Method for measuring content of noble metal elements in automobile purification catalyst

Abstract

The invention provides a method for determining the content of precious metal elements in an automobile purification catalyst, and belongs to the technical field of analysis and detection. According to the method, a composite melting system composed of sodium peroxide, anhydrous sodium metaborate and sodium tungstate is constructed, an automobile purification catalyst sample is subjected to efficient melting decomposition, complete leaching of a melt is achieved in combination with a hydrochloric acid and tartaric acid composite acidification system, a tin-tellurium coprecipitation enrichment technology is introduced on the basis, and the purity of the automobile purification catalyst sample is improved. Trace precious metal elements such as platinum, palladium and rhodium are selectively precipitated and effectively enriched, and matrix interference is remarkably reduced; and then adding an indium internal standard solution and carrying out quantitative determination by adopting inductively coupled plasma emission spectrometry, thereby realizing high-sensitivity and high-accuracy analysis of the noble metal element. The method effectively solves the problems of incomplete sample decomposition, low precious metal recovery rate, serious matrix interference, poor detection result stability and the like in the prior art.

Description

Technical Field

[0001] This invention relates to the field of analytical testing technology, and in particular to a method for determining the content of precious metal elements in automotive purification catalysts. Background Technology

[0002] Vehicle exhaust emissions have become a significant source of air pollution. To reduce harmful gas emissions, automobiles are generally equipped with exhaust purification catalysts, whose core active components are typically precious metals such as platinum, palladium, and rhodium. These precious metals play an irreplaceable role in promoting the conversion of carbon monoxide, hydrocarbons, and nitrogen oxides. Due to the scarcity and high price of precious metal resources, their content in catalysts directly affects catalytic performance, production costs, and subsequent recycling value. Therefore, establishing an accurate, reliable method for determining the content of precious metal elements in automotive purification catalysts under complex matrix conditions has significant practical and application value. However, automotive purification catalysts typically use honeycomb ceramics, alumina, silicates, etc., as supports, resulting in dense structures and stable chemical properties. Precious metal elements exist in highly dispersed or solid-solution forms, and their content is often at trace or even ultra-trace levels, which poses considerable challenges to the complete decomposition and accurate determination of samples.

[0003] Existing technologies for determining the precious metal content in automotive purification catalysts mainly include wet acid dissolution, single melt decomposition combined with spectroscopic analysis, and direct spectroscopic detection. Traditional acid dissolution methods typically use aqua regia, hydrofluoric acid, or polyacid systems to digest the sample. However, these methods suffer from problems such as long digestion times, high operational risks, incomplete dissolution of some carriers, and unstable precious metal recovery rates. This is especially true when processing high-silicon and high-alumina matrix samples, where incomplete digestion or loss of precious metals is common. While single melt systems can improve sample decomposition to some extent, they often suffer from high melting temperatures, difficulty in extracting the melt, or the introduction of new matrix interference elements, affecting the accuracy of subsequent measurements. Furthermore, during spectroscopic analysis, the diverse and high-content matrix elements in the catalyst can easily lead to severe spectral interference and matrix effects during direct measurement, resulting in decreased detection sensitivity and poor repeatability, failing to meet the requirements of high-precision analysis.

[0004] Therefore, developing a determination method that can achieve complete sample decomposition, efficient enrichment of precious metals, and high-sensitivity detection technology has become an important direction for technological development in this field.

[0005] Therefore, this invention is proposed. Summary of the Invention

[0006] To address the aforementioned technical problems, this invention provides a method for determining the content of precious metal elements in automotive purification catalysts.

[0007] In order to achieve the objective of this invention, the following technical solution is adopted: This invention provides a method for determining the content of precious metal elements in automotive purification catalysts, comprising the following steps: S1: The catalyst sample is pretreated with a flux to obtain a melt; S2: The molten material is leached with an acidifying agent to obtain a treatment solution; S3: The treatment solution is enriched by precipitation of precious metal elements using the tin-tellurium co-precipitation method to obtain enriched precipitates; S4: Dissolve the enriched precipitate, add internal standard reagent and dilute to volume to obtain the test solution; S5: Perform spectral analysis on the solution to be tested, and calculate the content of precious metal elements using the calibration curve; The flux is a composite melting system consisting of sodium peroxide, anhydrous sodium metaborate, and sodium tungstate.

[0008] Furthermore, the mass ratio of sodium peroxide to anhydrous sodium metaborate is (3-6):1, and the amount of sodium tungstate added is 2%-10% of the total mass of the flux.

[0009] Furthermore, the acidifying agent is a composite solution of hydrochloric acid and tartaric acid, wherein the molar ratio of hydrochloric acid to tartaric acid is 1:1-3:1.

[0010] Furthermore, the tin-tellurium co-precipitation method in step S3 includes the following steps: First, add a tin salt solution to the treatment solution to control the pH of the solution within the range of 2.5 to 3.5; Then, slowly add the tellurium salt solution and react under stirring for 30-60 minutes; Then add the complexing agent and continue stirring for 20-40 minutes.

[0011] Furthermore, the tin salt solution is one or more of stannous chloride, stannous sulfate, or stannous nitrate; the tellurium salt solution is any one of sodium tellurite, potassium tellurite, or ammonium tellurite.

[0012] Furthermore, the complexing agent is one or more of ethylenediaminetetraacetic acid, tartaric acid, citric acid, or oxalic acid, and the amount of the complexing agent is 0.01%-0.10% of the total mass of the treatment solution, used to complex interfering element ions in the matrix.

[0013] Furthermore, the internal standard reagent is an indium internal standard solution, which is prepared by dissolving high-purity metallic indium in nitric acid to obtain an indium solution, and then acidifying and diluting it with hydrochloric acid.

[0014] Furthermore, the indium concentration in the indium internal standard solution is 1000 μg / mL.

[0015] Furthermore, in step S5, inductively coupled plasma atomic emission spectrometry is used to measure the solution to be tested.

[0016] The present invention also provides an application of the above-mentioned determination method in determining the content of precious metal elements in automotive purification catalysts.

[0017] The present invention has the following technical effects: (1) By constructing a composite melting system composed of sodium peroxide, anhydrous sodium metaborate and sodium tungstate, this invention achieves complete destruction and effective decomposition of the structure of automotive purification catalyst samples, fundamentally solving the problem that samples are difficult to completely dissolve due to the dense and chemically stable carrier materials in the prior art.

[0018] (2) Based on the complete decomposition and leaching of the sample, the present invention introduces the tin-tellurium coprecipitation enrichment technology and uses a complexing agent system to suppress the interference of matrix ions, thereby achieving highly selective enrichment and effective separation of noble metal elements, thus significantly reducing the interference of complex carrier materials on the detection process.

[0019] (3) This invention organically combines composite melting decomposition, composite acid leaching, tin-tellurium co-precipitation enrichment and internal standard-corrected inductively coupled plasma emission spectroscopy to construct a complete, systematic and highly repeatable precious metal detection technology route, which significantly improves the stability, operational consistency and engineering applicability of the entire analysis process. Detailed Implementation

[0020] To make the objectives, technical solutions, and advantages of this invention clearer, the technical solutions of this invention will be clearly and completely described below. Obviously, the described embodiments are only a part of the embodiments of this invention, and not all of them. Based on the embodiments of this invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of this invention.

[0021] Against the backdrop of increasingly stringent vehicle exhaust emission standards and ever-increasing environmental protection requirements, automotive purification catalysts, as important devices for reducing harmful gas emissions, mainly consist of precious metal elements such as platinum, palladium, and rhodium as their active components. These precious metals are not only costly but also directly affect the purification efficiency and service life of the catalyst. Therefore, accurate and stable determination of their content has become an important part of catalyst research and development, production, and quality control.

[0022] However, existing technologies still face many technical challenges in determining precious metal elements in automotive purification catalysts. First, automotive purification catalysts are typically made of ceramic honeycomb supports or composite materials mainly composed of alumina and silicates. These materials have a dense structure and stable chemical properties, and precious metal elements often exist in highly dispersed or solid-solution forms, with their content frequently at trace or even ultra-trace levels. This makes complete sample decomposition and effective release of precious metals extremely difficult.

[0023] Traditional wet acid digestion methods mainly rely on aqua regia, hydrofluoric acid, or mixed acid systems. These methods not only require high temperature and pressure conditions or prolonged heating, but also suffer from high operational risks, strong corrosiveness, uneven digestion, and large fluctuations in recovery rates. Especially in samples with high silica or high aluminum supports, incomplete decomposition, loss of precious metals, or secondary precipitation of some metals are prone to occur, leading to low measurement results or poor repeatability. Secondly, although single flux systems can disrupt the support structure and promote the release of precious metals to some extent, in practice, they often suffer from high melting temperatures, poor melt flowability, low leaching efficiency, and the introduction of new matrix interference elements, making it difficult to meet the requirements for accurate recovery and high repeatability. Thirdly, even if the sample is successfully dissolved, direct spectroscopic determination is hampered by the presence of large amounts of matrix elements such as aluminum, silicon, iron, calcium, and magnesium in the catalyst. These elements cause severe matrix interference, signal suppression, and spectral line overlap during spectroscopic determination, resulting in reduced sensitivity, poor result stability, and insufficient analytical limits for trace determination of precious metal elements. In addition, existing enrichment methods, such as single precipitation, extraction or adsorption enrichment, are cumbersome, have demanding operating conditions or insufficient selectivity, and precious metals are easily lost during the enrichment process. They cannot effectively solve the problem of accurate determination of low-content samples, thus limiting their practical application in the analysis of automotive purification catalysts.

[0024] To address the problems existing in the prior art, this invention proposes a systematic, reproducible, and easy-to-operate method for determining the content of precious metal elements in automotive purification catalysts. By combining melting decomposition, acid leaching, tin-tellurium co-precipitation enrichment, and internal standard-corrected spectral determination, this method effectively solves technical problems such as incomplete sample decomposition, severe matrix interference, low precious metal recovery rate, and poor determination stability.

[0025] The technical solution of this invention achieves complete sample dissolution through composite melting decomposition and acid leaching, effectively separates noble metal elements and removes matrix interference through tin-tellurium co-precipitation enrichment and interference suppression by complexing agents, and finally completes highly sensitive and stable quantitative analysis by combining internal standard calibrated spectroscopy. This completely solves the technical problems of incomplete sample decomposition, low noble metal recovery rate, severe matrix interference, and poor detection repeatability in existing technologies. Furthermore, the method of this invention is simple to operate, safe to operate, and widely applicable. It can achieve stable and reliable detection results even under trace noble metal content conditions, significantly improving analytical accuracy, recovery rate, and method repeatability. This provides an efficient, reliable, and widely applicable technical solution for the accurate determination of noble metal elements in automotive purification catalysts, and has significant practical significance and application value for catalyst quality control, performance evaluation, and resource recovery.

[0026] In a first aspect, the present invention provides a method for determining the content of precious metal elements in automotive purification catalysts, comprising the following steps: S1: The catalyst sample is pretreated with a flux to obtain a melt; S2: The molten material is leached with an acidifying agent to obtain a treatment solution; S3: The treatment solution is enriched by precipitation of precious metal elements using the tin-tellurium co-precipitation method to obtain enriched precipitates; S4: Dissolve the enriched precipitate, add internal standard reagent and dilute to volume to obtain the test solution; S5: Perform spectral analysis on the solution to be tested, and calculate the content of precious metal elements using the calibration curve; The flux is a composite melting system consisting of sodium peroxide, anhydrous sodium metaborate, and sodium tungstate.

[0027] In some embodiments, the mass ratio of sodium peroxide to anhydrous sodium metaborate is (3-6):1, and the amount of sodium tungstate added is 2%-10% of the total mass of the flux.

[0028] Specifically, this invention constructs a composite melting system composed of sodium peroxide, anhydrous sodium metaborate, and sodium tungstate. Sodium peroxide provides strong oxidizing power, oxidizing noble metal elements to more soluble valence states while simultaneously disrupting the ceramic support and oxide structure. Anhydrous sodium metaborate acts as a flux, lowering the melting temperature and improving the fluidity of the melt, allowing the melting system to fully contact the sample and enhancing reaction completeness. The addition of sodium tungstate not only enhances the stability of the melting system but also effectively prevents sample splashing or uneven local reactions during melting, ensuring the safety and uniformity of the entire sample decomposition process. Through this composite melting system, the sample can achieve complete decomposition under relatively mild and controllable conditions, allowing noble metal elements such as platinum, palladium, and rhodium to enter the subsequent processing solution in a stable and soluble form, laying a solid foundation for high recovery rate determination.

[0029] In some embodiments, the acidifying agent is a composite solution of hydrochloric acid and tartaric acid, wherein the molar ratio of hydrochloric acid to tartaric acid is 1:1 to 3:1.

[0030] In some embodiments, the tin-tellurium co-precipitation method in step S3 includes the following steps: First, add a tin salt solution to the treatment solution to control the pH of the solution within the range of 2.5 to 3.5; Then, slowly add the tellurium salt solution and react under stirring for 30-60 minutes; Then add the complexing agent and continue stirring for 20-40 minutes.

[0031] In the leaching process after sample melting and decomposition, this invention employs a hydrochloric acid and tartaric acid composite acidification system. Hydrochloric acid provides strong acid conditions to ensure metal dissolution, while tartaric acid stabilizes metal ions and inhibits their hydrolysis and secondary precipitation, thereby maximizing the leaching efficiency of precious metal elements. Subsequently, a tin-tellurium co-precipitation enrichment technique is introduced. By controlling the pH of the solution at 2.5-3.5 after the addition of tin salt, the precious metal forms selective precipitates with tin and tellurium in the system, while most matrix elements remain in solution and are separated. The slow addition of tellurium salt with thorough stirring, followed by the addition of a complexing agent to further complex interfering ions, not only improves the purity of the precious metal precipitation but also effectively reduces the interference of complex carriers on the detection process. In this way, precious metal elements are almost not lost during the enrichment process, significantly improving enrichment efficiency, thus enabling stable and accurate determination even under trace or micro-level conditions. By using complexing agents such as ethylenediaminetetraacetic acid, tartaric acid, citric acid, or oxalic acid to further suppress interfering ions, effective shielding of complex matrices is achieved, ensuring the selectivity and purity of enrichment precipitation.

[0032] In some embodiments, the tin salt solution is one or more of stannous chloride, stannous sulfate, or stannous nitrate; the tellurium salt solution is any one of sodium tellurite, potassium tellurite, or ammonium tellurite.

[0033] In some embodiments, the complexing agent is one or more of ethylenediaminetetraacetic acid, tartaric acid, citric acid, or oxalic acid, and the amount of the complexing agent is 0.01%-0.10% of the total mass of the treatment solution, used to complex interfering element ions in the matrix.

[0034] In some embodiments, the internal standard reagent is an indium internal standard solution, which is prepared by dissolving high-purity metallic indium in nitric acid to obtain an indium solution, and then acidifying and diluting it with hydrochloric acid.

[0035] In some embodiments, the indium concentration in the indium internal standard solution is 1000 μg / mL.

[0036] In some embodiments, in step S5, inductively coupled plasma atomic emission spectrometry is used to measure the solution to be tested.

[0037] In the determination stage, this invention employs inductively coupled plasma atomic emission spectrometry (ICP-AES) with internal standard correction. The addition of indium internal standard solution allows for real-time correction of fluctuations in atomization efficiency, changes in plasma conditions, and instrument drift, thereby further improving the accuracy and repeatability of the measurement data. This method achieves high sensitivity, low detection limit, and wide linear range determination of precious metal elements in automotive purification catalysts, significantly improving data inconsistencies caused by matrix interference, unstable recovery rates, or differences in operating conditions in traditional methods. In terms of overall technical design, this application not only systematically optimizes key parameters such as the flux composition ratio, acidification system molar ratio, co-precipitation conditions, and complexing agent dosage, but also organically combines sample pretreatment with high-precision spectroscopic analysis, achieving full-process control from sample decomposition and enrichment to detection, ensuring the reliability, stability, and repeatability of the method. Furthermore, this method is highly safe to operate, requiring no high-pressure sealed equipment or large amounts of corrosive reagents. The experimental conditions are controllable, suitable for conventional laboratory operating environments, and possess good engineering scalability and practicality. It can be widely applied to quality control in automotive purification catalyst production, R&D evaluation, and precious metal resource recovery management.

[0038] Secondly, the present invention also provides an application of the above-described determination method in determining the content of precious metal elements in automotive purification catalysts.

[0039] The following is a detailed explanation using specific embodiments: Example 1 Step 1: Catalyst Melting Pretreatment Weigh 0.2g of automotive three-way catalyst powder and place it in a nickel crucible.

[0040] Add 4.0g of composite flux, which includes: Sodium peroxide 3.0g 1.0g of anhydrous sodium metaborate Sodium tungstate 0.08 g (2% of the total flux) Place the nickel crucible in a muffle furnace, heat to 750°C, and maintain the temperature for 30 minutes until completely melted. Use nickel clamps to hold the crucible during melting to prevent it from tipping over. After melting, allow it to cool naturally to room temperature to obtain a homogeneous melt.

[0041] Step 2: Acidification Leaching Transfer the cooled melt to a 250mL beaker, slowly add 50mL of hydrochloric acid-tartaric acid composite solution (hydrochloric acid to tartaric acid molar ratio 1:1), and gently stir with a glass rod.

[0042] Place the beaker in an 80°C water bath and heat for 30 minutes, stirring every 5 minutes to ensure the melt is completely dissolved and transferred to the solution.

[0043] After heating, the solution was filtered through a 0.45μm filter membrane to obtain a transparent treatment solution.

[0044] Step 3: Tin-tellurium co-precipitation enrichment Add tin salt: Add 10 mL of stannous chloride solution (0.5 mol / L) to the treatment solution, adjust the pH to 2.5 with dilute hydrochloric acid, and keep the mixture magnetically stirred.

[0045] Add tellurium salt: Slowly add 20 mL of sodium tellurite solution (0.05 mol / L) and stir for 30 minutes at room temperature to allow the noble metal ions to form a co-precipitate with Sn-Te.

[0046] Complexing interfering ions: Add 0.01% (total mass of the treatment solution) of ethylenediaminetetraacetic acid solution and continue stirring for 20 minutes to complex any interfering metal ions that may be present in the solution.

[0047] After precipitation, centrifuge at 3500 rpm for 10 minutes, discard the supernatant, and transfer the precipitate to a 50 mL beaker for later use.

[0048] Step 4: Precipitate Dissolution and Internal Standard Addition Add 10 mL of hydrochloric acid to the precipitate, heat to 60 °C to dissolve the precipitate, and then dilute to 50 mL with deionized water.

[0049] Add 2 mL of indium internal standard solution (1000 μg / mL), shake well, and obtain the test solution.

[0050] Step 5: Spectroscopic Measurement The test solution was transferred to the sample vial of the ICP-OES instrument. A standard curve was set, and the emission intensity of the noble metal elements was measured. The content of noble metal elements such as platinum, palladium, and rhodium in the automotive purification catalyst was calculated using the calibration curve. After the inductively coupled plasma atomic emission spectrometer (ICP-OES) stabilized, the working curve was read according to the analytical conditions of the ICP-OES instrument. The working curve was plotted with the mass concentration of platinum, palladium, and rhodium on the x-axis and the corresponding emission intensity on the y-axis.

[0051] Example 2 Step 1: Catalyst Melting Pretreatment Weigh 0.2g of automotive three-way catalyst powder and place it in a nickel crucible.

[0052] Add 4.0g of composite flux, which includes: Sodium peroxide 3.0g 0.5g of anhydrous sodium metaborate (sodium peroxide:sodium metaborate mass ratio is 6:1) Sodium tungstate 0.4g (10% of the total flux) Place the crucible in a muffle furnace, heat to 750°C, and maintain the temperature for 30 minutes until completely melted. Use nickel clamps to hold the crucible during melting to prevent tipping. After melting, allow it to cool naturally to room temperature to obtain a homogeneous melt.

[0053] Step 2: Acidification Leaching Transfer the cooled melt to a 250mL beaker, slowly add 50mL of hydrochloric acid-tartaric acid composite solution (hydrochloric acid to tartaric acid molar ratio 3:1), and gently stir with a glass rod.

[0054] Place the beaker in an 80°C water bath and heat for 30 minutes, stirring every 5 minutes to ensure the melt is completely dissolved and transferred to the solution.

[0055] After heating, the solution was filtered through a 0.45μm filter membrane to obtain a transparent treatment solution.

[0056] Step 3: Tin-tellurium co-precipitation enrichment Add tin salt: Add 10 mL of stannous chloride solution (0.5 mol / L) to the treatment solution, adjust the pH to 3.5 with dilute hydrochloric acid, and keep the mixture magnetically stirred.

[0057] Add tellurium salt: Slowly add 20 mL of sodium tellurite solution (0.05 mol / L) and stir for 60 minutes at room temperature to allow the noble metal ions to form a co-precipitate with Sn-Te.

[0058] Complexing interfering ions: Add a mixed solution of EDTA, tartaric acid, citric acid and oxalic acid, at a volume of 0.10% of the total mass of the treatment solution, and continue stirring for 40 minutes.

[0059] After precipitation, centrifuge at 3500 rpm for 10 minutes, discard the supernatant, and transfer the precipitate to a 50 mL beaker for later use.

[0060] Step 4: Precipitate Dissolution and Internal Standard Addition Add 10 mL of hydrochloric acid to the precipitate, heat to 60 °C to dissolve the precipitate, and then dilute to 50 mL with deionized water.

[0061] Add 2 mL of indium internal standard solution (1000 μg / mL), shake well, and obtain the test solution.

[0062] Step 5: Spectroscopic Measurement The test solution was transferred to the sample vial of the ICP-OES instrument, a standard curve was set, and the emission intensity of the precious metal elements was measured. The content of precious metal elements such as platinum, palladium, and rhodium in the automotive purification catalyst was calculated using the calibration curve.

[0063] Example 3 Step 1: Catalyst Melting Pretreatment Weigh 0.2g of automotive three-way catalyst powder and place it in a nickel crucible.

[0064] Add 4.0g of composite flux, which includes: Sodium peroxide 3.0g 0.667 g of anhydrous sodium metaborate (sodium peroxide:sodium metaborate mass ratio approximately 4.5:1) Sodium tungstate 0.24g (6% of the total flux) Place the crucible in a muffle furnace, heat to 750°C, and maintain the temperature for 30 minutes until completely melted. Use nickel clamps to hold the crucible during melting to prevent tipping. After melting, allow it to cool naturally to room temperature to obtain a homogeneous melt.

[0065] Step 2: Acidification Leaching Transfer the cooled melt to a 250 mL beaker, slowly add 50 mL of hydrochloric acid-tartaric acid composite solution (hydrochloric acid to tartaric acid molar ratio 2:1), and gently stir with a glass rod.

[0066] Place the beaker in an 80°C water bath and heat for 30 minutes, stirring every 5 minutes to ensure the melt is completely dissolved and transferred to the solution.

[0067] After heating, the solution was filtered through a 0.45μm filter membrane to obtain a transparent treatment solution.

[0068] Step 3: Tin-tellurium co-precipitation enrichment Add tin salt: Add 10 mL of stannous chloride solution (0.5 mol / L) to the treatment solution, adjust the pH to 3.0 with dilute hydrochloric acid, and keep the mixture magnetically stirred.

[0069] Add tellurium salt: Slowly add 20 mL of sodium tellurite solution (0.05 mol / L) and stir at room temperature for 45 minutes to allow the noble metal ions to form a co-precipitate with Sn-Te.

[0070] Complexing interfering ions: Add a mixed solution of EDTA and citric acid, the amount of which is 0.05% of the total mass of the treatment solution, and continue stirring for 30 minutes.

[0071] After precipitation, centrifuge at 3500 rpm for 10 minutes, discard the supernatant, and transfer the precipitate to a 50 mL beaker for later use.

[0072] Step 4: Precipitate Dissolution and Internal Standard Addition Add 10 mL of hydrochloric acid to the precipitate, heat to 60 °C to dissolve the precipitate, and then dilute to 50 mL with deionized water.

[0073] Add 2 mL of indium internal standard solution (1000 μg / mL), shake well, and obtain the test solution.

[0074] Step 5: Spectroscopic Measurement The test solution was transferred to the sample vial of the ICP-OES instrument, a standard curve was set, and the emission intensity of the precious metal elements was measured. The content of precious metal elements such as platinum, palladium, and rhodium in the automotive purification catalyst was calculated using the calibration curve.

[0075] The final test results are shown in Table 1 below.

[0076] Table 1 Test Results The above results demonstrate that this method can stably and accurately determine the contents of platinum, palladium, and rhodium in the catalyst under different parameter conditions. Among them, the intermediate parameter combination used in Example 3 showed the lowest relative standard deviation and the highest recovery rate, indicating that the method has the best precision and accuracy under this parameter combination.

[0077] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, and not to limit them; although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some or all of the technical features; and these modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the technical solutions of the embodiments of the present invention.

Claims

1. A method for determining the content of precious metal elements in automotive purification catalysts, characterized in that, Includes the following steps: S1: The catalyst sample is pretreated with a flux to obtain a melt; S2: The molten material is leached with an acidifying agent to obtain a treatment solution; S3: The treatment solution is enriched by precipitation of precious metal elements using the tin-tellurium co-precipitation method to obtain enriched precipitates; S4: Dissolve the enriched precipitate, add internal standard reagent and dilute to volume to obtain the test solution; S5: Perform spectral analysis on the solution to be tested, and calculate the content of precious metal elements using the calibration curve; The flux is a composite melting system consisting of sodium peroxide, anhydrous sodium metaborate, and sodium tungstate.

2. The method for determining the content of precious metal elements in an automotive purification catalyst according to claim 1, characterized in that, The mass ratio of sodium peroxide to anhydrous sodium metaborate is (3-6):1, and the amount of sodium tungstate added is 2%-10% of the total mass of the flux.

3. The method for determining the content of precious metal elements in an automotive purification catalyst according to claim 1, characterized in that, The acidifying agent is a composite solution of hydrochloric acid and tartaric acid, wherein the molar ratio of hydrochloric acid to tartaric acid is 1:1-3:

1.

4. The method for determining the content of precious metal elements in an automotive purification catalyst according to claim 1, characterized in that, The tin-tellurium co-precipitation method in step S3 includes the following steps: First, add a tin salt solution to the treatment solution to control the pH of the solution within the range of 2.5 to 3.5; Then, slowly add the tellurium salt solution and react under stirring for 30-60 minutes; Then add the complexing agent and continue stirring for 20-40 minutes.

5. The method for determining the content of precious metal elements in an automotive purification catalyst according to claim 4, characterized in that, The tin salt solution is one or more of stannous chloride, stannous sulfate, or stannous nitrate; the tellurium salt solution is any one of sodium tellurite, potassium tellurite, or ammonium tellurite.

6. The method for determining the content of precious metal elements in an automotive purification catalyst according to claim 4, characterized in that, The complexing agent is one or more of ethylenediaminetetraacetic acid, tartaric acid, citric acid, or oxalic acid. The amount of the complexing agent is 0.01%-0.10% of the total mass of the treatment solution, and it is used to complex interfering element ions in the matrix.

7. The method for determining the content of precious metal elements in an automotive purification catalyst according to claim 4, characterized in that, The internal standard reagent is an indium internal standard solution, which is prepared by dissolving high-purity metallic indium in nitric acid to obtain an indium solution, and then acidifying and diluting it with hydrochloric acid.

8. The method for determining the content of precious metal elements in an automotive purification catalyst according to claim 7, characterized in that, The indium concentration in the indium internal standard solution is 1000 μg / mL.

9. The method for determining the content of precious metal elements in an automotive purification catalyst according to claim 1, characterized in that, In step S5, inductively coupled plasma atomic emission spectrometry is used to measure the solution to be tested.

10. The application of the determination method as described in any one of claims 1-9 in determining the content of precious metal elements in automotive purification catalysts.

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