Method for testing content of phosphorus pentafluoride

Abstract

The invention discloses a method for testing the content of phosphorus pentafluoride, and belongs to the field of chemical detection. The detection process comprises the following steps: preparing mixed standard gas, and preparing to-be-detected sample gas; respectively connecting a gas steel cylinder for mixing the standard gas and the sample gas to be detected with a laser Raman spectrum gas analyzer; acquiring the characteristic peak intensity value of each component of the mixed standard gas, and calculating the response coefficient of the impurity gas relative to the nitrogen according to a formula 1; according to the obtained relative response coefficient, the peak intensity of the impurity gas relative to nitrogen is calculated through a formula 2, and finally the accurate percentage content of PF5 is calculated through a normalization method of a formula 3. Ri = psi nitrogen I miscellaneous / psi miscellaneous I nitrogen (1), INi = Ii / Ri (2), and psi = 100% INi / # imgabs0 # (3). According to the testing method, the content of each component in phosphorus pentafluoride can be accurately quantified, the situation that impurities cannot be separated from a main peak in gas chromatography is avoided, and the situation that main content calculation is inaccurate due to the fact that the content of diatomic molecules cannot be obtained in gas infrared detection is also avoided.

Description

Technical Field

[0001] The present application belongs to the field of chemical detection, and specifically relates to a method for testing the content of phosphorus pentafluoride. Background Art

[0002] Phosphorus pentafluoride (PF5) is an inorganic compound that is a colorless to light yellow gas or liquid with a pungent odor. PF5 is gaseous at room temperature and pressure, but can be liquefied under a certain pressure, with a melting point of -93.8°C and a boiling point of -84.6°C. PF5 will violently smoke in humid air, produce toxic and corrosive hydrofluoric acid, and easily hydrolyze and ammonolyze. PF5 is a strong oxidizing agent and fluorinating agent that can react with many substances. It can react with water to produce hydrofluoric acid and phosphoric acid, react with alkali to produce corresponding fluorides and phosphates, and react with alcohol to produce alkyl fluorides and phosphate esters. In addition, phosphorus pentafluoride can also react with some metal and non-metal elements to form corresponding metal fluorides and non-metal fluorides.

[0003] PF5 is widely used in the fields of chemical industry, catalyst, electronics industry, new energy, etc. PF5 has a wide range of applications in the chemical industry. It can be used as a semiconductor dopant, chemical reagent, organic synthesis catalyst, etc. In the semiconductor manufacturing process, phosphorus pentafluoride is used as a dopant to improve the performance of semiconductor materials. In addition, it can also be used as a catalyst for many copolymerization reactions, such as the copolymerization of glucose anhydride and dehydrated mannitol; metal oxides treated with PF5 can promote the conversion of hydrocarbon compounds, such as the reaction of tributyltoluene to toluene. PF5 also plays an important role in the electronics industry. It can be used to manufacture high-purity electronic components and materials, such as semiconductor devices, integrated circuits, etc. These components and materials are essential to the performance and reliability of modern electronic equipment. PF5 is used in the synthesis of lithium hexafluorophosphate in the new energy industry, and hexafluoro has become the main component of commercial electrolytes. In addition to the above fields, PF5 also has certain applications in other fields. For example, it can be used to manufacture high-performance lubricants and greases to improve the working efficiency and life of mechanical equipment. In addition, phosphorus pentafluoride can also be used to manufacture certain special optical materials and laser materials.

[0004] It can be seen that PF5 has a wide range of uses. Currently, the main methods for detecting the content of PF5 are gas phase detection and infrared spectroscopy. In gas phase detection, the synthesis process of PF5 contains many impurities, such as phosphorus oxyfluoride (POF3), hydrogen fluoride (HF), phosphorus trifluoride (PF3), oxygen (O2), and hydrogen fluoride (HCl). These substances are difficult to achieve complete baseline separation in a corrosion-resistant gas phase separation system, which affects the quantification of high-purity PF5. In gas infrared detection, since diatomic gases cannot be detected, accurate quantification of PF5 cannot be achieved. Gas Raman detection can detect almost all gases (except inert gases), making it a feasible method for detecting high-purity PF5. Summary of the invention

[0005] The object of the present invention is to provide a method for testing the content of phosphorus pentafluoride (PF5) to solve the problem of accurate quantification in existing detection methods.

[0006] To achieve the above object, the present invention adopts the following technical solution:

[0007] A method for testing the content of phosphorus pentafluoride, the process is as follows:

[0008] (1) Prepare mixed standard gas and sample gas to be tested;

[0009] (2) Connecting the gas cylinders of the mixed standard gas and the sample gas to be tested to the laser Raman spectrometer gas analyzer respectively;

[0010] (3) Obtain the characteristic peak intensity value of each component of the mixed standard gas and calculate the response coefficient of each impurity gas relative to nitrogen; based on the obtained relative response coefficient, calculate the peak intensity of each impurity gas relative to nitrogen, and finally calculate the accurate percentage content of PF5 by normalization method.

[0011] Furthermore, the response coefficient of each impurity gas relative to nitrogen is calculated according to the following formula 1:

[0012] R i =ψ 氮 I 杂 / ψ 杂 I 氮 (1)

[0013] R i Represents the relative response coefficient of impurity gas, ψ 氮 and ψ 杂 Represent the volume fractions of nitrogen and impurity gases, I 氮 and I 杂 Represent the peak intensities of nitrogen and impurity gases, respectively.

[0014] Furthermore, the peak intensity of each impurity gas relative to nitrogen is calculated according to the following formula 2:

[0015] I Ni =I i / R i (2)

[0016] I Ni Represents the peak intensity when a certain impurity gas in the entire flow cell of the laser Raman spectroscopy gas analyzer is completely converted into nitrogen. i is the actual peak intensity of a certain impurity gas, R i Indicates the relative response coefficient of the impurity gas.

[0017] Furthermore, the exact percentage of PF5 is calculated according to the normalization method of the following formula 3:

[0018]

[0019] Furthermore, the mixed standard gas is a mixture of nitrogen and impurity gas, the impurity gas is at least one of O2, HF, HCl, POF3 and PF5, and the impurity gas accounts for 0.5-10% of the volume of the mixed standard gas.

[0020] Furthermore, in step (2), the laser Raman spectroscopic gas analyzer is equipped with two air inlet pipelines, one for purge gas and the other for mixed standard gas or sample gas. The two air inlet pipelines are connected in parallel to a total air inlet pipeline, and the total air inlet pipeline is connected to the air inlet of the laser Raman spectroscopic gas analyzer. A connecting valve and a filter are provided on the total air inlet pipeline to filter solid particles or liquids contained in the gas.

[0021] Furthermore, in step (2), the laser Raman spectroscopic gas analyzer is equipped with four switching valves to facilitate air intake and exhaust.

[0022] Furthermore, in step (2), the filter is a filter made of corrosion-resistant PTFE material.

[0023] Furthermore, the response coefficients of each impurity gas component relative to nitrogen are as follows:

[0024] O2 response coefficient R O2 is 0.46, and the response coefficient of HF is R HF The response coefficient of HCl is 0.72. HCl The response coefficient R of POF3 is 0.76. POF3 The response coefficient R of PF5 is 0.32. PF5 is 0.60.

[0025] Preferably, the sample gas in step (4), including but not limited to the final product, can be applied to the mixed gas at each stage in the process.

[0026] Compared with the prior art, the present invention has the following advantages:

[0027] (1) Compared with the external standard curve method, the testing method of the present invention reduces the cost of personnel and the purchase cost of multiple sets of mixed standard gas points.

[0028] (2) The testing method of the present invention can accurately quantify the content of each component in phosphorus pentafluoride.

[0029] (3) The testing method of the present invention adopts the gas Raman spectroscopy testing method to avoid the situation where impurities and main peaks cannot be separated in gas chromatography, and also avoids the situation where the content of diatomic molecules cannot be obtained in gas infrared detection, resulting in inaccurate calculation of the main content. BRIEF DESCRIPTION OF THE DRAWINGS

[0030] Figure 1 This is a gas path connection diagram of the laser Raman spectroscopic gas analyzer of the present application. DETAILED DESCRIPTION

[0031] The technical solution of the present application is further described below through examples.

[0032] The detection conditions of the laser Raman spectroscopic gas analyzer in the following embodiments are: using a helium-neon laser, the excitation light source wavelength is 532nm, and the spectral range is 200-3000cm -1 , the detection frequency is 50ms, the scanning time is 60s (adjustable), the preheating time is 10min, and the pressure is standard atmospheric pressure.

[0033] Embodiment 1

[0034] A method for testing the amount of phosphorus pentafluoride comprises the following steps:

[0035] s1, provide a certain amount of mixed standard gas and sample gas to be tested: the mixed standard gas is a mixture of N2 and O2, a mixture of N2 and HF, a mixture of N2 and HCl, a mixture of N2 and POF3, and a mixture of N2 and PF5. The volume ratio of nitrogen to impurity gas in the mixed standard gas is 9:1.

[0036] s2, use laser Raman spectroscopy gas analyzer to detect the mixed standard gas and the sample gas to be tested. The specific process is as follows: Figure 1As shown, open the purge gas valve 1, the connecting valve 3, and the tail gas exhaust valve 4, so that the circulation pool of the laser Raman spectrometer gas analyzer is filled with nitrogen. At this time, observe the nitrogen signal intensity of the instrument, and wait for 60 seconds until the signal is stable. At the same time, close valves 3 and 4, and then close valve 1 to collect the nitrogen signal intensity. Open the sample air inlet valves 2, 3, and 4. Fill the circulation pool with mixed standard gas or gas to be tested. At this time, observe the signal intensity of the gas to be tested of the instrument, and wait for 60 seconds until the signal is stable. At the same time, close valves 3 and 4, and then close valve 2 to collect the intensity values ​​of each component in the mixed standard gas or gas to be tested.

[0037] S3, open the purge gas valve 1, the connecting valve 3, and the tail gas exhaust valve 4 to clean the circulation pool.

[0038] S4. Obtain the intensity values ​​of five mixed standard gases (each sample is measured three times in parallel) and six sample gases according to the steps of S2 and S3. The results are detailed in Tables 1 and 3.

[0039] Table 1 Intensity values ​​of each component in the mixed standard gas measured by laser Raman spectroscopy gas analyzer

[0040] Sample name <![CDATA[Peak intensity of N2]]> <![CDATA[O2 peak intensity]]> HCl peak intensity HF peak intensity <![CDATA[POF3 peak intensity]]> <![CDATA[PF5 peak intensity]]> 91NO-1 45532 2337 - - - - 91NO-2 44721 2305 - - - - 91NO-3 45691 2330 - - - - 91NC-1 44025 - 3712 - - - 91NC-2 44346 - 3734 - - - 91NC-3 43831 - 3690 - - - 91NF-1 43935 - - 3520 - - 91NF-2 44347 - - 3543 - - 91NF-3 43760 - - 3493 - - 91P3-1 45973 - - - 1634 - 91P3-2 46360 - - - 1641 - 91P3-3 46191 - - - 1645 - 91P5-1 43975 - - - - 2933 91P5-2 43652 - - - - 2912 91P5-3 44328 - - - - 2953

[0041] The response coefficient of each impurity gas in the mixed standard gas in Table 1 relative to nitrogen is calculated according to Formula 1. The results are shown in Table 2.

[0042] R i =ψ 氮 I 杂 / ψ 杂 I 氮 (1)

[0043] Table 2 Response coefficients of various impurity gases to nitrogen

[0044] Component name Relative response coefficient <![CDATA[O2]]> 0.46 HF 0.72 HCl 0.76 <![CDATA[POF3]]> 0.32 <![CDATA[PF5]]> 0.60

[0045] S5. According to the characteristic peak intensity values ​​of each impurity gas in the sample gas to be tested in Table 3, the peak intensity of each impurity gas relative to nitrogen is calculated according to Formula 2. The results are shown in Table 4 for details.

[0046] I Ni =I i / R i (2)

[0047] Table 3 Intensity values ​​of impurity gases in the sample gas to be tested measured by laser Raman spectroscopy gas analyzer

[0048]

[0049] Spend N-1 0.00 21669 1248 5958 113 N-2 29973 3441 328 1409 0 N-3 32145 0 0 4064 0 N-4 35748 0 0 236 357 N-5 26450 0 0 8141 1016 N-6 25093 7576 305 1456 0

[0050] Table 4 Intensity values ​​of each impurity gas relative to nitrogen in the sample gas to be tested

[0051]

[0052] Formula 3 is used to calculate the content of PF5 and impurity gas. The results are shown in Table 5.

[0053] Table 5 PF5 and impurity gas content

[0054] Sample name HCl <![CDATA[PF5]]> <![CDATA[POF3]]> HF <![CDATA[O2]]> unit N-1 0.00 74.44 7.99 17.06 0.51 ％ N-2 81.91 11.90 2.12 4.07 0.00 ％ N-3 88.22 0.00 0.00 11.78 0.00 ％ N-4 97.69 0.00 0.00 0.68 1.62 ％ N-5 72.03 0.00 0.00 23.40 4.57 ％ N-6 67.90 25.97 1.96 4.17 0.00 ％

[0055] Embodiment 2

[0056] The stability of this method was verified using mixed standard gas, which was divided into two groups of gas (N2:O2=90:10 (V ％ :V ％ ), N2: HCl: HF=80:10:10(V ％ :V ％ ), each group of gas was tested three times in parallel. The test was carried out according to the steps of S2 and S3 of Example 1, and the strength values ​​of each component in the two groups of gas are shown in Table 6.

[0057] Table 6 Characteristic intensity values ​​of each gas component in the two groups of gases measured by the laser Raman spectrometer gas analyzer

[0058]

[0059]

[0060] The response coefficient of the impurity gas in the mixed standard gas relative to N2 is obtained by formula 1. The results are shown in Table 7.

[0061] Table 7 Response coefficients of impurity gases in two groups of gases relative to N2

[0062] Sample name <![CDATA[Relative response coefficient of O2]]> HCl relative response coefficient HF relative response coefficient 91NO-1 0.462 - - 91NO-2 0.464 - - 91NO-3 0.459 - - 811NCF-1 - 0.760 0.727 811NCF-2 - 0.757 0.716 811NCF-3 - 0.757 0.736

[0063] As shown in Table 7, in two components, the RSD of the relative response coefficient of O2 is less than 3%, indicating that the experimental results are highly consistent. In multi-components, the relative response coefficients of HCl and HF are both less than 3%, further demonstrating the applicability of this method in multi-component systems.

[0064] Embodiment 3

[0065] Use mixed standard gas N2: HCl: HF: O2 = 90.56: 6.72: 2.12: 0.60 (V ％ :V ％ :V ％ :V ％) was used as an unknown gas to verify the accuracy of the method. Three parallel samples were made and tested according to the steps of S2 and S3 of Example 1. The intensity values ​​of each component in the unknown gas are detailed in Table 8.

[0066] Table 8 Characteristic peak intensity of each component in the mixed standard gas measured by laser Raman spectrometer gas analyzer

[0067] Sample name <![CDATA[Peak intensity of N2]]> HCl peak intensity HF peak intensity <![CDATA[O2 peak intensity]]> Mix 1 44129 2483 745 134 Mix 2 43425 2430 732 135 Mix 3 43192 2446 729 134

[0068] Substituting the data of the above mixed 1 into formula 2, the peak intensity of each component in the mixed standard gas relative to nitrogen is obtained. See Table 9 for details.

[0069] Table 9 Peak intensity of each component in the mixed standard gas relative to nitrogen

[0070]

[0071]

[0072] Substituting the above results into formula 3, we can get the content of each component in the mixed standard gas. For example, the content of nitrogen in mixed 1 is 100%*44129 / (44129+3267+1035+291)=90.57%

[0073] The calculated contents of each component of the mixed gas parallel sample are shown in Table 10.

[0074] Table 10 Content of each component in the mixed standard gas

[0075] Sample name <![CDATA[N2(%)]]> HCl(%) HF(%) <![CDATA[O2(%)]]> Mix 1 90.57 6.71 2.12 0.59 Mix 2 90.60 6.67 2.12 0.61 Mix 3 90.52 6.75 2.12 0.61 average value 90.56 6.71 2.12 0.60 RSD 0.0446％ 0.5961％ 0.0000％ 1.2936％

[0076] It can be seen from Table 10 that the results of three parallel tests are basically consistent with the results of the configured standard gas, indicating that this method is credible. At the same time, RSD < 3%, it is generally considered that the data has good accuracy and repeatability.

[0077] Finally, it should be noted that regarding the detection limit, under a 9:1 (V%:V%) mixed standard gas, the actual intensity is obtained to be the lowest intensity value that is more than 3 times the instrument signal-to-noise ratio. The content of this data is obtained by formulas 2 and 3 as the detection limit.

[0078] Example N2: O2=90:10 (V%:V%),

[0079] Calculated by signal-to-noise ratio, the baseline noise fluctuation is 0.2, 10% / 2330*0.6=25.75ppm, 2330 is the actual intensity, 0.2 is the baseline noise fluctuation, and 0.6 is 3 times the noise value. However, in multi-component mixed gas components, Formula 3 is ultimately required for normalization calculation, and the intensity each time is not an absolute value but a relative value. Under the same baseline noise, the detection limit may be 30ppm or 20ppm or other, and the detection limit cannot be defined as an exact value.

Claims

1. A method for testing the content of phosphorus pentafluoride, characterized in that: The process is as follows: (1) Prepare mixed standard gas and sample gas to be tested; (2) Connect the gas cylinders of the mixed standard gas and the sample gas to be tested to the laser Raman spectrometer gas analyzer respectively; (3) Obtain the characteristic peak intensity value of each component of the mixed standard gas and calculate the response coefficient of each impurity gas relative to nitrogen; based on the obtained response coefficient, calculate the peak intensity of each impurity gas relative to nitrogen, and finally calculate the accurate percentage content of PF5 by normalization method.

2. The method for testing the content of phosphorus pentafluoride according to claim 1, characterized in that: The response coefficient of each impurity gas relative to nitrogen is calculated according to the following formula 1: R i =ψ 氮 I 杂 / ψ 杂 I 氮 (1) R i Represents the relative response coefficient of impurity gas, ψ 氮 and ψ 杂 Represent the volume fractions of nitrogen and impurity gases, I 氮 and I 杂 Represent the peak intensities of nitrogen and impurity gases, respectively.

3. The method for testing the content of phosphorus pentafluoride according to claim 1, characterized in that: The peak intensity of each impurity gas relative to nitrogen is calculated according to the following formula 2: I Ni =I i / R i (2) I Ni Represents the peak intensity when a certain impurity gas in the entire flow cell of the laser Raman spectroscopy gas analyzer is completely converted into nitrogen. i is the actual peak intensity of a certain impurity gas, R i Indicates the relative response coefficient of the impurity gas.

4. The method for testing the content of phosphorus pentafluoride according to claim 1, characterized in that: The exact percentage of PF5 is calculated using the normalization method of the following formula 3: ψ=100%I Ni / (3).

5. The method for testing the content of phosphorus pentafluoride according to claim 1, characterized in that: The mixed standard gas is a mixture of nitrogen and impurity gas, the impurity gas is at least one of O2, HF, HCl, POF3 and PF5, and the impurity gas accounts for 0.5-10% of the volume of the mixed standard gas.

6. The method for testing the content of phosphorus pentafluoride according to claim 1, characterized in that: The laser Raman spectroscopic gas analyzer is equipped with two air inlet pipelines, one for purge gas and the other for mixed standard gas or sample gas. The two air inlet pipelines are connected in parallel to the main air inlet pipeline, and the main air inlet pipeline is connected to the air inlet of the laser Raman spectroscopic gas analyzer. A connecting valve and a filter are provided on the main air inlet pipeline.

7. The method for testing the content of phosphorus pentafluoride according to claim 1, characterized in that: The response coefficients of each impurity gas component relative to nitrogen are as follows: The response coefficient of O2 is R O2 is 0.46, and the response coefficient of HF is R HF The response coefficient of HCl is 0.

72. HCl The response coefficient R of POF3 is 0.

76. POF3 The response coefficient R of PF5 is 0.

32. PF5 is 0.

60.

8. The method for testing the content of phosphorus pentafluoride according to claim 1, characterized in that: The instrument parameters of the laser Raman spectroscopy gas analyzer are as follows: using a helium-neon laser, the excitation light source wavelength is 532nm, and the spectral range is 200~3000cm -1 , the detection frequency is 50ms, the scanning time is 10s~60s, the warm-up time is 10min, and the pressure is standard atmospheric pressure.

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