Preparation method of spherical calcium-based carbon dioxide adsorbent and adsorbent

Abstract

The invention relates to a spherical calcium-based carbon dioxide adsorbent preparation method and an adsorbent, and the preparation method comprises the following steps: dissolving a calcium precursor and an organic acid in a solvent according to a preset proportion to prepare a precursor solution; the precursor solution is atomized into spray by means of atomized gas, and the volume flow ratio of the atomized gas to the precursor solution is 1000-4000, preferably 1500-3000; enabling the spray to enter a high-temperature area of a high-temperature heating through cavity, and controlling the temperature of the high-temperature area to be within a preset pyrolysis temperature, so that the spray is pyrolyzed and a pyrolysis product is formed; the pyrolysis product is collected and transferred to a high-temperature heating furnace in a preset environment to be calcined, and the spherical calcium-based carbon dioxide adsorbent is generated and has the advantage that the performance of the adsorbent is improved.

Description

Technical Field

[0001] This invention relates to the technical field of carbon dioxide capture, and in particular to a method for preparing a spherical calcium-based carbon dioxide adsorbent and the adsorbent itself. Background Technology

[0002] Carbon dioxide capture and utilization (CCUS) technology is a strategic reserve technology for achieving large-scale, low-carbon utilization of fossil fuels. Among these technologies, calcium-cycle solid carbon dioxide adsorption technology falls under the post-combustion carbon dioxide capture field of CCUS. It can capture carbon dioxide from exhaust gases emitted by thermal power plants, cement plants, and steel plants without affecting existing industrial production operations. Compared to existing organic amine solution absorption technology, it offers advantages such as a wide range of adsorbent sources, low cost, high adsorption capacity, non-toxicity, non-corrosiveness, and no secondary pollution, making it highly promising for large-scale application.

[0003] The calcium cycle technology utilizes the reversible reaction between calcium oxide and carbon dioxide to achieve efficient capture of carbon dioxide and regeneration of adsorbent in industrial flue gas: Through the carbonation reaction CaO(s) + CO2(g) → CaCO3(s) at 600-700℃, low-concentration carbon dioxide in the flue gas can be converted into calcium carbonate, thereby obtaining clean flue gas that can be emitted into the atmosphere; then, through the calcination decomposition reaction CaCO3(s) → CaO(s) + CO2(g) at 850-950℃, the calcium oxide adsorbent can be regenerated and high-concentration carbon dioxide that can be compressed, stored, and utilized can be obtained.

[0004] However, calcium-based adsorbents are prone to sintering during cyclic high-temperature calcination, leading to grain growth, pore collapse and blockage, and a decrease in specific surface area, causing their carbon dioxide adsorption capacity to rapidly decline with increasing cycle number.

[0005] To obtain high-performance calcium-based adsorbents, microstructure optimization and modification is currently a mainstream research goal in academia. Examples include synthesizing calcium nanocrystals and generating porous hollow spherical structures, which can effectively improve the carbonation reaction rate and cyclic carbon dioxide adsorption capacity of calcium-based adsorbents. Currently, existing methods for modifying calcium-based adsorbents mainly include the sol-gel method, template method, and ultrasonic spray pyrolysis method; however, all of these methods face difficulties in large-scale application. For example: The sol-gel method is one of the mainstream methods used in academia to modify calcium-based adsorbents. This method involves hydrolyzing, condensing, and drying a solution containing a metal precursor / oxidant (mostly nitrates) and a complexing agent / fuel to form a sol and gel. During heat treatment, these react with a redox reaction, releasing a large amount of gas. After further heat treatment, including combustion and high-temperature calcination, nanoparticles with high specific surface area and abundant pore structure are obtained. While this method can effectively improve the carbon dioxide capture performance of calcium-based adsorbents, the self-propagating nature of gel combustion makes it difficult to effectively control the microstructure of the calcium-based adsorbent. Furthermore, the complex preparation process, typically taking more than 24 hours, makes continuous production difficult.

[0006] In contrast, the template method can prepare products with specific structures and sizes by adding and removing template agents (such as carbon microspheres and polystyrene microspheres), thereby achieving precise control over the microstructure and particle size distribution of calcium-based adsorbents. However, the template agents used in this method usually need to be prepared by hydrothermal synthesis under harsh conditions of high temperature, high pressure, and long duration, and the deposition process of metal ions on the template surface during synthesis requires at least 6-10 hours. Therefore, it also faces many challenges in large-scale production.

[0007] Compared to the two modification methods mentioned above, the ultrasonic spray pyrolysis method combines good control over the product's microstructure with high potential for large-scale application, ensuring a rapid, continuous, and controllable synthesis process. This method uses an ultrasonic atomizing device to atomize the precursor solution and deliver it to a high-temperature zone, where solvent evaporation, solute precipitation, and thermal decomposition occur, ultimately transforming it into micron- to nano-sized solid particles. Furthermore, by adjusting the preparation conditions, particles with various structures such as hollow spheres, solid spheres, and discs can be obtained. However, this synthesis method typically uses an ultrasonic atomizing generator as the atomizing device, which utilizes ultrasonic waves generated by the high-frequency vibration of a piezoelectric crystal to disperse the liquid into tiny droplets. Although this method can produce ultrafine droplets with a particle size of 1-20 μm and uniform distribution, it has significant limitations, such as: (1) Narrow applicability of liquids: Ultrasonic atomizers can atomize solutions with viscosity close to that of water, but cannot handle high-viscosity liquids, which greatly limits the selection of precursor solutions in spray pyrolysis technology; (2) Narrow adjustable range: Ultrasonic atomizers can adjust the atomization effect within a small range by changing the vibration frequency of the piezoelectric crystal, but their ability to control the particle size is limited when applied to spray pyrolysis.

[0008] (3) Low yield: The atomization rate of ultrasonic atomization equipment is usually less than 1 cm. 3 The atomization rate is approximately 0.1-1 mL / s, which limits its application in large-scale powder production using spray pyrolysis. (4) Ultrasonic atomization equipment has a complex structure, high cost, high failure rate and short service life. Summary of the Invention

[0009] The technical problem to be solved by the present invention is to overcome the defects in the prior art, thereby providing a method for preparing spherical calcium-based carbon dioxide adsorbent and the adsorbent itself.

[0010] To achieve the above objectives, the present invention adopts the following technical solution: A method for preparing a spherical calcium-based carbon dioxide adsorbent includes: The calcium precursor and organic acid are dissolved in a solvent in a predetermined ratio to prepare a precursor solution. The precursor solution is atomized into a spray using an atomizing gas, wherein the volumetric flow rate ratio of the atomizing gas to the precursor solution is 1000-4000, preferably 1500-3000. The spray is directed into the high-temperature region of the high-temperature heating through-cavity, and the temperature of the high-temperature region is controlled within a preset pyrolysis temperature so that the spray undergoes pyrolysis and forms pyrolysis products. The pyrolysis products are collected and transferred to a high-temperature heating furnace in a predetermined environment for calcination to generate spherical calcium-based carbon dioxide adsorbent.

[0011] Preferably, the calcium ion concentration in the precursor solution is in the range of 0.1-2.5 mol / L, more preferably 0.5-2 mol / L.

[0012] Preferably, the molar ratio of organic acid to calcium ions in the precursor solution is 0.5:1-2:1, more preferably 0.75:1-1.25:1.

[0013] Preferably, the calcium precursor is configured as one or a combination of calcium nitrate, calcium chloride, calcium acetate, and calcium citrate; And / or, The organic acid is set as one or a combination of citric acid, formic acid, acetic acid, propionic acid, and glycine; And / or, The solvent is set to one or a combination of deionized water and ethanol.

[0014] Preferably, the atomization of the precursor solution into a spray using atomizing gas specifically includes the following steps: The precursor solution is supplied to the dual-fluid nozzle at a preset flow rate, and at the same time, the atomizing gas is supplied to the dual-fluid nozzle at a preset flow rate and preset pressure.

[0015] Preferably, the atomizing gas can be one or a combination of compressed air and nitrogen.

[0016] Preferably, the preset pyrolysis temperature ranges from 450 to 700°C, and more preferably from 550 to 650°C.

[0017] Preferably, the preset environment includes a calcination temperature and a calcination gas atmosphere; the calcination temperature ranges from 700 to 950°C, preferably 800 to 900°C; and the calcination gas atmosphere is an air atmosphere. Preferably, the pyrolysis product is calcined in the high-temperature heating furnace for 5-60 minutes, more preferably 10-30 minutes.

[0018] A spherical calcium-based carbon dioxide adsorbent is prepared using the above-described method for preparing a spherical calcium-based carbon dioxide adsorbent.

[0019] Compared with the prior art, the beneficial effects of the present invention are as follows: The method for preparing spherical calcium-based carbon dioxide adsorbents provided in the above technical solution utilizes the shear force generated by the relative motion between a high-speed airflow and the solution to break the solution into tiny droplets. By rationally setting the volumetric flow rates of the atomizing gas and the precursor solution, a wide adjustment range is possible, and fine-tuning can be performed for solutions of different viscosities to more accurately control droplet size, improve spray uniformity, and ensure the quality stability of subsequent pyrolysis and calcination processes. Furthermore, it enables controllable, continuous, and rapid production of spherical calcium-based carbon dioxide adsorbents, improving production efficiency to a certain extent compared to traditional modification methods. In addition, this preparation method employs equipment such as a dual-fluid nozzle, a high-temperature heating through-cavity (e.g., a tube furnace), and a high-temperature heating furnace (e.g., a muffle furnace), resulting in a simpler equipment structure. Attached Figure Description

[0020] To more clearly illustrate the specific embodiments of the present invention or the technical solutions in the prior art, the drawings used in the description of the specific embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are some embodiments of the present invention. For those skilled in the art, other drawings can be obtained from these drawings without creative effort.

[0021] Figure 1 SEM image and schematic diagram of particle size statistics of calcium-based carbon dioxide adsorbent (sample 1) prepared according to Example 1 of the present invention.

[0022] Figure 2 A schematic diagram showing the test results of the cyclic carbon dioxide capture performance of the calcium-based carbon dioxide adsorbent (sample 1) prepared according to Example 1 of the present invention.

[0023] Figure 3SEM image and schematic diagram of particle size statistics of calcium-based carbon dioxide adsorbent (sample 2) prepared in Example 2 of the present invention.

[0024] Figure 4 A schematic diagram showing the test results of the cyclic carbon dioxide capture performance of the calcium-based carbon dioxide adsorbent (sample 2) prepared in Example 2 of the present invention.

[0025] Figure 5 SEM image and schematic diagram of particle size statistics of calcium-based carbon dioxide adsorbent (sample 3) prepared in Example 3 of the present invention.

[0026] Figure 6 A schematic diagram showing the test results of the cyclic carbon dioxide capture performance of the calcium-based carbon dioxide adsorbent (sample 3) prepared in Example 3 of the present invention.

[0027] Figure 7 SEM image and schematic diagram of particle size statistics of calcium-based carbon dioxide adsorbent (sample 4) prepared in Example 4 of this invention.

[0028] Figure 8 A schematic diagram showing the test results of the cyclic carbon dioxide capture performance of the calcium-based carbon dioxide adsorbent (sample 4) prepared in Example 4 of the present invention.

[0029] Figure 9 SEM image and schematic diagram of particle size statistics of calcium-based carbon dioxide adsorbent (sample 5) prepared in Example 5 of the present invention.

[0030] Figure 10 A schematic diagram showing the test results of the cyclic carbon dioxide capture performance of the calcium-based carbon dioxide adsorbent (sample 5) prepared in Example 5 of the present invention.

[0031] Figure 11 SEM image and schematic diagram of particle size statistics of the calcium-based carbon dioxide adsorbent (sample 6) prepared in Example 6 of this invention.

[0032] Figure 12 A schematic diagram showing the test results of the cyclic carbon dioxide capture performance of the calcium-based carbon dioxide adsorbent (sample 6) prepared in Example 6 of this invention.

[0033] Figure 13 SEM image and schematic diagram of particle size statistics of calcium-based carbon dioxide adsorbent (sample 7) prepared in Example 7 of this invention.

[0034] Figure 14 A schematic diagram showing the test results of the cyclic carbon dioxide capture performance of the calcium-based carbon dioxide adsorbent (sample 7) prepared in Example 7 of the present invention.

[0035] Figure 15 SEM image and particle size statistics of the calcium-based carbon dioxide adsorbent (sample 8) prepared for comparative example one of the present invention.

[0036] Figure 16 A schematic diagram showing the test results of the circulating carbon dioxide capture performance of the calcium-based carbon dioxide adsorbent (sample 8) prepared for comparative example one of the present invention.

[0037] Figure 17 SEM image and schematic diagram of particle size statistics of the calcium-based carbon dioxide adsorbent (sample 9) prepared for comparative example 2 provided by the present invention.

[0038] Figure 18 A schematic diagram showing the test results of the circulating carbon dioxide capture performance of the calcium-based carbon dioxide adsorbent (sample 9) prepared in Comparative Example 2 provided by the present invention.

[0039] Figure 19 SEM image and particle size statistics of the calcium-based carbon dioxide adsorbent (sample 10) prepared for Comparative Example 3 provided by the present invention.

[0040] Figure 20 A schematic diagram showing the test results of the circulating carbon dioxide capture performance of the calcium-based carbon dioxide adsorbent (sample 10) prepared in Comparative Example 3 provided by the present invention.

[0041] Figure 21 SEM image and schematic diagram of particle size statistics of the calcium-based carbon dioxide adsorbent (sample 11) prepared for Comparative Example 4 provided by the present invention.

[0042] Figure 22 A schematic diagram showing the test results of the circulating carbon dioxide capture performance of the calcium-based carbon dioxide adsorbent (sample 11) prepared for Comparative Example 4 provided by the present invention.

[0043] Figure 23 SEM image and schematic diagram of particle size statistics of the calcium-based carbon dioxide adsorbent (sample 12) prepared in Comparative Example 5 provided by the present invention.

[0044] Figure 24 A schematic diagram showing the test results of the circulating carbon dioxide capture performance of the calcium-based carbon dioxide adsorbent (sample 12) prepared in Comparative Example 5 provided by the present invention.

[0045] Figure 25 A schematic diagram showing the test results of the circulating carbon dioxide capture performance of the calcium-based carbon dioxide adsorbent (sample 13) prepared in Comparative Example 6 provided by the present invention. Detailed Implementation

[0046] The technical solution of the present invention will now be clearly and completely described with reference to the accompanying drawings. Obviously, the described embodiments are only some, not all, of the embodiments of the present invention. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0047] In the description of this invention, it should be noted that the terms "center," "upper," "lower," "left," "right," "vertical," "horizontal," "inner," and "outer," etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. They are used only for the convenience of describing the invention and for simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limitations on the invention. Furthermore, the terms "first," "second," and "third" are used for descriptive purposes only and should not be construed as indicating or implying relative importance.

[0048] In the description of this invention, it should be noted that, unless otherwise explicitly specified and limited, the terms "installation," "connection," and "linking" should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral connection; they can refer to a mechanical connection or an electrical connection; they can refer to a direct connection or an indirect connection through an intermediate medium; and they can refer to the internal connection of two components. Those skilled in the art can understand the specific meaning of the above terms in this invention based on the specific circumstances.

[0049] This invention provides a method for preparing a spherical calcium-based carbon dioxide adsorbent, comprising the following steps: S1: Dissolve the calcium precursor and organic acid in a solvent according to a preset ratio to prepare a precursor solution.

[0050] Specifically, in actual operation, a certain amount of calcium precursor and a certain amount of organic acid can be obtained and dissolved in a solvent containing a certain amount of solvent. Then, the dissolved solution is transferred to a 100mL volumetric flask and diluted to a final volume to prepare a precursor solution with preset parameters (such as the concentration of calcium ions in the solution, the molar ratio of organic acid and calcium ions within a preset range).

[0051] Furthermore, the calcium ion concentration in the precursor solution ranges from 0.1 to 2.5 mol / L, preferably from 0.5 to 2 mol / L.

[0052] Furthermore, the molar ratio of organic acid to calcium ions in the precursor solution is 0.5:1-2:1, preferably 0.75:1-1.25:1.

[0053] Furthermore, the calcium precursor is set as one or a combination of calcium nitrate, calcium chloride, calcium acetate, and calcium citrate; the organic acid is set as one or a combination of citric acid, formic acid, acetic acid, propionic acid, and glycine; and the solvent is set as one or a combination of deionized water and ethanol.

[0054] S2: The precursor solution is atomized into a spray using atomizing gas. The volumetric flow rate ratio of the atomizing gas to the precursor solution is 1000-4000, preferably 1500-3000.

[0055] Specifically, in operation, the precursor solution is supplied to the dual-fluid nozzle at a preset flow rate (supply flow rate), and simultaneously, the atomizing gas is supplied to the dual-fluid nozzle at a preset flow rate (supply flow rate) and a preset pressure. Specifically, the delivery device can be a peristaltic pump, syringe pump, etc. The supply flow rates of the precursor solution and the atomizing gas can be reasonably set to ensure that the volumetric flow rate ratio of the atomizing gas to the precursor solution is 1000-4000, preferably 1500-3000. For example, when the supply flow rate of the precursor solution is 10 mL / min, the supply flow rate of the atomizing gas can be set to 20 L / min, that is, the volumetric flow rate ratio of the atomizing gas to the precursor solution is 2000.

[0056] Furthermore, the atomizing gas can be set to one or a combination of compressed air and nitrogen, and the preset pressure of the atomizing gas supply can be set to 0.3 MPa.

[0057] S3: The spray is directed into the high-temperature region of the high-temperature heating through-cavity, and the temperature of the high-temperature region is controlled within a preset pyrolysis temperature so that the spray undergoes pyrolysis and forms pyrolysis products. Specifically, the preset pyrolysis temperature ranges from 450 to 700°C, preferably 550 to 650°C.

[0058] S4: Collect the pyrolysis products and transfer them to a high-temperature heating furnace in a preset environment for calcination to generate spherical calcium-based carbon dioxide adsorbent.

[0059] Specifically, the preset environment includes calcination temperature and calcination gas atmosphere. The calcination temperature ranges from 700 to 950°C, preferably from 800 to 900°C. The calcination gas atmosphere is an air atmosphere.

[0060] Furthermore, the calcination time of the pyrolysis products in the high-temperature heating furnace is 5-60 min, preferably 10-30 min.

[0061] The present invention also provides a spherical calcium-based carbon dioxide adsorbent, which is prepared by the above preparation method.

[0062] To assess the performance of the prepared spherical calcium-based carbon dioxide adsorbent, multiple example groups and comparative groups were set up to obtain different samples. The microstructure of the spherical calcium-based carbon dioxide adsorbent was then characterized using a scanning electron microscope. The circulating carbon dioxide capture performance of the spherical calcium-based carbon dioxide adsorbent was tested using a simultaneous thermal analyzer.

[0063] Specifically, the microstructure of the calcium-based carbon dioxide adsorbent samples was characterized using a NovaNanoSEM450 scanning electron microscope manufactured by FEI (Netherlands) with an accelerating voltage of 15 kV and a current of 3.5 μA. Prior to observation, a thin layer of Au was deposited on the sample surface using a 108Auto ion sputtering system manufactured by Cressington (UK) to enhance conductivity.

[0064] Furthermore, a simultaneous thermal analyzer, the STA2500regulus model manufactured by NETZSCH GmbH in Germany, can be used. For each test, 2-3 mg of sample should be taken in an alumina crucible. The temperature procedure and atmospheric conditions are as follows: First, under a nitrogen atmosphere of 100 mL / min, the temperature is increased from 25°C to 850°C at a rate of 30°C / min and held constant for 3 minutes for pre-calcination. Then, the temperature is decreased to 650°C at a rate of 30°C / min. At this temperature, the atmosphere is switched to carbon dioxide at a rate of 15 mL / min and nitrogen at a rate of 85 mL / min for a 10-minute carbonation test. Subsequently, the atmosphere is switched to nitrogen at a rate of 100 mL / min, and the temperature is increased from 650°C to 950°C at a rate of 30°C / min. After reaching the target temperature, the atmosphere is switched to carbon dioxide at a rate of 80 mL / min and nitrogen at a rate of 20 mL / min and held constant for 3 minutes as the calcination stage. After the calcination stage, the atmosphere was switched to nitrogen at a rate of 100 mL / min, and the temperature was reduced to 650°C at a rate of 30°C / min. This cycle was repeated 30 times. The sample was in the... n The formula for calculating the carbonation conversion rate in the next cycle is: [ M CaO ( m n - m 0)] / ( M CO2 m 0)*100%, where M CaO and M CO2 These are the relative molecular masses of calcium oxide and carbon dioxide, respectively, with values ​​of 56 and 44. m 0 and m nThese are respectively the first cycle of calcination and the second cycle. n Sample quality after secondary carbonation. Sample quality after the first carbonation. n The formula for calculating the CO2 adsorption capacity of the next cycle is: ( m n - m 0) / m 0.

[0065] The following are some specific embodiments and comparative examples provided in this application: Example 1 S1: Weigh 23.615g (0.1mol) calcium nitrate tetrahydrate and 21.014g (0.1mol) citric acid monohydrate and dissolve them in a beaker containing an appropriate amount of deionized water. Then transfer the solution to a 100mL volumetric flask and make up to volume to prepare a precursor solution with a calcium ion concentration of 1mol / L and a molar ratio of organic acid to calcium ions of 1:1.

[0066] S2: A peristaltic pump is used to supply the precursor solution to the two-fluid nozzle at a flow rate of 10 mL / min. Simultaneously, compressed air at a pressure of 0.3 MPa and a flow rate of 20 L / min is supplied to the two-fluid nozzle to form a spray, that is, the volumetric flow rate ratio of atomizing gas to precursor solution is 2000.

[0067] S3: The spray enters the high-temperature heated through-cavity at 600℃ and undergoes pyrolysis.

[0068] S4: Collect the pyrolysis products and calcine them in a high-temperature furnace at 850°C under air atmosphere for 10 minutes to obtain spherical calcium-based carbon dioxide adsorbent, i.e., Sample 1.

[0069] The performance of sample 1 was verified, and the specific results are as follows: See Figure 1 , Figure 1 (a) is the SEM image of sample 1 at 1000x magnification; (b) is the SEM image of sample 1 at 15000x magnification; and (c) is the SEM image of sample 1 at 120000x magnification.

[0070] Depend on Figure 1 It can be seen that the spherical calcium-based carbon dioxide adsorbent of sample 1 has a spherical structure with a certain particle size distribution. Its average particle size is 9.38 μm as measured by microscopic statistical method. The individual microspheres have good sphericity, rich pore structure on the surface, and are hollow inside. The surface of the microspheres is formed by the growth of nanocrystals of about 100-200 nm to form a porous network structure.

[0071] See Figure 2Compared with the performance curve of commercial analytical grade CaO, the spherical calcium-based carbon dioxide adsorbent of Sample 1 showed a significant improvement in cyclic carbonation conversion rate compared with analytical grade CaO. Its initial conversion rate was 92.68%, which was about 100.6% higher than that of analytical grade CaO (46.21%). The conversion rate after 30 cycles was 29.88%, which was about 103.7% higher than that of analytical grade CaO (14.67%). Its cumulative CO2 adsorption capacity after 30 cycles was 11.39 g / g, which was about 132.5% higher than that of analytical grade CaO (4.9 g / g), demonstrating excellent carbon dioxide capture performance.

[0072] Example 2 S1: Weigh 47.23g (0.2mol) calcium nitrate tetrahydrate and 42.028g (0.2mol) citric acid monohydrate and dissolve them in a beaker containing an appropriate amount of deionized water. Then transfer the solution to a 100mL volumetric flask and make up to volume to prepare a precursor solution with a calcium ion concentration of 2mol / L and a molar ratio of organic acid to calcium ions of 1:1.

[0073] S2: A peristaltic pump is used to supply the precursor solution to the two-fluid nozzle at a flow rate of 10 mL / min. Simultaneously, compressed air at a pressure of 0.3 MPa and a flow rate of 20 L / min is supplied to the two-fluid nozzle to form a spray, that is, the volumetric flow rate ratio of atomizing gas to precursor solution is 2000.

[0074] S3: The spray enters the high-temperature heated through-cavity at 600℃ and undergoes pyrolysis.

[0075] S4: Collect the pyrolysis products and calcine them in a high-temperature furnace at 850°C under air atmosphere for 10 minutes to obtain spherical calcium-based carbon dioxide adsorbent, i.e., Sample 2.

[0076] The performance of sample 2 was verified, and the specific results are as follows: See Figure 3 , Figure 3 (a) is the SEM image of sample 2 at 1000x magnification; (b) is the SEM image of sample 2 at 15000x magnification; and (c) is the SEM image of sample 2 at 120000x magnification.

[0077] Depend on Figure 3 It can be seen that the spherical calcium-based carbon dioxide adsorbent of sample 2 exhibits a spherical structure with a certain particle size distribution. Its average particle size was measured to be 11.36 μm by microscopic statistical method. The individual microspheres have good sphericity, rich pore structure on the surface, and are hollow inside. The surface of the microspheres is formed by the growth of nanocrystals of about 100-200 nm to form a porous network structure.

[0078] See Figure 4Compared with the performance curve of commercial analytical grade CaO, the cyclic carbon dioxide adsorbent of Sample 2 showed a significant improvement in cyclic carbonation conversion rate compared with analytical grade CaO. Its initial conversion rate was 90.58%, which was about 96% higher than that of analytical grade CaO (46.21%). The conversion rate after 30 cycles was 20.65%, which was about 40.8% higher than that of analytical grade CaO (14.67%). Its cumulative CO2 adsorption capacity after 30 cycles was 8.98 g / g, which was about 83.2% higher than that of analytical grade CaO (4.9 g / g), showing good carbon dioxide capture performance.

[0079] Example 3 S1: Weigh 23.615g (0.1mol) calcium nitrate tetrahydrate and 10.507g (0.05mol) citric acid monohydrate and dissolve them in a beaker containing an appropriate amount of deionized water. Then transfer the solution to a 100mL volumetric flask and make up to volume to prepare a precursor solution with a calcium ion concentration of 1mol / L and a molar ratio of organic acid to calcium ions of 0.5:1.

[0080] S2: A peristaltic pump is used to supply the precursor solution to the two-fluid nozzle at a flow rate of 10 mL / min. Simultaneously, compressed air at a pressure of 0.3 MPa and a flow rate of 20 L / min is supplied to the two-fluid nozzle to form a spray, i.e., the volumetric flow rate ratio of atomizing gas to precursor solution is 2000.

[0081] S3: The spray enters the high-temperature heated through-cavity at 600℃ and undergoes pyrolysis.

[0082] S4: Collect the pyrolysis products and calcine them in a high-temperature furnace at 850°C under air atmosphere for 10 minutes to obtain spherical calcium-based carbon dioxide adsorbent, namely sample 3.

[0083] The performance of sample 3 was verified, and the specific results are as follows: See Figure 5 , Figure 5 (a) is the SEM image of sample 3 at 1000x magnification; (b) is the SEM image of sample 3 at 15000x magnification; and (c) is the SEM image of sample 3 at 120000x magnification.

[0084] Depend on Figure 5 It can be seen that the spherical calcium-based carbon dioxide adsorbent of sample 3 exhibits a spherical structure with a certain particle size distribution. Its average particle size was measured to be 7.21 μm by microscopic statistical method. The individual microspheres have good sphericity, rich pore structure on the surface, and are hollow inside. The surface of the microspheres is formed by the growth of nanocrystals of about 100-200 nm to form a porous network structure.

[0085] See Figure 6Compared with the performance curve of commercial analytical grade CaO, the cyclic carbon dioxide adsorbent of sample 3 showed a significant improvement in cyclic carbonation conversion rate compared with analytical grade CaO. Its initial conversion rate was 94.61%, which was about 104.7% higher than that of analytical grade CaO (46.21%). The conversion rate after 30 cycles was 19.7%, which was about 34.3% higher than that of analytical grade CaO (14.67%). Its cumulative CO2 adsorption capacity after 30 cycles was 8.44 g / g, which was about 72.2% higher than that of analytical grade CaO (4.9 g / g), showing good carbon dioxide capture performance.

[0086] Example 4 S1: Weigh 23.615g (0.1mol) calcium nitrate tetrahydrate and 21.014g (0.1mol) citric acid monohydrate and dissolve them in a beaker containing an appropriate amount of deionized water. Then transfer the solution to a 100mL volumetric flask and make up to volume to prepare a precursor solution with a calcium ion concentration of 1mol / L and a molar ratio of organic acid to calcium ions of 1:1.

[0087] S2: A peristaltic pump is used to supply the precursor solution to the two-fluid nozzle at a flow rate of 10 mL / min. Simultaneously, compressed air at a pressure of 0.3 MPa and a flow rate of 20 L / min is supplied to the two-fluid nozzle to form a spray, i.e., the volumetric flow rate ratio of atomizing gas to precursor solution is 2000.

[0088] S3: The spray enters the high-temperature heated through-cavity at 500℃ and undergoes pyrolysis.

[0089] S4: Collect the pyrolysis products and calcine them in a high-temperature furnace at 850°C under air atmosphere for 10 minutes to obtain spherical calcium-based carbon dioxide adsorbent, i.e., sample 4.

[0090] The performance of sample 4 was verified, and the specific results are as follows: See Figure 7 , Figure 7 (a) is the SEM image of sample 4 at 1000x magnification; (b) is the SEM image of sample 4 at 15000x magnification; and (c) is the SEM image of sample 4 at 120000x magnification.

[0091] Depend on Figure 7 It can be seen that the spherical calcium-based carbon dioxide adsorbent of sample 4 exhibits a spherical structure with a certain particle size distribution. Its average particle size was measured to be 9.54 μm by microscopic statistical method. The individual microspheres have good sphericity, rich pore structure on the surface, and are hollow inside. The surface of the microspheres is formed by the growth of nanocrystals of about 100-200 nm to form a porous network structure.

[0092] See Figure 8Compared with the performance curve of commercial analytical grade CaO, the cyclic carbon dioxide adsorbent of sample 4 showed a significant improvement in cyclic carbonation conversion rate compared with analytical grade CaO. Its initial conversion rate was 95.46%, which was about 106.6% higher than that of analytical grade CaO (46.21%). The conversion rate after 30 cycles was 19.7%, which was about 34.3% higher than that of analytical grade CaO (14.67%). Its cumulative CO2 adsorption capacity after 30 cycles was 8.77 g / g, which was about 79.1% higher than that of analytical grade CaO (4.9 g / g), showing good carbon dioxide capture performance.

[0093] Example 5 S1: Weigh 23.615g (0.1mol) calcium nitrate tetrahydrate and 21.014g (0.1mol) citric acid monohydrate and dissolve them in a beaker containing an appropriate amount of deionized water. Then transfer the solution to a 100mL volumetric flask and make up to volume to prepare a precursor solution with a calcium ion concentration of 1mol / L and a molar ratio of organic acid to calcium ions of 1:1.

[0094] S2: A peristaltic pump is used to supply the precursor solution to the two-fluid nozzle at a flow rate of 10 mL / min. Simultaneously, compressed air at a pressure of 0.3 MPa and a flow rate of 30 L / min is supplied to the two-fluid nozzle to form a spray, i.e., the volumetric flow rate ratio of atomizing gas to precursor solution is 3000.

[0095] S3: The spray enters the high-temperature heated through-cavity at 600℃ and undergoes pyrolysis.

[0096] S4: Collect the pyrolysis products and calcine them in a high-temperature furnace at 850°C under air atmosphere for 10 minutes to obtain spherical calcium-based carbon dioxide adsorbent, i.e., sample 5.

[0097] The performance of sample 5 was verified, and the specific results are as follows: See Figure 9 , Figure 9 (a) is the SEM image of sample 5 at 1000x magnification; (b) is the SEM image of sample 5 at 15000x magnification; and (c) is the SEM image of sample 5 at 120000x magnification.

[0098] Depend on Figure 9 It can be seen that the spherical calcium-based carbon dioxide adsorbent of sample 5 exhibits a spherical structure with a certain particle size distribution. Its average particle size was measured to be 7.33 μm by microscopic statistical method. The individual microspheres have good sphericity, rich pore structure on the surface, and are hollow inside. The surface of the microspheres is formed by the growth of nanocrystals of about 100-200 nm to form a porous network structure.

[0099] See Figure 10Compared with the performance curve of commercial analytical grade CaO, the cyclic carbon dioxide adsorbent of sample 5 showed a significant improvement in carbonation conversion rate compared with analytical grade CaO. Its initial conversion rate was 91.04%, which was about 97% higher than that of analytical grade CaO (46.21%). The conversion rate after 30 cycles was 23.42%, which was about 59.7% higher than that of analytical grade CaO (14.67%). Its cumulative CO2 adsorption capacity after 30 cycles was 10.16 g / g, which was about 107.4% higher than that of analytical grade CaO (4.9 g / g), showing good carbon dioxide capture performance.

[0100] Example 6 S1: Weigh 9.446 g (0.04 mol) calcium nitrate tetrahydrate and 13.449 g (0.064 mol) citric acid monohydrate and dissolve them in a beaker containing 40 mL of anhydrous ethanol. Then transfer the solution to a 100 mL volumetric flask and make up to volume with deionized water to prepare a precursor solution with a calcium ion concentration of 0.4 mol / L and a molar ratio of organic acid to calcium ions of 1.6:1.

[0101] S2: A peristaltic pump is used to supply the precursor solution to the two-fluid nozzle at a flow rate of 10 mL / min. Simultaneously, nitrogen gas at a pressure of 0.3 MPa and a flow rate of 31 L / min is supplied to the two-fluid nozzle to form a spray, that is, the volume flow rate ratio of atomizing gas to precursor solution is 3:100.

[0102] S3: The spray enters the high-temperature heating cavity at 680℃ and undergoes pyrolysis.

[0103] S4: Collect the pyrolysis products and calcine them in a high-temperature furnace at 750°C under air atmosphere for 40 minutes to obtain spherical calcium-based carbon dioxide adsorbent, namely sample 6.

[0104] The performance of sample 6 was verified, and the specific results are as follows: See Figure 11 , Figure 11 (a) is the SEM image of sample 6 at 1000x magnification; (b) is the SEM image of sample 6 at 15000x magnification; and (c) is the SEM image of sample 6 at 120000x magnification.

[0105] Depend on Figure 11 It can be seen that the spherical calcium-based carbon dioxide adsorbent of sample 6 exhibits a spherical structure with a certain particle size distribution. Its average particle size was measured to be 7.21 μm by microscopic statistical method. The individual microspheres have good sphericity, rich pore structure on the surface, and are hollow inside. The surface of the microspheres is formed by the growth of nanocrystals of about 100-200 nm to form a network structure.

[0106] See Figure 12 Compared with the performance curve of commercial analytical grade CaO, the cyclic carbon dioxide adsorbent of sample 6 showed a significant improvement in cyclic carbonation conversion rate compared with analytical grade CaO. Its initial conversion rate was 91.31%, which was about 97.6% higher than that of analytical grade CaO (46.21%). The conversion rate after 30 cycles was 18.7%, which was about 27.5% higher than that of analytical grade CaO (14.67%). Its cumulative CO2 adsorption capacity after 30 cycles was 8 g / g, which was about 63.3% higher than that of analytical grade CaO (4.9 g / g), showing good carbon dioxide capture performance.

[0107] Example 7 S1: Weigh 11.808 g (0.05 mol) calcium nitrate tetrahydrate, 9.81 g (0.05 mol) calcium acetate monohydrate, 10.507 g (0.05 mol) citric acid monohydrate, and 7.507 g (0.05 mol) glycine and dissolve them in a beaker containing an appropriate amount of deionized water. Then transfer the solution to a 100 mL volumetric flask and make up to volume to prepare a precursor solution with a calcium ion concentration of 1 mol / L and a molar ratio of organic acid to calcium ions of 1:1.

[0108] S2: A peristaltic pump is used to supply the precursor solution to the two-fluid nozzle at a flow rate of 10 mL / min. Simultaneously, compressed air at a pressure of 0.3 MPa and a flow rate of 20 L / min is supplied to the two-fluid nozzle to form a spray, i.e., the volumetric flow rate ratio of atomizing gas to precursor solution is 2000.

[0109] S3: The spray enters the high-temperature heating cavity at 500℃ and undergoes pyrolysis.

[0110] S4: Collect the pyrolysis products and calcine them in a high-temperature furnace at 800°C under air atmosphere for 10 minutes to obtain spherical calcium-based carbon dioxide adsorbent, i.e., sample 7.

[0111] The performance of sample 7 was verified, and the specific results are as follows: See Figure 13 , Figure 13 (a) is the SEM image of sample 7 at 1000x magnification; (b) is the SEM image of sample 7 at 15000x magnification; and (c) is the SEM image of sample 7 at 120000x magnification.

[0112] Depend on Figure 13 It can be seen that the spherical calcium-based carbon dioxide adsorbent of sample 7 exhibits a spherical structure with a certain particle size distribution. Its average particle size was measured to be 11.42 μm by microscopic statistical method. The individual microspheres have good sphericity, and the surface has a relatively rich pore structure. The interior is hollow, and the surface of the microspheres is formed by the growth of nanocrystals of about 100-200 nm to form a network structure.

[0113] See Figure 14 Compared with the performance curve of commercial analytical grade CaO, the spherical calcium-based carbon dioxide adsorbent of sample 7 had a conversion rate of 91.83% in the first cycle, which was about 98.7% higher than that of analytical grade CaO (46.21%). Subsequently, its conversion rate gradually decreased. At the 30th cycle, the conversion rate of the sample was 24.5%, which was 67% higher than that of analytical grade CaO (14.67%). Its cumulative CO2 adsorption capacity after 30 cycles was 8.75 g / g, which was about 78.6% higher than that of analytical grade CaO (4.9 g / g), showing good carbon dioxide capture performance.

[0114] Comparative Example 1 S1: Weigh 70.845 g (0.3 mol) calcium nitrate tetrahydrate and 63.042 g (0.3 mol) citric acid monohydrate and dissolve them in a beaker containing an appropriate amount of deionized water. Then transfer the solution to a 100 mL volumetric flask and make up to volume to prepare a precursor solution with a calcium ion concentration of 3 mol / L and a molar ratio of organic acid to calcium ions of 1:1. It is worth noting that when the calcium ion concentration exceeds 3 mol / L, it cannot be completely dissolved and is not suitable for preparing sprays.

[0115] S2: A peristaltic pump is used to supply the precursor solution to the two-fluid nozzle at a flow rate of 10 mL / min. Simultaneously, compressed air at a pressure of 0.3 MPa and a flow rate of 20 L / min is supplied to the two-fluid nozzle to form a spray, i.e., the volumetric flow rate ratio of atomizing gas to precursor solution is 2000.

[0116] S3: The spray enters the high-temperature heated through-cavity at 600 ℃ and undergoes pyrolysis.

[0117] S4: Collect the pyrolysis products and calcine them in a high-temperature furnace at 850 °C under air atmosphere for 10 min to obtain calcium-based carbon dioxide adsorbent, i.e., sample 8.

[0118] The performance of sample 8 was verified, and the specific results are as follows: See Figure 15 , Figure 15 (a) is the SEM image of sample 8 at 1000x magnification; (b) is the SEM image of sample 8 at 15000x magnification; and (c) is the SEM image of sample 8 at 120000x magnification.

[0119] Depend on Figure 15 It can be seen that the monomer particles of the calcium-based carbon dioxide adsorbent in sample 8 are relatively large, exhibiting irregular hollow spherical structures or cracked and broken spherical shells and fragments, and the monomer surface is formed by the growth and connection of nanocrystals to form a dense structure.

[0120] See Figure 16 Compared with the performance curve of commercial analytical grade CaO, the conversion rate of the spherical calcium-based carbon dioxide adsorbent of sample 8 was 75.69% in the first cycle, which was about 63.8% higher than that of analytical grade CaO (46.21%). Subsequently, its conversion rate dropped rapidly, and the conversion rate of the sample was 16.75% in the 30th cycle, which was only 14.2% higher than that of analytical grade CaO (14.67%). Its cumulative CO2 adsorption capacity after 30 cycles was 6.91 g / g, which was only about 41% higher than that of analytical grade CaO (4.9 g / g).

[0121] Comparative Example 2 S1: Weigh 23.615g (0.1mol) calcium nitrate tetrahydrate and dissolve it in a beaker containing an appropriate amount of deionized water. Then transfer it to a 100mL volumetric flask and make up to volume to prepare a precursor solution with a calcium ion concentration of 1mol / L and free of organic acids.

[0122] S2: A peristaltic pump is used to supply the precursor solution to the two-fluid nozzle at a flow rate of 10 mL / min. Simultaneously, compressed air at a pressure of 0.3 MPa and a flow rate of 20 L / min is supplied to the two-fluid nozzle to form a spray, i.e., the volumetric flow rate ratio of atomizing gas to precursor solution is 2000.

[0123] S3: The spray enters the high-temperature heated through-cavity at 600℃ and undergoes pyrolysis.

[0124] S4: Collect the pyrolysis products and calcine them in a high-temperature furnace at 850°C under air atmosphere for 10 minutes to obtain spherical calcium-based carbon dioxide adsorbent, i.e., sample 9.

[0125] The performance of sample 9 was verified, and the specific results are as follows: See Figure 17 , Figure 17 (a) is the SEM image of sample 9 at 1000x magnification; (b) is the SEM image of sample 9 at 15000x magnification; and (c) is the SEM image of sample 9 at 120000x magnification.

[0126] Depend on Figure 17 It can be seen that the calcium-based carbon dioxide adsorbent of sample 9 exhibits an irregularly shaped cluster structure, and the monomer surface is formed by the stacking and growth of nanocrystals to form a sheet-like structure.

[0127] See Figure 18Compared with the performance curve of commercial analytical grade CaO, the conversion rate of the spherical calcium-based carbon dioxide adsorbent of sample 9 was 75.55% in the first cycle, which was about 63.5% higher than that of analytical grade CaO (46.21%). Subsequently, its conversion rate dropped rapidly, and the conversion rate of the sample was 16.32% in the 30th cycle, which was only 11.2% higher than that of analytical grade CaO (14.67%). Its cumulative CO2 adsorption capacity after 30 cycles was 6.11 g / g, which was only about 24.8% higher than that of analytical grade CaO (4.9 g / g).

[0128] Comparative Example 3 S1: Weigh 23.615g (0.1mol) calcium nitrate tetrahydrate and 21.014g (0.1mol) citric acid monohydrate and dissolve them in a beaker containing an appropriate amount of deionized water. Then transfer the solution to a 100mL volumetric flask and make up to volume to prepare a precursor solution with a calcium ion concentration of 1mol / L and a molar ratio of organic acid to calcium ions of 1:1.

[0129] S2: A peristaltic pump is used to supply the precursor solution to the two-fluid nozzle at a flow rate of 10 mL / min. Simultaneously, compressed air at a pressure of 0.3 MPa and a flow rate of 20 L / min is supplied to the two-fluid nozzle to form a spray, i.e., the volumetric flow rate ratio of atomizing gas to precursor solution is 2000.

[0130] S3: The spray enters the high-temperature heating cavity at 800℃ and undergoes pyrolysis.

[0131] S4: Collect the pyrolysis products and calcine them in a high-temperature furnace at 850°C under air atmosphere for 10 minutes to obtain calcium-based carbon dioxide adsorbent, i.e., sample 10.

[0132] The performance of sample 10 was verified, and the specific results are as follows: See Figure 19 , Figure 19 (a) is the SEM image of sample 10 at 1000x magnification; (b) is the SEM image of sample 10 at 15000x magnification; and (c) is the SEM image of sample 10 at 120000x magnification.

[0133] Depend on Figure 19 It can be seen that the calcium-based carbon dioxide adsorbent of sample 10 exhibits an irregular hollow spherical structure or cracked and broken spherical shells and fragments, and the surface is formed by the growth of nanocrystals of about 100-200nm to form a porous network structure.

[0134] See Figure 20Compared with the performance curve of commercially available analytical grade CaO, the spherical calcium-based carbon dioxide adsorbent of sample 10 achieved a conversion rate of 92.8% in the first cycle, an increase of approximately 100.8% compared to 46.21% for analytical grade CaO. However, its conversion rate rapidly decreased with increasing cycle number, falling below that of analytical grade CaO after the 7th cycle. By the 30th cycle, the conversion rate was only 5.45%, a decrease of approximately 63.5% compared to 14.67% for analytical grade CaO. Its cumulative CO2 adsorption capacity after 30 cycles was 3.9 g / g, a decrease of approximately 20.4% compared to 4.9 g / g for analytical grade CaO. This demonstrates that pyrolysis temperature has a significant impact on the performance of calcium-based adsorbents, and temperatures exceeding the protection range of this invention cannot guarantee stable cycling performance of the calcium-based adsorbent.

[0135] Comparative Example 4 S1: Weigh 23.615 g (0.1 mol) calcium nitrate tetrahydrate and 21.014 g (0.1 mol) citric acid monohydrate and dissolve them in a beaker containing an appropriate amount of deionized water. Then transfer the solution to a 100 mL volumetric flask and make up to volume to prepare a precursor solution with a calcium ion concentration of 1 mol / L and a molar ratio of organic acid to calcium ions of 1:1.

[0136] S2: A peristaltic pump is used to supply the two-fluid nozzle at a flow rate of 10 mL / min. Simultaneously, compressed air at a pressure of 0.3 MPa and a flow rate of 5 L / min is supplied to the two-fluid nozzle, i.e., the volumetric flow rate ratio of atomizing gas to precursor solution is 500. However, due to the low supply flow rate of compressed air, a liquid spray with poor atomization, large droplets, and uneven particle size distribution is formed.

[0137] S3: The spray enters the high-temperature heated through-cavity at 600 ℃, where pyrolysis occurs. Understandably, smaller droplets undergo complete pyrolysis, producing grayish-black pyrolysis products; while larger droplets do not fully pyrolyze, producing light yellow, blocky pyrolysis products. S4: Collect the pyrolysis products and calcine them in a high-temperature furnace at 850 °C under air atmosphere for 10 min to obtain calcium-based carbon dioxide adsorbent, i.e., sample 11.

[0138] The performance of sample 11 was verified, and the specific results are as follows: See Figure 21 , Figure 21 (a) is the SEM image of sample 11 at 1000x magnification; (b) is the SEM image of sample 11 at 15000x magnification; and (c) is the SEM image of sample 11 at 120000x magnification.

[0139] Depend on Figure 21It can be seen that the calcium-based carbon dioxide adsorbent monomers of sample 11 have large particle sizes and exhibit irregular hollow spherical structures. Multiple monomers are attached to each other to form irregular clusters, and the surface of the monomers is formed by the growth of nanocrystals of about 100-200nm to form a porous network structure.

[0140] See Figure 22 Compared with the performance curve of commercially available analytical grade CaO, the spherical calcium-based carbon dioxide adsorbent of sample 11 achieved a conversion rate of 77.68% in the first cycle, an increase of approximately 68.1% compared to 46.21% for analytical grade CaO. Subsequently, its conversion rate rapidly decreased, reaching 13.76% in the 30th cycle, a decrease of 6.2% compared to 14.67% for analytical grade CaO. Its cumulative CO2 adsorption capacity after 30 cycles was 7.22 g / g, an increase of only approximately 47.4% compared to 4.9 g / g for analytical grade CaO. This demonstrates that the atomized gas-liquid volumetric flow rate ratio has a significant impact on the performance of calcium-based adsorbents, while concentrations exceeding the scope of this invention cannot effectively improve the cycling performance of calcium-based adsorbents.

[0141] Comparative Example 5 S1: Weigh 23.615g (0.1mol) calcium nitrate tetrahydrate and 21.014g (0.1mol) citric acid monohydrate and dissolve them in a beaker containing an appropriate amount of deionized water. Then transfer the solution to a 100mL volumetric flask and make up to volume to prepare a precursor solution with a calcium ion concentration of 1mol / L and a molar ratio of organic acid to calcium ions of 1:1.

[0142] S2: A peristaltic pump is used to supply the precursor solution to the two-fluid nozzle at a flow rate of 10 mL / min. Simultaneously, compressed air at a pressure of 0.3 MPa and a flow rate of 20 L / min is supplied to the two-fluid nozzle to form a spray, i.e., the volumetric flow rate ratio of atomizing gas to precursor solution is 2000.

[0143] S3: The spray enters the high-temperature heating cavity at 600℃ and undergoes pyrolysis.

[0144] S4: Collect the pyrolysis products and calcine them in a high-temperature furnace at 1000℃ under air atmosphere for 90 minutes to obtain calcium-based carbon dioxide adsorbent, namely Sample 12.

[0145] The performance of sample 12 was verified, and the specific results are as follows: See Figure 23 , Figure 23 (a) is the SEM image of sample 12 at 1000x magnification; (b) is the SEM image of sample 12 at 15000x magnification; and (c) is the SEM image of sample 12 at 120000x magnification.

[0146] Depend on Figure 23 It can be seen that the calcium-based carbon dioxide adsorbent of sample 12 exhibits an irregular spherical structure, with multiple monomers attached to each other to form irregular clusters. There are a small number of pore structures on the surface of the monomers, and the nanocrystals are severely sintered and grown to form a continuous dense structure.

[0147] See Figure 24 Compared with the performance curve of commercially available analytical grade CaO, the conversion rate of the spherical calcium-based carbon dioxide adsorbent of sample 12 in the first cycle was 27.91%, a decrease of approximately 39.6% compared to 46.21% of analytical grade CaO. In the first four cycles, this sample exhibited self-activation, meaning the conversion rate increased with increasing cycle number. From the fourth cycle onwards, the sample's conversion rate was higher than that of analytical grade CaO, but it continued to decline in subsequent cycles. At the 30th cycle, the sample's conversion rate was 21.21%, an increase of approximately 44.6% compared to 14.67% of analytical grade CaO. Its cumulative CO2 adsorption capacity after 30 cycles was 6.1 g / g, an increase of only approximately 24.5% compared to 4.9 g / g of analytical grade CaO. This demonstrates that calcination conditions play a crucial role in the performance of calcium-based adsorbents, and calcination methods exceeding the scope of this invention cannot guarantee the cycling performance of calcium-based adsorbents.

[0148] Comparative Example 6 S1: Weigh 23.615g (0.1mol) calcium nitrate tetrahydrate and 21.014g (0.1mol) citric acid monohydrate and dissolve them in a beaker containing an appropriate amount of deionized water. Then transfer the solution to a 100mL volumetric flask and make up to volume to prepare a precursor solution with a calcium ion concentration of 1mol / L and a molar ratio of organic acid (citric acid monohydrate) to calcium ions of 1.5:1.

[0149] S2: A peristaltic pump is used to supply the precursor solution to the two-fluid nozzle at a flow rate of 10 mL / min. Simultaneously, compressed air at a pressure of 0.3 MPa and a flow rate of 20 L / min is supplied to the two-fluid nozzle to form a spray, that is, the volumetric flow rate ratio of atomizing gas to precursor solution is 2000.

[0150] S3: The spray enters the high-temperature heated through-cavity at 600℃ and undergoes pyrolysis.

[0151] S4: Collect the pyrolysis products and calcine them in a high-temperature furnace at 850°C under air atmosphere for 10 minutes to obtain spherical calcium-based carbon dioxide adsorbent, i.e., sample 13.

[0152] The performance of sample 1 was verified, and the specific results are as follows: See Figure 25Compared with the performance curve of commercial analytical grade CaO, the cyclic carbon dioxide adsorbent of sample 13 showed a significant improvement in cyclic carbonation conversion rate compared with analytical grade CaO. The conversion rate in the first cycle was 91.74%, which was about 98.5% higher than that of analytical grade CaO (46.21%). The conversion rate of the sample in the 30th cycle was 24.16%, which was about 64.7% higher than that of analytical grade CaO (14.67%). Its cumulative CO2 adsorption capacity after 30 cycles was 9.92 g / g, which was about 102.5% higher than that of analytical grade CaO (4.9 g / g).

[0153] It is worth noting that the microstructure of sample 13 is not significantly different from that of sample 1, so it will not be described in detail.

[0154] The comparison of relevant parameters and sample test results for the above embodiments and comparative examples are shown in Tables 1 and 2 below, respectively: Table 1 Experimental Data Set

[0155] Table 2 Sample Test Results

[0156] Based on the above Examples 1 to 7, it is known that when the calcium ion concentration in the precursor solution is in the range of 0.1-2.5 mol / L, the molar ratio of organic acid to calcium ions is in the range of 0.5:1-2:1, the volumetric flow rate ratio of atomizing gas to precursor solution is in the range of 1000-4000, the temperature of the high-temperature zone of the high-temperature heating through-cavity is 450-700 ℃, and the parameters of the high-temperature heating furnace are set under reasonable conditions, and some solution components and atomizing gas components are selected within the above range, the first cycle conversion rate and the 30th cycle conversion rate of the prepared spherical calcium-based carbon dioxide adsorbent (hereinafter referred to as adsorbent) are significantly improved, especially when the relevant parameters are within the preferred range provided in this application.

[0157] Based on the above Examples 1, 2 and 6, it can be seen that when the calcium ion concentration in the precursor solution is in the range of 0.5-1.5 mol / L, the 30th conversion rate and the cumulative CO2 adsorption capacity after 30 cycles of the prepared adsorbent are significantly better than when the calcium ion concentration in the precursor solution is in the range of 0.4 mol / L and 2 mol / L.

[0158] Based on the above Examples 1, 3, 6 and Comparative Example 6, it can be seen that when the molar ratio of organic acid to calcium ions in the precursor solution is in the range of 0.75:1-1.25:1, the 30th conversion rate of the prepared adsorbent is significantly better than when the molar ratio of organic acid to calcium ions in the precursor solution is 0.5, 1.35 and 1.6.

[0159] Based on the above Examples 1, 4 and 6, it can be seen that when the temperature of the high-temperature region of the high-temperature heating through-cavity is in the range of 550-650℃, the 30th conversion rate and the cumulative CO2 adsorption capacity of the prepared adsorbent after 30 cycles are significantly better than when the temperature of the high-temperature region of the high-temperature heating through-cavity is 500℃ and 680℃.

[0160] Based on the above Example 1 and Comparative Example 1, it is evident that when the calcium ion concentration in the precursor solution exceeds 2 mol / L, the prepared adsorbent exhibits some performance improvement compared to analytical grade CaO, but the improvement is limited, especially in terms of the conversion rate after 30 cycles and the cumulative CO2 adsorption capacity after 30 cycles. In other words, the concentration of calcium ions in the precursor solution has a significant impact on the performance of calcium-based adsorbents, and exceeding a certain range (see the preferred scope of this application) cannot effectively improve the cycling performance of the calcium-based adsorbent.

[0161] Based on the above Examples 1 and 2, it is evident that when the precursor solution does not contain organic acids, the prepared adsorbent shows some performance improvement compared to analytical grade CaO, but the improvement is limited, especially in terms of the conversion rate after 30 cycles and the cumulative CO2 adsorption capacity after 30 cycles. In other words, the presence or absence of organic acids in the precursor solution has a significant impact on the performance of calcium-based adsorbents; without organic acids, the cycling performance of calcium-based adsorbents cannot be effectively improved.

[0162] Based on the above Examples 1 and 3, it can be seen that when the temperature inside the through-cavity is too high, although the conversion rate of the prepared adsorbent in the first cycle is improved compared with that of analytical grade CaO, the conversion rate in the 30th cycle and the cumulative CO2 adsorption capacity in the 30th cycle are significantly reduced, which seriously affects the cycling performance of the calcium-based adsorbent.

[0163] Based on the above Example 1 and Comparative Example 4, it can be seen that when the volumetric flow rates of the atomizing gas and the precursor solution are relatively small, although the conversion rate of the prepared adsorbent in the first cycle and the cumulative CO2 adsorption capacity in 30 cycles are improved to a certain extent compared with analytical grade CaO, the improvement is limited, and the conversion rate in the 30th cycle will decrease, affecting the cycling performance of the calcium-based adsorbent.

[0164] Based on the above Example 1 and Comparative Example 5, it can be seen that when the calcination temperature of the high-temperature heating furnace is too high and the calcination time is too long, the conversion rate of the prepared adsorbent in the first cycle is significantly lower than that of analytical grade CaO, while the conversion rate in the 30th cycle and the cumulative CO2 adsorption capacity in the 30th cycle have limited improvement.

[0165] The above embodiments are merely preferred embodiments of the present invention and should not be construed as limiting the scope of protection of the present invention. Any non-substantial changes and substitutions made by those skilled in the art based on the present invention shall fall within the scope of protection claimed by the present invention.

Claims

1. A method for preparing a spherical calcium-based carbon dioxide adsorbent, characterized in that, Includes the following steps: The calcium precursor and organic acid are dissolved in a solvent in a predetermined ratio to prepare a precursor solution. The precursor solution is atomized into a spray using an atomizing gas, wherein the volumetric flow rate ratio of the atomizing gas to the precursor solution is 1000-4000, preferably 1500-3000. The spray is directed into the high-temperature region of the high-temperature heating through-cavity, and the temperature of the high-temperature region is controlled within a preset pyrolysis temperature so that the spray undergoes pyrolysis and forms pyrolysis products. The pyrolysis products are collected and transferred to a high-temperature heating furnace in a predetermined environment for calcination to generate spherical calcium-based carbon dioxide adsorbent.

2. The method for preparing a spherical calcium-based carbon dioxide adsorbent according to claim 1, characterized in that, The calcium ion concentration in the precursor solution ranges from 0.1 to 2.5 mol / L, preferably from 0.5 to 2 mol / L.

3. The method for preparing a spherical calcium-based carbon dioxide adsorbent according to claim 1, characterized in that, The molar ratio of organic acid to calcium ions in the precursor solution is 0.5:1-2:1, preferably 0.75:1-1.25:

1.

4. A method for preparing a spherical calcium-based carbon dioxide adsorbent according to any one of claims 1-3, characterized in that, The calcium precursor is set as one or a combination of calcium nitrate, calcium chloride, calcium acetate, and calcium citrate. And / or, The organic acid is set as one or a combination of citric acid, formic acid, acetic acid, propionic acid, and glycine; And / or, The solvent is set as one or a combination of two of deionized water and ethanol.

5. The method for preparing a spherical calcium-based carbon dioxide adsorbent according to claim 1, characterized in that, The process of atomizing the precursor solution into a spray using atomizing gas specifically includes the following steps: The precursor solution is supplied to the dual-fluid nozzle at a preset flow rate, and at the same time, the atomizing gas is supplied to the dual-fluid nozzle at a preset flow rate and preset pressure.

6. The method for preparing a spherical calcium-based carbon dioxide adsorbent according to claim 5, characterized in that, The atomizing gas can be set to one or a combination of two of compressed air and nitrogen.

7. The method for preparing a spherical calcium-based carbon dioxide adsorbent according to claim 1, characterized in that, The preset pyrolysis temperature ranges from 450 to 700°C, preferably from 550 to 650°C.

8. The method for preparing a spherical calcium-based carbon dioxide adsorbent according to claim 1, characterized in that, The preset environment includes calcination temperature and calcination gas atmosphere. The calcination temperature ranges from 700 to 950°C, preferably from 800 to 900°C. The calcination gas atmosphere is an air atmosphere.

9. The method for preparing a spherical calcium-based carbon dioxide adsorbent according to claim 1, characterized in that, The pyrolysis products are calcined in the high-temperature heating furnace for 5-60 minutes, preferably 10-30 minutes.

10. A spherical calcium-based carbon dioxide adsorbent, characterized in that, It is prepared by the method for preparing a spherical calcium-based carbon dioxide adsorbent according to any one of claims 1-9.

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