JPH0545294B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION Field of Industrial Application The present invention provides a method for removing incompletely combusted components generated during combustion, unburned hydrocarbon components, or hydrocarbon components that cause odors generated during various types of cooking. The present invention relates to an exhaust gas purification catalyst provided therein.

Prior Art Conventionally, there have been various types of catalyst bodies of this type. In other words, the catalyst supporting platinum group metals, which is the most common among them, is made by impregnating a porous ceramic carrier with an aqueous solution containing platinum group metals, such as an aqueous solution of chloroplatinic acid, and then drying and firing it. It is attached to the surface of the pores as fine metal particles or fine metal oxide particles. Although platinum group catalysts have good activity, their disadvantage is that they are very expensive. It is known that transition metal oxides or perovskite composite oxides incorporating a portion of transition metals have activity comparable to that of platinum if the particle size is made very small, but transition metal oxides alone are unstable at high temperatures. However, some composite oxides with a perovskite structure have considerable activity and are also resistant. Therefore, if fine powder of these perovskite compounds is attached to a carrier, it becomes an excellent catalyst, but the attached fine powder inevitably has low strength and tends to partially fall off. Only a small portion of the perovskite compound falls off, which has little effect on activity deterioration, but after the perovskite compound, which is mostly black, falls off, the white carrier surface becomes exposed, which is aesthetically undesirable. In particular, it is necessary to solve this problem for household combustion equipment.

Problems to be Solved by the Invention As described above, conventional carriers are almost white or nearly white in color, and if the attached black powder falls off, it will be noticeable. The present invention has been made in view of this point, and its purpose is to make the carrier itself black or a color close to black in advance.

Means for Solving the Problems In order to solve the above problems, the present invention provides a honeycomb structure made of a heat-resistant ceramic material having micropores inside, and a honeycomb structure supported by the micropores of the honeycomb structure. Transition metal oxide fine particles that exhibit a black color when fired in air; fine particles of perovskite composite oxide that has oxidizing activity and are supported on the outer surface of the honeycomb structure; and transition metal oxide particles that have adhesive properties when fired. The honeycomb structure is composed of oxide fine particles and a supporting agent for supporting the fine particles of perovskite composite oxide on the honeycomb structure.

Effects The present invention has the above-described structure, so even if some of the supported catalyst powder is missing, no abnormality is observed in appearance. Further, since transition metal oxides are formed inside the pores of the catalyst carrier, the blackened catalyst carrier can greatly increase the catalytic oxidation ability compared to the non-blackened catalyst carrier.

Embodiment FIG. 1 is a model diagram showing an embodiment of the catalyst body of the present invention. In FIG. 1, a catalyst carrier 2 is a micropore existing in the catalyst carrier 1, and transition metal oxide fine particles 3 are supported on the inner wall surface thereof. A perovskite composite oxide 5 is strongly adhered to the outer surface 4 of the catalyst carrier 1 by alumina 6 formed by firing a supporting agent. As the supporting agent, a material such as colloidal alumina or aluminum nitrate, which becomes porous and has strong adhesive properties by firing, is used.

In the above structure, even if part of the film of perovskite composite oxide 5 and alumina 6 attached to the surface 4 of the catalyst body is lost due to some mechanical impact or contact, the underlying surface will remain black. There is no change in appearance at all.

An example of the method for producing this catalyst will be described below.

Fine particles of perovskite composite oxide (La _0.9
Ce _0.1 C ₀ O ₃ ) Cobalt nitrate (C ₀ (NO ₃ ) ₂・6H ₂ O)
and aluminum nitrate (Al(NO ₃ ) ₃ ·9H ₂ O) are mixed in a weight ratio of 4:3:2, and water is added to form a slurry. Furthermore, in order to stabilize the slurry, a small amount of CMC, PVA, etc. is added to adjust the viscosity to a specified level, and a cordierite honeycomb structure with micropores inside is immersed in the slurry. The immersed honeycomb structure is taken out, the slurry liquid remaining in the cells is blown away by wind pressure, dried at 100°C for about 1 hour, and then fired at 800°C for 5 to 10 minutes.

FIG. 2 is an example of the application of the catalyst carrier of the present invention, in which the catalyst body is mounted in a gas cooker.

A catalyst body 7 having a honeycomb shape is installed at an exhaust gas outlet 9 above an interior 8 of the cooking appliance. A wire mesh heating element 10 is placed on the top surface of the cooking chamber 8, and is heated to red heat by a gas burner 11.
Furthermore, a stand 13 for placing the food 12 to be cooked, a saucer 14 for receiving oil from the food 12, etc. are installed in the lower part of the interior 8 of the cooking appliance.

In the above cooker, the table 12 on which the food to be cooked 12 is placed
The gas burner 11 is placed on top of the device and the wire mesh heating element 10 is heated to red heat, and the food 12 is cooked by the radiation and hot exhaust gas generated from the wire mesh heating element 10. At this time, odor-containing hydrocarbons generated from the cooked food 13 pass through the catalyst body 7 installed at the exhaust gas outlet 9 together with the exhaust gas generated from the gas burner 11, and the hydrocarbons are purified.

Effects of the Invention The effects of the catalyst body of the present invention are as follows: (i) Since it is a catalyst body in which fine powder is attached, even if the perovskite fine powder supported on the surface is detached, the background color remains the same. Therefore, it is aesthetically unsightly and is especially suitable for use in household combustors.

(ii) Since the catalyst body of the present invention forms transition metal oxides inside the pores of the catalyst carrier and causes blackening, the catalytic performance is greatly increased compared to a catalyst body using a catalyst carrier that does not blacken. can be done.

[Brief explanation of the drawing]

FIG. 1 is a longitudinal sectional view of a catalyst body according to an embodiment of the present invention, and FIG. 2 is a longitudinal sectional view of the catalyst body applied to a cooking appliance. DESCRIPTION OF SYMBOLS 1... Catalyst carrier, 2... Micropore, 3... Transition metal oxide fine particles, 5... Perovskite composite oxide, 6... Alumina.

Claims (1)

[Scope of Claims] 1. A catalyst body for exhaust gas purification installed in a combustion device, which includes a honeycomb structure made of a heat-resistant ceramic material having micropores inside, and a honeycomb structure made of a heat-resistant ceramic material having micropores inside the honeycomb structure. Supported transition metal oxide fine particles that exhibit a black color when fired in air;
Fine particles of perovskite composite oxide having oxidizing activity supported on the outer surface of the honeycomb structure, and fine particles of transition metal oxide and fine particles of perovskite composite oxide having adhesive properties by firing are combined into the honeycomb structure. and a supporting agent supported on the catalyst. 2. The catalyst body according to claim 1, wherein the honeycomb structure made of a heat-resistant ceramic material is made of any one of cordierite, α and γ alumina, mullite-zircon, and aluminum titanate.