Pyrolytic carbon particle comprising at least two layers of different surface morphology

Abstract

The present invention comprises a pyrolytic carbon particle, which is obtained by a thermal decomposition of hydrocarbons, and said pyrolytic carbon particle has the following properties: - Carbon content 98 to 99.99 wt.-%, - Particle size from 0.1 to 10 mm, - Ash content 0 to 2 wt.-%, - Specific surface area 5 to 25 m2 / g, - Median pore diameter from 0.005 to 1 µm, and wherein said pyrolytic carbon particle comprises at least two layers of pyrolytic carbon having different carbon morphologies, wherein each morphology is defined by the following parameters: - e-module being in the range of 5 to 35 GPa and - hardness being in the range of 0.2 to 5 GPa, - L-parameter of colour from 10 to 45 and wherein at least one of the parameter of a first morphology of a first layer of pyrolytic carbon deviates from 20 to 300% of the respective parameter of a second morphology of a second layer of pyrolytic carbon, wherein the first layer and the second layer are adjacent to each other and wherein the thickness of each layer is 1 µm to 5 mm.

Description

[0001] Anisotropic pyrolytic carbon particle comprising at least two layers of different surface morphology Description The present invention comprises a pyrolytic carbon particle, which is obtained by a thermal decomposition of hydro- carbons, and said pyrolytic carbon particle has the following properties: (i) Carbon content 98 to 99.99 wt.-%, (ii) Particle size from 0.1 to 10 mm, (iii) Ash content 0 to 2 wt.-%, (iv) Specific surface area 5 to 25 m2 / g, (v) Median pore diameter from 0.005 to 1 µm, and wherein said pyrolytic carbon particle comprises at least two layers of pyrolytic carbon having different carbon surface morphologies, wherein each morphology is defined by the following parameters: e-module being in the range of 5 to 35 GPa and hardness being in the range of 0.2 to 5 GPa, and L-parameter of colour from 10 to 45 and wherein at least one of the parameter of a first morphology of a first layer of pyrolytic carbon deviates from 20 to 300% of the respective parameter of a second morphology of a second layer of pyrolytic carbon, wherein the first layer and the second layer are adjacent to each other. In addition, the present invention comprises a process of producing said anisotropic pyrolytic carbon particle which comprises at least two layers of pyrolytic carbon having different carbon surface morphology by decomposition of hydrocarbons in a fixed, fluidized or moving bed at a pressure of 1 to 30 bara (bar absolute) and a temperature of 800 to 1500°C and a hydrocarbon concentration in the feed of 2.5 to 100 vol.-%, wherein the decomposition is con- ducted stepwise with at least two different, optionally alternating, process conditions; wherein one of the at least two different process conditions differ in at least one of the following process parameters to the other process condition: at least 20 °C difference in temperature at least 100 mbar difference in pressure at least 5 vol.-% difference in hydrocarbon concentration and wherein the at least one process condition is kept until a thickness of the pyrolytic layer of said carbon morphol- ogy of 1 µm to 5 mm. State of the art In methane pyrolysis a carbonaceous material is produced which could be used in several applications. One of the most lucrative applications is the usage in the production of electrodes for the aluminum and steel production. In the aluminum and steel production processes the electrodes are subjected to high levels of thermal stress, resulting in a risk for the formation of thermal cracks. The high thermal expansion coefficient of isotropic carbon makes it suscepti- ble to the formation of cracks during thermal treatment. The formation of thermal cracks comes along with several drawbacks like reduced lifetime of the electrodes, higher gross carbon consumption rates, and thus, higher overall CO2 emissions. Hence, the reduction of thermal cracks is an important lever to optimize the economical as well as ecological perfor- mance of the aluminum and steel production processes. An important factor for the reduction of thermal cracks is the quality of the raw material used to produce the electrodes. A high resistance against the formation of thermal cracks can be achieved by using anisotropic carbon as a raw material. The term methane pyrolysis covers a wide range of different process technologies. The best known and most ad- vanced of these are: plasma pyrolysis, pyrolysis in a metal melting & metal salt melting reactor, moving bed & fluid- ized bed and fixed bed (catalytic and non-catalytic) processes, and pyrolysis via partial combustion. They differ in the form of the energy used (thermal, electrical, etc.), the process conditions (temperature, pressure, etc.), the catalysts and / or auxiliary materials used and the process flow. The solid carbon type generated in the methane pyrolysis depends on the reaction conditions, reactor and heating technology. Plasma processes yield carbon black, metal melting & metal salt melting processes yield carbon powder and dense granular carbon is obtained from thermal decomposition in fixed, moving or fluidized bed reactors. Moving and fluidized bed reactors for methane pyrolysis are disclosed for example in US 2,982,622, US 2022 / 0152568, US 2021 / 0331918, WO 2023 / 57242. For example, to produce carbon electrodes for the aluminum or steel industry dense granular pyrolytic carbon can be used to substitute or blend standard petroleum coke. WO 2020 / 016186 discloses the use of pyrolytic carbon in blend compositions with petroleum coke for electrodes, especially anode for the aluminum production. WO 2024 / 022909 discloses the use of pyrolytic carbon obtained by deposition of pyrolytic carbon on a petroleum coke carrier material in a fixed, moving or fluidized bed at temperatures > 1000°C for controlling soil-borne plant pathogenic fungi. US 2024055607 discloses a carbon material composition containing a blend of different carbon materials based on graphites as an active material for a negative electrode for a lithium-ion secondary battery. Up to now, no anisotropic dense / granular pyrolytic carbon obtained from thermal decomposition of hydrocarbons in fixed, moving or fluidized bed reactors is disclosed. Thus, there is a need for anisotropic pyrolytic carbon particles for electrode applications. Task It is an object of the present invention to provide pyrolytic carbon particles with different pyrolytic carbon layers prop- erties / morphology and thus, providing anisotropic pyrolytic carbon particles. Another object of the present invention to find a way to control anisotropy of pyrolytic carbon obtained by a methane pyrolysis in a fixed, fluidized or moving bed that yield dense pyrolytic carbon with less smooth surface morphology. Another objective of the invention is to utilize pyrolytic carbon as substitute of petroleum coke. Another objective of the invention is to utilize pyrolytic carbon for the use in electrode, particularly for steel and aluminum production. Invention The present invention relates to a pyrolytic carbon particle, which is obtained by a thermal decomposition of hydro- carbons, and said pyrolytic carbon particle has the following properties: - Carbon content 98 to 99.99 wt.-%, - Particle size from 0.1 to 10 mm, - Ash content 0 to 2 wt.-%, - Specific surface area 5 to 25 m2 / g, - Median pore diameter from 0.005 to 1 µm, and wherein said pyrolytic carbon particle comprises at least two layers of pyrolytic carbon having different carbon morphologies, wherein each morphology is defined by the following parameters: - e-module being in the range of 5 to 35 GPa and - hardness being in the range of 0.2 to 5 GPa, - L-parameter of colour from 10 to 45 and wherein at least one of the parameter of a first morphology of a first layer of pyrolytic carbon deviates from 20 to 300% of the respective parameter of a second morphology of a second layer of pyrolytic carbon, wherein the first layer and the second layer are adjacent to each other. In addition, the present invention comprises a process of producing said anisotropic pyrolytic carbon particles which comprise at least two layers of pyrolytic carbon having different carbon morphology by decomposition of hydrocar- bons in a fixed, fluidized or moving bed at a pressure of 1 to 30 bar and a temperature of 800 to 1500°C and a hydro- carbon concentration in the feed of 2.5 to 100 vol.-%, wherein the decomposition is conducted stepwise in at least two different, optionally alternating, process conditions; wherein one of the at least two different process conditions differs in at least one of the following process parameters to the other process condition: at least 20 °C difference in temperature at least 100 mbar difference in pressure and / or at least 5 vol.-% difference in hydrocarbon concentration in the feed, and wherein the respective process condition is kept until a thickness of the pyrolytic layer of said carbon morphology of 1 µm to 5 mm is reached. Surprisingly, the morphology of the surface of the pyrolytic carbon could be varied in a range from smooth, over rough to coral by adjusting the process conditions, e.g the conversion rate by pressure and temperature of the me- thane pyrolysis in a fixed, fluidized or moving bed. By controlling the morphology, the properties of the pyrolytic car- bon can be controlled. By changing, preferably by alternating, the process conditions (for example: pressure, temper- ature, hydrocarbon concentration) carbon layers with different properties can be produced. The changed process conditions could either be achieved by changing, preferably by alternating the operation condi- tions in single fixed, fluidized or moving bed reactors or, alternatively, by the usage of two or multiple reactors con- nected in series, operated at different, but fixed operation conditions per reactor. Methods for determining the parameters D / G ratio oder (ID / IG) ratio Definition: The ratio of the intensities of the D-band (1350 cm-1) and the G-band (1580 cm-1) in the Raman spectrum Reference: ASTM E 3220:2025: Standard Guide for Characterization of Graphene Flakes, 2025 URL: E3220 Standard Guide for Characterization of Graphene Flakes Median pore diameter (volume) Definition: The median of the pore size distribution is the pore diameter at which 50% of the total cumulative pore volume is smaller and 50% is larger. Reference: ISO 15901-1:2016. Pore size distribution and porosity of solid materials by mercury porosimetry and gas adsorption - Part 1: Mercury porosimetry URL: ISO 15901-1:2016(en), Evaluation of pore size distribution and porosity of solid materials by mercury porosime- try and gas adsorption — Part 1: Mercury porosimetry Lc value Definition: The Lc value is the average stack height - i.e. the average extension of a crystalline region perpendicular to the graphene plane (c-axis of the graphite structure). Lc is the length perpendicular to the reflecting planes in XRD patterns. Reference: ASTM D5187-21. Standard Test Method for Determination of Crystallite Size (Lc) of Calcined Petroleum Coke by X-Ray Diffraction, 2021 URL: D5187 Standard Test Method for Determination of Crystallite Size (Lc) of Calcined Petroleum Coke by X-Ray Diffraction Crystallite size (La) Definition: La denotes the lateral extension of individual, coherently scattering domains in the plane of the graphene layers. Für die Bestimmung des La-Wertes in kohlenstoffbasierten Materialien gibt es keine äquivalente Norm zur Norm ASTM D5187 für die Bestimmung des LC-Wertes. Die Methode zur Ermittlung von La orientiert sich an der Methode, die in Biscoe & Warren beschrieben wird. Reference: Biscoe, J., & Warren, B. E. (1942). An X‐ray study of carbon black. Journal of Applied Physics, 13(6), 364-371. Particle size Definition: The particle size is the diameter of an idealized sphere that corresponds to the real, irregularly shaped one. It corresponds to the smallest sieve perforation diameter through which the particle fits through. Reference: [1] DIN 66165-1:2022-06. Partikelgrößenanalyse - Siebanalyse - Teil 1: Grundlagen, 2022 [2] DIN 66165-2:2016-08. Partikelgrößenanalyse - Siebanalyse - Teil 2: Durchführung, 2016 URL: Siebanalyse Unterschiedliche Siebmethoden für vielfältige Anwendungen Thickness of shell Definition: The shell thickness is the thickness of the layer of pyrolysis carbon that is deposited on a carrier particle and completely or partially covers the carrier particle. The method for determining the layer thickness is based on the ASTM B487 standard. Reference: ASTM B487. Standard Test Method for Measurement of Metal and Oxide Coating Thickness by Micro- scopical Examination of Cross Section, 2013 URL: ASTM-B-487-yr-87-R-13.pdf H2 / C1+ ratio Definition: H2 / C1+ ratio is the ratio of the mole fraction of dilution hydrogen to the mole fraction of hydrocarbons in the gaseous feed stream of the reactor. For ideal gases, the mole fractions of the mixture components are identical to the volume fractions. These parameters were measured with a micro GC, Agilent Technologies, type 490 Micro GC. Carbon content Definition: The carbon content of a carbonaceous material is the ratio of the mass of carbon contained in relation to the total mass of the sample. Determination method: CHNS method Reference: Hendrik Wetzel. CHNS-ANALYSE / O-ANALYSE, 2025 URL: CHNS-O-Analyse - Fraunhofer IAP Ash content Definition: The ash content is the mass fraction of the non-combustible residues after combustion of the sample un- der precisely defined conditions (temperature, air supply, duration). Reference: ISO 1172. Kohle und Asche - Asche URL: ISO-1171-2010.pdf Surface concentration of metallic elements Definition: The elemental composition of the sample surface, expressed in weight-% relative to the total mass of the analyzed sample. Determination method: Energy dispersive X-ray spectroscopy (EDX) in combination with scanning electron micros- copy (SEM). The raw signal of EDX is the count rate per peak. The evaluation software translates this to the surface concentration in % by weight. Reference: ASTM F1375-92(2020). Standard Test Method for Energy Dispersive X-Ray Spectrometer (EDX) Analy- sis of Metallic Surface Condition for Gas Distribution System Components, 2020. URL: F 1375 - 92 (2020).pdf Trace component concentration in the gas phase Definition: Components that occur in a carrier gas mixture in very low concentrations. Determination method: In the FTIR technique, a Michelson interferometer records an interferogram of the intensity of broadband infrared (IR) radiation. By applying a Fourier transform to this interferogram across a wide range of wave- lengths, a spectrum is generated that comprises the spectral signatures of the gaseous components present in the measurement path. Analyzing these spectral signatures allows for to determine the concentrations of many different components simultaneously using the FTIR system. Reference: DIN EN 15483:2009-02. Luftqualität Messungen in der bodennahen Atmosphäre mit FTIR-Spektroskopie, 2008. URL: ISO-14577-1-2015.pdf L value Definition: The L value (luminance) is a measure of the brightness of a surface in the CIELAB color space. Determination method: The reflectivity (luminance) is determined using luminance meters. Reference: ISO / CIE 19476:2014(en). Characterization of the performance of illuminance meters and luminance me- ters, 2014 URL: ISO / CIE 19476:2014(en), Characterization of the performance of illuminance meters and luminance meters e-module (Young modulus) & hardness Definition: The modulus of elasticity is a material-physical parameter that indicates the linear relationship between stress and deformation in the elastic (reversible) deformation range. Determination method: The hardness and modulus of elasticity of thin layers of pyrolysis carbon are measured using nanoindentation. Reference: DIN EN ISO 14577-1. Metallische Werkstoffe– Instrumentierte Eindringprüfung zur Bestimmung der Härte und anderer Werkstoffparameter– Teil1: Prüfverfahren, 2024 URL: ISO-14577-1-2015.pdf Definitions C1 stands for methane. C1+ stands for all hydrocarbons having one or more C-atoms in the molecule. C2+ stands for all hydrocarbon having two or more C-atoms in the molecule. The (total) reactor feed stream includes both the external feed stream and the internally recycled hydrogen-contain- ing product stream. Deposition rate: The definition of the carbon deposition rate, sometimes also referred to as carbon growth rate, depends on the reac- tor type and is defined in the following: The symbols and indices used are shown in Table 1. Table 1. Symbols and indices used for describing carbon deposition and growth rates. Symbol Description^^^^,ௗ^^^^^௧^^^ Carbon deposition rate [molC / s]^^^^ுସ,^ Molar flow [molC / s]^^ Conversion rate [-]^^^ ^,ௗ^^^^^௧^^^ Carbon deposition rate [g / s]^^^ Molar mass [g / mol]^^^^ Carbon deposition [g / g]Δ^^^ Carbon mass increase [g]^^^ Carbon mass [g]^^^^^ Carbon deposition rate in [g / g*s]τ Time unit [s]^^^^^^^ Carbon deposition rate (per reference time unit) [-] or in [wt.%]V Reactor volume [m3]Indices Description 0 Particle before pyrolysis or state feed gas 1 Particle after pyrolysis or state in pyrolysis gas in Reactor inlet ref Reference (e.g. time unit) The carbon deposition rate in [mol,C / s] results from the molar flow of CH4 in the feed gas and the conversion rate: ^^^^,ௗ^^^^^௧^^^ = ^^^^ுସ,^ ⋅ ^^(^^,^^,^^^ , ^^^^^^%ுଶ,^, ^^^^^^%^ுସ,^) 1Considering the molar mass of atomic carbon leads to the carbon deposition rate in [g,C / s]: ^^^ ^,ௗ^^^^^௧^^^ = ^^^ ^,ௗ^^^^^௧^^^ ⋅ ^^^ 2The CH4 conversion rate is ^^^^ுସ,^ − ^^^^ுସ ^^^^^ = ,^^^^ = 1 − ^ுସ,^3^ுସ,^ ^^^ ^ுସ,^The carbon deposition in [g / g] is defined as:Δ^^^^^^ = ^^^ 4^The carbon deposition rate in [g / (g*s)] follows from the initial mass and the carbon deposition rate in [mol,C / s]: ^^^^^^^^ = ^,ௗ^^^^^௧^^^^^ 5^The total increase in carbon mass Δ^^^ = ^^^ ^,ௗ^^^^^௧^^^ ⋅ τ 6Considering the reactor volume ^^ and the reactor type specific reference residence time leads to the carbon tion rate per reference time unit in [-]: ఛ^^^Δ^^ ^^^^^,^^^ ^,ௗ^^^^^௧^^^ ^^^ ⋅ ^^^^^^^^^ = = ^ ^^^^ ^^^^ = ^,ௗ^^^^^௧^^^ ^^^ 7The carbon ఛ^^^Δ^^^,^^^ ^^^^^,ௗ ^^^ ⋅ ^^^^^^^^^ = 100 ⋅^^ = 100 ⋅ ^ ^^^^^௧^^^ ^^^^ ^^^^ = 100 ⋅ ^,ௗ^^^^^௧^^^ ^^^ 8^௧ୀ^ ^^^ ^^^ The reactor specific time is defined as follows: • Batch / Fixed bed: ^^^^^= total pyrolysis time • Moving bed: ^^^^^= mean residence time of carrier particles in the pyrolysis zone • Fluidized bed: ^^^^^= mean residence time of carrier particles in the pyrolysis zone Reference mass in [g]: • Batch / Fixed bed: ^^^= initial carrier mass in the reactor •Moving bed: ^^^ = ^^^^^^^^^^^^ ∙ ^^^^^ with the reactor inlet mass flow ^^^^^^^^^^^^ in [g / s]• Fluidized bed: ^^ = ^^^^^^^^ ^^^^ ^^^^ ∙ ^^^^^ with the reactor inlet mass flow ^^ ^^^^^^^ in [g / s]Depending on the available instrumentation and analysis methods, different ways for the practical application of the described theoretical framework for the calculation of ^^^^^^^exist. It is important to note that the specific material property must be measured before the pyrolysis (index “0”) and after a pyrolysis time of ^^^^^(index “1”). Exemplary ways of application: • Using the Sauter mean diameter of the particle size distribution and the measured real density from helium or xylene pycnometer:^^=6 ^^ଷ ^^^^ ௌ^௨௧^^,^ ⋅ ^^ ଷ^ ு^,^, ^^^ =6 ^^ௌ^௨௧^^,^ ⋅ ^^ு^,^ 9 •Using a mass ^௨^^,^,^^^ ^^^௨^^,^ ^^^௨^^,^^௨^^,^ =^^ , ^^^௨^^,^ =^^^ ^^^^^ 11 • Using the measured or calculated initial carrier weight ^^^, using gas analytics for the calculation of conver- sion rate, using the measured of calculated molar flow rates and applying the detailed formulas given above. Moving bed: The solid carbon mass from hydrocarbon pyrolysis deposited on one solid granule in one pass through the reactor divided by the mass of the said one solid granule before entering the reactor. The mass of the said solid particle before and after the pyrolysis is calculated by the Sauter mean diameter of the particle size distribution and the real density of the used granule. The reference residence time according to equations 7-8 is preferably between 0.1 and 15 h, preferably between 1 and 10 h and more preferably between 2 and 8 h. Fixed bed: The solid carbon mass from hydrocarbon pyrolysis deposed on one solid granule during its residence time in the reactor divided by the mass of the said one solid granule before entering the reactor. The mass of the said solid particle before and after the pyrolysis is calculated by the Sauter mean diameter of the particle size distribution and the real density of the used granule. The reference residence time according to equations 7-8 is preferably 0.1 to 90 h, more preferably 0.25 to 50 h, more preferably 0.5 to 25 h and even more preferably 1.0 to 10 h. Fluidized bed: The solid carbon mass from hydrocarbon pyrolysis deposited on one solid granule during one inner circulation through the reactor divided by the mass of the said one solid granule before entering the reactor. The mass of the said solid particle before and after the pyrolysis is calculated by the Sauter mean diameter of the particle size distribution and the real density of the used granule. In a fluidized bed, one particle can circulate multiple times through the reactor during its residence time inside the reactor. The reference residence time according to equations 7-8 is preferably 0.1 to 90 h, more preferably 0.25 to 50 h, more preferably 0.5 to 25 h and even more preferably 1.0 to 10 h. Measuring the Morphology: Details to the measuring is giving in the example section. The colour measurements of the L-parameter (perceptual lightness) is measured by photospectrometer. The e-module and hardness are measured by nanoindenter. The sur- face morphology is measured by SEM and the morphology is characterized by analyzing the SEM pictures. The me- dian pore diameter and pore volume are measured by HG porosimetry. Anisotropic pyrolytic carbonaceous material Preferably, the present invention relates to a pyrolytic carbon particle, which is obtained by a thermal decomposition of hydrocarbons, and said pyrolytic carbon particle has the following properties: - Carbon content 98 to 99.99 wt.-%, preferably 99 to 99.99 wt.-%, more preferably 99.5 to 99.99 wt.-% - Particle size from 0.1 to 10 mm, preferably 0.5 to 10 mm, more preferably 1 to 8 mm - Ash content 0 to 2 wt.-%, preferably 0 to 1 wt.-%, more preferably 0 to 0.5 wt.-% - Specific surface area 5 to 25 m2 / g, preferably 5 to 20 m2 / g, more preferably 10 to 20 m2 / g - Median pore diameter (volume) from 0.005 to 1 µm, and wherein said pyrolytic carbon particle comprises at least two layers of pyrolytic carbon having different carbon morphologies, wherein each morphology is defined by the following parameters: - e-module being in the range of 5 to 35 GPa and - hardness being in the range of 0.2 to 5 GPa, - L-parameter of colour from 10 to 45 and wherein at least one of the parameter of a first morphology of a first layer of pyrolytic carbon deviates from 20 to 300% of the respective parameter of a second morphology of a second layer of pyrolytic carbon, wherein the first layer and the second layer are adjacent to each other. Preferably at least two of said parameters e-module, hardness and / or L-Parameter, more preferably of all three pa- rameters, of a first morphology of a first layer of pyrolytic carbon deviates from 30 to 250% ,in relation to the absolute value, of the respective parameter of a second morphology of a second layer of pyrolytic carbon, wherein the first layer and the second layer are adjacent to each other. Preferably, the deviation is from 40 to 200 %, even more preferably 40 to 150 %, even more preferably 50 to 100 %, of the value of the adjacent layer. Preferably, the said pyrolytic carbon particles have at least two layers of pyrolytic carbon with different morphology, more preferably at least five layers, particularly at least 10 layers. Preferably the anisotropic pyrolytic carbon particles have 2 to 1000 layers of pyrolytic carbon with different morphology, more preferably 5 to 200 layers, particularly 10 to 100 layers. The thickness of the different layer is preferably 1 µm to 10 mm, more preferably 1 µm to 5 mm, even more prefera- bly 5 µm to 5 mm, even more preferably 10 µm to 2 mm, even more preferably 20 µm to 1 mm, even more prefera- bly 50 µm to 500 µm. Preferably, the second layer covers the outer surface of the first, underlying layer by at least by 80 % of the outer sur- face of the first layer; preferably by 85 %, even more preferably by 90 %, even more preferably by 95 %. Preferably, the first, underlying layer is completely covered / coated by the second layer. Preferably, said different layer alternate. Preferably, the first layer has a coral surface morphology and the second layer has a smooth morphology or the first layer has a smooth surface morphology and the second layer has a coral morphology. Preferably, the outer layer of said pyrolytic carbon particle has a coral surface morphology. Coral Morphology Preferably, the coral morphology is defined by: - E-Module from 5 to 25 GPa, preferably 5 to 20 GPa, more preferably 5 to 15 GPa, even more preferably 5 to 12 GPa - Hardness from 0.2 to 4 GPa, preferably 0.3 to 2 GPa, more preferably 0.4 to 1 - L-parameter of colour from 10 to 20, preferably 12 to 18, more preferably 13 to 17 - Coral surface morphology defined by SEM surface morphology method defined by the following descriptor parameters D1-D5 (definition of the descriptors are given in the Examples, 3.4): o D1, void size, from 65 to 110 nm o D2, total coral area, from 0.6 to 2.5 µm² o D3, void area, from 0.05 to 2.5 µm² o D4, light coral area, from 0.05 to 2.5 µm² o D5, coral shape, from 0.9 to 0.975. Preferably, this layer is additionally defined by - Carbon content 98 to 99.99 wt.-%, preferably 99 to 99.99 wt.-%, more preferably 99.5 to 99.99 wt.-% - Particle size from 0.1 to 10 mm, preferably 0.5 to 10 mm, more preferably 1 to 8 mm - Ash content 0 to 2 wt.-%, preferably 0 to 1 wt.-%, more preferably 0 to 0.5 wt.-% - Specific surface area 5 to 25 m2 / g, preferably 7 to 20 m2 / g, more preferably 10 to 20 m2 / g - Median pore diameter from 0.005 to 1 µm, preferably 0.05 to 1 µm Preferably, the coral morphology is obtained by the following process conditions: at a pressure of 2.5 to 25 bara (bar absolute) and a temperature of 1000 to 1450°C and a hydrocarbon concentration in the feed of 10 to 50 vol.-%; more preferably at a pressure of 5 to 20 bara (bar absolute) and a temperature of 1100 to 1450°C and a hydrocarbon con- centration in the feed of 10 to 45 vol.-%; even more preferably at a pressure of 8 to 20 bara (bar absolute) and a tem- perature of 1200 to 1400°C and a hydrocarbon concentration in the feed of 10 to 40 vol.-%. The conversion rate is preferably 25 to 85 %, more preferably 30 to 80 %, even more preferably 50 to 80 % (based on the hydrocarbons in the feed stream). The carbon deposition rate of solid pyrolytic carbon is preferably 0.1 to 15 wt.-%, more preferably 2 to 12 wt.-%, even more preferably 3 to 10 wt.-%, even more preferably 4 to 8 wt.-%. The layer of the coral surface morphology covers preferably at least 80 % of the underlying surface / layer, preferably 85 %, more preferably 905, even more preferably 95, even more preferably 985. Most preferred, the layer of the coral surface morphology covers the underlying surface / layer of the particle completely. Smooth morphology Preferably, the smooth morphology is defined by: - E-Module from 5 to 35 GPa, preferably 5 to 25 GPa, more preferably 10 to 20 GPa, even more preferably 8 to 20 GPa - Hardness from 0.7 to 5 GPa, preferably 1 to 4 GPa, more preferably 1.2 to 3 GPa, even more preferably 1.2 to 2.5 - L-parameter of colour from 25 to 45, preferably 30 to 45 GPa, more preferably 35 to 45, even more prefera- bly 38 to 42 - Smooth surface morphology defined by SEM surface morphology method defined by the following de- scriptor parameter D3: o D3, void area, from 0 to 0.049 µm² Preferably, this layer is additionally defined by - Carbon content 98 to 99.99 wt.-%, preferably 99 to 99.99 wt.-%, more preferably 99.5 to 99.99 wt.-% - Particle size from 0.1 to 10 mm, preferably 0.5 to 10 mm, more preferably 1 to 8 mm - Ash content 0 to 2 wt.-%, preferably 0 to 1 wt.-%, more preferably 0 to 0.5 wt.-% - Specific surface area 5 to 20 m2 / g, preferably 7 to 15 m2 / g, more preferably 8 to 12 m2 / g - Median pore diameter from 0.005 to 0.1 µm, Preferably, the smooth morphology is obtained by the following process conditions: at a pressure of 0.7 to 1.5 bara (bar absolute) and a temperature of 1350 to 1500°C and a hydrocarbon concentration in the feed of 10 to 80 vol.-%; more preferably at a pressure of 1 to 1.2 bara (bar absolute) and a temperature of 1400 to 1500°C and a hydrocar- bon concentration in the feed of 10 to 50 vol.-%. The conversion rate is preferably 25 to 85 %, more preferably 30 to 80 %, even more preferably 50 to 80 % (based on the hydrocarbons in the feed stream). The carbon deposition rate of solid pyrolytic carbon is preferably 0.1 to 15 wt.-%, more preferably 2 to 12 wt.-%, even more preferably 3 to 10 wt.-%, even more preferably 4 to 8 wt.-%. The layer of the smooth surface morphology covers preferably at least 80 % of the underlying surface / layer, prefera- bly 85 %, more preferably 905, even more preferably 95, even more preferably 985. Most preferred, the layer of the smooth surface morphology covers the underlying surface / layer of the particle completely. Core of said pyrolytic carbon particle The bed material used in said fixed, fluidized or moving bed is preferably initially the core of said pyrolytic carbon par- ticle. As the pyrolysis of hydrocarbon is preferably conducted continuously, the obtained pyrolytic carbon particles are preferably at least partly recycled, optionally grinded and introduced into the reactor, so that cycle by cycle, the initial core will be replaced by pyrolytic carbon itself. Process of producing anisotropic pyrolytic carbon In addition, the present invention comprises a process of producing said anisotropic pyrolytic carbon particles which comprise at least two layers of pyrolytic carbon having different carbon morphology by decomposition of hydrocar- bons in a fixed, fluidized or moving bed at a pressure of 1 to 30 bar and a temperature of 800 to 1500°C and a hydro- carbon concentration in the feed of 2.5 to 100 vol.-%, wherein the decomposition is conducted stepwise with at least two different, optionally alternating, process conditions; wherein one of the at least two process conditions differ in at least one of the following process parameters to the other process condition: at least 20 °C difference in temperature and / or at least 100 mbar difference in pressure and / or at least 5 vol.-% difference in hydrocarbon concentration and wherein the at least one process condition is kept until a thickness of the pyrolytic layer of said carbon morphol- ogy of 1 µm to 10 mm. Preferably, the following process conditions are used: - temperature from 1000 to 1500, more preferably from 1200 to 1400 - hydrocarbon concentration in the feed of 5 – 90 vol.-%, more preferably 10- 80 vol.-%, even more preferably from 15 to 60 vol.-% Typical process fluctuations are below the named range of the needed difference between the at least two different process conditions. Preferably, the one process condition differs to the other process condition in temperature by at least a difference of 50°C, more preferably by at least difference of 100°C. Preferably, the one process condition differs to the other process condition in pressure by at least a difference of 200 mbar, more preferably by at least difference of 500 mbar, even more preferably by at least difference of 1 bar. Preferably, the one process condition differs to the other process condition in hydrocarbon concentration in the feed by at least a difference of 10 vol.-% in the hydrocarbon concentration, more preferably by at least difference of 20 vol.-%, even more preferably by at least difference of 30 vol.-%. Preferably, said one process condition is kept until the needed thickness of the said of preferably 1 µm to 15 mm is reached, more preferably 5 µm to 10 mm, even more preferably 10 µm to 8 mm, even more preferably 50 µm to 5 mm, even more preferably 100 µm to 2 mm, even more preferably 100 µm to 1 mm, is reached. Preferably the duration of said one process condition is in the range of 10 min to 30 day, more preferably in the range of 20 min to 10 hours, even more preferably in the range of 30 min to 5 hours. If a moving bed is used, the duration of said different process conditions is preferably at least one passage of the solid material (moving bed) through the reactor (residence time), more preferably at least two passages through the reaction. Preferably one to ten passages of the moving bed through the reactor, more preferably one to five pas- sages, even more preferably two to four passages. General pyrolysis process of hydrocarbons The process of pyrolyzing hydrocarbons to produce hydrogen and solid carbon is well described in the state of the art. Typical hydrocarbon feedstocks for pyrolysis processes are gaseous hydrocarbons, like natural gas, methane, ethane, biogas, like biomethane. Typically, natural gas contains hydrocarbons with a ratio of C1 / C2+ of 3 to 100, more preferably 3 to 50, even more preferably 3 to 25, even more preferably 4 to 20, even more preferably 5 to 15. The conversion rate is preferably 25 to 85 %, more preferably 30 to 80 %, even more preferably 50 to 80 % (based on the hydrocarbons in the feed stream). The carbon deposition rate of solid pyrolytic carbon is preferably 0.1 to 15 wt.-%, more preferably 2 to 12 wt.-%, even more preferably 3 to 10 wt.-%, even more preferably 4 to 8 wt.-%. The methane pyrolysis process can be heated in different ways known to the persons skilled in the art: heated carrier gas, resistance heating, induction or autothermal. Preferably the methane pyrolysis process is heated electrically, even more preferably by resistive heating (Joule heating) of the solid material as described for example in US 2982622, WO 2019 / 145279 and WO 2020 / 200522. The methane pyrolysis results in a hydrogen-containing product stream and solid carbon. Depending on the reaction conditions, the content of the hydrogen-containing product stream - related to the total volume of the hydrogen-containing product stream - is preferably: (i) hydrogen preferably between 30 vol% and 99 vol%, more preferably between 50 vol% and 98 vol%, and in partic- ular between 60 vol% and 98 vol%, (ii) methane preferably between 1 and 60 vol%, more preferably between 2 and 40 vol% and in particular between 2 and 30 vol%, (iii) the sum of the contents of all C2+ hydrocarbon components comprising e.g. C2H6, C2H4, C2H2, C3H8, C3H6, C3H4, C4H8, C4H6, C6H6, C7H8, C8H10 preferably between 0 and 1 mol%, more preferably between 0 and 0.5 mol% and in particular between 0 and 0.1mol%, (iv) nitrogen preferably between 0 and 20vol%, more preferably between 0 and 10vol% and in particular between 0 and 5 vol%, carbon monoxide preferably between 0 and 2vol%, more preferably between 0 and 1vol% and in par- ticular between 0 and 0.5 vol%, carbon dioxide preferably between 0 and 2vol%, more preferably between 0 and 1vol% and in particular between 0 and 0.5 vol% and the water preferably between 0 and 2vol%, more preferably between 0 and 1vol% and in particular between 0 and 0.5 vol%. The hydrogen-containing stream preferably contains hydrocarbons with a ratio of C1 / C2+ of 4 to 10000, more prefer- ably 15 to 1000, even more preferably 20 to 500, even more preferably 30 to 250, even more preferably 50 to 200. H2 / C1+ ratio The hydrocarbon concentration in the feed is preferably below 100 vol.-%. Preferably, the respective H2 / C1+ ratio of the total reactor feed stream ranges from 0.5 to 25, more preferably from 0.75 to 10, even more preferably from 1 to 8, even more preferably 2 to 6. Typically, the total reactor feed stream contains preferred 50 to 95 Vol.-% hydrogen, more preferred 65 to 85 Vol% hydrogen, 5 to 50 Vol.-% hydrocarbons, more preferred 35 to 15 vol% hydrocarbons, and 0 to 3 Vol.-% inert gases, particularly nitrogen and argon. The total reactor feed stream preferably contains hydrocarbons with a ratio of C1 / C2+ of 15 to 500, more preferably 17 to 100, even more preferably 20 to 50. There are several process layouts how to realize said H2 / C1+, particularly H2 / CH4 feed molar ratio. Without exclud- ing further options, preferred layouts are: - Direct gas recycle: a portion of the reactor effluent gas stream is recycled without any purification steps. Gas streams may or may not be cooled or heated. - Recycle after purification unit: The hydrogen depleted gas stream after any purification or gas separation unit is recycled to the reactor, while a fraction is purged. - Gas streams employed for pneumatic transport of solids are recycled to the reactor. - Hydrogen containing gas streams from different processes or other sources are mixed to the hydrogen feed stream. Preferably, an internal recycle of the hydrogen-containing product stream is used to control the H2 / C1+ molar ratio, that means, a portion of the raw hydrogen-containing product stream is recycled without any purification steps. Said recycled hydrogen-containing product stream may or may not be cooled, heated and / or compressed. The hydrogen-containing product stream leaving the reaction chamber preferably enters a separation unit. This sepa- ration unit typically includes a valve, a flow meter, and a meter to determine the H2 concentration. Preferably, 20 vol% to 90 vol% of the hydrogen-containing product stream is separated and recycled to the reaction chamber, more preferably 30 vol % to 85 vol %, more preferably 40 vol % to 85 vol %, even more preferably 50 vol % to 80 vol %. The vol% of the hydrogen-containing product stream taken for the internal direct recycle is preferably adjusted to a molar ratio H2 / C1+ of the total reactor feed stream ranging from 0.1 to 25, more preferably from 0.5 to 10, even more preferably from 1 to 8. The recycled hydrogen-containing product stream is mixed with the external feed stream, e.g. natural gas, inside or outside the reaction chamber. Before mixing, the temperature of the internally recycled hydrogen-containing product stream is preferably between 10°C and 200°C, even more preferably between 15 and 150°C and in particular be- tween 20 and 100°C. Preferably, the external feed stream and the recycled hydrogen-containing product stream are mixed before entering the rection chamber, outside of the reactor. Alternatively, the streams are separately intro- duced into the reaction chamber. Therefore, the feed of the pyrolysis process contains at least two feed streams: (i) external feed stream containing hydrocarbons, preferably gaseous and liquid hydrocarbons, more preferably gaseous hydrocarbons, even more pref- erably methane and / or other light hydrocarbons feed stream, preferably natural gas and (ii) an internally recycled hy- drogen-containing product stream. Preferred Operation Mode Preferably, said process for producing pyrolytic carbon particle which comprises at least two layers of pyrolytic car- bon having different carbon morphology is conducted in a plant comprising at least two reactors, wherein in all reac- tors a decomposition of hydrocarbons in a fixed, fluidized or moving bed is conducted, wherein the process condi- tions of the decomposition differ from reactor to reactor, but are fixed per reactor, and wherein at least part of the py- rolytic carbon formed in one of the reactors is passed to another reactor and used as bed material in said other reac- tor and the process conditions of the at least one reactor differ in at least one of the following process parameters to the other reactor: at least 20 °C difference in temperature and / or at least 100 mbar difference in pressure and / or at least 5 vol.-% difference in hydrocarbon concentration and wherein solid carbon is kept in said reactor until a thickness of the pyrolytic layer of said carbon morphology of 1 µm to 10 mm is reached. Preferably, at least part of the pyrolytic carbon formed in a first reactor is passed to another reactor and used as bed material in a second reactor and after a thickness of the pyrolytic layer of said carbon morphology of 1 µm to 10 mm is reached in said second reactor, at least part of the pyrolytic carbon formed in said second reactor is passed back to said first reactor and used as bed material in said first reactor. Pretreatment or temporarily treatment Preferably, before the process step of pyrolyzing of hydrocarbons the bed material is pretreated, even more prefera- bly if the oxygen and ash content higher than 1 wt.-%. For this pre- or temporarily treatment preferably an atmosphere of hydrogen and / or inert gases is used. Preferably the atmosphere contains 70 to 100 Vol.-%, related to the total atmosphere used for the treatment, of hydrogen and / or inert gases like nitrogen, argon, helium; more preferably 80 to 100 Vol.-% of hydrogen and / or inert gases, more pref- erably 90 to 100 Vol.-%, even more preferably 95 to 100 Vol.-%. The atmosphere contains 30 to 0 Vol.-% of gaseous hydrocarbons, preferably 20 to 0 Vol.-%, more preferably 10 to 0 Vol.-%, more preferably 5 to 0 Vol.-%, even more preferably 2 to 0 Vol.-%, the methane content in said gaseous hydrocarbons is preferably 85 to 100 Vol.-%, more preferably 90 to 100 Vol.-%, even more preferably 95 to 100 Vol.-%, in particular 99 to 100 Vol.-%. The time and temperature of said treatment is characterized by the formula T = time (min) multiplied by temperature (°C) and the T is at least 10000 (min °C) and wherein the temperature is at least 500°C. Preferably T is at least 20000 (min °C), more preferably T is at least 50000 (min °C), even more preferably T is at least 100000 (min °C). Preferably T is in the range of 3000 to 1500000 (min °C), more preferably in the range of 10000 to 900000 (min °C) ), more preferably in the range of 50000 to 700000 (min °C),even more preferably in the range of 100000 to 300000 (min °C) Preferably the temperature of said treatment is at least 600°C, more preferably at least 700°C, more preferably at least 800°C, more preferably at least 900°C, even more preferably at least 1000°C. Preferably the temperature of said treatment is in the range of 500°C to 2500°C, more preferably in the range of 600°C to 2000°C, more preferably in the range of 1000°C to 1500°C, even more preferably in the range of 1200°C to 1400°C. The time of said treatment is at least 5 min, more preferably at least 30 min, more preferably at least 60 min, more preferably at least 90 min, more preferably at least 120 min, even more preferably at least 180 min. Preferably the time / period of said treatment is in the range of 5 min to 10 days, preferably 5 min to 5 days, more pref- erably 5 min to 3 days, more preferably 5 min to 1 day, more preferably in the range of 10 min to 12 hours, even more preferably in the range of 30 min to 720 min. If a moving bed is using, the time / period of said treatment is pref- erably at least one passage of the solid material (moving bed) through the reactor (residence time), more preferably at least two passages through the reaction. Preferably one to ten passages of the moving bed through the reactor, more preferably one to five passages, even more preferably one to four passages, even more preferably two to four passages, even more preferably one to two passages. The operating time in pre-treatment mode preferably exceeds the treatment time required for a single particle. This is due to two main factors: first, a transition period is necessary to switch between production mode and pre-treatment mode, allowing for the adjustment of operating conditions and stabilization of the system to the desired target state. Second, pre-treatment is performed on a larger quantity of material to ensure sufficient supply for the intended runtime of the subsequent production cycle. Alternatively, the pre-treatment can be controlled until the carrier material meets specific criteria. For example, the composition of the outflowing gas stream can be measured, preferably using FTIR according to DIN EN 15483:2009- 02. Key components of interest include carbon monoxide, carbon dioxide, water vapor, and hydrogen sulfide. Pre- treatment continues until the concentration of these components drops below a specified threshold. The cumulative mole fraction of H2O, CO, CO2, H2S, CS2, and COS should be less than 1 vol.-%, preferably less than 0,5 vol.-%, and particularly less than 0,1 vol.-%, especially less than 0.05 vol.-%. Additionally, the surface concentration of metallic elements on the carrier and / or the loading of the carrier with pyroly- sis carbon serves as a measure of pre-treatment effectiveness. The surface concentration, defined as the mass of metal impurities relative to the outer surface of the carrier particles, should be determined semi-quantitatively by SEM / EDX according to ASTM F1375-92(2020). The acceptable surface concentration of metallic impurities should be less than 0.1 mg / cm² to 1 mg / cm². During said treatment, the carbon deposition rate of the pyrolysis process, if any, is preferably below 5 wt.-%, more preferably below 2 wt.-%, even more preferably below 1 wt.-%. Preferably, the deposition rate during said treatment is in the range of 0 to 5 wt.-%, more preferably 0 to 2 wt.-%, even more preferably 0 to 1 wt.-%. During said treatment, the conversion rate of the pyrolysis process, if any, is preferably below 75 %, more preferably below 50 %, even more preferably below 30 %, even more preferably below 20 % (based on the hydrocarbons in the feed stream). Preferably, the conversion rate during said treatment is in the range of 0 to 75 %, more preferably 0 to 50 %, even more preferably 0 to 30 %, even more preferably 0 to 20 %. During said treatment, the hydrocarbons if any contained in the treatment atmosphere have a volume ratio of C1 / C2+ of 15 to 500, more preferably 17 to 100, even more preferably 20 to 50. Adaption of the process parameters and pretreatment The concrete preferred process conditions are depending on the bed material used. In principle, a person skilled in the art preferably adapts the process conditions of the pretreatment and the hydrocarbon pyrolysis as follows: 1. Making an elemental analysis of the bed material. 2: Adjusting the pretreatment to the chemical composition: the higher the oxygen and ash content of the bed material the lower the deposition rate during the first operation time. If oxygen and / or ash content is higher than 1 wt.-%, pre- treatment is preferred. Said pretreatment can preferably end, if no or a non-significant content of oxygen containing side product, like water CO, CO2 are present, e.g. water below 0.01 vol.-% and CO below 250 ppm, in the hydrogen containing product stream, then the pyrolysis process can preferably be started. 3. Adjusting the process conditions of the pyrolysis conditions, especially the deposition rate, preferably start with a low deposition rate like 1 wt.-% deposition and slowly increasing the deposition rates as the operation time increases, e.g. increase of 1 wt.-% in deposition rate after 10 min to 1 hour of operation time or increase of 1 wt.-% in deposition rate per passage of the bed material through a moving bed reactor. Preferred Process Conditions: Moving Bed Preferably the solid material (also called substrate) is guided in form of a moving bed through the reaction chamber, with methane and / or other light hydrocarbons being passed advantageously in countercurrent to the substrate. For this purpose, the reaction chamber is preferably designed as a vertical reactor, which means that the movement of the moving bed is gravity driven. Flow through the moving bed is taking place, advantageously, homogeneously, and uniformly (see for example WO 2013 / 004398, WO 2019 / 145279 and WO 2020 / 200522). Methane and / or other light hydrocarbons are preferably introduced via the bottom of the reactor, preferably having a temperature of 10 to 200°C. The substrate is preferably introduced via the top of the reactor, preferably having a temperature of 10 to 200°C. The hydrogen-containing product gas is preferably taken off via the top of the reactor, preferably having a temperature of 10 to 200°C. The granular pyrolytic carbon is preferably taken off via the bottom of the reactor, prefer- ably having a temperature of 10 to 200°C. The discharged carbon is preferably at least partly recycled and introduced into the reactor again using it as sub- strate for the moving bed. As a result, a continuous process of the moving bed is achieved. The recycled carbon can optionally be mixed with fresh, initial solid material. The flow velocity of the substrate is advantageously in the range of 0.005 to 6.0 cm / s, more preferably 0.005 to 0.5 cm / s. The flow velocity of the gas flow is advantageously in the range of 0.025 to 10 m / s, more preferably 0.025 to 2 m / s. The gas residence time in the reactor is advantageously between 0.1 and 50 s, preferably between 1 and 20 s. The residence time of the substrate is preferably between 0.1 and 15 hours, preferably between 1 and 10 hours and more preferably between 2 and 8 hours. Solid material The solid material, also called substrate or carrier material, is preferably a granular material. The particle size of a preferred substrate is in the range of 0.1 to 10 mm, preferably 0.3 to 8 mm. The preferred substrate is a carbon-containing substrate, for example calcined petcoke (CPC), green coke, anode butts, bio char, recycled carbon black (from polymer recycling via pyrolysis), black mass (battery recycling) or the pyrolytic carbon itself. The carbon content is preferably in the range of 70 to 99 wt.%, more preferably 90 wt.% to 99.9 wt.%, more preferably 99 to 99.95 wt.%, even more preferably 99 to 99.99 wt.%. The oxygen content is preferably in the range of 20 to 0.001 wt.%, more preferably 5 wt.% to 0.1 wt.%, more prefera- bly 1 wt % to 0.5 wt%. The ash content, in particular Fe, Ni, Ca, Si, Al, Cr, K, Mg, Mn, Pb, V and Zn, is preferably in the range 20 to 0.001 wt.%, more preferably 5 wt.% to 0.1 wt.%, more preferably 1 wt % to 0.5 wt%. The Sulphur content is preferably in the range 5 to 0.0001 wt.%, more preferably 0.5 wt.% to 0.01 wt.%, more prefer- ably 0.1 wt % to 0.01 wt%. The chlorine content is preferably in the range 1 to 0.00001 wt.%, more preferably 0.1 wt % to 0.001 wt%, even more preferably 0.01 wt.% to 0.1 wt.%. Preferably, the metal-content on the outer surface (defined by the outer shell of 5 µm thickness), is preferably in the range 20 to 0.001 wt.%, more preferably 5 wt.% to 0.001 wt.%, more preferably 1 wt % to 0.001 wt%, even more preferably 0.5 wt.% to 0.001 wt.%. The BET surface area of the substrate is preferably between 0.1 and 100 m2 / g, preferably 0.1 and 50 m2 / g, in partic- ular 0.1 to 30 m2 / g. Preferably, the density of the substrate is in the range of 1.5 to 2.5 g / cc (real density in xylene, ISO 8004). Preferably, the bulk density of the substrate is in the range of 0.5 to 1.5 g / cc. Pyrolytic granular carbon Typically, the density of the deposited pyrolytic carbon produced via the described methane pyrolysis process is in the range of 1.5 to 2.5 g / cc, preferably 2.0 to 2.3 g / cc (real density in xylene, ISO 8004). Typically, the bulk density of the pyrolytic carbon is in the range of 0.5 to 1.5 g / cc, more preferably 0.7 to 1.3 g / cc. Typically, the ash content of the pyrolytic carbon is in the range of 0.001 to 1 weight-%, preferably 0.01 to 0.2 weight- %. Typically, the carbon content is in the range of 98 to 100 weight-%, more preferably 99.5 to 100 weight-%, even more 99.75 to 100 weight-%, even more 99.9 to 100 weight-%. Typically, the porosity of the granular pyrolytic carbon is between 0% to 15%, preferably 0.2% to 10%, most prefera- bly 0.2% to 5% (Hg porosimetry, DIN66133). Typically, the specific surface area of the pyrolytic carbon measured by Hg porosimetry (DIN66133) is in the range of 0.001 to 20 m2 / g, preferably 0.001 to 10 m2 / g, even more preferably 0.05 to 5 m2 / g. Preferred Moving Bed Method Preferably a moving bed technology is used for the methane pyrolysis of the present invention comprising: - a plurality of solid substrates is guided into the first heat integration zone and from there into the reaction zone, - the solid substrates are heated in the reaction zone, - the solid substrates are guided from the reaction zone into the second heat integration zone and are with- drawn from the second heat integration zone, - methane is introduced into the second heat integration zone and from there into the reaction zone, wherein methane in the second heat integration zone is heated against solid substrates coming from the reaction zone, wherein the solid substrates are cooled, and wherein the methane is contacted with the heated solid substrates in the reaction zone, wherein heat from the heated solid substrates is transferred to methane in order to heat methane in the reaction zone, wherein methane is decomposed to hydrogen and granular pyro- lytic carbon in the reaction zone, - hydrogen produced is guided from the reaction zone into the first heat integration zone, wherein the solid sub- strates in the first heat integration zone are preheated against hydrogen coming from the reaction zone, wherein hydrogen is cooled, and wherein - hydrogen is withdrawn from the first heat integration zone - granular pyrolytic carbon produced is deposited on solid substrates and withdrawn with the substrates - withdrawn substrate is preferably at least partly recycled and introduced into the reactor - withdrawn hydrogen is preferably at least partly recycled and introduced into the reactor. Preferred Reactor Preferably, the reactor for carrying out the methane pyrolysis, in which hydrogen and pyrolytic carbon are produced from hydrocarbons, preferably methane, comprises: - a reactor surrounding a reactor interior - the reactor is configured to provide a gravity-driven moving bed in a reaction zone of the reactor interior, which gravity-driven moving bed comprises a large number plurality of solid substrates, wherein the reactor is also configured to guide methane into the reaction zone, wherein, in order to heat methane, the reactor is configured to heat the solid substrates in the reaction zone by generating an electric current in the solid sub- strates between a pair of first and second electrodes such that, by transferring heat from the solid sub- strates to methane, - methane in the reaction zone can be heated to a reaction temperature to produce hydrogen and granular pyrolytic carbon, - and wherein the reactor interior also comprises a first heat integration zone in which heat from hydrogen produced in the reaction zone can be transferred to solid substrates of the reactor gravity driven moving bed which are to be guided into the reaction zone, and wherein the reactor interior also comprises a second heat integration zone in which heat from solid substrates of the reactor gravity driven moving bed coming from the reaction zone can be transferred to methane in order to preheat methane, wherein said reaction zone is arranged between said pair of first and second electrodes and said first heat integration zone is arranged above said first electrode and said second heat integration zone is arranged below said second electrode. The volume of the reaction section is preferably 1 m3 to 1000 m3, preferably 5 m3 to 750 m3, more preferably 0.5 m3 to 500 m3. The height of the reaction section is preferably 0.1 m to 50 m, preferably 0.5 to 20 m, more preferably 1 m to 10 m. The said moving bed reactor has several advantageous compared to other reactor types. - Heat integration enables a high efficiency since gas and solid are leaving the reactor at temperatures be- tween 10 °C – 200 °C - No additional equipment for heat recovery or special equipment for handling of gas solids with temperatures above 200 °C required. - Reproduceable carbon quality: Each particle is treated under the same conditions in the moving bed. Same residence time for each solid particle in the reaction zone. Preferred Fixed Bed Method Preferably a fixed bed technology is used for the methane pyrolysis of the present invention comprising: - a plurality of solid substrates having a particle size of 0.5 to 10 mm is introduced into the reactor and fixed in the reaction zone, preferably the substrates are introduced via the top of the reactor, - the solid substrates are heated in the reaction zone, preferably the solids are electrically heated, more prefer- ably the solids are heated via a direct electric Joule heating, - methane is introduced into the reaction zone, wherein the methane is contacted with the heated solid sub- strates in the reaction zone, wherein heat from the heated solid substrates is transferred to methane in order to heat methane in the reaction zone and wherein methane is decomposed to hydrogen and pyrolytic carbon that is deposited on the solid substrates in the reaction zone, preferably methane is introduced via the top of the reactor, - hydrogen is withdrawn from the reaction zone, preferably from the bottom of the reactor - By feeding hydrocarbon from the top into the reactor, the gas velocity is not limited by the fluidization regime of the solid particles, which allows higher space time yields compared to moving bed or fluidized bed reactors. Gas velocities in the reaction zone (calculated for an empty reactor) are 0,5 – 15 m / s and more preferred 1 – 10 m / s. In addition, the residence time of the substrate can be increased to 2 to 24 hours. - batchwise the solid substrates with pyrolytic carbon deposited on it are withdrawn from the reaction zone - withdrawn substrate is preferably at least partly recycled and introduced into the reactor - withdrawn hydrogen is preferably at least partly recycled and introduced into the reactor. Fixed bed reactors are known in the state of the art, e.g. [1] Eigenberger, Ruppel, Ullmanns’s encyclopedia of indus- trial chemistry Catalytic Fixed-Bed Reactors, 2012 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim. Typically, several fixed bed reactors are combined in a cyclic mode operation e.g. One reactor is in production mode and carbon is deposed in the fixed bed until the maximum carbon deposition is reached. While the carbon is re- moved from this reactor, the next reactor starts with production and so on. With this cyclic operation mode, a continu- ous production is ensured. Preferred Fluidized Bed Method Preferably a fluidized bed technology is used for the methane pyrolysis of the present invention comprising: - a plurality of solid substrates having a particle size of 0.1 to 10 mm is introduced in the fluidization zone, the reaction zone, and placed on a distributor o optionally the substrates are heated externally and are introduced into the reactor at a temperature of 800 °C to 1500 °C - optionally the solid substrates are heated in the reaction zone, preferably the solids are electrically heated, - methane is introduced into the reactor via the bottom, distributed by the distributor fluidizing the solid sub- strates and guided through the reaction zone wherein methane is contacted with the heated solid substrates in the reaction zone, wherein heat from the heated solid substrates is transferred to methane in order to heat methane in the reaction zone, wherein methane is decomposed to hydrogen and pyrolytic carbon that is de- posited on the solid substrates in the reaction zone, o The Hydrocarbon concentration of the feed gas ranges preferably from 20 vol% - 100 vol %, more prefera- bly form 60 vol% to 100 vol % o Due to the relative motion of the particles in a fluidized, carbon deposition rates from the pyrolyzed gas on the solid granule per pass through the reactor are preferred above 10 w% and more preferred above 20 w%. The relative deposition is related to the mean solid particle mass flux out of the reactor. o The pressure is preferably 1 to 10 bar. - hydrogen is withdrawn from the reaction zone, preferably from the top of the reactor - preferably continuously, the solid substrates with pyrolytic carbon deposited on it are withdrawn from the reac- tion zone - withdrawn substrate is preferably at least partly recycled and introduced into the reactor - withdrawn hydrogen is preferably at least partly recycled and introduced into the reactor. Fluidized bed reactors are known in the state of the art, e.g[2]. Werther, Ullmanns’s encyclopedia of industrial chem- istry Fluidized Bed-Reactors, 2012 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim. A fluidized bed reactor may have more than one stage as described in WO2022081170 and US20210331918. H2 Purification The part of the hydrogen-containing product stream that is not internally recycled into the reaction chamber is typi- cally purified in a removal apparatus, e.g. using adsorption or membrane technologies. For example, the gaseous product stream can still contain hydrogen sulfide. Hydrogen sulfide can preferably be re- moved from the gaseous product stream via gas scrubbing, e.g. via ZnO, CuZnO, Fe(OH)3, Zeolites, MOFs, as known in the state of the art. Typical process conditions of the gas scrubbing are 60 to 180°C and 1 to 100 bar. For example, the gaseous product stream can still contain carbon oxide and inert gases, e.g. nitrogen. Correspond- ing hydrogen recovery apparatuses are common knowledge to the person skilled in the art, for example pressure swing adsorption or permeation. Recycle of purification off-gas Preferably, a part of the off-gas from the hydrogen recovery is additionally internally recycled to the reaction cham- ber, preferably 5 to 100 vol.-% of the total off-gas, more preferably 10 to 98 vol.-%, even more preferably 25 to 95 vol.-%, even more preferably 50 to 95 vol.-% even more preferably 70 to 95 vol.-% even more preferably 80 to 95 vol.-%. Preferably, the remaining part of said total off-gas from the hydrogen recovery is withdrawn. The preferred percentage of recycle and withdrawal is dependent on the amount of inert gases in the hydrogen-containing product stream, especially on the nitrogen content. Composition of anisotropic pyrolytic carbon The present invention also relates to a composition comprising a mixture of anisotropic pyrolytic carbon and a binder. All binders known in the literature can be used (Perruchoud, Raymond C., Markus W. Meier, and Werner K. Fischer. "Survey on worldwide prebaked anode quality." LIGHT METALS-WARRENDALE-PROCEEDINGS-. TMS, 2004). Preferably, coal tar pitch binder or a combination of pitch binder can be used as a binder. The interplay of binder consumption and adhesive strength of the agglomerates can be adjusted, especially, also by combining multiple carbon species with different morphologies in an electrode recipe. The present invention also comprises a blend composition comprising a mixture of (i) petroleum coke and / or biochar in a content of 1 to 80 wt.-%, preferably 5 to 50 wt.-%, more preferably 10 to 30 wt.-% and (ii) anisotropic pyrolytic carbon according to the present invention in a content of 20 to 99 wt.-%, preferably 50 to 95 wt.-%, more preferably 30 to 70 wt.-% in view of the total weight of the blend composition. The present invention also comprises an electrode recipe comprising a mixture of (i) a blend composition of (ia) pe- troleum coke and / or bio char and (ib) anisotropic pyrolytic carbon according to the present invention, (ii) butts and / or scrap and (iii) binder material. Applications for blend composition or pyrolytic carbon as substitute for CPC and Advantages of the present invention 1. Enhanced thermal conductivity: Anisotropic carbon exhibits higher thermal conductivity compared to isotropic car- bon. This property makes it more efficient in conducting heat, making it suitable for applications that require heat dis- sipation or thermal management. 2. Improved mechanical strength: Anisotropic carbon possesses increased mechanical strength compared to iso- tropic carbon. This higher strength allows it to withstand higher loads and stresses, making it suitable for applications that require structural integrity and durability. 3. Directional electrical conductivity: Anisotropic carbon has directionally dependent electrical conductivity, meaning it conducts electricity more effectively in specific directions. This property can be advantageous in applications that re- quire precise control of electrical conductivity, such as in electronic components or conductive materials. 4. Tailored anisotropy: The anisotropy of carbon can be tailored to meet specific requirements by controlling the alignment or orientation of the carbon structure during the manufacturing process. This ability to customize anisot- ropy allows for the production of carbon materials with desired properties for specific applications. 5. Improved thermal expansion control: Anisotropic carbon offers better control over thermal expansion compared to isotropic carbon. This property is beneficial in applications where dimensional stability is crucial, such as in aero- space structures or high-precision equipment. 6. Enhanced electrical anisotropy: Anisotropic carbon exhibits directionally dependent electrical properties, such as electrical resistivity or dielectric constant. This property enables the design of materials with specific electrical behav- ior, making them suitable for applications such as electronic devices, sensors, or electromagnetic shielding. 7. Better orientation control: Anisotropic carbon allows for better control over the orientation of its crystal structure, resulting in improved alignment of its properties along specific directions. This controlled orientation can lead to opti- mized performance in applications that require anisotropic behavior, such as in composites or reinforcing materials. 8. Increased anisotropic physical properties: Anisotropic carbon can offer improved anisotropic physical properties, including strength, stiffness, hardness, or wear resistance, compared to isotropic carbon. These enhanced properties make anisotropic carbon suitable for demanding applications that require specific material characteristics. 9. Enhanced resistance to cracking or delamination: Anisotropic carbon exhibits improved resistance to cracking or delamination due to its aligned structure. This property can be advantageous in applications where material integrity and resistance to damage are critical, such as in structural components or composite materials. Description of the Figures Figure 1 presents a first pyrolytic carbon particle with layers of different morphology and the respective e-module and hardness measurements (a-c) and second pyrolytic carbon particle with layers of different morphology shown by dif- ferent lightness based on a photograph of the particle cross-section (d) Figure 2 presents the surface morphology of the respective different layers of the first pyrolytic carbon Figure 3 presents a second pyrolytic carbon particle with layers of different morphology and the respective e-module and hardness measurements Figure 4 presents a third pyrolytic particle with one layer on the core Figure 5 presents the internal recycle of the hydrogen containing product stream

[0002] Example: 1. State of the art Publication Process conditions Alternating process conditions WO 2020 / 016186 fluidized bed at tempera- no (PF180695) tures from 1100-1300 °C and at pressures from 1-2 bar(abs) fixed bed reactor at 1200 °C no at 1.0-1.2 bar(abs) WO 2021 / 122503 fluidized bed at tempera- no (PF191676) tures from 1100-1300 °C and at pressures from 1-2 bar(abs). WO 2023 / 57242 fixed-bed reactor that was no (PF161257) heated externally to 1450°C and volume flow of methane of 60 Nl / h (Example 1) and 1200°C and volume flow of methane of 120 Nl / h (Exam- ple 3) In WO 2020 / 016186 pyrolytic carbon was produced by decomposition of natural gas and deposition on petroleum coke as carrier material having a particle size of 0.5-2.5 mm in a fluidized bed at temperatures from 1100-1300 °C and at pressures from 1-2 bar(abs) and that pyrolytic carbon was produced in a fixed bed reactor at 1200 °C at 1.0-1 .2 bar(abs) by decomposition of methane and by deposition on petroleum coke as carrier material having a particle size of 1-4 mm. In WO 2021 / 122503 the granular pyrolytic carbon was produced by decomposition of natural gas and deposition on calcined petroleum coke carrier material (the carrier having a particle size of 0.5-2.5 mm, a sulfur content of 1.1 wt.- % and a real density in xylene of 2.09 g / cm3) in a fluidized bed at temperatures from 1100-1300 °C and at pressures from 1-2 bar(abs). The figures disclose a smooth surface of the pyrolytic carbon, whereas the surface of the biochar was less smooth. In WO 2023 / 57242 methane pyrolysis was performed in a fixed-bed reactor that was heated externally to 1450°C (Example 1) and 1200°C (Example 3). Pyrolysis was performed for 170 minutes at a volume flow of methane of 60 Nl / h. A methane conversion of 98% was obtained in Example 1 and for 90 minutes at a volume flow of methane of 120 Nl / h obtaining a conversion of 83% in Example 3. 2. Inventive examples 2.1 Inventive example I: Synthesis of anisotropic pyrolysis carbon in fixed be reactors Multiple cycles of pyrolysis were carried out on a fixed-bed of solid carbon granule using NeedleCoke Resonac, 1.7 - 3.35 mm, as carrier material in the initial cycle 1. After each cycle the carbon bed was removed from the reactor, small samples were taken for analysis, and the rest of the bed was mixed and used in following cycles. The operation conditions of the cycles were alternated in the following way: In cycle 1, 3, and 5 pyrolysis was carried out at 1 bara (bar absolute), 1400 °C using a feed mixture of 20 % natural gas in hydrogen for 2 h each. The cycles 1, 3, and 5 were carried out in fixed bed reactor 1 filled over a total height of 560 – 467 mm with the entire fraction of solid carbon granule (fresh carrier in cycle 1, material from cycle 2.1 + 2.2 for cycle 3 and material from cycle 4.1 and 4.2 for cycle 5) in a ceramic tube with an inner diameter of 50 mm. The total amount of carbon (and the resulting bed height) was reduced from cycle to cycle since samples were taken for analy- sis. In cycle 2.1, 2.2, 4.1, 4.2, 6.1, and 6.2 pyrolysis was carried out at 10 bara (bar absolute) and 1300 °C using a feed mixture of 20 % methane in hydrogen. In the cycles 2.1 and 2.2 pyrolysis was conducted for 1 h, in the cycles 4.1, 4.2, 6.1, and 6.2 pyrolysis was conducted for 1.25 h each. The cycles 2.1, 2.2, 4.1, 4.2, 6.1, and 6.2 were carried out in fixed bed reactor 2 filled over a total height of 550 - 560 mm with a fraction of the solid carbon granule in a ceramic tube with an inner diameter of 40 mm. Since fixed-bed reactor 2 has a smaller volume than fixed-bed reactor 1, the cycles 2, 4, and 6 were carried out in 2 steps each: In the first step of the cycles (2.1, 4.1 and 6.1) 2 / 3 of the mixed carbon granule resulting from cycles 1, 3, and 5 respectively were used as fixed bed. In the second step of the cycles the third part of the mixed carbon granule resulting from cycles 1, 3, and 5 were placed towards the feed inlet part of the fixed bed and the fixed-bed as filled up with roughly the upper halt of the material from cycles 2.1, 4.1, 6.1 till the total volume of ~ 555 mm was filled. Since less material is deposited under the used conditions in the upper half than in the lower half, in this way a more ho- mogenous total deposition over the entire fraction of particles was achieved. By the alternating variation of the operation conditions a material consisting of multiple layers of pyrolysis carbon with alternating properties deposited on a NeedleCoke core was synthesized (see Figure 1). As can be seen in the map- pings of the e-modulus and hardness a controlled variation of the physical properties of the respective pyrolysis car- bon layer is achieved by the alternation in the operation conditions (T and p). Table 1: Measurement of E-Module and Hardness of the different layers by nanoindentation Pyrolytic carbon Average E- Standard deviation Averaged Standard devia- SEM layer Module [GPa] E-Module [GPa] Hardness tion Hardness [GPa] [GPa] core 15 2 1,8 0,3 - Layer 1 - - - - - Layer 2 8,5 1 0,7 0,1 Coral (Fig.2a) Layer 3 13 1,5 1,6 0,2 Smooth (Fig.2b) Layer 4 8,5 1 0,7 0,1 Coral (Fig.2c) Layer 5 12 1 1,5 0,2 Smooth (Fig.2d) Layer 6 8,5 1 0,7 0,1 Coral (Fig.2e) 2.2 Inventive example II: Synthesis of anisotropic pyrolysis carbon in fixed be reactors Pyrolysis of natural gas was performed in a direct heated moving bed reactor. The Reactor had a length of 3 m and an inner diameter of 200mm. The Reactor was initially filled with calcined petroleum coke (CPC) with a particle size distribution of 2 – 4 mm. The reactor was direct electrically heated to temperatures of 1250 °C. To compensate heat losses, the rector was additionally wall heated. The reactor was continuously operated, and the carbon granules were recycled and passed 24 times through the reactor During the campaign, the natural gas concentration was varied between 6 vol% and 16 vol%. The remaining gas was H2. Figure 2 shows a SEM image of the cross section of a carbon particle after 24 pyrolysis passes. The different shades of grey correspond to the variation of the natural gas concentration which results in a variation in the carbon morphology. This is underlined by Table 2 which shows the respective E-Modulus and hardness of the Pyro-C layer. Table 2: Measurement of E-Module and Hardness of the different layers by nanoindentation Pyrolytic carbon Average E-Module Standard deviation Averaged Hardness Standard deviation layer [GPa] E-Module [GPa] [GPa] Hardness [GPa] core 14 2 0,9 0,4 Layer 1 8,6 1 0,7 0,2 Layer 2 13 1 0,8 0,2 Layer 3 7 1 0,6 0,2 Layer 4 6 0,6 0,4 0,1 Layer 5 7 1 0,6 0,2 Layer 6 8 1 0,7 0,1 2.3 Comparative example Six cycles of pyrolysis were carried out on a fixed-bed of solid carbon granule using NeedleCoke Resonac 1.7 - 3.35 mm as carrier material in the initial cycle 1. After each cycle the carbon bed was removed from the reactor, small samples were taken for analysis, and the rest of the bed was mixed and used in the following cycles. The height of the fixed bed formed by solid carbon granule was gradually reduced from cycle to cycle ranging from 572 – 505 mm since carbon samples were taken for analysis. The carbon fixed bed was filled in an externally heated ceramic tube with an inner diameter of 50 mm. In all cycles pyrolysis was carried out at 1 bara (bar absolute), 1400 °C using a feed mixture of 20 % natural gas in hydrogen for 2 h each. In each cycle an averaged deposition rate of ~5.4 – 6.6 % was achieved totaling an overall deposition rate of ~ 35 %. By using constant operation conditions, a homogeneous pyrolytic carbon layer deposited on a NeedleCoke core was synthesized (see Figure 3). No differentiation between pyrolytic carbon of different cycles can be made by means of nanoindentation and SEM measurements. Table 3: Measurement of E-Module and Hardness of the different layers by nanoindentation Pyrolytic carbon Average E-Module Standard deviation Averaged Hardness Standard deviation layer [GPa] E-Module [GPa] [GPa] Hardness [GPa] core 22 5 2,5 1 Single Layer 10,5 1,5 0,7 0,2 3 Measurement 3.1 Nanoindentation The mechanical characterization of the samples at the micro and nano scales was performed by nanoindentation test of hardness (H) and elastic modulus (E) in accordance with the international standard ISO 14577. The nanoindenta- tion measurement of E and H was performed in two different test modes: 1) quasi-static test (G200 indenter, KLA). At least 15 positions were tested on the area of interest. 2) mapping of E and H distribution were collected using NanoBlitz 3D mode (iNano indenter, KLA). The area of the mapping was 200x200 µm with 100x100 points. Diamand tip with Berkovich geometry was used for both test modes. The area function of the Berkovich tip was cali- brated before the test using fused quartz reference material. The tests were load controlled with max load of 1 mN. The analysis of the nanoindenter mappings was conducted using clustering. The number of clusters was determined individually based on the measurement results of the respective sample. Initially, the clusters were created based on the measurements of the elastic modulus, and then applied to the hardness data to obtain a consistent cluster. Alter- natively, a profile was applied across a mapping image at the area of interest to confirm the values obtained from the cluster validation. Sample preparation for nanoindenation test: The samples for nanoindentation measurement were prepared using a Buehler AutoMet 250 polishing machine. Firstly, the particles were embedded in EpoFix resin (Struers) using embedding mold (Buehler). After curing, three grinding steps were performed by polishing machine using abrasives with grit sizes of 80, 320, and 1200. This was followed by three polishing steps using diamond suspensions of 3 µm and 1 µm and an aluminum suspension of 0.25 µm. 3.2 HG Porosity In Mercury Intrusion Porosimetry (MIP), a sample is subjected to increasing pressure using mercury as the intrusion fluid. The pressure is gradually increased, forcing the mercury to penetrate into the pores of the material. As the pressure increases, the mercury intrudes into smaller and smaller pores, allowing for the determination of the pore size distribution. The amount of mercury intruded into the sample is measured, and this data is used to calculate the pore volume, pore size distribution and pore surface assuming a cylindrical pore geometry. The maximum pressure was set to 4.13 *10^8 Pa which corresponds to a minimum pore size of 3nm. The measurements were performed on a Micromeritics Autopore 5 system with an SOP according to DIN 66133 and DIN ISO 15901-1. 3.3 L-Parameter (perceptual lightness) By following these instructions, you can accurately obtain CIELAB values for powder or granulate samples using your photospectrometer, ensuring precise color measurement and analysis. The CIELAB color space, also known as (L*, a*, b*) expresses color as three values: L* for the perceptual lightness and a* and b* as color coordinates defined as red-green and yellow-blue axes. The CIELAB values (L*, a*, b*) are derived from spectral data using the CIE 1976 (L*, a*, b*) color space, often re- ferred to as CIELAB. The process of obtaining these values from spectral data is standardized by the CIE (Commis- sion Internationale de l'Éclairage, or International Commission on Illumination). The specific standard that details the conversion of spectral data to CIELAB values is the CIE Publication 15:2018, also known as "Colorimetry, 4th Edi- tion." The perceptual lightness can be analyzed either for the cross section or for the surface of particles / granulate sam- ples. By following the following instructions, you can accurately obtain CIELAB values for powder or granulate sam- ples using your photospectrometer, ensuring precise color measurement and analysis. In order to obtain spectral data across the visible wavelength range (typically 360nm to 780 nm) for powder or granu- late samples, a spectrophotometer with d / 8° geometry in vertical arrangement is needed (e.g. Datacolor Spectro 1000V). The spectrophotometer should be set in such a way that the specular reflection of the sample would not be included in the relevant spectral response (“specular excluded” operation mode). The powder or granulate sample should be presented to the spectrometer in a flat-bottom transparent shell, which is clean and has no scratches or roughness generating own scattering or color. The powder amount in the shell should be high enough, providing that no light is passing through, either from the spectrophotometer to the ambient, nor from the ambient to the spectrophotometer. Choose a wide aperture to the integrating sphere of the spectrophotometer. A very suitable aperture has 30 mm opening diameter. Choose D65 as standard illuminant. Choose the 2° standard observer angle, based on the CIE 1931 standard colori- metric observer. Calibrate the spectrophotometer. Check the flat-bottom shell against dirt or scratches. Measure L*, a*, b* values of the empty shell. A suitable shell will have values L* < 2, a* and b* < 1. Fill the powder or granulate into the shell in a sufficient amount, which will provide a completely opaque layer on the bottom of the shell. Depending on the powder or granulate particle size, the layer may need several centimeters thickness. Trigger the spectral measurement. Compute the L*, a*, b* values. 3.3 SEM Surface Morphology Characterization Method Experimental / Image Analysis The following paragraph describes the SEM-based classification of the morphology of pyrolytic carbon by automated image analysis. A) Microscopy 1) Coat sample with approx.10nm of Pt in a sputter coater. 2) Set the scanning electron microscope to secondary electron imaging mode. 3) Adjust contrast / brightness of the detector in order to cover the whole dynamic range of the imaging sys- tem. Avoid under / over exposure and the corresponding clipping of image information. 4) Take 15 images at a magnification of 50kx (image resolution from 1024x768 to 1536x1024 pixel; pixel size from 1.80-2.25 nm / pixel; covered sample area 1.75-2.60 µm² / image) at a random, representative position containing pyrolytic carbon. Tif files without any annotations / scalebars are required. B) Image Analysis The image analysis workflow is implemented as script in ImageJ (freeware, open source, use FIJI distribution, script attached). Image analysis results can be processed with any software that can read .csv files like e.g. MS Excel. Set the pixel size in the first line of the analysis script [nm]. Run the automated image analysis as described in detail below. The image analysis is based on 4 analysis runs whereof 5 descriptors are extracted. The descriptors are com- bined to distinguish between coral and non-coral morphology. For 15 images the scripts result in 4x15=60.csv files from which a list of descriptors must be extracted for classi- fication according to the table below. The csv files contain a list of many different descriptors for each detected particle. Only a few of the descriptors are used for classification. List of analyses: Adopted particle detection algorithm (NanoDefine ParticleSizer Plugin for ImageJ) which is configured to search for particulate structures in the image. Based on the contrast setting, these particle structures can either be the voids between coral ridges or the coral structure itself. For classification the area equivalent circle diameter (ECD) of the detected particle structures is employed. “Min. OTB intensity difference (8bit)” in the following “Min OTP” is set to different values and the image contrast is either inverted (IC) or not (SC), depending on if the al- gorithm searches for voids between the coral ridges or the coral structure itself. The 4 analysis runs are: Analysis run 1 (“RUN1_IC016”): Min OTP =16 with inverted contrast Analysis run 2 (“RUN2_SC016”): Min OTP =16 Analysis run 3(“RUN3_IC128”): Min OTP =128 with inverted contrast Analysis run 4 (“RUN4_SC128”): Min OTP =128 Descriptor 1 (void size): Arithmetic mean area equivalent circle diameter (entry 13 in the .csv) of all particles in Analysis run 1. It de- scribes the mean size of the voids between the coral structures. Descriptor 2 (total area coral): The sum of the area (entry 6 in the .csv) of all detected particles of Analysis run 2. It describes the total area of coral structures in the image based on Analysis run 2. Descriptor 3 (D3, void area): The sum of the area (entry 6 in the .csv) of all detected particles of Analysis run 3. It describes the total area of voids between coral structures in the image based on Analysis run 3. Descriptor 4 (D4, light coral area): The sum of the area (entry 6 in the .csv) of all detected particles of Analysis run 4. It describes the total area of particularly light coral structures in the image based on Analysis run 4. Light coral area is a subset of total coral area (D2). Light coral area (D4) differentiates from total coral area (D2) by a particular lightness, which is defined by an intensity beyond Min-OTP of 128. Descriptor 5 (coral shape): Arithmetic mean solidity (entry 21 in the .csv) of Analysis run 4. It describes the shape of the detected coral structures and is defined by the ratio of the area enclosed by the outer contour of the particle (A) and the area enclosed by the convex hull of the outer contour of the particle (C). D5 = A / C. Definition matrix of coral morphology: all must apply Descriptor 1 Descriptor 2 Descriptor 3 Descriptor 4 Descriptor 5 (void size) [nm] (total coral (void area) (light coral (coral shape) area) [µm²] area) [µm²] [µm²] min 65 0.6 0.05 0.05 0.900 max 110 2.5 2.50 2.50 0.975 Definition matrix of smooth morphology: Descriptor 1 Descriptor 2 Descriptor 3 Descriptor 4 Descriptor 5 (void size) [nm] (total coral (void area) (light coral (coral shape) area) [µm²] area) [µm²] [µm²] min 0 max 0.049 Table 1: Definition of coral and smooth morphology Classify all 15 images according to Table 1. For coral morphology all descriptors must independently be in the given range. For smooth morphology only descriptor 3 is relevant for classification. The result is valid if at least 12 out of 15 images have the same morphology (either coral or non-coral). Minimum software requirements • Fiji 2.3.0 / ImageJ 1.53q (https: / / imagej.net / ) o Required Plugins: ^ ParticleSizer 1.0.9 (https: / / imagej.net / imagej-wiki-static / ParticleSizer) o Required sites that need to activated for Installation: Update-> Manage Update Sites: ^ http: / / sites.imagej.net / NDef-psizer ^ http: / / sites.imagej.net / Biomedgroup • Any data calculation software that can read CSV-files. (Microsoft Excel or similar) Note: The classification was applied to images of 320 different samples with a detection accuracy of 90% compared with expert judgement.

[0003] Software setting requirements Run the Setup macro script once (table 2). Setup macro for ImageJ call("ij.Prefs.set", "ndef.convexity", -1); call("ij.Prefs.set", "ndef.ConvexityThreshold", 0.9); call("ij.Prefs.set", "ndef.doIrregularWatershed", "true"); call("ij.Prefs.set", "ndef.doSelectRegion", "false"); call("ij.Prefs.set", "ndef.ellipseAspectRatioRange", -1); call("ij.Prefs.set", "ndef.ellipseLongAxisRange", -1); call("ij.Prefs.set", "ndef.ellipseShortAxisRange", -1); call("ij.Prefs.set", "ndef.feretMinRange", -1); call("ij.Prefs.set", "ndef.filterSolidity", -1); call("ij.Prefs.set", "ndef.invertImages", "true"); call("ij.Prefs.set", "ndef.localThresholdWindowSize", -1); call("ij.Prefs.set", "ndef.minEllipseAspectRatio", 100); call("ij.Prefs.set", "ndef.minEllipseLongAxis", 5); call("ij.Prefs.set", "ndef.minEllipseShortAxis", 5); call("ij.Prefs.set", "ndef.minFeretMin", -1); call("ij.Prefs.set", "ndef.minSize", -1); call("ij.Prefs.set", "ndef.noDenoise", "false"); call("ij.Prefs.set", "ndef.noPlotting", "true"); call("ij.Prefs.set", "ndef.objectIntensityThreshold", -1); call("ij.Prefs.set", "ndef.recordProcess", "false"); call("ij.Prefs.set", "ndef.rollingBallRadius", -1); call("ij.Prefs.set", "ndef.showBinaryResult", "false"); call("ij.Prefs.set", "ndef.sizeRange", -1); call("ij.Prefs.set", "ndef.skipSmoothing", "false"); call("ij.Prefs.set", "ndef.smoothingFactor", 1); call("ij.Prefs.set", "ndef.useEllipseFittingMode", "false"); call("ij.Prefs.set", "ndef.useSingleParticleMode", "false"); run("Set Measurements...", "area mean standard modal min centroid center perimeter bounding fit shape fer- et's integrated median skewness kurtosis area_fraction stack display redirect=None decimal=5"); Table 2 – ImageJ – Setup macro script

[0004] Image analysis script pixelsize = 0.0; / / nm / / PIXELSIZE MUST BE ADJUSTED RELATED TO YOUR IMAGES IN NANOMETERES input = getDirectory("Directory containing files "); / / OUTPUT-DIR WILL BE INPUT-DIR, CHANGE IF WANTED output = input; suffix =".tif"; list = getFileList(input); run("Clear Results"); strthreshold1 = "RUN1_IC016"; call("ij.Prefs.set", "ndef.invertImages", "true"); call("ij.Prefs.set", "ndef.objectIntensityThreshold", -1); processFolder(input, strthreshold1); strthreshold2 = "RUN2_SC016"; call("ij.Prefs.set", "ndef.invertImages", "false"); call("ij.Prefs.set", "ndef.objectIntensityThreshold", -1); processFolder(input, strthreshold2); strthreshold3 = "RUN3_IC128"; call("ij.Prefs.set", "ndef.invertImages", "true"); call("ij.Prefs.set", "ndef.objectIntensityThreshold", 128); processFolder(input, strthreshold3); strthreshold4 = "RUN4_SC128"; call("ij.Prefs.set", "ndef.invertImages", "false"); call("ij.Prefs.set", "ndef.objectIntensityThreshold", 128); processFolder(input, strthreshold4); function processFolder(input, strthreshold) { list = getFileList(input); list = Array.sort(list); for (i = 0; i < list.length; i++) { if(File.isDirectory(input + File.separator + list[i])) processFolder(input + File.separator + list[i]); if(endsWith(list[i], suffix)) processFile(input, output, list[i], strthreshold); } } function processFile(input, output, file, strthreshold) { run("Clear Results"); open(input + File.separator + file); run("Enhance Contrast", "saturated=0.35"); run("Apply LUT"); run("Set Scale...", "distance=1 known="+pixelsize+" unit=nm"); run("Particle Sizer"); run("Show Overlay"); saveAs("jpeg", input + File.separator + strthreshold + "_" + file); close(); selectWindow("Results"); saveAs("Results", input + File.separator + strthreshold + "_" + file + ".csv"); } Table 3 – ImageJ – Analysis macro script

[0005] 3.5 Characterization of different layers Analysis methods said require different particle preparation methods, resulting in different ways to use them for the analysis of the layering structure. Characterization of surface morphology based on SEM pictures (s.3.4) requires an intact particle surface. Hence, if different layers shall be characterized by the surface morphology, particle samples must be removed from the pyroly- sis process for SEM analysis at adequate points in time. Preferably, particle samples are removed for SEM analysis after the process conditions are adjusted to produce a morphology different from the previous one (coral -> smooth or smooth -> coral) and after the process ran for a sufficiently long time at such conditions to produce a sufficiently thick layer of pyrolysis carbon showing the altered morphology. Characterization of surface morphology based on the L-parameter (s.3.3) is performed on the intact particle surface. Hence, if different layers shall be characterized by the L-parameter, the same preconditions apply as described in the previous paragraph for the SEM analysis. However, the analysis of the L-parameter could also be applied for the cross section of particles (s. Figure 1 d). In this case, the particle can be removed at any time of the process provided that at least two different layers with sufficient thickness were produced before performing the analysis of the cross section. Nanoindentation (s.3.1) is performed for the cross section of particles. Hence, the same preconditions apply as de- scribed in the previous paragraph regarding the analysis of the L-parameter for the cross section of particles. If other methods to analyze the hardness and e-module shall be applied to characterize the surface of particles, the same preconditions apply as described in the previous paragraphs regarding the surface analysis using the analysis of SEM pictures and the L-parameter.

Claims

Claims:

1. Pyrolytic carbon particle, which is obtained by a thermal decomposition of hydrocarbons, and said pyrolytic carbon particle has the following properties: - Carbon content 98 to 99.99 wt.-%, - Particle size from 0.1 to 10 mm, - Ash content 0 to 2 wt.-%, - Specific surface area 5 to 25 m2 / g, - Median pore diameter (volume) from 0.005 to 1 µm, and wherein said pyrolytic carbon particle comprises at least two layers of pyrolytic carbon having different carbon surface morphologies, wherein each morphology is defined by the following parameters: - e-module being in the range of 5 to 35 GPa and - hardness being in the range of 0.2 to 5 GPa, and - L-parameter of colour from 10 to 45 and wherein at least one of the parameters of a first morphology of a first layer of pyrolytic carbon deviates from 20 to 300% of the respective parameter of a second morphology of a second layer of pyrolytic carbon, wherein the first layer and the second layer are adjacent to each other and wherein the thickness of each layer is 1 µm to 5 mm.

2. Pyrolytic carbon particle according to claim 1, wherein the pyrolytic particle has 5 to 100 layers.

3. Pyrolytic carbon particle according to claim 1 or 2, wherein the at least one of the parameter of a first morphol- ogy of a first layer of pyrolytic carbon deviates from 40 to 150 % of the respective parameter of a second mor- phology of a second layer of pyrolytic carbon, wherein the first layer and the second layer are adjacent to each other.

4. Pyrolytic carbon particle according to any of claims 1 or 3, wherein the thickness of each layer is 10 µm to 100 µm.

5. Pyrolytic carbon particles according to any of claims 1 or 4, wherein the carbon content is 99.5 to 99.99 wt.-% and the ash content is 0 to 0.5 wt.-%.

6. Pyrolytic carbon particles according to any of claims 1 or 5, wherein the layer alternate between coral and smooth surface morphology and wherein coral morphology is defined by - E-Modul from 5 to 25 GPa, - Hardness from 0.2 to 4 GPa, - L-parameter of colour from 10 to 20 - Coral Surface morphology defined by SEM surface morphology method by the following descriptor pa- rameters D1-D5: o D1, void size, from 65 to 110 nm o D2, total coral area, from 0.6 to 2.5 µm² o D3, void area, from 0.05 to 2.5 µm² o D4, light coral area, from 0.05 to 2.5 µm² o D5, coral shape, from 0.9 to 0.

975. and wherein smooth morphology is defined by: - E-Modul from 5 to 35 GPa, - Hardness from 0.7 to 5 GPa, - L-parameter of colour from 25 to 45, - Smooth surface morphology defined by SEM surface morphology method defined by the following de- scriptor parameter D3: o D3, void area, from 0 to 0.049 µm².

7. Pyrolytic carbon particles according to any of claims 1 or 6, wherein the outer layer of said pyrolytic carbon particle has a coral surface morphology.

8. Pyrolytic carbon particles according to any of claims 1 or 6, wherein the second layer covers the outer surface of the first, underlying, layer by at least by 80 % of the outer surface of the first layer.

9. A process of producing said pyrolytic carbon particle according to any of claims 1 to 8 which comprise at least two layers of pyrolytic carbon having different carbon surface morphology by decomposition of hydrocarbons in a fixed, fluidized or moving bed at a pressure of 1 to 30 bar and a temperature of 800 to 1500°C and a hy- drocarbon concentration in the feed of 2.5 to 100 vol.-%, wherein the decomposition is conducted stepwise with at least two different, optionally alternating, process conditions; wherein one of the at least two different process condition differs in at least one of the following process parameters to the other process condition: - at least 20 °C difference in temperature and / or - at least 100 mbar difference in pressure and / or - at least 5 vol.-% difference in hydrocarbon concentration, and wherein the respective process condition is kept until a thickness of the pyrolytic layer of said carbon mor- phology of 1 µm to 5 mm is reached.

10. Process according to claim 9, wherein at least two process conditions differ in at least one of the following parameters to the other process condition: - at least 50 °C difference in temperature and / or - at least 500 mbar difference in pressure and / or - at least 10 vol.-% difference in hydrocarbon concentration.

11. Process according to claims 9 or 10, wherein said different process conditions are kept for 30 min to 5 hours.

12. Process according to any of claims 9 to 11, wherein the one process conditions are: at a pressure of 2.5 to 25 bara, bar absolute, and a temperature of 1000 to 1450°C and a hydrocarbon concentration in the feed of 10 to 50 vol.-%; and wherein the different other process conditions are: at a pressure of 0.7 to 1.5 bara, bar abso- lute, and a temperature of 1350 to 1500°C and a hydrocarbon concentration in the feed of 10 to 80 vol.-%.

13. Process according to any of claims 9 to 12, wherein said thermal decomposition gives a hydrogen containing product stream and wherein 20 to 90 Vol.-% of said hydrogen-containing product stream is recycled internally to said reaction chamber.

14. Process according to any of claims 9 to 13, wherein the material bed is in the form of a moving bed and wherein the material is guided in countercurrent to the hydrocarbon feed.

15. Process according to any of claims 9 to 14, wherein said process is conducted in a plant comprising at least two reactors, wherein in all reactors a decomposition of hydrocarbons in a fixed, fluidized or moving bed is conducted, wherein the process conditions of the decomposition differ from reactor to reactor and the process condition is fixed per reactor, and wherein at least part of the pyrolytic carbon formed in one of the reactors is passed to another reactor and used as bed material in said other reactor and the process conditions of the at least one reactor differ in at least one of the following process parameters to the other reactor: at least 20 °C difference in temperature and / or at least 100 mbar difference in pressure and / or at least 5 vol.-% difference in hydrocarbon concentration and wherein solid carbon is kept in said reactor until a thickness of the pyrolytic layer of said carbon morphol- ogy of 1 µm to 5 mm is reached.

16. Composition comprising a mixture of pyrolytic carbon particles according to any of claims 1 to 7 and a binder.

17. Blend composition comprising a mixture of (i) petroleum coke and / or bio char in a content of 5 to 50 weight-% and (ii) pyrolytic carbon particles according to any of claims 1 to 7 in a content of 50 to 95 weight-% in view of the total weight of the blend composition.

18. Electrode recipe comprising a mixture of (i) a blend composition of petroleum coke and pyrolytic carbon parti- cles according to any of claims 1 to 7, (ii) anode butts and / or scrap and (iii) binder material.

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