Method for preparing antimony phosphate by directly adopting elemental antimony
By reacting elemental antimony with concentrated sulfuric acid to generate ionic antimony, which is then reacted with sodium dihydrogen phosphate dihydrate, the problem of long synthesis time and high equipment requirements in traditional antimony phosphate synthesis is solved, and efficient and simple high-purity antimony phosphate preparation is achieved.
Patent Information
- Application Number
- CN202511260972.9
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2025-09-05
- Publication Date
- 2025-11-21
AI Technical Summary
Traditional methods for synthesizing antimony phosphate are time-consuming, require sophisticated equipment, and their purity depends on the purity of the raw materials, making it difficult to control impurities and thus hindering the efficient preparation of high-purity antimony phosphate.
The synthesis method involves reacting elemental antimony with concentrated sulfuric acid to generate ionic antimony, which is then reacted with sodium dihydrogen phosphate dihydrate to generate antimony phosphate. This avoids high-temperature processing and achieves rapid and efficient synthesis by controlling temperature and moisture content.
The synthesis method is simple, requires low equipment, is short-time, and the product purity is as high as 99%, with a yield of 95%, breaking through the conventional understanding that elemental antimony is difficult to directly prepare antimony phosphate.
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Figure CN120987284A_ABST
Abstract
Description
TECHNICAL FIELD
[0001] The present application relates to a method for preparing antimony phosphate directly using elemental antimony, and belongs to the field of chemical synthesis. BACKGROUND
[0002] Antimony phosphate is an inorganic compound, and its chemical formula is generally represented as SbPO4. It is a white solid composed of antimony (Sb), phosphorus (P), and oxygen (O) elements. The traditional synthesis method of antimony phosphate is to stir Sb2O3 solid with H3PO4 solution at room temperature for 1 month, wash with cold water after filtration, and finally dry at 120℃, and then heat at 800℃ for 8 hours to obtain antimony phosphate single crystal suitable for X-ray diffraction analysis. However, this process takes a long time, needs to be stirred for 1 month, and the equipment requirements are high for 800℃ high temperature treatment. The product purity depends on the purity of raw materials, and the impurity control is difficult.
[0003] In view of the above problems, the present application provides a method for preparing antimony phosphate directly using elemental antimony. The synthesis method is easy to operate, has low requirements on synthesis equipment, does not require high temperature reaction, and has short time consumption, high efficiency, and high product purity. SUMMARY
[0004] The purpose of the present application is to provide a method for preparing antimony phosphate directly using elemental antimony. In the present application, antimony powder is dissolved in concentrated sulfuric acid, and the dissolved ionic antimony element can immediately generate antimony phosphate when it meets phosphate. The synthesis method is easy to operate, does not require high temperature reaction, has short time consumption, high efficiency, and high product purity.
[0005] The technical solution of the present application is a method for preparing antimony phosphate directly using elemental antimony, which is carried out according to the following steps: (1) Add antimony powder to concentrated sulfuric acid, mix and heat to 140-160℃, and continuously heat for 5-25min. The mass ratio of antimony powder to concentrated sulfuric acid is 1:12-22. After the antimony powder is completely dissolved, cool to 60-80℃ to obtain an antimony sulfate solution, which is ready for use; (2) Heat solid sodium dihydrogen phosphate dihydrate to 60℃ higher than its melting point to obtain sodium dihydrogen phosphate dihydrate liquid, which is ready for use; (3) Add the sodium dihydrogen phosphate dihydrate liquid of step (2) to the antimony sulfate solution of step (1), and stir. The molar ratio of sodium dihydrogen phosphate dihydrate liquid to antimony powder is 1.3-1.7:1. After stirring, filter and discard the filtrate. Collect the precipitate, wash until the pH is greater than 6, and then dry to obtain antimony phosphate powder.
[0006] In the aforementioned step (1), the antimony powder is added to concentrated sulfuric acid, mixed and heated to 150℃, and continuously heated for 10-20min.
[0007] In the aforementioned step (1), the mass ratio of antimony powder and concentrated sulfuric acid is 1:21.
[0008] In the aforementioned step (3), the stirring time is 8-12 min.
[0009] Specifically, in the aforementioned step (3), the stirring time is 10 min.
[0010] In the aforementioned step (3), the molar ratio of sodium dihydrogen phosphate dihydrate liquid to antimony powder is 1.5:1.
[0011] In the aforementioned step (3), the drying temperature is 105-115℃, and the drying time is 1 h.
[0012] Specifically, in the aforementioned step (3), the drying temperature is 110℃, and the drying time is 0.8-1.2 h.
[0013] Advantages of the present application 1. The synthesis method is easy to operate, has low requirements on the synthesis equipment, does not require high-temperature reaction, is time-saving, efficient, and has high product purity (up to 99%) and product yield (up to 95%).
[0014] 2. The method directly uses elemental antimony as the raw material, and all raw materials are common inorganic substances, which are easy to obtain. The product can be obtained through inorganic synthesis reaction, which shortens the synthesis route, simplifies the complex problem, and reduces the cost.
[0015] 3. The present application breaks through the conventional understanding that elemental antimony and phosphoric acid are difficult to react and cannot be used as direct raw materials to prepare antimony phosphate. Through innovative experiments, the reagent-sulfuric acid is selected as the medium. The elemental antimony is converted into ionic antimony through acidification of sulfuric acid, and then reacts with phosphate to generate antimony phosphate precipitate. The product and raw material are separated through filtration to obtain high-purity antimony phosphate product.
[0016] 4. In order to avoid the problem that the intermediate product antimony sulfate is unstable in nature and will hydrolyze into insoluble by-products when water is encountered, the present application uses solid sodium dihydrogen phosphate with little water as the reagent to provide phosphate, avoids the introduction of too much water, and controls the appropriate temperature conditions to effectively prevent hydrolysis. BRIEF DESCRIPTION OF DRAWINGS
[0017] Figure 1 : XRD pattern of antimony phosphate product prepared by five schemes; Figure 2 : XRD pattern of antimony phosphate product prepared by scheme four. DETAILED DESCRIPTION
[0018] The present application will be further described below in conjunction with examples, but it is not used as the basis for limiting the present application.
[0019] Example 1: Preparation method of antimony phosphate (1) Antimony powder was added into concentrated sulfuric acid, and mixed and heated to 150°C, and heated for 15 min, the mass ratio of the antimony powder and the concentrated sulfuric acid was 1:21, after the antimony powder was completely dissolved, it was cooled to 60-80°C to obtain an antimony sulfate solution, which was prepared for use; (2) The solid sodium dihydrogen phosphate dihydrate was heated to 60°C higher than its melting point to obtain a sodium dihydrogen phosphate dihydrate liquid, which was prepared for use; (3) The sodium dihydrogen phosphate dihydrate liquid of step (2) was added into the antimony sulfate solution of step (1), and stirred for 10 min, the molar ratio of the sodium dihydrogen phosphate dihydrate liquid and the antimony powder was 1.5:1, after stirring, it was filtered, the filtrate was discarded, and the precipitate was collected, washed until the pH was greater than 6, and then dried at 110°C for 1 h to obtain antimony phosphate powder.
[0020] Example 2: Preparation method of antimony phosphate (1) Antimony powder was added into concentrated sulfuric acid, and mixed and heated to 140°C, and heated for 25 min, the mass ratio of the antimony powder and the concentrated sulfuric acid was 1:22, after the antimony powder was completely dissolved, it was cooled to 60-80°C to obtain an antimony sulfate solution, which was prepared for use; (2) The solid sodium dihydrogen phosphate dihydrate was heated to 60°C higher than its melting point to obtain a sodium dihydrogen phosphate dihydrate liquid, which was prepared for use; (3) The sodium dihydrogen phosphate dihydrate liquid of step (2) was added into the antimony sulfate solution of step (1), and stirred for 8 min, the molar ratio of the sodium dihydrogen phosphate dihydrate liquid and the antimony powder was 1.3:1, after stirring, it was filtered, the filtrate was discarded, and the precipitate was collected, washed until the pH was greater than 6, and then dried at 105°C for 1.2 h to obtain antimony phosphate powder.
[0021] Example 3: Preparation method of antimony phosphate (1) Antimony powder was added into concentrated sulfuric acid, and mixed and heated to 160°C, and heated for 5 min, the mass ratio of the antimony powder and the concentrated sulfuric acid was 1:12, after the antimony powder was completely dissolved, it was cooled to 60-80°C to obtain an antimony sulfate solution, which was prepared for use; (2) The solid sodium dihydrogen phosphate dihydrate was heated to 60°C higher than its melting point to obtain a sodium dihydrogen phosphate dihydrate liquid, which was prepared for use; (3) The sodium dihydrogen phosphate dihydrate liquid of step (2) was added into the antimony sulfate solution of step (1), and stirred for 12 min, the molar ratio of the sodium dihydrogen phosphate dihydrate liquid and the antimony powder was 1.7:1, after stirring, it was filtered, the filtrate was discarded, and the precipitate was collected, washed until the pH was greater than 6, and then dried at 115°C for 0.8 h to obtain antimony phosphate powder.
[0022] A large number of experimental researches were carried out to prove the effect of the present application, and the following are the results of the experimental researches of the present application: 1. Screening of antimony phosphate preparation schemes 1.1 Reaction of antimony powder with 70% phosphoric acid 1.1.1 Preparation of 70% phosphoric acid: 60 g of phosphoric acid was taken and 12.86 g of water was added to prepare it.
[0023] 1.1.2 Synthesis reaction: 5 g of antimony powder was taken and 14.49 g of 70% phosphoric acid was added to a beaker, which was heated in a water bath at 80°C for 2 hours.
[0024] Observation: white mist and bubbles were generated, and a large amount of unreacted antimony was present. The reaction product was filtered, and the filter residue was dried in an oven at 120°C. The results are shown in Table 1, and the filter residue weighed 8.68 g.
[0025] Table 1: Filter residue mass after drying in an oven for different times Conclusion: the filter residue after the reaction of antimony and phosphoric acid was 8.68 g, the original antimony powder was 5 g, and a large amount of antimony was unreacted, indicating that it contained unreacted antimony and reaction products; the crystalline mass precipitated after the reaction of the filtrate and sodium hydroxide was too small to be weighed, and this experiment can exclude the scheme of preparing antimony phosphate by reacting antimony powder with phosphoric acid.
[0026] 1.2 Investigation of antimony sulfate precipitate generated by the reaction of antimony powder with sulfuric acid Preparation of antimony sulfate precipitate: 1 g of antimony powder was added to 21 g of concentrated sulfuric acid, and the mixture was heated to 150°C for 10-20 min. After the antimony powder was completely dissolved, the mixture was cooled to 60-80°C, and the antimony sulfate solid was obtained by filtration.
[0027] The antimony sulfate precipitate was taken and its properties under different conditions were investigated as follows: (1) Heating of the antimony sulfate precipitate: after heating the precipitate to more than 110°C, the precipitate dissolved into a solution, and after cooling, it crystallized again (initially all crystalline, and after a period of time, part of the crystals changed into white substances).
[0028] (2) Solubility of the antimony sulfate precipitate in water: the antimony sulfate precipitate was added to water, and it was found that the antimony sulfate precipitate was not soluble in water, even after heating; (3) Solubility of the antimony sulfate precipitate under acidic conditions: water was added to the antimony sulfate precipitate and stirred, and on this basis, concentrated sulfuric acid was added, and the precipitate dissolved.
[0029] 1.3 Investigation of the solubility of the antimony sulfate precipitate in different acids The antimony sulfate prepared in item 1.2 was taken and added to different acids to investigate its solubility, so as to understand the properties of the intermediate product antimony phosphate and facilitate the control of its formation. The results are as follows: (1) 0.2 g of antimony sulfate precipitate + 3.67 g of concentrated sulfuric acid: the result is that the antimony sulfate precipitate is dissolved in concentrated sulfuric acid when heated to 90°C; (2) 0.2 g of antimony sulfate precipitate + 10.05 g of concentrated phosphoric acid: the result is that the antimony sulfate precipitate is not dissolved in concentrated phosphoric acid, and is not dissolved even when heated; (3) 0.2 g of antimony sulfate precipitate + 3.13 g of 37% hydrochloric acid: the result is that the antimony sulfate precipitate can be dissolved in 37% hydrochloric acid at room temperature; (4) 0.2 g of antimony sulfate precipitate + 10.85 g of nitric acid: the result is that the antimony sulfate precipitate is not dissolved in nitric acid, and is not dissolved even when heated.
[0030] Conclusion: The antimony sulfate precipitate is dissolved in concentrated sulfuric acid when heated to 90°C, and the raw material for preparing the antimony sulfate precipitate is also concentrated sulfuric acid. It can be considered to directly maintain a certain temperature during the preparation of antimony sulfate, so that the antimony sulfate is in a liquid state, which is convenient for the subsequent preparation of antimony phosphate, and other acids do not need to be added.
[0031] 1.4 Relationship between the amount of antimony powder and concentrated sulfuric acid: 0.42 g of antimony powder was continuously added to the solution of 1 g of antimony powder + 25 g of concentrated sulfuric acid, and white precipitate was precipitated, and the antimony powder was completely dissolved, and then 5.04 g of concentrated sulfuric acid was added to dissolve the precipitate.
[0032] Antimony powder: concentrated sulfuric acid = 1.42:30.04 = 1:21.1549.
[0033] 1 g of antimony powder + 25 g of concentrated sulfuric acid (covered with a watch glass), and then 1.26 g of antimony powder was continuously added in multiple times, and a large amount of precipitate was precipitated, and the antimony powder was completely dissolved, and then distilled water was added after cooling, stirred, and a white turbid liquid was obtained. After filtration and washing, 5.83 g of product was obtained after drying at 100°C for 1 h. (Total 2.26 g of antimony powder) Antimony powder: concentrated sulfuric acid = 2.26:25 = 1:11.06.
[0034] 1.86 g of antimony powder + 25 g of concentrated sulfuric acid (covered with a watch glass), and then 0.98 g of antimony powder was continuously added in multiple times, and a large amount of precipitate was precipitated, and the antimony powder was completely dissolved, and then the precipitate was directly stored in a sample bag without any treatment after cooling. (Total 2.84 g of antimony powder) Antimony powder: concentrated sulfuric acid = 2.84:25 = 1:8.8.
[0035] Conclusion: The ratio of concentrated sulfuric acid to antimony powder is greater than or equal to 11.06, and the antimony powder can be completely dissolved under heating to form a transparent solution.
[0036] 1.5. Preparation of phosphoric acid gradient process for antimony sulfate Sb2(S04)3 precipitate was first taken, and after dissolution under acidic conditions, sodium dihydrogen phosphate solution, distilled water, sodium hydroxide solution, and / or sodium hydroxide solution was added directly to the Sb2(S04)3 precipitate, and the obtained products were analyzed. The specific experiments are as follows: (1) 0.5 g of Sb2(S04)3 precipitate + 2.75 g of 37% hydrochloric acid + 1.22 g of sodium dihydrogen phosphate (solution), white flocculent precipitate was generated and dissolved, 1.2 g of sodium dihydrogen phosphate (solution) was continuously added, white precipitate was generated, and 0.53 g of product was obtained after filtration, washing, and drying at 100°C for 1 h.
[0037] (2) Sb2(S04)3 precipitate + 37% hydrochloric acid + distilled water dilution: white precipitate was generated, and the precipitate was Sb2(S04)3 hydrolyzate.
[0038] (3) Sb2(S04)3 precipitate + 37% hydrochloric acid + 1 mol / L sodium hydroxide solution: white precipitate was generated, and the precipitate was Sb2(S04)3 hydrolyzate.
[0039] (4) 0.5 g of Sb2(S04)3 precipitate + 7.38 g of 37% hydrochloric acid + 0.5 g of solid sodium dihydrogen phosphate, stirring and dissolving, white precipitate was generated, and the precipitate was antimony phosphate. Then sodium hydroxide was added, and during the process of adding sodium hydroxide solution, no obvious change in the precipitate was observed. When 3.01 g of 1 mol / L sodium hydroxide solution was added, the generated white precipitate dissolved, indicating that antimony phosphate was soluble in caustic soda.
[0040] Directly using 0.1 g of Sb2(S04)3 precipitate + 3.50 g of 1 mol / L sodium hydroxide solution: the Sb2(S04)3 precipitate cannot be directly dissolved in the sodium hydroxide solution, and heating does not dissolve it. This indicates that Sb2(S04)3 is insoluble in caustic soda.
[0041] (6) 0.5 g of Sb2(S04)3 precipitate + 3.67 g of concentrated sulfuric acid + 0.5 g of dihydrogen phosphate sodium dihydrate liquid (the liquid is obtained by heating solid dihydrogen phosphate sodium dihydrate to a temperature higher than its melting point by 60°C), stirring and dissolving, white precipitate was generated, and during the process of adding sodium hydroxide solution, no obvious change in the precipitate was observed. When 3.01 g of 1 mol / L sodium hydroxide solution was added, the generated white precipitate dissolved. This indicates that antimony phosphate is soluble in caustic soda.
[0042] Conclusion: The above experiments found that Sb2(S04)3 is easily hydrolyzed and precipitates as insoluble basic salt. Therefore, in this scheme, Sb2(S04)3 precipitate is reacted with dihydrogen phosphate sodium dihydrate liquid (the liquid is obtained by heating solid dihydrogen phosphate sodium dihydrate to a temperature higher than its melting point by 60°C) in concentrated sulfuric acid to generate antimony phosphate, and the conversion rate or yield reaches 95%.
[0043] 1.6 Optimal process experiment According to the above experimental findings, antimony powder can be dissolved in a certain amount of sulfuric acid, the mass ratio of antimony powder to sulfuric acid must be greater than 1:12, that is, the mass of sulfuric acid is 12 times the mass of antimony powder. Under this condition, the antimony powder is completely dissolved in hot sulfuric acid to form a transparent solution.
[0044] It is found in the experiment that since the product antimony sulfate is easily hydrolyzed, water cannot be added during the reaction process, otherwise it will hydrolyze and precipitate into insoluble basic salt. Therefore, water should be avoided as much as possible in subsequent operations. When the dissolved ionic antimony element encounters phosphate, it immediately forms antimony phosphate, which is insoluble in sulfuric acid, so it immediately precipitates as antimony phosphate. Therefore, according to the ratio of antimony powder to concentrated sulfuric acid = 1:12, dissolve by heating, then add sodium dihydrogen phosphate dihydrate liquid (the liquid is obtained by heating solid sodium dihydrogen phosphate dihydrate to a temperature higher than its melting point of 60°C), stir, filter, wash, and dry to obtain antimony phosphate powder. The amount of sodium dihydrogen phosphate dihydrate liquid added and the heating temperature and time are investigated as follows: (1) Scheme 1: According to the ratio of antimony powder to concentrated sulfuric acid = 1:21, heat to 160°C for 10 minutes, and then cool to 60-80°C. Then add sodium dihydrogen phosphate dihydrate liquid (the liquid is obtained by heating solid sodium dihydrogen phosphate dihydrate to a temperature higher than its melting point of 60°C) according to the molar ratio of antimony powder to sodium dihydrogen phosphate = 1:1.3, stir for 10 minutes, then filter, wash, and dry at 115°C for 0.8h to obtain antimony phosphate powder.
[0045] (2) Scheme 2: According to the ratio of antimony powder to concentrated sulfuric acid = 1:21, heat to 140°C for 10 minutes, and then cool to 60-80°C. Then add sodium dihydrogen phosphate dihydrate liquid (the liquid is obtained by heating solid sodium dihydrogen phosphate dihydrate to a temperature higher than its melting point of 60°C) according to the molar ratio of antimony powder to sodium dihydrogen phosphate = 1:1.4, stir for 10 minutes, then filter, wash, and dry at 115°C for 0.8h to obtain antimony phosphate powder.
[0046] (3) Scheme 3: According to the ratio of antimony powder to concentrated sulfuric acid = 1:21, heat to 120°C for 15 minutes, and then cool to 60-80°C. Then add sodium dihydrogen phosphate dihydrate liquid (the liquid is obtained by heating solid sodium dihydrogen phosphate dihydrate to a temperature higher than its melting point of 60°C) according to the molar ratio of antimony powder to sodium dihydrogen phosphate = 1:1.5, stir for 10 minutes, then filter, wash, and dry at 110°C for 1h to obtain antimony phosphate powder.
[0047] (4) Procedure 4: Antimony powder: concentrated sulfuric acid = 1 :21 ratio, heated to 150°C for 15 minutes, until the antimony powder is completely dissolved, cooled to 60-80°C, then (molar ratio of antimony powder: sodium dihydrogen phosphate = 1 : 1.5) add sodium dihydrogen phosphate dihydrate liquid (this liquid is obtained by heating solid sodium dihydrogen phosphate dihydrate to 60°C above its melting point), stir for 10 minutes, then filter, wash, dry at 110°C for 1 h to obtain antimony phosphate powder.
[0048] (5) Procedure 5: Antimony powder: concentrated sulfuric acid = 1 :21 ratio, heated to 150°C for 20 minutes, until the antimony powder is completely dissolved, cooled to 60-80°C, then (molar ratio of antimony powder: sodium dihydrogen phosphate = 1 : 1.7) add sodium dihydrogen phosphate dihydrate liquid (this liquid is obtained by heating solid sodium dihydrogen phosphate dihydrate to 60°C above its melting point), stir for 10 minutes, then filter, wash, dry at 105°C for 1.2 h to obtain antimony phosphate powder.
[0049] The different products obtained were subjected to X-ray powder diffraction, the results of which can be seen in Figure 1 and Figure 2 , the diffraction patterns coincide with the diffraction peaks of the standard card (corresponding to Figure 1 the fourth line of the spectrum, namely ma4 PD3, Figure 2 the second line of the spectrum).
Claims
1. A method for preparing antimony phosphate directly from elemental antimony, characterized in that: The method is carried out according to the following steps: (1) antimony powder is added to concentrated sulfuric acid, mixed and heated to 140-160℃, and heated for 5-25 min, the mass ratio of the antimony powder and the concentrated sulfuric acid is 1:12-22, after the antimony powder is completely dissolved, it is cooled to 60-80℃, to obtain an antimony sulfate solution, which is ready for use; (2) solid sodium dihydrogen phosphate dihydrate is heated to 60℃ higher than its melting point to obtain a sodium dihydrogen phosphate dihydrate liquid, which is ready for use; (3) the sodium dihydrogen phosphate dihydrate liquid of step (2) is added to the antimony sulfate solution of step (1), and stirred, the molar ratio of the sodium dihydrogen phosphate dihydrate liquid to the antimony powder is 1.3-1.7:1, after stirring, it is filtered, the filtrate is discarded, the precipitate is collected, washed until the pH is greater than 6, and then dried to obtain antimony phosphate powder.
2. The method of claim 1, wherein the antimony is prepared by directly using elemental antimony. In the step (1), the antimony powder is added to concentrated sulfuric acid, mixed and heated to 150℃, and heated for 10-20 min.
3. The process for the preparation of antimony phosphates directly from elemental antimony according to claim 1, characterized in that: In the step (1), the mass ratio of the antimony powder to the concentrated sulfuric acid is 1:
21.
4. The process for the preparation of antimony phosphates directly from elemental antimony according to claim 1, characterized in that: In the step (3), the stirring time is 8-12 min.
5. The method of claim 4, wherein the method is characterized by: In the step (3), the stirring time is 10 min.
6. The process for the preparation of antimony phosphates directly from elemental antimony according to claim 1, characterized in that: In the step (3), the molar ratio of the sodium dihydrogen phosphate dihydrate liquid to the antimony powder is 1.5:
1.
7. The process for the preparation of antimony phosphates directly from elemental antimony according to claim 1, characterized by the fact that: In the step (3), the drying temperature is 105-115℃, and the drying time is 1 h.
8. The process for the preparation of antimony phosphates directly from elemental antimony according to claim 7, characterized by the fact that: In the step (3), the drying temperature is 110℃, and the drying time is 0.8-1.2 h.