JPH0545295B2 - - 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. Oxides (hereinafter referred to as NOx), carbon monoxide (hereinafter referred to as CO), unburned hydrocarbons (hereinafter referred to as UHC)
This invention relates to a combustion catalyst system for obtaining a clean combustion gas that does not substantially contain harmful components such as) and using its calorific value as various primary energy sources, especially for use in gas turbines for power generation, and a combustion method using the same. It is something. <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. In addition, 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 1000 to 1300 degrees Celsius, and to improve the efficiency of gas turbines, there is a trend towards 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 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 that of the catalyst layer, there is no need to raise the temperature higher 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 that there is 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 gas phase combustion may be performed. In this case, it is possible to avoid setting the temperature of the catalyst layer higher than necessary, and it is possible to avoid deterioration and damage to the catalyst, which is more preferable. The temperature required to induce secondary gas phase combustion here 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 some cases, high temperatures of 750 to 1000°C are required, although this varies depending on the conditions of use. 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 inlet 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 contact layer, or if necessary, the secondary fuel is introduced and added to the remaining unburned fuel, and the secondary fuel is burned 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. Not yet. <Objective of the present invention> Therefore, the object of the present invention is to ignite flame-retardant methane-based 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 and high linear velocity. , combustion gas temperature 750~1000℃
It is durable and can be raised to temperatures of
The object of the present invention is to provide a combustion catalyst system that does not substantially contain harmful components such as CO, NOx, and UHC, and to provide an effective method for using the system. <Means for Solving the Problems> In order to achieve this objective, the present inventors used methane, which is the most flame-retardant among flammable gases, and conducted contact under various conditions ranging from normal pressure to high pressure. We discussed combustion. As a result, the combustion reaction of methane mainly depends on the heterogeneous reaction on the catalyst surface in the low-temperature region catalyst on the gas inlet side, that is, in the first stage, while on the gas outlet side, that is, in the high-temperature region in the second stage. , we obtained the knowledge that it 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
The rate of combustion changes from diffusion-limited by mass transfer of fuel gas to rate-limited by reaction on the catalyst surface, leading to a significant decrease in combustion efficiency.On the other hand, the combustion reaction in the gas phase in the latter stage improves combustion efficiency. I found that it was inviting. As a result of extensive research into catalysts 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 multiple catalyst layers, and palladium is placed on the gas inlet side for the flow of a flammable mixed gas at high pressure and high linear velocity consisting of methane fuel and molecular oxygen-containing gas. , a front catalyst layer containing platinum and nickel oxide as active ingredients, then a middle catalyst layer containing palladium and platinum as active ingredients, and finally a gas outlet side with platinum as active ingredients, or platinum and palladium as active ingredients. It consists of a catalyst system in which a rear stage catalyst layer is combined, and is characterized in that the total amount of palladium and platinum supported on the catalyst system is 10 to 100 g per carrier volume, Ignition and increase combustion gas temperature
Each of these 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 has been significantly improved, and the two-stage combustion method has been used to counteract the effects of increased space velocity (reduced contact time) and high linear velocity at the inlet, which cause a decrease in combustion performance under pressure. They discovered that complete combustion can be achieved, the catalyst capacity can be reduced and the combustion load rate can be improved, and practical application to actual gas turbine combustors is possible. 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, the palladium is oxidized and loses its methane ignition performance because it is exposed to high concentrations of oxygen at temperatures below 500°C near the entrance of the catalyst layer. On the other hand, in the high temperature region near the outlet of the catalyst layer, the combustion reaction by the catalyst is suppressed, presumably due to changes in the oxidation state of palladium, and the combustion gas temperature does not actually rise above 750℃. There are drawbacks. On the other hand, according to the present invention, the gas inlet side of the combustion catalyst system, that is, the front stage catalyst layer, mainly contains palladium as an active ingredient, and platinum and nickel oxide are further added as active ingredients. In other words, the presence of a small amount of platinum prevents the deterioration of methane ignition performance due to the formation of palladium oxides, making it possible to maintain low-temperature ignition performance over a long period of time, and the presence of platinum as nickel oxide stabilizes palladium. Since oxygen is supplied from the air, the temperature of the combustion gas is raised to 600-800℃ under high pressure and high linear velocity, which then facilitates the combustion reaction in the middle catalyst layer and the rear catalyst layer. It can be started by Next, the middle catalyst layer also mainly contains palladium and platinum as active ingredients. The presence of platinum prevents the deterioration of methane combustion performance due to the formation of palladium into oxides, and the combustion gas temperature can be raised to 650 to 900°C under high pressure and high linear velocity. Additionally, nickel may exist as an oxide in this middle catalyst layer, in which case oxygen can be stably supplied to palladium from air, and the subsequent combustion reaction in the subsequent catalyst layer can be easily started. Wear. On the other hand, the gas outlet side of the combustion catalyst system, that is, the latter stage catalyst layer, mainly contains platinum as an active ingredient, and platinum further promotes combustion and brings the combustion gas to a temperature range of 800 to 1000°C. becomes possible. When attempting to completely burn high-pressure methane-based fuel in the catalyst layer, the catalyst temperature often reaches a high temperature of 1000°C or higher, and platinum is oxidized to become PtO ₂ and is sublimated and scattered. Therefore, it is necessary to coexist with palladium to prevent sublimation and scattering of platinum, and a catalyst containing platinum and palladium as active components is used.
The catalyst temperature can be suppressed to 1000°C or less, and the effect of sublimation and scattering of platinum on the active components is reduced. It is also possible to use As described above, the catalyst system according to 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 a low temperature of 300 to 400°C under high pressure and high linear velocity. It has the combustion activity to ignite and 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 the combustion gas temperature is actually 750°C.
The drawback is that it cannot rise to higher temperatures. Catalysts containing only platinum as an active ingredient have excellent combustion activity even under high pressure and high linear velocity fuel conditions when the fuel is methane or methane-based fuel such as natural gas, but they cannot ignite at 300 to 400°C. , practically 500
This is not preferable since it requires an ignition temperature of ℃ or higher. In addition, palladium-platinum-nickel oxide or palladium-platinum catalysts have sufficient ignition performance, but the temperature of the combustion gas must be raised to a temperature higher than that at which secondary gas phase combustion is induced under high pressure and high linear velocity combustion conditions. It is not possible. As described above, each of the one-stage configurations has drawbacks and cannot be used as a practical catalyst, especially under high-pressure combustion conditions, and is therefore undesirable. Front stage catalyst (front stage catalyst layer and middle stage catalyst layer)
The amount of platinum group elements supported is 20 to 1 per carrier volume.
100 g, preferably 30 to 60 g, and the loading ratio of palladium to platinum is 1 to 25, preferably 2 to 10. The amount of nickel oxide supported is suitably 10 to 150 g per carrier volume, preferably 50 to 120 g, in order to stably supply oxygen from air to palladium. The amount of platinum group elements supported in the catalyst in the latter stage is 10 to 80 g per carrier volume.
Preferably, when platinum and palladium coexist in amounts of 20 to 50 g, the loading ratio of palladium to platinum is
It is 0.1-10, preferably 0.2-5. The 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, or it may be 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 10 g, the amount of active substance will be insufficient relative to the number of methane molecules to be combusted as the gas density and flow rate increase due to pressurization. Therefore, the ignition temperature of methane is the ignition temperature of the catalyst in the front stage 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 blow-through occurs 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, since the downstream catalyst also has low activity, combustion is insufficient and fuel blow-by occurs very frequently, making it extremely difficult to raise the gas temperature to a temperature that induces secondary gas phase combustion. Therefore, even if a catalyst having a total supported amount of platinum group elements 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. The amount of nickel oxide supported per 1 carrier volume
If it is less than 10g, the combustion activity of the front stage catalyst will not be fully demonstrated due to insufficient supply of oxygen from the air to palladium, and if it exceeds 150g, dispersibility will be poor, leading to a decrease in combustion activity. It is. 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. As a method of supporting the catalyst component, the catalyst may be coated with a refractory metal oxide and then impregnated with the active component in the form of a water-soluble salt, or the active component may be supported or mixed 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 dinitrodiamino salts. Examples include palladium nitrate, palladium chloride, dinitrodiaminoplatinum, chloroplatinic acid, etc. A carrier is impregnated with an aqueous solution of these and heated at a temperature of 400 to 1000°C, preferably 600 to 900°C, for 1 to 24 hours. , preferably by baking for 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 becomes even 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 mixed slurry of alumina powder and nickel oxide powder containing 5% by weight of lanthanum oxide, dried, and fired at 700°C in air to form a carrier. As alumina containing lanthanum oxide per volume
100g of nickel oxide was coated and supported. 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 38.8% 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 80 g of nickel oxide were supported per carrier volume. Example 3 The same carrier as in Example 1 was coated with a mixed slurry of alumina powder and nickel oxide powder containing 5% by weight of cerium oxide, and then coated in air.
By firing at 600℃, 120g of cerium oxide-containing alumina powder per carrier volume,
80g of nickel oxide was coated and supported. Next, this was immersed in an aqueous solution containing palladium nitrate, dried, and then calcined in air at 800°C for 5 hours to give 20g of palladium per carrier volume.
A completed catalyst was obtained by supporting the 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 the carrier volume was 1.
120 g of lanthanum oxide and neodymium oxide-containing alumina were coated and supported on each. 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 A slurry of alumina powder containing 8% by weight of lanthanum oxide and 2% by weight of silicon oxide was added to the same carrier as in Example 1 in the same manner as in Example 1 to obtain a slurry containing lanthanum oxide and silicon oxide per carrier volume. 150g of alumina was coated and supported. Next, in the same manner as in Example 1, 40 g of palladium and 20 g of platinum were supported per volume of the carrier to obtain a completed catalyst. 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.
180g/coating was carried. Next, this was immersed in a nitric acid aqueous solution containing dinitrodiaminoplatinum, dried, and then heated in air at 1100 °C.
The catalyst was calcined at ℃ for 10 hours, and 20 g of platinum was supported per volume of the carrier to obtain a completed catalyst. Example 7 Diameter with 100 cells/in2 aperture
A 25.4 mm x 50 mm long aluminum titanate honeycomb carrier was coated with a slurry of alumina powder containing 4% by weight barium oxide and 2% by weight praseodymium oxide and platinum black powder having an average particle size of 0.2 microns. After treatment and drying, it was calcined in air at 700°C for 5 hours to reduce the carrier volume to 1
A completed catalyst was obtained by supporting 30g of platinum. Comparative Example 1 In the same manner as in Example 1, 5 g of palladium and 1 g of platinum were supported per volume of the carrier to obtain a completed catalyst. Comparative Example 2 In the same manner as in Example 3, 2 g of palladium and 80 g of nickel oxide were supported per volume of the carrier to obtain a completed catalyst. Comparative Example 3 Diameter with 400 cells/in2 aperture
A cordierite honeycomb carrier of 25.4 mm and length of 50 mm was coated with a slurry of alumina powder containing 5% by weight of lanthanum oxide in the same manner as in Example 1, and 100 g of lanthanum oxide-containing alumina was supported per carrier volume. I forced it. Next, the catalyst was immersed in an aqueous solution containing palladium nitrate, and 10 g of palladium was supported per volume of the carrier in the same manner as in Example 3 to obtain a completed catalyst. Comparative Example 4 In the same manner as in Example 5, 2 g of platinum and 4 g of palladium were supported per volume of the carrier to obtain a completed catalyst. Comparative Example 5 In the same manner as in Example 7, 3 g of platinum was supported per volume of the carrier to obtain a finished catalyst. Comparative Example 6 In the same manner as in Example 7, 100 g of platinum was supported per volume of the carrier to obtain a finished catalyst. Example 9 Using a sufficiently warmed cylindrical combustor, the gas inlet side was filled with the combination of catalysts listed in Experiment No. 1 in Table 1, and the inlet temperature was 350°C from the upstream of the catalyst layer.
, a methane-air mixed gas containing methane equivalent to 3% by volume was introduced at 167Nm ³ (STP) per hour under a pressure of 15ata, and the remaining methane equivalent to 1.1% by volume was introduced from 30mm behind the catalyst layer. and conducted combustion experiments. In addition, for this performance evaluation, 1000
It continued to be maintained over time. The results are shown in Table 1, and when using the catalyst according to the present invention, clean combustion gas of about 1300°C can be obtained even though the catalyst bed temperature is maintained at 1000°C or less, which does not cause a decrease in activity. On the other hand, when the catalyst obtained in Comparative Example 1 and then Comparative Example 2 was used on the gas inlet side, and the catalyst obtained in Comparative Example 5 was used on the gas outlet side (experiment number 5), the catalyst layer outlet temperature was 490°C and the secondary gas phase The temperature cannot rise to the point where combustion is induced, and the temperature at a point 100mm behind the catalyst layer is 480.
The combustion efficiency was also approximately 15% at ℃. As a result of experiment number 8 using the catalyst obtained in Example 3 in the middle catalyst layer, the total supported amount of palladium and platinum was less than 10 g per carrier volume, so the combustion activity was poor and the combustion efficiency was 41%. It was hot. In addition, the results of experiment number 9, in which the catalyst obtained in Example 4 was used as the pre-catalyst, also resulted in a catalyst that did not support nickel oxide, so the temperature at the outlet of the catalyst layer was
The temperature is 720℃, and some two-gas phase combustion is induced.
The point temperature 100mm behind was 980℃ and the combustion efficiency was 66%. Furthermore, the results of experiment number 10 using the catalyst obtained in Comparative Example 6 as the rear stage catalyst showed that the total supported amount of palladium and platinum exceeded 100 per carrier volume, and the rear stage catalyst layer temperature exceeded 1030°C and 1000°C. about 50
The activity decreased after a certain period of time, and the latter stage catalyst was deactivated after 300 hours. 【table】

Claims (1)

[Claims] 1. For a flow of a combustible mixed gas consisting of methane fuel and molecular oxygen-containing gas at a high pressure of 5 to 30 atmospheres and a high linear velocity of 5 to 40 m/sec at 500°C, the gas A first catalyst layer containing palladium, platinum, and nickel oxide as active components on the inlet side, then a middle catalyst layer containing palladium and platinum as active components, and finally a catalyst layer containing platinum as active components or platinum and palladium on the gas outlet side. A high-pressure methane-based fuel comprising a catalyst system in combination with a latter-stage catalyst layer as an active ingredient, and characterized in that the total amount of palladium and platinum supported on the catalyst system is 10 to 100 g per carrier volume. catalyst system. 2. The catalyst system according to claim 1, wherein the amount of palladium supported in the first catalyst layer and the middle 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 when platinum and palladium are used as active components in the latter catalyst layer, the amount of palladium supported 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 each active component is dispersedly supported on a monolithic carrier coated with alumina. 5. Claim 1, wherein the alumina coating layer is stabilized with at least one oxide selected from the group consisting of lanthanum, cerium, samarium, neodymium, praseodymium, calcium, strontium, barium, and silica. catalyst system. 6. The catalyst system according to claim 1, wherein the catalyst system is a catalyst system for fuel combustion in a gas turbine. 7 Palladium, platinum, and A first catalyst layer containing nickel oxide as an active component, then a middle catalyst layer containing palladium and platinum as active components, and finally a second catalyst layer on the gas outlet side containing platinum as an active component or platinum and palladium as active components. A catalyst system for combustion of high-pressure methane fuel is used, in which the total amount of platinum and palladium supported on the catalyst system is 10 to 100 g per carrier volume. , a combustion method characterized by catalytically burning only a portion of the methane-based fuel to raise the temperature of the combustion gas to a temperature at which secondary gas phase combustion is induced. 8. In the combustion method according to claim 7,
The combustion gas temperature in the front catalyst layer is 600℃ to 800℃.
A combustion method characterized by raising the temperature to 650°C to 900°C in the middle catalyst layer and 800°C to 1000°C in the latter catalyst layer. 9. Claim 7, characterized in that secondary fuel gas is further supplied to the gas heated to a temperature that induces secondary gas phase combustion to cause secondary gas phase combustion.
Burning method described.