Preparation method of fibrous catalyst for simultaneously purifying hydrogen sulfide and hydrogen phosphide

Abstract

The invention discloses a preparation method of a fibrous catalyst for simultaneous purification of hydrogen sulfide and phosphine. The prepared fibrous catalyst is composed of a carbon fiber carrier and a surface metal active component. The fibrous catalyst for synchronous removal of hydrogen sulfide and phosphine is prepared through an electrostatic spinning process, a hydrogen peroxide curing process, a metal salt ultrasonic impregnation process and a roasting process. The fibrous catalyst prepared by the method has rich internal pore structures and high-dispersity surface active components, has strong adsorption and catalysis capabilities, realizes synchronous deep removal of H2S and PH3, and also prolongs the service life of the catalyst. The preparation process is simple, and industrial production is easy to realize.

Description

Technical Field

[0001] This invention relates to the field of environmental catalysts and air pollution purification technology, and in particular to a method for preparing a fibrous catalyst that simultaneously purifies hydrogen sulfide and phosphine. Background Technology

[0002] With the continuous advancement of green and sustainable development, the emission of industrial waste gas is subject to increasingly stringent restrictions. H2S and PH3, as major sulfur- and phosphorus-containing impurities, are often found in reducing industrial waste gases, such as the tail gas from calcium carbide furnaces. The emission of H2S and PH3 not only pollutes the atmospheric environment but also has a significant impact on industrial production equipment and human health. Therefore, the deep purification of H2S and PH3 is crucial for achieving compliant emissions and secondary utilization of industrial waste gas.

[0003] Currently, the removal of H2S and PH3 mainly includes absorption, adsorption, and catalytic oxidation. For large gas volumes, catalytic oxidation is the preferred method. However, H2S and PH3 compete with each other during oxidation, reducing the desulfurization and dephosphorization efficiency of the catalyst and its lifespan. Therefore, the simultaneous and efficient removal of H2S and PH3 while extending catalyst lifespan has become a major challenge restricting catalyst development.

[0004] CN112371087A discloses "a method for preparing and applying an activated carbon fiber-based adsorbent for removing hydrogen sulfide, phosphine, arsine, and ammonia." This method involves treating commercial activated carbon fibers with argon plasma technology followed by metal modification with copper nitrate loading. This adsorbent can simultaneously remove H2S, PH3, AsH3, and NH3, achieving a maximum removal efficiency of 100%. However, it primarily relies on adsorption for removal, and the adsorbent has a relatively short lifespan.

[0005] CN109173669B discloses "a method for purifying yellow phosphorus tail gas," which utilizes a mixed slurry of phosphorus mud and water to oxidize and remove H2S, PH3, and HCN. This method can achieve a removal rate of over 95% for H2S and PH3. However, the oxidant O3 is generated from the reaction of O2 with phosphorus mud, and leaked O3 during the reaction process can further impact the environment. This limits its application in large-scale purification of sulfur- and phosphorus-containing waste gases.

[0006] In summary, existing patents address the problems of low removal efficiency and short service life in the simultaneous purification of H2S and PH3 in industrial waste gas by focusing on improving catalyst adsorption performance and the types of oxidants, which is not conducive to industrial production and application. Summary of the Invention

[0007] Therefore, the present invention provides a method for preparing a fibrous catalyst for the simultaneous purification of hydrogen sulfide and phosphine. This catalyst can not only efficiently remove H2S and PH3 simultaneously, but also has a long service life. The preparation process is simple, and the active components are uniformly dispersed on the surface of the fibrous catalyst and are not prone to agglomeration. It can effectively solve the problem of simultaneous purification of H2S and PH3 in industrial waste gas and is suitable for industrial production and application.

[0008] The method for preparing the fibrous catalyst of the present invention includes the following steps: (1) Polyacrylonitrile fiber (PAN) and a second polymer are mixed evenly to form a polymer mixture. The polymer mixture is added to an organic mixed solvent and stirred to dissolve to obtain a mixed solution. The second polymer is one or any of the following: polyvinylpyrrolidone (PVP), polyvinyl alcohol (PVA), polyvinylidene fluoride (PVDF), polymethyl methacrylate (PMMA), and polyacrylamide (PAM) in any proportion. (2) The mixed solution is prepared into a fiber film by electrospinning, and then the fiber film is soaked in hydrogen peroxide solution for curing. After curing, it is taken out and dried. (3) Add the metal salt precursor and sodium citrate to deionized water and mix to dissolve to obtain an impregnation solution; the metal salt precursor is an oxalate of Fe, Cu, Al, Ni, Ce or La; (4) Place the dried fiber membrane in the impregnation solution for ultrasonic impregnation, and then remove the fiber membrane for secondary drying; (5) The fibrous membrane that has been dried twice is placed in a muffle furnace and calcined to obtain the fibrous catalyst.

[0009] Further, in step (1), the mass ratio of the polyacrylonitrile fiber to the second polymer is polyacrylonitrile fiber: second polymer = 2 to 15:1.

[0010] Further, in step (1), the organic mixed solvent is a mixed solvent of N,N-dimethylformamide and anhydrous ethanol, and the mass ratio of N,N-dimethylformamide to anhydrous ethanol is N,N-dimethylformamide: anhydrous ethanol = 5 to 10: 1; the mass ratio of the polymer mixture to the organic mixed solvent is polymer mixture: organic mixed solvent = 1: 10 to 20.

[0011] Furthermore, in step (1), the stirring temperature is room temperature to 55°C, and the stirring time is 30 to 120 minutes.

[0012] Furthermore, in step (2), the mass percentage of the solute in the hydrogen peroxide aqueous solution is 0.1% to 0.5%.

[0013] Further, in step (3), the mass ratio of the metal salt precursor, sodium citrate and deionized water is metal salt precursor: sodium citrate: deionized water = 5~20:0.5~2:100.

[0014] Furthermore, in step (4), the secondary drying temperature is 80-130°C and the drying time is 8-24 hours.

[0015] Furthermore, in step (5), the calcination temperature is 550–750°C and the calcination time is 60–180 min.

[0016] The specific principle of the method described in this invention is as follows: The abundant porous structure on the surface of the fiber catalyst allows H2S and PH3 to be adsorbed onto the catalyst surface first. Then, under the catalytic action of the surface metal active components, oxygen is used to oxidize H2S and PH3 into elemental sulfur (S) and phosphorus (P), as well as sulfur oxides and phosphorus oxides, which then adhere to the catalyst, achieving simultaneous and deep removal of H2S and PH3. The catalyst can achieve 100% H2S and PH3 removal efficiency at relatively low operating temperatures (60~150℃) and atmospheric pressure.

[0017] Compared with the prior art, the present invention has the following advantages: (1) The fibrous catalyst has a rich internal pore structure and high dispersion of active components. In general electrospinning, fiber adhesion and condensation-induced pore blockage are prone to occur in fibers, which affects the integrity of the fibrous structure and the internal pore volume. This invention uses a two-component polymer mixture and an organic mixed solvent to solve this problem. By utilizing the different decomposition temperatures of the two-component polymers, the melting and adhesion of PAN is avoided during the calcination process. By adding anhydrous ethanol to the solvent, the organic solution is rapidly volatilized during electrospinning, reducing adhesion during the spinning process. Traditional impregnation methods cannot effectively control the agglomeration of metal salts on the catalyst. This invention uses hydrogen peroxide for curing, which not only maintains the network structure of the fiber material but also completely removes the solvent residue on the surface of the fiber material. Sodium citrate is used to enhance the repulsive force between metal salt ions, avoiding the agglomeration of metal salts, thereby forming a uniformly dispersed active component on the catalyst surface.

[0018] (2) Simultaneous deep removal of H2S and PH3 and high stability. In the simultaneous purification of H2S and PH3, H2S and PH3 will affect each other's removal efficiency due to competitive adsorption. This invention solves this problem by increasing the internal pore volume and the dispersion of the metal active component. The abundant pore structure inside the fibrous catalyst provides more sites for the adsorption of H2S, PH3 and oxygen molecules, reducing the competitive adsorption of H2S and PH3 on the catalyst surface. The high dispersion of the surface active component provides more catalytic active sites, enhancing the simultaneous removal performance of H2S and PH3. The above characteristics not only achieve simultaneous deep removal of H2S and PH3, but also improve the service life of the catalyst. Attached Figure Description

[0019] Figure 1 This is a scanning electron microscope image of the catalyst prepared in Example 1 of the present invention. Detailed Implementation

[0020] The present invention will be further described below with reference to the embodiments.

[0021] Example 1 Polyacrylonitrile fiber (PAN) and polyvinyl alcohol (PVA) were mixed at a mass ratio of PAN:PVA = 6:1, and then added to a mixed solvent of N,N-dimethylformamide (DMF) and anhydrous ethanol. The mass ratio of DMF to anhydrous ethanol was 7:1, and the mass ratio of the total mass of the PAN+PVA polymer mixture to the organic mixed solvent was 1:10. The mixture was then stirred at room temperature for 120 min to obtain a mixed solution. The mixed solution was used to prepare a fiber film by electrospinning, and then the fiber film was immersed in a 0.3% hydrogen peroxide solution for curing. After curing, it was removed and dried in an oven. Ferric oxalate and sodium citrate were added to deionized water to obtain an impregnation solution. The mass ratio of ferric oxalate to sodium citrate to deionized water was ferric oxalate:sodium citrate:deionized water = 5:2:100. The dried fiber film was ultrasonically impregnated in the impregnation solution, and then the fiber film was removed and dried again in an oven at 110℃ for 8 h. The fibrous membrane, after being dried twice, was placed in a muffle furnace and calcined at 600°C for 100 min to obtain fibrous catalyst A.

[0022] Example 2 Polyacrylonitrile fiber (PAN) and polyvinylidene fluoride (PVDF) were mixed at a mass ratio of PAN:PVDF = 2:1, and then added to a mixed solvent of N,N-dimethylformamide (DMF) and anhydrous ethanol. The mass ratio of DMF to anhydrous ethanol was 8:1, and the mass ratio of the total mass of the PAN + PVDF polymer mixture to the organic mixed solvent was 1:20. The mixture was then stirred at 30°C for 70 min to obtain a mixed solution. The mixed solution was used to prepare a fiber film by electrospinning, and then the fiber film was immersed in a 0.2% hydrogen peroxide solution for curing. After curing, it was removed and dried in an oven. Copper oxalate and sodium citrate were added to deionized water to dissolve and obtain an impregnation solution. The mass ratio of copper oxalate to sodium citrate to deionized water was 14:1.5:100. The dried fiber membrane was ultrasonically impregnated in an impregnation solution, then removed and placed in an oven for secondary drying at 100°C for 14 hours. The secondary-dried fiber membrane was then calcined in a muffle furnace at 750°C for 120 minutes to obtain fibrous catalyst B.

[0023] Example 3 Polyacrylonitrile fiber (PAN) and polyvinylpyrrolidone (PVP) were mixed at a mass ratio of PAN:PVP = 12:1, and then added to a mixed solvent of N,N-dimethylformamide (DMF) and anhydrous ethanol. The mass ratio of DMF to anhydrous ethanol was 9:1, and the mass ratio of the total mass of the PAN + PVP polymer mixture to the organic mixed solvent was 1:14. The mixture was then stirred at 55°C for 50 min to obtain a mixed solution. The mixed solution was used to prepare a fiber film by electrospinning, and then the fiber film was immersed in a 0.5% hydrogen peroxide solution for curing. After curing, it was removed and dried in an oven. Nickel oxalate and sodium citrate were added to deionized water to dissolve and obtain an impregnation solution. The mass ratio of nickel oxalate to sodium citrate to deionized water was 20:1:100. The dried fiber membrane was ultrasonically impregnated in an impregnation solution, then removed and placed in an oven for secondary drying at 80°C for 16 hours. The secondary-dried fiber membrane was then calcined in a muffle furnace at 550°C for 80 minutes to obtain fibrous catalyst C.

[0024] Example 4 Polyacrylonitrile fiber (PAN) and polyacrylamide (PAM) were mixed at a mass ratio of PAN fiber:polyacrylamide = 8:1, and then added to a mixed solvent of N,N-dimethylformamide (DMF) and anhydrous ethanol. The mass ratio of DMF to anhydrous ethanol was 6:1, and the mass ratio of the total mass of the PAN+PAM polymer mixture to the organic mixed solvent was 1:16. The mixture was then stirred at 40°C for 60 min to obtain a mixed solution. The mixed solution was used to prepare a fiber film by electrospinning, and then the fiber film was immersed in a 0.15% hydrogen peroxide solution for curing. After curing, it was removed and dried in an oven. Aluminum oxalate and sodium citrate were added to deionized water and dissolved to obtain an impregnation solution. The mass ratio of aluminum oxalate to sodium citrate to deionized water was 8:0.5:100. The dried fiber membrane was ultrasonically impregnated in an impregnation solution, then removed and placed in an oven for secondary drying at 130°C for 24 hours. The secondary-dried fiber membrane was then calcined in a muffle furnace at 700°C for 60 minutes to obtain fibrous catalyst D.

[0025] Example 5 Polyacrylonitrile fiber (PAN) and polymethyl methacrylate (PMMA) were mixed at a mass ratio of PAN:PMMA = 15:1, and then added to a mixed solvent of N,N-dimethylformamide (DMF) and anhydrous ethanol. The mass ratio of DMF to anhydrous ethanol was 5:1, and the mass ratio of the total mass of the PAN+PMMA polymer mixture to the organic mixed solvent was 1:13. The mixture was then stirred at 35°C for 30 min to obtain a mixed solution. The mixed solution was used to prepare a fiber film by electrospinning, and then the fiber film was immersed in a 0.4% hydrogen peroxide solution for curing. After curing, it was removed and dried in an oven. Cerium oxalate and sodium citrate were added to deionized water to dissolve and obtain an impregnation solution. The mass ratio of cerium oxalate to sodium citrate to deionized water was 11:2:100. The dried fiber membrane was ultrasonically impregnated in an impregnation solution, then removed and placed in an oven for secondary drying at 95°C for 18 hours. The secondary-dried fiber membrane was then calcined in a muffle furnace at 650°C for 180 minutes to obtain fibrous catalyst E.

[0026] Example 6 Polyacrylonitrile fiber (PAN) and polyvinyl alcohol (PVA) were mixed at a mass ratio of PAN fiber:PVA = 5:1, and then added to a mixed solvent of N,N-dimethylformamide (DMF) and anhydrous ethanol. The mass ratio of DMF to anhydrous ethanol was 10:1, and the mass ratio of the total mass of the PAN+PVA polymer mixture to the organic mixed solvent was 1:15. The mixture was then stirred at 45°C for 65 min to obtain a mixed solution. The mixed solution was used to prepare a fiber film by electrospinning, and then the fiber film was immersed in a 0.1% hydrogen peroxide solution for curing. After curing, it was removed and dried in an oven. Lanthanum oxalate and sodium citrate were added to deionized water to dissolve and obtain an impregnation solution. The mass ratio of lanthanum oxalate to sodium citrate to deionized water was 16:1.8:100. The dried fiber membrane was ultrasonically impregnated in an impregnation solution, then removed and placed in an oven for secondary drying at 120°C for 10 hours. The secondary-dried fiber membrane was then calcined in a muffle furnace at 720°C for 150 minutes to obtain fibrous catalyst F.

[0027] Comparative Example 1 (using only a single polymer) Polyacrylonitrile fibers (PAN) were added to a mixed solvent of N,N-dimethylformamide (DMF) and anhydrous ethanol, with a DMF:anhydrous ethanol mass ratio of 8:1 and a PAN:organic mixed solvent mass ratio of 1:20. The mixture was stirred at 50°C for 90 min to obtain a mixed solution. The mixed solution was then electrospun into a fiber film, which was subsequently cured by immersing it in a 0.25% hydrogen peroxide solution. After curing, the film was removed and dried in an oven. Aluminum oxalate and sodium citrate were dissolved in deionized water to obtain an impregnation solution, with an aluminum oxalate:sodium citrate:deionized water mass ratio of 13:1.3:100. The dried fiber film was ultrasonically impregnated in the impregnation solution, then removed and dried a second time at 85°C for 15 h. The second-dried fiber film was then calcined in a muffle furnace at 680°C for 90 min to obtain fibrous catalyst D1.

[0028] Comparative Example 2 (organic solvent without anhydrous ethanol) Polyacrylonitrile fiber (PAN) and polyvinyl alcohol (PVA) were mixed at a mass ratio of PAN:PVA = 9:1 and then added to N,N-dimethylformamide (DMF). The mass ratio of the total PAN+PVA polymer mixture to DMF was PAN:DMF = 1:11. The mixture was then stirred at 45°C for 85 min to obtain a mixed solution. The mixed solution was used to prepare a fiber film using electrospinning. The fiber film was then immersed in a 0.35% hydrogen peroxide solution for curing. After curing, it was removed and dried in an oven. Ferric oxalate and sodium citrate were dissolved in deionized water to obtain an impregnation solution. The mass ratio of ferric oxalate to sodium citrate to deionized water was ferric oxalate:sodium citrate:deionized water = 15:0.8:100. The dried fiber film was ultrasonically impregnated in the impregnation solution, and then removed and dried again in an oven at 105°C for 16 h. The fibrous membrane, after being dried twice, was placed in a muffle furnace and calcined at 700°C for 110 minutes to obtain fibrous catalyst D2.

[0029] Comparative Example 3 (No hydrogen peroxide was used during the curing process) Polyacrylonitrile fiber (PAN) and polyvinylpyrrolidone (PVP) were mixed at a mass ratio of PAN:PVP = 10:1, and then added to a mixed solvent of N,N-dimethylformamide (DMF) and anhydrous ethanol. The mass ratio of DMF to anhydrous ethanol was 6:1, and the mass ratio of the total mass of the PAN + PVP polymer mixture to the organic mixed solvent was 1:18. The mixture was then stirred at 40°C for 40 min to obtain a mixed solution. The mixed solution was used to prepare a fiber film by electrospinning, and then the fiber film was immersed in deionized water for curing. After curing, it was removed and dried in an oven. Cerium oxalate and sodium citrate were added to deionized water to dissolve and obtain an impregnation solution. The mass ratio of cerium oxalate to sodium citrate to deionized water was 6:1:100. The dried fiber film was ultrasonically impregnated in the impregnation solution, and then the fiber film was removed and dried again in an oven at 100°C for 10 h. The fibrous membrane, after being dried twice, was placed in a muffle furnace and calcined at 650°C for 70 minutes to obtain fibrous catalyst D3.

[0030] Comparative Example 4 (No sodium citrate added during the metal impregnation process) Polyacrylonitrile fiber (PAN) and polyacrylamide (PAM) were mixed at a mass ratio of PAN:PAM = 13:1, and then added to a mixed solvent of N,N-dimethylformamide (DMF) and anhydrous ethanol. The mass ratio of DMF to anhydrous ethanol was 5:1, and the mass ratio of the total mass of the PAN+PAM polymer mixture to the organic mixed solvent was 1:15. The mixture was then stirred at 45°C for 100 min to obtain a mixed solution. The mixed solution was used to prepare a fiber film by electrospinning, and then the fiber film was immersed in a 0.2% hydrogen peroxide solution for curing. After curing, it was removed and dried in an oven. Copper oxalate was dissolved in deionized water to obtain an impregnation solution at a mass ratio of copper oxalate:deionized water = 12:100. The dried fiber film was ultrasonically impregnated in the impregnation solution, and then the fiber film was removed and dried again in an oven at 115°C for 12 h. The fibrous membrane, which had been dried twice, was placed in a muffle furnace and calcined at 620°C for 120 min to obtain fibrous catalyst D4.

[0031] The catalyst activity was tested in a fixed-bed quartz reactor under the following conditions: H2S concentration 800 ppm, pH3 concentration 800 ppm, and space velocity 20000 h⁻¹. -1 The reaction temperature was 75℃. The removal efficiency of H2S and PH3 in Examples 1-6 and Comparative Examples 1-4 is shown in Table 1. Service life refers to the reaction time when the catalyst's removal performance is below 95%. The table shows that the desulfurization and dephosphorization performance of the catalysts prepared in Examples 1-6 is far superior to that in Comparative Examples 1-4. Under the above reaction conditions, they can achieve 100% removal efficiency of H2S and PH3, indicating that the catalysts have a significant effect on the simultaneous removal of H2S and PH3.

[0032] Table 1 Desulfurization and dephosphorization performance of catalysts in the examples The technical solutions provided by the present invention have been described in detail above. For those skilled in the art, there will be changes in specific implementation methods and application scope based on the ideas of the embodiments of the present invention. Therefore, the content of this specification should not be construed as a limitation of the present invention.

Claims

1. A method for preparing a fibrous catalyst for the simultaneous purification of hydrogen sulfide and phosphine, characterized in that, Includes the following steps: (1) Polyacrylonitrile fiber (PAN) and a second polymer are mixed evenly to form a polymer mixture. The polymer mixture is added to an organic mixed solvent and stirred to dissolve to obtain a mixed solution. The second polymer is one or any of the following: polyvinylpyrrolidone (PVP), polyvinyl alcohol (PVA), polyvinylidene fluoride (PVDF), polymethyl methacrylate (PMMA), and polyacrylamide (PAM) in any proportion. (2) The mixed solution is prepared into a fiber film by electrospinning, and then the fiber film is soaked in hydrogen peroxide solution for curing. After curing, it is taken out and dried. (3) Add the metal salt precursor and sodium citrate to deionized water and mix to dissolve to obtain an impregnation solution; the metal salt precursor is an oxalate of Fe, Cu, Al, Ni, Ce or La; (4) Place the dried fiber membrane in the impregnation solution for ultrasonic impregnation, and then remove the fiber membrane for secondary drying; (5) The fibrous membrane that has been dried twice is placed in a muffle furnace and calcined to obtain the fibrous catalyst.

2. The method for preparing a fibrous catalyst for simultaneous purification of hydrogen sulfide and phosphine according to claim 1, characterized in that, In step (1), the mass ratio of the polyacrylonitrile fiber to the second polymer is 2 to 15:

1.

3. The method for preparing a fibrous catalyst for simultaneous purification of hydrogen sulfide and phosphine according to claim 1, characterized in that, In step (1), the organic mixed solvent is a mixture of N,N-dimethylformamide and anhydrous ethanol, and the mass ratio of N,N-dimethylformamide to anhydrous ethanol is N,N-dimethylformamide: anhydrous ethanol = 5 to 10: 1; the mass ratio of the polymer mixture to the organic mixed solvent is polymer mixture: organic mixed solvent = 1: 10 to 20.

4. The method for preparing a fibrous catalyst for simultaneous purification of hydrogen sulfide and phosphine according to claim 1, characterized in that, In step (1), the stirring temperature is room temperature to 55°C, and the stirring time is 30 to 120 minutes.

5. The method for preparing a fibrous catalyst for simultaneous purification of hydrogen sulfide and phosphine according to claim 1, characterized in that, In step (2), the mass percentage of the solute in the hydrogen peroxide aqueous solution is 0.1% to 0.5%.

6. The method for preparing a fibrous catalyst for simultaneous purification of hydrogen sulfide and phosphine according to claim 1, characterized in that, In step (3), the mass ratio of the metal salt precursor, sodium citrate and deionized water is metal salt precursor: sodium citrate: deionized water = 5~20:0.5~2:

100.

7. The method for preparing a fibrous catalyst for simultaneous purification of hydrogen sulfide and phosphine according to claim 1, characterized in that, In step (4), the secondary drying temperature is 80-130℃ and the drying time is 8-24h.

8. The method for preparing a fibrous catalyst for simultaneous purification of hydrogen sulfide and phosphine according to claim 1, characterized in that, In step (5), the roasting temperature is 550-750℃ and the roasting time is 60-180min.

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