JPH0810619A - Ozone decomposing catalyst and decomposing method - Google Patents

Abstract

PURPOSE:To obtain a catalyst reduced in the lowering of catalytic activity even if used for a long time at the normal temp. and excellent in ozone decomposing capacity and durability by supporting at least amorphous manganese oxide and palladium oxide on silica/boria/alumina multiple oxides. CONSTITUTION:An ozone decomposing catalyst is constituted by supporting at least amorphous manganese oxide and palladium oxide on silica/boria/alumina multiple oxides. Oxide of at least one kind of an element selected from a group consisting of Ag, Ir, La and the others may be added to the catalyst. Further, the catalyst is supported with a carrier having a monolithic structure. Gas containing ozone is brought into contact with the catalyst to decompose ozone in the gas. At this time, a sulfur compd. and/or moisture is allowed to coexist in the gas containing ozone. By this constitution, a catalyst reduced in the lowering of catalytic activity even if used for a long time at the normal temp. and excellent in ozone decomposing capacity and durability is obtained.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an ozone decomposition catalyst for decomposing high-concentration ozone present in a gas phase to render it harmless, and an ozone decomposition method using the catalyst.

[0002]

2. Description of the Related Art Ozone is known to be harmful to the human body when it is present in an atmosphere of 0.06 PPM or more. Electric discharge machining is applied to the surface treatment of paper and film, but at that time, several tens of PP
Ozone with a high concentration of M is produced. Further, when ozone is used to sterilize and deodorize organic substances in water, unused ozone is discharged. It is dangerous if it is released into the atmosphere as it is, so it is necessary to decompose it to a minute amount.

Conventionally, as such ozone treatment methods, (1) chemical cleaning method, (2) thermal decomposition method, (3) activated carbon method, and (4) ozone decomposition catalyst method are known. There is. As a method using an ozone decomposition catalyst, for example, JP-A-62-97643 discloses:
As a catalyst for catalytically decomposing and removing ozone in an ozone-containing gas, a binary oxide consisting of Ti and Si, a binary oxide consisting of Ti and Zr and / or a ternary consisting of Ti, Si and Zr A catalyst containing a system oxide as a carrier component is disclosed. Further, Japanese Patent Laid-Open No. 1-56123 discloses a Mn-containing catalyst which has a long treatment life at room temperature or lower. As an example of treating high-concentration ozone, Japanese Patent Application Laid-Open No. 3-15
Japanese Patent No. 1046 discloses a catalyst in which Pd and / or Ag is supported on a manganese dioxide granular molded body.

[0004]

However, in these conventional techniques, the above-mentioned method (1) of chemical cleaning requires an expensive reducing agent. There is also the problem of wastewater treatment. (2) In the method by thermal decomposition, it is necessary to heat the processing gas to 300 ° C. or higher, which increases the processing cost. (3) In the method using activated carbon, the reaction between ozone and activated carbon occurs and the activated carbon is consumed. When the ozone concentration is high, there is a danger of ignition and combustion of activated carbon due to reaction heat. (4) In the method using an ozone decomposition catalyst, the catalyst described in JP-A-62-97643 mentioned above is expensive T
There is a drawback that a large amount of i or Zr is used and the manufacturing method is complicated. When the Mn-containing catalyst described in JP-A-1-56123 is used for ozone decomposition treatment, it is necessary to dehumidify the ozone-containing gas. The catalyst disclosed in JP-A-3-151046 has a short catalyst life and easily poisons a gas in which a sulfur compound coexists, such as a residual gas of ozone used for wastewater treatment. There is a drawback that.

The present invention has been made to solve the above-mentioned problems of the prior art. The object of the present invention is to reduce the catalytic performance even when used for a long time at room temperature, and to reduce the gas flow containing a sulfur compound. Also, it is to provide a catalyst which is excellent in ozone decomposing ability and durability and decomposes a high concentration of ozone existing in a gas phase, and an ozone decomposing method using the same.

[0006]

Means for Solving the Problems As a result of intensive studies conducted by the present inventors, the following silica-boria-alumina composite oxide for ozone decomposition is formed by supporting at least amorphous manganese oxide and palladium oxide. It has been found that a catalyst solves the above problems and achieves the above objects. That is, at least amorphous manganese oxide and palladium oxide are supported on a silica-boria-alumina composite oxide, and more preferably Ag, Ir, La, C.
It was found that a catalyst containing an oxide of at least one element selected from the group consisting of e, Fe, Ni, Y and Sm has excellent ozone decomposing ability and durability, and completed the present invention. Came to do.

In the amorphous manganese oxide of the present invention, it is not necessary that the entire manganese oxide is in an amorphous form, and it is sufficient if there is an amorphous part, but preferably at least half, more preferably at least 80%. It is desirable that 90% or more is amorphous. Further, the catalyst of the present invention is preferably supported on a support having an integral structure such as a honeycomb shape or a hole shape such as alumina, titania or cordierite.

The ozonolysis catalyst of the present invention can be produced by various methods by supporting the required oxides in any order. For example, when the catalyst is carried on a support having an integral structure. The catalyst of the present invention can be produced by the following method.

A support having a monolithic structure is coated with a silica-boria-alumina composite oxide, which is then immersed in a solution of manganese acetate, dried, and fired to support amorphous manganese oxide. Then, it can be manufactured by immersing it in a solution containing a palladium salt, drying it, and firing it to support palladium oxide. When an oxide of another element is added, Ag, Ir, La, Ce, Fe, Ni, Y is added to the solution containing the palladium salt.
And Sm, it can be produced by using a solution obtained by mixing a solution of a salt of at least one element selected from the group consisting of

It is also possible to produce by a method of preparing a slurry comprising a solution of silica-boria-alumina composite oxide, manganese acetate and palladium salt in advance.
That is, a slurry containing silica-boria-alumina composite oxide, a solution of manganese acetate, a solution containing a palladium salt and water is prepared, and the slurry is coated on a support having an integral structure, dried, and fired. It can be produced by supporting a silica-boria-alumina composite oxide, amorphous manganese oxide and palladium oxide. When an oxide of another element is added, a solution of a salt of at least one element selected from the group consisting of Ag, Ir, La, Ce, Fe, Ni, Y and Sm is added to the slurry. It can be manufactured by containing it.

It is also possible that the slurry is first fired and then supported on the structure. That is, silica, boria,
A step of dropping a solution containing manganese acetate and a palladium salt into an alumina composite oxide, drying and calcining, a step of preparing a slurry containing the calcined product and water, and a support having an integrated structure of the slurry. By the steps of coating, drying, and baking the
A catalyst supporting boria-alumina composite oxide, amorphous manganese oxide and palladium oxide can also be produced. In the case of containing an oxide of another element, a solution of manganese acetate, a solution containing palladium, Ag, I
A step of sequentially dropping a solution of a salt of at least one element selected from the group consisting of r, La, Ce, Fe, Ni, Y and Sm, drying and firing, and a slurry containing the fired product and water. It can be manufactured by preparing and coating the slurry on a support having an integral structure, drying and firing.

The present invention also provides a method of decomposing ozone present in the gas phase using a catalyst. That is, the present invention relates to the above catalyst comprising silica-boria-alumina composite oxide carrying at least amorphous manganese oxide and palladium oxide, and preferably to a catalyst comprising a support having an integral structure carrying these. , Concentration of 1 PPM or more, preferably 10 PPM or more, more preferably 100
It also relates to a method of contacting a gas containing ozone of PPM or higher to decompose ozone in the gas. Further, the present invention provides a silica-boria-alumina composite oxide containing at least amorphous manganese oxide, palladium oxide, and Ag, Ir, La, Ce, Fe, Ni, Y and Sm.
The catalyst containing at least one oxide of an element selected from the group consisting of the above, preferably a catalyst having these supported on a support having an integral structure, has a concentration of 1 PPM.
Or more, preferably 10 PPM or more, more preferably 10
The present invention relates to a method of contacting a gas containing 0 PPM or more ozone to decompose ozone in the gas.

Further, in the present invention, a sulfur compound such as sulfur oxide, hydrogen sulfide, and / or water is present in the catalyst in a concentration of 1 PPM or more, preferably 10 PPM.
As described above, more preferably, it relates to a method of contacting a gas containing ozone of 100 PPM or more to decompose the ozone in the gas.

The present invention will be described in detail below. Having an integral structure used in the method for producing the catalyst of the present invention
Examples of the support and the support having the raw material integral structure of the catalyst component include alumina, titania, mullite (silica / alumina), cordierite, zirconia, silicon carbide, metal, and carbon graphite. As the shape of the support, a honeycomb, a home (three-dimensional perforated) shape, a perforated plate, a cloth shape, a fibrous shape, or an expanded metal is preferably used, but a honeycomb is preferable. The preferred shape of the honeycomb is such that the number of holes is 30 to 600 per square inch, the geometric surface area is 2 to 30 square cm per 1 ml of honeycomb volume, and the open area ratio is 60% or more.

The silica-boria-alumina composite oxide used in the production method of the present invention is not simply a mixture of silica, boria and alumina, but is preferably a composite oxide thereof. Either method may be used as the manufacturing method,
For example, alumina-silica obtained by adding an aqueous solution of sodium silicate to an alumina hydrate slurry formed by hydrolysis of an aqueous solution of aluminum sulfate and an aqueous solution of sodium aluminate, and filtering and washing an alumina-silica hydrate slurry. An aqueous orthoboric acid solution was added to the hydrate cake so that B ₂ O ₃ had a predetermined amount and mixed well, and then the obtained alumina-silica-boron mixed hydrate was spray-dried to give 600 After firing at ˜800 ° C., the average particle size is 2 μm to 20 μm, preferably 5 μm to 15 μm
It is a composite oxide obtained by pulverizing to a certain degree.
This may be used as it is, but the alumina-silica-boron mixed hydrate is heated and tempered in a kneader with a heating jacket, and after extrusion molding with a molding machine having a die of a desired shape, You may use it after drying at 80-120 degreeC and baking at 600-1100 degreeC. More preferably, it is further baked in the air at 600 to 1200 ° C. for 1 to 10 hours. The silica boria
The composition of the alumina composite oxide is not particularly limited, but silica is 2 to 25% by weight, preferably 4 to 19% by weight, more preferably 7 to 15% by weight, and boria is 2 to 2.
It is preferably 20% by weight, preferably 3 to 10% by weight, more preferably 3 to 8% by weight, with the balance being alumina.

Further, various salts of manganese can be used as a raw material for producing the amorphous manganese oxide used in the catalyst of the present invention, but organic acid salts are preferable. In order to achieve the object of the present invention, it is essential that the manganese oxide contained in the catalyst of the present invention is amorphous, and in order to obtain amorphous manganese oxide in a wide calcination temperature range, organic acid of manganese is used. It is preferable to use a salt, preferably a lower fatty acid salt of manganese, more preferably manganese acetate as a starting material.

Further, the solution containing a palladium salt used for producing the catalyst of the present invention includes, for example, palladium nitrate, palladium acetate, palladium chloride, palladium sulfate, alkali chloropalladate, ammonium chloropalladate, and ammonium ammine palladium. Examples thereof include dissolving a palladium salt such as a salt or a complex salt in a solvent such as water.
Further, Ag, Ir, L used for producing the catalyst of the present invention
Examples of the solution of a salt of at least one element selected from the group consisting of a, Ce, Fe, Ni, Y and Sm include chloride, acetate, nitrate and carbonate of these elements.
Examples thereof include a salt such as an oxalate salt or a complex salt dissolved in a solvent such as water.

Manufacturing Method As a method of coating a support having an integral structure with a silica-boria-alumina composite oxide, first, an aqueous slurry of the composite oxide is prepared. At this time, alumina sol, silica sol, titania sol as a binder for the slurry,
Y-type zeolite having a silica to alumina ratio of 10 or more may be added. Further, a water-soluble polymer organic compound such as polyethylene glycol may be added. A support having an integral structure is dipped in the slurry, pulled up, and then the excess slurry is removed by air blow.
After that, it is dried at 100 to 110 ° C., and 200 to 60 in the atmosphere.
Baking at 0 ° C. for 1 hour or longer, preferably 3 hours or longer. Next, the support coated with the silica-boria-alumina composite oxide is immersed in a solution of manganese acetate, dried, and then calcined in the air at 200 to 600 ° C. for 1 hour or longer, preferably 3 hours or longer. The manganese oxide supported by this treatment becomes amorphous. The supported amount of manganese oxide is preferably 1 to 100 g, preferably 5 to 100 g, and more preferably 5 to 10 g in terms of metal Mn per liter of the finished catalyst.

Then, the support on which the silica-boria-alumina composite oxide and the amorphous manganese oxide are supported is dipped in the solution of the above-mentioned palladium salt, dried, and then dried in the atmosphere at 200 to 600 ° C. for 1 hour or more, It is preferably baked for 3 hours or more. Palladium supported by this treatment becomes palladium oxide. The loading amount of palladium oxide is 1 to 100 in terms of metallic palladium per liter of the finished catalyst.
g, preferably 2 to 40 g, more preferably 5 to 10 g
Is preferred. In addition, Ag, Ir, La, Ce, Fe, N
In order to further support an oxide of at least one element selected from the group consisting of i, Y and Sm, a mixed solution of the above-mentioned raw material solution and palladium salt solution is used, and the above-mentioned palladium oxide is used. It suffices to carry out the same treatment as in the case of supporting. The amount of each oxide supported is 0.5 to 50 g, preferably 0.5 to 10 g, and more preferably 3 to 10 g in terms of element of each oxide per 1 liter of the finished catalyst.

In another embodiment of the method for producing the catalyst of the present invention, a slurry containing silica-boria-alumina composite oxide, a solution of manganese acetate, a solution containing palladium and water is prepared and integrated with the slurry. The support having the structure is immersed, dried at 100 to 110 ° C. for at least 5 hours, and then baked in the air at 300 to 600 ° C. for 1 hour or more, preferably 3 hours or more. The amount supported on the support is 10 to 300 g, preferably 30 to 200, per liter of the finished catalyst.
g is preferred. In addition, Ag, Ir, La, Ce, Fe,
At least one selected from the group consisting of Ni, Y and Sm
In order to further support the oxide of the seed element, the same treatment may be performed after adding the solutions of these raw materials described above to the slurry. The amount supported on the support is preferably 10 to 300 g, and more preferably 30 to 200 g, per liter of the finished catalyst.

In a further embodiment of the method for producing the catalyst of the present invention, a solution of manganese acetate and a solution containing a palladium salt in a silica-boria-alumina composite oxide are prepared.
Simultaneously or sequentially, after dropping and absorbing the liquid, 100 to 110
Dry at ℃ for at least 5 hours, 300-600 ℃ in air
At 1 hour or longer, preferably 3 hours or longer. In the case of sequential dropping, the order of dropping does not matter. Then, a slurry containing the fired product and water is prepared, a support having an integral structure is immersed in the slurry, dried at 100 to 110 ° C. for at least 5 hours, and then in air at 300 to 600 ° C. for 1 hour or more. ,
It is preferably baked for 3 hours or more. The amount supported on the support is 10 to 300 g, preferably 3 per liter of the finished catalyst.
0 to 200 g is preferable. Also, Ag, Ir, La, C
To further carry an oxide of at least one element selected from the group consisting of e, Fe, Ni, Y and Sm,
A solution of these raw materials described above, a solution of manganese acetate and a solution containing palladium are simultaneously or sequentially added dropwise to the silica-boria-alumina composite oxide to absorb the liquid,
Similar processing may be performed. In the case of sequential dropping, the order of dropping does not matter. The amount supported on the support is preferably 10 to 300 g, and more preferably 30 to 200 g, per liter of the finished catalyst.

Ozone Decomposing Method In the ozone decomposing method of the present invention, it is preferable to use a support having an integral structure so that the direction of the apparatus to be installed is not limited. A gas containing ozone at a concentration of 1 PPM or more, preferably 10 PPM or more, more preferably 100 PPM or more is brought into contact with the catalyst of the present invention to decompose ozone in the gas. The gas hourly space velocity is preferably 500 to 100,000 / hr and is appropriately selected according to the desired ozone concentration at the catalyst outlet. By using the catalyst of the present invention, it is possible to maintain a high ozonolysis activity even under harsh conditions containing saturated steam and / or sulfur compounds.

The life of the catalyst when decomposing ozone is influenced by the concentration of ozone existing in the gas phase. When the ozone concentration is high, oxygen, which is a decomposition product of ozone, is difficult to be desorbed from the catalyst surface, so that ozone is less likely to be adsorbed on the catalyst surface and the decomposition activity of ozone is lowered. is there. Therefore, the catalyst of manganese alone or the structure of manganese oxide is Mn ₂ O ₃ or MnO ₂
In the case of a catalyst that is, even if its ozone decomposing activity is strong at the beginning, if it is used for a long time, the desorption of oxygen, which is an ozone decomposition product, from the catalyst surface proceeds. It becomes difficult to do so, and the catalyst life becomes short.
Surprisingly, it was found that when manganese oxide is amorphous when observed by powder X-ray diffractometry, desorption of oxygen, which is an ozone decomposition product, easily progresses. Further, it was found that the coexistence of palladium oxide accelerates the desorption thereof, and makes it a catalyst excellent in both ozone decomposing ability (decomposition activity) and durability. Therefore, the catalyst of the present invention is not only excellent in catalytic activity, but also can maintain stable catalytic activity for a long time as compared with conventional catalysts. Furthermore, Ag, Ir, La, Ce, F
The addition of an oxide of at least one element selected from the group consisting of e, Ni, Y and Sm further promotes this action. Further, ordinary ozone-containing gas contains impurities such as water vapor, sulfur compounds, and NO _x , and the catalyst is affected by these and the catalytic performance is lowered. Compared with the conventional titania-based catalyst, the catalyst of the present invention is weakly affected by the above-mentioned adsorption of water vapor and impurities. In particular, the silica-boria-alumina composite oxide has a weak adsorption property for the water vapor and impurities, and is not easily affected by these.

[0024]

【Example】

Example 1 A powder of 10% by weight silica, 5% by weight boria, and silica-boria-alumina composite oxide (average particle size 15 μm) consisting of alumina as the balance (average particle size 25 μm, BET) Specific surface area 280 m ² / g) 26
0 g, 20 ml of acetic acid, and 430 ml of pure water were mixed in a ball mill for 12 hours to obtain an average particle size of 5 μm and a dry solid content of 34% by weight.
A slurry of was obtained. A cordierite honeycomb (400 cells / in ² , 10 cm × 10 cm × height 5 cm, capacity 500 ml) was dipped in this slurry and taken out,
The excess slurry was removed with an air knife. further,
After drying at 100 to 110 ° C. for 5 hours, firing was performed at 550 ° C. for 2 hours to coat the honeycomb with the silica / boria / alumina composite oxide.

Next, a manganese acetate aqueous solution (Mn of 7
The silica-boria-alumina composite oxide-coated honeycomb was dipped in (wt%) for 10 seconds, taken out, and then excess slurry was removed with an air knife. Furthermore, 100-11
After drying at 0 ° C. for 5 hours, it was baked at 500 ° C. for 3 hours. The surface of this catalyst was scraped off, and the structure of manganese oxide was examined by powder X-ray diffractometry to find that it was amorphous. Next, the silica-boria-alumina composite oxide-coated honeycomb supporting manganese oxide was immersed in an aqueous palladium nitrate solution (7% by weight as Pd) for 10 seconds, taken out, and then an excess slurry was removed by an air knife. Furthermore, 100-
After drying at 110 ° C. for 5 hours, it was baked at 500 ° C. for 3 hours to obtain the target catalyst-coated honeycomb (1). When the surface of this catalyst was scraped off and the structure of palladium was examined by a powder X-ray diffraction method, it was found to be palladium oxide (PdO). Mn and Pd
Was 6 g per liter of the finished catalyst.

Example 2 In Example 1, except that a mixed solution of an aqueous palladium nitrate solution (7% by weight as Pd) and an aqueous silver nitrate solution (7% by weight as Ag) was used in place of the aqueous solution of palladium nitrate.
The target catalyst-coated honeycomb (2) was obtained in the same manner as in Example 1. The supported amount is 6 g of Mn, P per liter of the finished catalyst.
It was d6g and Ag5g.

Examples 3 to 9 In Example 2, instead of the aqueous silver nitrate solution, an aqueous iridium chloride solution (7 wt% as Ir), an aqueous lanthanum nitrate solution (7 wt% as La), and an aqueous cerium nitrate solution (7 wt% as Ce) were used. %), Iron nitrate aqueous solution (7% by weight as Fe), nickel nitrate aqueous solution (7% by weight as Ni), yttrium nitrate aqueous solution (7% by weight as Y),
Target catalyst-coated honeycombs (3) to (9) were obtained in the same manner as in Example 2 except that an aqueous samarium nitrate solution (7% by weight as Sm) was used. The loading amount of each catalyst-coated honeycomb was 6 g of Mn and P of P for each liter of the finished catalyst.
It was d6g and the 3rd component 5g.

Example 10 260 g of the same silica-boria-alumina composite oxide as used in Example 1, 20 ml of acetic acid, 430 ml of pure water,
115 g of manganese acetate tetrahydrate and an aqueous palladium nitrate solution were mixed in a ball mill for 12 hours so that Pd was 4% by weight based on the weight of the slurry, and the average particle size was 5 μm.
A slurry with a dry solids content of 34% by weight was obtained. The same honeycomb as that used in Example 1 was immersed in this slurry, taken out, and then the excess slurry was removed with an air knife. Furthermore, after drying at 100 to 110 ° C. for 5 hours, 550
The target catalyst-coated honeycomb (10) was obtained by firing at 2 ° C. for 2 hours. The surface of this catalyst was scraped off, and the structure of manganese oxide and palladium was examined by a powder X-ray diffraction method. As a result, manganese oxide was amorphous and palladium was palladium oxide (PdO). The amount of Mn and Pd supported was 6 g per liter of the finished catalyst.

Example 11 To 260 g of the same silica-boria-alumina composite oxide used in Example 1, an aqueous manganese acetate solution (8% by weight as Mn) was added dropwise, and then an aqueous palladium nitrate solution (8% by weight as Pd). %) After being dripped to absorb the liquid, 10
After drying at 0 to 110 ° C. for 5 hours, it was baked at 550 ° C. for 2 hours. Next, the baked product, 20 ml of acetic acid, and 430 m of pure water
1 was mixed in a ball mill for 12 hours to obtain a slurry having an average particle size of 5 μm and a dry solid content of 34% by weight. The same honeycomb as that used in Example 1 was immersed in this slurry, taken out, and then the excess slurry was removed with an air knife.
Furthermore, after drying at 100 to 110 ° C. for 5 hours and firing at 550 ° C. for 2 hours, the target catalyst-coated honeycomb (11) was obtained. The surface of this catalyst was scraped off, and the structure of manganese oxide and palladium was examined by a powder X-ray diffraction method. As a result, manganese oxide was amorphous and palladium was palladium oxide (PdO). The supported amounts of Mn and Pd were both 6 g per liter of the finished catalyst.

Example 12 The same procedure as in Example 11 was repeated except that the aqueous solution of palladium nitrate was added dropwise and then the aqueous solution of silver nitrate (8% by weight as Ag) was added dropwise to absorb the solution. A honeycomb (12) was obtained. The surface of this catalyst was scraped off, and the structure of manganese oxide and palladium was examined by a powder X-ray diffraction method. As a result, manganese oxide was amorphous and palladium was palladium oxide (PdO).
The supported amounts of Mn, Pd and Ag were each 6 g per liter of the finished catalyst.

Comparative Example 1 A commercially available 0.1% by weight palladium manganese dioxide granular molding was prepared.

[Performance Evaluation Example 1] The catalyst-coated honeycombs (1) to (12) obtained in Examples 1 to 12 and the catalyst of Comparative Example 1 were subjected to an ozone decomposition performance evaluation test under the following conditions. An atmospheric fixed bed flow reactor was used. The catalyst-coated honeycombs (1) to (12) of the examples were cut into a size of 2 cm × 2 cm × height of 5 cm, and the catalyst of the comparative example was used as it was because it was a granular body. The inside of the reactor was set to 25 ° C., and air containing saturated steam at 25 ° C. and ozone having a concentration of 700 ppm was passed through the reaction tube at a space velocity of 10,000 / hr.
Silent discharge air-cooled ozone generator for OZ manufactured by EBARA CORPORATION
SD1000 was used. For the analysis of ozone, ultraviolet absorption method EG-2001B and EG-20 manufactured by EBARA CORPORATION
The ozone concentration at the inlet and outlet of the reaction tube was continuously measured using 01R, and the decomposition rate was calculated from the concentration 20 hours after the gas flow. The results are shown in Table 1.

[0033]

[Table 1]

[Performance Evaluation Example 2] In Performance Evaluation Example 1,
A catalyst-coated honeycomb (1) was manufactured under the same conditions as in Performance Evaluation Example 1 except that hydrogen sulfide having a concentration of 20 PPM was added to the inflow gas.
Performance of the catalysts of (2) and Comparative Example 1 was evaluated.
Table 2 shows the results.

[0035]

[Table 2]

From Tables 1 and 2, the catalysts obtained by the production method of the present invention do not deteriorate in ozone decomposing activity even after long-term use, and have excellent performance even when hydrogen sulfide coexists in the gas. It is clear to maintain.

[0037]

The catalyst obtained by the production method of the present invention decomposes ozone present at a high concentration in the gas phase to render it harmless, and its activity does not decrease even when used at room temperature for a long time. Even when a sulfur compound such as hydrogen sulfide coexists in the gas phase, it has excellent ozone decomposing ability and durability.

Continuation of the front page (51) Int.Cl. ⁶ Identification number Office reference number FI technical display location B01J 23/889 B01J 23/84 311 A

Claims (5)

[Claims] 1. A silica-boria-alumina composite oxide,
A catalyst for ozone decomposition, which carries at least amorphous manganese oxide and palladium oxide. 2. Ag, Ir, La, Ce, Fe, N
The catalyst according to claim 1, which contains an oxide of at least one element selected from the group consisting of i, Y, and Sm. 3. The catalyst according to claim 1, which is carried on a support having an integral structure. 4. A method of decomposing ozone in the gas by bringing a gas containing ozone into contact with the catalyst according to claim 1, 2, or 3. 5. The method according to claim 4, wherein the sulfur compound and / or the water coexist in the gas containing ozone.