Composite nanofiber membrane applied to detection of C4F7N gas decomposition component C3F6, preparation method of composite nanofiber membrane and sensing device

Abstract

The invention provides a composite nanofiber membrane applied to detection of a C4F7N gas decomposition component C3F6, a preparation method of the composite nanofiber membrane and a sensing device. The composite nanofiber membrane comprises a polymer nanofiber substrate and a metal organic framework dispersed in the polymer nanofiber substrate, the metal organic framework is MIL-101 (M), and M represents a metal element and comprises at least one of Cr, Cu and lanthanide series metal elements; the surface of the interdigital electrode is coated with the composite nanofiber membrane, and the composite nanofiber membrane serves as a sensing device and is used for detecting C3F6 gas. The sensor disclosed by the embodiment of the invention can generate response within 25s, still has certain sensitivity (which is 3% or above) to 10ppm of C3F6 gas, and meets the requirements on high sensitivity and quick response in detection of a C4F7N gas decomposition product C3F6.

Description

Technical Field

[0001] The present invention relates to the technical field of luminescent materials, in particular to a method for applying C 4 F 7 N gas decomposition components C 3 F 6 A composite nanofiber membrane for detection, a preparation method thereof, and a sensor device. Background Art

[0002] Perfluoroisobutyronitrile (C 4 F 7 N) gas is an innovative insulating gas with excellent insulation performance and environmental protection characteristics. It has been demonstrated and applied in many regions at home and abroad, showing great environmental protection potential. However, during the long-term high-voltage operation of the equipment, discharge or overheating may cause C 4 F 7 N gas decomposes to produce toxic and harmful decomposition products, such as hexafluoropropylene (C 3 F 6 ). These decomposition products will not only reduce the dielectric strength of the insulating medium, but also pose a threat to equipment safety and personnel health. 4 F 7 The decomposition components of N gas, especially toxic and hazardous substances, are crucial for monitoring the operating status of insulation equipment.

[0003] Gas sensors have the advantages of long life, low cost, fast detection speed, small size, and simple system. 4 F 7 The number of sensors for N gas decomposition components is limited, and they generally have problems such as insufficient sensitivity and slow response speed, which makes it difficult to meet the requirements of C 3 F 6 Detection requirements for decomposition products such as chlorinated hydrocarbons.

[0004] Therefore, it is necessary to provide a 3 F 6 A sensor device with high detection sensitivity and fast response speed. Summary of the invention

[0005] The purpose of the present invention is to overcome the existing C 3 F 6 Detection of the sensor's lack of sensitivity and slow response speed provides a method for C 3 F 6 A sensor device with high detection sensitivity and fast response speed.

[0006] To achieve the above object, the first aspect of the present invention provides a method for applying C 4 F 7 N gas decomposition components C3 F 6 The composite nanofiber membrane tested adopts the following technical scheme:

[0007] An application in C 4 F 7 N gas decomposition components C 3 F 6 A composite nanofiber membrane to be tested, wherein the composite nanofiber membrane comprises a polymer nanofiber substrate and a metal organic framework dispersed in the polymer nanofiber substrate, wherein the metal organic framework is MIL-101 (M), wherein M represents a metal element, and the M comprises at least one of Cr, Cu, and lanthanide metal elements;

[0008] The composite nanofiber membrane is coated on the surface of the interdigital electrode and used as a sensor to detect C 3 F 6 gas.

[0009] The composite nanofiber membrane formed by the metal organic framework MIL-101(M) and the polymer nanofiber substrate has a large specific surface area, a regular pore structure, abundant active sites, and a controllable morphology. As a porous material, MIL-101(M) has good adsorption performance, and the high specific surface area and large porosity substrate formed by the interweaving of polymer nanofibers provide MIL-101(M) with more contact sites, enhancing its adsorption capacity for gas molecules; at the same time, it also accelerates the electron exchange rate between MIL-101(M) and gas molecules, which helps C 3 F 6 The penetration and diffusion of gas molecules can significantly improve the sensitivity and response speed of the sensor.

[0010] Preferably, based on the polymer nanofiber substrate, the metal organic framework accounts for 10-40% by mass.

[0011] Preferably, the density of the composite nanofiber membrane is 50-500 mg / cm 3 .

[0012] Preferably, the specific surface area of ​​the composite nanofiber membrane is 5-200m 2 / g.

[0013] Preferably, the ratio of the thickness of the composite nanofiber membrane to the thickness of the interdigital electrode is (2-3):1.

[0014] Preferably, the polymer in the polymer nanofiber substrate includes at least one of polyvinyl alcohol (PEG), polyacrylonitrile (PAN), polyimide (PI), and polymethyl methacrylate (PMMA).

[0015] More preferably, the polymer is polyacrylonitrile.

[0016] Preferably, based on the metal organic framework, the mass percentage of the metal element M is 20-20%.

[0017] Preferably, the metal element M includes Cr and lanthanide metal elements, and the mass ratio of Cr to lanthanide metal elements is 1:(1-2). Cr and lanthanide metal elements work together to significantly improve the metal organic framework's ability to bind C 4 F 7 N and C in gas decomposition components 3 F 6 The lanthanide metal element is preferably at least one of vanadium (La), scandium (Sc), and yttrium (Y).

[0018] The second aspect of the present invention provides the method for applying to C 4 F 7 N gas decomposition components C 3 F 6 The preparation method of the composite nanofiber membrane to be tested comprises the following steps:

[0019] S1 uses electrospinning technology to prepare nanofiber substrates from polymers;

[0020] S2 uses a spray doping method to load the metal organic framework MIL-101 (M) into the nanofiber substrate prepared in step S1 to obtain the composite nanofiber membrane.

[0021] The electrospinning process commonly used in the art can be used in the present invention. Exemplarily, the electrospinning process specifically includes the following steps:

[0022] The polymer raw material is dissolved in a good solvent to form an electrospinning solution with a polymer concentration of 0.1-1.0 g / mL, and electrospinning is performed. The electrospinning parameters are: temperature 20-50°C, voltage 0.1-30 kV, flow rate 0.1-2 cm 3 / h, and the distance is 10-20cm. Electrospinning within the above parameter range can ensure the uniform morphology and dispersion of the prepared polymer fiber filaments, and obtain a polymer fiber matrix with excellent performance.

[0023] Preferably, the specific steps of spray doping in step S2 include: dissolving the metal organic framework MIL-101 (M) in an organic solvent to prepare a 0.01-0.5 g / mL spray liquid, injecting the spray liquid into a spray gun, spraying perpendicularly to the nanofiber substrate, and drying to remove the organic solvent after the spraying is completed. Any organic solvent that can dissolve the metal organic framework commonly used in the art can be used in the present invention.

[0024] In the present invention, the metal organic framework MIL-101 (M) can be prepared by a conventional hydrothermal method in the art, for example, by mixing a hydrated metal salt compound, terephthalic acid (H 2 BDC), sodium acetate (CH 3 COONa) is dissolved in water, reacted at 180-260° C. for 10-20 hours, cooled for crystallization, washed and dried to obtain the metal organic framework MIL-101 (M).

[0025] The third aspect of the present invention provides a method for C 4 F 7 N gas decomposition components C 3 F 6 The sensor device for detection comprises an interdigital electrode and a composite nanofiber membrane coated on the surface of the interdigital electrode, wherein the composite nanofiber membrane is the one applied to C in the first aspect of the present invention. 4 F 7 Composite nanofiber membrane for detection of C3F6, the decomposition component of N2 gas.

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

[0027] The metal organic framework of the present invention is combined with an easily processable high molecular polymer fiber substrate to form a specific structure that is easy to integrate and has excellent processing potential and mechanical properties. In the simulated detection, the sensor of the embodiment of the present invention can generate a response within 25 seconds, meeting the C 4 F 7 N gas decomposition products C 3 F 6 Requirements for high sensitivity and rapid response in detection. BRIEF DESCRIPTION OF THE DRAWINGS

[0028] Figure 1 is a scanning electron microscope image of the composite nanofiber membrane prepared in Example 1;

[0029] Figure 2 The sensor is prepared using the composite nanofiber membrane prepared in Example 1. 3 F 6 Response curves of gas concentration. DETAILED DESCRIPTION

[0030] For better explanation of the purpose, technical scheme and advantage of the present invention, the present invention will be further described below in conjunction with specific embodiment and accompanying drawing, but embodiment does not limit the present invention in any form.Unless otherwise specified, the reagent, method and equipment adopted in the present invention are conventional reagents, methods and equipment in the art.Unless otherwise specified, the reagents and materials used in the present invention are commercially available.

[0031] Example 1

[0032] This embodiment provides a method for C 4 F 7 N gas decomposition components C 3 F 6 The composite nanofiber membrane tested was prepared according to a method comprising the following steps:

[0033] (1) Preparation of metal organic framework MIL-101(Cr)

[0034] 1.1 Reaction solution configuration

[0035] According to the mass percentage of Cr in MIL-101 (Cr), chromium nitrate nonahydrate (Cr(NO 3 ) 3 9H 2 O), terephthalic acid (H 2 BDC) and sodium acetate (CH 3 COONa) was dissolved in deionized water (DI), and the mixture was stirred and ultrasonically dispersed for 3 h to form a homogeneous solution (the concentration of the solute was 10 wt %);

[0036] 1.2 Hydrothermal reaction

[0037] The mixture was further transferred to a reactor containing a polytetrafluoroethylene liner and placed in a 200°C oven for reaction for 15 hours. After the reaction was completed, the polytetrafluoroethylene liner was removed and cooled to room temperature (below 30°C).

[0038] 1.3 Purification

[0039] The reaction mixture was transferred to a centrifuge tube, and N,N-dimethylformamide (DMF) was used as a detergent, and centrifuged at 6000 rpm for 5 minutes, which was repeated three times to remove impurities in the solution, and then washed with deionized water and anhydrous ethanol for 3 times respectively, and placed in a fume hood to dry, and finally placed in a vacuum oven at 60°C to dry for 15 hours to obtain the metal organic framework MIL-101(Cr);

[0040] (2) Preparation of polymer nanofiber substrate

[0041] 2.1 After polyacrylonitrile (weight average molecular weight of 150,000 as measured by gel chromatography) was vacuum dried at 60°C for 24 hours, it was added to solvent N,N-dimethylformamide and stirred at 30°C for 6 hours to obtain an electrospinning solution with a concentration of 0.15 g / mL;

[0042] 2.2 The electrospinning solution was injected into the pinhole syringe of the electrospinning machine. The voltage applied to the needle of the pinhole syringe was 20 kV, the injection rate of the pinhole syringe was 2 mL / h, the horizontal receiving distance between the receiver of the electrospinning machine and the needle of the pinhole syringe was 15 cm, and the electrospinning was performed at 30 ° C for 5 h by the electrospinning machine to form a PAN nanofiber membrane;

[0043] 2.3 The PAN nanofiber membrane was washed with methanol and dried at 60°C for 24 hours to obtain a PAN nanofiber membrane;

[0044] (3) Synthesis of composite nanofiber membranes loaded with metal organic frameworks by spray doping

[0045] 3.1 The metal organic framework MIL-101(Cr) prepared in step (1) was dissolved in an organic solvent, isopropyl alcohol (IPA), and stirred at room temperature (25±5°C) for 1 h. The mixture was then ultrasonically dispersed in an ice bath at 800 W power for 1.5 h to prepare a 0.04 g / mL spray solution.

[0046] 3.2 The spraying liquid was injected into the pneumatic spray gun, and the speed of the drum carrying the PAN nanofiber membrane was set to 165 r / min. The spraying was repeated at a vertical distance of 6 cm and a horizontal range of 12 cm from the surface of the PAN nanofiber membrane to make the MIL-101 (Cr) particles uniformly loaded on the surface of the PAN nanofiber membrane (based on the PAN nanofiber substrate, the mass proportion of the metal organic framework MIL-101 (Cr) was 20%) to obtain a composite membrane;

[0047] 3.3 After spraying, the composite membrane was removed and placed in an oven at 60°C for 12 hours to remove excess solvent and activate the pores of the MIL-101(Cr) particles to obtain a composite nanofiber membrane with a thickness of 120 nm. Other parameters of the membrane are detailed in Table 1.

[0048] Example 2-18

[0049] Provides a range of C 4 F 7 N gas decomposition components C 3 F 6The composite nanofiber membrane tested was prepared according to the method of Example 1. The difference from Example 1 is that the type and amount of reaction raw materials, preparation process parameters, etc. are adjusted to obtain composite nanofiber membranes with different structural parameters. The relevant parameters of the composite nanofiber membrane are detailed in Table 1.

[0050] Table 1

[0051]

[0052] Performance Testing

[0053] 1. Morphological characterization of composite nanofiber membranes

[0054] The morphology of the composite nanofiber membrane was characterized using a scanning electron microscope. Taking Example 1 as an example (other examples are similar), the test results are shown in Figure 1 ,from Figure 1 It can be seen that the fibers in the composite nanofiber membrane are interlaced to form a polyacrylonitrile polymer nanofiber substrate. With the polyacrylonitrile polymer nanofiber substrate as a support, MIL-101(Cr) grows uniformly and stably on the polymer nanofiber substrate.

[0055] 2.C 3 F 6 Gas detection performance test

[0056] The composite nanofiber membranes prepared in the above embodiments are respectively used to coat the surface of the interdigital electrode, and the coating amount is 2:1 according to the ratio of the thickness of the composite nanofiber membrane to the thickness of the interdigital electrode. The interdigital electrode coated with the composite nanofiber membrane is attached to the tin foil of the receiver with tape to obtain a sensor; then the sensor is placed in a resistance detection device to perform gas detection. The specific detection steps are as follows:

[0057] After nitrogen was introduced for 25 min at room temperature (25°C), C 3 F 6 The gas was introduced for 25 seconds each time, and different concentrations of C 3 F 6 After the gas is discharged, nitrogen is introduced again for 25 seconds to recover; the C 3 F 6 The concentration of the gas, Figure 2 The sensor prepared by using the composite nanofiber membrane of Example 1 is C 3 F 6 The response curve of gas concentration is Figure 2 It can be seen that: (1) the sensor of Example 1 increases with C 3F 6 As the gas concentration increases, its response also increases significantly; (2) The sensor of Example 1 responds to 10ppm, 20ppm, 30ppm, 40ppm and 50ppm of C at room temperature. 3 F 6 The response sensitivities of the gases were 3.81%, 8.79%, 12.29%, 16.12% and 18.59% respectively for 10 ppm C 3 F 6 The gas still has a good response; the response sensitivity is calculated according to the following formula:

[0058]

[0059] Among them, R gas is the resistance value after the gas is introduced, in Ω; R 0 It is the reference resistance value before gas is introduced, in Ω.

[0060] (3) The sensor can respond within 25 seconds at room temperature, with high sensitivity, indicating that the composite nanofiber membrane formed by combining the multifunctionality of MIL-101(Cr) with the excellent properties of the polyacrylonitrile nanofiber substrate is applied to the sensor, which has high sensitivity and response speed and meets the requirements for detecting C 3 F 6 Gas or for monitoring C 4 F 7 Requirements for use of N gas sensors.

[0061] The concentration of C was 10 ppm. 3 F 6 Gas, the detection sensitivity of the sensors prepared by the composite nanofiber membranes of the above different embodiments and the existing commercially available sensor (model GTD-5000) were tested, and the results are shown in Table 2.

[0062] Table 2

[0063] Sensitivity (%) Response speed(s) Example 1 3.81 20 Example 2 3.50 21 Example 3 3.40 22 Example 4 3.60 23 Example 5 3.90 18 Example 6 4.10 16 Example 7 3.92 19 Example 8 3.89 20 Example 9 3.41 22 Example 10 3.35 25 Embodiment 11 3.50 22 Example 12 3.45 23 Embodiment 13 3.76 24 Embodiment 14 3.70 23 Embodiment 15 3.80 20 Example 16 3.82 21 Embodiment 17 3.55 24 Embodiment 18 3.75 23 Currently available 2.55 38

[0064] From the above results we can see that:

[0065] The metal organic framework prepared by the present invention is combined with an easily processable high molecular polymer fiber substrate to form a specific structure that is easy to integrate and has excellent processing potential and mechanical properties.

[0066] In the simulation test, the sensor of the embodiment of the present invention can generate a response within 25 seconds to 10ppm C 3 F 6 The gas still has a certain sensitivity (all above 3%), which meets the requirements of C 4 F7 N gas decomposition products C 3 F 6 The requirements for high sensitivity and rapid response in detection are significantly better than the sensitivity of existing commercially available products.

[0067] Finally, it should be noted that the above embodiments are only used to illustrate the technical solution of the present invention rather than to limit the scope of protection of the present invention. Although the present invention has been described in detail with reference to the preferred embodiments, those skilled in the art should understand that the technical solution of the present invention can be modified or replaced by equivalents without departing from the essence and scope of the technical solution of the present invention.

Claims

1. A composite nanofiber membrane used for detecting C3F6, a component of C4F7N gas decomposition, characterized in that: The composite nanofiber membrane polymer nanofiber substrate and a metal organic framework dispersed in the polymer nanofiber substrate, wherein the metal organic framework is MIL-101 (M), wherein M represents a metal element, and the M includes at least one of Cr, Cu, and lanthanide metal elements; The composite nanofiber membrane is coated on the surface of the interdigital electrode and used as a sensor element to detect C3F6 gas.

2. The composite nanofiber membrane for detecting C3F6, a decomposition component of C4F7N gas, according to claim 1, is characterized in that: Based on the polymer nanofiber substrate, the metal organic framework accounts for 10-40% by mass.

3. The composite nanofiber membrane for detecting C4F7N gas decomposition component C3F6 according to claim 1, characterized in that: The density of the composite nanofiber membrane is 50-500 mg / cm 3 .

4. The composite nanofiber membrane for detecting C3F6, a decomposition component of C4F7N gas, according to claim 1, is characterized in that: The specific surface area of ​​the composite nanofiber membrane is 5-200m 2 / g.

5. The composite nanofiber membrane for detecting C3F6, a decomposition component of C4F7N gas, according to claim 1, is characterized in that: The ratio of the thickness of the composite nanofiber membrane to the thickness of the interdigital electrode is (2-3):

1.

6. The composite nanofiber membrane for detecting C3F6, a decomposition component of C4F7N gas, according to claim 1, is characterized in that: The polymer in the polymer nanofiber substrate includes at least one of polyvinyl alcohol, polyacrylonitrile, polyimide, and polymethyl methacrylate.

7. The composite nanofiber membrane for detecting C3F6, a decomposition component of C4F7N gas, according to claim 1, is characterized in that: Based on the metal organic framework, the mass percentage of the metal element M is 10-20%.

8. The method for preparing a composite nanofiber membrane for detecting C4F7N gas decomposition component C3F6 according to any one of claims 1 to 7, characterized in that: The steps include: S1 uses electrospinning technology to prepare nanofiber substrates from polymers; S2 uses a spray doping method to load the metal organic framework MIL-101 (M) into the nanofiber substrate prepared in step S1 to obtain the composite nanofiber membrane.

9. The method for preparing a composite nanofiber membrane for detecting C3F6, a decomposition component of C4F7N gas, according to claim 8, characterized in that: The specific steps of spraying and doping in step S2 include: The metal organic framework MIL-101 (M) is dissolved in an organic solvent to prepare a 0.01-0.5 g / mL spray liquid, and the spray liquid is injected into a spray gun and sprayed perpendicularly to the nanofiber substrate. After the spraying is completed, the organic solvent is removed by drying.

10. A sensor device for detecting C3F6, a decomposition component of C4F7N gas, characterized in that: It comprises an interdigital electrode and a composite nanofiber membrane coated on the surface of the interdigital electrode, wherein the composite nanofiber membrane is the composite nanofiber membrane used for detecting C3F6, a decomposition component of C4F7N gas as described in any one of claims 1 to 7.

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