A method for preparing high-purity silver acetate

Abstract

This invention discloses a method for preparing high-purity silver acetate. The method includes: adding an aqueous solution of ammonium acetate dropwise to an aqueous solution of silver nitrate under light-protected and stirring conditions to obtain a reaction solution; subjecting the reaction solution to low-temperature static crystallization under light-protected conditions to obtain a crystalline solution; filtering and washing the crystalline solution with ice water to obtain a solid product; and drying the solid product to obtain high-purity silver acetate. This invention uses silver nitrate and ammonium acetate as reactants, precisely controlling the reactant ratio, and combining multiple methods such as light-protected reaction throughout, low-temperature static crystallization, solid-liquid separation, ice water washing, and low-temperature light-protected drying to effectively solve the technical pain points of traditional preparation processes, such as low product purity, high impurity content, easy decomposition and yellowing of the product, and low yield. The process of this invention is simple, reproducible, and scalable. Using optimal coupled process parameters, it can stably prepare silver acetate products with a purity ≥99.5%, low impurities, high whiteness, and regular needle-like shapes.

Description

Technical Field

[0001] This invention relates to the field of fine chemical synthesis technology, specifically to a method for preparing high-purity silver acetate. Background Technology

[0002] Silver acetate is a key precious metal organic salt chemical raw material. With its excellent chemical stability, antibacterial activity, and photoelectric properties, it has become a crucial raw material in modern fine chemicals, electronics manufacturing, and new materials. In the electronics industry, silver acetate can be used to prepare conductive pastes, electronic coatings, and chip auxiliary processing materials; in organic synthesis, it can serve as a raw material for highly efficient silver catalysts; in photosensitive materials, it is a core auxiliary material for precision photosensitive films and photoelectric sensing elements; and in medical materials, it can be used to prepare high-end antibacterial dressings and antimicrobial coatings. With the rapid iteration of the electronics and information industry and the high-end new materials sector, downstream products have placed stringent requirements on the purity, impurity control precision, and appearance of silver acetate. Some high-end applications even require a purity of no less than 99.5%, with the content of various heavy metal impurities and anionic impurities controlled at the ppm or even ppb level. Simultaneously, the product must have uniform crystals, a pure white color, and no decomposition or deterioration.

[0003] Currently, the traditional silver acetate preparation process in the industry mainly uses the double decomposition precipitation method of silver nitrate and sodium acetate. This process has many inherent technical defects and cannot meet market demands: First, the reaction process of raw materials easily introduces impurities such as sodium ions, and it cannot effectively remove heavy metal impurities such as copper, bismuth, and lead. The purity of silver acetate prepared by the traditional process is only 90%-93%, and the content of heavy metal impurities is as high as 50ppm. Second, the reaction lacks low-temperature and light-protection measures, and silver acetate is extremely prone to photolysis and pyrolysis reactions, resulting in yellow or grayish-black powder with extremely poor appearance. Third, the crystallization rate at conventional room temperature is fast, and the crystals are small and loose. The product dissolution loss during filtration and washing is large, and the overall silver yield is only 75%-82%, resulting in low production cost-effectiveness. Fourth, the crystallization controllability of the traditional process is poor, and the product has irregular morphology, which cannot meet the requirements of high-end fields for needle-shaped regular crystals. Although some existing improved processes attempt to optimize the washing and drying processes, they have not specifically optimized the types and ratios of raw materials, crystallization temperature and light-shielding system. As a result, there are still problems such as incomplete removal of impurities, poor product stability (i.e., inability to form needle-shaped regular crystals) and poor repeatability, making it difficult to achieve large-scale and stable production of high-purity silver acetate.

[0004] Therefore, there is an urgent need to propose a new method for preparing high-purity silver acetate to solve the defects of existing silver acetate preparation processes, such as low product purity, high impurity content, poor appearance, low yield, and insufficient stability. Summary of the Invention

[0005] The purpose of this invention is to overcome the above-mentioned technical deficiencies and propose a method for preparing high-purity silver acetate, thereby solving the technical problems of low product purity, high impurity content, poor appearance, low yield, and insufficient stability in the existing silver acetate preparation process.

[0006] This invention provides a method for preparing high-purity silver acetate, comprising the following steps: Preparation of raw material solutions: Prepare aqueous solutions of silver nitrate and ammonium acetate; Light-protected reaction: Under light-protected and stirring conditions, an aqueous solution of ammonium acetate is added dropwise to an aqueous solution of silver nitrate to obtain a reaction solution; Low-temperature static crystallization in the dark: The reaction solution is subjected to low-temperature static crystallization under dark conditions to obtain a crystalline solution; Solid-liquid separation and ice-water washing in the dark: The crystallization liquid is filtered and washed with ice water under dark conditions to obtain a solid product; Low-temperature drying in the dark: The solid product is dried under dark conditions to obtain high-purity silver acetate.

[0007] Compared with the prior art, the beneficial effects of the present invention include: This invention uses silver nitrate and ammonium acetate as reactants. By precisely controlling the raw material ratio and combining multiple methods such as reaction in complete darkness, controlled dropping rate, low-temperature static crystallization, solid-liquid separation, ice-water washing, and low-temperature dark-shielded drying, it effectively solves the technical pain points of traditional preparation processes, such as low product purity, high impurity content, easy decomposition and yellowing of the product, and low yield. The process of this invention is simple, reproducible, and scalable. Using optimal coupled process parameters, it can stably prepare silver acetate products with a purity ≥99.5%, low impurities, high whiteness, and regular needle-like shapes. It can be widely used in high-end organic synthesis reagents, high-precision electronic chemicals, precision photosensitive materials, medical antibacterial materials, catalyst preparation, and other technical fields. It is especially suitable for high-end industrial and scientific research scenarios with extremely high requirements for raw material purity, crystal morphology, and product stability. Attached Figure Description

[0008] Figure 1 This is a photograph of the high-purity silver acetate prepared in group 11 of Example 1 of this invention; Figure 2 This is a SEM image of the high-purity silver acetate prepared in group 11 of Example 1 of this invention; Figure 3 This is a graph showing the detection results of nitrate content in the high-purity silver acetate prepared in group 11 of Example 1 of this invention. Detailed Implementation

[0009] To make the objectives, technical solutions, and advantages of this invention clearer, the invention will be further described in detail below with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are merely illustrative and not intended to limit the invention.

[0010] This invention provides a method for preparing high-purity silver acetate, comprising the following steps: S1. Preparation of raw material solutions: Prepare aqueous solutions of silver nitrate and ammonium acetate; S2, Light-protected reaction: Under light-protected and stirring conditions, ammonium acetate aqueous solution is added dropwise to silver nitrate aqueous solution to obtain the reaction solution; S3. Low-temperature static crystallization in the dark: The reaction solution is subjected to low-temperature static crystallization under dark conditions to obtain a crystalline solution; S4. Solid-liquid separation and ice-water washing in the dark: The crystallization liquid is filtered and washed with ice water under dark conditions to obtain a solid product. S5. Low-temperature drying in the dark: The solid product is dried under dark conditions to obtain high-purity silver acetate.

[0011] This invention abandons the traditional sodium acetate reaction system, using silver nitrate and ammonium acetate as reaction raw materials. It precisely controls the raw material ratio and the relative dropping rate of the ammonium acetate aqueous solution, combining multiple processes such as low-temperature static crystallization, complete light protection, solid-liquid separation and ice-water washing, and low-temperature light-protected drying. This comprehensively improves product purity and appearance by controlling impurities at the source, preventing decomposition during the process, and refining in the later stages. Specifically, ammonium acetate is used as the reaction raw material, and the reaction byproduct is ammonium nitrate, which is easily soluble in water and can be completely removed by ice-water washing, leaving no difficult-to-remove metal impurities. By limiting the specific molar ratio of silver to ammonium and using a 0-5℃ low-temperature crystallization environment, the solubility of silver acetate is significantly reduced, promoting the precipitation of needle-like dense crystals, while deeply removing metal cation and anion impurities. The low-temperature static crystallization process not only improves product yield but also directionally generates regular needle-like crystals. The complete light-protection operation completely solves the problems of photolysis discoloration and hydrolysis deterioration of silver acetate, ensuring the long-term storage stability of the product. The silver acetate product prepared using the method of this invention combined with optimal coupling process parameters can achieve a purity of over 99.5%, with the content of major metal impurities such as copper and bismuth all below 0.1 ppm, and the content of lead impurity below 5 ppm. The product is a pure white needle-like crystal with excellent appearance. Moreover, the process has excellent stability and repeatability, is easy to operate, and has controllable production costs, which can meet the needs of industrial-scale mass production. It is suitable for the use of ultra-high purity raw materials in fields such as high-end organic synthesis reagents, high-end electronics, precision antibacterial materials, and photosensitive materials. It is especially suitable for high-end industrial and scientific research scenarios with extremely high requirements for raw material purity, crystal morphology, and product stability.

[0012] In this invention, the purity of silver nitrate and ammonium acetate is analytical grade or higher, and the water is ultrapure water. This invention strictly controls the purity of the solution by selecting raw materials and water with the above-mentioned purity, thus avoiding the introduction of additional impurities.

[0013] In this invention, in step S1, the molar ratio of silver in the silver nitrate aqueous solution to ammonium in the ammonium acetate aqueous solution is 1:(1.6-1.8), preferably 1:1.7. By controlling the silver-ammonium molar ratio within the above range, this invention ensures the complete reaction of silver nitrate while avoiding excessive ammonium acetate residue that forms impurities, thus improving product purity from the source.

[0014] In this invention, in step S1, the concentration of the silver nitrate aqueous solution is 0.9-1.1 mol / L, more specifically 1 mol / L, and the concentration of the ammonium acetate aqueous solution is 1.6-1.8 mol / L, more specifically 1.7 mol / L.

[0015] In this invention, in step S2, the stirring rate is 100-300 rpm, and more specifically 200 rpm.

[0016] In this invention, in step S2, the relative dropping rate of the ammonium acetate aqueous solution is 5-20 mL / (min·mL). The relative dropping rate refers to the proportion of the volume of ammonium acetate aqueous solution added per minute to the volume of silver nitrate aqueous solution. By controlling the relative dropping rate of the ammonium acetate aqueous solution within the above range, this invention can ensure a uniform and stable dropping rate, guaranteeing the smooth progress of the metathesis reaction and avoiding excessively high local concentrations that could lead to impurity encapsulation and abnormal crystal growth.

[0017] In this invention, the dropping temperature in step S2 is room temperature.

[0018] In this invention, during step S3, the low-temperature static crystallization process is carried out at a temperature of 0-5°C for 1-2 hours. By employing this low-temperature environment, the water solubility of silver acetate can be significantly reduced, maximizing the crystallization precipitation rate and increasing product yield. Simultaneously, the low temperature slows down the crystallization rate, promoting the formation of large, uniform, and dense needle-like crystals from silver acetate, reducing the generation of fine microcrystals, decreasing product dissolution loss during subsequent filtration, and effectively inhibiting the thermal and photodecomposition side reactions of silver acetate, preventing product discoloration and impurity formation, and ensuring the product remains pure white and unspoiled.

[0019] In this invention, during step S4, the temperature of the ice water during the washing process is 0-5℃. Solid-liquid separation is performed after each wash, and in a single wash, based on the theoretical yield of silver acetate, the solid-liquid ratio is 1g:(2.5-3mL), further being 1g:3mL. By employing the above washing method, this invention can better remove nitrate and ammonium ions, as well as soluble heavy metal impurities such as copper, lead, and bismuth, adsorbed on the precipitate surface, while reducing the dissolution loss of silver acetate during the washing process, thus balancing impurity removal efficiency and product yield.

[0020] Preferably, the washing cycle is 5-6 times. By employing the above washing method and repeating the washing cycle 5-6 times, this invention effectively removes almost all impurities, leaving only a very small amount of residue, and minimizes the dissolution loss of silver acetate during the washing process. If the number of washing cycles is too low, some impurities will remain, and the product purity will not meet high-end requirements; if the number of washing cycles is too high, the impurities will not be significantly reduced, but the dissolution loss of silver acetate will increase, leading to a lower silver acetate yield.

[0021] In this invention, during step S5, the drying temperature is 50-60℃, more specifically 55℃, and the drying time is 12-15 hours, more specifically 14 hours. By controlling the drying temperature within this range, this invention can thoroughly remove residual moisture from the crystal pores while avoiding the decomposition and failure of silver acetate due to excessively high temperatures (>60℃), thus ensuring the stability of the product structure and purity.

[0022] To verify the rationality and optimization of the core process parameters and raw material selection of this invention, the following embodiments employ a single-variable control method. Gradient experiments were designed for the molar ratio of silver ammonium nitrate, the relative dropping rate of ammonium acetate aqueous solution, the static crystallization temperature, and the drying process parameters, while maintaining uniform basic process conditions (complete darkness protection, uniform stirring, 1-hour static settling, ice-water washing, and standard drying process). Simultaneously, the process parameters of Example 1 (Group 11) combined with the raw material (sodium acetate) used in the traditional process were used as Comparative Example 1. The differences in various performance indicators demonstrate the inventiveness and superiority of this invention. All embodiments and comparative examples used analytical grade silver nitrate, analytical grade ammonium acetate, analytical grade sodium acetate, and ultrapure water to prepare solutions, ensuring uniform experimental environmental conditions.

[0023] Example 1: Gradient Experiment of Molar Ratio of Silver Ammonium Raw Materials With the relative dropping rate of ammonium acetate aqueous solution fixed at 20 mL / (min·mL), the static crystallization temperature at 0-5℃, the drying temperature at 55℃, and the drying time at 14 h, the effect of the silver-ammonium molar ratio was verified by only changing the molar ratio of silver in silver nitrate to ammonium in ammonium acetate.

[0024] Group 11 A method for preparing high-purity silver acetate includes the following steps: (1) Preparation of raw material solutions: Prepare 117.74 mL of 1 mol / L silver nitrate aqueous solution and 117.68 mL of 1.7 mol / L ammonium acetate aqueous solution respectively; wherein the molar ratio of silver in silver nitrate aqueous solution to ammonium in ammonium acetate aqueous solution is 1:1.7; (2) Light-protected reaction: Under the conditions of light protection, room temperature and uniform stirring at a stirring speed of 200 rpm, ammonium acetate aqueous solution was slowly added dropwise to silver nitrate aqueous solution. The relative dropping rate of ammonium acetate aqueous solution was 20 mL / (min·mL). (3) Crystallization under light and low temperature: After the addition is complete, transfer the reaction solution to a low temperature environment of 0-5℃ and let it stand in the dark for 1 hour; (4) Light-protected filtration and ice water washing: After the crystallization is completed at low temperature, vacuum filtration is carried out under light-protected conditions to separate the crude precipitate of silver acetate; ice water (ultrapure water) pre-cooled at 0-5℃ is used to wash the precipitate in 6 small batches, and the precipitate is thoroughly stirred and moistened in each wash before filtration; in the process of each wash, the solid-liquid ratio is 1g:3mL based on the theoretical yield of silver acetate. (5) Low temperature and light-proof drying: Spread the washed pure silver acetate precipitate evenly on the drying tray, place it in the light-proof constant temperature drying oven, set the drying temperature to 55℃, and dry at a constant temperature for 14h.

[0025] Group 12 Compared with group 11 in Example 1, the only difference is that the silver-ammonium molar ratio is fixed at 1:1.2, and step (1) is as follows: (1) Preparation of raw material solutions: Prepare 117.74 mL of 1 mol / L silver nitrate aqueous solution and 117.63 mL of 1.2 mol / L ammonium acetate aqueous solution respectively.

[0026] Group 13 Compared with group 11 in Example 1, the only difference is that the silver-ammonium molar ratio is fixed at 1:1.5, and step (1) is as follows: (1) Preparation of raw material solutions: Prepare 117.74 mL of silver nitrate aqueous solution with a concentration of 1 mol / L and 117.71 mL of ammonium acetate aqueous solution with a concentration of 1.5 mol / L respectively.

[0027] Group 14 Compared with group 11 in Example 1, the only difference is that the silver-ammonium molar ratio is fixed at 1:2.0, and step (1) is as follows: (1) Preparation of raw material solutions: Prepare 117.74 mL of silver nitrate aqueous solution with a concentration of 1 mol / L and 117.67 mL of ammonium acetate aqueous solution with a concentration of 2.0 mol / L respectively.

[0028] Example 2: Relative Dropping Acceleration Gradient Experiment of Ammonium Acetate Aqueous Solution With the silver-ammonia molar ratio fixed at 1:1.7, the static crystallization temperature at 0-5℃, the drying temperature at 55℃, and the drying time at 14h, the effect of the relative dropping rate was verified by only changing the relative dropping rate of the ammonium acetate aqueous solution.

[0029] Group 21 Compared with group 11 in Example 1, the only difference is that the relative dropping rate of the ammonium acetate aqueous solution is 5 mL / (min·mL).

[0030] Group 22 Compared with group 11 in Example 1, the only difference is that the relative dropping rate of the ammonium acetate aqueous solution is 35 mL / (min·mL).

[0031] Group 23 The only difference from group 11 in Example 1 is that the relative dropping rate of the ammonium acetate aqueous solution is 50 mL / (min·mL).

[0032] Example 3: Temperature gradient experiment for static crystallization With the silver-ammonia molar ratio fixed at 1:1.7, the relative dropping rate of the ammonium acetate aqueous solution at 20 mL / (min·mL), the drying temperature at 55℃, and the drying time at 14 h, the effect of the static crystallization temperature was verified by only changing the static crystallization temperature.

[0033] Group 31 Compared with group 11 in Example 1, the only difference is that the static crystallization temperature is room temperature (generally 25°C).

[0034] Group 32 Compared with group 11 in Example 1, the only difference is that the static crystallization temperature is 10-15℃.

[0035] Group 33 Compared with group 11 in Example 1, the only difference is that the static crystallization temperature is -5 to 0°C.

[0036] Example 4: Gradient Experiment of Drying Process Parameters With a fixed silver-ammonia molar ratio of 1:1.7, a relative dropping rate of 20 mL / (min·mL) for ammonium acetate aqueous solution, and a static crystallization temperature of 0-5℃, the effects of drying process parameters were verified by only changing the drying temperature and drying time.

[0037] Group 41 Compared with group 11 in Example 1, the only difference is that the drying temperature is 45°C and the drying time is 12h.

[0038] Group 42 Compared with group 11 in Example 1, the only difference is that the drying temperature is 65°C and the drying time is 14h.

[0039] Group 43 Compared with group 11 in Example 1, the only difference is that the drying temperature is 75°C and the drying time is 10h.

[0040] Comparative Example 1 Compared with group 11 in Example 1, the only difference is that sodium acetate, a raw material commonly used in the industry, is used instead of ammonium acetate. A comparative sample is prepared based on the metathesis reaction of silver nitrate and sodium acetate for performance differentiation comparison; wherein, step (1) is as follows: (1) Preparation of raw material solutions: Prepare 117.74 mL of 1 mol / L silver nitrate aqueous solution and 117.68 mL of 1.7 mol / L sodium acetate aqueous solution respectively; wherein the molar ratio of silver in silver nitrate aqueous solution to sodium in sodium acetate aqueous solution is 1:1.7.

[0041] Performance testing Performance tests were conducted on the above embodiments and comparative examples, and the test results are shown in Tables 1-6.

[0042] Table 1

[0043] Please refer to Table 1. As can be seen from Table 1, when the traditional sodium acetate metathesis reaction is carried out using the relevant parameters of group 11 in Example 1, the raw material residue is large, the product purity and yield are low, the crystals are fine and fragmented, and the color is dark and yellow. Using ammonium acetate will have a significantly better effect.

[0044] Table 2

[0045] Please refer to Table 2. As can be seen from Table 2, when the silver-ammonium molar ratio in Group 12 is 1:1.2, the reaction is incomplete, the amount of raw material residue is large, the product purity and yield are low, and the crystals are small and loose. When the silver-ammonium molar ratio in Group 13 is 1:1.5, the reaction is basically complete, the product purity and yield are improved, and a small amount of crystals are fine and broken. When the silver-ammonium molar ratio in Group 11 is 1:1.7, the reaction is complete with no residue, the product purity and silver yield are high, the impurities are low, and the needle-like crystals are regular and dense. When the silver-ammonium molar ratio in Group 14 is 1:2.0, there is an excess of ammonium acetate residue. The large amount of soluble ammonium salt residue in the system easily adsorbs impurities and encapsulates crystals, resulting in impurity enrichment, crystal defects, and a slightly dark overall color of the product with trace amounts of impurity crystals.

[0046] Table 3

[0047] Please refer to Table 3. As can be seen from Table 3, in Group 21, when the relative dropping rate is 5 mL / (min·mL), the dropping rate is too slow. Although the performance is improved, it will lead to a longer reaction cycle. In Group 11, when the relative dropping rate is 20 mL / (min·mL), the impurities are basically completely removed, with only a very small amount of impurities remaining. The crystals grow gradually, and the crystal form is dense and complete. In Group 22, when the relative dropping rate is 35 mL / (min·mL), short-term concentration fluctuations will cause trace impurities to be encapsulated, which can generate a small number of needle-like crystals, but the overall regularity is insufficient, and there are still fine powder inclusions. In Group 23, when the relative dropping rate is 50 mL / (min·mL), the concentration of reactants in the local reaction system is instantly overloaded, and the metathesis reaction bursts violently in an instant. A large number of fine silver acetate crystals precipitate rapidly, which easily encapsulate trace heavy metal impurities and anion residues in the solution. The crystals are loose, porous, and have many defects.

[0048] Table 4

[0049] Please refer to Table 4. As can be seen from Table 4, in Group 31, the static crystallization temperature is room temperature, the crystallization speed is fast, a large number of microcrystals are generated, the product purity and yield are low, impurities are severely enriched, and the product is yellowish; in Group 32, when the static crystallization temperature is 10-15℃, the product purity and yield are improved, but the crystallization stability is average and the crystal regularity is poor; in Group 11, when the static crystallization temperature is 0-5℃, the crystallization is slow, which can effectively remove impurities, and the product purity and yield are significantly increased. The product is pure white needle-shaped crystals that are regular and dense; in Group 33, when the static crystallization temperature is -5-0℃, the solution is prone to freezing, resulting in uneven crystallization, poor process controllability, a significant decrease in silver yield, and local agglomeration of the product.

[0050] Table 5

[0051] Please refer to Table 5. As can be seen from Table 5, in Group 41, the lower drying temperature and time resulted in incomplete moisture removal, high product moisture content, susceptibility to moisture absorption and deterioration, and lower product purity. In Group 11, a suitable drying temperature was used, resulting in complete moisture removal, no decomposition or deterioration, and excellent product stability. In Group 42, a higher drying temperature was used, causing slight thermal decomposition of silver acetate, a slightly yellowish product, trace amounts of oxidation impurities, and a slight decrease in product purity. In Group 43, an excessively high drying temperature was used, causing extensive decomposition of silver acetate, resulting in a blackened product and a significant decrease in product purity.

[0052] Please also see Figure 1-3 ,pass Figure 1-2It can be seen that the high-purity silver acetate prepared in group 11 of Example 1 of this invention is a pure white needle-like crystal, and is regular and dense; the nitrate content was detected by the sodium indigo disulfonate colorimetric method as a limit control test, and the concentration of the nitrate standard solution used was 5 μg / mL. Figure 3 As can be seen, there is no significant difference in color between the control and the control, indicating that the nitrate content is at the ppm level.

[0053] The above results show that the optimal coupled process parameters defined in this invention are: a silver-ammonia molar ratio of 1:1.7, a relative dropping rate of 5-20 mL / (min·mL) for the ammonium acetate aqueous solution, low-temperature crystallization at 0-5℃, and low-temperature drying in the dark at 50-60℃. The silver acetate product prepared based on these parameters has a purity ≥99.5%, low impurities, high whiteness, and a regular needle-like structure. This effectively solves the technical pain points of traditional preparation processes, such as low product purity, high impurity content, easy decomposition and yellowing of the product, and low yield. When the parameters deviate from the scope of protection of this invention, problems such as decreased product purity, increased impurities, decreased yield, deteriorated appearance, and insufficient stability occur. This fully demonstrates that the process parameters of this invention cannot be obtained from conventional limited experiments, possessing significant innovation and inventiveness. Furthermore, the process adaptability, repeatability, and scalability are superior to existing technologies.

[0054] In summary, the present invention has the following significant advantages: (1) Ultra-high purity and low impurities: This invention uses ammonium acetate to replace traditional sodium acetate raw material, avoiding sodium ion impurity residue. Combined with low temperature crystallization and ice water washing process, heavy metals and anionic impurities are deeply removed. The product purity can reach up to 99.96%, and the content of various core impurities is far lower than the industry standard, which fully meets the stringent requirements of high-end electronics and precision chemicals.

[0055] (2) Excellent product quality and strong stability: The whole process of light protection process completely suppresses the side reactions of silver acetate photolysis and hydrolysis. Low temperature and slow crystallization form dense and regular needle-shaped pure white crystals, which solves the problems of yellowing, blackening and loose powder of traditional products, and greatly improves the storage stability of the product.

[0056] (3) Significantly improved yield: The low temperature environment reduces the solubility of silver acetate, reduces dissolution loss, and the dense crystal particles reduce product loss during filtration and washing. The total silver yield increases from the traditional 75%-82% to 88%-94%, greatly improving the utilization rate of raw materials and reducing production costs.

[0057] (4) Controllable process and adaptable to large-scale production: The process parameters of this invention are accurate, the operation is simple and the repeatability is good. All processes can be standardized and automated. There are no complex equipment or harsh reaction conditions. It can be directly applied to large-scale industrial production and has extremely high industrialization value.

[0058] (5) Wide applicability of the product: The regular needle-like crystal morphology, ultra-high purity and stability make the product of this invention suitable for high-end application scenarios in many fields such as high-end conductive materials, precision photosensitive elements, medical antibacterial materials, and high-end catalytic synthesis.

[0059] The specific embodiments of the present invention described above do not constitute a limitation on the scope of protection of the present invention. Any other corresponding changes and modifications made in accordance with the technical concept of the present invention should be included within the scope of protection of the claims of the present invention.

Claims

1. A method for preparing high-purity silver acetate, characterized in that, Includes the following steps: Preparation of raw material solutions: Prepare aqueous solutions of silver nitrate and ammonium acetate; Light-protected reaction: Under light-protected and stirring conditions, the ammonium acetate aqueous solution is added dropwise to the silver nitrate aqueous solution to obtain a reaction solution; Low-temperature static crystallization in the dark: The reaction solution is subjected to low-temperature static crystallization under dark conditions to obtain a crystalline solution; Solid-liquid separation and ice-water washing in the dark: The crystallized liquid is filtered and washed with ice water under dark conditions to obtain a solid product; Low-temperature drying in the dark: The solid product is dried under dark conditions to obtain high-purity silver acetate.

2. The method for preparing high-purity silver acetate according to claim 1, characterized in that, The purity of silver nitrate and silver acetate is analytical grade or higher, and the water is ultrapure water.

3. The method for preparing high-purity silver acetate according to claim 1, characterized in that, The molar ratio of silver in the silver nitrate aqueous solution to ammonium in the ammonium acetate aqueous solution is 1:(1.6-1.8); and / or, The molar ratio of silver in the silver nitrate aqueous solution to ammonium in the ammonium acetate aqueous solution is 1:1.

7.

4. The method for preparing high-purity silver acetate according to claim 1, characterized in that, The concentration of the silver nitrate aqueous solution is 0.9-1.1 mol / L, and the concentration of the ammonium acetate aqueous solution is 1.6-1.8 mol / L.

5. The method for preparing high-purity silver acetate according to claim 1, characterized in that, During the stirring process, the stirring speed is 100-300 rpm.

6. The method for preparing high-purity silver acetate according to claim 1, characterized in that, During the process of adding the ammonium acetate aqueous solution dropwise to the silver nitrate aqueous solution, the relative dropping rate of the ammonium acetate aqueous solution is 5-20 mL / (min·mL).

7. The method for preparing high-purity silver acetate according to claim 1, characterized in that, During the process of adding the ammonium acetate aqueous solution dropwise to the silver nitrate aqueous solution, the dropwise temperature is room temperature.

8. The method for preparing high-purity silver acetate according to claim 1, characterized in that, During the low-temperature static crystallization process, the temperature is 0-5℃ and the time is 1-2 hours.

9. The method for preparing high-purity silver acetate according to claim 1, characterized in that, During the ice water washing process, the temperature of the ice water is 0-5℃. Solid-liquid separation is performed after each wash, and the number of washes is 5-6. In a single wash, based on the theoretical yield of silver acetate, the solid-liquid ratio is 1g:(2.5-3)mL.

10. The method for preparing high-purity silver acetate according to claim 1, characterized in that, The drying temperature is 50-60℃, and the drying time is 12-15 hours; and / or, The drying temperature is 55℃, and the drying time is 14 hours.

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