JPH04265123A - Method for decomposing malodorous component by catalytic oxidation - Google Patents

Abstract

PURPOSE:To deodorize fluid contg. a malodorous component such as gas contg. lower fatty acid by decomposition with ozone without causing the deterioration of a catalyst due to the accumulation of the lower fatty acid on the catalyst, even when the gas is subjects to deodorization treatment especially under circulation. CONSTITUTION:When a malodorous component is decomposed by catalytic oxidation on a catalyst with ozone, a filter for adsorbing or absorbing lower fatty acid is fitted to the latter part of the catalyst or such filters are fitted to the former and latter parts.

Description

[Detailed description of the invention]

0001

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for catalytic oxidative decomposition of odor-producing components (hereinafter referred to as odorous components) contained in gases and the like.

0002

[Prior Art] Conventionally, methods for removing odorous components contained in gases, etc. include an adsorption deodorization method using porous materials such as activated carbon and zeolite, a wet treatment deodorization method using an oxidizing agent or a reducing agent, and a catalyst. Various methods are known, such as an ozonolysis deodorization method that decomposes and deodorizes odorous components using ozone in the presence of ozone.

However, none of these conventional deodorizing methods is satisfactory. That is, according to the adsorption deodorization method,
Generally, due to the limited adsorption capacity of adsorbents,
It requires a lot of effort and expense to maintain and manage the device. The wet process deodorizing method requires post-treatment of the oxidizing agent chemical solution, which is complicated. Although the ozonolysis deodorization method does not have the above-mentioned problems, the oxidative decomposition of odorous components has traditionally been limited, and it has not yet reached a level that is satisfactory for practical use. From a sanitary standpoint, there are problems such as the need to decompose ozone contained in the gas after deodorizing treatment.

0004

[Problems to be Solved by the Invention] In order to solve the above-mentioned problems in the conventional ozone decomposition and deodorization method, the present inventors have already developed a method that has a superior ability to decompose and deodorize odorous components compared to the conventional method. At the same time, various ozone decomposition deodorization methods have been proposed in which almost no unreacted ozone remains after deodorization treatment.

However, in general, deodorizing treatment of fluids containing odorous components, especially gases from the living environment, is often carried out by circulating and supplying the gas to a reactor filled with a catalyst. Gases in such living environments often contain trace amounts of lower fatty acids, and in this case, the present inventors
It has been found that even in the above-mentioned method, the lower fatty acids are generally not susceptible to oxidative decomposition by the catalyst, and are accumulated in the catalyst or released from the processing equipment, and react with the catalyst components, leading to the deterioration of the catalyst. Ta.

The present invention was made in order to solve this new problem, and even if the gas containing lower fatty acids is deodorized (especially while being circulated), such lower fatty acids will not be present in the catalyst. An object of the present invention is to provide an ozonolysis deodorization method for a fluid containing odorous components, in which the catalyst does not deteriorate because no odor components are accumulated.

[0007]

[Means for Solving the Problems] The present invention provides a method for catalytically oxidizing decomposition of odorous components on a catalyst using ozone.
It is characterized by installing a lower fatty acid adsorption or absorption filter after the catalyst, or before and after the catalyst. In the present invention, odorous components are not particularly limited, but typical examples include ammonia, methylamine, dimethylamine, trimethylamine, hydrogen sulfide, methyl mercaptan, dimethyl mercaptan, methyl sulfide, Methyl sulfide, acetaldehyde, styrene,
Examples include methyl ethyl ketone, acrolein, propionaldehyde, butyl alcohol, phenol, cresol, diphenyl ether, acetic acid, propionic acid, valeric acid, skatole, dimethyl thioether, hydrogen chloride, alkali chloride, and the like.

[0008] In the present invention, lower fatty acids include formic acid, acetic acid, propionic acid, butyric acid, n-valeric acid, isovaleric acid, and the like. All of these are formed when microorganisms decompose hydrocarbons emitted from the sweat and other secretions of humans and animals in the living environment, and are used for the purpose of deodorizing. It is often mixed into gases containing odorous components, and is sometimes included as an odorous component from the beginning.

According to the method of the present invention, when gases containing such lower fatty acids in addition to or as an odorous component are oxidatively decomposed by a catalyst, Filters for adsorbing or absorbing lower fatty acids as described above are installed in the front and rear stages. Such filters can be used as adsorbents or absorbents themselves or in the form of honeycombs, pellets, sheets, fibers, foams, etc. together with an inert carrier material such as clay. . As the adsorbent or absorbent, for example, adsorbents such as various zeolites, alumina, activated carbon, etc., and combinations of these adsorbents with oxides, hydroxides, and carbonates of alkali metals or alkaline earth metals are preferable. used.

[0010] As a specific example, for example (hereinafter, metal is
shall indicate its oxide, hydroxide or carbonate. )
, activated carbon-lithium, activated carbon-sodium, activated carbon-potassium, activated carbon-barium, activated carbon-magnesium, activated carbon-calcium, activated carbon-strontium, etc., activated carbon-calcium-sodium, activated carbon-calcium-potassium, activated carbon-calcium- Three-component systems such as lithium, activated carbon-strontium-potassium, and activated carbon-magnesium-potassium can be mentioned. Among these, the metal components include lithium, sodium,
Potassium, magnesium, strontium, barium, etc. are preferred, and the first three are particularly preferred.

[0011] In such adsorbents or absorbents, the activated carbon usually ranges from 30 to 99.9% by weight, and the metal oxide, hydroxide or carbonate contains from 70 to 0.1% by weight. range. A filter containing such a component contains 30% by weight or more, preferably 50% by weight or more of the above-mentioned adsorbent or absorbent. The production of such filters is already well known in the technical field of various catalysts, and the filter used in the present invention can be used, for example, in the impregnation method, the kneading method, and the papermaking method in which sheets are formed with various fibers by the papermaking method. It is prepared as appropriate by methods such as methods. It goes without saying that in the preparation of such filters, organic binders and molding aids can be used as necessary, and reinforcing materials such as inorganic fibers can be used to increase the mechanical strength of the resulting filter. do not have.

The conditions for treating gas with such a filter depend on the concentration of lower fatty acids in the gas, but since the lower fatty acids contained in the gas to be treated are usually trace amounts in the living environment, the space velocity ( SV) from 1,000 to 1,000,000
(1/hr). Next, in the method of the present invention, the catalyst for oxidatively decomposing the odorous components includes metals such as copper, manganese, cobalt, iron, nickel, titanium, silicon, aluminum, silver, platinum, etc. oxides are preferably used. These may be used alone or as a mixture or composite of two or more. More specifically, for example, monocatalysts such as manganese dioxide, manganese dioxide-activated carbon, manganese dioxide-titanium dioxide, copper oxide-titanium dioxide, cobalt oxide-titanium dioxide, ferric oxide-titanium dioxide, iron dioxide-gold binary catalysts such as manganese dioxide-cobalt oxide-titanium dioxide, manganese dioxide-activated carbon-alkali metal oxide,
Examples include hydroxides or carbonates, and three-way catalysts such as manganese dioxide-cobalt oxide-silver oxide, nickel oxide-manganese dioxide-titanium dioxide, and the like. However, in the method of the present invention, the catalyst used is not limited to these.

[0013] These catalysts are usually supported on a carrier,
It can be used as structures of various shapes, such as honeycomb molded bodies, pellet-shaped bodies, cylindrical bodies, plate-shaped bodies, pipe-shaped bodies, etc. When the catalyst is used as a structure in which the catalyst is supported on a carrier, the amount of the catalyst supported in the structure is generally preferably 50% by weight or more, particularly preferably 75% by weight or more. The production of such a catalyst structure is already well known in various catalyst technical fields, as is the case with the above-mentioned filter, and the catalyst structure used in the present invention can also be produced by, for example, an impregnation method, a kneading method, a combination method, etc. It is appropriately prepared by a method such as a precipitation method or an oxide mixing method. In the preparation of such a catalyst structure, an organic binder or a forming aid may be used, or a reinforcing material such as an inorganic fiber may be used to increase the mechanical strength of the resulting catalyst structure, if necessary. .

In the method of the present invention, when oxidatively decomposing odorous components in the presence of the above-mentioned catalyst, ozone can The amount to be used or the amount to coexist is appropriately selected depending on the type and amount of the catalyst used. For example, when the odorous component is hydrogen sulfide, it is preferable to use 1 to 2 moles of ozone per mole of hydrogen sulfide. When the odorous component is ammonia, it is preferred to use 1 to 3 moles of ozone per mole of ammonia. Furthermore, when the odorous component is methyl mercaptan, it is usually preferable to use 1 to 4 mol of ozone per 1 mol of methyl mercaptan. However, for example, if the concentration of odorous components in the gas for deodorization is high, there is no problem in using ozone in large amounts beyond the above range in order to increase the decomposition rate of the odorous components. do not have. On the other hand, it should be avoided to use too much ozone so that a large amount of surplus ozone remains in the gas after deodorizing treatment.

[0015] In the method of the present invention, the reaction temperature when bringing the gas containing an odorous component into contact with ozone in the presence of a catalyst is usually preferably in the range of 0 to 40°C, particularly in the range of 10 to 40°C.
A range of ~30°C is preferred. When the reaction temperature is lower than 0°C, the reaction rate tends to be too slow, and when it exceeds 40°C, there is no corresponding benefit, and in fact, it is difficult to increase the temperature of gases containing odorous components. The required energy costs make the process less economical.

Furthermore, contact between the catalyst and the gas containing the odorous component is preferably carried out at an areal velocity in the range of 5 to 50. Here, the areal velocity is a value obtained by dividing the reaction amount of gas containing an odorous component (N cubic meters/hour) by the gas contact area per unit volume of catalyst (square meter/cubic meter). When the area velocity is less than 5, an unnecessarily large amount of catalyst is required, while when it exceeds 50, the efficiency of decomposing odorous components is low and it is difficult to obtain satisfactory results.

The method of the present invention can be applied to waste discharged from, for example, but not limited to, human or animal living spaces, human waste treatment plants, garbage incineration plants, printing factories, plating factories, chemical factories, etc. Suitable for deodorizing exhaust gas.

[0018]

[Examples] The present invention will be explained below with reference to Examples.
The present invention is not limited in any way by these Examples. A. Preparation of catalyst Example 1 Manganese dioxide 704 with a specific surface area of 48 square meters/g
g as titania sol (titanium dioxide content 150g/l)
In addition to 1034ml, add 250g of glass beads.
was added and mixed with stirring for 30 minutes to obtain a slurry. This slurry was impregnated into a corrugated honeycomb made of ceramic fibers with a porosity of 81% and a pitch of 4.0 mm.
A honeycomb structure was prepared as a binary catalyst in which manganese dioxide/titanium dioxide (molar ratio 82/18) was supported at a loading rate of 95%. B. Example 1 of Preparation of Lower Fatty Acid Filter Kibushi clay was dried at 100° C. for 18 hours, and then ground in a sample mill with a screen opening of 0.5 mm. Similarly, activated carbon (strong "Shirasagi" (registered trademark) manufactured by Takeda Pharmaceutical Co., Ltd.) was pulverized using a sample mill with a screen opening of 0.5 mm.

After pulverizing and mixing 20 kg of the above-mentioned pulverized clay and 20 kg of pulverized activated carbon in a V-blender, a methylcellulose-based organic binder (Yuken Industries Co., Ltd.) was added to the mixture.
B-32) 2 kg and water were added and sufficiently kneaded in a kneader to prepare clay. This clay was put into an auger screw type extruder equipped with a die for honeycomb extrusion, and extruded into a honeycomb-shaped article. In this extrusion molding, the moisture content of the clay was adjusted so that the extrusion pressure was 30 to 35 kg/cm2.

[0020] Next, this honeycomb-like material was dried with ventilation at room temperature, and then heated at a heating rate of 5°C/hour in a nitrogen atmosphere for 40 minutes.
After raising the temperature to 0°C, it was held at that temperature for 3 hours. After that, it was cooled at a temperature decreasing rate of 10°C/hour, and the opening ratio was 55%.
A honeycomb molded body with a pitch of 1.8 mm was obtained. The water absorption rate of this honeycomb molded body was 23%. Example 2 A part of the honeycomb molded body obtained in Example 1 was cut out,
After immersing in a 300 g/l potassium hydroxide aqueous solution and removing excess moisture, it was dried with ventilation at 120°C for 3 hours to obtain a two-component system of activated carbon/potassium hydroxide (weight ratio 93.5/6.5). A honeycomb structure was fabricated as a lower fatty acid filter. Example 3 In Example 2, instead of the potassium hydroxide aqueous solution, 3
Except for using 00 g/l sodium hydroxide aqueous solution,
In the same manner as in Example 1, a binary lower fatty acid filter of activated carbon/sodium hydroxide (weight ratio 93.5/6.5) was produced. Example 4 In Example 2, instead of the potassium hydroxide aqueous solution, 3
A two-component activated carbon/lithium hydroxide (weight ratio 93.5/6.5) lower fatty acid filter was produced in the same manner as in Example 1, except that a 00 g/l lithium hydroxide aqueous solution was used. Example 5 In Example 1, in the process of producing a honeycomb formed body, 20 kg of activated carbon and 2.22 kg of magnesium carbonate were added.
Activated carbon/
A two-component lower fatty acid filter of magnesium carbonate (90/10 weight ratio) was prepared. Example 6 In Example 1, in the process of producing a honeycomb formed body, 20 Kg of activated carbon and 2.22 Kg of calcium carbonate were added.
A two-component lower fatty acid filter of activated carbon/calcium carbonate (weight ratio 90/10) was produced in the same manner as in Example 1, except that g was used. Example 7 In Example 1, in the process of producing a honeycomb formed body, 20 kg of activated carbon and 2.2 kg of strontium carbonate were added.
A two-component lower fatty acid filter of activated carbon/strontium carbonate (weight ratio 90/10) was produced in the same manner as in Example 1, except that 2 kg was used. Example 8 In Example 1, in the process of producing a honeycomb formed body, 20 kg of activated carbon and 2.22 kg of barium carbonate were used.
A two-component lower fatty acid filter of activated carbon/barium carbonate (weight ratio 90/10) was produced in the same manner as in Example 1, except that . Example 9 The honeycomb molded body obtained in Example 6 was treated with potassium hydroxide in the same manner as in Example 2 to form activated carbon/calcium carbonate/
A three-component lower fatty acid filter of potassium hydroxide (weight ratio 84/9.5/6.5) was prepared. Example 10 The honeycomb molded body obtained in Example 6 was treated with sodium hydroxide in the same manner as in Example 2, and the three components of activated carbon/calcium carbonate/sodium hydroxide (weight ratio 84/9.5/6.5) were prepared. A lower fatty acid filter was created. C. Catalytic activity test Using each of the lower fatty acid filters and catalysts obtained in Comparative Examples 1 to 10 above, a catalytic activity test was carried out under the following reaction conditions using a test equipment configuration as shown in the flow sheet of Figure 1. I did it. Reaction conditions Space velocity: 20000/hour Reaction temperature
: 20℃ Inlet ozone concentration: 10 ppm Odorous components: Methyl mercaptan: 5 ppm Propionic acid: 1 ppm Under these conditions, a lower fatty acid filter was installed at the rear stage of the catalytic reactor, and ozone decomposition was performed at the initial stage and after 100 hours. The degree of deterioration of the catalyst was investigated by measuring the decomposition rate and odor component decomposition rate. Example 1
-1, 2-1 and 3-1, lower fatty acid filters were installed in the front and rear stages of the catalytic reactor.

Catalytic activity was examined as follows. That is,
Air is introduced into an ozone generator 1 to contain a predetermined concentration of ozone, a gas containing odor components and lower fatty acids is mixed with the ozone-containing air, and this mixed gas is passed through a reactor 2 filled with a catalyst and a lower fatty acid filter. 3 (hereinafter, the assembly of the reactor and filter is referred to as a processing device), the gas is deodorized in the reactor, the lower fatty acids are removed by the filter, and a part of the deodorized gas is sent to the ozone analyzer. 4, residual ozone in the gas after the treatment was quantitatively analyzed to determine the ozone decomposition rate.In addition, the remaining gas after the deodorization treatment was led to a gas chromatograph 5 to determine the remaining ozone. The odorous components were quantitatively analyzed to determine the decomposition rate of the odorous components.

Here, the ozone decomposition rate and the odorous component decomposition rate are calculated from the respective concentrations at the inlet and outlet of the processing apparatus measured by an ozone analyzer and a gas chromatograph, respectively, using the following equations. Decomposition rate (%) = [(inlet concentration - outlet concentration)
/inlet concentration]×100 As a comparative example, a catalytic activity test was conducted in the same manner as above without installing a lower fatty acid filter in the catalytic reactor.

The above results are shown in Tables 1 and 2.

[0024]

[Table 1]

[0025]

[Table 2]

[0026]

Effects of the Invention As is clear from the results shown in Table 1, according to the method of the present invention, by installing a lower fatty acid absorption filter or an adsorption filter in the rear stage (and front stage) of the catalytic reactor, long-term It is possible to maintain high ozone decomposition rates and odor component decomposition rates over time.

[Brief explanation of the drawing]

FIG. 1 shows a flow sheet for conducting catalyst activity tests.

[Explanation of symbols]

1... Ozone generator, 2... Catalyst reactor, 3... Lower fatty acid filter, 4... Ozone analyzer, 5... Gas chromatograph.

Claims (2)

[Claims] Claim 1: A method for catalytically oxidizing decomposition of odoriferous components on a catalyst using ozone, characterized in that a lower fatty acid adsorption filter or absorption filter is installed after the catalyst, or before and after the catalyst. Method. 2. A method for catalytically oxidizing decomposition of the odorous components on the catalyst using ozone by circulating a fluid containing odorous components into a reactor filled with a catalyst, in which a downstream stage of the reactor,
Or a method for deodorizing a fluid, characterized by installing lower fatty acid adsorption or absorption filters in the front and rear stages.