JPH08206500A - Palladium-based catalyst, combustion catalyst, and combustion device - Google Patents

Abstract

PURPOSE: To maintain the activity for a long period of time to restrain the generation of nitrogen oxide by forming a catalyst out of various metal oxides and the dispersion ratio of noble metal containing palladium equal to or less than a specific value and making a catalyst particle diameter equal to or more than a specific value. CONSTITUTION: The catalyst consists of at least any one kind of oxide of a number of rare earth metals such as Ni, Co, Mn, V, Fe, Mg, Ca, Sr, Ba, an oxide of perovskite structure containing at least one kind of a number of rare earth elements such as Ni, Co, Mn, V, Fe, or oxide particles 10 selected from any of oxides, to which a metal element is added, by doping, and noble metal particles 7 which are adhered to the surfaces of the oxide particles 10 and containing at least palladium. And, the catalyst particles, in which dispersion ratio of the noble metal 7 containing palladium is 5% or less, and the diameter of catalyst particles 9 is 0.1μm or less, are provided. As the result, oxygen in the atmosphere is efficiently taken in from the oxide particles 10 so as to be supplied to an active site of combustion reaction. That is, difficiency of oxygen can be avoided and hence a high oxide state can be ensured.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a palladium catalyst, a palladium combustion catalyst, and a combustor equipped with the palladium combustion catalyst.

[0002]

2. Description of the Related Art In recent years, with the depletion of petroleum resources and the like, alternative energy sources have been required, and much attention has been paid to efficient use of energy resources. And, among the means to meet these demands, for example, a gas turbine / steam turbine combined cycle power generation system that uses natural gas as a fuel, or a coal gasification gas turbine /
A steam turbine combined cycle power generation system has been developed. In addition, these power generation systems have higher power generation efficiency than conventional steam turbines and power generation systems that use fossil fuels, so fuels such as natural gas and coal gasification gas whose usage is expected to increase in the future. Is expected as a power generation system that can effectively convert electricity into electricity.

By the way, in a gas turbine combustor used in a gas turbine power generation system, generally, a homogeneous reaction combustion system is employed in which a mixture of fuel and air is ignited by a spark plug to perform combustion. ing.

FIG. 5 is a cross-sectional view showing an example of the structure of a main part of a gas turbine combustor, where 1 is a casing, 2 is a fuel nozzle,
3 is a spark plug (ignition element), 4 is a combustion gas (for example, air) supply port 4a, a cooling air supply port 4b, and a dilution air supply port 4c on the side wall, and the required combustion gas is a turbine nozzle. No. 5 is a combustor liner. Then, in the combustor, the fuel gas injected from the fuel nozzle 2 is mixed with the air supplied from the combustion gas supply port 4a, and ignited and burned by the spark plug 3. With this combustion, the cooling air supply port 4b
And the required air is supplied from the dilution air supply port 4c,
The combustion gas cooled to a predetermined temperature (turbine inlet temperature) has a function of being injected into the turbine through the turbine nozzle 5.

However, since the gas turbine combustor uses air as a combustion gas, environmental pollution due to the production of nitrogen oxides (NO _x ) during combustion is a problem. In other words, the generation of nitrogen oxides depends on the combustion temperature.
Although it rapidly increases when the temperature exceeds 1500 ° C, there is a problem that a fuel concentration distribution exists in the combustor and locally a high temperature portion exceeding 2000 ° C is generated to generate a large amount of nitrogen oxides.

In order to solve such a problem, a catalytic combustion system has been proposed in which a mixture of fuel and air (oxygen-containing gas, hereinafter referred to as air) is burned using a catalyst. According to this catalytic combustion method, since a lean fuel can be burned by a catalytic action, it is possible to perform combustion while maintaining the maximum temperature in the combustor at about 1600 ° C. or lower at which nitrogen oxides are rapidly generated. Therefore, clean exhaust gas can be obtained without lowering the energy efficiency.

[0007]

However, when the combustion temperature is set to 1300 ° C. or higher as in the high temperature gas turbine, the temperature of the combustion catalyst also exceeds 1300 ° C. Deterioration of strength and performance and damage are problems. Therefore, there has been proposed a combustion method including a catalyst portion and a gas-phase reaction portion in which a catalyst is not installed downstream thereof, in which the catalyst portion burns and the gas-phase reaction portion downstream thereof further burns. Such a combustion system can be used at low temperature, volatilization and disappearance of the active component, and deterioration of the catalytic active component and carrier due to rapid sintering are suppressed, and the strength and performance of the combustion catalyst are suppressed. It is possible to obtain a combustor with reduced deterioration damage and improved reliability. On the other hand, noble metals such as platinum and palladium are known as catalytically active components used in this combustion system. Although there are various configurations of combustion catalysts having such a noble metal as a catalytically active component, for example, in order to prevent the catalytically active components from agglomerating and coarsening at the catalytic combustion temperature, they are relatively large with a diameter of several micrometers or less. It is constituted by applying and forming catalyst particles in which ceramic particles such as zirconia particles carry a noble metal on a heat-resistant honeycomb substrate. The durability of the combustion catalyst can be further improved by the structure of the combustion catalyst.

Of these combustion catalysts, in order to burn a fuel containing methane as a main component, which will be used in the future, by an oxidation reaction, a combustion catalyst containing palladium as a catalytically active component will react from a low temperature. It is particularly preferable because it starts.

Further, as a result of intensive studies by the present inventors,
It was revealed that palladium has higher catalytic activity in the oxidized state (PdO) and lower catalytic activity in the metallic state (Pd). In addition, due to the equilibrium governed by the partial pressure of oxygen and the ambient temperature, palladium releases oxygen at 900 ° C or higher under the operating conditions of a gas turbine, becomes a metallic state (Pd), and raises the catalyst temperature to 900 ° C or higher. It has the property of not doing. When a combustion catalyst containing palladium as an active component having such characteristics is applied to the catalytic combustion system, the temperature is easily controlled.

However, like a gas turbine combustor,
When the combustion load (oxidation reaction amount) is large, the equilibrium
Even in the temperature range of PdO, during long-term continuous combustion operation, palladium is reduced by the combustion reaction (oxidation reaction of fuel),
It was clarified that there is a problem that the ratio of Pd with low activity increases, the catalyst performance decreases, and the catalyst temperature decreases. The decrease in the catalyst temperature causes a misfire in the gas-phase combustion section installed downstream of the catalyst section, which makes it difficult to operate the gas turbine.

In general, a system catalyst containing palladium as an active ingredient is a Pd-O oxide state in which oxygen is dissociated and adsorbed on the catalyst surface, and hydrocarbons are oxidized to reduce the palladium itself to a metal state ( Pd) and then oxidized again to Pd-O
Is said to be a redox reaction in which an oxidation reaction proceeds. In the usual oxidation reaction of hydrocarbons, since the reaction amount is not so large, the redox cycle smoothly proceeds on the catalyst surface. However, in a reaction system with a large combustion load, such as a gas turbine combustor, the redox cycle is out of balance and the surface
It is considered that oxygen of Pd-O is easily consumed and oxygen of bulk palladium oxide (PdO) existing inside the palladium catalyst moves to the surface and is used for fuel oxidation. To be In other words, in the initial state, most of the palladium in the palladium-based catalyst is in the oxidized state and exhibits high activity, but oxygen in the bulk is consumed as the combustion reaction progresses, and the metal state (Pd) of the catalyst surface It is believed that the proportion increases and the catalytic activity decreases.

The present invention has been made in view of the above circumstances, and an object of the present invention is to provide a palladium-based catalyst that retains and exhibits high activity over a long period of time.

Another object of the present invention is to provide a palladium-based combustion catalyst capable of maintaining the required activity for a long period of time even at high temperatures.

A further object of the present invention is to provide a combustor which can maintain the required activity for a long period of time and suppress the generation of nitrogen oxides.

[0015]

The palladium-based catalyst according to the present invention comprises a rare earth metal oxide, Ni, Co, Mn, V, Fe and M.
At least one of oxides of g, Ca, Sr and Ba, at least one of rare earth elements, Ni, Co, Mn, V and Fe 1
An oxide having a perovskite structure containing a certain element, or an oxide particle selected from any of the oxides doped with a metal element, and a noble metal particle containing at least palladium deposited on the oxide particle surface. A palladium-based catalyst characterized by comprising palladium-based catalyst particles having a dispersion rate of the noble metal containing palladium of 5% or less and a catalyst particle diameter of 0.1 μm or more. The palladium-based combustion catalyst according to the present invention comprises a durable support having several other gas channels that are partitioned and independent of each other, and a palladium-based catalyst that is adhered to and carried on the inner wall surface of the gas channel of the durable support. A palladium-based combustion catalyst comprising catalyst particles, wherein the palladium-based combustion catalyst is a rare earth metal oxide, Ni, Co, M.
Perovskite structure oxide containing at least one kind of oxide of n, V, Fe, Mg, Ca, Sr and Ba, rare earth element, and at least one kind of element of Ni, Co, Mn, V and Fe , Or a noble metal containing at least palladium deposited on the oxide particle surface selected from any of the oxides doped with a metal element, and the catalyst particle diameter is 0.1 μm.
It is characterized by including the above palladium-based catalyst particles and having a dispersion rate of the noble metal containing palladium of 5% or less.

The combustor according to the present invention is a gas mixing section for mixing a fuel gas supply port, an air supply port, a fuel gas supplied from the fuel gas supply port and an oxygen-containing gas supplied from the air supply port. And a combustion catalyst arranged in a mixed gas flow path flowing out of the gas mixing section, wherein the combustion catalyst has several other gas flow paths that are partitioned and independent from each other. A palladium-based combustion catalyst comprising a durable support and palladium-based catalyst particles deposited and carried on the inner wall surface of the gas flow path, wherein the palladium-based combustion catalyst is a rare earth metal oxide, Ni, Co, Mn,
Oxide of perovskite structure containing at least one kind of oxide of V and Fe, rare earth element, Ni, Co, Mn, V, Fe, Mg, Ca, Sr and Ba, or An oxide particle selected from any of the oxides doped with a metal element, which is composed of a noble metal containing at least palladium deposited on the surface of the oxide particle and has a catalyst particle diameter of 0.1 μm.
It is characterized by including the above palladium-based combustion catalyst particles and having a dispersion rate of the noble metal containing palladium of 5% or less.

The present invention was achieved as a result of further research on palladium-based catalysts. That is, the present inventors have made catalyst particles in which metal oxide particles that easily incorporate and release oxygen into the oxide lattice carry a catalyst active component composed of at least a noble metal, and the dispersion ratio of the catalyst active component is further increased. It has been found that when the value is lowered, the catalytic performance is higher than that in the case of particles having a catalytically active component alone, and the present invention has been completed.

In the present invention, the dispersion ratio of the noble metal containing palladium means the number of atoms of the noble metal exposed on the surface in the noble metal in the catalyst particles and the total number of atoms of the noble metal contained in the catalyst particles. The value is divided by the number (total weight of precious metal contained, atomic weight of precious metal) and expressed as a percentage. The number of noble metal atoms exposed on the surface of the catalyst particles is a value calculated by utilizing the fact that CO molecules are adsorbed corresponding to the noble metal atoms. In this calculation, we consider that CO and exposed noble metal atoms are adsorbed in a one-to-one relationship.

The details of the present invention will be described below.

In general, in order to enhance the activity of the unit noble metal amount, the noble metal catalyst has the noble metal particles made extremely small and supported on the carrier to increase the dispersion rate as schematically shown in FIG. 6, for example. It takes the form. In FIG.
Reference numeral 6 denotes a carrier (for example, alumina) supporting the palladium particles 7, 8 denotes a palladium atom or a catalytically active site present in the palladium particles 7, and 9 denotes an interface involved in the combustion reaction. Here, the dispersion ratio of the palladium (a noble metal containing palladium) is defined as the palladium atom 8 existing in the reaction interface 9 or the active site of the palladium atom 8 existing in the palladium particle 7 or the total amount of active sites in the catalytic reaction. If the ratio is set, palladium particles 7
The smaller the diameter, the higher the dispersion rate. In general, for example, in a palladium catalyst system, the particle size is several
It is selected to have a thickness of about nm or less (high dispersion ratio), and exhibits high activity in the initial stage, but the activity decreases due to aggregation due to heat in the combustion reaction.

When the combustion load (reaction rate) is large as in a gas turbine, in addition to the adsorbed oxygen existing at the reaction interface of the palladium-based catalyst, the oxygen existing as lattice oxygen inside the interface of the palladium-based catalyst is also present. Is also used in the reaction. Therefore, with a palladium-based catalyst with a high dispersion ratio,
With the passage of the reaction time, oxygen existing inside disappears (forms metal Pd) and the catalytic activity decreases.

On the other hand, as shown schematically in FIG. 7, the present inventors used catalyst particles in which a precious metal containing palladium was supported on a relatively large ceramic having a diameter of several μm or less, and the dispersion rate was lowered. Proceeded with the examination. In FIG. 7, 6 is a carrier (for example, alumina) carrying catalyst particles 10, 11 is ceramic particles carrying palladium particles 7 to form catalyst particles 10, and 8 is a palladium atom or catalyst present in the palladium particles 7. Active points and 9 respectively indicate interfaces involved in the combustion reaction. In the structure of the catalyst particles 10, since the diameter of the catalyst particles 10 is large and the number of the interfaces 9 involved in the combustion reaction is small, the dispersion ratio of the palladium-based catalyst is low, and the initial catalyst activity is low, but the heat resistance is significantly high. It will be improved. Even when the combustion load (reaction rate) is large as in a gas turbine, oxygen existing in large amounts as lattice oxygen inside the catalyst from the reaction interface is utilized for the reaction, and the problem of catalyst activity reduction is also ameliorated.

In the palladium-based catalyst shown in FIG. 7, since oxygen is taken in from the lattice oxygen through the reaction interface, in a certain reaction atmosphere (temperature, reaction gas partial pressure), the metal state (Pd) and the oxide are mixed. The ratio with the state (PdO) changes so that it has a constant steady state value. For example, in the catalyst system having the configuration shown in FIG. 6, the activity is remarkably reduced with the combustion reaction, while the rate of decrease of the catalyst activity is moderate and the degree of the decrease is improved, but the catalyst activity is still reduced. Still occurs, and there is a problem in stability for a gas turbine combustor.

With these points in mind, the present inventors have used oxide-based particles that easily absorb and release oxygen as the ceramic 11 that supports the palladium particles 7 to form the catalyst particles 10. It has been found that it is effective to select the size of 10 within a predetermined range while reducing the dispersion ratio of palladium.

In the present invention, rare earth metal oxides (eg, oxides of Ce, La, etc.), Ni, Co, M are used as oxides.
Perovskite structure oxide containing at least one kind of oxide of n, V, Fe, Mg, Ca, Sr and Ba, rare earth element, and at least one kind of element of Ni, Co, Mn, V and Fe Or an oxide selected from any of the above oxides doped with a metal element. Especially as oxide
Valuable metal elements such as Fe, Mn, Co, Ti, La, Nd, Y,
At least 1 selected from Pr, Gd, Eu, Sm, Pm, Sc, Rh
A cerium oxide doped with a seed and having an atomic ratio of metal element / cerium of 1/99 to 10/90 is preferable because the catalytic activity can be increased.

The palladium-based catalyst may be supported on the oxide particles by, for example, electroless plating on the surface of the particles such as oxide particles. It is also possible to adopt a manufacturing method in which the material is molded or made into particles. In any case, unless it is densified in particular, it usually has fine pores and has a form in which gas communicates on the inner side.

In the present invention, the active component of the catalyst is a noble metal containing palladium and / or palladium oxide as a main component (at least 50% by mass, preferably 80% by mass or more). In addition to the active component of palladium, a noble metal such as gold or platinum may be included. further,
Nickel, magnesium, titanium, vanadium, chromium, manganese, iron, cobalt, copper, zinc, molybdenum, ruthenium, rhodium, as a co-catalyst in the catalyst particles,
Rare earths containing silver, platinum, gold, lanthanoids (scandium, yttrium, lanthanum, cerium, praseodymium, neodymium, promethium, samarium, europium, gatolinium, terbium, dysprosium, holmium, erbium, thulium, ytterbium, lutetium) and oxidation of these elements You may add a thing. Here, the mass ratio of the oxide of the palladium-based catalyst to the noble metal is preferably 90:10 to 20:80 oxide: noble metal. In the palladium-based catalyst particles according to the present invention, the particle diameter is 0.1 μm or more, preferably 0.1 to 10 μm.
m, more preferably 0.5 to 5 μm. The reason is that if the particle size is less than 0.1 μm, it is difficult to sufficiently reduce the dispersion rate, and as a result, excellent catalytic activity cannot be obtained. In addition, in this palladium-based catalyst particle, the lower selection rate of 5% or less compared to the generally desired dispersion rate is that if it exceeds 5%, the required catalyst activity for a long period of time is required. This is because it has been experimentally confirmed that it cannot hold and exhibit.

Further, although the palladium-based catalyst particles according to the present invention can be used in the form of particles, for example, heat resistant ceramics such as cordierite, alumina, zirconia, magnesia and heat resistant metals such as stainless steel. It is also possible to use a carrier made of a material such as, for example, a honeycomb-shaped structure as a carrier, and to adhere and support the carrier surface. Particularly, in a combustor or the like, it is preferable to use a honeycomb-shaped structure as a carrier in consideration of ventilation resistance and the like. That is, in the durable carrier having the honeycomb structure, the deposition and loading of the active catalyst on the inner wall surfaces of several other gas channels which are partitioned and independent from each other,
What was manufactured by the method of apply | coating the slurry containing a palladium-type catalyst particle to the inner wall surface of a gas flow path, and sintering it after that is preferable. Here, in order to create porosity in the slurry,
It is desirable to premix about 20 to 90 mass% of powder such as alumina, zirconia, magnesia, and titania.

[0029]

The palladium-based catalyst particles according to the present invention are efficiently supplied with oxygen in the atmosphere from oxide particles that easily absorb and release oxygen, and are supplied to active points where a combustion reaction occurs. That is, during the combustion reaction, the phenomenon of oxygen deficiency disappears in the palladium-based catalyst particles involved in the combustion reaction, and the palladium-based catalyst can always and easily ensure an oxide state with high catalytic activity. A decrease in activity will be avoided, and a stable catalytic function will be exhibited.

Further, in the case of the combustion catalyst and combustor according to the present invention, since they are provided with the palladium-based catalyst particles exhibiting the above-mentioned action, the gas can be obtained by utilizing them for high temperature gas generation and combustion of a gas turbine, for example. High-temperature gas for driving a turbine can be efficiently generated and used, and it also has an excellent function in terms of cleaning exhaust gas.

[0031]

Embodiments of the present invention will be described below with reference to FIGS.

Example 1 Palladium was carried on cerium oxide (CeO ₂ ) particles having an average particle diameter of 0.3 μm by electroless plating, and the diameter was 0.5 μm.
m 2 palladium-based catalyst particles were obtained. With respect to the palladium-based catalyst particles, the palladium dispersion rate was 3% when the CO adsorption method was used to determine the number of atoms of the noble metal exposed on the surface of the catalyst particles. Figure 1
The structure of the palladium-based catalyst particles is schematically shown. 7 is a palladium-based particle, 8 is a palladium atom in the palladium-based particle 7, 11 is an oxide particle carrying the palladium-based particle 7, and 12 is a palladium-based particle. It is a pore in the particle 7.

Then, 100 parts by weight of the palladium-based catalyst particles, 150 parts by weight of γ-alumina fine powder, and 50 parts by weight of a binder containing alumina as a main component were mixed in a wet ball mill for 24 hours to prepare a slurry. This slurry was made into a cordierite honeycomb structure (diameter 30 mm, length 150 mm)
After coating on the inner wall surface of the separated openings (gas flow paths), drying and firing were performed to prepare a honeycomb type catalyst. In this honeycomb type catalyst, the external volume was 150
g of the catalyst composition was attached, and the dispersion ratio of palladium in the catalyst composition was 2.5%.

In the above, instead of cerium oxide (CeO ₂ ) particles, for example, neodymium oxide (Nd ₂ O ₃ ),
Similar results were observed for palladium-based catalyst particles that were constructed under the same conditions except that praseodymium oxide (Pr ₆ O ₁₁ ) was used.

Example 2 Palladium-based catalyst particles having a diameter of 0.5 μm were obtained by supporting palladium on lanthanum (La) -doped cerium oxide (CeO ₂ ) particles having an average particle diameter of 0.1 μm by electroless plating. A plurality of lanthanum-doped cerium oxide particles were present in the palladium-based catalyst particles, and the lanthanum / cerium atomic ratio of the lanthanum-doped cerium oxide particles was 5/95. Regarding the palladium-based catalyst particles, the dispersion ratio of palladium was measured by the CO adsorption method in Example 1
When measured in the same manner as in Example 1, the dispersion rate was 2%. FIG. 2 schematically shows the structure of the palladium-based catalyst particles, 7 is a palladium-based particle, 8 is a palladium atom in the palladium-based particle 7, 11 is an oxide particle carrying the palladium-based particle 7, 12 are pores in the palladium-based particles 7.

Next, 100 parts by weight of the palladium-based catalyst particles, 150 parts by weight of γ-alumina fine powder and 50 parts by weight of a binder containing alumina as a main component were mixed in a wet ball mill for 24 hours to prepare a slurry. This slurry was made into a cordierite honeycomb structure (diameter 30 mm, length 150 mm)
After coating on the inner wall surface of the separated openings (gas flow paths), drying and firing were performed to prepare a honeycomb type catalyst. In this honeycomb type catalyst, the external volume was 150
g of the catalyst composition was attached, and the dispersion ratio of palladium in the catalyst composition was 2%.

In the above description, a palladium-based material formed under the same conditions except that neodymium (Nd) -doped cerium oxide or yttrium (Y) -doped cerium oxide is used instead of the lanthanum (La) -doped cerium oxide (CeO ₂ ) particles. Similar results were observed for the catalyst particles.

Example 3 Palladium-based catalyst particles having a diameter of 1.0 μm were obtained by carrying out palladium electroless plating on neodymium (Nd) -doped cerium oxide (CeO ₂ ) particles having an average particle diameter of 0.7 μm. The neodymium-doped cerium oxide particles in the palladium-based catalyst particles had a neodymium / cerium atomic ratio of 8 /
It was 92. When the palladium dispersion ratio of the palladium-based catalyst particles was measured by the CO adsorption method in the same manner as in Example 1, the dispersion ratio was 4%.

Next, 50 parts by weight of the palladium-based catalyst particles, 100 parts by weight of γ-alumina fine powder, 50 parts by weight of cerium oxide powder having an average particle size of 0.5 μm, and 50 parts by weight of nickel oxide (NiO) powder having an average particle size of 0.1 μm. And 50 parts by weight of a binder containing alumina as a main component were mixed in a wet ball mill for 24 hours to prepare a slurry. This slurry was applied to the inner wall surface of the separated openings (gas passages) of a cordierite honeycomb structure (diameter 30 mm, length 150 mm), and then dried and fired to form a honeycomb catalyst. In this honeycomb type catalyst, 150 g of the catalyst composition adhered to the outer volume of 1 liter, and the dispersion ratio of palladium in the catalyst composition was 3%.

In the above, instead of neodymium (Nd) -doped cerium oxide (CeO ₂ ) particles, for example, La _0.2 Ba is used.
Similar results were observed for the palladium-based catalyst particles formed under the same conditions except that the perovskite oxide particles having the composition represented by _0.8 Fe _0.2 Co _0.8 O ₃ were used.

Example 4 Palladium-based catalyst particles having a diameter of 1.0 μm were obtained by carrying out palladium electroless plating on neodymium (Nd) -doped cerium oxide (CeO ₂ ) particles having an average particle size of 0.7 μm. The neodymium-doped cerium oxide particles in the palladium-based catalyst particles had a neodin / cerium atomic ratio of 5 /
It was 95. When the palladium dispersion ratio of the palladium-based catalyst particles was measured by the CO adsorption method in the same manner as in Example 1, the dispersion ratio was 4%.

On the other hand, the γ-alumina fine powder was dipped in an aqueous solution of nickel nitrate and then dried and fired to prepare a nickel oxide-supported γ-alumina fine powder containing 10 mass% of nickel oxide.

Next, 100 parts by weight of the palladium catalyst particles, 150 parts by weight of nickel oxide-supporting γ-alumina fine powder and 50 parts by weight of a binder containing alumina as a main component were mixed for 24 hours in a wet ball mill to prepare a slurry. This slurry was made into a cordierite honeycomb structure (diameter 30 mm,
After coating on the inner wall surface of the separated opening (gas flow path) having a length of 150 mm), the honeycomb catalyst was prepared by drying and firing. In this honeycomb type catalyst, 150 g of the catalyst composition adhered to the outer volume of 1 liter, and the dispersion ratio of palladium in the catalyst composition was 3%.

In the above, instead of neodymium (Nd) -doped cerium oxide (CeO ₂ ) particles, for example,
Similar results were observed for the palladium-based catalyst particles formed under the same conditions except that the perovskite oxide particles having the composition represented by La _0.2 Ba _0.8 Fe _0.2 Co _0.8 O ₃ were used.

Example 5 Neodymium (Nd) -doped cerium oxide (CeO ₂ ) particles having an average particle size of 0.7 μm were dipped in an aqueous solution of nickel nitrate and then dried and baked to contain 5% by mass of nickel oxide. Niobium-doped cerium oxide particles supporting nickel oxide were prepared. Then, palladium-supported catalyst particles having a diameter of 1.2 μm were obtained by supporting palladium on the nickel oxide-supported niobium-doped cerium oxide particles by electroless plating. When the palladium dispersion ratio of these palladium-based catalyst particles was measured by the CO adsorption method in the same manner as in Example 1, the dispersion ratio was 3%.

Next, 100 parts by weight of the palladium-based catalyst particles, 150 parts by weight of γ-alumina fine powder and 50 parts by weight of a binder containing alumina as a main component were mixed in a wet ball mill for 24 hours to prepare a slurry. This slurry was made into a cordierite honeycomb structure (diameter 30 mm, length 150 mm)
After coating on the inner wall surface of the separated openings (gas flow paths), drying and firing were performed to prepare a honeycomb type catalyst. In this honeycomb type catalyst, the external volume was 150
g of the catalyst composition was attached, and the dispersion ratio of palladium in the catalyst composition was 2.5%.

[0047] In the above, instead of neodymium (Nd) doped cerium oxide (CeO ₂₎ particles, also for example yttrium (Y) doped cerium oxide (CeO ₂₎ a palladium catalyst particles configured except for using particles as the same condition Similar results were observed.

Example 6 Palladium-based catalyst particles having a diameter of 1.0 μm were obtained by supporting palladium on neodymium (Nd) -doped cerium oxide (CeO ₂ ) particles having an average particle diameter of 0.7 μm by electroless plating. The neodymium (N
d) The neodymium / cerium atomic ratio of the doped cerium oxide particles was 5/95. The palladium-based catalyst particles were measured for the palladium-dispersion rate by the CO adsorption method in the same manner as in Example 1. The dispersion rate was 4%.

On the other hand, the γ-alumina fine powder was dipped in an aqueous chloroplatinic acid solution and then dried and baked to prepare a platinum-supported γ-alumina fine powder containing 2% by mass of platinum.

Next, 100 parts by weight of the palladium-based catalyst particles, 150 parts by weight of platinum-loaded γ-alumina fine powder and 50 parts by weight of a binder containing alumina as a main component were mixed for 24 hours in a wet ball mill to prepare a slurry. This slurry was made into a cordierite honeycomb structure (diameter 30 mm, length 150
mm), and then applied to the inner wall surface of the separated openings (gas flow paths), and dried and fired to prepare a honeycomb catalyst. In this honeycomb type catalyst, 150 g of the catalyst composition adhered to the outer volume of 1 liter, and the noble metal dispersion rate in the catalyst composition was 4%.

In the above, palladium-based catalyst particles formed under the same conditions except that, for example, praseodymium oxide (Pr ₆ O ₁₁ ) particles were used instead of neodymium (Nd) -doped cerium oxide (CeO ₂ ) particles, the same result was obtained. Was recognized.

Comparative Example 1 γ-alumina fine powder was dipped in an aqueous solution of palladium nitrate and then dried and fired to prepare a palladium-supported γ-alumina fine powder containing 8% by mass of palladium. When the dispersion ratio of palladium in this palladium-supported γ-alumina fine powder was measured by the CO adsorption method in the same manner as in Example 1, the dispersion ratio was 30%.

Next, 250 parts by weight of the palladium-supported γ-alumina fine powder and 50 parts by weight of a binder containing alumina as a main component were mixed in a wet ball mill for 24 hours to prepare a slurry. This slurry was applied to the inner wall surface of the separated openings (gas passages) of a cordierite honeycomb structure (diameter 30 mm, length 150 mm), and then dried and fired to form a honeycomb catalyst. In this honeycomb type catalyst, 150 g of the catalyst composition was adhered per 1 liter of the outer volume, and the dispersion ratio of palladium in the catalyst composition was 20%.

Comparative Example 2 γ-alumina fine powder was dipped in an aqueous palladium nitrate solution and dried and fired to prepare a palladium-supported γ-alumina fine powder containing 2% by mass of palladium. When the palladium dispersion ratio of this palladium-supported γ-alumina fine powder was measured by the CO adsorption method in the same manner as in Example 1, the dispersion ratio was 34%.

On the other hand, the γ-alumina fine powder was dipped in an aqueous solution of nickel nitrate and then dried and fired to prepare a nickel oxide-supported γ-alumina fine powder containing 10% by mass of nickel oxide.

Next, 100 parts by weight of the γ-alumina fine powder supporting palladium and γ-alumina fine powder supporting nickel oxide 1
50 parts by weight, and a binder 50 whose main component is alumina
A part was mixed by a wet ball mill for 24 hours to prepare a slurry. This slurry was applied to the inner wall surface of the separated openings (gas passages) of a cordierite honeycomb structure (diameter 30 mm, length 150 mm), and then dried and fired to form a honeycomb catalyst. In this honeycomb type catalyst, 150 g of the catalyst composition adhered to the outer volume of 1 liter, and the dispersion ratio of palladium in the catalyst composition was 25%.

Comparative Example 3 100 parts by weight of lanthanum (La) -doped cerium oxide (CeO ₂ ) particles having an average particle size of 0.1 μm and 100 gamma powder of γ-alumina
A part by weight was immersed in an aqueous solution of palladium nitrate and then dried and calcined to prepare palladium-based catalyst particles containing 8% by mass of palladium. The palladium-based catalyst particles were measured for the dispersion ratio of palladium by the CO adsorption method in the same manner as in Example 1. The dispersion ratio was 30%.

Next, 150 parts by weight of the palladium-based catalyst particles, 50 parts by weight of γ-alumina fine powder, and 50 parts by weight of a binder containing alumina as a main component are mixed in a wet ball mill for 24 hours, and then 150 parts by weight of the palladium-based catalyst particles. , Γ
A slurry was prepared by mixing 50 parts by weight of alumina fine powder and 50 parts by weight of a binder containing alumina as a main component in a wet ball mill for 24 hours. This slurry was applied to the inner wall surface of the separated openings (gas passages) of a cordierite honeycomb structure (diameter 30 mm, length 150 mm), and then dried and fired to form a honeycomb catalyst. In this honeycomb type catalyst, 150 g of the catalyst composition was adhered per 1 liter of the outer volume, and the dispersion ratio of palladium in the catalyst composition was 20%.

Example 7 The honeycomb type combustion catalysts constructed in the above Examples 1 to 6 and Comparative Examples 1 to 3 were assembled (mounted) in a gas turbine combustor and a durability test was conducted. That is, as shown in a cross-sectional view of a structural example of a main part in FIG. 3, the fuel gas supplied from the fuel gas supply port 13 and the combustion gas supplied from the air (combustion gas) supply port (not shown) A gas mixing section 14 for mixing (for example, an oxygen-containing gas such as air), the gas mixing section
14 for a gas turbine having a configuration comprising a mixed gas flow channel 15 flowing out of 14, a honeycomb type combustion catalyst 16 installed in the mixed gas flow channel 15 and promoting a combustion action of mixing flowing in the mixed gas flow channel In the combustor, the honeycomb type combustion catalysts of Examples 1 to 6 and Comparative Examples 1 to 3 were separately mounted and a durability test was conducted.

In this durability test, air containing 3% by volume of methane preheated to 400 ° C. was supplied at a flow rate of ³ Nm ³ at a pressure of 0.7 MPa, and a thermocouple installed at the outlet of the honeycomb-type combustion catalyst 16 was used. FIG. 4 shows the results of evaluating the performance of the combustion catalyst 14 by measuring the temperature of the combustion catalyst 16 at the same time as the test elapsed time. As can be seen from FIG. 4, Examples 1 to 1
In the case of the honeycomb-type combustion catalyst of No. 6, the catalyst temperature, which is an index of the required reaction catalyst function (catalytic activity), shows almost no change even after 600 hours, and in the case of Comparative Examples 1 to 3, After several tens of hours, the catalytic function started to decline, and when it exceeded 100 hours, most of the reaction catalytic function was lost.

The present invention is not limited to the above embodiments, and various modifications can be made without departing from the spirit of the invention. For example, regarding the palladium-based combustion catalyst 16, whether the shape of the opening of the mixed gas passage 15 and whether or not the palladium catalyst is attached / carried on all the inner wall surfaces of the mixed gas passage 15 Depending on the position or the position of the inner wall surface, etc.
Modifications appropriately selected and set in accordance with the spirit of the present invention can be adopted.

[0062]

As described above, the palladium-based catalyst particles according to the present invention can be used due to lack of oxygen in the catalyst even when used in the case of a large combustion load (reaction rate) such as a catalytic combustor. As a result, the problem that the catalytic activity is lowered is solved, and the activity is prevented from being lowered due to the aggregation of the catalytically active components. In other words, since it functions as a long-life combustion catalyst with stable performance, for example, in a gas turbine combustion catalyst or a gas turbine combustor,
It can be said that it exhibits excellent practicality and function.

[Brief description of drawings]

FIG. 1 is an enlarged cross-sectional view schematically showing a structural example of palladium-based catalyst particles according to the present invention.

FIG. 2 is an enlarged cross-sectional view schematically showing another structural example of the palladium-based catalyst particles according to the present invention.

FIG. 3 is a sectional view showing a configuration example of a main part of a combustor according to the present invention.

FIG. 4 is a characteristic diagram showing a characteristic example of a palladium-based combustion catalyst according to the present invention in comparison with a case of a conventional palladium-based combustion catalyst.

FIG. 5 is a cross-sectional view showing a main part configuration of a conventional gas turbine combustor.

FIG. 6 is an enlarged sectional view schematically showing a structural example of a palladium-based combustion catalyst.

FIG. 7 is an enlarged cross-sectional view schematically showing another structural example of the palladium-based combustion catalyst.

[Explanation of symbols]

1 ... Housing 2 ... Fuel nozzle 3 ... Spark plug 4 ... Combustor liner 4a ... Combustion air supply port 4b ... Cooling air supply port 4c ... Dilution air supply port 5 ... Turbine nozzle
6 ... Carrier 7 ... Palladium particle 8 ... Palladium atom
9 …… Reaction interface 10 …… Palladium catalyst particles 11 …… Ceramic particles that easily adsorb and release oxygen 12 …… Pores in palladium particle system 13 …… Fuel gas supply port 14 …… Gas mixing section 15 …… Mixing Gas channel 16 ...
... Honeycomb type palladium-based combustion catalyst

─────────────────────────────────────────────────── ─── Continuation of the front page (51) Int.Cl. ⁶ Identification code Internal reference number FI Technical display location B01J 23/648 23/656 23/89 ZAB A F23R 3/40 ZAB E A B 01J 23/64 102 A 104 A

Claims (4)

[Claims] 1. Rare earth metal oxide, Ni, Co, Mn, V, Fe
At least one of oxides, rare earth elements, Ni,
An oxide particle having a perovskite structure containing at least one element selected from the group consisting of Co, Mn, V, Fe, Mg, Ca, Sr and Ba, or an oxide particle selected from any of the above oxides doped with a metal element. A palladium-based catalyst particle having a noble metal containing at least palladium deposited on the surface of the oxide particles, the dispersion rate of the noble metal containing palladium being 5% or less, and the catalyst particle diameter being 0.1 μm or more. A palladium-based catalyst characterized by the above. 2. The oxide particles according to claim 1, which are cerium (Ce) oxides doped with a trivalent metal element (Me ⁺³ ) and have an atomic ratio of Me / Ce of 1/99 to 10/90. The palladium-based catalyst is characterized by 3. A durable support having a plurality of other gas channels that are partitioned and independent from each other, and palladium-based catalyst particles adhered to and carried on the inner wall surface of the gas channel of the durable support. Wherein the palladium-based combustion catalyst is a rare earth metal oxide, Ni,
Of a perovskite structure containing at least one kind of oxide of Co, Mn, V and Fe, a rare earth element, Ni, Co, Mn, V, Fe, Mg, Ca, Sr and Ba Oxide, or a noble metal containing at least palladium deposited on the oxide particle surface selected from any of the oxides doped with a metal element, the catalyst particle size is 0.1
A palladium-based combustion catalyst comprising palladium-based catalyst particles with a size of μm or more and having a dispersion rate of a noble metal containing palladium of 5% or less. 4. A fuel gas supply port, an air supply port, a gas mixing unit for mixing a fuel gas supplied from the fuel gas supply port and an oxygen-containing gas supplied from the air supply port, and the gas mixing unit. A combustor comprising a combustion catalyst arranged in a mixed gas flow path flowing out from the combustion catalyst, wherein the combustion catalyst has a plurality of other gas flow paths which are partitioned and independent from each other, and A palladium-based combustion catalyst comprising palladium-based catalyst particles deposited and supported on the inner wall surface of a gas flow path, and the palladium-based combustion catalyst containing rare earth metal oxides such as Ni, Co, Mn, V and Fe. At least one kind of oxide, rare earth element, Ni, Co, Mn,
It is deposited on the oxide particle surface selected from oxides of perovskite structure containing at least one element of V, Fe, Mg, Ca, Sr, and Ba, or any of the above oxides doped with a metal element. A combustor characterized by comprising a noble metal containing at least palladium, having a palladium-based combustion catalyst particle having a catalyst particle size of 0.1 μm or more, and having a dispersion ratio of noble metal containing palladium of 5% or less.