Preparation method of high-purity iridium trichloride

Abstract

The invention relates to the technical field of preparation of iridium trichloride, in particular to a preparation method of high-purity iridium trichloride. Methanol, normal propyl alcohol and the like are added into reaction liquid obtained after ammonium chloroiridate and aqua regia are mixed and dissolved to serve as organic additives for nitrate removal, nitrate reacts with nitrate in the solution to generate gas, and nitrate ions are removed from the solution. Meanwhile, the added organic additives are all alcohol substances which are easy to remove and are extremely easy to volatilize in the subsequent reaction heating process, so that impurities which are difficult to remove cannot be introduced into a reaction system while nitrate is effectively removed, and the purity of a final product can be improved. Organic reducing agents with weak reducibility, such as oxalic acid, citric acid, vitamin C and sulfur dioxide, are used for carrying out reduction reaction, so that iridium powder cannot be separated out in the process of reducing tetravalent iridium, and the purity of trivalent iridium can be ensured. The crystal form of the obtained high-purity iridium trichloride is a beta form, and the purity of the high-purity iridium trichloride is greater than 99.997%.

Description

Technical Field

[0001] The invention relates to the technical field of preparation of iridium trichloride, and in particular to a method for preparing high-purity iridium trichloride. Background Art

[0002] Iridium, a precious metal, has a high melting point and high density. It has the characteristics of good high-temperature mechanical properties, catalytic activity, stable chemical properties, and strong corrosion resistance. Therefore, it has extremely important uses in the fields of aerospace, catalysts, military, weapons, high-energy physics, etc. Iridium chloride is a common compound of iridium, and is often used as the initial raw material for synthesizing other iridium compounds and preparing iridium-containing catalysts. Iridium-containing compounds and catalysts are widely used in the fields of petrochemicals and organic synthesis, hydrogenation catalysts, polymerization catalysts, etc. For example, hydrated iridium trichloride, as the basic raw material for synthesizing iridium complexes, plays an important role in the development of phosphorescent materials. The traditional method for preparing iridium trichloride is to react sponge-like iridium with chlorine in a quartz tube to generate iridium trichloride. However, the IrCl3 obtained by this method is insoluble in water, acid, and alkali, and is inconvenient to be widely used in industry.

[0003] For example, patent CN 106854001A discloses a controlled reduction preparation method of iridium trichloride, wherein tetravalent iridium chloride and a reducing agent are added to a three-necked flask in a certain proportion, and the tetravalent iridium in the solution is reduced at a constant temperature under magnetic stirring conditions until all the tetravalent iridium in the solution is converted to trivalent iridium. A condensation reflux device is used in the reaction process to reduce the volatilization of the reducing agent and control the stability of the reaction system to control the purity of iridium trichloride. However, this method does not carry out the nitrate removal treatment, and the final product is mixed with many impurities, and the product purity is not high.

[0004] Invention CN 114105229A This application discloses a method for preparing high-purity iridium trichloride, using iridium powder as a raw material and alkali melting through the mixed action of sodium peroxide, sodium hydroxide and sodium carbonate; the alkali-melted solid is dissolved with aqua regia, and the filtered solution is added with ammonium chloride to form precipitated ammonium chloroiridate, and the ammonium chloroiridate is reacted with hydrazine hydrochloride to form ammonium chloroiridate, and then further impurities are removed by sodium sulfide and ammonium sulfide and filtered, and the filtrate is oxidized by hydrochloric acid / hydrogen peroxide and precipitated by ammonium chloride solution to obtain ammonium chloroiridate with higher purity; after the ammonium chloroiridate is driven out of nitrate with aqua regia solution, the obtained chloroiridic acid solution is added with sodium nitrite / potassium chloride and boiled to obtain potassium hexanitrosoiridate solid, and the solid is added with hydrochloric acid to boil and dissolve after filtering, and after the nitrate is driven out, an appropriate amount of hydrazine hydrochloride is added, and the solution is subjected to rotary evaporation and vacuum calcination to obtain iridium trichloride solid with a purity greater than 99.995%. However, this method has the disadvantages of long nitrate driving process, high energy consumption, large acid consumption and environmental pollution. Summary of the invention

[0005] In view of the problems existing in the prior art, the present invention provides a method for preparing high-purity iridium trichloride, which specifically comprises the following steps:

[0006] A method for preparing high-purity iridium trichloride comprises the following steps:

[0007] S1, dissolving: mixing ammonium chloroiridate and aqua regia in a volume ratio of 1:(1-5), and dissolving at 80-120° C. to obtain a mixed solution;

[0008] S2, driving out the nitrate: adding organic additives to the mixed solution in batches until no bubbles are generated in the mixed solution; the organic additives are one or more of ethanol, methanol, n-propanol, propylene alcohol, ethylene glycol, propylene glycol, and glycerol;

[0009] S3, reduction: adding the same organic additive as in step S2 to the mixed solution after removing the nitrate, and then heating to 60-120°C for reaction until the reaction solution turns dark green;

[0010] S4, post-treatment: post-treating the reduced reaction solution to obtain the high-purity iridium trichloride.

[0011] Furthermore, the mixing method of the ammonium chloroiridate and aqua regia in step S1 is: firstly adding concentrated hydrochloric acid to the ammonium chloroiridate to make it slurry, and then adding concentrated nitric acid to completely dissolve the ammonium chloroiridate.

[0012] Furthermore, in step S1, the mass ratio of the ammonium chloroiridate to aqua regia is controlled to be 1:(1-10).

[0013] Furthermore, in step S2, the mass ratio of ammonium chloroiridate to the organic additive in the reaction system is controlled to be 1:(10-20).

[0014] Furthermore, the reduction reaction time in step S3 is 2-8 hours.

[0015] Furthermore, the post-processing in step S4 includes:

[0016] a. The reaction solution after the reduction is concentrated and crystallized to obtain slurry of iridium trichloride;

[0017] b. drying the slurry iridium trichloride to obtain the high-purity iridium trichloride.

[0018] Furthermore, the drying temperature is less than 80°C.

[0019] Furthermore, the crystal form of the high-purity iridium trichloride is β-type and the purity is greater than 99.997%.

[0020] Furthermore, the mass of iridium in the high-purity iridium trichloride obtained in step S4 accounts for more than 99% of the mass of iridium in the ammonium chloroiridate used in step S1, that is, the recovery rate of iridium by the method of the present invention is greater than 99%.

[0021] Beneficial effects of the present invention:

[0022] (1) The present invention adds one or more of methanol, n-propanol, propenol, ethylene glycol, propylene glycol, and glycerol as organic additives to the reaction solution after ammonium chloroiridate and aqua regia are mixed and dissolved to drive out nitrate. The organic additives react with nitrate ions in the solution to generate gas, so that nitrate ions are driven out of the solution. At the same time, the added organic additives are all alcohol substances that are easy to remove and are very volatile in the subsequent reaction heating process. Therefore, while effectively driving out nitrate, impurities that are difficult to remove will not be introduced into the reaction system, which can improve the purity of the final product.

[0023] (2) The preparation method of high-purity iridium trichloride disclosed in the present invention uses a weakly reducing organic reducing agent such as methanol, n-propanol, propylene alcohol, ethylene glycol, propylene glycol, and glycerol for reduction reaction, which neither precipitates iridium powder during the reduction of tetravalent iridium nor guarantees the purity of trivalent iridium. The present invention compares the selection of additives in the reaction process and improves the process flow and process parameters. The crystal form of the high-purity iridium trichloride finally prepared is β-type and the purity is greater than 99.997%, which can meet the needs of industrial production. At the same time, the recovery rate of iridium is greater than 99% by using the method of the present invention, which can effectively avoid the waste of iridium. BRIEF DESCRIPTION OF THE DRAWINGS

[0024] Figure 1 The present invention is a schematic diagram of the process flow of the method disclosed in the present invention. DETAILED DESCRIPTION

[0025] The present invention is described in detail below in conjunction with the accompanying drawings and specific embodiments. The embodiments shown below do not limit the invention content described in the claims. In addition, the entire contents of the structures represented by the following embodiments are not limited to those necessary as solutions to the invention described in the claims.

[0026] Reference Figure 1 , a method for preparing high-purity iridium trichloride, comprising the following steps:

[0027] S1, dissolving: ammonium chloroiridate and aqua regia (a mixture of concentrated hydrochloric acid and concentrated nitric acid) are mixed in a volume ratio of 1:(1-5), wherein the specific mixing method is: firstly, concentrated hydrochloric acid is added to the ammonium chloroiridate to make a slurry, and then concentrated nitric acid is added to completely dissolve the ammonium chloroiridate, the dissolving temperature is controlled at 80-120° C., and the mass ratio of the ammonium chloroiridate to the aqua regia is controlled at 1:(1-10), to obtain a mixed solution;

[0028] S2, driving out the nitrate: adding organic additives to the mixed solution in batches until no bubbles are generated in the mixed solution (the organic additives may be appropriately excessive), and controlling the mass ratio of ammonium chloroiridate in the reaction system to the organic additives to be 1:(10-20); the organic additives are one or more of methanol, n-propanol, propylene alcohol, ethylene glycol, propylene glycol, and glycerol;

[0029] S3, reduction: adding the organic additive to the mixed solution after removing the nitrate, and then heating to 60-120° C. for reaction for 2-8 hours until the reaction solution turns dark green;

[0030] S4, post-treatment: the reaction solution after reduction is concentrated and crystallized to obtain slurry iridium trichloride; the slurry iridium trichloride is dried at a temperature of less than 80°C to obtain the high-purity iridium trichloride, the crystal form of the high-purity iridium trichloride is β-type and the purity is greater than 99.997%. Moreover, the mass of iridium in the high-purity iridium trichloride finally obtained accounts for more than 99% of the mass of iridium in the ammonium chloroiridate used in step S1, that is, the recovery rate of iridium by the method of the present invention is greater than 99%.

[0031] Example 1

[0032] A method for preparing high-purity iridium trichloride comprises the following steps:

[0033] S1, dissolving: ammonium chloroiridate and aqua regia (a mixture of concentrated hydrochloric acid and concentrated nitric acid) are mixed in a volume ratio of 1:1.2, and the specific mixing method is: firstly, concentrated hydrochloric acid is added to the ammonium chloroiridate to make a slurry, and then concentrated nitric acid is added to completely dissolve the ammonium chloroiridate, and the dissolving temperature is controlled at 80° C. to obtain a mixed solution;

[0034] S2, driving out nitrate: adding methanol to the mixed solution in batches until no bubbles are generated in the mixed solution, and controlling the mass ratio of ammonium chloroiridate to methanol in the reaction system to be 1:15;

[0035] S3, reduction: adding methanol to the mixed solution after removing the nitrate, and then heating to 60-120°C for reaction for 2-8 hours until the reaction solution turns dark green;

[0036] S4, post-treatment: concentrating and crystallizing the reduced reaction solution to obtain slurry iridium trichloride; drying the slurry iridium trichloride at 78° C. to obtain high-purity iridium trichloride.

[0037] After testing, the high-purity iridium trichloride obtained in this embodiment has a β-type crystal form and a purity of 99.998%. The recovery rate of iridium in this embodiment is 99.3%.

[0038] Example 2

[0039] A method for preparing high-purity iridium trichloride comprises the following steps:

[0040] S1, dissolving: ammonium chloroiridate and aqua regia (a mixture of concentrated hydrochloric acid and concentrated nitric acid) are mixed in a volume ratio of 1:5, and the specific mixing method is: firstly, concentrated hydrochloric acid is added to the ammonium chloroiridate to make a slurry, and then concentrated nitric acid is added to completely dissolve the ammonium chloroiridate, the dissolving temperature is controlled at 120° C., and the mass ratio of the ammonium chloroiridate to the aqua regia is controlled to be 1:10, to obtain a mixed solution;

[0041] S2, driving out nitrate: adding glycerol to the mixed solution in batches until no bubbles are generated in the mixed solution, and controlling the mass ratio of ammonium chloroiridate to the organic additive in the reaction system to be 1:11;

[0042] S3, reduction: add glycerol to the mixed solution after removing the nitrate, and then heat it to 120°C for reaction for 8 hours until the reaction solution turns dark green;

[0043] S4, post-treatment: concentrating and crystallizing the reduced reaction solution to obtain slurry iridium trichloride; drying the slurry iridium trichloride at 60° C. to obtain high-purity iridium trichloride.

[0044] After testing, the high-purity iridium trichloride obtained in this embodiment has a β-type crystal form and a purity of 99.998%. The recovery rate of iridium in this embodiment is 99.5%.

[0045] Example 3

[0046] A method for preparing high-purity iridium trichloride comprises the following steps:

[0047] S1, dissolving: ammonium chloroiridate and aqua regia (a mixture of concentrated hydrochloric acid and concentrated nitric acid) are mixed in a volume ratio of 1:4, and the specific mixing method is: firstly, concentrated hydrochloric acid is added to the ammonium chloroiridate to make a slurry, and then concentrated nitric acid is added to completely dissolve the ammonium chloroiridate, the dissolving temperature is controlled at 100° C., and the mass ratio of the ammonium chloroiridate to the aqua regia is controlled to be 1:6, to obtain a mixed solution;

[0048] S2, driving away the nitrate: adding ethylene glycol to the mixed solution in batches until no bubbles are generated in the mixed solution (ethylene glycol may be appropriately excessive), and controlling the mass ratio of ammonium chloroiridate to the organic additive in the reaction system to be 1:10;

[0049] S3, reduction: adding ethylene glycol to the mixed solution after removing the nitrate, and then heating to 100°C for reaction for 5 hours until the reaction solution turns dark green;

[0050] S4, post-treatment: concentrating and crystallizing the reduced reaction solution to obtain slurry iridium trichloride; drying the slurry iridium trichloride at 50° C. to obtain high-purity iridium trichloride.

[0051] After testing, the crystal form of the high-purity iridium trichloride is β-type and the purity is 99.999%. In addition, the recovery rate of iridium in this embodiment is 99.7%.

[0052] Example 4

[0053] A method for preparing high-purity iridium trichloride comprises the following steps:

[0054] S1. Weigh 10 g of ammonium chloroiridate and dissolve it in aqua regia (hydrochloric acid: nitric acid) at a volume ratio of 1:1 in an 80°C oil bath. The mass ratio of ammonium chloroiridate to aqua regia is 1:4.

[0055] S2, after the ammonium chloroiridate is completely dissolved, add excess additive (propylene glycol) thereto, visually observe that no yellow smoke is released from the solution, add in batches, and continue to add until no bubbles are generated, indicating that the nitrate is completely removed. The mass ratio of ammonium chloroiridate to the additive is 1:10.

[0056] S3, then continue to add a certain amount of the above additives to the chloroiridic acid solution after the nitrate is removed, react at 60°C for 2 hours to ensure that the additives added are excessive, observe the color change of the solution, and stop the reaction when the solution changes from reddish brown to dark green.

[0057] S4, after the reaction is completed, the solution is concentrated to a slurry state and then transferred to a culture dish. The slurry of iridium trichloride is dried by an infrared lamp to obtain 13.4g of high-purity IrCl3.

[0058] After testing, the high-purity iridium trichloride has a β-type crystal form and a purity of 99.998%.

[0059] Example 5

[0060] A method for preparing high-purity iridium trichloride comprises the following steps:

[0061] S1. Weigh 15 g of ammonium chloroiridate and dissolve it in a 100° C. oil bath with aqua regia (hydrochloric acid: nitric acid) at a volume ratio of 1:3. The mass ratio of ammonium chloroiridate to aqua regia is 1:6.

[0062] S2, after the ammonium chloroiridate is completely dissolved, add excess additive (propylene alcohol) thereto, visually observe that no yellow smoke is released from the solution, add in batches, and continue to add until no bubbles are generated, indicating that the nitrate is completely removed. The mass ratio of ammonium chloroiridate to the additive is 1:15.

[0063] S3, then continue to add a certain amount of the above additives to the chloroiridic acid solution after the nitrate is removed, react at 90°C for 4 hours to ensure that the additives added are excessive, observe the color change of the solution, and stop the reaction when the solution changes from reddish brown to dark green.

[0064] S4, after the reaction is completed, the solution is concentrated to a slurry state and then transferred to a culture dish. The slurry of iridium trichloride is dried by an infrared lamp to obtain 18.5g of high-purity IrCl3.

[0065] After testing, the high-purity iridium trichloride has a β-type crystal form and a purity of 99.999%.

[0066] Example 6

[0067] A method for preparing high-purity iridium trichloride comprises the following steps:

[0068] S1, weigh 20g of ammonium chloroiridate, dissolve it in a 120°C oil bath with aqua regia (hydrochloric acid: nitric acid) at a volume ratio of 1:5, and the mass ratio of ammonium chloroiridate to aqua regia is 1:8.

[0069] S2, after the ammonium chloroiridate is completely dissolved, add excess additive (propylene alcohol) thereto, visually observe that no yellow smoke is released from the solution, add in batches, and continue to add until no bubbles are generated, indicating that the nitrate is completely removed. The mass ratio of ammonium chloroiridate to the additive is 1:20.

[0070] S3, then continue to add a certain amount of the above additives to the chloroiridic acid solution after the nitrate is removed, react at 120°C for 8 hours, ensure that the added additives are excessive, observe the color change of the solution, and stop the reaction when the solution changes from reddish brown to dark green.

[0071] S4, after the reaction is completed, the solution is concentrated to a slurry state and then transferred to a culture dish. The slurry of iridium trichloride is dried by an infrared lamp to obtain 23.6g of high-purity IrCl3.

[0072] After testing, the high-purity iridium trichloride has a β-type crystal form and a purity of 99.998%.

[0073] Comparative Example 1

[0074] The difference between this comparative example and Example 1 is that aqua regia is used to remove nitrate, and other conditions are the same.

[0075] After testing, the purity of the iridium trichloride prepared in this comparative example is 99.91%.

[0076] Comparative Example 2

[0077] The difference between this comparative example and Example 1 is that hydrazine hydrochloride is used as the reducing agent, and other conditions are the same.

[0078] After testing, the purity of the iridium trichloride prepared in this comparative example is 99.97%.

[0079] The above description of the disclosed embodiments enables one skilled in the art to implement or use the present invention. Various modifications to these embodiments will be apparent to one skilled in the art, and the general principles defined herein may be implemented in other embodiments without departing from the spirit or scope of the present invention. Therefore, the present invention will not be limited to the embodiments shown herein, but rather to the widest scope consistent with the principles and novel features disclosed herein.

Claims

1. A method for preparing high-purity iridium trichloride, characterized in that, The following steps are involved: S1, dissolving: mixing ammonium chloroiridate and aqua regia in a volume ratio of 1:(1-5), and dissolving at 80-120° C. to obtain a mixed solution; S2, driving out the nitrate: adding organic additives to the mixed solution in batches until no bubbles are generated in the mixed solution; the organic additives are one or more of methanol, n-propanol, ethanol, propylene alcohol, ethylene glycol, propylene glycol, and glycerol; S3, reduction: adding the same organic additive as in step S2 to the mixed solution after removing the nitrate, and then heating to 60-120°C for reaction until the reaction solution turns dark green; S4, post-treatment: post-treating the reduced reaction solution to obtain the high-purity iridium trichloride.

2. A method for preparing high-purity iridium trichloride according to claim 1, characterized in that: The mixing method of the ammonium chloroiridate and aqua regia in step S1 is: firstly add concentrated hydrochloric acid to the ammonium chloroiridate to make it slurry, and then add concentrated nitric acid to completely dissolve the ammonium chloroiridate.

3. A method for preparing high-purity iridium trichloride according to claim 1, characterized in that: Step S1 controls the mass ratio of the ammonium chloroiridate to aqua regia to be 1:(1-10).

4. A method for preparing high-purity iridium trichloride according to claim 1, characterized in that: Step S2 controls the mass ratio of ammonium chloroiridate to the organic additive in the reaction system to be 1:(10-20).

5. A method for preparing high-purity iridium trichloride according to claim 1, characterized in that: The reduction reaction time in step S3 is 2-8 hours.

6. A method for preparing high-purity iridium trichloride according to claim 1, characterized in that: The post-processing in step S4 includes: a. The reaction solution after the reduction is concentrated and crystallized to obtain slurry of iridium trichloride; b. drying the slurry iridium trichloride to obtain the high-purity iridium trichloride.

7. A method for preparing high-purity iridium trichloride according to claim 6, characterized in that: The drying temperature is less than 80°C.

8. The method for preparing high-purity iridium trichloride according to any one of claims 1 to 7, characterized in that: The high-purity iridium trichloride has a β-type crystal form and a purity greater than 99.997%.

9. A method for preparing high-purity iridium trichloride according to claim 8, characterized in that: The mass of iridium in the high-purity iridium trichloride obtained in step S4 accounts for more than 99% of the mass of iridium in the ammonium chloroiridate used in step S1.

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