Preparation method of ruthenium oxide with large specific surface area

Abstract

The invention discloses a preparation method of ruthenium oxide with a large specific surface area. The method comprises the following steps: 1, slowly adding a diluted diethanol amine solution into a ruthenium trichloride solution under a low-temperature condition, and stirring for reaction to obtain a hydrated ruthenium oxide suspension; and 2, quickly freezing the ruthenium oxide hydrate suspension, freeze-drying to obtain ruthenium oxide hydrate powder, and annealing at low temperature to obtain the ruthenium oxide powder with large specific surface area. The preparation method comprises the following steps: taking ruthenium trichloride as a raw material to prepare a solution, reacting the solution with a diluted diethanol amine solution precipitant, controlling the reaction temperature and rate of the solution and the diluted diethanol amine solution precipitant to obtain nano-crystalline ruthenium oxide hydrate, and then quickly freezing and drying to obtain the ruthenium oxide hydrate nano-powder with good dispersity. And low-temperature annealing is combined to remove impurities and prevent ruthenium oxide from agglomerating, the ruthenium oxide powder with high purity and large specific surface area is obtained, the method is suitable for the fields of thick-film resistor paste and water electrolysis hydrogen production catalysts, the process is simple, the yield is high, and industrial production is easy.

Description

Technical Field

[0001] The present invention belongs to the technical field of powder metallurgy, and particularly relates to a method for preparing ruthenium oxide with a large specific surface area. Background Art

[0002] Due to its excellent physical and chemical properties, ruthenium oxide has a very stable structure, corrosion resistance, a low resistance temperature coefficient, and high electrolytic water catalytic performance, which makes ruthenium oxide widely used in resistance components and industrial electrolytic water hydrogen production electrolytic cells. With the continuous development of technology, there is an even more urgent demand for ruthenium oxide, especially ruthenium oxide with a large specific surface area. A large specific surface area can greatly reduce the ruthenium content in the ruthenium oxide resistance paste, while improving the performance of the resistance and saving costs. In addition, ruthenium oxide with a large specific surface area has always been an important indicator for electrolytic water hydrogen production catalysts. During the electrolytic water catalysis process, the larger the specific surface area of the ruthenium oxide powder, the more ruthenium atoms are exposed, and thus the better the catalytic performance. At present, the main methods for preparing ruthenium oxide with a large specific surface area include liquid-phase chemical synthesis, sol-gel method, direct calcination method, etc. Although there are many methods for preparing ruthenium oxide, very few can be used in high-performance resistance pastes. Developing a preparation technology for ruthenium oxide with a large specific surface area is of great significance.

[0003] The patent with the publication number CN 114105228 A discloses a method for preparing ruthenium oxide with a large specific surface area. The invention includes: First, ruthenium trichloride and ammonium chloride are mixed and then ball-milled to obtain a mixed powder; Second, the mixed powder is calcined and reduced to obtain flaky ruthenium powder; Third, the flaky ruthenium powder is ball-milled to obtain nano ruthenium powder; Fourth, the nano ruthenium powder is calcined in air to obtain ruthenium oxide for thick film resistors. By controlling the ball milling of the precursor ruthenium salt, combining with controlling the morphology of the ruthenium powder, and then calcining in air, large-particle-size spherical ruthenium oxide powder is obtained, avoiding the ruthenium oxide powder inheriting the morphology of the flaky ruthenium powder, ensuring the spherical morphology of the ruthenium oxide powder, making it suitable for thick film resistors. At the same time, this preparation method has a simple process, a high yield, a large output, is green and environmentally friendly, and is easy for industrial production. Although the ruthenium oxide prepared by this method is suitable for some resistance pastes, the specific surface area of the ruthenium oxide prepared by this method is very small, the cost of the prepared resistance paste is very high, and this ruthenium oxide powder is not suitable for electrolytic water hydrogen production catalysts either.

[0004] The patent with the publication number CN106587180A discloses a preparation method of ruthenium dioxide for resistor paste. In this method, a ruthenium trichloride solution with a concentration of 0.011 mol / L and a quaternary ammonium salt solution with a concentration of 0.013 mol / L are first prepared. Then, according to a molar ratio of 1:35, the ruthenium trichloride solution is gradually added dropwise to the quaternary ammonium salt solution under heating and magnetic stirring conditions. After the addition is completed, stirring is stopped until the pH value of the solution reaches 7.8. The obtained black precipitate is washed with a centrifuge, filtered, and dried to obtain ruthenium dioxide, which can be used as a medium and low resistance material. However, in the preparation process of this method, it is not easy to control the experimental conditions, the prepared ruthenium oxide is prone to agglomeration, and there are many difficulties in industrialization.

[0005] The patent with the publication number CN115321616A discloses a preparation method of high specific surface area nano ruthenium oxide with low cost and controllable particle size. This method includes: First, prepare an aqueous ruthenium salt solution containing a dispersant and an aqueous weak base solution respectively; Second, use high-frequency electronic oscillation to respectively obtain a ruthenium-containing micro-nano aerosol and a weak base-containing micro-nano aerosol; Third, carry out a gas-phase confined micro-region mixing reaction on the ruthenium-containing micro-nano aerosol and the weak base-containing micro-nano aerosol; Fourth, carry out solid-liquid separation, washing, drying, and topological oxidation roasting in sequence to obtain high specific surface area nano ruthenium oxide. This invention uses ordinary low-cost soluble ruthenium salt as the ruthenium source, uses low-cost weak base as the reaction regulator and the nucleation and growth control agent, reacts by converting the ruthenium source and the weak base into micro-nano aerosol forms, constructs a three-dimensional space confined micro-region reaction condition, and controls the reaction kinetic conditions, increases the nucleation number, realizes the controllable preparation of the particle size of high specific surface area nano ruthenium oxide, and reduces the preparation cost. However, this process is complex, not easy to control, and it is unknown whether large-scale production can be achieved.

[0006] Therefore, there is an urgent need for a preparation method of ruthenium oxide with a large specific surface area. Summary of the Invention

[0007] The technical problem to be solved by the present invention is to provide a preparation method of ruthenium oxide with a large specific surface area in view of the deficiencies of the above-mentioned prior art. This method reacts a ruthenium trichloride solution with a diluted diethanolamine solution precipitant and controls the reaction temperature and rate of the two to obtain hydrated ruthenium oxide in the form of nanocrystals. Then, after rapid freezing and drying, a well-dispersed hydrated ruthenium oxide nanopowder is obtained. Combining with low-temperature annealing to remove impurities and prevent the agglomeration of ruthenium oxide, a ruthenium oxide powder with high purity and large specific surface area is obtained, solving the problems of small surface area, high cost, and complex and difficult-to-control process in the prior art for preparing ruthenium oxide powder.

[0008] To solve the above technical problems, the technical solution adopted by the present invention is: A preparation method of ruthenium oxide with a large specific surface area, characterized in that this method includes the following steps:

[0009] Step 1: Prepare a ruthenium trichloride solution using ruthenium trichloride as the raw material. Then, under low-temperature conditions, slowly add the diluted diethanolamine solution to the ruthenium trichloride solution and stir to react to obtain a ruthenium oxide hydrate suspension.

[0010] Step 2: Quickly freeze the ruthenium oxide hydrate suspension obtained in Step 1 in liquid nitrogen, and then freeze-dry it in a freeze-drying device to obtain ruthenium oxide hydrate powder. Then, perform low-temperature annealing in a tubular furnace to obtain ruthenium oxide powder with a large specific surface area.

[0011] Compared with the traditional method of preparing ruthenium oxide with a large specific surface area by reacting a reducing agent or a precipitating agent with a ruthenium solution, in this preparation process, a dispersant is added, and then ruthenium oxide powder is obtained through filtration and drying. This results in the ruthenium oxide powder having disadvantages such as easy agglomeration, difficult cleaning of the dispersant, difficult control, and a large amount of waste liquid. In the present invention, first, a solution is prepared using ruthenium trichloride as the raw material, and the diluted diethanolamine solution is slowly added under low-temperature conditions and stirred to react to prepare a ruthenium oxide hydrate suspension. Using the diluted diethanolamine solution as a precipitating agent, the reaction temperature and rate are controlled to allow the ruthenium oxide hydrate to slowly crystallize and precipitate, preventing the rapid growth of ruthenium oxide nanoparticles, effectively controlling the primary particle size of ruthenium oxide, and ensuring that the ruthenium oxide hydrate particles do not agglomerate to form nanocrystals. Then, the ruthenium oxide hydrate suspension is quickly frozen in liquid nitrogen to prevent the ruthenium oxide particles from settling and aggregating during the freezing process. Subsequently, the frozen ruthenium oxide hydrate is freeze-dried, avoiding the problem of powder agglomeration and a decrease in surface area caused by the traditional filtration and drying processes, and obtaining ruthenium oxide hydrate nanopowder with good dispersibility. Then, the ruthenium oxide hydrate nanopowder is annealed at low temperature in air to effectively remove the moisture and residual organic matter in the ruthenium oxide hydrate nanopowder, ensuring the mass purity of the product ruthenium oxide, and the low-temperature annealing prevents the product ruthenium oxide from agglomerating, ensuring that the obtained product, nanoscale ruthenium oxide, has a large specific surface area. Finally, the ruthenium oxide powder with a large surface area prepared by the present invention has the advantages of high purity and a large specific surface area. When applied to resistance pastes, while ensuring its performance, it greatly reduces the ruthenium consumption and cost. When applied to electrolytic water hydrogen production catalysts, it exhibits good catalytic activity. Therefore, the ruthenium oxide powder with a large specific surface area prepared by the present invention has broad application prospects.

[0012] In the above method for preparing ruthenium oxide with a large specific surface area, it is characterized in that in Step 1, the ruthenium element concentration in the ruthenium trichloride solution is 0.1 wt% to 3 wt%, the concentration of the diluted diethanolamine solution is 0.1 wt% to 0.5 wt%, and the volume ratio of the ruthenium trichloride solution to the diluted diethanolamine solution is 1:1 to 1:3. The temperature of the stirring reaction is 5 °C, and the time is 0.5 h to 4 h. The present invention effectively prepares a nanoscale ruthenium oxide hydrate suspension by controlling the concentrations of the raw material solution and the precipitating agent solution, the addition amount, and the stirring reaction temperature and time, preventing the agglomeration of ruthenium oxide hydrate.

[0013] The above preparation method of ruthenium oxide with a large specific surface area is characterized in that, in step two, the freeze-drying time is 12 h to 24 h, the low-temperature annealing temperature is 100 °C to 250 °C, and the time is 0.5 h to 4 h. Generally, the volume of the ruthenium hydroxide suspension rapidly cooled in liquid nitrogen at one time is 500 mL to ensure the rapid freezing effect; the freeze-drying power used is 1 kW. By controlling the process parameters of freeze-drying and low-temperature annealing, the present invention effectively prevents the obtained ruthenium oxide nanopowder from agglomerating, and ensures that the product ruthenium oxide powder has a high specific surface area.

[0014] The above preparation method of ruthenium oxide with a large specific surface area is characterized in that, in step two, the specific surface area of the ruthenium oxide powder with a large specific surface area is 30 m 2 / g to 80 m 2 / g, the particle size is less than 100 nm, and the mass content of ruthenium element is 75% to 76%. The ruthenium oxide powder prepared by the present invention has the advantages of high purity and large specific surface area. When used in resistor pastes, it can ensure the performance while greatly reducing the ruthenium consumption, reducing the cost, and can also be used as an electrolytic water hydrogen production catalyst, and shows good catalytic activity.

[0015] The present invention has the following advantages compared with the prior art:

[0016] 1. The present invention uses ruthenium trichloride as a raw material and a diluted diethanolamine solution as a precipitant, and controls the reaction temperature and rate of the two, so that the prepared ruthenium hydroxide slowly crystallizes out to form nanocrystals. Then, combined with rapid freezing in liquid nitrogen and freeze-drying, the dispersibility of the ruthenium hydroxide nanopowder is improved. After that, low-temperature annealing is carried out to remove residual organic substances in the water, improve the mass purity of ruthenium oxide, and effectively prevent ruthenium oxide from agglomerating, thereby obtaining ruthenium oxide powder with high purity and large specific surface area, which is suitable for the fields of thick film resistor pastes and electrolytic water hydrogen production catalysts.

[0017] 2. The preparation process of the present invention is simple, can stably and effectively control the specific surface area of ruthenium oxide, has a high yield, is easy to industrialize, and has broad application prospects.

[0018] 3. The specific surface area of the ruthenium oxide powder prepared by the present invention is 30 m 2 / g to 80 m 2 / g, the particle size is less than 100 nm, and the mass content of ruthenium element is 75% to 76%, which can meet the requirements of thick film resistor pastes and electrolytic water hydrogen production catalysts at the same time.

[0019] The technical solution of the present invention will be further described in detail below with reference to the drawings and embodiments. BRIEF DESCRIPTION OF THE DRAWINGS

[0020] Figure 1 It is a flow chart of the preparation method of ruthenium oxide with a large specific surface area of the present invention.

[0021] Figure 2 SEM image of ruthenium oxide powder with a large specific surface area prepared in Example 1 of the present invention.

[0022] Figure 3 XRD pattern of ruthenium oxide powder with a large specific surface area prepared in Example 1 of the present invention. Detailed implementation manners

[0023] Example 1

[0024] As Figure 1 shown, this example includes the following steps:

[0025] Step 1: Add ruthenium trichloride to deionized water to prepare a ruthenium trichloride solution with a ruthenium element concentration of 3 wt%. Then, under low-temperature conditions, slowly add a diluted diethanolamine solution with a concentration of 0.3 wt% to the ruthenium trichloride solution and stir to react. The volume ratio of the ruthenium trichloride solution to the diluted diethanolamine solution is 1:2. The temperature of the stirring reaction is controlled at 5°C and the time is 2 h to obtain a hydrated ruthenium oxide suspension.

[0026] Step 2: Put 500 mL of the hydrated ruthenium oxide suspension obtained in Step 1 into liquid nitrogen for rapid freezing, and then put it into a freeze-drying device for freeze-drying. The drying power is 1 kW and the freeze-drying time is 18 h to obtain hydrated ruthenium oxide powder. Then, put it into a tubular furnace for low-temperature annealing. The temperature of the low-temperature annealing is 100°C and the time is 4 h to obtain ruthenium oxide powder with a large specific surface area.

[0027] Figure 2 SEM image of ruthenium oxide powder with a large specific surface area prepared in this example. From Figure 2 it can be seen that the ruthenium oxide powder is of nanoscale size, has good dispersibility, the specific surface area is 50 m 2 / g to 70 m 2 / g, the particle size is less than 100 nm, and the mass content of ruthenium element is 75% - 76%.

[0028] Figure 3 XRD pattern of ruthenium oxide powder with a large specific surface area prepared in this example. From Figure 3 it can be seen that the comparison with the standard card shows that the product ruthenium oxide powder is a pure ruthenium oxide phase.

[0029] Example 2

[0030] As Figure 1 shown, this example includes the following steps:

[0031] Step 1: Add ruthenium(III) chloride to deionized water to prepare a ruthenium(III) chloride solution with a ruthenium element concentration of 0.3 wt%. Then, under low-temperature conditions, slowly add a diluted diethanolamine solution with a concentration of 0.2 wt% to the ruthenium(III) chloride solution and stir to react. The volume ratio of the ruthenium(III) chloride solution to the diluted diethanolamine solution is 1:1. Control the temperature of the stirring reaction at 5 °C and the time at 2 h to obtain a ruthenium hydrous oxide suspension;

[0032] Step 2: Put 500 mL of the ruthenium hydrous oxide suspension obtained in Step 1 into liquid nitrogen for rapid freezing, and then put it into a freeze-drying device for freeze-drying. The drying power is 1 kW, and the freeze-drying time is 24 h to obtain ruthenium hydrous oxide powder. Then put it into a tube furnace for low-temperature annealing. The temperature of the low-temperature annealing is 100 °C and the time is 0.5 h to obtain ruthenium oxide powder with a large specific surface area.

[0033] After testing, the ruthenium oxide powder prepared in this example is nanoscale in size, has good dispersibility, a specific surface area of 60 m 2 / g to 80 m 2 / g, a particle size less than 100 nm, and a ruthenium element mass content of 75% to 76%.

[0034] Example 3

[0035] As Figure 1 shown, this example includes the following steps:

[0036] Step 1: Add ruthenium(III) chloride to deionized water to prepare a ruthenium(III) chloride solution with a ruthenium element concentration of 0.1 wt%. Then, under low-temperature conditions, slowly add a diluted diethanolamine solution with a concentration of 0.5 wt% to the ruthenium(III) chloride solution and stir to react. The volume ratio of the ruthenium(III) chloride solution to the diluted diethanolamine solution is 1:2. Control the temperature of the stirring reaction at 5 °C and the time at 0.5 h to obtain a ruthenium hydrous oxide suspension;

[0037] Step 2: Put 500 mL of the ruthenium hydrous oxide suspension obtained in Step 1 into liquid nitrogen for rapid freezing, and then put it into a freeze-drying device for freeze-drying. The drying power is 1 kW, and the freeze-drying time is 12 h to obtain ruthenium hydrous oxide powder. Then put it into a tube furnace for low-temperature annealing. The temperature of the low-temperature annealing is 200 °C and the time is 2 h to obtain ruthenium oxide powder with a large specific surface area.

[0038] After testing, the ruthenium oxide powder prepared in this example is nanoscale in size, has good dispersibility, a specific surface area of 40 m 2 / g to 60 m 2 / g, a particle size less than 100 nm, and a ruthenium element mass content of 75% to 76%.

[0039] Example 4

[0040] AsFigure 1 As shown in the figure, this embodiment includes the following steps:

[0041] Step 1: Add ruthenium trichloride to deionized water to prepare a ruthenium trichloride solution with a ruthenium element concentration of 2 wt%. Then, under low-temperature conditions, slowly add a diluted diethanolamine solution with a concentration of 0.1 wt% to the ruthenium trichloride solution and stir for reaction. The volume ratio of the ruthenium trichloride solution to the diluted diethanolamine solution is 1:3. Control the temperature of the stirring reaction at 5 °C and the time at 4 h to obtain a ruthenium hydroxide suspension.

[0042] Step 2: Put 500 mL of the ruthenium hydroxide suspension obtained in Step 1 into liquid nitrogen for rapid freezing, and then put it into a freeze-drying device for freeze-drying. The drying power is 1 kW, and the freeze-drying time is 16 h to obtain ruthenium hydroxide powder. Then, put it into a tubular furnace for low-temperature annealing. The temperature of the low-temperature annealing is 250 °C and the time is 4 h to obtain ruthenium oxide powder with a large specific surface area.

[0043] After testing, the ruthenium oxide powder prepared in this embodiment is of nanoscale size, has good dispersibility, a specific surface area of 30 m 2 / g - 50 m 2 / g, a particle size less than 100 nm, and the ruthenium element mass content is 75% - 76%.

[0044] Example 5

[0045] As Figure 1 shown in the figure, this embodiment includes the following steps:

[0046] Step 1: Add ruthenium trichloride to deionized water to prepare a ruthenium trichloride solution with a ruthenium element concentration of 0.1 wt%. Then, under low-temperature conditions, slowly add a diluted diethanolamine solution with a concentration of 0.4 wt% to the ruthenium trichloride solution and stir for reaction. The volume ratio of the ruthenium trichloride solution to the diluted diethanolamine solution is 1:1. Control the temperature of the stirring reaction at 5 °C and the time at 3 h to obtain a ruthenium hydroxide suspension.

[0047] Step 2: Put 500 mL of the ruthenium hydroxide suspension obtained in Step 1 into liquid nitrogen for rapid freezing, and then put it into a freeze-drying device for freeze-drying. The drying power is 1 kW, and the freeze-drying time is 24 h to obtain ruthenium hydroxide powder. Then, put it into a tubular furnace for low-temperature annealing. The temperature of the low-temperature annealing is 150 °C and the time is 3 h to obtain ruthenium oxide powder with a large specific surface area.

[0048] After testing, the ruthenium oxide powder prepared in this embodiment is of nanoscale size, has good dispersibility, a specific surface area of 50 m 2 / g - 70 m 2 / g, a particle size less than 100 nm, and the ruthenium element mass content is 75% - 76%.

[0049] The above are only the preferred embodiments of the present invention, and do not impose any limitations on the present invention. Any simple modifications, changes, and equivalent variations made to the above embodiments based on the technical essence of the invention still fall within the scope of protection of the technical solution of the present invention.

Claims

1. A method for preparing ruthenium oxide with a large specific surface area, characterized in that: The method comprises the following steps: Step 1, preparing a ruthenium trichloride solution using ruthenium trichloride as a raw material, and then slowly adding a diluted diethanolamine solution to the ruthenium trichloride solution under low temperature conditions, stirring and reacting, to obtain a hydrated ruthenium oxide suspension; Step 2: The hydrated ruthenium oxide suspension obtained in step 1 is placed in liquid nitrogen for rapid freezing, and then placed in a freeze-drying device for freeze drying to obtain hydrated ruthenium oxide powder, and then placed in a tubular furnace for low-temperature annealing to obtain ruthenium oxide powder with a large specific surface area.

2. The method for preparing ruthenium oxide with a large specific surface area according to claim 1, characterized in that: In step 1, the concentration of ruthenium element in the ruthenium chloride solution is 0.1wt% to 3wt%, the concentration of the diluted diethanolamine solution is 0.1wt% to 0.5wt%, and the volume ratio of the ruthenium chloride solution to the diluted diethanolamine solution is 1:1 to 1:3, the temperature of the stirring reaction is 5°C, and the time is 0.5h to 4h.

3. The method for preparing ruthenium oxide with a large specific surface area according to claim 1, characterized in that: The freeze-drying time in step 2 is 12h to 24h, and the low-temperature annealing temperature is 100°C to 250°C for 0.5h to 4h.

4. The method for preparing ruthenium oxide with a large specific surface area according to claim 1, characterized in that: The specific surface area of ​​the large specific surface area ruthenium oxide powder in step 2 is 30m 2 / g~80m 2 / g, the particle size is less than 100nm, and the mass content of ruthenium element is 75% to 76%.

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