Solid amine adsorbent, preparation method thereof and CO2 trapping process

Abstract

The invention discloses a solid amine adsorbent, a preparation method thereof and a CO2 trapping process, the solid amine adsorbent comprises a hydroxyl-containing oxide carrier, the surface of the oxide carrier is loaded with fluoroalkylsilane and aminophilic alkylsilane, the number of carbon atoms in the fluoroalkylsilane is at least four more than the number of carbon atoms in the aminophilic alkylsilane, and the number of carbon atoms in the aminophilic alkylsilane is at least four more than the number of carbon atoms in the aminophilic alkylsilane. The aminophilic alkyl silane is distributed between the adjacent fluoroalkyl silane; the surface of the oxide carrier is also loaded with organic amine, and the organic amine and the aminophilic alkyl silane form adsorption combination. According to the invention, the adsorption capacity and the cycle stability of the solid amine adsorbent can be better improved.

Description

Technical Field

[0001] This application relates to the technical field of CO2 capture, and in particular to a solid amine adsorbent and its preparation method, as well as a CO2 capture process. Background Technology

[0002] Solid amine adsorbents have attracted much attention in carbon dioxide capture due to their advantages such as low regeneration energy consumption and mild operating conditions. However, solid amine adsorbents suffer from low adsorption capacity and poor cycle stability, which seriously affect their carbon dioxide capture efficiency. Summary of the Invention

[0003] To improve the adsorption capacity and cycle stability of solid amine adsorbents, this application discloses a solid amine adsorbent, its preparation method, and a CO2 capture process.

[0004] In one aspect, embodiments of this application provide a solid amine adsorbent.

[0005] A solid amine adsorbent includes a hydroxyl-containing oxide support, wherein a fluoroalkylsilane and an amine-loving alkylsilane are loaded on the surface of the oxide support, wherein the fluoroalkylsilane has at least 4 more carbon atoms than the amine-loving alkylsilane, and the amine-loving alkylsilane is distributed between adjacent fluoroalkylsilanes. The oxide support surface is also loaded with an organic amine, and the organic amine forms an adsorption bond with the amine-loving alkylsilane.

[0006] As an optional implementation, in the embodiments of this application, the fluoroalkylsilane has 8 to 22 carbon atoms, and the amine-loving alkylsilane has 1 to 6 carbon atoms.

[0007] As an optional implementation, in the embodiments of this application, the fluoroalkylsilane includes one or a combination of two of 1H,1H,2H,2H-perfluorooctyltriethoxysilane and 1H,1H,2H,2H-perfluorodecyltrichlorosilane. The amine-affinity alkylsilane includes amine-affinity alkylsilanes and / or amine-reactive alkylsilanes, wherein the amine-affinity alkylsilane includes one or a combination of two of 3-aminopropyltriethoxysilane and N-2-aminoethyl-3-aminopropyltrimethoxysilane. The amine-reactive alkylsilane includes one or a combination of two of 3-glycidyl etheroxypropyltriethoxysilane and 3-mercaptopropyltrimethoxysilane; The oxide support includes one or more of the following: silicon oxide support, aluminum oxide support, and titanium oxide support.

[0008] As an optional implementation, in the embodiments of this application, the loading of the fluoroalkylsilane is 2 wt.% to 8 wt.%, and the loading of the amine-loving alkylsilane is 1 wt.% to 6 wt.%.

[0009] As an optional implementation, in the embodiments of this application, the oxide carrier surface has micron-level grooves, cones, microneedles or dendritic structures, and the roughness factor of the oxide carrier surface is 10~500.

[0010] As an optional implementation, in the embodiments of this application, the loading of the organic amine is 20 wt.%~65 wt.%; and / or; The organic amine includes one or more combinations of polyethyleneimine, pentaethylenehexamine, and tetraethylenepentamine.

[0011] Secondly, embodiments of this application provide a method for preparing a solid amine adsorbent.

[0012] A method for preparing a solid amine adsorbent, comprising the following steps as described in any of the first aspects: The fluoroalkylsilane is loaded onto the surface of the oxide support, followed by the loading of the amine-loving alkylsilane; The organic amine is then loaded and adsorbed between the organic amine and the amine-loving alkylsilane to obtain the solid amine adsorbent.

[0013] As an optional implementation, in the embodiments of this application, the reaction of loading the fluoroalkylsilane includes: reacting the fluoroalkylsilane with the oxide support at 60°C to 80°C for 3 to 4 hours; The reaction of loading the amine-loving alkylsilane includes: reacting the oxide support loaded with the fluoroalkylsilane with the amine-loving alkylsilane at 60°C to 100°C for 2 h to 4 h; The organic amine is loaded by impregnation or grafting.

[0014] As an optional implementation, in the embodiments of this application, the preparation method of the solid amine adsorbent further includes: before loading the fluoroalkylsilane, the oxide support is subjected to surface roughening treatment, the surface roughening treatment including secondary particle stacking, plasma etching or template-assisted etching.

[0015] Thirdly, embodiments of this application provide a CO2 capture process.

[0016] In an air or flue gas environment, CO2 is captured using a solid amine adsorbent as described in the first aspect or a solid amine adsorbent prepared by the preparation method described in the second aspect. In the flue gas environment, NO ≤ 50 ppm, NO2 ≤ 50 ppm, SO2 ≤ 30 ppm, and H2O ≤ 15 vol%.

[0017] Compared with the prior art, the beneficial effects of this application are as follows: This application modulates the spatial distribution of amine-loving alkylsilanes and fluoroalkylsilanes on the oxide support surface, resulting in a more ordered and uniform composite arrangement of these two compounds. Fluoroalkylsilanes, with their longer fluoroalkyl structures, effectively enhance the surface hydrophobicity of the solid amine adsorbent and form hydrophobic patches through interactions with adjacent fluoroalkylsilanes, significantly improving the overall hydrophobic effect. Meanwhile, amine-loving alkylsilanes, with their amine-loving properties, provide adsorption sites and form stable adsorption bonds with organic amines, promoting uniform dispersion of organic amines on the oxide support surface. This allows for better expansion rather than aggregation of organic amines, effectively improving their utilization rate and increasing the adsorption capacity of the solid amine adsorbent. Furthermore, because the alkyl chains of amine-loving alkylsilanes are shorter and located below the hydrophobic patches, they fully utilize the advantages of these patches, reducing the adverse effects of external moisture on the organic amines adsorbed on the amine-loving alkylsilanes. This also reduces the possibility of excessive proximity or intertwining with fluoroalkylsilanes, facilitating better expansion of the organic amines bound to the amine-loving alkylsilanes. In summary, the synergistic combination of fluoroalkylsilanes of specific lengths and amine-loving alkylsilanes can significantly improve the moisture resistance and dispersibility of solid amine adsorbents, enabling them to maintain good carbon dioxide adsorption capacity and cycle stability even in high humidity environments. Attached Figure Description

[0018] To more clearly illustrate the technical solutions in the embodiments of this application, the accompanying drawings used in the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of this application. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0019] Figure 1 This is a schematic diagram disclosed in the embodiments of this application, illustrating the orderly distribution of fluoroalkylsilanes (PFOTES) and amine-loving alkylsilanes (MPTMS, AEAPTMS) on the surface of an oxide support; Figure 2 This is a schematic diagram of the surface structure of an oxide carrier that has undergone roughening treatment, as disclosed in the embodiments of this application. Detailed Implementation

[0020] The technical solutions of the embodiments of this application will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of this application, and not all embodiments. Based on the embodiments of this application, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of this application.

[0021] In this application, the terms "upper," "lower," "left," "right," "front," "rear," "top," "bottom," "inner," "outer," "middle," "vertical," "horizontal," "lateral," and "longitudinal" indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. These terms are primarily for the purpose of better describing this application and its embodiments, and are not intended to limit the indicated device, element, or component to having a specific orientation, or to be constructed and operated in a specific orientation.

[0022] Furthermore, in addition to indicating location or positional relationship, some of the aforementioned terms may also have other meanings. For example, the term "above" may also be used in some cases to indicate a certain dependency or connection relationship. Those skilled in the art can understand the specific meaning of these terms in this application based on the specific circumstances.

[0023] Furthermore, the terms "installation," "setup," "equipped with," "connection," and "linked" should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral structure; they can refer to a mechanical connection or an electrical connection; they can refer to a direct connection or an indirect connection through an intermediate medium, or an internal connection between two devices, components, or parts. Those skilled in the art can understand the specific meaning of these terms in this application based on the specific circumstances.

[0024] Furthermore, the terms "first," "second," etc., are primarily used to distinguish different devices, components, or parts (which may be the same or different in specific type and construction), and are not intended to indicate or imply the relative importance or quantity of the indicated devices, components, or parts. Unless otherwise stated, "a plurality of" means two or more.

[0025] Organic amines such as polyethyleneimine, pentaethylenehexamine, and tetraethylenepentamine are supported on oxide supports (such as mesoporous silica supports) to form solid amine adsorbents. However, the organic amine chains in these solid amine adsorbents exhibit aggregation, which reduces the number of accessible amine sites and results in low utilization. Furthermore, under high humidity or direct air capture (DAC) conditions, solid amine adsorbents are prone to competitive adsorption of water vapor, leading to significant performance degradation.

[0026] The technical solution of this application will be further described below with reference to the embodiments and accompanying drawings.

[0027] In one aspect, embodiments of this application provide a solid amine adsorbent.

[0028] A solid amine adsorbent includes a hydroxyl-containing oxide support, on the surface of which a fluoroalkylsilane and an amine-loving alkylsilane are loaded, wherein the fluoroalkylsilane has at least 4 more carbon atoms than the amine-loving alkylsilane, and the amine-loving alkylsilane is dispersed between adjacent fluoroalkylsilanes. The oxide support surface is also loaded with organic amines, and the organic amines form adsorption bonds with amine-loving alkylsilanes.

[0029] This application achieves a more ordered and uniform composite arrangement of amine-loving alkylsilanes and fluoroalkylsilanes on the oxide support surface by controlling the spatial distribution of these two compounds; wherein, for example... Figure 1 As shown, fluoroalkylsilanes such as 1H,1H,2H,2H-perfluorooctyltriethoxysilane (PFOTES) can effectively enhance the surface hydrophobicity of solid amine adsorbents due to their longer fluoroalkyl structures. They can also form hydrophobic patches by interacting with adjacent fluoroalkylsilanes, significantly improving the overall hydrophobic effect. Meanwhile, amine-loving alkylsilanes, with their amine-loving advantage, can provide adsorption sites and form stable adsorption bonds with organic amines, promoting the uniform dispersion of organic amines on the oxide support surface. This allows organic amines to spread better on the oxide support surface rather than agglomerate, effectively improving the utilization rate of organic amines and increasing the adsorption capacity of solid amine adsorbents. Furthermore, due to the shorter alkyl chain of the amine-loving alkylsilane, located below the hydrophobic plaque, it can fully utilize the advantages of the hydrophobic plaque, reducing the adverse effects of external moisture on the organic amines adsorbed on the amine-loving alkylsilane. It also reduces the possibility of excessive proximity or intertwining with fluoroalkylsilanes, facilitating better extension of the organic amine bound to the amine-loving alkylsilane. In summary, the synergistic combination of fluoroalkylsilanes and amine-loving alkylsilanes of specific lengths can significantly improve the moisture resistance and dispersibility of solid amine adsorbents, enabling them to maintain good carbon dioxide adsorption capacity and cycle stability even in high humidity environments (e.g., relative humidity greater than 40%).

[0030] For example, the number of carbon atoms in a fluoroalkylsilane can be 4, 6, 8, 10, 13, or 16 more than that in an amine-loving alkylsilane. Preferably, the number of carbon atoms in a fluoroalkylsilane is 7 more than that in an amine-loving alkylsilane. In this case, the fluoroalkylsilane has a longer alkyl chain length than the amine-loving alkylsilane, its surface energy is lower, and it can form better hydrophobic patches. The amine-loving alkylsilane has a shorter alkyl chain length than the fluoroalkylsilane, its extension is less, and it maintains a certain proximity to the organic amine. Therefore, the amine-loving alkylsilane can form a better bond with the organic amine, thus better improving the dispersibility of the organic amine.

[0031] In some embodiments, the number of carbon atoms in fluoroalkylsilanes is 8 to 22, and the number of carbon atoms in amine-loving alkylsilanes is 1 to 6.

[0032] Fluoroalkylsilanes and amine-loving alkylsilanes with specific carbon numbers can work synergistically to improve the moisture resistance of solid amine adsorbents and the dispersibility of organic amines. For example, the number of carbon atoms in fluoroalkylsilanes can be 8, 12, 16, and 22, while the number of carbon atoms in amine-loving alkylsilanes can be 1, 3, and 6.

[0033] In some embodiments, the fluoroalkylsilane includes one or a combination of two of 1H,1H,2H,2H-perfluorooctyltriethoxysilane and 1H,1H,2H,2H-perfluorodecyltrichlorosilane (FDTS). Amine-affinity alkylsilanes include amine-affinity alkylsilanes and / or amine-reactive alkylsilanes. Amine-affinity alkylsilanes include one or a combination of two of 3-aminopropyltriethoxysilane (APTES) and N-(2-aminoethyl)-3-aminopropyltrimethoxysilane (AEAPTMS). Amine-reactive alkylsilanes include one or a combination of two of 3-glycidyloxypropyltriethoxysilane (GPTES) and 3-mercaptopropyltrimethoxysilane (MPTMS). The aforementioned fluoroalkylsilanes meet the requirements of this application in terms of stericity and hydrophobicity, thereby providing the solid amine adsorbent of this application with superior cycle stability.

[0034] In this application, amine-affinitive alkylsilanes refer to those that enhance the dispersion of amines through hydrogen bonding, electrostatics, or van der Waals forces (e.g., containing groups that can form hydrogen bonds, such as hydroxyl, ether, or amino groups). Amine-reactive alkylsilanes refer to those containing reactive groups that can form covalent bonds with amines, enabling the covalent fixation or grafting of organic amines through chemical reactions. Both amine-affinitive and amine-reactive alkylsilanes can improve the dispersibility of organic amines, reduce the possibility of organic amine aggregation, and increase the utilization rate of organic amines.

[0035] Among them, amine-reactive alkylsilanes form bonds with organic amines through chemical reactions, which can more firmly immobilize organic amines, thereby effectively inhibiting amine aggregation or loss and improving the dispersibility and cycling stability of organic amines. Furthermore, 3-glycidyl etheroxypropyltriethoxysilane has an epoxy group, which can open the ring and undergo a covalent reaction with organic amines, thereby achieving the immobilization of organic amines. The thiol group in 3-mercaptopropyltrimethoxysilane can also react with organic amines under specific conditions (such as using a catalyst) to achieve the immobilization of organic amines.

[0036] In some embodiments, the oxide support includes one or more combinations of silica support, alumina support, and titanium oxide support. Further, the silica support can be dendritic mesoporous silica nanoparticles (DMSN), mesostructured cellular foams (MCF), or Santa Barbara amorphous-15 (SBA-15), etc., offering broad applicability.

[0037] In some embodiments, the loading of fluoroalkylsilane is 2 wt.% to 8 wt.%, and the loading of amine-loving alkylsilane is 1 wt.% to 6 wt.%.

[0038] By controlling the loading of fluoroalkylsilanes and amine-loving alkylsilanes within a specific range, the overall hydrophobicity and amine dispersibility of the solid amine adsorbent can be improved. At the same time, it can also provide direct or indirect adsorption binding sites for organic amine molecules, which is conducive to the adsorption of organic amines onto the surface of the oxide support through electrostatic interactions or van der Waals forces, and ensures that the pores are not completely blocked and the channels are maintained, which facilitates gas diffusion in the subsequent carbon dioxide adsorption process.

[0039] It should be noted that the loading amount is the mass ratio of the active component (e.g., fluoroalkylsilanes, amine-loving alkylsilanes, organic amines) to the support (e.g., oxide support). The loading amounts of fluoroalkylsilanes and amine-loving alkylsilanes can be determined using stepwise TGA (thermogravimetric analysis) or combined with elemental analysis (e.g., F or S elements).

[0040] In some embodiments, reference is made to Figure 2 The oxide carrier surface has micron-sized grooves, cones, microneedles or dendritic structures, and the roughness factor of the oxide carrier surface is 10~500.

[0041] The solid amine adsorbent of this application is in powder form, and the roughness factor can be approximated as:

[0042] Among them, S geo It is the "smooth" specific surface area (m²) calculated based on particle geometry. 2 / g), and the solid amine adsorbent powder of this application can be regarded as spherical particles, S geo The calculation formula is: (ρ is density, d is equivalent diameter); S BET (m) 2 The total specific surface area of ​​the powder is (g), which can be obtained by testing according to GB / T 20321-2006 "Measurement and Evaluation of Surface Morphology Parameters".

[0043] By constructing a macroscopically rough structure on an oxide support and then grafting it with fluoroalkylsilanes, a water contact angle of over 150° can be achieved, thereby significantly suppressing capillary condensation in a wet state and improving the moisture resistance of the solid amine adsorbent. For example, the roughness factor of the oxide support surface can be 10, 50, 100, 200, or 500. Further, the depth of the grooves, cones, microneedles, or dendritic structures on the oxide support surface is 0.2 μm-5 μm, preferably 0.5 μm-3 μm, and the spacing or period between adjacent structures is 0.2 μm-10 μm, preferably 0.5 μm-3 μm.

[0044] In some embodiments, the loading of organic amines in the solid amine adsorbent is 20 wt.% to 65 wt.%.

[0045] The organic amine loading in this application, within the aforementioned range, achieves superior dispersion on the oxide support surface. For example, the organic amine loading in the solid amine adsorbent can be 20 wt.%, 30 wt.%, 40 wt.%, 50 wt.%, or 65 wt.%, etc.

[0046] In some embodiments, the organic amine includes one or more combinations of polyethyleneimine, pentaethylenehexamine, and tetraethylenepentamine.

[0047] The aforementioned organic amines can be physically adsorbed onto the oxide support surface via electrostatic interactions and van der Waals forces. Simultaneously, the amine groups of the organic amines can form hydrogen bonds or undergo chemical reactions with the functional groups of amine-loving alkylsilanes, thereby being adsorbed onto the amine-loving alkylsilanes. Under the synergistic effect of these forces, the organic amines achieve stable and uniform dispersion on the oxide support surface, effectively inhibiting the aggregation of organic amine molecules and thus improving amine utilization.

[0048] Secondly, embodiments of this application provide a method for preparing a solid amine adsorbent.

[0049] A method for preparing a solid amine adsorbent, as described in any of the first aspects, includes the following steps: First, fluoroalkylsilanes are loaded onto the surface of an oxide support, followed by the loading of amine-loving alkylsilanes, and then the loading of organic amines, allowing adsorption to occur between the organic amines and the amine-loving alkylsilanes, thus obtaining a solid amine adsorbent.

[0050] The specific loading sequence described above is crucial for constructing ordered surface structures. Oxide support surfaces contain silanol sites with varying reactivity. Taking silica support as an example, isolated silanol sites exist independently, exhibiting strong acidity and high reactivity. Associated silanol sites are hydrogen-bonded together, exhibiting slightly weaker acidity and a slower reaction rate than isolated silanol sites. Bridged silanol sites, where both hydroxyl groups are located on the same silicon atom, exhibit the lowest acidity and the slowest reaction rate.

[0051] This application allows fluoroalkylsilanes with longer alkyl chains to preferentially react with oxide supports, selectively occupying highly active silanol sites (such as isolated silanols) on the surface of the silica support, thereby forming hydrophobic patches with certain gaps on the surface of the oxide support. The secondary active silanols retained in these gap regions provide sites for subsequent grafting of amine-loving alkylsilanes.

[0052] In contrast, when fluoroalkylsilanes and amine-loving alkylsilanes are mixed and reacted together with an oxide support, their random reaction on the oxide support surface easily leads to uneven distribution of the fluoroalkylsilanes and amine-loving alkylsilanes. This reduces the dispersion uniformity of the organic amines, causing them to aggregate, reducing amine utilization, and decreasing the moisture resistance of the solid amine adsorbent. If the reaction order is changed (amine-loving alkylsilanes are loaded first), the highly active sites on the oxide support surface will be occupied by amine-loving alkylsilanes first, making it difficult for subsequent grafting of long-chain fluoroalkylsilanes with greater steric hindrance, thus failing to form a complete hydrophobic protective layer. As a result, a large amount of organic amines are directly exposed to a humid environment, where water molecules easily interact with the organic amines, leading to a significant decrease in the moisture resistance of the solid amine adsorbent. Under humid conditions, both the CO2 adsorption capacity and cycling stability will decrease significantly.

[0053] Therefore, by regulating the reaction sequence of fluoroalkylsilanes and amine-loving alkylsilanes, this application can better control the spatial distribution of fluoroalkylsilanes and amine-loving alkylsilanes, forming an ordered and spaced structure, thereby achieving high dispersion, high utilization rate and excellent moisture resistance of organic amines.

[0054] In some embodiments, the reaction of the fluoroalkylsilane includes: reacting the fluoroalkylsilane with the oxide support at 80°C to 90°C for 2 h to 6 h; The reaction of loading amine-loving alkylsilanes includes: reacting an oxide support loaded with fluorinated alkylsilanes with amine-loving alkylsilanes at 40℃~70℃ for 1 h~4 h; Organic amines are loaded through impregnation or grafting.

[0055] Reacting fluoroalkylsilanes with oxide supports, and reacting fluoroalkylsilane-supported oxide supports with amine-loving alkylsilanes under the aforementioned conditions, can better promote the reaction. For example, the reaction temperature of fluoroalkylsilanes with oxide supports can be 60°C, 70°C, or 80°C, and the reaction time can be 3 h, 3.5 h, or 4 h, etc.; the reaction temperature of fluoroalkylsilane-supported oxide supports with amine-loving alkylsilanes can be 60°C, 70°C, 80°C, 90°C, or 100°C, and the reaction time can be 2 h, 3 h, 3.5 h, or 4 h, etc.

[0056] Furthermore, in the step of supporting fluoroalkylsilanes, 0.01 M to 0.1 M acetic acid can be used as a catalyst, and in the step of supporting amine-loving alkylsilanes, 1 mM to 10 mM triethylamine or 1 mM to 10 mM imidazole can be used as a catalyst.

[0057] Furthermore, after the impregnation operation of grafting organic amines using the impregnation method is completed, curing at 80℃~110℃ for 2 h~8 h can improve the dispersion stability of the organic amines. For example, the curing temperature of the organic amine can be 80℃, 90℃, 100℃ or 110℃, etc., and the curing time can be 2 h, 5 h or 8 h, etc.

[0058] In some embodiments, the preparation method of the solid amine adsorbent further includes: before loading the fluoroalkylsilane, the oxide support is subjected to surface roughening treatment, the surface roughening treatment including secondary particle stacking, plasma etching or template-assisted etching.

[0059] After secondary particle stacking, plasma etching, or template-assisted etching, micron-scale trenches, cones, microneedles, or dendritic structures are formed on the surface of the oxide support. Preferably, plasma etching is used for surface roughening: one or more reactive gases, such as CF4, CHF3, and SF6, are introduced into a vacuum chamber, and plasma is generated by excitation with a radio frequency power supply. The active groups in the plasma react chemically with the oxide support (such as silicon oxide), while ions bombard the surface of the oxide support under the action of an electric field, providing higher precision and anisotropic etching.

[0060] Thirdly, embodiments of this application provide a CO2 capture process.

[0061] A CO2 capture process, in an air environment or a flue gas environment, uses a solid amine adsorbent as mentioned in the first aspect or a solid amine adsorbent prepared by the preparation method mentioned in the second aspect to capture CO2. In the flue gas environment, NO ≤ 50 ppm, NO2 ≤ 50 ppm, SO2 ≤ 30 ppm, H2O ≤ 15 vol%.

[0062] The technical solution of this application will be further described below with reference to more specific embodiments.

[0063] Example 1 This application provides a method for preparing a solid amine adsorbent, comprising the following steps: Mesoporous silica carrier (DNSN) pretreatment: calcined at 500℃ to remove impurities, then vacuum dried for later use; Supported fluoroalkylsilane: A 0.4 mmol / g solution of 1H,1H,2H,2H-perfluorooctyltriethoxysilane (PFOTES) (using cyclohexane as solvent and containing 0.2 wt.% water) and a mesoporous silica support were reacted at 80 °C for 4 h to form hydrophobic patches. 0.1 M acetic acid was added as a catalyst in this reaction, and the ratio of the 1H,1H,2H,2H-perfluorooctyltriethoxysilane aqueous solution to the mesoporous silica support was 1 g:5 g. Amine-loving alkylsilanes were loaded: a 0.3 mmol / g solution of 3-aminopropyltriethoxysilane (APTES) (using cyclohexane as solvent and containing 0.2 wt.% water) was reacted with a mesoporous silica support loaded with 1H,1H,2H,2H-perfluorooctyltriethoxysilane at 60 °C for 2 h. 5 mM triethylamine was added as a catalyst during the reaction. The ratio of the amount of 3-aminopropyltriethoxysilane solution to the amount of mesoporous silica support loaded with 1H,1H,2H,2H-perfluorooctyltriethoxysilane was 1 g:5 g. Organic amine loading: The mesoporous silica support treated with 3-aminopropyltriethoxysilane was immersed in a pentaethylenehexamine solution at room temperature (25℃) for 1 hour to achieve a loading of 55 wt.%, and then dried at 60℃ for 4 hours to obtain a solid amine adsorbent.

[0064] Example 2 This application provides a method for preparing a solid amine adsorbent, which differs from Example 1 in that: in the step of loading fluoroalkylsilane, 1H,1H,2H,2H-perfluorodecyltrichlorosilane (FDTS) is used instead of 1H,1H,2H,2H-perfluorooctyltriethoxysilane, while the rest remains the same as in Example 1.

[0065] Example 3 This application provides a method for preparing a solid amine adsorbent, which differs from Example 1 in that: in the step of loading amine-loving alkyl silane, N-2-aminoethyl-3-aminopropyltrimethoxysilane (AEAPTMS) is used instead of 3-aminopropyltriethoxysilane, while the rest remains the same as in Example 1.

[0066] Example 4 This application provides a method for preparing a solid amine adsorbent, which differs from Example 1 in that a mesoporous silica support (SBA-15) is used instead of a mesoporous silica support (DNSN). In the step of loading the amine-loving alkylsilane, a mixture of 0.15 mmol / g N-2-aminoethyl-3-aminopropyltrimethoxysilane and 0.15 mmol / g 3-mercaptopropyltrimethoxysilane (MPTMS) was used instead of the 0.3 mmol / g 3-aminopropyltriethoxysilane solution, and the rest remained the same as in Example 1.

[0067] Example 5 This application provides a method for preparing a solid amine adsorbent, which differs from Example 1 in that: before loading fluoroalkylsilane, a surface roughening treatment is performed: CF4 plasma etching is performed at a power of 150 W and a pressure of 0.3 Torr for 5 min to generate nanoscale rough trenches on the surface of the mesoporous silica support. Everything else remains the same as in Example 1.

[0068] Comparative Example 1 This application provides a method for preparing a solid amine adsorbent, which differs from Example 1 in that: a fluoroalkylsilane and an amine-loving alkylsilane are simultaneously loaded. Specifically, after pretreatment of the mesoporous silica support (DNSN), a solution of 1H,1H,2H,2H-perfluorooctyltriethoxysilane and a solution of 3-aminopropyltriethoxysilane are mixed and then reacted with the mesoporous silica support at 80°C for 4 h. 0.1 M acetic acid is added as a catalyst in this reaction; the rest remains the same as in Example 1.

[0069] Comparative Example 2 This application provides a method for preparing a solid amine adsorbent, which differs from Example 1 in that the loading order of fluoroalkylsilane and amine-loving alkylsilane is reversed, with amine-loving alkylsilane being loaded first and then fluoroalkylsilane being loaded; otherwise, the method remains the same as in Example 1.

[0070] experiment I. CO2 Absorption Capacity Test: 1. Under typical direct air capture conditions of 400 ppm CO2, 25℃~30℃, and 40-60%RH, CO2 absorption capacity was tested by continuous adsorption at 25℃ for 20 h~24 h. The test results are CO2 absorption capacity (1).

[0071] 2. Under simulated high humidity flue gas conditions (CO2 in the flue gas is 15 vol%, humidity is 80%RH, temperature is 70℃, and the concentration of acidic impurities in the other impurity gases should be controlled below 50 ppmNO, 50 ppmNO2 and 20 ppmSO2), CO2 absorption capacity is tested after continuous adsorption at 60℃ for 60 min. The test result is CO2 absorption capacity (2).

[0072] II. Cyclic Stability Test After adsorption under simulated high humidity flue gas conditions, desorption was performed at 110℃ for 30 min to complete one adsorption-desorption cycle. The cycle test was performed 20 times, and the CO2 absorption capacity of each test was recorded. (1) Test results were obtained to obtain the cycle stability diagram, and the CO2 adsorption attenuation rate before and after the cycle test was calculated. The calculation formula is as follows: Attenuation rate (%) = (CO2 absorption capacity measured for the first time - CO2 absorption capacity measured for the 20th time) / CO2 absorption capacity measured for the first time.

[0073] The solid amine adsorbents prepared in the above embodiments and comparative examples were used as test samples to test CO2 absorption capacity. The test results are shown in Table 1.

[0074] Table 1

[0075] As can be seen from the data in Table 1, the CO2 absorption capacity (1) and CO2 absorption capacity (2) of each embodiment of this application are high and the decay rate is low, indicating that the adsorption performance and cycle stability of the solid amine adsorbent of this application are excellent.

[0076] Furthermore, by comparing the data of Example 1 and Comparative Example 1 in Table 1, it can be seen that the CO2 absorption capacity (1) and CO2 absorption capacity (2) measured in Example 1 under typical direct air capture and high humidity flue gas conditions are significantly higher than those in Comparative Example 1, and the attenuation rate is significantly lower than that in Comparative Example 1. This proves that by controlling the loading order of fluoroalkylsilane and amine-loving alkylsilane, so that fluoroalkylsilane and amine-loving alkylsilane form a specific distribution on the surface of the oxide carrier, the CO2 absorption effect under direct air capture and high humidity flue gas can be effectively improved, and the cycle stability of CO2 absorption can be improved, thereby effectively suppressing the attenuation rate.

[0077] A comparison of the data from Example 1 and Comparative Example 2 shows that by first loading fluoroalkylsilanes and then loading amine-loving alkylsilanes, a structure can be formed in which amine-loving alkylsilanes are dispersed between adjacent fluoroalkylsilanes. Reversing the loading order is detrimental to the formation of this specific structure, resulting in the CO2 absorption capacity (1) and CO2 absorption capacity (2) of the prepared solid amine adsorbent measured under typical direct air capture and high humidity flue gas conditions being significantly lower than those of Example 1, and even lower than those of Comparative Example 1. The organic amines also cannot form a uniform dispersion on the surface of this solid amine adsorbent, leading to a decrease in the cycle stability of CO2 absorption and an increase in the decay rate.

[0078] The technical solutions disclosed in the embodiments of this application have been described in detail above. Specific examples have been used in this article to illustrate the principles and implementation methods of this application. The description of the above embodiments is only for the purpose of helping to understand the technical solutions and core inventive points of the embodiments of this application. At the same time, for those skilled in the art, there will be changes in the specific implementation methods and application scope based on the ideas of this application. Therefore, the content of this specification should not be construed as a limitation of this application.

Claims

1. A solid amine adsorbent, characterized in that, The invention includes a hydroxyl-containing oxide support, wherein a fluoroalkylsilane and an amine-loving alkylsilane are loaded on the surface of the oxide support, wherein the fluoroalkylsilane has at least 4 more carbon atoms than the amine-loving alkylsilane, and the amine-loving alkylsilane is distributed between adjacent fluoroalkylsilanes. The oxide support surface is also loaded with an organic amine, and the organic amine forms an adsorption bond with the amine-loving alkylsilane.

2. The solid amine adsorbent according to claim 1, characterized in that, The fluoroalkylsilane has 8 to 22 carbon atoms, and the amine-loving alkylsilane has 1 to 6 carbon atoms.

3. The solid amine adsorbent according to claim 2, characterized in that, The fluoroalkylsilanes include one or a combination of two of 1H,1H,2H,2H-perfluorooctyltriethoxysilane and 1H,1H,2H,2H-perfluorodecyltrichlorosilane. The amine-affinity alkylsilane includes amine-affinity alkylsilanes and / or amine-reactive alkylsilanes, wherein the amine-affinity alkylsilane includes one or a combination of two of 3-aminopropyltriethoxysilane and N-2-aminoethyl-3-aminopropyltrimethoxysilane; The amine-reactive alkylsilane includes one or a combination of two of 3-glycidyl etheroxypropyltriethoxysilane and 3-mercaptopropyltrimethoxysilane; The oxide support includes one or more of the following: silicon oxide support, aluminum oxide support, and titanium oxide support.

4. The solid amine adsorbent according to claim 1, characterized in that, The loading of the fluoroalkylsilane is 2 wt.% to 8 wt.%, and the loading of the amine-loving alkylsilane is 1 wt.% to 6 wt.%.

5. The solid amine adsorbent according to claim 1, characterized in that, The oxide carrier surface has micron-level grooves, cones, microneedles or dendritic structures, and the roughness factor of the oxide carrier surface is 10~500.

6. The solid amine adsorbent according to any one of claims 1-5, characterized in that, The organic amine loading is 20 wt.% to 65 wt.%. and / or; The organic amine includes one or more combinations of polyethyleneimine, pentaethylenehexamine, and tetraethylenepentamine.

7. A method for preparing a solid amine adsorbent, characterized in that, The method for preparing the solid amine adsorbent according to any one of claims 1-6 comprises the following steps: The fluoroalkylsilane is loaded onto the surface of the oxide support, followed by the loading of the amine-loving alkylsilane; The organic amine is then loaded and adsorbed between the organic amine and the amine-loving alkylsilane to obtain the solid amine adsorbent.

8. The method for preparing the solid amine adsorbent according to claim 7, characterized in that, The reaction of loading the fluoroalkylsilane includes: reacting the fluoroalkylsilane with the oxide support at 60°C to 80°C for 3 to 4 hours; The reaction of loading the amine-loving alkylsilane includes: reacting the oxide support loaded with the fluoroalkylsilane with the amine-loving alkylsilane at 60°C to 100°C for 2 h to 4 h; The organic amine is loaded by impregnation or grafting.

9. The method for preparing the solid amine adsorbent according to claim 7, characterized in that, The method for preparing the solid amine adsorbent further includes: before the step of loading the fluoroalkylsilane, subjecting the oxide support to surface roughening treatment, wherein the surface roughening treatment includes secondary particle stacking, plasma etching, or template-assisted etching.

10. A CO2 capture process, characterized in that, In an air or flue gas environment, CO2 is captured using the solid amine adsorbent as described in any one of claims 1-6 or the solid amine adsorbent prepared by the preparation method as described in any one of claims 7-9. In the flue gas environment, NO ≤ 50 ppm, NO2 ≤ 50 ppm, SO2 ≤ 30 ppm, and H2O ≤ 15 vol%.

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