Potassium carbonate / sodium carbonate loaded-sulfur self-doped activated carbon for capturing CO2 in coal-fired flue gas and preparation method of activated carbon

Abstract

The invention discloses potassium carbonate / sodium carbonate loaded-sulfur self-doped activated carbon for capturing CO2 in coal-fired flue gas and a preparation method of the activated carbon. The preparation method of the activated carbon comprises the following steps: crushing high-sulfur coal to form pulverized coal particles, and carrying out acid pickling treatment; mixing and doping the pulverized coal particles subjected to acid pickling with potassium hydroxide, carbonizing, and performing pyrolysis activation to form coarse activated carbon; performing ultrasonic cleaning on the coarse activated carbon, and drying to obtain sulfur-doped activated carbon; placing the sulfur-doped activated carbon in a vacuum impregnation device, vacuumizing to form a negative pressure environment, atomizing a potassium carbonate / sodium carbonate solution, and introducing the atomized potassium carbonate / sodium carbonate solution into a vacuum impregnation cavity; and drying to obtain the potassium carbonate / sodium carbonate loaded-sulfur self-doped activated carbon. According to the potassium carbonate / sodium carbonate loaded-sulfur self-doped activated carbon for capturing CO2 in coal-fired flue gas in the embodiment of the invention, the preparation cost is reduced, the adsorption selectivity and adsorption capacity of the activated carbon are enhanced, and the adverse effect of water vapor on the physical adsorption process of CO2 can be reduced.

Description

Technical Field

[0001] The present invention relates to the technical field of flue gas purification, and in particular to a potassium carbonate / sodium carbonate loaded-sulfur self-doped activated carbon for capturing CO2 from coal-fired flue gas and a preparation method thereof. Background Art

[0002] CO2 capture technologies for coal-fired power plants are categorized into pre-combustion capture, in-combustion capture, and post-combustion capture. Post-combustion capture uses adsorbents / absorbents to selectively adsorb CO2 from coal-fired flue gas. This technology has attracted considerable attention due to its minimal modification requirements and low cost for existing coal-fired power plants. Solid CO2 adsorbents primarily include zeolites, multi-molecular sieves, MOFs, and activated carbon. Compared to other solid adsorbents, activated carbon offers advantages such as strong adsorption properties, a simple preparation process, and easy regeneration. During CO2 capture using activated carbon materials, due to their inherent hydrophilicity, water vapor and CO2 compete for adsorption on the activated carbon's adsorption sites, reducing its CO2 adsorption capacity.

[0003] Therefore, the activated carbon used for capturing CO2 from coal-fired flue gas in the related art has the problem of poor ability to adsorb CO2 due to the influence of water vapor. Summary of the Invention

[0004] The present invention aims to address at least one of the technical problems existing in the prior art. To this end, one object of the present invention is to provide a method for preparing potassium / sodium carbonate-loaded, sulfur-doped activated carbon for CO2 capture from coal-fired flue gas. The activated carbon produced by this method can reduce the adverse effects of water vapor on the CO2 physical adsorption process.

[0005] The present invention also provides a potassium carbonate / sodium carbonate loaded-sulfur self-doped activated carbon for capturing CO2 from coal-fired flue gas, which is prepared by the above preparation method.

[0006] According to the first embodiment of the present invention, a method for preparing potassium carbonate / sodium carbonate-loaded sulfur self-doped activated carbon for capturing CO2 from coal-fired flue gas comprises:

[0007] Step (1), crushing and screening the high-sulfur coal to form coal powder particles, and performing acid washing on the coal powder particles;

[0008] Step (2), mixing the acid-washed pulverized coal particles with potassium hydroxide to form a mixture, carbonizing the mixture under a nitrogen atmosphere, and then pyrolyzing and activating the mixture to form crude activated carbon;

[0009] Step (3), ultrasonically cleaning and drying the crude activated carbon to obtain sulfur-doped activated carbon;

[0010] Step (4), placing the sulfur-doped activated carbon in a vacuum impregnation device, evacuating the vacuum impregnation chamber where the sulfur-doped activated carbon is located to form a negative pressure environment, and atomizing the impregnation solution and passing it into the vacuum impregnation chamber, wherein the impregnation solution is a potassium carbonate / sodium carbonate solution;

[0011] Step (5), drying the impregnated sulfur-doped activated carbon to obtain the potassium carbonate / sodium carbonate-loaded sulfur self-doped activated carbon.

[0012] According to the preparation method of potassium carbonate / sodium carbonate loaded-sulfur self-doped activated carbon for capturing CO2 from coal-fired flue gas according to the embodiment of the present invention, high-sulfur coal is selected as the raw material of activated carbon, and the sulfur element inherent in the high-sulfur coal is used for doping and modification without introducing an external sulfur source, thereby reducing the preparation cost. The formation of chemical bonds between the sulfur element and the surface of the activated carbon is conducive to the formation of a multi-level pore structure of the activated carbon, thereby enhancing the adsorption selectivity and adsorption capacity of the activated carbon. Potassium carbonate / sodium carbonate is loaded on the activated carbon through vacuum impregnation treatment, making the loading process of potassium carbonate / sodium carbonate more directional and controllable, so that potassium carbonate / sodium carbonate can be uniformly attached to the outer mesopores of the activated carbon without blocking the flow pores of the activated carbon. The activated carbon loaded with potassium carbonate / sodium carbonate has a multi-level CO2 adsorption capacity in which chemical adsorption of the outer mesopores and physical adsorption of the inner micropores coexist, and can reduce the adverse effects of water vapor on the CO2 physical adsorption process.

[0013] According to some embodiments of the present invention, in step (1), the particle size of the coal powder particles is 70-100 mesh.

[0014] According to some embodiments of the present invention, in step (1), the pulverized coal particles are subjected to an acid wash treatment, comprising: using hydrochloric acid to carry out an acid wash treatment on the pulverized coal particles, wherein the concentration of the hydrochloric acid is 2%-10%.

[0015] According to some embodiments of the present invention, in step (1), the pulverized coal particles are subjected to an acid wash treatment, including stirring and oscillating during the acid wash treatment, and the acid wash treatment time is not less than 1 hour.

[0016] According to some embodiments of the present invention, in step (2), the mass ratio of the coal powder particles to potassium hydroxide is 1:3-4, and the acid-washed coal powder particles are mixed and doped with potassium hydroxide by ball milling or solution impregnation.

[0017] According to some embodiments of the present invention, in step (2), the mixture is carbonized under a nitrogen atmosphere, comprising: a carbonization temperature of 400-450° C., and a carbonization time of 1-1.5 h.

[0018] According to some embodiments of the present invention, in step (2), the pyrolysis activation includes: performing pyrolysis activation under a nitrogen atmosphere, the pyrolysis activation temperature is 750-850° C., and the pyrolysis activation time is 1 h-1.5 h.

[0019] According to some embodiments of the present invention, in step (4), the pressure of the vacuum impregnation chamber after the vacuum treatment is ≤1.5 bar;

[0020] According to some embodiments of the present invention, the molar concentration of the potassium carbonate / sodium carbonate solution is 0.2 mol / L.

[0021] According to some embodiments of the present invention, in step (4), the median size of the droplets formed by the atomization of the impregnation solution is 2-5 μm, which can be adjusted to 1-8 μm by a controller according to the viscosity of the liquid.

[0022] According to some embodiments of the present invention, in step (5), the drying temperature is 100° C., the drying time is 1 hour, and nitrogen is continuously introduced during the drying process.

[0023] According to some embodiments of the present invention, the components of the coal-fired flue gas include nitrogen, carbon dioxide, water vapor and oxygen, wherein the volume fraction of nitrogen is 68-75%, the volume fraction of carbon dioxide is 12-15%, the volume fraction of water vapor is 0-10%, and the volume fraction of oxygen is 3-5%.

[0024] According to the second aspect of the present invention, the potassium carbonate / sodium carbonate loaded-sulfur self-doping activated carbon for capturing CO2 from coal-fired flue gas is prepared by the preparation method of the potassium carbonate / sodium carbonate loaded-sulfur self-doping activated carbon for capturing CO2 from coal-fired flue gas according to the first aspect of the present invention.

[0025] According to the potassium carbonate / sodium carbonate loaded-sulfur self-doped activated carbon for capturing CO2 from coal-fired flue gas according to the embodiment of the present invention, high-sulfur coal is selected as the raw material of the activated carbon. Without introducing an external sulfur source, the sulfur element of the high-sulfur coal is used for doping and modification, thereby reducing the preparation cost. The formation of chemical bonds between the sulfur element and the surface of the activated carbon is conducive to the formation of a multi-level pore structure of the activated carbon, thereby enhancing the adsorption selectivity and adsorption capacity of the activated carbon. The activated carbon loaded with potassium carbonate / sodium carbonate has a multi-level CO2 adsorption capacity with the coexistence of chemical adsorption of the outer mesopores and physical adsorption of the inner micropores, which can reduce the adverse effects of water vapor on the CO2 physical adsorption process.

[0026] Additional aspects and advantages of the present invention will be set forth in part in the description which follows and, in part, will be obvious from the description which follows, or may be learned by practice of the present invention. BRIEF DESCRIPTION OF THE DRAWINGS

[0027] The above and / or additional aspects and advantages of the present invention will become apparent and readily understood from the following description of the embodiments with reference to the accompanying drawings, in which:

[0028] Figure 1 The present invention is a schematic flow chart of a method for preparing potassium carbonate / sodium carbonate loaded-sulfur self-doped activated carbon for capturing CO2 from coal-fired flue gas according to some embodiments of the present invention. DETAILED DESCRIPTION

[0029] The following describes embodiments of the present invention in detail. Examples of the embodiments are shown in the accompanying drawings, wherein the same or similar reference numerals throughout represent the same or similar elements or elements having the same or similar functions. The embodiments described below with reference to the accompanying drawings are exemplary and are intended only to explain the present invention and are not to be construed as limiting the present invention.

[0030] Reference below Figure 1 The present invention describes a method for preparing potassium carbonate / sodium carbonate loaded-sulfur self-doped activated carbon for CO2 capture from coal-fired flue gas according to an embodiment of the present invention.

[0031] According to the first embodiment of the present invention, a method for preparing potassium carbonate / sodium carbonate-loaded sulfur self-doped activated carbon for capturing CO2 from coal-fired flue gas comprises:

[0032] Step (1) crushing and screening high-sulfur coal to form coal powder particles, and then acid-washing the coal powder particles; wherein the high-sulfur coal is coal with a sulfur content of ≥3wt%. By selecting easily available and inexpensive high-sulfur coal as the raw material for activated carbon, the high-sulfur coal is used for doping and modification without introducing an external sulfur source, thereby reducing the preparation cost;

[0033] Step (2), mixing the acid-washed pulverized coal particles with potassium hydroxide to form a mixture, using potassium hydroxide as an activator to improve the adsorption capacity of the activated carbon, carbonizing the mixture under a nitrogen atmosphere, and then pyrolyzing and activating it to form crude activated carbon. By the staged high-temperature treatment of carbonization followed by pyrolysis and activation, the structure of the coal can be pre-carbonized and then pyrolyzed into activated carbon, which is conducive to forming more amorphous carbon, thereby improving the adsorption performance of the activated carbon;

[0034] Step (3), ultrasonically cleaning and drying the crude activated carbon to obtain sulfur-doped activated carbon; the formation of chemical bonds between the sulfur element and the surface of the activated carbon is conducive to the formation of a multi-level pore structure of the activated carbon, thereby enhancing the adsorption selectivity and adsorption capacity of the activated carbon; the SC functional group in the sulfur-doped activated carbon forms a strong acid-base interaction with the acidic CO2 molecule under the action of Lewis acid and base, and at the same time, the large quadrupole moment of the CO2 molecule and the polar site in the sulfur-containing functional group can form a strong pole-pole interaction, thereby improving the selective adsorption capacity of the sulfur-doped activated carbon for CO2 molecules;

[0035] Step (4), placing the sulfur-doped activated carbon in a vacuum impregnation device, and vacuumizing the vacuum impregnation chamber where the sulfur-doped activated carbon is located to form a negative pressure environment, and then atomizing the impregnation solution into the vacuum impregnation chamber, wherein the impregnation solution is a potassium carbonate / sodium carbonate solution; by forming a negative pressure environment in the vacuum impregnation device and then loading the sulfur-doped activated carbon by atomizing the potassium carbonate / sodium carbonate solution, the loading process can be made more directional and controllable, so that the potassium carbonate / sodium carbonate is loaded into the outer mesopores of the activated carbon, thereby preventing the potassium carbonate / sodium carbonate from clogging the flow pores of the activated carbon and improving the uniformity of the potassium carbonate / sodium carbonate loading on the sulfur-doped activated carbon;

[0036] Step (5), drying the impregnated sulfur-doped activated carbon to obtain potassium carbonate / sodium carbonate-loaded sulfur self-doped activated carbon; for example, the process of potassium carbonate / sodium carbonate adsorption-desorption of CO2 is mainly achieved by the two chemical reactions shown in formulas 1.1 and 1.2, where M is Na or K;

[0037] Carbonation reaction: M2CO3(s)+CO2(g)+H2O(g)→2MHCO3(s) (1.1)

[0038] Regeneration reaction: 2MHCO3(s)→M2CO3(s)+CO2(g)+H2O(g)(1.2)

[0039] By selecting low-cost potassium carbonate / sodium carbonate for loading sulfur-doped activated carbon, it is possible to achieve chemical adsorption of water vapor and CO2 through carbonation reaction of potassium carbonate / sodium carbonate in the outer mesopores of the activated carbon in a flue gas environment with high water vapor content, thereby reducing the adverse effect of water vapor on physical adsorption and facilitating the physical adsorption of CO2 in the inner micropores of the activated carbon, thereby forming a multi-level adsorption structure and improving the overall adsorption performance of the activated carbon.

[0040] According to the preparation method of potassium carbonate / sodium carbonate loaded-sulfur self-doped activated carbon for capturing CO2 from coal-fired flue gas according to the embodiment of the present invention, high-sulfur coal is selected as the raw material of activated carbon, and the sulfur element inherent in the high-sulfur coal is used for doping and modification without introducing an external sulfur source, thereby reducing the preparation cost. The formation of chemical bonds between the sulfur element and the surface of the activated carbon is conducive to the formation of a multi-level pore structure of the activated carbon, thereby enhancing the adsorption selectivity and adsorption capacity of the activated carbon. Potassium carbonate / sodium carbonate is loaded on the activated carbon through vacuum impregnation treatment, making the loading process of potassium carbonate / sodium carbonate more directional and controllable, so that potassium carbonate / sodium carbonate can be uniformly attached to the outer mesopores of the activated carbon without blocking the flow pores of the activated carbon. The activated carbon loaded with potassium carbonate / sodium carbonate has a multi-level CO2 adsorption capacity in which chemical adsorption of the outer mesopores and physical adsorption of the inner micropores coexist, and can reduce the adverse effects of water vapor on the CO2 physical adsorption process.

[0041] According to some embodiments of the present invention, in step (1), the particle size of the pulverized coal particles is 70-100 mesh. For example, the particle size of the pulverized coal particles can be 70 mesh, 75 mesh, 80 mesh, 85 mesh, 90 mesh, 95 mesh, 100 mesh, etc. By controlling the particle size of the pulverized coal particles to an appropriate size, subsequent pickling and carbonization treatments are facilitated.

[0042] According to some embodiments of the present invention, in step (1), the pulverized coal particles are subjected to an acid wash treatment, including: using hydrochloric acid to carry out an acid wash treatment on the pulverized coal particles, wherein the concentration of the hydrochloric acid is 2%-10%. For example, the concentration of the hydrochloric acid in the acid wash treatment can be 2%, 3%, 4%, 5%, 6%, 7%, 8%, 9%, 10%, etc. If the concentration of the hydrochloric acid is too high, it will cause corrosion damage to the pulverized coal particles; if the concentration of the hydrochloric acid is too low, it will not have a good effect of removing impurities. By using hydrochloric acid to carry out an acid wash treatment on the pulverized coal particles and adjusting the concentration of the hydrochloric acid to be 2%-10%, impurities such as ash in the pulverized coal particles can be removed.

[0043] According to some embodiments of the present invention, in step (1), the pulverized coal particles are subjected to an acid wash treatment, including stirring and oscillating during the acid wash treatment, and the acid wash treatment time is not less than 1 hour. For example, the acid wash treatment time can be 1 hour, 1.2 hours, 1.3 hours, 1.4 hours, 1.5 hours, etc. If the acid wash treatment time is too short, it will not achieve a good effect of removing impurities. By using hydrochloric acid to carry out an acid wash treatment on the pulverized coal particles accompanied by stirring and oscillating, and ensuring that the acid wash treatment time is not less than 1 hour, it can fully achieve the effect of removing impurities such as ash in the pulverized coal particles.

[0044] According to some embodiments of the present invention, in step (2), the mass ratio of coal powder particles to potassium hydroxide is 1:3-4, and the acid-washed coal powder particles are mixed with potassium hydroxide by ball milling or solution impregnation. For example, the mass ratio of coal powder particles to potassium hydroxide can be 1:4, 2:4, 3:4, 5:8, 3:8, etc. By selecting an appropriate mass ratio of coal powder particles to potassium hydroxide and thoroughly mixing them, potassium hydroxide can be used as an activator to improve the adsorption capacity of activated carbon.

[0045] According to some embodiments of the present invention, in step (2), the mixture is carbonized under a nitrogen atmosphere, including: a carbonization temperature of 400-450°C and a carbonization time of 1-1.5 hours. For example, the carbonization temperature can be 400°C, 410°C, 420°C, 430°C, 440°C, 450°C, etc. If the carbonization temperature is too high, the coal powder particles will be pyrolyzed prematurely and gradient heating cannot be formed; if the carbonization temperature is too low, it will be difficult to carbonize the coal powder particles. The carbonization time can be 1 hour, 1.2 hours, 1.3 hours, 1.4 hours, 1.5 hours, etc. If the carbonization time is too long, it is easy to cause the microporous structure of the activated carbon to collapse, reducing the specific surface area and adsorption capacity; if the carbonization time is too short, it is difficult to carbonize the coal powder particles. By carbonizing the mixture of coal powder particles and potassium hydroxide at a temperature of 400-450°C for 1-1.5 hours, the coal powder can be fully carbonized, which facilitates the subsequent pyrolysis activation.

[0046] According to some embodiments of the present invention, in step (2), pyrolysis activation includes: pyrolysis activation under a nitrogen atmosphere, the pyrolysis activation temperature is 750-850°C, and the pyrolysis activation time is 1h-1.5h. For example, the pyrolysis activation temperature can be 750°C, 770°C, 790°C, 810°C, 830°C, 850°C, etc., and the pyrolysis activation time can be 1h, 1.2h, 1.3h, 1.4h, 1.5h, etc. If the pyrolysis temperature is too high or the pyrolysis activation time is too long, the microporous structure of the activated carbon will collapse, reducing the specific surface area and adsorption capacity; if the carbonization temperature is too low or the pyrolysis activation time is too short, it will be difficult to pyrolyze the coal powder particles.

[0047] According to some embodiments of the present invention, in step (4), the pressure of the vacuum impregnation chamber after the vacuum treatment is ≤1.5 bar. For example, the pressure of the vacuum impregnation chamber after the vacuum treatment can be 1.5 bar, 1.4 bar, 1.3 bar, 1.2 bar, 1.1 bar, 1 bar, etc. The vacuum treatment reduces the pressure of the chamber, which can make the vacuum impregnation chamber closer to a vacuum effect. The vacuum environment can promote the penetration of the impregnation solution into the microstructure of the activated carbon, facilitating the subsequent vacuum impregnation treatment of the potassium carbonate / sodium carbonate solution.

[0048] According to some embodiments of the present invention, the molar concentration of the potassium carbonate / sodium carbonate solution is 0.2 mol / L. If the molar concentration of the potassium carbonate / sodium carbonate solution is too high, it is difficult to control the uniformity of the potassium carbonate / sodium carbonate loaded on the sulfur-doped activated carbon; if the molar concentration of the potassium carbonate / sodium carbonate solution is too low, insufficient potassium carbonate / sodium carbonate loaded on the sulfur-doped activated carbon may result. By adjusting the molar concentration of the potassium carbonate / sodium carbonate solution to a moderate 0.2 mol / L, the uniformity of the potassium carbonate / sodium carbonate loading on the sulfur-doped activated carbon is facilitated.

[0049] According to some embodiments of the present invention, in step (4), the median size of the droplets formed after the impregnation solution is atomized is 2-5 μm, which can be adjusted to 1-8 μm by a controller according to the viscosity of the liquid. For example, the median size of the droplets formed after atomization can be 2 μm, 3 μm, 4 μm, 5 μm, etc., which can be adjusted to 1 μm, 2 μm, 3 μm, 4 μm, 5 μm, 6 μm, 7 μm, 8 μm, etc. according to the viscosity of the liquid. By adjusting the appropriate droplet size and liquid viscosity, the loading process of vacuum impregnation can be made more controllable, and the uniformity of potassium carbonate / sodium carbonate loading on sulfur-doped activated carbon can be improved.

[0050] According to some embodiments of the present invention, in step (5), the drying temperature is 100° C., the drying time is 1 hour, and nitrogen is continuously introduced during the drying process. By drying the activated carbon under a nitrogen atmosphere, oxidation of the activated carbon during the high-temperature drying process is avoided, thereby improving the drying efficiency of the activated carbon.

[0051] According to some embodiments of the present invention, the components of coal-fired flue gas include nitrogen, carbon dioxide, water vapor, and oxygen, wherein the volume fraction of nitrogen is 68-75%, the volume fraction of carbon dioxide is 12-15%, the volume fraction of water vapor is 0-10%, and the volume fraction of oxygen is 3-5%. For example, the volume fraction of nitrogen in the coal-fired flue gas can be 68%, 69%, 70%, 71%, 72%, 73%, 74%, 75%, etc.; the volume fraction of carbon dioxide in the coal-fired flue gas can be 12%, 13%, 14%, 15%, etc.; the volume fraction of water vapor in the coal-fired flue gas can be 0%, 1%, 2%, 3%, 4%, 5%, 6%, 7%, 8%, 9%, 10%, etc.; and the volume fraction of oxygen in the coal-fired flue gas can be 3%, 3.5%, 4%, 4.5%, 5%, etc. The CO2 in the coal-fired flue gas is captured by using potassium carbonate / sodium carbonate loaded with sulfur self-doped activated carbon, so that the potassium carbonate / sodium carbonate reacts chemically with water vapor and CO2 to absorb a part of the CO2, and then the adsorption capacity of the activated carbon is used to absorb the remaining CO2, thereby achieving the purpose of removing CO2 from the coal-fired flue gas.

[0052] According to the second embodiment of the present invention, the potassium carbonate / sodium carbonate loaded-sulfur self-doping activated carbon for capturing CO2 from coal-fired flue gas is prepared by the preparation method of the potassium carbonate / sodium carbonate loaded-sulfur self-doping activated carbon for capturing CO2 from coal-fired flue gas according to the first embodiment of the present invention.

[0053] According to the potassium carbonate / sodium carbonate loaded-sulfur self-doped activated carbon for capturing CO2 from coal-fired flue gas according to the embodiment of the present invention, high-sulfur coal is selected as the raw material of the activated carbon. Without introducing an external sulfur source, the sulfur element of the high-sulfur coal is used for doping and modification, thereby reducing the preparation cost. The formation of chemical bonds between the sulfur element and the surface of the activated carbon is conducive to the formation of a multi-level pore structure of the activated carbon, thereby enhancing the adsorption selectivity and adsorption capacity of the activated carbon. The activated carbon loaded with potassium carbonate / sodium carbonate has a multi-level CO2 adsorption capacity with the coexistence of chemical adsorption of the outer mesopores and physical adsorption of the inner micropores, which can reduce the adverse effects of water vapor on the CO2 physical adsorption process.

[0054] Throughout this specification, reference to terms such as "one embodiment," "some embodiments," "illustrative embodiments," "examples," "specific examples," or "some examples" means that a specific feature, structure, material, or characteristic described in conjunction with that embodiment or example is included in at least one embodiment or example of the present invention. In this specification, illustrative uses 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 any one or more embodiments or examples.

[0055] While embodiments of the present invention have been shown and described, it will be appreciated by those skilled in the art that various changes, modifications, substitutions, and variations may be made to the embodiments without departing from the principles and spirit of the invention, and that the scope of the invention is defined by the claims and their equivalents.

Claims

1. A method for preparing potassium carbonate / sodium carbonate loaded-sulfur self-doped activated carbon for CO2 capture from coal-fired flue gas, characterized in that: include: Step (1), crushing and screening the high-sulfur coal to form coal powder particles, and performing acid washing on the coal powder particles; Step (2), mixing the acid-washed pulverized coal particles with potassium hydroxide to form a mixture, carbonizing the mixture under a nitrogen atmosphere, and then pyrolyzing and activating the mixture to form crude activated carbon; Step (3), ultrasonically cleaning and drying the crude activated carbon to obtain sulfur-doped activated carbon; Step (4), placing the sulfur-doped activated carbon in a vacuum impregnation device, evacuating the vacuum impregnation chamber where the sulfur-doped activated carbon is located to form a negative pressure environment, and atomizing the impregnation solution and passing it into the vacuum impregnation chamber, wherein the impregnation solution is a potassium carbonate / sodium carbonate solution; Step (5), drying the impregnated sulfur-doped activated carbon to obtain the potassium carbonate / sodium carbonate-loaded sulfur self-doped activated carbon.

2. The method for preparing potassium carbonate / sodium carbonate loaded-sulfur self-doped activated carbon for CO2 capture from coal-fired flue gas according to claim 1, characterized in that: In step (1), the particle size of the coal powder particles is 70-100 mesh.

3. The method for preparing potassium carbonate / sodium carbonate loaded-sulfur self-doped activated carbon for CO2 capture from coal-fired flue gas according to claim 1, characterized in that: In step (1), the pulverized coal particles are subjected to an acid wash treatment, comprising: using hydrochloric acid to carry out an acid wash treatment on the pulverized coal particles, wherein the concentration of the hydrochloric acid is 2%-10%; And / or, in step (1), the pulverized coal particles are subjected to an acid wash treatment, including: stirring and shaking during the acid wash treatment, and the acid wash treatment time is not less than 1 hour.

4. The method for preparing potassium carbonate / sodium carbonate loaded-sulfur self-doped activated carbon for CO2 capture from coal-fired flue gas according to claim 1, characterized in that: In step (2), the mass ratio of the coal powder particles to potassium hydroxide is 1:3-4, and the acid-washed coal powder particles are mixed and doped with potassium hydroxide by ball milling or solution impregnation.

5. The method for preparing potassium carbonate / sodium carbonate loaded-sulfur self-doped activated carbon for CO2 capture from coal-fired flue gas according to claim 1, characterized in that: In step (2), the mixture is carbonized under a nitrogen atmosphere, comprising: a carbonization temperature of 400-450° C., and a carbonization time of 1-1.5 h; In step (2), the pyrolysis activation includes: performing pyrolysis activation under a nitrogen atmosphere, the pyrolysis activation temperature is 750-850° C., and the pyrolysis activation time is 1 h to 1.5 h.

6. The method for preparing potassium carbonate / sodium carbonate loaded-sulfur self-doped activated carbon for CO2 capture from coal-fired flue gas according to claim 1, characterized in that: In step (4), the vacuum impregnation chamber is subjected to a vacuum treatment so that the chamber pressure is ≤1.5 bar; And / or, the molar concentration of the potassium carbonate / sodium carbonate solution is 0.2 mol / L.

7. The method for preparing potassium carbonate / sodium carbonate loaded-sulfur self-doped activated carbon for CO2 capture from coal-fired flue gas according to claim 1, characterized in that: In step (4), the median size of the droplets formed by the atomization of the impregnation solution is 2-5 μm, which can be adjusted to 1-8 μm by a controller according to the viscosity of the liquid.

8. The method for preparing potassium carbonate / sodium carbonate loaded-sulfur self-doped activated carbon for CO2 capture from coal-fired flue gas according to claim 1, characterized in that: In step (5), the drying temperature is 100° C., the drying time is 1 h, and nitrogen is continuously introduced during the drying process.

9. The method for preparing potassium carbonate / sodium carbonate loaded sulfur self-doped activated carbon for CO2 capture from coal-fired flue gas according to any one of claims 1 to 8, characterized in that: The components of the coal-fired flue gas include nitrogen, carbon dioxide, water vapor and oxygen, wherein the volume fraction of nitrogen is 68-75%, the volume fraction of carbon dioxide is 12-15%, the volume fraction of water vapor is 0-10%, and the volume fraction of oxygen is 3-5%.

10. A potassium carbonate / sodium carbonate loaded-sulfur self-doped activated carbon for CO2 capture from coal-fired flue gas, characterized in that: The potassium carbonate / sodium carbonate loaded-sulfur self-doping activated carbon is prepared by the preparation method of potassium carbonate / sodium carbonate loaded-sulfur self-doping activated carbon for capturing CO2 from coal-fired flue gas according to any one of claims 1 to 9.

Images