Preparation method and application of hexahydroxyplatinic acid
By optimizing the preparation process of hexahydroxyplatinic acid, including controlling reaction conditions and parameters, the problems of low purity of products and slow reaction rates in the prior art are solved, and an efficient and stable preparation process and high-quality products are achieved.
Patent Information
- Application Number
- CN202510304275.2
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2025-03-14
- Publication Date
- 2025-06-27
AI Technical Summary
The method for preparing hexahydroxyplatinic acid in the prior art has problems such as low purity of the product, slow reaction rate and difficulty in controlling impurities, which affects its subsequent use.
By heating the hydrochloric acid and platinum powder and continuously adding nitric acid, the corresponding reaction steps are carried out with sodium hydroxide and glacial acetic acid after the reaction, the reaction conditions and parameters are accurately controlled to ensure that the platinum powder is fully dissolved and the reaction is complete.
It improves the yield and purity of hexahydroxyplatinic acid, ensures high quality and stability of the product, and is suitable for subsequent applications.
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Abstract
Description
Technical Field
[0001] The present invention belongs to the field of precious metal materials, and relates to a preparation method of a platinum-containing compound, in particular to a preparation method and application of hexahydroxyplatinate acid. Background Art
[0002] Judging from its name, hexahydroxyplatinate acid belongs to a coordination acid. The central ion is platinum (Pt) with an oxidation state of +4. It is coordinated by 6 hydroxyl groups (OH) around it to form a hexahydroxyplatinate(IV) complex ion, and then combines with two hydrogen ions H + to form H2Pt(OH)6.
[0003] In the prior art, hexahydroxyplatinate acid is usually prepared by reacting platinum oxide or metallic platinum with strong oxidizing acids such as concentrated nitric acid and concentrated sulfuric acid under certain conditions, and then through steps such as hydrolysis, or by hydrolysis and coordination reaction of platinum-containing complexes under alkaline conditions. The direct reaction of metallic platinum and concentrated nitric acid is relatively complex. Generally speaking, under different nitric acid concentrations and reaction conditions, the products are different, resulting in low product purity; and its reaction rate is slow, it is difficult to effectively control the introduction of impurities during the reaction process, and the product purity is not high, affecting subsequent use. Summary of the Invention
[0004] In view of the defects and deficiencies existing in the prior art, on the one hand, the present invention provides a preparation method of hexahydroxyplatinate acid; on the other hand, the present invention provides a preparation method of a platinum nitrate solution; on the third hand, the present invention provides a preparation method of a PtA solution.
[0005] On the one hand, the present invention provides a preparation method of hexahydroxyplatinate acid, including the following steps: Step 1, add hydrochloric acid and platinum powder into a reaction vessel, heat for reaction, and continuously dropwise add nitric acid into the reaction vessel at the same time. React until the platinum powder is completely dissolved, and then filter to obtain a chloroplatinic acid solution; Step 2, mix the chloroplatinic acid solution and sodium hydroxide solution to obtain solution B, control the pH of solution B to be 10 - 12, heat for reaction to obtain a sodium hexahydroxyplatinate solution; Step 3, dropwise add glacial acetic acid to the sodium hexahydroxyplatinate solution for reaction to obtain solution C. During the reaction process, maintain the pH value of the reaction system at 4 - 5, and then filter. The obtained solid particles are hexahydroxyplatinate acid.
[0006] Preferably, in Step 1, the reaction temperature is 95 - 105 °C; the heating rate is 1.6 - 3.5 °C / min.
[0007] Preferably, in step 1, the feeding ratio of platinum powder, nitric acid and hydrochloric acid is 1 kg∶0.6 - 1.0 L∶1.8 L - 3.0 L; the mass concentration of hydrochloric acid is 30% - 36%; the mass concentration of nitric acid is 60% - 68%.
[0008] More preferably, in step 1, the dropping rate of nitric acid is 7.5 - 15 L / h.
[0009] Preferably, before step 2 and after step 1, concentration and nitric acid removal are also included. Hydrochloric acid is dropped into the chloroplatinic acid solution until the moist starch potassium iodide does not change color, and then deionized water is added and heated for concentration.
[0010] More preferably, the molar ratio of platinum ions in the chloroplatinic acid solution to hydrochloric acid is 1∶4 - 6; the volume ratio of hydrochloric acid to deionized water is 1∶1 - 1.5.
[0011] More preferably, the heating temperature is 75 - 100 °C, and the heating time is 10 - 15 h.
[0012] Preferably, in step 2, the molar ratio of platinum ions in the chloroplatinic acid solution to sodium ions in the sodium hydroxide solution is 1∶2 - 4.
[0013] More preferably, the concentration of the sodium hydroxide solution is 3% - 5%.
[0014] Preferably, in step 2, the heating temperature is 100 - 120 °C, and the heating time is 8 - 12 h.
[0015] Preferably, in step 3, the reaction temperature is 40 - 50 °C, and the reaction time is 4 - 6 h.
[0016] In the second aspect, the present invention provides a preparation method of a platinum nitrate solution, including the following steps: Step 1, mixing hexahydroxyplatinate prepared by the above preparation method and nitric acid, and stirring until hexahydroxyplatinate dissolves to obtain a mixture D; Step 2, dropping a formic acid solution into the mixture D and heating for reaction. After the reaction is completed, it is cooled and filtered, and the obtained filtrate is the platinum nitrate solution.
[0017] Preferably, in step 1, the molar ratio of hexahydroxyplatinate to nitric acid is 1∶2 - 4; the mass concentration of nitric acid is 60% - 68%.
[0018] Preferably, in step 2, the molar ratio of platinum ions in the mixture D to formic acid is 1∶1.5 - 2.
[0019] Preferably, in step 2, the dropping rate of the formic acid solution is 20 - 30 mL / min, and the concentration of formic acid is 95.0% - 99.5%.
[0020] Preferably, in step 2, the reaction temperature is 70-75°C, the reaction time is 4-6 h; the heating rate is 2.3-2.5°C / min.
[0021] In a third aspect, the present invention provides a method for preparing a PtA solution, comprising: mixing the hexahydroxyplatinate acid prepared by the above method and ethanolamine, heating and reacting, and then filtering to obtain the solution which is the PtA solution.
[0022] Preferably, the molar ratio of hexahydroxyplatinate acid to ethanolamine is 1:3-5; the mass concentration of ethanolamine is 80%-90%.
[0023] Preferably, the heating temperature is 50-60°C, the heating time is 4-6 h; the heating rate is 2.5-3°C / min.
[0024] Compared with the prior art, one or more technical solutions provided by the present invention have at least one of the following beneficial effects: (1) By optimizing the production process and precisely controlling the addition sequence and parameters of raw materials, it is possible to ensure the full dissolution of platinum powder, while reducing the occurrence of side reactions, and improving the yield and purity of the product.
[0025] (2) During the nitrate removal process, strictly controlling the reaction nodes can effectively remove nitrate ions in the solution and improve the product purity. Specific Embodiments
[0026] The present invention provides the following specific technical solutions.
[0027] In a first aspect, the present invention provides a method for preparing hexahydroxyplatinate acid, comprising the following steps: Step 1, adding hydrochloric acid and platinum powder into a reaction vessel, heating for reaction, and continuously dropping nitric acid into the reaction vessel at the same time until the platinum powder is completely dissolved, and then filtering to obtain a chloroplatinic acid solution; Step 2, mixing the chloroplatinic acid solution and sodium hydroxide solution to obtain solution B, controlling the pH of solution B to be 10-12, heating and reacting to obtain a sodium hexahydroxyplatinate solution; Step 3, dropping glacial acetic acid into the sodium hexahydroxyplatinate solution for reaction to obtain solution C, maintaining the pH value of the reaction system at 4-5 during the reaction process, and then filtering, and the obtained solid particles are hexahydroxyplatinate acid.
[0028] The inventors have found through research that by precisely controlling parameters such as the dosage of raw materials, the addition sequence, the stirring speed, the reaction temperature, the pressure and the time, it is possible to ensure the full dissolution of platinum powder, while reducing the occurrence of side reactions. By controlling the steam pressure and the heating time, the reaction temperature is accurately regulated to ensure that the reaction proceeds under suitable conditions.
[0029] Preferably, in step 1, steam heating is used during heating, and the steam pressure is 0.2~0.4 MPa.
[0030] Preferably, in step 1, the reaction temperature is 95~105 °C; the heating rate is 1.6~3.5 °C / min.
[0031] Preferably, in step 1, the feeding ratio of platinum powder, nitric acid and hydrochloric acid is 1 kg∶0.6~1.0 L∶1.8 L~3.0 L; the mass concentration of hydrochloric acid is 30%~36%; the mass concentration of nitric acid is 60%~68%.
[0032] More preferably, in step 1, the dropping rate of nitric acid is 7.5~15 L / h.
[0033] Preferably, before step 2 after step 1, concentration and nitrate removal are also included. Hydrochloric acid is dropped into the chloroplatinic acid solution until the moist starch potassium iodide does not change color, and then deionized water is added and heated for concentration.
[0034] The inventor found through research that by strictly controlling the reaction nodes during nitrate removal, nitrate ions in the solution can be effectively removed, and the product purity can be improved. Adding deionized water during the concentration and nitrate removal process can cause a part of hydrochloric acid to be taken away by evaporation, which is beneficial to impurity control, reduces the dosage of sodium hydroxide in the next process, and lowers the cost.
[0035] More preferably, the molar ratio of platinum ions to hydrochloric acid in the chloroplatinic acid solution is 1∶4~6; the volume ratio of hydrochloric acid to deionized water is 1∶1~1.5; the mass concentration of hydrochloric acid is 30%~38%.
[0036] More preferably, the heating temperature is 75~85 °C, and the heating time is 10~15 h.
[0037] The inventor found through research that by maintaining the solution volume and controlling the reaction time, sufficient conditions are provided for the reaction, ensuring complete reaction, further improving the product yield and quality, and reducing the residue of unreacted raw materials.
[0038] Preferably, in step 2, the molar ratio of platinum ions in the chloroplatinic acid solution to sodium ions in the sodium hydroxide solution is 1∶2~4.
[0039] More preferably, the mass concentration of the sodium hydroxide solution is 10%~20%.
[0040] The inventor found through research that by precisely configuring the concentration and dosage of the sodium hydroxide solution and strictly controlling the addition rate of the chloroplatinic acid solution and the reaction temperature, the hydrolysis reaction can be ensured to proceed fully, enabling the full reaction of chloroplatinic acid and sodium hydroxide to generate high-purity sodium hexahydroxyplatinate (Na2Pt(OH)6), and improving the purity and quality of the product.
[0041] Preferably, in step 2, the heating temperature is 100~120°C and the heating time is 8~10 h.
[0042] Preferably, in step 3, the reaction temperature is 40~50°C and the reaction time is 4~6 h.
[0043] In a second aspect, the present invention provides a method for preparing a platinum nitrate solution, comprising the following steps: Step 1, mixing the hexahydroxyplatinate prepared by the above preparation method and nitric acid, and stirring until the hexahydroxyplatinate is dissolved to obtain a mixture D; Step 2, dropping a formic acid solution into the mixture D and heating for reaction, cooling after the reaction is completed, and filtering. The obtained filtrate is the platinum nitrate solution.
[0044] Preferably, in step 1, the molar ratio of hexahydroxyplatinate to nitric acid is 1∶2~4; the mass concentration of nitric acid is 60%~65%.
[0045] Preferably, in step 2, the molar ratio of platinum ions in the mixture D to formic acid is 1∶1.5~2.
[0046] Preferably, in step 2, the dropping rate of the formic acid solution is 20~30 mL / min.
[0047] Preferably, in step 2, the reaction temperature is 70~75°C, the reaction time is 10~15 h; the heating rate is 2.3~2.5°C / min.
[0048] In a third aspect, the present invention provides a method for preparing a PtA solution, comprising: mixing the hexahydroxyplatinate prepared by the above method and ethanolamine, heating for reaction and then filtering. The obtained solution is the PtA solution.
[0049] Preferably, the molar ratio of hexahydroxyplatinate to ethanolamine is 1∶3~5; the concentration of ethanolamine is 90%~99%.
[0050] Preferably, the heating temperature is 50~60°C, the heating time is 4~6 h; the heating rate is 2.5~3°C / min.
[0051] To make the technical problems, technical solutions and technical advantages to be solved by the present invention clearer, the following will be described in detail with specific examples, but the protection scope of the present invention is not limited to the following specific embodiments.
[0052] Unless otherwise defined, all professional terms used hereinafter have the same meaning as commonly understood by those skilled in the art. The professional terms used herein are only for the purpose of describing specific embodiments and are not intended to limit the protection scope of the present invention.
[0053] Unless otherwise specified, various raw materials, reagents, instruments, and equipment used in the present invention can be obtained through market purchases or can be prepared by existing methods.
[0054] Example 1: A method for preparing hexahydroxyplatinate acid, comprising the following steps: Step 1: Add 45 L of pure water to a 300-L enamel reactor equipped with a condenser (cooled by chilled water). Start stirring and control the stirring speed at 1.5 r / s using a frequency converter. Then add 45 L of analytical pure hydrochloric acid with a mass fraction of 36% from a 50-L glass elevated tank. Next, add 15 kg of platinum powder with a purity of ≥99.95%. Open the steam valve and control the steam pressure at 0.3 MPa. Heat the temperature inside the reactor to 100 °C within 45 min through steam. Then start dropping 15 L of analytical pure nitric acid with a mass fraction of 68% from the glass elevated tank and finish adding it within 1.5 h. After the dropping is complete, keep the reaction in a reflux state for 2.5 h until all the platinum powder is dissolved, obtaining a chloroplatinic acid solution.
[0055] Step 2: Evaporate and concentrate the chloroplatinic acid solution until its volume is 40 L. Drop 30 L of hydrochloric acid with a concentration of 38% from a 50-L elevated tank at a rate of 10 L / h to remove nitric acid. After adding 10 L of hydrochloric acid each time, rinse the reactor wall with a small amount of deionized water to promote the discharge of nitrate ions. During the dropping of hydrochloric acid, use a moist starch potassium iodide test paper to detect the solution. If the test paper turns blue, continue adding hydrochloric acid until the test paper no longer changes color, indicating that the removal of nitric acid is complete. Finally, add deionized water with the same volume as the added hydrochloric acid to the reactor, concentrate the solution to 40 L again, and finish concentrating after heating for 13 h. Turn off the heating and condenser, pass cooling water through the jacket for 30 min, cool the solution to below 50 °C, pump it to a 50-L glass filter for filtration with a diaphragm pump at a rate of 2.5 m 3 / h and transfer the chloroplatinic acid solution to a product barrel.
[0056] Step 3: After checking that a 1500-L enamel reactor and condensers with two or more stages are clean and available, open the condenser. Add 200 L of pure water to the reactor first, then add 40 kg of analytical pure sodium hydroxide solid with a purity of ≥99%, and then add 700 L of pure water to make a sodium hydroxide solution. Start stirring with a stirring speed of 1 r / s to dissolve all the sodium hydroxide, and control the solution temperature below 40 °C. Transfer the chloroplatinic acid solution to the reactor with a diaphragm pump at a rate of 2.5 m 3Slowly add it into the reaction kettle at a rate of / h (control the solution temperature below 40°C during the addition process). After the materials are added, rinse the inner wall of the reaction kettle with a small amount of pure water to ensure that the volume of the solution in the reaction kettle is 900 L, obtaining solution B. Detect the pH value of solution B, control pH = 11, then turn on the steam heating and heat the solution to 100°C within 45 min, and boil the solution for 12 h. During this period, use deionized water to maintain the solution volume. After the heating is completed, turn off the heating and pass cooling water through the jacket for 1 h to cool the solution to below 40°C, obtaining the sodium hexahydroxyplatinate solution.
[0057] Step 4: Transfer the sodium hexahydroxyplatinate solution to a 2000-L PP precipitation tank with stirring (frequency conversion control) and a bottom slope using a diaphragm pump, and start stirring at a stirring speed of 1 r / s. Add 99.5% analytical pure glacial acetic acid to the precipitation tank at a rate of 1 kg / min using a diaphragm pump, control the reaction process temperature < 50°C, and make the final pH value of the reaction reach 4 - 5. After the reaction is completed, transfer the solution to a 40-L glass filter for filtration using a diaphragm pump, and transfer the filtered mother liquor to a displacement tank for displacement using a diaphragm pump. Take out the filter cake and return it to the precipitation tank, rinse it twice with 80°C hot water, and wash it until the conductivity of the upper clear liquid < 500 μs / cm. If it is unqualified, continue to rinse until the conductivity < 500 μs / cm, and the obtained solid particles are hexahydroxyplatinic acid.
[0058] Example 2: A preparation method of hexahydroxyplatinic acid, comprising the following steps: Step 1: Add 45 L of pure water to a 300-L enamel reaction kettle equipped with a condenser (cooled by chilled water), start stirring, control the stirring speed at 1.5 r / s using a frequency converter, and then add 45 L of 30% analytical pure hydrochloric acid with a mass fraction from a 50-L glass high-level tank. Then add 15 kg of platinum powder with a purity ≥ 99.95%, turn on the steam valve, control the steam pressure at 0.2 MPa, heat up to 90°C within 55 min, and then start dropping 15 L of 60% analytical pure nitric acid with a mass fraction from the glass high-level tank and add it up within 1.5 h. After the dropping is completed, keep the reaction in a reflux state for 2.5 h until all the platinum powder is dissolved, obtaining the chloroplatinic acid solution.
[0059] Step 2, evaporate and concentrate the chloroplatinic acid solution until the volume of the chloroplatinic acid solution is 40 L. Add 30 L of hydrochloric acid with a concentration of 30% dropwise from a 50 L high-level tank at a rate of 10 L / h to remove nitrate. After adding 10 L of hydrochloric acid each time, rinse the inner wall of the reaction kettle with a small amount of deionized water to promote the discharge of nitrate. During the dropwise addition of hydrochloric acid, use a moist starch potassium iodide test paper to detect the solution. If the test paper turns blue, continue to add hydrochloric acid until the test paper no longer changes color, indicating that the nitrate removal is complete. Finally, add deionized water with the same volume as the added hydrochloric acid to the reaction kettle, concentrate the solution to 40 L again, and after heating for 13 h, the concentration is completed. Turn off the heating and condenser, and pass cooling water through the jacket for 30 min to cool the solution to below 50 °C, and then pump it to a 50 L glass filter for filtration with a vacuum pump, and then transfer the chloroplatinic acid solution to the product barrel at a rate of 2.5 m 3 / h with a diaphragm pump.
[0060] Step 3, after checking that the 1500 L enamel reaction kettle and condensers above two levels are clean and available, open the condenser, first add 200 L of pure water to the reaction kettle, then add 30 kg of analytical pure sodium hydroxide solid with a purity of ≥99%, and then add 700 L of pure water to make a sodium hydroxide solution. Start stirring, and the stirring speed is 1 r / s to completely dissolve the sodium hydroxide, and control the solution temperature below 40 °C. Transfer the chloroplatinic acid solution to the reaction kettle slowly at a rate of 2.5 m 3 / h with a diaphragm pump (the solution temperature is controlled below 40 °C during the addition process). After adding the materials, rinse the inner wall of the reaction kettle with a small amount of pure water to ensure that the volume of the solution in the reaction kettle is 900 L to obtain solution B. Detect the pH value of solution B and control pH = 10, then turn on the steam heating and heat the solution to 100 °C within 45 min, and boil the solution for 8 h, and maintain the solution volume with deionized water during this period. After the heating is completed, turn off the heating, and pass cooling water through the jacket for 1 h to cool the solution to below 40 °C, and then sodium hexahydroxyplatinate solution is obtained.
[0061] Step 4, transfer the sodium hexahydroxyplatinate solution to a 2000 L PP precipitation tank with stirring (frequency conversion control) and a bottom slope at a rate of 1 - 4 m 3 / h with a diaphragm pump, and start stirring, and the stirring speed is 1 r / s. Add 99.5% analytical pure glacial acetic acid to the precipitation tank at a rate of 1 kg / min with a diaphragm pump, control the reaction process temperature < 40 °C, and make the final pH value of the reaction reach 4 - 5. After the reaction is completed, transfer the solution to a 40 L glass filter for filtration with a diaphragm pump, and transfer the filtered mother liquor to a replacement tank for replacement. Take out the filter cake and return it to the precipitation tank, rinse it twice with 80 °C hot water, and wash it until the conductivity of the upper clear liquid < 500 μs / cm. If it is unqualified, continue to rinse until the conductivity < 500 μs / cm, and the obtained solid particles are hexahydroxyplatonic acid.
[0062] Example 3: A preparation method of hexahydroxyplatinate acid, comprising the following steps: Step 1: Add 45 L of pure water to a 300-L enamel reactor equipped with a condenser (cooled by chilled water). Start stirring and control the stirring speed at 1.5 r / s using a frequency converter. Then add 45 L of analytical pure hydrochloric acid with a mass fraction of 30% from a 50-L glass elevated tank. Next, add 15 kg of platinum powder with a purity of ≥99.95%. Open the steam valve and control the steam pressure at 0.4 MPa. Heat up to 90 °C within 30 min. Then start dropping 15 L of analytical pure nitric acid with a mass fraction of 60% from the glass elevated tank and finish adding it within 1.5 h. After the dropping is complete, keep the reaction in a reflux state for 2.5 h until all the platinum powder is dissolved to obtain a chloroplatinic acid solution.
[0063] Step 2: Evaporate and concentrate the chloroplatinic acid solution until its volume is 40 L. Drop 30 L of hydrochloric acid with a concentration of 38% from a 50-L elevated tank at a rate of 15 L / h to drive out nitrate. After adding 10 L of hydrochloric acid each time, rinse the reactor wall with a small amount of deionized water to promote the discharge of nitrate ions. During the dropping of hydrochloric acid, use a moist starch potassium iodide test paper to detect the solution. If the test paper turns blue, continue adding hydrochloric acid until the test paper does not change color, indicating that the nitrate expulsion is complete. Finally, add deionized water with the same volume as the added hydrochloric acid to the reactor, and concentrate the solution to 40 L again. It takes 13 h to complete the nitrate expulsion by heating until the concentration is achieved. Turn off the heating and the condenser, and pass cooling water through the jacket for 30 min to cool the solution to below 50 °C. Then pump it to a 50-L glass filter for filtration using a diaphragm pump, and transfer the chloroplatinic acid solution to a product barrel at a rate of 2.5 m 3 / h.
[0064] Step 3: After checking that a 1500-L enamel reactor and condensers with two or more stages are clean and available, open the condenser. First, add 200 L of pure water to the reactor, then add 45 kg of analytical pure sodium hydroxide solid with a purity of ≥99%, and then add 700 L of pure water to make a sodium hydroxide solution. Start stirring at a speed of 1 r / s to dissolve all the sodium hydroxide, and control the solution temperature below 40 °C. Slowly add the chloroplatinic acid solution to the reactor at a rate of 2.5 m 3 / h using a diaphragm pump (control the solution temperature below 40 °C during the addition process). After the addition of the material is complete, rinse the reactor wall with a small amount of pure water to ensure that the volume of the solution in the reactor is 900 L to obtain solution B. Detect the pH value of solution B and control it at pH = 12. Then turn on the steam heating and heat the solution to 100 °C within 45 min, and boil the solution for 8 h. During this period, maintain the solution volume with deionized water. After the heating is completed, turn off the heating and pass cooling water through the jacket for 1 h to cool the solution to below 40 °C, and then obtain a sodium hexahydroxyplatinate solution.
[0065] Step 4: Transfer the sodium hexahydroxyplatinate solution to a 2000L PP precipitation tank with stirring (frequency conversion control) and a bottom slope using a diaphragm pump (1 - 4m 3 / h). Start the stirring, and the stirring speed is 1 r / s. Add 99.5% analytical pure glacial acetic acid to the precipitation tank at a rate of 1 kg / min using a diaphragm pump, and control the temperature during the reaction process to be < 50°C to make the final pH value of the reaction reach 5 - 6. After the reaction ends, transfer the solution to a 40L glass filter using a diaphragm pump for filtration, and transfer the filtered mother liquor to a replacement tank for replacement. Take out the filter cake and return it to the precipitation tank, rinse it twice with 80°C hot water, and wash it until the conductivity of the supernatant is < 500 μs / cm. If it is unqualified, continue rinsing until the conductivity is < 500 μs / cm. The obtained solid particles are sodium hexahydroxyplatinate acid.
[0066] Comparative Example 1: A preparation method of sodium hexahydroxyplatinate acid, different from Example 1 in that in Step 3, after checking that a 1500L enamel reaction kettle and condensers with two or more stages are clean and available, open the condenser, first add 200L of pure water to the reaction kettle, then add 25 kg of analytical pure sodium hydroxide solid with a purity ≥ 99%, and then add 700L of pure water to make a sodium hydroxide solution. Start the stirring, and the stirring speed is 1 r / s to completely dissolve the sodium hydroxide, and control the solution temperature to be below 40°C. Slowly add the chloroplatinic acid solution to the reaction kettle at a rate of 2.5m 3 / h using a diaphragm pump (control the solution temperature to be below 40°C during the addition process). After the materials are added, rinse the inner wall of the reaction kettle with a small amount of pure water to ensure that the volume of the solution in the reaction kettle is 900L to obtain Solution B. Detect the pH value of Solution B and control pH = 7, then turn on the steam heating and heat the solution to 100°C within 45 min, and boil the solution for 12 h, maintaining the solution volume with deionized water during this period. After the heating ends, turn off the heating, pass cooling water through the jacket for 1 h to cool the solution to below 40°C, and thus obtain the sodium hexahydroxyplatinate solution.
[0067] Test the purity and yield of the sodium hexahydroxyplatinate acid prepared in Examples 1 - 3, and the data are shown in Table 1.
[0068] Table 1 Purity and yield of the sodium hexahydroxyplatinate acid prepared in Examples 1 - 3 As can be seen from Table 1, the yield and purity of the sodium hexahydroxyplatinate acid prepared by the preparation process provided by the present invention are at relatively high levels and can meet the requirements of most manufacturers on the market.
[0069] By comparing Example 1 and Comparative Example 1, it can be seen that the present invention can further improve the purity and yield of the sodium hexahydroxyplatinate acid by controlling the parameters during the reaction process.
[0070] Example 4: A preparation method of a platinum nitrate solution, comprising the following steps: Step 1, mix the hexahydroxyplatinate acid prepared in Example 1 and nitric acid with a mass fraction of 65%. The molar ratio of hexahydroxyplatinate acid to nitric acid is 1:3. Stir at a stirring rate of 1 r / s until the hexahydroxyplatinate acid is dissolved to obtain mixture D.
[0071] Step 2, turn on the steam and heat to 75 °C within 30 min. Dropwise add 5 L of a formic acid solution with a concentration of 95% to mixture D at a rate of 25 mL / min. The molar ratio of platinum ions to formic acid in the obtained mixed solution is 1:1.8. Then maintain the reaction temperature at 75 °C and react for 5 h. Then continue heating and concentrating, and then filter. The obtained filtrate is the platinum nitrate solution.
[0072] Example 5: A preparation method of a platinum nitrate solution, comprising the following steps: Step 1, mix the hexahydroxyplatinate acid prepared in Example 1 and nitric acid with a mass fraction of 60%. The molar ratio of hexahydroxyplatinate acid to nitric acid is 1:2. Stir at a stirring rate of 1 r / s until the hexahydroxyplatinate acid is dissolved to obtain mixture D.
[0073] Step 2, turn on the steam and heat to 70 °C within 30 min. Dropwise add 5 L of a formic acid solution with a concentration of 97% to mixture D at a rate of 20 mL / min. The molar ratio of platinum ions to formic acid in the obtained mixed solution is 1:1.5. Then maintain the reaction temperature at 70 °C and react for 4 h. Then continue heating and concentrating, and then filter. The obtained filtrate is the platinum nitrate solution.
[0074] Example 6: A preparation method of a platinum nitrate solution, comprising the following steps: Step 1, mix the hexahydroxyplatinate acid prepared in Example 1 and nitric acid with a mass fraction of 68%. The molar ratio of hexahydroxyplatinate acid to nitric acid is 1:4. Stir at a stirring rate of 1 r / s until the hexahydroxyplatinate acid is dissolved to obtain mixture D.
[0075] Step 2, turn on the steam and heat to 73 °C within 30 min. Dropwise add 5 L of a formic acid solution with a concentration of 99.5% to mixture D at a rate of 30 mL / min. The molar ratio of platinum ions to formic acid in the obtained mixed solution is 1:2. Then maintain the reaction temperature at 73 °C and react for 6 h. Then continue heating and concentrating, and then filter. The obtained filtrate is the platinum nitrate solution.
[0076] Test the purity and yield of the platinum nitrate solutions prepared in Examples 4 to 6. The data is shown in Table 2.
[0077] Table 2 Purity and yield of the platinum nitrate solutions prepared in Examples 4 to 6 As can be seen from Table 2, the yield and purity of the platinum nitrate solution prepared by the preparation method provided by the present invention are both at a relatively high level, which can meet the requirements of most manufacturers in the market.
[0078] Example 7: A preparation method of a PtA solution, comprising the following steps: Add 23 Kg of hexahydroxyplatinate acid prepared in Example 1 to an enamel reactor with a condenser (1 section of 2.5 m 2 ) and variable-frequency control of stirring, then add 80 L of pure water, and start stirring and pulping. Turn on the steam and heat to 55 °C within 20 min. Add 15 kg of analytical pure ethanolamine with a mass fraction of 99% from a 50 L high-level tank, and continue stirring and reacting for 4 h to ensure that all solids are completely dissolved. Pass in cooling water to cool down to 40 °C, pump it to the high-level tank with a vacuum and then transfer it to a 50 L PP filter for filtration. The resulting solution is the PtA solution.
[0079] Example 8: A preparation method of a PtA solution, comprising the following steps: Add 23 Kg of hexahydroxyplatinate acid prepared in Example 2 to an enamel reactor with a condenser (1 section of 2.5 m 2 ) and variable-frequency control of stirring, then add 80 L of pure water, and start stirring and pulping. Turn on the steam and heat to 50 °C within 20 min. Add 20 kg of analytical pure ethanolamine with a mass fraction of 99% from a 50 L high-level tank, and continue stirring and reacting for 5 h to ensure that all solids are completely dissolved. Pass in cooling water to cool down to 40 °C, pump it to the high-level tank with a vacuum and then transfer it to a 50 L PP filter for filtration. The resulting solution is the PtA solution.
[0080] Example 9: A preparation method of a PtA solution, comprising the following steps: Add 23 Kg of hexahydroxyplatinate acid prepared in Example 3 to an enamel reactor with a condenser (1 section of 2.5 m 2 ) and variable-frequency control of stirring, then add 80 L of pure water, and start stirring and pulping. Turn on the steam and heat to 60 °C within 20 min. Add 25 kg of analytical pure ethanolamine with a mass fraction of 99% from a 50 L high-level tank, and continue stirring and reacting for 6 h to ensure that all solids are completely dissolved. Pass in cooling water to cool down to 40 °C, pump it to the high-level tank with a vacuum and then transfer it to a 50 L PP filter for filtration. The resulting solution is the PtA solution.
[0081] Test the purity and yield of the PtA solutions prepared in Examples 7 to 9, and the data are shown in Table 3.
[0082] Table 3 Purity and yield of PtA solutions prepared in Examples 7 to 9 As can be seen from Table 3, the yield and purity of the PtA solution prepared by the preparation process provided by the present invention are both at a relatively high level, meeting the requirements of most manufacturers on the market.
[0083] The above-described embodiments are only preferred specific embodiments of the present invention, but the protection scope of the present invention is not limited thereto. Any person skilled in the art within the technical scope of the present invention, according to the technical solution and its concept of the present invention, makes equivalent substitutions or changes, and should be covered by the protection scope of the present invention.
Claims
1. A method for preparing hexahydroxyplatinic acid, characterized in that: The steps include: Step 1, adding hydrochloric acid and platinum powder into a reaction container, heating to react, while continuously adding nitric acid into the reaction container, reacting until the platinum powder is completely dissolved, and then filtering to obtain a chloroplatinic acid solution; Step 2, mixing chloroplatinic acid solution and sodium hydroxide solution to obtain solution B, controlling the pH of solution B to be 10-12, heating for reaction, and obtaining sodium hexahydroxyplatinate solution; Step 3, adding glacial acetic acid dropwise to the sodium hexahydroxyplatinate solution to react to obtain solution C, maintaining the pH value of the reaction system at 4-5 during the reaction, and then filtering to obtain solid particles, namely hexahydroxyplatinic acid.
2. The method for preparing hexahydroxyplatinic acid according to claim 1, characterized in that: In step 1, the reaction temperature is 95-105°C; the heating rate is 1.6-3.5°C / min; in step 1, the feed ratio of platinum powder, nitric acid and hydrochloric acid is 1kg: 0.6-1.0L: 1.8L-3.0L; the mass concentration of hydrochloric acid is 30%-36%; and the mass concentration of nitric acid is 60%-68%.
3. The method for preparing hexahydroxyplatinic acid according to claim 1, characterized in that: After step 1 and before step 2, the process further includes concentrating and removing nitrate, wherein hydrochloric acid is added dropwise to the chloroplatinic acid solution until the wet starch potassium iodide does not change color, and then deionized water is added and the mixture is heated and concentrated.
4. The method for preparing hexahydroxyplatinic acid according to claim 3, characterized in that: The molar ratio of platinum ions to hydrochloric acid in the chloroplatinic acid solution is 1:4-6; the volume ratio of hydrochloric acid to deionized water is 1:1-1.5; the heating temperature is 75-100°C, and the heating time is 10-15h.
5. The method for preparing hexahydroxyplatinic acid according to claim 1, characterized in that: In step 2, the molar ratio of platinum ions in the chloroplatinic acid solution to sodium ions in the sodium hydroxide solution is 1:2-4.
6. The method for preparing hexahydroxyplatinic acid according to claim 1, characterized in that: In step 2, the heating temperature is 100-120° C., and the heating time is 8-12 h; in step 3, the reaction temperature is 40-50° C., and the reaction time is 4-6 h.
7. A method for preparing platinum nitrate, characterized in that: The steps include: Step 1, mixing hexahydroxyplatinic acid prepared by the preparation method according to any one of claims 1 to 6 and nitric acid, and stirring until the hexahydroxyplatinic acid is dissolved to obtain a mixture D; Step 2, adding formic acid solution dropwise to mixture D and heating for reaction, cooling after the reaction is completed, filtering, and obtaining a filtrate is a platinum nitrate solution.
8. The method for preparing platinum nitrate as claimed in claim 7, wherein In step 1, the molar ratio of hexahydroxyplatinic acid to nitric acid is 1:2-4; the mass concentration of nitric acid is 60%-68%; in step 2, the molar ratio of platinum ions to formic acid in mixture D is 1:1.5-2; the reaction temperature is 70-75°C, and the reaction time is 4-6h.
9. A method for preparing a PtA solution, characterized in that: include: The hexahydroxyplatinic acid and ethanolamine prepared by the preparation method according to any one of claims 1 to 6 are mixed, heated for reaction, and then filtered to obtain a solution which is a PtA solution.
10. The method for preparing a PtA solution according to claim 9, characterized in that: The molar ratio of hexahydroxyplatinic acid to ethanolamine is 1:3-5; the heating temperature is 50-60°C, and the heating time is 4-6h.