Methane concentration and oxidation system

Abstract

Disclosed herein are methods and systems for converting methane into CO2. In at least one embodiment, an exemplary method comprises: providing an initial gas stream comprising methane; concentrating the methane in the initial gas stream to produce a concentrated gas stream, wherein the methane concentration of the concentrated gas stream is at least 0.2 wt%; and feeding the concentrated gas stream to a reactor comprising a methane oxidation catalyst to effect conversion of the methane into CO2.

Description

METHANE CONCENTRATION AND OXIDATION SYSTEMCROSS-REFERENCE TO RELATED APPLICATIONS

[0001] This application claims the benefit of priority of U.S. Provisional Patent Application No. 63 / 542,618, filed October 5, 2023, the disclosure of which is hereby incorporated by reference herein in its entirety.FIELD OF THE DISCLOSURE

[0002] The present disclosure relates to methane catalysis, and in particular to systems for converting methane into carbon dioxide.BACKGROUND OF THE DISCLOSURE

[0003] While carbon dioxide is the greenhouse gas at the center of the global climate conversation, methane is arguably the bigger problem. Methane is more potent and much faster acting, yet, no technology exists that can address methane at most of its sources globally.

[0004] Atmospheric methane concentrations are rising and novel solutions are critical.Methane’s atmospheric concentration is roughly 0.4% that of carbon dioxide, yet has contributed fully 25% as much radiative forcing since preindustrial times. Atmospheric methane concentrations have increased almost twice as fast as CO2 over this time frame as well. The scientific community agrees that dramatic cuts in greenhouse emissions are needed by 2030, in order to avoid a 2 degree Celsius or greater temperature rise. Thus, there is a need for technological innovation to help curtail and contain global methane emission.SUMMARY OF THE DISCLOSURE

[0005] The following presents a simplified summary of various aspects of the present disclosure in order to provide a basic understanding of such aspects. This summary is not an extensive overview of the disclosure. It is intended to neither identify key or critical elements of the disclosure, nor delineate any scope of the particular embodiments of the disclosure or any scope of the claims. Its sole purpose is to present some concepts of the disclosure in a simplified form as a prelude to the more detailed description that is presented later.

[0006] One aspect of the present disclosure relates to a method of converting methane into CO2, the method comprising: providing an initial gas stream comprising methane; concentrating the initial gas stream to produce a concentrated gas stream, wherein the methane concentrationof the concentrated gas stream is at least 0.2 wt%; and feeding the concentrated gas stream to a reactor comprising a methane oxidation catalyst to effect conversion of the methane into CO2.

[0007] Another aspect of the present disclosure relates to a method of converting methane into CO2, the method comprising: receiving a concentrated gas stream or concentrating an initial gas stream to produce the concentrated gas stream, wherein the methane concentration of the concentrated gas stream is at least 0.2 wt%; and feeding the concentrated gas stream to a reactor comprising a methane oxidation catalyst to effect conversion of the methane into CO2.

[0008] In at least one embodiment, the method further comprises: maintaining an O2 concentration in the reactor from about 10 wt% to less than 21 wt%.

[0009] In at least one embodiment, the methane concentration of the concentrated gas stream is about 0.2 wt% to about 17 wt%.

[0010] In at least one embodiment, the methane concentration of the concentrated gas stream is about 0.25 wt% to about 5 wt%.

[0011] In at least one embodiment, the methane concentration of the concentrated gas stream is about 0.3 wt% to about 1.2 wt%.

[0012] In at least one embodiment, the methane concentration of the concentrated gas stream is at least 1.5, at least 5.0, at least 10.0 times greater than the methane concentration of the initial gas stream.

[0013] In at least one embodiment, the methane concentration of the initial gas stream is about 0.01 wt% to about 4.6 wt%.

[0014] In at least one embodiment, the methane concentration of the initial gas stream is about 0.1 wt% to about 3 wt%.

[0015] In at least one embodiment, the methane concentration of the initial gas stream is about 0.5 wt% to about 2 wt%.

[0016] In at least one embodiment, the conversion of methane is at least about 25%.

[0017] In at least one embodiment, the conversion of methane is at least about 50%.

[0018] In at least one embodiment, the conversion of methane is maintained below about 75%.

[0019] In at least one embodiment, the conversion of methane is maintained below about 85%.

[0020] In at least one embodiment, the reactor comprises two or more vessels with intercooling.

[0021] In at least one embodiment, heat removed from a reaction product of the reactor is used for generating steam.

[0022] In at least one embodiment, the oxidation reactor is in the form of a shell-and-tube heat exchanger with hot oil and / or thermal fluid and / or evaporating water as cooling fluid to provide for heat removal.

[0023] In at least one embodiment, the oxidation reactor has cooling tubes integrated into it to allow for heat removal.

[0024] In at least one embodiment, concentrating the methane in the initial gas stream comprises feeding the initial gas stream to an adsorption system.

[0025] In at least one embodiment, the adsorption system is a simulated moving bed adsorption system.

[0026] In at least one embodiment, the adsorption system is a temperature-swing adsorption system.

[0027] In at least one embodiment, the adsorption system is a pressure-swing adsorption system.

[0028] In at least one embodiment, the adsorption system comprises a clathrate hydrate adsorbent.

[0029] In at least one embodiment, the adsorption system comprises one or more solid adsorbents selected from zeolites, metal organic frameworks, carbon-based adsorbents, or a combination thereof.

[0030] In at least one embodiment, the adsorption system is adapted to cycle between an adsorption stage, a cooling stage, and a desorption stage. In at least one embodiment, the method further comprises: effecting desorption during the desorption stage by transmitting heat from a reaction product of the reactor to the adsorption system.

[0031] In at least one embodiment, concentrating the methane comprises concentrating the methane using a liquid absorbent.

[0032] In at least one embodiment, concentrating the methane comprises concentrating the methane using a membrane system.

[0033] In at least one embodiment, the methane oxidation catalyst comprises a copper zeolite catalyst.

[0034] In at least one embodiment, the methane oxidation catalyst comprises a zeolite catalyst with more than one transition metals used for exchange.

[0035] In at least one embodiment, the methane oxidation catalyst comprises a zeolite catalyst with one or more transition metals comprising nickel, iron, cobalt, copper, manganese, vanadium, cerium, zinc, tungsten, molybdenum, platinum, palladium, silver, gold, or a combination thereof.

[0036] In at least one embodiment, the methane oxidation catalyst comprises a zeolite catalyst mixed with a supported oxide catalyst. In at least one embodiment, the supported oxide catalyst comprises one or more of zirconia, titania, silica, alumina, or a combination thereof.

[0037] In at least one embodiment, the methane oxidation catalyst is a formed catalyst. In at least one embodiment, the formed catalyst is in the form of tablets, granules, extrudates, or a combination thereof.

[0038] In at least one embodiment, the methane oxidation catalyst is coated onto a substrate.

[0039] In at least one embodiment, the methane oxidation catalyst is a combination of coated substrates and formed catalysts.

[0040] A further aspect of the present disclosure relates to a system for converting methane into CO2, the system comprising: a methane concentration system adapted to concentrate methane within a methane-containing gas stream; and a reactor fluidly coupled to the methane concentration system, the reactor comprising a methane oxidation catalyst adapted to support a methane oxidation reaction.

[0041] In at least one embodiment, the methane concentration system comprises a plurality of adsorption columns configured for moving bed adsorption.

[0042] In at least one embodiment, at least one of the plurality of adsorption columns comprises one or more of a solid adsorbent, a liquid absorbent, or a clathrate hydrate adsorbent. In at least one embodiment, the system is configured to effect desorption of at least one of the adsorption columns during a desorption stage using heat from a methane oxidation reaction product of the reactor. In at least one embodiment, the system is configured to cool at least one of the adsorption columns during a cooling stage.

[0043] In at least one embodiment, the system is configured to feed a flow of an Ch- containing gas stream to the reactor to support the methane oxidation reaction.

[0044] In at least one embodiment, the methane oxidation catalyst comprises a copper zeolite catalyst.

[0045] In at least one embodiment, the methane oxidation catalyst comprises a zeolite catalyst with more than one transition metals used for exchange.

[0046] In at least one embodiment, the methane oxidation catalyst comprises a zeolite catalyst mixed with a supported oxide catalyst.

[0047] In at least one embodiment, the methane oxidation catalyst is a formed catalyst.

[0048] In at least one embodiment, the formed catalyst is in the form of tablets, granules, extrudates, or a combination thereof.

[0049] In at least one embodiment, the catalyst is added to a substrate.

[0050] In at least one embodiment, the catalyst is a combination of coated substrates and formed catalysts.

[0051] In at least one embodiment, the conversion of methane is at least about 25%.

[0052] In at least one embodiment, the conversion of methane is at least about 50%.

[0053] In at least one embodiment, the conversion of methane is maintained below about 75%.

[0054] In at least one embodiment, the conversion of methane is maintained below about 85%.

[0055] In at least one embodiment, a bed size of the reactor system is about 5-35% of a bed size of a similar system that is capable of achieving about 99% methane conversion.

[0056] In at least one embodiment, a bed size of the reactor system is from about 1 m3to less than about 10 m3, less than about 8 m3, less than about 6 m3, less than about 4 m3, or less than about 3 m3.

[0057] In at least one embodiment, the reactor comprises two or more vessels with intercooling.

[0058] In at least one embodiment, the system is adapted to generate steam using heat removed from a reaction product of the reactor.

[0059] A further aspect of the present disclosure relates to a system for converting methane into CO2, the system comprising: a methane adsorbent or absorbent adapted to concentrate methane within a methane-containing gas stream; and a methane oxidation catalyst adapted to support a methane oxidation reaction, wherein the methane adsorbent or absorbent and the methane oxide catalyst are contained together within a single vessel.

[0060] In at least one embodiment, the methane adsorbent or absorbent comprises one or more solid adsorbents comprising zeolites, metal organic frameworks, carbon-based adsorbents, or a combination thereof.

[0061] In at least one embodiment, the vessel comprise a membrane system to facilitate concentration and oxidation of methane within the vessel.

[0062] In at least one embodiment, the system is configured to feed a flow of an Ch- containing gas stream to the methane oxide catalyst to support the methane oxidation reaction.

[0063] In at least one embodiment, the methane oxidation catalyst comprises a copper zeolite catalyst.

[0064] In at least one embodiment, the methane oxidation catalyst comprises a zeolite catalyst with more than one transition metals used for exchange.

[0065] In at least one embodiment, the methane oxidation catalyst comprises a zeolite catalyst mixed with a supported oxide catalyst.

[0066] In at least one embodiment, the methane oxidation catalyst is a formed catalyst.

[0067] In at least one embodiment, the formed catalyst is in the form of tablets, granules, extrudates, or a combination thereof.

[0068] In at least one embodiment, the catalyst is added to a substrate.

[0069] In at least one embodiment, the catalyst is a combination of coated substrates and formed catalysts.

[0070] In at least one embodiment, the conversion of methane is at least about 25%.

[0071] In at least one embodiment, the conversion of methane is at least about 50%.BRIEF DESCRIPTION OF THE DRAWINGS

[0072] The present disclosure is illustrated by way of example, and not by way of limitation, in the figures of the accompanying drawings, in which:

[0073] FIG. 1 illustrates an exemplary reaction system for performing one or more of the methods described herein according to various embodiments; and

[0074] FIG. 2 illustrates a further exemplary reaction system for performing one or more of the methods described herein according to various embodiments.DEFINITIONS

[0075] As used herein, the singular forms “a,” “an,” and “the” include plural references unless the context clearly indicates otherwise. Thus, for example, reference to “a microsphere” includes a single microsphere as well as a mixture of two or more microspheres, and the like.

[0076] Also as used herein, the term “about” in connection with a measured quantity, refers to the normal variations in that measured quantity, as expected by one of ordinary skill in the art in making the measurement and exercising a level of care commensurate with the objective of measurement and the precision of the measuring equipment. In certain embodiments, the term “about” includes the recited number ±10%, such that “about 10” would include from 9 to 11.

[0077] As used herein, the term “catalyst” or “catalyst composition” or “catalyst material” or “catalyst component” refers to a material that promotes a reaction.

[0078] As used herein, the term “zeolite” refers to a crystalline aluminosilicate with a framework based on an extensive three-dimensional network of silicon, aluminum and oxygen ions and have a substantially uniform pore distribution.

[0079] Recitation of ranges of values herein are merely intended to serve as a shorthand method of referring individually to each separate value falling within the range, unless otherwise indicated herein, and each separate value is incorporated into the specification as if it were individually recited herein. All methods described herein can be performed in any suitable orderunless otherwise indicated herein or otherwise clearly contradicted by context. The use of any and all examples, or exemplary language (e.g., “such as”) provided herein, is intended merely to illuminate certain materials and methods and does not pose a limitation on scope. No language in the specification should be construed as indicating any non-claimed element as essential to the practice of the disclosed materials and methods.DETAILED DESCRIPTION

[0080] This disclosure is directed in certain embodiments to converting methane into CO2. More specifically, certain embodiments relate to providing an initial gas stream including methane, and concentrating the methane in the initial gas stream to produce a concentrated gas stream. The concentrated gas stream includes a methane concentration of at least about 0.2 wt%. The concentrated gas stream can be fed to a reactor including a methane oxidation catalyst to effect conversion of the methane into CO2. Concentrating the methane was found to increase the rate of conversion of the methane into CO2. It has also been found that the use of a copper zeolite catalyst in the methane oxidation catalyst can effectively convert the methane into CO2. Further, the concentrated stream should be no more than 5 wt%, which is right below the flammable level of the stream. By keeping the concentrated stream of methane to this amount, it has been found such concentration can increase the conversion of methane to CO2 in combination with the methane oxidation catalyst described herein.

[0081] FIG. 1 illustrates an exemplary reaction system for performing one or more of the methods described herein according to various embodiments. For example, the system includes a methane concentration system adapted to concentrate methane within a methane-containing gas stream. As shown, the method concentration system comprises a plurality of columns in a simulated moving bed adsorption configuration. For example, at any given time during an adsorption process, one column may be in an adsorption mode for active adsorption of methane, one column may be in a cooling mode, another column may be in a desorption mode to purge the adsorbed methane. During the adsorption mode, an effluent gas stream may contain a low methane concentration (e.g., less than about 5 wt% methane). In some embodiments, ambient air may be used for cooling the column in cooling mode, after which the column may be ready for being used in the adsorption mode. The reaction system further includes a reactor (also referred to as a methane abatement reactor) housing a methane oxidation catalyst adapted to support a methane oxidation reaction. A concentrated gas stream of methane may be red to the reactor for conversion of methane, while an air flow is provided to the reactor that may be used to maintain a target concentration of O2 within the reactor (e.g., less than about 20 wt% during the reaction).In some embodiments, a heated gas flow resulting from the methane oxidation reaction may be used to heat one or more columns during the cooling mode operation.

[0082] FIG. 2 illustrates a further exemplary reaction system for performing one or more of the methods described herein according to various embodiments. In at least one embodiment, a shell and tube configuration reactor may be utilized to generate steam without the use of an external steam generation system. In at least one embodiment, multiple reactor stages may be utilized with intercooler-steam generators depending on the concentration of CF present in the desorbed gas.

[0083] Further aspects of the illustrative reaction system of FIGS. 1 and 2 are described in greater detail below, along with variations thereof.

[0084] In some embodiments, the methane concentration of the concentrated gas stream may be about 0.2 wt% to about 7 wt%. In other embodiments, the methane concentration of the concentrated gas stream may be about 0.25 wt% to about 5 wt%. In another embodiment, the methane concentration of the concentrated gas stream may be about 0.3 wt% to about 1.2 wt%. In yet another embodiment, the methane concentration of the concentrated gas stream may be about 0.35 wt% to about 1 wt%, or about 0.4 wt% to about 0.8 wt%.

[0085] In some embodiments, the methane concentration of the concentrated gas stream may be at least 1.5, at least 5.0, at least 10.0 times greater than the methane concentration of the initial gas stream.

[0086] In some embodiments, the methane concentration of the initial gas stream may be about 0.01 wt% to about 4.6 wt%. In other embodiments, the methane concentration of the initial gas stream may be about 0.1 wt% to about 3 wt%. In another embodiment, the methane concentration of the initial gas stream may be about 0.5 wt% to about 2 wt%. In yet another embodiment, the methane concentration of the initial gas stream may be about 0.8 wt% to about 1.7 wt%, or about 1 wt% to about 1.5 wt%.

[0087] In some embodiments, the conversion of methane in the process may be at least about 25%. In other embodiments, the conversion of methane in the process may be at least about 30%, at least about 35%, at least about 40%, at least about 45%, at least about 50%, at least about 55%, or at least about 60%. In another embodiment, the conversion of methane in the process is about 25% to about 80%, about 30% to about 75%, about 35% to about 70%, about 40% to about 65%, about 45% to about 60%, or about 50% to about 55%.

[0088] In some embodiments, such as in FIG. 2, the reactor assembly may include one or more steps for intercooling. In some embodiments of the method, heat may be removed from a reaction product of the reactor may be used for generating steam.

[0089] In some embodiments of the method, the reactor is an oxidation reactor. The oxidation rector may be in the form of a shell-and-tube heat exchanger with hot oil and / or thermal fluid and / or evaporating water as cooling fluid to provide for heat removal. In some embodiments, the oxidation reactor may have cooling tubes integrated into it to allow for heat removal.

[0090] In some embodiments, the method may further include maintaining an O2 concentration in the reactor from about 10 wt% to less than 21 wt%. In other embodiments, the O2 concentration in the reactor may be maintained at about 10 wt%, at about 12 wt%, at about 14 wt%, at about 16 wt%, at about 18 wt%, or at about 20 wt%. In yet other embodiments, the O2 concentration in the reactor may be maintained from 10 wt% to less than 21 wt%, 11 wt% to 20 wt%, 12 wt% to 19 wt%, 13 wt% to 18 wt%, or 14 wt% to 17 wt%.

[0091] In certain embodiments of the method, concentrating the methane in the initial gas stream may include feeding the initial gas stream to ad adsorption system. In some embodiments the adsorption system may be a simulated moving bed adsorption system. In other embodiments, the adsorption system may be a temperature-swing adsorption system. In another embodiment, the adsorption system may be a pressure-swing adsorption system. In yet another embodiment, the adsorption system may include a clathrate hydrate adsorbent. In another embodiment, the adsorption system may include one or more solid adsorbents selected from zeolites, metal organic frameworks, carbon-based adsorbents, or a combination thereof.

[0092] In some embodiments, the adsorption system may be adapted to cycle between an adsorption stage, a cooling stage, and a desorption stage. In such systems, the method may further include effecting desorption during the desorption stage by transmitting heat from a reaction product of the reactor to the adsorption system.

[0093] In certain embodiments of the method, concentrating the methane may include concentrating the methane using a liquid adsorbent. In certain embodiments of the method, concentrating the methane may include concentrating the methane using a membrane system.

[0094] In certain embodiments of the method, the methane oxidation catalyst may include a copper zeolite catalyst. In some embodiments, the methane oxidation catalyst may include a zeolite catalyst with more than one transition metals used for exchange. In an embodiment, the methane oxidation catalyst may include a zeolite catalyst with one or more transition metals including nickel, iron, cobalt, copper, manganese, vanadium, cerium, zinc, tungsten, molybdenum, platinum, palladium, silver, gold, or a combination thereof.

[0095] In another embodiment, the methane oxidation catalyst may include a zeolite catalyst mixed with a supported oxide catalyst. The supported oxide catalyst may include one or more of zirconia, titania, silica, alumina, or a combination thereof.

[0096] In certain embodiments of the method, the methane oxidation catalyst may be a formed catalyst. The formed catalyst may be in the form of tablets, granules, extrudates, or a combination thereof.

[0097] In certain embodiments of the method, the methane oxidation catalyst may be coated onto a substrate. In another embodiment, the methane oxidation catalyst may be a combination of coated substrates and formed catalysts.

[0098] Exemplary catalysts for use in the conversion of methane that are compatible with the embodiments described herein include the following. International Application Publication No. WO 2008 / 106519, the disclosure of which is hereby incorporated by reference herein in its entirety, describes the multistep synthesis of CuSSZ-13 by two 1 M copper sulfate exchanges into the NEU form of SSZ-13. Synthesis of copper chabazite is also described in Tables 1 and 2 of U.S. Patent No. 8,293,198, the disclosure of which is hereby incorporated by reference herein in its entirety. Base metal catalysts comprising, for example, manganese and copper can be produced as described in U.S. Patent Publication No. 2014 / 0255284, the disclosure of which is hereby incorporated by reference herein in its entirety. Sodium type Y zeolite catalysts can be produced as described, for example, in U.K. Patent Publication No. GB1376250, the disclosure of which is hereby incorporated by reference herein in its entirety.

[0099] Another embodiment of the present disclosure includes a system for converting methane into CO2. The system includes a methane concentration system adapted to concentrate methane within a methane-containing gas stream; and a reactor fluidly coupled to the methane concentration system. The reactor may include a methane oxidation catalyst adapted to support a methane oxidation reaction.

[0100] In some embodiments, the methane concentration system may include a plurality of adsorption columns configured for moving bed adsorption. In some embodiments, at least one of the plurality of adsorption columns may include one or more of a solid adsorbent, a liquid adsorbent, or a clathrate hydrate.

[0101] In some embodiments the solid adsorbent may be a zeolite, a metal organic framework, a carbon material, or a combination thereof. In certain embodiments, the metal organic framework may include [Co3(HCOO)e], [Mg3(HCOO)e], [Mn3(HCOO)e], [Ni3(HCOO)6], [Cu(Me-4py-trz-ia)], MIL-53(A1), MIL-101, UTA-30a, [Cu(INA)2], [Cu(hfipbb)(H2hfipbb)o.5], ROD-8, Ni-L, MOF-5, MOF-177, Cu-BTC, MOF-5, ZIF-8, Mg- MOF-74, Ni-MOF-74, Co-MOF-74, MIL-lOO(Cr), Zn2(5-aip)2(bpy), ATC-Cu, [CO3(C4O4)2(OH)2], Uio-66-Br2, Uio-6, CAU-21-BPDC, CAU-8-BPDC, [Co(ma)(bpy)o.5, [Ni(ma)(bpy)o.5, SBMOF-1, or Al-CDC. In some embodiments, the zeolite may include K- Chabazite, SSZ-13, SAPO-34, Linde 4A, H+mordenite, Na-X, Ca-X, Sr-X, Ba-X, P-zeolite,SAPO-18, SAPO-34, NaETS-4, ZSM-5, MEA(40)-P, Silicalite-1, DD3R, Beta, 5A, 13X, or clinoptilolites. In some embodiments, the carbon material may include Takeda CMS 3 k, MAC, Norit RB 3, ACMs, CACs, activated carbon beads, PRCs, GACs, Acs, SAC -ben, SAC-ben-P- N2, SAC, N-doped porous carbon, OTSS-1-550, or PS-2-450.

[0102] In certain embodiments, the system may be configured to effect desorption of at least one of the adsorption columns during a desorption stage using heat from a methane oxidation reaction product of the reactor. In other embodiments, the system may be configured to cool at least one of the adsorption columns during a cooling stage.

[0103] In certain embodiments, the system may be configured to feed a flow of an Ch- containing gas stream to the reactor to support the methane oxidation reaction.

[0104] In some embodiments, the methane oxidation catalyst may include a copper zeolite catalyst. In other embodiments, the methane oxidation catalyst may include a zeolite catalyst with more than one transition metals used for exchange. In another embodiment, the methane oxidation catalyst may include a zeolite catalyst mixed with a supported oxide catalyst. The supported oxide catalyst may include one or more of zirconia, titania, silica, alumina, or a combination thereof. In yet another embodiment, the methane oxidation catalyst may be a formed catalyst. The formed catalyst may be in the form of tablets, granules, extrudates, or a combination thereof.

[0105] In some embodiments, the catalyst may be added to a substrate. In another embodiment, the catalyst may be a combination of coated substrates and formed catalysts.

[0106] In some embodiments, the conversion of methane in the system is at least about 25%. In other embodiments, the conversion of methane in the system may be at least about 30%, at least about 35%, at least about 40%, at least about 45%, at least about 50%, at least about 55%, or at least about 60%. In another embodiment, the conversion of methane in the system is about 25% to about 80%, about 30% to about 75%, about 35% to about 70%, about 40% to about 65%, about 45% to about 60%, or about 50% to about 55%.

[0107] In some embodiments of the system, the reactor may include two or more vessels with intercooling.

[0108] In certain embodiments of the system, the system may be adapted to generate steam using heat removed from a reaction product of the reactor.

[0109] Certain embodiments of the present disclosure relate to additional system for converting methane into CO2. The additional system may include a methane adsorbent or absorbent adapted to concentrate methane within a methane-containing gas stream; and a methane oxidation catalyst adapted to support a methane oxidation reaction. The methaneadsorbent or absorbent and the methane oxidation catalyst may be contained together within a single vessel.

[0110] In some embodiments, the methane adsorbent or absorbent may include one or more solid adsorbents including zeolites, metal organic frameworks, carbon-based adsorbents, or a combination thereof.[oni] In some embodiments, the vessel may include a membrane system to facilitate concentration and oxidation of methane within the vessel.

[0112] In some embodiments, the system may be configured to feed a flow of an Ch- containing gas stream to the methane oxide catalyst to support the methane oxidation reaction.

[0113] In certain embodiments of the additional system, the methane oxidation catalyst may include a copper zeolite catalyst. In some embodiments, the methane oxidation catalyst may include a zeolite catalyst with more than one transition metal. In some embodiments, the methane oxidation catalyst may include a zeolite catalyst with one or more transition metals comprising nickel, iron, cobalt, copper, manganese, vanadium, cerium, zinc, tungsten, molybdenum, platinum, palladium, silver, gold, or a combination thereof.

[0114] In some embodiments, the methane oxidation catalyst may include a zeolite catalyst with a supported oxide catalyst. The supported oxide catalyst may include one or more of zirconia, titania, silica, alumina, or a combination thereof. In some embodiments, the methane oxidation catalyst may be a formed catalyst. The formed catalyst may be in the form of tablets, granules, extrudates, or a combination thereof.

[0115] In some embodiments of the additional system, the catalyst may be added to a substrate. In another embodiment, the catalyst may be a combination of coated substrates and formed catalysts.

[0116] In some embodiments, the conversion of methane in the system is at least about 25%. In other embodiments, the conversion of methane in the system may be at least about 30%, at least about 35%, at least about 40%, at least about 45%, at least about 50%, at least about 55%, or at least about 60%. In another embodiment, the conversion of methane in the system is about 25% to about 80%, about 30% to about 75%, about 35% to about 70%, about 40% to about 65%, about 45% to about 60%, or about 50% to about 55%.

[0117] A system according to the present disclosure is now described, which may correspond to the systems illustrated in FIGS. 1 and 2, or variants thereof as would be appreciated by those of ordinary skill in the art. It is to understood that this is an exemplary system of the present disclosure, and it is not limited to FIGS. 1 and 2 as described herein. In at least one embodiment, the system includes a methane concentration system and a reactor. In at least one embodiment, The methane concentration system includes a simulated moving bed adsorption systemcomprising a plurality of adsorption columns. The simulated moving bed adsorption can include an adsorption mode column, a cooling mode column and a desorption mode column. As shown in FIGS. 1 and 2, an effluent is feed to the methane concentration system. In at least one embodiment, the effluent includes methane at a concentration of less than 5%. The effluent is then fed into an adsorption column in adsorption mode in the methane concentration system. In this section, the adsorption columns of the methane concentration system include one or more of a solid adsorbent, a liquid absorbent, or a clathrate hydrate adsorbent. When the adsorption column has reached its capacity, the feed can be released and fed into a column in desorption mode. In at least one embodiment, heat is applied to the column in desorption mode using the heat from the methane oxidation reaction product of the reactor in the system. Once desorption is complete, the feed is then cooled in the cooling mode column by applying a feed of ambient air.

[0118] After being cooled, the concentrated methane stream is then fed into the reactor. In at least one embodiment, a single reactor is used (FIG. 1). In at least one embodiment, a two-stage reactor is used (FIG. 2). Each reactor includes a methane oxidation catalyst as described herein. The concentrated methane stream is received by the reactor, and can be concentrated to up to 5 wt% in some embodiments. In at least one embodiment, the reactor is maintained at a temperature of about 50 °C to about 200 °C. In at least one embodiment, a flow of an Ch- containing gas stream is fed to the reactor to support the reaction within, which may contain an Ch content of up to about 20 wt%.ILLUSTRATIVE EXAMPLES

[0119] The following examples are set forth to assist in understanding the disclosure and should not be construed as specifically limiting the invention described and claimed herein. Such variations of the invention, including the substitution of all equivalents now known or later developed, which would be within the purview of those skilled in the art, and changes in formulation or minor changes in experimental design, are to be considered to fall within the scope of the invention incorporated herein.

[0120] The synthesized catalysts were tested in a laboratory test unit under different operating conditions. Experimental data were collected and analyzed, including methane conversion, reactor temperature, and residence time. An exemplary experimental setup included mainly a feed system comprising a plurality of gas or fluid lines that feed into a main line, a preheater fluidly coupled to the main line, a l” tubular reactor with packed catalyst bed downstream from the preheater, a cooling water condenser, and a gas / liquid separator downstream from the packed catalyst bed. The feed system provided both gas and liquidstreams. The preheater could raise the temperature of the feed stream to desired temperature before entering the preheated reactor bed. The reactor bed temperature was controllable by the oil jacket. Both feed and product stream compositions were analyzed by online GC.

[0121] A feed gas containing less than about 0.2% to less than 1% CH4 may be concentrated on a sorbent such that about 4% of total adsorbed gas is in the form of CH4. Sorbents such as ZIF-8, HayeSep, etc. may be used for accomplishing such an adsorption step. The adsorbed methane along with N2 / O2 may then be desorbed using hot gases from the methane oxidation reactor. Upon desorption of such methane, this may result in as much as 2.0%-2.6% CH4 in the gas effluent from the adsorbed bed. This gas may be compressed and passed through a heat exchanger to increase its temperature to -300-350 °C and then fed to a 2-stage methane oxidation reactor (e.g., as illustrated in FIG. 2). The amount of catalyst in each reactor may be adjusted such that the temperature of the effluent from the first reactor does not exceed 550- 650 °C. The methane conversion for this corresponds to about 27-45%. An intercooler between reactors may be used to reduce the temperature back to -350 °C and the heat available may be used for generating steam. A subsequent reactor may then be used for near complete conversion of methane. About 30-35% of the effluent, if recycled, is sufficient to desorb the CH4 from the sorbent bed. Similarly, in order to ensure near complete conversion of CH4, about 10-12% O2 in the recycle gas can be targeted. The lower O2 content ensures that the CF -air mixtures never reach explosive limits. About 65-70% of the reactor effluent gas may be discharged, however, before discharging heat may be recovered from this stream for generating steam.

[0122] In the experimental setup described above, a feed gas containing 0.5% CH4 was also tested at varying gas hourly space velocities (GHSV) and reactor temperature of 425 °C. When a 3.5% Cu-Mordenite catalyst was used, it was observed that while low GHSV gave higher conversion, the conversion decreased with increased GHSV. For example, at a GHSV of 480 h'1the methane conversion was greater than 99%, while at GHSV of 5000 h'1the conversion reduced to about 88%. In order to probe the effect of zeolite structure, a Na-ZSM-5 catalyst with 3.3% Cu was also tested, and for this catalyst 425 °C reaction temperature and 5000 h'1GHSV translated to 81% methane conversion, while >99% conversion was observed at the same temperature and GHSV of 480 h’1. Not wishing to be bound by theory, the slightly lower conversion on Na-ZSM-5 was attributed to -5.7% lower Cu content. However, the strong dependence on Cu content and relative lack of dependence of CH4 conversion on framework structure was unexpected.

[0123] Methane conversion on the 3.3% Cu-exchanged Na-ZSM-5 catalyst was also determined at 425 °C and GHSV of 7500 h'1was also tested and this was observed to be 71%, which was a surprising result. At the relatively low methane concentrations, it was anticipatedthat there would be a relatively linear correlation between methane conversion and residence time, however, the higher conversion at high GHSV could be an unexpected benefit. For example, based on this data, while a 20 m3reactor bed would be needed for converting >99% of the methane in a gas stream with greenhouse gas (GHG) footprint of 3 million tons CCh / y, a relatively small 2.5 m3reactor could yield a modest 2.1 million tons CCh / y GHG reduction for the same gas stream.

[0124] In the foregoing description, numerous specific details are set forth, such as specific materials, dimensions, processes parameters, etc., to provide a thorough understanding of the present invention. The particular features, structures, materials, or characteristics may be combined in any suitable manner in one or more embodiments. The words “example” or “exemplary” are used herein to mean serving as an example, instance, or illustration. Any aspect or design described herein as “example” or “exemplary” is not necessarily to be construed as preferred or advantageous over other aspects or designs. Rather, use of the words “example” or “exemplary” is intended to present concepts in a concrete fashion. As used in this application, the term “or” is intended to mean an inclusive “or” rather than an exclusive “or”. That is, unless specified otherwise, or clear from context, “X includes A or B” is intended to mean any of the natural inclusive permutations. That is, if X includes A; X includes B; or X includes both A and B, then “X includes A or B” is satisfied under any of the foregoing instances. Reference throughout this specification to “an embodiment”, “certain embodiments”, or “one embodiment” means that a particular feature, structure, or characteristic described in connection with the embodiment is included in at least one embodiment. Thus, the appearances of the phrase “an embodiment”, “certain embodiments”, or “one embodiment” in various places throughout this specification are not necessarily all referring to the same embodiment.

[0125] The present disclosure has been described with reference to specific exemplary embodiments thereof. The specification and drawings are, accordingly, to be regarded in an illustrative rather than a restrictive sense. Various modifications of the disclosure in addition to those shown and described herein will become apparent to those skilled in the art and are intended to fall within the scope of the appended claims.

Claims

CLAIMSWhat is claimed is:

1. A method of converting methane into CO2, the method comprising: receiving a concentrated gas stream or concentrating an initial gas stream to produce the concentrated gas stream, wherein the methane concentration of the concentrated gas stream is at least 0.2 wt%; and feeding the concentrated gas stream to a reactor comprising a methane oxidation catalyst to effect conversion of the methane into CO2.

2. The method of claim 1, further comprising: maintaining an O2 concentration in the reactor from about 10 wt% to less than 21 wt%.

3. The method of any of the preceding claims, wherein the methane concentration of the concentrated gas stream is about 0.2 wt% to about 17 wt%.

4. The method of any of the preceding claims, wherein the methane concentration of the concentrated gas stream is about 0.25 wt% to about 5 wt%.

5. The method of any of the preceding claims, wherein the methane concentration of the concentrated gas stream is about 0.3 wt% to about 1.2 wt%.

6. The method of any of the preceding claims, wherein the methane concentration of the concentrated gas stream is at least 1.5, at least 5.0, at least 10.0 times greater than the methane concentration of the initial gas stream.

7. The method of any of the preceding claims, wherein the methane concentration of the initial gas stream is about 0.01 wt% to about 4.6 wt%.

8. The method of any of the preceding claims, wherein the methane concentration of the initial gas stream is about 0.1 wt% to about 3 wt%.

9. The method of any of the preceding claims, wherein the methane concentration of the initial gas stream is about 0.5 wt% to about 2 wt%.

10. The method of any of the preceding claims, wherein the conversion of methane is at least about 25%.

11. The method of any of the preceding claims, wherein the conversion of methane is at least about 50%, is maintained below about 75%, and / or is maintained below about 85%.

12. The method of any of the preceding claims, wherein the reactor comprises two or more vessels with intercooling.

13. The method of any of the preceding claims, wherein heat removed from a reaction product of the reactor is used for generating steam.

14. The method of any of the preceding claims, wherein the oxidation reactor is in the form of a shell-and-tube heat exchanger with hot oil and / or thermal fluid and / or evaporating water as cooling fluid to provide for heat removal.

15. The method of any of the preceding claims, wherein the oxidation reactor has cooling tubes integrated into it to allow for heat removal.

16. The method of any of the preceding claims, wherein concentrating the methane in the initial gas stream comprises feeding the initial gas stream to an adsorption system.

17. The method of claim 16, wherein the adsorption system is a simulated moving bed adsorption system.

18. The method of claim 16, where the adsorption system is a temperature-swing adsorption system.

19. The method of claim 16, wherein the adsorption system is a pressure-swing adsorption system.

20. The method of claim 16, wherein the adsorption system comprises a clathrate hydrate adsorbent.

21. The method of claim 16, wherein the adsorption system comprises one or more solid adsorbents selected from zeolites, metal organic frameworks, carbon-based adsorbents, or a combination thereof.

22. The method of claim 16, wherein the adsorption system is adapted to cycle between an adsorption stage, a cooling stage, and a desorption stage.

23. The method of claim 22, further comprising: effecting desorption during the desorption stage by transmitting heat from a reaction product of the reactor to the adsorption system.

24. The method of any of the preceding claims, wherein concentrating the methane comprises concentrating the methane using a liquid absorbent.

25. The method of any of the preceding claims, wherein concentrating the methane comprises concentrating the methane using a membrane system.

26. The method of any of the preceding claims, wherein the methane oxidation catalyst comprises a copper zeolite catalyst.

27. The method of any of the preceding claims, wherein the methane oxidation catalyst comprises a zeolite catalyst with more than one transition metals used for exchange.

28. The method of claim 27, wherein the methane oxidation catalyst comprises a zeolite catalyst with one or more transition metals comprising nickel, iron, cobalt, copper, manganese, vanadium, cerium, zinc, tungsten, molybdenum, platinum, palladium, silver, gold, or a combination thereof.

29. The method of any of the preceding claims, wherein the methane oxidation catalyst comprises a zeolite catalyst mixed with a supported oxide catalyst.

30. The method of claim 29, wherein the supported oxide catalyst comprises one or more of zirconia, titania, silica, alumina, or a combination thereof.

31. The method of any of the preceding claims, wherein the methane oxidation catalyst is a formed catalyst.

32. The method of claim 31, wherein the formed catalyst is in the form of tablets, granules, extrudates, or a combination thereof.

33. The method of any of the preceding claims wherein the methane oxidation catalyst is coated onto a substrate.

34. The method of any of the preceding claims, wherein the methane oxidation catalyst is a combination of coated substrates and formed catalysts.

35. A system for converting methane into CO2, the system comprising: a methane concentration system adapted to concentrate methane within a methane- containing gas stream; and a reactor fluidly coupled to the methane concentration system, the reactor comprising a methane oxidation catalyst adapted to support a methane oxidation reaction.

36. The system of claim 35, wherein the methane concentration system comprises a plurality of adsorption columns configured for moving bed adsorption.

37. The system of any of claims 35-36, wherein at least one of the plurality of adsorption columns comprises one or more of a solid adsorbent, a liquid absorbent, or a clathrate hydrate adsorbent.

38. The system of claim 36, wherein the system is configured to effect desorption of at least one of the adsorption columns during a desorption stage using heat from a methane oxidation reaction product of the reactor.

39. The system of claim 36, wherein the system is configured to cool at least one of the adsorption columns during a cooling stage.

40. The system of any of claims 35-39, wherein the system is configured to feed a flow of an Ch-containing gas stream to the reactor to support the methane oxidation reaction.

41. The system of claim 35, wherein the methane oxidation catalyst comprises a copper zeolite catalyst.

42. The system of any of claims 35-41, wherein the methane oxidation catalyst comprises a zeolite catalyst with more than one transition metals used for exchange.

43. The system of any of claims 35-42, wherein the methane oxidation catalyst comprises a zeolite catalyst mixed with a supported oxide catalyst.

44. The system of any of claims 35-43, wherein the methane oxidation catalyst is a formed catalyst.

45. The system of claim 44, wherein the formed catalyst is in the form of tablets, granules, extrudates, or a combination thereof.

46. The system of any of claims 35-45, wherein the catalyst is added to a substrate.

47. The system of any of claims 35-46, wherein the catalyst is a combination of coated substrates and formed catalysts.

48. The system of any of claims 35-47, wherein the conversion of methane is at least about 25%.

49. The system of any of claims 35-47, wherein the conversion of methane is at least about 50%, wherein the conversion of methane is maintained below 75%, and / or the conversion of methane is maintained below 85%.

50. The system of claim 49, wherein a bed size of the reactor system is about 5-35% of a bed size of a similar system that is capable of achieving about 99% methane conversion.

51. The system of claim 49, wherein a bed size of the reactor system is from about 1 m3to less than about 10 m3, less than about 8 m3, less than about 6 m3, less than about 4 m3, or less than about 3 m3.

52. The system of any of claims 35-51, wherein the reactor comprises two or more vessels with intercooling.

53. The system of any of claims 35-52, wherein the system is adapted to generate steam using heat removed from a reaction product of the reactor.

54. A system for converting methane into CO2, the system comprising: a methane adsorbent or absorbent adapted to concentrate methane within a methane- containing gas stream; and a methane oxidation catalyst adapted to support a methane oxidation reaction, wherein the methane adsorbent or absorbent and the methane oxidation catalyst are contained together within a single vessel.

55. The system of claim 54, wherein the methane adsorbent or absorbent comprises one or more solid adsorbents comprising zeolites, metal organic frameworks, carbon-based adsorbents, or a combination thereof.

56. The system of any of claims 54-55, wherein the vessel comprise a membrane system to facilitate concentration and oxidation of methane within the vessel.

57. The system of any of claims 54-56, wherein the system is configured to feed a flow of an Ch-containing gas stream to the methane oxide catalyst to support the methane oxidation reaction.

58. The system any of claims 54-57, wherein the methane oxidation catalyst comprises a copper zeolite catalyst.

59. The system of any of claims 54-58, wherein the methane oxidation catalyst comprises a zeolite catalyst with more than one transition metals used for exchange.

60. The system of any of claims 54-59, wherein the methane oxidation catalyst comprises a zeolite catalyst mixed with a supported oxide catalyst.

61. The system of any of claims 54-60, wherein the methane oxidation catalyst is a formed catalyst.

62. The system of claim 61, wherein the formed catalyst is in the form of tablets, granules, extrudates, or a combination thereof.

63. The system of any of claims 54-62, wherein the catalyst is added to a substrate.

64. The system of any of claims 54-63, wherein the catalyst is a combination of coated substrates and formed catalysts.

65. The system of any of claims 54-64, wherein the conversion of methane is at least about 25%.

66. The system of any of claims 54-65, wherein the conversion of methane is at least about 50%.

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