A composite nanofiber membrane applied to detection of C3F6 decomposed from C4F7N gas, a preparation method thereof and a sensor device

Abstract

This invention provides a composite nanofiber membrane for detecting C3F6, a component of C4F7N gas decomposition, as well as its preparation method and sensor. The composite nanofiber membrane comprises a polymer nanofiber substrate and a metal-organic framework dispersed within the polymer nanofiber substrate. The metal-organic framework is MIL-101(M), where M represents a metal element, including at least one of Cr, Cu, and lanthanides. The composite nanofiber membrane is coated on the surface of an interdigitated electrode, serving as a sensor for detecting C3F6 gas. The sensor of this invention can generate a response within 25 seconds and still exhibits a certain sensitivity (above 3%) to 10 ppm of C3F6 gas, meeting the requirements for high sensitivity and rapid response in the detection of C3F6, a decomposition product of C4F7N gas.

Description

Technical Field

[0001] This invention relates to the field of luminescent materials technology, and in particular to a composite nanofiber membrane for detecting C3F6, a component of C4F7N gas decomposition, as well as its preparation method and sensor device. Background Technology

[0002] Perfluoroisobutyronitrile (C4F7N) gas is an innovative insulating gas with excellent insulation properties and environmental friendliness. It has been demonstrated in numerous regions both domestically and internationally, showcasing significant environmental potential. However, during long-term high-voltage operation of equipment, C4F7N gas may decompose due to discharge or overheating faults, producing toxic and harmful decomposition products such as hexafluoropropylene (C3F6). These decomposition products not only reduce the insulation strength of the insulating medium but also pose a threat to equipment safety and human health. Therefore, detecting the decomposition components of C4F7N gas, especially toxic and harmful substances, is crucial for monitoring the operating status of insulating equipment.

[0003] Gas sensors offer advantages such as long lifespan, low cost, fast detection speed, small size, and simple system design. However, the number of existing sensors for detecting C4F7N gas decomposition components is limited, and they generally suffer from insufficient sensitivity and slow response speed, making it difficult to meet the detection requirements for decomposition products such as C3F6.

[0004] Therefore, there is a need to provide a sensor device with high sensitivity and fast response speed for C3F6 detection. Summary of the Invention

[0005] The purpose of this invention is to overcome the shortcomings of existing C3F6 detection sensors, such as insufficient sensitivity and slow response speed, and to provide a sensor device with high sensitivity and fast response speed for C3F6 detection.

[0006] To achieve the above objectives, a first aspect of the present invention provides a composite nanofiber membrane for detecting C3F6, a component of C4F7N gas decomposition, employing the following technical solution:

[0007] A composite nanofiber membrane for detecting C3F6, a component of C4F7N gas decomposition, comprises a polymer nanofiber substrate and a metal-organic framework dispersed in the polymer nanofiber substrate. The metal-organic framework is MIL-101(M), where M represents a metal element, and M includes at least one of Cr, Cu, and lanthanide metals.

[0008] The composite nanofiber membrane is coated on the surface of the interdigitated electrode and serves as a sensor for detecting C3F6 gas.

[0009] The composite nanofiber membrane formed by the synergistic combination of metal-organic framework MIL-101(M) and polymer nanofiber substrate possesses a large specific surface area, a regular pore structure, abundant active sites, and a controllable morphology. MIL-101(M), as a porous material, exhibits excellent adsorption properties. The high specific surface area and large porosity of the polymer nanofiber substrate provide MIL-101(M) with more contact sites, enhancing its adsorption capacity for gas molecules. Simultaneously, it accelerates the electron exchange rate between MIL-101(M) and gas molecules, facilitating the penetration and diffusion of C3F6 gas molecules, thereby significantly improving the sensor's sensitivity and response speed.

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

[0011] Preferably, the density of the composite nanofiber membrane is 50-500 mg / cm³. 3 .

[0012] Preferably, the specific surface area of ​​the composite nanofiber membrane is 5-200 m². 2 / g.

[0013] Preferably, the ratio of the thickness of the composite nanofiber membrane to the thickness of the interdigitated 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 metal element M is 20-20%.

[0017] Preferably, the metal element M includes Cr and lanthanide elements, with a mass ratio of Cr to lanthanide elements of 1:(1-2). The combined effect of Cr and lanthanide elements can significantly enhance the selective adsorption of C4F7N and C3F6 gas from the gas decomposition components by the metal-organic framework. The lanthanide element is preferably at least one of La, scandium (Sc), and yttrium (Y).

[0018] A second aspect of the present invention provides a method for preparing a composite nanofiber membrane for detecting C3F6, a component of C4F7N gas decomposition, as described in the first aspect of the present invention, comprising the following steps:

[0019] S1 uses an electrospinning process to prepare a nanofiber substrate from polymers;

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

[0021] Commonly used electrospinning processes in this field can be used in this invention. For example, the electrospinning process specifically includes the following steps:

[0022] The polymer raw materials are 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℃, voltage 0.1-30 kV, and flow rate 0.1-2 cm⁻¹. 3 The electrospinning speed is 1 / h, and the distance is 10-20cm. Electrospinning within the above parameter range can ensure that the prepared polymer fiber filaments have uniform morphology and dispersion, resulting in a polymer fiber matrix with excellent performance.

[0023] Preferably, the specific steps of spraying doping in step S2 include: dissolving the metal-organic framework MIL-101(M) in an organic solvent to prepare a spraying solution of 0.01-0.5 g / mL; injecting the spraying solution into a spray gun and spraying it perpendicular to the nanofiber substrate; and drying to remove the organic solvent after spraying. Common organic solvents in the art that can dissolve metal-organic frameworks can be used in this invention.

[0024] In this invention, the metal-organic framework MIL-101(M) can be prepared by conventional hydrothermal methods in the art, for example: dissolving a hydrated metal salt compound, terephthalic acid (H2BDC), and sodium acetate (CH3COONa) in water, reacting at 180-260°C for 10-20 h, and then cooling, crystallizing, washing, and drying to obtain the metal-organic framework MIL-101(M).

[0025] A third aspect of the present invention provides a sensor for detecting C3F6, a component of C4F7N gas decomposition, the sensor comprising interdigitated electrodes and a composite nanofiber membrane covering the surface of the interdigitated electrodes, the composite nanofiber membrane being the composite nanofiber membrane for detecting C3F6, a component of C4F7N gas decomposition, as described in the first aspect of the present invention.

[0026] Compared with the prior art, the beneficial effects of the present invention are:

[0027] The metal-organic framework of this invention, combined with an easily processed polymer fiber substrate, forms a specific structure that is easy to integrate and possesses excellent processing potential and mechanical properties. In simulated detection, the sensor of this embodiment can generate a response within 25 seconds, meeting the requirements for high sensitivity and rapid response in the detection of C3F6, a decomposition product of C4F7N gas. Attached Figure Description

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

[0029] Figure 2 The sensor prepared using the composite nanofiber membrane obtained in Example 1 shows the response curve of C3F6 gas concentration. Detailed Implementation

[0030] To better illustrate the purpose, technical solution, and advantages of this invention, the invention will be further described below with reference to specific embodiments and accompanying drawings. However, the embodiments do not limit the invention in any way. Unless otherwise specified, the reagents, methods, and equipment used in this invention are conventional reagents, methods, and equipment in this technical field. Unless otherwise specified, all reagents and materials used in this invention are commercially available.

[0031] Example 1

[0032] This embodiment provides a composite nanofiber membrane for detecting C3F6, a component of C4F7N gas decomposition, which is prepared by a method including the following steps:

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

[0034] 1.1 Preparation of reaction solution

[0035] According to the mass percentage of Cr in MIL-101(Cr) being 13.5%, chromium nitrate nonahydrate (Cr(NO3)3·9H2O), terephthalic acid (H2BDC), and sodium acetate (CH3COONa) were dissolved in deionized water (DI). The mixture was stirred and ultrasonically dispersed for 3 hours to form a homogeneous solution (the concentration of solute was 10wt%).

[0036] 1.2 Hydrothermal Reaction

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

[0038] 1.3 Purification

[0039] The reaction mixture was transferred to a centrifuge tube and centrifuged at 6000 rpm for 5 minutes using N,N-dimethylformamide (DMF) as a washing agent. This process was repeated three times to remove impurities from the solution. The mixture was then washed three times with deionized water and anhydrous ethanol, respectively. After drying in a fume hood, the mixture was dried in a vacuum oven at 60°C for 15 hours to obtain the metal-organic framework MIL-101(Cr).

[0040] (2) Preparation of polymer nanofiber substrate

[0041] 2.1 Polyacrylonitrile (with a weight-average molecular weight of 150,000 as determined by gel chromatography) was vacuum dried at 60°C for 24 h, then added to the solvent N,N-dimethylformamide and stirred at 30°C for 6 h to obtain an electrospinning solution with a concentration of 0.15 g / mL.

[0042] 2.2 The electrospinning solution was injected into the needle injector of the electrospinning machine. The needle of the needle injector was subjected to a voltage of 20kV and the injection rate of the needle injector was 2mL / h. The horizontal receiving distance between the receiver of the electrospinning machine and the needle of the needle injector was 15cm. Electrospinning was carried out in the electrospinning machine at 30℃ for 5h to form a PAN nanofiber membrane.

[0043] 2.3 The PAN nanofiber membrane is obtained by washing it with methanol and drying it at 60°C for 24 hours.

[0044] (3) Composite nanofiber membranes loaded with metal-organic frameworks were synthesized by spray doping method.

[0045] 3.1 Dissolve the metal-organic framework MIL-101(Cr) prepared in step (1) into the organic solvent isopropanol (IPA), stir at room temperature (25±5℃) for 1 h, and then use an ultrasonic disperser to ultrasonically disperse in an ice bath at 800W power for 1.5 h to prepare a spraying solution of 0.04 g / mL.

[0046] 3.2 Inject the spraying liquid into the pneumatic spray gun, set the speed of the roller carrying the PAN nanofiber membrane to 165 r / min, and spray back and forth within a range of 6 cm vertically and 12 cm laterally from the surface of the PAN nanofiber membrane to uniformly load MIL-101(Cr) particles on the surface of the PAN nanofiber membrane (based on the PAN nanofiber substrate, the mass ratio of metal-organic framework MIL-101(Cr) is 20%), to obtain the composite membrane;

[0047] 3.3 After the spraying is completed, the composite film is 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 film with a thickness of 120 nm. Other parameters of the film are detailed in Table 1.

[0048] Example 2-18

[0049] A series of composite nanofiber membranes for detecting C3F6, a component of C4F7N gas decomposition, are provided. They are prepared according to the method of Example 1, except that the types and amounts of reaction raw materials and preparation process parameters are adjusted to obtain composite nanofiber membranes with different structural parameters. The relevant parameters of the composite nanofiber membranes 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 scanning electron microscopy. Example 1 was used as an example (other examples are similar). The test results are shown below. Figure 1 ,from Figure 1 As can be seen, the fibers in the composite nanofiber membrane are interwoven 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. C3F6 Gas Detection Performance Test

[0056] The composite nanofiber membranes prepared in the above embodiments were respectively coated onto the surface of the interdigital electrodes. The coating amount was based on a 2:1 ratio between the thickness of the composite nanofiber membrane and the thickness of the interdigital electrodes. The interdigital electrodes coated with the composite nanofiber membrane were then attached to the tin foil of the receiver with adhesive tape to obtain the sensor. The sensor was then placed in a resistance detection device for gas detection. The specific detection steps were as follows:

[0057] After passing nitrogen gas for 25 minutes at room temperature (25℃), C3F6 gas with concentrations of 10ppm, 20ppm, 30ppm, 40ppm, and 50ppm was introduced, with each introduction lasting 25 seconds. After introducing different concentrations of C3F6 gas, nitrogen gas was introduced again for 25 seconds to allow for recovery. The concentration of C3F6 gas was detected by measuring the resistance change of a sensor. Figure 2This is the response curve of the sensor prepared using the composite nanofiber membrane of Example 1 to the C3F6 gas concentration. Figure 2 It can be seen that: (1) the response of the sensor in Example 1 increases significantly with the increase of C3F6 gas concentration; (2) the response sensitivity of the sensor in Example 1 to C3F6 gas at 10ppm, 20ppm, 30ppm, 40ppm and 50ppm at room temperature is 3.81%, 8.79%, 12.29%, 16.12% and 18.59% respectively, and it still has a good response to C3F6 gas at 10ppm; the response sensitivity is calculated according to the following formula:

[0058]

[0059] Among them, R gas R0 is the resistance value after gas is introduced, in Ω; R0 is the reference resistance value before gas is introduced, in Ω.

[0060] (3) The sensor can generate a response within 25s at room temperature, which is highly sensitive. This indicates that the composite nanofiber membrane formed by combining the multifunctionality of MIL-101(Cr) with the excellent properties of the polyacrylonitrile nanofiber substrate has high sensitivity and response speed when applied to the sensor, which meets the requirements for the use of sensors for detecting C3F6 gas or monitoring C4F7N gas.

[0061] The detection sensitivity of the sensors prepared by the composite nanofiber membranes of the above different embodiments and the commercially available sensor (model GTD-5000) was tested by introducing C3F6 gas at a concentration of 10 ppm. The results are detailed 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 Example 11 3.50 22 Example 12 3.45 23 Example 13 3.76 24 Example 14 3.70 23 Example 15 3.80 20 Example 16 3.82 21 Example 17 3.55 24 Example 18 3.75 23 Currently available on the market 2.55 38

[0064] The results above show that:

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

[0066] In simulated detection, the sensor of this embodiment of the invention can generate a response within 25 seconds and still has a certain sensitivity (all above 3%) to 10 ppm of C3F6 gas, which meets the requirements of high sensitivity and fast response in the detection of C3F6, the decomposition product of C4F7N gas, and is 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 solutions of the present invention and are not intended to limit the scope of protection of the present invention. Although the present invention has been described in detail with reference to preferred embodiments, those skilled in the art should understand that modifications or equivalent substitutions can be made to the technical solutions of the present invention without departing from the essence and scope of the technical solutions of the present invention.

Claims

1. A sensor device for detection of the decomposition component C3F6 of C4F7N gas, characterized in that The sensor device includes interdigitated electrodes and a composite nanofiber membrane coated on the surface of the interdigitated electrodes. The composite nanofiber membrane includes a polymer nanofiber substrate and a metal-organic framework dispersed in the polymer nanofiber substrate. The metal-organic framework is MIL-101(M), where M represents a metal element, and M includes at least one of Cr, Cu, and lanthanide metal elements. The sensor is used to detect C3F6 gas, and can generate a response within 25 seconds. Its sensitivity to 10 ppm of C3F6 gas is above 3%.

2. The sensor device for detecting C3F6 decomposition component of C4F7N gas according to claim 1, characterized in that, Based on the polymer nanofiber substrate, the metal-organic framework accounts for 10-40% of the total mass.

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

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

5. The sensor device for detecting C3F6 decomposition component of C4F7N gas according to claim 1, characterized by, The ratio of the thickness of the composite nanofiber membrane to the thickness of the interdigitated electrode is (2-3):

1.

6. The sensor device for detecting C3F6 decomposition component of C4F7N gas according to claim 1, characterized by, The polymer in the polymer nanofiber substrate includes at least one of polyvinyl alcohol, polyacrylonitrile, polyimide, and polymethyl methacrylate.

7. The sensor device for detecting C3F6 decomposition component of C4F7N gas according to claim 1, characterized by, Based on the metal-organic framework, the mass percentage of the metal element M is 10-20%.

8. The sensor device for detecting a decomposition component C3F6 of C4F7N gas according to any one of claims 1 to 7, characterized by, The composite nanofiber membrane was prepared by a method comprising the following steps: S1 uses an electrospinning process to prepare a nanofiber substrate from polymers; S2 uses a spray doping method to load the metal-organic framework MIL-101(M) onto the nanofiber substrate prepared in step S1 to obtain the composite nanofiber membrane.

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

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