JP2018009492A - Deterioration diagnostic method and deterioration diagnostic device for fuel reforming catalyst - Google Patents

Abstract

PROBLEM TO BE SOLVED: To detect deterioration of a fuel reforming catalyst 18 before regeneration of an upstream end 31a side portion of a catalyst carrier 31 becomes impossible.SOLUTION: As a fuel reforming system for supplying hydrogen to a combustion chamber, a fuel reforming catalyst 18 and a fuel injection valve 19 for reformed fuel are disposed in an EGR passage of an internal combustion engine. A catalyst temperature sensor 27 is provided in the fuel reforming catalyst 18. Based on a temporal change of a temperature decline caused by heat absorption reaction during reforming, a diagnosis of deterioration is made. The fuel reforming catalyst 18 has a catalyst volume twice as large as a minimum catalyst volume required for reforming. In response to this characteristic, a temperature measurement point 27a of the catalyst temperature sensor 27 is disposed in a range of up to a half from an upstream end 31a of a catalyst carrier 31 and on the downstream side of an oxidation reaction region L1 in the vicinity of the upstream end 31a.SELECTED DRAWING: Figure 2

Description

  According to the present invention, a fuel reforming catalyst and a fuel injection valve for reforming fuel for supplying fuel to the fuel reforming catalyst from the upstream side are provided in an EGR passage that recirculates a part of the exhaust gas of the internal combustion engine to the intake system. More particularly, the present invention relates to a technique for diagnosing deterioration of a fuel reforming catalyst.

  In Patent Document 1, as a fuel reforming catalyst deterioration diagnosis device provided in an EGR passage, the temperature of the gas flowing into the fuel reforming catalyst (catalyst inlet side temperature) upstream and downstream of the fuel reforming catalyst is disclosed. An inlet side temperature sensor that detects the temperature and an outlet side temperature sensor that detects the temperature of the gas flowing out of the fuel reforming catalyst (catalyst outlet side temperature) are arranged to degrade the temperature difference between the catalyst outlet side temperature and the catalyst inlet side temperature A technique for performing deterioration determination by comparing with a determination threshold is disclosed. For example, when the fuel reforming catalyst is an endothermic reaction catalyst, the temperature at the catalyst outlet side is lower than the temperature at the catalyst inlet side when it is not deteriorated. Since the temperature approaches the temperature, the temperature difference becomes smaller than the deterioration determination threshold value, and it is determined as deterioration.

JP 2012-241608 A

  Since fuel is given to the fuel reforming catalyst from the upstream side, deterioration of the catalyst mainly due to sticking of sulfur components and solid carbon deposition proceeds gradually from the upstream end of the fuel reforming catalyst toward the downstream side. To do. On the other hand, the catalyst volume (or catalyst capacity) of the fuel reforming catalyst is generally designed with a sufficient margin for the minimum catalyst volume required for fuel reforming of a required amount of fuel, for example, twice the minimum catalyst volume. It is common to have a degree of catalyst volume.

  Therefore, as in Patent Document 1, there is a margin in the deterioration determination based on the temperature difference between the catalyst outlet side temperature and the catalyst inlet side temperature (that is, the temperature change of the gas that has passed through the entire length of the fuel reforming catalyst). As long as the entire catalyst volume is not deteriorated, the deterioration cannot be detected. When the entire catalyst volume deteriorates and is diagnosed as being deteriorated based on the temperature difference, the upstream end portion of the fuel reforming catalyst that is most deteriorated has a catalytic function due to the regeneration process. It will deteriorate to the extent that it cannot be revived.

  The fuel reforming catalyst deterioration diagnosis method according to the present invention is based on the premise that the fuel reforming catalyst has a catalyst volume N times the minimum catalyst volume required for fuel reforming. A catalyst temperature sensor is arranged upstream of the position 1 / N from the upstream end of the catalyst carrier of the catalyst, and deterioration of the fuel reforming catalyst is judged based on the catalyst carrier temperature indicated by the catalyst temperature sensor during reforming. It is characterized by doing. N is a value larger than 1.

  Since the fuel reforming via the fuel reforming catalyst in the EGR passage is mainly an endothermic reaction, the catalyst carrier temperature indicated by the catalyst temperature sensor is lowered by the endothermic reaction when the fuel reforming catalyst is not deteriorated. On the other hand, when the fuel reforming catalyst deteriorates, the catalyst carrier temperature becomes relatively higher than when it does not deteriorate. Therefore, it is possible to determine the deterioration by comparing the detected catalyst carrier temperature with the deterioration determination temperature according to the inlet gas temperature or the engine operating condition or the catalyst carrier temperature measured in the past.

  Here, assuming that the fuel reforming catalyst has a catalyst volume that is, for example, twice the minimum catalyst volume, most of the catalytic action on the reforming fuel supplied from the upstream side is upstream in the longitudinal direction of the catalyst carrier. It is done in half (or less than half) area. Therefore, by disposing the catalyst temperature sensor within this range and determining the deterioration from the detected temperature, it is possible to diagnose the deterioration before the deterioration proceeds excessively at the upstream end of the catalyst carrier.

  According to the present invention, it is possible to detect deterioration before the entire fuel reforming catalyst deteriorates as in the prior art, and to prevent the upstream end portion where deterioration is most advanced from becoming impossible to regenerate. Can do.

BRIEF DESCRIPTION OF THE DRAWINGS The structure explanatory drawing which shows the structure of the internal combustion engine provided with the fuel reforming system. Explanatory drawing of the temperature measuring point of the catalyst temperature sensor in a fuel reforming catalyst. (A)-(d) is a graph which shows the time-dependent change of the measurement temperature in the AD point of FIG. 2, respectively. The flowchart which shows an example of a process of deterioration diagnosis. The flowchart which shows the example from which the process of deterioration diagnosis differs.

  Hereinafter, an embodiment of the present invention will be described in detail with reference to the drawings.

  FIG. 1 is an explanatory diagram showing a system configuration of an internal combustion engine 1 having a fuel reforming system to be diagnosed according to the present invention. The internal combustion engine 1 is a spark ignition type internal combustion engine using, for example, gasoline as fuel, and includes a fuel injection valve 3 that injects fuel supplied from the fuel tank 2 toward, for example, an intake port of each cylinder. The intake passage 4 of the internal combustion engine 1 is provided with an air flow meter 5 for measuring the amount of intake air and a throttle valve 6. In the illustrated example, a turbocharger 7 including a mechanical supercharger or a turbocharger compressor is shown downstream of the throttle valve 6, but the supercharger 7 is not necessarily essential. Between the supercharger 7 and the internal combustion engine 1, a hydrogen sensor 8 for detecting a hydrogen component in the intake air is provided. The internal combustion engine 1 includes a spark plug 9 in each cylinder.

  An exhaust gas purification catalyst 12 using a three-way catalyst for purifying exhaust gas is provided in the exhaust passage 11 of the internal combustion engine 1. An air-fuel ratio sensor 13 is disposed upstream of the exhaust purification catalyst 12, and an oxygen sensor 14 is disposed downstream of the exhaust purification catalyst 12. The engine controller 15 performs known air-fuel ratio feedback control based on the detection signals of the air-fuel ratio sensor 13 and the oxygen sensor 14.

  Between the exhaust passage 11 and the intake passage 4 of the internal combustion engine 1, an EGR passage 17 that recirculates part of the exhaust gas of the internal combustion engine 1 from the exhaust passage 11 to the intake passage 4 is provided. The EGR passage 17 branches from the exhaust passage 11 on the upstream side of the exhaust purification catalyst 12 and joins the intake passage 4 between the throttle valve 6 and the supercharger 7.

  The EGR passage 17 is provided with a fuel reforming catalyst 18 that forms the main part of the fuel reforming system. The fuel reforming catalyst 18 is provided with a reforming fuel upstream of the fuel reforming catalyst 18. A fuel injection valve 19 for reformed fuel for supplying the fuel is provided together with the mixer 20. In this embodiment, the reforming fuel injection valve 19 injects and supplies gasoline in the fuel tank 2 as reforming fuel, but reforms liquid hydrocarbon fuel different from the fuel supplied to the internal combustion engine 1. It can also be used as a fuel. The fuel reforming catalyst 18 is obtained by coating a monolith honeycomb catalyst carrier with a catalyst slurry containing, for example, a rhodium-based catalyst metal and firing it, and using hydrocarbons and heat contained in exhaust gas (EGR gas) to generate hydrocarbons. Generate hydrogen from fuel.

  The EGR passage 17 further includes a water-cooled or air-cooled EGR gas cooler 21 for cooling the EGR gas, and an exhaust gas recirculation for controlling the EGR rate in accordance with the target EGR rate at a position downstream of the fuel reforming catalyst 18. And a control valve 22. Further, a hydrogen sensor 23 for detecting a hydrogen component in the EGR gas is provided between the fuel reforming catalyst 18 and the EGR gas cooler 21, and between the EGR gas cooler 21 and the exhaust gas recirculation control valve 22, An oxygen sensor 24 is provided. The hydrogen sensor 23 and the oxygen sensor 24 are used together with the hydrogen sensor 8 in the intake passage 4 to control the amount of hydrogen supplied to the combustion chamber by fuel reforming.

  The temperature of the gas flowing into the fuel reforming catalyst 18 via the mixer 20 (inlet gas temperature Tin) is detected between the inlet of the fuel reforming catalyst 18, specifically between the fuel reforming catalyst 18 and the mixer 20. An inlet gas temperature sensor 26 is disposed. The fuel reforming catalyst 18 is provided with a catalyst temperature sensor 27 for detecting the catalyst carrier temperature at a specific position. The inlet gas temperature sensor 26 and the catalyst temperature sensor 27 are used for determining whether or not the temperature state of the fuel reforming catalyst 18 is a state in which the fuel can be reformed. Used for deterioration diagnosis.

  In the internal combustion engine 1 equipped with the fuel reforming system as described above, stable combustion at a high EGR rate is achieved by adding hydrogen by fuel reforming at the time of exhaust gas recirculation. That is, in the engine controller 15, the target EGR rate is set in advance in the form of a map using the operating conditions of the internal combustion engine 1, that is, the load and the rotational speed as parameters, and the exhaust gas recirculation control valve is set so as to realize this target EGR rate. The opening degree of 22 is controlled. In the region where the target EGR rate is higher than a certain level, the reforming fuel is supplied from the reforming fuel injection valve 19 to the fuel reforming catalyst 18, and the steam, heat and fuel reforming contained in the EGR gas are supplied. Hydrogen is produced from the reforming fuel by utilizing the catalytic action of the catalyst 18. This hydrogen merges with fresh air in the intake passage 4 together with the EGR gas, and is introduced into the combustion chamber. Since the combustion speed in the combustion chamber is increased by introducing hydrogen, stable combustion at a high EGR rate can be realized. The amount of the reforming fuel is set so that the total amount combined with the amount of fuel from the fuel injection valve 3 of the internal combustion engine 1 can realize the stoichiometric air-fuel ratio.

  Here, the fuel reforming catalyst 18 is gradually deteriorated, that is, the catalyst performance is deteriorated due to adhesion of sulfur components contained in the fuel to the catalyst layer or deposition of solid carbon. Therefore, the engine controller 15 repeatedly executes the deterioration diagnosis of the fuel reforming catalyst 18 at an appropriate timing, and when it is determined to be deteriorated, executes a predetermined regeneration process for removing sulfur components and solid carbon.

  Hereinafter, the deterioration diagnosis of the fuel reforming catalyst 18 will be described in more detail.

  First, FIG. 2 is an explanatory diagram for explaining a temperature measuring point 27 a of the catalyst temperature sensor 27 provided in the fuel reforming catalyst 18. In this example, the fuel reforming catalyst 18 has a catalyst volume that is twice the minimum catalyst volume required for reforming the required amount of fuel. In other words, the required amount of reforming fuel (that is, the required amount of hydrogen) under each operating condition is determined in relation to the target EGR rate that is determined from the load and the rotational speed, and the maximum required reforming among the operating conditions. The catalyst volume (or catalyst capacity) that can cover the amount of quality fuel is the minimum catalyst volume. The fuel reforming catalyst 18 actually used for this minimum catalyst volume has a catalyst volume with a sufficient margin for ensuring robustness, for example, a catalyst volume twice as large as the minimum catalyst volume. Designed. In the fuel reforming catalyst 18 having a catalyst volume that is twice the minimum catalyst volume in this way, the temperature measuring point 27a of the catalyst temperature sensor 27 is more than a position that is ½ from the upstream end 31a of the catalyst carrier 31. Arranged upstream.

  In other words, in the fuel reforming catalyst 18 having a catalyst volume twice the minimum catalyst volume as described above, theoretically, in the stage where no catalyst deterioration has occurred, the fuel reforming is performed in the region on the upstream side 1/2. In order to diagnose deterioration from the temperature change associated with the catalytic reaction in this region, it is necessary to measure at least the temperature of the catalyst carrier upstream from the position ½ from the upstream end 31a. There is.

  Graphs (a), (b), (c), and (d) in FIG. 3 are obtained at points A, B, C, and D in FIG. 2 when a deterioration durability test of the fuel reforming catalyst 18 is performed. It shows the change in temperature. Here, the fuel reforming is continued while the operating conditions of the internal combustion engine 1, the EGR rate, the amount of reforming fuel, etc. are kept constant, and the temperatures at the respective points (the temperature of the catalyst carrier, the point at points A, B, and C) D is the gas temperature). The horizontal axis of each graph is the operation time. Point A is at a position close to the upstream end 31a of the catalyst carrier 31, point B is at the center in the longitudinal direction of the catalyst carrier 31 (ie 1/2), and point C is downstream of 1/2. In the side position. Point D measures the temperature of the outlet gas that has passed through the catalyst carrier 31.

  As shown in the graph (a), at a position close to the upstream end 31a of the catalyst carrier 31, the catalyst carrier temperature is higher than the inlet gas temperature Tin, and the reformed fuel supplied from the reforming fuel injection valve 19 is supplied. This shows that the fuel used for oxidation has undergone an oxidation reaction. Here, there is little change in temperature over time.

  On the other hand, at the point B, as shown in the graph (b), the catalyst carrier temperature is lower than the inlet gas temperature Tin due to the endothermic reaction accompanying the fuel reforming. The catalyst carrier temperature at this point B approaches the inlet gas temperature Tin from a certain stage as time passes, that is, with the progress of deterioration due to adhesion or deposition of sulfur components or solid carbon, and the upstream side (for example, point Under the influence of the high catalyst carrier temperature in A), it eventually becomes higher than the inlet gas temperature Tin. This means that no endothermic reaction occurs due to deterioration (particularly within the range from the upstream end 31a to the point B of the catalyst carrier 31). Therefore, it is possible to determine the deterioration of the fuel reforming catalyst 18 based on the catalyst carrier temperature at this point B. For example, at the time t1 when the catalyst carrier temperature becomes equal to the inlet gas temperature Tin, it can be considered that the catalyst existing in the range from the upstream end 31a to the point B has already deteriorated.

  On the other hand, at the point C downstream of the 1/2 position, as shown in the graph (c), the state where the catalyst carrier temperature is lower than the inlet gas temperature Tin is longer due to the endothermic reaction accompanying fuel reforming. Continue for hours. For example, the catalyst carrier temperature is lower than the inlet gas temperature Tin after the time t1. This means that the endothermic reaction is maintained by the catalyst existing downstream from the point B. That is, although the deterioration has progressed considerably in the vicinity of the upstream end 31a of the catalyst carrier 31, the temperature at the point C, which is the catalyst carrier temperature of the portion corresponding to the catalyst volume that is a margin beyond the minimum catalyst volume, is significant. Show no change.

  Further, as shown in the graph (d), the temperature at the point D, which is the outlet gas temperature, continues to be lower than the inlet gas temperature Tin for a long time due to the endothermic reaction accompanying fuel reforming. That is, unless all of the fuel reforming catalyst 18 having a catalyst volume twice the minimum catalyst volume loses the catalytic reaction, an endothermic reaction is caused by the downstream catalyst, so the outlet gas temperature is higher than the inlet gas temperature Tin. Continue to show low temperature. Therefore, the temperature at the point D does not show a significant change until the deterioration progresses considerably on the upstream end 31a side where the reforming fuel is supplied.

  In other words, if the deterioration determination is performed based on the temperature at the point C or the point D exceeding the range corresponding to the minimum catalyst volume, the endothermic reaction by the catalyst, that is, the upstream end 31a side where the deterioration starts earliest, that is, The reforming operation is continued for a longer time after the reforming reaction is lost. Therefore, even if deterioration is judged and catalyst regeneration processing (for example, desorption of sulfur components and solid carbon by forced reduction treatment or oxidation treatment) is started, the catalytic action may not be recovered in the portion on the upstream end 31a side. There is.

  Therefore, the temperature measuring point 27 a of the catalyst temperature sensor 27 for deterioration diagnosis needs to be at least upstream of the position in the longitudinal direction of the catalyst carrier 31. Further, in order not to cause excessive deterioration of the portion on the upstream end 31a side, it is desirable to measure the catalyst carrier temperature on the upstream side as much as possible within a range of 1/2 from the upstream end 31a.

  On the other hand, as shown in the graph (a), the oxidation reaction of the reforming fuel occurs in the vicinity of the upstream end 31a of the catalyst carrier 31, and in this oxidation reaction region, the deterioration is judged based on the temperature change over time. Difficult to do.

  Therefore, as shown in FIG. 2, if the range from the upstream end 31a of the catalyst carrier 31 to the length L1 is the oxidation reaction region, the temperature measuring point 27a can be arranged downstream of the oxidation reaction region L1. desirable. That is, the distance L from the upstream end 31a to the temperature measuring point 27a is within the range of exceeding the oxidation reaction region L1 and ½ of the total length of the catalyst carrier 31. In this range, it is desirable to be as upstream as possible. In one example, the temperature measuring point 27a of the catalyst temperature sensor 27 is set at the boundary position of the oxidation reaction region L1. The oxidation reaction region L1 can be defined as a region where the temperature of the catalyst carrier becomes higher than the inlet gas temperature during reforming, and this region varies depending on the amount of reforming fuel and the like. A region that extends to the side is determined in advance as an oxidation reaction region L1, and a temperature measuring point 27a is arranged downstream of the oxidation reaction region L1.

  FIG. 4 is a flowchart showing an example of the deterioration diagnosis process executed by the engine controller 15. The processing of this flowchart is executed when predetermined diagnostic conditions are satisfied, for example, on condition that engine operating conditions such as load and rotation speed satisfy predetermined conditions and a predetermined time has passed since the previous diagnosis, First, in step 1, the operation mode of the reforming system is set to a diagnostic mode. As a result, for example, the EGR rate and the amount of reforming fuel supplied from the reforming fuel injection valve 19 are controlled within a predetermined range suitable for diagnosis.

  While operating the reforming system in such a diagnostic mode, in step 2, the catalyst carrier temperature Tbed detected by the catalyst temperature sensor 27 is compared with the deterioration determination temperature Tsh. If the detected catalyst carrier temperature Tbed is higher than the deterioration determination temperature Tsh, it is determined that the catalyst has deteriorated, and a predetermined catalyst regeneration mode in step 3 is executed. If the catalyst carrier temperature Tbed is equal to or lower than the deterioration determination temperature Tsh, it is determined that the catalyst has not yet deteriorated, the diagnosis mode is terminated, and the routine shifts to the normal operation mode in Step 4.

  In one example, the deterioration determination temperature Tsh is determined based on the inlet gas temperature Tin detected by the inlet gas temperature sensor 26. The value of the inlet gas temperature Tin itself may be used as the deterioration determination temperature Tsh, or the deterioration determination temperature Tsh may be obtained by appropriately modifying the inlet gas temperature Tin.

  In another example, the deterioration determination temperature Tsh is a value given in advance in the form of a map or the like for each engine operating condition (in other words, the operating condition of the reforming system). That is, the catalyst carrier temperature serving as a reference for non-deterioration is used as the deterioration determination temperature Tsh.

  Therefore, as shown in the graph (b) of FIG. 3, it is possible to detect the deterioration of the fuel reforming catalyst 18 at an early stage and start the regeneration process before the upstream end 31a side portion becomes unrecyclable. .

  FIG. 5 is a flowchart showing another example of the deterioration diagnosis process executed by the engine controller 15. The processing of this flowchart is also executed when predetermined diagnostic conditions are satisfied, for example, on condition that engine operating conditions such as load and rotation speed satisfy predetermined conditions and a predetermined time has elapsed since the previous diagnosis. First, in step 11, the operation mode of the reforming system is set to the diagnosis mode. As a result, for example, the EGR rate and the amount of reforming fuel supplied from the reforming fuel injection valve 19 are controlled within a predetermined range suitable for diagnosis.

  Next, at step 12, the catalyst carrier temperature Tbed detected by the catalyst temperature sensor 27 at the time of the current diagnosis is stored. In step 13, the current catalyst carrier temperature Tbed is compared with the catalyst carrier temperature Tbedold at the previous diagnosis. If the current catalyst carrier temperature Tbed is higher than the previous catalyst carrier temperature Tbedold, it is determined that the catalyst has deteriorated, and a predetermined catalyst regeneration mode in step 14 is executed. If the current catalyst carrier temperature Tbed is equal to or lower than the previous catalyst carrier temperature Tbedold, it is determined that the catalyst has not yet deteriorated, the diagnostic mode is terminated, and the routine proceeds to the normal operation mode in Step 15.

  That is, when the catalyst carrier temperature Tbed at the temperature measuring point 27a of the catalyst temperature sensor 27 changes in the increasing direction, it is diagnosed as deterioration. In order to avoid erroneous diagnosis, the temperature obtained by adding a minute amount ΔT to the previous catalyst carrier temperature Tbedold may be compared with the current catalyst carrier temperature Tbed.

  As mentioned above, although one Example of this invention was described in detail, the value of ratio N of the minimum catalyst volume and an actual catalyst volume is arbitrary values larger than one. For example, if the catalyst volume of the fuel reforming catalyst 18 is three times the minimum catalyst volume, the temperature measuring point 27a of the catalyst temperature sensor 27 is located upstream of the position that is 1/3 from the upstream end 31a of the catalyst carrier 31. Need to be placed.

DESCRIPTION OF SYMBOLS 1 ... Internal combustion engine 2 ... Fuel tank 3 ... Fuel injection valve 4 ... Intake passage 5 ... Air flow meter 6 ... Throttle valve 11 ... Exhaust passage 12 ... Exhaust purification catalyst 15 ... Engine controller 17 ... EGR passage 18 ... Fuel reforming catalyst 19 ... Fuel injection valve for reformed fuel 21 ... EGR gas cooler 22 ... Exhaust gas recirculation control valve 26 ... Inlet gas temperature sensor 27 ... Catalyst temperature sensor

Claims (7)

An internal combustion engine comprising a fuel reforming catalyst and a fuel injection valve for reformed fuel for supplying fuel to the fuel reforming catalyst from an upstream side in an EGR passage that recirculates part of the exhaust gas of the internal combustion engine to the intake system In the institution
The fuel reforming catalyst has a catalyst volume N times the minimum catalyst volume required for fuel reforming,
A catalyst temperature sensor is disposed upstream of a position of 1 / N from the upstream end of the catalyst support of the fuel reforming catalyst,
A method for diagnosing deterioration of a fuel reforming catalyst, wherein deterioration of the fuel reforming catalyst is determined based on a catalyst carrier temperature indicated by the catalyst temperature sensor during reforming.   The range of the oxidation reaction region on the upstream end side where the catalyst carrier temperature becomes higher than the inlet gas temperature during reforming is determined in advance, and the catalyst temperature sensor is arranged downstream of the oxidation reaction region. Item 2. A method for diagnosing deterioration of a fuel reforming catalyst according to Item 1.   3. The method for diagnosing deterioration of a fuel reforming catalyst according to claim 2, wherein the catalyst temperature sensor is arranged at a boundary position of the oxidation reaction region.   The method for diagnosing deterioration of a fuel reforming catalyst according to any one of claims 1 to 3, wherein the N is 2.   5. The method for diagnosing deterioration of a fuel reforming catalyst according to claim 1, wherein the deterioration is determined when the catalyst carrier temperature detected by the catalyst temperature sensor is higher than a deterioration determination temperature.   2. The catalyst carrier temperature detected by the catalyst temperature sensor is compared with a past catalyst carrier temperature under the same operating condition, and it is determined that the temperature is deteriorated when a predetermined temperature rise is indicated. The method for diagnosing deterioration of a fuel reforming catalyst according to any one of -4. An internal combustion engine comprising a fuel reforming catalyst and a fuel injection valve for reformed fuel for supplying fuel to the fuel reforming catalyst from an upstream side in an EGR passage that recirculates part of the exhaust gas of the internal combustion engine to the intake system In the institution
Arranged upstream from the upstream end of the catalyst carrier of the fuel reforming catalyst, where N / N is a ratio of the catalyst volume of the fuel reforming catalyst to the minimum catalyst volume required for fuel reforming. A catalyst temperature sensor,
A fuel reforming catalyst deterioration diagnosis device comprising: a control device that compares the catalyst carrier temperature detected by the catalyst temperature sensor with a deterioration determination temperature or a past catalyst carrier temperature to determine the deterioration of the fuel reforming catalyst. .

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