Exhaust gas cleaning device, method

Abstract

The invention relates to an exhaust gas purification device, which is at least configured to direct an exhaust gas stream (10a; 10b; 10c; 10d), with at least one catalyst element (12a; 12b; 12c; 12d) arranged in the exhaust gas stream (10a; 10b; 10c; 10d), which has at least one catalyst material, and which is configured to oxidize at least one exhaust gas component of the exhaust gas components contained in the exhaust gas stream (10a; 10b; 10c; 10d) at least substantially. At least one chromium protection element (14a; 14b; 14c; 14d) is proposed, which is arranged in the exhaust gas stream (10a; 10b; 10c; 10d), which has at least one chromium protection material, and which is designed to bind chromium components, preferably chromium(VI) oxide, from the exhaust gas stream (10a; 10b; 10c; 10d).

Description

State of the art

[0001] An exhaust gas flow purification device has already been proposed which is at least designed to conduct an exhaust gas flow, with at least one catalyst element arranged in the exhaust gas flow, which catalyst element has at least one catalyst material and which is designed to at least substantially oxidise at least one exhaust gas component of the exhaust gas components contained in the exhaust gas flow. Disclosure of the invention

[0002] The invention is based on an exhaust gas flow purification device which is at least designed to conduct an exhaust gas flow, with at least one catalyst element arranged in the exhaust gas flow, which catalyst element has at least one catalyst material, and which is designed to at least substantially oxidize at least one exhaust gas component of the exhaust gas components contained in the exhaust gas flow.

[0003] At least one chromium protection element is proposed which is arranged in the exhaust gas stream, which comprises at least one chromium protection material, and which is designed to bind chromium components, preferably chromium(VI) oxide, from the exhaust gas stream.

[0004] The inventive design of the exhaust stream purification device advantageously provides a long service life, since in particular the chromium protective element binds the chromium components from the exhaust stream and thereby prevents a reduction in catalytic performance, such as clogging of the catalyst element. Advantageously, high operational safety / reliability can be provided, since in particular the chromium protective element prevents a reduction in catalytic performance, such as clogging of the catalyst element, and thus ensures a high exhaust stream purification performance of the catalyst element. Advantageously, a low-cost design can be provided, since in particular the chromium protective element requires less catalyst material.Advantageously, a high level of environmental protection can be provided, since in particular the chromium protective element binds the chromium components in the exhaust gas stream and the chromium components are not emitted into the environment.

[0005] The exhaust gas purification device is preferably configured for an SOFC (Solid Oxide Fuel Cell) fuel cell. Alternatively, however, the exhaust gas purification device is also configured for exhaust gas aftertreatment of any chemical processes, such as combustion processes, which preferably contain chromium components and / or carbon monoxide. The exhaust gas purification device preferably comprises at least one base body comprising the catalyst material and / or the chromium protective material. The base body is preferably formed from a ceramic or a steel, for example, a heat-resistant steel with a material number 1.4767, or a composite material. The base body preferably comprises a plate or honeycomb structure configured to provide a large reactive surface.The base body, which is in particular plate- or honeycomb-shaped, preferably forms a plurality of exhaust gas flow channels. The exhaust gas flow purification device is preferably configured to direct the exhaust gas flow from an upstream process stage, such as an SOFC fuel cell, in particular in a fluid-tight manner, to a downstream process stage, such as a heat exchanger and / or an environment. It is conceivable for the exhaust gas flow purification device to have at least one inlet opening, arranged at least upstream of the catalyst element, which is configured to supply ambient air, preferably containing oxygen, to the exhaust gas flow. The catalyst element is preferably configured as a carbon monoxide oxidation catalyst element. "Configured" is to be understood in particular as specifically designed and / or equipped.The fact that an object is designed for a specific function should be understood in particular to mean that the object fulfills and / or performs this specific function in at least one application and / or operating state. A “honeycomb structure” should be understood in particular to mean a plurality of flow channels arranged next to one another, which are delimited in particular by at least one, preferably at least two side surfaces, which each delimit two flow channels arranged next to one another, in particular at least partially, preferably at least substantially. A “main direction of extension” of an object should be understood in particular to mean a direction which runs parallel to a longest edge of a smallest geometric cuboid which just completely encloses the object.A "chromium component" is understood to mean, in particular, a chemical compound containing at least one chromium atom, in particular a chromium compound, which is present in the exhaust stream. The chromium components could, for example, be formed as a Cr(VI)-containing component, such as dihydrogen chromate, Cr(VI) oxyhydroxide, chromium(VI) oxide, and / or as a Cr(III), Cr(IV), and / or Cr(VI)-containing reaction and / or condensation product.

[0006] Preferably, the catalyst element, in particular the reactive catalyst material of the catalyst element, is arranged at least substantially in the exhaust gas stream. In particular, the reactive catalyst material is formed at least as a non-ferrous material and / or iron material and / or precious metal, for example platinum, palladium, and / or rhodium. Preferably, the reactive catalyst material is configured to at least oxidize at least one exhaust gas constituent, in particular at least carbon monoxide. The oxidized carbon monoxide is preferably formed as carbon dioxide.An "exhaust gas constituent" is understood to mean, in particular, at least one, preferably gaseous, chemical component of the exhaust gas stream, such as carbon monoxide, hydrogen, ammonia, hydrogen sulfide, carbon, formaldehyde, formic acid, thiophene, hydrogen cyanide, and / or comparable chemical components that are at least substantially oxidizable at an operating temperature of the catalyst element. "At least substantially" in this context is understood to mean, in particular, that a deviation from a predetermined value deviates by less than 25%, preferably less than 10%, and particularly preferably less than 5% of the predetermined value.

[0007] The chromium protective material preferably chemically and / or physically binds, in particular at least a large portion, preferably at least substantially, of the chromium constituents contained in the exhaust gas stream. For example, the chromium protective material could be configured to chemically react with gaseous chromium constituents from the exhaust gas stream, in particular to chemically bind the chromium constituents. For example, the chromium protective material could be configured to bind liquid chromium constituents from the exhaust gas stream, in particular adhesively and / or cohesively. For example, the chromium protective material could be configured to mechanically fix solid chromium particles in the chromium protective material. In particular, the chromium protective element is configured to at least substantially remove the chromium constituents from the exhaust gas stream by binding to the chromium protective material.Alternatively or additionally, the chromium protective material is designed to chemically and / or physically bind sulfur components. The chromium protective material is preferably in the form of a micro- and / or mesoporous material, such as zeolites. Alternatively or additionally, the chromium protective material is in the form of an alkaline earth metal, for example an oxide of the alkaline earth metal, and / or iron and non-ferrous metal compounds, and / or an alkali metal, for example sodium, and / or in an H-form of zeolites. It is conceivable for the chromium protective material to be in the form of a mixture and / or mixed oxides of various chromium protective materials. The chromium protective material is preferably designed to bind chromium components in the exhaust gas stream at an operating temperature of less than 300°C, preferably less than 280°C, and preferably between 200°C and 230°C, or in particular at least 150°C.In particular, the operating temperature is present for more than 80% of the operating time. However, it is conceivable that the operating temperature may temporarily reach up to 450°C, particularly during start-up / abrupt load changes or the like of the upstream SOFC fuel cell or comparable machine. In particular, the bound chromium components remain bound at least substantially over the service life of the chromium protection element. For example, the chromium protection element is designed for an amount of chromium that is expected to be bound over the service life of the chromium protection element. It is conceivable that the chromium protection element is designed to be retrofittable and / or replaceable. The expression “at least a large part” is to be understood in particular as at least 55%, advantageously at least 65%, preferably at least 75%, particularly preferably at least 85% and particularly advantageously at least 95%.

[0008] It is further proposed that the chromium protective material of the chromium protective element be arranged so as to be distributed at least substantially uniformly over a functional surface of the catalyst element. Advantageously, low manufacturing and / or assembly complexity can be provided, since, in particular, the chromium protective element is not directional. Advantageous properties with regard to design can be provided, since, in particular, the uniform distribution allows for a small installation space to be provided. Preferably, the ratio between chromium protective material and catalyst material, in particular at least on the functional surface, is at least substantially constant. A “functional surface” is to be understood in particular as a surface which is in contact with the exhaust gas flow and / or which is designed to treat the exhaust gas flow.

[0009] Furthermore, it is proposed that the chromium protection element be arranged at least substantially upstream of the catalyst element along an exhaust gas flow direction. Advantageously, a particularly long service life can be provided since, in particular, the chromium components of the exhaust gas flow are bound first and the catalyst material downstream in the flow direction is not impaired. The exhaust gas flow purification device preferably has at least one exhaust gas flow inlet and at least one exhaust gas flow outlet. The exhaust gas flow inlet is preferably configured to supply the catalyst element and / or the chromium protection element with an exhaust gas flow to be treated. The exhaust gas flow outlet is preferably configured to discharge the exhaust gas flow treated by the catalyst element and / or the chromium protection element.Preferably, at least the catalyst element and / or the chromium protection element, preferably the functional surface, is arranged along the exhaust gas flow direction between the at least one exhaust gas flow inlet and the at least one exhaust gas flow outlet. Preferably, the exhaust gas flow direction is directed from the at least one exhaust gas flow inlet to the at least one exhaust gas flow outlet. Preferably, the exhaust gas flow direction is arranged at least substantially parallel to at least one of the exhaust gas flow channels of the catalyst element. The phrase "in front of the catalyst element" is to be understood in particular as a position on a side of the catalyst element facing the exhaust gas flow inlet. In particular, the position is arranged in a vicinity of the exhaust gas flow inlet, preferably within an exhaust gas flow supply element fluidly connected to the inlet.The chrome protection element is preferably designed as a separate component that is arranged and / or attached to the catalyst element. It is conceivable for the chrome protection element to be formed integrally with the catalyst element. It is conceivable for the chrome protection element to be arranged at least in a front third of the catalyst element. In particular, the vicinity of the exhaust gas flow inlet or the exhaust gas flow outlet is formed by all points that are at a distance from the exhaust gas flow inlet or the exhaust gas flow outlet that is less than 30 cm, preferably 15 cm, advantageously 10 cm, and preferably 5 cm.

[0010] Furthermore, it is proposed that a chromium protective material concentration is distributed unevenly, for example asymmetrically, preferably along an exhaust gas flow direction. Advantageously, a design can be provided with low costs since, in particular, the uneven chromium protective material concentration means that less chromium protective material needs to be used and / or can be used more efficiently. Preferably, the catalyst element has a particularly high concentration in the vicinity of the exhaust gas flow inlet. Preferably, the catalyst element has a particularly low chromium protective material concentration in a vicinity of the exhaust gas flow outlet. It is conceivable that the chromium protective material concentration is distributed unevenly in a circumferential direction of the catalyst element. It is conceivable that the chromium protective material is arranged, for example in sections, on the functional surface of the catalyst element.A “chromium protective material concentration” should be understood in particular as a quantity of chromium protective material per unit area.

[0011] It is further proposed that a chromium protective material concentration, preferably a ratio of the chromium protective material concentration to a catalyst material concentration, decreases in the flow direction. Advantageously, a particularly long service life can be provided since, in particular, the chromium constituents of the exhaust gas flow are bound first and the catalyst material following in the flow direction is no longer impaired. Preferably, the ratio of the chromium protective material concentration to a catalyst material concentration decreases at least substantially uniformly in the flow direction, in particular between the exhaust gas flow inlet and the exhaust gas flow outlet. Alternatively, it is conceivable that the ratio of the chromium protective material concentration to the catalyst material concentration decreases exponentially in the flow direction, in particular between the exhaust gas flow inlet and the exhaust gas flow outlet.Alternatively, it is conceivable that the ratio of the chromium protective material concentration to the catalyst material concentration decreases in a stepwise manner in the flow direction, in particular between the exhaust gas flow inlet and the exhaust gas flow outlet, with the ratio of the chromium protective material concentration to the catalyst material concentration in the flow direction remaining constant in some sections and abruptly changing in other sections. A "catalyst material concentration" is to be understood in particular as an amount of catalyst material per unit area.

[0012] In addition, it is proposed that the chromium protection element be designed as an at least single-layer, preferably multi-layer diffusion protection layer, which is at least designed to prevent chromium from being released from the catalyst element into the exhaust gas stream, in particular by diffusion. Advantageously, a high exhaust gas purification performance can be provided, since, in particular, chromium loading of the catalyst element can be kept particularly low. In particular, the diffusion protection layer is at least substantially permeable to the exhaust gas components, preferably at least permeable to carbon monoxide. It is conceivable that the diffusion protection layer is also permeable to chromium components, wherein the diffusion protection layer binds the chromium components, in particular upon diffusion through. The individual diffusion layers are preferably arranged directly on top of one another, in particular in contact with one another.Alternatively, the diffusion layers could be arranged alternately with catalyst layers of the catalyst element. For example, the diffusion layer is arranged above and / or below the catalyst layers.

[0013] Additionally, an SOFC fuel cell with at least one exhaust stream purification device is proposed. Advantageously, a long service life can be provided, since, in particular, the chromium protective element binds the chromium components from the exhaust stream, thereby preventing a reduction in catalytic performance, such as clogging of the catalyst element. Advantageously, high operational safety / reliability can be provided, since, in particular, the chromium protective element can prevent a reduction in catalytic performance, such as clogging of the catalyst element, thereby ensuring a high exhaust stream purification performance of the catalyst element. Advantageously, a low-cost design can be provided, since, in particular, the chromium protective element requires less catalyst material.Advantageously, a high level of environmental protection can be achieved, since, in particular, the chromium protective element binds the chromium components in the exhaust stream, preventing them from being emitted into the environment. It is conceivable that the SOFC fuel cell, in particular several fuel cells forming a fuel cell stack, generates multiple exhaust streams and therefore has multiple exhaust stream purification devices.

[0014] Furthermore, a method for cleaning the exhaust gas stream which is passed through the exhaust gas stream cleaning device is proposed, wherein carbon monoxide contained in the exhaust gas stream is oxidized, and wherein chromium, preferably chromium(VI) oxide, contained in the exhaust gas stream is bound. A long service life can be provided advantageously, since in particular the chromium protective element binds the chromium components from the exhaust gas stream and thereby prevents a reduction in catalytic performance, such as clogging of the catalyst element. A high level of operational safety / reliability can be provided advantageously, since in particular the chromium protective element can prevent a reduction in catalytic performance, such as clogging of the catalyst element, and thereby ensure a high exhaust gas stream cleaning performance of the catalyst element.Advantageously, a low-cost design can be provided, particularly because the chromium protection element requires less catalyst material. Advantageously, high environmental protection can be provided, particularly because the chromium protection element binds the chromium components in the exhaust stream, preventing them from being emitted into the environment. It is conceivable that the chromium protection element binds a compound in gaseous form, such as chromic acid CrO2(OH)2, liquid form, and / or solid form.

[0015] The exhaust gas purification device according to the invention, the SOFC fuel cell according to the invention, and the method according to the invention are not intended to be limited to the application and embodiment described above. In particular, the exhaust gas purification device according to the invention, the SOFC fuel cell according to the invention, and the method according to the invention may, in order to fulfill a function described herein, have a number of individual elements, components, units, and method steps that differs from the number stated herein. Furthermore, in the value ranges specified in this disclosure, values ​​within the stated limits are also intended to be considered disclosed and can be used arbitrarily. drawing

[0016] Further advantages will become apparent from the following description of the drawings. The drawings illustrate four exemplary embodiments of the invention. The drawings, the description, and the claims contain numerous features in combination. Those skilled in the art will also expediently consider the features individually and combine them into useful further combinations.

[0017] They show: Fig. 1 a SOFC fuel cell with an exhaust gas purification device, Fig. 2 a schematic representation of a process for cleaning an exhaust gas stream, Fig. 3 an alternative exhaust gas purification device with an alternative chrome protection element, Fig. 4 a further alternative exhaust gas purification device with a further alternative chromium protection element and Fig. 5 a further alternative exhaust gas purification device with a further alternative chromium protection element. Description of the embodiments

[0018] The Fig. 1 shows a schematic SOFC fuel cell 22a. The SOFC fuel cell 22a generates an exhaust gas stream 10a. The SOFC fuel cell 22a could also generate multiple exhaust gas streams 10a. Alternatively, the SOFC fuel cell 22a could also be configured as a combustion engine and / or a comparable upstream process that generates an exhaust gas stream 10a. The SOFC fuel cell 22a is fluidly connected to an exhaust gas purification device. The exhaust gas purification device has an exhaust gas inlet 28a. The exhaust gas purification device has an exhaust gas outlet 30a. The exhaust gas purification device has a base body 20a. The base body 20a forms the exhaust gas inlet 28a and the exhaust gas outlet 30a. The base body 20a is made of steel. Alternatively, the base body 20a could also be made of a ceramic. The base body 20 comprises the catalyst material and the chromium protection material.The base body 20 has a honeycomb structure 24a. The honeycomb structure 24a is configured to provide a large reactive functional surface 16a. Furthermore, the honeycomb structure 24 is configured to ensure high stability of the exhaust gas purification device. Alternatively, the base body 20a could also have a plate structure. The base body 20a forms a plurality of exhaust gas flow channels 26a. The exhaust gas purification device is configured to conduct the exhaust gas flow 10a. The base body 20a is configured to conduct a partial flow of the exhaust gas flow 10a in each of the exhaust gas flow channels 26a. Alternatively, it is conceivable for only a portion of the exhaust gas flow channels 26a to conduct the partial flow of the exhaust gas flow 10a. The exhaust gas flow 10a has an exhaust gas flow direction 18a. The exhaust gas flow direction 18a is arranged parallel to a main extension direction of the exhaust gas flow channels 26a.It is conceivable that a part of the exhaust gas flow 10a diffuses perpendicular to the exhaust gas flow direction 18a into and / or through the base body 20a.

[0019] The exhaust gas purification device comprises a catalyst element 12a. The catalyst element 12a is arranged in the exhaust gas stream 10a. The catalyst element 12a is arranged between the exhaust gas stream inlet 28a and the exhaust gas stream outlet 30a. The catalyst element 12a comprises a catalyst material. The catalyst material is formed as a noble metal, non-ferrous metal, or iron metal. The catalyst material could, for example, be formed as a platinum metal, rhodium, palladium, and / or other reactive materials. The catalyst element 12a is configured to oxidize the exhaust gas constituents contained in the exhaust gas stream 10a. One of the exhaust gas constituents is formed as carbon monoxide. Alternatively or additionally, the exhaust gas stream 10a comprises chromium-containing chemical compounds. Alternatively or additionally, the exhaust gas stream 10a could also comprise sulfur constituents or a comparable exhaust gas constituent.The exhaust gas purification device comprises a chromium protection element 14a. The chromium protection element 14a is arranged in the exhaust gas stream 10a. The chromium protection element 14a is arranged between the exhaust gas stream inlet 28a and the exhaust gas stream outlet 30a. The chromium protection element 14a comprises a chromium protection material. The chromium protection material is formed as a micro- and / or mesoporous material, such as zeolite. The chromium protection material is formed as an alkaline earth metal, alkali metal, for example sodium, and / or in an H-form of zeolite. The chromium protection element 14a is configured to bind chromium components from the exhaust gas stream 10a. Alternatively or additionally, the chromium protection element 14a is configured to bind sulfur components from the exhaust gas stream 10a. The chromium protection material is configured to bind chromium components in the exhaust gas stream 10a at an operating temperature of approximately 200°C to 250°C.The chromium components in the exhaust gas stream 10a are in the form of chromium(VI) oxide, Cr(VI)-containing components such as dihydrogen chromate, Cr(VI) oxyhydroxide, chromium(VI) oxide, and / or a Cr(III)-containing, Cr(IV)-containing, and / or Cr(VI)-containing reaction and / or condensation product. Alternatively or additionally, the chromium could also be in the form of chromic acid CrO2(OH)2. It is conceivable that the chromium components are present in a different chemical structure. The chromium protective material of the chromium protective element 14a is distributed uniformly / homogeneously over the functional surface 16a of the catalyst element 12a. The chromium protective material and the catalyst material have the same ratio across the entire functional surface 16a.

[0020] The Fig. 2 shows a schematic flow diagram of a method for cleaning the exhaust gas stream 10a.

[0021] In a method step 32a, the exhaust gas stream 10a is passed through the exhaust gas purification device. The exhaust gas stream 10a is passed in a fluid-tight manner from the exhaust gas inlet 28a to the exhaust gas outlet 30a. The exhaust gas stream 10a is passed through the exhaust gas flow channels 26a. The exhaust gas stream 10a is passed past the chromium protection element 14a and the catalyst element 12a.

[0022] In a further process step 34a, carbon monoxide contained in the exhaust gas stream 10a is oxidized. For this purpose, oxygen-containing ambient air is supplied to the exhaust gas stream 10a. Exhaust gas components of the exhaust gas stream 10a are oxidized at a reaction temperature of approximately 200 °C to 240 °C. It is conceivable that the reaction temperature may be briefly increased to temperatures up to 450 °C.

[0023] In a further process step 36a, chromium components contained in the exhaust gas stream 10a, preferably chromium(VI) oxide, are bound. The chromium components contained in the exhaust gas stream 10a are bound over the entire service life of the chromium protection element 14a. The required amount of chromium protection material is determined based on the amount of chromium expected over the service life of the chromium protection element 14a.

[0024] In the Fig. 3 to 5 show further embodiments of the invention. The following descriptions and the drawings are essentially limited to the differences between the embodiments, whereby with regard to components with the same designation, in particular with regard to components with the same reference numerals, reference is also made to the drawings and / or the description of the other embodiments, in particular to the Fig. 1 and Fig. 2. To distinguish the embodiments, the letter a is added to the reference numerals of the embodiment in the Fig. 1 and Fig. 2. In the examples of the Fig. 3 to 5, the letter a is replaced by the letters b to d.

[0025] The Fig. 3 shows a schematic representation of an alternative exhaust gas purification device. The alternative exhaust gas purification device is configured to conduct an exhaust gas flow 10b. The exhaust gas flow 10b has an exhaust gas flow direction 18b. The alternative exhaust gas purification device has a base body 20b. The alternative exhaust gas purification device has a chromium protection base body 38b. The alternative exhaust gas purification device has a catalyst element 12b. The catalyst element 12b has a catalyst material. The catalyst material is arranged on the base body 20b. The catalyst material is arranged in the exhaust gas flow 10b. The catalyst element 12b is configured to oxidize exhaust gas components of the exhaust gas flow 10b. The alternative exhaust gas purification device has an alternative chromium protection element 14b. The alternative chromium protection element 14b is configured to bind chromium components from the exhaust gas flow 10b.The alternative chrome protection element 14b is arranged upstream of the catalyst element 12b along an exhaust gas flow direction 18b of the exhaust gas stream 10b. The base body 20b is fixed to the chrome protection base body 38b. Alternatively, the chrome protection base body 38b and the base body 20b could be formed integrally. The chrome protection element 14b is designed to be replaceable.

[0026] The Fig. 4 shows a schematic representation of an alternative exhaust gas purification device. The alternative exhaust gas purification device is configured to conduct an exhaust gas flow 10c. The exhaust gas flow 10c has an exhaust gas flow direction 18c. The alternative exhaust gas purification device has a base body 20c. The alternative exhaust gas purification device has a catalyst element 12c. The catalyst element 12c has a catalyst material. The catalyst material is arranged on the base body 20c. The catalyst material is arranged in the exhaust gas flow 10c. The catalyst element 12c is configured to oxidize exhaust gas components of the exhaust gas flow 10c. The alternative exhaust gas purification device has an alternative chromium protection element 14c. The alternative chromium protection element 14c is configured to bind chromium components from the exhaust gas flow 10c. The chromium protection element 14c has a chromium protection material concentration.The chromium protective material concentration is unevenly distributed along an exhaust gas flow direction 18c. The uneven distribution is asymmetrically distributed along the exhaust gas flow direction 18c. A ratio of the chromium protective material concentration to a catalyst material concentration decreases in the exhaust gas flow direction 18c. The ratio of the chromium protective material concentration to the catalyst material concentration decreases linearly in the flow direction 18c. Alternatively, the decrease in the ratio of the chromium protective material concentration to the catalyst material concentration could be nonlinear in the flow direction 18c, for example, decreasing exponentially or stepwise. It is conceivable that the ratio of the chromium protective material concentration to the catalyst material concentration decreases arbitrarily in the flow direction 18c.

[0027] The Fig.5 shows a schematic representation of an alternative exhaust gas purification device. The alternative exhaust gas purification device is configured to conduct an exhaust gas flow 10d. The exhaust gas flow 10d has an exhaust gas flow direction 18d. The alternative exhaust gas purification device has a base body 20d. The alternative exhaust gas purification device has a catalyst element 12d. The catalyst element 12d has a catalyst material. The catalyst material is arranged on the base body 20d and in the exhaust gas flow 10d. The catalyst element 12d is configured to oxidize exhaust gas components of the exhaust gas flow 10d. The alternative exhaust gas purification device has an alternative chromium protection element 14d. The alternative chromium protection element 14d is configured to bind chromium components from the exhaust gas flow 10d. The chromium protection element 14d is designed as a single-layer diffusion protection layer 40d.The diffusion protection layer 40d is designed to prevent chromium from being released from the catalyst element 12d to the exhaust gas stream 10d by diffusion. The diffusion protection layers 40d and the catalyst layers of the catalyst element 12d are arranged alternately perpendicular to the exhaust gas flow direction 18d. Alternatively, several diffusion protection layers 40d could be arranged in mutual contact to form a multilayer diffusion protection layer 40d. It is conceivable for the chromium protection element 14d to be designed as a multilayer diffusion protection layer 40d.

Claims

[1] Exhaust gas flow purification device which is at least designed to conduct an exhaust gas flow (10a; 10b; 10c; 10d), with at least one catalyst element (12a; 12b; 12c; 12d) arranged in the exhaust gas flow (10a; 10b; 10c; 10d), which has at least one catalyst material, and which is designed to at least substantially oxidise at least one exhaust gas component of the exhaust gas components contained in the exhaust gas flow (10a; 10b; 10c; 10d), characterized by at least one chromium protection element (14a; 14b; 14c; 14d) which is arranged in the exhaust gas stream (10a; 10b; 10c; 10d), which has at least one chromium protection material, and which is designed to bind chromium components, preferably chromium(VI) oxide, from the exhaust gas stream (10a; 10b; 10c; 10d). [2] Exhaust gas purification device according to claim 1, characterized bythat the chromium protective material of the chromium protective element (14a; 14b; 14c) is arranged distributed at least substantially uniformly over a functional surface (16a; 16b; 16c) of the catalyst element (12a; 12b; 12c). [3] Exhaust gas purification device according to one of claims 1 or 2, characterized by that the chromium protection element (14b) is arranged at least substantially in front of the catalyst element (12b) along an exhaust gas flow direction (18b). [4] Exhaust gas purification device according to one of claims 1 or 2, characterized by that a chromium protective material concentration is distributed unevenly, for example asymmetrically, preferably along an exhaust gas flow direction (18c). [5] Exhaust gas purification device according to claim 4, characterized by that a chromium protective material concentration, preferably a ratio of the chromium protective material concentration to a catalyst material concentration, decreases in the exhaust gas flow direction (18c). [6] Exhaust gas flow purification device according to one of the preceding claims, characterized by that the chromium protection element (14d) is designed as an at least single-layer, preferably multi-layer diffusion protection layer (40d) which is at least designed to prevent chromium release from the catalyst element (12d) to the exhaust gas stream (10d), in particular by diffusion. [7] SOFC fuel cell (22a; 22b; 22c; 22d) with at least one exhaust gas flow purification device according to one of the preceding claims. [8] Method for purifying the exhaust gas stream (10a; 10b; 10c; 10d) which is passed through the exhaust gas purification device, wherein at least one carbon monoxide contained in the exhaust gas stream (10a; 10b; 10c; 10d) is oxidized, characterized by that a chromium, preferably chromium(VI) oxide, contained in the exhaust gas stream (10a; 10b; 10c; 10d) is bound.

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