Substrate monolith including a reforming catalyst

Abstract

The present invention is directed to a catalyst body in the form of a substrate monolith and to an apparatus for reforming, especially in an adiabatic manner, of hydrocarbons, especially methane from natural gas. Said catalyst body has precious metals and a support oxide for the precious metals. Likewise claimed are a process for production thereof and the use thereof for production of hydrogen. The precious metals are selected from platinum, palladium and rhodium, and the molar M1 / M2 ratio in the inlet region of the substrate monolith is higher than at the other end, where M1 is Pt and / or Pd and M2 is Rh.

Description

[0001] Substrate monolith comprising a reforming catalyst

[0002] Description

[0003] The present invention is directed to a catalyst body in the form of a substrate monolith and a device for, in particular, the adiabatic reforming of hydrocarbons, in particular methane from natural gas. This reforming catalyst contains noble metals and a carrier oxide for the noble metals. A process for its production and its use in the production of hydrogen are also claimed.

[0004] Low-emission mobility and power generation will play an increasingly important role in the future. One way to achieve this is to use hydrogen as an energy carrier. There are many approaches to this. One problem in this context is the production and storage of hydrogen. Hydrogen is highly volatile and, as the lightest chemical element, can only be liquefied or stored under extreme conditions.

[0005] Therefore, there is an increasing search for solutions to produce hydrogen where it is needed. One approach to producing hydrogen in situ is the conversion of hydrocarbons, such as natural gas, using a reforming catalyst at elevated temperatures. Hydrocarbons and natural gas are comparatively easy to store and, thanks to existing infrastructure, are available almost everywhere. This hydrogen can then be converted into electricity in a fuel cell, for example, which can be used for transportation or stationary applications.

[0006] Corresponding processes and catalysts for reforming are known to the person skilled in the art (e.g. WO201103338A2, WG2003104143A1 , US2013079217AA,

[0007] US2009283419AA, US2008219918AA, EP2251080A1). WG2005056179A1 specifies catalysts for the reforming of hydrocarbons to produce hydrogen, which contain precious metals and carrier oxides. Among other things, carrier oxides based on aluminum oxide, magnesium oxide, and cerium oxide are proposed here. The aluminum oxide can be added to the carrier oxide in the form of a spinel with magnesium. Further addition of aluminum oxide and the addition of cerium oxide complete the structure of the carrier oxide. Despite the large number of proposals for corresponding catalysts, the task still remains to specify further, improved catalysts for the reforming of hydrocarbons. These catalysts should exhibit sufficient stability and activity to generate hydrogen under the most efficient conditions possible.Furthermore, a suitable catalyst should be highly robust and durable, as well as being as cost-effective as possible. The sharp rise in the price of rhodium, in particular, requires further optimization of such catalysts, including with regard to their activity. Against this backdrop, substitution with platinum could help. Although less active in steam reforming of methane, for example, it can be used more advantageously due to its significantly lower price.

[0008] These and other problems arising from the prior art are solved by a substrate monolith having the features of the present claim 1. Claims 2-6 relate to preferred embodiments of the catalyst according to the invention. Claim 7 is directed to a device for power generation, and claim 8 to a method for producing the corresponding catalysts. Claims 9-12 are directed to suitable uses of the same.

[0009] By specifying a substrate monolith comprising a reforming catalyst for producing hydrogen from hydrocarbons, in particular methane, comprising precious metals and at least one carrier oxide on which the precious metals are deposited, wherein the precious metals are selected from the group consisting of Pt, Pd and Rh and M1 / M2 is larger at the inlet region of the substrate monolith than at the other end, where M1 = Pt and / or Pd and M2 = Rh, the posed problem is solved very simply, but no less surprisingly. M1 and M2 describe the molar amounts of Pt and / or Pd and Rh in the substrate monolith. These are measured, for example, once at the front in the inlet region (5 mm from the beginning of the substrate monolith in the direction of flow) and once in the outlet region (5 mm from the end of the substrate monolith against the direction of flow).The entrance area of ​​the substrate monolith is the area that first comes into contact with the incoming gas.

[0010] The inventive substrate monolith with a reforming catalyst presented here exhibits extremely advantageous activity compared to prior art examples. The asymmetric distribution of the precious metals according to the present invention results in a catalyst that, on the one hand, exhibits good activity and, on the other hand, is optimized with regard to the use of expensive precious metals. In particular, the zoned architecture allows for a simple production-technological design of the invention with regard to the distribution of the precious metals. Furthermore, the catalyst is very robust against changing ambient conditions and exhibits exceptional long-term stability (see Table 2). This was not expected on the priority date.

[0011] The reforming catalyst according to the invention is surprisingly simple in design. It advantageously consists of precious metals deposited on a carrier oxide, in particular Pt and Rh, or only Pt or Rh, optionally in appropriate zones or with appropriate concentration gradients. It has proven advantageous if the precious metals, in particular Pt and Rh, are deposited together on the oxides. In this case, "deposited together" means that no differentiation is made with regard to the oxides, such that, for example, Rh is deposited only on cerium oxide and Pt only on aluminum oxide. It is possible that the possible alloying of the precious metals, particularly Pt and Rh, promotes strong hydrogen production (CH4 + 2 H2O -> 4 H2 + CO2) during joint deposition.

[0012] Within the scope of the invention, all materials familiar to the person skilled in the art for this purpose, such as Al2O3, CeO2, ZrO2, TiO2, La2O3, BaO, SnO2, ZnO, MgO, HfO2, and MnO2, as well as mixtures or mixed oxides thereof, are considered as constituents of the carrier oxide. Optionally doped mixed oxides (e.g., cerium-zirconium mixed oxides) can also be used in this case. Physical mixtures comprising aluminum oxide, cerium oxide, and / or spinel (MgAhO4; https: / / de.Wikipedia.org / w / index.php?title=Spinell&oldid=224329096) are advantageously used in this case. The composition of the carrier oxide can vary. Preferably, aluminum oxide, cerium oxide, and spinel are exclusively present as the carrier oxide. Possible compositions can be obtained as desired through physical mixtures, wherein preferably at least all three components can be included. Other preferred mixtures are between 5 MgAhC + CeC>2 + 1.7 AI2O3 and 20 MgAhC + CeC>2 + 6.9 AI2O3.The composition 8-9 MgAhC + CeC>2 + 2-4 Al2O3 is particularly preferred. Suitable carrier oxides can also be found in the prior art mentioned above.

[0013] Particularly suitable aluminum oxides in this context are selected from the series consisting of aluminum oxide and doped aluminum oxide. Doped aluminum oxides are, for example, aluminum oxides doped with lanthanum oxide, zirconium oxide, silicon oxide, cerium oxide, barium oxide, and / or titanium oxide. Aluminum oxide, La- or cerium-doped aluminum oxide is advantageously used, with lanthanum being used in amounts of, in particular, 1 to 10 wt. %, preferably 3 to 6 wt. %, each calculated as La2O3 and based on the weight of the stabilized aluminum oxide. Even in the case of barium oxide-doped aluminum oxide, the proportion of barium oxide is, in particular, 1 to 10 wt. %, preferably 3 to 6 wt. %, each calculated as BaO and based on the weight of the stabilized aluminum oxide. A particularly suitable aluminum oxide is lanthanum-stabilized aluminum oxide, which may also be doped with cerium oxide, barium oxide, and / or strontium oxide.The carrier oxide preferably comprises at least one aluminum oxide or doped aluminum oxide. In this context, γ-aluminum oxide or La-stabilized γ-aluminum oxide with a BET surface area of ​​30 to 250 m² is particularly preferred. 2 / g, preferably from 100 to 200 m 2 / g (determined according to DIN 66132 - latest version on the filing date). Such active aluminum oxide is widely described in the literature and, as mentioned, is commercially available (e.g., from Sasol®). Very preferred is an aluminum oxide or doped aluminum oxide with a particle size distribution of d50 - value of < 100 pm, preferably < 70 pm, and very preferably < 50 pm (Q3 distribution, ISO 13320-1 - latest version on the filing date).

[0014] The carrier oxide preferably comprises at least one high-surface-area and temperature-stable cerium oxide (e.g., EP1435338A1), which can also be purchased commercially (e.g., from Solvay®). Cerium oxide is used in amounts of 1 to 20 wt.%, preferably 8 to 12 wt.%, in the carrier oxide.

[0015] As a third component, the carrier oxide preferably contains at least one spinel of the MgAhO4 type. This is particularly preferably used as the main component in amounts of 50 to 90 wt.%, preferably 60 to 80 wt.%, in the carrier oxide. This can be produced in-house (e.g., DE1571299B2; https: / / de.wikipedia.org / w / index.php?title=Spi- nelle&oldid=225306698) or obtained commercially. The remainder of the carrier oxide is then preferably only the above-mentioned aluminum oxide.

[0016] It is particularly advantageous that the present reforming catalyst contains only the components mentioned above. In particular, it does not require any additional transition metals or transition metal oxides. Advantageously, the present catalyst does not contain elements selected from the group consisting of zirconium, chromium, and nickel.

[0017] The reforming catalyst is generally present as a normal coating on the substrate monolith. Therefore, the embodiment in which the reforming catalyst according to the invention comprises additional binders is advantageous in this regard. Suitable binders include, for example, non-catalytically active, or only slightly catalytically active, temperature-stable metal oxides, such as SiO2, Al2O3, and ZrO2. Those skilled in the art will know which materials are suitable here. The proportion of such binders in the reforming catalyst can, for example, amount to up to 10 wt.%, preferably up to 5 wt.%, of the total mass of the reforming catalyst. Binders are suitable for ensuring stronger adhesion of the coating to a support. For this purpose, a specific particle size of the metal oxides in the binder is advantageous. This can be adjusted by the skilled person according to their requirements. For example,The addition of sols of the above-mentioned elements to the coating suspension has proven particularly advantageous. An aluminum sol, such as Nyacol® or boehmite (https: / / de.wi kipedia.org / w / index.php?title=B%C3%B6hmit&oldid=226104395), is particularly advantageous in this context.

[0018] The reforming catalyst comprises noble metals, in particular Pt and Rh, deposited on a support oxide. Preferably, only Pt and Rh are used. The molar ratio of Pt to Rh in the substrate monolith is preferably 1:2 to 8:1, more preferably 1:1 to 5:1, and most preferably 2:1 to 3:1. It is also possible for no Pt and only Rh, or Pt and no Rh, to be present in corresponding zones (e.g., Fig. 1 c).

[0019] In the present case, the ratio M1 / M2 varies according to the invention over the length of the substrate monolith. Pt and / or Pd are always present at the front (5 mm from the entrance into the substrate monolith). Particularly preferably, a zone is located in the entrance area of ​​the substrate monolith, which in particular contains Pt and has a higher M1 / M2 ratio than a zone positioned in the exit area of ​​the substrate monolith. The entrance area of ​​the substrate monolith comes into contact with the inflowing gas first. The reforming reaction taking place across the entire substrate monolith is highly endothermic. This means that the temperature in the exit area is significantly lower than in the entrance area. The substrate monolith must therefore be able to withstand a large temperature gradient typical of it.For this purpose, advantageous values ​​for M1 / M2 for the front (5 mm from the entrance of the substrate monolith) and the rear (5 mm from the end of the substrate monolith) are given in the following Table 1:.

[0020] Table 1 :

[0021] The present invention relates to a substrate monolith comprising a reforming catalyst. The latter can be applied to a substrate monolith, preferably to a flow-through substrate, by a coating step familiar to those skilled in the art (DE102019100099A1 and the literature cited therein). A filter substrate such as a wall-flow filter is also possible in this context. Flow-through substrates are substrate monoliths commonly used in the art and can consist of metal (e.g., WO17153239A1, WO16057285A1, WO15121910A1 and the literature cited therein) or ceramic materials. Corrugated substrates can also be considered flow-through substrates. These are known to those skilled in the art as supports made of corrugated sheets made of inert materials. Suitable inert materials are, for example, fibrous materials with an average fiber diameter of 50 to 250 pm and an average fiber length of 2 to 30 mm.Fibrous heat-resistant materials made of silicon dioxide, especially glass fibers, are preferred. However, refractory ceramics such as cordierite, silicon carbide, or aluminum titanate, etc., are preferred as honeycomb supports. The number of channels in these supports per unit area is characterized by the cell density, which is typically between 300 and 900 cells per square inch (cpsi). The wall thickness of the channel walls for ceramics is between 0.5 and 0.05 mm.

[0022] The absolute length of the inventive substrate monoliths containing the reforming catalysts can also be adjusted by the skilled person and adapted to their needs. A length of 5.0–16.0 cm, preferably 6.0–14.0 cm, and very preferably 7.0–13.0 cm has proven advantageous for the present application. The total amount of coatings in the substrate monolith is selected so that the inventive catalyst is used as efficiently as possible. In the case of a flow-through substrate, for example, the total amount of reforming catalyst in the coatings (solids content) per support volume (total volume of the support) can be between 100 and 300 g / L, in particular between 120 and 250 g / L. The total precious metal content of the substrate monolith is preferably from 0.015 - 5 g / L, more preferably from 1.0 - 3.0 g / L and particularly preferably from 1.6 - 2.2 g / L carrier volume.If platinum or palladium is used, it should be present in the coating in a range of 0.5 - 2.5 g / L, more preferably 1.3 - 1.9 g / L carrier volume. Rhodium is present in the reforming catalyst in an amount of 0.1 - 1.0 g / L, more preferably 0.3 - 0.4 g / L carrier volume in the respective component.

[0023] In a further preferred embodiment, the substrate monolith discussed here has a particularly advantageous design for the present application. In this case, a zoned design is particularly suitable. A zoned embodiment is preferred, as shown by way of example in Fig. 1. The substrate monolith is particularly preferably constructed in such a way that it has a coating zone comprising Pt on the carrier oxide on the upstream side and a coating zone with a metal mixture comprising Pt and Rh on the carrier oxide on the downstream side. It can also be advantageous if both zones contain Pt and Rh, and the front zone has a higher concentration of Pt and the rear zone has a higher concentration of Rh. It is surprisingly advantageous to mix Pt and Rh for the most efficient methane reforming possible before introduction into the washcoat if, within the scope of the invention, they occur together in one zone or together in the entire substrate monolith (e.g.Fig. 2). Those skilled in the art will know how to proceed in this regard. It is also possible to locate the zones on different flow-through substrates connected directly one after the other. Upstream means that this zone comes into contact with the medium to be converted first, before the other one. Downstream is to be understood accordingly.

[0024] The corresponding coating on the substrate monolith is used in an amount of 15 to 200 g / L, in particular between 100 and 200 g / L, particularly preferably approximately 120-180 g / L of total carrier volume. The total precious metal content in the coating can be in the range of 0.01-3.0 g / L, more preferably 1.65-2.15 g / L of total carrier volume. Rh is advantageously present in the corresponding zone(s) at contents of preferably 0.07-0.5 g / L, particularly 0.1-0.35 g / L. The platinum content in the corresponding zone(s) is preferably also 0.07-2.0 g / L, more preferably 0.5-1.3 g / L of total carrier volume.

[0025] Depending on the gas composition and temperature profile of the catalyst, Pt may be present in addition to Rh in the downstream zone. This preferably contains Pt:Rh in a molar ratio of 1:1, but can have other ratios of 3:1 to 1:2 depending on the gas composition and temperature profile of the catalyst. It may also be advantageous to use only rhodium as the precious metal in this zone.

[0026] As already indicated, the preferred zones are located on one substrate monolith. It is also possible for them to be located on two substrate monoliths, which are then arranged directly one behind the other. The zone lengths can be selected by the person skilled in the art. It has proven advantageous if the upstream zone in the catalyst according to the invention is shorter than the downstream zone due to the sharp temperature drop in the catalyst. The ratio of the zone lengths is preferably between 50 / 50 - 30 / 70 and more preferably around 40 / 60 - 30 / 70.

[0027] The present invention also relates to a device for generating electricity, comprising a substrate monolith as just outlined and a fuel cell in fluid contact with the substrate monolith. Such devices and their design are known in principle to those skilled in the art (e.g., JP2008007359 (A), CN111029628). The hydrogen produced on the substrate monolith over the reforming catalyst according to the invention is brought into contact with the anode of the fuel cell via a fluid connection. It is then converted into hydrogen ions, which oxidize with atmospheric oxygen at the cathode to form H2O, which can be released into the ambient air.

[0028] The present invention further provides a process for producing a corresponding reforming catalyst substrate, in which the substrate monolith is coated with a coating suspension comprising the components of the reforming catalyst according to the invention in water, then dried and calcined and finally tempered at a temperature of 500 - 600°C for a maximum of 2 hours.

[0029] In a first step, a coating suspension is preferably prepared from the carrier oxide components and, if appropriate, binders in water. This suspension is then mixed with solutions of water-soluble precious metal compounds, in particular Rh compounds and, if appropriate, Pt compounds. The precious metals are thus deposited together, preferably by mixing and subsequent injection, onto the entire carrier oxide. Separate preparation of the oxides containing precious metals and their subsequent blending is also possible. The preparation of corresponding suspensions for coating substrates is well known to those skilled in the art from the field of automotive exhaust catalyst production (e.g., DE202016008848A1).

[0030] This suspension is then applied to a substrate monolith, in particular a flow-through substrate. These procedures are also familiar to those skilled in the art, for example from the field of automotive exhaust catalysts (e.g. W02020141188A1 and the literature cited therein). The zones can be coated using methods familiar to those skilled in the art (e.g. EP1273344A1, EP2533901A1). The coated substrate monolith is then dried and calcined, if necessary. It has proven advantageous if the coated substrate monolith is subsequently tempered at a somewhat higher temperature in order to completely expel organic constituents from the coating, for example in the form of CO2 or NOx. This also makes it possible to establish a mass balance based on oxides.

[0031] It is particularly advantageous if the coated substrate monolith is dried at 100-150°C, preferably 110-130°C. The calcination temperature should not be too high. It is preferably between 300°C and a maximum of 500°C, preferably between 320°C and 400°C. The catalyst is then tempered for preferably a maximum of 6 hours, more preferably a maximum of 4 hours, and particularly preferably for up to 3 or 2 hours at a temperature of 400-600°C, preferably 520-580°C. The reforming catalyst on the substrate monolith is then ready for installation in the device according to the invention.

[0032] The present invention also relates to the use of a substrate monolith according to the invention comprising a reforming catalyst for generating hydrogen from hydrocarbons, in particular methane. Methane is the most stable hydrocarbon and is comparatively difficult to convert catalytically. However, it forms the main constituent of natural gas. The reforming catalyst according to the invention is capable of adequately converting methane. The conversion preferably takes place adiabatically at temperatures of 300-900 °C, preferably 650-800 °C, in an atmosphere consisting preferably of methane, water vapor, and, through possible exhaust gas recirculation, additionally CO, CO2, and H2. Preference is given to using the hydrogen produced from natural gas (CNG, LNG).

[0033] The substrate monolith according to the invention is used for the reforming of hydrocarbons. It generates a surprisingly large amount of hydrogen when hydrocarbons, in particular methane, are passed over it at elevated temperatures. Since the reactions taking place are endothermic, it is advantageous to minimize heat loss to the environment through insulation as much as possible in order to keep heat loss as small as possible. Therefore, it is advantageous for the use according to the invention if this use takes place under adiabatic conditions, i.e. there is little to no heat exchange in either direction, with or from the environment. The use should preferably be designed such that the heat exchange with the environment is between zero and 15%, preferably less than 10%, and very preferably less than 5%, based on the amount of heat supplied in the form of the heated reaction gases via the substrate monolith.The specialist knows how to insulate the substrate monolith from the environment in order to achieve these values.

[0034] In a further preferred application, the hydrogen thus produced is used to generate electricity in a fuel cell. Further preferred applications according to the invention can be found in both mobile (vehicles) and stationary (industrial plants) applications.

[0035] By coating, for example, a cordierite flow-through substrate with a Rh-containing and Pt and / or Pd-containing coating medium deposited on the corresponding carrier oxides, followed by thermal treatment, a reforming catalyst substrate is produced that generates hydrogen from hydrocarbons, particularly methane, in a highly water-containing and oxygen-free reaction atmosphere at elevated temperatures. A particularly active arrangement is one in which the precious metals are selected from the group consisting of Pt, Pd, and Rh, and M1 / M2 at the catalyst inlet is larger than at the outlet, where M1 = Pt and / or Pd and M2 = Rh. This achieves an optimal balance between sufficient activity and the lowest possible precious metal price.

[0036] The reforming catalyst is long-term stable and, with a targeted continuous operation of over 50,000 hours and under very harsh conditions, remains sufficiently active even toward the end of its service life to produce the required amount of hydrogen. Due to the endothermic reaction, a very strong temperature gradient exists within the reforming catalyst, which can reach up to 200 °C under the targeted application parameters. The reforming catalyst according to the invention meets these requirements.

[0037] Figures:

[0038] Fig. 1: Preferred layout of the reforming catalyst according to the invention with the individual zones.

[0039] Fig. 2: Further conceivable embodiments of the reforming catalyst according to the invention: Mixture of Pt and Rh over the entire substrate monolith, wherein the M1 / M2 ratio is varied according to the invention.

[0040] Examples:

[0041] To manufacture the catalysts, cordierite substrates from NGK (4.66" x 4.66" x 5.00", 4.3 / 300) are coated with a washcoat. Other flow-through substrates, particularly those with different cell densities and wall thicknesses and also made of cordierite (e.g., 5.66" x 5.66" x 5.00", 4 / 400), are also possible. Metallic substrates can also be used. The catalytic activity is not substrate-dependent.

[0042] To prepare the washcoat, the carrier oxide (Puralox® SCFa 110 from Sasol) and the AlO(OH) binder (Nyacol® AL20 from Nyacol) are first dispersed successively in water. The precious metal solutions are then injected. For the catalyst zones containing both precious metals, the platinum nitrate and rhodium nitrate solutions are mixed and diluted with water prior to injection. After 30 minutes of stirring, the pH is adjusted to > 7, and the washcoat is circularly ground. The target particle size distribution is a d50 value of 4.5–5.5 pm and a d50 value of 10.6–14.8 pm.

[0043] Depending on the oxide-based solids content, which is ideally 33 - 36%, and the rheology of the washcoat, it can be adjusted using nitric acid (HNO3), tetraethylammonium hydroxide (TEAH) or acetic acid (HCOOH) to facilitate coatability.

[0044] Finally, the substrate is clamped vertically in a holding device, and the washcoat is pumped into the substrate from below to the desired height and then vacuumed out again. By weighing after a drying and calcining step, any remaining mass is determined and recoated if necessary.

[0045] In an alternative coating process, the washcoat is applied to the vertically aligned substrate. By applying negative pressure, it is then sucked through the substrate. By weighing after a drying and calcination step, any remaining mass is determined and then recoated from the other side. In addition to this coating process, the required washcoat can also be determined before coating and sucked into the substrate from each side in two steps, half according to the zones that may be present. The final step is the thermal treatment of the catalyst. After drying at 100 - 120 °C and calcination at 350 °C for approximately 15 minutes after each coating step, it is then annealed at 550 °C for 2 hours.

[0046] The following substrate monoliths were produced:

[0047] Example 1 - Inlet: 18.48 g / ft 3 Pt (1 :0) Outlet: 18.52 g / ft3 Pt, 9.77 g / ft 3 (1 :1)

[0048] Example 2 - Inlet: 23.74 g / ft 3 Pt, 2.77 g / ft 3 Rh (4.52:1) Outlet: 13.26 g / ft 3 Pt, 7.0 g / ft 3 Rh (1:1)

[0049] Example 3 - Inlet: 2.0 g / ft 3 Pt, 5.0 g / ft 3 Rh (0.21 :1) Outlet: 35 g / ft 3 Pt, 4.77 g / ft 3 Rh (3.87:1)

[0050] Example 4 - Homogeneous coated: 37 g / ft 3 Pt, 9.77 g / ft 3 Rh (2:1)

[0051] All zoned examples are zoned 30 / 70.

[0052] For testing, 1" x 3" cores are taken from the coated catalyst and tested for their methane conversion in an adiabatic quartz glass reactor.

[0053] The reaction gas mixture primarily tested consists of 5.9% CH4, 21.9% H2O, 1.8% CO, 12.9% CO2, 7.5% H2, and N2 for balance at a space velocity of 25,000 l / h. The measurement begins at a gas temperature of 150 °C. Heating is carried out at a rate of 10 K / min up to 700 °C. Once this maximum temperature is reached, it is held constant for 30 minutes, after which the measurement ends. Finally, the gas is cooled in the reaction gas atmosphere to 450 °C and then to room temperature in air.

[0054] The methane conversion, which is a measure of the activity of the catalyst, is calculated from the methane input concentration before methane conversion and the concentration at maximum reactor temperature.

[0055] In addition to testing fresh catalysts, simulation of catalyst aging is necessary to evaluate long-term stability and activity. For this purpose, the prepared catalyst cores were aged for approximately 50 hours at 850 °C in a flowing atmosphere of forming gas (3.3% H2, N2) and 44% H2O. The decrease in catalytic activity after aging is a measure of the long-term stability and activity of the catalysts. Measurement results (Table 2: Tested catalysts with Pt:Rh = 2:1)

[0056] Catalyst name / M1 / M2 Methane conversion Molar Pt:Rh-

[0057] Parameter front rear* at Tm = 700 °C / % Ratio Architecture

[0058] Example 1 fresh . 27.12 _ . According to

[0059] Example 2 fresh 25.35 ". According to

[0060] 4 52 - 1 2:1 ,

[0061] Example 2 aged ' 22.96 big. l . b)

[0062] Example 3** fresh 24.67 . According to Example 3** aged 22.86 r| G- 1 ■

[0063] Example 4** fresh 23.77 According to

[0064] Example 4** aged 23.08 Fig. 2

[0065] *front is 5mm from the entrance of the substrate monolith; back is 5mm from the end of the

[0066] Substrate monoliths removed; ** Reference examples. As can be seen in the table above, the architecture shown in Fig. 1 a) with a Pt:Rh ratio of 2:1 results in the highest methane conversion before and after aging (Example 1). In general, methane conversion increases with increasing platinum content in the inlet region. The seemingly low methane conversion at first glance is due to the fact that only small drill cores and no full catalysts were tested, while the amount of reaction gases corresponded to approximately half the intended gas volume to be passed through a full catalyst.

Claims

Patent claims 1 . Substrate monolith comprising a reforming catalyst for producing hydrogen from hydrocarbons, in particular methane, comprising noble metals and at least one carrier oxide on which the noble metals are deposited, characterized in that the noble metals are selected from the group consisting of Pt, Pd and Rh and M1 / M2 is larger at the inlet region of the substrate monolith than at the other end, where M1 = Pt and / or Pd and M2 = Rh.

2. Substrate monolith according to claim 1, characterized in that the carrier oxide comprises a MgAhC spinel as well as CeC>2 and AI2O3.

3. Substrate monolith according to claim 1 or 2, characterized in that it does not contain any elements selected from the group consisting of zirconium, chromium and nickel.

4. Substrate monolith according to claim 1, 2 or 3, characterized in that it comprises a binder.

5. Substrate monolith according to one of claims 1 - 4, characterized in that the molar ratio of Pt to Rh is 1:2 to 8:

1.

6. Substrate monolith according to claim 5, characterized in that it has at least 2 zones and both zones contain Pt and Rh and the front zone contains a higher concentration of Pt and the rear zone contains a higher concentration of Rh.

7. A device for generating electricity comprising a substrate monolith according to claim 1 - 6 and a fuel cell in fluid contact therewith.

8. A process for producing a substrate monolith of claims 1-6, characterized in that the substrate monolith is coated with a coating suspension comprising the components of the reforming catalyst in water, then dried and / or calcined and finally tempered at a temperature of 400-600°C for a maximum of 6 hours.

9. Use of a substrate monolith according to any one of claims 1-6 for producing hydrogen from hydrocarbons.

10. Use according to claim 9, characterized in that it takes place under adiabatic conditions.

11. Use of a catalyst according to claim 9 or 10, characterized in that the hydrogen is produced from natural gas (CNG, LNG).

12. Use according to one of claims 9 to 11, characterized in that the hydrogen produced is used to generate electricity in a fuel cell.

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