A detection method for perfluoromethylcyclohexanone

Abstract

A detection method of perfluorohexanone according to the present invention first performs configuration optimization and spectral simulation on C6F 12 O based on the density functional theory (DFT), compares the infrared simulation spectrum with the infrared spectrum obtained from the experiment, analyzes the infrared absorption in the characteristic absorption band, and provides a theoretical basis for the qualitative and quantitative detection of C6F 12 O; then selects the infrared absorption characteristic band that can be used for the quantitative detection of C6F 12 O in the infrared spectrum obtained from the experiment; finally, based on the Lambert-Beer law, a concentration calibration model is established for C6F 12 O, repeated experiments are carried out to perform concentration inversion using the concentration calibration model, and the detection accuracy of the concentration calibration model is evaluated using the inversion results, so as to realize the qualitative and quantitative infrared detection of C6F 12 O in the C6F 12 O / CO2 mixed gas; the determination method is fast and simple, and the theoretical calculation results are in good agreement with the experimental results, and the accurate determination of perfluorohexanone can be realized.

Description

Technical Field

[0001] The present invention belongs to the technical field of perfluoropentanone detection and analysis, and particularly relates to a detection method for perfluoropentanone. Background Art

[0002] SF6 gas has a history of a hundred years. It is an artificial inert gas synthesized by two French chemists, Moissan and Lebeau, in 1900. Currently, SF6 gas is mainly used in the power industry. SF6 gas is used in four types of electrical equipment as insulation and / or arc extinguishing; SF6 circuit breakers and GIS (herein referring to sulfur hexafluoride enclosed gas-insulated switchgear, internationally known as "Gas Insulated Switchgear"), SF6 load switchgear, SF6 gas-insulated transmission pipelines, SF6 transformers, and SF6 gas-insulated substations, with 80% used in high and medium voltage electrical equipment. Due to the extremely high greenhouse effect value and long atmospheric lifetime of SF6, replacing SF6 gas with a new insulating gas has become a new hot topic. Currently, the insulating gases that have received extensive attention mainly include perfluoropentanone, perfluoroisobutyronitrile, perfluoropentanone, etc., and each insulating gas has its own characteristics.

[0003] Perfluoropentanone is a new type of environmentally friendly insulating medium, which is non-toxic, environmentally friendly, and has good dielectric strength. Its potential global warming potential (GWP) is close to 1, and the insulating strength of C6F 12 O gas is 2.7 times that of SF6, and it does not contain bromine and chlorine elements, having the potential to replace SF6. The liquefaction temperature of C6F 12 O at normal pressure is 49°C, making it difficult to directly apply to actual engineering. When C6F 12 O is mixed with a buffer gas, the liquefaction temperature will decrease. The liquefaction temperatures of common buffer gases (CO2, N2) are much lower than that of C6F 12 O, so the liquefaction temperature of the mixed gas is determined by C6F 12 O. The content of C6F 12 O in the C6F 12 O mixed gas has a very important influence on its insulation performance. Accurately and rapidly detecting the content of C6F 12 O in the mixed gas has important engineering significance. Since C6F 12 O is a new type of synthetic substance, infrared spectral data of C6F 12 O cannot be obtained in databases such as NIST Chemistry Web book and HITRAN on the Web. How to detect C6F 12 O, how to evaluate the detection accuracy of C6F 12 O, and how to achieve the detection of C6F 12 O / CO2 mixed gas for C6F12 Qualitative and quantitative infrared detection of O has become a technical problem to be solved. Summary of the Invention

[0004] Aiming at the deficiencies of the prior art, the purpose of the present invention is to provide a method for evaluating the detection accuracy of a concentration calibration model using inversion results, and realizing qualitative and quantitative infrared detection of C6F in a C6F 12 O / CO2 mixed gas. 12 A detection method of perfluoropentanone for qualitative and quantitative infrared detection of C6F in the O / CO2 mixed gas.

[0005] To achieve the above purpose, the present invention provides the following technical solutions: A detection method of perfluoropentanone, comprising the following steps:

[0006] (1) C6F 12 O infrared spectrum simulation: Using the AmsterdamDensity Functional module of the Amsterdam Modeling Suite software platform, based on density functional theory, the B3LYP functional and the 6-31G(d,p) basis set are used to optimize the molecular configuration and calculate the infrared spectrum of C6F 12 O; then use an infrared detection platform to obtain the infrared spectrum with CO2 as the background and the infrared spectrum of the C6F 12 O / C6F mixed gas containing 2000 ppm C6F 12 O. After subtracting the background spectrum, the infrared spectrum of C6F 12 O is obtained experimentally; finally, the calculation results are compared with the experimental results to provide a theoretical basis for the formation of the infrared absorption peak of C6F 12 O;

[0007] (2) C6F 12 O infrared quantitative detection: Selection of the infrared absorption characteristic band for C6F 12 O quantitative detection: When detecting high concentrations, the peak value in the 600-637 cm -1 band is used as the characteristic quantity for fitting; when detecting trace amounts, the peak value in the 1750-1820 cm -1 band is used as the characteristic quantity for fitting;

[0008] (3) Concentration inversion: Based on the Lambert-Beer law, a concentration calibration model is established for C6F 12 O, repeated experiments are carried out, concentration inversion is carried out using the concentration calibration model, and the detection accuracy of the concentration calibration model is evaluated using the inversion results, realizing qualitative and quantitative infrared detection of C6F in the C6F 12 O / CO2 mixed gas; if the relative error of inversion is within 2%, it means that the mixing ratio of the C6F 12 O mixed gas can be effectively detected. 12 O mixed gas for mixing ratio detection.

[0009] Further, in the step (2), for the infrared quantitative detection of C6F 12 O, in the infrared quantitative detection, the optical path length of the gas cell is 0.1 m, the absolute air pressure of the detected gas is 101 kPa, and the scanned waveband range is 400 - 4000 cm -1 , and the spectrometer resolution is selected as 4 cm -1 .

[0010] Further, in the high-concentration detection in the step (2), the standard gas concentrations are determined as follows: the concentrations of C6F 12 O are 1%, 3%, 5%, 7%, and 9% respectively, and the background gas is CO2; correspondingly, in the concentration inversion in the step (3), the standard gas concentrations are determined as follows: the concentrations of C6F 12 O are 2%, 4%, 6%, 8%, and 10% respectively, and the background gas is CO2.

[0011] Further, in the trace detection in the step (2), the standard gas concentrations are determined as follows: the concentrations of C6F 12 O are 100 ppm, 500 ppm, 1000 ppm, 1500 ppm, and 2000 ppm respectively, and the background gas is CO2; correspondingly, in the concentration inversion in the step (3), the standard gas concentrations are determined as follows: the concentrations of C6F 12 O are 200 ppm, 300 ppm, 750 ppm, 1250 ppm, and 2000 ppm respectively, and the background gas is CO2.

[0012] Further, in the infrared quantitative detection of C6F 12 O in the step (2), the indoor temperature is controlled at 24.5 - 25.5 °C.

[0013] Further, before the infrared quantitative detection of C6F 12 O in the step (2), the gas sample to be detected is dried first; the method for drying the gas sample to be detected includes the following steps: 1) First, heat the gas sample to be detected to 100 - 115 °C to obtain a once-heated gas; 2) Send the once-heated gas into a dryer composed of Nafion tubes for primary drying; the flow rate of the once-heated gas inside the Nafion tube is 0.75 - 0.85 L / min, the flow rate of the drying gas outside the Nafion tube is 3.5 - 4.5 L / min, and the temperature of the drying gas is 120 - 125 °C.

[0014] Further, the gas sample to be detected in step (2) is dried once and then dried a second time; the method for the second drying is: the gas dried once is sent into another dryer composed of Nafion tubes for the second drying, and the dried gas sample to be detected is obtained; the flow rate of the gas dried once inside the Nafion tube is 1.5 - 1.8 L / min, the flow rate of the drying gas outside the Nafion tube is 3 - 4 L / min, and the temperature of the drying gas is 105 - 110 °C.

[0015] Further, the gas sample to be detected in step (2) is dried a second time and then dried a third time through a microporous filter; the pore diameter of the microporous filter is 0.1 - 0.2 μm.

[0016] Further, during the concentration inversion in step (3), the optical path length of the gas cell used is 0.1 m, the absolute air pressure of the gas to be detected is 101 kPa, and the scanned band range is 400 - 4000 cm -1 , and the resolution of the spectrometer is selected as 4 cm -1 .

[0017] Further, during the concentration inversion in step (3), the temperature in the control room is controlled at 24.5 - 25.5 °C.

[0018] The detection method of perfluorocyclohexanone of the present invention has the following beneficial effects: First, based on the density functional theory (DFT), the configuration optimization and spectral simulation of C6F 12 O are carried out, the infrared simulation spectrum is compared with the infrared spectrum obtained experimentally, and the infrared absorption in the characteristic absorption band is analyzed, providing a theoretical basis for the qualitative and quantitative detection of C6F 12 O; then the infrared absorption characteristic band available for the quantitative detection of C6F 12 O is selected from the infrared spectrum obtained experimentally; finally, based on the Lambert-Beer law, a concentration calibration model for C6F 12 O is established, repeated experiments are carried out to invert the concentration using the concentration calibration model, and the detection accuracy of the concentration calibration model is evaluated using the inversion results, realizing the qualitative and quantitative infrared detection of C6F 12 O in the C6F 12 O / CO2 mixed gas; the determination method is fast, simple, and the theoretical calculation results are in good agreement with the experimental results, and the accurate determination of perfluorocyclohexanone can be realized.

[0019] The detection method of perfluorocyclohexanone of the present invention analyzes the influence of temperature and O2 on the infrared detection technology of C6F 12 O, and the analysis results show that adding O2 to C6F 12has no effect on the infrared spectrum of O, so it is inferred that O2 has an impact on C6F 12 has no effect on the infrared detection of O; temperature has an impact on C6F 12 has a certain impact on the infrared detection technology of O. In addition to strictly controlling the temperature, it is also necessary to dry the C6F 12 O / CO2 mixed gas to prevent moisture from having an adverse impact on the detection results and detection equipment; for C6F 12 After the first drying treatment of the O / CO2 mixed gas, the moisture content removal rate reaches about 90%; then for C6F 12 After the second drying treatment of the O / CO2 mixed gas, the moisture content removal rate reaches about 95%, and then for C6F 12 After the third drying treatment of the O / CO2 mixed gas, the moisture content removal rate reaches more than 99.5%. Description of the Drawings

[0020] Appendix Figure 1 is the molecular configuration diagram of C6F 12 O;

[0021] Appendix Figure 2 is the infrared spectrum of C6F 12 O obtained by DFT calculation;

[0022] Appendix Figure 3 is the infrared spectrum of the C6F -1 O / CO2 mixed gas with different mixing ratios in the range of 400 - 4000 cm 12 region.

[0023] Appendix Figure 4 is the infrared spectrum of the C6F 12 O / CO2 mixed gas with different mixing ratios in the partial weak peak region. Detailed Implementation Modes

[0024] The following embodiments can help those skilled in the art to more comprehensively understand the present invention, but cannot limit the present invention in any way.

[0025] A detection method for perfluorocyclohexanone of the present invention uses the Amsterdam Density Functional module of the Amsterdam Modeling Suite software platform to optimize the molecular configuration and calculate the infrared spectrum of C6F 12 O based on density functional theory using the B3LYP functional and the 6-31G(d,p) basis set. Then, an infrared detection platform is used to obtain the infrared spectrum with CO2 as the background and the infrared spectrum of the C6F 12 O-containing C6F 12 O / CO2 mixed gas. After subtracting the background spectrum, the experimentally obtained C6F 12O infrared spectrum. Finally, the calculated results are compared with the experimental results to provide a theoretical basis for the formation of the C6F 12 O infrared absorption peak.

[0026] Build the C6F 12 O molecular structure, select the functional and basis set, and perform multiple pre-optimizations on the molecule until the configuration no longer changes. The final optimization results are as Figure 1 shown. Then, use the same functional and basis set to calculate the infrared spectrum of this configuration. The DFT calculation results are as Figure 2 shown by the simulation spectrum broken line. The C6F 12 O infrared spectrum obtained experimentally is as Figure 2 shown by the experimental spectrum broken line. There are no imaginary frequencies in the spectrum after geometric optimization, indicating that the molecular configuration is in the ground state energy state. As Figure 2 shown, based on the above functional, the infrared spectrum of the single molecule C6F 12 O is basically consistent with the C6F 12 O infrared spectrum obtained experimentally in terms of the peak positions and relative peak intensities in the 700 - 750 cm -1 and 950 - 1050 cm -1 bands. In the spectral bands of 1000 - 1400 cm -1 and 1780 - 1800 cm -1 bands, the peak positions and relative peak intensities of the absorption peaks are basically the same; since the C6F 12 O / CO2 mixed gas has CO2 as the background, the absorption in the 650 - 700 cm -1 band reaches saturation, which is the absorption peak of CO2, and the relative absorbance intensity cannot be compared in this band. In the 1000 - 1400 cm -1 band, the vibration frequencies of the absorption peaks are densely distributed, and the peak positions and relative peak intensities of each absorption peak are basically the same.

[0027] Due to the error between the bond lengths and bond angles in the molecular configuration optimized by the functional and those in the actual molecular configuration, the experimental spectrum shows that C6F 12 O has two absorption peaks near the 800 - 85 0 cm -1 band, but there is only one in the infrared simulation diagram of the C6F 12 O molecule. The origin of the infrared absorption here is relatively complex and requires analysis by querying the vibration attribution of the absorption peak corresponding band according to the simulation calculation. The position, intensity, and vibration mode attribution of the absorption peak are related. By using software, the atomic vibration process corresponding to each band during the calculation can be viewed, and then its vibration type can be judged.

[0028] Judging from the main absorption peaks, it is located at 1778 cm -1The absorption peak at [location] is mainly due to the stretching vibration of C (3) =O (7) ; The absorption peak at 1266 cm -1 is caused by the stretching vibration of C (4) -C (5) ; The absorption peak at 1220 cm -1 is attributed to the in-plane bending vibration of C (1) -C (2) -C (6) ; The absorption peak at 1193 cm -1 is caused by the stretching vibration of C (1) -C (2) -C (6) and C (4) -C (3) -C (5) ; The absorption peak at 1186 cm -1 is caused by the out-of-plane bending vibration of C (1) -C (2) -C (6) and the stretching vibration of C (3) -C (4) acting together; The absorption peak at 1179 cm -1 is the combined effect of the in-plane bending vibration of C (1) -C (2) -C (6) and the stretching vibration of C (5) -F (18) ; The absorption peak at 1173 cm -1 is caused by the out-of-plane bending vibration of C (4) -C (3) -C (5) ; The absorption peak at 1161 cm -1 is caused by the asymmetric stretching vibration of C (1) -C (2) -C (6) and the stretching vibration of C (3) -C (4) acting together; The absorption peak at 1141 cm -1 is the stretching vibration of C (5) -F (19) ; The absorption peak at 1137 cm -1 belongs to the twisting vibration of C (1) -C (2) -C (6) ; The absorption peak at 1119 cm -1 belongs to the in-plane rocking vibration of C (1) -C (2) -C (6) ; The absorption peak at 1115 cm -1 is caused by C(1) -C (2) -C (6) in-plane rocking vibration of, C (4) -C (3) -C (5) out-of-plane bending vibration of, and C (2) -F (14) caused by the combined action of stretching vibration; the absorption peak at 1089 cm -1 is due to C (2) -F (14) , C (4) -F (16) caused by the combined action of stretching vibration; the absorption peak at 1064 cm -1 is the stretching vibration of C (4) -F (15) ; the absorption peak at 969 cm -1 is attributed to C (2) -C (3) -C (4) in-plane bending vibration; the absorption peak at 929 cm -1 is caused by the asymmetric stretching vibration of C (2) -C (3) -C (6) ; the absorption peak at 783 cm -1 is caused by the in-plane bending vibration of C (2) -C (3) =O (7) and the symmetric stretching vibration of the CF3 group; and the absorption peaks at 673 cm -1 and 686 cm -1 are both caused by the combined action of the angular vibration of C(2)-C(3)-C(4) and the symmetric angular vibration of the CF3 group, which is the main reason for the fact that there is only one absorption peak in the 700 - 750 cm -1 band during actual detection.

[0029] Simulation of the vibration attribution of C6F 12 O is shown in Table 1 below:

[0030] Table 1

[0031]

[0032] Note:

[0033] Angular vibration ： deformation vibration ， δ ；

[0034] Symmetric angular vibration ：symmetrical deformation vibration, , δ s ；

[0035] Symmetrical stretching vibration ： symmetrical stretching vibration ， ssv ；

[0036] Asymmetric stretching vibration ： asymmetrical stretching vibration ， asv ；

[0037] In-plane bending vibration ： In-plane bending vibration ，β；

[0038] Stretching vibration ： stretching vibration ，v；

[0039] Curl Vibration ： twisting vibration ， τ ；

[0040] In-plane rocking vibration ： rocking vibration ， ρ ；

[0041] Out-of-plane rocking vibration ： wagging vibration ， ω ；

[0042] Out-of-plane bending vibration ： out-of-plane bending vibration ， γ.

[0043] Density functional theory based on C6F 12 The structure of the O molecule was optimized, its infrared spectrum was calculated and compared with the experimental results, and the C6F 12 The vibration assignment of the infrared spectrum of O molecules. The results show that the theoretical calculation results are consistent with the experimental results. 12 O molecule infrared spectrum, obtained C6F 12 The main absorption peak band of O molecules.

[0044] A detection band and characteristic quantity selection scheme for detecting different concentrations of the mixed gas was also carried out.

[0045] In a 40L tank, a C6F 12 O mixed gas with a concentration of 11% was prepared by the partial pressure method, and then a gas mixer was used to prepare C6F 12 O with concentrations of 1%, 3%, 5%, 7%, and 9% respectively. The background gas was selected as CO2, and then infrared detection was carried out. During the detection, the indoor temperature was controlled at 25 °C, the optical path length of the gas cell was 0.1 m, the absolute air pressure of the detected gas was 101 kPa, and the scanned band range was 400 - 4000 cm -1 , and the spectrometer resolution was selected as 4 cm -1 . The average value was taken after 16 scans for each sample detection. After baseline calibration, the infrared spectra of C6F 12 O / CO2 mixed gases with different concentrations are as Figure 3 shown. The 1100 - 1400 cm -1 band is in the concentrated area of carbon skeleton vibration. Figure 3 It can be seen that when the concentration is high, the absorption peak saturation phenomenon is very likely to occur, and this place is not suitable for use as a characteristic peak for high - concentration detection. Similarly, 500 - 550 cm -1 , 650 - 750 cm -1 , 800 - 900 cm -1 , 950 - 1100 cm -1 , 2250 - 2400 cm -1 and 1780 - 1810 cm -1 In these band regions, the absorption spectra at high concentrations are basically saturated and cannot be used as characteristic peaks for detection either. At the same time, when selecting characteristic peaks, the CO2 absorption spectrum region should be avoided.

[0046] Excluding the absorption spectrum saturation region and the CO2 absorption spectrum region, there are many unsaturated infrared absorption peaks of C6F 12 O. The weaker the absorption peak, the higher the upper limit of the detectable concentration. Similarly, the stronger the absorption peak, the lower the lower limit of the detectable concentration. Therefore, it is necessary to select a suitable band according to the detected concentration range. Figure 4 It is the infrared spectra of C6F 12 O / CO2 mixed gases with different concentrations in some weak - peak regions. From Figure 4 it can be seen that the infrared absorption spectra of C6F 12 O / CO2 mixed gases show an increasing trend with the increase of concentration, and the absorption peaks at different concentrations have a good linear relationship. Whether the intensity of the absorption peak will affect the linear relationship of different mixing ratios and whether it will affect the detection error are selected to quantitatively analyze C6F 12 O at different bands.

[0047] The results show that there is a good linear relationship between the absorption peaks at different concentrations, and the fitting effects of various eigenvalue-concentration are all good. The concentration calibration model established using the peak value as the eigenvalue has good reliability. When detecting high concentrations, the fitting effect is higher using the peak value in the 600-637 cm -1 band as the characteristic quantity; when detecting trace amounts, the fitting effect is higher using the peak value in the 1750-1820 cm -1 band as the characteristic quantity; the stability and accuracy of the established concentration calibration model are good. The intensity of the absorption peak affects the concentration detection range. The weaker the absorption peak, the higher the upper limit of the detectable concentration; the stronger the absorption peak, the lower the lower limit of the detectable concentration.

[0048] Example 1 (High-concentration detection)

[0049] A detection method for perfluoromethyl isopropyl ketone, comprising the following steps:

[0050] (1) Infrared spectrum simulation of C6F 12 O: Using the Amsterdam Density Functional module of the Amsterdam Modeling Suite software platform, based on density functional theory, the B3LYP functional and the 6-31G(d,p) basis set are used to optimize the molecular configuration and calculate the infrared spectrum of C6F 12 O; then use an infrared detection platform to obtain the infrared spectrum with CO2 as the background and the infrared spectrum of the C6F 12 O / C6F 12 O / CO2 mixed gas containing 2000 ppm C6F 12 O. After subtracting the background spectrum, the infrared spectrum of C6F 12 O is obtained experimentally; finally, the calculation results are compared with the experimental results to provide a theoretical basis for the formation of the infrared absorption peak of C6F

[0051] (2) Infrared quantitative detection of C6F 12 O: Selection of the infrared absorption characteristic band for the quantitative detection of C6F 12 O: Fitting with the peak value in the 600-637 cm -1 band as the characteristic quantity;

[0052] C6F 12 O, in the infrared quantitative detection, the optical path length of the gas cell is 0.1 m, the absolute pressure of the detected gas is 101 kPa, and the scanned band range is 400-4000 cm -1 , and the spectrometer resolution is selected as 4 cm -1 ; the indoor temperature is controlled at 24.5 °C;

[0053] When detecting high concentrations, the standard gas concentration is determined as: C6F 12The concentrations of C6F5O are 1%, 3%, 5%, 7%, and 9% respectively, and the background gas is CO2;

[0054] (3) Concentration inversion: Based on Lambert-Beer's law, a concentration calibration model is established for C6F5O, and repeated experiments are carried out. The concentration inversion is performed using the concentration calibration model, and the detection accuracy of the concentration calibration model is evaluated using the inversion results to achieve qualitative and quantitative infrared detection of C6F5O in the C6F5O / CO2 mixed gas; if the relative error of the inversion is within 2%, it means that the mixing ratio of the C6F5O mixed gas can be effectively detected; 12 When performing concentration inversion, the optical path length of the gas cell is 0.1 m, the absolute pressure of the detected gas is 101 kPa, and the scanned wavelength range is 400 - 4000 cm-1, and the spectrometer resolution is selected as 4 cm-1; the indoor temperature is controlled at 24.5 °C; 12 The standard gas concentrations are determined as follows: the concentrations of C6F5O are 2%, 4%, 6%, 8%, and 10% respectively, and the background gas is CO2; 12 The results of concentration inversion are shown in Tables 2 - 4 below; 12 Table 2

[0055] When performing concentration inversion, the optical path length of the gas cell is 0.1 m, the absolute pressure of the detected gas is 101 kPa, and the scanned wavelength range is 400 - 4000 cm-1, and the spectrometer resolution is selected as 4 cm-1; the indoor temperature is controlled at 24.5 °C; -1 When performing concentration inversion, the optical path length of the gas cell is 0.1 m, the absolute pressure of the detected gas is 101 kPa, and the scanned wavelength range is 400 - 4000 cm-1, and the spectrometer resolution is selected as 4 cm-1; the indoor temperature is controlled at 24.5 °C; -1 The indoor temperature is controlled at 24.5 °C;

[0056] The standard gas concentrations are determined as follows: the concentrations of C6F5O are 2%, 4%, 6%, 8%, and 10% respectively, and the background gas is CO2; 12 The concentrations of C6F5O are 1%, 3%, 5%, 7%, and 9% respectively, and the background gas is CO2;

[0057] The results of concentration inversion are shown in Tables 2 - 4 below;

[0058] Table 2

[0059]

[0060] Table 3

[0061]

[0062] Table 4

[0063] method (1) (2) (3) (4) average value 0.974 0.829 0.606 0.056 variance 0.338 0.439 0.251 0.354 standard deviation 0.581 0.662 0.501 0.595 product of the absolute value of the average value and the standard deviation 0.566 0.549 0.304 0.033

[0064] Example 2 (trace detection)

[0065] A method for detecting perfluoromethylcyclohexanone, comprising the following steps:

[0066] (1) Infrared spectrum simulation of C6F5O: Using the AmsterdamDensity Functional module of the Amsterdam Modeling Suite software platform, based on density functional theory, the B3LYP functional and the 6-31G(d,p) basis set are used for C6F5O 12 Infrared spectrum simulation of C6F5O: Using the AmsterdamDensity Functional module of the Amsterdam Modeling Suite software platform, based on density functional theory, the B3LYP functional and the 6-31G(d,p) basis set are used for C6F5O 12Optimize the molecular configuration of O and calculate the infrared spectrum; then use the infrared detection platform to obtain the infrared spectrum with CO2 as the background and the infrared spectrum of the C6F 12 O-containing C6F 12 O / CO2 mixed gas infrared spectrum. After subtracting the background spectrum, the experimental C6F 12 O infrared spectrum is obtained; finally, compare the calculation results with the experimental results to provide a theoretical basis for the formation of the C6F 12 O infrared absorption peak;

[0067] (2) Infrared quantitative detection of C6F 12 O: Selection of the infrared absorption characteristic band for the quantitative detection of C6F 12 O: When performing trace detection, use the peak value in the 1750 - 1820 cm -1 band as the characteristic quantity for fitting;

[0068] In the infrared quantitative detection of C6F 12 O, the optical path length of the gas cell is 0.1 m, the absolute pressure of the detected gas is 101 kPa, and the scanned band range is 400 - 4000 cm -1 , and the spectrometer resolution is selected as 4 cm -1 ; control the indoor temperature at 25.5 °C;

[0069] When performing trace detection, the standard concentrations are determined as follows: The concentrations of C6F 12 O are 100 ppm, 500 ppm, 1000 ppm, 1500 ppm, 2000 ppm respectively, and the background gas is CO2;

[0070] (3) Concentration inversion: Based on the Lambert-Beer law, establish a concentration calibration model for C6F 12 O, conduct repeated experiments, use the concentration calibration model for concentration inversion, and evaluate the detection accuracy of the concentration calibration model using the inversion results to achieve qualitative and quantitative infrared detection of C6F 12 O in the C6F 12 O / CO2 mixed gas; if the relative error of inversion is within 2%, it means that the mixing ratio of the C6F 12 O mixed gas can be effectively detected;

[0071] When performing concentration inversion, the optical path length of the gas cell is 0.1 m, the absolute pressure of the detected gas is 101 kPa, and the scanned band range is 400 - 4000 cm -1 , and the spectrometer resolution is selected as 4 cm -1 ; control the indoor temperature at 25.5 °C;

[0072] The standard concentrations are determined as follows: C6F 12The concentrations of O are 200 ppm, 300 ppm, 750 ppm, 1250 ppm, and 2000 ppm respectively, and the background gas is CO2;

[0073] The concentration inversion results are shown in Table 5 below;

[0074] Table 5

[0075]

[0076]

[0077] A detection method for perfluoropentanone of the present invention dries the C6F 12 O / CO2 mixed gas;

[0078] Drying experiment 1: 1) First, heat the gas sample to be detected to 100 °C to obtain the gas after the first heating; 2) Send the gas after the first heating into a dryer composed of Nafion tubes for the first drying; the flow rate of the gas after the first heating inside the Nafion tube is 0.75 L / min, the flow rate of the drying gas outside the Nafion tube is 3.5 L / min, and the temperature of the drying gas is 120 °C; for the C6F 12 The water content removal rate of the O / CO2 mixed gas after the first drying treatment reaches about 90%;

[0079] Drying experiment 2: 1) First, heat the gas sample to be detected to 115 °C to obtain the gas after the first heating; 2) Send the gas after the first heating into a dryer composed of Nafion tubes for the first drying; the flow rate of the gas after the first heating inside the Nafion tube is 0.85 L / min, the flow rate of the drying gas outside the Nafion tube is 4.5 L / min, and the temperature of the drying gas is 125 °C; send the gas after the first drying into another dryer composed of Nafion tubes for the second drying to obtain the dried gas sample to be detected; the flow rate of the gas after the first drying inside the Nafion tube is 1.8 L / min, the flow rate of the drying gas outside the Nafion tube is 4 L / min, and the temperature of the drying gas is 110 °C; for the C6F 12 The water content removal rate of the O / CO2 mixed gas after the second drying treatment reaches about 95%;

[0080] Drying Experiment Three: 1) First, heat the gas sample to be tested to 115°C to obtain the once-heated gas; 2) Feed the once-heated gas into a dryer composed of Nafion tubes for the first drying; the flow rate of the once-heated gas inside the Nafion tube is 0.85 L / min, the flow rate of the drying gas outside the Nafion tube is 4.5 L / min, and the temperature of the drying gas is 125°C; Feed the once-dried gas into another dryer composed of Nafion tubes for the second drying to obtain the dried gas sample to be tested; the flow rate of the once-dried gas inside the Nafion tube is 1.8 L / min, the flow rate of the drying gas outside the Nafion tube is 4 L / min, and the temperature of the drying gas is 110°C; After the gas sample to be tested undergoes the second drying, it is further dried three times through a microporous filter; the pore diameter of the microporous filter is 0.2 μm; For the C6F 12 The O / CO2 mixed gas is dried three times, and the water content removal rate reaches more than 99.5%.

[0081] As can be seen from the above embodiments, a detection method for perfluoromethyl isopropyl ketone provided by the present invention is based on density functional theory (DFT) to optimize the configuration and simulate the spectrum of C6F 12 O, compare the infrared simulation spectrum with the infrared spectrum obtained experimentally, analyze the infrared absorption in the characteristic absorption band, and provide a theoretical basis for the qualitative and quantitative detection of C6F 12 O; Then select the infrared absorption characteristic band available for the quantitative detection of C6F 12 O in the experimentally obtained infrared spectrum; Finally, based on the Lambert-Beer law, establish a concentration calibration model for C6F 12 O, conduct repeated experiments, use the concentration calibration model for concentration inversion, and evaluate the detection accuracy of the concentration calibration model using the inversion results to achieve the qualitative and quantitative infrared detection of C6F 12 O in the C6F 12 O / CO2 mixed gas; The determination method is fast and simple, and the theoretical calculation results are in good agreement with the experimental results, enabling the accurate determination of perfluoromethyl isopropyl ketone; Analyze the influence of temperature and O2 on the infrared detection technology of C6F 12 O. The analysis results show that the addition of O2 has no effect on the infrared spectrum of C6F 12 O. Therefore, it is inferred that O2 has no effect on the infrared detection of C6F 12 O; Temperature has a certain influence on the infrared detection technology of C6F 12 O. In addition to strictly controlling the temperature, the C6F 12 O / CO2 mixed gas also needs to be dried to prevent moisture from having an adverse effect on the detection results and detection equipment; For C6F 12The O / CO2 mixed gas is subjected to a primary drying treatment, and the moisture content removal rate reaches about 90%; then C6F is processed again. 12 The O / CO2 mixed gas is subjected to a secondary drying treatment, and the moisture content removal rate reaches about 95%; then C6F is processed again. 12 The O / CO2 mixed gas is subjected to a tertiary drying treatment, and the moisture content removal rate reaches over 99.5%.

[0082] Although the present invention has been described in detail with general descriptions and specific embodiments above, based on the present invention, some modifications or improvements can be made, which are obvious to those skilled in the art. Therefore, these modifications or improvements made without departing from the spirit of the present invention all fall within the scope of protection required by the present invention.

Claims

1. A detection method for perfluorocyclohexanone, characterized in that, It includes the following steps: (1)C6F 12 O infrared spectrum simulation: Using the Amsterdam Density Functional module of the Amsterdam Modeling Suite software platform, based on density functional theory, the B3LYP functional and the 6-31G(d,p) basis set were used to optimize the molecular configuration and calculate the infrared spectrum of C6F 12 O; then an infrared detection platform was used to obtain the infrared spectrum with CO2 as the background and the infrared spectrum of the C6F 12 O-containing C6F 12 O / CO2 mixed gas. After subtracting the background spectrum, the infrared spectrum of C6F 12 O was obtained experimentally; finally, the calculation results were compared with the experimental results to provide a theoretical basis for the formation of the infrared absorption peak of C6F 12 O; (2)C6F 12 Infrared quantitative detection of C6F 12 Selection of infrared absorption characteristic bands for quantitative detection of C6F: When performing high-concentration detection, the peak value in the band of 600 - 637 cm -1 is used for characteristic quantity fitting; when performing trace detection, the peak value in the band of 1750 - 1820 cm -1 is used for characteristic quantity fitting; (3)Concentration inversion: Based on Lambert-Beer's law, a concentration calibration model is established for C6F 12 O. Repeated experiments are carried out, and the concentration calibration model is used for concentration inversion. The detection accuracy of the concentration calibration model is evaluated using the inversion results, and qualitative and quantitative infrared detection of C6F 12 O in the C6F 12 O / CO2 mixed gas is realized; if the relative errors of the inversion are all within 2%, it means that the mixing ratio of the C6F 12 O mixed gas can be effectively detected.

2. The detection method of perfluoroketone according to claim 1, characterized in that, In the C6F 12 O infrared quantitative detection in step (2), the optical path length of the gas cell is 0.1 m, the absolute pressure of the detected gas is 101 kPa, and the scanned band range is 400~4000 cm -1 , and the spectrometer resolution is selected as 4 cm -1 .

3. The detection method of perfluorocyclohexanone according to claim 1, characterized in that, When performing high-concentration detection in step (2), the standard gas concentrations are determined as follows: the concentrations of C6F 12 O are 1%, 3%, 5%, 7%, and 9% respectively, and the background gas is CO2; correspondingly, when performing concentration inversion in step (3), the standard gas concentrations are determined as follows: C6F 12 O are 2%, 4%, 6%, 8%, and 10% respectively, and the background gas is CO2.

4. The detection method of perfluoroketone according to claim 1, characterized in that, During the micro-detection in step (2), the standard gas concentrations are determined as follows: The concentrations of C6F 12 O are 100 ppm, 500 ppm, 1000 ppm, 1500 ppm, and 2000 ppm respectively, and the background gas is CO2; correspondingly, during the concentration inversion in step (3), the standard gas concentrations are determined as follows: C6F 12 O are 200 ppm, 300 ppm, 750 ppm, 1250 ppm, and 2000 ppm respectively, and the background gas is CO2.

5. The detection method of perfluorohexanone according to claim 1, characterized in that, In the step (2), for the infrared quantitative detection of C6F 12 O, the indoor temperature is controlled at 24.5 to 25.5 °C.

6. The detection method of perfluorhexanone according to claim 1, characterized in that, In step (2), C6F 12 Before the infrared quantitative detection of C6F 12 O, the gas sample to be detected is dried first. The method for drying the gas sample to be detected includes the following steps: 1) First, heat the gas sample to be detected to 100-115°C to obtain the gas heated for the first time; 2) Send the gas heated for the first time into a dryer composed of Nafion tubes for the first drying. The flow rate of the gas heated for the first time inside the Nafion tube is 0.75-0.85 L / min, the flow rate of the drying gas outside the Nafion tube is 3.5-4.5 L / min, and the temperature of the drying gas is 120-125°C.

7. The detection method of perfluorocyclohexanone according to claim 6, characterized in that, In step (2), the gas sample to be detected is dried once and then dried a second time. The method for the second drying is as follows: the gas dried once is sent into another dryer composed of Nafion tubes for the second drying, and thus the dried gas sample to be detected is obtained. The flow rate of the gas dried once inside the Nafion tube is 1.5 - 1.8 L / min, the flow rate of the drying gas outside the Nafion tube is 3 - 4 L / min, and the temperature of the drying gas is 105 - 110 °C.

8. The detection method of perfluoromethylcyclohexanone according to claim 7, characterized in that, In step (2), after the gas sample to be detected is dried a second time, it is dried a third time through a microporous filter. The pore diameter of the microporous filter is 0.1 - 0.2 μm.

9. The detection method of perfluoromethylcyclohexanone according to claim 1, characterized in that, When performing concentration inversion in step (3), the optical path length of the gas cell is 0.1 m, the absolute pressure of the detected gas is 101 kPa, and the scanned wavelength range is 400 - 4000 cm -1 , and the resolution of the spectrometer is selected as 4 cm -1 .

10. The detection method of perfluorocyclohexanone according to claim 1, characterized in that, In step (3), when performing concentration inversion, the temperature in the control room is controlled at 24.5 - 25.5 °C.

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