An environment-friendly catalyst for promoting efficient and clean combustion of pulverized coal and a preparation method thereof

Abstract

The present invention discloses an environment-friendly catalyst for promoting efficient and clean combustion of pulverized coal and its preparation method, belonging to the technical field of catalysts. Among them, the catalyst has a multi-layer core-shell structure. Specifically, the inner layer is FeCo@SiO2 core-shell particles, and the outer layer is a Co-Ce-O / graphene active layer. By innovatively designing the multi-layer core-shell structure, the present invention provides magnetic protection with the inner layer of FeCo@SiO2 core-shell particles and strengthens the catalytic performance with the outer layer of Co-Ce-O / graphene active layer, successfully breaking through the traditional technical bottleneck. Experiments show that the catalyst prepared by the present invention has reached the leading level in the industry in key indicators such as combustion efficiency, inhibition of heavy metal dissolution, and cycle stability, providing a practical solution for coal-fired power plants to achieve ultra-low emissions.

Description

Technical Field

[0001] The present invention belongs to the technical field of catalysts, and particularly relates to an environment-friendly catalyst for promoting efficient and clean combustion of pulverized coal and a preparation method thereof. Background Art

[0002] As the core method of China's energy supply, coal-fired power generation has problems such as unburned carbon (fly ash carbon content ≥ 5%) and pollutant emissions that are easily generated during the combustion process. Traditional commercial catalysts (such as V 2 O 5 -WO 3 / TiO 2 ) can partially improve the combustion efficiency, but still have the following significant defects:

[0003] Low combustion efficiency: Limited by the uneven dispersion of active components and insufficient thermal stability, the combustion efficiency of pulverized coal by existing catalysts is generally lower than 90%, resulting in a large amount of unburned carbon residue, which not only wastes resources but also exacerbates the emissions of PM2.5 and CO 2 emissions.

[0004] High recovery cost: Commercial catalysts need to be recovered through complex water washing and filtration processes, with a large water consumption (10 - 15 tons of water are consumed per ton of catalyst), and the washing wastewater contains high-concentration heavy metal ions, and the treatment cost is as high as more than 5000 yuan per ton, seriously restricting its economic feasibility.

[0005] Outstanding environmental risks: The accumulation of unburned carbon will reduce the boiler thermal efficiency, and the dissolution of heavy metals (such as V 2 O 5 catalyst dissolution amount > 10 mg / L) will cause persistent pollution to soil and water bodies.

[0006] In view of the above problems, there is an urgent need to develop an environment-friendly catalyst with high catalytic activity. Summary of the Invention

[0007] Through innovative design of a multi-layer core-shell structure, the present invention provides magnetic protection with the inner layer of FeCo@SiO 2 core-shell particles and strengthens the catalytic performance with the outer layer of Co-Ce-O / graphene active layer, successfully breaking through the traditional technical bottleneck. Experiments show that the catalyst prepared by the present invention has reached the leading level in the industry in key indicators such as combustion efficiency, inhibition of heavy metal dissolution, and cycle stability, providing a practical solution for coal-fired power plants to achieve ultra-low emissions. Specifically, the object of the present invention can be achieved by the following technical solutions:

[0008] An environment-friendly catalyst for promoting efficient and clean combustion of pulverized coal, the catalyst is a multi-layer core-shell structure; the multi-layer core-shell structure includes an inner layer and an outer layer; the inner layer is FeCo@SiO 2Core-shell particles; the outer layer is a Co-Ce-O / graphene active layer.

[0009] Further, the FeCo@SiO 2 The core-shell particles are prepared by the following steps:

[0010] S1: Dissolve FeCl 3 ·6H 2 O, CoCl 2 ·6H 2 O in ethylene glycol, then add 0.1 mol / L NaBH 4 solution, stir at 80 - 85 °C for 2 - 4 h, filter to obtain FeCo nanoparticles;

[0011] S2: Disperse the FeCo nanoparticles in an ethanol solution with a mass fraction of 75%, then add tetraethyl orthosilicate and ammonia water with a mass fraction of 25%, stir at 50 - 55 °C for 5 - 6 h, filter to obtain FeCo@SiO 2 core-shell particles.

[0012] Further, the dosage ratio of FeCl 3 ·6H 2 O, CoCl 2 ·6H 2 O, ethylene glycol, and 0.1 mol / L NaBH 4 solution is 54 - 55 g:42 - 45 g:500 mL:0.7 - 1.0 L.

[0013] Further, the dosage ratio of the FeCo nanoparticles, the ethanol solution with a mass fraction of 75%, tetraethyl orthosilicate, and ammonia water with a mass fraction of 25% in S2 is 30 g:200 mL:8.4 - 8.5 g:10 - 12 mL.

[0014] Further, the preparation method of the catalyst includes the following steps:

[0015] Add FeCo@SiO 2 core-shell particles and graphene oxide to pure water, and ultrasonically disperse for 1 - 2 h, then add cerium nitrate and urea, carry out hydrothermal reaction at 80 - 90 °C for 8 - 10 h to obtain a mixture, then dry the mixture at 120 - 150 °C, and then calcine at 740 - 750 °C in an argon atmosphere for 2 - 3 h. After calcination, cool to room temperature to obtain the catalyst.

[0016] Further, the specific surface area of the graphene oxide is 800 m 2 / g.

[0017] Further, the frequency of the ultrasonic dispersion is 40 kHz and the power is 500 W.

[0018] Further, the dosage ratio of the pure water, FeCo@SiO 2 core-shell particles, graphene oxide, cerium nitrate and urea is 500 mL: 25 g: 20 - 25 g: 15.5 - 16.0 g: 21 - 22 g.

[0019] Advantages of the present invention:

[0020] The present invention provides an environment-friendly catalyst for promoting the efficient and clean combustion of pulverized coal and a preparation method thereof. The catalyst prepared by the present invention has a multi-layer core-shell structure. Among them, the inner layer is FeCo@SiO 2 core-shell; the outer layer is a Co-Ce-O / graphene active layer. The catalyst prepared by the present invention has the following advantages:

[0021] (1) High-efficiency catalytic combustion: The Co-Ce-O / graphene active layer significantly improves the combustion efficiency of pulverized coal to ≥98%, far exceeding that of commercial catalysts (<90%).

[0022] (2) Environmental protection and safety: The SiO 2 shell layer reduces the dissolution amount of Fe 2+ and Co 2+ to below 0.05 mg / L, far lower than that of the shell-less control (6.87 mg / L), effectively avoiding heavy metal pollution.

[0023] (3) Convenience of magnetic recovery: The FeCo nanoparticles in the inner layer FeCo@SiO 2 core-shell are magnetic materials and have a high Curie temperature (>900 °C). In the circulating fluidized bed mode, the low-temperature combustion of pulverized coal (850 - 900 °C) can be controlled through material circulation. On this basis, the FeCo nano-core of the catalyst prepared by the present invention can maintain effective magnetism. After promoting the combustion of pulverized coal, the catalyst can be magnetically recovered, improving the recovery efficiency of the catalyst.

[0024] (4) High-temperature stability: The Co-Ce-O layer and the SiO 2 shell layer act synergistically. Among them, the SiO 2 shell layer improves the high-temperature stability of FeCo magnetism through coating. Co-Ce-O has excellent high-temperature resistance, and the Co-Ce-O layer is combined with SiO 2 through Si-O-Co bonds to avoid falling off from each other. Thus, after 10 magnetic separation-pickling cycles, the combustion efficiency of the catalyst for promoting the combustion of pulverized coal is always ≥95% and the combustion efficiency decay rate ≤2.5%.

[0025] (5) Industrialization potential: The preparation process of the present invention is simple and the raw material cost is low, which is suitable for large-scale application in the ultra-low emission transformation of coal-fired power plants. Brief Description of the Drawings

[0026] The present invention will be further described below with reference to the drawings.

[0027] Figure 1 is the TEM image of the FeCo@SiO 2 core-shell particles in Example 2 of the present invention;

[0028] Figure 2 is the TEM image of the environment-friendly catalyst for promoting the efficient and clean combustion of pulverized coal in Example 2 of the present invention. Detailed Embodiments

[0029] The technical solutions in the embodiments of the present invention will be clearly and completely described below in conjunction with the embodiments of the present invention. Obviously, the described embodiments are only a part of the embodiments of the present invention, rather than all of the embodiments. All other embodiments obtained by those of ordinary skill in the art based on the embodiments of the present invention without creative efforts shall fall within the protection scope of the present invention. Example 1

[0030] A preparation method of an environment-friendly catalyst for promoting the efficient and clean combustion of pulverized coal, comprising the following steps:

[0031] S1: Dissolve 54 g of ferric chloride (FeCl 3 ·6H 2 O), 42 g of cobalt chloride (CoCl 2 ·6H 2 O) in 500 mL of ethylene glycol, then add 0.7 L of 0.1 mol / L NaBH 4 solution thereto, heat the system to 80 °C, then stir at a constant temperature for 2 h, and then filter to obtain FeCo nanoparticles;

[0032] S2: Disperse 30 g of the FeCo nanoparticles prepared in S1 above in 200 mL of an ethanol solution with a mass fraction of 75%, then add 8.4 g of tetraethyl orthosilicate and 10 mL of ammonia water with a mass fraction of 25% thereto, heat the system to 50 °C, then stir at a constant temperature for 5 h, and then filter to obtain FeCo@SiO 2 core-shell particles;

[0033] S3: Add 25 g of the FeCo@SiO 2 core-shell particles prepared in S2 above and 20 g of graphene oxide (specific surface area 800 m 2 / g), and ultrasonically disperse (40 kHz, 500 W) for 1 h. Then add 15.5 g of cerium nitrate (Ce(NO 3 ) 3 ·6H 2 O) and 21 g of urea (CO(NH 2 ) 2 ). Heat the system to 80 °C, and then carry out a hydrothermal reaction at a constant temperature for 8 h to form a Co-Ce-O / graphene active layer, obtaining a mixture. Then dry the mixture at 120 °C, and then calcine it in an argon atmosphere at 740 °C for 2 h. After the calcination is completed, cool it to room temperature to obtain an environmentally friendly catalyst for promoting the efficient and clean combustion of pulverized coal. Example 2

[0034] A preparation method of an environmentally friendly catalyst for promoting the efficient and clean combustion of pulverized coal, comprising the following steps:

[0035] S1: Dissolve 54 g of ferric chloride (FeCl 3 ·6H 2 O), 42.6 g of cobalt chloride (CoCl 2 ·6H 2 O) in 500 mL of ethylene glycol. Then add 0.8 L of 0.1 mol / L NaBH 4 solution. Heat the system to 80 °C, and then stir at a constant temperature for 4 h. Then filter to obtain FeCo nanoparticles;

[0036] S2: Disperse 30 g of the FeCo nanoparticles prepared in S1 above in 200 mL of an ethanol solution with a mass fraction of 75%. Then add 8.5 g of tetraethyl orthosilicate and 12 mL of ammonia water with a mass fraction of 25%. Heat the system to 50 °C, and then stir at a constant temperature for 6 h. Then filter to obtain FeCo@SiO 2 core-shell particles. The TEM electron microscope characterization of the FeCo@SiO 2 core-shell particles is shown in the appendix Figure 1 ;

[0037] S3: Add 25 g of the FeCo@SiO 2 core-shell particles prepared in S2 above and 25 g of graphene oxide (specific surface area 800 m 2 / g) to 500 mL of pure water, and ultrasonically disperse (40 kHz, 500 W) for 2 h. Then add 15.5 g of cerium nitrate (Ce(NO 3 ) 3 ·6H 2 O) and 21.5 g of urea (CO(NH 2 ) 2), the system is heated to 80 °C, and then subjected to hydrothermal reaction at a constant temperature for 10 h to form a Co-Ce-O / graphene active layer, obtaining a mixture. Then the mixture is dried at 120 °C, and then calcined in an argon atmosphere at 750 °C for 3 h. After the calcination is completed, it is cooled to room temperature to obtain an environmentally friendly catalyst for promoting the efficient and clean combustion of pulverized coal. The TEM electron microscopy characterization of the catalyst is shown in the appendix Figure 2 . Example 3

[0038] A preparation method of an environmentally friendly catalyst for promoting the efficient and clean combustion of pulverized coal, comprising the following steps:

[0039] S1: Dissolve 55 g of ferric chloride (FeCl 3 ·6H 2 O), 45 g of cobalt chloride (CoCl 2 ·6H 2 O) in 500 mL of ethylene glycol, and then add 1.0 L of 0.1 mol / L NaBH 4 solution. The system is heated to 85 °C, and then stirred at a constant temperature for 4 h, and then filtered to obtain FeCo nanoparticles;

[0040] S2: Disperse 30 g of the FeCo nanoparticles prepared in S1 above in 200 mL of an ethanol solution with a mass fraction of 75%, and then add 8.5 g of tetraethyl orthosilicate and 12 mL of ammonia water with a mass fraction of 25%. The system is heated to 55 °C, and then stirred at a constant temperature for 6 h, and then filtered to obtain FeCo@SiO 2 core-shell particles;

[0041] S3: Add 25 g of the FeCo@SiO 2 core-shell particles prepared in S2 above and 25 g of graphene oxide (specific surface area 800 m 2 / g) to 500 mL of pure water, and ultrasonically disperse (40 kHz, 500 W) for 2 h. Then add 16.0 g of cerium nitrate (Ce(NO 3 ) 3 ·6H 2 O) and 22 g of urea (CO(NH 2 ) 2 ). The system is heated to 90 °C, and then subjected to hydrothermal reaction at a constant temperature for 10 h to form a Co-Ce-O / graphene active layer, obtaining a mixture. Then the mixture is dried at 150 °C, and then calcined in an argon atmosphere at 750 °C for 3 h. After the calcination is completed, it is cooled to room temperature to obtain an environmentally friendly catalyst for promoting the efficient and clean combustion of pulverized coal.

[0042] Comparative Example 1

[0043] Comparative Example 1 is the control group of Example 2, and there is no SiO 2 shell layer. The preparation process is as follows:

[0044] A preparation method of an environmentally friendly catalyst for promoting the efficient and clean combustion of pulverized coal includes the following steps:

[0045] S1: Dissolve 54 g of ferric chloride (FeCl 3 ·6H 2 O), 42.6 g of cobalt chloride (CoCl 2 ·6H 2 O) in 500 mL of ethylene glycol, then add 0.8 L of 0.1 mol / L NaBH 4 solution, heat the system to 80 °C, then stir at a constant temperature for 4 h, and then filter to obtain FeCo nanoparticles;

[0046] S2: Mix 25 g of the FeCo nanoparticles prepared in S1 above with 25 g of graphene oxide (specific surface area 800 m 2 / g), ultrasonically disperse (40 kHz, 500 W) for 2 h, then add 15.5 g of cerium nitrate (Ce(NO 3 ) 3 ·6H 2 O) and 21.5 g of urea (CO(NH 2 ) 2 ), heat the system to 80 °C, then carry out hydrothermal reaction at a constant temperature for 10 h to form a Co-Ce-O / graphene active layer, obtain a mixture, then dry the mixture at 120 °C, and then calcine it in an argon atmosphere at 750 °C for 3 h. After calcination, cool it to room temperature to obtain an environmentally friendly catalyst for promoting the efficient and clean combustion of pulverized coal.

[0047] Comparative Example 2

[0048] Comparative Example 2 is the control group of Example 2, and there is no Co-Ce-O layer in Comparative Example 2. The preparation process is as follows:

[0049] A preparation method of an environmentally friendly catalyst for promoting the efficient and clean combustion of pulverized coal includes the following steps:

[0050] S1: Dissolve 54 g of ferric chloride (FeCl 3 ·6H 2 O), 42.6 g of cobalt chloride (CoCl 2 ·6H 2 O) in 500 mL of ethylene glycol, then add 0.8 L of 0.1 mol / L NaBH 4 solution, heat the system to 80 °C, then stir at a constant temperature for 4 h, and then filter to obtain FeCo nanoparticles;

[0051] S2: Disperse 30 g of the FeCo nanoparticles prepared in S1 above in 200 mL of an ethanol solution with a mass fraction of 75%, then add 8.5 g of tetraethyl orthosilicate and 12 mL of ammonia water with a mass fraction of 25% thereto, heat the system to 50 °C, then stir at a constant temperature for 6 h, and then filter to obtain FeCo@SiO 2 core-shell particles;

[0052] S3: Add 25 g of the FeCo@SiO 2 core-shell particles prepared in S2 above and 25 g of graphene oxide (specific surface area 800 m 2 / g) to 500 mL of pure water, and ultrasonically disperse (40 kHz, 500 W) for 2 h. Then heat the system to 80 °C and carry out a hydrothermal reaction at a constant temperature for 10 h to obtain a mixture. Then dry the mixture at 120 °C, and then calcine it in an argon atmosphere at 750 °C for 3 h. After calcination, cool it to room temperature to obtain an environment-friendly catalyst for promoting the efficient and clean combustion of pulverized coal.

[0053] Test Example 1

[0054] Perform performance tests on the catalysts prepared in Examples 1 to 3 and Comparative Examples 1 to 2. The performance test process is as follows, and the test results are shown in Table 1:

[0055] (1) Heavy metal leaching test: Immerse the catalyst in a nitric acid solution with pH = 3 for 24 h, and detect the concentration of leached ions by ICP-MS.

[0056] (2) Combustion efficiency test: Mix pulverized coal (median particle size 75 μm) and the catalyst in a mass ratio of 100:1, place them in a tubular furnace, introduce air, heat to 800 °C at a rate of 10 °C / min, then burn at a constant temperature for 30 min. After completion, stop introducing air and heating, and then naturally cool to room temperature. Weigh the mass of the combustion residue, and calculate the combustion efficiency (η) according to the following formula:

[0057] η = (1 - mass of residue / initial mass) × 100%.

[0058] (3) High-temperature resistance performance test: Use a vibrating sample magnetometer (VSM) to measure the initial saturation magnetization intensity (Ms) of the catalyst, then carry out the combustion efficiency test. After weighing, measure Ms again and calculate the magnetic attenuation rate: ΔMs = [(Ms initial - Ms after treatment) / Ms initial] × 100%.

[0059] (4) Cyclic stability test: The catalyst was continuously subjected to 10 cycles of "combustion efficiency test → magnetic separation and recovery → pickling (hydrochloric acid solution with pH = 3, 30 min) → drying (60 °C, 6 h)". Calculate the combustion efficiency of the pulverized coal after 10 cycles (the calculation method is the same as above), and calculate the combustion efficiency decay rate:

[0060] Δη = [(ηinitial - ηafter 10 cycles) / ηinitial] × 100%.

[0061] Table 1 Test results

[0062]

[0063] From the data in Table 1, it can be obtained that:

[0064] (1) The role of the SiO 2 shell layer:

[0065] a. Anti-oxidation and magnetic protection: In Comparative Example 1 (without the SiO 2 shell layer), the dissolution amounts of Fe 2+ and Co 2+ were 6.87 mg / L and 8.51 mg / L respectively, which were much higher than those in Example 2 (0.05 mg / L and 0.08 mg / L), indicating that the SiO 2 shell layer effectively isolates the FeCo nanoparticles from the external environment and significantly inhibits metal oxidation and ion dissolution.

[0066] b. High-temperature stability: The magnetic decay rate of Comparative Example 1 was as high as 21.7%, while that of Example 2 was only 4.5%, indicating that the SiO 2 shell layer stabilizes the FeCo magnetism at high temperatures and avoids magnetic loss caused by oxidation.

[0067] (2) The role of the Co-Ce-O layer:

[0068] a. Catalytic activity improvement: The combustion efficiency of Comparative Example 2 (without the Co-Ce-O layer) was only 78.7%, while that of Example 2 reached 99.5%, indicating that the Co-Ce-O layer is the key active component for efficient combustion of pulverized coal.

[0069] b. Enhanced structural stability: The Co-Ce-O layer is combined with the SiO 2 shell layer through Si-O-Co bonds (Example 2), preventing the outer layer from falling off, so that the combustion efficiency still remains 97.4% (decay rate 2.1%) after 10 cycles. In Comparative Example 2, the catalytic activity is insufficient and the combustion efficiency cannot be improved.

[0070] (3) Synergistic effect:

[0071] a. Dual protection mechanism: SiO 2The shell layer provides a physical barrier to prevent the oxidation of FeCo, and the Co-Ce-O layer enhances the overall structural stability through chemical bonding. The two together reduce the metal leaching (the Fe leaching amount in Example 2 is only 0.7% of that in Comparative Example 1). 2+ The leaching amount is only 0.7% of that in Comparative Example 1.

[0072] b. High-temperature performance optimization: The Co-Ce-O layer has both catalytic activity and high-temperature resistance (the magnetic attenuation is <5% at 800 °C), and together with the SiO 2 shell layer, it ensures that the catalyst remains highly efficient and stable in a high-temperature combustion environment.

[0073] c. Recycling economy: The magnetic recovery of FeCo nanoparticles and the catalytic activity of the Co-Ce-O layer act synergistically, enabling the catalyst to still maintain a combustion efficiency of ≥95% after 10 cycles, and the recycling cost is significantly reduced.

[0074] It should be noted that in this article, terms such as "including", "comprising" or any other variants thereof are intended to cover non-exclusive inclusion, so that a process, method, article or device including a series of elements not only includes those elements, but also includes other elements not explicitly listed, or further includes elements inherent to such a process, method, article or device.

[0075] Although the embodiments of the present invention have been shown and described, for those of ordinary skill in the art, it can be understood that various changes, modifications, substitutions and variations can be made to these embodiments without departing from the principles and spirit of the present invention. The scope of the present invention is defined by the appended claims and their equivalents.

Claims

1. An environmentally friendly catalyst for promoting efficient and clean combustion of pulverized coal, characterized in that: The catalyst is a multi-layer core-shell structure, and the multi-layer core-shell structure includes an inner layer and an outer layer; The inner layer is FeCo@SiO2 core-shell particles; The outer layer is a Co-Ce-O / graphene active layer; The method for preparing the environmentally friendly catalyst comprises the following steps: FeCo@SiO2 core-shell particles and graphene oxide are added to pure water and ultrasonically dispersed for 1 to 2 hours, and then cerium nitrate and urea are added thereto, and a hydrothermal reaction is carried out at 80 to 90° C. for 8 to 10 hours to obtain a mixture, and then the mixture is dried at 120 to 150° C., and then calcined at 740 to 750° C. in an argon atmosphere for 2 to 3 hours. After calcination, the mixture is cooled to room temperature to obtain the catalyst.

2. The environmentally friendly catalyst for promoting efficient and clean combustion of pulverized coal according to claim 1, characterized in that: The FeCo@SiO2 core-shell particles are prepared by the following steps: S1: Dissolve FeCl3·6H2O and CoCl2·6H2O in ethylene glycol, add 0.1 mol / L NaBH4 solution, stir at 80-85°C for 2-4h, filter and obtain FeCo nanoparticles; S2: Disperse FeCo nanoparticles in 75% by mass ethanol solution, add ethyl orthosilicate and 25% by mass ammonia water, stir at 50-55°C for 5-6h, filter, and obtain FeCo@SiO2 core-shell particles.

3. The environmentally friendly catalyst for promoting efficient and clean combustion of pulverized coal according to claim 2, characterized in that: The dosage ratio of FeCl3·6H2O, CoCl2·6H2O, ethylene glycol, and 0.1 mol / L NaBH4 solution in S1 is 54-55 g:42-45 g:500 mL:0.7-1.0 L.

4. The environmentally friendly catalyst for promoting efficient and clean combustion of pulverized coal according to claim 2, characterized in that: The dosage ratio of the FeCo nanoparticles, the ethanol solution with a mass fraction of 75%, the ethyl orthosilicate, and the ammonia water with a mass fraction of 25% described in S2 is 30g:200mL:8.4-8.5g:10-12mL.

5. A method for preparing an environmentally friendly catalyst for promoting efficient and clean combustion of pulverized coal according to any one of claims 1 to 4, characterized in that: The following steps are involved: FeCo@SiO2 core-shell particles and graphene oxide are added to pure water and ultrasonically dispersed for 1 to 2 hours, and then cerium nitrate and urea are added thereto, and a hydrothermal reaction is carried out at 80 to 90° C. for 8 to 10 hours to obtain a mixture, and then the mixture is dried at 120 to 150° C., and then calcined at 740 to 750° C. in an argon atmosphere for 2 to 3 hours. After calcination, the mixture is cooled to room temperature to obtain the catalyst.

6. The method for preparing an environmentally friendly catalyst for promoting efficient and clean combustion of pulverized coal according to claim 5, characterized in that: The specific surface area of ​​the graphene oxide is 800 m 2 / g.

7. The method for preparing an environmentally friendly catalyst for promoting efficient and clean combustion of pulverized coal according to claim 5, characterized in that: The frequency of the ultrasonic dispersion is 40 kHz and the power is 500 W.

8. The method for preparing an environmentally friendly catalyst for promoting efficient and clean combustion of pulverized coal according to claim 5, characterized in that: The usage ratio of the pure water, the FeCo@SiO2 core-shell particles, the graphene oxide, the cerium nitrate and the urea is 500 mL: 25 g: 20-25 g: 15.5-16.0 g: 21-22 g.

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