Modified metal-organic framework (MOF) compositions, process of making and process of use thereof

Abstract

This invention relates to modified MOF materials, methods of preparing them and processes using them. A modified MOF of the invention is modified by impregnating a MOF with an inorganic metal salt. The starting MOF contains at least one linker or ligand which contains an aryl amino group as part of its structure. These modified MOFs are able to adsorb either basic or acidic toxic industrial compounds (TIC). The modified MOFs can be used to remove TICs from various gaseous streams such as air.

Description

[Technical Field]

[0001] This invention relates to metal-organic framework (MOF) compositions having at least one linker molecule having an arylamine group. The MOFs have also undergone post-synthetic treatment with metal salt solutions. This invention further relates to methods for preparing and activating modified MOF compositions and methods for using MOF compositions to remove alkaline or acidic toxic industrial compounds (TICs) from a gas stream. [Previous Technology]

[0002] Adsorbent materials are well-known and have been found to have applications in many fields, such as air filtration and gas delivery. One specific use of adsorbents is to remove or eliminate contaminants from various gas streams, specifically toxic industrial compounds (TICs) present in the air stream. TICs can be classified as basic or base-forming compounds or acidic or acid-forming compounds. Typically, an adsorbent will exhibit an adsorption capacity for a variety of TICs. However, the capacity for each TIC depends on the properties of the adsorbent, which results in a material often performing well when adsorbing one TIC but poorly when adsorbing multiple TICs. For example, the MOF adsorbent Zr(NH2-BDC) has shown good adsorption capacity for NO2 but weaker capacity for ammonia. In many industries, filters that must eliminate multiple TICs are conventionally required. These technologies typically utilize multiple adsorbents. That is, the capacity for one TIC may be sufficient to eliminate the target in a particular gas stream, but not high enough to eliminate another TIC in the same gas stream. This necessitates the use of multiple adsorbents to eliminate two or more TICs from gas streams such as air. Therefore, the industry requires adsorbent materials capable of effectively removing or eliminating two or more TICs. This article describes a class of adsorbent materials capable of removing multiple TICs from gas streams at high capacity. More specifically, the industry needs MOFs capable of eliminating both basic and acidic TICs.

[0003] The applicant has developed a class of modified MOF materials that exhibit enhanced adsorption capacity for basic compounds (e.g., ammonia) while maintaining good adsorption capacity for acidic compounds (e.g., nitrogen dioxide or chlorine). The surprising aspect of this invention is that when a MOF is modified to have an enhanced adsorption capacity for basic compounds compared to an unmodified MOF, its adsorption capacity for acidic gases is not substantially reduced. The MOF material capable of adsorbing both acidic and basic gaseous compounds is prepared by: obtaining a synthetic MOF with good adsorption properties for acidic compounds and impregnating it with a metal salt solution, followed by activation.

[0004] US2019 / 0091503 discloses that MOFs (e.g., UiO-66) can be impregnated with metal compounds (e.g., metal hydroxides or metal hydrides) to disperse the metal compounds on the surface of the MOF or in its pores. This '503 publication states that such impregnated metal compounds have catalytic properties that can destroy chemical warfare agents (CWAs) such as sarin. The MOF disclosed in this '503 application differs from the MOF of this invention in that the MOF of this invention has the ability to adsorb both basic and acidic TICs. [Summary of the Invention]

[0005] One embodiment of the present invention is a modified metal-organic framework (MOF) composition comprising a MOF and a metal (M') inorganic salt impregnated on the MOF. The MOF comprises corner metal units containing metal ion atoms and linker molecules connecting the metal ion atoms. The metal (M) is selected from Zr, V, Al, Fe, Cr, Ti, Hf, Cu, Zn, Ni, In, Ce and mixtures thereof. The linker molecules are selected from at least one organic ligand containing an arylamine group or at least A combination of an organic ligand containing an arylamine group and at least one organic ligand without an arylamine group, wherein the (M') metal is selected from Li, Na, K, Mg, Mn, Ca, Sr, Ba, Sc, Y, Ti, Zr, Hf, V, Cr, Mo, W, Fe, Co, Ni, Cu, Ag, Zn, Cd, Al, Ga, In, Sn, Pb and mixtures thereof, the modified MOF composition being characterized by a minimum static ammonia capacity of 4 mmol / g measured at 10 Torr and 25 °C, and substantially retaining its capacity for acidic TIC.

[0006] Other embodiments are wherein the inorganic salt M' is selected from halides, sulfates, carbonates, nitrates, or mixtures thereof. Specific embodiments are wherein the salt is a halide salt.

[0007] In another embodiment, the M' metal system is present as a metal in an amount of about 0.25 wt.% to about 30 wt.%.

[0008] In another embodiment of the present invention, the M metal is selected from Zr, Al, Fe, Cu or Zn.

[0009] In yet another embodiment, at least one organic ligand containing an arylamine group is selected from 2-aminophenyl-1,4-dicarboxylic acid (NH2-BDC), 5-aminoisophthalic acid, 3-aminobenzoic acid, 4-aminobenzoic acid, and mixtures thereof.

[0010] In other embodiments, the at least one organic ligand that does not contain an aryl amine group is selected from terephthalic acid (BDC), isophthalic acid, benzoic acid, benzotriic acid, acrylic acid, and mixtures thereof.

[0011] In other embodiments, the metal M' is selected from Cu, Zn, Ni, Mn, Mg or Ca.

[0012] In specific embodiments, the MOF before modification disclosed herein is selected from Zr-UiO-66-NH2, Ce-UiO-66-NH2, Hf-UiO-66-NH2, Fe-MIL-101-NH2, Al-MIL-53-NH2, Cr-MIL-101-NH2, Zn-IROM-3, Cu-BTC-NH2, Ti-MIL-125-NH2, In-MIL-86-NH2 and mixtures thereof.

[0013] Another embodiment is a method for preparing a metal-organic framework (MOF) composition, comprising: a. forming a reaction mixture comprising a metal compound selected from Zr, V, Al, Fe, Cr, Ti, Hf, Cu, Zn, Ni, and Ce, and mixtures thereof; and a ligand selected from at least one organic ligand containing an amine group or a combination of at least one organic ligand containing an amine group and at least one organic ligand not containing an amine group; b. reacting the reaction mixture at a certain temperature for a period of time to form a MOF; c. separating the MOF to provide MOF powder; d. washing the MOF with an acid selected from formic acid, hydrochloric acid, nitric acid, sulfuric acid, and mixtures thereof, as appropriate, to provide a MOF having free amines; e. forming the MOF powder into a molded body, as appropriate; and f. impregnating the MOF molded body with an inorganic metal salt (M').

[0014] When using the step of forming MOF powder into a molded body, the impregnation step can occur before, during, or after the step of forming the molded body. When using the step of acid washing of MOF, acid washing is preferably performed before the impregnation step.

[0015] An embodiment of the present invention relates to a method for purifying a gas stream, comprising: contacting a gas stream containing at least one toxic industrial compound (TIC) with a modified metal-organic framework (MOF) composition under purification conditions, thereby removing at least a portion of the at least one TIC from the gas stream; wherein the modified MOF comprises a MOF and an inorganic metal (M') salt impregnated on the MOF, the MOF comprising corner metal units containing metal ion atoms and linker molecules connecting metal ion atoms of different corner metal units, wherein the metal (M) is selected from Zr, V, Al, Fe, Cr, Ti, Hf, Cu, Zn The modified MOF composition is characterized by having a minimum static ammonia capacity of at least 4 mmol / g, or at least 5 mmol / g, or at least 6 mmol / g, or at least 8 mmol / g, or at least 10 mmol / g, or at least 15 mmol / g, or at least 20 mmol / g, wherein the linker molecule is selected from at least one organic ligand containing an arylamine group or a combination of at least one organic ligand containing an arylamine group and at least one organic ligand not containing an arylamine group, wherein the metal (M') is selected from Li, Na, K, Mg, Ca, Sr, Ba, Mn, Sc, Y, Ti, Zr, Hf, V, Cr, Mo, W, Fe, Co, Ni, Cu, Ag, Zn, Cd, Al, Ga, In, Sn, Pb, or a mixture thereof, wherein the modified MOF composition is characterized by having a minimum static ammonia capacity of at least 4 mmol / g, or at least 5 mmol / g, or at least 6 mmol / g, or at least 8 mmol / g, or at least 10 mmol / g, or at least 15 mmol / g, or at least 20 mmol / g, as measured at 10 Torr and 25 °C. Typically, the static ammonia adsorption capacity is in the range of approximately 4 to approximately 25 mmol / g measured at 10 Torr and 25°C.

[0016] Other embodiments are wherein the gas flow is an air flow and at least one TIC is selected from ammonia, bromine, boron tribromide, bromine chloride, boron trichloride, bromine trifluoride, bromine pentafluoride, fluorinated carbon, chlorine, chlorine pentafluoride, chlorine trifluoride, chlorosulfonic acid, dichlorosilane, ethyl phosphorus dichloride, fluorine, formaldehyde, hydrogen bromide, hydrogen chloride, hydrogen cyanide, hydrogen fluoride, hydrogen iodide, nitric acid, nitrogen dioxide, dinitrogen tetroxide, dinitrogen trioxide, phosgene, phosphorus trichloride, silicon tetrafluoride, sulfuric acid, thiocyanate, titanium tetrachloride, tungsten hexafluoride, and mixtures thereof.

[0017] In a particular embodiment, the at least one TIC is an alkaline TIC, such as ammonia. In another embodiment, the at least one TIC is an acidic TIC, such as nitrogen dioxide or chlorine.

[0018] In another specific embodiment, the modified MOF is formed into a shape selected from agglomerates, granules, spheres, disks, monoliths, irregularly shaped particles, extrudates, and mixtures thereof. Adhesives may or may not be used in the manufacture of these shapes.

[0019] In another embodiment, the modified MOF is deposited on a solid carrier selected from the following: monolayer, spherical carrier, ceramic foam, glass fiber, fabric, non-fabric, film, granules, extruder, irregularly shaped particles and mixtures thereof.

[0020] A particular embodiment is a part of a solid carrier system made of fabric or non-fabric and / or a solid carrier or non-fabric system mask.

[0021] Another embodiment of the present invention comprises an apparatus comprising at least one impregnated MOF composition as disclosed herein. In one embodiment, the apparatus further comprises an adsorbent other than the impregnated MOF composition as disclosed herein. In one embodiment, the other adsorbent is an unimpregnated MOF composition. In one embodiment, the other adsorbent is zeolite. In one embodiment, the other adsorbent is activated carbon. In one embodiment, the apparatus comprises a mixture of at least one impregnated MOF composition as disclosed herein and another adsorbent. In one embodiment, the apparatus comprises an assembly containing a layer of at least one impregnated MOF composition as disclosed herein and at least one layer containing another adsorbent. In one embodiment, the apparatus comprises an assembly of at least two active layers comprising a first layer containing activated carbon and a second layer containing a modified MOF composition. In each of these devices, the modified metal-organic framework (MOF) composition is characterized by comprising a MOF and an inorganic metal (M') salt impregnated on the MOF, wherein the MOF comprises corner metal units containing metal ion atoms and linker molecules connecting the metal ion atoms of different corner metal units, wherein the metal (M) is selected from Zr, V, Al, Fe, Cr, Ti, Hf, Cu, Zn, Ni, In, Ce and mixtures thereof, and the linker molecule is selected from at least one organic compound containing an arylamine group. The ligand or a combination of at least one organic ligand containing an arylamine group and at least one organic ligand without an arylamine group, wherein the metal (M') is selected from Li, Na, K, Mg, Ca, Sr, Ba, Mn, Sc, Y, Ti, Zr, Hf, V, Cr, Mo, W, Fe, Co, Ni, Cu, Ag, Zn, Cd, Al, Ga, In, Sn, Pb and mixtures thereof, wherein the modified MOF composition is characterized by having a minimum static ammonia capacity of at least 4 mmol / g as measured at 10 Torr and 25°C, and substantially retaining its capacity for acidic TIC relative to the MOF composition before impregnation with the metal (M') salt.

[0022] After implementing the embodiments of the present invention, these and other aspects of the present invention will become clearer.

Implementation Method

[0023] Statement regarding federal government-sponsored research or development

[0024] This invention was developed with the support of the U.S. government under Agreement No. W911SR18C0031 granted by the U.S. Army Combat Capabilities Development Command Chemical Biological Center (CCDC CBC) and Agreement No. DE-SC0019959 granted by the U.S. Department of Energy. The government owns certain rights to this invention.

[0025] As used throughout the specification and the scope of the patent application, “substantial” means at least 70% or at least 80% or at least 90% or at least 95%.

[0026] As described above, the present invention relates to a modified metal-organic framework (MOF) composition, a method of using the composition, a method of manufacturing the composition, and an apparatus comprising the composition. The modified MOF comprises a MOF and a metal (M') salt impregnated on the MOF. Impregnation on the MOF means impregnation on the surface or in the pores of the MOF.

[0027] MOFs are coordination products of metal ions and at least bidentate organic ligands. MOFs are composed of corner metal units containing metal ion atoms and linker (i.e., ligand) molecules, which form a framework with high surface area and uniform or different predetermined pore sizes. Metals (M) that can be used to prepare the MOFs of this invention include (but are not limited to) Zr, V, Al, Fe, Cr, Ti, Hf, Cu, Zn, Ni, Hf, In, Ce, and combinations thereof. A preferred set or subset of the above metals includes (but is not limited to) Zr, Al, Fe, Cu, or Zn, and combinations thereof.

[0028] The organic ligand system reacting with metal ions is selected from at least one organic ligand containing an arylamine group or a combination of at least one organic ligand containing an arylamine group and at least one organic ligand without an amine group. Examples of organic ligands containing an arylamine group include (but are not limited to) 2-aminophenyl-1,4-dicarboxylic acid (NH2-BDC), 5-aminoisophthalic acid, 3-aminobenzoic acid, 4-aminobenzoic acid, and mixtures thereof. Examples of organic ligands without an arylamine group include (but are not limited to) terephthalic acid (BDC), isophthalic acid, benzoic acid, benzotris(II), acrylic acid, and mixtures thereof. When the ligand system comprises at least one organic ligand containing an arylamine group and at least one organic ligand without an amine group, the molar ratio of the amine-containing to the non-amine-containing ligand varies from 1:99 to 99:1, or 10:90 to 90:10, or 20:80 to 80:20, or 30:70 to 70:30, or 40:60 to 60:40, or 50:50. The addition of amine functional groups to MOFs by post-synthetic methods is also within the scope of this invention. Amine functional groups can be added post-synthetically at the organic ligand or by adding them at corner metal units. Typically, adding amines at organic linkers involves covalent reactions, while adding them at corner metal units involves the use of chelated species that bind to open metal sites or replace skeletal components that are not key structural features.

[0029] Specifically, the arylamine ligand can be added post-synthesized by suspending the MOF in a solvent to replace ligands without an arylamine group with ligands having an arylamine group. The solvent can be removed, and excess ligands are washed out with fresh solvent. Washing is repeated until all excess ligands are removed. Examples of organic ligands containing an arylamine group include (but are not limited to) 2-aminophenyl-1,4-dicarboxylic acid (NH2-BDC), 5-aminoisophthalic acid, 3-aminobenzoic acid, 4-aminobenzoic acid, and mixtures thereof. Postsynthetic ligand exchange can provide a combination of at least one organic ligand containing an arylamine group and at least one organic ligand without an amine group, wherein the molar ratio of the amine-containing to the non-amine-containing ligand varies from 1:99 to 99:1 or 10:90 to 90:10 or 20:80 to 80:20 or 30:70 to 70:30 or 40:60 to 60:40 or 50:50.

[0030] Another aspect of the composition of the present invention is an inorganic metal (M') salt, which is impregnated onto a MOF. The M' metal that can be used to prepare the composition of the present invention includes (but is not limited to) Li, Na, K, Mg, Ca, Sr, Ba, Mn, Sc, Y, Ti, Zr, Hf, V, Cr, Mo, W, Fe, Co, Ni, Cu, Ag, Zn, Cd, Al, Ga, In, Sn, Pb, and mixtures thereof. The M' metal exists in the form of a metal salt and is impregnated on the surface of the MOF or in the pores of the MOF. It should be noted that M and M' metals may be the same or different. Preferably, the M' metal is different from the M metal. The amount of metal salt impregnated on the MOF can vary considerably, but is typically about 1 wt% to about 70 wt.%, or about 5 wt.% to about 65 wt.%, or about 10 wt.% to about 60 wt.%, or about 15 wt.% to about 55 wt.%, or about 20 wt.% to about 50 wt.%, or about 25 wt.% to about 45 wt.%. The inorganic M' salt is selected from anhydrous or hydrated salts of halides, sulfates, carbonates, nitrates, or mixtures thereof. In one embodiment, the M' salt is an aqueous or anhydrous halide salt.

[0031] The metal-impregnated MOF of the present invention is characterized by the following properties. One property is a static ammonia capacity measured at 10 Torr and 25°C of at least 4 mmol / g, or at least 5 mmol / g, or at least 6 mmol / g, or at least 8 mmol / g, or at least 10 mmol / g, or at least 15 mmol / g, or at least 20 mmol / g. The metal-impregnated MOF is also characterized in that it substantially retains its capacity for acidic TICs relative to an unimpregnated MOF. Specifically, it retains about 80% of its adsorption capacity for at least one acidic TIC. A typical property of the MOF is a Brunauer-Emmett-Teller (BET) surface area of ​​at least 1,000, at least 1,100, at least 1,200, or at least 1,300, or at least 1,400 m² / g. The metal-impregnated MOF of the present invention is characterized in that it retains at least 50% of the BET surface area (SA) of the unimpregnated MOF.

[0032] Another aspect of the present invention is a method for preparing metal-impregnated MOFs. The first step of the synthesis involves preparing the MOF by synthesis known in the literature. Typically, a solution of the desired metal (M) and a ligand is prepared. The metal (M) is introduced in the form of a metal salt. The salt can be a nitrate, halide, sulfate, carbonate, oxyhalide, oxynitrate, oxysulfate, oxycarbonate, etc. Specific examples of salts that can be used include (but are not limited to) zirconium chloride, zirconium bromide, zirconium oxynitrate, zirconium oxychloride, vanadium chloride, copper sulfate, ferric chloride, zinc nitrate, or zinc carbonate and mixtures thereof.

[0033] As described above, the ligand to be used may be at least one organic ligand containing an arylamine group or a mixture of at least one organic ligand containing at least one arylamine group and an organic ligand without an arylamine group. Examples of organic ligands containing an amine group include (but are not limited to) 2-aminophenyl-1,4-dicarboxylic acid (NH2-BDC), 5-aminoisophthalic acid, 3-aminobenzoic acid, 4-aminobenzoic acid, and mixtures thereof. Examples of organic ligands without an amine group include (but are not limited to) terephthalic acid (BDC), isophthalic acid, benzoic acid, benzotris(II), acrylic acid, and mixtures thereof. If a mixture of ligands containing and without an amine group is used in the synthesis, it is added in molar ratio to achieve the desired molar ratio in the MOF as described above. The molar ratio of the metal salt to the ligand is also adjusted to achieve a specific molar ratio in the MOF.

[0034] The metal compound, which is a metal source M, and one or more ligands are mixed in a solvent or a mixture of solvents. Examples of solvents that may be used include (but are not limited to) amides, alcohols, water, and mixtures thereof. Specific solvents include dimethylformamide, water, ethanol, and isopropanol, and mixtures thereof.

[0035] Depending on the circumstances, an acid may be present in the reaction mixture during MOF synthesis. In one embodiment, the acid present during MOF synthesis comprises a monocarboxylic acid. In one embodiment, the monocarboxylic acid may be selected from formic acid, acetic acid, benzoic acid, dichloroacetic acid, trifluoroacetic acid, and mixtures thereof. In one embodiment, the acid present during MOF synthesis further comprises an inorganic acid, such as hydrochloric acid, nitric acid, or sulfuric acid, or mixtures thereof. In one embodiment, the acid present during MOF synthesis comprises a mixture of a monocarboxylic acid and an inorganic acid.

[0036] Once the reaction mixture is formed, i.e., all components are dissolved, the reaction mixture is reacted at a certain temperature for a period of time to form the desired MOF. The reaction temperature can vary from about 50°C to about 200°C or from about 75°C to about 125°C. The reaction mixture is reacted at the desired temperature for a time selected from about 1 hr. to about 78 hr. or about 8 hr. to about 48 hr. or about 12 hr. to about 24 hr. Once the MOF powder is formed, it is separated by means such as filtration, centrifugation, etc. In some embodiments, the separated MOF can be washed with an acid composition containing an inorganic acid. Depending on the circumstances, the acid washing solution can be a mixture of one or more inorganic acids and one or more organic acids. Preferred inorganic acids include hydrochloric acid, nitric acid, and sulfuric acid. Preferred organic acids include formic acid. The wet MOF is dried at a temperature of about 40°C to about 250°C or at a temperature of about 75°C to about 150°C. The drying time for wet MOF can vary substantially, but is typically about 2 hours to about 14 days, or about 8 hours to about 7 days, or about 2 days to about 7 days.

[0037] The MOF is then contacted with a metal salt solution of the metal M' source, thereby impregnating the MOF with the metal (M') salt. The M' metal may be selected from any or more of Li, Na, K, Mg, Ca, Sr, Ba, Mn, Sc, Y, Ti, Zr, Hf, V, Cr, Mo, W, Fe, Co, Ni, Cu, Ag, Zn, Cd, Al, Ga, In, Sn, Pb, and mixtures thereof. The salt may be an inorganic salt selected from one or more of metal nitrates, halides, sulfates, carbonates, etc., with halides being a specific example. The salt may be in hydrated or anhydrous form. Specific examples include (but are not limited to) magnesium chloride, nickel chloride, manganese chloride, zinc chloride, nickel nitrate, magnesium nitrate, nickel sulfate, and nickel carbonate. In one embodiment, the metal salt is NiCl2·6H2O. In one embodiment, the metal salt is MgCl2 (anhydrous). In one embodiment, the metal salt is MnCl2·4H2O. In one embodiment, the metal salt is anhydrous ZnCl2. In another embodiment, the metal salt is the hydrated form of ZnCl2. The metal salt is dissolved in a solution such as alcohol, water, acetone, or ether. The solution is contacted with the MOF at a temperature of about room temperature to about 65°C for about 1 minute to about 24 hours. The metal-impregnated MOF is then separated by filtration, centrifugation, etc., and then dried at a temperature of about 60°C to about 200°C.

[0038] Metal-impregnated MOFs can be formed into various shapes, as discussed below. In cases where a step of forming MOF powder into a molded body is used, the impregnation step can occur before, during, or after the steps of incorporating the binder and forming the molded body.

[0039] In one embodiment, a particular method involves preparing impregnated MOF particles as described below. The dried MOF powder is mixed with a binder and the mixture is thoroughly mixed. The binder that can be used includes both organic and inorganic binders. Examples of inorganic binders include (but are not limited to) clays (e.g., kaolin, magnesia, sepiolite, and gibbsite), alumina, silicon dioxide, metal oxides, and mixtures thereof. Specific examples of organic binders include (but are not limited to) polymers (e.g., polyvinylpyrrolidone (PVP)), starch, gelatin, cellulose, cellulose derivatives, sucrose, polyethylene glycol, and mixtures thereof.

[0040] In one embodiment, the MOF and binder are first thoroughly mixed, and then a solution containing the desired metal (M') salt is mixed with the MOF / binder mixture. This impregnated MOF is mixed for approximately 1 minute to approximately 24 hours until particles of the desired size are obtained. It should be understood that a range of sizes is always obtained, and therefore particle sizing, i.e., sieving, is required to separate particles having the desired size or size range. The particle size range will depend on the specific application of the modified MOF and will depend on various parameters such as pressure drop, bulk density, etc. Desired average diameters are approximately 1190 micrometers (16 mesh) to approximately 841 micrometers (20 mesh), or approximately 841 micrometers (20 mesh) to approximately 400 micrometers (40 mesh), or approximately 595 micrometers (30 mesh) to approximately 297 micrometers (50 mesh). Average diameter refers to the average diameter assuming an approximately spherical shape. This does not mean that the particles are actually spherical, but rather that they will pass through a sieve of a predetermined diameter. Once particles of the desired size are obtained, they are dried in a vacuum at a temperature of about 50°C to about 250°C for the required time to reach a pressure of about 0.1 Torr to activate the modified MOF. Other methods of incorporating binders into the MOF composition and forming particles or other molded articles will be understood by those skilled in the art.

[0041] As described, the metal-impregnated MOF composition of the present invention is used to remove both alkaline and acidic contaminants (e.g., TIC) from gas streams. Gas streams requiring purification may include (but are not limited to) air streams, industrial gas streams, waste gas streams, or contaminant gas streams. The modified MOF of the present invention is particularly suitable for removing acidic and alkaline contaminants from air streams. Contaminants or toxic industrial chemicals that can be removed by the MOF of the present invention include (but are not limited to) ammonia, bromine, boron tribromide, bromine chloride, boron trichloride, bromine trifluoride, bromine pentafluoride, fluorinated carbon, chlorine, chlorine pentafluoride, chlorine trifluoride, chlorosulfonic acid, dichlorosilane, ethyl phosphorus dichloride, fluorine, formaldehyde, hydrogen bromide, hydrogen chloride, hydrogen cyanide, hydrogen fluoride, hydrogen iodide, nitric acid, nitrogen dioxide, dinitrogen tetroxide, dinitrogen trioxide, phosgene, phosphorus trichloride, silicon tetrafluoride, sulfuric acid, thiocyanate, titanium tetrachloride, tungsten hexafluoride, and mixtures thereof.

[0042] The modified MOF can remove at least 50% or at least 60%, or at least 70%, or at least 80%, or at least 90%, or at least 95%, or at least 99% of the contaminants. In one embodiment, the gas flow is an air flow, the contaminants are NO2 and / or ammonia, and the modified MOF removes at least 80% of the NO2 or at least 80% of the ammonia in the air flow. In another embodiment, a container having an inlet and an outlet is filled with modified MOF material, and a gas flow passes through the modified MOF material, thereby substantially removing at least one alkaline contaminant and at least one acidic contaminant from the flow. To achieve the desired removal amount, the gas flow passes through the MOF at a flow rate of about 10 L / min to about 500 L / min, or about 30 L / min to about 200 L / min, or about 50 L / min to about 120 L / min.

[0043] Although the modified MOF composition of the present invention can be used in powder form, it is advantageous to form the MOF composition into various molded bodies, such as granules, spheres, discs, monoliths, irregularly shaped particles, and extrudates. Methods for forming these types of shapes are well known in the art. Specific methods for forming particulate materials are described above. The modified MOF material can be formed into various shapes by itself or by means of a binder. When selecting a binder, it is important to select one that ensures that the surface area and adsorption capacity are not adversely affected once the desired molded body is formed. Materials that can be used as binders include (but are not limited to) cellulose, silicon dioxide, carbon, alumina, and mixtures thereof. Forming the MOF composition into molded bodies can be carried out before, during, or after MOF impregnation.

[0044] The formation method typically involves preparing a thick paste material by mixing a modified MOF composition with a solvent or binder. Once the paste material is formed, it can be extruded through a die with an orifice of about 1-4 mm to form extrudates of different lengths (e.g., 2-50 mm). The paste or even the powder itself can be pressed under high pressure to form granules or pellets. Other methods of forming shapes include pressure molding, metal forming, granulation, pelletizing, extrusion, rolling, and pelletizing.

[0045] In another embodiment of the present invention, the metal-impregnated MOF material can be deposited on an object, such as, but not limited to, monoliths, spherical carriers, ceramic foams, glass fibers, fabrics, non-woven fabrics, films, granules, extrudates, irregularly shaped particles, and mixtures thereof. When the desired object is a monolith, spherical carrier, ceramic foam, granules, extrudate, or irregularly shaped particle, a slurry of the MOF composition is prepared and deposited on the object by means of immersion, spray drying, etc., followed by drying and calcination as appropriate. For films, the modified MOF composition can be formed directly on the film. The metal-impregnated MOF composition of the present invention can be deposited or dispersed on fabrics (woven and non-woven) or polymers by techniques such as electrospinning, direct crystal growth, and layer-by-layer deposition.

[0046] The metal-impregnated MOFs described in the preceding paragraphs can be used as is to purify air or other gas streams containing contaminants. Air or other gas streams can flow through the object (e.g., monolith, foam, film, fabric), whereby the metal-impregnated MOF adsorbs at least a portion of at least one contaminant. Metal-impregnated MOFs can also be placed in various types of rigid containers. For example, extrudates, pellets, or spheres can be contained in a bed through which air or other gas streams flow. This bed can be placed in various types of housings, such as filter canisters with inlets and outlets. Fabrics (both woven and non-woven) can also be formed as filters (e.g., but not limited to pleated filters), which can also be contained in rigid containers, such as a cylinder through which the stream to be treated flows. In one particular embodiment, the cylinder is part of a face mask. Pleated filters can also be supported in frames of various shapes and sizes through which gas streams flow. The frames can be made of various types of materials, such as, but not limited to, metal, wood, and plastic. Glass fibers can be formed into glass wool and housed in a rigid filter frame.

[0047] Metal-impregnated MOFs can be used in devices comprising at least one impregnated MOF composition as disclosed herein. In one embodiment, the device further comprises an adsorbent other than the impregnated MOF composition as disclosed herein. In one embodiment, another adsorbent is an unimpregnated MOF composition. In one embodiment, another adsorbent is zeolite. In one embodiment, another adsorbent is activated carbon. In one embodiment, the device comprises a mixture of at least one impregnated MOF composition as disclosed herein and another adsorbent. In one embodiment, the device comprises at least one layer of impregnated MOF composition as disclosed herein and at least one layer comprising another adsorbent. In one embodiment, the device comprises an assembly or device of a plurality of layers or non-layered mixtures containing particles, through which a gas flow (e.g., an air flow) flows. In a specific embodiment, the first layer in contact with the gas flow is a metal-impregnated MOF layer, and the second layer contains another adsorbent, such as activated carbon, zeolite, or other known adsorbents. In another embodiment, the gas stream may first contact a layer containing another adsorbent, and then contact a layer containing a modified MOF. Additional layers, such as a hopcalite layer, may be added as needed. For example, a layer of two different metal-impregnated MOFs or a layer of metal-impregnated MOF and unimpregnated MOF may be used. Alternatively, two or more modified MOFs may be mixed to form a layer, or the layer may comprise metal-impregnated MOF and unimpregnated MOF. These layers may be configured in a bed, which may be housed in a rigid structure, such as a tank or larger container (if a larger gas stream is to be purified, for example, airflow entering a commercial building). As mentioned above, the metal-impregnated MOF in the layer may be in powder form or any of the shapes and forms described above.

[0048] As described above, activated carbon, which can be used as another adsorbent, is a highly porous, high-surface-area adsorbent material with a predominantly amorphous structure. It is mainly composed of aromatic configurations of carbon atoms bonded by random cross-linking. The degree of order varies depending on the starting material and thermal history. Graphite flakes in steam-activated coal exhibit a certain degree of order, while more amorphous aromatic structures are found in chemically activated wood. Random bonding results in a highly porous structure with numerous cracks, fissures, and voids between the carbon layers. Activated carbon can be in the form of powder (PAC), granules (GAC), or extrusions (EAC). All three forms are available within a certain particle size range.

[0049] When modified MOF and activated carbon or other adsorbents are deposited on a fabric (woven or nonwoven), the fabric can be configured as a layer of a face mask.

[0050] Folded sheets can be formed that contain layers of activated carbon or another adsorbent and a metal-impregnated MOF. The folded sheets can be formed into various configurations (e.g., filter canisters) or housed in rigid containers, such as frames made of various materials (e.g., plastic, wood, metal, cardboard, etc.). Example 1: Synthesis of metal-impregnated Zr(NH2-BDC)

[0051] Zr(BDC-NH2) (also known as UiO-66-NH2) is prepared using a literature procedure. Typically, this procedure involves dissolving the NH2-BDC ligand in a solvent (e.g., DMF (dimethylformamide)), then adding formic acid, followed by heating the solution to approximately 90°C, adding ZrO(NO3), and reacting for a period of time to provide the MOF. The MOF powder is then separated, washed with DMF and acetone, washed with hydrochloric acid, and dried at approximately 100°C for about 12 hours.

[0052] Add 200 mg of the synthesized Zr(NH2-BDC) MOF to a 30 mL vial. Add 0.936 mmol of NiCl2·6H2O, MgCl2 (anhydrous), MnCl2·4H2O, or ZnCl2 (anhydrous) to this powder, followed by adding 10 mL of methanol for the NiCl2·6H2O and MgCl2 (anhydrous) samples or adding acetone for the ZnCl2 (anhydrous) samples. Sonicate the vial containing the mixture for 1 minute and then evaporate most of the methanol or acetone. Dry the resulting solid at 100°C overnight. Example 2: Synthesis of MgCl2-modified Zr(NH2-BDC) with binder

[0053] Zr(NH2-BDC) was prepared according to the procedure of Example 1, except that the MOF was dried at 80°C to achieve a hydration of 10-15% water. 1948 g of Zr(BDC-NH2) and 3 wt.% PVP were added to a disc mixer and the mixture was thoroughly mixed. A diluted MgCl2 solution mixture was prepared by diluting the MOF to approximately its pore volume using 328 mL of saturated MgCl2 solution. This was added to the mixture. The new mixture was continued to be mixed until particles were formed. The particles were sieved and the particles of the desired size were dried under vacuum at 100°C until a dynamic pressure (<0.1 Torr) was reached. Example 3: Zr(NH2-BDC) modified with ZnCl2 and containing a binder

[0054] Zr(NH2-BDC) was prepared according to the procedure of Example 1. The material was mixed with a colloidal silica solution in a disc mixer to obtain a compactable mixture. The material was rolled and ground to the desired size. The material was then immersed in a ZnCl2 / acetone solution at a selected concentration for about 20 hours to provide the desired zinc loading on the final MOF product. After immersion, the material was air-dried and then coated again using the same colloidal silica solution. This material was air-dried and then dried under vacuum at 100°C until the dynamic pressure (<0.1 Torr) was reached.

[0055] In the following examples, all ammonia adsorption and desorption measurements were performed at 25°C on a Micromeritics 3Flex surface characterization analyzer (Micromeritics, Norcross GA) by measuring to absolute pressure and using a 3-second equilibration time interval.

[0056] In the following examples, unless otherwise stated, all N2 gas adsorption and desorption measurements were performed on a Micromeritics Tristar II 3020 system (Micromeritics, Norcross, GA) at 77 K. Samples ranging from 75 to 200 mg were used in each measurement. The specific surface area of ​​N2 was calculated using the Bruno-Emmett-Teller (BET) model in the range of 0.005 < P / P0 < 0.05. N2 absorption was measured at P / P0 = 0.9, where P / P0 is the measurement pressure relative to atmospheric pressure.

[0057] Example 4: Absorption Test Table 1. Zr(NH2-BDC) Metal Impregnation and NH3 Absorption (mmol / g, at 25℃ and 10 Torr) Metal salts (preparations) M' load (wt.%) NH3 absorption In 77 o N2 absorption at K (cc / g) BET surface area (m²) 2 / g) none 0% 3.7 317 1290 NiCl2 (Example 1) 25% 12.2 151 464 NiCl2 (Example 1) 17% 8.7 286 692 MnCl2 (Example 1) 16% 8.5 153 503 MgCl2 (Example 2) 8% 7.9 218 697 MgCl2 (Example 1) 5% 7.3 158 626 MgCl2 (Example 1) 3% 7.2 281 1120 MgBr2 (Example 1) 6% 7.9 110 395 ZnCl2 (Example 3) 2% 5.5 203 768 ZnCl2 (Example 3) 4% 8.0 151 411

[0058] The above results show that Zr(NH2-BDC) MOFs can be impregnated with various metal salts to increase the adsorption capacity of metal-impregnated MOFs for ammonia. The results further indicate that increasing the amount of metal salt impregnated on the MOF increases the amount of ammonia adsorbed. However, as expected, the surface area decreases with increasing metal salt loading.

[0059] Cl2 absorption was measured as follows. Cl2 gas was injected into a mixing ballast and subsequently pressurized to obtain a concentration of 10,000 mg / m3. The ballast contents were then mixed with a diluent air stream under dry conditions to achieve a challenge concentration of 2,000 mg / m3. The mixed stream was then passed through an adsorbent bed immersed in a temperature-controlled water bath at 20°C. Approximately 50 mm3 of sample was packed into 4 mm id tubes, corresponding to a bed depth of 4 mm and a residence time of approximately 0.15 s. The effluent was then passed through a continuously operating Hewlett-Packard 5890 Series II gas chromatograph equipped with a photoionization detector with an 11.7 eV lamp. The loading was calculated by integrating the through curve at saturation. Table 2. Zr(NH2-BDC) metal impregnation and Cl2 absorption at 25°C and 10 Torr. Metal salts Load (wt.%) Cl2 absorption (mmol / g) none 0% 2.7 NiCl2 25% 3.1 MgCl2 5% 2.6

[0060] Table 2 shows that Zr(NH2-BDC) impregnated with nickel chloride or magnesium chloride retains the adsorption capacity of the unimpregnated MOF for chlorine (acidic TIC). This is an unexpected result, as MOFs impregnated with the same metal exhibit increased ammonia adsorption (see Table 1). The ability of MOFs to adsorb significant amounts of both basic and acidic TICs has not been previously observed. Example 5: Through-test

[0061] A fixed amount of Zr(NH2-BDC) (0.25 g) was packed into the permeation system. The first sample was not metal-impregnated, while the other samples underwent metal impregnation as described in Table 3. After nitrogen purging, a flow containing 250 ppm ammonia in He gas was introduced and flowed through the MOF at 50 standard cubic centimeters per second (sccms) at 25°C. The permeation time was recorded when the outlet concentration was measured to be 100 ppm. Table 3: Effect of metal impregnation on NH3 permeation of Zr(NH2-BDC) Metal salts Mg loading (wt.%) Duration (minutes) none 0% 295 MgCl2 5% 566 MgCl2 8% 571 MgCl2 12% 445

[0062] The results in Table 3 show that impregnation of Zr(NH2-BDC)MOF with a metal salt (MgCl2) increases the penetration time by up to 93%. Penetration depends on the concentration of the metal salt, with the maximum penetration observed at an 8 wt% magnesium loading.

[0063] Although specific embodiments have been mentioned above, it should be understood that the present invention is not limited thereto. Those skilled in the art will realize that various modifications can be made to the disclosed embodiments, and such modifications are intended to be within the scope of the present invention.

Claims

1. A method for purifying a gas stream, comprising: contacting the gas stream containing at least one toxic industrial compound (TIC) with a metal-impregnated metal-organic framework (MOF) composition under purification conditions, thereby removing at least a portion of at least one contaminant from the gas stream; wherein the metal-impregnated MOF comprises an MOF and an inorganic metal (M') salt impregnated on the MOF, the MOF comprising corner metal units containing metal ion atoms and linker molecules connecting metal ion atoms of different corner metal units, wherein the metal (M) is selected from Zr, V, Al, Fe, Cr, Ti, Hf, Cu, Zn, Ni, In, Ce and mixtures thereof. The linker molecules are selected from at least one organic ligand containing an arylamine group or a combination of at least one organic ligand containing an arylamine group and at least one organic ligand without an arylamine group, wherein the metal (M') is selected from Li, Na, K, Mg, Ca, Sr, Ba, Mn, Sc, Y, Ti, Zr, Hf, V, Cr, Mo, W, Fe, Co, Ni, Cu, Ag, Zn, Cd, Al, Ga, In, Sn, Pb and mixtures thereof. The metal-impregnated MOF composition is characterized by having a static ammonia capacity of at least 4 mmol / g as measured at 10 Torr and 25°C, and substantially retaining its capacity for acidic TIC relative to the unimpregnated MOF.

2. The method of claim 1, wherein the M' salt is selected from anhydrous or hydrated salts of halides, sulfates, carbonates, nitrates or mixtures thereof.

3. The method of claim 2, wherein the M' salt is an anhydrous or hydrated halide salt.

4. The method of claim 1, wherein the M' metal salt system is present as the metal in an amount of about 1 wt.% to about 70 wt.%.

5. The method of claim 1, further wherein the modified MOF retains at least 40% of its adsorption capacity for at least one acidic TIC compared to the adsorption capacity of its corresponding unmodified MOF.

6. The method of claim 1, wherein the gas stream is an air stream and the at least one TIC is selected from ammonia, bromine, boron tribromide, bromine chloride, boron trichloride, bromine trifluoride, bromine pentafluoride, fluorinated carbon, chlorine, chlorine pentafluoride, chlorine trifluoride, chlorosulfonic acid, dichlorosilane, ethyl phosphorus dichloride, fluorine, formaldehyde, hydrogen bromide, hydrogen chloride, hydrogen cyanide, hydrogen fluoride, hydrogen iodide, nitric acid, nitrogen dioxide, dinitrogen tetroxide, dinitrogen trioxide, phosgene, phosphorus trichloride, silicon tetrafluoride, sulfuric acid, thiocyanate, titanium tetrachloride, tungsten hexafluoride, and mixtures thereof.

7. The method of claim 6, wherein the at least one TIC-based ammonia.

8. The method of claim 6, wherein the at least one TIC is nitrogen dioxide.

9. The method of claim 1, wherein the organic ligand containing an arylamine group is selected from 2-aminophenyl-1,4-dicarboxylic acid (NH2-BDC), 5-aminoisophthalic acid, 3-aminobenzoic acid, 4-aminobenzoic acid, and mixtures thereof.

10. The method of claim 1, wherein the arylamine-free organic ligand is selected from terephthalic acid (BDC), isophthalic acid, benzoic acid, benzotriic acid, acrylic acid, and mixtures thereof.

11. The method of claim 1, wherein the M metal is selected from Zr, Al, Fe, Cu, Zn and mixtures thereof.

12. The method of claim 1, wherein the metal M' is selected from Cu, Zn, Ni, Mn, Mg, Ca and mixtures thereof.

13. The method of claim 1, wherein the MOF is selected from Zr-UiO-66-NH2, Ce-UiO-66-NH2, Hf-UiO-66-NH2, Fe-MIL-101-NH2, Al-MIL-53-NH2, Cr-MIL-101-NH2, Zn-IROM-3, Cu-BTC-NH2, Ti-MIL-125-NH2, In-MIL-86-NH2 and mixtures thereof.

14. The method of claim 1, wherein the modified MOF is formed in a shape selected from agglomerates, granules, spheres, disks, monoliths, irregularly shaped particles, extrudates and mixtures thereof.

15. The method of claim 1, wherein the modified MOF is deposited on a solid support selected from: monoliths, spherical supports, ceramic foams, glass fibers, fabrics, non-fabricated materials, films, granules, extrudates, irregularly shaped particles, and mixtures thereof.

16. The method of claim 15, wherein the solid carrier system is woven or nonwoven.

17. The method of claim 16, wherein the non-woven fabric is part of the face mask.

18. A metal-impregnated metal-organic framework (MOF) composition comprising a MOF and an inorganic metal (M') salt impregnated on the MOF, wherein the MOF comprises corner metal units containing metal ion atoms and linker molecules connecting the corner metal ion atoms, wherein the metal (M) is selected from Zr, V, Al, Fe, Cr, Ti, Hf, Cu, Zn, Ni, Hf, In, Ce and mixtures thereof, and the linker molecules are selected from at least one organic complex containing an arylamine group. The modified MOF composition is characterized by having a static ammonia capacity of at least one arylamine group and a combination of at least one organic ligand without an arylamine group, wherein the metal (M') is selected from Li, Na, K, Mg, Ca, Sr, Ba, Mn, Sc, Y, Ti, Zr, Hf, V, Cr, Mo, W, Fe, Co, Ni, Cu, Ag, Zn, Cd, Al, Ga, In, Sn, Pb, and is characterized by having a static ammonia capacity of at least 4 mmol / g as measured at 10 Torr and 25 °C and substantially retaining its capacity for acidic TIC.

19. The metal-impregnated MOF composition of claim 18, wherein the M' salt is selected from anhydrous or hydrated halides, sulfates, carbonates, nitrates or mixtures thereof.

20. The metal-impregnated MOF composition of claim 19, wherein the M' salt is an anhydrous or hydrated halide salt.

21. The metal-impregnated MOF composition of claim 18, wherein the M' metal is present as the metal in an amount of about 1 wt.% to about 70 wt.%.

22. The metal-impregnated MOF composition of claim 18, further wherein the modified MOF retains at least 80% of its adsorption capacity for at least one acidic TIC compared to the adsorption capacity of its corresponding unmodified MOF.

23. An apparatus comprising the composition of claim 18.

24. The apparatus of claim 23, further comprising at least one adsorbent of a non-metal-impregnated MOF.

25. The apparatus of claim 24, wherein the at least one metal-impregnated MOF composition and the at least one non-metal-impregnated MOF adsorbent are in the form of a mixture.

26. The apparatus of claim 24, wherein the apparatus comprises an assembly comprising a layer containing the at least one impregnated MOF composition and at least one layer containing the at least one non-metal-impregnated MOF adsorbent.

27. The device as claimed in claim 26, wherein the assembly is in the shape of a bed.

28. The apparatus of claim 27, wherein the bed is constrained by a rigid structure.

29. The apparatus of claim 26, wherein the assembly is part of a filter tank.

30. The apparatus of claim 24, wherein the adsorbent of the non-metal-impregnated MOF and the metal-impregnated MOF are deposited on a non-woven fabric.

31. The device as claimed in claim 26, wherein the assembly is part of a face mask.

32. The apparatus of claim 26, wherein the assembly is formed into a pleated filter material.

33. A method for preparing a metal-impregnated metal-organic framework (MOF), comprising providing an MOF comprising corner atoms of a metal ion and linker molecules connecting the corner atoms of the metal ion, wherein the metal (M) is selected from Zr, V, Al, Fe, Cr, Ti, Hf, Cu, Zn, Ni, Hf, In, Ce and mixtures thereof, and the linker molecules are selected from at least one organic ligand containing an arylamine group or a combination of at least one organic ligand containing an arylamine group and at least one organic ligand not containing an arylamine group; and making... The MOF is contacted with a solution of an inorganic metal (M') salt, wherein the metal (M') is selected from Li, Na, K, Mg, Ca, Sr, Ba, Mn, Sc, Y, Ti, Zr, Hf, V, Cr, Mo, W, Fe, Co, Ni, Cu, Ag, Zn, Cd, Al, Ga, In, Sn, Pb and mixtures thereof; the inorganic metal (M') salt solution is mixed for a time sufficient to impregnate the MOF with the metal (M'); the impregnated MOF is separated from the solution; and the impregnated MOF is dried.

34. The method of claim 33, wherein the inorganic M' salt is selected from anhydrous or hydrated salts of nitrates, halides, sulfates, carbonates or mixtures thereof.

35. The method of claim 33, wherein M' is selected from Cu, Zn, Ni, Mn, Mg, Ca or mixtures thereof.

36. The method of claim 33, further comprising the step of mixing the MOF with an adhesive before, during or after impregnation with an inorganic metal (M') salt, wherein the adhesive is selected from organic adhesives, inorganic adhesives or mixtures thereof.

37. The method of claim 36, wherein the adhesive is an organic adhesive selected from polymers, gelatin, starch, cellulose, cellulose derivatives, sucrose, polyethylene glycol and mixtures thereof.

38. The method of claim 36, wherein the adhesive is an inorganic adhesive selected from clay, alumina, silicon dioxide, metal oxides and mixtures thereof.

39. The method of claim 36, comprising the step of forming the MOF into particles, wherein the particles have an average diameter of about 50 micrometers to about 2 mm.

40. The method of claim 33, wherein the drying conditions include a temperature of about 25°C to about 250°C and a time of about 30 minutes to about 5 days.

41. The method of claim 33, which includes additional steps of washing the MOF with an acid-containing composition prior to the metal (M') impregnation step.