Porous catalyst as well as preparation method and application thereof
By preparing a porous catalyst, treating slag with dilute hydrochloric acid and dilute acetic acid, and combining hydrothermal reaction and oxygen-enriched roasting, the problems of narrow temperature range and high cost of catalysts in removing SO2 and NOx were solved, and a highly efficient industrial exhaust gas purification effect was achieved.
Patent Information
- Application Number
- CN202512058213.0
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2025-12-31
- Publication Date
- 2026-03-06
AI Technical Summary
Existing catalysts have problems such as narrow reaction temperature range, low efficiency and high cost when removing SO2 and NOx from industrial exhaust gas, especially in complex industrial exhaust gas where simultaneous removal is difficult.
Slag was treated with a mixed solution of dilute hydrochloric acid and dilute acetic acid. A porous catalyst was prepared by hydrothermal reaction and oxygen-enriched roasting. The synergistic effect of chloride ions and acetate ions was used to dissolve sparingly soluble metals in the slag. The internal pore structure was formed by carbon powder template, which improved the specific surface area and reaction activity of the catalyst.
It achieves simultaneous and complete removal of SO2 and NOx from industrial exhaust gas at relatively low temperatures, has a wide operating temperature range and a long service life, the catalyst has a specific surface area of 350~450m2/g, SO2 and NOx removal efficiency reaches 100%, and service life exceeds 130h.
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Abstract
Description
Technical Field
[0001] This invention relates to the field of catalysts, and more particularly to a porous catalyst, its preparation method, and its application. Background Technology
[0002] Industrial waste gas contains large amounts of SO2 and NO. x Not only do they produce unpleasant odors, but they also have certain impacts on the atmospheric environment and human health, such as acid rain corrosion and respiratory diseases. Therefore, SO2 and NO in industrial waste gas... x Deep purification is key to achieving standard emissions and low-carbon emission reduction for industrial waste gas.
[0003] The catalytic reduction method utilizes NH3 to reduce NO x Converted into N2 and H2O, achieving NO x In addition to deep purification, SO2 can also be converted into ammonium sulfate or elemental sulfur for removal during the denitrification process. Traditional SCR catalysts have a narrow reaction temperature range, and the presence of SO2 significantly impacts denitrification efficiency. Therefore, SO2 and NO... x Meanwhile, efficient removal has become a major challenge restricting the development of catalysts.
[0004] A catalyst is provided in the related technology, which uses TiO2 as a support and obtains it by impregnation of metal oxides onto its surface followed by calcination. This catalyst can achieve simultaneous removal of NO and SO2; however, its production cost is high, and it does not address the simultaneous removal of NO2, making it unsuitable for complex industrial exhaust gases containing both SO2 and NO. x Synchronous removal.
[0005] Industrial slag is difficult to treat and dispose of due to the presence of various residual metals. However, these residual metals can help purify sulfur- and nitrogen-containing pollutants in flue gas. Therefore, industrial slag is also used for desulfurization and denitrification. A related technology involves acidifying red mud and biochar separately, then mixing and roasting them to prepare a denitrification catalyst. This catalyst can achieve a NO removal rate of over 90% in the range of 250–400°C; however, it is only suitable for the catalytic removal of NO and is not applicable to SO2 and the complex NO content in industrial exhaust gases. x Simultaneous removal, but the reaction temperature is high and the service life is short. Summary of the Invention
[0006] The purpose of this invention is to provide a porous catalyst, its preparation method, and its application. The porous catalyst prepared by the method provided by this invention can effectively remove SO2 and NO from industrial exhaust gas at relatively low temperatures. x The synchronous and complete removal of the porous catalyst is achieved, and the porous catalyst has a wide operating temperature range and a long service life.
[0007] To achieve the above-mentioned objectives, the present invention provides the following technical solution: This invention provides a method for preparing a porous catalyst, comprising the following steps: (1) After mixing the slag with the acid solution for the first time, filter the solution to obtain a metal ion filtrate; the acid solution is a mixture of dilute hydrochloric acid and dilute acetic acid. (2) The metal ion filtrate obtained in step (1) is mixed with an oxidant for a second time to obtain a high-valence metal ion solution; (3) The high-valence metal ion solution, precipitant and carbon powder obtained in step (2) are mixed and subjected to hydrothermal reaction to obtain catalyst precursor; (4) The catalyst precursor obtained in step (3) is subjected to oxygen-enriched calcination to obtain a porous catalyst.
[0008] Preferably, in step (1), the concentration of dilute hydrochloric acid is 5-10 wt%, and the concentration of dilute acetic acid is 5-8 wt%. The mass ratio of the dilute hydrochloric acid to the dilute acetic acid is (10~20):1.
[0009] Preferably, in step (2), the mass ratio of the metal ion filtrate to the oxidant is 1:(3~8).
[0010] Preferably, the oxidant in step (2) is a hydrogen peroxide solution or a sodium hypochlorite solution; The concentration of the hydrogen peroxide solution or sodium hypochlorite solution is independently 0.5 to 3 wt%.
[0011] Preferably, in step (3), the mass ratio of the high-valence metal ion solution, the precipitant, and the carbon powder is (10~20):(2~5):1.
[0012] Preferably, the precipitant in step (3) is a sodium hydroxide solution or ammonia water; The concentration of the sodium hydroxide solution or ammonia water is independently 0.1~0.5wt%.
[0013] Preferably, the temperature of the hydrothermal reaction in step (3) is 75~130℃ and the time of the hydrothermal reaction is 12~48h.
[0014] Preferably, the oxygen-enriched roasting temperature in step (4) is 500~900℃ and the oxygen-enriched roasting time is 1~5h.
[0015] The present invention also provides a porous catalyst prepared by the preparation method described in the above technical solution.
[0016] This invention also provides the application of the porous catalyst described in the above technical solution in industrial waste gas desulfurization and denitrification.
[0017] This invention provides a method for preparing a porous catalyst, comprising the following steps: (1) mixing slag with an acid solution for the first time and filtering to obtain a metal ion filtrate; the acid solution is a mixture of dilute hydrochloric acid and dilute acetic acid; (2) mixing the metal ion filtrate obtained in step (1) with an oxidant for the second time to obtain a high-valence metal ion solution; (3) mixing the high-valence metal ion solution obtained in step (2), a precipitant, and carbon powder for the third time and performing a hydrothermal reaction to obtain a catalyst precursor; (4) calcining the catalyst precursor obtained in step (3) with oxygen to obtain a porous catalyst. This invention utilizes a mixed solution of dilute hydrochloric acid and dilute acetic acid to treat slag, leveraging the synergistic effect of chloride and acetate ions to achieve one-step dissolution of sparingly soluble metals from the slag and increase the specific surface area of the catalyst. Adding an oxidant to the metal ion filtrate obtained by mixing the slag with the acid solution yields high-valence metal ions, which is beneficial for the in-situ growth of metal oxides and crystal nucleation during the hydrothermal reaction, further increasing the specific surface area of the catalyst. By using carbon powder as a template agent, metal salts can be coated and grown on the carbon powder surface during the hydrothermal reaction. The coated carbon powder is then removed through oxygen-enriched calcination, enriching the internal pore structure of the catalyst, facilitating the migration of gas molecules within the pores, increasing the effective reactive sites of the catalyst, and thus achieving the dissolution of SO2 and NO. x Simultaneously, it removes and improves the catalyst's lifespan and broadens the catalyst's reaction temperature range. Example results show that the porous catalyst prepared by the method provided in this invention has an operating temperature of 160~450℃, and effectively removes SO2 and NO. x The removal efficiency reaches 100%, the service life can reach more than 130 hours, and it has higher SO2 and NO removal efficiency. x It boasts high removal efficiency, a wide operating temperature range, and a long service life, enabling simultaneous desulfurization and denitrification at relatively low reaction temperatures. Attached Figure Description
[0018] Figure 1 This is a SEM image of the porous catalyst prepared in Example 1 of the present invention. Detailed Implementation
[0019] This invention provides a method for preparing a porous catalyst, comprising the following steps: (1) After the slag and acid solution are mixed for the first time, the mixture is filtered to obtain a metal ion filtrate; (2) The metal ion filtrate obtained in step (1) is mixed with an oxidant for a second time to obtain a high-valence metal ion solution; (3) The high-valence metal ion solution, precipitant and carbon powder obtained in step (2) are mixed and subjected to hydrothermal reaction to obtain catalyst precursor; (4) The catalyst precursor obtained in step (3) is subjected to oxygen-enriched calcination to obtain a porous catalyst.
[0020] The present invention involves first mixing slag with an acid solution and then filtering the mixture to obtain a metal ion filtrate.
[0021] In one embodiment of the present invention, the slag is industrial slag; the industrial slag can be copper slag, iron slag, manganese slag, zinc slag, or aluminum slag. The present invention limits the type of slag to those within the above-mentioned range that can utilize the metal ions within the slag to achieve the reuse of industrial slag and solve the problem of harmless treatment of industrial slag.
[0022] In one embodiment of the present invention, the acid solution is a mixed solution of dilute hydrochloric acid and dilute acetic acid; the concentration of the dilute hydrochloric acid can be 5~10wt%; the concentration of the dilute acetic acid can be 5~8wt%; the mass ratio of the dilute hydrochloric acid to the dilute acetic acid can be (10~20):1, (12~18):1, or (15~17):1.
[0023] In one embodiment of the present invention, the mass ratio of the slag to the acid solution can be 1:(5~10), 1:(6~9), or 1:(7~8). By limiting the type and concentration of the acid solution and the ratio of slag to the acid solution to the above ranges, the present invention can utilize the synergistic effect of chloride and acetate ions in dilute hydrochloric acid and dilute acetic acid to achieve one-step dissolution of sparingly soluble metals in the slag, ensuring that the metal residue in the slag after acid dissolution meets the harmless standard and can be disposed of as ordinary solid waste.
[0024] In one embodiment of the present invention, the first mixing can be carried out under stirring conditions. The present invention does not impose a particular limitation on the stirring speed; stirring speeds commonly used by those skilled in the art can be employed.
[0025] In one embodiment of the present invention, the temperature of the first mixing can be 50~85℃, 55~80℃, 60~75℃, or 65~70℃; the time of the first mixing can be 1~5h, 2~4h, or 3~4h. Limiting the temperature and time of the first mixing to the above ranges ensures better dissolution of sparingly soluble metals in the slag.
[0026] This invention does not impose any special limitations on the equipment and operation used for filtration; solid-liquid separation can be achieved using filtration equipment and operation commonly used by those skilled in the art. As one embodiment of this invention, the solid obtained from filtration can be disposed of as ordinary solid waste.
[0027] After obtaining the metal ion filtrate, the present invention performs a second mixing of the metal ion filtrate with an oxidant to obtain a high-valence metal ion solution.
[0028] In one embodiment of the present invention, the oxidant can be a hydrogen peroxide solution or a sodium hypochlorite solution; the concentration of the hydrogen peroxide solution or sodium hypochlorite solution can be independently 0.5~3wt%, 1~2.5wt%, or 1.5~2wt%. In another embodiment of the present invention, the mass ratio of the metal ion filtrate to the oxidant can be 1:(3~8), 1:(4~7), or 1:(4~6). By limiting the type and concentration of the oxidant and the mass ratio of the metal ion filtrate to the oxidant to the above ranges, the present invention can sufficiently oxidize the metal ions in the metal ion filtrate to a high valence state, which is beneficial to the in-situ growth of metal oxides and the formation of crystal nuclei in the subsequent hydrothermal reaction.
[0029] In one embodiment of the present invention, the second mixing can be carried out under stirring conditions. The present invention does not impose a particular limitation on the stirring speed; stirring speeds commonly used by those skilled in the art can be employed.
[0030] In one embodiment of the present invention, the temperature of the second mixing can be 25~50℃, 30~45℃, or 35~40℃; the time of the second mixing can be 2~12h, 4~10h, or 5~8h. Limiting the temperature and time of the second mixing within the above ranges ensures sufficient oxidation of the metal ions.
[0031] After obtaining the high-valence metal ion solution, the present invention mixes the high-valence metal ion solution, precipitant and carbon powder in a third mixture and then carries out a hydrothermal reaction to obtain a catalyst precursor.
[0032] In one embodiment of the present invention, the precipitant may be a sodium hydroxide solution or ammonia; the concentration of the sodium hydroxide solution or ammonia may be 0.1~0.5wt%, 0.2~0.45wt%, 0.25~0.40wt%, or 0.3~0.35wt%.
[0033] In one embodiment of the present invention, the carbon powder can be nano-carbon powder. The present invention does not specifically limit the particle size of the nano-carbon powder, as long as the particle size is within the nanometer range. The use of carbon powder in the present invention lays a good foundation for the subsequent formation of pores within the catalyst.
[0034] In one embodiment of the present invention, the mass ratio of the high-valence metal ion solution, the precipitant, and the carbon powder can be (10~20):(2~5):1, (13~18):(2.5~4.5):1, (14~16):(3~4):1, or (14~15):(3.5~4):1. By limiting the type of precipitant, the size of the carbon powder, and the mass ratio of the high-valence metal ion solution, the precipitant, and the carbon powder to the above ranges, the present invention ensures the complete conduction of the hydrothermal reaction.
[0035] The present invention does not have any particular limitation on the third mixing method, as long as the high-valence metal ion solution, precipitant and carbon powder are mixed.
[0036] In one embodiment of the present invention, the hydrothermal reaction can be carried out in a reaction vessel; the temperature of the hydrothermal reaction can be 75~130℃, 90~120℃, 95~110℃, or 100~105℃; the time of the hydrothermal reaction can be 12~48h, 15~36h, 20~30h, or 22~25h. Limiting the temperature and time of the hydrothermal reaction to the above ranges allows the hydrothermal reaction to proceed smoothly and ensures that the metal oxides on the surface of the carbon powder have a good crystal structure.
[0037] As one embodiment of the present invention, after the hydrothermal reaction is completed, the hydrothermal reaction products are further filtered.
[0038] The present invention does not impose any special limitations on the equipment and operation used for filtration; solid-liquid separation can be achieved by using filtration equipment and operation commonly used by those skilled in the art.
[0039] In one embodiment of the present invention, after filtration, the solid obtained by filtration can be washed and dried in sequence to obtain a catalyst precursor.
[0040] In one embodiment of the present invention, the detergent used for washing can be purified water. The present invention does not specifically limit the number of washes or the washing time, as long as the solids are effectively cleaned.
[0041] The present invention does not impose any special limitations on the equipment and parameter settings used for drying; drying can be achieved using drying equipment and parameters commonly used by those skilled in the art.
[0042] After obtaining the catalyst precursor, the present invention performs oxygen-enriched calcination on the catalyst precursor to obtain a porous catalyst.
[0043] In one embodiment of the present invention, the atmosphere for oxygen-enriched calcination can be a mixture of air and oxygen; the volume ratio of air to oxygen can be 1:(0.5~3), 1:(1~2.5), or 1:(1.5~2); the temperature for oxygen-enriched calcination can be 500~900℃, 600~850℃, 650~800℃, or 700~750℃; and the time for oxygen-enriched calcination can be 1~5h, 2~4h, or 2.5~3h. By limiting the atmosphere, temperature, and time of oxygen-enriched calcination to the above ranges, the present invention ensures the complete decomposition of carbon powder in the porous catalyst, forming more pore structures, thereby giving the catalyst more effective reactive sites, thus achieving SO2 and NO... x At the same time, it removes and improves the service life of the catalyst and widens the reaction temperature range of the catalyst.
[0044] This invention utilizes a mixed solution of dilute hydrochloric acid and dilute acetic acid to treat slag, leveraging the synergistic effect of chloride and acetate ions to achieve one-step dissolution of sparingly soluble metals from the slag and increase the specific surface area of the catalyst. Adding an oxidant to the metal ion filtrate obtained by mixing the slag with the acid solution allows for oxidation, yielding high-valence metal ions. This promotes in-situ growth of metal oxides and crystal nucleation during the hydrothermal reaction, further increasing the catalyst's specific surface area. By using carbon powder as a template, metal salts can be coated and grown on the carbon powder surface during the hydrothermal reaction. Oxygen-enriched calcination removes the coated carbon powder, enriching the catalyst's internal pore structure, facilitating gas molecule migration within the pores, and increasing the effective reactive sites of the catalyst, thereby achieving the dissolution of SO2 and NO. x At the same time, it removes and improves the service life of the catalyst and widens the reaction temperature range of the catalyst.
[0045] This invention also provides a porous catalyst prepared by the preparation method described above; the specific surface area of the porous catalyst can be 350~450 m². 2 / g.
[0046] This invention also provides the application of the porous catalyst described in the above technical solution in industrial waste gas desulfurization and denitrification.
[0047] The technical solutions of this invention will be clearly and completely described below with reference to the embodiments thereof. Obviously, the described embodiments are only a part of the embodiments of this invention, and not all of them. All other embodiments obtained by those skilled in the art based on the embodiments of this invention without creative effort are within the scope of protection of this invention.
[0048] Example 1 A method for preparing a porous catalyst comprises the following steps: (1) Copper slag and acid solution (a mixed solution of 5wt% dilute hydrochloric acid and 5wt% dilute acetic acid, with a mass ratio of 20:1) were heated and stirred at 55°C for 2 hours at a mass ratio of 1:9 to obtain metal ion filtrate. (2) The metal ion filtrate obtained in step (1) is mixed with an oxidant (0.5wt% hydrogen peroxide solution) at a mass ratio of 1:6 at 50°C and stirred for 10 hours to obtain a high-valence metal ion solution. (3) The high-valence metal ion solution, precipitant (0.5wt% sodium hydroxide solution) and nano carbon powder obtained in step (2) are mixed in a mass ratio of 14:5:1 and then subjected to hydrothermal reaction at 75°C for 48h in a reactor. The hydrothermal reaction product is then filtered and rinsed 5 times with pure water, and then dried at 105°C for 10h to obtain the catalyst precursor. (4) The catalyst precursor obtained in step (3) is calcined at 650°C for 4 hours in a mixed gas with an air-oxygen volume ratio of 1:1.5 to obtain a porous catalyst.
[0049] The specific surface area of the porous catalyst obtained in Example 1 was measured using N2 adsorption / desorption isotherm analysis (Micromeritics ASAP 2460 analyzer). The specific surface area of the porous catalyst in Example 1 was 442 m². 2 / g.
[0050] The porous catalyst in Example 1 was observed using a scanning electron microscope, and the obtained SEM image is shown below. Figure 1 As shown, from Figure 1 As can be seen, this porous catalyst has a distinct porous structure, a high specific surface area, and good pore connectivity. These structural features contribute to its excellent activity and mass transfer performance in catalytic reactions.
[0051] Example 2 A method for preparing a porous catalyst comprises the following steps: (1) Iron slag and acid solution (a mixed solution of 5wt% dilute hydrochloric acid and 5wt% dilute acetic acid, with a mass ratio of 17:1) were heated and stirred at 60°C for 5 hours at a mass ratio of 1:5 for the first mixing, and then filtered to obtain metal ion filtrate. (2) The metal ion filtrate obtained in step (1) is mixed with an oxidant (2wt% hydrogen peroxide solution) at a mass ratio of 1:5 at 35°C and stirred for 2 hours to obtain a high-valence metal ion solution. (3) The high-valence metal ion solution, precipitant (0.1wt% ammonia water) and nano carbon powder obtained in step (2) are mixed in a mass ratio of 10:2:1 and then subjected to hydrothermal reaction at 105°C for 22h in a reactor. The hydrothermal reaction product is then filtered and rinsed 5 times with pure water, and then dried at 105°C for 10h to obtain the catalyst precursor. (4) The catalyst precursor obtained in step (3) is calcined at 900°C for 2 hours in a mixture of air and oxygen in a volume ratio of 1:3 to obtain a porous catalyst.
[0052] The specific surface area of the porous catalyst obtained in Example 2 was tested using N2 adsorption / desorption isotherm analysis (Micromeritics ASAP 2460 analyzer). The specific surface area of the porous catalyst in Example 2 was 357 m². 2 / g.
[0053] Example 3 A method for preparing a porous catalyst comprises the following steps: (1) Manganese slag and acid solution (a mixed solution of 5wt% dilute hydrochloric acid and 5wt% dilute acetic acid, with a mass ratio of 10:1) were heated and stirred at 75°C for 1.5h for the first mixing, and then filtered to obtain metal ion filtrate. (2) The metal ion filtrate obtained in step (1) is mixed with an oxidant (2.5wt% hydrogen peroxide solution) at a mass ratio of 1:8 and heated and stirred at 40°C for 5 hours to obtain a high-valence metal ion solution. (3) The high-valence metal ion solution, precipitant (0.35wt% ammonia water) and nano carbon powder obtained in step (2) are mixed in a mass ratio of 20:3:1 and then subjected to hydrothermal reaction at 120°C for 30h in a reactor. The hydrothermal reaction product is then filtered and rinsed 5 times with pure water, and then dried at 105°C for 10h to obtain the catalyst precursor. (4) The catalyst precursor obtained in step (3) is calcined at 850°C for 1 hour in a mixed gas with an air-oxygen volume ratio of 1:0.5 to obtain a porous catalyst.
[0054] The specific surface area of the porous catalyst obtained in Example 3 was tested using N2 adsorption / desorption isotherm analysis (Micromeritics ASAP 2460 analyzer). The specific surface area of the porous catalyst in Example 3 was 413 m². 2 / g.
[0055] Example 4 A method for preparing a porous catalyst comprises the following steps: (1) The zinc slag and acid solution (a mixed solution of 5wt% dilute hydrochloric acid and 5wt% dilute acetic acid, with a mass ratio of 15:1) were heated and stirred at 55°C for 3 hours in a mass ratio of 1:6 to obtain a metal ion filtrate. (2) The metal ion filtrate obtained in step (1) is mixed with an oxidant (1 wt% sodium hypochlorite solution) at a mass ratio of 1:4 at 45°C and stirred for 12 h to obtain a high-valence metal ion solution. (3) The high-valence metal ion solution, precipitant (0.2wt% sodium hydroxide solution) and nano carbon powder obtained in step (2) are mixed in a mass ratio of 15:4:1 and then subjected to hydrothermal reaction at 130°C for 15h in a reactor. The hydrothermal reaction product is then filtered and rinsed 5 times with pure water, and then dried at 105°C for 10h to obtain the catalyst precursor. (4) The catalyst precursor obtained in step (3) is calcined at 500°C for 2.5 h in a mixed gas with an air-oxygen volume ratio of 1:2.5 to obtain a porous catalyst.
[0056] The specific surface area of the porous catalyst obtained in Example 4 was tested using N2 adsorption / desorption isotherm analysis (Micromeritics ASAP 2460 analyzer). The specific surface area of the porous catalyst in Example 4 was 394 m². 2 / g.
[0057] Example 5 A method for preparing a porous catalyst comprises the following steps: (1) Aluminum slag and acid solution (a mixed solution of 5wt% dilute hydrochloric acid and 5wt% dilute acetic acid, with a mass ratio of 12:1) were heated and stirred at 85°C for 1 hour at a mass ratio of 1:10 to obtain metal ion filtrate. (2) The metal ion filtrate obtained in step (1) is mixed with an oxidant (3wt% hydrogen peroxide solution) at a mass ratio of 1:3 at 25°C and stirred for 8 hours to obtain a high-valence metal ion solution; (3) The high-valence metal ion solution, precipitant (0.45wt% sodium hydroxide solution) and nano carbon powder obtained in step (2) are mixed in a mass ratio of 13:3:1 and then subjected to hydrothermal reaction at 110°C for 12 hours in a reactor. The hydrothermal reaction product is then filtered and rinsed 5 times with pure water, and then dried at 105°C for 10 hours to obtain the catalyst precursor. (4) The catalyst precursor obtained in step (3) is calcined at 700°C for 5 hours in a mixture of air and oxygen in a volume ratio of 1:2 to obtain a porous catalyst.
[0058] The specific surface area of the porous catalyst obtained in Example 5 was tested using N2 adsorption / desorption isotherm analysis (Micromeritics ASAP 2460 analyzer). The specific surface area of the porous catalyst in Example 5 was 388 m². 2 / g.
[0059] Comparative Example 1 The only difference between Comparative Example 1 and Example 1 is that dilute acetic acid was not added, and the acid solution was 5 wt% dilute hydrochloric acid. Otherwise, they are the same as in Example 1.
[0060] The specific surface area of the porous catalyst obtained in Comparative Example 1 was measured using N2 adsorption / desorption isotherm analysis (Micromeritics ASAP 2460 analyzer). The specific surface area of the porous catalyst in Comparative Example 1 was 188 m². 2 / g.
[0061] Comparative Example 2 The only difference between Comparative Example 2 and Example 1 is that step (2) is omitted; otherwise, they are the same as in Example 1.
[0062] The specific surface area of the porous catalyst obtained in Comparative Example 2 was measured using N2 adsorption / desorption isotherm analysis (Micromeritics ASAP 2460 analyzer). The specific surface area of the porous catalyst in Comparative Example 2 was 247 m². 2 / g.
[0063] Comparative Example 3 The only difference between Comparative Example 3 and Example 1 is that nano-carbon powder was not added in step (3), otherwise it is the same as Example 1.
[0064] The specific surface area of the porous catalyst obtained in Comparative Example 3 was measured using N2 adsorption / desorption isotherm analysis (Micromeritics ASAP 2460 analyzer). The specific surface area of the porous catalyst in Comparative Example 3 was 283 m². 2 / g.
[0065] Comparative Example 4 The only difference between Comparative Example 4 and Example 1 is that the addition of oxygen is omitted in step (3), otherwise it is the same as Example 1.
[0066] The specific surface area of the porous catalyst obtained in Comparative Example 4 was measured using N2 adsorption / desorption isotherm analysis (Micromeritics ASAP 2460 analyzer). The specific surface area of the porous catalyst in Comparative Example 4 was 193 m². 2 / g.
[0067] Test case The catalyst activity was tested in a fixed-bed quartz reactor under the following conditions: industrial waste gas: SO2 concentration 200 ppm, NO... x (NO:NO2 = 4:1) Concentration 500 ppm, space velocity 10000 h⁻¹ -1 The reaction temperature was 160℃, and ammonia gas was introduced during the reaction at a concentration of 2000 ppm and a space velocity of 10000 h⁻¹. -1 .
[0068] Porous catalysts in Examples 1-5 and Comparative Examples 1-4 for the effects of SO2 and NO in industrial waste gas x Table 1 shows the removal efficiency and service life data of the porous catalyst for SO2 and NO. x The reaction time when the removal performance drops to 90%.
[0069] Table 1. Effects of porous catalysts from Examples 1-5 and Comparative Examples 1-4 on SO2 and NO in industrial waste gas. x Removal effect and lifespan data
[0070] Table 1 shows the SO2 and NO content of the catalysts prepared in Examples 1-5. x The removal performance is far superior to that of comparative examples 1-4, achieving 100% removal of SO2 and NO under the above reaction conditions. x It has a higher removal efficiency and a much longer service life than the comparative example, and can simultaneously desulfurize and denitrify at a lower reaction temperature.
[0071] The porous catalyst prepared by the method provided in this invention has an operating temperature of 160~450℃, and can handle SO2 and NO. x The removal efficiency reaches 100%, the service life can reach more than 130 hours, and it has higher SO2 and NO removal efficiency. x It boasts high removal efficiency, a wide operating temperature range, and a long service life, enabling simultaneous desulfurization and denitrification at relatively low reaction temperatures.
[0072] The above description is only a preferred embodiment of the present invention. It should be noted that for those skilled in the art, several improvements and modifications can be made without departing from the principle of the present invention, and these improvements and modifications should also be considered within the scope of protection of the present invention.
Claims
1. A method for preparing a porous catalyst, comprising the following steps: (1) filtering after first mixing slag with an acid solution to obtain a metal ion filtrate; the acid solution is a mixed solution of dilute hydrochloric acid and dilute acetic acid; (2) second mixing the metal ion filtrate obtained in step (1) with an oxidizing agent to obtain a high-valence metal ion solution; (3) third mixing the high-valence metal ion solution obtained in step (2), a precipitant and carbon powder, and then performing a hydrothermal reaction to obtain a catalyst precursor; (4) performing oxygen-rich roasting on the catalyst precursor obtained in step (3) to obtain a porous catalyst.
2. The production method according to claim 1, characterized by, The concentration of the dilute hydrochloric acid in step (1) is 5-10 wt%, and the concentration of the dilute acetic acid is 5-8 wt%. The mass ratio of the dilute hydrochloric acid to the dilute acetic acid is (10-20) :
1.
3. The preparation method according to claim 1, characterized in that, The mass ratio of the metal ion filtrate to the oxidizing agent in step (2) is 1 : (3-8).
4. The production method according to claim 1 or 3, characterized by, The oxidizing agent in step (2) is hydrogen peroxide solution or sodium hypochlorite solution. The concentration of the hydrogen peroxide solution or the sodium hypochlorite solution is independently 0.5-3 wt%.
5. The method of claim 1, wherein, The mass ratio of the high-valence metal ion solution, the precipitant and the carbon powder in step (3) is (10-20) : (2-5) :
1.
6. The production method according to claim 1 or 5, characterized by, The precipitant in step (3) is sodium hydroxide solution or ammonia water. The concentration of the sodium hydroxide solution or the ammonia water is independently 0.1-0.5 wt%.
7. The preparation method according to claim 1, characterized in that, The temperature of the hydrothermal reaction in step (3) is 75-130℃, and the time of the hydrothermal reaction is 12-48 h.
8. The method of claim 1, wherein, The temperature of the oxygen-rich roasting in step (4) is 500-900℃, and the time of the oxygen-rich roasting is 1-5 h. 9.The porous catalyst prepared by the method of any one of claims 1-8. 10.The application of the porous catalyst of claim 9 in industrial waste gas desulfurization and denitrification.