DE102023114997A1 - Device and method for characterizing a catalyst at different aging times - Google Patents

Abstract

The present invention relates to a device (10) for characterizing a catalytic converter (12) at different aging times, comprising a catalytic converter (12) to be characterized, a burner (14) for generating exhaust gas, the burner (14) having a fuel supply unit (16). for supplying fuel (B) into the burner (14), and an air supply device (18) for supplying air (L) into the burner (14), a supply line (20) for supplying the exhaust gas generated in the burner (14). to the catalyst (12), an addition unit (24) arranged in the feed line (20) for adding synthesis gas (S) to the exhaust gas generated by the burner (14), a first measuring device arranged in the feed line (20) downstream of the addition unit (24). (34) for determining the composition of the exhaust gas supplied to the catalyst (12), a discharge line (22) for discharging the exhaust gas treated in the catalyst (12), and a second measuring device (54) arranged in the discharge line (22) for determining the composition of the exhaust gas treated by the catalytic converter (12). In addition, the invention relates to a corresponding method and a computer program product for carrying out this method.

Description

The present invention relates to a device for characterizing a catalyst at different aging times. In addition, the invention relates to a corresponding method.

STATE OF THE ART

Catalysts are used to chemically convert the pollutants contained in the exhaust gases of internal combustion engines into non-toxic substances. The main pollutants contained in the exhaust gas are hydrocarbons (CmHn), carbon monoxide (CO) and nitrogen oxides (NOx), which are ideally completely converted into carbon dioxide (CO2), water (H2O) and nitrogen (N2) by means of oxidation or reduction using a catalyst .

Catalysts are subject to an aging process, which manifests itself in a decreasing emission conversion rate of the pollutants mentioned above. While a new catalytic converter has emission conversion rates of 99% or more, the emission conversion rates decrease as the catalytic converter is in operation until they fall below a legally specified value, as a result of which the catalytic converter in question must be replaced. The aging process differs significantly from catalyst to catalyst, especially because the so-called “washcoat” has a very different structure. A washcoat is understood to mean porous layers of the catalyst on which catalytically active substances, in particular precious metals such as palladium, platinum and/or rhodium, as well as oxygen storage units such as cerium dioxide (CeO ₂ ) are applied. Due to the high temperatures that affect the washcoat during operation, crystallization processes occur, which reduce the active surface of the washcoat. A reduction in active surface area is one of the causes of decreasing emission conversion rates.

In order to be able to estimate when the catalyst in question needs to be replaced, the catalyst must be characterized at different aging times. For this purpose, the usable oxygen capacity, also known as “Oxygen Storage Capacity” (OSC), is usually used. For characterization, the catalyst is aged in a suitably constructed test stand and then characterized in another test stand or in the laboratory at different aging times. There is a test stand on which the catalyst can be aged EP 1 521 903 A1 disclosed. This results in the need to transport the catalyst to be characterized back and forth either between two test stands or between the test stand and the laboratory, which represents a considerable logistical and time-consuming effort.

DISCLOSURE OF INVENTION

• - einen zu charakterisierenden Katalysator,
• - einen Brenner zum Erzeugen von Abgas, wobei der Brenner
  • ◯ eine Brennstoffzufuhreinheit zum Zuführen von Brennstoff in den Brenner, und
  • ◯ eine Luftzufuhreinrichtung zum Zuführen von Luft in den Brenner umfasst,
• - eine Zuführleitung zum Zuführen des im Brenner erzeugten Abgases zum Katalysator,
• - eine in der Zuführleitung angeordnete Zugabeeinheit zum Zugeben von Synthesegas zum vom Brenner erzeugten Abgas,
• - eine in der Zuführleitung stromabwärts der Zugabeeinheit angeordnete erste Messeinrichtung zum Bestimmen der Zusammensetzung des dem Katalysator zugeführten Abgases,
• - eine Abführleitung zum Abführen des im Katalysator behandelten Abgases, und
• - eine in der Abführleitung angeordnete zweite Messeinrichtung zum Bestimmen der Zusammensetzung des vom Katalysator behandelten Abgases.

One embodiment of the invention relates to a device for characterizing a catalyst at different aging times, comprising

• - a catalyst to be characterized,
• - a burner for producing exhaust gas, the burner
  • ◯ a fuel supply unit for supplying fuel to the burner, and
  • ◯ comprises an air supply device for supplying air into the burner,
• - a supply line for supplying the exhaust gas generated in the burner to the catalytic converter,
• - an addition unit arranged in the supply line for adding synthesis gas to the exhaust gas generated by the burner,
• - a first measuring device arranged in the supply line downstream of the addition unit for determining the composition of the exhaust gas supplied to the catalyst,
• - a discharge line for discharging the exhaust gas treated in the catalyst, and
• - A second measuring device arranged in the discharge line for determining the composition of the exhaust gas treated by the catalyst.

It is not necessary to characterize the catalytic converter in a test vehicle. However, in order to produce an exhaust gas composition with the burner which is comparable to that produced by an internal combustion engine, the proposed device has an addition unit with which synthesis gas can be added to the exhaust gas generated by the burner. Due to the addition of the synthesis gas, the present device can produce an exhaust gas composition which is comparable to that produced by an internal combustion engine.

The device can be operated in two modes. In order to age the catalyst in question, it is not necessary to add synthesis gas. As a result, in a first mode (“aging mode”), an exhaust gas is supplied to the catalytic converter, which is stored in the burner using fuel (petrol or diesel fuel) and Air has been generated. This is advantageous in that the synthesis gas is comparatively expensive. No measurement is performed during aging mode. Once the relevant aging point has been reached, the device is operated in a second mode (“characterization mode”) in which the synthesis gas is added to the exhaust gas generated by the burner. A measurement of the composition of the exhaust gas is now also carried out in the first measuring device and in the second measuring device. The first measuring device is arranged upstream of the catalytic converter and the second measuring device is arranged downstream of the catalytic converter. The structure of the two measuring devices can be largely identical. In the two measuring devices, the exhaust gas is examined for the relevant pollutants, in particular hydrocarbons (CmHn), carbon monoxide (CO) and nitrogen oxides (NOx). By comparing the measurements upstream and downstream of the catalyst, the respective emission conversion rates can be determined and the catalyst can be characterized accordingly.

After the characterization has been completed, the device is operated again in aging mode until the next aging point is reached. The device is then switched back to characterization mode and the catalyst is characterized. The two modes are repeated until the characterization of the catalyst is completed at all desired aging times.

• - in der Zuführleitung stromabwärts der Zugabeeinheit eine erste Sauerstoffsonde zum Bestimmen des Verbrennungsluftverhältnisses des dem Katalysator zugeführten Abgases, und/oder
• - in der Abführleitung eine zweite Sauerstoffsonde zum Bestimmen des Verbrennungsluftverhältnisses des vom Katalysator behandelten Abgases angeordnet sein.

According to another embodiment, you can

• - in the supply line downstream of the addition unit, a first oxygen probe for determining the combustion air ratio of the exhaust gas supplied to the catalytic converter, and/or
• - A second oxygen probe for determining the combustion air ratio of the exhaust gas treated by the catalyst can be arranged in the discharge line.

The combustion air ratio is also known as the air ratio or air ratio and is abbreviated with the letter λ. The combustion air ratio indicates the mass ratio of air to fuel relative to the stoichiometrically ideal ratio for a theoretically complete combustion process. As mentioned at the beginning, the characterization of a catalyst is mainly carried out using OSC. To determine the OSC, however, it is essential to know the combustion air ratio of the exhaust gas supplied to the catalytic converter and the combustion air ratio of the exhaust gas treated by the catalytic converter.

It is advisable to use so-called broadband oxygen probes instead of jump probes as oxygen probes. Jump sensors only indicate whether a rich or lean mixture is present, while broadband oxygen sensors are able to precisely quantify the combustion air ratio. Consequently, it is also possible to determine not only the OSC, but also the maximum oxygen capacity, also known as the “Maximum Oxygen Load” (MOL).

As mentioned at the beginning, the characterization of prior art catalysts is often carried out using test vehicles, which usually have a jump probe downstream of the catalyst. As a result, exact quantification of the combustion air ratio and MOL is not possible.

The characterization of the catalyst can be carried out using the proposed device in terms of the OSC and the MOL and is therefore more informative.

• - in der Zuführleitung stromabwärts der Zugabeeinheit ein erster Temperatursensor zum Bestimmen der Temperatur des dem Katalysator zugeführten Abgases, und/oder
• - in der Abführleitung ein zweiter Temperatursensor zum Bestimmen der Temperatur des vom Katalysator behandelten Abgases angeordnet sein.

In a further developed embodiment can

• - in the supply line downstream of the addition unit, a first temperature sensor for determining the temperature of the exhaust gas supplied to the catalytic converter, and/or
• - A second temperature sensor for determining the temperature of the exhaust gas treated by the catalytic converter can be arranged in the discharge line.

As mentioned at the beginning, the temperature and in particular the temperature load on the washcoat plays a major role in the aging process of a catalytic converter. In this embodiment it is therefore possible to determine aging as a function of temperature. This allows conclusions to be drawn about temperatures or temperature ranges that accelerate aging of the catalytic converter and should therefore be avoided when operating a vehicle or only act on the catalytic converter for a short time.

In a further developed embodiment, at least one catalyst temperature sensor can be arranged in the catalytic converter for determining the temperature of the exhaust gas flowing through the catalytic converter. As mentioned, depending on the embodiment, a temperature sensor can be arranged upstream and downstream of the catalytic converter. Particularly for the simulation of the aging process, it is also of interest how the Temperature inside the catalyst behaves. A statement in this regard can be obtained using a catalytic converter temperature sensor, which determines the temperature of the exhaust gas within the catalytic converter.

In a further embodiment, a first branch can be arranged downstream in the feed line, from which a bypass line branches off from the feed line, wherein a first control element for adjusting the volume flow flowing through the bypass line can be arranged in the first branch or in the bypass line. The first actuating element can be designed, for example, as a flap or a throttle valve. The volume flow that flows through the catalytic converter can also be adjusted using the volume flow that flows through the bypass line. This makes it possible to determine the aging process and the characterization depending on the volume flow. It should be pointed out at this point that it is usually relatively easy to draw conclusions about the mass flow from the volume flow, provided that this is relevant.

A further developed embodiment can be characterized in that a second branch is arranged in the discharge line, from which a return line branches off, with which the exhaust gas treated by the catalyst can be returned to the burner or into the supply line, in the second branch or in the bypass line a second adjusting element is arranged for adjusting the volume flow flowing through the return line. In this case too, the second control element can be a flap or a throttle valve in order to adjust the volume flow of the recirculated exhaust gas. The volume flow of the recirculated exhaust gas can be used to adjust the temperature of the exhaust gas that is applied to the catalytic converter. In the event that the device has the aforementioned first actuator and the second actuator, it is possible to set the temperature independently of the volume flow. This allows the catalyst to be characterized in its entire operating range.

According to a further embodiment, a third temperature sensor for determining the temperature of the recirculated exhaust gas can be arranged in the return line. Using the third temperature sensor, cooling processes of the exhaust gas that is passed through the return line can be taken into account more precisely when setting the temperature of the exhaust gas that is fed to the catalytic converter. Overall, the characterization of the catalyst in question is made more precise using the third temperature sensor.

• - Charakterisieren eines Katalysators, wozu folgende Charakterisierungsschritte durchgeführt werden:
  • ◯ Erzeugen von Abgas mittels des Brenners, wobei dem Brenner Brennstoff mit der Brennstoffzufuhreinheit und Luft mit der Luftzufuhreinrichtung zugeführt werden,
  • ◯ Zuführen des im Brenner erzeugten Abgases zum Katalysator durch die Zuführleitung,
  • ◯ Zugeben von Synthesegas zum vom Brenner erzeugten Abgases mit der Zugabeeinheit in die Zuführleitung, und
  • ◯ Bestimmen der Zusammensetzung des dem Katalysator zugeführten Abgases mittels der ersten Messeinrichtung und/oder des vom Katalysator behandelten Abgases mit der zweiten Messeinrichtung, oder
• - Altern des Katalysators, wozu folgende Alterungsschritte durchgeführt werden:
  • ◯ Erzeugen von Abgas mittels des Brenners, wobei dem Brenner Brennstoff mit der Brennstoffzufuhreinheit und Luft mit der Luftzufuhreinrichtung zugeführt werden, und
  • ◯ Zuführen des im Brenner erzeugten Abgases zum Katalysator durch die Zuführleitung.

One embodiment of the invention relates to a method for operating a device according to one of the previous embodiments for characterizing a catalyst at different aging times, comprising the following steps:

• - Characterizing a catalyst, for which the following characterization steps are carried out:
  • ◯ generating exhaust gas by means of the burner, fuel being supplied to the burner with the fuel supply unit and air with the air supply device,
  • ◯ Supplying the exhaust gas generated in the burner to the catalytic converter through the supply line,
  • ◯ Adding synthesis gas to the exhaust gas generated by the burner with the addition unit into the supply line, and
  • ◯ Determining the composition of the exhaust gas supplied to the catalytic converter using the first measuring device and/or the exhaust gas treated by the catalytic converter using the second measuring device, or
• - Aging of the catalyst, for which the following aging steps are carried out:
  • ◯ Generating exhaust gas by means of the burner, with fuel being supplied to the burner with the fuel supply unit and air with the air supply device, and
  • ◯ Supplying the exhaust gas generated in the burner to the catalytic converter through the supply line.

The technical effects and advantages that can be achieved with the proposed method correspond to those that have been discussed for the present device. In summary, it should be noted that extensive characterization of a given catalyst is possible with a single device without the need to transport the catalyst back and forth between two test benches. This significantly simplifies and accelerates the characterization of the given catalyst.

A further embodiment of the invention relates to a computer program product with a program code, which is stored on a medium readable by a computer, for carrying out the method according to the previously described training. Regarding the technical effects and advantages that can be achieved with the computer program product, please refer to the relevant explanations of the process.

EMBODIMENT OF THE INVENTION

• 1 eine prinzipielle Darstellung einer Ausführungsform einer erfindungsgemäßen Vorrichtung zum Charakterisieren eines Katalysators zu verschiedenen Alterungszeitpunkten.

Exemplary embodiments of the invention are explained in more detail below with reference to the accompanying drawing. It shows

• 1 a basic representation of an embodiment of a device according to the invention for characterizing a catalyst at different aging times.

In 1 an exemplary embodiment of a device 10 according to the invention for characterizing a catalyst 12 at different aging times is shown using a basic representation. The device 10 includes a catalyst 12 that is to be characterized. In addition, the device 10 has a burner 14 with which an exhaust gas can be generated. To generate the exhaust gas, a fuel B, for example gasoline or diesel fuel, can be supplied into the interior of the burner 14 by means of a fuel supply unit 16. In addition, air L can also be guided to the interior of the burner 14 using an air supply device 18. The fuel-air mixture that forms there can be ignited in a manner not shown, which creates the exhaust gas. The exhaust gas is fed via a supply line 20 from the burner 14 into the catalytic converter 12, where the catalytic converter 12 treats the exhaust gas. After the exhaust gas treatment has been completed, the treated exhaust gas is discharged into the environment of the device 10 through a discharge line 22.

An addition unit 24 is arranged in the supply line 20, with which synthesis gas S can be added to the exhaust gas that has been generated in the burner 14. In addition, a first branch 26 is provided in the supply line 20, from which a bypass line 28 branches off from the supply line 20. In the exemplary embodiment shown, a first control element 30 is arranged in the first branch 26, with which the volume flow of the exhaust gas that flows through the bypass line 28 can be adjusted. As a result, the volume flow of the exhaust gas, which is led to the catalytic converter 12, can also be adjusted. The first control element 30 is designed as a flap 32, which can be opened more or less widely or closed completely. Depending on the position of the flap 32, the exhaust gas coming from the burner 14 can be guided completely or in the desired proportion to the catalytic converter 12. Not shown is an embodiment in which the first actuating element 30 is designed as a throttle valve. The throttle valve or the flap 32 can be arranged at a distance from the first branch 26 in the bypass line 28.

The exhaust gas flowing through the bypass line 28 is passed into the environment of the device 10 without further treatment.

In addition, a first measuring device 34 is arranged in the supply line 20, with which the composition of the exhaust gas in the supply line 20 can be determined. The composition is determined quantitatively, in particular with regard to the hydrocarbons (CmHn), carbon monoxide (CO), carbon dioxide (CO2) and nitrogen oxides (NOx) contained in the exhaust gas, whereby other substances contained in the exhaust gas can also be quantified.

In addition, the device 10 includes a first oxygen probe 36 arranged in the supply line 20, with which the oxygen content of the exhaust gas in the supply line 20 can be determined. With regard to the characterization of the catalytic converter 12, it is less the oxygen content as such that is important than the combustion air ratio λ, which, however, is closely linked to the oxygen content. Furthermore, a first temperature sensor 38 is provided, with which the temperature of the exhaust gas in the supply line 20 can be determined. At this point it should be mentioned that the first measuring device 34, the first oxygen probe 36 and the first temperature sensor 38 are arranged downstream of the first branch 26 but upstream of the catalytic converter 12. The information “downstream” and “upstream” refers to the main flow direction of the exhaust gas within the device 10, which is in the 1 marked with the arrows. In other words, the first temperature sensor 38, the first measuring device 34 and the first oxygen probe 36 are arranged between the first branch 26 and the catalytic converter 12 in the supply line 20. The arrangement of the first temperature sensor 38s, the first measuring device 34 and the first oxygen probe 36 between the first branch 26 and the catalytic converter 12 relative to one another can be freely selected.

A first catalyst temperature sensor 40 ₁ and a second catalyst temperature sensor 40 ₂ are arranged within the catalytic converter 12. The two catalyst temperature sensors 40 ₁ , 40 ₂ serve to determine the temperature of the exhaust gas as it flows through the catalyst 12, but at different positions within the catalyst 12. The number of catalyst temperature sensors 40 ₁ , 40 ₂ is not limited to two, Rather, only one catalyst temperature sensor 40 or more than two catalyst temperature sensors 40 can be provided.

Downstream of the catalytic converter 12, the already mentioned discharge line 22 is provided, with which the exhaust gas treated in the catalytic converter 12 is released the environment of the device 10 can be removed. In the discharge line 22 there is a second branch 42, from which a return line 44 branches off. At least part of the treated exhaust gas can be guided back to the burner 14 using the return line 44. An embodiment in which the return line 44 does not open into the burner 14 but into the supply line 20 is not shown. A second control element 46 is arranged in the second branch 42, with which the proportion of the volume flow of the treated exhaust gas that is to be returned to the burner 14 can be adjusted. In this case, the second actuating element 46 is designed as a flap 48, but can also be designed as a throttle valve or the like. In particular, if the second actuating element 46 is designed as a throttle valve, it can also be arranged at a distance from the second branch 42 in the return line 44. The same can also apply to the flap 48.

Between the catalytic converter 12 and the second branch 42 are a second temperature sensor 50 for determining the temperature of the treated exhaust gas in the discharge line 22, a second oxygen probe 52 for determining the oxygen content of the treated exhaust gas in the discharge line 22 and a second measuring device 54 for determining the composition of the treated exhaust gas is arranged in the discharge line 22. The arrangement of the second temperature sensor 50, the second oxygen probe 52 and the second measuring device 54 relative to one another in the discharge line 22 can be freely selected. The second temperature sensor 50 can be designed to be identical to the first temperature sensor 38 and the two catalyst temperature sensors 40 ₁ , 40 ₂ . Accordingly, the first measuring device 34 can be designed to be identical to the second measuring device and the second oxygen probe 52 to be designed to be identical to the first oxygen probe 36. The first oxygen probe 36 and the second oxygen probe 52 can be designed as a so-called broadband oxygen probe. Broadband oxygen probes allow the combustion air ratio λ to be quantified, which is not possible with jump probes.

In the exemplary embodiment shown, a third temperature sensor 56 is arranged in the return line 44, so that the temperature of the recirculated exhaust gas can also be determined.

A control and/or regulation device with which the device 10 can be operated is not shown.

The device 10 according to the invention can be operated in the following way to characterize a given catalyst 12: In a first mode (“aging mode”), the catalyst 12 is supplied with an exhaust gas which is in the burner 14 using fuel B (petrol or diesel fuel) and Air L has been generated. The addition unit 24 is closed so that no synthesis gas S is supplied to the exhaust gas. No measurement is performed during aging mode. The exhaust gas is completely fed to the catalytic converter 12, for which purpose the flap 32 completely closes the bypass line 28.

Once the relevant aging point has been reached, the device 10 is operated in a second mode (“characterization mode”), in which the synthesis gas S is added to the exhaust gas generated by the burner 14. Upstream of the catalytic converter 12, the composition of the exhaust gas, in particular with regard to the above-mentioned components, is determined with the first measuring device 34, its temperature with the first temperature sensor 38 and the combustion air ratio λ with the first oxygen probe 36.

In addition, the temperature of the exhaust gas flowing through the catalytic converter 12 is determined using the two catalytic converter temperature sensors 40 ₁ , 40 ₂ within the catalytic converter 12. Downstream of the catalytic converter 12, the composition is determined with the second measuring device 54, the temperature with the second temperature sensor 50 and the combustion air ratio λ with the second oxygen probe 52. By comparing the exhaust gas data measured upstream of the catalytic converter 12 with those measured downstream of the catalytic converter 12, an emission conversion rate and/or the MOL at the given aging point can be determined.

In the event that the characterization of the catalyst 12 is to be carried out at the desired aging time for different volume flows or mass flows, the measurement described above can be repeated. For this purpose, the first actuating element 30 is activated accordingly in order to allow a larger or smaller volume flow to flow through the bypass line 28.

In the event that the characterization of the catalyst 12 is to be carried out at the desired aging time for different temperatures, the measurements described above can be repeated. For this purpose, the second actuating element 46 is activated accordingly in order to allow a larger or smaller volume flow to flow through the return line 44. The mass flow and the temperature can be changed independently of each other.

The result is a map of the emission conversion rates and/or the MOL for a specific aging time, depending on the temperature and the volume flow or mass flow.

After the characterization has been completed, the device 10 is operated again in the aging mode until the next aging point is reached. Then the device 10 is switched back to the characterization mode and the catalyst 12 is characterized again and a further map of the emission conversion rates and / or the MOL is determined as a function of the temperature and the volume flow or mass flow, but at a different aging time. The two modes are repeated until the characterization of the catalyst 12 is completed at all desired aging times. Now another catalyst 12 can be characterized in the manner described.

The results can be used, for example, to simulate the aging process, which in turn can be taken into account when developing washcoats. In addition, a corresponding algorithm can be stored in the control electronics of an internal combustion engine so that a message can be issued to the driver when the emission conversion rates fall below a certain value so that the driver can initiate the replacement of the catalytic converter 12.

QUOTES INCLUDED IN THE DESCRIPTION

This list of documents listed by the applicant was generated automatically and is included solely for the better information of the reader. The list is not part of the German patent or utility model application. The DPMA assumes no liability for any errors or omissions.

Cited patent literature

• EP 1521903 A1 [0004]

Claims (9)

Device (10) for characterizing a catalyst at different aging times, comprising - a catalyst to be characterized (12), - a burner (14) for generating exhaust gas, the burner (14) ◯ a fuel supply unit (16) for supplying fuel (B) into the burner (14), and ◯ comprises an air supply device (18) for supplying air (L) into the burner (14), - a supply line (20) for supplying the exhaust gas generated in the burner (14) to the catalytic converter (12), - an addition unit (24) arranged in the supply line (20) for adding synthesis gas (S) to the exhaust gas generated by the burner (14), - a first measuring device (34) arranged in the supply line (20) downstream of the addition unit (24) for determining the composition of the exhaust gas supplied to the catalytic converter (12), - a discharge line (22) for discharging the exhaust gas treated in the catalytic converter (12), and - A second measuring device (54) arranged in the discharge line (22) for determining the composition of the exhaust gas treated by the catalyst (12). Device (10) after Claim 1 , wherein - in the supply line (20) downstream of the addition unit (24) a first oxygen probe (36) for determining the combustion air ratio of the exhaust gas supplied to the catalytic converter (12), and / or - in the discharge line (22) a second oxygen probe (52) are arranged to determine the combustion air ratio of the exhaust gas treated by the catalytic converter (12). Device (10) according to one of the Claims 1 or 2 , wherein - in the supply line (20) downstream of the addition unit (24) a first temperature sensor (38) for determining the temperature of the exhaust gas supplied to the catalytic converter (12), and / or - in the discharge line (22) a second temperature sensor (50) are arranged to determine the temperature of the exhaust gas treated by the catalyst (12). Device (10) according to one of the preceding claims, wherein at least one catalyst temperature sensor (40) is arranged in the catalytic converter (12) for determining the temperature of the exhaust gas flowing through the catalytic converter (12). Device (10) according to one of the preceding claims, wherein a first branch (26) is arranged downstream in the supply line (20), from which a bypass line (28) branches off from the supply line (20), wherein in the first branch (26) or a first adjusting element (30) is arranged in the bypass line (28) for adjusting the volume flow flowing through the bypass line (28). Device (10) according to one of the preceding claims, wherein a second branch (42) is arranged in the discharge line (22), from which a return line (44) branches off, with which the exhaust gas treated by the catalyst (12) is fed to the burner (14). or can be returned to the supply line (20), a second adjusting element (46) being arranged in the second branch (42) or in the bypass line (28) for adjusting the volume flow flowing through the return line (44). Device (10) after Claim 6 , wherein a third temperature sensor (56) for determining the temperature of the recirculated exhaust gas is arranged in the return line (44). Method for operating a device (10) according to one of the preceding claims for characterizing a catalyst (12) at different aging times, comprising the following steps: - Characterizing a catalyst (12), for which the following characterization steps are carried out: ◯ generating exhaust gas by means of the burner (14), with fuel being supplied to the burner (14) with the fuel supply unit (16) and air with the air supply device (18), ◯ Supplying the exhaust gas generated in the burner (14) to the catalytic converter (12) through the supply line (20), ◯ Adding synthesis gas (S) to the exhaust gas generated by the burner (14) with the addition unit (24) into the supply line (20), and ◯ Determining the composition of the exhaust gas supplied to the catalytic converter (12) using the first measuring device (34) and/or the exhaust gas treated by the catalytic converter (12) using the second measuring device (54), or - Aging of the catalyst (12), for which the following aging steps are carried out: ◯ Generating exhaust gas by means of the burner (14), with the burner (14) being supplied with fuel (B) with the fuel supply unit (16) and air (L) with the air supply device (18), and ◯ Supplying the exhaust gas generated in the burner (14) to the catalytic converter (12) through the supply line (20). Computer program product with a program code stored on a computer-readable medium for carrying out the method Claim 8 .

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