Systems and methods for producing carbon solids

Abstract

Described are systems for producing graphitic carbon solids, comprising a plasma pyrolysis reactor, an inter-stage coupler, and a solids processing column. Also described is a method of producing graphitic carbon solids, comprising directing a hydrocarbon feedgas into the plasma pyrolysis reactor of the system.

Description

SYSTEMS AND METHODS FOR PRODUCING CARBON SOLIDSRELATED APPLICATIONS

[0001] This application claims the benefit of U. S. Provisional Application No.63 / 753,503, filed on February 4, 2025 and U. S. Provisional Application No. 63 / 821,644, filed on June 11, 2025. The entire teachings of the above applications are incorporated herein by reference.FIELD OF THE INVENTION

[0002] This application relates to systems and methods for the production of aromatic-based carbon solids and associated formulations comprising such carbon solids.BACKGROUND

[0003] Graphite is a high-value carbon solid whose multiple properties offer advantages for a wide number of industrial and commercial uses. As examples: its electrical conductivity makes it useful for manufacturing electronic components; its thermal conductivity makes it useful in heat exchangers and thermal management systems; its lubricity makes it useful as a friction-reducer and dry lubricant in multiple settings; its high melting point (around 6500°C) and low coefficient of thermal expansion makes it useful in high-temperature settings; its chemical inertness makes it useful in components encountering corrosive or reactive chemical environments.

[0004] As a prime example, graphite is crucially important in renewable storage applications, such as lithium-ion batteries that are used in electric vehicles (EVs) and other rechargeable electronic devices. Graphite is commonly employed as an anode material in lithium-ion batteries to store and release the lithium ions during charge and discharge cycles. Graphite’s unique structural properties, including its layered structure with relatively large interlayer spacing, afford multiple sites for lithium intercalation, while the weak binding between its layers results in a low intercalation voltage. Graphite thus permits reversible, high-capacity lithium intercalation and deintercalation during multiple charge / discharge cycles, making it an advantageous material for long-term cycling stability during battery use. As consumer demand for these products expands, so also does the need for high quality graphite to enable them.

[0005] Although graphite is widely used as an anode material in rechargeable batteries, its limitations for use in these products are well-known. During the lithiation and delithiation cycles of the graphite anode, it expands and contracts, producing mechanical stresses that can affect the structural stability of the material and ultimately impair its cycling stability. In addition, standard graphite's properties - while desirable - have room for improvement: for example, graphite has a limited specific capacity for lithium-ion storage, which can limit its use for long-range EV applications; and it permits relatively slow diffusion of lithium ions during charge and discharge cycles. While graphite’s planar geometry enables effective ion mobility, edges of each layer act as sites for electrolyte decomposition that negatively impacts the cell. There is considerable room for improving these properties of lithium-ion batteries, based on improving the properties of those materials used for battery anodes.

[0006] Graphite, due to its unique structural properties as well as its availability and cost-effectiveness, remains a mainstay of anode production. Historically, the material used for this purpose has been natural graphite, which is obtained (mined) from natural graphite deposits and is then processed into forms suitable for use in high-value applications such as rechargeable batteries. In more detail, the graphite ore is extracted from a suitable deposit, for example using open pit mining or underground mining techniques. The ore is then processed to extract the natural graphite and separate it from other impurities, with processing steps that include milling and crushing to reduce the size of the ore particles and beneficiation treatments to extract the graphite and improve its purity. The resulting purified graphite is then sized for its end use, and can be further shaped and sized as needed for a specific intended application. An important modification of size and shape is spheroidization, whereby the graphite particles are milled into a rounded, spheroid shape. This additional processing step, spheroidization, permits precise control of shape, size, and surface properties that are required by a specific, high-value application. However, while spheroidization is essential for making natural graphite suitable for important applications, this processing step has associated costs and complexities: it adds to the overall expense of graphite manufacture, both by requiring complex machinery and extra energy use: it is also resource-intensive, due to the loss of graphite feedstock as the mined particles are milled down: it imposes environmental burdens, which can affect the overall cost and can involve regulatory restrictions; and it necessitates rigorous quality control throughout the process to ensure that the end products conform to the stringent requirements imposed by their uses.

[0007] The limitations that graphite mining and processing entail are accompanied by geographic and geopolitical challenges. China is the largest current producer of natural graphite. This country currently produces the majority of the world’s natural and synthetic graphite, and over 90% of the world’s anodes for lithium-ion batteries. This concentration of graphite sources and production in China raises geopolitical concerns: whether the U. S. imposes tariffs on Chinese imports, or whether China restricts exports to the U. S., the supply of graphite from China to the U. S. can be adversely affected. Other producers of natural graphite are geographically remote from U. S. end-users, with mines in countries such as India, Brazil, Mozambique, and Madagascar. Currently, there is only one operating graphite mine in North America, the Northern Graphite mine in Québec. These geographic, environmental, and geopolitical challenges significantly affect the availability of natural graphite overall and the supply chain logistics, thus adversely affecting industrial end-users of these materials.

[0008] The impediments affecting the production and distribution of natural graphite have energized efforts to develop and commercialize synthetic graphite. As a consequence, graphite has earned a place in commercial applications in which precise control over properties and performance is required. Synthetic graphite, like natural graphite, is amenable to performance-improvement techniques such as coating and material modifications.Synthetic graphite is also particularly suitable for use in composites, such as those used as advanced anode materials.

[0009] While synthetic graphite offers the advantages of controllable properties and purity as needed in high-value applications, and further offers control over availability and geopolitical logistics, there are important limitations that restrict its use. A primary limitation is cost: synthetic graphite is typically more expensive to produce than its mined equivalent. The typical production process involves the controlled, high-temperature carbonization and graphitization of carbon-rich feedstocks such as petroleum coke or coal tar pitch, followed by purification, shaping, and sizing as required for the specific use. Requiring considerable energy input, its production is therefore expensive. Producing synthetic graphite also has a significant environmental impact beyond the energy consumption required due to the feedstocks it employs and the production of greenhouse gases that accompanies their processing. The production of synthetic graphite also involves multiple manufacturing steps such as carbonization, graphitization, purification, and sizing / shaping, which can involve specialized equipment and skilled personnel, which may be of limited availability.Sizing / shaping can be especially challenging technically, involving complex processingsteps with little margin for error. When synthetic graphite is finally produced in the desired size and shape, still its performance and properties may not be ideal for certain applications. All of these limitations for synthetic graphite need to be weighed against the properties, costs, and availability of natural graphite. Both natural and traditional synthetic graphite have strong disadvantages.

[0010] There remains a need in the art, therefore, for a synthetic graphite product that can capture the advantages of both synthetic and natural graphite while avoiding the current limitations that affect each substance. Advantageously, such a material can be customized to yield the advantages that are most important for a specific application. Advantageously, such a material can be manufactured at a commercial scale and at an economical price point. Further advantageously, such a material can be produced using technologies that impose less environmental burdens than those that are currently inflicted by natural or synthetic graphite production.SUMMARY

[0011] Disclosed herein, in embodiments, are systems for producing graphitic carbon solids, comprising a plasma pyrolysis reactor, an inter-stage coupler, and a solids processing column, wherein the plasma pyrolysis reactor comprises a microwave-energized subsystem for generating a plasma and an elongated cylinder within which the microwave-energized subsystem generates the plasma, wherein the elongated cylinder has a peripheral portion and a central portion radially, and a proximal portion and a distal portion axially, with a flow diverter positioned in the proximal portion, wherein a hydrocarbon feedgas enters the distal portion and flows in a vortical path from distal to proximal within the elongated cylinder as a first flow path, wherein the first flow path occupies the peripheral portion of the elongated cylinder; wherein the first flow path flows proximally until encountering the flow diverter at the proximal portion of the elongated cylinder, wherein the flow diverter diverts the first flow path to change directions and flow from proximal to distal, thereby forming a second flow path, and the flow diverter further directs the second flow path to flow within the central portion of the elongated cylinder; wherein microwave-energized subsystem forms a field of microwave energy within the central portion of the elongated cylinder and wherein the second flow path traverses the field of microwave energy, thereby forming a plasma from the hydrocarbon feedgas and transforming the hydrocarbon feedgas in the second flow path into an effluent stream comprising plasma-produced products, wherein the effluent stream flows distally within the elongated cylinder to exit the plasma pyrolysis reactor, andwherein the plasma-produced products comprise graphene nanoplatelets; wherein the inter-stage coupler is in fluid communication with the plasma pyrolysis reactor and receives the effluent stream that exits the plasma pyrolysis reactor, wherein the inter-stage coupler directs the effluent stream to enter the solids processing column and wherein the inter-stage coupler comprises a mechanism for temperature control of the graphene nanoplatelets; and wherein the solids processing column is in fluid communication with the inter-stage coupler and comprises an insulated processing tube that regulates the rate of cooling of the graphene nanoplatelets as they pass into and through the column, thereby producing a gradual and controlled decrease in particle temperature, wherein the decrease in particle temperature converts the graphene nanoplatelets into graphitic carbon solids.

[0012] In embodiments, the graphitic carbon solids comprise graphite or consist essentially of graphite. In embodiments, the graphene nanoplatelets comprise graphene clusters or consist essentially of graphene clusters. In embodiments, the graphene nanoplatelets act as seeds to nucleate the formation of the graphitic carbon solids. In embodiments, the mechanism for temperature control comprises a mechanism for rapid acceleration of the effluent stream, which mechanism can be a shaping structure, which shaping structure can comprise a nozzle. In embodiments, the mechanism for temperature control can comprise exposure to a cryogenic liquid, and the exposure can effect a rapid decrease in temperature, thereby preserving a disordered graphene morphology for the graphene nanoplatelets. In embodiments, the insulated processing tube provides a long, temperature-controlled path for the graphene nanoplatelets as they pass through the solids processing column, and the long, temperature-controlled path can be substantially similar in length to the solids processing column. In embodiments, the long, temperature-controlled path is curved or spiral in shape.

[0013] In embodiments, at least one of the inter-stage coupler and the solids processing column comprises an entry point for an additive to be admixed with the effluent stream. In embodiments, the inter-stage coupler provides the entry point, and the additive can comprise an oxidizing or a polar gas composition and / or a secondary’ feedstock, which can comprise a saturated hydrocarbon or an unsaturated hydrocarbon, and / or which can comprise a heteroatom. In the foregoing embodiments, the secondary feedstock in combination with the graphene nanoplatelets triggers the formation of the graphitic carbon solids. In embodiments, the solids processing column comprises the entry point, and the additive can comprise the secondary feedstock, which can comprise a saturated hydrocarbon or an unsaturated hydrocarbon, and / or which can comprise a heteroatom. In the foregoingembodiments, the secondary feedstock in combination with the graphene nanoplatelets triggers the formation of the graphitic carbon solids. In embodiments, the system further comprises a collector for recovering graphitic carbon solids, wherein the collector is positioned to recover the graphitic carbon solids from a system component selected from the group consisting of the plasma pyrolysis reactor, the inter-stage coupler, and the solids processing column.

[0014] Also disclosed herein, in embodiments are methods of producing graphitic carbon solids, comprising: providing the system as described above; directing a hydrocarbon feedgas to flow in a vortical flow along a first flow path from distal to proximal within the elongated cylinder of the plasma pyrolysis reactor and along the peripheral portion of the elongated cylinder until the hydrocarbon feedgas encounters the flow diverter, wherein the flow diverter reverses the first flow path and directs it distally and centrally to form a second flow path flowing from proximal to distal within the central portion of the elongated cylinder; energizing the hydrocarbon feedgas in the second flow path with the field of microwave energy provided by the microwave-energized subsystem to form a plasma, thereby converting the hydrocarbon feedgas into the effluent stream comprising graphene nanoplatelets that exits the plasma pyrolysis reactor; directing the effluent stream into the inter-stage coupler, wherein the inter-stage coupler regulates the temperature of the graphene nanoplatelets entrained in the effluent stream; and passing the effluent stream from the interstage coupler into the solids processing column and cooling the graphene nanoplatelets therein, wherein one or both substeps of regulating the temperature of the graphene nanoplatelets by the inter-stage coupler and / or cooling the graphene nanoplatelets by the solids processing column convert the graphene nanoplatelets into graphitic carbon solids. In embodiments, the graphene nanoplatelets comprise graphene clusters or consist essentially of graphene clusters.

[0015] In embodiments, the methods further comprise a step of admixing an additive to combine with the graphene nanoplatelets, wherein the step of admixing occurs in at least one of the plasma pyrolysis reactor, the inter-stage coupler, and the solids processing column. In embodiments, the step of admixing can take place in the inter-stage coupler or the solids processing column. In embodiments, the additive is an oxidizing or polar gas. In embodiments, the step of admixing produces an edge chemical modification of the solid graphene particles in the effluent. In embodiments, the step of admixing takes place by exposing the clustered graphene particles to a polar solvent, and the polar solvent can comprise an oxidizing agent or a strong acid. In embodiments, the step of admixing producessulfonated solid graphene particles. In embodiments, the additive can comprise a heteroatom, which can be silicon; such additives comprising silicon can comprise silane or tricholorosilane, and the step of admixing can produce silicon nanoparticles.

[0016] In embodiments, the methods further comprise a step of recovering the graphitic carbon solids from the system component selected from the group consisting of the plasma pyrolysis reactor, the inter-stage coupler, and the solids processing column. In embodiments, the step of recovering takes place following the step of admixing the additive to combine with the graphene nanoplatelets. In embodiments, the step of recovering takes place via a three-phase recovery process. In embodiments, the methods further comprise a step of mixing into a supportive matrix the graphitic carbon solids collected by the step of recovering the graphitic solids as described above, thereby creating a composite material comprising the graphitic carbon solids. The supportive matrix can be an inorganic matrix or an organic matrix, which can be an aliphatic matrix or an aromatic matrix. In embodiments, the step of mixing takes place by using a compatibilizer; in other embodiments, the step of mixing takes place by using a surfactant-loaded aqueous spray.

[0017] Further disclosed herein, in embodiments, are systems for producing graphitic carbon solids, comprising a plasma pyrolysis reactor, a solids processing column, and a solids separator, wherein the plasma pyrolysis reactor comprises a microwave-energized subsystem for generating a plasma and an elongated cylinder within which the microwave- energized subsystem generates the plasma, wherein the plasma yields chemical products and a hot effluent; wherein the solids processing column is in fluid communication with the plasma pyrolysis reactor, wherein the solids processing column and wherein the hot effluent passes from the pyrolysis reactor into the solids processing column; wherein the solids processing column comprises a growth feedgas inlet supplying a growth feedgas for treating the nanoscale carbon solids to change at least one of their size and shape, thereby converting the nanoscale carbon solids into processed graphitic carbon solids, and wherein the solids processing column passes the processed graphitic carbon solids from proximal to distal to pass into the solids separator; and wherein the solids separator is in fluid communication with the solids processing column and comprises one or more separation mechanisms that separate the processed graphitic carbon solids according to at least one of size and shape to yield a plurality of product particles. In embodiments, the processed graphitic carbon solids comprise graphite, or consist essentially of graphite. In embodiments, the nanoscale carbon solids comprise graphene clusters or consist essentially of graphene clusters. Inembodiments, the nanoscale carbon solids act as seeds to nucleate the formation of the processed graphitic carbon solids.BRIEF DESCRIPTION OF THE FIGURES

[0018] The foregoing and other objects, features and advantages of the invention will be apparent from the following more particular description of preferred embodiments of the invention, as illustrated in the accompanying drawings in which like reference characters refer to the same parts throughout the different views. The drawings are not necessarily to scale, emphasis instead being placed upon illustrating the principles of the invention.

[0019] FIG. 1 A provides a schematic diagram of an embodiment of a system for producing graphene and graphite.

[0020] FIG. IB provides a schematic diagram of an embodiment of a system for producing graphene and graphite.

[0021] FIG. 2 provides a schematic diagram of a flow path of the effluent from a plasma reactor for further reactions as used by an embodiment of the inventive systems and methods.

[0022] FIG. 3 provides a schematic diagram of a flow' path of the inflow stream into a plasma reactor as used by the inventive system and methods.

[0023] FIGs. 4A and 4B are TEM (transmission electron microscopy) images of graphene solids produced by the inventive systems and methods. FIG. 4B offers a magnified view of the graphene solids, as compared to the TEM image shown in FIG. 4A.DETAILED DESCRIPTION

[0024] The present invention relates to the unexpected discovery that synthetic graphite and associated materials such as turbostratic graphene and composites comprising this synthetic graphite and / or this turbostratic graphene can be produced in a controlled and customized manner using a process wherein plasma-produced turbostratic graphene clusters are directed into a solids processing column to act as seeds that enable the accumulation of multiple graphene layers to form spherical graphite particles. This process involves two separate sets of reactions: 1) the production of graphene clusters via plasma energization of hydrocarbon feedstock (Stage 1); and 2) the formation and growth of graphite particles using the graphene clusters from Stage 1 as nucleation seeds to support subsequent graphene layering to yield synthetic graphite (Stage 2). In embodiments, the graphene formed in Stage 1 can be harvested and commercialized separately. In other embodiments, the grapheneformed in Stage 1 can be used as nuclei in Stage 2 for the formation of the synthetic graphite particles. In yet other embodiments, Stage 2 provides a setting for other post-solid modifications.

[0025] In more detail, the systems and methods disclosed herein produce a spectrum of aromatic-based carbon solids. As used herein, the term “aromatic-based carbon solids” refers to a) graphene sheets, understood to be single layered carbon solids having sp2 hybridization and formed from aromatic carbon-carbon bonds; (b) graphene clusters, understood to be multidimensional carbon solids formed from disordered arrangements of graphene sheets; and (c) graphitic carbon solids, understood to be layered arrangements of graphene sheets or graphene clusters, whether arranged in planes or in curves (including open curves and closed curves), or some combination thereof. As used herein those aromatic-based carbon solids described in (a) or (b) above can also be termed individually or collectively “graphene nanoplatelets.” The process by which graphitic carbon solids are formed is termed “graphitization.” For avoidance of doubt, the graphene nanoplatelets have not yet undergone graphitization. As used herein, the term “graphitization” refers to the layering of graphene sheets or graphene clusters to formed layered arrangements thereof, whether arranged in planes or curves or some combination thereof; the term graphitization explicitly includes the process of forming spherical or ovoid layered arrangements, which can also be termed “onion-like.” The term “graphitic carbon solids” includes both ultrapure carbon black and graphite. Both forms of graphitic carbon solids are formed by graphitization and consist essentially of aromatic-carbon layers; it is understood that the carbon black particles formed by these systems and methods are substantially smaller in size than the graphite particles, with the former typically being less than 350 run in size, and with the latter being 350 nm in size. In the following disclosure, the formation of graphite is described in detail as an exemplary embodiment of those systems and methods disclosed herein for forming aromatic-based carbon solids.

[0026] In embodiments, the systems and methods disclosed herein provide a continuous and high-throughput process to create aromatic-based carbon solids (i.e., graphene nanoplatelets (graphene sheets and graphene clusters) and graphitic solids), and organic / inorganic composites and associated full formulations comprising such materials. As mentioned above, the systems and methods of Stage 1 can produce graphene nanoplatelets, which can be recovered separately and commercialized prior to entering into Stage 2 (for example, being recovered directly from Stage 1 or from an inter-stage coupler as described below), or which can be processed further in Stage 2, or both. Further, the systems andmethods of Stage 1, with their production of graphene nanoplatelets, can be integrated with the systems and methods of Stage 2 to produce graphitic solids such as graphite and carbon black, and related composites. In an exemplary embodiment, these systems and methods can be flexibly tuned to provide graphite and graphite-containing composites with specific, desirable properties. As an example, the combination of Stage 1 and Stage 2 processing can produce ultra-high-purity, spherical, controlled-particle-size, high-crystallinity, low-grain- boundary-density, synthetic graphite, with a layered, ordered geometry. In embodiments, the graphite particles are spheroidal in shape and layered, analogous to the layered arrangement found in spheroidal natural products like onions.

[0027] A schematic of an exemplary embodiment of the overall system disclosed herein is presented in FIG. 1A. FIG. 1A depicts schematically a system 100 for producing graphene, graphite, and optionally compositions comprising these carbon solids. The system 100 comprises a plasma pyrolysis reactor 102 (Stage 1), a solids processing column 120 (Stage 2), and an inter-stage coupler 110 connecting Stage 1 and Stage 2 and in fluid communication with both Stage 1 and Stage 2. As shown in the Figure, Stage 1 comprises a hydrocarbon feedgas 104 entering the plasma pyrolysis reactor 102, wherein a microwave plasma 108 formed by a microwave-energized subsystem (not shown) energizes and decomposes the hydrocarbon feed 104. Resulting from the pyrolysis process is a hot effluent 112 exiting the pyrolysis reactor 102 in which are entrained a plurality of graphene nanoplatelets 114. After the hot effluent 112 with its entrained graphene nanoplatelets 114 exits the plasma pyrolysis reactor 102, it is directed towards the solids processing column 120 via a shaped channel 118 such as a nozzle that directs the graphene nanoplatelets 114 into the solids processing column 120 at a desired flow rate and velocity, and that further controls the heat of the hot effluent 112 so that the graphene nanoplatelets 114 are at a desired temperature when they enter the thermally regulated processing column 120. The structures shown in FIG. 1 A directing the hot effluent 112 and its entrained graphene nanoplatelets 114 from the Stage 1 plasma pyrolysis reactor 102 into the solids processing column 120 can be termed, collectively, the inter-stage coupler 110. These structures comprising the inter-stage coupler comprise, without limitation, the shaped channel 118 such as a nozzle.

[0028] As the effluent stream from the inter-stage coupler 110 and the aromatic-based carbon solids entrained therein enter the solids processing column 120, the entering aromatic-based carbon solids 122 can undergo further processing as they progress through the solids processing column 120 along a processing flow path 130 represented as travellingfrom Point A (proximal) to Point B (distal). For avoidance of doubt, orienting terminologies such as "‘proximal” and “distal” and “top” and “bottom” are used with reference to the reactor design itself, and not with reference to anything external to the reactor: a proximal point (or a “top”) of a structure integrated in the system is closer to the plasma pyrolysis reactor 102 and a distal point (or a “bottom”) is further from the plasma pyrolysis reactor 102. In the depicted embodiment, the processing flow path 130 travels from Point A (proximal, located at the top end of the solids processing column 120 and closer to the plasma pyrolysis reactor 102) to Point B (distal, located at the bottom end of the solids processing column 120 and further from the plasma pyrolysis reactor 102) regardless of whether the reactor itself is oriented parallel to the Earth’s surface (or any other reference point) or perpendicular to the Earth's surface, or otherwise.

[0029] In an embodiment, the entering carbon solids particles 122 are predominantly graphene clusters, and the processes that take place in the solids processing column 120 results in the formation of a graphitic carbon solid, for example a multilayered graphite 128. This multilayered graphite 128 is deemed ultrapure because there is an absence of contaminants during its formation within the system 100. The processes for forming the multilayered graphite 128 are depicted schematically in the Figure. As shown in the Figure, the entering particles 122, predominantly graphene clusters, are processed in whole or in part by a change in temperature as the hot effluent 112 cools off in the processing column 120. In embodiments, the entering particles 122 cool, and thereby act as seed particles 124 to nucleate the formation of multilayered graphite 128. In other embodiments, with or without cooling, the entering particles 122 can act as seed particles by other mechanisms, for example by collision with other entering particles 122 or with other additive substances (not shown) that are introduced into the inter-stage coupler 110 or the processing column 120. Also, while not shown in this Figure, the seed particles 124 can nucleate the formation of the smaller graphitic carbon solid known as carbon black.

[0030] While the seed particles 124 are represented in this Figure as being distributed proximally in the processing column 120, with the multilayered graphite 128 being distributed distally in the processing column 120. it is understood that the seed particles 124 can provide nucleation for multilayered graphite 128 at any point along the processing column 120 if conditions are appropriate for their production. Depending on the needs for controlling parameters such as temperature, the column 120 can be made of a thermally insulating material, and does not have to be microwave-transparent. The column 120 canfurther be made of high-temperature-resistant ceramic or metal and can be insulated to maintain said high-temperature environment.

[0031] The Figure does not depict any mechanism for removal of the graphene or graphite particles from the system. However, a variety of capture and removal processes and subsystems can be used, depending on the particular type of aromatic-based carbon solid, composite, or formulation that is the designated product. Examples of such capture and removal processes and subsystems are described below for illustrative purposes. Other such processes and subsystems can be envisioned by practitioners in the arts of materials sciences and polymer sciences, and are embraced by the scope of the present invention.

[0032] In embodiments, the entering particles 122 transported through the inter-stage coupler 110 can have a similar morphology to the seed particles 124, for example a turbostratic graphene configuration comprising multidimensional carbon solids formed graphene sheets arranged three-dimensionally as a cluster or as a “blossom;” this arrangement can also be termed a graphene cluster. Without being bound by theory, it is envisioned that the graphene nanoplatelets 114 produced during the Stage 1 pyrolysis continue to grow and evolve morphologically as they pass from Stage 1 through the interstage coupler 110 and into the processing column 120, while also acting as seed particles around which further layers of graphene, hydrocarbons, or other materials can coalesce. In embodiments, such processes, as described below in more detail, can yield spherical graphite particles, in which the multilayered arrangement of carbon-containing layers assumes an onion-like configuration centered around one or more graphene-cluster seeds.Advantageously, the yield of spherical graphite particles is estimated to amplify the amount of graphene-cluster seed input by 103– 106. In other embodiments, such processes can yield spherical carbon black particles, which have a multilayered arrangement of graphene sheets or graphene clusters, and which also have a high degree of purity due to the absence of contaminants during their formation. Moreover, additional post-processing (not depicted in FIG. 1 A) can be employed to treat and / or remove undesirable compounds, such as PAHs or unintentionally synthesized polymers, from the aromatic-based carbon solids produced by the inventive methods.

[0033] In certain embodiments (not depicted in FIG. 1 A), the graphene-cluster seeds can undergo other treatments in the Stage 2 processing column that can produce modifications, composites, and other customized, functional formulations, some of which will be described below in connection with Stage 2.

[0034] Furthermore, while the exemplary system depicted in FIG. 1A comprises three components, a plasma pyrolysis reactor 102 (Stage 1), a solids processing column 120 (Stage 2), and an inter-stage coupler 110 connecting Stage 1 and Stage 2 and in fluid communication with both Stage 1 and Stage 2, in certain embodiments one or more of these components can be eliminated while still providing a continuous and high-throughput process to create aromatic-based carbon solids (i.e., graphene nanoplatelets (graphene sheets and graphene clusters) and graphitic solids), and organic / inorganic composites and associated full formulations comprising such materials. For example, in embodiments, the inter-stage coupler can be eliminated so that the plasma pyrolysis reactor (Stage 1) is in direct fluid communication with the solids processing column (Stage 2), and the desired products being recovered more or less directly from the solids processing column, as exemplified by the system depicted in FIG. 2. In other embodiments, the solids processing column (Stage 2) can be eliminated or circumvented, with the plasma pyrolysis reactor (Stage 1) in direct fluid communication with the inter-stage connector, but with the desired products (e.g.. graphene nanoplatelets) being recovered more or less directly from the interstage connector.

[0035] Therefore, while FIG. 1 A depicts an embodiment of a system 100 in which the inter-stage coupler 110 provides fluid communication between the Stage 1 reactor 102 and the solids processing column 120, in other embodiments not shown in this Figure, a system consistent with the principles of the invention can be constructed in which the inter-stage coupler functions in the absence of a solids processing coupler, with the inter-stage coupler providing an outlet for the effluent produced in Stage 1.

[0036] In more detail, in certain embodiments not shown in FIG. 1 A, a system consistent with the principles of the invention can be constructed in which the inter-stage coupler is absent, and in which Stage 1 is in direct fluid communication with Stage 2. An illustrative embodiment of this arrangement, in which an inter-stage coupler is absent, is depicted schematically in FIG. 2 below.

[0037] FIG. IB depicts another embodiment of an overall system 001 for plasma- powered and seeded synthetic graphite production, and for producing graphene and graphite. As depicted in this Figure, a plasma reactor 010 is provided, as described herein. Nucleation precursors 012, for example, nanomaterials produced in the plasma reactor, are processed in the plasma reactor as described herein, producing nanoscale carbon solids 014 that provide nucleation points for growth into graphitic particles. The effluent from the plasma reactor 010 containing the nanoscale carbon solids 014 passes through an orifice 018 into therefractory chamber 020. Passing into the refractory chamber 020, the nanoscale carbon solids 014 encounters a growth feed gas 022 that allows the formation of larger graphitic solids 024 as the particles ascend through the central portion of the refractory chamber 020. In embodiments, after their formation, the monodisperse nanoscale carbon solids 014 encounter high temperature hydrocarbons (predominantly acetylene) which thermally decompose to form layers of graphite around the monodisperse nanoscale carbon solids 014, forming the larger graphitic solids 024. The larger graphitic solids 024 rise within the refractory chamber 020 from its proximal end (i.e., the end nearer to the plasma reactor 010) towards its distal end (i.e., the end further from the plasma reactor 010), as indicated by segment “A"’ of the dashed path 026. The spent growth feed gas 022, comprising hydrogen gas or hydrocarbons or both, can be removed from the refractory chamber 020 via an exhaust circuit 034, which can provide a lower pressure outlet tract as compared to the pressure within the refractory chamber 020, thus enhancing the upward flow of the larger graphitic solids 024. However, as the larger graphitic solids 024 increase in size due to the accumulation of layers of graphite, they also increase in weight. Size of the particles will be controlled by the balance of particle weight vs gas drag, until ultimately the larger graphitic solids 024 are large enough to succumb to the forces of gravity' and reverse their direction, as shown by segment “B” of the dashed path 026. Those graphite particles large enough to reverse their direction fall from the distal part of the refractory chamber 020 towards the proximal end, while the lighter, smaller graphite particles continue growing by accumulating layers of graphite. These graphite particles are the graphite product particles 028, which are collected by a graphite collector 030 in the proximal part of the system 001. In the depicted embodiment, the dome at the top of the refractory chamber 020 and / or the sides of the refractory chamber 020 are constructed of material that is transparent to an impinging light or other form of irradiation, so that external heating 032 by irradiation can be provided. It is understood that heating mechanisms are optional, and while external heating 032 is desirable, other mechanisms for heating can be provided besides irradiation.

[0038] FIG. 2 shows a system 200 for plasma-powered and seeded synthetic graphite production, and for producing graphene and graphite, that can optionally be adapted for producing compositions comprising these carbon solids. The system 200 depicted in FIG. 2 comprises a plasma pyrolysis reactor 202 (Stage 1), a solids processing column 220 (Stage 2) and a solids separator 228, with the solids separator 228 in fluid communication with the solids processing column 220, which in turn is in fluid communication with the plasma pyrolysis reactor 202. In the plasma pyrolysis reactor 202, a feedgas 201 enters the reactor202 and is energized to form a plasma 204, for example a microwave plasma formed by a microwave-energized subsystem (not shown). The plasma 204 energizes and decomposes the feedgas, yielding products and a hot effluent 208. Residual plasma heat (>1500 °C) in the hot effluent 208 is carried into to the insulated propagation zone 222 of the solids processing column 220 where the reactive gases continue to grow the nanoscale carbon solids 212 into the processed graphitic carbon solids 216, as described in more detail below. In a preferred embodiment, the plasma 204 converts a carbon-containing precursor gas into carbon nanosolids and highly reactive gases (e.g., acetylene and ethylene) at precise rates.

[0039] As the hot effluent 208 approaches the distal end of the pyrolysis reactor 202 or passes into the proximal end of the solids processing column 220, it nucleates into nanosolids carried by a superheated unsaturated hydrocarbon gas such as hydrogen mixed with acetylene. The presence of superheated hydrocarbon gasses will enable continued growth of the nanosolids within the proximal section of the solids processing column 212. The dedicated inlet 210, shown here as entering the distal end of the pyrolysis reactor 202, can also be positioned in the proximal part of the solids processing column 220 where the nucleation feed gas still contacts the hot effluent 208 before it has substantially cooled. Whether positioned in the distal part of the pyrolysis reactor 202 or the proximal part of the solids processing column 220, the dedicated inlet 210 directs the nucleation feed gas into the hot effluent 208 such that nanoscale carbon solids 212 such as graphene nanoplatelets are formed. A channel (not shown) between the pyrolysis reactor 202 and the solids processing column 220 provides fluid communication between these two components of this system 200. This channel can be configured in a number of ways so that it directs the hot effluent 208 and the graphene solids 212 to enter the solids processing column 220 to undergo their propagation; advantageous shapes include, without limitation, a variety of nozzle shapes.

[0040] As the hot effluent 208 from the reactor 202, with the nanoscale carbon solids 212 entrained therein enter the solids processing column 220, the entering nanoscale carbon solids 212 can undergo further processing as they progress through the column 220 along a processing flow path 206, schematically represented as travelling from Point A (proximal) to Point B (distal) along the processing flow path 206. In an embodiment, the entering carbon solids particles 212 are predominantly graphene clusters, and the processes that take place in the solids processing column 220 results in the formation of a processed graphitic carbon solid 216, for example a multilayered graphite. In the depicted embodiment, the entering carbon solids particles 212, predominantly graphene clusters, are processed within the solids processing column 220 in whole or in part by a change in temperature as the hot effluent 208cools off within this structure. In embodiments, the entering carbon solids particles 212 cool and thereby act as seeds particles to nucleate the formation of multilayered graphite particles as the particles pass through the solids processing column 220.

[0041] As shown in this Figure, the solids processing column 220 can have two zones, a propagation zone 222 and an annealing zone 224. In the propagation zone 222, the entering carbon solids particles 212 encounter a growth feed gas 214 as they pass from proximal to distal in a direction along the processing flow path 206 from Point A to Point B. The growth feed gas can include, broadly, any hydrocarbon gas, for example an unsaturated hydrocarbon gas such as ethylene or acet lene. The decomposition of additional carbonaceous gases fed into the propagation zone into carbon solids will provide a heat of solid formation that continues the growth reactions. Passing along the processing flow path 206, the entering carbon solids particles 212 change their morphology and emerge from the propagation zone as processed graphitic carbon solids particles 216, for example changing from amorphous graphene clusters to graphitic solids such as multilayered graphite. Such processed graphitic carbon solids particles 216. such as multilayered graphite solids, are deemed ultrapure because there is an absence of contaminants during their formation within the system 200.

[0042] Within the solids processing column 220, the processed graphitic carbon solids 216 pass from the propagation zone 222 into the annealing zone 224, where they consolidate their shape. As an aid in this process, they can undergo treatment with a quench gas 218, which can enter the distal propagation zone 222 or the annealing zone 224. The quench gas 218, generally selected to stop grow th reactions, is intended to arrest the morphological evolution of the carbon solids particles 216 so that they achieve in near-final form a desired shape and size. Exemplary quenching agents include, without limitation, nonoxidizing agents such as water mist / steam and carbon dioxide at various temperatures, with specific quench gases and temperatures selected to optimize the degree and structure of the particulate carbon products while suppressing formation of undesired compounds such as polyaromatic hydrocarbons.

[0043] After passing through the annealing zone 224 of the solids processing column 220, the processed graphitic carbon solids 216 enter the solids separator 228, where they are separated according to size, shape, or other preselected criteria via one or more separation mechanisms. In the nonlimiting embodiment depicted schematically in the Figure, the processed graphitic carbon solids 216 can be stratified cyclonically 230 to recover product particles 232 of a designated size and shape, for example, larger graphite materials whichcan then be recovered from the overall system 200. In embodiments, other separation paths can be included, for example a filtration subsystem 234 combined with a pump mechanism 238 that can remove particles of other sizes and shapes from the stream that will yield the product particles 232, for example particles that are “stray particles” 238 that are too small or too irregular for productive use.A. Stage 1: Plasma-based Graphene Production1. Plasma Reactions Generally

[0044] Stage 1 comprises a plasma pyrolysis reactor excited by microwaves. In embodiments, the plasma used for these systems and methods is a microwave plasma, formed by a microwave-energized subsystem of the Stage 1 plasma pyrolysis reactor that directs microwave energy at the hydrocarbon-containing feedgas to form a plasma therefrom. The feedgas can be natural gas or biogas, LPG, or any mixed (waste) hydrocarbon gas. It can comprise alkanes such as, without limitation, methane, ethane, propane, butane, pentane, hexane, etc. and their cyclo-equivalents (and mixture thereof). It can comprise unsaturated compounds, such as ethylene, propylene, etc., or even trace amounts of acetylene (such as might be found in a product side stream from a conventional cracker).

[0045] The microwave plasma process described herein is a gas phase process, using gaseous reactant precursors to form desired gaseous products. Because of the very fast oscillation frequency of the electric field relative to the molecular and electronic collision frequencies, micro wave-gen erated plasmas are often in a high degree of non-equilibrium, meaning that electron and vibrational temperatures can be much greater than the gas temperature. In embodiments, collisions between the charged species (electrons, ions) and uncharged species (molecules, atoms, particles) within the microwave plasma transfer energy: this microwave-energized plasma supports a highly reactive chemical environment because of the energy contained in the plasma's free electrons. Because of the high degree of ionization of the precursor gas, the chemical dissociation and ionization of intermediates, and the elevated vibrational and excitational energies in the plasma, the desired chemical reactions described below proceed rapidly and efficiently.

[0046] Without being bound by theory, microwave radiation is understood to act as follows to create a plasma from a gaseous precursor. When the precursor gas (i.e., the hydrocarbon feedgas) is subjected to microwave radiation that meets or exceeds the dielectric strength of such gas, a free electron (present from background radiation or other sources) in the microwave field region is able to gain enough energy from the microwaveelectrical field in between collisions with neutral molecules that it can ionize another atom or molecule. The secondary ionized electron is subsequently accelerated in a direction that is governed by the electric field of microwave radiation, and it gains energy too until it causes another ionization event. This process of ionization progresses throughout the microwave field region until a steady state is reached. The final number of electrons in the plasma is determined mainly by the electron loss processes of the plasma, such as diffusion, recombination, and attachment. Through electron impacts, ionization, dissociation, and excitation, charged atomic and molecular species (e g., electrons, ions, radicals) are generated that can participate in chemical reactions.

[0047] As would be understood by skilled artisans, a multitude of reactions are available in a plasma, depending on the chemical nature of the feedgas. If a hydrocarbon feedgas is selected, the simplest reactions involve the simplest hydrocarbon, methane (CH4). The initial reaction of methane in the plasma results in the breaking of the C-H bonds, with resultant formation of CH3*, CH2*, CH*, H*, and C*. These radicals can recombine to form two-carbon fragments as exemplified by the following equations:CH3*+CH3*^C2H6CH2*+CH2*^C2H4CH*+CH*^C2H2CH3*+CH*^C2H4CH3*+CH2*^C2H4+H*CH3*+CH*^C2H4CH3*+CH*^C2H2+H2CH2*+CH*^C2H2+H*

[0048] In addition methane can combine with various radicals to form two-carbon fragments as exemplified by the following equations:CH4+CH3*^C2H6+H*CH4+CH2*→C2H5CH4+CH2*— > C2H4+2H* / H2CH4+CH*^C2H4+ H2CH4+CH*→C2H2+H*+H2

[0049] Besides the illustrated reactions to form two-carbon fragments and hydrogen, higher-order hydrocarbons can be formed by recombinations of plasma-generated radicals with each other and with the precursor gas. Furthermore, complete dehydrogenation of methane can take place, resulting in the formation of elemental carbon and hydrogen gas.

[0050] While not wishing to be bound by theory, it is proposed that the route to solids formation in the inventive plasma reactor follows a predictable mechanistic path. Here is an example, using ethane as an exemplary feedstock: plasma conversion of ethane to ethylene followed by ethylene to acetylene, whereupon the highly exothermic nature of acetylene decomposition to carbon solid is spontaneous (and explosively rapid). Solids formation as achieved by the systems and methods disclosed herein requires assembly of three acetylene molecules to form the first benzene ring and subsequent (rapid) lateral growth / attachment of numerous acetylene molecules fusing onto the growing graphene plane.2. Plasma Reactor Design

[0051] Achieving solids formation by these systems and methods has required overcoming the well-known tendency of solids formed in the plasma to accumulate on the wall of the plasma pyrolysis reactor and diminish the incident radiation within the reactor. In a microwave plasma system processing hydrocarbons to form acetylene and hydrogen, such as those disclosed in U. S. Pat. No. 11,634,324, (Soane et al.), solids formation is identified as a problem to be overcome. By contrast, the systems disclosed herein are constructed to facilitate the formation of solids via plasma-induced pyrolysis.

[0052] The plasma pyrolysis reactor employed for the present invention comprises an elongated cylinder within which the microwave-energized subsystem generates the plasma. The elongated cylinder has a peripheral portion and a central portion radially, and a proximal portion and a distal portion axially, with a flow diverter positioned in the proximal portion, as described below in more detail. The plasma pyrolysis reactor is specifically designed to avoid the formation of solids on the walls of the plasma pyrolysis reactor while permitting the formation of solids within the plasma itself via plasma-induced pyrolysis. In embodiments, the inflow stream or streams of the hydrocarbon feedgas can be directed to form selected geometric flow patterns. Vortical flow is an example of a geometrically arranged flow pattern that can include some or all of the feedgas in its streams.Advantageously, the flow pattern used to create the vortex is symmetrical. In embodiments, a single vortex can be formed, or multiple vortices can be formed. Varying the geometry’ of the vortex or vortices entering the reaction zone of the plasma reactor can allow optimization of product mixes and reaction efficiencies for forming the desired carbon solids product. In embodiments, the inflow stream or streams of the hydrocarbon feedgas can be directed into flow patterns having temporal variability, a feature that can be engineered to achieve desired reaction efficiencies. For example, the flow pattern of feedgas can involve a constant inflow of gas at a constant rate, or it can involve inflow of one or more feedgas streams at variableflow rates, in discontinuous flow patterns, or having other variations. As examples, feedgas streams can be introduced at different rates at from different inlets, or feedgas streams can be introduced with different flow patterns (such as varying continuous patterns, or patterns having intervals of discontinuity), with the flow patterns being the same at all inlets or differing at different inlets. One or more feedgas streams can also be introduced laterally along the reactor tube instead of or in addition to adding them at an end of the reactor tube. Appropriate geometric and temporal flow patterning and variations thereof can be determined by skilled artisans in order to accomplish specific goals, for example to increase the formulation of graphene-clusters or to suppress the formation of other, undesirable reaction products in the reactor.

[0053] For the systems and methods disclosed herein, the stability of fluid flow is of paramount importance to the product quality and system operability. Slight vortex imbalances and undulations during operation can result in a gradual build-up of carbonaceous deposits in the form of striations on the wall of the plasma reactor tube over long-duration operations. The use of a symmetrical vortex flow eliminates such undesirable phenomena. The use of a symmetrical vortex flow combined with a bidirectional injection path for the feedgas (as described below in more detail) combine to induce rapid solids formation: the system disclosed herein can be tuned to achieve production of solids predominantly or solely (optionally with the production and recovery of hydrogen gas) while the feedgas stream is traversing the intense plasma produced in the high-temperature core region of the reactor tube, while the stream is following its downward, centrally directed trajectory, the second limb of the bidirectional injection path. The solids thus produced are only produced in the core of the plasma pyrolysis reactor and not along the walls, and these solids are immediately pushed out of the Stage 1 plasma pyrolysis reactor, leaving no residue clinging to the tube wall. When pushed out of the plasma pyrolysis reactor rapidly, the particles can experience a drastic temperature drop - a steep gradient, i.e., rapid cooling. Under these circumstances, graphene platelets randomly stack - controlled by kinetics (platelet collision) not thermodynamics (repositioning and lattice fitting), yielding a collection of turbostratic graphene particulates under rapid cooling conditions. The product formed is a disordered aggregate of graphene sheets, arrayed as a cluster or a blossom, that has been formed by the rapid cooling conditions.

[0054] A diagram showing the flow path of the inflow stream into and out of the plasma reactor is shown in FIG. 3. FIG. 3 presents a longitudinal cross-section of a plasma pyrolysis system 300 with a bidirectional injection path shown within the plasma pyrolysisreactor 302. As shown in the Figure, an inflow 304 of the hydrocarbon feedgas enters the plasma pyrolysis reactor 302 through one or more inflow nozzles 306 located at the distal end of the plasma pyrolysis reactor 302, and is conveyed retrograde (i.e., from distal to proximal) from the bottom end 308 of the reactor 302 towards the top end 310 of the reactor 302 via a path that proceeds along the periphery 312 of the reactor 302. As depicted in this Figure, the inflow 304 is subjected to a vortical flow 324 as it proceeds towards the top end 310; the inflowing feedgas ascends through the plasma pyrolysis reactor 302 along the outer wall 316 while vortexing radially. As it ascends, the inflow' gas 304 is at a relatively modest temperature, as it does not experience plasma breakdown while ascending along the outer wall 316, due to the maximum electric field oscillations from the microwave subsystem being tuned to be localized in the central portion 320 of the cylindrical reactor 302. At the top end 310 of the plasma pyrolysis reactor 302, the inflow' 304 encounters a flow diverter 314 w'hich redirects and reverses its flow', directing the reversed flow away from the periphery 312 towards the central portion 320 and maintaining the vortical flow configuration.

[0055] The flow diverter 314 is shown here as a discontinuous plate protruding from the wall 316 of the reactor 302; such a platelike structure can have a larger or smaller area of discontinuity. In other embodiments, the flow' diverter 314 can be shaped as a flattened toroidal structure disposed circumferentially at the top end 310 of the reactor 302. Other shapes and structures can also be envisioned for the flow diverter 314. such as, for example, a dome shape that is widest at its downward-facing aspect, or an inverted dome shape that is narrowest at its downward-facing aspect, or a planar structure disposed at a right angle or any other angle to the length of the reactor 302. Without limitation, shapes or structures functioning as flow diverters 314 can be positioned at the top end 310 of the reactor 302 in any position that allow them to redirect the upward (distal to proximal) flow of the inflow 304 so that it reverses direction and proceeds towards from proximal to distal towards the bottom end 308 of the plasma pyrolysis reactor 302, desirably while maintaining the vortical flow pattern 324. After its encounter with the flow diverter, the inflow 304 has been redirected axially to pass from proximal to distal, and the redirected flow 318 has further been redirected radially to become located in the central portion 320 of the cylindrical plasma pyrolysis reactor 302, flow'ing therein tow'ards the bottom end 308 of the reactor 302 to be processed by the plasma (not shown) within the central portion 320 of the reactor 302. After passing through the central portion 320 of the plasma pyrolysis reactor 302, the redirected flow 318 exits the reactor 302 distally, at its bottom end 308. At that point, thehydrocarbon feedgas in the redirected flow 318 has been pyrolyzed within the plasma, yielding the aromatic-based carbon solids reaction products such as graphene clusters that are entrained in the effluent 328 that exits the bottom end 308 of the reactor 302. After exiting the bottom end, the effluent 328 passes through a structure such as a nozzle (not shown) that shapes the flow of the effluent 328 and can direct the effluent 328 to enter the inter-stage coupler that connects the Stage 1 plasma pyrolysis system 300 to the Stage 2 processing column, as depicted in more detail in FIG. 1A. In other embodiments, the effluent 328 can enter the inter-stage coupler and undergo flow shaping therein, for example by being passed through a constriction within the inter-stage coupler (not shown), or by being passed through a nozzle (not shown) situated at the distal end of the inter-stage coupler, for example that passes the effluent from the inter-stage coupler into the Stage 2 processing column. In yet other embodiments, the effluent 328 can pass directly into Stage 2, as is depicted and described in more detail in conjunction with FIG. 2.

[0056] Using such a system, the hydrocarbon feedgas can be efficiently transformed into aromatic-based carbon solids while preventing them from adhering to the walls of the plasma pyrolysis reactor after they are formed. Since the feedgas flowing along the walls of the plasma pyrolysis reactor is relatively cool, little or no chemical conversion takes place within this portion of the gas stream. Instead, the cool gas prevents solids formation, and the gas flow along the reactor walls can dislodge any deposits that form there, so that virtually no carbon solids are deposited on the inner reactor walls.

[0057] When the flow reverses and the gas descends within the reactor’s inner (central) core portion (while continuing the vortexing), an intense plasma zone is struck by its interaction with the microwave energy produced by the microwave-energized subsystem. The bidirectional flow pattern for the feed gases ensures that virtually all feedgas molecules pass through the plasma zone for reaction, undergoing quantitative conversion and high selectivity. The aforementioned mechanistic path (feedgas to ethane, ethane to ethylene, ethylene to acetylene, ethylene / acetylene to solids) comes into play with explosive speed. Since all gas molecules must traverse this highly confined region, no / little bypass (thus no / little PAH (polyaromatic hydrocarbons) formation) takes place. Moreover, the intense heat in the central portion of the plasma tube causes rapid reaction, with complete pyrolysis of the feedgas at this site within the reactor to yield elemental carbon. The resulting solids are of extremely high quality.

[0058] Graphene clusters formed in accordance with the systems and methods of Stage 1 exhibit disordered stacking, also known as turbostratic stacking, in which adhesionbetween edges and planes is weak. Examples of the Stage 1 graphene clusters are shown in the TEM (transmission electron microscopy) images of FIGS. 4A and 4B. This morphology renders the graphene clusters produced in Stage 1 suitable for uses which they are themselves dispersed in a medium (either as-is, or as modified) such as a composite matrix or a liquid continuous phase exemplified by an emulsion. In addition, the graphene clusters thus formed can act as nuclei for further elemental carbon deposition in the Stage 2 solids processing column, resulting in the formation of graphitic carbon solids such as carbon black particles and / or spherical synthetic graphite with highly ordered interlayer stacking and extremely high purity. Exemplary processes for forming the synthetic graphite is discussed below in more detail.

[0059] In embodiments, the plasma system itself can be modified or manipulated in order to select for a particular graphitic carbon solids morphology. The system as described so far has been tuned to produce graphene solids such as graphene platelets arranged with a disordered, clustered structure. However, the plasma power can be reduced vs. the power needed to optimize graphene production, and / or the residence time of the particles in the plasma zone can be increased by decreasing the feed flow rate, predisposing the emerging graphene clusters to grow into highly spherical synthetic graphite with ordered interlayer stacking.

[0060] In embodiments, the feedgas composition can be modified or manipulated in order to select for a particular solids morphology. Adding other feed gases to the primary hydrocarbon feedstock can affect the types of solids that are formed. For example, addition of hydrogen to the hydrocarbon feedgas increases the tendency to produce graphite instead of graphene. Adjusting the composition of a feedgas mixture temporally can also affect the rate of particle growth and the resulting average diameter of the graphitic carbon solids such as the spherical graphite produced by the system. In embodiments, it is possible to dynamically tune the particle size distribution by pulsing in or shutting off a certain feedgas component. Advantageously, one can auto-program any time-dependent feed composition, thus fashioning end-product attributes accordingly without having to mix product solids from different runs post-production. The ability to auto-tune particle attributes on the fly can decrease or eliminate the need for a troublesome step post-production, facilitating mixed size distributions of the particles for specific purposes. Advantageously, the bimodal size distribution of the graphitic carbon solids (e.g., synthetic graphite) thus manufactured can permit, for example, very efficient compaction of graphite as it is used to make high- performance anodes.

[0061] While the systems and methods of the present invention produce graphene clusters that are used to nucleate synthetic graphene, these systems and methods also permit the graphene clusters to be recovered independently. In embodiments, the graphene clusters can be recovered directly from Stage 1, while in other embodiments, they can also be recovered from the inter-stage coupler or from Stage 2 without undergoing further graphitization, for example by rapidly cooling the effluent stream in which the particles are entrained. In embodiments, this rapid cooling can be accomplished by the injection of a cryogenically chilled super-cooled inert gas or liquid into the proximal portion of the particular section, which will rapidly quench the evolving conversion of the graphene clusters from turbostratic stacking to Bemal (ordered) stacking. In certain embodiments, the graphene clusters can be rapidly dispersed into other media or matrices without graphitization to create graphene-bearing composites.

[0062] In preferred embodiments, however, the graphene clusters produced in Stage 1 are used as “seeds” to nucleate the formation of graphitic carbon solids such as synthetic graphite in Stage 2, which can then be recovered as a product that is distinct from the graphene clusters that had been formed in Stage 1. In certain embodiments, the graphene seeds can be used to nucleate the formation of specialized, customized forms of graphite and / or graphite composites in Stage 2 by exposing the graphene-cluster seeds to secondary feedstocks that interact with the graphene-cluster seeds, modifying the graphene seeds or the graphitic carbon solids that they generate.B. Carbon Solids Processing1. Stage 1, Stage 2 and the Inter-stage Coupler

[0063] Stage 2 of the systems and methods disclosed herein permits the growth of multilayered materials that begins with the graphene clusters produced in Stage 1. Before entering Stage 2, the graphene clusters produced in Stage 1 can be subjected to an engineered temperature gradient as the gas / particle mixture follows the flow trajectory from the plasma zone towards the processing column of Stage 2 via the inter-stage coupler, which connects Stage 1 to Stage 2. The velocity and shape of the fluid stream can be shaped within the inter-stage coupler as desired via appropriate shaping processes or shaping structures, such as a jet nozzle or a converging / diverging nozzle. The specific geometry of a nozzle used for these purposes can be engineered so as to control the exact power / pressure / flowrate of the fluid stream as it enters the processing column.

[0064] In preferred embodiments, the fluid stream passing from Stage 1 into Stage 2 is engineered specifically to convert the graphene nanoplatelets from Stage 1 into syntheticgraphite. In other embodiments, the fluid stream can be controlled in order to maximize random stacking of single-layered aromatic-based carbon solids, for example by drastically decreasing its temperature: this can be accomplished by exposing the effluent to a cryogenic fluid, as described above, or it can be accomplished by rapidly accelerating the effluent as it is expelled from the plasma zone and as it passes into the inter-stage coupler. Such rapid acceleration (for example via an appropriately designed shaping structure such as a nozzle) can result in a drastic decrease in temperature that leads the aromatic-based carbon solids formed in Stage 1 to agglomerate / stack incoherently like random flat flakes, leaving large voids in between them as they form a weakly consolidated mass. In short, the key to morphology control is post-formation temperature gradient control. A rapid decrease in temperature predisposes to the formation of turbostratic graphene clusters. By contrast, slowing the transit from the Stage 1 reactor into or through Stage 2 (thus lowering the temperature gradient as the fluid follows the trajectory of particle flow) allows much improved and orderly stacking around the entering carbon nanoplatelets, in particular graphene clusters, giving rise to graphitic carbon solids with increasing size and in desirable shapes such as spheroid structures. Product morphology can be precisely controlled and highly tunable, ranging from isolated turbostratic graphene clusters to high-value, multilaminar graphitic carbon solids such as ultrapure carbon black and ultrapure synthetic graphite.

[0065] In embodiments, the inter-stage coupler is intended to guide the particle mixture smoothly from Stage 1 to Stage 2, with potential for preserving a vortical flow pattern in the effluent. The diameter of the Stage 1 reactor outlet and the Stage 2 processing column may be the same or quite different, with the inter-stage coupler providing controlled transition between the two. Further, inter-stage design and operating conditions affect the temperature gradient experienced by the particles, as described above. In addition, the direction of injection can be co-rotating or counter-rotating with the prevailing vortex, or simply straight-on: all lead to different flow' patterns which can be accurately predicted and chosen on a case-by-case basis, depending on the desired aromatic-based carbon solids products (e.g., clustered graphene or graphitic carbon solids such as graphite).

[0066] Furthermore, the inter-stage coupler can provide an entry point for additives that are to be admixed with the effluent stream, affecting the aromatic-based carbon solids entrained therein. For example, chemicals can be introduced into the stream via multiple orifices or slits (rounded or otherwise) in the inter-stage coupler to affect the aromatic-based carbon solids therein, pointing upward, straight-on, or downward at or near its junctions withStage 2 or Stage 1 as appropriate. The openings of the orifices or slits can be positioned slightly up or down from the narrow throat of a nozzle, or at the throat itself. For edge chemical modification, a very small amount of the reactive chemical(s) is needed (compared to the effluent flow from Stage 1) so the injection ports are selected based on the residence time required to achieve chemical modification. On the other hand, to capture the aromatic- based carbon solids (e.g., graphene nanoplatelets and / or graphitic carbon solids) in the ultimate composite matrices (or matrix-precursors) a much larger amount of the receiver liquids is needed, making the injection site for these additives preferably positioned in Stage 2 itself.

[0067] As described previously, controlling temperature in the outflow from Stage 1 is a key to producing a graphitic carbon solid such as graphite from the graphene nanoplatelets produced in Stage 1, such as the graphene clusters. The inter-stage coupler offers mechanisms for such temperature control, for example nozzle design. Depending on the rate of temperature decrease, the system will be predisposed to retain disordered graphene clusters in the product mix (if temperature decrease is rapid), or will permit the more gradual formation of multilaminar graphite (if temperature decrease is slow). To effect optimal spherical graphite formation, a long, temperature-controlled path can be provided for the carbon particles exiting Stage 1 to allow ample time for graphitization, particle / crystal growth and spheroidization. This temperature-controlled path can involve both the interstage coupler and Stage 2. In embodiments, the temperature-controlled path can follow a curved, recurved, or spiral path, or other path selected to optimize temperature control.

[0068] In addition to those mechanisms instituted in the inter-stage coupler, Stage 2 adds more elements of control over the temperature gradient. For example, to facilitate the formation of graphite, the inter-stage coupler directs the graphene nanoplatelets, such as the graphene clusters, into the long, insulated processing section of Stage 2 to limit the rate of cooling for the particles so that they slowly anneal, consolidate, and grow in size to become high-value synthetic graphite. The Stage 2 column can contain a method of recirculating its contents to prevent sedimentation and maintain an active heated region. Methods of recirculation can include the addition of precursor or inert gases through a jet or nozzle, a fan system, directing the Stage 1 and 2 inflows with the reactor walls, and / or similar methods. As an adjunct for temperature control, optionally a heated inert gas can be introduced or an extra amount of insulating material can be provided to further keep the particles hot to allow graphitic planes to continue to deposit in an orderly manner on growing particles as the graphitic carbon solids are produced. In contrast, as described above, a rapid decrease inparticle temperature can be achieved, for example, by injecting a cryogenically chilled inert gas or liquid into the hot effluent or otherwise accentuating the temperature gradient, which will result in a preservation of disordered graphene morphology. However for graphite production, a gradual, controlled decrease in particle temperature is desirable, which can allow multiple layers of carbon to congeal around one or more core graphene seeds as the particles grow in size; similarly, for production of carbon black, a gradual, controlled decrease in particle temperature is desirable, with mechanisms employed to restrict the growth of the growing particles or to remove them while they are smaller in size, consistent w ith the structure and definition of carbon black. Maintaining a very high temperature region for the primary reactions in Stage 1 and the subsequent graphitization to take place can minimize formation of PAHs and unwanted compounds, enabling high purity graphitic carbon solids to be formed. The shape and size of the Stage 2 processing column is designed with reference to the other components of the overall system, such as the Stage 1 reactor outlet and the inter-stage coupler, and with reference to the products to be generated.2. Modifying carbon solids

[0069] While the foregoing systems and methods for producing aromatic-based carbon solids have been described with particular reference to producing graphene clusters and graphitic carbon solids such as artificial graphite therefrom, further material refinement of these products is consistent with the principles of the invention. In embodiments, numerous modifications of the aromatic-based carbon solids such as graphene clusters and artificial graphite are possible. Exemplary, non-limiting, descriptions of such modifications are provided below.a. Edge chemical modification

[0070] As the graphene nanoplatelets in the Stage 1 effluent pass into and through the inter-stage coupler, they can be immediately contacted with an oxidizing or polar gas composition (such as lean oxygen, water vapor, H2S, CO2, CO, NOx, SOx, ammonia, or mixture thereof) to cause substitution of edge hydrogen by the corresponding alcohol, amine, carboxylic groups, yielding modified graphene nanoplatelets. This edge chemical modification can facilitate subsequent functionalization or dispersion of the modified graphene nanoplatelets in polar solvents or matrices. As another edge chemical modification, the familiar tetraethyl orthosilicate (TEOS) chemistry can be implemented to create modified graphene nanoplatelets with edge-coupled silica nano-attachments. This product conjugate greatly facilitates mixing and dispersion of the graphene nanoplatelets produced in Stage 1 into inorganic matrices such as plaster and / or cement. As another edge chemicalmodification, dimethyldichlorosilane, which upon polymerization yields polydimethylsiloxane (PDMS) can be used to attach silicone chains to graphene, thereby enhancing dispersion of the graphene nanoplatelets produced in Stage 1 into thermoplastic silicone liquids and / or curable silicone resins. End-cap frequency of the silicone polymers can be regulated by adding a substance such as trimethylmonochlorosilane to control PDMS chain length. Alternatively, edge chemical modification to affect graphene nanoplatelets or graphitic carbon solids can be performed at the level of the inter-stage coupler and / or the solids processing column.

[0071] In addition to edge chemical modification, the graphene nanoplatelets produced in Stage 1 may be adsorbed onto or into droplets of polar solvents (e.g., NMP. water, among many others). To enable edge chemistry modification in a liquid dispersed state, the solvent can contain an oxidizing agent or strong acid (such as perchlorate, permanganate, sulfuric acid, or nitric acid or combinations thereof). For example, sulfonated graphene has enhanced dispersibility in polar matrices.b. Secondary feedstocks

[0072] Graphene nanoplatelets formed in Stage 1 can be used as seeds that trigger additional deposition of heat-induced and just-formed graphitic layers on the growing particles, as described above. In addition, other, secondary, feedstocks can be added to the graphene-containing effluent stream produced in Stage 1 as it passes through the inter-stage coupler into and through Stage 2. Depending on the length of the inter-stage coupler and the processing column, and depending on the temperature profile as the growing particles move from Stage 1 through the inter-stage coupler to and through Stage 2, adding various secondary feedstocks allows flexible tuning and precise control of particle size for subsequent formation of graphitic carbon solids such as synthetic graphite. Furthermore, by adding unsaturated species to the graphene-cluster seeds and the graphitic carbon solids (such as multilayered graphite) formed therefrom, an exothermic conversion of the secondary feedgas into various forms of graphitic hydrocarbon takes place. Without being bound by theory, it is understood that this exothermic conversion means that a trigger event combining the Stage I effluent with an appropriate secondary feedstock can theoretically cause limitless consumption / con version of the secondary feed stream into layered graphitic structures. Thus, the two-stage process as disclosed herein, including the addition of an appropriate secondary feedstock, provides an extremely energy efficient way to manufacture graphitic carbon solids such as synthetic graphite, along with modified forms thereof. As described in conjunction with FIG. 1A, in embodiments, an inter-stage coupler can beemployed to afford certain elements of control over the process for forming the graphitic carbon solids. In other embodiments, as mentioned previously, the inter-stage coupler can be omitted, with the Stage 1 effluent proceeding directly into Stage 2. An exemplary embodiment for this flow path is depicted schematically in FIG. 2.

[0073] As secondary feedstock can be injected at any level axially along the effluent path after it leaves the plasma reactor, whether at the level of the inter-stage coupler or at the Stage 2 level, or both. This secondary feedstock can comprise saturated hydrocarbons (e.g., methane, ethane, propane, etc.), unsaturated hydrocarbons (e.g., ethylene or acetylene) or mixtures thereof. As described above, upon exposure to the secondary feedstock the graphene nanoplatelets from Stage One can serve as ‘‘seeds” triggering additional deposition of heat-induced and just-formed graphitic layers derived from the secondary feedstock onto the growing graphitic carbon solids, optionally permitting modifications thereof.

[0074] Multiple injection sites for the injection of one or more secondary feedstocks can be situated along the effluent path as it progresses from the outflow tract of the plasma pyrolysis reactor through the inter-stage coupler, into and through the processing column. For example, a secondary feedstock can be injected into the inter-stage coupler, and / or into the processing column at one site or at a plurality of sites along the longitudinal axis of the system, for example, immediately below the coupler region and subsequently and optionally at different locations downstream. The composition of the injected hydrocarbon streams may differ for different injection sites, to effectuate growth rate control. In general, exposing the seeds to a single secondary feedstock produces largely spherical synthetic graphite with monodisperse diameters; adding one or more additional secondary feedstocks can create one or more separate populations of synthetic graphite particles with different diameters, allowing recovery of synthetic graphite having an engineered multimodal size distribution.

[0075] Feedstocks comprising heteroatoms can also be employed as secondary feedstocks in the inventive systems and methods, either alone or in combination with hydrocarbon feedstocks. For example, sulfur- or nitrogen-containing volatiles (e.g., H2S or ammonia) can be co-introduced with hydrocarbon, leading to sulfur or nitrogen linked to the graphitic edge chemistry on the outermost layer(s) of the aromatic-based carbon solids products.c. SiNP inclusion

[0076] Formation of graphene clusters in Stage 1 and their subsequent passage into the processing column of Stage 2, whether through the inter-stage coupler or directly, provides an advantageous setting for the creation of SiNP (silicon nanoparticles) and theirimmediate trapping in a graphitic matrix. In accordance with these systems and methods, silicon nanomaterials can be injected from the boundaries of the inter-stage coupler to enable their integration into graphene clusters and graphitic solids resulting therefrom, resulting in a carbon-silicon composite. The relative ratio of the graphene clusters and / or graphitic solids and the silicon nanoparticles can be easily tuned by the relative flowrates of the hydrocarbon feed in Stage 1 and the vaporous silane reactant(s) injected thereafter. Note that the size of the SiNP is limited by the very narrow reaction window (the impingement zone) and extremely short transit time of the reactive gases. Particle generation occurs on the surface of the aromatic-based solids, ensuring intimate adhesion of SiNP and carbon (a very desirable outcome).3. Solids Capture in Compatibilizers and / or Supporting Matrices

[0077] As described herein, the inventive systems and methods can produce aromatic- based carbon solids in various forms at the different levels of the systems, i.e., Stage 1, interstage coupler (if present), and Stage 2. A variety of collection (i.e., recovery) methods are available for integration with these systems, in particular at the inter-stage coupler level and at the Stage 2 level. Collection methods and equipment can be customized in light of the physical and chemical features of the solids that have been produced.

[0078] In an exemplary embodiment, traditional pulse jet filtration techniques (and associated equipment / disposables) such as are employed by the carbon black industry can be used in conjunction with the inventive systems and methods to ensnare and retrieve (i.e., recover) the produced solids. Instead, or in addition, multiple additional technologies can be implemented either directly beneath Stage 2 or as a part of Stage 2 to facilitate recovery. In embodiments, to optimize the use of these techniques, auxiliary compatibilization techniques can also be employed.

[0079] Compatibilization techniques, familiar in the polymer arts, involve adding a substance to a blend of two or more different, otherwise poorly miscible, polymers to enhance their blending, yielding a polymeric mixture with improved properties, and / or with properties that may not be attainable in a formulation comprising only a single polymer. In embodiments, principles of compatibilization can be employed to enhance recovery of the solids produced by the systems and methods disclosed herein.

[0080] Composite materials can be produced by embedding or otherwise integrating particulate matter such as the graphene nanoplatelets and graphitic carbon solids in supporting matrices. As used herein, the term “supporting matrix” is to be construed broadly as encompassing both inorganic and organic fluids or solids that provide a continuous phasewithin which the aromatic-based carbon solids disclosed herein are supported without undergoing substantial chemical change. As will be described below in more detail, auxiliary processing can be employed to facilitate the integration of the aromatic-based carbon solids disclosed herein into supporting matrices.

[0081] As has been previously described, the solids produced by the systems and methods disclosed herein (i.e., graphene nanoplatelets and graphitic carbon solids) are fundamentally aromatic, having fused phenyl rings; thus they do not mix well naturally with aliphatic matrices such as PE, PP, or EPDM. However, such mixing would be advantageous for many commercial applications. For example, EPDM (ethylene propylene diene monomer) rubber is a type of synthetic rubber that is used in many roofing or water-proofing applications; it is manufactured from dienes such as ethylidene norbornene, dicyclopentadiene. and vinyl norbornene. Such a material, though, does not mix well naturally with fundamentally aromatic materials. Similarly, polar polymers such as PVC and acrylics do not mix well with aromatic inclusions. Without modification or compatibilization. aromatic-based carbon solids such as are produced by the systems and methods disclosed herein will integrate poorly into such matrices. Instead, to facilitate this integration, modification and / or compatibilization of these aromatic-based carbon solids can be performed.

[0082] In contrast with the foregoing aliphatic matrices, styrenics (polystyrene and polystyrene copolymers, both random and block) allow much better dispersion of aromatic- based carbon solids such as those produced by the systems and methods disclosed herein. Aromatic epoxies and urethanes similarly host aromatic-based carbon solids dispersions better than their aliphatic variants. Also, heavy fractions of a barrel of crude, such as bitumen or tar, allow ready dispersion of graphene (provided it is produced m the turbostratic state).

[0083] Compatibilizers can be used to facilitate the integration of aromatic -based carbon solids into non-aromatic matrices. For example, alkylbenzenes (both long chain linear and branched alkyls) lower the surface tension between the nano-platelets and non- aromatic matrices. Plasticizers such as the Benzoflex™ series and various phenol -ether surfactants (some are slowly evaporating volatile solvents) serve the same function for PVC and polyurethanes, and greatly promote dispersion of graphitic solids in subsequent mixing (master batching) operations.

[0084] Compatibilizers can be introduced into the systems disclosed herein by any conventional mechanism. For example, multiple injectors can be provided at the inter-stagecoupler level or in Stage 2 to spray such compatibilizer liquids onto the emerging solid particulates at these levels. Advantageously, the injectors can be located in Stage 2, as the available temperature gradients and modifications thereof can provide more favorable temperatures for compatibilizer interaction In embodiments, once the aromatic-based carbon solids particles produced in these systems and the liquid droplets of the compatibilizer liquids adhere to each other, the resulting mixture can be readily collected. This interaction and collection can be achieved through a spray of droplets, and / or a coating of surfaces in a flow of compatibilizer, or other similar techniques as would be familiar to skilled artisans. Note that these compatibilized liquid formulations can be blended to include other ingredients such as monomers, crosslinkers, polymer precursors (in oligomeric form), and initiators / catalysts, etc., so that a functional formulation is produced that is a solid-loaded liquid available for transformation into a final composite form, by simultaneous or consecutive polymerization / shaping, via any of the polymer processing unit operations familiar in the art, such as fiber spinning, extrusion, calendaring, spin-coating, injection, reactive injection, and / or compression molding. For example, to produce a formulation destined to become a thermoset, the aromatic solids component may be introduced into one of the two reactants (e.g., aromatic isocyanate or epoxy). Upon mixing with the polyol (or hardener) in a reaction injection molding (RIM) or casting operation, the solid-loaded thermoset is formed in the final shape (foam or otherwise).

[0085] In other embodiments, where rapid and effective dispersion of aromatic solids in inorganic systems or aqueous media (such as emulsions) is desired, the carbon particles can be captured by a spray of surfactant-loaded water or other aqueous solvent. Notable surfactants to promote subsequent dispersion themselves contain aromatic hydrophobic groups. In addition to phenyl-based surfactants, naphthalene- and anthracene-based surfactants are particularly effective to form a thin (monolayer) coating on graphitic planes, serving to bridge the interface between the dispersed solids and water; similar polar solvents, such as alcohols and glycols, NMP, formamide, DMSO, or mixtures thereof, can also be employed. Inorganic products, such as plaster board and cement / concrete, greatly benefit from inclusion of aromatic-based carbon solids produced by these systems and methods such as graphene clusters: pretreated / pre-compatibilized. intimate and uniform dispersions of formulations containing such solids can be attained in inorganic matrices via mixing / stirring.

[0086] As an alternative embodiment, a three-phase recovery process can be employed to recover the solids produced by these systems and methods. Such three-phase processes as are described below can effect fine particle recovery and can further permitmodification of the fine particles during the recovery process. Using such techniques as may be familiar to skilled artisans in the field, a liquid formulation (compatibilizer alone, or polymerizable recipe by itself, or compatibilized and polymerizable recipe) flows down (and permeates / coats) a packed column, e.g., a collection of metallic or ceramic spheres. The particle-laden effluent gas stream from Stage 1, Stage 2, or from the inter-stage coupler can be directed to contact the packed column, wherein the thinly coated spheres attract the carbon solids: as the particle-laden effluent gas stream contacts the packed column of wetted spheres, the particles are either adsorbed or absorbed by the liquid disposed on the spheres. Upon exiting the packed column, the effluent stream is now almost entirely gaseous, comprising mainly hydrogen with some residual unreacted hydrocarbons, and with minimal or no suspended solid carbon particulates.

[0087] Other arrangements for removing produced solids from the system disclosed herein can be envisioned by those of skill in polymer science and technology. Similarly, those of skill in these arts will be familiar with methods for integrating the aromatic carbon solids produced by these systems into full formulations for other uses. The continuous, inexpensive, and robust systems and methods as disclosed herein for producing graphene clusters and graphitic solids unlocks multiple uses for these products as additives, composites, and as free-standing articles of manufacture, as these products are integrated with conventional or product-specific technologies in the manufacturing and material sciences arts.

[0088] While this invention has been particularly shown and described with references to preferred embodiments thereof, it will be understood by those skilled in the art that various changes in form and details may be made therein without departing from the scope of the invention encompassed by the appended claims.

Claims

CLAIMS1. A system for producing graphitic carbon solids, comprising a plasma pyrolysis reactor, an inter-stage coupler, and a solids processing column:a. wherein the plasma pyrolysis reactor comprises a microwave- energized subsystem for generating a plasma and an elongated cylinder within which the microwave-energized subsystem generates the plasma, wherein the elongated cylinder has a peripheral portion and a central portion radially, and a proximal portion and a distal portion axially, with a flow diverter positioned in the proximal portion, wherein a hydrocarbon feedgas enters the distal portion and flows in a vortical path from distal to proximal within the elongated cylinder as a first flow path, wherein the first flow path occupies the peripheral portion of the elongated cylinder;wherein the first flow path flows proximally until encountering the flow diverter at the proximal portion of the elongated cylinder, wherein the flow diverter diverts the first flow path to change directions and flow from proximal to distal, thereby forming a second flow path, and the flow diverter further directs the second flow path to flow within the central portion of the elongated cylinder;wherein microwave-energized subsystem forms a field of microwave energy within the central portion of the elongated cylinder and wherein the second flow path traverses the field of microwave energy, thereby forming a plasma from the hydrocarbon feedgas and transforming the hydrocarbon feedgas in the second flow path into an effluent stream comprising plasma-produced products, wherein the effluent stream flows distally within the elongated cylinder to exit the plasma pyrolysis reactor, and wherein the plasma-produced products comprise graphene nanoplatelets;b. wherein the inter-stage coupler is in fluid communication with the plasma pyrolysis reactor and receives the effluent stream that exits the plasma pyrolysis reactor, wherein the inter-stage coupler directs the effluent stream to enter the solids processing column and wherein the inter-stage coupler comprises a mechanism for temperature control of the graphene nanoplatelets: andc. wherein the solids processing column is in fluid communication with the inter-stage coupler and comprises an insulated processing tube that regulates therate of cooling of the graphene nanoplatelets as they pass into and through the column, thereby producing a gradual and controlled decrease in particle temperature, wherein the decrease in particle temperature converts the graphene nanoplatelets into graphitic carbon solids.

2. The system of claim 1, wherein the graphitic carbon solids comprise graphite.

3. The system of claim 2, wherein the graphitic carbon solids consist essentially of graphite.

4. The system of claim 1, wherein the graphene nanoplatelets comprise graphene clusters.

5. The system of claim 4, wherein the graphene nanoplatelets consist essentially of graphene clusters.

6. The system of claim 1, wherein the graphene nanoplatelets act as seeds to nucleate the formation of the graphitic carbon solids.

7. The system of claim 1, wherein the mechanism for temperature control comprises a mechanism for rapid acceleration of the effluent stream.

8. The system of claim 7, wherein the mechanism for rapid acceleration is a shaping structure.

9. The system of claim 8, wherein the shaping structure comprises a nozzle.

10. The system of claim 1, wherein the mechanism for temperature control comprises exposure to a cryogenic liquid.1 1. The system of claim 10, wherein the exposure effects a rapid decrease in temperature, thereby preserving a disordered graphene morphology for the graphene nanoplatelets.

12. The system of claim 1, wherein the insulated processing tube provides a long, temperature-controlled path for the graphene nanoplatelets as they pass through the solids processing column.

13. The system of claim 12, wherein the long, temperature-controlled path is substantially similar in length to the solids processing column.

14. The system of claim 12, wherein the long, temperature-controlled path is curved or spiral in shape.

15. The system of claim 1, wherein at least one of the inter-stage coupler and the solids processing column comprises an entry point for an additive to be admixed with the effluent stream.

16. The system of claim 15, wherein the inter-stage coupler provides the entry point.

17. The system of claim 16, wherein the additive comprises an oxidizing or a polar gas composition.

18. The system of claim 16, wherein the additive comprises a secondary feedstock.

19. The system of claim 18, wherein the secondary feedstock comprises a saturated hydrocarbon or an unsaturated hydrocarbon.

20. The system of claim 18, wherein the secondary feedstock comprises a heteroatom.

21. The system of claim 18, wherein the secondary feedstock in combination with the graphene nanoplatelets triggers the formation of the graphitic carbon solids.

22. The system of claim 15, wherein the solids processing column comprises the entry point.

23. The system of claim 22, wherein the additive comprises the secondary feedstock.

24. The system of claim 23, wherein the secondary feedstock comprises a saturated hydrocarbon or an unsaturated hydrocarbon.

25. The system of claim 23, wherein the secondary feedstock comprises a heteroatom.

26. The system of claim 23, wherein the secondary feedstock in combination with the graphene nanoplatelets triggers the formation of the graphitic carbon solids.

27. The system of claim 1, further comprising a collector for recovering graphitic carbon solids, wherein the collector is positioned to collect the graphitic carbon solids from a system component selected from the group consisting of the plasma pyrolysis reactor, the inter-stage coupler, and the solids processing column.

28. A method of producing graphitic carbon solids, comprising:providing system of claim 1;directing a hydrocarbon feedgas to flow in a vortical flow along a first flow path from distal to proximal within the elongated cylinder of the plasma pyrolysis reactor and along the peripheral portion of the elongated cylinder until the hydrocarbon feedgas encounters the flow diverter,wherein the flow diverter reverses the first flow path and directs it distally and centrally to form a second flow path flowing from proximal to distal within the central portion of the elongated cylinder;energizing the hydrocarbon feedgas in the second flow path with the field of microwave energy provided by the microwave-energized subsystem to form a plasma, thereby converting the hydrocarbon feedgas into the effluent stream comprising graphene nanoplatelets that exits the plasma pyrolysis reactor;directing the effluent stream into the inter-stage coupler, wherein the interstage coupler regulates the temperature of the graphene nanoplatelets entrained in the effluent stream; andpassing the effluent stream from the inter-stage coupler into the solids processing column and cooling the graphene nanoplatelets therein,wherein one or both substeps of regulating the temperature of the graphene nanoplatelets by the inter-stage coupler and / or cooling the graphene nanoplatelets by the solids processing column convert the graphene nanoplatelets into graphitic carbon solids.

29. The method of claim 28, wherein the graphene nanoplatelets comprise graphene clusters.

30. The method of claim 29, wherein the graphene nanoplatelets consist essentially of graphene clusters.

31. The method of claim 28, further comprising a step of admixing an additive to combine with the graphene nanoplatelets, wherein the step of admixing occurs in at least one of the plasma pyrolysis reactor, the inter-stage coupler, and the solids processing column.

32. The method of claim 31, wherein the step of admixing takes place in the inter-stage coupler or the solids processing column.

33. The method of claim 31. wherein the additive is an oxidizing or polar gas.

34. The method of claim 31, wherein the step of admixing produces an edge chemical modification of the solid graphene particles in the effluent.

35. The method of claim 31, wherein the step of admixing takes place by exposing the clustered graphene particles to a polar solvent.

36. The method of claim 35, wherein the polar solvent comprises an oxidizing agent or a strong acid.

37. The method of claim 35, wherein the step of admixing produces sulfonated solid graphene particles.

38. The method of claim 31, wherein the additive comprises a heteroatom.

39. The method of claim 38, wherein the heteroatom is silicon.

40. The method of claim 39, wherein the additive comprises silane or tricholorosilane, and the step of admixing produces silicon nanoparticles.

41. The method of claim 28, further comprising a step of recovering the graphitic carbon solids from the system component selected from the group consisting of the plasma pyrolysis reactor, the inter-stage coupler, and the solids processing column.

42. The method of claim 41, wherein the step of recovering takes place following the step of admixing the additive to combine with the graphene nanoplatelets.

43. The method of claim 41, wherein the step of recovering takes place via a three-phase recovery process.

44. The method of claim 41 or 42, further comprising a step of mixing into a supportive matrix the graphitic carbon solids collected by the step of recovering the graphitic solids, thereby creating a composite material comprising the graphitic carbon solids.

45. The method of claim 44, wherein the supportive matrix is an inorganic matrix.

46. The method of claim 44, wherein the supportive matrix is an organic matrix.

47. The method of claim 46, wherein the supportive matrix is an aliphatic matrix.

48. The method of claim 46, wherein the supportive matrix is an aromatic matrix.

49. The method of claim 44, wherein the step of mixing takes place by using a compatibilizer.

50. The method of claim 44, wherein the step of mixing takes place by using a surfactant- loaded aqueous spray.

51. A system for producing graphitic carbon solids, comprising a plasma pyrolysis reactor, a solids processing column, and a solids separator:wherein the plasma pyrolysis reactor comprises a microwave-energized subsystem for generating a plasma and an elongated cylinder within which the microwave-energized subsystem generates the plasma, wherein the plasma yields chemical products and a hot effluent;wherein the solids processing column is in fluid communication with the plasma pyrolysis reactor, wherein the solids processing column and wherein the hot effluent passes from the pyrolysis reactor into the solids processing column;wherein the solids processing column comprises a growth feedgas inlet supplying a growth feedgas for treating the nanoscale carbon solids to change at least one of their size and shape, thereby converting the nanoscale carbon solids into processed graphitic carbon solids, and wherein the solids processing column passes the processed graphitic carbon solids from proximal to distal to pass into the solids separator; andwherein the solids separator is in fluid communication with the solids processing column and comprises one or more separation mechanisms that separate the processed graphitic carbon solids according to at least one of size and shape to yield a plurality of product particles.

52. The system of claim 51, wherein the processed graphitic carbon solids comprise graphite.

53. The system of claim 52, wherein the processed graphitic carbon solids consist essentially of graphite.

54. The system of claim 1, wherein the nanoscale carbon solids comprise graphene clusters.

55. The system of claim 4. wherein the nanoscale carbon solids consist essentially of graphene clusters.

56. The system of claim 1, wherein the nanoscale carbon solids act as seeds to nucleate the formation of the processed graphitic carbon solids.

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