Method for producing hydrogen from dme (dimethyl ether) and system for carrying out said method

Abstract

The present invention relates to a method for producing hydrogen from DME (dimethyl ether) by way of reforming, wherein the reforming is carried out at a pressure in the range from 15 bar to 70 bar, preferably in the range from 20 bar to 40 bar, and at a reformer exit temperature in the range from 750°C to 1050°C, and a nickel- or cobalt-based catalyst material is used for the reforming process. The invention also relates to a system for producing hydrogen from DME.

Description

[0001] DESCRIPTION

[0002] Process for the production of hydrogen from DME (dimethyl ether) and plant for carrying out the process

[0003] The present invention relates to a process for producing hydrogen from DME (dimethyl ether) by reforming. Furthermore, the invention relates to a plant for producing hydrogen from DME using a reformer.

[0004] For example, the reforming of DME to hydrogen (H2) and carbon dioxide (CO2) is being researched as an H2 fuel for fuel cells, as described in the article "Research of hydrogen production by dimethyl ether reforming in fuel cells" by Lei Guo, Open Access Library Journal, Vol. 05 No. 01 (2018), Article ID: 81839 DOI :.4236 / OALIB.1104266.

[0005] The following equations play a role in the production of DME or its reforming.

[0006] Steam reforming of DME (net reaction):

[0007] CH3OCH3 + 2 H2O 6 H2+ 2 CO2, A H298 = 86 kJ / mol in equilibrium with

[0008] WGS: CO + H2O - CO2+ H2, A H298 = -41 kJ / mol.

[0009] Methanol (MeOH) decomposition: CH3OH + H2O — CO + 2 H2, A H298 = 91 kJ / mol.

[0010] DME decomposition:

[0011] CH3OCH3 + H2O - 2 CH3OH, AH 298 = 37 kJ / mol.

[0012] The abbreviation WGS stands for the water gas shift reaction, which is also known as the water-gas conversion reaction or water-gas shift reaction.

[0013] Various publications deal with a catalyst for steam and autothermal reforming under low pressure and temperatures below 500°C. Different catalyst materials are used, always combining an acidic catalyst for converting DME with H2O to methanol and a methanol catalyst with WGS functionality. In this context, reference is made to the articles "Unravelling the role of ceria in improving the stability of Mo2C-based catalysts for the steam reforming of dimethyl ether" by Jing-Hong Lian et al., Catal. Sei. Technol., 2021, Issue 11, 5570-5578 and "Hydrogen production by steam reforming of DME in a large-scale CFB reactor. Part I: Computational model and predictions" by Francis A. Elewuwa and Yassir T.Makkawi, International Journal of Hydrogen Energy, 2015, Volume 40, Issue 46, pages 15865-15876 and “Steam reforming of dimethyl ether” by Kaoru Takeishi and Hiromitsu Suzuki, Applied Catalysis A: General, 2004, Volume 260, Issue 1, pages 111-117 and “Thermodynamics of Hydrogen Production from Dimethyl Ether Steam Reforming and Hydrolysis” by Troy A. Semelsberger and Rodney L. Borup, Los Alamos National Laboratory, LA-14166, October 2004, Web. doi:10.2172 / 836682. and “Hydrogen production and temperature control for DME autothermal reforming process” by Tie-qing Zhang et al., Energy, Volume 239, Part A, 2022, 121980. It is also known to perform steam reforming of methane and hydrocarbon gases, up to LPG, using a nickel-based catalyst at elevated pressures of up to 40 bar and temperatures between 750°C and 950°C. This is described, for example, in the book "Concepts in Syngas Manufacture," Katalytic Science Series: Vol.10 (2011) by Jens Rostrup-Nielsen and Lars J. Kristiansen.

[0014] The known processes for reforming MeOH and DME suffer from the disadvantage of catalyst deactivation. Furthermore, the reactor's DME and MeOH slip increases dramatically at higher pressures, leading to a comparatively complex hydrogen gas purification process.

[0015] It is an object of the present invention to provide an alternative process for producing hydrogen from DME that avoids or at least reduces the disadvantages of the prior art and enables efficient and low-maintenance operation. Furthermore, a plant for carrying out the process is to be provided.

[0016] This object is achieved according to the invention in a process of the type mentioned at the outset in that the reforming is carried out at a pressure in the range from 15 bar to 70 bar, preferably in the range from 20 bar to 40 bar, and at a reformer outlet temperature in the range from 750°C to 1050°C and a nickel- or cobalt-based catalyst material is used for the reforming process.

[0017] The second object is achieved according to the invention in a plant of the type mentioned at the outset in that the reformer is designed to carry out steam reforming of DME at a pressure in the range from 15 bar to 70 bar, preferably in the range from 20 bar to 40 bar, and at a reformer outlet temperature in the range from 750°C to 1050°C, preferably in the range from 775°C to 1050°C, and the reformer comprises a nickel- or cobalt-based catalyst material, and that a DME evaporation device is provided upstream of the reformer.

[0018] The invention is therefore based on the idea of ​​producing hydrogen from DME at higher temperatures and higher pressures, in contrast to the state of the art. Specifically, the temperature and pressure ranges previously reserved for hydrogen production from other starting materials are used. According to the invention, a nickel (Ni) or cobalt (Co)-based catalyst material is used, with a Ni-based catalyst material proving particularly suitable. These catalyst materials are characterized by greater stability and lower costs compared to those previously used for DME steam reforming to produce hydrogen at lower pressures and temperatures.

[0019] It is preferred that an optionally supported Ni-based catalyst material with a Ni content of at least 2 wt.%, preferably at least 5 wt.%, is used.

[0020] Hydrogen production under elevated pressure makes it possible to dispense with a downstream compressor. The hydrogen produced can be used for further applications without compression, for example, fed into a pipeline and transported to a point of use or used for heating purposes. Since hydrogen compressors in particular are generally subject to a comparatively high error or failure rate, maintenance effort can be avoided and downtimes can be significantly reduced. Furthermore, conventional components can be used at least partially to carry out the process according to the invention or for the plant according to the invention, in particular components that have previously been used for hydrogen production by steam reforming of methane or hydrocarbon gases.

[0021] The process according to the invention does not need to include a desulfurization process, since DME does not contain sulfur. Accordingly, the plant according to the invention does not require a desulfurization device.

[0022] The reformer is, in a conventional manner, a reactor in which the reforming process is carried out or can take place. The reformer can, for example, be tubular, particularly cylindrical.

[0023] The reformer can, for example, be a fired, particularly gas-fired, reformer with a burner. Alternatively or additionally, it is possible for the reformer to be electrically heated or to be electrically heated.

[0024] The reformer can be designed as a steam reformer or autothermal reformer.

[0025] If it is designed as a steam reformer, the steam reforming is carried out in particular at a reformer outlet temperature in the range of 750°C to 950°C, preferably in the range of 775°C to 950°C. In an advantageous embodiment, a steam reformer comprises two or more reformer tubes, each of which is equipped with the catalyst material, in particular at least partially filled with it. If the reformer is designed as an autothermal reformer, the steam reforming is preferably carried out at a reformer outlet temperature in the range of 950°C to 1050°C. During autothermal reforming, a portion of oxygen (O2) is added in a sufficiently well-known manner, which provides the heat of reaction through partial combustion of DME. External heating is then unnecessary.

[0026] The reformer outlet temperature refers in particular to the gas temperature at the outlet or exit of the reformer. The gas exiting the reformer can also be referred to as synthesis gas. As a rule, the gas temperature at the reformer outlet is the maximum gas temperature in the reformer. The temperature distribution in the direction of gas flow through the reformer can, in particular, be such that the gas temperature initially decreases slightly after entering the reformer and then, starting from a minimum, increases continuously up to a maximum temperature, particularly present at the exit or exit of the reformer. The exit is preferably considered to be the point at which the catalyst bed ends.If the reformer is designed, for example, as a steam reformer with a plurality of reformer tubes, it is advantageous for the reforming to be carried out in at least one, preferably all, of the plurality of reformer tubes at a reformer outlet temperature in the range of 750°C to 1050°C, preferably in the range of 750°C to 950°C. Thermocouples are suitable for measuring the reformer outlet temperature in a conventional manner.

[0027] The fact that reforming is carried out at a pressure in the range of 15 bar to 70 bar means, in particular, that this pressure is present at the H2 product. To achieve this, the feed gas pressure at the reformer inlet generally requires a pressure 5 bar higher. Accordingly, it is preferred that DME feed gas be admitted into the reformer at a pressure in the range of 20 bar to 75 bar, preferably in the range of 25 bar to 45 bar. If the reformer is designed, for example, as a steam reformer with a plurality of reformer tubes, it is expedient for reforming to be carried out in at least one, preferably all, of the plurality of reformer tubes at a pressure in the stated ranges.

[0028] In the case of a fired reformer with a burner being used, it has proven advantageous for the flue gas to be partially condensed. Heat integration of the flue gas can be provided to further increase efficiency, and the partial condensation of the flue gas can take place in a final stage of heat integration. The condensation enthalpy can be used in particular to heat the DME feed, the combustion air and / or to heat water. Accordingly, if the plant according to the invention comprises a reformer with a burner, it can comprise a condensation device for partially condensing the flue gas, in particular in a final stage of flue gas heat integration. A heat exchanger provided for condensation is expediently made at least partially of stainless steel.

[0029] One embodiment of the process according to the invention is characterized in that a catalyst bed with at least two, preferably exactly two, layers is used. Then, at least one, preferably exactly one, layer can comprise or consist of an acidic catalyst material, in particular gamma-alumina or a zeolite, and at least one further, preferably exactly one further, layer can comprise or consist of a nickel- or cobalt-based catalyst material.Accordingly, in the plant according to the invention, in a further development, the reformer can comprise a catalyst bed with at least two, preferably exactly two, layers, wherein at least one, preferably exactly one, layer comprises or consists of an acidic catalyst material, in particular gamma-aluminum oxide or a zeolite, and at least one further, preferably exactly one further, layer comprises or consists of a nickel- and / or cobalt-based catalyst material, or wherein two layers comprise or consist of a nickel-based catalyst material.

[0030] A combination with an acid catalyst has proven particularly suitable for steam reformers.

[0031] In the case of two layers with or made of a nickel-based catalyst material, it is preferred that these two layers differ from each other, e.g. with regard to their nickel content or doping.

[0032] The catalyst material can be located on a support or carrier material. Ni-based catalyst materials are often arranged on a support material such as alumina.

[0033] A further advantageous embodiment of the process according to the invention is characterized in that a catalyst bed is used which comprises a first and a second region, wherein the first region comprises or is formed by a first catalyst material and the second region comprises or is formed by a second catalyst material different from the first catalyst material.

[0034] The system according to the invention can accordingly be characterized in that the reformer has a catalyst bed comprising a first and a second region, wherein the first region comprises or is formed by a first catalyst material, and the second region comprises or is formed by a second catalyst material different from the first catalyst material. The two regions can be directly adjacent to one another, in other words, have no separation from one another. The catalyst bed can have exactly two regions. It can be divided into the two regions.

[0035] The catalyst bed can further be configured and arranged in a reformer used for the reforming process such that the DME and / or a product resulting from the DME during the reforming process flows through the first and second regions one after the other. The arrangement is, in particular, such that the first region flows through before the second region. The two regions are preferably located one behind the other in the direction of flow through the reformer.

[0036] It may further be preferred that the first catalyst material is an acidic catalyst material and the second catalyst material is a nickel- or cobalt-based catalyst material.

[0037] Alternatively or additionally, the first region is arranged upstream of the second region.

[0038] The reformer, which may be configured, for example, as a steam reformer, may comprise at least one reformer tube, which is preferably arranged vertically and in which the catalyst bed is arranged. The first region is then advantageously located at the top and the second region at the bottom of the reformer tube. The catalyst bed may, for example, comprise a catalyst bed or be provided by such a bed, which has proven particularly advantageous.

[0039] In a particularly advantageous embodiment of the process according to the invention, it is further provided that a CO2 capture process is carried out after the reforming process. It should be emphasized that "after" means that the CO2 capture process does not have to follow immediately, in other words directly, the reforming process. Rather, further steps can be carried out between reforming and CO2 capture, e.g., cooling and / or a water gas shift reaction in at least one water gas shift reactor.

[0040] It is preferable that CO2 capture takes place in the process gas rather than in the flue gas.

[0041] CO2 capture is further preferably carried out by chemical scrubbing, in particular amine scrubbing in one or two stages, and / or by physical scrubbing, in particular based on methanol and / or DME, and / or by a membrane process and / or by an adsorption process. It is also possible for CO2 capture to be carried out by a condensation process or to include such a process, preferably with the cooling required for condensing the CO2 being provided by an open or closed refrigeration circuit containing DME as the refrigerant. CO2 capture can also comprise a combination of two or more of the aforementioned processes.

[0042] Alternatively or additionally, CO2 capture can be carried out with a CO2 capture rate of at least 55%, in particular at least 75%, preferably with a CO2 capture rate in the range of 80% to 99%. The percentages refer in particular to a molar ratio of captured CO2 molecules to C molecules entering the feed stream. Purely as an example, for 1 mole of DME feed stream (equivalent to 2 moles of C feed), 1 mole of CO2 is captured, which would correspond to a capture rate of 50%.

[0043] In the system according to the invention, a CO2 capture device of appropriate design can be provided downstream of the reformer. The CO2 capture device can be connected directly downstream of the reformer or via one or more additional devices that are then connected between the reformer and the CO2 capture device.

[0044] If a fired, particularly gas-fired, reformer with a burner is used, it can be provided to increase efficiency by feeding gas originating from the CO2 capture process to the burner and using it as fuel. In the system according to the invention, at least one connecting line connecting the CO2 capture device and the burner can be provided for this purpose, via which the gas originating from the CO2 capture device can be fed to the burner.

[0045] Alternatively or additionally, recycling from the CO2 capture device to the reformer is possible not as fuel for a burner, but as input gas for reforming. This is used to recover CO, methane, and DME. The plant according to the invention can accordingly have at least one connecting line connecting the CO2 capture device and the reformer, in particular its feed gas inlet. A further advantageous embodiment of the process according to the invention is characterized by the use of a gas-heated auxiliary reformer. It has proven expedient to supply the auxiliary reformer with synthesis gas obtained in the reformer for heating.

[0046] The plant according to the invention can be characterized in an analogous manner in that a gas-fired additional reformer is provided, wherein the additional reformer can be heated by means of synthesis gas obtained in the reformer. One can also say that the hot synthesis gas exiting the reformer serves as heating gas for the additional reformer. This can further increase efficiency. Hot synthesis gas taken from the reformer can be the only heat source used by the additional reformer. In particular, the additional reformer is not or will not be fired. It is possible for the entire synthesis gas exiting the reformer to be used as a heat source for the additional reformer. After the synthesis gas has been passed through the additional reformer and has released part of its thermal energy there, it can be subjected to further process steps to obtain an H2 product.

[0047] The synthesis gas used as fuel gas does not come into contact with the catalyst material of the additional reformer. For example, if the additional reformer comprises several tubes filled with catalyst material, the synthesis gas used as fuel gas is conveniently routed over the outside of the tubes, which do not contain any catalyst material.

[0048] The auxiliary reformer can be connected upstream of the reformer or in parallel with it, with the upstream or parallel connection referring in particular to the feed gas flow or the DME / synthesis gas flow through the plant. In the upstream connection, the DME feed gas, preferably the entire feed gas flow, is passed through the auxiliary reformer and the downstream reformer. The hot outlet gas from the reformer is returned to the auxiliary reformer to serve as fuel gas.

[0049] In the case of parallel operation, the feed gas stream to the reformer is divided. This is distributed between the reformer and the auxiliary reformer, with a larger proportion of the feed gas generally being fed to the reformer than to the parallel auxiliary reformer. The hot outlet gas from the reformer is fed to the parallel auxiliary reformer as heating gas, where its thermal energy is utilized. After the outlet gas from the reformer passes through the auxiliary reformer as heating gas and releases heat there, it is mixed with the outlet gas from the auxiliary reformer; in other words, the two synthesis gas streams are combined or mixed.

[0050] It has proven particularly suitable if the reformer is designed as an autothermal reformer and the additional reformer as a steam reformer or if both the reformer and the additional reformer are designed as steam reformers.

[0051] Alternatively or additionally, it is also possible to use an adiabatic pre-reformer upstream of the reformer. "Upstream" refers to the feed gas stream. The plant according to the invention can comprise such a pre-reformer, which is also referred to as a pre-reformer. If an adiabatic pre-reformer is present, it preferably has an acidic catalyst material or a Ni-based catalyst material with a higher Ni loading than the catalyst material of the reformer. The synthesis gas obtained by the reforming taking place in the reformer, in particular steam reforming or autothermal reforming, is expediently cooled. For this purpose, a cooling device can be provided downstream of the reformer.

[0052] To increase the hydrogen yield, it can further be provided that the synthesis gas obtained by reforming in the reformer is subjected to a water gas shift reaction. This preferably takes place after cooling. At least one water gas shift reactor can be provided for this purpose downstream of the reformer and preferably a synthesis gas cooling device. It is also possible to use two or more water gas shift reactors, in particular connected in series. For example, a high-temperature shift in the range from 300°C to 450°C can take place in a high-temperature water-gas shift reactor, in particular up to a CO content in the range from 4 vol% to 2.5 vol% CO, and a subsequent medium-temperature shift in the range from 220°C to 270°C in a medium-temperature water-gas shift reactor, in particular up to a CO content in the range from 2 vol% to 0.5 vol% CO.As an alternative to a medium-temperature shift or in addition to and following such a shift, a low-temperature shift in the range from 180°C to 250°C can be carried out in a low-temperature water-gas shift reactor, in particular up to a CO content in the range from 1 vol% to 0.2 vol% CO.

[0053] A high-temperature water gas shift reactor can, for example, be designed as an adiabatic reactor and / or comprise an iron-based catalyst and a chromium-based catalyst. A medium-temperature water gas shift reactor can, for example, be designed as a cooled isothermal reactor and / or comprise a copper-based catalyst. A low-temperature water gas shift reactor can, for example, be designed as an adiabatic reactor and / or comprise a copper-based catalyst and a zinc-on-alumina catalyst.

[0054] The CO2 separation can then be carried out, in particular, after the water gas shift reaction in one or more water gas shift reactors. A CO2 separation device of the plant according to the invention can accordingly preferably be provided downstream of the water gas shift reactor(s).

[0055] It should be noted that further treatment steps can and preferably do occur between the water gas shift reaction and the CO2 separation. For example, cooling and condensation separation can also occur after the water gas shift reaction. Accordingly, the system according to the invention can comprise a cooling device and a condensation separation device, which can be connected between a (final) water gas shift reactor and a CO2 separation device.

[0056] Furthermore, it can be provided that a "recycling" takes place from the CO2 capture device to the or at least one water gas shift reactor. This is done for the recovery of CO, methane, and DME. Therefore, in a further development, the system according to the invention can have at least one connecting line connecting the CO2 capture device and the or at least one water gas shift reactor.

[0057] In a further development of the process according to the invention, hydrogen purification is further carried out after CO2 separation. This can also be referred to as hydrogen purification. Hydrogen purification can be carried out, in particular, by pressure swing adsorption or can include this process. The plant according to the invention can have a hydrogen purification device downstream of the reformer, which, in a preferred development, comprises at least one pressure swing adsorption reactor.

[0058] In an advantageous development of the process according to the invention, a gas originating from the hydrogen purification, which preferably comprises H2, CH4, and CO, is compressed and fed to the inlet side of a reformer used for the reforming process, in particular together with the DME. If the hydrogen purification is carried out by pressure swing adsorption, it is advantageous for a tail gas from the pressure swing adsorption to be compressed and fed to the inlet side of the reformer together with the DME.

[0059] The system according to the invention can be characterized accordingly by providing a connecting line connecting the hydrogen purification device and the reformer, via which a gas originating from the hydrogen purification device, preferably comprising H2, CH4, and CO, in particular a tail gas from pressure swing adsorption, can be fed to the reformer on the inlet side, preferably together with the DME. Furthermore, a compressor is provided for compressing the gas originating from the hydrogen purification device, in particular the PSA partial gas, so that the gas can be returned to the reformer in a compressed state.

[0060] In these embodiments, in other words, a return, or one could also call it "recycling," takes place from the hydrogen purification (device) to the reformer. This is possible due to the use of DME as the feed gas. Since DME contains few inerts, such as N2 or Ar, no outlet is required for these substances. They can enter the H2. Since the concentration of inerts such as N2 and Ar in DME is low, the concentration of these components in the H2 is also low.

[0061] The tail gas of pressure swing adsorption is understood to be a gas that contains, or is provided by, the (gas) components adsorbed during the higher pressure phase and subsequently desorbed for regeneration. The tail gas, which has a comparatively low pressure, is compressed, returned to the reformer, and reformed with the DME, in particular, converted into syngas.

[0062] If the reformer is designed as a fired reformer with a burner, at least one connecting line can be provided connecting the hydrogen purification device and the burner, via which a gas originating from the hydrogen purification device can be fed to the burner and used as fuel. If the hydrogen purification includes pressure swing adsorption or the plant's hydrogen purification device comprises at least one pressure swing adsorption reactor, PSA tail gas, in particular, can be fed to the burner.

[0063] The hydrogen purification system can also be integrated into the CO2 capture system. The CO2 capture system can, for example, comprise a module for CO2 capture by chemical and / or physical scrubbing and / or by membrane and / or adsorption processes, and a pressure swing adsorption reactor, in particular downstream of this module.

[0064] Since dimethyl ether is usually transported in liquid form, it is expedient to supply the DME in liquid form and evaporate it before entering the reformer, in particular a steam reformer or autothermal reformer. In the system according to the invention, a DME evaporation device is provided upstream of the reformer.

[0065] In a preferred embodiment, a thermal energy storage device is also used to provide the energy required for the DM E evaporation during a start-up phase. The system according to the invention can comprise a thermal energy storage device, via which the DME evaporation device can be supplied with thermal energy.

[0066] A cooling device for cooling the synthesis gas obtained by reforming can be provided downstream of the reformer. The synthesis gas or its cooling process can also be used to obtain steam. The cooling device can comprise or be formed by a heat exchanger, and the heat exchanger can have at least one line for synthesis gas and at least one line for water. The water line can be part of a steam generation device of the system according to the invention, located upstream of the reformer.

[0067] It has also proven advantageous if the vaporized DME is superheated before entering the reformer. A superheating device can be provided upstream of the reformer. This is expediently arranged downstream of the DME evaporation device. The superheating device is or will preferably be electrically powered. An example of this is an electric process gas heater. Superheating can also occur in the flue gas. Steam is usually added beforehand. A steam generation device can also be provided upstream of the reformer. If such a device is present, it can be fed via a thermal energy storage device, in other words, supplied with heat energy, particularly during a start-up phase. A thermal energy storage device can be used, which is also accessed by the DME evaporation device during a start-up phase.

[0068] If a superheating device and a steam generation device are present, an advantageous further development is that the superheating device is connected on the inlet side to an outlet of the DME evaporation device and to an outlet of the steam generation device in order to be able to superheat a mixture of evaporated DME and steam.

[0069] In the process according to the invention, it can be provided that evaporated DME is mixed with steam and the mixture of DME and steam is superheated.

[0070] The steam / DME ratio is preferably in the range of 3 to 10, preferably 4 to 8, on a molar basis. A ratio within these ranges can be adjusted within the process.

[0071] A further advantageous embodiment of the process is further characterized in that no combustion of a purge stream, in particular a gas purge stream, takes place. In a further development, the system according to the invention accordingly does not require components for such a purge stream.

[0072] In particular, if an electrically heated reformer, an autothermal reformer, or a combination of an electrically heated reformer and an autothermal reformer is planned instead of a fired reformer, an outlet for inert components (purge stream) is usually required, since the plant lacks a reformer burner. However, due to the high purity of the DME feed, it is possible to implement a process and plant without the need for a gas purge, which must be combusted. Gas-phase impurities such as CH4 and N2 escape with H2, and liquid-phase impurities with CO2. It is possible to provide a liquid purge and possibly degassing in the condensate or steam system to prevent accumulation.

[0073] Even if the process and the plant according to the invention can operate without combustion of a purge stream, it is not excluded that such a purge stream will occur, in particular if a reformer with a burner is present.

[0074] With regard to the embodiments of the invention, reference is also made to the dependent claims and to the following description with reference to the accompanying drawings. The drawing shows:

[0075] Figure 1 is a diagram schematically illustrating a first embodiment of the process according to the invention for producing hydrogen from DME;

[0076] Figure 2 shows a diagram of the recycling of PSA tail gas from a hydrogen purification device 8;

[0077] Figure 3 is a diagram schematically illustrating a second embodiment of the process according to the invention for producing hydrogen from DME; Figure 4 is a diagram schematically illustrating a third embodiment of the process according to the invention for producing hydrogen from DME;

[0078] Figure 5 is a diagram in which a fourth embodiment of the process according to the invention for producing hydrogen from DME is schematically shown

[0079] Figure 6 is a diagram schematically showing a fifth embodiment of the process according to the invention for producing hydrogen from DME;

[0080] Figure ? a diagram in which a sixth embodiment of the process according to the invention for producing hydrogen from DME is schematically shown; and

[0081] Figure 8 is a diagram in which a seventh embodiment of the process according to the invention for producing hydrogen from DME is schematically shown; and

[0082] Figure 9 is a highly simplified, purely schematic sectional view through a reformer tube in which a catalyst bed is arranged, comprising a first and a second region through which the catalyst flows one after the other.

[0083] In the figures, identical or corresponding elements are provided with the same reference numerals.

[0084] Figure 1 shows a purely schematic representation of a first embodiment of the process according to the invention for producing hydrogen from DME by reforming. The process is carried out in a plant, some components of which are indicated purely schematically in Figure 1 by rectangular block elements. This plant represents a first embodiment of a plant according to the invention. The arrows AJ indicate a material or gas flow through the plant during operation or the associated fluidic connecting lines.

[0085] The plant comprises a DME evaporation device 1 and a steam generation device 2, both of which are connected upstream of a superheating device 3 of the plant. The superheating device 3, in turn, is connected upstream of a reformer 4. In the embodiment shown in Figure 1, this is a steam reformer designed as a cylindrical tube-shaped reactor in which the steam reforming of DME can take place. The steam reformer 4 comprises a nickel-based catalyst material (not shown separately in Figure 1).

[0086] Downstream of the reformer 4 is a cooling device 5 for cooling synthesis gas, which is obtained during operation by the reforming process taking place in the reformer 4, in this case steam reforming, and exits the reformer 4 at the outlet side. A water gas shift reactor 6 is provided downstream of the cooling device 5 and thus also downstream of the reformer 4.

[0087] A CO2 capture device 7 is also connected downstream of the water gas shift reactor 6 to capture CO2 from the synthesis gas obtained by reforming. The CO2 capture process is also referred to as "carbon capture," or CC for short.

[0088] During operation, liquid DME is fed to the DME evaporator 1, as indicated by arrow A in Figure 1, and the DME is evaporated in the DME evaporator 1, in other words, converted into a gaseous state. During a start-up phase, a thermal energy storage device of the system (not shown separately in Figure 1) can be used to provide the heat energy required for the evaporation of the liquid DME.

[0089] At the same time, water is supplied to the steam generation device 2, as indicated by arrow C in Figure 1, and this water is evaporated in the steam generation device 2. For this purpose, too, at least during the start-up phase of the system, a thermal energy storage device can be used, whereby the same thermal energy storage device can be used as for the DME evaporation device 1.

[0090] As indicated by arrow B, gaseous DME is fed from the DME evaporator 1 into the superheater 3. Steam produced in the steam generator 2 is also fed into the superheater 3. This is indicated by arrow D.

[0091] The two arrowheads without lines on the steam generation device 2 are intended to indicate an energy flow.

[0092] In the superheating device 3, a mixture of gaseous DME and steam is obtained and superheated. The superheating can be achieved electrically, for example, using an electric process gas heater (also known as a "flow heater"). The superheated mixture is fed to the steam reformer 4, as indicated by arrow E.

[0093] Reforming takes place in the reformer 4, wherein this is carried out at a pressure in the range of 15 to 70 bar, preferably in the range of 20 to 40 bar, and at a steam reformer outlet temperature in the range of 750°C to 1050°C. The reformer 4 is designed to be operated at these temperatures and pressures. The nickel-based catalyst material arranged in the steam reformer 4 is used for the reforming process. It should be noted that it is also possible to use a catalyst bed with at least two catalyst layers. One can also say that a catalyst bed is used which comprises two regions or layers. Accordingly, such a bed can also be arranged in the reformer 4. A corresponding embodiment will be discussed in more detail below in connection with Figure 9. If the reformer 4 is designed as a steam reformer, one layer or layer orOne region is an acidic catalyst, or comprises one such as gamma alumina, and a second layer or layer or a second region is a nickel- or cobalt-based catalyst or comprises one such catalyst. Particularly for an autothermal reformer, two layers / layers / regions made of or with a Ni-based catalyst material have also proven successful.

[0094] The reformer 4 can be an electrically heated reformer 4 or a fired, particularly gas-fired, reformer 4. Electrically heated steam reformers are sometimes also referred to as e-SMRs for short. It is also possible to use a combination of electrical and fired heating of or for the reformer 4. The reformer 4 can be designed to be heated both electrically and by a fire. If the reformer 4 is (also) designed as a fired reformer 4, it expediently has at least one burner (not shown separately in Figure 1).

[0095] The synthesis gas obtained by reforming, which exits reformer 4, is fed to cooling device 5 and cooled therein. The gas flow between reformer 4 and cooling device 5, or a corresponding connecting line, is represented in Figure 1 by arrow F. Purely by way of example, the reforming process is controlled, at least temporarily, such that the steam reformer outlet temperature is approximately 900°C. The synthesis gas leaving reformer 4 at this temperature, for example, can be cooled in cooling device 5 to 300 to 400°C, for example.

[0096] To increase efficiency, the synthesis gas cooling process can also be used - particularly after a start-up phase of the plant - to generate steam from liquid water. For this purpose, the cooling device 5 can, for example, have at least one heat exchanger or be formed by at least one heat exchanger that has at least one line for synthesis gas and at least one line for water. The at least one line for water can be a component of the steam generation device 2. It should be noted that in the schematic, highly simplified Figure 1, the internal structure of the steam generation device 2 and the cooling device 5 are not shown, and corresponding lines are not visible.

[0097] The synthesis gas cooled in the cooling device 5 then enters the water gas shift reactor 6, as indicated by arrow G. There, it undergoes a water gas shift reaction to increase the hydrogen yield. It should be noted that the plant can also have more than one water gas shift reactor 6, which are then expediently connected in series and passed through one after the other. For example, two or more water gas shift reactors 6 can cover different temperature ranges. For example, a high-temperature shift in the range of 300 to 450°C and a subsequent medium-temperature shift in the range of 220 to 270°C or a low-temperature shift in the range of 180°C to 250°C can be provided.

[0098] The gas exiting the water gas shift reactor 6 at the outlet side is fed to the CO2 separation device 7 (arrow H). It should be noted that the gas exiting the water gas shift reactor 6 can be used to evaporate DME. For this purpose, a heat exchanger can be connected between the water gas shift reactor 6 (or, in the case of several reactors, in particular the last one) and the CO2 separation device 7. This heat exchanger can comprise at least one line for gas exiting the water gas shift reactor 6 and at least one line for liquid DME. The at least one line for liquid DME can be part of the DME evaporation device 1. Furthermore, it should be noted that in the schematic, highly simplified Figure 1, the heat exchanger downstream of the water gas shift reactor 6 and the internal structure of the DME evaporation device 1 are not shown, and corresponding lines are therefore not visible.

[0099] In the CO2 separation device 7, a CO2 separation process takes place with a separation rate of 55% or more, preferably of 75% or more, in particular a separation rate in the range of 80% to 99%.

[0100] The CO2 capture in the process gas can be carried out in particular by one of the following processes, or combinations of two or more of these processes:

[0101] • chemical washing, especially amine washing in one or two stages,

[0102] • physical scrubbing, particularly based on methanol and / or DME, membrane processes,

[0103] Adsorption process, condensation process.

[0104] The system can also include a hydrogen purification device, which, for example, is provided by or includes a pressure swing absorption reactor. The hydrogen purification device can be integrated into the CO2 separation device 7, which is the case in the embodiment shown in Figure 1. For example, the CO2 separation device can include a CO2 separation module and, in particular, a downstream pressure swing absorption reactor for hydrogen purification.

[0105] Alternatively, it is also possible to provide a separate hydrogen purification device 8, expediently connected downstream of the CO2 separation device 7, which preferably comprises or is provided by a pressure swing absorption reactor. While such a separate hydrogen purification device 8 is not visible in Figure 1, it is shown in Figure 2, which shows some components of the system shown in Figure 1. In Figure 2, which is also greatly simplified, the components 1, 2, 3 for the pretreatment of the DME feed are shown combined in a single block element. The gas fed from the CO2 separation device 7 into the hydrogen purification device 8, or a corresponding connecting line, is indicated in Figure 2 by the arrow H1.Separate CO2 separation devices 7 and hydrogen purification devices 8 can also be seen in Figures 6, 7 and 8, which show further embodiments of the process according to the invention or of the systems according to the invention in a highly simplified, purely schematic representation. From the CO2 separation device 7 or the hydrogen purification device 8, a "recycling" can take place to the water gas shift reactor 6 and / or to the reformer 4, not to its burner as fuel gas, but as input gas for reforming in order to recover CO, methane and DME. This can further increase efficiency. In Figure 2, the arrow K indicates PSA tail gas discharged from the hydrogen purification device 8 or an associated line, which is fed to a compressor 9 and then guided to the feed gas inlet of the reformer 4, as shown by the arrow L.The PSA tail gas originating from the hydrogen purification comprises H2, CH4, and CO. The corresponding recirculation of PSA tail gas from the hydrogen purification is also visible in Figure 8. The dash-dotted arrow M in Figure 2 illustrates an optional "recycling" to the water gas shift reactor 6, and a dash-dotted arrow N illustrates an optional minimum purge stream.

[0106] Furthermore, as indicated by arrow I in Figure 1, gas originating from the CO2 capture device 7 is returned to the reformer 4, specifically the burner of the reformer 4, to serve as fuel. This further increases the efficiency of the plant. In particular, unconverted CO and / or tail gas from pressure swing adsorption, also referred to as PSA tail gas (for pressure swing adsorption), can be fed to the burner and serve as fuel. For this "recycling," the plant includes a connecting line that fluidically connects the CO2 capture device 7 to the reformer 4, specifically its burner. It should be noted that the burner of the reformer 4 is not shown separately in Figures 1 and 2, as well as Figures 3 and 5. This is only the case in Figures 6 and 7, which will be discussed in more detail below.The finished H2 product exits the CO2 capture device 7 at the outlet side, indicated by arrow J in Figures 1 and 2. Since the DME reforming in the reformer 4 is carried out at higher pressures than in the prior art, the H2 product is already available at sufficient pressure. The plant thus does not require a hydrogen compressor. The hydrogen can, for example, be fed directly into a pipeline to reach a desired location. The plant according to the invention also does not require desulfurization, since DME does not contain sulfur.

[0107] It should be noted that, alternatively to being a steam reformer, reformer 4 can also be designed as an autothermal reformer. In this case, O2 is supplied in a conventional manner (not shown in Figure 1, but indicated in Figure 2 by the dot-dash arrow O).

[0108] Since the reforming process according to the invention can take place at higher temperatures, it is also possible to counteract slip, in particular CH4 and / or MeOH and / or DME slip of the reformer 4, by increasing the temperature, preferably by suitable adjustment of the reformer outlet temperature. In an advantageous embodiment of the method according to the invention, the slip, in particular the CH4 and / or MeOH and / or DME slip of the reforming process is therefore monitored and the reformer outlet temperature is increased in the event that the slip exceeds a predetermined value. If, for example, the reforming is initially carried out with an outlet temperature of 900°C, as stated above, and (excessively high) slip is detected, the temperature can be increased, for example, to 950°C, to counteract this. In addition, the DC ratio can be increased over the running time to further reduce the slip, e.g. from 5 to 7 over the operating time.It is also possible to use a portion of the ^ product for firing the reformer 4, which can be designed accordingly. A corresponding connecting line to the burner of the reformer 4 can be provided (not shown).

[0109] It has proven particularly advantageous, and above all efficient, if an electrically heated and / or H2 product-fired reformer 4 is provided in combination with a low-temperature shift, in particular down to 180°C, and a "recycling" from the CO2 separation device 7 or the hydrogen purification device 8 to the or, in the case of several, at least one water gas shift reactor 6 and / or to the reformer 4 - in each case as input gas - for the recovery of CO, methane and DME, as shown schematically in Figure 2.

[0110] Figures 3 to 5 illustrate, purely schematically, three further exemplary embodiments of inventive methods carried out in associated systems according to the invention. Here, too, some components of the systems are shown merely as block elements. As can be seen, the three further exemplary embodiments of inventive systems largely correspond to the example in Figure 1. The following merely discusses the differences, and otherwise refers to the above explanations regarding Figure 1.

[0111] The three further embodiments differ from the first example only in that they utilize a gas-fired additional reformer 4a (Figures 3 and 4) and an adiabatic pre-reformer 4b (Figure 5). Figure 3 shows the case of an additional reformer 4a connected in parallel to the reformer 4, and Figure 4 shows the case of one connected in series upstream of the reformer 4.

[0112] In the case of the parallel connection according to Figure 3, the feed gas stream is divided. This is distributed between reformer 4 and the additional reformer 4a (indicated in Figure 3 by the forked arrow E with two arrowheads), with a larger proportion of the feed gas generally being fed to reformer 4 than to the parallel additional reformer 4a. The hot outlet gas from reformer 4 is fed to the parallel additional reformer 4a as heating gas (see arrow Fi in Figure 3), and its thermal energy is utilized there. After the outlet gas from reformer 4 passes through the additional reformer as heating gas and has released heat there, it is mixed with the outlet gas from the additional reformer 4a; in other words, the two synthesis gas streams are combined or mixed. This is indicated in Figure 3 by the converging arrow F2, which connects the synthesis gas outlet and the heating gas outlet of the additional reformer 4a with the cooling device 5.

[0113] In the case of serial connection, the entire feed gas flow is first fed to the upstream additional reformer 4a and then to the downstream reformer 4, as indicated in Figure 4 by arrows E and F1. The hot outlet gas from the reformer 4 is redirected to the additional reformer 4a, specifically to a heating gas inlet thereof, as indicated by arrow F2, to serve as heating gas for the additional reformer 4a. The heating gas outlet of the additional reformer 4a is connected to the cooling device 5 (arrow F3).

[0114] For example, it is possible for an autothermal reformer 4 to be used in combination with an additional reformer 4a designed as a steam reformer. It is also possible for both the reformer 4 and the additional reformer 4a to be designed as steam reformers.

[0115] The adiabatic pre-reformer 4b of the fourth embodiment is, as can be seen in Figure 5, arranged upstream of the reformer 4. Gas exiting the pre-reformer 4b is fed to the reformer 4, as indicated by the arrow F1, and gas exiting the reformer 4 is fed to the cooling device 5 (see arrow F2). It should be noted that a combination of the additional reformer 4a and the pre-reformer 4b is also possible.

[0116] Furthermore, in the embodiments of Figures 3 to 5, gas originating from the CO2 capture device 7 can be or is returned to the burner of the reformer 4, as indicated by arrow I in Figure 1. For reasons of clarity, however, arrow I is not additionally shown in Figures 3 to 5. The same applies to the "recycling" illustrated in Figure 2, which can also be implemented in Figures 3 to 5, although it is not shown again in these figures.

[0117] Figures 6 to 8 illustrate further exemplary embodiments of methods according to the invention and associated systems purely schematically. Here, too, some components of the corresponding systems are shown as block elements, and there are many similarities with the previously described exemplary embodiments. Only the differences will be discussed below, and reference is made to the above explanations, particularly with regard to Figures 1 and 2.

[0118] Figure 6 illustrates in more detail the recirculation of PSA tail gas, which originates from the hydrogen purification device 8 and is removed therefrom and fed to the burner 10 of the reformer 4, shown separately in Figure 6. It should be noted that even though the burner 10 is shown next to the reformer 4 in Figure 6 for reasons of clarity, the latter forms a component of the reformer 4. The same applies to Figure 7. The supply of PSA tail gas to the burner 10 is indicated by arrow I. Figures 6 and 7 also show that DME can be supplied to the burner 10 during a start-up phase (see arrow P, which represents the corresponding supply or an associated connecting line).Another difference between the systems shown in Figure 6 is that a cooling and condensation unit 11 is additionally shown here, arranged between the water gas shift reactor 6 and the CO2 capture device 7. It should be noted that, even though Figures 1 to 5 do not show such a unit, a corresponding unit may also be present there.

[0119] Finally, Figure 6 includes dashed arrows Q and R, which represent an energy and heat flow from the cooling device 5 and the water gas shift reactor 6, respectively, to the steam generation device 2. Further dashed arrows also represent an energy flow.

[0120] The process and system according to Figure 7 comprise – analogously to Figure 2 – the extraction of PSA tail gas from the hydrogen purification device 8, its compression in a compressor 9, and its recirculation to the reformer 4 on the inlet side together with DME. It should be noted that, as shown in Figure 7, compressed PSA tail gas is fed upstream of the superheater 3. A corresponding connecting line, indicated by the arrow L in Figure 7, opens upstream of the superheater 3. In this case, DME is superheated together with the supplied PSA tail gas in the superheater 3 and then fed to the reformer 4. In the process and system of Figure 7 (in comparison with Figure 6), a recirculation of gas to the burner 10 of the reformer 4 is provided.As can be seen in Figure 7, however, this is not the PSA tail gas from the hydrogen purification system 8, as in Figure 6, but rather the hydrogen leaving it. This is indicated in Figure 7 by an arrow S. The advantage of firing the burner 10 with H2 is that no CO2 emissions are generated. Figure 7 also shows that DME can be used to start up the plant, as indicated by the arrow P pointing to the burner 10.

[0121] Figure 8 shows that the extraction of PSA tail gas from the hydrogen purification device 8, compression in the compressor 9, and return to the reformer 4, particularly upstream of the superheating device 3, can also be provided for the case where the reformer 4 is an electric reformer or an autothermal reformer. Otherwise, Figure 8 corresponds to Figure 7.

[0122] Figure 9 shows, in a purely schematic, highly simplified representation, a particularly advantageous embodiment of a catalyst bed 13 which can be used in the process according to the invention. Figure 9 shows, by way of example, a reformer tube 12 in which the catalyst bed 13 is arranged. The catalyst bed 13 is divided into two regions, specifically a first upper region 14 and a second lower region 15, through which flow occurs one after the other from top to bottom in the embodiment shown here. The direction of flow is indicated in Figure 9 by two arrows. The catalyst sheet 13 is provided by a catalyst bed, in other words it is designed as such. The first region 14 of the catalyst bed 13 is provided here by an acidic catalyst material, for example gamma-aluminum oxide.The second region 15 of the catalyst bed 13 is further formed by a nickel- or cobalt-based catalyst material. As can be seen, the first region 14 is arranged above the second region 15. It is understood that a reformer 4 can comprise one or more such reformer tubes 12, of which only one is shown as an example in Figure 9. All reformers 4 of the exemplary embodiments illustrated in Figures 1 to 8 can have a catalyst bed 13 with two regions 14 and 15, as illustrated in Figure 9.

[0123] List of reference symbols

[0124] 1 DME evaporation device

[0125] 2 Steam generation device 3 Superheating device

[0126] 4 reformers

[0127] 4a gas-fired additional reformer

[0128] 4b adiabatic pre-reformer

[0129] 5 Cooling device 6 Water gas shift reactor

[0130] 7 CO2 capture facility

[0131] 8 Hydrogen cleaning device

[0132] 9 Compressor

[0133] 10 Burner 11 Cooling and condensing unit

[0134] 12 burner tube

[0135] 13 catalyst bed

[0136] 14 first area

[0137] 15 second area

Claims

CLAIMS 1. A process for producing hydrogen from DME (dimethyl ether) by reforming, characterized in that the reforming is carried out at a pressure in the range of 15 bar to 70 bar, preferably in the range of 20 bar to 40 bar, and at a reformer outlet temperature in the range of 750°C to 1050°C, and a nickel- or cobalt-based catalyst material is used for the reforming process.

2. The process according to claim 1, characterized in that a catalyst bed having at least two layers is used, wherein at least one layer comprises or consists of an acidic catalyst material, in particular gamma-alumina, and at least one further layer comprises or consists of a nickel- or cobalt-based catalyst material, or wherein two layers comprise or consist of a nickel-based catalyst material.

3. The method according to claim 1 or 2, characterized in that a catalyst bed is used which comprises a first and a second region, wherein the first region comprises a first catalyst material and the second region comprises a second catalyst material which is different from the first catalyst material, and wherein the catalyst bed is designed and arranged in a reformer (4) used for the reforming process such that the first and the second region are successively flowed through by the DME and / or by a product resulting from the DME in the course of the reforming process, preferably wherein the first catalyst material is provided by an acidic catalyst material and the second catalyst material by a nickel- or cobalt-based catalyst material, and / or wherein the first region is arranged upstream of the second region, and / or wherein the catalyst sator bed is arranged in a preferably vertically arranged reformer tube of a reformer (4) used for the reforming process.

4. Process according to one of the preceding claims, characterized in that the catalyst bed comprises or is provided by a catalyst bed.

5. Process according to one of the preceding claims, characterized in that a CO2 capture process is carried out after the reforming process, preferably, wherein the CO2 capture is carried out by chemical scrubbing, in particular amine scrubbing in one or two stages, and / or by physical scrubbing, in particular based on methanol and / or DME, and / or by a membrane process and / or by an adsorption process and / or with a CO2 capture rate of at least 55%, preferably with a CO2 capture rate in the range of 80% to 99%.

6. The method according to claim 5, characterized in that after the CO2 separation, a hydrogen purification is carried out, in particular, wherein a gas originating from the hydrogen purification, which preferably comprises H2 and CH4 and CO, is compressed and fed to a reformer (4) used for the reforming process on the inlet side, in particular together with the DME, preferably, wherein the hydrogen purification is carried out by pressure swing adsorption and a tail gas of the pressure swing adsorption is compressed and fed to the reformer (4) on the inlet side together with the DME.

7. A method according to claim 5 or 6, characterized in that the CO2 separation is carried out by a condensation process or includes such a process, preferably, wherein the cold required for the condensation of the CO2 provided by an open or closed refrigeration circuit containing DME as refrigerant.

8. Method according to one of the preceding claims, characterized in that a reformer (4) designed as a steam reformer is used, wherein the steam reforming is carried out in particular at a reformer outlet temperature in the range from 750°C to 950°C, preferably 775°C to 950°C.

9. The method according to claim 8, characterized in that a fired, in particular gas-fired, steam reformer with a burner is used, in particular wherein the flue gas is partially condensed, in particular wherein heat integration of the flue gas takes place and the partial condensation of the flue gas takes place in a final stage of heat integration, and / or wherein the condensation enthalpy is used to heat DME, the combustion air and / or water.

10. A method according to any one of claims 5 to 7 and claim 9, characterized in that gas originating from the CO2 capture process is fed to the burner and used as fuel for the burner.

11. A method according to claim 9 or 10, characterized in that a portion of the hydrogen produced is fed to the burner and used as fuel for the burner.

12. A method according to claim 6 and claim 11, characterized in that the hydrogen is removed after the hydrogen purification and fed to the burner.

13. The method according to any one of claims 1 to 7, characterized in that a reformer (4) designed as an autothermal reformer is used, wherein the autothermal reforming is preferably carried out at a reformer outlet temperature in the range from 950°C to 1050°C.

14. The method according to any one of the preceding claims, characterized in that a gas-heated additional reformer is used, wherein synthesis gas obtained in the reformer (4) is supplied to the additional reformer for heating thereof, preferably wherein the additional reformer is connected upstream of the reformer (4) or in parallel with the reformer (4), and / or wherein the additional reformer is designed as a steam reformer.

15. The method according to any one of the preceding claims, characterized in that an adiabatic pre-reformer is used upstream of the reformer (4), preferably wherein the pre-reformer comprises an acidic catalyst material or a Ni-based catalyst material with a higher Ni loading than the catalyst material of the reformer (4).

16. Process according to one of the preceding claims, characterized in that the synthesis gas obtained by reforming is cooled.

17. Process according to one of the preceding claims, characterized in that the synthesis gas obtained by the reforming is subjected to a water gas shift reaction, preferably after cooling.

18. Process according to one of claims 5, 6, 7 or 10 and claim 17, characterized in that the CO2 separation is carried out after the water gas shift reaction.

19. Method according to one of the preceding claims, characterized in that the DME is supplied in liquid form and is evaporated before entering the reformer (4), preferably wherein a thermal energy storage device is used to provide the energy required for the evaporation during a start-up phase, and / or wherein the evaporated DME, in particular mixed with steam, is superheated before entering the reformer (4).

20. Process according to claims 16 and 19, characterized in that, in particular after a start-up phase, the liquid DME is used for cooling the synthesis gas, preferably, wherein the synthesis gas obtained by the reforming and the liquid DME are passed through a common heat exchanger in which the synthesis gas is cooled and the liquid DME is evaporated.

21. A process according to any one of the preceding claims, characterized in that no combustion of a purge stream takes place.

22. Plant for producing hydrogen from DME (dimethyl ether) in a process according to one of the preceding claims, with a reformer (4), characterized in that the reformer (4) is designed to carry out a reforming of DME at a pressure in the range from 15 bar to 70 bar, preferably in the range from 20 bar to 40 bar, and at a reformer outlet temperature in the range from 750°C to 1050°C, preferably in the range from 750°C to 950°C, and the reformer (4) comprises a nickel- or cobalt-based catalyst material, and in that a DME evaporation device (1) is provided upstream of the reformer (4).

23. Plant according to claim 22, characterized in that the reformer (4) comprises a catalyst bed with at least two layers, wherein at least one layer comprises or consists of an acidic catalyst material, in particular gamma-alumina, and at least one further layer comprises or consists of a nickel- and / or cobalt-based catalyst material, or wherein two layers comprise or consist of a nickel-based catalyst material.

24. Plant according to claim 22 or 23, characterized in that the reformer (4) has a catalyst bed comprising a first and a second region, wherein the first region has a first catalyst material and the second region has a second catalyst material different from the first catalyst material, and wherein the catalyst bed is designed and arranged in a reformer (4) used for the reforming process such that the first and the second region are successively flowed through during operation by the DME and / or by a product resulting from the DME during the reforming process, preferably wherein the first catalyst material is an acidic catalyst material and the second catalyst material is a nickel- or cobalt-based catalyst material, and / or wherein the first region is arranged upstream of the second region, and / orwherein the reformer (4) has a preferably vertically arranged reformer tube in which the catalyst bed is arranged., 25. Plant according to one of claims 22 to 24, characterized in that the catalyst bed comprises a catalyst bed or is provided by such a bed.

26. Plant according to one of claims 22 to 25, characterized in that downstream of the reformer (4) there is a A CO2 separation device (7) is provided to separate carbon dioxide (CO2) from the synthesis gas obtained by the reforming, preferably, wherein the CO2 separation device (7) is designed for CO2 separation by chemical scrubbing, in particular amine scrubbing in one or two stages, and / or by physical scrubbing, in particular based on methanol and / or DME, and / or by a membrane process and / or by an adsorption process, and / or that the CO2 separation device (7) is designed to ensure a CO2 separation rate of at least 55%, preferably a CO2 separation rate in the range from 80% to 99%.

27. Plant according to claim 26, characterized in that the CO2 separation device (7) is designed for CO2 separation by a condensation process, preferably, wherein the CO2 separation device (7) is designed to provide the cold required for condensing the CO2 by means of an open or closed refrigeration circuit containing DME as a coolant.

28. Plant according to claim 26 or 27, characterized in that the reformer (4) is designed as a steam reformer, in particular, wherein the reformer (4) is designed as a fired steam reformer with a burner, preferably, wherein a condensation device is provided for the partial condensation of the flue gas, in particular in a final stage of a flue gas heat integration.

29. Plant according to claims 27 and 28, characterized in that at least one connecting line is provided connecting the CO2 separation device (7) and the burner, via which a gas originating from the CO2 separation device (7) can be led to the burner.

30. Plant according to one of claims 22 to 27, characterized in that the reformer (4) is designed as an autothermal reformer.

31. Plant according to one of claims 22 to 30, characterized in that a gas-heated additional reformer is provided, wherein the additional reformer can be heated by means of synthesis gas obtained in the reformer (4), preferably wherein the additional reformer is connected upstream of the reformer (4) or in parallel with the reformer (4), and / or wherein the additional reformer is designed as a steam reformer.

32. Plant according to one of claims 22 to 31, characterized in that an adiabatic pre-reformer (4b) is provided upstream of the reformer (4), preferably, wherein the pre-reformer comprises an acidic catalyst material or a Ni-based catalyst material with a higher Ni loading than the catalyst material of the reformer (4).

33. Plant according to one of claims 22 to 32, characterized in that a cooling device (5) for cooling synthesis gas obtained by steam reforming is provided downstream of the reformer (4), preferably, wherein the cooling device (5) comprises a heat exchanger or is formed by such a heat exchanger and the heat exchanger has at least one line for synthesis gas and at least one line for DME.

34. Plant according to one of claims 22 to 33, characterized in that a water gas shift reactor (6) is provided downstream of the reformer (4).

35. Plant according to one of claims 22 to 34, characterized in that downstream of the reformer (4) there is a water substance purification device (8) is provided, wherein the hydrogen purification device (8) comprises at least one pressure swing adsorption reactor and / or wherein a connecting line connecting the hydrogen purification device (8) and the reformer (4), via which line a gas originating from the hydrogen purification device (8), which preferably comprises H2 and CH4 and CO, in particular a tail gas of the pressure swing adsorption, can be supplied to the reformer (4) on the inlet side, in particular together with the DME, and a compressor for compressing the gas originating from the hydrogen purification device (8) are provided.

36. Plant according to claims 28 and 35, characterized in that the reformer (4) has a burner and at least one connecting line is provided connecting the hydrogen purification device and the burner, via which a gas originating from the hydrogen purification device (8) can be led to the burner.

37. Plant according to one of claims 22 to 36, characterized in that a thermal energy storage device is provided via which the DME evaporation device (1) can be fed.

38. Plant according to one of claims 22 to 37, characterized in that a preferably electrically powered superheating device (3) is provided upstream of the reformer (4), in particular, the superheating device (3) is connected downstream of the DME evaporation device (1).

39. Plant according to one of claims 22 to 38, characterized in that a steam generation unit is arranged upstream of the reformer (4). device (2) is provided, wherein the steam generating device (2) can be fed via a thermal energy storage device.

40. System according to claim 38 and claim 39, characterized in that the superheating device (3) is connected on the inlet side to an outlet of the DME evaporation device (1) and to an outlet of the steam generating device (2) in order to be able to superheat a mixture of evaporated DME and steam.

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