Method for analyzing content of noble metal in catalyst

Abstract

The invention relates to the field of precious metal analysis, and discloses a method for analyzing the content of precious metal in a catalyst. The invention relates to a method for analyzing the content of noble metals in a catalyst, which comprises the following steps: (1) carrying out aerobic firing on the catalyst at 450-650 DEG C to obtain a firing product; (2) grinding the firing product, so that the average particle size of the firing product is not greater than 120 microns; (3) dissolving the calcined product ground in the step (2) in an acid for digestion, and then determining the content of the noble metal, the acid being any one of inorganic acids; wherein the catalyst comprises a carrier and a noble metal, the carrier is alumina, and the noble metal is platinum and / or palladium. The method has the advantages of being high in accuracy, simple and rapid in analysis operation process and friendly to environment and measuring equipment.

Description

Technical Field

[0001] The invention relates to the field of precious metal analysis, and in particular to a method for analyzing the precious metal content in a catalyst. Background Art

[0002] The reforming oil liquid phase hydrodeolefination process now often uses precious metal (platinum, palladium) catalysts, which have low reaction severity, reaction temperature of 120℃~170℃, reaction pressure of 1.0MPa~2.4MPa, aromatic loss rate of less than 0.2%, and the catalyst can operate stably for a long period of time. The deactivated catalyst is regenerated off-site, and the platinum, palladium and other precious metals in the discarded catalyst can be recycled. Therefore, it is necessary to establish a set of analytical methods for quickly and accurately determining the content of precious metals such as platinum and palladium in the catalyst to cooperate with the research and development, production and recovery of the catalyst.

[0003] In the prior art, different pretreatment methods are required to cooperate with the analysis of precious metal catalysts according to the type of catalyst and the mass fraction of precious metals contained. Common catalyst pretreatment methods include mixed acid decomposition method, pressurized digestion method and alkali fusion method. Inductively coupled plasma emission spectrometry often uses mixed acid decomposition method (mixture of hydrochloric acid, nitric acid, hydrofluoric acid, perchloric acid, etc. in different proportions) for the analysis of platinum and palladium in catalysts, and often requires the addition of H 2 O 2 The presence of substances such as alkali and alkali chloride makes the analytical operation process more complicated, causes varying degrees of corrosion to the instrument and is not environmentally friendly; the alkali fusion method uses excessive alkali, and the excess alkali itself as impurities and the impurities corroded from the crucible will seriously interfere with the stability of the measurement data. Summary of the invention

[0004] The purpose of the present invention is to overcome the problems existing in the existing analytical methods for determining the content of platinum and palladium noble metals in catalysts, such as complex analytical process and the need for further improvement of accuracy, and to provide an analytical method for the content of noble metals in catalysts. The method has the advantages of high accuracy, simple and fast analytical operation process, and is friendly to the environment and measuring equipment.

[0005] In order to achieve the above object, the present invention provides a method for analyzing the content of precious metals in a catalyst, the method comprising the following steps:

[0006] (1) burning the catalyst in the presence of oxygen at 450-650° C. to obtain a burning product;

[0007] (2) grinding the calcined product so that the average particle size of the calcined product is no greater than 120 μm;

[0008] (3) dissolving the calcined product after grinding in step (2) in an acid for digestion, and then determining the content of the precious metal, wherein the acid is any one of inorganic acids;

[0009] Wherein, the catalyst comprises a carrier and a noble metal, the carrier is alumina, and the noble metal is platinum and / or palladium.

[0010] Preferably, based on the total mass of the catalyst, the mass content of the precious metal is not higher than 0.5%.

[0011] Through the above technical solution, the beneficial effects of the present invention include:

[0012] The method of the present invention pre-treats a specific type of catalyst by adopting a process of aerobic burning-grinding-single inorganic acid digestion at a specific temperature, which is beneficial to improving the dissolution rate of the catalyst and thus improving the accuracy of subsequent measurements.

[0013] The method of the present invention does not add other reagents (such as oxidants, etc.) except a single inorganic acid, thereby avoiding interference of other added reagents on subsequent determinations, improving the stability of the determination, and the operation process is simple and fast, and has the advantages of being friendly to the environment and the determination equipment and having less pollution. DETAILED DESCRIPTION

[0014] The endpoints and any values ​​of the ranges disclosed in this article are not limited to the precise ranges or values, and these ranges or values ​​should be understood to include values ​​close to these ranges or values. For numerical ranges, the endpoint values ​​of each range, the endpoint values ​​of each range and the individual point values, and the individual point values ​​can be combined with each other to obtain one or more new numerical ranges, which should be considered as specifically disclosed in this article.

[0015] In one aspect, the present invention provides a method for analyzing the content of precious metals in a catalyst, the method comprising the following steps:

[0016] (1) burning the catalyst in the presence of oxygen at 450-650° C. to obtain a burning product;

[0017] (2) grinding the calcined product so that the average particle size of the calcined product is no greater than 120 μm;

[0018] (3) dissolving the calcined product after grinding in step (2) in an acid for digestion, and then determining the content of the precious metal, wherein the acid is any one of inorganic acids;

[0019] Wherein, the catalyst comprises a carrier and a noble metal, the carrier is alumina, and the noble metal is platinum and / or palladium.

[0020] In the prior art, the commonly used catalyst for liquid-phase hydrodeolefination of reforming oil includes a carrier and an active component. The commonly used carrier may be inorganic oxides such as alumina, zirconium oxide, magnesium oxide, silicon oxide, or other carriers such as molecular sieves. The active component may include precious metal components such as platinum and / or palladium, and may also include non-precious metal components such as zirconium. For the determination of the precious metal content in a catalyst whose carrier is alumina and contains platinum and / or palladium precious metal active components, the method provided by the present invention pre-treats a specific type of catalyst by adopting a process of aerobic calcination-grinding-single inorganic acid digestion at a specific temperature, which is beneficial to improve the dissolution rate of the catalyst, thereby improving the accuracy of subsequent determination.

[0021] In the present invention, "the acid is any one of inorganic acids" means that a single inorganic acid is used.

[0022] The alumina carrier of the present invention is a conventional choice in the art. Preferably, the alumina is γ-Al 2 O 3 and / or θ-Al 2 O 3 .

[0023] The method of the present invention is suitable for the determination of different concentrations of precious metals, and is particularly suitable for the determination of low-concentration precious metal content. Preferably, based on the total mass of the catalyst, the mass content of the precious metal is not higher than 0.5%, for example, the mass content of the precious metal can be 0.005%, 0.01%, 0.05%, 0.1%, 0.15%, 0.2%, 0.25%, 0.3%, 0.35%, 0.4%, 0.45%, 0.5%, and any value in the range formed by any two of these values.

[0024] According to the present invention, preferably, based on the total mass of the catalyst, the mass content of the carrier is not less than 97%.

[0025] The method of the present invention is particularly suitable for the catalyst having the above composition, and the determination accuracy of the precious metal content is high.

[0026] According to the present invention, preferably, the catalyst contains zirconium and silicon, and the mass content of zirconium is not higher than 0.1% and the mass content of silicon is not higher than 0.1% based on the total mass of the catalyst. When the content of zirconium and silicon is within the above range, there is basically no interference with the determination result, and the accuracy of the analysis method is high.

[0027] The catalyst of the present invention may also contain impurities such as sodium and calcium, but since their contents are extremely low, they have no effect on the measurement results and can be ignored.

[0028] The analytical method provided by the present invention is suitable for catalysts with the above composition obtained by various existing methods. The catalyst can be new and intact, or it can be waste, and the present invention has no limitation on this.

[0029] In the present invention, the calcination temperature in step (1) is 450-650°C, preferably 500-600°C, such as 450°C, 460°C, 470°C, 480°C, 490°C, 500°C, 510°C, 520°C, 530°C, 540°C, 550°C, 560°C, 570°C, 580°C, 590°C, 600°C, 610°C, 620°C, 630°C, 640°C, 650°C, and any value in the range formed by any two of these values. This preferred embodiment is beneficial to improving the solubility of the subsequent catalyst.

[0030] It should be noted that if the calcination temperature in step (1) is too low (e.g., 100-350°C) or too high (e.g., 1000-1500°C), the solubility of the subsequent catalyst will be greatly reduced. The reasons are speculated to be: if the calcination temperature in step (1) is too low, the oxidation state of the precious metal Pt in the catalyst will not be completely transformed, resulting in a low measurement result; and if the calcination temperature in step (1) is too high, the crystal form of alumina will change and it will not be dissolved, which will affect the determination of the precious metal.

[0031] According to the present invention, preferably, the burning time in step (1) is 4-12 hours, preferably 4-6 hours, such as 4 hours, 5 hours, 6 hours, 7 hours, 8 hours, 9 hours, 10 hours, 11 hours, 12 hours, and any value in the range formed by any two of these values. This preferred embodiment is further conducive to improving the solubility of the catalyst.

[0032] In the present invention, the aerobic combustion refers to combustion in an oxygen-containing atmosphere.

[0033] Preferably, the burning in step (1) is carried out in an air atmosphere, which may include a flowing atmosphere or a static atmosphere.

[0034] According to a specific embodiment of the present invention, the calcined product is placed in a dryer to cool to room temperature and then ground.

[0035] The inventors of the present invention have found in the course of research that grinding the calcination product to a certain degree before digestion can completely dissolve the catalyst. Preferably, in step (2), the calcination product is ground so that the average particle size of the calcination product is 100-120 μm, for example, 100 μm, 105 μm, 110 μm, 115 μm, 120 μm, and any value in the range formed by any two of these values.

[0036] The present invention has no particular limitation on the specific operation of the grinding, and it can be carried out by conventional methods in the art, as long as the average particle size of the calcined product meets the above range.

[0037] The present invention has a wide range of acid types, preferably, the acid is hydrochloric acid or nitric acid, preferably hydrochloric acid. This preferred embodiment is conducive to the complete dissolution of the catalyst and is more convenient for experimenters to use.

[0038] The present invention has no particular limitation on the concentration of the acid in step (3), which can be selected conventionally in the art. Preferably, the concentration of the acid is 35-68 wt%.

[0039] Preferably, the concentration of the hydrochloric acid is 35-38 wt %.

[0040] Preferably, the concentration of the nitric acid is 65-68 wt %.

[0041] Preferably, in step (3), the volume of the acid used is 10-50 mL, preferably 12.5-25 mL, relative to 1 g of the catalyst. This preferred embodiment is conducive to ensuring complete dissolution of the catalyst while requiring less inorganic acid.

[0042] According to the present invention, preferably, the digestion conditions in step (3) include: a temperature of 160-200°C, preferably 175-185°C, such as 160°C, 165°C, 170°C, 175°C, 180°C, 185°C, 190°C, 195°C, 200°C, and any value in the range formed by any two of these values; a time of 1-12h, preferably 5-6h, such as 1h, 2h, 3h, 4h, 5h, 6h, 7h, 8h, 9h, 10h, 11h, 12h, and any value in the range formed by any two of these values. This preferred embodiment allows the catalyst to be completely dissolved.

[0043] The present invention has no particular limitation on the digestion equipment used to achieve the above digestion, and can be any commonly used digestion equipment in the art. For example, a microwave digestion instrument, a pressure dissolution bomb, etc. can be used. The present invention preferably uses a pressure dissolution bomb.

[0044] Preferably, the method further comprises: adjusting the volume of the digested material. The present invention has no particular limitation on the conditions for adjusting the volume, for example, adjusting the volume of the digested material to 25-200 mL with water at room temperature.

[0045] According to the present invention, preferably, the content of precious metals is determined by inductively coupled plasma emission spectrometry. This preferred embodiment has high sensitivity, high accuracy and fast detection.

[0046] According to the present invention, preferably, the method does not include the addition of an oxidant. The oxidant of the present invention is a conventional choice in the art, such as peroxide, perchloric acid, etc.

[0047] The method of the present invention does not add other reagents except a single inorganic acid, thus avoiding interference of other added reagents on subsequent determination, improving the stability of determination, and the operation process is simple and fast, friendly to the environment and determination equipment, and less polluting.

[0048] According to a particularly preferred embodiment of the present invention, a method for analyzing the precious metal content in a catalyst comprises the following steps:

[0049] (1) burning the catalyst in the presence of oxygen at 500-600° C. to obtain a burning product;

[0050] (2) grinding the calcined product so that the average particle size of the calcined product is 100-120 μm;

[0051] (3) dissolving the calcined product after grinding in step (2) in hydrochloric acid or nitric acid for digestion, and then determining the content of the precious metal;

[0052] Wherein, the catalyst comprises a carrier and a noble metal, the carrier is alumina, and the noble metal is platinum and / or palladium;

[0053] Wherein, based on the total mass of the catalyst, the mass content of the precious metal is not higher than 0.5%;

[0054] Wherein, the digestion conditions in step (3) include: temperature of 175-185° C. and time of 5-6 h.

[0055] The above preferred implementation is more conducive to complete dissolution of the catalyst and improves the accuracy of subsequent measurements.

[0056] The present invention will be described in detail below through examples.

[0057] In the following examples, the content of precious metals in catalysts of known composition is analyzed to demonstrate the accuracy of the analysis method of the present invention, wherein the content of each component in the catalyst of known composition is calculated by the feed amount; the content of precious metals in the catalyst is measured by inductively coupled plasma optical emission spectrometry (ICP-OES).

[0058] Example 1

[0059] The reformed oil deolefination catalyst (γ-alumina content of 99wt%, Pt content of 0.093wt%, Pd content of 0.197wt%, and the remaining content is other impurities that do not affect the measurement results) is placed in a high-temperature muffle furnace and burned in air at 550°C for 6h to obtain a burning product. The burning product is taken out and placed in a dryer to cool to room temperature, and then ground with agate to an average particle size of 120μm. 0.2218g of the ground burning product is placed in a pressure bomb, 3mL of hydrochloric acid (37wt%) is added, and then the pressure bomb containing the burning product is placed in an oven at 180°C for 6h to obtain the digested material. The digested material is cooled to room temperature, then transferred to a 50mL volumetric flask and diluted with water to obtain a solution containing precious metals. The precious metal content in the solution was determined by ICP-OES, and the results are shown in Table 1.

[0060] Example 2

[0061] The continuous reforming catalyst (γ-alumina content is 99wt%, Pt content is 0.28wt%, and the remaining content is other impurities that do not affect the measurement results) is placed in a high-temperature muffle furnace and burned in air at 575°C for 5h to obtain a burning product. The burning product is taken out and placed in a dryer to cool to room temperature, and then ground evenly with agate to an average particle size of 100μm. 0.2205g of the ground burning product is placed in a pressure bomb, 3.5mL of hydrochloric acid (37wt%) is added, and then the pressure bomb containing the burning product is placed in an oven at 178°C for 5.5h to obtain the digested material. The digested material is cooled to room temperature, then transferred to a 50mL volumetric flask and diluted with water to obtain a solution containing precious metals. The precious metal content in the solution was determined by ICP-OES, and the results are shown in Table 1.

[0062] Example 3

[0063] The reformed oil deolefination catalyst (γ-alumina content of 99wt%, Pt content of 0.093wt%, Pd content of 0.197wt%, and the remaining content is other impurities that do not affect the measurement results) is placed in a high-temperature muffle furnace and burned in air at 580°C for 5.5h to obtain a burning product. The burning product is taken out and placed in a dryer to cool to room temperature, and then ground evenly with agate to an average particle size of 120μm. 0.2218g of the ground burning product is placed in a microwave digestion tank, 4.5mL of hydrochloric acid (37wt%) is added, and then the microwave digestion tank containing the burning product is placed in a microwave digestion instrument at 180°C for 60min to obtain the digested material. The digested material is cooled to room temperature, then transferred to a 50mL volumetric flask and diluted with water to obtain a solution containing precious metals. The precious metal content in the solution is determined by ICP-OES, and the results are shown in Table 1.

[0064] Comparative Example 1

[0065] The method of Example 1 was followed, except that the catalyst was not calcined but directly ground, and other conditions remained the same. The noble metal content in the solution was determined by ICP-OES, and the results are shown in Table 1.

[0066] Comparative Example 2

[0067] The method of Example 1 was followed, except that the calcined product was not ground, but directly digested by adding 3 mL of hydrochloric acid. At this time, the particle size of the calcined product was 1.4 mm to 2 mm. The precious metal content in the solution was determined by ICP-OES, and the results are shown in Table 1.

[0068] Comparative Example 3

[0069] The method of Example 1 was followed, except that the calcined product was ground to an average particle size of about 500 μm. The noble metal content in the solution was determined by ICP-OES, and the results are shown in Table 1.

[0070] Comparative Example 4

[0071] The method of Example 1 was followed, except that the calcination conditions were changed to: calcination at 250° C. in air for 6 h to obtain a calcination product. The content of precious metals in the solution was determined by ICP-OES, and the results are shown in Table 1.

[0072] Comparative Example 5

[0073] Analytical methods of the prior art

[0074] 0.4000g of platinum-palladium alumina catalyst (alumina content of 99wt%, Pt content of 0.08wt%, Pd content of 0.19wt%) was taken and placed in a microwave digestion tank, 8mL of concentrated nitric acid and 2mL of hydrofluoric acid (superior grade) were added, and then the microwave digestion tank containing the catalyst was placed in a microwave digestion instrument and digested at 200°C for 35min to obtain the digested material. After the digestion is complete, 2mL of perchloric acid (oxidant) was added to the digestion tank and placed in an acid remover for acid removal. The acid-removed material was cooled to room temperature, and then transferred to a 50mL volumetric flask and diluted with water to obtain a solution containing precious metals. The precious metal content in the solution was determined by ICP-OES, and the results are shown in Table 1.

[0075] Table 1

[0076]

[0077] Note: A clear solution means that the catalyst is completely dissolved;

[0078] The presence of black insoluble matter in the solution indicates that the catalyst is not completely dissolved.

[0079] It can be seen from the results in Table 1 that, compared with Comparative Examples 1-4, the analysis method provided by the present invention has better dissolution effect of platinum and / or palladium noble metals and higher accuracy.

[0080] Compared with Comparative Example 5, under the condition of comparable accuracy, the method of the present invention does not add any reagents (such as oxidants, etc.) other than a single inorganic acid, and the operation process is simple and fast, friendly to the environment and measurement equipment, and has less pollution.

[0081] The preferred embodiments of the present invention are described in detail above, but the present invention is not limited thereto. Within the technical concept of the present invention, the technical solution of the present invention can be subjected to a variety of simple modifications, including the combination of various technical features in any other suitable manner, and these simple modifications and combinations should also be regarded as the contents disclosed by the present invention and belong to the protection scope of the present invention.

Claims

1. A method for analyzing the content of precious metals in a catalyst, characterized in that: The method comprises the following steps: (1) burning the catalyst in the presence of oxygen at 450-650° C. to obtain a burning product; (2) grinding the calcined product so that the average particle size of the calcined product is no greater than 120 μm; (3) dissolving the calcined product after grinding in step (2) in an acid for digestion, and then determining the content of the precious metal, wherein the acid is any one of inorganic acids; Wherein, the catalyst comprises a carrier and a noble metal, the carrier is alumina, and the noble metal is platinum and / or palladium.

2. The method according to claim 1, wherein: Based on the total mass of the catalyst, the mass content of the precious metal is not higher than 0.5%; Preferably, based on the total mass of the catalyst, the mass content of the carrier is not less than 97%.

3. The method according to claim 1, wherein: The catalyst contains an optional Zr element and an optional Si element. Based on the total mass of the catalyst, the mass content of the Zr element is not higher than 0.1%, and the mass content of the Si element is not higher than 0.1%.

4. The method according to any one of claims 1 to 3, wherein: The calcination temperature in step (1) is 500-600° C. Preferably, the burning time in step (1) is 4-12 hours, preferably 4-6 hours.

5. The method according to any one of claims 1 to 4, wherein: In step (2), the calcination product is ground so that the average particle size of the calcination product is 100-120 μm.

6. The method according to any one of claims 1 to 5, wherein: In step (3), the volume amount of the acid used is 10-50 mL, preferably 12.5-25 mL, relative to 1 g of the catalyst.

7. The method according to any one of claims 1 to 6, wherein: The acid is hydrochloric acid or nitric acid, preferably hydrochloric acid; Preferably, the concentration of the acid is 35-68wt%; Preferably, the concentration of the hydrochloric acid is 35-38wt%; Preferably, the concentration of the nitric acid is 65-68 wt %.

8. The method according to any one of claims 1 to 7, wherein: The digestion conditions in step (3) include: temperature of 160-200° C., preferably 175-185° C.; time of 1-12 h, preferably 5-6 h.

9. The method according to any one of claims 1 to 8, wherein: Inductively coupled plasma optical emission spectrometry was used to determine the content of precious metals.

10. The method according to any one of claims 1 to 9, wherein: The method does not involve the addition of an oxidizing agent.

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