Preparation method of high-purity palladium chloride powder

Abstract

The invention relates to the technical field of platinum group metal compound preparation, in particular to a high-purity palladium chloride powder preparation method which specifically comprises the following steps: (1) high-purity palladium pelletizing treatment: after high-purity palladium powder and a binder are uniformly mixed according to a preset proportion, the high-purity palladium powder and the binder are subjected to pelletizing treatment to obtain palladium pellets with a preset size; (2) sintering the palladium pellets: transferring the palladium pellets into a quartz tube furnace, and sintering the palladium pellets in a weak oxidation environment at a first preset temperature to obtain porous palladium pellets; (3) chlorine purification; (4) preparing palladium chloride; (5) carrying out ultrasonic treatment on palladium chloride; and (6) drying treatment. The method has the advantages of short process flow, controllable product granularity, environment friendliness, high palladium chloride yield, low auxiliary material consumption, low cost, no waste liquid generation and the like, and has a wide application prospect.

Description

Technical Field

[0001] The invention relates to the technical field of preparation of platinum group metal compounds, and in particular to a method for preparing high-purity palladium chloride powder. Background Art

[0002] Palladium chloride, also known as palladium dichloride, is a reddish brown solid powder that is easily deliquescent palladium compound. Palladium chloride is the most commonly used palladium compound with the largest market demand among various palladium compounds. Qualified palladium chloride usually has the characteristics of high precious metal palladium content, good solubility, fine particle size, large specific surface area, high purity, and no nitrogen, sulfur and other metal impurities. Palladium chloride can be used as a key raw material and is widely used in the preparation of various palladium-containing catalysts, molecular sieves and other products. It can also be used in the preparation of key components in various semiconductor, electronic and other industries; palladium chloride is also used as a raw material to prepare other important palladium compounds for use in related industries; therefore, palladium chloride is widely used and the market demand has always been large.

[0003] Invention patent CN118479573A discloses a preparation method of palladium chloride, which relates to the technical field of palladium chloride, and comprises the following steps: hydrochloric acid and waste catalyst are moderated, iron powder is added to form an iron powder mixture, the iron powder mixture is cooled and then filtered, and crude palladium is obtained after the filter residue is washed with hydrochloric acid; aqua regia and crude palladium are mixed and allowed to stand for a period of time to dissolve, the crude palladium dissolved in aqua regia is heated, and a reaction of aqua regia dissolution is carried out in a reactor with a temperature sensor and a control system, concentrated hydrochloric acid is added during the reaction to drive out nitrate, the process of driving out nitrate is repeated to obtain a solution after nitrate removal, palladium chloride is prepared by the present invention, and the reaction is ensured to be carried out at an optimal temperature during the aqua regia dissolution process, thereby improving the quality and yield of the product, while reducing the generation of by-products and energy consumption.

[0004] Invention patent CN116573689A discloses a method for preparing palladium chloride, characterized in that it comprises the following steps: mixing polyvinyl pyrrolidone solution and hydrochloric acid to obtain a hydrochloric acid dispersant mixed solution; secondly mixing palladium powder, the hydrochloric acid dispersant mixed solution and hydrogen peroxide, stirring to obtain a chloropalladium acid solution; evaporating and crystallizing the chloropalladium acid solution, and sintering the obtained particles to obtain the palladium chloride. The present invention uses polyvinyl pyrrolidone as a dispersant to well control grain growth, so that the particle size of the palladium chloride finally prepared is within 10 μm.

[0005] The above method has obvious advantages, but it is necessary to first dissolve palladium into chloropalladic acid and transfer it into a solution, and then remove impurities from palladium through steps such as driving away nitrate and ammonia complexation, and then dissolve in aqua regia, drive away nitrate, concentrate, and crystallize into palladium chloride crystals, and grind to obtain a palladium chloride powder product. The above palladium chloride preparation method has the characteristics of long production process, large amount of reagents need to be consumed, resulting in increased reagent costs and easy to cause product impurities to exceed the standard during the production of palladium chloride; in addition, the above process has many steps, many control points, and the production process will produce a large amount of toxic and harmful nitrogen oxides, resulting in a long production cycle, the production process is difficult to control, and the problem of not being friendly to the environment appears. Finally, the above production steps need to be ground, and waste liquid is generated at the same time, and palladium loss and other problems are inevitably generated.

[0006] Therefore, based on the shortcomings of the existing preparation process of palladium chloride solid powder, it is of great significance to develop a process for preparing palladium chloride solid powder with a short process flow, low auxiliary material consumption, high product purity, environmental friendliness, and no loss of precious metal palladium. Summary of the invention

[0007] Features and advantages of the invention are set forth in part in the following description, or may be obvious from the description, or may be learned through practice of the invention.

[0008] In order to overcome the problems of the prior art, the present invention provides a method for preparing high-purity palladium chloride powder, which specifically comprises the following steps: (1) High-purity palladium pelletization treatment: high-purity palladium powder and a binder are uniformly mixed in a preset ratio, and then pelletized to obtain palladium pellets of a preset size; (2) Sintering of palladium pellets: transferring the palladium pellets to a quartz tube furnace and sintering them in a weakly oxidizing environment at a first preset temperature to obtain porous palladium balls; (3) Chlorine gas purification: Purified chlorine gas is obtained by passing chlorine gas through concentrated sulfuric acid and concentrated phosphoric acid solutions at room temperature; (4) preparing palladium chloride: introducing purified chlorine gas into a quartz tube furnace, maintaining the temperature at a second preset temperature for a first preset time, allowing the chlorine gas to fully contact and react with palladium, and when the reaction is complete and the reaction system no longer absorbs chlorine gas, stopping the supply of chlorine gas and heating to obtain palladium chloride, and absorbing the chlorinated tail gas with a sodium hydroxide aqueous solution and then discharging it; (5) Ultrasonic treatment of palladium chloride: the palladium chloride obtained in step (4) is transferred into a sealed quartz container and placed in an ultrasonic field, and at the same time, a dilute hydrochloric acid mist is sprayed into the container for a second preset time, and ultrasonic crushing is performed to obtain a soluble palladium chloride powder; (6) Drying treatment: The palladium chloride powder obtained in step (5) is transferred into a vacuum drying oven and dried at a third preset temperature to obtain high-purity palladium chloride.

[0009] Preferably, in step (4), when the reaction is complete and the reaction system no longer absorbs chlorine, the mass of the palladium pellets after the reaction increases to more than 1.66 times the mass of the original palladium pellets.

[0010] Preferably, the high-purity palladium powder needs to be sieved with a 130-170 mesh screen before mixing; the binder is any two or three of soluble starch, carboxymethyl cellulose, and short fiber cotton pulp mixed in any proportion to obtain a mixed bonding material, and then the mixed bonding material is slurried with pure water at a mass ratio of 0.01-0.8:1.

[0011] Preferably, in step (2), the first preset temperature is 150-360° C., the sintering holding time is 0.5-3.5 h, the laying thickness of the pellets in the quartz tube furnace is 15-35 mm, and the weak oxidation environment provider is air or pure oxygen.

[0012] Preferably, in step (3), the concentration of sulfuric acid is 90-98.5%, and the concentration of phosphoric acid is 83-98%.

[0013] Preferably, in step (4), the second preset temperature is 350-800° C., the first preset time is 0.5-3.5 h; and the concentration of sodium hydroxide is 1-20%.

[0014] Preferably, in step (5), the second preset time is 5-30 min; the concentration of hydrochloric acid is 0.1-3 mol / L; and the mass ratio of the amount of dilute hydrochloric acid mist to palladium chloride is 0.01-0.3:1.

[0015] Preferably, the third preset temperature is 40-85° C., and the drying time is 1.5-6.0 h.

[0016] Beneficial effects of the present invention: The present invention mixes high-purity palladium with a binder containing short-fiber cotton pulp and pelletizes the mixture, then puts the mixture into a quartz tube furnace for sintering to remove the binder, forms channels inside and outside the pellets, and is conducive to complete absorption and conversion of chlorine, and then places the converted pellets in ultrasonic waves and dilute hydrochloric acid mist for conversion and pulverization, and then obtains soluble palladium chloride with a particle size less than 100 mesh after vacuum drying. The method pelletizes and sinters palladium using a binder and short-fiber cotton pulp, and can keep the shape of the pellets from collapsing during the chlorination conversion process, and leaves channels inside and outside the pellets, which is conducive to absorbing chlorine to completely convert palladium into palladium chloride, ensuring that palladium is completely converted into palladium chloride, thereby achieving a high yield of palladium chloride. Ultrasonic high-frequency oscillation crushing of palladium chloride pellets is used to obtain extremely fine palladium chloride powder, without the need for ball milling, completely avoiding the dispersion loss of palladium chloride during the grinding process, and ensuring that the yield of palladium chloride is greater than 99.5%.

[0017] (1) Make full use of palladium, binder and short-fiber cotton pulp pelletization and sintering treatment. In the process of medium-temperature chlorination reaction of palladium and chlorine to convert palladium into palladium chloride, a channel is provided for the contact between palladium and chlorine inside the pellets, which provides the necessary conditions for the complete and thorough conversion of palladium into palladium chloride. The palladium chlorination conversion process can achieve low energy consumption, complete palladium conversion, no waste liquid generated in the conversion process, and no dispersion of precious metal palladium, so that the entire conversion process has the advantages of high conversion rate and controllable process.

[0018] (2) Place palladium chloride in a sealed container, and apply dilute hydrochloric acid mist and ultrasonic field to convert and pulverize the palladium chloride, and then vacuum dry at low temperature to obtain soluble palladium chloride powder. This process does not have a palladium chloride dispersion loss step. By controlling the length of ultrasonic oscillation time, palladium chloride powders of different particle sizes can be obtained, ensuring that the yield of palladium chloride is greater than 99.5%, and achieving the purpose of controlling the particle size of palladium chloride solid powder.

[0019] In summary, in the process of preparing palladium chloride solid powder product from palladium powder with a purity greater than 99.95%, the palladium chloride yield is greater than 99.5%, no ammonia and nitrogen residues are left in the product, and the product purity index is better than the national standard requirements. In the process of preparing palladium chloride powder without grinding, the present invention has the advantages of short process flow, controllable product particle size, environmental friendliness, high palladium chloride yield, less auxiliary materials, low cost, no waste liquid generation, etc., and has broad application prospects. BRIEF DESCRIPTION OF THE DRAWINGS

[0020] The present invention will be described in detail below with reference to the accompanying drawings and in combination with examples, and the advantages and implementation methods of the present invention will become more obvious. The contents shown in the accompanying drawings are only used to explain the present invention and do not constitute any limitation to the present invention in any sense. In the accompanying drawings: Figure 1 The figure is a process schematic diagram of a method for preparing high-purity palladium chloride powder in a specific embodiment of the present invention. DETAILED DESCRIPTION

[0021] The following embodiments of the present invention are described in further detail in conjunction with the accompanying drawings and examples. The following examples are used to illustrate the present invention, but are not intended to limit the scope of the present invention.

[0022] In the description of the present invention, unless otherwise specified, the terms “first”, “second”, etc. are used for descriptive purposes only and cannot be understood as indicating or implying relative importance.

[0023] Example 1

[0024] like Figure 1 As shown, the present invention provides a method for preparing high-purity palladium chloride powder, which specifically comprises the following steps: (1) High-purity palladium pelletization treatment: 100 g of 130-mesh high-purity palladium powder containing 99.97% palladium was taken. The binder used in this embodiment was prepared by mixing 2.5 g of short-fiber cotton pulp, 2.5 g of carboxymethyl cellulose and water. 15 ml of pure water was added to the uniformly mixed short-fiber cotton pulp and carboxymethyl cellulose. The mixture was heated and stirred to obtain a binder. After the high-purity palladium powder and the binder were uniformly mixed, the palladium was pelletized using a pelletizing device to obtain palladium pellets with a diameter of 20 mm. (2) Sintering of palladium pellets: Padding the palladium pellets in a quartz boat with a thickness of 20 mm, and sintering them in a weak oxidizing environment provided by air or pure oxygen, that is, placing the quartz boat in a quartz tube furnace, heating it to 150° C., and keeping it warm for 0.5 h for carbonization sintering to obtain porous palladium balls; (3) Chlorine gas purification: Purified chlorine gas is obtained by passing chlorine gas through 90% by mass concentrated sulfuric acid and 83% by mass concentrated phosphoric acid solution at room temperature; (4) Preparation of palladium chloride: The temperature is raised to 350° C., and the purified chlorine gas is introduced into a quartz tube furnace, and the temperature is kept for 3 hours to allow the chlorine gas to fully contact and react with the palladium. When the reaction is complete and the reaction system no longer absorbs chlorine gas, the chlorine gas supply and heating are stopped to obtain palladium chloride, and the palladium chloride is cooled and taken out. The chlorinated tail gas is absorbed by a sodium hydroxide aqueous solution and then discharged. The concentration of the sodium hydroxide is 1%. When the reaction is complete and the reaction system no longer absorbs chlorine gas, the mass of the palladium pellets after the reaction increases to more than 1.66 times the mass of the original palladium pellets. (5) Ultrasonic treatment of palladium chloride: The palladium chloride obtained in step (4) is transferred into a sealed quartz container and placed in an ultrasonic field. At the same time, 25.5 ml of dilute hydrochloric acid mist is sprayed into the container for 25 min. The hydrochloric acid concentration is 0.5 mol / L. Ultrasonic crushing treatment is performed to obtain soluble palladium chloride powder. (6) Drying treatment: The palladium chloride powder obtained in step (5) is transferred to a vacuum drying oven and dried at 40°C for 6 hours to obtain high-purity palladium chloride, which is then taken out and bottled. From the raw material to the palladium chloride powder, the yield of palladium chloride is 99.33%.

[0025] Example 2

[0026] This embodiment provides a method for preparing high-purity palladium chloride powder, which specifically comprises the following steps: (1) Pelletizing high-purity palladium: 158 g of 150-mesh high-purity palladium powder containing 99.97% palladium was taken. The binder used in this embodiment was prepared by mixing 20 g of short-fiber cotton pulp, 5 g of soluble starch and water. 50 ml of pure water was added to the uniformly mixed short-fiber cotton pulp and soluble starch. The mixture was heated and stirred to obtain a binder. After the high-purity palladium powder and the binder were uniformly mixed, the palladium was pelletized using a pelletizing device to obtain palladium pellets with a diameter of 15 mm. (2) Sintering of palladium pellets: Palladium pellets are laid in a quartz boat with a thickness of 30 mm, and sintered in a weak oxidizing environment provided by air or pure oxygen. That is, the quartz boat is placed in a quartz tube furnace, heated to 300° C., and kept warm for 2 hours for carbonization sintering to obtain porous palladium balls. (3) Chlorine gas purification: Purified chlorine gas is obtained by passing chlorine gas through 92% by mass concentrated sulfuric acid and 92% by mass concentrated phosphoric acid solution at room temperature; (4) Preparation of palladium chloride: The temperature is raised to 450° C., and the purified chlorine gas is introduced into a quartz tube furnace, and the temperature is kept for 0.5 h to allow the chlorine gas to fully contact and react with the palladium. When the reaction is complete and the reaction system no longer absorbs chlorine gas, the chlorine gas supply and heating are stopped to obtain palladium chloride, and the palladium chloride is taken out by cooling. The chlorinated tail gas is absorbed by a sodium hydroxide aqueous solution and then discharged, and the concentration of the sodium hydroxide is 10%; when the reaction is complete and the reaction system no longer absorbs chlorine gas, the mass of the palladium pellets after the reaction increases to more than 1.66 times the mass of the original palladium pellets; (5) Ultrasonic treatment of palladium chloride: The palladium chloride obtained in step (4) is transferred into a sealed quartz container and placed in an ultrasonic field. At the same time, 9 ml of dilute hydrochloric acid mist is sprayed into the container for 5 min. The hydrochloric acid concentration is 3 mol / L. Ultrasonic crushing treatment is performed to obtain soluble palladium chloride powder. (6) Drying treatment: The palladium chloride powder obtained in step (5) is transferred to a vacuum drying oven and dried at 50°C for 5 hours to obtain high-purity palladium chloride, which is then taken out and bottled. From the raw material to the palladium chloride powder, the yield of palladium chloride is 99.98%.

[0027] Example 3

[0028] This embodiment provides a method for preparing high-purity palladium chloride powder, which specifically comprises the following steps: (1) Pelletizing high-purity palladium: 80 g of 170-mesh high-purity palladium powder containing 99.67% palladium was taken. The binder used in this embodiment was prepared by mixing 3 g of short-fiber cotton pulp, 2 g of soluble starch and water. 15 ml of pure water was added to the uniformly mixed short-fiber cotton pulp and soluble starch. The mixture was heated and stirred to obtain a binder. After the high-purity palladium powder and the binder were uniformly mixed, the palladium was pelletized using a pelletizing device to obtain palladium pellets with a diameter of 35 mm. (2) Sintering of palladium pellets: Palladium pellets are laid in a quartz boat with a thickness of 35 mm and sintered in a weak oxidizing environment provided by air or pure oxygen. That is, the quartz boat is placed in a quartz tube furnace, heated to 360° C., and kept warm for 3 hours for carbonization sintering to obtain porous palladium balls. (3) Chlorine gas purification: Purified chlorine gas is obtained by passing chlorine gas through 95% concentrated sulfuric acid and 95% concentrated phosphoric acid solution at room temperature in sequence; (4) Preparation of palladium chloride: The temperature is maintained at 360° C., and the purified chlorine gas is introduced into a quartz tube furnace, and the temperature is kept for 3.5 hours to allow the chlorine gas to fully contact and react with the palladium. When the reaction is complete and the reaction system no longer absorbs chlorine gas, the chlorine gas supply and heating are stopped to obtain palladium chloride, and the palladium chloride is cooled and taken out. The chlorinated tail gas is absorbed by a sodium hydroxide aqueous solution and then discharged. The concentration of the sodium hydroxide is 15%; when the reaction is complete and the reaction system no longer absorbs chlorine gas, the mass of the palladium pellets after the reaction increases to more than 1.66 times the mass of the original palladium pellets; (5) Ultrasonic treatment of palladium chloride: The palladium chloride obtained in step (4) is transferred into a sealed quartz container and placed in an ultrasonic field. At the same time, 20.5 ml of dilute hydrochloric acid mist is sprayed into the container for 15 min. The hydrochloric acid concentration is 1.5 mol / L. Ultrasonic crushing treatment is performed to obtain soluble palladium chloride powder. (6) Drying treatment: The palladium chloride powder obtained in step (5) is transferred to a vacuum drying oven and dried at 60°C for 4 hours to obtain high-purity palladium chloride, which is then taken out and bottled. From the raw material to the palladium chloride powder, the yield of palladium chloride is 100%.

[0029] Example 4

[0030] This embodiment provides a method for preparing high-purity palladium chloride powder, which specifically comprises the following steps: (1) Pelletizing high-purity palladium: 300 g of 140-mesh high-purity palladium powder containing 99.67% palladium was taken. The binder used in this embodiment was prepared by mixing 30 g of short-fiber cotton pulp, 30 g of soluble starch and water. 100 ml of pure water was added to the uniformly mixed short-fiber cotton pulp and soluble starch. The mixture was heated and stirred to obtain a binder. After the high-purity palladium powder and the binder were uniformly mixed, the palladium was pelletized using a pelletizing device to obtain palladium pellets with a diameter of 15 mm. (2) Sintering of palladium pellets: Padding the palladium pellets in a quartz boat with a thickness of 30 mm, and sintering them in a weak oxidizing environment provided by air or pure oxygen, that is, placing the quartz boat in a quartz tube furnace, heating it to 250° C., and keeping it warm for 1.5 hours for carbonization sintering to obtain porous palladium balls; (3) Chlorine gas purification: Purified chlorine gas is obtained by passing chlorine gas through 97% concentrated sulfuric acid and 97% concentrated phosphoric acid solution at room temperature in sequence; (4) Preparation of palladium chloride: The temperature is raised to 550° C., and the purified chlorine gas is introduced into a quartz tube furnace, and the temperature is kept for 1.5 hours to allow the chlorine gas to fully contact and react with the palladium. When the reaction is complete and the reaction system no longer absorbs chlorine gas, the chlorine gas supply and heating are stopped to obtain palladium chloride, and the palladium chloride is taken out by cooling. The chlorinated tail gas is absorbed by a sodium hydroxide aqueous solution and then discharged, and the concentration of the sodium hydroxide is 20%; when the reaction is complete and the reaction system no longer absorbs chlorine gas, the mass of the palladium pellets after the reaction increases to more than 1.66 times the mass of the original palladium pellets; (5) Ultrasonic treatment of palladium chloride: The palladium chloride obtained in step (4) is transferred into a sealed quartz container and placed in an ultrasonic field. At the same time, 35 ml of dilute hydrochloric acid mist is sprayed into the container for 30 min. The hydrochloric acid concentration is 2 mol / L. Ultrasonic crushing treatment is performed to obtain soluble palladium chloride powder. (6) Drying treatment: The palladium chloride powder obtained in step (5) is transferred into a vacuum drying oven and dried at 78°C for 2.5 hours to obtain high-purity palladium chloride, which is then taken out and bottled. From the raw material to the palladium chloride powder, the yield of palladium chloride is 100%.

[0031] Example 5

[0032] This embodiment provides a method for preparing high-purity palladium chloride powder, which specifically comprises the following steps: (1) Pelletizing high-purity palladium: 230 g of 165-mesh high-purity palladium powder containing 99.67% palladium was taken. The binder used in this embodiment was prepared by mixing 25 g of short-fiber cotton pulp, 35 g of soluble starch and water. 75 ml of pure water was added to the uniformly mixed short-fiber cotton pulp and soluble starch. The mixture was heated and stirred to obtain a binder. After the high-purity palladium powder and the binder were uniformly mixed, the palladium was pelletized using a pelletizing device to obtain palladium pellets with a diameter of 25 mm. (2) Sintering of palladium pellets: Padding the palladium pellets in a quartz boat with a thickness of 25 mm, and sintering them in a weak oxidizing environment provided by air or pure oxygen, that is, placing the quartz boat in a quartz tube furnace, heating it to 160° C., and keeping it warm for 3.4 hours for carbonization sintering to obtain porous palladium balls; (3) Chlorine gas purification: Purified chlorine gas is obtained by passing chlorine gas through 93% concentrated sulfuric acid and 90% concentrated phosphoric acid solution at room temperature in sequence; (4) Preparation of palladium chloride: The temperature is raised to 600° C., and the purified chlorine gas is introduced into a quartz tube furnace, and the temperature is kept for 1 hour to allow the chlorine gas to fully contact and react with the palladium. When the reaction is complete and the reaction system no longer absorbs chlorine gas, the chlorine gas supply and heating are stopped to obtain palladium chloride, and the palladium chloride is taken out by cooling. The chlorinated tail gas is absorbed by a sodium hydroxide aqueous solution and then discharged, and the concentration of the sodium hydroxide is 18%; when the reaction is complete and the reaction system no longer absorbs chlorine gas, the mass of the palladium pellets after the reaction increases to more than 1.66 times the mass of the original palladium pellets; (5) Ultrasonic treatment of palladium chloride: The palladium chloride obtained in step (4) is transferred into a sealed quartz container and placed in an ultrasonic field. At the same time, 27 ml of dilute hydrochloric acid mist is sprayed into the container for 28 min. The hydrochloric acid concentration is 2.5 mol / L. Ultrasonic crushing treatment is performed to obtain soluble palladium chloride powder. (6) Drying treatment: The palladium chloride powder obtained in step (5) is transferred to a vacuum drying oven and dried at 45°C for 5.5 hours to obtain high-purity palladium chloride, which is then taken out and bottled. From the raw material to the palladium chloride powder, the yield of palladium chloride is 99.81%.

[0033] Example 6

[0034] This embodiment provides a method for preparing high-purity palladium chloride powder, which specifically comprises the following steps: (1) Pelletizing high-purity palladium: 200 g of 135-mesh high-purity palladium powder containing 99.97% palladium was taken. The binder used in this embodiment was prepared by mixing 20 g of short-fiber cotton pulp, 5 g of carboxymethyl cellulose, 25 g of soluble starch and water. 5 L of pure water was added to the uniformly mixed short-fiber cotton pulp, carboxymethyl cellulose and soluble starch. The mixture was heated and stirred to obtain a binder. After the high-purity palladium powder and the binder were uniformly mixed, the palladium was pelletized using a pelletizing device to obtain palladium pellets with a diameter of 15 mm. (2) Sintering of palladium pellets: Palladium pellets are laid in a quartz boat with a thickness of 15 mm and sintered in a weak oxidizing environment provided by air or pure oxygen. That is, the quartz boat is placed in a quartz tube furnace, heated to 350° C., and kept warm for 3.3 hours for carbonization sintering to obtain porous palladium balls. (3) Chlorine gas purification: Purified chlorine gas is obtained by passing chlorine gas through 98% concentrated sulfuric acid and 88% concentrated phosphoric acid solution at room temperature in sequence; (4) Preparation of palladium chloride: The temperature is raised to 700° C., and the purified chlorine gas is introduced into a quartz tube furnace, and the temperature is kept for 2 hours to allow the chlorine gas to fully contact and react with the palladium. When the reaction is complete and the reaction system no longer absorbs chlorine gas, the chlorine gas supply and heating are stopped to obtain palladium chloride, and the palladium chloride is taken out by cooling. The chlorinated tail gas is absorbed by a sodium hydroxide aqueous solution and then discharged. The concentration of the sodium hydroxide is 2%. When the reaction is complete and the reaction system no longer absorbs chlorine gas, the mass of the palladium pellets after the reaction increases to more than 1.66 times the mass of the original palladium pellets. (5) Ultrasonic treatment of palladium chloride: The palladium chloride obtained in step (4) is transferred into a sealed quartz container and placed in an ultrasonic field. At the same time, 32 ml of dilute hydrochloric acid mist is sprayed into the container for 10 min. The hydrochloric acid concentration is 1 mol / L. Ultrasonic crushing treatment is performed to obtain soluble palladium chloride powder. (6) Drying treatment: The palladium chloride powder obtained in step (5) is transferred to a vacuum drying oven and dried at 71°C for 3 hours to obtain high-purity palladium chloride, which is then taken out and bottled. From the raw material to the palladium chloride powder, the yield of palladium chloride is 99.67%.

[0035] Example 7

[0036] This embodiment provides a method for preparing high-purity palladium chloride powder, which specifically comprises the following steps: (1) Pelletizing high-purity palladium: 50 g of 160-mesh high-purity palladium powder containing 99.5% palladium was taken. The binder used in this embodiment was prepared by mixing 3.5 g of short-fiber cotton pulp, 2 g of carboxymethyl cellulose, 1 g of soluble starch and water. 15 ml of pure water was added to the uniformly mixed short-fiber cotton pulp, carboxymethyl cellulose and soluble starch. The mixture was heated and stirred to obtain a binder. After the high-purity palladium powder and the binder were uniformly mixed, the palladium was pelletized using a pelletizing device to obtain palladium pellets with a diameter of 30 mm. (2) Sintering of palladium pellets: Padding the palladium pellets in a quartz boat with a thickness of 30 mm, and sintering them in a weak oxidizing environment provided by air or pure oxygen, that is, placing the quartz boat in a quartz tube furnace, heating it to 200° C., and keeping it warm for 3.5 hours for carbonization sintering to obtain porous palladium balls; (3) Chlorine gas purification: Purified chlorine gas is obtained by passing chlorine gas through 98.5% concentrated sulfuric acid and 98% concentrated phosphoric acid solution at room temperature in sequence; (4) Preparation of palladium chloride: The temperature is raised to 800° C., and the purified chlorine gas is introduced into a quartz tube furnace, and the temperature is kept for 2.5 hours to allow the chlorine gas to fully contact and react with the palladium. When the reaction is complete and the reaction system no longer absorbs chlorine gas, the chlorine gas supply and heating are stopped to obtain palladium chloride, and the palladium chloride is cooled and taken out. The chlorinated tail gas is absorbed by a sodium hydroxide aqueous solution and then discharged. The concentration of the sodium hydroxide is 5%. When the reaction is complete and the reaction system no longer absorbs chlorine gas, the mass of the palladium pellets after the reaction increases to more than 1.66 times the mass of the original palladium pellets. (5) Ultrasonic treatment of palladium chloride: The palladium chloride obtained in step (4) is transferred into a sealed quartz container and placed in an ultrasonic field. At the same time, 15 ml of dilute hydrochloric acid mist is sprayed into the container for 20 min. The hydrochloric acid concentration is 0.1 mol / L. Ultrasonic crushing treatment is performed to obtain soluble palladium chloride powder. (6) Drying treatment: The palladium chloride powder obtained in step (5) is transferred to a vacuum drying oven and dried at 85°C for 1.5 hours to obtain high-purity palladium chloride, which is then taken out and bottled. From the raw material to the palladium chloride powder, the yield of palladium chloride is 99.92%.

[0037] Comparative Example 1: The following scheme is used to prepare high-purity palladium chloride powder, which specifically includes the following steps:

[0038] Step 1: After hydrochloric acid and waste catalyst are moderated, iron powder is added to form an iron powder mixture, and after the iron powder mixture is dissolved, the iron powder mixture is heated to boiling; Step 2, the iron powder mixture is cooled and then filtered, and the filter residue is washed with hydrochloric acid to obtain crude palladium; Step 3, mixing aqua regia and crude palladium and standing for a period of time to dissolve, heating the crude palladium dissolved in aqua regia, and performing a reaction of the aqua regia dissolution in a reactor equipped with a temperature sensor and a control system, adding concentrated hydrochloric acid to drive out nitrate during the reaction, repeating the process of driving out nitrate, and obtaining a nitrate solution; Step 4: Heat the nitrate solution with concentrated ammonia water to adjust the pH value, and control the temperature of the nitrate solution to 63°C during the ammoniation process; Step 5: After ammoniation, concentrated hydrochloric acid is added to the solution to lower the pH value. The temperature of the acidification process is 60° C. After acidification, the solution is cooled and filtered, and the filter residue is washed with hydrochloric acid to obtain a yellow precipitate; Step 6: Add concentrated ammonia water to the yellow precipitate to dissolve and adjust the pH value. The temperature of the dissolution process is 40°C. After dissolution, cool the excess, wash with dilute ammonia water, add hydrazine hydrate, stir at 50°C for 10 minutes, cool and filter, and then wash the filter residue with deionized water to obtain sponge palladium; Step 7, sponge palladium and aqua regia dissolution reaction continue to heat, heated by a reactor with a temperature sensor and a control system, after heating, concentrated hydrochloric acid is added to catch up with nitre, repeat to catch up with nitre to adjust pH value, and dry to obtain reddish brown palladium chloride powder after evaporation in a water bath. The yield of palladium chloride is 98%. The palladium chloride particle size obtained is a particle greater than 20 meshes, and some particles are united into a block. The palladium chloride obtained is transferred to a closed quartz container and placed in an ultrasonic field. The palladium chloride obtained after ultrasonic fragmentation treatment has uneven particles and some palladium chloride particles have a particle size greater than 1cm, and ball milling is still required. The palladium chloride after ultrasonic treatment is ball milled using a ball mill, and the yield of palladium chloride after ball milling is 92.7%.

[0039] The preferred embodiments of the present invention are described above with reference to the accompanying drawings. A person skilled in the art may implement the present invention in a variety of variations without departing from the scope and essence of the present invention. For example, a feature shown or described as part of one embodiment may be used in another embodiment to obtain another embodiment. The above are only preferred feasible embodiments of the present invention, and do not limit the scope of rights of the present invention. Any equivalent changes made using the contents of the present specification and the accompanying drawings are included in the scope of rights of the present invention.

Claims

1. A method for preparing high-purity palladium chloride powder, characterized in that, The specific steps include: (1) High-purity palladium pelletization treatment: high-purity palladium powder and a binder are uniformly mixed in a preset ratio, and then pelletized to obtain palladium pellets of a preset size; (2) Sintering of palladium pellets: transferring the palladium pellets to a quartz tube furnace and sintering them in a weakly oxidizing environment at a first preset temperature to obtain porous palladium balls; (3) Chlorine gas purification: Purified chlorine gas is obtained by passing chlorine gas through concentrated sulfuric acid and concentrated phosphoric acid solutions at room temperature; (4) preparing palladium chloride: introducing purified chlorine gas into a quartz tube furnace, maintaining the temperature at a second preset temperature for a first preset time, allowing the chlorine gas to fully contact and react with palladium, and when the reaction is complete and the reaction system no longer absorbs chlorine gas, stopping the supply of chlorine gas and heating to obtain palladium chloride, and absorbing the chlorinated tail gas with a sodium hydroxide aqueous solution and then discharging it; (5) Ultrasonic treatment of palladium chloride: the palladium chloride obtained in step (4) is transferred into a sealed quartz container and placed in an ultrasonic field, and at the same time, a dilute hydrochloric acid mist is sprayed into the container for a second preset time, and ultrasonic crushing is performed to obtain a soluble palladium chloride powder; (6) Drying treatment: The palladium chloride powder obtained in step (5) is transferred into a vacuum drying oven and dried at a third preset temperature to obtain high-purity palladium chloride.

2. the preparation method of a kind of high-purity palladium chloride powder according to claim 1 is characterized in that, In step (4), when the reaction is complete and the reaction system no longer absorbs chlorine, the mass of the palladium pellets after the reaction increases to more than 1.66 times the mass of the original palladium pellets.

3. The preparation method of a high-purity palladium chloride powder according to claim 1, wherein The high-purity palladium powder needs to be sieved with a 130-170 mesh screen before mixing; the binder is any two or three of soluble starch, carboxymethyl cellulose, and short-fiber cotton pulp mixed in any proportion to obtain a mixed bonding material, and then the mixed bonding material is slurried with pure water at a mass ratio of 0.01-0.8:

1.

4. the preparation method of a kind of high-purity palladium chloride powder according to claim 1 is characterized in that, In the step (2), the first preset temperature is 150-360° C., the sintering holding time is 0.5-3.5 h, the laying thickness of the pellets in the quartz tube furnace is 15-35 mm, and the weak oxidation environment provider is air or pure oxygen.

5. The preparation method of a high-purity palladium chloride powder according to claim 1, wherein In the step (3), the concentration of sulfuric acid is 90-98.5%, and the concentration of phosphoric acid is 83-98%.

6. The preparation method of a high-purity palladium chloride powder according to claim 1, wherein In the step (4), the second preset temperature is 350-800° C., the first preset time is 0.5-3.5 hours, and the concentration of the sodium hydroxide is 1-20%.

7. The preparation method of a high-purity palladium chloride powder according to claim 1, wherein In the step (5), the second preset time is 5-30 min; the hydrochloric acid concentration is 0.1-3 mol / L; and the mass ratio of the amount of the dilute hydrochloric acid mist to palladium chloride is 0.01-0.3:

1.

8. A method for preparing high-purity palladium chloride powder according to claim 1, characterized in that, The third preset temperature is 40-85° C., and the drying time is 1.5-6.0 h.

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