Method for measuring contents of calcium and copper in catalyst auxiliary agent

Abstract

The invention discloses a method for measuring the content of calcium and copper in a catalyst promoter, which comprises the following steps: step 1, weighing a catalyst promoter sample after grinding and sieving, adding mixed acid, heating and dissolving, cooling to room temperature, fixing the volume, and uniformly shaking for later use; step 2, respectively adding an aluminum matrix into the standard solutions of calcium and copper elements, and gradually diluting into standard working solutions with a series of concentrations; 3, adjusting the working parameters of the instrument; 4, drawing a standard curve; and 5, sample determination. According to the method, iodine and potassium iodide reagents with relatively high price are not needed, and calcium and copper can be simultaneously determined, so that resources are saved, the cost is reduced, and the analysis efficiency is improved.

Description

Technical Field

[0001] The present invention relates to the technical field of element determination in catalyst additives, in particular to a method for determining the contents of calcium and copper in catalyst additives. Background Art

[0002] Catalyst promoters are key materials in dehydrogenation reactions. Calcium and copper are important components in the promoter, and their content directly affects the performance and service life of the heat-generating promoter.

[0003] At present, commonly used methods for analyzing calcium and copper content include titration, atomic absorption spectrometry (AAS), spectrophotometry, inductively coupled plasma optical emission spectrometry (ICP-OES), etc. However, these public methods are not suitable for the determination of catalyst additives. For example, the iodine titration method used in the public method HG / T 5769-2021 Determination of copper in copper-based waste catalysts can only determine the copper content, while the determination of calcium content requires another method of analysis, resulting in low analysis efficiency and waste of reagents. For example, the public method YST1562.1-2022 Chemical Analysis Method of Tungsten-Copper Alloy Part 1: Determination of Copper Content, iodine titration and inductively coupled plasma atomic emission spectrometry, only provides a method for determining copper content by inductively coupled plasma atomic emission spectrometry, and does not take into account the interference of other elements and the interference shielding of the matrix, resulting in inaccurate determination of the calcium and copper content of the heating additive.

[0004] Therefore, how to establish an accurate, rapid and simple method for determining calcium and copper content is of great significance for the optimization of propane dehydrogenation process and the control of exothermic additive production process. Summary of the Invention

[0005] The present invention aims to solve the problem that there is no public report on the analytical method for the calcium and copper contents in the catalyst additive, and provides a method for determining the calcium and copper contents in the catalyst additive.

[0006] In order to achieve the above technical objectives, the technical solution provided by the present invention is:

[0007] A method for determining the calcium and copper contents in a catalyst promoter comprises the following steps:

[0008] Step 1: Weigh the catalyst additive sample, add the mixed acid, heat and dissolve, cool to room temperature, dilute to volume, shake well and set aside;

[0009] Step 2: Add aluminum matrix to the standard solutions of calcium and copper elements respectively, and dilute them step by step to form a series of standard working solutions;

[0010] Step 3: Adjust instrument operating parameters;

[0011] Step 4: draw the standard curve;

[0012] Step 5: Sample measurement.

[0013] Furthermore, in step 1, the mixed acid is a combination of two or three of phosphoric acid, sulfuric acid, hydrochloric acid, and nitric acid.

[0014] In a specific embodiment, the catalyst additive sample is a propane dehydrogenation exothermic additive, and the phosphoric acid concentration is 85%, the sulfuric acid concentration is 98%, the hydrochloric acid concentration is 37%, and the nitric acid concentration is 65%.

[0015] Furthermore, the volume of the phosphoric acid is 0-10 ml, the volume of the sulfuric acid is 0-10 ml, the volume of the nitric acid is 0-5 ml, the volume of the hydrochloric acid is 0-10 ml, and the total amount of the mixed acid is 10 ml-12 ml.

[0016] Furthermore, preferably, the volume of phosphoric acid is 5 ml and the volume of sulfuric acid is 5 ml.

[0017] Furthermore, in step 1, the catalyst adjuvant sample needs to be ground and sieved, and the sieve used for sieving has a mesh size of 200-220.

[0018] Furthermore, in step 1, the sample amount is 100 mg-150 mg, the heating temperature is 350-400° C., and the heating time is 30 min.

[0019] The mass of the sample includes, but is not limited to, 100.0 mg, 110.0 mg, 120.0 mg, 130.0 mg, 140.0 mg, or 150.0 mg, and may also be any value between 100.0 mg and 150.0 mg. The sample should be weighed to the nearest 0.1 mg.

[0020] In step 2, when preparing the diluted concentrations of calcium and copper element standard solutions, the amount of matrix aluminum added is based on the aluminum content in the sample. By mass ratio, the matrix aluminum in the diluted concentrations of calcium and copper element standard solutions: aluminum in the sample is 1:0.9-1.1.

[0021] In a specific embodiment, the concentration of the calcium and copper element standard stock solutions is 100 μg / ml. 0 ml to 20 ml of the calcium and copper element standard stock solutions are respectively transferred and 4 ml of the aluminum matrix is ​​added to make the volume to 100 ml. The diluted concentrations of calcium and copper elements are 0 μg / ml to 20 μg / ml, respectively.

[0022] Specifically, the dilution concentrations of calcium and copper elements are 0 μg / ml, 5 μg / ml, 10 μg / ml, 15 μg / ml, and 20 μg / ml, respectively; when digesting the sample, generally 0.1-0.15 g of aluminum 0.039 g-0.0585 g is weighed, and the aluminum matrix is ​​aluminum chloride hexahydrate (M: 241.43). 5.5-8.2 g of aluminum chloride hexahydrate is weighed and the volume is adjusted to 250 ml, and the aluminum concentration is 2.44-3.66 g / L.

[0023] Furthermore, the operating parameters include radio frequency power, plasma gas flow rate, and auxiliary gas flow rate, wherein the radio frequency power is 1200-1600 watts, the plasma gas flow rate is 8-16 L / min, and the auxiliary gas flow rate is 0.3-0.5 L / min.

[0024] The specific method of drawing the standard curve is to inject calcium and copper standard working solutions of a series of concentrations in sequence, record the emission spectrum intensity of each element, and draw the standard curve with concentration as the horizontal axis and emission spectrum intensity as the vertical axis.

[0025] The specific method of sample determination is to inject the sample solution prepared in step 1, record the emission spectrum intensity of calcium and copper elements, and calculate the content of calcium and copper in the sample according to the standard curve.

[0026] The present invention has the following beneficial effects:

[0027] 1. Given that there are currently no public reports on analytical methods for the calcium and copper contents in catalyst additives, the present invention can fill this gap. According to the test method of the present invention, compared with traditional methods, there is no need to use expensive iodine and potassium iodide reagents, and calcium and copper can be determined simultaneously, saving resources, reducing costs, and improving analysis efficiency.

[0028] 2. Compared with the traditional method, the present invention can completely dissolve the insoluble catalyst by combining high temperature dissolution with ICP determination, and effectively avoid the low data caused by incomplete dissolution of the carrier aluminum wrapped around calcium and copper.

[0029] 3. The present invention effectively avoids the interference of the aluminum matrix by adding matrix aluminum. Through the matrix aluminum experiment, it is confirmed that the aluminum element interferes with the determination of calcium and copper. The addition of matrix aluminum masks the interference of excessive aluminum content in the catalyst on the determination of calcium and copper content.

[0030] 4. The acid addition experiment of the present invention solves the problem of the difficulty in dissolving calcium aluminum compounds in the catalyst.

[0031] 5. The relative standard deviation (RSD, n=7) of the calcium and copper content determination results of the present invention is less than 1.88%, the spiked recovery rate is between 100% and 103%, and the matrix interference in the catalyst is shielded, so the analytical method has high accuracy. BRIEF DESCRIPTION OF THE DRAWINGS

[0032] Figure 1 is a flow chart of the method of the present invention; DETAILED DESCRIPTION

[0033] The technical solution of the present invention is described clearly and completely below with reference to the accompanying drawings. It is apparent that the embodiments described are only a portion of the embodiments of the present invention, not all of them. All other embodiments derived by persons of ordinary skill in the art based on the embodiments of the present invention without inventive effort are intended to fall within the scope of protection of the present invention.

[0034] In addition, the technical features involved in different embodiments of the present invention described below can be combined with each other as long as they do not conflict with each other.

[0035] like Figure 1 Shown is a flow chart of the assay method of the present invention.

[0036] Example 1

[0037] Test on the influence of matrix aluminum

[0038] Weigh 2.472g of aluminum chloride hexahydrate, dilute to 100ml, and prepare aluminum chloride solution. Select standard samples with a calcium content of 100μg / ml and a copper content of 100μg / ml. Pipette 10ml of standard samples into 4 groups respectively, and add 5ml, 10ml, 15ml, 20ml, and 25ml of aluminum chloride solution to each group of samples in turn, and dilute to 100ml. After dilution, the sample is injected into the ICP test chamber to measure the intensity. Turn on the ICP-OES instrument, ignite the plasma, and after preheating and stabilization, optimize the instrument operating parameters: RF power of 1400W, plasma gas flow rate of 10L / min, nebulizer flow rate of 0.7L / min, auxiliary gas flow rate of 0.3L / min, and integration time of 2s. The effect of aluminum matrix on the determination of calcium and copper content was tested. The results are shown in Table 1. The aluminum matrix has an effect on the determination. The corresponding content of aluminum matrix is ​​added to the standard solution.

[0039] Table 1 Results of aluminum matrix interference test for determination of calcium and copper content

[0040]

[0041] Example 2

[0042] Drawing of the standard curve

[0043] Preparation of standard solution: Weigh 6.18 g of aluminum chloride hexahydrate and dilute to 250 ml to prepare an aluminum matrix. Pipette 0 ml, 5 ml, 10 ml, 15 ml, and 20 ml of the standard stock solutions of calcium and copper containing 100 mg / L, respectively, add 4 ml of the aluminum matrix, and dilute to 100 ml to prepare a series of standard working solutions with concentrations of 0 mg / L, 5 mg / L, 10 mg / L, 15 mg / L, and 20 mg / L.

[0044] Instrument conditions: Turn on the ICP-OES instrument, ignite the plasma, and after preheating and stabilization, optimize the instrument operating parameters: RF power of 1400 W, plasma gas flow rate of 10 L / min, nebulizer flow rate of 0.7 L / min, auxiliary gas flow rate of 0.3 L / min, and integration time of 2 s.

[0045] Standard curve drawing: inject calcium and copper standard working solutions with a series of concentrations in sequence, record the emission spectrum intensity of each element, and draw a standard curve with concentration as the horizontal axis and emission spectrum intensity as the vertical axis.

[0046] Example 3

[0047] Select the third group of standard samples (10 mg / L) in Example 2. Unlike Example 2, the operating parameters of the ICP instrument are: turn on the ICP-OES instrument, ignite the plasma, and after preheating and stabilization, optimize the instrument operating parameters: the radio frequency power is 1400 W, the plasma gas flow rate is set to 8 L / min, 10 L / min, 12 L / min, 14 L / min, and 16 L / min, the atomizer flow rate is 0.7 L / min, the auxiliary gas flow rate is 0.3 L / min, the integration time is 2 s, and the measurement wavelength copper is selected at 327 nm, 324 nm, and 224 nm; calcium is selected at 317 nm and 315 nm. The response intensity of calcium and copper is measured, and the optimal flow rate is selected. As shown in Table 2, the experimental results show that the plasma gas flow rate is set to 8-10 L / min, the copper wavelength is 324 nm, and the calcium copper intensity reaches the optimal condition when the calcium wavelength is 317 nm.

[0048] Table 2 Test results of calcium and copper determination instrument operating conditions

[0049]

[0050] Example 4

[0051] Acid dosage experiment

[0052] Select a standard sample with a calcium oxide content of 17% and a copper oxide content of 7.6%. Take 10g of the sample and grind it thoroughly so that all the samples pass through a 75μm test sieve. Accurately weigh approximately 0.15g of the sample into 6 groups, with 2 samples in each group. Add the acid dosage according to the table below to the sample in sequence. Place it on a hot plate and heat it at 400℃ for 30 minutes. Cool it to room temperature and adjust the volume to 1000ml. After adjusting the volume, the sample is measured by ICP injection. Turn on the ICP-OES instrument, ignite the plasma, and after preheating and stabilization, optimize the instrument operating parameters: RF power of 1400W, plasma gas flow rate of 10L / min, nebulizer flow rate of 0.7L / min, auxiliary gas flow rate of 0.3L / min, and integration time of 2s. The copper wavelength is 324nm and the calcium wavelength is 317nm.

[0053] The effects of the type and volume fraction of sulfuric acid on the determination of calcium and copper content were tested. The results are shown in Table 3. The optimal amount of acid added is 10ml-12ml. Sulfuric acid and phosphoric acid are preferred, as they are more convenient to operate.

[0054] Table 3 Effect of acid selection on calcium and copper content determination values

[0055]

[0056] Example 5

[0057] Accuracy experiment

[0058] Select standard samples with a calcium oxide content of 17% and a copper oxide content of 7.6%. Take 10g of the sample and grind it thoroughly so that all the samples pass through a 75μm test sieve. Accurately weigh 7 groups of about 0.15g of the sample, add 5ml of sulfuric acid and 5ml of phosphoric acid, place it on a hot plate and heat it at 400℃ for 30min, cool it to room temperature and dilute it to 1000ml. After diluting, the sample was ICP injected and measured. The ICP-OES instrument was turned on and the plasma was ignited. After preheating and stabilization, the instrument operating parameters were optimized: the radio frequency power was 1400W, the plasma gas flow rate was 10L / min, the atomizer flow rate was 0.7L / min, the auxiliary gas flow rate was 0.3L / min, the integration time was 2s, the copper determination wavelength was 324nm, and the calcium determination wavelength was 317nm. The results of the 7 groups of data are shown in Table 4 below. The relative standard deviation of calcium oxide was 1.2%, and the relative standard deviation of copper oxide was 1.88%. The method has good stability.

[0059] Table 4 Calcium and copper content of catalysts

[0060]

[0061]

[0062] Example 6

[0063] Spike recovery experiment

[0064] Select the heating aid sample, take 10g of the sample and grind it thoroughly so that all the samples pass through a 75μm test sieve. Accurately weigh about 0.15g of the sample in 8 groups, add 5ml of sulfuric acid and 5ml of phosphoric acid respectively, place it on a hot plate and heat it at 400℃ for 30min, cool it to room temperature and stabilize it. Four of the groups are fixed to 1000ml. The other four groups are added with 5ml of 100mg / L standard solution containing calcium and copper elements. According to the ICP injection measurement of the fixed volume sample, start the ICP-OES instrument, ignite the plasma, preheat and stabilize it, and optimize the instrument operating parameters: RF power of 1400W, plasma gas flow rate of 10L / min, nebulizer flow rate of 0.7L / min, auxiliary gas flow rate of 0.3L / min, integration time of 2s, copper determination wavelength of 324nm, calcium determination wavelength of 317nm. The measurement results of 8 groups of data are shown in Table 5 below. The average unspiked copper content is 5.92%, and the average calcium content is 9.58%. The spiked amount is calculated based on the Chengyang amount to be 0.148%. The spiked recovery rates are 102.5% for copper and 100.7% for calcium.

[0065] Table 5 Spike recovery experiment

[0066]

[0067] While embodiments of the present invention have been shown and described, it will be appreciated by those skilled in the art that various changes, modifications, substitutions, and variations may be made to these embodiments without departing from the principles and spirit of the invention, and that the scope of the invention is defined by the appended claims and their equivalents.

[0068] The above specific implementation methods are detailed descriptions of the present invention. It cannot be considered that the specific implementation methods of the present invention are limited to these descriptions. For ordinary technicians in the technical field to which the present invention belongs, they can make several simple deductions and substitutions without departing from the concept of the present invention, which should be regarded as falling within the scope of protection of the present invention.

Claims

1. A method for determining the content of calcium and copper in a catalyst promoter, characterized in that: The following steps are involved: Step 1: Weigh the catalyst additive sample, add the mixed acid, heat and dissolve, cool to room temperature, dilute to volume, shake well and set aside; Step 2: Add aluminum matrix to the standard solutions of calcium and copper elements respectively, and dilute them step by step to form a series of standard working solutions; Step 3: Adjust instrument operating parameters; Step 4: draw the standard curve; Step 5: Sample measurement.

2. The method for determining the calcium and copper contents in a catalyst promoter according to claim 1, wherein: In step 1, the mixed acid is a combination of two or three of phosphoric acid, sulfuric acid, hydrochloric acid and nitric acid.

3. The method for determining the calcium and copper contents in a catalyst promoter according to claim 2, wherein: The volume of the phosphoric acid is 0-10 ml, the volume of the sulfuric acid is 0-10 ml, the volume of the nitric acid is 0-5 ml, the volume of the hydrochloric acid is 0-10 ml, and the total amount of the mixed acid is 10 ml-12 ml.

4. The method for determining the calcium and copper contents in a catalyst promoter according to claim 3, wherein: Preferably, the volume of phosphoric acid is 5 ml and the volume of sulfuric acid is 5 ml.

5. The method for determining the calcium and copper contents in a catalyst promoter according to claim 1, wherein: In step 1, the catalyst additive sample needs to be ground and sieved, and the mesh diameter of the sieve is 200-220 mesh.

6. The method for determining the calcium and copper contents in a catalyst promoter according to claim 1, wherein: In step 1, the sample amount is 100 mg-150 mg, the heating temperature is 350-400° C., and the heating time is 30 min.

7. The method for determining the calcium and copper contents in a catalyst promoter according to claim 1, wherein: In step 2, when preparing the diluted concentrations of calcium and copper element standard solutions, the amount of matrix aluminum added is based on the aluminum content in the sample. By mass ratio, the matrix aluminum in the diluted concentrations of calcium and copper element standard solutions: aluminum in the sample is 1:0.9-1.

1.

8. The method for determining the calcium and copper contents in a catalyst promoter according to claim 1, wherein: The working parameters include RF power, plasma gas flow rate, and auxiliary gas flow rate, among which the RF power is 1200-1600 watts, the plasma gas flow rate is 8-16 L / min, and the auxiliary gas flow rate is 0.3-0.5 L / min.

Images