Catalyst for degrading SF6 as well as preparation method and application of catalyst

Abstract

The invention discloses a catalyst for degrading SF6 as well as a preparation method and application thereof, and relates to the technical field of catalysts. The preparation method of the catalyst for degrading SF6 comprises the following steps: firstly, self-assembling microporous zinc-based MOF (Metal Organic Framework) on the surface of a nano-microsphere template to obtain a carrier with a hierarchical porous structure, removing the template, loading noble metal on the carrier, and finally calcining to obtain the catalyst for degrading SF6. The porous structure of the obtained catalyst not only is beneficial to the loading of noble metal active substances, but also can promote the transmission of photon-generated carriers, so that the piezoelectric-photocatalytic activity to SF6 can be greatly improved. The catalyst prepared by the preparation method provided by the invention can degrade more than 53.8% of SF6 in a piezoelectric electro-catalytic degradation process of 12 hours, has excellent degradation activity and excellent long-range stability, and can still obtain a degradation rate of 96.39% after repeated use and total use time of 96 hours.

Description

Technical Field

[0001] The present invention relates to the technical field of catalysts, and in particular to a catalyst for degrading SF6, and a preparation method and application thereof. Background Art

[0002] SF6 (sulfur hexafluoride) is a widely used gas, playing a vital role in semiconductor manufacturing, power equipment, and weather tracking. However, SF6 is a highly potent greenhouse gas, with a global warming potential (GWP) of 25,000. Its high stability in the atmosphere makes it difficult to degrade naturally, severely impacting the environment. Therefore, the development of efficient and environmentally friendly SF6 degradation technologies has become a hot topic of research. Summary of the Invention

[0003] To address the deficiencies of the prior art, the present invention provides a method for preparing a catalyst for SF6 degradation. First, a microporous zinc-based MOF (metal-organic framework) is formed on the surface of a nanosphere template by self-assembly. The template is then removed to obtain a hierarchical porous carrier, which is then loaded with precious metals and finally calcined. The resulting catalyst carrier contains both microporous and mesoporous or macroporous structures, which not only facilitates the loading of precious metal active substances but also promotes the transport of photogenerated carriers, thereby significantly improving the piezoelectric-photocatalytic degradation activity for SF6.

[0004] Another object of the present invention is to provide a catalyst for degrading SF6.

[0005] Another object of the present invention is to provide an application of a catalyst for degrading SF6.

[0006] Another object of the present invention is to provide a method for piezoelectric photocatalytic degradation of SF6.

[0007] The above-mentioned purpose of the present invention is achieved through the following technical solutions:

[0008] A method for preparing a catalyst for degrading SF6 comprises the following steps:

[0009] S1. Mixing the nanosphere template with a MOF precursor to obtain a precursor having a core-shell structure, wherein the shell layer comprises MOF and the core layer comprises the nanosphere template; the particle size of the nanosphere template is 20 to 80 nm, the MOF precursor comprises a zinc source and an organic ligand, and the pore size of the MOF is 0.3 to 1.2 nm;

[0010] S2. removing the nanosphere template from the precursor obtained in step S1 to obtain a hierarchical porous carrier;

[0011] S3. The graded porous carrier obtained in step S2 is mixed with precious metal ions, adsorbed, and then calcined to obtain a catalyst for degrading SF6; the precious metal includes at least one of Pt, Au, and Ag.

[0012] The preparation method provided by the present invention can prepare a catalyst in which the carrier is a hierarchical porous (containing both micropores and mesopores or macropores) structure of ZnO and the active substance is a noble metal, wherein the noble metal as the active substance can not only be attached to the carrier surface, but also be loaded into the pore structure of the ZnO carrier. Therefore, the catalyst can achieve efficient degradation of SF6 under the action of light-piezoelectric synergy. In the process of catalyst degradation of SF6 by piezoelectric-photocatalysis, ZnO, as a semiconductor, can form photogenerated carriers under light, wherein photogenerated holes can be enriched on the ZnO surface, thereby achieving effective adsorption of SF6, and electrons can tend to be enriched on noble metal nanoparticles, thereby achieving dissociation and activation of SF6; at the same time, ZnO can generate a built-in electric field under the condition of external mechanical action, promote the transport of photogenerated carriers and transfer them to noble metal nanoparticles, further promoting the dissociation and activation of SF6.

[0013] It should be noted that in step S1, the pore size of the MOF formed by the self-assembly of the zinc source and organic ligands is limited, and the nanosphere template uses microspheres with a particle size of 20-80 nm. The selection of these specific sized materials ensures that the resulting product has a specific hierarchical porous structure. The mesoporous or even macroporous structure (>50 nm) synthesized using the microspheres as templates is beneficial for the loading of precious metal active materials, while the micropores provided by the microporous MOF facilitate the transport of photogenerated carriers. Directly synthesizing ZnO with a pore size of 20-80 nm using the zinc source and nanosphere templates as the preparation raw materials does not contain microporous structures in the resulting catalyst, which is not conducive to electron transport and thus reduces catalytic performance. However, directly using a microporous zinc-based MOF with a pore size of 0.3-1.2 nm formed by the zinc source and organic ligands as the catalyst support results in a catalyst with too small pores, and the active material is only loaded on the surface, which is not conducive to dispersion and increased loading.

[0014] It should be noted that if the particle size of the nanosphere template or the pore size of the MOF formed by the zinc source and the organic ligand is too large or too small, the final catalyst structure will be inappropriate, which will lead to a decrease in the loading amount of precious metals or an increase in the difficulty of transporting photogenerated carriers, and finally a decrease in the activity of the catalyst in degrading SF6 through piezoelectric photocatalysis.

[0015] It should be noted that the precious metals selected in the present invention include at least one of Pt, Au, and Ag. The inventors of this application have discovered through extensive experimental research that the aforementioned three precious metals interact well with ZnO, ensuring the catalytic activity of the catalyst. However, other elements such as Pd, Ir, and Rh, although also precious metals, exhibit reduced interaction with the catalyst support of the present invention, resulting in insufficient catalyst activity.

[0016] In a specific embodiment of the present invention, the MOF precursor in step S1 is provided by a MOF precursor solution, and the solvent of the MOF precursor solution includes methanol.

[0017] In a specific embodiment of the present invention, the nanosphere template in step S1 can be any commercially available nanosphere, such as PS (polystyrene) microspheres.

[0018] Preferably, the MOF in step S1 includes at least one of ZIF-8, ZIF-108, MOF-5, and MOF-74(Zn).

[0019] ZIF-8 (pore size ) is composed of 2-methylimidazole and zinc source; ZIF-108 (pore size ) is composed of 2-nitroimidazole and zinc source; MOF-5 (pore size ) is composed of terephthalic acid and a zinc source; MOF-74(Zn) (pore size 1.2nm) is composed of 2,5-dihydroxyterephthalic acid and a zinc source. The pore sizes of the above four MOF materials are all microporous.

[0020] Preferably, the MOF in step S1 is ZIF-8.

[0021] The average pore size of ZIF-8 is The use of ZIF-8 to construct a hierarchical porous carrier in the catalyst can improve the transmission of photogenerated carriers during the piezoelectric photocatalytic degradation of SF6.

[0022] Preferably, the zinc source in step S1 is zinc nitrate, and the mass ratio of the nanosphere template to the zinc source is (0.5-20):5.

[0023] More preferably, the mass ratio of the nanosphere template to the zinc source in step S1 is (1-5):5.

[0024] Preferably, the particle size of the nanosphere template in step S1 is 40 to 60 nm.

[0025] Preferably, the reaction temperature in step S1 is room temperature, and the reaction time is 10 to 14 hours.

[0026] Preferably, step S2 removes the nanosphere template by immersion, wherein the immersion liquid used in the immersion comprises dimethylformamide. More specifically, the immersion temperature is room temperature and the time is 10 to 14 hours. More specifically, the immersion step further comprises the steps of centrifugation, washing, and drying.

[0027] In a specific embodiment of the present invention, the mass ratio of the noble metal ions to the graded porous carrier in step S3 is (0.6-5):100.

[0028] Preferably, in step S3, the mass ratio of the noble metal ions to the graded porous carrier is (0.8-1.2):100.

[0029] In a specific embodiment of the present invention, the noble metal ions in step S3 are provided by a solution containing noble metal ions. The solution containing noble metal ions can be a conventional reagent in the art, or can be obtained by a conventional method in the art. More specifically, the solution containing noble metal ions can be at least one of chloroplatinic acid, chloroauric acid, silver nitrate, and silver acetate.

[0030] Preferably, the noble metal in step S3 is Pt.

[0031] Preferably, the adsorption time in step S3 is 12 to 48 hours.

[0032] Preferably, the calcination temperature in step S3 is 300-500° C. and the calcination time is 2-6 hours.

[0033] The present invention also protects the catalyst for degrading SF6 prepared by the above preparation method.

[0034] Preferably, the mass ratio of the noble metal active material to the ZnO carrier in the catalyst for degrading SF6 is (0.1-10):100.

[0035] The present invention also protects the use of the above catalyst for degrading SF6 in catalyzing the degradation of SF6.

[0036] The present invention also protects a method for piezoelectric photocatalytic degradation of SF6, comprising the following steps:

[0037] The catalyst for degrading SF6 is used to catalytically degrade SF6 under conditions of light irradiation and ultrasound.

[0038] Preferably, the frequency of the ultrasound is 10-100 kHz.

[0039] More preferably, the frequency of the ultrasound is 20 to 100 kHz.

[0040] Preferably, the wavelength of the light is 355-375 nm.

[0041] Preferably, the SF6 is provided by a reaction gas containing SF6, and the concentration of SF6 in the reaction gas is 0.1-10 vol.%. In a specific embodiment of the present invention, the reaction gas further includes a carrier gas and oxygen, and the carrier gas includes nitrogen.

[0042] More preferably, the concentration of SF6 in the SF6-containing reaction gas is 0.1 to 5 vol.%.

[0043] Preferably, the mass volume ratio of the catalyst for degrading SF6 to SF6 is 50 mg: (0.28-14) mL.

[0044] Preferably, the temperature for catalytic degradation of SF6 is room temperature.

[0045] Preferably, the catalytic degradation of SF6 is carried out at a pressure of 0.2 to 5 Pa.

[0046] Compared with the prior art, the present invention has the following beneficial effects:

[0047] The catalyst prepared by the preparation method provided by the present invention can degrade up to 53.8% or more of SF6 during a 12-hour piezoelectric photocatalytic degradation process, and the degradation rate can be increased to 98.22% after the degradation time reaches 24 hours. The degradation activity is excellent. At the same time, the catalyst has excellent long-term stability. After repeated use and a total use time of up to 96 hours, a degradation rate of 96.39% can still be achieved. DETAILED DESCRIPTION

[0048] The present invention will be further described below in conjunction with specific embodiments, but the examples do not limit the present invention in any form. Unless otherwise specified, the raw materials and reagents used in the examples of the present invention are conventionally purchased raw materials and reagents.

[0049] Example 1

[0050] A method for preparing a catalyst for degrading SF6 comprises the following steps:

[0051] S1. 5 g of 50 nm PS microspheres were mixed with 6.75 g of 2-methylimidazole and 8.15 g of zinc nitrate hexahydrate in methanol (mass ratio of PS microspheres to zinc source: 3.07:5). The mixture was reacted at room temperature for 12 h to obtain a core-shell precursor with a shell composed of ZIF-8 and a core composed of PS microspheres.

[0052] S2. The PS microspheres in the precursor were removed by immersion in dimethylformamide for 12 h to obtain a hierarchical porous support;

[0053] S3. The graded porous carrier obtained in step S1 was mixed with chloroplatinic acid in a mass ratio of platinum ions: graded porous carrier = 1:100, adsorbed at room temperature for 24 hours, and calcined at 400°C for 4 hours after adsorption. After calcination, a catalyst for degrading SF6 was obtained.

[0054] Example 2

[0055] A method for preparing a catalyst for degrading SF6, which differs from Example 1 only in that:

[0056] The chloroplatinic acid in step S3 was replaced with an equal amount of chloroauric acid (the mass ratio of gold ions to the hierarchical porous support was 1:100).

[0057] Example 3

[0058] A method for preparing a catalyst for degrading SF6, which differs from Example 1 only in that:

[0059] The chloroplatinic acid in step S3 was replaced with an equal mass of silver nitrate (the mass ratio of silver ions to the hierarchical porous support was 1:100).

[0060] Example 4

[0061] A method for preparing a catalyst for degrading SF6, which differs from Example 1 only in that:

[0062] The particle size of the PS microspheres in step S1 is 80 nm.

[0063] Example 5

[0064] A method for preparing a catalyst for degrading SF6, which differs from Example 1 only in that:

[0065] The particle size of the PS microspheres in step S1 is 30 nm.

[0066] Example 6

[0067] A method for preparing a catalyst for degrading SF6, which differs from Example 1 only in that:

[0068] The adsorption time in step S3 is 12 h.

[0069] Example 7

[0070] A method for preparing a catalyst for degrading SF6, which differs from Example 1 only in that:

[0071] The adsorption time in step S3 is 48 hours.

[0072] Example 8

[0073] A method for preparing a catalyst for degrading SF6, which differs from Example 1 only in that:

[0074] The calcination temperature in step S3 is 300°C.

[0075] Example 9

[0076] A method for preparing a catalyst for degrading SF6, which differs from Example 1 only in that:

[0077] The calcination temperature in step S3 is 500°C.

[0078] Example 10

[0079] A method for preparing a catalyst for degrading SF6, which differs from Example 1 only in that:

[0080] The calcination time in step S3 is 2 hours.

[0081] Example 11

[0082] A method for preparing a catalyst for degrading SF6, which differs from Example 1 only in that:

[0083] The calcination time in step S3 is 6 hours.

[0084] Example 12

[0085] A method for preparing a catalyst for degrading SF6, which differs from Example 1 only in that:

[0086] In step S3, the mass ratio of platinum ions to the graded porous carrier is 0.8:100.

[0087] Example 13

[0088] A method for preparing a catalyst for degrading SF6, which differs from Example 1 only in that:

[0089] In step S3, the mass ratio of platinum ions to the graded porous carrier is 1.2:100.

[0090] Example 14

[0091] A method for preparing a catalyst for degrading SF6, which differs from Example 1 only in that:

[0092] In step S3, the mass ratio of platinum ions to the graded porous carrier is 0.6:100.

[0093] Example 15

[0094] A method for preparing a catalyst for degrading SF6, which differs from Example 1 only in that:

[0095] 2-Methylimidazole (6.75 g) in step S1 was replaced with 2-nitroimidazole (9.30 g), and the resulting MOF was ZIF-108.

[0096] Example 16

[0097] A method for preparing a catalyst for degrading SF6, which differs from Example 1 only in that:

[0098] The 2-methylimidazole (6.75 g) in step S1 was replaced with terephthalic acid (1.72 g), and the resulting MOF was MOF-5.

[0099] Example 17

[0100] A method for preparing a catalyst for degrading SF6, which differs from Example 1 only in that:

[0101] The 2-methylimidazole (6.75 g) in step S1 was replaced with 2,5-dihydroxyterephthalic acid (2.05 g), and the resulting MOF was MOF-74(Zn).

[0102] Comparative Example 1

[0103] A method for preparing a catalyst, which differs from Example 1 only in that:

[0104] The chloroplatinic acid in step S2 was replaced with an equal mass of palladium nitrate.

[0105] Comparative Example 2

[0106] A method for preparing a catalyst, which differs from Example 1 only in that:

[0107] The particle size of the PS microspheres in step S1 is 20 nm.

[0108] Comparative Example 3

[0109] A method for preparing a catalyst, which differs from Example 1 only in that:

[0110] The particle size of the PS microspheres in step S1 is 100 nm.

[0111] Comparative Example 4

[0112] A method for preparing a catalyst, which differs from Example 1 only in that:

[0113] 2-Methylimidazole (6.75 g) in step S1 was replaced with benzimidazole (9.71 g), and the resulting MOF was ZIF-7.

[0114] Performance Testing

[0115] 1. Catalytic efficiency test

[0116] 50 mg of the catalyst obtained in the examples and comparative examples was dispersed in 200 mL of acetonitrile aqueous solution (acetonitrile: water volume ratio = 4:1), 20 mL of methanol was added, and 280 mL of reaction gas was introduced, wherein the reaction gas included 1 vol% SF6 and 20 vol% O2, and the remainder was carrier gas nitrogen; the reaction system was heated at a wavelength of 365 nm and a light intensity of 500 mW / cm 2 The piezoelectric photocatalytic degradation of SF6 was carried out under the conditions of light irradiation and ultrasound at a frequency of 40 kHz. The degradation data of SF6 after 12 hours are shown in Table 1.

[0117] The results are expressed in terms of the degradation rate of SF6. The calculation method for the degradation rate of SF6 is shown in the following formula:

[0118]

[0119] Table 1. Piezoelectric photocatalytic degradation efficiency of SF6 by catalysts obtained in Examples and Comparative Examples

[0120]

[0121]

[0122] As can be seen from Table 1 above, the catalyst prepared by the preparation method provided by the present invention can degrade SF6 by more than 53.8% during the 12-h piezoelectric photocatalytic degradation process, and has excellent degradation activity.

[0123] According to the data of Examples 1 to 3 and Comparative Example 1 in Table 1, it can be seen that when the precious metal is Pt (Example 1), which is preferred in the present invention, the obtained catalyst has a more excellent catalytic effect. However, when the precious metal is Pd (Comparative Example 1), the interaction between the precious metal Pd and the ZnO graded porous support in the present invention decreases, thereby reducing the catalytic activity.

[0124] Examples 1, 4-5, and Comparative Examples 2-3 show that when the nanosphere template particle size is inappropriate (Comparative Examples 2-3), the resulting hierarchical porous support has an inappropriate pore structure, making the transport of photogenerated carriers more difficult, ultimately leading to a decrease in the catalyst's activity in the piezoelectric photocatalytic degradation of SF6. When the nanosphere template particle size is the preferred 40-60 nm (Example 1) of the present invention, the resulting catalyst performs even better.

[0125] According to the data of Examples 1, 6 to 7, it can be seen that increasing the adsorption time in step S2 is beneficial to the adsorption saturation of MOF on the surface of the nanosphere template, thereby improving the degradation effect of the catalyst. However, further increasing the adsorption time (Example 7) on the basis of 24 h (Example 1) may cause the adsorption layer to fall off due to the long adsorption time, so the catalytic effect is slightly reduced.

[0126] According to the data of Examples 1 and 8 to 11, it can be seen that increasing the calcination temperature in step S2 from 300°C to 500°C, and increasing the calcination time from 2h to 6h, will cause the catalytic performance of the catalyst to first increase and then decrease, indicating that when calcined at a certain time and temperature, the structure of the obtained catalyst is more conducive to the catalytic degradation of SF6.

[0127] According to the data of Examples 1, 12 to 14, when the mass ratio of the noble metal ions to the graded porous carrier in step S2 is the preferred ratio of the present invention (0.8 to 1.2): 100 (Examples 1, 12 to 13), the noble metal loading is appropriate and the catalytic performance of the obtained catalyst is better.

[0128] According to the data of Examples 1, 15 to 17, and Comparative Example 4, it can be seen that the type of organic ligand selected in step S1 has a crucial influence on the pore size of MOF. In Comparative Example 4, the MOF constructed by benzimidazole and zinc source is ZIF-7, which has a pore size of only 0.29 nm and cannot fully promote the transport of photogenerated carriers, thereby reducing the catalytic performance.

[0129] 2. Study on the optimal ultrasonic frequency of catalysts in piezoelectric-photocatalytic process

[0130] Next, the optimal ultrasonic frequency of the catalyst during the piezoelectric-photocatalytic process is explored, as shown in Examples 1 to 5.

[0131] Effect example 1.

[0132] 50 mg of the catalyst obtained in Example 1 was dispersed in 200 mL of acetonitrile aqueous solution (acetonitrile: water volume ratio = 4:1), 20 mL of methanol solution was added, and 280 mL of reaction gas was introduced, wherein the reaction gas included 1 vol% SF6 and 20 vol% O2, and the remainder was carrier gas nitrogen. The reaction system was heated at a wavelength of 365 nm and a light intensity of 500 mW / cm 2 The piezoelectric photocatalytic degradation of SF6 was carried out under the conditions of light irradiation and ultrasound at a frequency of 10 kHz. The degradation rate was tested after 12 hours.

[0133] Effect example 2.

[0134] The only difference from Effect Example 1 is that the ultrasonic frequency is 20 kHz.

[0135] Effect example 3.

[0136] The only difference from Effect Example 1 is that the ultrasonic frequency is 40 kHz.

[0137] Effect example 4.

[0138] The only difference from Effect Example 1 is that the ultrasonic frequency is 70 kHz.

[0139] Effect Example 5.

[0140] The only difference from Effect Example 1 is that the ultrasonic frequency is 100 kHz.

[0141] The degradation rate data of the above effect examples are shown in Table 2 below:

[0142] Table 2. Piezoelectric photocatalytic performance of catalysts at different ultrasonic frequencies

[0143]

[0144]

[0145] According to Table 2 above, when the catalyst of the present invention is used to degrade SF6 through a piezoelectric photocatalytic process, the catalyst obtained can exhibit better catalytic activity when the frequency of ultrasound is 10 to 100 kHz, more preferably 20 to 100 kHz.

[0146] 3. Study on the optimal SF6 concentration of the reaction gas in the piezoelectric-photocatalytic process

[0147] Next, the optimal SF6 concentration of the reaction gas in the piezoelectric-photocatalytic process is explored, and the effect examples 6 to 10 are presented.

[0148] Effect Example 6.

[0149] 50 mg of the catalyst obtained in Example 1 was dispersed in 200 mL of acetonitrile aqueous solution (acetonitrile: water volume ratio = 4:1), 20 mL of methanol solution was added, and 280 mL of reaction gas was introduced, wherein the reaction gas included 0.1 vol% SF6 and 20 vol% O2, and the remainder was carrier gas nitrogen. The reaction system was heated at a wavelength of 365 nm and a light intensity of 500 mW / cm 2 The piezoelectric photocatalytic degradation of SF6 was carried out under the conditions of light irradiation and ultrasound at a frequency of 40 kHz. The degradation rate was tested after 12 hours.

[0150] Effect Example 7.

[0151] The only difference from Effect Example 6 is that the concentration of SF6 in the reaction gas is 0.5 vol%.

[0152] Effect Example 8.

[0153] The only difference from Effect Example 6 is that the concentration of SF6 in the reaction gas is 1 vol%.

[0154] Effect Example 9.

[0155] The only difference from Effect Example 6 is that the concentration of SF6 in the reaction gas is 5 vol%.

[0156] Effect Example 10.

[0157] The only difference from Effect Example 6 is that the concentration of SF6 in the reaction gas is 10 vol%.

[0158] The degradation rate data of the above effect examples are shown in Table 3 below:

[0159] Table 3. Piezoelectric photocatalytic performance of catalysts at different SF6 concentrations

[0160] Group Degradation rate Effect Example 6 58.30％ Effect Example 7 68.50％ Effect Example 8 72.20％ Effect Example 9 50.30％ Effect Example 10 22.60％

[0161] According to Table 3 above, when the concentration of SF6 in the reaction gas is 0.1-5 vol.%, which is more preferred in the present invention, and the mass volume ratio of the catalyst to SF6 is 50 mg: (0.28-14) mL (Effective Examples 6-9), which is preferred in the present invention, the catalyst can exert better performance.

[0162] 4. Study on the Stability of Catalysts in Piezoelectric-Photocatalytic Process

[0163] Next, the stability of the catalyst during the piezoelectric-photocatalytic process is investigated, as shown in Examples 11 to 14.

[0164] Effect Example 11.

[0165] 50 mg of the catalyst obtained in Example 1 was dispersed in 200 mL of acetonitrile aqueous solution (acetonitrile: water volume ratio = 4:1), 20 mL of methanol solution was added, and 280 mL of reaction gas was introduced, wherein the reaction gas included 1 vol% SF6 and 20 vol% O2, and the remainder was carrier gas nitrogen. The reaction system was heated at a wavelength of 365 nm and a light intensity of 500 mW / cm 2 The piezoelectric photocatalytic degradation of SF6 was carried out under the conditions of light irradiation and ultrasound at a frequency of 40 kHz. The degradation rate was tested after 24 hours.

[0166] Effect Example 12.

[0167] The only difference from Example 11 is that the catalyst used in Example 11 after 24 hours of reaction is used for catalysis, that is, the catalyst of Example 1 used in Example 11 is taken out, washed and dried, and then redispersed in an acetonitrile aqueous solution, and the remaining steps are carried out according to Example 11.

[0168] Effect Example 13.

[0169] The only difference from Effect Example 11 is that the catalyst used in Effect Example 12 after 24 hours of reaction was used as the catalyst for this Effect Example. Specifically, the catalyst from Example 1 after use in Effect Example 12 was removed, washed, dried, and redispersed in an acetonitrile aqueous solution. The remaining steps were carried out as in Effect Example 11.

[0170] Effect Example 14.

[0171] The only difference from Effect Example 11 is that the catalyst used in Effect Example 13 after 24 hours of reaction was used as the catalyst for this Effect Example. Specifically, the catalyst from Example 1 after use in Effect Example 13 was removed, washed, dried, and redispersed in an acetonitrile aqueous solution. The remaining steps were carried out as in Effect Example 11.

[0172] The degradation rate data of the above effect examples are shown in Table 4 below:

[0173] Table 4. Piezoelectric photocatalytic stability of catalysts

[0174] Group Degradation rate Effect Example 11 98.22％ Effect Example 12 96.38％ Effect Example 13 97.93％ Effect Example 14 96.39％

[0175] According to Table 4 above, it can be seen that the catalyst has good long-term stability, and a degradation rate of 96.39% can still be achieved after repeated use for a total use time of 96 hours.

[0176] 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 the technical solutions of the present invention may be modified or replaced by equivalents without departing from the essence and scope of the technical solutions of the present invention.

Claims

1. A method for preparing a catalyst for degrading SF6, characterized in that: The steps include: S1. Mixing and reacting the nanosphere template with the MOF precursor to obtain a precursor having a core-shell structure, wherein the shell layer comprises MOF and the core layer comprises the nanosphere template; the particle size of the nanosphere template is 20 to 80 nm, the MOF precursor comprises a zinc source and an organic ligand, and the pore size of the MOF is 0.3 to 1.2 nm; S2. removing the nanosphere template from the precursor obtained in step S1 to obtain a hierarchical porous carrier; S3. The graded porous carrier obtained in step S2 is mixed with precious metal ions, adsorbed, and then calcined to obtain a catalyst for degrading SF6; the precious metal includes at least one of Pt, Au, and Ag.

2. The method for preparing a catalyst for degrading SF6 according to claim 1, wherein: The MOF in step S1 includes at least one of ZIF-8, ZIF-108, MOF-5, and MOF-74 (Zn).

3. The method for preparing a catalyst for degrading SF6 according to claim 2, wherein: The MOF in step S1 is ZIF-8.

4. The method for preparing a catalyst for degrading SF6 according to claim 1, wherein: Include at least one of the following (a) to (d): (a) In step S1, the zinc source is zinc nitrate, and the mass ratio of the nanosphere template to the zinc source is (1-5):5; (b) The particle size of the nanosphere template in step S1 is 40 to 60 nm; (c) The reaction temperature in step S1 is room temperature and the reaction time is 10 to 14 hours; (d) Step S2: removing the nanosphere template by immersion, wherein the immersion liquid used in the immersion includes dimethylformamide.

5. The method for preparing a catalyst for degrading SF6 according to claim 1, wherein: The mass ratio of the noble metal ions to the graded porous carrier in step S3 is (0.8-1.2):

100.

6. The method for preparing a catalyst for degrading SF6 according to claim 1, wherein: Include at least one of the following (e) to (g): (e) the noble metal in step S3 is Pt; (f) The adsorption time in step S3 is 12 to 48 hours; (g) The calcination temperature in step S3 is 300-500° C. and the calcination time is 2-6 hours.

7. A catalyst for degrading SF6 prepared by the preparation method according to any one of claims 1 to 6.

8. Use of the catalyst for degrading SF6 according to claim 7 in catalytic degradation of SF6.

9. A method for piezoelectric photocatalytic degradation of SF6, characterized in that: The steps include: The catalyst for degrading SF6 as claimed in claim 7 is used to catalyze the degradation of SF6 under conditions of light and ultrasound.

10. The method for piezoelectric photocatalytic degradation of SF6 according to claim 9, characterized in that: Include at least one of the following (h) to (j): (h) the frequency of the ultrasound is 10 to 100 kHz; (i) the wavelength of the light is 355 to 375 nm; (j) The SF6 is provided by a reaction gas containing SF6, and the concentration of SF6 in the reaction gas containing SF6 is 0.1 to 10 vol.%.

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