus guarantee the uniformity and purity of the platinum sponge product.

[0015] According to the method for preparing platinum sponge disclosed in this invention, in step S1, the concentration of sodium hydroxide solution is 1-1.5 mol / L, and the concentration of formaldehyde solution is 0.5-0.75 mol / L. This concentration ratio is optimized: the sodium hydroxide solution can efficiently adjust the pH of the reaction system to the target alkaline range, providing a suitable environment for the subsequent reduction of chloroplatinic acid by formaldehyde; the formaldehyde solution can fully exert its reducing activity, ensuring that chloroplatinic acid is directionally and efficiently reduced to platinum sponge precipitate; simultaneously, this concentration ratio avoids a decrease in process controllability due to excessively high reagent concentrations, which could lead to violent local reactions, unnecessary loss of raw materials, or the risk of impurity encapsulation, thus balancing reaction efficiency with the purity and morphological stability of the platinum sponge product.

[0016] According to the method for preparing platinum sponge disclosed in this invention, in step S3, the separation equipment is a centrifuge with a centrifugation speed of 1000-2000 r / min and a centrifugation time of 30-40 min. This combination of parameters can quickly and completely separate the platinum sponge precipitate from the reaction solution. During the separation process, it reduces the mechanical loss of the platinum sponge precipitate, lowers product loss, and significantly shortens the precipitation separation time, effectively improving the single-step separation efficiency. This lays the foundation for the smooth progress of subsequent washing and drying steps, ensuring the overall efficiency of the preparation process, and achieving a high platinum recovery rate.

[0017] According to the method for preparing platinum sponge disclosed in this invention, in step S4, the drying temperature is 100-120℃ and the drying time is 0.5-1h. These drying conditions can efficiently remove residual moisture from the platinum sponge precipitate, while also assisting in the removal of trace impurities that may remain after washing. Furthermore, they can strictly avoid the problems of platinum sponge particle agglomeration and oxidative deterioration caused by excessively high drying temperatures or excessively long drying times, ensuring that the final product maintains good physicochemical properties, high purity, and stable morphology, meeting the quality requirements of high-end applications for platinum sponge.

[0018] This invention also discloses a sponge platinum, prepared by the method disclosed herein. This sponge platinum exhibits significantly superior overall performance compared to existing technologies: Firstly, it demonstrates excellent purity: the total impurity content is ≤0.0005% (5ppm), far lower than the commonly observed 0.001%-0.005% (10-50ppm) levels in existing technologies. This can be verified by inductively coupled plasma mass spectrometry (ICP-MS) or glow discharge mass spectrometry (GD-MS), meeting the stringent requirements of high-end electronics, precision catalysis, and other fields sensitive to impurities. Secondly, it exhibits outstanding morphology and particle size advantages: Scanning electron microscopy (SEM) confirms that the sponge platinum possesses a uniform porous spherical structure with an average particle size controllable between 1-5μm, significantly higher than existing technologies. The irregular block shape of the sponge platinum results in better dispersibility and a larger specific surface area, which can effectively improve the catalytic reaction efficiency. Thirdly, it exhibits excellent thermal stability: thermogravimetric analysis (TGA) shows that the mass loss of this sponge platinum at 400℃ is ≤0.1%, superior to the existing technology's generally ≥0.3%, extending its service life under high-temperature conditions. Fourthly, it boasts both high preparation efficiency and high raw material utilization: the total reaction time from platinum salt solution to sponge platinum product is only 2 hours, significantly shorter than the existing technology's 6-8 hours, and the platinum recovery rate is ≥99.5%, higher than the conventional level of 95%-98% in existing technologies, significantly reducing production costs and improving raw material utilization.

[0019] The beneficial effects of this invention are as follows:

[0020] (1) The total impurity content of sponge platinum prepared by existing technologies is generally 0.001%-0.005% (10-50ppm), and the trace impurity residue is difficult to meet the requirements of sensitive fields such as high-end electronics and precision catalysis. The present invention uses a terminal impurity removal design of multiple washings in S4 until there are no impurities such as chloride ions, combined with precise reaction control of constant temperature water bath, stirring and controllable drop acceleration in S2, to avoid impurity encapsulation, and significantly reduce the content of trace impurities such as Fe, Cu, Ag, Pb, and Rh. The purity is significantly better than that of existing technologies and is suitable for the needs of impurity-sensitive fields such as high-end electronics and precision catalysis.

[0021] (2) Existing technologies produce platinum sponges with poor morphology and particle size controllability, often exhibiting irregular blocky structures, poor dispersibility, and small specific surface area, directly limiting catalytic reaction efficiency. This invention employs a systematic approach of temperature stabilization in an S2 constant-temperature water bath, stirring and mixing, slow dropwise addition of alkali solution, and dropwise addition of formaldehyde to precisely control the reduction reaction rate, resulting in uniform formation of platinum sponge precipitates with regular morphology and excellent dispersibility. This improves specific surface area and catalytic reaction efficiency, solving the problem of poor morphology and particle size controllability in existing technologies.

[0022] (3) Existing technologies require a total reaction time of 6-8 hours from platinum salt solution to finished sponge platinum product, and the platinum recovery rate is only 95%-98%, resulting in low production efficiency and high costs. This invention shortens the reaction cycle by utilizing the controllable reaction conditions in S2, and combines the efficient separation of the S3 separation equipment with the thorough washing in S4 to reduce platinum loss. This significantly reduces the total preparation time (only 2 hours) and significantly improves the platinum recovery rate (≥99.5%), thereby reducing precious metal waste and overall production costs.

[0023] (4) Existing platinum sponges generally suffer from a mass loss of ≥0.3% at 400℃, indicating insufficient thermal stability and limiting their use in high-temperature applications. This invention achieves this by precisely controlling the S2 reaction conditions and thoroughly removing impurities in the S4 reaction, resulting in a synergistic effect that allows the platinum sponge to form a precipitate with a complete and dense crystal structure, reducing structural defects. Simultaneously, it removes residual impurities that are prone to decomposition or volatilization at high temperatures, preventing thermal decomposition reactions caused by impurities. The final product exhibits a significantly reduced mass loss (≤0.1%) at 400℃, a greatly extended service life, and solves the problem of insufficient thermal stability in existing technologies.

[0024] (5) Existing technologies have not formed a safe operating system adapted to the optimization of process parameters, which is prone to safety hazards due to violent reactions and volatilization of toxic gases. The present invention effectively controls the reaction rate and avoids solution splashing caused by excessively violent local reactions by using a refined design of slowly adding sodium hydroxide solution at a preset dropping rate in S2, stable heating in a constant temperature water bath, and adding formaldehyde solution drop by drop. The constant temperature water bath heating replaces the unstable heating method in the existing technology, reducing the risk of reaction runaway. The stable and controllable reaction process reduces the volatilization of toxic formaldehyde gas. Combined with the subsequent standardized separation and washing steps, a safe and adapted operating procedure is formed, which solves the defects of insufficient process safety in the existing technology.

[0025] The following describes in detail the method for preparing sponge platinum of the present invention and the sponge platinum obtained therefrom, with reference to the embodiments shown in the accompanying drawings. Attached Figure Description

[0026] Figure 1 This is a flowchart illustrating the steps of the method for preparing platinum sponge according to the present invention. Detailed Implementation

[0027] To make the objectives, technical solutions, and advantages of this invention clearer, the technical solutions of this invention will be clearly and completely described below in conjunction with embodiments of this invention. Obviously, the described embodiments are one embodiment of this invention, and not all embodiments. All other embodiments obtained by those skilled in the art based on the embodiments of this invention without creative effort are within the scope of protection of this invention.

[0028] like Figure 1 As shown, this invention discloses a method for preparing platinum sponge, comprising the following steps: S1, weighing a certain amount of chloroplatinic acid and dissolving it in deionized water to prepare a chloroplatinic acid solution; simultaneously preparing a sodium hydroxide solution and a formaldehyde solution of a certain concentration; S2, transferring the chloroplatinic acid solution prepared in step S1 into a reaction vessel, placing the reaction vessel in a constant temperature water bath and heating it to a preset temperature, and under stirring conditions, slowly adding sodium hydroxide solution at a preset dropping rate, adjusting the pH of the solution to alkaline, and then adding formaldehyde solution dropwise to carry out a reduction reaction, generating platinum sponge precipitate; S3, after the reduction reaction in step S2 is completed, cooling the reaction solution to room temperature, and separating the platinum sponge precipitate from the reaction solution using a separation device; S4, washing the platinum sponge precipitate separated in step S3 multiple times with deionized water until no impurities such as chloride ions are detected in the washing solution; drying the washed platinum sponge precipitate to obtain the platinum sponge product.

[0029] Based on the above-disclosed steps, this invention, through standardized solution preparation, precise control of the constant-temperature water bath reaction temperature, reagent drop rate, and pH adjustment conditions, combined with thorough washing and efficient separation processes, can not only prepare high-purity products with a total impurity content ≤0.0005% (5ppm), meeting the needs of high-end electronics, precision catalysis, and other impurity-sensitive fields, but also enable the platinum sponge to form a uniform porous spherical morphology with an average particle size controllable at 1-5μm, improving its dispersibility and specific surface area, thereby enhancing the catalytic reaction efficiency. Simultaneously, the total reaction time of this method is only 2 hours, far shorter than the 6-8 hours of existing technologies, and the platinum recovery rate is ≥99.5%, significantly improving preparation efficiency and raw material utilization while reducing production costs. Furthermore, the obtained platinum sponge exhibits a mass loss of ≤0.1% at 400℃, demonstrating stronger thermal stability and extending its service life under high-temperature conditions.

[0030] In this embodiment of the invention, the preparation method of chloroplatinic acid in step S1 is as follows:

[0031] I. Main Reagents and Instruments

[0032] Reagents: Platinum powder, aqua regia (a mixture of concentrated hydrochloric acid and concentrated nitric acid in a volume ratio of 3:1), deionized water;

[0033] Instruments: glass reaction vessel, heating device, ventilation equipment, filtration device, etc.

[0034] II. Specific Preparation Steps

[0035] S11. Place platinum powder in a glass reaction vessel and add an appropriate amount of aqua regia. Under good ventilation, slowly heat the mixture to 80-90°C while continuously stirring until the platinum powder is completely dissolved. A large amount of toxic gas will be generated during the reaction, which must be exhausted through ventilation equipment. The reaction equation is:

[0036]

[0037] S12. After the platinum powder in step S11 has completely dissolved, continue heating the solution for evaporation and concentration to remove excess aqua regia. During the evaporation and concentration process, pay attention to controlling the temperature and degree of evaporation to avoid the solution drying out.

[0038] S13. Cool the solution after evaporation and concentration in step S12 to room temperature. Chloroplatinic acid will gradually crystallize out. To improve the crystallization effect, the solution can be refrigerated in a refrigerator for a period of time.

[0039] S14. Use a filtration device to filter and collect the chloroplatinic acid crystals precipitated in step S13. Wash the chloroplatinic acid crystals with a small amount of ice-cold deionized water to remove surface impurities, and then dry them at a low temperature of 40-60℃ to obtain the chloroplatinic acid product.

[0040] In this embodiment, the following precautions should be taken during the preparation of chloroplatinic acid: Aqua regia is highly corrosive and oxidizing, so protective glasses, gloves, and protective clothing must be worn during operation, and the process must be carried out in a fume hood to prevent toxic gases from harming human health; when heating and dissolving platinum powder, the temperature must be controlled to avoid excessively vigorous reaction that could cause the solution to splash; during the evaporation and concentration stage, close attention must be paid to changes in the solution volume to prevent the solution from drying out; high-purity platinum powder and reagents must be used to ensure the quality of the final product; toxic gases such as nitrogen oxides generated during the reaction should be appropriately treated by means of alkaline absorption to reduce environmental pollution.

[0041] In this invention, the chloroplatinic acid preparation process, through precise control of the dissolution temperature (80-90℃) and the degree of evaporation and concentration (avoiding the solution from drying out), combined with cold crystallization, washing with ice-cold deionized water, and low-temperature drying at 40-60℃, can effectively remove excess aqua regia and impurities on the crystal surface, significantly improving the purity of chloroplatinic acid. At the same time, it ensures the high purity of the raw materials themselves, avoiding the interference of impurities on the subsequent preparation process of sponge platinum and product quality, and providing a reliable guarantee of high-quality raw materials for finally obtaining high-purity, high-performance sponge platinum products.

[0042] In a preferred embodiment, in step S2, sodium hydroxide solution is added dropwise to adjust the pH of the solution to 8-10. This alkaline range provides a suitable reaction environment for the reduction of chloroplatinic acid by formaldehyde, ensuring the smooth and efficient progress of the reduction reaction, while avoiding side reactions caused by excessively high or low pH values. This, in turn, ensures the purity and morphological stability of the sponge platinum precipitate, laying the foundation for obtaining a sponge platinum product with good performance.

[0043] In a preferred embodiment, in step S2, the preset temperature is 60-80℃. This temperature range provides suitable thermodynamic conditions for the formaldehyde reduction of chloroplatinic acid reaction, ensuring a sufficient reaction rate and guaranteeing the smooth progress of the reduction reaction. Simultaneously, it avoids premature agglomeration and abnormal morphology of the sponge platinum particles due to excessively high temperatures, effectively controls the stability of the reaction process, and reduces the risk of impurity residue caused by vigorous reactions, thereby ensuring the acquisition of sponge platinum products with good performance and morphology.

[0044] In a preferred embodiment, in step S2, the stirring rate is 200-250 r / min. This stirring rate ensures that the chloroplatinic acid solution and the sodium hydroxide solution are fully and uniformly mixed, effectively eliminating local concentration differences during the mixing process. This avoids problems such as incomplete reduction reactions and irregular product morphology caused by uneven pH adjustment, thereby significantly improving the uniformity of the sponge platinum product and ensuring stable and controllable product performance.

[0045] In a preferred embodiment, in step S2, the preset dropping rate of the sodium hydroxide solution is 1-3 mL / min. This slow dropping method can achieve stable adjustment of the solution pH value, avoid instability of the reaction system and violent splashing caused by sudden pH changes, prevent uneven product particle size and abnormal morphology, reduce the risk of impurity encapsulation caused by violent local reactions, create a stable and controllable environment for the subsequent formaldehyde reduction of chloroplatinic acid reaction, ensure the smooth progress of the reduction reaction, and thus guarantee the uniformity and purity of the sponge platinum product.

[0046] In a preferred embodiment, in step S1, the concentration of the sodium hydroxide solution is 1-1.5 mol / L, and the concentration of the formaldehyde solution is 0.5-0.75 mol / L. This concentration ratio is optimized: the sodium hydroxide solution can efficiently adjust the pH of the reaction system to the target alkaline range, providing a suitable environment for the subsequent reduction of chloroplatinic acid by formaldehyde; the formaldehyde solution can fully exert its reducing activity, ensuring that chloroplatinic acid is directionally and efficiently reduced to sponge platinum precipitate; at the same time, this concentration ratio can avoid the decrease in process controllability due to excessively high reagent concentration, thereby causing localized violent reactions, unnecessary loss of raw materials, or the risk of impurity encapsulation, thus balancing reaction efficiency with the purity and morphological stability of the sponge platinum product.

[0047] In a preferred embodiment, in step S3, the separation device is a centrifuge with a centrifugation speed of 1000-2000 r / min and a centrifugation time of 30-40 min. This combination of parameters can quickly and completely separate the sponge platinum precipitate from the reaction solution. During the separation process, it can reduce the mechanical wear of the sponge platinum precipitate, reduce product loss, and significantly shorten the precipitation separation time, effectively improving the single-step separation efficiency. This lays the foundation for the smooth progress of subsequent washing and drying steps, ensuring the high efficiency of the overall preparation process, and achieving a high platinum recovery rate.

[0048] In a preferred embodiment, in step S4, the drying temperature is 100-120℃, and the drying time is 0.5-1h. These drying conditions efficiently remove residual moisture from the platinum sponge precipitate and also help remove trace impurities that may remain after washing. Furthermore, they strictly avoid problems such as agglomeration and oxidation of the platinum sponge particles caused by excessively high drying temperatures or prolonged drying times, ensuring that the final product maintains good physicochemical properties, high purity, and stable morphology, meeting the quality requirements of high-end applications for platinum sponge.

[0049] In this invention, the following precautions should be taken during the preparation of the sponge platinum: High-purity reagents should be used to avoid impurities adversely affecting product quality; the reaction temperature, solution pH, and reagent dropping rate must be strictly controlled to ensure the smooth progress of the reduction reaction and to guarantee the sponge platinum possesses good performance and morphology; since formaldehyde is a toxic and harmful gas, the operation must be carried out in a well-ventilated environment, preferably in a fume hood, and operators must wear gloves, masks, and other protective equipment; the washing process must be thorough to ensure complete removal of impurities and avoid affecting the purity and performance of the sponge platinum; the temperature during the drying stage should not be too high to prevent the sponge platinum from agglomerating or oxidizing.

[0050] This invention also discloses a sponge platinum, prepared by the sponge platinum preparation method disclosed herein. The total impurity content of the sponge platinum is ≤0.0005%, it is uniformly porous spherical with an average particle size of 1-5 μm, and the mass loss at 400℃ is ≤0.1%; the total reaction time of the preparation method is ≤2h, and the platinum recovery rate is ≥99.5%.

[0051] The multi-dimensional performance testing and advantage verification of the platinum sponge of this invention are as follows:

[0052] I. Purity Testing and Advantage Verification

[0053] The detection methods employed inductively coupled plasma mass spectrometry (ICP-MS) or glow discharge mass spectrometry (GD-MS) to focus on detecting trace impurities such as Fe, Cu, Ag, Pb, and Rh in the platinum sponge. The results showed that the total impurity content of the platinum sponge prepared by this method was ≤0.0005% (5 ppm), significantly lower than the 0.001%-0.005% (10-50 ppm) levels commonly found in existing technologies. This directly demonstrates that the product purity is significantly superior to existing technologies, meeting the stringent requirements of impurity-sensitive fields such as high-end electronics and precision catalysis.

[0054] II. Particle size and morphology detection and verification of advantages

[0055] Observation using scanning electron microscopy (SEM) revealed that the platinum sponge prepared by this method exhibits a uniform porous spherical structure (most existing technologies produce irregular blocks), and the average particle size can be precisely controlled within 1-5 μm, demonstrating superior dispersibility and a larger specific surface area, which can effectively improve the efficiency of catalytic reactions.

[0056] III. Preparation Efficiency Testing and Advantage Verification

[0057] The complete reaction cycle from platinum salt solution to finished sponge platinum was recorded. The total reaction time of this method is only 2 hours, which is significantly shorter than the 6-8 hours of the existing technology. At the same time, the test showed that the platinum recovery rate is ≥99.5%, which is higher than the conventional level of 95%-98% of the existing technology. This proves that the method has the advantages of high preparation efficiency and high raw material utilization, and can significantly reduce production costs.

[0058] IV. Stability Testing and Advantage Verification

[0059] Thermogravimetric analysis (TGA) was used to test the sponge platinum prepared by this method at a high temperature of 400℃. The mass loss was ≤0.1%, which is better than the level of ≥0.3% of the existing technology. This indicates that it has stronger thermal stability and can effectively extend its service life under high temperature conditions.

[0060] Based on the preparation method (including chloroplatinic acid preparation, sponge platinum reduction, separation, washing, and drying steps) and performance testing verification of the above embodiments, the sponge platinum prepared in this embodiment has the following significant advantages over the prior art: First, excellent purity: Detected by inductively coupled plasma mass spectrometry (ICP-MS) or glow discharge mass spectrometry (GD-MS), the total impurity content is ≤0.0005% (5ppm), far lower than the common 0.001%-0.005% (10-50ppm) level of the prior art, which can meet the stringent requirements of high-end electronics, precision catalysis, and other fields sensitive to impurities; Second, outstanding morphology and particle size advantages: Observation by scanning electron microscopy (SEM) confirmed that the sponge platinum... It exhibits a uniform porous spherical structure with an average particle size controllable between 1 and 5 μm. Compared to the irregular lumps of existing technologies, it has better dispersibility and a larger specific surface area, which can effectively improve the catalytic reaction efficiency. Thirdly, it has excellent thermal stability: through thermogravimetric analysis (TGA), the mass loss at 400℃ is ≤0.1%, which is better than the level of ≥0.3% in existing technologies, thus extending its service life under high-temperature conditions. Fourthly, it has both high preparation efficiency and high raw material utilization: the total reaction time from platinum salt solution to sponge platinum product is only 2 hours, which is significantly shortened compared to 6-8 hours in existing technologies. Moreover, the platinum recovery rate is ≥99.5%, which is higher than the conventional level of 95%-98% in existing technologies, thus significantly reducing production costs and improving raw material utilization.

[0061] It will be apparent to those skilled in the art that the present invention is not limited to the details of the exemplary embodiments described above, and that the invention can be implemented in other specific forms without departing from its spirit or essential characteristics. Therefore, the embodiments should be considered in all respects as exemplary and non-limiting, and the scope of the invention is defined by the appended claims rather than the foregoing description. Thus, all variations falling within the meaning and scope of equivalents of the claims are intended to be included within the present invention. No reference numerals in the claims should be construed as limiting the scope of the claims.

[0062] Furthermore, it should be understood that although this specification describes embodiments, not every embodiment includes only one independent technical solution. This narrative style is merely for clarity. Those skilled in the art should consider the specification as a whole, and the technical solutions in each embodiment can also be appropriately combined to form other embodiments that can be understood by those skilled in the art.

Claims

1. A method for preparing platinum sponge, characterized in that, Includes the following steps: S1, Weigh a certain amount of chloroplatinic acid and dissolve it in deionized water to prepare a chloroplatinic acid solution; at the same time, prepare a sodium hydroxide solution and a formaldehyde solution of a certain concentration respectively; S2, after transferring the chloroplatinic acid solution prepared in step S1 into the reaction vessel, the reaction vessel is placed in a constant temperature water bath and heated to the preset temperature. Under stirring conditions, the sodium hydroxide solution is slowly added dropwise at a preset dropping rate. After adjusting the pH value of the solution to alkaline, the formaldehyde solution is added dropwise to carry out the reduction reaction and generate sponge platinum precipitate. S3. After the reduction reaction in step S2 is completed, the reaction solution is cooled to room temperature, and the sponge platinum precipitate is separated from the reaction solution using a separation device. S4. Wash the sponge platinum precipitate separated in step S3 multiple times with deionized water until no impurities such as chloride ions can be detected in the washing solution; after drying the washed sponge platinum precipitate, the sponge platinum product is obtained.

2. The method for preparing platinum sponge according to claim 1, characterized in that, In step S1, the chloroplatinic acid is prepared through the following steps: S11, Platinum powder is placed in a glass reaction vessel, an appropriate amount of aqua regia is added, and the mixture is heated to 80-90°C under good ventilation and stirred continuously until the platinum powder is completely dissolved. S12. After the platinum powder in step S11 has completely dissolved, continue heating the solution for evaporation and concentration to remove excess aqua regia, and avoid drying out the solution during the evaporation and concentration process. S13, cool the solution after evaporation and concentration in step S12 to room temperature, and then refrigerate it to allow chloroplatinic acid to crystallize out. S14: The chloroplatinic acid crystals precipitated in step S13 are collected by filtration, washed with a small amount of ice-cold deionized water, and then dried at a low temperature of 40-60°C to obtain the chloroplatinic acid.

3. The method for preparing platinum sponge according to claim 2, characterized in that, In step S2, the sodium hydroxide solution is added dropwise to adjust the pH of the solution to 8-10.

4. The method for preparing platinum sponge according to claim 3, characterized in that, In step S2, the preset temperature is 60-80℃.

5. The method for preparing platinum sponge according to claim 4, characterized in that, In step S2, the stirring rate is 200-250 r / min.

6. The method for preparing platinum sponge according to claim 5, characterized in that, In step S2, the preset dropping rate of the sodium hydroxide solution is 1-3 mL / min.

7. The method for preparing platinum sponge according to claim 6, characterized in that, In step S1, the concentration of the sodium hydroxide solution is 1-1.5 mol / L, and the concentration of the formaldehyde solution is 0.5-0.75 mol / L.

8. The method for preparing platinum sponge according to claim 7, characterized in that, In step S3, the separation device is a centrifuge, and the centrifugation speed is 1000-2000 r / min, and the centrifugation time is 30-40 min.

9. The method for preparing platinum sponge according to claim 8, characterized in that, In step S4, the drying temperature is 100-120℃ and the drying time is 0.5-1h.

10. A type of platinum sponge, characterized in that, It is prepared by the method for preparing sponge platinum according to any one of claims 1-9.

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