WO2017125839A1 - Fused ceramic nano- or micro catalysts having high surface area - Google Patents

Abstract

A millable hollow catalytic nano- or micromaterial, methods of making the millable hollow catalytic nano- or micromaterial and uses thereof are described. The millable hollow catalytic nano- or micromaterial can include a ceramic shell defining an enclosed hollow space. The ceramic shell can include a catalytic metal dispersed throughout the shell. The hollow catalytic nano- or micromaterial, when milled, has a surface area of at least 5 m²/g.

Description

FUSED CERAMIC NANO- OR MICRO CATALYSTS HAVING HIGH SURFACE

AREA

CROSS REFERENCE TO RELATED APPLICATIONS

[0001] This application claims the benefit of priority of U.S. Provisional Patent Application No. 62/280,385, filed January 19, 2016, which is hereby incorporated by reference in its entirety.

BACKGROUND OF THE INVENTION

A. Field of the Invention

[0002] The invention generally concerns catalytic material that can be used to catalyze chemical reactions (e.g., non-oxidative methane coupling reactions). In particular, the material can be a hollow millable nano- or micromaterial having a fused ceramic shell with catalytic metal present in the crystal lattice of the shell. After milling, the nano- or micromaterial can have a surface area of at least 5 m²/g of catalyst.

B. Description of Related Art [0003] In heterogeneous catalysis, the phase of the catalyst differs from that of the reactants. Many heterogeneous catalysis systems include catalytic metals. In general, during a heterogeneous catalysis reaction, the reactants diffuse to the catalytic site, adsorb on the catalytic site, undergo a chemical reaction to form a product, and then the product desorbs from the catalytic site. Thus, the amount of catalytic sites available to the reactant directly affects the amount of product produced. To maximize the amount of catalytic sites, catalysts with large surface areas are generally employed.

[0004] In conventional catalysts, ceramics such as alumina and silica are widely used as catalytic support materials due to their refractoriness and high surface area resulting from the porosity. One of the issues with such ceramic support materials is an inherent limitation on the amount of catalytic surface area that can be produced when the porosity has been reduced or eliminated. By way of example, silica can be mechanically milled through high speed attrition milling to increase surface area. However, silica is relatively soft and can be difficult to mill through mechanical milling (e.g., attrition milling). This type of milling results in a catalytic surface area of about 1 m²/g for catalysts supported by ceramic materials such as fused silica. In one particular example, U. S. Patent Publication No. 2014/0336432 describes amorphous, metal lattice-doped catalysts with Si bonded with C, N, or O that was ground and sieved to a 20 to 30 mesh. One of the issues associated with grinding and milling of ceramics is contamination from the grinding media (e.g., alumina, zirconia and carbides) due to the long milling times, which can deactivate the catalyst (e.g., coking of the catalyst can occur due to surface acidity from the contaminations) [0005] Other non-milling processes to create high surface area catalysts have been disclosed. For example, U. S. Patent No. 8,889,583 describes an emulsion aggregation process to produce solid ceramic catalysts having a particle surface area of 1 m²/g to about 1000 m²/g. Some of the issues associated with these non-milling processes are time, expense, and complexities involved with the processing steps (e.g., high temperature processing to insert the metal into the lattice). Therefore, the commercial scalability of such processes is limited.

SUMMARY OF THE INVENTION

[0006] A discovery has been made that provides a solution to the problems associated with obtaining a ceramic supported catalyst that has a high surface area per gram of catalyst (m²/g or m²/g. cat.). The solution is premised on the preparation of a nano- or micromaterial having a particular structure that can be mechanically milled or collision milled down to have an overall surface area of at least 5 m²/g while avoiding, or minimizing, contamination during the milling process. Notably, milling times can be significantly reduced and milling efficiency can be increased. In particular, the structure of the nano- or micromaterial includes a hollow fused ceramic shell (e.g., silica) with the shell defining an enclosed hollow space (e.g., a hollow fused ceramic sphere or particle). Catalytic metal (e.g., iron, cobalt, nickel, or copper) or oxides thereof can be dispersed throughout the ceramic shell and/or incorporated into the lattice structure of the shell. This allows for more exposure of active catalytic metal sites during milling, thereby increasing the efficiency of the resulting milled catalysts. Without wishing to be bound by theory, it is believed that the nano- or microscale sized shell having the hollow space allows for more efficient mechanical milling of the shell when compared with solid non-hollow ceramic supported catalytic particles because the hollow spheres are structurally weaker than the solid spheres. Specifically, the hollow nature of the shell allows for easier crushing or grinding and avoids or limits the possibility of the ceramic (e.g., silica (Si0₂), alumina (A1₂0₃), or zirconia (Zr0₂)) sintering during the milling process. The end result is a milled catalyst having a surface area (e.g., as determined by BET) of at least 5 m²/g. Notably, and as explained below, the thickness of the hollow fused ceramic shell can be tuned such that the resulting milled catalyst can have a desired or selected surface area (e.g., at least 5 m²/g, preferably 5 m²/g to 500 m²/g, more preferably at least 10 m²/g, and most preferably 10 m²/g to 50 m²/g).

[0007] The nano- or micromaterial of the present invention that allows for the increased surface area can be made by an elegant process. Generally (particular details are provided below), a carbonizable polymer core can be coated with ceramic material and catalytic metal or oxides or precursor material thereof to create a ceramic material/catalytic metal coating around the core. Subsequently, a carbonizable polymer shell can be formed around the ceramic material/catalytic metal coating, thereby creating an architecture where the ceramic material/catalytic metal coating is positioned in between or sandwiched by the polymer core and shell. Carbonization of the core and shell provides protection of the ceramic material/catalytic metal coating, thereby allowing for the application of sufficient temperatures to then melt the ceramic material. During this melting process, in which the ceramic material is heated to a temperature above its glass transition Tg temperature, the catalytic metal or oxides or precursors thereof, can be mixed or dispersed throughout the melted ceramic material via thermal energy. Subsequent cooling to below the Tg of the ceramic material allows for hardening or re-crystallization of the ceramic material, thereby creating a fused ceramic shell having catalytic metal or oxides or precursor materials thereof dispersed throughout the shell and/or incorporated into the lattice structure of the shell. Without wishing to be bound by theory, it is believed that formation of the carbonized core and a carbonized shell form an in situ reactor that allows for this melting and recrystallization process to be performed in a controllable manner and allows for a variety of shapes and thicknesses of the ceramic shell to be obtained. Removal of the carbonized inner core and outer carbonized shell {e.g., through oxidation) results in the millable nano- or micromaterial of the present invention.

[0008] In one aspect of the present invention, a millable hollow catalytic nano- or micromaterial is described. The millable hollow catalytic nano- or micromaterial can include a ceramic shell defining an enclosed hollow space, the ceramic shell having a catalytic metal or metal oxide, or precursor materials thereof dispersed throughout the shell. The ceramic shell can include a fused ceramic with the catalytic metal dispersed throughout the ceramic shell and/or part of the ceramic crystal lattice. Prior to milling, the hollow catalytic nano- or micromaterial can have a surface area of 0.001 to 1.0 m²/g of catalyst. After milling, the hollow catalytic nano- or micromaterial can have a surface area of at least 5 m²/g {e.g., 5 m²/g to 500 m²/g, more preferably at least 10 m²/g, and most preferably 10 m²/g to 50 m²/g). The ceramic shell can have a spherical or substantially spherical shape with a diameter of 50 nm to 100,000 nm, preferably 100 to 1000 nm, and most preferably 100 to 300 nm. A thickness of the ceramic shell can be at least 10 nm, preferably 10 nm to 1000 nm, and most preferably, 100 to 300 nm. A volume of the hollow space can be 1 nm³ to 10⁷ μιη³. The ceramic shell can be a metal oxide support for the dispersed catalytic metal. The metal oxide can be silica (Si0₂), alumina (A1₂0₃), titania (Ti0₂), zirconia (Zr0₂), germania (Ge0₂), stannic oxide (Sn0₂), gallium oxide (Ga₂0₃), zinc oxide (ZnO), hafnia (Hf0₂), yttria (Y₂0₃), lanthana (La₂0₃), ceria (Ce0₂), or any combination thereof, preferably silica, alumina titania, or zirconia. The catalytic metal can be a noble metal (e.g., silver (Ag), palladium (Pd), platinum (Pt), gold (Au), rhodium (Rh), ruthenium (Ru), rhenium (Re), Osmium (Os), or iridium (Ir)), a transition metal (e.g., copper (Cu), iron (Fe), cobalt (Co), nickel (Ni), zinc (Zn), manganese (Mn), chromium (Cr), molybdenum (Mo), tungsten (W), or tin (Sn)), or any combination or oxides or alloys thereof, and in a particular instance, Fe, Co, Ni, or Cu or alloys or oxides thereof. In a particular instance, the hollow ceramic catalytic metal nano- or micromaterial is a fused Fe-Si0₂ hollow shell. In some instances, the nano- or micromaterial consists essentially of, or consists of, the ceramic shell and catalytic metal or oxides or precursors thereof. The millable hollow catalytic nano- or micromaterial can also include a carbonized core contained within the hollow space of the ceramic shell and a carbonized shell that encompasses the ceramic shell. Oxidation of the carbonized core and the carbonized shell can remove the core and shell from the nano- or micromaterial.

[0009] Also disclosed in the context of the present invention are methods of making the millable hollow catalytic nano- or micromaterial. A method can include (a) obtaining a precursor material having a carbonized inner core, a ceramic shell having a catalytic metal dispersed throughout the ceramic shell, and a carbonized outer shell encompassing the ceramic shell; and (b) oxidizing the precursor material to remove the carbonized inner core and the carbonized outer shell to obtain the millable hollow catalytic nano- or micromaterial of the present invention. The thickness of the resulting ceramic shell having the catalytic metal or oxides or precursors thereof can be modified or tuned based on the size of the inner core and/or the thickness of the outer carbonized shell. It is believed that thinner ceramic shell with the catalytic metal results in increased surface area after milling. The carbonizable inner core can be a particle having a diameter of 1 nm to 100,000 nm and/or the ceramic shell can have a thickness of at least 10 nm, preferably 10 nm to 100 nm, or most preferably 10 nm to 50 nm. Step (a) can include (1) coating a carbonizable core with a ceramic material and the catalytic metal (the catalytic metal can be metal or an oxide thereof or catalytic metal precursor material thereof) to produce a first coated material; (2) coating the first coated material with a second coating that includes carbonizable material to produce a second coated material; (3) pyrolyzing the second coated material at a temperature of 650 °C to 850 °C to carbonize the carbonizable core and the second coating in the presence of an inert gas; and (4) subjecting the pyrolyzed material to a temperature of 1 100 °C to 2800 °C to melt the ceramic material and disperse the catalytic metal (or oxides or precursor materials thereof) throughout the ceramic material followed by cooling to obtain the precursor material of step (a). Step (a)(1) can include: (i) depositing the catalytic metal (or metal oxides or catalytic precursor materials thereof) onto the surface of the carbonizable core followed by deposition of the ceramic material onto the catalytic metal (or oxides or precursor material thereof), (ii) depositing the ceramic material onto the surface of the carbonizable core followed by deposition of the catalytic metal (or metal oxides or precursor materials thereof) onto the ceramic material, or (iii) co-depositing the ceramic material and the catalytic metal (or metal oxides or precursor material) on to the surface of the carbonizable core (e.g., through a sol gel process). In some instances, the carbonizable core from step (a)(1) and from step (a)(2) each can include a carbon containing polymer (e.g., thermoset or thermoplastic polymers such as a polystyrene polymer, a siloxane-based polycarbonate polymer, polystyrene, polyethylene, polypropylene, polyacrylate, polyamide, polyimide, polyethylene terephthalate, polybutylene terephthalate, PMMA, PCCD, PCTG, polysulfones, polyetherimides, polyphenyl oxide, and thermosets such as Polyurethane, epoxides, etc. and any pyrolyzable polymers or a combination thereof. In a particular instance, the ceramic material in step (a)(1) can be a metal oxide (e.g., silica (Si0₂), alumina (A1₂0₃), titania (Ti0₂), zirconia (Zr0₂), germania (Ge0₂), stannic oxide (Sn0₂), gallium oxide (Ga₂0₃), zinc oxide (ZnO), hafnia (Hf0₂), yttria (Y₂0₃), lanthana (La₂0₃), ceria (Ce0₂), or any combination thereof), in particular silica. The catalytic metal in step (a)(1) can be a noble metal (e.g., silver (Ag), palladium (Pd), platinum (Pt), gold (Au), rhodium (Rh), ruthenium (Ru), rhenium (Re), Osmium (Os), or iridium (Ir)), a transition metal (e.g., copper (Cu), iron (Fe), cobalt (Co) nickel (Ni), zinc (Zn), manganese (Mn), chromium (Cr), molybdenum (Mo), tungsten (W), or tin (Sn)), or any combination or oxides or alloys thereof, and in a particular instance, iron. In a particular instance, the hollow ceramic catalytic metal nano- or micromaterial is Fe-Si0₂. Step (b) can include subjecting the precursor material to a temperature of 600 °C to 800 °C in the presence of oxygen to remove the carbonized inner core and the carbonized outer shell to obtain the millable hollow catalytic nano- or micromaterial. In some instances, the millable hollow catalytic nano- or micromaterial can be cooled and, optionally, treated with an acid. Treatment with acid can remove bulk metals and provide single site metal moieties in the hollow ceramic catalytic nano- or micromaterial. The milled nano- or micromaterial can have a surface area of at least 5 m²/g, preferably 5 m²/g to 500 m²/g, more preferably at least 10 m²/g, and most preferably 10 m²/g to 50 m²/g.

[0010] In yet another instance, methods for using the millable hollow catalytic nano- or micromaterial described herein are disclosed. A method can include obtaining a milled form of the hollow catalytic nano- or micromaterial, contacting the milled nano- or micromaterial with a reactant feed to catalyze the reaction, and producing a product feed. The chemical reaction can include a carbon-hydrogen bond activation reaction, a hydrocarbon cracking reaction, a hydrogenation of hydrocarbon reaction, and/or a dehydrogenation of hydrocarbon reaction, 3 -way catalytic environmental mitigation reaction for automobiles, air remediation reactions or combinations thereof. [0011] Systems for producing a chemical product using the millable hollow catalytic nano- or micromaterial described herein are also disclosed. The system can include (a) an inlet for a reactant feed; (b) a reaction zone that is configured to be in fluid communication with the inlet, wherein the reaction zone can include a catalyst milled from the millable hollow catalytic nano- or micromaterial described herein; and (c) an outlet configured to be in fluid communication with the reaction zone and configured to remove a product stream from the reaction zone. The reaction zone can be a continuous flow reactor selected from a fixed- bed reactor, a fluidized reactor, or a moving bed reactor.

[0012] Also disclosed in the context of the present invention are embodiments 1-47. Embodiment 1 describes a millable hollow catalytic nano- or micromaterial that includes a ceramic shell defining an enclosed hollow space, the ceramic shell having a catalytic metal dispersed throughout the shell, wherein the hollow catalytic nano- or micromaterial, when milled, has a surface area of at least 5 m2/g. Embodiment 2 is the millable hollow catalytic nano- or micromaterial of embodiment 1, wherein the ceramic shell is a fused ceramic. Embodiment 3 is the millable hollow catalytic nano- or micromaterial of any one of embodiments 1 to 2, wherein a portion of the catalytic metal is present in the crystal lattice of the ceramic shell. Embodiment 4 is the millable hollow catalytic nano- or micromaterial of any one of embodiments 1 to 3, wherein the ceramic shell has a spherical shape with a diameter of 50 nm to 100,000 nm, preferably 100 nm to 1000 nm, or most preferably 100 nm to 300 nm. Embodiment 5 is the millable hollow catalytic nano- or micromaterial of any one of embodiments 1 to 4, wherein the ceramic shell has a thickness of at least 10 nm, preferably 10 nm to 1000 nm, or most preferably 100 nm to 300 nm. Embodiment 6 is the millable hollow catalytic nano- or micromaterial of any one of embodiments 1 to 5, wherein the volume of the hollow space is 1 nm3 to 1 x 107 μιη3. Embodiment 7 is the millable hollow catalytic nano- or micromaterial of any one of embodiments 1 to 6, wherein the nano- or micromaterial, when milled, has a surface area of area of 5 m2/g to 500 m2/g, preferably at least 10 m2/g, or more preferably 10 m2/g to 50 m2/g. Embodiment 8 is the millable hollow catalytic nano- or micromaterial of embodiment 7, wherein the nano- or micromaterial is milled and has a surface area of at least 5 m2/g. Embodiment 9 is the millable hollow catalytic nano- or micromaterial of embodiment 8, wherein the milled nano- or micromaterial has a surface area of 5 m2/g to 500 m2/g, preferably at least 10 m2/g, or more preferably 10 m2/g to 50 m2/g. Embodiment 10 is the millable hollow catalytic nano- or micromaterial of any one of embodiments 1 to 9, wherein the ceramic shell is a metal oxide support for the dispersed catalytic metal. Embodiment 11 is the millable hollow catalytic nano- or micromaterial of embodiment 10, wherein the metal oxide is selected from silica (Si02), alumina (A1203), titania (Ti02), zirconia (Zr02), germania (Ge02), stannic oxide (Sn02), gallium oxide (Ga203), zinc oxide (ZnO), hafnia (Hf02), yttria (Y203), lanthana (La203), ceria (Ce02), or any combination thereof. Embodiment 12 is the millable hollow catalytic nano- or micromaterial of embodiment 11, wherein the metal oxide is silica (Si02). Embodiment 13 is the millable hollow catalytic nano- or micromaterial of any one of embodiments 1 to 12, wherein the catalytic metal is a noble metal, a transition metal, or any combination or oxides or alloys thereof. Embodiment 14 is the millable hollow catalytic nano- or micromaterial of embodiment 13, wherein the noble metal is silver (Ag), palladium (Pd), platinum (Pt), gold (Au), rhodium (Rh), ruthenium (Ru), rhenium (Re), Osmium (Os), or iridium (Ir). Embodiment 15 is the millable hollow catalytic nano- or micromaterial of any one of embodiments 13 or 14, wherein the transition metal is copper (Cu), cobalt (Co), iron (Fe), nickel (Ni), zinc (Zn), manganese (Mn), chromium (Cr), molybdenum (Mo), tungsten (W), or tin (Sn). Embodiment 16 is the millable hollow catalytic nano- or micromaterial of embodiment 15, wherein the transition metal is Fe and the metal oxide is silica (Si02). Embodiment 17 is the millable hollow catalytic nano- or micromaterial of any one of embodiments 1 to 16, wherein the nano- or micromaterial consists essentially of, or consists of, the ceramic shell. Embodiment 18 is the millable hollow catalytic nano- or micromaterial of any one of embodiments 1 to 17, wherein the ceramic shell consists essentially of, or consists of, ceramic material and the catalytic metal. Embodiment 19 is the millable hollow catalytic nano- or micromaterial of any one of embodiments 1 to 18, further including a carbonized core contained within the hollow space of the ceramic shell and a carbonized shell that encompasses the ceramic shell. Embodiment 20 is the millable hollow catalytic nano- or micromaterial of embodiment 19, wherein the carbonized core and the carbonized shell are removable through an oxidation reaction.

[0013] Embodiment 21 is a method of making the millable hollow catalytic nano- or micromaterial of any one of embodiments 1 to 20. The method can include (a)obtaining a precursor material having a carbonized inner core, a ceramic shell having a catalytic metal dispersed throughout the ceramic shell, and a carbonized outer shell encompassing the ceramic shell; and (b) oxidizing the precursor material to remove the carbonized inner core and the carbonized outer shell to obtain the millable hollow catalytic nano- or micromaterial of any one of embodiments 1 to 20. Embodiment 22 is The method of embodiment 21, wherein step (a) further includes (a)(1) coating a carbonizable core with a ceramic material and the catalytic metal to produce a first coated material; (a)(2) coating the first coated material with a second coating that includes carbonizable material to produce a second coated material; (a)(3) pyrolyzing the second coated material at a temperature of 650 °C to 850 °C to carbonize the carbonizable core and the second coating in the presence of an inert gas; and (a)(4) subjecting the pyrolyzed material to a temperature of 1110 °C to 2800 °C to melt the ceramic material and disperse the catalytic metal throughout the ceramic material followed by cooling the ceramic material to obtain the precursor material. Embodiment 23 is the method of embodiment 22, wherein step (a)(1) includes depositing the catalytic metal or metal oxide onto the surface of the carbonizable core followed by deposition of the ceramic material onto the catalytic metal. Embodiment 24 is the method of embodiment 22, wherein step (a)(1) includes depositing the ceramic material onto the surface of the carbonizable core followed by deposition of the catalytic metal or metal oxide onto the ceramic material. Embodiment 25 is the method of embodiment 22, wherein step (a)(1) can include co-depositing the ceramic material or ceramic material precursor, and catalytic metal or metal oxide or catalytic metal precursor on to the surface of the carbonizable core. Embodiment 26 is the method of embodiment 22, wherein step (a)(1) can include depositing the catalytic metal or metal oxide and the ceramic material onto the surface of the carbonizable core through a sol gel process. Embodiment 27 is the method of any one of embodiments 22 to 26, wherein the carbonizable core from step(a)(l) and the carbonizable material from step (a)(2) each include a carbon containing polymer. Embodiment 28 is the method of embodiment 27, wherein the carbon containing polymer is a thermoplastic polymer or thermoset polymer, or a combination thereof. Embodiment 29 is the method of embodiment 28, wherein the thermoplastic polymer includes polystyrene, a siloxane-based polycarbonate polymer, polyethylene, polypropylene, polyacrylate, polyamide, polyimide, polyethylene terephthalate, polybutylene terephthalate, polymethyl methacrylate, poly(l,4-cyclohexylenedimethylene 1,4- cyclohexanedicarboxylate), poly(cyclohexylene dimethylene terephthalate)glycol, polysulfone, polyetherimide, or polyphenyl oxide, or co-polymers or melts thereof. Embodiment 30 is the method of embodiment 27, wherein the thermoset polymer can include polyurethane, an epoxide, or a pyrolyzable polymer, or co-polymers or melts thereof. Embodiment 31 is The method of any one of embodiments 22 to 30, wherein the ceramic material in step (a)(1) is a metal oxide. Embodiment 32 is the method of embodiment 31, wherein the metal oxide is selected from silica (Si02), alumina (A1203), titania (Ti02), zirconia (Zr02), germania (Ge02), stannic oxide (Sn02), gallium oxide (Ga203), zinc oxide (ZnO), hafnia (Hf02), yttria (Y203), lanthana (La203), ceria (Ce02), or any combination thereof. Embodiment 33 is the method of embodiment 27, wherein the metal oxide is silica (Si02). Embodiment 34 is the method of any one of embodiments 22 to 33, wherein the catalytic metal in step (a)(1) is a noble metal, a transition metal, or any combination or oxides or alloys thereof. Embodiment 35 is the method of embodiment 34, wherein the noble metal is silver (Ag), palladium (Pd), platinum (Pt), gold (Au), rhodium (Rh), ruthenium (Ru), rhenium (Re), Osmium, (Os), or iridium (Ir). Embodiment 36 is the method of any one of embodiments 34 to 35, wherein the transition metal is copper (Cu), iron (Fe), cobalt (Co), nickel (Ni), zinc (Zn), manganese (Mn), chromium (Cr), molybdenum (Mo), tungsten (W), or tin (Sn). Embodiment 37 is the method of embodiment 36, wherein the transition metal is Fe and the metal oxide is silica. Embodiment 38 is the method of any one of embodiments 21 to 37, wherein the carbonizable inner core in step (a) is a particle having a diameter of 1 nm to 100,000 nm. Embodiment 39 is the method of any one of embodiments 21 to 38, wherein the ceramic shell has a thickness of at least 10 nm, preferably 10 nm to 100 nm, or more preferably 10 nm to 50 nm. Embodiment 40 is the method of any one of embodiments 21 to 39, wherein step (b) includes subjecting the precursor material to a temperature of 600 °C to 800 °C in the presence of oxygen to remove the carbonized inner core and the carbonized outer shell to obtain the millable hollow catalytic nano- or micromaterial. Embodiment 41 is the method of embodiment 40, further including cooling the millable hollow catalytic nano- or micromaterial and optionally treating it with an acid. Embodiment 42 is the method of any one of embodiments 21 to 41, further including milling the hollow catalytic nano- or micromaterial, wherein the milled nano- or micromaterial has a surface area of at least 5 m²/g, preferably 5 m²/g to 500 m²/g, more preferably at least 10 m²/g, or most preferably 10 m²/g to 50 m²/g. Embodiment 43 is the method of embodiment 42, wherein milling is collision milling.

[0014] Embodiment 44 is a method for using the millable hollow catalytic nano- or micromaterial of any one of embodiments 1 to 20 in a chemical reaction, the method comprising: obtaining a milled form of the hollow catalytic nano- or micromaterial; and contacting the milled nano- or micromaterial with a reactant feed to catalyze the reaction; and producing a product feed. Embodiment 45 is the method of embodiment 43, wherein the chemical reaction can include a carbon-hydrogen bond activation reaction, a hydrocarbon cracking reaction, a hydrogenation of hydrocarbon reaction, a dehydrogenation of hydrocarbon reaction, 3-way catalytic environmental mitigation reaction for automobiles, air remediation reactions or combinations thereof. [0015] Embodiment 46 is a system for producing a chemical product, the system comprising: (a) an inlet for a reactant feed; (b) a reaction zone that is configured to be in fluid communication with the inlet, wherein the reaction zone comprises a catalyst milled from the millable hollow catalytic nano- or micromaterial of any one of embodiments 1 to 21 ; and (c) an outlet configured to be in fluid communication with the reaction zone and configured to remove a product stream from the reaction zone. Embodiment 47 is the system of embodiment 46, wherein the reaction zone is a continuous flow reactor selected from a fixed- bed reactor, a fluidized reactor, or a moving bed reactor.

[0016] The following includes definitions of various terms and phrases used throughout this specification. [0017] "Millable," "milling", "milled" refers to a material that is reduced in size (e.g. breaking a material into multiple pieces) through the application of force. Non-limiting examples of milling include, grinding, crushing, rolling, pulverizing and collisions in gas streams from opposite directions.

[0018] "Fuse" or "fused ceramic" refers to ceramic material that has been subjected to temperatures that cause the ceramic material to sinter or melt (e.g., temperatures above the Tg of the ceramic material) and then harden or recrystallize (e.g., cooling the ceramic material to temperatures below their respective Tg). This allows catalytic metal or oxides or catalytic metal precursor materials thereof to be incorporated into the lattice structure of the fused ceramic material, thereby allowing for an increase in the number of exposed active catalytic metal sites when the fused ceramic material is milled.

[0019] "Surface Area" of the pre-milled and post-milled hollow catalytic nano- or micromaterial of the present invention can be determined using the Brunauer-Emmett-Teller (BET) theory. For example, ASTM C1274 or the procedure in the Examples section can be used to determine the surface area of the ceramics. The surface area of non-porous material can be estimated by the following equation: SA= 3/(rd) where r denotes the particle radium in microns, d represents the density of the material. For example, silica has a density (d) of 2.55 grams per cubic centimeter (g/cc). If the average particle size of the ground glass is 1 μπι, the surface area would be approximately 2 m²/g.

[0020] "Nanostructure" or "nanomaterial" refer to an object or material in which at least one dimension of the object or material is equal to or less than 100 nm (e.g., one dimension is 1 to 100 nm in size). In a particular aspect, the nanostructure includes at least two dimensions that are equal to or less than 100 nm (e.g., a first dimension is 1 to 100 nm in size and a second dimension is 1 to 100 nm in size). In another aspect, the nanostructure includes three dimensions that are equal to or less than 100,000 nm (e.g., a first dimension is 1 to 100 nm in size, a second dimension is 1 to 100 nm in size, and a third dimension is 1 to 100 nm in size). The shape of the nanostructure can be of a wire, a particle (e.g., having a substantially spherical shape), a rod, a tetrapod, a hyper-branched structure, a tube, a cube, or mixtures thereof. "Nanoparticles" include particles having an average diameter size of 1 to 100 nanometers.

[0021] "Microstructure" or "micromaterial" refers to an object or material in which at least one dimension of the object or material is equal to or less than 100,000 nm (100 microns) and greater than 100 nm (e.g., one dimension is greater than 100 nm and less than 100,000 nm in size). In a particular aspect, the microstructure includes at least two dimensions that are equal to or less than 100,000 nm and greater than 100 nm (e.g., a first dimension is greater than 100 nm and less than 100,000 nm in size and a second dimension is greater than 100 nm and less than 100,000 nm in size). In another aspect, the microstructure includes three dimensions that are equal to or less than 100,000 nm and greater than 100 nm (e.g., a first dimension is greater than 100 nm and less than 100,000 nm in size, a second dimension is greater than 100 nm and less than 100,000 nm in size, and a third dimension is greater than 100 nm and less than 100,000 nm in size). The shape of the microstructure can be of a wire, a ribbon, a particle, a sphere, a rod, a tetrapod, a hyperbranched structure, or mixtures thereof.

[0022] The terms "about" or "approximately" are defined as being close to as understood by one of ordinary skill in the art. In one non-limiting embodiment, the terms are defined to be within 10%, preferably within 5%, more preferably within 1%, and most preferably within 0.5%.

[0023] The terms "wt.%," "vol.%," or "mol.%" refers to a weight, volume, or molar percentage of a component, respectively, based on the total weight, the total volume of material, or total moles, that includes the component. In a non-limiting example, 10 grams of component in 100 grams of the material is 10 wt.% of component.

[0024] The term "substantially" and its variations are defined to include ranges within 10%, within 5%, within 1%, or within 0.5%.

[0025] The terms "inhibiting" or "reducing" or "preventing" or "avoiding" or any variation of these terms, when used in the claims and/or the specification includes any measurable decrease or complete inhibition to achieve a desired result.

[0026] The term "effective," as that term is used in the specification and/or claims, means adequate to accomplish a desired, expected, or intended result.

[0027] The use of the words "a" or "an" when used in conjunction with any of the terms "comprising," "including," "containing," or "having" in the claims, or the specification, may mean "one," but it is also consistent with the meaning of "one or more," "at least one," and "one or more than one."

[0028] The words "comprising" (and any form of comprising, such as "comprise" and "comprises"), "having" (and any form of having, such as "have" and "has"), "including" (and any form of including, such as "includes" and "include") or "containing" (and any form of containing, such as "contains" and "contain") are inclusive or open-ended and do not exclude additional, unrecited elements or method steps.

[0029] The catalysts of the present invention can "comprise," "consist essentially of," or "consist of particular ingredients, components, compositions, etc. disclosed throughout the specification. With respect to the transitional phase "consisting essentially of," in one non- limiting aspect, a basic and novel characteristic of the catalysts of the present invention is that the hollow ceramic catalytic nano- or micromaterial can be milled to produce a surface area of at least 5 m²/g of catalyst.

[0030] Other objects, features and advantages of the present invention will become apparent from the following figures, detailed description, and examples. It should be understood, however, that the figures, detailed description, and examples, while indicating specific embodiments of the invention, are given by way of illustration only and are not meant to be limiting. Additionally, it is contemplated that changes and modifications within the spirit and scope of the invention will become apparent to those skilled in the art from this detailed description. In further embodiments, features from specific embodiments may be combined with features from other embodiments. For example, features from one embodiment may be combined with features from any of the other embodiments. In further embodiments, additional features may be added to the specific embodiments described herein.

BRIEF DESCRIPTION OF THE DRAWINGS

[0031] Advantages of the present invention may become apparent to those skilled in the art with the benefit of the following detailed description and upon reference to the accompanying drawings.

[0032] FIGS. 1A-1B are schematics of steps of an embodiment of a method to make milled hollow ceramic catalytic nano- or micromaterials. FIG. 1A is an illustration of a millable hollow ceramic catalytic nano- or micromaterial of the present invention and a process of milling said nano- or micromaterial. FIG. IB is a schematic to make the millable hollow ceramic catalytic nano- or micromaterial.

[0033] FIG. 2 is a schematic of a system for use of the hollow ceramic catalytic nano- or micromaterial in a chemical reaction. [0034] While the invention is susceptible to various modifications and alternative forms, specific embodiments thereof are shown by way of example in the drawings and may herein be described in detail. The drawings may not be to scale.

DETAILED DESCRIPTION OF THE INVENTION

[0035] A discovery has been made that provides for a hollow fused ceramic catalytic nano- or micromaterial that can be milled into smaller particles and produce a catalytic material having a surface area of at least 5 m²/g of catalyst. This increased surface area provides for a more efficient catalyst due, in part, to the increased number of exposed active catalytic metal sites present on the surface of the milled material. Notably, the architecture of the hollow fused ceramic nano- or micromaterial of the present invention avoids the issues seen with currently available catalytic materials that have an inherent limitation on the amount of catalytic surface area that can be produced through mechanical milling (about 1 m²/g cat.) and reduces or eliminates contamination of the particles during milling. In particular, the nano- or microscale size, hollow core, and fused ceramic shell having catalytic metal (or oxides or precursors thereof) dispersed throughout and/or incorporated into the lattice structure of the ceramic shell provides for a more efficient nano- or micromaterial that can be milled while avoiding or limiting the possibility of sintering during the milling process which can reduce the resulting surface area of the milled catalyst.

[0036] These and other non-limiting aspects of the present invention are discussed in further detail in the following sections.

A. Structure of the Millable Hollow Ceramic Catalytic Nano- or Micromaterials and Milling Processes

[0037] Referring to FIG. 1A, a hollow ceramic catalytic nano- or micromaterial 102 having a hollow space (or hollow core) 104 and a ceramic catalytic shell 106 that includes catalytic metal or metal oxides or precursors thereof (not shown) dispersed throughout the shell 106 is illustrated. The ceramic shell can be a fused ceramic shell such that the catalytic metal/oxides/precursors thereof can be incorporated into the lattice framework structure of the shell 106. This incorporation into the lattice framework can allow for exposure of catalytic metal active sites on the surface of the nano- or micromaterial 102 when milled 116. The milled nano- or micromaterial 116 can have a surface area of at least 5 m²/g of catalyst, preferably 5 m²/g to 500 m²/g, more preferably at least 10 m²/g, and most preferably 10 m²/g to 50 m²/g. In some instances, the surface area can range from 5, 10, 15, 20, 25, 30, 35, 40, 45, 50, 55, 60, 65, 70, 75, 80, 85, 90, 95, 100, 125, 150, 175, 200, 225, 250, 275, 300, 325, 350, 375, 400, 425, 450, 475, 500 m²/g or any range or value there between. The volume of the hollow space 104 can range from 1 nm³ to 1 x 10⁷ μπι³. The thickness of the shell 106 can be modified or tuned to have a desired thickness. In preferred instances, the thickness is at least 10 nm, preferably 10 nm to 1000 nm, most preferably 100 nm to 300 nm, or 10, 20, 30, 40, 50, 60, 70, 80, 90, 100, 110, 120, 130, 140, 150, 160, 170, 180, 190, 200, 210, 220, 230, 240, 250, 260, 270, 280, 290, 300, 325, 350, 375, 400, 425, 450, 475, 500, 525, 550, 575, 600, 625, 650, 675, 700, 725, 750, 775, 800, 825, 850, 875, 900, 925, 950, 975, 1000 nm, or any value or range there between.

B. Preparation of the Millable Hollow Ceramic Catalytic Nano- or Micromaterial 1. Process Steps [0038] Referring to FIG. IB, the hollow ceramic catalytic nano- or micromaterial 102 of the present invention can be prepared by coating a carbonizable core 118 with a ceramic material and a catalytic metal (or oxide or precursor thereof) to produce a first coating 120 such that a first coated material 122 is obtained. This coating process can be implemented with hydrothermal processes, solvothermal processes, sol-gel method, emulsion polymerization, microemulsion polymerization, ultrasound assisted in-situ surface polymerization, Stober method and so forth. The processing steps can be modified as desired. By way of example, the catalytic metal or metal oxide or precursor thereof can be deposited onto the surface of the carbonizable core followed by deposition of the ceramic material onto the catalytic metal. Alternatively, the ceramic material can be deposited onto the surface of the carbonizable core followed by deposition of the catalytic metal or metal oxide or precursor thereof onto the ceramic material. In another aspect, the ceramic material or ceramic material precursor, and catalytic metal or metal oxide or catalytic metal precursor can be deposited on to the surface of the carbonizable core at the same time such as through a sol gel process. Surfactants (e.g., CTAB, PVP, etc.) or other agents and/or controlled surface charge can be used in many of the processes to stabilized particle formation.

[0039] First coated material 122 can then be coated with a second coating 126 to produce a second coated material 128 using known polymer coating techniques such as physical vapor deposition, plasma treatment, chemical vapor deposition, sol-gel processes, supercritical fluid process, suspension polymerization, and emulsification and solvent evaporation techniques. By way of example, first coated material 122 can be dispersed in a solution having carbon- containing compounds (e.g., a solution of one or more monomers, initiator, and/or a crosslinking agent) and subjected to conditions suitable to polymerize the carbon-containing compounds to produce the second coated material 128. By way of example, the silica coated particles can be dispersed in mineral spirits to form a slurry. An aliquot amount of 4- vinylpyridine can be added to the slurry and the silicate coated particle can be sonicated. Then divinylbenzene (e.g., in an amount that is five times the amount of the 4-vinylpyridine) and 5 wt.% of monomer amount of radical initiator benzylperoxide can be added to the slurry. The slurry can be heated to 90 °C until the polymerization is complete (e.g., overnight). The polymer coated particles then can be filtered and dried in an oven at 120 °C for 4 hours.

[0040] Second coated material 128 can then be subjected to a temperature of 650 °C to 850 °C (or 650 °C, 660 °C, 670 °C, 680 °C, 690 °C, 700 °C, 710 °C, 720 °C, 730 °C, 740 °C, 750 °C, 760 °C, 770 °C, 780 °C, 790 °C, 800 °C, 810 °C, 820 °C, 830 °C, 840 °C, 850 °C, or any range or value there between) to carbonize the carbonizable core 1 18 and the second coating 126 to obtain a carbonized core 1 10 and a carbonized shell 130, thereby producing a carbonized material 132 that has coating 122 positioned between the carbonized core 1 10 and carbonized shell 130. In preferred instances, the second coating 122 does not substantially change or react during the carbonization process.

[0041] The carbonized material 132 can then be heated to a temperature sufficient to melt the ceramic material in the first coating 122 and mix the catalytic metal (or oxides or precursors thereof) in the melted ceramic material via thermal energy from the heating process. For example, the carbonized material 132 can be heated under vacuum or under an inert atmosphere to the melting or Tg temperature of the ceramic material (e.g., 1 1 10 °C to 2800 °C) for a desired period of time (e.g., 2 to 10 hours) to form precursor material 134. Table 1 lists the melting points of non-limiting examples of metal oxides that can be used for coating 120. Without wishing to be bound by theory, it is believed that the carbonized core 1 10 and carbonized shell 130 provide an in situ "reactor and "mold". The reactor portion allows the ceramic material and catalytic metal to be heated in a controlled environment to form a melt. Once the melt is formed the catalytic metal can be dissolved in, or dispersed throughout, the molten ceramic material. Upon cooling the melt forms a fused crystal lattice that has the catalytic metal dispersed throughout the crystal lattice and/or incorporated into the crystal lattice. Thus, the carbonized core 1 10 and carbonized shell 130 form a mold. Tuning the shape and size of the mold can provide hollow ceramic catalytic nano- or micromaterial 102 of desired shapes and sizes. Table 1

[0042] Upon cooling to a temperature of about 650 °C to 750 °C, or 700 °C, the precursor material 134 can be contacted with an oxidant (e.g., oxygen, oxygen-enriched air, or air) for a desired period of time (e.g., 6 to 12 hours) to convert the carbonized material to carbon oxides to form hollow ceramic catalytic nano- or micromaterial 102.

[0043] The produced hollow ceramic catalytic nano- or micromaterial 102 can then be milled to form nano- or micromaterial 1 16 with a high surface area. In some embodiments, the milled nano- or micromaterial 1 16 can be further treated with acid (e.g., nitric acid) to remove any bulk metals and to ensure the formation of single metal catalytic sites. By way of example, an iron-silica (Fe-Si0₂) catalyst can have two Fe iron atoms (bulk metal) next to each other on the exposed surface of the nano- or micromaterial 1 16 and one Fe atom from the bulk metal is removed by contacting the particles with an acid. Such a washing provides a single catalytic metal site for use in chemical reactions.

[0044] Milling of the nano- or micromaterials 102 can be performed by using known methods. In preferred instances, mechanical milling can be used, non-limiting examples of which can include ball milling, vibration milling, attrition milling, and roller milling. Mechanical ball milling is typically accomplished by placing solid spheres (balls) made of a suitably hard material in a cylindrical tumbler along with the material to be milled. The axis of the cylindrical tumbler can be horizontal and the tumbler and its contents can be rotated about the axis over an extended period of time (e.g., 2, 3, 4, 5 or more hours) to pulverize the material to be milled. By comparison, vibrational milling is similar to ball milling except that the milling vessel is vigorously shaken in a back and forth motion alone or in combination with a lateral motion that produces a "figure 8" path. Vibration milling typically relies only on the extremely high-energy collisions between rapidly moving milling balls rather than the collisions between the balls and the tumbler wall, as used in ball milling. Since vibrator mills can often shake canisters at a rate of approximately 1200 RPMs, often producing ball speeds of upwards of 5 m/s, vibrational milling commonly yields the desired reduction in particle size at a rate one order of magnitude faster than that of ball milling. Attrition milling relies on rapidly spinning paddles to stir the milling balls present in the milling vessel. The rate of size reduction observed is often similar to the rate of reduction observed for vibrator mills of similar size; however, due to the necessity of a cooling system this type of milling is often limited in its capabilities to systems that can be milled in liquid media. Roller milling is a process that relies on fracturing caused by stress induced in the system from the compression of materials between two rolling bars or cylinders. The milling process typically reduces the average particle size until equilibrium is reached, at which point no further size reduction is observed. In a particular instance collision (jet) milling can be used. By way of example, jet milling is typically accomplished by feeding the millable particles into a steam or other carrier gas such as nitrogen, air or carbon dioxide. Under pressure, the particles can be carried by the high speed gas stream, through a ceramic lined pipe, fly out of two nozzles that are directed towards each other from the opposite directions. The particles are then collided among themselves and shattered.

2. Materials Used a. Carbonizable Materials [0045] The carbonizable core 1 18 and carbonizable second coating 120 can include any carbon containing material that can be converted into carbonized material. While shown as a sphere, the carbonizable core 1 18 can have any shape (e.g., a particle, a rod, an ellipsoid, a square, and the like). Non-limiting examples of carbonizable material include carbon containing polymers, polymer precursors, or blends thereof. Polymers can include thermoset polymers, thermoplastic polymers, or blends thereof. Polymer precursors can be monomers of the thermoplastic polymers or thermoset polymers, or blends thereof. Thermoplastic polymers include those that can become pliable or moldable above a specific temperature, and return back to a more solid state upon cooling. There are a wide range of various thermoplastic or thermoset polymers and blends thereof that can be used to make the carbonizable core 1 18 and the second coating 126. These polymers or monomeric precursors are available from various commercial vendors. Non-limiting examples of thermoplastic polymers include polyethylene terephthalate (PET), a polycarbonate (PC) family of polymers, a siloxane-based polycarbonate polymer, polybutylene terephthalate (PBT), poly(l,4- cyclohexylidene cyclohexane-l,4-dicarboxylate) (PCCD), glycol modified polycyclohexyl terephthalate (PCTG), poly(phenylene oxide) (PPO), polypropylene (PP), polyethylene (PE), polyvinyl chloride (PVC), polystyrene (PS), polyacrylate polymers, polymethyl methacrylate (PMMA), polyamide (PA), polyimides, polyethyleneimine or polyetherimide (PEI) and their derivatives, thermoplastic elastomer (TPE), terephthalic acid (TPA) elastomers, poly(cyclohexanedimethylene terephthalate) (PCT), polyethylene naphthalate (PEN), poly suf ones, polystyrene sulfonate (PSS), sulfonates of polysulfones, poly ether ether ketone (PEEK), poly ether ketone ketone (PEKK), acrylonitrile butyldiene styrene (ABS), polyphenylene sulfide (PPS), co-polymers thereof, or blends thereof. Non-limiting examples of thermoset polymers that can be used to make a thermoset polymeric matrix include unsaturated polyester resins, polyurethanes, polyoxybenzylmethylenglycolanhydride (Bakelite), duroplast, urea-formaldehyde, diallyl-phthalate, epoxy resin, epoxy vinylesters, polyimides, cyanate esters of polycyanurates, dicyclopentadiene, phenolics, benzoxazines, co-polymers thereof, or blends thereof. In some instances, the carbonizable core 118 is a polystyrene bead and the second coating 126 is a thermoset or thermoplastic polymer. In other instances, the carbonizable core can be manufactured using emulsion polymerization methods. b. Ceramic and Catalytic Metal Materials

[0046] The ceramic material can be a metal oxide. Non-limiting examples include those listed in Table 1 above or combinations thereof can be used. These materials can be obtained through chemical preparations or purchased from Sigma Aldrich® (St. Louis, Missouri, USA), Alfa-Aeaser (Ward Hill, Massachusetts, USA), and Strem Chemicals (Newburyport, Massachusetts, USA)). In general, the ceramic sols of the present invention may be prepared by the hydrolysis and peptization of the corresponding organo-metallic compounds in an aqueous medium. Non-limiting organo-metallic compounds are aluminum nitrates, aluminum alkoxides, and the aluminum sec-butoxides, ethoxides, and methoxides. In a particular instance, silica components may be prepared from the corresponding silanes, such as tetraethyl orthosilicate (TEOS), tetramethyl orthosilicate (TMOS), methyltriethoxysilane (MTES), methyltrimethoxysilane (MTMS), vinyltrimethoxysilane (VTMS), 3- aminopropyltrimethoxysilane (APS), gamma-methacryloxypropyltrimethoxysilane (gamma- MAPTS).

[0047] The catalytic metal or oxides or precursors thereof can include noble metals, transition metals, or any combinations or any alloys thereof. Noble metals include gold (Au), silver (Ag), palladium (Pd), platinum (Pt), rhodium (Rh), ruthenium (Ru), rhenium (Re), iridium (Ir), osmium (Os), or any combinations or alloys thereof. Transition metals include iron (Fe), copper (Cu), cobalt (Co), nickel (Ni), zinc (Zn), manganese (Mn), chromium (Cr), molybdenum (Mo), tungsten (W), or tin (Sn), or any combinations or alloys thereof. In some embodiments, the catalytic metal includes 1, 2, 3, 4, 5, 6, or more transition metals and/or 1, 2, 3, 4 or more noble metals. The metals can be obtained from metal precursor compounds. For example, the metals can be obtained as a metal nitrate, a metal amine, a metal chloride, a metal coordination complex, a metal sulfate, a metal phosphate hydrate, metal complex, or any combination thereof. Examples of metal precursor compounds include, chloroauric acid, nickel nitrate hexahydrate, nickel chloride, cobalt nitrate hexahydrate, cobalt chloride hexahydrate, cobalt sulfate heptahydrate, cobalt phosphate hydrate, platinum (IV) chloride, ammonium hexachloroplatinate (IV), sodium hexachloroplatinate (IV) hexahydrate, potassium hexachloroplatinate (IV), or chloroplatinic acid hexahydrate. These metals or metal compounds can be purchased from any chemical supplier such as Sigma-Aldrich (St. Louis, Missouri, USA), Alfa-Aeaser (Ward Hill, Massachusetts, USA), and Strem Chemicals (Newburyport, Massachusetts, USA).

[0048] The amount of catalytic metal to be used can depend, inter alia, on the catalytic activity of the catalyst. In some embodiments, the amount of catalytic metal present in the nano- or micromaterial 102 can range from 0.01 to 100 parts by weight of catalytic metal per 100 parts by weight of nano- or micromaterial, from 0.01 to 5 parts by weight of catalytic metal per 100 parts by weight of catalyst. If more than one catalytic metal is used, the molar percentage of one metal can be 1 to 99 molar % of the total moles of catalytic metals in the ceramic shell.

C. Use of the Milled Hollow Fused Ceramic Catalytic Nano- or Micromaterial [0049] The produced hollow fused ceramic catalytic nano- or micromaterial of the present invention can be used in a variety of chemical reactions. Non-limiting examples of chemical reactions include a carbon-hydrogen bond activation reaction, a hydrocarbon cracking reaction, a hydrogenation of hydrocarbon reaction, and/or a dehydrogenation of hydrocarbon reaction, 3-way catalytic environmental mitigation reaction for automobiles, air remediation reactions or combinations thereof. In a particular instance, a milled hollow Fe- Si0₂ nano- or micromaterial having a high surface area can be used in the methane coupling (oligomerization) reactions. Specifically, a non-oxidative coupling of methane reaction. The methods used to prepare the hollow fused ceramic catalytic nano- or micromaterial can tune the size of the core, the catalytic metal particles, dispersion of the catalytic metal-containing particles in the core, the porosity and pore size of the shell or the thickness of the shell to produce highly reactive and stable hollow fused ceramic catalytic nano- or micromaterial with a high surface area for use in a chosen chemical reaction. [0050] Referring to FIG. 2, a system 200 is illustrated, which can be used to convert methane to higher order hydrocarbons (e.g., C₂+ hydrocarbons, ethylene, ethane, propylene, propane, butene, butane, benzene, long chain hydrocarbons, and the like). The system 200 can include a feed source 202, a reactor 204, and a collection device 206. The feed source 202 can be configured to be in fluid or gas communication with the reactor 204 via an inlet 208 on the reactor. The feed can include methane alone or mixed with a carrier gases such as nitrogen or argon can also be used in the reactant stream. As explained above, the feed source 202 can be configured such that it regulates the amount of reactant feed entering the reactor 202. As shown, the methane mixture feed source 302 is one unit feeding into one inlet 208, however, it should be understood that the number of inlets and/or separate feed sources can be adjusted to reactor sizes and/or configurations and/or type of reaction. The reactor 204 can include a reaction zone 210 having the hollow fused ceramic catalytic nano- or micromaterial 212 in particulate form. The reactor can include various automated and/or manual controllers, valves, heat exchangers, gauges, etc. necessary for the operation of the reactor. For example, the reactor can have flow controllers to provide the reactant (e.g., methane) feed at a desired weight hourly space velocity. The reactor can be have the necessary insulation and/or heat exchangers to heat or cool the reactor as necessary. The amounts of the reactants and nano- or microparticles 212 used can be modified as desired to achieve a given amount of product produced by the system 200. Non-limiting examples of continuous flow reactors that can be used include fixed-bed reactors, fluidized reactors, bubbling bed reactors, slurry reactors, rotating kiln reactors, moving bed reactors or any combinations thereof when two or more reactors are used.

[0051] In preferred aspects, reactor 204 is a continuous flow fixed-bed reactor. The reactor 204 can include an outlet 214 configured to be in fluid communication with the reaction zone and configured to remove a first product stream that includes higher order hydrocarbons (e.g., C₂+ hydrocarbons, alkenes, alkanes, aromatics, long chain hydrocarbons, and the like) from the reaction zone 210. Reaction zone 210 can further include the reactant feed and the first product stream. The products produced can include higher order hydrocarbons (e.g., ethylene, butane, long chain hydrocarbons) and hydrogen. The collection device 206 can be in fluid communication with the reactor 204 via the outlet 214. Both the inlet 208 and the outlet 214 can be opened and closed as desired. The collection device 206 can be configured to store, further process, or transfer desired reaction products (e.g., higher order hydrocarbons) for other uses. In a non-limiting example, collection device can be a separation unit or a series of separation units that are capable of separating the liquid components/gaseous components from the gaseous components from the product stream. The resulting products (e.g., ethylene) can be sold, stored or used in other processing units as a feed source. Still further, the system 200 can also include a heating/cooling source 216. The heating/cooling source 216 can be configured to heat or cool the reaction zone 210 to a temperature sufficient and pressure to convert the reactant (e.g., methane) in the reactant feed to the desired product (e.g., ethylene). Non-limiting examples of a heating/cooling source 216 can be a temperature controlled furnace or an external, electrical heating block, heating coils, or a heat exchanger.

EXAMPLES

[0052] The present invention will be described in greater detail by way of specific examples. The following examples are offered for illustrative purposes only, and are not intended to limit the invention in any manner. Those of skill in the art will readily recognize a variety of noncritical parameters which can be changed or modified to yield essentially the same results. Prophetic Example 1

(Method of Making the Hollow Core-Shell Material)

[0053] The following sections are prophetic descriptions of the steps used to make a hollow core-shell fused Fe-Si0₂ material.

A. Method of Making the Core-Shell Material (First Coating) [0054] An aqueous polystyrene suspension (100 ml, 1 wt.% of polymer in water) will be sonicated to disperse the polystyrene. The suspension will then be sparged with N₂ to remove any trace amount of dissolved oxygen. TEOS (0.1 mole) and of FeCl₂ (0.0005 mole) solution will be added into the suspension, followed by addition of an aqueous urea solution (100 ml, 1 molar). The mixed suspension will be heated to 80 °C under a flowing nitrogen atmosphere for 8 hours. After the reaction is complete, the coated material can be filtered and dried at 120 °C overnight. B. Method of Applying the Second Coating To the Core-Shell Material

[0055] The above collected material will be dispersed in 250 ml mineral spirits by sonication to form a suspension. 4-vinylpyridine (1 mL), divinylbenzene (10 ml of a 55 wt.% solution) and benzoyl peroxide (1 g) can be added to the suspension. The suspension will be heated to 120 °C for 8 hours under a nitrogen atmosphere. After the polymerization is completed, the suspension can be filtered and the double-coated material can be collected.

C. Method of Carbonizing and Removal of Carbonized Material

[0056] The double-coated material will be heated to 700 °C in a tubular furnace under a a flowing nitrogen atmosphere for 6 hours. As the carbonization proceeds, the color of the material will turn black. Then the material will be heated to 1800 °C and maintained at that temperature for 12 hours. As the carbonization completes, the temperature can be reduced to 700 °C and the flowing nitrogen can be switched to air, to start the oxidation of carbon. The material will be held at 700 °C under an air atmosphere until all the carbon material is oxidized (e.g., the material turns white) and forms the hollow nano- or micromaterial. The hollow nano- or micromaterial will be collected after cooling to room temperature.

D. Milling of Hollow Nano- or Micromaterial

[0057] The above collected hollow nano- or microparticles (50 gram) will be suspended in ethanol and the suspension can be loaded into a plastic container (250 mL). Silicon carbide (SiC, 100 g) milling balls with size of 1 mm will be added in the bottle. The bottle will be rolled for 72 hours. After milling is done, the crushed Fe-SiC>2 glass powder will be separated from the milling media, collected, and used as a catalyst.

Example 2

(Determination of Surface Area)

[0058] The sample will be preconditioned to remove physically bonded impurities from the surface of the powder using degassing or outgassing methods. The sample will be heated to an elevated temperature in conjunction with vacuum or continuously flowing inert gas.

[0059] The specific surface area of a material will then be determined by the physical adsorption of a gas (typically nitrogen, krypton, or argon) onto the surface of the sample at cryogenic temperatures (typically liquid nitrogen or liquid argon temperatures). The choice of gas to be used will be dependent on the expected surface area and the properties of the sample. Once the amount of adsorbate gas has been measured (either by a volumetric or continuous flow technique), calculations which assume a monomolecular layer of the known gas are applied. Evaluation of the BET surface area must be done in the linear region of the BET plot, which could be systematically evaluated using the Rouquerol transform.

Claims

A millable hollow catalytic nano- or micromaterial comprising a ceramic shell defining an enclosed hollow space, the ceramic shell having a catalytic metal dispersed throughout the shell, wherein the hollow catalytic nano- or micromaterial, when milled, has a surface area of at least 5 m²/g.

The millable hollow catalytic nano- or micromaterial of claim 1, wherein the ceramic shell is a fused ceramic.

The millable hollow catalytic nano- or micromaterial of claim 1, wherein a portion of the catalytic metal is present in the crystal lattice of the ceramic shell.

The millable hollow catalytic nano- or micromaterial of claim 1, wherein:

(a) the ceramic shell has a spherical shape with a diameter of 50 nm to 100,000 nm, or 100 nm to 1000 nm, or 100 nm to 300 nm;

(b) the ceramic shell has a thickness of at least 10 nm, or 10 nm to 1000 nm, or 100 nm to 300 nm;

(c) the volume of the hollow space is 1 nm³ to 1 x 10⁷ μπι³; and/or

(d) the nano- or micromaterial, when milled, has a surface area of area of 5 m²/g to 500 m²/g, or at least 10 m²/g, or 10 m²/g to 50 m²/g.

The millable hollow catalytic nano- or micromaterial of claim 1, wherein the nano- or micromaterial is milled and has a surface area of at least 5 m²/g, or 5 m²/g to 500 m²/g, or at least 10 m²/g, or 10 m²/g to 50 m²/g.

The millable hollow catalytic nano- or micromaterial of claim 1, wherein the ceramic shell is a metal oxide support for the dispersed catalytic metal.

The millable hollow catalytic nano- or micromaterial of claim 6, wherein the catalytic metal is a noble metal, a transition metal, or any combination or oxides or alloys thereof.

The millable hollow catalytic nano- or micromaterial of claim 7, wherein the transition metal is Fe and the metal oxide is silica (Si0₂).

The millable hollow catalytic nano- or micromaterial of claim 1, wherein the nano- or micromaterial consists essentially of, or consists of, the ceramic shell.

A method of making the millable hollow catalytic nano- or micromaterial of any one of claim 1, the method comprising:

(a) obtaining a precursor material having a carbonized inner core, a ceramic shell having a catalytic metal dispersed throughout the ceramic shell, and a carbonized outer shell encompassing the ceramic shell; and

(b) oxidizing the precursor material to remove the carbonized inner core and the carbonized outer shell to obtain the millable hollow catalytic nano- or micromaterial of any one of claims 1 to 20.

The method of claim 10, wherein step (a) further comprises:

(a)(1) coating a carbonizable core with a ceramic material and the catalytic metal to produce a first coated material;

(a)(2) coating the first coated material with a second coating that includes carbonizable material to produce a second coated material;

(a)(3) pyrolyzing the second coated material at a temperature of 650 °C to 850 °C to carbonize the carbonizable core and the second coating in the presence of an inert gas; and

(a)(4) subjecting the pyrolyzed material to a temperature of 1110 °C to 2800 °C to melt the ceramic material and disperse the catalytic metal throughout the ceramic material followed by cooling the ceramic material to obtain the precursor material.

The method of claim 11, wherein step (a)(1) comprises:

(i) depositing the catalytic metal or metal oxide onto the surface of the carbonizable core followed by deposition of the ceramic material onto the catalytic metal;

(ii) depositing the ceramic material onto the surface of the carbonizable core followed by deposition of the catalytic metal or metal oxide onto the ceramic material;

(iii) co-depositing the ceramic material or ceramic material precursor, and catalytic metal or metal oxide or catalytic metal precursor on to the surface of the carbonizable core; or (iv) depositing the catalytic metal or metal oxide and the ceramic material onto the surface of the carbonizable core through a sol gel process.

13. The method of claim 11, wherein the carbonizable core from step(a)(l) and the carbonizable material from step (a)(2) each comprise a carbon containing polymer.

14. The method of claim 13, wherein the carbon containing polymer is a thermoplastic polymer or thermoset polymer, or a combination thereof.

15. The method of claim 14, wherein the thermoset polymer comprises polyurethane, an epoxide, or a pyrolyzable polymer, or co-polymers or melts thereof.

16. The method of claim 11, wherein:

(i) the ceramic material in step (a)(1) is a metal oxide, or silica (Si0₂); and/or

(ii) the catalytic metal in step (a)(1) is a noble metal, a transition metal, or any combination or oxides or alloys thereof, or iron.

17. The method of any claim 10, wherein the carbonizable inner core in step (a) is a particle having a diameter of 1 nm to 100,000 nm.

18. The method of claim 10, wherein step (b) comprises subjecting the precursor material to a temperature of 600 °C to 800 °C in the presence of oxygen to remove the carbonized inner core and the carbonized outer shell to obtain the millable hollow catalytic nano- or micromaterial.

19. The method of claim 10, further comprising milling the hollow catalytic nano- or micromaterial, wherein the milled nano- or micromaterial has a surface area of at least 5 m²/g, or 5 m²/g to 500 m²/g, or at least 10 m²/g, or 10 m²/g to 50 m²/g.

20. A method for using the millable hollow catalytic nano- or micromaterial of claim 1 in a chemical reaction, the method comprising: obtaining a milled form of the hollow catalytic nano- or micromaterial; and contacting the milled nano- or micromaterial with a reactant feed to catalyze the reaction; and producing a product feed.