Preparation method of catalyst for catalytic reduction of SO2 by CO in oxygen-containing atmosphere

Abstract

The invention discloses a preparation method of a catalyst for catalytic reduction of SO2 by CO in an oxygen-containing atmosphere, and belongs to the technical field of atmospheric pollution purification. According to the catalyst, base metals such as Fe and Cu are adopted to modify supported metal sulfide, active components of the supported metal sulfide comprise FeS, CoS2, CuS and the like, and common metal oxides such as cerium oxide, titanium oxide, aluminum oxide and the like are selected as carriers. The catalyst not only has strong SO2 catalytic reduction performance and high stability in an oxygen-containing atmosphere, but also is simple in preparation process, wide in raw material source and low in cost, has remarkable economical efficiency and environmental protection benefits, has a wide application prospect in the field of air pollution purification, and has important significance in reducing SO2 emission and improving air quality. The embodiment shows that when the oxygen volume content of the Fe elementary substance modified supported metal sulfide composite catalyst is 5%, the SO2 conversion rate is 97.9%, and the sulfur yield is 90.6%.

Description

Technical Field

[0001] This invention belongs to the field of atmospheric pollution purification technology, and relates to a method for preparing a catalyst for the catalytic reduction of SO2 by CO in an oxygen-containing atmosphere. Background Technology

[0002] Currently, flue gas desulfurization can be mainly divided into absorption, adsorption, and catalytic reduction methods. Among them, the limestone-gypsum method is the most mature and widely used desulfurization process, but it suffers from problems such as high initial investment costs, high operating costs, large land area requirements, and the generation of large amounts of by-products and difficult wastewater treatment. Catalytic reduction not only has the advantage of no waste treatment issues, but also enables sulfur recovery. Reducing gases such as CO, CH4, H2, and C2H4 can reduce SO2 to sulfur. According to data from the National Bureau of Statistics, my country's sulfur imports in 2023 reached 8.8334 million tons, therefore, catalytic reduction also has significant commercial value. The flue gas from the steel industry contains not only large amounts of SO2 (approximately 1000-3000 mg / m³) but also significant amounts of CO (approximately 5000-15000 mg / m³) that are emitted into the atmosphere without treatment. With increasing emphasis on CO emissions, Tangshan, Hebei Province, issued a "Notice on Launching a Campaign to Reduce SO2, NO2, and CO Pollutants," explicitly requiring atmospheric CO concentrations to be below 25 mg / m³. Meanwhile, Handan City requires sintering machines to emit less than 6000 mg / m³ of CO per hour. Therefore, utilizing CO in flue gas for catalytic reduction of SO2 can not only reduce CO and SO2 emissions, meeting the carbon reduction targets of enterprises, but also convert SO2 in the flue gas into sulfur for recovery, reducing my country's dependence on imported sulfur.

[0003] CN 117065755 A discloses a catalyst for the catalytic reduction of SO2 to sulfur using CO and its preparation method. The method first prepares Co3O4 nanorods using a hydrothermal method, with dimethyl sulfoxide (DMSO) as the solvent. Ce(NO3)3·6H2O and Gd(NO3)3·6H2O were fully loaded onto Co3O4 nanorods and pre-sulfurized with 1% SO2 and 2% CO to obtain the final sulfidized catalyst. This catalyst exhibits an SO2 conversion rate of approximately 96% at 400℃. However, the influence of oxygen in the flue gas on the catalyst's SO2 reduction was not investigated, and the high cost of its raw material, gadolinium (Gd), makes industrialization difficult.

[0004] CN109999804B catalyst, based on alumina support, is doped with lanthanum oxide and cerium oxide, which stabilizes the alumina structure, increases the pore structure of the support, and produces abundant mesopores. This promotes the oxygen transport capacity of the support components and improves the sulfur capacity, enabling effective catalytic reduction of SO2 under oxygen-containing and water vapor conditions. However, its catalyst preparation process is too complex, and it requires increasing the content of noble metal oxides iridium oxide and ruthenium oxide to reduce the maximum conversion temperature of CO to SO2.

[0005] Therefore, there is an urgent need to develop a new type of catalyst that not only has a simple and quick preparation process, but also has excellent antioxidant properties and high catalytic activity to meet the requirements of practical applications. Summary of the Invention

[0006] To address the aforementioned problems, this invention provides a method for preparing a catalyst for the catalytic reduction of SO2 from CO in an oxygen-containing atmosphere. This catalyst maintains high activity and high stability for the catalytic reduction of SO2 from CO in an oxygen-containing atmosphere, thereby simultaneously purifying CO and SO2 in flue gas and recovering the reduced sulfur.

[0007] The objective of this invention can be achieved through the following technical solutions: A method for preparing a catalyst for the catalytic reduction of SO2 by CO in an oxygen-containing atmosphere includes the following steps: Metal ions are adsorbed onto a support by impregnation, followed by drying and heat treatment to convert the metal ions into metal oxides. Then, the metal oxides are sulfided using a sulfiding agent to obtain a supported sulfide catalyst. A composite catalyst was obtained by modifying a single metal supported sulfide catalyst using a mechanical mixing method. Flue gas containing CO, SO2, O2 and N2 is then introduced, and a composite catalyst enhances the reduction of SO2 from CO to sulfur vapor, which is then condensed and recovered.

[0008] Preferably, the metal loading is 2wt%-10wt%.

[0009] Preferably, the initial sludge concentration is set within the range of 15,000-25,000 mg / L, the anaerobic digestion temperature is set within the range of 35-39℃, the working water level depth is set within the range of 0.6-0.8 m, and the treatment load is set within the range of 3-5 kg ​​COD / m³. Preferred options include: (1) Take 2-8g of metal oxide carrier and grind it to make its particle size uniform. Place the ground carrier in an oven and dry it at an appropriate temperature to constant weight to remove the moisture and volatile impurities on its surface and obtain the carrier. (2) Accurately weigh a certain amount of base metal nitrate, dissolve it in deionized water, and prepare a nitrate solution of a certain concentration; slowly add the carrier obtained in step (1) into the prepared nitrate solution, and use a magnetic stirrer to stir the solution magnetically so that the nitrate solution fully wets the surface of the carrier; after soaking for 0.5-2h, dry it in air at 110-130℃ for 16-36h, grind the dried solid and put it into a muffle furnace for calcination, with a heating rate of 1-5℃ / min, a calcination temperature of 300-700℃, and a calcination time of 1-8h; (3) Grind and sieve the solid after calcination in step (2), and place the powder of 80-100 mesh into a mixed gas containing 2%-6% CO and 1%-2% SO2, with the remainder being N2, at a space velocity of 6000-10000 h⁻¹. -1 The catalyst was pre-sulfurized at 400-500℃ for 2-4 hours to obtain a supported sulfide catalyst. (4) Take the elemental metal and grind and sieve it to obtain 80-100 mesh powder, named powder 1. Grind and sieve the solid catalyst after sulfidation in step (3) to 80-100 mesh powder, named powder 2. Put powder 1 and powder 2 into a mixer and mix for 1-4 hours to obtain powder 3. Grind powder 3 and use a tablet press to press it into tablets. Finally, after crushing and sieving, it is calcined at a constant temperature to obtain the composite catalyst modified by the elemental metal.

[0010] Preferably, the metal oxide support in step (1) is one or more of CeO2, TiO2, Al2O3, and SiO2.

[0011] Preferably, the appropriate temperature in step (1) is 120-140℃.

[0012] Preferably, the base metal nitrate in step (2) is one or more of ferric nitrate, cobalt nitrate, copper nitrate, nickel nitrate and manganese nitrate.

[0013] Preferably, the magnetic stirring time in step (2) is 30-90 min.

[0014] Preferably, the pre-sulfurization process in step (3) is carried out in a catalytic reduction device.

[0015] Preferably, the elemental metal in step (4) includes Fe, Cu, Co, Mn, and Ni, the pressure of the tableting process is 20-40 MPa, the constant temperature calcination temperature is 400-600℃, and the constant temperature calcination time is 1-3 h.

[0016] Compared with the prior art, the present invention has the following beneficial effects: When treating organic wastewater, this invention can achieve the following beneficial effects: 1. The composite catalyst prepared by this invention exhibits excellent catalytic activity and stability for the reduction of SO2 from CO in an oxygen-containing atmosphere.

[0017] 2. The catalyst raw materials prepared by the method of the present invention are readily available, the preparation process is simple, and it is suitable for industrial applications. Detailed Implementation

[0018] To enable those skilled in the art to better understand the technical solutions of the present invention, the preferred embodiments of the present invention are described below in conjunction with specific examples. However, it should be understood that the embodiments listed in the present invention should not be construed as limiting the present patent.

[0019] Comparative Example 1 Accurately weigh 2-8g of CeO2, grind and dry it for later use. Accurately weigh 0.5-2g of ferric nitrate and dissolve it in deionized water to prepare a 0.5-1mol / L ferric nitrate solution. Slowly add the CeO2 carrier to the prepared ferric nitrate solution, stir the solution with a magnetic stirrer for 30-90 min, then soak it for 0.5-2 h, and dry it in air at 110-130℃ for 16-36 h. After drying, grind the solid and calcine it in a muffle furnace at a heating rate of 1-5℃ / min, a calcination temperature of 300-700℃, and a calcination time of 1-8 h. Grind and sieve the calcined solid, and select 80-100 mesh powder. Place it in a catalytic reduction reaction device in a mixed gas containing 2%-6% CO, 1%-2% SO2, and the remainder N2, with a space velocity of 6000-10000 h⁻¹. -1 Pre-sulfurize it at 400-500℃ for 2-4 hours, and then grind and sieve it to obtain an 80-100 mesh supported sulfide catalyst.

[0020] The catalyst obtained by the above method was used for the catalytic reduction of SO2 from CO at a reaction temperature of 300-500℃ and a volume hourly space velocity of 10000 h⁻¹. -1 It contains 2%-6% CO and 1%-2% SO2, and 2%-8% O2 and N2 in equilibrium. A shell-and-tube condenser is installed at the end of the quartz tube to condense the sulfur vapor into a solid and collect the sulfur.

[0021] Comparative Example 2 Accurately weigh 2-8g of TiO2, grind and dry it for later use. Accurately weigh 0.5-2g of cobalt nitrate and dissolve it in deionized water to prepare a 0.5-1mol / L cobalt nitrate solution. Slowly add the TiO2 support to the prepared cobalt nitrate solution, stir the solution with a magnetic stirrer for 30-90 min, then impregnate for 0.5-2 h, and dry in air at 110-130℃ for 16-36 h. After drying, grind the solid and calcine it in a muffle furnace at a heating rate of 1-5℃ / min, a calcination temperature of 300-700℃, and a calcination time of 1-8 h. Grind and sieve the calcined solid, and select 80-100 mesh powder. Place it in a catalytic reduction reaction device in a mixed gas containing 2%-6% CO, 1%-2% SO2, and the remainder N2, with a space velocity of 6000-10000 h⁻¹. -1 Pre-sulfurize it at 400-500℃ for 2-4 hours, and then grind and sieve it to obtain an 80-100 mesh supported sulfide catalyst.

[0022] The catalyst obtained by the above method was used for the catalytic reduction of SO2 from CO at a reaction temperature of 300-500℃ and a volume hourly space velocity of 10000 h⁻¹. -1 It contains 2%-6% CO and 1%-2% SO2, and 2%-8% O2 and N2 in equilibrium. A shell-and-tube condenser is installed at the end of the quartz tube to condense the sulfur vapor into a solid and collect the sulfur.

[0023] Example 1 After grinding and sieving elemental iron to obtain 80-100 mesh metal iron powder, it was mixed with the supported sulfide catalyst prepared in Comparative Example 1 in a mixer for 1-4 hours. Then, it was tableted using a tablet press at 20-40 MPa. Finally, after crushing and sieving, it was calcined at 400-600℃ to obtain the elemental metal modified composite catalyst.

[0024] The composite catalyst obtained by the above method was applied to the catalytic reduction of SO2 from CO at a reaction temperature of 300-500℃ and a volume hourly space velocity of 10000 h⁻¹. -1 It contains 2%-6% CO and 1%-2% SO2, and 2%-8% O2 and N2 in equilibrium. A shell-and-tube condenser is installed at the end of the quartz tube to condense the sulfur vapor into a solid and collect the sulfur.

[0025] Example 2 After grinding and sieving elemental iron to obtain 80-100 mesh metal iron powder, it was mixed with the supported sulfide catalyst prepared in Comparative Example 2 in a mixer for 1-4 hours. Then, it was tableted using a tablet press at 20-40 MPa. Finally, after crushing and sieving, it was calcined at 400-600℃ to obtain the elemental metal modified composite catalyst.

[0026] The composite catalyst obtained by the above method was applied to the catalytic reduction of SO2 from CO at a reaction temperature of 300-500℃ and a volume hourly space velocity of 10000 h⁻¹. -1 It contains 2%-6% CO and 1%-2% SO2, and 2%-8% O2 and N2 in equilibrium. A shell-and-tube condenser is installed at the end of the quartz tube to condense the sulfur vapor into a solid and collect the sulfur.

[0027] Example 3 After grinding and sieving elemental copper to obtain 80-100 mesh copper powder, it was mixed with the supported sulfide catalyst prepared in Comparative Example 1 in a mixer for 1-4 hours. Then, it was tableted at 20-40 MPa using a tablet press. Finally, after crushing and sieving, it was calcined at 400-600℃ to obtain the elemental metal modified composite catalyst.

[0028] The composite catalyst obtained by the above method was applied to the catalytic reduction of SO2 from CO at a reaction temperature of 300-500℃ and a volume hourly space velocity of 10000 h⁻¹. -1 It contains 2%-6% CO and 1%-2% SO2, and 2%-8% O2 and N2 in equilibrium. A shell-and-tube condenser is installed at the end of the quartz tube to condense the sulfur vapor into a solid and collect the sulfur.

[0029] Example 4 After grinding and sieving elemental nickel to obtain 80-100 mesh nickel powder, it was mixed with the supported sulfide catalyst prepared in Comparative Example 1 in a mixer for 1-4 hours. Then, it was tableted at 20-40 MPa using a tablet press. Finally, after crushing and sieving, it was calcined at 400-600℃ to obtain the elemental metal modified composite catalyst.

[0030] The composite catalyst obtained by the above method was applied to the catalytic reduction of SO2 from CO at a reaction temperature of 300-500℃ and a volume hourly space velocity of 10000 h⁻¹. -1 It contains 2%-6% CO and 1%-2% SO2, and 2%-8% O2 and N2 in equilibrium. A shell-and-tube condenser is installed at the end of the quartz tube to condense the sulfur vapor into a solid and collect the sulfur.

[0031] Example 5 Accurately weigh 2-8g of Al₂O₃, grind and dry it for later use. Accurately weigh 0.5-2g of ferric nitrate and dissolve it in deionized water to prepare a 0.5-1mol / L ferric nitrate solution. Slowly add the Al₂O₃ carrier to the prepared ferric nitrate solution, stir the solution with a magnetic stirrer for 30-90 min, then impregnate for 0.5-2 h, and dry in air at 110-130℃ for 16-36 h. After drying, grind the solid and calcine it in a muffle furnace at a heating rate of 1-5℃ / min, a calcination temperature of 300-700℃, and a calcination time of 1-8 h. Grind and sieve the calcined solid, and select 80-100 mesh powder. Place it in a catalytic reduction reaction apparatus in a mixed gas containing 2%-6% CO, 1%-2% SO₂, and the remainder N₂, with a space velocity of 6000-10000 h⁻¹. -1 The catalyst is pre-sulfurized at 400-500℃ for 2-4 hours, and then ground and sieved to obtain a 40-60 mesh supported sulfide catalyst. Elemental iron is ground and sieved to obtain 80-100 mesh metallic iron powder, which is then mixed with the supported sulfide catalyst in a mixer for 1-4 hours. The mixture is then pressed into tablets at 20-40 MPa using a tablet press. Finally, after crushing and sieving, the tablets are calcined at 400-600℃ to obtain the elemental metal-modified composite catalyst.

[0032] The composite catalyst obtained by the above method was applied to the catalytic reduction of SO2 from CO at a reaction temperature of 300-500℃ and a volume hourly space velocity of 10000 h⁻¹. -1 It contains 2%-6% CO and 1%-2% SO2, and 2%-8% O2 and N2 in equilibrium. A shell-and-tube condenser is installed at the end of the quartz tube to condense the sulfur vapor into a solid and collect the sulfur.

[0033] Example 6 Accurately weigh 2-8g of CeO2, grind and dry it for later use. Accurately weigh 0.5-2g of copper nitrate and dissolve it in deionized water to prepare a 0.5-1mol / L copper nitrate solution. Slowly add the CeO2 carrier to the prepared copper nitrate solution, stir the solution with a magnetic stirrer for 30-90 min, then soak it for 0.5-2 h, and dry it in air at 110-130℃ for 16-36 h. After drying, grind the solid and calcine it in a muffle furnace at a heating rate of 1-5℃ / min, a calcination temperature of 300-700℃, and a calcination time of 1-8 h. Grind and sieve the calcined solid, and select 80-100 mesh powder. Place it in a catalytic reduction reaction device in a mixed gas containing 2%-6% CO, 1%-2% SO2, and the remainder N2, with a space velocity of 6000-10000 h⁻¹. -1The catalyst is pre-sulfurized at 400-500℃ for 2-4 hours, and then ground and sieved to obtain a 40-60 mesh supported sulfide catalyst. Elemental iron is ground and sieved to obtain 80-100 mesh metallic iron powder, which is then mixed with the supported sulfide catalyst in a mixer for 1-4 hours. The mixture is then pressed into tablets at 20-40 MPa using a tablet press. Finally, after crushing and sieving, the tablets are calcined at 400-600℃ to obtain the elemental metal-modified composite catalyst.

[0034] The composite catalyst obtained by the above method was applied to the catalytic reduction of SO2 from CO at a reaction temperature of 300-500℃ and a volume hourly space velocity of 10000 h⁻¹. -1 It contains 2%-6% CO and 1%-2% SO2, and 2%-8% O2 and N2 in equilibrium. A shell-and-tube condenser is installed at the end of the quartz tube to condense the sulfur vapor into a solid and collect the sulfur.

[0035] The catalytic activity of the catalysts prepared in the above six examples and two comparative examples was tested under the following conditions: catalyst loading was 1.0 g (80-100 mesh), gas mixture of 1500 ppm CO, 500 ppm SO2, 5% O2, and the remainder being N2, and the reaction space velocity was 6000 ml·h. -1 The test results are shown in the table below:

[0036] As can be seen from the table above, the introduction of elemental metals can enhance the catalytic reduction performance and stability of the catalyst in the CO-SO2 reduction in an oxygen-containing atmosphere, but there are some differences. The catalytic reduction performance and stability of the catalyst are the best when elemental metal iron is introduced.

[0037] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention and are not intended to limit it. Although the present invention has been described in detail with reference to preferred embodiments, those skilled in the art should understand that modifications or equivalent substitutions can be made to the technical solutions of the present invention without departing from the spirit and scope of the technical solutions of the present invention, and all such modifications or substitutions should be covered within the scope of the claims of the present invention.

Claims

1. A method for preparing a catalyst for the catalytic reduction of SO2 by CO in an oxygen-containing atmosphere, characterized in that, Includes the following steps: Metal ions are adsorbed onto a support by impregnation, followed by drying and heat treatment to convert the metal ions into metal oxides. Then, the metal oxides are sulfided using a sulfiding agent to obtain a supported sulfide catalyst. A composite catalyst was obtained by modifying a single metal supported sulfide catalyst using a mechanical mixing method. Flue gas containing CO, SO2, O2 and N2 is then introduced, and a composite catalyst enhances the reduction of SO2 from CO to sulfur vapor, which is then condensed and recovered.

2. The method for preparing the catalyst for the catalytic reduction of SO2 by CO in an oxygen-containing atmosphere according to claim 1, characterized in that, The metal loading is 2wt%-10wt%.

3. The method for preparing the catalyst for the catalytic reduction of SO2 by CO in an oxygen-containing atmosphere according to claim 1, characterized in that, The initial sludge concentration is set within the range of 15,000-25,000 mg / L, the anaerobic digestion temperature is set at 35-39℃, the working water level depth is set at 0.6-0.8m, and the treatment load is set at 3-5 kg ​​COD / m³.

4. The method for preparing the catalyst for the catalytic reduction of SO2 by CO in an oxygen-containing atmosphere according to claim 1, characterized in that, Specifically, it includes: (1) Take 2-8g of metal oxide carrier and grind it to make its particle size uniform. Place the ground carrier in an oven and dry it at an appropriate temperature to constant weight to remove the moisture and volatile impurities on its surface and obtain the carrier. (2) Accurately weigh a certain amount of base metal nitrate, dissolve it in deionized water, and prepare a nitrate solution of a certain concentration; slowly add the carrier obtained in step (1) into the prepared nitrate solution, and use a magnetic stirrer to stir the solution magnetically so that the nitrate solution fully wets the surface of the carrier; after soaking for 0.5-2h, dry it in air at 110-130℃ for 16-36h, grind the dried solid and put it into a muffle furnace for calcination, with a heating rate of 1-5℃ / min, a calcination temperature of 300-700℃, and a calcination time of 1-8h; (3) Grind and sieve the solid after calcination in step (2), and place the powder of 80-100 mesh into a mixed gas containing 2%-6% CO and 1%-2% SO2, with the remainder being N2, at a space velocity of 6000-10000 h⁻¹. -1 The catalyst was pre-sulfurized at 400-500℃ for 2-4 hours to obtain a supported sulfide catalyst. (4) Take the elemental metal and grind and sieve it to obtain 80-100 mesh powder, named powder 1. Grind and sieve the solid catalyst after sulfidation in step (3) to 80-100 mesh powder, named powder 2. Put powder 1 and powder 2 into a mixer and mix for 1-4 hours to obtain powder 3. Grind powder 3 and use a tablet press to press it into tablets. Finally, after crushing and sieving, it is calcined at a constant temperature to obtain the composite catalyst modified by the elemental metal.

5. The method for preparing the catalyst for the catalytic reduction of SO2 by CO in an oxygen-containing atmosphere according to claim 4, characterized in that, The metal oxide support in step (1) is one or more of CeO2, TiO2, Al2O3, and SiO2.

6. The method for preparing the catalyst for the catalytic reduction of SO2 by CO in an oxygen-containing atmosphere according to claim 4, characterized in that, The appropriate temperature in step (1) is 120-140℃.

7. The method for preparing the catalyst for the catalytic reduction of SO2 by CO in an oxygen-containing atmosphere according to claim 4, characterized in that, The base metal nitrate mentioned in step (2) is one or more of ferric nitrate, cobalt nitrate, copper nitrate, nickel nitrate and manganese nitrate.

8. The method for preparing the catalyst for the catalytic reduction of SO2 by CO in an oxygen-containing atmosphere according to claim 4, characterized in that, The magnetic stirring time in step (2) is 30-90 min.

9. The method for preparing the catalyst for the catalytic reduction of SO2 by CO in an oxygen-containing atmosphere according to claim 4, characterized in that, The pre-sulfurization in step (3) is carried out in a catalytic reduction device.

10. The method for preparing the catalyst for the catalytic reduction of SO2 by CO in an oxygen-containing atmosphere according to claim 4, characterized in that, The elemental metals in step (4) include Fe, Cu, Co, Mn, and Ni. The pressure of the tableting process is 20-40 MPa. The constant temperature calcination temperature is 400-600℃ and the constant temperature calcination time is 1-3 hours.

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