Modified calcium-based absorbent for capturing carbon dioxide and preparation method of modified calcium-based absorbent

Abstract

The invention discloses a modified calcium-based absorbent for capturing carbon dioxide and a preparation method thereof.The method comprises the following steps that S1, natural limestone powder, attapulgite, montmorillonite powder and a binder are added into a solvent to be evenly stirred, and turbid liquid is obtained; s2, stirring under heating, and drying to obtain a solid mixture; and S3, calcining in an inert gas atmosphere, and grinding to obtain the modified calcium-based absorbent. According to the invention, the attapulgite and montmorillonite are adopted for composite modification of the calcium-based absorbent, through the unique layered structure and surface characteristics of minerals, the problem of sintering agglomeration of CaO particles in high-temperature circulation is effectively inhibited, and the technical bottleneck of fast activity attenuation of a traditional calcium-based material is overcome. Compared with an existing modification technology, the preparation method has the advantages of being simple in preparation process and low in cost, meanwhile, the cycle stability and the CO2 adsorption capacity of the absorbent are remarkably improved, and a reliable solution is provided for industrial application of the calcium-based CO2 trapping material.

Description

Technical Field

[0001] The present invention relates to the technical field of CO2 capture, and in particular to a modified calcium-based absorbent for capturing carbon dioxide and a preparation method thereof. Background Art

[0002] The cement industry, a vital global foundational materials industry, not only supports infrastructure development but is also a major source of carbon emissions. According to statistics, CO2 generated by carbonate decomposition and fuel combustion during cement production accounts for approximately 8% of total global anthropogenic emissions, placing increasing pressure on emissions reduction. The calcium-based absorbent cyclic calcination method is considered one of the most promising carbon capture technologies in the cement industry due to its wide raw material availability, low cost, and ability to be co-processed with cement production processes. This technology utilizes the reversible reaction of calcium oxide with CO2 to achieve efficient capture at 600-700°C. The absorbed product, calcium carbonate, can then be recycled as a cement raw material, creating a closed-loop industrial process. However, traditional calcium-based materials experience sintering and pore structure collapse after repeated cycles, leading to a sharp decrease in reactivity and severely restricting their industrial application.

[0003] Currently, researchers have tried a variety of modification methods to improve the cyclic performance of calcium-based absorbents, including inert carrier doping (such as Al2O3, SiO2, MgO, etc.), alkali metal salt modification (such as K2CO3, Na2CO3), and the construction of new composite materials (such as CaO-CaZrO3). Inert carrier doping (such as Al2O3) can form high melting point calcium aluminates (such as Ca12Al 14 O 33 ) inhibits CaO grain sintering, but excessive doping may reduce the active CaO content and weaken CO2 adsorption capacity. Alkali metal salt modification (such as K2CO3) can reduce the carbonation reaction temperature and improve reaction kinetics, but it is volatile at high temperatures and may cause absorbent agglomeration. Composite materials such as calcium aluminum oxide have good stability, but the synthesis process is complex and costly, making it difficult to apply on a large scale.

[0004] In addition, in recent years, some new modification strategies, such as core-shell structure design, nano-confined loading, and bio-templated synthesis of porous CaO, have also shown certain potential. For example, the CaO@SiO2 core-shell structure prepared by the sol-gel method can effectively reduce the contact between CaO particles and inhibit sintering, but its shell may hinder the diffusion of CO2, resulting in a decrease in the reaction rate. Nano-confined loading (such as embedding CaO into the mesoporous molecular sieve SBA-15) can significantly improve the cyclic stability, but the preparation cost of nanomaterials is high, and large-scale synthesis still faces challenges. Bio-templated methods (such as using biomass-derived porous carbon to load CaO) can provide rich pore structures, but carbon-based materials are easily ablated in high-temperature oxidizing environments, affecting long-term stability.

[0005] Therefore, it is necessary to improve the existing technology to provide a more reliable solution. Summary of the Invention

[0006] The technical problem to be solved by the present invention is to provide a modified calcium-based absorbent for capturing carbon dioxide and a preparation method thereof in view of the deficiencies in the above-mentioned prior art.

[0007] To solve the above technical problems, the technical solution adopted by the present invention is: a method for preparing a modified calcium-based absorbent for capturing carbon dioxide, comprising the following steps:

[0008] S1, mixing natural limestone powder, attapulgite, montmorillonite powder and a binder, adding the resulting mixture to a solvent, and stirring to obtain a suspension;

[0009] S2, stirring the suspension under heating, and then drying to obtain a solid mixture;

[0010] S3. calcining the solid mixture in an inert gas atmosphere and grinding it to obtain a modified calcium-based absorbent.

[0011] Preferably, the binder is aluminum phosphate and the solvent is water.

[0012] Preferably, in step S1, the added amounts of attapulgite powder, montmorillonite powder and binder are 5-15%, 5-15% and 0.5-5% of the mass of the natural limestone powder, respectively.

[0013] Preferably, in step S2, the heating and stirring temperature is 40-60°C for 0.5-4 hours, and the drying temperature is 90-110°C for 3-12 hours.

[0014] Preferably, the inert gas in step S3 is nitrogen or argon, the calcination temperature is 800-950° C., the calcination time is 1-4 hours, and the calcined product is ground to less than 0.1-0.3 mm.

[0015] Preferably, the method for preparing the modified calcium-based absorbent for capturing carbon dioxide comprises the following steps:

[0016] S1, natural limestone powder, attapulgite, montmorillonite powder and binder are mixed uniformly, the resulting mixture is added to water, and stirred uniformly at 100-400r / min to obtain a suspension;

[0017] The added amounts of attapulgite, montmorillonite powder and binder are 5-15%, 5-15% and 0.5-5% of the mass of natural limestone powder respectively, and the mass of water is 0.5-5 times of that of natural limestone powder.

[0018] S2. Stir the suspension at 40-60° C. for 0.5-4 h, and dry at 90-110° C. for 3-12 h to obtain a solid mixture;

[0019] S3. calcining the solid mixture at 800-950° C. for 1-4 h in a nitrogen atmosphere, cooling it to room temperature, and then grinding it to a thickness of less than 0.1-0.3 mm to obtain a modified calcium-based absorbent.

[0020] Preferably, the method for preparing the modified calcium-based absorbent for capturing carbon dioxide comprises the following steps:

[0021] S1, mixing natural limestone powder, attapulgite, montmorillonite powder and aluminum phosphate binder, adding the resulting mixture into water, and stirring at 200 r / min to obtain a suspension;

[0022] The addition amounts of attapulgite, montmorillonite powder and aluminum phosphate binder are 5%, 5% and 2% of the mass of natural limestone powder respectively, and the mass of water is 2 times of that of natural limestone powder.

[0023] S2, stirring the suspension at 50°C for 1 h, and drying at 105°C for 6 h to obtain a solid mixture;

[0024] S3. The solid mixture was calcined at 800° C. for 2 h in a nitrogen atmosphere, cooled to room temperature, and then ground and passed through a 0.15 mm sieve. The sieved product was collected to obtain a modified calcium-based absorbent.

[0025] Preferably, the method for preparing the modified calcium-based absorbent for capturing carbon dioxide comprises the following steps:

[0026] S1, mixing natural limestone powder, attapulgite, montmorillonite powder and aluminum phosphate binder, adding the resulting mixture into water, and stirring at 200 r / min to obtain a suspension;

[0027] The addition amounts of attapulgite, montmorillonite powder and aluminum phosphate binder are 10%, 10% and 2% of the mass of natural limestone powder respectively, and the mass of water is 2 times of that of natural limestone powder.

[0028] S2, stirring the suspension at 50°C for 1 h, and drying at 105°C for 6 h to obtain a solid mixture;

[0029] S3. The solid mixture was calcined at 850° C. for 2 h in a nitrogen atmosphere, cooled to room temperature, and then ground and passed through a 0.15 mm sieve. The sieved product was collected to obtain a modified calcium-based absorbent.

[0030] Preferably, the method for preparing the modified calcium-based absorbent for capturing carbon dioxide comprises the following steps:

[0031] S1, mixing natural limestone powder, attapulgite, montmorillonite powder and aluminum phosphate binder, adding the resulting mixture into water, and stirring at 200 r / min to obtain a suspension;

[0032] The addition amounts of attapulgite, montmorillonite powder and aluminum phosphate binder are 15%, 15% and 2% of the mass of natural limestone powder respectively, and the mass of water is 2 times of that of natural limestone powder.

[0033] S2, stirring the suspension at 50°C for 1 h, and drying at 105°C for 6 h to obtain a solid mixture;

[0034] S3. The solid mixture was calcined at 900° C. for 2 h in a nitrogen atmosphere, cooled to room temperature, and then ground and passed through a 0.15 mm sieve. The sieved product was collected to obtain a modified calcium-based absorbent.

[0035] The present invention also provides a modified calcium-based absorbent for capturing carbon dioxide, which is prepared by the method described above.

[0036] The beneficial effects of the present invention are:

[0037] This invention provides a modified calcium-based absorbent for capturing carbon dioxide and a method for its preparation. This composite modified calcium-based absorbent, made of attapulgite and montmorillonite, effectively suppresses the sintering and agglomeration of CaO particles during high-temperature cycling through the minerals' unique layered structure and surface properties, overcoming the technical bottleneck of rapid activity decay in traditional calcium-based materials. Compared to existing modification technologies, this invention offers the advantages of a simpler preparation process and lower costs. It also significantly improves the absorbent's cyclic stability and CO2 adsorption capacity, providing a reliable solution for the industrial application of calcium-based CO2 capture materials. BRIEF DESCRIPTION OF THE DRAWINGS

[0038] Figure 1 The carbonation conversion rate X of the calcium-based absorbent prepared in the examples and comparative examples is N Curves changing with cycle number. DETAILED DESCRIPTION

[0039] The present invention is further described in detail below with reference to the embodiments so that those skilled in the art can implement the invention with reference to the description.

[0040] It should be understood that terms such as “having”, “including” and “comprising” used herein do not preclude the existence or addition of one or more other elements or combinations thereof.

[0041] Unless otherwise specified, the experimental methods used in the following examples are conventional methods. Materials and reagents used in the following examples are commercially available unless otherwise specified. In the following examples, where specific conditions are not specified, the experiments were conducted under conventional conditions or those recommended by the manufacturer. Reagents and instruments used, where the manufacturer is not specified, are commercially available conventional products.

[0042] The present invention provides a modified calcium-based absorbent for capturing carbon dioxide and a preparation method thereof. The modified calcium-based absorbent is prepared by a wet process using natural limestone as the calcium-based absorbent, attapulgite and montmorillonite as modifying additives, and aluminum phosphate as a binder. The method comprises the following steps:

[0043] S1, mixing natural limestone powder, attapulgite, montmorillonite powder and a binder, adding the resulting mixture to a solvent, and stirring to obtain a suspension;

[0044] S2, stirring the suspension under heating, and then drying to obtain a solid mixture;

[0045] S3. calcining the solid mixture in an inert gas atmosphere and grinding it to obtain a modified calcium-based absorbent.

[0046] In a preferred embodiment, the binder is aluminum phosphate and the solvent is water.

[0047] In a preferred embodiment, in step S1, the added amounts of attapulgite powder, montmorillonite powder and binder are 5-15%, 5-15% and 0.5-5% of the mass of the natural limestone powder, respectively.

[0048] In a preferred embodiment, in step S2, the heating and stirring temperature is 40-60°C for 0.5-4 hours, and the drying temperature is 90-110°C for 3-12 hours.

[0049] In a preferred embodiment, the inert gas in step S3 is nitrogen or argon, the calcination temperature is 800-950° C., the calcination time is 1-4 hours, and the calcined product is ground to less than 0.1-0.3 mm.

[0050] In a preferred embodiment, the method for preparing a modified calcium-based absorbent for capturing carbon dioxide comprises the following steps:

[0051] S1, natural limestone powder, attapulgite, montmorillonite powder and binder are mixed uniformly, the resulting mixture is added to water, and stirred uniformly at 100-400r / min to obtain a suspension;

[0052] The added amounts of attapulgite, montmorillonite powder and binder are 5-15%, 5-15% and 0.5-5% of the mass of natural limestone powder respectively, and the mass of water is 0.5-5 times of that of natural limestone powder.

[0053] S2. Stir the suspension at 40-60° C. for 0.5-4 h, and dry at 90-110° C. for 3-12 h to obtain a solid mixture;

[0054] S3. Calcining the solid mixture at 800-950°C for 1-4 hours in a nitrogen atmosphere, cooling to room temperature, and then grinding to a particle size of less than 0.1-0.3 mm to obtain a modified calcium-based absorbent. To ensure sample stability, the prepared modified absorbent must be stored in a sealed reagent bottle to avoid exposure to water vapor and CO2 in the air to prevent deterioration.

[0055] Attapulgite and montmorillonite, as natural mineral modifiers, can significantly improve the cyclic stability of calcium-based CO₂ absorbers. Their unique layered structure and abundant porosity effectively disperse CaO particles, inhibiting activity decay caused by high-temperature sintering. Attapulgite's nanofibrous structure provides excellent mechanical support, while montmorillonite's cation exchange properties help stabilize CaO dispersion. Compared to synthetic supports, these natural minerals offer the advantages of readily available raw materials and low cost, enabling performance enhancements through simple composite processes. The active sites in the minerals also promote CO₂ diffusion and adsorption, extending the material's service life while maintaining high reactivity. This natural mineral-based modification strategy provides new insights into the development of efficient and economical calcium-based CO₂ capture materials.

[0056] The above is the overall concept of the present invention. Detailed examples and comparative examples are provided below to further illustrate the present invention.

[0057] 1. Sources of the main raw materials in the following examples and comparative examples:

[0058] Natural limestone was sourced from a limestone plant in Henan Province (100-mesh particle size), attapulgite was sourced from a mining company in Jiangsu Province (100-mesh particle size), and montmorillonite was sourced from a materials company in Guangzhou Province (100-mesh particle size). Their chemical compositions were analyzed using X-ray fluorescence spectrometry (XRF), as shown in Tables 1-3 below. Aluminum phosphate was of analytical grade.

[0059] Table 1 Chemical composition analysis of limestone (wt.%)

[0060]

[0061] Table 2 Chemical composition analysis of attapulgite (wt.%)

[0062]

[0063] Table 3 Chemical composition analysis of montmorillonite (wt.%)

[0064]

[0065] Note: Loss is loss on ignition

[0066] 2. The following cyclic calcination / carbonation performance test and evaluation methods are as follows:

[0067] This experiment uses a tubular furnace system to study the cyclic calcination / carbonation performance of attapulgite / montmorillonite modified calcium-based absorbent. The experimental system mainly consists of a high-temperature tubular furnace, a quartz reaction tube, an electronic balance (accuracy 0.1 mg), a mass flow controller, a quartz sample boat, a flue gas analyzer and a data acquisition system. Before the experiment, the system air tightness is first checked. After confirming that there is no leakage in the pipeline, the reactor is purged with 100% N2 at a flow rate of 100 mL / min for 40 minutes to eliminate air interference. 300 mg of the modified sample is evenly spread in a quartz boat and placed in the constant temperature zone of the tubular furnace. During the experiment, the calcination stage was set to rise to 800-950°C at a heating rate of 10°C / min, maintained at 100% N2 atmosphere (100mL / min) for 10 minutes, then cooled to 50°C at a cooling rate of 10°C / min, and kept in a pure nitrogen protective atmosphere for 20 minutes to cool the sample to room temperature before taking it out and weighing; the carbonation stage was raised to 650-750°C at a heating rate of 10°C / min, switched to 20% CO2+80% N2 (volume ratio) mixed gas (total flow 100mL / min) and reacted for 20 minutes, then cooled to 50°C at 10°C / min and maintained under pure nitrogen protection for 20 minutes before taking it out and weighing. The complete operation cycle of this calcination-carbonation was repeated 20 times, and the experiment maintained a constant heating / cooling rate of 10°C / min throughout the whole process. Carbonation conversion rate (X N ) is calculated as follows:

[0068]

[0069] Where:

[0070] X N is the carbonation rate after the Nth cycle;

[0071] m car is the mass of the absorbent after the Nth carbonation;

[0072] m cal is the mass of the absorbent after calcination;

[0073] m0 is the initial mass of the absorbent;

[0074] α is the percentage of CaO in the absorbent;

[0075] M CaO and M CO2 are the molar masses of CaO and CO2, respectively.

[0076] Example 1

[0077] A modified calcium-based absorbent for capturing carbon dioxide, the preparation method of which comprises the following steps:

[0078] S1, natural limestone powder (10g), attapulgite, montmorillonite powder and aluminum phosphate binder were mixed uniformly, the resulting mixture was added to water, and stirred at 200r / min to obtain a suspension;

[0079] The addition amounts of attapulgite, montmorillonite powder and aluminum phosphate binder are 5%, 5% and 2% of the mass of natural limestone powder respectively, and the mass of water is 2 times of that of natural limestone powder.

[0080] S2, stirring the suspension at 50°C for 1 h, and drying at 105°C for 6 h to obtain a solid mixture;

[0081] S3. The solid mixture was calcined at 800° C. for 2 h in a nitrogen atmosphere, cooled to room temperature, and then ground and passed through a 0.15 mm sieve. The sieved product was collected to obtain a modified calcium-based absorbent, which was recorded as C1.

[0082] During the experiment, 300 mg of sample was taken for 20 cycle tests. The calcination stage was 800°C and 100% N2 for 10 minutes, and the carbonation stage was 650°C and 20% CO2 + 80% N2 (volume ratio) for 20 minutes. The temperature was increased and decreased at a rate of 10°C / min in each stage. After the reaction, the temperature was cooled to 50°C and weighed under nitrogen protection.

[0083] Example 2

[0084] A modified calcium-based absorbent for capturing carbon dioxide, the preparation method of which comprises the following steps:

[0085] S1, mixing natural limestone powder, attapulgite, montmorillonite powder and aluminum phosphate binder, adding the resulting mixture into water, and stirring at 200 r / min to obtain a suspension;

[0086] The addition amounts of attapulgite, montmorillonite powder and aluminum phosphate binder are 10%, 10% and 2% of the mass of natural limestone powder respectively, and the mass of water is 2 times of that of natural limestone powder.

[0087] S2, stirring the suspension at 50°C for 1 h, and drying at 105°C for 6 h to obtain a solid mixture;

[0088] S3. The solid mixture was calcined at 850°C for 2 hours in a nitrogen atmosphere, cooled to room temperature, ground, and passed through a 0.15 mm sieve. The product was collected and sieved to obtain a modified calcium-based absorbent, designated as C2. During the experiment, 300 mg of the sample was tested for 20 cycles. The calcination stage was 850°C and 100% N2 for 10 minutes, and the carbonation stage was 700°C and 20% CO2 + 80% N2 (volume ratio) for 20 minutes. The temperature was increased and decreased at a rate of 10°C / min in each stage. After the reaction, the temperature was cooled to 50°C under nitrogen protection and weighed.

[0089] Example 3

[0090] A modified calcium-based absorbent for capturing carbon dioxide, the preparation method of which comprises the following steps:

[0091] S1, mixing natural limestone powder, attapulgite, montmorillonite powder and aluminum phosphate binder, adding the resulting mixture into water, and stirring at 200 r / min to obtain a suspension;

[0092] The addition amounts of attapulgite, montmorillonite powder and aluminum phosphate binder are 15%, 15% and 2% of the mass of natural limestone powder respectively, and the mass of water is 2 times of that of natural limestone powder.

[0093] S2, stirring the suspension at 50°C for 1 h, and drying at 105°C for 6 h to obtain a solid mixture;

[0094] S3. The solid mixture was calcined at 900°C for 2 hours in a nitrogen atmosphere, cooled to room temperature, ground and passed through a 0.15 mm sieve, and the sieved product was collected to obtain a modified calcium-based absorbent, which was recorded as C3. During the experiment, 300 mg of the sample was taken and subjected to 20 cycles of testing. The calcination stage was 900°C and 100% N2 for 10 minutes, and the carbonation stage was 750°C and 20% CO2 + 80% N2 (volume ratio) for 20 minutes. The temperature was increased and decreased at a rate of 10°C / min in each stage. After the reaction, the temperature was cooled to 50°C under nitrogen protection and weighed.

[0095] Comparative Example 1

[0096] A calcium-based absorbent for capturing carbon dioxide, the preparation method of which comprises the following steps:

[0097] S1. Take 10 g of natural limestone powder, without adding any modifier, add 2% by weight of aluminum phosphate binder, add the resulting mixture to water, and stir at 200 rpm to obtain a suspension;

[0098] S2, stirring the suspension at 50°C for 1 h, and drying at 105°C for 6 h to obtain a solid mixture;

[0099] S3. The mixture was stirred with deionized water at 200 rpm at a constant temperature of 50°C to form a suspension. The suspension was dried at 105°C for 6 hours and then ground. The unmodified calcium-based absorbent was calcined at 800°C in a 100% N2 atmosphere for 2 hours to obtain C0. During the experiment, 300 mg of the sample was tested for 20 cycles. The calcination stage was 800°C in 100% N2 for 10 minutes, and the carbonation stage was 650°C in 20% CO2 + 80% N2 for 20 minutes. The temperature was increased and decreased at a rate of 10°C / min in each stage. After the reaction, the temperature was cooled to 50°C under nitrogen protection and weighed.

[0100] Performance Testing

[0101] 1. Carbonation conversion rate X of the absorbent prepared in the examples and comparative examples N As the number of cycles changes, Figure 1 As shown, it can be seen that Examples 1-3 have excellent CO2 absorption capacity and can maintain a high CO2 adsorption rate after multiple cycles. The CO2 absorption capacity and cycle stability in Comparative Example 1 are significantly worse than those of the examples.

[0102] 2. The specific surface area and specific pore volume comparison of the absorbents prepared in the examples and comparative examples are shown in Table 4:

[0103] Table 4

[0104]

[0105]

[0106] From the results in the above table, it can be seen that the initial specific surface area and specific pore volume of the absorbent prepared in Examples 1-3 are significantly higher than those in Comparative Example 1, and after 20 cycles, Examples 1-3 are still able to maintain relatively high specific surface area and specific pore volume, which are significantly better than Comparative Example 1 in terms of indicators.

[0107] Although the embodiments of the present invention have been disclosed above, they are not limited to the applications listed in the description and implementation methods. They can be fully applied to various fields suitable for the present invention. For those familiar with the art, additional modifications can be easily implemented. Therefore, without departing from the general concept defined by the claims and the scope of equivalents, the present invention is not limited to specific details.

Claims

1. A method for preparing a modified calcium-based absorbent for capturing carbon dioxide, characterized in that: The following steps are involved: S1, mixing natural limestone powder, attapulgite, montmorillonite powder and a binder, adding the resulting mixture to a solvent, and stirring to obtain a suspension; S2, stirring the suspension under heating, and then drying to obtain a solid mixture; S3. calcining the solid mixture in an inert gas atmosphere and grinding it to obtain a modified calcium-based absorbent.

2. The method for preparing a modified calcium-based absorbent for capturing carbon dioxide according to claim 1, wherein: in, The binder is aluminum phosphate, and the solvent is water.

3. The method for preparing a modified calcium-based absorbent for capturing carbon dioxide according to claim 2, wherein: In step S1, the added amounts of the attapulgite powder, montmorillonite powder and binder are 5-15%, 5-15% and 0.5-5% of the mass of the natural limestone powder respectively.

4. The method for preparing a modified calcium-based absorbent for capturing carbon dioxide according to claim 3, wherein: In step S2, the heating and stirring temperature is 40-60°C for 0.5-4 hours, and the drying temperature is 90-110°C for 3-12 hours.

5. The method for preparing a modified calcium-based absorbent for capturing carbon dioxide according to claim 4, characterized in that: The inert gas in step S3 is nitrogen or argon, the calcination temperature is 800-950° C., the calcination time is 1-4 hours, and the calcined product is ground to less than 0.1-0.3 mm.

6. The method for preparing a modified calcium-based absorbent for capturing carbon dioxide according to claim 1, wherein: The following steps are involved: S1, natural limestone powder, attapulgite, montmorillonite powder and binder are mixed uniformly, the resulting mixture is added to water, and stirred uniformly at 100-400r / min to obtain a suspension; The added amounts of attapulgite, montmorillonite powder and binder are 5-15%, 5-15% and 0.5-5% of the mass of natural limestone powder respectively, and the mass of water is 0.5-5 times of that of natural limestone powder. S2. Stir the suspension at 40-60° C. for 0.5-4 h, and dry at 90-110° C. for 3-12 h to obtain a solid mixture; S3. calcining the solid mixture at 800-950° C. for 1-4 h in a nitrogen atmosphere, cooling it to room temperature, and then grinding it to a thickness of less than 0.1-0.3 mm to obtain a modified calcium-based absorbent.

7. The method for preparing a modified calcium-based absorbent for capturing carbon dioxide according to claim 6, characterized in that: The following steps are involved: S1, mixing natural limestone powder, attapulgite, montmorillonite powder and aluminum phosphate binder, adding the resulting mixture into water, and stirring at 200 r / min to obtain a suspension; The addition amounts of attapulgite, montmorillonite powder and aluminum phosphate binder are 5%, 5% and 2% of the mass of natural limestone powder respectively, and the mass of water is 2 times of that of natural limestone powder. S2, stirring the suspension at 50°C for 1 h, and drying at 105°C for 6 h to obtain a solid mixture; S3. The solid mixture was calcined at 800° C. for 2 h in a nitrogen atmosphere, cooled to room temperature, and then ground and passed through a 0.15 mm sieve. The sieved product was collected to obtain a modified calcium-based absorbent.

8. The method for preparing a modified calcium-based absorbent for capturing carbon dioxide according to claim 6, wherein: The following steps are involved: S1, mixing natural limestone powder, attapulgite, montmorillonite powder and aluminum phosphate binder, adding the resulting mixture into water, and stirring at 200 r / min to obtain a suspension; The addition amounts of attapulgite, montmorillonite powder and aluminum phosphate binder are 10%, 10% and 2% of the mass of natural limestone powder respectively, and the mass of water is 2 times of that of natural limestone powder. S2, stirring the suspension at 50°C for 1 h, and drying at 105°C for 6 h to obtain a solid mixture; S3. The solid mixture was calcined at 850° C. for 2 h in a nitrogen atmosphere, cooled to room temperature, and then ground and passed through a 0.15 mm sieve. The sieved product was collected to obtain a modified calcium-based absorbent.

9. The method for preparing a modified calcium-based absorbent for capturing carbon dioxide according to claim 6, wherein: The following steps are involved: S1, mixing natural limestone powder, attapulgite, montmorillonite powder and aluminum phosphate binder, adding the resulting mixture into water, and stirring at 200 r / min to obtain a suspension; The addition amounts of attapulgite, montmorillonite powder and aluminum phosphate binder are 15%, 15% and 2% of the mass of natural limestone powder respectively, and the mass of water is 2 times of that of natural limestone powder. S2, stirring the suspension at 50°C for 1 h, and drying at 105°C for 6 h to obtain a solid mixture; S3. The solid mixture was calcined at 900° C. for 2 h in a nitrogen atmosphere, cooled to room temperature, and then ground and passed through a 0.15 mm sieve. The sieved product was collected to obtain a modified calcium-based absorbent.

10. A modified calcium-based absorbent for capturing carbon dioxide, characterized in that: It is prepared by the method according to any one of claims 1 to 9.

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