JP2005125137A - Monolithic catalyst for shift reaction - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To obtain a monolithic catalyst having excellent activity in a shift reaction. <P>SOLUTION: This monolithic catalyst is used for the shift reaction of a carbon monoxide-containing gas of ≤0.01 vol.% O<SB>2</SB>concentration and contains metal platinum. The catalyst has on a monolithic carrier a shift reaction catalyst layer which does not contain Mn, Fe, Co or Cu and an upper layer which is formed on the shift reaction catalyst layer and contains at least one or more elements selected from Mn, Fe, Co and Cu. The oxidation reaction of CO into CO<SB>2</SB>is promoted and the removal rate of CO is improved by arranging the upper layer containing such the elements. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention is a monolithic catalyst for shift reaction, on a monolith support, a shift reaction catalyst layer not containing any element of Mn, Fe, Co or Cu, and Mn, Fe, Co, The present invention relates to a monolith catalyst for shift reaction having an upper layer containing one or more elements selected from Cu and having excellent shift reaction activity.

Fuel cells use pure hydrogen as a fuel source, but at this stage, in consideration of safety, infrastructure, etc., methanol, natural gas, gasoline, etc. are used as a fuel source and these are reformed and produced as a by-product CO is removed by a shift reaction or a CO removal reaction to finally obtain high-purity H ₂ gas. Here, the shift reaction is a reaction in which water vapor is brought into contact as shown in the following formula, and finally converted into carbon dioxide and hydrogen. For this reason, it may be called an aquatic shift reaction.

  Conventionally, Cu catalysts such as Cu / Zn-based catalysts, Cu / Zn / Al-based catalysts, and Cu / Cr-based catalysts have been used for the shift reaction. In this case, the amount of water vapor necessary for reducing CO by the shift reaction also increases at the same time, so that the water vapor supplied to the reaction cannot be sufficiently supplied, and the shift reaction may not proceed. .

A shift reaction catalyst provided with a water vapor adsorbing substance capable of adsorbing water vapor in the catalyst has been disclosed for the purpose of compensating for such a shortage of water vapor and promoting the shift reaction (Patent Document 1). The water vapor adsorbing substance disposed in the shift reaction catalyst described in the above publication has an equilibrium state in which water vapor is not substantially exchanged with the surroundings under predetermined conditions, and the water vapor partial pressure of the surroundings is An adsorption state in which water vapor is adsorbed when it is higher than the surrounding water vapor partial pressure in the equilibrium state, and a release state in which water vapor is released when the surrounding water vapor partial pressure is lower than the surrounding water vapor partial pressure in the equilibrium state. The water vapor is released when the partial pressure of water vapor in the gas subjected to the shift reaction is lower than the surrounding water vapor partial pressure in the equilibrium state, and the shift reaction can proceed using this water vapor. . Therefore, even when the amount of water vapor used for the shift reaction is insufficient, it is possible to suppress a decrease in activity of the shift reaction due to the shortage of water vapor. In this publication, the water vapor-adsorbing substance is preferably formed to be porous, and zeolite is particularly preferably used. By using a porous material, carbon monoxide and water vapor in the gas used for the shift reaction can be easily diffused in the water vapor adsorption part formed in the porous material, and the supply of water vapor to the catalyst metal can proceed smoothly. This is to make it happen.
JP 2002-066326 A

  However, although the method described in Patent Document 1 is characterized in that a water vapor adsorption layer is provided, it is not sufficient to ensure water vapor for promoting the shift reaction.

In the shift reaction in which water vapor is supplied to CO and converted into CO ₂ and H ₂ by the new technology, the present invention is stable even when the concentration of CO in the gas used for the shift reaction changes. An object of the present invention is to provide a highly active monolith catalyst for shift reaction that can convert this into CO ₂ .

  In particular, it is an object of the present invention to provide a monolithic catalyst for shift reaction that can be used for a fuel reforming fuel cell vehicle or the like in which a mounting space is limited by stably maintaining high catalyst activity.

As a result of examining the reaction mechanism of the shift catalyst in detail, the present inventor supports the shift reaction catalyst on the monolith support, and further laminates an upper layer containing a specific element on the monolith carrier, from the CO to CO ₂ in the upper layer. Conversion can be promoted, and particularly when the upper layer has hydrocarbon selective oxidation characteristics and CO selective oxidation characteristics, the effect is excellent, and this effect is effective even when the noble metal is not included in the upper layer, Further, when such an upper layer is laminated, the CO concentration in the upper layer portion is lowered, so that the shift reaction catalyst layer in the lower layer becomes a reducing atmosphere, thereby promoting the reaction in which H ₂ O is decomposed into H ₂ and O. Rukoto, particularly increased oxygen transfer capacity if the like shifts metal oxides with redox ability to catalyst layers, provided the O by decomposition of H _{2 O} as a whole monolithic catalyst If, it found that the reaction of the CO ₂ by binding of CO and O can be very efficiently promoted, and completed the present invention.

According to the present invention, a carbon monoxide-containing gas having an O ₂ concentration of 0.01% by volume or less is formed by laminating a layer containing one or more elements selected from Mn, Fe, Co, and Cu on a monolith support. Even when converting to CO ₂ by a shift reaction, a monolith catalyst for shift reaction having an excellent CO removal rate can be obtained.

  Moreover, heat resistance can be ensured and shift reaction activity can be improved by arranging a shift reaction catalyst layer containing elements such as aluminum and zirconium.

  The monolith catalyst for shift reaction of the present invention has high activity, and therefore can be sufficiently used for vehicles having a limited mounting volume.

The first of the present invention is a platinum metal-containing monolith catalyst used for a shift reaction of a carbon monoxide-containing gas having an O ₂ concentration of 0.01% by volume or less, and contains Mn, Fe, Co, or Cu on the monolith support. A shift reaction catalyst layer, and an upper layer containing at least one element selected from Mn, Fe, Co, and Cu stacked thereon.

The shift reaction catalyst promotes a reaction for converting CO into CO ₂ , and therefore an oxygen atom bonded to CO is essential. In order to provide this oxygen atom, H ₂ O is supplied, which is decomposed into hydrogen gas and oxygen atoms, and the obtained active oxygen is used. In the present invention, the oxidation activity from CO to CO ₂ is improved by laminating a layer containing at least one element selected from Mn, Fe, Co, and Cu on the upper part of the shift reaction catalyst layer. Promote shift reaction. Therefore, in the present invention, O ₂ concentration in the gas to be provided to the shift reaction can be carried out efficiently shift reaction even when the low concentration of 0.01% by volume or less. Hereinafter, the present invention will be described in detail.

A feature of the present invention resides in that a layer containing one or more elements selected from Mn, Fe, Co, and Cu is laminated on a monolith support. When the element is present, the oxidation reaction can be activated and the conversion from CO to CO ₂ can be promoted. Examples of these supply sources include oxides, nitrates, sulfates, halides, hydroxides, ammonium salts, and acetates. In particular, nitrates such as manganese nitrate, iron nitrate, cobalt nitrate, and copper nitrate are preferably used. In order to coat these elements on a monolith support, a compound containing the above elements is dissolved or dispersed in a coating aid such as alumina sol, and the elements contained in the upper layer after completion or the total concentration of the elements are What is necessary is just to apply | coat and dry so that it may become the range of 0.001-5 mass%. As a form in the shift reaction monolith catalyst of one or more elements selected from Mn, Fe, Co, and Cu described above, it is generally present in the form of an oxide because the monolith catalyst is calcined and completed. However, it is not particularly limited to oxides, and any form may be used.

The upper layer described above preferably has a hydrocarbon selective oxidation function or a CO selective oxidation function. Thus, a hydrocarbon selective oxidation function and a CO selective oxidation function can be provided, and conversion of CO to CO ₂ is promoted by these actions, and the CO concentration is reduced. The upper layer may further contain a noble metal and a metal oxide. This is because oxygen atoms necessary for the conversion from CO to CO ₂ can be preferentially supplied, and as a result, the shift activity can be improved.

  As a noble metal that can be used for imparting a hydrocarbon selective oxidation function and a CO selective oxidation function and improving the CO removal ability, at least one kind of noble metal element selected from platinum, rhodium, palladium, ruthenium, iridium and osmium is used. There is. The supply source of these elements is not particularly limited, and compounds containing these elements can be widely used. For example, nitrates, sulfates, ammonium salts, amines, carbonates, bicarbonates, halogen salts, nitrites, inorganic salts such as oxalic acid, carboxylates and hydroxides such as formates, alkoxides, oxides And can be selected as appropriate depending on the type and pH of the solvent in which these are dissolved. Among these, nitrates, carbonates, oxides, hydroxides, acetates and the like are preferable for industrial use.

  The concentration of the noble metal contained in the upper layer is preferably 0 to 20% by mass, more preferably 0.01 to 20% by mass, and particularly preferably 0.1 to 15% by mass. When it exceeds 20 mass%, the compounding quantity of 1 or more types of elements chosen from Mn, Fe, Co, and Cu will fall, and the CO removal rate improvement effect may not be exhibited. These noble metals are considered to be active components of the catalyst, and by addition, the contact rate with CO is controlled even at low temperatures, and the CO removal rate can be improved. In the present invention, it is preferable that platinum element is contained particularly in terms of excellent CO removal rate.

  On the other hand, as one of the features of the present invention, the upper layer may not contain a noble metal. As described in the examples described later, even when the noble metal is not included in the upper layer, the oxidation activity is improved by including one or more elements selected from Mn, Fe, Co, and Cu, It has been found that the shift reaction can be substantially accelerated.

In addition, there are no particular limitations on the metal oxide that can be used to improve the CO removal ability in order to provide a hydrocarbon selective oxidation function and a CO selective oxidation function, but preferably vanadium, titanium, tungsten, indium There is an oxide containing one or more selected from the group consisting of cerium, praseodymium, samarium, ytterbium or neodymium. These may be composite oxides containing two or more elements or other elements than the above. In the present invention, the term “oxide” includes composite oxides. In the present invention, an oxide containing cerium and / or titanium is particularly preferable. When titanium is included, the effect of decomposing H ₂ O to obtain O is excellent. In addition, when cerium is included, the oxygen carrying ability is improved because the carrying ability of active oxygen is excellent.

Examples of such metal oxides include phosphors such as CeO ₂ , PrO ₂ , ThO ₂ , PaO ₂ , ZrO ₂ , and PuO _{2 represented} by the AX ₂ type when the cations are A and B and the anion is X. There are stone type, rutile type such as TiO ₂ , GeO ₂ , IrO ₂ , RuO ₂ , and anatase type TiO ₂ . Further, CaTiO ₃ represented by _{ABX 2, SrTiO 3, BaTiO 3} , CdTiO 3, CdTiO 3, PbTiO 3, CaCeO 3, SrCeO 3, BaCeO 3, CdCeO 3, PbCeO 3, NaNbO 3, KNbO 3, NaWO 3, CaZrO Perovskite type complex oxides which are complex oxides containing lattice defect oxygen such as ₃ , SrZrO ₃ , BaZrO ₃ , PbZrO ₃ , CaSnO ₃ , SrSnO ₃ , ZrCeO ₃ can also be preferably used. Further, as such a complex oxide containing lattice defect oxygen, for example, a perovskite complex oxide described in JP-A-11-165070 may be used. Preferred is a composite oxide containing a base metal and a rare earth metal in addition to a platinum group metal, wherein the platinum group metal is palladium and ruthenium, the base metal is copper, and the rare earth metal is cerium and / or neodymium. A so-called perovskite complex oxide represented by xCux (PM) yOz can be exemplified. Ce1-xCux (PM) yOz is prepared by mixing nitrates and / or hydrochlorides of each metal in a predetermined stoichiometric ratio and adding them to a sodium octylate solution to synthesize an octylate compound, and then drying at low temperature. And can be obtained by firing in air. In the present invention, it is particularly preferable to use a complex oxide containing lattice defect oxygen.

The source of such metal oxide elements is not particularly limited, and compounds containing these elements can be widely used. Such compounds include nitrates, sulfates, ammonium salts, amines, carbonates, bicarbonates, halogen salts, nitrites, inorganic salts such as oxalic acid, carboxylates and hydroxides such as formate, Examples include alkoxides and oxides, which can be appropriately selected depending on the type and pH of the solvent in which these are dissolved. Among these, nitrates, carbonates, oxides, hydroxides and the like are preferable for industrial use. When these oxides and composite oxides are blended in the present invention, oxygen atoms necessary for the conversion from CO to CO ₂ can be preferentially supplied, and as a result, the CO removal rate can be improved.

Moreover, it is preferable that the BET specific surface area of the said metal oxide is 40 m < ² > / g or more, More preferably, it is 60 m < ² > / g or more.

In the monolith catalyst for shift reaction of the present invention, the shift reaction catalyst layer and the upper layer may be laminated on the monolith support. Therefore, another layer may be formed between the shift reaction catalyst and the upper layer, between the monolith support and the shift reaction catalyst layer, and further above the upper layer. However, in the present invention, it is preferable that the shift reaction catalyst and the upper layer are adjacent to each other, and it is particularly preferable that the upper layer is laminated adjacent to the surface layer of the monolith catalyst. When the upper layer contains one or more selected from Mn, Fe, Co, and Cu, the conversion from CO to CO ₂ can proceed, and when the shift reaction catalyst layer is adjacent, the CO concentration in the upper layer This is because since the catalyst layer becomes a reducing atmosphere as the temperature decreases, the decomposition of H ₂ O into H ₂ and O is accelerated quickly, and the oxygen supply capability is improved.

  In the present invention, the shift reaction catalyst layer does not contain Mn, Fe, Co and Cu. This is to clarify the functional differentiation between the upper layer and the shift reaction catalyst layer and promote the effect of the present invention. On the other hand, in order to perform a shift reaction, it is preferable to contain a noble metal and a metal oxide having oxidation-reduction ability.

As the noble metal used at this time, a noble metal that can be blended in the above-described upper layer can be used. Under the present circumstances, it is preferable that the noble metal concentration contained in a lower layer is 0.01-20 mass%, More preferably, it is 0.1-15 mass%, Most preferably, it is 0.5-10 mass%. If it is less than 0.01% by mass, the CO removal rate may not be sufficient. These elements are considered to be active components of the catalyst, and the contact rate with CO can be improved even at a low temperature to improve the CO removal rate. In the present invention, it is preferable that platinum element is contained particularly in terms of excellent CO removal rate. In addition,
In the present invention, the average amount of noble metal contained in the shift reaction catalyst layer is 0.1 to 20 g, more preferably 1.0 to 15 g, per liter of the packed portion. If the amount is less than 0.1 g, the shift reaction efficiency is not sufficient, and if it exceeds 20 g, the noble metals may aggregate to exhibit catalytic activity, and the cost may become expensive.

As an oxide which can be mix | blended with a shift reaction catalyst layer, what was described in the said upper layer can be used, and it is especially preferable that it is a lattice defect oxide. As the above-described upper layer, the oxide preferably includes one or more oxides selected from the group consisting of vanadium, titanium, tungsten, indium, cerium, praseodymium, samarium, ytterbium, or neodymium, and these are Two or more complex oxides may be used. Particularly preferred is an oxide or composite oxide containing cerium and / or titanium. As described above, when titanium is included, the effect of decomposing H ₂ O to obtain O is excellent, and when cerium is included, the oxygen carrying ability is improved because the carrying ability of active oxygen is excellent.

Examples of such metal oxides include phosphors such as CeO ₂ , PrO ₂ , ThO ₂ , PaO ₂ , ZrO ₂ , and PuO _{2 represented} by the AX ₂ type when the cations are A and B and the anion is X. There are stone type, rutile type such as TiO ₂ , GeO ₂ , IrO ₂ , RuO ₂ , and anatase type TiO ₂ . Further, CaTiO ₃ represented by _{ABX 2, SrTiO 3, BaTiO 3} , CdTiO 3, CdTiO 3, PbTiO 3, CaCeO 3, SrCeO 3, BaCeO 3, CdCeO 3, PbCeO 3, NaNbO 3, KNbO 3, NaWO 3, CaZrO Perovskite type complex oxides which are complex oxides containing lattice defect oxygen such as ₃ , SrZrO ₃ , BaZrO ₃ , PbZrO ₃ , CaSnO ₃ , SrSnO ₃ , ZrCeO ₃ can also be preferably used.

  The concentration of these oxides and composite oxides in the shift reaction catalyst layer is preferably 25% by mass or more, more preferably 25 to 75% by mass, and particularly preferably 33 to 66% by mass. If it is less than 25% by mass, the CO removal rate may not be sufficient. In addition, when using together 2 or more types of elements, it calculates with the total amount. Note that oxygen atoms are not included in the above calculation. In the present invention, a metal oxide or a noble metal can be blended in both the upper layer and the shift reaction catalyst layer, but these may be the same or different in the upper layer and the shift reaction catalyst layer. Good.

  In the present invention, it is preferable to add an oxide containing aluminum or zirconium to the upper layer or the shift reaction catalyst layer. When alumina or zirconia is blended, the heat resistance of the upper layer and the shift reaction catalyst layer can be improved. These can be used simultaneously as coating aids. The blending amount of aluminum or zirconium is preferably 0 to 10% by mass in the upper layer or the shift reaction catalyst layer.

  In the present invention, silica, magnesia or the like may be further added to the upper layer or the shift reaction catalyst layer. These inorganic compounds are widely used as catalyst carrier components and coating aids, and it is easy to obtain raw materials and to produce and handle the carrier. It is preferable that these compounding quantities are 0-5 mass% in an upper layer or a shift reaction catalyst layer.

In the present invention, the mass of the upper layer with respect to the mass of the shift reaction catalyst layer is not particularly limited, but the mass ratio of shift reaction catalyst layer: upper layer is more preferably 3: 1 to 1: 3, more preferably 2: 1-1: 2. When the mass ratio of each layer is adjusted to the above range, the balance between the H ₂ + CO production rate and the CO oxidation efficiency is good, and even if the CO concentration fluctuates based on the shift reaction gas amount fluctuation, the CO removal efficiency is improved. Excellent.

  The monolith catalyst used in the present invention can be prepared by supporting each layer on a honeycomb monolith. This is because when the honeycomb monolith is used, it is easy to fill the catalyst in the catalyst filling portion of the shift reaction apparatus, and the honeycomb structure can ensure the gas permeability of the raw material gas and the reformed gas. Further, when the raw material gas is supplied, the catalyst can be prevented from being heated and calcined, and the catalyst life and the catalytic activity can be improved.

  As a material constituting the honeycomb monolith, ceramic honeycomb (ceramics, 400 cells to 3000 cells, diameter 35 mmφ), metal foam (Ni-Cr, 20 pores / inch to 50 pores / inch, diameter 100 mmφ) and / or ceramic foam (ceramics, 9 poles / inch to 30 poles / inch, diameter 75 mmφ), and any of them may be used. Cera honeycomb, metal foam, and Cera foam are preferable because they are excellent in pressure loss and easy in coating technology. In order to ensure air permeability and catalytic activity, the cell width is preferably 0.01 to 10 mm, and the number of cells per liter is preferably 100 to 10,000.

  The catalyst is supported on the honeycomb monolith, for example, the components constituting the shift reaction catalyst layer are prepared in a slurry form, supported on the honeycomb monolith, dried, and fired. Next, in order to support the upper layer on the fired product after applying the shift reaction catalyst, for example, the above-described components constituting the upper layer are prepared in a slurry form, supported on the fired product, dried, and fired. In this method, for example, natural drying, evaporation to dryness, rotary evaporator, spray dryer, drying with a drum dryer or the like can be used. What is necessary is just to select drying time suitably according to the method to be used. Depending on the case, it is good also as drying in a baking process, without performing a drying process. The honeycomb monolith catalyst may be fired at a temperature of 200 to 1,000 ° C. for 30 to 480 minutes. If necessary, pressure reduction, heating, spraying, etc. may be performed together.

  As described above, since the monolith catalyst for shift reaction of the present invention is excellent in CO removal rate, the shift catalyst reactor can be miniaturized and is particularly advantageous. The coating of the catalyst layer and the upper layer on the honeycomb monolith is, for example, 1 selected from the group consisting of vanadium, titanium, tungsten, indium, cerium, praseodymium, samarium, ytterbium, zirconium, niobium, tantalum, or neodymium on the honeycomb monolith. It may be produced by attaching more than one kind of metal by impregnation or the like, then firing the honeycomb monolith, and then supporting the noble metal such as platinum, rhodium, palladium, ruthenium, iridium and osmium on the fired product. Further, the honeycomb monolith may be manufactured by applying, drying, and firing a slurry in which one or more elements selected from Mn, Fe, Co, and Cu and a heat-resistant material such as alumina are mixed. Further, a catalyst prepared in advance may be coated on the honeycomb monolith with a binder.

  The shift catalyst according to the present invention can exhibit an excellent CO removal rate as described above. By using the shift catalyst having such characteristics for the shift reaction in the fuel reformed gas, it is possible to efficiently reduce the CO concentration in the fuel gas supplied to the fuel cell. In particular, even if the space velocity is high, the CO concentration can be reduced to a very low concentration, so that it can be used effectively even in an automobile or the like where the mounting range is limited.

  Hereinafter, the present invention will be specifically described based on examples. In addition, this invention is not limited only to these Examples. In the examples, “%” represents a mass percentage unless otherwise specified.

(Comparison catalyst powder 1 preparation)
A cerium-zirconium composite oxide having a BET specific surface area of 70 m ² / g Ce: Zr = 68: 32 (mol ratio) was mixed with dinitrodiamine platinum complex salt having a Pt metal content of 8.451 mass% and containing Pt per weight of the catalyst powder. Comparative catalyst powder 1 was obtained by impregnating and supporting so that the amount was 0.5% by mass, followed by drying and firing.

  Coating: Alumina sol was added as a coating aid to the comparative catalyst powder 1 and dispersed for 1 hour with a ball mill, then 0.12 L of cordierite honeycomb monolysis corresponding to 400 cells per square inch was converted into catalytic active powder. Was applied so as to correspond to 24 g, and dried and fired to obtain Comparative Catalyst 1.

(Example 11: Preparation of catalyst powder 11)
At the time of impregnation with the comparative catalyst powder 1, manganese nitrate was added so that the Mn content per mass of the catalyst powder was 0.05% by mass, and thereafter, catalyst powder 11 was obtained by the same method.

  Coating: Alumina sol was added as a coating aid to the comparative catalyst powder 1 and dispersed for 1 hour with a ball mill, then 0.12 L of cordierite honeycomb monolysis corresponding to 400 cells per square inch was converted into catalytic active powder. Was applied so as to correspond to 12 g, dried and fired, and then the catalyst powder 11 was further applied and dried and fired by the same method to obtain the catalyst 11.

(Example 12)
In Example 11, catalyst powder 12 and working catalyst 12 were obtained by the same method except that manganese nitrate was changed to iron nitrate.

(Example 13)
In Example 11, catalyst powder 13 and working catalyst 13 were obtained by the same method except that manganese nitrate was changed to cobalt nitrate.

(Example 14)
In Example 11, catalyst powder 14 and working catalyst 14 were obtained in the same manner except that manganese nitrate was changed to copper nitrate.

(Example 15)
Catalyst powder 15 was obtained by impregnating and supporting cerium oxide having a BET specific surface area of 100 m ² / g so that the Cu content per weight of the catalyst powder was 5.0 mass%, followed by drying and firing.

  Coating: Alumina sol as a coating aid was added to catalyst powder 1 and dispersed for 1 hour with a ball mill. Then, 0.1 g of cordierite honeycomb monolysis corresponding to 400 cells per square inch was added to 12 g of catalyst active powder. The catalyst powder 15 was further applied and dried and fired in the same manner as described above, and the catalyst 15 was obtained.

(Comparative Example 2)
A similar method except that anatase-type titanium oxide (BET specific surface area 40 m ² / g) is used instead of the cerium-zirconium composite oxide of BET specific surface area 70 m ² / g Ce: Zr = 68: 32 (mol ratio). Comparative catalyst powder 2 and comparative catalyst 2 were obtained.

(Example 21)
At the time of impregnation with the comparative catalyst powder 2, manganese nitrate was added so that the Mn content per weight of the catalyst powder was 0.05% by mass, and thereafter catalyst powder 21 was obtained by the same method.

  Coating: Alumina sol as a coating aid was added to catalyst powder 2 and dispersed in a ball mill for 1 hour. The catalyst powder 21 was further applied and dried and fired in the same manner as described above to obtain an implementation catalyst 21.

(Example 22)
In Example 21, catalyst powder 22 and working catalyst 22 were obtained in the same manner except that manganese nitrate was changed to iron nitrate.

(Example 23)
In Example 22, a catalyst powder 23 and an implementation catalyst 23 were obtained in the same manner except that manganese nitrate was changed to cobalt nitrate.

(Example 24)
In Example 22, catalyst powder 24 and practical catalyst 24 were obtained in the same manner except that manganese nitrate was changed to copper nitrate.

(Comparative Example 3)
A comparative catalyst was prepared in the same manner except that cerium oxide (BET specific surface area 130 m ² / g) was used instead of the cerium-zirconium composite oxide of BET specific surface area 70 m ² / g Ce: Zr = 68: 32 (mol ratio). Powder 3 and comparative catalyst 3 were obtained.

(Example 31)
At the time of impregnation with the comparative catalyst powder 3, manganese nitrate was added so that the Mn content per weight of the catalyst powder was 0.05% by mass, and thereafter catalyst powder 31 was obtained by the same method.

  Coating: Alumina sol was added as a coating aid to the comparative catalyst powder 3 and dispersed in a ball mill for 1 hour, then 0.12 L cordierite honeycomb monolysis corresponding to 400 cells per square inch was converted to catalytic active powder. Was applied so as to correspond to 12 g, dried and fired, and then the catalyst powder 31 was further applied and dried and fired by the same method to obtain the catalyst 31.

(Example 32)
In Example 31, a catalyst powder 32 and an implementation catalyst 32 were obtained by the same method except that manganese nitrate was changed to iron nitrate.

(Example 33)
In Example 32, catalyst powder 33 and implementation catalyst 33 were obtained in the same manner except that manganese nitrate was changed to cobalt nitrate.

(Example 34)
In Example 32, catalyst powder 34 and implementation catalyst 34 were obtained in the same manner except that manganese nitrate was changed to copper nitrate.

Example 4
As a pretreatment for the reaction, 1 Hr activation treatment was performed at 400 ° C. in a nitrogen atmosphere containing 2% hydrogen using 36 ml of the catalyst prepared in each of Comparative Examples and Examples.

Next, while changing the catalyst temperature, the reaction gas (Total) having a gas composition (CO: H ₂ O: H ₂ : CO ₂ : N ₂ = 2.5: 24: 35: 15: 23.5 [vol%]) : 30 L / min), and the outlet gas composition was analyzed by gas chromatography.

  The performance of each catalyst was evaluated based on how many times the maximum activity of the catalyst was compared to the comparative example.

  The electrode catalyst for a fuel cell in which the noble metal-containing particles have a core-shell structure of at least a core part of a noble metal alloy layer and a core part formed on the outer periphery of the core part and a shell part having a different composition Is useful as a fuel cell electrode catalyst with a long life.

Claims (14)

A platinum metal-containing monolith catalyst used for a shift reaction of a carbon monoxide-containing gas having an O ₂ concentration of 0.01% by volume or less, wherein the shift reaction catalyst layer does not contain Mn, Fe, Co or Cu on the monolith support; A monolithic catalyst for shift reaction, characterized by having an upper layer containing at least one element selected from Mn, Fe, Co, and Cu stacked thereon.   The monolith catalyst for shift reaction according to claim 1, wherein the upper layer has a hydrocarbon selective oxidation function or a CO selective oxidation function.   The monolith catalyst for shift reaction according to claim 1 or 2, wherein the upper layer contains a noble metal and a metal oxide.   The monolith catalyst for shift reaction according to claim 3, wherein the metal oxide is an oxide containing lattice defect oxygen.   The monolith catalyst for shift reaction according to claim 4, wherein the oxide containing lattice defect oxygen is a perovskite complex oxide.   The metal oxide is a metal oxide containing one or more selected from the group consisting of vanadium, titanium, tungsten, indium, cerium, praseodymium, samarium, ytterbium, zirconium, niobium, tantalum or neodymium. 6. The monolith catalyst for shift reaction according to any one of 5 above.   The monolith catalyst for shift reaction according to claim 6, wherein the metal oxide is a metal oxide containing cerium and / or titanium.   The monolith catalyst for shift reaction according to any one of claims 3 to 7, further comprising an oxide containing aluminum and / or zirconium in addition to the metal oxide.   The monolithic catalyst for shift reaction according to claim 1 or 2, wherein the shift reaction catalyst layer includes a noble metal and a metal oxide having oxidation-reduction ability.   The monolith catalyst for shift reaction according to claim 9, wherein the metal oxide is a metal oxide containing lattice defect oxygen.   The monolith catalyst for shift reaction according to claim 10, wherein the metal oxide containing lattice defect oxygen is a perovskite complex oxide.   The metal oxide is a metal oxide containing at least one selected from the group consisting of vanadium, titanium, tungsten, indium, cerium, praseodymium, samarium, ytterbium, zirconium, niobium, tantalum or neodymium. The monolith catalyst for shift reaction according to any one of 11 above.   The monolith catalyst for shift reaction according to claim 12, wherein the metal oxide is a metal oxide containing cerium and / or titanium.   The monolith catalyst for shift reaction according to any one of claims 9 to 13, wherein an oxide containing aluminum and / or zirconium is further blended in addition to the metal oxide.