Preparation method and application of calcium-based carbon dioxide adsorbent

Abstract

The application belongs to the technical field of environmental energy material preparation, and particularly relates to a preparation method and application of a calcium-based carbon dioxide adsorbent, which comprises preparation of a novel Si-modified calcium adsorbent material; the prepared calcium-based carbon dioxide adsorbent is loaded into an adsorption furnace to capture CO2 and reduce CO2 emission; after saturation, the adsorbent is regenerated by switching to H2, and the captured CO2 is converted into CO to produce synthesis gas (CO+H2). The deactivated composite material can be used for cement production and the like to avoid secondary pollution. CO2 is captured and converted into high-value-added chemical and energy products, which can optimize the energy structure dominated by fossil energy, effectively alleviate environmental problems, and realize full utilization of carbon resources.

Description

Technical Field

[0001] This invention belongs to the field of environmental and energy materials preparation technology, specifically relating to a method for preparing and applying a calcium-based carbon dioxide adsorbent. Background Technology

[0002] The reduction, sequestration, and reuse of the greenhouse gas carbon dioxide are important issues of concern in modern society. Bio-waste adsorbents, as promising materials for CO2 capture, have recently attracted researchers' attention. However, the adsorption capacity decay of all natural adsorbents used in the calcium cycle during the carbonation / calcination cycle is a significant challenge. The novel green calcium-based adsorbent prepared in this paper boasts a high adsorption capacity, ensuring its broad application prospects.

[0003] Chinese patent CN114870570B discloses a liquid-solid phase-separation absorbent using N-methyldiethanolamine (MDEA) as the main component. This absorbent reacts with CO2 to form carbamate, but the product exhibits poor stability, a slow CO2 absorption rate, and poor cycle performance. Chinese patent CN115364623A discloses a liquid-phase adsorbent formulated with ethanolamine (MEA). While its adsorption rate is faster compared to other amines, this patent only addresses the adsorption rate issue and does not address the adsorbent's cycle life, nor does it propose any applications for the carbon dioxide released after desorption. Summary of the Invention

[0004] To address the issue of rapid adsorption capacity decay of adsorbents during the carbonation / calcination cycle in calcium cycling, this invention synthesizes a Si-doped modified calcium-based adsorbent using the sol-gel method. Simultaneously, hydrogen is used to regenerate the adsorbent, significantly extending its lifespan and greatly increasing its adsorption capacity. The generated syngas can then be used as a raw material for the direct production of chemicals.

[0005] The preparation and process application of a medium- and high-temperature CO2 capture and in-situ conversion material disclosed in this application include the following steps:

[0006] 1. A method for preparing a calcium-based carbon dioxide adsorbent, characterized by comprising the following steps:

[0007] S1. Sol-gel derivatized adsorbents were prepared using the sol-gel method;

[0008] S2. Grind and calcine the sol-gel derived adsorbent obtained in step S1 to obtain a calcium-based carbon dioxide adsorbent.

[0009] The preparation of sol-gel derivatized adsorbents by the sol-gel method includes the following steps:

[0010] A1. After washing, drying and grinding the calcium material, calcium powder is obtained, which is then mixed with hydrochloric acid solution to prepare calcium chloride solution;

[0011] A2. After mixing calcium chloride solution with silica nanoparticles, sodium hydroxide solution is added to obtain calcium hydroxide suspension. After aging, filtration, washing and drying, sol-gel derivatized adsorbent is obtained.

[0012] In step A1, the calcium material is at least one of marble, limestone, seashell, or eggshell; the particle size of the calcium material powder is 45-75 μm; the concentration of the hydrochloric acid solution is 1-3 mol / L; and the mass ratio of the calcium material powder to the hydrochloric acid solution is 1:20-25.

[0013] In step A2, the mass ratio of calcium chloride solution to silica nanoparticles is 1:0.07-0.1; the concentration of sodium hydroxide solution is 1-3 mol / L; the mass ratio of calcium powder to sodium hydroxide solution is 21-30:1; and the aging time is 12-24 hours. In step S2, the firing process involves controlling the heating rate to rise to 700-900℃ at a rate of 5-10℃ / min and maintaining the temperature for 1-4 hours.

[0014] The application of a calcium-based carbon dioxide adsorbent prepared by the above method in carbon dioxide adsorption includes the following steps:

[0015] B1. The prepared adsorbent is loaded into two adsorption furnaces for adsorption.

[0016] After B2 adsorption saturation, the atmosphere is switched to H2 to regenerate the adsorbent, while the captured CO2 is converted into CO to produce syngas (CO+H2).

[0017] In step B1, the adsorption temperature is 500-700℃ and the adsorption pressure is 0.1-0.3 MPa.

[0018] In step B1, the raw material gas used is CO2, and 300-500 mL of raw material gas is passed through per minute for 30-40 minutes for adsorption. The remaining CO2 is then adsorbed by a secondary adsorption furnace.

[0019] In step B2, the regenerated hydrogen flow rate is 600-1000 mL / min, the temperature is 500-800℃, and the time is 30-40 minutes.

[0020] Preferably, the ball mill is used to pulverize the calcium material to 53-75 μm (325-270 mesh), the concentration of the hydrochloric acid solution is 2-3 mol / L, and the mass ratio of calcium powder to hydrochloric acid solution is 1:23-25.

[0021] Preferably, the mass ratio of calcium chloride solution to silica nanoparticles is 1:0.08-0.1; the concentration of sodium hydroxide solution is 2-3 mol / L; the mass ratio of calcium material to sodium hydroxide solution is 25-30:1; and the aging time is 22-24 hours.

[0022] Preferably, the calcination temperature is 800-900℃, and the temperature is maintained for 3-4 hours.

[0023] Preferably, the adsorption and regeneration temperatures are 500-600℃ and 700-800℃, respectively, and the adsorption pressure is 0.2-0.3 MPa.

[0024] Preferably, the raw material gas CO2 is passed through at a rate of 400-500 mL per minute, and the adsorption time is 35-40 minutes.

[0025] Preferably, after adsorption saturation, the adsorption is regenerated by H2 at a rate of 800-1000 mL / min for 35-40 minutes.

[0026] This invention provides a method for preparing a calcium-based carbon dioxide adsorbent. The calcium-based adsorbent is prepared by incorporating silicon through a sol-gel method. The incorporated silicon acts as a framework in the calcium-based adsorbent, changing its pore structure, resulting in smaller grain size, higher porosity, and a more porous structure, thus enhancing its CO2 capture capacity.

[0027] It significantly improved the cycling stability of calcium oxide, effectively prevented the sintering and agglomeration of calcium oxide at high temperatures, and delayed the sintering of the adsorbent.

[0028] Based on the electron gain and loss of H* and CO2 during surface adsorption, H* and CO2 can be considered Lewis acids, and the CaO surface can be considered a Lewis base. When hydrogen is switched to CaO, hydrogen forms hydrogen radicals (H*) on the CaO surface, covering the adsorbent surface. At this time, the basicity of CaO is weakened to a certain extent, and the ability of the Ca surface to adsorb CO2 becomes weaker. CO2 is more likely to be removed from the adsorbent and attaches to the adsorbent surface in the form of carbon dioxide radicals (CO2*). CO2* reacts with H* to produce carbon monoxide and water.

[0029] The reactions involved:

[0030] (1) Preparation process

[0031] CaCO3 + 2HCl → CaCl2 + H2O + CO2

[0032] CaCl₂ + 2NaOH → Ca(OH)₂ + 2NaCl

[0033] (2) Adsorption-desorption process

[0034] ① The reaction between flue gas and adsorbent: CaO + CO2 → CaCO3.

[0035] ② Switch H2 to regenerate the adsorbent: H2 + CaCO3 → CaO + H2O + CO.

[0036] The beneficial effects of this invention are as follows: A Si-doped modified calcium-based adsorbent was synthesized using the sol-gel method, and the adsorbent was regenerated using hydrogen, resulting in a significantly extended adsorbent lifespan and a substantial increase in adsorption capacity. After 200 cycles, the adsorption capacity showed no significant decrease. This process employs a two-stage adsorption process, where unadsorbed CO2 from the first-stage adsorption process is introduced into the second-stage adsorption unit, simultaneously yielding relatively pure syngas. This syngas can be used as a raw material for the direct synthesis of chemicals. Attached Figure Description

[0037] Figure 1 This is a schematic diagram illustrating the application of the calcium-based carbon dioxide adsorbent prepared according to the present invention.

[0038] In the diagram: 1. Combustion furnace; 2. Primary adsorption tower; 3. Primary drying tower; 4. Secondary adsorption tower; 5. Secondary drying tower; 6. Syngas storage tank. Detailed Implementation Example 1

[0039] The calcium carbonate (marble) was washed with deionized water to remove all possible contaminants. It was then dried in an oven at 60°C. The particles were then pulverized to 75 μm using a ball mill. The desired adsorbent was prepared using the sol-gel method, by mixing the calcium carbonate powder with a 1 mol / L HCl solution at a mass ratio of 1:20.

[0040] The CaCl2 sol and SiO2 nanoparticles were physically mixed at a mass ratio of 1:0.07, and a 2 mol / L NaOH solution was added. The mass ratio of NaOH solution to calcium powder was 28:1.

[0041] The prepared solution was aged at room temperature for 12 hours to obtain a gel. After filtration and washing, the gel was placed in an oven and dried at 60°C for 20 hours to obtain a sol-gel derivatized adsorbent. The adsorbent was crushed and calcined in a muffle furnace at 700°C for 1 hour with a heating rate of 5°C / min to obtain a calcium-based carbon dioxide adsorbent, named No. 1. Example 2

[0042] The calcium carbonate (limestone) was washed with deionized water to remove all possible contaminants. It was then dried in an oven at 70°C. The particles were then pulverized to 63 μm using a ball mill. The desired adsorbent was prepared using the sol-gel method, by mixing the calcium carbonate powder with a 2 mol / L HCl solution at a mass ratio of 1:21.

[0043] The CaCl2 sol and SiO2 nanoparticles were physically mixed at a mass ratio of 1:0.08, and a 3 mol / L NaOH solution was added. The mass ratio of NaOH solution to calcium powder was 22:1.

[0044] The prepared solution was aged at room temperature for 24 hours to obtain a gel. After filtration and washing, the gel was placed in an oven and dried at 70°C for 21 hours to obtain a sol-gel derivatized adsorbent. The adsorbent was crushed and calcined in a muffle furnace at 800°C for 4 hours at a heating rate of 10°C / min to obtain a calcium-based carbon dioxide adsorbent, named #2. Example 3

[0045] The calcium carbonate material (shells) was washed with deionized water to remove all possible contaminants. Then, it was dried in an oven at 80°C. The particles were then pulverized to 53 μm using a ball mill. The desired adsorbent was prepared using the sol-gel method, by mixing the calcium carbonate powder with a 3 mol / L HCl solution at a mass ratio of 1:22.

[0046] The CaCl2 sol and SiO2 nanoparticles were physically mixed at a mass ratio of 1:0.09, and a 1 mol / L NaOH solution was added. The mass ratio of NaOH solution to calcium powder was 21:1.

[0047] The prepared solution was aged at room temperature for 18 hours to obtain a gel. After filtration and washing, the gel was placed in an oven and dried at 90°C for 22 hours to obtain a sol-gel derivatized adsorbent. The adsorbent was crushed and calcined in a muffle furnace at 900°C for 3 hours with a heating rate of 8°C / min to obtain a calcium-based carbon dioxide adsorbent, named #3. Example 4

[0048] The calcium material (eggshells) was washed with deionized water to remove all possible contaminants. Then, it was dried in an oven at 90°C. The particles were then pulverized to 45 μm using a ball mill. The desired adsorbent was prepared using the sol-gel method, by mixing the calcium powder with a 2 mol / L HCl solution at a mass ratio of 1:23.

[0049] The CaCl2 sol and SiO2 nanoparticles were physically mixed at a mass ratio of 1:0.1, and a 3 mol / L NaOH solution was added. The mass ratio of NaOH solution to calcium powder was 24:1.

[0050] The prepared solution was aged at room temperature for 24 hours to obtain a gel. After filtration and washing, the gel was placed in an oven and dried at 80°C for 23 hours to obtain a sol-gel derivatized adsorbent. The adsorbent was crushed and calcined in a muffle furnace at 800°C for 2 hours with a heating rate of 8°C / min to obtain a calcium-based carbon dioxide adsorbent, named #4. Example 5

[0051] The calcium carbonate material (marble, limestone) was washed with deionized water to remove all possible contaminants. Then, it was dried in an oven at 100°C. The particles were then pulverized to 63 μm using a ball mill. The desired adsorbent was prepared using the sol-gel method, by mixing the calcium carbonate powder with a 3 mol / L HCl solution at a mass ratio of 1:24.

[0052] The CaCl2 sol and SiO2 nanoparticles were physically mixed at a mass ratio of 1:0.08, and a 2 mol / L NaOH solution was added. The mass ratio of NaOH solution to calcium powder was 25:1.

[0053] The prepared solution was aged at room temperature for 18 hours to obtain a gel. After filtration and washing, the gel was placed in an oven and dried at 60°C for 24 hours to obtain a sol-gel derivatized adsorbent. The adsorbent was crushed and calcined in a muffle furnace at 800°C for 4 hours with a heating rate of 7°C / min to obtain a calcium-based carbon dioxide adsorbent, named #5. Example 6

[0054] The calcium materials (marble, shells, eggshells) were washed with deionized water to remove all possible contaminants. They were then dried in an oven at 80°C. The particles were then pulverized to 75 μm using a ball mill. The desired adsorbent was prepared using the sol-gel method, by mixing the calcium powder with a 1 mol / L HCl solution at a mass ratio of 1:25.

[0055] The CaCl2 sol and SiO2 nanoparticles were physically mixed at a mass ratio of 1:0.09, and a 1 mol / L NaOH solution was added. The mass ratio of NaOH solution to calcium powder was 26:1.

[0056] The prepared solution was aged at room temperature for 12 hours to obtain a gel. After filtration and washing, the gel was placed in an oven and dried at 80°C for 22 hours to obtain a sol-gel derivatized adsorbent. The adsorbent was crushed and calcined in a muffle furnace at 900°C for 3 hours with a heating rate of 6°C / min to obtain a calcium-based carbon dioxide adsorbent, named #6. Example 7

[0057] The calcium materials (marble, limestone, shells, eggshells) were washed with deionized water to remove all possible contaminants. They were then dried in an oven at 70°C. The particles were then pulverized to 45 μm using a ball mill. The desired adsorbent was prepared using the sol-gel method, by mixing the calcium powder with a 3 mol / L HCl solution at a mass ratio of 1:22.

[0058] The CaCl2 sol and SiO2 nanoparticles were physically mixed at a mass ratio of 1:0.08, and a 3 mol / L NaOH solution was added. The mass ratio of NaOH solution to calcium powder was 23:1.

[0059] The prepared solution was aged at room temperature for 24 hours to obtain a gel. After filtration and washing, the gel was placed in an oven and dried at 90°C for 20 hours to obtain a sol-gel derivatized adsorbent. The adsorbent was crushed and calcined in a muffle furnace at 700°C for 2 hours with a heating rate of 9°C / min to obtain a calcium-based carbon dioxide adsorbent, named #7. Example 8

[0060] The calcium materials (limestone, shells) were washed with deionized water to remove all possible contaminants. They were then dried in an oven at 90°C. The particles were then pulverized to 45 μm using a ball mill. The desired adsorbent was prepared using the sol-gel method, by mixing the calcium powder with a 2 mol / L HCl solution at a mass ratio of 1:23.

[0061] The CaCl2 sol and SiO2 nanoparticles were physically mixed at a mass ratio of 1:0.1, and a 2 mol / L NaOH solution was added. The mass ratio of NaOH solution to calcium powder was 27:1.

[0062] The prepared solution was aged at room temperature for 18 hours to obtain a gel. After filtration and washing, the gel was placed in an oven and dried at 70°C for 24 hours to obtain a sol-gel derived adsorbent. The adsorbent was crushed and calcined in a muffle furnace at 700°C for 4 hours at a heating rate of 10°C / min to obtain a calcium-based carbon dioxide adsorbent, named No. 8. Example 9

[0063] The calcium-containing materials (shells, eggshells) were washed with deionized water to remove all possible contaminants. They were then dried in an oven at 100°C. The particles were then pulverized to 75 μm using a ball mill. The desired adsorbent was prepared using the sol-gel method, by mixing the calcium powder with a 1 mol / L HCl solution at a mass ratio of 1:25.

[0064] The CaCl2 sol and SiO2 nanoparticles were physically mixed at a mass ratio of 1:0.08, and a 2 mol / L NaOH solution was added. The mass ratio of NaOH solution to calcium powder was 29:1.

[0065] The prepared solution was aged at room temperature for 12 hours to obtain a gel. After filtration and washing, the gel was placed in an oven and dried at 60°C for 21 hours to obtain a sol-gel derivatized adsorbent. The adsorbent was crushed and calcined in a muffle furnace at 800°C for 1 hour with a heating rate of 5°C / min to obtain a calcium-based carbon dioxide adsorbent, named No. 9. Example 10

[0066] The calcium materials (limestone, shells, eggshells) were washed with deionized water to remove all possible contaminants. They were then dried in an oven at 60°C. The particles were then pulverized to 53 μm using a ball mill. The desired adsorbent was prepared using the sol-gel method, by mixing the calcium powder with a 3 mol / L HCl solution at a mass ratio of 1:20.

[0067] After physically mixing the CaCl2 sol and SiO2 nanoparticles at a mass ratio of 1:0.07, a 1 mol / L NaOH solution was added, with the mass ratio of NaOH solution to calcium powder being 30:1.

[0068] The prepared solution was aged at room temperature for 24 hours to obtain a gel. After filtration and washing, the gel was placed in an oven and dried at 90°C for 23 hours to obtain a sol-gel derived adsorbent. The adsorbent was crushed and calcined in a muffle furnace at 700°C for 3 hours with a heating rate of 6°C / min to obtain a calcium-based carbon dioxide adsorbent. Comparative Example 11

[0069] The calcium materials (limestone, shells, eggshells) were washed with deionized water to remove all possible contaminants. They were then dried in an oven at 60°C. The particles were then pulverized to 53 μm using a ball mill. The desired adsorbent was prepared using the sol-gel method, by mixing the calcium powder with a 3 mol / L HCl solution at a mass ratio of 1:20.

[0070] Add 1 mol / L NaOH solution to the CaCl2 sol above, with the mass ratio of NaOH solution to calcium powder being 30:1.

[0071] The prepared solution was aged at room temperature for 24 hours to obtain a gel. After filtration and washing, the gel was placed in an oven and dried at 90°C for 23 hours to obtain a sol-gel derived adsorbent. The adsorbent was crushed and calcined in a muffle furnace at 700°C for 3 hours with a heating rate of 6°C / min to obtain calcium-based carbon dioxide adsorbent 11#.

[0072] Example 12

[0073] The adsorbent was packed into two quartz tubes, with 10g of adsorbent #1 and 10g of adsorbent #2 used. Using CO2 as the feed gas, the primary and secondary adsorption furnaces were heated to 500℃ and the pressure was 0.1 MPa. 300 mL of feed gas was introduced per minute for adsorption for 30 minutes, and excess CO2 was transferred to the secondary adsorption furnace. Subsequently, 600 mL of H2 was introduced per minute at atmospheric pressure into the primary adsorption furnace for regeneration for 30 minutes. After dehydration by molecular sieve, the adsorbent was introduced into another adsorption furnace for further regeneration, with the desorption temperature controlled at 600℃. After further dehydration by molecular sieve, the process was repeated 20 times. The syngas (H2 + CO) was then analyzed by chromatography. The results showed that the contents of CO2, H2, and CO were 1.2%, 50.6%, and 48.2%, respectively. Example 13

[0074] The adsorbent was packed into two quartz tubes, with 10g each of adsorbent #2 and #3. Using CO2 as the feed gas, the primary and secondary adsorption furnaces were heated to 500℃ and 600℃ respectively, at a pressure of 0.2 MPa, and 400 mL of feed gas was introduced per minute for adsorption for 35 minutes. Excess CO2 was then introduced into the secondary adsorption furnace for regeneration at atmospheric pressure with 800 mL of H2 per minute. After dehydration by molecular sieve, the adsorbent was introduced into another adsorption furnace for further regeneration, with the desorption temperature controlled at 600℃. After further dehydration by molecular sieve, the mixture was cycled 40 times. The syngas (H2+CO) was then analyzed by chromatography. The results showed that the contents of CO2, H2, and CO were 2.4%, 51.2%, and 46.4%, respectively. Example 14

[0075] The adsorbent was packed into two quartz tubes, using 10g each of adsorbent #3 and #6. Using CO2 as the feed gas, the primary and secondary adsorption furnaces were heated to 600℃ and 650℃ respectively, with a pressure of 0.3 MPa. 500 mL of feed gas was introduced per minute for adsorption for 40 minutes, and excess CO2 was transferred to the secondary adsorption furnace. Subsequently, 1000 mL of H2 was introduced into the primary adsorption furnace at atmospheric pressure for regeneration for 40 minutes. After dehydration via molecular sieve, the adsorbent was passed into another adsorption furnace for further regeneration, with the desorption temperature controlled at 650℃. After further dehydration via molecular sieve, the process was repeated 60 times. The syngas (H2+CO) was then collected for chromatographic analysis. The results showed that the contents of CO2, H2, and CO were 3.8%, 51.9%, and 44.3%, respectively. Example 15

[0076] The adsorbent was packed into two quartz tubes, with 10g each of adsorbent #6 and #10. Using CO2 as the feed gas, the primary and secondary adsorption furnaces were heated to 500℃ and 650℃ respectively, at a pressure of 0.1 MPa. 300 mL of feed gas was introduced per minute for adsorption for 30 minutes, and excess CO2 was transferred to the secondary adsorption furnace. Subsequently, 600 mL of H2 was introduced per minute at atmospheric pressure into the primary adsorption furnace for regeneration for 30 minutes. After dehydration via molecular sieve, the adsorbent was transferred to another adsorption furnace for further regeneration, with the desorption temperature controlled at 650℃. After further dehydration via molecular sieve, the process was repeated 80 times. The syngas (H2+CO) was then analyzed by chromatography. The results showed that the contents of CO2, H2, and CO were 4.3%, 52.1%, and 43.6%, respectively. Example 16

[0077] The adsorbent was packed into two quartz tubes, using 10g each of adsorbent #8 and #9. Using CO2 as the feed gas, the primary and secondary adsorption furnaces were heated to 550℃ and 650℃ respectively, with a pressure of 0.1 MPa. 400 mL of feed gas was introduced per minute for adsorption for 35 minutes, and excess CO2 was transferred to the secondary adsorption furnace. Subsequently, 800 mL of H2 was introduced per minute at atmospheric pressure into the primary adsorption furnace for regeneration for 35 minutes. After dehydration via molecular sieve, the adsorbent was transferred to another adsorption furnace for further regeneration, with the desorption temperature controlled at 700℃. After further dehydration via molecular sieve, the mixture was cycled 100 times. The syngas (H2 + CO) was then analyzed by chromatography. The results showed that the contents of CO2, H2, and CO were 3.4%, 51.7%, and 44.9%, respectively. Example 17

[0078] The adsorbent was packed into two quartz tubes, using 10g each of adsorbent #2 and #5. Using CO2 as the feed gas, the primary and secondary adsorption furnaces were heated to 600℃ and 700℃ respectively, with a pressure of 0.2 MPa. 500 mL of feed gas was introduced per minute for adsorption for 40 minutes, and excess CO2 was transferred to the secondary adsorption furnace. Subsequently, 1000 mL of H2 was introduced into the primary adsorption furnace at atmospheric pressure for regeneration for 40 minutes. After dehydration via molecular sieve, the adsorbent was passed into another adsorption furnace for further regeneration, with the desorption temperature controlled at 700℃. After further dehydration via molecular sieve, the mixture was cycled 120 times. The syngas (H2+CO) was then analyzed by chromatography. The results showed that the contents of CO2, H2, and CO were 4.1%, 52%, and 43.9%, respectively. Example 18

[0079] The adsorbent was packed into two quartz tubes, using 10g each of adsorbent #3 and #7. Using CO2 as the feed gas, the primary and secondary adsorption furnaces were heated to 550℃ and 550℃ respectively, with a pressure of 0.3 MPa. 600 mL of feed gas was introduced per minute for adsorption for 30 minutes, and excess CO2 was transferred to the secondary adsorption furnace. Subsequently, H2 was introduced into the primary adsorption furnace at atmospheric pressure at a rate of 60 mL per minute for regeneration for 35 minutes. After dehydration via molecular sieve, the adsorbent was introduced into another adsorption furnace for further regeneration, with the desorption temperature controlled at 700℃. After further dehydration via molecular sieve, the mixture was cycled 140 times. The syngas (H2+CO) was then analyzed by chromatography. The results showed that the contents of CO2, H2, and CO were 4.4%, 52.3%, and 43.3%, respectively. Example 19

[0080] The adsorbent was packed into two quartz tubes, using 10g each of adsorbent #4 and #6. Using CO2 as the feed gas, the primary and secondary adsorption furnaces were heated to 500℃ and 550℃ respectively, with a pressure of 0.1 MPa. 400 mL of feed gas was introduced per minute for adsorption for 35 minutes, and excess CO2 was transferred to the secondary adsorption furnace. Subsequently, 800 mL of H2 was introduced per minute at atmospheric pressure into the primary adsorption furnace for regeneration for 35 minutes. After dehydration via molecular sieve, the adsorbent was transferred to another adsorption furnace for further regeneration, with the desorption temperature controlled at 800℃. After further dehydration via molecular sieve, the mixture was cycled 160 times. The syngas (H2 + CO) was then analyzed by chromatography. The results showed that the contents of CO2, H2, and CO were 4.8%, 52.4%, and 42.8%, respectively. Example 20

[0081] The adsorbent was packed into two quartz tubes, with 10g each of adsorbent #4 and #4. Using CO2 as the feed gas, the primary and secondary adsorption furnaces were heated to 600℃ and 700℃ respectively, at a pressure of 0.2 MPa, and 600 mL of feed gas was introduced per minute for adsorption for 40 minutes. Excess CO2 was then introduced into the secondary adsorption furnace. Subsequently, 1000 mL of H2 was introduced into the primary adsorption furnace at atmospheric pressure for regeneration for 40 minutes. After dehydration by molecular sieve, the adsorbent was introduced into another adsorption furnace for further regeneration, with the desorption temperature controlled at 800℃. After further dehydration by molecular sieve, the mixture was cycled 180 times. The syngas (H2+CO) was then collected for chromatographic analysis. The results showed that the contents of CO2, H2, and CO were 5.7%, 52.8%, and 41.5%, respectively. Example 21

[0082] The adsorbent was packed into two quartz tubes, with 10g each of adsorbent #2 and #5. Using CO2 as the feed gas, the primary and secondary adsorption furnaces were heated to 550℃ and 700℃ respectively, at a pressure of 0.1 MPa. 300 mL of feed gas was introduced per minute for adsorption for 35 minutes, and excess CO2 was transferred to the secondary adsorption furnace. Subsequently, 600 mL of H2 was introduced per minute at atmospheric pressure into the primary adsorption furnace for regeneration for 35 minutes. After dehydration by molecular sieve, the adsorbent was transferred to another adsorption furnace for further regeneration, with the desorption temperature controlled at 800℃. After further dehydration by molecular sieve, the mixture was cycled 200 times. The syngas (H2+CO) was then analyzed by chromatography. The results showed that the contents of CO2, H2, and CO were 5.2%, 52.6%, and 42.2%, respectively. Comparative Example 1

[0083] The adsorbent was packed into two quartz tubes. Using 20g of adsorbent #11 and CO2 as the feed gas, the primary and secondary adsorption furnaces were heated to 500℃ and pressured at 0.1MPa, with 300mL of feed gas introduced per minute for 30 minutes. Excess CO2 was then introduced into the secondary adsorption furnace for regeneration at atmospheric pressure with 600mL of H2 per minute. After dehydration by molecular sieve, the adsorbent was introduced into another adsorption furnace for further regeneration, with the desorption temperature controlled at 600℃. After further dehydration by molecular sieve, the mixture was cycled 20 times. The syngas (H2+CO) was then analyzed by chromatography. The results showed that the contents of CO2, H2, and CO were 12.3%, 56.1%, and 31.6%, respectively. Comparative Example 2

[0084] The adsorbent was packed into two quartz tubes, with 10g of adsorbent #1 and 10g of adsorbent #2. Using CO2 as the feed gas, the primary and secondary adsorption furnaces were heated to 500℃ and the pressure was 0.1 MPa. 300 mL of feed gas was introduced per minute for 30 minutes of adsorption. Excess CO2 was then introduced into the secondary adsorption furnace for regeneration at atmospheric pressure with 600 mL of N2 per minute. After dehydration by molecular sieve, the adsorbent was introduced into another adsorption furnace for further regeneration, with the desorption temperature controlled at 600℃. After further dehydration by molecular sieve, the mixture was cycled 20 times. The syngas (H2+CO) was then analyzed by chromatography. The results showed that the CO2 content was only 0.1%, with the remainder being N2, indicating that the adsorbent could no longer be regenerated.

[0085]

[0086] In summary, in the long-term life assessment, comparing Example 12 and Comparative Example 1, it was found that the calcium oxide adsorbent prepared by this invention has significantly better stability than traditional calcium carbonate. In Comparative Example 1, the Si-modified catalyst has smaller grain size and higher porosity, resulting in a more porous structure, which significantly improves the cycling stability of calcium oxide and effectively prevents sintering and agglomeration of calcium oxide at high temperatures, thus facilitating CO2 adsorption. Comparing Example 12 and Comparative Example 2, it was found that calcium cycling is achieved by switching H2, and desorption under a hydrogen atmosphere also has a significant impact on the adsorption stability of calcium oxide. However, in Comparative Example 2, N2 has no regeneration cycling capability. Example 21 showed that the adsorption capacity did not decrease significantly after 200 cycles. This is mainly due to the regeneration of the adsorbent achieved by switching the atmosphere, which significantly improves the cycling stability of CaO in carbon capture. In practical applications, the calcium oxide adsorbent prepared by this invention can be used in CO2 capture and storage technology for flue gas. Passing flue gas into an adsorption bed containing calcium oxide adsorbent can effectively adsorb CO2 and convert it into calcium carbonate. Then, the adsorbent is regenerated by heating, depressurizing, and introducing H2, releasing CO and directly converting it into syngas.

[0087] Referring to the accompanying drawings, the present invention also discloses the application of the calcium-based carbon dioxide adsorbent prepared using the above embodiments. It can be placed in a primary adsorption tower 2 and a secondary adsorption tower 4. The flue gas generated by the combustion furnace 1 in the figure passes sequentially through the primary adsorption tower 2, the primary drying tower 3, the secondary adsorption tower 4, and the secondary drying tower 5. After adsorption saturation, it is infused with hydrogen and then converted into syngas, finally flowing into a syngas storage tank 6. The generated syngas can be used as a raw material to directly synthesize chemicals.

Claims

1. A method for preparing a calcium-based carbon dioxide adsorbent, characterized in that: Includes the following steps: S1. Sol-gel derived adsorbents were prepared using the sol-gel method; S2. The sol-gel derived adsorbent is crushed and calcined to obtain a calcium-based carbon dioxide adsorbent; The preparation of sol-gel derivatized adsorbents by the sol-gel method includes the following steps: A1. After washing, drying and grinding the calcium material, calcium powder is obtained, which is then mixed with hydrochloric acid solution to prepare calcium chloride solution; A2. After mixing calcium chloride solution with silica nanoparticles, sodium hydroxide solution is added to obtain calcium hydroxide suspension. After aging, filtration, washing and drying, sol-gel derivatized adsorbent is obtained.

2. The preparation method according to claim 1, characterized in that, In step A1, the calcium material is at least one of marble, limestone, seashell, or eggshell; the particle size of the calcium material powder is 45-75 μm; the concentration of the hydrochloric acid solution is 1-3 mol / L; and the mass ratio of the calcium material powder to the hydrochloric acid solution is 1:20-25.

3. The preparation method according to claim 1, characterized in that, In step A2, the mass ratio of calcium chloride solution to silica nanoparticles is 1:0.07-0.1; the concentration of sodium hydroxide solution is 1-3 mol / L; the mass ratio of calcium powder to sodium hydroxide solution is 21-30:1; and the aging time is 12-24 hours.

4. The preparation method according to claim 1, characterized in that, In step S2, the calcination process involves controlling the heating rate to rise to 700-900℃ at a rate of 5-10℃ / min and maintaining the temperature for 1-4 hours.

5. The application of a calcium-based carbon dioxide adsorbent prepared by the preparation method according to any one of claims 1-4 in carbon dioxide adsorption, characterized in that, Includes the following steps: B1. Fill the adsorption furnace with calcium-based carbon dioxide adsorbent; B2. CO2 raw material gas is introduced into the adsorption furnace and reacts with the calcium-based carbon dioxide adsorbent. The calcium-based carbon dioxide adsorbent is oxidized to produce calcium carbonate. B3. After adsorption saturation, hydrogen gas is introduced into the adsorption furnace to react with calcium carbonate to produce calcium-based carbon dioxide adsorbent, water and carbon monoxide. In step B1, the prepared adsorbent is loaded into two adsorption furnaces for adsorption.

6. The application of the calcium-based carbon dioxide adsorbent according to claim 5 in carbon dioxide adsorption, characterized in that, In step B1, the adsorption temperature is 500-700℃ and the adsorption pressure is 0.1-0.3 MPa.

7. The application of the calcium-based carbon dioxide adsorbent according to claim 5 in carbon dioxide adsorption, characterized in that, In step B1, the raw material gas used is CO2, and 300-500 mL of raw material gas is passed through per minute for 30-40 minutes for adsorption. The remaining CO2 is then adsorbed by a secondary adsorption furnace.

8. The application of the calcium-based carbon dioxide adsorbent according to claim 5 in carbon dioxide adsorption, characterized in that, In step B2, the regenerated hydrogen flow rate is 600-1000 mL / min, the temperature is 500-800℃, and the time is 30-40 minutes.

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