JPH09306644A - Heating element - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a honeycomb heating element removing harmful, uncomfortable factors and capable of quickly, efficiently removing them. SOLUTION: A heating element comprises at least almost a quadrangular pillar- or plate-shaped SiC honeycomb ceramic resistor 1, a conductive electrode 2 made of at least one selected from aluminum, nickel, copper, brass, and silver, formed on a pair of facing outer wall surfaces of the honeycomb ceramic resistor 1, and a covered catalyst layer 3 formed by covering the surface of the honeycomb ceramic resistor 1, and a calorie output from a heater is varied without use of a cooling means, the removal of harmful, uncomfortable factors is enhanced, and deodorization is quickly, efficiently performed.

Description

Detailed Description of the Invention

[0001]

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

[0002]

2. Description of the Related Art As a heating element having a catalyst coating layer,
A heating element having a catalyst coating layer formed on a quartz tube heater as shown in JP-A-4-281177 and a heating element having a catalyst coating layer formed on a metal honeycomb resistor are known.

[0003]

In the structure in which the catalyst coating layer is formed on the quartz tube heater, since the contact area with the air is small, some of harmful and unpleasant components contained in the air do not come into contact with the catalyst coating layer. It took a relatively long time to achieve the desired reduction of harmful and unpleasant ingredients. Further, since the built-in electric resistor is made of metal, there is a risk of disconnection due to its corrosion. Further, the metal honeycomb-shaped heating element has a problem in durability due to insufficient adhesion of the catalyst coating layer.

The present invention has been made to solve the above problems, and an object of the present invention is to provide a honeycomb heating element which has a high ability to remove harmful and unpleasant components and which can be efficiently removed in a short time.

[0005]

In order to achieve the above-mentioned object, the present invention provides at least a substantially rectangular prismatic or square plate-shaped and honeycomb-shaped ceramic resistor, and a pair of opposing outer peripheral surfaces of the honeycomb body. The contact coating medium layer is formed of a conductive electrode made of at least one selected from aluminum, nickel, copper, brass, and silver, and formed on the surface of the honeycomb-shaped ceramic resistor.

The ceramic resistor of the present invention is made of SiC or PTC.
Ceramic can be used. Of these, PTC ceramics are controlled by the Curie temperature that is unique to the material, so if a heater cooling means such as air blowing is not used, almost no current flows through the heater, and the amount of heat that can be output from the heater is extremely small. A honeycomb resistor made of SiC having NTC characteristics is desirable because the amount of heat output from the heating element can be changed by changing the applied power regardless of the presence of cooling means.

Aluminum is used as the electrode material of the present invention.
Nickel, copper, brass, silver-Pt, silver-Pd, and Pt can be used, and a plurality of electrode materials among them may be used together depending on the purpose. Moreover, various methods can be used as the electrode forming method. For example, the electrode material paste may be applied and then baked, or may be directly applied by metal sputtering, vapor deposition, or thermal spraying. Of these, it is preferable to form the electrode by thermal spraying because the contact resistance between the electrode and the ceramic resistor can be minimized.

Further, in the present invention, it is desirable that the conductive electrode is formed so as to protrude on both side surfaces of the wall surface on which the electrode is formed. This is because it is possible to prevent a temperature decrease on the side surface of the honeycomb heating element and realize a uniform heat generation temperature distribution. It is desirable that the conductive electrode portion formed on both side surfaces of the electrode forming wall surface is 1 mm or more and 5 mm or less from the end surface. This is because a very uniform temperature distribution of the honeycomb heating element can be obtained in the range of the protruding electrode.

By forming the catalyst coating layer on the surface of the heating element of the present invention, harmful gas and unpleasant gas existing in the environment where the heating element is used can be removed. In particular, it is desirable to use a catalyst material having a function of adsorbing an odor when not heated and oxidizing and decomposing when heated so that the gas component can be removed even when the heating element is not heated. The catalyst coating layer formed on the surface of the ceramic resistor contains at least activated alumina, zeolite and platinum group metal, and it is desirable to use them by binding them with an inorganic binder. By using activated alumina, zeolite and platinum group metal at the same time, it is possible to obtain a synergistic effect of improving the adsorption characteristics for acidic odor components as compared with the case of using activated alumina or zeolite alone.

Where a metal resistor is used, metal corrosion proceeds due to the catalytic oxidation action of the coated catalyst coating layer.
This does not normally occur with the ceramic resistor of the present invention. However, at high temperatures, the oxidation reaction of the ceramic resistor by the catalyst coating layer begins to proceed and the resistance value changes, so the reaction between the catalyst coating layer and the honeycomb heating element is prevented between the catalyst coating layer and the honeycomb heating element. It is desirable to provide an oxidation reaction preventive layer. Further, since the conductive electrode is made of metal, it is not preferable to directly contact with the catalyst coating layer because of the problem of corrosion. In the present invention, the catalyst coating layer is formed so as to be separated from the conductive electrode, or when the catalyst coating layer is provided even on the conductive electrode, an oxidation reaction preventive layer is provided between the catalyst coating layer and the conductive electrode. Is desirable.

Materials used for the oxidation-preventing layer include glass, silica, alumina, titania, titanocarbosilane, and perhydropolysilazane, and one or more of these may be used in a single layer or multiple layers. Among these materials, silica and titanocarbosilane are excellent and desirable from the viewpoint of adhesion between the oxidation reaction preventing layer and the ceramic resistor and the catalyst coating layer.

Alumina used in the catalyst coating layer of the present invention is
It is a metastable alumina such as β-, γ-, δ-, θ-, η-, ρ-, and χ-alumina. Further, by supporting a promoter such as a rare earth oxide on the surface of alumina, further increase in activity can be expected.

Further, as the inorganic binder, silica is the most excellent as a binder and forms a film which is not easily peeled off from the resistor when the catalyst coating layer is formed on the surface of the ceramic resistor without deteriorating the catalytic properties. be able to.

The content of silica of the present invention is preferably 10 to 40 wt% in the catalyst coating layer. When the content of silica exceeds 40 wt%, cracks are likely to be formed in the catalyst coating layer and the adhesion is likely to be deteriorated. On the other hand, if it is less than 10 wt%, a sufficient effect of improving adhesion of silica cannot be obtained.

Noble metals used in the present invention include Pt and P
There are d, Rh, and Ru. Of these, Pt is preferable because it has an excellent odor adsorption capacity as compared with other noble metals, and it is more preferable to use both Pt and Pd because of the oxidative decomposition ability of odor. This is because the oxidative decomposition power of Pt or Pd is higher than that of Rh or Ir, and the use of both Pt and Pd further enhances the activity. In addition, Ru
When used at high temperatures, Ru is volatilized and becomes a harmful substance.

It is desirable that the catalyst coating layer of the present invention contains copper oxide. This is because coexistence of copper oxide with the platinum group metal in the catalyst coating layer can prevent deterioration of the odor adsorption performance of the platinum group metal at high temperatures. Especially copper oxide,
It is most effective to use it in the state of activated alumina carrying a noble metal and copper oxide.

It is desirable that the zeolite of the present invention contains at least a pentasil-type zeolite. This is because the adsorption performance of odors that are difficult to adsorb such as aldehyde and dimethyl disulfide can be improved. Of the pentasil-type zeolites, H-ZSM5 and Na-ZSM5 are particularly preferable because they have a particularly high adsorption performance for the hardly adsorbed odor.

It is desirable that the zeolite of the present invention contains at least mordenite or Y-type zeolite. This is because the adsorption capacity for the odor of amines in the catalyst coating layer can be improved by including mordenite or Y-type zeolite.

It is desirable that the zeolite contains at least copper ion exchanged zeolite or iron ion exchanged zeolite. This is because when the catalytic oxidative decomposition of odors of the adsorbed amines is carried out, the catalyst coating layer contains copper ion-exchanged zeolite or iron ion-exchanged zeolite to suppress the production of nitrogen oxides and to obtain a high level of safe conversion to nitrogen. Because it will be done.

It is desirable to include cerium oxide in the catalyst coating layer of the present invention. By including cerium oxide in the catalyst coating layer, 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 coating layer. When the content of cerium oxide exceeds 15 wt%, the oxidative decomposition characteristics of the catalyst begin to decrease, and when the content is less than 2 wt%, a sufficient effect of adding cerium oxide cannot be obtained.

It is desirable to include barium oxide in the catalyst coating layer of the present invention. By including barium oxide in the catalyst coating layer, the oxidative decomposition characteristics of the catalyst can be improved.

The content of barium oxide of the present invention is preferably 0.5 to 5 wt% in the catalyst coating layer. If the content of barium oxide exceeds 5 wt%, the adhesion of the catalyst coating layer will deteriorate, and if it is less than 0.5 wt%, a sufficient effect of adding barium oxide cannot be obtained.

The same effect can be obtained by using barium carbonate instead of barium oxide of the present invention. The desirable addition amount of barium carbonate is 0.5 to 5 wt% in terms of barium oxide amount.

Various methods can be used for the method of forming the catalyst coating layer of the present invention. For example, there are spray coating, dip coating, electrostatic coating method and the like.

Next, the operation of the present invention will be mainly described.

In the present invention, since the catalyst coating layer is provided on the surface of the honeycomb ceramic resistor, the honeycomb ceramic resistor is electrically heated, and at the same time, not only the human body or the object to be heated but also the catalyst coating layer is heated. Become. Here, since the catalyst coating layer covers the periphery of the resistor, heat is efficiently absorbed from the resistor by heat transfer, and the catalyst coating layer is heated to the activation temperature of the catalyst in a short time. When the air near the heating element comes into contact with the catalyst heated above the activation temperature,
Odorous components in the air, such as ammonia and fatty acids, are catalytically oxidized and purified by the catalytic action.

Furthermore, by incorporating zeolite or a noble metal having excellent adsorption properties into the catalyst coating layer, it is possible to adsorb odorous substances when the electric resistor is not energized. In this case, when the adsorption capacity of zeolite or noble metal reaches saturation, by energizing the ceramic resistor, oxidative decomposition of the adsorbed odorous component by catalyst and regeneration of zeolite can be performed.

As described above, the deodorizing ability can be maintained for a long period of time by normally adsorbing the odorous substance at room temperature and intermittently energizing the heating element.

The above operation has been described for the case of natural convection that occurs in the vicinity of the heating element, but a more remarkable effect can be obtained when the air is forcibly supplied to the heating element by a fan or the like.

[0031]

BEST MODE FOR CARRYING OUT THE INVENTION An embodiment of the present invention will be described below with reference to FIG. In FIG. 1, 1 is a SiC honeycomb as a ceramic honeycomb resistor, 2 is a conductive electrode, 3 is a catalyst coating layer, 4 is an oxidation reaction preventing layer, and 5 is an air flow.

When the conductive electrode 2 is energized, the SiC honeycomb 1 generates heat and is stabilized at a temperature corresponding to the applied power. Even if the amount of applied electric power is increased to raise the temperature of the SiC honeycomb 1, the resistance change is suppressed because the oxidation reaction preventive layer 4 is provided on the surface of the SiC honeycomb 1.

When the SiC honeycomb 1 is not energized, the odorous components in the room are usually adsorbed and deodorized by the zeolite and the noble metal in the catalyst coating layer 3. When the SiC honeycomb 1 is energized before adsorbing the odorous components to the limit of the odor adsorption capacity of the catalyst coating layer 3, heat is transferred from the SiC honeycomb 1 to the catalyst coating layer 3 installed so as to cover the outer periphery. The heating is performed efficiently, and the catalyst can be heated to its activation temperature in a short time. The odorous components adsorbed on the catalyst coating layer 3 are oxidized and purified by the activated catalyst. Further, since the heating element also heats the air in the vicinity thereof, an air flow 5 is generated as convection near the heating element. And this air flow 5
When it comes into contact with the catalyst coating layer 3 heated to the activation temperature by heating or diffuses into the coating layer, odors and harmful components contained in the air stream 5, such as carbon monoxide (hereinafter CO 2
And ammonia are purified by the catalytic action.

Therefore, even if odors, cigarette smoke, and harmful gases such as CO drift in the atmosphere in which the heating element is placed, they can be purified during heating or use, and a comfortable environment can be created.

[0035]

EXAMPLE A more specific example of the present invention will be described below. <Example 1> Length 100 mm, width 100 mm, thickness 10 m
A SiC honeycomb-shaped resistor having a cell density of 100 cells / in ² at m was used, and a copper electrode was formed by thermal spraying as a conductive electrode in the configuration as shown in FIG. Next, a resistor A of the present invention in which a siliceous oxidation-preventing layer having a thickness of about 60 μm was formed on the resistor by using silica sol except for the copper electrode portion, and a resistor B in which the oxidation-preventing layer was not formed Was prepared.

400 g of γ-alumina and an inorganic binder
As colloidal alumina 1000 with an alumina content of 10 wt%
g, copper ion exchanged A-type zeolite 500 g, water 15
A slurry A was prepared by adding 00 g, 30 g of chloroplatinic acid as Pt, 30 g of palladium chloride as Pd and 15 g and an appropriate amount of hydrochloric acid, and thoroughly mixing with a ball mill.
The heating element A and the heating element B were prepared by applying the slurry A to the resistor A and the resistor B, respectively, to form a catalyst coating layer. The catalyst coating amounts were both 5.0 g.

Further, a nichrome wire as an electric resistor and an insulator having an outer diameter of 10 mm, an inner diameter of 9 mm and a length of 15 c.
One set of 5 m quartz tubes, length 100 mm, width 100 mm,
Honeycomb SU with a thickness of 10 mm and a cell density of 100 cells / in ²
Comparative heating elements A and B in which 5.0 g of the catalyst coating layer was formed on each of the S430 resistors using the slurry A were prepared.

A mercaptan oxidation purification test and a durability test were performed on these heating elements. In the methyl mercaptan oxidation purification test, the heating element is placed in a cubic resin container made of fluorine resin of 0.5 m ³ and the center of the heating element is blown by blowing air inside the container at a flow rate of 50 l / min to the heating element. It was carried out by injecting methyl mercaptan into the container so that the concentration became 10 ppm to the place where electricity was applied so that the temperature of the outer surface of was about 450 ° C., and checking the change in the concentration of methyl mercaptan in the container after 20 minutes of electricity application. The change with time of the methyl mercaptan concentration was examined by gas chromatography. The endurance test is conducted by energizing the temperature of the outer surface of the center of the heating element to 450 ° C. in 40 ° C. air, maintaining the temperature for 10 minutes, stopping energizing, cooling for 20 minutes, and then energizing again. After repeating the energization cycle of 1000 times, the presence or absence of abnormality in the catalyst coating layer was examined. The results are shown in (Table 1).

[0039]

[Table 1]

As is clear from (Table 1), the heating elements A and B of the present invention have a mercaptan oxidation purification property and a comparative heating element A which is a quartz tube heating element and a comparative heating element B which is a metal heating element. It had excellent durability. 90% relative humidity
In the same test as the above durability test in air, no abnormalities were found in the heating elements A and B and the comparative heating element A, whereas the catalyst coating layer peeled off on the comparative heating element B which is a metal heating element. Not only that, remarkable rusting was observed.

Next, the heating elements A and B are heated to 50 l / m by a fan.
While blowing the air in the container at a flow rate of in to the heating element, it was placed in a closed box with a volume of 0.5 m ³ whose inner wall surface was covered with fluorine resin, and the air-diluted methyl mercaptan at a concentration of 10 ppm was not energized. And the amount of residual methyl mercaptan was measured 30 minutes after the heating element was put in and the amount of residual methyl mercaptan was measured. The amount of residual methyl mercaptan is 7% for both
The deodorization was promptly performed. <Example 2> The heating element A and the heating element B prepared in Example 1 were energized to apply a power load such that the temperature of the heating element reached 500 ° C, and the change in resistance after 1000 hours of continuous energization was measured. The results are shown in (Table 2).

[0042]

[Table 2]

As is clear from (Table 2), the resistance value of the heating element A having the antioxidant layer did not change, but the resistance value of the heating element B having no oxidation layer changed. From this result, when forming the catalyst coating layer, it is desirable to provide an oxidation reaction prevention layer between the catalyst coating layer and the honeycomb heating element to prevent the reaction between the catalyst coating layer and the honeycomb heating element.

When the heating element B is energized and the heating element temperature is 300
No change in resistance value is observed after 1000 hours of continuous energization under a power load of 0 ° C., and the oxidation reaction preventive layer is not necessary at a relatively low temperature. <Example 3> A heating element having the same structure as that of the heating element A was prepared by variously changing the material of the conductive electrode as shown in (Table 3). The initial resistance value of each heating element was 5.0 Ω. Next, each heating element was energized and an electric load was applied so that the temperature of the heating element reached 700 ° C., and the resistance value after 1000 hours of continuous energization was measured. The results are shown in (Table 3).

[0045]

[Table 3]

As is clear from (Table 3), nickel,
Copper, brass, silver-Pt, silver-Pd, and Pt are desirable because they have little resistance change. In particular, silver-Pd / brass and silver-Pt / brass do not change in resistance value, and it is desirable that the conductive electrode has a two-layer structure. <Example 4> A heating element having the same structure as that of the heating element A was prepared by changing the material of the antioxidant layer as shown in Table 4 below. A thermal shock test was performed on these heating elements to examine the adhesion of the catalyst coating layer. In the thermal shock test, the heating element is energized, the temperature of the catalyst coating layer is set at every 25 ° C., the temperature is maintained for 10 minutes, and then the temperature is dropped in room temperature water to check whether the catalyst coating layer is peeled off. The maximum temperature that does not cause the heat resistance was defined as the thermal shock resistance temperature. The results are shown in (Table 4).

[0047]

[Table 4]

As is clear from Table 4, silica and titanocarbosilane are desirable because of their high thermal shock resistance temperature. Further, when a two-layered antioxidant layer having silica as the upper layer and titanocarbosilane as the lower layer is provided, the thermal shock resistance temperature is 750.
The temperature was ℃ and good results were obtained. Titanocarbosilane has the most excellent moisture resistance among the antioxidant layer materials shown in (Table 4). Due to such two layers, the antioxidant layer is excellent in both moisture resistance and adhesion of the catalyst coating layer. Is obtained and desirable. <Example 5> A heating element having the same configuration as that of the heating element A was prepared by variously changing the method of forming the conductive electrode as shown in (Table 5). The initial resistance value of each heating element is shown in (Table 5).

[0049]

[Table 5]

As is clear from (Table 5), the spraying method is preferable as the method for forming the conductive electrode because it has the lowest resistance value. <Example 6> In the slurry A of Example 1, the slurry 1 containing no platinum group salt, the platinum group salt containing no γ, and γ
-Similar to the heating element A, using a slurry 2 in which alumina is all copper ion-exchanged A-type zeolite and a slurry 3 which does not contain a platinum group salt and in which copper ion-exchanged A-type zeolite is all γ-alumina. Heating elements C, D, and E having 5.0 g of each catalyst coating layer were prepared.

An acetic acid adsorption test was performed on the heating elements C, D, and E, and the acetic acid residual rate 60 minutes after the start of measurement was compared with that of the heating element A. In the acetic acid adsorption test, the heating element was placed in a cubic fluorine resin container of 0.5 m ³ and the heating element was not heated, while the air inside the container at a flow rate of 50 l / min was blown to the heating element. Then, acetic acid was injected into the container so that the concentration became 40 ppm, and the change of the concentration with time was examined. The change with time of the acetic acid concentration was examined by gas chromatography.

The results are shown in (Table 6). As is clear from (Table 6), the heating element A of the present invention was superior to the heating elements C, D and E in the adsorption characteristics of acetic acid which is an acidic odor component. Therefore, by using activated alumina, zeolite, and platinum group metal at the same time, it is possible to obtain a synergistic effect of improving the adsorption characteristics for acidic odor components, compared with the case of using activated alumina or zeolite alone.

[0053]

[Table 6]

Example 7 400 g of γ-alumina, 1000 g of colloidal alumina having an alumina content of 10 wt% as an inorganic binder, copper ion-exchanged A-type zeolite 450
g, copper oxide 50 g, water 1500 g, chloroplatinic acid as Pt
As a slurry 4 was prepared by adding 30 g, palladium chloride as Pd and 15 g and an appropriate amount of hydrochloric acid, and thoroughly mixing using a ball mill.

A slurry 5 similar to the slurry 4 was prepared by using an aqueous solution of chloroplatinic acid, palladium chloride, and alumina in which Pt, Pd, and CuO were preliminarily carried by using the same composition component as the slurry 4. Further, a slurry 6 was prepared in which the precious metal content of the slurry 4 was changed to copper oxide.

Example 1 using the slurries 4, 5 and 6
Heating elements F, G, and H were prepared from the same method and the same ceramic resistor.

In order to compare the heating elements F, G and H with the heating element A, a methyl mercaptan purification test was conducted. In the methyl mercaptan purification test, the heating element was placed in a cubic container made of fluorine resin of 0.5 m ³ and 50 l /
While blowing air in the container at a flow rate of min to the heating element, methyl mercaptan was injected into the container so that the concentration became 8 ppm, and 90 minutes later, the concentration of methyl mercaptan was examined. The heating element was not heated and the measurement was carried out by gas chromatography. Further, after the adsorption test, the heating element was heated in air at 700 ° C. for 20 hours, cooled to room temperature, and again subjected to a methylmercaptan purification test to examine the heat resistance of the deodorant. The results are shown in (Table 7).

[0058]

[Table 7]

As is apparent from (Table 7), the heating element to which only the noble metal or only the copper oxide is added is 700 ° C.
However, the heat resistance of the deodorant can be improved by adding both copper oxide and a noble metal. Further, it is desirable that both copper oxide and a noble metal are supported on alumina in advance and the heat resistance is further improved. <Example 8> In the slurry-A of Example 1, a slurry in which the copper ion-exchanged zeolite was all replaced with various zeolites shown in (Table 7) was prepared to prepare a heating element having the same configuration as the heating element A. did.

Further, in the slurry A of Example 1, slurry having the same total amount of noble metal components but Pt only, Pd only, Rh only, and Ru only was prepared, and a heating element having the same structure as the heating element A was prepared. It was created.

The adsorbing properties of trimethylamine and acetaldehyde having a hardly adsorbed odor were tested on these heating elements. In the odor adsorption test, the heating element was placed in a cubic fluorine resin container of 0.5 m ³ and the heating element was not heated, but the air inside the container at a flow rate of 50 l / min was blown to the heating element. , Trimethylamine, and acetaldehyde were injected into the container so that the concentration was 10 ppm, and the odor residual rate in the container after 60 minutes of adsorption was evaluated. The odor concentration in the container was examined by gas chromatography. The results are shown in (Table 8) and (Table 9).

[0062]

[Table 8]

As is clear from Table 8, pentasil type zeolite, Y type zeolite, mordenite, Cu-
The A-type zeolite was excellent in the adsorption property of both acetaldehyde and trimethylamine. Further, among the zeolites, pentasil-type zeolite ZSM5 and silicalite are preferable due to their acetaldehyde adsorption property, and particularly H
-ZSM5 and Na-ZSM5 are the most desirable and desirable. Further, Y-type zeolite and mordenite are excellent in the adsorption property of trimethylamine, and are desirable. Zeolites are selected according to the target odor to be deodorized. Further, it is desirable that a mixture of pentasil-type zeolite and Y-type zeolite or mordenite is used because it is possible to obtain one having excellent adsorption properties for both acetaldehyde and trimethylamine.

[0064]

[Table 9]

As is clear from Table 9, Pt--Pd and Pt among the noble metals have excellent acetaldehyde adsorption properties, and it is desirable that Pt be contained as the noble metal component. <Example 9> The oxidative decomposition performance of trimethylamine was measured using heating elements having different zeolite species shown in Table 8. In the measurement, a helium dilution gas containing 1000 ppm of trimethylamine and 21% of oxygen was passed through each heating element heated at 300 ° C. at SV 5000 h ⁻¹ , and the nitrogenation rate at the time of oxidative decomposition of trimethylamine by the heating element was evaluated. The results are shown in (Table 10).

[0066]

[Table 10]

As is clear from Table 10, copper ion-exchanged zeolite and iron ion-exchanged zeolite are desirable because of their high nitrogenation rate. The concentration of trimethylamine contained in the air as an odor is usually low, and it does not matter if nitrogen oxides are produced, but in an environment where the amount of produced nitrogen oxides is large, it is preferable to use copper ion exchanged zeolite or iron ion exchanged zeolite. Further, the copper ion-exchanged zeolite and the iron ion-exchanged zeolite are also excellent in the adsorption property of acetaldehyde and trimethylamine as shown in (Table 8).

[0068]

As is apparent from the above description,
According to the present invention, it is possible to provide a honeycomb heating element capable of increasing and decreasing the heat output from the heater without a cooling means, having a high ability to remove harmful and unpleasant components, and capable of efficiently deodorizing in a short time.

[Brief description of drawings]

FIG. 1 is a schematic view showing a typical example of the present invention.

[Explanation of symbols]

 1 SiC honeycomb heating element 2 Conductive electrode 3 Catalyst coating layer 4 Oxidation reaction prevention layer 5 Air flow

 ─────────────────────────────────────────────────── ─── Continuation of front page (72) Inventor Kimoyasu Honda 1006 Kadoma, Kadoma City, Osaka Prefecture Matsushita Electric Industrial Co., Ltd. (72) Kunio Kimura, 1006 Kadoma, Kadoma City, Osaka Matsushita Electric Industrial Co., Ltd.

Claims (14)

[Claims] 1. At least a substantially rectangular columnar or substantially square plate-shaped and honeycomb-shaped ceramic resistor, and a conductive electrode formed on a pair of outer peripheral surfaces facing each other of the honeycomb body.
A heating element comprising: a catalyst coating layer covering the surface of the honeycomb-shaped ceramic resistor. 2. The heating element according to claim 1, wherein an oxidation reaction preventing layer is provided between the catalyst coating layer and the honeycomb-shaped ceramic resistor and / or the conductive electrode. 3. The heating element according to claim 2, wherein the oxidation reaction preventive layer comprises at least one selected from glass, silica, alumina, titania, titanocarbosilane, and perhydropolysilazane. 4. The heating element according to claim 1, wherein the honeycomb-shaped ceramic resistor is SiC. 5. The heating element according to claim 1 or 2, wherein the catalyst coating layer comprises at least activated alumina, a platinum group metal, zeolite and an inorganic binder. 6. The heating element according to claim 1, wherein the catalyst coating layer contains copper oxide. 7. The heating element according to claim 1, 2 or 5, wherein the catalyst coating layer contains activated alumina carrying a noble metal and copper oxide. 8. The heating element according to claim 5, wherein the zeolite contains at least a pentasil-type zeolite. 9. The heating element according to claim 5, wherein the zeolite contains at least mordenite or Y-type zeolite. 10. The heating element according to claim 5, wherein the zeolite contains at least copper zeolite. 11. A pentasil-type zeolite is H-ZSM.
The heating element according to claim 8, comprising at least one selected from the group consisting of 5, Na-ZSM5. 12. The inorganic binder is silica.
The heating element described. 13. The heating element according to claim 5, wherein the platinum group metal contains at least Pt. 14. The conductive electrode is made of aluminum, nickel, copper,
The heating element according to claim 1, comprising at least one selected from brass, silver-Pd, silver-Pt, and Pt.