Aziridine or azetidine modified amine sorbents, systems containing the sorbents, and methods of using the sorbents

Abstract

The present disclosure provides adsorbents and contactors, methods of using the adsorbents and contactors to capture CO, structures including the adsorbents, and systems and devices that use the adsorbents and contactors to capture CO. In one aspect, the present disclosure provides adsorbents comprising a CO-affine phase and a support. The present disclosure provides adsorbents and contactors comprising a CO-affine phase and a support, wherein the CO-affine phase comprises a modified amine polymer that is the reaction product of an amine and an aziridine or azetidine.

Description

[Technical Field]

[0001] Claiming priority to related applications (cross-reference to related applications) This application claims priority to the co-pending U.S. provisional application "SORBENTS, SYSTEMS INCLUDING SORBENTS, AND METHODS USING THE SORBENTS," having Serial No. 63 / 431,512, filed December 9, 2022, which is incorporated herein by reference in its entirety. [Background technology]

[0002] Greenhouse gases trap heat in the atmosphere, and carbon dioxide (CO2) is one of the main greenhouse gases. CO2 is emitted through human-related activities such as transportation, electricity, industry, and agriculture. In particular, CO2 emissions occur through the burning of fossil fuels, solid waste, and wood, as well as the production of cement and other materials. One way to reduce the amount of CO2 in the atmosphere is to capture it using materials that have an affinity for CO2. Materials that can effectively capture CO2 are needed. Summary of the Invention

[0003] The present disclosure provides adsorbents and contactors, methods of using the adsorbents and contactors to capture CO2, structures including the adsorbents, and systems and devices that use the adsorbents and contactors to capture CO2.

[0004] In one embodiment, the present disclosure provides an adsorbent comprising a CO2-affine phase and a support, wherein the CO2-affine phase comprises the reaction product of an amine with an aziridine or azetidine. In one embodiment, the CO2-affine phase comprises a structure selected from at least one of the following structures, wherein R x is a substituent. TIFF2026503370000002.tif24154 wherein R1, R2, R3, R4, R5, R6, and R7 are each independently selected from a hydrogen atom, hydroxide, linear or branched alkyl, alkanol, alkoxy, alkyl halide, halide, aldehyde, ketone, carboxylic acid, ester, amine, sulfone, phosphine, aryl, aryloxy, aryl halide, benzyl, phenol, or heteroaryl, and the like; and wherein R' is each independently selected from a hydrogen atom, alkyl, alkoxy, alkyl halide, aryl, benzyl, phenyl, phenol, amine, heteroaryl, or nitroimidazole.

[0005] In one aspect, the present disclosure provides a contactor comprising a structure and an adsorbent as described above or herein.

[0006] In one aspect, the disclosure provides a system for capturing CO2 from a gas, optionally wherein the gas is ambient air, comprising: a first apparatus configured to introduce the gas to an adsorbent or contactor as described above or herein to bind the CO2 to the adsorbent; a second apparatus configured to heat the adsorbent containing the bound CO2 to at least a first temperature to release the CO2; and a third apparatus configured to collect the released CO2.

[0007] In one aspect, the disclosure provides a method for capturing CO from a gas, optionally wherein the gas is ambient air, comprising: introducing the ambient air to a sorbent as described above or herein to bind CO to the sorbent; heating the sorbent to at least a first temperature to controllably release CO; and collecting the CO in a collection device.

[0008] In one aspect, the present disclosure provides a system for carrying out the methods described above or herein. [Brief explanation of the drawings]

[0009] Further aspects of the present disclosure will be more readily understood from a consideration of the following detailed description of various embodiments thereof, taken in conjunction with the accompanying drawings.

[0010] [Figure 1A] FIG. 1A shows a schematic diagram of how the amine moiety binds with CO2 to form a carbamate.

[0011] [Figure 1B] Figure 1B is a schematic diagram of an adsorbent system consisting of a support and a CO2-affine phase, which together comprise the adsorbent.

[0012] [Figure 2] FIG. 2 is a schematic diagram of a honeycomb monolith contactor constructed from a substrate and an adsorbent washcoat.

[0013] [Figure 3A] [Figure 3B] Figures 3A and 3B show the H-NMR spectra of PEI (Figures 3A and 3B, top), polymerized azetidine (Figure 3A, middle) and 3-fluoroazetidine (Figure 3B, center), and PEI reacted with azetidine (Figure 3A, bottom) and 3-fluoroazetidine (Figure 3B, bottom).

[0014] [Figure 4A] [Figure 4B] Figures 4A and 4B show mass loss curves for adsorbents made with improved CO2-philic phases containing PEI reacted with (Figure 4A) azetidine and (Figure 4B) 3-fluoroazetidine during exposure to dilute air at increasing temperatures from room temperature to 900 °C. [Figure 5]Figure 5 shows transient mass change profiles from TGA CO adsorption tests using improved adsorbents containing PEI reacted with azetidine, all supported on mesoporous alumina, at 10% CO and a dew point of 6-8 °C. Data for the adsorbent using PEI are also shown for reference. Data are reported as CO capacity (mmol CO / g adsorbent) and are not normalized by variation in N content between adsorbents. [Figure 6A] [Figure 6B] [Figure 6C] [Figure 6D] Figures 6A-6D show the degree of oxidation of PEI over time (oxidation degree) as determined via differential scanning calorimetry (DSC) as described herein and in references (solid line, DSC) and via the decrease in amine efficiency (data points, A-E) at (Figure 6A) 5%, (Figure 6B) 17%, and (Figure 6C) 30% O2 concentrations, and (Figure 6D) the degree of oxidation at various PEI pore fillings. Figure adapted from Nezam et al., ACS Sustainable Chem Eng., 2021, 9, 8477-8486. [Figure 7] Figure 7 shows the transient oxidation curves of modified CO2 adsorbents containing PEI and PEI reacted with azetidine tested at 137.5 °C under 17% O2, balance N2, all adsorbents in mesoporous alumina. [Figure 8] FIG. 8 shows the structures of aziridines and azetidines that can be reacted with amines to form improved CO2-philic phases. DETAILED DESCRIPTION OF THE INVENTION

[0015] Embodiments of the present disclosure provide adsorbents and contactors, methods of using the adsorbents and contactors to capture CO, structures including the adsorbents, and systems and devices that use the adsorbents and contactors to capture CO. In one aspect, the present disclosure provides an adsorbent including a CO-philic phase (e.g., a modified amine polymer that is the reaction product of an amine with an aziridine or azetidine) and a support. The disclosed methods, systems, adsorbents, and contactors may be advantageous over current technology because they are relatively robust, particularly because they reduce the cost of capturing CO from ambient air. In one aspect, the present disclosure provides an adsorbent having an improved CO-philic phase (e.g., a modified amine polymer that is the reaction product of an amine with an aziridine or azetidine) that has high resistance to oxidation.

[0016] Before the present disclosure is described in greater detail, it is to be understood that this disclosure is not limited to particular embodiments described, as such may, of course, vary. It is also to be understood that the terminology used herein is for the purpose of describing particular embodiments only, and is not intended to be limiting, as the scope of the present disclosure will be limited only by the appended claims.

[0017] Where a range of values ​​is provided, unless the context clearly dictates, it is understood that each intervening value, to the nearest tenth of the lower limit, ranges between the upper and lower limits of that range, and any other stated or intervening value, is encompassed within the disclosure. The upper and lower limits of these smaller ranges may independently be included in the smaller ranges and are also encompassed within the disclosure, subject to any specifically excluded limit in the stated range. Where the stated range includes one or both of the limits, ranges excluding either or both of those included limits are also included in the disclosure.

[0018] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this disclosure belongs. Although any methods and materials similar or equivalent to those described herein can also be used in the practice or testing of this disclosure, the preferred methods and materials are now described.

[0019] As will be apparent to those skilled in the art upon reading this disclosure, each of the individual embodiments described and illustrated herein has distinct components and features that may be readily separated from or combined with the features of any of the other several embodiments without departing from the scope or spirit of the disclosure. Any described method can be carried out in the order of events described or in any other order that is logically possible.

[0020] Embodiments of the present disclosure employ, unless otherwise indicated, techniques of chemistry, materials science, mechanical engineering, and the like, which are within the skill of the art.

[0021] The following examples are put forth to provide those of ordinary skill in the art with a complete disclosure and description of how to practice the methods and use the probes disclosed and claimed herein. Efforts have been made to ensure accuracy with respect to numbers (e.g., amounts, temperatures, etc.), but some errors and deviations should be accounted for. Unless otherwise indicated, parts are parts by volume, temperature is in °C, and pressure is at or near atmospheric. Standard temperature and pressure are defined as 20 °C and 1 atmosphere.

[0022] Before describing embodiments of the present disclosure in detail, it is to be understood that, unless otherwise indicated, the present disclosure is not limited to particular materials, reagents, reactants, manufacturing processes, etc., as such may vary. It is also to be understood that the terminology used herein is for the purpose of describing particular embodiments only, and is not intended to be limiting. The present disclosure may allow steps to be carried out in different order, where this is logically possible.

[0023] It should be noted that as used herein and in the appended claims, the singular forms "a," "an," and "the" include the plural unless the context clearly dictates otherwise. Thus, for example, reference to a "compound" includes a plurality of compounds. In this specification and the claims that follow, reference will be made to a number of terms that shall be defined to have the following meanings unless a contrary intention is apparent.

[0024] The present disclosure provides adsorbents (also referred to herein as "adsorbents" or "sorbents") and contactors, methods of using the adsorbents and contactors to capture CO, structures including the adsorbents, and systems and devices that use the adsorbents and contactors to capture CO. In one aspect, the present disclosure provides an adsorbent comprising a CO-philic phase and a support. The present disclosure relates to several types of adsorbents and structures described below and herein.

[0025] In one aspect, the present disclosure provides an adsorbent and contactor comprising a CO2-affine phase and a support, wherein the CO2-affine phase comprises a modified amine polymer that is the reaction product of an amine with an aziridine or azetidine, the reaction product also being described herein. In one aspect, the modified amine polymer maintains a high CO2 capacity compared to an unmodified amine polymer. In one aspect, an adsorbent having a modified amine polymer exhibits less loss in CO2 capture capacity after oxidative exposure compared to an adsorbent made with an unmodified amine polymer, thereby producing an improved CO2-affine phase with a longer commercial life compared to a CO2-affine phase that does not involve reaction with an aziridine or azetidine.

[0026] In one embodiment, modified amine polymers modified by reaction with aziridine or azetidine produce a CO2-philic phase with a shell of amine-containing moieties that can impart additional stability or productivity to the base amine polymer. This allows for tuning of stability and productivity. Furthermore, in the adsorbent (i.e., CO2-philic phase and support), the amine polymer contacts the surface of the support. Reaction of the amine polymer with aziridine or azetidine allows for rational tuning of the polymer shell, which can be specifically designed for interaction with the surface of the support.

[0027] A structured support, also called a formed support or structure, refers to a support that has been formed into a structure that is solid at standard conditions. The support may also be unstructured at standard conditions, having a powder-like consistency. When a support is referred to without reference to a structure, formation, or formed or structured, it can refer to either a structured or unstructured support.

[0028] The structured support can take the form of a homogeneous solid (e.g., consisting primarily of the support, but also containing components that allow it to remain a stable object under standard conditions), or as a coating on a substrate, whereby the substrate has a different composition from the coating and provides mechanical stability to the coating.

[0029] It can be beneficial to utilize a structured support having a CO2-affine phase as a contactor in a process for removing CO2 from a gas stream, such as ambient air. The contactor provides a geometry for the CO2-affine phase that allows optimization of considerations such as pressure drop, throughput, and / or mass transfer rate. An active or structured support refers to a support or structured support that contains a CO2-affine phase at a specific loading within its mesopore volume and / or on its surface. The specific loading of the CO2-affine phase is determined by the mesopore volume of the support or structured support itself and is expressed as the percentage of the mesopore volume occupied by the CO2-affine phase. The specific loading of the CO2-affine phase may vary for different activated supports, structured supports, or contactors (i.e., adsorbents), or when the activated supports, structured supports, or contactors (i.e., adsorbents) are deployed in specific climates or environments. The specific loading level applied to the support must be precisely controlled.

[0030] The CO2-affinity phase includes a CO2-binding molecule. The CO2-binding molecule includes a CO2-binding moiety. The CO2-binding molecule can be an amine or an amine polymer, such as the modified amine described herein. The amine or amine polymer (e.g., the modified amine and / or used to form the modified amine) can contain primary amines, secondary amines, tertiary amines, or any combination of primary, secondary, and tertiary amines. The amine polymer can be branched, hyperbranched, dendritic, or linear. The CO2-binding moiety is an amine moiety on the amine molecule or polymer (e.g., the modified amine). The amine moiety can interact with CO2 to form a carbamate, carbonate, or bicarbonate species. Figure 1A shows a schematic diagram of how the amine moiety binds CO2 to form a carbamate.

[0031] A primary amine is defined as having the chemical structure -NH2R1, where R1 is an alkyl group such as CH2 or CH3. A secondary amine is defined as having the chemical structure -NHR1R2, where R1 and R2 are independently selected from alkyl groups such as CH2 or CH3. A tertiary amine is defined as having the chemical structure -NR1R2R3, where R1, R2, and R3 are independently selected from alkyl groups such as CH2 or CH3.

[0032] Linear amine polymers can be defined as containing only primary amines, only secondary amines, or both primary and secondary amines. The ratio of secondary amines to primary amines can be about 0.5 to 10,000. In one embodiment, the linear amine polymer can have a molecular weight of about 100 to 100,000 g / mol, about 200 to 30,000 g / mol, or about 600 to 5,000 g / mol.

[0033] Branched amine polymers can be defined as containing any number of primary amines, secondary amines, and tertiary amines that do not overlap with linear or dendritic amine polymers. The ratio of primary, secondary, and tertiary amines can be about 10:80:10 to 60:10:30, about 60:30:10 to 30:50:20, or about 45:45:10 to 35:45:20. As will be appreciated by those skilled in the art, the chemical structure of branched amine polymers can vary widely and can be quite complex. In one embodiment, the branched amine polymer can have a molecular weight of about 100 to 100,000 g / mol, about 200 to 30,000 g / mol, or about 600 to 5,000 g / mol.

[0034] Dendritic amine polymers can be defined as containing only primary and tertiary amines, where the repeating units are arranged in a manner that is necessarily symmetrical in at least one plane passing through the center (core) of the molecule, where each polymer branch is terminated by a primary amine, and where each branch point is a tertiary amine. The core or central bond is the same as the branched amines (e.g., an ethyleneimine core and ethyleneimine branches, a propyleneimine core and propyleneimine branches). The primary to tertiary ratio can be about 1 to 3. In one embodiment, the dendritic amine polymer can have a molecular weight of about 100 to 100,000 g / mol, about 200 to 30,000 g / mol, or about 280 to 3,000.

[0035] Hyperbranched amine polymers can be defined as having a chemical structure similar to that of dendritic amine polymers, but containing defects in the form of secondary amines (e.g., linear subsections that would be present in branched polymers) in such a way as to provide a random chemical structure instead of a symmetrical one. Hyperbranched amine polymers do not overlap with branched amine polymers or dendritic polymers. In the hyperbranched chemical structure, the ratio of primary to secondary to tertiary can be about 65:5:30 to 30:10:60. In one embodiment, the hyperbranched amine polymer can have a molecular weight of about 100 to 100,000 g / mol, about 200 to 30,000 g / mol, or about 600 to 10,000 g / mol.

[0036] In one embodiment, linear, hyperbranched, and branched amine polymers have secondary amines and no dendritic amines, which can be advantageous because secondary amines bind CO2 strongly.

[0037] In one aspect, the amine polymer can be a polystyrene-divinylbenzene polymer functionalized with amines such as polyethyleneimine, polypropyleneimine, polyallylamine, polyvinylamine, polyglycidylamine, alkylbenzylamine moieties, or other amine polymers, where each can be branched, hyperbranched, dendritic, or linear.

[0038] In one embodiment, the size (e.g., length, molecular weight), amount (e.g., number of distinct amine polymers), and / or type of amine polymer can be selected based on the desired characteristics of the porous support (e.g., CO adsorption, regeneration properties, oxidative stability, loading, etc.).

[0039] In one aspect, the modified amine polymer can contain a primary amine, a secondary amine, a tertiary amine, or a mixture of any combination of primary, secondary, and tertiary amines, each of which is defined above. The modified amine polymer can be branched, hyperbranched, dendritic, or linear, each of which is defined above.

[0040] In one embodiment, the modified amine polymer can be primary or secondary prior to reaction, e.g., to form a secondary or tertiary amine. Illustrative structures are shown below, where R x is a substituent. TIFF2026503370000003.tif58148 In one embodiment, R1, R2, R3, R4, R5, R6, and R7 can each independently be a hydrogen atom, hydroxide, linear or branched alkyl, alkanol, alkoxy, alkyl halide, halide, aldehyde, ketone, carboxylic acid, ester, amine, sulfone, phosphine, aryl, aryloxy, aryl halide, benzyl, phenol, heteroaryl, etc., and combinations thereof. In one embodiment, R1, R2, R3, R4, R5, R6, and R7 can each independently be a linear or branched alkyl or alkyl halide. In one embodiment, R1, R2, R3, R4, R5, R6, and R7 can each independently be an alkanol or alkoxy. In one embodiment, R1, R2, R3, R4, R5, R6, and R7 can each independently be an aldehyde, ketone, carboxylic acid, ester, amine, sulfone, or phosphine. In one embodiment, R1, R2, R3, R4, R5, R6, and R7 can each independently be an aryl, aryloxy, aryl halide, benzyl, phenol, or heteroaryl. In one embodiment, each R' can be independently selected from a hydrogen atom, an alkyl, an alkoxy, an alkyl halide, an aryl, benzyl, phenyl, phenol, an amine (e.g., an alkyleneimine (C2-C8) such as ethyleneimine and propyleneimine), a heteroaryl, nitroimidazole, or the like, and combinations thereof. In one embodiment, each R' can be independently selected from an alkyl or an alkyl halide. In one embodiment, each R' can be independently selected from an aryl, benzyl, phenyl, phenol, or heteroaryl. In one embodiment, each R' can be independently selected from amines (e.g., alkyleneimines (C2-C8) such as ethyleneimine and propyleneimine). In one embodiment, each R' can be independently selected from nitroimidazoles.

[0041] In one aspect, modification of the amine polymer by reaction with aziridine or azetidine reduces the total number of primary amines in the modified amine polymer system.

[0042] In one aspect, the modified amine polymer can be a modified polyethyleneimine, a modified polypropyleneimine, a modified polyallylamine, a modified polyvinylamine, a modified polyglycidylamine, a modified polystyrene-divinylbenzene polymer functionalized with amines such as alkylbenzylamine moieties, or other modified amine polymers, where each modified amine polymer can be branched, hyperbranched, dendritic, or linear.

[0043] In one aspect, the percentage of amines modified as described herein can be about 0.001 to 1, about 0.01 to 1, or about 0.1 to 1, or about 0.5 to 1 of all primary and secondary amines in the amine polymer, where a percentage of 1 means all primary and secondary amines, or about 0.01 to 0.5 percentage of the amines in the amine polymer.

[0044] Without intending to be bound by theory, CO2-affinity phases modified by reaction with aziridine and azetidine allow for the rational introduction of substituents onto the amine polymer to tailor the properties of the CO2-affinity phase. For example, bulky substituents such as phenyl or substituted phenyl can be used to sterically hinder oxygen attack during oxidation reactions. Furthermore, substituents can be used to chemically stabilize the amine polymer from oxidation. Chemical stabilization can be achieved by introducing electron-donating or electron-withdrawing substituents onto the amine polymer. The amount, type, and mixture of modifiers can be adjusted and varied to achieve the desired properties of the CO2-affinity phase. Tuning the CO2-affinity phase can result in one or a combination of the following effects on the improved CO2 adsorbent: increased lifetime due to a reduced oxidative decomposition rate, increased amine efficiency of the adsorbent, increased CO2 swing capacity of the adsorbent during the adsorption / desorption process, and increased equilibrium capacity of the adsorbent.

[0045] In one aspect, it may be advantageous to improve the stability of the CO-affinity phase to process conditions associated with the use of the adsorbent in a CO separation process, particularly during adsorbent regeneration (a process cycle in which the adsorbent is subjected to elevated temperatures to remove bound CO). It would also be advantageous to improve the stability of the CO-affinity phase to conditions associated with storage of the adsorbent when the adsorbent is not utilized in the process or plant. Adsorbents having a CO-affinity phase with improved stability with respect to process conditions, including process conditions involving adsorbent regeneration, storage, or both adsorbent regeneration and storage, would be beneficial.

[0046] Evaluating the oxidative stability of a material in an environment containing oxygen and CO2 is beneficial due to the fact that during the regeneration process, desorbed CO2, in addition to oxygen at high temperatures, is present in various concentrations and may affect the stability of the material. Separately, evaluating the oxidative stability of a material in oxygen only (air) is a useful method for assessing the shelf life of a material when stored at ambient conditions.

[0047] As described above, the CO2-affinity phase (e.g., CO2-binding molecule) can be homogeneous or heterogeneous. When the CO2-affinity phase is heterogeneous, the CO2-binding molecule can be present in various ways. For example, the CO2-binding molecule can be applied to or incorporated into the support, e.g., onto the surface of the pores of the support, to form a layer of the CO2-affinity phase. In another embodiment, used independently of or in combination with other embodiments, such as those described above, the CO2-binding molecule can be used to form part or all of the support, where the CO2-affinity phase functions as described herein. Various combinations are contemplated and are part of this disclosure. Additional methods for applying, using, or incorporating a CO2-affinity phase homogeneously and / or heterogeneously are described herein and below.

[0048] As described herein, the adsorbent comprises a CO2-affine phase (e.g., a CO2-binding molecule) and a support. The support comprises a surface (e.g., a surface that can be exposed to CO2-containing gases during normal use and / or that can interact with the CO2-affine phase). The surface can be the surface of a pore and / or other surface with which the CO2-affine phase contacts or interacts.

[0049] In one embodiment, a CO2-affine phase (e.g., a CO2-binding molecule) can be disposed on and / or within a support to form a sorbent. The CO2-affine phase can be disposed on the surface of the support, and / or within the pores of the support, and / or on the exterior surface of the support, or any combination thereof. In one embodiment, the CO2-affine phase can be a coating on the surface of a porous material, a monolayer on the surface of a porous material, a self-assembled monolayer on the surface of a porous material, a bulk phase within the pores of a porous material, a coating on the exterior surface of a porous material, etc.

[0050] In one embodiment, the support can be made from one or more types of materials such as ceramic, metal, metal oxide, plastic, cellulose, carbon, zeolite, metal organic framework (MOF), porous organic framework (POF), covalent organic framework (COF), polymer of intrinsic microporosity (PIM), polymer, fibrous cellulose, glass fiber, boron nitride fiber, etc. In another embodiment, the support can be made from a material that also includes a CO2-philic phase.

[0051] The metal oxide support can be selected from cordierite, alumina (e.g., γ-alumina, θ-alumina, δ-alumina), cordierite-α-alumina, silica, aluminosilicates, zirconia, germania, magnesia, titania, hafnia, silicon nitride, zircon mullite, spodumene, alumina-silica magnesia, zircon silicate, sillimanite, magnesium silicate, zircon, petalite, and combinations thereof. In cases where the oxide contains a formal charge, the charge can be balanced with appropriate counterions, such as cations of NR, Na, K, Ca, Mg, Li, H, Rb, Sr, Ba, Cs, or anions including phosphate, phosphite, sulfate, sulfate, nitrate, nitrite, chloride, bromide, etc. The metal oxide can contain dopants such as zirconium, iron, tin, silicon, and titanium, and combinations thereof. It is known that metal oxides can contain acid, basic, and neutral sites on their surfaces, and dopants can change the amount and strength of the acid and basic sites on the surface.

[0052] In one aspect, the polymeric support can be a polymer and / or copolymer of polyolefin, polyester, polyurethane, polycarbonate, polyetheretherketone, polyphenylene oxide, polyethersulfone, melamine, polyamide, polyvinylbenzene, polystyrenedivinylbenzene, polyurethane, polyacrylate, polystyrene, polyacrylonitrile, polyimide, polyfurfural alcohol, phenol furfuryl alcohol, melamine formaldehyde, resorcinol formaldehyde, cresol formaldehyde, phenol formaldehyde, polyvinyl alcohol dialdehyde, polycyanurate, polyacrylamide, various epoxies, agar, and agarose, or combinations thereof.

[0053] The support can be porous (e.g., macroporous, mesoporous, microporous, or a mixture thereof (e.g., a macroporous surface can include mesopores and / or micropores within one or more macropores, a mesoporous surface can include micropores, etc.)). In one embodiment, the porous structure is mesoporous. The pores can extend throughout the porous structure or porous layer, or can extend only to a certain depth. The macropores of the porous structure can have pores with diameters of about 100 nm to 10,000 nm, lengths of about 500 nm to 100,000 nm, and volumes of 0.2 to 1 cc / g. The mesopores of the porous structure can have pores with diameters of about 5 nm to 100 nm, lengths of about 10 nm to 10,000 nm, and volumes of 0.1 to 2 cc / g. The micropores of the porous structure can have pores with a diameter of about 0.5 to 5 nm, a length of about 0.5 nm to 1000 nm, and a volume of about 0.1 to 1 cc / g.

[0054] The support may be porous and may have a porosity of at least 90%, at least 85%, at least 80%, at least 75%, at least 70%, at least 65%, at least 60%, or about 60-90%. In some embodiments, the support may have a porosity of at least about 1 mm. 2 / g or more, about 10m 2 / g or more, about 100m 2 / g or more, approximately 150m 2 / g or more, about 200m 2 / g or more, or approximately 250m 2 / g or more, approximately 500m 2 / g or more, about 1000m 2 / g or more.

[0055] In one embodiment, the CO2-affinity phase (e.g., CO2-binding molecule) may be physically impregnated into the pores of the interior volume of the porous structure, may not be covalently bonded to the interior surface of the pores of the porous structure, may be grafted (e.g., directly or indirectly covalently bonded) to the interior surface of the pores of the porous structure, or a combination thereof. In one embodiment, the CO2-affinity phase (e.g., CO2-binding molecule) may be covalently bonded (e.g., directly to the surface or via a linker group) to the surface of a material that may comprise the interior surface of the pores for the porous layer or porous structure. In one aspect, covalent bonding can be achieved using techniques known in the art for attaching adsorbents. With regard to a CO2-affinity phase (e.g., CO2-binding molecule) that is physically impregnated into the pores of the porous structure and not covalently bonded to the interior surface of the pores of the porous structure, the CO2-affinity phase may be confined within the pores of the support or may not be surface-bound. In yet another embodiment, the CO2-philic phase (e.g., CO2-binding molecule) resides in a plurality of pores (internal volume) of a porous structure ("porous structure" can include a structure having pores on its surface or a structure having a porous layer or coating on the surface of the structure (which may or may not be porous itself), where the CO2-philic phase has a loading of about 10% to 75% by weight of the support. Regarding loading, the loading is determined by thermogravimetric analysis (TGA).

[0056] In one embodiment, the support can include a surface layer on the surface of the support's pores that can bind to the CO2-philic phase. In one aspect, the surface layer can include organically modified moieties (e.g., alkyl groups, amines, thiols, phosphines, etc.) on the surface of the material (e.g., the exterior and / or interior surfaces of the pores). In one embodiment, the surface layer can include surface alkyl groups, amines, thiols, phosphines, etc., and the CO2-philic phase can be directly and / or indirectly covalently bonded (e.g., covalently bonded to a linker that is covalently bonded to the material). In one embodiment, the surface layer can include an organic polymer having one or more of the following groups: alkyl groups, amines, thiols, phosphines, etc. In another embodiment, the structure can be a carbon support, where the carbon support can include one or more of the following groups: alkyl groups, amines, thiols, phosphines, etc.

[0057] In one embodiment, the CO2-philic phase can have a specific loading of about 10-100% of the mesopore volume of the support, or can have a specific loading of about 30-90% of the mesopore volume of the support, or can have a specific loading of about 40-80% of the mesopore volume of the support, or can have a specific loading of about 50-70% of the mesopore volume of the support.

[0058] The processes for making structured supports, formed supports, or structures described above and herein can be used to make any of the structures listed in this and the following paragraphs. The adsorbent comprising the CO2-philic phase and support can be formed into or applied to the structure. In one embodiment, the CO2-philic phase and support can form 100% or less of the structure (e.g., about 10%, about 20%, about 30%, about 40%, about 50%, and about 60%, about 70%, about 80%, about 90%, about 99%, or any combination of ranges therebetween, e.g., about 10-99%, about 10-80%, about 10-50%, about 50-99%, about 50-90%, about 50-80%), where a sufficient amount of adsorbent is present on the surface of the structure to adsorb the desired amount of CO2. In one embodiment, the structure can be a honeycomb, a laminate sheet, a foam, a fiber, a minimal surface solid, a powder tray, a pellet, a powder, or the like, or a combination of two or more of the foregoing.

[0059] In one embodiment, the porosity of the structure can comprise macropores, mesopores, and / or micropores. In one embodiment, the CO2-philic phase is located primarily (e.g., about 40-100%, or about 50-90%, or about 60-80%) within the mesopores of the structure.

[0060] In one aspect, the structure can consist entirely of the adsorbent or can comprise another substrate material, such as a ceramic, a metal, a metal oxide, a plastic, or another material. The structure can be a porous substrate or can include a porous coating over some or all portions of the porous substrate, where the CO2-philic phase can be present in the pores of one or both of the porous substrate and the porous coating.

[0061] If the structure is composed entirely of the adsorbent (e.g., CO2-binding molecule and support), it can be formed, for example, by extrusion, molding, 3D printing, etc. The structure can be formed using a support material that does not contain a CO2-affine phase, or using a support that already has a CO2-affine phase incorporated. If formed without a CO2-affine phase, the CO2-affine phase can be incorporated into the structure by impregnation, grafting, or other functionalization techniques.

[0062] In certain aspects, the support material may be applied to the substrate as a porous coating (also referred to as a "washcoat") on the surface of the substrate. In one embodiment, the porous coating may be a foam, such as a polymer foam (e.g., polyurethane foam, polypropylene foam, polyester foam, etc.), a metal foam, or a ceramic foam. The porous coating may include a metal oxide layer (e.g., a foam, etc.). The metal oxide layer may be, for example, silica or alumina on the surface of the substrate. The porous coating may be present on the surface of the substrate, within the pores or voids of the substrate, or a combination thereof. The porous coating may be about 50 μm to 1500 μm thick, and the pores may be of the dimensions described above and herein.

[0063] In one embodiment, the support material, substrate, and / or structure can be made from a ceramic substrate such as cordierite, alumina (e.g., γ-alumina, θ-alumina, δ-alumina), cordierite α-alumina, silica, aluminosilicate, zirconia, germania, magnesia, titania, hafnia, silicon nitride, zircon mullite, spodumene, alumina-silica magnesia, zircon silicate, sillimanite, magnesium silicate, zircon, petalite, and combinations thereof. The metal or metal oxide structure can be aluminum, titanium, stainless steel, an Fe—Cr alloy, or a Cr—Al—Fe alloy. In cases where the oxide contains a formal charge, the charge can be balanced with appropriate counterions such as cations of NR4, Na, K, Ca, Mg, Li, H, Rb, Sr, Ba, Cs, or anions including phosphate, phosphite, sulfate, sulfate, nitrate, nitrite, chloride, bromide, etc.

[0064] In one embodiment, the support material, substrate, and / or structure may be made from a plastic substrate which may be made from polymers and / or copolymers of polyolefins, polyesters, polyurethanes, polycarbonates, polyetheretherketones, polyphenylene oxides, polyethersulfones, melamine, polyamides, polyvinylbenzene, polystyrene-divinylbenzene, polyurethanes, polyacrylates, polystyrenes, polyacrylonitriles, polyimides, polyfurfural alcohol, phenol furfuryl alcohol, melamine formaldehyde, resorcinol formaldehyde, cresol formaldehyde, phenol formaldehyde, polyvinyl alcohol dialdehyde, polycyanurates, polyacrylamides, various epoxies, agar, and agarose, or combinations thereof.

[0065] In one embodiment, the structure can be a honeycomb structure, such as a honeycomb monolith structure containing channels. The honeycomb structure can have a regular corrugated structure. The honeycomb monolith structure can have a length and width on the order of a few centimeters to several meters, while the thickness can be on the order of a few millimeters to several centimeters or more. In one aspect, the honeycomb monolith structure does not have a fibrous shape. In other words, the honeycomb structure can be a flow-through substrate with open channels defined by channel walls. The channels can have about 50 to about 900 cells per square inch. The channels can have polygonal (e.g., square, triangular, hexagonal, octagonal), sinusoidal, circular, or other cross-sections. Along the length of the channel, the channel can have a configuration that is linear, zigzag, diagonal, or herringbone in shape. The channel length can be from 1 mm to several tens of centimeters, or several hundred centimeters or more. The channels can have perforated or louvered walls. In one embodiment, the adsorbent can be disposed within the pores of the honeycomb structure and / or within the pores of a porous layer on the surface of the honeycomb structure. The honeycomb structure can have a geometric porosity, otherwise known as open surface area, of between 0.3 and 0.95 or between about 0.5 and 0.9.

[0066] In one embodiment, the honeycomb structure may comprise an inlet end, an outlet end, and an interior channel extending from the inlet end to the outlet end. In some embodiments, the honeycomb comprises a plurality of cells extending from the inlet end to the outlet end, the cells being defined by intersecting cell or channel walls.

[0067] In one aspect, the honeycomb structure and / or substrate can be ceramic (e.g., the type manufactured by Corning under the Celcor® trademark) that can be used with adsorbents in accordance with the principles of the present disclosure. The adsorbent can be coated or otherwise immobilized within the pores of the ceramic honeycomb structure and / or in a porous layer on the surface of the ceramic honeycomb structure. In one aspect, the porous coating can include a metal oxide layer, such as silica or alumina, on the surface of the substrate. In one embodiment, the metal oxide layer can be mesoporous and macroporous. The honeycomb monolith can have a depth of 3 inches to 10 feet, or about 3 to 24 inches.

[0068] In one aspect, the structure can be a laminate sheet, which is a structure that includes a one-dimensional wall structure whereby the sheets are stacked together with spaces between each sheet to allow gas to flow between the sheets.

[0069] In one aspect, the structure can be a foam, which is a structure having irregular channel structures surrounded by irregular solid structures that are interconnected such that the foam material is self-supporting.

[0070] In one embodiment, the structure can be a plurality of fibers. Fibers are structures with high aspect ratios and can be arranged in a regular array among themselves when supported at least at one end of the fiber in gas contacting applications. The fibers can be solid or hollow.

[0071] In one aspect, the structure can be a minimum surface solid. Minimum surface solids are structures often used in packings for distillation and adsorption systems to increase the contact area between the material and the fluid. Minimum surface area solids have an average surface area of ​​zero and are geometric shapes, including shapes such as gyroids. A gyroid can be, for example, a sinusoid.

[0072] In one aspect, the structure may be a powder tray. A powder tray is a tray that holds loose powder or pellets of the adsorbent of the present disclosure, thereby forming a structured contactor without the material forming a free-standing structure. Powder trays can be arranged in stacked layers to form sheets, thereby forming a structure similar to a laminate. These layers can be made using flexible sheets, rigid sheets, or other flat surfaces mounted on a rigid frame structure. Powders are loose, free-flowing solids with a characteristic small particle size that provides a powder-like consistency. Pellets are beads, balls, or other compressed structures used to provide structure and surface area to the adsorbent.

[0073] In one aspect, the structure can be a volume of adsorbent particles. The adsorbent particle volumes can be enclosed by one or more walls to maintain the adsorbent contained therein while allowing gas to pass through them. The adsorbent particle volumes can be arranged relative to other adsorbent particle volumes to approximate honeycomb, fiber, or other structured contactors with solids.

[0074] In one aspect, a sorbent (e.g., structure) in the form of a contactor is an efficient embodiment for an effective method for capturing CO from ambient air or other gas mixtures (e.g., flue gas, exhaust gas, natural gas, or other gases containing CO) because structured contactors or contactors can be designed to provide high surface area and low pressure drop for air processes. The contactor can take the form of a honeycomb, laminated sheet, foam, fiber, minimal surface solids, powder tray, pellet, powder, etc., as described, or a combination of two or more of the above.

[0075] Now that embodiments of the adsorbent and structures have been described, details are provided regarding the systems and methods of the present disclosure. The present disclosure provides a method for capturing CO from ambient air or other gas mixtures (e.g., flue gas, exhaust gas, natural gas, or other gases containing CO). The method includes introducing ambient air into an adsorbent (e.g., a structure), heating the adsorbent to at least a first temperature (e.g., about 10-200°C above the normal adsorbent temperature for adsorbing CO) to controllably release CO, and collecting the CO in a CO collector. The temperature increase of the adsorbent can be achieved by contacting the adsorbent with a hot gas, contacting the adsorbent with a hot fluid, contacting the adsorbent with an operating heat exchanger through which a hot fluid or gas passes, heating the walls of a vessel, container, or other containment device containing the adsorbent, or contacting the adsorbent with steam (e.g., the steam may be at a temperature between 60-200°C and may be saturated or superheated). In one aspect, the method may be implemented using the system described below.

[0076] The present disclosure provides systems and devices for capturing CO2 from ambient air or other gas mixtures (e.g., flue gas, exhaust gas, natural gas, or other gases containing CO2) where CO2 removal is important. Generally, the system includes a first device configured to introduce the ambient air or other gas mixture into an adsorbent or contactor, including those described herein. The adsorbent is exposed to the ambient air or other gas mixture for a period of time (e.g., several hours). In certain embodiments, the adsorbent is a honeycomb monolith having an open face area between 0.3 and 0.95 m / s. The first device is configured, for example, to deliver ambient air to the honeycomb monolith at a velocity between 0.25 and 10 m / s. After a desired period of time, a second device is configured to heat the adsorbent containing the bound CO2 to at least a first temperature to release the CO2. The second device of the system is operable to desorb the CO2 by the adsorbent. The second device can include components to support a temperature swing, pressure swing, vapor swing, concentration swing, combinations thereof, or other dynamic process to desorb CO2. In one embodiment, a vapor swing process can include exposing the sorbent to steam, where the temperature of the steam is between about 60°C and 150°C and the pressure of the steam is between about 0.2 bar and 5 bar. The third device is configured to collect the released CO2. The system can be operated such that the sorbent adsorbs and desorbs CO2 efficiently and cost-effectively.

[0077] Example Separately, the removal of CO2 from ambient air via engineered chemical processes, known as direct air capture (DAC), has emerged as an important environmental technology for climate change mitigation. DAC is a technology that can remove CO2 from the atmosphere and provide negative emissions. However, current DAC technologies are expensive, thereby limiting their deployment. Therefore, improvements in DAC technology are needed. Many DAC technologies rely on solid sorbent materials as a medium for separating CO2 from air. These sorbents are generally applied in a temperature swing process, where CO2 from the air binds to their internal sites at low temperatures, and then, at high temperatures, the CO2 is released into a concentrated product that can be sequestered or sold. Many DAC sorbents utilize amines to bind CO2 in this manner. Certain types of amines can be effective in binding CO2 from low concentrations (400 ppm) found in air.

[0078] Although some types of amines are effective at binding CO2 from ambient air, they are slowly oxidized in air by ambient oxygen. This effect is exacerbated during process cycles in which the temperature of the adsorbent is increased to remove the bound CO2, thereby producing accelerated oxidative decomposition that shortens the life of the CO2 adsorbent. Therefore, there is a need for adsorbents with improved oxidative stability that are effective at removing CO2 from ambient air.

[0079] Some adsorbents used in DAC processes are composite materials containing a CO2-philic phase (e.g., CO2-binding molecules) distributed within or within a solid material that provides surface area. The CO2-philic phase can be grafted to the solid surface, physically impregnated within the pores of the solid material, or physically supported on the surface of the solid material. The CO2-philic phase of these adsorbents can be an amine or other molecule capable of binding CO2. In some cases, the amine can be, for example, polyethyleneimine, polypropyleneimine, polyallylamine, polyvinylamine, polybutylamine, or other polymeric amines. These polymeric amines can be linear, branched, hyperbranched, dendritic, or some other polymeric form. In other cases, the amine can be a small molecule such as TEPA, TPTA, or others. In other cases, the amine can be an aminosilane. The solid support material can be a metal oxide, carbon, metal, or other structure that can provide sufficient surface area on which the CO2-philic phase is deposited to enable useful CO2 adsorption and desorption capabilities and kinetics. In this way, the solid support material is functionalized with a CO2-philic phase to produce a composite adsorbent.

[0080] The adsorbent may be formed into or incorporated into a macrostructure or contactor to provide advantages in applications such as DAC. Such structures may be honeycomb monoliths, laminated sheets, pellets, or other structures that can provide a high geometric surface area for air or CO2-containing gas to efficiently contact the adsorbent so that the CO2 can bind to the adsorbent.

[0081] Sorbents can be used in processes to capture CO2 from air or various other gas streams, such as flue gas, natural gas, etc. These processes are known as "CO2 capture processes." CO2 capture processes can utilize temperature swing, concentration swing, pressure swing, steam stripping, or other swing techniques to remove CO2 bound to the surface of the sorbent.

[0082] The development of improved CO2 adsorbents utilizing polyethyleneimine, especially for DAC applications, has been relatively limited.

[0083] Having now described embodiments of the present disclosure, the following examples generally describe some additional embodiments of the present disclosure. While embodiments of the present disclosure will be described in conjunction with these examples and the corresponding text and figures, there is no intent to limit the embodiments of the present disclosure to these descriptions. On the contrary, it is intended to cover all alternatives, modifications, and equivalents that fall within the spirit and scope of the embodiments of the present disclosure.

[0084] Example: Schematic showing a support material and an adsorbent with a CO2-affine phase. Figure 1B shows the major components of the adsorbent system. The adsorbent system is composed of a support material and a CO2-affinity phase. In the illustrated schematic, a single CO2-affinity phase is shown incorporated into a single support. The CO2-affinity phase shown is polyethyleneimine (PEI). One known adsorption product of CO2 and PEI is ammonium carbamate. Mesoporous alumina is shown as the support.

[0085] Example: Schematic of a honeycomb monolith structure containing an adsorbent washcoat. Figure 2 shows one embodiment of a honeycomb monolith contactor. Figure 2 illustrates the primary geometric features of a honeycomb monolith, with straight flow-through channels surrounded on all sides by walls. Figure 2 also shows a schematic of a washcoat applied to the wall, which is comprised of a sorbent. The sorbent is comprised of a support material and a CO2-affine phase, such as PEI. This example shows a cordierite substrate, an alumina support, and a PEI CO2-affine phase.

[0086] Example: Preparation of 3-fluoroazetidine. Azetidine 3-fluoroazetidine was prepared by stirring 1.1155 g of 3-fluoroazetidine hydrochloride with 3.322 equivalents of NaOH (1.3286 g) in 1.5 mL of water at room temperature for 30 minutes, followed by vacuum distillation at room temperature to give 0.75 g of 3-fluoroazetidine (99.9% yield).

[0087] Example: Preparation of an improved CO2-philic phase comprising polyethyleneimine (PEI) reacted with azetidine. Branched PEI MW 800 is available from Sigma Aldrich. Azetidine is azetidine and 3-fluoroazetidine.

[0088] PEI reacted with azetidine. PEI (0.2 g) was dissolved in a methanol solution, followed by the addition of 0.2 g of azetidine, followed by 0.094 mL of 70% HClO. The mixture was stirred at 80 °C for 70 hours to allow the azetidine to react with the PEI. The solvent was removed from the reaction mixture, and then 30 mL of Ambersep 900 and 10 mL of water were added. The reaction mixture was then stirred at room temperature for 24 minutes. The Ambersep 900 was then removed via filtration, and the filtrate was concentrated and dried under vacuum at 50 °C for 12 hours or more. The resulting polymer is called PEI-b-PPI.

[0089] PEI was reacted with 3-fluoroazetidine. PEI (0.2 g) was dissolved in a methanol solution, followed by the addition of 0.2 g of 3-fluoroazetidine, followed by 0.07 mL of 70% HClO. The mixture was stirred at 80 °C for 90 h to allow the azetidine to react with the PEI. The solvent was removed from the reaction mixture, and then 30 mL of Ambersep 900 and 10 mL of water were added. The reaction mixture was then stirred at room temperature for 24 h. The Ambersep 900 was then removed via filtration, and the filtrate was concentrated and dried under vacuum at 50 °C for 12 h or more. The resulting polymer is called PEI-bF-PPI.

[0090] Impregnation of porous supports: Separately, azetidine-reacted PEI was dissolved in methanol and mixed until homogeneous. Next, mesoporous alumina was dispersed in the azetidine-reacted PEI solution. After stirring for 5 hours or more, the solvent was removed by rotary evaporation, followed by drying in a vacuum oven at 50 °C for 12 hours or more. The mass ratio of alumina to azetidine-reacted PEI was controlled to achieve 40-80% filling of the mesopores of the mesoporous alumina with azetidine-reacted PEI. The resulting composite adsorbent had a powder-like consistency.

[0091] Example: Characterization of improved CO2-philic phases and CO2 adsorbents. Chemical characterization was performed to confirm the properties of the support and the improved CO2-philic phases. Further chemical characterization was performed to confirm that these CO2-philic phases were successfully incorporated into the pores of the mesoporous support to produce improved CO2 adsorbents.

[0092] 1 H NMR studies were performed on PEI and on materials obtained after reaction of PEI with various azetidines to characterize the properties of the obtained materials. To characterize the total amount of organic matter present in the adsorbent, TGA burn-off tests were performed on adsorbents consisting of modified CO₂-philic phases and mesoporous supports. Samples were heated to 900°C under diluted air, and their mass loss was tracked. The total organic matter content was obtained as the mass loss over that temperature interval after removing the contributions of CO₂ and HO lost at lower temperatures.

[0093] Example: PEI and improved CO2-philic phases produced by reaction of PEI with azetidine 1 H NMR spectrum. Figures 3A and 3B show the H NMR spectra of PEI reacted with azetidine and 3-fluoroazetidine, as well as comparisons with unmodified PEI and the polymerized individual azetidines. Comparing the spectra, peaks from PEI and b-PPI or bF-PPI are observed in the resulting reaction polymers, PEI-b-PPI and PEI-bF-PPI, indicating successful synthesis and the desired product.

[0094] Example: TGA burn-off test. Figures 4A and 4B show the mass loss curves during exposure of the materials to diluted air while increasing the temperature from room temperature to 900 °C. The organic loadings of the resulting materials are as follows: PEI-b-PPI - 31.7%, PEI-bF-PPI - 31%.

[0095] Example: Testing in a CO2 adsorption process. To evaluate the effectiveness of the adsorbent for CO2 capture, the adsorbent produced using the improved CO2-affinity phase was tested for CO2 adsorption in a TGA under 10% CO2, 30 °C, and humidity with a dew point of 6-8 °C. The adsorbent was first treated in N2 at 100 °C to desorb bound HO and CO2 before being equilibrated at 30 °C under humidified N2. The gas concentration was then isothermally switched to N2 containing humidified 10% CO2, and the mass change was recorded. To humidify the N2 and 10% CO2 equilibrated N2 gas, the gas was saturated with water vapor at a dew point of 6-8 °C by sparging the gas stream into a water bath held at the corresponding temperature. Under these humidification conditions, it was assumed that no additional moisture was adsorbed during the switch from the humidified N2 stream to the humidified CO2 and N2 streams. Therefore, the mass gain of the material corresponds to CO2 adsorption and can therefore be used to measure the total amount and rate of CO2 adsorption into the material.

[0096] Various improved adsorbents were characterized for CO2 adsorption using this method and compared to a baseline PEI-based adsorbent. The adsorbents were evaluated based on their CO2 capacity, millimoles of CO2 adsorbed per mole of adsorbent present.

[0097] Example: CO2 adsorption capacity at 10% CO2 of improved CO2-philic phases supported on PEI and mesoporous alumina. Figure 5 shows transient TGA CO adsorption curves for adsorbents with improved CO-philic phases made with PEI reacted with azetidine (PEI-b-PPI, 50.8% pore filling) and 3-fluoroazetidine (PEI-bF-PPI, 49% pore filling) compared to unmodified PEI (54% pore filling). Each of the adsorbents is capable of adsorbing CO with varying degrees of performance.

[0098] Example: Oxidative stability testing. The oxidative stability of a material can be examined in several ways. In this study, the oxidative stability of the adsorbent was evaluated by tracking the heat flow generated by the material during exposure to isothermal oxidative conditions using DSC. Here, the adsorbent was first treated in inert gas at 100 °C to desorb bound HO and CO before being equilibrated in inert gas at 137.5 °C for 60 minutes. The gas was then isothermally switched to a 17% O mixture and held until the reaction was complete. This isothermal oxidative environment was maintained for a specified time to measure heat flow and mass loss. To prevent further oxidation, the sample was then cooled to room temperature under N2. During these tests, at each oxidative condition, the DSC measured incremental heat flux, which increased, leveled out, and then decreased to zero. Oxidation was considered complete when the integrated heat flow over 10 minutes changed by less than ±0.01% of the total integrated heat. To determine the extent of oxidation as a function of time, DSC data were converted from mW / mg adsorbent to W / g PEI using the PEI loading measured by TGA burnoff. DSC data were corrected for drift by applying an offset determined by the heat flow value when the DSC curve approached a horizontal line. The total heat generated was calculated by integrating the heat flow over time. The extent of oxidation from DSC was calculated by dividing the integrated heat flow curve by the total heat generated. This method has been previously calibrated using loss of amine efficiency as a way to track the chemical kinetics of oxidative degradation in situ, as shown in Figure 6. Further details of this method and its validation are described in the following papers: Nezam et al., ACS Sustainable Chem Eng., 2021, 9, 8477-8486, and Racicot et al., J. Phys. Chem. C, 2022, 126, 8807-8816, which are incorporated herein by reference. Figure 7 shows the oxidation curves in the presence of air alone for improved CO2 adsorbents utilizing PEI reacted with azetidine (PEI-b-PPI) and 3-fluoroazetidine (PEI-bF-PPI) compared to unmodified PEI supported on mesoporous alumina. It can be seen that the azetidine-reacted PEI can maintain (PEI-bF-PPI) or increase (PEI-b-PPI) the oxidative stability of PEI compared to unmodified PEI. This suggests that certain azetidines may be effective in improving the oxidative stability of amine polymer adsorbents.

[0099] Working Example: FIG. 8 shows the structures of aziridines and azetidines that can be reacted with amines to form improved CO2-philic phases.

[0100] It should be noted that ratios, concentrations, amounts, and other numerical data may be expressed in range format herein. It should be understood that such range format is used for convenience and brevity and, therefore, should be interpreted in a flexible manner to include not only the numerical values ​​explicitly recited as limits of the range, but also all individual numerical values ​​or subranges subsumed within that range, as if each numerical value and subrange were explicitly recited. By way of example, a concentration range of "about 0.1% to about 5%" should be interpreted to include not only the explicitly recited concentration of about 0.1 wt% to about 5 wt%, but also individual concentrations (e.g., 1%, 2%, 3%, and 4%) and subranges (e.g., 0.5%, 1.1%, 2.2%, 3.3%, and 4.4%) subsumed within the stated range. In one embodiment, "about 0" can refer to 0, 0.001, 0.01, or 0.1. In one embodiment, the term "about" can include conventional rounding to the nearest significant digit of a numerical value. Additionally, the expression "about 'x' to 'y'" includes "about 'x' to about 'y'".

[0101] It should be emphasized that the above-described embodiments of the present disclosure are merely possible examples and are set forth solely for a clear understanding of the principles of the present disclosure. Many variations and modifications can be made to the above-described embodiments of the present disclosure without substantially departing from the spirit and principles of the present disclosure. All such modifications and variations are intended to be included within the scope of the present disclosure herein.

Claims

1. An adsorbent comprising: ２ - an affinity phase and a support, ２ - The affinity phase is an adsorbent comprising the reaction product of an amine with an aziridine or azetidine.

2. The sorbent of claim 1 , wherein the amine is an amine polymer.

3. 3. The sorbent of claim 2, wherein the amine polymer is branched, hyperbranched, dendritic, or linear.

4. 4. The sorbent of claim 3, wherein the amine polymer is one of polyethyleneimine, polypropyleneimine, polyallylamine, polyvinylamine, polyglycidylamine, or an amine-functionalized polystyrene-divinylbenzene polymer.

5. The CO ２ - Adsorbent according to claim 1, wherein the affinity phase is homogeneous.

6. The CO ２ - Adsorbent according to claim 1, wherein the affinity phase is heterogeneous.

7. 2. The sorbent of claim 1, wherein the percentage of the amines modified by reaction with aziridine or azetidine is about 0.001 to 1 of all primary and secondary amines in the amine polymer, a percentage of 1 meaning all of the primary and secondary amines.

8. 2. The sorbent of claim 1, wherein the percentage of the amines modified by reaction with aziridine or azetidine is about 0.01 to 0.5 of all primary and secondary amines in the amine polymer, with a percentage of 1 representing all of the primary and secondary amines.

9. The adsorbent of claim 2 , wherein the amine is physically impregnated into the pores of the support.

10. The adsorbent of claim 2 , wherein the amine is physically impregnated onto the surface of the support.

11. The adsorbent of claim 2 , wherein the amine is covalently bound to the surface of the support.

13. The CO ２ - the affinity phase comprises a structure selected from at least one of the following structures, where R ｘ is a substituent, Here, R １ , R ２ , R ３ , R ４ , R ５ , R ６ , and R ７ are each independently selected from a hydrogen atom, a hydroxide, a linear or branched alkyl, an alkanol, an alkoxy, an alkyl halide, a halide, an aldehyde, a ketone, a carboxylic acid, an ester, an amine, a sulfone, a phosphine, an aryl, an aryloxy, an aryl halide, benzyl, a phenol, or a heteroaryl; and R' are each independently selected from a hydrogen atom, an alkyl, an alkoxy, an alkyl halide, an aryl, benzyl, a phenyl, a phenol, an amine, a heteroaryl, or a nitroimidazole.

14. 10. The adsorbent of claim 1, wherein the support is a ceramic, a metal, a metal oxide, a plastic, cellulose, carbon, a zeolite, a metal organic framework (MOF), a porous organic framework (POF), a covalent organic framework (COF), a polymer of intrinsic microporosity (PIM), a polymer, fibrous cellulose, glass fiber, or boron nitride fiber.

15. A contactor comprising a structure and an adsorbent according to any one of claims 1 to 14.

16. 16. The contactor of claim 15, wherein the structure is selected from a honeycomb, a laminate sheet, a foam, a fiber, a minimum surface solid, a powder tray, a pellet, or a combination thereof.

17. CO from gas ２ Optionally, the gas is ambient air; The system comprises: CO ２ a first device configured to introduce the gas into the adsorbent or contactor of any one of claims 1 to 16 to bind the The CO ２ To release the bound CO ２ a second device configured to heat the adsorbent to at least a first temperature; The released CO ２ and a third device configured to collect the signal.

18. After heating, the adsorbent is regenerated to remove CO from the gas. ２ The system of claim 17, wherein the system is capable of adsorbing

19. 20. The system of claim 17, wherein the sorbent is in the form of a honeycomb, a laminated sheet, a foam, a fiber, a minimal surface solid, a powder tray, a pellet, or a combination thereof.

20. 20. The system of claim 19, wherein the honeycomb has an open face area of ​​about 0.3 to 0.

95.

21. 18. The system of claim 17, wherein the gas approaches the honeycomb at a velocity between 0.25 and 10 m / s.

22. The system converts CO from ambient air ２ wherein the ambient air is configured to operate to remove low concentrations of CO ２ 20. The system of claim 17, comprising:

23. CO from gas ２ Optionally, the gas is ambient air, The method comprises: CO ２ introducing said ambient air into the adsorbent of any one of claims 1 to 14 to bind to the adsorbent; The CO ２ heating the adsorbent to at least a first temperature to controllably release The CO ２ CO ２ collecting in a collection device.

24. Heating the adsorbent regenerates the adsorbent and removes CO from the ambient air. ２ The method of claim 23, wherein the

25. 24. The method of claim 23, wherein the adsorbent is heated by contact with steam.

26. The method comprises extracting CO from ambient air. ２ wherein the ambient air is configured to operate to remove low concentrations of CO ２ 24. The method of claim 23, comprising:

27. 24. The method of claim 23, wherein the sorbent is in the form of a honeycomb, a laminated sheet, a foam, a fiber, a minimal surface solid, a powder tray, a pellet, or a combination thereof.

28. A system for carrying out the method according to any one of claims 23 to 27.

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