WO2025181650A1

WO2025181650A1 - Pyrolysis reactor

Info

Publication number: WO2025181650A1
Application number: PCT/IB2025/051952
Authority: WO
Inventors: Fabio Di Fonzo; Riccardo TAORMINA; Giacomo GABRIELE; Carlo PIRTI; Simone FIORINI GRANIERI
Original assignee: X Nano Srl; Fondazione Istituto Italiano di Tecnologia
Current assignee: X Nano Srl; Fondazione Istituto Italiano di Tecnologia
Priority date: 2024-02-26
Filing date: 2025-02-24
Publication date: 2025-09-04
Anticipated expiration: 2026-08-26

Abstract

The present invention relates to a pyrolysis reactor comprising a reaction chamber and a cladding shell, wherein the reaction chamber comprises an internal cavity containing at least one heating element in the form of a wire, rope, braid, bundle, cable, tape, or other intertwining composed of wires or a porous flexible element comprising fibers. The reactor of the present invention is advantageously capable of producing both graphite for lithium batteries and turquoise hydrogen efficiently, with reduced energy consumption and without causing environmental harm.

Description

Pyrolysis reactor

Field of the invention

The present invention relates to a pyrolysis reactor, specifically a pyrolysis reactor comprising a reaction chamber and a cladding shell, wherein the reaction chamber comprises an internal cavity containing at least one heating element in the form of a wire, rope, braid, bundle, cable, tape, or other intertwining composed of wires or a porous flexible element.

Prior art

Graphite is an essential component of the anode in lithium-ion batteries (lithium batteries). In recent years, its demand has increased due to the rapid growth of the electric vehicle market.

Currently, conventional methods for producing graphite for lithium batteries involve extensive exploitation (and an extensive processing) of graphite derived from petroleum coke or natural graphite extracted from mines. One of these methods specifically comprises high-temperature thermal treatment and chemical purification steps, which might be highly energy-intensive and pose environmental risks.

The process for producing pyrolytic graphite (graphite obtained through a pyrolytic process) has been known for many years, as has the process of chemical vapor deposition on a hot- wire/fiber, however, to date, no reactors have ever been described that are capable of producing graphite for lithium batteries while the production process avoids the aforementioned issues (high energy consumption and environmental risks). Ideally, such a reactor should have a production capacity ranging from several thousand to hundreds of thousands of tons per year, it should exploit hydrogen derived from the thermal cracking of gaseous hydrocarbons to generate the energy required for its operation — ideally being self- sufficient or, even better, producing excess hydrogen or electricity.

Current pyrolysis reactors for fossil or renewable hydrocarbons (such as methane) have several disadvantages. W02013/004398 describes a moving bed reactor in which carbon spheres acting as catalysts are indirectly heated through metal walls that are inductively heated by an external coil. This solution, although it is relatively efficient in removing solid carbon products, it suffers from significant material limitations.

The plasma-based approach has evolved beyond the initial work of Fulcheri in France and Monolith in the United States. The main advantage of plasma-based approaches is the extremely high temperature reached in the plasma jet (T » 2000°C) without direct contact with the reactor walls. If the electricity used to power the plasma torch comes from renewable sources, the process can be considered CCE-free. However, due to the very short contact time between the plasma torch and methane, only carbon particulate matter is typically obtained, usually in the form of carbon black, which is useful for the tire industry. US 2009/0142250 describes a reactor for producing carbon that utilizes plasma technology.

The third relevant approach found in the literature is that of the McFarland group in the United States, where liquid metals have been used to catalyze the pyrolysis reaction at T > 1000°C. Recently, the shift has been from liquid metals to molten salts to reduce costs and environmental risks. Although this solution is considered highly efficient for low-cost H2 generation based on available preliminary studies, the resulting carbon products are typically contaminated with liquid metals or residual salts. Even though this process has never been proposed for simultaneous graphite production for batteries, the high level of impurities in the carbon output of this process makes it unsuitable for use in lithium batteries unless subjected to a following intensive purification process. US20200283293 describes a reactor that decomposes hydrocarbons to obtain hydrogen hydrocarbons and carbon-based products.

Since the pyrolysis of fossil or renewable hydrocarbons (such as methane) not only produces carbon-based products but also the so-called "turquoise hydrogen", which, unlike gray hydrogen (the hydrogen typically generated during fossil fuel production), its production does not foresee the formation of CO2, a further aspect that is currently attracting market interest is the possibility of having reactors capable of obtaining large quantities of turquoise hydrogen from hydrocarbon pyrolysis, which can be directly used in industrial supply chains. To date, no reactors exist that can simultaneously produce both graphite and turquoise hydrogen. The availability of a reactor capable of simultaneously generating both graphite and turquoise hydrogen would be highly advantageous for the industrial sector, as it would enable the production of two widely used products (graphite and turquoise hydrogen) in a single reactor, without the major drawback of massive CO2 production (as a byproduct) and with significant cost and time savings.

The ability to have a reactor capable of producing graphite for lithium batteries and turquoise hydrogen efficiently, with reduced energy consumption and without causing environmental harm, is therefore a pressing market need.

Summary of the invention

The object of the present invention is therefore to provide a reactor capable of producing graphite for lithium batteries efficiently, with reduced energy consumption and without causing environmental harm.

This object is achieved by a reactor as outlined in the appended claims, whose definitions form an integral part of this description.

Brief description of the Figures

The invention will be better understood from the following detailed description of its preferred embodiments, provided by way of example and therefore not limiting, with reference to the attached Figures, wherein:

- Figure 1 shows a longitudinal section of a portion of a preferred, but non-binding, embodiment of the reactor according to the present invention;

- Figure 2 shows a comparison between the Raman spectrum of a commercial batterygrade graphite and that produced in the reactor according to the present invention;

- Figure 3 shows a spectrum obtained from an EDX spectroscopic analysis conducted on a graphite sample obtained from the reactor according to the present invention.

In the appended Figures, identical or similar elements are denoted by the same reference numerals.

Detailed description of the invention

The object of the present invention relates to a pyrolysis reactor comprising a reaction chamber comprising one or more side walls, closed at the inlet by an inlet base and at the outlet by an outlet base, wherein the inlet base is provided with at least one admission opening, and the outlet base is provided with at least one discharge opening, wherein said discharge opening is fluidically connected to a discharge section, which may optionally also comprise a regenerative heat recovery unit and/or a solids removal unit; a cladding shell that covers and surrounds the reaction chamber and preferably also the discharge section; characterized in that the reaction chamber comprises an internal cavity extending between the admission opening and the discharge opening, wherein at least one heating element is comprised within said internal cavity, which extends longitudinally with respect to the internal cavity, wherein said at least one heating element is in the form of a wire, rope, braid, bundle, cable, tape, or other intertwining composed of wires or a porous flexible element comprising fibers.

Preferably, said at least one heating element is flexible.

Preferably, said at least one heating element has a length greater than 0.05 m and comprises carbon.

Preferably, the fibers of the porous flexible element are derived from carbon paper or carbon felt and are preferably short fibers.

Figure 1 shows a longitudinal section of a portion of a preferred, but non-binding, embodiment of the reactor according to the present invention wherein the numerical references correspond to: 10 is the pyrolysis reactor, 12 is the reaction chamber, 14 is one of the side walls, 16 is the inlet base, 18 is the outlet base, 20 is the admission opening, 22 is the discharge opening, 26 is the discharge section, 28 is the cladding shell, 30 is the internal cavity, 32 is a heating element, while arrows 100 indicate the movement of hydrocarbon gas flow, arrows 102 indicate the movement of turquoise hydrogen, and arrows 104 indicate the movement of volatile carbon particles.

According to a preferred embodiment of the reactor of the present invention, the at least one heating element preferably comprises carbon (C) fibers and/or silicon carbide (SiC) fibers and/or fibers derived from expanded graphite and/or fibers (preferably short) derived from carbon paper and/or fibers (preferably short) derived from carbon felt. Alternatively, in another embodiment of the reactor according to the present invention, the at least one heating element comprises carbides, such as tantalum carbide, tungsten carbide, molybdenum carbide, or titanium carbide. Since in the lithium battery sector, and particularly in the graphite used for these batteries, metals are allowed as impurities only in ppm levels, carbon and SiC are preferred since cleaning phases in post-processing are avoided.

Envisaging the use of heating elements with the aforementioned characteristics provides the following advantages: each heating element placed inside the reaction chamber transfers heat to the gaseous hydrocarbon flow in the most efficient way possible, minimizing thermal conduction in the axial direction toward the outlet base. The advantageous shape of the at least one heating element allows to design reactors as long as several tens of meters, effectively making the reaction time/residence time an independent design parameter, which is essential when a reaction has a fixed temperature-time relationship (e.g., high temperature-short time and vice versa). The feature whereby the at least one heating element is composed of fiber bundles increases the surface area A for deposition within the reactor volume V; the electrical resistance of the at least one heating element can be easily adjusted by varying the length and the number of fibers per heating element in the form of wire, rope, braid, bundle, cable, tape, or other intertwining composed of wires or a porous flexible element comprising fibers (preferably short) derived from carbon paper or carbon felt.

Advantageously, heating elements made of C and/or SiC in the form of an isolated fiber, wire, rope, braid, bundle, cable, tape, or other intertwining composed of wires or a porous flexible element comprising fibers (preferably short) derived from carbon paper or carbon felt can be used as a heating element by directly passing current through them. In this case, a partially graphitized carbon shell will form on the outer layer of the fiber, wire, rope, braid, bundle, cable, tape, or porous flexible element. Allowing this graphite layer to grow will form a graphite cylinder coaxial with the central fiber.

The crystalline quality of the graphite obtained from the reactor according to the present invention can be evaluated using Raman spectroscopy, specifically by analyzing the ratio between the D and G peaks of graphite, located at 1350 cm ¹ and 1580 cm respectively. A value lower than ID/IG < 0.1 can be considered an indicator of high crystallinity. Figure 2 shows the comparison between the Raman spectrum of a commercial battery-grade graphite (upper line) and that produced in the reactor according to the present invention (lower line). From the aforementioned figure, it is evident that the two spectra are substantially identical and that they have the same ratio.

To regulate the ratio between the deposition of solid carbon/graphite on the heating elements and the particulate formed in the gas phase (i.e., soot), it is important to control the ratio between the available surface area for deposition and the reactor volume, i.e., the A/V ratio. This can be achieved by employing a large number of fibers that make up the heating element so that the A/V ratio is greater than 1, preferably greater than 100. The carbon fibers can be used as isolated elements or in the form of bundles, ropes, or other configurations.

The fibers can be arranged in various ways, such as longitudinally in a compact hexagonal matrix, in concentric circular matrices with or without a central fiber/rope, tangentially wound around longitudinal insulating bars, suspended in a U-shape from a single wing, or as porous flexible elements comprising fibers.

Another advantage of using a wire, rope, braid, bundle, cable, tape, or other intertwining composed of wires or a porous flexible element comprising fibers (preferably short) derived from carbon paper or carbon felt as a heating element is that they can also serve a structural function by maintaining the two bases of the reaction chamber at a constant distance.

Preferably, the distance between each heating element should be calculated to ensure enough space for the growth of the graphite layer while leaving sufficient space for the passage of gaseous hydrocarbons through the array of heating elements, ensuring homogeneous coverage along the entire length of each heating element. As an example, using a heating element consisting of a rope with a diameter of 0.5 mm, a graphite coating of 15 mm is required, thereby determining a spacing greater than 30.5 mm between the centers of the heating elements.

According to a preferred embodiment of the reactor of the present invention, the reaction chamber preferably has a polygonal shape, preferably chosen from cylindrical, parallelepiped, cubic, pyramidal, conical, spherical, a combination of these, or another suitable shape.

According to a preferred embodiment of the reactor of the present invention, the cladding shell is preferably made of steel and can be cooled by an external system outside the reactor.

According to an alternative embodiment of the reactor of the present invention, the reactor preferably comprises two cladding shells, one covering and surrounding the reaction chamber and another covering and surrounding the discharge section.

According to a preferred embodiment of the reactor of the present invention, the at least one heating element is preferably heated by the Joule effect. As known to a person skilled in the art, the Joule effect can be briefly described as the phenomenon whereby a conductor of any type, when traversed by an electric current (whether direct or alternating), dissipates part of the supplied electrical energy into other forms of energy, such as heat. According to a preferred embodiment of the reactor of the present invention, the at least one heating element is preferably heated by the Joule effect due to the heat dissipated by the electric current passing through the heating element. Preferably, the heating element is heated directly by electricity or indirectly through electromagnetic induction.

According to a preferred embodiment of the reactor of the present invention, the reaction chamber and the discharge section are preferably coaxially and serially arranged with respect to each other. According to an alternative embodiment of the reactor of the present invention, the reaction chamber and the discharge section are preferably misaligned with respect to each other.

According to a preferred embodiment of the reactor of the present invention, the internal through cavity of the reaction chamber is preferably coaxial and longitudinal with respect to the cladding shell.

According to an alternative embodiment of the reactor of the present invention, the heating element is optionally a carbon accretion core. That is, it is an element that, acting as a core, allows the deposition of a carbonaceous layer on itself.

According to a preferred embodiment of the reactor of the present invention, the number of heating elements is preferably proportional to the volume of the reaction chamber. This feature advantageously allows for the modulation of the ratio between the carbon deposited on the heating element and the carbon nucleated in the gas phase (volatile carbon particles) present inside the reaction chamber.

According to a preferred embodiment of the reactor of the present invention, the heating element is in the form of a wire, rope, braid, bundle, cable, tape, or porous flexible element, preferably having a length between 0.05 m and 1000 m, even more preferably between 0.5 m and 200 m, and most preferably between 0.5 m and 10 m.

According to a preferred embodiment of the reactor of the present invention, the heating element preferably comprises a plurality of wires, ropes, braids, bundles, cables, tapes, or other intertwinings composed of wires or porous flexible elements, arranged substantially parallel to each other and anchored at one end to the inlet base and at the opposite end to the outlet base.

According to an alternative embodiment of the reactor of the present invention, the heating element is in the form of a wire, rope, braid, bundle, cable, tape, or porous flexible element, wherein both ends of the heating element are preferably anchored either to the inlet base or to the outlet base, and the heating element extends longitudinally within the internal cavity following a substantially U-shaped path.

According to an alternative embodiment of the reactor of the present invention, the heating element is in the form of a wire, rope, braid, bundle, cable, tape, or porous flexible element and preferably extends longitudinally within the internal cavity following a substantially serpentine path, preferably intersecting multiple times along its path with both the inlet base and the outlet base, while the ends of the heating element are preferably anchored either to the inlet base, to the outlet base, or to both.

According to an alternative embodiment of the reactor of the present invention, multiple heating elements are present inside the internal cavity, arranged either in series or in parallel.

According to a preferred embodiment of the reactor of the present invention, the internal cavity of the reaction chamber is preferably surrounded by at least one thermally insulating layer. Preferably, the thermal insulating layers are two, and they are preferably made of thin carbon felt, carbon fabric, or zirconia felt.

According to a preferred embodiment of the reactor of the present invention, the discharge section preferably comprises a solids removal system, even more preferably a cyclone or a bag filter.

According to a preferred embodiment of the reactor of the present invention, between the cladding shell and the reaction chamber (and optionally also the discharge section), there preferably is a channel for transporting at least one gaseous hydrocarbon or gas for pyrolysis, wherein the channel opens at the admission opening of the inlet base of the reaction chamber. Preferably, though not exclusively, the channel extends longitudinally, coaxial, and parallel to the reaction chamber (and optionally also to the discharge section).

According to a preferred embodiment of the reactor of the present invention, the regenerative heat recovery unit comprises a duct that extends in a substantially spiral path within the regenerative heat recovery unit, wherein said duct opens into the channel between the cladding shell and the reaction chamber (and optionally also the discharge section). Preferably, at least one gaseous hydrocarbon or gas for pyrolysis flows through and is thus transported inside the duct and subsequently into said channel.

The present invention therefore proposes a pyrolysis reactor for the production of fossil or renewable turquoise hydrogen and graphite for lithium batteries from gaseous hydrocarbons or gases for pyrolysis, such as natural gas, methane, ethylene, and acetylene.

Preferably, the gaseous hydrocarbons used in the reactor of the present invention are either of fossil origin (such as natural gas, methane, ethane, other gaseous alkanes, ethylene, acetylene) or derived from renewable sources (such as biogas, biomethane, syngas - synthesis gas - for example).

The hydrogen, the main byproduct of the process, can advantageously be used to power the process occurring within the reactor itself or be sold on the market. Graphite can advantageously be used as an anode material in lithium-ion batteries or for any other common application of synthetic or natural graphite.

The advantages of the claimed technology are numerous. First, the pyrolysis reactor according to the present invention can produce graphite directly from hydrocarbons, eliminating the need for extensive processing and reducing environmental impact. Second, the reactor of the present invention produces hydrogen as a byproduct, which can be used as a clean fuel for various applications, including fuel cell power generation and as a raw material for chemical production. Third, the reactor of the present invention is scalable and can be used at various capacities to meet market demands, operating with a high-pressure inlet and a low- to high-pressure outlet, making it easily integrable into existing facilities.

Furthermore, the reactor design allows flexibility in the selection of raw materials, enabling the use of various hydrocarbons, including those derived from renewable sources such as biomass and exhaust gases. This feature allows for the production of graphite from sustainable and low-cost raw materials.

The reactor of the present invention thus advantageously provides an efficient and sustainable alternative for the production of graphite and turquoise hydrogen (which can be widely adopted for a broad range of applications).

Graphitic carbon, in addition to its use in lithium batteries, has a wide range of other 5 industrial applications, including its use as an electrode in steel production, as a lubricant, and as an active intercalation material for energy storage. Current methods for producing graphite are energy-intensive and highly expensive. The reactor of the present invention advantageously provides an efficient and cost-effective alternative for graphite production. 0 The reactor of the present invention preferably and advantageously operates by heating natural gas to high temperatures in a reaction chamber with a large reactive surface area, causing its decomposition into its constituent elements: carbon and hydrogen. The carbon atoms then combine to form graphite due to the high temperature of at least one heating element present in the chamber. Hydrogen is released as a byproduct and can be captured 5 and used as a fuel source. The resulting graphite is advantageously of high purity and can be easily collected from the heating element. Figure 3 shows a spectrum obtained from an EDX spectroscopic analysis conducted on a graphite sample obtained from the reactor of the present invention. From this spectrum, it is possible to observe that the graphite is composed almost entirely of carbon (C) (left peak), with minimal oxygen (O) impurities (right peak). 0 The following Table 1 shows the results of an ICP-OES (Inductively Coupled Plasma Optical Emission Spectroscopy) analysis conducted on a graphite sample produced by the reactor of the present invention: 5 Table 1: ICP-OES Analysis of Graphite Produced by the Reactor According to the Present Invention.

The data presented in Table 1 clearly demonstrate that the graphite advantageously does not contain impurities that could be potentially harmful for applications such as lithium batteries.

In summary, the reactor of the present invention represents a breakthrough in graphite production, particularly for lithium-ion batteries. Its advantages over conventional methods include reduced environmental impact, the production of hydrogen as a clean fuel, scalability, and flexibility in raw material selection. These advantages make this technology a promising candidate for the future of sustainable graphite production, especially for lithium-ion batteries.

To design a reactor according to the present invention that can operate at high pressure, at temperatures above 1000°C, and for extended periods, the reaction chamber is preferably characterized by a cylindrical geometry with the following features:

- Radial design: The temperature of the outer walls of the cladding shell is preferably kept below 800°C. This is preferably achieved through a sequence of thermally insulating layers. A first thermally insulating layer, the one closest to the at least one heating element, is preferably of low porosity and can be made of thin carbon felt, carbon fabric, or zirconia felt (with or without a coating layer to seal the porosity of this layer exposed to the heating elements). This thermally insulating layer also serves to direct the gaseous hydrocarbons axially. A second thermally insulating layer (more external than the first) preferably functions to lower the temperature to 800°C, allowing the reaction chamber to be enclosed within a preferably cylindrical steel cladding shell without the need for fragile ceramics, glass, or graphite. Even though the operating temperature of the cladding shell is relatively high, it does not bear any mechanical stress since the reaction chamber is at the same pressure as the channel located between the cladding shell and the reaction chamber (and optionally also the discharge section). The temperature of this channel is preferably controlled to prevent any carbon deposits inside the channel itself. The lower limit is set by the regenerative heat recovery from the exhaust gases. A third thermally insulating layer (radially more external than the second) can be made of fiberglass or any other high- performance insulating material with an operating temperature below 1000°C. A fourth thermally insulating layer (radially more external than the third) is externally surrounded by the cladding shell. Increasing the thickness of the insulating layers allows for the reduction of the operating temperature of the cladding shell;

- Longitudinal design: Since the radial arrangement and the diameter of each layer are preferably defined by the previous considerations, the length of the reactor is preferably determined so that the length is greater than the diameter, ensuring better graphite distribution and increasing the residence/contact time between the gaseous hydrocarbons and the at least one heating element. In this regard, C/SiC fiber/rope heating elements preferably offer an almost unlimited residence/contact time, as they are available in lengths exceeding 100 m;

- The inlet base and the outlet base of the reaction chamber are preferably made of a flange composed of steel/graphite/titanium/tungsten/molybdenum/tantalum or refractory ceramics such as alumina, zirconia, yttria, magnesia, and their compounds, incorporating a series of holes for the distribution of gaseous hydrocarbons into and out of the reaction chamber;

- The cladding shell is preferably closed at the top by a flange (flat or hemispherical) capable of withstanding the internal pressure of the reactor and is preferably equipped with electrical feedthroughs. The entire internal surface of the flange is preferably thermally insulated. The geometry is preferably designed so that the preheated gaseous hydrocarbons expand in the space between the flange and the inlet base of the reaction chamber and are directed towards the holes in the inlet base to enter the reaction chamber.

Inside the reaction chamber, the gaseous hydrocarbons are then forced to expand within the internal cavity and slow down their movement speed. Within the internal cavity, the flow path of these gaseous hydrocarbons toward the outlet base is hindered by the presence of the at least one heating element, on which the decomposition reaction of the gaseous hydrocarbons takes place, generating hydrogen and releasing carbon particles.

According to a preferred embodiment of the reactor of the present invention, the reactions occurring inside the internal cavity of the reaction chamber may lead to the formation of solid particulate matter of various sizes. This may be intentional or a side reaction when the primary objective is the deposition of graphite on the at least one heating element. In any case, this particulate matter must be removed from the hydrocarbons exiting the reaction chamber and passing through the discharge section before the latter can be reused in any further latter processing. An example of a filter for solid particulate matter may include a cyclone, a bag filter, or similar systems.

According to a preferred embodiment of the reactor of the present invention, the discharge section preferably also comprises a regenerative section that recovers the heat contained within the discharge section by preheating the gaseous hydrocarbons that will enter the reaction chamber through the channel between the cladding shell and the reaction chamber within the reaction chamber. The preheating temperature is preferably set at a level that prevents any chemical reaction from occurring within the channel. However, if thermally induced chemical reactions within the channel are not an issue, then the preheating temperature should preferably be as high as technically allowed by the regenerative section. Within the regenerative section, the gaseous hydrocarbons exiting the reaction chamber (at high temperatures) and the gaseous hydrocarbons entering the reactor preferably flow in countercurrent to maximize heat recovery efficiency.

According to a preferred embodiment of the reactor of the present invention, the temperature of the internal cavity of the reaction chamber is preferably controlled by an external power supply. As is well known to those skilled in the art, the decomposition reaction of hydrocarbons occurs above 1000°C, and beyond this temperature, hydrocarbons decompose into carbon and hydrogen. When this occurs inside the internal cavity of the reactor according to the present invention, part of the carbon is deposited on the at least one heating element, while some is dispersed in the form of volatile carbon particles. These carbon particles are preferably subjected to the following process: they are carried toward the outlet base and then toward the discharge section, where filtration systems can be employed to collect the volatile carbon particles.

When the reactor of the present invention is used for hydrogen production, the reaction temperatures inside the internal cavity of the reaction chamber are preferably lower, and the reactor preferably comprises a smaller number of heating elements, ensuring that the residence time of the gaseous hydrocarbons within the reaction chamber is sufficient to achieve a high decomposition yield. In this mode, the production of volatile carbon particles increases, and the primary result of the process is gaseous hydrogen. When the reactor of the present invention is used for hydrogen production, it comprises a smaller number of heating elements to promote the formation of volatile carbon particles and reduce deposition on the heating elements. This is because volatile carbon particles can be expelled from the reactor, thereby extending the maintenance intervals of the reactor.

Conversely, when the reactor of the present invention is used for the production of graphite for lithium batteries, it preferably comprises a larger number of heating elements with a high surface area. Additionally, the reaction chamber preferably reaches higher temperatures to promote the graphitization of the carbon particles deposited on the heating elements, forming a uniform coating on them. This coating can be easily removed when the reactor is regenerated to obtain graphite, which can be used in various applications. The graphite can optionally be collected at the bottom of the reaction chamber and expelled, allowing the reactor to operate continuously.

The reactor of the present invention advantageously allows for the production of hydrogen or graphite while emitting low amounts of greenhouse gases. Moreover, if the gaseous hydrocarbons introduced into the reactor are controlled and if the process is optimized for the complete conversion of gaseous hydrocarbons into turquoise hydrogen and graphite, CO2 emissions can be completely eliminated.

The reactor of the present invention is therefore advantageously capable of efficiently producing both graphite for lithium batteries and turquoise hydrogen, with reduced energy consumption and without causing environmental harm. As described above, the preferred use of the reactor according to the present invention is the production of both graphite for lithium batteries and turquoise hydrogen. However, the reactor of the present invention can alternatively be used for the production of graphite suitable for any application, such as for sodium batteries or, more generally, for any other use of graphite.

Claims

1. Pyrolysis reactor (10) comprising a reaction chamber (12) comprising one or more side walls (14) closed at the inlet by an inlet base (16) and at the outlet by an outlet base (18), wherein the inlet base (16) is provided with at least an inlet opening (20) and the outlet base (18) is provided with at least an outlet opening (22), wherein said outlet opening (22) is fluidically connected to a discharge section (26) which may optionally also comprise a regenerative heat recovery unit and/or a solids removal unit; a cladding shell (28) that covers and surrounds the reaction chamber (12) and preferably also the discharge section (26); characterized by the fact that the reaction chamber (12) comprises an internal cavity (30) passing through the inlet opening (20) and the outlet opening (22), wherein in said internal cavity (30) is comprised at least a heating element (32) extending longitudinally with respect to the internal cavity (30), wherein said heating element (32) is in the form of wire or rope or braid or bundle or cable or tape or other intertwining composed of wires or porous flexible element comprising fibres, wherein said at least one heating element (32) has a length of more than 0.05 m and comprises carbon.

2. Reactor (10) according to claim 1, wherein the fibres of the porous flexible element are derived from carbon paper or carbon felt and are preferably short fibres.

3. Reactor (10) according to any one of claims 1 to 2, wherein said at least a heating element (32) is heated by the Joule effect.

4. Reactor (10) according to any one of claims 1 to 3, wherein the reaction chamber (12) and the discharge section (26) are placed coaxially and in series with each other.

5. Reactor (10) according to any one of claims 1 to 4, wherein the at least a heating element (32) is a carbonic accretion core.

6. Reactor (10) according to any one of claims 1 to 5, wherein the number of heating elements (32) is proportional to the volume of the reaction chamber (12).

7. Reactor (10) according to any one of claims 1 to 6, wherein said at least a heating element (32) is in the form of wire or rope or braid or bundle or cable or tape or other intertwining composed of wires or porous flexible element having a length comprised between 0.05 m and 1000 m.

8. Reactor (10) according to any one of claims 1 to 7, wherein said at least a heating element (32) comprises a plurality of wire or ropes or braids or bundles or cables or tapes or other intertwinings composed of wires or porous flexible elements arranged substantially parallel to each other and anchored at one end thereof to the inlet base (16) and at another end thereof to the outlet base (18).

9. Reactor (10) according to any one of claims 1 to 7, wherein said at least a heating element (32) is in the form of wire or rope or braid or bundle or cable or tape or other intertwining composed of wires or porous flexible element wherein both ends of the heating element (32) are anchored to either the inlet base (16) or the outlet base (18), wherein the heating element (32) extends longitudinally within the internal cavity (30) following a substantially U-shaped path.

10. Reactor (10) according to any one of claims 1 to 7, wherein said at least a heating element (32) is in the form of wire or rope or braid or bundle or cable or tape or other intertwining composed of wires or porous flexible element and extends longitudinally within the internal cavity (30) following a substantially serpentine path.

11. Reactor (10) according to any one of claims 1 to 10, wherein within the internal cavity (30) there are several heating elements (32) placed between them either in series or in parallel.

12. Reactor (10) according to any of claims 1 to 11, wherein the internal cavity (30) of the reaction chamber (12) is surrounded by at least a thermally insulating layer.

13. Reactor (10) according to any one of claims 1 to 12, wherein said discharge section (26) comprises a solids removal system.

14. Reactor (10) according to any one of claims 1 to 13, wherein between the cladding shell (28) and the reaction chamber (12) and optionally also the discharge section (26) there is a channel, for transporting at least a gaseous hydrocarbon, wherein the channel flows at the admission opening (20) of the inlet base (16) of the reaction chamber (12).