Catalyst for CARGEN, preparation method and use thereof

Abstract

The present invention discloses a high conversion and high carbon yield CARGEN catalyst and a method for preparing the same. The catalyst comprises a transition metal which may be supported or unsupported. The preparation method involves mixing the metal material with or without a support in a standard ball milling apparatus to produce a fine and homogeneous solid mixture of transition metal oxide and support. The catalyst is used in a CARGEN system.

Description

[0001] priority

[0002] This application claims priority to U.S. Serial No. 62 / 949,133, filed December 17, 2019, the entire contents of which are incorporated herein by reference. Background Art

[0003] Methane reforming is one of the most common industrial processes for converting organic compounds (e.g., natural gas, which is primarily composed of methane) into synthetic gas (or "syngas") using an oxidant. Syngas, which is primarily a mixture of hydrogen and carbon monoxide, is an important feedstock for the production of a variety of value-added chemicals, particularly hydrocarbon fractions such as liquid transportation fuels such as methanol and dimethyl ether produced via Fischer-Tropsch synthesis. The oxidant used for methane reforming determines its type. For example, in the case of steam reforming, steam is used as the oxidant. Steam reforming of methane uses the following reaction, where ΔH 298 =206 kJ / mol

[0004] CH4+H2O→CO+3H2 (1)

[0005] In partial oxidation, oxygen is used as the oxidant to produce synthesis gas. The partial oxidation of methane is carried out as follows, where ΔH 298 =-43kJ / mol

[0006]

[0007] In dry reforming, carbon dioxide is used for oxidation purposes, where ΔH 298 =247 kJ / mol

[0008]

[0009] Most of the research in methane reforming is devoted to improving the reactant conversion by new catalyst materials or by optimizing the operating conditions for the set goals. Recently, the "dry" reforming of methane has attracted attention because it can convert two greenhouse gases (i.e., methane and carbon dioxide) into synthesis gas. However, the commercial applicability of dry reforming of methane is very limited due to its inherent process limitations (such as carbon deposition, high endothermicity of the reaction, and low synthesis gas yield ratio (H2:CO) values). The widely accepted path for forming carbon from methane during the dry reforming reaction is given below:

[0010] CH4(s)→CH x (s)+(4-x))H(s) (4)

[0011] CH x(s)→(s)+xH(s) (5)

[0012] H(s)+H(s)→H2(g) (6)

[0013] The pathway for forming carbon from carbon dioxide during the dry reforming reaction is as follows:

[0014] CO2(g)→CO(s)+O(s) (7)

[0015] CO(s)→C(s)+O(s) (8)

[0016] O(s)+O(s)→O2(g) (9)

[0017] O(s)+H(s)→H(s)+H2O(g) (10)

[0018] To date, the implementation of such dry reforming reactions has generally been hampered by carbon formation during the dry reforming reaction. Carbon formation on the surface of the catalyst deactivates the catalyst by forming a carbonate phase, thus requiring frequent regeneration or, in some cases, permanently destroying the active sites. It is desirable to design a reactor for dry reforming of methane with enhanced carbon dioxide fixation. Therefore, a reactor system and process that addresses the above-mentioned problems is desirable.

[0019] The present invention relates to a novel CARGEN (or carbon generator) process (US2020 / 0109050A1, WO2018187213A1) 1 . A unique and highly scalable catalyst preparation recipe for the CARGEN reaction is described herein. The CARGEN reactor comprises two reactors in series, wherein the first reactor is referred to as the CARGEN reactor and the second reactor is referred to as the reformer. The first reactor converts CH4 and CO2 into solid carbon and gaseous products CO, H2, H2O and unconverted CH4 and CO2. The carbon produced by the CARGEN reactor is specifically in the form of multi-walled carbon nanotubes (MWCNTs) and some amorphous and graphitic carbon impurities. The gas produced by the CARGEN reactor is directly processed in the reformer reactor to produce a high concentration mixture with a ratio of CO to H2 that meets downstream applications. Figure 1 Provide a systematic review of the CARGEN process.

[0020] CARGEN technology is a unique advancement in the field of dry reforming of methane (DRM), in which CO2 and CH4 are converted into syngas (a mixture of hydrogen and carbon monoxide) as discussed above. 2 DRM is a heterogeneous reaction, which means it is a catalytic process. In addition, the reaction is severely affected by the formation of solid carbon mainly due to two side reactions:3-5 :

[0021] i) Boudouard reaction, or CO disproportionation reaction: 2CO→CO2+C(11)

[0022] ii) Methane decomposition reaction: CH4→C+2H2 (12)

[0023] The formation of solid carbon leads to catalyst deactivation, since the formed carbon makes the accessibility of the catalyst active sites less accessible and therefore does not allow the reaction to continue for a longer period of time. 6 Catalyst deactivation is particularly a problem in DRM, which significantly hinders its implementation on an industrial scale. The reason behind such peculiar carbon formation behavior in DRM is the unavailability of sufficient oxygen and hydrogen in the reaction gas. 7 The O:C:H ratio in DRM is 1:1:2, whereas in other conventional reforming processes, such as in partial oxidation (POX), it is 1:1:4, and in steam methane reforming (SRM), it is 1:1:6 7 Due to the lack of sufficient hydrogen and oxygen in the reaction gas, the surface carbon cannot react and stays on the surface permanently. During this period, it continues to combine with other surface carbon molecules and form strong CC bonds, thereby forming amorphous or graphite or carbon nanotube type carbon. 6 The type and morphology of surface carbon depends on the type of catalyst material, its surface energy, and the surface sites.

[0024] CNT growth is specifically believed to occur via two different mechanisms: 6,8 : (a) End-growth mechanism - where CNT growth occurs below the catalyst crystal sites and the CNTs are present between the active sites and the support. In this case, the metal-support interaction is not very strong, which allows the active material to move easily through the bed. 9 (b) Base growth mechanism - where CNT growth occurs above catalyst crystal sites and the active catalyst sites are strongly bound to the support surface. The tip growth mechanism is considered the most active (and worst choice) for carbon formation in the DRM process because it allows for bulk carbon formation and accumulation due to weak metal-support interactions. 9 In addition, when the metal-support interaction is weak, the formation of CNTs leads to a continuous change in the surface distribution of active sites on the bed.

[0025] Since the goal of the CARGEN unit is to form CNTs, it is necessary to synthesize catalysts that provide specific features that promote CNT growth. This method of enhancing surface CNT growth is not a desired feature of any methane reforming catalyst; however, it is the most necessary feature for CARGEN catalysts. The idea is to adjust the selectivity of the catalyst to CNTs rather than to syngas. Therefore, catalyst materials that provide basic features for CNT growth (such as metal-support interaction, acidity / basicity of catalyst sites) are useful for the CARGEN process. 9 .

[0026] The inventors have found that the most critical parameter affecting CNT growth is the metal-support interaction 10-14 The weaker the interaction or the looser the active metal bonding, the greater its ability to grow CNTs will be. In addition, the crystallite size also has a huge impact on the size (diameter) of the CNTs, which is a direct result of our microscopic evaluation of various used CARGEN catalyst samples studied to develop the CARGEN catalyst. In addition, this evaluation is also consistent with some previous work 10-17 The tailored CARGEN catalyst presented herein is synthesized in a manner such that it benefits from weak metal-support interactions to allow rapid CNT growth while facilitating great active metal mobility.

[0027] The environmental impact of bulk industrial catalyst synthesis is one of the major decision parameters considered prior to any commercialization plan. This includes consideration of the precursors required as well as the waste generated by the process.

[0028] Conventional catalyst synthesis routes include the following methods 17 :

[0029] i) Incipient wetness impregnation (IWI) method, in which the target active metal is dissolved in an organic or aqueous solution, depending on the type and nature of the active metal: this solution is poured onto a support having a pore volume equal to the volume of the metal solution. Due to capillary action, all the metal solution is sucked into the support pores. If the solution volume exceeds the pore volume, diffusion processes occur, which make the transport of the active metal to the pores much slower. The catalyst slurry is then dried and calcined to eliminate all volatile components in the solution and at the same time precipitate the active metal onto the catalyst support. The limitation is that the loading of the active metal is limited by the solubility of the active metal solution. Therefore, the choice of solution is very critical in this process. On the other hand, the downside of this process is that it produces harmful and toxic volatile compounds after calcination and requires a large amount of solvent to prepare the solution, the weight of the solvent is sometimes even ten times compared to the weight of the catalyst produced. Therefore, this type of catalyst is not environmentally sustainable at all.

[0030] ii) Precipitation, where a precipitate is formed from a homogeneous liquid due to a temperature shift or by a chemical reaction: The chemical reaction can occur due to the addition of an acid or base to an alkaline or acidic solution, respectively. It can also occur due to the addition of a complex coagulant. In almost all processes, nucleation occurs first, or simultaneously with agglomeration. Nucleation refers to the process in which small solid particles begin to form due to a shift. In contrast, agglomeration refers to particle growth due to the formation of new particles or the association of existing particles. Again, this process is not environmentally sustainable due to the large amounts of chemicals involved and the generation of waste.

[0031] iii) Co-precipitation, which is a method generally used for the synthesis of multi-component systems: In this method, macroscopic homogeneity is not easy to obtain, because the composition of the precipitate depends on the solubility differences between the components and the chemical reactions that occur during precipitation. One of the main applications of this process is the synthesis of molecular sieves. Similar to precipitation and IWI methods, this method also involves the use of many solvents and reagents, which can lead to the generation of large amounts of waste and are therefore not environmentally sustainable.

[0032] Other catalyst preparation methods include, for example, sol-gel, hydrothermal, gelation, crystallization, etc., which require large amounts of chemical reagents in amounts that are tens of times greater than the final weight of the synthesized catalyst. 17 While these approaches may prove to be very useful for catalyst synthesis, there are significant environmental concerns in their implementation.

[0033] Therefore, there is a need to identify better catalyst synthesis methods that are more sustainable and at the same time scalable. More importantly, if the goal of the entire process (such as DRM or CARGEN) is to improve sustainability and reduce carbon emissions, the role of green catalysts and sustainable methods becomes very important.

[0034] The traditional ball milling process used for catalyst synthesis is a grinding method in which solids are ground together into a very fine powder. 14 During this process, extremely high local pressures are formed at the rigid ball collision points. These collision balls are made of ceramic, flint and stainless steel. The grinding time, the rpm of the rotating container, the size of the balls and the ratio of the sample weight to the number of balls are some of the important control parameters. In addition to the benefits of ultrafine grinding, a second advantage of ball milling is the homogenization of the solid mixture, which is very difficult to achieve.

[0035] The production of CNTs from methane decomposition and other catalytic hydrocarbon cracking processes forms a closely related group of research to the CARGEN process. Although both processes produce various forms of carbon nanotubes, the important difference between the CARGEN process and previous methods lies in the basic goal and principle of operation for producing synthesis gas from greenhouse gases CO2 and CH4. As mentioned earlier, the CARGEN reactor can be considered as a conditioning block for processing the feed to the reformer so that the final synthesis gas ratio (H2:CO) meets the downstream applications (such as methanol production, Fischer-Tropsch synthesis, etc.).

[0036] KR20110092274 A discloses a catalyst comprising cobalt and molybdenum in a ratio of 1:0 to 2:3. Applicable processes involve cracking of methane, ethylene and acetylene.

[0037] US4663230A discloses a catalyst comprising particles containing iron, cobalt or nickel, the diameter of the particles being between about 3.5 and about 70 nanometers. Suitable processes involve methane, ethane, propane, ethylene, propylene or acetylene or mixtures thereof.

[0038] US6333016B1 discloses a catalyst containing at least one metal from Group VIII, including, for example, Co, Ni, Ru, Rh, Pd, Ir and Pt; and at least one metal from Group VIb, including, for example, Mo, W and Cr. Applicable processes involve a carbonaceous gas selected from the group consisting of saturated hydrocarbons, aliphatic hydrocarbons, oxygenated hydrocarbons, aromatic hydrocarbons, carbon monoxide and mixtures thereof.

[0039] JP4068056B2 discloses a catalyst supported on hydroxide and / or carbonate or a mixture thereof, the catalyst comprising a nanoparticle dispersion of a metal in any oxidation state, the metal being Fe, Co, Ni, V, Cu, Mo, Sn and / or a catalyst system selected from a group consisting of a mixture. The catalyst system carrier is made of CaCO3, MgCO3, Al2(CO3)3, Ce2(CO3)3, Ti(CO3)2, La2(CO3)3 and / or a mixture thereof. Applicable processes relate to the catalytic cracking of acetylene, ethylene, butane, propane, ethane, methane or any other gas or volatile carbon-containing compound.

[0040] AU2004234395A1 discloses a catalyst, the catalyst being a carbon nanotube-ceramic composite comprising metal catalytic particles, the metal catalytic particles comprising at least one of Co, Ni, Ru, Rh, Pd, Ir, Pt, at least one Vlb group metal and a support material, the substances being combined to have a particulate form. Applicable processes involve a carbon-containing gas selected from the group consisting of saturated hydrocarbons, aliphatic hydrocarbons, oxygenated hydrocarbons, aromatic hydrocarbons, alcohols, carbon monoxide and mixtures thereof.

[0041] US7628974B2 discloses a catalyst comprising at least one member selected from the group consisting of Fe, Mo, Co, Ni, Ti, Cr, Ru, Mn, Re, Rh, Pd, V and alloys thereof. Applicable processes involve the cracking of hydrocarbons, not limited to aliphatic hydrocarbons, aromatic hydrocarbons, carbonyls, halogenated hydrocarbons, silylated hydrocarbons, alcohols, ethers, aldehydes, ketones, acids, phenols, esters, amines, alkyl nitriles, sulfides, cyanates, nitroalkyls, alkyl nitrites and / or mixtures of one or more of the above, and more generally methane, ethane, propane, butane, ethylene, acetylene, carbon monoxide, benzene and methylsilane.

[0042] US6849245B2 discloses a catalyst material comprising a Group VIII metal (Fe, Ni, Co) and possibly mixed with Group IB metals such as Cu, Ag and Au. Applicable processes involve carbon-containing compounds selected from CO, methane, ethane, ethylene, acetylene, propane, propylene, butane, butene, butadiene, pentane, etc.

[0043] US20050025695A1 discloses a metal oxide catalyst selected from metals including iron, nickel, cobalt, lanthanum, gold, silver, molybdenum, iron-nickel alloy, iron-copper alloy and alloys thereof. Applicable processes relate to flame synthesis methods for converting a mixture of CO and H2 into carbon nanostructures and selected "carbonaceous raw materials".

[0044] US20050232843A1 discloses a metal selected from the group consisting of platinum, palladium, nickel, iron, cobalt, ruthenium, tungsten and molybdenum. Suitable processes involve methods involving heating a solution vapor of components in an atmosphere containing carbon, oxygen, hydrogen and sulfur as saturated vapor of the solution.

[0045] US9409779B2 discloses a heterogeneous catalyst comprising Mn, Co, preferably also molybdenum and an inert support material, as well as the catalyst and carbon nanotubes themselves and their uses. Applicable processes relate to the catalytic cracking of light hydrocarbons (such as aliphatic and olefinic). However, alcohols, carbon oxides (especially CO), aromatic compounds with and without heteroatoms, and functionalized hydrocarbons (such as aldehydes or ketones) can also be used, as long as these substances decompose on the catalyst. Other selected hydrocarbons are listed in the patent literature. BRIEF DESCRIPTION OF THE DRAWINGS

[0046] The features and advantages of the invention described herein may be better understood with reference to the accompanying drawings, in which:

[0047] Figure 1 This is a systematic review of the CARGEN process.

[0048] Figure 2 The weight gain curve from a thermogravimetric analysis (TGA) experiment of the CARGEN catalyst is shown.

[0049] Figure 3 The linear plot of N2 physical adsorption isotherm of fresh catalyst samples prepared in Examples is shown.

[0050] Figure 4 The temperature programmed reduction (TPR) curves of the fresh catalyst samples prepared in the examples are shown.

[0051] Figure 5 X-ray diffractometer (XRD) curves of fresh and reduced catalyst samples in the examples are shown.

[0052] Figure 6 is a scanning electron microscope (SEM) image of the CARGEN catalyst used in the examples.

[0053] Figure 7 The transmission electron microscope (TEM) image of the CARGEN catalyst in the example. Summary of the invention

[0054] In a general embodiment, the present disclosure provides a method of preparing a catalyst for use in a CARGEN process, the method comprising milling a transition metal oxide, wherein the catalyst is supported or unsupported.

[0055] In one embodiment, the transition metal oxide may comprise nickel oxide.

[0056] In one embodiment, the catalyst is supported by a support material which may comprise alumina.

[0057] In one embodiment, the catalyst may comprise alumina.

[0058] In one embodiment, the amount of transition metal oxide may be about 20 wt % of the total amount of transition metal oxide and support.

[0059] In one embodiment, the transition metal oxide and the support can be milled in a ball milling apparatus.

[0060] In one embodiment, the ball milling apparatus may comprise stainless steel balls of 5 mm diameter.

[0061] In one embodiment, the method can include milling the transition metal oxide and the support for about 1 hour.

[0062] In one embodiment, the method can include mixing the transition metal oxide with the support prior to milling, and milling to produce a solid mixture of the transition metal oxide and the support.

[0063] In one embodiment, the method may include reducing the milled transition metal oxide with a reducing gas.

[0064] In one embodiment, the reducing gas may comprise hydrogen.

[0065] In one embodiment, the ratio of the number of balls in the ball mill to the weight of the catalyst in grams may be from about 1:1 to about 100:1.

[0066] In one embodiment, the ratio of the number of balls in the ball mill to the weight of the catalyst in grams may be from about 1:1 to about 10:1.

[0067] In one embodiment, the ratio of the number of balls in the ball mill to the weight of the catalyst in grams may be from about 10:1 to about 100:1.

[0068] In one embodiment, the ratio of the number of balls in the ball mill to the weight of the catalyst in grams may be about 10:1.

[0069] In one embodiment, the catalyst may have a 2 / g total surface area.

[0070] In one embodiment, the catalyst may have a 3 / g pore volume.

[0071] Another embodiment provides a method of using the prepared catalyst in a CARGEN process.

[0072] In one embodiment, a method for preparing a catalyst for a carbon generation reactor (CARGEN) process is provided. The method includes grinding a precursor material, wherein the catalyst is supported or unsupported. In one embodiment, the precursor material includes at least one of Fe, Ni, Co, Pt, Ru, Mo, lanthanides, etc. Lanthanides may include, for example, Ce, Pr, Nd, Pm, Sm, Eu, Gd, Tb, Dy, Ho, Er, Tm, Yb, Lu, etc.

[0073] Additional features and advantages are described herein and are demonstrated by the following Detailed Description. DETAILED DESCRIPTION

[0074] The present disclosure provides high conversion and high carbon yield CARGEN catalysts, methods for preparing the same, and uses thereof for CARGEN. The disclosed catalysts are inexpensive, but highly effective and suitable for use in the CARGEN process disclosed in WO2018187213, which is fully incorporated herein by reference.

[0075] Specifically, a highly active reforming catalyst customized for the CARGEN process is presented. The catalyst is specially designed to form multi-walled carbon nanotubes (MWCNTs) according to the conditions specified in the inventor's previous patent application US2020 / 0109050 (which is also fully incorporated herein by reference) and WO2018187213. The catalyst is synthesized via ball milling technology to provide a unique active metal-support interaction that is beneficial to the formation of MWCNTs in the CARGEN process. The catalyst is suitable for use in packed bed, chemical vapor deposition (CVD), and fluidized bed operating modes, while the main task of the catalyst is to convert natural gas and carbon dioxide into MWCNTs and synthesis gas and water.

[0076] The CARGEN catalysts of the present invention are prepared using a unique catalyst synthesis technique involving the use of a conventional ball mill. Since the ball milling process is a unit operation that can be performed using electricity, very little waste is generated from such a process.

[0077] CARGEN is the first reactor in a dual reactor system that enables increased carbon dioxide utilization in chemical and fuel processes while ensuring CO2 fixation; the amount of CO2 utilized is less than the amount produced during the process. The first reactor converts CH4 and CO2 into solid carbon, while the second reactor converts CH4 and CO2 into synthesis gas using a combined reforming reaction process. In view of global concerns about greenhouse gas emissions, unlike conventional single-reactor reformer systems, such dual reactor systems enhance total CO2 fixation. From a CO2 life cycle assessment (LCA) and process integration perspective, this system facilitates CO2 utilization in methane reforming under fixed conditions, while producing both solid carbon and synthesis gas. The latter (synthesis gas) is an important raw material for the preparation of a variety of value-added chemicals as well as ultra-clean liquid fuels.

[0078] The combined reforming process aims to react methane (or any other volatile organic compound) with CO2 and optionally other oxidants (such as O2, H2O or both) to produce synthesis gas. The optimal operating conditions of temperature and pressure of the two reactors can be determined using thermodynamic equilibrium analysis. Assuming that the process-related obstacles are solved through the development of efficient catalysts and reactor orientation, any thermodynamically feasible reaction indicates that the reaction can proceed.

[0079] CARGEN is designed to maximize CO2 fixation by optimizing operating conditions, which can maximize carbon formation in the first reactor in the presence of limited oxygen to drive the reaction self-heating. Because partial combustion or partial oxidation reactions are exothermic reactions, the CARGEN reactor performs two main reactions involved in CO2 fixation. The first reaction involves the conversion of CO2 into carbon. The second reaction involves a partial oxidation reaction that uses a portion of methane (or any other volatile organic compound) for partial combustion to produce energy and other products. The energy provided by the partial oxidation reaction is more efficient than any other form of heat transfer because this energy is generated in situ in the process itself.

[0080] The CARGEN reactor can be operated at low temperature and low / high pressure conditions, while the combined reformer (second reactor) can be operated at high temperature and low / high pressure conditions. By taking advantage of the pressure and temperature swings between the two reactor units, improvements are made in both CO2 fixation and the reduction of the total energy demand of the dual reactor setup. The CARGEN process utilizes the work and energy extraction processes (such as turbines, expanders, etc.) associated with the pressure changes between the two reactors to at least partially overcome the pre-compression burden on the feed gas. Therefore, the obvious unique synergy between the two reactors is beneficial to saving carbon credits and improving the sustainability of the overall synergy. In addition to the synthesis gas produced from the second reactor (reforming reactor), the CARGEN process also produces solid carbon or carbonaceous materials from the first reactor (CARGEN reactor). This carbonaceous product produced as part of the CO2 fixation process has industrial value. Specifically, the carbonaceous product can serve as a starting material to prepare many value-added chemicals, thereby generating a large amount of revenue for the processing plant. Non-limiting examples of valuable chemicals include activated carbon, carbon black, carbon fiber, different grades of graphite, ceramic materials, etc. This material can also be added to building materials such as cement and concrete, as well as to road tar or wax formulations as part of the overall CO2 capture process.

[0081] The CARGEN process includes a dry reforming process for converting carbon dioxide into synthesis gas and carbon. The CARGEN process uses a dual reactor setup or system to enhance CO2 fixation. The reaction scheme is divided into two processes in separate reactors in series. The first reaction is intended to capture CO2 in the form of solid carbon, while the other reaction is used to convert CO2 into synthesis gas. The present subject matter provides a system method for CO2 fixation.

[0082] In the first reactor of a dual reactor setup, there can be significant conversion of CO2 to carbon under autothermal low temperature conditions (<773.15K). The subsequent removal of solid carbon from the system (first reactor) enhances the conversion of CO2 to syngas in the second reactor by thermodynamically driving the reaction forward. Thus, carbon is removed from the system, which is very beneficial from a CO2 life cycle assessment (LCA) point of view.

[0083] After the reaction in the first reactor, solid carbon is filtered. The remaining product gas is fed to the second reactor (combined reformer) of the higher temperature that mainly produces high-quality synthesis gas. Thermodynamic analysis of the result of operating the second reactor shows that there is no carbon formation. Compared with the conventional reformer arrangement, this drives the reaction to be carried out at a much lower energy requirement (less about 50kJ) and at a relatively lower temperature. It is also observed that a substantial increase in the synthesis gas yield ratio is not only beneficial to the synthesis gas preparation in the Fischer-Tropsch synthesis (needing about 2:1 H2:CO ratio), but also beneficial to hydrogen preparation (which requires high H2:CO ratio).

[0084] In addition to the advantage of obtaining a higher H2:CO ratio, a significant increase in methane and carbon dioxide conversion is observed at much lower operating temperatures. If a conventional reforming setup is used, such effects will only be obtained at higher temperatures (almost 250°C). The advantage of removing carbon in the first reformer helps to significantly reduce the operating temperature in the second reactor. Thus, the CARGEN process is much more energy efficient than a conventional single reactor setup operating at higher temperatures to obtain similar levels of methane and carbon dioxide conversion with zero carbon deposition.

[0085] In addition to the advantage of obtaining a higher H2:CO ratio, a significant increase in methane and carbon dioxide conversion is observed at much lower operating temperatures. If a conventional reforming setup is used, such effects will only be obtained at higher temperatures (almost 250°C). The advantage of removing carbon in the first reformer helps to significantly reduce the operating temperature in the second reactor. Thus, the subject matter of the present invention has much higher energy efficiency for obtaining similar levels of methane and carbon dioxide conversion with zero carbon deposition compared to a conventional single reactor setup operating at higher temperatures.

[0086] In the process of the present invention, by co-feeding methane and / or oxygen and / or steam to the first reactor together or separately, carbon dioxide is partially utilized in the first reactor, thereby producing only solid carbon as a product. The operating conditions of the CARGEN reactor are selected so that they promote the production of solid carbon without promoting the production of synthesis gas. Therefore, the second reactor (modified reforming reactor) aims to produce synthesis gas from the feed gas (mainly unconverted methane, carbon dioxide, steam, etc.) leaving the CARGEN reactor.

[0087] From the viewpoint of energy utilization and efficiency, the CARGEN process creates an environment conducive to the production of a single product in two separate reactors. In addition, the inventive process can use relatively inexpensive catalysts (e.g., naturally occurring minerals such as lime dolomite, coal, etc.) in the first reactor (CARGEN) to help improve carbon formation. Since the carbon dioxide concentration from the first reactor is significantly reduced, the carbon formation tendency of the second reactor is almost eliminated. Therefore, a way is opened up to use expensive, high stability and high resistance catalysts on the stream for longer operating run times.

[0088] In addition, the CARGEN process provides a unique opportunity to dispose of the two products separately due to the unique method of separating the operating conditions in two different reactors. For example, when the first reactor (CARGEN) is under maintenance, the second reactor (which is mainly carbon-free) does not need to undergo maintenance. During such situations, more than one CARGEN reactor can be added in parallel to ensure continuous operation.

[0089] Additionally, the catalyst removal methods in the first reactor and the second reactor will be different because the second reactor may use a more expensive catalyst and not require as many maintenance cycles, but may undergo regeneration more frequently. On the other hand, the first reactor may require many maintenance cycles and less frequent catalyst regeneration. The difference in catalyst disposal methods and operating conditions for the separate production of two products makes the CARGEN process unique when compared to conventional systems and methods.

[0090] The remaining reaction gas mixture can be used in a reforming reaction in a separate second reactor in order to perform a dry reforming reaction while discarding the sacrificial surface (catalyst) in the CARGEN.

[0091] Inexpensive or sacrificial catalyst materials can be discarded in a batch process while new materials are loaded. CARGEN can be used for carbon capture while using regenerated catalyst from a separate regenerator operating in parallel mode. The sacrificial surface (catalyst) can be treated alone to at least partially recover the catalyst while removing solids (including carbon and sacrificial materials).

[0092] The CARGEN can optionally be operated without the use of additional steam, since adding steam both increases energy requirements and reduces coke formation. However, steam can be added to the second reformer (also referred to as operating in a combined dry / steam reforming format) to increase methane conversion.

[0093] Adding oxygen to both the CARGEN and / or the combined reformer improves carbon capture performance as it increases carbon formation in the CARGEN and reduces the overall energy requirements of the dual reactor setup.

[0094] Removing carbon from the CARGEN (either mechanically or using spent catalyst) pushes the reforming reaction in the second reactor (combined reformer) forward and thus subsequently significantly increases the overall CO2 and methane conversion to syngas.

[0095] Steam can be added to the second reactor to produce a hydrogen-rich syngas for the production of hydrogen. The use of steam in the second reactor significantly increases the amount of hydrogen in the system.

[0096] The product gas mixture from the second reactor can be used at least as a feedstock for the production of hydrogen, as a feedstock for the Fischer-Tropsch synthesis reaction, and as a feedstock for use as an energy source in a hydrogen-based fuel cell. The reaction gas can be an output product in a process plant furnace and can be a combination of flue gas and / or carbon dioxide and unreacted methane.

[0097] The CARGEN reactor can be operated under autothermal conditions by using oxygen as an additive for partial combustion (or oxidation) as an energy source. Autothermal low temperatures (below 773K) are associated with zero carbon credits and therefore have a greater impact in the fixation of CO2 from the life cycle of the process plant. The CARGEN reactor can be operated under low temperature and low / high pressure conditions, while the second reactor can be operated under high temperature and low / high pressure conditions.

[0098] The first reactor (CARGEN reactor) comprises a mechanical housing facility for receiving methane, carbon dioxide and at least one or more oxidants (oxygen, etc.). The first reactor may also include a housing / mechanical device to initiate the removal and reloading of sacrificial catalytic materials (new batches or regenerated batches) for carbon capture. The carbon captured on the sacrificial catalyst material can be partially or completely recovered based on a cost-benefit analysis.

[0099] A pretreatment process may be incorporated between the two reactors, comprising heating, cyclone separation, and mixing of additional oxidant (oxygen or steam or both with the gas leaving the CARGEN) in the second combined reformer. In such a process, the catalyst selected is compatible with the combined reforming reaction in the second reactor.

[0100] The pressure swing between the two reactors, where the pressure is high in the first reactor and lower in the second reactor, can significantly affect the carbon formation and energy requirements in the entire system. The pressure swing between the two reactors, where the pressure is lower in the first reactor and higher in the second reactor, significantly reduces the net energy requirement, but reduces the overall CO2 conversion rate %.

[0101] Without adding steam to both reactors, the first reactor can be operated under autothermal conditions (by adding pure oxygen along with CO2 and methane) at a higher pressure than the second reactor. However, if desired (for hydrogen production, etc.), steam can be added only to increase the hydrogen content of the product synthesis gas.

[0102] Pressure swings between reactors can be achieved by using expander units, which reduce the pressure while producing high quality shaft work that can be used elsewhere in the plant. Pressure swings between reactors can also be achieved by using turbine generator units, which reduce the pressure while producing high quality shaft work that can be used elsewhere in the plant.

[0103] The carbon dioxide capture process may be switched back and forth for continuous operation during cycles of maintenance and operation by at least one additional gear set.

[0104] The regeneration process may be performed by using any potentially volatile organic compound such as ethanol, methanol, glycerol, etc. instead of methane or any such combination.

[0105] Furthermore, the CARGEN reactor can be configured to produce individual carbonaceous compounds from the CARGEN process in the form of carbon dioxide fixation. This can be relevant to the industrial production of black ink for printing presses and to the industrial production of different grades of graphite that can be used to make different grades of cast iron / steel or batteries.

[0106] Furthermore, the energy utilization of the regeneration process can be extremely low (almost 50%) compared to prior art techniques.The CARGEN process also has the benefit of high efficiency, as the CARGEN process has the ability to convert over 65% of the CO2 per reactor pass.

[0107] The disclosed catalysts may comprise transition metals which may be supported or unsupported. The preparation method involves mixing the oxide of the transition metal with or without a suitable support in a standard ball milling apparatus to produce a fine and homogeneous solid mixture of the transition metal oxide and the support.

[0108] The disclosed catalyst provides a surface for reactions in which reactant gases including methane, CO2, H2O and / or O2 can react. The particular utility of this catalyst is directed to the CARGEN process for producing high quality carbon materials from greenhouse gases. This process can be useful industrially because it presents an inexpensive and scalable method for preparing large quantities of catalysts for use in the CARGEN process.

[0109] The CARGEN process is a unique technology in the field of CO2 conversion technology. This catalyst is particularly suitable for the CARGEN process. The catalyst presented in this disclosure is aimed at forming carbon from the reaction gas via the CARGEN process.

[0110] In some embodiments, this catalyst can be prepared as follows:

[0111] 1. Prepare or obtain transition metal oxides and suitable carriers;

[0112] 2. mixing the transition metal oxide and the support in a suitable ratio, wherein the transition metal oxide accounts for 0% to 100% of the total batch weight;

[0113] 3. Mixing the transition metal oxide with the support using a standard ball milling process for a suitable time, which is optimized based on the total weight of the batch being prepared;

[0114] 4. The number of balls used in the ball milling process can be set in such a way that the ratio of the number of balls to the weight of the catalyst in grams can be about 10:1, and a variable ratio in the range of 1:1 to 100:1 can also be used as required by the process;

[0115] 5. The final mixture of supported catalysts can be reduced using a suitable reducing gas, such as hydrogen, and used in the CARGEN process to produce high quality carbon materials from greenhouse gases.

[0116] These steps do not need to be followed in an exact order and are interchangeable. This process is highly scalable and can be easily performed on a commercial scale using standard ball milling techniques.

[0117] The inventors performed controlled experiments for catalyst preparation and ran the experiments under CARGEN specified conditions.

[0118] In a non-limiting example, the inventors prepared a 20 wt % nickel oxide catalyst supported by alumina using the procedure described above. The catalyst was prepared in a ball milling apparatus using 5 mm diameter stainless steel balls. A total of 2 g of catalyst was produced, for which a mixture was prepared using such balls. Ball milling was performed for 1 hour, and then the resulting catalyst was subjected to material characterization.

[0119] The inventors also performed the following material characterization of the fresh catalyst to determine the characteristics of this catalyst:

[0120] 1. XRD analysis was performed to determine the crystal structure of the catalyst. As indicated by the presence of sharp peaks in the XRD curve, it revealed the presence of nickel oxide and aluminum oxide.

[0121] 2. Brunnauer Emmet and Teller (BET) surface area analysis was performed to determine the surface area of ​​the catalyst. It showed that the catalyst had a surface area of ​​101 m 2 This indicates that this process produces extremely high surface area catalysts.

[0122] 3. The BJH pore volume of the catalyst was determined and the results showed that the pore volume was at least 0.1 cm per gram of catalyst. 3 .

[0123] 4. Temperature programmed reduction (TPR) analysis was performed to test the reducibility peak of the catalyst material. A TPR curve was generated when the temperature was gradually increased on a catalyst sample placed in a U-tube under hydrogen flow in a standard chemical adsorption apparatus. The generated TPR curve had the characteristics of a nickel material, which also indicated that the active material was easily reduced and corresponded to pure nickel.

[0124] The inventors also performed the following proof-of-concept experiments, which showed that this catalyst works:

[0125] 1. Proof of concept analysis was performed using a standard Thermogravimetric Analyzer (TGA) instrument. The weight gain curve was analyzed based on the reaction occurring on the crucible plate of the instrument.

[0126] 2. A reaction gas containing methane, carbon dioxide and oxygen in the ratio specified by the CARGEN process was passed through a TGA apparatus at a temperature of 550°C and the weight increase on the apparatus crucible plate was monitored.

[0127] 3. Along with the weight gain, the inventors also monitored the evolved gases and their concentrations using a standard residual gas analyzer (RGA) device. The RGA data showed that the evolved gases contained hydrogen, carbon monoxide, water, and unreacted gases. This indicated that a reaction had occurred and that the weight gain was due to carbon formation.

[0128] After this experiment, the inventors conducted the following characterization studies on the spent catalyst material:

[0129] 1. SEM was performed to identify the structure and type of material formed during the experiment. Carbon nanotubes were observed to have different diameters ranging from a few nanometers to hundreds of nanometers. In addition, the length of the nanotubes ranged from a few nanometers to micrometers, which clearly indicated the formation of carbon nanotubes.

[0130] 2. Energy dispersive X-ray (EDX) analysis was performed to test the material surface and its weight concentration. The EDX curve showed that the surface contained only carbon, nickel and aluminum oxide particles, which clearly showed that carbon material was formed in the CARGEN process.

[0131] Example

[0132] Example 1: Ball-milled CARGEN catalyst synthesis

[0133] i) Nickel oxide particles with a size ranging from 50 to 500 μm were prepared using conventional techniques, which may include calcination of nickel nitrate and the like.

[0134] ii) An alumina support available from any standard catalyst supplier (SASOL Purolox, Alpha Aesar, Sigma Aldrich, etc.) is mixed with nickel oxide particles in a ratio to produce 20% Ni / Al2O3.

[0135] If 1 g of catalyst needs to be prepared, 0.253 g of NiO is mixed with 0.8 g of Al2O3. The extra 0.053 g of NiO is due to the presence of oxygen in the form of NiO, as our ultimate goal is to produce Ni instead of NiO.

[0136] iii) The catalyst mixture and the balls are loaded into a ball milling container. In this experiment, a Retsch (R) CRYOMILL device was used. The parameters set in this experiment were as follows: rotation speed: 50 Hz, 250 rpm, sample weight (g): ball number ratio = 1:10, ball mass = 0.5 g, grinding time: 1 hour.

[0137] iv) After 1 hour of grinding time, the catalyst mixture was calcined at 400°C for 4 hours to remove moisture and any other volatile compounds that may be present in the catalyst mixture. During calcination, the muffle furnace was set to reach a target of 400°C at a ramp rate of 5°C / min, then maintained for 240 minutes and then slowly ramped down to room temperature.

[0138] v) After calcination, the sample was sieved in the 300 μm size range. It was observed that all particles passed through the sieve, indicating that the average particle size was below 300 μm.

[0139] Example 2: Thermogravimetric analysis (TGA) experiment:

[0140] TGA analysis was performed for weight gain testing and proof of concept studies of the CARGEN process. In this analysis, the TGA / SDT Q600 equipment.

[0141] i) Take 20 mg of freshly calcined catalyst batch and place in the sample alumina crucible of the TGA apparatus. An empty reference alumina crucible of the same weight is kept on a second weighing pan of the crucible to eliminate any weight fluctuations caused by temperature increase during the experiment.

[0142] ii) Next, the weighing pan is tared to record a zero weight value. A reduction protocol is initiated, the reduction protocol comprising the following steps:

[0143] a) drying at 150°C for 2 hours;

[0144] b) The temperature was gradually increased at a rate of 5°C / min to a target temperature of 800°C and then maintained for 2 hours. After the reduction was complete, the TGA temperature was gradually decreased to 550°C, which is the desired CARGEN reaction temperature.

[0145] c) A CARGEN reaction gas containing O2, CO2 and CH4 in a ratio of 0.1 / 0.6 / 1 was fed to the TGA reactor to start the reaction. The weight gain curve of this experiment is Figure 2 Shown in.

[0146] Example 3: Characterization

[0147] i) Fresh Catalyst Physical Adsorption: Physical adsorption data of fresh catalyst samples were obtained from a standard Tri-star II Micromeritics instrument. Table 1 reports the BET surface area and Barrett-Joyner-Halenda (BJH) pore volume data, while the adsorption / desorption isotherm linear plots are given in Figure 3 Available in.

[0148] The fresh catalyst exhibited a Type IV isotherm with a HI type hysteresis loop. The BET results indicated that the catalyst particles were mesoporous and spherical in nature with uniform size and shape.

[0149] Table 1 Physical adsorption data of fresh novel CARGEN catalysts

[0150]

[0151] ii) Fresh catalyst chemisorption: To find the most suitable reduction temperature conditions for freshly prepared catalysts, temperature programmed reduction (TPR) experiments were performed in a standard Autochem-II Micromeritics chemisorption apparatus. The TPR graph based on the thermal conductivity change signal is presented in Figure 4In the experiment, the catalyst was reducible. A strong TCD peak was observed to form at a temperature of 498°C, indicating that the material was reducible at temperatures above 498°C. The reducibility of the catalyst was calculated using the hydrogen consumption in the H2-TPR experiment. It was found that the actual H2 uptake was 2287 micromoles per gram of catalyst at STP. According to theoretical calculations, the H2 uptake of the catalyst at STP was found to be 3412 micromoles per gram of catalyst. Therefore, the degree of reduction of the catalyst was 67%. It is also worth noting that, as reported in many literatures, Ni supported on γ-Al2O3 exhibits two unique reduction temperatures between 350-900°C. 14,18 This is due to the fact that strong metal-support interactions increase the reduction temperature of bulk Ni2O3 and also increase the formation of difficult-to-reduce NiO due to strong interactions with the support. In the catalyst of the present invention, only one reduction peak of Ni was observed around 498°C, indicating the formation of a weak support-metal interaction (SMI) intended for the CNT tip growth mechanism. TPR results further show that the catalyst thus forms an eggshell structure. 14 .

[0152] iii) XRD studies: XRD analysis of fresh and reduced samples was performed using a Rigaku Ultima IV diffractometer with Cu (Kα) radiation (40 kV / 40 mA). Both samples were loaded separately and recorded in the 2θ range of 20-110° with a step size of 0.02° or an interval of 2 s. Figure 5 Stacked XRD patterns of fresh and reduced samples are presented. It can be clearly seen that all the peaks in the fresh sample are related to NiO and Al2O3 catalysts, while in the reduced sample, most of them have been converted to Ni as noticed by the peak shift. The crystallite size of the fresh and reduced catalyst samples in Ni(012) and Ni(111) planes was calculated using the Scherrer equation. Ni was observed after reduction with H2 0 Slight (1.5X) sintering of the particles, as the crystallite size of the reduced sample increased from 21.4 nm of the fresh sample to 35 nm. Sintering due to coalescence is a well-established phenomenon that allows Ni 0 The crystallites migrate on the support surface due to the reduction at a higher temperature and form crystallites of larger size. 0 The polymerization is an exothermic reaction, which also promotes the sintering of microcrystals.

[0153] iv) Microscopy evaluation: To verify the formation of carbon and in particular MWCNTs, the spent catalyst from the TGA analysis was analyzed under SEM and TEM. Figure 6 and Figure 7Some of the selected images from SEM and TEM microscopy studies are presented respectively. SEM and TEM microscopy results indicate the formation of MWCNTs with diameters ranging up to 100 nm and lengths in the micrometer range.

[0154] In summary, a CARGEN reaction catalyst is presented together with its preparation procedure. The present invention discloses the following:

[0155] A nickel-based catalyst is used in a CARGEN reactor.

[0156] The nickel-based catalyst may be a supported or unsupported catalyst.

[0157] The support material may comprise alumina, titania, silica, zeolites, carbon, or any other suitable support material useful in a CARGEN reaction.

[0158] The nickel-based catalyst comprises at least 1 wt % nickel up to 100 wt % nickel.

[0159] The support material may be activated carbon, carbon nanotubes or carbon nanofibers, which may be produced separately from the CARGEN process itself.

[0160] Carbon support materials are commercially available but have a purity of at least 90%.

[0161] A ball milling apparatus may be used to mix the catalyst and the support.

[0162] The ball milling equipment also increases the surface area of ​​the catalyst while reducing its particle size.

[0163] The ball milling equipment can be laboratory scale equipment or bench scale or pilot scale or industrial scale. All scales provide similar quality of catalyst material.

[0164] The catalyst produced by the above ball milling equipment can be produced on laboratory scale, pilot scale and industrial scale.

[0165] All the features mentioned above are also applicable to the preparation of other catalysts for CARGEN using Group VIII metals such as Fe, Ni or Co and combinations thereof.

[0166] The above-mentioned catalyst materials can be prepared using other supporting materials, including but not limited to SiO2, TiO2, Al2O3, MgO, ZrO2, CeO2, zeolite, metal organic framework (MOF), inorganic clay, carbonate, carbon nanotubes, etc.

[0167] The catalyst material used for CARGEN as described above may form an eggshell structure similar to a weak SMI as may be required for MWCNT growth. However, the catalyst material may not be specifically limited to an eggshell structure.

[0168] The diameter of MWCNTs from the above catalyst materials may range up to 100 nm. However, some of the MWCNTs may also form sizes above 100 nm.

[0169] As used herein and in the claims, the singular form of a word includes the plural unless the context clearly indicates otherwise. Thus, references to "a," "an," and "the" generally include plural forms of the respective terms. For example, references to "an ingredient" or "a method" include a plurality of such "ingredients" or "methods." The term "and / or" used in the context of "X and / or Y" should be interpreted as "X" or "Y" or "X and Y."

[0170] Similarly, the word "comprising" should be interpreted as inclusively rather than exclusively. Likewise, the terms "including" and "or" should all be understood as inclusive, unless such a structure is explicitly prohibited by the context. However, the embodiments provided by the present disclosure may lack any element not specifically disclosed herein. Therefore, the embodiments identified by the public use of the term "comprising" are also embodiments that disclose "essentially consisting of the disclosed components" and "consisting of the disclosed components". When used in this article, the term "example", especially when a number of items are listed later, is only exemplary and illustrative, and should not be considered exclusive or comprehensive. Unless otherwise explicitly indicated, any embodiment disclosed herein may be combined with any other embodiment disclosed herein.

[0171] It should be understood that various changes and modifications to the currently preferred embodiments described herein will be apparent to those skilled in the art. Such changes and modifications may be made without departing from the spirit and scope of the subject matter of the present invention and without reducing its expected advantages. Therefore, such changes and modifications are intended to be covered by the claims.

[0172] References cited:

[0173] 1. Elbashir NO, Challiwala MS, Sengupta D, El-Halwagi MM. System and method for carbon and syngas production. PropertyWI, Organization, eds. 2018.

[0174] 2. Pakhare D, Spivey J. A review of dry (CO2) reforming of methane over noble metal catalysts. Chem Soc Rev. 2014; 43(22): 7813-7837. doi: 10.1039 / c3cs60395d

[0175] 3. Chatla A, Ghouri MM, Elbashir NO. Highly stable Copper-Nickel alloyed catalyst for CO2 reforming of Methane: Theory guided experimental validation catalyst design. 2019.

[0176] 4. Tavares MT, Alstrup I, Bernardo CA, Rostrup-Nielsen JR. Carbon Formation and CO Methanation on Silica-Supported Nickel and Nickel-Copper Catalysts in CO + H2 Mixtures. J Catal. 1996; 158 (2): 402-410.

[0177] 5. Snoeck JW, Froment GF, Fowles M. Kinetic study of the carbon filament formation by methane cracking on anickel catalyst. J Catal. 1997; 169(1): 250-262.

[0178] 6. Gili A, Schlicker L, Bekheet MF, et al. Surface carbon as active intermediate in dry reforming of methane to syngas on a 5% Ni / MnO catalyst. ACS Catal. 2018; 8(9): 8739-8750.

[0179] 7. Challiwala M, Afzal S, Choudhury HA, Sengupta D, El-halwagi M, Elbashir NO. Alternative pathways for CO2 utilization for enhanced methane dry reforming technology. Published in: Advances in Carbon Management Technologies.; 2019.

[0180] 8. Amelinckx S, Zhang XB, Bernaerts D, Zhang XF, Ivanov V, Nagy JB. A formation mechanism for catalytically grown helix-shaped graphite nanotubes. Science (80-). 1994; 265(5172): 635-639.

[0181] 9. Dupuis AC. The catalyst in the CCVD of carbon nanotubes—a review. Prog Mater Sci. 2005; 50(8): 929-961.

[0182] 10. Yeoh WM, Lee KY, Chai SP, Lee KT, Mbhamed AR. Effective synthesis of carbon nanotubes via catalytic decomposition of methane: Influence of calcination temperature on metal-support interaction of Co-Mo / MgO catalyst. J Phys Chem Solids. 2013; 74(11): 1553-1559.

[0183] 11. Cheung CL, Kurtz A, Park H, Lieber CM. Diameter-controlled synthesis of carbon nanotubes. J Phys Chem B. 2002; 106(10): 2429-2433.

[0184] 12. Kumar M, Ando Y. Controlling the diameter distribution of carbon nanotubes grown from camphoron a zeolite support. Carbon N Y. 2005; 43(3): 533-540.

[0185] 13. Huh Y, Green MLH, Kim YH, Lee JY, Lee CJ. Control of carbon nanotube growth using cobalt nanoparticles as catalyst. Appl Surf Sci. 2005; 249(1-4): 145-150.

[0186] 14. Lu M, Fatah N, Khodakov AY. Solvent-free synthesis of alumina supported cobalt catalysts for Fischer-Tropsch synthesis. J Energy Chem. 2016; 25(6): 1001-1007.

[0187] 15. Bahruji H, Esquius JR, Bowker M, Hutchings G, Armstrong RD, Jones W. Solvent Free Synthesis of PdZn / TiO2 Catalysts for the Hydrogenation of CO2 to Methanol. Top Catal. 2018; 61(3-4): 144-153.

[0188] 16. Ahmed W, El-Din MRN, Aboul-Enein AA, Awadallah AE. Effect of textural properties of alumina support on the catalytic performance of Ni / Al2O3 catalysts for hydrogen production via methane decomposition. J Nat Gas Sci Eng. 2015; 25: 359-366.

[0189] 17. Bayat N, Rezaei M, Meshkani F. Methane decomposition over Ni-Fe / Al2O3 catalysts for production of COx-free hydrogen and carbon nanofiber. Int J Hydrogen Energy. 2016; 41(3): 1574-1584.

[0190] 18. Zhao A, Ying W, Zhang H, Ma H, Fang D. Ni-Al2O3 catalysts prepared by solution combustion method for syngas methanation. Catal Commun. 2012; 17: 34-38. doi: 10.1016 / j.catcom.2011.10.010

Claims

1. A method for preparing a catalyst for a CARGEN process, wherein the catalyst is supported by a support material, the support material comprising Al2O3, the method comprising grinding a precursor material and a support material in a ball mill, wherein the precursor material comprises nickel oxide, wherein the ball mill comprises stainless steel balls of 5 mm diameter, wherein the ratio of the number of stainless steel balls in the ball mill to the weight of the catalyst in grams is from 1:1 to 100:1, wherein the catalyst is used in a CARGEN process to produce a high quality carbon material, and wherein the catalyst has an eggshell structure with weak support metal interaction.

2. The process according to claim 1, wherein the ratio of the number of stainless steel balls in the ball mill to the weight of the catalyst in grams is 10:1, and wherein the milling time is 1 hour. 3 . The method according to claim 1 , wherein the amount of the precursor material is 20 wt % of the total amount of the precursor material and the support material. The method of claim 1 , wherein the high-quality carbon material is MWCNT.

5. The method of claim 4, wherein the MWCNTs have a diameter of up to 100 nm.

6. The method according to claim 1, wherein the catalyst has a 2 / g total surface area.

7. The method of claim 1, wherein the catalyst has a 3 / g pore volume.

8. A catalyst for use in a CARGEN reactor prepared by the method according to claim 1.

9. A method of using the catalyst prepared by the method according to claim 1 in a CARGEN process.

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