JPH0596176A - Catalyst body - Google Patents

Abstract

PURPOSE:To remove odorous matters in an environment of an instrument or apparatus for room heating, hot water supply, drying, cooking, cold storing, air conditioning or the like for a long period using a catalyst body comprising a zeolite, inorg. binder and inorg. oxide matter with a noble metal deposited on the surface. CONSTITUTION:This catalyst body consists of a zeolite (e.g. copper ion- exchanged A-type zeolite), inorg. binder (e.g. silica) and inorg. oxide matter (e.g. alumina) with a noble metal (e.g. Pt) deposited on the surface. This catalyst body is used normally to adsorb odorous matters and intermittently heated so that the catalyst can maintain the deodorizing ability for a long period. Further, by depositing the noble metal on an inorg. oxide such as alumina, silica, zirconia, and magnesia, the catalytic function of noble metal can be enough used compared with such a case that the noble metal is disposed in pores of zeolite.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a catalyst used for deodorization in heating, hot water supply, drying, cooking, refrigerating, air conditioning equipment and the like.

[0002]

2. Description of the Related Art Conventional deodorizing methods are known, such as deodorizing by adsorbing odorous substances such as activated carbon and zeolite, and deodorizing by sending odor to a heated catalyst to cause oxidative decomposition. Further, recently, a method has been taken in which a device having an ozone generating function is arranged in a room and odorous components are oxidatively decomposed by ozone gas.

[0003]

However, such a conventional deodorizing method has the following problems.

[0004] Conventional activated carbon and zeolites that deodorize by adsorption of odorous substances require replacement when adsorption reaches saturation. Further, in the case of deodorizing with a catalyst, there is a problem that deodorization cannot be performed unless the catalyst is constantly heated. Furthermore, in the odor decomposition method using ozone, a special device must be provided to control the optimum ozone generation concentration for decomposition and deodorization, that there are odor component species that are difficult to decompose by ozone, and the ozone generator The problem is that it has a long life.

The present invention has been made in order to solve the above-mentioned problems of the prior art, and provides a function of completely removing odors and harmful gases with a simple structure and with a long life.

[0006]

The present invention comprises a zeolite, an inorganic binder and an inorganic oxide having a noble metal supported on the surface thereof, and the inorganic oxide contains at least alumina, silica, zirconia and magnesia. Is.

[0007]

[Function] Since the catalyst body contains a zeolite having a large specific surface area, when the ambient air is brought into contact with the catalyst body, the malodorous components such as amine and mercaptan are adsorbed by the zeolite to heat the catalyst body. Deodorization can be performed without Furthermore, when the adsorption capacity of the zeolite reaches saturation, the catalyst body is heated, or the heated air is brought into contact with the catalyst body to activate the precious metal that is the catalyst substance, and the air in contact with the catalyst body The odorous substance is deodorized by oxidative decomposition, and the odorous substance adsorbed by the zeolite is also oxidatively decomposed by the noble metal to regenerate the adsorption ability of the zeolite. As described above, normally, the deodorizing ability can be maintained for a long period of time by adsorbing the odorous substance at room temperature and intermittently heating the catalyst body.

Here, when a precious metal salt is put in a slurry together with zeolite and the precious metal is carried by firing this, the precious metal is also carried in the pores of the zeolite, and when the odor substance is larger than the pores, the odor is increased. Noble metals do not perform well because substances cannot enter the pores. The same problem occurs even if a precious metal salt-free slurry is prepared, calcined, and then loaded with a precious metal salt solution. On the other hand, by supporting a noble metal on the surface of an inorganic oxide such as alumina, silica, zirconia, or magnesia, preparing a slurry in which an inorganic oxide, a zeolite, and an inorganic binder are mixed, and then firing,
Since the noble metal exists only on the surface of the inorganic oxide, the function of the carried noble metal is sufficiently exerted. Alumina is most preferable as the inorganic oxide used in the present invention. By using alumina, it becomes more active in oxidation purification characteristics than other inorganic oxides.

[0009]

EXAMPLES Alumina of the present invention has β-, γ-, δ-, θ
Metastable alumina such as −, η−, ρ−, χ− alumina.

The content of alumina in the catalyst body of the present invention is preferably 20 to 80 wt%. If the content of alumina is less than 20 wt%, the catalytic noble metal is less likely to be highly dispersed, and sufficient catalytic activity cannot be obtained.
If it exceeds%, the odor adsorption capacity of the catalyst decreases.

Various zeolites can be used as the zeolite of the present invention. Among them, copper ion-exchanged A-type zeolite has the best adsorption property for odorous substances.

Further, as the inorganic binder, silica is the most excellent as a binder, and it is possible to form a film which is not easily peeled off from the base material when the catalyst body is carried on the surface of the base material without deteriorating the catalytic properties. it can.

As the noble metal of the present invention, Pt or Pd is used.
Is preferable, and more preferable when both Pt and Pd are used. This is because the oxidative decomposition power of Pt and Pd is higher than that of Rh and Ir, and the higher activity is obtained by using both Pt and Pd. Furthermore, Ru
When used, Ru is volatilized and becomes a harmful substance when used at high temperature.

It is desirable to include cerium oxide in the catalyst body of the present invention. By including cerium oxide in the catalyst body, the catalytic oxidative decomposition activity for hydrocarbon compounds can be improved.

The cerium oxide content of the present invention is preferably 2 to 15 wt% in the catalyst body. When the content of cerium oxide exceeds 15 wt%, the oxidative decomposition characteristics of the catalyst begin to deteriorate, and when it is less than 2 wt%, a sufficient addition effect of cerium oxide cannot be obtained.

It is desirable to include barium oxide in the catalyst body of the present invention. By including barium oxide in the catalyst body, the oxidative decomposition characteristics of the catalyst can be improved. The same effect can be obtained by using barium carbonate instead of barium oxide of the present invention.

The specific surface area of the catalyst body of the present invention is 10 m ² /
It is preferably g or more. This is because, as the specific surface area of the catalyst increases, the far-infrared radiation amount ratio relative to the emitted near-infrared amount increases, but the specific surface area is 10 m ^2.
This is because a sufficient far-infrared radiation ratio can be obtained at / g or more.

When the substrate is coated, the median particle diameter of the particles in the mixed slurry of the present invention is preferably 1 μm or more and 9 μm or less. If it exceeds 9 μm, the coating layer becomes soft, and if it is thinner than 1 μm, cracks are likely to occur in the coating layer.

The catalyst body of the present invention may be formed as a coating on the surface of a base material, molded into pellets, or wrapped in a non-woven fabric using powder.

Specific examples will be shown below. (Example 1) Chloroplatinic acid, alumina, and water were sufficiently mixed using a ball mill, followed by firing at 500 ° C and pulverization to prepare Pt-supported alumina. 160 g of this Pt-supported alumina and 20 wt% converted to silicic acid anhydride
% Silica Acid Colloid Aqueous Solution Containing 10% and Water 200 g
And 160 g of copper ion-exchanged A-type zeolite were thoroughly mixed using a ball mill to prepare slurry A. The average particle size of this slurry was 4.5 μm.
This slurry was coated on a cordierite honeycomb type carrier by a dip method so that the film thickness became 150 μm,
The catalyst A was formed by firing at 500 ° C. The amount of noble metal was 25 mg per 1 g of the coating layer.

This honeycomb type catalyst A is installed behind the flame forming portion of the oil stove, the exhaust gas of the stove passes through the catalyst, and the temperature of the catalyst is 300 to 500 ° C. during steady combustion.
I tried to become. As a result, compared to those without a catalyst,
The odor became weak both at the start of combustion and during steady combustion. this is,
This is because at the start of combustion, the odorous component is adsorbed on the catalyst by the zeolite, and at the steady combustion, the catalyst is warmed and the odorous component is oxidatively decomposed by the noble metal.

Slurry B was prepared by sufficiently mixing chloroplatinic acid, alumina, colloidal silicic acid aqueous solution, water and copper ion-exchanged A-type zeolite with a ball mill. Using this slurry, a catalyst body B was similarly prepared in which a noble metal was also supported on copper ion-exchanged A-type zeolite and silica.

Further, at the time of preparing the slurry A, alumina containing no noble metal is used to form an alumina-zeolite coating layer on the honeycomb type carrier as in the case of the catalyst body A.
It was impregnated with an aqueous solution of chloroplatinic acid by the dipping method and heat-treated to prepare a catalyst body C carrying Pt in the same amount as the catalyst body A.

For these catalyst bodies A, B and C, the diameter is 2c
m Cut out into a column of 3 cm in length, put it into a quartz tube with an inner diameter of 2 cm, and add 100 ppm of isovaleric acid to the quartz tube.
The catalyst was heated at 10 ° C./min while flowing at 00 ml / min, and the temperature dependence of isovaleric acid purification ability was examined. The results are shown in (Table 1).

[0025]

[Table 1]

As is clear from Table 1, the catalyst bodies B and C in which the copper ion-exchanged A-type zeolite and silica also carry the noble metal are lower than those of the catalyst body A in which the noble metal is supported on the alumina surface. It was active. It is considered that this is because the odorant is larger than the zeolite pores and the odorant cannot enter the pores, and thus the precious metal present in the pores (about several angstroms) of the zeolite does not function effectively. On the contrary, when the precious metal is present on the surface of alumina, the function of the supported precious metal can be sufficiently exhibited.

(Example 2) Catalyst body A prepared in Example 1
In, a catalyst body was prepared by replacing alumina in the catalyst body with various inorganic oxides as shown in (Table 2).

Each of these catalyst bodies was cut into a cylindrical shape having a diameter of 2 cm and a length of 3 cm, which was placed in a quartz tube having an inner diameter of 2 cm, and 100 ppm of isovaleric acid of 100 ppm was put into the quartz tube.
The catalyst was heated at 10 ° C./min while flowing at 1 / min, and the temperature dependence of isovaleric acid purification ability was examined. The temperatures at which the conversion rate is 50% are shown in (Table 2).

As shown in (Table 2), the use of alumina, silica, zirconia, and magnesia improved the activity as compared with the case of the catalyst body B of Example 1 in which the noble metal was also supported on the zeolite. Among them, the highest activity was obtained when alumina was used.

From the above results, by loading a noble metal on alumina, silica, zirconia, magnesia,
The activity is improved as compared with the case where the noble metal is present in the pores of the zeolite. Of these, it is most desirable to use alumina.

[0031]

[Table 2]

(Example 3) Catalyst body A prepared in Example 1
In, a catalyst body was prepared by replacing the copper zeolite in the catalyst coating layer with another ion exchange zeolite. These catalyst bodies were tested for their ability to adsorb odorants at room temperature using methyl mercaptan, which is a typical odorant. The test method was a honeycomb type catalyst with a diameter of 2
cm Cut out into a cylinder with a length of 3 cm, and cut it into an inner diameter of 2 cm
Into the quartz tube of No. 3, 50 ppm of methyl mercaptan was passed through the quartz tube at 100 ml / min, and the time required for the methyl mercaptan to break through was determined. The results are shown in (Table 3).

As is clear from (Table 3), since it takes a long time for the copper ion-exchanged A-type zeolite to break through most, copper ion-exchanged zeolite has the best odor substance adsorption ability, and is therefore desirable. Conceivable.

[0034]

[Table 3]

(Example 4) At the time of preparing the slurry A of Example 1, various milling times in a ball mill were changed to prepare various slurries having a central particle diameter of 0.8 µm to 15 µm. Using this slurry, a honeycomb type carrier was coated in the same manner as in Example 1 to form a catalyst body. Next, the film hardness of the coating layer formed here was examined by the pencil hardness test of JIS G-3320. The results are shown in (Table 4).

As is clear from (Table 4), if it exceeds 9 μm, the coating layer becomes soft, and if it is thinner than 1 μm, the coating layer tends to crack.

Therefore, the median particle diameter of the particles in the mixed slurry of the present invention is preferably 1 μm or more and 9 μm or less.

[0038]

[Table 4]

[0039]

As described above, in the present invention, the odor of the atmosphere in which the catalyst is placed is purified by the adsorption action of zeolite, and the catalyst is heated when the adsorption capacity of zeolite reaches saturation. Alternatively, the heated air is brought into contact with the catalytic body to activate the noble metal that is the catalytic substance, deodorize the odorous substances in the air that have come into contact with the catalytic body, and oxidize the odorous substances adsorbed by the zeolite with the noble metal. It can decompose and regenerate the adsorption capacity of zeolites. Further, since the noble metal is supported on the surface of the inorganic oxide such as alumina, silica, zirconia, magnesia, the catalytic function of the noble metal can be sufficiently exhibited as compared with the case where the noble metal is present in the zeolite pores.

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Kyoe Yamade 1006 Kadoma, Kadoma City, Osaka Prefecture Matsushita Electric Industrial Co., Ltd.

Claims (3)

[Claims] 1. A catalyst body comprising a zeolite, an inorganic binder, and an inorganic oxide having a precious metal supported on the surface thereof, the inorganic oxide containing at least alumina, silica, zirconia, and magnesia. 2. The catalyst body according to claim 1, wherein the inorganic oxide is alumina. 3. The catalyst body according to claim 1, wherein the zeolite is a copper ion-exchanged A-type zeolite.