EP4058403A1

EP4058403A1 - Method and device for producing hydrogen and pyrolytic carbon from hydrocarbons

Info

Publication number: EP4058403A1
Application number: EP20807329.6A
Authority: EP
Inventors: Nicolai Antweiler; Karsten BÜKER
Original assignee: ThyssenKrupp AG; ThyssenKrupp Industrial Solutions AG
Current assignee: ThyssenKrupp AG; ThyssenKrupp Industrial Solutions AG
Priority date: 2019-11-13
Filing date: 2020-11-12
Publication date: 2022-09-21
Also published as: US20230025624A1; CN114630807A; WO2021094464A1; CN114630807B; DE102019130600A1

Abstract

The invention relates to a method for producing hydrogen and pyrolytic carbon from hydrocarbons, wherein hydrocarbons are reacted in a reactor at temperatures of 1000°C or more to form hydrogen and carbon, and wherein the reactor has two electrodes spaced apart from one another in the flow direction of the hydrocarbons, wherein an inert gas component is supplied over the entire reactor cross section in the region of the reactor between the electrodes, and wherein the reactor contains carbon particles in the region between the two electrodes. By introducing an inert gas component over the entire reactor cross section, a deposition of carbon in this region of the reactor internal wall is prevented, such that the formation of reactivity bridges on the reactor internal wall is effectively suppressed. The invention also relates to a corresponding device which is designed for carrying out the proposed method.

Description

Process and device for the production of hydrogen and pyrolysis carbon from hydrocarbons

description

Field of the invention

The invention is in the field of the pyrolytic decomposition of hydrocarbons and in particular of methane to hydrogen and pyrolytic carbon and relates in particular to a new method for a corresponding conversion in which the reactor has two electrodes spaced apart in the direction of flow of the hydrocarbons and wherein in the area of the reactor an inert gas component is fed in between the electrodes over the entire reactor cross-section. The invention also relates to a device for carrying out a corresponding method.

State of the art

In the near to medium term future, hydrogen production will continue to be based on fossil fuels, primarily natural gas (NG). On the other hand, conventional hydrogen production processes are one of the main sources of anthropogenic _{CO 2} emissions into the atmosphere.

In principle, hydrogen can be obtained from hydrocarbon fuels through oxidative and non-oxidative conversion processes. Oxidative transformations involve the reaction of hydrocarbons with Oxidizing agents such as water, oxygen or combinations of water and oxygen (steam reforming, partial oxidation and autothermal reformation processes). As a first step, a mixture of hydrogen and carbon monoxide (synthesis gas) is formed in these processes, from which the hydrogen is separated off by gas conditioning (water gas shift reaction) and preferably oxidation reactions and CO ₂ removal stages. The total C0 ₂ emissions from these processes reach up to 0.5-0.6 m ³ per m ^{3 of} hydrogen produced.

Non-oxidative processes involve the thermal decomposition (or dissociation, pyrolysis, cracking) of hydrocarbons into hydrogen and carbon. The thermal decomposition of natural gas has been used for several decades as a means of producing carbon black, with hydrogen being an additional product of value that occurs in the process. In this process, hydrocarbon vapor is decomposed into hydrogen and soot particles at a temperature of about 1400 ° C. over a preheated contact. The process was carried out, for example, as a semi-continuous (cyclic) process using two tandem reactors. No. 2,926,073 describes an improved device for producing soot and hydrogen from hydrocarbons by a continuous thermal decomposition process. The Kvaerner Company from Norway has developed a methane decomposition process that generates hydrogen and soot at high temperatures (CB&H process, disclosed in Proc. 12th World Hydrogen Energy Conference, Buenos Aires 697, 1998). The advantages of the plasma-chemical processes used in this process are high thermal efficiency (> 90%) and the purity of hydrogen (98% by volume). However, the high energy requirement is a disadvantage. Steinberg et al. have in Int. J. Hydrogen Energy, 24, 771, 1999 proposed a methane decomposition reactor which consists of a molten metal bath. In this reactor, methane bubbles are passed through a molten tin or copper bath at high temperatures (900 ° C and more). The advantages of this system consist in an efficient heat transfer to the methane gas flow and an easy separability of the carbon from the liquid metal surface due to the density difference.

A high temperature regenerative gas heater for hydrogen and carbon production was developed by Spilrain et al. in Int. J. Hydrogen Energy, 24, 613, 1999. In this process, the thermal decomposition of natural gas was carried out in the presence of a carrier gas (N ₂ or H ₂ ) which was preheated in the matrix of a regenerative gas heater to a temperature of 1627 ° C to 1727 ° C.

A problem with these previously described processes is the very high temperature required for the methane cracking. There have therefore been numerous attempts to lower the temperature required for the thermal decomposition of methane by using catalysts. Transition metals in particular have proven to be very active as catalysts for the methane decomposition reaction. One problem, however, is catalyst deactivation due to carbon deposits on the catalyst surface.

To solve this problem, in most cases, surface carbon deposits have been burned with air to regenerate the original catalytic activity. However, this has the disadvantage that all of the carbon is converted to C0 ₂ and hydrogen is obtained as the only usable reaction product. For example, Callahan in Proc. 26th Power Sources Symp. Red Bank, MJ 181, 1974, discloses a catalytic reactor (fuel conditioner) designed to catalytically convert methane and other hydrocarbons to hydrogen for fuel cell applications. A stream of gaseous fuel is introduced into one of two reactor beds, where the hydrocarbon decomposition to hydrogen takes place at a temperature of 870-980 ° C and the carbon is deposited on a nickel catalyst. At the same time, air is introduced into the second reactor, where the catalyst is regenerated by burning off the carbon deposited on the catalyst surface. The flow of fuel and air was reversed for another cycle of decomposition / regeneration. The process described does not require any water gas shift or gas separation stages, which is a significant advantage. However, due to the cyclic nature of the process, hydrogen becomes contaminated with carbon oxides. The process also has the disadvantage that no carbon by-product is formed in the process.

The US 3,284,161 describes a process for the continuous production of hydrogen by catalytic decomposition of gaseous Hydrocarbon streams. The methane decomposition was carried out in a catalytic fluidized bed reactor in the temperature range from 815 to 1093 ° C. Nickel, iron and cobalt catalysts (preferably Ni / Al ₂ 0 ₃ ) were used in this process. The carbon contaminated catalyst was continuously removed from the reactor and placed in a regeneration area where the carbon was burned off. The regenerated catalyst was then recycled to the reactor.

No. 5,650,132 describes a method for producing hydrogen from methane and other hydrocarbons by bringing it into contact with fine particles of a carbon-based material that is produced by arc discharge between carbon electrodes and that has an external surface area of at least 1 m ² / g. The carbon-based material additionally included soot obtained from the thermal decomposition of various organic compounds or the combustion of fuels, carbon nanotubes, activated carbon, fullerenes C60 or C70, and finely divided diamond. The optimal conditions for methane conversion include: methane dilution with an inert gas (preferably to a methane concentration of 0.8 to 5% by volume), a temperature range of 400 to 1200 ° C and residence times of about 50 seconds. An increase in the methane concentration in the starting material from 1.8 to 8% by volume (at 950 ° C). resulted in a drastic reduction in methane conversion from 64.6 to only 9.7%. It is also mentioned that the catalytic activity of the carbon catalysts gradually decreases during hydrocarbon pyrolysis. In order to extend the life of the catalyst, it has been proposed _{to supply oxidizing gases such as H 2} O or C0 ₂ to the pyrolysis zone. However, this would have the disadvantage that the hydrogen is contaminated with carbon oxides, which makes an additional cleaning step necessary. It has also been suggested that spent catalyst be incinerated, but this would be very inconvenient due to the high cost of the carbon materials used in this process.

US 2007/111051 describes a process for the C0 ₂ -free production of hydrogen and carbon by thermocatalytic decomposition of hydrocarbon fuels over carbon-based catalysts in the absence of air and water. As a catalyst in this case for example activated carbon "Darco ^® -KB-B" is used, which has a surface area of 1,500 m ² / g, a total pore volume of 1.8 ml / g and a particle size of 15 μm. The actual decomposition of the hydrocarbon feedstock occurs in the context of this process at temperatures in the range of about 850 to 1000 ° C.

In conventional reactors for the pyrolytic decomposition of methane gas into carbon and hydrogen, as can already be seen from the above, the resulting carbon in particular represents a major problem. To solve this problem, a project at TU Dortmund University, Faculty of Biological and Chemical Engineering, Chair for chemical process engineering under the direction of Prof. DWAgar (available at dechema.de/dechema_media/2942_Schlussbericht-p-4820.pdf) proposed a process in which methane is heated from top to bottom in a reactor room that is heated to temperatures of around 1100 ° was, is directed. As a result of this reaction, soot particles that are produced can fall down during the process and can be discharged there with other gas components, such as the hydrogen gas and unconverted residual methane gas. To prevent the carbon from settling on the edge of the reactor vessel, the actual reactor space is formed by a cylindrical porous ceramic matrix through which an inert gas, for example in the form of nitrogen (N ₂ ) gas, is introduced into the reactor space.

As part of the process developed by the Fraunhofer Institute for Ceramic Technologies, a reactor is completely surrounded by a heating medium in order to provide the energy required for the process. However, such a structure is difficult to implement, particularly in the case of larger reactors, and requires significant amounts of energy. It is easier to heat the reactor space by means of electrical resistance elements that are installed in the reactor space itself. For this purpose, one or more pairs of electrodes can be arranged in the reactor, via which the reaction gases are heated by resistance, for example by having a conductive material such as carbon particles between the electrodes. With such a reactor design, however, there is the problem that the inner wall of the reactor in the reaction zone has temperatures above the pyrolysis temperature of methane / lower hydrocarbons. This leads to this Pyrolize compounds on the reactor wall too, so that a pyrolysis carbon layer is formed on the inner wall of the reactor. The conductivity properties of the carbon layer can lead to an increasing current flow from one electrode via the pyrolytic carbon layer on the wall to the other electrode, which in extreme cases can lead to a failure of the heating if, as a result, no more current flows through the carbon bed.

There is therefore a need for a process management of appropriately designed reactors with which the formation of a carbon conductivity bridge on the reactor wall is prevented. The present invention addresses this need.

Description of the invention

The invention therefore relates to a process for the production of hydrogen and pyrolysis carbon from hydrocarbons, the hydrocarbons being converted to hydrogen and carbon in a reactor at temperatures of 1000 ° C or more, and the reactor having two electrodes spaced apart in the direction of flow of the hydrocarbons , characterized in that in the area of the reactor between the electrodes an inert gas component is supplied over the entire reactor cross-section and that the reactor contains carbon particles in the area between the electrodes. In other words, within the scope of the process according to the invention, an inert gas component, such as nitrogen, is fed in over the entire reactor cross-section.

In the context of the present invention, “inert gas component” denotes a gas or mixture of gases that is chemically inert with respect to the hydrocarbons in the reactor and does not react with them. This does not rule out that the inert gas component contains or consists of constituents that are inert with respect to the products generated in the reaction, in particular with respect to the carbon generated. For example, hydrogen is a gas that can form methane with carbon under suitable conditions, which can be used within the scope of the invention to break down carbon deposits on the walls of the reactor. The statement that the inert gas component is fed into the reactor "over the entire reactor cross-section" is not to be understood to mean that an inert gas component is to be introduced in the entire area between the two electrodes. The inert gas component is preferably introduced between the electrodes only in a partial area of the reactor wall. This can be done, for example, by one or more feed devices. The inert gas component is preferably introduced into the reactor space via one or more feed devices which are arranged on the reactor wall orthogonally to the direction of flow of the hydrocarbons introduced into the reactor.

The carbon particles can be stationary in the area of the reactor between the two electrodes, but it is also possible that the carbon particles are in motion in this area. In the context of the present invention, it is preferred if the carbon particles are passed through the reactor against the direction of flow of the hydrocarbons, since in this way the formation of conductivity bridges (due to the adhesion of carbon formed in the reaction) and thus a non-uniform temperature profile in the reactor can be largely suppressed .

The hydrocarbons to be included in the process according to the invention are not subject to any relevant restrictions as long as the release of hydrogen and the formation of carbon in the temperature range above 1000 ° C. are possible. Suitable hydrocarbons are, for example, gaseous or liquid hydrocarbons such as methane, propane, gasoline, diesel, residual oil or crude oil at normal temperature and normal pressure. Preferred hydrocarbons in the context of the present invention are gaseous hydrocarbons such as methane and propane, of which methane is particularly preferred. The conversion of these hydrocarbons takes place according to the reaction equations. where n is greater than 1 and m is equal to or less than (2n + 2). Both reactions are endothermic. In the context of the process according to the invention, the inert gas component is preferably an inert gas, such as nitrogen or argon, or a gas which is inert towards the hydrocarbons, such as the hydrogen gas generated in the reaction. The “inert gas” should essentially, ie preferably 80% by volume, more preferably at least 90% by volume, and even more preferably at least 95% by volume, consist of an inert gas; If the process is carried out appropriately, small proportions of non-inert gases, such as methane, can be tolerated. In principle, however, in these cases the temperature of the inert gas introduced should be selected below the decomposition temperature of methane gas in order to prevent soot formation in the feed for the inert gas component. Both the inert gas component and the hydrocarbons should be free of oxidizing or oxidized constituents.

The carbon particles used can expediently be those which, in the range above 1000 ° C., promote pyrolytic decomposition of the hydrocarbons and are electrically conductive.

Particularly suitable carbon particles within the scope of the invention include the products commercially available as DARCO® KB-B (from Norit Americas Inc.), Black Pearls2000 (from CABOT Corp.) or XC-72 (from CABOT Corp.). In principle, however, any material made of carbon can be used, such as calcined petroleum coke, coking coal or the pyrolysis carbon generated in the process.

In the context of the invention, it is generally sufficient if the process is operated in the starting phase with carbon particles that have been produced separately for this purpose. Subsequently, part of the pyrolysis carbon generated in the course of the process, either alone or in a mixture with the separately produced carbon particles, can be used as carbon particles. For reasons of cost, preference is given to predominantly using pyrolysis carbon and particularly preferably using pyrolysis carbon exclusively from the process after the start phase, ie after sufficient pyrolysis carbon has been generated in the reactor to operate the process with it. The term “predominantly” here denotes a proportion of at least 60% by weight, preferably at least 70% by weight, more preferably at least 80% by weight, and even more preferably at least 90% by weight, based on the total amount of carbon particles.

For the process according to the invention, it is also advantageous if the reaction zone in the reactor space is arranged vertically and the hydrocarbons pass through the reaction zone from bottom to top and the carbon particles pass through the reaction zone from top to bottom. This procedure ensures, on the one hand, that a temperature transfer between the hydrocarbons fed to the reactor chamber and the carbon particles is made possible. On the other hand, carbon generated from the hydrocarbons is largely deposited on the carbon particles and, in the case of non-static carbon particles, transported with the carbon particles downwards out of the reaction chamber, while the product gas generated in the reactor chamber is discharged from the top of the reactor. This ensures that the resulting product gas is essentially free of carbon formed in the reactor space.

Additionally or alternatively, the process according to the invention is particularly advantageous if the temperature in the reaction zone of the reactor is kept in the range from 1000 ° C to 1900 ° C, preferably in the range from 1200 ° C to 1500 ° C.

As already indicated above, it is expedient if the inert gas component has a temperature which is lower than the temperature required for the decomposition of hydrocarbons to carbon and hydrogen. Appropriate process management can ensure in the area where the inert gas component is fed into the reactor space that the reactor wall is colder in this area than in the rest of the reactor, so that soot formation is suppressed in the vicinity of the inlet of the inert gas component. In addition, a cooler inert gas ensures that no carbon forms in the supply lines for the inert gas to the reactor, which could clog the lines. In a preferred embodiment, the inert gas component fed in has a temperature of less than 1000.degree. C., preferably less than 900.degree. C. and particularly preferably in the range from 200 to 800.degree. As also already mentioned above, hydrogen is an inert gas, for example in relation to the pyrolysis reaction of methane to hydrogen and carbon, and can be used as an inert gas component in the context of the present invention. In a preferred embodiment, the process according to the invention is therefore designed such that part of the product gas generated in the process, preferably 5 to 30% by volume and in particular 10 to 25% by volume, is fed to the reactor as an inert gas component.

The hydrocarbons, especially in the form of methane, should expediently be fed into the reactor at a flow rate which ensures an extensive (i.e. at least 20%) to essentially complete (i.e. at least 70%) conversion of the hydrocarbons to hydrogen and carbon. A flow rate in the range from 0.001 m / s to 10 m / s, preferably 0.01 m / s to 1 m / s, can be specified here as a suitable flow rate.

Furthermore, the process according to the invention is particularly advantageous if the inert gas component is fed into the reactor at a flow rate in the range from 0.001 m / s to 100 m / s, preferably 0.1 m / s to 10 m / s.

For the carbon particles used within the scope of the process according to the invention, a particularly favorable process procedure is established when they are fed into the at a flow rate in the range from 0.5 m / h to 100 m / h and preferably 1 m / h to 10 m / h Reactor are fed.

Another aspect of the present invention relates to a device for the pyrolytic conversion of hydrocarbons to hydrogen and carbon, comprising a reactor 1 with a reactor chamber, which has two electrodes 2 which are spaced apart in relation to the flow direction of the hydrocarbons and via which the reactor is heated by resistance can, and has a supply device for an inert gas which is attached in the region between the electrodes of the reactor and which extends over the entire cross-section of the reactor. This device is useful with supply lines for starting product (eg methane) and Koh len material particles as Catalytic converter and includes exhausts for carbon particles and product gas.

The feed device is preferably attached orthogonally to the intended direction of flow of hydrocarbons and carbon particles in the reactor. The feed device comprises a distributor for inert gas components which is fluidly connected to the reactor space (i.e. e.g. via a continuous gap which intersects the reactor space, this forms an inlet opening). The reactor cross-section in the device described above is expediently round, in particular circular or oval. There can also be several feed devices for inert gas components in the reactor.

The device can furthermore advantageously be further developed in that the feed device is designed such that the reaction cross-section tapers above and / or below the inlet opening of the inert gas component into the reactor. It is particularly preferred that the reactor cross-section tapers above and below the gas inlet opening. The tapering above the inlet opening 6 ensures exposed abrasion of the pyrolysis layer that is being formed and reduces the probability of carbon particles being located in the area of the inlet of the inert gas. The cross-sectional taper below the inlet opening 7 reduces the dynamic pressure of the feed gas or hydrocarbon gas flow on the inlet opening.

On the other hand, for reasons of structural complexity, it can be expedient if the feed device is designed in such a way that the reactor cross-section in the area between the electrodes with the exception of the inlet opening of the inert gas component from the feed device is uniform, that is, with the exception of this inlet opening in the reactor cross-section in the area there is no tapering or widening between the electrodes. As a result of the inlet opening of the feed device, which is set back in comparison to the reactor wall, the gas velocity is slightly reduced in this area.

If the inert gas introduced radially has a sufficiently low temperature, the radial temperature profile becomes low wall temperatures shifted, which in turn leads to reduced pyrolysis in this area. In order to achieve a uniform distribution of the gas phase volume flow over the reactor cross-section, the height Hl of a gap through which the inert gas component is fed into the reactor, or the pressure loss Dr between the gas pressure PI in the distributor of the feed line and the gas pressure P2 in the reactor, is expedient to set an area which ensures a distribution of the gas component over the entire cross section (ie the pressure in the area PI is greater by Dr than the pressure in the reactor P2). Dr is dependent on the geometry and the conditions in the reactor.

It is also useful if the geometry of the distributor of the inert gas in the feed device is designed so that no carbon particles can enter the distributor geometry and a pyrolysis carbon bridge can form over this due to a longer residence time. For this purpose it is also preferred if the inert gas is introduced into the reactor at an angle of 30 ° to 60 °, preferably about 45 °, counter to the direction of flow of the hydrocarbons.

The product gas formed during the process consists, under favorable conditions, to a substantial extent of hydrogen with only small amounts of methane. The product gas is therefore suitable for partial recycling of the product gas stream as an inert gas in the reactor space.

It is therefore preferred for the device according to the invention that it has a discharge line for product gas 13 formed in the reactor, and that the discharge line has a branch line 14 via which part of the product gas is fed back into the reactor via the feed device for inert gas. Since, as indicated above, the pressure for feeding the inert gas into the reactor space in the area of the feed line must be higher than in the reactor space itself, it is useful if the device in the area of the branch line 14 has a compressor 15 with which the inert Gas is compressed to a higher pressure.

The use of product gas (H ₂ ) as the inert gas has the additional advantage that the product gas stream in the area of the feed line has a temperature which is significantly below the pyrolysis temperature of methane. The im The pressures present in the reactor space (usually in the range from 10 to 15 bar) are therefore in equilibrium for the CH reaction H ₂ + C _stuck on the side of methane. In the area of the distribution cross-section, due to the lower temperature of the gas flow, the equilibrium is also on the methane side, so that the H ₂ -containing gas flow introduced radially leads to methanation of the carbon present or to chemical carbon removal. As a result of the temperature increase in the area above the entry point of the inert gas, the methane formed pyrolyses again to hydrogen and carbon, so that continuous cleaning of the feed areas for the inert gas is possible within the scope of the process by this process management.

Brief description of the drawings

Figure 1 shows a reactor 1 designed according to the invention with two spaced electrodes 2 and a carbon bed 3 extending beyond both electrodes the reactor is conducted. The reactor cross-section is tapered 6.7 below and above the distributor structure 5. As a result, an increased gas velocity is realized in these tapered areas, which reduces the probability of the presence of carbon particles in this area. In the area below the distributor structure for inert gas 7, the tapering also acts as a deflection for gas flowing through. A pyrolysis carbon layer 8 forms on the inner wall of the reactor in the course of the process.

FIG. 2 shows different variants of the feed line for inert gas into the reactor space, variants A and B being designed with tapering of the reactor cross-section in the area above and below the feed line for the inert gas, while in variant C a feed line is designed in such a way that that the reactor cross-section in the area between the electrodes with the exception of the outlet for inert gas from the feed device is uniform.

FIG. 3 shows a gas distributor construction according to the invention, where H 1 is the gap height through which the gas from the distributor space into the reactor space flows in, indicates. PI denotes the manifold pressure, P2 the reactor pressure and Dr the pressure loss between manifold pressure and reactor pressure.

FIG. 4 shows a diagram of a device according to the invention with a reactor 1, a feed line for hydrocarbon starting material 10, a feed line for carbon particles 11, a discharge line for carbon particles 12 and a discharge line for product gas 13. In the area of the discharge line for product gas, a junction 14 is provided via which part of the product gas can be passed into a compressor 15 and from there again into the reactor.

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List of reference symbols

1 reactor

2 electrodes

3 carbon bulk 4 reactor wall

5 Distribution structure for inert gas

6 upper taper of the reactor cross-section

7 lower taper of the reactor cross-section

8 pyrolysis carbon layer 9 feed gap for inert gas

10 Feed line for hydrocarbon feedstock

11 Feed line for carbon particles

12 Derivation for carbon particles

13 Discharge for product gas 14 Branch

15 compressor

Claims

Expectations

1. A process for the production of hydrogen and pyrolysis carbon from hydrocarbons, the hydrocarbons being converted to hydrogen and carbon in a reactor at temperatures of 1000 ° C or more, and the reactor having two electrodes spaced from one another in the direction of flow of the hydrocarbons, characterized in that, that in the area of the reactor between the electrodes an inert gas component is supplied over the entire reactor cross-section and that the reactor contains carbon particles in the area between the electrodes.

2. The method according to claim 1, characterized in that the carbon particles are passed through the reactor counter to the direction of flow of the hydrocarbons.

3. The method according to claim 1 or 2, characterized in that the hydrocarbons are methane.

4. The method according to any one of claims 1 to 3, characterized in that the inert gas component is nitrogen or hydrogen.

5. The method according to any one of claims 2 to 4, characterized in that the reaction zone is arranged vertically in the reactor space, and that the hydrocarbons pass through the reaction zone from bottom to top and the carbon particles pass through the reaction zone from top to bottom.

6. The method according to any one of the preceding claims, characterized in that the supplied inert gas component has a temperature of less than 1000 ° C, preferably less than 900 ° C and particularly preferably in the range of 200 ° C to 800 ° C.

7. The method according to any one of the preceding claims, characterized in that part of the product gas generated in the process is fed to the reactor as an inert gas component.

8. The method according to any one of the preceding claims, characterized in that the inert gas is introduced into the reactor at an angle of 30 to 60 °, preferably about 45 °, counter to the direction of flow of the hydrocarbons.

9. The method according to any one of the preceding claims, characterized in that the temperature in the reaction zone is kept in the range from 1000 ° C to 1800 ° C, preferably in the range from 1200 ° C to 1500 ° C.

10. The method according to any one of the preceding claims, characterized in that the hydrocarbons are fed into the reactor at a flow rate in the range from 0.001 m / s to 10 m / s.

11. The method according to any one of the preceding claims, characterized in that the inert gas component is fed into the reactor at a flow rate in the range from 0.001 m / s to 100 m / s.

12. The method according to claim 2 or any claim dependent thereon, characterized in that the Koh len substance particles are fed into the reactor at a flow rate in the range from 0.5 m / h to 100 m / h.

13. Apparatus for the pyrolytic conversion of hydrocarbons to hydrogen and carbon comprising a reactor (1) with a reactor space which has two electrodes (2) spaced apart in relation to the flow direction of the hydrocarbons in the flow direction, via which the reactor can be heated with resistance, and has a supply device for an inert gas which is attached in the region between the electrodes of the reactor and which extends over the entire reactor cross-section.

14. The device according to claim 13, characterized in that the feed device is designed such that the reactor cross-section tapers above and / or below the gas inlet opening.

15. The device according to claim 13, characterized in that the feed device is designed so that the reactor cross-section in the area is uniform between the electrodes except for the outlet for inert gas from the supply device.

16. The device according to at least one of claims 13 to 15, characterized in that the feed device is designed so that the inert gas is fed into the reactor via a gap (9) of height Hl, Hl being selected so that when When the inert gas flows through, a pressure loss Dr is established, which ensures that the gas component is distributed over the entire cross section.

17. The device according to at least one of claims 13 to 16, characterized in that the feed device is designed so that the inert gas can be introduced into the reactor at an angle of 30 to 60 °, preferably about 45 °, counter to the direction of flow of the hydrocarbons .

18. The device according to at least one of claims 13 to 17, characterized in that it has a discharge line for product gas (13) formed in the reactor, and that the discharge line has a branch line (14) via which part of the product gas via the feed device for inert gas can be returned to the reactor.

19. The device according to at least one of claims 13 to 18, characterized in that it has a compressor (15) in the region of the branch line.

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