JP2000225344A - Preparation of catalyst for removing hydrocarbon in methane-containing exhaust gas - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a method for preparing a catalyst for removing low concentration hydrocarbons in an exhaust gas containing excess oxygen which demonstrates high removal performance even for an exhaust gas in which a methane content in hydrocarbons is high and indicates stable catalytic activity over a long period even in the presence of sulfur compounds. SOLUTION: Slurry produced by mixing at least one catalyst precursor selected from a zirconium oxide catalyst precursor carrying palladium, a catalyst precursor in which palladium is supported on zirconium oxide treated to increase acidity in advance, and a catalyst precursor in which sulfate radicals and palladium are carried on the surface of zirconium oxide, a binder, and a solvent, a fire-proof honeycomb base material, after being immersed in the slurry, is dried and baked.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for producing a catalyst for removing hydrocarbons in an exhaust gas containing methane and containing an excessive amount of oxygen.

[0002] In the present invention, "exhaust gas containing excess oxygen" or "exhaust gas containing excess oxygen" means that exhaust gas to be treated completely oxidizes methane and other reducing substances contained therein. This means that the exhaust gas contains oxygen in a necessary amount or more.

[0003] The term "catalyst precursor" means a powder of palladium or palladium / platinum supported on various forms of zirconia carriers.

[0004] Further, "honeycomb catalyst" means a catalyst in which the above-mentioned catalyst precursor is fixed on a refractory honeycomb substrate.

[0005]

2. Description of the Related Art It has been known that a catalyst carrying a platinum group metal such as platinum or palladium exhibits high performance in oxidizing and removing hydrocarbons other than methane in exhaust gas containing excess oxygen. . For example, JP-A-51-106691 discloses an exhaust gas purification catalyst in which platinum or palladium is supported on an alumina carrier. However,
When the main component of hydrocarbons is methane, such as the exhaust gas from natural gas, the problem is that even with such a catalyst, sufficient purification effect cannot be achieved because methane has high chemical stability. There is.

Further, since poisoning substances such as sulfur oxides are usually present in the combustion exhaust gas, it is inevitable that the catalytic activity is significantly reduced with time. Since petroleum-based fuels such as kerosene and light oil contain sulfur-containing compounds, it is natural that the combustion exhaust gas contains sulfur oxides. In addition, natural gas-derived fuels that essentially do not contain sulfur compounds, such as city gas supplied in Japan, contain compounds containing sulfur as odorants. The generated sulfur oxides are inevitably contained.

Japanese Patent Application Laid-Open No. 8-332393 discloses an oxidation catalyst for low-concentration hydrocarbons in an oxygen-excess exhaust gas, in which a honeycomb substrate is provided with at least 7 g / l of palladium and 3 to 20 g / l of platinum via an alumina carrier. A supported catalyst is disclosed. However, even in the case of this catalyst, long-term durability is not sufficient in the presence of a sulfur component, and deterioration of the catalyst activity with time cannot be avoided.

As described above, the catalyst according to the prior art has a serious problem that the catalyst activity is greatly reduced in a short time under the condition that the removal rate of hydrocarbons such as methane is low and the sulfur oxide coexists. .

[0009]

Therefore, the present invention exhibits high removal performance even for exhaust gas containing a high methane content in all hydrocarbons, and is stable for a long time even in the presence of sulfur oxides. It is a main object of the present invention to provide a method for producing a catalyst for removing low-concentration hydrocarbons in exhaust gas containing excess oxygen, which exhibits the above-mentioned catalytic activity.

[0010]

Means for Solving the Problems As a result of repeated studies in view of the problems of the prior art, the inventor has found that a slurry is formed by mixing a binder and a solvent with various forms of zirconium oxide carriers supporting palladium. If the refractory honeycomb substrate is immersed in the slurry, dried and calcined, the resulting catalyst exhibits high resistance to poisoning of the catalytic activity by sulfur oxides, It has been found that even under the treatment conditions described above, a high hydrocarbon removal rate is stably maintained over a long period of time. It has also been found that when platinum is used together with palladium, a higher hydrocarbon removal rate is achieved.

The present invention has been completed based on such new findings, and provides the following method for producing a catalyst for removing hydrocarbons from methane-containing exhaust gas. 1. The catalyst precursor was selected from a zirconium oxide catalyst precursor carrying palladium, a catalyst precursor carrying palladium on zirconium oxide that had been previously subjected to a treatment for increasing acidity, and a catalyst precursor having sulfate and palladium coexisting on the zirconium oxide surface. A catalyst for removing hydrocarbons in a methane-containing exhaust gas, wherein a slurry is formed by mixing a binder and a solvent with at least one kind of the slurry, and a refractory honeycomb substrate is immersed in the slurry, dried and fired. Manufacturing method. 2. Item 2. The method for producing a catalyst for removing hydrocarbons in methane-containing exhaust gas according to Item 1, wherein the amount of palladium supported is 5 to 100 g / l based on the volume of the honeycomb catalyst. 3. Zirconium oxide catalyst precursor supporting palladium and platinum, catalyst precursor supporting palladium and platinum on zirconium oxide which has been subjected to a treatment for increasing acidity, and a catalyst in which sulfate, palladium and platinum coexist on the surface of zirconium oxide A methane-containing exhaust gas, comprising mixing a binder and a solvent with at least one selected from precursors to form a slurry, immersing a refractory honeycomb substrate in the slurry, drying and firing. Method for producing catalyst for removing hydrocarbons in the water. 4. Item 4. The hydrocarbon in the methane-containing exhaust gas according to the above item 3, wherein the supported amount of palladium is 5 to 100 g / l and the supported amount of platinum is 5 to 50% based on the weight of the palladium based on the volume of the honeycomb catalyst. Method for producing removal catalyst. 5. The above items 1-4, wherein the binder is a zirconia sol
The method for producing a catalyst for removing hydrocarbons from methane-containing exhaust gas according to any one of the above.

[0012]

BEST MODE FOR CARRYING OUT THE INVENTION As the zirconium oxide carrier used in the present invention, commercially available zirconium oxide itself or zirconium oxide subjected to a treatment for increasing acidity can be used.

The zirconium oxide carrier subjected to the treatment for increasing the acidity is not particularly limited, and examples thereof include known zirconium oxide carrying a sulfate group and zirconium oxide carrying tungsten.
These can be prepared by a known method. For example, zirconium oxide carrying a sulfate group, contacting amorphous zirconium oxide or zirconium hydroxide with sulfuric acid or impregnating with ammonium sulfate, 500-650 ° C
It is obtained by firing in a temperature range of about. Further, zirconium oxide carrying tungsten can be obtained by, for example, wet-kneading amorphous zirconium oxide or zirconium hydroxide with tungstic acid and then baking it in a temperature range of about 650 to 850 ° C.

The production of zirconium oxide having an increased acidity can be confirmed by measuring the acidity by a known method such as a Hammett indicator. The production of zirconium oxide having an increased acidity obtained by the above method can be confirmed also from the fact that the zirconium oxide shows a tetragonal crystal pattern in the X-ray diffraction method.

In order for palladium to be supported on the zirconium oxide carrier or the zirconium oxide carrier treated to increase the acidity, a solution of a palladium nitrate, an ammine complex or the like may be impregnated with a predetermined zirconium oxide carrier. The solvent containing palladium is preferably an aqueous solution, but may be a mixed solvent further added with a water-soluble organic solvent such as acetone or ethanol. Next, the zirconium oxide support impregnated with palladium is dried in air, and then calcined to obtain a catalyst precursor.
The firing conditions are not particularly limited, but usually 450
About 650 ° C, more preferably about 500 to 600 ° C. If the calcination temperature is too low, palladium or palladium-platinum particles grow during the use of the catalyst, so that the catalyst activity is reduced and stability is impaired. On the other hand, when the firing temperature is too high, the specific surface area may decrease with the progress of the grain growth of the supported metal, and the catalytic activity may decrease.

The catalyst precursor in the form of a sulfate group and palladium coexisting on the surface of zirconium oxide can be obtained, for example, as follows. First, a commercially available zirconium oxide is impregnated in an aqueous solution of ammonium sulfate, dried, and dried.
It is fired in a temperature range of about 650 ° C. Next, the obtained fired body is impregnated with a solution containing palladium ions, dried, and fired in a temperature range of about 450 to 650 ° C. Or,
The one in which sulfate and palladium coexist on the surface of zirconium oxide can also be obtained by contacting palladium-supported zirconium oxide with a sulfur oxide-containing exhaust gas to generate sulfate. For example, when sulfur oxide gas such as SO ₂ and SO ₃ is contained in the exhaust gas, the sulfur oxide is oxidized on the zirconium oxide catalyst carrying palladium to form sulfate groups. By the treatment, a catalyst precursor in which palladium and a sulfate group coexist on the surface of zirconium oxide may be obtained.

In order to obtain a catalyst precursor in which palladium and platinum are supported on a zirconium oxide carrier or a zirconium oxide carrier having an increased acidity, platinum ions are added to a solution containing palladium ions, and the above-mentioned palladium loading method is used. The carrier may be impregnated in accordance with the method described above. Drying and baking of the support after the impregnation may be performed in the same manner as in the case of using palladium alone.

Next, a catalyst precursor comprising palladium-supported zirconium oxide prepared by the above-described method, a catalyst precursor wherein palladium is supported on zirconium oxide which has been subjected to a treatment for increasing acidity, and a sulfate group and palladium are converted to zirconium oxide. At least one of the catalyst precursors coexisting on the surface and an appropriate amount of a binder and a solvent are sufficiently mixed to form a slurry.

The binder is not particularly limited, but zirconia sol, silica sol, alumina sol, titania sol or a mixed sol thereof can be used.
Among these binders, zirconia sol is more preferred.

As the solvent, water and at least one of water-soluble organic solvents such as acetone, ethanol and ethylene glycol can be used. Among these,
Water is more preferred. At the time of mixing when producing a slurry, using a ball mill or the like, thoroughly mix each component,
What is necessary is just to form a uniform slurry.

The coating of the slurry on the refractory honeycomb substrate is performed by immersing the honeycomb substrate in the produced slurry,
It is performed by repeating a series of operations of taking out and drying a plurality of times. The required coating amount can be adjusted by the number of repetitions of the series of operations and the slurry concentration. The material of the refractory honeycomb substrate to be used is not particularly limited, but usually cordierite, metal (for example,
Stainless steel) is used.

Next, the honeycomb substrate coated with the slurry is further dried in air and fired to obtain a desired honeycomb catalyst. If the firing temperature is too high, the supported noble metal component grows in grains, while if too low, the supported noble metal component is less likely to be sufficiently activated. Therefore, in order to obtain a stable and high catalytic activity, the calcination is preferably performed at about 450 to 650 ° C, more preferably at about 500 to 600 ° C.

When the amount of supported palladium in the honeycomb catalyst is too small, the catalytic activity is lowered. On the other hand, when the amount is too large, the particle size of palladium becomes large and palladium cannot be used effectively. Therefore, the amount of supported palladium is usually about 5 to 100 g / l, more preferably about 10 to 60 g / l, based on the volume of the honeycomb catalyst.

When palladium and platinum are used together,
If the amount of platinum is too small, the effect of the combined use is not sufficiently exhibited, whereas if the amount of platinum is too large, the function of palladium as an active metal may be impaired. 100 parts by weight, usually about 5 to 50 parts by weight of platinum, more preferably platinum 10
About 50 parts by weight.

In removing hydrocarbons using the catalyst obtained by the method of the present invention, if the amount of the catalyst is too small, a predetermined removal rate cannot be obtained, so that the space velocity per exhaust gas time (GHSV ), It is desirable to use it under the condition of 500000h ^-1 or less. The larger the amount of catalyst, the lower the space velocity per gas hour (GHSV) and the higher the removal rate, which is advantageous, but on the other hand, for example, GHSV is 1000 h
^When used under the condition of ^-1 or less, it is economically disadvantageous and the pressure loss in the catalyst layer increases. Therefore, the amount of the catalyst used may be appropriately selected under the condition that the GHSV is in the range of 500,000 to 1,000 h ^-1 .

When the methane-containing exhaust gas is treated using the catalyst according to the present invention, if the oxygen concentration in the exhaust gas is extremely low, the decomposition reaction rate of methane decreases. It is desirable that the oxygen concentration in the exhaust gas is at least 2% by volume and that oxygen is present in at least the oxidation equivalent of the reducing component such as hydrocarbons in the exhaust gas, more preferably at least 5 times the oxidation equivalent. If the oxygen concentration in the exhaust gas is too low,
Prior to or during the treatment, the exhaust gas may be mixed with a required amount of an oxygen-containing gas (usually air).

The catalyst for removing hydrocarbons in the methane-containing exhaust gas obtained by the method of the present invention has high activity. However, when the use temperature is too low, the activity is not sufficiently exhibited, and it is difficult to obtain a desired hydrocarbon removal rate. On the other hand, if the operating temperature is too high, the durability of the catalyst may decrease. Further, when the hydrocarbon concentration in the exhaust gas is extremely high, a rapid reaction occurs in the catalyst layer, and there is a risk that the durability of the catalyst is adversely affected. In consideration of these points, the catalyst layer temperature is maintained within a temperature range of about 300 to 700 ° C, and the temperature rise in the catalyst layer (difference between the catalyst layer outlet temperature and the inlet temperature) is 150 ° C or less. It is desirable to treat the exhaust gas while adjusting the reaction conditions so as to be as follows.

Although the combustion exhaust gas usually contains sulfur oxides that significantly reduce the catalytic activity, the catalyst of the present invention exhibits high resistance to the decrease in the activity due to the sulfur component. The removal rate is not substantially affected.

Further, the combustion exhaust gas usually contains about 5 to 15% of water vapor. According to the catalyst of the present invention, such an exhaust gas containing water vapor can be treated without any trouble.

[0030]

According to the present invention, the following remarkable effects are achieved. (1) The catalyst for removing hydrocarbons in methane-containing exhaust gas produced by the method of the present invention has a long-term stable oxidation activity against hydrocarbons such as methane even in exhaust gas containing a large amount of water vapor such as combustion exhaust gas. Shown. (2) The catalyst according to the present invention is also excellent in resistance to sulfur oxides. (3) Therefore, according to the present invention, it has become possible to stably purify an exhaust gas containing a large amount of methane for a long period of time, which has been particularly difficult to treat with a conventional catalyst.

[0031]

EXAMPLES Hereinafter, the present invention will be described in more detail with reference to Examples and Comparative Examples, but the present invention is not limited to these Examples. Example 1 20.9 g of a 23.9% palladium nitrate solution was placed in a beaker, and water 5
0 ml was added, and 50 g of commercially available zirconium oxide was further added. The mixture is kept at 0 ° C. for 12 hours, impregnated, evaporated to dryness, dried at 100 ° C. for 16 hours, and further calcined at 550 ° C. for 4 hours to form a catalyst precursor comprising Pd / zirconium oxide powder. Was prepared.

Next, 40 g of Pd / zirconium oxide powder and 40 g of commercially available zirconia sol (zirconia content: 30.7% by weight)
And 80 g of water were charged into a ball mill and mixed for 12 hours to produce a slurry.

[0033] The cordierite honeycomb (200-cell honeycomb, size diameter 12 mm, length 30 mm) is added to the generated slurry.
Was immersed for about 10 seconds, taken out, and the excess slurry was removed by air blow and dried. A series of operations from dipping in the slurry to drying was repeated five times, and coating was performed at a weight ratio of 32% to the honeycomb substrate. Next, the coated honeycomb was further dried at 100 ° C. for 16 hours and fired at 550 ° C. for 4 hours.

The catalyst thus prepared contained 21.6 g of palladium per liter of the honeycomb catalyst (catalyst 1). Example 2 20.9 g of a 23.9% palladium nitrate solution was placed in a beaker, and water 5
0 ml was added, and 50 g of commercially available zirconium oxide was further added. The mixture was kept at 0 ° C. for 12 hours, impregnated, evaporated to dryness, dried at 100 ° C. for 16 hours, and further calcined at 550 ° C. for 4 hours to obtain Pd / zirconium oxide powder (catalyst precursor) Was prepared.

Next, 25 g of Pd / zirconium oxide powder, 25 g of commercially available silica sol (silica content: 20% by weight) and 75 g of water were charged into a ball mill and mixed for 12 hours to form a slurry.

A cordierite honeycomb (200-cell honeycomb, size diameter 12 mm, length 30 mm) is applied to the generated slurry.
Was immersed for about 10 seconds, taken out, and the excess slurry was removed by air blow and dried. A series of operations from dipping in the slurry to drying was repeated five times, and coating was performed at a weight ratio of 27% to the honeycomb substrate. Next, the coated honeycomb was further dried at 100 ° C. for 16 hours and fired at 550 ° C. for 4 hours.

The catalyst thus prepared contained 19.2 g of palladium per liter of the honeycomb catalyst (catalyst 2). Example 3 20.9 g of a 23.9% palladium nitrate solution was placed in a beaker, and water 5
0 ml was added, and 50 g of commercially available zirconium oxide was further added. The mixture was held at 0 ° C. for 12 hours, impregnated, evaporated to dryness, dried at 100 ° C. for 16 hours, and calcined at 550 ° C. for 4 hours to obtain Pd / zirconium oxide powder (catalyst precursor). ) Was prepared.

Next, 25 g of Pd / zirconium oxide powder, 25 g of commercially available titania sol (titania content: 30% by weight) and 75 g of water
Was charged into a ball mill and mixed for 12 hours to produce a slurry.

[0039] Cordierite honeycomb (200 cell honeycomb, size diameter 12mm, length 30mm)
Was immersed for about 10 seconds, taken out, and the excess slurry was removed by air blow and dried. A series of operations from immersion in the slurry to drying was repeated 12 times, and coating was performed at a weight ratio of 24% to the honeycomb substrate. Next, the coated honeycomb was further dried at 100 ° C. for 16 hours and fired at 550 ° C. for 4 hours.

The catalyst thus prepared contained 19.2 g of palladium per liter of the honeycomb catalyst (catalyst 3). Example 4 20.9 g of a 23.9% palladium nitrate solution was placed in a beaker, and water 5
0 ml was added, and 50 g of commercially available zirconium oxide was further added. The mixture was held at 0 ° C. for 12 hours, impregnated, evaporated to dryness, dried at 100 ° C. for 16 hours, and calcined at 550 ° C. for 4 hours to obtain Pd / zirconium oxide powder (catalyst precursor). ) Was prepared.

Next, 20 g of Pd / zirconium oxide powder, 20 g of commercially available alumina sol (alumina content: 20% by weight) and 40 g of water
Was charged into a ball mill and mixed for 12 hours to produce a slurry.

A cordierite honeycomb (200 cell honeycomb, size diameter 12 mm, length 30 mm) is added to the generated slurry.
Was immersed for about 10 seconds, taken out, and the excess slurry was removed by air blow and dried. A series of operations from immersion in the slurry to drying was repeated five times, and coating was performed at a weight ratio of 29% to the honeycomb substrate. Next, the coated honeycomb was further dried at 100 ° C. for 16 hours and fired at 550 ° C. for 4 hours.

The catalyst thus prepared contained 20.4 g of palladium per liter of the honeycomb catalyst (catalyst 4). Example 5 20.9 g of a 23.9% palladium nitrate solution was placed in a beaker, and water 5
0 ml was added, and 50 g of commercially available zirconium oxide was further added. The mixture was held at 0 ° C. for 12 hours, impregnated, evaporated to dryness, dried at 100 ° C. for 16 hours, and calcined at 550 ° C. for 4 hours to obtain Pd / zirconium oxide powder (catalyst precursor). ) Was prepared.

Next, 40 g of Pd / zirconium oxide powder and 40 g of commercially available zirconia sol (zirconia content: 30.7% by weight)
And 80 g of water were charged into a ball mill and mixed for 12 hours to produce a slurry.

[0045] Cordierite honeycomb (200 cell honeycomb, size diameter 12mm, length 30mm)
Was immersed for about 10 seconds, taken out, and the excess slurry was removed by air blow and dried. A series of operations from dipping in the slurry to drying was repeated 12 times, and coating was performed at a weight ratio of 92% to the honeycomb substrate. Next, the coated honeycomb was further dried at 100 ° C. for 16 hours and fired at 550 ° C. for 4 hours.

The catalyst thus prepared contained 43.2 g of palladium per liter of the honeycomb catalyst (catalyst 5). Example 6 After zirconium hydroxide was impregnated with ammonium sulfate, it was baked at 600 ° C. for 5 hours to obtain zirconium oxide with increased acidity.

20.9 g of a 23.9% palladium nitrate solution was placed in a beaker, 50 ml of water was added, and 50 g of zirconium oxide treated to increase the acidity was added. Mixture at 0 ° C
For 12 hours, impregnated, evaporated to dryness, 100
The resultant was dried at a temperature of 16 ° C. for 16 hours and calcined at a temperature of 550 ° C. for 4 hours to prepare a Pd / zirconium oxide powder (catalyst precursor).

Next, 40 g of Pd / zirconium oxide powder and 40 g of a commercially available zirconia sol (zirconia content: 30.7% by weight)
And 80 g of water were charged into a ball mill and mixed for 12 hours to produce a slurry.

The resulting slurry is applied to cordierite honeycomb (200 cell honeycomb, size diameter 12 mm, length 30 mm)
Was immersed for about 10 seconds, taken out, and the excess slurry was removed by air blow and dried. A series of operations from dipping in the slurry to drying was repeated 12 times, and coating was performed at a weight ratio of 92% to the honeycomb substrate. Next, the coated honeycomb was further dried at 100 ° C. for 16 hours and fired at 550 ° C. for 4 hours.

The catalyst thus prepared contained 43.2 g of palladium per liter of the honeycomb catalyst (catalyst 6). Example 7 Commercially available zirconium oxide was impregnated in an aqueous solution of ammonium sulfate, dried, and fired. For 50 g of this fired body, 23.9
A solution obtained by adding 50 ml of water to 20.9 g of a 10% palladium nitrate solution was added. After holding the mixture at 0 ° C. for 12 hours and performing impregnation,
Evaporate to dryness, dry at 100 ° C for 16 hours, and further at 550 ° C for 4 hours.
By calcination for a period of time, a zirconium oxide powder (catalyst precursor) in which sulfate and Pd coexist was prepared.

Next, 40 g of zirconium oxide powder in which sulfate and Pd coexisted, 40 g of a commercially available zirconia sol (30.7% by weight of zirconia) and 80 g of water were charged into a ball mill and mixed for 12 hours to produce a slurry.

The cordierite honeycomb (200 cell honeycomb, size diameter 12 mm, length 30 mm) was added to the slurry thus formed.
Was immersed for about 10 seconds, taken out, and the excess slurry was removed by air blow and dried. A series of operations from immersion in the slurry to drying was repeated 12 times, and coating was performed at a weight ratio of 92% to the honeycomb substrate. Next, the coated honeycomb was further dried at 100 ° C. for 16 hours and fired at 550 ° C. for 4 hours.

The catalyst thus prepared contained 43.2 g of palladium per liter of the honeycomb catalyst (catalyst 7). Example 8 Approximately 1 ml of 1.65 g of cis [Pt (NO ₂ ) ₂ (NH ₃ ) ₂ ] (containing 60.63% Pt)
Heat and dissolve in 23.9% palladium nitrate solution
20.9 g and 40 ml of water were added, and 50 g of commercially available zirconium oxide was further added. The mixture is kept at 0 ° C. for 12 hours, impregnated, evaporated to dryness, dried at 100 ° C. for 16 hours, and further dried for 5 hours.
By firing at 50 ° C for 4 hours, a Pd-Pt / zirconium oxide powder (catalyst precursor) was prepared.

Then, Pd-Pt / zirconium oxide powder 40 g
And a commercially available zirconia sol 40 g (zirconia content 30.7% by weight) and water 80 g were charged into a ball mill and mixed for 12 hours,
A slurry formed.

A cordierite honeycomb (200 cell honeycomb, size diameter 12 mm, length 30 mm) is added to the resulting slurry.
Was immersed for about 10 seconds, taken out, and the excess slurry was removed by air blow and dried. A series of operations from dipping in the slurry to drying was repeated 12 times, and coating was performed at a weight ratio of 92% to the honeycomb substrate. After drying at 100 ° C. for 16 hours, it was baked at 550 ° C. for 4 hours.

The catalyst thus prepared was composed of 43.2 g of palladium and 8.10 g of platinum per liter of the honeycomb catalyst.
It contained 6 g (catalyst 8). Example 9 1000 ppm of methane, 10% of oxygen, and 6% of carbon dioxide in a reactor catalyst layer (temperature maintained at about 450 ° C.) filled with the honeycomb catalysts (catalysts 1 to 4) obtained in Examples 1 to 4, respectively. ,water vapor
A gas consisting of 10%, 0.3 ppm sulfur dioxide, and the balance helium gas was converted to a GHSV (space velocity per gas hour) of 40
The mixture was circulated under the condition of 000h ^-1 to measure the initial conversion of methane. Table 1 shows the results.

[0057]

[Table 1]

As is evident from the results shown in Table 1, the catalysts obtained in Examples of the present invention exhibited high catalytic activity (methane conversion) even in the presence of sulfur dioxide and steam, which significantly inhibit the catalytic activity. Demonstrate. Example 10 2000 ppm of methane, 1000 ppm of carbon monoxide, and 10% of oxygen in a reactor catalyst layer (temperature maintained at about 450 ° C.) filled with the honeycomb catalysts (catalysts 5 to 8) obtained in Examples 5 to 8, respectively. Gas with a composition of 6% carbon dioxide, 10% steam, 0.3 ppm sulfur disulfide and the balance helium gas was passed under the condition of GHSV (gas hourly space velocity) of 80,000 h ^-1 to determine the methane conversion rate over time. Was measured. The results are shown graphically in FIG.

As is clear from the results shown in FIG. 1, the catalysts obtained in the examples of the present invention exhibited stable catalytic activity (methane conversion) over a long period of time even in the presence of sulfur dioxide, which significantly inhibited the catalytic activity. Demonstrate.

[Brief description of the drawings]

FIG. 1 is a graph showing the catalytic activity (methane conversion over time) of the honeycomb catalysts obtained in Examples 5 to 8 of the present invention.

 ──────────────────────────────────────────────────続 き Continuing on the front page (72) Inventor Ken Tabata 4-1-2, Hirano-cho, Chuo-ku, Osaka-shi, Osaka Inside Osaka Gas Co., Ltd. (72) Inventor Hirofumi Otsuka 4-chome, Hirano-cho, Chuo-ku, Osaka-shi, Osaka 1-2-2 Osaka Gas Co., Ltd. (72) Inventor Hirano Takenori 1385-2 F-term (reference) Fukuta (reference) 4D048 AA18 AB01 AC06 BA08X BA31X BA46X BB02 4G069 AA03 AA08 BA05A BA05B BB10A BB10B BC72A BC72B BC75A BC75B CA02 CA07 CA15 DA06 EA19 ED06 FB15 FB16 FC08

Claims (5)

[Claims] 1. A zirconium oxide catalyst precursor carrying palladium, a catalyst precursor carrying palladium on zirconium oxide which has been previously subjected to a treatment for increasing acidity, and a catalyst precursor comprising a sulfate group and palladium coexisting on the surface of zirconium oxide. Mixing a binder and a solvent with at least one selected from a body to form a slurry, immersing a refractory honeycomb base material in the slurry, drying, and firing the methane-containing exhaust gas. A method for producing a hydrocarbon removal catalyst. 2. The method for producing a catalyst for removing hydrocarbons from methane-containing exhaust gas according to claim 1, wherein the carried amount of palladium is 5 to 100 g / l based on the volume of the honeycomb catalyst. 3. A zirconium oxide catalyst precursor carrying palladium and platinum, a catalyst precursor carrying palladium and platinum on zirconium oxide which has been previously subjected to a treatment for increasing acidity, and a sulfate group, palladium and platinum on the zirconium oxide surface. At least one selected from catalyst precursors coexisting in
Mixing the seed with a binder and a solvent to produce a slurry,
A method for producing a catalyst for removing hydrocarbons in methane-containing exhaust gas, comprising immersing a refractory honeycomb substrate in the slurry, drying and firing. 4. The methane-containing catalyst according to claim 3, wherein the supported amount of palladium is 5 to 100 g / l, and the supported amount of platinum is 5 to 50% based on the weight of the palladium, based on the volume of the honeycomb catalyst. A method for producing a catalyst for removing hydrocarbons in exhaust gas. 5. The method for producing a catalyst for removing hydrocarbons in methane-containing exhaust gas according to claim 1, wherein the binder is a zirconia sol.