Improved processes reactors and catalysts for hydrocarbon pyrolysis

Abstract

A process for producing hydrogen from hydrocarbons includes contacting a hydrocarbon with a catalyst and inert particles in a reactor, producing solid carbon and hydrogen based on the contacting, removing a portion of the inert particles from the reactor, heating the portion of the inert particles in a heating loop to produce heated inert particles, returning the heated inert particles to an upper portion of the reactor, and heating the reactor during the contacting based on returning the heated inert particles.

Description

IMPROVED PROCESSES REACTORS AND CATALYSTS FOR HYDROCARBON PYROLYSIS    CROSS-REFERENCE TO RELATED APPLICATIONS

[0001] The present application claims priority to (and the benefit under 35 U.S.C. Section 119(e) of) U.S. Provisional Application No. 63 / 553,902 filed on February 15, 2024 and entitled, “IMPROVED PROCESSES REACTORS AND CATALYSTS FOR HYDROCARBON PYROLYSIS,” the entire disclosure of which is incorporated herein by reference. STATEMENT REGARDING GOVERNMENTALLY SPONSORED RESEARCH OR DEVELOPMENT

[0002] None. BACKGROUND

[0003] The pyrolysis of low-cost hydrocarbon feedstocks including petroleum and natural gas produces solid carbon and gas phase molecular hydrogen. For example, the conversion can occur according to the following equation: ^(CH2m)^^^ Csolid ^mH2

[0004] This reaction has the potential for producing a hydrogen product without carbon dioxide which is a major challenge in society today. In the absence of a catalyst, the reaction requires very high temperatures (T >1000 °C) and there are many technical challenges associated with heat management in such high temperature processes. To date there have been no significant commercial processes using pyrolysis to produce hydrogen as a primary product. SUMMARY

[0005] In some embodiments, a process for producing hydrogen from hydrocarbons comprises contacting a hydrocarbon with a catalyst and inert particles in a reactor,1    producing solid carbon and hydrogen based on the contacting, removing a portion of the inert particles from the reactor, heating the portion of the inert particles in a heating loop to produce heated inert particles, returning the heated inert particles to an upper portion of the reactor, and heating the reactor during the contacting based on returning the heated inert particles.

[0006] In some embodiments, a process for producing hydrogen from hydrocarbons comprises combusting a reactant in a reactor to produce heat within the reactor, contacting a hydrocarbon with a catalyst in the reactor, producing solid carbon and hydrogen based on the contacting, and heating the reactor during the contacting based on the combusting.

[0007] In some embodiments, a process for producing hydrogen from hydrocarbons comprises contacting a hydrocarbon with a catalyst in a reactor, producing solid carbon and hydrogen based on the contacting, removing a portion of the solid carbon and catalyst during the contacting, and introducing a catalyst promoter during the contacting.

[0008] These and other features will be more clearly understood from the following detailed description taken in conjunction with the accompanying drawings and claims. BRIEF DESCRIPTION OF THE DRAWINGS

[0009] For a more complete understanding of the present disclosure, reference is now made to the following brief description, taken in connection with the accompanying drawings and detailed description:

[0010] Figure 1 schematically illustrates the basic transformations of hydrocarbons to solid carbon with any carbon oxides made into chemical products enabled by the invention embodiments herein.

[0011] Figure 2 schematically illustrates a process embodiment where heat is provided by external circulation of an inert material.

[0012] Figure 3 schematically illustrates a process embodiment where heat is provided by hydrogen combustion.

[0013] Figure 4 schematically illustrates a process embodiment where heat is provided2    by hydrocarbon combustion and use of carbon oxides for chemicals.

[0014] Figures 5 schematically illustrates a dual circulating fluidized bed with heat integration and external heating according to some embodiments.

[0015] Figures 6 schematically illustrates a dual circulating fluidized bed with internal structures, heat integration, and external heating according to some embodiments.

[0016] Figures 7 schematically illustrates a dual circulating fluidized bed with internal structures, heat integration, and external heating according to some embodiments.

[0017] Figures 8A and 8B each schematically illustrate a dual circulating fluidized bed with internal cyclones, heat integration, and external heating according to some embodiments.

[0018] Figures 9 schematically illustrates addition of heat through the external solids circulation.

[0019] Figures 10A and 10B schematically illustrate fluidization regimes for the fluidized bed reactor.

[0020] Figures 11 schematically illustrates a process with hydrogen combustion combined with pyrolysis to produce carbon and chemicals including hydrogen.

[0021] Figures 12 schematically illustrates a process with hydrogen combustion producing hot steam combined with pyrolysis to produce solid carbon and hydrogen.

[0022] Figures 13 schematically illustrates a process with hydrogen combustion by selective introduction of oxygen into hydrogen rich zones combined with pyrolysis to produce carbon and chemicals.

[0023] Figures 14 schematically illustrates that either steam produced by hydrogen combustion or oxygen directly can be introduced into regions of the reactor with high hydrogen partial pressures to minimize CO production.

[0024] Figures 15 schematically illustrates the precombustion of hydrogen within a ceramic monolith prior to introducing the hot steam product into the fluidized bed reactor.

[0025] Figures 16 schematically illustrates a circulating fluidized bed where hydrogen combustion to make hot steam is used to provide heat to the pyrolysis reaction.

[0026] Figures 17 schematically illustrates the oxidation of hydrogen halides to provide3    the reaction heat and catalyst for the hydrocarbon pyrolysis reaction.

[0027] Figures 18 shows commercial scale facilities utilizing hydrogen halides.

[0028] Figures 19 schematically illustrates a circulating fluidized bed where hydrogen halide precombustion is used to provide heat to the pyrolysis reactor.

[0029] Figures 20A-20C schematically illustrate the process of metal catalyst conversion from an oxide to active nanoparticle catalyst.

[0030] Figures 21 schematically illustrates a circulating fluidized bed where internal cyclones maintain high density particles within main reactor, and external cyclone diverts catalyst / carbon particles into an external packed bed reactor potentially for further reaction.

[0031] Figures 22A-22B schematically illustrates how oxidation can increase the carbon to metal ratio by disrupting the carbon capsule.

[0032] Figures 23A-23C shows data from carbon deposited on iron catalyst compared to carbon on inert particles.

[0033] Figures 24 schematically illustrates how macroscopic iron sources are fragmented into active catalyst particles.

[0034] Figures 25 schematically illustrates how within the counter current circulating inert bed reactor metal oxides added to the reactor are reduced to active catalysts,

[0035] Figures 26A-26D shows experimental data of carbons produced from different precursors.

[0036] Figure 27 shows schematically a reactor configuration with heat addition by hydrogen combustion within a monolith prior to introducing hot steam into reactor.

[0037] Figure 28 shows schematically a reactor configuration with heat addition by hydrogen combustion within a monolith prior to introducing hot steam into reactor.

[0038] Figures 29 schematically illustrates an autothermal reactor configuration with an internal circulation of inert solids heated by hydrogen combustion to make hot steam is used to provide heat to the pyrolysis reaction.

[0039] Figures 30A and 30B illustrate another embodiment of a reactor with an internal recirculation of particles according to some embodiments.4

[0040] Figures 31A and 31B illustrate another embodiment of a reactor with an internal recirculation of particles and return of catalyst with carbon according to some embodiments.

[0041] Figure 32 shows experimental data in support of the invention as detailed herein.

[0042] Figure 33 shows experimental data in support of the invention as detailed herein.

[0043] Figure 34 shows photographs of ceramic monoliths for use as distributors.

[0044] Figure 35 shows schematically a process configuration for production of hydrogen, solid carbon, and chemicals using hydrogen combustion to decompose the hydrocarbon.

[0045] Figures 36A and 36B show experimental data in support of the invention as detailed herein.

[0046] Figure 37 shows experimental data in support of the invention as detailed herein.

[0047] Figure 38 shows experimental data in support of the invention as detailed herein.

[0048] Figures 39A and 39B show experimental data in support of the invention as detailed herein.

[0049] Figure 40 shows experimental data in support of the invention as detailed herein.

[0050] Figure 41 shows experimental data in support of the invention as detailed herein.

[0051] Figure 42 shows experimental data in support of the invention as detailed herein.

[0052] Figure 43 shows experimental data in support of the invention as detailed herein.

[0053] Figure 44 shows experimental data in support of the invention as detailed herein.

[0054] Figure 45 shows experimental data in support of the invention as detailed herein.

[0055] Figures 46A-46C show experimental data in support of the invention as detailed herein.

[0056] Figures 47A-47B show experimental data in support of the invention as detailed herein.

[0057] Figures 48A-48B shows experimental data in support of the invention as detailed herein.

[0058] Figures 49A-49D show experimental data in support of the invention as detailed herein.5

[0059] Figures 50A-50C show experimental data in support of the invention as detailed herein.

[0060] Figure 51 shows experimental data in support of the invention as detailed herein.

[0061] Figure 52A and 52B illustrate an experimental setup to provide data on internal recirculation of particles according to some embodiments. DETAILED DESCRIPTION

[0062] The reversible endothermic reaction for the decomposition of hydrocarbons requires heat addition which can be provided by combustion of a fraction of the hydrogen product or from alternative heat sources as detailed below. Without a catalyst, the reaction requires extremely high temperatures to achieve acceptable reaction rates and may produce a sooty undesirable carbon product. In the presence of a transition metal catalyst, the temperature can be reduced and a graphitic carbon product produced. The reversible reaction is inhibited at high pressure. An improved process will create a balance between low hydrocarbon conversion at lower pressure and / or lower temperature and higher conversion at higher pressure and / or higher temperature.

[0063] To facilitate the reaction at lower temperatures, catalysts have been used including transition metals (e.g., Fe, Ni, Co, etc.). Certain carbons have also been shown to be a moderately active catalyst for pyrolysis. Catalytic pyrolysis of methane has been observed at temperatures as low as 600 °C on transition metals, which are the most active pyrolysis catalysts. In general, solid catalysts used for pyrolysis in fixed bed reactors rapidly deactivate as the solid carbon is deposited on the catalyst surface, thereby blocking access to the catalytic surface sites by the hydrocarbon. Further, the carbon builds up within a fixed tubular bed and clogs the reactor. Provided sufficient hydrogen can be produced prior to catalyst deactivation, it is possible to make use of catalysts in a process that either regenerates the catalyst activity or disposes of the catalyst together with the solid carbon. n(CH2m)^Active Catalyst ^^^ nCsolid^ n*mH2^ Inactive Catalyst6

[0064] If the catalyst can be replaced, recovered, or regenerated at a very low cost and the hydrogen yield per unit mass of catalyst is sufficiently high, then such a process can be cost-effective. Previously, the carbon (coke) has been removed by oxidation to regenerate the catalyst which produces unwanted carbon dioxide. Iron is found to have sufficiently low-cost and high hydrogen yields to be of potential use in the pyrolysis of hydrocarbons in commercial applications and is a preferred metal.

[0065] Fluidized bed reactors (FBR) for methane pyrolysis using iron or other iron- group catalysts have been previously investigated and disclosed. Prior work with iron in FBR for pyrolysis using Fe and Fe supported on alumina was shown to be highly active at 1000 ℃, however, rapid deactivation was observed. Torres et al. investigated methane decomposition in fluidized bed reactor with Fe / Al2O3 in the temperature range of 700- 900 ℃ and space velocities between 3-6 L / gcat.h and achieved 40% conversion up to 6 h with 4.8 grams of carbon per gram of catalyst. They also observed that conversion increases by increasing temperature and lowering space velocity. Additionally, the deposited carbon was in the form of nanofibers and multiwall nanotubes. Similar work in a fluidized bed at 850 ℃ with spray coatings of iron oxide on alumina showed high initial activities with decreasing activity as the C:Fe mole ratio increased beyond 2. Similarly, iron oxide coated zirconia was used in a fluid bed at approximately 800 ℃ showed high initial activity with a rapid deactivation. Qian et al. proposed a fluidized bed with 40% Fe on Alumina at 750 ℃ was reported to have a conversion of over 75% for an hour and achieved 11 gms C per gm of catalyst. The same research work also explored the iron ore as a catalyst in fluidized bed reactor for methane pyrolysis and achieved 60% methane conversion up to 5 h 850 ℃, 5 bar and 3.75 L / gcat.h. Further, they explored the iron concentrated powder, fine / coarse ash and steel slag, volcanic mud powder as a catalyst for methane pyrolysis. Among all these, iron concentrated powder was found to be best suitable candidate for methane pyrolysis and achieved 4.7 gms C per gm of catalysts at 3 L / gcat.h space velocity and 900 ℃. In no prior work was a practical and commercially economical means of heat addition to the fluidized bed reactor disclosed that would provide the necessary heat for the endothermic reaction and no7    specific or practical means for management of the low-density carbon product disclosed.

[0066] The processes, reactors, and methods disclosed herein demonstrate how molecular hydrogen production from the decomposition of hydrocarbon feedstocks can be facilitated by the novel combination of catalytic materials for methane decomposition and specific reactor configurations with novel means of heat management. A novel aspect as disclosed herein makes used of the physical interactions between and different physical properties of an inert solid and catalytic solids whose properties change in time which are made possible by unique reactor configurations that can provide for high yields of hydrogen and carbon per unit mass of catalyst. Specific beneficial use is made of the significant density and gas fluidization differences between the inert solid and the carbon which is deposited adherent to the nanometer scale catalyst allows for the different physical behavior of the catalyst and inert solids used for heat transfer to be exploited to achieve high efficiency in production of hydrogen from hydrocarbons.

[0067] To maximize the efficiency of a hydrocarbon decomposition (pyrolysis) process it is necessary to: i) achieve a high hydrocarbon reaction rate and produce a desired solid carbon product (use a catalyst), ii) efficiently add heat to a high temperature reactor and recover that heat, iii) efficiently remove solid carbon from the reactor, vi) improve or maximize the carbon / catalyst ratio. Herein novel systems and methods are described which provide for these significant process improvements for improved or maximum efficiency.

[0068] Disclosed herein are novel processes, reactors, and catalysts described for the conversion of hydrocarbons (e.g., fossil based, etc.) to solid carbon and chemical products without the co-production of carbon dioxide. The first reaction step for the fossil hydrocarbons is decomposition to produce solid carbon and hydrogen with unique reactor configurations disclosed that provide for solid carbon management and heat exchange. Alternative configurations are disclosed which allow for heat addition within the reaction environment and management of the modified reaction products which are co-produced with solid carbon and hydrogen.

[0069] The processes and embodiments described herein are also related to integrated8    processes for the conversion of a chemical feedstocks comprised primarily of hydrocarbons to products comprised primarily of solid carbon and other hydrogen containing chemical products including molecular hydrogen without the net production of carbon dioxide.

[0070] Features of the integrated process 100 are shown schematically in Figure 1 and comprise the following process steps: 1) the preparation and preheating of one or more feedstocks primarily consisting of hydrocarbons in a heat exchanger 102, 2) the introduction of the feedstocks into a chemical reactor 104 whereby the primary reaction is the conversion of a majority of the hydrocarbon feedstock in the first reactor on a catalyst to produce products including solid carbon, for example deposited on the catalyst, and gaseous products including hydrogen, 3) the separation of gas phase products from the solid products consisting of solid carbon and carbon affixed to the catalyst in a separator 106, 4) the removal of a fraction of the solid carbon affixed to the catalyst before return of the remaining solids to the reactor, 5) the addition of fresh catalyst or a catalyst precursor to the reactor, 6) the provision of heat to the reactor either externally or internally, 7) the cooling and processing of the gas phase products in a separator and production section 110 to final chemical products including hydrogen.

[0071] In some embodiments of a system 200 shown schematically in Figure 2, the heat addition to the reactor can be accomplished by the circulation of an inert solid using a high velocity gas which is heated by one of a number of methods such as electrical heating (e.g., using electricity including renewable electricity, etc.) of a gas (including but not limited to H2, N2, CO2, Ar, etc.), combustion of hydrogen, and / or combustion of a hydrocarbon. The circulating inert can be specifically selected to be denser and larger than the solid carbon and carbon / catalyst particulates, can move counter current to the reacting gases and circulating solid carbon, and can be minimally reactive with the hydrocarbon. The downward circulation of the inert and removal at the bottom of the reactor allows for direct contact and preheating of the reactant gas as the inert solid moves downward countercurrent to the reactive gases to exit for recirculation in the lower section of the reactor. This unique configuration produces no carbon oxides when9    electrical or hydrogen combustion are used for heating in the side loop 202. When hydrocarbon combustion is used, the carbon oxides are processed as described below in other embodiments. A unique and novel feature of the circulating inert solid heating is the ability to flexibly make use of the most cost-effective energy sources of heat. For example, if low-cost renewable electricity is available for several hours per day the inert heat source can rely on electrically heated hydrogen gas to circulate the solids. When the price of electricity rises at different times of the day, oxygen can be introduced into the hydrogen stream to combust the hydrogen maintaining a carbon oxide free process. Further flexibility is possible by combustion of a hydrocarbon during other periods when cost-structures or use elsewhere (see below) of the carbon oxides produced by combustion is most economical.

[0072] In some embodiments, the heat addition to the reactor is accomplished by addition of reactants that will undergo heat generating reactions within the reactor providing the heat needed to produce carbon and hydrogen from the hydrocarbon reactants reacting endothermically on the catalyst within the reactor – autothermal pyrolysis (e.g., as shown schematically in Figures 11-16 and described in more detail herein).

[0073] In some embodiments, oxygen and a fraction of the hydrogen product can be fed together and combusted to produce a stream of high temperature steam with the heat produced used for the endothermic conversion of the hydrocarbons to solid carbon and hydrogen on the catalyst. The short residence time and relatively slow kinetics of the steam reactions prevents the steam from reacting significantly. This novel approach relies on the relatively fast chemical kinetics of the desired reactions producing steam and the catalytic pyrolysis reaction to avoid the undesirable carbon oxides produced by the reactions of steam. Although minimized or reduced, any carbon oxides produced when generating the heat are converted to chemical products as described herein. In another preferred embodiment, oxygen and a hydrogen halide (e.g. HCl or HBr) are combusted exothermically within the reactor to produce hot steam and the corresponding halogen (Cl2 or Br2) which in turn activates and transforms the hydrocarbons with or without a10    catalyst into solid carbon, hydrogen, and the hydrogen halide.

[0074] To summarize, the systems and methods described and demonstrated by examples demonstrate a versatile integrated process for the conversion of a hydrocarbon feedstock into products comprised primarily of solid carbon and hydrogen with the following options for providing the heat required for the endothermic primary reaction of hydrocarbon to solid carbon and hydrogen: 1) A circulating inert solid that is heated separately by one, or a combination of, the following; i) electrically heated gas, ii) combustion of hydrogen, iii) combustion of hydrocarbons, where the inert solid circulates countercurrent to the catalyst / carbon solid circulation. This configuration allows maximum flexibility of the process to take advantage of local prices, regulations, and other factors to optimize economic performance. 2) The exothermic combustion of hydrogen with oxygen within the reactor producing hot steam which provides the reaction heat for the hydrocarbon decomposition. The reactor is a kinetic design that relies on the rapid desired kinetics of hydrocarbon pyrolysis on a metal catalyst and hydrogen combustion and the relatively slow kinetics of steam reacting to form carbon oxides and hydrogen. 3) The exothermic oxidation of a hydrogen halide with oxygen producing within the reactor hot steam and a halogen which in turn activates the hydrocarbon facilitating its conversion to solid carbon, hydrogen, and regenerating the hydrogen halide. Specific reactor configurations are disclosed enabling the above process features.

[0075] Some embodiments, which we have demonstrated in the Examples, make use of commercially available iron ore as the metal catalyst precursor which is added directly to the fluidized bed and under the combined influence of fluidized bed and chemical environment transforms larger micron scale ore particulates into active iron / iron carbide catalysts. Another novel embodiment in the integrated process is the utilization of atomic11    metals in the form of metal carbonyls or metal salts that provide a means of producing solid carbon in the form of valuable carbon nanotubes and fibrous structures. These atomic metal sources can be produced on-site within the process boundaries allowing recovery and reuse of the metal catalyst. It is found that the chemical environment in which the metal catalyst precursor evolves is extremely important in determining the carbon-to-metal ratio in the final carbon product and the physical-chemical form of the carbon. We disclose the use of a promoter or modifying agent including but not limited to sulfur, chlorine, oxygen, carbon dioxide, carbon disulfide, methane thiol, and thiophene to either pre-treat outside the process or added to the reactor subsystem to modify the carbon isoforms developed on the iron catalyst.

[0076] The embodiments disclosed herein make possible an improved or optimized processes for conversion of hydrocarbons to solid carbon and hydrogen without net production of carbon oxides which might leave the process. The basic chemical transformations of hydrocarbon containing feedstocks are shown schematically in Figure 1, the energy requiring (endothermic) decomposition (pyrolysis) of the feedstock is the primary chemical reaction. ^(CH2m)^^^ Csolid ^mH2

[0077] Preferably, the reaction is catalyzed by a transition metal containing catalyst (e.g., iron, etc.) in a fluidized bed reactor whereby the fluidized solid catalyst accumulates carbon and is fluidized in a turbulent or fast fluidization regime (e.g., as shown in the flow regimes in Figure 10) whereby there is circulation of the solid carbon and catalyst from the bottom to the top of the reactor and a facility to return the solids to the lower section of the reactor. In some embodiments, for example as shown in Figures 2, and Figures 5-9, a separate countercurrent movement of inert solids is facilitated whereby the heat addition to the reactor occurs through the heated inert solids using hydrogen combustion (e.g., as shown in Figure 3), hydrocarbon combustion (e.g., as shown in Figure 4), or the electrical heating of an inert gas or hydrogen (e.g., as shown in Figure 5). Figure 3 schematically shows the heat provided by combustion of a fraction of the product hydrogen 302, and Figure 4 shows a process option where a hydrocarbon is12    oxidized to provide the reaction heat. The oxidant in stream 402 is illustrated as only oxygen, O2, however, the oxygen may be included in an air stream with nitrogen or purified partially or completely with nitrogen removal provided elsewhere. The hydrocarbon oxidation produces undesirable carbon oxide intermediate products; however, a novel aspect of the invention is the integrated use of a fraction of the hydrogen product into a useful chemical product that consumes the carbon oxide. Preferred chemical products include methanol and other alcohols as well as olefins and acetic acid. Figure 3 illustrates the heating of the circulating inert material heated by combustion of hydrogen without carbon oxides, or, Figure 4, if hydrocarbons are combusted, how the carbon oxides produced can be combined with a fraction of the product hydrogen to produce chemicals and water.

[0078] Figures 5 to 8 show schematic configurations of fluidized bed reactors whereby the combustion heat is introduced into a catalyst containing reactor by use of a circulating inert material that segregates from the active catalyst on which carbon is produced by virtue of the different physical properties. A key and novel aspect of the disclosed systems and methods is the utilization of dual fluidized beds whereby the circulation of the heat providing inert solid is one loop 502 circulating countercurrent to the gas phase reactants and products and a second loop 504 circulates the carbon affixed to the solid catalyst.

[0079] Further, when the fluidized bed is operated in regimes of high gas velocities (turbulent and fast fluidization as shown in Figure 10) a second loop returns the fluidized solids to the reactor to control the average solid residence time within the reactor.

[0080] In another embodiment, the use of heat transfer to the solid carbon / catalyst returned to the reactor can be used in the absence of the circulation of inerts as shown in Figure 9. Because the solid carbon and catalysts are relatively inert, they can be heated by high temperature internal heating coils where the heat is provided by electricity or combustion. The heated solids are returned to the reactor as part of the primary solids circulation to provide the reaction endotherm. To ensure minimal reaction with the heating coils the loop seal gas can be hydrogen.13

[0081] A simple process with few components can be created by eliminating the need to transfer heat in an environment separate from the main chemical reactor. In some embodiments, the heat required for the endothermic dehydrogenation reaction is generated within the primary reaction environment. Rather than have a physically separate heat generating oxidation step and a circulating solid, a major innovation described herein is the introduction of the oxidation reaction into the same reactor vessel as the hydrocarbon decomposition to form carbon and hydrogen. This eliminates the need for the reaction heat to be provided by an externally circulating inert with the oxidation within the reactor now providing some or all of the reaction heat. Combinations of circulating inerts and internal heating might also be used.

[0082] The autothermal process for hydrocarbon pyrolysis can combust only hydrogen to directly produce superheated steam. Further, since for carbon oxide free pyrolysis produces only hydrogen, carbon, and if combustion is used steam as the desired final products, the pyrolysis reactor can establish a reaction environment whereby the primary reactor feed is a hydrocarbon with sufficient oxygen to provide the reaction enthalpy and produce as primary products only hydrogen, carbon, and steam. For methane pyrolysis, the autothermal process can operate at approximately 900-1000 C and can have a hydrogen yield of approximately 1.5 moles per mole of methane feed, and can consume only a fraction of the hydrogen from pyrolysis, n~ 0.25-0.35. Ideal: CH 4 + nO 2 ^^^ C + 2(1-n)H 2 + 2nH 2 O ^ H 950C ~ 0

[0083] This is not the equilibrium stoichiometry which at approximately 900-1000 °C would result in significant carbon oxide generation. An important innovation in the reactor configurations described is the operation in a kinetically limited and non- equilibrium reaction regime. If equilibrium is achieved too little heat is available and carbon oxides are produced. Equilibrium : CH 4 + 0.25O 2 ^ ^^^^ 0.5C + 2H 2 + 0.5CO

[0084] The reactor relies on the relatively rapid kinetics of hydrogen combustion and catalytic pyrolysis and the relatively slow reactions of steam which produces undesirable carbon oxides. A unique and novel aspect as disclosed herein is the use of iron-group14    catalysts which produce graphitic carbon which has the lowest reactivity with steam and, in some embodiments, introducing an excess of hydrogen with the oxygen to inhibit reactions with steam. If iron is present in the catalyst it is desirable to minimize any oxidation. Fast: CH 4^ F^e^C + 2H 2aH +aFAST2 O 2^^^^aH O2242 3H 2C + H 2 O ^^^^^CO + H 2Fe + H 2 O ^^^^^FeO + H 2

[0085] A key feature of the use of hot steam for heating is that all side reactions producing CO also produce extra hydrogen which allows facile management of the carbon oxides as described below.

[0086] Figures 11-16 show schematically examples of the many configurations of such a process implementation. In Figure 13, oxygen in stream 1302 is shown injected directly into the hydrogen rich zone of the reactor 1034. A preferred implementation is the combustion of hydrogen with oxygen producing steam, as shown in Figure 12. Assuming the reaction environment is approximately 950 °C, the heat from combustion is: H+1 O^kJ^2 2 2 ^^^ H 2 O ^ H 950 C ~ ^ 249 ^^ mole ^^

[0087] For a methane feed at 500 °C, theheating and dehydrogenation enthalpy at 950 °C is approximately 124 kJ / mole methane. Thus, ideally, only a small fraction of the hydrogen product need be consumed to provide the heat. It is anticipated that at many reaction conditions some reaction of the high temperature steam may occur with the carbon and / or hydrocarbons. These can be minimized by control of temperature, gas residence time, and pressure. However, a feature of the present integrated process is that any carbon oxides that are made as byproducts will be associated with a proportionate15    increase in hydrogen generation and thus hydrogen will be available to abate all the CO byproducts. Any resulting carbon oxides can be managed as described below. Hydrogen combustion is the preferred means of adding heat to the reactor as the least oxygen is required and carbon oxide generation avoided. [00 tion, insome embodiments, the hydrogen-oxygen combustion is distributed throughout the reactor environment to minimize the local partial pressure of steam. The specific hydrodynamic design and gas flow fields are configured to allow the introduction of extremely high temperature steam from hydrogen combustion into the reactor internally to maximally transfer heat by high rate direct contact heat transfer with minimal contact with carbon or hydrocarbons until the steam has been cooled sufficiently to minimize reactivity. Figures 14A and 14B show schematically how with increasing distance from the methane inlet the hydrogen partial pressure increases and methane decreased. Steam introduced in the environment with a relatively greater hydrogen partial pressure will reduce the byproduct carbon oxides. Side feed nozzle / burners may be used or internal distributed nozzles where the hydrogen and oxygen are mixed and combusted may be utilized with varying locations depending on the heat requirements, Figures 15 and 16. The nozzle assembly may be integrated with other reactor internals (Figure 14).

[0089] Depending on the specific reactor feed inlet temperatures, the required hydrogen combustion may be varied. Fortunately, the relatively small increase in steam passing through the process will have a minor effect on the overall process even with relatively cool reactor feeds.16   Ideal Optimistic Preheat: CH (500 C) + 0.3O (200 C) + 0.6H (800 C) ^^^^ C + 2H + 0.6H O ^ H ~ ^ 15 kJ / moleIdeal Pessimistic Preheat: CH (450 C) + 0.3O (100 C) + 0.6H (300 C) ^^^^ C + 2H + 0.6H O ^ H ~ ^ 2 kJ / molethe need for all the reaction heat to be provided from an external source is accomplished by combining the exothermic reaction of a hydrogen halide, HX, with oxygen producing a halogen, X2, and steam with the hydrocarbon decomposition reaction. The preferred halogens, X, are chlorine and bromine both of which are known “flame retardants” which inhibit carbon oxide formation. These halogens react immediately with the hydrocarbons and significantly increase the rate of pyrolysis. A novel element includes the recognition that their flame retardant properties will limit the production of carbon oxides and favor the production of “char” (solid carbon) with is the desired product. The process is shown schematically in Figure 17. Although the use of halogens in chemical processes has associated materials of construction considerations, there are many solutions to these problems known to those skilled in the art - as is illustrated in Figure 18 which shows photographs of HCl oxidation reactors from small lab scale units to full size commercial fluidized beds. Figure 19 shows schematically one of many circulating autothermal fluidized bed configurations possible to implement the hydrogen halide – coupled pyrolysis process. In the halogen containing process a metal catalyst may or may not be utilized. In some embodiments, a transition metal such as iron can be used as the catalyst for pyrolysis.

[0091] In many of the process options described herein, a catalyst is used and in real applications a low-cost catalyst precursor will be used and provided to the reactor. Typically, an oxidized metal evolves in a hydrocarbon containing reducing environment into nanoparticulate catalysts containing metal on which the hydrocarbon decomposition occurs resulting in the deposition of carbon on the catalyst. Figure 20 shows schematically the process for a preferred iron-based catalyst derived from iron ore. The iron oxide ore is reduced to iron and the particle fragments into nanoparticles containing iron and carbon. As the thickness of the carbon layer increases the activity of the catalyst decreases until it is fully encapsulated and the hydrocarbon can no longer reach the17    surface to react. It is desirable to have the largest possible mass of carbon per unit mass of catalyst to maximize the process efficiency. Methods and processes for achieving this objective are described herein.

[0092] Major improvements and innovations disclosed herein over prior art are specific reactor configurations allowing for heat addition to the reaction environment that take advantage of the physical differences between the intermixing and separation of physically different components within the catalytic reactor and new ways and means of providing the metal catalyst.

[0093] Recently, a method and reactor system have been discovered to make use of a stratified fluid bed reactor to separate low density carbon and catalyst to upper regions of the fluidized bed reactor. Major improvements and innovations disclosed herein are specific reactor configurations allowing for heat addition to the reaction environment that take advantage of the physical differences between the intermixing and separation of physically different components within the catalytic reactor and novel means of providing the metal catalyst. The use of a stratified fluidized bed reactor can allow the relatively dense and coarse inert solids (e.g., sand, etc.) to segregate separately without the carbon and / or catalyst to the bottom of the reactor where it can be removed, heated, and circulated back to the top zone of the reactor to provide the reaction heat, as shown in Figures 5-9.

[0094] The solid carbon produced by the catalytic pyrolysis process described herein produces particulates composed of aggregates of the metal containing nanoparticle catalyst between about 3 nanometers (nm) and about 100 nm in size encapsulated by between 10 nm and 400 nm of carbon. The aggregates are typically 5-500 microns in size and of low density. The particles are fluidized at relatively low superficial gas velocities and their terminal velocities are also relatively low (< 0.1 m / s). An embodiment of the process can include the use of natural gas (comprised of mostly methane) pyrolysis on iron containing catalysts, where for commercial operation of a 100 kta reactor, methane flowrates within the reactor can be over 10 m3 / s at 950 °C and 10 bar. For any acceptable reactor diameters, the superficial gas velocity will be high such18    that the operating regime of the bed will be so called turbulent or fast fluidization, Figure 8, resulting in the solid fraction fluidized within the reactor to decrease with height above the sand from a maximum of approximately 20-40% at the interface with the sand. In this fluidization regime it will be solid particulates containing carbon and catalyst with the hydrogen product gas at the top of the reactor. The carbon-to-catalyst ratios of the particles will be varied and control over the removal from the bed is required.

[0095] In some embodiments as shown schematically in Figures 5-8 two separate circulation streams are created by the novel use of a stratified fluidized bed reactor containing a relatively dense inert material, preferably sand, and a low-density solid carbon product growing within the reactor on a metal containing catalyst (preferably iron). The reactor and most solid transfer lines are preferably ceramic insulator lined metallic pressure vessels and piping operated at a pressure between 1 bar and 30 bar and a temperature of between 750 °C and 1000 °C. In some aspects, the reactor can have a cold wall design whereby the metallic pressure boundary is maintained at a much lower temperature than the materials in contact with the ceramic internal walls. The relatively dense inert can be introduced in an upper portion (e.g., within the upper 30% of the reactor height) and / or near the top of the reactor and moves countercurrent to the upward moving gas heating the reaction volume and, by virtue of its density and size, segregates to the bottom of the reactor vessel where it may be somewhat cooled by the entering reactant gas and removed near the bottom of the reactor through a loop seal or similar structure to control the solid and gas flow. The inert solid is then heated in a hot high velocity gas stream and lifted above the inert inlet to the reactor, separated from the heating gas in a cyclone or other solid-gas separator and returned through a loop seal or other solid flow control device to the top of the reactor to provide the reaction heat for the endothermic pyrolysis reaction. The gas heating the inert may be heated using hydrocarbon or hydrogen combustion or electrical heating, as described herein.

[0096] In an embodiment as shown in Figures 5 and 6, operating in a turbulent or fast fluidization flow regime, a fraction of the carbon within the reactor will exit with the product gases and will be separated from the gases in a cyclone or similar gas-solid19    separator. At steady-state, carbon is removed from the process after separation at the same molar rate as the molar rate of methane conversion, approximately 8 moles / sec per kta of hydrogen produced. Since the carbon will contain metal containing catalyst, an equivalent mass of fresh catalyst as that removed must be added to the reactor. This can be done either in the stream of heated inert solids, or at a point below the exit stream of carbon from the carbon circulation loop.

[0097] A major challenge of handling the iron-based catalysts in a fluidized bed reactor are agglomeration and sintering of iron particles in the presence of reducing environment at elevated temperature, formation of unwanted carbon byproducts, and the separation and high density of iron particles still remain unresolved. Further, most prior work relied on first processing the iron or other metal at significant cost and fabricating specific supported catalysts to achieve activity. In order to solve these issues, the use of iron in a fluidized bed reactor can be used with specific process and design considerations. These challenges are solved by the novel use we have proposed of a high density inert solid comingled with the low-density catalyst in contact with the carbon.

[0098] In all prior art systems with metal catalysts, the hydrogen yield per unit mass of the relatively expensive catalyst has been relatively low and the opportunities for heat addition limited. The novel aspects of the invention described herein make use of, i) the cooperative interaction of inert particles which are relatively dense compared to the carbon product produced on the surface of metal-based catalysts, and / or, ii) the unique flow field and chemical interactions of the oxidant(s) in the reactive gases. These interactions allow for greater yields of hydrogen and carbon per unit mass of catalysts and the properties of the inert allow for stratification of the inert particles within the reactor and selective removal and / or heating of the inert particles. The physical interactions of the inert particles with the catalysts within the fluidized bed can physically partially reactivate the catalysts by attrition which helps to disengage the carbon from the catalyst allowing additional reaction activity and greater yields. The dual fluidized bed configuration provides ease in removal / addition of carbon and catalyst.

[0099] To increase the solids residence time within the reactor to allow increased20    carbon-catalyst ratios to be achieved and increase the contact of the circulating inert solids, internal structures can be introduced within the reactor as commonly employed in two-phase distillation columns and other applications. The novel application to hydrocarbon pyrolysis reactors is shown schematically in Figures 6 and 7 whereby down going heated inert solids move downward in the upward flowing gas and low-density particle streams and are partially retained on structures within the reactor where they can accumulate together with the catalyst particles and growing carbon. Perforations may or may not be employed on the tray-like structures 602 as shown in Figure 6, to facilitate contact and movement of the higher density inerts. Internal cyclones 702, as are well known in the field may also be employed within the reactor to avoid the external circulation of carbon as shown in Figure 7.

[0100] In the novel reactor configurations described thus far above, heat was provided to the reactor by an external heat source and circulating inert particles. In another embodiment, shown schematically in Figure 9, the reaction heat is added by preheating the externally circulating solids which are reintroduced to the lower section (e.g., a lower 30% of the reactor height) of the reactor. The heating can be via direct contact with coils heated electrically or by combustion.

[0101] In another novel embodiment shown schematically in Figure 21, use is made of the physical differences in properties of the catalyst as it evolves in size and carbon is deposited on the metal surface. In the early stages of evolution, the catalyst (and / or catalyst precursor) is relatively dense and, by use of an internal cyclone designed to circulate and return selectively larger and more dense fluidized solid materials to the reactor, the catalyst-carbon particulates are allowed to develop and increase their carbon- to-iron mass ratios until the less dense particulates are allowed by the design of the internal cyclone to leave the main reactor vessel and be removed from the exiting gas stream in an external cyclone that transfers the solids to a separate external vessel 2102. The solids accumulate in the external vessel 2102 as a relatively high void fraction packed bed. The transfer of particles to this packed bed allows the catalyst / carbon particulates to be used in the packed bed for further reactions including, but not limited to, additional21    methane conversion, conversion of carbon oxides with hydrogen to other products.

[0102] In another embodiment, shown schematically in Figure 19, the reaction heat and pyrolysis catalyst is supplied to the reaction environment by the introduction of a hydrogen halide and oxygen into the inert filled lower section of the reactor which react to a halogen and steam. The heat from the reaction is thus introduced to provide for the pyrolysis reaction heat. 1 O+ 2HX^^ o^kJ^ ^kJ^ 22 ^ X2 ^H2O ^H800C ~ ^59^^mole^ ^^140^^mole^ ^

[0103] The preferred halogens are chlorine and / or bromine which provide exothermic heats of reaction of -59 kJ / mole and -140 kJ / mole when generated from their respective hydrogen halides. The halogen then reacts with the hydrocarbon fed higher in the reactor after the hydrogen halide is reacted to produce hydrogen, carbon, and regenerates the hydrogen halide. For the ideal mole fraction of halogen is approximately, m=0.4 the reaction enthalpy is relatively small and the free energy very favorable to produce the desired carbon and hydrogen products,CH4 + 0.4X2 ^^^ C + 1.6H2 + 0.8HX ^H o800C ~ 15^ ^kJ^ ^ ^ mole^ ^47^ kJ^ ^ mole^ ^CH + 0.2O ^^^ C + 1.6H ^ 0.4H O ^H o ~ ^^kJ^ 42 2 2 800C 9^^mole^ ^The novel use of hydrogen halides as a catalyst for the partial oxidation of hydrocarbons including methane to produce carbon and hydrogen overcomes key barriers to the hydrocarbon dehydrogenation by providing the heat and creating an autothermal reaction environment thus eliminating the need for an external heat source and allowing the use of adiabatic reactors. Further, bromine and chlorine are flame retardants that inhibit the formation of carbon oxides minimizing any reactions of the oxygen containing species with the hydrocarbons. With hydrocarbons other than methane less halogen is required and greater hydrogen yields possible. The separation of the hydrogen halide from22    hydrogen can be accomplished with methods well known in the industry. In the ideal case the autothermal HX combustion compares well to autothermal hydrogen combustion. CH 4 ^ aH 2 ^a O^A^uto^therm^al H^2 co^mbu^stion^^ C ^ a H O + 2H22 2 2some or can as a metal halide, preferably FeCl3, this provides a source of a metal catalyst (e.g., Fe, etc.) to the reaction environment and the HCl generated can be reacted with oxygen to generate the reaction exotherm. With the hydrogen halide separation of the metal from the carbon can be accomplished by dissolution.

[0106] The systems and methods disclosed herein provide a means for utilization of a catalyst for methane pyrolysis and reactor systems for its use that provide for high hydrogen yields at modest temperatures with a low-cost catalyst. The invention makes use of a fluidized bed containing a mixture of catalysts, carbon, and inert particles with different densities and sizes which allow for unique stratification and segregation behavior within the fluidized reactor bed. This behavior, by design, facilitates both heat transfer to the reactor, high utilization of the catalyst, and carbon product removal.

[0107] The novel combination of an inert solid with an active catalyst makes use of the fluidized inert solid in part to minimize sintering and partially reactivate the catalyst within the fluidized bed to maximize the hydrogen yield per kg of catalyst added to the reactor. In some embodiments, heat addition can be supplied by high temperature combustion gases applied directly to the inert particles which, because of their density segregation, can be continuously removed without the presence of significant quantities of solid carbon containing the catalyst.

[0108] The process cost must include the cost of any catalyst retained in the carbon23    solid. As shown in Figure 20A, the carbon produced encapsulates and eventually deactivates the metal catalyst containing x atoms of the metal catalyst M. ^CH2n + xM ^^^ CMx ^ nH2

[0109] The carbon-to-metal atomic ratio CMR=1 / x is increased or maximized by decreasing or minimizing the amount of retained catalyst. One method of improving the CMR is to make use of the smallest possible metal containing catalytic particles. Introduction of the metal catalyst as a compound containing a single metal atom which can evolve in the fluidized bed reaction environment into a tiny metal nanoparticle is one method of achieving a high CMR. In an embodiment, iron can be introduced as iron pentacarbonyl, Fe(CO)5into the reaction environment whereby the carbonyl decomposes and the iron atoms aggregate to form nanoparticles of iron 2-10 nm in size which catalyze the hydrocarbon decomposition. Other sources include but are not limited to ferrocene, iron salts such iron chloride, iron citrate, and / or iron nitrate. The use of iron halides such as iron chloride can have the benefit is introducing a halogen into the reactor as described in more detail herein. As shown in Figures 22A-23C when atomic or nanoscale iron sources are used as the catalyst source, high carbon-to-iron ratios are achievable with carbon fiber and carbon nanotube production. A novel embodiment disclosed herein is the recovery of the metal catalyst by a reactive etching of the metal from the carbon followed by formation of a catalyst precursor. An example includes the reaction of the carbon product / metal catalyst with a halogen (preferably chlorine or bromine) to form a volatile metal halide which is recovered by condensation. The metal halide is then reacted with oxygen (possibly in air) to form the halogen and a metal oxide. For example, iron within carbon is reacted with chlorine to form volatile iron chloride which elutes from the heated carbon and condensed downstream. The iron chloride reacts with air to produce chlorine and iron oxide. Under controlled conditions the iron oxide can be produced as a nanoparticle. The chlorine is recovered for reuse as an etchant.

[0110] In another embodiment, metal carbonyl is made on-site by passing carbon monoxide over the metal containing carbon products removed from the reactor at temperatures of between 150 and 250 °C and elevated in pressure 10-100 bar. Above24    100 °C the carbonyl is a gas which can be returned to the reactor. Similarly, the metal containing carbon can be reacted with halogens such as chlorine or bromine or carbon monoxide to produce volatile metal halides or carbonyls and returned to the reactor. In some aspects, an acid can be used to react with the catalyst such as iron to form an iron salt that can be solvated or evaporated in order to be recovered and returned to the reactor. When atomic iron sources are utilized under specific conditions carbon nanotubes and / or graphitic carbon can be produced as the carbon product.

[0111] Another embodiment is a method to increase the carbon-to-metal ratio which makes use of an oxidant to disrupt the encapsulation of the metal containing carbon particle. Reference is made to Figure 20 which shows an encapsulated iron containing catalyst particle. Figure 22A illustrates how by the treatment of the catalyst particle with an oxidant prior to encapsulation, the graphitic carbon shell can be disrupted from the expansion of the oxidized metal allowing further fragmentation of the metal into smaller particles. The oxidation can be accomplished in the separate external loop of carbon (e.g., as shown in Figure 9), or alternatively by periodic switching of the gas streams entering the reactor. Preferred oxidants include H2O, CO2, O2, Sulfur or sulfur compounds, Cl2, Br2it is expected that relatively low concentrations of oxidants will typically be employed.

[0112] The purpose of the oxidant addition is to prevent the complete encapsulation of iron particle which is the main cause of the catalyst deactivation. The mild oxidant can shift the equilibrium towards the product and enhance the overall conversion of methane. It is expected that an oxidant can consume outer layer while making iron particles accessible again for reacting methane. An oxidant can either make it porous outer graphitic layer by burning off excessive carbon or biting / puncturing outer graphitic layer from sides. Now, the iron is accessible for methane reaction again which can continue carbon growth further.

[0113] As part of the reaction systems and processes disclosed herein, the resulting solid carbon formed during the reactions can generally be graphitic carbon, carbon nanotubes, or other forms of stable solid carbon. Less stable forms such as amorphous25    carbon can be more easily reacted. When carbon oxides are produced within the reactor, the carbon oxides can preferentially react with more easily reacted carbons without reacting with the graphitic carbon and carbon nanotubes. The overall process results in the reaction of any carbon oxides while producing a larger portion of the graphitic carbon and carbon nanotubes having the amorphous carbon removed.

[0114] Several embodiments described above include the maximization of C / Catalyst yield by use of oxygen to provide heat or periodically to delay encapsulation and deactivation of the active catalyst particles. Also disclosed herein is a novel process option whereby oxygen is continuously supplied to the reactor containing the metal containing catalyst and co-producing carbon, hydrogen, and carbon monoxide (or carbon dioxide). A preferred hydrocarbon to utilize is methane.

[0115] In preferred embodiments the reaction is performed at temperatures between 750 and 1000 °C and pressures between 1 and 50 bar. In the presence of a catalyst containing a transition metal the reaction will result in formation of metal carbides and deposit carbon on the metal particles as described above. As the mole ratio of oxygen is increased the reaction becomes decreasingly endothermic. For methane, as the oxygen content increases to approximately 0.2-0.4 the reaction at approximately 900 °C requires little to no external energy input. In existing industrial processes methane partial oxidation has been previously used, however, carbon has been an undesired product, whereas in the disclosed process production of hydrogen without carbon dioxide is desired and the conditions and reactors disclosed are specifically suited to produce products without carbon dioxide and to intentionally produce solid carbon on the catalyst.

[0116] In a typical pyrolysis process conducted in a fluidized bed reactor, heat must be added to maintain a temperature of approximately 950 °C where graphitic carbon is produced on a metallic catalyst (preferably iron) to a carbon to iron ratio of approximately 7 or 8. Heat addition can be either through combustion in air of hydrogen or using electrical heating in the external loop or internal autothermal use of HX or hydrogen. With heat generation within the reactor from hydrogen halides or hydrogen combustion generating steam carbon oxides will likely be produced in small quantities, predominately26    CO. CH^ E^lect^rical 4 ^^C + 2H 2CH ExtermalH2C4^^^^^omb^usti^on^C + 2H 2in exothermic low temperature reactions to yield truly direct emission free hydrogen as described below.

[0118] Fundamentally, the primary step in any pyrolysis process will consume heat. Only pyrolysis can yield in one step carbon dioxide free hydrogen when hydrogen combustion or CO2-free electricity are used for heat. When hydrocarbon combustion is utilized for the external circulating inert or steam is generated internally, then carbon oxides will likely be produced. Assuming oxygen is added such that the processes are thermodynamically isoergic at approximately 950 °C the process will produce in addition to carbon and hydrogen, steam and small quantities of carbon oxides. A key feature of the use of hot steam for heating – all side reactions producing CO also produce extra hydrogen which allows facile management of the carbon oxides.

[0119] In any chemical process producing intermediate mixtures of carbon oxides and hydrogen that seeks to eliminate carbon dioxide generation from the overall process, there are several options for managing the mixed streams to eliminate COx. An example potential pathway is to produce methanol where the oxygen goes into the methanol. CO + 2H ^^kJ 2^ CH3OH ^H = - 128The reaction produces heat which might be used elsewhere. CO2 can be similarly managed either through the reverse water gas shift reaction with management of CO or27    directly by conversion to carbon or methanol, kJ CO2+ H2 ^ R^WG^S ^ CO + H2O ^H = 41mole

[0120] scales and has anextremely low

[0121] Another CO2-free use of the carbon oxide which would consume a portion of the hydrogen product would be the production of hydrocarbon chemicals such as acetic acid or ethylene.2CO + 2H 2^^^CH 3 COOH1 O heating from hydrogen combustion the carbonoxides can be readily used for producing chemicals such as methanol resulting in minor H2 yield losses and a valuable co-product, methanol. The overall process remains CO2- free.

[0123] The disclosed integration of pyrolysis with chemical production from the carbon oxides provides a significant increase in the process economic potential.

[0124] In the novel integration of hydrogen combustion within the same vessel as pyrolysis providing the endothermic energy needed by pyrolysis, the reactor system is significantly simplified. Depending on the temperature and other conditions the combustion reaction can be performed with or without a catalyst. In one preferred embodiment shown schematically in Figures 15 and 28, a preheated mixture of hydrocarbons and separately pre-heated oxygen and hydrogen streams are contacted through a ceramic monolith 2802 (Figure 34).

[0125] The underlying phenomenon of the hydrocarbon reaction occurring on inert versus metal surfaces such as iron is different and distinguishable. Figure 23C shows the carbon produced have different attributes and morphologies. Carbon produced on iron surface is graphitic carbon since carbon produced on inert is amorphous. Figure 23C28    upper left TEM image shows a disordered carbon produced on sand while a graphitic carbon is produced on iron, similar observation is also received through Raman spectra which exhibit broad D and G peaks.

[0126] In some aspects, the processes described herein can be used for pyrolysis reactions. Pyrolysis of hydrocarbon on the microscopic iron containing precursor such as iron ore, “Pig” iron or iron, which undergoes several steps of reduction, fragmentation, carbon growth and deactivation, as shown in Figure 24. The large iron precursor is first reduced to metallic iron and afterwards these iron particles fragmented into tiny particles and takes part in continuous carbon growth mechanism before deactivation. It is possible to detach the carbon from the metal surface through addition of an oxidant or enhancer. Afterwards, separated metal particles are available for carbon growth.

[0127] One approach is to perform methane pyrolysis in counter current circulating fluidized bed reactor to provide efficient heat transfer, maintaining high C:Fe ratios and stable bed operation, as shown in Figure 25. A hydrocarbon such as methane flows from the bottom. Fresh iron particles can be added from the top. Due to difference in size and density of particles, sand, iron and iron carbide can be stratified in the reactor (e.g., forming different zones over time) which results in easy separation and circulation of particles. Sand particles would be in bottom zone all the time and freshly added iron in middle zone and carbon growth will occur in top zone where methane is limiting reactant due to excess presence of hydrogen. The proposed design may comprise a riser and a separate reacting tube with possibility of continuous addition of sand and iron and their subsequent removal.

[0128] The evolution of phases is determined through XRD. Figure 26A shows a XRD pattern with different iron precursor and their weight ratios, and Figures 26B-26D show images of the corresponding iron precursors with carbon. In the case of iron oxide, it is reduced to FeO and Fe while heating to reaction temperature (during preconditioning) and within 10 mins all the iron oxide is almost completely reduced to Fe and peak for iron carbide is start appearing. After 230 mins, XRD shows that the catalyst sample contains a very low amount of iron in sample (less than 5%) and most of the iron is in the29    form of iron carbide which is encapsulated and a high intensity peak corresponding to graphitic carbon. On the other hand, iron directly participates in fragmentation and carbon growth mechanism. However, the more carbon is formed when 10 wt.% Fe was used as compared to 20 wt.% Fe because C / Fe ratio was higher in the case of 10 wt.% Fe as compared to 20 wt.% Fe. All type of precursor formed graphitic form of carbon.

[0129] Particle size of the iron oxide changed over time and some carbon growth in observed in the form of fiber after 230 minutes, as shown in Figure 20. Initially, particles are of 17 ^^m and there was not much change in particle size we started the reaction and within 10 minutes of reaction particle size was reduced to 500 nm and there after slow change in particles. Particles were of 200 nm after 120 min and 210 nm after end of reaction. Particles size changed due to reduction, fragmentation, carbon growth and particle encapsulation with carbon.

[0130] In another preferred embodiment we make use of channeled ceramic monoliths, Figure 34, to serve as gas distributors and for separation of the heat generating hydrogen combustion from the hydrocarbon feed. Insulating ceramic monoliths, as shown in Figure 34, can be fabricated from a number of low-cost and stable ceramics including alumina, zirconia, silica, and mixtures of ceramics. The small internal channels can carry gases to be introduced into the reactor at the base of a solid bed. A preferred configuration is shown schematically in Figure 28 whereby one or more tubular sections of smaller dimensions and interspersed with the distributors of the reactant gases is shown schematically in Figure 28. A hydrocarbon feedstock, preferably methane containing is introduced into a reaction vessel in proximity but not in direct contact with the steam exits.

[0131] Figure 29 illustrates another novel embodiment of the autothermal reactor whereby an internal circulation of inert solid (e.g., sand) of greater density and size than the catalyst and carbon is established by an internal narrow riser channel of inerts heated and lifted by combustion of hydrogen and oxygen. The heated sand is lifted up into the main reactor body carrying the combustion heat with the solids and steam into a higher reactor zone where the hydrogen concentration is higher and the solids and steam have30    had time to transfer heat to minimize side reactions. The dense inert solids fall back down to the lower section of the reactor and are accumulated into the region around the hydrogen combustion nozzle. An annular distributor is used to introduce the hydrocarbon at the outer wall of the reactor where it rises and is heated by the inert prior to entering the upper reaction zone.

[0132] Figure 30A illustrates how the externally heated and circulated inert solids can be, additionally or alternatively, circulated internally, which significantly increases the heat transfer efficiency and overall energy integration. The gases used to heat the inert solids (including but not limited to combustion gases, inert gases heated electrically, H2, O2, hydrocarbon combustion, etc.) can be introduced separately from the hydrocarbons into a particulate riser, and caused by design of the pressures and depth of the solid bed to entrain, heat, and transport the inert solids to the top of the reactor above the particulate bed, whereby they can be reintroduced to the particulate bed within the reactor to provide the heat for further reactions. As shown in Figure 30B, the heating gases can be introduced within the riser entrance, which may not be sealed around heating gas inlet to allow the particulates, including the catalyst and inert particulates, to be entrained into the riser with the heating gases. An optional separate can be present at an upper end of the riser within the reactor to separate the heating gases from the solids (e.g., the inert solids), with the heating gases leaving the reactor and the solids returning to the particulate bed.

[0133] The hydrocarbons in the feed stream can be introduced above the heating gases and riser entrance, and by pressure balanced flow, move only or substantially upwards through the catalysts section of the reactor. The hydrocarbon feed can be spatially separated from the riser entrance within the reactor. This spatial separation within the reactor of the heated gases from the fresh hydrocarbon feed can reduce or minimize the production of byproducts.

[0134] Figure 30A illustrates the use of an separator such as an inert cyclone to return the heated solid particulates to the particulate bed in the reactor and separately remove the heating gases, because, as discussed above, the heating gases will be in generally31    relatively unreactive and the top of the reactor will contain little methane and mostly hydrogen. For simplicity and potentially greater heat transfer efficiency, the inert cyclone can be removed as shown in Figure 31A, and the solids and heating gases can be reintroduced above the particulate bed within the reactor. Further simplification can be made to the system by eliminating the external carbon loop and instead relying on internal exit cyclones and / or solid overflow taps from the reactor to remove carbon and catalyst under steady-state conditions and introduce new catalyst as shown in Figure 31B. Integrated Process for CO2-free Conversion of Hydrocarbons To Chemicals and Hydrogen

[0135] An embodiment of the novel integrated process is shown schematically in Figure 35. A hydrocarbon feedstock, preferably methane is introduced into a reaction vessel separately from a feed of oxygen (or air containing oxygen) and hydrogen. The hydrogen and oxygen react exothermically to provide heat for the reactor in which the products of the oxygen hydrogen reaction (hot steam) together with the remaining methane are passed over a catalyst (preferably iron) whereby the methane reacts with the catalyst to produce carbon on the catalyst and hydrogen. The gas phase products leave the reactor subsystem either separately or together with a fraction of the carbon / catalyst solid and the products separated using methods well known to the industry (cyclones, pressure swing absorption, membranes, etc).

[0136] Any carbon oxides present in the product gases are combined with a fraction of the hydrogen product gas and used in one of many syngas processes known to the industry including but not limited to methanol synthesis, ethylene / propylene synthesis, acetic acid synthesis, and other syngas conversion processes which convert carbon oxides with hydrogen to chemicals without the need for heat or the production of CO2.

[0137] The carbon leaving the reactor subsystem is attached to the metal containing catalyst (preferably iron) and it is desired to recover the metal containing catalyst and return the catalyst to the reactor. The mixture of catalyst and carbon may be processed32    in a number of novel ways to recover the metal and prepare an optimal catalyst feed for the reactor. In one preferred embodiment the carbon / iron is reacted with a gas phase halogen (Br2, Cl2) at temperatures between 100 °C and 500 °C. The halogen reacts with the iron carbide to produce a volatile iron halide leaving behind the carbon and effectively separating the metal from the carbon. Gas phase or liquid phase hydrogen halides (HCl, HBr) may also be used to produce the iron halide and hydrogen gas. The metal halides may then be used directly as a catalyst precursor, or further processed by reduction (in H2) or preferably by oxidation in oxygen (or air) to produce metal oxide and recover the halogen. The metal oxide prepare in this manner can have nanostructures suitable for high C / Fe ratios. EXAMPLES

[0138] The disclosure having been generally described, the following examples are given as particular embodiments of the disclosure and to demonstrate the practice and advantages thereof. It is understood that the examples are given by way of illustration and are not intended to limit the specification or the claims in any manner. EXAMPLE 1

[0139] In a specific example, methane pyrolysis was performed in a semi-batch fluidized bed reactor. The reactor was a quartz tube with 90 cm length with tapered diameter from 1 cm at bottom and 2.5 cm at top. Approximately 12 g of sand and iron (20% Fe) was loaded in the reactor and methane was flowed through another tube at the bottom end. The bed height without any flow was around 15 cm with void fraction of 0.5. However it changed from 0.50 at room temperature to 0.56 at reaction temperature and bed length increased from 14 cm to 20 cm. The total heated length was around 60 cm. The activity of the catalyst is observed to change over time in the semi-batch fluidized bed reactor where the solids remain in the bed so that their time-dependent properties can be measured. First, bigger iron oxide particles (~17 ^^m) were reduced and fragmented into tiny particles (<500 nm) which further participate into carbon growth and ultimately33    deactivate, as shown Figure 20. The deactivation is probably due to the encapsulation of iron particle by non-porous graphitic carbon layers and iron surface is not accessible for the methane to react. Once completely encapsulated and deactivated, further decomposition of methane could results from the surface irregularities which appears to form non-graphitic carbon. The above 85% conversion was achieved at 950 ℃ and 0.73 residence time. The purpose of the oxidant addition is to prevent the complete encapsulation of iron particle which is the main cause of the catalyst deactivation. The mild oxidant can shift the equilibrium towards the product and enhance the overall conversion of methane. It is expected that an oxidant can consume outer layer while making iron particles accessible again for reacting methane. An oxidant can react and form a porous outer graphitic layer by burning off a fraction of the excessive carbon or by puncturing the outer graphitic layer from the sides. Now, the iron is accessible for methane reaction again which can continue carbon growth further. EXAMPLE 2

[0140] In a specific example, methane pyrolysis was performed in a fluidized bed reactor. The reactor was a quartz tube with 90 cm length with tapered diameter from 1 cm at bottom and 2.5 cm at top. Approximately 12 g of sand and iron (20% Fe) was loaded in the reactor and methane was flowed through another tube at the bottom end. The reaction was performed at 950 ℃ with iron and 1200 ℃ without iron. The product gases were monitored though mass spectrometer and conversion was measured by gas chromatograph. The underlying phenomenon of the hydrocarbon reaction occurring on inert and metal surface such as iron is distinguishable. Figures 23A-23C shows the carbon produced have different attributes and morphologies. Carbon produced on iron surface is graphitic carbon since carbon produced on inert is amorphous. Figure 23A upper left TEM image shows a disordered carbon, similar observation is also received through Raman spectra which exhibit broad D and G peaks. EXAMPLE 3 Pyrolysis of methane in fluidized bed with different iron sources (Iron and iron oxide)34

[0141] In a specific example, methane was pyrolyzed into hydrogen and solid carbon in a sand bed fluidized bed reactor void fraction of 42 %. The reactor was a quartz tube with 90 cm length with tapered diameter from 1 cm at bottom and 2.5 cm at top. Approximately 12 g of sand and iron (20% Fe) was loaded in the reactor and methane was flowed through another tube at the bottom end. The reaction was performed at 950 ℃ with iron and iron oxide precursors. The product gases were monitored by mass spectrometer and conversion was measured through gas chromatograph. The carbon was deposited over iron and iron oxide in the form of Fe3C and graphitic carbon. The product gases were monitored by mass spectrometer and conversion was measured through gas chromatograph. The conversion increased initial and attained steady state in approximately 1.5 h and remained stable more than 8.5 h at 950 ℃ and 1.2 sec residence time. Figures 26A-26D shows XRD profile of iron and oxide after 12 h reaction. Thepeak at 2^^ ൌ ~26 degrees corresponds to graphitic carbon. The same peak also appearsin Fe3C but their peak intensity is very low. Peak positioned at ~45 degree could be attributed to the presence of graphitic carbon / iron or Fe3C also. The intensity of the peak position at ~45 degree is higher in the case of iron oxide than iron which is attributed to the high amount to C / Fe ratio. The atomic C / Fe ratio in both iron oxide and iron were 23 and 30 (4.92 and 6.6 by weight) respectively. Similarly, as C / Fe ratio is increasing over time the intensity of the peak position at ~45 degree is also decreasing which confirm the increasing C / Fe ratio over time. In the case of iron oxide, it is reduced to FeO and Fe while heating to reaction temperature (during preconditioning) and within 10 mins all the iron oxide is almost completely reduced to Fe and peak for iron carbide is start appearing. XRD pattern in Figure 26A shows that the catalyst sample contains a very low amount of iron in sample (less than 5%) and most of the iron is in the form of iron carbide which is encapsulated and a high intensity peak corresponding to graphitic carbon. On the other hand, iron directly participates in the fragmentation and carbon growth mechanism. However, more carbon is formed when 10 wt.% Fe was used as compared to 20 wt.% Fe because C / Fe ratio was higher in the case of 10 wt.% Fe as compared to 20 wt.% Fe. All type of precursor formed graphitic form of carbon.35

[0142] Further, particle size of the iron oxide changed over time and some carbon growth is observed in the form of fiber after time on stream experiment, as shown in Figure 32. Initially, particles are of 17 ^^m and there was not much change in particle size we started the reaction and within 10 minutes of reaction particle size was reduced to 500 nm and there after slow change in particles. Particles were of 200 nm after 120 min and 210 nm after end of reaction. Particles size changed due to reduction, fragmentation, carbon growth and particle encapsulation with carbon. EXAMPLE 4 Pyrolysis of methane in fluidized bed with single atom iron precursor

[0143] In a specific example, methane was pyrolyzed into hydrogen and solid carbon in a sand bed fluidized bed reactor void fraction of 42 % using different single atom iron precursor including nano iron and iron citrate at atmospheric pressure and 5 bar and high WHSV. A typical reactor consists a quartz tube tapered fluidized bed reactor connected with two pressure transducers and one back pressure control valve to regulate the pressure. Reactor was a tapered quartz tube reactor with 90 cm length with tapered diameter from 1 cm at bottom and 2.5 cm at top. Approximately 12 g of sand and iron was loaded in the reactor and methane was flowed through another tube at the bottom end. The bed height without any flow was around 15 cm with void fraction of 0.5. The product gases were monitored by mass spectrometer and conversion was measured through gas chromatograph connected after the back pressure regulator. At 5 bar, both nano iron and iron citrate shows the C / Fe ratio above 8 which is higher than the C / Fe ratio achieved with both iron and iron oxide precursor. However, atmospheric pressure results show lower C / Fe ratio due to lower WHSV and reaction rate as compared to 5 bar results. TEM and HAADF images of iron citrate at 5 bar also shows formed long flakes structures, as shown in Figure 33. EXAMPLE 5 Preparation of carbon deposited iron catalyst using pure iron36

[0144] In a specific example, pure iron powder was mixed with sand (20 wt.% Fe) and reduced in a fluidized bed reactor. The reactor was a quartz tube with 60 cm in length and 1.3 cm inside diameter heated at 950 ℃ and 0.73 sec residence time. Initially, the methane was flowing at a very high flow rate as temperature starts increasing, flow was adjusted to 0.73 sec residence time and iron oxide particles were reduced and fragmented in first 30-35 minutes it is the point when we reached approx.84% conversion at 1 bar and C / Fe ratio of 1 as shown in Figure 37. The carbon was deposited over iron in the form of Fe3C and graphitic carbon. EXAMPLE 6 Preparation of carbon deposited iron catalyst using iron oxide

[0145] In a specific example, natural iron oxide powder was mixed with sand (20 wt.% Fe) and reduced in a fluidized bed reactor. The reactor was a quartz tube with 60 cm in length and 1.3 cm inside diameter heated at 950 ℃ and 0.73 sec residence time. Initially, the methane was flowing at a very high flow rate as temperature starts increasing, flow was adjusted to 0.73 sec residence time and iron oxide particles were reduced and fragmented in first 30-35 minutes, it is the point when we reached approx. 95% conversion at 1 bar and C / Fe ratio of 1, as shown in Figure 38. The carbon was deposited over iron in the form of Fe3C and graphitic carbon. EXAMPLE 7 Hydrogen oxidation and methane pyrolysis in a dual bed reactor

[0146] In another example, hydrogen combustion and methane decomposition were performed all together in a single reactor using dual catalyst bed where bed 1 was 10% Pt / SiO2for the hydrogen combustion and a second catalyst bed 2 was the Fe3O4. Inlet gases were fed through a dual tube arrangement where inner tube was used to only flow methane for methane decomposition and outer tube was used to feed both hydrogen and oxygen for oxidation of hydrogen. The outlet point of outer tube was adjusted just before the catalyst bed 1 so there was no mixing with the gas for methane decomposition in bed 2. The outlet point of inner tube was just before the bed 2 and it passes through the bed 137    and it exchange the heat between reacting gases and flowing methane. The flow ratio of gas was 1:0.4:0.2 for CH4:H2:O2.

[0147] The reactor was a quartz tube with 60 cm in length and 1.3 cm inner diameter. The reaction was performed in the range of 850-950 ℃. The product gases were monitored though mass spectrometer and conversion was measured by gas chromatograph. There was no evidence of CO2formation in this reaction and only CO and H2 and H2O were formed. Water was captured through drierite before entering into GC and Mass spectrometer. The results show that above 60% methane was decomposed into hydrogen and carbon at 950 ℃, as shown in Figures 39A-39B. EXAMPLE 8 Pretreatment of iron ore and methane pyrolysis

[0148] In a specific example, iron ore (magnetite or hematite) was crushed and suspended in ethanol and ball milled at 20-3000 rpm (300 rpm) for 10 mins-12h (4hr). The iron ore could be both magnetite or hematite is of varying or fixed particle size, ranging from fine powder to pellet (10 um to 1-2 cm particle diameter). This iron ore paste was taken out and dried in over for 30 mins to 12h to make a fine dry powder. Then iron ore fine powder was mixed with sand (20 wt.% Fe) and oxidized / reduced in a fluidized bed reactor for 2 hr at 730 ℃. The oxidant could be CO, CO2, air or oxygen. It may be reduced either through hydrogen or methane. After oxidation / reduction, the methane was flowed and methane pyrolysis was at 950 ℃ and 1.1 sec residence time. Reactor was a tapered quartz tube reactor with 90 cm length with tapered diameter from 1 cm at bottom and 2.5 cm at top. The approx. 93% conversion was achieved at 1 bar and C / Fe ratio of 1.4 in 75 mins as shown in Figure 40. The carbon was deposited over iron in the form of Fe3C and graphitic carbon. EXAMPLE 9 Pretreatment of iron ore and methane pyrolysis

[0149] In another example, iron ore was crushed and suspended in ethanol and ball38    milled at 20-3000 rpm (300 rpm) for 10 mins-12h (4hr). The iron ore could be both magnetite or hematite is of varying or fixed particle size, ranging from fine powder to pellet (10 um to 1-2 cm particle diameter). This iron ore paste was taken out and dried in over for 30 mins to 12h to make a fine dry powder. Then iron ore fine powder was mixed with sand (20 wt.% Fe) and oxidized / reduced in a fluidized bed reactor for 4 hr at 700 ℃. The oxidant could be CO, CO2, air or oxygen. It may be reduced either through hydrogen or methane. After oxidation, the methane was flowed and methane pyrolysis was at 950 ℃ and 1.1 sec residence time. Reactor was a tapered quartz tube reactor with 90 cm length with tapered diameter from 1 cm at bottom and 2.5 cm at top. The approx. 94% conversion was achieved at 1 bar and C / Fe ratio of 5.56 before deactivation Figure 41. The carbon was deposited over iron in the form of Fe3C and graphitic carbon. EXAMPLE 10 Pretreatment of iron ore and methane pyrolysis

[0150] In another example, iron ore was crushed and suspended in ethanol and ball milled at 300 rpm for 30 mins. The iron ore could be both magnetite or hematite is of varying or fixed particle size, ranging from fine powder to pellet (10 um to 1-2 cm particle diameter). This iron ore paste was taken out and dried in over for 30 mins to 12h to make a fine dry powder. Then iron ore fine powder was mixed with sand (20 wt.% Fe) and oxidized / reduced in a fluidized bed reactor for 4 hr at 700 ℃. The oxidant could be CO, CO2, air or oxygen. It may be reduced either through hydrogen or methane. After oxidation, the methane was flowed and methane pyrolysis was at 950 ℃ and 1.1 sec residence time. Reactor was a tapered quartz tube reactor with 90 cm length with tapered diameter from 1 cm at bottom and 2.5 cm at top. The approx. 84% conversion was achieved at 1 bar and C / Fe ratio of 0.5 in 75 mins Figure 42. The carbon was deposited over iron in the form of Fe3C and graphitic carbon. EXAMPLE 11 Continuous Operation of Fluidized Bed Reactor39

[0151] In a specific example, methane was pyrolyzed into hydrogen and solid carbon in a sand bed fluidized bed reactor with continuous addition of fresh catalyst and subsequent removal of deactivated catalyst at 1 bar and 950 ℃ and high WHSV. Reactor was a tapered quartz tube reactor with 90 cm length with tapered diameter from 1 cm at bottom and 2.5 cm at top with two connection each for fresh catalyst addition and the removal of deactivated catalyst. Approximately 12 g of sand and iron oxide (20% Fe in sand) was loaded in the reactor and methane was flowed through another tube at the bottom end. The bed height without any flow was around 15 cm with void fraction of 0.5. The product gases were monitored by mass spectrometer and conversion was measured through gas chromatograph connected after the back pressure regulator. Once, conversion reached maximum after approximately 85 mins, another batch of catalyst without sand was added in the reactor. Conversion was maintained at ~95% for another 80 mins and flow was increased to maintain the fluidization, Figure 43. After another 85 mins another batch of catalyst was added with subsequent removal of deactivated catalyst fluidizing in upper zone due to lower bulk density. Fluidized bed segregated based on their particle size and particle density, fragmented and encapsulated catalyst being on the top. These steps were repeated till 4 catalyst addition cycle. After the last cycle, activity starts decreasing due to carbon encapsulation and catalyst deactivation. C / Fe ratio above 5 which was archived which was comparable with single batch experiments Figure 44. EXAMPLE 12 High pressure fluidized bed reactor at constant superficial gas velocity

[0152] In a specific example, methane was pyrolyzed into hydrogen and solid carbon in a sand bed fluidized bed reactor void fraction of 42 % at 1 bar, 3 bar and 5 bar and constant superficial gas velocity. A typical reactor consists a quartz tube tapered fluidized bed reactor connected with two pressure transducers and one back pressure control valve to regulate the pressure. Reactor was a tapered quartz tube reactor with 90 cm length with tapered diameter from 1 cm at bottom and 2.5 cm at top. Approximately 12 g of sand and iron was loaded in the reactor and methane was flowed through another tube at the bottom40    end. The bed height without any flow was around 15 cm with void fraction of 0.5. The product gases were monitored by mass spectrometer and conversion was measured through gas chromatograph connected after the back pressure regulator. In all experiments, t=0-50min reduction was completed in pure CH4 at 1 bar WHSV = 3.5hr-1. At 50 min, pressure was increased and flowrate increased for constant superficial gas velocity. Approx. 75-80% conversion can be achieved at 5 bar and 950 C. and 50% at 850 C can be achieved while maintaining the C / Fe ratio of above 6, Figure 45. EXAMPLE 13 High pressure fluidized bed reactor at constant WHSV

[0153] In a specific example, methane was pyrolyzed into hydrogen and solid carbon in a sand bed fluidized bed reactor void fraction of 42 % at 1 bar, 3 bar and 5 bar and constant WHSV, Figures 46A-46C. A typical reactor consists a quartz tube tapered fluidized bed reactor connected with two pressure transducers and one back pressure control valve to regulate the pressure. Reactor was a tapered quartz tube reactor with 90 cm length with tapered diameter from 1 cm at bottom and 2.5 cm at top. Approximately 12 g of sand and iron was loaded in the reactor and methane was flowed through another tube at the bottom end. The bed height without any flow was around 15 cm with void fraction of 0.5. The product gases were monitored by mass spectrometer and conversion was measured through gas chromatograph connected after the back pressure regulator. In all experiments, t=0-50 min reduction was completed in pure CH4 at 1 bar WHSV = 3.5hr-1. At 50 min, pressure was increased and flowrate increased for constant superficial gas velocity. Approx. 75-80% conversion can be achieved at 5 bar and 950 ℃. and 50% at 850 ℃ can be achieved while maintaining the C / Fe ratio of above 6, Figures 47A-47B. It is worthy to note that the after 120 mins, carbon which is forming is disordered carbon it is forming due to the presence of surface irregularities. After 120 mins, almost all of the iron is encapsulated and graphitic carbon is nonporous and now methane is not reaching to iron particles. Long run resulted into formation of disordered carbon and degree of graphitization is decreased which shows that the methane is reacting at the surface of41    carbon and forming disordered carbon. This also confirms the hypothesis of deactivation due to carbon encapsulation and iron is not accessible to methane to react further (Probably due to the formation of non-porous graphitic layer). EXAMPLE 14 High pressure packed bed reactor

[0154] In a specific example, methane was pyrolyzed into hydrogen and solid carbon in a sand bed fluidized bed reactor void fraction of 42 % at 5 bar and varying WHSV, Figures 48A-48B. A typical reactor consists a quartz tube packed bed reactor connected with two pressure transducers and one back pressure control valve to regulate the pressure. Reactor was a tapered quartz tube reactor with 90 cm length with 1.3 cm. Approximately 0.25 gms Fe as Fe / Fe3C was mixed with quartz wool and loaded in the reactor and methane was flowed through bottom end. The bed height was 20 cm. The product gases were monitored by mass spectrometer and conversion was measured through gas chromatograph connected after the back pressure regulator. In all experiments, catalyst was prepared in same way as discussed in EXAMPLE 8. Approx. 90% conversion can be achieved at 5 bar, 950 ℃ and 10.5 h-1and 50% at 850 ℃ can be achieved while maintaining the C / Fe ratio of above 8, Figure 48B. The carbon was deposited over iron in the form of Fe3C and graphitic carbon. EXAMPLE 15 Pyrolysis of methane with heat provided by autothermal reforming in a single bed reactor (Packed bed)

[0155] In specific example, hydrogen oxidation and methane decomposition were performed all together in a single bed reactor (packed bed) using Fe3O4 as a catalyst. The reactor was a quartz tube reactor with 60 cm length with 1.3 cm inner diameter and 30 cm heated zone length. Approximately 1.20 g of iron in Fe3O4 was diluted with quartz wool powder and loaded in the reactor. The bed length was 20 cm and total volume was 28.6 cm3. Methane gas was fed from bottom and hydrogen and oxygen were fed from top42    through a dual tube arrangement where inner tube was used to only flow oxygen and outer tube was used to feed hydrogen for oxidation process. The outlet point of top tubes was at the center of the bed and it passes through the bed and it exchange the heat between reacting gases and catalyst bed. The flow ratio of gas was 1:0.4:0.2 for CH4:H2:O2. The reaction was performed at 950 ℃. The product gases were monitored though mass spectrometer and conversion were measured by gas chromatogram. There was no evidence of CO2 formation in this reaction and only CO and H2 and H2O were formed. Water was captured through drierite before entering into GC and Mass spectrometer. The results shows that above 80% methane was decomposed into hydrogen and carbon at 950 ℃, Figures 49A-49D. The reacting zone of steam and methane shows a very graphitic carbon formation over iron particles whereas non reacting zone of steam where methane decomposition is predominant and there is formation of less graphitic carbon also. EXAMPLE 16 Pyrolysis of methane with heat provided by autothermal reforming in a single bed reactor (Fluidized bed)

[0156] In a specific example, methane was pyrolysed into hydrogen and solid carbon in a sand bed fluidized bed reactor at 1 bar and 950 ℃ and high WHSV. Reactor was a tapered quartz tube reactor with 90 cm length with tapered diameter from 1 cm at bottom and 2.5 cm at top. Approximately 12 g of sand and iron oxide (20% Fe in sand) was loaded in the reactor and methane was flowed through inner tube at the bottom end whereas hydrogen and oxygen mixture was fed through another tube at the top zone of catalyst bed. The bed height without any flow was around 15 cm with void fraction of 0.5. The product gases were monitored by mass spectrometer and conversion was measured through gas chromatograph connected after the back pressure regulator. Once, conversion reached maximum after approximately 15 mins, and hydrogen and oxygen flow was started at this point. The flow ratio of gas was 1:0.4:0.2 for CH4:H2:O2. There was no evidence of CO2 formation in this reaction and only CO and H2 and H2O were formed. Water was captured through drierite before entering into GC and Mass spectrometer. The results shows that above 90% methane was decomposed into hydrogen43    and carbon at 950 ℃, as shown in Figures 50A-50C. The H2:CO ratio was approximately 15. EXAMPLE 17 Pyrolysis of methane with heat provided by autothermal reforming in a single bed reactor (Packed bed)

[0157] In specific example, hydrogen oxidation and methane decomposition were performed all together in a single bed reactor (packed bed) using Fe3O4as a catalyst. The reactor was a quartz tube reactor with 60 cm length with 1.3 cm inner diameter and 30 cm heated zone length. Approximately 1.20 g of iron in Fe3O4was diluted with quartz wool powder and loaded in the reactor. The bed length was 20 cm and total volume was 28.6 cm3. Methane gas was fed from bottom and hydrogen and oxygen were fed from top through a dual tube arrangement where inner tube was used to only flow oxygen and outer tube was used to feed hydrogen for oxidation process. The outlet point of top tubes was at the center of the bed and it passes through the bed and it exchange the heat between reacting gases and catalyst bed. The flow ratio of gas was 1:0.6:0.3 for CH4:H2:O2. The reaction was performed at 950 ℃. The product gases were monitored though mass spectrometer and conversion were measured by gas chromatogram. There was no evidence of CO2 formation in this reaction and only CO and H2 and H2O were formed. Water was captured through drierite before entering into GC and Mass spectrometer. The results shows that above 80% methane was decomposed into hydrogen and carbon at 950 ℃, Figures 51A-51C. The H2:CO ratio was approximately 5. EXAMPLE 18 Internal Particulate Circulation

[0158] The internal circulation of sand as an inert material was demonstrated as shown schematically in Figure 52A. In this example, a 2.5 cm diameter quartz reactor tube 70 cm in length was used with an internal riser tube fitted to deposit heated sand on top of the iron containing catalyst bed which stratified to the top. Figure 52B shows the44    circulating sand prior to inserting the catalyst. The sand was circulated using a stoichiometric combustion mixture of air and hydrogen flowing at 5 m / s. The combustion gas heated sand maintained the reactor within an insulated electric heater at a temperature of 950 °C. Catalyst was added along with a methane feed. The experiment was conducted in semi-batch mode and no fresh catalyst was added and no catalyst removed. Minimal CO was observed in the product gases and the methane conversion increased to 95% and then decreased as the catalyst deactivated.

[0159] Having disclosed various reactors, systems, processes, and methods, certain aspect can include, but are not limited to (referring to reference numbers in the figures as non-limiting illustrative examples only; embodiments of the following aspects may optionally use the processes and reactors illustrated in figs 1-19, 21, 25, 27, 28, 29-31, 35, for example) :

[0160] In a first aspect, a process for producing hydrogen from hydrocarbons comprises: contacting a hydrocarbon with a catalyst and inert particles in a reactor (e.g., 104); producing solid carbon and hydrogen based on the contacting; removing a portion of the inert particles from the reactor (e.g., in separator 106); heating the portion of the inert particles in a heating loop (e.g., 202) to produce heated inert particles; returning the heated inert particles to an upper portion of the reactor; and heating the reactor during the contacting based on returning the heated inert particles.

[0161] A second aspect can include the process of the first aspect, wherein heating the portion of the inert particles in the heating loop comprises using electrical heat, combustion of hydrogen, combustion of hydrocarbons, or a combination thereof to heat the portion of the inert particles in the heating loop.

[0162] A third aspect can include the process of the second aspect, wherein heating the portion of the inert particles in the heating loop further comprises using renewable electricity to heat the portion of the inert particles in the heating loop.

[0163] A fourth aspect can include the process of any one of the first to third aspects, further comprising: removing at least a portion of the catalyst and solid carbon from the reactor; separating a portion of the catalyst from the solid carbon; and recycling the45    separated portion of the catalyst to the reactor.

[0164] A fifth aspect can include the process of the fourth aspect, further comprising: mixing fresh catalyst with separated portion of the catalyst prior to recycling the separated portion of the catalyst to the reactor.

[0165] A sixth aspect can include the process of any one of the first to fifth aspects, wherein the inert particles flow from the upper portion of the reactor to a lower portion of the reactor, and wherein the hydrocarbon and solid carbon circulate from the lower portion of the reactor to an upper portion of the reactor.

[0166] A seventh aspect can include the process of any one of the first to sixth aspects, wherein the catalyst comprises a transition metal.

[0167] An eighth aspect can include the process of any one of the first to seventh aspects, wherein the catalyst comprises iron, nickel, cobalt, or any combination thereof.

[0168] A ninth aspect can include the process of any one of the first to eighth aspects, wherein the solid carbon comprises graphitic carbon, carbon nanotubes, or any combination thereof.

[0169] A tenth aspect can include the process of any one of the first to ninth aspects, wherein the catalyst comprises: iron ore, iron carbide, iron salts (e.g., halides, nitrates, carbonates, sulfates, etc.), or any combination thereof.

[0170] An eleventh aspect can include the process of any one of the first to tenth aspects, wherein the catalyst comprises: iron pentacarbonyl, ferrocene, iron chloride, iron citrate, iron nitrate, or any combination thereof.

[0171] A twelfth aspect can include the process of the eleventh aspect, further comprising: decomposing the catalyst to form iron atoms during the production of the solid carbon.

[0172] A thirteenth aspect can include the process of any one of the first to twelfth aspects, wherein the solid carbon forms on the catalyst, where the method further comprises: contacting the catalyst with the solid carbon with a halogen to form a metal halide in the vapor phase; condensing the metal halide; reacting the metal halide with oxygen to recover the halogen and form a metal oxide; and introducing the metal oxide46    to the reactor as a portion of the catalyst.

[0173] A fourteenth aspect can include the process of any one of the first to twelfth aspects, wherein the solid carbon forms on the catalyst, where the method further comprises: contacting the catalyst with the solid carbon with carbon monoxide to form a metal carbonyl in the vapor phase; condensing the metal carbonyl; and introducing the metal carbonyl to the reactor as a portion of the catalyst.

[0174] A fifteenth aspect can include the process of any one of the first to twelfth aspects, wherein the solid carbon forms on the catalyst, where the method further comprises: contacting the catalyst with the solid carbon with an acid to form a metal salt; dissolving the metal salt in a solvent; recovering the metal salt from the solvent; and introducing the metal salt to the reactor as a portion of the catalyst.

[0175] A sixteenth aspect can include the process of any one of the first to fifteenth aspects, wherein the solid carbon forms on the catalyst, where the method further comprises: contacting the catalyst with the solid carbon with an oxidant.

[0176] A seventeenth aspect can include the process of the sixteenth aspect, wherein the oxidant comprises H2O, CO2, O2, Sn, Cl2, Br2, or any combination thereof.

[0177] An eighteenth aspect can include the process of any one of the first to seventeenth aspects, wherein the reactor is operated as a fluidized bed in a fast fluidization flow regime and / or turbulent flow regime.

[0178] A nineteenth aspect can include the process of any one of the first to eighteenth aspects, wherein the reactor comprises a cold wall design.

[0179] A twentieth aspect can include the process of any one of the first to nineteenth aspects, wherein the reactor operates at a temperature in a range of from 650-1100 °C

[0180] A twenty first aspect can include the process of any one of the first to twentieth aspects, wherein the reactor operates at a pressure in a range of from 1-50 Bar.

[0181] In a twenty second aspect, a process for producing hydrogen from hydrocarbons comprises: combusting a reactant in a reactor to produce heat within the reactor; contacting a hydrocarbon with a catalyst in the reactor; producing solid carbon and hydrogen based on the contacting; and heating the reactor during the contacting based on47    the combusting.

[0182] A twenty third aspect can include the process of the twenty second aspect, wherein the reactant comprises hydrogen, and wherein the hydrogen is combusted with oxygen within the reactor to produce steam.

[0183] A twenty fourth aspect can include the process of the twenty third aspect, wherein the reactant is combusted with oxygen within the reactor to produce the heat and a carbon oxide, and wherein the carbon oxide is converted to an alcohol, an olefin, acetic acid, or any combination thereof.

[0184] A twenty fifth aspect can include the process of the twenty second aspect, wherein the reactant comprises a hydrogen halide, and wherein the hydrogen halide is combusted with oxygen within the reactor to produce steam and an elemental halide, and wherein the elemental halide reacts with the hydrocarbon to produce solid carbon and the hydrogen halide.

[0185] A twenty sixth aspect can include the process of the twenty fifth aspect, wherein the hydrogen halide comprises hydrogen chloride or hydrogen bromide.

[0186] A twenty seventh aspect can include the process of any one of the twenty second to twenty sixth aspects, further comprising: removing at least a portion of the catalyst and solid carbon from the reactor; separating a portion of the catalyst from the solid carbon; and recycling the separated portion of the catalyst to the reactor.

[0187] A twenty eighth aspect can include the process of the twenty seventh aspect, further comprising: mixing fresh catalyst with separated portion of the catalyst prior to recycling the separated portion of the catalyst to the reactor.

[0188] A twenty ninth aspect can include the process of the twenty second aspect, wherein the reactant comprises a hydrogen halide, and wherein the hydrogen halide is combusted with oxygen within the reactor to produce steam and an elemental halide.

[0189] A thirtieth aspect can include the process of any one of the twenty second to twenty ninth aspects, wherein the solid carbon comprises graphitic carbon, carbon nanotubes, or any combination thereof.

[0190] A thirty first aspect can include the process of any one of the twenty second to48    thirtieth aspects, wherein the catalyst comprises a transition metal.

[0191] A thirty second aspect can include the process of any one of the twenty second to thirty first aspects, wherein the catalyst comprises iron, nickel, cobalt, or any combination thereof.

[0192] A thirty third aspect can include the process of any one of the twenty second to thirty second aspects, wherein the catalyst comprises: iron ore, iron carbide, iron salts (e.g., halides, nitrates, carbonates, sulfates, etc.), or any combination thereof.

[0193] A thirty fourth aspect can include the process of any one of the twenty second to thirty third aspects, wherein the catalyst comprises: iron pentacarbonyl, ferrocene, iron chloride, iron citrate, iron nitrate, or any combination thereof.

[0194] A thirty fifth aspect can include the process of the thirty fourth aspect, further comprising: decomposing the catalyst to form iron atoms during the production of the solid carbon.

[0195] A thirty sixth aspect can include the process of any one of the thirty first to thirty fifth aspects, wherein the solid carbon forms on the catalyst, where the method further comprises: contacting the catalyst with the solid carbon with a halogen to form a metal halide in the vapor phase; condensing the metal halide; reacting the metal halide with oxygen to recover the halogen and form a metal oxide; and introducing the metal oxide to the reactor as a portion of the catalyst.

[0196] A thirty seventh aspect can include the process of any one of the thirty first to thirty fifth aspects, wherein the solid carbon forms on the catalyst, where the method further comprises: contacting the catalyst with the solid carbon with carbon monoxide to form a metal carbonyl in the vapor phase; condensing the metal carbonyl; and introducing the metal carbonyl to the reactor as a portion of the catalyst.

[0197] A thirty eighth aspect can include the process of any one of the thirty first to thirty fifth aspects, wherein the solid carbon forms on the catalyst, where the method further comprises: contacting the catalyst with the solid carbon with an oxidant.

[0198] A thirty ninth aspect can include the process of the thirty eighth aspect, wherein the oxidant comprises H2O, CO2, O2, Sn, Cl2, Br2, or any combination thereof.49

[0199] A fortieth aspect can include the process of any one of the twenty second to thirty ninth aspects, wherein the reactor is operated as a fluidized bed in a fast fluidization flow regime and / or turbulent flow regime.

[0200] A forty first aspect can include the process of any one of the twenty second to fortieth aspects, wherein the reactor comprises a cold wall design.

[0201] A forty second aspect can include the process of any one of the twenty second to forty first aspects, wherein the reactor operates at a temperature in a range of from 650- 1100 °C

[0202] A forty third aspect can include the process of any one of the twenty second to forty second aspects, wherein the reactor operates at a pressure in a range of from 1-50 Bar.

[0203] A forty fourth aspect can include the process of the twenty second aspect, further comprising: contacting the hydrocarbon with inert particles in the reactor; heating the inert particles in the reactor using the produced heat; circulating the inert particles within the reactor during the combusting; and heating the reactor based the circulating.

[0204] In a forty fifth aspect, a process for producing hydrogen from hydrocarbons comprises: contacting a hydrocarbon with a catalyst in a reactor; producing solid carbon and hydrogen based on the contacting; removing a portion of the solid carbon and catalyst during the contacting; and introducing a catalyst promoter during the contacting.

[0205] A forty sixth aspect can include the process of the forty fifth aspect, wherein the solid carbon comprises graphitic carbon, carbon nanotubes, or any combination thereof.

[0206] A forty seventh aspect can include the process of the forty fifth or forty sixth aspect, wherein the catalyst comprises a transition metal.

[0207] A forty eighth aspect can include the process of any one of the forty fifth to forty seventh aspects, wherein the catalyst comprises iron, nickel, cobalt, or any combination thereof.

[0208] A forty ninth aspect can include the process of the forty fifth aspect, wherein the catalyst comprises iron.

[0209] A fiftieth aspect can include the process of any one of the forty fifth to forty50    ninth aspects, wherein the catalyst comprises: iron ore, iron carbide, iron salts (e.g., halides, nitrates, carbonates, sulfates, etc.), or any combination thereof.

[0210] A fifty first aspect can include the process of any one of the forty fifth to fiftieth aspects, wherein the promoter comprises sulfur, chlorine, oxygen, carbon dioxide, carbon disulfide, methane thiol, thiophene, or any combination thereof.

[0211] A fifty second aspect can include the process of any one of the forty fifth to fifty first aspects, wherein the reactor comprises a cold wall design.

[0212] A fifty third aspect can include the process of any one of the forty fifth to fifty second aspects, wherein the reactor operates at a temperature in a range of from 650-1100 °C

[0213] A fifty fourth aspect can include the process of any one of the forty fifth to fifty third aspects, wherein the reactor operates at a pressure in a range of from 1-50 Bar.

[0214] Embodiments are discussed herein with reference to the Figures. However, those skilled in the art will readily appreciate that the detailed description given herein with respect to these figures is for explanatory purposes as the systems and methods extend beyond these limited embodiments. For example, it should be appreciated that those skilled in the art will, in light of the teachings of the present description, recognize a multiplicity of alternate and suitable approaches, depending upon the needs of the particular application, to implement the functionality of any given detail described herein, beyond the particular implementation choices in the following embodiments described and shown. That is, there are numerous modifications and variations that are too numerous to be listed but that all fit within the scope of the present description. Also, singular words should be read as plural and vice versa and masculine as feminine and vice versa, where appropriate, and alternative embodiments do not necessarily imply that the two are mutually exclusive.

[0215] It is to be further understood that the present description is not limited to the particular methodology, compounds, materials, manufacturing techniques, uses, and applications, described herein, as these may vary. It is also to be understood that the terminology used herein is used for the purpose of describing particular embodiments51    only, and is not intended to limit the scope of the present systems and methods. It must be noted that as used herein and in the appended claims (in this application, or any derived applications thereof), the singular forms "a," "an," and "the" include the plural reference unless the context clearly dictates otherwise. Thus, for example, a reference to "an element" is a reference to one or more elements and includes equivalents thereof known to those skilled in the art. All conjunctions used are to be understood in the most inclusive sense possible. Thus, the word "or" should be understood as having the definition of a logical "or" rather than that of a logical "exclusive or" unless the context clearly necessitates otherwise. Structures described herein are to be understood also to refer to functional equivalents of such structures. Language that may be construed to express approximation should be so understood unless the context clearly dictates otherwise.

[0216] Unless defined otherwise, all technical and scientific terms used herein have the same meanings as commonly understood by one of ordinary skill in the art to which this description belongs. Preferred methods, techniques, devices, and materials are described, although any methods, techniques, devices, or materials similar or equivalent to those described herein may be used in the practice or testing of the present systems and methods. Structures described herein are to be understood also to refer to functional equivalents of such structures. The present systems and methods will now be described in detail with reference to embodiments thereof as illustrated in the accompanying drawings.

[0217] From reading the present disclosure, other variations and modifications will be apparent to persons skilled in the art. Such variations and modifications may involve equivalent and other features which are already known in the art, and which may be used instead of or in addition to features already described herein.

[0218] Although claims may be formulated in this application or of any further application derived therefrom, to particular combinations of features, it should be understood that the scope of the disclosure also includes any novel feature or any novel combination of features disclosed herein either explicitly or implicitly or any generalization thereof, whether or not it relates to the same systems or methods as52    presently claimed in any claim and whether or not it mitigates any or all of the same technical problems as do the present systems and methods.

[0219] Features which are described in the context of separate embodiments may also be provided in combination in a single embodiment. Conversely, various features which are, for brevity, described in the context of a single embodiment, may also be provided separately or in any suitable sub-combination. The Applicant(s) hereby give notice that new claims may be formulated to such features and / or combinations of such features during the prosecution of the present Application or of any further Application derived therefrom.53

Claims

Claims What is claimed is:

1. A process for producing hydrogen from hydrocarbons, the process comprising: contacting a hydrocarbon with a catalyst and inert particles in a reactor; producing solid carbon and hydrogen based on the contacting; removing a portion of the inert particles from the reactor; heating the portion of the inert particles in a heating loop to produce heated inert particles; returning the heated inert particles to an upper portion of the reactor; and heating the reactor during the contacting based on returning the heated inert particles.

2. The process of claim 1, wherein heating the portion of the inert particles in the heating loop comprises using electrical heat, combustion of hydrogen, combustion of hydrocarbons, or a combination thereof to heat the portion of the inert particles in the heating loop.

3. The process of claim 2, wherein heating the portion of the inert particles in the heating loop further comprises using renewable electricity to heat the portion of the inert particles in the heating loop.

4. The process of claim 1, further comprising: removing at least a portion of the catalyst and solid carbon from the reactor; separating a portion of the catalyst from the solid carbon; and recycling the separated portion of the catalyst to the reactor.

5. The process of claim 4, further comprising: mixing fresh catalyst with separated portion of the catalyst prior to recycling the separated portion of the catalyst to the reactor.54    6. The process of claim 1, wherein the inert particles flow from the upper portion of the reactor to a lower portion of the reactor, and wherein the hydrocarbon and solid carbon circulate from the lower portion of the reactor to an upper portion of the reactor.

7. The process of claim 1, wherein the catalyst comprises a transition metal.

8. The process of claim 1, wherein the catalyst comprises iron, nickel, cobalt, or any combination thereof.

9. The process of claim 1, wherein the solid carbon comprises graphitic carbon, carbon nanotubes, or any combination thereof.

10. The process of claim 1, wherein the catalyst comprises: iron ore, iron carbide, iron salts (e.g., halides, nitrates, carbonates, sulfates, etc.), or any combination thereof.

11. The process of claim 1, wherein the catalyst comprises: iron pentacarbonyl, ferrocene, iron chloride, iron citrate, iron nitrate, or any combination thereof.

12. The process of claim 11, further comprising: decomposing the catalyst to form iron atoms during the producing of the solid carbon.

13. The process of claim 1, wherein the solid carbon forms on the catalyst, where the method further comprises: contacting the catalyst with the solid carbon with a halogen to form a metal halide in the vapor phase; condensing the metal halide; reacting the metal halide with oxygen to recover the halogen and form a metal oxide; and55    introducing the metal oxide to the reactor as a portion of the catalyst.

14. The process of claim 1, wherein the solid carbon forms on the catalyst, where the method further comprises: contacting the catalyst with the solid carbon with carbon monoxide to form a metal carbonyl in the vapor phase; condensing the metal carbonyl; and introducing the metal carbonyl to the reactor as a portion of the catalyst.

15. The process of claim 1, wherein the solid carbon forms on the catalyst, where the method further comprises: contacting the catalyst with the solid carbon with an acid to form a metal salt; dissolving the metal salt in a solvent; recovering the metal salt from the solvent; and introducing the metal salt to the reactor as a portion of the catalyst.

16. The process of claim 1, wherein the solid carbon forms on the catalyst, where the method further comprises: contacting the catalyst with the solid carbon with an oxidant.

17. The process of claim 16, wherein the oxidant comprises H2O, CO2, O2, Sn, Cl2, Br2, or any combination thereof.

18. The process of claim 1, wherein the reactor is operated as a fluidized bed in a fast fluidization flow regime and / or turbulent flow regime.

19. The process of claim 1, wherein the reactor comprises a cold wall design.

20. The process of claim 1, wherein the reactor operates at a temperature in a range of from 650-1100 °C.56    21. The process of claim 1, Wherein the reactor operates at a pressure in a range of from 1-50 Bar.

22. A process for producing hydrogen from hydrocarbons, the process comprising: combusting a reactant in a reactor to produce heat within the reactor; contacting a hydrocarbon with a catalyst in the reactor; producing solid carbon and hydrogen based on the contacting; and heating the reactor during the contacting based on the combusting.

23. The process of claim 22, wherein the reactant comprises hydrogen, and wherein the hydrogen is combusted with oxygen within the reactor to produce steam.

24. The process of claim 23, wherein the reactant is combusted with oxygen within the reactor to produce the heat and a carbon oxide, and wherein the carbon oxide is converted to an alcohol, an olefin, acetic acid, or any combination thereof.

25. The process of claim 22, wherein the reactant comprises a hydrogen halide, and wherein the hydrogen halide is combusted with oxygen within the reactor to produce steam and an elemental halide, and wherein the elemental halide reacts with the hydrocarbon to produce the solid carbon and the hydrogen halide.

26. The process of claim 25, wherein the hydrogen halide comprises hydrogen chloride or hydrogen bromide.

27. The process of claim 22, further comprising: removing at least a portion of the catalyst and the solid carbon from the57    reactor; separating a portion of the catalyst from the solid carbon; and recycling the separated portion of the catalyst to the reactor.

28. The process of claim 27, further comprising: mixing fresh catalyst with separated portion of the catalyst prior to recycling the separated portion of the catalyst to the reactor.

29. The process of claim 22, wherein the reactant comprises a hydrogen halide, and wherein the hydrogen halide is combusted with oxygen within the reactor to produce steam and an elemental halide.

30. The process of claim 22, wherein the solid carbon comprises graphitic carbon, carbon nanotubes, or any combination thereof.

31. The process of claim 22, wherein the catalyst comprises a transition metal.

32. The process of claim 22, wherein the catalyst comprises iron, nickel, cobalt, or any combination thereof.

33. The process of claim 22, wherein the catalyst comprises: iron ore, iron carbide, iron salts (e.g., halides, nitrates, carbonates, sulfates, etc.), or any combination thereof.

34. The process of claim 22, wherein the catalyst comprises: iron pentacarbonyl, ferrocene, iron chloride, iron citrate, iron nitrate, or any combination thereof.

35. The process of claim 34, further comprising: decomposing the catalyst to form iron atoms during the producing of the solid carbon.58    36. The process of claim 31, wherein the solid carbon forms on the catalyst, where the method further comprises: contacting the catalyst with the solid carbon with a halogen to form a metal halide in the vapor phase; condensing the metal halide; reacting the metal halide with oxygen to recover the halogen and form a metal oxide; and introducing the metal oxide to the reactor as a portion of the catalyst.

37. The process of claim 31, wherein the solid carbon forms on the catalyst, where the method further comprises: contacting the catalyst with the solid carbon with carbon monoxide to form a metal carbonyl in the vapor phase; condensing the metal carbonyl; and introducing the metal carbonyl to the reactor as a portion of the catalyst.

38. The process of claim 31, wherein the solid carbon forms on the catalyst, where the method further comprises: contacting the catalyst with the solid carbon with an oxidant.

39. The process of claim 38, wherein the oxidant comprises H2O, CO2, O2, Sn , Cl2, Br2, or any combination thereof.

40. The process of claim 22, wherein the reactor is operated as a fluidized bed in a fast fluidization flow regime and / or turbulent flow regime.

41. The process of claim 22, wherein the reactor comprises a cold wall design.

42. The process of claim 22, wherein the reactor operates at a temperature in a range of from 650-1100 °C.59    43. The process of claim 22, Wherein the reactor operates at a pressure in a range of from 1-50 Bar.

44. The process of claim 22, further comprising: contacting the hydrocarbon with inert particles in the reactor; heating the inert particles in the reactor using the produced heat; circulating the inert particles within the reactor during the combusting; and heating the reactor based the circulating.

45. A process for producing hydrogen from hydrocarbons, the process comprising: contacting a hydrocarbon with a catalyst in a reactor; producing solid carbon and hydrogen based on the contacting; removing a portion of the solid carbon and catalyst during the contacting; and introducing a catalyst promoter during the contacting.

46. The process of claim 45, wherein the solid carbon comprises graphitic carbon, carbon nanotubes, or any combination thereof.

47. The process of claim 45, wherein the catalyst comprises a transition metal.

48. The process of claim 45, wherein the catalyst comprises iron, nickel, cobalt, or any combination thereof.

49. The process of claim 45, wherein the catalyst comprises iron.

50. The process of claim 45, wherein the catalyst comprises: iron ore, iron carbide, iron salts (e.g., halides, nitrates, carbonates, sulfates, etc.), or any combination thereof.60    51. The process of claim 45, wherein the promoter comprises sulfur, chlorine, oxygen, carbon dioxide, carbon disulfide, methane thiol, thiophene, or any combination thereof.

52. The process of claim 45, wherein the reactor comprises a cold wall design.

53. The process of claim 45, wherein the reactor operates at a temperature in a range of from 650-1100 °C.

54. The process of claim 45, Wherein the reactor operates at a pressure in a range of from 1-50 Bar.61

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