JP3576189B2 - Odor removal method and odor component adsorbent - Google Patents

Description

[0001]
[Industrial applications]
The present invention relates to a method for efficiently removing malodorous components such as ammonia and amines in exhaust gas.
[0002]
[Prior art]
Since malodorous components such as ammonia and amines show a strong odor even in a very small amount (ppm or less), a method excellent in complete removal performance is required for the treatment of these components. And it must be economically superior. Examples of a method for treating exhaust gas containing a malodorous component include an adsorption method, a chemical cleaning method (absorption method), and a combustion method (direct combustion method, catalytic combustion method).
[0003]
In the case of treating a large amount of exhaust gas containing a small amount of offensive odor, cost becomes a problem particularly. Among the above methods, the adsorption method is advantageous in cost, but a more economical treatment method is desired. In the adsorption method, replacement of the adsorbent and post-treatment are problematic. In order to solve this problem, a method combining an adsorption method and a catalytic combustion method is promising. In this method, ordinary exhaust gas treatment is performed at normal temperature by an adsorption method. When the amount of the malodor component adsorbed on the adsorbent increases and the malodor removal performance decreases, the auxiliary combustion furnace is ignited to heat the combustion catalyst layer to the operating temperature. With the heat of the exhaust gas, the adsorbent is heated to desorb the adsorbed malodorous component, and the adsorbent is regenerated. At the same time, the desorbed malodorous component is sent to the combustion catalyst layer, where it is completely burned and removed. Depending on the concentration of the malodorous component, no auxiliary fuel is required at this time.
According to this method, since the adsorbent is repeatedly regenerated in the apparatus, long-term operation can be performed without troublesome and uneconomical replacement of the adsorbent, which is extremely advantageous in terms of cost. However, in order to realize this method, it is necessary to use an adsorbent that can withstand heat for repetitive regeneration (usually 350 to 450 ° C.) and reversibly adsorb and desorb a malodorous component.
[0004]
As an adsorbent having a large adsorption capacity and heat resistance, zeolite is promising. The present inventors have found that H-mordenite having an SiO ₂ / Al ₂ O ₃ molar ratio (hereinafter simply referred to as a silica / alumina ratio) of 10 to 50 is extremely excellent against basic odors such as ammonia and trimethylamine. Clarified capacity. However, H-mordenite does not readily desorb malodorous components because of its strong adsorption power to malodorous components, requires a higher temperature (500 ° C. or higher) treatment for regeneration, and has a large adsorption capacity for long-term use. May decrease gradually. Therefore, it is necessary to reduce only the adsorptive power without decreasing the adsorption capacity of H-mordenite and to reversibly adsorb and desorb the odor at a lower temperature.
[0005]
[Problems to be solved by the invention]
An object of the present invention is to propose a method of using an adsorbent having appropriate adsorption / desorption characteristics as a method capable of efficiently and inexpensively treating a large amount of exhaust gas containing a trace amount of malodor.
[0006]
[Means for Solving the Problems]
The above object of the present invention is achieved by the following configuration.
That is, in a method of removing malodorous components such as ammonia and amines in exhaust gas by adsorbing and concentrating the adsorbent, and then intermittently heating the adsorbent to burn and remove malodorous components desorbed from the adsorbent, copper A method of removing an odor using an adsorbent obtained by ion-exchanging H-mordenite having a silica / alumina ratio of 10 to 50 with one or more ions selected from manganese, cobalt and iron elements, or
A malodorous component adsorbent which is easy to adsorb and desorb malodorous components composed of components obtained by ion-exchanging H-mordenite having a silica / alumina ratio of 10 to 50 with one or more ions selected from copper, manganese, cobalt and iron. is there.
At this time, a catalyst for heating the adsorbent for desorbing the malodorous component adsorbed and concentrated on the adsorbent and a combustion catalyst for burning and removing the malodorous component desorbed from the adsorbent can be used.
According to the method of the present invention, the adsorbent can be regenerated at a lower temperature (350 ° C. or lower), which is extremely advantageous in terms of cost.
[0007]
The shape of the adsorbent used in the present invention is used in the form of granules, spheres, columns, honeycombs, plates, hollow columns, etc., depending on the case to be applied. Is selected so as to reduce.
In addition, when the adsorbent of the present invention supports a base metal component such as manganese, iron, copper, and cobalt, it helps to desorb malodorous substances and prevents coke precipitation. Further, it is desirable to support a small amount of a noble metal such as platinum or palladium, because it helps deodorization of odorous substances and also prevents coke precipitation.
As the combustion catalyst used in the present invention, a catalyst in which noble metals such as platinum, gold, silver and palladium and base metals such as manganese, iron, cobalt and copper are supported on alumina having a large specific surface area is used. Manganese, iron, cobalt, and copper are components that are added if necessary. Further, supporting an oxide such as lantana (La ₂ O ₃ ), barrier (BaO), ceria (CeO ₂ ) as a cocatalyst is effective for improving the ignitability and heat resistance of the catalyst.
[0008]
[Action]
Normally, at a temperature lower than 200 to 400 ° C., the catalytic action is insufficient, and at a temperature higher than 200 ° C., the generation of fuel NOx increases. Therefore, an adsorbent that completely desorbs malodorous components in this temperature range is desirable. The adsorbent used in the method for removing malodor of the present invention can burn and remove adsorbed malodor components such as ammonia and amines at 200 to 400 ° C. In addition, the zeolite used as the adsorbent of the present invention is an H-mordenite zeolite having a silica / alumina ratio of 10 to 50. This zeolite has heat resistance and an adsorption capacity for basic malodorous components such as ammonia and amines. It shows extremely excellent adsorption capacity even among zeolite-based substances having a large value.
An acidic hydroxyl group is present on the surface of H-mordenite, and this is a site for adsorbing the malodorous substance. When the silica / alumina ratio exceeds 50, the acidity of this site becomes stronger, but the number of sites becomes smaller, and the adsorption capacity decreases. Further, in this case, the offensive odor component is strongly adsorbed and is not easily desorbed. On the other hand, if the silica / alumina ratio is less than 10, the acidity of the site becomes insufficient, and the malodorous component cannot be sufficiently adsorbed. Thus, H-mordenite having a silica / alumina ratio of 10 to 50 has the highest adsorption capacity and is preferable, but still has a strong adsorption power for malodorous components, and requires a higher temperature (500 ° C. or higher) for complete regeneration. During long-term use, the adsorbing capacity may gradually decrease due to caulking or the like.
[0009]
Therefore, the present inventors have studied diligently to reduce only the adsorptive power without reducing the adsorption capacity of H-mordenite and reversibly adsorb and desorb the malodor at lower temperatures. It has been found that an adsorbent ion-exchanged with one or more ions selected from the elements of manganese, cobalt and iron is suitable for the adsorption / desorption system of the present invention. It is considered that the above-mentioned ions moderately weaken the acidity of H-mordenite, add a catalytic action, and decompose some offensive odor components to enhance desorption characteristics.
Further, as the combustion catalyst of the system of the present invention, a catalyst in which a noble metal-based catalyst in which platinum or palladium is supported on an alumina carrier and a base metal such as manganese, iron, cobalt, or copper is supported is usually used. It can burn off odor components such as ammonia and amines at 200 to 400 ° C.
[0010]
【Example】
An embodiment of the present invention will be described with reference to the drawings.
FIG. 1 shows the configuration of an apparatus using the adsorbent according to the present embodiment. The apparatus of FIG. 1 includes a heat exchanger 1, an auxiliary combustion furnace 2, and a combustion catalyst layer 3 integrated with an adsorbent layer. The exhaust gas containing the malodorous component is sent to the adsorbent layer in the heat exchanger 1, and the malodorous component is removed by adsorption. Before the odorous substances are concentrated on the adsorbent and the adsorption capacity reaches saturation, the auxiliary combustion furnace 2 is started and the temperature of the combustion catalyst layer 3 is raised to 200 to 350 ° C., and the exhaust heat is exchanged. To the adsorbent layer via the vessel 1. The malodorous substance desorbed from the adsorbent is burned and removed by the combustion catalyst layer 3, and the adsorbent is regenerated.
[0011]
Example 1
H-mordenite having a silica / alumina ratio of 23 (manufactured by Tosoh Corporation) was added to a 0.5N aqueous cobalt acetate solution, and the mixture was kept at 80 to 90 ° C. for 8 hours while stirring in an oil bath, followed by decantation. The supernatant was removed. By repeating this operation three times, ion exchange of H-mordenite was performed. Next, after washing with ion-exchanged water, drying was performed in a dryer at 120 ° C. for 8 hours, and drying at 500 ° C. for 2 hours to obtain cobalt ion-exchanged mordenite, which was used as an adsorbent.
Example 2
A copper ion-exchanged mordenite was obtained in the same manner as in Example 1 except that the aqueous solution of cobalt acetate was replaced with an aqueous solution of copper acetate, and used as an adsorbent.
Example 3
A manganese ion-exchange mordenite was obtained in the same manner as in Example 1 except that the aqueous solution of cobalt acetate was replaced with the aqueous solution of manganese nitrate.
Example 4
Iron ion mordenite was obtained in the same manner as in Example 1, except that the aqueous cobalt acetate solution was replaced with an aqueous iron nitrate solution, and used as an adsorbent.
Example 5
A cobalt ion exchange mordenite was obtained in the same manner as in Example 1 except that the H-mordenite of Example 1 was replaced with H-mordenite having a silica / alumina ratio of 13, and was used as an adsorbent.
Example 6
A cobalt ion exchange mordenite was obtained in the same manner as in Example 1 except that the H-mordenite in Example 1 was replaced with H-mordenite having a silica / alumina ratio of 46, and used as an adsorbent.
[0012]
Comparative Example 1
A cobalt ion exchange mordenite was obtained in the same manner as in Example 1 except that the H-mordenite of Example 1 was replaced with H-mordenite having a silica / alumina ratio of 121, and used as an adsorbent.
Comparative Example 2
Cobalt ion exchange mordenite was obtained in the same manner as in Example 1 except that H-mordenite having a silica / alumina ratio of 211 was used instead of H-mordenite, and used as an adsorbent.
[0013]
Test Example After pressing the adsorbents of Examples 1 to 3, the particles were sized to 10 to 20 mesh, filled in a quartz glass reaction tube having an inner diameter of 20 mm, and adsorbed by a normal pressure fixed bed flow type reaction apparatus. The trimethylamine ((CH ₃ ) ₃ N) adsorption / desorption characteristics of the compound were examined.
The test conditions are shown below.
Space velocity: 30000h ^-1
Adsorption temperature: 25 ° C
Trimethylamine (CH ₃ ) ₃ N concentration: 20 ppm (residual air)
In the test, air containing 20 ppm of (CH ₃ ) ₃ N was passed through the adsorbent layer, and was adsorbed until the rate of removal of (CH ₃ ) ₃ N by the adsorbent became from 100% to 10% (CH ₃ ). _The amount of 3N is defined as the adsorption capacity. Thereafter, the adsorbent layer is heated at a rate of 5 ° C./min to desorb (CH ₃ ) ₃ N from the adsorbent.
_{(CH 3) 3} N analysis of, _{(CH 3)} a ₃ N was converted to NOx by Pt / alumina-based catalyst, it was continuously measured by NOx monitor.
[0014]
FIG. 2 shows the adsorption performance of (CH ₃ ) ₃ N by the adsorbents obtained in Examples and Comparative Examples. It can be seen that when H-mordenite having a silica / alumina ratio of 10 to 50 is used, a very large amount of adsorption can be obtained.
FIG. 3 shows the desorption characteristics of (CH ₃ ) ₃ N of the adsorbent obtained in the example. Compared to unmodified H-mordenite (silica / alumina ratio 23), it can be seen that the desorption temperature of (CH ₃ ) ₃ N ₃ moves to a lower temperature in the adsorbent of the example and desorbs at 300 ° C. or lower. Therefore, when it is used in the odor removal system shown in FIG.
[0015]
【The invention's effect】
ADVANTAGE OF THE INVENTION According to this invention, since an adsorbent can be regenerated and reused at lower temperature, a large amount of exhaust gas containing a trace amount of malodorous components can be treated efficiently and at low cost.
[Brief description of the drawings]
FIG. 1 is a diagram showing a configuration of an apparatus using an adsorbent according to one embodiment of the present invention.
FIG. 2 is a graph showing the adsorption performance of (CH ₃ ) ₃ N by the adsorbents obtained in Examples and Comparative Examples of the present invention.
FIG. 3 is a graph showing (CH ₃ ) ₃ N desorption characteristics of an adsorbent obtained in an example of the present invention and comparison with unmodified H-mordenite.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 ... Adsorbent layer (heat exchanger) 2 ... Auxiliary combustion furnace 3 ... Combustion catalyst layer

Claims (3)

After adsorbing and concentrating malodorous components such as ammonia and amines in the exhaust gas on the adsorbent, intermittently heating the adsorbent and burning and removing the malodorous components desorbed from the adsorbent include copper and manganese. A method for removing an offensive odor, comprising using an adsorbent obtained by ion exchange of H-mordenite having a silica / alumina molar ratio of 10 to 50 with at least one ion selected from the group consisting of iron, cobalt and iron. 2. The malodor control device according to claim 1, wherein a heating catalyst is used to desorb the malodor component adsorbed and concentrated on the adsorbent, and a combustion catalyst is used to burn off the malodor component desorbed from the adsorbent. Removal method. An adsorbent for malodorous components which is easy to adsorb and desorb malodorous components composed of components obtained by ion-exchanging H-mordenite having a silica / alumina molar ratio of 10 to 50 with one or more ions selected from the elements copper, manganese, cobalt and iron.

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