JP5809049B2 - Method of using steam reforming catalyst for fuel cell and hydrogen production system - Google Patents

Description

  The present invention relates to a method for using a steam reforming catalyst for a fuel cell and a hydrogen production system. More specifically, the present invention relates to a platinum / rhodium catalyst as a steam reforming catalyst for hydrocarbons for hydrogen production as a fuel for a fuel cell. By arranging a ruthenium-based catalyst layer that is resistant to carbon deposition as a pre-reforming catalyst in the low temperature region of the previous stage and converting heavy hydrocarbons to methane, carbon deposition on platinum / rhodium-based catalysts is prevented. The present invention relates to a method for using a hydrocarbon steam reforming catalyst, a hydrogen production method, and a hydrogen production system using the method for using the hydrocarbon steam reforming catalyst.

  Hydrogen is also used as a fuel for fuel cells, such as polymer electrolyte fuel cells (PEFC). One of the industrial production methods for hydrogen is steam reforming of natural gas, city gas and other hydrocarbons. In the hydrocarbon steam reforming method, a steam reformer is used, and the hydrocarbon is converted into a hydrogen-rich reformed gas by a reforming reaction with steam. The steam reformer is generally composed of a combustion section in which a burner or a combustion catalyst is arranged and a reforming section in which a reforming catalyst is arranged. Hereinafter, the steam reformer is also referred to as “reformer” as appropriate.

  FIG. 1 is a diagram schematically showing a steam reformer. Generally, it is composed of a combustion part (heating part) in which a burner or a combustion catalyst is arranged and a reforming part in which a reforming catalyst is arranged. In the reforming section, the hydrocarbon is changed to a hydrogen-rich reformed gas by a reforming reaction with steam. In the case where heat is supplied from the outside for the progress of the reaction in the reforming section and hydrocarbons are used as raw materials, a temperature of 600 ° C. or higher is required. For this reason, the combustion heat (ΔH) generated by the combustion of the fuel gas in the combustion section (combustion air) is supplied to the reforming section. For example, a noble metal catalyst such as Pt is used as the combustion catalyst.

  FIG. 2 is a diagram for explaining an example of a mode from the supply of hydrocarbon (raw material gas) to PEFC using the steam reformer as described above. Since the reforming catalyst is poisoned by sulfur compounds such as hydrogen sulfide and mercaptan in the raw material gas and deteriorates performance, it is introduced into a desulfurizer to remove those sulfur compounds.

  Since the reforming reaction in the reforming unit is an endothermic reaction, fuel gas such as city gas is burned with air in the combustion unit for the progress, and the generated combustion heat (ΔH) is supplied to the reforming unit. Here, since the fuel supplied to the combustion section is a hydrocarbon-based fuel such as city gas, which is usually the same as hydrocarbons that are changed to reformed gas in the reforming section, in order to distinguish between the two in this specification, The fuel supplied to the combustion section is called fuel gas, and the hydrocarbon supplied to the reforming section is called raw material gas.

  In the reformed gas obtained by reforming in the reforming section, in addition to unreacted hydrocarbon and unreacted water vapor, carbon dioxide and carbon monoxide (CO) are by-produced in addition to hydrogen. About 15% (capacity, hereinafter the same) is included. For this reason, the CO in the reformed gas is supplied to the CO conversion section in order to react with water vapor by a shift reaction and convert it into hydrogen and carbon dioxide. As the steam necessary for this reaction, unreacted residual steam is used in the reforming section.

  The reformed gas exiting from the CO conversion section is composed of hydrogen, carbon dioxide, and CO except for unreacted hydrocarbons and excess steam. Of these, hydrogen is the intended component, but the reformed gas that has passed through the CO conversion section is not completely removed, but contains a small amount of CO. For this reason, the reformed gas is supplied to the CO removal unit to further remove CO. For example, when using PEFC fuel, CO in the reformed gas is reduced to 10 ppm (capacity ppm, the same applies hereinafter) or less, and further to 1 ppm in the CO removal unit.

  Incidentally, the natural gas contains heavy hydrocarbons such as BTX (benzene, toluene, xylene) (Patent Document 1: Japanese Patent Application Laid-Open No. 2007-016149). The liquefied natural gas (LNG) imported into Japan purifies the gas before it is transported by the LNG tanker and removes impurities, so there are very few impurities in city gas that uses LNG as a raw material. It is. However, city gas may contain a certain amount of heavy hydrocarbons such as BTX, and city gas may contain several percent of nitrogen as impurities.

  City gas is also used as a raw material for producing fuel hydrogen for fuel cells. Reforming hydrocarbons such as methane, propane and butane, which are constituents of city gas, produce hydrogen, and use the hydrogen as a fuel for polymer electrolyte fuel cells (PEFC) and solid oxide fuel cells (SOFC). It is intended to be used as As the reforming method, a steam reforming method or a partial combustion method is used.

  However, when producing hydrogen from city gas, if nitrogen is contained in a hydrocarbon fuel gas such as city gas, during the reforming, ammonia is produced from the hydrogen produced by the reforming catalyst and the nitrogen, This becomes a hindrance to the fuel cell reaction and a factor that poisons the fuel cell body. As means for suppressing such ammonia production, methods have been proposed in which a steam reforming catalyst uses a catalyst in which platinum, rhodium, or both of these components are supported (Patent Documents 2 to 5).

  Patent Document 2 (Japanese Patent Laid-Open No. 2005-147483) discloses a solid polymer having a fuel reforming system including a reformer, a CO converter, and a CO selective oxidizer that selectively oxidizes and removes CO. In a type fuel cell (PEFC) power generation system, a PEFC power generation system is described in which stable operation with high cell efficiency is performed over a long period of time by suppressing generation of ammonia that causes deterioration of the PEFC main body.

  That is, a platinum catalyst or rhodium that suppresses ammonia generation activity in each of these catalyst layers from a steam reformer to a CO selective oxidizer that removes CO by a CO selective oxidation reaction of hydrogen-rich gas generated through a CO converter and air. A catalyst or both of these catalysts are used. This suppresses the generation of ammonia, which causes poisoning of the battery body, and further includes a catalyst for removing ammonia on the outlet side of the CO selective oxidizer, so that PEFC can perform stable operation with high battery efficiency over a long period of time. This is a power generation system.

  In Patent Document 3 (Japanese Patent Laid-Open No. 2003-031247), the ammonia concentration in the hydrogen-rich gas obtained by reforming the raw fuel containing nitrogen or the mixture containing raw fuel and nitrogen is used as an ammonia remover. To 5 ppb or less, preferably 0.5 ppb or less. Thereby, it is said that the long-term durability of 90,000 hours or more (that is, 10 years or more) can be secured for PEFC using this as a fuel.

  In Patent Document 4 (Japanese Patent Laid-Open No. 2003-146615), when hydrogen is produced from a hydrocarbon, steam and air by a steam reforming reaction and a partial oxidation reaction, a supported platinum catalyst is used to suppress by-production of ammonia. It is said. Further, Patent Document 5 (Japanese Patent Application Laid-Open No. 2003-132926) discloses a modification for a fuel cell power generation apparatus in which a part of hydrogen gas is passed through an ammonia removing device and then introduced into a desulfurizer. The genitalia are listed.

JP 2007-016149 A JP-A-2005-147483 JP 2003-031247 A JP 2003-146615 A JP 2003-132926 A

Proc SPE / EPA Explor Prod Environ Conf 1997, p.17-27 (1997) − F.D.Skinner and two other authors “Absorption of BTEX and Other Organics and Distribution Between Natural Gas Sweetening Unit Streams” −

  By the way, when heavy hydrocarbons such as BTX are contained in city gas, carbon is deposited on the platinum / rhodium-based reforming catalyst, thereby reducing the catalytic activity. The system reforming catalyst could not be used for city gas containing heavy hydrocarbons.

  A method for using a steam reforming catalyst for hydrogen production that is a fuel for a fuel cell according to the present invention, a hydrogen production method using a hydrogen production apparatus for a fuel cell, and a hydrogen production system for a fuel cell are the first stage of a platinum / rhodium-based steam reforming catalyst. Carbon deposition on platinum / rhodium-based steam reforming catalyst by filling and arranging ruthenium-based catalyst, which is considered to be resistant to carbon deposition, as a pre-reforming catalyst in the low temperature region of the catalyst, and converting heavy hydrocarbons to methane The purpose is to prevent.

  In addition, if nitrogen is contained in the city gas, ammonia is generated, which poisons the fuel cell body such as PEFC and degrades the fuel cell performance. Therefore, it is necessary to suppress the generation of ammonia. In particular, when city gas contains heavy hydrocarbons such as BTX in addition to nitrogen, carbon deposition occurs on the platinum / rhodium-based reforming catalyst, thereby reducing the catalytic activity. Therefore, the platinum / rhodium-based reforming catalyst cannot be used for city gas containing both nitrogen and heavy hydrocarbons.

  In the method for using a steam reforming catalyst for a fuel cell and a hydrogen production system according to the present invention, by using a ruthenium-based catalyst only in a low temperature region upstream of the steam reforming catalyst layer, generation of ammonia can be suppressed. It aims at enabling hydrogen production from city gas containing both nitrogen and heavy hydrocarbons.

The present invention (1) is a method for using a steam reforming catalyst in a fuel cell hydrogen production apparatus in which a CO reforming section and a CO removing section are sequentially connected to a steam reformer including a combustion section and a reforming section. In addition, a ruthenium catalyst layer is arranged as a pre-reforming catalyst that does not convert nitrogen into ammonia in the low temperature region upstream of the platinum / rhodium-based steam reforming catalyst layer, and the heavy hydrocarbon is converted to methane at 350 to 450 ° C. conversion, and then to place the steam reforming catalyst layer of the platinum-rhodium-based, by generating a reformed gas at 450-680 ° C., to prevent carbon deposition on the steam reforming catalyst layer of a platinum-rhodium-based This is a method for using a steam reforming catalyst in a hydrogen production apparatus for a fuel cell.

The present invention (2) is a method for producing hydrogen by a fuel cell hydrogen production apparatus in which a CO reforming unit and a CO removal unit are sequentially connected to a steam reformer including a combustion unit and a reforming unit. A ruthenium catalyst layer is disposed as a pre-reforming catalyst that does not convert nitrogen into ammonia in a low temperature region before the rhodium-based steam reforming catalyst layer, and converts heavy hydrocarbons to methane at 350 to 450 ° C. , and then place the steam reforming catalyst layer of the platinum-rhodium-based, by generating a reformed gas at 450-680 ° C., and features to prevent carbon deposition on the steam reforming catalyst layer of a platinum-rhodium-based This is a hydrogen production method using a hydrogen production apparatus for a fuel cell.

  In the present invention (1) to (2), by using the ruthenium catalyst only in the low temperature region upstream of the platinum / rhodium-based steam reforming catalyst layer, it is possible to suppress the generation of ammonia. It is possible to produce hydrogen from city gas containing both quality hydrocarbons. The temperature range in the low temperature region before the steam reforming catalyst layer is preferably selected in the range of 350 to 450 ° C.

  The present invention (2) is regarded as a hydrogen production method by the fuel cell hydrogen production apparatus, in contrast to the method of using the steam reforming catalyst in the fuel cell hydrogen production apparatus of the present invention (1).

The present invention (3) is a hydrogen production system for a fuel cell in which a CO conversion unit and a CO removal unit are sequentially connected to a steam reformer including a combustion unit and a reforming unit. A ruthenium catalyst layer is disposed as a pre-reforming catalyst that does not convert nitrogen into ammonia in a low temperature region in front of the reforming catalyst layer, and converts heavy hydrocarbons to methane at 350 to 450 ° C. , and then the platinum / rhodium place the steam reforming catalyst layer of the system, by generating the reformed gas at 450-680 ° C., to become and to prevent carbon deposition on the platinum-rhodium-based steam reforming catalyst layer A hydrogen production system for a fuel cell.

  The present invention relates to a hydrogen production method and system in which a CO reforming unit and a CO removing unit are sequentially connected to a steam reformer including a combustion unit and a reforming unit, and the catalyst layer in the reforming unit is divided into two. In addition, a ruthenium catalyst, which is a catalyst resistant to carbon deposition, is arranged as a pre-reforming catalyst in a low temperature region before the platinum / rhodium-based steam reforming catalyst layer, and then the platinum / rhodium-based steam reforming catalyst layer is disposed. By converting heavy hydrocarbons to methane in the ruthenium catalyst, carbon deposition on the platinum / rhodium-based steam reforming catalyst layer can be prevented.

  In this way, by arranging a ruthenium catalyst, which is a catalyst resistant to carbon deposition, as a pre-reforming catalyst in the low temperature region before the platinum / rhodium-based steam reforming catalyst layer, the heavy hydrocarbons are converted to methane. Further, carbon deposition on the platinum / rhodium-based steam reforming catalyst following the ruthenium catalyst can be prevented. In addition, by using a ruthenium catalyst only in the low temperature region upstream of the platinum / rhodium-based steam reforming catalyst layer, it is possible to suppress the generation of ammonia due to nitrogen contained in the city gas. Hydrogen production from city gas containing both hydrocarbons may be possible.

  The present invention (1) is a method of using a steam reforming catalyst in a fuel cell hydrogen production apparatus in which a CO reforming section and a CO removing section are sequentially connected to a steam reformer including a combustion section and a reforming section. . Then, a ruthenium catalyst layer is arranged as a pre-reforming catalyst that does not convert nitrogen into ammonia in a low temperature region in front of the platinum / rhodium-based steam reforming catalyst layer to convert heavy hydrocarbons to methane, and then the platinum -A rhodium-based steam reforming catalyst layer is disposed to generate reformed gas, thereby preventing carbon deposition on the platinum-rhodium-based steam reforming catalyst layer.

  The present invention (2) is a hydrogen production method by a fuel cell hydrogen production apparatus in which a CO conversion unit and a CO removal unit are sequentially connected to a steam reformer including a combustion unit and a reforming unit. Then, a ruthenium catalyst layer is arranged as a pre-reforming catalyst that does not convert nitrogen into ammonia in a low temperature region in front of the platinum / rhodium-based steam reforming catalyst layer to convert heavy hydrocarbons to methane, and then the platinum -A rhodium-based steam reforming catalyst layer is disposed to generate reformed gas, thereby preventing carbon deposition on the platinum-rhodium-based steam reforming catalyst layer.

  In the present invention (1) to (2), by using the ruthenium catalyst only in the low temperature region upstream of the platinum / rhodium-based steam reforming catalyst layer, it is possible to suppress the generation of ammonia. It is possible to produce hydrogen from city gas containing both quality hydrocarbons. The temperature range in the low temperature region before the steam reforming catalyst layer is preferably selected in the range of 350 to 450 ° C.

  The present invention (3) is a fuel cell hydrogen production system in which a CO reforming unit and a CO removing unit are sequentially connected to a steam reformer including a combustion unit and a reforming unit. Then, a ruthenium catalyst layer is arranged as a pre-reforming catalyst that does not convert nitrogen into ammonia in a low temperature region in front of the platinum / rhodium-based steam reforming catalyst layer to convert heavy hydrocarbons to methane, and then the platinum A feature is that carbon deposition on the platinum / rhodium-based steam reforming catalyst layer is prevented by arranging a rhodium-based steam reforming catalyst layer to generate reformed gas.

Here, the platinum / rhodium-based steam reforming catalyst is a steam reforming catalyst containing platinum, rhodium alone or both components of platinum and rhodium as the steam reforming active metal, for example, alumina, silica, titania, zirconia. Further, it is configured in such a manner that a single component of platinum or rhodium or both components of platinum and rhodium are supported as a steam reforming active metal on a powdery or granular carrier made of ceria or the like.
Further, a ruthenium catalyst, that is, a ruthenium steam reforming catalyst, is a steam reforming catalyst containing ruthenium as a steam reforming active metal. It is composed of ruthenium supported as a modified active metal.

  As described above, when city gas contains particularly nitrogen as an impurity, ammonia is generated from nitrogen by the reforming catalyst, which causes poisoning of a fuel cell body such as PEFC. As means for suppressing ammonia production, a method of supporting platinum, rhodium, or both platinum and rhodium components on a steam reforming catalyst has been proposed (Patent Document 2).

By the way, when nitrogen (N ₂ ) is contained in city gas or natural gas, the ruthenium (Ru) -based catalyst converts N ₂ to NH ₃ at a high temperature of 450 to 680 ° C. Moreover, when heavy hydrocarbons, such as BTX, are contained in city gas or natural gas, carbon deposition will arise on a platinum rhodium (Pt-Rh) type catalyst, and catalyst activity will fall. For this reason, it was impossible to use these ruthenium (Ru) -based catalysts and platinum / rhodium-based catalysts for city gas or natural gas containing both nitrogen and heavy hydrocarbons.

FIG. 3 shows the main parts thereof. As shown in FIG. 3A, when city gas or natural gas contains nitrogen (N ₂ ), the ruthenium (Ru) -based catalyst converts N ₂ to NH ₃ at a high temperature of 450 to 680 ° C. In addition, as shown in FIG. 3B, when heavy gas such as BTX is contained in city gas or natural gas, carbon deposition occurs on the platinum / rhodium (Pt—Rh) catalyst, resulting in catalytic activity. Will fall.

  In the method for using a steam reforming catalyst in a hydrogen production apparatus for a fuel cell according to the present invention, a ruthenium catalyst is used as a pre-reforming catalyst that does not convert nitrogen into ammonia in a low temperature region before the platinum / rhodium-based steam reforming catalyst layer. A platinum / rhodium-based steam reforming catalyst layer is formed by arranging a layer to convert heavy hydrocarbons to methane, and then arranging the platinum / rhodium-based steam reforming catalyst layer to generate a reformed gas. This prevents carbon deposition on the top and prevents deterioration of the platinum / rhodium-based steam reforming catalyst.

  In addition, by using a ruthenium-based catalyst only in the low-temperature region upstream of the platinum / rhodium-based steam reforming catalyst layer, it is possible to suppress the generation of ammonia, and a city that contains both nitrogen and heavy hydrocarbons. Hydrogen production from a gas can be made possible. The temperature range of the low temperature region before the steam reforming catalyst layer can be selected preferably in the range of 350 to 450 ° C. FIG. 4 shows those essential portions.

  As described above, the natural gas contains heavy hydrocarbons such as BTX (benzene, toluene, xylene). Natural gas is a combustible gas mainly composed of hydrocarbons produced from underground gas fields, etc., and contains heavy hydrocarbons in addition to hydrogen and light hydrocarbons such as methane, propane, and butane. Yes.

  The liquefied natural gas (LNG) imported into Japan purifies the gas before it is transported by the LNG tanker and removes impurities, so there are very few impurities in city gas that uses LNG as a raw material. It is. On the other hand, city gas may contain heavy hydrocarbons such as BTX. Further, city gas or natural gas may contain several vol% of nitrogen as an impurity, which causes a problem of ammonia generation. Table 1 shows a composition example of natural gas (Non-Patent Document 1).

  Hereinafter, the present invention will be described in more detail based on experimental examples, but the present invention is not limited to these experimental examples.

<Explanation of test equipment and test operation>
FIG. 5 is a diagram for explaining the test apparatus used in this experimental example and its operation. As shown in FIG. 5, the test apparatus includes mass flow controllers: MFC1, MFC2, a vaporizer 21, a reactor 22 including a heater 24, a gas-liquid separator 25, a GC-FID (hydrogen flame ionization detector) 26, and the like. A reforming catalyst 23 is filled in the reactor 22. In FIG. 5, P is a pump, V1 to V4 are on-off valves, and 1 to 11 are fluid conduits. The vaporizer 21 is provided with a heater for heating a mixed flow of natural gas and pure water, but the illustration is omitted.

  In FIG. 5, at the time of the test operation, natural gas (= test gas) is sequentially viewed in the flow direction from the conduit 1 having the on-off valve V1, to the on-off valve V1, mass flow controller: MFC1, conduit 2, vaporizer 21, After passing through the conduit 3, the reactor (= steam reformer) 22 in which the reforming catalyst 23 is disposed, the conduit 4, and the gas-liquid separator 25, the gas is passed through the GC-FID 26.

  On the other hand, at the same time, pure water is introduced into the conduit 2 through the conduit 10, the mass flow controller: MFC2, the conduit 11, the on-off valve: V2, the conduit 12, and the natural gas flowing through the mass flow controller: MFC1. To mix. A mixed flow of natural gas and pure water is introduced into the vaporizer 21 where pure water is converted into water vapor and introduced into the reactor 22.

  The reactor 22 is heated to the reaction temperature by the heater 24 during its operation. The temperature is usually 450-680 ° C. (450 ° C. at the inlet and 680 ° C. at the outlet). In the reactor 22, a reformed gas mainly composed of hydrogen, carbon monoxide or the like is generated by steam reforming of natural gas by the catalytic action of the reforming catalyst 23.

The produced reformed gas is introduced into the gas-liquid separator 25 through the conduit 4, cooled by indirect heat exchange with the refrigerant, and circulated to the GC-FID 26 through the conduits 6 and 7, the on-off valve V 4 and the conduit 8. Ammonia generating reformed gas (NH ₃₎ concentration was measured by JIS K 009 9.

  FIG. 5B shows a mode in which the reforming catalyst is arranged in two stages (that is, in two layers) in the reactor 22 for testing. As shown in FIG. 5B, the reactor 22 is arranged in two layers of the reforming catalyst 23 (part 1) and the reforming catalyst 23 (part 2). In the test in this mode, as shown in FIG. 4, a Ru-based reforming catalyst layer is disposed in the previous stage, and a Pt—Rh-based reforming catalyst layer is disposed in the subsequent stage. The test in this arrangement is a test corresponding to the embodiment of the present invention.

<Experimental example 1: BTX decomposition test using reforming catalyst>
The test apparatus of FIG. 5 was used, and the test was performed by the aforementioned test operation. A city gas containing BTX was used as a test gas, and a BTX decomposition performance test with a pre-reforming catalyst: a ruthenium-based catalyst (manufactured by Tanaka Kikinzoku Kogyo Co., Ltd .: TRC10-2) was performed. In FIG. 5A, a ruthenium-based pre-reforming catalyst was filled and arranged as the reforming catalyst 23 and tested. The experimental conditions were GHSV = 2,000 h ⁻¹ , catalyst layer temperature: inlet = 350 ° C., outlet = 450 ° C., S / C = 2.8. Table 2 shows the results.

  As shown in Table 2, the BTX concentration at the outlet of the pre-reforming catalyst was “ND”, that is, the detection lower limit value or less as a result of gas analysis by GC-FID (detection lower limit value = about 0.1 ppm). The result shows that BTX is decomposed by the pre-reforming catalyst. As described above, since BTX is decomposed by the pre-reforming catalyst, it is possible to prevent BTX from flowing into the Pt—Rh-based reforming catalyst layer disposed at the subsequent stage of the ruthenium-based pre-reforming catalyst layer. Thereby, precipitation of carbon can be prevented.

<Experimental example 2: Ammonia production amount confirmation test by reforming catalyst>
Using the test apparatus of FIG. 5B, the test was performed by the above-described test operation. A steam reforming reaction was carried out using a city gas mixed with nitrogen as a test gas, and a confirmation test of the amount of ammonia produced under each condition was carried out. In FIG. 5 (b), the ruthenium pre-reforming catalyst is filled and arranged as the reforming catalyst 23 (part 1), and the platinum-rhodium based reforming catalyst is filled and arranged as the reforming catalyst 23 (part 2). And tested. The experimental conditions and the results are shown in Table 3.

  Under the conventional one-stage reforming conditions of ruthenium catalyst (catalyst layer temperature: inlet = 450 ° C., outlet = 650 ° C.), about 25-35 ppm of ammonia is generated at a nitrogen concentration of 4.5 vol%, whereas platinum-rhodium In the system catalyst, even when the nitrogen concentration was 27 vol%, the ammonia concentration was very small as 0.40 ppm.

  Even in the case of a ruthenium-based catalyst, under the pre-reforming conditions (catalyst layer temperature: inlet = 450 ° C., outlet = 550 ° C.), the amount of ammonia produced is about 4 to 12 ppm at a nitrogen concentration of 4.5 vol%. When a platinum / rhodium catalyst is used for the catalyst and the main reforming, ammonia production can be suppressed as compared with the prior art.

More specifically, as shown in Table 3, in the ruthenium-based catalyst (catalyst layer temperature: inlet = 400 ° C., outlet = 650 ° C.), (1) nitrogen concentration 4.5 vol%, SV = 140 h ⁻¹ and ammonia concentration 34.20 ppm (2) A nitrogen concentration of 4.5 vol%, SV = 450 h ⁻¹ and an ammonia concentration of 25.67 ppm are shown.

On the other hand, in the ruthenium-based catalyst (catalyst layer temperature: inlet = 450 ° C., outlet = 550 ° C.), (3) nitrogen concentration 4.5 vol%, SV = 600 h ⁻¹ , ammonia concentration 11.84 ppm, (4) A nitrogen concentration of 4.5 vol%, SV = 2,000 h ⁻¹ , an ammonia concentration of 4.01 ppm, and a catalyst layer temperature: inlet = 450 ° C., outlet = 550 ° C. indicates that a good ammonia production suppression effect can be achieved. .

On the other hand, in a platinum-rhodium catalyst (catalyst layer temperature: inlet = 450 ° C., outlet = 680 ° C.), (5) ammonia with an ammonia concentration of 0.40 ppm is generated at a nitrogen concentration of 27 vol% and SV = 300 h ^−1. -The rhodium-based catalyst had a very small ammonia concentration of 0.40 ppm even at a nitrogen concentration of 27 vol%.

FIG. 1 is a diagram schematically showing a steam reformer. FIG. 2 is a diagram showing an example of a mode from the supply of hydrocarbon (raw material gas) to PEFC using the steam reformer as shown in FIG. FIG. 3 is a diagram for explaining the presence / absence of NH ₃ generation depending on the catalyst used and the temperature conditions during reforming of city gas containing nitrogen. FIG. 4 is a diagram illustrating the positional relationship between the Ru catalyst and the Pt—Rh catalyst in the present invention. FIG. 5 is a diagram for explaining the test apparatus and operation used in this experimental example.

V1 to V4 open / close valve

Claims (3)

A method for using a steam reforming catalyst in a hydrogen production apparatus for a fuel cell comprising a CO reforming unit and a CO removing unit sequentially connected to a steam reformer including a combustion unit and a reforming unit, comprising: A ruthenium catalyst layer is arranged as a pre-reforming catalyst that does not convert nitrogen into ammonia in a low temperature region in front of the steam reforming catalyst layer, and converts heavy hydrocarbons to methane at 350 to 450 ° C. place the steam reforming catalyst layer rhodium, by generating a reformed gas at four hundred and fifty to six hundred and eighty ° C., and wherein the preventing carbon deposition on the platinum-rhodium-based steam reforming catalyst layer A method for using a steam reforming catalyst in a hydrogen production apparatus for a fuel cell. A platinum / rhodium-based steam reforming catalyst comprising a hydrogen reforming apparatus for a fuel cell comprising a CO reforming section and a CO removing section sequentially connected to a steam reformer including a combustion section and a reforming section. A ruthenium catalyst layer is disposed as a pre-reforming catalyst that does not convert nitrogen into ammonia in a low temperature region in front of the layer, and heavy hydrocarbons are converted to methane at 350 to 450 ° C. , and then the platinum-rhodium-based water vapor place the reforming catalyst layer, by generating a reformed gas at 450-680 ° C., hydrogen for fuel cells, characterized by preventing carbon deposition on the platinum-rhodium-based steam reforming catalyst layer A hydrogen production method using a production apparatus. A hydrogen production system for a fuel cell in which a CO reforming unit and a CO removing unit are sequentially connected to a steam reformer including a combustion unit and a reforming unit, and is a front stage of a platinum / rhodium-based steam reforming catalyst layer. A ruthenium catalyst layer is arranged as a pre-reforming catalyst that does not convert nitrogen into ammonia in a low-temperature region, heavy hydrocarbons are converted to methane at 350 to 450 ° C. , and then the platinum / rhodium-based steam reforming catalyst layer was placed, by generating a reformed gas at from 450 to 680 ° C., hydrogen for a fuel cell characterized by comprising as prevent carbon deposition on the platinum-rhodium-based steam reforming catalyst layer Manufacturing system.

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