A solid amine adsorbent and its preparation method and application

Abstract

The present invention belongs to the field of carbon capture technology, specifically relating to a solid amine adsorbent, its preparation method, and application. The preparation method comprises: uniformly mixing a sulfoaluminum gelling material and a porous material, adding calcium stearate and hydroxypropyl methylcellulose, and then adding an aqueous solution of an organic amine to form a slurry. A foaming agent is added to the slurry, stirred and foamed, and then transferred to a mold for hydration and hardening. The adsorbent of the present invention is simple to prepare, the process is easily controllable, adsorbent molding and amine loading are completed in one step, and it has strong adsorption capacity and high mechanical strength.

Description

Technical Field

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

[0002] The information disclosed in this background technology section is only intended to enhance understanding of the overall background of the invention and should not necessarily be regarded as an admission or any form of suggestion that the information constitutes the prior art already known to those skilled in the art.

[0003] As global climate change intensifies, reducing carbon dioxide (CO2) emissions has become a pressing environmental issue. Industrial combustion flue gases (e.g., coal-fired power plants and steel mills) and direct air capture (DAC) are key approaches to CO2 reduction, and developing efficient, low-energy carbon capture technologies is a key challenge. While traditional liquid amine absorption methods (e.g., monoethanolamine, MEA) have been industrialized, they suffer from high energy consumption (solvent regeneration), equipment corrosion, and solvent loss due to volatilization. Consequently, solid amine adsorbents have become a research hotspot due to their advantages such as low energy regeneration, high selectivity, and non-corrosive properties.

[0004] Currently, many solid adsorbents, such as graphene and biochar, are in powder form. In industrial applications, the accumulation of fine powders in fixed beds can lead to a sharp increase in bed pressure drop and reduced heat and mass transfer efficiency. In fluidized bed systems, powders are easily entrained in the airflow, resulting in adsorbent loss, increased exhaust gas treatment load, and even secondary pollution. To address these issues, researchers are working on developing molding technologies that convert powdered adsorbents into structured particles. These molding technologies can be categorized as direct and indirect. Direct molding techniques (such as sol-gel, coprecipitation, hydrothermal synthesis, and microemulsion) integrate material synthesis and particle formation into a single step. However, these methods are often limited to specific material systems and require demanding reaction conditions (such as high temperature and pressure). These complex processes also result in low mechanical strength and uneven size of the resulting particles, making them difficult to meet industrial needs. In contrast, indirect molding techniques (such as extrusion and casting) process powders into macroscopic particles through mechanical compaction or the addition of binders, offering the advantages of ease of operation and scalability. However, this type of method also has significant defects: for example, the high pressure during the extrusion process may destroy the original pore structure of the adsorbent, causing the pores to collapse or densify, hindering the gas diffusion dynamics; and the binders used in the casting method are mostly non-porous materials, which may cover the active surface of the adsorbent or block the pores, resulting in a decrease in specific surface area and a significant decrease in adsorption capacity.

[0005] The main methods for preparing solid amine adsorbents include physical impregnation, chemical grafting, and in-situ polymerization. Physical impregnation utilizes the pores of a porous carrier to achieve amine loading. Chemical grafting forms a covalent bond between the amine and the porous carrier to achieve amine loading. In-situ polymerization directly polymerizes amine monomers (such as epichlorohydrin reacting with amine to form polyamine) in the carrier pores. Chemical grafting and in-situ polymerization are relatively complex processes and have high costs. Physical impregnation is currently the most widely used loading method, but studies have found that adsorbents prepared by physical impregnation have the following shortcomings: (1) long loading time, uneven loading (including inside and outside, top and bottom), and easy damage to the adsorbent during the loading process; (2) the use of methanol as a solvent and stirring and drying equipment during the loading process are required, which is costly and energy-consuming, and long-term high-temperature drying can easily cause the amine to volatilize and decompose due to heat; (3) the adsorbent molding and amine loading are carried out in steps, resulting in a complex process. Summary of the Invention

[0006] To address the shortcomings of existing technologies, the present invention provides a solid amine adsorbent, its preparation method, and its application. Based on the concept of "molding and loading simultaneously in time and space," the present invention utilizes a sulfoaluminum gelling material as a matrix composite porous material. Incorporating foaming technology, the solid amine adsorbent is synthesized in a single step, leveraging the water solubility of amines and the exothermic hydration properties of the gelling material. The adsorbent is suitable for carbon capture applications.

[0007] In order to achieve the above object, the technical solution of the present invention is:

[0008] In a first aspect, the present invention provides a method for preparing a solid amine adsorbent, which specifically comprises the following steps: uniformly mixing a binder and a porous material, adding calcium stearate and hydroxypropyl methylcellulose, and then adding an aqueous solution of an organic amine to form a slurry, adding a foaming agent to the slurry for stirring and foaming, and transferring the slurry to a mold for hydration and hardening reaction to obtain the slurry.

[0009] To prepare and shape the porous material, the present invention uses a binder, which can be either an organic or inorganic binder. The present invention uses an inorganic binder. To ensure high strength without destroying the pore structure of the porous material, the present invention uses a high-strength, fast-setting sulphoaluminum gelling material as a binder. Sulphoaluminum gelling materials are generally made from limestone, bauxite, and gypsum, and are relatively expensive. To reduce the cost of sulphoaluminum gelling materials, and thereby reduce the cost of the adsorbent, the present invention uses solid waste-based sulphoaluminum gelling materials.

[0010] However, since the sulfoaluminum gel is not a porous material and has an extremely low porosity, it increases the density of the adsorbent. Moreover, after being composited with the porous material, it will wrap the porous material to a certain extent, significantly reducing the adsorption performance of the adsorbent. To avoid the reduction in adsorption performance after the sulfoaluminum gel is composited with the porous material, the present invention uses foaming technology to increase the porosity of the sulfoaluminum gel, fully exposing the porous material, thereby forming a three-dimensional interconnected hierarchical pore structure encompassing "micropores, mesopores, and macropores." This reduces the overall density of the adsorbent, provides more attachment sites for the amine active component, and improves the diffusion path for carbon dioxide, thereby improving the adsorption performance of the adsorbent.

[0011] In order to avoid the adverse effects of existing loading methods on shaped adsorbents, the present invention adopts a "molding-loading time and space co-construction" mechanism, utilizing the water solubility of amines to dissolve amines in water for hydration of the gelling material, and then utilizing the exothermic hydration of the gelling material to drive the in-situ anchoring of the amine molecules. This can not only eliminate the "immersion-drying" steps of the traditional loading method, greatly reducing the production cycle and cost, but also enable the amine to be completely and evenly loaded in the adsorbent, avoiding problems such as amine loss and pore blockage in the loading process, amine volatilization and decomposition in the drying process, and low amine loading capacity and adsorption performance of the prepared adsorbent and large variability.

[0012] In a second aspect, a solid amine adsorbent is obtained by the above preparation method.

[0013] In a third aspect, an application of the above-mentioned solid amine adsorbent in carbon capture, especially the adsorption and capture of carbon dioxide.

[0014] The beneficial effects of the present invention are:

[0015] (1) The present invention uses sulfur-aluminum gelling material to cast and shape the porous material, which increases the mechanical strength of the adsorbent, can be well adapted to complex on-site application environments, and has the feasibility of being applied to industrial devices such as fixed beds and fluidized beds; the gelling material has good fluidity during the hydration process, can be compounded with most porous materials, and can also retain the inherent porosity of the material. The preparation process is simple and does not require harsh reaction conditions.

[0016] (2) The present invention couples "material composite, sulfur-aluminum hydration, and foaming technology" to spontaneously form a three-dimensional interconnected hierarchical pore structure covering "micropores-mesopores-macroporos" inside the adsorbent, avoiding the problem of porous materials being structurally destroyed and encapsulated, and improving the mass transfer efficiency and adsorption performance of the formed adsorbent.

[0017] (3) The "molding-loading time and space co-construction" mechanism adopted by the present invention avoids the use of hazardous chemicals, the investment of high-energy-consuming equipment, and the problems of long amine loading cycle and poor uniformity, greatly reducing the production cycle and cost.

[0018] (4) The solid waste-based sulfoaluminum gelling material used in the present invention is produced by sintering a solid waste mixture, turning waste into treasure and realizing waste resource utilization. In addition, the adsorbent of the present invention, prepared using the solid waste-based sulfoaluminum gelling material as raw material, is used for carbon capture, achieving the effect of treating waste with waste. BRIEF DESCRIPTION OF THE DRAWINGS

[0019] The accompanying drawings, which constitute a part of the present invention, are used to provide a further understanding of the present invention. The exemplary embodiments of the present invention and their descriptions are used to explain the present invention and do not constitute improper limitations on the present invention.

[0020] Figure 1 These are the conceptual structural diagram, optical microscope diagram and electron microscope diagram of the composite structured solid amine adsorbent in Example 1 without amine loading; among them, (a) is the conceptual structural diagram of the composite structured solid amine adsorbent without amine loading; (b) optical microscope diagram; (c) electron microscope diagram.

[0021] Figure 2 The mercury intrusion pattern, X-CT pattern, XRD pattern and compressive strength pattern of the composite structured solid amine adsorbent in Example 1 without amine loading; wherein, (a) mercury intrusion pattern of the composite structured solid amine adsorbent without amine loading; (b) X-CT pattern; (c) XRD pattern; (d) compressive strength pattern.

[0022] Figure 3 This is a comparison chart of the adsorption performance of the one-step synthesized composite structured solid amine adsorbent in Example 1, the traditional physical impregnation powdered solid amine adsorbent in Comparative Examples 1 to 5, and different composite structured solid amine adsorbents. DETAILED DESCRIPTION

[0023] It should be noted that the following detailed descriptions are exemplary and intended to provide further explanation of the present invention. 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 invention belongs.

[0024] 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 invention. As used herein, unless the context clearly indicates otherwise, the singular form is intended to include the plural form. 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.

[0025] In view of the defects of the prior art in preparing solid amine adsorbents, such as long amine loading time, uneven loading, low mechanical strength, and complicated preparation process, the present invention proposes a solid amine adsorbent, a preparation method, and an application thereof.

[0026] In a first aspect, the present invention provides a method for preparing a solid amine adsorbent, which specifically comprises the following steps: uniformly mixing a sulfoaluminum gelling material and a porous material, adding calcium stearate and hydroxypropyl methylcellulose, and then adding an aqueous solution of an organic amine to form a slurry, adding a foaming agent to the slurry for stirring and foaming, and transferring the slurry to a mold for hydration and hardening reaction to obtain the amine adsorbent.

[0027] In one or more embodiments, the amount of porous material added is 10-60% of the mass of the sulfoaluminum gelling material added, preferably 25-35%.

[0028] In one or more embodiments, calcium stearate can effectively reduce the amount of water added, which is beneficial to improving the strength of the adsorbent. The amount of calcium stearate added is 0.5-2% of the mass of the sulfoaluminum gelling material added.

[0029] In one or more embodiments, hydroxypropyl methylcellulose improves the consistency of the mud and enables bubbles to be uniformly and stably present in the gel during the foaming process. The amount of hydroxypropyl methylcellulose added is 1-2% of the mass of the sulfoaluminum gelling material added.

[0030] In one or more embodiments, the foaming agent is selected from a chemical foaming agent or a physical foaming agent. The chemical foaming agent is H2O2 or NaHCO3, and the physical foaming agent is a prefabricated foam. A preferred mass fraction of H2O2 is 30%, and more preferably, the 30% H2O2 is added in an amount of 1-6% of the mass of the sulfoaluminum gelling material. If the addition amount is less than 1%, insufficient gas is generated by decomposition of H2O2, resulting in low porosity, high density, and difficulty in forming a uniform porous structure. If the addition amount is too high, the excess gas is rapidly released, potentially forming overly large or uneven pores, which significantly reduces the mechanical strength of the adsorbent.

[0031] In one or more embodiments, the stirring and foaming time is 1.5 to 2.5 minutes. If the stirring and foaming time is too short, H2O2 is not fully decomposed and oxygen is not fully released, resulting in low porosity and uneven bubble distribution. Insufficient stirring time may cause bubbles to aggregate locally, forming large pores. If the stirring time is too long, continued stirring may destroy existing bubbles, resulting in increased pore size and even causing bubbles to leave the cementitious material and be released into the environment.

[0032] In one or more embodiments, the mold is a particle mold. The particle mold has a diameter of 3 to 10 mm, preferably 5 mm.

[0033] In one or more embodiments, the hydration and hardening reaction time is 2 to 7 days.

[0034] In one or more embodiments, the sulfoaluminum gelling material is a solid waste-based sulfoaluminum gelling material obtained by mixing and calcining desulfurized gypsum, aluminum ash, red mud, and carbide slag in a mass ratio of 20-25:15-19:22-30:30-35; the calcination temperature is 1200-1300°C, and the calcination time is 25-35 minutes.

[0035] In one or more embodiments, the porous material is selected from one or more of a carbon-based material, a silicon-based material, an aluminum-based material, a resin-based material, or a metal-organic framework. The carbon-based material is selected from biochar, activated carbon, carbon nanotubes, graphene, and the like; the silicon-based material is selected from ordered mesoporous silicon materials (such as MCM-41, SBA-15), molecular sieves (such as 13X, ZSM-5), silica gel, and the like; the aluminum-based material is selected from γ-Al2O3, mesoporous alumina, aluminum-based composite oxides, metal-loaded alumina, and the like; the resin-based material is selected from macroporous adsorption resins (such as X-5, HP-20), ion exchange resins (such as strong acid 001×7, weak base D301), Amberlite IRA series (such as IRA-900), and the like; and the metal-organic framework is selected from ZIF-8, UiO-66, MIL-101, MOF-74, HKUST-1, and the like.

[0036] Preferably, the porous material is biochar. Considering the source and cost of the porous material, the biochar is obtained by pyrolyzing corn stalks. The biochar has a pyrolysis temperature of 600-800°C, a pyrolysis temperature rise rate of 15-25°C / min, and a pyrolysis time of 3-5 hours. These temperature and time conditions ensure that the corn stalks are fully pyrolyzed to form biochar.

[0037] In one or more embodiments, the organic amine is selected from one or more of polyethyleneimine (PEI), tetraethylenepentamine, polyphthalamide, polyimide, polyacrylic acid, polypropylene glycol, polyglycolide, pentaethylenehexamine, etc. Preferably, the organic amine is selected from branched PEI (MW600), and the amount of PEI added is 50~250% of the added mass of the porous material, preferably 100~150%.

[0038] In a second aspect, the present invention provides a solid amine adsorbent prepared by the preparation method described in the first aspect.

[0039] In a third aspect, the present invention provides a use of the solid amine adsorbent prepared by the preparation method described in the first aspect or the solid amine adsorbent described in the second aspect in carbon capture.

[0040] The present invention is further described in detail below with reference to specific embodiments and accompanying drawings.

[0041] Example 1:

[0042] 1. Adsorbent preparation:

[0043] (1) Preparation of biochar: 30 g of corn stalks were crushed to pass through a 100-mesh sieve and pyrolyzed at high temperature to obtain biochar. The pyrolysis temperature was set at 600 °C, the temperature rise rate was 20 °C / min, and the time was 4 h.

[0044] (2) Preparation of solid waste-based sulfoaluminum cementitious material: 111.9 g of flue gas desulfurization gypsum, 84.1 g of aluminum ash, 139.2 g of red mud and 164.9 g of carbide slag were dried at 105 °C to constant weight, crushed to pass through a 200-mesh sieve and evenly mixed, water was added until it could be lumped into shape, and then dried at 110 °C for 2 h, and finally calcined at 1250 °C for 0.5 h to obtain solid waste-based sulfoaluminum cementitious material.

[0045] (3) Preparation of adsorbent: First, 6 g of solid waste-based sulfur-aluminum gelling material and 1.8 g of biochar were evenly mixed, 0.03 g of calcium stearate and 0.06 g of hydroxypropyl methylcellulose were added to the mixture and evenly mixed, then 2.7 g of PEI was dissolved in deionized water and added to the mixture and stirred evenly to form a slurry, then 0.162 mL of 30% H2O2 was added to the slurry and rapidly stirred for 2 min to foam, and finally the foamed slurry was moved to a particle mold with a diameter of 5 mm for hydration and hardening reaction. After standing and curing for 2 days, the mold was removed to obtain a one-step synthesized composite structured solid amine adsorbent.

[0046] 2. Performance Testing

[0047] (1) Characterization: In order to better observe the morphology of the one-step synthesized composite structured solid amine adsorbent and characterize the adsorbent structure, the unloaded amine adsorbent was tested using optical microscopy, SEM, mercury porosimeter, X-CT, XRD and single particle compressive strength tester.

[0048] Depend on Figure 1 It can be seen that when there is no amine loading, there is a composite mode of gelling material and porous material in the adsorbent, and there is a pore morphology and interconnection mode formed by the porous material and hydration and foaming.

[0049] Depend on Figure 2 It can be seen that the porosity of the adsorbent can reach 50% when there is no amine loading, which ensures that the adsorbent has a higher amine loading upper limit and a higher carbon dioxide diffusion rate; the single particle compressive strength is 77N, which ensures its anti-interference ability to the outside world and can adapt well to complex on-site application environments.

[0050] The elemental analysis of the solid adsorbent prepared in Example 1, the composite structured solid amine adsorbent without amine loading, and pure PEI is shown in Table 1.

[0051] Table 1

[0052]

[0053] According to calculation, the amine loading in the solid adsorbent prepared in Example 1 is about 20%.

[0054] (2) Adsorption performance: The adsorbent was placed in a synchronous thermal analyzer for adsorption experiments, where the adsorption atmosphere was 100% CO2 and the adsorption temperature was 90°C. The CO2 adsorption capacity per unit mass of the adsorbent can be calculated using the mass change before and after adsorption. The adsorption curve is shown in Figure 3 .

[0055] Comparative Example 1

[0056] 1. Adsorbent preparation

[0057] (1) Preparation of biochar: same as in Example 1.

[0058] (2) Preparation of adsorbent: First, 2 g of PEI was dissolved in 5 mL of methanol and ultrasonically shaken for 10 minutes to ensure uniform mixing. At the same time, 8 g of biochar was added to 10 mL of methanol and magnetically stirred to ensure that the biochar pores were fully opened. The pretreated biochar was then added to the PEI solution and magnetically stirred for 3-4 hours to ensure complete and uniform amine loading. Finally, it was placed in a vacuum drying oven and heated at 80°C for 8 hours to completely evaporate the methanol, thereby obtaining a solid amine adsorbent.

[0059] 2. Performance Testing

[0060] Adsorption performance: The operation steps are the same as in Example 1. The results are shown in Figure 3 .

[0061] Comparative Example 2

[0062] 1. Adsorbent preparation:

[0063] (1) Preparation of solid waste-based sulfoaluminum gelling material: same as Example 1.

[0064] (2) Preparation of adsorbent: First, 6 g of solid waste-based sulfoaluminum gelling material, 0.03 g of calcium stearate and 0.06 g of hydroxypropyl methylcellulose were uniformly mixed. Deionized water was added to the mixture until it could be stirred evenly to form a slurry. The foamed slurry was then transferred to a particle mold with a diameter of 5 mm for hydration and hardening reaction, and then allowed to stand for 2 days. The adsorbent was then demolded and added to methanol, and magnetically stirred to ensure that the adsorbent pores were fully opened. At the same time, 20% of the adsorbent mass of PEI was dissolved in 5 mL of methanol and ultrasonically vibrated for 10 minutes to ensure uniform mixing. The pretreated adsorbent was then added to the PEI solution and magnetically stirred for 12 hours to ensure complete and uniform amine loading. Finally, it was placed in a vacuum drying oven and heated at 80 ° C for 8 hours to completely evaporate the methanol to obtain a solid amine adsorbent.

[0065] 2. Performance Testing

[0066] Adsorption performance: The operation steps are the same as in Example 1. The results are shown in Figure 3 .

[0067] Comparative Example 3

[0068] 1. Adsorbent preparation:

[0069] (1) Preparation of solid waste-based sulfoaluminum gelling material: same as Example 1.

[0070] (2) Preparation of adsorbent: First, 6 g of solid waste-based sulfoaluminum gelling material, 0.03 g of calcium stearate and 0.06 g of hydroxypropyl methylcellulose were uniformly mixed. Deionized water was added to the mixture until it could be stirred evenly to form a slurry. Then, 0.162 mL of 30% H2O2 was added to the slurry and stirred rapidly for 2 minutes to foam. The foamed slurry was then transferred to a particle mold with a diameter of 5 mm for hydration and hardening reaction and allowed to stand for 2 days. The adsorbent was then demolded and added to methanol and magnetically stirred to ensure that the adsorbent pores were fully opened. At the same time, 20% of the adsorbent mass of PEI was dissolved in 5 mL of methanol and ultrasonically vibrated for 10 minutes to ensure uniform mixing. The pretreated adsorbent was then added to the PEI solution and magnetically stirred for 12 hours to ensure complete and uniform amine loading. Finally, it was placed in a vacuum drying oven and heated at 80 °C for 8 hours to completely evaporate the methanol to obtain a solid amine adsorbent.

[0071] 2. Performance Testing

[0072] Adsorption performance: The operation steps are the same as in Example 1. The results are shown in Figure 3 .

[0073] Comparative Example 4

[0074] 1. Adsorbent preparation:

[0075] (1) Preparation of biochar: same as in Example 1.

[0076] (2) Preparation of solid waste-based sulfaluminum cementitious material: same as Example 1.

[0077] (3) Preparation of adsorbent: First, 6 g of solid waste-based sulfur-aluminum gelling material and 1.8 g of biochar were uniformly mixed. 0.03 g of calcium stearate and 0.06 g of hydroxypropyl methylcellulose were added to the mixture and mixed uniformly. Deionized water was added to the mixture until it could be stirred evenly to form a slurry. The foamed slurry was then transferred to a particle mold with a diameter of 5 mm for hydration and hardening reaction, and then allowed to stand for 2 days. The adsorbent was then demolded and added to methanol, and magnetically stirred to ensure that the adsorbent pores were fully opened. At the same time, 20% of the adsorbent mass of PEI was dissolved in 5 mL of methanol and ultrasonically vibrated for 10 minutes to ensure uniform mixing. The pretreated adsorbent was then added to the PEI solution and magnetically stirred for 12 hours to ensure complete and uniform amine loading. Finally, it was placed in a vacuum drying oven and heated at 80 ° C for 8 hours to completely evaporate the methanol to obtain a solid amine adsorbent.

[0078] 2. Performance Testing

[0079] Adsorption performance: The operation steps are the same as in Example 1. The results are shown in Figure 3 .

[0080] Comparative Example 5

[0081] 1. Adsorbent preparation:

[0082] (1) Preparation of biochar: same as in Example 1.

[0083] (2) Preparation of solid waste-based sulfaluminum cementitious material: same as Example 1.

[0084] (3) Preparation of adsorbent: First, 6 g of solid waste-based sulfur-aluminum gelling material and 1.8 g of biochar were uniformly mixed. 0.03 g of calcium stearate and 0.06 g of hydroxypropyl methylcellulose were added to the mixture and mixed uniformly. Deionized water was added to the mixture until it could be stirred uniformly to form a slurry. Then, 0.162 mL of 30% H2O2 was added to the slurry and stirred rapidly for 2 minutes to foam. The foamed slurry was then transferred to a particle mold with a diameter of 5 mm for hydration and hardening reaction. The slurry was then left to stand for 2 days. The adsorbent was then demolded and added to methanol and magnetically stirred to ensure that the adsorbent pores were fully opened. At the same time, 20% of the adsorbent mass of PEI was dissolved in 5 mL of methanol and ultrasonically vibrated for 10 minutes to ensure uniform mixing. The pretreated adsorbent was then added to the PEI solution and magnetically stirred for 12 hours to ensure complete and uniform amine loading. Finally, it was placed in a vacuum drying oven and heated at 80 °C for 8 hours to completely evaporate the methanol to obtain a solid amine adsorbent.

[0085] 2. Performance Testing

[0086] Adsorption performance: The operation steps are the same as in Example 1. The results are shown in Figure 3 .

[0087] Depend on Figure 3As shown, the carbon dioxide adsorption capacity of each adsorbent is in the order of Comparative Example 1 > Example 1 > Comparative Example 5 > Comparative Example 4 > Comparative Example 3 > Comparative Example 2. Due to the improved adsorption performance of the adsorbents using composite biochar and the combined foaming technology, the adsorbents prepared in Example 1 and Comparative Example 5 have superior carbon dioxide adsorption capacities to those prepared in Comparative Examples 2, 3, and 4. Furthermore, due to the "molding-loading spatiotemporal co-construction" mechanism, amine loading is complete and uniform, making the adsorbent prepared in Example 1 superior to the adsorbent prepared in Comparative Example 5.

[0088] Comparative Example 1 is a powder adsorbent. When the bulk is small (only 10 mg of sample is required in the simultaneous thermal analysis experiment), due to its low density and light weight, the loose powders and large pores, the mass transfer is better and the amine is more easily exposed. Therefore, Comparative Example 1 exhibits superior adsorption. The adsorbent in Example 1 simultaneously constructs a three-dimensional interconnected hierarchical pore structure during molding, alleviating the poor accessibility of carbon dioxide and amines caused by molding. This makes the structured adsorbent prepared in Example 1 essentially equivalent to the powder adsorbent prepared in Comparative Example 1.

[0089] The foregoing description is merely a preferred embodiment of the present invention and is not intended to limit the present invention. Those skilled in the art will readily appreciate that various modifications and variations of the present invention are possible. Any modifications, equivalent substitutions, or improvements made within the spirit and principles of the present invention are intended to be within the scope of protection of the present invention.

Claims

1. A method for preparing a solid amine adsorbent for carbon capture, characterized in that: The following steps are involved: The aluminum sulfate gel material and the porous material are mixed evenly, and then calcium stearate and hydroxypropyl methylcellulose are added, and then an aqueous solution of an organic amine is added to make a slurry, a foaming agent is added to the slurry to stir and foam, and the slurry is transferred to a mold for hydration and hardening reaction to obtain the product; The stirring and foaming time is 1.5 to 2.5 minutes, and the hydration and hardening reaction time is 2 to 7 days; The sulphoaluminium gelling material is a solid waste-based sulphoaluminium gelling material; the solid waste-based sulphoaluminium gelling material is obtained by mixing and calcining desulphurized gypsum, aluminium ash, red mud and carbide slag in a mass ratio of 20-25:15-19:22-30:30-35; the calcination temperature is 1200-1300°C, and the calcination time is 25-35 minutes; The foaming agent is H2O2 with a mass fraction of 30%, and the added amount is 1-6% of the mass of the sulfur-aluminum gelling material; The porous material is selected from one or more of carbon-based materials, silicon-based materials, aluminum-based materials, resin-based materials, and metal-organic frameworks.

2. The preparation method according to claim 1, characterized in that The amount of porous material added is 10~60% of the mass of the sulfur-aluminum gelling material added.

3. The preparation method according to claim 1, characterized in that The added amount of calcium stearate is 0.5~2% of the added mass of the sulphoaluminum gelling material, and the added amount of hydroxypropyl methylcellulose is 1~2% of the added mass of the sulphoaluminum gelling material.

4. The preparation method according to claim 1, characterized in that The organic amine is selected from one or more of polyethyleneimine, tetraethylenepentamine and pentaethylenehexamine.

5. A solid amine adsorbent prepared by the method according to any one of claims 1 to 4.

6. Use of the solid amine adsorbent prepared by the method according to any one of claims 1 to 4 or the solid amine adsorbent according to claim 5 in carbon capture.

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