Process to minimize filament formation or agglomeration in cracking or pyrolysis processes

Abstract

The present invention comprises a process to minimize filament formation or agglomeration in cracking or pyrolysis process of hydrocarbons that includes a fixed, fluidized or moving bed, wherein the bed comprising solid material is pretreated and passivated with an atmosphere of hydrogen and / or inert gases before starting the production mode of the cracking or pyrolysis process of hydrocarbons or it is treated temporarily between two production process mode steps of said cracking or pyrolyzing of hydrocarbons, wherein the time and temperature of said treatment is characterized by the formula T (min * °C) = time (min) x temperature (°C) and T is at least 10000 min * °C and wherein the temperature is at least 500°C, wherein during said treatment the carbon deposition rate of the cracking or pyrolysis process, if any, is below 2 wt.-%, and wherein the atmosphere of said treatment contains 70 to 100 Vol.-%, related to the total atmosphere used for the treatment, of hydrogen and / or inert gases and 30 to 0 Vol.-% of gaseous hydrocarbons.

Description

[0001] Process to minimize filament formation or agglomeration in cracking or pyrolysis processes Description The present invention comprises a process to minimize filament formation or agglomeration in cracking or pyrolysis process of hydrocarbons that includes a fixed, fluidized or moving bed, wherein the bed comprising solid material is pretreated and passivated with an atmosphere of hydrogen and / or inert gases before starting the production mode of the cracking or pyrolysis process of hydrocarbons or it is treated temporarily between two production process mode steps of said cracking or pyrolyzing of hydrocarbons, wherein the time and temperature of said treatment is charac- terized by the formula T (min * °C) = time (min) multiplied by temperature (°C) and T is at least 10000 min * °C and wherein the temperature is at least 500°C, wherein during said treatment the carbon deposition rate of the cracking or pyrolysis process, if any, is below 2 wt.-%, and wherein the atmosphere of said treatment contains 70 to 100 Vol.- %, related to the total atmosphere used for the treatment, of hydrogen and / or inert gases and 30 to 0 Vol.-% of gase- ous hydrocarbons. State of the art Hydrogen is considered potentially the cleanest energy in this century against the background of carbon neutrality beside being a fundamental feedstock for a (petro-)chemical industry. Currently in industry, hydrogen is produced by reforming hydrocarbons, such as coal and natural gas, and only to a small extent by electrolysis of water and me- thane pyrolysis. While reforming of hydrocarbons emits huge amounts of CO2, hydrogen production by water elec- trolysis is relatively expensive and requires high amounts of renewable power. The technology of methane pyrolysis requiring much less renewable power than water electrolysis; however, the methane pyrolysis is still under develop- ment. The generic term methane pyrolysis covers a wide range of different process technologies. The best known and most advanced of these are: Plasma pyrolysis, Metal melting / Metal salt melting, Moving or fluidized bed process, catalytic process, partial combustion. These technologies differ in the form of the energy used (thermal, electrical, etc.), the process conditions (temperature, pressure, etc.), the catalysts and / or auxiliary materials used, the process flow and the technical readiness level (TRL). In the pyrolysis of hydrocarbons solid carbon is formed. In some concepts the solid carbon is deposited on a solid carrier: CH 409890 and US 2982622 disclose a process of converting hydrocarbon in a high temperature conversion at 980 to 1650° C into light products and high-grade coke by contact with electrically heated solid particles. It is disclosed that a portion of the hot product gas, e.g., hydrogen, may be recycled to serve to heat the incoming feed. This is particular desirable when the feed is a liquid and the recycle serves as a vaporizing medium. WO 2019 / 145279 and WO 2020 / 200522 disclose a reactor and a method for carrying out an endothermic reaction like hydrocarbon pyrolysis by using a moving bed technology with electric heating of solid particles. In order to achieve optimal heat integration the heat capacity flows of the gas and solid particle flows are adapted to each other to generate an upper and a lower heat integration zone. US 2021 / 0331918 discloses a system and methods for conversion of hydrocarbons to hydrogen by pyrolysis in a conversion reactor that contains a plurality of sequential fluidized beds. The fluidized beds are arranged so that the coke particles forming the fluidized bed move in a counter-current direction relative to the gas feed and / or product. In reactor concepts, in which the solid carbon is deposited on a solid carrier material, like in fixed, fluidized or moving bed technologies, the deposition of carbon can result in agglomeration of carrier bed particles. Several negative aspects are associated with this agglomeration process. In fixed bed reactors, stronger agglomerated beds require a more complex, slower procedure to remove the carrier bed. In moving bed reactors, a higher level of agglomeration between carrier particles can lead to a blockage of the solid flow. In fluidized bed reactors, large agglomerates may no longer be fluidized, thus disrupting the fluidization behavior of the bed ending with a collapse of the fluidized bed. In addition, the formed filaments and agglomerates might have different properties (morphology, density, crystalline structure) compared to the targeted carbon bulk structure and thus reduces the quality and value of the pyrolytic deposited carbon material. Most of the disclosed experiments on methane decomposition are still conducted on a laboratory scale in a batch mode in fixed-bed reactors or fluidized bed reactors for a very short period of time. The main problem to cross the gap between the laboratory scale and its industrial implementation in a fixed, moving or fluidized bed is the impact of deposition of coke and other solids on the process in industrial dimension and time scale. The problem of coke deposition in the reactor system, especially on the reactor wall, is already mentioned and partly solved in the state of the art: WO 2023 / 057242 discloses a method for carrying out hydrocarbon pyrolysis by using a moving bed technology with electric heating of carbonaceous material having a porosity of 30 to 70 vol.-% and a high carbon content of 99 wt.-% to 100 wt.-% as metal impurities tend to resolve from the carbonaceous material and deposit on the reactor walls and tends to form agglomerates. DE 102019130600 discloses a method for producing and carbon from hydrocarbons in an electric heated reactor. An inert gas component is supplied in the reaction cross section between the electrodes. By introducing an inert gas component, a deposition of carbon in this region of the internal reactor wall is prevented. WO 2022 / 081170 discloses a methane pyrolysis process using stacked fluidized beds with electric heating of coke particles. It is disclosed that the electrical heating is performed above the reaction zone in a hydrogen-rich environ- ment in order to reduce, minimize, or eliminate formation of coke on the surfaces of the electrical heater. WO 2024 / 115488 discloses the use of by-products streams from a cracking process as feedstock for a methane pyrolysis process. Said methane pyrolysis is operated in a moving bed reactor at 800 to 1500°C, wherein the by- products streams used as feedstock is preferably diluted by a recycled hydrogen product stream resulting in a feed- stock stream that contains 70 to 99 vol.-% hydrogen and 1 to 30 vol.-% hydrocarbons. However, the problem that deposition of carbon can result in agglomeration of carrier bed particles is still unsolved. Hence, for these reactor types a higher level of agglomeration is associated with a reduced production capacity due to longer downtimes and / or reduced carbon deposition rates per batch / moving bed cycle to mitigate agglomeration problems. Furthermore, the reactor equipment can be damaged in the removal process of a strongly agglomerated carrier bed. The amount of carbon that can be deposited per pass through reactor without reaching a critical level of agglomera- tion / blockage of the solid flow is a crucial parameter of the overall economics in hydrocarbon pyrolysis. The increase in the achievable carbon deposition without reaching a critical level of agglomeration directly increases the produc- tion capacity with all associated advantages regarding the Capital Expenditures (CapEx) and the Operational Ex- penditures (OpEx) of the process. Task It is an object of the present invention to minimize the risk of agglomeration of carrier particles in cracking and pyroly- sis processes. By reducing or even preventing the formation of filaments the level of agglomeration of a carrier parti- cle is reduced at the same amount of carbon deposited in a cycle / batch. Another objective of the invention is to max- imize the deposition of carbon per reactor volume in order to maximize the hydrogen production capacity per reactor volume. Furthermore, another objective of the present invention is to enable the usage of carrier materials with a reduced quality as carrier material in fixed, fluidized or moving bed reactors in cracking or pyrolysis processes. Invention The present invention comprises a process to minimize filament formation or agglomeration in cracking or pyrolysis process of hydrocarbons that includes a fixed, fluidized or moving bed, wherein the bed comprising solid material is pretreated and passivated with an atmosphere of and / or inert gases before starting the production mode of the cracking or pyrolysis process of hydrocarbons or it is treated temporarily between two production process mode steps of said cracking or pyrolyzing of hydrocarbons, wherein the time and temperature of said treatment is charac- terized by the formula T (min * °C) = time (min) x temperature (°C) and T is at least 10000 min * °C: T = time x temperature and wherein the temperature is at least 500°C, wherein during said treatment the carbon deposition rate of the cracking or pyrolysis process, if any, is below 2 wt.- %, and wherein the atmosphere of said treatment contains 70 to 100 Vol.-%, related to the total atmosphere used for the treatment, of hydrogen and / or inert gases and 30 to 0 Vol.-% of gaseous hydrocarbons. It was found that the formation of solid carbon with a certain morphology, named carbon filaments, results in a higher tendency for bed agglomeration and / or blockages to occur in pyrolysis processes. Treatment process conditions were found that can be used to minimize the formation of carbon filaments and thus, to reduce the degree of carrier bed agglomeration and the associated problems. The purpose of the pre-treatment is to passivate the surface of the carrier. Passivation involves removing reactive, oxygen-containing groups from the surface, reducing the surface concentration of metallic elements, and / or coating the surface with a layer of pyrolytic carbon very mild operation conditions. The removal of oxygen-containing compo- nents is achieved through gasification using reducing gaseous reactants. The reduction of metallic elements on the surface can be accomplished by sintering, forming volatile compounds, or applying a layer of pyrolytic carbon. Definition C1 stands for methane. C1+ stands for all hydrocarbons having at least one C-atom 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- containing product stream. Detailed Description of the Invention Cracking or pyrolysis process of hydrocarbons The production mode, the process of cracking or pyrolyzing hydrocarbons is well described in the state of the art. Typically the pyrolysis and cracking operate at 500 to 3000°C in a pressure range from atmospheric pressure to 30 bar. Typical hydrocarbon feedstocks for the pyrolysis are gaseous hydrocarbons, like natural gas, methane, ethane, biogas, like biomethane. Typical feedstocks for cracking processes are gaseous and liquid hydrocarbons like ethane, propane, naphtha, bionaphtha. Pretreatment or temporarily treatment In the present invention, before the process step of cracking or pyrolyzing of hydrocarbons or temporarily between two process steps of cracking or pyrolyzing of hydrocarbons, the bed is pretreated or temporarily treated. 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, the residence time in said treatment atmosphere, 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 preferably 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, even more preferably in the range of 30 min to 600 min. If a mov- ing bed is used, the time / period of said treatment 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 passages, even more prefer- ably 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 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 pyrol- ysis 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. The type of pre-treatment depends on the carrier material: For calcined petcoke, the preferred pretreatment conditions are as follows: Temperature: Preferably 600°C to 1200°C, more preferably 600°C to 1000°C, and especially 600°C to 800°C. In view of a moving bed reactor: Resi- dence time in the reaction zone: Preferably 90 to 1080 minutes, with a preference for 180 to 540 minutes. Residence time in the upper heat transfer zone: Preferably 30 to 360 minutes, more preferably 60 to 180 minutes. For the gase- ous feed stream: Cumulative mole fraction of nitrogen, hydrogen, water vapor, and carbon dioxide: 90% to 100%. Cumulative mole fraction of organic compounds: preferably 10% to 0%, preferably 5% to 0%, and particularly 3% to 0%. Hydrogen to nitrogen ratio: Preferably 0:100 to 100:0, more preferably 10:90 to 100:0, and particularly 20:80 to 100:0. For pre-treatment of biochar, the indicated settings are as follows: Temperature: Preferably 600°C to 1500°C, more preferably 700°C to 1400°C, and especially 800°C to 1300°C. In view of a moving bed reactor: Residence time in the reaction zone: Preferably 90 to 1080 minutes, more preferably 180 to 540 minutes. Residence time in the upper heat transfer zone: Preferably 30 to 360 minutes, more preferably 60 to 180 minutes. For the gaseous feed stream: Cumulative mole fraction of nitrogen, hydrogen, water vapor, and carbon dioxide: Preferably 10% to 90%, more pref- erably 20% to 80%, and particularly 30% to 70%. Cumulative mole fraction of organic compounds: preferably 10% to 90%, more preferably 20% to 80%, and particularly 30% to 70%. Hydrogen to nitrogen ratio: preferably 0:100 to 100:0, more preferably 10:90 to 100:0, and particularly 20:80 to 100:0. During said treatment, the carbon deposition rate of the or 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.-%. 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 Carbon deposition rate [molC / s]Molar flow [molC / s]Conversion rate [-]Carbon deposition rate [g / s]Molar mass [g / mol]Carbon deposition [g / g]Carbon mass increase [g]Carbon mass [g]Carbon deposition rate in [g / g*s]Time unit [s]Carbon deposition rate (per reference time unit) [-] or in [wt.%] 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: 1 Considering the mass [g,C / s]:2The CH4 conversion rate is 3 The carbon deposition in [g / g] is defined as: 4 The carbon deposition rate in [g / (g*s)] follows from the initial mass and the carbon deposition rate in [mol,C / s]: 5 The total increase in carbon mass 6 Considering the reactor volume and tion rate per reference time unit in [-]: 7 The carbon deposition rate per reference time unit can also be expressed in [wt.%] as follows: 8 The reactor specific reference residence time is defined as follows: • Batch / Fixed bed: = total pyrolysis time • Moving bed: 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 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: 9 • Using a reference volume which contains the particle mass to determine the bulk density: 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 deposited 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 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 circula- tion 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. During said treatment, the conversion rate of the cracking or 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 hydro- carbons 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 carrier 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 ash content is higher than 1 wt.-%, preferably higher than 2 wt.-%, preferably higher than 3 wt.-%, preferably higher than 4 wt.-%, pref- erably higher than 5 wt.-%, pretreatment is preferred. Said pretreatment can preferably end, if no or a non- significant amount (< 0.05 vol.-%) of oxygen containing site product, like water, CO, CO2 are present in the hydrogen containing stream, then the production mode of the cracking / pyrolysis process can preferably be started. 3. Adjusting the process conditions of the pyrolysis conditions, especially the deposition rate, start with 1 wt.-% deposition and slowly increasing the deposition rates as the operation time increases Accordingly, the said process includes at least two modes or alternates between two operational modes: 1. Pre-treatment / Passivation 2. Production Production Mode The pre-treated carrier material is suitable for continuous pyrolysis / cracking production mode operation for periods ranging from 10 to 720 days, preferably 20 to 540 days, and particularly 30 to 360 days. 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 acetylene coke, calcined petcoke (CPC), green coke, anode butts, bio char, recycled or recovered carbon black (from polymer recycling via pyrolysis), black mass (battery recycling) or the pyrolytic carbon obtained in a methane pyrolysis itself. The carbon content is preferably in the range of 70 to 99.99 wt.%, more preferably 70 to 99.95 wt.%, even more preferably 70 to 99 wt.%, even more preferably 90 wt.% to 99.95 wt.%, even more preferably 90 wt.-% to 99.9 wt.-%, even 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 clorine 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.%. The BET surface area of the substrate is preferably between 0.1 and 100 m2 / g, preferably 0.1 and 50 m2 / g, in par- ticular 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. Methane Pyrolysis in the production mode Preferably, a methane pyrolysis is conducted in the production mode. The methane pyrolysis is conducted in a mov- ing, fluidized or fixed bed reactor, preferably at temperatures ranging from 500 to 2000°C, preferably ranging from 1000 to 1600°C, even more preferably ranging from to 1500°C, and at pressures ranging from 1 to 50 bar, preferably from 1 to 30 bar, even more preferably 3 to 20 bar, particularly 5 to 15 bar. The methane pyrolysis process can be heated in different ways known to the persons skilled in the art: via plasma, microwave, heated carrier gas, resistance heating, induction, liquid metal processes or autothermal. Preferably the methane pyrolysis process is heated electrically, even more preferably by resistive heating (Joule heating) of the substrate material as described for example in US 2982622, WO 2019 / 145279 and WO 2020 / 200522. The conversion rate is preferably 10 to 90 %, preferably 25 to 85 %, more preferably 30 to 80 %, even more prefera- bly 50 to 80 % (based on the hydrocarbons in the feed stream, see equation 3). During said production mode, the carbon deposition rate of the cracking or pyrolysis process, is preferably above 2 wt.-%, more preferably below 5 wt.-%. The deposition rate is preferably above 2 to 20 wt.-%, more preferably 3 to 15 wt.-%, more preferably 4 to 12 wt.-%, even more preferably 4 to 10 wt.-%, even more preferably 4 to 8 wt.-%. The definition of the carbon deposition rate is shown below. The deposition rate is preferably adjusted by diluting the hydrocarbon feed with hydrogen to a volume ratio of prefer- ably H2 / C1+ 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. Preferred Process Conditions: Moving Bed Preferably the 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, pref- erably 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. 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 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 directly heat the solid substrates in the reaction zone by generating an electric current in the solid substrates between a pair of first and second electrodes such that, heating by transferring heat from the solid substrates to methane, - methane in the reaction zone can be heated to temperature to produce hydrogen and granular py- rolytic carbon, - and wherein the reactor interior also comprises a first heat integration zone in which heat from hydrogen pro- duced 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. 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 or- der to heat methane in the reaction zone, wherein methane is decomposed to hydrogen and granular pyrolytic 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 and not converted hydrocarbons are 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. The said moving bed reactor has several advantageous compared to other reactor types. - Heat integration enables a high efficiency since and solid are leaving the reactor at temperatures between 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 contin- uous 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 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 prefer- ably form 60 vol% to 100 vol % o Due to the relative motion of the particles in a fluidized bed, carbon deposition rates from the pyrolyzed gas on the solid granule per pass through the reactor are preferred above 10 wt-% and more preferred above 20 wt-%. 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. Interconnected Moving Bed Pyrolysis Reactor and Pre-treatment Reactor. Preferably the pre-treatment is conducted in parallel to the pyrolysis production mode. The pre-treated carbon is introduced into the solids feed of the pyrolysis reactor in batch or in a quasi-continuous mode, preferably in a quasi- continuous mode. The ratio of the effective mass flow rate of the pre-treated carrier to the solid feed rate to the pyrol- ysis reactor is from 0.05% to 10%, preferably from 0.1% to 5%, particularly preferably from 0.3% to 3%. The pre- treatment process may be conducted either in batch mode or in a continuous mode, preferably in a continuous mo- deIn batch mode. Pre-treatment is performed in either a fixed-bed reactor or a fluidized-bed reactor. A typical pre- treatment campaign lasts between 6 and 48 hours, preferably between 12 and 24 hours. The ratio of the reaction volume of a fixed-bed reactor to that of the pyrolysis reactor is between 3% and 30%, preferably between 4% and 25%. The ratio of the reaction volume of a fluidized-bed reactor to that of the pyrolysis reactor is between 10% and 100%, preferably between 20% and 75%. Preferably, in continuous mode said pretreatment is conducted in a fluidized bed or in a moving bed reactor and said cracking or pyrolysis process of hydrocarbons in the production mode is conducted in a moving bed. The ratio of the reaction volume of a moving-bed reactor for said pretreatment to that of the pyrolysis reactor for the production mode is between 0.1% and 5%, preferably between 0.3% and 3%. The ratio of the reaction volume of a fluidized-bed reactorfor said pretreatment to that of the pyrolysis reactor for the production mode is between 0.5% and 20%, preferably between 1% and 10%. Preferably, after the pretreatment, the pretreated solid material is withdrawn from the fluidized bed or moving bed reactor of the pretreatment and introduced into the moving bed reactor for the production mode. Advantages of the present invention In the present invention, materials are pretreated and thus prepared for the usage as carrier in the cracking of hydro- carbons. By the pretreating process, the formation of carbon filaments in the cracking process is significantly reduced or even prevented. The formation of filaments is associated with a higher risk of agglomeration or a reduced level of agglomeration of the carrier particles in the cracking process. Hence, by reducing or preventing the filament for- mation, the risk of agglomeration of particles is strongly reduced, which allows the deposition of higher amounts of carbon per batch / cycle without reaching a critical level of agglomeration / blockage of the moving beds solid flow. The amount of deposited carbon determines the production rate in methane pyrolysis and is thus a crucial parameter of the overall economics of a commercial methane pyrolysis process. In a fixed bed reactor, the amount of deposited carbon directly limits the maximum production capacity per batch, while it determines the continuous carbon produc- tion rate for a given carrier flow rate in a moving bed reactor or fluidized bed reactor. Hence, the increase in the achievable carbon deposition without reaching a critical level of agglomeration directly increases the production ca- pacity with all associated advantages regarding the capital expenditures and the operational expenditures of the process. Furthermore, by the pretreating process also initially not preferred materials can be prepared for the usage as carrier material in methane pyrolysis. For example, carbon-based materials with increased metal contents and / or increased oxygen contents (for example bio-based carbon, low grade CPC, anode butts, green coke etc.) can be pretreated and thus be made available for the usage as carrier materials in cracking processes of hydrocarbons. This way low-cost alternatives to high purity carbon carriers can be upcycled for cracking processes of hydrocarbons and production loops in customer markets producing low grade carbons as unwanted side products can be closed, hav- ing advantages both regarding commercial as well as sustainability aspects. Surprisingly, the deposition of a layer of pyrolysis carbon of 0.5 g / 100g carrier (0.5 wt.-%) proves an inertization of the surface in such a way that agglomerate formation is avoided in the subsequent pyrolysis operation. In contrast, a layer with this function cannot be formed if a larger amount of pyrolysis carbon is deposited directly on the untreated surface of the carrier. Figure Figure 1 shows a moving bed reactor (1a), a fixed bed reactor (1b), cited in [1], and a fluidized bed reactor (1c), cited in [2] Figure 2: SEM pictures of carbon with pretreatment (Experiment 2, (b) right side) and a carbon bed without pretreat- ment (Experiment 1, (a) left side) after pyrolysis with a temporal temperature ramp. On the pretreated carbon bed, no filaments were formed. Figure 3: SEM pictures of the pyrolysis carbon surfaces obtained in experiments in a moving bed reactor. Left without H2 Pre-treatment (experiment 3), right with H2 pre-treatment (experiment 4). Figure 4 SEM pictures of the pyrolysis carbon surfaces obtained in experiment 5. The sample was pretreated with N2, no filaments were formed.

[0002] Working examples: 1. Pretreatment: 1.1 Hydrogen 1.1.1 Natural gas cracking in a fixed bed reactor for a hydrogen pretreated and not pretreated carbon bed (Experi- ments 1 and 2) Pyrolysis of natural gas was carried out in two experiments in a fixed bed reactor. The same process conditions and feeds were applied for the shown examples 1 and 2 during the pyrolysis step. The only difference between the two examples was the pre-treatment of the solid carbon granule (CPC) prior the pyrolysis in experiment 2. The pretreatment was started by heating up the reactor in 100 % N2 from room temperature to 1300°C at a heating rate of 200 °C / h. After reaching 1300 °C the pretreatment in 100 % H2 was started and carried out for 4 h. For a fast start-up on the next day: The carbon was cooled down in a 100% N2 atmosphere with a temperature ramp of 200 °C / h to 600 °C and held at 600 °C over night (20.5 hours). Afterwards, the same pyrolysis step was carried out as in experiment 1. In the pyrolysis step a mixture of 20 % natural gas in hydrogen was used as feed mixture at a reactor pressure of 1 bara. A temperature ramp was applied during pyrolysis: 1. Starting temperature 600 °C, 2. Increase in temperature from 600 °C up to 1250 °C at a rate of 150 °C / h, 3.1 h operation at 1250 °C, 4. Cooling down to 1000 °C at a rate of 200 °C / h, afterwards the flow of reactants was turned off. The utilized reactor was a fixed bed reactor filled over a total height of ~560 mm with solid carbon granule (CPC) in a ceramic tube with an inner diameter of 50 mm. The resulting carbon beds of both experiments were analyzed via SEM. In Figure 2 the resulting SEM pictures of the pretreated carbon bed of experiment 2 are compared with SEM pictures of the carbon bed without a thermal pre- treatment of experiment 1. On the SEM pictures of the pretreated carbon bed no filament formation was detected, while numerous filaments are visible in the not pre-treated particles of experiment 1. Hence, filament formation was successfully prevented by the thermal pretreatment. In Table 1 a qualitative description of the resulting agglomeration levels of experiments 1 and 2 along the fixed bed is listed. The pretreated carbon bed of experiments 2 was significantly less agglomerated than the non-pretreated bed of experiment 1 showing the strong influence of filament formation on the level of agglomeration. Table 1: Agglomeration levels for natural gas pyrolysis in a fixed bed reactor using a carbon bed without pretreatment and a carbon bed pretreated with hydrogen Position of the carrier* Level of agglomeration** Without (experiment 1) With pretreatment (experiment 2) 1 0 0 2 0 0 3 2 1 4 3 1 5 3 2 6 3 1 7 3 1 8 3 1 9 3 1 10 3 1 *Position 1 is the closest to the feed inlet. The positions are distributed at equal distances of approx.56 mm over the reactor height of 560 mm. **The level of agglomeration describes qualitatively how hard the particles are agglomerated after the experiment. It is described by how easily the particles can be extracted from the fixed bed and the state of the particles. A brief description of the scale: 0. Loose: No agglomeration, particles can be very easily extracted (particles flow out without applying additional force, when reactor tube is tilted). 1.Gently: Low level of agglomeration, particles start sticking to each other, but agglomerates break at impact of low forces (for example manual hitting with a pipe), particles can still be easily extracted, but no complete free flow. 2. Markedly: Particles form agglomerates that require a medium impact to be broken up, extraction of particles is only possible after applying force to break the agglomerates. Agglomerates still break into single particles during extrac- tion. Blocking of a moving bed starts to become likely, depending on the scale and existing forces inside the reactor. 3. Firmly: Particles are firmly agglomerated. Regular application of stronger forces is required to break the agglomer- ation and allow to extract particles from the fixed bed. This results in increasing occurrence of breaking of particles (high dust content and particles smaller than the target PSD). Agglomerates are still conserved and are not broken up into single particles upon extraction from the fixed bed. At this level of agglomeration, it is considered as highly unlikely, that the solid flow of a moving bed would not be seriously disturbed, and the reactor be blocked. 4. Very Firmly: Strong agglomerates are formed that need to be “mined” out of the reactor. Large, firm agglomerates are broken out of the fixed bed, mixed with broken particles and carbon dust. SEM pictures of carbon with pretreatment (Experiment 2, (b) right side) and a carbon bed without pretreatment (Ex- periment 1, (a) left side) after pyrolysis with a temporal temperature ramp. On the pretreated carbon bed, no fila- ments were formed. 1.1.2 Long-time experiment and comparative examples in a moving bed reactor (Experiments 3 and 4) Pyrolysis of natural gas to H2 and solid carbon was carried out in a moving bed reactor. The same process condi- tions and feeds were applied for the shown Experiments 3 and 4 during the pyrolysis. The only difference was the pretreatment of the solid granule with 100% H2 gas feed under the shown moving bed conditions for Experiment 4 prior the pyrolysis. Figure 3 shows photographs taken by a Scanning electron microscope (SEM). The left shows the pyrolysis carbon surface of Experiment 3, the right pyrolysis carbon surface of Experiment 4. A significant amount of carbon filaments can be seen in for Experiment 3. Applying pretreatment with hydrogen prohibits the formation of carbon filaments (example 2 right picture). In Experiment 3 serious blockage of the moving bed was observed after 72 hours of natural gas pyrolysis, stopping the run. The blocking was observed for material that was passed through the moving bed reactor for a 2ndcycle of natural gas pyrolysis. In Experiment 4 no serious blockage of the moving bed was observed and the operation of the reactor was stopped after a total of 1340 hours of natural gas pyrolysis. During the operation time the material was passed through moving bed reactor for a total of 24 cycles of natural gas pyrolysis. The resulting carbon beds of both experiments were analyzed via SEM. In Figure 3 the resulting SEM pictures of the pretreated carbon bed of experiment 4 are compared with SEM pictures of the carbon bed without a thermal pre- treatment of experiment 3. On the SEM pictures of the pretreated carbon bed of experiment 4 less filament formation was detected, while numerous and especially thin filaments are visible in the not pre-treated particles of experiment 3. Hence, filament formation was successfully prevented by the thermal pretreatment. Table 2: Process conditions natural gas pyrolysis in a moving bed reactor Example 3 Example 4 Gas-Feed 20 vol% Natural Gas 20 vol% Natural Gas 80 vol% H2 80 vol% H2 Max Temperature [°C] 1250 1250 Solid granule CPC CPC Pretreatment H2 No Yes Operating pressure [bara] 2.4 2.4 Operation time [h] 72 1340 Passage of the solid material 2 24 (moving bed) through the reactor “end of experiment” Agglomeration End of campaign 1.2 Nitrogen (Experiment 5) Analogous to experiment 2, another pretreatment experiment was carried out but with 100 % N2 for the entire pre- treatment protocol in experiment 5. The following pretreatment protocol was used: The pretreatment was started by heating up the reactor in 100 % N2 from room temperature to 1300°C at a heating rate of 200 °C / h. Pretreatment at 1300 °C was carried out for 5 h. For a fast start-up on the next day: The carbon was cooled down in a 100% N2 atmosphere with a temperature ramp of 200 °C / h to 600 °C and held at 600 °C over night. The same pyrolysis procedure was used in experiment 5 as in experiment 1 and 2 was used. In Figure 4 SEM pictures of the N2 pretreated carbon bed of experiment 5 shown. No filaments are visible.

Claims

Claims 1. Process for minimizing filament formation or agglomeration of carbon in cracking or pyrolysis process of hy- drocarbons that includes a fixed, fluidized or moving bed, wherein the bed comprising solid material is pre- treated and passivated with an atmosphere of hydrogen and / or inert gases before starting the production mode of the cracking or pyrolysis process of hydrocarbons or the bed is treated temporarily between two pro- duction process mode steps of said cracking or pyrolyzing of hydrocarbons, wherein the time and temperature of said treatment is characterized by the formula T (min * °C) = time (min) multiplied by temperature (°C) and T is at least 10000 min * °C and wherein the temperature is at least 500°C, wherein during said treatment the carbon deposition rate of the cracking or pyrolysis process, if any, is below 2 wt.-%, and wherein the atmos- phere of said treatment contains 70 to 100 Vol.-%, related to the total atmosphere used for the treatment, of hydrogen and / or inert gases, and 30 to 0 Vol.-% of gaseous hydrocarbons.

2. Process according to claim 1, wherein a carbon-containing substrate is used as solid material having a carbon content of 70 to 99.99 wt.-%.

3. Process according to claim 2, wherein calcined petcoke, acetylene coke, green coke, anode butts, bio char or pyrolytic carbon is used as carbon-containing substrate.

4. Process according to any of claims 1 to 3, wherein the particle size of the substrate is in the range of 0.1 to 10 mm.

5. Process according to any of claims 1 to 4, wherein T is at least 100000 min * °C.

6. Process according to any of claims 1 to 5, wherein T is in the range of 100000 to 1500000 min * °C.

7. Process according to any of claims 1 to 6, wherein the time of said treatment is in the range of 60 min to 12 hours.

8. Process according to any of claims 1 to 7, wherein the temperature of said treatment is in the range of 1000°C to 1500°C.

9. Process according to any of claims 1 to 8, wherein during said treatment the conversion rate of the cracking or pyrolysis process, if any, is below 50 %.

10. Process according to any of claims 1 to 9, the atmosphere of said treatment contains 100 Vol.-%, re- lated to the total atmosphere used for the treatment, of hydrogen and / or inert gases like nitrogen, argon.

11. Process according to any of claims 1 to 10, wherein after pre- or temporarily treatment the production mode of the pyrolysis process starts with the following pyrolysis conditions: start with 1 wt.-% carbon deposition rate and increase the carbon deposition rate as the operation time increases.

12. Process according to any of claims 1 to 11, wherein during said treatment, the hydrocarbons contained in the treatment atmosphere have a volume ratio of C1 / C2+ of 20 to 50.

13. Process according to any of claims 1 to 12, wherein during the production mode, the carbon deposition rate is above 2 wt.-%.

14. Process according to any of claims 1 to 13, wherein during the production mode, the carbon deposition rate is above 5 wt.-%.

15. Process according to any of claims 1 to 14, wherein the pyrolysis process is a methane pyrolysis and said me- thane pyrolysis is conducted in a moving bed reactor at temperatures ranging from 500 to 1800°C and at pressures ranging from 1 to 30 bar, wherein the bed contains as substrates carbon-containing material and wherein the substrate is guided in countercurrent to the methane.

16. Process according to any of claims 1 to 15, wherein said treatment is conducted in a fluidized bed or a moving bed and said cracking or pyrolysis process is conducted in a moving bed.

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