Synthesis method of high-purity chloroiridic acid

Abstract

The invention relates to a synthetic method of high-purity chloroiridic acid. The synthetic method comprises the following specific operation steps: S1, pretreating an iridium source containing iridium metal; s2, reacting the pretreated iridium source with chlorine in a reaction kettle to generate a chloroiridic acid solution; s3, purifying the chloroiridic acid solution to obtain a chloroiridic acid crystal; and S4, washing and drying the chloroiridic acid crystal to obtain a chloroiridic acid product. The catalyst is adopted to catalyze the reaction of the iridium powder and the chlorine, so that the generation rate and the purity of the chloroiridic acid are improved, and the yield of the chloroiridic acid is improved; the acid solution is used as a solvent of the iridium compound, so that the solubility of the iridium compound is improved, the reaction time is shortened, and the energy consumption is reduced; chloroiridic acid crystals are treated by adopting the steps of washing, drying and the like, so that the purity and the stability of chloroiridic acid products are improved.

Description

TECHNICAL FIELD

[0001] The application belongs to the technical field of noble metal compound preparation, and relates to a production and preparation process of high-purity chloro iridic acid, in particular to a synthesis method of high-purity chloro iridic acid. BACKGROUND

[0002] Iridium is a rare transition metal element with high chemical stability and catalytic activity. Iridium compounds have wide application prospects in petroleum chemical industry, medicine, environmental protection and other fields. Chloro iridic acid is an important noble metal compound, which has wide application in electronics, chemical industry, catalysis and other fields. However, the traditional chloro iridic acid preparation process has some problems, such as low purity, low production efficiency, high cost, environmental pollution and the like. With the rapid development of high-end electronics, chemical industry and other fields, the demand for high-purity chloro iridic acid is increasing. Therefore, it is of great practical significance to develop an efficient, low-cost and high-purity chloro iridic acid production and preparation process.

[0003] At present, the production of chloro iridic acid mainly adopts two methods of chlorination method and oxidation method. The chlorination method is to react iridium powder with chlorine to generate chloro iridic acid, and then to obtain chloro iridic acid product through distillation, crystallization and other steps. Chinese patent CN108455688A discloses a rapid preparation method of chloro iridic acid. The method is as follows: first, iridium powder and hydrochloric acid are added into a reaction kettle, chlorine is introduced into the reaction kettle to react under certain conditions, after the reaction is completed, concentrated hydrochloric acid is added into the reaction kettle to remove the free chlorine in the reaction liquid, after the chlorine is removed, the filtrate and the filter residue are obtained by filtration, the filtrate contains trivalent iridium and tetravalent iridium, then the filtrate is used as raw material to react with nitric acid to oxidize the trivalent iridium in the filtrate to tetravalent iridium, to obtain chloro iridic acid solution, and finally the chloro iridic acid solution is concentrated to obtain chloro iridic acid product. The advantage of this method is fast reaction speed and high production efficiency, but it also has some problems. First, chlorine is a toxic and harmful gas, its leakage will cause serious harm to the environment and human health. Second, the distillation and crystallization process in the chlorination method consumes a large amount of energy and has a certain impact on the environment.

[0004] The oxidation method is to react iridium powder with oxygen to generate iridium oxide, and then to obtain chloro iridic acid by reduction with a reducing agent. The advantage of this method is that the reaction conditions are mild and no toxic and harmful chemicals are used, but there are also some problems. First, the selection and use of the reducing agent in the oxidation method are complex, and factors such as activity, stability and safety of the reducing agent need to be considered. Second, by-products may be produced in the reduction process, which may affect the purity and quality of chloro iridic acid.

[0005] Therefore, it is necessary to improve the existing chloro iridic acid production process to improve production efficiency, reduce energy consumption, and improve product purity and yield. SUMMARY

[0006] The application aims to provide a synthesis method of high-purity chloroiridic acid to solve the problems of low purity, low production efficiency, high cost and environmental pollution in traditional processes.

[0007] To achieve the above-mentioned purpose, the application adopts the following technical solutions:

[0008] A synthesis method of high-purity chloroiridic acid, the specific operation steps are as follows:

[0009] S1, pretreating an iridium source containing iridium metal;

[0010] S2, reacting the pretreated iridium source with chlorine in a reaction kettle to generate a chloroiridic acid solution;

[0011] S3, purifying the chloroiridic acid solution to obtain a chloroiridic acid crystal;

[0012] S4, washing and drying the chloroiridic acid crystal to obtain a chloroiridic acid product.

[0013] Preferably, the iridium source in step S1 includes iridium powder, iridium ore and iridium-containing waste;

[0014] Preferably, the pretreatment in step S1 includes S11 ball milling treatment of the iridium source to make the particle size less than 50 μm.

[0015] Preferably, the pretreatment in step S1 further includes S12 acid pickling and water washing method for purifying the iridium source to remove impurities; the acid pickling step in step S12 is to put the iridium source into a dilute hydrochloric acid solution with a mass concentration of 5-20%, and soak for 2 h;

[0016] The water washing step in step S12 is to put the acid-pickled iridium source into high-purity water and repeatedly rinse until the water is neutral;

[0017] After water washing in step S12, filtering and drying, the specific operation of drying is to put the iridium source into an oven at 85°C for 2 h.

[0018] Preferably, the volume purity of chlorine in step S2 is 99.0%-99.99%;

[0019] The reaction kettle in step S2 is a concentrated hydrochloric acid environment, and the mass concentration of the concentrated hydrochloric acid is 38%;

[0020] The mass ratio of the iridium source to chlorine and hydrochloric acid in step S2 is 1:(3-5):6.

[0021] Preferably, the temperature of the reaction kettle in step S2 is 100-200°C; and the reaction time in step S2 is 5-8 h.

[0022] Preferably, the pressure of the reaction kettle in step S2 is 0.1-0.6 MPa.

[0023] Preferably, the purification method in step S3 comprises filtering, purifying, and crystallizing.

[0024] The purifying step purifies the filtered chloroiridic acid solution by ion exchange resin column, and the strong acid cation exchange resin is selected, the exchange capacity of the resin is 4.5 mmol / g, the flow rate of the solution is 10 mL / min, and the number of times of passing through the ion exchange resin column is 2-6 times.

[0025] The crystallizing step concentrates the purified chloroiridic acid solution, concentrates the solution until solid is precipitated, then cools the concentrated solution to 10℃, and stirs at the temperature for 4 h to make chloroiridic acid crystallize and precipitate.

[0026] Preferably, the washing method in step S4 is that anhydrous ethanol at 0-10℃ is slowly flushed on the surface of the crystal, and the flushing is repeated for 2-3 times.

[0027] Preferably, the drying temperature in step S4 is 40-50℃, and the maintaining time is 2-3 h.

[0028] The beneficial effects of the present application are as follows:

[0029] 1. The present application uses a catalyst to catalyze the reaction of iridium powder and chlorine, which improves the generation rate and purity of chloroiridic acid, thereby improving the yield of chloroiridic acid.

[0030] 2. The present application uses an acidic solution as a solvent for iridium compounds, which improves the solubility of iridium compounds, shortens the reaction time, and reduces energy consumption.

[0031] 3. The present application uses washing, drying, and other steps to process chloroiridic acid crystals, which improves the purity and stability of chloroiridic acid products.

[0032] 4. The method of the present application is simple to operate, mild in conditions, and low in equipment requirements, which is suitable for industrial production. DETAILED DESCRIPTION

[0033] The technical solutions of the present application will be described clearly and completely in combination with the embodiments of the present application, and the described embodiments are only a part of the embodiments of the present application, rather than all. Based on the embodiments of the present application, other embodiments obtained by other persons in the art without creative labor are within the protection scope of the present application.

[0034] Wherein, the method is a conventional method if not specially stated, and the raw material can be obtained from public commercial channels if not specially stated.

[0035] Example 1

[0036] Raw material pretreatment ball milling: 100 g of iridium powder was placed in a ball mill for ball milling treatment, the rotation speed of the ball mill was 500 r / min, and the ball milling time was 4 h. The particle size of the milled iridium powder was less than 50 μm.

[0037] Purification treatment: the milled iridium powder was placed in an acid pickling tank, and 15% dilute hydrochloric acid was added for acid pickling treatment, and the acid pickling time was 2 h. Then the acid-pickled iridium powder was taken out, washed with high-purity water until the pH value of the washing water was neutral, and then the iridium powder was collected by filtration, and placed in an oven at 85°C for 2 h.

[0038] Reaction process

[0039] Reaction material ratio: the pretreated iridium powder, chlorine gas and hydrochloric acid were added into the reaction kettle according to the molar ratio of 1:3:6, and the mass concentration of hydrochloric acid was 38%.

[0040] Reaction condition control: the reaction kettle was heated to 150°C, and chlorine gas was introduced to make the pressure in the reaction kettle reach 0.5 MPa. The reaction was carried out at this temperature and pressure for 5 h.

[0041] Purification step multi-stage filtration: the reaction product was filtered through a coarse filter to remove larger particle impurities. Then the filtrate was filtered through a precision filter to remove fine particle impurities.

[0042] Ion exchange resin purification: the filtered chloroiridic acid solution was purified by ion exchange resin column. Strong acid cation exchange resin was selected, and the exchange capacity of the resin was 4.5 mmol / g. The flow rate of the solution was 10 mL / min, and the number of times of passing through the ion exchange resin column was 3.

[0043] Crystallization purification: the purified chloroiridic acid solution was concentrated to make solid precipitate. Then the concentrated solution was slowly cooled to 10°C, and stirred at this temperature for 4 h to make chloroiridic acid crystallize. The crystallized chloroiridic acid crystals were washed and dried to obtain high-purity chloroiridic acid product. 10°C anhydrous ethanol was slowly flushed on the surface of the crystals, and the flushing was repeated twice. The drying temperature was 40°C, and the drying time was 2 h.

[0044] Tail gas treatment

[0045] Absorption tower design: two-stage absorption tower is used to treat the tail gas generated in the reaction process. The first-stage absorption tower uses water as the absorbent to absorb chlorine in the tail gas; the second-stage absorption tower uses sodium hydroxide solution as the absorbent to absorb hydrochloric acid in the tail gas. Absorbent recycling: the absorbed chlorine and hydrochloric acid solution are treated respectively to recover chlorine and hydrochloric acid. In this embodiment, chloroiridic acid with an iridium content of 39.97% is prepared, and the direct recovery rate of iridium is greater than 99%. The product quality of chloroiridic acid meets the requirements of the YS / T 595-2022 chloroiridic acid industry standard.

[0046] Example 2

[0047] Raw material pretreatment ball milling: 100 g of iridium powder is put into a ball mill for ball milling treatment, the rotation speed of the ball mill is 600 r / min, and the ball milling time is 4 h. The particle size of the ball-milled iridium powder is less than 40 μm.

[0048] Purification treatment: the ball-milled iridium powder is put into an acid pickling tank, and 20% dilute hydrochloric acid is added for acid pickling treatment, and the acid pickling time is 2 h. Then the acid-pickled iridium powder is taken out, washed with high-purity water until the pH value of the washing water is neutral, and then the iridium powder is collected by filtration, and the iridium powder is placed in an oven at 85°C for 2 h.

[0049] Reaction process

[0050] Reaction material ratio: the pretreated iridium powder, chlorine and hydrochloric acid are added into the reaction kettle according to the molar ratio of 1:4:6, and the mass concentration of hydrochloric acid is 38%.

[0051] Reaction condition control: the reaction kettle is heated to 100°C, and chlorine is introduced to make the pressure in the reaction kettle reach 0.6 MPa. Under this temperature and pressure, the reaction is carried out for 7 h.

[0052] Purification step multi-stage filtration: the reaction product is filtered through a coarse filter to remove larger particle impurities. Then the filtrate is filtered through a precision filter to remove fine particle impurities.

[0053] Ion exchange resin purification: the filtered chloroiridic acid solution is purified through an ion exchange resin column. Strong acid cation exchange resin is selected, and the exchange capacity of the resin is 5.0 mmol / g. The flow rate of the solution is 10 mL / min, and the number of times of passing through the ion exchange resin column is 4.

[0054] Crystallization purification: The purified chloroiridic acid solution is concentrated to allow solid to precipitate. Then the concentrated solution is slowly cooled to 10℃ and stirred at this temperature for 5h to allow chloroiridic acid to crystallize and precipitate. The crystallized chloroiridic acid crystals are washed and dried to obtain high-purity chloroiridic acid product. The crystal surface is slowly flushed with anhydrous ethanol at 0℃, repeated for 3 times, and the drying temperature is 50℃ for 3h.

[0055] Tail gas treatment

[0056] Absorption tower design: Two-stage absorption tower and nitrogen purging are used to treat the tail gas generated during the reaction. Water is used as the absorbent in the first-stage absorption tower to absorb chlorine in the tail gas; sodium hydroxide solution is used as the absorbent in the second-stage absorption tower to absorb hydrochloric acid in the tail gas.

[0057] Absorbent recycling: The absorbed chlorine and hydrochloric acid solution are treated separately to recover chlorine and hydrochloric acid. In this embodiment, 246.95g of chloroiridic acid with an iridium content of 40.13% is prepared, and the direct recovery rate of iridium is greater than 99%. The product quality of chloroiridic acid meets the requirements of YS / T 595-2022 industry standard for chloroiridic acid.

[0058] The production and preparation process of high-purity chloroiridic acid is optimized, which significantly improves the purity and production efficiency of chloroiridic acid, reduces production cost, and reduces environmental pollution. The process has the advantages of simple operation, low cost, high efficiency, environmental friendliness, etc., and is suitable for large-scale industrial production.

[0059] Example 3

[0060] Raw material pretreatment ball milling: 500g of iridium powder is put into a ball mill for ball milling, the rotation speed of the ball mill is 500r / min, and the ball milling time is 4h. The particle size of the milled iridium powder is less than 50μm.

[0061] Purification treatment: The milled iridium powder is put into an acid washing tank, and 18% dilute hydrochloric acid is added for acid washing treatment, and the acid washing time is 2h. Then the acid washed iridium powder is taken out, washed with high-purity water until the pH value of the washing water is neutral, then the iridium powder is collected by filtration, and the iridium powder is placed in an oven at 85℃ for 2h.

[0062] Reaction process

[0063] Reaction material ratio: The pretreated iridium powder, chlorine and hydrochloric acid are added into the reaction kettle according to the molar ratio of 1:5:6, and the mass concentration of hydrochloric acid is 38%.

[0064] Reaction condition control: The reaction kettle is heated to 200℃ and chlorine is introduced to make the pressure in the reaction kettle reach 0.1MPa. The reaction is carried out at this temperature and pressure for 8h.

[0065] Purification step multi-stage filtration: the reaction product is filtered through a coarse filter to remove larger particulate impurities. The filtrate is then filtered through a precision filter to remove fine particulate impurities.

[0066] Ion exchange resin purification: the filtered chloroiridic acid solution is purified through an ion exchange resin column. A strong acid cation exchange resin is selected, with an exchange capacity of 4.5 mmol / g. The flow rate of the solution is 10 mL / min, and the solution is passed through the ion exchange resin column 3 times.

[0067] Crystallization purification: the purified chloroiridic acid solution is concentrated to allow solid to precipitate. The concentrated solution is then slowly cooled to 10℃ and stirred at this temperature for 5 h to allow chloroiridic acid to crystallize. The crystallized chloroiridic acid crystals are washed and dried to obtain high-purity chloroiridic acid product. The crystal surface is slowly rinsed with anhydrous ethanol at 5℃, repeated 2 times, and the drying temperature is 45℃ for 2.5 h.

[0068] Tail gas treatment

[0069] Absorption tower design: a two-stage absorption tower and nitrogen purging method is used to treat the tail gas generated during the reaction. The first-stage absorption tower uses water as the absorbent to absorb chlorine gas in the tail gas; the second-stage absorption tower uses sodium hydroxide solution as the absorbent to absorb hydrochloric acid in the tail gas.

[0070] Absorbent recycling: the absorbed chlorine gas and hydrochloric acid solution are treated separately to recover the chlorine gas and hydrochloric acid.

[0071] In this example, chloroiridic acid 1239.4 g with an iridium content of 40.06% was prepared, and the direct recovery rate of iridium was greater than 99%. The product quality of chloroiridic acid was detected to meet the requirements of the YS / T 595-2022 chloroiridic acid industry standard.

[0072] Comparative Example 1

[0073] The difference between this comparative example and Example 1 is that the reaction conditions are controlled: the reaction kettle is heated to 150℃ and chlorine gas is introduced to make the pressure in the reaction kettle reach 0.03 MPa. The reaction is carried out at this temperature and pressure for 5 h.

[0074] In this example, chloroiridic acid 217.76 g with an iridium content of 40.09% was prepared, and the direct recovery rate of iridium was 87.3%.

[0075] From the comparison of Comparative Example 1 and Example 1, it can be seen that the pressure in the reaction kettle is less than 0.1 MPa, and the direct recovery rate of iridium decreases.

[0076] Comparative Example 2

[0077] The difference between this comparative example and Example 1 is that the reaction condition control: the reaction kettle is heated to 150°C, and chlorine is introduced to make the pressure in the reaction kettle reach 0.8 MPa. The reaction is carried out at this temperature and pressure for 5 h.

[0078] This example produces chloroiridic acid with an iridium content of 40.01%, 222.94 g, and an iridium direct yield of 89.2%.

[0079] From the comparison of Comparative Example 2 and Example 1, it can be seen that the pressure in the reaction kettle is greater than 0.6 MPa, and the direct yield of iridium is reduced.

[0080] Comparative Example 3

[0081] Raw material pretreatment ball milling: 100 g of iridium powder is put into a ball mill for ball milling, the rotation speed of the ball mill is 500 r / min, and the ball milling time is 4 h. The particle size of the milled iridium powder is less than 50 μm.

[0082] Reaction process

[0083] Reaction material ratio: the pretreated iridium powder, chlorine and hydrochloric acid are added into the reaction kettle according to the molar ratio of 1:3:6. Reaction condition control: the reaction kettle is heated to 150°C, and chlorine is introduced to make the pressure in the reaction kettle reach 0.5 MPa. The reaction is carried out at this temperature and pressure for 5 h.

[0084] Purification step multi-stage filtration: the reaction product is filtered through a coarse filter to remove larger particle impurities. Then the filtrate is filtered through a precision filter to remove fine particle impurities.

[0085] Ion exchange resin purification: the filtered chloroiridic acid solution is purified through an ion exchange resin column. A strong acid cation exchange resin is selected, and the exchange capacity of the resin is 4.5 mmol / g. The flow rate of the solution is 10 mL / min, and the number of times the solution passes through the ion exchange resin column is 3.

[0086] Crystallization purification: the purified chloroiridic acid solution is concentrated to make solid precipitate. Then the concentrated solution is slowly cooled to 10°C, and stirred at this temperature for 4 h to make chloroiridic acid crystallize. The crystallized chloroiridic acid crystals are washed and dried to obtain high-purity chloroiridic acid product. The crystal surface is slowly washed with anhydrous ethanol at 10°C, and the washing is repeated twice. The drying temperature is 40°C, and the drying is maintained for 2 h.

[0087] Tail gas treatment

[0088] The absorption tower design: two-stage absorption tower is used to treat the tail gas produced in the reaction process. The first-stage absorption tower uses water as the absorbent to absorb chlorine in the tail gas; the second-stage absorption tower uses sodium hydroxide solution as the absorbent to absorb hydrochloric acid in the tail gas. The absorbent is recycled: the absorbed chlorine and hydrochloric acid solution are treated respectively to recover the chlorine and hydrochloric acid. In this embodiment, chloroiridic acid 217.72 g with the iridium content of 39.73% is prepared, and the direct recovery rate of iridium is 86.5%.

[0089] From the comparison of Comparative Example 3 and Example 1, it can be seen that the direct recovery rate of iridium is reduced due to the lack of the purification treatment step.

[0090] The embodiments of the present application are only used to illustrate the present application, and do not limit the protection scope of the present application. The technical solutions of the present application can be variously changed and modified in specific embodiments and application ranges without departing from the spirit and essence of the present application.

Claims

1. A method for synthesizing high-purity chloroiridic acid, characterized in that: The specific steps are as follows: S1. Pre-treating an iridium source containing iridium metal; S2, reacting the pretreated iridium source with chlorine in a reactor to generate a chloroiridic acid solution; S3, purifying the chloroiridic acid solution to obtain chloroiridic acid crystals; S4, washing and drying the chloroiridic acid crystals to obtain a chloroiridic acid product.

2. A method for synthesizing high-purity chloroiridic acid according to claim 1, characterized in that, The iridium source in step S1 includes iridium powder, iridium ore and iridium-containing waste.

3. A method for synthesizing high-purity chloroiridic acid according to claim 1, characterized in that, The pretreatment in step S1 includes S11 ball milling the iridium source to make its particle size less than 50 μm.

4. A method for synthesizing high-purity chloroiridic acid according to claim 1, characterized in that, The pretreatment in step S1 further includes a method of acid washing and water washing in step S12 to purify the iridium source and remove impurities; The pickling step in step S12 is to place the iridium source in a dilute hydrochloric acid solution with a mass concentration of 15-20% and soak it for 2 hours; The water washing step in step S12 is to put the acid-washed iridium source into high-purity water and rinse it repeatedly until the water is neutral; Step S12: After washing with water, filtering and drying are performed. The specific operation of drying is to put the iridium source into an oven at 85° C. and keep it for 2 hours.

5. A method for synthesizing high-purity chloroiridic acid according to claim 1, characterized in that, The volume purity of the chlorine in step S2 is 99.0%-99.99%; In step S2, the reactor is in a concentrated hydrochloric acid environment, and the mass concentration of concentrated hydrochloric acid is 38%; In step S2, the mass ratio of the iridium source to the chlorine gas and the hydrochloric acid is 1:(3-5):

6.

6. A method for synthesizing high-purity chloroiridic acid according to claim 1, characterized in that, The temperature of the reactor in step S2 is 100-200° C.; the reaction time in step S2 is 5-8 hours.

7. A method for synthesizing high-purity chloroiridic acid according to claim 1, characterized in that: The pressure of the reactor in step S2 is 0.1-0.6 MPa.

8. A method for synthesizing high-purity chloroiridic acid according to claim 1, characterized in that: The purification method in step S3 includes filtration, purification and crystallization; The purification step is to purify the filtered chloroiridic acid solution by passing it through an ion exchange resin column, selecting a strong acid cation exchange resin, the exchange capacity of the resin is 4.5 mmol / g, the flow rate of the solution is 10 mL / min, and the number of times it passes through the ion exchange resin column is 2-6 times; The crystallization step is to concentrate the purified chloroiridic acid solution until solid precipitates, and then cool the concentrated solution to 10° C. and stir at this temperature for 4 hours to allow the chloroiridic acid to crystallize.

9. A method for synthesizing high-purity chloroiridic acid according to claim 1, characterized in that: The washing method in step S4 is to slowly rinse the crystal surface with 0-10° C. anhydrous ethanol, and repeat the rinsing 2-3 times.

10. The method for synthesizing high-purity chloroiridic acid according to claim 1, wherein: In step S4, the drying temperature is 40-50° C. and maintained for 2-3 hours.