JP2012210620A - Reforming catalyst for producing hydrogen, hydrogen producing apparatus using the catalyst and fuel cell system - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a reforming catalyst for producing hydrogen which is inexpensive, highly durable and capable of efficiently producing hydrogen under wide conditions in hydrogen production of a fuel cell system using hydrogen resources such as hydrocarbon as raw materials.SOLUTION: The reforming catalyst for producing hydrogen includes an inorganic composite oxide carrier including alumina and carrying a rare earth metal oxide and an alkaline earth metal oxide, and nickel and a platinum group metal are carried on this carrier. This catalyst carries a nickel and a platinum group metal on the same carrier, and includes rhodium as the platinum group metal. When line analysis of rhodium is conducted in the carrier diameter direction passing the center of the catalyst cross section by using an electron probe microanalyzer (EPMA), the ratio of characteristic X-rays intensities of the rhodium detected within the range from the outer surface of the carrier to the distance of ≤10% of the carrier diameter to the characteristic X-rays intensities of all the rhodium detected is ≥90%. Also, the ratio of the characteristic X-rays intensities of the rhodium detected within the range from the outer surface of the carrier to the distance of ≤20% of the carrier diameter is ≥95%.

Description

  The present invention relates to a reforming catalyst for hydrogen production and a hydrogen production apparatus using the catalyst, and in particular, in hydrogen production in a fuel cell system using a hydrogen source such as hydrocarbon as a raw material, it is inexpensive, durable, and widely used. The present invention relates to a hydrogen production reforming catalyst capable of producing hydrogen under conditions, a hydrogen production apparatus and a fuel cell system using the catalyst.

  In recent years, with increasing environmental awareness, attention has been focused on energy using hydrogen, which has a low environmental impact. As one of the energy technologies using hydrogen, fuel cells that can extract electric energy from the reaction of hydrogen and oxygen without causing the direct emission of carbon dioxide, which is the cause of global warming, and the destruction of the ozone layer, have attracted attention. ing. Various raw materials such as natural gas, liquid fuel, and petroleum-based hydrocarbons have been studied as hydrogen sources for fuel cells. Especially, hydrocarbons represented by city gas, LP gas, naphtha, gasoline, kerosene, The supply infrastructure has been established and is widely distributed in large quantities, so it is considered promising as a hydrogen source. Hydrogen production in fuel cell systems using these hydrocarbons as raw materials is required to be efficiently performed in various states including starting and stopping of the system.

  In order to obtain hydrogen from the hydrocarbons, it is common to perform a steam reforming reaction in the presence of a reforming catalyst for hydrogen production. As the reforming catalyst for hydrogen production, ruthenium, As a prior art, a noble metal catalyst supporting a noble metal such as rhodium and a nickel catalyst supporting nickel are known. In recent years, noble metal catalysts using noble metals such as ruthenium and rhodium have attracted attention as reforming catalysts for hydrocarbons because they can reduce the amount of water vapor used. Examples include those in which ruthenium is supported on alumina (see Non-Patent Document 1), those in which ruthenium is supported on alumina or silica (see Patent Document 1), zirconia and ruthenium on alumina containing an alkaline earth metal aluminate. The thing which carry | supported the component (refer patent document 2) etc. are mentioned. Although these catalysts can suppress carbon deposition, there is a problem that the cost of the catalyst is high because an expensive noble metal is used. Moreover, in the nickel catalyst which carry | supported nickel, the thing which carry | supported metallic nickel on the alumina support | carrier is mentioned as an example (refer patent document 3). Nickel-based catalysts are economically preferable because they are less expensive than precious metal-based catalysts, but they have the disadvantage of easily causing a decrease in activity due to carbon deposition. To suppress carbon deposition, the steam / carbon ratio is increased. There is a problem that a reaction needs to be performed, and energy consumption increases as the steam supply amount increases. Further, when exposed to a steam atmosphere at a high temperature, there is a problem that the activity is lowered due to aggregation of nickel. Further, by utilizing the characteristics of both the noble metal catalyst and the nickel catalyst, at least an upstream catalyst layer in which at least a ruthenium component is supported on an alumina support and a downstream catalyst layer containing nickel are included. A steam reforming method (refer to Patent Document 4) characterized by the above, a so-called stacked catalyst system has been proposed. However, this stacked catalyst system has a problem that carbon deposition tends to proceed at the interface between different catalyst layers on the upstream side and the downstream side, and carbon deposition in the downstream catalyst layer is still large.

In addition, hydrogen production in a fuel cell system that uses hydrocarbons as a raw material is not limited to steady production conditions, and it is required to efficiently produce hydrogen under a wide range of production conditions that accompany system start / stop. . The reforming catalysts for hydrogen production listed above are mainly assumed to be applied to steam reforming reactions, but in the partial oxidation reaction and autothermal reaction in which oxygen coexists, oxidation and aggregation of ruthenium and nickel As the catalyst deteriorates due to hydrogen, hydrogen production is limited to the steam reforming reaction, and it is difficult to efficiently produce hydrogen under a wide range of conditions. In the hydrogen production reaction in which these oxygens coexist, rhodium may be used as a catalyst. Examples include a catalyst for reforming hydrocarbons composed of rhodium, spinel having the chemical formula MgO.xAl ₂ O ₃ and substantially free of alumina crystal structure (see Patent Document 5), and a support containing cerium oxide. An autothermal reforming catalyst (see Patent Document 6) that supports rhodium and defines the atomic ratio of cerium and rhodium has been proposed, but rhodium is an expensive metal, so that hydrogen production can be performed at low cost. Further reduction of rhodium usage is desired.

JP-A 57-4232 Japanese Patent Laid-Open No. 5-220397 Japanese Patent Publication No.53-12917 JP 2001-342004 A JP 2001-276620 A JP 2002-336702 A

  The present invention relates to a reforming catalyst for hydrogen production that solves the above-described problems of the prior art and a hydrogen production apparatus using the catalyst, and in particular, in hydrogen production in a fuel cell system using a hydrogen source such as hydrocarbon as a raw material. Another object of the present invention is to provide a hydrogen production reforming catalyst that is inexpensive, durable, and capable of producing hydrogen under a wide range of conditions, a hydrogen production apparatus and a fuel cell system using the catalyst.

  As a result of intensive investigations in view of the problems of the prior art, the present inventors have made the platinum group metal and nickel contained on the same carrier, the platinum group metal contains rhodium, and rhodium is the carrier surface layer. This suppresses the amount of expensive platinum group metal used, suppresses carbon deposition on the catalyst and nickel aggregation when exposed to steam atmosphere at high temperatures, and coexists with oxygen such as autothermal reaction. In such a state, the inventors have found that hydrogen can be produced efficiently, and have completed the present invention.

  That is, the present invention provides a catalyst comprising an inorganic composite oxide support containing alumina and supporting a rare earth metal oxide and an alkaline earth metal oxide, and nickel and a platinum group metal supported on the support. In the catalyst, nickel and platinum group metal are supported on the same carrier, rhodium is contained as the platinum group metal, and rhodium is measured by electron probe microanalyzer (EPMA) in the carrier diameter direction through the center of the catalyst cross section. The ratio of the characteristic X-ray intensity of rhodium detected in the range of the distance within 10% of the carrier diameter from the outer surface of the carrier to the characteristic X-ray intensity of all the rhodium detected when The first reforming for hydrogen production in which the ratio of the characteristic X-ray intensity of rhodium detected in the range of the distance within 20% of the support diameter from the surface is 95% or more To provide a medium.

  In the first reforming catalyst for hydrogen production, the supported amount of nickel is 1 to 30 parts by mass in terms of nickel atoms with respect to 100 parts by mass of alumina, and the supported amount of rhodium is rhodium atoms with respect to 100 parts by mass of alumina. It is preferable that it is 0.01-3 mass parts in conversion.

  In the first reforming catalyst for hydrogen production, the supported amount of platinum group metal is preferably 0.01 to 3 parts by mass in terms of platinum group metal atom with respect to 100 parts by mass of alumina.

  In the first reforming catalyst for hydrogen production, the supported amount of the rare earth metal oxide is preferably 2 to 30 parts by mass with respect to 100 parts by mass of alumina.

  In the first reforming catalyst for hydrogen production, the supported amount of the alkaline earth metal oxide is preferably 0.1 to 10 parts by mass with respect to 100 parts by mass of alumina.

  In the first reforming catalyst for hydrogen production, the combination of the rare earth element contained in the rare earth metal oxide and the alkaline earth element contained in the alkaline earth metal oxide is strontium and cerium, magnesium and cerium, It is preferably at least one selected from barium and cerium, strontium and lanthanum, and barium and lanthanum.

  The present invention also provides the second reforming catalyst for producing hydrogen, wherein the alkaline earth metal oxide is strontium oxide and the platinum group metals are rhodium and platinum. To do.

  By the way, hydrocarbons that serve as hydrogen sources may contain a small amount of oxygen molecules during the production and transportation process, and in some local and overseas city gases, a small amount of air is used to adjust the amount of heat. There is also a case of mixing. In such a case, the above raw material may contain oxygen molecules of several hundred to several thousand ppm. However, when hydrocarbons containing oxygen molecules are used as raw materials, conventional catalyst systems using ruthenium or nickel are used because oxygen promotes oxidation and aggregation of the active metal in the catalyst as an oxidizing agent under high-temperature hydrogen production conditions. Causes a decrease in the function of the catalyst in the presence of oxygen. Further, when ruthenium forms ruthenium tetroxide (melting point: 40 ° C.) by oxidation, there is a problem that the ruthenium component is volatilized and desorbed from the catalyst.

  According to the second reforming catalyst for producing hydrogen, the above-mentioned problems are hardly caused in the production of hydrogen using hydrocarbons containing oxygen molecules as raw materials, and inexpensive and efficient production of hydrogen becomes possible.

  In the second reforming catalyst for hydrogen production, the supported amount of nickel is 1 to 30 parts by mass in terms of nickel atoms with respect to 100 parts by mass of alumina, and the supported amount of rhodium is rhodium atoms with respect to 100 parts by mass of alumina. It is 0.01-3 mass parts in conversion, and it is preferable that the load of platinum is 0.001-0.3 mass part in platinum atom conversion with respect to 100 mass parts of alumina.

  In the second reforming catalyst for hydrogen production, the supported amount of strontium oxide is preferably 0.1 to 10 parts by mass with respect to 100 parts by mass of alumina.

  In the second reforming catalyst for producing hydrogen, the supported amount of rare earth metal oxide is preferably 2 to 30 parts by mass with respect to 100 parts by mass of alumina.

  The present invention provides a method for producing the first and second reforming catalysts for hydrogen production, wherein the inorganic composite oxide support or its precursor is oxygenated before the rhodium is supported on the inorganic composite oxide support. The manufacturing method of the reforming catalyst for hydrogen production which has the process of baking at the temperature of 650-1200 degreeC in presence of this.

  The present invention provides a hydrogen production method for obtaining hydrogen by reforming a hydrogen raw material containing hydrocarbon compounds with the first or second hydrogen production reforming catalyst according to the present invention.

  In the present invention, a hydrogen raw material containing oxygen molecules and hydrocarbon compounds and having an oxygen molecule content of 5% by volume or less is steam-reformed with the second hydrogen production reforming catalyst according to the present invention. A hydrogen production method for obtaining hydrogen is provided.

  The present invention includes a reforming unit having the first or second reforming catalyst for hydrogen production according to the present invention, and a gas containing at least one selected from oxygen and steam in the reforming unit, A product containing hydrogen from a hydrogen raw material by at least one reaction selected from a partial oxidation reaction, an autothermal reforming reaction and a steam reforming reaction, comprising a supply unit for supplying a hydrogen raw material containing hydrocarbon compounds A hydrogen production apparatus is obtained.

  According to the present invention, in the above hydrogen production apparatus, the reforming unit includes the second reforming catalyst for hydrogen production according to the present invention, and the supply unit includes a gas containing steam and oxygen molecules in the reforming unit. And a hydrogen production apparatus for obtaining a product containing hydrogen from a raw material by a steam reforming reaction, which supplies a hydrogen raw material containing hydrocarbon compounds.

  The present invention provides a fuel cell system comprising the hydrogen production apparatus according to the present invention.

  According to the present invention, a hydrogen production reforming catalyst capable of producing hydrogen under a wide range of conditions and a low cost and high durability in hydrogen production using a hydrogen source such as hydrocarbon as a raw material, and a production method thereof are provided. Can do. Moreover, according to this invention, the hydrogen production method using the reforming catalyst for hydrogen production of this invention, a hydrogen production apparatus, and a fuel cell system can be provided.

  Moreover, according to the reforming catalyst for hydrogen production of the present invention, hydrogen can be efficiently produced even in a state where oxygen coexists, such as autothermal reaction. Furthermore, according to the present invention, a hydrogen production reforming catalyst capable of efficiently producing hydrogen even if it is a hydrogen raw material containing oxygen molecules and hydrocarbon compounds, and a hydrogen production method using the same A hydrogen production apparatus and a fuel cell system can be provided.

It is a graph which shows the characteristic X-ray intensity with respect to the support | carrier radial direction of the catalyst cross section of the rhodium contained in a catalyst, and the photograph of the EPMA measurement of the catalyst A. It is a graph which shows the characteristic X-ray intensity with respect to the support | carrier diameter direction of the catalyst cross section of the rhodium contained in a catalyst, and the photograph of the EPMA measurement of the catalyst B. It is a graph which shows the characteristic X-ray intensity with respect to the support | carrier diameter direction of the catalyst cross section of the rhodium contained in a catalyst, and the photograph of the EPMA measurement of the catalyst C. It is a conceptual diagram which shows an example of the fuel cell system which concerns on embodiment of this invention.

  Hereinafter, the present invention will be described in more detail.

  The reforming catalyst for hydrogen production of this embodiment contains alumina, an inorganic composite oxide carrier supporting rare earth metal oxide and alkaline earth metal oxide, nickel and a platinum group metal supported on the carrier, The catalyst has nickel and a platinum group metal supported on the same carrier, contains rhodium as the platinum group metal, and has a carrier diameter passing through the center of the catalyst cross section by an electron probe microanalyzer (EPMA). The ratio of the characteristic X-ray intensity of rhodium detected within a distance within 10% of the carrier diameter from the outer surface of the carrier to the characteristic X-ray intensity of all rhodium detected when the rhodium line analysis measurement was performed in the direction Is 90% or more and the ratio of the characteristic X-ray intensity of rhodium detected in the range of the distance from the carrier outer surface within 20% of the carrier diameter is 95% or more And features.

  The reforming catalyst for hydrogen production of the present embodiment has nickel and rhodium-containing platinum group metal supported on the same carrier, and further, rhodium is distributed on the surface layer of the carrier at a specific ratio or more, so that expensive rhodium While suppressing the amount of the catalyst used, it is possible to suppress a decrease in the performance of the catalyst when exposed to a steam atmosphere at a high temperature.

  The cause of the effect of suppressing the deterioration in the performance of the catalyst is not clear. However, since nickel and a platinum group metal containing rhodium are present on the same support, (1) each metal atom is composed of other metal atoms. Aggregation is suppressed. (2) Since no boundary surface of each metal atom is generated, a uniform reaction field is provided. (3) Hydrogen molecules activated on the platinum group metal are spilled over adjacent nickel. The reason for this is that it is supplied to suppress carbon deposition on nickel. In addition, since it is easy to donate electrons between metal atoms of each other, (4) rhodium distributed on the support surface layer suppresses oxidation of nickel in the support and suppresses reduction of nickel on the catalyst surface due to formation of nickel aluminate. (5) The action of coexisting nickel suppressing sulfur adhesion to the platinum group metal is also considered as a reason. In the reforming catalyst for hydrogen production of the present embodiment, these functions function in combination, thereby reducing the performance of the catalyst when exposed to a steam atmosphere at a high temperature while suppressing the amount of expensive rhodium used. Presumed to have an inhibitory effect.

  In order to obtain the above-mentioned effects in a composite and efficient manner, the carrier surface layer portion at a distance within 10% of the carrier diameter from the outer surface of the carrier toward the center of the carrier out of the total rhodium content carried on the carrier. It is preferable that 90% by mass or more of rhodium is distributed on the surface of the carrier, and 95% by mass or more of rhodium is distributed on the carrier surface layer within a distance of 20% or less. When the ratio of rhodium contained in the carrier surface layer part within the distance of 10% or less is less than 90% by mass, or the ratio of rhodium contained in the carrier surface layer part within the distance of 20% or less is less than 95% by mass, the carrier The ratio of rhodium present inside the carrier which does not function easily for the catalytic reaction on the surface layer becomes too large, and the above-described effects are hardly obtained, and the amount of expensive rhodium used cannot be suppressed, which is not preferable.

The mass distribution of rhodium contained in the support is the characteristic X-ray intensity of rhodium detected when the rhodium is analyzed by electron probe microanalyzer (EPMA) in the diameter direction of the support passing through the center of the catalyst cross section. It can be obtained from the distribution of. Specifically, the characteristic X-ray intensity (cps) of all rhodium detected when rhodium was analyzed in the diameter direction of the carrier passing through the center of the catalyst cross section is I ₁₀₀ , and the carrier diameter from the outer surface of the carrier is 10 The characteristic X-ray intensity (cps) of rhodium detected within a range of distance within ₁₀ % is I ₁₀ , and the characteristic X-ray intensity (cps) of rhodium detected within a distance within 20% of the carrier diameter from the outer surface of the carrier Is I ₂₀ , the distribution ratio of rhodium supported on the carrier can be calculated by the following formula. Incidentally, R ₁₀ represents a content of rhodium from the outer surface of the support toward the center of the carrier contained in the carrier surface part of the distance of within 10% of the carrier diameter (mass%), R ₂₀ is a carrier The content ratio (% by mass) of rhodium contained in the surface layer of the carrier at a distance within 20% of the carrier diameter from the outer surface toward the center of the carrier.
R ₁₀ = I ₁₀ ÷ I ₁₀₀ × 100
R ₂₀ = I ₂₀ ÷ I ₁₀₀ × 100

  The carrier in the reforming catalyst for hydrogen production of this embodiment is an inorganic composite oxide carrier containing alumina and supporting a rare earth metal oxide and an alkaline earth metal oxide.

Alumina is not particularly limited by composition or structure, and includes α-alumina, γ-alumina, and a mixture of these aluminas and inorganic metal oxides selected from silica, titania, zirconia, and the like. . B. of alumina E. T.A. The specific surface area is not particularly limited, but it may be necessary to disperse the supported nickel and platinum group metals sufficiently. E. T.A. The specific surface area is preferably ³ to 200 m ² / g. B. E. T.A. When the specific surface area is less than 3 m ² / g, nickel and platinum group metals cannot be sufficiently dispersed on the support surface layer, making it difficult to obtain a predetermined catalyst activity and catalyst life. E. T.A. When the specific surface area is larger than 200 m ² / g, the void ratio on the surface is high, and it is difficult to obtain a sufficient carrier strength.

  Examples of the rare earth metal oxide include oxides of one or more rare earth metals selected from lanthanum, cerium, praseodymium, neodymium, promethium, samarium, ytterbium, and the like. The rare earth metal is particularly preferably lanthanum or cerium. These rare earth metal oxides can be obtained by firing using rare earth metal compounds such as chlorides, nitrates and acetates as precursors.

  The supported amount of the rare earth metal oxide is preferably 2 to 30 parts by mass, more preferably 5 to 20 parts by mass, and even more preferably 10 to 18 parts by mass with respect to 100 parts by mass of alumina. preferable. When the loading amount of the rare earth metal oxide is more than 30 parts by mass, it is not preferable because it exists in an excess amount with respect to alumina and an effect of addition relative to the content cannot be obtained. On the other hand, if the supported amount of the rare earth metal oxide is less than 2 parts by mass, the effect of addition becomes low, which is not preferable.

  Examples of the alkaline earth metal oxide include oxides of one or more alkaline earth metals selected from magnesium, calcium, strontium, barium and the like. The alkaline earth metal is particularly preferably magnesium, strontium, or barium. These alkaline earth metal oxides can be obtained by firing with an alkaline earth metal compound such as chloride, nitrate, acetate, etc. as a precursor.

  The supported amount of the alkaline earth metal oxide is preferably 0.1 to 10 parts by weight, more preferably 0.5 to 8 parts by weight, and 1 to 8 parts by weight with respect to 100 parts by weight of alumina. Even more preferably. When the supported amount of the alkaline earth metal oxide is more than 10 parts by mass, it is not preferable because it is present in an excessive amount with respect to alumina and the effect of addition relative to the content cannot be obtained. On the other hand, if the supported amount of the alkaline earth metal oxide is less than 0.1 parts by mass, the effect of addition becomes low, which is not preferable.

  The combination of the rare earth element contained in the rare earth metal oxide and the alkaline earth element contained in the alkaline earth metal oxide in this embodiment is strontium and cerium, magnesium and cerium, barium and cerium, strontium and lanthanum, and barium. And at least one selected from lanthanum. Particularly preferred is a combination of strontium and cerium, or barium and cerium.

  The supported amount of nickel is preferably 1 to 30 parts by mass, more preferably 3 to 25 parts by mass, and further preferably 5 to 20 parts by mass in terms of nickel atoms with respect to 100 parts by mass of alumina. More preferred. When the amount of nickel supported is more than 30 parts by mass, it is not preferable because it is present in an excessive amount with respect to alumina and the effect of addition relative to the content cannot be obtained. On the other hand, if the supported amount of nickel is less than 1 part by mass, the effect of addition becomes low, which is not preferable.

  The reforming catalyst for hydrogen production of this embodiment contains rhodium as a platinum group metal. That is, at least nickel and rhodium are supported on the inorganic composite oxide carrier. The supported amount of rhodium is preferably 0.01 to 3 parts by mass, more preferably 0.05 to 1 part by mass, and more preferably 0.05 to 0. Even more preferably 5 parts by weight. If the supported amount of rhodium is more than 3 parts by mass, the expensive rhodium metal is present in an excessive amount with respect to alumina, and not only the addition effect compared with the content cannot be obtained, but also the catalyst price is high. This is not preferable. On the other hand, if the amount of rhodium supported is less than 0.01 parts by mass, the effect of addition is reduced, which is not preferable.

  In addition to rhodium, the platinum group metal can also contain one or more platinum group metals selected from ruthenium, palladium, platinum and the like. The total supported amount of platinum group metal including rhodium is preferably 0.01 to 3 parts by mass, more preferably 0.05 to 2 parts by mass in terms of platinum group atoms with respect to 100 parts by mass of alumina. Preferably, it is 0.1-1 part by mass. If the total supported amount of platinum group atoms is more than 3 parts by mass, it will be present in excess with respect to alumina, and not only will the effect of addition relative to the content not be obtained, but also the catalyst price will be high. It is not preferable. On the other hand, if the total supported amount of platinum group atoms is less than 0.01 parts by mass, the effect of addition becomes low, which is not preferable.

  In the reforming catalyst for hydrogen production of this embodiment, the alkaline earth metal oxide is preferably strontium oxide, and the platinum group metal is preferably rhodium and platinum (hereinafter, this catalyst is referred to as this embodiment). This may be referred to as the second reforming catalyst for production of hydrogen). According to the second reforming catalyst for producing hydrogen according to the present embodiment, it is possible to produce hydrogen at low cost and efficiently even in hydrogen production using hydrocarbons containing oxygen molecules as raw materials.

  Although the cause of the above effect is not clear, in addition to the actions (1) to (5) described above, the presence of platinum and strontium oxide (6) improves the stability of nickel, thereby It is presumed that the action of improving the activity of nickel in the coexisting atmosphere was obtained.

  In the second hydrogen production reforming catalyst according to this embodiment, the supported amount of nickel is 1 to 30 parts by mass in terms of nickel atoms with respect to 100 parts by mass of alumina, and the supported amount of rhodium is 100 parts by mass of alumina. On the other hand, it is 0.01 to 3 parts by mass in terms of rhodium atoms, and the supported amount of platinum is preferably 0.001 to 0.3 parts by mass in terms of platinum atoms with respect to 100 parts by mass of alumina. In the reforming catalyst for hydrogen production according to the present embodiment, the total supported amount of platinum group atoms is 0.011 to 3.3 parts by mass in terms of platinum group atoms with respect to 100 parts by mass of alumina. Preferably, it is 0.05-2 mass parts, More preferably, it is 0.1-1 mass part.

  When the amount of nickel supported is more than 30 parts by mass, it is not preferable because it is present in an excessive amount with respect to alumina and the effect of addition relative to the content cannot be obtained. On the other hand, if the supported amount of nickel is less than 1 part by mass, the effect of addition becomes low, which is not preferable. If the supported amount of rhodium is more than 3 parts by mass, the expensive rhodium metal is present in an excessive amount with respect to alumina, and not only the addition effect compared with the content cannot be obtained, but also the catalyst price is high. This is not preferable. On the other hand, if the amount of rhodium supported is less than 0.01 parts by mass, the effect of addition is reduced, which is not preferable.

  More preferable ranges of the supported amount of nickel and the supported amount of rhodium are the same as the ranges described above.

  Further, from the viewpoint of suppressing the amount of expensive noble metal used and making it an inexpensive catalyst, the supported amount of platinum is 0.005 to 0.2 parts by mass in terms of platinum atoms with respect to 100 parts by mass of alumina. Is more preferable, and it is still more preferable that it is 0.01-0.1 mass part. The molar ratio of platinum to rhodium (Pt / Rh) is preferably 0.05 to 0.5 mol / mol. By supporting platinum so that the molar ratio is in such a range, the amount of the precious metal to be introduced can be suppressed.

  In the second hydrogen production reforming catalyst, the supported amount of strontium oxide is preferably 0.1 to 10 parts by mass, more preferably 0.5 to 8 parts by mass with respect to 100 parts by mass of alumina. Preferably, it is 1-8 mass parts, and it is still more preferable. When the supported amount of strontium oxide is more than 10 parts by mass, it is not preferable because it is present in an excessive amount with respect to alumina and an effect of addition relative to the content cannot be obtained. On the other hand, if the supported amount of strontium oxide is less than 0.1 parts by mass, the effect of addition becomes low, which is not preferable.

  In the second reforming catalyst for hydrogen production, the supported amount of rare earth metal oxide is preferably 2 to 30 parts by mass, more preferably 5 to 20 parts by mass with respect to 100 parts by mass of alumina, It is still more preferable that it is 10-18 mass parts. When the loading amount of the rare earth metal oxide is more than 30 parts by mass, it is not preferable because it exists in an excess amount with respect to alumina and an effect of addition relative to the content cannot be obtained. On the other hand, if the supported amount of the rare earth metal oxide is less than 2 parts by mass, the effect of addition becomes low, which is not preferable.

  In the reforming catalyst for hydrogen production according to the present embodiment, the method for supporting nickel, platinum group metal, rare earth metal oxide and alkaline earth metal oxide on the support is not particularly limited, and is a normal impregnation method or pore fill. Known methods such as the method can be used. Usually, it is dissolved in a solvent containing water or an organic substance as a metal salt or metal complex, and then impregnated on a carrier containing alumina. As the metal salt or metal complex to be contained, chloride, nitrate, sulfate, acetate, acetoacetate and the like can be used. There is no restriction | limiting in particular regarding the frequency | count of an impregnation, or a process, It can be made to divide once or several times. Nickel and rhodium are preferably dissolved in the same solvent and then simultaneously contained in the catalyst. In the case of the second reforming catalyst for producing hydrogen, nickel, rhodium and platinum are preferably dissolved in the same solvent and then simultaneously contained in the catalyst.

  The drying treatment after the inclusion of each metal is not particularly limited with respect to the conditions, but for example, it may be performed in air at 100 ° C. or higher.

  In order for the reforming catalyst for hydrogen production of this embodiment to have a predetermined X-ray intensity distribution in the above-mentioned rhodium line analysis measurement by EPMA, before introducing rhodium into the catalyst, specifically, rhodium is supported on the support. A method of previously calcining an inorganic composite oxide carrier containing alumina and carrying a rare earth metal oxide and an alkaline earth metal oxide or a precursor thereof in the presence of oxygen at a temperature of 650 to 1200 ° C. Is mentioned. The firing temperature is preferably 700 ° C. or higher, more preferably 750 ° C. or higher, preferably 1000 ° C. or lower, and more preferably 900 ° C. or lower.

  As a precursor of the inorganic composite oxide carrier, for example, a carrier containing alumina impregnated with the rare earth metal compound is fired at 400 to 800 ° C. in the presence of oxygen, and this is impregnated with the alkaline earth metal compound. And a carrier containing alumina impregnated with the rare earth metal compound and the alkaline earth metal compound.

  By performing the above-mentioned calcination treatment, rhodium introduced into the catalyst later is easily distributed on the surface of the support with respect to the diameter direction of the inorganic composite oxide support, and the sintering of the inorganic composite oxide support is triggered. The decrease in the catalyst performance due to the aggregation of rhodium can be suppressed. At a temperature lower than 650 ° C., not only rhodium is likely to be distributed in the internal direction of the inorganic composite oxide support after rhodium is introduced, but also thermal aggregation of alumina contained in the inorganic composite oxide support is likely to proceed, It is not preferable because it tends to cause aggregation of rhodium. On the other hand, when the baking treatment is performed at a temperature higher than 1200 ° C., the BET specific surface area of the inorganic composite oxide carrier is decreased, which is not preferable.

  After the introduction of rhodium, the introduced rhodium is distributed and immobilized on the surface of the inorganic composite oxide support by drying or firing at a temperature lower than the firing temperature of the inorganic composite oxide support or precursor described above. Is done. When rhodium is introduced and dried or calcined at a temperature higher than the firing temperature of the inorganic composite oxide support, rhodium distributed on the surface of the inorganic composite oxide support is triggered by sintering of the inorganic composite oxide support. Aggregation progresses and catalyst performance decreases, which is not preferable. The drying or firing temperature after the introduction of rhodium can be set based on the firing temperature of the inorganic composite oxide carrier or the precursor thereof, but is preferably in the range of 100 ° C. or more and less than 650 ° C., more preferably It is the range of 130-600 degreeC. A temperature lower than 100 ° C. is not preferable because rhodium introduced due to insufficient moisture desorption is not immobilized on the surface of the inorganic composite oxide carrier.

  The reforming catalyst for hydrogen production according to the present embodiment can be subjected to reduction treatment or metal immobilization treatment as necessary. The treatment method is not particularly limited, and for example, gas phase reduction treatment or liquid phase reduction treatment under hydrogen flow can be performed.

  The method for producing a reforming catalyst for hydrogen production according to the present embodiment is not particularly limited as long as the above-described conditions are satisfied. For example, a predetermined amount of rare earth metal oxide and alkaline earth metal with respect to alumina. After an oxide is introduced to form an inorganic composite oxide support, a platinum group containing nickel and rhodium is added to the fired inorganic composite oxide support after firing at 650 to 1200 ° C. in an air atmosphere. The method of introduce | transducing a metal and then performing a drying or baking process is mentioned.

  There is no restriction | limiting in particular about the form of the reforming catalyst for hydrogen production which concerns on this embodiment, For example, the shape of the support | carrier containing an alumina can be utilized as it is. Alternatively, it can be used as a catalyst formed by tableting and pulverized and sized within a predetermined range, a powder or a catalyst formed into a spherical shape, ring shape, tablet shape, cylindrical shape or the like.

  Next, the hydrogen production method according to this embodiment will be described. The hydrogen production method of this embodiment is a method for obtaining hydrogen by reforming a hydrogen raw material containing hydrocarbon compounds with the above-described reforming catalyst for hydrogen production of this embodiment.

  Specifically, for example, in the presence of the reforming catalyst for hydrogen production described above, a gas containing at least one selected from oxygen and steam and a hydrogen raw material containing hydrocarbon compounds are supplied, Examples thereof include a method of obtaining a product containing hydrogen from a hydrogen raw material by at least one hydrogen production reaction selected from a partial oxidation reaction, an autothermal reforming reaction and a steam reforming reaction.

  Examples of the reaction format using the reforming catalyst for hydrogen production include a fixed bed type, a moving bed type, and a fluidized bed type, and are not particularly limited. Also, the reactor using the reforming catalyst for hydrogen production is not particularly limited.

  Hydrocarbon compounds as raw materials in the hydrogen production reaction contain an organic compound having 1 to 40 carbon atoms, preferably 1 to 30 carbon atoms, more preferably 1 to 6 carbon atoms. Specific examples include saturated aliphatic hydrocarbons, unsaturated aliphatic hydrocarbons, aromatic hydrocarbons, and the like, and saturated aliphatic hydrocarbons and unsaturated aliphatic hydrocarbons are linear or cyclic. Any shape can be used. Such hydrocarbon compounds can contain substituents. As the substituent, either a chain or a ring can be used, and examples thereof include an alkyl group, a cycloalkyl group, an aryl group, an alkylaryl group, and an aralkyl group. These hydrocarbon compounds may be substituted with a substituent containing a hetero atom such as a hydroxy group, an alkoxy group, a hydroxycarbonyl group, an alkoxycarbonyl group, or a formyl group.

  Specific examples of the hydrocarbon compounds include chain saturated aliphatic hydrocarbons such as methane, ethane, propane, butane, pentane, hexane, heptane, and octane and their structural isomers, ethylene, propylene, butene, pentene, hexene. Chain unsaturated aliphatic hydrocarbons such as heptene and octene and their structural isomers, cyclic hydrocarbons such as cyclopentane, cyclohexane, cycloheptane and cyclooctane and their structural isomers, benzene, toluene, xylene, naphthalene, And aromatic hydrocarbons such as biphenyl. Moreover, the material which contains these as a single item or a mixture can be used. Examples thereof include city gas, natural gas, LPG, naphtha, gasoline, kerosene, and light oil.

  In addition, as hydrocarbon compounds having a substituent containing a hetero atom, raw materials containing alcohols, ethers, biofuels and the like can be used. Examples of the alcohols include methanol and ethanol. Examples of the ethers include dimethyl ether. Examples of the biofuel include biogas, bioethanol, biodiesel, and biojet. And so on.

  In addition, a raw material containing hydrogen, water, carbon dioxide, carbon monoxide, oxygen, nitrogen or the like as the above raw material can also be used. For example, when hydrodesulfurization is performed as a pretreatment of the raw material, the hydrogen residue used in the reaction can be used as it is without being particularly separated.

  The sulfur concentration contained in the hydrocarbon compound used as a raw material is preferably 50 mass ppb or less, more preferably 20 mass ppb or less, and still more preferably 10 mass ppb or less as the mass of sulfur atoms. If the sulfur concentration exceeds 50 mass ppb, poisoning of the reforming catalyst with sulfur proceeds and carbon deposition is promoted, which is not preferable. If necessary, it is preferable to desulfurize the raw material to reduce the sulfur concentration as a pretreatment for the hydrogen production reaction. There are no particular limitations on the raw material desulfurization method, and one or more known techniques such as hydrodesulfurization and adsorption separation, which are generally used industrially, can be used. For example, a method of performing hydrodesulfurization treatment in the presence of a predetermined desulfurization catalyst and hydrogen and removing the produced hydrogen sulfide with an absorbent can be exemplified. There is no restriction | limiting in particular also in the implementation method of a desulfurization process, For example, you may implement just before hydrogen production reaction, and you may use the raw material which processed beforehand by the independent desulfurization process.

  In the present embodiment, a hydrogen raw material containing oxygen molecules and hydrocarbon compounds can be used. In this case, it is preferable to perform a steam reforming reaction using the second reforming catalyst for hydrogen production according to the present embodiment. The content of oxygen molecules in the hydrogen raw material is preferably 5% by volume or less in terms of gas, more preferably 2% by volume or less, and even more preferably 1% by volume or less. These concentrations are preferably satisfied at the inlet of the reforming section having the second hydrogen production reforming catalyst according to the present embodiment. When the oxygen source contained in the hydrogen raw material containing hydrocarbon compounds is more than 5% by volume, the effect of the present invention can be obtained even in the steam reforming reaction. In this case, the hydrocarbon as the raw material This is not preferable from the viewpoint of ensuring the stability and safety of the raw materials, as well as the compound being prone to auto-oxidation and reducing the production efficiency of hydrogen.

In this embodiment, the space velocity of the flow material introduced into the reforming catalyst for hydrogen production is preferably a gas space velocity (hereinafter referred to as GHSV), preferably 10 to 10,000 h ⁻¹ , more preferably 50 to 5, 000h ^-1, more preferably in the range of 100~3,000h ^-1. If the GHSV is higher than 10,000 h ^−1, the contact time between the raw material and the catalyst cannot be secured sufficiently, and the reaction conversion does not proceed, which is not preferable. On the other hand, if GHSV is lower than 10 h ^−1, it is not preferable because the amount of hydrogen production relative to the amount of catalyst is small and the hydrogen production efficiency is low. The liquid space velocity (hereinafter referred to as LHSV) is preferably 0.05 to 5.0 h ⁻¹ , more preferably 0.1 to 2.0 h ⁻¹ , and still more preferably 0.2 to 1.0 h ⁻¹ . It is a range. When LHSV is higher than 5.0 h ^−1, the contact time between the raw material and the catalyst cannot be ensured sufficiently, so that the reaction conversion does not proceed and it is not preferable. On the other hand, if LHSV is lower than 0.05 h ^−1, it is not preferable because the amount of hydrogen production relative to the amount of catalyst is small and the hydrogen production efficiency is low.

  The reaction temperature of the hydrogen production method of the present embodiment is not particularly limited, but is preferably 200 to 1000 ° C, more preferably 250 to 900 ° C, and further preferably 300 to 800 ° C. When the temperature is higher than 1000 ° C., the aggregation of the metal contained in the catalyst is likely to proceed, and the early performance deterioration of the catalyst is accompanied. On the other hand, a temperature lower than 200 ° C. is not preferable because a reaction rate sufficient for hydrogen production cannot be obtained.

  The reaction pressure of the hydrogen production method of the present embodiment is not particularly limited, but is preferably atmospheric pressure to 20 MPa, more preferably atmospheric pressure to 5 MPa, and further preferably atmospheric pressure to 1 MPa. Although it is possible to carry out at a pressure lower than the atmospheric pressure or a pressure higher than 20 MPa, in that case, it is necessary for the production equipment to cope with reduced pressure and high pressure, which is not economically preferable.

  In the present embodiment, when performing the steam reforming reaction, the amount of steam introduced into the steam reforming reaction is the ratio of the number of moles of water molecules to the number of moles of carbon atoms contained in the raw material hydrocarbon compounds (steam / carbon ratio: (Hereinafter referred to as S / C) is preferably set to be in the range of 0.3 to 10, more preferably 0.5 to 5, and further preferably 1.5 to 3.5. When S / C is less than 0.3, the steam required for the steam reforming reaction is insufficient, and coke deposition is promoted, so that the performance degradation of the catalyst is remarkably accelerated. On the other hand, when S / C is larger than 10, the energy required for steam supply and the cost required for generating / collecting surplus steam increase, which is not preferable.

Further, in the present embodiment, by using the hydrogen production reforming catalyst according to the present embodiment, hydrogen can be efficiently produced even in a state where oxygen coexists, such as a partial oxidation reaction and an autothermal reaction. The amount of oxygen introduced into these reactions is preferably a ratio of the number of moles of oxygen molecules to the number of moles of carbon atoms contained in the raw material hydrocarbon compounds (oxygen / carbon ratio: hereinafter referred to as O ₂ / C), preferably 0. It is 8 or less, more preferably 0.5 or less, and still more preferably 0.3 or less. A case where O ₂ / C is larger than 0.8 is not preferable because the generation reaction of carbon dioxide and water proceeds and the generation amount of hydrogen decreases.

  According to the hydrogen production method of this embodiment, hydrogen is a main component from hydrocarbon fuels such as city gas, natural gas, LPG, naphtha, and kerosene by a hydrogen production reaction by the reforming catalyst for hydrogen production according to this embodiment. The reformed gas contained as can be obtained. Moreover, the mixed gas containing hydrogen obtained by the hydrogen production reaction can be used as a fuel for a fuel cell as it is in the case of a solid oxide fuel cell. In addition, when carbon monoxide needs to be removed, such as phosphoric acid fuel cells and polymer electrolyte fuel cells, it can be suitably used as a fuel for fuel cells by using a carbon monoxide removal step in combination. Can do.

  Next, a hydrogen production apparatus and a fuel cell system according to this embodiment will be described.

  The hydrogen production apparatus of the present embodiment includes a reforming unit having the above-described reforming catalyst for hydrogen production according to the present embodiment, and a gas containing at least one selected from oxygen and steam in the reforming unit. , Comprising a supply unit for supplying a hydrogen raw material containing hydrocarbon compounds, and containing hydrogen from the hydrogen raw material by at least one reaction selected from a partial oxidation reaction, an autothermal reforming reaction and a steam reforming reaction To get things.

  In the hydrogen production apparatus of the present embodiment, the reforming section has the second hydrogen production reforming catalyst of the present embodiment, the supply section includes a gas containing steam in the reforming section, oxygen molecules, and hydrocarbon compounds. And a hydrogen raw material containing hydrogen, and a product containing hydrogen can be obtained from the raw material by a steam reforming reaction.

  The fuel cell system according to the present embodiment includes the hydrogen production apparatus and the fuel cell stack, and includes, for example, the configuration of FIG. FIG. 1 is a schematic view showing an example of the fuel cell system of the present embodiment.

  In FIG. 1, the fuel in the fuel tank 3 flows into the desulfurizer 5 through the fuel pump 4. The desulfurizer 5 can be filled with, for example, a copper-zinc-based or nickel-zinc-based sorbent. At this time, if necessary, a hydrogen-containing gas from at least one of the downstream of the reformer 7, the downstream of the shift reactor 9, the downstream of the carbon monoxide selective oxidation reactor 10, and the anode off-gas can be added. The fuel desulfurized in the desulfurizer 5 is mixed with water from the water tank 1 through the water pump 2, introduced into the vaporizer 6, vaporized, and sent to the reformer 7.

  The catalyst of the present embodiment is used as the catalyst of the reformer 7 and is filled in the reformer 7. The reformer reaction tube is heated by a burner 18 using fuel from the fuel tank 3 (hydrogen raw material containing hydrocarbon compounds) and anode off-gas as fuel, preferably 200 to 1000 ° C., more preferably 300 to 900. ° C, more preferably in the range of 400-800 ° C.

  In the present embodiment, the supply unit 20 includes a water tank 1, a water pump 2, a fuel tank 3, and a desulfurizer 5, and the reforming unit 7 includes at least one selected from oxygen and steam. Any other configuration may be used as long as it supplies a gas and a hydrogen raw material containing hydrocarbon compounds.

  The reformed gas containing hydrogen and carbon monoxide produced in this way is passed through the shift reactor 9 and the carbon monoxide selective oxidation reactor 10 in order so as not to affect the characteristics of the fuel cell. The carbon monoxide concentration is reduced. Examples of the catalyst used in these reactors include an iron-chromium catalyst and / or a copper-zinc catalyst for the shift reactor 9, and a ruthenium catalyst for the carbon monoxide selective oxidation reactor 10. it can.

  According to the above-described steam reforming catalyst, hydrogen production apparatus, and fuel cell system, hydrogen production using a hydrogen source such as hydrocarbon as a raw material is inexpensive, highly durable, and efficiently produces hydrogen under a wide range of conditions. Is possible.

  The effects of the present invention will be described more specifically with reference to the following examples, but the present invention is not limited to the following examples. The “external ratio with respect to alumina” of each supported component means the mass ratio of each component when the mass of alumina is 100 mass%, and the mass% of each component indicated by this external ratio is 100% alumina. It can be paraphrased with the mass part with respect to the mass part.

[Preparation of catalyst]
<Example 1 (Catalyst A)>
Pore volume 0.43 ml / g, B.I. E. T.A. The γ-alumina support formed into a spherical shape of ² to 3 mmφ with a specific surface area of 182 m ² / g was dried at 150 ° C. for 6 hours, then impregnated with an aqueous solution containing cerium nitrate, dried at 150 ° C. for 8 hours, and then 400 Air calcination was performed at 5 ° C for 5 hours. This was impregnated with an aqueous solution containing barium nitrate, dried at 150 ° C. for 8 hours, and then calcined at 800 ° C. for 5 hours in an air atmosphere, so that the supported amount of cerium oxide was 16% with respect to alumina. An oxide-supported carrier A having a mass% and a supported amount of barium oxide of 7 mass% was obtained.

  Next, the obtained oxide-supported carrier A was impregnated with an aqueous solution containing nickel nitrate and rhodium nitrate, dried at 150 ° C. for 8 hours, and then calcined at 600 ° C. for 5 hours. As a result, a catalyst having an external ratio with respect to alumina, a nickel carrying amount of 13% by mass, a rhodium carrying amount of 0.25% by mass, a cerium oxide carrying amount of 16% by mass, and a barium oxide carrying amount of 7% by mass. Got. This was designated as “catalyst A”. FIG. 1 shows a photograph of EPMA measurement of this catalyst A and a graph showing the characteristic X-ray intensity with respect to the carrier diameter direction of the catalyst cross section of rhodium contained in the catalyst. In the graph of FIG. 1, 0.5 on the horizontal axis (in the carrier diameter direction) is the center of the diameter, and 0.0 and 1.0 indicate the outer surface of the carrier. The vertical axis (Rh detection intensity) indicates the proportion of rhodium distribution in the carrier diameter direction.

  EPMA measurement is a sample in which the catalyst to be measured is resin-embedded, and the measurement surface is polished and then subjected to carbon vapor deposition, using an electron probe microanalyzer (Electron Beam Analyzer JXA-8900R manufactured by JEOL Ltd.) The analysis was performed under linear analysis conditions of an acceleration voltage of 20 kV, a probe current of 0.1 μA, a beam diameter of 10 μmφ, and a step width of 10 μm.

<Example 2 (Catalyst B)>
In the same manner as in Example 1 except that strontium nitrate was used instead of barium nitrate in Example 1, the supported amount of cerium oxide was 16% by mass with respect to alumina, and the supported amount of strontium oxide was An oxide-supporting carrier B having 4% by mass was obtained.

  Next, nickel and rhodium were introduced into the obtained oxide-carrying support B in the same procedure as in Example 1, and the nickel-carrying amount was 13% by mass and the rhodium-carrying amount at an external ratio with respect to alumina. Was 0.25% by mass, the supported amount of cerium oxide was 16% by mass, and the supported amount of strontium oxide was 4% by mass. This was designated as “catalyst B”. FIG. 2 shows a photograph of EPMA measurement of this catalyst B and a graph showing the characteristic X-ray intensity with respect to the carrier diameter direction of the catalyst cross section of rhodium contained in the catalyst.

<Example 3 (Catalyst C)>
In Example 2, an oxide-supported carrier C was obtained in the same manner as in Example 2 except that the supported amount of strontium oxide was 7% by mass.

  Next, the obtained oxide-supported carrier C was impregnated with an aqueous solution containing nickel nitrate, rhodium nitrate and chloroplatinic acid, dried at 150 ° C. for 8 hours, and then calcined at 600 ° C. for 5 hours. As a result, the nickel loading was 13% by mass with respect to alumina, the rhodium loading was 0.25% by mass, the platinum loading was 0.06% by mass, the cerium oxide loading was 16% by mass, oxidation. A catalyst having a strontium loading of 7% by mass was obtained. This was designated as “Catalyst C”. FIG. 3 shows a photograph of EPMA measurement of the catalyst C and a graph showing the characteristic X-ray intensity with respect to the carrier diameter direction of the catalyst cross section of rhodium contained in the catalyst.

<Example 4 (Catalyst D)>
In the same manner except that magnesium nitrate was used instead of barium nitrate in Example 1, the supported amount of cerium oxide was 12% by mass with respect to alumina, the supported amount of magnesium oxide was 7% by mass, A catalyst having a nickel loading of 13% by mass and a rhodium loading of 0.25% by mass was obtained. This was designated as “Catalyst D”. The result of EPMA measurement showed the same tendency as in Example 1.

<Example 5 (Catalyst E)>
In the same manner except that lanthanum nitrate was used instead of cerium nitrate in Example 1, the supported amount of lanthanum oxide was 16% by mass with respect to alumina, the supported amount of barium oxide was 4% by mass, A catalyst having a nickel loading of 8% by mass and a rhodium loading of 0.25% by mass was obtained. This was designated as “catalyst E”. The result of EPMA measurement showed the same tendency as in Example 1.

<Example 6 (Catalyst F)>
In the same manner except that lanthanum nitrate was used instead of cerium nitrate in Example 2, the supported amount of lanthanum oxide was 12% by mass with respect to alumina, the supported amount of strontium oxide was 8% by mass, A catalyst having a nickel loading of 15% by mass and a rhodium loading of 0.20% by mass was obtained. This was designated as “catalyst F”. The results of EPMA measurement showed the same tendency as in Example 2.

[Evaluation of rhodium distribution]
Content ratio (mass%) of rhodium contained in the surface portion of the carrier at a distance within 10% of the carrier diameter from the outer surface of the carrier toward the center of the carrier (denoted as “Rh content within 10% of the surface layer” in the table) ) R ₁₀ and the content (ratio by mass) of rhodium contained in the carrier surface layer at a distance within 20% of the carrier diameter from the outer surface of the carrier toward the center of the carrier (in the table, “within 20% of the surface layer R ₂₀ was calculated according to the following formula.
R ₁₀ = I ₁₀ ÷ I ₁₀₀ × 100
R ₂₀ = I ₂₀ ÷ I ₁₀₀ × 100
In the above formula, I ₁₀₀ represents the characteristic X-ray intensity (cps) of the total rhodium detected, and I ₁₀ is the characteristic X of the rhodium detected within a range within 10% of the carrier diameter from the outer surface of the carrier. The line intensity (cps) is indicated, and I ₂₀ indicates the characteristic X-ray intensity (cps) of rhodium detected in the range of a distance within 20% of the carrier diameter from the outer surface of the carrier.

  The content of rhodium contained in the range of 10% and 20% of the surface layer of the support of catalysts A to F with respect to the total rhodium content contained in the catalyst, determined from the X-ray intensity distribution of the EPMA measurement of each catalyst. Table 1 shows. It can be seen that in each of the catalysts A to F, 90% by mass or more of the total rhodium content is distributed within the range of 10% or less of the surface layer of the support, and 95% or more is distributed within the range of 20% of the surface layer. .

<Comparative Example 1 (Catalyst G)>
The oxide-supported carrier A in Example 1 was impregnated with an aqueous solution containing rhodium nitrate, dried at 150 ° C. for 8 hours, and then calcined at 600 ° C. for 5 hours. As a result, a catalyst having an external ratio with respect to alumina, a rhodium carrying amount of 0.5% by mass, a cerium oxide carrying amount of 16% by mass, and a barium oxide carrying amount of 7% by mass was obtained. This was designated “catalyst G”.

<Comparative Example 2 (Catalyst H)>
The oxide-supported carrier A in Example 1 was impregnated with an aqueous solution containing nickel nitrate, dried at 150 ° C. for 8 hours, and then calcined at 600 ° C. for 5 hours. As a result, a catalyst having an external ratio with respect to alumina and having a nickel loading of 26 mass%, a cerium oxide loading of 16 mass%, and a barium oxide loading of 7 mass% was obtained. This was designated as “Catalyst H”.

<Comparative Example 3 (Catalyst I)>
50 ml each of Catalyst D and Catalyst E obtained in Comparative Example 1 and Comparative Example 2 were mixed in equal amounts. As a result, it is an external ratio with respect to alumina, a nickel carrying amount of 13% by mass, a rhodium carrying amount of 0.25% by mass, a cerium oxide carrying amount of 16% by mass, and a barium oxide carrying amount of 7% by mass. A catalyst was obtained. This was designated as “catalyst I”.

[Catalyst evaluation by steam reforming reaction (Evaluation J)]
The catalyst was evaluated in a steam reforming reaction using a fixed bed microreactor. 1 cc of a catalyst is packed in a reaction tube (inner diameter of about 9 mm), and this is installed in a tubular electric furnace. At a pressure of 450 ° C. and a steam / carbon ratio (molar ratio) of 2.7 at atmospheric pressure, propane Gas was introduced as a raw material at GHSV 5,000 h- ¹ . This was designated as “Evaluation J”.

  The reaction product gas is analyzed for its composition using a gas chromatogram, and the propane conversion rate obtained by the following formula (1) is calculated based on the number of moles of the carbon component contained in the reaction product gas. Conversion was determined. This was designated as “initial conversion rate”.

In the formula (1), “C1 compound” is a general term for compounds having 1 carbon atom, and specifically means CO, CO ₂ , and CH ₄ .

  Propane conversion (%) = (number of moles of C1 compound contained in reaction product gas) / (total number of moles of carbon atoms contained in reaction product gas) × 100 (1)

  After this, steam was passed through the catalyst filled in the reaction tube at 800 ° C. for 4 hours to perform heat deterioration treatment, and then propane gas was introduced under the same conditions as described above. Asked. This was designated as “post-deterioration conversion”. These results are shown in Table 1.

[Evaluation of catalyst by autothermal reforming reaction (Evaluation K)]
Evaluation was performed by autothermal reforming reaction using the microreactor used in Evaluation G. 1 cc of a catalyst is packed in a reaction tube (inner diameter of about 9 mm), and this is installed in a tubular electric furnace. At atmospheric pressure, the reaction temperature is 400 ° C., the steam / carbon ratio (molar ratio) is 2.7, the oxygen / carbon ratio is (Molar ratio) Under the condition of 0.3, propane gas was introduced as a raw material at GHSV 1,500 h ⁻¹ . This was designated as “Evaluation K”. After obtaining the initial conversion rate in the same manner as in Evaluation G, the steam was passed through the catalyst filled in the reaction tube at 800 ° C. for 4 hours to perform heat deterioration treatment, and then propane gas was introduced under the same conditions as above. Similarly, the post-deterioration conversion was determined. These results are shown in Table 1.

  Catalysts A to F are catalysts in which the platinum group contains rhodium and nickel and the platinum group metal are contained in the same carrier, but the steam reforming reaction of evaluation J and the auto of evaluation K in which oxygen coexists. In the thermal reaction, the post-degradation conversion after flowing the steam for 4 hours at 800 ° C. showed a higher value than the catalysts G to I in which nickel and the platinum group metal are not contained in the same carrier. . From these results, the reforming catalyst for hydrogen production provided by the present invention can efficiently produce hydrogen even in the presence of oxygen such as autothermal reaction in addition to the steam reforming reaction. It can be seen that hydrogen can be efficiently produced under a wide range of conditions.

  Catalysts A to F all showed a higher post-degradation conversion rate than catalyst G, although the rhodium content was less than half that of catalyst G. From these results, the reforming catalyst for hydrogen production provided by the present invention can ensure high durability even in a state where the amount of expensive rhodium used is lower than the catalyst G of Comparative Example 1, It can be seen that hydrogen can be produced at low cost and high durability.

  From the above examples, the hydrogen production reforming catalyst of the present invention enables efficient production of hydrogen under a wide range of conditions at low cost and high durability in hydrogen production in a fuel cell system using hydrocarbon as a raw material. Indicates that

<Example 7 (Catalyst C)>
Catalyst C was obtained in the same manner as in Example 3.

<Example 8 (Catalyst L)>
In the same manner as in Example 3 except that lanthanum nitrate was used instead of cerium nitrate in Example 3 and the supported amount of strontium oxide was 4% by mass, lanthanum oxide was supported at an external ratio with respect to alumina. An oxide-supported carrier L having an amount of 16% by mass and an amount of strontium oxide supported of 4% by mass was obtained.

  Next, with respect to the obtained oxide-supported carrier L, the nickel-supported amount was 8% by mass, the rhodium-supported amount was 0.25% by mass with respect to alumina in the same procedure as in Example 3. A catalyst having a platinum loading of 0.03% by mass, a lanthanum oxide loading of 16% by mass, and a strontium oxide loading of 4% by mass was obtained. This was designated as “catalyst L”. The results of EPMA measurement showed the same tendency as in Example 3.

<Example 9 (Catalyst M)>
In Example 3, an oxide-supported carrier M was obtained in the same manner as in Example 3 except that the supported amount of strontium oxide was 8% by mass.

  Next, with respect to the obtained oxide-supported carrier M, in the same procedure as in Example 3, with an external ratio to alumina, the nickel-supported amount was 15% by mass, the rhodium-supported amount was 0.2% by mass, A catalyst having a platinum loading of 0.1 mass%, a cerium oxide loading of 12 mass%, and a strontium oxide loading of 8 mass% was obtained. This was designated as “catalyst M”. The results of EPMA measurement showed the same tendency as in Example 3.

  Content of rhodium contained in the surface layer of 10% and 20% of the support of catalysts C, L and M, obtained from the distribution of X-ray intensity of EPMA measurement of each catalyst, with respect to the total rhodium content contained in the catalyst The rates are shown in Table 2. Catalysts C, L, and M all have a total rhodium content of 90% by mass or more distributed within the surface layer within 10% of the carrier and 95% by mass or more distributed within the surface layer of 20%. I understand.

<Comparative Example 4 (Catalyst N)>
The oxide-supported carrier C in Example 3 was impregnated with an aqueous solution containing rhodium nitrate, dried at 150 ° C. for 8 hours, and then calcined at 600 ° C. for 5 hours. As a result, a catalyst having an external ratio of 0.5% by mass to rhodium, 16% by mass of cerium oxide, and 7% by mass of strontium oxide was obtained. This was designated as “catalyst N”.

<Comparative Example 5 (Catalyst O)>
The oxide-supported carrier C in Example 3 was impregnated with an aqueous solution containing nickel nitrate and chloroplatinic acid, dried at 150 ° C. for 8 hours, and then air calcined at 600 ° C. for 5 hours. As a result, a catalyst having an external ratio with respect to alumina, a nickel carrying amount of 26% by mass, a platinum carrying amount of 0.1% by mass, a cerium oxide carrying amount of 16% by mass, and a strontium oxide carrying amount of 7% by mass. Got. This was designated as “catalyst O”.

<Comparative Example 6 (Catalyst P)>
The catalyst N and the catalyst O obtained in Comparative Example 4 and Comparative Example 5 were mixed in an equal amount of 50 ml each. As a result, the nickel loading was 13% by mass, the rhodium loading was 0.25% by mass, the platinum loading was 0.05% by mass, the cerium oxide loading was 16% by mass, and the oxidation rate with respect to alumina. 100 ml of a mixed catalyst having a strontium loading of 7% by mass was obtained. This was designated as “catalyst P”.

[Evaluation of catalyst by steam reforming reaction of source gas containing oxygen atom 1 (Evaluation Q)]
The catalyst was evaluated in a steam reforming reaction using a fixed bed microreactor. 1 cc of a catalyst is packed into a reaction tube (inner diameter of about 9 mm), and this is installed in a tubular electric furnace, and propane is used under the conditions of atmospheric pressure, reaction temperature 450 ° C., steam / carbon ratio (molar ratio) 2.5. A gas in which 10% by volume of air (2.0% by volume of oxygen molecules) was mixed with gas was introduced as a raw material at GHSV 10,000h- ¹ . This was designated as “Evaluation Q”.

  The reaction product gas is analyzed for its composition using a gas chromatogram, and the propane conversion rate obtained by the following formula (2) is calculated based on the number of moles of the carbon component contained in the reaction product gas. Conversion was determined. This was designated as “initial conversion rate”.

In the formula (2), “C1 compound” is a general term for compounds having 1 carbon atom, and specifically means CO, CO ₂ , and CH ₄ .

  Propane conversion (%) = (number of moles of C1 compound contained in reaction product gas) ÷ (total number of moles of carbon atoms contained in reaction product gas) × 100 (2)

  After the same raw material was continuously flown for 336 hours, the propane conversion was similarly determined while maintaining the reaction temperature at 450 ° C. This was designated as “post-deterioration conversion”.

[Catalyst Evaluation 2 by Steam Reforming Reaction of Source Gas Containing Oxygen Atoms (Evaluation R)]
In the above evaluation Q, “initial conversion rate” and “post-degradation conversion rate” under the same conditions except that a gas obtained by mixing propane gas with 2.0% by volume of air (0.4% by volume of oxygen molecules) was used as a raw material. Asked.

  These results are shown in Table 2.

  Catalysts C, L, and M all contain rhodium and platinum as platinum group metals, and nickel and platinum group metals are contained in the same carrier, but in evaluation Q and evaluation R, nickel and platinum group metals However, the initial conversion rate and the post-degradation conversion rate were higher than those of the catalysts N to P which were not contained in the same support, and a remarkable difference was confirmed particularly in the evaluation Q having a high content of oxygen molecules. From these results, it is shown that the reforming catalyst for hydrogen production provided by the present invention can efficiently produce hydrogen in the steam reforming reaction of hydrocarbons containing oxygen molecules.

  Catalysts C, L, and M all showed a higher post-degradation conversion rate than catalyst N, although the rhodium content was less than half that of catalyst N. From these results, the reforming catalyst for hydrogen production provided by the present invention can ensure high durability even in a state where the amount of expensive rhodium used is lower than the catalyst N of Comparative Example 4, It shows that it is possible to produce hydrogen that is inexpensive and highly durable.

  From the above examples, with the hydrogen production reforming catalyst of the present invention, in hydrogen production using hydrocarbon compounds containing oxygen atoms as raw materials, it is possible to efficiently produce hydrogen at low cost and high durability. It will be shown.

  The reforming catalyst for hydrogen production of the present invention is inexpensive and durable in hydrogen production using hydrogen sources such as hydrocarbons as raw materials, and can efficiently produce hydrogen under a wide range of conditions. Very useful. In particular, it is useful for a fuel cell system. Further, according to the reforming catalyst for hydrogen production of the present invention, even in hydrogen production containing oxygen atoms and using a hydrogen source such as hydrocarbon as a raw material, it is inexpensive, durable and efficiently produces hydrogen. Is possible.

  DESCRIPTION OF SYMBOLS 1 ... Water tank, 2 ... Water pump, 3 ... Fuel tank, 4 ... Fuel pump, 5 ... Desulfurizer, 6 ... Vaporizer, 7 ... Reformer, 8 ... Air blower, 9 ... Shift reactor, 10 ... One Carbon oxide selective oxidation reactor, 11 ... anode, 12 ... cathode, 13 ... solid polymer electrolyte, 14 ... electric load, 15 ... exhaust port, 16 ... solid polymer fuel cell, 17 ... heating burner, 20 ... Supply department.

Claims (16)

An inorganic composite oxide support containing alumina and supporting a rare earth metal oxide and an alkaline earth metal oxide, and a nickel and platinum group metal supported on the support,
In the catalyst, the nickel and the platinum group metal are supported on the same carrier, rhodium is contained as the platinum group metal, and rhodium in the carrier diameter direction passing through the center of the catalyst cross section by an electron probe microanalyzer (EPMA). When the line analysis measurement is performed, the ratio of the characteristic X-ray intensity of rhodium detected in the range of a distance within 10% of the carrier diameter from the outer surface of the carrier to the characteristic X-ray intensity of all the detected rhodium is 90% or more. A reforming catalyst for producing hydrogen, wherein the ratio of the characteristic X-ray intensity of rhodium detected within a distance within 20% of the carrier diameter from the outer surface of the carrier is 95% or more.   The supported amount of nickel is 1 to 30 parts by mass in terms of nickel atoms with respect to 100 parts by mass of alumina, and the supported amount of rhodium is 0.01 to 3 parts by mass in terms of rhodium with respect to 100 parts by mass of alumina. The reforming catalyst for hydrogen production according to claim 1, which is a part.   The reforming catalyst for hydrogen production according to claim 1 or 2, wherein the supported amount of the platinum group metal is 0.01 to 3 parts by mass in terms of platinum group metal atoms with respect to 100 parts by mass of the alumina.   The reforming catalyst for hydrogen production according to any one of claims 1 to 3, wherein an amount of the rare earth metal oxide supported is 2 to 30 parts by mass with respect to 100 parts by mass of the alumina.   The reforming catalyst for hydrogen production according to any one of claims 1 to 4, wherein the supported amount of the alkaline earth metal oxide is 0.1 to 10 parts by mass with respect to 100 parts by mass of the alumina.   The combination of the rare earth element contained in the rare earth metal oxide and the alkaline earth element contained in the alkaline earth metal oxide is strontium and cerium, magnesium and cerium, barium and cerium, strontium and lanthanum, and barium and lanthanum. The reforming catalyst for hydrogen production according to any one of claims 1 to 5, wherein the reforming catalyst is at least one selected from.   The reforming catalyst for hydrogen production according to claim 1, wherein the alkaline earth metal oxide is strontium oxide, and the platinum group metal is rhodium and platinum.   The supported amount of nickel is 1 to 30 parts by mass in terms of nickel atoms with respect to 100 parts by mass of alumina, and the supported amount of rhodium is 0.01 to 3 parts by mass in terms of rhodium with respect to 100 parts by mass of alumina. The reforming catalyst for hydrogen production according to claim 7, wherein the supported amount of platinum is 0.001 to 0.3 parts by mass in terms of platinum atoms with respect to 100 parts by mass of alumina.   The reforming catalyst for hydrogen production according to claim 7 or 8, wherein an amount of the strontium oxide supported is 0.1 to 10 parts by mass with respect to 100 parts by mass of the alumina.   The reforming catalyst for hydrogen production according to any one of claims 7 to 9, wherein an amount of the rare earth metal oxide supported is 2 to 30 parts by mass with respect to 100 parts by mass of the alumina. A method for producing a reforming catalyst for hydrogen production according to any one of claims 1 to 10,
A reforming catalyst for hydrogen production, comprising a step of calcining the inorganic composite oxide support or a precursor thereof at a temperature of 650 to 1200 ° C. in the presence of oxygen before supporting the rhodium on the inorganic composite oxide support. Manufacturing method.   A hydrogen production method, wherein hydrogen is obtained by reforming a hydrogen raw material containing hydrocarbon compounds with the reforming catalyst for hydrogen production according to any one of claims 1 to 10.   A hydrogen raw material containing oxygen molecules and hydrocarbon compounds, wherein the oxygen molecule content is 5% by volume or less, is steam-reformed with the reforming catalyst for hydrogen production according to any one of claims 7 to 10. To produce hydrogen. A reforming unit having the reforming catalyst for hydrogen production according to any one of claims 1 to 10, a gas containing at least one selected from oxygen and steam in the reforming unit, and hydrocarbon compounds A supply unit for supplying a hydrogen raw material containing
An apparatus for producing hydrogen, wherein a product containing hydrogen is obtained from the hydrogen raw material by at least one reaction selected from a partial oxidation reaction, an autothermal reforming reaction, and a steam reforming reaction. The reforming unit has the reforming catalyst for hydrogen production according to any one of claims 7 to 10,
The supply unit supplies the reforming unit with a gas containing steam and a hydrogen raw material containing oxygen molecules and hydrocarbon compounds, and contains hydrogen from the raw material by a steam reforming reaction. The hydrogen production apparatus of Claim 14 which obtains a thing.   A fuel cell system comprising the hydrogen production apparatus according to claim 14.