Preparation of nanosheet zeolites and applications for methane dehydroaromatization

Abstract

Methods for making a Mo-nanosheet-CHA catalyst and Mo-meso-CHA catalyst. The method includes preparing an aqueous solution comprising one or more structure directing agents, mixing the aqueous solution with at least one silicon precursor and at least one aluminum precursor to provide a synthesis gel; recovering crystalline solids from the synthesis gel, wherein the crystalline solids consist of CHA zeolite crystallites; depositing a source of molybdenum onto the CHA zeolite crystallites to provide Mo-CHA zeolite crystallites having an average particle size of less than 200 nm in Mo-nanosheet-CHA and an average particle size > 500 nm in Mo-meso-CHA and containing a plurality of CHA zeolite pores; and carburizing the Mo-CHA zeolite crystallites at a temperature of 500°C to 900°C and a pressure of 80-100 kPa in the presence of methane (CHa) to form Mo carbide domains within the CHA zeolite pores. The Mo-nanosheet-CHA and Mo-meso-CHA catalysts are particularly useful for converting methane to aromatics.

Description

PREPARATION OF NANOSHEET ZEOLITES AND APPLICATIONS FOR METHANE DEHYDROAROMATIZATIONGOVERNMENT LICENSE RIGHTS

[0001] This invention was made with government support under Cooperative Agreement No. EEC-1647722 awarded by the National Science Foundation. The government has certain rights in the invention.BACKGROUNDField of the Invention

[0002] Embodiments provided herein related to nanosheet zeolites, nanosheet zeotypes and methods for making same. Embodiments provided herein further relate to methane dehydroaromatization processes that use the nanosheet zeolites and zeotypes described herein.Description of the Related Art

[0003] Methane dehydroaromatization (DHA) is a promising pathway to convert methane into higher liquid density chemicals such as aromatics (e.g., benzene) while co-producing hydrogen gas (H2). This reaction is endothermic and constrained by thermodynamics, so it requires high temperatures (>873 K) to obtain CH4 conversions of >5%. A typical catalyst used for this reaction is molybdenum supported on an aluminosilicate zeolite, of which the MFI framework structure is most commonly used. Mo-MFI zeolites used in methane DHA can provide near-equilibrium conversion (-10% at 973 K) with high aromatics selectivity (-80%).

[0004] Zeolites are microporous aluminosilicate materials that contain tetrahedral silicon atoms linked by oxygen, forming charge-neutral crystalline structures. The isomorphous substitution of trivalent aluminum atoms for tetravalent silicon introduces a negative charge imbalance that can be compensated by protons or metal cations or complexes, all of which can serve as active sites for catalysis. Zeotypes are a related class of microporous materials, but zeotypes can include elements in addition to just Si, Al, O and H. Typical methods to synthesize Mo-MFI catalysts involve the deposition of MoOr onto MFI zeolites either through incipient wet impregnation (IWI) or by creating a physical mixture of the two solids. This MoOs-MFI composite material is then typically heated under flowing air at high temperatures (>773 K) to transform MoO3 domains into ion-exchanged Mo species located on or within the MFI zeolite crystallites, which are referred to as the active site precursors. These ion-exchanged Mo speciescarburize under reaction conditions (i.e., 950 K, 90 kPa CH4) to form Mo carbide domains, which catalyze the methane DHA reaction.

[0005] One of the main challenges to developing a catalytic process for methane DHA using Mo-MFI is the relatively fast catalyst deactivation (~10 hr), which over time leads to an irreversible loss in activity. This deactivation can be overcome, in part, by developing a continuous process of reaction and regeneration cycles in which the catalyst is continuously recirculated between the reactor unit where it reacts with methane and deactivates and a separate regeneration unit. To realize this process, however, the catalyst must sustain large numbers of reaction-regeneration cycles. Reaction and regeneration cycles (using air or O2) have been performed with Mo-MFI catalysts but it has been observed that the aromatics yield decreases systematically with increasing numbers of these cycles. This is caused by MFI zeolite framework dealumination during the regeneration cycles. As more framework Al atoms are removed from the zeolite support (i.e. dealumination), fewer ion-exchanged Mo species form during the regeneration step, and thus fewer active Mo-carbide domains form during the reaction step to catalyze methane DHA.

[0006] CHA is a high symmetry (only one distinct tetrahedral-site), three-dimensional pore connectivity framework consisting of double six-membered (6-MR) ring building units that interconnect to form 8-MR windows (-0.38 nm in diameter) and larger CHA cages. Cu- exchanged on aluminosilicate CHA zeolites (e.g., Cu-SSZ-13) have shown an improved high- temperature (>773 K) hydrothermal stability over Cu-MFI catalysts. Micropore volumes measured before and after exposure of Cu-CHA to water at 1073 K have shown that the pore structure of CHA did not change significantly, while Cu-MFI exposed to the same conditions led to a -60% decrease in micropore volume.

[0007] Kosinov et al. conducted DHA reactions using 5 wt% Mo supported on CHA (SSZ- 13) and observed a ~4x smaller cumulative amount of methane converted (over 16 hr of reaction) and negligible amounts of benzene formed relative to Mo-MFI. This was attributed to the larger effective diameter of benzene (-0.56 nm) compared to the smaller size of CHA 8- MR micropores (-0.38 nm diameter), which prevents the diffusion of aromatic products formed within the catalyst micropores to the external fluid phase.

[0008] Agote-Aran et al. used X-ray absorption spectroscopy (XAS) to report that Mo active site precursors in CHA zeolite are similar to the Mo species formed in MFI zeolite. They also used backscattering-SEM imaging to observe the dispersion of Mo after high temperature air treatments and correlated the lower Mo dispersion on Mo-CHA (4 wt% Mo) to the near- negligible production of benzene during DHA reactions. Mo-CHA catalysts have not beenwidely studied compared to Mo-MFI due to the low conversions and benzene selectivities reported.BRIEF DESCRIPTION OF THE DRAWINGS

[0009] So that the manner in which the above recited features of the present invention can be understood in detail, a more particular description of the invention, briefly summarized above, may be had by reference to embodiments, some of which are illustrated in the appended drawings. It is to be noted, however, that the appended drawings illustrate only typical embodiments of this invention and are, therefore, not to be considered limiting of its scope, for the invention may admit to other equally effective embodiments. It is emphasized that the figures are not necessarily to scale and certain features and certain views of the figures can be shown exaggerated in scale or in schematic for clarity and / or conciseness.

[0010] FIG. 1 depicts a H2 temperature programmed reduction (TPR) profile of Mo-CHA after air treatment at 823 K for 6 hr.

[0011] FIG. 2 depicts a H2 temperature programmed reduction (TPR) profile of Mo-MFI after air treatment at 823 K for 6 hr.

[0012] FIG. 3 shows methane conversion (♦) and carbon yield (0) for a single methane DHA run on Mo-MFI. Reaction conditions: 950 K, 60 / 40 (vol / vol) CH Ar, 115 kPa total pressure, 11.8 (mol Mo) s (mol CH4)1contact time.

[0013] FIG. 4A shows forward rates of benzene formation measured on Mo-CHA, Mo- nano-CHA, Mo-nanosheet-CHA, and Mo-meso-CHA catalysts, normalized by the initial forward rate of benzene formation measured on Mo-MFI.

[0014] FIG. 4B shows the benzene selectivity (defined as moles of carbon in benzene formed divided by moles of carbon in methane converted) on Mo-CHA (reference data in Agote-Aran et al., Molecules, 25, 2020, 5048), Mo-CHA, Mo-nano-CHA, Mo-nanosheet- CHA, and Mo-meso-CHA catalysts.

[0015] FIG. 5 shows the initial forward rate of benzene formation measured after a given number of reaction-regeneration cycles on Mo-MFI, normalized by the initial forward rate of benzene formation measured in the 1streaction-regeneration cycle. Reaction conditions: 950 K, 60 / 40 (vol / vol) CH Ar, 115 kPa total pressure, 17.5 (mol Mo) s (mol CH4)1contact time. Regeneration conditions: 823 K, air, 6 hr. Argon flush in between reaction-regeneration steps.

[0016] FIG. 6 shows the initial forward rate of benzene formation measured after a given number of reaction-regeneration cycles on Mo-nanosheet-CHA, normalized by initial forward rate of benzene formation measured in the 1streaction -regeneration cycle. Reaction conditions:950 K, 60 / 40 (vol / vol) CI E / Ar, 115 kPa total pressure, 12 (mol Mo)' s- (mol CH4)1contact time. Regeneration conditions: 823 K, air, 6 hr. Argon flush in between reaction-regeneration steps.

[0017] FIG. 7 shows the initial forward rate of benzene formation measured after a given number of reaction-regeneration cycles on Mo-meso-CHA, normalized by initial forward rate of benzene formation measured in the 1streaction-regeneration cycle. Reaction conditions: 950 K, 90 / 10 (vol / vol) CFU / Ar, 110 kPa total pressure, 10 (mol Mo) s (mol CH4)1contact time. Regeneration conditions: 823 K, air, 6 hr. Argon flush in between reaction-regeneration steps.SUMMARY OF THE INVENTION

[0018] Methods for making nanosheet zeolite, mesoporous zeolite and / or zeotypes catalysts are provided. Molybdenum (Mo) can be supported on the nanosheet zeolite, mesoporous zeolite and / or zeotypes. The nanosheet zeolite, mesoporous zeolite and / or zeotype can have the CHA framework, although it is believed that other zeolite frameworks, such as the AEI, RTH, and LTA frameworks, can be used. The method includes preparing an aqueous solution comprising one or more structure directing agents, mixing the aqueous solution with at least one silicon precursor and at least one aluminum precursor to provide a synthesis gel; recovering crystalline solids from the synthesis gel, wherein the crystalline solids consist of CHA zeolite crystallites; depositing a source of molybdenum onto the CHA zeolite crystallites to provide Mo-CHA zeolite crystallites having an average particle size of less than 200 nm in Mo-nanosheet-CHA and an average particle size > 500 nm in Mo-meso-CHA; and carburizing the Mo-CHA zeolite crystallites at a temperature of 500°C to 900°C and a pressure of 80-100 kPa in the presence of methane (CH4) to form Mo carbide domains within the CHA zeolite pores.

[0019] The Mo nanosheet zeolite, mesoporous zeolite and / or zeotypes are particularly useful for MTO and DHA catalysts.DETAILED DESCRIPTION

[0020] Embodiments provided herein generally relate to the synthesis of metals supported on nanosheet zeolites, mesoporous zeolite and / or zeotypes, which have a plate-shaped crystallite morphology. Embodiments provided herein specifically relate to the synthesis of Mo supported on CHA type zeolites with a plate-shaped crystallite morphology (hereafter referred to as nanosheet-CHA) or Mo supported on CHA type zeolites with mesoporosity (hereafter referred to as meso-CHA) and its application for methane DHA reaction-regeneration cycles.It has been surprisingly discovered that Mo supported on nanosheet-CHA zeolites lead to a significant increase in both measured DHA rates (per Mo) and benzene selectivities, compared to Mo supported on CHA zeolites with larger crystallite sizes (> 1 pm). It has also been surprisingly discovered that the measured DHA rates (per Mo) remain unchanged after several (>10) cycles of reaction-regeneration, in contrast to Mo-MFI zeolites that show irreversible deactivation when subjected to an equal number of reaction-regeneration cycles at similar regeneration conditions. It has also been surprisingly discovered that the Mo-nanosheet-CHA is more structurally robust and can be regenerated to recover initial catalytic performance over a larger number of reaction-regeneration cycles. It has also been surprisingly discovered that the measured DHA rates (per Mo) are higher on Mo-meso-CHA compared to Mo supported on CHA zeolites with similar crystallite size (> 1 pm) but without mesopores.

[0021] It is to be understood that the following disclosure describes several exemplary embodiments for implementing different features, structures, or functions of the invention. Exemplary embodiments of components, arrangements, and configurations are described below to simplify the present disclosure; however, these exemplary embodiments are provided merely as examples and are not intended to limit the scope of the invention. Additionally, the present disclosure can repeat reference numerals and / or letters in the various embodiments and across the figures provided herein. This repetition is for the purpose of simplicity and clarity and does not in itself dictate a relationship between the various embodiments and / or configurations. Moreover, the exemplary embodiments presented below can be combined in any combination of ways, i.e., any element from one exemplary embodiment can be used in any other exemplary embodiment, without departing from the scope of the disclosure.

[0022] Additionally, certain terms are used throughout the following description and claims to refer to particular components. As one skilled in the art will appreciate, various entities can refer to the same component by different names, and as such, the naming convention for the elements described herein is not intended to limit the scope of the invention, unless otherwise specifically defined herein. Further, the naming convention used herein is not intended to distinguish between components that differ in name but not function.

[0023] Furthermore, in the following discussion and in the claims, the terms “including” and “comprising” are used in an open-ended fashion, and thus should be interpreted to mean “including, but not limited to.” The phrase “consisting essentially of’ means that the described / claimed composition does not include any other components that will materially alter its properties by any more than 5% of that property, and in any case does not include any other component to a level greater than 3 mass%.

[0024] Unless otherwise indicated, all numerical values are "about" or "approximately" the indicated value, meaning the values take into account experimental error, machine tolerances and other variations that would be expected by a person having ordinary skill in the art. It should also be understood that the precise numerical values used in the specification and claims constitute specific embodiments. Efforts have been made to ensure the accuracy of the data in the examples. However, it should be understood that any measured data inherently contains a certain level of error due to the limitation of the technique and / or equipment used for making the measurement.

[0025] In the following discussion and in the claims, the terms “including” and “comprising” are used in an open-ended fashion, and thus should be interpreted to mean “including, but not limited to.” The phrase “consisting essentially of’ means that the described / claimed composition does not include any other components that will materially alter its properties by any more than 5% of that property, and in any case, does not include any other component to a level greater than 3 wt%.

[0026] The term “or” is intended to encompass both exclusive and inclusive cases, i.e., “A or B” is intended to be synonymous with “at least one of A and B ,” unless otherwise expressly specified herein.

[0027] The indefinite articles “a” and “an” refer to both singular forms (i.e., “one”) and plural referents (i.e., one or more) unless the context clearly dictates otherwise. For example, embodiments using “an olefin” include embodiments where one, two, or more olefins are used, unless specified to the contrary or the context clearly indicates that only one olefin is used.

[0028] The term “wt%” means percentage by weight, “vol%” means percentage by volume, “mol%” means percentage by mole, “ppm” means parts per million, and “ppm wt” and “ppmw” are used interchangeably and mean parts per million on a weight basis. All concentrations herein, unless otherwise stated, are expressed on the basis of the total amount of the composition in question.

[0029] Each of the appended claims defines a separate invention, which for infringement purposes is recognized as including equivalents to the various elements or limitations specified in the claims. Depending on the context, all references to the “invention” may in some cases refer to certain specific embodiments only. In other cases, it will be recognized that references to the “invention” will refer to subject matter recited in one or more, but not necessarily all, of the claims. Each of the inventions will now be described in greater detail below, including specific embodiments, versions and examples, but the inventions are not limited to these embodiments, versions or examples, which are included to enable a person having ordinaryskill in the art to make and use the inventions, when the information in this disclosure is combined with publicly available information and technology.

[0030] As used herein, the terms “crystallite” and “crystal” are used interchangeably and meant to refer to the same.

[0031] As used herein, the term “meso-CHA” refers to CHA type zeolite and / or zeotype samples made with a dimethyloctadecyl[3-(trimethoxysilyl)propyl]ammonium chloride (“TPOAC”) growth modifier and have crystallite sizes of 1-2 pm. The term “meso-CHA” also refers to crystallites that are microporous, meaning the crystallites have average pore openings less than 2 nanometers in diameter, and more specifically average pore openings that are about 0.4 nanometers in diameter as determined by the CHA crystal framework. The meso-CHA crystallites also have mesoporosity, meaning they have pores that are larger than 2 nanometers in diameter, such as 2-1,000 nm, 5-500 nm, or 100- 1,000 nm. According to one or more embodiments, the average particle size of the meso-CHA crystallites can be greater than 500 nm or greater than 1 ,000 nm. The average particle size of the meso-CHA crystallites also can range from 0.5-2 pm.

[0032] As used herein, the term “nano-CHA” refers to CHA type zeolite and / or zeotype samples made with polyethylenime (“PEIM”) growth modifier and have crystallite sizes between than 100-500 nm. The term “nano-CHA” also refers to crystallites that are microporous, meaning the crystallites have average pore openings less than 2 nanometers in diameter, and more specifically average pore openings that are about 0.4 nanometers in diameter as determined by the CHA crystal framework. According to one or more embodiments, the average particle size of the nano-CHA crystallites is 180 nm (such as between 100-500 nm).

[0033] As used herein, the term “nanosheet-CHA” refers to CHA type zeolite and / or zeotype samples made with a dimethyloctadecyl[3-(trimethoxysilyl)propyl]ammonium chloride (“TPOAC”) growth modifier and have crystallite sizes of less than 200 nm, such as 2- 100 nm; 5 to 85 nm; 10-70 nm; 15- 60 nm and / or 20-50 nm. The term “nanosheet-CHA” also refers to crystallites that are microporous, meaning the crystallites have average pore openings less than 2 nanometers in diameter, and more specifically average pore openings that are about 0.4 nanometers in diameter as determined by the CHA crystal framework. The nanosheet-CHA crystallites also have minimal mesoporosity, meaning they have a minimum percentage (such as less than 1%) of pores that are larger than 2 nanometers in diameter; therefore, they are morphologically distinct from hierarchical CHA zeolites prepared using other multi-stepmethods. According to one or more embodiments, the average particle size of the nanosheet- CHA crystallites are less than 200 nm (such as between 1-200 nm). The average particle size of the nanosheet-CHA crystallites also can range from 1 nm to 200 nm; 2 nm to 200 nm; or 3 to 190 nm. The average particle size of the nanosheet-CHA crystallites can also range from a low of about 1, 2, 3, or 5 nm to a high of about 50, 100, 150 or 199 nm.

[0034] The present disclosure is not limited by any particular method for making the nanosheet-CHA or meso-CHA catalyst described herein. In general, any method can be used that provides compositions of matter containing the prescribed components in effective amounts.

[0035] In at least one embodiment, a Mo impregnated nanosheet- CHA crystallite is provided. The Mo impregnated nanosheet- CHA crystallite can be prepared using any suitable technique. For example, co-precipitation from an aqueous, an organic, or a combination solution-dispersion, impregnation, dry mixing, wet mixing or the like, can be used alone or in various combinations. According to one embodiment, incipient wetness impregnation can be used although other impregnation techniques like soaking, pore volume impregnation, or percolation can be employed. Alternate methods such as ion exchange, wash coat, precipitation, and gel formation can also be used.

[0036] In at least one embodiment, a Mo impregnated meso- CHA crystallite is provided. The Mo impregnated meso- CHA crystallite can be prepared using any suitable technique. For example, co-precipitation from an aqueous, an organic, or a combination solution-dispersion, impregnation, dry mixing, wet mixing or the like, can be used alone or in various combinations. According to one embodiment, incipient wetness impregnation can be used although other impregnation techniques like soaking, pore volume impregnation, or percolation can be employed. Alternate methods such as ion exchange, wash coat, precipitation, and gel formation can also be used.

[0037] The Mo nanosheet- CHA catalyst and / or Mo meso- CHA catalysts described herein can be synthesized by modifying a typical hydrothermal synthesis procedure, such as that described in Di Iorio, J. and Gounder, R. et al. Chem. Mater. 28 (2016) 2236-2247. For example, an aqueous solution containing organic and / or inorganic structure directing agents (SDAs) is first prepared to provide a “precursor solution”. Any suitable SDA can be used. Suitable SDAs can include molecules providing N,N,N-trimethyl-l-adamantylammonium (TMAda+) and / or sodium (Na+) cations. Then, this precursor solution is mixed with dimethyloctadecyl[3-(trimethoxysilyl)propyl]ammonium chloride (TPOAC), at least one aluminum precursor and at least one silicon precursor, to prepare a final synthesis gel that isthen subjected to a crystallization procedure to prepare the nanosheet-CHA material. Crystalline solids are recovered, then treated in air at high temperatures to remove any unreacted organic SDAs, and then subjected to an ion-exchange (commonly with NHC) to remove any unreacted inorganic SDAs. Next, MoO3 is deposited onto the CHA zeolite crystallites either through incipient wet impregnation (IWI) or by creating a physical mixture of the two solids, and heated under flowing air at high temperatures (>773 K) to transform MoOr domains into ion-exchanged Mo species that are located on or within the CHA zeolite crystallites, which are referred to as the active site precursors. Finally, these ion-exchanged Mo species carburize under reaction conditions (e.g., 950 K, 90 kPa CH4) to form Mo carbide domains, which can be used to catalyze the methane DHA reaction.

[0038] The source of aluminum can be aluminum hydroxide, aluminum nitrate, aluminosilicate, and any combinations or derivatives thereof. The source of silicon can be colloidal silica, a silicon alkoxide compound, fumed silica, amorphous silica, aluminosilicate, and any combinations or derivatives thereof. The Si: Al ratio can range from a low of about 10, 20, 30 or 40 to high of about 50, 80, 100, or 200.

[0039] The crystallization process preferably occurs at about 130°C to about 150°C, but can range from as low of about 60°C, 70°C, 80°C or 90°C to a high of about 150°C, 180°C, 200°C or 240°C. The crystallization process can also take place at about 100°C, 130°C, 140°C, 150°C, 160°C, 170°C, or 180°C.

[0040] The high temperature air calcination treatment can occur at about 450°C to about 550°C. The air calcination treatment can also range from as low of about 400°C, 410°C, or 420°C to a high of about 500°C, 550°C or 600°C.

[0041] In certain embodiments, the dehydroaromatization can be performed in any suitable reactor, such as a fixed bed gas-phase reactor. A dual bed circulating fluidized bed reactor system can be used to allow for continuous regeneration of deactivated catalyst using hot air or H2. The feed for the dehydroaromatization reactor can include argon gas (generally ranging between 0-99 vol%, but typically ranging between 5-60 vol%, when used) in addition to methane. The dehydroaromatization reaction can be performed at 600 to 900°C in the presence of the nanosheet CHA catalyst described herein. The dehydroaromatization reaction typically includes a mixture of methane and argon in a 2:1 volume ratio at a GHSV of from 100-100,000 ml / hr g-cat, a total pressure of 1 atm (but generally ranging between 0.1-100 atm) and a reaction temperature of 750°C (but ranging between 600-900°C, more preferably between 700- 800 °C) in the presence of the catalyst for about 1 hour. The GHSV also can range from a low of about of about 100, 1,500, or 3,500 ml / hr g-cat to a high of about 7,000, 20,000, or 90,000ml / hr g-cat. The GHSV also can be about 4,000 ml / hr g-cat, 4,500 ml / hr g-cat, 5,000 ml / hr g- cat. or 5,200 ml / hr g-cat.

[0042] The methane can be derived from any hydrocarbon stream, such as natural gas or shale gas. The methane also can be any hydrocarbon stream. The term “hydrocarbon stream” refers to any stream that naturally contains methane and one or more other hydrocarbons. Illustrative hydrocarbon streams can be or can include a raw shale gas stream or raw natural gas stream or other raw hydrocarbon gaseous stream that is obtained directly (j.e. without processing to remove water and / or acid gas) from a reservoir, wellhead, or pipeline. Suitable hydrocarbon streams can also originate from a refinery, such as from a FCC, coker, steam cracker, and pyrolysis gasoline (pygas). Suitable hydrocarbon streams can also be or can include coal gas. Illustrative hydrocarbon streams can also be or can also include a gas stream that has been treated for acid gas and water removal.

[0043] The term “liquid hydrocarbon” refers to a hydrocarbon that is liquid at room temperature and ambient pressure, and primarily includes Cs+ hydrocarbons. Moreover, this term can also refer to hydrocarbons that are liquid at room temperature but require high pressure such C4 alkane and alkenes.

[0044] The term “shale gas” refers to natural gas that is produced from a shale or other tight formation, is a gaseous phase mixture containing natural gas liquids, acid gases, water, nitrogen (N2), and possibly trace amounts of contaminants. A suitable shale gas (or natural gas) contains at least 50 mol% CH4 and up to 50 mol% of C2H6, C3H8, C4H10, and / or C5+ hydrocarbons. For example, a suitable shale gas (or natural gas) contains about 60 mol% to about 95 mol% CH4 and about 5 mol% to about 45 mol% of C2H6, C3H8, C4H10, and / or C5+ hydrocarbons (or collectively referred to as “C2+ hydrocarbons” or “C2+ alkanes”). Among the C2+ hydrocarbons, C2H6 is generally the highest concentration followed by C3H8 then C4H10. Nitrogen gas (N2) can also be present in the shale gas.

[0045] The resulting aromatic products can be selected from the group consisting of benzene, toluene, xylene, naphthalene, and coke. An illustrative aromatic product slate can include benzene (50-60 mol%), toluene (0-5 mol%), xylene (0-1 mol%), naphthalene (10-20 mol%), and coke (10-50 mol%), for example. The aromatic product also can contain benzene in amounts that range from about 50-60 mol%; about 55-65 mor%, or about 50-70 mol%.EXAMPLES

[0046] Embodiments discussed and described herein can be further described with the following examples. Although the following examples are directed to specific embodiments, they are not to be viewed as limiting in any specific respect.Comp. Ex. 1 : H-MFI

[0047] Commercial NHC-MFI (Si / Al = 13) was obtained from Zeolyst International (CBV 2314) and converted into H-MFI by flowing dry air ( 1.67 cm3s’1g1, Air Zero, Indiana Oxygen) in a muffle furnace at 773 K for 4 hr (0.0167 K s’1).Comp. Ex. 2: Mo-MFI

[0048] Another comparative catalyst of Mo-MFI (Mo / Al = 0.25) was prepared by incipient wet impregnation (IWI). To form the Mo-MFI, an aqueous solution was prepared by adding (NH4)6Mo?O24 (Fischer Scientific, 99.9%) salt to deionized water. Around 0.37 grams of the (NH4)6MO?O24 salt was mixed with 4.65 grams of deionized water to create an aqueous molybdenum solution with a concentration of 0.078 grams of salt per gram of water (about 1 wt% Mo). Then, about 0.60 grams of this solution was added to about 1.10 grams of H-MFI in a dropwise manner while stirring. The sample was then treated in flowing dry air (1.67 cm3s’1g’1, Air Zero, Indiana Oxygen) in a muffle furnace at 823 K for 6 hr (0.0167 K s’1).Example 1 : Nanosheet-CHA

[0049] Nanosheet-CHA was prepared by mixing 6.42 g of TMAdaOH and 3.05 g of NaOH (10 wt% made from NaOH (98 wt%, Alfa Aesar) pellets) and 14.02 g of deionized water (18.2 Mil) for 0.25 hr in a PFA container with a Teflon stir bar at ambient temperature to prepare an aqueous precursor solution. Around 1.49 g of dimethyloctadecyl[3- (trimethoxysilyl)propyl]ammonium chloride (TPOAC, 42 wt% in methanol, Sigma-Aldrich) was then added to the aqueous precursor solution. Around 0.16 g of aluminum hydroxide (Al(0H)3, 98 wt%, SPI Pharma) was then added and mixed for 0.25-0.5 hr until solids were completely dissolved. Finally, 4.41 g of the silica source (Ludox HS-40, 40 wt%, Sigma- Aldrich) was added to the solution and homogenized for 2-4 hr. The molar composition of the final synthesis gel for nanosheet-CHA was 0.033 AI2O3 / O.96 SiO2 / 0.04 TPOAC / O.25 NaOH / O.25 TMAdaOH / 44 H2O.Example 2: Meso-CHA

[0050] Meso-CHA was prepared by mixing 6.42 g of TMAdaOH and 3.05 g of NaOH (10 wt% made from NaOH (98 wt%, Alfa Aesar) pellets) and 16.6025 g of deionized water (18.2 MQ) for 0.25 hr in a PFA container with a Teflon stir bar at ambient temperature to prepare an aqueous precursor solution. Around 1.45 g of dimethyloctadecyl[3- (trimethoxysilyl)propyl]ammonium chloride (TPOAC, 42 wt% in methanol, Sigma-Aldrich) was then added to the aqueous precursor solution. Around 0.12 g of aluminum hydroxide (A1(OH)3, 98 wt%, SPI Pharma) was then added and mixed for 0.25-0.5 hr until solids were completely dissolved. Finally, 1.76 g of the silica source (Fumed Silica, Cab-O-Sil, Sigma-Aldrich) was added to the solution and homogenized for 2-4 hr. The molar composition of the final synthesis gel for meso-CHA was 0.033 AI2O3 / O.96 SiCh / O.O TPOAC / 0.25 NaOH / O.25 TMAdaOH / 44 H2O.Example 3: Nano-CHA

[0051] Nano-CHA was synthesized according to the disclosure of Kumar, M., et al. J. Am. Chem. Soc. 137 (2015) 13007-13017. Starting with the precursor solution, polyethylenime (PEIM, 50 wt% in water, Sigma-Aldrich) was added to form 1.6 wt% PEIM solution gel. Then, aluminum hydroxide (A1(OH)3, 98 wt%, SPI Pharma) was added to the solution and mixed for 0.25-0.5 hr until solids were completely dissolved. Finally, the silica source (Ludox HS-40, 40 wt%, Sigma- Aldrich) was added to the solution and homogenized for 2-4 hr. The molar composition of the final synthesis gel for nano-CHA was 1 SiO2 / 0.033 AI2O3 / O.3 TMAdaOH / 0.2 NaOH / 44 H2O.Example 4: CHA

[0052] CHA was synthesized according to the disclosure of Di Iorio, J. and Gounder, R. et al. Chem. Mater. 28 (2016) 2236-2247. Starting with the precursor solution, aluminum isopropoxide (Al(i-pro)3, 98 wt%, Sigma- Aldrich) was added and mixed for 0.25-0.5 hr until solids were completely dissolved. Finally, the silica source (Ludox HS-40, 40 wt%, Sigma- Aldrich) was added to the solution and homogenized for 2-4 hr. The molar composition of the final synthesis gel for the reference CHA was 0.033 AI2O3 / I SiO2 / 0.25 NaOH / O.25 TMAdaOH / 44 H2O.

[0053] For all foregoing syntheses, solids were recovered using crystallization and washed with deionized water until a neutral pH was obtained. Solids were dried in a static oven at 373 K overnight and then treated in dry flowing air (1.67 cm3s'1g1, Air Zero, Indiana Oxygen) at 853 K (0.0167 K s1) to remove occluded organic structure directing agents. NHC-CHA was prepared by contacting Al-CHA with a 1.0 M NH4NO3 solution (150 g solution (g solid)1) in PFA containers with Teflon magnetic bars for 24 hr at ambient temperature. Solids were recovered via centrifugation using 4-5 cycles of deionized water (18.2 MQ) until supernatant had a neutral pH and dried overnight in a static oven at 373 K.Example 5: Mo-CHA synthesis

[0054] Mo-CHA (Mo / Al = 0.19) was prepared by incipient wet impregnation (IWI). First, an aqueous solution was prepared by adding (NH4)6Mo?O24 (Fischer Scientific, 99.9%) salt to deionized water. Around 0.19 grams of the (NI LjeMoyC^ salt was mixed with 4.76 grams of deionized water to create an aqueous molybdenum solution with a concentration of 0.043 grams of salt per gram of water. Then, about 0.80 grams of this solution was added to about1.10 grams of H-CHA in a dropwise manner while stirring. The sample was then treated in flowing dry air (1.67 cm3s1g1, Air Zero, Indiana Oxygen) in a muffle furnace at 823 K for 6 hr (0.0167 K s’1).Example 6: Mo-nano-CHA synthesis

[0055] Mo-nano-CHA (Mo / Al = 0.26) was prepared by incipient wet impregnation (IWI).First, an aqueous solution was prepared by adding (NH4)6Mo?O24 (Fischer Scientific, 99.9%) salt to deionized water. Around 0.13 grams of the (NH4)6Mo?O24 salt was mixed with 5.00 grams of deionized water to create an aqueous molybdenum solution with a concentration of 0.0274 grams of salt per gram of water. Then, about 1.19 grams of this solution was added to about 0.80 grams of H-nano-CHA in a dropwise manner while stirring. The sample was then treated in flowing dry air (1.67 cm3s1g’1, Air Zero, Indiana Oxygen) in a muffle furnace at 823 K for 6 hr (0.0167 K s’1).Example 7 : Mo-nanosheet-CHA synthesis

[0056] Mo-nanosheet-CHA (Mo / Al = 0.17) was prepared by incipient wet impregnation (IWI). First, an aqueous solution was prepared by adding (NH4EMO7O24 (Fischer Scientific, 99.9%) salt to deionized water. Around 0.079 grams of the (NH4)6Mo?O24 salt was mixed with 6.36 grams of deionized water to create an aqueous molybdenum solution with a concentration of 0.073 grams of salt per gram of water. Then, about 2.20 grams of this solution was added to about 0.91 grams of H-nanosheet-CHA in a dropwise manner while stirring. The sample was then treated in flowing dry air (1.67 cm3s'1g1, Air Zero, Indiana Oxygen) in a muffle furnace at 823 K for 6 hr (0.0167 K s’1). The elemental compositions of the Mo-zeolites are shown in Table 1.Example 8: Mo-meso-CHA synthesis

[0057] Mo-meso-CHA (Mo / Al = 0.20) was prepared by incipient wet impregnation (IWI).First, an aqueous solution was prepared by adding (NH4EMO7O24 (Fischer Scientific, 99.9%) salt to deionized water. Around 0.406 grams of the (NH4)6Mo?O24 salt was mixed with 4.59 grams of deionized water to create an aqueous molybdenum solution with a concentration of 0.073 grams of salt per gram of water. Then, about 0.24 grams of this solution was added to about 0.49 grams of H-meso-CHA in a dropwise manner while stirring. The sample was then treated in flowing dry air (1.67 cm3s’1g’1, Air Zero, Indiana Oxygen) in a muffle furnace at 823 K for 6 hr (0.0167 K s’1). The elemental compositions of the Mo-zeolites are shown in Table 1.

[0058] Table 1. Catalyst properties of Mo- zeolite samples.“Catalysts after IWI of Mo and air treatment (823 K, 6 hr).

[0059] Elemental analysis was performed by inductively coupled plasma optical emission spectrometry (ICP-OES) using a Thermo Scientific iCAP 7000 Plus Series ICP-OES. Around 0.02-0.04 g of sample was digested in 2.5 g of hydrofluoric (HF) acid (48 wt %, Alfa Aesar) for 48 hr and then diluted in 50 g of deionized water (18.2 MQ). For ICP analysis, 10 g of the digested sample was mixed with 0.3 g of HNO3 (70 wt%, Sigma-Aldrich) before analysis.

[0060] Hydrogen (H ) TPR was performed to characterize the type and number of Mo species in the Mo-CHA and Mo-MFI zeolites. Hydrogen temperature programmed reduction (H2 TPR) experiments were performed using a Micromeritics Autochem II 2920 equipped with a thermal conductivity detector (TCD) for quantification of H2 consumed. The quantification method was validated with a Ag2O standard, which was able to quantify -88% of the theoretical value. Mo-zeolite samples (0.050 g) were loaded into a quartz U-tube reactor supported between two plugs of quartz wool, and a clam-shell furnace controlled the temperature measured by a thermocouple above the sample bed. A 2-propanol (Sigma Aldrich, 99.9%) N2 slurry mixture was placed to remove water produced during the reduction. Samples were pretreated in flowing air (0.5 cm3s’1, Air Zero, Indiana Oxygen) to a range of temperatures (773-1023 K) for 2 hr, cooled to 353 K. Then, a flow of 5% H2 in balance Ar (0.416 cm3 s-1, Certified Mixture, Indiana Oxygen) was sent through the sample until a TCD baseline was obtained followed by a temperature ramp to 1273 K (0.167 K s’1, hold 0.5 hr).

[0061] Error! Reference source not found, shows the H2 TPR characterization on the Mo-CHA zeolite catalyst, which indicates that these synthesis methods were sufficient to create ion-exchanged Mo, which are the active site precursors, on the CHA zeolite support. The high temperature feature (-1260 K) is unique to the ion-exchanged Mo species and quantification of total H2 normalized by Mo content (H2 / M0) was 2.84, indicating reduction of Mo6+to Mo°.

[0062] FIG. 2 depicts a H2 temperature programmed reduction (TPR) profile of the Mo- MFI catalyst, which indicates that these synthesis methods were sufficient to create ion- exchanged Mo, which are the active site precursors, on the MFI zeolite support. The hightemperature feature (-1260 K) is unique to the ion-exchanged Mo species and quantification of total H2 normalized by Mo content (H2 / M0) was 2.78, indicating reduction of Mo6+to Mo°. Methane DHA Reaction

[0063] Mo supported on MFI, CHA, nano-CHA, meso-CHA, and nanosheet-CHA catalysts were pelletized and sieved to obtain particles between 180-250 pm. Catalyst samples (0.3-0.75 g) were placed within tubular quartz reactors (12.7 mm ID) and supported between quartz wool (Fischer Scientific) plugs. Reactor temperature was controlled using a clam-shell furnace connected to and monitored by a concentric Type K thermocouple (Omega) above the catalyst bed and an additional thermocouple located at the external surface of the reactor. Molybdenum supported on MFI, CHA, nano-CHA, meso-CHA, and nanosheet-CHA catalysts were heated in Argon (UHP, 99.999%, 0.5 cm3s'1, Indiana Oxygen) to 950 K (0.167 K s’1) and held for 0.5 hr to allow stabilization of temperature. Then, a CHr / Ar (95 / 5 vol%, Certified Mixture, Indiana Oxygen) was diluted with Ar to introduce a stream of 60 vol% CH4 and 40 vol% Ar to the reactor. The total flow rate and catalyst loading were adjusted to achieve Mo contact times between 10-18 mol (mol Mo) • s • (mol CH4)1. Transfer lines from the reactor outlet were heated (>423 K) to prevent condensation of products (i.e., benzene, naphthalene). Reactor effluent analysis and quantification was performed using a gas chromatograph (GC Agilent 6890) equipped with a capillary column (DB-1, 50 m x 320 pm x 5 pm) connected to a flame ionization detector (FID) for hydrocarbons and a packed pre-column (Supelco , 3 m x 3.2 mm x 2.1 mm) followed by a packed column (Supelco 60 / 80 Carboxen 1000, 4.5 m x 3.2 mm) connected to a thermal conductivity detector (TCD) for Ar, CH4, CO, and H2. The GC precolumn was flushed with He after 0.16 hr of the injection to remove accumulated hydrocarbons.

[0064] Methane DHA catalytic measurements were performed on the Mo-zeolites by flowing 60 kPa CH4 (in balance Ar) to the catalyst bed and to let it deactivate until -80-90% of the initial rate was observed. Then, lines were flushed with Ar (UHP, 99.999%, 0.5 cm3s’1, Indiana Oxygen) and temperature was cooled to 823 K (0.25 hr) before introducing air (0.25 cm3s’1, Air Zero, Indiana Oxygen) for 6 hr into the reactor to regenerate the catalyst. After the regeneration step, temperature was increased to 950 K (0. 167 K s’1) under flowing Ar and held for 0.5 hr before introducing the flow of 60 kPa CH4 to start the consecutive reaction.Benzene formation rates

[0065] Benzene formation rates were measured with varying crystallite size and compared to rates measured on Mo-MFI zeolites. During initial time-on-stream, methane carburized the ion-exchanged Mo species, which is evident by the low values of the carbon balance and the formation of CO. FIG. 3 shows methane conversion (♦) and carbon yield (0) for a singlemethane DHA run on Mo-MFI. Reaction conditions were 950 K, 60 / 40 (vol / vol) CI h / Ar, 115 kPa total pressure, 11.8 (mol Mo) s (mol CH4)1contact time.

[0066] Carbon yield was calculated for all reactions using all the hydrocarbon products (i.e., ethane, ethylene, benzene, toluene, and naphthalene) normalized by the inlet methane flow rate. The time corresponding to the maximum value of the carbon yield is taken as the initial benzene formation rate, and this value is compared for each successive reactionregeneration cycle.

[0067] FIG. 4 A shows forward rates of benzene formation measured on the Mo-CHA, Mo- nano-CHA, Mo-meso-CHA, and Mo-nanosheet-CHA catalysts, normalized by the initial forward rate of benzene formation measured on Mo-MFI. The rates measured on the Mo-CHA zeolite samples were normalized by the rates measured on Mo-MFI and are shown in FIG. 4A. Rates increased with decreasing particle size with Mo-nanosheet-CHA having rates ~6x lower than Mo-MFI (but 4.5x higher than Mo-CHA). On CHA zeolites with the same crystallite size, rates are higher on the CHA zeolite with mesoporosity (Mo-meso-CHA). These results suggest that active sites involved in benzene formation are located at or close to external crystallite surfaces, where benzene does not experience diffusion restrictions from egressing from the CHA micropores. It was surprisingly and unexpectedly discovered that these rates and benzene selectivity (as shown in Fig. 4B) on Mo-nanosheet-CHA and Mo-meso-CHA are the highest reported for any Mo-CHA zeolite catalyst.

[0068] Reaction-regeneration cycle studies were then performed using the Mo-MFI, Mo- nanosheet-CHA, and Mo-meso-CHA zeolites. The initial benzene formation rate was normalized by the rate measured on the first methane DHA reaction run, which is shown in FIG. 5 for Mo-MFI, FIG. 6 for Mo-nanosheet-CHA, and FIG. 7 for Mo-meso-CHA. More particularly, FIG. 5 shows the initial forward rate of benzene formation measured after a given number of reaction-regeneration cycles on Mo-MFI, normalized by the initial forward rate of benzene formation measured in the first reaction-regeneration cycle. Reaction conditions were 950 K, 60 / 40 (vol / vol) CH4 / Ar, 115 kPa total pressure, 17.5 (mol Mo) s (mol CH4)1contact time. Regeneration conditions were 823 K, Air Zero, 6 hr. Argon flush in between reactionregeneration steps.

[0069] FIG. 6 shows the initial forward rate of benzene formation measured after a given number of reaction-regeneration cycles on Mo-nanosheet-CHA, normalized by initial forward rate of benzene formation measured in the first reaction-regeneration cycle. Reaction conditions were 950 K, 60 / 40 (vol / vol) CH4 / Ar, 115 kPa total pressure, 14 (mol Mo)- s- (molCH4)1contact time. Regeneration conditions were 823 K, Air Zero, 6 hr. Argon flush in between reaction-regeneration steps.

[0070] FIG. 7 shows the initial forward rate of benzene formation measured after a given number of reaction-regeneration cycles on Mo-meso-CHA, normalized by initial forward rate of benzene formation measured in the first reaction-regeneration cycle. Reaction conditions were 950 K, 90 / 10 (vol / vol) CH Ar, 115 kPa total pressure, 14 (mol Mo) s (mol CH4)1contact time. Regeneration conditions were 823 K, Air Zero, 6 hr. Argon flush in between reactionregeneration steps. As shown in the figures, the initial benzene forward rates measured using Mo-meso-CHA did not decrease over the course of 6 reaction-regeneration cycles, while Mo- MFI showed an irreversible deactivation (-50%) with successive cycles of reactionregeneration. Thus, the Mo-meso-CHA zeolite demonstrated an improved lifetime compared to the Mo-MFI catalyst.

[0071] It was unexpectedly and surprisingly discovered that the addition of Mo to nanosheet-CHA or meso-CHA zeolites provided high selectivity to aromatics (mainly benzene and naphthalene) during methane DHA reactions, compared to other Mo-CHA zeolite catalysts. It was also unexpectedly and surprisingly discovered that benzene formation rates (per Mo) increased systematically with decreasing CHA crystallite size due to an increase in the fraction of active sites at or near the external crystal surface. It was also unexpectedly and surprisingly discovered that the measured rates on Mo- nanosheet CHA did not decrease over 13 reactionregeneration cycles, indicating a significant improvement in stability compared to Mo-MFI catalysts used for 10 reaction-regeneration cycles. It was also unexpectedly and surprisingly discovered that benzene formation rates (per Mo) increased on CHA zeolites with similar crystallite size but with presence of mesopores due to alleviated diffusion constraints for bulky aromatic products. It was also unexpectedly and surprisingly discovered that the measured rates on Mo-meso-CHA did not decrease over 6 reaction-regeneration cycles, indicating a significant improvement in stability compared to Mo-MFI catalysts used for 10 reaction-regeneration cycles.

[0072] Other specific embodiments provided herein can further include any one or more of the following numbered paragraphs 1-16:

[0073] Embodiment 1 : A method for making a Mo-nanosheet-CHA and Mo-meso-CHA catalyst, comprising preparing an aqueous solution comprising one or more structure directing agents, mixing the aqueous solution with at least one silicon precursor and at least one aluminum precursor to provide a synthesis gel; recovering crystalline solids from the synthesis gel, wherein the crystalline solids consist of CHA zeolite crystallites; depositing a source ofmolybdenum onto the CHA zeolite crystallites to provide Mo-CHA zeolite crystallites having an average particle size of 1 nm to 200 nm for nanosheet-CHA and >1 pm for meso-CHA and containing a plurality of CHA zeolite pores; and carburizing the Mo-CHA zeolite crystallites at a temperature of 500°C to 900°C and a pressure of 80-100 kPa in the presence of methane (CH4) to form Mo carbide domains within the CHA zeolite pores.

[0074] Embodiment 2: The method according to embodiments 1, wherein the source of molybdenum is deposited onto the CHA zeolite crystallites by incipient wet impregnation (IWI) or by creating a physical mixture.

[0075] Embodiment 3 : The method according to embodiments 1 or 2, wherein the source of molybdenum is MoOa.

[0076] Embodiment 4: The method according to any embodiments 1 to 3, wherein the Mo carbide domains are ion-exchanged Mo species that are located on or within the CHA zeolite crystallites,

[0077] Embodiment 5: The method of any claim 1 to 4, wherein the one or more structure directing agents comprise N,N,N-trimethyl-l-adamantylammonium (TMAda+) cations, sodium (Na+) cations, or a combination thereof.

[0078] Embodiment 6: The method according to any embodiments 1 to 5 wherein recovering crystalline solids from the synthesis gel comprises treating the synthesis gel in air at a temperature of about 60°C to 240°C and then contacting the heated gel with an ionexchange cation.

[0079] Embodiment 7 : The method according to embodiment 6, wherein the ion-exchange cation comprises NH4+.

[0080] Embodiment 8: The method according to embodiment 1, wherein a Si: Al weight ratio of the at least one silicon precursor and at least one aluminum precursor ranges from 20- 100.

[0081] Embodiment 9: The method according to embodiment 1, wherein the aluminum precursor is selected from the group consisting of aluminum hydroxide, aluminum nitrate, aluminosilicate, combinations thereof and derivatives thereof.

[0082] Embodiment 10: The method according to embodiment 1, wherein the silicon precursor is selected from the group consisting of colloidal silica, a silicon alkoxide compound, fumed silica, amorphous silica, aluminosilicate, combinations thereof and derivatives thereof.

[0083] Embodiment 11: A method for dehydroaromatization, comprising contacting the Mo-nanosheet-CHA catalyst of claim 1 with methane at a temperature of 600°C to 800°C to provide one or more aromatics.

[0084] Embodiment 12: The method according to embodiment 11, wherein the zeolite catalyst and methane are contacted in a fixed bed gas-phase reactor.

[0085] Embodiment 13: The method according to embodiments 11 or 12, wherein the zeolite catalyst and methane are contacted in a dual bed circulating fluidized bed reactor system to allow for continuous regeneration of deactivated catalyst using hot air or IE.

[0086] Embodiment 14: The method according to any embodiments 11 to 13, wherein contacting the zeolite catalyst of claim 1 with methane at temperature of 600°C to 800°C comprises contacting the zeolite catalyst of claim 1 with a 2: 1 volume ratio of methane and argon, at a GHSV of 4,500 ml / hr g-cat for about 1 hour.

[0087] Embodiment 15: The method according to any embodiments 11 to 14, wherein the methane is derived from natural gas or shale gas.

[0088] Embodiment 16: The method according to any embodiments 11 to 14, wherein the aromatics consist essentially of benzene.

[0089] All patents and patent applications, test procedures (such as ASTM methods, UL methods, and the like), and other documents cited herein are fully incorporated by reference to the extent such disclosure is not inconsistent with this disclosure and for all jurisdictions in which such incorporation is permitted.

[0090] Certain embodiments and features have been described using a set of numerical upper limits and a set of numerical lower limits. It should be appreciated that ranges including the combination of any two values, e.g., the combination of any lower value with any upper value, the combination of any two lower values, and / or the combination of any two upper values are contemplated unless otherwise indicated. Certain lower limits, upper limits and ranges appear in one or more claims below. All numerical values are “about” or “approximately” the indicated value, meaning the values take into account experimental error, machine tolerances and other variations that would be expected by a person having ordinary skill in the art.

[0091] The foregoing has also outlined features of several embodiments so that those skilled in the art can better understand the present disclosure. Those skilled in the art should appreciate that they can readily use the present disclosure as a basis for designing or modifying other methods or devices for carrying out the same purposes and / or achieving the same advantages of the embodiments disclosed herein. Those skilled in the art should also realizethat such equivalent constructions do not depart from the spirit and scope of the present disclosure, and that they can make various changes, substitutions, and alterations herein without departing from the spirit and scope of the present disclosure, and the scope thereof is determined by the claims that follow.

[0092] Various terms have been defined above. To the extent a term used in a claim is not defined above, it should be given the broadest definition persons in the pertinent art have given that term as reflected in at least one printed publication or issued patent. Furthermore, all patents, test procedures, and other documents cited in this application are fully incorporated by reference to the extent such disclosure is not inconsistent with this application and for all jurisdictions in which such incorporation is permitted.

Claims

CLAIMSWHAT IS CLAIMED IS:

1. A method for making a Mo-nanosheet-CHA catalyst, comprising: preparing an aqueous solution comprising one or more structure directing agents, mixing the aqueous solution with at least one silicon precursor and at least one aluminum precursor to provide a synthesis gel; recovering crystalline solids from the synthesis gel, wherein the crystalline solids consist of CHA zeolite cry stallites; depositing a source of molybdenum onto the CHA zeolite crystallites to provide Mo- CHA zeolite crystallites having an average particle size of 1 nm to 200 nm and containing a plurality of CHA zeolite pores; and carburizing the Mo-CHA zeolite crystallites at a temperature of 500°C to 900°C and a pressure of 80-100 kPa in the presence of methane (CH4) to form Mo carbide domains within the CHA zeolite pores.

2. A method for making a Mo-meso-CHA catalyst, comprising: preparing an aqueous solution comprising one or more structure directing agents, mixing the aqueous solution with at least one silicon precursor and at least one aluminum precursor to provide a synthesis gel; recovering crystalline solids from the synthesis gel, wherein the crystalline solids consist of CHA zeolite crystallites: depositing a source of molybdenum onto the CHA zeolite crystallites to provide Mo- CHA zeolite crystallites having an average particle size of 500 nm to 2,000 nm and containing a plurality of CHA zeolite pores larger than 2 nanometers in diameter; and carburizing the Mo-CHA zeolite crystallites at a temperature of 500°C to 900°C and a pressure of 80-100 kPa in the presence of methane (CH4) to form Mo carbide domains within the CHA zeolite pores.

3. The method of claim 1 , wherein the source of molybdenum is deposited onto the CHA zeolite crystallites by incipient wet impregnation (IWI) or by creating a physical mixture.

4. The method of claims 1 or 2, wherein the source of molybdenum is MoOr.

5. The method of claims 1 or 2, wherein the Mo carbide domains are ion-exchanged Mo species that are located on or within the CHA zeolite crystallites,6. The method of claims 1 or 2, wherein the one or more structure directing agents comprise N,N,N-trimethyl-l-adamantylammonium (TMAda+) cations, sodium (Na+) cations, or a combination thereof.

7. The method of claims 1 or 2 wherein recovering crystalline solids from the synthesis gel comprises treating the synthesis gel in air at a temperature of about 60°C to 240°C and then contacting the heated gel with an ion-exchange cation.

8. The method of claim 7, wherein the ion-exchange cation comprises NH4+.

9. The method of claim 1 or 2, wherein a Si:Al weight ratio of the at least one silicon precursor and at least one aluminum precursor ranges from 20-100.

10. The method of claim 1 or 2, wherein the aluminum precursor is selected from the group consisting of aluminum hydroxide, aluminum nitrate, aluminosilicate, combinations thereof and derivatives thereof.

11. The method of claim 1 or 2, wherein the silicon precursor is selected from the group consisting of colloidal silica, a silicon alkoxide compound, fumed silica, amorphous silica, aluminosilicate, combinations thereof and derivatives thereof.

12. A method for dehydroaromatization, comprising: contacting the Mo-nanosheet-CHA catalyst of claim 1 with methane at a temperature of 600°C to 800°C to provide one or more aromatics.

13. The method of claim 12, wherein the zeolite catalyst and methane are contacted in a fixed bed gas-phase reactor.

14. The method of claims 12 or 13, wherein the zeolite catalyst and methane are contacted in a dual bed circulating fluidized bed reactor system to allow for continuous regeneration of deactivated catalyst using hot air or H2.

15. The method of claims 12 or 13, wherein contacting the zeolite catalyst of claim 1 with methane at temperature of 600°C to 800°C comprises contacting the zeolite catalyst of claim 1 with a 2: 1 volume ratio of methane and argon, at a GHSV of 4,500 ml / hr g-cat for about 1 hour.

16. The method of claims 12 or 13, wherein the methane is derived from natural gas or shale gas.

17. The method of claims 12 or 13, wherein the aromatics consist essentially of benzene.

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