Application of bismuth-based compound in photocatalytic degradation of sulfur hexafluoride and method for photocatalytic degradation of sulfur hexafluoride

Abstract

The invention discloses application of a bismuth-based compound in photocatalytic degradation of sulfur hexafluoride and a method for photocatalytic degradation of sulfur hexafluoride. The bismuth-based compound is one of bismuthyl carbonate, bismuth tungstate, a bismuthyl carbonate mixture and a bismuth-based heterojunction. The bismuthyl carbonate mixture is a mixture of one or more of Na2S, Na2SO3, Na2S2O3 and NaI and bismuthyl carbonate; the bismuth-based heterojunction is formed by mixing and stirring a solution containing one or more of sodium sulfide, NaI, Na2SO3 and Na2S2O3 and bismuth subcarbonate, and then drying. The compound disclosed by the invention takes a metal bismuth atom as an active site center, so that adsorption of sulfur hexafluoride can be promoted; and the substance formed in situ and the bulk material form a heterojunction to improve the photodegradation activity. Compared with a traditional technology needing vacuum, the method better conforms to the actual situation and has huge practical potential, materials used in the method do not need to be sintered, the process is simple, and the machining cost is low.

Description

Technical Field

[0001] The invention relates to the field of material technology, and in particular to an application of a bismuth-based compound in photocatalytic degradation of sulfur hexafluoride and a method for photocatalytic degradation of sulfur hexafluoride. Background Art

[0002] In recent years, energy, economy, environment and climate change have become major global issues. Sulfur hexafluoride is one of the world's major greenhouse gases. It has stable chemical properties and can exist in the atmosphere for up to 3,200 years. Its greenhouse effect potential is about 23,900 times that of the same amount of carbon dioxide. At present, sulfur hexafluoride has irreplaceable excellent electrical insulation and arc extinguishing properties, and can be widely used in fields such as high-voltage power transmission, which determines that it is inevitably produced, discharged and leaked in large quantities. Therefore, it is crucial to control the emission of sulfur hexafluoride and find a method for degrading sulfur hexafluoride. At present, there are many methods for treating sulfur hexafluoride, such as adsorption, photodegradation, thermal decomposition, plasma method and catalytic decomposition. Among them, the catalyst of the photocatalytic decomposition method can only degrade sulfur hexafluoride in a vacuum atmosphere, which greatly hinders the practical application of the catalyst for degrading sulfur hexafluoride. Therefore, it is necessary to develop a catalytic material that is energy-saving and environmentally friendly and can degrade sulfur hexafluoride in a general air atmosphere.

[0003] Bismuth-based Aurivillius compounds are non-toxic, non-corrosive, and relatively low-cost narrow-bandgap materials. The ability of Aurivillius compounds to form two-dimensional morphologies is a major advantage in the development of high-surface-area nanophotocatalysts. In particular, those with Aurivillius-type layered structures can generate electrostatic fields within them, which effectively promote the separation and transfer of photogenerated carriers. For example, bismuth oxycarbonate is an outstanding bismuth-based Aurivillius compound semiconductor material. With a unique layered structure and good physicochemical properties, it uses photogenerated charge carriers for photocatalytic reactions and plays the role of a photocatalyst. It has ultraviolet light absorption in the range of 200-400nm and has a wide range of applicability in the field of photocatalysis. In addition, as a commercial reagent, bismuth oxycarbonate is easy to synthesize in large quantities and has low cost, laying the foundation for its adoption on an industrial scale. However, there are currently no reports on its use in catalytic degradation of sulfur hexafluoride.

[0004] The Chinese patent application document with publication number CN117960168A discloses a zinc oxide ultra-thin nanosheet capable of photocatalytically converting sulfur hexafluoride, a preparation method and application. The preparation method comprises: dissolving sodium dodecylbenzene sulfonate in a mixed solvent of water and ethanol, adding zinc chloride, stirring once at 10-18°C, then adding tetramethylammonium hydroxide aqueous solution, a mixed solvent of water and ethanol, stirring twice at 10-18°C, separating the product from the solid and liquid, washing, drying, and calcining in an air atmosphere at 600-800°C. It uses a simple precipitation method to prepare zinc oxide ultra-thin nanosheets with uniform morphology and pure phase. It can be used as a photocatalyst and photocatalytically convert sulfur hexafluoride into 1-fluoropropylene; compared with the traditional photothermal degradation of SF 6 Compared with the previous method, the synthesized zinc oxide ultrathin nanosheets are used as catalysts, which have strong catalytic ability, low energy consumption, and excellent performance. They can simply and stably convert SF 6 Gas, environmentally friendly and sustainable; however, the disclosed catalyst is zinc oxide, which is of a single type, and pure sulfur hexafluoride gas is used. Summary of the invention

[0005] The technical problem to be solved by the present invention is how to photocatalytically degrade low-concentration sulfur hexafluoride.

[0006] The present invention solves the above technical problems through the following technical means:

[0007] A bismuth-based compound is used in photocatalytic degradation of sulfur hexafluoride, wherein the bismuth-based compound is one of bismuth oxycarbonate, bismuth tungstate, bismuth oxycarbonate mixture, and bismuth-based heterojunction; the bismuth oxycarbonate mixture is Na 2 S, Na 2 SO 3 、Na 2 S 2 O 3 , NaI and bismuth carbonate; the bismuth-based heterojunction is composed of sodium sulfide, NaI, Na 2 SO 3 、Na 2 S 2 O 3 The solution of one or more of the above is mixed with bismuth oxycarbonate, stirred and then dried.

[0008] Preferably, a bismuth-based compound is used as a catalyst, water and an organic solvent are used as a mixed solvent, and a sacrificial agent and sulfur hexafluoride are used as raw materials to react to obtain a fluorinated product.

[0009] Preferably, in a bismuth-based heterojunction, Na 2 S, Na 2 SO 3 、Na 2 S 2 O3 , one or more of NaI, and bismuth carbonate are used in an amount ratio of 0.002-0.02 mol: 1 g; in the bismuth carbonate mixture, Na 2 S, Na 2 SO 3 、Na 2 S 2 O 3 The usage ratio of one or more of NaI and bismuth oxycarbonate is 0.5-1mmol:30mg.

[0010] Preferably, the stirring temperature is room temperature and the stirring time is 1 hour.

[0011] The addition of sulfur atoms can form a bismuth sulfide heterojunction to accelerate the reaction.

[0012] The present invention also proposes a method for photocatalytic degradation of sulfur hexafluoride, comprising the following steps: mixing the bismuth-based compound, a mixed solvent and a sacrificial agent, introducing sulfur hexafluoride gas, and reacting under light conditions; wherein the mixed solvent is a mixture of water and an organic solvent.

[0013] Preferably, the volume ratio of water to the organic solvent is 1:4.

[0014] Preferably, the sacrificial agent is a mixture of one or more of triethanolamine, ethanolamine, methanol, benzyl alcohol, and ascorbic acid; the organic solvent is a mixture of one or more of THF (tetrahydrofuran), DMSO (dimethyl sulfoxide), and acetonitrile.

[0015] Preferably, if the sacrificial agent is a liquid, the dosage ratio of the bismuth-based compound and the sacrificial agent is 30-135 mg:0.5 ml, and the volume ratio of the mixed solvent to the sacrificial agent is 5:1; if the sacrificial agent is a solid, the dosage ratio of the bismuth-based compound and the sacrificial agent is 30-135 mg:0.5 mmol, and the dosage ratio of the mixed solvent to the sacrificial agent is 2.5 ml:0.5 mmol.

[0016] Preferably, the sulfur hexafluoride gas is a mixed gas of sulfur hexafluoride and a filling gas, and the volume concentration of sulfur hexafluoride is 3-10 vol.%; the reaction temperature is room temperature, and the light source includes one or both of an LED ultraviolet lamp and a xenon lamp.

[0017] Preferably, the filling gas is a mixture of one or more of argon, air, nitrogen and oxygen.

[0018] Preferably, the light source is a 50W, 365nm LED ultraviolet lamp.

[0019] The advantages of the present invention are:

[0020] (1) The bismuth-based compound catalytic material of the present invention uses bismuth as the active site center and can be selectively loaded with sulfide to form a bismuth sulfide heterojunction. It can be prepared by a simple physical mixing method without sintering, has a simple process, low processing cost, and is suitable for large-scale production.

[0021] (2) The catalytic material of the present invention has excellent degradation ability for sulfur hexafluoride and basically does not produce toxic gases, which is in line with the concept of environmental protection.

[0022] (3) The catalytic material of the present invention can be used with a 50W low-power LED ultraviolet lamp and does not require an external heat source, which is in line with the concept of energy saving.

[0023] (4) The catalytic material of the present invention can degrade sulfur hexafluoride in an air atmosphere, which is different from the previous technology that requires degradation in a vacuum. It is very suitable for the actual situation and has great practical potential. BRIEF DESCRIPTION OF THE DRAWINGS

[0024] Figure 1 The density functional theory (DFT) calculation of the adsorption process of commercial bismuth carbonate in Example 2 of the present invention is shown in Figure 2. 2 O 2 CO 3 -SF 6-ads structure;

[0025] Figure 2 The commercial bismuth carbonate Bi in Example 2 of the present invention 2 O 2 CO 3 -SF 6-ads Charge density difference at the structural interface (isosurface: 0.03 au; purple: electron accumulation region; red: electron depletion region);

[0026] Figure 3 This is the adsorption-desorption isotherm of commercial bismuth carbonate at 298K;

[0027] Figure 4 The Na prepared by 0.5M sodium sulfide solution in Example 1 of the present invention 2 S@Bi 2 O 2 CO 3 Adsorption-desorption isotherms at 298K;

[0028] Figure 5 It is a schematic diagram of the structure of a device for treating sulfur hexafluoride using a bismuth-based compound catalytic material in an embodiment of the present invention;

[0029] Figure 6 The curve showing the change of the photodegradation efficiency of sulfur hexafluoride with the increase of reaction time in Example 2 of the present invention;

[0030] Figure 7 The infrared spectrum of bismuth oxycarbonate during the reaction in air atmosphere in Example 2 of the present invention is changed;

[0031] Figure 8 The Raman spectrum changes of bismuth oxycarbonate during the reaction in air atmosphere in Example 2 of the present invention;

[0032] Fig. 9 The morphological changes of bismuth oxycarbonate under cryo-transmission electron microscopy during the reaction in air atmosphere in Example 2 of the present invention, wherein 0h (a), 1h (b), 17h (c);

[0033] Fig.10 This is the element mapping diagram of bismuth oxycarbonate after reacting in air atmosphere for 1 hour in Example 2 of the present invention;

[0034] Fig.11 The change process of the bismuth element measured by XPS during the reaction in air atmosphere in Example 2 of the present invention;

[0035] Fig.12 is the degradation amount of sulfur hexafluoride under different gas atmospheres in Example 3 of the present invention;

[0036] Fig.13 Na prepared from sodium sulfide solutions of different concentrations in Example 5 of the present invention 2 S@Bi 2 O 2 CO 3 The amount of sulfur hexafluoride degraded by the photocatalyst;

[0037] Fig.14 The Na prepared in Example 1 of the present invention 2 S@Bi 2 O 2 CO 3 、Na 2 S 2 O 3 @Bi 2 O 2 CO 3 and NaI@Bi 2 O 2 CO 3 XRD pattern of

[0038] Fig.15 The liquid obtained by replacing the hydrogen-containing reagent (water, acetonitrile, methanol) in Example 2 of the present invention with the corresponding deuterated reagent and reacting in an air atmosphere for 16 hours 19 F NMR spectrum. DETAILED DESCRIPTION

[0039] In order to make the purpose, technical solution and advantages of the embodiments of the present invention clearer, the technical solution in the embodiments of the present invention will be clearly and completely described in combination with the embodiments of the present invention. Obviously, the described embodiments are part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0040] Unless otherwise specified, the test materials and reagents used in the following examples can be obtained from commercial sources.

[0041] If no specific techniques or conditions are specified in the examples, they can be carried out according to the techniques or conditions described in the literature in the art or according to the product instructions.

[0042] Example 1

[0043] (1) Preparation of bismuth-based heterojunction catalytic materials

[0044] a. Mix 1 g of commercially available bismuth carbonate powder with 20 ml of 0.1M-0.7M (0.1M, 0.3M, 0.4M, 0.5M, 0.6M, 0.7M) sodium sulfide solution, stir in air for 1 h, filter, and vacuum dry to obtain a powdered bismuth-based heterojunction catalyst material named Na 2 S@Bi 2 O 2 CO 3 The XRD pattern of the product prepared using 0.5M sodium sulfide solution is as follows Fig.14 shown.

[0045] b. 1 g of commercially available bismuth carbonate powder was mixed with 20 ml of 0.5 M sodium thiosulfate solution, stirred in air for 1 h, filtered, and vacuum dried to obtain a powdered bismuth-based heterojunction catalyst material named Na 2 S 2 O 3 @Bi 2 O 2 CO 3 , its XRD pattern is as follows Fig.14 shown.

[0046] c. Mix 1 g of commercially available bismuth carbonate powder with 20 ml of 0.5 M sodium iodide solution, stir in air for 1 h, filter, and vacuum dry to obtain a powdered bismuth-based heterojunction catalytic material named NaI@Bi 2 O 2 CO 3 , its XRD pattern is as follows Fig.14 shown.

[0047] (2) Bismuth-based heterojunction catalytic material treatment device for sulfur hexafluoride

[0048] like Figure 5 The figure shows a schematic diagram of the structure of a device for treating sulfur hexafluoride with bismuth-based heterojunction catalytic materials, which includes the following components: 1. a pure sulfur hexafluoride gas cylinder; 2. a gas flow meter; 3. a gas mixer; 4. a quartz reaction tube; 5. an LED lamp; 6. a normal temperature stirring device; 7. a gas chromatograph; A. an air inlet; and B. an outlet for the gas after the reaction.

[0049] Wherein: the air in the air inlet A and the sulfur hexafluoride gas in the pure sulfur hexafluoride gas cylinder 1 pass through the gas flowmeter 2, enter the gas mixer 3 to be mixed, and then are sent to the quartz reaction tube 4. The quartz reaction tube 4 is built with a bismuth-based heterojunction catalytic material, a solvent, and a sacrificial agent. The quartz reaction tube 4 is arranged in front of the LED lamp 5 and is stirred evenly by a normal temperature stirring device 6. The gas treated from the quartz reaction tube 4 is sent to the gas chromatograph 7 and discharged from the B port.

[0050] (3) A method for photocatalytic degradation of sulfur hexafluoride using a bismuth-based heterojunction catalytic material, comprising the following steps:

[0051] A. Configure sulfur hexafluoride waste gas:

[0052] The sulfur hexafluoride waste gas used in the experiment is a mixture of sulfur hexafluoride and air in a simulated configuration. In this embodiment, the concentration of sulfur hexafluoride is controlled by the gas flow meter 2 and the gas mixer 3 to be 3-6 vol.%.

[0053] B. 30 mg of bismuth-based heterojunction catalyst material, 0.5 ml of water, 2 ml of acetonitrile, and 0.5 ml of sacrificial methanol are filled into a quartz reaction tube 4, and sulfur hexafluoride mixed gas is sent into the quartz reaction tube 4 to maintain the pressure at one atmosphere and wait for treatment.

[0054] C. Place the quartz reaction tube 4 under the light of a 365nm 50W LED lamp 5 and treat it at room temperature for 6 hours. The tail gas from the quartz reaction tube 4 is introduced into a GC 7 for analysis and detection.

[0055] Example 2

[0056] The treatment device and treatment method of Example 1 are used, and the difference from Example 1 is that commercial bismuth oxycarbonate material is used instead of the bismuth-based heterojunction catalytic material in Example 1 to degrade sulfur hexafluoride for 17 hours in an air atmosphere, or commercial bismuth oxycarbonate material is used instead of the bismuth-based heterojunction catalytic material in Example 1, and argon is used instead of the air in Example 1 to degrade sulfur hexafluoride for 17 hours in an argon atmosphere. The results are as follows: Figure 6 As shown, the materials before, during and after the reaction were collected and subjected to infrared ( Figure 7 ), Raman Figure 8)、TEM( Fig. 9 )、TEM-mapping( Fig.10 )、XPS( Fig.11 )test.

[0057] from Figure 6 It can be seen that in the argon system, after 6 hours of reaction, the reaction system reached equilibrium and the concentration of sulfur hexafluoride remained almost unchanged. In the air system, the catalyst experienced a process of first activation and then deactivation, in which carbon dioxide began to appear in the system after 2 hours of reaction. After 4 hours of reaction, the amount of sulfur hexafluoride degradation per unit mass of the catalyst was 1.2 mmol / g, and the reaction almost stopped.

[0058] Figure 7 The Fourier transform infrared spectroscopy (FT-IR) test spectrum shows that bismuth carbonate before the reaction is 1390 cm -1 The peak at 1385 cm -1 , which is attributed to Bi 2 S 3 Bi-S bond vibration in; 1153cm -1 The new peak at 506 cm -1 The new peak that appears at corresponds to the vibrational stretching frequency of Bi-O in BiOF.

[0059] Figure 8 In the Raman spectrum of the bismuth carbonate sample after one hour of reaction, the peak at 112 cm -1 The Raman signal at 100 cm-1 shifted to blue in 4 hours. -1 , which corresponds to Bi 2 S 3 Heterojunction signal. The samples with 4 hours and 17 hours of reaction time were at 98 cm -1 The peak at 200-270 cm corresponds to the vibration of Bi-Bi bonds in Bi clusters. -1 The peak corresponds to Bi 2 S 3 The signal at 306cm -1 The peak at corresponds to Bi 2 O 3 , at 430cm -1 The weak broad peak near the E g / B 1g Bi-O pattern generated by the motion of oxygen atoms.

[0060] For sample Bi 2 O 2 CO 3The samples after 1 hour and 17 hours of reaction were observed by cryo-transmission electron microscopy (TEM). The mapping data showed that there were S and F elements on the samples after the reaction, such as Fig.10 As shown in the figure, a black edge is observed around the sample in the high-resolution image of the bismuth carbonate-1h sample, and an amorphous characteristic diffraction pattern can be observed by selecting electron diffraction, which indicates that an amorphous layer of bismuth sulfide is formed on the catalyst surface, such as Fig. 9 As shown in Figure b, the edge of the bismuth carbonate-17h sample can be observed as a black edge and lattice fringes on its outer edge, such as Fig. 9 As shown in Figure c, combined with structural characterization analysis, this is the fluorine atom replacing CO on the sample surface. 3 2- Entering into the crystal lattice and reconstructed.

[0061] Fig.11 XPS characterization was used to further explore the changes in catalyst elements during the reaction. In the overall spectrum, peaks of C1s, O 1s and Bi 4f can be detected in all four samples. Compared with the samples before the reaction, the catalyst after the reaction can detect the new appearance of fluorine on the sample; the sulfur signal was not detected, which may be due to the low content of sulfur and low response. Through the analysis of Bi 4f, it can be obtained that bismuth sulfide and bismuth oxyfluoride are generated on the surface of the sample after the reaction.

[0062] Example 3

[0063] The treatment device and treatment method of Example 1 are used, and the difference from Example 1 is that 30 mg of commercial bismuth oxycarbonate material is used to replace the bismuth-based heterojunction catalytic material therein, and argon, nitrogen, oxygen, a mixed gas of argon and air with a volume fraction of 0.8% of air, and a mixed gas of oxygen and argon with a volume fraction of 2% of oxygen are used to replace the air in Example 1. Sulfur hexafluoride is degraded under different gas atmospheres (including argon, air, nitrogen, oxygen, a mixed gas of argon and air with a volume fraction of 0.8% of air, and a mixed gas of oxygen and argon with a volume fraction of 2%). The results are as follows: Fig.12 shown.

[0064] from Fig.12It can be seen that: when there is an initial volume concentration of 3% to 6% sulfur hexafluoride, when the filling gas is an inert gas argon, the reaction is not disturbed by the filling gas, and the sulfur hexafluoride that can be degraded is 0.43mmol / g; when the filling gas is air or about 0.8% air / argon Ar mixed gas, relatively more sulfur hexafluoride can be degraded (1.2mmol / g, 0.96mmol / g respectively); when the reaction filling gas is nitrogen, it has similar degradation activity compared with argon (0.43mmol / g); when the reaction filling gas is oxygen, the reaction degradation activity is 0.94mmol / g and the reaction system produces a large amount of carbon dioxide, indicating that oxygen can promote the degradation of sulfur hexafluoride, but it will also decompose the catalyst. Bismuth oxycarbonate can be used as a catalyst to degrade sulfur hexafluoride gas in an air atmosphere.

[0065] Example 4

[0066] The treatment device and treatment method of Example 1 are used, and the difference from Example 1 is that in step B, commercial bismuth oxycarbonate is used to replace the bismuth-based heterojunction catalytic material therein, and different sulfide additives are added to form a bismuth sulfide heterojunction in situ, and sodium carbonate is added to inhibit the conversion of bismuth oxycarbonate into other structures as a comparison. At the same time, argon is used to replace the air in step A of Example 1, and sulfur hexafluoride is degraded under an argon atmosphere. The results are shown in Table 1.

[0067] Table 1 Degradation amount of different additives

[0068] additive Amount of additive substance / mmol Sulfur hexafluoride degradation amount / mmol / g <![CDATA[Na 2 S]]> 0.5 0.25 <![CDATA[Na 2 SO 3 ]]> 0.5 0.19 <![CDATA[Na 2 S 2 THE 3 ]]> 0.5 1.39 <![CDATA[Na 2 S-Na 2 SO 3 Mixture]]> 0.5-0.5 0.77 <![CDATA[Na 2 CO 3 ]]> 0.5 0.05

[0069] Example 5

[0070] The bismuth-based heterojunction catalytic material preparation method, processing device and processing method of Example 1a are different from those of Example 1 in that: in step A, argon is used instead of air, and its effect on degradation efficiency is tested under argon atmosphere. The results are as follows: Fig.13 shown.

[0071] Example 6

[0072] The Na prepared in Example 1 2 S@Bi 2 O 2 CO 3 (prepared with 0.5M sodium sulfide solution), Na 2 S 2 O 3 @Bi 2 O 2 CO 3 、NaI@Bi 2 O 2 CO 3 And the commercially available Bi2 O 2 CO 3 and Bi 2 O 12 W 3 The degradation of sulfur hexafluoride as a catalyst is different from the process of Example 1 in that in step A, argon is used instead of air, and its effect on the degradation efficiency is tested under an argon atmosphere. The results are shown in Table 2.

[0073] Table 2 Degradation amount of different bismuth-based and heterojunction catalysts

[0074] catalyst Sacrificial agent Sulfur hexafluoride degradation amount / mmol / g <![CDATA[Na 2 S@Bi 2 O 2 CO 3 ]]> Methanol 1.15 <![CDATA[Na 2 S 2 O 3 @Bi 2 O 2 CO 3 ]]> Methanol 0.98 <![CDATA[NaI@Bi 2 O 2 WHAT 3 ]]> Methanol 0.65 <![CDATA[Bi 2 O 2 WHAT 3 ]]> Methanol 0.42 <![CDATA[Bi 2 O 12 W 3 ]]> Methanol 0.42

[0075] Example 7

[0076] The Na prepared in Example 1 2 S@Bi 2 O 2 CO 3 (prepared with 0.5M sodium sulfide solution) was used as a catalyst to degrade sulfur hexafluoride. The difference from the process in Example 1 is that the organic solvent acetonitrile is replaced by the same volume of THF or DMSO or DMF; or the sacrificial agent methanol is replaced by triethanolamine or ethanolamine or benzyl alcohol or ascorbic acid, and the effect on the degradation efficiency is tested in an air atmosphere. When the sacrificial agent is replaced by ascorbic acid, its dosage is 0.5 mmol. The results are shown in Table 3.

[0077] Table 3 Effects of different solvents and sacrificial agents on degradation

[0078] Solvents Sacrificial agent Sulfur hexafluoride degradation amount / mmol / g <![CDATA[THF+H 2 The]]> Methanol 0.013 <![CDATA[DMSO+H 2 The]]> Methanol 0.043 <![CDATA[DMF+H 2 The]]> Methanol 0 <![CDATA[Acetonitrile + H 2 O]]> Triethanolamine 0.12 <![CDATA[Acetonitrile + H 2 O]]> Ethanolamine 0.09 <![CDATA[Acetonitrile + H 2 O]]> ascorbic acid 0.14 <![CDATA[Acetonitrile + H 2 O]]> Benzyl alcohol 0.21 <![CDATA[Acetonitrile + H 2 O]]> Methanol 0.43

[0079] DFT calculations revealed that after sulfur hexafluoride is adsorbed onto the bismuth carbonate interface, the SF bond length is Extend to At the same time, part of the electrons on the bottom F atom are also transferred to the top Bi atom. This means that the valence electrons of the fluorine atom in sulfur hexafluoride enter the bismuth oxycarbonate, and the empty orbital of the bismuth atom is the fundamental reason for the adsorption ( Figure 1-2 Then, 0.1g of the catalyst was weighed and tested with a gas adsorption instrument in a 25-degree water bath. The adsorption behavior of sulfur hexafluoride was verified by a room temperature sulfur hexafluoride gas desorption experiment. The catalyst adsorbed 7.4μmol / g of sulfur hexafluoride, which means that bismuth oxycarbonate can physically adsorb sulfur hexafluoride ( Figure 3 ).

[0080] Depend on Figure 3 and Figure 4 The prepared Na 2 S@Bi 2 O 2 CO 3The heterojunction material has better sulfur hexafluoride adsorption performance than commercial bismuth oxycarbonate before treatment.

[0081] Therefore, bismuth oxycarbonate can be used as a photocatalyst to generate reduction electrons for the reduction of sulfur hexafluoride, thereby reducing the energy required for the reaction. The addition of a hole sacrificial agent ensures the continued separation of photogenerated charge carriers into the reaction involving electrons and holes.

[0082] Comparative Example 1

[0083] A process for treating sulfur hexafluoride, which differs from Example 1 (3) only in that the sacrificial agent methanol is deleted; and the heterojunction activity is drastically reduced.

[0084] Comparative Example 2

[0085] A process for treating sulfur hexafluoride, which is different from Example 2 only in that the sacrificial agent methanol is deleted; the catalyst is inactive and cannot degrade sulfur hexafluoride.

[0086] Comparative Example 3

[0087] A process for treating sulfur hexafluoride, which is different from Example 2 only in that water is deleted; no reduction in the amount of sulfur hexafluoride is detected, and the catalyst cannot degrade sulfur hexafluoride.

[0088] Comparative Example 4

[0089] A process for treating sulfur hexafluoride, which is different from Example 2 only in that acetonitrile is deleted; no reduction in the amount of sulfur hexafluoride is detected, and the catalyst cannot degrade sulfur hexafluoride.

[0090] Comparative Example 5

[0091] A process for treating sulfur hexafluoride, which is different from Example 1 (3) only in that: the 365nm 50W LED light source is used to treat for 6 hours at room temperature instead of at 100°C in the dark. The catalyst is inactive and cannot degrade sulfur hexafluoride.

[0092] Fig.15 In order to replace the hydrogen-containing reagents (water, acetonitrile, methanol) in Example 2 with the corresponding deuterated reagents, after reacting in an air atmosphere for 16 hours, the liquid after filtering the solid 19 The F NMR spectrum shows that fluorinated products are generated during the reaction (CH becomes CF).

[0093] The above embodiments are only used to illustrate the technical solutions of the present invention, rather than to limit the same. Although the present invention has been described in detail with reference to the aforementioned embodiments, those skilled in the art should understand that the technical solutions described in the aforementioned embodiments may still be modified, or some of the technical features may be replaced by equivalents. However, these modifications or replacements do not deviate the essence of the corresponding technical solutions from the spirit and scope of the technical solutions of the embodiments of the present invention.

Claims

1. Application of a bismuth-based compound in photocatalytic degradation of sulfur hexafluoride, characterized in that: The bismuth-based compound is one of bismuth oxycarbonate, bismuth tungstate, a bismuth oxycarbonate mixture, and a bismuth-based heterojunction; the bismuth oxycarbonate mixture is a mixture of one or more of Na2S, Na2SO3, Na2S2O3, and NaI with bismuth oxycarbonate; the bismuth-based heterojunction is formed by mixing a solution containing one or more of sodium sulfide, NaI, Na2SO3, and Na2S2O3 with bismuth oxycarbonate and then drying.

2. The use of the bismuth-based compound according to claim 1 in photocatalytic degradation of sulfur hexafluoride, characterized in that: A bismuth-based compound is used as a catalyst, water and an organic solvent are used as a mixed solvent, and a sacrificial agent and sulfur hexafluoride are used as raw materials to react to obtain a fluorination product.

3. The use of the bismuth-based compound according to claim 1 in photocatalytic degradation of sulfur hexafluoride, characterized in that: In the bismuth-based heterojunction, the usage ratio of one or more of Na2S, Na2SO3, Na2S2O3, and NaI to bismuth oxycarbonate is 0.002-0.02 mol:1 g; in the bismuth oxycarbonate mixture, the usage ratio of one or more of Na2S, Na2SO3, Na2S2O3, and NaI to bismuth oxycarbonate is 0.5-1 mmol:30 mg.

4. The use of the bismuth-based compound according to claim 1 in photocatalytic degradation of sulfur hexafluoride, characterized in that: The stirring temperature is room temperature and the stirring time is 1 h.

5. A method for photocatalytic degradation of sulfur hexafluoride, characterized in that: The following steps are involved: The bismuth-based compound according to any one of claims 1 to 4, a mixed solvent and a sacrificial agent are mixed, sulfur hexafluoride gas is introduced, and the reaction is carried out under light conditions; wherein the mixed solvent is a mixture of water and an organic solvent.

6. The method for photocatalytic degradation of sulfur hexafluoride according to claim 5, characterized in that: The sacrificial agent is a mixture of one or more of triethanolamine, ethanolamine, methanol, benzyl alcohol, and ascorbic acid; and the organic solvent is a mixture of one or more of THF, DMSO, and acetonitrile.

7. The method for photocatalytic degradation of sulfur hexafluoride according to claim 5, characterized in that: If the sacrificial agent is a liquid, the dosage ratio of the bismuth-based compound and the sacrificial agent is 30-135 mg: 0.5 ml; the volume ratio of the mixed solvent to the sacrificial agent is 5: 1; if the sacrificial agent is a solid, the dosage ratio of the bismuth-based compound and the sacrificial agent is 30-135 mg: 0.5 mmol; the dosage ratio of the mixed solvent to the sacrificial agent is 2.5 ml: 0.5 mmol.

8. The method for photocatalytic degradation of sulfur hexafluoride according to claim 5, characterized in that: The sulfur hexafluoride gas is a mixed gas of sulfur hexafluoride and a filling gas, and the volume concentration of sulfur hexafluoride is 3-10 vol.%; the reaction temperature is room temperature, and the light source includes one or both of an LED ultraviolet lamp and a xenon lamp.

9. The method for photocatalytic degradation of sulfur hexafluoride according to claim 8, characterized in that: The filling gas is a mixture of one or more of argon, air, nitrogen and oxygen.

10. The method for photocatalytic degradation of sulfur hexafluoride according to any one of claims 5 to 9, characterized in that: The light source is a 50W, 365nm LED UV lamp.

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