A core-shell structured catalyst, a preparation method thereof, and a method for photocatalytic decomposition of hydrogen sulfide

Abstract

This invention discloses a core-shell structured catalyst, its preparation method, and a method for photocatalytic decomposition of hydrogen sulfide, belonging to the field of hydrogen sulfide catalytic decomposition technology. The core-shell structured catalyst of this invention comprises a Cu metal nanoparticle core structure and a nitrogen-doped carbon shell structure surrounding the Cu metal nanoparticle core structure, denoted as a Cu@N-C catalyst. The Cu@N-C catalyst provided by this invention can directly catalyze the decomposition of hydrogen sulfide to produce hydrogen and sulfur under photocatalytic conditions, exhibiting a high hydrogen production rate and good stability, and its catalytic activity can be completely restored through simple thermal activation.

Description

Technical Field

[0001] This invention belongs to the field of hydrogen sulfide catalytic decomposition technology, specifically relating to a core-shell structured catalyst, its preparation method, and a method for photocatalytic decomposition of hydrogen sulfide. Background Technology

[0002] Hydrogen sulfide is a toxic, foul-smelling, and corrosive hazardous and polluting gas. Even at extremely low concentrations of 10 ppm, it can harm the environment and human health. It exists in large quantities in nature and is also produced in large quantities during industrial processes. Global production currently exceeds 10 million tons annually and is gradually increasing, posing a significant challenge to energy transportation and utilization. Safely removing this gas from processes is crucial for human health, environmental protection, and process safety. At the same time, hydrogen sulfide is also a potential source of hydrogen and elemental sulfur, possessing significant potential economic value. The effective treatment and full utilization of hydrogen sulfide is of great and far-reaching significance.

[0003] The Claus process is the most commonly used method for removing hydrogen sulfide in industry. However, this process requires extremely high reaction temperatures (exceeding 1000℃), resulting in high energy consumption and complex processes. Furthermore, it oxidizes hydrogen sulfide into water, causing significant resource waste. Direct decomposition of hydrogen sulfide, on the other hand, not only eliminates pollution but also simultaneously produces high-value-added products such as hydrogen and sulfur, offering both environmental and economic benefits. It also boasts a relatively simple process flow, requiring no oxidation or combustion, and producing no byproducts, thus attracting widespread attention. In recent years, various technologies for hydrogen production from hydrogen sulfide have been explored, including thermocatalysis, plasma-induced processes, electrochemical routes, and microwave irradiation. However, these methods generally suffer from high energy consumption, poor catalyst stability, and complex reaction equipment.

[0004] Photocatalysis is an effective means of addressing energy and environmental issues by utilizing abundant and clean solar energy for chemical conversion, such as energy transformation and pollutant degradation. Plasmon photocatalysis, in particular, allows for the direct decomposition of gaseous and solid-phase hydrogen sulfide under mild reaction conditions using relatively simple and safe reaction equipment. Minghe Lou et al. used gold nanoparticles loaded onto silica as a plasmon photocatalyst, decomposing hydrogen sulfide into hydrogen and sulfur under illumination, achieving a hydrogen yield of 18000 μmol·g⁻¹. -1 ·h -1 However, gold is expensive, and catalysts have stability issues. CN117960217A uses cadmium sulfide, a semiconductor material supported by two-dimensional plasmonic material few-layer molybdenum carbide, as a catalyst for the photocatalytic direct decomposition of hydrogen sulfide, achieving a hydrogen yield as high as 49148 μmol·g. -1 ·h -1However, the relatively complex preparation method of few-layer molybdenum carbide, the biotoxicity and environmental pollution risks of the heavy metal cadmium, and the still existing stability issues all limit the application of this catalyst.

[0005] It is evident that developing a simple, low-cost, efficient, and stable plasmonic photocatalyst to achieve efficient and stable direct decomposition of hydrogen sulfide is of great significance. Summary of the Invention

[0006] The purpose of this invention is to address the problems of complex catalyst preparation, low catalyst activity, and catalyst instability in the direct decomposition reaction of hydrogen sulfide under existing technologies, and to propose a novel photocatalyst that can decompose hydrogen sulfide into hydrogen and sulfur under relatively mild reaction conditions, and the catalyst has high activity and good stability during use.

[0007] To achieve the above objectives, the present invention provides a core-shell structured catalyst, a method for preparing the same, and a method for photocatalytic decomposition of hydrogen sulfide. The core-shell structured catalyst comprises a Cu metal nanoparticle core structure and a nitrogen-doped carbon shell structure surrounding the Cu metal nanoparticle core structure. The core-shell structured catalyst is denoted as Cu@NC. The method comprises using the core-shell structured catalyst to photocatalytically decompose hydrogen sulfide directly to generate hydrogen and sulfur.

[0008] A method for preparing a core-shell structured catalyst includes the following steps:

[0009] (1) Cu(NO3)2.3H2O was loaded onto SBA-15 molecular sieve by impregnation. Cu(NO3)2.3H2O was dissolved in deionized water, and then SBA-15 was added. The mixture was then heated and stirred for impregnation to obtain the precursor Cu(NO3)2 / SBA-15.

[0010] (2) The Cu(NO3)2 in the precursor is reduced to Cu nanoparticles by hydrogen gas, and then the Cu nanoparticles are coated with a nitrogen-doped carbon shell by chemical vapor deposition (CVD). The precursor Cu(NO3)2 / SBA-15 is placed in a tube furnace and heated for reduction in a mixed atmosphere containing hydrogen gas. After reduction, it is heated in situ in an inert atmosphere and acetonitrile is bubbled in to obtain Cu@NC / SBA-15.

[0011] (3) Place the Cu@NC / SBA-15 in an alkaline solution, stir and wash away the SBA-15 to obtain a core-shell catalyst, labeled as Cu@NC;

[0012] The core-shell structured catalyst comprises a Cu metal nanoparticle core structure and a nitrogen-doped carbon shell structure surrounding the Cu metal nanoparticle core structure.

[0013] In one specific embodiment, the ratio of Cu(NO3)2·3H2O to SBA-15 in step (1) is 3.6-14.4 mmol·g. -1 .

[0014] In one specific implementation, the ratio of Cu(NO3)2.3H2O to deionized water in step (1) is 28.8-172.8 mmol: 200 ml.

[0015] In one specific implementation, the amount of deionized water used in step (1) is 50-300ml, and the amount of SBA-15 molecular sieve is 2-12g.

[0016] In one specific implementation, the immersion heating temperature in step (1) is 25-100℃, and the immersion time is 3-24h.

[0017] In one specific embodiment, the mixed atmosphere containing hydrogen in step (2) is hydrogen / argon, and the volume ratio of hydrogen / argon in the mixed atmosphere is 20:80-80:20, more preferably 50:50.

[0018] In one specific embodiment, the hydrogen reduction temperature in step (2) is 300-500℃, more preferably 300℃, and the hydrogen reduction time is 0.5-3h, more preferably 1h.

[0019] In one specific implementation, the inert atmosphere in step (2) is an argon atmosphere.

[0020] In one specific embodiment, the temperature for chemical vapor deposition of acetonitrile in step (2) is 600-1000°C.

[0021] In one specific embodiment, the inert atmosphere flow rate relative to the precursor Cu(NO3)2 / SBA-15 during step (2) when acetonitrile is bubbled in is 30-60 mL·min. -1 ·g -1 .

[0022] In one specific embodiment, the time for acetonitrile to be bubbled in step (2) is 5-40 minutes, more preferably 20-40 minutes.

[0023] In one specific embodiment, the alkaline solution in step (3) is a 1-4M NaOH solution, and the stirring time is 3-24h.

[0024] Core-shell structured catalysts prepared by any of the above methods.

[0025] The above-described method for photocatalytic direct decomposition of hydrogen sulfide using a core-shell structured catalyst includes filling a core-shell structured catalyst bed in a quartz reactor, introducing pure hydrogen sulfide gas into the catalyst bed, and performing a photocatalytic reaction in which hydrogen sulfide is directly decomposed into hydrogen and sulfur under laser irradiation.

[0026] In one specific embodiment, the photocatalytic reaction is carried out under laser irradiation, using a laser wavelength of 405-660 nm and a light power density of 2.5-17.5 W·cm⁻¹. -2 .

[0027] In one specific embodiment, the space velocity during the photocatalytic reaction is 1200-240000 mL·g. cat -1 ·h -1 .

[0028] In one specific embodiment, after the catalyst's activity decreases during the photocatalytic reaction, it can be reactivated by heating under an inert atmosphere, which is one or more of nitrogen, argon, and helium. The heating temperature is 200-800℃, and the heating time is 1-5 hours.

[0029] Compared with the prior art, the present invention has the following advantages and beneficial effects:

[0030] (1) The core-shell structured catalyst Cu@NC in this invention exhibits excellent catalytic activity and regenerability when catalyzing the direct decomposition of hydrogen sulfide into hydrogen and sulfur under photocatalytic conditions, at 17.5 W·cm⁻¹. -2 Under laser irradiation, the yield of hydrogen can reach 90,478 μmol·g. -1 ·h -1 Compared with similar catalysts, it has a significant improvement, and because it can be deactivated by sulfur deposition, its catalytic activity can be restored by simple thermal regeneration, exhibiting good stability and regenerability.

[0031] (2) The present invention prepared a core-shell structure Cu@NC catalyst. Copper nanoparticles wrapped in multilayer nitrogen-doped carbon were synthesized by chemical vapor deposition and used as catalysts. The carbon layer protects the copper nanoparticles, which solves the problem of unstable copper chemical properties. Compared with Cu / C catalysts, the hydrogen production rate and stability are greatly improved. The structure is clear and the preparation is simple. The raw materials are readily available and the cost is low. It does not require the use of precious metals and complex preparation processes, and has good application prospects.

[0032] (3) This invention uses Cu@NC catalyst to achieve efficient direct decomposition of hydrogen sulfide under visible light catalysis. The reaction conditions are relatively mild and do not require external heating. The catalytic activity is significantly higher than that of thermal catalysis at the same temperature. This provides new ideas for the effective utilization of solar energy, the synthesis and application of new photocatalysts, and the safe and efficient decomposition of hydrogen sulfide. Attached Figure Description

[0033] Figure 1 This is a transmission electron microscope (TEM) image of Cu@NC for 30 min in Example 1.

[0034] Figure 2 This is a statistical diagram of the number of carbon layers in the Cu@NC catalyst for 10-40 min in Examples 1 and 3. Detailed Implementation

[0035] The present invention will be described in detail below with reference to the accompanying drawings and embodiments, but these embodiments should not be considered as limiting the present invention.

[0036] Example 1:

[0037] A method for preparing a core-shell structured catalyst Cu@NC, wherein the catalyst is prepared by the following method:

[0038] Step (1): Dissolve 57.6 mmol Cu(NO3)2·3H2O in 200 ml of deionized water, add 8 g of SBA-15, heat to 100 °C and stir for 6 h, then filter and wash to obtain the precursor Cu(NO3)2 / SBA-15.

[0039] Step (2): Take 2g of the precursor Cu(NO3)2 / SBA-15 and place it in a tube furnace, then heat it at 80mL·min. -1 A 50:50 hydrogen / argon mixture was introduced, and the mixture was heated to 300°C for 1 hour under this atmosphere, followed by reduction at a rate of 80 mL / min. -1 Argon gas is introduced at a flow rate, and the temperature is heated in situ to 800°C using 80 mL / min. -1 Argon gas was bubbled into acetonitrile for 30 minutes to obtain Cu@NC / SBA-1530min.

[0040] Step (3): Place the Cu@NC / SBA-15 30min in 100ml of 2M NaOH solution, stir for 12h to wash away SBA-15, and then wash and dry to obtain the catalyst Cu@NC 30min.

[0041] Figure 1The image shows a transmission electron microscope (TEM) image of Cu@NC for 30 min in Example 1 of this invention. It can be observed from the image that the Cu nanoparticles have a particle size of about 10 nm and are wrapped in a multi-layer carbon shell structure. The interplanar spacing is measured to be 0.2077 nm, which is consistent with the Cu (111) crystal plane. This indicates that the carbon shell has a good protective ability. Under its protection, the core of the Cu nanoparticles is prevented from being oxidized and maintains the Cu elemental state.

[0042] A method for applying the core-shell structured catalyst Cu@NC to the photocatalytic direct decomposition of hydrogen sulfide to produce hydrogen and sulfur:

[0043] The Cu@NC 30min catalyst prepared above was packed into a quartz reactor at a loading volume of 5 mg, and then injected at a rate of 10 mL / min. -1 A flow rate of 99.9% hydrogen sulfide gas is introduced, and then the catalyst bed is irradiated with laser light to directly decompose the hydrogen sulfide. The reaction is carried out at atmospheric pressure, with a laser wavelength of 577 nm and a power density of 2.5-17.5 W·cm⁻¹. -2 The hydrogen production rates of this catalyst under laser irradiation at a wavelength of 577 nm and different optical power densities are shown in Table 1. The rates at a wavelength of 577 nm and a laser power density of 12.5 W / cm² are also shown in Table 1. 2 Table 4 shows the hydrogen production rate and activity decay over 1 hour under laser irradiation.

[0044] Table 1

[0045] <![CDATA[Optical power density (W / cm 2 ).]]> <![CDATA[H2 production rate (μmol·g -1 ·h -1 )]]> 5 600 7.5 3584 10 17459 12.5 42333 15 64521 17.5 90478

[0046] Table 1 shows that the hydrogen production rate increases with increasing optical power density, reaching a maximum at an optical power density of 17.5 W·cm⁻¹. -2 At that time, the hydrogen production rate reached as high as 90,478 μmol·g. -1 ·h -1 .

[0047] Comparative Example 1:

[0048] A Cu / C catalyst with Cu metal particles simply supported on a C support is prepared and its application in the photocatalytic direct decomposition of hydrogen sulfide to produce hydrogen and sulfur is disclosed. The catalyst is synthesized by an impregnation method and prepared using the following method:

[0049] 0.944 g of Cu(NO3)2·3H2O was dissolved in 50 mL of deionized water to form a solution. 500 mg of carbon support was added to this solution and the mixture was stirred for 6 h. The solution was then freeze-dried for 24 h to obtain the precursor 50% Cu(NO3)2 / C. The 50% Cu(NO3)2 / C precursor was then transferred to a tube furnace and dried at 80 mL / min. -1A 50:50 hydrogen / argon mixture was introduced, and the mixture was heated to 300°C for 1 hour under this atmosphere, followed by reduction at a rate of 80 mL / min. -1 Argon gas was introduced at a certain flow rate, and the mixture was heated in situ to 800°C and held for 30 minutes to obtain a 50% Cu / C catalyst.

[0050] A 50% Cu / C catalyst was used for the photocatalytic direct decomposition of hydrogen sulfide. The 50% Cu / C catalyst described in Comparative Example 1 was filled into a quartz reactor at a loading of 5 mg, and then the catalyst was reacted at a rate of 10 mL / min. -1 A flow rate of 99.9% H2S gas was introduced, and then the catalyst bed was irradiated with laser light to directly decompose hydrogen sulfide. The reaction was carried out at atmospheric pressure, with a laser wavelength of 577 nm and a power density of 12.5 W·cm⁻¹. -2 The hydrogen production rate and activity decay over 1 hour are shown in Table 2.

[0051] Table 2

[0052] Sample Name <![CDATA[H2 production rate (μmol·g -1 ·h -1 )]]> It decayed to 1 hour later Cu@NC 30min 42333 93.4% 50% Cu / C 22967 28.4%

[0053] Based on the catalytic results of Example 1 and Comparative Example 1 above, the catalyst Cu@NC prepared in this invention, consisting of a Cu metal nanoparticle core structure and a nitrogen-doped carbon shell structure wrapped around it, exhibits improved catalytic activity for hydrogen sulfide decomposition due to the surface enhancement of nitrogen-doped carbon. The carbon shell structure also effectively protects the Cu core from corrosion by hydrogen sulfide gas. Compared to the 50% Cu / C catalyst, both the hydrogen production rate and catalyst stability are significantly improved.

[0054] Comparative Example 2:

[0055] A method for preparing an improved Cu / C catalyst with Cu metal particles simply supported on a C support and its application in the photocatalytic direct decomposition of hydrogen sulfide to produce hydrogen and sulfur. The catalyst is synthesized using a wet impregnation method and prepared by the following method:

[0056] 1.094 g of Cu(NO3)2·3H2O was dissolved in 0.55 mL of deionized water. This solution was then dropwise impregnated onto 500 mg of carbon support. The mixture was ground for 10 min and then dried at 100 °C for 12 h to obtain the precursor 58% Cu(NO3)2 / C. The 58% Cu(NO3)2 / C precursor was then transferred to a tube furnace and heated at 80 mL / min. -1 A 50:50 hydrogen / argon mixture was introduced, and the mixture was heated to 300°C for 1 hour under this atmosphere, followed by reduction at a rate of 80 mL / min. -1 Argon gas was introduced at a certain flow rate, and the mixture was heated in situ to 800°C and held for 30 minutes to obtain a 58% Cu / C catalyst.

[0057] A 58% Cu / C catalyst was used for the photocatalytic direct decomposition of hydrogen sulfide. The 58% Cu / C catalyst described in Comparative Example 2 was filled into a quartz reactor at a loading of 5 mg, and then the catalyst was reacted at a rate of 10 mL / min. -1 A flow rate of 99.9% H2S gas was introduced, and then the catalyst bed was irradiated with laser light to directly decompose hydrogen sulfide. The reaction was carried out at atmospheric pressure, with a laser wavelength of 577 nm and a power density of 12.5 W·cm⁻¹. -2 The hydrogen production rate and activity decay over 1 hour are shown in Table 3.

[0058] Table 3

[0059] Sample Name <![CDATA[H2 production rate (μmol·g -1 ·h -1 ).]]> It decayed to 1 hour later 58% Cu / C 13788 51.4% Cu@NC 30min 42333 93.4% 50% Cu / C 22967 28.4%

[0060] The catalytic results of Comparative Example 2 show that the 58% Cu / C catalyst with the same Cu loading prepared by the initial wet impregnation method has improved stability compared to the 50% Cu / C catalyst prepared by the ordinary impregnation method, but the hydrogen production rate is significantly reduced. In contrast, the Cu@NC catalyst prepared in this invention shows significant improvements in both hydrogen production rate and stability compared to the two comparative examples. This further demonstrates that the core-shell structure catalyst of this invention, with its nitrogen-doped carbon layer encapsulating Cu metal nanoparticles, significantly improves hydrogen production rate and catalyst stability, exhibiting clear advantages.

[0061] Example 2:

[0062] A method for stability analysis and reactivation to restore activity of a core-shell structured catalyst Cu@NC in the photocatalytic direct decomposition of hydrogen sulfide:

[0063] The Cu@NC 30min catalyst prepared in Example 1 was packed into a quartz reactor at a loading volume of 5 mg, and then injected at a rate of 10 mL / min. -1 A flow rate of 99.9% hydrogen sulfide gas is introduced, and then the catalyst bed is irradiated with laser light to directly decompose the hydrogen sulfide. The reaction is carried out at atmospheric pressure, with a laser wavelength of 577 nm and a power density of 2.5-17.5 W·cm⁻¹. -2 .

[0064] After the catalyst activity decreased, it was reactivated by passing 20 mL / min through a quartz reactor. -1 Nitrogen gas was heated to 500℃ and held for 1 hour.

[0065] During photocatalysis, the hydrogen production rate decreases over time due to the deposition of sulfur, one of the products. However, it can be reactivated by simply heating in a nitrogen atmosphere. After reactivation, the catalytic activity can be completely restored, which further demonstrates that the strong protective ability of the carbon shell for the Cu core makes the catalyst very stable during the reaction.

[0066] Example 3:

[0067] A method for preparing Cu@NC catalysts under different CVD time conditions and applying them to the photocatalytic direct decomposition of hydrogen sulfide to produce hydrogen and sulfur:

[0068] Step (1): Dissolve 57.6 mmol Cu(NO3)2·3H2O in 200 ml of deionized water, add 8 g of SBA-15, heat to 100 °C and stir for 6 h, then filter and wash to obtain the precursor Cu(NO3)2 / SBA-15.

[0069] Step (2): Take 2g of the precursor Cu(NO3)2 / SBA-15 and place it in a tube furnace, then heat it at 80mL·min. -1 A 50:50 hydrogen / argon mixture was introduced, and the mixture was heated to 300°C for 1 hour under this atmosphere, followed by reduction at a rate of 80 mL / min. -1 Argon gas is introduced at a flow rate, and the temperature is heated in situ to 800°C using 80 mL / min. -1 Argon gas was bubbled into acetonitrile for 10, 20, and 40 minutes to obtain Cu@NC / SBA-15 for 10 min, Cu@NC / SBA-15 for 20 min, and Cu@NC / SBA-15 for 40 min.

[0070] Step (3): Place the obtained Cu@NC / SBA-15 in 100ml of 2M NaOH solution, stir for 12h to wash away SBA-15, and then wash and dry to obtain catalysts Cu@NC 10min, Cu@NC 20min, and Cu@NC 40min.

[0071] Cu@NC catalysts with different CVD times were used for the photocatalytic direct decomposition of hydrogen sulfide. In Example 3, Cu@NC catalysts with different CVD times were packed into a quartz reactor at a loading of 5 mg, and then discharged at a rate of 10 mL / min. -1 A flow rate of 99.9% H2S gas was introduced, and then the catalyst bed was irradiated with laser light to directly decompose hydrogen sulfide. The reaction was carried out at atmospheric pressure, with a laser wavelength of 577 nm and a power density of 12.5 W·cm⁻¹. -2 The hydrogen production rate and activity decay over 1 hour are shown in Table 4.

[0072] Figure 2The carbon layer count of the Cu@NC catalyst in Examples 1 and 3 of this invention from 10 to 40 min was obtained by statistically analyzing the carbon layer encapsulation in dozens of transmission electron microscopy (TEM) images. The figures show that as the CVD time increases from 10 min to 40 min, the number of carbon layers encapsulating the Cu nanoparticles changes significantly, gradually increasing from 1-3 layers at 10 min to 7-9 layers at 40 min.

[0073] Table 4

[0074] Sample Name <![CDATA[H2 production rate (μmol·g -1 ·h -1 )]]> It decayed to 1 hour later Cu@NC 10min 36210 74.3% Cu@NC 20min 38431 89.1% Cu@NC 30min 42333 93.4% Cu@NC 40min 31668 87.9%

[0075] Based on the catalytic results of Examples 1 and 3 above, the core-shell structured catalyst Cu@NC prepared in this invention can thicken the carbon shell layer encapsulating Cu nanoparticles with appropriate extension of CVD time, thereby enhancing the protection of the Cu nanoparticle core and significantly improving the catalyst stability.

[0076] Example 4:

[0077] A method for preparing Cu@NC catalysts with low loading and low impregnation temperature at different CVD times, and applying them to the photocatalytic direct decomposition of hydrogen sulfide to produce hydrogen and sulfur:

[0078] Step (1): Dissolve 7.2 mmol Cu(NO3)2·3H2O in 50 ml of deionized water, add 2 g SBA-15, stir and soak at 25 °C for 6 h, and then filter and wash to obtain the precursor Cu(NO3)2 / SBA-15.

[0079] Step (2): Take 2g of the precursor Cu(NO3)2 / SBA-15 and place it in a tube furnace, then heat it at 80mL·min. -1 A 50:50 hydrogen / argon mixture was introduced, and the mixture was heated to 300°C for 1 hour under this atmosphere, followed by reduction at a rate of 80 mL / min. -1 Argon gas is introduced at a flow rate, and the temperature is heated in situ to 800°C using 80 mL / min. -1 Argon gas was bubbled into acetonitrile for 5 minutes to obtain Cu@NC / SBA-15 for 5 minutes.

[0080] Step (3): Place the Cu@NC / SBA-15 in 50 ml of 2 M NaOH solution, stir for 12 h to wash away SBA-15, and then wash and dry to obtain the catalyst Cu@NC 5 min.

[0081] The Cu@NC 5min catalyst was used for the photocatalytic direct decomposition of hydrogen sulfide. The Cu@NC catalyst from Example 4 was packed into a quartz reactor at a loading of 5 mg, and then reacted at a rate of 10 mL / min. -1A flow rate of 99.9% H2S gas was introduced, and then the catalyst bed was irradiated with laser light to directly decompose hydrogen sulfide. The reaction was carried out at atmospheric pressure, with a laser wavelength of 577 nm and a power density of 12.5 W·cm⁻¹. -2 The hydrogen production rate and activity decay over 1 hour are shown in Table 5.

[0082] Table 5

[0083] Sample Name <![CDATA[H2 production rate (μmol·g -1 ·h -1 )]]> It decayed to 1 hour later Cu@NC 5min 33284 84.6%

[0084] Example 5:

[0085] A method for preparing Cu@NC catalysts under different CVD temperature conditions and applying them to the photocatalytic direct decomposition of hydrogen sulfide to produce hydrogen and sulfur:

[0086] Step (1): Dissolve 57.6 mmol Cu(NO3)2·3H2O in 200 ml of deionized water, add 8 g of SBA-15, heat to 100 °C and stir for 6 h, then filter and wash to obtain the precursor Cu(NO3)2 / SBA-15.

[0087] Step (2): Take 2g of the precursor Cu(NO3)2 / SBA-15 and place it in a tube furnace, then heat it at 80mL·min. -1 A 50:50 hydrogen / argon mixture was introduced, and the mixture was heated to 300°C for 1 hour under this atmosphere, followed by reduction at a rate of 80 mL / min. -1 Argon gas was introduced at a flow rate, and the mixture was heated in situ to 600, 900, and 1000 °C using 80 mL / min. -1 Argon gas was bubbled into acetonitrile for 30 minutes to obtain Cu@NC / SBA-15 at 600℃, Cu@NC / SBA-15 at 900℃, and Cu@NC / SBA-15 at 1000℃.

[0088] Step (3): Place the Cu@NC / SBA-15 in 100ml of 2M NaOH solution, stir for 12h to wash away SBA-15, and then wash and dry to obtain catalysts Cu@NC 600℃, Cu@NC 900℃, and Cu@NC 100℃.

[0089] Cu@NC catalysts at different CVD temperatures were used for the photocatalytic direct decomposition of hydrogen sulfide. In Example 5, Cu@NC catalysts at different CVD temperatures were packed into a quartz reactor at a loading of 5 mg, and then injected at a rate of 10 mL / min. -1A flow rate of 99.9% H2S gas was introduced, and then the catalyst bed was irradiated with laser light to directly decompose hydrogen sulfide. The reaction was carried out at atmospheric pressure, with a laser wavelength of 577 nm and a power density of 12.5 W·cm⁻¹. -2 The hydrogen production rate and activity decay over 1 hour are shown in Table 6.

[0090] Table 6

[0091] Sample Name <![CDATA[H2 production rate (μmol·g -1 ·h -1 ).]]> It decayed to 1 hour later Cu@NC 600℃ 39399 66.8% Cu@NC 900℃ 28915 89.4% Cu@NC 1000℃ 26564 80.9%

[0092] Example 6:

[0093] A method for preparing Cu@NC catalysts under different impregnation solution concentrations and applying them to the photocatalytic direct decomposition of hydrogen sulfide to produce hydrogen and sulfur:

[0094] Step (1): Dissolve 14.4-91.4 mmol Cu(NO3)2·3H2O in 100 ml of deionized water, then add 4 g of SBA-15, heat to 100 °C and stir for 6 h, then filter and wash to obtain the precursor Cu(NO3)2 / SBA-15 3.6 mmol·g -1 , Cu(NO3)2 / SBA-15 7.2mmol·g -1 , Cu(NO3)2 / SBA-15 14.4mmol·g -1 , Cu(NO3)2 / SBA-1521.6mmol·g -1 .

[0095] Step (2): Place more than 2g of the prepared precursor Cu(NO3)2 / SBA-15 in a tube furnace and heat at 80mL·min. -1 A 50:50 hydrogen / argon mixture was introduced, and the mixture was heated to 300°C for 1 hour under this atmosphere, followed by reduction at a rate of 80 mL / min. -1 Argon gas is introduced at a flow rate, and the temperature is heated in situ to 800°C using 80 mL / min. -1 Argon gas was bubbled into acetonitrile for 10 minutes to obtain Cu@NC / SBA-15 3.6 mmol·g. -1 Cu@NC / SBA-15 7.2 mmol·g -1 Cu@NC / SBA-15 14.4 mmol·g -1 Cu@NC / SBA-15 21.6 mmol·g -1 .

[0096] Step (3): Place the Cu@NC / SBA-15 in 100 ml of 2 M NaOH solution, stir for 12 h to wash away SBA-15, and then wash and dry to obtain catalyst Cu@NC 3.6 mmol·g. -1 Cu@NC 7.2mmol·g -1 Cu@N-C 14.4 mmol·g -1 Cu@NC 21.6mmol·g -1 .

[0097] Cu@NC catalysts with different impregnation solution concentrations were used for the photocatalytic direct decomposition of hydrogen sulfide. In Example 6, Cu@NC catalysts with different impregnation solution concentrations were filled into a quartz reactor at a loading volume of 5 mg, and then injected at a rate of 10 mL / min. -1 A flow rate of 99.9% H2S gas was introduced, and then the catalyst bed was irradiated with laser light to directly decompose hydrogen sulfide. The reaction was carried out at atmospheric pressure, with a laser wavelength of 577 nm and a power density of 12.5 W·cm⁻¹. -2 The hydrogen production rate and activity decay over 1 hour are shown in Table 7.

[0098] Table 7

[0099] Sample Name <![CDATA[H2 production rate (μmol·g -1 ·h -1 ).]]> It decayed to 1 hour later <![CDATA[Cu@N-C 3.6mmol·g -1 ]]> 27601 91.2% <![CDATA[Cu@N-C 7.2mmol·g -1 ]]> 25743 83.7% <![CDATA[Cu@N-C14.4mmol·g -1 ]]> 28456 82.8% <![CDATA[Cu@N-C 21.6mmol·g -1 ]]> 59097 1.8%

[0100] In summary, this invention proposes a method for preparing a core-shell structured catalyst, Cu@NC, and its application in the photocatalytic direct decomposition of hydrogen sulfide to produce hydrogen and sulfur. The Cu@NC catalyst comprises a Cu metal nanoparticle core that interacts with light to activate a carbon shell through thermionic and thermal effects; the nitrogen-doped carbon shell coats the Cu nanoparticles, protecting them from hydrogen sulfide corrosion and serving as a direct reaction site. The Cu@NC core-shell structured catalyst exhibits superior performance, showing significant improvements in both catalytic activity and stability compared to Cu / C catalysts under the same conditions. Furthermore, the catalytic activity and stability can be further modulated by adjusting the thickness of the carbon shell by varying the CVD time. Under optimal conditions (577 nm, 17.5 W·cm⁻¹), the Cu@NC core-shell structured catalyst achieves optimal performance. -2 The hydrogen production rate is as high as 90,478 μmol·g⁻¹. -1 ·h -1 Meanwhile, the catalyst operates at a high optical power density (577 nm, 12.5 W·cm). -2Even after 60 minutes of continuous reaction under irradiation, the catalyst retains 93.4% of its catalytic activity. The catalytic activity decreases due to sulfur deposition after prolonged photocatalytic reaction, but can be fully restored by simple thermal regeneration under an inert atmosphere. Therefore, the Cu@NC core-shell structure catalyst described in this invention is inexpensive and easy to prepare. It achieves efficient and direct decomposition of hydrogen sulfide under relatively mild reaction conditions without external heating, demonstrating good application potential and broad research prospects. It contributes to the effective utilization of solar energy, the synthesis and application of novel photocatalysts, and the safe and efficient decomposition of hydrogen sulfide.

[0101] The above are merely preferred embodiments of the present invention. The scope of protection of the present invention is not limited to the above embodiments. Various process solutions that are not substantially different from the concept of the present invention are all within the scope of protection of the present invention.

Claims

1. A method for preparing a core-shell structured catalyst, characterized in that, Includes the following steps: (1) Cu(NO3)2.3H2O was loaded onto SBA-15 molecular sieve by impregnation. Cu(NO3)2.3H2O was dissolved in deionized water, and then SBA-15 was added. The mixture was then heated and stirred for impregnation to obtain the precursor Cu(NO3)2 / SBA-15. (2) The Cu(NO3)2 in the precursor is reduced to Cu nanoparticles by hydrogen gas, and then the Cu nanoparticles are coated with a nitrogen-doped carbon shell by chemical vapor deposition. The precursor Cu(NO3)2 / SBA-15 is placed in a tube furnace and heated in a mixed atmosphere containing hydrogen gas for reduction. After reduction, it is heated in situ in an inert atmosphere and acetonitrile is bubbled in to obtain Cu@NC / SBA-15. (3) Place the Cu@NC / SBA-15 in an alkaline solution, stir and wash away the SBA-15 to obtain a core-shell structure catalyst, labeled as Cu@NC; The core-shell structured catalyst comprises a Cu metal nanoparticle core structure and a nitrogen-doped carbon shell structure surrounding the Cu metal nanoparticle core structure.

2. The method for preparing a core-shell structured catalyst according to claim 1, characterized in that, In step (2), the temperature for chemical vapor deposition by introducing acetonitrile is 600-1000℃, and the inert atmosphere flow rate relative to the precursor Cu(NO3)2 / SBA-15 during acetonitrile introduction is 30-60 mL·min. -1 ·g -1 The acetonitrile is introduced over a period of 5-40 minutes.

3. A method for preparing a core-shell structured catalyst according to claim 1 or 2, characterized in that, In step (1), the ratio of Cu(NO3)2·3H2O to SBA-15 is 3.6-14.4 mmol·g. -1 The immersion heating temperature is 25-100℃, and the immersion time is 3-24h.

4. A method for preparing a core-shell structured catalyst according to claim 1 or 2, characterized in that, In step (2), the mixed atmosphere containing hydrogen is hydrogen / argon, the volume ratio of hydrogen / argon in the mixed atmosphere is 20:80-80:20, the hydrogen reduction temperature is 300-500℃, and the hydrogen reduction time is 0.5-3h; the inert atmosphere is argon atmosphere.

5. A method for preparing a core-shell structured catalyst according to claim 1 or 2, characterized in that, In step (3), the alkaline solution is a 1-4M NaOH solution, and the stirring time is 3-24h.

6. A core-shell structured catalyst prepared by any one of claims 1 to 5.

7. The method for photocatalytic direct decomposition of hydrogen sulfide using the core-shell structured catalyst of claim 6, characterized in that, The method includes filling the core-shell structured catalyst bed in a quartz reactor, introducing pure hydrogen sulfide gas into the catalyst bed, and performing a photocatalytic reaction in which hydrogen sulfide is directly decomposed into hydrogen and sulfur under laser irradiation.

8. The method for photocatalytic direct decomposition of hydrogen sulfide using the core-shell structured catalyst according to claim 7, characterized in that, The photocatalytic reaction is carried out under laser irradiation with a wavelength of 405-660 nm and a power density of 2.5-17.5 W·cm⁻¹. -2 .

9. The method for photocatalytic direct decomposition of hydrogen sulfide using the core-shell structured catalyst according to claim 7, characterized in that, The space velocity during the photocatalytic reaction is 1200-240000 mL·g. cat -1 ·h -1 .

10. The method for photocatalytic direct decomposition of hydrogen sulfide using the core-shell structured catalyst according to claim 7, characterized in that, After the catalyst's activity decreases during the photocatalytic reaction, it can be reactivated by heating under an inert atmosphere, which is one or more of nitrogen, argon, and helium. The heating temperature is 200-800℃, and the heating time is 1-5h.

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