A method for recovering active metals from a hydrophobic catalyst

Abstract

This application relates to the field of nuclear reaction technology and provides a method for recovering active metals from a hydrophobic catalyst. The hydrophobic catalyst includes an active metal and a catalyst support. The catalyst support has channels, and the active metal is located within the channels of the catalyst support. The method includes: mixing the hydrophobic catalyst with aqua regia and pressurizing it to allow the aqua regia to enter the channels of the catalyst support and dissolve the active metal to obtain a solution; filtering the solution to obtain a filtrate; and reducing the active metal in the filtrate. This application provides a method for recovering active metals from a hydrophobic catalyst, which is capable of recovering active metals.

Description

Technical Field

[0001] This application relates to the field of nuclear reaction technology, and more particularly to a method for recovering active metals from hydrophobic catalysts. Background Technology

[0002] Hydrophobic catalysts, containing active metals, are commonly used in heavy water upgrading, volume reduction of tritium-containing wastewater, heavy water generation, ultrapure water production, hydrogenation of organic matter, and oxidation. During use, the catalytic activity of hydrophobic catalysts continuously decreases or even deactivates due to factors such as agglomeration, loss, poisoning of the active components, and changes in the catalyst support framework, rendering them unusable. Therefore, metal recovery from hydrophobic catalysts is of great significance in avoiding resource waste. Summary of the Invention

[0003] In view of this, embodiments of this application aim to provide a method for recovering metals from hydrophobic catalysts.

[0004] To achieve the above objectives, the technical solution of this application embodiment is implemented as follows: This application discloses a method for recovering an active metal from a hydrophobic catalyst, wherein the hydrophobic catalyst comprises an active metal and a catalyst support, the catalyst support having channels, and the active metal being located within the channels of the catalyst support. The method includes: The hydrophobic catalyst is mixed with aqua regia and pressurized to allow the aqua regia to enter the pores of the catalyst support and dissolve the active metal to obtain a solution. The solution is then filtered to obtain a filtrate. The active metal in the filtrate is reduced.

[0005] In one embodiment, the step of mixing the hydrophobic catalyst with aqua regia and pressurizing it to allow the aqua regia to enter the pores of the catalyst support and dissolve the active metal to obtain a solution includes: A mixture is obtained by adding the aqua regia and the hydrophobic catalyst in a predetermined volume ratio to a container; The container is pressurized to a preset pressure, and the mixture is stirred at a preset stirring speed for a preset reaction time. Then the pressure in the container is reduced to normal pressure to obtain the solution.

[0006] In one embodiment, the method includes: subjecting the mixture in the container to multiple pressurization-depressurization operations until the active metal dissolves.

[0007] In one embodiment, the preset volume ratio is the volume ratio of the aqua regia to the hydrophobic catalyst, and the preset volume ratio is between 1:1 and 3:1.

[0008] In one embodiment, the preset pressure is between 3 MPa and 10 MPa; and / or, The reaction time is between 10 min and 30 min; and / or, The preset stirring speed is between 60 r / min and 200 r / min.

[0009] In one embodiment, the method includes heating the hydrophobic catalyst and the aqua regia at a preset temperature.

[0010] In one embodiment, the preset temperature is between 50°C and 130°C.

[0011] In one embodiment, before reducing the active metal in the filtrate, the method includes: The filtrate is heated to remove nitrates and evaporated to concentrate it at a set temperature.

[0012] In one embodiment, the step of reducing the active metal in the filtrate includes: Ammonia is added to the filtrate, and after the pH value of the filtrate is determined to reach a first set value, a reducing agent is added.

[0013] In one embodiment, the reducing agent is at least one of methanol, formaldehyde, ethanol, acetone, and hydrazine hydrate.

[0014] In one embodiment, the active metal is platinum, and the catalyst support is polystyrene-divinylbenzene.

[0015] In one embodiment, the step of filtering the solution to obtain a filtrate includes: The catalyst support in the solution is filtered out to obtain the first filtrate; The catalyst support was washed multiple times with hydrochloric acid and / or water to obtain a washing solution. The first filtrate and the washing solution are mixed to obtain the filtrate.

[0016] This application provides a method for recovering active metals from a hydrophobic catalyst. By using aqua regia to dissolve the active metals, the dissolution efficiency is high, and the method is applicable to various metals, demonstrating strong versatility. By mixing the hydrophobic catalyst with aqua regia and then pressurizing the mixture, the pores of the catalyst support can be opened. This allows the aqua regia to enter the pores of the catalyst support and react with the active metals, dissolving them. This solves the problem that active metals in the pores of hydrophobic catalysts cannot be dissolved using inorganic acids, increasing the amount of active metal dissolved and thus improving the recovery rate. Finally, the filtered filtrate is reduced to obtain the active metals, achieving resource recycling. Attached Figure Description

[0017] Figure 1 This is a schematic flowchart of a method for recovering active metals from a hydrophobic catalyst, provided as an embodiment of this application. Detailed Implementation

[0018] It should be noted that, unless otherwise specified, the embodiments and technical features in the embodiments of this application can be combined with each other, and the detailed descriptions in the specific implementation should be understood as explanations of the purpose of this application and should not be regarded as undue limitations on this application.

[0019] The present application will now be described in further detail with reference to the accompanying drawings and specific embodiments. The terms "first," "second," etc., used in the embodiments of this application are for descriptive purposes only and should not be construed as indicating or implying their relative importance or implicitly including at least one feature. In the description of the embodiments of this application, "multiple" means at least two, such as two, three, etc., unless otherwise explicitly specified.

[0020] In related technologies, when recovering metals from hydrophobic catalysts, only the metals on the surface can be recovered due to the hydrophobicity of the catalyst, resulting in a low metal recovery rate.

[0021] This application provides a method for recovering an active metal from a hydrophobic catalyst. The hydrophobic catalyst includes an active metal and a catalyst support. The catalyst support has channels, and the active metal is located within the channels of the catalyst support. (See also...) Figure 1 The methods include: S1. The hydrophobic catalyst is mixed with aqua regia and pressurized to allow the aqua regia to enter the pores of the catalyst support and dissolve the active metal to obtain a solution. The solution is then filtered to obtain a filtrate. S2. Reduce the active metal in the filtrate.

[0022] This application provides a method for recovering active metals from a hydrophobic catalyst. By using aqua regia to dissolve the active metals, the dissolution efficiency is high, and the method is applicable to various metals, demonstrating strong versatility. By mixing the hydrophobic catalyst with aqua regia and then pressurizing the mixture, the pores of the catalyst support can be opened. This allows the aqua regia to enter the pores of the catalyst support and react with the active metals, dissolving them. This solves the problem that active metals in the pores of hydrophobic catalysts cannot be dissolved using inorganic acids, increasing the amount of active metal dissolved and thus improving the recovery rate. Finally, the filtered filtrate is reduced to obtain the active metals, achieving resource recycling.

[0023] It should be noted that the active metal dissolved in the pores of the catalyst support by aqua regia is in an ionic state. For example, nitrate and chloride ions in the aqua regia can react chemically with the active metal ions. The active metal that is finally reduced is an elemental active metal.

[0024] In one exemplary embodiment, the catalyst support is a porous medium.

[0025] In one embodiment, the active metal is platinum (Pt), and the catalyst support is polystyrene-divinylbenzene (SDB). It is understood that the Pt / SDB hydrophobic catalyst is a supported noble metal catalyst and is crucial for realizing the water-hydrogen isotope liquid-phase catalytic exchange reaction. The water-hydrogen isotope liquid-phase catalytic exchange reaction includes two processes: interphase transformation and catalytic exchange reaction. Specifically, on the hydrophilic material, the main process is vapor-liquid interphase transformation, while on the hydrophobic catalyst, the main process is hydrogen isotope catalytic exchange reaction. The specific process is as follows: Vapor-liquid phase transformation: HDO(l) + H2O(g) = HDO(g) + H2O(l) Hydrogen isotope catalytic exchange reaction: HDO(g) + H2(g) = H2O(g) + HD(g) Overall reaction: HDO(l) + H2(g) = H2O(l) + HD(g) Thus, the method provided in this embodiment can recover the precious metal platinum from deactivated waste Pt / SDB hydrophobic catalysts, and the method is simple, easy to implement, and has the characteristics of high purity of recovered platinum.

[0026] In one embodiment, the step of S1, mixing the hydrophobic catalyst with aqua regia and pressurizing it to allow the aqua regia to enter the pores of the catalyst support and dissolve the active metal to obtain a solution, includes: S11. Add the aqua regia and the hydrophobic catalyst in a preset volume ratio to a container to obtain a mixed solution; S12. Pressurize the container to a preset pressure, stir the mixture at a preset stirring speed within a preset reaction time, and then reduce the pressure of the container to normal pressure to obtain the solution.

[0027] Here, firstly, a hydrophobic catalyst and aqua regia are prepared according to a preset volume ratio. Then, the two are mixed in a container to obtain a mixed solution. Subsequently, the pressure inside the container is increased to a preset pressure, and the mixed solution is stirred at a stirring speed within a preset reaction time. This allows the aqua regia to enter the pores of the catalyst support and fully react with the active metal before flowing out from the pores of the catalyst support. Finally, the pressure inside the container is reduced to atmospheric pressure, which closes the pores of the catalyst support to prevent the solution from entering the pores of the catalyst and reducing the recovery rate of the active metal.

[0028] For example, in one embodiment, the container can be an autoclave, such as a corrosion-resistant autoclave, so that it can withstand a certain pressure and also have high corrosion resistance to resist acid erosion.

[0029] In one embodiment, the preset volume ratio is the volume ratio of aqua regia to hydrophobic catalyst, and the preset volume ratio is between 1:1 and 3:1. For example, the preset volume ratio can be 1:1, 1.2:1, 1.5:1, 1.7:1, 2:1, 2.2:1, 2.5:1, 2.7:1, or 3:1, etc., specifically based on the requirement that the aqua regia can completely submerge the hydrophobic catalyst in the container. This allows the active metal in the pores of the hydrophobic catalyst to react fully with the aqua regia, improving the solubility of the active metal.

[0030] In one embodiment, the preset pressure is between 3 MPa and 10 MPa. For example, the preset pressure can be 3 MPa, 4 MPa, 5 MPa, 6 MPa, 7 MPa, 8 MPa, 9 MPa or 10 MPa, etc. In this way, by setting an appropriate preset pressure, it is easy to open the pores of the catalyst support.

[0031] In one embodiment, the reaction time is between 10 min and 30 min. For example, the reaction time can be 10 min, 12 min, 15 min, 17 min, 20 min, 22 min, 25 min, 27 min, or 30 min, etc. In this way, by setting a suitable reaction time, it is convenient for aqua regia to react with the active metal in the pores of the catalyst support, so as to improve the dissolution rate and recovery rate of the active metal.

[0032] In one embodiment, the preset stirring speed is between 60 r / min and 200 r / min. For example, the preset stirring speed can be 60 r / min, 70 r / min, 80 r / min, 90 r / min, 100 r / min, 110 r / min, 120 r / min, 130 r / min, 140 r / min, 150 r / min, 160 r / min, 170 r / min, 180 r / min, 190 r / min, or 200 r / min, etc. By setting a suitable preset stirring speed, the active metal can be brought into more complete contact with the aqua regia, accelerating the reaction process between the aqua regia and the active metal and improving the recovery rate of the active metal.

[0033] In one embodiment, the method includes: S3, heating the hydrophobic catalyst and the aqua regia at a preset temperature. For example, after pressurizing the container to a preset pressure, the mixture of the hydrophobic catalyst and aqua regia can be heated and stirred simultaneously at a preset temperature to accelerate the reaction between the aqua regia and the active metal, thereby increasing the recovery rate of the active metal.

[0034] In one embodiment, the preset temperature is between 50°C and 130°C. For example, the preset temperature can be 50°C, 60°C, 70°C, 80°C, 90°C, 100°C, 110°C, 120°C, or 130°C, etc. By setting a suitable preset temperature, on the one hand, the activation energy of the reactants can be increased, thereby increasing the collision frequency and reaction rate; on the other hand, a suitable temperature can increase the kinetic energy of molecules and atoms, making it easier for reactant molecules to overcome the activation energy barrier, thus increasing the reaction rate; furthermore, since the chemical reaction between the active metal and aqua regia is an exothermic reaction, a suitable temperature can promote the reaction and improve the recovery rate of the active metal.

[0035] In one embodiment, the method includes: S4, performing multiple pressurization-depressurization operations on the mixture in the container until the active metal dissolves.

[0036] In other words, there are multiple preset time periods. Within each preset time period, the mixture in the container is first pressurized to the preset pressure. After the preset time period ends, the pressure in the container is reduced to normal pressure. In this way, the pores of the catalyst support can be repeatedly flushed, extending the reaction time between aqua regia and active metal, thereby further improving the recovery rate of active metal.

[0037] In one embodiment, the step of filtering the solution to obtain a filtrate includes: S13. Filter out the catalyst support in the solution to obtain the first filtrate; S14. The catalyst support is washed multiple times with hydrochloric acid and / or water to obtain a washing solution; S15. Mix the first filtrate and the washing solution to obtain the filtrate.

[0038] For example, after obtaining the solution, the catalyst support in the solution can be filtered out to obtain a first filtrate. Then, the catalyst support can be rinsed multiple times with hydrochloric acid and / or water. The washing solution is mixed with the first filtrate to obtain a filtrate. In this way, not only can the surface residue of the catalyst support be cleaned and the recovery rate of the active metal be improved, but also the introduction of new impurities can be avoided to improve the purity of the active metal.

[0039] In one embodiment, before reducing the active metal in the filtrate (S2), the method includes: (S5) heating the filtrate at a set temperature to remove nitrate and evaporating to concentrate it.

[0040] Here, by heating the filtrate at a set temperature, impurities such as nitrate and water can be removed, thereby increasing the concentration of active metals in the filtrate and achieving a high recovery rate of active metals.

[0041] In one embodiment, step S2, which involves reducing the active metal in the filtrate, includes: S21. Add ammonia to the filtrate, and after determining the pH value of the filtrate to the first set value, add a reducing agent.

[0042] Here, since the filtrate is highly acidic at this time, ammonia water can be added to neutralize the acidity and raise its pH value to the first preset value. This makes it easier for the reducing agent to reduce the active metal, resulting in a high recovery rate of the active metal.

[0043] In one embodiment, the reducing agent is at least one of methanol, formaldehyde, ethanol, acetone, and hydrazine hydrate. Using at least one of methanol, formaldehyde, ethanol, acetone, and hydrazine hydrate as the reducing agent not only provides strong reducing power but also introduces fewer impurities, resulting in high purity of recovered active metals.

[0044] In one embodiment, after reducing the active metal in the filtrate in step S2, the method includes step S6: filtering and drying the reduced active metal.

[0045] Here, vacuum filtration refers to using a vacuum pump to reduce the pressure of the filter bottle in order to achieve solid-liquid separation. In other words, it can better separate solid active metals from liquids, improve the separation efficiency of active metals, and finally dry the separated active metals at room temperature to obtain high-purity active metals.

[0046] In one exemplary embodiment, 100g of Pt / SDB hydrophobic catalyst, containing 2% platinum (mass fraction), was mixed with aqua regia at a preset volume ratio of 1:1. The pressure inside the container was then increased to 3 MPa, the preset stirring speed was 60 r / min, the preset temperature was 60℃, and the reaction time was 10 min. The pressure was then released, and this pressurization-depressurization operation was repeated three times. The solution was removed and the catalyst support was filtered off. The catalyst support was washed twice with 10% hydrochloric acid and once with deionized water. The first filtrate and washings were mixed. The filtrate was heated at a set temperature to remove nitrates and concentrate to 100 mL. Ammonia was added, and the pH was adjusted to 5.8. Then, hydrazine hydrate was slowly added as a reducing agent for reduction. Finally, the solution was filtered, washed with deionized water, and dried at room temperature to obtain powdered platinum black. The platinum content was detected using ICP-MS (inductively coupled plasma mass spectrometry). The results showed that the platinum recovery rate was 92.1%, and the platinum purity was 99.92%.

[0047] In one exemplary embodiment, 100g of Pt / SDB hydrophobic catalyst, containing 2% platinum (mass fraction), was mixed with aqua regia at a preset volume ratio of 1.5:1. The pressure inside the container was then increased to 10 MPa, the preset stirring speed was 200 r / min, the preset temperature was 80℃, and the reaction time was 10 min. The pressure was then released, and this pressurization-depressurization operation was repeated three times. The solution was removed and the catalyst support was filtered off. The catalyst support was washed twice with 10% hydrochloric acid and once with deionized water. The first filtrate and washings were mixed. The filtrate was heated at a set temperature to remove nitrates and concentrate to 100 mL. Ammonia was added and the pH was adjusted to 8. Then, hydrazine hydrate was slowly added as a reducing agent for reduction. Finally, the solution was filtered, washed with deionized water, and dried at room temperature to obtain powdered platinum black. The platinum content was determined using ICP-MS. The results showed that the platinum recovery rate was 92.4%, and the platinum purity was 99.89%.

[0048] The above description is merely a preferred embodiment of this application and is not intended to limit the application. Various modifications and variations can be made to this application by those skilled in the art. All modifications, equivalent substitutions, improvements, etc., within the spirit and principles of this application are included within the scope of protection of this application.

Claims

1. A method for recovering active metals from a hydrophobic catalyst, characterized in that, The hydrophobic catalyst comprises an active metal and a catalyst support, wherein the catalyst support has channels, and the active metal is located within the channels of the catalyst support. The method includes: A mixture is obtained by adding aqua regia and the hydrophobic catalyst in a predetermined volume ratio to a container; The container is pressurized to a preset pressure, and the mixture is stirred at a preset stirring speed within a preset reaction time. Then, the pressure in the container is reduced to normal pressure to obtain a solution. The solution is filtered to obtain a filtrate. The mixture in the container is subjected to multiple pressurization-depressurization operations until the active metal dissolves. The active metal in the filtrate is reduced.

2. The method according to claim 1, characterized in that, The preset volume ratio is the volume ratio of the aqua regia to the hydrophobic catalyst, and the preset volume ratio is between 1:1 and 3:

1.

3. The method according to claim 1, characterized in that, The preset pressure is between 3 MPa and 10 MPa; and / or, The reaction time is between 10 min and 30 min; and / or, The preset stirring speed is between 60 r / min and 200 r / min.

4. The method according to claim 1, characterized in that, The method includes heating the hydrophobic catalyst and the aqua regia at a preset temperature.

5. The method according to claim 4, characterized in that, The preset temperature is between 50°C and 130°C.

6. The method according to claim 1, characterized in that, Before reducing the active metal in the filtrate, the method includes: The filtrate is heated to remove nitrates and evaporated to concentrate it at a set temperature.

7. The method according to claim 1, characterized in that, The step of reducing the active metal in the filtrate includes: Ammonia is added to the filtrate, and after the pH value of the filtrate is determined to reach a first set value, a reducing agent is added.

8. The method according to claim 7, characterized in that, The reducing agent is at least one of methanol, formaldehyde, ethanol, acetone and hydrazine hydrate.

9. The method according to claim 1, characterized in that, The active metal is platinum, and the catalyst support is polystyrene-divinylbenzene.

10. The method according to claim 1, characterized in that, The step of filtering the solution to obtain a filtrate includes: The catalyst support in the solution is filtered out to obtain the first filtrate; The catalyst support was washed multiple times with hydrochloric acid and / or water to obtain a washing solution. The first filtrate and the washing solution are mixed to obtain the filtrate.

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