Zinc halogenated-triazolate oxalate metal-organic framework sorbents, synthesis and use

Abstract

Zinc halogenated-triazolate oxalate metal-organic framework (MOF) sorbents constructed fully or partially with halogenated triazolate ligands, zinc, and a bidentate carboxylate are described herein along with their method of synthesis and its application for sorptive gas separation of carbon dioxide from a feed gas. The described zinc halogenated-triazolate oxalate MOF sorbents are suitable for applications where the feed gas has a reduced concentration of carbon dioxide and reduced levels of moisture. As compared to the prior art, the method of synthesis is environmentally friendly.

Description

[0001] ZINC HALOGENATED-TRIAZOLATE OXALATE METAL-ORGANIC FRAMEWORK SORBENTS, SYNTHESIS, AND USE

[0002] Field

[0003] The present invention relates to zinc containing halogenated-triazolate oxalate metal organic framework sorbents, its method of synthesis and use. More particularly, the present invention relates to a zinc containing 3-halogenated-1 ,2,4- triazolate oxalate metal organic framework sorbent, its method of synthesis and use for gas separation of CO2 from a multicomponent gas including, for example, the atmosphere, a flue gas, a process gas, and other gases containing CO2.

[0004] Background

[0005] Metal-organic frameworks (herein referred as “MOFs”) are a class of network solids composed of organic spacers linking metal ions or metal ion clusters. These materials are useful because of their high surface area and tunable pore structures. The long-range order of these materials allows them to be readily characterized by X-ray diffraction techniques, which facilitates in depth learning and understanding gas adsorption sites and mechanisms. The properties are of particular interest for rapid adsorption of gases. This class of material is can be employed for adsorbing and separating gases, for example, separation of carbon dioxide (hereinafter referred to as “CO2”) from a multicomponent gas including, for example, the atmosphere, a combustion or flue gas, a process gas, and other gases.

[0006] U.S. Patent 9,782,745, issued October 10, 2017, and titled “METAL ORGANIC FRAMEWORK, PRODUCTION AND USE THEREOF”, discloses certain Zn MOFs which exhibit high CO2 adsorption capacity with high selectivity for adsorption of CO2 compared to nitrogen and moreover exhibit good thermal and water stability. The MOF described therein could be subjected to a plurality of adsorption and desorption cycles with complete reversibility.

[0007] U.S. Patent 11 ,230,562, issued January 25, 2022, and titled “SYNTHESIS OF ZINC MOF MATERIALS”, teaches an improvement on the synthesis technique for preparing the Zn MOF disclosed in US Patent 9,782,745. Both U.S. Patent 9,782,745 and U.S. Patent 11 ,230,562 disclose a metalorganic framework (hereinafter referred to as “MOF”) having pores and wherein the framework includes zinc ions, oxalate, and a cycloazocarbyl compound. The cycloazocarbyl compound of the MOF therein is described as being at least bidentate, having 2, 3 or 4 nitrogen atoms, typically as part of a 5-membered ring. Examples of cycloazocarbyl compounds described therein include imidazolates, triazolates and tetrazolates, and more particularly 1 ,2,4-triazolate, 1 H-1 ,2,4-triazolate-1- carboxamidine, 3-amino-1 ,2,4-triazolate, imidazolate, 4-fluoroimidazolate, 2-methyl- imidazolate and 1 ,2,3,4-tetrazolate. Of particular interest therein is a Zn (II) material designated CALF-20, with the chemical formula Zn2Tz20x (where, Tz=1 ,2,4-triazolate, and Ox=oxalate). CALF-20 is an example of a MOF with a non-halogenated triazolate ligand.

[0008] U.S. Patent 9,782,745 exemplifies the synthesis of a particular example within this family of Zn MOF identified as CALF-20 which is performed as a batch process, solvo-thermally in a sealed autoclave at a pressure above ambient pressure. In this procedure, Zn(ll) oxalate and a stoichiometric excess of 1 ,2,4-triazole with respect to both Zn and oxalate are added to water and methanol in a polytetrafluoroethylene (PTFE)-lined autoclave. The mixture is subsequently heated in the sealed autoclave to 180°C for 48 hours (i.e., at high pressure) and washed with water. The space-time yield for this process is relatively low, of the order of about 40 kg / m3 / h, resulting in a cost of synthesis that is a significant limiting factor for CALF-20 and related MOFs. The reaction can also be carried out in pure methanol or ethanol. Subsequently, it has been found that in some cases, CALF-20 prepared by the autoclave method contains zinc oxide as an impurity as assessed by PXRD (powder X- ray diffraction), that is fully removed by an annealing process comprising two steps of heating to 200°C for 24 hours for each step, with a cooling and washing step in between. This purification step, however, adds additional time and cost to the synthesis of CALF-20.

[0009] U.S. Patent 11 ,230,562 discloses an improvement on the synthesis technique for preparing CALF-20 at reduced temperature and pressure. This method relies on forming a compound of cycloazocarbyl and oxalate or oxalate mixed with an additional chelating ligand prior to adding a zinc salt into the reaction media. The disclosure also exemplifies the use of a solvent comprised of a small quantity of alcohol plus water in a mixture.

[0010] PCT International Publication WO 2022 / 175927, entitled “SYNTHESIS METHOD OF ZINC METAL ORGANIC FRAMEWORK MATERIALS”, teaches an improvement on the synthesis technique disclosed in US Patent 11 ,230,562 for preparing the Zn MOF disclosed in US Patent 9,782,745. This method uses water as a solvent while reducing the reaction time.

[0011] CALF-20 is a desirable sorbent for certain gas separation applications, for example, separation of an acid gas, such as CO2, from a multicomponent gas stream where the concentration of the target component is moderate or high, for example, greater than about 15 mole % (hereafter all gas percentages are listed as mole % which is approximately equivalent to volume %), as CALF-20 offers a desirable level of capture or sorption capacity and durability when exposed to water and / or oxygen at elevated temperatures.

[0012] In applications where the concentration of the target component is at reduced concentration or dilute, for example, less than about 15%, conventional sorbents, for example, amines and KAUST-7, can have a desirable sorption capacity. However, these sorbents typically are unstable when exposed to water and / or oxygen, resulting in an undesirably low durability over time for a wide range of industrial applications.

[0013] In certain gas separation applications and processes where the multicomponent gas has a dilute concentration of the target component, for example, less than about 50%, 20%, or 15% concentration, with reduced levels of moisture, for example, less than about 5% relative humidity (hereinafter referred to as “RH”), and where the sorbent is at least periodically exposed to steam, oxygen, contaminants (for example, SOx and NOx), and elevated temperatures (for example, 80°C to 120°C), during the gas separation process, conventional sorbents have a limited sorbent capacity and / or durability. Example applications include but are not limited to gas separation of CO2 from a flue or combustion gas stream produced by a combustor using a fossil fuel, such as a natural gas combined cycle (NGCC) application which can produce a flue gas stream with about 3-5% CO2 concentration or up to about 10% CO2 concentration with exhaust gas recirculation. Under certain gas separation conditions including those described above, there is a requirement for a sorbent with a desirable sorbent capacity and durability which overcomes the restrictions of the prior art. A method of synthesis of the sorbent is also required.

[0014] Summary

[0015] A halogenated-triazolate oxalate metal-organic framework (XTz-MOF) sorbent comprising zinc as a metal ion, a halogenated-triazolate ligand, and a bidentate carboxylate ligand.

[0016] In a broad aspect of the invention, a halogenated N-membered ring ligand oxalate metal-organic framework sorbent comprising zinc as a metal ion wherein the N- member ring ligand has three or more nitrogen atoms on the ring.

[0017] A method of preparing the halogenated-triazolate oxalate metal-organic framework (XTz-MOF) sorbent disclosed herein, the method comprising:

[0018] (a) adding a plurality of reactants and a solvent together optionally in random order, a zinc ligand salt, or a zinc compound and a ligand compound, to form a reactant mixture;

[0019] (b) agitating the reactant mixture at a raised temperature, and

[0020] (c) optionally, forming a slurry.

[0021] In another broad aspect of the invention, a sorptive process for separating a multi-component gas, said multi-component gas comprising at least a first component and a second component, the process comprises:

[0022] (a) providing a contactor comprising the sorbent disclosed herein;

[0023] (b) admitting the multi-component gas as a feed stream into the contactor, sorbing at least a portion of the first component on and / or in the sorbent, producing a first product stream depleted in the first component relative to the feed stream, and recovering the first product stream from the contactor, and desorbing at least a portion of the first component adsorbed by and / or onto the sorbent, producing a second product stream enriched in the first component relative to the feed stream, and recovering the second product stream from the contactor.

[0024] Brief Description of the Drawings

[0025] Figure 1a shows the structure of a Zinc halogenated-triazolate oxalate metal-organic framework sorbent SMOF-106 viewed along the a axis;

[0026] Figure 1 b shows the structure of a Zinc halogenated-triazolate oxalate metal-organic framework sorbent SMOF-106 viewed along the b axis;

[0027] Figure 2 is a process flow diagram of an embodiment of the present invention, illustrating a sorptive process for separating a first component from a multicomponent gas using a contactor with a sorbent disclosed herein, wherein the sorptive process employs a first regenerating step;

[0028] Figure 3 is a process flow diagram of an embodiment of the present invention, illustrating a sorptive process for separating a first component from a multicomponent gas using a contactor having a sorbent disclosed herein, wherein the sorptive process is similar to the sorptive process in Fig. 2, but employs an additional step, such as a second regenerating step; and

[0029] Figure 4 shows the X-ray diffraction (XRD) patterns for the zinc halogenated-triazolate oxalate metal-organic framework sorbents SMOF-106 and SMOF-1 , wherein Line 401 illustrates a SMOF-106 simulation of a single crystal XRD solved structure, Line 402 illustrates a SMOF-106 powder XRD pattern from a batch of SMOF-106, and Line 403 illustrates a SMOF-1 powder XRD pattern from a batch of SMOF-1.

[0030] Description

[0031] Definitions

[0032] CO2: carbon dioxide

[0033] MOF: metal-organic framework

[0034] SMOF: Svante metal-organic framework Triazolate: 1 ,2,4-triazolate XTz: halogenated-triazolate Halogenated-triazolate: where halogen is Cl, Br, F, CF3 or any combination thereof with 1 ,2,4-triazolate or other functionalized cycloazocarbyl with at least three nitrogens on the five-membered ring, for example, 1 ,2,4-triazole, 3-amino-1 ,2,4-triazole, alkyl-1 ,2,4-triazole, 1 H- 1 ,2,4-triazolate-1-carboxamidine, and other functionalized 1 ,2,4-triazole, 1 ,2,3,4-tetrazolate.

[0035] Ox: oxalate or oxalic acid

[0036] XTz-MOF: halogenated-triazolate oxalate metal-organic framework NOx: nitrogen oxides (e.g. NO, NO2) SOx: sulfur oxides (e.g. SO2, SO3) RH: relative humidity Zn: zinc kg / m3 / d: kilogram per cubic meter per day, or kilogram per cubic meter per day

[0037] %: Mol% (or volume%) unless otherwise stated

[0038] Water: deionized water, demineralized water, distilled water, or other suitable water.

[0039] DI: deionized

[0040] Embodiments of a halogenated-triazolate oxalate metal-organic framework (XTz-MOF) sorbents comprise zinc as a metal ion, a halogenated triazolate ligand, and in embodiments, a triazolate ligand, a bidentate carboxylate ligand. Methods of synthesis thereof and use are disclosed herein. The XTz-MOF sorbents can be used for but is not limited to gas separation of a target component, for example, an acid gas such as CO2, from a multi-component gas including, for example, the atmosphere, a flue gas, a process gas, and other gases containing an acid gas.

[0041] Haloqenated-triazolate oxalate metal organic framework (XTz-MOF) sorbent

[0042] In embodiments, a halogenated-triazolate oxalate metal-organic framework (XTz-MOF) sorbent comprises zinc as a metal ion, a halogenated-triazolate ligand, and in embodiments, a triazolate ligand, and a bidentate carboxylate ligand. In further embodiments, the XTz-MOF sorbent can comprise zinc as a metal ion, a halogenated-triazolate ligand, a triazolate ligand, and a bidentate carboxylate ligand, where the halogen of the halogenated-triazolate ligand is Cl, Br, F, CF3, or any combination thereof. In yet further embodiments, the XTz-MOF sorbent can comprise zinc as a metal ion, a five-member ring N-ligand, an optional triazolate ligand, and a bidentate carboxylate ligand, where the five-member ring N-ligand is 3-chloro-1 ,2,4- triazolate, 3-bromo-1 ,2,4-triazolate, 3-fluoro-1 ,2,4-triazolate, 3-trifluoromethyl-1 ,2,4- triazolate, 3-amino-5-chloro-1 ,2,4-triazolate oxalate, 3-chloro-5-methyl-1 ,2,4-triazolate oxalate, or any combinations thereof; the triazolate ligand is a 1 ,2,4- triazolate ligand; and the bidentate carboxylate ligand is an oxalate ligand or a combination of oxalate and one or more chelating ligand other than oxalate. In yet further embodiments, the XTz-MOF sorbent comprises a zinc 3-chloro-1 ,2,4-triazolate oxalate, a zinc 3-bromo- 1 ,2,4-triazolate oxalate, a zinc 3-fluoro-1 ,2,4-triazolate oxalate, a zinc 3-trifluoromethyl- 1 ,2,4-triazolate oxalate, a zinc 3-amino-5-chloro-1 ,2,4-triazolate oxalate, a zinc 3-chloro- 5-methyl-1 ,2,4-triazolate oxalate, or any combinations thereof with 1 ,2,4-triazolate or other substituted cycloazocarbyl (or other N-member ring ligand) with at least three nitrogens on the triazole or five-membered ring, for example, 3-amino-1 ,2,4-triazole, alkyl-1 ,2,4-triazole and other functionalized 1 ,2,4-triazole, 1 ,2,3,4-tetrazole.

[0043] In one aspect, the XTz-MOF sorbent can comprise a molar ratio of the halogen ligand to the triazolate ligand of about 0.1 % to 100% halogen and / or about 99.9% to 0% triazolate ligand. In another aspect, the XTz-MOF sorbent comprises a molar ratio of zinc to oxalate to xTZ ratio of about 2:1 :2, where the xTZ is in a range of about 0.1 % to 100%, or about 1 % to 100% of halogenated functionalized triazole mixed with triazole or functionalized triazole.

[0044] Other three or more nitrogen containing ligands of compounds with more than five positions can optionally be used in the place of triazolate such as: triazine, tetrazine, or triapine.

[0045] A halogenated-triazolate oxalate metal-organic framework (XTz-MOF) sorbent as disclosed herein offers the advantages of increasing the hydrophobicity and water stability relative to conventional sorbents. In applications and conditions where the multicomponent gas comprises a low relative humidity, for example, less than about 5% RH, and a concentration of a target component in the multicomponent gas is at a reduced or dilute concentration, for example, less than about 15% concentration, the XTz-MOF sorbent comprising zinc as a metal ion, a halogenated-triazolate ligand or a five-member ring N-ligand, a triazolate ligand, and a bidentate carboxylate ligand offers the advantages relative to conventional sorbents including a greater capture capacity for the target component such as CO2, while maintaining a desirable stability and durability when exposed to water, oxygen, hot air (for example, between about 80°C - 150°C), and contaminants, for example, NOx and SOx.

[0046] Fig. 1a shows the structure of a zinc halogenated-triazolate oxalate metalorganic framework sorbent SMOF-106 viewed along the “a axis”. In the structure, Zn and 3-chloro-1 ,2,4-triaozle formed layers which are further connected by oxalate layers to form 3D porous frameworks.

[0047] Fig. 1 b shows the structure of a zinc halogenated-triazolate oxalate metalorganic framework sorbent SMOF-106 viewed along the “b axis”.

[0048] Synthesis methods of halogenated-triazolate oxalate metal-organic framework sorbents The XTz-SMOFs are synthesized by partially or fully replacing 1 ,2,4- triazole in the MOF with a halogenated-substituted 1 ,2,4-triazolate ligand including, for example, chloro-, bromo-, fluoro-, trifluoromethyl-. In synthesis embodiments, synthesis methods of the halogenated- triazolate oxalate metal-organic framework (XTz-MOF) sorbent having zinc as a metal ion, a five-member ring N-ligand, a triazolate ligand, and a bidentate carboxylate ligand, as described above, the synthesis method comprising:

[0049] 1 . Preparing a reactant mixture by dosing or adding a plurality of reactants and a solvent together in solution, wherein the reactants comprise a (halogenated substituted) triazole / triazolate including, for example, a 3-chloro-1 ,2,4- triazole, a 3-bromo-1 ,2,4-triazole, a 3-fluoro-1 ,2,4-triazole, a 3-trifluoromethyl-1 ,2,4- triazole, or any combination thereof with another five-member ring N-ligand with at least three N on the ring, for example 1 ,2,4-triaozle or substituted 1 ,2,4-triazole; triazole, a salt format of an alkaline metal triazolate, or zinc triazolate; oxalic acid, salt format of an alkaline metal, or zinc oxalate; if the triazolate or oxalate does not contain zinc, a basic zinc carbonate salt, a zinc oxide, zinc acetate or other zinc salt would need to be added. In one aspect, the reactants comprise a molar ratio of the five-member ring N-ligand / the carboxylate ligand / zinc where the ratio is 2 / 1 / 2, or the five-member ligand has a molar ratio greater than 2. In another aspect adding the plurality of reactants further comprises adding a molar ratio of a nitrogen-containing ligand (N-ligand) / the carboxylate ligand / zinc at a ratio where the molar ratio of the N-ligand is in is in a N- ligand range of about 2 to 5, the molar ratio of the carboxylate ligand is in a carboxylate range of about 0.5 to 2.5 and the molar ratio of the zinc compound is in a zinc range of about 1 to 2.5. In an embodiment, the solvent can be substantially of water or is water, for example, deionized water, demineralized water, distilled water, or other suitable water. In alternative embodiments, the solvent can be organic or alcohol based, and, in embodiments, combined with water. Dosing or adding the plurality of reactants and the solvent can be performed in a random sequence, in a predetermined sequence, or other suitable sequence. Preparation of the reactant mixture can be performed at a temperature equal to or greater than room or ambient temperature, at a temperature greater than 50°C, and at a pressure of equal to or greater than about atmospheric pressure.

[0050] 2. Agitating the reactant mixture at a raised temperature, in embodiments, for a period in time, for example, equal to or greater than about 0.5 hours, equal to or greater than about 1 hour, equal to or greater than about 2 hours, or equal to or greater than about 3 hours, to affect the synthesis of XTz-MOFs, and subsequently termination of the agitation and / or reactions of the reactant mixture.

[0051] 3. Forming a slurry of the reactant mixture.

[0052] In aspects, the synthesis method further includes producing the XTz-MOF sorbent at a space-time-yield (STY) equal to or greater than about 500 kg / m3 / d.

[0053] In further embodiments, raising the temperature of the reactant mixture and agitating the reactant mixture can be performed substantially concurrently or sequentially, for example, the step of raising the temperature of the reactant mixture is followed by the step of agitating the reactant mixture, the step of agitating the reactant mixture is followed by the step of raising the temperature of the reactant mixture, or the step of agitating the reactant mixture occurs concurrently with the step of raising the temperature of the reactant mixture. The agitating of the reactant mixture can be performed at a raised temperature, such as, a temperature between about 20°C and a temperature at which the reactant mixture boils, for example, about 100°C, or preferably about 50°C and a temperature at which the reactant mixture boils, for example, at about 100°C. In one aspect, the steps of raising the temperature of the reactant mixture and / or agitating the reacting mixture can be performed for a period of longer than a few hours.

[0054] Embodiments of the synthesis method can involve performing the synthesis of the reactant mixture at solvothermal conditions or where the reactions of the reactant mixture occur in a solvent at a temperature greater than about the boiling temperature of the solvent in a sealed vessel. The pressure in the sealed vessel can be at a pressure equal to or greater than about atmospheric pressure.

[0055] In embodiments of the synthesis method, after the step of forming a slurry, the synthesis method can further comprises forming a supported sorbent or an unsupported sorbent from the slurry; or forming a powder by at least one of filtering and drying of the slurry, and forming a supported sorbent or an unsupported sorbent from the powder. The XTz-MOF sorbent can be incorporated into macroscopic sorption structures such as laminated sheets on woven or non-woven substrates and passages in a monolithic or other suitable structure, and which are capable of large scale capture of acid gases such as CO2 from flue gases, process gasses, or from the ambient atmosphere.

[0056] The synthesis methods of the XTz-MOF sorbent as described herein offers the advantages of an environmentally friendly synthesis process by using only water as a solvent thereby producing the sorbent without the use of organic or alcohol based solvents (and associated disadvantages of using hazardous and toxic solvents, for example, added complexity and associated costs from handling, processing and disposal); producing the sorbent at a high space-time-yield, and enabling the use of zinc oxide or other zinc salts as a reactant and a zinc source.

[0057] Methods of use of haloqenated-triazolate oxalate metal-organic framework (XTz-MOF) sorbents

[0058] The sorbents as disclosed herein and its resulting sorption properties can be used for the purpose of separating a first component, for example, an acid gas component such as carbon dioxide, from a multi-component gas stream, for example, the atmosphere, a flue gas, a process gas, and other gases containing an acid gas. A sorbent can be used for industrial or utility deleterious effluent reduction and to provide a concentrated stream of the first component, for example, CO2, that can be further utilized for sequestration or other industrial usage.

[0059] In embodiments, a gas separator and / or a contactor of the present invention can be used in a sorptive process for separating a first component, for example carbon dioxide from a multi-component gas stream. Embodiments of the gas separator and / or contractor can be provided where the contactor comprises a sorbent disclosed herein. In one aspect, the contactor can be a parallel passage contactor, a monolithic contactor with passages for gas flow into the sorbent or a packed-bed contactor.

[0060] In a process embodiment, a sorptive process for sorptive gas separation of a multi-component gas or stream comprising at least a first component, for example, carbon dioxide is provided. In one such embodiment, the sorptive process can separate at least a portion of the first component from the multi-component fluid gas or stream. Fig. 2 illustrates a process embodiment, with a sorptive process 10 for separation of a multi-component fluid gas or stream comprising at least a first component, for example, carbon dioxide, and at least one of a second component, for example, nitrogen, a third component, for example, water, and a fourth component, for example, oxygen. Sorptive process 10 comprises the steps of a providing step 12, a sorbing step 20 and a first regenerating step 30, where the sorbing step 20 and a first regenerating step 30 can be repeated sequentially until sorptive process 10 is terminated.

[0061] Providing step 12, comprises providing a gas separator and / or contactor where the contactor comprises a sorbent disclosed herein. In one aspect, the contactor is a parallel passage contactor or a packed-bed contactor.

[0062] Sorbing step 20, comprises admitting a multi-component gas or stream, containing at least a first component, for example, an acid gas component such as carbon dioxide, and a second component, as a feed stream into the gas separator and / or the contactor; flowing the feed stream through the contactor and contacting the feed stream with the sorbent; sorbing at least a portion of the first component of the feed stream in and / or onto the sorbent, separating the first component from the feed stream, and forming a first product stream at least partially depleted in 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 components that are not adsorbed and / or onto the sorbent, for example, the second component such as nitrogen, can substantially flow through the contactor and exit the contactor and gas separator as the first product stream. In embodiments, a concentration of the first component in the feed stream is equal to or less than about 50% concentration, equal to or less than about 20% concentration, equal to or less than about 15% concentration; equal to or less than about 10% concentration; equal to or less than about 8% concentration; or equal to or less than about 5% concentration; and a 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.

[0063] In applications and processes where the multi-component gas or feed stream has a low or dilute concentration of the first component, for example, equal to or less than about 15% concentration and a low relative humidity, for example, equal to or less than about 10% RH, a gas separator comprising and employing the sorbent offers the advantages of a high sorption or sorptive capacity for the target or first component, with a high stability and durability when exposed to water, oxygen, hot air (for example, below about 150°C), and flue gas contaminants.

[0064] First regenerating step 30, comprises desorbing at least a portion of the first component adsorbed by and / or onto the sorbent, by at least one of a temperature swing mechanism, a pressure swing mechanism, and a partial pressure swing mechanism; forming a second product stream at least partially enriched in the first component relative to the feed stream, and recovering the second product stream from the contactor and / or gas separator.

[0065] In embodiments, first regenerating step 30 can further comprise admitting a first regeneration stream (such as steam) into the gas separator and / or contactor for contacting the sorbent as the first regeneration stream flows through the contactor; desorbing the first component adsorbed by and / or onto the sorbent; forming a second product stream at least partially enriched in the first component relative to the feed stream; and recovering the second product stream from the contactor and / or gas separator. Heat from the first regenerating stream and / or at least a portion of the first regeneration stream (such as water from the steam) can be adsorbed by and / or onto the sorbent, assisting in desorbing the first component adsorbed by and / or onto the sorbent.

[0066] In Fig. 2, sorbing step 20 and a first regenerating step 30 can be repeated sequentially until sorptive process 10 is terminated.

[0067] In alternative embodiments, a pressure swing sorptive process can be employed where sorbing step 20 is performed at an elevated pressure above atmospheric pressure, for example, greater than about 3 bar absolute, greater than about 5 bar absolute, or greater than about 10 bar absolute, and first regenerating step 30 is performed by reducing the pressure to a pressure less than the elevated pressure during sorbing step 20.

[0068] Fig. 3 illustrates a process embodiment, with a sorptive process 11 for separation of a multi-component fluid gas or stream comprising at least a first component, for example, carbon dioxide, and a second component. Sorptive process 11 comprises the steps of providing step 12, sorbing step 20 and first regenerating step 30, as shown in Fig. 2. However, sorptive process 11 further comprises a second regenerating step 40, and sorbing step 20, first regenerating step 30 and second regenerating step 40 can be repeated sequentially until sorptive process 11 is terminated.

[0069] In embodiments, during a second regenerating step 40, the water component adsorbed by and / or onto the sorbent can be desorbed from the sorbent by admitting a second regeneration stream, such as a gas stream with a low partial pressure of water, or a relative humidity less than a relative humidity within the contactor. In embodiments, desorption of the water component adsorbed by and / or on the sorbent can be performed or assisted by applying a vacuum and reducing a pressure within the contactor to a pressure below a saturation pressure of the steam within the contactor. Components desorbed from the sorbent during the second regenerating step 40, can form a third product stream which can be recovered from the contactor.

[0070] In embodiments, additional subsequent steps (not shown in Figs. 2 and 3) can follow, for example, a cooling step where a temperature of the sorbent can be reduced prior to repeating the sorbing step 20. The cycle of sorbing step 20, first regenerating step 730, and optional second regenerating step 40 (and optional subsequent steps) can be repeated as desired.

[0071] Examples

[0072] Synthesis Example 1 : SMOF-1 100% Bromo-triazole (Br-Tz)

[0073] Preparation of the reactant mixture was performed in a 250 mL 3-neck- round-bottom flask equipped with over-head stirrer, thermocouple, condenser and heating mantle, and charged with oxalic acid dihydrate 6.377 g (0.05 mol), 3-Br-1 ,2,4- triazole 15.16 g (0.1 mol) and 90 g of deionized (herein referred as “DI”) water at atmospheric pressure and at room temperature or about 20°C. Mixing of the reactant mixture was conducted for 1 h at 150 rpm agitation, followed by adding 11 .25 g (0.1 mol) basic zinc carbonate in portions over a 7 minute period. The reactant mixture was heated to about 100°C and the temperature was maintained for greater than 12 hours. A reactant mixture slurry was recovered from the flask prior to separating the solids from the slurry by suction filtration. The solids were washed with DI water until the conductivity of solids or filtrate was less than 100 microsiemens / cm. Powder was then collected and was dried in a convection oven at 110°C overnight. The yield of the product was greater than 95%.

[0074] Synthesis Example 2: SMOF-7 50% Triazole (Tz), 50% Bromo-triazole (Br-Tz)

[0075] Preparation of the reactant mixture was performed in a 250 mL 3-neck- round-bottom flask equipped with an over-head stirrer, a thermocouple, a condenser and a heating mantle, and charged with oxalic acid dihydrate 6.377 g (0.05 mol), 1 ,2,4- triazole 3.5 g (0.05 mol), 3-Br-1 ,2,4-triazole 7.55 g (0.05 mol) and 90 g of DI water at atmospheric pressure and at room temperature or about 20°C. Mixing of the reactant mixture was conducted for 1 h at 150 rpm, followed by adding 11 .25 g (0.1 mol) of basic zinc carbonate in portions over a 7 minute period. The reactant mixture was heated to about 100°C and that temperature was maintained for about 72 hours. A reactant mixture slurry was recovered from the flask prior to separating the solids 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 microsiemens / cm. Powder was then collected and dried in a convection oven at 110°C overnight. The yield of the product was greater than 95%.

[0076] Synthesis Example 3: SMOF-106 100% Chloro-triazole (Cl-Tz)

[0077] Preparation of the reactant mixture was performed in a 250 mL 3-neck- round-bottom flask equipped with over-head stirrer, thermocouple, condenser and heating mantle, and charged with oxalic acid dihydrate 1.59 g (0.013 mol), 3-CI-1 ,2,4- triazole 2.60 g (0.025 mol) and 50 g DI water at atmospheric pressure and at room temperature or about 20°C. Mixing of the reactant mixture was conducted for 1 h at 150 rpm agitation, followed by adding 2.81 g (0.025 mol) of basic zinc carbonate in portions over a 7 minute period. The reactant mixture was heated to about 100°C and the temperature was maintained for greater than 5 hours. A reactant mixture slurry was recovered from the flask prior to separating the solids 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 microsiemens / cm. Powder was then collected and dried in a convection oven at 110°C overnight. The yield of the product was greater than 95%.

[0078] Synthesis Example 4: SMOF-265 50% Triazole (Tz), 50% Chloro-triazole (Cl-Tz)

[0079] Preparation of the reactant mixture was performed in a 100ml Teflon® reactor and charged with oxalic acid dihydrate 0.22 g (1 .75 mmol), 3-CI-1 ,2,4-triazole 0.36 g (3.5 mmol) 1 ,2,4-triazole 0.24 g (3.5 mmol) and 50 g DI water. Mixing of the reactant mixture was conducted for 30 minutes at 150 rpm agitation, followed by adding 0.77 g (3.5 mmol) of zinc acetate. The Teflon® reactor was sealed and placed in an oven at a temperature of 180°C for a period of 2 days. A reactant mixture slurry was recovered from the flask prior to separate the solids from the slurry by suction filtration. The solids were then washed with DI water until the conductivity of the solids or filtrate was less than 100 microsiemens / cm. Powder was then collected and dried in a convection oven at 110°C overnight. The yield of the reactant mixture was greater than 95%.

[0080] SMOF-1 , SMOF-7, SMOF-106, SMOF-265 and other SMOFs disclosed herein can be synthesized where the one or more steps of increasing the temperature (heating) and / or agitating of the reactant mixture and can be conducted at equal to or greater than about atmospheric pressure, for example, stirring the reactant mixture while heating and / or sealed in an autoclave reactor.

[0081] A comparison of the CO2 uptake or sorptive capacity at various feed gas concentrations, 50°C and 0 % RH, for the CALF-20 sorbent and the XTz-MOF sorbents are shown in Table 1 below.

[0082] TABLE 1 - XTz-MOF and CALF-20 CO2uptakes (cc / g) at 50°C & 0% RH

[0083] Comparing the CALF-20 sorbent to the four XTz-MOFs, the XTz-MOFs showed higher CO2 uptakes or sorptive capacities at lower concentrations of CO2 (4% CO2 concentration) in the feed gas. SMOF-106 achieved about an 85% improvement in CO2 uptake relative to CALF-20 at 4% CO2 concentration, demonstrating its advantage in applications with low concentrations of the target gas, such as an acid gas or CO2. Such applications include, but are not limited to, NGCC applications. Additional advantages of the XTz-MOF’s include a higher selectivity for carbon dioxide relative to nitrogen, high water stability, high oxygen stability, and fast kinetics.

[0084] Fig. 4 shows the X-ray diffraction (XRD) patterns for the SMOF-106 and SMOF-1. Line 401 shows a SMOF-106 (100% Chloro-triazole) simulation of a single crystal XRD solved structure. Line 402 shows a SMOF-106 (100% chloro-triazole) powder XRD pattern from a batch of SMOF-106. Line 403 shows a SMOF-1 powder XRD pattern from a batch of SMOF-1 (100% Bromo-triazole).

Claims

WHAT IS CLAIMED IS:1 . A halogenated-triazolate oxalate metal-organic framework (XTz- MOF) sorbent comprising zinc as a metal ion, a halogenated-triazolate ligand, and a bidentate carboxylate ligand.

2. The XTz-MOF sorbent of claim 1 , further comprising a nonhalogenated triazolate ligand.

3. The XTz-MOF sorbent of claim 1 or 2, wherein the halogen of the halogenated-triazolate ligand is Cl, Br, F, CF3, or any combination thereof.

4. The XTz-MOF sorbent of any one of any one of claims 1 to 3, wherein the halogenated-triazolate ligand is 3-chloro-1 ,2,4-triazolate, 3-bromo-1 ,2,4- triazolate, 3-fluoro-1 ,2,4-triazolate, 3-trifluoromethyl-1 ,2,4-triazolate, 3-amino-5-chloro- 1 ,2,4-triazolate oxalate, 3-chloro-5-methyl-1 ,2,4-triazolate oxalate, or any combinations thereof; the triazolate ligand is a 1 ,2,4- triazolate 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 sorbent of claim 4, comprises zinc 3-chloro-1 ,2,4- triazolate oxalate, a zinc 3-bromo-1 ,2,4-triazolate oxalate, a zinc 3-fluoro-1 ,2,4-triazolate oxalate, a zinc 3-trifluoromethyl-1 ,2,4-triazolate oxalate, a zinc 3-amino-5-chloro-1 ,2,4- triazolate oxalate, a zinc 3-chloro-5-methyl-1 ,2,4-triazolate oxalate, or any combinations thereof.

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

7. A halogenated N-membered ring ligand oxalate metal-organic framework sorbent comprising zinc as a metal ion wherein the N-member ring ligand has three or more nitrogen atoms on the ring.

8. The sorbent of claim 7, wherein the N-member ring ligand is triazine, tetrazine, or triapine.

9. A method of preparing the sorbent of any one of claims 1 to 7, the method comprising:(a) adding a plurality of reactants and a solvent together optionally in random order, a zinc ligand salt, or a zinc compound and a ligand compound, to form a reactant mixture;(b) agitating the reactant mixture at a raised temperature, and(c) optionally, forming a slurry.

10. The method of claim 9, wherein the step of adding the plurality of reactants further comprises adding a molar ratio of a nitrogen-containing ligand (N- ligand) / the carboxylate ligand / zinc at a ratio where the molar ratio of the N-ligand is in a N-ligand range of 2 to 5, the molar ratio of the carboxylate ligand is in a carboxylate range of 0.5 to 2.5 and the molar ratio of the zinc compound is in a zinc range of 1 to 2.5.11 . The method of claim 9, wherein the solvent is water, an alcohol, or a mixture of water and an alcohol.

12. The method of claim 9, wherein the raised temperature is at a temperature equal to or greater than 50°C.

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

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

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

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

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

18. A sorptive process for separating a multi-component gas, said multi-component gas comprising at least a first component and a second component, the process comprising:(a) providing a contactor comprising the sorbent of any one of claims 1 to 17;(b) admitting the multi-component gas as a feed stream into the contactor, sorbing at least a portion of the first component on and / or in the sorbent, producing a first product stream depleted in the first component relative to the feed stream, and recovering the first product stream from the contactor, and(c) desorbing at least a portion of the first component adsorbed by and / or onto the sorbent, producing a second product stream enriched in the first component relative to the feed stream, and recovering the second product stream from the contactor.

19. The sorptive process of claim 18, wherein a concentration of the first component in the feed stream is equal to or less than 15% concentration.

20. The sorptive process of claims 18 or 19, wherein a relative humidity of the feed stream is equal to or less than 10% relative humidity.

Images