Carbon dioxide solid adsorbent and preparation method therefor

Abstract

The present invention relates to the technical field of carbon dioxide capture, and in particular to a carbon dioxide solid adsorbent and a preparation method therefor. The carbon dioxide solid adsorbent comprises the following raw materials in parts by weight: 2-10 parts of a functional buffer agent, 5-15 parts of chitosan, 3-12 parts of streptomycin, 120-180 parts of desulfurized gypsum, and 90-100 parts of water. The carbon dioxide solid adsorbent is applied to capture of carbon dioxide in desulfurized flue gas, and the content of ammonia in the desulfurized flue gas is 0.5-2.5 mg / m3; and the adsorption temperature of the carbon dioxide solid adsorbent is 35-45°C, and the desorption temperature is 70-90°C. The carbon dioxide solid adsorbent in the present invention significantly increases the adsorption rate and the adsorption capacity thereof to carbon dioxide, has along cycle service life, and can stably maintain a high carbon dioxide adsorption rate and adsorption capacity for a long time. In addition, the adsorbent has low desorption temperature, stable performance, non-corrosiveness, and no need for an additional antioxidant, is environmentally friendly and easily degradable, and has no additional pollution.

Description

A carbon dioxide solid adsorbent and preparation method thereof Technical Field

[0001] The present invention relates to the technical field of carbon dioxide capture, and in particular to a carbon dioxide solid adsorbent and a preparation method thereof. Background Art

[0002] Over the past century, human society has experienced rapid industrialization, and the use of large amounts of fossil fuels has emitted large amounts of greenhouse gases such as carbon dioxide. Excessive greenhouse gases intercept the long-wave radiation energy emitted from the earth's surface, forming a greenhouse effect that causes global warming, thereby changing the ecological balance and threatening human survival.

[0003] Carbon dioxide capture and storage technology is one of the effective ways to solve the continued increase in atmospheric carbon dioxide concentration. The development of new high-efficiency and low-energy adsorbents will help promote the large-scale application of this technology.

[0004] Currently, carbon dioxide capture technologies can be divided into chemical absorption separation, membrane separation, physical adsorption, etc. Among them, chemical absorption separation is the most widely used and mature method, with advantages such as low energy consumption, no corrosion, simple operation, and easy automation control. For example, the most commonly used organic amine absorption method. However, organic amine compounds are second only to organic sulfides in odorous pollutants and can cause environmental pollution.

[0005] Chitosan is a macromolecular structure derived from the deacetylation of chitin, extracted from the shells of shrimp, crab, and other animals. It is not only widely available in nature but also contains abundant amino and hydroxyl groups. It is non-toxic, odorless, biodegradable, and has excellent biocompatibility. Compared to organic amines, chitosan contains a higher abundance of amino groups and is biocompatible, effectively reducing wastewater treatment process steps and economic costs, and has the potential for large-scale industrial application.

[0006] However, chitosan has a low specific surface area and poor adsorption performance. At the same time, the amino group has a strong binding force with carbon dioxide, so desorption must be achieved at a higher temperature, and the energy consumption of adsorbent regeneration is high.

[0007] In view of this, the present invention is proposed.

[0008] Summary of the Invention

[0009] The object of the present invention is to provide a solid carbon dioxide adsorbent and a preparation method thereof. The solid carbon dioxide adsorbent of the present invention has a long cycle life and can stably maintain a high carbon dioxide adsorption rate and adsorption capacity for a long time.

[0010] In a first aspect, the present invention provides a solid adsorbent for carbon dioxide, comprising the following raw materials in parts by weight:

[0011] 2-10 parts of functional buffer, 5-15 parts of chitosan, 3-12 parts of streptomycin, 120-180 parts of desulfurized gypsum and 90-100 parts of water;

[0012] The carbon dioxide solid adsorbent is used to capture carbon dioxide in desulfurized flue gas, and the ammonia content in the desulfurized flue gas is 0.5-2.5 mg / m 3 ;

[0013] The adsorption temperature of the carbon dioxide solid adsorbent is 35-45°C, and the desorption temperature is 70-90°C.

[0014] The carbon dioxide solid adsorbent of the invention is prepared from a mixture of a functional buffer, chitosan, streptomycin, desulfurized gypsum and water under the conditions of thermal expansion, natural cooling, refrigeration and freeze drying in sequence.

[0015] During the thermal expansion process, desulfurization gypsum mainly serves as the adsorbent carrier skeleton. Under the condition of heating in a sealed reactor, acid-soluble chitosan with thermal expansion and contraction characteristics can fully expand inside the skeleton of the desulfurization gypsum and form multiple fluffy pores on its surface, thereby increasing the specific surface area of ​​the adsorbent and improving the carbon dioxide adsorption rate and adsorption capacity.

[0016] During the natural cooling process, the chloride salts contained in the desulfurization gypsum itself can absorb moisture from the air. Part of the adsorbed moisture condenses when rapidly refrigerated. After further vacuum freeze-drying, the moisture is directly converted from the solid phase to the gas phase, which not only enriches the pore structure of the adsorbent but also avoids the problem of internal pore closure. The other part of the adsorbed moisture can be captured by the Tris functional buffer as ionized water, thereby enabling the solid Tris particles to be integrated into the entire adsorbent skeleton in the form of a solution, thereby making the desulfurization gypsum skeleton weakly alkaline, giving the adsorbent skeleton structure the ability to quickly adsorb carbon dioxide, thereby solving the problem of the limited carbon dioxide adsorption capacity of the desulfurization gypsum itself. At the same time, because the desulfurization gypsum is rich in relatively abundant magnesium chloride and calcium chloride, the moisture it absorbs is sufficient to keep the Tris particles in liquid form for a long time and not flow. Therefore, the adsorbent of the present invention has a long cycle life and can stably maintain a high carbon dioxide adsorption efficiency for a long time.

[0017] In addition, streptomycin has the characteristic of still producing alkaline products after hydrolysis with carbon dioxide acidic gas, which not only extends the service life of the adsorbent, but also avoids the problem of low adsorbent capacity and adsorption efficiency caused by adsorbent acidification.

[0018] The carbon dioxide solid adsorbent prepared by the present invention is mainly used for the adsorption of carbon dioxide in power plant flue gas. This is because power plant flue gas contains a small amount of ammonia. The main component of desulfurization gypsum is calcium sulfate. When calcium sulfate coexists with ammonia and carbon dioxide, it can not only capture carbon dioxide, but also convert calcium sulfate into calcium carbonate and ammonium sulfate, effectively preventing the escape of carbon dioxide gas. The generated calcium carbonate and ammonium sulfate can be used as chemical raw materials.

[0019] Furthermore, the carbon dioxide solid adsorbent of the present invention has an adsorption temperature of 35-45° C. and can be directly applied to the rear end of the desulfurization flue gas emission pipeline of a power plant. It has a low desorption temperature, low energy consumption, and is easy to use on a large scale.

[0020] The functional buffer used in the present invention is preferably solid Tris particles. The Tris functional buffer can maintain the overall adsorbent in a weakly alkaline environment. It has a high carbon dioxide adsorption rate and efficiency, and its properties are stable and it does not react with calcium, magnesium and heavy metal ions.

[0021] The chitosan used in the present invention is preferably acid-soluble chitosan, which is weakly alkaline and has a higher purity than water-soluble chitosan.

[0022] The Tris-functional buffer in this invention relies on trace amounts of water in the adsorbent to function properly. Therefore, to ensure the Tris-functional buffer remains liquid and immobile for extended periods, the desulfurized gypsum used must contain a certain amount of chloride salts. This chloride salts maintain the desulfurized gypsum's ability to absorb moisture from the air. Research has shown that a chloride salt content of 2-5% by weight in the desulfurized gypsum maintains its ability to absorb moisture over a long period of time.

[0023] In addition, before the desulfurization gypsum of the present invention is used, it needs to be crushed and sieved in sequence, and the mesh size of the sieve used during sieving is 60-100 meshes.

[0024] In a second aspect, the present invention further provides a method for preparing the above-mentioned solid carbon dioxide adsorbent, comprising the following steps:

[0025] S1. Add solid Tris particles to water to prepare a weakly alkaline functional buffer;

[0026] S2. Add chitosan, streptomycin and desulfurized gypsum to the functional buffer in sequence, stir evenly, and obtain a mixed viscous substance;

[0027] S3, filling the mixed viscous material into a mold;

[0028] S4. Place the mold in a sealed reactor and heat it at 130-180° C. for 4-6 hours, followed by natural cooling, refrigeration and vacuum freeze drying to obtain a solid carbon dioxide adsorbent.

[0029] It can be seen that the preparation method of the present invention is simple, does not require the addition of additional antioxidants, surfactants and other reagents, is environmentally friendly, easily degradable, and does not cause additional pollution.

[0030] As a preferred embodiment of the present technical solution, in step S2, chitosan is added to the functional buffer solution, and magnetic stirring is performed for 0.5-1 h at a stirrer speed of 60-200 rpm.

[0031] As a preferred embodiment of the present technical solution, in step S2, streptomycin is added to the functional buffer solution, and the mixture is rapidly stirred at a stirrer speed of 60-80 rpm, and the stirring time is controlled to be 2-5 min.

[0032] As a preferred embodiment of the present technical solution, in step S3, the mold includes any one or more of a honeycomb mold, a sheet mold, a tubular mold and an annular mold.

[0033] As a preferred embodiment of the present technical solution, in step S4, after the mold is naturally cooled to room temperature, it is demoulded and the resulting product is refrigerated at -15 to -5°C for 1 to 3 hours.

[0034] As a preferred embodiment of the present technical solution, in step S4, the refrigerated product is placed in a freeze dryer at -65°C and freeze-dried for 24-48 hours to obtain a solid carbon dioxide adsorbent.

[0035] The carbon dioxide solid adsorbent and preparation method thereof of the present invention have at least the following technical effects:

[0036] 1. The carbon dioxide solid adsorbent of the present invention is mainly composed of a mixture of a functional buffer, chitosan, streptomycin, desulfurized gypsum and water, which is prepared in sequence under the conditions of thermal expansion, natural cooling, refrigeration and freeze drying. During the preparation process, desulfurized gypsum is mainly used as the adsorbent carrier skeleton. Utilizing the thermal expansion and contraction characteristics of solid acid-soluble chitosan, under the condition of heating in a sealed reactor, chitosan can fully expand inside the skeleton of the desulfurized gypsum and form a plurality of fluffy pores on its surface, thereby increasing the specific surface area of ​​the adsorbent and improving the carbon dioxide adsorption rate and adsorption capacity. During the natural cooling process, the chloride salts contained in the desulfurized gypsum itself can absorb moisture from the air. A portion of the adsorbed moisture condenses when rapidly refrigerated. After further vacuum freeze drying, the moisture is directly converted from the solid phase to the gas phase, which not only enriches the pore structure of the adsorbent, but also avoids the problem of internal pore closure. The remaining adsorbed water can be captured as ionized water by the Tris functional buffer, allowing the solid Tris particles to be incorporated into the entire adsorbent framework in a solution state. This renders the desulfurized gypsum framework weakly alkaline, endowing the adsorbent framework structure with the ability to rapidly adsorb carbon dioxide, thereby resolving the problem of the desulfurized gypsum's inherently limited carbon dioxide adsorption capacity. Furthermore, because desulfurized gypsum is rich in magnesium chloride and calcium chloride, the water it absorbs is sufficient to keep the Tris particles in a liquid form for extended periods without flowing. Therefore, the adsorbent of the present invention has a long cycle life and can stably maintain a high carbon dioxide adsorption efficiency over an extended period.

[0037] 2. Although the adsorbent prepared by the present invention using Tris functional buffer, chitosan and desulfurized gypsum has the ability to rapidly adsorb carbon dioxide, its adsorption capacity still needs to be further improved. Therefore, the present invention further introduces streptomycin to increase the adsorption capacity and rate of the adsorbent. Streptomycin has the characteristic of still producing alkaline products after hydrolysis with carbon dioxide acid gas, which not only extends the service life of the adsorbent, but also avoids the problem of low adsorbent capacity and adsorption efficiency caused by adsorbent acidification.

[0038] 3. The main adsorption material of the present invention is chitosan, a natural polymer material rich in amino groups. It is rich in a large number of amino groups, has a fast adsorption rate and a low desorption temperature. At the same time, it has stable performance, is non-corrosive and does not require the addition of additional antioxidants. It is environmentally friendly and easy to degrade, and there is no additional pollution.

[0039] 4. The present invention uses desulfurization gypsum as the adsorbent skeleton material, whose main component is calcium sulfate. When calcium sulfate coexists with ammonia and carbon dioxide, it can not only capture carbon dioxide, but also convert calcium sulfate into calcium carbonate and ammonium sulfate, effectively preventing the escape of carbon dioxide gas. The generated calcium carbonate and ammonium sulfate can be used as chemical raw materials. At the same time, after the entire reaction system is placed in a mold, chitosan fully expands under heating conditions, and a dense porous structure can be constructed inside the desulfurization gypsum skeleton, further increasing the specific surface area and improving the reaction rate.

[0040] 5. The Tris functional buffer used in the present invention not only ensures that the adsorbent is weakly alkaline as a whole, maintaining a high carbon dioxide adsorption rate and efficiency, but also has stable properties and does not react with calcium, magnesium and heavy metal ions. BRIEF DESCRIPTION OF THE DRAWINGS

[0041] In order to more clearly illustrate the specific embodiments of the present invention or the technical solutions in the prior art, the following briefly introduces the drawings required for use in the specific embodiments or the description of the prior art. Obviously, the drawings described below are some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying any creative work.

[0042] FIG1 is a graph showing the change in cyclic adsorption efficiency of the solid adsorbent for carbon dioxide obtained in Example 1 of the present invention. DETAILED DESCRIPTION

[0043] It should be noted that the following detailed descriptions are illustrative and intended to provide further explanation of the present application. Unless otherwise specified, all technical and scientific terms used herein have the same meaning as commonly understood by those skilled in the art to which the present application belongs.

[0044] It should be noted that the terms used herein are only for describing specific embodiments and are not intended to limit the exemplary embodiments according to the present application. As used herein, unless the context clearly indicates otherwise, the singular also includes the plural. In addition, it should be understood that when the terms "comprise" and / or "include" are used in this specification, they indicate the presence of features, steps, operations, devices, components and / or combinations thereof.

[0045] The following will clearly and completely describe the technical solutions of the present invention in conjunction with the embodiments. Obviously, the embodiments described are only some embodiments of the present invention, not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making creative efforts are within the scope of protection of the present invention.

[0046] Example 1

[0047] S11, adding 10 g of solid Tris particles to 90 g of water to prepare a weakly alkaline functional buffer;

[0048] S12, add 12g acid-soluble chitosan to the functional buffer, and stir with magnetic stirring at a stirrer speed of 100rpm for 1h; then add 8g streptomycin, and stir mechanically at a stirrer speed of 80rpm for 3min, and finally add 150g desulfurized gypsum, stir thoroughly to obtain a mixed viscous material;

[0049] S13, pouring the mixed viscous material into a honeycomb mold;

[0050] S14. Place the honeycomb mold in a sealed reactor and heat it at 150°C for 5 hours. After natural cooling, refrigerate it at -10°C for 2 hours. Finally, place it in a freeze dryer at -65°C for freeze drying for 24-48 hours to obtain a solid carbon dioxide adsorbent.

[0051] Example 2

[0052] S21. Add 8 g of solid Tris particles to 92 g of water to prepare a weakly alkaline functional buffer;

[0053] S22, 15g of acid-soluble chitosan was added to the functional buffer, and the mixture was stirred magnetically for 1h at a stirrer speed of 200rpm; then 8g of streptomycin was added, and the mixture was stirred mechanically for 5min at a stirrer speed of 60rpm, and finally 150g of desulfurized gypsum was added and stirred thoroughly to obtain a mixed viscous material;

[0054] S23, pouring the mixed viscous material into a honeycomb mold;

[0055] S24. Place the honeycomb mold in a sealed reactor and heat it at 150°C for 5 hours. After natural cooling, refrigerate it at -10°C for 2 hours. Finally, place it in a freeze dryer at -65°C for freeze drying for 24-48 hours to obtain a solid carbon dioxide adsorbent.

[0056] Example 3

[0057] S31, adding 2 g of solid Tris particles to 98 g of water to prepare a weakly alkaline functional buffer;

[0058] S32, 12g of acid-soluble chitosan was added to the functional buffer, and the stirrer was magnetically stirred at a speed of 200rpm for 1h; then 8g of streptomycin was added, and the stirrer was mechanically stirred at a speed of 80rpm for 5min, and finally 150g of desulfurized gypsum was added and stirred thoroughly to obtain a mixed viscous material;

[0059] S33, pouring the mixed viscous material into a honeycomb mold;

[0060] S34. Place the honeycomb mold in a sealed reactor and heat it at 150°C for 5 hours. After natural cooling, refrigerate it at -10°C for 2 hours. Finally, place it in a freeze dryer at -65°C for freeze drying for 24-48 hours to obtain a solid carbon dioxide adsorbent.

[0061] Example 4

[0062] S41, adding 10 g of solid Tris particles to 90 g of water to prepare a weakly alkaline functional buffer;

[0063] S42, 15g of acid-soluble chitosan was added to the functional buffer, and the mixture was stirred magnetically for 1h at a stirrer speed of 200rpm; then 8g of streptomycin was added, and the mixture was stirred mechanically for 5min at a stirrer speed of 80rpm, and finally 180g of desulfurized gypsum was added and stirred thoroughly to obtain a mixed viscous material;

[0064] S43, pouring the mixed viscous material into a honeycomb mold;

[0065] S44. Place the honeycomb mold in a sealed reactor and heat it at 180°C for 4 hours. After natural cooling, refrigerate it at -10°C for 2 hours. Finally, place it in a freeze dryer at -65°C for freeze drying for 24-48 hours to obtain a solid carbon dioxide adsorbent.

[0066] Example 5

[0067] S51, adding 10 g of solid Tris particles to 90 g of water to prepare a weakly alkaline functional buffer;

[0068] S52, 5g of acid-soluble chitosan was added to the functional buffer, and the mixture was magnetically stirred at a stirrer speed of 100 rpm for 0.5h; then 8g of streptomycin was added, and the mixture was mechanically stirred at a stirrer speed of 60 rpm for 5min, and finally 120g of desulfurized gypsum was added and stirred thoroughly to obtain a mixed viscous material;

[0069] S53, pouring the mixed viscous material into a honeycomb mold;

[0070] S54. Place the honeycomb mold in a sealed reactor and heat it at 150°C for 5 hours. After natural cooling, refrigerate it at -10°C for 2 hours. Finally, place it in a freeze dryer at -65°C for freeze drying for 24-48 hours to obtain a solid carbon dioxide adsorbent.

[0071] Example 6

[0072] S61. Add 10 g of solid Tris particles to 90 g of water to prepare a weakly alkaline functional buffer;

[0073] S62, add 12g of acid-soluble chitosan to the functional buffer, and stir with magnetic stirring at a stirrer speed of 200rpm for 1h; then add 12g of streptomycin, and stir mechanically at a stirrer speed of 80rpm for 5min, and finally add 150g of desulfurized gypsum, stir thoroughly to obtain a mixed viscous material;

[0074] S63, pouring the mixed viscous material into a honeycomb mold;

[0075] S64. Place the honeycomb mold in a sealed reactor and heat it at 150°C for 5 hours. After natural cooling, refrigerate it at -10°C for 2 hours. Finally, place it in a freeze dryer at -65°C for freeze drying for 24-48 hours to obtain a solid carbon dioxide adsorbent.

[0076] Comparative Example 1

[0077] Using silica alumina carrier instead of desulfurization gypsum in Example 1;

[0078] The other steps and parameters are basically the same as those in Example 1.

[0079] Comparative Example 2

[0080] Lysine was used to replace the Tris functional buffer in Example 1;

[0081] The other steps and parameters are basically the same as those in Example 1.

[0082] Comparative Example 3

[0083] Polyethyleneimine was used instead of streptomycin in Example 1;

[0084] The other steps and parameters are basically the same as those in Example 1.

[0085] The adsorption performance of the adsorbent was tested using the pipeline ventilation method. The entire test process was carried out in a glove box. The simulated power plant flue gas contained 0.5-2.5mg / m 3 Ammonia and carbon dioxide gas (35-45°C) was fed into a pipeline containing the solid carbon dioxide adsorbent of the present invention. Carbon dioxide concentration meters were installed at both the inlet and outlet of the pipeline to monitor adsorption performance. The gas flow rate throughout the test setup was controlled by a flow meter at 2 L / min. The adsorption process was instantaneous, with concentrations measured at both the inlet and outlet, achieving a one-time adsorption efficiency. Table 1 shows the adsorption performance test results.

[0086] Table 1 Adsorption performance test results

[0087] As shown in Table 1, the carbon dioxide solid adsorbent prepared by the present invention has better adsorption capacity than that of control examples 1-3. Its instantaneous adsorption rate for carbon dioxide at a concentration of 500 ppm reaches more than 99.1%, and the single saturated adsorption capacity can reach 1452 mg / g.

[0088] Comparative Example 1 uses silica alumina as a carrier. Although it increases the specific surface area of ​​chitosan and streptomycin to a certain extent, due to its poor water absorption, after heat treatment, the Tris functional buffer will be released in the form of particles due to water loss, which seriously limits the effect of the Tris functional buffer, not only reducing the adsorption capacity of the adsorbent, but also reducing its cycle life.

[0089] In Control Example 2, lysine was used to replace the Tris functional buffer of the present invention, and the adsorption efficiency was relatively low. The reason may be that some lysine was lost, decomposed or denatured during the sealed high-pressure heating preparation process.

[0090] Comparative Example 3 uses polyethyleneimine instead of the streptomycin of the present invention. Although polyethyleneimine also contains abundant amino groups, it has a high viscosity, overlaps with the action of TRIS, and does not have the ability to protect the adsorbent from acidification.

[0091] In order to further study the stability of the carbon dioxide solid adsorbent prepared by the present invention, the present invention conducted an adsorption-desorption cycle test on the carbon dioxide solid adsorbent prepared in Example 1, wherein the desorption conditions of the adsorbent are: placing the adsorbent under 80°C blast heating conditions for 3 hours.

[0092] FIG1 is a graph showing the change in cyclic adsorption efficiency of the solid adsorbent for carbon dioxide obtained in Example 1 of the present invention.

[0093] As shown in FIG1 , the carbon dioxide adsorbent prepared by the present invention can still maintain a relatively high carbon dioxide adsorption capacity after undergoing 50 adsorption-desorption cycles, and its saturated adsorption capacity can still reach 1385 mg / g.

[0094] In summary, the carbon dioxide adsorbent of the present invention has good carbon dioxide adsorption capacity and cyclic regeneration stability. In particular, the carbon dioxide adsorbent prepared under the conditions of Example 4 has a saturated carbon dioxide adsorption capacity of up to 1476 mg / g and excellent cyclic regeneration performance, with the adsorption capacity decreasing by less than 8% after 50 cycles.

[0095] It can be seen that the preparation method of the present invention is simple, does not require the addition of additional antioxidants, surfactants and other reagents, has a low desorption temperature, stable performance, is environmentally friendly and easy to degrade, and does not cause additional pollution; moreover, the carbon dioxide adsorbent can significantly improve the stability of the adsorbent regeneration while maintaining a high carbon dioxide adsorption capacity, greatly improving the life and long-term cycle service life of the carbon dioxide solid adsorbent, and can be widely used in the capture process of carbon dioxide gas in power plant flue gas.

[0096] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, rather than to limit it. Although the present invention has been described in detail with reference to the above embodiments, those skilled in the art should understand that they can still modify the technical solutions described in the above embodiments, or replace some or all of the technical features therein with equivalents. However, these modifications or replacements do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of the present invention.

Claims

1. A solid adsorbent for carbon dioxide, characterized in that: The invention comprises the following raw materials in parts by weight: 2-10 parts of functional buffer, 5-15 parts of chitosan, 3-12 parts of streptomycin, 120-180 parts of desulfurized gypsum and 90-100 parts of water; The carbon dioxide solid adsorbent is used to capture carbon dioxide in desulfurized flue gas, and the ammonia content in the desulfurized flue gas is 0.5-2.5 mg / m 3 ; The adsorption temperature of the carbon dioxide solid adsorbent is 35-45°C, and the desorption temperature is 70-90°C.

2. The solid adsorbent for carbon dioxide according to claim 1, characterized in that: The functional buffer is solid Tris particles.

3. The solid adsorbent for carbon dioxide according to claim 1, characterized in that: The chitosan is acid-soluble chitosan.

4. The solid adsorbent for carbon dioxide according to claim 1, characterized in that: The mass content of chloride salt in the desulfurized gypsum is 2-5%; Before the desulfurized gypsum is used, it is crushed and sieved in sequence, and the mesh number of the sieve used during sieving is 60-100 meshes.

5. The method for preparing the solid adsorbent for carbon dioxide according to any one of claims 1 to 4, characterized in that: The following steps are involved: S1. Add solid Tris particles into water to prepare a weakly alkaline functional buffer; S2, adding chitosan, streptomycin and desulfurized gypsum to the functional buffer in sequence, stirring evenly to obtain a mixed viscous substance; S3, filling the mixed viscous material into a mold; S4. Place the mold in a sealed reactor and heat it at 130-180° C. for 4-6 hours, followed by natural cooling, refrigeration and vacuum freeze drying to obtain a solid carbon dioxide adsorbent.

6. The preparation method according to claim 5, characterized in that: In step S2, chitosan is added to the functional buffer, and magnetic stirring is performed for 0.5-1 h at a stirrer speed of 60-200 rpm.

7. The preparation method according to claim 5, characterized in that: In step S2, streptomycin is added to the functional buffer, and mechanical stirring is performed for 2-5 minutes at a stirring speed of 60-80 rpm.

8. The preparation method according to claim 5, characterized in that: In step S3, the mold includes any one or more of a honeycomb mold, a sheet mold, a tubular mold and a ring mold.

9. The preparation method according to claim 5, characterized in that: In step S4, after the mold is naturally cooled to room temperature, the mold is removed and the resulting product is refrigerated at -15 to -5°C for 1 to 3 hours.

10. The preparation method according to claim 5, characterized in that: In step S4, the refrigerated product is placed in a freeze dryer at -65°C for freeze drying for 24-48 hours to obtain a solid carbon dioxide adsorbent.

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