Methods for determining precious metal content

Abstract

The present invention relates to a method for determining the content of precious metal in a precious metal compound solution or a precious metal compound solid, comprising crystallizing the precious metal salt, removing crystal water, and then weighing and calculating, wherein the precious metal is a platinum group element, preferably one of Pt, Pd or Rh, and more preferably Pd. The method of the present invention has the advantages of high analysis accuracy, simple analysis process, easy operation, short analysis cycle, less reagents used, less equipment investment, etc., and can be widely used in analysis for purposes such as metal settlement, precise control and process control.

Description

Technical Field

[0001] The present invention relates to a method for measuring the content of precious metals, and in particular to a method for measuring the content of precious metals in a precious metal compound solution or a precious metal compound solid. Background Art

[0002] Precious metal elements such as platinum (Pt), palladium (Pd), rhodium (Rh) and other platinum group elements are widely used as important catalysts in the exhaust purification devices of gasoline and diesel engines of vehicles. In the application process, high-purity solutions of precious metal compounds are usually used as raw materials. Since the price of precious metal compounds is very high, it is necessary to determine the precise precious metal content of these solutions to determine the selling price of the solutions. At the same time, it is also necessary to accurately control the precious metal content and process control in the production and use of precious metal compounds and solutions. Precious metal compounds can also be provided in the form of crystals or solids. These crystals may change the crystal water content during storage or the water content of the precious metal compound solids may change due to water absorption during storage, resulting in the precious metal content being inconsistent with the nominal value. In this case, it is also necessary to accurately determine the precious metal content of the precious metal crystals or solids.

[0003] Traditional analysis methods mainly include gravimetric analysis and instrumental analysis.

[0004] The main steps of the traditional gravimetric analysis method are: weighing - denitrification - complexation (for example, complexation with dibutyl ketone oxime) / reduction (for example, reaction with hydrazines) - filtration - ashing - hydrogen reduction - weighing calculation. This method has high analytical accuracy, but the analysis process is complicated, the requirements for operators are high, and more reagents are used, and the analysis cycle is long (about 3 to 4 working days).

[0005] The instrumental analysis method includes, for example, inductively coupled plasma optical emission spectroscopy (ICP-OES) and spectrophotometry.

[0006] The main steps of the ICP-OES method are: ICP-OES equipment preheating-instrument calibration-sample preparation (weighing dilution)-instrument testing-calculation. The analysis process of the ICP-OES method is simple and the cycle is short, but the analysis accuracy is insufficient, the measurement error is about 5%, and the price of the analysis equipment is relatively high, so it is mainly used for internal control with low requirements for analysis accuracy. For example, CN102023154A discloses a method for determining the palladium content in a palladium-carbon catalyst, including weighing about 0.15g of sample in a beaker, adding perchloric acid and a certain proportion of hydrochloric acid and nitric acid, covering the watch glass and heating on an electric hot plate until the white smoke disappears, the solution is clear, and about 0.15g of activated carbon powder is added at the same time, perchloric acid and a certain proportion of hydrochloric acid and nitric acid are added, blank solution and standard solution are prepared, and analyzed by a plasma emission spectrometer.

[0007] CN102954942A discloses a method for determining palladium content by spectrophotometry, including preparing a test solution and a standard solution, measuring the absorbance A of the test solution at a wavelength of 635nm; making a standard curve according to the palladium standard solution of different concentrations and the corresponding absorbance, calculating the slope k and intercept b of the standard curve regression equation; and calculating the palladium amount according to the equation. This method requires the preparation of a standard solution and a standard curve, the procedure is cumbersome, and the accuracy is not high.

[0008] Therefore, there is a need in the art for a method that can quickly, reliably and accurately determine the content of precious metals. Summary of the invention

[0009] The object of the present invention is to provide a method for rapidly, reliably and accurately determining the precious metal content in a precious metal compound aqueous solution or a precious metal compound solid.

[0010] The object is achieved by a method for determining the precious metal content in a precious metal compound aqueous solution, wherein the precious metal compound is one of a precious metal halide salt, a precious metal nitrate, a precious metal carboxylate, an inorganic precious metal acid or an inorganic precious metal acid ammonium salt, and the method comprises:

[0011] (i) If the noble metal compound is a noble metal halide salt, the noble metal halide salt in the noble metal halide salt aqueous solution is evaporated and crystallized to remove the crystal water, and then the weight of the obtained anhydrous noble metal halide salt is weighed to calculate the noble metal content according to the following formula:

[0012]

[0013] (ii) If the noble metal compound is a noble metal nitrate or a noble metal carboxylate, the noble metal nitrate or noble metal carboxylate in the noble metal nitrate or noble metal carboxylate aqueous solution is completely converted into a noble metal halide salt, the noble metal halide salt is evaporated and crystallized, the crystal water is removed, and then the weight of the obtained anhydrous noble metal halide salt is weighed, and the noble metal content is calculated according to the following formula:

[0014]

[0015] (iii) If the noble metal compound is an inorganic noble metal acid or an inorganic noble metal acid ammonium salt, the inorganic noble metal acid or inorganic noble metal acid ammonium salt aqueous solution is evaporated to dryness, and further heated until the inorganic noble metal acid or inorganic noble metal acid ammonium salt is completely decomposed into a single noble metal substance, and then the weight of the resulting single noble metal substance is weighed, and the noble metal content is calculated according to the following formula:

[0016]

[0017] Wherein Wt in each formula represents weight, and M represents molar mass.

[0018] The object of the present invention is also achieved by a method for determining the precious metal content in a precious metal compound solid, wherein the precious metal compound is one of a precious metal halide salt, a precious metal nitrate, a precious metal carboxylate, an inorganic precious metal acid or an inorganic precious metal acid ammonium salt, and the method comprises:

[0019] (i) If the noble metal compound is a noble metal halide salt, the possible crystal water or absorbed water is removed from the noble metal halide salt solid, and then the weight of the obtained anhydrous noble metal halide salt is weighed, and the content of the noble metal is calculated according to the following formula:

[0020]

[0021] (ii) If the noble metal compound is a noble metal nitrate or a noble metal carboxylate, the noble metal nitrate or noble metal carboxylate solid is dissolved in water to obtain a noble metal nitrate or noble metal carboxylate aqueous solution, the noble metal nitrate or noble metal carboxylate in the aqueous solution is converted into a noble metal halide salt and the noble metal halide salt is evaporated and crystallized; the crystal water is removed from the noble metal halide salt crystals, and then the weight of the obtained anhydrous noble metal halide salt is weighed, and the content of the noble metal is calculated according to the following formula:

[0022]

[0023] (iii) If the noble metal compound is an inorganic noble metal acid or an inorganic noble metal acid ammonium salt, the inorganic noble metal acid or inorganic noble metal acid ammonium salt solid is heated until it is completely decomposed into a single noble metal substance, and then the weight of the resulting single noble metal substance is weighed to calculate the noble metal content according to the following formula:

[0024]

[0025] Wherein Wt in each formula represents weight, and M represents molar mass.

[0026] The purity of the precious metal compound in the precious metal compound solution suitable for use in the present invention is usually very high, and is substantially free of other impurities. The purity may be, for example, greater than 99.95% by weight. DETAILED DESCRIPTION

[0027] In a first aspect of the present invention, the present invention relates to a method for determining the precious metal content in an aqueous solution of a precious metal compound, wherein the precious metal compound is one of a precious metal halide salt, a precious metal nitrate, a precious metal carboxylate, an inorganic precious metal acid or an inorganic precious metal acid ammonium salt, the method comprising:

[0028] (i) If the noble metal compound is a noble metal halide salt, the noble metal halide salt in the noble metal halide salt aqueous solution is evaporated and crystallized to remove the crystal water, and then the weight of the obtained anhydrous noble metal halide salt is weighed to calculate the noble metal content according to the following formula:

[0029]

[0030] (ii) If the noble metal compound is a noble metal nitrate or a noble metal carboxylate, the noble metal nitrate or noble metal carboxylate in the noble metal nitrate or noble metal carboxylate aqueous solution is completely converted into a noble metal halide salt, the noble metal halide salt is evaporated and crystallized, the crystal water is removed, and then the weight of the obtained anhydrous noble metal halide salt is weighed, and the noble metal content is calculated according to the following formula:

[0031]

[0032] (iii) If the noble metal compound is an inorganic noble metal acid or an inorganic noble metal acid ammonium salt, the inorganic noble metal acid or inorganic noble metal acid ammonium salt aqueous solution is evaporated to dryness, and further heated until the inorganic noble metal acid or inorganic noble metal acid ammonium salt is completely decomposed into a single noble metal substance, and then the weight of the resulting single noble metal substance is weighed, and the noble metal content is calculated according to the following formula:

[0033]

[0034] Wherein Wt in each formula represents weight, and M represents molar mass.

[0035] The noble metal to be measured may be a platinum group element, preferably one of Pt, Pd or Rh, more preferably Pd.

[0036] The noble metal halide salt is one of chloride, bromide or iodide salts, more preferably one of chloride salts or bromide salts, more preferably one of chloride salts, such as one of platinum chloride, palladium chloride or rhodium chloride.

[0037] The noble metal nitrate is one of platinum nitrate, palladium nitrate or rhodium nitrate.

[0038] The noble metal carboxylate is selected from noble metal C1-C 20 One of the carboxylates, preferably selected from noble metal C2-C 10 One of the carboxylates, most preferably one of the noble metal acetates or noble metal octanoates.

[0039] The inorganic noble metal acid or inorganic noble metal acid ammonium salt is one of inorganic halogenated noble metal acids or inorganic halogenated noble metal acid ammonium salts, preferably one of inorganic chlorinated noble metal acids or inorganic chlorinated noble metal acid ammonium salts, or inorganic brominated noble metal acids or inorganic brominated noble metal acid ammonium salts; more preferably one of chloroplatinic acid or ammonium chloroplatinate, bromoplatinic acid or ammonium bromoplatinate, chloropalladic acid or ammonium chloropalladic acid, bromopalladic acid or ammonium bromopalladic acid, chlororhodic acid or ammonium chlororhodic acid, bromorhodic acid or ammonium bromorhodic acid; most preferably one of chloroplatinic acid or ammonium chloroplatinate, bromoplatinic acid or ammonium bromoplatinate.

[0040] When the noble metal salt is a nitrate or a carboxylate, the nitrate or carboxylate of the noble metal is unstable and is easily decomposed during the heating process, thereby causing the measurement accuracy to deteriorate. Therefore, in an embodiment of the present invention, the nitrate or carboxylate is converted into a halide salt before crystallization. The method of converting the nitrate or carboxylate into a halide salt is known in the prior art, for example, adding a sufficient amount of concentrated hydrohalic acid to the solution, and then removing NO3 - or carboxylate, thereby completely converting the noble metal nitrate or noble metal carboxylate into a noble metal halide salt. In this article, the meaning of the term "sufficient amount" is well known to those skilled in the art, and means an amount of concentrated hydrohalic acid sufficient to convert all nitrates or carboxylates into halide salts, for example, a molar ratio of hydrohalic acid to noble metal is greater than or equal to 10:1, preferably greater than or equal to 30:1, and more preferably greater than or equal to 50:1.

[0041] The hydrohalic acid is selected from one of hydrochloric acid, hydrobromic acid or hydroiodic acid, preferably selected from one of hydrochloric acid or hydrobromic acid, and most preferably selected from hydrochloric acid.

[0042] NO3 - The removal of the carboxylate group can be carried out under boiling conditions, and the removal time can be, for example, 0.5 to 3 hours, preferably 1 to 2 hours. Then, the obtained halide salt is evaporated to dryness to crystallize it. Then, the crystallization water is removed and the weight of the obtained anhydrous noble metal halide salt is weighed, and the noble metal content is calculated according to the following formula:

[0043]

[0044] Where Wt represents weight and M represents molar mass.

[0045] In the case where the noble metal compound is a noble metal halide salt, the method includes crystallizing the noble metal halide salt; or when the noble metal salt is a noble metal nitrate or a noble metal carboxylate, the method includes crystallizing the obtained noble metal halide salt after converting the noble metal nitrate or noble metal carboxylate into a noble metal halide salt. Suitable crystallization methods are known to those skilled in the art, including, for example, evaporating the solvent to dryness. During the evaporation of the solvent, the solution needs to be heated. Excessive temperature may cause the solution to boil and splash, resulting in sample loss, thereby reducing the final analysis accuracy. Therefore, preferably, the crystallization is carried out at a lower temperature, such as 40 to 100°C, preferably 50 to 90°C, more preferably 60°C to 80°C, for example 70°C. There is no particular restriction on the crystallization time, as long as the solution is finally evaporated to dryness.

[0046] After crystallization, a precious metal halide salt containing water of crystallization is obtained. Since the precious metal halide salt containing water of crystallization is unstable under heating conditions, it may lose part of the water of crystallization during the heating process during crystallization. If the water of crystallization is not completely removed, this will affect the accuracy of the final measurement result. Therefore, in the method of the present invention, after crystallization, the water of crystallization of the obtained crystal is completely removed. The removal of water of crystallization should be carried out at a temperature higher than the removal temperature of water of crystallization. The removal temperature of water of crystallization of precious metal halide salt crystals is known in the art and can be learned from literature. In addition, the actual removal temperature of water of crystallization should not be too high, because if it is too high, the precious metal halide salt may decompose, thereby affecting the measurement accuracy. Therefore, the actual removal temperature of water of crystallization cannot be higher than the decomposition temperature of the precious metal halide salt. The decomposition temperature of precious metal halide salts is also known to those skilled in the art and can be learned from various literature. For example, the removal temperature of water of crystallization can be 120°C to 500°C, preferably 160°C to 350°C, and more preferably 180°C to 250°C. The end point of the removal of the crystal water is based on the final reaching of a constant weight. After the crystal water is removed, the obtained product can be cooled to room temperature in a desiccator, for example, and then accurately weighed. The weighing can be performed using an analytical balance.

[0047] After weighing, the precious metal content in the precious metal salt solution is calculated from the weighing result. Taking palladium nitrate (if converted into palladium chloride before crystallization) or palladium chloride as an example, the Pd content is calculated according to the following formula:

[0048]

[0049] In the case of (iii), the inorganic noble metal acid or the inorganic noble metal acid ammonium salt must be carried out under conditions sufficient to be converted into a metal element. These conditions are known to those skilled in the art, for example, from various chemical encyclopedias. For example, chloroplatinic acid or ammonium chloroplatinate decomposes at low temperatures (<500° C.) to generate a mixture of PtCl4, PtO2 and Pt, which makes it difficult to quantify the precious metal. However, chloroplatinic acid or ammonium chloroplatinate can achieve the generation of Pt element even in an air atmosphere at high temperatures (>550° C., for example, it can be quickly decomposed at 820° C.), which is very beneficial for the accurate measurement of precious metals. Therefore, in the present invention, chloroplatinic acid or ammonium chloroplatinate is heated at high temperatures to completely decompose into a platinum element.

[0050] In a preferred embodiment of the present invention, a method for determining the precious metal content in a precious metal nitrate or precious metal carboxylate aqueous solution is provided, comprising:

[0051] a) adding a sufficient amount of concentrated hydrohalic acid to the solution and then heating it under boiling conditions to remove NO3 - or carboxylate, thereby completely converting the noble metal nitrate or noble metal carboxylate into a noble metal halide salt;

[0052] b) crystallizing the halide salt;

[0053] c) removing water of crystallization; and

[0054] d) Weigh the weight of the obtained anhydrous noble metal halide salt and calculate the content of the noble metal according to the following formula:

[0055]

[0056] Where Wt represents weight and M represents molar mass.

[0057] More preferably, in the embodiment described above, concentrated hydrochloric acid is used as concentrated hydrohalic acid. Furthermore, in step ii), the chloride salt is preferably crystallized by evaporation.

[0058] In a second aspect of the present invention, the present invention relates to a method for determining the precious metal content in a precious metal compound solid, wherein the precious metal compound is one of a precious metal halide salt, a precious metal nitrate, a precious metal carboxylate, an inorganic precious metal acid or an inorganic precious metal acid ammonium salt, the method comprising:

[0059] (i) If the noble metal compound is a noble metal halide salt, the possible crystal water or absorbed water is removed from the noble metal halide salt solid, and then the weight of the obtained anhydrous noble metal halide salt is weighed, and the content of the noble metal is calculated according to the following formula:

[0060]

[0061] (ii) If the noble metal compound is a noble metal nitrate or a noble metal carboxylate, the noble metal nitrate or noble metal carboxylate solid is dissolved in water to obtain a noble metal nitrate or noble metal carboxylate aqueous solution, the noble metal nitrate or noble metal carboxylate in the aqueous solution is converted into a noble metal halide salt and the noble metal halide salt is evaporated and crystallized; the crystal water is removed from the noble metal halide salt crystals, and then the weight of the obtained anhydrous noble metal halide salt is weighed, and the content of the noble metal is calculated according to the following formula:

[0062]

[0063] (iii) If the noble metal compound is an inorganic noble metal acid or an inorganic noble metal acid ammonium salt, the inorganic noble metal acid or inorganic noble metal acid ammonium salt solid is heated until it is completely decomposed into a single noble metal substance, and then the weight of the resulting single noble metal substance is weighed to calculate the noble metal content according to the following formula:

[0064]

[0065] Wherein Wt in each formula represents weight, and M represents molar mass.

[0066] The noble metal halide salt is one of chloride, bromide or iodide salts, more preferably one of chloride salts or bromide salts, more preferably one of chloride salts, such as one of platinum chloride, palladium chloride or rhodium chloride.

[0067] The noble metal nitrate is one of platinum nitrate, palladium nitrate or rhodium nitrate.

[0068] The noble metal carboxylate is selected from noble metal C1-C 20 One of the carboxylates, preferably selected from noble metal C2-C 10 One of the carboxylates, most preferably one of the noble metal acetates or noble metal octanoates.

[0069] The inorganic noble metal acid or inorganic noble metal acid ammonium salt is one of inorganic halogenated noble metal acids or inorganic halogenated noble metal acid ammonium salts, preferably one of inorganic chlorinated noble metal acids or inorganic chlorinated noble metal acid ammonium salts, or inorganic brominated noble metal acids or inorganic brominated noble metal acid ammonium salts; more preferably one of chloroplatinic acid or ammonium chloroplatinate, bromoplatinic acid or ammonium bromoplatinate, chloropalladic acid or ammonium chloropalladic acid, bromopalladic acid or ammonium bromopalladic acid, chlororhodic acid or ammonium chlororhodic acid, bromorhodic acid or ammonium bromorhodic acid; most preferably one of chloroplatinic acid or ammonium chloroplatinate, bromoplatinic acid or ammonium bromoplatinate.

[0070] In the case of (i) and (ii), the process conditions for removing the crystallization water are as described above in the first aspect.

[0071] As described above, since the precious metal nitrate or carboxylate is unstable, it is easy to decompose in the process of removing the crystal water, which leads to the deterioration of the measurement accuracy. Therefore, in an embodiment of the present invention, before removing the crystal water, the precious metal nitrate or precious metal carboxylate is dissolved in, for example, deionized water, and then converted into a precious metal halide salt. The method for converting precious metal nitrate or precious metal carboxylate into precious metal halide is as described above in the first aspect. After conversion to precious metal halide salt, the content of precious metal halide salt can be determined according to the method described in the first aspect of the present invention, that is, the halide salt in the solution is crystallized, the crystal water is removed, and then weighed and calculated. The crystallization conditions and the conditions for removing the crystal water are as described above in the first aspect.

[0072] In the case of (iii), the inorganic noble metal acid or the inorganic noble metal acid ammonium salt must be carried out under conditions sufficient to be converted into a metal element. These conditions are known to those skilled in the art, for example, from various chemical encyclopedias. For example, chloroplatinic acid or ammonium chloroplatinate decomposes at low temperatures (<500° C.) to generate a mixture of PtCl4, PtO2 and Pt, which makes it difficult to quantify the precious metal. However, chloroplatinic acid or ammonium chloroplatinate can achieve the generation of Pt element even in an air atmosphere at high temperatures (>550° C., for example, it can be quickly decomposed at 820° C.), which is very beneficial for the accurate measurement of precious metals. Therefore, in the present invention, chloroplatinic acid or ammonium chloroplatinate is heated at high temperatures to completely decompose into a platinum element.

[0073] Therefore, in a preferred embodiment of the present invention, the present invention relates to a method for determining the precious metal content in a precious metal nitrate or precious metal carboxylate solid, comprising:

[0074] a) dissolving the noble metal nitrate or noble metal carboxylate solid in water to obtain a solution;

[0075] b) adding a sufficient amount of concentrated hydrohalic acid to the solution and then heating it under boiling conditions to remove NO3 - or carboxylate, thereby completely converting the noble metal nitrate or noble metal carboxylate into a noble metal halide salt;

[0076] c) crystallizing the halide salt;

[0077] d) removing water of crystallization; and

[0078] e) Weigh the weight of the obtained anhydrous noble metal halide salt and calculate the content of the noble metal according to the following formula:

[0079]

[0080] Where Wt represents weight and M represents molar mass.

[0081] More preferably, in the embodiment described above, concentrated hydrochloric acid is used as concentrated hydrohalic acid. Furthermore, in step c), the chloride salt is preferably crystallized by evaporation.

[0082] Compared with the traditional analysis method, the method of the present invention has the following advantages and can be widely used for metal settlement, precision control and process control purposes:

[0083] -High analytical accuracy, for example, the absolute accuracy can reach 0.1%, which is consistent with the traditional gravimetric analysis method,

[0084] -The analysis process is simple, easy to operate, and the analysis cycle is short, such as only about 3 hours.

[0085] - Use fewer reagents, for example, in the case of nitrates, only the most common hydrochloric acid solution in the laboratory is used,

[0086] - Small equipment investment, for example, only heating equipment, dryer and analytical balance are required.

[0087] Specifically, the present invention relates to the following embodiments:

[0088] 1. A method for determining the precious metal content in a precious metal compound aqueous solution, wherein the precious metal compound is one of a precious metal halide salt, a precious metal nitrate, a precious metal carboxylate, an inorganic precious metal acid or an inorganic precious metal acid ammonium salt, the method comprising:

[0089] (i) If the noble metal compound is a noble metal halide salt, the noble metal halide salt in the noble metal halide salt aqueous solution is evaporated and crystallized to remove the crystal water, and then the weight of the obtained anhydrous noble metal halide salt is weighed to calculate the noble metal content according to the following formula:

[0090]

[0091] (ii) If the noble metal compound is a noble metal nitrate or a noble metal carboxylate, the noble metal nitrate or noble metal carboxylate in the noble metal nitrate or noble metal carboxylate aqueous solution is completely converted into a noble metal halide salt, the noble metal halide salt is evaporated and crystallized, the crystal water is removed, and then the weight of the obtained anhydrous noble metal halide salt is weighed, and the noble metal content is calculated according to the following formula:

[0092]

[0093] (iii) If the noble metal compound is an inorganic noble metal acid or an inorganic noble metal acid ammonium salt, the inorganic noble metal acid or inorganic noble metal acid ammonium salt aqueous solution is evaporated to dryness, and further heated until the inorganic noble metal acid or inorganic noble metal acid ammonium salt is completely decomposed into a single noble metal substance, and then the weight of the resulting single noble metal substance is weighed, and the noble metal content is calculated according to the following formula:

[0094]

[0095] Where Wt represents weight and M represents molar mass.

[0096] 2. A method as described in Embodiment 1, wherein the noble metal is a platinum group element, preferably one of Pt, Pd or Rh, more preferably Pd.

[0097] 3. The method according to embodiment 1 or 2, wherein the noble metal halide salt is one of chloride, bromide or iodide salts, more preferably one of chloride salts or bromide salts, more preferably one of chloride salts, such as one of platinum chloride, palladium chloride or rhodium chloride;

[0098] The noble metal nitrate is one of platinum nitrate, palladium nitrate or rhodium nitrate;

[0099] The noble metal carboxylate is selected from noble metal C1-C 20 One of the carboxylates, preferably selected from noble metal C2-C 10 One of the carboxylates, most preferably one of the noble metal acetates or noble metal octanoates;

[0100] The inorganic noble metal acid or inorganic noble metal acid ammonium salt is one of inorganic halogenated noble metal acids or inorganic halogenated noble metal acid ammonium salts, preferably one of inorganic chlorinated noble metal acids or inorganic chlorinated noble metal acid ammonium salts, or inorganic brominated noble metal acids or inorganic brominated noble metal acid ammonium salts; more preferably one of chloroplatinic acid or ammonium chloroplatinate, bromoplatinic acid or ammonium bromoplatinate, chloropalladic acid or ammonium chloropalladic acid, bromopalladic acid or ammonium bromopalladic acid, chlororhodic acid or ammonium chlororhodic acid, bromorhodic acid or ammonium bromorhodic acid; most preferably one of chloroplatinic acid or ammonium chloroplatinate, bromoplatinic acid or ammonium bromoplatinate.

[0101] 4. A method as described in any of embodiments 1-3, wherein the purity of the precious metal compound in the precious metal compound aqueous solution is greater than 99.95% by weight.

[0102] 5. The method according to any one of embodiments 1 to 4, wherein the crystallization is carried out at a temperature of 40 to 100°C, preferably 50 to 90°C, more preferably 60 to 80°C, for example 70°C.

[0103] 6. A method as described in any one of embodiments 1-5, wherein the step of completely converting the noble metal nitrate or noble metal carboxylate into a noble metal halide salt comprises adding a sufficient amount of concentrated hydrohalic acid to the solution, and then removing NO3 - Or carboxylate, thereby completely converting the noble metal nitrate or noble metal carboxylate into a noble metal halide salt.

[0104] 7. A method as described in embodiment 6, wherein the hydrohalic acid is selected from hydrochloric acid, hydrobromic acid or hydroiodic acid, preferably selected from hydrochloric acid or hydrobromic acid, and most preferably selected from hydrochloric acid.

[0105] 8. The method according to any one of embodiments 1 to 7, wherein the noble metal compound is a noble metal nitrate or a noble metal carboxylate, and the method comprises:

[0106] a) Add sufficient concentrated hydrohalic acid to the aqueous solution of noble metal nitrate or noble metal carboxylate, and then heat under boiling conditions to remove NO3 - or carboxylate, thereby completely converting the noble metal nitrate or noble metal carboxylate into a noble metal halide salt;

[0107] b) crystallizing the halide salt;

[0108] c) removing water of crystallization; and

[0109] d) Weigh the weight of the obtained anhydrous noble metal halide salt and calculate the content of the noble metal according to the following formula:

[0110]

[0111] Where Wt represents weight and M represents molar mass.

[0112] 9. A method for determining the precious metal content in a precious metal compound solid, wherein the precious metal compound is one of a precious metal halide salt, a precious metal nitrate, a precious metal carboxylate, an inorganic precious metal acid or an inorganic precious metal acid ammonium salt, the method comprising:

[0113] (i) If the noble metal compound is a noble metal halide salt, the possible crystal water or absorbed water is removed from the noble metal halide salt solid, and then the weight of the obtained anhydrous noble metal halide salt is weighed, and the content of the noble metal is calculated according to the following formula:

[0114]

[0115] (ii) If the noble metal compound is a noble metal nitrate or a noble metal carboxylate, the noble metal nitrate or noble metal carboxylate solid is dissolved in water to obtain a noble metal nitrate or noble metal carboxylate aqueous solution, the noble metal nitrate or noble metal carboxylate in the aqueous solution is converted into a noble metal halide salt and the noble metal halide salt is evaporated and crystallized; the crystal water is removed from the noble metal salt crystals, and then the weight of the obtained anhydrous noble metal halide salt is weighed, and the content of the noble metal is calculated according to the following formula:

[0116]

[0117] (iii) If the noble metal compound is an inorganic noble metal acid or an inorganic noble metal acid ammonium salt, the inorganic noble metal acid or inorganic noble metal acid ammonium salt solid is heated until it is completely decomposed into a single noble metal substance, and then the weight of the resulting single noble metal substance is weighed to calculate the noble metal content according to the following formula:

[0118]

[0119] Wherein Wt in each formula represents weight, and M represents molar mass.

[0120] 10. A method as described in Embodiment 9, wherein the noble metal is a platinum group element, preferably one of Pt, Pd or Rh, more preferably Pd.

[0121] 11. The method of embodiment 9 or 10, wherein:

[0122] The halide salt is one of chloride, bromide or iodide salts, more preferably one of chloride salts or bromide salts, most preferably one of chloride salts, such as one of platinum chloride, palladium chloride or rhodium chloride;

[0123] The noble metal nitrate is one of platinum nitrate, palladium nitrate or rhodium nitrate;

[0124] The noble metal carboxylate is selected from noble metal C1-C 20 One of the carboxylates, preferably selected from noble metal C2-C 10 One of the carboxylates, most preferably one of the noble metal acetates or noble metal octanoates;

[0125] The inorganic noble metal acid or inorganic noble metal acid ammonium salt is one of inorganic halogenated noble metal acids or inorganic halogenated noble metal acid ammonium salts, preferably one of inorganic chlorinated noble metal acids or inorganic chlorinated noble metal acid ammonium salts, or inorganic brominated noble metal acids or inorganic brominated noble metal acid ammonium salts; more preferably one of chloroplatinic acid or ammonium chloroplatinate, bromoplatinic acid or ammonium bromoplatinate, chloropalladic acid or ammonium chloropalladic acid, bromopalladic acid or ammonium bromopalladic acid, chlororhodic acid or ammonium chlororhodic acid, bromorhodic acid or ammonium bromorhodic acid; most preferably one of chloroplatinic acid or ammonium chloroplatinate, bromoplatinic acid or ammonium bromoplatinate.

[0126] 12. The method according to any one of embodiments 9 to 11, wherein the step of converting the noble metal nitrate or noble metal carboxylate into a halide salt comprises adding a sufficient amount of concentrated hydrohalic acid to the solution, and then removing NO3 - Or carboxylate, thereby completely converting the noble metal nitrate or noble metal carboxylate into a noble metal halide salt.

[0127] 13. A method as described in embodiment 12, wherein the hydrohalic acid is selected from one of hydrochloric acid, hydrobromic acid or hydroiodic acid, preferably selected from one of hydrochloric acid or hydrobromic acid, and most preferably selected from hydrochloric acid.

[0128] 14. The method of any one of embodiments 9-13, wherein the purity of the precious metal compound is greater than 99.95 wt%.

[0129] 15. The method of any one of embodiments 9-14, wherein the noble metal compound is a noble metal nitrate or a noble metal carboxylate, the method comprising:

[0130] a) dissolving a noble metal nitrate or noble metal carboxylate solid in water to obtain an aqueous solution; b) adding a sufficient amount of concentrated hydrohalic acid to the aqueous solution, and then heating under boiling conditions to remove NO3 - or carboxylate, thereby completely converting the noble metal nitrate or noble metal carboxylate into a noble metal halide salt;

[0131] c) crystallizing the halide salt;

[0132] d) removing water of crystallization; and

[0133] e) Weigh the weight of the obtained anhydrous noble metal halide salt and calculate the content of the noble metal according to the following formula:

[0134]

[0135] Where Wt represents weight and M represents molar mass.

[0136] Example

[0137] The present invention is illustrated using the following examples, which, however, are not to be construed as limiting the scope of the invention.

[0138] General Procedure

[0139] Procedure (I)—Determination of Pd content in Pd(NO3)2 aqueous solution

[0140] Weigh 1g of Pd(NO3)2 aqueous solution sample; add 10ml of concentrated hydrochloric acid to the Pd(NO3)2 solution and react at 100℃ for 1 hour to convert Pd(NO3)2 into PdCl2. Evaporate the obtained solution to dryness at 70℃ to obtain PdCl2·2H2O crystals. Heat the obtained crystals at 200℃ until the weight is constant to obtain anhydrous PdCl2. Cool the obtained anhydrous PdCl2 to room temperature in a desiccator, then weigh and calculate the Pd content in the Pd(NO3)2 solution according to the following formula:

[0141]

[0142] Procedure (II)—Determination of Pd content in aqueous PdCl2 solution

[0143] Weigh 1 g of a PdCl2 aqueous solution sample; evaporate the solution to dryness at 70°C to obtain PdCl2·2H2O crystals. Heat the obtained crystals at 200°C until the weight is constant. Obtain anhydrous PdCl2. Cool the obtained anhydrous PdCl2 to room temperature in a desiccator, then weigh and calculate the Pd content in the PdCl2 solution according to the following formula:

[0144]

[0145] The Pd content of various samples was determined according to the general procedure described above, with the results shown in Tables 1 and 2 below.

[0146] In addition, for comparison, the Pd content of the samples was determined using the traditional weighing method and the ICP-OES method, and the results are also summarized in Tables 1 and 2 below.

[0147] For the traditional weighing method, the procedure is as follows: weigh 1 g of PdCl2 aqueous solution sample; add 0.75 g of dibutyl ketone oxime to the solution and stir for 5 minutes, let stand at room temperature for 2 hours to obtain a suspended complex; filter, and then ash the filtrate at 700°C; reduce the ash product at 800°C for 0.5 hour under a H2 flow at a flow rate of 0.5 L / min; weigh the reduced product; calculate the Pd content.

[0148] Table 1 Example 1

[0149]

[0150]

[0151] Table 2 Example 2

[0152]

[0153] As can be seen from Tables 1 and 2 above, the method of the present invention has the advantages of high analytical accuracy, reproducibility comparable to that of the traditional weighing method, short analysis cycle (about 3 hours), less reagents used (in the case of nitrate, only the most common hydrochloric acid solution in the laboratory is used), less equipment investment (only heating equipment, dryer and analytical balance are required), etc., and can be widely used for metal settlement, precise control and process control and other purposes.

Claims

1. A method for determining the precious metal content in a precious metal compound aqueous solution, wherein the precious metal compound is one of a precious metal halide salt, a precious metal nitrate, a precious metal carboxylate or an inorganic precious metal acid, the method comprising: (i) If the noble metal compound is a noble metal halide salt, the noble metal halide salt in the noble metal halide salt aqueous solution is evaporated and crystallized to remove the crystal water, and then the weight of the obtained anhydrous noble metal halide salt is weighed to calculate the noble metal content according to the following formula: (ii) If the noble metal compound is a noble metal nitrate or a noble metal carboxylate, the noble metal nitrate or noble metal carboxylate in the noble metal nitrate or noble metal carboxylate aqueous solution is completely converted into a noble metal halide salt, the noble metal halide salt is evaporated and crystallized, the crystal water is removed, and then the weight of the obtained anhydrous noble metal halide salt is weighed, and the noble metal content is calculated according to the following formula: (iii) If the noble metal compound is an inorganic noble metal acid, the inorganic noble metal acid aqueous solution is evaporated to dryness, and further heated until the inorganic noble metal acid is completely decomposed into a single noble metal substance, and then the weight of the resulting single noble metal substance is weighed to calculate the noble metal content according to the following formula: Where Wt represents weight and M represents molar mass.

2. The method of claim 1, wherein the noble metal is a platinum group element.

3. The method of claim 2, wherein the noble metal is one of Pt, Pd or Rh. The method of claim 2 , wherein the noble metal is Pd.

5. The method of claim 1, wherein the noble metal halide salt is one of a chloride, bromide or iodide salt; The noble metal nitrate is one of platinum nitrate, palladium nitrate or rhodium nitrate; The noble metal carboxylate is selected from noble metal C1-C 20 One of the carboxylates; The inorganic noble metal acid is one of the inorganic halogenated noble metal acids.

6. The method of claim 2, wherein the noble metal halide salt is one of a chloride, bromide or iodide salt; The noble metal nitrate is one of platinum nitrate, palladium nitrate or rhodium nitrate; The noble metal carboxylate is selected from noble metal C1-C 20 One of the carboxylates; The inorganic noble metal acid is one of the inorganic halogenated noble metal acids.

7. The method according to claim 5 or 6, wherein the noble metal halide salt is one of a chloride salt or a bromide salt.

8. The method of claim 5 or 6, wherein the noble metal halide salt is a chloride salt.

9. The method of claim 5 or 6, wherein the noble metal halide salt is one of platinum chloride, palladium chloride or rhodium chloride.

10. The method of claim 5 or 6, wherein the noble metal carboxylate is selected from noble metal C2-C 10 A type of carboxylate.

11. The method according to claim 5 or 6, wherein the noble metal carboxylate is selected from one of noble metal acetates or noble metal octanoates.

12. The method according to claim 5 or 6, wherein the inorganic noble metal acid is one of an inorganic chlorinated noble metal acid or an inorganic brominated noble metal acid.

13. The method of claim 5 or 6, wherein the inorganic noble metal acid is one of chloroplatinic acid, bromoplatinic acid, chloropalladic acid, bromopalladic acid, chlororhodic acid, and bromorhodic acid.

14. The method according to claim 5 or 6, wherein the inorganic noble metal acid is one of chloroplatinic acid and bromoplatinic acid.

15. The method of claim 1, wherein the purity of the noble metal compound in the aqueous solution of the noble metal compound is greater than 99.95% by weight.

16. The method of claim 2, wherein the purity of the noble metal compound in the noble metal compound aqueous solution is greater than 99.95% by weight.

17. The method of claim 5, wherein the purity of the noble metal compound in the aqueous solution of the noble metal compound is greater than 99.95% by weight.

18. The method of claim 6, wherein the purity of the noble metal compound in the noble metal compound aqueous solution is greater than 99.95% by weight.

19. The process of any one of claims 1-6 and 15-18, wherein the crystallization is at 40°C to 100°C.

20. The process of claim 19, wherein the crystallization is carried out at a temperature of 50 to 90°C.

21. The process of claim 19, wherein the crystallization is carried out at a temperature of 60 to 80°C.

22. The process of claim 19, wherein the crystallization is carried out at a temperature of 70°C.

23. The method of any one of claims 1 to 6 and 15 to 18, wherein the step of completely converting the noble metal nitrate or noble metal carboxylate into a noble metal halide salt comprises adding a sufficient amount of concentrated hydrohalic acid to the solution, and then removing NO3 - Or carboxylate, thereby completely converting the noble metal nitrate or noble metal carboxylate into a noble metal halide salt.

24. The method of claim 19, wherein the step of completely converting the noble metal nitrate or noble metal carboxylate into the noble metal halide salt comprises adding a sufficient amount of concentrated hydrohalic acid to the solution, and then removing NO3 - Or carboxylate, thereby completely converting the noble metal nitrate or noble metal carboxylate into a noble metal halide salt.

25. The method of claim 23, wherein the hydrohalic acid is selected from hydrochloric acid, hydrobromic acid or hydroiodic acid.

26. The method of claim 24, wherein the hydrohalic acid is selected from hydrochloric acid, hydrobromic acid or hydroiodic acid.

27. The method of claim 25, wherein the hydrohalic acid is selected from hydrochloric acid or hydrobromic acid.

28. The method of claim 25, wherein the hydrohalic acid is selected from hydrochloric acid.

29. The method according to any one of claims 1 to 6 and 15 to 18, wherein the noble metal compound is a noble metal nitrate or a noble metal carboxylate, and the method comprises: a) Add sufficient concentrated hydrohalic acid to the aqueous solution of noble metal nitrate or noble metal carboxylate, and then heat under boiling conditions to remove NO3 - or carboxylate, thereby completely converting the noble metal nitrate or noble metal carboxylate into a noble metal halide salt; b) crystallizing the halide salt; c) removing water of crystallization; and d) Weigh the weight of the obtained anhydrous noble metal halide salt and calculate the content of the noble metal according to the following formula: Where Wt represents weight and M represents molar mass.

30. The method according to claim 26, wherein the noble metal compound is a noble metal nitrate or a noble metal carboxylate, and the method comprises: a) Add sufficient concentrated hydrohalic acid to the aqueous solution of noble metal nitrate or noble metal carboxylate, and then heat under boiling conditions to remove NO3 - or carboxylate, thereby completely converting the noble metal nitrate or noble metal carboxylate into a noble metal halide salt; b) crystallizing the halide salt; c) removing water of crystallization; and d) Weigh the weight of the obtained anhydrous noble metal halide salt and calculate the content of the noble metal according to the following formula: Where Wt represents weight and M represents molar mass.

31. A method for determining the precious metal content in a precious metal compound solid, wherein the precious metal compound is one of a precious metal halide salt, a precious metal nitrate, a precious metal carboxylate or an inorganic precious metal acid, the method comprising: (i) If the noble metal compound is a noble metal halide salt, the possible crystal water or absorbed water is removed from the noble metal halide salt solid, and then the weight of the obtained anhydrous noble metal halide salt is weighed, and the content of the noble metal is calculated according to the following formula: (ii) If the noble metal compound is a noble metal nitrate or a noble metal carboxylate, the noble metal nitrate or noble metal carboxylate solid is dissolved in water to obtain a noble metal nitrate or noble metal carboxylate aqueous solution, the noble metal nitrate or noble metal carboxylate in the aqueous solution is converted into a noble metal halide salt and the noble metal halide salt is evaporated and crystallized; the crystal water is removed from the noble metal salt crystals, and then the weight of the obtained anhydrous noble metal halide salt is weighed, and the content of the noble metal is calculated according to the following formula: (iii) If the noble metal compound is an inorganic noble metal acid, the inorganic noble metal acid solid is heated until it is completely decomposed into a noble metal element, and then the weight of the obtained noble metal element is weighed to calculate the noble metal content according to the following formula: Wherein Wt in each formula represents weight, and M represents molar mass.

32. The method of claim 31, wherein the noble metal is a platinum group element.

33. The method of claim 32, wherein the noble metal is one of Pt, Pd or Rh.

34. The method of claim 32, wherein the noble metal is Pd.

35. The method of claim 31, wherein: The halide salt is one of chloride, bromide or iodide salt; The noble metal nitrate is one of platinum nitrate, palladium nitrate or rhodium nitrate; The noble metal carboxylate is selected from noble metal C1-C 20 One of the carboxylates; The inorganic noble metal acid is one of the inorganic halogenated noble metal acids.

36. The method of claim 32, wherein: The halide salt is one of chloride, bromide or iodide salt; The noble metal nitrate is one of platinum nitrate, palladium nitrate or rhodium nitrate; The noble metal carboxylate is selected from noble metal C1-C 20 One of the carboxylates; The inorganic noble metal acid is one of the inorganic halogenated noble metal acids.

37. The method of claim 35 or 36, wherein the halide salt is one of a chloride salt or a bromide salt.

38. The method of claim 35 or 36, wherein the halide salt is a chloride salt.

39. The method of claim 35 or 36, wherein the halide salt is one of platinum chloride, palladium chloride or rhodium chloride.

40. The method of claim 35 or 36, wherein the noble metal carboxylate is selected from noble metal C2-C 10 A type of carboxylate.

41. The method of claim 35 or 36, wherein the noble metal carboxylate is selected from one of a noble metal acetate or a noble metal octanoate.

42. The method of claim 35 or 36, wherein the inorganic noble metal acid is one of an inorganic chlorinated noble metal acid or an inorganic brominated noble metal acid.

43. The method of claim 35 or 36, wherein the inorganic noble metal acid is one of chloroplatinic acid, bromoplatinic acid, chloropalladic acid, bromopalladic acid, chlororhodic acid, and bromorhodic acid.

44. The method of claim 35 or 36, wherein the inorganic noble metal acid is one of chloroplatinic acid and bromoplatinic acid.

45. The method of claim 31, wherein the step of converting the noble metal nitrate or noble metal carboxylate into a halide salt comprises adding a sufficient amount of concentrated hydrohalic acid to the solution and then removing NO3 - Or carboxylate, thereby completely converting the noble metal nitrate or noble metal carboxylate into a noble metal halide salt.

46. ​​The method of claim 32, wherein the step of converting the noble metal nitrate or noble metal carboxylate into a halide salt comprises adding a sufficient amount of concentrated hydrohalic acid to the solution and then removing NO3 - Or carboxylate, thereby completely converting the noble metal nitrate or noble metal carboxylate into a noble metal halide salt.

47. The method of claim 35, wherein the step of converting the noble metal nitrate or noble metal carboxylate into a halide salt comprises adding a sufficient amount of concentrated hydrohalic acid to the solution and then removing NO3 - Or carboxylate, thereby completely converting the noble metal nitrate or noble metal carboxylate into a noble metal halide salt.

48. The method of claim 36, wherein the step of converting the noble metal nitrate or noble metal carboxylate into a halide salt comprises adding a sufficient amount of concentrated hydrohalic acid to the solution and then removing NO3 - Or carboxylate, thereby completely converting the noble metal nitrate or noble metal carboxylate into a noble metal halide salt.

49. The method of any one of claims 45-48, wherein the hydrohalic acid is selected from one of hydrochloric acid, hydrobromic acid or hydroiodic acid.

50. The method of claim 49, wherein the hydrohalic acid is selected from one of hydrochloric acid or hydrobromic acid.

51. The method of claim 49, wherein the hydrohalic acid is selected from hydrochloric acid.

52. The method of any one of claims 31-36 and 45-48, wherein the purity of the precious metal compound is greater than 99.95% by weight.

53. The method of claim 49, wherein the noble metal compound has a purity greater than 99.95% by weight.

54. The method of any one of claims 31-36 and 45-48, wherein the noble metal compound is a noble metal nitrate or a noble metal carboxylate, the method comprising: a) dissolving a noble metal nitrate or noble metal carboxylate solid in water to obtain an aqueous solution; b) adding a sufficient amount of concentrated hydrohalic acid to the aqueous solution, and then heating under boiling conditions to remove NO3 - or carboxylate, thereby completely converting the noble metal nitrate or noble metal carboxylate into a noble metal halide salt; c) crystallizing the halide salt; d) removing water of crystallization; and e) Weigh the weight of the obtained anhydrous noble metal halide salt and calculate the content of the noble metal according to the following formula: Where Wt represents weight and M represents molar mass.

55. The method of claim 53, wherein the noble metal compound is a noble metal nitrate or a noble metal carboxylate, the method comprising: a) dissolving a noble metal nitrate or noble metal carboxylate solid in water to obtain an aqueous solution; b) adding a sufficient amount of concentrated hydrohalic acid to the aqueous solution, and then heating under boiling conditions to remove NO3 - or carboxylate, thereby completely converting the noble metal nitrate or noble metal carboxylate into a noble metal halide salt; c) crystallizing the halide salt; d) removing water of crystallization; and e) Weigh the weight of the obtained anhydrous noble metal halide salt and calculate the content of the noble metal according to the following formula: Where Wt represents weight and M represents molar mass.

Images