Method for determining metal elements in zirconocene
By treating the zirconium dicetyl samples with a mixture of sodium hydroxide and sodium carbonate, soluble zirconate and leaching with organic acid, the accuracy of the determination of metal element content in zirconium dicetyl was solved, and stable and reliable test results were achieved.
Patent Information
- Application Number
- CN202510626354.5
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2025-05-15
- Publication Date
- 2025-07-29
AI Technical Summary
The prior art is difficult to accurately determine the content of metal elements in zirconium dicetopes, especially the content of zirconium, hafnium, iron, nickel, and copper, and inductively coupled plasma emission spectrometry has the problem of unstable results when detecting insoluble samples.
The mixture of sodium hydroxide and sodium carbonate was used as alkaline flux, and the zirconium dicetyl samples were treated by low-temperature pretreatment and high-temperature melting to produce soluble zirconate, which was then leaching with an organic acid solution, and finally measured by inductively coupled plasma method.
The stable determination of the metal element content in zirconium dichotomy is achieved, the accuracy and reliability of the test results are improved, the use of inorganic acid is reduced, and the safety of the instrument and the environment is protected.
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Abstract
Description
Technical Field
[0001] The present invention belongs to the technical field of element detection, and particularly relates to a method for determining metal elements in zirconocene dichloride. Background Art
[0002] Zirconocene dichloride is a metal-organic compound, which belongs to metallocene compounds, and the central metal atom therein is zirconium (Zr). The ligand is two cyclopentadienyl groups (C5H5, abbreviated as Cp). The zirconium atom is in the central position and is sandwiched between two cyclopentadienyl groups in a π-coordination manner, forming a typical sandwich structure. In the synthesis of polymer materials, zirconocene dichloride is used as a catalyst for synthesizing high-performance polyolefin materials. It can precisely control the molecular structure of the polymer, such as molecular weight, degree of branching, etc. The polyolefin materials synthesized by using zirconocene dichloride catalyst have better mechanical properties, thermal stability and chemical stability, and can be used for manufacturing high-performance plastic products, fibers, etc.
[0003] In the structure of zirconocene dichloride, the zirconium atom plays a core role. Its empty orbitals can form coordination bonds with reactant molecules, thereby activating the reactants and making them more likely to react. The zirconium content also affects the performance of zirconocene dichloride. In catalytic applications, an appropriate zirconium content can ensure the catalytic activity of zirconocene dichloride. If the zirconium content is too low, it may lead to a decrease in the efficiency of the catalytic reaction and the inability to effectively initiate the reaction; while too high a zirconium content may trigger some side reactions because too many zirconium centers may cause changes in the selectivity of the reaction and affect the quality of the final product. Zirconocene dichloride compounds are used in high-precision catalytic reactions or the preparation of materials with extremely high purity requirements. In addition to zirconium, other metal ions, such as hafnium from raw materials or metal impurities such as iron, nickel, and copper in reaction vessels. These metal impurities may affect the selectivity and activity of zirconocene dichloride in certain catalytic reactions. For example, in the catalytic olefin polymerization reaction, a small amount of hafnium may change the polymerization reaction rate and the molecular weight distribution of the polymer.
[0004] Determining the element content by inductively coupled plasma emission spectrometry has the advantages of simple operation, strong specificity, few interferences, etc., but it is mainly used for the detection of soluble samples. Zirconium is a poorly soluble metal. If the sample cannot be completely digested, it will lead to unstable test results of zirconium or other trace elements and low test results. Moreover, zirconocene dichloride is an organic substance and cannot be completely digested by acid dissolution and microwave digestion. Therefore, alkali fusion is required for testing. Since zirconocene dichloride is an organic substance, the reaction is very violent during its melting process, resulting in the ejection of the sample. Therefore, it is particularly important to explore a simple and accurate method for determining the metal content in zirconocene dichloride. Summary of the Invention
[0005] To overcome the problems in the prior art, the present invention provides a method for determining metal elements in zirconocene, with a simple and accurate detection method, capable of accurately detecting the contents of Zr, Hf, Fe, Ni, Cu, etc. in zirconocene by inductively coupled plasma emission spectrometry.
[0006] To solve the above technical problems, the technical solution proposed by the present invention is as follows: The present invention provides a method for determining metal elements in zirconocene, comprising the following steps: S1. Evenly spread an alkaline flux and zirconocene on the bottom of a heatable container, and heat the heatable container at a low temperature until zirconocene is in a semi-molten state. After no violent thermal reaction, continue to heat up to a fully molten state above 600 °C, and then cool to obtain a melt block; the alkaline flux is a mixture of sodium hydroxide and sodium carbonate.
[0007] S2. Add an organic acid solution to the heatable container containing the melt block obtained in step S1, heat until the melt block is completely dissolved to obtain a concentrated solution, transfer the concentrated solution to a corrosion-resistant container, add an acidic solution and then heat to boiling again, and cool to room temperature to obtain a test solution.
[0008] S3. Dilute the test solution obtained in step S2 to a fixed volume, and use inductively coupled plasma method for determination, and then the contents of metal elements in zirconocene can be obtained.
[0009] In the present invention, first, a mixed alkaline flux of sodium hydroxide and sodium carbonate is used to pretreat the sample at a low temperature, so that it will not splash during subsequent high-temperature melting, which may lead to unstable final test results. After melting and cooling, subsequent treatment is carried out, otherwise there are safety hazards in subsequent steps. Secondly, zirconocene in the present invention is an organic substance. If sodium peroxide is used as a flux, it will cause violent reaction during melting, the crucible will burst and the sample will splash. And sodium hydroxide has strong water absorption, and the melting temperature and time need to be strictly controlled. Too long melting time or too high temperature will cause the molten sample to climb up the crucible wall and splash outside the crucible wall, increasing the difficulty of test operation. Using sodium carbonate alone requires long-term melting at 1000 °C, and the test results are on the low side. In the present invention, a mixture of sodium hydroxide and sodium carbonate is used as the alkaline flux, and the melting temperature reaches above 600 °C, so that the zircon in zirconocene can be converted into soluble zirconate. Aiming at the easy hydrolysis characteristic of zirconate, organic acid is used for leaching. On the one hand, it can effectively prevent the hydrolysis of zirconium and hafnium in the sample, and on the other hand, it can reduce the usage amount of subsequent inorganic acid. Inorganic acid has strong volatility, and a large amount of use will cause great harm to instruments, human bodies and the environment. Then, an acidic solution is used for acidification, pipetting and volume fixing, dilution, and finally the inductively coupled plasma method is used to determine the contents of Zr, Hf, Fe, Ni, Cu in the solution.
[0010] As an alternative embodiment, in the method provided by the present invention, in step S1, the mass ratio of sodium hydroxide to sodium carbonate in the basic flux is (2-4):1.
[0011] As an alternative embodiment, in the method provided by the present invention, in step S1, the mass ratio of the basic flux to zirconocene is (3-4):(0.1-0.3).
[0012] In the present invention, the masses of the basic flux and zirconocene are beneficial to the stability of the test results and to increasing the service life of the inductively coupled plasma emission spectrometer.
[0013] As an alternative embodiment, in the method provided by the present invention, in step S1, the heatable container is first heated to 200-500 °C, held at a constant temperature for melting for 10-30 min, and then heated to 650-750 °C, held at a constant temperature for melting for 10-20 min.
[0014] As an alternative embodiment, in the method provided by the present invention, in step S2, the organic acid is selected from one or more of citric acid, tartaric acid, or oxalic acid.
[0015] As an alternative embodiment, in the method provided by the present invention, in step S2, the concentration of the organic acid is 50-100 g / L, and the mass ratio of the organic acid to zirconocene is (2.5-5.0):(0.1-0.3).
[0016] As an alternative embodiment, in the method provided by the present invention, in step S2, the acidic solution is selected from one or more of hydrochloric acid, nitric acid, hydrofluoric acid, or sulfuric acid.
[0017] As an alternative embodiment, in the method provided by the present invention, in step S3, the metal elements in zirconocene include Zr, Hf, Fe, Ni, and Cu.
[0018] As an alternative embodiment, in the method provided by the present invention, in step S2, the mass ratio of the added acidic solution to the basic flux is (7-10):1.
[0019] Compared with the prior art, the beneficial effects of the present invention are: In the present invention, a mixed reagent of sodium hydroxide and sodium carbonate is used as a flux, and then it is pretreated at a low temperature so that it will not splash during subsequent high-temperature melting, which may lead to unstable final test results. The melting temperature needs to reach above 600 °C so that zirconium in zirconocene can be converted into soluble zirconate. After melting, an organic acid solution is used as an extractant, which can effectively prevent the hydrolysis of Zr and Hf in the subsequent process and reduce the large amount of inorganic acid used later. Finally, it is acidified with an acidic solution, transferred to a volumetric flask for volume fixation, diluted, and then the inductively coupled plasma method is used to determine the contents of Zr, Hf, Fe, Ni, and Cu in the solution. Detailed implementation manners
[0020] To facilitate the understanding of the present invention, the following will describe the present invention more comprehensively and meticulously in conjunction with the specification and preferred embodiments. However, the protection scope of the present invention is not limited to the following specific embodiments.
[0021] Unless otherwise defined, all the professional terms used hereinafter have the same meanings as commonly understood by those skilled in the art. The professional terms used herein are only for the purpose of describing specific embodiments and are not intended to limit the protection scope of the present invention.
[0022] Unless otherwise specifically stated, all kinds of raw materials, reagents, instruments, and equipment used in the present invention can be obtained through market purchase or can be prepared by existing methods.
[0023] Determining the contents of Zr, Hf, Fe, Ni, and Cu in a liquid by inductively coupled plasma emission spectrometry specifically means: Measuring the intensity values of multiple groups of solutions with known concentrations of Zr, Hf, Fe, Ni, and Cu by an inductively coupled plasma emission spectrometer. Taking the concentration and intensity value of the solution as the two coordinate axes of a two-dimensional coordinate system respectively, putting the concentrations and corresponding intensity values of Zr, Hf, Fe, Ni, and Cu in multiple groups of known-concentration mixed solutions into the two-dimensional coordinate system to obtain multiple coordinate points, and plotting the standard curve of element concentration and intensity value.
[0024] Measuring the intensity value of the liquid in a volumetric flask at the wavelengths of Zr, Hf, Fe, Ni, and Cu by an inductively coupled plasma emission spectrometer, and substituting this intensity value into the appropriate standard curve of element concentration and intensity value to obtain the concentrations of Zr, Hf, Fe, Ni, and Cu in the liquid of this volumetric flask.
[0025] According to the element concentrations in the liquid of the volumetric flask, the fixed volume of the liquid in the volumetric flask, the dilution factor of the liquid in the volumetric flask, and the mass of the sample, the contents of Zr, Hf, Fe, Ni, and Cu in the sample are obtained.
[0026] According to the element contents, the standard curves of element concentration and intensity value include the following three types: The first method: Accurately pipette 0.00 mL, 0.20 mL, 0.50 mL, 1.0 mL, 2.0 mL, 5.0 mL of standard stock solution 1 into volumetric flasks respectively, successively add appropriate reagent blank stock solution, dilute to the mark with water, mix well, zero with water, measure the intensity value of the metal element, use the metal element concentration as the abscissa and the intensity value of the element as the ordinate to plot the standard curve of the metal element.
[0027] The second method: Accurately pipette 0.50 mL, 1.0 mL, 2.0 mL, 5.0 mL, 10.0 mL of standard solution into volumetric flasks respectively, successively add appropriate reagent blank stock solution, dilute to the mark with water, mix well, zero with water, measure the intensity value of the metal element, use the metal element concentration as the abscissa and the intensity value of the element as the ordinate to plot the standard curve of the metal element.
[0028] The third method: Accurately pipette 1. mL, 2.0 mL, 3.0 mL, 4.0 mL, 5.0 mL of standard stock solution 2 into volumetric flasks respectively, successively add appropriate reagent blank stock solution, dilute to the mark with water, mix well, zero with water, measure the intensity value of the metal element, use the metal element concentration as the abscissa and the intensity value of the metal element as the ordinate to plot the standard curve.
[0029] When determining the content of metal elements in the volumetric flask liquid by inductively coupled plasma emission spectrometry, when the concentration of the metal element is less than or equal to 0.5 mg / L, the first standard curve is used for calculation; when the concentration is greater than 0.5 mg / L and less than or equal to 10.0 mg / L, the second standard curve is used for calculation; when the concentration is greater than 10.0 mg / L, the third standard curve is used for calculation.
[0030] Zr, Hf, Fe, Ni, Cu standard stock solution 1: Commercially available certified standard solution with a concentration of 10.0 mg / L.
[0031] Zr, Hf, Fe, Ni, Cu standard stock solution 2: Commercially available certified standard solution with a concentration of 1000 mg / L.
[0032] Zr, Hf, Fe, Ni, Cu standard solution: Pipette 10 mL of the above standard stock solution 1 into a 100 mL volumetric flask, dilute to the mark with water, mix well. This solution contains 100 μg of element content per 1 mL.
[0033] According to the concentrations of Zr, Hf, Fe, Ni, Cu in the volumetric flask liquid, the fixed volume of the liquid in the volumetric flask, the dilution factor of the liquid in the volumetric flask and the mass of the sample, the contents of Zr, Hf, Fe, Ni, Cu in the sample are obtained. Specifically, it means: Calculate the contents of Zr, Hf, Fe, Ni, and Cu in the liquid sample of the volumetric flask according to the following formula:
[0034] wherein, is the mass fraction of Zr, Hf, Fe, Ni, and Cu, expressed as a percentage (%); c is the concentration of Zr, Hf, Fe, Ni, and Cu in the liquid of the volumetric flask obtained from the standard curve, with the unit of μg / mL; V is the fixed volume of the liquid in the volumetric flask, with the unit of mL; f is the dilution factor of the liquid in the volumetric flask; m is the mass of the sample, with the unit of g.
[0035] Example 1 A method for determining metal elements in zirconocene dichloride, the steps are as follows: Step 1. Sample melting: Weigh 1.0 g of a mixture of sodium hydroxide and sodium carbonate (2:1) and evenly spread it on the bottom of the crucible. Then weigh 0.1 g of the sample and spread it evenly on top. Then weigh 2.0 g of the mixture of sodium hydroxide and sodium carbonate (2:1) to cover the sample. Place it in a muffle furnace, heat from room temperature to 300 °C, then keep it at a constant temperature for melting for 10 min, then heat up to 750 °C, keep it at a constant temperature for melting for 10 min, then turn off the power, open the furnace door, and take it out after cooling.
[0036] Step 2. Horizontally place the crucible into a cup made of about 350 mL of polytetrafluoroethylene material, add 50 mL of citric acid solution (100 g / L), cover it with a watch glass, heat it to boiling on a hot plate. After heating until all the fused mass is dissolved and the volume is concentrated to about 35 mL, remove the beaker, wash out the crucible, then add 20 mL of hydrochloric acid to the beaker, heat it to boiling again, remove it and cool it to room temperature, then transfer it to a 100 ml volumetric flask, dilute it to the scale with water, and mix well.
[0037] Step 3. Pipette 5 mL of the solution from the 100 mL volumetric flask in Step 2 into a 50 mL volumetric flask, make up the volume, shake well, dilute it to the scale with water, and mix well. Use the inductively coupled plasma method for determination. By using the above method for determination, the contents of Zr, Hf, Fe, Ni, and Cu in the sample can be obtained. The test results are shown in Table 1 below. It can be seen from Table 1 that the test results of the metal elements in zirconocene dichloride by using the present invention are consistent with the theoretical values, and the test results are stable and reliable.
[0038] Table 1: Test results in Example 1
[0039] Example 2 Step 1. Sample melting: Weigh 1.0 g of the sodium hydroxide and sodium carbonate mixture (4:1) and evenly spread it on the bottom of the crucible. Then weigh 0.3 g of the sample and spread it flat on top. Next, weigh 3.0 g of the sodium hydroxide and sodium carbonate mixture (4:1) and cover the sample. Place it in a muffle furnace, heat it from room temperature to 300 °C, then keep it at a constant temperature for melting for 10 min, then heat it up to 650 °C, keep it at a constant temperature for melting for 20 min, then turn off the power, open the furnace door, and take it out after cooling.
[0040] Step 2. Horizontally place the crucible into a beaker made of about 350 mL of polytetrafluoroethylene material, add 50 mL of citric acid solution (50 g / L), cover it with a watch glass, heat it to boiling on a hot plate, heat until all the fused mass is dissolved, and the volume is concentrated to about 35 mL. Remove the beaker, wash out the crucible, then add 40 mL of hydrochloric acid to the beaker, heat it to boiling again, remove it and cool it to room temperature, then transfer it to a 100 ml volumetric flask, dilute it to the mark with water, and mix well.
[0041] Step 3. Pipette 5 mL of the solution from the 100 mL volumetric flask in Step 2 into a 50 mL volumetric flask, make up the volume, shake well, dilute it to the mark with water, and mix well. Use inductively coupled plasma method for determination. By using the above method for determination, the contents of Zr, Hf, Fe, Ni, and Cu in the sample can be obtained. The test results are shown in Table 2 below. It can be seen from Table 2 that the test results of the metal elements in zirconocene dichloride by using the present invention are consistent with the theoretical values, and the test results are stable and reliable.
[0042] Table 2: Test results in Example 2
[0043] Comparative Example 1 Step 1. Sample melting: Weigh 1.0 g of the sodium hydroxide and sodium carbonate mixture (2:1) and evenly spread it on the bottom of the crucible. Then weigh 0.1 g of the sample and spread it flat on top. Next, weigh 2.0 g of the sodium hydroxide and sodium carbonate mixture (2:1) and cover the sample. Place it in a muffle furnace at 750 °C, keep it at a constant temperature for melting for 10 min, then turn off the power, open the furnace door, and take it out after cooling.
[0044] Step 2. Horizontally place the crucible into a beaker made of about 350 mL of polytetrafluoroethylene material, add 50 mL of citric acid solution (100 g / L), cover it with a watch glass, heat it to boiling on a hot plate, heat until all the fused mass is dissolved, and the volume is concentrated to about 35 mL. Remove the beaker, wash out the crucible, then add 20 mL of hydrochloric acid to the beaker, heat it to boiling again, remove it and cool it to room temperature, then transfer it to a 100 ml volumetric flask, dilute it to the mark with water, and mix well.
[0045] Step 3: Transfer 5 mL of the solution from the 100 mL volumetric flask in Step 2 to a 50 mL volumetric flask, make up the volume to the mark with water, shake well, dilute to the scale, mix evenly, and perform the determination using inductively coupled plasma method. By performing the determination using the above method, the contents of Zr, Hf, Fe, Ni, and Cu in the sample can be obtained. The comparison of the test results between Comparative Example 1 and Example 1 is shown in Table 3 below.
[0046] Table 3: Comparison of Test Results between Comparative Example 1 and Example 1
[0047] As can be seen from Table 3, directly melting zirconocene with an alkaline flux causes a violent reaction during the melting process, and the sample splashes severely, resulting in unstable test results. Therefore, it is necessary to perform low-temperature pretreatment first and then high-temperature melting during the melting process.
[0048] Comparative Example 2 Step 1: Sample melting: Weigh 1.0 g of a mixture of sodium hydroxide and sodium carbonate (2:1) and spread it evenly on the bottom of the crucible. Then weigh 0.1 g of the sample and spread it on top, and then weigh 2.0 g of the mixture of sodium hydroxide and sodium carbonate (2:1) to cover the sample. Place it in a muffle furnace, heat from room temperature to 300 °C, then keep it at a constant temperature for melting for 10 min, then heat up to 550 °C, keep it at a constant temperature for melting for 10 min, then turn off the power, open the furnace door, and take it out after cooling.
[0049] Step 2: Place the crucible horizontally into a beaker made of about 350 mL of polytetrafluoroethylene material, add 50 mL of citric acid solution (100 g / L), cover it with a watch glass, heat it to boiling on a hot plate, heat until all the melt is dissolved and the volume is concentrated to about 35 mL, remove the beaker, wash out the crucible, then add 20 mL of hydrochloric acid to the beaker, heat it to boiling again, remove it and cool it to room temperature, and then transfer it to a 100 ml volumetric flask, dilute to the scale with water, and mix evenly.
[0050] Step 3: Transfer 5 mL of the solution from the 100 mL volumetric flask in Step 2 to a 50 mL volumetric flask, make up the volume to the mark, shake well, dilute to the scale with water, mix evenly, and perform the determination using inductively coupled plasma method. By performing the determination using the above method, the contents of Zr, Hf, Fe, Ni, and Cu in the sample can be obtained. The comparison of the test results between Comparative Example 2 and Example 1 is shown in Table 4 below.
[0051] Table 4: Comparison of Test Results between Comparative Example 2 and Example 1
[0052] As can be seen from Table 4, zirconocene reacts with the alkaline flux during the alkali fusion process. Zirconium oxide may be formed during this process. Due to the too low temperature during the alkali fusion process, zirconium oxide cannot completely react with the alkaline flux to form zirconate soluble in hydrochloric acid, which significantly results in a low zirconium content.
[0053] Comparative Example 3 Step 1. Sample melting: Weigh 1.0 g of the mixture of sodium hydroxide and sodium carbonate (2:1) and spread it evenly on the bottom of the crucible. Then weigh 0.1 g of the sample and spread it on top. Then weigh 2.0 g of the mixture of sodium hydroxide and sodium carbonate (2:1) to cover the sample. Put it into the muffle furnace, heat it from room temperature to 300 °C, then keep it at a constant temperature for melting for 10 min, then raise the temperature to 750 °C, keep it at a constant temperature for melting for 10 min, then turn off the power supply, open the furnace door, and take it out after cooling.
[0054] Step 2. Horizontally place the crucible into a beaker made of about 350 mL of polytetrafluoroethylene material, add 50 mL of ultrapure water, cover it with a watch glass, heat it on a hot plate until boiling. After heating until all the melt is dissolved and the volume is concentrated to about 35 mL, remove the beaker, wash out the crucible, then add 20 mL of hydrochloric acid to the beaker, heat it to boiling again, remove it and cool it to room temperature, then transfer it to a 100 ml volumetric flask, dilute it to the mark with water, and mix well.
[0055] Step 3. Pipette 5 mL of the solution from the 100 mL volumetric flask in Step 2 into a 50 mL volumetric flask, make up the volume, shake well, dilute it to the mark with water, and mix well. Use the inductively coupled plasma method for determination. By using the above method for determination, the contents of Zr, Hf, Fe, Ni, and Cu in the sample can be obtained. The test results of Comparative Example 3 and Example 1 are compared as shown in Table 5 below.
[0056] Table 5: Comparison of test results between Comparative Example 3 and Example 1
[0057] The bonding energies of various oxygen-containing ligands with zirconium and hafnium are very close. Therefore, hydrolysis reactions can occur both in acidic solutions and in alkaline solutions, and the degree of hydrolysis is determined by the number of hydroxyl groups in the complex. In Comparative Example 3, a large amount of inorganic acid is used for acidification, and the use of a large amount of concentrated acid will cause serious harm to the instruments, experimental personnel, and detection environment. Therefore, in the present invention, in order to prevent hydrolysis and reduce the use of inorganic acid, citric acid is used for leaching during the leaching process. Zirconium and hafnium can form stable complexes with citric acid. Using this property, zirconium and hafnium can be prevented from precipitating out of the solution in the form of zirconium hydroxide and hafnium hydroxide. It can be clearly seen from Table 5 that the zirconium hydroxide (hafnium) produced by hydrolysis causes a series of metal elements to adsorb and precipitate on it, resulting in a low and unstable overall test result.
[0058] Comparative Example 4 Step 1. Sample melting: Weigh 1.0 g of sodium hydroxide and evenly spread it on the bottom of the crucible. Then weigh 0.1 g of the sample and lay it flat on top. Next, weigh 2.0 g of sodium hydroxide to cover the sample. Place it in a muffle furnace, heat it from room temperature to 300 °C, then keep it at a constant temperature for melting for 10 min. Then heat it up to 750 °C, keep it at a constant temperature for melting for 10 min, turn off the power supply, open the furnace door, and take it out after cooling.
[0059] Step 2. Horizontally place the crucible into a beaker made of polytetrafluoroethylene with a volume of about 350 mL, add 50 mL of citric acid solution (100 g / L), cover it with a watch glass, heat it on a hot plate until it boils. After heating until all the fused mass is dissolved and the volume is concentrated to about 35 mL, remove the beaker, wash out the crucible, then add 20 mL of hydrochloric acid to the beaker, heat it to boil again, remove it and cool it to room temperature, then transfer it to a 100 ml volumetric flask, dilute it with water to the scale, and mix well.
[0060] Step 3. Pipette 5 mL of the solution from the 100 mL volumetric flask in Step 2 into a 50 mL volumetric flask, make up the volume, shake well, dilute it with water to the scale, and mix well. Use inductively coupled plasma method for determination. By using the above method for determination, the contents of Zr, Hf, Fe, Ni, and Cu in the sample can be obtained. The comparison of the test results between Comparative Example 4 and Example 1 is shown in Table 6 below.
[0061] Table 6: Comparison of Test Results between Comparative Example 4 and Example 1
[0062] In Comparative Example 4, sodium hydroxide was used alone for melting zirconocene dichloride. During the melting process, the reaction was intense. Due to the strong water absorption of sodium hydroxide, it was easy to cause the molten sample to climb up the wall and outside the crucible wall during melting, resulting in a lower test result compared to Example 1 and poorer stability.
[0063] The above content is a further detailed description of the present invention in combination with specific preferred embodiments. It cannot be determined that the specific implementation of the present invention is only limited to these descriptions. For those of ordinary skill in the art to which the present invention pertains, without departing from the concept of the present invention, several simple deductions or substitutions can still be made, which should all be regarded as belonging to the protection scope of the present invention.
Claims
1. A method for determining the metal element in zirconocene, characterized in that, It includes the following steps: S1. Evenly spread the alkaline flux and zirconocene dichloride on the bottom of a heatable container. Heat the heatable container at a low temperature until zirconocene dichloride is in a semi-molten state. After no violent thermal reaction, continue to heat up to a fully molten state at a temperature above 600 °C, and then cool to obtain a fused mass; the alkaline flux is a mixture of sodium hydroxide and sodium carbonate; S2. Add an organic acid solution to the heatable container containing the fused mass obtained in step S1, heat until the fused mass is completely dissolved to obtain a concentrated solution, transfer the concentrated solution to a corrosion-resistant container, add an acidic solution and then heat to boiling again, and cool to room temperature to obtain a test solution; S3. Dilute the test solution obtained in step S2 to a fixed volume and use inductively coupled plasma method for determination, and then the content of metal elements in zirconocene dichloride can be obtained.
2. The method for determining the metal element in zirconocene according to claim 1, wherein In step S1, the mass ratio of sodium hydroxide to sodium carbonate in the alkaline flux is (2 - 4):
1.
3. The method for determining the metal element in zirconocene according to claim 1, characterized in that, In step S1, the mass ratio of the alkaline flux to zirconocene dichloride is (3 - 4):(0.1 - 0.3).
4. The method for determining the metal element in zirconocene according to claim 1, wherein In step S1, first heat the heatable container to 200 - 500 °C, keep it at a constant temperature for melting for 10 - 30 min, then heat up to 650 - 750 °C, and keep it at a constant temperature for melting for 10 - 20 min.
5. The method for determining the metal element in zirconocene according to claim 1, wherein In step S2, the organic acid is selected from one or more of citric acid, tartaric acid or oxalic acid.
6. The method for determining the metal element in zirconocene according to claim 1, wherein In step S2, the concentration of the organic acid is 50 - 100 g / L, and the mass ratio of the organic acid to zirconocene dichloride is (2.5 - 5.0):(0.1 - 0.3).
7. The method for determining the metal element in zirconocene according to claim 1, characterized in that, In step S2, the acidic solution is selected from one or more of hydrochloric acid, nitric acid or sulfuric acid.
8. The method for determining the metal element in zirconocene according to claim 1, characterized in that, In step S2, the mass ratio of the added acidic solution to the alkaline flux is (7 - 10):
1.
9. The method for determining the metal element in zirconocene according to claim 1, characterized in that, In step S3, the metal elements in zirconocene dichloride include one or several of Zr, Hf, Fe, Ni or Cu.