JPH02307510A - Ozone decomposer - Google Patents

Abstract

PURPOSE:To efficiently decompose ozone by sticking both a catalyst for decomposing ozone and a conductive material on an air-permeable base material to form a catalytic layer and fitting this catalytic layer to the inside of a casing. CONSTITUTION:An ozone decomposer is formed by parallel providing a plurality of catalytic layers 2 at a certain interval along the direction of flow of exhaust gas contg. ozone to the inside of a cylindrical casing 1. Exhaust gas is forcedly passed vertically for the surfaces of the respective catalytic layers 2. The electrodes 5 are fitted to both ends of the main body 4 of an air-permeable base material 3 and the conductors 6 are connected thereto. The amount of a catalyst carried on the base material is regulated to about 50-250%. Graphite, carbon fiber and silicon carbide, etc., are utilized as the conductive material. The heat evolution temp. of the heating base material is regulated to about 30 deg.C or more preferably about 50 deg.C or more. Thereby the decomposition efficiency of ozone can be enhanced.

Description

DETAILED DESCRIPTION OF THE INVENTION <Industrial Application Field> The present invention relates to an ozone decomposer for decomposing ozone contained in gas or the like.

<Prior art> Ozone contained in gas emits an unpleasant odor and has a negative impact on health by irritating the mucous membranes of the throat and lungs, so it is necessary to remove it from an environmental hygiene perspective. It is being

Conventionally, methods for removing ozone include adsorption methods using porous substances such as activated carbon and zeolite, and oxidative decomposition methods using catalysts such as Mn02.

<Problems to be Solved by the Invention> However, none of the conventional ozone removal methods was satisfactory.

That is, in the case of the adsorption method, it is necessary to regenerate, replace, etc. each time the adsorbent becomes saturated, and a great deal of labor and cost is required for maintenance.

In addition, although the oxidative decomposition method does not have the same problems as the adsorption method, the ozone decomposition catalysts used in the past may not be able to oxidize or decompose ozone sufficiently or under high load conditions (high concentration, There was a problem that the catalyst deteriorated at high SV).

In order to solve these problems, it is possible to raise the temperature of the ozone-containing exhaust gas, but this is not practical because the cost of raising the temperature increases.

The present invention was made in view of the above circumstances, and provides an economical ozone decomposer that can oxidize and decompose ozone at a high reaction rate even under high load conditions (high concentration, high SV). The purpose is to provide.

Means for Solving the Problems> The ozone decomposer of the present invention has a catalyst layer in which an ozone decomposition catalyst and a conductive material are attached to a breathable base material installed in a casing, and a conductive layer is attached to both ends of the catalyst layer. It is made by connecting lines.

That is, in the present invention, by applying electricity from a conductive wire to a breathable base material to which an ozone decomposition catalyst and a conductive material are attached, the conductive material becomes a resistor and generates heat, thereby reducing the temperature of the breathable base material. This technology takes advantage of the heating of a catalyst supported on the catalyst.Heating the catalyst efficiently decomposes ozone on the catalyst surface, preventing deterioration of the catalyst even under high load conditions, and providing long-term use. The effect can be sustained. Moreover, it is economical because it does not raise the temperature of the gas itself.

Examples of the breathable base material used in the present invention include woven fabrics made from organic fibers such as polyester, silica fibers, glass fibers, etc., and nonwoven fabrics such as polyester m fibers, ceramic fibers, and carbon fibers. These base materials have a temperature of 100°C or higher, preferably 150°C
It is preferable that the material has heat resistance of ℃ or more. Further, it is preferable that the material has excellent mechanical workability such as bending so that it can be used in any shape such as a wave shape or a bellows shape.

Furthermore, this material must have an excellent ability to support catalysts and conductive materials.

In addition, the air permeability of the base material is important from the viewpoint of reactivity and pressure loss.
It is preferable that the fl 4-s s porosity is 85% or more. When the air permeability is smaller than the above range, the reactivity increases, but pressure loss also increases, which is not preferable. On the other hand, if the air permeability is excessively high, there will be no pressure loss, but the reactivity will tend to decrease.

The catalyst used is a catalyst that is conventionally known as having an ability to decompose ozone, such as M n O2,
Cu Os F ez O3, A g 20% N
10, one or two of Co304, Pt, Pd, etc.
In addition, Mn02-TiO2, Mn02-alkali metal and/or alkaline earth metal oxides, which the present inventors have already applied for, and metals with an oxide formation enthalpy of 100 kcal/g oxygen atom or less. Examples include supported zeolite catalysts.

Here, the amount of catalyst supported on the base material is preferably about 50 to 250%. When the loading rate is higher than this range, there is no commensurate improvement in ozone decomposition efficiency, which is economically disadvantageous, and when the loading rate is lower than this range, a sufficient nitrogen oxide removal effect cannot be obtained. do not have.

Examples of the conductive material include graphite, carbon fiber, silicon carbide, silver, nickel-chromium alloy, chromium-aluminum alloy, stainless steel, and the like. The shape of the conductive material is not particularly limited, and various shapes such as powder, whisker shape, and short fibers can be used.

The amount of the conductive material deposited is preferably about 20 to 60%; if the amount is less than this, conductivity cannot be obtained and sufficient heat generation cannot be obtained. Contact between the catalyst and ozone may be inhibited.

Examples of methods for attaching the catalyst and conductive material include a method in which the base material is immersed in a slurry containing these components, and when a nonwoven fabric base material is used, a method in which the above components are incorporated during papermaking. can be given.

FIG. 1 shows an example of the ozone decomposer of the present invention.

The ozone decomposer shown in Fig. 1 has a plurality of catalyst layers 2 arranged in parallel at regular intervals along the flow direction (indicated by arrows) of exhaust gas containing ozone in a cylindrical casing 1. It is forced to pass perpendicularly to the surface of each catalyst layer 2.

FIG. 2 is a plan view showing the air-permeable base material 3 used in FIG. 1, and in this figure, electrodes 5 are attached to both ends of the main body 4, to which conductive wires 6 are connected.

FIG. 3 is similar to the ozone decomposer shown in FIG. 1, except that a corrugated catalyst layer 2' is used to increase the efficiency of contact with exhaust gas.

FIG. 4 is a plan view showing the breathable base material 8 used in FIG. 3, and in the figure, electrodes 5 are attached to both ends of the main body 70, and conductive wires 6 are connected to these.

In FIG. 5, catalyst layers 11 are arranged side by side at regular intervals in a direction perpendicular to the flow direction of exhaust gas indicated by arrows, and exhaust gas is forced to pass through parallel to the surface of each catalyst layer 11.

The catalyst layer 11 used here can be the same as the catalyst layer 2 shown in FIG.

Further, FIG. 6 shows one catalyst layer 9 folded into a bellows shape and housed in a frame-shaped casing 10, and the arrow indicates the flow direction of the ozone-containing exhaust gas. In the catalyst layer 9, filters are superimposed on one or both sides of a heat generating base material in the same manner as described above.

Moreover, electrodes (not shown) are attached to both ends of the heat generating base material, and lead wires are connected to these electrodes so that the heat generating base material generates heat. The casing 10 equipped with the catalyst layer 9 may be attached as it is to an ozone exhaust port (not shown), or a plurality of casings 10 may be arranged in parallel so that the exhaust gas sequentially passes through the ozone layer.

The exothermic temperature of the exothermic substrate supporting the catalyst is suitably 30°C or higher, preferably 40°C or higher, and more preferably 50°C or higher. When the catalyst temperature is below 30℃, ozone reacts with the catalyst and the high valence oxides produced are not decomposed.
Since oxygen accumulates in the catalyst, the decomposition cycle rate gradually decreases, resulting in a decrease in the decomposition reaction rate (decomposition activity), which is undesirable.

Further, the temperature at which the rate of these reactions does not decrease is determined by the catalyst active component and the amount of ozone applied to a unit amount of catalyst (the amount of ozone per unit time).

As a quantity expressing these, the present inventors used areal velocity (AV
Sarea velocity m'4IIHr・
...It is the value obtained by dividing the reaction amount (N m' / H) by the gas contact area per unit volume of catalyst (r + t'4?)
and the inlet ozone concentration (ppm) (hereinafter referred to as CA). For example, when CA is toooooo,
For Mn02 catalyst, it is 60 °C and MnOz-Ag
20 catalyst (Mn0280wt%, Agz020wt%
) at 55°C, MnOz-Ag20-T i 02 catalyst (Mn0270 wt%, Agz010 wt%, Ti0z
20% by weight), the temperature is 40°C. Also, CA is 1000
55°C, 50°C and 3°C for each of the above catalysts, respectively.
The temperature is 5°C.

Further, the ozone decomposition rate is defined by AV under the same temperature and ozone concentration conditions, but it changes depending on the pore size of the base material used, the state of catalyst support in the catalyst layer, etc.

<Example> Next, the ozone decomposer of the present invention will be described in detail by giving examples. However, the present invention is not limited only to these examples.

Example 1 Mn0 with a specific surface area of 32 m'/g and an average particle size of 50 μ
z -Agz 0-TiO2 (MnOz 80% by weight,
Thoroughly mix 50 g of 5i02 sol (Snowtex O manufactured by Nissan Chemical ■), 50 g of graphite powder (conductive material manufactured by Wako Pure Chemical Industries, Ltd.), and water. concentration 100 g/
A slurry of N was prepared. Glass cloth (manufactured by Unitika M Glass Co., Ltd., Ls s F t 10) was added to this slurry.
0 (1, Air permeability 3014/81 Dimensions 30ssX 35m
m) was immersed, pulled up, and then dried with hot air using a dryer to obtain a catalyst layer. At this time, the loading rate was 146%. Next, copper electrodes were attached to the 5th side of 35m. The resistance of the obtained catalyst layer was 210Ω.

These were arranged side by side in the casing 1 in 1 to 7 layers as shown in FIG. At this time, the glass cloth was placed in front of the wire mesh with respect to the gas flow direction. 1
The length up to 7 layers was 70+am. The gas contact area per single volume of this ozone decomposer was 100 m'4.

Example 2 Ceramic fiber vapor (manufactured by Oriental Asbestos Co., Ltd., basis weight 90 g) was added to the same slurry as used in Example 1.
An ozone decomposer was obtained in the same manner as in Example 1, except that a catalyst layer having a thickness of 5 mm and dimensions of 30 mm x 351 mm was immersed and dried with hot air using a dryer to obtain a catalyst layer with a support rate of 125%. Here, the resistance of the obtained catalyst layer was 193Ω.

Ozone decomposition test An ozone decomposition test was conducted using each of the ozone decomposers obtained in Examples 1 and 2. That is, air is passed through an ozone generator to contain ozone at a predetermined concentration, then introduced into an ozone decomposer, and the ozone concentration in the air that has passed through the ozone decomposer is measured with an ozone analyzer. The ozone decomposition rate was determined.

The results are shown in the table below.

(CI - C2)/C+
- Ozone concentration at the outlet of the ozone decomposer At this time, an electric current was passed through the catalyst layer in the ozone decomposer to heat it to the temperature shown in the following table. Other reaction conditions and ozone decomposition rates are also shown in the table below. Note that the temperature of the catalyst layer and the gas outlet temperature were each measured using a resistance temperature detector.

In addition, in the table, the outlet 1 population for the gas outlet temperature and inlet ozone concentration is the outlet of the ozone decomposer.

Each signifies an entrance.

(Left space below) From the table, it can be seen that the higher the temperature of the catalyst layer by energizing it, the higher the ozone decomposition rate, and the effect lasts for a long time.

<Effects of the Invention> As described above, in the present invention, by supplying electricity from a conductive wire to a breathable base material to which an ozone decomposition catalyst and a conductive material are attached, the catalyst becomes a heating element and is heated. Ozone decomposition on the catalyst surface is efficiently carried out, the deterioration of the catalyst is prevented even under high load conditions, and the effect can be sustained over a long period of time. Moreover, it is economical because it does not raise the temperature of the gas itself.

[Brief explanation of the drawing]

FIG. 1 is a schematic cross-sectional view showing an example of the ozone decomposer of the present invention, FIG. 2 is a plan view showing an example of the heat generating base material, and FIG. 3 is a schematic cross-sectional view showing another example of the ozone decomposer of the present invention. 4 is a schematic perspective view showing a heat generating base material used in the ozone decomposer of FIG. 3, and FIGS. 5 and 6 are schematic perspective views showing still other examples of the ozone decomposer of the present invention, respectively. It is.

Claims (1)

[Claims] 1. An ozone decomposer characterized in that a catalyst layer in which an ozone decomposition catalyst and a conductive material are attached to a breathable base material is installed in a casing, and conductive wires are connected to both ends of the catalyst layer.