JPH06129616A - Element for catalyst combustion - Google Patents

Abstract

PURPOSE:To provide an element for catalyst combustion in which it has a high mechanical strength and has a high heat transfer rate so that a partial high temperature can hardly occur. CONSTITUTION:An active metal 3 acting as a combustion catalyst is coated on a surface of a porous member 2 comprised of metallic long fibers acting as its base. With such an arrangement, a reduction of activation caused by sintering is prevented and then an element for catalyst combustion having a high active area per unit volume can be attained. Formation of various shapes can also be attained.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a catalytic combustion element, and more particularly to a low temperature catalyst which utilizes a combustion heat and a radiant heat generated by the catalytic reaction of a supplied fuel gas and oxygen on a catalytic body. The present invention relates to a catalytic combustion element suitable for use in a combustion burner.

[0002]

2. Description of the Related Art Combustible fuel gas such as methane, methane-containing gas, LPG and oxygen are catalytically reacted with each other on a catalytic body to burn flamelessly at a low temperature so as not to generate a flame, thereby generating combustion heat and A low-temperature catalytic combustion burner that uses radiant heat produces less NO _X , CO, etc., less fire hazard, high far-infrared radiation efficiency, uniform combustion surface temperature, and low load. Since it has advantages such as stable combustion, it has been widely used as a heating means at a relatively low temperature for household and commercial purposes.

As a catalytic combustion element used as the combustion surface of such a low-temperature catalytic combustion burner, as shown in FIG. 2 (A), a ceramic washcoat layer 5 is formed on a base made of a ceramic honeycomb 4. After the application, the active metal 6 serving as the catalyst is supported in the form of particles, or, as shown in FIG. 2B, the active metal 6 serving as the catalyst is provided on the ceramic fiber 7 for forming the substrate. Those directly supported in the form of particles have been known (Japanese Patent Laid-Open Nos. 51-83088 and 5).
6-62542, etc.).

[0004]

However, in the above-described conventionally known element for catalytic combustion, since the ceramic is the base, there is a problem in the mechanical strength thereof, and the heat of the ceramic that is the base is problematic. Since the conductivity is low, there is a problem that it is difficult to avoid the occurrence of a partial high temperature portion (HOT SPOT) on the combustion surface when the fuel supply is uneven.

Further, although there is one in which a combustion element is formed by an active metal itself (for example, platinum wire) serving as a catalyst, in such a case,
It is economically problematic that the amount of precious metal such as platinum that is an active metal increases, and it is necessary to produce a porous body to obtain a high surface area only with such an active metal.
It is technically difficult.

The present invention solves the above problems and, compared to conventional ceramic-based catalytic combustion elements,
Not only the mechanical strength is high, but also the high thermal conductivity makes it difficult for a high temperature part (HOT SPOT) to occur.
Provided is a combustion catalyst body capable of preventing a decrease in activity due to sintering due to this, a large active surface area per unit volume, a small pressure loss at the time of fuel supply, and easily manufacturing various shapes. The purpose is to do.

[0007]

SUMMARY OF THE INVENTION In order to solve the above-mentioned problems and to achieve the object, the present invention has an active metal serving as a combustion catalyst on the surface of a porous body made of metal long fibers as a base. Provided is an element for catalytic combustion, which is characterized by being coated.

[0008]

In the catalytic combustion element according to the present invention having the above-mentioned structure, the porous body which is the base is formed by the aggregate of the metal long fibers, and therefore, compared with the conventional ceramic-based one. , The mechanical strength is improved. Even if the fuel supply is uneven, the base is made of metal and has a high thermal conductivity, so that a partial high temperature portion (HOT SPOT) is unlikely to occur, and such a partial high temperature portion is not generated. The occurrence of sintering due to the appearance of is prevented.

Further, the pressure loss when the fuel gas is permeated and supplied from the back side of the combustion catalyst is small, and
Since the fiber surfaces of the long metal fibers are all catalytic surfaces and a high active surface area can be obtained, the combustion is efficiently performed. Furthermore, because of the characteristics of the porous metal body, it is possible to freely select various desired shapes such as a cylindrical shape as well as a plate-like shape. Be done.

[0010]

EXAMPLES The present invention will now be described in more detail based on the description of examples. As the metal long fibers constituting the base of the element for catalytic combustion according to the present invention, for example, metal long fibers of iron, chromium, nickel, aluminum or the like having a fiber diameter of 20 to 50 μm and a porosity of 70 to 95% are used. A sintered product is preferably used.

As shown in FIG. 1, such a long metal fiber 2 is used.
On the other hand, the active metal 3 such as palladium, platinum, nickel, cobalt, rhodium or the like is coated on the entire surface to a thickness of about 5 to 10 μm by a method such as electrolytic or electroless plating. As the method for plating the active metal on the long metal fibers in the present invention, the plating method disclosed in Japanese Patent Application Laid-Open No. 3-146122 filed by the same applicant as the present invention is effectively used.

Concrete Example A metal fiber made of iron, chromium, silicon, aluminum, and yttrium having a fiber diameter of 22 μm was sintered to a porosity of 80%, and platinum was plated by an electroless method to a thickness of about 5 μm. To produce an element for catalytic combustion. The composition of the plating solution is: Pd (NH ₃ ) ₄ Cl ₂ · H ₂ O 5.4 g / l 2NaEDTA 67.2 g / l NH ₃ (28% aqueous solution) 651.3 ml / l H ₂ NNH ₂ · H ₂ O 0.46 ml / l And was plated at pH 11.3 and 50 ° C. for 5 hours.

The obtained element for catalytic combustion was formed into a plate and used as a combustion surface of a low temperature catalytic combustion burner.
As compared with the conventional ceramic-based catalyst body, one having a large mechanical strength, a high thermal conductivity, a small pressure loss during fuel supply, and a large active surface area per unit volume was obtained. In addition, as shown in FIG.
The combustion was effectively performed in both cases of the parallel flow as shown in Fig. 3 and the vertical flow as shown in Fig. 3B.

[0014]

The element for catalytic combustion according to the present invention is
Compared to the conventional ceramic-based fuel element, the mechanical strength is high and the thermal conductivity is high, so that a high temperature part is less likely to occur. Therefore, a decrease in activity due to sintering due to this is prevented. Further, since the pressure loss during fuel supply is small and the active surface area per unit volume is large, efficient combustion can be performed.

Further, since various shapes can be easily produced without increasing the amount of the active metal used, the combustion catalyst can be effectively heated with a shape suitable for the object to be heated. .

[Brief description of drawings]

FIG. 1 is an explanatory view of a catalytic combustion element according to the present invention.

FIG. 2 is a partially enlarged explanatory view of a conventional catalytic combustion element.

FIG. 3 is an explanatory view showing the flow of fuel gas with respect to the catalytic combustion element according to the present invention.

[Explanation of symbols]

 2-Metal filaments 3-Active metals

Claims (1)

[Claims] 1. A catalytic combustion element, wherein the surface of a porous body made of metal long fibers as a base is coated with an active metal serving as a combustion catalyst.