JPH0545293B2 - - Google Patents

Description

Detailed Description of the Invention <Industrial Field of Application> The present invention involves catalytically burning methane-based fuel, particularly natural gas containing methane as the main component and lower hydrocarbons such as ethane, propane, and butane, on a catalyst to produce nitrogen. We obtain clean combustion gas that does not substantially contain harmful components such as oxides (hereinafter referred to as NOx), carbon monoxide (hereinafter referred to as CO), and unburned hydrocarbons (hereinafter referred to as UHC), and the calorific value of the gas is converted into various types. The present invention relates to a combustion catalyst system and a combustion method using the same for use as a primary energy source, particularly in a gas turbine for power generation. <Prior art> A catalytic combustion system is known in which a dilute gas mixture of fuel mixed with air at a low concentration that does not fall within the combustible range is introduced into a catalyst layer and catalytically combusted on the catalyst to obtain high-temperature combustion gas. . Furthermore, when using such a catalytic combustion system to obtain combustion gas at a temperature of, for example, 600°C to 1500°C,
For example, even if air is used as an oxygen source, little or no NOx is generated, and CO,
It is also well known that it can be obtained without substantially containing UHC. Various systems have been proposed that utilize this clean, high-temperature combustion gas to generate heat or power, and general industrial exhaust gas treatment and thermal power recovery systems have already been put into practical use. Particularly in recent years, in response to increasing NOx regulations, research has begun to be conducted on the use of this high-temperature combustion gas as a primary power source such as gas turbines for power generation. These catalytic combustion systems include refractory metal oxides such as alumina and zirconia, and oxides of noble metals such as platinum, palladium, and rhodium, or base metals such as cobalt and nickel, which are catalytically active components.
Furthermore, a catalyst body in which a composite oxide such as LaCoO ₃ is supported on a monolithic carrier has been proposed. <Problems to be Solved by the Present Invention> In a system using the catalyst system as described above and used as a primary power source such as a gas turbine, the catalyst is used under conditions of 5 to 30 atmospheres due to the characteristics of the turbine. It is normal for gas turbines to reach high temperatures of 1,000 to 1,300 degrees Celsius, and in order to improve the efficiency of gas turbines, there is a trend toward even higher temperatures and pressures. When a catalyst is used under such conditions, a conventional catalyst deteriorates rapidly due to the high temperature, and in the worst case, the catalyst carrier may melt down and fly off, damaging turbine blades and the like. As a combustion method that avoids catalyst deterioration and damage as described above and achieves the same purpose, a part of the fuel is catalytically burned in the catalyst layer, and the gas temperature is raised to a temperature that induces secondary gas phase combustion. Next, the remaining unburned fuel is subjected to secondary gas phase combustion behind the catalyst layer, or if necessary, secondary fuel is introduced and the remaining unburned fuel and the newly added secondary fuel are burned in the gas phase. A combustion method has been discovered that produces clean combustion gas at or above the desired temperature. In this case, the purpose of combustion in the catalyst layer is to raise the gas temperature to a temperature that induces secondary gas phase combustion, and it is not necessarily necessary to completely burn the gas in the catalyst layer, but to induce secondary gas phase combustion. If the gas temperature reaches a temperature higher than the specified temperature, it is necessary to increase the temperature in the catalyst layer in order to avoid deterioration and damage to the catalyst and to maintain stable secondary gas phase combustion. Rather, it is preferable to have a large amount of remaining unburned fuel. The entire amount of fuel that can reach the desired temperature may be introduced into the catalyst layer, a portion of which may be catalytically combusted to raise the temperature, and the remaining unburnt fuel may be subjected to secondary gas phase combustion. This is then introduced from the rear of the catalyst layer as a secondary fuel, and combined with the remaining unburned fuel, it is
Subsequent catalytic combustion may be performed. In this case, it is possible to avoid setting the catalyst layer temperature to an unnecessarily high temperature, and it is possible to avoid deterioration and damage to the catalyst, which is more preferable. Here, the temperature required to induce secondary gas phase combustion is determined by the type of fuel, residual fuel concentration (theoretical adiabatic combustion gas temperature), linear velocity, etc., and varies significantly depending on the type of fuel. In other words, in the case of easily flammable fuels such as propane and diesel oil, a temperature of about 700°C is sufficient under normal usage conditions, but when using flame-retardant methane or natural gas whose main component is methane, In this case, a high temperature of 750 to 1000°C is required, depending on the usage conditions. In addition, in order to function as a gas turbine, it is necessary to reduce pressure loss, keep the combustor to a small capacity, and increase the combustion load factor, so the catalyst capacity must be as small as possible. As a result, the linear velocity at the entrance of the catalyst layer is 5~
It will be used under extremely harsh conditions that are not found in conventional catalytic reactions, with a space velocity of 40 m/s (500°C equivalent) and a space velocity of 8 to 6 million hours. Under such high-pressure conditions, a part of the fuel is catalytically combusted with flammable gas, especially a flame-retardant gas such as methane, in the catalyst layer, the gas temperature is raised to a temperature that induces secondary gas phase combustion, and then The remaining unburned fuel is burned in the gas phase behind the catalyst layer, or if necessary, the secondary fuel is introduced and added to the remaining unburned fuel to burn the secondary fuel in the gas phase. When attempting to achieve complete combustion using a two-stage combustion method, the combustion efficiency of the catalyst decreases significantly as the fuel flow rate increases due to pressurization, and it is still difficult to obtain a practically completed catalyst body. It's not on. <Object of the invention> Therefore, the object of the present invention is to ignite flame-retardant methane fuel at a lower temperature with a smaller catalyst capacity even under the above-mentioned actual operating conditions of a gas turbine under high pressure, thereby reducing the combustion gas temperature. It can raise the temperature to 750 to 1000℃, has durability, and has CO,
The object of the present invention is to provide a combustion catalyst system that does not substantially contain harmful components such as NOx and UHC, and to provide an effective method for using the system. <Means for solving the problem> In order to achieve this objective, the present inventors used methane, which is the most flame-retardant among combustible gases, and conducted experiments under various conditions ranging from normal pressure to high pressure. We investigated catalytic combustion. As a result, the combustion reaction of methane mainly depends on the heterogeneous reaction on the catalyst surface at the gas inlet side, that is, the low-temperature region catalyst in the front stage, while on the gas outlet side, that is, in the high-temperature region in the rear stage. It was found that the reaction mainly depends on a homogeneous reaction in the gas phase. In other words, under the same linear velocity, as the gas density and gas flow rate increase due to pressurization, the heterogeneous reaction on the catalyst surface in the front stage is controlled by diffusion due to the mass transfer of the combustion gas.
It has been found that the rate-limiting reaction occurs on the surface of the catalyst, leading to a large decrease in combustion efficiency, while the combustion reaction in the gas phase in the latter stage leads to an improvement in combustion efficiency. As a result of extensive research into a catalyst layer suitable for the combustion reaction of methane as described above, the present invention was completed. That is, the combustion catalyst system of the present invention is divided into three catalyst layers, and one layer is placed on the gas inlet side for the flow of a high pressure, high linear velocity combustible mixed gas containing methane fuel and molecular oxygen. A front catalyst layer containing palladium and platinum as active ingredients, or palladium platinum and nickel oxide as active ingredients,
Next, the catalyst system consists of a middle catalyst layer containing platinum as an active component, and finally a rear catalyst layer containing platinum and palladium as active components on the gas outlet side. Loading amount is 10 per carrier volume
It is characterized by a range of ~100g, and ignites from a relatively low temperature in the front catalyst layer, reducing the combustion gas temperature.
Each of them is optimally designed so that the temperature can be raised to 750 to 1000°C, and the temperature does not exceed 1000°C. As a result, the catalytic activity for the methane combustion reaction is greatly improved, and the two-stage combustion is able to overcome the effects of increased space velocity (reduced contact time) and high linear velocity at the inlet, which degrade combustion performance under high pressure. They discovered that this method makes it possible to achieve complete combustion, reduce the catalyst capacity and improve the combustion load factor, and make it possible to put it into practical use in actual gas turbine combustors. Furthermore, the combustion catalyst system according to the present invention will be specifically explained. Catalysts containing palladium as the main active component are known to have particularly excellent low-temperature ignition of methane, as well as excellent heat resistance at high temperatures of around 1000°C. However, when a conventional catalyst containing palladium as an active ingredient is used for the purpose of the present invention, it is exposed to a high concentration of oxygen at a temperature of 500°C or less near the entrance of the catalyst layer, so palladium is oxidized and impairs the methane ignition performance. On the other hand, in the high temperature region near the outlet of the catalyst layer, the combustion reaction by the catalyst is suppressed and the combustion gas temperature does not actually rise to a high temperature of 750℃ or higher, probably due to a change in the oxidation state of palladium. There is a drawback. In contrast, according to the present invention, the gas inlet side of the combustion catalyst system, that is, the front catalyst layer, mainly contains palladium as an active ingredient, and the presence of a small amount of platinum improves methane ignition performance by converting palladium into oxide. This prevents deterioration and allows low-temperature ignition performance to be maintained for a long period of time. It is preferable that nickel oxide is further added,
In this case, since nickel exists as an oxide, oxygen is stably supplied to palladium from the air, so the combustion gas temperature can be controlled at high linear velocity and under high pressure.
The temperature can be raised to 500 to 700°C, or up to 750°C depending on the conditions, and then the combustion reaction can be easily started in the middle catalyst layer. Furthermore, in the middle catalyst layer containing platinum as an active ingredient, the combustion activity is further improved and the temperature can be raised to a temperature in the range of 650 to 900°C. Furthermore, the gas outlet side of the combustion catalyst system, that is, the latter stage catalyst layer, contains platinum and palladium as active ingredients, and platinum further promotes combustion and brings the combustion gas to a temperature of 900 to 1000°C. becomes possible. In many cases, when the catalyst temperature is exposed to a high temperature range of 1000℃ or higher, platinum is oxidized to PtO ₂ and sublimated and scattered, but the coexistence of palladium prevents platinum from sublimating.
Combustion activity is stably maintained at a high level. As described above, the catalyst system of the present invention is characterized by a three-stage configuration that takes advantage of or combines the characteristics of each precious metal, and methane-based fuel is heated at 300 to 400°C under high pressure and high linear velocity. It ignites at low temperatures, has combustion activity to obtain a combustion gas temperature of 750 to 1000°C, and has heat resistance of 1000°C or higher. However, as mentioned above, a catalyst containing only palladium as an active ingredient does not lose its ignition performance as the combustion progresses, and due to its characteristics, the combustion gas temperature
Virtually no temperature rises above 750°C. Even a palladium-nickel oxide catalyst loses ignition performance in the same way as palladium alone. In addition, platinum alone cannot ignite methane-based combustion such as methane or natural gas at 300 to 400 degrees Celsius.
In practice, an ignition temperature of 500℃ or higher is required, but
It has excellent combustion activity, especially under high pressure and high linear velocity combustion conditions. Also,
Palladium-platinum-nickel oxide or palladium-platinum catalysts have sufficient ignition performance, but when the combustion gas temperature is lowered to 2.
The temperature cannot exceed the temperature at which secondary gas phase combustion is induced. As mentioned above, each one-stage configuration has its own drawbacks, especially under high-pressure combustion conditions.
It cannot be used as a practical catalyst and is not preferred. The amount of platinum group elements supported in the front catalyst layer and the middle catalyst layer is 20 to 100 g, preferably 30 to 80 g per carrier volume. The supporting ratio of palladium to platinum in the front catalyst layer is 1 to 25, preferably 2.
~10. In addition, when nickel oxide is added to the front catalyst layer, the amount of nickel oxide supported is suitably 10 to 150 g per carrier volume, preferably 50 to 150 g, in order to stably supply oxygen from air to palladium. It is 120g. The amount of platinum group elements supported in the latter catalyst layer is 10 to 80 g per carrier volume, preferably 20 to 50 g. When platinum and palladium coexist, the supporting ratio of palladium to platinum is
It is 0.1-10, preferably 0.2-5. The post-catalyst body may be prepared separately from a plurality of stages from the first stage to the second stage, and each catalyst may be directly connected or installed with a space provided therebetween, or it may be made into a complete catalyst as an integrated catalyst body. When prepared separately in multiple stages, even if there is a catalyst in which the amount of platinum group elements supported is less than 10 g per carrier volume, as long as the total amount of platinum group elements supported as a completed catalyst is 10 g or more. , of course, can be used. If the total amount of platinum group elements supported is less than 10g,
As the gas density and flow rate increase due to pressurization, the amount of active substance becomes insufficient relative to the number of methane molecules to be combusted. Therefore, the ignition temperature of methane is the ignition temperature of the front catalyst layer of the present invention.
The temperature is higher than that of 300 to 400°C, and a pilot burner is required for pre-combustion, and the ratio of pre-combustion in the pilot burner section for ignition increases, increasing the amount of NOx generated. Furthermore, even if it ignites, its combustion activity is low, fuel blows through frequently, and the temperature of the combustion gas does not rise sufficiently, making it difficult to cause a combustion reaction in the subsequent stage of the catalyst. In addition, the downstream catalyst also has low activity, resulting in insufficient combustion and a large amount of fuel blow-through, making complete combustion impossible and increasing the gas temperature to a temperature that induces secondary gas phase combustion. It is also very difficult to restrain them. Therefore, even if a catalyst having a total amount of platinum group elements supported of 10 g or less has high activity under normal pressure, it does not have sufficient combustion activity under pressure. On the other hand, if the total amount of platinum group elements supported exceeds 100g, although the dispersibility decreases, the combustion activity increases due to the increase in active substances, and the combustion gas temperature cannot be suppressed to below 1000℃, resulting in rapid activation. This is not preferable because it causes a decrease in the catalyst and the catalyst becomes very expensive. As the catalyst carrier, a monolith type carrier is preferable for the purpose of reducing pressure loss. Any monolith support commonly used in the field can be used, especially cordierite, mullite, α-alumina, zirconia, titania, titanium phosphate, aluminum titanate,
Heat-resistant ceramics such as petalite, spodium, aluminosilicate, magnesium silicate, zirconia-spinel, zircon-mullite, silicon carbide, silicon nitride, and kanthal,
A metal material such as Feclaroy is used. The cell size of the monolithic carrier is preferably large as long as combustion efficiency is not reduced, and each catalyst layer may have the same cell size or may be a combination of different cell sizes. A 400 cell type is used. The total catalyst layer length varies depending on the inlet linear velocity used, but is usually 50 to 50 mm due to the need to reduce pressure loss.
300mm is adopted, and the length of each layer also depends on pressure, fuel concentration,
It is optimally selected depending on usage conditions such as inlet linear speed and inlet temperature, but usually 10 to 200 mm is used for each layer. Platinum and palladium are particularly preferred as platinum group elements, but other elements such as rhodium and iridium may also be added. Furthermore, metal oxides such as nickel, cobalt, iron, and chromium, and composite oxides such as CoNiO ₂ and LaCoO ₃ also exhibit effects as active substances when used in combination with platinum group elements. These active ingredients and alumina are supported on the monolithic carrier and catalyzed. Refractory metal oxides such as silica-alumina, magnesia, titania, zirconia, and silica-magnesia can also be used. The above refractory metal oxides include alkaline earth metal oxides such as barium and strontium, lanthanum,
It is preferable to add a rare earth metal oxide such as neodymium, cerium, or praseodymium or silica oxide to stabilize the material. In particular, in the case of alumina, it is more preferable to use alumina stabilized with at least one oxide selected from the group consisting of lanthanum, cerium, samarium, neodymium, praseodymium, calcium, strontium, barium and silica. The catalyst component may be supported by coating with a refractory metal oxide and then impregnated with the active component in the form of a water-soluble salt, or by supporting or mixing the active component with the refractory metal oxide in advance. Then, it may be supported on a monolithic carrier. Examples of water-soluble salts include nitrates, sulfates, phosphates, halides, and dinitroamino salts.
Examples include palladium nitrate, palladium chloride, dinitrodiaminoplatinum, chloroplatinic acid, etc., and a carrier is impregnated with an aqueous solution of these.
1 at a temperature of 400-1000℃, preferably 600-900℃
It is obtained by baking for 24 hours, preferably 2 to 6 hours. The active ingredient, platinum, can also be supported together with the active refractory metal oxide in the form of platinum black having an average particle size of 0.01 to 5 microns. Nickel sources include nickel nitrate, nickel chloride, and nickel acetate, and nickel oxide may be used as is. The present invention can be made more effective by optimally selecting and combining these catalyst components from the inlet side to the outlet side depending on the usage conditions. The fuel used in the combustion catalyst system of the present invention is methane-based fuel, particularly natural gas containing methane as a main component and lower hydrocarbons such as ethane, propane, and butane. Furthermore, fermented methane from activated sludge treatment and low-calorie methane gas from coal gasification are also fuels that can be used in the present invention. Naturally, more flammable propane, light oil, etc. can also be used. The combustion catalyst system of the present invention is optimally incorporated into a power generation gas turbine system as described above, but can also be incorporated into a power generation boiler,
It can be advantageously incorporated into systems that efficiently recover heat and power, such as heat recovery boilers, heat recovery through after-treatment of gas from gas engines, and city gas heating. <Examples> The present invention will be explained in more detail below with reference to Examples, but the present invention is not limited to these Examples. Example 1 Diameter with 200 cells/in2 aperture
A cordierite honeycomb carrier measuring 25.4 mm and 50 mm in length was coated with a slurry of a mixture of alumina powder and nickel oxide powder containing 5% by weight of lanthanum oxide, dried, and then combusted in air at 700°C. hand,
100 g of lanthanum oxide-containing alumina and 100 g of nickel oxide were coated and supported per carrier volume. Next, this was immersed in an aqueous solution containing palladium nitrate and chloroplatinic acid, dried at 150°C,
The catalyst was calcined in air at 900° C. for 5 hours, and 50 g of palladium and 10 g of platinum were supported per carrier volume to obtain a completed catalyst. Example 2 Alumina powder containing 28.8% by weight of nickel oxide, 2% by weight of cerium oxide, and 1% by weight of strontium oxide was immersed in an aqueous solution containing palladium nitrate and chloroplatinic acid, dried, and then left in air.
24% by weight of palladium after firing at 600℃ for 3 hours.
3.9% by weight of platinum was supported. Next, this palladium and platinum-supported alumina powder slurry was coated on a mullite honeycomb carrier with a diameter of 25.4 mm and a length of 50 mm having pores of 200 cells/square inch, dried, and heated at 700°C in air.
By calcining for 5 hours, a completed catalyst was obtained in which 50 g of palladium, 8 g of platinum, and 60 g of nickel oxide were supported per carrier volume. Example 3 A slurry of alumina powder containing 5% by weight of lanthanum oxide was prepared in Example 1 on the same carrier as in Example 1.
In the same manner as above, 150 g of lanthanum oxide-containing alumina was coated and supported per unit volume. Next, in the same manner as in Example 1, 50 g of palladium and 10 g of platinum were supported per volume of the carrier to obtain a completed catalyst. Example 4 A slurry of alumina powder containing 7% by weight of lanthanum oxide and 3% by weight of neodymium oxide was added to the same carrier as in Example 1, and alumina containing lanthanum oxide and neodymium oxide was added per carrier volume in the same manner as in Example 1. As a result, 120 g/l was loaded on the coating. Next, in the same manner as in Example 1, 60 g of palladium and 30 g of platinum were supported per carrier volume to obtain a completed catalyst. Example 5 Diameter with 400 cells/in2 aperture
A slurry of alumina powder containing 8% by weight of lanthanum oxide and 2% by weight of silicon oxide was added to an aluminum titanate carrier having a size of 25.4 mm and a length of 50 mm in the same manner as in Example 1 to obtain lanthanum oxide and silicon oxide containing per carrier volume. 150g as alumina
was coated and supported. Next, using the same palladium and platinum-containing aqueous solution as in Example 1, it was calcined in air at 600°C for 5 hours.
A completed catalyst was obtained by supporting 40 g of palladium and 20 g of platinum. Example 6 The same lanthanum oxide and silicon oxide-containing alumina powder as in Example 5 was added to the same carrier as in Example 1.
150g/coating was carried. Next, this was immersed in a nitric acid aqueous solution containing dinitrodiaminoplatinum, dried, and then immersed in air.
The catalyst was calcined at 900° C. for 5 hours, and 20 g of platinum was supported per volume of the carrier to obtain a completed catalyst. Example 7 Diameter with 400 cells/in2 aperture
A slurry of alumina powder containing 4% by weight of barium oxide and 2% by weight of praseodymium oxide and platinum black powder having an average particle size of 0.2 microns were thoroughly mixed in a cordierite honeycomb carrier of 25.4 mm and 50 mm in length. After coating and drying in the air
The catalyst was calcined at 700° C. and 30 g of platinum was supported per volume of the carrier to obtain a completed catalyst. Comparative Example 1 In the same manner as in Example 1, 5 g of palladium, 1 g of platinum, and 100 g of nickel oxide were supported per volume of the carrier to obtain a completed catalyst. Comparative Example 2 In the same manner as in Example 3, 5 g of palladium and 1 g of platinum were supported per volume of the carrier to obtain a completed catalyst. Comparative Example 3 In the same manner as in Example 4, 4 g of palladium and 2 g of platinum were supported per volume of the carrier to obtain a completed catalyst. Comparative Example 4 In the same manner as in Example 6, 2 g of platinum was supported per volume of the carrier to obtain a completed catalyst. Comparative Example 5 In the same manner as in Example 4, 60 g of palladium and 150 g of platinum were supported per volume of the carrier to obtain a finished catalyst. Example 8 Using a sufficiently warmed cylindrical combustor, the gas inlet side was filled with the catalyst obtained in Example 1, then Example 6, and the gas outlet side was filled with the catalyst obtained in Example 4, and the inlet temperature was 350.
Methane containing 3% by volume methane at °C
Air mixed gas per hour under pressure of 15 atmospheres
Combustion experiments were conducted by introducing 167Nm ² (STP) and the combustion efficiency and catalyst layer outlet temperature were measured. In this case, the linear velocity at the entrance of the catalyst layer was approximately 20 m/sec (calculated at 500°C). As a result, the combustion efficiency was about 72% and the catalyst bed outlet temperature was about 850°C. Next, when the methane concentration was increased to 4.1% by volume, the combustion efficiency became 100%, and clean combustion gas containing virtually no UHC, CO, or NOx was obtained.
In this case, the temperature at a point 100mm behind the catalyst layer is approximately 1300.
℃, but the catalyst layer outlet temperature was approximately 870℃. Subsequently, a similar combustion experiment was conducted by introducing methane equivalent to 3% by volume from upstream of the catalyst bed and the remaining methane equivalent to 1.1% by volume from 30 mm behind the outlet of the catalyst bed (Experiment No. 1). As a result, the catalyst bed outlet temperature was approximately 860℃,
Clean combustion gas of approximately 1300℃ was obtained. This performance was maintained for 1000 hours. For details of the results of the combustion experiment of experiment number 1, see Table-
Shown in 1. Example 9 Using a cylindrical combustor with sufficient heat insulation, Table 1
As shown in Experiment Nos. 2 to 6, the completed catalysts obtained in Examples 1 to 7 were filled from the gas inlet side to the gas outlet side, and the following combustion experiments were conducted in the same manner as Experiment No. 1 in Example 8. The results are shown in Table 1. Comparative Example 6 In Example 8, a catalyst experiment was conducted in the same manner as in Example 9, except that the completed catalysts listed in experiment numbers 7 to 9 in Table 1 were filled, and the results are shown in Table 1. . <Effects> From this Table-1, the following effects are shown. If the catalyst according to the present invention was used (experiment numbers 1 to 6), a clean combustion gas of about 1300°C could be obtained even though the catalyst bed temperature was maintained at 1000°C or less without causing a decrease in activity. On the other hand, when the catalyst obtained in Comparative Example 1 or 2 was used on the gas inlet side, followed by Comparative Example 4, and the catalyst obtained in Comparative Example 3 was used on the gas outlet side (experiment numbers 7 to 8), the catalyst layer outlet temperature was 450 to 475°C. The temperature cannot rise to the point where secondary gas-phase combustion is induced, and the temperature at a point 100 mm behind the catalyst layer is 445 to 470, and the combustion efficiency is approximately
It was 10-13%. Furthermore, the results of Experiment No. 9 using the catalyst obtained in Comparative Example 5 as the latter stage catalyst showed that the total supported amount of palladium and platinum exceeded 100 g per carrier volume.
Although the temperature of the latter catalyst layer was 940°C, the activity of the latter catalyst layer decreased after 24 hours, and significant aggregation of platinum group elements was observed after 100 hours. 【table】

Claims (1)

[Claims] 1. 5- containing methane-based fuel and molecular oxygen.
For the flow of combustible mixed gas at a high pressure of 30 atm and a flow rate of 5 to 40 m/sec at 500°C, the gas inlet side contains palladium and platinum as active ingredients, or palladium, platinum and nickel oxide as active ingredients. The catalyst system consists of a front catalyst layer containing platinum as an active component, a middle catalyst layer containing platinum as an active component, and finally a rear catalyst layer having platinum and palladium as active components on the gas outlet side. A catalyst system for combustion of high-pressure methane fuel, characterized in that the total amount of platinum supported is in the range of 10 to 100 g per carrier volume. 2. The catalyst system according to claim 1, wherein the amount of palladium supported in the first catalyst layer is at a ratio of 1 to 25 to the amount of platinum supported. 3. The catalyst system according to claim 1, wherein the amount of palladium supported in the latter catalyst layer is at a ratio of 0.1 to 10 relative to the amount of platinum supported. 4. The catalyst system according to claim 1, wherein the active components in each catalyst are dispersed and supported on a monolithic carrier coated with alumina. 5. The alumina coating layer is stabilized by an oxide of at least one element selected from the group consisting of lanthanum, cerium, samarium, neodymium, praseodymium, calcium, strontium, barium and silicon. A catalyst system according to claim 1. 6. The catalyst system according to claim 1, wherein the catalyst system is used as a fuel combustion catalyst system for a gas turbine. 7 5~ containing methane fuel and molecular oxygen
For the flow of a combustible mixed gas at a high pressure of 30 atm and a high linear velocity of 5 to 40 m/s at 500°C, palladium and platinum are used as active ingredients on the gas inlet side, or palladium, platinum and nickel oxide are added to the gas inlet side. The catalyst system consists of a front catalyst layer containing platinum as an active component, a middle catalyst layer containing platinum as an active component, and finally a rear catalyst layer containing platinum and palladium as active components on the gas outlet side. Using a catalyst system for combustion of high-pressure methane-based fuel in which the total amount of platinum and palladium supported is in the range of 10 to 100 g per carrier volume, only a part of the methane-based fuel is catalytically combusted in the catalyst system. , a combustion method characterized by raising the temperature of combustion gas to a temperature that induces secondary gas phase combustion. 8. In the combustion method according to claim 7,
Set the combustion gas temperature at the front catalyst layer to 500 to 750.
A combustion method characterized by raising the temperature to a temperature in the range of 650 to 900°C in the middle catalyst layer and 750 to 1000°C in the latter catalyst layer. 9. The combustion method according to claim 7, characterized in that secondary fuel is further supplied to the gas heated to a temperature that induces secondary gas phase combustion to cause secondary gas phase combustion.