Starch pore-enlarging type high-chlorine-capacity long-acting high-temperature dechlorinating agent and preparation method thereof

Abstract

The invention relates to a starch pore-enlarging type high-chlorine-capacity long-acting high-temperature dechlorinating agent and a preparation method thereof, and belongs to the technical field of dechlorinating, the starch pore-enlarging type high-chlorine-capacity long-acting high-temperature dechlorinating agent comprises the following raw materials: complexing coating calcium hydroxide, modified hydroxyapatite, a composite inorganic adhesive, reinforcing and toughening whiskers, a composite pore-forming agent, a composite synergist, nano calcium carbonate and water; according to the starch reaming type high-chlorine-capacity long-acting high-temperature dechlorinating agent obtained by the invention, the breakthrough chlorine capacity is 40.9 to 44.9 percent, the crushing strength is 139 to 151N. Cm <-1 >, and the abrasion rate is 0.8 to 1.5 percent.

Description

Technical Field

[0001] This invention relates to a starch-based, pore-expanding, high-chlorine-capacity, long-lasting, high-temperature dechlorinating agent and its preparation method, belonging to the field of dechlorination technology. Background Technology

[0002] The generation of chlorine-containing gases mainly originates from the combustion of fossil fuels like coal and the rapidly increasing incineration of waste. If released into the atmosphere, chlorine-containing gases in the flue gas contribute to increased acid rain and cause significant harm to both nature and human health. Furthermore, they pose a considerable risk to equipment within combustion systems: the highly acidic chlorine in the flue gas causes high-temperature corrosion damage to furnace heating surfaces and low-temperature corrosion to tail-end heating surfaces, leading to increased steam parameters, corrosion of heat exchanger surfaces, and severely shortening equipment lifespan. In particular, HCl gas readily reacts with desulfurizing agents in desulfurization systems to form volatile chlorides, reducing desulfurization efficiency, clogging pipeline systems, and, at medium to high temperatures, promoting the formation of highly hazardous pollutants such as polychlorinated dibenzo-p-dioxins (PCBs) and polychlorinated dibenzo-p-furans (PCBs). Removing chlorine-containing gases at lower temperatures results in significant energy losses for power plants, directly reducing net power generation. Therefore, removing HCl under medium to high temperature conditions is one of the core tasks of flue gas treatment. The removal of HCl in gasification combined cycle (IGCC) power generation systems and gasification fuel cells (MCFC) places higher demands on these systems. In IGCC systems, the presence of HCl can corrode gas turbine blades, requiring the HCl content in the gas fuel to not exceed 0.5 ppm. In MCFC systems, HCl in the gas fuel readily forms low-boiling-point compounds with the electrolyte. These compounds easily evaporate at high temperatures, leading to electrolyte loss. Analysis shows that even a HCl content of just 1 ppm in the gas fuel can increase battery resistance, resulting in a decrease in battery voltage. Therefore, high-temperature dechlorination is also one of the core tasks of both IGCC and MCFC systems.

[0003] High-temperature removal of hydrogen chloride generally employs chemical absorption separation technology. Currently, the commonly used industrial method involves designing the dechlorination reactor at the gasifier outlet and using adsorbents for gas-phase dechlorination. High-temperature gas-phase dechlorination agents remove hydrogen chloride through adsorption, offering high efficiency and simple operation, thus enjoying wide application. Most dechlorination agents used domestically and internationally employ the method of impregnating porous carriers with active components. However, dechlorination agents obtained through this method generally have low chlorine capacity and operate at relatively low temperatures, often falling into the category of ambient or medium-temperature dechlorination agents. However, the outlet temperature of the gas produced by high-temperature gasifiers reaches 500-650℃. Using ambient or medium-temperature dechlorination agents necessitates the addition of a gas cooling system, increasing the overall production process and costs. Therefore, developing a high-temperature dechlorination agent capable of withstanding high temperatures for extended periods and possessing high chlorine penetration capacity is of significant practical importance in both reducing industrial dechlorination costs and protecting the environment.

[0004] Chinese patent CN114797758A discloses a high-temperature dechlorination agent and its preparation method. The high-temperature dechlorination agent is composed of hydrated alumina, magnesium hydroxide, magnesium oxide, binder, and other components. Although the highest chlorine penetration capacity of the high-temperature dechlorination agent obtained by this patent can reach 81.1% in the examples, the patent does not characterize the mechanical properties of the dechlorination agent, nor does it disclose whether it can be used for a long time under the harsh conditions of high-temperature dechlorination.

[0005] Chinese patent CN116159563A discloses a desulfurization and dechlorination agent, its preparation method, and its application. The desulfurization and dechlorination agent comprises two raw material components: a calcium-iron compound and a calcium-based compound. The calcium-iron compound is obtained by mixing red mud, glacial acetic acid, calcium hydroxide, and a pore-expanding agent, followed by molding and calcination. The calcium-based compound includes at least one of calcium carbonate and calcium hydroxide. While the desulfurization and dechlorination agent obtained by this patent can simultaneously desulfurize and dechlorinate, its chlorine capacity is very low, reaching a maximum of only 38.79%, and its crush resistance is not particularly high, with a maximum value of only 127 N / cm. Under high-temperature and high-gas-flow-rate conditions, its long-term service life may not be ideal.

[0006] As can be seen, high-temperature dechlorinating agents for removing hydrogen chloride gas still have problems such as low chlorine penetration capacity and insufficient mechanical properties. Therefore, developing a high-temperature dechlorinating agent with high chlorine penetration capacity, good mechanical properties, and long-term use at high temperature and high space velocity has very practical application value for reducing the industrial cost of dechlorination and protecting the environment. Summary of the Invention

[0007] To address the shortcomings of the existing technology, this invention provides a starch-based, high-chlorine-capacity, long-lasting high-temperature dechlorinating agent and its preparation method, achieving the following objectives: to prepare a high-temperature dechlorinating agent with high chlorine penetration capacity, good mechanical properties, and long-lasting performance under high temperature and high gas flow rate conditions.

[0008] To achieve the above-mentioned objectives, the present invention adopts the following technical solution: A starch-based pore-expanding, high-chlorine-capacity, long-lasting, high-temperature dechlorinating agent and its preparation method are disclosed. The starch-based pore-expanding, high-chlorine-capacity, long-lasting, high-temperature dechlorinating agent comprises the following raw materials: complexed and coated calcium hydroxide, modified hydroxyapatite, composite inorganic binder, reinforcing and toughening whiskers, composite pore-forming agent, composite synergist, nano-calcium carbonate, and water. The composite inorganic adhesive is composed of potassium silicate aqueous solution, silica sol, and pseudoboehmite. The reinforcing and toughening whiskers are potassium titanate whiskers; The composite pore-forming agent is composed of starch, calcium salt powder, and melamine cyanurate powder. The calcium salt powder is one of calcium oxalate and calcium citrate. The composite synergist is composed of zirconate powder and borate powder; The zirconate powder is one or a mixture of any two or more of potassium zirconate, calcium zirconate, lithium zirconate, magnesium aluminum zirconate, aluminum zirconate, strontium zirconate, and zinc zirconate in any mass ratio; The borate powder is one or a mixture of any two or more of zinc borate, calcium borate, calcium metaborate, magnesium borate, and aluminum borate in any mass ratio; The particle size of the nano-calcium carbonate is 10~100nm; The mass ratio of the complexed calcium hydroxide, modified hydroxyapatite, composite inorganic binder, reinforcing and toughening whiskers, composite pore-forming agent, composite synergist, nano calcium carbonate, and water is 250~450:60~160:25~60:4~12:13~45:6~30:120~300:330~660. The mass ratio of the potassium silicate aqueous solution, silica sol, and pseudoboehmite is 30~90:5~20:7~15; The potassium silicate aqueous solution contains 15-25 wt% potassium silicate and has a modulus of 1.5-3. The silica sol has a solid content of 20-30 wt%, a particle size of 10-100 nm, and a pH value of 8-10. The pseudoboehmite has an alumina content of 65-80 wt% and a colloidal rate of 95-99%. The potassium titanate whiskers have a diameter of 0.5~10μm and a length of 5~30μm; The mass ratio of starch, calcium salt powder, and melamine cyanurate powder is 30~100:10~40:4~15; The particle size of the calcium salt powder is 0.1~6μm; The particle size of the melamine cyanurate powder is 0.1~10μm; The mass ratio of zirconate powder to borate powder is 10~60:67~213; The zirconate powder has a particle size of 0.5~8μm; The borate powder has a particle size of 0.5~8μm; The preparation method of the starch-based pore-expanding high-chlorine-capacity long-acting high-temperature dechlorination agent includes four steps: preparing complex-coated calcium hydroxide, preparing modified hydroxyapatite, molding, and calcination. The following are further improvements to the above technical solution: Step 1: Preparation of complex-coated calcium hydroxide Add calcium hydroxide suspension to a reaction vessel, heat to a constant temperature, and then add 2,4,6-tris(aminohexanoic acid)-1,3,5-triazine with rapid stirring. Continue rapid stirring until the reaction is complete, then cool to room temperature, filter and dry to obtain complex-coated calcium hydroxide. In the calcium hydroxide suspension, the mass ratio of calcium hydroxide to water is 33~57:100; The mass ratio of the calcium hydroxide suspension to 2,4,6-tris(aminohexanoic acid)-1,3,5-triazine is 150~290:17~97; The heating is carried out to a constant temperature, which is 80~95℃; The rapid stirring is carried out at a speed of 1500~3000 rpm; The reaction is complete, and the reaction time is 2 to 3.5 hours.

[0009] Step 2: Preparation of modified hydroxyapatite Hydroxyapatite, methylsilicate and water were added to a dispersion vessel, dispersed at high speed until uniform, allowed to stand for reaction, then dispersed at high speed again, and then filtered and dried to obtain modified hydroxyapatite. The hydroxyapatite has a particle size of 0.3~9μm; The methylsilicate is one or a mixture of two of potassium methylsilicate and sodium methylsilicate in any mass ratio; The mass ratio of hydroxyapatite, methylsilicate, and water is 100~300:3~15:260~450; The high-speed dispersion is uniform, with a dispersion rate of 6000~9000 rpm and a dispersion time of 2~4 hours; The static reaction time is 2-5 hours; The process involves a second high-speed dispersion at a rate of 6000-9000 rpm for 1-2.5 hours. The drying process involves a drying temperature of 50-75℃ and a drying time of 12-20 hours.

[0010] Step 3, Shaping According to the raw material composition and mass ratio of starch-based pore-expanding high-chlorine capacity long-acting high-temperature dechlorinating agent, water, reinforcing and toughening whiskers, composite synergist, and nano calcium carbonate are first put into a double planetary mixer. After initial stirring and dispersion, complexed coated calcium hydroxide, composite inorganic binder, and composite pore-forming agent are added. After stirring and dispersing evenly, modified hydroxyapatite is added. After stirring and dispersing evenly again, a slurry is obtained. Then, the slurry is transferred into a twin-screw extruder and extruded to obtain long strip-shaped particles. After drying, the formed dechlorinating agent granules are obtained. The initial stirring and dispersion process involves a stirring rate of 120-260 rpm, a dispersion rate of 5000-8000 rpm, and a stirring and dispersion time of 2-4.5 hours. The mixture is then stirred and dispersed until uniform, with a stirring rate of 150-300 rpm, a dispersion rate of 6000-9500 rpm, and a stirring and dispersion time of 1-3 hours. The second stirring and dispersion is carried out at a stirring rate of 100-200 rpm, a dispersion rate of 3000-4500 rpm, and a stirring and dispersion time of 3-6 hours. The drying process involves a drying temperature of 60-80℃ and a drying time of 20-30 hours. The elongated particles have a length of 10-20 mm and a cross-sectional diameter of 3-8 mm.

[0011] Step 4, roasting After calcining the original dechlorinating agent granules at 350~520℃ for 3~6 hours, they are cooled to room temperature to obtain a starch-based, pore-expanding, high-chlorine-capacity, long-lasting, high-temperature dechlorinating agent.

[0012] Compared with the prior art, the present invention achieves the following beneficial effects: 1. This invention uses 2,4,6-tris(aminohexanoic acid)-1,3,5-triazine to complex and coat calcium hydroxide. The 2,4,6-tris(aminohexanoic acid)-1,3,5-triazine contains three carboxyl groups at its terminal end, which have a complexing and adsorption effect on calcium ions. It precipitates and coats the calcium hydroxide surface by forming a complex with calcium ions. The coating shell formed by 2,4,6-tris(aminohexanoic acid)-1,3,5-triazine has a low thermal decomposition temperature. During calcination, the 2,4,6- After thermal decomposition, tris(aminohexanoic acid)-1,3,5-triazine forms micropores around calcium hydroxide. These micropores increase the contact area between hydrogen chloride gas and calcium hydroxide, thereby increasing the reaction rate between calcium hydroxide and hydrogen chloride and improving the efficiency of hydrogen chloride removal. Macroscopically, this is manifested as an increase in the chlorine penetration capacity. Moreover, the micropores generated by the thermal decomposition of 2,4,6-tris(aminohexanoic acid)-1,3,5-triazine have almost no effect on the mechanical properties of the high-temperature dechlorination agent particles. 2. This invention significantly enhances the penetration capacity and mechanical strength of the dechlorinating agent by adding hydroxyapatite. This allows the high-temperature dechlorinating agent to maintain high penetration capacity and mechanical strength under high-temperature, high-space-velocity dechlorination conditions, thus ensuring its long-lasting and excellent dechlorination performance. Firstly, hydroxyapatite has numerous surface micropores, which increases the adsorption capacity of the high-temperature dechlorinating agent for hydrogen chloride, thereby prolonging the residence time of hydrogen chloride gas inside the dechlorinating agent and allowing the active substances inside the dechlorinating agent to react more fully with hydrogen chloride. Secondly, hydroxyapatite has certain dechlorination reactivity; the calcium ions it contains can react with hydrogen chloride to form calcium chloride. Furthermore, hydroxyapatite has a melting point of 1650℃, maintaining good mechanical properties in high-temperature dechlorination environments of 500-650℃. Finally, this invention uses methylsilicate to modify the surface of hydroxyapatite, which promotes the hydroxyl content of the dechlorinating agent. The uniform dispersion of apatite in the aqueous phase avoids agglomeration problems, thereby promoting and enhancing the adsorption and retention of hydrogen chloride by hydroxyapatite. Furthermore, during the modification of hydroxyapatite by methylsilicate, potassium or sodium ions are introduced into the hydroxyapatite (due to the adsorption effect of the micropores on the surface of hydroxyapatite and the ion exchange function of hydroxyapatite itself). Potassium or sodium ions will form potassium or sodium oxides during the calcination step. These two alkali metal oxides have a very high removal efficiency for hydrogen chloride, which may also improve the dechlorination effect of the dechlorinating agent particles to a certain extent. In addition, the hydrophobic film formed by methylsilicate on the surface of hydroxyapatite will sinter into silicon oxides during the calcination step. This process will promote the bonding force between hydroxyapatite and other components of the dechlorinating agent particles, and will also improve the crushing strength of the dechlorinating agent particles and reduce the wear rate of the dechlorinating agent particles to a certain extent. 3. The composite synergist composed of zirconate and borate added in this invention can not only significantly improve the dechlorination performance of the dechlorinating agent, but also improve its mechanical properties. Both zirconate and borate have certain reactivity with hydrogen chloride. The anionic parts of zirconate and borate, namely zirconate ions and borate ions, readily form corresponding weak acids with hydrogen chloride and decompose into corresponding zirconium oxides and boron oxides at high temperatures. The cationic parts of zirconate and borate form corresponding salts with hydrogen chloride. Therefore, zirconate and borate have a very significant synergistic effect on the absorption and removal of hydrogen chloride. In addition, zirconate and borate themselves have high melting points and mechanical strength. The addition of these two will greatly improve the mechanical strength of the dechlorinating agent particles. 4. This invention designs a composite pore-forming agent composed of starch, calcium salt powder, and melamine cyanurate powder. Starch has a low decomposition temperature and high decomposition rate. Its main function is to form larger micropores inside the dechlorinating agent particles through rapid low-temperature decomposition of starch. This ensures that the dechlorinating agent does not create excessive resistance to the gas under high-temperature, high-space-velocity dechlorination conditions. Excessive gas resistance will affect dechlorination efficiency and increase equipment manufacturing costs. Because excessive gas resistance requires maintaining a high space velocity, the gas pressure must be increased, and the pressure resistance of the equipment must be correspondingly improved. Salt powder and melamine cyanurate powder have high decomposition temperatures and their main function is to form ultra-micropores during the high-temperature calcination process. Melamine cyanurate powder has a very high decomposition temperature and a relatively slow decomposition rate, which plays a decisive role in the formation of extremely fine micropores. When these two substances are combined with starch, they can form a microporous structure with a gradient distribution of pore size. This multi-level microporous structure can reduce gas resistance and also take into account the adsorption and retention of hydrogen chloride gas inside the dechlorinating agent, ultimately achieving a high-penetration chlorine capacity dechlorination effect of the dechlorinating agent under high temperature and high space velocity. 5. The composite inorganic binder added in this invention, consisting of potassium silicate aqueous solution, silica sol, and pseudoboehmite, provides excellent adhesion during the low-temperature drying stage and forms relatively dense oxides during the high-temperature calcination step. This promotes denser sintering between the raw material powders of the dechlorinating agent, resulting in high-temperature dechlorinating agent particles with good mechanical strength. This lays a very good foundation and prerequisite for the long-term use of the high-temperature dechlorinating agent under high temperature and high air velocity conditions. 6. The reinforcing and toughening whiskers added in this invention, namely potassium titanate whiskers, together with nano-calcium carbonate, play a very important role in the formation of high-strength dechlorination agent particles. Moreover, nano-calcium carbonate, relying on its huge specific surface area and high reactivity with hydrogen chloride, plays a crucial role in the dechlorination reaction as the main reactant. 7. The starch-based, pore-expanding, high-chlorine-capacity, long-lasting high-temperature dechlorinating agent obtained in this invention has a chlorine penetration capacity of 40.9% to 44.9% and a crushing strength of 139 to 151 N·cm. -1 The wear rate is 0.8~1.5%. Attached Figure Description

[0013] Figure 1 The image shows a 2000x magnified cross-section of the starch-based high-chlorine-capacity, long-lasting, high-temperature dechlorinating agent with expanded pores obtained in Example 1. Figure 2 The image shows a scanning electron microscope (SEM) image of the cross-section of the starch-based, high-chlorine-capacity, long-lasting, high-temperature dechlorinating agent obtained in Example 2, magnified 2000 times. Detailed Implementation

[0014] The preferred embodiments of the present invention are described below. It should be understood that the preferred embodiments described herein are for illustration and explanation only and are not intended to limit the present invention.

[0015] Example 1: Preparation method of a starch-based, pore-expanding, high-chlorine-capacity, long-lasting, high-temperature dechlorinating agent Step 1: Preparation of complex-coated calcium hydroxide Add calcium hydroxide suspension to a reaction vessel, heat to a constant temperature, and then add 2,4,6-tris(aminohexanoic acid)-1,3,5-triazine with rapid stirring. Continue rapid stirring until the reaction is complete, then cool to room temperature, filter and dry to obtain complex-coated calcium hydroxide. In the calcium hydroxide suspension, the mass ratio of calcium hydroxide to water is 43:100; The mass ratio of the calcium hydroxide suspension to 2,4,6-tris(aminohexanoic acid)-1,3,5-triazine is 180:23; The heating is carried out to a constant temperature of 90°C. The rapid stirring is carried out at a stirring rate of 2000 rpm; The reaction was complete, and the reaction time was 3 hours.

[0016] Step 2: Preparation of modified hydroxyapatite Hydroxyapatite, methylsilicate and water were added to a dispersion vessel, dispersed at high speed until uniform, allowed to stand for reaction, then dispersed at high speed again, and then filtered and dried to obtain modified hydroxyapatite. The hydroxyapatite has a particle size of 1 μm; The methylsilicate is potassium methylsilicate; The mass ratio of hydroxyapatite, methylsilicate, and water is 260:11:360; The high-speed dispersion is uniform, with a dispersion rate of 8000 rpm and a dispersion time of 3 hours; The static reaction was allowed to proceed for 4 hours. The process involves high-speed dispersion again, with a dispersion rate of 8000 rpm and a dispersion time of 2 hours. The drying process was carried out at a temperature of 65°C for 17 hours.

[0017] Step 3, Shaping According to the raw material composition and mass ratio of starch-based pore-expanding high-chlorine capacity long-acting high-temperature dechlorinating agent, water, reinforcing and toughening whiskers, composite synergist, and nano calcium carbonate are first put into a double planetary mixer. After initial stirring and dispersion, complexed coated calcium hydroxide, composite inorganic binder, and composite pore-forming agent are added. After stirring and dispersing evenly, modified hydroxyapatite is added. After stirring and dispersing evenly again, a slurry is obtained. Then, the slurry is transferred into a twin-screw extruder and extruded to obtain long strip-shaped particles. After drying, the formed dechlorinating agent granules are obtained. The raw material composition of the starch-based pore-expanding high-chlorine-capacity long-acting high-temperature dechlorination agent includes complexed coated calcium hydroxide, modified hydroxyapatite, composite inorganic binder, reinforcing and toughening whiskers, composite pore-forming agent, composite synergist, nano calcium carbonate, and water. The mass ratio of the complexed calcium hydroxide, modified hydroxyapatite, composite inorganic binder, reinforcing and toughening whiskers, composite pore-forming agent, composite synergist, nano calcium carbonate, and water is 300:110:45:9:30:20:260:450. The composite inorganic adhesive is composed of potassium silicate aqueous solution, silica sol, and pseudoboehmite. The reinforcing and toughening whiskers are potassium titanate whiskers; The composite pore-forming agent is composed of starch, calcium salt powder, and melamine cyanurate powder. The calcium salt powder is calcium oxalate; The composite synergist is composed of zirconate powder and borate powder; The zirconate powder is potassium zirconate; The borate powder is zinc borate; The particle size of the nano-calcium carbonate is 30 nm; The mass ratio of the potassium silicate aqueous solution, silica sol, and pseudoboehmite is 60:13:12. The potassium silicate aqueous solution contains 18 wt% potassium silicate and has a modulus of 2. The silica sol has a solid content of 26 wt%, a particle size of 80 nm, and a pH value of 9. The pseudoboehmite has an alumina content of 75 wt% and a colloidal rate of 97%. The potassium titanate whiskers have a diameter of 3 μm and a length of 15 μm; The mass ratio of starch, calcium salt powder, and melamine cyanurate powder is 70:20:8; The calcium salt powder has a particle size of 2 μm; The particle size of the melamine cyanurate powder is 3 μm; The mass ratio of zirconate powder to borate powder is 53:99; The zirconate powder has a particle size of 2 μm; The borate powder has a particle size of 2 μm; The initial stirring and dispersion was carried out at a stirring rate of 220 rpm, a dispersion rate of 7000 rpm, and a stirring and dispersion time of 4 hours. The mixture was stirred and dispersed until uniform, with a stirring rate of 260 rpm, a dispersion rate of 7500 rpm, and a stirring and dispersion time of 2 hours. The mixture was stirred and dispersed again at a stirring rate of 140 rpm and a dispersion rate of 3500 rpm for 4 hours. The drying process was carried out at a temperature of 68°C for 26 hours. The elongated granules are 13 mm long and have a cross-sectional diameter of 5 mm.

[0018] Step 4, roasting After calcining the original dechlorinating agent granules at 420℃ for 4 hours, they were cooled to room temperature to obtain a starch-based, pore-expanding, high-chlorine-capacity, long-lasting, high-temperature dechlorinating agent.

[0019] Example 2: Preparation method of a starch-based pore-expanding, high-chlorine-capacity, long-lasting, high-temperature dechlorinating agent Step 1: Preparation of complex-coated calcium hydroxide Add calcium hydroxide suspension to a reaction vessel, heat to a constant temperature, and then add 2,4,6-tris(aminohexanoic acid)-1,3,5-triazine with rapid stirring. Continue rapid stirring until the reaction is complete, then cool to room temperature, filter and dry to obtain complex-coated calcium hydroxide. In the calcium hydroxide suspension, the mass ratio of calcium hydroxide to water is 33:100; The mass ratio of the calcium hydroxide suspension to 2,4,6-tris(aminohexanoic acid)-1,3,5-triazine is 150:17. The heating is carried out to a constant temperature of 80°C. The rapid stirring is carried out at a stirring rate of 1500 rpm; The reaction was complete, and the reaction time was 2 hours.

[0020] Step 2: Preparation of modified hydroxyapatite Hydroxyapatite, methylsilicate and water were added to a dispersion vessel, dispersed at high speed until uniform, allowed to stand for reaction, then dispersed at high speed again, and then filtered and dried to obtain modified hydroxyapatite. The hydroxyapatite has a particle size of 0.3 μm; The methylsilicate is sodium methylsilicate; The mass ratio of hydroxyapatite, methylsilicate, and water is 100:3:260. The high-speed dispersion is uniform, with a dispersion rate of 6000 rpm and a dispersion time of 2 hours; The static reaction was allowed to proceed for 2 hours. The process involves high-speed dispersion again, with a dispersion rate of 6000 rpm and a dispersion time of 1 hour. The drying process is carried out at a temperature of 50°C for 12 hours.

[0021] Step 3, Shaping According to the raw material composition and mass ratio of starch-based pore-expanding high-chlorine capacity long-acting high-temperature dechlorinating agent, water, reinforcing and toughening whiskers, composite synergist, and nano calcium carbonate are first put into a double planetary mixer. After initial stirring and dispersion, complexed coated calcium hydroxide, composite inorganic binder, and composite pore-forming agent are added. After stirring and dispersing evenly, modified hydroxyapatite is added. After stirring and dispersing evenly again, a slurry is obtained. Then, the slurry is transferred into a twin-screw extruder and extruded to obtain long strip-shaped particles. After drying, the formed dechlorinating agent granules are obtained. The raw material composition of the starch-based pore-expanding high-chlorine-capacity long-acting high-temperature dechlorination agent includes complexed coated calcium hydroxide, modified hydroxyapatite, composite inorganic binder, reinforcing and toughening whiskers, composite pore-forming agent, composite synergist, nano calcium carbonate, and water. The mass ratio of the complexed calcium hydroxide, modified hydroxyapatite, composite inorganic binder, reinforcing and toughening whiskers, composite pore-forming agent, composite synergist, nano calcium carbonate, and water is 250:60:25:4:13:6:120:330. The composite inorganic adhesive is composed of potassium silicate aqueous solution, silica sol, and pseudoboehmite. The reinforcing and toughening whiskers are potassium titanate whiskers; The composite pore-forming agent is composed of starch, calcium salt powder, and melamine cyanurate powder. The calcium salt powder is calcium citrate; The composite synergist is composed of zirconate powder and borate powder; The zirconate powder is calcium zirconate; The borate powder is calcium borate; The particle size of the nano-calcium carbonate is 10 nm; The mass ratio of the potassium silicate aqueous solution, silica sol, and pseudoboehmite is 30:5:7. The potassium silicate aqueous solution contains 15 wt% potassium silicate and has a modulus of 1.5. The silica sol has a solid content of 20 wt%, a particle size of 10 nm, and a pH value of 8. The pseudoboehmite has an alumina content of 65 wt% and a colloidal rate of 95%. The potassium titanate whiskers have a diameter of 0.5 μm and a length of 5 μm. The mass ratio of starch, calcium salt powder, and melamine cyanurate powder is 30:10:4. The calcium salt powder has a particle size of 0.1 μm; The particle size of the melamine cyanurate powder is 0.1 μm; The mass ratio of zirconate powder to borate powder is 10:67; The zirconate powder has a particle size of 0.5 μm; The borate powder has a particle size of 0.5 μm; The initial stirring and dispersion was carried out at a stirring rate of 120 rpm, a dispersion rate of 5000 rpm, and a stirring and dispersion time of 2 hours. The mixture was stirred and dispersed until uniform, with a stirring speed of 150 rpm, a dispersion speed of 6000 rpm, and a stirring and dispersion time of 1 hour. The mixture is stirred and dispersed again at a stirring speed of 100 rpm and a dispersion speed of 3000 rpm for 3 hours. The drying process is carried out at a temperature of 60°C for 20 hours. The elongated granules are 10 mm long and have a cross-sectional diameter of 3 mm.

[0022] Step 4, roasting After calcining the original dechlorinating agent granules at 350℃ for 6 hours, they were cooled to room temperature to obtain a starch-based, pore-expanding, high-chlorine-capacity, long-lasting, high-temperature dechlorinating agent.

[0023] Example 3: Preparation method of a starch-based pore-expanding, high-chlorine-capacity, long-lasting, high-temperature dechlorinating agent Step 1: Preparation of complex-coated calcium hydroxide Add calcium hydroxide suspension to a reaction vessel, heat to a constant temperature, and then add 2,4,6-tris(aminohexanoic acid)-1,3,5-triazine with rapid stirring. Continue rapid stirring until the reaction is complete, then cool to room temperature, filter and dry to obtain complex-coated calcium hydroxide. In the calcium hydroxide suspension, the mass ratio of calcium hydroxide to water is 57:100; The mass ratio of the calcium hydroxide suspension to 2,4,6-tris(aminohexanoic acid)-1,3,5-triazine is 290:97. The heating is carried out to a constant temperature of 95°C. The rapid stirring is carried out at a stirring rate of 3000 rpm. The reaction was complete, and the reaction time was 3.5 hours.

[0024] Step 2: Preparation of modified hydroxyapatite Hydroxyapatite, methylsilicate and water were added to a dispersion vessel, dispersed at high speed until uniform, allowed to stand for reaction, then dispersed at high speed again, and then filtered and dried to obtain modified hydroxyapatite. The hydroxyapatite has a particle size of 9 μm; The methylsilicate is potassium methylsilicate; The mass ratio of hydroxyapatite, methylsilicate, and water is 300:15:450; The high-speed dispersion is uniform, with a dispersion rate of 9000 rpm and a dispersion time of 4 hours; The static reaction was allowed to proceed for 5 hours. The process involves a second high-speed dispersion at a rate of 9000 rpm for 2.5 hours. The drying process involves a drying temperature of 75°C and a drying time of 20 hours.

[0025] Step 3, Shaping According to the raw material composition and mass ratio of starch-based pore-expanding high-chlorine capacity long-acting high-temperature dechlorinating agent, water, reinforcing and toughening whiskers, composite synergist, and nano calcium carbonate are first put into a double planetary mixer. After initial stirring and dispersion, complexed coated calcium hydroxide, composite inorganic binder, and composite pore-forming agent are added. After stirring and dispersing evenly, modified hydroxyapatite is added. After stirring and dispersing evenly again, a slurry is obtained. Then, the slurry is transferred into a twin-screw extruder and extruded to obtain long strip-shaped particles. After drying, the formed dechlorinating agent granules are obtained. The raw material composition of the starch-based pore-expanding high-chlorine-capacity long-acting high-temperature dechlorination agent includes complexed coated calcium hydroxide, modified hydroxyapatite, composite inorganic binder, reinforcing and toughening whiskers, composite pore-forming agent, composite synergist, nano calcium carbonate, and water. The mass ratio of the complexed calcium hydroxide, modified hydroxyapatite, composite inorganic binder, reinforcing and toughening whiskers, composite pore-forming agent, composite synergist, nano calcium carbonate, and water is 450:160:60:12:45:30:300:660. The composite inorganic adhesive is composed of potassium silicate aqueous solution, silica sol, and pseudoboehmite. The reinforcing and toughening whiskers are potassium titanate whiskers; The composite pore-forming agent is composed of starch, calcium salt powder, and melamine cyanurate powder. The calcium salt powder is calcium oxalate; The composite synergist is composed of zirconate powder and borate powder; The zirconate powder is lithium zirconate; The borate powder is calcium metaborate; The particle size of the nano-calcium carbonate is 100 nm; The mass ratio of the potassium silicate aqueous solution, silica sol, and pseudoboehmite is 90:20:15. The potassium silicate aqueous solution contains 25 wt% potassium silicate and has a modulus of 3. The silica sol has a solid content of 30 wt%, a particle size of 100 nm, and a pH value of 10. The pseudoboehmite has an alumina content of 80 wt% and a colloidal rate of 99%. The potassium titanate whiskers have a diameter of 10 μm and a length of 30 μm; The mass ratio of starch, calcium salt powder, and melamine cyanurate powder is 100:40:15. The calcium salt powder has a particle size of 6 μm; The particle size of the melamine cyanurate powder is 10 μm; The mass ratio of zirconate powder to borate powder is 60:213; The zirconate powder has a particle size of 8 μm; The borate powder has a particle size of 8 μm; The initial stirring and dispersion was carried out at a stirring rate of 260 rpm, a dispersion rate of 8000 rpm, and a stirring and dispersion time of 4.5 hours. The mixture was stirred and dispersed until uniform, with a stirring speed of 300 rpm, a dispersion speed of 9500 rpm, and a stirring and dispersion time of 3 hours. The mixture was stirred and dispersed again at a stirring speed of 200 rpm and a dispersion speed of 4500 rpm for 6 hours. The drying process is carried out at a temperature of 80°C for 30 hours. The elongated granules are 20 mm long and have a cross-sectional diameter of 8 mm.

[0026] Step 4, roasting After calcining the original dechlorinating agent granules at 520℃ for 3 hours, they were cooled to room temperature to obtain a starch-based, pore-expanding, high-chlorine-capacity, long-lasting, high-temperature dechlorinating agent.

[0027] Example 4: Preparation method of a starch-based pore-expanding, high-chlorine-capacity, long-lasting, high-temperature dechlorinating agent Steps 1 and 2 are the same as in Example 1; Step 3, Shaping The zirconate powder is magnesium aluminum zirconate; The borate powder is magnesium borate; Other operations are the same as in Example 1.

[0028] Step 4 is the same as in Example 1.

[0029] Example 5: Preparation method of a starch-based pore-expanding, high-chlorine-capacity, long-lasting, high-temperature dechlorinating agent Steps 1 and 2 are the same as in Example 1; Step 3, Shaping The zirconate powder is aluminum zirconate; The borate powder is aluminum borate; Other operations are the same as in Example 1.

[0030] Step 4 is the same as in Example 1.

[0031] Example 6: Preparation method of a starch-based pore-expanding, high-chlorine-capacity, long-lasting, high-temperature dechlorinating agent Steps 1 and 2 are the same as in Example 1; Step 3, Shaping The zirconate powder is strontium zirconate; Other operations are the same as in Example 1.

[0032] Step 4 is the same as in Example 1.

[0033] Example 7: Preparation method of a starch-based pore-expanding, high-chlorine-capacity, long-lasting, high-temperature dechlorinating agent Steps 1 and 2 are the same as in Example 1; Step 3, Shaping The zirconate powder is zinc zirconate; Other operations are the same as in Example 1.

[0034] Step 4 is the same as in Example 1.

[0035] Comparative Example 1: Based on Example 1, step 2 (preparation of modified hydroxyapatite) was omitted. In step 3 (molding), 110 parts of modified hydroxyapatite were replaced with 110 parts of nano-calcium carbonate in equal amounts. The specific operation is as follows: Step 1 is the same as in Example 1; Step 2 is omitted in the preparation of modified hydroxyapatite; Step 3, Shaping Replace 110 parts of modified hydroxyapatite with 110 parts of nano-calcium carbonate, and perform the other operations as in Example 1; Step 4 is the same as in Example 1.

[0036] Comparative Example 2: Based on Example 1, step 2 (preparation of modified hydroxyapatite) was omitted. In step 3 (molding), 110 parts of modified hydroxyapatite were replaced with an equal amount of 110 parts of hydroxyapatite. The specific operation is as follows: Step 1 is the same as in Example 1; Step 2 is omitted in the preparation of modified hydroxyapatite; Step 3, Shaping Replace 110 parts of modified hydroxyapatite with an equal amount of hydroxyapatite, and perform the other operations as in Example 1; The hydroxyapatite has a particle size of 1 μm; Step 4 is the same as in Example 1.

[0037] Comparative Example 3: Based on Example 1, in step 3, during molding, calcium salt powder and melamine cyanurate powder were not added to the composite pore-forming agent; only starch was added. 20 parts of calcium salt powder and 8 parts of melamine cyanurate powder were replaced with 28 parts of starch in equal amounts. The specific operation is as follows: Steps 1 and 2 are the same as in Example 1; Step 3, Shaping Replace 20 parts of calcium salt powder and 8 parts of melamine cyanurate powder with 28 parts of starch, and perform the same operations as in Example 1. Step 4 is the same as in Example 1.

[0038] Comparative Example 4: Based on Example 1, in step 3, during molding, the composite synergist was not added; instead, 20 parts of the composite synergist were replaced with 20 parts of water. The specific operation is as follows: Steps 1 and 2 are the same as in Example 1; Step 3, Shaping Replace 20 parts of compound synergist with 20 parts of water, and perform the other operations as in Example 1; Step 4 is the same as in Example 1.

[0039] Comparative Example 5: Based on Example 1, in step 3, during molding, only zirconate powder was added to the composite synergist, and 99 parts of borate powder were replaced with an equal amount of zirconate powder. The specific operation is as follows: Steps 1 and 2 are the same as in Example 1; Step 3, Shaping Replace 99 parts of borate powder with 99 parts of zirconate powder, and perform the other operations as in Example 1; Step 4 is the same as in Example 1.

[0040] Comparative Example 6: Based on Example 1, in step 3, during molding, only borate powder was added to the composite synergist, and 53 parts of zirconate powder were replaced with an equal amount of borate powder. The specific operation is as follows: Steps 1 and 2 are the same as in Example 1; Step 3, Shaping Replace 53 parts of zirconate powder with 53 parts of borate powder in equal amounts, and perform the other operations as in Example 1; Step 4 is the same as in Example 1.

[0041] Comparative Example 7: Based on Example 1, step 1 (preparation of complex-coated calcium hydroxide) was omitted, and in step 3 (molding), 300 parts of complex-coated calcium hydroxide were replaced with an equal amount of calcium hydroxide. The specific operation is as follows: Step 1, preparing complex-coated calcium hydroxide, is not performed; Step 2 is the same as in Example 1; Step 3, Shaping Replace 300 parts of complex-coated calcium hydroxide with an equal amount of calcium hydroxide, and perform the other operations as in Example 1; Step 4 is the same as in Example 1.

[0042] Performance testing: The following indicators were tested on the starch-based pore-expanding, high-chlorine-capacity, long-lasting high-temperature dechlorinating agents obtained in Examples 1, 2, 3, 4, 5, 6, and 7, and Comparative Examples 1, 2, 3, 4, 5, 6, and 7: 1. Chlorine penetration capacity test method: A fixed-bed evaluation was used. The diameter of the quartz glass reactor was 10 mm. 6 mL of high-temperature dechlorination agent was uniformly packed in the middle of the reactor, and 3 mL of 10-20 mesh quartz sand was packed above and below the high-temperature dechlorination agent. The inlet gas was simulated high-temperature coal gas with hydrogen chloride (simulated high-temperature coal gas was introduced with hydrogen chloride after passing through a chlorine mixing bottle), and the hydrogen chloride content in the inlet gas was 2300-4000 mg / m³. 3 The gas space velocity is 7000 h⁻¹. -1 At atmospheric pressure and an evaluation temperature of 650℃, the hydrogen chloride content in the outlet gas exceeds 1 mg / m³. 3 The time is called penetration. According to the formula: Penetration chlorine capacity = (mass content of chlorine in the dechlorinating agent after penetration) / (total mass of dechlorinating agent after penetration) × 100%, the penetration chlorine capacity of the high-temperature dechlorinating agent can be obtained. 2. Crushing strength: The crushing strength shall be tested in accordance with the "HG / T 2782-2024 Determination of Crushing Resistance of Chemical Catalyst Particles"; 3. Wear rate: The wear rate is tested in accordance with "HG / T 2976-2011 Determination of Wear Rate of Fertilizer Catalysts"; The specific test results are shown in Table 1: Table 1 As can be seen from the data in Table 1, the breakthrough chlorine capacity of Examples 1-7 is all above 40.9%, and the crushing strength is all above 139 N·cm. -1The wear rate does not exceed 1.5%, indicating that the starch-based pore-expanding high-chlorine-capacity long-lasting high-temperature dechlorinating agent obtained in this invention has a very high chlorine penetration capacity under high-temperature and high-space-velocity dechlorination conditions, and also has particularly good mechanical strength, namely, excellent crushing strength and wear rate. This shows that the starch-based pore-expanding high-chlorine-capacity long-lasting high-temperature dechlorinating agent prepared in this invention can achieve a long-lasting and long-life high-chlorine-capacity dechlorination effect under harsh high-temperature and high-space-velocity dechlorination conditions with excellent mechanical properties. In Comparative Example 1, no modified hydroxyapatite was added, and all modified hydroxyapatite was replaced with nano-calcium carbonate. The chlorine penetration capacity of Comparative Example 1 dropped sharply to 23.0%, which may be due to the fact that nano-calcium carbonate... The particles are extremely fine, with high surface activity and a high tendency to agglomerate. Excessive addition can lead to agglomeration of nano-calcium carbonate and over-densification of the dechlorinating agent particles during calcination, resulting in a significant reduction in the internal porosity of the dechlorinating agent. Under high-space velocity and high-temperature dechlorination conditions, the agglomeration of nano-calcium carbonate slows the reaction rate between calcium carbonate particles and hydrogen chloride. Furthermore, the over-densification of the dechlorinating agent particles affects the adsorption and retention of hydrogen chloride gas under high-space velocity operation conditions due to insufficient internal micropores. Ultimately, this hinders the sufficient reaction between the dechlorination active substances within the dechlorinating agent particles and hydrogen chloride, significantly reducing the dechlorination performance of the dechlorinating agent. The crushing strength of Comparative Example 1 increased to 158 N·cm. -1 The wear rate was reduced to 0.5%, which indirectly indicates that Comparative Example 1 had a higher density and therefore better mechanical properties. Furthermore, hydroxyapatite itself has a very good surface adsorption effect, resulting in good retention of hydrogen chloride. It also exhibits high reactivity with hydrogen chloride at high temperatures. Replacing all the hydroxyapatite with nano-calcium carbonate severely affected the adsorption and retention of hydrogen chloride by the dechlorinating agent particles, ultimately leading to a significant decrease in the chlorine penetration capacity. In Comparative Example 2, the hydroxyapatite added was not surface-modified with methylsilicate, resulting in a decrease in the chlorine penetration capacity to 34.8%, and a slight decrease in crushing strength to 136 N·cm. -1The wear rate increased to 1.9%, which may be because hydroxyapatite has a high surface polarity. Without surface modification, it is difficult to achieve good dispersion in the aqueous phase during the formation of the dechlorinating agent, thus hindering the adsorption and retention effect of hydroxyapatite on hydrogen chloride. Furthermore, the agglomeration caused by poor dispersion significantly reduces the specific surface area of ​​hydroxyapatite, thereby affecting the reaction efficiency between hydroxyapatite and hydrogen chloride. However, the formation of a hydrophobic film on the surface of hydroxyapatite by methylsilicate reduces the surface polarity of hydroxyapatite, thereby promoting the adsorption and retention effect of hydroxyapatite on water. The dispersion uniformity in the phase is important. Furthermore, during the modification of hydroxyapatite with methylsilicate, potassium or sodium ions are introduced into the hydroxyapatite (due to the adsorption effect of the micropores on the surface of hydroxyapatite and the ion exchange capacity of hydroxyapatite itself). During the calcination step, potassium or sodium ions form potassium or sodium oxides. These two alkali metal oxides have a very high removal efficiency for hydrogen chloride, which may also improve the dechlorination effect of the dechlorinating agent particles to some extent. The slight decrease in crushing strength and the increase in abrasion rate in Comparative Example 2 may be due to the unmodified hydroxyapatite. The uneven dispersion is the cause. Additionally, the hydrophobic film formed by methyl silicate on the surface of hydroxyapatite sintersects into silicon oxide during the calcination process. This process promotes the bonding force between hydroxyapatite and other components of the dechlorinating agent particles, and to some extent, also increases the crushing strength of the dechlorinating agent and reduces the wear rate. In Comparative Example 3, no calcium salt powder or melamine cyanurate powder was added to the composite pore-forming agent; only starch was added. The chlorine penetration capacity of Comparative Example 3 decreased significantly to 20.2%, the crushing strength also decreased drastically, and the wear rate increased significantly. This indicates that using only... Starch is used as a pore-forming agent. Due to its low decomposition temperature and high decomposition rate, starch forms too many large-diameter micropores inside the dechlorinating agent particles, causing a severe decline in the mechanical properties of the dechlorinating agent particles. At the same time, the large pore size inside the dechlorinating agent means that under high-temperature and high-space-velocity dechlorination conditions, the high-temperature gas experiences less resistance and has a very short residence time inside the dechlorinating agent particles. The active substances inside the dechlorinating agent do not have enough time to undergo a sufficient chemical adsorption effect with hydrogen chloride, ultimately leading to a severe decline in dechlorination performance. In Comparative Example 4, without the addition of a composite synergist, the breakthrough chlorine capacity decreased to 29.The crushing strength decreased significantly by 1%, while the wear rate increased significantly. This indicates that the composite synergist not only significantly improves the dechlorination performance of the dechlorinating agent but also enhances its mechanical properties. This may be because both zirconate and borate have certain reactivity with hydrogen chloride. The anionic portions of zirconate and borate, namely zirconate ions and borate ions, readily form corresponding weak acids with hydrogen chloride and decompose into corresponding zirconium oxides and boron oxides at high temperatures. Conversely, the cationic portions of zirconate and borate form corresponding salts with hydrogen chloride. Therefore, zirconate and borate have a very significant synergistic effect on the absorption and removal of hydrogen chloride. In addition, zirconate and borate themselves have high... The addition of both melting point and mechanical strength improves the mechanical strength of the dechlorinating agent particles to some extent. Therefore, in Comparative Example 4, which does not contain zirconate or borate, the crushing strength is significantly reduced, and the wear rate is correspondingly increased. Comparative Examples 5 and 6, which do not contain borate or zirconate respectively (i.e., Comparative Example 5 contains only zirconate and Comparative Example 6 contains only borate), both show a significant reduction in chlorine penetration capacity, but the reduction is less than that in Comparative Example 4. The chlorine penetration capacity of Comparative Example 5 is slightly higher than that of Comparative Example 6. This indicates that borate and zirconate have a good synergistic effect in enhancing the dechlorination effect, and the synergistic effect of zirconate on the dechlorination effect may be slightly greater than that of borate. Comparative Example 6, which only added borate, had a lower chloride penetration capacity than Comparative Example 5. This may be because the zirconate ion is less acidic and the resulting zirconium oxide is more stable, leading to greater reactivity of zirconate with hydrogen chloride than borate. Additionally, Comparative Example 6 had lower crushing strength and abrasion rate than Comparative Example 5. This may be because Comparative Example 6 did not contain zirconate, making it difficult to generate zirconium dioxide with better mechanical strength, resulting in inferior mechanical properties compared to Comparative Example 5. In Comparative Example 7, which did not perform complexation coating on calcium hydroxide, the chloride penetration capacity significantly decreased to 30.2%, while the crushing strength and abrasion rate remained largely unchanged. This may be due to the difference in reactivity between the hydrogen and oxygen groups. When calcium hydroxide is coated with a complex of 2,4,6-tris(aminohexanoic acid)-1,3,5-triazine, during calcination, the thermal decomposition of 2,4,6-tris(aminohexanoic acid)-1,3,5-triazine forms micropores around the calcium hydroxide. These micropores increase the contact area between hydrogen chloride gas and calcium hydroxide, thus increasing the reaction rate between calcium hydroxide and hydrogen chloride, and consequently improving the efficiency of hydrogen chloride removal. Macroscopically, this is manifested as an increase in the chlorine penetration capacity. Furthermore, judging from the crushing strength and abrasion rate of Comparative Example 7, the micropores generated by the thermal decomposition of 2,4,6-tris(aminohexanoic acid)-1,3,5-triazine have almost no effect on the mechanical properties of the high-temperature dechlorinating agent particles.

[0043] Appendix Figure 1 Appendix Figure 2The images shown are scanning electron microscope (SEM) images of the cross-sections of the starch-based pore-expanding high-chlorine-capacity long-lasting high-temperature dechlorinating agents obtained in Examples 1 and 2, magnified 2000 times. Both images show that the cross-section of the starch-based pore-expanding high-chlorine-capacity long-lasting high-temperature dechlorinating agent has many micropores of varying sizes. Large pores with diameters of tens of micrometers are rare, and most micropores have diameters ranging from submicrometers to several micrometers. The sintered material between the micropores is very dense, which may be due to the formation of a dense sintered material by the inorganic composite binder and nano-calcium carbonate during the high-temperature sintering process. This is consistent with the high crushing strength and low wear rate of the high-temperature dechlorinating agent particles measured in this invention.

[0044] The above description is only a preferred embodiment of the present invention, but the scope of protection of the present invention is not limited thereto. Any equivalent substitutions or modifications made by those skilled in the art within the scope of the technology disclosed in the present invention, based on the technical solution and inventive concept of the present invention, should be covered within the scope of protection of the present invention.

Claims

1. A starch-based, pore-expanding, high-chlorine-capacity, long-lasting, high-temperature dechlorinating agent, characterized in that: The starch-based pore-expanding high-chlorine-capacity long-lasting high-temperature dechlorination agent comprises the following raw materials: complexed and coated calcium hydroxide, modified hydroxyapatite, composite inorganic binder, reinforcing and toughening whiskers, composite pore-forming agent, composite synergist, nano-calcium carbonate, and water. The preparation method of the complex-coated calcium hydroxide is as follows: calcium hydroxide suspension is added to a reaction vessel, heated to a constant temperature, and then 2,4,6-tris(aminohexanoic acid)-1,3,5-triazine is added under rapid stirring. The stirring is continued to be rapid. After the reaction is complete, the mixture is cooled to room temperature, filtered, and dried to obtain complex-coated calcium hydroxide. The modified hydroxyapatite is prepared by adding hydroxyapatite, methylsilicate and water into a dispersion vessel, dispersing them at high speed until uniform, allowing them to stand and react, then dispersing them at high speed again, and finally filtering and drying them to obtain the modified hydroxyapatite. The hydroxyapatite has a particle size of 0.3~9μm; The methylsilicate is one or a mixture of two of potassium methylsilicate and sodium methylsilicate in any mass ratio; The composite inorganic adhesive is composed of potassium silicate aqueous solution, silica sol, and pseudoboehmite. The reinforcing and toughening whiskers are potassium titanate whiskers; The composite pore-forming agent is composed of starch, calcium salt powder, and melamine cyanurate powder. The calcium salt powder is one of calcium oxalate and calcium citrate; The composite synergist is composed of zirconate powder and borate powder.

2. The starch-based, pore-expanding, high-chlorine-capacity, long-lasting, high-temperature dechlorinating agent according to claim 1, characterized in that: The zirconate powder is one or a mixture of any two or more of potassium zirconate, calcium zirconate, lithium zirconate, magnesium aluminum zirconate, aluminum zirconate, strontium zirconate, and zinc zirconate in any mass ratio; The borate powder is one or a mixture of any two or more of zinc borate, calcium borate, calcium metaborate, magnesium borate, and aluminum borate in any mass ratio; In the calcium hydroxide suspension, the mass ratio of calcium hydroxide to water is 33~57:100; The mass ratio of the calcium hydroxide suspension to 2,4,6-tris(aminohexanoic acid)-1,3,5-triazine is 150~290:17~97; The particle size of the nano-calcium carbonate is 10~100nm; The mass ratio of the complexed calcium hydroxide, modified hydroxyapatite, composite inorganic binder, reinforcing and toughening whiskers, composite pore-forming agent, composite synergist, nano calcium carbonate, and water is 250~450:60~160:25~60:4~12:13~45:6~30:120~300:330~660.

3. The starch-based, pore-expanding, high-chlorine-capacity, long-lasting, high-temperature dechlorinating agent according to claim 1, characterized in that: The mass ratio of the potassium silicate aqueous solution, silica sol, and pseudoboehmite is 30~90:5~20:7~15; The potassium silicate aqueous solution contains 15-25 wt% potassium silicate and has a modulus of 1.5-3. The silica sol has a solid content of 20-30 wt%, a particle size of 10-100 nm, and a pH value of 8-10. The pseudoboehmite has an alumina content of 65-80 wt% and a gel solubility of 95-99%.

4. The starch-based, pore-expanding, high-chlorine-capacity, long-lasting, high-temperature dechlorinating agent according to claim 1, characterized in that: The potassium titanate whiskers have a diameter of 0.5~10μm and a length of 5~30μm; The mass ratio of starch, calcium salt powder, and melamine cyanurate powder is 30~100:10~40:4~15; The particle size of the calcium salt powder is 0.1~6μm; The particle size of the melamine cyanurate powder is 0.1~10μm.

5. The starch-based, pore-expanding, high-chlorine-capacity, long-lasting, high-temperature dechlorinating agent according to claim 1, characterized in that: The mass ratio of zirconate powder to borate powder is 10~60:67~213; The zirconate powder has a particle size of 0.5~8μm; The borate powder has a particle size of 0.5~8μm.

6. The preparation method of the starch-based pore-expanding, high-chlorine-capacity, long-lasting, high-temperature dechlorinating agent according to claim 1, characterized in that: The preparation method of the starch-based pore-expanding high-chlorine-capacity long-acting high-temperature dechlorination agent includes four steps: preparing complex-coated calcium hydroxide, preparing modified hydroxyapatite, molding, and calcination. The molding process involves, according to the raw material composition and mass ratio of the starch-based pore-expanding high-chlorine-capacity long-acting high-temperature dechlorinating agent, first placing water, reinforcing and toughening whiskers, composite synergist, and nano-calcium carbonate into a double planetary mixer. After initial stirring and dispersion, complexed and coated calcium hydroxide, composite inorganic binder, and composite pore-forming agent are added. After further stirring and dispersion until uniform, modified hydroxyapatite is added. After stirring and dispersion again until uniform, a slurry is obtained. The slurry is then transferred into a twin-screw extruder and extruded to obtain long strip-shaped particles, which are then dried to obtain the molded dechlorinating agent granules.

7. The preparation method of the starch-based pore-expanding, high-chlorine-capacity, long-lasting, high-temperature dechlorinating agent according to claim 6, characterized in that: The calcination process involves calcining the original dechlorinating agent particles at 350-520°C for 3-6 hours, followed by cooling to room temperature to obtain a starch-based, pore-expanding, high-chlorine-capacity, long-lasting, high-temperature dechlorinating agent.

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