Halogenated-triazole oxalate zinc metal organic framework adsorbents, synthesis and uses

Abstract

Described herein are halogenated-triazole zinc oxalate metal organic framework (MOF) adsorbents that are composed entirely or partially of halogenated triazole salt ligands, zinc, and bidentate carboxylate salt ligands, and methods of their synthesis and their use for gas separation of carbon dioxide from a feed gas. The halogenated-triazole zinc oxalate MOF adsorbents described are suitable for use in applications where the feed gas has a reduced carbon dioxide concentration and a reduced moisture content. The synthesis method is environmentally friendly compared to the prior art.

Description

Technical Field

[0001] This invention relates to zinc-containing halo-triazole oxalate metal-organic framework adsorbents, their synthesis methods, and uses. More specifically, this invention relates to a zinc-containing 3-halo-1,2,4-triazole oxalate metal-organic framework adsorbent, its synthesis method, and its use for gas separation of CO2 from multi-component gases, including, for example, atmospheric gases, flue gas, process gases, and other gases containing CO2. Background Technology

[0002] Metal-organic frameworks (MOFs) are a class of network-like solids composed of organic spacers linking metal ions or clusters of metal ions. These materials are useful due to their high surface area and tunable pore structure. Their long-range order allows for easy characterization using X-ray diffraction, facilitating a deeper understanding of gas adsorption sites and mechanisms. These properties are particularly significant for the rapid adsorption of gases. These materials can be used for the adsorption and separation of gases, for example, the separation of carbon dioxide (hereinafter referred to as "CO2") from multi-component gases, including, for example, atmospheric gases, combustion gases or flue gases, process gases, and others.

[0003] U.S. Patent 9,782,745, granted on October 10, 2017, entitled "Metal-Organic Frameworks, Production Thereof, and Uses Thereof," discloses certain Zn MOFs that exhibit high CO2 adsorption capacity, high selectivity for CO2 adsorption compared to nitrogen, and good thermal and water stability. The MOFs described therein can withstand multiple adsorption and desorption cycles with complete reversibility.

[0004] U.S. Patent 11,230,562, issued on January 25, 2022, entitled “Synthesis of Zinc MOF Materials,” teaches improvements to the synthesis techniques for preparing the Zn MOF disclosed in U.S. Patent 9,782,745.

[0005] Both U.S. Patents 9,782,745 and 11,230,562 disclose a metal-organic framework (hereinafter referred to as "MOF") having pores, wherein the framework comprises zinc ions, oxalates, and cycloazocarbonyl compounds. The cycloazocarbonyl compounds of the MOF are described as being at least bidentate, having 2, 3, or 4 nitrogen atoms, which are typically part of a 5-membered ring. Examples of the cycloazocarbonyl compounds described include imidazole salts, triazole salts, and tetraazole salts, and more particularly include 1,2,4-triazole salts, 1H-1,2,4-triazol-1-formamidinium salt, 3-amino-1,2,4-triazole salts, imidazole salts, 4-fluoroimidazolium salts, 2-methylimidazolium salts, and 1,2,3,4-tetraazole salts. Of particular interest is the Zn(II) material designated CALF-20, with the chemical formula Zn₂Tz₂Ox (where Tz = 1,2,4-triazole salt and Ox = oxalate). CALF-20 is an example of a MOF with non-halogenated triazole salt ligands.

[0006] U.S. Patent 9,782,745 illustrates the synthesis of a specific example (identified as CALF-20) of this Zn MOF family, carried out as a batch process in a closed autoclave at pressures above ambient. In this procedure, zinc oxalate(II) and 1,2,4-triazole, in stoichiometric excess of both zinc and oxalate, are added to water and methanol in a PTFE-lined autoclave. The mixture is then heated to 180°C for 48 hours in the closed autoclave (i.e., under high pressure) and washed with water. The space-time yield of this method is relatively low, approximately 40 kg / m³. 3 The reaction rate is on the order of magnitude per hour, making synthesis cost a significant limiting factor for CALF-20 and related MOFs. The reaction can also be carried out in pure methanol or ethanol. It was subsequently found that, in some cases, CALF-20 prepared by the autoclave method contained zinc oxide as an impurity (as assessed by PXRD), which was completely removed by an annealing process consisting of two steps, each heated to 200°C for 24 hours, with intermediate cooling and washing steps. However, this purification step adds extra time and cost to the synthesis of CALF-20.

[0007] U.S. Patent 11,230,562 discloses an improvement in the synthetic technique for preparing CALF-20 at reduced temperatures and pressures. This method relies on forming a complex of a cycloazocarbonyl group and oxalate, or an oxalate mixed with other chelating ligands, before adding the zinc salt to the reaction medium. The disclosure also exemplifies the use of a solvent consisting of a small amount of alcohol and water in the mixture.

[0008] PCT International Publication WO 2022 / 175927, entitled "Method for Synthesizing Zinc Metal-Organic Framework Materials," teaches an improvement on the synthetic technique disclosed in U.S. Patent 11,230,562 for preparing Zn MOF disclosed in U.S. Patent 9,782,745. This method uses water as a solvent and simultaneously shortens the reaction time.

[0009] CALF-20 is an ideal adsorbent for certain gas separation applications, such as separating acidic gases (like CO2) from multi-component gas streams in which the concentration of the target component is moderate or high, for example, greater than about 15 mol% (all gas percentages are listed in mol% hereafter, which is approximately equivalent to volume%). This is because CALF-20 provides ideal trapping levels or adsorption capacity and durability when exposed to water and / or oxygen at elevated temperatures.

[0010] In applications where the concentration of the target component is reduced or diluted, such as less than about 15%, conventional adsorbents (e.g., amines and KAUST-7) can have ideal adsorption capacity. However, these adsorbents are generally unstable when exposed to water and / or oxygen, resulting in undesirably low durability over time for a wide range of industrial applications.

[0011] In certain gas separation applications and processes, where multi-component gases have target component concentrations diluted, such as less than about 50%, 20%, or 15%, with reduced humidity levels, such as less than about 5% relative humidity (hereinafter referred to as "RH"), and where the adsorbent is at least periodically exposed to vapors, oxygen, contaminants (e.g., SOx and NOx), and elevated temperatures (e.g., 80°C to 120°C) during the gas separation process, conventional adsorbents have limited adsorption capacity and / or durability. Example applications include, but are not limited to, the gas separation of CO2 from flue gas or combustion gas streams generated by fossil fuel burners, such as natural gas combined cycle (NGCC) applications, which can produce flue gas streams with a CO2 concentration of about 3% to 5% or, through exhaust gas recirculation, about 10% CO2 concentration. Under certain gas separation conditions including the above, there is a need for an adsorbent with ideal adsorption capacity and durability that overcomes the limitations of existing technologies. A method for synthesizing such an adsorbent is also needed. Summary of the Invention

[0012] A halo-triazole oxalate metal-organic framework (XTz-MOF) adsorbent comprising zinc as a metal ion, a halo-triazole salt ligand, and a bidentate carboxylate ligand.

[0013] In a broader aspect of the invention, there is a halo-N-membered ring ligand oxalate metal-organic framework adsorbent comprising zinc as a metal ion, wherein the N-membered ring ligand has three or more nitrogen atoms on the ring.

[0014] A method for preparing the halo-triazole oxalate metal-organic framework (XTz-MOF) adsorbent disclosed herein, the method comprising:

[0015] (a) Optionally, multiple reactants and solvents, zinc ligand salts, or zinc compounds and ligand compounds may be added together in a random order to form a reactant mixture; (b) Stirring the reactant mixture at an elevated temperature, and (c) Optionally, a slurry is formed.

[0016] In another broad aspect of this invention, an adsorption method for separating a multi-component gas (the multi-component gas comprising at least a first component and a second component) includes: (a) Providing a contactor containing the adsorbent disclosed herein; (b) Introducing a multi-component gas as a feed stream into the contactor, adsorbing at least a portion of the first component onto and / or into the adsorbent, generating a first product stream leaning towards the first component relative to the feed stream, and recovering the first product stream from the contactor, and At least a portion of the first component adsorbed by and / or adsorbed on the adsorbent is desorbed to produce a second product stream rich in the first component relative to the feed stream, and the second product stream is recovered from the contactor. Attached Figure Description

[0017] Figure 1a The structure of the halo-triazole zinc oxalate metal-organic framework adsorbent SMOF-106 as observed along the a-axis is shown. Figure 1b The structure of the halo-triazole zinc oxalate metal-organic framework adsorbent SMOF-106 as viewed along the b-axis is shown. Figure 2 This is a flowchart illustrating an embodiment of the present invention, which demonstrates an adsorption method for separating a first component from a multi-component gas using a contactor having the adsorbent disclosed herein, wherein the adsorption method employs a first regeneration step. Figure 3 This is a flowchart illustrating an embodiment of the present invention, which demonstrates an adsorption method for separating a first component from a multi-component gas using a contactor having the adsorbent disclosed herein, wherein the adsorption method is similar to... Figure 2 The adsorption method described earlier employs additional steps, such as a second regeneration step; and Figure 4X-ray diffraction (XRD) patterns of the halo-triazole zinc oxalate metal-organic framework adsorbents SMOF-106 and SMOF-1 are shown, where line 401 illustrates the simulation of the single-crystal XRD resolved structure of SMOF-106, line 402 illustrates the powder XRD pattern of SMOF-106 from a batch of SMOF-106, and line 403 illustrates the powder XRD pattern of SMOF-1 from a batch of SMOF-1. Detailed Implementation

[0018] definition CO2: Carbon dioxide MOF: Metal-Organic Framework SMOF: Svante Metal-Organic Framework Triazole salts: 1,2,4-triazole salts XTz: Halogenated Triazole Salt Halogenated triazole salts: wherein the halogen is Cl, Br, F, CF3 or any combination thereof, and is complexed with a 1,2,4-triazole salt or other functionalized cyclic azocarbonyl group containing at least three nitrogen atoms on a five-membered ring, such as 1,2,4-triazole, 3-amino-1,2,4-triazole, alkyl-1,2,4-triazole, 1H-1,2,4-triazole-1-formamidinium salt and other functionalized 1,2,4-triazole, 1,2,3,4-tetraazole salts.

[0019] Ox: Oxalate or oxalic acid XTz-MOF: Halogenated-triazole oxalate metal-organic framework NOx: Nitrogen oxides (e.g., NO, NO2) SOx: Sulfur oxides (e.g., SO2, SO3) RH: Relative Humidity Zn: Zinc kg / m 3 / d: kg / cubic meter / day %: mole% (or volume%), unless otherwise stated. Water: Deionized water, desalinated water, distilled water or other suitable water.

[0020] DI: Deionized Embodiments of halo-triazole oxalate metal-organic frameworks (XTz-MOF) adsorbents include zinc as a metal ion, a halotriazole salt ligand (and in this embodiment, a triazole salt ligand), and a bidentate carboxylate ligand. Their synthesis methods and uses are disclosed herein. XTz-MOF adsorbents can be used, but are not limited to, for the gas separation of target components (e.g., acidic gases, such as CO2) from multi-component gases (including, for example, atmospheric gases, flue gas, process gases, and other gases containing acidic gases).

[0021] Halogenated-triazole oxalate metal-organic framework (XTz-MOF) adsorbent In one embodiment, the halo-triazole oxalate metal-organic framework (XTz-MOF) adsorbent comprises zinc as a metal ion, a halo-triazole salt ligand (and in this embodiment, a triazole salt ligand), and a bidentate carboxylate ligand. In another embodiment, the XTz-MOF adsorbent may comprise zinc as a metal ion, a halo-triazole salt ligand, a triazole salt ligand, and a bidentate carboxylate ligand, wherein the halogen of the halo-triazole salt ligand is Cl, Br, F, CF3, or any combination thereof. In yet another embodiment, the XTz-MOF adsorbent may comprise zinc as a metal ion, a five-membered ring N-ligand, an optional triazole salt ligand, and a bidentate carboxylate ligand, wherein the five-membered ring N-ligand is 3-chloro-1,2,4-triazole salt, 3-bromo-1,2,4-triazole salt, 3-fluoro-1,2,4-triazole salt, 3-trifluoromethyl-1,2,4-triazole salt, 3-amino-5-chloro-1,2,4-triazole oxalate, 3-chloro-5-methyl-1,2,4-triazole oxalate, or any combination thereof; the triazole salt ligand is a 1,2,4-triazole salt ligand; and the bidentate carboxylate ligand is an oxalate ligand or a combination of oxalate and one or more chelating ligands other than oxalate. In yet another embodiment, the XTz-MOF adsorbent comprises zinc 3-chloro-1,2,4-triazole oxalate, zinc 3-bromo-1,2,4-triazole oxalate, zinc 3-fluoro-1,2,4-triazole oxalate, zinc 3-trifluoromethyl-1,2,4-triazole oxalate, zinc 3-amino-5-chloro-1,2,4-triazole oxalate, zinc 3-chloro-5-methyl-1,2,4-triazole oxalate, or any combination thereof with 1,2,4-triazole salts or other substituted cycloazocarbonyl groups (or other N-membered ring ligands) containing at least three nitrogen atoms on a triazole ring or a five-membered ring, such as 3-amino-1,2,4-triazole, alkyl-1,2,4-triazole, and other functionalized 1,2,4-triazoles, 1,2,3,4-tetraazoles.

[0022] In one aspect, the XTz-MOF adsorbent may comprise about 0.1% to 100% halogen and / or about 99.9% to 0% of a triazole salt ligand in a molar ratio of halogen to triazole salt ligand. In another aspect, the XTz-MOF adsorbent comprises a zinc to oxalate to xTZ molar ratio of about 2:1:2, wherein xTZ is a halogenated functionalized triazole mixed with triazole or functionalized triazole in the range of about 0.1% to 100% or about 1% to 100%.

[0023] Other compound ligands containing three or more nitrogen atoms and having more than five sites can be optionally used to replace triazole salts; such ligands include triazine, tetrazine, or triapine.

[0024] The halo-triazole oxalate metal-organic framework (XTz-MOF) adsorbents disclosed herein offer the advantage of increased hydrophobicity and water stability compared to conventional adsorbents. In applications and conditions where the multi-component gas includes low relative humidity, e.g., less than about 5% RH, and the concentration of the target component in the multi-component gas is reduced or diluted, e.g., less than about 15%, the XTz-MOF adsorbents, comprising zinc as a metal ion, halo-triazole salt ligands or five-membered ring N-ligands, triazole salt ligands, and bidentate carboxylate ligands, offer advantages over conventional adsorbents including greater capture capacity for target components such as CO2, while maintaining ideal stability and durability upon exposure to water, oxygen, hot air (e.g., about 80°C to 150°C), and pollutants such as NOx and SOx.

[0025] Figure 1a The structure of the halotriazole zinc oxalate metal-organic framework adsorbent SMOF-106, viewed along the "a-axis," is shown. In this structure, Zn and 3-chloro-1,2,4-triazole form layers, which are further connected by oxalate layers to form a 3D porous framework.

[0026] Figure 1b The structure of the halo-triazole zinc oxalate metal-organic framework adsorbent SMOF-106 as observed along the "b-axis" is shown.

[0027] Synthesis method of halo-triazole oxalate metal-organic framework adsorbents XTz-SMOF is synthesized by partially or completely replacing the 1,2,4-triazole in MOF with halogenated 1,2,4-triazole salt ligands (including, for example, chloro, bromo, fluoro, and trifluoromethyl ligands).

[0028] In the synthesis embodiment, the method for synthesizing a halo-triazole oxalate metal-organic framework (XTz-MOF) adsorbent having zinc, a five-membered ring N-ligand, a triazole salt ligand, and a bidentate carboxylate ligand as metal ions, as described above, includes: 1. A reactant mixture is prepared by quantitatively adding or co-doping multiple reactants and solvents in solution, wherein the reactants include (halogenated) triazoles / triazole salts, including, for example, 3-chloro-1,2,4-triazole, 3-bromo-1,2,4-triazole, 3-fluoro-1,2,4-triazole, 3-trifluoromethyl-1,2,4-triazole, or any combination thereof with another five-membered ring N-ligand containing at least three N atoms on the ring (e.g., 1,2,4-triazole or substituted 1,2,4-triazole); triazoles, salts of alkali metal triazoles, or zinc triazoles; oxalic acid, salts of alkali metals, or zinc oxalate; if the triazole salt or oxalate does not contain zinc, a basic zinc carbonate, zinc oxide, zinc acetate, or other zinc salt is required. In one aspect, the reactants comprise a molar ratio of a five-membered ring N-ligand / carboxylic acid ligand / zinc, wherein the ratio is 2 / 1 / 2, or the molar ratio of the five-membered ligand is greater than 2. In another embodiment, the addition of multiple reactants further includes adding nitrogen-containing ligands (N-ligands) / carboxylate ligands / zinc in a molar ratio of about 2 to 5 N-ligands, about 0.5 to 2.5 carboxylate ligands, and about 1 to 2.5 zinc compounds. In embodiments, the solvent may be substantially water or water, for example, deionized water, desalinated water, distilled water, or other suitable water. In alternative embodiments, the solvent may be organic or alcohol-based, and in embodiments, in combination with water. The quantitative dosing or addition of multiple reactants and solvents may be carried out in a random, predetermined, or other suitable order. The preparation of the reactant mixture may be carried out at a temperature equal to or above room temperature or ambient temperature, at a temperature greater than 50°C, and at a pressure equal to or above approximately atmospheric pressure.

[0029] 2. The reactant mixture is stirred at an elevated temperature for a period of time, in embodiments such as for about 0.5 hours, about 1 hour, about 2 hours, or about 3 hours, to influence the synthesis of XTz-MOF, and then the stirring and / or reaction of the reactant mixture is terminated.

[0030] 3. A slurry that forms a mixture of reactants.

[0031] In all aspects, the synthesis method further includes using a concentration equal to or greater than about 500 kg / m³. 3 XTz-MOF adsorbent is produced at a space-time yield (STY) of / d.

[0032] In another embodiment, raising the temperature of the reactant mixture and stirring the reactant mixture can be performed substantially simultaneously or sequentially. For example, the step of raising the temperature of the reactant mixture is followed by the step of stirring the reactant mixture, the step of stirring the reactant mixture is followed by the step of raising the temperature of the reactant mixture, or the step of stirring the reactant mixture occurs simultaneously with the step of raising the temperature of the reactant mixture. Stirring of the reactant mixture can be carried out at an elevated temperature, such as from about 20°C to the boiling point of the reactant mixture (e.g., about 100°C), or preferably from about 50°C to the boiling point of the reactant mixture (e.g., about 100°C). In one aspect, the steps of raising the temperature of the reactant mixture and / or stirring the reaction mixture can be carried out for a period of time exceeding several hours.

[0033] The synthesis method may involve synthesizing the reactant mixture under solvothermal conditions or in a solvent where the reaction of the reactant mixture is carried out in a closed container at a temperature above approximately the boiling point of the solvent. The pressure in the closed container may be equal to or higher than approximately atmospheric pressure.

[0034] In embodiments of the synthesis method, after the slurry formation step, the synthesis method may further include forming a supported or unsupported adsorbent from the slurry; or forming a powder by at least one of filtration and drying of the slurry, and forming a supported or unsupported adsorbent from the powder. XTz-MOF adsorbents can be incorporated into macroscopic adsorption structures, such as laminated sheets on woven or nonwoven substrates and channels in monolithic structures or other suitable structures, and these macroscopic adsorption structures are capable of large-scale capture of acidic gases such as CO2 from flue gas, process gas, or ambient atmosphere.

[0035] The synthesis method of the XTz-MOF adsorbent described herein offers the advantages of an environmentally friendly synthesis approach: producing the adsorbent using only water as a solvent without the use of organic or alcohol-based solvents (and avoiding the associated disadvantages of using hazardous and toxic solvents, such as the additional complexity and associated costs of handling, processing, and disposal); producing the adsorbent with a high space-time yield; and being able to use zinc oxide or other zinc salts as reactants and zinc sources.

[0036] Application methods of halogenated-triazole oxalate metal-organic framework (XTz-MOF) adsorbents The adsorbents disclosed herein and their resulting adsorption properties can be used to separate a first component (e.g., an acidic gas component, such as carbon dioxide) from a multi-component gas stream (e.g., atmosphere, flue gas, process gas, and other gases containing acidic gases). The adsorbents can be used for industrial or utility-grade hazardous effluent reduction and to provide a concentrated stream of the first component (e.g., CO2), which can then be further used for storage or other industrial applications.

[0037] In embodiments, the gas separator and / or contactor of the present invention can be used in an adsorption method for separating a first component (e.g., carbon dioxide) from a multi-component gas stream. Embodiments of the gas separator and / or contactor may be provided, wherein the contactor comprises the adsorbent disclosed herein. In one aspect, the contactor may be a parallel-channel contactor, an integral contactor having channels for gas flow into the adsorbent, or a packed-bed contactor.

[0038] In one embodiment of the method, an adsorption method is provided for separating an adsorbed gas from a multicomponent gas or stream containing at least a first component (e.g., carbon dioxide). In one such embodiment, the adsorption method can separate at least a portion of the first component from the multicomponent fluid gas or stream.

[0039] Figure 2 An embodiment of the method is illustrated, comprising an adsorption method 10 for separating a multi-component fluid gas or stream, the multi-component fluid gas or stream containing at least one of a first component (e.g., carbon dioxide) and a second component (e.g., nitrogen), a third component (e.g., water), and a fourth component (e.g., oxygen). The adsorption method 10 includes steps 12, 20, and 30, wherein the adsorption step 20 and the first regeneration step 30 may be repeated sequentially until the adsorption method 10 is terminated.

[0040] Step 12 includes providing a gas separator and / or a contactor, wherein the contactor contains the adsorbent disclosed herein. In one aspect, the contactor is a parallel-channel contactor or a packed-bed contactor.

[0041] The adsorption step 20 includes: introducing a multi-component gas or stream containing at least a first component (e.g., an acidic gas component, such as carbon dioxide) and a second component as a feed stream into a gas separator and / or contactor; allowing the feed stream to flow through the contactor and contacting the feed stream with the adsorbent; adsorbing at least a portion of the first component of the feed stream into and / or onto the adsorbent; separating the first component from the feed stream and forming a first product stream at least partially depleted of the first component relative to the feed stream; and recovering the first product stream from the contactor and / or gas separator. Although not specifically shown, the remaining component (e.g., the second component, such as nitrogen) that is not adsorbed into and / or onto the adsorbent may substantially flow through the contactor and exit the contactor and gas separator as the first product stream. In an embodiment, the concentration of the first component in the feed stream is equal to or less than about 50%, equal to or less than about 20%, equal to or less than about 15%, equal to or less than about 10%, equal to or less than about 8%, or equal to or less than about 5%; and the relative humidity of the feed stream is equal to or less than about 10% RH, equal to or less than about 8% RH, or equal to or less than about 5% RH.

[0042] In applications and methods involving multi-component gas or feed streams with low or diluted first component concentrations (e.g., equal to or less than about 15%) and low relative humidity (e.g., equal to or less than about 10% RH), gas separators incorporating and employing adsorbents offer advantages such as high adsorption or adsorption capacity for the target component or first component, as well as high stability and durability when exposed to water, oxygen, hot air (e.g., below about 150°C), and flue gas contaminants.

[0043] The first regeneration step 30 includes desorbing at least a portion of a first component adsorbed by and / or adsorbed on the adsorbent by at least one of a temperature-switching mechanism, a pressure-switching mechanism, and a partial pressure-switching mechanism; forming a second product stream that is at least partially enriched with the first component relative to the feed stream; and recovering the second product stream from a contactor and / or a gas separator.

[0044] In an embodiment, the first regeneration step 30 may further include introducing a first regeneration stream (such as steam) into a gas separator and / or contactor to contact the adsorbent as the first regeneration stream flows through the contactor; desorbing the first component adsorbed by and / or adsorbed on the adsorbent; forming a second product stream at least partially enriched with the first component relative to the feed stream; and recovering the second product stream from the contactor and / or gas separator. Heat from at least a portion of the first regeneration stream and / or the first regeneration stream (such as water from the steam) can be adsorbed by and / or adsorbed on the adsorbent, which facilitates the desorption of the first component adsorbed by and / or adsorbed on the adsorbent.

[0045] exist Figure 2 In this process, adsorption step 20 and first regeneration step 30 can be repeated sequentially until adsorption method 10 is terminated.

[0046] In an alternative embodiment, a pressure swing adsorption method may be used, wherein the adsorption step 20 is carried out at an elevated pressure above atmospheric pressure (e.g., greater than about 3 bar absolute pressure, greater than about 5 bar absolute pressure, or greater than about 10 bar absolute pressure), and the first regeneration step 30 is carried out by reducing the pressure to a pressure lower than the elevated pressure during the adsorption step 20.

[0047] Figure 3 An embodiment of the method is illustrated, wherein adsorption method 11 is used to separate a multicomponent fluid gas or stream comprising at least a first component (e.g., carbon dioxide) and a second component. Adsorption process 11 includes, as described above... Figure 2 The steps shown are step 12, adsorption step 20, and first regeneration step 30. However, the adsorption treatment 11 further includes a second regeneration step 40, and the adsorption step 20, the first regeneration step 30, and the second regeneration step 40 can be repeated sequentially until the adsorption treatment 11 is terminated.

[0048] In one embodiment, during the second regeneration step 40, water components adsorbed by and / or adsorbed onto the adsorbent can be desorbed from the adsorbent by introducing a second regeneration stream (such as a gas stream with low moisture pressure, or a stream with relative humidity lower than that within the contactor). In another embodiment, desorption of water components adsorbed by and / or adsorbed onto the adsorbent can be performed or assisted by applying a vacuum and reducing the pressure within the contactor to below the vapor saturation pressure within the contactor. The components desorbed from the adsorbent during the second regeneration step 40 can form a third product stream, which can be recovered from the contactor.

[0049] In the implementation, additional subsequent steps (not included) Figure 2 and Figure 3 (As shown in the diagram) A subsequent step, such as a cooling step, can be performed to lower the temperature of the adsorbent before repeating adsorption step 20. The cycle of adsorption step 20, first regeneration step 730, and optional second regeneration step 40 (and optional subsequent steps) can be repeated as needed.

[0050] Example Synthesis Example 1: SMOF-1 100% Bromotriazole (Br-Tz) The reaction mixture was prepared in a 250 mL three-necked round-bottom flask equipped with a top stirrer, thermocouple, condenser, and heating mantle. The flask was filled at atmospheric pressure and room temperature or about 20°C with 6.377 g (0.05 mol) of oxalate dihydrate, 15.16 g (0.1 mol) of 3-Br-1,2,4-triazole, and 90 g of deionized (hereinafter referred to as “DI”) water. The reaction mixture was stirred at 150 rpm for 1 h, followed by the addition of 11.25 g (0.1 mol) of basic zinc carbonate in 7-minute intervals. The reaction mixture was heated to approximately 100°C and maintained at this temperature for more than 12 hours. The reaction mixture slurry was recovered from the flask, and the solids were separated from the slurry by suction filtration. The solids were washed with DI water until the conductivity of the solids or filtrate was less than 100 μSiemens / cm. The powder was then collected and dried overnight in a convection oven at 110°C. The yield of the product was greater than 95%.

[0051] Synthesis Example 2: SMOF-7 50% triazole (Tz), 50% bromotriazole (Br-Tz) The reaction mixture was prepared in a 250 mL three-necked round-bottom flask equipped with a top stirrer, thermocouple, condenser, and heating mantle. The flask was filled at atmospheric pressure and room temperature or about 20°C with 6.377 g (0.05 mol) of oxalate dihydrate, 3.5 g (0.05 mol) of 1,2,4-triazole, 7.55 g (0.05 mol) of 3-bromo-1,2,4-triazole, and 90 g of DI water. The reaction mixture was mixed at 150 rpm for 1 h, followed by the addition of 11.25 g (0.1 mol) of basic zinc carbonate in 7-minute intervals. The reaction mixture was heated to about 100°C and maintained at this temperature for about 72 h. The reaction mixture slurry was recovered from the flask, and the solids were separated from the slurry by suction filtration. The solids were washed with DI water until the conductivity of the solids or filtrate was less than 100 μSiemens / cm. The powder was collected and dried overnight in a convection oven at 110°C. The yield of the product was greater than 95%.

[0052] Synthesis Example 3: SMOF-106 100% Chlorothalonazole (Cl-Tz) The reaction mixture was prepared in a 250 mL three-necked round-bottom flask equipped with a top stirrer, thermocouple, condenser, and heating mantle. 1.59 g (0.013 mol) of oxalic acid dihydrate, 2.6 g (0.025 mol) of 3-Cl-1,2,4-triazole, and 50 g of DI water were added at atmospheric pressure and room temperature or about 20°C. The reaction mixture was stirred at 150 rpm for 1 h, followed by the addition of 2.81 g (0.025 mol) of basic zinc carbonate in 7-minute intervals. The reaction mixture was heated to about 100°C and held at this temperature for more than 5 hours. The reaction mixture slurry was recovered from the flask, and the solids were separated from the slurry by suction filtration. The solids were washed with DI water until the conductivity of the solid or filtrate was less than 100 μSiemens / cm. The powder was collected and dried overnight in a convection oven at 110°C. The yield of the product is greater than 95%.

[0053] Synthesis Example 4: SMOF-265 50% triazole (Tz), 50% chlorotriazole (Cl-Tz) The reaction mixture was prepared in a 100 mL Teflon® reactor, which was charged with 0.22 g (1.75 mmol) oxalate dihydrate, 0.36 g (3.5 mmol) 3-Cl-1,2,4-triazole, 0.24 g (3.5 mmol) 1,2,4-triazole, and 50 g DI water. The reaction mixture was stirred at 150 rpm for 30 minutes, followed by the addition of 0.77 g (3.5 mmol) zinc acetate. The Teflon® reactor was sealed and placed in an oven at 180°C for 2 days. The slurry of the reaction mixture was recovered from the flask, and the solids were separated from the slurry by suction filtration. The solids were then washed with deionized water until the conductivity of the solid or filtrate was less than 100 μSiemens / cm. The powder was collected and dried overnight in a convection oven at 110°C. The yield of the reaction mixture was greater than 95%.

[0054] SMOF-1, SMOF-7, SMOF-106, SMOF-265 and other SMOFs disclosed herein can be synthesized by raising the temperature of the reactant mixture (heating) and / or stirring the reactant mixture in one or more steps, and can be carried out at a pressure equal to or above about atmospheric pressure, for example, by heating and / or stirring the reactant mixture in a closed autoclave reactor.

[0055] The comparison of CO2 absorption or adsorption capacity of CALF-20 adsorbent and XTz-MOF adsorbent at various feed gas concentrations, 50°C and 0% RH is shown in Table 1 below.

[0056] Table 1 – CO2 uptake (cc / g) of XTz-MOF and CALF-20 at 50°C and 0% RH

[0057] Comparing the CALF-20 adsorbent with four XTz-MOFs, the XTz-MOFs exhibited higher CO2 absorption or adsorption capacity at lower CO2 concentrations in the feed gas (4% CO2 concentration). SMOF-106 achieved approximately 85% improvement in CO2 absorption compared to CALF-20 at 4% CO2 concentration, demonstrating its advantage in applications with low concentrations of target gases such as acid gases or CO2. Such applications include, but are not limited to, NGCC applications. Additional advantages of XTz-MOFs include higher selectivity for carbon dioxide relative to nitrogen, high water stability, high oxygen stability, and rapid kinetics.

[0058] Figure 4 The X-ray diffraction (XRD) patterns of SMOF-106 and SMOF-1 are shown. Line 401 shows a simulation of the single-crystal XRD resolved structure of SMOF-106 (100% chlorotriazole). Line 402 shows the powder XRD pattern of SMOF-106 (100% chlorotriazole) from a batch of SMOF-106. Line 403 shows the powder XRD pattern of SMOF-1 (100% bromotriazole) from a batch of SMOF-1.

Claims

1. A halo-triazole oxalate metal-organic framework (XTz-MOF) adsorbent comprising zinc as a metal ion, a halo-triazole salt ligand, and a bidentate carboxylate ligand.

2. The XTz-MOF adsorbent according to claim 1 further comprises a non-halogenated triazole salt ligand.

3. The XTz-MOF adsorbent according to claim 1 or 2, wherein, The halogen of the halotriazole salt ligand is Cl, Br, F, CF3, or any combination thereof.

4. The XTz-MOF adsorbent according to any one of claims 1 to 3, wherein, The halogenated triazole salt ligand is 3-chloro-1,2,4-triazole salt, 3-bromo-1,2,4-triazole salt, 3-fluoro-1,2,4-triazole salt, 3-trifluoromethyl-1,2,4-triazole salt, 3-amino-5-chloro-1,2,4-triazole oxalate, 3-chloro-5-methyl-1,2,4-triazole oxalate, or any combination thereof; the triazole salt ligand is a 1,2,4-triazole salt ligand; and the bidentate carboxylate ligand is an oxalate ligand or a combination of oxalate and one or more chelating ligands other than oxalate.

5. The XTz-MOF adsorbent according to claim 4, comprising zinc 3-chloro-1,2,4-triazole oxalate, zinc 3-bromo-1,2,4-triazole oxalate, zinc 3-fluoro-1,2,4-triazole oxalate, zinc 3-trifluoromethyl-1,2,4-triazole oxalate, zinc 3-amino-5-chloro-1,2,4-triazole oxalate, zinc 3-chloro-5-methyl-1,2,4-triazole oxalate, or any combination thereof.

6. The XTz-MOF adsorbent according to any one of claims 1 to 5, further comprising a molar ratio of zinc to oxalate to XTz of about 2:1:2, wherein, The xTZ is a halogenated functionalized triazole mixed with triazole or functionalized triazole in the range of 0.1% to 100%.

7. A halo-N-membered ring ligand oxalate metal-organic framework adsorbent, comprising zinc as a metal ion, wherein, The N-membered cyclic ligand has three or more nitrogen atoms on the ring.

8. The adsorbent according to claim 7, wherein, The N-membered cyclic ligand is a triazine, a tetraazine, or triamcinolone.

9. A method for preparing an adsorbent according to any one of claims 1 to 7, the method comprising: (a) Optionally, multiple reactants and solvents, zinc ligand salts, or zinc compounds and ligand compounds may be added together in a random order to form a reactant mixture; (b) Stirring the reactant mixture at an elevated temperature, and (c) Optionally, a slurry is formed.

10. The method according to claim 9, wherein, The step of adding the various reactants further includes adding nitrogen-containing ligands (N-ligands) / carboxylate ligands / zinc in a certain molar ratio, wherein the molar ratio of the N-ligands is in the range of 2 to 5, the molar ratio of the carboxylate ligands is in the range of 0.5 to 2.5, and the molar ratio of the zinc compound is in the range of 1 to 2.

5.

11. The method according to claim 9, wherein, The solvent is water, alcohol, or a mixture of water and alcohol.

12. The method according to claim 9, wherein, The temperature increase is equal to or greater than 50°C.

13. The method according to any one of claims 9 to 12, further comprising converting the slurry into powder and converting the powder into a supported adsorbent or an unsupported adsorbent.

14. The method according to any one of claims 9 to 12, further comprising converting the slurry into a supported adsorbent or an unsupported adsorbent.

15. The method according to any one of claims 9 to 14, further comprising stirring the reactant mixture for a period of 0.5 hours to 12 hours.

16. The method according to any one of claims 9 to 15, further comprising adding the plurality of reactants and the solvent, and stirring the reactant mixture together at atmospheric pressure.

17. The method according to any one of claims 9 to 16, further comprising performing at least one of steps (b) and (c) under solvothermal conditions and optionally at a pressure equal to or greater than atmospheric pressure.

18. An adsorption method for separating a multi-component gas, wherein the multi-component gas comprises at least a first component and a second component, the method comprising: (a) Providing a contactor comprising an adsorbent according to any one of claims 1 to 17; (b) Introducing the multi-component gas as a feed stream into the contactor, adsorbing at least a portion of the first component onto and / or into the adsorbent, generating a first product stream depleted of the first component relative to the feed stream, and recovering the first product stream from the contactor, and (c) Desorb at least a portion of the first component adsorbed by and / or adsorbed onto the adsorbent to produce a second product stream rich in the first component relative to the feed stream, and recover the second product stream from the contactor.

19. The adsorption method according to claim 18, wherein, The concentration of the first component in the feed stream is equal to or less than 15%.

20. The adsorption method according to claim 18 or 19, wherein, The relative humidity of the feed stream is equal to or less than 10% relative humidity.

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