Methods and compositions for decomposition of ammonia

Abstract

In one aspect, the disclosure relates to methods comprising flowing a gas mixture over a catalyst in a reaction chamber; and heating the gas mixture and the catalyst, thereby producing a gaseous product. The disclosure also relates to a composition, comprising hydrogen produced using the methods disclosed herein. The disclosure also relates to a catalyst comprising a structured support; a binder dispersed on the structured support; and a particulate catalyst dispersed on the structured support. This abstract is intended as a scanning tool for purposes of searching in the particular art and is not intended to be limiting of the present disclosure.

Description

METHODS AND COMPOSITIONS FOR DECOMPOSITION OF AMMONIACROSS-REFERENCE TO RELATED APPLICATIONS

[0001] This Application claims the benefit of and priority to U.S. Provisional Application No. 63 / 575,057, filed on April 5, 2024 which is incorporated herein by reference in its entirety.BACKGROUND

[0002] The use of hydrogen (H2) as a fuel source provides a potentially more environmentally sustainable energy alternative to burning hydrocarbons (e.g., oil, natural gas, coal). Current methods for producing hydrogen include processes like methane steam reforming, partial oxidation, and autothermal reforming. Unfortunately, these methods can contribute significantly to CO2emissions, intensifying the global climate crisis. Ammonia has the potential to serve as an energy-dense carrier for storing and transporting renewable hydrogen energy. Despite advances in hydrogen production technology via ammonia decomposition, there is a need for methods and compositions that enable more cost-effective and environmentally sustainable (e.g., carbon neutral and using renewable sources) production of hydrogen. These needs and other needs are satisfied by the present disclosure.SUMMARY

[0003] In accordance with the purpose(s) of the present disclosure, as embodied and broadly described herein, the disclosure, in one aspect, relates a method comprising: flowing a gas mixture over a catalyst in a reaction chamber; and heating the gas mixture and the catalyst, thereby producing a gaseous product; wherein the gas mixture comprises ammonia; and wherein the catalyst comprises a first metallic particle and a second metallic particle dispersed on a support; wherein the support is selected from CeOx, carbon, carbon nanotube, SiC, AI2O3, TiO2, aluminosilicate, and MXene; wherein the first metallic particle is selected from Ru, Co, Fe, and Ni; and wherein the second metallic particle is selected from Cs and K. The disclosure also relates to a composition, comprising hydrogen produced using the methods disclosed herein.

[0004] In another aspect, the disclosure relates to a catalyst, comprising: a structured support; a binder dispersed on the structured support; and a particulate catalyst dispersed on the structured support, wherein the particulate catalyst comprises: a support selected from CeOx, carbon, carbon nanotube, SiC, AI2O3, TiO2, aluminosilicate, and MXene; a first metallic particle dispersed on the support, wherein the first metallic particle is selected from Ru, Co, Fe, and Ni; and a second metallic particle dispersed on the support, wherein the second metallic particle is selected from Cs and K.

[0005] Other systems, methods, features, and advantages of the present disclosure will be or become apparent to one with skill in the art upon examination of the following drawings and detailed description. It is intended that all such additional systems, methods, features, and advantages be included within this description, be within the scope of the present disclosure, and be protected by the accompanying claims. In addition, all optional and preferred features and modifications of the described embodiments are usable in all aspects of the disclosure taught herein. Furthermore, the individual features of the dependent claims, as well as all optional and preferred features and modifications of the described embodiments are combinable and interchangeable with one another.BRIEF DESCRIPTION OF THE DRAWINGS

[0006] Many aspects of the present disclosure can be better understood with reference to the following drawings. The components in the drawings are not necessarily to scale, emphasis instead being placed upon clearly illustrating the principles of the present disclosure. Moreover, in the drawings, like reference numerals designate corresponding parts throughout the several views.

[0007] FIGS. 1A-1B show NH3conversion (FIG. 1A) and H2production (FIG. 1B) at various temperatures for representative microwave-assisted ammonia decomposition using powder catalysts.

[0008] FIGS. 2A-2B show NH3conversion (FIG. 2A) and H2production (FIG. 2B) at various temperatures for representative microwave-assisted ammonia decomposition using a Cs- Fe / CeO2catalyst coated on silicon carbide (SiC) foam using boehmite as a binder.

[0009] FIGS. 3A-3B show NH3conversion (FIG. 3A) and H2production (FIG. 3B) at various temperatures for representative microwave-assisted ammonia decomposition using catalysts coated on SiC foam using boehmite as a binder and a feedstock flow rate of 100 mL / min.

[0010] FIGS. 4A-4B show NH3conversion (FIG. 4A) and H2production (FIG. 4B) at various temperatures for representative microwave-assisted ammonia decomposition using catalysts coated on SiC foam using boehmite as a binder and a feedstock flow rate of 12.6 mL / min.

[0011] FIGS. 5A-5B show NH3conversion (FIG. 5A) and H2production (FIG. 5B) at various temperatures for representative microwave heating or thermal heating ammonia decomposition using a Cs-Ru / CeO2catalyst coated on SiC foam using boehmite as a binder.

[0012] FIGS. 6A-6B show NH3conversion (FIG. 6A) and H2production (FIG. 6B) over time for representative microwave-assisted ammonia decomposition using a Cs-Ru / CeO2catalyst coated on SiC foam using boehmite as a binder.

[0013] FIGS. 7A-7B show NH3conversion (FIG. 7A) and H2production (FIG. 7B) over time for representative microwave-assisted ammonia decomposition using pure boehmite.

[0014] FIGS. 8A-8B show NH3conversion (FIG. 8A) and H2production (FIG. 8B) over time for representative microwave-assisted ammonia decomposition using a Cs-Ru / CeO2catalyst coated on SiC foam using boehmite as a binder and two different feedstock flow rates.

[0015] FIGS. 9A-9B show NH3conversion (FIG. 9A) and H2production (FIG. 9B) over time for representative microwave-assisted ammonia decomposition using a Fe / CeO2(10%) powder catalyst.

[0016] FIGS. 10A-10B show NH3conversion (FIG. 10A) and H2production (FIG. 10B) at various temperatures for representative microwave-assisted ammonia decomposition using a Cs-Ru / CeO2catalyst coated on SiC foam using boehmite or polyvinyl butyral (PVB) as a binder and a feedstock flow rate of 100 mL / min.

[0017] FIGS. 11A-11B show NH3conversion (FIG. 11 A) and H2production (FIG. 11B) at various temperatures for representative microwave-assisted ammonia decomposition using a Cs-Ru / CeO2catalyst coated on SiC foam using boehmite or polyvinyl butyral (PVB) as a binder and a feedstock flow rate of 12.6 mL / min.

[0018] FIGS. 12A-12B show NH3conversion (FIG. 1cA) and H2production (FIG. 1cB) at various temperatures for representative microwave-assisted ammonia decomposition using a Cs-Ru / CeO2catalyst or a Fe / CeO2powder catalyst.

[0019] FIG. 13 illustrates a flow chart for a representative coating procedure of SiC.

[0020] FIGS. 14A-14B show pictures depicting non-coated (blank) SiC foam (FIG. 14A) and coated SiC foam (FIG. 14B).

[0021] FIGS. 15A-15B show NH3conversion (FIG. 15A) and H2production (FIG. 15B) at various temperatures for representative microwave-assisted ammonia decomposition using various catalyst structures and a feedstock flow rate of 100 mL / min.

[0022] FIGS. 16 shows Raman spectra for non-coated SiC foam and coated SiC foam.

[0023] FIGS. 17A-17B show effluent NH3concentration over time for representative microwave-assisted ammonia decomposition using a Cs-Ru / CeO2catalyst (FIG. 17A) and coated SiC foam or non-coated SiC foam (FIG. 17B).

[0024] FIG. 18 shows H2production over time for representative microwave-assisted ammonia decomposition using various catalyst structures.

[0025] FIG. 19 shows effluent NH3concentration at various temperatures for representativemicrowave-assisted ammonia decomposition using two different catalyst structures.

[0026] Additional advantages of the disclosure will be set forth in part in the description which follows, and in part will be obvious from the description, or can be learned by practice of the disclosure. The advantages of the disclosure will be realized and attained by means of the elements and combinations particularly pointed out in the appended claims. It is to be understood that both the foregoing general description and the following detailed description are exemplary and explanatory only and are not restrictive of the disclosure, as claimed.DETAILED DESCRIPTION

[0027] Many modifications and other embodiments disclosed herein will come to mind to one skilled in the art to which the disclosed compositions and methods pertain having the benefit of the teachings presented in the foregoing descriptions and the associated drawings. Therefore, it is to be understood that the disclosures are not to be limited to the specific embodiments disclosed and that modifications and other embodiments are intended to be included within the scope of the appended claims. The skilled artisan will recognize many variants and adaptations of the aspects described herein. These variants and adaptations are intended to be included in the teachings of this disclosure and to be encompassed by the claims herein.

[0028] Although specific terms are employed herein, they are used in a generic and descriptive sense only and not for purposes of limitation.

[0029] As will be apparent to those of skill in the art upon reading this disclosure, each of the individual embodiments described and illustrated herein has discrete components and features which may be readily separated from or combined with the features of any of the other several embodiments without departing from the scope or spirit of the present disclosure.

[0030] Any recited method can be carried out in the order of events recited or in any other order that is logically possible. That is, unless otherwise expressly stated, it is in no way intended that any method or aspect set forth herein be construed as requiring that its steps be performed in a specific order. Accordingly, where a method claim does not specifically state in the claims or descriptions that the steps are to be limited to a specific order, it is no way intended that an order be inferred, in any respect. This holds for any possible non-express basis for interpretation, including matters of logic with respect to arrangement of steps or operational flow, plain meaning derived from grammatical organization or punctuation, or the number or type of aspects described in the specification.

[0031] All publications mentioned herein are incorporated herein by reference to disclose and describe the methods and / or materials in connection with which the publications are cited.The publications discussed herein are provided solely for their disclosure prior to the filing date of the present application. Nothing herein is to be construed as an admission that the present invention is not entitled to antedate such publication by virtue of prior invention. Further, the dates of publication provided herein can be different from the actual publication dates, which can require independent confirmation.

[0032] While aspects of the present disclosure can be described and claimed in a particular statutory class, such as the system statutory class, this is for convenience only and one of skill in the art will understand that each aspect of the present disclosure can be described and claimed in any statutory class.

[0033] It is also to be understood that the terminology used herein is for the purpose of describing particular aspects only and is not intended to be limiting. Unless defined otherwise, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which the disclosed compositions and methods belong. It will be further understood that terms, such as those defined in commonly used dictionaries, should be interpreted as having a meaning that is consistent with their meaning in the context of the specification and relevant art and should not be interpreted in an idealized or overly formal sense unless expressly defined herein.

[0034] Prior to describing the various aspects of the present disclosure, the following definitions are provided and should be used unless otherwise indicated. Additional terms may be defined elsewhere in the present disclosure.A. DEFINITIONS

[0035] As used herein, “comprising” is to be interpreted as specifying the presence of the stated features, integers, steps, or components as referred to, but does not preclude the presence or addition of one or more features, integers, steps, or components, or groups thereof. Moreover, each of the terms “by”, “comprising,” “comprises”, “comprised of,” “including,” “includes,” “included,” “involving,” “involves,” “involved,” and “such as” are used in their open, non-limiting sense and may be used interchangeably. Further, the term “comprising” is intended to include examples and aspects encompassed by the terms “consisting essentially of’ and “consisting of.” Similarly, the term “consisting essentially of’ is intended to include examples encompassed by the term “consisting of.

[0036] As used in the specification and the appended claims, the singular forms “a,” “an” and “the” include plural referents unless the context clearly dictates otherwise. Thus, for example, reference to “an olefin,” “a fuel,” or “a temperature,” including, but not limited to, two or more such olefins, fuels, or temperatures, and the like.

[0037] It should be noted that ratios, concentrations, amounts, and other numerical data can be expressed herein in a range format. It will be further understood that the endpoints of each of the ranges are significant both in relation to the other endpoint, and independently of the other endpoint. It is also understood that there are a number of values disclosed herein, and that each value is also herein disclosed as “about” that particular value in addition to the value itself. For example, if the value “10” is disclosed, then “about 10” is also disclosed. Ranges can be expressed herein as from “about” one particular value, and / or to “about” another particular value. Similarly, when values are expressed as approximations, by use of the antecedent “about,” it will be understood that the particular value forms a further aspect. For example, if the value “about 10” is disclosed, then “10” is also disclosed.

[0038] When a range is expressed, a further aspect includes from the one particular value and / or to the other particular value. For example, where the stated range includes one or both of the limits, ranges excluding either or both of those included limits are also included in the disclosure, e.g. the phrase “xto y” includes the range from ‘x’ to ‘y’ as well as the range greater than x’ and less than ‘y’. The range can also be expressed as an upper limit, e.g. ‘about x, y, z, or less’ and should be interpreted to include the specific ranges of ‘about x’, ‘about y’, and ‘about z’ as well as the ranges of ‘less than x’, less than y’, and ‘less than z’. Likewise, the phrase ‘about x, y, z, or greater’ should be interpreted to include the specific ranges of ‘about x’, ‘about y’, and ‘about z’ as well as the ranges of ‘greater than x’, greater than y’, and ‘greater than z’. In addition, the phrase “about ‘x’ to ‘y’”, where ‘x’ and ‘y’ are numerical values, includes “about x’ to about ‘y’”.

[0039] It is to be understood that such a range format is used for convenience and brevity, and thus, should be interpreted in a flexible manner to include not only the numerical values explicitly recited as the limits of the range, but also to include all the individual numerical values or sub-ranges encompassed within that range as if each numerical value and sub-range is explicitly recited. To illustrate, a numerical range of “about 0.1% to 5%” should be interpreted to include not only the explicitly recited values of about 0.1 % to about 5%, but also include individual values (e.g., about 1 %, about 2%, about 3%, and about 4%) and the sub-ranges (e.g., about 0.5% to about 1.1 %; about 5% to about 2.4%; about 0.5% to about 3.2%, and about 0.5% to about 4.4%, and other possible sub-ranges) within the indicated range.

[0040] As used herein, the terms “about,” “approximate,” “at or about,” and “substantially” mean that the amount or value in question can be the exact value or a value that provides equivalent results or effects as recited in the claims or taught herein. That is, it is understood that amounts, sizes, formulations, parameters, and other quantities and characteristics are not and need not be exact, but may be approximate and / or larger or smaller, as desired, reflectingtolerances, conversion factors, rounding off, measurement error and the like, and other factors known to those of skill in the art such that equivalent results or effects are obtained. In some circumstances, the value that provides equivalent results or effects cannot be reasonably determined. In such cases, it is generally understood, as used herein, that “about” and “at or about” mean the nominal value indicated ±10% variation unless otherwise indicated or inferred. In general, an amount, size, formulation, parameter or other quantity or characteristic is “about,” “approximate,” or “at or about” whether or not expressly stated to be such. It is understood that where “about,” “approximate,” or “at or about” is used before a quantitative value, the parameter also includes the specific quantitative value itself, unless specifically stated otherwise.

[0041] As used herein, the term “effective amount” refers to an amount that is sufficient to achieve the desired modification of a physical property of the composition or material. For example, an “effective amount” of a temperature refers to an amount that is sufficient to achieve the desired improvement in the property modulated by the formulation component, e.g. achieving the desired level of modulus. The specific level in terms of wt% in a composition required as an effective amount will depend upon a variety of factors including the amount and type of olefin that is desired, amount and type of fuel that is desired, and economic considerations.

[0042] As used herein, the terms “optional” or “optionally” means that the subsequently described event or circumstance can or cannot occur, and that the description includes instances where said event or circumstance occurs and instances where it does not.

[0043] As used herein, the term “MXene” refers to a 2D material comprising carbides and nitrides of transition metals. MXenes comprise n+1 layers of transition metals (M), where n is an integer ranging from 1 to 4, interleaved with n layers of carbon, nitrogen, or a combination thereof. The 2D MXene structure can also include elemental surface terminations (Tx) bonded to the outer M layers of the structure. MXenes can be represented by the generic formula Mn+iXnTx, where M is a transition metal (e.g., Ti, V, Cr, Y, Zr, Nb, Mo, Hf, Ta, W, or a combination thereof); X is carbon, nitrogen, or a combination thereof; and Txis a surface termination that can be — O, — OH, — F, and / or — Cl. Examples of MXenes include Ti3C2Tx, Ti2CTx, XACTx, Mo2Ti2C3Tx, M02TiC2Tx, Cr2TiC2Tx, MO2CNTX, and the like.

[0044] As used herein, the term “carbon nitride” or “CNX” refers to a polymeric material with a repeating unit having a C:N ratio represented by x (e.g., C3N4has a 3:4 carbon to nitrogen ratio). These materials can have a variety of structures and C:N ratios. Examples of carbon nitride materials include C2N, polyaniline C3N, all-triazine-based C3N3, porous g-C3N4, a-C3N4, P-C3N4, cubic C2N4, triazine-based C3N5, C3N5, C3N6, C3N7, and the like.

[0045] As used herein, the term “CeOx” refers to a material that comprises Ce3+ions (Ce2O3) or Ce4+ions (CeO2). CeOxcan also referto a material that comprises a heterogeneous mixture of Ce ions, including Ce3+(Ce2O3) and Ce4+(CeO2).

[0046] Unless otherwise specified, pressures referred to herein are based on atmospheric pressure (i.e. one atmosphere).B. ABBREVIATIONS

[0047] PVB polyvinyl butyral

[0048] SiC silicon carbideC. DISCUSSION

[0049] The use of molecular hydrogen (H2) as a fuel source has many benefits, as it is a more environmentally sustainable energy alternative to burning hydrocarbons (e.g., oil, natural gas, and coal). H2is an attractive fuel option for transportation and electricity generation as it can be used in cars / buses, in houses / commercial structures, for portable power generation, and in many additional applications. H2can be produced from a variety of resources, including natural gas, nuclear power, biomass, and renewable power (e.g., solar, wind). Two primary methods of producing H2include steam methane reforming (SMR) and electrolysis of water. The SMR process emits significant volumes of greenhouse gas (GHG) and carbon dioxide (CO2), nullifying H2’s eco-credentials. Alternatively, water electrolysis is energy-intensive and expensive.

[0050] NH3decomposition has been explored as a method for generating H2. The gravimetric H2capacity of NH3is ~17.6-17.8 wt % and its volumetric H2density (121 kgH2m-3in liquid ammonia) is ~1 .4 times higher than that of liquid hydrogen. An advantage of NH3as a future H2carrier is that it is already commercially produced on a megaton (Mt) scale with primary use in fertilizer production, and it can be transported in pipelines. Typical decomposition of NH3is carried out at high temperatures (e.g., 400 °C - 500 °C and up to 1000 °C). In contrast, the methods of the present disclosure are carried out at significantly reduced temperatures. The methods of the present disclosure can also be carried out at low pressures and using microwave decomposition, resulting in lower operational costs. Additionally, the decomposition methods of the present disclosure can be powered by renewable energy sources.

[0051] The extraction of hydrogen from ammonia involves catalytic decomposition, the reverse reaction of ammonia synthesis. The primary challenge in ammonia decomposition lies in the high temperature required for breaking down ammonia into H2and N2. The methodsand compositions disclosed herein address this challenge by enabling ammonia production at relatively low temperatures (e.g., 360 °C) under microwave irradiation, achieving ammonia conversion rates of up to and exceeding 99%. In one aspect, the disclosed methods and compositions provide improved low temperature and high conversion performance and also demonstrate the capability of producing green H2. In one aspect, the methods and compositions disclosed herein can contribute towards a low-carbon energy landscape.

[0052] A reaction scheme for the decomposition of ammonia is provided below:NH3« 3H2+ N2, AH° = 46.22 kj / molD. METHODS FOR AMMONIA DECOMPOSITION

[0053] Briefly, the present disclosure pertains to methods comprising heating of a catalyst to decompose ammonia feedstock into hydrogen and nitrogen. In one aspect, the method comprises: flowing a gas mixture over a catalyst in a reaction chamber; and heating the gas mixture and the catalyst, thereby producing a gaseous product. In a further aspect, the gas mixture comprises ammonia. In another further aspect, the catalyst can comprise a first metallic particle and a second metallic particle dispersed on a support, wherein the support can be selected from CeOx(e.g., CeCh), carbon, carbon nanotube, SiC, AI2O3, TiC>2, aluminosilicate (such as zeolite, an aluminosilicate molecular sieve), and MXene. In another further aspect, the first metallic particle can be selected from Ru, Co, Fe, and Ni and the second metallic particle can be selected from Cs and K. When the support is zeolite, the specific zeolite material can be, for example, a pentasil zeolite such as Zeolite Socony Mobil (ZSM)-5 or a faujasite-type structure zeolite such as Zeolite X, Zeolite Y, or Zeolite 13X. Zeolites are hydrated aluminosilicate minerals comprising interconnected alumina (AIO4) and silica tetrahedra (SiO4). Zeolites have the general formula [(SiO2)(AIO2)x]n+x / rw H2O, where M is a cation with positive charge n (where n is 1 , 2, or 3), x represents the Si: Al atomic ratio, and w is the number of water molecules in the zeolite structure. In one aspect, the method can be performed at about atmospheric pressure. In another aspect, the method can be performed at a pressure of about 0.5 atm to about 45 atm, about 0.5 atm to about 35 atm, about 0.5 atm to about 25 atm, about 0.5 atm to about 15 atm, about 0.5 atm to about 5 atm, about 1 atm to about 45 atm, about 1 atm to about 40 atm, about 1 atm to about 30 atm, about 1 atm to about 20 atm, about 1 atm to about 10 atm, or about 1 atm to about 5 atm. Advantages of the methods and processes of the present disclosure can include: (a) production of renewable H2at low pressures and temperatures, (b) the potential for a significantly or fully green production of H2with little to no carbon emission, (c) high feedstock conversion, and / or (d) efficient and scalable methods and processes for H2production.

[0054] In one aspect, a reaction chamber can include any chamber in which a controlled chemical reaction can take place. The reaction chamber can be in fluid communication with a gas mixture source comprising ammonia, allowing the gas mixture to enter into the chamber. The gas mixture entry or injection into the chamber can be accomplished using a gas delivery system that is in gaseous communication (e.g., via tubing, valves, pressure regulators, and the like.) with the chamber. The gas delivery system can include a source of ammonia, such as a pressurized ammonia cylinder or a gaseous mixture including ammonia. The reaction chamber can also be configured to allow the gaseous product to exit the chamber and, optionally, be collected outside of the chamber. In one aspect, the reaction chamber can be configured to allow the pressure in the chamber to be increased above or decreased below atmospheric pressure (e.g., by sealing and pressurizing the chamber). Examples of reaction chambers include a pressure reactor, a pressure vessel, a high temperature reaction chamber, and a single reaction chamber. In one aspect, the reaction chamber can comprise a non- reactive material. In another aspect, the reaction chamber can comprise stainless steel, aluminum, titanium, a fluoropolymer (e.g., polytetrafluoroethylene), and the like, or a combination thereof.

[0055] The catalyst can comprise the first metallic particle and the second metallic particle individually dispersed on the support. In one aspect, the total weight of the catalyst can be from about 1 wt.% to about 15 wt.%, about 1 wt.% to about 10 wt%, about 1 wt.% to about 5 wt%, about 5 wt.% to about 15 wt%, or about 5 wt.% to about 10 wt% of the total weight of the first metallic particle and the second metallic particle. In another aspect, the method can result in about 50% to 100%, about 60% to 100%, about 70% to 100%, about 80% to 100%, about 90% to 100%, about 90% to about 100%, about 93% to about 100%, about 95% to about 100%, about 97% to about 100%, about 95% to 100%, or about 97% to 100% conversion of ammonia in the gas mixture to hydrogen and nitrogen.

[0056] In another aspect, the catalyst can further comprise a structured support and a binder. For example, the catalyst can comprise a first particulate structure and the binder dispersed on the structured support, where the first particulate structure (e.g., particulate catalyst) includes the first metallic particle, the second metallic particle, and the support. The structured support can be a monolithic support or a structured foam support. The structured support or can comprise or be formed from, for example, SiC or CeO2. A monolithic support, as used herein, refers to an extruded structure that comprises a plurality of channels running axially through the support. These channels can have various shapes, such as a polygonal channel (e.g., a honeycomb structure). A structured foam, as used herein, refers to a structure comprising a plurality of open pores (for example, from about 10 pores to 100 pores per inchof the structure) and an interconnected porosity in the range of about 75% to about 90%. Interconnected porosity refers to the ratio of the volume of void space within a material (that is accessible from the exterior) to the total volume of the material.

[0057] The binder can comprise boehmite, polyvinyl butyral, aluminum hydroxide, silicate hydrate, or a combination thereof. In one aspect, the total weight of the catalyst can be from about 1 wt.% to about 10 wt%, about 1 wt.% to about 5 wt%, about 5 wt.% to about 10 wt.%, about 3 wt.% to about 10 wt%, about 1 wt.% to about 7 wt.%, or about 3 wt.% to about 7 wt% of the total weight of the first metallic particle, the second metallic particle, the support, and the binder. In another aspect, the total weight of the catalyst can be from about 90 wt.% to about 99 wt.%, about 95 wt.% to about 99 wt.%, about 90 wt.% to about 95 wt.%, about 90 wt.% to about 97 wt.%, about 93 wt.% to about 99 wt.%, or about 93 wt.% to about 97 wt.% of the total weight of the structured support.

[0058] In one aspect, the gas mixture and the catalyst can be heated to a temperature ranging from about 100 °C to about 600 °C, about 100 °C to about 550 °C, about 100 °C to about 500°C, about 100 °C to about 450 °C, about 100 °C to about 400 °C, about 100 °C to about 350°C, about 100 °C to about 300 °C, about 150 °C to about 600 °C, about 200 °C to about 600°C, about 250 °C to about 600 °C, about 200 °C to about 550 °C, about 200 °C to about 500°C, about 250 °C to about 550 °C, or about 250 °C to about 500 °C. The heating can be carried out by heating the reaction chamber using conventional thermal heating methods, such as heating a fluid or solid (e.g., air, oil, or sand) that is in contact with the reaction vessel or using a heating mantle. In another aspect, the heating can be carried out by more direct heating of the catalyst using microwave irradiation. The conditions under which the microwave radiation is applied (e.g., period of time, frequency, power) can be selected to maximize the decomposition of ammonia. For example, the catalyst can be heated using microwave irradiation with an output power of 1 KW at 2.45 GHz for a period of time long enough for the desired decomposition of ammonia (e.g., from about 1 s to about 10 min, from about 0.5 min to about 10 min, from about 0.5 min to about 8 min, or from about 1 min to about 5 min). The source of microwave radiation can be, for example, a commercially available microwave oven or a solid-state microwave generator. In one aspect, the microwave heating or thermal heating can be powered by renewable energy sources.

[0059] The flow rate of the gas mixture can be varied depending on the amount of catalyst present in the reaction chamber. For example, the flow rate of the gas mixture can range from about 10 mL / min to about 1000 mL / min per one milliliter of catalyst in the reaction chamber. For example, for a reaction chamber including one milliliter of the catalyst, the flow rate chosen can range from about 10 mL / min to about 1000 mL / min, about 10 mL / min to about 600 mL / min,about 10 mL / min to about 300 mL / min, about 100 mL / min to about 1000 mL / min, about 100 mL / min to about 600 mL / min, or about 100 mL / min to about 300 mL / min. In one aspect, the gas mixture can further comprise an inert gas. The gas mixture can further include an inert gas when, for example, the reaction chamber or any components in fluid communication with the reaction chamber are sensitive to ammonia (i.e., can be damaged or corroded by contact with ammonia). The inert gas can be selected from helium, argon, nitrogen, and any combination thereof. In another aspect, the inert gas can be free of oxygen.

[0060] As a specific example, a microwave selective heating process can be run at a microwave frequency of 2.45 GHz using a Cs-Ru / CeO2catalyst with a flowing gas feedstock mixture of 15 vol. % NH3and 85 vol. % Helium. The Cs-Ru / CeO2(2-4 wt%) catalyst, i.e., in which Cs was present as 2 wt% and Ru as 4 wt% based on the total weight of the catalyst (Cs, Ru and CeO2), was initially heated at ambient pressure to a temperature of 260 °C for a 30-minute period. Then, the temperature was incrementally increased to 300 °C, then 340 °C, and then 360 °C at 30-minute intervals. This heating resulting in a cumulative NH3decomposition of approximately 100% at 360 °C.E. CATALYSTS FOR AMMONIA DECOMPOSITION

[0061] Also disclosed herein is a catalyst, comprising: a structured support; a binder dispersed on the structured support; and a particulate catalyst dispersed on the structured support. The particulate catalyst can comprise: a support selected from CeOx(e.g., CeO2), carbon, carbon nanotube, SiC, AI2O3, TiO2, aluminosilicate (such as zeolite, an aluminosilicate molecular sieve), and MXene; a first metallic particle dispersed on the support, wherein the first metallic particle is selected from Ru, Co, Fe, and Ni; and a second metallic particle dispersed on the support, wherein the second metallic particle is selected from Cs and K. When the support is zeolite, the specific zeolite material can be, for example, a pentasil zeolite such as Zeolite Socony Mobil (ZSM)-5 or a faujasite-type structure zeolite such as Zeolite X, Zeolite Y, or Zeolite 13X.

[0062] The particulate catalyst can comprise the first metallic particle and the second metallic particle individually dispersed on the support. In one aspect, the total weight of the particulate catalyst can be from about 1 wt.% to about 15 wt.%, about 1 wt.% to about 10 wt%, about 1 wt.% to about 5 wt%, about 5 wt.% to about 15 wt%, or about 5 wt.% to about 10 wt% of the total weight of the first metallic particle and the second metallic particle. In another aspect, the particulate catalyst can be a powder catalyst.

[0063] In one aspect, the particulate catalyst can be dispersed on the structured support. In another aspect, the binder can be dispersed on the structured support. The structured supportcan be a monolithic support or a structured foam support. The structured support or can be formed, for example, from SiC or CeO2. The binder can comprise boehmite, polyvinyl butyral, aluminum hydroxide, silicate hydrate, or a combination thereof. In one aspect, the total weight of the catalyst can be from about 1 wt.% to about 10 wt%, about 1 wt.% to about 5 wt%, about 5 wt.% to about 10 wt.%, about 3 wt.% to about 10 wt%, about 1 wt.% to about 7 wt.%, or about 3 wt.% to about 7 wt% of the total weight of the particulate catalyst and the binder. In another aspect, the total weight of the catalyst can be from about 90 wt.% to about 99 wt.%, about 95 wt.% to about 99 wt.%, about 90 wt.% to about 95 wt.%, about 90 wt.% to about 97 wt.%, about 93 wt.% to about 99 wt.%, or about 93 wt.% to about 97 wt.% of the total weight of the structured support.

[0064] As a specific example, a microwave selective heating process can be run at a microwave frequency of 2.45 GHz using a Cs-Ru / CeO2catalyst with a flowing gas feedstock mixture of 15 vol. % NH3 and 85 vol. % Helium. The Cs-Ru / CeC>2 (2-4 wt%) catalyst, i.e., in which Cs was present as 2 wt% and Ru as 4 wt% based on the total weight of the catalyst (Cs, Ru and CeO2), was initially heated at ambient pressure to a temperature of 260 °C for a 30-minute period. Then, the temperature was incrementally increased to 300 °C, then 340 °C, and then 360 °C at 30-minute intervals. This heating resulting in a cumulative NH3decomposition of approximately 100% at 360 °C.F. ASPECTS

[0065] The following listing of exemplary aspects supports and is supported by the disclosure provided herein.

[0066] Aspect 1 . A method comprising: flowing a gas mixture over a catalyst in a reaction chamber; and heating the gas mixture and the catalyst, thereby producing a gaseous product; wherein the gas mixture comprises ammonia; and wherein the catalyst comprises a first metallic particle and a second metallic particle dispersed on a support; wherein the support is selected from CeOx, carbon, carbon nanotube, SiC, AI2O3, TiO2, aluminosilicate, and MXene; wherein the first metallic particle is selected from Ru, Co, Fe, and Ni; and wherein the second metallic particle is selected from Cs and K.

[0067] Aspect 2. The method of aspect 1 , wherein the gas mixture has a flow rate of from about 10 mL / min to about 1000 mL / min per one milliliter of the catalyst.

[0068] Aspect s. The method of aspect 1 or aspect 2, wherein the gas mixture and the catalyst are heated to a temperature ranging from about 100 °C to about 600 °C.

[0069] Aspect 4. The method of aspect 1 or aspect 2, wherein the gas mixture and the catalyst are heated to a temperature ranging from about 250 °C to about 500 °C.

[0070] Aspect 5. The method of any one of aspects 1-4, wherein the gas mixture and the catalyst are heated using microwave irradiation.

[0071] Aspect 6. The method of any one of aspects 1-4, wherein the gas mixture and the catalyst are heated using thermal heating.

[0072] Aspect 7. The method of any one of aspects 1-6, wherein the method is carried out at a pressure of about 0.5 atm to about 45 atm.

[0073] Aspect 8. The method of any one of aspects 1-6, wherein the method is carried out at a pressure of about 1 atm to about 10 atm.

[0074] Aspect 9. The method of any one of aspects 1-8, wherein the first metallic particle is selected from Ru and Fe.

[0075] Aspect 10. The method of any one of aspects 1 -9, wherein the support is selected from CeO2, carbon nanotube, SiC, AI2O3, TiO2, and a zeolite.

[0076] Aspect 11 . The method of aspect 10, wherein the support is a zeolite selected from a pentasil zeolite and a faujasite-type structure zeolite.

[0077] Aspect 12. The method of any one of aspects 1-11 , wherein the catalyst comprises from about 1 wt.% to about 15 wt.% the first metallic particle and the second metallic particle.

[0078] Aspect 13. The method of any one of aspects 1-11 , wherein the catalyst comprises from about 1 wt.% to about 10 wt.% the first metallic particle and the second metallic particle.

[0079] Aspect 14. The method of any one of aspects 1-13, wherein the catalyst further comprises a structured support and a binder.

[0080] Aspect 15. The method of aspect 14, wherein the structured support is a monolithic support or a foam.

[0081] Aspect 16. The method of aspect 14 or aspect 15, wherein the structured support comprises SiC.

[0082] Aspect 17. The method of any one of aspects 14-16, wherein the binder comprises boehmite, polyvinyl butyral, aluminum hydroxide, silicate hydrate, or a combination thereof.

[0083] Aspect 18. The method of any one of aspects 14-17, wherein the catalyst comprises from about 1 wt.% to about 10 wt.% of the first metallic particle, the second metallic particle, the support, and the binder.

[0084] Aspect 19. The method of any one of aspects 14-17, wherein the catalyst comprises from about 1 wt.% to about 5 wt.% of the first metallic particle, the second metallic particle, the support, and the binder.

[0085] Aspect 20. The method of any one of aspects 14-19, wherein the catalyst comprises from about 90 wt.% to about 99 wt.% of the structured support.

[0086] Aspect 21 . The method of any one of aspects 14-19, wherein the catalyst comprises from about 95 wt.% to about 99 wt.% of the structured support.

[0087] Aspect 22. The method of any one of aspects 1-21 , wherein the gaseous product comprises hydrogen and nitrogen.

[0088] Aspect 23. The method of any one of aspects 1-22, wherein the method results in about 50% to 100% conversion of ammonia in the gas mixture to hydrogen and nitrogen.

[0089] Aspect 24. The method of any one of aspects 1-22, wherein the method results in about a 90% to about 100% conversion of ammonia in the gas mixture to hydrogen and nitrogen.

[0090] Aspect 25. A composition, comprising hydrogen produced using the method of any one of aspects 1-24.

[0091] Aspect 26. A catalyst, comprising: a structured support; a binder dispersed on the structured support; and a particulate catalyst dispersed on the structured support, wherein the particulate catalyst comprises: a support selected from CeOx, carbon, carbon nanotube, SiC, AI2O3, TiO2, aluminosilicate, and MXene; a first metallic particle dispersed on the support, wherein the first metallic particle is selected from Ru, Co, Fe, and Ni; and a second metallic particle dispersed on the support, wherein the second metallic particle is selected from Cs and K.

[0092] Aspect 27. The catalyst of aspect 26, wherein the structured support is a monolithic support or a structured foam.

[0093] Aspect 28. The catalyst of aspect 26 or aspect 27, wherein the structured support comprises SiC.

[0094] Aspect 29. The catalyst of any one of aspects 26-28, wherein the first metallic particle is selected from Ru and Fe.

[0095] Aspect 30. The catalyst of any one of aspects 26-29, wherein the support is selected from CeO2, carbon nanotube, SiC, AI2O3, TiO2, and a zeolite.

[0096] Aspect 31. The catalyst of aspect 30, wherein the support is a zeolite selected from a pentasil zeolite and a faujasite-type structure zeolite.

[0097] Aspect 32. The catalyst of any one of aspects 26-31 , wherein the particulate catalyst comprises from about 1 wt.% to about 15 wt.% the first metallic particle and the second metallic particle.

[0098] Aspect 33. The catalyst of any one of aspects 26-31 , wherein the particulate catalyst comprises from about 1 wt.% to about 10 wt.% the first metallic particle and the second metallic particle.

[0099] Aspect 34. The catalyst of any one of aspects 26-33, wherein the binder comprises boehmite, polyvinyl butyral, aluminum hydroxide, silicate hydrate, or a combination thereof.

[0100] Aspect 35. The catalyst of any one of aspects 26-34, wherein the catalyst comprises from about 1 wt.% to about 10 wt.% of the particulate catalyst and the binder.

[0101] Aspect 36. The catalyst of any one of aspects 26-34, wherein the catalyst comprises from about 1 wt.% to about 5 wt.% of the particulate catalyst and the binder.

[0102] Aspect 37. The catalyst of any one of aspects 26-35, wherein the catalyst comprises from about 90 wt.% to about 99 wt.% of the structured support.

[0103] Aspect 38. The catalyst of any one of aspects 26-35, wherein the catalyst comprises from about 95 wt.% to about 99 wt.% of the structured support.

[0104] From the foregoing, it will be seen that aspects herein are well adapted to attain all the ends and objects hereinabove set forth together with other advantages which are obvious and which are inherent to the structure.

[0105] While specific elements and steps are discussed in connection to one another, it is understood that any element and / or steps provided herein is contemplated as being combinable with any other elements and / or steps regardless of explicit provision of the same while still being within the scope provided herein.

[0106] It will be understood that certain features and subcombinations are of utility and may be employed without reference to other features and subcombinations. This is contemplated by and is within the scope of the claims.

[0107] Since many possible aspects may be made without departing from the scope thereof, it is to be understood that all matter herein set forth or shown in the accompanying drawings and detailed description is to be interpreted as illustrative and not in a limiting sense.

[0108] It is also to be understood that the terminology used herein is for the purpose of describing particular aspects only, and is not intended to be limiting. The skilled artisan will recognize many variants and adaptations of the aspects described herein. These variants and adaptations are intended to be included in the teachings of this disclosure and to be encompassed by the claims herein.

[0109] Now having described the aspects of the present disclosure, in general, the following Examples describe some additional aspects of the present disclosure. While aspects of the present disclosure are described in connection with the following examples and the corresponding text and figures, there is no intent to limit aspects of the present disclosure to this description. On the contrary, the intent is to cover all alternatives, modifications, and equivalents included within the spirit and scope of the present disclosure.G. EXAMPLES

[0110] The following examples are put forth so as to provide those of ordinary skill in the art with a complete disclosure and description of how the compounds, compositions, articles, devices and / or methods claimed herein are made and evaluated, and are intended to be purely exemplary of the disclosure and are not intended to limit the scope of what the inventors regard as their disclosure. Efforts have been made to ensure accuracy with respect to numbers (e.g., amounts, temperature, etc.), but some errors and deviations should be accounted for. Unless indicated otherwise, parts are parts by weight, temperature is in °C or is at ambient temperature, and pressure is at or near atmospheric.1. Methods for Preparing Powder Catalysts and SIC Foam Catalysts

[0111] This Example provides a general overview of the production of a Cs-Ru / CeC>2 catalyst. All chemicals were purchased from Sigma Aldrich: Ruthenium (III) Nitrosyl nitrate (Ru [NO][NO3]3, RU 31.3% min), Cesium Nitrate (CsNO3, 99.8% metals basis), and Cerium oxide (50 nm nano-powder, >99.95%). Cs-Ru / CeO2catalysts were prepared using the incipient wetness impregnation method. Briefly, a known mass of 1 ,2g CeO2support was impregnated with 2 wt.% CSNO3and 4 wt.% Ru[NO][NO3]3, stirred for 6 hours, dried in a drying oven for 12 hours, and finally calcinated at 550 °C for 6 hours.

[0112] Optionally, a substrate, such as SiC foam, can be coated with the powder catalysts using a wash coating method. Briefly, the SiC foam substrate is calcined and dried prior to wash coating. A solution is prepared comprising a binder and a powder catalyst. The solution includes a binder to powder catalyst weight ratio of 1 :1. The SiC foam is immersed in the solution, then removed from the solution, dried in an oven at 80 °C for an hour, and then calcined at 550 °C for six hours. Afterwards, additional coatings can be added following similarsteps of immersion, removal, drying, and calcining. In the final coating step, after the final immersion, the coated foam catalyst is dried at 80 °C overnight and then calcined in an oven at 550 °C for six hours.2. Ammonia Decomposition Over Powder Catalysts - Cs and K Promoters.

[0113] FIGS. 1A-1 B explore the effects of a Cs or a K promoter over Fe / CeO2powder catalyst for microwave-assisted ammonia decomposition. All powder catalysts (Cs-Ru / CeO2and Cs- Fe / CeO2) were prepared using the incipient wetness impregnation method, in line with Example 1 .

[0114] The reaction conditions were as follows. Catalytic activity for ammonia decomposition was conducted using SAIREM’s GMS1000 solid-state generator with an output power of 1 KW at 2.45 GHz. Each catalyst was loaded into a quartz tube with 8 mm-ID and 12 mm-OD and placed in the center of a mono-mode high-temperature microwave cavity. Tests were conducted at ambient pressure with temperatures ranging from 200 °C to 460 °C. Catalysts were tested in a flowing gas mixture of 2 vol. % NH3 balanced with nitrogen (98% N2). The feedstock flow rate was 100 mL / min for all of the tests conducted. The inlet gases NH3and N2were ultra-high purity grade (UHP, 99.999%) supplied by Airgas, Inc. The final product was analyzed using a four-channel Micro-GC (Inficon 3000). Catalyst loadings were as follows: Cs-Ru / CeO2(2-4%): 1 g; Cs-Fe / CeO2(5-10%): 1 g; and K-Fe / CeO2(5-10%): 1 g.

[0115] Results are shows in FIGS. 1A-1 B. Both Cs-Fe / CeO2and K-Fe / CeO2catalysts exhibited similar decomposition temperatures and hydrogen production rate. The Cs-Ru / CeO2catalyst decomposed at a slightly lower temperature while the hydrogen production rate is the same as the Fe-based catalysts. Cs and K promoters significantly lowered Fe / CeO2powder catalyst decomposition temperature.3. Ammonia Decomposition Over Coated SiC Foam - Boehmite Binder.

[0116] FIGS. 2A-2B, 3A-3B, 4A-4B, and 5A-5B explore a Cs-Ru / CeO2catalyst and a Cs- Fe / CeO2catalyst coated on SiC foam using boehmite as binder for microwave-assisted ammonia decomposition. Cs-Ru / CeO2(2-4 wt.%) and Cs-Fe / CeO2(5-10 wt.%) powder catalysts were prepared using the incipient wetness impregnation method. For this Example (and Example 4 and Example 5) SiC foam can be obtained, for example, as the SiC foam supplied by Lawrence Livermore National Laboratory. Wash coating was conducted using boehmite as a binder. Initially, SiC foam was calcined and dried before wash coating. A solution was prepared consisting of boehmite binder and a catalyst. SiC foam was immersed in the solution several times, dried, and then calcined. For Cs-Fe / CeO2, 5 wt.% of catalyst material and binder was coated on SiC foam. For Cs-Ru / CeC2, 1 wt.% of catalyst material andbinderwas coated on SiC foam. The wt. percentage of catalyst and binder coated on SiC foam was calculated based on SiC weight gain.

[0117] The reaction conditions were as follows. Catalytic activity for ammonia decomposition was conducted using SAIREM’s GMS1000 solid-state generator with an output power of 1 KW at 2.45 GHz. Each catalyst was loaded into a quartz tube with 8 mm-ID and 12 mm-OD and placed in the center of a mono-mode high-temperature microwave cavity. Tests were conducted at ambient pressure with temperatures ranging from 200 °C to 640 °C. Catalysts were tested in a flowing gas mixture of 2 vol. % NH3 balanced with nitrogen (98% N2). The feedstock flow rate was either 100 mL / min or 12.6 mL / min. The inlet gases NH3 and N2were ultra-high purity grade (UHP, 99.999%) supplied by Airgas, Inc. The final product was analyzed using a four-channel Micro-GC (Inficon 3000). The SiC catalyst-coated structures were as follows: Cs-Ru / CeO2coated on SiC foam using a boehmite binder (1 wt.% catalyst and binder) and Cs-Fe / CeO2coated on SiC foam using a boehmite binder (5 wt.% catalyst and binder). The wt. percentage of catalyst and binder coated on SiC foam was calculated based on SiC weight gain.

[0118] The catalytic activity for ammonia decomposition was also studied under thermal heating. For thermal heating, a traditional thermal fixed bed reactor was used. A similar method as that outlined for microwave heating was followed, with a catalyst being loaded into a quartz tube with 8 mm-ID and 12 mm-OD and placed in the thermal fixed bed reactor. Tests were conducted at ambient pressure with temperatures ranging from 200 °C to 450 °C. Catalysts were tested in a flowing gas mixture of 2 vol. % NH3 balanced with Nitrogen (98% N2). The feedstock flow rate was 100 mL / min. The inlet gases NH3 and N2 were ultra-high purity grade (UHP, 99.999%) supplied by Airgas, Inc. The final product was analyzed using a four-channel Micro-GC gas analyzer (Inficon 3000).

[0119] Results are shown in FIGS. 2A-2B, 3A-3B, 4A-4B, and 5A-5B. For FIGS. 5A-5B, a feedstock flow rate of 100 mL / min was used. Cs-Ru / CeO2catalyst coated on SiC foam using boehmite as binder showed superior hydrogen production and lower decomposition temperature as compared to the Cs-Fe / CeO2coated structure. A higher feedstock flow rate increased hydrogen production rate. Microwave and thermal fixed bed reactors exhibited similar ammonia decomposition temperature and hydrogen production rate. The main advantage of microwave reactors is rapid heating and cooling.4. Ammonia Decomposition Over Coated SiC Foam - Varied Binders.

[0120] FIGS. 6A-6B, 7A-7B, 8A-8B, 9A-9B, 10A-10B, 11A-11 B, and 12A-12B explore a Cs- Ru / CeO2catalyst coated on SiC foam using either boehmite or PVB as binder for microwave-assisted ammonia decomposition. Cs-Ru / CeO2(2-4 wt.%) powder catalysts were prepared using the incipient wetness impregnation method. Wash coating was conducted using either boehmite or PVB as a binder, in a manner similar to that outlined in Example 2.

[0121] The reaction conditions were as follows. Catalytic activity for ammonia decomposition was conducted using SAIREM’s GMS1000 solid-state generator with an output power of 1 KW at 2.45 GHz. Each catalyst was loaded into a quartz tube with 8 mm-ID and 12 mm-OD and placed in the center of a mono-mode high-temperature microwave cavity. Tests were conducted at ambient pressure with temperatures ranging from 200 °C to 500 °C. Catalysts were tested in a flowing gas mixture of 2 vol. % NH3 balanced with nitrogen (98% N2). The feedstock flow rate was either 100 mL / min or 12.6 mL / min. The inlet gases NH3 and N2were ultra-high purity grade (UHP, 99.999%) supplied by Airgas, Inc. The final product was analyzed using a four-channel Micro-GC (Inficon 3000). The catalysts and SiC loadings were as follows: Cs-Ru / CeO2(2-4%): 1 g; boehmite: 1 g; and Fe / CeO2(10 %): 1 g. The SiC catalyst- coated structures were as follows: Cs-Ru / CeO2coated on SiC foam using a boehmite binder (1 wt.% catalyst and binder) and Cs-Ru / CeO2coated on SiC foam using a PVB binder (6 wt.% catalyst and binder). The wt. percentage of catalyst and binder coated on SiC foam was calculated based on SiC weight gain.

[0122] Results are shown in FIGS. 6A-6B, 7A-7B, 8A-8B, 9A-9B, 10A-10B, 1 1A-1 1 B, and 12A-12B. For FIGS. 9A-9B, a feedstock flow rate of 100 mL / min was used. For FIGS. 12A- 12B, a feedstock flow rate of 100 mL / min was used. Blank boehmite is not active for NH3decomposition (see FIGS. 6A-6B and 7A-7B). Increasing the feedstock inlet flow rate enhances hydrogen production but has little effect on ammonia conversion (see FIGS. 8A- 8B). Fe / CeO2powder catalyst showed complete ammonia decomposition but requires a higher temperature to match Cs-Ru / CeO2powder catalyst hydrogen production (see FIGS. 9A-9B and 12A-12B). Both binders (PVB & boehmite) are effective with the highest activity observed in boehmite (see FIGS. 10A-10B and 1 1A-11 B). PVB binder exhibits low catalyst utilization compared to boehmite binder.5. Ammonia Decomposition Over Coated SiC Foam - PVB Binder.

[0123] FIGS. 15A-15B, 16, 17A-17B, 18, and 19 explore a Cs-Ru / CeO2catalyst coated on SiC foam using PVB as binder for microwave-assisted ammonia decomposition. Cs-Ru / CeO2(2-4 wt.%) powder catalyst was prepared using the incipient wetness impregnation method. Blank or non-coated SiC foam was dried and calcined before testing. Wash coating was conducted using PVB as a binder. Initially, SiC foam was calcined and dried before wash coating. A slurry solution was prepared consisting of PVB binder and a catalyst. SiC foam was immersed in the solution several times, dried, and then calcined. This wash-coated procedureis generally laid out in FIG. 13. FIG. 14A and FIG. 14B depict blank (non-coated) SiC and coated SiC, respectively. For Cs-Ru / CeO2, 6 wt.% of catalyst material and binder was coated on SiC foam. For Cs-Ru / CeO2, The wt. percentage of catalyst and binder coated on SiC foam was calculated based on SiC weight gain.

[0124] The reaction conditions were as follows. Catalytic activity for ammonia decomposition was conducted using SAIREM’s GMS1000 solid-state generator with an output power of 1 KW at 2.45 GHz. Each catalyst was loaded into a quartz tube with 8 mm-ID and 12 mm-OD and placed in the center of a mono-mode high-temperature microwave cavity. Tests were conducted at ambient pressure with temperatures ranging from 200 °C to 500 °C. Catalysts were tested in a flowing gas mixture of 2 vol. % NH3 balanced with nitrogen (98% N2). The feedstock flow rate was either 100 mL / min, 50 mL / min, or 12.6 mL / min. The inlet gases NH3 and N2were ultra-high purity grade (UHP, 99.999%) supplied by Airgas, Inc. The final product was analyzed using a four-channel Micro-GC (Inficon 3000). The catalysts and SiC loadings were as follows: Cs-Ru / CeO2: 1 g; SiC Blank: 1.87 g; and coated SiC Foam: 2.003 g.

[0125] Results are shown in FIGS. 15A-15B, 16, 17A-17B, 18, and 19. For FIGS. 17A-17B, 18, and 19, a feedstock flow rate of 100 mL / min was used. Wash-coated SiC foam showed complete ammonia decomposition, though it required a higher temperature compared to the powder catalyst to reach complete decomposition (see FIGS. 15A-15B and 17A-17B). It is possible that a relatively high flow rate (i.e., 100 mL / min) is responsible for or at least partially contributing to this observation. Increasing the feedstock inlet flow rate enhances hydrogen production. Blank or non-coated SiC showed no activity toward ammonia decomposition. Results for Raman spectroscopy are shown in FIG. 16. The spectra indicated that Cs-Ru / CeO2catalyst is coated on the coated SiC foam.

[0126] It should be emphasized that the above-described embodiments of the present disclosure are merely possible examples of implementations set forth for a clear understanding of the principles of the disclosure. Many variations and modifications may be made to the above-described embodiment(s) without departing substantially from the spirit and principles of the disclosure. All such modifications and variations are intended to be included herein within the scope of this disclosure and protected by the following claims.

Claims

CLAIMSWhat is claimed is:

1. A method comprising: flowing a gas mixture over a catalyst in a reaction chamber; and heating the gas mixture and the catalyst, thereby producing a gaseous product; wherein the gas mixture comprises ammonia; and wherein the catalyst comprises a first metallic particle and a second metallic particle dispersed on a support; wherein the support is selected from CeOx, carbon, carbon nanotube, SiC, AI2O3, TiC>2, aluminosilicate, and MXene; wherein the first metallic particle is selected from Ru, Co, Fe, and Ni; and wherein the second metallic particle is selected from Cs and K.

2. The method of claim 1 , wherein the gas mixture has a flow rate of from about 10 mL / min to about 1000 mL / min per one milliliter of the catalyst.

3. The method of claim 1 , wherein the gas mixture and the catalyst are heated to a temperature ranging from about 100 °C to about 600 °C.

4. The method of claim 1 , wherein the gas mixture and the catalyst are heated to a temperature ranging from about 250 °C to about 500 °C.

5. The method of claim 1 , wherein the gas mixture and the catalyst are heated using microwave irradiation.

6. The method of claim 1 , wherein the gas mixture and the catalyst are heated using thermal heating.

7. The method of claim 1 , wherein the method is carried out at a pressure of about 0.5 atm to about 45 atm.

8. The method of claim 1 , wherein the method is carried out at a pressure of about 1 atm to about 10 atm.

9. The method of claim 1 , wherein the first metallic particle is selected from Ru and Fe.

10. The method of claim 1 , wherein the support is selected from CeO2, carbon nanotube, SiC, AI2O3, TiC>2, and a zeolite.

11. The method of claim 10, wherein the support is a zeolite selected from a pentasil zeolite and a faujasite-type structure zeolite.

12. The method of claim 1 , wherein the catalyst comprises from about 1 wt.% to about 15 wt.% the first metallic particle and the second metallic particle.

13. The method of claim 1 , wherein the catalyst comprises from about 1 wt.% to about 10 wt.% the first metallic particle and the second metallic particle.

14. The method of claim 1 , wherein the catalyst further comprises a structured support and a binder.

15. The method of claim 14, wherein the structured support is a monolithic support or a foam.

16. The method of claim 14, wherein the structured support comprises SiC.

17. The method of claim 14, wherein the binder comprises boehmite, polyvinyl butyral, aluminum hydroxide, silicate hydrate, or a combination thereof.

18. The method of claim 14, wherein the catalyst comprises from about 1 wt.% to about 10 wt.% of the first metallic particle, the second metallic particle, the support, and the binder.

19. The method of claim 14, wherein the catalyst comprises from about 1 wt.% to about 5 wt.% of the first metallic particle, the second metallic particle, the support, and the binder.

20. The method of claim 14, wherein the catalyst comprises from about 90 wt.% to about 99 wt.% of the structured support.

21. The method of claim 14, wherein the catalyst comprises from about 95 wt.% to about 99 wt.% of the structured support.

22. The method of claim 1 , wherein the gaseous product comprises hydrogen and nitrogen.

23. The method of claim 1 , wherein the method results in about 50% to 100% conversion of ammonia in the gas mixture to hydrogen and nitrogen.

24. The method of claim 1 , wherein the method results in about a 90% to about 100% conversion of ammonia in the gas mixture to hydrogen and nitrogen.

25. A composition, comprising hydrogen produced using the method of claim 1.

26. A catalyst, comprising: a structured support; a binder dispersed on the structured support; and a particulate catalyst dispersed on the structured support, wherein the particulate catalyst comprises: a support selected from CeOx, carbon, carbon nanotube, SiC, AI2O3, TiCh, aluminosilicate, and MXene; a first metallic particle dispersed on the support, wherein the first metallic particle is selected from Ru, Co, Fe, and Ni; and a second metallic particle dispersed on the support, wherein the second metallic particle is selected from Cs and K.

27. The catalyst of claim 26, wherein the structured support is a monolithic support or a structured foam.

28. The catalyst of claim 26, wherein the structured support comprises SiC.

29. The catalyst of claim 26, wherein the first metallic particle is selected from Ru and Fe.

30. The catalyst of claim 26, wherein the support is selected from CeC>2, carbon nanotube, SiC, AI2O3, TiC>2, and a zeolite.

31. The catalyst of claim 30, wherein the support is a zeolite selected from a pentasil zeolite and a faujasite-type structure zeolite.

32. The catalyst of claim 26, wherein the particulate catalyst comprises from about 1 wt.% to about 15 wt.% the first metallic particle and the second metallic particle.

33. The catalyst of claim 26, wherein the particulate catalyst comprises from about 1 wt.% to about 10 wt.% the first metallic particle and the second metallic particle.

34. The catalyst of claim 26, wherein the binder comprises boehmite, polyvinyl butyral, aluminum hydroxide, silicate hydrate, or a combination thereof.

35. The catalyst of claim 26, wherein the catalyst comprises from about 1 wt.% to about 10 wt.% of the particulate catalyst and the binder.

36. The catalyst of claim 26, wherein the catalyst comprises from about 1 wt.% to about 5 wt.% of the particulate catalyst and the binder.

37. The catalyst of claim 26, wherein the catalyst comprises from about 90 wt.% to about 99 wt.% of the structured support.

38. The catalyst of claim 26, wherein the catalyst comprises from about 95 wt.% to about 99 wt.% of the structured support.

Images