Calcium-based desulfurizing agent and preparation method thereof
By combining modified calcium hydroxide and activated carbon, a porous calcium-based desulfurizer was prepared, which solved the problem of pore blockage during the use of calcium-based desulfurizer and improved the removal efficiency and utilization rate of SO2.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2026-03-03
- Publication Date
- 2026-03-31
AI Technical Summary
During use, existing calcium-based desulfurizers experience surface densification and pore blockage, leading to decreased desulfurization efficiency and reduced utilization.
Using modified calcium hydroxide, modified activated carbon, alkali metal compounds, and composite binders as raw materials, a porous calcium-based desulfurizer was prepared through multi-stage hydrothermal reaction and modification with iron oxides and magnesium oxides loaded on oxidized activated carbon. This process enhanced the pore structure and reactivity, and prevented the solid products from covering the desulfurizer.
It improves the removal efficiency and utilization rate of SO2 by calcium-based desulfurizer, extends the active cycle, prevents pore blockage, and enhances adsorption capacity and reactivity.
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Abstract
Description
Technical Field
[0001] This invention relates to a calcium-based desulfurizing agent and its preparation method, belonging to the field of flue gas desulfurization technology. Background Technology
[0002] Calcium-based desulfurizers, typically represented by slaked lime (Ca(OH)2), possess characteristics such as readily available and inexpensive raw materials, good desulfurization activity, and stable, insoluble, and recyclable sulfur-fixing products, making them the most widely used desulfurizers in the current field of industrial flue gas desulfurization. However, with increasingly stringent environmental standards and the need for sustainable development in the industry, existing calcium-based desulfurizers have certain shortcomings: during the desulfurization process, a product layer (solid products such as CaSO3 and CaSO4) covers the surface of the desulfurizer, leading to surface densification and pore blockage, which in turn hinders the diffusion of gaseous substances (SO2, O2, and other gas molecules) into the interior of the desulfurizer, resulting in a decrease in desulfurization efficiency and utilization rate. Therefore, there is an urgent need for a calcium-based desulfurizer and its preparation method that can improve desulfurization efficiency and utilization rate. Summary of the Invention
[0003] In response to at least one problem existing in the prior art, the present invention provides a calcium-based desulfurizing agent and its preparation method. The prepared calcium-based desulfurizing agent has high activity, which can improve its removal efficiency of SO2 in flue gas and improve its utilization rate.
[0004] To achieve the above objectives, the present invention adopts the following technical solution: a calcium-based desulfurizing agent, comprising, by mass percentage, the following raw materials: 53-61% modified calcium hydroxide, 22-27% modified activated carbon, 4-8% alkali metal compound, 3-5% metal oxide, and 7-10% composite binder; The modified calcium hydroxide is obtained by modifying calcium hydroxide through multi-stage hydrothermal reaction and treatment with silicon dioxide and sodium silicate; The modified activated carbon is an oxidizing activated carbon loaded with iron oxide and magnesium oxide.
[0005] Preferably, in modified calcium hydroxide, the amount of silicon dioxide is 5.8 to 7.2% of the mass of calcium hydroxide.
[0006] Preferably, the preparation process of the modified calcium hydroxide is as follows: 1) Mix calcium hydroxide with deionized water and place it in a hydrothermal reactor for a multi-stage hydrothermal reaction. First, heat to 150~160℃ and react in a sealed container for 100~120 min. Then, continue heating to 320~350℃ and react in a sealed container for 70~90 min. Then, continue heating to 580~600℃ and react in a sealed container for 30~50 min. Cool to room temperature, centrifuge and filter, and dry under vacuum at 90~95℃ for 1~2 h to obtain hydrated activated calcium hydroxide. 2) Mix silica with silicon coupling agent and grind for 20-30 minutes, then add hydrated activated calcium hydroxide and sodium silicate and continue grinding until the particle size is less than 0.2 μm to obtain modified calcium hydroxide.
[0007] Preferably, the calcium hydroxide in step 1) has a particle size of 0.1~0.15 mm.
[0008] Preferably, the mass ratio of calcium hydroxide to deionized water in step 1) is 1:6~8.
[0009] Preferably, the amount of silicon coupling agent used in step 2) is 0.5 to 1% of the mass of silicon dioxide.
[0010] Preferably, the amount of silicon dioxide used in step 3) is 5.8-7.2% of the mass of calcium hydroxide. Preferably, the amount of sodium silicate used in step 3) is 5-8% of the mass of silicon dioxide.
[0011] Preferably, the modified activated carbon contains iron in a molar ratio of 1.4 to 1.8:1 and has an iron oxide loading of 7 to 8%.
[0012] Preferably, the modified activated carbon preparation process is as follows: a. Dissolve ferric nitrate and magnesium nitrate in ethanol to form a metal ion solution with a total metal ion concentration of 0.12~0.14 mol / L. Then add citric acid, with a molar ratio of citric acid to total metal ions of 1.2~1.5:1. Stir until the solution is transparent, and then adjust the pH to 5~6 to obtain a transparent sol. b. Add oxidized activated carbon to the above transparent sol, stir evenly, sonicate at 450~500W for 30~35min, stir at 800~1000rpm for 3~5h, and vacuum dry at 85~90℃ for 2~3h to obtain a solid matrix. c. Heat-treat the solid matrix by raising the temperature to 420-450℃ at a rate of 2-5℃ / min and holding it at that temperature for 2-3 hours to obtain modified activated carbon.
[0013] Preferably, the molar ratio of iron ions to magnesium ions in step a is 1.4 to 1.8:1.
[0014] Preferably, the oxidized activated carbon in step b is obtained by treating activated carbon with hydrogen peroxide and ozone.
[0015] Preferably, the iron oxide loading in the modified activated carbon obtained in step c is 7-8%.
[0016] Preferably, the preparation process of the oxidized activated carbon is as follows: after washing, boiling and drying the activated carbon with water, it is soaked in a 15-20 (w / w)% hydrogen peroxide solution at a soaking temperature of 40-50°C for a total soaking time of 6-8 hours. During the soaking process, ozone is introduced for synergistic treatment for 2-3 hours. After the ozone synergistic treatment ends, it is soaked for another 0.5 hours, then filtered, washed and dried to obtain the oxidized activated carbon.
[0017] Preferably, the ratio of activated carbon to 15-20% (w / w)% hydrogen peroxide solution is 100g: 300-500ml; and the ozone injection rate is 6-8mg / L.
[0018] Preferably, the activated carbon has a particle size of 0.2~0.3 mm and a specific surface area of 950~1050 m². 2 / g.
[0019] Preferably, the alkali metal compound is either sodium carbonate or potassium carbonate.
[0020] Preferably, the metal oxide is a mixture composed of aluminum oxide, cerium oxide and copper oxide.
[0021] Preferably, the mass ratio of aluminum oxide, cerium oxide and copper oxide in the metal oxide is 3.5~4.5:1:2~3.
[0022] Preferably, the composite adhesive is a mixture composed of silica sol and sodium tripolyphosphate.
[0023] Preferably, the mass ratio of silica sol to sodium tripolyphosphate in the composite adhesive is 3~4:1.
[0024] Preferably, the content of nano-silica in the silica sol is 20-25%. This invention also provides a method for preparing a calcium-based desulfurizing agent, comprising the following steps: Step 1: Mix modified calcium hydroxide, modified activated carbon, alkali metal compound, and metal oxide evenly to form solid mixture A; Step 2: Add water to the solid mixture A and stir to wet it. The amount of water is 10-15% of the solid mixture A. Then add the composite adhesive and stir evenly. Granulate to obtain a semi-finished product. Step 3: Place the semi-finished product in a steam environment at a temperature of 220~250℃ and a pressure of 0.2~0.3MPa for 1~2 hours, and then dry it at a temperature of 110~120℃ to obtain calcium-based desulfurizer.
[0025] The beneficial effects of this invention are as follows: 1. This invention uses modified calcium hydroxide, modified activated carbon, alkali metal compounds, metal oxides, and composite binders as raw materials to prepare a calcium-based desulfurizer with high compressive strength and a porous structure. This desulfurizer possesses high adsorption capacity and reactivity, while also taking into account the characteristics of highly efficient activated carbon. This prevents the calcium-based desulfurizer from having its pores blocked by the produced calcium sulfate, thus improving the subsequent desulfurization effect, increasing the removal efficiency of SO2 from flue gas, and also enhancing its own utilization rate. 2. The modified calcium hydroxide of this invention is obtained by modifying calcium hydroxide through multi-stage hydrothermal reaction and treatment with silica and sodium silicate. This enhances the pore structure of calcium hydroxide and improves its surface activity, delaying the accumulation of solid products, providing channels for SO2 diffusion, extending the activity cycle of the calcium-based desulfurizer, and thus enhancing the removal effect of the calcium-based desulfurizer on SO2. 3. This invention uses modified activated carbon with iron oxide and magnesium oxide loaded on oxidized activated carbon for synergistic effect, enhancing the removal of SO2. While adsorbing SO2, this invention promotes its oxidation to SO3, reducing the formation of intermediate product CaSO3. Simultaneously, the porous structure of activated carbon prolongs the reaction time between SO2 and the calcium-based desulfurizer, effectively preventing solid products from covering the surface of the calcium-based desulfurizer and improving its utilization rate. 4. This invention also employs a synergistic metal oxide composite of alumina, cerium oxide, and copper oxide, which not only enhances SO2 adsorption but also promotes SO2 oxidation to SO3, accelerating the formation of CaSO4, reducing pore blockage caused by volume expansion, and simultaneously dispersing solid products to prevent rapid scaling at localized concentrations, thus affecting SO2 diffusion and the activity of the calcium-based desulfurizer. 5. This invention also uses a composite binder composed of silica sol and sodium tripolyphosphate, which strengthens the structure and improves the pore distribution of the calcium-based desulfurizer, while maintaining the permeability of the internal pores, facilitating SO2 diffusion and enhancing the activity and utilization rate of the calcium-based desulfurizer. Detailed Implementation
[0026] The following is a clear and complete description of the technical solutions in the implementation of this invention. The described embodiments are only a part of the embodiments of this invention, and not all of them. Based on the embodiments of this invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of this invention. Where specific conditions are not specified in the embodiments, conventional conditions or conditions recommended by the manufacturer shall apply. Reagents, instruments, or components used that do not specify the manufacturer are all conventional products that can be purchased commercially.
[0027] Example 1: Preparation of a modified calcium hydroxide 1.1 The preparation process of modified calcium hydroxide is as follows: 1) Calcium hydroxide with a particle size of 0.1~0.15mm was mixed with deionized water at a mass ratio of 1:6 and placed in a hydrothermal reactor for a multi-stage hydrothermal reaction. First, the mixture was heated to 150℃ and sealed for 120min, then heated to 335℃ and sealed for 70min, then heated to 600℃ and sealed for 30min. After cooling to room temperature, the mixture was centrifuged and filtered, and then vacuum dried at 90~95℃ for 1h to obtain hydrated activated calcium hydroxide. 2) Mix silica with a silicon coupling agent and grind for 25 minutes. The amount of silicon coupling agent is 0.65% of the mass of silica. Then add hydrated activated calcium hydroxide and sodium silicate and continue grinding until the particle size is less than 0.2 μm. The amount of silica is 5.8% of the mass of calcium hydroxide and the amount of sodium silicate is 8% of the mass of silica. Modified calcium hydroxide is obtained and is denoted as Sample 1-Modified Calcium Hydroxide.
[0028] 1.2 The preparation process of modified calcium hydroxide is as follows: 1) Calcium hydroxide with a particle size of 0.1~0.15mm was mixed with deionized water at a mass ratio of 1:7 and placed in a hydrothermal reactor for a multi-stage hydrothermal reaction. First, the mixture was heated to 160℃ and sealed for 100min, then heated to 320℃ and sealed for 80min, then heated to 580℃ and sealed for 50min. After cooling to room temperature, the mixture was centrifuged and filtered, and then vacuum dried at 90~95℃ for 1.5h to obtain hydrated activated calcium hydroxide. 2) Mix silica with a silicon coupling agent and grind for 20 minutes. The amount of silicon coupling agent is 0.5% of the mass of silica. Then add hydrated activated calcium hydroxide and sodium silicate and continue grinding until the particle size is less than 0.2 μm. The amount of silica is 7.2% of the mass of calcium hydroxide and the amount of sodium silicate is 6.8% of the mass of silica. Modified calcium hydroxide is obtained and is denoted as Sample 2-Modified Calcium Hydroxide.
[0029] 1.3 The preparation process of modified calcium hydroxide is as follows: 1) Calcium hydroxide with a particle size of 0.1~0.15mm was mixed with deionized water at a mass ratio of 1:8 and placed in a hydrothermal reactor for a multi-stage hydrothermal reaction. First, the mixture was heated to 155℃ and sealed for 110 min, then heated to 350℃ and sealed for 90 min, then heated to 590℃ and sealed for 40 min. After cooling to room temperature, the mixture was centrifuged and filtered, and then vacuum dried at 90~95℃ for 2 h to obtain hydrated activated calcium hydroxide. 2) Mix silica with a silicon coupling agent and grind for 30 minutes. The amount of silicon coupling agent is 0.1% of the mass of silica. Then add hydrated activated calcium hydroxide and sodium silicate and continue grinding until the particle size is less than 0.2 μm. The amount of silica is 6.4% of the mass of calcium hydroxide and the amount of sodium silicate is 5% of the mass of silica. Modified calcium hydroxide is obtained and is denoted as Sample 3-Modified Calcium Hydroxide.
[0030] Example 2: Preparation of an oxidizing activated carbon 2.1 The preparation process of oxidizing activated carbon is as follows: Particles with a diameter of 0.2~0.3mm and a specific surface area of 950~1050m² are prepared... 2 / g of activated carbon was washed with water, boiled, and dried, then soaked in a 15 (w / w)% hydrogen peroxide solution at a ratio of 100g:500ml. The soaking temperature was 40℃ and the soaking time was 4.5h. During the soaking process, ozone was introduced for synergistic treatment at a rate of 8mg / L for 3h. After the ozone synergistic treatment ended, the carbon was soaked for another 0.5h, then filtered, washed, and dried to obtain oxidized activated carbon, denoted as 1-oxidized activated carbon.
[0031] 2.2 The preparation process of oxidizing activated carbon is as follows: Particles with a diameter of 0.2~0.3mm and a specific surface area of 950~1050m² are prepared... 2 / g of activated carbon was washed with water, boiled, and dried, then soaked in a 20 (w / w)% hydrogen peroxide solution at a ratio of 100g:400ml. The soaking temperature was 50℃, and the soaking time was 3.5h. During the soaking process, ozone was introduced for synergistic treatment at a rate of 6mg / L for 2h. After the ozone synergistic treatment ended, the carbon was soaked for another 0.5h, then filtered, washed, and dried to obtain oxidized activated carbon, denoted as 2-oxidized activated carbon.
[0032] Example 3: Preparation of a Modified Activated Carbon 3.1 The preparation process of modified activated carbon is as follows: a. Dissolve ferric nitrate and magnesium nitrate in anhydrous ethanol to form a metal ion solution with a total metal ion concentration of 0.12 mol / L and a molar ratio of ferric ions to magnesium ions of 1.4:1. Then add citric acid with a molar ratio of citric acid to total metal ions of 1.2:1. Stir until the solution is transparent, and then adjust the pH to 5-6 to obtain a transparent sol. b. Add the oxidized activated carbon from Example 2.2 to the transparent sol, stir evenly, sonicate at 450W for 30 minutes, stir at 800rpm for 5 hours, and vacuum dry at 85~90℃ for 2 hours to obtain a solid matrix. c. Heat-treat the solid matrix by heating it to 420℃ at a rate of 2℃ / min and holding it for 2.5h to obtain modified activated carbon, denoted as Sample 1-modified activated carbon. In Sample 1-modified activated carbon, the amount (w / w) of the supported iron oxide Fe2O3 is 7.11%, and the amount (w / w) of the supported magnesium oxide MgO is 2.56%.
[0033] 3.2 The preparation process of modified activated carbon is as follows: a. Dissolve ferric nitrate and magnesium nitrate in ethanol to form a metal ion solution with a total metal ion concentration of 0.13 mol / L and a molar ratio of ferric ions to magnesium ions of 1.6:1. Then add citric acid with a molar ratio of citric acid to total metal ions of 1.3:1. Stir until the solution is transparent, and then adjust the pH to 5-6 to obtain a transparent sol. b. Add the oxidized activated carbon from Example 2.2 to the above transparent sol, stir evenly, sonicate at 500W for 35 minutes, stir at 900rpm for 4 hours, and vacuum dry at 85~90℃ for 2.5 hours to obtain a solid matrix. c. Heat-treat the solid matrix by heating it to 430℃ at a rate of 3℃ / min and holding it for 3h to obtain modified activated carbon, denoted as Sample 2-modified activated carbon. The amount (w / w) of iron oxide Fe2O3 loaded in Sample 2-modified activated carbon is 7.58%, and the amount (w / w) of magnesium oxide MgO loaded is 2.39%.
[0034] 3.3 The preparation process of modified activated carbon is as follows: a. Dissolve ferric nitrate and magnesium nitrate in anhydrous ethanol to form a metal ion solution with a total metal ion concentration of 0.12~0.14 mol / L. Then add citric acid with a molar ratio of citric acid to total metal ions of 1.2~1.5:1. Stir until the solution is transparent, and then adjust the pH to 5~6 to obtain a transparent sol. b. Add the oxidized activated carbon from Example 2.2 to the transparent sol, stir evenly, sonicate at 450-500W for 30-35 minutes, stir at 800-1000rpm for 3-5 hours, and vacuum dry at 85-90℃ for 2-3 hours to obtain a solid matrix. c. Heat-treat the solid matrix by raising the temperature to 420-450℃ at a rate of 2-5℃ / min and holding it for 2-3 hours to obtain modified activated carbon, denoted as Sample 3-Modified Activated Carbon. The amount (w / w) of iron oxide Fe2O3 loaded in Sample 3-Modified Activated Carbon is 7.95%, and the amount (w / w) of magnesium oxide MgO loaded is 2.23%.
[0035] Example 4: A calcium-based desulfurizing agent and its preparation method A calcium-based desulfurizing agent comprises the following raw materials by mass percentage: Sample 1 - modified calcium hydroxide 53%, Sample 2 - modified activated carbon 27%, sodium carbonate 8%, metal oxide 5%, and composite binder 7%; The metal oxide is composed of aluminum oxide, cerium oxide and copper oxide in a mass ratio of 3.5:1:2, and the composite adhesive is composed of silica sol and sodium tripolyphosphate in a mass ratio of 3:1, with the silica sol containing 20% nano-silica. The preparation method of this desulfurizing agent includes the following steps: Step 1: Weigh 106g of modified calcium hydroxide, 54g of modified activated carbon, 16g of sodium carbonate, and 10g of metal oxide according to the above mass percentages, and mix them evenly to form solid mixture A. Step 2: Add 19g of water to the solid mixture A and stir to moisten it. Then add 14g of composite adhesive and stir evenly. Granulate to obtain a semi-finished product. Step 3: Place the semi-finished product in a steam environment at 220℃ and 0.2MPa for 1.5h, and then dry it at 110~120℃ to obtain calcium-based desulfurizer.
[0036] Example 5: A calcium-based desulfurizing agent and its preparation method A calcium-based desulfurizing agent comprises the following raw materials by mass percentage: 56% modified calcium hydroxide (sample 2), 25% modified activated carbon (sample 3), 6% sodium carbonate, 3% metal oxide, and 10% composite binder; The metal oxide is composed of aluminum oxide, cerium oxide and copper oxide in a mass ratio of 3.5:1:2, and the composite adhesive is composed of silica sol and sodium tripolyphosphate in a mass ratio of 3:1, with the silica sol containing 20% nano-silica. The preparation method of this desulfurizing agent includes the following steps: Step 1: Mix 112g of modified calcium hydroxide (Sample 2), 50g of modified activated carbon (Sample 3), 12g of sodium carbonate, and 6g of metal oxide evenly to form solid mixture A; Step 2: Add 27g of water to the solid mixture A and stir to moisten it. Then add 20g of composite adhesive and stir evenly. Granulate to obtain a semi-finished product. Step 3: Place the semi-finished product in a steam environment at 240℃ and 0.6MPa for 2 hours, and then dry it at 110~120℃ to obtain calcium-based desulfurizer.
[0037] Example 6: A calcium-based desulfurizing agent and its preparation method A calcium-based desulfurizing agent comprises, by mass percentage, the following raw materials: 61% modified calcium hydroxide (sample 3), 23% modified activated carbon (sample 1), 4% sodium carbonate, 4% metal oxide, and 8% composite binder; The metal oxide is composed of aluminum oxide, cerium oxide and copper oxide in a mass ratio of 3.5:1:2, and the composite adhesive is composed of silica sol and sodium tripolyphosphate in a mass ratio of 3:1, with the silica sol containing 20% nano-silica. The preparation method of this desulfurizing agent includes the following steps: Step 1: Mix 122g of sample 3-modified calcium hydroxide, 46g of sample 1-modified activated carbon, 8g of sodium carbonate, and 8g of metal oxide evenly to form solid mixture A; Step 2: Add 23g of water to the solid mixture A and stir to moisten it. Then add 16g of composite adhesive and stir evenly. Granulate to obtain a semi-finished product. Step 3: Place the semi-finished product in a steam environment at 250℃ and 0.3MPa for 1 hour, and then dry it at 110~120℃ to obtain calcium-based desulfurizer.
[0038] Example 7: A calcium-based desulfurizing agent and its preparation method The difference between the calcium-based desulfurizing agent and its preparation method and Example 5 is that the metal oxide is composed of aluminum oxide, cerium oxide and copper oxide in a mass ratio of 4:1:3, the composite binder is composed of silica sol and sodium tripolyphosphate in a mass ratio of 3.5:1, and the content of nano-silica in the silica sol is 25%.
[0039] Example 8: A calcium-based desulfurizing agent and its preparation method The calcium-based desulfurizing agent and its preparation method differ from those in Example 5 in that: the metal oxide is composed of aluminum oxide, cerium oxide and copper oxide mixed in a mass ratio of 4.5:1:2.5, the composite binder is composed of silica sol and sodium tripolyphosphate mixed in a mass ratio of 4:1, and the content of nano-silica in the silica sol is 23%.
[0040] Example 9: A calcium-based desulfurizing agent and its preparation method The difference between the calcium-based desulfurizing agent and its preparation method and Example 5 is that the metal oxide is made by mixing aluminum oxide and cerium oxide in a mass ratio of 3.5:1.
[0041] Example 10: A calcium-based desulfurizing agent and its preparation method The difference between the calcium-based desulfurizing agent and its preparation method and Example 5 is that the metal oxide is made by mixing aluminum oxide and copper oxide in a mass ratio of 3.5:2.
[0042] Example 11: A calcium-based desulfurizing agent and its preparation method The difference between the calcium-based desulfurizing agent and its preparation method and Example 5 is that the metal oxide is composed of cerium oxide and copper oxide mixed in a mass ratio of 1:2.
[0043] Comparative Example 1: A calcium-based desulfurizing agent and its preparation method The difference between the calcium-based desulfurizing agent and its preparation method and Example 5 is that: nano-calcium hydroxide replaces sample 2-modified calcium hydroxide.
[0044] Comparative Example 2: A calcium-based desulfurizing agent and its preparation method The difference between the calcium-based desulfurizing agent and its preparation method and Example 5 is as follows: The preparation process of modified calcium hydroxide is as follows: calcium hydroxide with a particle size of 0.1~0.15mm is mixed with deionized water at a mass ratio of 1:7 and placed in a hydrothermal reactor for hydrothermal reaction. The mixture is heated to 160℃ and sealed for 240min. After cooling to room temperature, it is centrifuged and filtered, and then vacuum dried at 90~95℃ for 1.5h to obtain modified calcium hydroxide, which replaces sample 2-modified calcium hydroxide in Example 5.
[0045] Comparative Example 3: A calcium-based desulfurizing agent and its preparation method The difference between the calcium-based desulfurizing agent and its preparation method and Example 5 is as follows: The preparation process of modified calcium hydroxide is as follows: silica and silicon coupling agent are mixed and ground for 20 minutes. The amount of silicon coupling agent is 0.5% of the mass of silica. Then, calcium hydroxide with a particle size of 0.1~0.15 mm is added and ground until the particle size is less than 0.2 μm. The amount of silica is 7.2% of the mass of calcium hydroxide. Modified calcium hydroxide is obtained, which replaces Sample 2-modified calcium hydroxide in Example 5.
[0046] Comparative Example 4: A calcium-based desulfurizing agent and its preparation method The difference between the calcium-based desulfurizing agent and its preparation method in Example 5 is that the preparation process of modified calcium hydroxide is as follows: 1) Calcium hydroxide with a particle size of 0.1~0.15mm was mixed with deionized water at a mass ratio of 1:7 and placed in a hydrothermal reactor for a multi-stage hydrothermal reaction. The mixture was heated to 160℃ and sealed for 100min, then heated to 420℃ and sealed for 90min. After cooling to room temperature, the mixture was centrifuged and filtered, and then vacuum dried at 90~95℃ for 1.5h to obtain hydrated activated calcium hydroxide. 2) Mix silica with a silicon coupling agent and grind for 20 minutes. The amount of silicon coupling agent is 0.5% of the mass of silica. Then add hydrated activated calcium hydroxide and continue grinding until the particle size is less than 0.2 μm. The amount of silica is 7.2% of the mass of calcium hydroxide to obtain modified calcium hydroxide, which replaces sample 2-modified calcium hydroxide in Example 5.
[0047] Comparative Example 5: A calcium-based desulfurizing agent and its preparation method The calcium-based desulfurizing agent and its preparation method differ from those in Example 5 in that: the particle size is 0.2~0.3mm and the specific surface area is 950~1050m². 2 / g of activated carbon replaces sample 3-modified activated carbon in Example 5.
[0048] Comparative Example 6: A calcium-based desulfurizing agent and its preparation method The calcium-based desulfurizing agent and its preparation method differ from those in Example 5 in that: the particle size is 0.2~0.3mm and the specific surface area is 950~1050m². 2 / g activated carbon replaces sample 3-modified activated carbon in Example 5, and the activated carbon mass fraction is 22.5%, the metal oxide mass fraction is 5.5%, and the metal oxide is a mixture of aluminum oxide, cerium oxide, copper oxide, ferric oxide and magnesium oxide in a mass ratio of 3.5:1:2:4.5:1.
[0049] Comparative Example 7: A calcium-based desulfurizing agent and its preparation method The difference between the calcium-based desulfurizing agent and its preparation method and Example 5 is that the metal oxide is only aluminum oxide.
[0050] Comparative Example 8: A calcium-based desulfurizing agent and its preparation method The difference between the calcium-based desulfurizing agent and its preparation method and Example 5 is that the metal oxide is only cerium oxide.
[0051] Comparative Example 9: A calcium-based desulfurizing agent and its preparation method The difference between the calcium-based desulfurizing agent and its preparation method and Example 5 is that the metal oxide is only copper oxide.
[0052] Comparative Example 10: A calcium-based desulfurizing agent and its preparation method The calcium-based desulfurizing agent and its preparation method differ from those in Example 5 in that: silica sol replaces the composite binder, and the content of nano-silica in the silica sol is 20%.
[0053] Comparative Example 11: A calcium-based desulfurizing agent and its preparation method The difference between the calcium-based desulfurizing agent and its preparation method in Example 5 is that sodium tripolyphosphate is used instead of the composite adhesive.
[0054] Comparative Example 12: A calcium-based desulfurizing agent and its preparation method The difference between the calcium-based desulfurizer and its preparation method in Example 5 is that sodium carboxymethyl cellulose is used instead of the composite adhesive.
[0055] Comparative Example 13: A calcium-based desulfurizing agent and its preparation method The calcium-based desulfurizing agent and its preparation method differ from those in Example 5 in that the composite adhesive is made by mixing silica sol and sodium carboxymethyl cellulose in a mass ratio of 3:1, and the content of nano-silica in the silica sol is 20%.
[0056] Comparative Example 14: A calcium-based desulfurizing agent and its preparation method The difference between the calcium-based desulfurizer and its preparation method and Example 5 is that: in step 3, the semi-finished product is dried at a temperature of 110~120℃ to obtain the calcium-based desulfurizer.
[0057] The calcium-based desulfurizing agents prepared in Examples 4-11 and Comparative Examples 1-14 were subjected to corresponding performance tests, and the performance results are shown in Table 1.
[0058] Compressive strength (N / cm): The load-bearing capacity of the calcium-based desulfurizer sample under mechanical pressure was determined by applying pressure to the sample using a pressure testing machine.
[0059] Sulfur capacity (%): The sulfur capacity of flue gas was tested in accordance with HG / T 2513-2014.
[0060] Desulfurization efficiency: Simulated coking flue gas test, temperature: 220℃, SO2: 1800mg / m³ 3 NOx: 750 mg / m³ 3 CO2: 8%, O2: 6%, H2O: 15%, reaction space velocity 2000 h⁻¹ -1 Desulfurization efficiency was tested after 60 hours. Desulfurization efficiency (%) = (Total SO2 content in raw gas - Total SO2 content in tail gas) / (Total SO2 content in raw gas) × 100%. Cumulative effective desulfurization test duration: Each calcium-based desulfurizer product was used to treat the simulated coking flue gas multiple times. The SO2 concentration reached 30 mg / m³ in each treatment. 3 If the SO2 concentration does not change, stop the process, record the desulfurization time, and accumulate all the effective desulfurization times of each calcium-based desulfurizer to obtain the cumulative effective desulfurization test time (h) of each calcium-based desulfurizer.
[0061] Table 1 Performance Results
[0062] As shown in Table 1, the calcium-based desulfurizer prepared by this invention using modified calcium hydroxide, modified activated carbon, alkali metal compounds, metal oxides, and composite binders as raw materials has high compressive strength, high sulfur capacity, high desulfurization rate, and long cumulative effective desulfurization test time. This results in a calcium-based desulfurizer with high compressive strength and a porous structure, which effectively enhances the adsorption capacity and reactivity of the calcium-based desulfurizer. This prevents the calcium-based desulfurizer from having its pores blocked by the produced calcium sulfate, thus improving the desulfurization effect in the later stages, increasing the removal efficiency of SO2 in flue gas, and also improving its own utilization rate.
[0063] In summary, the calcium-based desulfurizer prepared by this invention has high activity, which can improve its removal efficiency of SO2 in flue gas and increase its utilization rate.
[0064] It will be apparent to those skilled in the art that the present invention is not limited to the details of the exemplary embodiments described above, and that the invention can be implemented in other specific forms without departing from its spirit and essential characteristics. Therefore, the embodiments should be considered in all respects as exemplary and non-limiting, and the scope of the invention is defined by the appended claims rather than the foregoing description. Thus, it is intended that all variations falling within the meaning and scope of equivalents of the claims be included within the present invention.
[0065] Furthermore, it should be understood that although this specification describes embodiments, not every embodiment contains only one independent technical solution. This narrative style is merely for clarity. Those skilled in the art should consider the specification as a whole, and the technical solutions in each embodiment can also be appropriately combined to form other embodiments that can be understood by those skilled in the art.
Claims
1. A calcium-based desulfurizing agent, characterized in that, The raw materials for preparation, by mass percentage, are: 53-61% modified calcium hydroxide, 22-27% modified activated carbon, 4-8% alkali metal compounds, 3-5% metal oxides, and 7-10% composite binder; The modified calcium hydroxide is obtained by modifying calcium hydroxide through multi-stage hydrothermal reaction and treatment with silicon dioxide and sodium silicate; The modified activated carbon is an oxidizing activated carbon loaded with iron oxide and magnesium oxide.
2. The calcium-based desulfurizer according to claim 1, characterized in that, The metal oxide is a mixture composed of aluminum oxide, cerium oxide and copper oxide.
3. The calcium-based desulfurizer according to claim 2, characterized in that, In metal oxides, the mass ratio of aluminum oxide, cerium oxide and copper oxide is 3.5~4.5:1:2~3.
4. The calcium-based desulfurizer according to claim 1, characterized in that, The composite adhesive is a mixture of silica sol and sodium tripolyphosphate, and the content of nano-silica in the silica sol is 20-25%.
5. The calcium-based desulfurizer according to claim 4, characterized in that, In the composite adhesive, the mass ratio of silica sol to sodium tripolyphosphate is 3~4:
1.
6. The calcium-based desulfurizer according to claim 1, characterized in that, The preparation process of the modified calcium hydroxide: 1) Mix calcium hydroxide with deionized water and place it in a hydrothermal reactor for a multi-stage hydrothermal reaction. First, heat to 150~160℃ and react in a sealed container for 100~120 min. Then, continue heating to 320~350℃ and react in a sealed container for 70~90 min. Then, continue heating to 580~600℃ and react in a sealed container for 30~50 min. Cool to room temperature, centrifuge and filter, and dry under vacuum at 90~95℃ for 1~2 h to obtain hydrated activated calcium hydroxide. 2) Mix silica with silicon coupling agent and grind for 20-30 minutes, then add hydrated activated calcium hydroxide and sodium silicate and continue grinding until the particle size is less than 0.2 μm to obtain modified calcium hydroxide.
7. A calcium-based desulfurizing agent according to claim 6, characterized in that, In step 3), the amount of silicon coupling agent is 0.5-1% of the mass of silicon dioxide; the amount of silicon dioxide is 5.8-7.2% of the mass of calcium hydroxide; and the amount of sodium silicate is 5-8% of the mass of silicon dioxide.
8. The calcium-based desulfurizer according to claim 1, characterized in that, The modified activated carbon preparation process: a. Dissolve ferric nitrate and magnesium nitrate in ethanol to form a metal ion solution with a total metal ion concentration of 0.12~0.14 mol / L. Then add citric acid, with a molar ratio of citric acid to total metal ions of 1.2~1.5:
1. Stir until the solution is transparent, and then adjust the pH to 5~6 to obtain a transparent sol. b. Add oxidized activated carbon to the above transparent sol, stir evenly, sonicate at 450~500W for 30~35min, stir at 800~1000rpm for 3~5h, and vacuum dry at 85~90℃ for 2~3h to obtain a solid matrix. c. Heat-treat the solid matrix by raising the temperature to 420-450℃ at a rate of 2-5℃ / min and holding it at that temperature for 2-3 hours to obtain modified activated carbon.
9. A calcium-based desulfurizing agent according to claim 8, characterized in that, The molar ratio of iron ions to magnesium ions in step a is 1.4~1.8:1; The oxidized activated carbon mentioned in step b is obtained by treating activated carbon with hydrogen peroxide and ozone; In step c, the iron oxide loading in the modified activated carbon is 7-8%.
10. A method for preparing the calcium-based desulfurizing agent according to claim 1, characterized in that, Includes the following steps: Step 1: Mix modified calcium hydroxide, modified activated carbon, alkali metal compound, and metal oxide evenly to form solid mixture A; Step 2: Add water to the solid mixture A and stir to wet it. The amount of water is 10-15% of the solid mixture A. Then add the composite adhesive and stir evenly. Granulate to obtain a semi-finished product. Step 3: Place the semi-finished product in a steam environment at a temperature of 220~250℃ and a pressure of 0.2~0.3MPa for 1~2 hours, and then dry it at a temperature of 110~120℃ to obtain calcium-based desulfurizer.