A method for preparing a dry desulfurizing agent resistant to high-temperature flue gas

Abstract

This invention relates to the field of desulfurizing agent technology, specifically disclosing a method for preparing a dry desulfurizing agent resistant to high-temperature flue gas. This desulfurizing agent, while ensuring the removal effect of SO2, HCl and dioxins, achieves chemical bonding between functional components as the core and active CaCO3 as the coating layer through co-precipitation method. This results in tight bonding between components, ensuring that the desulfurizing agent particles are not easily broken or pulverized during high-temperature airflow scouring and mutual friction, reducing fly ash. Combined with the multi-level porous structure constructed during the preparation process, it solves the problem that existing dry desulfurizing agents are fragile and cannot be fully utilized during use.

Description

Technical Field

[0001] This invention belongs to the field of desulfurizing agents, specifically relating to a method for preparing a dry desulfurizing agent resistant to high-temperature flue gas, which is particularly suitable for the synergistic and efficient removal of hydrogen chloride, sulfur dioxide and dioxins from high-temperature flue gas (800-900℃) generated by incinerating municipal solid waste. Background Technology

[0002] With the acceleration of urbanization and the continuous improvement of residents' living standards, the amount of municipal solid waste generated has increased dramatically. The emission of flue gas pollutants (especially dioxins, heavy metals, and acidic gases) during the incineration process has become a key factor causing serious environmental problems. Persistent organic pollutants such as dioxins are major contributors to soil and water pollution, food chain toxicity, carcinogenic and teratogenic risks, and disruption of the human endocrine system. To address increasingly severe environmental challenges and tightening environmental regulations, developing and applying efficient and economical flue gas purification technologies has become a consensus and core task for the global environmental protection industry, particularly in waste-to-energy incineration, solid waste treatment, and hazardous waste disposal.

[0003] Traditional semi-dry desulfurization processes (such as spray drying absorption of SDA) typically require the addition of large amounts of slaked lime (Ca(OH)2) as an absorbent to neutralize acidic gases in the flue gas. However, excessive lime usage significantly increases fly ash production, not only burdening subsequent dust removal equipment but also raising the treatment costs of hazardous waste (fly ash). Therefore, developing dry desulfurization agents that can replace or reduce lime usage while efficiently removing multiple pollutants has become an urgent need for cost reduction and efficiency improvement in the waste incineration industry.

[0004] Patent CN112717677A discloses a dry desulfurizing agent with good dispersibility and its preparation method. It combines activated carbon with copper oxide and adds NaHCO3 as a thermal activation aid. NaHCO3 decomposes instantaneously into Na2CO3 in flue gas at 120-180℃, which increases the specific surface area and improves the adsorption rate by explosively creating pores. However, the desulfurizing agent prepared by this method has low mechanical strength, and the particles are simply dry-mixed and easily broken into fine powder after spraying. Patent CN115888347A uses 40-80% converter mud (Fe2O3, CaO, MnO, etc.) as active aggregate, combined with 10-30% Ca(OH)2, 1-10% metal oxides (CuO / MnO2), 1-5% cellulose, and 1-5% polymer binder. Cellulose acts as a low-temperature binder and granulator, leaving 0.1-0.5μm-sized through-pores after carbonization above 300℃, resulting in particle strength greater than 60N. MnO2 provides active oxygen, which can oxidize SO2 to sulfate in situ. Although this method can achieve a 98% desulfurization rate at 60℃, when the flue gas temperature exceeds 180℃, MnO2 begins to thermally decompose and lose oxygen, causing a sharp drop in sulfur capacity, making it difficult to directly apply to high-temperature flue gas purification scenarios.

[0005] In addition to the aforementioned problems, current dry desulfurizing agents also suffer from the issue of a calcium sulfate product layer forming on the surface of unreacted calcium carbonate particles, hindering further reaction of the internal desulfurizing agent and resulting in insufficient utilization of the agent. Therefore, there is an urgent need in the market for a desulfurizing agent that can maintain structural stability, has tight bonding between components, and high utilization rate under high-temperature flue gas conditions. Summary of the Invention

[0006] To overcome the shortcomings of the prior art, this invention achieves chemical bonding between the functional component as the core and the active CaCO3 as the coating layer through co-precipitation, resulting in a tight bond between the components and ensuring that the desulfurizer particles are not easily broken or pulverized during high-temperature airflow scouring and mutual friction. Furthermore, the hierarchical porous structure constructed during the preparation process facilitates the diffusion of flue gas into the interior and the solid-state ion migration of the reaction product CaSO4, mitigating the problem of reduced desulfurizer utilization caused by product layer blockage.

[0007] To achieve the above objectives, the technical solution adopted by the present invention is as follows: This invention provides a method for preparing a dry desulfurizing agent resistant to high-temperature flue gas, comprising the following preparation steps: S1. The functional components are ball-milled with ball milling beads at a speed of 100-300 rpm for 1-3 hours, and a supported catalyst is added to obtain powder; the powder is granulated with deionized water to obtain core particles of 50-100 μm. S2. Add the core particles to deionized water, and add the pre-prepared CaCl2 solution and Na2CO3 solution at 250-350 rpm and 55-65℃. Add both simultaneously over 4-5 hours, then continue stirring for 1-2 hours. Then stop heating and stirring, let stand for 30-60 minutes, wash, and obtain the precipitate. S3. Dry the precipitate at 60-80℃, and then increase the temperature by a programmed process to obtain a dry desulfurizing agent resistant to high-temperature flue gas. The dry desulfurizing agent provided by this invention is particularly suitable for high-temperature flue gas (800-900℃) generated by municipal solid waste incinerators. Within this temperature range, the calcium carbonate shell in the desulfurizing agent rapidly decomposes into highly active CaO, while the supported catalyst within the core rapidly catalyzes the oxidation of dioxins and SO2. Furthermore, this desulfurizing agent can partially replace the large amounts of slaked lime used in traditional semi-dry processes, reducing lime consumption by 30%-50%, thereby significantly reducing fly ash generation and alleviating the pressure on subsequent fly ash treatment.

[0008] In step S1, the functional components, by mass percentage (100%), include 10-20% high specific surface area activated carbon, 5-10% carbon powder, 5-10% calcium hydroxide, 20-30% bentonite, 8-15% talc, 5-10% starch, 3-8% alumina, 8-15% kaolin, and 2-5% nano titanium dioxide.

[0009] This invention provides a desulfurizer with a core-shell structure. Firstly, the desulfurizer uniformly and densely coats CaCO3 in microcrystalline form on its surface, forming a complete calcium carbonate shell that directly serves as a reaction interface to chemically react with SO2 in high-temperature flue gas (≥300℃), thereby increasing the reaction rate. Secondly, the alumina, kaolin, talc, and other materials used in the core form a stable physical framework during high-temperature processes and downstream applications in high-temperature flue gas, preventing overall structural collapse. Thirdly, a co-precipitation method achieves chemical bonding between the highly stable core and the active CaCO3 coating layer, ensuring that the desulfurizer particles are not easily broken or pulverized during the scouring and friction of high-temperature flue gas flow. Fourthly, the constructed hierarchical porous structure facilitates the diffusion of high-temperature flue gas into the interior and the migration of solid ions from the reaction product CaSO4, mitigating the desulfurizer passivation phenomenon caused by product layer blockage.

[0010] In the functional components: carbon powder and starch generate gas when exposed to high-temperature flue gas. After escaping, the gas leaves abundant channels within the core, forming an initial macroporous network that facilitates gas diffusion into the deeper particles. Bentonite possesses excellent viscosity and plasticity, aiding in the granulation of core particles. Its layered silicate structure removes interlayer water at high temperatures and may undergo structural reorganization, forming stable micropores and mesopores. These pores increase the internal surface area and provide additional pathways for gas transport. Calcium hydroxide preferentially reacts rapidly with HCl in the flue gas, protecting CaCO3 and ensuring it is dedicated to SO2 removal, preventing HCl from competing with CaCO3 for the same reaction, which would lead to a decrease in sulfur capacity. High specific surface area activated carbon provides adsorption sites, increasing dioxin adsorption capacity. Nano-titanium dioxide generates active oxygen at a flue gas temperature of 300℃, catalytically oxidizing adsorbed dioxins into CO2, H2O, and trace amounts of HCl, avoiding saturation failure caused by simple adsorption. Talc powder maintains structural stability under high-temperature calcination and desulfurization operating temperatures. As dispersed hard points or a framework, it works synergistically with alumina to resist high-temperature sintering and densification, ensuring the hierarchical porous system does not collapse during long-term use. It effectively inhibits the thermal shrinkage and deformation of the core structure, thus helping to maintain the stability of the pore structure. Furthermore, its natural lubricity helps improve the processing performance of the mixture, resulting in more uniform granulation. Kaolin and bentonite synergistically provide viscosity, while synergistically with talc powder and alumina as an inert framework. Their cost advantage allows for effective cost reduction without sacrificing performance.

[0011] In some embodiments, the bentonite is calcium-based bentonite.

[0012] Calcium-based bentonite is preferred over sodium-based bentonite to avoid the introduction of alkaline sodium metal, which is detrimental to subsequent desulfurization reactions.

[0013] In some embodiments, in step S1, the mass ratio of the powder to water is approximately 1:(0.2 to 0.5).

[0014] In some embodiments, in step S1, the mass ratio of the functional component to the supported catalyst is 1:(0.02 to 0.08).

[0015] In some embodiments, the preparation steps of the supported catalyst in step S1 are as follows: Ferric nitrate nonahydrate was dissolved in anhydrous ethanol to obtain a precursor solution. The precursor solution was added to a mesoporous silica support and stirred for 15–30 min. After drying, the temperature was increased to 380–420 °C at a rate of 1–3 °C / min and held for 3–5 h to obtain the supported catalyst.

[0016] In some embodiments, the ratio of the precursor solution to the carrier mesoporous silica is 1 mL: (0.8–1.2) g.

[0017] Iron oxide can catalyze the oxidation of SO2 to SO3, and SO3 can react more quickly with CaO to form stable CaSO4, thereby accelerating the desulfurization reaction kinetics. In the supported catalyst provided by this invention, iron oxide grows in a confined space within the regular pores of the support, forming nanoparticles with a size typically smaller than the pore size of the support. Their dispersion is much higher than that of directly added iron oxide powder, effectively preventing catalyst agglomeration. Each of the supported iron oxide nanoparticles can serve as a catalytic active site, allowing a very small amount of iron oxide to provide a large effective reaction interface. Furthermore, the support itself has excellent thermal stability and open pores, serving not only as a scaffold for the nano-iron oxide but also adding extra mesoporous volume to the core, further optimizing the overall hierarchical porous structure of the desulfurizer and ensuring the long-term stability of the catalyst's active components under high-temperature flue gas conditions.

[0018] In some embodiments, in step S2, the ratio of the core particles to deionized water is 1g:70-100mL.

[0019] In some embodiments, in step S2, the molar ratio of CaCl2 in the CaCl2 solution to Na2CO3 in the Na2CO3 solution is 1:(1.0 to 1.3).

[0020] In some embodiments, in step S3, the programmed temperature rise specifically comprises: stage one, raising the temperature from room temperature to 280-320°C at a rate of 3-8°C / min and holding for 1-2 hours; stage two, raising the temperature to 450-520°C at a rate of 3-8°C / min and holding for 1-3 hours; and stage three, allowing the furnace to cool naturally to room temperature.

[0021] This invention constructs a hierarchical porous (macropore-mesopore-micropore) system through programmed temperature rise. During this process, starch and carbon powder decompose into gases and escape, leaving a large number of interconnected macropores inside the material. Furthermore, the formation of the internal framework can inhibit the excessive growth of calcium carbonate grains and the collapse of pores, thus preserving the mesopore and micropore structures. At the same time, it ensures that the calcium carbonate shell is partially activated but not sintered, ultimately forming a multi-level porous structure with high thermal stability and conducive to gas diffusion and reaction.

[0022] When subjected to programmed heating, although calcium hydroxide undergoes surface dehydration to form a CaO active layer in stage two, the interior remains calcium hydroxide. This structure actually facilitates the diffusion-reaction of HCl. High-surface-area activated carbon also experiences a decrease in microporosity due to thermal collapse in stage two. While this reduces adsorption efficiency, the catalytic degradation function of titanium dioxide can compensate for some of the adsorption loss.

[0023] Compared with the prior art, the present invention has the following beneficial effects: 1. This invention provides a dry desulfurizing agent resistant to high-temperature flue gas. It has a core-shell structure, and through chemical bonding between a highly stable core and a CaCO3 coating layer, it can rapidly (with a residence time of 2 seconds) achieve the synergistic removal of HCl, SO2, and dioxins in high-temperature flue gas at 800–900°C, with a removal rate of ≥95% for each. Simultaneously, this desulfurizing agent can replace 30%–50% of the lime used in traditional semi-dry methods, thereby significantly reducing fly ash production and lowering fly ash treatment costs and environmental risks.

[0024] 2. This invention uses multiple functional components as the core of the core-shell structure. Carbon powder and starch generate gas during the heating stage, forming an initial macroporous network. Bentonite's layered silicate structure removes interlayer water at high temperatures, undergoes structural reorganization, and forms stable micropores and mesopores. Kaolinite, talc, and alumina work together as a framework to resist sintering and densification caused by high temperatures, ensuring that the hierarchical porous system does not collapse during long-term use. This effectively inhibits the thermal shrinkage and deformation of the core as a whole, thereby helping to maintain the stability of the pore structure and enabling it to withstand the long-term thermal shock of high-temperature flue gas.

[0025] 3. This invention upgrades iron oxide from a simple additive to a carefully designed structured nanocatalyst. By loading, it not only prevents catalyst agglomeration and improves the dispersibility of the catalyst in the functional components, but also increases the additional mesopore volume, further optimizing the overall hierarchical porous structure of the desulfurizer. This allows the catalyst to improve the overall desulfurization reaction kinetics with low dosage and maintain good catalytic activity at high temperatures. Detailed Implementation

[0026] The present invention will be described below with reference to specific implementation schemes. It should be noted that the following embodiments are examples of the present invention and are used only to illustrate the invention, not to limit it. Other combinations and various modifications within the scope of the present invention can be made without departing from its spirit or scope. It is worth noting that, unless otherwise specified, the raw materials used in the following preparation examples and embodiments can be obtained from any commercially available manufacturer.

[0027] Preparation Example 1 The preparation steps of the supported catalyst are as follows: 10g of ferric nitrate nonahydrate was dissolved in 18mL of anhydrous ethanol to obtain a precursor solution. The precursor solution was added to 18g of mesoporous silica support (SBA-15) and stirred for 30min. After drying at 60℃ for 12h, the temperature was increased to 380-400℃ at a rate of 2℃ / min and held for 4h to obtain the supported catalyst.

[0028] Example 1 A method for preparing a dry desulfurizing agent resistant to high-temperature flue gas includes the following preparation steps: S1. 15.0g of high specific surface area activated carbon, 7.0g of carbon powder, 7.0g of calcium hydroxide, 25.0g of calcium-based bentonite, 12.0g of talc, 6.0g of starch, 6.0g of alumina, 10.0g of kaolin, and 4.0g of nano-titanium dioxide were ball-milled at 200rpm for 2 hours using 200g of 4mm diameter ball milling beads. 4.6g of supported catalyst was added to obtain powder. The powder was then granulated with 34g of deionized water to obtain 75μm core particles. S2. Add deionized water to the core particles at a solid-liquid ratio of 1g:80mL. Add 4.0L of pre-prepared 2 mol / L CaCl2 solution and 4.0L of 2 mol / L Na2CO3 solution at 300rpm and 60℃. Add both simultaneously over 4 hours. Then continue stirring for 1 hour. After that, stop heating and stirring, let stand for 40 minutes, and wash the solid material with clean water until no white precipitate is found when the washing liquid is tested with 0.1 mol / L AgNO3 solution. S3. Dry the precipitate at 70°C for 12 hours, then program the temperature to rise. In the first stage, the temperature is increased from room temperature to 300°C at a rate of 5°C / min and held for 1 hour. In the second stage, the temperature is increased to 500°C at a rate of 5°C / min and held for 2 hours. In the third stage, the temperature is naturally cooled to room temperature with the furnace to obtain a dry desulfurizing agent resistant to high-temperature flue gas.

[0029] Example 2 A method for preparing a dry desulfurizing agent resistant to high-temperature flue gas includes the following preparation steps: S1. 10.0g of high specific surface area activated carbon, 5.0g of carbon powder, 5.0g of calcium hydroxide, 20.0g of calcium-based bentonite, 8.0g of talc, 5.0g of starch, 3.0g of alumina, 8.0g of kaolin, and 2.0g of nano-titanium dioxide were ball-milled at 200rpm for 2 hours using 200g of 4mm diameter ball milling beads. 1.4g of supported catalyst was added to obtain powder. The powder was then granulated with 14g of deionized water to obtain 75μm core particles. S2. Add deionized water to the core particles at a solid-liquid ratio of 1g:70mL. Add 4.0L of pre-prepared 2 mol / L CaCl2 solution and 4.0L of 2 mol / L Na2CO3 solution at 250rpm and 65℃. Add both simultaneously over 4 hours, then continue stirring for 1 hour. After that, stop heating and stirring, let stand for 30 minutes, and wash the solid material until no white precipitate is found when the washing liquid is tested with 0.1 mol / L AgNO3 solution. S3. The precipitate is dried at 60°C for 12 hours, and then the temperature is increased in the following stages: in the first stage, the temperature is increased from room temperature to 320°C at a rate of 8°C / min and held for 1 hour; in the second stage, the temperature is increased to 520°C at a rate of 8°C / min and held for 1 hour; in the third stage, the temperature is naturally cooled to room temperature with the furnace, thus obtaining a dry desulfurizing agent resistant to high-temperature flue gas.

[0030] Example 3 A method for preparing a dry desulfurizing agent resistant to high-temperature flue gas includes the following preparation steps: S1. 20.0g of high specific surface area activated carbon, 10.0g of carbon powder, 10.0g of calcium hydroxide, 30.0g of calcium-based bentonite, 15.0g of talc, 10.0g of starch, 8.0g of alumina, 15.0g of kaolin, and 5.0g of nano-titanium dioxide were ball-milled at 200rpm for 2h using 200g of 4mm diameter ball milling beads. 9.8g of supported catalyst was added to obtain powder. The powder was then granulated with 66g of deionized water to obtain 75μm core particles. S2. Add deionized water to the core particles at a solid-liquid ratio of 1g:100mL. Add 4.0L of pre-prepared 2 mol / L CaCl2 solution and 4.0L of 2 mol / L Na2CO3 solution at 350rpm and 55℃. Add both simultaneously over 5 hours. Then continue stirring for 2 hours. After that, stop heating and stirring and let stand for 60 minutes. Wash the solid material until no white precipitate is found when the washing liquid is tested with 0.1 mol / L AgNO3 solution. The precipitate is obtained. S3. Dry the precipitate at 80°C for 12 hours, then program the temperature to rise. In the first stage, the temperature is increased from room temperature to 280°C at a rate of 3°C / min and held for 2 hours. In the second stage, the temperature is increased to 520°C at a rate of 3°C / min and held for 3 hours. In the third stage, the temperature is naturally cooled to room temperature with the furnace to obtain a dry desulfurizing agent resistant to high-temperature flue gas.

[0031] Example 4 This embodiment provides a method for preparing a dry desulfurizing agent resistant to high-temperature flue gas. The specific implementation method is the same as in Embodiment 1, except that step S3 is adjusted as follows: S3. Dry the precipitate at 70°C for 12 hours, then program the temperature to rise. In the first stage, the temperature is increased from room temperature to 500°C at a rate of 5°C / min and held for 3 hours. In the second stage, the precipitate is naturally cooled to room temperature with the furnace to obtain a dry desulfurizing agent resistant to high-temperature flue gas.

[0032] Comparative Example 1 This comparative example provides a method for preparing a dry desulfurizing agent resistant to high-temperature flue gas. The specific implementation method is the same as in Example 1, except that 2g of supported catalyst is replaced by 0.2g of iron oxide.

[0033] Comparative Example 2 This comparative example provides a method for preparing a dry desulfurizing agent resistant to high-temperature flue gas, comprising the following preparation steps: 15.0g of high specific surface area activated carbon, 7.0g of carbon powder, 7.0g of calcium hydroxide, 25.0g of calcium-based bentonite, 12.0g of talc, 6.0g of starch, 6.0g of alumina, 10.0g of kaolin, and 4.0g of nano titanium dioxide were ball-milled at 200rpm for 2 hours using 200g of 4mm diameter ball milling beads. 4.6g of supported catalyst was added and mixed evenly to obtain a dry desulfurization agent resistant to high-temperature flue gas.

[0034] Performance testing The desulfurizing agents provided in Examples 1-4 and Comparative Examples 1-2 were tested as follows, and the results are shown in Table 1: ① Apparatus: Miniature fixed-bed reactor system (quartz tube with inner diameter of 8-10mm), equipped with multi-channel mass flow meter, electric heating furnace, online flue gas analyzer (SO2, O2, CO2) and temperature control system; ② Test sample: Weigh 5 grams of desulfurizing agent granules (60-80 mesh sieve), put them into the constant temperature zone of the reaction tube, and fix them with quartz wool at the top and bottom; ③ Simulated flue gas composition: 1000 ppm SO2, 500 ppm HCl, 5% O2, 50 ng-TEQ / Nm 3 Dioxins, 10% H2O, with N2 as the equilibrium gas; ④ Step: Under N2 atmosphere, rapidly heat the reaction tube to 850℃ (simulating the high-temperature zone at the outlet of a municipal solid waste incinerator), introduce simulated flue gas, and precisely control the residence time of the flue gas in the reaction tube to 2 seconds by adjusting the total gas flow rate; record the concentrations of SO2, HCl and dioxins at the outlet every 0.5 seconds, and monitor continuously for 10 seconds; calculate the instantaneous removal efficiency at 2 seconds. ⑤ The desulfurization efficiency, dechlorination efficiency and dioxin removal rate were obtained (850℃, 2s).

[0035] Table 1 Performance Test Results

[0036] As shown in Table 1, the desulfurizing agents in Examples 1-3 achieved removal efficiencies of over 95% for SO2, HCl, and dioxins at a high temperature of 850℃ and a very short residence time of only 2 seconds, meeting the requirements for rapid and efficient purification of flue gas from municipal solid waste incineration. Compared with the simple mixed desulfurizing agent in Comparative Example 2, the core-shell structure of this invention significantly improves the reaction rate and utilization rate at high temperatures; compared with the unsupported iron oxide in Comparative Example 1, the supported catalyst maintains higher catalytic activity at high temperatures. Simultaneously, since this desulfurizing agent can replace a large amount of slaked lime used in the traditional semi-dry process, the amount of fly ash generated is significantly reduced, effectively alleviating the pressure on fly ash treatment. In Example 4, due to the lack of segmented temperature programming, particle integrity decreased, resulting in a slight reduction in the removal rate at high temperatures.

[0037] The embodiments and comparative examples described above do not limit the present invention in any way. Although the present invention has been disclosed above with reference to preferred embodiments, it is not intended to limit the present invention. Any person skilled in the art can make some modifications or alterations to the above-disclosed technical content to create equivalent embodiments without departing from the scope of the present invention. Any simple modifications, equivalent changes and alterations made to the above embodiments based on the technical essence of the present invention without departing from the scope of the present invention shall still fall within the scope of the present invention.

Claims

1. A method for preparing a dry desulfurization agent resistant to high-temperature flue gas, characterized in that, The preparation process includes the following steps: S1. The functional components are ball-milled with ball milling beads at a speed of 100-300 rpm for 1-3 hours, and a supported catalyst is added to obtain powder; the powder is granulated with deionized water to obtain core particles of 50-100 μm. S2. Add the core particles to deionized water, and add the pre-prepared CaCl2 solution and Na2CO3 solution at 250-350 rpm and 55-65℃. Add both simultaneously over 4-5 hours, then continue stirring for 1-2 hours. Then stop heating and stirring, let stand for 30-60 minutes, wash, and obtain the precipitate. S3. Dry the precipitate at 60-80℃, and then increase the temperature by a programmed process to obtain a dry desulfurizing agent resistant to high-temperature flue gas. In step S1, the functional components, by mass percentage (100%), include 10-20% high specific surface area activated carbon, 5-10% carbon powder, 5-10% calcium hydroxide, 20-30% bentonite, 8-15% talc, 5-10% starch, 3-8% alumina, 8-15% kaolin, and 2-5% nano titanium dioxide.

2. The preparation method of the dry desulfurizing agent for high-temperature flue gas according to claim 1, characterized in that, The bentonite is calcium-based bentonite.

3. The preparation method of the dry desulfurizing agent for high-temperature flue gas according to claim 2, characterized in that, In step S1, the mass ratio of the powder to water is approximately 1:(0.2 to 0.5).

4. The preparation method of the dry desulfurizing agent for high-temperature flue gas according to claim 1, characterized in that, In step S1, the mass ratio of the functional component to the supported catalyst is 1:(0.02 to 0.08).

5. The method for preparing the dry desulfurizing agent for high-temperature flue gas according to claim 1, characterized in that, In step S1, the preparation steps of the supported catalyst are as follows: ferric nitrate nonahydrate is dissolved in anhydrous ethanol to obtain a precursor solution. The precursor solution is added to the support mesoporous silica and stirred for 15-30 min. After drying, the temperature is raised to 380-420℃ at a rate of 1-3℃ / min and kept at this temperature for 3-5 h to obtain the supported catalyst.

6. The method for preparing the dry desulfurizing agent for high-temperature flue gas according to claim 5, characterized in that, The ratio of the precursor solution to the carrier mesoporous silica is 1 mL: (0.8–1.2) g.

7. The method for preparing the dry desulfurizing agent for high-temperature flue gas according to claim 1, characterized in that, In step S2, the ratio of the core particles to deionized water is 1g:70-100mL.

8. The method for preparing the dry desulfurizing agent for high-temperature flue gas according to claim 1, characterized in that, In step S2, the molar ratio of CaCl2 in the CaCl2 solution to Na2CO3 in the Na2CO3 solution is 1:(1.0~1.3).

9. The method for preparing the dry desulfurizing agent for high-temperature flue gas according to claim 1, characterized in that, In step S3, the programmed temperature rise is specifically as follows: in stage one, the temperature is increased from room temperature to 280-320°C at a rate of 3-8°C / min and held for 1-2 hours; in stage two, the temperature is increased to 450-520°C at a rate of 3-8°C / min and held for 1-3 hours; and in stage three, the furnace is naturally cooled to room temperature.

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