A method for producing a calcium-based sorbent, a calcium-based sorbent and use thereof

Abstract

The present application relates to a kind of preparation method of calcium-based absorbent, calcium-based absorbent and its purposes.The preparation method of calcium-based absorbent of the present application includes the following steps: step 1) calcium-based raw material is prepared to contain calcium oxide raw material by calcination;Step 2) the calcium oxide-containing raw material is mixed with glycerol, to obtain a mixture;Step 3) the mixture is modified by solvothermal to obtain slurry;Step 4) the slurry is calcined to obtain calcium-based absorbent.The present application has prepared calcium-based absorbent with loose structure, simple preparation process, cheap raw materials, and can be applied to mass production.The calcium-based absorbent of the present application has high cyclic conversion rate and stable pore structure, and is not easy to sinter inactivation, has the advantages of high efficiency, excellent performance, good pollutant treatment effect, etc.Even if carbon dioxide and sulfur dioxide are repeatedly absorbed, it can still maintain good gas absorption capacity.

Description

Technical Field

[0001] This invention relates to a method for preparing a calcium-based absorbent, the calcium-based absorbent itself, and its applications, belonging to the field of environmental pollution control and clean combustion technology. Background Technology

[0002] CO2 capture, utilization, and storage (CCS) technology is considered one of the most promising emission reduction technologies. This technology involves capturing CO2 from large stationary carbon emission sources such as coal-fired power plants and cement plants, then compressing the high-concentration CO2 and transporting it to chemical plants for utilization or for geological storage, thereby controlling CO2 emissions.

[0003] Meanwhile, both coal-fired and biomass-fired boilers generate significant amounts of SO2 and other pollutants during power generation. Biomass boilers, in particular, offer the advantage of being cleaner and more sustainable than coal-fired boilers for power generation or steam production. However, with increasing environmental pressures, although biomass itself has lower sulfur and ash content (compared to coal), considering the lower calorific value of biomass fuel, the calculated sulfur and nitrogen emissions per unit of calorific value are not advantageous. Especially with the introduction of ultra-low emission standards in China, sulfur and nitrogen emissions during biomass fuel combustion cannot be ignored.

[0004] Calcium-based carbon dioxide capture technology is considered one of the most promising post-combustion CO2 capture techniques, and it can be directly applied to conventional coal-fired power plants, cement plants, and steel plants. The principle is as follows: flue gas containing 15-40% CO2 is passed into a carbonation reactor. A calcium oxide-based absorbent absorbs the CO2, and the resulting carbonation products are transported via a series fluidized bed system to a higher-temperature calcination reactor, where the calcium oxide absorbent is regenerated. Simultaneously, a high concentration of CO2 is obtained for compression, transportation, and eventual geological sequestration. The regenerated calcium oxide absorbent is then returned to the carbonation reactor for further CO2 capture. This technology offers several advantages: 1. Abundant and inexpensive absorbent precursors are naturally occurring; 2. Theoretically, it possesses superior chemical reaction kinetics; 3. Theoretically, it has a relatively high CO2 absorption capacity and can be recycled; 4. It does not require modification of existing boiler units; 5. The technology is low-cost and has good commercial application prospects; 6. This method is environmentally friendly and does not produce any secondary pollution. Based on calcium-based CO2 capture technology, the reaction equations are: in the carbonation reactor, CaO + CO2 → CaCO3; in the calcination reactor, CaCO3 → CaO + CO2↑. Additionally, calcium-based absorbent technology for capturing SO2 from flue gas is also widely applicable to environments such as power plant desulfurization, effectively absorbing SO2 gas that causes environmental pollution; the reaction equation is: CaO + SO2 → CaSO3.

[0005] However, natural calcium-based absorbents exhibit poor reactivity in capturing carbon dioxide and sulfur dioxide, resulting in low conversion rates in practical applications and significant energy consumption during production. To improve the reactivity of calcium-based absorbents, researchers have conducted a series of investigations; however, high-performance materials often have high preparation costs, while simple modification treatments are insufficient to achieve high-efficiency capture of carbon dioxide / sulfur dioxide pollutants.

[0006] Existing studies have shown that various modification methods have different effects on improving the reactivity and cycle stability of calcium-based absorbents, but they all have certain problems and drawbacks. For example, the cost of absorbents has not been significantly reduced, or the preparation cycle of absorbents is lengthy and complex, and some even produce secondary pollution. Organic acid modification has recently been considered one of the promising methods for modifying calcium-based absorbents. This involves reacting organic acids with calcium-based absorbents to generate organic calcium acids or form calcium-based complexes. After a simple heat treatment, the functional groups of these organic calcium acids or complexes rapidly decompose, forming modified calcium-based absorbents with well-developed pore structures and loose texture.

[0007] The reported organic acid modification methods each have their own advantages and disadvantages. The results of this literature review are preliminarily categorized by technical method as follows:

[0008] (1) Wu et al.[1] A method for modifying calcium-based absorbents with ethanol has been disclosed, which reduces the decay rate of carbonation conversion to some extent. However, CaO or CaCO3 itself does not react with ethanol and is insoluble in ethanol, resulting in a small interaction and insufficient improvement in the final carbon capture capacity.

[0009] (2) Imani et al. [2] A method for modifying CaCO3 particles with acetic acid has been disclosed, which increases both conversion rate and porosity. However, the problem of high price and cost remains unsolved, and the process is relatively complicated.

[0010] (3) Sun et al. [3] A method for modifying calcium-based absorbents with propionic acid is disclosed. Propionic acid modification improves the CO2 capture activity and sulfation reaction activity of the calcium-based absorbent, and the resulting absorbent has a good pore structure, but the cost is high and it cannot be recycled.

[0011] (4) Li et al. [4] A method for modifying cellulose pyrolysis tar adsorbents has been disclosed, which can significantly improve anti-sintering performance, but the process is complex, difficult to implement, and cannot be recycled.

[0012] (5) Quan et al. [5] A method for modifying waste eggshells with citric acid has been disclosed, which can significantly improve the porosity of the adsorbent, but the cost is high.

[0013] It is evident that organic acid modification can improve the reactivity of calcium-based absorbents in carbonation (CO2 capture) and sulfation (SO2 capture) to some extent. However, the preparation cost of the absorbent remains high, and the simple modification methods reported in the literature have not yet achieved ideal CO2 and SO2 capture efficiencies. Developing high-performance, low-cost absorbents for the capture of carbon dioxide and sulfur dioxide remains a key research topic in academia.

[0014] References:

[0015] [1] Wu Hao. Study on CO2 capture by cyclic calcination / carbonation of calcium-based absorbent [D]. Jiangsu: Nanjing Normal University, 2020.

[0016] [2]Mehri Imani,Maryam Tahmasebpoor,Pedro Enrique Sánchez-Jiménez,etal.Improvement in cyclic CO2 capture performance and fluidization behavior ofeggshell-derived CaCO3 particles modified with acetic acid used in calciumlooping process[J].Journal of CO2 Utilization,65(2022),102207.

[0017] [3]Rongyue Sun,Yingjie Li,Jianli Zhao,et al.CO2 capture using carbideslag modified by propionic acid in calcium looping process for hydrogenproduction[J].International Journal of Hydrogen Energy,2013,38(31):13655-13663.

[0018] [4]Chongcong Li,Xingli Gong,Hao Zhang,et al.CO2 capture performanceof CaO-based sorbent modified with torrefaction condensate during calciumlooping cycles[J].Chemical Engineering Journal,469(2023),144004.

[0019] [5]Cui Quan,Maria Cortazar,Laura Santamaria,et al.Valorization ofwaste eggshell for CO2 sorbents production by sol-gel citric acid treatmentin a fixed-bed reactor[J].Journal of CO2 Utilization,75(2023),102562. Summary of the Invention

[0020] The problem the invention aims to solve

[0021] To address the technical problems existing in the prior art, this invention provides a method for preparing a calcium-based absorbent, the calcium-based absorbent itself, and its applications. The method for preparing the calcium-based absorbent of this invention can produce a uniformly structured calcium-based absorbent, can utilize large quantities of crude glycerol (the largest byproduct in biodiesel production) in industry, is environmentally friendly, low-cost, and can significantly modify the calcium-based absorbent, making it less prone to sintering and deactivation, and suitable for multiple cycles of absorption.

[0022] Solution for solving the problem

[0023] [1] A method for preparing a calcium-based absorbent, characterized by comprising the following steps:

[0024] Step 1) Calcine the calcium-based raw material to obtain a raw material containing calcium oxide;

[0025] Step 2) Mix the raw material containing calcium oxide with glycerol to obtain a mixture;

[0026] Step 3) The mixture is subjected to solvothermal modification to obtain a slurry;

[0027] Step 4) Calcine the slurry to obtain a calcium-based absorbent.

[0028] [2] According to the preparation method described in [1], in step 1), the calcium-based raw material is one or more of limestone, snail shell or seashell.

[0029] [3] According to the preparation method described in [1] or [2], wherein in step 1), the particle size of the raw material containing calcium oxide is 20 μm to 2 mm.

[0030] [4] The preparation method according to any one of [1] to [3], wherein, in step 1), the calcination temperature is 700℃ to 1100℃.

[0031] [5] The preparation method according to any one of [1] to [4], wherein, in step 2), the content of the raw material containing calcium oxide is 2 to 5 wt% based on the total mass of the mixture.

[0032] [6] The preparation method according to any one of [1] to [5], wherein in step 3), the temperature of the solvothermal modification is 120°C to 200°C and the time is 10 to 20 hours.

[0033] [7] The preparation method according to any one of [1] to [6], wherein, in step 4), the calcination temperature is 700°C to 900°C.

[0034] [8] The preparation method according to any one of [1] to [7] further includes the following steps:

[0035] Step 5) Grind and sieve the calcium-based absorbent to ensure that the particle size of the calcium-based absorbent does not exceed 0.3 mm.

[0036] [9] A calcium-based absorbent, which is a calcium-based absorbent obtained according to any one of [1] to [8].

[0037]

[10] The calcium-based absorbent described in [9] is used for absorbing carbon dioxide or sulfur dioxide.

[0038] The effects of the invention

[0039] The method for preparing the calcium-based absorbent of this invention involves modifying the calcium-based absorbent with a large quantity of industrially available crude glycerol, resulting in a loosely structured calcium-based absorbent. The preparation process is simple, uses inexpensive raw materials, and can be applied to large-scale production. The calcium-based absorbent of this invention exhibits high cycle conversion rate and a stable pore structure, and is not prone to sintering and deactivation. It possesses advantages such as high efficiency, excellent performance, and good pollutant treatment effect. Even after multiple cycles of absorbing carbon dioxide and sulfur dioxide, it maintains good gas absorption capacity. Attached Figure Description

[0040] Figure 1 The CO2 capture capacity of the calcium-based absorbents prepared at different modification times in Example 1 of this invention after 40 cycles of calcination is shown in the figure.

[0041] Figure 2 The CO2 capture capacity of the calcium-based absorbents prepared at different modification temperatures in Example 2 of this invention after 40 cycles of calcination is shown in the figure.

[0042] Figure 3 The CO2 capture capacity of the calcium-based absorbent prepared by adding different additives in Example 3 of this invention after 40 cycles of calcination is shown in the figure.

[0043] Figure 4 SEM image of calcium-based absorbent 3-3 after 40 cycles of calcination in Example 3 of this invention.

[0044] Figure 5 SEM image of the calcium-based absorbent of Comparative Example 1 of the present invention after 40 cycles of calcination. Detailed Implementation

[0045] Various exemplary embodiments, features, and aspects of the present invention will be described in detail below. The term "exemplary" as used herein means "serving as an example, embodiment, or illustration." Any embodiment described herein as "exemplary" is not necessarily to be construed as superior to or better than other embodiments.

[0046] Furthermore, to better illustrate the present invention, numerous specific details are set forth in the following detailed embodiments. Those skilled in the art should understand that the present invention can be practiced without certain specific details. In other instances, methods, means, apparatus, and steps well known to those skilled in the art have not been described in detail in order to highlight the spirit of the present invention.

[0047] Unless otherwise stated, all units used in this specification are international standard units, and all numerical values ​​and ranges appearing in this invention should be understood to include systematic errors that are unavoidable in industrial production.

[0048] In this specification, the word "may" has two meanings: to perform a certain process and not to perform a certain process.

[0049] In this specification, references to "some specific / preferred embodiments," "other specific / preferred embodiments," "implementation," etc., refer to specific elements (e.g., features, structures, properties, and / or characteristics) related to that embodiment, which are included in at least one of the embodiments described herein and may or may not be present in other embodiments. Furthermore, it should be understood that these elements may be combined in any suitable manner in various embodiments.

[0050] In this specification, the range of values ​​referred to as "value A to value B" refers to the range including the endpoint values ​​A and B.

[0051] This invention provides a method for preparing a calcium-based absorbent, characterized by comprising the following steps:

[0052] Step 1) Calcine the calcium-based raw material to obtain a raw material containing calcium oxide;

[0053] Step 2) Mix the raw material containing calcium oxide with glycerol to obtain a mixture;

[0054] Step 3) The mixture is subjected to solvothermal modification to obtain a slurry;

[0055] Step 4) Calcine the slurry to obtain a calcium-based absorbent.

[0056] The calcium-based raw material is calcined to obtain a raw material containing calcium oxide, and the reaction involved is CaCO3→CaO+CO2↑. Preferably, the mass fraction of calcium carbonate in the calcium-based raw material is greater than 80wt%.

[0057] According to the preparation method of the present invention, in step 1), the calcium-based raw material is one or more of limestone, snail shell or seashell.

[0058] According to the preparation method of the present invention, in step 1), the particle size of the raw material containing calcium oxide is 20 μm to 2 mm.

[0059] According to the preparation method of the present invention, in step 1), the calcination temperature is 700℃~1100℃.

[0060] The glycerol is derived from crude glycerol, a byproduct of biodiesel production.

[0061] According to the preparation method of the present invention, in step 2), the content of the raw material containing calcium oxide is 2-5 wt% based on the total mass of the mixture.

[0062] Within a certain range of calcium oxide content in the raw materials, calcium-based absorbent materials can be effectively modified, ensuring that the resulting calcium-based absorbent maintains good absorption performance even after multiple cycles. Excessive calcium oxide content leads to incomplete dissolution, affecting the dynamic precipitation process and resulting in less alteration to the material's surface pore structure. Conversely, insufficient calcium oxide content results in the use of more glycerol, which, although recoverable, increases energy consumption.

[0063] Preferably, other substances, such as alkali metal hydroxides or acetates, such as one or more of sodium hydroxide or magnesium acetate, may be added to the mixture.

[0064] According to the preparation method of the present invention, in step 3), the temperature of the solvothermal modification is 120℃~200℃; the time is 10~20 hours. At room temperature and pressure, calcium oxide has low solubility in glycerol. However, in the solvothermal modification process of the present invention, calcium oxide can dissolve in glycerol and be fully modified (forming a complex), resulting in a calcium-based absorbent with a large specific surface area and abundant pores during the subsequent calcination process.

[0065] The temperature for solvothermal modification is 120℃~200℃, preferably 160℃~200℃. If the temperature is too low, the calcium oxide will not dissolve sufficiently, resulting in insufficient modification and insignificant effect; if the temperature is too high, the energy consumption will be greater and the cost will be higher.

[0066] The solvothermal modification time is 10–20 hours, preferably 12–20 hours. Too short a solvothermal modification time will result in insufficient modification and an unfavorable pore structure; too long a solvothermal modification time will result in poor physical properties of the absorbent, high energy consumption, and reduced effectiveness of the calcium-based absorbent.

[0067] According to the preparation method of the present invention, in step 4), the calcination temperature is 700℃~900℃.

[0068] This calcination temperature can completely burn away the glycerol residue on the surface, while preserving the porous structure.

[0069] The preparation method according to the present invention further includes the following steps:

[0070] Step 5) Grind and sieve the calcium-based absorbent to ensure that the particle size of the calcium-based absorbent does not exceed 0.3 mm.

[0071] The present invention also provides a calcium-based absorbent, which is a calcium-based absorbent obtained by the preparation method described in the present invention.

[0072] The present invention also provides the use of the calcium-based absorbent according to the present invention for absorbing carbon dioxide or sulfur dioxide.

[0073] Taking carbon dioxide absorption as an example, the calcium-based absorbent of this invention significantly improves carbon dioxide absorption capacity in multiple cycles, especially in readily available natural materials. For example, using snail shell calcium oxide as a natural material, the conversion rate is less than 5% after 40 cycles, while glycerol-modified calcium oxide can still maintain around 20% under optimal conditions. The calcium-based absorbent prepared using this invention exhibits excellent anti-sintering properties, maintaining a stable macroporous pore structure during high-temperature cycling. This structure effectively slows down high-temperature sintering, thereby maintaining its high adsorption activity and giving the calcium-based absorbent superior cyclic absorption characteristics.

[0074] Example

[0075] To make the objectives, technical solutions, and advantages of this invention clearer, the invention will be further described in detail below with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are merely illustrative and not intended to limit the invention. Furthermore, the technical features involved in the various embodiments of this invention described below can be combined with each other as long as they do not conflict with each other.

[0076] Example 1-1

[0077] Snail shells were used as calcium-based raw materials. The calcium-based raw materials were calcined at 900℃ for 2 hours to obtain raw materials containing calcium oxide. 1g of raw materials containing calcium oxide was mixed with 40ml of glycerol under stirring conditions to obtain a mixture. The mixture was subjected to solvothermal modification to obtain a slurry. The slurry was calcined to obtain calcium-based absorbent 1-1.

[0078] The specific conditions for solvothermal modification and calcination are shown in Table 1.

[0079] Examples 1-2

[0080] Using the same method as in Example 1-1, but with changes to the specific conditions of solvothermal modification and calcination, calcium-based absorbents 1-2 were obtained.

[0081] The specific conditions for solvothermal modification and calcination are shown in Table 1.

[0082] Examples 1-3

[0083] Using the same method as in Example 1-1, but with changes to the specific conditions of solvothermal modification and calcination, calcium-based absorbents 1-3 were obtained.

[0084] The specific conditions for solvothermal modification and calcination are shown in Table 1.

[0085] Table 1

[0086] Example Modification temperature / °C Modification time / h Calcination temperature / °C 1-1 160 12 850 1-2 160 16 850 1-3 160 20 850

[0087] Performance testing

[0088] Performance tests were conducted on calcium-based absorbents 1-1, 1-2, and 1-3 using a CO2 cyclic capture experiment in a thermogravimetric reactor: 1) The calcium-based absorbent was heated to 900℃ at a rate of 40℃ / min under N2 conditions and maintained for 5 min; 2) Subsequently, the temperature was lowered to 650℃ for carbon capture (CO2 concentration 15 vol.%, reaction time 15 min, CaO + CO2 → CaCO3); 3) Subsequently, the temperature was raised to 900℃ and maintained for 5 min for adsorbent regeneration (reaction time 2 min, CaCO3 → CaO + CO2↑); 4) Processes 2)-3) were repeated for 40 reaction cycles. Results are as follows: Figure 1 As shown.

[0089] Example 2-1

[0090] Snail shells were used as the calcium-based raw material. The calcium-based raw material was calcined at 900℃ for 2 hours to obtain a raw material containing calcium oxide. 1g of the raw material containing calcium oxide was mixed with 40ml of glycerol under stirring to obtain a mixture. The mixture was then subjected to solvothermal modification to obtain a slurry. The slurry was then calcined to obtain calcium-based absorbent 2-1.

[0091] The specific conditions for solvothermal modification and calcination are shown in Table 2.

[0092] Example 2-2

[0093] Using the same method as in Example 2-1, but with changes to the specific conditions of solvothermal modification and calcination, calcium-based absorbent 2-2 was obtained.

[0094] The specific conditions for solvothermal modification and calcination are shown in Table 2.

[0095] Example 2-3

[0096] Using the same method as in Example 2-1, but with changes to the specific conditions of solvothermal modification and calcination, calcium-based absorbent 2-3 was obtained.

[0097] The specific conditions for solvothermal modification and calcination are shown in Table 2.

[0098] Table 2

[0099] Example Modification temperature / °C Modification time / h Calcination temperature / °C 2-1 120 20 850 2-2 160 20 850 2-3 200 20 850

[0100] Performance testing

[0101] Performance tests were conducted on calcium-based absorbents 2-1, 2-2, and 2-3 using a CO2 cyclic capture experiment in a thermogravimetric reactor: 1) The calcium-based absorbent was heated to 900℃ at a rate of 40℃ / min under N2 conditions and maintained for 5 min; 2) Subsequently, the temperature was lowered to 650℃ for carbon capture (CO2 concentration 15 vol.%, reaction time 15 min, CaO + CO2 → CaCO3); 3) Subsequently, the temperature was raised to 900℃ and maintained for 5 min for adsorbent regeneration (reaction time 2 min, CaCO3 → CaO + CO2↑); 4) Processes 2)-3) were repeated for 40 reaction cycles. Results are as follows: Figure 2 As shown.

[0102] Example 3-1

[0103] Snail shells were used as the calcium-based raw material. The calcium-based raw material was calcined at 900℃ for 2 hours to obtain a raw material containing calcium oxide. 1g of the raw material containing calcium oxide was mixed with 40ml of glycerol under stirring conditions to obtain a mixture. The mixture was then subjected to solvothermal modification to obtain a slurry. The slurry was then calcined to obtain calcium-based absorbent 3-1.

[0104] The specific conditions for solvothermal modification and calcination are shown in Table 3.

[0105] Example 3-2

[0106] Using the same method as in Example 3-1, sodium hydroxide was added to the mixture, and the mixture was fed in a mass ratio of sodium hydroxide to raw material containing calcium oxide of 1:9 to obtain calcium-based absorbent 3-2.

[0107] The specific conditions for solvothermal modification, addition of substances, and calcination are shown in Table 3.

[0108] Example 3-3

[0109] Using the same method as in Example 3-1, magnesium acetate was added to the mixture, and the feed was added at a mass ratio of magnesium acetate to raw material containing calcium oxide of 1:9 to obtain calcium-based absorbent 3-3.

[0110] The specific conditions for solvothermal modification, addition of substances, and calcination are shown in Table 3.

[0111] Table 3

[0112] Example Modification temperature / °C Modification time / h Additives Calcination temperature / °C 3-1 160 20 none 850 3-2 160 20 Sodium hydroxide 850 3-3 160 20 Magnesium acetate 850

[0113] Performance testing

[0114] Performance tests were conducted on calcium-based absorbents 3-1, 3-2, and 3-3 using a CO2 cyclic capture experiment in a thermogravimetric reactor: 1) The calcium-based absorbent was heated to 900℃ at a rate of 40℃ / min under N2 conditions and maintained for 5 min; 2) Subsequently, the temperature was lowered to 650℃ for carbon capture (CO2 concentration 15 vol.%, reaction time 15 min, CaO + CO2 → CaCO3); 3) Subsequently, the temperature was raised to 900℃ and maintained for 5 min for adsorbent regeneration (reaction time 2 min, CaCO3 → CaO + CO2↑); 4) Processes 2)-3) were repeated for 40 reaction cycles. Results are as follows: Figure 3 As shown.

[0115] Example 4

[0116] A CO2 cyclic capture experiment was conducted using calcium-based absorbent 3-3 in a thermogravimetric reactor: 1) The calcium-based absorbent was heated to 900℃ at a rate of 40℃ / min under N2 conditions and maintained for 5 min; 2) Subsequently, the temperature was lowered to 650℃ for carbon capture (CO2 concentration of 15 vol.%, reaction time 15 min, CaO + CO2 → CaCO3); 3) Subsequently, the temperature was raised to 900℃ and maintained for 5 min for adsorbent regeneration (reaction time 2 min, CaCO3 → CaO + CO2↑); 4) Processes 2)-3) were repeated for 40 reaction cycles. SEM analysis was then performed, and the results are as follows: Figure 4 As shown.

[0117] Comparative Example 1

[0118] A raw material containing calcium oxide was obtained by calcining the natural material snail shells at 900℃ for 2 hours, and it is denoted as calcium-based absorbent-p-1.

[0119] A CO2 cyclic capture experiment was conducted in a thermogravimetric reactor: 1) The calcium-based absorbent was heated to 900℃ at a rate of 40℃ / min under N2 conditions and maintained for 5 min; 2) Subsequently, the temperature was lowered to 650℃ for carbon capture (CO2 concentration of 15 vol.%, reaction time 15 min, CaO + CO2 → CaCO3); 3) Subsequently, the temperature was raised to 900℃ and maintained for 5 min for adsorbent regeneration (reaction time 2 min, CaCO3 → CaO + CO2↑); 4) Processes 2)-3) were repeated for 40 reaction cycles. SEM analysis was then performed, and the results are as follows: Figure 5 As shown.

[0120] like Figure 4 As shown, the calcium-based absorbent 3-3 possesses a rich pore structure and maintains a macroporous stable pore structure during high-temperature cyclic reactions. This structure effectively slows down high-temperature sintering, thereby maintaining high adsorption activity and giving the calcium-based absorbent superior cyclic absorption characteristics. In addition... Figure 5 Among them, calcium-based absorbent-1 has a smoother surface, less porosity, and weaker CO2 capture activity.

Claims

1. A calcium-based absorbent used for absorbing carbon dioxide, characterized in that, The preparation method of the calcium-based absorbent includes the following steps: Step 1) Calcine the calcium-based raw material to obtain a raw material containing calcium oxide; Step 2) Mix the raw material containing calcium oxide with glycerol to obtain a mixture; Step 3) The mixture is subjected to solvothermal modification to obtain a slurry; Step 4) Calcine the slurry to obtain a calcium-based absorbent; in, In step 1), the particle size of the raw material containing calcium oxide is 20 μm to 2 mm; In step 3), the temperature of the solvothermal modification is 160℃~200℃; the time is 10~20 hours.

2. The use according to claim 1, wherein, In step 1), the calcium-based raw material is one or more of limestone, snail shells, or seashells.

3. The use according to claim 1 or 2, wherein, In step 1), the calcination temperature is 700℃~1100℃.

4. The use according to claim 1 or 2, wherein, In step 2), the content of the raw material containing calcium oxide is 2-5 wt% based on the total mass of the mixture.

5. The use according to claim 1 or 2, wherein, In step 4), the calcination temperature is 700℃~900℃.

6. The use according to claim 1 or 2, characterized in that, The preparation method of the calcium-based absorbent further includes the following steps: Step 5) Grind and sieve the calcium-based absorbent to ensure that the particle size of the calcium-based absorbent does not exceed 0.3 mm.

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