JPH05309275A - Hydrocarbon combustion catalyst - Google Patents

Abstract

PURPOSE:To obtain a catalyst which has high activity at a low temp. and improves the thermal efficiency by depositing a metal selected from Pd, Rh and Pt, preferably Pd on a moldenide type zeolite carrier which has a high SiO2/Al2O3 mol ratio. CONSTITUTION:The metal selected from Pd, Rh and Pt, preferably Pd is deposited on the moldenide type zeolite carrier which has a high SiO2/Al2O3 ratio (e.g. mol ratio of 210). Thus, when it is applied to a trace amount of hydrocarbon <=about 5000ppm, preferably about 3000ppm, especially gas, etc., incorporating methane, preferably e.g. combustion exhaust gas incorporating methane, etc., preferably e.g. combustion exhaust gas, etc., of fuel, in which especially steam coexists, and a trace amount of hydrocarbon of <=about 5000ppm, preferably about 3000ppm, especially gas, etc., incorporating methane, the hydrocarbon, especially methane be efficiently burned at an extremely lower temp.

Description

Detailed Description of the Invention

[0001]

FIELD OF THE INVENTION The present invention relates to a catalyst for burning hydrocarbons, especially methane.

[0002]

2. Description of the Related Art Conventionally, for example, "Fuel Association Magazine" Vol. 58, No. 625 (1979), 422-4.
On page 31, for 1% methane-air gas, a palladium-alumina catalyst is preferable as a catalyst for its combustion. For example, in the case of 0.5% Pd-alumina, the methane conversion rate at 350 ° C is 20% and the combustion start temperature is 210 ° C. Et al (Mez
aki et al. ) Report, 4% methane air gas, Malinsky that palladium-alumina catalyst is excellent as a catalyst for its combustion (Malinsky)
And Firth et al.'S report that alumina-supported iridium catalysts or zeolite-supported palladium catalysts have high activity as methane combustion catalysts. In the above conventional technology,
Although it has been reported to use zeolite as a carrier of a hydrocarbon combustion catalyst, there is no specific description about using a mordenite type zeolite carrier,
Further, although the case of using 1 to 4% methane-air gas is described, a hydrocarbon combustion catalyst, for example, a combustion exhaust gas of fuel, has a hydrocarbon content of 300.
It is needless to say that the case where a gas having a trace amount of about 0 ppm and coexisting with water vapor is used is about 5000 ppm or less, preferably 3000.
There is no specific description about the case of using a gas containing a trace amount of hydrocarbons of about ppm, especially methane.
On the other hand, in the case of the combustion exhaust gas, waste heat is sufficiently recovered, and its exhaust temperature is usually 200 to 300 ° C., for example, a small amount of hydrocarbon contained in the combustion exhaust gas, Especially when burning and removing methane, 2
Combustion at a low temperature of about 00 to 300 ° C. is preferable because it can reduce the heating energy required for it, and development of a hydrocarbon combustion catalyst that is highly active at low temperatures is desired. In the present invention, a gas containing a trace amount of hydrocarbons, especially methane, of about 5000 ppm or less, preferably about 3000 ppm, particularly methane, etc., preferably in the presence of water vapor, such as combustion exhaust gas of fuel,
When applied to a trace amount of hydrocarbons of less than or equal to ppm, preferably about 3000 ppm, particularly a gas containing methane, etc., the hydrocarbon is highly active at low temperatures and is advantageous in applications such as burners, combustors, and exhaust gas treatment due to thermal efficiency. In particular, the object is to provide a catalyst for methane combustion.

[0003]

The present invention is directed to high SiO ₂
A catalyst for hydrocarbon combustion, which comprises a mordenite type zeolite carrier having a molar ratio of / Al ₂ O ₃ and a metal selected from palladium, rhodium and platinum, preferably palladium.

High SiO used as a carrier for the catalyst of the present invention
_As a mordenite type zeolite having a ₂ / Al ₂ O ₃ molar ratio, manufactured by Tosoh Corporation, product name HSZ-690HOD
(SiO ₂ / Al ₂ O ₃ molar ratio = 210) and the like.

Palladium, rhodium and platinum can be mentioned as examples of the metal supported on the above-mentioned carrier of the catalyst of the present invention. Of these, palladium is preferable because it has high activity at low temperatures and excellent low temperature activity. In the catalyst of the present invention, the amount of supported metal varies somewhat depending on its type, but in the case of palladium, it is usually 0.0
It is 5 to 5% by weight, preferably 0.5 to 2.0% by weight, and the same is true for rhodium and platinum. If the supported amount is less than 0.05% by weight, the activity is insufficient, which is not preferable, and if it exceeds 5% by weight, the effect of the carrier is lost, which is not preferable.

The catalyst of the present invention is prepared by, for example, preparing a solution of palladium, rhodium or platinum nitrate, chloride, acetate or the like, and then subjecting them to a known method such as an impregnation method, an ion exchange method or a kneading method. It is obtained by carrying it on and then firing. The catalyst thus obtained can be used by being formed into particles of, for example, about 12 to 28 mesh, and can also be used in a honeycomb.

Examples of the hydrocarbon in the present invention include methane, ethane, propane, butane and the like.

[0008]

INDUSTRIAL APPLICABILITY According to the present invention, a trace amount of hydrocarbon of about 5000 ppm or less, preferably about 3000 ppm,
In particular, a gas containing methane, preferably in the presence of water vapor, for example, combustion exhaust gas of fuel, coexists with about 5
When applied to a gas containing a trace amount of 000 ppm or less, preferably about 3000 ppm, especially methane, it is possible to efficiently burn hydrocarbons, especially methane, at a temperature significantly lower than that of conventional catalysts. Thus, a catalyst for combustion of hydrocarbons, especially methane, which is excellent in low-temperature activity and is advantageous for use in burners, combustors, exhaust gas treatment, and the like because of its thermal efficiency, etc.

[0009]

The present invention will be described in more detail with reference to Examples and Comparative Examples.

Example 1 Palladium nitrate (Pd (NO ₃ ) ₂ · 1.5H ₂ O) 1
g was dissolved in pure water in a measuring flask to obtain 100 ml of an aqueous solution. Product name MSZ- manufactured by Tosoh Corporation in a volumetric flask.
690 HOD (SiO ₂ / Al ₂ O ₃ molar ratio = 210)
Mordenite-type zeolite (hereinafter sometimes abbreviated as mordenite) having a particle size of 12 to 28 mesh was put in an amount of 10 g, and 25 ml of a palladium nitrate solution was added.
Furthermore, 75 ml of pure water was added, and the mixture was evaporated in a vacuum by a rotary evaporator for about 2 hours and then at 115 ° C. for 1 hour.
Allowed to dry overnight. Further, it was calcined at 500 ° C. for 3 hours to obtain palladium (1 wt%) / mordenite catalyst (hereinafter sometimes referred to as catalyst 1). In a microreactor (fixed bed flow type reactor) filled with the catalyst 1, the oxygen gas 1
Combustion experiments were carried out by changing the combustion temperature under the condition of SV40000h ^-1 through a mixed gas consisting of 0% by volume, 10% by volume of steam, 3000 ppm of methane and the remaining nitrogen gas (hereinafter sometimes abbreviated as hydrocarbon 1). I did. Table 1 shows the relationship between the combustion temperature and the methane reaction rate. As is clear from the results in Table 1, the conversion rate of methane at 400 ° C. was 83%, which reached almost 100% at 425 ° C.

Example 2 An experiment similar to that of Example 1 was carried out except that a catalyst having a palladium loading of 0.5% by weight (hereinafter sometimes referred to as catalyst 2) was used in the catalyst of Example 1. The results obtained are shown in Table 1.

Example 3 The catalyst of Example 1 had a palladium loading of 2% by weight.
The same experiment as in Example 1 was carried out except that the catalyst (hereinafter sometimes referred to as catalyst 3) was used. The results obtained are shown in Table 1.

Example 4 The catalyst of Example 1 had a palladium loading of 2% by weight.
Palladium nitrate solution was prepared so that the mordenite carrier was added thereto, and the mixture was immersed for 12 hours, washed with water, and then dried, and then palladium (2% by weight) /
Mordenite (hereinafter sometimes referred to as catalyst 4) was obtained. The same experiment as in Example 1 was conducted except that this catalyst 4 was used. The results obtained are shown in Table 1.

Example 5 1 g of RhCl ₃ .3H ₂ O was dissolved in 100 ml of pure water, and rhodium (1 wt%) / mordenite catalyst (hereinafter sometimes referred to as catalyst 5) was dissolved in the same manner as palladium. Obtained. The same experiment as in Example 1 was conducted except that the above catalyst 5 was used. The results obtained are shown in Table 1.

Example 6 Platinum (1% by weight) obtained in the same manner as in Example 1 by dissolving 1 g of H ₂ PtCl ₆ .5H ₂ O in 100 ml of pure water.
/ Mordenite catalyst (hereinafter sometimes referred to as catalyst 5)
The same experiment as in Example 1 was performed except that The results obtained are shown in Table 1.

Example 7 The same experiment as in Example 1 was conducted, except that a mixed gas consisting of 10% by volume of oxygen, 3000 ppm of methane and the remaining nitrogen was used. The results obtained are shown in Table 1.

Comparative Examples 1 to 4 The same experiments as in Example 1 were carried out except that the catalysts shown in Table 1 were used. The results obtained are shown in Table 1.

Comparative Example 5 The same experiment as in Example 7 was carried out except that the catalyst of Comparative Example 2 was used. The results obtained are shown in Table 1.

[0019]

[Table 1] In Table 1, 1) mordenite is a mordenite type zeolite manufactured by Tosoh Corporation, trade name HSZ-620HOD (Si
O ₂ / Al ₂ O ₃ molar ratio = 15) means a carrier, and 2) alumina is a catalyst course 9 volumes. Industrial catalytic reaction II. p206
(1985), edited by The Society of Catalysis, means a γ-alumina carrier obtained by calcining at 700 ° C., which is used for a catalyst supporting a noble metal as a conventionally known low / medium temperature combustion catalyst, and 3) silica is the same. Introduced in the above literature,
It means a silica carrier used for a conventionally known low / middle temperature combustion catalyst, and 4) Silica-alumina is used for a catalyst supporting a noble metal as a conventionally known low / middle temperature combustion catalyst which is also introduced in the above document. Means a silica-alumina carrier which is used.

Comparative Examples 6 to 10 Combustion experiments were carried out on a mixed gas consisting of 10% by volume of oxygen, 2% by volume of methane and the remaining nitrogen using the same catalyst as in Example 1, and the ignition temperature was used as a standard for the low temperature activity of the catalyst. When measured, it was 290 ° C. (Comparative Example 6). When an experiment similar to that of Comparative Example 6 was carried out except that the catalyst of Comparative Example 2 was used, the ignition temperature was 290 ° C. (Comparative Example 7).
When an experiment similar to that of Comparative Example 6 was performed except that the catalyst of Example 6 was used, the ignition temperature was 330 ° C. (Comparative Example 8). When an experiment similar to that of Comparative Example 6 was performed except that the catalyst of Example 5 was used, the ignition temperature was 440 ° C. (Comparative Example 9). When an experiment similar to that of Comparative Example 6 was performed, except that a mixed gas consisting of 10% by volume of oxygen, 1% by volume of propane and the remaining nitrogen was used, the ignition temperature was 290 ° C. (Comparative Example 10).

[Procedure amendment]

[Submission date] June 16, 1993

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[0002]

2. Description of the Related Art Conventionally, for example, "Fuel Association Magazine" Vol. 58, No. 625 (1979), 422-4.
On page 31, for 1% methane-air gas, a palladium-alumina catalyst is preferable as a catalyst for its combustion. For example, in the case of 0.5% Pd-alumina, the methane conversion rate at 350 ° C is 20% and the combustion start temperature is 210 ° C. Et al (Mez
aki et al. ) Report, 4% methane air gas, Malinsky that palladium-alumina catalyst is excellent as a catalyst for its combustion (Malinsky)
And Firth et al.'S report that alumina-supported iridium catalysts or zeolite-supported palladium catalysts have high activity as methane combustion catalysts. In the above conventional technology,
Although it has been reported to use zeolite as a carrier of a hydrocarbon combustion catalyst, there is no specific description about using a mordenite type zeolite carrier,
Further, although the case of using 1 to 4% methane-air gas is described, a hydrocarbon combustion catalyst, for example, a combustion exhaust gas of fuel, has a hydrocarbon content of 300.
It is a trace amount of 0 ppm, and the amount of water vapor is 5-10.
It is needless to say that the case of using a gas in which 5% by volume of oxygen and 5-10% by volume of oxygen coexist is not described, of course, about 5000 ppm or less, preferably 3000 ppm.
It does not specifically describe the case of using a gas containing a very small amount of hydrocarbon, especially methane. on the other hand,
In the case of the above combustion exhaust gas, waste heat is sufficiently recovered, and its exhaust temperature is usually 200 to 400 ° C. For example, a minute amount of hydrocarbons, especially methane, contained in the combustion exhaust gas is used. When burning and removing
Combustion at a low temperature of about 400 ° C. is preferable because the heating energy required therefor can be reduced, and the development of a hydrocarbon combustion catalyst that is highly active at low temperatures is desired. The present invention relates to a gas containing a trace amount of hydrocarbons, particularly about 3000 ppm, particularly methane, such as a gas containing methane, preferably about 5 to 10% by volume of water vapor and oxygen such as combustion exhaust gas of fuel. 5
-10% by volume each coexist, about 5000 ppm or less,
When applied to a hydrocarbon containing a trace amount of about 3000 ppm, especially methane, it has high activity at low temperature and is advantageous in applications such as burner, combustor, and exhaust gas treatment due to its thermal efficiency, especially methane. The purpose of the present invention is to provide a combustion catalyst.

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The catalyst of the present invention is prepared by, for example, preparing a solution of palladium, rhodium or platinum nitrate, chloride, acetate or the like, and then subjecting them to a known method such as an impregnation method, an ion exchange method or a kneading method. It is obtained by carrying it on and then firing. The catalyst thus obtained can be used by being formed into particles of, for example, about 12 to 28 mesh, and can also be used in a honeycomb. When loaded
The above solution should have a pH value in the range of 1.5 to 3.0.
It is preferable to prepare

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Examples of the hydrocarbon in the present invention include methane, ethane, propane, butane and the like. The catalyst of the present invention is less than about 5000 ppm, preferably
A very small amount of hydrocarbons of about 3000 ppm, especially methane
Gas containing gas, preferably, for example, combustion exhaust gas of fuel
Like water vapor, especially 5 to 10% by volume of water vapor and oxygen
5 to 10% by volume coexisting with each other, and about 5000 ppm or less
Below, preferably a trace amount of hydrocarbons of about 3000 ppm,
Especially applicable to gas containing methane
It

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Example 1 Palladium nitrate (Pd (NO ₃ ) ₂ · 1.5H ₂ O) 1
g was dissolved in pure water in a measuring flask to obtain 100 ml of an aqueous solution. In another volumetric flask, trade name MS manufactured by Tosoh Corporation
_{Z-690HOD (SiO 2 / Al} 2 O 3 molar ratio = 21
0) 10 g of mordenite-type zeolite (hereinafter sometimes abbreviated as mordenite) sized to 12 to 28 mesh was put, and 25 ml of the above palladium nitrate solution was added. Furthermore, after adding 75 ml of pure water and evaporating under vacuum for about 2 hours by a rotary evaporator, 11
It was dried overnight at 5 ° C. Further, it was calcined at 500 ° C. for 3 hours to obtain palladium (1 wt%) / mordenite catalyst (hereinafter sometimes referred to as catalyst 1). Above palladium nitrate
The pH value of the solution was 2.2. In a microreactor (fixed bed flow reactor) filled with the above catalyst 1, oxygen gas 10% by volume, water vapor 10% by volume, methane 3000 p
SV40000h through a mixed gas consisting of pm and the remaining nitrogen gas (hereinafter sometimes abbreviated as hydrocarbon 1)
Under the condition of ^-1 , the combustion experiment was conducted by changing the combustion temperature. Table 1 shows the relationship between the combustion temperature and the methane reaction rate. As is clear from the results in Table 1, the conversion rate of methane at 400 ° C. was 83%, which reached almost 100% at 425 ° C.

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Example 2 An experiment similar to that of Example 1 was carried out except that a catalyst having a palladium loading of 0.5% by weight (hereinafter sometimes referred to as catalyst 2) was used in the catalyst of Example 1. The results obtained are shown in Table 1. Of the palladium nitrate solution added to the carrier
The pH value was 2.4.

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Example 3 The catalyst of Example 1 had a palladium loading of 2% by weight.
The same experiment as in Example 1 was carried out except that the catalyst (hereinafter sometimes referred to as catalyst 3) was used. The results obtained are shown in Table 1. P of palladium nitrate solution added to the carrier
The H value was 2.0.

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Example 4 The catalyst of Example 1 had a palladium loading of 2% by weight.
A palladium nitrate solution corresponding to is prepared, and a mordenite carrier is added and immersed for 12 hours for ion exchange.
After, washed with water, then was obtained in the same manner as in Example 1 except that drying of palladium (1 wt%) / mordenite (sometimes referred to as less catalyst 4). The same experiment as in Example 1 was conducted except that this catalyst 4 was used. The results obtained are shown in Table 1. The pH value of the palladium nitrate solution is 2.0
Met.

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Example 5 1 g of RhCl ₃ .3H ₂ O was dissolved in 100 ml of pure water, and rhodium (1 wt%) / mordenite catalyst (hereinafter sometimes referred to as catalyst 5) was dissolved in the same manner as palladium. Obtained. The same experiment as in Example 1 was conducted except that the above catalyst 5 was used. The results obtained are shown in Table 1. Carrier
The pH value of the rhodium chloride solution added to is 2.7
there were.

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Example 6 Platinum (1% by weight) obtained in the same manner as in Example 1 by dissolving 1 g of H ₂ PtCl ₆ .5H ₂ O in 100 ml of pure water.
/ Mordenite catalyst (hereinafter sometimes referred to as catalyst 5)
The same experiment as in Example 1 was performed except that The results obtained are shown in Table 1. The pH value of the platinum chloride solution is 2.
It was 0.

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Example 7 The same experiment as in Example 1 was conducted, except that a mixed gas consisting of 10% by volume of oxygen, 3000 ppm of methane and the remaining nitrogen was used. The results obtained are shown in Table 1. Added to carrier
The pH value of the palladium nitrate solution prepared was 2.2.

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Comparative Examples 1 to 4 The same experiments as in Example 1 were carried out except that the catalysts shown in Table 1 were used. The results obtained are shown in Table 1. Bear
The pH value of palladium nitrate solution added to the body is
It was 2.2.

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Comparative Example 5 The same experiment as in Example 7 was carried out except that the catalyst of Comparative Example 2 was used. The results obtained are shown in Table 1. Added to the carrier
The pH value of the palladium nitrate solution was 2.2.

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[0019]

[Table 1]

Claims (2)

[Claims] 1. A hydrocarbon combustion catalyst comprising a mordenite-type zeolite carrier having a high SiO ₂ / Al ₂ O ₃ molar ratio and a metal selected from palladium, rhodium and platinum. 2. The catalyst according to claim 1, wherein the metal is palladium.