JP2007069105A - Catalyst and its manufacturing method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To aim an improvement in oxidation resistance, which is the biggest problem in a nonmetallic material in sprite of a low cost, relating to a reforming catalyst modifying an alcohol fuel to get out hydrogen, and a shift catalyst transforming CO in a reformed gas to CO<SB>2</SB>to remove. <P>SOLUTION: A spinel structure multiple oxide CuAl<SB>2</SB>O<SB>4</SB>is subjected to a reduction treatment at high temperatures to obtain a stable constitution in which Cu particles are highly dispersed on a surface. Similarly, a simultaneous deposition of a metal Co and a metal Cu is aimed from a composite material of CuAl<SB>2</SB>O<SB>4</SB>and CoAl<SB>2</SB>O<SB>4</SB>. The catalyst obtained in such a manner can facilitate an oxidation and recovery while maintaining excellent catalyst capacities. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a fuel reforming catalyst for hydrogen production, particularly a steam reforming catalyst for hydrocarbon liquid fuels such as methanol and dimethyl ether, a shift catalyst for shift reaction for reducing CO concentration, or a liquid fuel. The present invention relates to a catalyst that can be used in a reaction for synthesis, a reformer using the catalyst, a fuel cell system using the catalyst, and a method for producing the catalyst.

  A polymer electrolyte fuel cell (PEFC) is expected to be widely used as a power source for general households or mobile devices because it operates at a low temperature and can be miniaturized.

  The fuel for PEFC is hydrogen. From the viewpoint of efficiency and cost, a method of extracting hydrogen by performing a “reforming” reaction of a hydrocarbon-based fuel and supplying it to a fuel cell is an effective method.

  Here, it is the reforming catalyst that plays a role in the reaction, and the performance of the CO shift catalyst that lowers the concentration of carbon monoxide contained in the reformed mixed gas is also important.

  Generally, these catalysts are required to have high reactivity and selectivity of generated gas. Cu-based materials are cheaper and more readily available than precious metal-based materials, and are superior in their performance, so they have already been adopted in some fuel cell systems. However, the greatest weaknesses of Cu-based materials are oxidation resistance and sintering resistance. Once exposed to the atmosphere, it oxidizes with sudden heat generation, causing the Cu particles to aggregate and reduce the activity. Further, particle growth, that is, sintering occurs at a temperature exceeding 300 ° C. For this reason, in use, strict temperature control and measures to prevent air contamination are required.

  However, in future fuel cell systems, frequent start and stop operations are required from the viewpoint of energy saving, and from the viewpoint of efficiency improvement and downsizing, a design that allows air to gradually enter when the system is stopped, or shutdown A system that purges with air after steam purge is sometimes studied. These problems are indispensable elements especially when used for mobile use. Therefore, it is difficult to use a conventional Cu-based material that must avoid strict temperature control and air mixing.

  As one of the conventional Cu-based material catalysts, particles containing a Cu component as a catalyst precursor are deposited on a ceramic porous substrate such as alumina by a precipitation method, etc., and after firing, the particles are reduced to precipitate Cu particles. There is something. The Cu particles produced by this method have a small particle size and a large specific surface area, but the particles are in an overlapping state. For this reason, once the oxidation occurs once in contact with the atmosphere, the particles easily aggregate and coalesce, resulting in a problem that the specific surface area is lowered and the activity is consequently lowered.

Moreover, regarding the Cu—Zn / Al ₂ O ₃ -based catalyst, Patent Document 1 proposes a catalyst preparation method by a coprecipitation method. The powder obtained by the coprecipitation method is calcined at a low temperature (300 to 600 ° C.) to obtain a catalyst precursor, which is then reduced to precipitate Cu particles on a ceramic porous substrate such as alumina. It is. The Cu particles precipitated by reduction by appropriately adjusting the amount ratio of each component are said to have good dispersibility and little sintering (aggregation) due to heat.

  However, the catalyst obtained by this method has a problem in the adhesion (bonding) between the Cu particles and the substrate, and its durability becomes a problem when used for a long time.

In these methods, the catalyst precursor before reduction has a composition containing CuO or Cu ₂ O, and therefore the temperature at which Cu is precipitated may be about 150 ° C. to 300 ° C.

On the other hand, Non-Patent Document 1 and Non-Patent Document 2 report on a catalyst obtained by reducing spinel complex oxide. In this document, a catalyst obtained by reduction treatment of a Cu—Al, Cu—Mn, or Cu—Mn—Fe spinel composite oxide is evaluated, and a Cu—Mn, Cu—Mn—Fe catalyst is evaluated. It is said that a catalyst obtained by reducing the spinel complex oxide is the most active. However, base materials such as MnO formed by reduction of these have problems in terms of mechanical strength, and since Mn can take several valences, there is a concern about stability due to long-term use. In this document, the reduction temperature of the spinel complex oxide is set to about 250 to 300 ° C. in consideration of grain growth. Therefore, the Cu—Al-based spinel complex oxide CuAl ₂ O ₄ catalyst disclosed in Non-Patent Document 2 has low catalytic activity despite a large specific surface area. This is probably because the reduction temperature is as low as 250 to 300 ° C., and that Cu is being deposited (the amount of Cu deposited is small).

On the other hand, our previous research has revealed that Co-based catalysts prepared by reduction deposition show excellent CO concentration reduction and selectivity in the CO gas shift reaction. However, when an oxide such as Co ₃ O ₄ is formed on the surface of a Co-based catalyst under high-temperature oxidation conditions, the oxide is extremely stable, and thus the catalytic activity is lost. It has been confirmed that the original metal state cannot be restored unless heat treatment is performed at a temperature of 350 ° C. or higher in an atmosphere of at least sufficiently high reducibility. In particular, reduction is not easy in an atmosphere where CO ₂ coexists, such as a reformed gas, and a higher temperature of 400 to 500 ° C. is required. Co-based materials are useful not only for CO shift reaction but also for reforming hydrocarbon fuels and as catalysts for liquid fuel synthesis. Taking measures against oxidation broadens the range of use. Of particular importance.

JP 2004-202310 A Appl. Catal. A: Genaral, 242, 287 (2003) Proceedings of the 94th Catalysis Conference, 390 (2004))

As described above, a catalyst using a Cu-based material is cheaper and easier to obtain than a noble metal-based catalyst, and is expected as a reforming catalyst, a CO shift catalyst, and the like. There are disadvantages in that it is inferior in properties such as oxidization property, sintering resistance, adhesion between the substrate and metal particles, and catalyst performance.
Co-based materials are also cheaper and easier to obtain than noble metal-based catalysts, and are expected as reforming catalysts, CO shift catalysts, and liquid fuel synthesis catalysts. There is a problem that it is not.

The present invention has been made in view of the above problems, and is a Cu-based material that has excellent oxidation resistance, sintering resistance, adhesion between a base material and metal particles, long life, and good catalytic performance. And a reformer and a fuel cell system using the same.
Another object of the present invention is to provide a Co-based catalyst that exhibits high catalyst performance and can be easily restored (reduced) after oxidation, and a reformer and a fuel cell system using the same.

The first catalyst of the present invention is a catalyst obtained by reducing a catalyst precursor using a Cu-aluminate spinel type composite oxide, wherein at least the surface layer portion contains Al ₂ O ₃ and is spinel type. The diffraction intensity of the (311) plane, which is the strongest line in the X-ray diffraction of the composite oxide CuAl ₂ O ₄ , is at least one of CuAlO ₂ and Al ₂ O ₃ and 5% of the strongest line diffraction intensity of each of Cu A catalyst comprising the following oxide and metal Cu particles embedded and dispersed in the oxide.

  The first catalyst production method of the present invention is a catalyst production method characterized by subjecting a catalyst precursor of a Cu-aluminate spinel composite oxide to a reduction heat treatment at a temperature of 350 ° C. or higher and 1000 ° C. or lower. It is.

The second catalyst of the present invention is a catalyst obtained by reducing a catalyst precursor using a Cu-aluminate spinel composite oxide and a Co-aluminate spinel oxide, and at least the surface layer portion is made of Al _2. The diffraction intensity of the (311) plane that contains O ₃ and is the strongest line in the X-ray diffraction of the spinel-type composite oxide CuAl ₂ O ₄ is at least one of CuAlO ₂ and Al ₂ O ₃ and each of Cu Characterized by comprising an oxide that is 5% or less with respect to the strongest line diffraction intensity, metal Cu particles embedded and dispersed in the oxide, and metal Co particles embedded and dispersed in the oxide. Catalyst.

  In the second catalyst production method of the present invention, a catalyst precursor using a Cu-aluminate spinel composite oxide and a Co-aluminate spinel composite oxide is reduced at a temperature of 600 ° C. or higher and 1000 ° C. or lower. It is a manufacturing method of the catalyst characterized by heat-processing.

  The third catalyst of the present invention is a catalyst characterized by blending the first catalyst and a solid acid catalyst.

  The fourth catalyst of the present invention is a catalyst characterized by blending the second catalyst and a solid acid catalyst.

  Further, the present invention includes the first catalyst to the fourth catalyst, a carrier that supports the catalyst, and a container that stores the carrier that supports the catalyst, and is supplied from the outside. The reformer is characterized in that hydrogen is extracted from the reaction product by reacting the fuel and water vapor in the vessel.

  Further, the present invention is a fuel cell system comprising a fuel cell, the reformer, and a hydrogen supply path for supplying hydrogen taken out by the reformer to the fuel cell. .

<About the first catalyst (Cu-based catalyst)>
In obtaining a Cu material-based catalyst, the present inventors use a Cu-aluminate spinel type complex oxide as a catalyst precursor, and reduce this under high temperature conditions to obtain an excellent Cu material-based catalyst. I found it.

When the Cu-aluminate spinel type composite oxide is reduced, at least the constituent phase of the surface layer part is changed with the precipitation of the metal Cu particles, and the base material composition becomes a composite mainly composed of Al ₂ O ₃ and CuAlO ₂ . When the reduction is further advanced, the material becomes substantially only the metal Cu and Al ₂ O ₃ , and at this time, it is confirmed at least by X-ray diffraction that the spinel-type composite oxide CuAl ₂ O ₄ hardly remains in the surface layer portion. In such a state, the catalyst performance is stable and high. The catalyst thus obtained is present in a dispersed form in such a manner that fine Cu particles are partially embedded in the base oxide, and has strong adhesion (bonding) with the base. It has a certain catalyst / substrate integrated structure. The metal Cu particles dispersed in such a manner that they are embedded have high catalytic activity and are difficult to cause sintering and aggregation due to oxidation or the like. Further, since the bond with the substrate is strong, desorption hardly occurs. Moreover, even if CuO or Cu ₂ O exists on the surface, the metal Cu particles themselves are easily reduced and regenerated at about 200 ° C., and can be used repeatedly and stably.

<About the second catalyst (Co-based catalyst)>
In obtaining a Co material-based catalyst, the inventors of the present invention have a Cu-aluminate spinel-type composite oxide and a Co-aluminate spinel oxide at the same time, and are subjected to a reduction heat treatment under a high temperature condition, thereby Reduction of Co is promoted by the presence thereof, and a catalyst in which metal Cu particles are deposited together with metal Co particles on the oxide is obtained. Also, even when this catalyst is oxidized, the presence of metal Co particles It has been found that reduction of particles is promoted again, and a catalyst that can be easily restored to its original state after oxidation without deteriorating the catalyst performance. For example, after forcibly oxidizing this catalyst once, it is simply put in a reformed gas containing about 20% of CO ₂ (including about 35% of H ₂ ), and if it is raised to 350 ° C., the catalyst is regenerated. .

The catalyst needs to be subjected to a reduction heat treatment so that at least the spinel-type composite oxide CuAl ₂ O ₄ does not substantially remain in the surface layer portion. Further, when reducing heat treatment is performed under the above conditions, CoAl ₂ O ₄ tends to be reduced and hardly remain. The catalyst thus obtained exists in such a form that the metal Cu particles and the metal Co particles are partially embedded in the base oxide, and the adhesion (bonding) with the base material is strong. It has a certain catalyst / substrate integrated structure. In addition, Cu particles and Co particles dispersed in an embedded form have high catalytic activity and are difficult to sinter or aggregate due to oxidation or the like. Further, since the bond with the substrate is strong, desorption hardly occurs.

According to the present invention, it is possible to obtain a catalyst using a Cu-based material that is excellent in oxidation resistance, sintering resistance, and adhesion between a base material and metal particles, has a long life, and has good catalytic performance.
In addition, the present invention can provide a Co-based catalyst that exhibits high catalyst performance and can be easily restored (reduced) after oxidation.
As described above, according to the present invention, it is possible to maintain the performance after oxidation, which is a drawback of the non-noble metal catalyst, and it is possible to provide an inexpensive material and to greatly improve the performance as a catalyst. Become.

  Moreover, the reformer using these catalysts can provide a reformer having a high fuel reforming ability and a long life because the catalyst provided has the above-described effects.

In addition, the fuel cell system using this reformer is characterized by high efficiency and a long use period. Furthermore, since it has resistance to oxidation, it is possible to design a design that allows slow oxygen entry from the subsequent stage, especially when the system is shut down, and eliminates the need for N ₂ gas purge (no need for a purge cylinder). In order to make this possible, the system can be made smaller and more compact.

<First catalyst (Cu-based catalyst)>
Hereinafter, the first catalyst will be described.
The first catalyst is obtained by reducing a catalyst precursor using a Cu-aluminate spinel composite oxide. At this time, at least the surface layer portion contains Al ₂ O ₃ and the diffraction intensity of the (311) plane which is the strongest line in the X-ray diffraction of the spinel-type composite oxide CuAl ₂ O ₄ is CuAlO ₂ or Al ₂ O ₃ . At least one of the above, an oxide of 5% or less with respect to the strongest line diffraction intensity of Cu, and metal Cu particles embedded and dispersed in the oxide.
The oxide constituting the first catalyst contains Al ₂ O ₃ not only in the surface layer portion but also in the interior, and is the strongest line in the X-ray diffraction of the spinel-type complex oxide CuAl ₂ O ₄ (311). The surface may have a diffraction intensity of 5% or less with respect to each of the strongest line diffraction intensities of CuAlO ₂ and Al ₂ O ₃ and Cu.

  The oxide preferably further contains Ti. Particles containing Ti are densified and have high strength as a substrate. In particular, it is optimal when the entire catalyst is used in a porous form. The Ti content is preferably in the range of 0.01 to 2% by weight in terms of the amount of metal in the state of the catalyst precursor before the reduction in order not to greatly change the performance as a catalyst. At this time, titanium may be contained in the form of a compound formed in the oxide sintered body, but is not limited thereto.

  It is desirable that the oxide further contains Zn. Particles containing Zn are improved in activity and stability. The Zn content is preferably in the range of 10 wt% to 50 wt% in terms of the amount of metal in the state of the catalyst precursor before the reduction in order to enhance the catalytic performance of Cu. At this time, Zn may be contained in the form of a compound. For example, Zn is preferably contained in the form of ZnO, but is not limited thereto.

  There are no particular limitations on the size and shape of the oxide serving as the substrate on which the metal Cu particles are deposited on the surface. For example, in general, particles having an average particle diameter of about 1 μm to 10 μm are exemplified, but the present invention is not limited thereto.

At least 95% of the metal Cu particles embedded and dispersed in the oxide preferably have a particle size of 200 nm or less. If the Cu particles are larger than this, the specific surface area of the catalyst will decrease, and the distance between adjacent particles will increase, and coalescence and agglomeration will easily occur between the particles during oxidation, which may reduce performance. Because there is. In order to maintain the catalyst performance, it is desirable that at least 95% of the metal Cu particles embedded and dispersed in the oxide is at least 5 nm in particle size in the initial production state.
In addition, the particle size of the metal Cu particles described above is a value measured from the particle size measurement of the metal Cu particles by surface observation with an SEM photograph.

  In the first catalyst, the total amount of Cu contained in the catalyst is desirably in the range of 5 to 40% by weight, but is not limited thereto.

  The state in which the particles are embedded and dispersed in the oxide means that some of the metal nanoparticles reduced and precipitated from the base material exist in a state of being dispersed and embedded in the base oxide. This means that the interface between the oxide and the particles is bonded with good consistency.

<Manufacturing method>
The first catalyst as described above can be obtained by subjecting a catalyst precursor using a Cu-aluminate spinel composite oxide to a reduction heat treatment under a specific temperature condition.
This will be described in detail below.

<Catalyst precursor>
Specifically, the Cu-aluminate spinel type complex oxide used as the catalyst precursor is desirable because CuAl ₂ O ₄ has advantages such as easy production. Further, it may be a CuAlO _2, may be a mixture of CuAl ₂ O ₄ and CuAlO _2. The catalyst precursor may contain unreacted raw material Al ₂ O ₃ .

The process for obtaining the catalyst precursor is not particularly limited. For example, there is a method of sintering after mixing an aluminum compound and a copper compound as raw materials. Specifically, a metal salt such as copper nitrate and aluminum nitrate is used as a raw material, and these are mixed in a predetermined ratio to form an aqueous solution, dried and fired, or a raw material of CuO and Al ₂ O ₃ and mixed in a predetermined ratio. There is a method of firing. For example, CuAl ₂ O ₄ can be obtained by mixing and firing CuO and Al ₂ O ₃ at a molar ratio of about 1: 1.

  The smaller the particle size of the raw material powder used in these methods, the better because it can be densified to give strength. However, densification may be promoted by combining gas pressurization or pressing at the time of firing.

In addition to increasing the density of the catalyst precursor by increasing the sinterability and increasing the density of the catalyst precursor, and adding the Ti component in addition to the aluminum compound and copper compound as raw materials It is desirable to do. Examples of the Ti component include titanium compounds such as titanium oxide such as TiO ₂ . The Ti component is preferably added so as to be 0.012 wt% or more and 2 wt% or less in terms of metal with respect to the amount of metal element contained in the entire catalyst precursor (sintered body). This is because if the amount is less than 0.01% by weight, the effect of addition is small, and if it exceeds 2% by weight, the shrinkage during sintering may be greatly broken.

  In order to improve the catalytic activity and stability, it is also desirable to add a Zn component in addition to the aluminum compound and the copper compound as raw materials. Examples of the Zn component include zinc compounds such as zinc oxide such as ZnO. The Zn component is desirably 10 wt% or more and 50 wt% or less in terms of metal with respect to the entire catalyst precursor (sintered body).

  The calcination (heat treatment) temperature for obtaining the catalyst precursor is preferably 700 ° C. or higher and 1300 ° C. or lower. More preferably, it is 900 degreeC or more and 1200 degrees C or less. In the study so far, in the method of forming metal particles by reduction precipitation from the inside, the influence of the specific surface area of the composite oxide itself as the base material is relatively small, and it is not necessary to prepare a catalyst precursor having a high specific surface area. It has become clear. In the case of an integral catalyst, it is considered that it is more effective to increase the sinterability and increase the strength. For this reason, the above temperature range is considered appropriate. The appropriate strength of the base material is an especially important factor when the base material itself is structured and made porous to be used as a monolithic catalyst.

Incidentally, upon obtaining a spinel-type composite oxide CuAl ₂ O _4, the system is mixed and fired to obtain the composition of the single-phase or _Al 2 _{O 3} phase rich side. This is because if a CuO phase or a Cu ₂ O phase remains in the sintered body, Cu precipitates at a lower temperature, resulting in a non-uniform structure.

<Reduction heat treatment>
A reduction heat treatment is performed on the catalyst precursor obtained as described above. The reduction heat treatment may be a heat treatment in a hydrogen atmosphere or a method in which heat treatment is performed simultaneously with a reducing substance such as carbon in an inert gas.

  As described above, when the catalyst precursor of the Cu-aluminate spinel type complex oxide is used, the heat treatment temperature during the reduction treatment is 350 ° C. or higher and 1000 ° C. or lower. More preferably, it is 400 degreeC or more and 800 degrees C or less.

Considering the use temperature of the catalyst normally assumed to be 250 to 350 ° C., it is required that the reduction heat treatment of Cu be performed at a temperature higher than that. In addition, CuAl ₂ O ₄ , which is a spinel-type Cu-aluminate spinel-type composite oxide, starts deposition of metallic Cu by heating around 350 ° C., and becomes a composite of Al ₂ O ₃ and CuAlO ₂ . In the vicinity of 600 ° C., precipitation of Cu from this CuAlO ₂ also starts. If the reduction heat treatment temperature is lower than 350 ° C., metal Cu may not be sufficiently precipitated, and a large amount of Cu-aluminate spinel type complex oxide CuAl ₂ O ₄ remains. If a large amount of this substance remains, precipitation may occur due to hydrogen generated by the reforming reaction during use, and the performance may not be stable. In addition, when the temperature is higher than 1000 ° C., the already precipitated Cu particles may be combined and grown.

  Although the reduction heat treatment time depends on the reduction temperature, it is preferable to secure a time for causing sufficient precipitation of Cu particles. Specifically, for example, it is several minutes to several hours, and it is preferable to adjust the temperature and time so that the weight loss upon reduction is about 2 to 8%.

Incidentally, when obtaining a commercially available Cu—Zn / Al ₂ O ₃ -based catalyst, as a result of thermogravimetric analysis (TG), a Cu-based oxide coated on an Al ₂ O ₃ substrate is used as a catalyst precursor. Cu precipitation by reduction starts from around 150 ° C. Therefore, the reduction heat treatment is a much lower temperature of 150 ° C. to 200 ° C.

In addition, the catalyst obtained by reducing heat treatment of the spinel-type composite oxide CuAl ₂ O ₄ shown in Non-Patent Document 1 was not active despite the large specific surface area because the reducing heat treatment temperature was as low as 250 to 350 ° C. It is considered that the precipitation of Cu is not sufficient and CuAl ₂ O ₄ remains.

<Second catalyst (Co-based catalyst)>
Hereinafter, the second catalyst will be described.
The second catalyst is obtained by reducing a catalyst precursor using a Cu-aluminate spinel type composite oxide and a Co-aluminate spinel oxide. At least the surface layer portion contains Al ₂ O ₃ and the diffraction intensity of the (311) plane which is the strongest line in the X-ray diffraction of the spinel-type composite oxide CuAl ₂ O ₄ is at least of CuAlO ₂ and Al ₂ O ₃ 1 type, an oxide of Cu that is 5% or less with respect to each strongest line diffraction intensity, metal Cu particles having an average particle diameter of 5 nm to 200 nm embedded in the particles, and dispersed in the particles Embedded Co particles having an average particle diameter of 5 nm to 200 nm.

The oxide constituting the second catalyst contains Al ₂ O ₃ not only in the surface layer portion but also in the interior, and is the strongest line in the X-ray diffraction of the spinel complex oxide CuAl ₂ O ₄ (311) plane. The diffraction intensity may be 5% or less with respect to at least one of CuAlO ₂ and Al ₂ O ₃ and the strongest line diffraction intensity of Cu.

  The average particle diameter of the base material oxide on which metal Cu particles are deposited on the surface is not particularly limited. For example, generally those having a particle size of about 1 μm to 10 μm can be mentioned, but the present invention is not limited thereto.

  It is preferable that at least 95% of the metal Cu particles embedded in the oxide have a particle size of 200 nm or less. If the Cu particles are larger than this, the specific surface area of the catalyst will decrease, and the distance between adjacent particles will increase, and coalescence and agglomeration will easily occur between the particles during oxidation, which may reduce performance. Because there is. In order to maintain catalyst performance, it is desirable that at least 95% of the metal Cu particles embedded and dispersed in the oxide have a particle size of 5 nm or more.

  It is preferable that at least 95% of the metallic Co particles embedded in the oxide have a particle size of 200 nm or less. If the Co particles become larger than this, the specific surface area of the catalyst will decrease, and the distance between adjacent particles will increase, and coalescence and agglomeration will easily occur between the particles during oxidation, which may reduce performance. Because there is. Further, it is desirable for maintaining the catalyst performance that at least 95% of the metallic Co particles embedded and dispersed in the oxide have a particle size of 5 nm or more.

  The amount of metal Co embedded in the oxide in the second catalyst is preferably in the range of 5 to 40% by weight, but is not limited thereto.

  In the second catalyst, Cu mainly serves to facilitate the reduction and regeneration of Co particles. Therefore, the amount of metal Cu with respect to the amount of metal Co embedded in the oxide is desirably 0.01 mol% or more and 5 mol% or less. More preferably, it is 0.01 mol% or more and 2 mol% or less. If the amount is less than 0.01 mol%, the properties of Co that are difficult to be reduced appear, and if added in an amount of 2 mol% or more, the properties of Cu are emphasized.

<Manufacturing method>
In order to obtain the second catalyst as described above, a catalyst precursor using a Cu-aluminate spinel-type composite oxide and a Co-aluminate spinel-type composite oxide is subjected to a reduction heat treatment at a specific temperature condition to form a metal. It is obtained by simultaneously depositing Cu and metal Co. This will be described in detail below.

<Catalyst precursor>
Examples of the Cu-aluminate spinel complex oxide used as the catalyst precursor include CuAl ₂ O ₄ or CuAlO ₂ , and CuAl ₂ O ₄ is preferable because it has advantages such as easy manufacture. A mixture of CuAlO ₂ and CuAl ₂ O ₄ may be used.

Specific examples of the Co-aluminate spinel complex oxide include CoAl ₂ O ₄ or CoAlO ₂ , and CoAl ₂ O ₄ is preferable because it is easier to manufacture. It may be a mixture of CoAlO ₂ and CoAl ₂ O ₄ .

As for a catalyst precursor, it is desirable that Cu-aluminate spinel type complex oxide and Co-aluminate spinel type complex oxide form a complex. The catalyst precursor may contain unreacted raw material Al ₂ O ₃ .

The process for obtaining the catalyst precursor is not particularly limited. For example, there is a method of obtaining a composite by mixing an aluminum compound, a copper compound, and a cobalt compound as raw materials and then sintering the mixture. The raw materials may be mixed by a solution method (metal salt aqueous solution mixing, coprecipitation method, sol-gel method, etc.), or powder mixing. Specifically, for example, there is a method in which oxide powder is used as a starting material, CuO, CoO, and Al ₂ O ₃ are mixed at a desired ratio, press-molded, and sintered in an electric furnace.

  The temperature of calcination (heat treatment) when obtaining the catalyst precursor is preferably 700 ° C. or higher and 1300 ° C. or lower in order to obtain a sintered body having an appropriate density. More preferably, it is 900 degreeC or more and 1200 degrees C or less.

It is preferable not to leave the oxide such as CuO and Cu ₂ O and CoO and _Co 3 _{O 4} as possible in the sintered body. If many of these remain, Cu or Co precipitates at a lower temperature during the reduction, and the structure finally formed may become non-uniform. The sintered body is more preferably composed of only two phases of CuAl ₂ O ₄ and CoAl ₂ O ₄ , but the Al ₂ O ₃ phase may exist in excess.

<Reduction heat treatment>
A reduction heat treatment is performed on the catalyst precursor obtained as described above. The reduction heat treatment may be a heat treatment in a hydrogen atmosphere or a method in which heat treatment is performed simultaneously with a reducing substance such as carbon in an inert gas.

In the spinel-type composite oxide CoAl ₂ O ₄ , precipitation of metallic Co is started by heating at around 700 ° C. to produce CoAlO ₂ , and thereafter, from around 850 ° C., metallic Co is further precipitated from CoAlO ₂ and finally, The base material is only Al ₂ O ₃ . It has been clarified that when both Cu-based and Co-based spinel composite oxides are simultaneously contained, the reduction start temperature shifts to a higher temperature side than the reduction temperature of the Cu-based spinel composite oxide alone. In view of the above points, the reduction temperature is preferably 600 ° C. or higher and 1000 ° C. or lower, more preferably 800 ° C. or higher and 1000 ° C. or lower. When the temperature is lower than 600 ° C., a metal deposition amount sufficient to exhibit catalyst performance cannot be obtained. When the temperature is higher than 1000 ° C., grain growth of precipitated particles occurs, which also causes a decrease in catalytic activity.

  Although the reduction heat treatment time depends on the reduction temperature, it is preferable to ensure the time for sufficient precipitation of the metal Cu particles and metal Co particles. Specifically, for example, it is several minutes to several hours, and it is preferable to adjust the temperature and time so that the weight loss upon reduction is about 2 to 8%.

<How to use the catalyst>
The first and second catalysts according to the present invention can be usefully used as, for example, liquid fuel reforming and CO shift catalysts used in stationary reforming fuel cells and mobile fuel cells.

Specifically, the liquid fuel is useful as a reforming catalyst for hydrocarbon fuels such as dimethyl ether (DME) as well as methanol. In particular, since DME is safe and harmless and can be easily vaporized, it is a fuel that is a promising fuel candidate like methanol, and a catalyst capable of reforming this fuel is very useful. . The reforming of DME proceeds by the following two-stage reaction. One is hydrolysis of DME, which proceeds to decomposition into methanol. The other is to efficiently reform the produced methanol and take out H ₂ .

  The second catalyst has a relatively high temperature for reforming and shift reactions (50-100 ° C. higher than the Cu-based catalyst) compared to the Cu-based catalyst and the noble metal-based catalyst, but the selectivity of the reaction. And high catalytic activity, it is useful as a reforming or shift catalyst. This catalyst is also useful as a catalyst for synthesizing liquid fuel such as methanol.

  The first catalyst or the second catalyst of the present invention is a combination of a solid acid catalyst having a high hydrolysis promoting action and a catalyst (third catalyst) or a second catalyst in which the first catalyst and the solid acid catalyst are blended. The use of a catalyst containing a solid acid catalyst (fourth catalyst) is particularly useful as a catalyst for DME reforming. These combinations can have both high catalytic activity and durability that can be repeated any number of times even when exposed to the atmosphere.

At this time, as the solid acid catalyst, at least two components composed of γ-Al ₂ O ₃ , θ-Al ₂ O ₃ , anatase type titania, zirconia, zeolite, metallosilicate, heteropolyacid, and Ti, Si, Al, and Zr are used. The composite oxide containing the above is mentioned. These may be used alone or in combination.

  The blending ratio of the solid acid catalyst is desirably 30% by weight or more and 70% by weight or less with respect to the first catalyst or the second catalyst. If the amount is small, hydrolysis does not occur sufficiently, and if the amount is too large, the modification is not sufficient.

  According to the first catalyst production method or the second catalyst production method of the present invention, the metal that is the catalyst component is precipitated from the catalyst precursor, the remainder is used as the base material, and the catalyst component and the base material are integrated. It becomes.

  Therefore, the catalyst precursor can be preliminarily formed into a pellet, honeycomb, foam, or sheet, followed by firing and reduction heat treatment. This can be expected to be more effective especially when it is desired to give a complicated shape as a catalyst or when a reactor having a very fine structure is produced. In particular, the advantage of the first catalyst manufacturing method or the second catalyst manufacturing method of the present invention is that, even in a sample of any shape, metal particles are deposited on the surface portion after molding and sintering. In some cases, a catalyst structure can be formed. As a result, a uniform and stable catalyst structure can be formed particularly in the inside of a finely processed groove or a sample surface portion having a complicated shape.

  Of course, it is also possible to pulverize and pulverize the catalyst precursor once calcined, attach it to the support having the shape processed with ceramics or metal, and then reduce it before use.

  The case where the first to fourth catalysts of the present invention are used in a reformer will be described. As an example of the configuration of the reformer, a configuration in which the first catalyst to the fourth catalyst of the present invention are made into particles and stored in a container is given as an example.

The configuration of a hydrocarbon fuel reformer according to an embodiment of the present invention is schematically shown in FIG.
In the illustrated hydrocarbon fuel reformer, a liquid fuel such as CH ₃ OH or dimethyl ether (DME) is stored in a hydrocarbon fuel storage tank 10, and water for reforming such fuel is used. And accommodated in the modifier tank 20. The fuel and the reformer are vaporized in the preheating devices 30 and 40, respectively, and introduced into the mixer 50 in the container 60. The mixed gas reacts in the reforming catalyst layer 80 disposed in the container 60 to be reformed into a fuel mainly composed of hydrogen.

  In the illustrated example, the burner 70 is used to uniformly heat the inside of the reforming catalyst layer 80, but combustion heating by the catalyst or a method in which a part of the generated hydrogen is refluxed and burned may be employed. .

  The reforming catalyst layer 80 can be loaded with, for example, a catalyst 110 produced in a honeycomb shape as shown in FIG. In the embodiment of the present invention, metal particles are precipitated from the catalyst precursor by reduction, and therefore, as schematically shown in FIG. 3, the metal particles 90 are formed on the surface of the honeycomb inner wall 100 serving as a flow path for gas or the like. be able to. Further, by using such a honeycomb-shaped catalyst, handling becomes easy and pressure loss with respect to the flow of fuel or reformed gas can be remarkably reduced.

  When the reformed gas obtained from the reformer is used as fuel for the fuel cell, it is directly or through a hydrogen supply path (not shown) from the reformer vessel or a carbon monoxide converter (not shown). To reduce the CO concentration in the reformed gas and then supply it to the fuel electrode of a solid polymer membrane fuel cell or the like (not shown).

  The present invention will be described in more detail with reference to the following examples, but the present invention is not limited to these examples.

(Examples 1, 2, and 3)
CuO powder and Al ₂ O ₃ powder were weighed in an equimolar amount, mixed using a ball mill, pressed into a φ21 mm × 4 mm pellet, and sintered in an atmospheric furnace at 1100 ° C. for 2 hours. The composition of the obtained sintered body (catalyst precursor) was identified with an X-ray diffraction apparatus, and the specific surface area was measured with an N ₂ gas adsorption test apparatus. Next, the sintered body was coarsely pulverized, sieved through a 200 μm mesh, and the larger one was left for a test for CH ₃ OH modification. Using 2 g of the crushed pieces in a 100 cc / min hydrogen stream at 400 ° C. for 10 minutes (Example 1), 600 ° C. for 10 minutes (Example 2), and 900 ° C. for 0 minute (as soon as 900 ° C. is reached) The temperature was lowered.) (Example 3) and reduction treatment were performed to obtain samples for the catalyst test.

Next, a methanol reforming test and an oxidation test were performed on the samples of Examples 1 to 3. The reduced sample was once taken out into the atmosphere and filled in the reaction vessel (reformer) of the test apparatus shown in FIG. (Supplement: Commercially available Cu-based catalysts are not handled in this way. Reduced particles easily oxidize and agglomerate, so do not put them into the atmosphere. (Used after hydrogen reduction.) The liquid is fed by a syringe pump, and the liquid feed is H ₂ O: 100 cc / min (CH ₃ OH: H ₂ ) with respect to CH ₃ OH: 50 cc / min in terms of vaporization. O = 1: 2). Some experiments were also conducted with CH ₃ OH: H ₂ O = 1: 4. A 50 cc / min N ₂ gas was used as a gas carrier and as an internal standard gas. The reformed mixed gas was analyzed by gas chromatography after removing liquid components in a trap tank. The temperature of the vaporizer was 150 ° C., and the temperature of the reformer was changed between 200 ° C. and 350 ° C. The pipes were all made of stainless steel, and were heated to 150 ° C. with a tape heater so that the vaporized gas did not condense on the way.

The reactor was purged with N ₂ gas while maintaining the temperature at 350 ° C., and N ₂ and O ₂ were introduced for about 15 minutes so as to obtain an air composition, thereby oxidizing the sample.

After oxidation, the line was purged again with N ₂ and a reforming experiment was performed as before. After a series of oxidation-modification tests were repeated five times, the experiment was terminated and the material structure was observed with SEM.

Next, a shift test for evaluating the performance as a shift catalyst was performed on the sample of Example 1. A shift reactor was attached to the rear stage of the reformer shown in FIG. 4, and 2 g of the sample was used to fill the shift reactor. Experiments were conducted using reformed gas reformed by actual catalytic reforming as the reformed gas introduced into the shift reactor. 2 g of sample was used and charged into the shift reactor. The composition of the reformed gas used is approximately H ₂ : 32%, CO: 5%, CO ₂ : 8%, CH ₄ : 1%, N ₂ : 20%, H ₂ O: 34%. The change in CO concentration before and after the reaction and the amount of H ₂ produced were examined. Further, after purging with N ₂ gas, N ₂ and O ₂ were introduced for 15 minutes so as to have an air composition at 350 ° C. to be oxidized. The shift test was performed again at 350 ° C. without reducing the oxidized sample. The catalyst performance was evaluated and a sample was taken out after the test and the structure was observed by SEM.

(Comparative Example 1)
Using a commercially available Cu—Zn-based catalyst (tablet), a methanol reforming test and an oxidation test were performed under the same conditions as in Example 1. However, after the reduction treatment was set in the reforming reactor, it was performed at 200 ° C. for 1 hour in a 10% H ₂ / Ar mixed gas stream (the reduction treatment was performed in the reactor, This is to avoid oxidization that will take place if it is taken out to the atmosphere after reduction. In addition, the catalyst precursor of this catalyst has a composition containing CuO or Cu ₂ O.

(Comparative Example 2)
Sample preparation, methanol reforming test and oxidation test were performed in the same manner as in Example 1 except that the reduction temperature of the catalyst precursor prepared in Example 1 was set to 325 ° C. × 10 minutes.

Example 4
A hydrate of copper nitrate and aluminum nitrate was mixed so that the element ratio of Cu and Al was 1: 2, to obtain an aqueous solution. After evaporating water with an evaporator, thermal decomposition treatment was performed in Ar at 110 ° C. for 2 hours and at 500 ° C. for 10 hours. The produced mixed powder was press-molded into a pellet of φ21 mm × 4 mm as a raw material, and sintered at 1100 ° C. for 2 hours in an atmospheric furnace. This sintered body was coarsely pulverized, subjected to hydrogen reduction treatment at 600 ° C. for 10 minutes, and subjected to a methanol reforming test and an oxidation test in the same manner as in Example 1.

(Example 5)
A small amount of TiO ₂ powder is mixed with CuO powder and Al ₂ O ₃ powder weighed in equimolar amounts so that the amount of Ti is 0.3% by weight in terms of metal with respect to the entire catalyst precursor, and wet mixed by a ball mill. Went. After drying the mixed solution, it was molded with a press. The compact was sintered in an atmospheric furnace at 1100 ° C. for 2 hours. The sintered body (catalyst precursor) was coarsely pulverized, subjected to a reduction treatment at 600 ° C. for 10 minutes, and subjected to a methanol reforming test and an oxidation test in the same manner as in Example 1.
A shift test for evaluating the performance as a shift catalyst was performed on the sample prepared in Example 5 in the same manner as in Example 1.

(Example 6)
To the CuO powder and Al ₂ O ₃ powder weighed equimolarly, ZnO powder was added so that the Zn amount was 40 wt% in terms of metal with respect to the entire catalyst precursor, and wet mixing was performed by a ball mill. After drying the mixed solution, it was molded with a press. The molded body was placed in an atmospheric furnace and fired at 1100 ° C. for 2 hours. The obtained sintered body was coarsely pulverized, subjected to reduction treatment at 600 ° C. for 10 minutes, and subjected to a methanol reforming test and an oxidation test in the same manner as in Example 1.

(Example 7)
Exactly the same as Example 6, except that the CuO—Al ₂ O ₃ —ZnO-based material of Example 6 was mixed with TiO ₂ so that the amount of Ti component was 0.3 wt% with respect to the entire catalyst precursor. Samples were prepared, and a methanol reforming test and an oxidation test were conducted in the same manner as in Example 1.

(Example 8)
CuO powder, CoO powder and Al ₂ O ₃ powder were weighed and mixed at a molar ratio of 0.2: 9.8: 10, pressed into a 21 mm diameter pellet, and then heated at 1300 ° C. for 5 hours in an atmospheric furnace. Sintered.

The composition of the obtained sintered body was identified with an X-ray diffraction apparatus, and the specific surface area was measured with an N ₂ gas adsorption test apparatus. Next, the sintered body was coarsely pulverized, sieved through a 200 μm mesh, and the larger one was left for a test for CH ₃ OH modification. Using 2 g of the crushed pieces, in a hydrogen stream of 100 cc / min, the reducing conditions were 900 ° C. for 0 minute, and the temperature was reduced immediately after reaching 900 ° C. The same methanol reforming test as in Example 1 And the oxidation test and the same shift test as in Example 1.

(Comparative Example 3)
A sample was obtained in the same manner as in Example 8 except that the catalyst precursor was obtained only from CoO powder and Al ₂ O ₃ powder without adding CuO powder, and a shift test was conducted in the same manner as in Example 1.

Example 9
The sample of Example 1 and 1.5 g of γ-Al ₂ O ₃ were weighed and mixed to prepare a sample. For easy handling, γ-Al ₂ O ₃ was obtained by pressing and coarsely pulverizing powder (hereinafter, γ-Al ₂ O ₃ was treated in the same manner).

This sample was subjected to a DME modification test and an oxidation test. DME reforming test and the oxidation test, DME: mixing ratio of _{H 2} O is 1: 4 (DME _CH 3 when the hydrolyzed in _CH 3 OH OH: 1 as _{H 2} O ratio: 2 corresponds to) to Except that, the methanol reforming test and the oxidation test of Example 1 were performed.

(Example 10)
The sample of Example 1 and the H-type pentasil-type zeolite were each weighed and mixed by 1.5 g to prepare a sample. As the zeolite catalyst, one previously processed into a solid state was used.
The same DME modification test and oxidation test as in Example 9 were performed on this sample.

(Example 11)
The sample of Example 1 and a tungsten-phosphorus catalyst (H ₃ PW ₁₂ O ₄₀ ), which is a kind of heteropolyacid, were weighed and mixed in an amount of 1.5 g each to prepare a sample. As H ₃ PW ₁₂ O ₄₀ , a material dissolved in water and attached to a commercially available γ-Al ₂ O ₃ ball and dried was used.
The same DME modification test and oxidation test as in Example 9 were performed on this sample.

(Example 12)
The Cu-aluminate spinel type complex oxide according to the present invention can itself be given various shapes. There are various forms of use such as pellets, honeycombs, foams, and the like, but here, a typical example is a ceramic foam. A normal ceramic sintering process can be used for the production.

CuO powder and Al ₂ O ₃ powder were weighed in equimolar amounts, mixed with an organic binder to form a slurry, and then adhered to the surface of a polyurethane sponge (foam). The ceramic-coated polyurethane foam was slowly heated to burn down the polyurethane as a skeleton by thermal decomposition (700 ° C. × 10 hours). At this time, heating was performed in an inert atmosphere such as Ar or N ₂ in order to prevent collapse due to rapid combustion. After completely burning out the polyurethane, it was transferred to an air atmosphere and subjected to main sintering at 1150 ° C. for 5 hours. The obtained sintered body was reduced at 600 ° C. for 10 minutes in a H ₂ stream to obtain a sample. The obtained sample was subjected to the same methanol reforming test and oxidation test as in Example 1.

(Example 13)
A layer serving as a precursor of γ-Al ₂ O _{3 on} the surface of a ceramic sample (before reduction) in which a spinel-type composite oxide of CuO and Al ₂ O ₃ is formed on the foam surface produced in Example 12 Was formed by a sol-gel method. This was heat-treated at 600 ° C., to obtain a catalyst precursor to form a γ-Al ₂ O ₃ phase as a solid acid on the surface. The obtained sintered body was reduced at 600 ° C. for 10 minutes in a H ₂ stream to obtain a sample. At this treatment temperature, it is considered that the phase of γ-Al ₂ O ₃ is maintained with a high specific surface area. The same DME modification test and oxidation test as in Example 9 were performed on this sample.

(Example 14)
A ceramic foam composed of alumina is immersed in an aqueous solution in which copper nitrate and aluminum nitrate are mixed in a molar ratio of 1: 2, and a Cu-Al component serving as a catalyst precursor is deposited on the surface. I let you. After drying, heat treatment was performed in an N ₂ atmosphere at 500 ° C. for 10 hours to thermally decompose the nitrate to form a mixed oxide layer of CuO and Al ₂ O _{3 on} the foam surface. Then, the catalyst precursor which baked at 1150 degreeC in air | atmosphere for 5 hours and formed the Cu-aluminate spinel type complex oxide on the ceramic foam surface was produced. Next, this was subjected to hydrogen reduction treatment at 600 ° C. for 10 minutes to deposit Cu particles on the surface.
This sample was subjected to a methanol reforming experiment and an oxidation test in the same manner as in Example 1.

(Example 15)
A layer serving as a precursor of γ-Al ₂ O ₃ was formed on the surface of the ceramic sample on which the Cu-aluminate spinel-type composite oxide layer produced in Example 14 was coated by a sol-gel method, and heat-treated at 600 ° C. Thus, a γ-Al ₂ O ₃ phase as a solid acid was formed. This was used as a catalyst precursor. This material was subjected to a reduction heat treatment in which heat treatment was performed in a hydrogen atmosphere at 600 ° C. for 10 minutes to obtain a sample.
The same DME modification test and oxidation test as in Example 9 were performed on this sample.

(Example 16)
The sintered body mainly composed of CuAl ₂ O ₄ produced in Example 1 was mechanically pulverized so as to be fine particles of about 1 μm. Using this pulverized powder, a coating layer was formed on the surface of the ceramic ceramic foam simultaneously with the alumina sol. In the same manner as in Example 15, drying, firing, and reduction heat treatment were performed to obtain a sample.
The same DME modification test and oxidation test as in Example 9 were performed on this sample.

(Example 17)
Copper nitrate hydrate and aluminum nitrate hydrate were mixed at a ratio of 1: 2 and dissolved in water to obtain an aqueous solution. The mixed aqueous solution was dried using an evaporator, and then placed in an electric furnace having an Ar atmosphere and baked at 110 ° C. for 1 hour for drying and at 500 ° C. for 10 hours for thermal decomposition treatment. Thereafter, the obtained powder was transferred to an atmospheric furnace and heat-treated at 1000 ° C. for 2 hours. Thereby, Cu—Al-based composite oxide fine particles were obtained. The fine particles were coated on a ceramic foam composed of α-Al ₂ O ₃ simultaneously with a sol containing γ-Al ₂ O ₃ . A reduction heat treatment was performed in hydrogen at 600 ° C. for 10 minutes in the same manner as in Example 15 to obtain a sample.
The same DME modification test and oxidation test as in Example 9 were performed on this sample.

The analysis results and test results of the samples of each example will be described below.
<Analysis and Test Results of Samples of Example 1, Example 2, Example 3, Comparative Example 1, and Comparative Example 2>

(Analysis result of the sample of Example 1)
As a result of X-ray diffraction, the composition of the catalyst precursor produced in Example 1 was almost identified as spinel type CuAl ₂ O ₄ and had a very small amount of CuAlO ₂ phase. The diffraction result of the X-ray diffraction of the catalyst precursor before the reduction is shown in FIG.

Cu, CuAlO ₂ and Al ₂ O ₃ phases were detected on the surface layer of the sample of Example 1 obtained by reducing the catalyst precursor at 400 ° C. The diffraction result of the X-ray diffraction of the sample after the reduction of the catalyst precursor of Example 1 is shown in FIG. In the sample of Example 1, CuAl ₂ O ₄ was not detected. At least all the CuAl ₂ O _{4 in the} surface layer portion was reduced.

A structural photograph of the catalyst obtained in Example 1 is shown in FIG. It can be seen that Cu particles having a size of several tens of nanometers are deposited on the surface portion of the ceramic with high dispersibility. Presence of particles of 200 nm or more and 5 nm or less was not confirmed. The size of the Cu particles was dispersed between about 10 nm and about 60 nm in the scanning electron microscope (SEM) observation of the sample fracture surface. The Cu particles are present in the form of being partially embedded in the ceramic substrate. This tissue property remained almost unchanged after oxidation.
The metal specific surface area by the chemical adsorption method of H ₂ gas of Example 1 was 1.2 m ² / g.

(Result of analysis of sample of Example 2)
Cu, CuAlO ₂ and Al ₂ O ₃ phases were detected on the surface layer of the sample of Example 2 obtained by reducing the catalyst precursor produced in Example 1 at 600 ° C. In the measurement of X-ray diffraction of CuAl ₂ O ₄ samples of Example 2 the presence of CuAl ₂ O ₄ was observed. The diffraction result of the X-ray diffraction of the sample after reduction of the catalyst precursor of Example 2 is shown in FIG. Compared with the material of Example 1 reduced at 400 ° C., the strength of Cu is stronger and it can be seen that precipitation is progressing. Also in the sample of Example 2, Cu particles were precipitated with high dispersibility on the surface portion of the ceramic. Presence of particles of 200 nm or more and 5 nm or less was not confirmed. The size of the Cu particles was dispersed between about 20 nm and about 80 nm in SEM observation of the sample fracture surface. The Cu particles are present in the form of being partially embedded in the ceramic substrate. This tissue property remained almost unchanged after oxidation.
The metal specific surface area by the chemical adsorption method of H ₂ gas of Example 2 was 1.5 m ² / g.

(Result of analysis of sample of Example 3)
Cu and Al ₂ O ₃ phases were respectively detected in the surface layer of the sample of Example 3 obtained by reducing the catalyst precursor produced in Example 1 at 900 ° C. The diffraction result of the X-ray diffraction of the sample after reduction of the catalyst precursor of Example 3 is shown in FIG. Even in the sample of Example 3, the presence of the CuAl ₂ O ₄ phase was not recognized. Also in the sample of Example 3, Cu particles were precipitated with high dispersibility on the surface portion of the ceramic. Presence of particles of 200 nm or more and 5 nm or less was not confirmed. The size of the Cu particles was dispersed between about 40 nm and about 120 nm in SEM observation of the sample fracture surface. The Cu particles are present in the form of being partially embedded in the ceramic substrate. This tissue property remained almost unchanged after oxidation.
The specific metal surface area of the H ₂ gas chemisorption method of Example 3 was 1.5 m ² / g.

(Analysis result of sample of Comparative Example 2)
In the surface layer of the sample of Comparative Example 2 in which the catalyst precursor produced in Example 1 was reduced at 325 ° C., Cu, CuAlO ₂ and CuAl ₂ O ₄ were detected, and the strongest in X-ray diffraction of CuAl ₂ O ₄ The diffraction intensity of the (311) plane, which is a line, was 50%, 90%, and 200% (ie more than Al ₂ O ₃ ) with respect to the strongest line diffraction intensities of Cu, CuAlO ₂ and Al ₂ O ₃ , respectively. It was. Incidentally, at a reduction temperature of 300 ° C., the presence of Cu was hardly detected by X-ray diffraction, and Cu particles could not be captured even by observation with an SEM.

(Test results of samples of Example 1, Example 2, Example 3, Comparative Example 1, and Comparative Example 2)
FIG. 6A shows the results of the first methanol reforming test on the sample of Example 1 and the results of reforming tests after multiple oxidation treatments (methanol conversion). The vertical axis indicates the percentage of methanol added to the reforming reaction with steam relative to the test temperature on the horizontal axis. In the figure, the results of the first modification test and the results of the second and fifth tests are shown. In FIG. 6A, ● corresponds to the first time, ○ corresponds to the second time, and ▲ corresponds to the fifth time.

The composition of the reformed out gas in the first methanol reforming test is shown in FIG. It can be seen that the gas produced by the reforming reaction is approximately 75% H ₂ and 25% CO ₂ . The out gas composition after the fifth reforming test was not changed at all, and the composition was almost composed of H ₂ and CO ₂ .

As is apparent from FIG. 6, almost all methanol is used for the reforming reaction at 300 ° C., and the reformed gas has an ideal performance of only H ₂ and CO ₂ . It can also be seen that this result does not decrease even after forced oxidation at 350 ° C. for 15 minutes. Rather, there is a tendency that the activity is slightly improved after oxidation (the conversion rate increases). Thereafter, it was revealed that there was no particular decrease in performance even after the oxidation-reformation test was repeated four more times (5 times in total).

In addition, when the amount ratio of CH ₃ OH and H ₂ O to be mixed was 1: 4 separately, the conversion rate increased on the lower temperature side and reached almost 100% at 250 ° C. The product gas was the same as in the case of 1: 2, and the result of only H ₂ and CO ₂ was not changed. In practical use, assuming that this reforming catalyst is used for mobile purposes in particular, it is preferable to reduce the amount of the fuel tank as much as possible. Therefore, although the conversion rate is slightly reduced, H ₂ mixed with CH ₃ OH is subsequently used. Only the results when the O amount is 1: 2 will be described.

  The sample of Example 2 showed almost the same performance as Example 1. On the other hand, in the sample of Comparative Example 2, almost no catalytic activity was observed.

FIG. 7 shows the change in weight of the spinel complex oxide CuAl ₂ O ₄ with respect to the reduction temperature in H ₂ . In the figure, it is considered that the more the value of Weight loss (%) is on the negative side, the more oxygen is released by reduction and Cu is precipitated. As is clear from this, Cu precipitation due to reduction hardly occurred at 300 ° C., and it is considered that the activity was low. In this figure, the first large weight reduction (350 to 600 ° C.) is a process in which Cu is precipitated from CuAl ₂ O ₄ to form CuAlO ₂ and Al ₂ O ₃ , and the next weight reduction (600 to 700 ° C.) is further increased. It is considered that Cu is released from CuAlO ₂ to become Al ₂ O ₃ . This also shows that it is better to raise the reduction temperature to at least 350 ° C. or higher so that Cu is sufficiently precipitated.

On the other hand, the methanol conversion of the commercially available Cu—Zn catalyst of Comparative Example 1 is shown in FIG. This material begins to reduce at a temperature of 150 ° C. or higher, and the state of Cu before reduction is in the form of CuO. A reduction temperature that is too high promotes the grain growth of Cu particles and causes a decrease in specific surface area, that is, a large decrease in activity, and is usually not raised to 250 ° C. or higher. It can be seen that the fresh sample after reduction has a very high activity, and is particularly excellent on the low temperature side. The selectivity is also high with only H ₂ and CO ₂ . However, after the oxidation, the activity decreased by about 10% in the first oxidation. As the specific surface area decreased, many aggregated particles were observed in the structure observation. Thus, it can be seen that oxidation causes a clear decrease in catalyst performance.

The result of the sample of Example 3 showed almost the same performance as that of Example 1 except that the temperature at which the methanol conversion reached 100 was slightly low and was about 280 ° C. This is considered to be due to the fact that the total amount of precipitated Cu is larger than that in Examples 1 and 2. The gas produced by the reforming reaction is approximately 75% H ₂ and 25%. It was CO _2. Further, the reforming performance after oxidation and the out gas composition were hardly changed.

Further, as a result of a shift reaction test using the material shown in Example 1, it was found that about 88% of CO was converted into CO ₂ and H ₂ at 300 ° C. In addition, even after the material is forcibly oxidized at a higher temperature of 350 ° C., it is not necessary to perform a reduction treatment, and it is reduced and regenerated with H ₂ contained in the reformed gas. It became clear to show.

<Analysis results and test results of Example 4, Example 5, Example 6, and Example 7>

(Result of analysis of sample of Example 4)
The composition of the catalyst precursor produced in Example 4 using nitrate as a starting material was identified as spinel-type CuAl ₂ O ₄ as in Example 2 as a result of X-ray diffraction, and a very small amount of CuAlO ₂ phase. It was what had.

On the other hand, Cu, CuAlO ₂ and Al ₂ O ₃ phases were detected on the surface layer of the sample of Example 4 in which the catalyst precursor was reduced. However, the CuAl ₂ O ₄ phase was not detected in the sample of Example 4. Also in the sample of Example 4, Cu particles were precipitated with high dispersibility on the surface portion of the ceramic. Presence of particles of 200 nm or more and 5 nm or less was not confirmed. The size of the Cu particles was dispersed between about 10 nm and 60 nm in SEM observation of the sample fracture surface. The Cu particles are present in the form of being partially embedded in the ceramic substrate. This tissue property remained almost unchanged after oxidation. In Example 4 using nitrate as a starting material, densification of the material was observed even at the same sintering temperature as compared with the sample of Example 1.

(Result of analysis of sample of Example 5)
As a result of X-ray diffraction, the composition of the catalyst precursor produced in Example 5 was identified as approximately CuAl ₂ O ₄ . A CuAlO ₂ phase was not detected in the sample to which TiO ₂ was added.
On the other hand, Cu, CuAlO ₂ and Al ₂ O ₃ phases were detected on the surface of the sample of Example 5 in which the catalyst precursor was reduced.

In the sample of Example 5, as in Example 2, the CuAl ₂ O ₄ phase was not detected. Also in the sample of Example 5, Cu particles were precipitated with high dispersibility on the surface portion of the ceramic. Presence of particles of 200 nm or more and 5 nm or less was not confirmed. The size of the Cu particles was dispersed between about 20 nm and 60 nm in SEM observation of the sample fracture surface. The Cu particles are present in the form of being partially embedded in the ceramic substrate. This tissue property remained almost unchanged after oxidation.

(Result of analysis of sample of Example 6)
As a result of X-ray diffraction, the composition of the catalyst precursor produced in Example 6 was identified as CuAl ₂ O ₄ , CuAlO ₂ and ZnO as main components.

On the other hand, Cu, ZnO, CuAlO ₂ and Al ₂ O ₃ were detected in the surface layer of the sample of Example 6 in which the catalyst precursor was reduced.

The presence of CuAl ₂ O ₄ was not observed in the X-ray diffraction measurement of the sample of Example 6 after reduction. Also in the sample of Example 6, Cu particles were precipitated with high dispersibility on the surface portion of the ceramic. Presence of particles of 200 nm or more and 5 nm or less was not confirmed. The size of the Cu particles was dispersed between about 20 nm and 60 nm in SEM observation of the sample fracture surface. The Cu particles are present in the form of being partially embedded in the ceramic substrate. This tissue property remained almost unchanged after oxidation.

(Result of analysis of sample of Example 7)
As a result of X-ray diffraction, the composition of the catalyst precursor produced in Example 7 was almost identified as CuAl ₂ O ₄ and ZnO.

On the other hand, Cu, ZnO, CuAlO ₂ and Al ₂ O ₃ were detected in the surface layer of the sample of Example 7 in which the catalyst precursor was reduced.

The presence of CuAl ₂ O ₄ was not observed in the measurement by X-ray diffraction after reduction of the sample of Example 7. Also in the sample of Example 7, Cu particles were precipitated with high dispersibility on the surface portion of the ceramic. Presence of particles of 200 nm or more and 5 nm or less was not confirmed. The size of the Cu particles was dispersed between about 20 nm and 60 nm in SEM observation of the sample fracture surface. Cu particles existed in the form of being partially embedded in the ceramic substrate. This tissue property remained almost unchanged after oxidation.

(Test results of samples of Example 4, Example 5, Example 6, and Example 7)
The methanol reforming performance of the sample of Example 4 was almost the same as that shown in Example 1. It has been found that the mechanical strength of the catalyst is increased in that it is denser, and this material is particularly effective when the material itself is used as a monolith catalyst.

As shown in Example 5, such an effect of promoting densification remarkably appeared even when a small amount of TiO ₂ was added. Sintered body by adding sintering of TiO ₂ is greater shrinkage, density, for example, was fired only CuO powder and _Al 2 _{O 3} powder without adding TiO ₂ when added to TiO ₂ 0.6% by weight Compared with that, it became about 1.5 times. It was found that the Ti component added in a small amount hardly changes the reforming performance of methanol. However, it has also been clarified that when the Ti component is introduced in an appropriate amount or more, the reforming temperature shifts to the high temperature side. It can be seen that the addition of a small amount of Ti component is effective in improving the mechanical strength of the material without degrading the catalyst performance.

Further, the sample obtained by reducing the catalyst precursor to which the Zn component was added in Example 6 at 600 ° C. had a structure in which Cu particles were isolated and dispersed on the substrate, as shown in FIG. Although the Cu content is reduced with respect to the same amount of catalyst by the addition of the Zn component, the activity at a low temperature and the high selectivity (almost H ₂ as seen in a general Cu—Zn-based catalyst). And CO ₂ only) were observed. In addition to exhibiting low-temperature activity close to that of commercially available materials, Cu particles were dispersed and precipitated, so no performance degradation was observed even when oxidized.

  Similarly, in Example 7 in which a Zn component and a small amount of Ti component were added simultaneously, high activity in methanol reforming and durability against oxidation were confirmed. Moreover, this Ti additive has a high density, and it is considered that stable strength can be expressed even if the catalyst itself is made into a monolith.

In addition, as a result of performing a shift test on the sample of Example 5 prepared by adding the Ti component, about 88% of CO is converted to CO ₂ and H ₂ at 300 ° C., as in the sample of Example 1. I understood. In addition, even after the material is forcibly oxidized at a higher temperature of 350 ° C., it is not necessary to perform a reduction treatment, and it is reduced and regenerated with H ₂ contained in the reformed gas. It became clear to show. This has revealed that it is possible to provide a material that is advantageous not only in terms of catalyst performance but also in terms of mechanical properties.

The analysis results of each sample are described below.
(Analysis result of sample of Example 8 and Comparative Example 3)
As a result of X-ray diffraction, it was confirmed that the composition of the catalyst precursor produced in Example 8 was almost a mixed phase of CuAl ₂ O ₄ and CoAl ₂ O ₄ .

On the other hand, Cu, Co, and Al ₂ O ₃ were detected on the surface layer of the sample obtained by reducing the catalyst precursor, and CuAl ₂ O ₄ and CoAl ₂ O ₄ were not detected at all.
Also in the sample of Example 8, Cu particles were precipitated with high dispersibility on the surface portion of the ceramic. Presence of particles of 200 nm or more and 5 nm or less was not confirmed. Presence of particles of 200 nm or more and 5 nm or less was not confirmed. The size of the Cu and Co particles was dispersed between about 30 nm and about 80 nm in SEM observation of the sample fracture surface. Cu particles and Co particles are present in the form of being semi-embedded in the ceramic substrate. This tissue property remained almost unchanged after oxidation.

  On the other hand, in the sample of Comparative Example 3, Co particles were precipitated, but naturally there was no precipitation of Cu particles.

(Test results of samples of Example 8 and Comparative Example 3)
FIG. 9 shows the weight change of the mixture of the catalyst precursor, spinel-type composite oxide CuAl ₂ O ₄ , and CoAl ₂ O ₄ in Example 8 with respect to the reduction temperature in H ₂ . In the figure, it is considered that CuAl ₂ O ₄ and CoAl ₂ O ₄ decrease as the value of Weight loss (%) is on the negative side, and metal Cu and metal Co are precipitated instead. As can be seen from the comparison with FIG. 7, it can be seen that the deposition temperature of metal Cu is shifted to the high temperature side due to the simultaneous presence of Cu and Co. It is considered that the precipitation of both begins at around 750 ° C. In fact, the composition of the sample reduced at 900 ° C. was Cu, Co and Al ₂ O ₃ . The shift performance before oxidation of this material was the same as that in the case of using only CoO of Comparative Example 3, that is, the most active at 350 ° C. and the CO conversion was 93%. The optimum use temperature of the catalyst containing Co as a main component is about 50 ° C. higher than that of the Cu-based catalyst.
In addition, performance that hardly changed even after 350 ° C. oxidation was obtained (maximum at 350 ° C., CO conversion rate 94%). In this case, since the reduction treatment is not particularly performed after the oxidation, it is considered that the material was reduced and regenerated by H ₂ contained in the reformed gas at a use temperature of 350 ° C., similarly to the Cu system.

On the other hand, in the case of the catalyst having only Co as the precipitated particles shown in Comparative Example 3, no reaction occurred at the test temperature of 350 ° C. after the oxidation. This is because, in another experiment, in the case of a Co-based catalyst, when the reducing gas contains CO ₂ at a relatively high concentration, the reduction becomes difficult, and the temperature is about 600 ° C. until the reduction is sufficiently performed. It is clear that is necessary. However, as in Example 8, it was found that if a small amount of Cu was present simultaneously with Co, it was sufficiently reduced at 350 ° C. even if CO ₂ was contained.

In addition, in an experiment using this oxidized material as a reforming catalyst for methanol, immediately after the introduction of CH ₃ OH and H ₂ O as fuels at around 200 ° C., even though no reduction treatment was performed. A reforming reaction occurred. It first generates and H ₂ react with Cu component easily fuel slightly present in the substrate surface catalyst, Co particles is considered that were being reduced one after another by the H _2. Thus, it was clarified that the Co ₃ O ₄ phase on the Co surface formed by oxidation is easily reduced by the presence of Cu and can be regenerated.

<Test Results of Sample of Example 9>
FIG. 10 shows the result of the DME reforming experiment (conversion rate with respect to the reforming temperature) using the mixture of γ-Al ₂ O ₃ and the catalyst prepared in Example 1. The conversion was 60% at 300 ° C and 94% at 350 ° C. Considering that the H ₂ O flow rate is as low as 1: 4 with respect to the DME flow rate, this performance is good. Further, the concentration of the produced CO gas was suppressed to about 1% at 350 ° C. This material was taken out into the atmosphere and then a modification experiment was performed again, which showed exactly the same performance.

As described above, the Cu / Al ₂ O ₃ based material produced by the reduction precipitation method has the characteristics that it is active and excellent in selectivity at low temperatures with respect to methanol reforming and can be easily regenerated even when oxidized. . Since the generated gas is almost only H ₂ and CO ₂ and the CO concentration is sufficiently lower than 1%, there is a possibility that the shift catalyst in the latter stage is unnecessary.

  It was also revealed that a small amount of Cu was simultaneously deposited in the Co-based catalyst to promote Co reduction and to be regenerated at a low temperature.

Furthermore, it has been shown that, as a reforming catalyst for dimethyl ether (DME), which is also useful for mobile use, a significant effect can be exhibited by applying it simultaneously with γ-Al ₂ O ₃ .

<Test Results of Sample of Example 10>
The combination of the zeolite solid acid catalyst and the sample of Example 1 showed activity at a lower temperature in the DME reforming test with the combination of γ-Al ₂ O ₃ shown in Example 9 and the catalyst prepared in Example 1. . The conversion reached 95% at 300 ° C. Further, it was found that the concentration of produced CO gas can be suppressed to about 1% at 350 ° C. However, in the case of a zeolitic material, it was found that it is preferable to use it at a temperature lower than this because generation of CH ₄ becomes remarkable at a high temperature of 350 ° C. or higher.

<Test result of sample of Example 11>
The combination of phosphorus-tungsten oxide (H ₃ PW ₁₂ O ₄₀ ), one of the heteropolyacids, and the sample of Example 1 showed activity on the lower temperature side. The conversion rate in the DME reforming test was 90% at 300 ° C. Further, it was found that the concentration of produced CO gas can be suppressed to about 1% at 350 ° C.

<Analysis results and test results of sample of Example 12>
As one embodiment according to the present invention, the catalyst precursor itself was formed in a foam shape. As a result of identification of the constituent phases by X-ray diffraction, it was found that the catalyst precursor contains CuAl ₂ O ₄ as a main component and contains a small amount of CuAlO ₂ . The constituent phases of the material obtained by hydrogen reduction were Cu, CuAlO ₂ and Al ₂ O ₃ , and no CuAl ₂ O ₄ phase was detected. That is, a ceramic foam composed of a composite phase of CuAlO ₂ and Al ₂ O ₃ was used as a skeleton, and Cu was deposited on the surface thereof. Presence of particles of 200 nm or more and 5 nm or less was not confirmed. The size of the Cu particles was dispersed between about 20 nm and about 80 nm in SEM observation of the sample fracture surface.

As a result of a methanol reforming test using this material, the conversion rate reached 100% at 300 ° C. as in the result of Example 1, and the reformed gas composition was ideal performance consisting of only H ₂ and CO _2. showed that. This material was taken out into the atmosphere and then a reforming experiment was performed again, which showed almost the same performance. It was also found that the pressure loss when the flow rate was increased was very small. This also indicates that even if the material is formed in a honeycomb shape, it can be effectively modified with little pressure loss. It is the characteristic of the base-material integrated catalyst by this invention.

<Analysis Results and Test Results of Sample of Example 13>
As a result of identification of the constituent phase by X-ray diffraction, at least the surface portion of the produced ceramic (catalyst precursor) was composed of γ-Al ₂ O ₃ , CuAl ₂ O ₄ and CuAlO ₂ . This was reduced, the sample was precipitated Cu is, _Cu, is composed of CuAlO 2, _Al 2 _{O 3} and _{γ-Al 2 O 3, CuAl} 2 O 4 phase was not detected. Presence of particles of 200 nm or more and 5 nm or less was not confirmed. The size of the Cu particles was dispersed between about 20 nm and about 80 nm in SEM observation of the sample fracture surface.

This sample was subjected to a DME reforming experiment. As a result, the conversion rate was 65% at 300 ° C and 95% at 350 ° C. Further, almost no CO gas concentration was detected, and good performance was obtained. The production of CH ₄ gas was 0 within the test range.

<Analysis Results and Test Results of Sample of Example 14>
The composition of the catalyst precursor layer formed on the surface of the ceramic foam having α-Al ₂ O ₃ as a skeleton is, as a result of measurement by X-ray diffraction, containing CuAl ₂ O ₄ as a main component and a small amount of CuAlO _2. It became clear. And Cu components which were reduced to, is constituted by CuAlO ₂ and _{Al 2 O 3, CuAl 2 O} 4 phase was not detected. Presence of particles of 200 nm or more and 5 nm or less was not confirmed. The size of the Cu particles was dispersed between about 20 nm and 60 nm in SEM observation of the sample fracture surface.

As a result of a methanol reforming test using this material, it was found that the conversion rate was 100% at 300 ° C., and the reforming performance was almost the same as that shown in Example 12. The product gas also showed characteristics of approximately 75% H ₂ , 25% CO ₂ and a Cu-based catalyst. Further, the reforming performance after oxidation and the out gas composition were hardly changed.

<Analysis results and test results of Example 15>
In the measurement of the constituent phase of the catalyst precursor by X-ray diffraction, γ-Al ₂ O ₃ , CuAl ₂ O ₄ and CuAlO ₂ were identified. This those reduction, the _{γ-Al 2 O 3, Cu} , In CuAlO ₂ and _Al 2 _{O 3,} the CuAl ₂ O ₄ phase was not detected. Presence of particles of 200 nm or more and 5 nm or less was not confirmed. The size of the Cu particles was dispersed between about 20 nm and 60 nm in SEM observation of the sample fracture surface.

As a result of the DME reforming test using this, the conversion rate was 64% at 300 ° C and 94% at 350 ° C. Further, almost no CO gas concentration was detected, and good performance was obtained. The production of CH ₄ gas was 0 within the test range.

<The analysis result and test result of Example 16>
As a result of identification of the constituent phase by X-ray diffraction, the surface of the alumina foam, which is a skeleton, covers particles composed of CuAl ₂ O ₄ and CuAlO ₂ that are the same catalyst precursors as those prepared in Example 1, and covers the particles. Thus, a phase of γ-Al ₂ O ₃ formed was confirmed. When this material was reduced, about 1 μm-sized composite oxide particles (CuAlO ₂₎ having γ-Al ₂ O ₃ on the alumina foam substrate and Cu particles precipitated and dispersed in a size of about 20 nm to 60 nm on the surface. And Al ₂ O ₃ ). Presence of particles of 200 nm or more and 5 nm or less was not confirmed. As a constituent phase of the composite oxide particles, CuAl ₂ O ₄ was not detected.

As a result of the DME reforming test using this, a conversion rate of 65% at 300 ° C. and 95% at 350 ° C. was obtained. Further, the generated CO gas concentration was hardly detected as 1% or less, and good performance was obtained. The production of CH ₄ gas was 0 within the test range.

<Analysis results and test results of Example 17>
As a result of identification of the constituent phase by X-ray diffraction, the surface of the alumina foam as the skeleton is covered with fine particles composed of CuAl ₂ O ₄ and CuAlO ₂ which are the same catalyst precursors as those prepared in Example 1 and covered therewith. Thus, a phase of γ-Al ₂ O ₃ formed was confirmed. When this material was reduced, composite oxide particles (CuAlO ₂ and Al) having a size of several tens of nm having γ-Al ₂ O ₃ on the alumina foam substrate and Cu particles deposited on the surface with a size of about 20 nm to 60 nm. ₂ O ₃ ) was simultaneously supported. Presence of Cu particles of 200 nm or more and 5 nm or less was not confirmed. As a constituent phase of the composite oxide particles, CuAl ₂ O ₄ was not detected.

As a result of the DME reforming test using this, a conversion rate of 65% at 300 ° C. and 95% at 350 ° C. was obtained. Further, the generated CO gas concentration was hardly detected as 1% or less, and good performance was obtained. The production of CH ₄ gas was 0 within the test range.

The schematic diagram which shows the hydrocarbon fuel reformer concerning one Embodiment. The schematic diagram which shows the catalyst produced in the honeycomb form concerning one Embodiment. 1 is a cross-sectional view of a honeycomb-shaped catalyst according to an embodiment. Schematic which shows the experimental apparatus for the reformability evaluation concerning an Example. FIG. 3 is a structural diagram of a catalyst sample obtained in Example 2. FIG. 6 is a characteristic diagram showing the methanol reforming test result of the catalyst sample obtained in Example 1. Characteristic diagram showing the weight change with respect to the reduction temperature in the spinel composite oxide CuAl ₂ O ₄ in _{H 2.} The characteristic view which shows the methanol reforming test result of the catalyst sample of Comparative Example 1. Characteristic diagram showing the weight change with respect to the reduction temperature in in _{H 2} a mixture of spinel-type complex oxide _{CuAl 2 O 4, CoAl 2 O} 4. Characteristic diagram showing the conversion over reforming temperature in the reforming experiments DME using a mixture of catalyst and γ-Al ₂ O ₃ prepared in Example 9. The characteristic view which shows the diffraction result of the X-ray diffraction before the reduction | restoration of the catalyst precursor of Example 1. FIG. The characteristic view which shows the diffraction result of the X-ray diffraction after the reduction | restoration of the catalyst precursor of Example 1. FIG. The characteristic view which shows the diffraction result of the X-ray diffraction after the reduction | restoration of the catalyst precursor of Example 2. FIG. The characteristic view which shows the diffraction result of the X-ray diffraction after the reduction | restoration of the catalyst precursor of Example 3. FIG.

Explanation of symbols

DESCRIPTION OF SYMBOLS 10 ... Tank 20 ... Modifier tank 30, 40 ... Preheating apparatus 50 ... Mixer 60 ... Container 70 ... Burner 80 ... Reforming catalyst layer 90 ... Metal particle 100 ... honeycomb inner wall 110 ... catalyst

Claims (20)

A catalyst obtained by reducing a catalyst precursor using a Cu-aluminate spinel composite oxide,
At least the surface layer portion contains Al ₂ O ₃ and the diffraction intensity of the (311) plane, which is the strongest line in the X-ray diffraction of the spinel-type composite oxide CuAl ₂ O ₄ , is CuAlO ₂ or Al ₂ O ₃ . A catalyst comprising at least one kind, an oxide that is 5% or less of the strongest line diffraction intensity of Cu, and metal Cu particles embedded and dispersed in the oxide.   The catalyst according to claim 1, wherein the oxide contains Ti.   The catalyst according to claim 1, wherein the oxide contains Zn.   A catalyst comprising the catalyst according to claim 1 and a solid acid catalyst.   A catalyst according to claim 1 or 4, a carrier for supporting the catalyst, and a container for storing a carrier for supporting the catalyst, and the fuel and water vapor supplied from the outside are contained in the container. A reformer characterized in that hydrogen is extracted from the reaction product by reacting in the reactor. A fuel cell;
A reformer according to claim 5;
A fuel cell system comprising: a hydrogen supply path for supplying hydrogen taken out by the reformer to the fuel cell.   A method for producing a catalyst, comprising subjecting a catalyst precursor of a Cu-aluminate spinel composite oxide to a reduction heat treatment at a temperature of 350 ° C. or higher and 1000 ° C. or lower.   The method for producing a catalyst according to claim 7, wherein the catalyst precursor is a sintered body obtained by firing a mixture of an aluminum compound and a copper compound at a temperature of 700 ° C to 1300 ° C. .   8. The catalyst precursor is a sintered body obtained by firing a mixture of an aluminum compound, a copper compound, and a titanium compound at a temperature of 700 ° C. or higher and 1300 ° C. or lower. A method for producing the catalyst.   The method for producing a catalyst according to claim 9, wherein the catalyst precursor contains 0.01 to 2 wt% of titanium in terms of metal.   8. The catalyst precursor is a sintered body obtained by firing a mixture of an aluminum compound, a copper compound, and a zinc compound at a temperature of 700 ° C. or higher and 1300 ° C. or lower. A method for producing the catalyst.   The method for producing a catalyst according to claim 11, wherein zinc is contained in the catalyst precursor in an amount of 10 wt% to 50 wt% in terms of metal. A catalyst obtained by reducing a catalyst precursor using a Cu-aluminate spinel type composite oxide and a Co-aluminate spinel oxide,
At least the surface layer portion contains Al ₂ O ₃ and the diffraction intensity of the (311) plane which is the strongest line in the X-ray diffraction of the spinel-type composite oxide CuAl ₂ O ₄ is that of CuAlO ₂ and Al ₂ O ₃ At least one kind, an oxide that is 5% or less with respect to the strongest line diffraction intensity of each of Cu, metal Cu particles embedded and dispersed in the oxide, and metal Co particles embedded and dispersed in the oxide And a catalyst.   The catalyst according to claim 13, wherein the content of metal Cu with respect to metal Co is 0.01 mol% or more and 5 mol% or less.   A catalyst comprising the catalyst according to claim 13 and a solid acid catalyst.   A catalyst according to claim 13 or 15, a carrier for supporting the catalyst, and a container for storing a carrier for supporting the catalyst, wherein the fuel and water vapor supplied from the outside are contained in the container. A reformer characterized in that hydrogen is extracted from the reaction product by reacting in the reactor. A fuel cell;
A reformer according to claim 16;
A fuel cell system comprising: a hydrogen supply path for supplying hydrogen taken out by the reformer to the fuel cell.   A method for producing a catalyst, comprising subjecting a catalyst precursor using a Cu-aluminate spinel-type composite oxide and a Co-aluminate spinel-type composite oxide to a reduction heat treatment at a temperature of 600 ° C to 1000 ° C.   19. The catalyst precursor is a sintered body obtained by firing a mixture of an aluminum compound, a copper compound, and a cobalt compound at a temperature of 700 ° C. or higher and 1300 ° C. or lower. A method for producing the catalyst.   The method for producing a catalyst according to claim 19, wherein the catalyst precursor has a Cu content with respect to Co of 0.01 mol% or more and 5 mol% or less.