Preparation method of high-purity iridium powder

Abstract

The invention relates to the technical field of high-purity noble metal catalysts, in particular to a preparation method of high-purity iridium powder, which comprises the following steps: iridium dissolution and liquid preparation: adding chloroiridic acid into deionized water, stirring and dissolving, and filtering to remove insoluble substances to obtain an iridium solution A; complexing and precipitating iridium: adding didecyl dimethyl ammonium chloride into the iridium solution A, heating to 80-90 DEG C, separating out a large amount of yellow precipitate, and filtering when the solution becomes colorless from orange red to obtain iridium-containing precipitate B; recrystallization: adding the iridium-containing precipitate B into deionized water for recrystallization, and filtering to obtain an iridium-containing precipitate C; dissolving the iridium-containing precipitate C to prepare a solution, namely adding the iridium-containing precipitate C into dilute ammonia water with the pH value of 8-9 to be dissolved to obtain an iridium solution D, and filtering to remove trace insoluble impurities; and reducing to obtain high-purity iridium powder: adding hydrazine hydrate into the iridium solution D under a micro-boiling condition for reaction, filtering after reduction to obtain iridium powder, boiling and washing with aqua regia, filtering, washing with deionized water, and drying in vacuum to obtain the high-purity iridium powder.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of high-purity noble metal catalysts, in particular to a preparation method of high-purity iridium powder. BACKGROUND

[0002] Iridium (Ir) is a transition metal in the 9th group of the 6th period of the periodic table, with the element symbol Ir and atomic number 77. It is a silvery-white metal with a luster, cubic crystal system, and a relative density of 22.56 g / cm 3 (20℃), melting point 2443℃, and boiling point 4437℃. Iridium has stable chemical properties and can maintain good mechanical properties in an atmospheric atmosphere above 1600℃. It also has good oxidation resistance at high temperatures. High-purity iridium can be processed into target materials for thin film deposition processes, such as OLED light-emitting materials and integrated circuit manufacturing. In fuel cells, photovoltaic devices, and hydrogen energy technology, high-purity iridium is used as an electric contact material, high-temperature electrode, and other key components due to its excellent electrical conductivity and oxidation resistance. In addition, high-purity iridium has become an irreplaceable material in high-tech fields such as aerospace engines, power station gas turbines, isotope batteries, and supersonic wind tunnel nozzles.

[0003] Iridium is one of the platinum group metals, and the chemical properties of platinum group metals are very similar, making it difficult to separate platinum group metals. The separation and purification of iridium is particularly difficult. With the development of technology, the purity requirements for iridium are becoming higher and higher.

[0004] The method disclosed by Chinese patent 201810275541.3 is to add iridium powder and hydrochloric acid into a reaction kettle and pass in chlorine, then when the kettle pressure drops to normal pressure, add concentrated hydrochloric acid in batches and continue to stir, and after removing the free chlorine, solid-liquid separation is carried out, and the obtained filtrate is chloroiridic acid solution. The method uses chlorine oxidation, which is a highly toxic and dangerous operation. If the sealing performance of the equipment does not meet the standards, it will cause human poisoning and environmental pollution. The method disclosed by Chinese patent 201010290275.5 is to add hydrochloric acid and iridium powder in a U-shaped electrolytic cell, load alternating current on both ends of the electrodes of the U-shaped electrolytic cell, and directly dissolve the iridium powder in the hydrochloric acid to obtain an aqueous chloroiridic acid solution. The method cannot be carried out in a sealed environment during electrolysis, and the volatilization of hydrogen chloride and the chlorine generated at the anode result in a very poor operating environment. The method disclosed by Chinese patent 201010567367.3 dissolves the iridium-containing material with hydrochloric acid, adds nitric acid and NH4Cl to react to obtain iridium-platinum mixed ammonium salt, adds hydrazine hydrate to reduce and precipitate other metals, obtains refined (NH4)2IrCl6 crystals, and calcines and reduces with hydrogen to prepare iridium powder. The method is slow in preparing iridium powder, and the purity is not high. There are documents that use P204 extraction to remove base metal cations, N235 extraction to remove noble metal impurities existing in complex anions, H2 reduction to remove rhodium and other metal impurities, and 732# resin exchange to remove trace amounts of base metal cations NH4Cl precipitation iridium, H2 reduction of iridium-HF removal of silicon process to prepare iridium matrix. The purity of the developed iridium matrix is as high as 99.999%, and 16 kinds of impurity elements in the iridium powder are analyzed, including Rh, Pt, Pd, Au, Ag, Cu, Fe, Ni, Al, Pb, Si, Mn, Mg, Sn, Zn and Ru.

[0005] In summary, most of the existing iridium purification methods can obtain products with a purity of 99.9-99.99%; the preparation of 5N grade (99.999%) iridium powder is relatively less studied, and the process is relatively complex. Therefore, the efficient preparation of high-purity iridium powder is of great significance. SUMMARY

[0006] The purpose of the present application is to solve the technical problems in the prior art, and to provide a preparation method of high-purity iridium powder. The method does not add any metal element-containing reagent, does not produce any toxic and harmful gas during the reaction, and has simple and stable production process operation.

[0007] The technical solution to achieve the purpose of the present application is as follows: A preparation method of high-purity iridium powder, characterized in that it comprises the following steps: Step one, iridium dissolution solution: chloroiridic acid is added to deionized water and stirred to dissolve, and insoluble substances are removed by filtration to obtain an iridium solution A, wherein the mass ratio of chloroiridic acid to deionized water is 1:6; Step two, complexing and precipitating iridium: add didecyldimethylammonium chloride into the iridium solution A and heat to 80-90 DEG C, a large amount of yellow precipitate is separated out, when the solution changes from orange red to colorless, filter to obtain the iridium-containing precipitate B, wherein the amount of didecyldimethylammonium chloride added is 4-5 times of the molar amount of chloroiridic acid; Step three, recrystallization: add the iridium-containing precipitate B into deionized water for recrystallization, filter to obtain the iridium-containing precipitate C; Step four, dissolving the iridium-containing precipitate C to form a solution: add the iridium-containing precipitate C into ammonia water with the mass of chloroiridic acid being 5 times and the pH being 8-9 to dissolve, obtain the iridium solution D and filter to remove trace amounts of insoluble impurities; Step five, reducing to obtain high-purity iridium powder: add the iridium solution D into hydrazine hydrate with the mass of chloroiridic acid being 4.5-5.5 times under the condition of micro-boiling, filter to obtain the iridium powder after reduction, filter and wash with deionized water after aqua regia boiling, and vacuum dry to obtain the high-purity iridium powder.

[0008] Further, in step one, the chloroiridic acid is black needle-shaped crystal, and the iridium content is 35%.

[0009] Further, in step two, the didecyldimethylammonium chloride is light yellow transparent liquid, and the purity is >99.5%.

[0010] Further, in step four, the ammonia water is electronic grade ammonia water, and the mass concentration is 28%.

[0011] Further, in step five, the hydrazine hydrate is colorless transparent liquid, and the mass concentration of the high-purity hydrazine hydrate is 80%.

[0012] Further, in step five, the hydrochloric acid in the aqua regia is electronic grade hydrochloric acid, and the mass concentration is 36%; the nitric acid in the aqua regia is electronic grade nitric acid, and the mass concentration is 70%; the conductivity of the deionized water should be <0.1 mu S / cm, the iridium powder is washed for 3 times, and vacuum drying is 6 h.

[0013] The beneficial effects of the present application are as follows: 1. In the preparation process of the present application, no metal element-containing reagent is added, and no toxic and harmful gas is generated in the reaction process, which is friendly to the environment.

[0014] 2. The production process of the present application is short, simple and stable, the direct yield of metallic iridium reaches more than 95%, and the purity of the high-purity iridium powder prepared by the present application is greater than 99.999%. BRIEF DESCRIPTION OF DRAWINGS

[0015] Figure 1 The appearance of the high-purity iridium powder prepared by the present application is shown in the figure. DETAILED DESCRIPTION

[0016] With reference to the accompanying drawings, the technical solutions in the embodiments of the present application will be clearly and completely described below. Obviously, the described embodiments are only a part of the embodiments of the present application, rather than all the embodiments of the present application. Based on the embodiments of the present application, all the other embodiments obtained by a person of ordinary skill in the art without creative effort belong to the protection scope of the present application.

[0017] Embodiment 1

[0018] A preparation method of high-purity iridium powder comprises the following steps: (1) iridium solution preparation: 100 g of chloroiridic acid is added into 600 g of deionized water to be stirred and dissolved, and then filtered to remove insoluble substances to obtain iridium solution A; (2) complexation and iridium precipitation: 263.7 g of dipentadecyldimethylammonium chloride is added into the iridium solution A, and then heated to 80℃, a large amount of yellow precipitate is precipitated, and when the solution changes from orange red to colorless, 165.3 g of iridium-containing precipitate B is obtained by filtration.

[0019] (3) recrystallization: 165.3 g of the iridium-containing precipitate B is added into deionized water to be recrystallized, and then filtered to obtain 153.4 g of iridium-containing precipitate C.

[0020] (4) iridium-containing precipitate C solution preparation: 153.4 g of the iridium-containing precipitate C is added into 500 g of dilute ammonia water with pH of 8-9 to be dissolved, and then filtered to obtain iridium solution D and remove trace amounts of insoluble impurities; (5) reduction to obtain high-purity iridium powder: 45.0 g of hydrazine hydrate is added into the iridium solution D under micro-boiling conditions to be stirred and reacted, and then filtered to obtain iridium powder after the reduction is completed, and then the iridium powder is added into 40 ml of aqua regia to be boiled and washed for 1 hour, and then filtered and washed with deionized water for 3 times, and then transferred to a vacuum oven to be dried at 80℃ for 6 hours to obtain 32.3 g of high-purity iridium powder, and the yield is 92.3%.

[0021] Embodiment 2

[0022] A preparation method of high-purity iridium powder comprises the following steps: (1) iridium solution preparation: 100 g of chloroiridic acid is added into 600 g of deionized water to be stirred and dissolved, and then filtered to remove insoluble substances to obtain iridium solution A; (2) complexation and iridium precipitation: 273.9 g of dipentadecyldimethylammonium chloride is added into the iridium solution A, and then heated to 83℃, a large amount of yellow precipitate is precipitated, and when the solution changes from orange red to colorless, 169.2 g of iridium-containing precipitate B is obtained by filtration.

[0023] (3) recrystallization: 169.2 g of the iridium-containing precipitate B is added into deionized water to be recrystallized, and then filtered to obtain 154.7 g of iridium-containing precipitate C.

[0024] (4) Dissolution of the iridium-containing precipitate C to form a solution: 154.7 g of the iridium-containing precipitate C was dissolved in 500 g of dilute ammonia water with a pH of 8-9 to obtain an iridium solution D, which was filtered to remove trace amounts of insoluble impurities; (5) Reduction to obtain high-purity iridium powder: the iridium solution D was added to 47.8 g of hydrazine hydrate under micro-boiling conditions for stirring reaction. After the reduction was completed, the iridium powder was obtained by filtration. After being added to 40 ml of aqua regia and boiled for 1 hour, the iridium powder was filtered, washed with deionized water for 3 times, and then transferred to a vacuum oven for drying at 80°C for 6 hours to obtain 33.2 g of high-purity iridium powder with a yield of 94.6%.

[0025] Example 3

[0026] A method for preparing high-purity iridium powder, comprising the following steps: (1) Dissolution of iridium to form a solution: 100 g of chloroiridic acid was added to 600 g of deionized water for stirring and dissolution, and the insoluble substances were removed by filtration to obtain an iridium solution A; (2) Complexation and precipitation of iridium: 286.6 g of dipdecyl dimethyl ammonium chloride was added to the iridium solution A, and then heated to 85°C. A large amount of yellow precipitate was precipitated, and the solution changed from orange red to colorless. After filtration, 169.8 g of iridium-containing precipitate B was obtained.

[0027] (3) Recrystallization: 169.8 g of the iridium-containing precipitate B was added to deionized water for recrystallization, and 158.6 g of iridium-containing precipitate C was obtained by filtration.

[0028] (4) Dissolution of the iridium-containing precipitate C to form a solution: 158.6 g of the iridium-containing precipitate C was dissolved in 500 g of dilute ammonia water with a pH of 8-9 to obtain an iridium solution D, which was filtered to remove trace amounts of insoluble impurities; (5) Reduction to obtain high-purity iridium powder: the iridium solution D was added to 52.3 g of hydrazine hydrate under micro-boiling conditions for stirring reaction. After the reduction was completed, the iridium powder was obtained by filtration. After being added to 40 ml of aqua regia and boiled for 1 hour, the iridium powder was filtered, washed with deionized water for 3 times, and then transferred to a vacuum oven for drying at 80°C for 6 hours to obtain 33.2 g of high-purity iridium powder with a yield of 94.6%.

[0029] Example 4

[0030] A method for preparing high-purity iridium powder, comprising the following steps: (1) Dissolution of iridium to form a solution: 100 g of chloroiridic acid was added to 600 g of deionized water for stirring and dissolution, and the insoluble substances were removed by filtration to obtain an iridium solution A; (2) Complexation and precipitation of iridium: 286.6 g of dipdecyl dimethyl ammonium chloride was added to the iridium solution A, and then heated to 85°C. A large amount of yellow precipitate was precipitated, and the solution changed from orange red to colorless. After filtration, 169.8 g of iridium-containing precipitate B was obtained.

[0031] (3) Recrystallization: 171.6 grams of the iridium-containing precipitate B is added to deionized water for recrystallization, and 159.3 grams of an iridium-containing precipitate C is obtained by filtration.

[0032] (4) Dissolution of the iridium-containing precipitate C: 159.1 grams of the iridium-containing precipitate C is added to 500 grams of dilute ammonia water with a pH of 8-9 for dissolution, and an iridium solution D is obtained and filtered to remove trace amounts of insoluble impurities; (5) Reduction to obtain high-purity iridium powder: the iridium solution D is added to 56.3 grams of hydrazine hydrate under micro-boiling conditions for stirring and reaction, and the iridium powder is obtained by filtration after the reduction is completed. After being added to 40 milliliters of aqua regia, the iridium powder is boiled and washed for 1 hour, filtered, washed with deionized water for 3 times, and transferred to a vacuum oven for drying at 80°C for 6 hours to obtain 33.49 grams of high-purity iridium powder with a yield of 95.7%.

[0033] Example 5

[0034] A method for preparing high-purity iridium powder, comprising the following steps: (1) Iridium solution preparation: 100 grams of chloro iridic acid is added to 600 grams of deionized water for stirring and dissolution, and an iridium solution A is obtained by filtration to remove insoluble substances; (2) Complexation and iridium precipitation: 325.3 grams of dipdecyl dimethyl ammonium chloride is added to the iridium solution A, and the solution is heated to 85°C. A large amount of yellow precipitate is precipitated, and the solution changes from orange red to colorless. After filtration, 170.9 grams of an iridium-containing precipitate B is obtained; (3) Recrystallization: 170.9 grams of the iridium-containing precipitate B is added to deionized water for recrystallization, and 158.8 grams of an iridium-containing precipitate C is obtained by filtration; (4) Dissolution of the iridium-containing precipitate C: 158.8 grams of the iridium-containing precipitate C is added to 500 grams of dilute ammonia water with a pH of 8-9 for dissolution, and an iridium solution D is obtained and filtered to remove trace amounts of insoluble impurities; (5) Reduction to obtain high-purity iridium powder: the iridium solution D is added to 56.2 grams of hydrazine hydrate under micro-boiling conditions for stirring and reaction, and the iridium powder is obtained by filtration after the reduction is completed. After being added to 40 milliliters of aqua regia, the iridium powder is boiled and washed for 1 hour, filtered, washed with deionized water for 3 times, and transferred to a vacuum oven for drying at 80°C for 6 hours to obtain 33.36 grams of high-purity iridium powder with a yield of 95.3%.

[0035] The high-purity iridium powder prepared in Example 5 has a gray-black appearance, no caking or agglomeration, and meets the appearance requirements of the industry for high-purity iridium powder. Figure 1

[0036] Example 6

[0037] A method for preparing high-purity iridium powder, comprising the following steps: (1) Iridium solution preparation: 100 grams of chloro iridic acid is added to 600 grams of deionized water for stirring and dissolution, and an iridium solution A is obtained by filtration to remove insoluble substances;​ (2) Complexing and precipitating iridium: 329.6 g of dipdecyl dimethyl ammonium chloride was added to the iridium solution A, and heated to 90°C, a large amount of yellow precipitate was precipitated, and when the solution changed from orange red to colorless, 171.4 g of iridium-containing precipitate B was obtained by filtration; (3) Recrystallization: 171.4 g of iridium-containing precipitate B was added to deionized water for recrystallization, and 159.1 g of iridium-containing precipitate C was obtained by filtration; (4) Dissolution of iridium-containing precipitate C: 159.1 g of iridium-containing precipitate C was added to 500 g of dilute ammonia water with pH of 8-9 for dissolution, and iridium solution D was obtained and filtered to remove a small amount of insoluble impurities; (5) Reduction to obtain high-purity iridium powder: 55.0 g of hydrazine hydrate was added to the iridium solution D under micro-boiling conditions for stirring reaction, and after the reduction was completed, the iridium powder was obtained by filtration, and after being added to 40 ml of aqua regia and boiled for 1 hour, it was filtered and washed with deionized water for 3 times, and then transferred to a vacuum oven for drying at 80°C for 6 hours to obtain 33.46 g of high-purity iridium powder, with a yield of 95.6%.

[0038] The purity analysis of the high-purity iridium powder prepared in Example 3 is shown in Table 1.

[0039] Table 1: Purity analysis (GDMS) of high-purity iridium powder (μg / kg Ir) Ag 23 Cs <1 Mo <1 Sb <1 Al 35 Cu 38 Na 209 Se <1 As <1 Fe 98 Nb <1 Si 219 Au 58 Ga <1 Ni 83 Sn <1 B <1 Ge <1 Os 16 Sr <1 Ba 6 Hf <1 P <1 Ta <1 Be <1 Hg <1 Pb <1 Te <1 Bi <1 In <1 Pd 89 Th <1 Ca 198 Ir Matrix Pt 335 Ti <1 Cd <1 K 36 Rh 78 Tl <1 Co <1 Li <1 Ru 69 U <1 Cr <1 Mg 18 S <1 Zn 56 The purity analysis of the high-purity iridium powder prepared in Example 6 is shown in Table 2.

[0040] Table 2: Purity analysis (GDMS) of high-purity iridium powder (μg / kg Ir) Ag 58 Cs <1 Mo <1 Sb <1 Al 65 Cu 54 Na 169 Se <1 As <1 Fe 99 Nb <1 Si 229 Au 39 Ga <1 Ni 88 Sn <1 B <1 Ge <1 Os 5 Sr <1 Ba 3 Hf <1 P <1 Ta <1 Be <1 Hg <1 Pb <1 Te <1 Bi <1 In <1 Pd 68 Th <1 Ca 168 Ir Matrix Pt 283 Ti <1 Cd <1 K 36 Rh 56 Tl <1 Co <1 Li <1 Ru 72 U <1 Cr <1 Mg 26 S <1 Zn 61 From Tables 1 and 2, we can see that the content of non-metallic B, S and other element impurities in the high-purity iridium powder prepared by the present application is extremely low, and the content of Ag, Au, Pd, Rh, Ru, Os and other noble metals is also relatively low, indicating that the method disclosed in the present application has very good removal effect on non-metallic impurities and noble metals in chloroiridic acid; since other platinum group metals such as Pt have very similar chemical properties to Ir and are extremely difficult to separate, they must be the focus of attention and research.

[0041] It is apparent to those skilled in the art that the present application is not limited to the details of the foregoing exemplary embodiments, but can be implemented in other concrete forms without departing from the spirit or essential characteristics of the present application. Therefore, the embodiments should be considered in all respects as illustrative and not restrictive, and the scope of the present application is defined by the appended claims rather than the foregoing description, and it is intended to encompass all changes falling within the meaning and scope of equivalents of the claims. Any reference signs in the claims should not be considered as limiting the claims involved.

Claims

1. A method for producing high purity iridium powder, characterized by, The method comprises the following steps: Step 1: dissolving iridium: chloroiridic acid is added to deionized water and stirred to dissolve, and then insoluble substances are removed by filtration to obtain iridium solution A; Step 2: complexing and precipitating iridium: dipdecyl dimethyl ammonium chloride is added to the iridium solution A, and the solution is heated to 80-90 DEG C, a large amount of yellow precipitate is precipitated, and when the solution changes from orange red to colorless, the iridium-containing precipitate B is obtained by filtration; Step 3: recrystallization: the iridium-containing precipitate B is added to deionized water for recrystallization, and the iridium-containing precipitate C is obtained by filtration; Step 4: dissolving the iridium-containing precipitate C to form a solution: the iridium-containing precipitate C is added to dilute ammonia water with a pH of 8-9 and a mass of 5 times that of chloroiridic acid to dissolve, and iridium solution D is obtained and filtered to remove trace amounts of insoluble impurities; Step 5: reducing to obtain high-purity iridium powder: the iridium solution D is added to hydrazine hydrate under micro-boiling conditions, and the mass of the hydrazine hydrate is 4.5-5.5 times that of chloroiridic acid, and the iridium powder is obtained by filtration after reduction, and then the iridium powder is washed with aqua regia, washed with deionized water and vacuum dried to obtain high-purity iridium powder.

2. The method of claim 1, wherein the high purity iridium powder is prepared by the steps of: In step 1, the chloroiridic acid is black needle-shaped crystals, and the iridium content is 35%. ​ 3. The method of producing high purity iridium powder according to claim 1, wherein In step 1, the mass ratio of chloroiridic acid to deionized water is 1:

6.

4. The method of producing high purity iridium powder according to claim 1, wherein In step 2, the dipdecyl dimethyl ammonium chloride is a light yellow transparent liquid, and the purity is >99.5%.

5. The method of producing high purity iridium powder according to claim 1, wherein In step 2, the amount of dipdecyl dimethyl ammonium chloride added is 4-5 times the molar amount of chloroiridic acid.

6. The method of producing high purity iridium powder according to claim 1, wherein In step 4, the dilute ammonia water is electronic grade ammonia water with a mass concentration of 28%.

7. The method of producing high purity iridium powder according to claim 1, wherein In step 5, the hydrazine hydrate is a colorless transparent liquid, and the mass concentration of the high-purity hydrazine hydrate is 80%.

8. The method of producing high purity iridium powder according to claim 1, wherein In step 5, the hydrochloric acid in the aqua regia is electronic grade hydrochloric acid with a mass concentration of 36%, the nitric acid in the aqua regia is electronic grade nitric acid with a mass concentration of 70%, the conductivity of the deionized water should be <0.1 μS / cm, the iridium powder is washed 3 times, and vacuum drying is performed for 6 h.

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