Preparation method of calcium-based absorbent, calcium-based absorbent and application of calcium-based absorbent

Abstract

The invention relates to a preparation method of a calcium-based absorbent, the calcium-based absorbent and application of the calcium-based absorbent. The preparation method of the calcium-based absorbent comprises the following steps: 1) calcining a calcium-based raw material to obtain a raw material containing calcium oxide; 2) mixing the raw material containing calcium oxide with glycerol to obtain a mixture; 3) performing solvothermal modification on the mixture to obtain slurry; and 4) calcining the slurry to obtain the calcium-based absorbent. The calcium-based absorbent with the loose structure is prepared, the preparation process is simple, raw materials are cheap, and the calcium-based absorbent can be applied to large-scale production. The calcium-based absorbent disclosed by the invention has the advantages of high cycle conversion rate, stable pore structure, difficulty in sintering and inactivation, high efficiency, excellent performance, good pollutant treatment effect and the like, and can still keep good gas absorption capacity even if carbon dioxide and sulfur dioxide are circularly absorbed for multiple times.

Description

Technical Field

[0001] The invention relates to a preparation method of a calcium-based absorbent, the calcium-based absorbent and application thereof, and belongs to the technical field of environmental pollution prevention and control and clean combustion. Background Art

[0002] CO2 capture, utilization and storage (CCS) technology is considered one of the most promising emission reduction technologies. This technology is to capture CO2 from large fixed carbon emission sources such as coal-fired power plants and cement plants, and then compress and transport high-concentration CO2 to chemical plants for utilization or geological storage to control CO2 emissions.

[0003] At the same time, coal-fired and biomass-fired boilers also produce a large amount of SO2 and other pollutants in the process of generating electricity. Among them, biomass-fired boilers generate electricity or produce steam, which has the advantages of being cleaner and more sustainable than coal-fired boilers. However, with the continuous increase in current environmental pressures, although the sulfur and ash content of biomass itself is low (compared to coal), considering the lower calorific value of biomass fuel, the converted sulfur and nitrogen emissions per unit calorific value do not have an advantage. Especially with the introduction of the concept of ultra-low emissions in China, sulfur and nitrogen emissions during the combustion of biomass fuels cannot be ignored.

[0004] The technology of capturing carbon dioxide based on calcium cycle is considered to be one of the most promising technologies for capturing CO2 after combustion. It can be directly applied to conventional coal-fired power plants, cement plants and steel plants. The principle is: flue gas containing 15-40% CO2 concentration is passed into the carbonation reactor, and the calcium oxide-based absorbent absorbs CO2. Then the generated carbonation product is transported to another calcination reactor with a higher temperature through a serial fluidized bed system, and the calcium oxide absorbent is regenerated. At the same time, a high concentration of CO2 is obtained for compression, transportation and final geological storage; and the regenerated calcium oxide absorbent is transported back to the carbonation reactor for capturing flue gas CO2. This technology has multiple advantages: 1. The absorbent precursor is abundant in nature and low in price; 2. It has superior chemical reaction kinetics in theory; 3. It has a relatively high CO2 absorption capacity in theory and can be recycled; 4. There is no need to reorganize the existing boiler unit; 5. The technology is low in cost and has good commercial application prospects; 6. The method is environmentally friendly and will not produce any secondary pollution. Based on the calcium cycle capture CO2 technology, the reaction formula is, in the carbonation reactor, CaO+CO2→CaCO3; in the calcination reactor, CaCO3→CaO+CO2↑. In addition, the technology of capturing SO2 in flue gas based on calcium-based absorbents is also widely used in power plant desulfurization and other environments, effectively absorbing SO2 gas that causes environmental pollution, and the reaction formula is CaO+SO2→CaSO3.

[0005] However, natural calcium-based absorbents have poor reactivity in the process of capturing carbon dioxide and sulfur dioxide, low conversion rates in actual use, and high energy consumption in the production process. In order to improve the reactivity of calcium-based absorbents, scholars have conducted a series of explorations, but materials with good performance often have high preparation costs, and simple modification treatments make it difficult to achieve high-efficiency capture of carbon dioxide / sulfur dioxide pollutants.

[0006] Various modification methods in existing studies have different effects on improving the reactivity and cyclic stability of calcium-based absorbents, but they all have certain problems and defects. For example, the cost of the absorbent has not been significantly reduced, or the preparation cycle of the absorbent is long, the process is complicated, and some even produce secondary pollution. Organic acid modification has recently been considered as one of the promising methods for modifying calcium-based absorbents. It generates organic acid calcium or calcium-based complexes through the reaction of organic acids with calcium-based absorbents. After a simple heat treatment, the organic acid functional groups of these organic acid calcium or complexes are rapidly decomposed to form modified calcium-based absorbents with developed pore structures and loose tissues.

[0007] The organic acid modification methods reported so far have their own advantages and disadvantages. The results of these literature surveys are preliminarily classified according to the technical methods and listed as follows:

[0008] (1) Wu et al.[1] A method for modifying a calcium-based absorbent with ethanol is disclosed, which reduces the decay rate of the carbonation conversion rate to a certain extent. However, CaO or CaCO3 itself does not react with ethanol, nor is it soluble in ethanol, and the interaction is small, and the final carbon capture capacity is not improved enough.

[0009] (2) Imani et al. [2] A method for modifying CaCO3 particles with acetic acid is disclosed. The conversion rate and porosity are increased, but the problem of high price and high cost has not been solved, and the process is relatively complicated.

[0010] (3)Sun et al. [3] Disclosed is a method for modifying a calcium-based absorbent with propionic acid. The propionic acid modification improves the CO2 capture activity and sulfation reaction activity of the calcium-based absorbent. The formed 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 an adsorbent from cellulose pyrolysis tar is disclosed, which can significantly improve the anti-sintering performance, but the process is complicated, difficult to implement, and cannot be recycled.

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

[0013] It can be seen that organic acid modification can improve the carbonation (capture CO2) and sulfation (capture SO2) reaction activity of calcium-based absorbents to a certain extent, but the preparation cost of the absorbent is still high, and the simple modification methods reported in the literature have not yet achieved the ideal CO2 capture and SO2 capture efficiency. The development of high-performance and low-cost absorbents for the capture of carbon dioxide and sulfur dioxide is still 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] Problem that the invention aims to solve

[0021] In order to solve the technical problems existing in the prior art, the present invention provides a preparation method of a calcium-based absorbent, a calcium-based absorbent and its use. The preparation method of the calcium-based absorbent of the present invention can prepare a calcium-based absorbent with uniform structure, can recycle a large amount of industrial crude glycerol (the largest byproduct in the production process of biodiesel), is environmentally friendly, low-cost, and can significantly modify the calcium-based absorbent, so that the calcium-based absorbent is not easy to sinter and inactivate, and can be used for multiple cycles of absorption.

[0022] Solutions for solving problems

[0023] [1] A method for preparing a calcium-based absorbent, characterized in that it comprises the following steps:

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

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

[0026] Step 3) subjecting the mixture to solvent thermal modification to obtain a slurry;

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

[0028] [2] The preparation method according to [1], wherein in step 1), the calcium-based raw material is one or more of limestone, snail shells or seashells.

[0029] [3] The preparation method according to [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 the step 1), the calcination temperature is 700°C to 1100°C.

[0031] [5] The preparation method according to any one of [1] to [4], wherein in the 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 the step 3), the temperature of the solvent thermal 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 the 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 comprising the following steps:

[0035] Step 5) Grinding and sieving the calcium-based absorbent to make the particle size of the calcium-based absorbent no more than 0.3 mm.

[0036] [9] A calcium-based absorbent obtained by the production method according to any one of [1] to [8].

[0037]

[10] Use of the calcium-based absorbent described in [9] for absorbing carbon dioxide or sulfur dioxide.

[0038] Effects of the Invention

[0039] The preparation method of the calcium-based absorbent of the present invention uses a large amount of industrial crude glycerol to modify the calcium-based absorbent, and a loosely organized calcium-based absorbent is prepared. The preparation process is simple, the raw materials are cheap, and the calcium-based absorbent can be applied to large-scale production. The calcium-based absorbent of the present invention has a high cycle conversion rate and a stable pore structure, is not easy to be sintered and deactivated, has the advantages of high efficiency, excellent performance, good pollutant treatment effect, etc., and can still maintain a good gas absorption capacity even if carbon dioxide and sulfur dioxide are absorbed in multiple cycles. BRIEF DESCRIPTION OF THE DRAWINGS

[0040] Figure 1 The CO2 capture capacity of the calcium-based absorbent prepared at different modification times in Example 1 of the present invention after 40 cycles of calcination.

[0041] Figure 2 The CO2 capture capacity of the calcium-based absorbent prepared at different modification temperatures in Example 2 of the present invention after 40 cycles of calcination.

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

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

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

[0045] Various exemplary embodiments, features and aspects of the present invention will be described in detail below. The word "exemplary" used here means "used as an example, embodiment or illustrative". Any embodiment described here as "exemplary" is not necessarily interpreted as being superior or better than other embodiments.

[0046] In addition, in order to better illustrate the present invention, numerous specific details are provided in the following specific embodiments. It should be understood by those skilled in the art that the present invention can be implemented without certain specific details. In other examples, methods, means, equipment and steps well known to those skilled in the art are not described in detail in order to highlight the subject matter of the present invention.

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

[0048] In this specification, the word "may" means both performing a certain process and not performing a certain process.

[0049] In this specification, the references to "some specific / preferred embodiments", "other specific / preferred embodiments", "embodiments", etc., mean that the specific elements (e.g., features, structures, properties and / or characteristics) described in connection with the embodiments are included in at least one embodiment described herein, and may or may not exist in other embodiments. In addition, it should be understood that the elements may be combined in various embodiments in any suitable manner.

[0050] In this specification, the numerical range expressed using "a numerical value A to a numerical value B" means a range including the endpoints numerical values ​​A and B.

[0051] The present invention provides a method for preparing a calcium-based absorbent, characterized in that it comprises the following steps:

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

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

[0054] Step 3) subjecting the mixture to solvent thermal modification to obtain a slurry;

[0055] Step 4) calcining 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 formula 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 the step 1), the calcium-based raw material is one or more of limestone, snail shells or shells.

[0058] According to the preparation method of the present invention, in the 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 the step 1), the calcination temperature is 700°C to 1100°C.

[0060] The glycerol comes from crude glycerol, a by-product of the biodiesel production process.

[0061] According to the preparation method of the present invention, in the 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 the content range of raw materials containing calcium oxide, the calcium-based absorbent material can be effectively modified, and the calcium-based absorbent obtained by the reaction can still maintain good absorption performance even after multiple recycling. If the content of raw materials containing calcium oxide is too high, it will lead to insufficient dissolution, affect the dynamic precipitation process, and the degree of change of the pore structure on the surface of the material is low; if the content of raw materials containing calcium oxide is too low, more glycerol is used. Although glycerol can be recycled, the energy consumption of the process will also increase.

[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 the step 3), the temperature of the solvent thermal modification is 120°C to 200°C and the time is 10 to 20 hours. At room temperature and pressure, the solubility of calcium oxide in glycerol is low, but in the process of solvent thermal modification in the present invention, calcium oxide can be dissolved in glycerol and fully modified (forming a complex), and a calcium-based absorbent with a large specific surface area and abundant pores is obtained in the subsequent calcination process.

[0065] The temperature of the solvent thermal modification is 120° C. to 200° C., preferably 160° C. to 200° C. If the temperature is too low, the calcium oxide will not be fully dissolved, resulting in insufficient modification and insignificant effect; if the temperature is too high, the energy consumption will be large and the cost will be higher.

[0066] The solvent thermal modification time is 10 to 20 hours, preferably 12 to 20 hours. If the solvent thermal modification time is too short, the modification will be insufficient and the pore structure will not be superior enough; if the solvent thermal modification time is too long, the physical properties of the absorbent will be poor, the energy consumption will be high, and the use effect of the calcium-based absorbent will be reduced.

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

[0068] This calcination temperature can completely burn and remove the glycerol remaining on the surface, and the pore structure can be retained.

[0069] According to the preparation method of the present invention, it also includes the following steps:

[0070] Step 5) Grinding and sieving the calcium-based absorbent to make the particle size of the calcium-based absorbent no more than 0.3 mm.

[0071] The present invention also provides a calcium-based absorbent, which is the calcium-based absorbent obtained according to the preparation method of the present invention.

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

[0073] Taking the absorption of carbon dioxide as an example, the calcium-based absorbent of the present invention has significantly improved carbon dioxide absorption capacity in multiple cycle reactions, which is particularly obvious in natural materials that are easy to obtain in practice. Taking the natural material of field snail shell calcium oxide as an example, the conversion rate is within 5% after 40 cycles, while glycerol-modified calcium oxide can still be maintained at around 20% under optimal conditions. The calcium-based absorbent prepared by the present invention has excellent anti-sintering performance and can maintain a macroporous stable pore structure in high-temperature cycles. The structure can effectively slow down high-temperature sintering, thereby maintaining its high adsorption activity, so that the calcium-based absorbent has excellent cyclic absorption characteristics.

[0074] Example

[0075] In order to make the purpose, technical scheme and advantages of the present invention more clearly understood, the present invention is further described in detail below in conjunction with the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are only used to explain the present invention and are not intended to limit the present invention. In addition, the technical features involved in the various embodiments of the present invention described below can be combined with each other as long as they do not conflict with each other.

[0076] Example 1-1

[0077] Field snail shells are used as calcium-based raw materials, and the calcium-based raw materials are calcined at 900° C. for 2 hours to obtain a raw material containing calcium oxide; 1 g of the raw material containing calcium oxide is fully mixed with 40 ml of glycerol under stirring conditions to obtain a mixture; the mixture is solvent-thermally modified to obtain a slurry; and the slurry is calcined to obtain a calcium-based absorbent 1-1.

[0078] The specific conditions of solvent thermal modification and calcination are shown in Table 1.

[0079] Example 1-2

[0080] The same method as Example 1-1 was adopted to change the specific conditions of solvent thermal modification and calcination to obtain calcium-based absorbent 1-2.

[0081] The specific conditions of solvent thermal modification and calcination are shown in Table 1.

[0082] Examples 1-3

[0083] The same method as Example 1-1 was used to change the specific conditions of solvent thermal modification and calcination to obtain calcium-based absorbent 1-3.

[0084] The specific conditions of solvent thermal modification and calcination are shown in Table 1.

[0085] Table 1

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

[0087] Performance Testing

[0088] The performance of calcium-based absorbents 1-1, 1-2, and 1-3 was tested, and a CO2 cyclic capture experiment was carried out in a thermogravimetric reactor: 1) The calcium-based absorbent was heated to 900°C at 40°C / min under N2 conditions and maintained for 5 minutes; 2) Then, the temperature was lowered to 650°C for carbon capture (CO2 concentration was 15 vol.%, reaction time was 15 minutes, CaO+CO2→CaCO3); 3) Then, the temperature was raised to 900°C and maintained for 5 minutes for adsorbent regeneration (reaction time was 2 minutes, CaCO3→CaO+CO2↑); 4) Processes 2)-3) were repeated for 40 reaction cycles. The results are shown in Figure 1 shown.

[0089] Example 2-1

[0090] Field snail shells are used as calcium-based raw materials, and the calcium-based raw materials are calcined at 900° C. for 2 hours to obtain a raw material containing calcium oxide; 1 g of the raw material containing calcium oxide is fully mixed with 40 ml of glycerol under stirring conditions to obtain a mixture; the mixture is solvent-thermally modified to obtain a slurry; and the slurry is calcined to obtain a calcium-based absorbent 2-1.

[0091] The specific conditions of solvent thermal modification and calcination are shown in Table 2.

[0092] Example 2-2

[0093] The same method as Example 2-1 was adopted to change the specific conditions of solvent thermal modification and calcination to obtain calcium-based absorbent 2-2.

[0094] The specific conditions of solvent thermal modification and calcination are shown in Table 2.

[0095] Example 2-3

[0096] The same method as Example 2-1 was used to change the specific conditions of solvent thermal modification and calcination to obtain calcium-based absorbent 2-3.

[0097] The specific conditions of solvent thermal modification and calcination are shown in Table 2.

[0098] Table 2

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

[0100] Performance Testing

[0101] The performance of calcium-based absorbents 2-1, 2-2, and 2-3 was tested, and a CO2 cyclic capture experiment was carried out in a thermogravimetric reactor: 1) The calcium-based absorbent was heated to 900°C at 40°C / min under N2 conditions and maintained for 5 minutes; 2) Then, the temperature was lowered to 650°C for carbon capture (CO2 concentration was 15 vol.%, reaction time was 15 minutes, CaO+CO2→CaCO3); 3) Then, the temperature was raised to 900°C and maintained for 5 minutes for adsorbent regeneration (reaction time was 2 minutes, CaCO3→CaO+CO2↑); 4) Processes 2)-3) were repeated for 40 reaction cycles. The results are shown in Figure 2 shown.

[0102] Example 3-1

[0103] Field snail shells are used as calcium-based raw materials, and the calcium-based raw materials are calcined at 900° C. for 2 hours to obtain a raw material containing calcium oxide; 1 g of the raw material containing calcium oxide is fully mixed with 40 ml of glycerol under stirring conditions to obtain a mixture; the mixture is solvent-thermally modified to obtain a slurry; and the slurry is calcined to obtain a calcium-based absorbent 3-1.

[0104] The specific conditions of solvent thermal modification and calcination are shown in Table 3.

[0105] Example 3-2

[0106] The same method as in Example 3-1 was adopted to add sodium hydroxide to the mixture, and the raw materials containing calcium oxide were added in a mass ratio of sodium hydroxide to calcium oxide = 1:9 to obtain a calcium-based absorbent 3-2.

[0107] The specific conditions of solvent thermal modification, doping and calcination are shown in Table 3.

[0108] Example 3-3

[0109] The same method as in Example 3-1 was adopted to add magnesium acetate to the mixture, and the raw materials containing calcium oxide were added in a mass ratio of magnesium acetate to 1:9 to obtain a calcium-based absorbent 3-3.

[0110] The specific conditions of solvent thermal modification, doping and calcination are shown in Table 3.

[0111] Table 3

[0112] Example Modification temperature / ℃ Modification time / h Adulterated substances Calcination temperature / ℃ 3-1 160 20 none 850 3-2 160 20 Sodium hydroxide 850 3-3 160 20 Magnesium acetate 850

[0113] Performance Testing

[0114] The performance of calcium-based absorbents 3-1, 3-2, and 3-3 was tested, and a CO2 cyclic capture experiment was carried out in a thermogravimetric reactor: 1) The calcium-based absorbent was heated to 900°C at 40°C / min under N2 conditions and maintained for 5 minutes; 2) Then, the temperature was lowered to 650°C for carbon capture (CO2 concentration was 15 vol.%, reaction time was 15 minutes, CaO+CO2→CaCO3); 3) Then, the temperature was raised to 900°C and maintained for 5 minutes for adsorbent regeneration (reaction time was 2 minutes, CaCO3→CaO+CO2↑); 4) Process 2)-3) was repeated for 40 reaction cycles. The results are shown in Figure 3 shown.

[0115] Example 4

[0116] The calcium-based absorbent 3-3 was subjected to a CO2 cycle capture experiment in a thermogravimetric reactor: 1) The calcium-based absorbent was heated to 900°C at 40°C / min under N2 conditions and maintained for 5 minutes; 2) Then, the temperature was lowered to 650°C for carbon capture (CO2 concentration was 15 vol.%, reaction time was 15 minutes, CaO+CO2→CaCO3); 3) Then, the temperature was raised to 900°C and maintained for 5 minutes for adsorbent regeneration (reaction time was 2 minutes, CaCO3→CaO+CO2↑); 4) Process 2)-3) was repeated for 40 reaction cycles. Then SEM test was performed, and the results are shown as follows: Figure 4 shown.

[0117] Comparative Example 1

[0118] The natural material field snail shell was calcined at 900°C for 2 hours to obtain a raw material containing calcium oxide, which was recorded as calcium-based absorbent-to-1.

[0119] A CO2 cyclic capture experiment was conducted in a thermogravimetric reactor: 1) The calcium-based absorbent was heated to 900°C at 40°C / min under N2 conditions and maintained for 5 minutes; 2) Then, the temperature was lowered to 650°C for carbon capture (CO2 concentration was 15 vol.%, reaction time was 15 minutes, CaO+CO2→CaCO3); 3) Then, the temperature was raised to 900°C and maintained for 5 minutes for adsorbent regeneration (reaction time was 2 minutes, CaCO3→CaO+CO2↑); 4) Process 2)-3) was repeated for 40 reaction cycles. Then SEM test was performed, and the results are shown in the figure. Figure 5 shown.

[0120] like Figure 4 As shown in , the calcium-based absorbent 3-3 has a rich pore structure and can maintain a macroporous and stable pore structure in a high-temperature cyclic reaction. This structure can effectively slow down high-temperature sintering, thereby maintaining a high adsorption activity, making the calcium-based absorbent have excellent cyclic absorption characteristics. Figure 5 Among them, the calcium-based absorbent-pair 1 has a smoother surface, less porosity, and weaker CO2 capture activity.

Claims

1. A method for preparing a calcium-based absorbent, characterized in that: The steps include: Step 1) calcining a calcium-based raw material to obtain a raw material containing calcium oxide; Step 2) mixing the raw material containing calcium oxide with glycerol to obtain a mixture; Step 3) subjecting the mixture to solvent thermal modification to obtain a slurry; Step 4) calcining the slurry to obtain a calcium-based absorbent.

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

3. The preparation method according to claim 1 or 2, wherein In the step 1), the particle size of the raw material containing calcium oxide is 20 μm to 2 mm.

4. The preparation method according to any one of claims 1 to 3, wherein In the step 1), the calcination temperature is 700°C to 1100°C.

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

6. The preparation method according to any one of claims 1 to 5, wherein In the step 3), the temperature of the solvent thermal modification is 120° C. to 200° C. and the time is 10 to 20 hours.

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

8. The preparation method according to any one of claims 1 to 7, further comprising the following steps: Step 5) Grinding and sieving the calcium-based absorbent to make the particle size of the calcium-based absorbent no more than 0.3 mm.

9. A calcium-based absorbent, which is a calcium-based absorbent obtained by the preparation method according to any one of claims 1 to 8.

10. Use of the calcium-based absorbent according to claim 9 for absorbing carbon dioxide or sulfur dioxide.

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