SF6 harmless degradation method and system based on catalyst

Abstract

The invention discloses an SF6 harmless degradation method and system based on a catalyst. And introducing the proportioned SF6 and protective gas into a reactor loaded with a catalyst for reaction, and breaking the S-F bond of the SF6 to generate SO2. According to the method, SF6 is degraded into SO2, and the problem that the SF6 degradation rate is limited and the degradation effect is poor can be effectively solved by utilizing the characteristic that SO2 is convenient to treat.

Description

Technical Field

[0001] The present invention relates to the technical field of SF6 treatment, and in particular to a catalyst-based SF6 harmless degradation method and system. Background Art

[0002] SF6 is a synthetic industrial gas with excellent electrical insulation and arc extinguishing properties. It is mainly used in electrical insulation, semiconductor processing, metal smelting and other industrial fields. About 80% of SF6 is used in the electrical field. With the advancement of technology and the increase in demand, the use and emission of SF6 are increasing year by year. However, due to its difficulty in degradation, the concentration of SF6 in the atmosphere is getting higher and higher. According to IPCC / TEAP statistics, the concentration of SF6 in the atmosphere was 3.9×10-12L / L in 1998, and it increased at a rate of about 5% per year; the detection data from 2008 to 2013 showed that the average concentration of SF6 was about 6.9×10-12L / L, and it increased at a rate of 0.28×10-12L / L per year. The strong greenhouse effect of SF6 has caused damage to the atmosphere, and the degradation of SF6 has become inevitable.

[0003] In recent years, in order to reduce the damage of SF6 to the atmosphere, there are existing emission reduction methods such as SF6 waste adsorption purification, SF6 replacement gas and SF6 waste degradation and conversion. Among them, discharge degradation technology can achieve high degradation rate and low energy consumption. Low-temperature plasma technology is widely used in waste gas treatment. It has the characteristics of simple structure, low power consumption, high efficiency and easy control. There are related cases in SF6 waste gas treatment with excellent results.

[0004] At present, many scholars have conducted experiments on SF6 waste gas treatment, such as the "Sulfur hexafluoride degradation treatment device based on dielectric barrier discharge" published on June 7, 2019 with the number CN208943805U; the "A method for confirming the efficient and harmless degradation of SF6 waste gas by dielectric barrier discharge" published on June 18, 2021 with the number CN112973399A. These patents mainly dilute the SF6 waste gas and pass it into the dielectric barrier reactor (200) for degradation. At this time, the SF6 degradation rate is limited and the product selectivity is poor.

[0005] The degradation of SF6 is mainly carried out in the form of dielectric barrier discharge. Zhang Xiaoxing and others from Wuhan University used the dielectric barrier discharge method to conduct degradation experiments on SF6. They mainly explored the effects of various factors on SF6 degradation by changing the input voltage, frequency, dielectric type, background gas, and external gas. It was also found that when an appropriate amount of H2O participates in the reaction, the degradation rate and energy efficiency will be improved, and the best effect is achieved when 0.5% water vapor is used as an external gas. However, at this time, the degradation rate of SF6 is limited, the degradation effect is poor, and there are many toxic substances in the product, such as SO2F2, SOF2, etc. This problem needs to be solved. Summary of the invention

[0006] In view of the problem that SF6 is difficult to degrade in the above-mentioned prior art, the present invention is proposed.

[0007] Therefore, the object of the present invention is to provide a catalyst-based SF6 harmless degradation method.

[0008] In order to solve the above technical problems, the present invention provides the following technical solutions: a catalyst-based SF6 harmless degradation method, comprising:

[0009] The mixed SF6 and protective gas are introduced into a reactor loaded with a catalyst for reaction, and SF6 breaks the SF bond to generate SO2.

[0010] As a preferred embodiment of the catalyst-based SF6 harmless degradation method of the present invention, the catalyst is Fe@ZSM-5.

[0011] As a preferred embodiment of the catalyst-based harmless degradation method of SF6 described in the present invention, before the proportioned SF6 and protective gas are introduced into a reactor loaded with a catalyst for reaction, the catalyst Fe@ZSM-5 is prepared, which includes: dissolving Fe(NO3)3·9H2O in water; placing ZSM-5 in the solution; evaporating the solution by water bath to obtain the evaporated catalyst; drying the evaporated catalyst to completely evaporate the water; calcining the catalyst, and the preparation of the catalyst Fe@ZSM-5 is completed.

[0012] As a preferred scheme of the catalyst-based SF6 harmless degradation method of the present invention, the ratio of Fe(NO3)3·9H2O to water is 3.1g of Fe(NO3)3·9H2O per 100ml of water and 70g of ZSM-5 per 100ml of water.

[0013] As a preferred embodiment of the catalyst-based SF6 harmless degradation method of the present invention, the water bath evaporation temperature is 90°C; the drying temperature is 120°C, and the drying time is 12h; the calcination temperature is 550°C, and the calcination time is 4h.

[0014] As a preferred embodiment of the catalyst-based SF6 harmless degradation method of the present invention, the protective gas is Ar.

[0015] As a preferred embodiment of the catalyst-based SF6 harmless degradation method of the present invention, the ratio of Ar to SF6 is 49:1.

[0016] The present invention also proposes a catalyst-based SF6 harmless degradation system. The above-mentioned catalyst-based SF6 harmless degradation method comprises:

[0017] Gas distribution mechanism, used to complete the proportion of SF6 and protective gas;

[0018] A reactor, in which a catalyst is loaded, has an input end and an output end, wherein the input end is connected to a gas distribution mechanism;

[0019] a processing mechanism connected to the output end of the reactor;

[0020] A power supply mechanism, which is used to provide electrical energy to the reactor;

[0021] The gas distribution mechanism delivers the proportioned SF6 and protective gas into the reactor from the input end. SF6 breaks the SF bond under the action of the catalyst and the power supply discharge to generate SO2. The processing mechanism can complete the processing of SO2.

[0022] As a preferred solution of the catalyst-based SF6 harmless degradation system of the present invention, the valve mechanism includes:

[0023] A gas storage tank for storing the SF6 and protective gas separately;

[0024] A gas distributor is connected to the gas storage tank and to the input end of the reactor.

[0025] As a preferred solution of the catalyst-based SF6 harmless degradation system of the present invention, the power supply mechanism includes:

[0026] power supply;

[0027] Transformer, used to adjust the input voltage and power of the power supply;

[0028] A low voltage electrode connected to a power source and disposed inside the reactor;

[0029] A high voltage electrode connected to a power source and disposed outside the reactor;

[0030] The catalyst is filled in the reactor and located between the low-voltage electrode and the high-voltage electrode.

[0031] The beneficial effects of the present invention are as follows: by degrading SF6 into SO2 and utilizing the easy-to-handle property of SO2, the problem of limited SF6 degradation rate and poor degradation effect can be effectively solved. BRIEF DESCRIPTION OF THE DRAWINGS

[0032] In order to more clearly illustrate the technical solutions of the embodiments of the present invention, the following briefly introduces the drawings required for describing the embodiments. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without creative work. Among them:

[0033] Figure 1 This is a data diagram of the hollow tube experimental group in Example 1 of the present invention.

[0034] Figure 2 This is a data chart of the experimental group using ZSM-5 as a catalyst in Example 1 of the present invention.

[0035] Figure 3 This is a data chart of the experimental group using ZSM-5 with 1 wt% Fe content as a catalyst in Example 1 of the present invention.

[0036] Figure 4 This is a data chart of the experimental group using ZSM-5 with 3 wt% Fe content as a catalyst in Example 1 of the present invention.

[0037] Figure 5 This is a data chart of the experimental group using ZSM-5 with 5 wt% Fe content as the catalyst in Example 1 of the present invention.

[0038] Figure 6 This is a comparison chart of 5 groups of experimental data in Example 1 of the present invention.

[0039] Figure 7 This is a diagram of the system structure in Examples 2 and 3 of the present invention.

[0040] Figure 8 This is a detailed diagram of the system in Examples 2 and 3 of the present invention. DETAILED DESCRIPTION

[0041] In order to make the above-mentioned objects, features and advantages of the present invention more obvious and easy to understand, the specific implementation methods of the present invention are described in detail below in conjunction with the accompanying drawings.

[0042] In the following description, many specific details are set forth to facilitate a full understanding of the present invention, but the present invention may also be implemented in other ways different from those described herein, and those skilled in the art may make similar generalizations without violating the connotation of the present invention. Therefore, the present invention is not limited to the specific embodiments disclosed below.

[0043] Secondly, the term "one embodiment" or "embodiment" as used herein refers to a specific feature, structure, or characteristic that may be included in at least one implementation of the present invention. The term "in one embodiment" that appears in different places in this specification does not necessarily refer to the same embodiment, nor is it a separate or selective embodiment that is mutually exclusive with other embodiments.

[0044] Secondly, the present invention is described in detail with reference to the schematic diagram. When describing the embodiments of the present invention in detail, for the sake of convenience, the cross-sectional diagrams showing the device structure will not be partially enlarged according to the general scale, and the schematic diagrams are only examples, which should not limit the scope of protection of the present invention. In addition, in actual production, the three-dimensional dimensions of length, width and depth should be included.

[0045] Example 1

[0046] A catalyst-based harmless degradation method for SF6 is provided, wherein the catalyst Fe@ZSM-5 is firstly prepared;

[0047] Fe@ZSM-5 is added as a catalyst into the reactor 200;

[0048] The mixed SF6 and protective gas are introduced into a reactor 200 loaded with a catalyst for reaction, and SF6 breaks the SF bond to generate SO2.

[0049] Compared with SF6, SO2 is easier to remove and degrade, thus solving the problem that SF6 is difficult to degrade.

[0050] Preferably, the reactor 200 has a power supply structure, which can provide electrical energy to the reactor 200. When SF6 is introduced into the reactor 200, under the dual effects of electrolysis and catalyst Fe@ZSM-5, SF6 breaks the SF bond and reacts with ZSM-5 silicon oxide to generate SO2.

[0051] Furthermore, the power supply structure is a plasma power supply 401. Under the synergistic catalysis of plasma and ZSM-5@Fe, the porous structure of ZSM-5 provides more adsorption sites, increases the residence time of SF6 in the discharge area, and there are micropore discharge and surface discharge, which promotes the full decomposition of SF6, reduces the decomposition activation energy of SF6 under Fe-modified catalysis, and improves the degradation rate of SF6.

[0052] Preferably, SO2 can be treated with alkaline solution. By passing SO2 into the alkaline solution to generate CaSO4 precipitation, SF6 can be harmlessly treated, thus preventing SF6 from being discharged into the atmosphere and causing pollution to the atmosphere and environment.

[0053] Furthermore, the protective gas is Ar, and the ratio of Ar to SF6 is 49:1. After the SF6 degradation tail gas is treated with alkali solution, the main component is Ar. The degradation tail gas is collected after drying and reused to improve the economic efficiency of SF6 degradation.

[0054] When preparing Fe@ZSM-5 as a catalyst, the following steps are included:

[0055] S1. Dissolve Fe(NO3)3·9H2O in water;

[0056] The ratio of Fe(NO3)3·9H2O to water is 3.1 g per 100 ml of water. Fe(NO3)3·9H2O is added to water and stirred to fully dissolve Fe(NO3)3·9H2O in water to obtain a Fe(NO3)3·9H2O solution.

[0057] S2, placing ZSM-5 in the solution;

[0058] When adding ZSM-5, 70 g of ZSM-5 was added for every 100 ml of water in the solution;

[0059] S3, evaporating the solution in a water bath to obtain an evaporated catalyst;

[0060] The temperature of water bath evaporation is 90°C. During evaporation, the water in the solution is evaporated and the ferric nitrate will adhere to the outer surface of ZSM-5. During the process of water bath evaporation, continuous stirring is required to make the ferric nitrate adhere more evenly.

[0061] S4, drying the evaporated catalyst to completely evaporate the water;

[0062] The drying temperature is 120°C and the drying time is 12 hours, which can completely evaporate the moisture.

[0063] S5. calcining the catalyst, and the preparation of the catalyst Fe@ZSM-5 is completed.

[0064] The calcination temperature is 550°C and the calcination time is 4 hours. During the calcination process, the iron nitrate attached to the outer surface of ZSM-5 is reduced to Fe2O3, thereby completing the coating of ZSM-5 with Fe2O3 to prepare the Fe@ZSM-5 catalyst.

[0065] In this example, the impregnation method was used to prepare ZSM-5 catalysts modified with different Fe contents (1, 3, and 5 wt%), wherein the diameter of ZSM-5 was 2.5 mm, and the composition of ZSM-5 was [Na+n(H2O) 16 ][AInSi 96 -nO 192 ]-MFI.

[0066] Firstly, a certain amount of Fe(NO3)3·9H2O was dissolved in 100mlH2O solution to make it fully dissolved, 70gZSM-5 was placed in the solution, evaporated in a 90℃ water bath and stirred continuously to make it evenly attached; the evaporated catalyst was placed in an oven at 120℃ for 12h to completely evaporate the water, and then placed in a tubular furnace at 550℃ for calcination in an air atmosphere for 4h, and the catalyst preparation was completed. Fe@ZSM-5 catalysts with different Fe contents were prepared according to Fe(NO3)3·9H2O solutions with different contents, wherein the Fe contents were 1wt%, 3wt% and 5wt%, respectively. Then, ZSM-5 catalysts modified with different Fe contents (1, 3, 5wt%) were used for SF6 degradation experiments. At the same time, two groups of comparative experiments were set up for comparison. Among the 5 groups of experiments, they were 1. Empty tube experiment; 2. ZSM-5 was added in the tube as a catalyst; 3. ZSM-5 with 1wt% Fe content was added in the tube as a catalyst; 4. ZSM-5 with 3wt% Fe content was added in the tube as a catalyst; 5. ZSM-5 with 5wt% Fe content was added in the tube as a catalyst.

[0067] Specific experimental data refer to Figures 1 to 5 , refer to Figure 6 By comparing the five groups of experiments, we can know that in the experimental group with ZSM-5 containing Fe as the catalyst, the degradation effect of SF6 is significantly better than that of the empty tube experimental group and the experimental group with ZSM-5 not containing Fe as the catalyst.

[0068] Among the experimental groups using ZSM-5 with 1wt%, 3wt%, and 5wt% Fe content as catalyst, when the input power reached 100W, there was no obvious difference in the degradation effect of SF6.

[0069] Example 2

[0070] Reference Figure 7 and Figure 8 This embodiment is different from the first embodiment in that: this embodiment proposes a catalyst-based SF6 harmless degradation system, which is applied to the catalyst-based SF6 harmless degradation method in the above embodiment; it includes a gas distribution mechanism 100, which is used to complete the proportion of SF6 and protective gas, and the gas distribution mechanism 100 can make a good proportion of the protective gas and SF6.

[0071] The system also includes a reactor 200, which is loaded with a catalyst and has an input end 201 and an output end 202. The input end 201 is connected to the gas distribution mechanism 100. When applied to the method in Example 1, Fe@ZSM-5 is loaded as a catalyst inside the reactor 200, and the protective gas and SF6 that are proportioned in the gas distribution mechanism 100 can enter the interior of the reactor 200 through the input end 201.

[0072] The system further comprises a processing mechanism 300 connected to the output end 202 of the reactor 200. The processing mechanism 300 is mainly used to process the degradation products. When applied to the method in Example 1, it is mainly used to decompose SO2.

[0073] The system further includes a power supply mechanism 400 for providing electrical energy to the reactor 200 . When used in the method in Example 1, the power supply mechanism 400 may be a plasma power supply 401 .

[0074] The gas distribution mechanism 100 delivers the proportioned SF6 and protective gas into the reactor 200 from the input end 201. Under the action of the catalyst and the discharge of the power supply 401, the SF6 breaks the SF bond to generate SO2, and the processing mechanism 300 can complete the processing of SO2.

[0075] The rest of the structure is the same as that of Example 1.

[0076] Example 3

[0077] Reference Figure 7 and Figure 8 This embodiment is different from the above embodiments in that: the gas distribution mechanism 100 includes a gas tank 101 for storing SF6 and protective gas separately; a gas distributor 102, which is connected to the gas tank 101 and to the input end 201 of the reactor 200. In this embodiment, the number of gas tanks 101 is two, which are respectively filled with Ar gas and SF6 gas. The gas distributor 102 can mix Ar gas and SF6 gas as needed, and transport them to the inside of the reactor 200 through the input end 201.

[0078] Furthermore, the power supply mechanism 400 includes a power supply 401; a transformer 402 for adjusting the input voltage and power of the power supply 401; a low-voltage electrode 403, connected to the power supply 401 and arranged inside the reactor 200; a high-voltage electrode 404, connected to the power supply 401 and arranged outside the reactor 200; and a catalyst filled inside the reactor 200 and located between the low-voltage electrode 403 and the high-voltage electrode 404.

[0079] As shown in the figure, the entire reactor 200 is a dielectric barrier reactor 200, which is a tubular structure. The low-voltage electrode 403 is located on the inner side of the reactor 200 and is a long columnar structure. The high-voltage electrode 404 is in the shape of a wire mesh and is coated on the outside of the reactor 200. The Fe@ZSM-5 filler 500 is located inside the reactor 200 and wraps the low-voltage electrode 403.

[0080] In this embodiment, the processing mechanism 300 includes an alkali liquid pool 301, a drying box 302 and a collecting tank 303. The alkali liquid pool 301 is loaded with alkali liquid. The output end 202 of the reactor 200 is connected to the discharge pipe. The discharge pipe extends into the alkali liquid in the alkali liquid pool 301 away from the end of the reactor 200. The generated SO2 gas will reach the alkali liquid through the discharge pipe and be decomposed. After the SF6 degradation tail gas is treated with alkali liquid, the main component is Ar. After the degradation tail gas is treated with the drying box 302, it is transported to the inside of the collecting tank 303 for collection. The Ar gas can be reused to improve the economic efficiency of SF6 degradation.

[0081] The rest of the structure is the same as that of Example 2.

[0082] It is important to note that the construction and arrangement of the present application as shown in the various exemplary embodiments are illustrative only. Although only a few embodiments are described in detail in this disclosure, those who refer to this disclosure should readily appreciate that many modifications are possible (e.g., the size, scale, structure, shape and proportion of various elements, and parameter values ​​(e.g., temperature, pressure, etc., mounting arrangements, use of materials, color, changes in orientation, etc.) without materially departing from the novel teachings and advantages of the subject matter described in this application. For example, elements shown as integrally formed may be composed of multiple parts or elements, the positions of elements may be inverted or otherwise changed, and the nature or number or position of discrete elements may be changed or changed. Therefore, all such modifications are intended to be included within the scope of the present invention. The order or sequence of any process or method steps may be changed or reordered according to alternative embodiments. In the claims, any "means plus function" clause is intended to cover the structures described herein that perform the function, and not only structural equivalents but also equivalent structures. Other substitutions, modifications, changes and omissions may be made in the design, operating conditions and arrangement of the exemplary embodiments without departing from the scope of the present invention. Therefore, the present invention is not limited to specific embodiments, but extends to various modifications that still fall within the scope of the appended claims.

[0083] Additionally, in order to provide a concise description of exemplary embodiments, all features of an actual embodiment (ie, those features that are not relevant to the best mode presently contemplated for carrying out the invention or those that are not relevant to implementing the invention) may not be described.

[0084] It will be appreciated that in the development of any actual implementation, as in any engineering or design project, numerous implementation-specific decisions may be made. Such a development effort may be complex and time-consuming, but will be a routine task of design, fabrication, and production for those of ordinary skill having the benefit of this disclosure without undue experimentation.

[0085] It should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention rather than to limit it. 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 solutions of the present invention may be modified or replaced by equivalents without departing from the spirit and scope of the technical solutions of the present invention, which should all be included in the scope of the claims of the present invention.

Claims

1. A catalyst-based SF6 harmless degradation method, characterized in that: include; The mixed SF6 and protective gas are introduced into a reactor (200) loaded with a catalyst for reaction, and SF6 breaks the SF bond to generate SO2.

2. The catalyst-based harmless degradation method of SF6 as claimed in claim 1, characterized in that: The catalyst is Fe@ZSM-5.

3. The SF6 harmless degradation method based on catalyst as claimed in claim 2, characterized in that: Before the proportioned SF6 and protective gas are introduced into the reactor (200) loaded with the catalyst for reaction, the catalyst Fe@ZSM-5 is prepared, which includes: Dissolve Fe(NO3)3·9H2O in water; Placing ZSM-5 in the solution; Evaporating the solution to dryness in a water bath to obtain an evaporated catalyst; Drying the evaporated catalyst to completely evaporate the water; The catalyst is calcined, and the preparation of the catalyst Fe@ZSM-5 is completed.

4. The catalyst-based harmless degradation method of SF6 as claimed in claim 3, characterized in that: The ratio of Fe(NO3)3·9H2O to water is 3.1 g of Fe(NO3)3·9H2O per 100 ml of water, and 70 g of ZSM-5 per 100 ml of water.

5. The catalyst-based harmless degradation method of SF6 as claimed in claim 3 or 4, characterized in that: The temperature of the water bath evaporation is 90°C; The drying temperature is 120°C and the drying time is 12h; The calcination temperature is 550° C. and the calcination time is 4 hours.

6. The catalyst-based harmless degradation method of SF6 as claimed in claim 1, 2, 3 or 4, characterized in that: The protective gas is Ar.

7. The catalyst-based harmless degradation method of SF6 as claimed in claim 6, characterized in that: The ratio of Ar to SF6 is 49:

1.

8. A catalyst-based SF6 harmless degradation system, characterized by: Applicable to the catalyst-based harmless degradation method of SF6 as described in claim 1; These include, A gas distribution mechanism (100), used for completing the proportion of SF6 and protective gas; A reactor (200) with a catalyst loaded therein and having an input end (201) and an output end (202), wherein the input end (201) is connected to a valve mechanism (100); A processing mechanism (300) connected to the output end (202) of the reactor (200); A power supply mechanism (400), which is used to provide electrical energy to the reactor (200); The gas distribution mechanism (100) delivers the proportioned SF6 and protective gas into the reactor (200) from the input end (201). Under the action of the catalyst and the discharge of the power supply (401), the SF6 breaks the SF bond to generate SO2. The processing mechanism (300) can complete the processing of SO2.

9. The catalyst-based SF6 harmless degradation system according to claim 8, characterized in that: The valve mechanism (100) comprises: A gas storage tank (101) for storing the SF6 and the protective gas separately; The gas distributor (102) is connected to the gas storage tank (101) and to the input end (201) of the reactor (200).

10. The catalyst-based SF6 harmless degradation system according to claim 9, characterized in that: The power supply mechanism (400) comprises: Power supply (401); A transformer (402) for adjusting the input voltage and power of the power supply (401); A low voltage electrode (403), connected to the power source (401) and disposed inside the reactor (200); A high voltage electrode (404), connected to the power source (401) and disposed outside the reactor (200); The catalyst is filled inside the reactor (200) and is located between the low-voltage electrode (403) and the high-voltage electrode (404).

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