JP2976239B2 - Composite catalyst for high temperature combustion - Google Patents

Description

Description: FIELD OF THE INVENTION The present invention relates to a composite catalyst body for high-temperature combustion used in a high-temperature combustion apparatus for a fuel-air mixture such as a gas turbine, industrial and domestic burner.

2. Description of the Related Art Conventional technology and its problems Gas turbine cogeneration systems using natural gas as fuel and combined gas turbine power generation systems for power generation have attracted attention as means for achieving resource and energy savings because they can significantly improve efficiency. . Regarding these methods, in order to prevent environmental pollution by NOx, it is indispensable to significantly suppress NOx generation. Currently, as a method of reducing the amount of NOx in exhaust gas from gas turbines, a selective catalytic reduction method using ammonia (SC
R) has reached the stage of practical application. However, this N
Ox reduction methods have the following problems: (a) the use of ammonia, which is a dangerous substance, is essential, and (b) high initial and running costs. Have been.

For example, combustion combustion means for completely combusting a lean air-fuel mixture at a level at which NOx can be significantly reduced at a temperature equal to or higher than a temperature at which a gas turbine can be efficiently operated by catalytic oxidation and heat retention of a catalyst is a special feature. It is disclosed in JP-B-53-37485. And the catalyst used in this combustion means,
For example, it is disclosed in JP-A-57-210207 and JP-A-59-41706. In order to put a catalytic combustion system into practical use, it is most important to maintain catalytic activity for a long period of time. However, in the above-mentioned known documents, there is no disclosure or teaching about maintaining the catalytic activity for a long time.

Since then, research aimed at commercializing catalytic combustion systems has been widely conducted. As a result, it has been found that a catalyst containing noble metal palladium or platinum as a main catalytic active component shows volatility in an oxidizing atmosphere at 1000 ° C. or higher and cannot obtain stability at 1000 ° C. or higher. In addition, known low-volatile base metal oxide-based catalysts include known single oxide composite catalysts and perovskite-based catalysts.
It easily sinters at over 00 ° C and reacts with the coating material, such as alumina, to reduce active area and reactivity. doing.

Accordingly, recently, Japanese Patent Application Laid-Open Nos.
As disclosed in Japanese Patent Application Laid-Open No. 0-175925, etc., under a combustion condition in which the outlet temperature of the catalyst is set to 1000 ° C. or lower, a hybrid catalytic combustion system in which a secondary fuel is added to the downstream to perform gas phase combustion. Numerous catalysts have been proposed for use in lithography. However, in the hybrid catalytic combustion system, since the secondary combustion is performed by the gas phase reaction, the combustion temperature has to be significantly increased as compared with the system that performs only the catalytic combustion.
Generation of x is inevitable. As a result, there are drawbacks in that it is difficult to reduce the NOx generation amount, the combustor becomes large, the control system becomes complicated, and the practicability is poor.

The present inventor has reexamined the above-mentioned problems of the conventional technology in detail, and as a result, if a catalyst system capable of performing stable catalytic combustion at a temperature of about 1000 to 1300 ° C. is found, a catalyst having a high applicability will be obtained. It was concluded that the combustion system could be put to practical use. More specifically, one of the causes of the conventional catalyst gradually losing its activity at a temperature of 1000 ° C. or higher is that a honeycomb structure having an extremely small specific surface area and functioning only as a structure has a catalytically active component ( It is considered that a supported catalyst in a coated form may be used together with an alumina-based supporting material for imparting a specific surface area thereto (a noble metal or base metal oxide). In such a supported catalyst, at a temperature of 1000 ° C. or higher, the specific surface area is reduced by sintering of the alumina as a supporting material, and the active sites are covered, and the activity of the catalytically active component is reacted with the alumina and the honeycomb structure. Deterioration causes such as reduction and peeling of the catalyst coating layer occur. Furthermore, as an essential factor of catalyst activity deterioration,
In the conventional catalyst, there is a problem that the active area cannot be maintained because the catalytically active component itself has volatility or is easily sintered.

Means for Solving the Problems The present inventor has further studied and found that when a manganese-substituted layered aluminate composition having a specific composition is formed into a honeycomb shape without using an inorganic binder,
It has been found that a catalyst body that enables stable catalytic combustion at a temperature of 1000 to 1300 ° C. can be obtained.

That is, the present invention provides the following composite catalyst for high-temperature combustion.

1. A catalyst used in an apparatus for burning a fuel gas-air mixture at a high temperature, comprising: (a) palladium, lanthanum oxide and / or barium oxide on a heat-resistant honeycomb structure on an inflow side of the mixture; A first catalyst body supporting a catalyst component as a main component, and a plurality of second catalyst bodies formed of a manganese-substituted layered aluminate in a honeycomb shape in a downstream portion thereof; ) The first catalyst body contains 50 g / l or more of palladium and lanthanum oxide-containing alumina and / or
Or it carries a barium oxide-containing alumina 50~200g / l, (c) manganese substituted laminar aluminate constituting the second catalyst _{body, Sr 1-x La x Mn} y Al 12-y O _19−α (where x =
0.1 to 0.4, y = 0.5 to 2.0), each of which has a layer height of 10 to 25 mm, and (d) a specific surface area of the second catalyst body on the upstream side of 8 to 8 mm. 20 m ² / g, the downstream side hot combustion composite catalyst having a specific surface area, characterized in that a 3 to 8 m ² / g of.

2. The composite catalyst for high-temperature combustion according to item 1, wherein the amount of palladium carried on the first catalyst is 100 g / l or more per honeycomb volume.

_{3.Sr 1-x La x Mn y} Al 12-y O 19-α in the second catalyst represented by the high temperature combustion complex catalyst body according to item 1, wherein the x = 0.2.

The composite catalyst body used in the present invention comprises a first catalyst body located on the inlet side where the fuel gas-air mixture flows, and a plurality of second catalyst bodies located on the counterflow side thereof. I have. Hereinafter, each catalyst body will be described in detail.

The first catalyst body supports palladium and alumina containing lanthanum oxide and / or barium oxide as catalytically active components on a honeycomb-shaped carrier made of a heat-resistant material. The honeycomb carrier is not particularly limited as long as it has heat resistance up to about 1200 ° C., but it is mass-produced, low-cost, has a low coefficient of thermal expansion, and has excellent thermal shock resistance. Light ones are best. As the honeycomb carrier, those having an opening ratio of about 60 to 70% and the number of cells per square inch of about 100 to 200 are preferable. The first catalyst body is palladium based on the honeycomb volume.
50 g / l or more, more preferably about 100 to 200 g / l, and alumina containing lanthanum oxide and / or barium oxide is about 50 to 200 g / l, more preferably 100 to 1 g / l.
It carries about 50 g / l. Such lanthanum oxide and / or barium oxide contributes to prevention of sintering of the alumina component, and enables the catalyst body to maintain high catalytic activity for a long time. The blending amount of lanthanum oxide and / or barium oxide with respect to alumina is about 5 to 25% of the weight of alumina. NiO, MgO, Ce ₂ O ₃ or the like can be added as a co-catalyst to the first catalyst body. These co-catalysts are 20 to
It is used at a rate of about 100 g / l and exerts an effect of suppressing the activity of palladium to some extent in a temperature range of 800 ° C. or higher.

The first catalyst body supporting palladium and alumina containing lanthanum oxide and / or barium oxide can start combustion from a temperature of 500 ° C. or less under a high linear velocity applicable to a gas turbine, Demonstrates particularly excellent catalytic activity in the low-temperature region, but generally at temperatures above 800 ° C, due to the characteristics of palladium itself, the rate of oxygen uptake on the palladium surface decreases, causing a significant decrease in activity with increasing temperature .

Therefore, in the present invention, as a second catalyst which starts combustion at least at a temperature of 800 ° C. or lower, preferably 650 ° C. or lower, and exhibits catalytic activity in a temperature range of 800 ° C. or higher, the formula (1) Sr _{1- x La x Mn y Al 12-} y O 19-α (1) ( however, x = 0.1 to 0.4, more preferably 0.2 to 0.3, y
= 0.5 to 2.0) A plurality of manganese-substituted layered aluminates represented by the following formulas are formed into honeycomb shapes having different specific surface areas. Among these plural second catalyst bodies, the catalyst body close to the first catalyst body has a specific surface area of about 8 to ²⁰ m ² / g, and is excellent in a temperature range of about 650 to 1200 ° C. It exhibits catalytic activity (the second catalyst used in this low temperature range is hereinafter referred to as "second catalyst A"). If the specific surface area of the second catalyst body A is less than 8 m ² / g, the catalytic activity becomes insufficient, while if it exceeds 20 m ² / g, the strength as a molded body decreases. Such a second catalyst body A is prepared by preparing a material having a composition corresponding to the above formula (1) by an alkoxide method,
After sintering at 1100 ° C, the obtained powder was extruded into a honeycomb shape without using an inorganic binder, and 11
It can be manufactured by sintering at a temperature of 50 to 1200 ° C. The specific surface area can be set to a desired value by appropriately adjusting the molding pressure, the sintering temperature, the sintering time, and the like. As the honeycomb-shaped molded body, the opening ratio is about 60 to 70%, and the number of cells per square inch is 150 to 3%.
About 00 is preferable. It is desirable that the thickness of the second catalyst body A is about 10 to 25 mm. The material constituting the second catalyst body A has a property of a high coefficient of thermal expansion and a low resistance to thermal shock destruction.
If it exceeds mm, the thermal stress will be high and it will be easily broken. As the thickness of the second catalyst body A is smaller, the thermal stress is reduced, but if it is less than 10 mm, it becomes difficult to hold the catalyst body so as not to move in the axial direction.

Since the second catalyst body A has a large specific surface area and a high porosity, it shrinks easily at a temperature of 1200 ° C. or more and has poor heat resistance stability, so that it can be used only in a temperature range up to 1200 ° C. However, at temperatures below 1200 ° C., complete combustion of the fuel gas-air mixture is difficult at high linear velocities applicable to gas turbines. Therefore, following the second catalyst body A having the above characteristics, it has a specific surface area of about 3 to 8 m ² / g, and generates NOx in a high temperature range up to 1300 ° C. under a high linear velocity. At least one second catalyst body (hereinafter, the second catalyst body used in the high temperature range is hereinafter referred to as "second catalyst body B") exhibiting stable catalytic combustion characteristics while significantly suppressing I do. The second catalyst body B is also prepared by preparing a material having a composition corresponding to the above formula (1) by an alkoxide method and sintering the material at 1000 to 1200 ° C., and then powdering the obtained powder without using an inorganic binder. By extruding into a shape and sintering at a temperature of 1250-1300 ° C,
Can be manufactured. The specific surface area can be set to a desired value by appropriately adjusting the molding pressure, the sintering temperature, the sintering time, and the like. As the honeycomb-shaped formed body, one having an opening ratio of about 60 to 70% and about 150 to 300 cells per square inch is preferable. The specific surface area of the second catalyst body B is in the case of more than 8m ² / g, the thermal stability is lowered to the high temperature combustion conditions, while the strength of the honeycomb body is reduced, less than 3m ² / g In this case, the catalytic activity becomes too low, and the complete combustion of the fuel gas-air mixture is not performed.

In the composite catalyst according to the present invention, the interval between the plurality of catalysts is about 5 to 10 mm.

Hereinafter, the present invention will be described in more detail with reference to embodiments of the present composite catalyst body shown in the drawings.

FIG. 1 shows an outline of an apparatus for performing a performance test of the composite catalyst for high temperature combustion of the present invention under atmospheric pressure. The composite catalyst for high temperature combustion according to the present invention is represented by (7) and (9a) to (9f). In FIG. 1, the fuel gas from line (1) and the air from line (3)
The mixture is supplied to a mixing zone (5) filled with alumina balls and uniformly mixed. Natural gas,
City gas, LPG, atomized or vaporized kerosene, etc. are used. The air is preliminarily indirectly heated by the preheating device (13).

Next, the fuel gas-air mixture is brought into contact with the first catalyst body (7) supporting palladium and lanthanum oxide and / or barium oxide-containing alumina as catalytically active components on a honeycomb carrier made of a heat-resistant material. I do.

In the apparatus shown in FIG. 1, six (9a to 9f) second catalyst bodies formed of a honeycomb-shaped formed body of a manganese-substituted layered aluminate are arranged. Among these, at least the second catalyst A (9a) close to the first catalyst (7)
As described above, (9d) has a specific surface area of about 8 to ²⁰ m ² / g, and exhibits excellent catalytic activity in a temperature range of about 500 to 1200 ° C. In the apparatus shown in FIG. 1, four second catalysts A are used, but it goes without saying that at least one second catalyst A may be used.

As described above, the second catalyst body A can be used only in a temperature range up to 1200 ° C. Therefore, following the plurality of second catalysts A (9a) to (9d), they have a specific surface area of about ² to 8 m ² / g, and have a high temperature range up to 1300 ° C. and a high linear velocity. Then, at least one second catalyst body B that exhibits stable catalytic combustion characteristics while significantly suppressing the generation of NOx is arranged (two in the example shown in FIG. 1).

In the experimental apparatus for a composite catalyst for high-temperature combustion shown in FIG. 1, the combustion gas that has passed through the second catalyst B (9f) located on the most downstream side is discharged from the exhaust gas line (11) to the outside of the apparatus. You. A well-known gas measuring device is connected to the exhaust gas line (11), and the exhaust gas is sampled to continuously measure the amount of each component in the gas. For example, hydrocarbons are measured by a FID type hydrocarbon measuring device, CO and CO ₂ are measured by a non-dispersive infrared absorption measuring device, NOx is measured by a chemiluminescent NOx measuring device, and oxygen is measured by a magnetic oxygen measuring device. Can be measured.

Further, in the experimental device shown in FIG. 1, thermocouples are installed at the positions indicated by (T-1) to (T-5), respectively, and the temperature at each position in the composite catalyst is measured.

Effects of the Invention According to the present invention, the following remarkable effects are achieved.

(1) In the apparatus of the present invention, since a catalyst formed by forming a manganese-substituted layered aluminate having high-temperature heat resistance into a honeycomb shape on the downstream side is disposed, it is recognized when a conventional supported catalyst is used. There is no space loss due to the activity reduction factor and the volume of the substrate, and a high and high catalytic activity is maintained for a very long time.

(2) Inlet temperature 500 ° C or less, adiabatic theoretical temperature 1000-1300
℃, linear velocity 5 to 15m / s (500 ℃ conversion), pressure 1
Under conditions applicable to gas turbines of ~ 20ata,
Combustion of a fuel gas-air mixture is possible, and NOx in exhaust gas is significantly reduced.

(3) Since it does not rely on hybrid catalytic combustion, it is possible to make a compact device, which is excellent in practicality.

(4) Since a palladium-supported catalyst having the highest catalytic activity is arranged in front of the composite catalyst, not only LPG and kerosene, which are easily oxidized as catalysts, but also it is said that catalytic oxidation is the most difficult. It is also suitable for burning natural gas, city gas, etc. containing methane as a main component.

(5) In order to cope with a further increase in the temperature of the gas turbine, it is of course possible to add a secondary fuel to the downstream side of the device of the present invention and perform hybrid catalytic combustion. In this case, since the exhaust gas from the apparatus of the present invention has already been heated to a high temperature of about 1000 to 1300 ° C.,
Even with a small amount of secondary fuel, gas phase combustion can be easily stabilized,
A hybrid catalytic combustion system with low NOx generation is constructed.

Examples Examples and comparative examples are shown below to further clarify the features of the present invention.

Examples 1 to 7 <Preparation of Catalyst> [Example 1] A cordierite honeycomb carrier having 200 cells per square inch, an opening ratio of 69%, and a thickness of 20 mm was coated with an average particle size of 1 mm.
8.3% by weight of μm palladium powder and lanthanum oxide
After coating the mixed sol containing the contained alumina powder, the mixture was heat-treated at 900 ° C. for 3 hours to prepare a palladium-supported honeycomb catalyst body (first catalyst body). The supported amounts of palladium and lanthanum oxide-alumina were 130 g / l and 109 g / l, respectively, per apparent volume of the honeycomb.

After dissolving aluminum isopropoxide and metal strontium in isopropyl alcohol under a nitrogen atmosphere at 80 ° C. for 5 hours, a mixed aqueous solution containing lanthanum acetate and manganese acetate is added dropwise to the obtained solution to perform hydrolysis. Was performed. After aging for 12 hours, the obtained suspension was dried at 80 ° C under reduced pressure, calcined at 500 ° C, and dried at 1100 ° C for 5 hours.
By calcining for a time, a manganese-substituted hexaaluminate crystal powder represented by the following formula Sr _0.8 La _0.2 MnAl ₁₁ O _19-α was obtained. Next, water and an organic sintering aid were added to the obtained crystal powder, kneaded sufficiently, and extruded into a honeycomb shape. After drying the obtained molded body, the obtained molded body was sintered at 1200 ° C. for 5 hours or at 1300 ° C. for 5 hours to prepare a second catalyst body A and a second catalyst body B, respectively. These catalyst bodies had an opening ratio of 65%, 300 cells per square inch, a diameter of 50 mm and a thickness of 20 mm.

The BET specific surface area of the second catalyst A was 12.2 m ² / g, and the BET specific surface area of the second catalyst B was 7.8 m ² / g.

The catalyst bodies obtained as described above were combined as described below to obtain a combustion catalyst used in the apparatus of the present invention.

First catalyst body: 1 stage Second catalyst body A: 4 stages Second catalyst body B: 2 stages [Example 2] The amount of palladium and lanthanum oxide-alumina supported on a cordierite honeycomb carrier was determined by the following method. A combustion catalyst was prepared in the same manner as in Example 1 except that the apparent volume per unit was 60 g / l and 60 g / l, respectively.

[Example 3] The loading amounts of palladium and barium oxide-alumina (BaO content: 20% by weight) on a cordierite honeycomb carrier were respectively determined per apparent volume of the honeycomb carrier.
A combustion catalyst was prepared in the same manner as in Example 1 except that the amounts were 60 g / l and 60 g / l.

Example 4 The second catalyst A (BET specific surface area 10.4 m ² / g) and the second catalyst B (BET specific surface area 5.2 m ² ) in which the composition of the manganese-substituted hexaaluminate was changed as follows: / g), except that combustion catalyst was prepared in the same manner as in Example 1.

Sr _0.9 La _0.1 MnAl ₁₁ O _19-α [Example 5] Second catalyst A (BET specific surface area = 10.7 m ² / g) in which the composition of manganese-substituted hexaaluminate was changed as follows:
A combustion catalyst was prepared in the same manner as in Example 1 except that the second catalyst B (BET specific surface area = 5.6 m ² / g) was used.

Sr _0.6 La _0.4 MnAl ₁₁ O _19-α [Example 6] Second catalyst body A (BET specific surface area = 18.5 m ² / g) in which the composition of manganese-substituted hexaaluminate was changed as follows:
A combustion catalyst was prepared in the same manner as in Example 1 except that the second catalyst B (BET specific surface area = 12.0 m ² / g) was used.

Sr _0.8 La _0.2 Mn _0.5 Al _11.5 O _19-α [Example 7] The second catalyst A (BET specific surface area 8.0 m ² / g) in which the composition of manganese-substituted hexaaluminate was changed as follows, and A combustion catalyst was prepared in the same manner as in Example 1 except that the second catalyst B (BET specific surface area: 3.1 m ² / g) was used.

Sr _0.8 La _0.2 Mn _2.0 Al ₁₀ O _19-α <Combustion test device> As the combustion test device under atmospheric pressure, the first
The type shown in the figure was used.

Further, as a combustion test device under a pressure close to that of a practical machine, the one shown in FIG. 2 was used. In the apparatus shown in FIG. 2, the fuel gas from the line (101) is supplied with air from the line (103) and the electric heater (1).
07) mixed with the air from the line (105) preheated, and in the preheating baking section (I) equipped with a diffusion combustion type burner, the air is heated to the catalyst inlet temperature. Next, in the premixing section (II), after the fuel gas from the line (109) is mixed with the preheated air, the catalytic combustion section (I
II), and catalytic combustion is performed in the same manner as in the apparatus shown in FIG. Exhaust gas is supplied on line (11
From 1), it is taken out of the system via a cooler and a pressure regulating valve (not shown). What is indicated by (113) is a viewing window. Exhaust gas sampling and analysis is the first
This is performed in the same manner as in the case of the apparatus shown in the figure. Also,
The thermocouples represented by (T-1) to (T-5) can be used to measure the temperature at each position in the high-temperature combustion catalyst device,
This is similar to the case of the device shown in FIG.

<Combustion test> Using natural gas (sulfur content 7mg / Nm) supplied as fuel,
Combustion was performed at a catalyst inlet temperature of 500 ° C and a theoretical adiabatic combustion temperature of 1,260 to 1,090 ° C under substantially atmospheric pressure.

The results are shown in FIG. In any of the first to seventh embodiments, as shown in FIG.
At a linear velocity of about m / sec (based on the superficial tower), complete combustion of 99% or more was shown.

FIG. 4 shows the temperature distribution of the catalyst layer at a linear velocity of 10 m / sec. Outlet temperature of the palladium-supported catalyst layer (T-
2) is 750 ° C. or lower, and the temperature of the manganese-substituted hexaaluminate catalyst is continuously increased at the outlet of the catalyst layer (T-3) made of manganese-substituted hexaaluminate in the subsequent stream. It is clear that the activity is exhibited from a temperature of 800 ° C. or less at which the activity of the palladium catalyst is predicted to decrease.

FIG. 5 shows the combustion performance when the theoretical adiabatic combustion temperature was 1260 ° C. and the inlet temperature was changed to 500 ° C., 450 ° C. and 400 ° C. At all inlet temperatures, a combustion efficiency of almost 100% is achieved at the linear speed required for the turbine of 10 m / sec or more.

Table 1 shows changes in the BET specific surface area of each catalyst when burning was continued for 1000 hours using the catalyst of Example 1.

Although the specific surface area of the palladium catalyst (first catalyst body) is slightly reduced, it still retains a high specific surface area.
On the other hand, in the case of the manganese-substituted hexaaluminate catalyst (second catalysts A and B), the decrease in the specific surface area is extremely small.

Also, none of the removed catalysts showed any signs of destruction such as cracks.

From these results, it is clear that the catalyst system according to the present invention has sufficient durability for practical use.

Further, for each of the catalysts of Examples 1 to 7, when continuous combustion was performed for 240 hours under the conditions of an inlet temperature of 500 ° C., a theoretical adiabatic combustion temperature of 1300 ° C., and a linear velocity of 12 m / sec, the change in activity and the temperature of the catalyst layer during that time No change was noted. Further, the catalyst after the continuous combustion did not crack nor showed any sign of destruction. The NOx generation concentration in these tests was 0.1 ppm or less. further,
Table 2 shows that, using the apparatus shown in FIG. 2 and the catalyst of Example 1, the introduced air temperature was 300 ° C., the catalyst inlet temperature was 500 ° C., the theoretical adiabatic combustion temperature was 1160 ° C., and the linear velocity (inlet standard) was 10 m / sec. 4 shows the combustion performance when the pressure is changed in the range of 2 to 4 ata under the given conditions.

From the results shown in Table 2, it is clear that the combustion amount increases in response to the increase in the pressure, but the combustion performance follows well. In this test, in order to adjust the temperature of the introduced air from 300 ° C to the catalyst inlet temperature of 500 ° C,
Since a gas-phase combustion burner is used, NOx is generated in that part, but 35 ppm is achieved in terms of 0% oxygen.

Comparative Examples 1 to 4 <Preparation of Catalyst> [Comparative Example 1] Except that the loading amounts of palladium and barium oxide-alumina on a cordierite honeycomb carrier were respectively 40 g / l and 40 g / l per apparent volume of the honeycomb carrier. Produced a combustion catalyst in the same manner as in Example 1.

Comparative Example 2 A combustion catalyst was prepared in the same manner as in Example 1 except that six stages of the second catalyst B used in Example 1 were used.

Comparative Example 3 A combustion catalyst was prepared in the same manner as in Example 1 except that the thicknesses and the number of stages of the second catalyst bodies A and B used in Example 1 were changed as follows.

First catalyst body: 20 mm thickness, one stage Second catalyst body A: 30 mm thickness, two stages Second catalyst body B: 40 mm thickness, one stage [Comparative Example 4] Without using a lanthanum compound A catalyst (specific surface area: 2.8 m ² / g) was prepared from a manganese-substituted hexaaluminate composition represented by the following formula, and this was used as a second catalyst B
A combustion catalyst was prepared in the same manner as in Example 1 except that the catalyst was used instead of.

SrMn ₃ Al ₉ O _19-α <Combustion Test> The results of the combustion test performed in the same manner as in Example 1 are as follows.

[Comparative Example 1] The initial performance was not different from that of Example 1. However, inlet temperature 500 ° C, theoretical adiabatic combustion temperature 1260 ° C,
After continuous burning at a linear velocity of 10 m / sec, the outlet temperature of the palladium catalyst began to gradually decrease after 100 hours, and at the same time, the temperature of the manganese-substituted hexaaluminate catalyst also decreased.
After 0 hour, the combustion efficiency dropped to 90%.

[Comparative Example 2] A combustion test was performed in the same manner as in Example 1. In the case of this catalyst, the theoretical adiabatic combustion temperature was 1300 ° C, and the linear velocity was 10 m / m2.
Even in seconds, the combustion efficiency was only 90%.

[Comparative Example 3] The initial performance was not different from that of Example 1. In addition, inlet temperature 500 ° C, theoretical adiabatic combustion temperature 1300 ° C, linear velocity 1
When burning continuously at 2 m / sec for 240 hours, no change was observed in the combustion performance.

However, it was found that the manganese-substituted hexaaluminate catalysts after the completion of combustion all had cracks in the circumferential direction, and the strength was remarkably reduced, so that they could not be put to practical use.

[Comparative Example 4] A combustion test was carried out in the same manner as in Example 1. In the case of this catalyst, the theoretical adiabatic combustion temperature was 1300 ° C, and the linear velocity was 10 m / m.
Even in seconds, the combustion efficiency was only 90%.

[Brief description of the drawings]

FIG. 1 is a cross-sectional view showing an outline of an example of an apparatus for measuring the performance of a composite catalyst for high-temperature combustion under atmospheric pressure used in an embodiment of the present invention. FIG. 2 is a cross-sectional view showing an outline of an example of an apparatus for measuring the performance of the composite catalyst for high temperature combustion under pressure used in the embodiment of the present invention. FIG. 3 is a graph showing the results of a combustion test (the relationship between linear velocity and combustion efficiency) in the example of the present application. FIG. 4 is a graph showing a result of a combustion test (a relationship between a catalyst position and a catalyst temperature) in the embodiment of the present invention. FIG. 5 shows that the theoretical adiabatic combustion temperature = 12 in the embodiment of the present invention.
6 is a graph showing combustion performance when the inlet temperature was changed to 500 ° C., 450 ° C., and 400 ° C. when the temperature was 60 ° C. (1) Fuel gas supply line (3) Air supply line (7) First catalyst (9a) to (9b) Second catalyst A (9c) to (9f) … Second catalyst B (101)… fuel gas supply line (103), (105)… air supply line (109)… fuel gas supply line (113)… view window (I)… Combustion section (II): Premixing section (III): Catalytic combustion section

──────────────────────────────────────────────────続 き Continuation of the front page (72) Inventor Shinichi Adachi 4-1-2, Hirano-cho, Chuo-ku, Osaka-shi, Osaka Inside Osaka Gas Co., Ltd. (72) Inventor Takayuki Inoue 4-chome, Hirano-cho, Chuo-ku, Osaka-shi, Osaka 1-2-2 Osaka Gas Co., Ltd. (72) Inventor Toshio Matsuhisa 4-8-23, Hikoshimasakomachi, Shimonoseki City, Yamaguchi Prefecture (72) Inventor Mamoru Aoki 2-26-16, Yokoo, Suma-ku, Kobe City, Hyogo Prefecture (72) ) Inventor Fumika Toda 731-1 Tehiro, Kamakura City, Kanagawa Prefecture (56) References JP-A-1-139911 (JP, A) JP-A-1-210031 (JP, A) (58) Fields investigated (Int. Cl. ⁶ , DB name) B01J 21/00-38/74

Claims (3)

(57) [Claims] 1. A catalyst used in an apparatus for burning a fuel gas-air mixture at a high temperature, comprising: (a) a palladium, lanthanum oxide and / or barium oxide on a heat-resistant honeycomb structure on an inlet side of the mixture; And a plurality of second catalyst bodies in which a manganese-substituted layered aluminate is formed into a honeycomb shape in a downstream portion thereof. (B) the first catalyst body contains 50 g / l or more of palladium and lanthanum oxide-containing alumina and / or
Or it carries a barium oxide-containing alumina 50~200g / l, (c) manganese substituted laminar aluminate constituting the second catalyst _{body, Sr 1-x La x Mn} y Al 12-y O _19−α (where x =
0.1 to 0.4, y = 0.5 to 2.0), each of which has a layer height of 10 to 25 mm, and (d) a specific surface area of the second catalyst body on the upstream side of 8 to 8 mm. 20 m ² / g, the downstream side hot combustion composite catalyst having a specific surface area, characterized in that a 3 to 8 m ² / g of. 2. The composite catalyst for high-temperature combustion according to claim 1, wherein the amount of palladium carried by the first catalyst is 100 g / l or more per honeycomb volume. Wherein _{Sr 1-x La x Mn y} Al 12-y O 19-α in the second catalyst represented by the high temperature combustion complex catalyst body according to claim 1 which is x = 0.2.