JPH082411B2 - Deodorization method - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION <Field of Industrial Application> The present invention relates to a deodorizing method for removing odorous components causing an offensive odor by ozone.

<Prior Art> Odorous components contained in gas include ammonia, trimethylamine, hydrogen sulfide, methyl mercaptan, methyl sulfide, methyl disulfide, acetaldehyde, styrene, methyl ethyl ketone, acrolein, propionaldehyde, butyl alcohol, phenol, cresol. , Diphenyl ether, acetic acid, propionic acid, valeric acid, methylamine, dimethylamine, skatole, dimethylthioether, dimethylmercaptan, hydrogen chloride and allyl chloride. These odorous components are usually produced in human waste treatment plants,
It is discharged from sewage treatment plants, garbage incineration plants, various chemical industries, printing industries, plating industries, etc. and causes offensive odors. Therefore, conventionally, various methods for removing these odorous components have been proposed.

As a conventional deodorizing method, an adsorption deodorizing method using a porous substance such as activated carbon or zeolite, a wet treatment deodorizing method using an oxidizing agent or a reducing agent, and an ozone decomposing deodorizing method using ozone are known.

<Problems to be Solved by the Invention> However, none of the conventional deodorizing methods is a satisfactory deodorizing method.

That is, in the adsorptive deodorization method, since the adsorbent exerts its adsorption capacity for a finite period of time, it requires treatment such as regeneration, and requires a great deal of labor and cost for maintenance of the deodorizing device.

In the wet treatment deodorization method, treatment of a chemical solution such as an oxidizing agent is complicated.

Although the ozone decomposition deodorization method does not have the above-mentioned problems, the odorous components are not sufficiently removed by oxidative decomposition, and residual ozone may cause respiratory disorders and the like.

The present invention has been made to eliminate the problems of the ozone decomposition deodorization method, and an object thereof is to provide a deodorization method that is excellent in the ability to decompose and remove odorous components by ozone, and in which unreacted ozone hardly remains. And

<Means for Solving the Problems> The deodorizing method of the present invention is a deodorizing method of oxidizing and decomposing odorous components with ozone in the presence of a catalyst contained in a honeycomb molded body, wherein the honeycomb molded body is a catalyst and an electrically conductive material. The material is molded by mixing the material with a molding material, the honeycomb molded body is heated to heat the catalyst, and the odorous components are oxidatively decomposed in the presence of the heated catalyst.

That is, in the present invention, when the oxidative decomposition of the odorous component is performed in the presence of a catalyst, the conductive material becomes a resistor and generates heat by energizing the honeycomb formed body containing the catalyst and the conductive material. Since the catalyst is heated by this, the oxidative decomposition of the odorous component is significantly promoted, and the activity of the catalyst is further increased by heating,
Surplus ozone can be decomposed promptly, and it is economical because it does not heat the gas containing odorous components.

The above-mentioned honeycomb molded body is obtained by uniformly mixing the catalyst, the conductive material and the molding material, and then extruding into a honeycomb shape, or by molding only the molding material into a honeycomb shape and then immersing the catalyst and the conductive material. It is manufactured by adhering it by the like. Although the molded body can be used as it is,
Further firing can carbonize the molding material to further improve the conductivity.

Examples of the conductive material include graphite, carbon fiber, silicon carbide, silver, nickel chrome alloy, chrome aluminum alloy, and stainless steel.
These conductive materials can be used in various shapes such as powder, whiskers and short fibers. Examples of the molding material include methyl cellulose, polyvinyl chloride, polyethylene, polyamide and polyester. In addition, a plastic material such as clay may be added to the molding material in order to improve the extrudability.

The conductive material content in the honeycomb molded body is approximately 22 to 70.
% Is preferable, and if the content is less than this,
Sufficient heat generation cannot be obtained, and if it is more than this, contact between ozone and odorous components on the catalyst surface may be hindered.

FIG. 1 shows an example of a honeycomb formed body 7, in which a large number of square through holes 8 are formed along the flow direction of the odorous component-containing gas (indicated by an arrow), and this is formed into a casing. Install inside to get a deodorizer. Electrodes 9,9 (copper plate, stainless steel plate, etc. having a thickness of about 0.1 mm) are closely attached to both end surfaces of the molded body 7, and the conductive wires 10, 9 are connected to these electrodes 9, 9.
10 is connected so that the honeycomb molded body 7 can be energized.

The shape of the through-hole 8 of the honeycomb formed body 7 may be a quadrangle, or an arbitrary shape such as a hexagon or a triangle.
Further, as shown in FIG. 2, it is suitable that the honeycomb molded body 7 has a wall thickness t of about 0.1 to 7 mm and a pitch p of about 1 to 7 mm.

As the catalyst contained in the honeycomb formed body, for example, Mn
O _2, CuO, a combination _{Fe 2 O 3, TiO 2,} Ag 2 O, NiO, Co 3 O 4, Pt, one or more, such as Pd, MnO ₂ - alkali metal and / or alkaline earth Examples thereof include metal oxides and zeolite catalysts carrying metals having an enthalpy of oxide formation of 100 kcal / g or less oxygen atoms.

More preferable catalyst components include Cu, Mu, Co, Fe and N.
Examples of the catalyst include a combination of an oxide of at least one metal selected from the group consisting of i and at least one selected from the group consisting of TiO ₂ , Ag ₂ O and Au. _{Specifically, MnO 2 -TiO 2, CuO-} TiO 2, Co 3 O 4 -TiO 2, Fe 2 O 3 -Au
Binary catalyst such _{as, MnO 2 -Co 3 O 4 -TiO} 2, MnO 2 -Co 3 O 4 -Ag 2
O, such as a three-way catalyst, such as NiO-MnO ₂ -TiO _2, and the like.

As other preferable catalysts, clay and manganese dioxide, clay and manganese dioxide and titanium dioxide, or a part of manganese dioxide in Cu, Co,
Examples thereof include those substituted with an oxide of at least one metal selected from the group consisting of Fe, Ni and Ag. Specifically, MnO ₂ -CuO ₂ - clay, MnO ₂ -CuO ₂ - clay -TiO _2, Mn
O ₂ -Co ₃ O ₄ - clay, MnO ₂ -Co ₃ O ₄ - clay -TiO _2, MnO ₂ -
Fe ₂ O ₃ - clay, MnO ₂ -Fe ₂ O ₃ - clay -TiO _2, MnO ₂ -NiO
- clay, MnO ₂ -NiO- clay -TiO _2, MnO ₂ -Ag ₂ O-clay, such as MnO ₂ -Ag ₂ O-clay -TiO ₂ are exemplified. Here, the clay is a layered clay mineral such as pyrophyllite, talc, mica, chlorite, montmorillonite, kaolin, and halloysite, and specific examples thereof include kibushi clay and leech eye clay.

The content rate of the catalyst in the honeycomb formed body is appropriately determined depending on the type of catalyst used and the type of molding material,
Generally, about 30 to 76% is suitable.

Further, the heat generation temperature of the honeycomb formed body is 30 ° C. or higher, preferably 40 ° C. or higher, especially 50 ° C. or higher. When the catalyst temperature is lower than 30 ° C, ozone reacts with the catalyst, the generated high valent oxide is not decomposed, and oxygen accumulates in the catalyst, so the decomposition rate of odorous components of the catalyst gradually decreases. Therefore, it is not preferable.

The temperature at which the reaction rate does not decrease is determined by the amount of ozone loaded on the catalytically active component and the unit catalyst amount (the amount of ozone per unit time). As an amount representing these, the present inventors have found that the area velocity [AV, area verocity m ³ / m ² · Hr
… The reaction amount (Nm ³ / Hr) divided by the gas contact area (m ² / m ³ ) per unit volume of the catalyst] and the inlet ozone concentration (p
pm) and the product (hereinafter referred to as CA). For example
When CA is 100000, 60 ° C. in MnO ₂ catalyst, MnO ₂ -Ag ₂ O catalyst (MnO ₂ 80 wt%, Ag ₂ O20 _{wt%), MnO 2 -Ag 2 O} -TiO 2 catalyst (MnO ₂ 70 wt% , Ag ₂ O 10% by weight, TiO ₂ 20% by weight)
40 ° C. Further, when CA is 1000, the temperatures are 55 ° C., 50 ° C., and 35 ° C. for the above catalysts, respectively.

Further, the decomposition rate of the odorous component is determined by AV under the same temperature and the same ozone concentration condition, but it changes depending on the size of the pores of the used honeycomb molded body and the state of containing the catalyst.

The ozone coexisting with the catalyst during deodorization is appropriately determined depending on the type and concentration of the odorous component, the reaction temperature, the type and amount of the catalyst, and the like. For example, in the case of gas containing H ₂ S as odorous component preferably coexist H ₂ S1 mol ozone 1-2 moles, of ammonia per mole of ozone 3 mol in the case of gas containing ammonia It is preferable to coexist. Further, in the case of a gas containing methyl mercaptan, 1 to 1 ozone per mol of methyl mercaptan
It is preferable to coexist 4 mol.

When the concentration of the odorous component contained in the gas is high, ozone may coexist beyond the above range in order to improve the removal rate. In this case, since the excess ozone is decomposed by the catalyst, it is possible to prevent the ozone from being discharged from the deodorizer. However, if the amount of ozone is extremely excessive, excess ozone may remain in the gas after the deodorization process, so it is preferable to control the amount of ozone supplied to the deodorizer.

<Example> Next, the deodorizing method of the present invention will be described in detail with reference to Examples. However, the present invention is not limited to these examples.

Example 1 MnO ₂ —Ag ₂ O— having a specific surface area of 32 m ² / g and an average particle size of 30 μm
TiO ₂ (70% by weight MnO _2, 10% by weight Ag ₂ O, 20% by weight TiO ₂ )
After thoroughly kneading 2 kg, graphite powder (conductive material manufactured by Wako Pure Chemical Industries, Ltd.) 600 g, Hi metrolose (methyl cellulose, trade name manufactured by Shin-Etsu Chemical Co., Ltd.), and water, the pitch was 1.3. Extrusion was carried out by an extruder equipped with a honeycomb forming die having a wall thickness of 0.2 mm and a wall thickness of 0.2 mm. The obtained molded product was dried by ventilation, dried at 100 ° C. for 18 hours, and calcined at 450 ° C. for 3 hours. The honeycomb formed body was cut into a length of 30 mm and a width of 30 mm, copper electrodes were attached to both side surfaces as shown in FIG. 7, and the resistance was measured and found to be 314 Ω.

 This was mounted in a casing to obtain a deodorizer.

Test Example A deodorization test was performed using the deodorizer obtained in Experimental Example 1. That is, as shown in FIG. 3, while introducing the odorous component-containing gas into the deodorizer 12, ozone is introduced into the deodorizer 12 from the ozone generator 11 to cause the oxidative decomposition reaction of the odorous component. Part of the description after the deodorization was introduced to the ozone analyzer 13 and the odorous component analyzer 14, respectively, and the residual ozone amount and the residual odorous component amount were quantified. Here, the odorous component analyzer 14 is a gas chromatograph (for H ₂ S or methylamine analysis) 2
A group and one NH ₃ meter.

 The reaction conditions of ozone and odorous components are as follows.

Space velocity: 20000 / Hr Catalyst temperature: 50 ℃ at room temperature Odorous components: H ₂ S, NH ₃ or methyl mercaptan The test results are shown in the following table.

As is clear from the table, the deodorizer obtained in Example 1 has a high odorous component removal rate.

 Further, the ozone residual rate also shows a low value.

Therefore, it can be seen that, as in Example 1, by heating the catalyst, the effect of removing odorous components is improved and the residual amount of ozone can be reduced.

<Effects of the Invention> According to the present invention, a honeycomb formed body containing a catalyst and a conductive material is energized to heat the conductive material to heat the catalyst, and in the presence of the heated catalyst. Since the odorous components are oxidatively decomposed, the removal rate of the odorous components can be increased, the residual rate of ozone can be reduced, and the catalyst is heated without heating the gas containing the odorous components, which is economical. There is an effect that there is.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a perspective view showing a honeycomb formed body according to the present invention, FIG. 2 is a partially enlarged view thereof, and FIG. 3 is a flow sheet of a test device for examining the odorous component removing performance. 7: Honeycomb molded body, 9: Electrode, 10: Conductive wire

 ─────────────────────────────────────────────────── ─── Continuation of front page (56) Reference JP-A-55-54024 (JP, A) JP-A-53-22890 (JP, A) JP-A-53-22889 (JP, A) JP-A-63- 305923 (JP, A) JP-A-2-251226 (JP, A) Actually opened 50-10906 (JP, U) Actually opened 55-155523 (JP, U)

Claims (1)

[Claims] 1. A deodorizing method in which an odorous component is oxidatively decomposed by ozone in the presence of a catalyst contained in a honeycomb formed body, wherein the honeycomb formed body is formed by mixing a catalyst and a conductive material with a forming material. A deodorizing method, characterized in that the honeycomb molded body is heated to heat the catalyst, and the odorous components are oxidatively decomposed in the presence of the heated catalyst.