Solvent-based preparation of elemental sulfur from hydrogen sulfide and sulfur dioxide

Abstract

This application relates to the field of sulfur preparation technology, specifically disclosing a solvent method for preparing elemental sulfur from hydrogen sulfide and sulfur dioxide. In this solvent method, hydrogen sulfide and sulfur dioxide are introduced into a mixture of 2-acetylthiophene and 2-phenylthiophene at a temperature of 120-150°C to undergo a disproportionation reaction, generating elemental sulfur. This application uses the liquid mixture of 2-acetylthiophene and 2-phenylthiophene as the reaction medium, where hydrogen sulfide and sulfur dioxide react to produce sulfur and water. The carbonyl oxygen atom of 2-acetylthiophene and the sulfur atom on the thiophene ring have a certain electron-donating ability, which catalyzes the reaction. 2-Phenylthiophene has a high boiling point and stable properties, and can effectively disperse and transport liquid sulfur. After standing, the mixture of 2-acetylthiophene and 2-phenylthiophene easily separates from the liquid sulfur, thus facilitating the separation of elemental sulfur. Compared to the traditional Claus process, this solvent method, using a solvent as the reaction medium, is less prone to sulfur blockage problems.

Description

Technical Field

[0001] This application relates to the field of sulfur preparation technology, specifically disclosing the solvent method for preparing elemental sulfur from hydrogen sulfide and sulfur dioxide. Background Technology

[0002] The traditional method for recovering sulfur from hydrogen sulfide-containing tail gas involves first feeding about one-third of the tail gas and air into a high-temperature combustion furnace (above 1000℃) for incomplete combustion: H₂S + 1.5O₂ → SO₂ + H₂O. The generated SO₂ reacts with the remaining two-thirds of the tail gas in a partial Claus reaction at high temperatures within the furnace: 2H₂S + SO₂ → 3S + 2H₂O, producing gaseous sulfur (mainly S₂). The process gas exiting the combustion furnace (containing H₂S, SO₂, sulfur vapor, H₂O, etc.) undergoes heat recovery in a waste heat boiler, reducing its temperature to approximately 300℃. At this point, the gaseous sulfur condenses into liquid sulfur and is separated out. The remaining gas enters a fixed-bed reactor containing an alumina (Al₂O₃) or titanium-based (TiO₂) solid catalyst, where the Claus reaction continues at a lower temperature (200-350℃), generating more sulfur. After the reaction, the gas enters a condenser for cooling, and the liquid sulfur is separated again. Typically, two to three stages of "catalytic reaction + condensation separation" units are set up to gradually increase the total sulfur recovery rate.

[0003] Catalytic reactions are exothermic, and the ideal operating temperature needs to be above the sulfur dew point (i.e., the temperature at which sulfur begins to condense). If the catalyst bed temperature is not properly controlled—for example, if the inlet temperature is too low, or if the exothermic reaction causes uneven cooling after the bed overheats—the temperature in some areas will drop below the sulfur dew point. Once the temperature falls below the sulfur dew point, the generated sulfur vapor or sulfur molecules in the gas phase will condense into liquid sulfur within the tiny pores of the catalyst. Liquid sulfur has a high viscosity and will clog the active sites and pores of the catalyst. Once the pores are blocked, reactants (H2S, SO2) cannot diffuse to the active sites, and products cannot diffuse out, leading to rapid catalyst deactivation. Simultaneously, the condensed sulfur will cover the catalyst surface, forming a physical barrier. As sulfur continues to accumulate, the voids between catalyst particles are also blocked, causing a sharp increase in the pressure drop across the entire reactor bed, which in severe cases necessitates shutdown and catalyst replacement.

[0004] Sulfur blockage in the traditional Claus process is a long-term problem, stemming from its inherent "gas-phase reaction + subsequent condensation separation" model. The catalyst must operate within a narrow temperature window that generates sulfur and avoids sulfur condensation, which is difficult to control perfectly in actual operation. Therefore, frequent catalyst regeneration or replacement is a routine maintenance item. Summary of the Invention

[0005] Given that the traditional Claus process is prone to sulfur blockage, this application proposes a solvent-based process for preparing elemental sulfur from hydrogen sulfide and sulfur dioxide, employing the following technical solution to address the sulfur blockage problem.

[0006] Elemental sulfur is prepared from hydrogen sulfide and sulfur dioxide using a solvent method. Hydrogen sulfide and sulfur dioxide are passed into a mixture of 2-acetylthiophene and 2-phenylthiophene at a temperature of 120-150°C to undergo a disproportionation reaction, thereby generating elemental sulfur.

[0007] By adopting the above technical solution, this application uses a liquid mixture of 2-acetylthiophene and 2-phenylthiophene as the reaction medium. Hydrogen sulfide and sulfur dioxide react to produce sulfur and water, with the reaction formula being 2H₂S + SO₂ → 3S + 2H₂O. The carbonyl oxygen atom of 2-acetylthiophene and the sulfur atom on the thiophene ring have a certain electron-donating ability, which has a certain catalytic effect on this reaction. 2-Phenylethiophene has a high boiling point of 256℃, is stable, and can better disperse and transport liquid sulfur. After standing, the mixture of 2-acetylthiophene and 2-phenylthiophene easily separates from the liquid sulfur, thus facilitating the separation of elemental sulfur. Compared with the traditional Claus process, this solvent method uses a solvent with a certain catalytic effect as the medium, which is less prone to sulfur blockage problems.

[0008] A preferred embodiment of the solvent method for preparing elemental sulfur from hydrogen sulfide and sulfur dioxide is that the mass ratio of 2-acetylthiophene to 2-phenylthiophene in the mixture is (2~3):1.

[0009] By adopting the above technical solution, the mixture with this ratio achieves a better balance between catalytic efficiency, sulfur carrying capacity, solvothermal stability and economy.

[0010] A preferred embodiment of the solvent-based method for preparing elemental sulfur from hydrogen sulfide and sulfur dioxide is that the disproportionation reaction is carried out in a circulating system, which includes an absorption tower having a bubbling zone and a spraying zone. The bubbling zone is loaded with an immersion solution initially composed of 2-acetylthiophene and 2-phenylthiophene, the temperature of which is 120-150°C. The spraying zone sprays an immersion solution containing 2-acetylthiophene and 2-phenylthiophene as active ingredients, the temperature of which is also 120-150°C.

[0011] Hydrogen sulfide and sulfur dioxide are introduced into the soaking solution to react. Unreacted hydrogen sulfide and sulfur dioxide escape from the soaking solution and enter the spray zone, where they mix with the spray solution and undergo a further neutralization reaction.

[0012] By adopting the above technical solution, and through the absorption tower design that combines the bubbling zone and the spray zone, the gas-liquid mass transfer efficiency and reaction completeness are significantly improved. The bubbling zone provides sufficient contact to ensure the reaction proceeds fully, while the spray zone further purifies the exhaust gas.

[0013] It should be noted that the bubbling zone described above contains an initial soaking solution of 2-acetylthiophene and 2-phenylthiophene because sulfur and water are also generated in the soaking solution as the reaction proceeds, leading to changes in its composition. Similarly, the spraying zone uses a spray solution containing 2-acetylthiophene and 2-phenylthiophene as its active components because, after settling and stratification, the upper layer of liquid in the separation tank primarily consists of 2-acetylthiophene and 2-phenylthiophene, along with water and a small amount of elemental sulfur.

[0014] A preferred embodiment of the solvent method for preparing elemental sulfur from hydrogen sulfide and sulfur dioxide is that the circulation system includes an air blasting disc, a first air inlet pipe, a second air inlet pipe, an exhaust pipe, a spray disc, a first heater, a separation tank, a drain pipe, a circulating liquid pipe, a liquid pump, and a second heater.

[0015] The aeration plate is installed in the bubbling zone, and both the first and second inlet pipes are connected to the aeration plate. Hydrogen sulfide gas enters the soaking liquid sequentially through the first inlet pipe and the aeration plate. Sulfur dioxide gas enters the soaking liquid sequentially through the second inlet pipe and the aeration plate. The exhaust pipe is connected to the gas chamber of the absorption tower. The spray plate is installed in the spray zone. The first heater is installed on the absorption tower to heat the liquid inside the absorption tower to 120~150°C.

[0016] The higher end of the lower drain pipe connects to the bottom of the absorption tower, and the lower end connects to the middle of the separation tank. The inlet end of the circulating liquid pipe connects to the upper part of the separation tank, and the outlet end connects to the spray plate. The liquid pump and the second heater are installed on the circulating liquid pipe. The liquid pump draws liquid from the upper part of the separation tank and passes it through the second heater. The second heater heats the liquid to 120~150°C before it is introduced into the spray plate.

[0017] By adopting the above technical solution, the mixture after the reaction of hydrogen sulfide and sulfur dioxide flows into the separation tank. Sulfur is located in the lower layer of the separation tank, while the mixture of 2-acetylthiophene and 2-phenylthiophene is located in the upper layer, thus regenerating the mixture. A liquid pump draws the upper layer of the 2-acetylthiophene and 2-phenylthiophene mixture, heats it to 120-150°C through a second heater, and then introduces it into the spray plate, allowing the spray liquid to continue promoting the reaction of hydrogen sulfide and sulfur dioxide. This application establishes a continuous cycle process of reaction-separation-regeneration. The solvent carries away the sulfur generated in the reaction zone, and high-purity liquid sulfur product can be separated by simple static sedimentation. The solvent is then heated and reused. This process has a high degree of automation and minimal solvent loss. The gas chamber of the absorption tower is the gas region within the absorption tower, which includes the spray zone.

[0018] A preferred embodiment of the solvent method for preparing elemental sulfur from hydrogen sulfide and sulfur dioxide is that the molar ratio of hydrogen sulfide gas introduced into the absorption tower from the first inlet pipe to sulfur dioxide gas introduced into the absorption tower from the second inlet pipe is (2.05~2.2):1.

[0019] By adopting the above technical solution, the input ratio of hydrogen sulfide and sulfur dioxide is matched with their reaction ratio, resulting in a high reaction conversion rate of hydrogen sulfide and sulfur dioxide and reducing exhaust gas residue.

[0020] A preferred embodiment of the solvent method for preparing elemental sulfur from hydrogen sulfide and sulfur dioxide is as follows: a first flow meter is installed on the first inlet pipe, through which hydrogen sulfide gas at room temperature and pressure is passed; a second flow meter is installed on the second inlet pipe, through which sulfur dioxide gas at room temperature and pressure is passed; a third flow meter is installed on the circulating liquid pipe; the volumetric flow rate of the circulating liquid measured by the third flow meter is 1 to 8 times the sum of the volumetric flow rates of hydrogen sulfide measured by the first flow meter and the volumetric flow rates of sulfur dioxide measured by the second flow meter.

[0021] By adopting the above technical solution, this flow rate range ensures sufficient solvent to absorb and react with the gas, resulting in good mass transfer and reaction driving force. It should be noted that ambient temperature and pressure can be 20±5℃ and 101.325±2kPa.

[0022] A preferred embodiment of the solvent method for preparing elemental sulfur from hydrogen sulfide and sulfur dioxide is as follows: after turning on the liquid pump and stabilizing the liquid circulation, the distance from the aeration plate to the surface of the soaking liquid is 1.5~2m.

[0023] By adopting the above technical solution, the residence time of the mixed bubbles of hydrogen sulfide and sulfur dioxide in the soaking solution is about 5 to 8 seconds, which is sufficient for most of the hydrogen sulfide and sulfur dioxide to react and generate sulfur and water.

[0024] A preferred embodiment of the solvent method for preparing elemental sulfur from hydrogen sulfide and sulfur dioxide is as follows: the circulation system includes a condenser installed on the exhaust pipe; the exhaust gas is condensed to obtain condensate and non-condensable gas; the non-condensable gas is sent to a combustion furnace for treatment; after the condensate separates into layers, the lower organic phase is returned to the separation tank, and the upper aqueous phase is sent to a wastewater tank for treatment.

[0025] By adopting the above technical solution, the organic phase is a mixture of 2-acetylthiophene and 2-phenylthiophene. The non-condensable gas contains trace amounts of unreacted hydrogen sulfide and sulfur dioxide. After appropriate treatment, materials are saved and pollutant emissions are reduced.

[0026] In summary, the solvent-based method for preparing elemental sulfur from hydrogen sulfide and sulfur dioxide in this application has the following beneficial effects: Using a mixture of liquid 2-acetylthiophene and 2-phenylthiophene as the reaction medium, hydrogen sulfide and sulfur dioxide react to produce sulfur and water. The carbonyl oxygen atom of 2-acetylthiophene and the sulfur atom on the thiophene ring have a certain electron-donating ability, thus catalyzing the reaction. 2-Acetylthiophene lowers the reaction energy barrier and improves the reaction efficiency by activating sulfur atoms or reaction intermediates. 2-Phenylethiophene has a high boiling point of 256℃ and is stable. At temperatures of 120~150℃, both sulfur and the solvent exhibit good fluidity at high temperatures. Combined with the strong turbulence in the solvent, the liquid sulfur is dispersed into tiny droplets, forming a homogeneous, pumpable high-temperature slurry with the solvent. The slurry after the reaction enters a separation tank. Once the slurry returns to calm, due to the immiscibility of molten sulfur and the organic solvent, and the density difference, the tiny sulfur droplets quickly aggregate and sink to the bottom, making it easy to separate elemental sulfur. Compared to the traditional Claus process, the solvent method in this scheme uses a solvent with certain catalytic properties as the reaction medium, which makes the production process less prone to sulfur blockage and improves production efficiency. Attached Figure Description

[0027] Figure 1 This is a schematic diagram of the loop system structure of this application.

[0028] Reference numerals in the attached diagram: 1. Absorption tower; 2. Blowing plate; 3. First inlet pipe; 4. Second inlet pipe; 5. Spray plate; 6. First heater; 7. Separation tank; 8. Down drain pipe; 9. Circulating liquid pipe; 10. Liquid pump; 11. Second heater; 12. Exhaust pipe; 13. Condenser; 101. Bubbling zone; 102. Spray zone; 14. First flow meter; 15. Second flow meter; 16. Third flow meter; 17. Collection pipe; 18. Valve; 19. Product tank. Detailed Implementation

[0029] The technical solutions in the embodiments are described clearly and completely below. Obviously, the described embodiments are only a part of the embodiments of this application, and not all of the embodiments. Based on the following embodiments, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of this application. Example 1

[0030] Elemental sulfur is prepared from hydrogen sulfide and sulfur dioxide using a solvent method. Hydrogen sulfide and sulfur dioxide are passed into a mixture of 2-acetylthiophene and 2-phenylthiophene to undergo a disproportionation reaction. Hydrogen sulfide and sulfur dioxide react to produce sulfur and water, with the reaction equation 2H₂S + SO₂ → 3S + 2H₂O. This reaction is carried out in a circulating system, as detailed below.

[0031] refer to Figure 1The circulation system includes an absorption tower 1, an air blasting plate 2, a first air inlet pipe 3, a second air inlet pipe 4, a spray plate 5, a first heater 6, a separation tank 7, a drain pipe 8, a circulating liquid pipe 9, a liquid pump 10, a second heater 11, an exhaust pipe 12, and a condenser 13.

[0032] The absorber tower 1 has a lower bubbling zone 101 and an upper spraying zone 102. The bubbling zone 101 is filled with 1 t of immersion solution containing 2-acetylthiophene and 2-phenylthiophene in a mass ratio of 2:1. A first heater 6 is installed on the absorber tower 1 to heat the immersion solution in the absorber tower 1 to 125±5℃ and to maintain the spraying solution in the absorber tower 1 at 125±5℃.

[0033] The bubbling plate 2 is installed in the bubbling zone 101, and both the first inlet pipe 3 and the second inlet pipe 4 are connected to the bubbling plate 2. Hydrogen sulfide gas enters the soaking solution sequentially through the first inlet pipe 3 and the bubbling plate 2. Sulfur dioxide gas enters the soaking solution sequentially through the second inlet pipe 4 and the bubbling plate 2. The temperature of the hydrogen sulfide gas entering the absorption tower 1 from the first inlet pipe 3 and the temperature of the sulfur dioxide gas entering the absorption tower 1 from the second inlet pipe 4 are both 20°C, the pressure is both 101 kPa, and the molar concentration of hydrogen sulfide and sulfur dioxide is both 41.44 mol / m³. 3 A first flow meter 14 is installed on the first intake pipe 3, and a second flow meter 15 is installed on the second intake pipe 4. The hydrogen sulfide gas flow rate is 20.5 m³ / s. 3 / h, sulfur dioxide gas flow rate 10m 3 / h, meaning the hydrogen sulfide gas flow rate is 2.05 times the sulfur dioxide gas flow rate, thus the molar ratio of hydrogen sulfide to sulfur dioxide is 2.05:1. Hydrogen sulfide and sulfur dioxide will react in the immersion solution to produce elemental sulfur and water.

[0034] A spray plate 5 is installed in the spray zone 102. The higher end of the lower drain pipe 8 connects to the bottom of the absorption tower 1, and the lower end connects to the middle of the separation tank 7, allowing the reacted liquid sulfur to automatically flow into the separation tank 7. In the separation tank 7, 2-acetylthiophene and 2-phenylthiophene float to the top, while the liquid sulfur sinks to the bottom. The inlet end of the external circulating liquid pipe 9 connects to the top of the separation tank 7, and the outlet end connects to the spray plate 5. A liquid pump 10 and a second heater 11 are installed on the circulating liquid pipe 9. The liquid pump 10 draws liquid from the upper part of the separation tank 7 and passes it through the second heater 11. The second heater 11 heats the liquid to 125±5℃ before introducing it into the spray plate 5. The spray plate 5 sprays a solution at a temperature of 125±5℃ containing 2-acetylthiophene and 2-phenylthiophene to further react the hydrogen sulfide and sulfur dioxide that have escaped from the soaking solution. After the liquid pump 10 is turned on and circulation stabilizes, the distance from the air vent plate 2 to the surface of the soaking liquid is 1.5m. A third flow meter 16 is installed on the circulating liquid pipe 9. The volumetric flow rate of the circulating liquid measured by the third flow meter 16 is 1 times the sum of the volumetric flow rates of hydrogen sulfide measured by the first flow meter 14 and sulfur dioxide measured by the second flow meter 15.

[0035] Exhaust pipe 12 is connected to the top of absorption tower 1, and condenser 13 is installed on exhaust pipe 12. The exhaust gas discharged from absorption tower 1 is condensed by condenser 13 to obtain condensate and non-condensable gas. The non-condensable gas is sent to the incinerator for treatment. After the condensate separates into layers, the lower organic phase is returned to separation tank 7, and the upper aqueous phase is sent to the wastewater tank for treatment.

[0036] The circulation system also includes a collection pipe 17, a valve 18, and a product tank 19. The product tank 19 is located below the separation tank 7, and the two ends of the collection pipe 17 are connected to the bottom of the separation tank 7 and the top of the product tank 19, respectively. The valve 18 is installed on the collection pipe 17.

[0037] After the reaction, the liquid pump 10 is turned off to stop the circulation, so that the liquid in the separation tank 7 can be better separated into layers. In the separation tank 7, 2-acetylthiophene and 2-phenylthiophene float to the top of the separation tank 7, while liquid sulfur sinks to the bottom of the separation tank 7. The valve 18 is opened, and the liquid sulfur in the lower layer of the separation tank 7 flows downward into the product tank 19. After collection, the valve 18 is closed.

[0038] The sulfur yield is calculated as follows: Sulfur yield = molar amount of sulfur ÷ (molar amount of sulfur dioxide × 3) × 100%.

[0039] After 1 hour of reaction, 80.971 kg of sulfur was collected and purified to a purity of over 99.9 wt%, resulting in a calculated sulfur molar amount of 2525.61 mol. The molar amount of sulfur dioxide added was 41.44 mol / m³. 3 ×20.5m 3 / h×1h=849.52mol. The calculated sulfur yield after 1h of cycling is 99.10%.

[0040] After 10 hours of reaction, 808.407 kg of sulfur was collected and purified to a purity of over 99.9 wt%, yielding a calculated sulfur molar amount of 25215.44 mol. The molar amount of sulfur dioxide added was 41.44 mol / m³. 3 ×20.5m 3 / h×10h=8495.2mol. The calculated sulfur yield after 1h of cycling is 98.94%. Example 2

[0041] Elemental sulfur is prepared from hydrogen sulfide and sulfur dioxide using a solvent method. Hydrogen sulfide and sulfur dioxide are passed into a mixture of 2-acetylthiophene and 2-phenylthiophene to undergo a disproportionation reaction. Hydrogen sulfide and sulfur dioxide react to produce sulfur and water, with the reaction equation 2H₂S + SO₂ → 3S + 2H₂O. This reaction is carried out in a circulating system, as detailed below.

[0042] The circulation system includes an absorption tower 1, an air blasting plate 2, a first air inlet pipe 3, a second air inlet pipe 4, a spray plate 5, a first heater 6, a separation tank 7, a drain pipe 8, a circulating liquid pipe 9, a liquid pump 10, a second heater 11, an exhaust pipe 12, and a condenser 13.

[0043] The absorber tower 1 has a lower bubbling zone 101 and an upper spraying zone 102. The bubbling zone 101 is filled with 1 ton of immersion solution containing 2-acetylthiophene and 2-phenylthiophene in a mass ratio of 2.5:1. A first heater 6 is installed on the absorber tower 1 to heat the immersion solution in the absorber tower 1 to 135±5°C and to maintain the spraying solution in the absorber tower 1 at 135±5°C.

[0044] The bubbling plate 2 is installed in the bubbling zone 101, and both the first inlet pipe 3 and the second inlet pipe 4 are connected to the bubbling plate 2. Hydrogen sulfide gas enters the soaking solution sequentially through the first inlet pipe 3 and the bubbling plate 2. Sulfur dioxide gas enters the soaking solution sequentially through the second inlet pipe 4 and the bubbling plate 2. The temperature of the hydrogen sulfide gas entering the absorption tower 1 from the first inlet pipe 3 and the temperature of the sulfur dioxide gas entering the absorption tower 1 from the second inlet pipe 4 are both 20°C, the pressure is both 101 kPa, and the molar concentration of hydrogen sulfide and sulfur dioxide is both 41.44 mol / m³. 3 A first flow meter 14 is installed on the first intake pipe 3, and a second flow meter 15 is installed on the second intake pipe 4. The hydrogen sulfide gas flow rate is 21 m³ / s. 3 / h, sulfur dioxide gas flow rate 10m 3 / h, meaning the hydrogen sulfide gas flow rate is 2.1 times the sulfur dioxide gas flow rate, which gives a molar ratio of hydrogen sulfide to sulfur dioxide of 2.1:1. Hydrogen sulfide and sulfur dioxide will react in the immersion solution to produce elemental sulfur and water.

[0045] A spray plate 5 is installed in the spray zone 102. The higher end of the lower drain pipe 8 connects to the bottom of the absorption tower 1, and the lower end connects to the middle of the separation tank 7, allowing the reacted liquid sulfur to automatically flow into the separation tank 7. In the separation tank 7, 2-acetylthiophene and 2-phenylthiophene float to the top, while the liquid sulfur sinks to the bottom. The inlet end of the external circulating liquid pipe 9 connects to the top of the separation tank 7, and the outlet end connects to the spray plate 5. A liquid pump 10 and a second heater 11 are installed on the circulating liquid pipe 9. The liquid pump 10 draws liquid from the upper part of the separation tank 7 and passes it through the second heater 11. The second heater 11 heats the liquid to 135±5℃ before introducing it into the spray plate 5. The spray plate 5 sprays a solution at a temperature of 135±5℃ containing 2-acetylthiophene and 2-phenylthiophene to further react the hydrogen sulfide and sulfur dioxide that have escaped from the soaking solution. After the liquid pump 10 is turned on and circulation stabilizes, the distance from the air vent plate 2 to the surface of the soaking liquid is 1.8m. A third flow meter 16 is installed on the circulating liquid pipe 9. The volumetric flow rate of the circulating liquid measured by the third flow meter 16 is 4 times the sum of the volumetric flow rates of hydrogen sulfide measured by the first flow meter 14 and sulfur dioxide measured by the second flow meter 15.

[0046] Exhaust pipe 12 is connected to the top of absorption tower 1, and condenser 13 is installed on exhaust pipe 12. The exhaust gas discharged from absorption tower 1 is condensed by condenser 13 to obtain condensate and non-condensable gas. The non-condensable gas is sent to the incinerator for treatment. After the condensate separates into layers, the lower organic phase is returned to separation tank 7, and the upper aqueous phase is sent to the wastewater tank for treatment.

[0047] The circulation system also includes a collection pipe 17, a valve 18, and a product tank 19. The product tank 19 is located below the separation tank 7, and the two ends of the collection pipe 17 are connected to the bottom of the separation tank 7 and the top of the product tank 19, respectively. The valve 18 is installed on the collection pipe 17.

[0048] After the reaction, the liquid pump 10 is turned off to stop the circulation, so that the liquid in the separation tank 7 can be better separated into layers. In the separation tank 7, 2-acetylthiophene and 2-phenylthiophene float to the top of the separation tank 7, while liquid sulfur sinks to the bottom of the separation tank 7. The valve 18 is opened, and the liquid sulfur in the lower layer of the separation tank 7 flows downward into the product tank 19. After collection, the valve 18 is closed.

[0049] The sulfur yield is calculated as follows: Sulfur yield = molar amount of sulfur ÷ (molar amount of sulfur dioxide × 3) × 100%.

[0050] After 1 hour of reaction, 83.005 kg of sulfur was collected and purified to a purity of over 99.9 wt%, resulting in a calculated sulfur molar amount of 2589.05 mol. The molar amount of sulfur dioxide added was 41.44 mol / m³. 3 ×21m 3 / h×1h=870.24mol. The calculated sulfur yield after 1h of cycling is 99.17%.

[0051] After 10 hours of reaction, 828.375 kg of sulfur was collected and purified to a purity of over 99.9 wt%, resulting in a calculated sulfur molar amount of 25838.27 mol. The molar amount of sulfur dioxide added was 41.44 mol / m³. 3 ×21m 3 / h×10h=8702.4mol. The calculated sulfur yield after 1 hour of cycling is 98.97%. Example 3

[0052] Elemental sulfur is prepared from hydrogen sulfide and sulfur dioxide using a solvent method. Hydrogen sulfide and sulfur dioxide are passed into a mixture of 2-acetylthiophene and 2-phenylthiophene to undergo a disproportionation reaction. Hydrogen sulfide and sulfur dioxide react to produce sulfur and water, with the reaction equation 2H₂S + SO₂ → 3S + 2H₂O. This reaction is carried out in a circulating system, as detailed below.

[0053] The circulation system includes an absorption tower 1, an air blasting plate 2, a first air inlet pipe 3, a second air inlet pipe 4, a spray plate 5, a first heater 6, a separation tank 7, a drain pipe 8, a circulating liquid pipe 9, a liquid pump 10, a second heater 11, an exhaust pipe 12, and a condenser 13.

[0054] The absorber tower 1 has a lower bubbling zone 101 and an upper spraying zone 102. The bubbling zone 101 is filled with 1 t of immersion solution containing 2-acetylthiophene and 2-phenylthiophene in a mass ratio of 3:1. A first heater 6 is installed on the absorber tower 1 to heat the immersion solution in the absorber tower 1 to 145±5℃ and to maintain the spraying solution in the absorber tower 1 at 145±5℃.

[0055] The bubbling plate 2 is installed in the bubbling zone 101, and both the first inlet pipe 3 and the second inlet pipe 4 are connected to the bubbling plate 2. Hydrogen sulfide gas enters the soaking solution sequentially through the first inlet pipe 3 and the bubbling plate 2. Sulfur dioxide gas enters the soaking solution sequentially through the second inlet pipe 4 and the bubbling plate 2. The temperature of the hydrogen sulfide gas entering the absorption tower 1 from the first inlet pipe 3 and the temperature of the sulfur dioxide gas entering the absorption tower 1 from the second inlet pipe 4 are both 20°C, the pressure is both 101 kPa, and the molar concentration of hydrogen sulfide and sulfur dioxide is both 41.44 mol / m³. 3A first flow meter 14 is installed on the first intake pipe 3, and a second flow meter 15 is installed on the second intake pipe 4. The hydrogen sulfide gas flow rate is 22 m³ / s. 3 / h, sulfur dioxide gas flow rate 10m 3 / h, meaning the hydrogen sulfide gas flow rate is 2.2 times the sulfur dioxide gas flow rate, which gives a molar ratio of hydrogen sulfide to sulfur dioxide of 2.2:1. Hydrogen sulfide and sulfur dioxide will react in the soaking solution to produce elemental sulfur and water.

[0056] A spray plate 5 is installed in the spray zone 102. The higher end of the lower drain pipe 8 connects to the bottom of the absorption tower 1, and the lower end connects to the middle of the separation tank 7, allowing the reacted liquid sulfur to automatically flow into the separation tank 7. In the separation tank 7, 2-acetylthiophene and 2-phenylthiophene float to the top, while the liquid sulfur sinks to the bottom. The inlet end of the external circulating liquid pipe 9 connects to the top of the separation tank 7, and the outlet end connects to the spray plate 5. A liquid pump 10 and a second heater 11 are installed on the circulating liquid pipe 9. The liquid pump 10 draws liquid from the upper part of the separation tank 7 and passes it through the second heater 11. The second heater 11 heats the liquid to 145±5℃ before introducing it into the spray plate 5. The spray plate 5 sprays a solution at a temperature of 145±5℃ containing 2-acetylthiophene and 2-phenylthiophene to further react the hydrogen sulfide and sulfur dioxide that have escaped from the soaking solution. After the liquid pump 10 is turned on and circulation stabilizes, the distance from the air vent plate 2 to the surface of the soaking liquid is 2m. A third flow meter 16 is installed on the circulating liquid pipe 9. The volumetric flow rate of the circulating liquid measured by the third flow meter 16 is 8 times the sum of the volumetric flow rates of hydrogen sulfide measured by the first flow meter 14 and sulfur dioxide measured by the second flow meter 15.

[0057] Exhaust pipe 12 is connected to the top of absorption tower 1, and condenser 13 is installed on exhaust pipe 12. The exhaust gas discharged from absorption tower 1 is condensed by condenser 13 to obtain condensate and non-condensable gas. The non-condensable gas is sent to the incinerator for treatment. After the condensate separates into layers, the lower organic phase is returned to separation tank 7, and the upper aqueous phase is sent to the wastewater tank for treatment.

[0058] The circulation system also includes a collection pipe 17, a valve 18, and a product tank 19. The product tank 19 is located below the separation tank 7, and the two ends of the collection pipe 17 are connected to the bottom of the separation tank 7 and the top of the product tank 19, respectively. The valve 18 is installed on the collection pipe 17.

[0059] After the reaction, the liquid pump 10 is turned off to stop the circulation, so that the liquid in the separation tank 7 can be better separated into layers. In the separation tank 7, 2-acetylthiophene and 2-phenylthiophene float to the top of the separation tank 7, while liquid sulfur sinks to the bottom of the separation tank 7. The valve 18 is opened, and the liquid sulfur in the lower layer of the separation tank 7 flows downward into the product tank 19. After collection, the valve 18 is closed.

[0060] The sulfur yield is calculated as follows: Sulfur yield = molar amount of sulfur ÷ (molar amount of sulfur dioxide × 3) × 100%.

[0061] After 1 hour of reaction, 86.975 kg of sulfur was collected and purified to a purity of over 99.9 wt%, yielding a calculated molar amount of 2712.88 mol of sulfur. The molar amount of sulfur dioxide added was 41.44 mol / m³. 3 ×22m 3 / h×1h=911.68mol. The calculated sulfur yield after 1h of cycling is 99.19%.

[0062] After 10 hours of reaction, 867.646 kg of sulfur was collected and purified to a purity of over 99.9 wt%, yielding a calculated sulfur molar amount of 27063.19 mol. The molar amount of sulfur dioxide added was 41.44 mol / m³. 3 ×22m 3 / h×10h=9116.8mol. The calculated sulfur yield after 1h of cycling is 98.95%.

[0063] Comparative Example 1

[0064] The solvent method for preparing elemental sulfur from hydrogen sulfide and sulfur dioxide differs from Example 1 only in that the initial composition of the bubbling zone 101 in this comparative example is changed to 1 t of pure 2-acetylthiophene, which is circulated into the separation tank 7 and sprayed during the reaction process.

[0065] After 1 hour of reaction, the mass of sulfur with a purity of over 99.9 wt% was 77.451 kg, and the calculated molar amount of sulfur was 2415.81 mol. The molar amount of sulfur dioxide added was 41.44 mol / m³. 3 ×20.5m 3 / h×1h=849.52mol. The calculated sulfur yield after 1h of cycling is 94.79%.

[0066] After 10 hours of reaction, 770.168 kg of sulfur was collected and purified to a purity of over 99.9 wt%, yielding a calculated sulfur molar amount of 24022.71 mol. The molar amount of sulfur dioxide added was 41.44 mol / m³. 3 ×20.5m 3 / h×10h=8495.2mol. The calculated sulfur yield after 1h of cycling is 94.26%.

[0067] Comparative Example 2

[0068] The solvent method for preparing elemental sulfur from hydrogen sulfide and sulfur dioxide differs from Example 2 only in that the initial composition of the bubbling zone 101 in this comparative example is changed to 1 t of pure 2-phenylthiophene, which is circulated into the separation tank 7 and sprayed during the reaction process.

[0069] After 1 hour of reaction, the mass of sulfur with a purity of over 99.9 wt% was 76.878 kg, and the calculated molar amount of sulfur was 2397.94 mol. The molar amount of sulfur dioxide added was 41.44 mol / m³. 3 ×21m 3 / h×1h=870.24mol. The calculated sulfur yield after 1h of cycling is 91.85%.

[0070] After 10 hours of reaction, the mass of sulfur purified to a purity of 99.9 wt% or higher was 756.142 kg, with a calculated molar amount of sulfur of 23585.22 mol. The molar amount of sulfur dioxide added was 41.44 mol / m³. 3 ×21m 3 / h×10h=8702.4mol. The calculated sulfur yield after 1h of cycling is 90.34%.

[0071] Comparative Example 3

[0072] The solvent method for preparing elemental sulfur from hydrogen sulfide and sulfur dioxide differs from Example 3 only in that the initial component loaded in the bubbling zone 101 of this comparative example is changed to 1 t of pure indole, which is circulated into the separation tank 7 and sprayed during the reaction process.

[0073] After 1 hour of reaction, 86.747 kg of sulfur was collected and purified to a purity of over 99.9 wt%, yielding a calculated sulfur molar amount of 2705.77 mol. The molar amount of sulfur dioxide added was 41.44 mol / m³. 3 ×22m 3 / h×1h=911.68mol. The calculated sulfur yield after 1h of cycling is 98.93%.

[0074] After 10 hours of reaction, 834.852 kg of sulfur was collected and purified to a purity of over 99.9 wt%, resulting in a calculated sulfur molar amount of 26040.30 mol. The molar amount of sulfur dioxide added was 41.44 mol / m³. 3 ×22m 3 / h×10h=9116.8mol. The calculated sulfur yield after 1h of cycling is 95.21%.

[0075] Comparative Example 4

[0076] The solvent method for preparing elemental sulfur from hydrogen sulfide and sulfur dioxide differs from Example 1 only in that the initial composition of the bubbling zone 101 in this comparative example is changed to 1 t of pure N,N-dimethylformamide (DMF), which is circulated into the separation tank 7 and sprayed during the reaction process.

[0077] After 1 hour of reaction, 79.746 kg of sulfur was collected and purified to a purity of over 99.9 wt%, yielding a calculated sulfur molar amount of 2487.40 mol. The molar amount of sulfur dioxide added was 41.44 mol / m³. 3 ×20.5m 3 / h×1h=849.52mol. The calculated sulfur yield after 1h of cycling is 97.60%.

[0078] After 10 hours of reaction, the mass of sulfur purified to a purity of 99.9 wt% or higher was 753.664 kg, with a calculated sulfur molar amount of 23507.92 mol. The molar amount of sulfur dioxide added was 41.44 mol / m³. 3 ×20.5m 3 / h×10h=8495.2mol. The calculated sulfur yield after 1h of cycling is 92.24%.

[0079] The results from Examples 1-3 and Comparative Examples 1-4 show that the solvent method used in Examples 1-3 to prepare elemental sulfur from hydrogen sulfide and sulfur dioxide, involving the disproportionation reaction of a mixture of 2-acetylthiophene and 2-phenylthiophene at a temperature of 120-150°C and a mass ratio of (2-3):1, yields a high amount of elemental sulfur. This is mainly because the carbonyl oxygen atom of 2-acetylthiophene and the sulfur atom on the thiophene ring have a certain electron-donating ability, which catalyzes the reaction. 2-Phenylethiophene has a high boiling point of 256°C, is stable, and can effectively disperse and transport liquid sulfur. After standing, the mixture of 2-acetylthiophene and 2-phenylthiophene easily separates from the liquid sulfur, thus facilitating the separation of elemental sulfur. Comparative Example 1, using only 2-acetylthiophene, and Comparative Example 2, using only 2-phenylthiophene as the reaction solvent, lacked the role of the other substance, both resulting in a decrease in yield. Comparative Example 3 used indole as the reaction solvent. The heterocyclic nitrogen in indole provides a lone pair of electrons, allowing it to weakly interact with hydrogen sulfide, sulfur dioxide, or reaction intermediates, exhibiting some catalytic activity for the reaction of hydrogen sulfide and sulfur dioxide. However, indole can dissolve a certain amount of the hot water generated in the reaction, leading to water accumulation. As the reaction proceeds, the water content in the circulating liquid increases, causing the reaction efficiency to decrease rapidly, thus significantly reducing the sulfur yield over 10 hours. Comparative Example 4 used DMF as the reaction solvent. The carbonyl oxygen in DMF has a strong electron-donating ability, exhibiting high catalytic activity for the reaction of hydrogen sulfide and sulfur dioxide. However, DMF is miscible with water, and the water generated from the reaction of hydrogen sulfide and sulfur dioxide dissolves in DMF, making it difficult to remove from the system. This causes the reaction equilibrium to shift to the left, inhibiting sulfur formation and resulting in a rapid decrease in the sulfur yield.

[0080] Examples 1-3 and Comparative Examples 1-4 all employed a solvent method to prepare sulfur. Compared to the traditional Claus process, Examples 1-3 and Comparative Examples 1-4, using solvent as the reaction medium, did not experience sulfur blockage, resulting in high production efficiency. The Claus reaction of hydrogen sulfide and sulfur dioxide was achieved under normal pressure using a combination of bubbling and spraying. The generated sulfur is liquid at a reaction temperature of 120-150°C. Liquid sulfur, 2-acetylthiophene, and 2-phenylthiophene are immiscible and easily separate into layers upon settling. The higher density liquid sulfur sits at the bottom, facilitating sulfur recovery. This economical production method yields a high output.

[0081] Although this application has been described in detail with reference to the foregoing embodiments, those skilled in the art can still modify the technical solutions described in the foregoing embodiments or make equivalent substitutions for some of the technical features. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of this application should be included within the protection scope of this application.

Claims

1. A solvent method for preparing elemental sulfur from hydrogen sulfide and sulfur dioxide, characterized in that, Hydrogen sulfide and sulfur dioxide are passed into a mixture of 2-acetylthiophene and 2-phenylthiophene at a temperature of 120-150℃ to carry out a disproportionation reaction, producing elemental sulfur. In the mixture, the mass ratio of 2-acetylthiophene to 2-phenylthiophene is (2~3):1; The disproportionation reaction is carried out in a circulating system, which includes an absorption tower. The absorption tower has a bubbling zone and a spraying zone. The bubbling zone is loaded with an immersion solution whose initial components are 2-acetylthiophene and 2-phenylthiophene, and the temperature of the immersion solution is 120~150°C. The spraying zone sprays an immersion solution whose effective components are 2-acetylthiophene and 2-phenylthiophene, and the temperature of the immersion solution is 120~150°C. Hydrogen sulfide and sulfur dioxide are introduced into the soaking solution to react. Unreacted hydrogen sulfide and sulfur dioxide escape from the soaking solution and enter the spray zone, where they mix with the spray solution and undergo a further neutralization reaction.

2. The solvent method for preparing elemental sulfur from hydrogen sulfide and sulfur dioxide according to claim 1, characterized in that, The circulation system includes an air blower, a first air inlet pipe, a second air inlet pipe, an exhaust pipe, a spray plate, a first heater, a separation tank, a drain pipe, a circulating liquid pipe, a liquid pump, and a second heater. The bleaching plate is installed in the bubbling zone, and both the first and second air inlets are connected to the bleaching plate. Hydrogen sulfide gas enters the soaking liquid sequentially through the first air inlet and the bleaching plate; sulfur dioxide gas enters the soaking liquid sequentially through the second air inlet and the bleaching plate; the exhaust pipe is connected to the gas chamber of the absorption tower; the spray plate is installed in the spraying zone; the first heater is installed on the absorption tower to heat the liquid in the absorption tower to 120~150℃. The higher end of the lower pipe is connected to the bottom of the absorption tower, and the lower end is connected to the middle of the separation tank; the inlet end of the circulating liquid pipe is connected to the upper part of the separation tank, and the outlet end is connected to the spray plate; the liquid pump and the second heater are installed on the circulating liquid pipe, the liquid pump draws the liquid from the upper part of the separation tank and passes it through the second heater, the second heater heats the liquid to 120~150℃ and then introduces it into the spray plate.

3. The solvent method for preparing elemental sulfur from hydrogen sulfide and sulfur dioxide according to claim 2, characterized in that, The molar ratio of hydrogen sulfide gas introduced into the absorption tower through the first inlet pipe to sulfur dioxide gas introduced into the absorption tower through the second inlet pipe is (2.05~2.2):

1.

4. The solvent-based method for preparing elemental sulfur from hydrogen sulfide and sulfur dioxide according to claim 2, characterized in that, A first flow meter is installed on the first inlet pipe, through which hydrogen sulfide gas at room temperature and pressure passes; a second flow meter is installed on the second inlet pipe, through which sulfur dioxide gas at room temperature and pressure passes; a third flow meter is installed on the circulating liquid pipe; the volumetric flow rate of the circulating liquid measured by the third flow meter is 1 to 8 times the sum of the volumetric flow rates of hydrogen sulfide measured by the first flow meter and the volumetric flow rates of sulfur dioxide measured by the second flow meter.

5. The solvent method for preparing elemental sulfur from hydrogen sulfide and sulfur dioxide according to claim 2, characterized in that, After turning on the liquid pump and stabilizing the liquid circulation, the distance from the air-blowing plate to the surface of the soaking liquid is 1.5~2m.

6. The solvent method for preparing elemental sulfur from hydrogen sulfide and sulfur dioxide according to claim 2, characterized in that, The circulation system includes a condenser installed on the exhaust pipe; the exhaust gas is condensed to obtain condensate and non-condensable gas; the non-condensable gas is sent to the incinerator for treatment. After the condensate separates into layers, the lower organic phase is returned to the separation tank, while the upper aqueous phase is sent to the wastewater treatment tank.

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