JPH03131348A - Self-heating type catalyst apparatus - Google Patents

Abstract

PURPOSE:To miniaturize and simplify a catalytic apparatus and to enhance catalytic effect by forming a catalyst carrier itself from a heating body. CONSTITUTION:A catalyst carrier C itself is formed of a heating body. As the catalyst carrier C, a material having a high electric specific resistance value is used and a catalyst is supported on this material. As this material, two kinds of the following materials are proper. That is, one of them is an Fe-Cr-Al alloy consisting of 10-30% Cr, 2-20% Al and the remainder Fe and the other one is a material having a surface composition consisting of 10-30% Cr, 6-20% Al and the remainder Fe and having alumina whiskers formed to the surface thereof. As the structure of the catalyst carrier C, a honeycomb structure is pref. As a result, a catalyst apparatus can be miniaturized and simplified and catalytic effect can be enhanced.

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention relates to a catalyst device for deodorization and oil combustion used in various regulating devices, combustion devices, and the like.

(Prior Art) Catalyst devices for deodorizing or decomposing oil smoke are installed in various cooking appliances such as microwave ovens and combustion devices such as fan heaters. These catalytic devices are made by supporting a catalytic material tailored to the purpose on a carrier made of ceramic or metal with a honeycomb structure, and installing it in the exhaust system of a cooking appliance or combustion device to convert the circulating gas into catalytic material. Through the catalytic action of oxidative decomposition, reductive decomposition, deodorization, oil smoke decomposition, etc., the purpose is achieved.

Catalyst devices usually need to be heated to a temperature of about 300° C. in order to perform their catalytic action efficiently and economically. Currently, catalyst devices are equipped with heating devices to maintain catalyst efficiency. The catalyst material and the carrier are maintained at a predetermined temperature by this heating device, and function effectively as a catalyst device.

(The problem that J. Ming is trying to solve) However, such conventional catalyst devices require a heating device, so a heating element is installed inside the catalyst device in addition to the catalyst carrier, which increases the size of the device. There were also problems with economic efficiency. In addition, since the catalyst carrier is heated from the outside by a heating element, there is a drawback that there is a large loss in catalyst efficiency due to temperature distribution or the time it takes for the catalyst to reach a predetermined temperature to become effective. .

As a result of studies to solve the above problems, the present inventors discovered that the catalyst carrier itself can be used directly as a heating element due to the characteristics of the material used for the catalyst carrier, and have completed the present invention. SUMMARY OF THE INVENTION An object of the present invention is to provide a catalyst carrier that can miniaturize and simplify catalyst devices used in cooking appliances and combustion devices, and that can operate efficiently.

(Means for Solving the Problems) The gist of the present invention is a self-heating type catalyst device characterized in that the catalyst carrier itself is a heating element.

That is, in the present invention, a material having a high electrical resistivity value is used as the catalyst carrier, and the catalyst is supported on this material. Then, by making, for example, a honeycomb structure using the carrier supporting this catalyst and heating the structure with electricity, the desired temperature can be easily achieved, and high catalytic efficiency can be achieved in a small space. It can be a catalyst device having a

Therefore, in the present invention, carriers that can be used include:
It is a material that has a high electrical resistivity as well as the ability to support a catalyst. The following two types of materials are suitable as such materials.

I") is a Fe-Cr-A Q alloy consisting of 10~30% Cr, 12~20% Al, balance Fe.This alloy forms a dense alumina film on the surface when heated in the atmosphere. Therefore, it has excellent oxidation resistance and catalytic material support properties.
It also has a high electrical specific resistance value. In this alloy, it is preferable to add elements such as REM, Y, Zr1Ti, Ca, and B in order to further improve hot workability, oxidation resistance, and alumina film adhesion. The reason why the component range of the present alloy is determined as described above is to provide a high electrical resistivity value and oxidation resistance within a range that does not impair workability.

The other material has a surface composition of 10 to 30% Cr, 12 to 20% Al, balance Fe, and has an alumina 3-scar formed on its surface. This material was disclosed by the inventor in his earlier Japanese Patent Application No. 1-101755. In this case, a higher electrical resistivity can be obtained even with the same composition due to the effect of strain between the alumina whiskers and the material surface, which is advantageous when the catalyst is operated at a higher temperature.

Although the structure of the catalyst carrier is not particularly limited, a honeycomb structure is preferable. Although there are no restrictions on the formation of the honeycomb structure, it is preferable to form the honeycomb structure by alternately overlapping flat plates and corrugated plates for simplicity of structure and formation. From the viewpoint of electrical resistance, it is desirable that the honeycomb structure has a small cross-sectional area and a long length, but if there is a restriction on installation space, a plurality of appropriately sized honeycomb structures can be stacked one on top of the other. When molding a honeycomb structure or when using a plurality of honeycomb structures stacked one on top of the other, insulation may be required partially. However, since the material used in the present invention is a Fe-Cr-Aα alloy, high insulation can be maintained due to the presence of the highly insulating alumina film 4- on the surface.

Hereinafter, the present invention will be explained in more detail with reference to Examples.

Example 1 A honeycomb structure as shown in FIG. 1 was created using a 50 μm thick Fe-20%Cr-5%Al ferritic stainless steel foil. Dimensions are 20mm x honeycomb structure
20ynm x 160+n+n, cell density 150 pcs/
The joints between the corrugated plate and the flat plate were made using brazing.The electrical resistivity value of this material at room temperature was 148 μΩ・c.
It was m.

There was a gap 180c+n between both ends of this honeycomb structure, and a current of 50H7 AC and IL 45A was passed through both ends to heat the honeycomb structure to 200°C. A temperature measurement point was provided at the center of the honeycomb structure, and the temperature change at the measurement point after the power was turned on was measured, and the results shown in FIG. 2 were obtained. It can be seen from FIG. 2 that the temperature reaches 200° C. with an extremely rapid rise.

In addition, the gap between the picture electrodes is divided into 6 equal parts, and each position is designated as measurement points 1 to 5. Measurement points 1 to 5 are measured 2 minutes after the power is turned on.
When I measured the temperature in 5, it was 200℃, 204℃
, 206°C, 205°C, and 203°C showed a uniform distribution. Furthermore, the purification rate was measured by flowing propylene gas, but 1
We were able to obtain a purification rate of 0.00%.

Example 2 The surface of Fe-20%Cr-5%Al ferritic stainless steel was plated with l by the mechanical brating method described in Japanese Patent Application No. 63-299714, and heated at 800°C.
It was heated in a vacuum atmosphere of 2×1O-Torr for 1 minute, and then heat-treated in an air atmosphere of 900° C.×16)1r to generate whiskers. The electrical resistivity value of this material at room temperature was 210 μΩ·CI+. Example 1 using this
A honeycomb structure was made in the same manner as above, and an electric current was applied.

At this time, the temperature at measurement point 3 rose to 280°C. In addition, the temperatures at measurement points 1 to 5 are 278°C, 280°C, and 276°C.
℃, 282℃, and 280℃, showing a uniform distribution.

The propylene gas purification rate at this time was 100%, which was good.

(Effects) By forming the catalyst carrier into a honeycomb structure using a self-heating type Fe-Cr-AQ alloy, the following effects can be achieved.

(1) No need for a heater. (2) Since heating is performed by electrical current, the temperature of the catalyst carrier can be raised faster than when using a heater.

(3) The temperature distribution of the catalyst carrier becomes more uniform than when a heater is used, and as a result, the effectiveness of the catalyst is improved.

(4) When whiskers are generated on the surface, even honeycomb structures of the same size have a high electrical resistivity value and can achieve higher temperatures.

(5) When the catalytic material is supported by alumina whiskers, the number of catalytic active sites that contribute to catalytic action increases, improving the effectiveness of the catalyst.

(6) When applying electricity to both ends of a honeycomb structure, it is basically a parallel circuit, and the resistance value is determined by the cross-sectional area and length. structure can be determined. For example, it is also possible to use a divided arrangement of a honeycomb structure or a structure that takes advantage of its insulation properties.

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[Brief explanation of the drawing]

FIG. 1(i) is a side view of the catalyst device according to the present invention, and FIG. 2 shows the results of temperature rise measurement of the catalyst device in Example 1.

Claims (1)

[Scope of Claims] 1. A self-heating type catalyst device characterized in that the catalyst carrier itself is a heating element. 2. Catalyst carrier is 10-30% Cr, 2-20% Al
2. The self-heating type catalyst device according to claim 1, wherein the self-heating type catalyst device is an Fe-Cr-Al alloy consisting of , the balance being Fe. 3. Catalyst carrier is 10-30% Cr, 6-20% Al
2. The self-heating type catalyst device according to claim 1, wherein the material has a surface composition with the remainder being Fe and has alumina whiskers formed on its surface. 4. The self-heating type catalyst device according to claim 1, wherein the catalyst carrier constitutes a honeycomb structure.