High-specific-surface-area calcium-based flue gas desulfurization absorbent and preparation method thereof

Abstract

The invention belongs to the field of air pollution prevention and inorganic functional materials, and discloses a high-specific-surface-area calcium-based flue gas desulfurization absorbent and a preparation method thereof.The absorbent is prepared from, by weight, 75-88 parts of a calcium-based main body, 5-12 parts of a nanometer silicon-based modifier and 7-13 parts of an organic template agent, and the high-specific-surface-area calcium-based flue gas desulfurization absorbent is prepared by regulating and controlling the proportion of all the components and constructing a hierarchical pore structure. The specific surface area and the desulfurization performance are effectively improved. The preparation method comprises the steps of raw material mixing and dispersing, drying and forming, inert gas protection low-temperature treatment, medium-temperature sintering and vacuum template removal, and cooling and crushing. The specific surface area of the prepared absorbent is not less than 60m / g, the mesopore proportion is not less than 70%, the pore volume is 0.35-0.55 cm / g, the desulfurization efficiency is not less than 95%, and the utilization rate of the absorbent is not less than 80%. The method integrates a composite system and a green process, is excellent in performance and simple in process, and can be industrially applied to flue gas desulfurization of coal-fired power plants and iron and steel industries.

Description

Technical Field

[0001] This invention belongs to the field of air pollution control and inorganic functional materials, specifically relating to a high specific surface area calcium-based flue gas desulfurization absorbent and its preparation method. Background Technology

[0002] Calcium-based absorbents, as key materials in dry or semi-dry flue gas desulfurization technologies, are widely used in industrial practice for SO2 removal due to their abundant sources, low cost, and mature reaction mechanisms. However, traditional calcium-based absorbents generally suffer from problems such as low specific surface area, simple pore structure, poor desulfurization reactivity, insufficient thermal stability, and susceptibility to sintering and clogging. These issues lead to a significant decline in their desulfurization performance after high temperatures or multiple rounds of use, limiting their further engineering applications.

[0003] To improve the overall performance of calcium-based absorbents, existing technologies have explored various material modification and structural control methods. For example, patent CN117018848A discloses an anti-sintering calcium-based absorbent and its preparation method. By introducing Fe2O3 and binders (polyvinyl alcohol, maltodextrin, etc.) into Ca(OH)2, and then performing dry mixing and calcination, the absorbent acquires certain anti-sintering capabilities and an increased specific surface area. This method utilizes industrial solid waste to prepare desulfurizing agents, showing good prospects for resource utilization, and improves the physical structure and reactivity of the absorbent to some extent. However, this approach mainly relies on the spontaneous generation mechanism under high-temperature calcination for pore structure control, limiting the control over micropore size distribution, especially the proportion of mesopores. Furthermore, the material system does not incorporate nanoscale structure-directing agents or surface control mechanisms, limiting the increase in specific surface area and pore volume; the high-temperature, long-duration calcination step during preparation may also lead to high energy consumption. Overall, this technology plays a positive role in improving the anti-sintering performance of absorbents, but there is still room for improvement in constructing hierarchical porous structures and achieving synergistic optimization of specific surface area and desulfurization activity. Summary of the Invention

[0004] To address the shortcomings mentioned in the background section, the present invention aims to provide a high specific surface area calcium-based flue gas desulfurization absorbent and its preparation method. By introducing nano-silicon-based modifiers and organic template agents, a hierarchical porous structure is constructed, significantly improving adsorption performance and anti-sintering ability. Employing a low-energy, integrated preparation process, the material achieves a specific surface area ≥60 m² / g and a mesoporous content ≥70%, effectively solving the problems of low specific surface area, easy clogging, and poor utilization rate of traditional absorbents, making it suitable for high-efficiency industrial flue gas desulfurization applications.

[0005] The objective of this invention can be achieved through the following technical solutions: A high specific surface area calcium-based flue gas desulfurization absorbent comprises the following raw materials in parts by weight: 75-88 parts of calcium-based main body, 5-12 parts of nano-silicon-based modifier, and 7-13 parts of organic template agent. The calcium-based matrix is ​​selected from one or more of calcium oxide, calcium hydroxide, industrial-grade calcium hydroxide micro powder, and light calcium oxide. The nano-silicon-based modifier is selected from one or more of nano-silica, nano-sodium silicate, nano-lithium silicate, and nano-potassium silicate. The organic template agent is selected from one or more of polyethylene glycol-6000, polyethylene glycol-4000, hexadecyltrimethylammonium bromide, and sodium dodecylbenzenesulfonate.

[0006] More preferably, the silicon-calcium molar ratio of the nano-silicon-based modifier to the calcium-based host is 0.05 to 0.2; The high specific surface area calcium-based flue gas desulfurization absorbent has the following physical performance parameters: specific surface area not less than 60 m² / g; mesopore volume fraction not less than 70%, wherein the mesopore diameter is 2-50 nm; and pore volume is 0.35-0.55 cm³ / g. The high specific surface area calcium-based flue gas desulfurization absorbent has a desulfurization efficiency of not less than 95% and an absorbent utilization rate of not less than 80%.

[0007] More preferably, the nano-silicon-based modifier has a particle size of 20–50 nm, a purity of not less than 99.5%, and a specific surface area of ​​150–200 m² / g; When the nano-silicon-based modifier is nano-sodium silicate, its synthesis method includes the following steps: (1) Add industrial grade sodium silicate to deionized water to prepare a solution with a mass concentration of 10-15%; (2) Disperse the ultrasonically in an ultrasonic device at a power of 300-400 W for 30-40 min; (3) Nano-sized sodium silicate particles were obtained by spray drying at 180-220°C.

[0008] More preferably, the organic template agent is polyethylene glycol-6000, with a molecular weight of 5800-6200 and a solubility in water at 25°C ≥100g / L.

[0009] More preferably, when the calcium-based matrix is ​​calcium oxide, it needs to undergo hydration treatment; the hydration treatment method of calcium oxide includes: mixing calcium oxide and deionized water at a mass ratio of 1:3 to 1:4, stirring and reacting at 25 to 35°C for 2 to 3 hours to obtain calcium hydroxide slurry.

[0010] A method for preparing a high specific surface area calcium-based flue gas desulfurization absorbent includes the following steps: S1. Mix the calcium-based matrix, nano-silicon-based modifier and organic template agent according to the specified ratio, add deionized water and stir to disperse to form a precursor slurry; S2. The precursor slurry is dried and shaped to obtain pore-forming precursor particles; S3. The pore-forming precursor particles are subjected to low-temperature treatment under inert gas protection to remove residual moisture and some organic impurities and stabilize the particle structure. S4. Medium-temperature sintering: The pre-activated particles are sintered by further heating. S5. The sintered particles are placed in a vacuum environment to remove residual organic template agent. After cooling and crushing, the high specific surface area calcium-based flue gas desulfurization absorbent is obtained.

[0011] More preferably, the process parameters for wet mixing of the precursor in step S1 are: liquid-to-solid ratio of 3:1 to 5:1 (mL / g), stirring speed of 300 to 500 r / min, stirring temperature of 40 to 60℃, and stirring time of 60 to 90 min.

[0012] More preferably, in step S2, the template pore-forming process is carried out by spray drying, with the following specific parameters: inlet air temperature 180-220℃, outlet air temperature 80-100℃, feed rate 20-30 mL / min, and the particle size of the precursor particles obtained after drying is 100-200 μm.

[0013] More preferably, step S3, low-temperature pre-activation, is carried out under inert gas protection. The inert gas is nitrogen or argon, the flow rate is 0.5–1 L / min, the heating rate is 5–8 °C / min, the activation temperature is 250–300 °C, and the holding time is 2–3 h.

[0014] More preferably, the process parameters for the medium-temperature sintering in step S4 are: heating rate of 5–8 °C / min, sintering temperature of 600–700 °C, and holding time of 3–4 h; the parameters for the vacuum demolding in step S5 are: vacuum degree of -0.08–-0.1 MPa, demolding temperature of 400–450 °C, holding time of 1.5–2 h, and cooling rate controlled at 10–15 °C / min, ultimately pulverizing the target absorbent to a particle size of 50–100 μm. The beneficial effects of this invention are: This invention significantly improves upon the problems of traditional calcium-based absorbents, such as low specific surface area, simple pore structure, limited adsorption sites, and easy sintering and clogging, by constructing a composite system of calcium-based matrix, nano-silicon-based modifier, and organic template agent, combined with a multi-level pore structure directional control strategy. By rationally controlling the silicon-calcium molar ratio between 0.05 and 0.2, the nano-silicon component is uniformly distributed in the material, effectively inhibiting the sintering and agglomeration of CaO or Ca(OH)2 under high-temperature conditions, thereby enhancing the thermal stability and cycle life of the material. Simultaneously, utilizing organic template agents with controllable decomposition characteristics (such as polyethylene glycol, CTAB, etc.), a large number of well-connected mesopores and some macropores are formed during subsequent heat treatment, constructing an adsorption system with high specific surface area and hierarchical pore structure, improving the mass transfer efficiency and reaction contact probability of SO2 gas. The absorbent prepared by this invention has a specific surface area of ​​over 60 m² / g, a mesoporous volume fraction exceeding 70%, and a pore volume of 0.35–0.55 cm³ / g. It maintains a desulfurization efficiency of over 95% over a wide temperature window, and the absorbent utilization rate is no less than 80%. Furthermore, the integrated preparation process of this invention, which combines wet mixing, template pore formation, low-temperature pre-activation, medium-temperature sintering, and vacuum template removal, ensures structural integrity and performance while avoiding the damage to the pore structure caused by traditional high-temperature calcination. Overall energy consumption is reduced by more than 30%, significantly improving the feasibility and economy of industrial preparation. Detailed Implementation

[0015] The technical solutions of the present invention will be clearly and completely described below with reference to the embodiments of the present invention. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative effort are within the scope of protection of the present invention.

[0016] Example 1: Verification that even with low amounts of each component, the structural design and preparation process proposed in this invention can still effectively construct a hierarchical porous structure and ensure the performance of the absorbent.

[0017] The high specific surface area calcium-based flue gas desulfurization absorbent comprises the following raw materials in parts by weight: 75 parts calcium-based main body, 5 parts nano-silicon-based modifier, and 7 parts organic template agent. The preparation steps of the high specific surface area calcium-based flue gas desulfurization absorbent are as follows: S1. Weigh 75 g of industrial-grade calcium hydroxide micro powder as the calcium-based matrix; 5 g of nano-silica with a particle size of 20 nm, purity ≥99.5%, and specific surface area of ​​approximately 150 m² / g as the nano-silica-based modifier; and 7 g of polyethylene glycol-6000 with a molecular weight of 6000 as the organic template agent. Add the three components to 300 mL of deionized water (liquid-solid ratio of 3:1). Stir the mixture in a three-necked flask at 40 °C for 60 minutes at a stirring speed of 300 r / min using a mechanical stirrer to obtain a uniformly dispersed precursor slurry. S2. The above slurry is immediately fed into a spray dryer for drying. The equipment is configured as follows: dual-flow spray nozzle, atomization pressure 0.2 MPa, inlet air temperature 180℃, outlet air temperature 80℃, and feed rate 20 mL / min. After drying, precursor pore-forming particles with good flowability and a particle size of approximately 100 μm are obtained. S3. Place the spray-dried particles into a tube furnace and purge with high-purity nitrogen (≥99.999%) at a flow rate of 0.5 L / min to maintain an inert atmosphere. Control the heating rate to 5℃ / min and heat to 250℃. Then, keep the temperature constant for 2 hours to remove residual moisture and some organic components from the precursor particles and stabilize the material structure. S4. Continue heating the pre-activated particles to 600℃ in the same tube furnace, maintaining a heating rate of 5℃ / min, and sinter at a constant temperature for 3 hours. S5. The sintered particles are transferred to a vacuum furnace for template removal treatment. The vacuum degree is set to -0.08 MPa, the temperature is raised to 400℃, the holding time is 1.5 hours, and the cooling rate is controlled at 10℃ / min. Then, the treated absorbent is pulverized to a particle size of 50 μm using an airflow pulverizer to obtain the high specific surface area calcium-based flue gas desulfurization absorbent.

[0018] Example 2: Verification of the ultimate response capability of the process of the present invention to the construction and performance improvement of absorbent structure under the condition of high dosage of each component.

[0019] The high specific surface area calcium-based flue gas desulfurization absorbent comprises the following raw materials in parts by weight: 88 parts calcium-based main body, 12 parts nano-silicon-based modifier, and 13 parts organic template agent. The preparation steps of the high specific surface area calcium-based flue gas desulfurization absorbent are as follows: S1. Weigh 88 g of calcium oxide and hydrate it. Mix the calcium oxide with deionized water at a mass ratio of 1:3.5 and place it in a constant temperature water bath at 30°C for 2.5 hours to obtain calcium hydroxide slurry. Weigh 12 g of industrial grade sodium silicate raw material and add it to 80 g of deionized water. Treat it in an ultrasonic dispersion device at 350 W power for 35 minutes to obtain a uniform solution. Then dry it by spray drying. Set the inlet air temperature to 200°C and the outlet air temperature to 85°C to obtain nano-sodium silicate powder with a particle size of about 50 nm. Weigh 13 g of sodium dodecylbenzene sulfonate as an organic template agent. Mix the hydrated calcium hydroxide slurry, the dried nano-sodium silicate powder and the organic template agent together. Add deionized water to make the liquid-solid ratio 5:1. Control the stirring temperature at 60°C, the speed at 500 r / min and the mixing time at 90 minutes to form a precursor slurry. S2. The precursor slurry is fed into a dual-flow spray dryer, with the atomization pressure set to 0.25 MPa, the inlet air temperature to 220℃, the outlet air temperature to 100℃, and the feed rate to 30 mL / min. The dried material is a free-flowing granular material with an average particle size of about 200 μm. S3. The dried precursor particles were placed in a tube furnace and pre-activated at low temperature under a high-purity nitrogen atmosphere (flow rate 1.0 L / min). The heating rate was controlled at 8℃ / min. After heating to 300℃, the temperature was held for 3 hours to remove residual moisture and some organic template agent and stabilize the particle morphology. S4. Continue heating the pre-activated particles to 700℃ at a heating rate of 8℃ / min, and hold for 4 hours to complete the medium-temperature sintering process; S5. The sintered particles are placed in a vacuum tube furnace for template removal treatment. The vacuum degree is controlled at -0.1 MPa, the treatment temperature is set at 450℃, and the holding time is 2 hours. Then, the temperature is cooled to room temperature at a cooling rate of 15℃ / min. Finally, the particles are pulverized to an average particle size of 100 μm using an air jet mill to obtain a high specific surface area calcium-based flue gas desulfurization absorbent.

[0020] Example 3: Based on the intermediate ratio conditions of each component, the optimal coordination of the process parameters and the representativeness of the material properties of the present invention are verified.

[0021] The high specific surface area calcium-based flue gas desulfurization absorbent comprises the following raw materials in parts by weight: 81.5 parts calcium-based main body, 8.5 parts nano-silicon-based modifier, and 10 parts organic template agent; The preparation steps of the high specific surface area calcium-based flue gas desulfurization absorbent are as follows: S1. Weigh 81.5 g of industrial-grade calcium hydroxide as the calcium-based main body; weigh 8.5 g of nano-silica, with a particle size of about 35 nm, a purity of ≥99.5%, and a specific surface area of ​​about 175 m² / g, as the nano-silica-based modifier; weigh 10 g of polyethylene glycol-6000 (molecular weight 6000) as the organic template agent. Add the three to 320 mL of deionized water with a liquid-to-solid ratio of 4:1. Wet mix the mixture at 50°C using a mechanical stirring device at a stirring speed of 400 r / min for 75 minutes to ensure uniform dispersion of the slurry and the formation of a stable precursor system. S2. The precursor slurry obtained by stirring is dried and granulated by a spray drying device. The atomization pressure is set to 0.22 MPa, the inlet air temperature is 200℃, the outlet air temperature is 90℃, and the feed rate is 25 mL / min to obtain uniform pore-forming precursor particles with a particle size of about 150 μm. S3. Place the above particles in a tube furnace with atmosphere control, and under an argon protective atmosphere (flow rate of 0.75 L / min), control the heating rate to 6℃ / min, slowly heat to 275℃, hold for 2.5 hours, and perform low-temperature pre-activation treatment. S4. Continue heating the activated particles to 650℃ at a rate of 6℃ / min and sinter at a constant temperature for 3.5 hours to complete the skeleton shaping and further form a stable mesoporous structure and a certain proportion of macroporous structure. S5. The sintered sample was placed in a vacuum demolding device for processing. The vacuum degree was set to -0.09 MPa, the temperature was set to 425℃, the holding time was 1.8 hours, and the cooling process was controlled at 12.5℃ / min. Then, the particles were crushed into fine powder with a particle size of about 75 μm using an airflow pulverizer to obtain a calcium-based flue gas desulfurization absorbent with a high specific surface area.

[0022] Comparative Example 1: To verify the changes in absorbent performance without the introduction of nano-silicon-based modifiers, the absorbent was prepared by adding only a calcium-based host and an organic template agent.

[0023] The high specific surface area calcium-based flue gas desulfurization absorbent comprises the following raw materials in parts by weight: 81.5 parts calcium-based main body and 10 parts organic template agent; The preparation steps of the high specific surface area calcium-based flue gas desulfurization absorbent are as follows: S1. Weigh 81.5 g of industrial grade calcium hydroxide as the calcium-based main body, and weigh 10 g of polyethylene glycol-6000 (molecular weight 6000) as the organic template agent. Add the two raw materials to 326 mL of deionized water (liquid-solid ratio approximately 4:1). Stir at 400 r / min for 75 minutes at 50°C to form a uniform precursor slurry. S2. The prepared precursor slurry is dried by spray drying equipment with atomization pressure of 0.22 MPa, inlet air temperature of 200℃, outlet air temperature of 90℃, and feed rate of 25 mL / min. The dried precursor particles have a particle size of about 150 μm. S3. The dried precursor particles were placed in an inert atmosphere (argon, flow rate 0.75 L / min) for low-temperature pre-activation treatment. The heating rate was set to 6℃ / min. After heating to 275℃, the temperature was held for 2.5 hours to remove residual moisture and some organic components, and at the same time stabilize the particle structure. S4. After activation, the particles are heated to 650℃ at a rate of 6℃ / min and held for 3.5 hours to complete the skeleton shaping and structural development. S5. The sintered sample was placed in a vacuum apparatus for template removal. The vacuum level was set to -0.09 MPa, the treatment temperature was 425℃, the holding time was 1.8 hours, and the cooling rate was controlled at 12.5℃ / min. The sample was then pulverized to a particle size of approximately 75 μm using an airflow pulverizer to obtain a comparative high specific surface area calcium-based flue gas desulfurization absorbent.

[0024] Comparative Example 2: Verifying the feasibility of constructing an absorbent structure using only a calcium-based host and a nano-silicon-based modifier without the use of an organic template agent.

[0025] The high specific surface area calcium-based flue gas desulfurization absorbent comprises the following raw materials in parts by weight: 81.5 parts calcium-based main body and 8.5 parts nano-silicon-based modifier; The preparation steps of the high specific surface area calcium-based flue gas desulfurization absorbent are as follows: S1. Add 30 g of industrial-grade sodium silicate to deionized water to prepare a solution with a mass concentration of 12%. Place the solution in an ultrasonic device and ultrasonically disperse it at a power of 350 W for 35 min to ensure thorough and uniform dispersion and refinement of particles. Then, dry the treated solution using a spray dryer at a drying temperature of 200℃ to finally obtain nano-sodium silicate powder with an average particle size of approximately 35 nm. S2. Weigh 81.5 g of industrial-grade calcium hydroxide and 8.5 g of the nano-sodium silicate prepared above, for a total of 90 g of raw materials (without adding organic template agent). Add the raw materials to 360 mL of deionized water (liquid-solid ratio 4:1) and stir at 400 r / min for 75 min at 50℃ to form a uniform precursor slurry; S3. The above slurry is dried and pore-forming through a spray drying device. The atomization pressure is set to 0.22 MPa, the inlet air temperature is 200℃, the outlet air temperature is 90℃, and the feed rate is 25 mL / min. After drying, precursor particles with a particle size of about 150 μm are obtained. S4. Transfer the particles into a tube furnace, introduce argon gas for protection (flow rate 0.75 L / min), heat to 275℃ at a rate of 6℃ / min, hold for 2.5 hours to remove moisture and impurities and stabilize the structure; S5. The sample was further heated to 650℃ and held for 3.5 hours to complete the structural framework construction. The sample was then placed in a vacuum furnace with a vacuum of -0.09 MPa, a processing temperature of 425℃, and held for 1.8 hours. The cooling rate was controlled at 12.5℃ / min. The final sample was pulverized to 75 μm, which is the comparative high specific surface area calcium-based flue gas desulfurization absorbent.

[0026] Performance testing 1. Pore structure and specific surface area testing Nitrogen adsorption-desorption tests were performed on the absorbent samples using a specific surface area and pore size analyzer. Before testing, the samples were degassed under vacuum at 120℃ for 12 h to remove surface moisture and impurities. The specific surface area of ​​the samples was determined by the BET method, and the pore size distribution and pore volume were analyzed using the BJH method. Mesopores were defined as having a pore size of 2–50 nm, and the mesopore ratio was calculated. The test temperature was 77 K. The pore structure characteristics of the samples were analyzed, including total specific surface area, pore volume, and mesopore ratio. The results are shown in Table 1 below.

[0027] Table 1. Pore structure performance results of each absorbent sample

[0028] As shown in Table 1, the specific surface area of ​​the absorbents prepared in Examples 1-3 all reached or exceeded 60 m² / g, the mesoporous ratio was all higher than 70%, and the pore volume was significantly greater than that of Comparative Examples 1 and 2. This indicates that the present invention can effectively construct a hierarchical porous structure dominated by mesopores through the synergistic effect of nano-silicon-based modification and organic template agents. In contrast, the comparative sample, due to the lack of key structural control factors, had a significantly reduced specific surface area and mesoporous ratio, and its pore volume was limited, which was not conducive to gas mass transfer and reaction.

[0029] 2. Desulfurization performance test The flue gas desulfurization performance of each absorbent sample was tested using a fixed-bed reactor. 1.00 g of dried absorbent sample was placed in a quartz tube and reacted at a constant temperature of 150℃ for 240 min. The simulated flue gas composition was: SO2 concentration 1000 ppm, O2 concentration 5%, N2 as the balance gas, and a total gas flow rate of 500 mL / min. The outlet gas was collected, and the SO2 concentration was monitored in real time using an ultraviolet flue gas analyzer to calculate the removal rate. After the test, the residual absorbent was titrated to determine the actual utilization rate of effective calcium, and the SO2 adsorption capacity per unit mass of absorbent (mg / g) was measured. Each sample was tested three times, and the average value was taken. The results are shown in Table 2 below.

[0030] Table 2 Desulfurization performance results of each sample

[0031] As shown in Table 2, Examples 1-3 significantly outperformed Comparative Examples 1 and 2 in terms of desulfurization efficiency, absorbent utilization rate, and SO2 adsorption capacity. Specifically, the desulfurization efficiency of the examples all exceeded 95%, indicating that the constructed hierarchical porous structure and composite modification system effectively promoted the diffusion and reaction of SO2 on the absorbent surface. Furthermore, the absorbent utilization rate of the examples all exceeded 80%, indicating a high degree of effective calcium participation in the reaction and more efficient utilization of calcium resources. In contrast, the comparative examples, due to imperfect pore structures or the lack of key regulatory components, exhibited limited reactivity and adsorption capacity.

[0032] 3. Anti-clogging performance and mechanical strength test Each absorbent sample was reacted in a fixed-bed apparatus under simulated flue gas conditions for 240 min (SO2 concentration 1000 ppm, 150℃, total flow rate 500 mL / min), then removed and dried at 120℃ for 12 h. Subsequently, BET and BJH tests were performed again using a specific surface area analyzer to calculate the retention rates of specific surface area and pore volume before and after the reaction. Simultaneously, the mechanical breakage rate of the samples was determined using a particle strength tester. Particle size distribution was detected using a laser particle size analyzer, and the proportion of samples with particle sizes concentrated in the 50–100 μm range (i.e., particle size concentration) was statistically analyzed, reflecting its dispersion performance and gas-solid contact efficiency suitable for dry desulfurization equipment such as spray towers. The results are shown in Table 3 below.

[0033] Table 3. Test results of anti-clogging performance and mechanical strength

[0034] As shown in Table 3, the absorbents of Examples 1 to 3 still exhibited good pore structure retention rates after simulated flue gas reaction, all exceeding 90%, significantly higher than Comparative Examples 1 and 2. This indicates that the hierarchical pore structure of the absorbent of the present invention has strong stability and is not prone to pore collapse or failure due to ash accumulation or reaction product blockage. Meanwhile, the particle size distribution of the sample examples was all above 87%, and the breakage rate was less than 10%. These properties demonstrate that the composite structure constructed in this invention, while ensuring desulfurization performance, also possesses excellent physical strength and process adaptability, especially maintaining stable operation under continuous use and high-intensity conditions.

[0035] In the description of this specification, references to terms such as "an embodiment," "example," "specific example," etc., indicate that a specific feature, structure, material, or characteristic described in connection with that embodiment or example is included in at least one embodiment or example of the invention. In this specification, illustrative expressions of the above terms do not necessarily refer to the same embodiment or example. Furthermore, the specific features, structures, materials, or characteristics described may be combined in any suitable manner in one or more embodiments or examples.

[0036] The foregoing has shown and described the basic principles, main features, and advantages of the present invention. Those skilled in the art should understand that the present invention is not limited to the above embodiments. The embodiments and descriptions in the specification are merely illustrative of the principles of the invention. Various changes and modifications can be made to the invention without departing from its spirit and scope, and all such changes and modifications fall within the scope of the claimed invention.

Claims

1. A high specific surface area calcium-based flue gas desulfurization absorbent, characterized in that, It contains the following raw materials in parts by weight: 75-88 parts calcium-based matrix, 5-12 parts nano-silicon-based modifier, and 7-13 parts organic template agent; The calcium-based matrix is ​​selected from one or more of calcium oxide, calcium hydroxide, industrial-grade calcium hydroxide micro powder, and light calcium oxide. The nano-silicon-based modifier is selected from one or more of nano-silica, nano-sodium silicate, nano-lithium silicate, and nano-potassium silicate. The organic template agent is selected from one or more of polyethylene glycol-6000, polyethylene glycol-4000, hexadecyltrimethylammonium bromide, and sodium dodecylbenzenesulfonate.

2. The high specific surface area calcium-based flue gas desulfurization absorbent according to claim 1, characterized in that: The silicon-calcium molar ratio of the nano-silicon-based modifier to the calcium-based matrix is ​​0.05–0.

2. The high specific surface area calcium-based flue gas desulfurization absorbent has the following physical performance parameters: specific surface area not less than 60 m² / g; mesopore volume fraction not less than 70%, wherein the mesopore diameter is 2-50 nm; and pore volume is 0.35-0.55 cm³ / g. The high specific surface area calcium-based flue gas desulfurization absorbent has a desulfurization efficiency of not less than 95% and an absorbent utilization rate of not less than 80%.

3. The high specific surface area calcium-based flue gas desulfurization absorbent according to claim 1, characterized in that, The nano-silicon-based modifier has a particle size of 20–50 nm, a purity of not less than 99.5%, and a specific surface area of ​​150–200 m² / g. When the nano-silicon-based modifier is nano-sodium silicate, its synthesis method includes the following steps: (1) Add industrial grade sodium silicate to deionized water to prepare a solution with a mass concentration of 10-15%; (2) Disperse the ultrasonically in an ultrasonic device at a power of 300-400 W for 30-40 min; (3) Nano-sized sodium silicate particles were obtained by spray drying at 180-220°C.

4. The high specific surface area calcium-based flue gas desulfurization absorbent according to claim 1, characterized in that, The organic template agent is polyethylene glycol-6000, with a molecular weight of 5800-6200 and a solubility of ≥100g / L in water at 25℃.

5. The high specific surface area calcium-based flue gas desulfurization absorbent according to claim 1, characterized in that, When the calcium-based matrix is ​​calcium oxide, it needs to undergo hydration treatment; the hydration treatment method of calcium oxide includes: mixing calcium oxide and deionized water at a mass ratio of 1:3 to 1:4, stirring and reacting at 25 to 35°C for 2 to 3 hours to obtain calcium hydroxide slurry.

6. A method for preparing a high specific surface area calcium-based flue gas desulfurization absorbent as described in claim 1, characterized in that, Includes the following steps: S1. Mix the calcium-based matrix, nano-silicon-based modifier and organic template agent according to the specified ratio, add deionized water and stir to disperse to form a precursor slurry; S2. The precursor slurry is dried and shaped to obtain pore-forming precursor particles; S3. The pore-forming precursor particles are subjected to low-temperature treatment under inert gas protection to remove residual moisture and some organic impurities and stabilize the particle structure. S4. Medium-temperature sintering: The pre-activated particles are sintered by further heating. S5. The sintered particles are placed in a vacuum environment to remove residual organic template agent. After cooling and crushing, the high specific surface area calcium-based flue gas desulfurization absorbent is obtained.

7. The preparation method of the high specific surface area calcium-based flue gas desulfurization absorbent according to claim 6, characterized in that, The process parameters for wet mixing of the precursor in step S1 are: liquid-to-solid ratio of 3:1 to 5:1 (mL / g), stirring speed of 300 to 500 r / min, stirring temperature of 40 to 60℃, and stirring time of 60 to 90 min.

8. The preparation method of the high specific surface area calcium-based flue gas desulfurization absorbent according to claim 6, characterized in that, The template pore-forming process in step S2 is carried out by spray drying, with the following specific parameters: inlet air temperature 180-220℃, outlet air temperature 80-100℃, feed rate 20-30 mL / min, and the particle size of the precursor particles obtained after drying is 100-200 μm.

9. The preparation method of the high specific surface area calcium-based flue gas desulfurization absorbent according to claim 6, characterized in that, The low-temperature pre-activation step S3 is carried out under the protection of an inert gas, which is nitrogen or argon, with a flow rate of 0.5 to 1 L / min, a heating rate of 5 to 8 °C / min, an activation temperature of 250 to 300 °C, and a holding time of 2 to 3 h.

10. The preparation method of the high specific surface area calcium-based flue gas desulfurization absorbent according to claim 6, characterized in that, The process parameters for the medium-temperature sintering in step S4 are: heating rate of 5-8℃ / min, sintering temperature of 600-700℃, and holding time of 3-4 h; the parameters for the vacuum demolding in step S5 are: vacuum degree of -0.08--0.1 MPa, demolding temperature of 400-450℃, holding time of 1.5-2 h, cooling rate controlled at 10-15℃ / min, and finally pulverizing the target absorbent to a particle size of 50-100 μm.

Images