JP2002136871A - Exhaust gas treatment catalyst and production method thereof - Google Patents

Abstract

(57) [Problem] To provide a catalyst for decomposing and removing harmful components in exhaust gas discharged from an incinerator and the like, and a method for producing the same. A catalyst for decomposing harmful substances in exhaust gas in which a catalytically active component is supported on a carrier containing titanium oxide as a main component, wherein the catalyst has at least three peaks in the pore size distribution, and the first peak is The second peak ranges from 300 nm to 450 nm, the second peak ranges from 50 nm to 100 nm, and the third peak
The exhaust gas treatment catalyst according to any one of claims 1 to 3, characterized in that the peak of (i) is in the range of 30 nm or less, and contains an oxide of at least one metal of Cr, Co, Fe, Cu and Mn as a catalytically active component.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an exhaust gas treatment catalyst, particularly to a catalyst for decomposing an organic halogen compound, and more particularly to an exhaust gas generated from a municipal waste incinerator, an industrial waste incinerator, a chemical plant, a steel mill, and the like. The present invention relates to a catalyst for decomposing and removing organic halogen compounds harmful to the human body, particularly dioxins and organic halogen compounds such as dioxin precursors such as halobenzenes and halophenols, and a method for producing the same. Here, dioxins are a general term for polyhalodibenzo-para-dioxins, polyhalodibenzofurans, and coplanar-polyhalobiphenyls.

[0002]

2. Description of the Related Art Conventionally, for the treatment of organic chlorine compounds contained in exhaust gas from municipal waste incinerators and the like, adsorption removal by activated carbon and decomposition removal by a catalyst have been performed. Among these, in the method using a catalyst, a conventional denitration catalyst is used as it is, or the catalyst is used as an oxidation decomposition catalyst for an organic chlorine compound by partially improving the oxidation ability by utilizing the oxidation ability of the denitration catalyst,
An example in which the catalyst is used as a simultaneous denitration catalyst is known.

As a catalyst for removing organic halogen compounds, JP-A-10-235191 contains titanium oxide as a catalyst component and has a thickness of 0.01 μm to 0.05 μm.
Pore group having a pore size distribution peak in the range of 0.1 μm
There is disclosed a catalyst for removing an organic halogen compound having pores including a pore group having a pore diameter distribution peak in a range of m to 0.8 μm and containing vanadium oxide and / or tungsten oxide as a catalyst component.

[0004]

In the decomposition treatment of an organic halogen compound using a catalyst, a denitration catalyst using ammonia or the like as a reducing agent has been used as it is or partially modified to use an organic halogen compound and NOx. A method for simultaneous removal is known, but in this case, the catalyst itself is designed and manufactured on the premise of simultaneous treatment of both, and is always optimized for the purpose of catalytic oxidative decomposition of an organic halogen compound. is not.

The above-mentioned Japanese Patent Application Laid-Open No. 10-235191 discloses an invention directed to organic halogen compounds such as dioxins, but the effect on dioxins is limited to pores of 0.01 μm to 0.05 μm only. Although there is a slight advantage in comparison with the case where is present, no advantage over other various pore distribution morphologies is shown. Therefore, at present, the pore structure of the catalyst most effective for organic halogen compounds having a relatively large molecular structure such as dioxins has not been elucidated.

Further, it is disclosed that vanadium oxide and tungsten oxide are contained as catalytically active components. However, the superiority of vanadium oxide and tungsten oxide as compared with other element species is not shown at all. In this respect, it can be said that the most effective catalytically active component for organic halogen compounds such as dioxins has not been clarified yet. An object of the present invention is to provide an exhaust gas treatment catalyst suitable for decomposing and removing organic halogen compounds, particularly chlorinated and brominated dioxins, in exhaust gas discharged from an incinerator and the like, and a method for producing the same.

[0007]

The invention claimed in the present application is as follows. (1) A catalyst for decomposing an organic halogen compound in an exhaust gas in which a catalytically active component is supported on a carrier containing titanium oxide as a main component, wherein the catalyst has at least three peaks in pore size distribution, and the first peak is Range from 300 nm to 450 nm,
The second peak is in the range of 50 nm to 100 nm, and the third peak is in the range of 30 nm or less, and an oxide of at least one metal of Cr, Co, Fe, Cu and Mn is used as the catalytically active component. An exhaust gas treatment catalyst containing an organic halogen compound, comprising:

(2) The ratio of the pore volume corresponding to the three peaks is 10% with respect to the total pore volume.
(2) The exhaust gas treatment catalyst according to (1), wherein the second peak is in the range of 10% to 60%, and the third peak is in the range of 30% to 80%. (3) The exhaust gas treatment catalyst according to (1) or (2), wherein the catalyst active component is contained in an amount of 1% by weight or more of the whole catalyst. (4) A titania particle having a particle size of 5 nm to 600 nm is prepared as a titania raw material, and a thermally decomposable substance having a particle size equal to or larger than a target pore size of the catalyst is kneaded as a porosifying agent,
Calcination to form the first peak of the pore size distribution, pores of other pore sizes are formed as gaps between the titania particles, and a catalytically active component is added at any stage during the preparation of the catalyst. (1)-(3)
A method for producing the exhaust gas treatment catalyst described in the above.

The subject of the present invention is an exhaust gas containing an organic halogen compound such as an organic chlorine compound and an organic bromine compound generated from a municipal solid waste incinerator or the like, particularly chlorinated and brominated dioxins, and halobenzenes and halophenols. It is an exhaust gas containing an organic halogen compound having a molecular weight of about 50 to 650, such as a dioxin precursor. In particular, it has high decomposition performance for organic halogen compounds having a molecular weight of about 100 to 450, and higher decomposition performance can be obtained for organic halogen compounds having a molecular weight of about 300 to 400. If the molecular weight is out of this range, the diffusion of the reaction molecules is difficult to promote because the pore structure of the catalyst is not suitable,
Sufficient catalytic performance cannot be obtained.

The catalyst of the present invention has at least three peaks in the pore diameter portion of the catalyst in order to reduce the diffusion resistance of molecules having a size of the above-described dioxins in the pores and improve the catalytic performance. 1 peak is 300 nm to 450 n
m, preferably in the range of 350 nm to 450 nm (more preferably 380 nm to 420 nm), and the second peak is 50 nm to 100 nm, preferably 75 nm to 100 n.
m (more preferably 90 nm to 100 nm),
And the third peak is 30 nm or less, preferably 20 n
m. Incidentally, the pore size distribution of the catalyst in the present invention was measured by a mercury intrusion method,
This is a value read from the differential pore volume distribution diagram.

In general, a catalyst having a large specific surface area is more advantageous in terms of catalytic performance because the number of active points is increased. Therefore, from the viewpoint of the pore structure of the catalyst, the pores are as small as possible (the third pores in the present invention). (Corresponding to peaks) are preferred. However, even when a catalyst having only a small pore and a large specific surface area (and thus a large number of active points) is produced, reactive molecules in the gas phase outside the catalyst diffuse from the outer surface of the catalyst to the active points inside the catalyst. Otherwise, the catalyst performance will not improve. The presence of large-diameter pores corresponding to the first peak of the present invention works very effectively to promote the diffusion of reactive molecules, that is, to reduce the diffusion resistance. Naturally, if the abundance ratio of the large-diameter pores increases, the void portion increases from the viewpoint of effective utilization per volume of the catalyst, so that useless space is created, and as a result, the specific surface area decreases. However, this is disadvantageous as a whole catalyst performance. Therefore, by providing medium-sized pores (pores corresponding to the second peak in the present invention), useless voids in the catalyst are filled, which is advantageous in terms of specific surface area and reduces the size of reactive molecules. Since it can also play a role as a passage leading from the pores to the small pores, the catalyst performance becomes very advantageous, and a higher performance of the catalyst can be expected.

The reason why the first peak has a suitable range is that if the pores corresponding to the first peak are too wide, the diffusion rate of the reaction molecules becomes saturated and the specific surface area of the entire catalyst becomes small. Is considered to be disadvantageous, and if the pores corresponding to the first peak are too narrow, the diffusion of the reaction molecules becomes insufficient, which is also considered to be disadvantageous in terms of catalytic performance. It is considered that the arrangement of the second peak, in which the specific surface area and the diffusion of the reactive molecule are most balanced between the first peak and the third peak, is a preferable range. The preferable range of the third peak is that the pore corresponding to the third peak most contributes to the specific surface area of the catalyst. It is considered to be advantageous.

The first peak catalyst pore size distribution has an effect of reducing the diffusion resistance of dioxins inside the catalyst, and the second peak catalyst pore size distribution coexists with the first peak. It has the function of inducing dioxins approaching via the pore size of the first peak to the pore size distribution of the third peak. The pore size distribution of the third peak coexists with the first and second peaks and the first peak. And acts to finally capture dioxins not captured by the pore size distribution of the second peak.

In the catalyst of the present invention, the carrier is titanium oxide and the catalytically active components are Cr, Co, Fe, Cu and M.
n is an oxide of at least 1% by weight of the total weight of the catalyst, preferably 5% by weight of the total weight of the catalyst.
The content is more preferably 10% by weight or more. If the amount of the catalytically active component is less than 1% by weight, sufficient catalytic performance cannot be obtained. However, since the catalytic performance tends to be saturated with an increase in the content of the catalytically active component, it is not always advantageous when the catalytically active component is excessively present (for example, 50% by weight or more). Here, the carrier refers to the characteristics of the catalyst component (catalytic activity, selectivity, life, mechanical strength, etc.)
The carrier itself has no activity or is at least lower in activity than the catalyst component ("Catalyst Lecture Vol. 5, Catalyst Design", edited by the Catalysis Society of Japan, 1985, Kodansha). Further, the catalyst component and the carrier are distinguished based on the function, content, distribution state, and the like of each constituent chemical species in the prepared catalyst irrespective of the catalyst preparation method described later.

The specific surface area of the catalyst in the present invention is 50 m ^2.
/ G or more, preferably 75 m ² / g or more, more preferably 100 m ² / g or more. The specific surface area is 50m ² /
If it is less than g, the catalyst performance per unit volume will not be sufficient.

As a method for producing the catalyst of the present invention, one or more kinds of titania particles having a particle size of 5 nm to 600 nm as a titania raw material (in this case, the titania particles are composed of single crystals or dense polycrystalline particles) Primary particles or secondary particles substantially composed of primary particles) and a porogen (for example, having a particle size of 50 nm to 1000
nm easily thermally decomposable compound) and a catalytically active component (Cr, C
o, Fe, Cu, Mn), a method of kneading, shaping and shaping the mixture, in the same manner as described above, having one or more particle diameters of 5 nm to 600 nm. Titania particles (in this case, the titania particles are primary particles composed of a single crystal or a dense polycrystalline particle, or secondary particles composed substantially of a primary particle) are used as a carrier material to form a porous material. Agent (e.g. particle size 5
Kneading, shaping, and sintering together with a readily thermally decomposable compound having a thickness of 0 nm to 1000 nm, and then supporting and sintering a catalytically active component by an impregnation method. The active ingredient may be supported by a coprecipitation method or the like at the time of producing the titania particles. The particle size of the raw material titania particles is in the range of 5 nm to 600 nm, preferably 50 nm to 400 nm, and more preferably 100 nm to 200 nm. If the particle size of the titania particles is out of the above range, it becomes difficult to form pores corresponding to the second peak or pores corresponding to the third peak.

[0017]

The use of the above-mentioned catalyst allows the inside of the catalyst to react with an organic halogen compound, particularly a dioxin molecule which is an organic chlorine compound, or a molecule such as halophenol or halobenzene which is a precursor of dioxin formation. Can be reduced in the pores, thereby improving the efficiency of the catalyst for decomposing organic chlorine compounds. In other words, the organic halogen compound molecules (reactive molecules) have large, medium, and small pores instead of suddenly entering fine pores at the stage of diffusing into the catalyst after passing through the boundary film near the outer surface of the catalyst. In such a case, the organic halogen compound molecules can be easily diffused into the catalyst by sequentially diffusing from relatively large pores to pores having an intermediate size and finally to the smallest pores. The reactive molecules can easily reach active points existing on the surface inside the catalyst, and therefore, the active points inside the catalyst are effectively used, and it is considered that the performance of the entire catalyst is improved.

Further, by selecting a catalyst active component having the highest activity for decomposing dioxins, the efficiency of decomposing dioxins can be further improved. In view of the above, it is appropriate to evaluate the effective utilization rate of the internal surface of the catalyst in order to evaluate the effect of the internal diffusion of the reaction molecule in the catalyst. It is considered more appropriate to use an index based on the surface area. That is, when a mere decomposition rate or reaction rate is used as an index, there is a risk that a catalyst having only a large specific surface area may be evaluated as having high performance, not only whether the effect of internal diffusion is good or bad. In the present invention, the effective utilization rate of the internal surface of the catalyst was compared by comparing the reaction rates per specific surface area.

[0019]

BEST MODE FOR CARRYING OUT THE INVENTION In the process for producing a catalyst according to the present invention, the porogen is a calcination temperature or lower (about 400 ° C. to 80 ° C.).
(0 ° C.), a substance which is easily thermally decomposed, for example, a resin such as an acrylic resin, an acetal resin, and a phenol resin in addition to a methacrylic resin. The particle size of the porous agent is larger than the pore size to be produced. For example, 400n
In the case of opening m pores, a porogen having a particle diameter of 400 nm or more is used. A rough guide is 1.2 of the hole diameter to be produced.
The value is determined by taking into account the physical properties (depending on the type of the resin) of the porogen itself.

The second and third peaks have a particle diameter of 5n.
m to 600 nm of titania particles (in this case, the titania particles are primary particles composed of single crystals or dense polycrystalline grains, or secondary particles composed substantially of primary particles). The gap can be formed by controlling the packing density.

In addition, the second peak of 50 nm to 1 nm
In order to obtain a peak in the range of 00 nm, for example, secondary particles having a particle size of 5 nm to 600 nm can be used as the raw material titania, and can be obtained by kneading and firing. The size of the secondary particles can be controlled by the temperature, pH, and use of a surfactant during the preparation. Further, it can also be controlled by performing a high dispersion treatment with a sand mill. Further, the third peak, that is, a peak in the range of 30 nm or less, can also be formed as a gap between primary particles of titania. The gap between the primary particles can be formed by appropriately selecting the particle size of the primary particles themselves and the production condition of the secondary particles so as to obtain a target pore size.

The pores of the catalyst are formed during the production of the titania carrier.
Either the impregnation method or the coprecipitation method may be used. In the case of the kneading method or the like, the active component is supported at the same time as the carrier preparation (pore formation), and in the case of the impregnation method or the like, the active component is supported after the carrier preparation (after pore preparation). . In the case of the coprecipitation method, the active ingredient is supported on the titania raw material before the preparation of the carrier (before the preparation of the pores).

In the kneading method, Cr and C are used as catalytically active components.
o, an oxide of a metal of at least one of Fe, Cu and Mn, and a raw material that changes to an oxide during firing, such as a hydroxide of these metals (or metal oxide ions); Halides, ammonium salts,
Complex compounds such as sulfate, carbonate, acetate, alkoxide, acetylacetonate and the like may be mixed.

In the case of the impregnation method, at least one metal selected from the group consisting of Cr, Co, Fe, Cu and Mn is used as a catalytically active component on a titanium oxide carrier (powder, granule, plate, rod, honeycomb, etc.). An object is supported. When the titanium oxide is powder or slurry, Cr, Co, Fe, C
The active metal component is mixed with a solution of a complex compound such as a hydroxide, halide, ammonium salt, sulfate, carbonate, acetate, alkoxide, acetylacetonate or the like of a metal (or metal acid ion) of u or Mn. Impregnate. When titanium oxide is a molded body, Cr, Co, Fe,
Hydroxide of metal of Cu, Mn (or metal acid ion),
The active ingredient is impregnated by throwing into a solution of a complex compound such as a halide, ammonium salt, sulfate, carbonate, acetate, alkoxide, acetylacetonate or the like. The order of impregnation is such that only one type or one type of the catalytically active component is added to the titanium oxide.
There are a method in which a plurality of kinds are supported by each kind, and a method in which a plurality of catalytically active components are simultaneously impregnated in titanium oxide.

In the case of the coprecipitation method, an aqueous solution of a water-soluble titanium compound (for example, titanyl sulfate) and a water-soluble compound of a catalytically active metal species is prepared, and this is mixed with an appropriate solution so that the pH becomes near neutral. A precipitate is obtained during preparation and with care to avoid excessive heat generation. The precipitate is filtered, washed (washed with water), dried and calcined to obtain a catalyst. It is also possible to carry one catalytically active component in this way and then carry another catalytically active component in another way.

Furthermore, the catalytically active component and / or the carrier component can be prepared singly or simultaneously using a sol-gel method. In the sol-gel method, a metal alkoxide of each component or a complex such as acetylacetonate is dissolved in a predetermined amount in a predetermined organic solvent in a sol-like solution.
A predetermined amount of acid or alkali and water are added to form a gel polymer, which is molded and fired to prepare a target oxide. In preparing the present catalyst, a catalytically active component and / or a carrier component are preliminarily mixed at a predetermined ratio in a sol-like solution stage, and the mixture is gelled and calcined. And then gelling and baking, and a method of individually preparing each oxide fine particle by a sol-gel method, kneading, molding and baking them. Hereinafter, the present invention will be described in more detail with reference to examples.

[0027]

EXAMPLE 90 g of titania powder as shown in Table 1 was used as a raw material powder, and a surface treatment was carried out with a silane coupling agent (KBM603 manufactured by Shin-Etsu Silicone Co., Ltd.) in order to improve moldability. Table 1 similarly shows the particle size of the titania powder used in the preparation, the presence or absence of high dispersion treatment by a sand mill, and the like. 10 g of polymethacrylic acid beads as a porosifying agent and methylcellulose 5 as a binder
g, a plasticizer 7 g, a stearic acid emulsion 1 g as a lubricant, and 11 g to 15 g of distilled water. The molding and baking procedures are as follows. First, a silane coupling agent is put into an aqueous solution adjusted to a predetermined pH with acetic acid and aqueous ammonia, stirred, and then allowed to stand at room temperature for 24 hours. The left standing liquid and the titania powder having the particle size blended are mixed with a homogenizer, and the mixed liquid is dried at 80 ° C. until there is no more water. Then, after pulverizing and classifying, it is mixed with various additives such as a binder, a porosifying agent, and distilled water, and further, active metals such as chromium oxide, cobalt oxide, iron oxide, copper oxide or manganese oxide, and vanadium oxide (oxidized oxide) as a comparative example. Titanium TiO ₂ manufactured by Wako Pure Chemical Industries: Model number 207
-11121 anatase type, cobalt oxide Co ₃ O ₄ manufactured by Kanto Chemical Co., Ltd .: Model No. 08120-08, iron oxide Fe ₂ O
₃ is manufactured by Kanto Chemical Co., Ltd .: Model No. 20074, copper oxide CuO is manufactured by Kanto Chemical Co., Ltd .: Model No. 07503-08, manganese oxide Mn
O ₂ is manufactured by Wako Pure Chemical Industries, Ltd .: Model No. 135-09685, and vanadium oxide V ₂ O ₅ is manufactured by Wako Pure Chemical Industries, Ltd .: Model No. 226-001
25), and the mixture was further kneaded and allowed to stand. After standing for a certain period of time, the mixture was kneaded again and molded. Molding was performed in a noodle shape (pencil shape) using an extrusion jig. After being molded, dried again, and calcined in an oxygen atmosphere at 500 ° C. for 3 hours to prepare a catalyst of the present invention.

[0028]

[Table 1]

The performance of the catalyst obtained as described above was evaluated as follows. Using a fixed-bed microreactor, the reaction temperature was 200 ° C., and the W / F was 0.017 (g · min /
ml), the reaction gas has an indicator substance concentration of 300 ppm and an oxygen concentration of 1
A test for evaluating the performance of the catalyst with respect to the decomposition of the organic halogen compound was performed at a nitrogen balance of 0%. Here, as examples of the organic halogen compound, o-chlorophenol (Examples A and B) and o-bromophenol (Example C), which are alternative indicators of dioxins, were used. Regarding the indicator substances used, see Inaba et al .: Proceedings of the 8th Annual Meeting of the Society of Waste Management, p558, Kanda et al .: Proceedings of the 1997 Annual Conference of the Catalysis Society of Japan, p114, Tanaka et al .: The 8th Annual Meeting of the Japan Opportunity Society Engineering Symposium '98 Lecture Papers p1
Studies such as 82 have shown that the decomposition properties are similar to those of dioxins. The specific surface area of the catalyst was measured by a multipoint BET method using nitrogen adsorption. The pore distribution was measured with a mercury intrusion porosimeter and read from a differential pore volume distribution diagram.

Example A: Effect of pore distribution and catalytically active components Table 2 shows the results of measurement of catalytic activity and pore distribution of Comparative Examples A1 to A3 and Examples A1 to A5. The catalytic activity was expressed on the basis of the specific surface area, using the decomposition reaction rate constant of the indicator substance o-chlorophenol (calculated assuming that the order of the reaction was 1st order), and expressed as a comparative value based on the case of Comparative Example A3. (K / K0 in the table). The amount of the catalytically active component carried was 10 wt%.

[0031]

[Table 2]

Comparative Example A1 has a two-pore structure.
Comparative Example A3 and Examples A1 to A5 are samples having three peaks in the pore structure. Table 2 shows that a comparison between Comparative Example A1, Comparative Example A3, and Examples A1 to A5 shows that the catalyst having the three-peak pore structure has higher activity than the two-peak pore structure. Comparative Example A2 has three peaks in the pore structure, whereas a large pore has a peak between 100 nm and 300 nm. Comparative Example A3 and Examples A1-A5 have a large pore having a peak between 300 nm and 450 nm. It is a sample having. From Table 2, Comparative Example A2, Comparative Example A3 and Example A
When comparing 1 to A5, the large pores are 300 nm to 450 n
It can be seen that the sample having a peak between m is more active.

In Comparative Example A3, the catalytically active component was vanadium oxide, and in Examples A1 to A5, the catalytically active components were chromium oxide, cobalt oxide, iron oxide, copper oxide, and manganese oxide. This is a sample having a pore structure. Comparison of Comparative Example A3 with Examples A1 to A5 shows that Examples A1 to A5 have higher activity in all cases.

Example B1: Effect of catalytically active component (chromium oxide), indicator: o-chlorophenol Chromium oxide as catalytically active component 0.1 wt% of the entire catalyst
% To 50 wt% of the catalyst was prepared and the decomposition test of o-chlorophenol was performed. The results are shown in Table 3. The catalytic activity was shown as a comparative value based on the case of Example B1-2 using the rate constant of the decomposition reaction of o-chlorophenol on the basis of the specific surface area (K / K0 column in the table). From these results, it can be seen that the activity is high when the active component is at least 5% by weight of the total weight of the catalyst, and particularly high when the active component is at least 10% by weight. Further, it is found that sufficient activity cannot be obtained when the content is 1% by weight or less.

[0035]

[Table 3]

Example B2: Effect of catalytically active component (cobalt oxide), indicator: o-chlorophenol Cobalt oxide as catalytically active component was 0.1 w of the entire catalyst.
Table 4 shows the results of preparing a catalyst containing t% to 50 wt% and performing an o-chlorophenol decomposition test. The catalytic activity was represented by a comparative value based on the case of Example B2-2 using the rate constant of decomposition reaction of o-chlorophenol on the basis of the specific surface area (K / K0 column in the table). From these results, it can be seen that the activity is high when the active component is at least 5% by weight of the total weight of the catalyst, and particularly high when the active component is at least 10% by weight. Further, it is found that sufficient activity cannot be obtained when the content is 1% by weight or less.

[0037]

[Table 4]

Example B3: Effect of catalytically active component (iron oxide), indicator substance: o-chlorophenol Iron oxide as catalytically active component is 0.1 wt% or more of the whole catalyst.
Table 5 shows the results of preparing a catalyst containing 50 wt% and performing an o-chlorophenol decomposition test. The catalytic activity was shown as a comparative value based on the case of Example B3-2 using the rate constant of decomposition reaction of o-chlorophenol on the basis of the specific surface area (column of K / K0 in the table). From these results, it can be seen that the activity is high when the active component is at least 5% by weight of the total weight of the catalyst, and particularly high when the active component is at least 10% by weight. Further, it is found that sufficient activity cannot be obtained when the content is 1% by weight or less.

[0039]

[Table 5]

Example B4: Effect of catalytically active component (copper oxide), indicator substance: o-chlorophenol Copper oxide as catalytically active component was 0.1 wt% or more of the whole catalyst.
Table 6 shows the results of preparing a catalyst containing 50 wt% and performing an o-chlorophenol decomposition test. The catalytic activity was shown as a comparative value based on the case of Example B4-2 using the rate constant of decomposition reaction of o-chlorophenol on the basis of the specific surface area (K / K0 column in the table). From these results, it can be seen that the activity is high when the active component is at least 5% by weight of the total weight of the catalyst, and particularly high when the active component is at least 10% by weight. Further, it is found that sufficient activity cannot be obtained when the content is 1% by weight or less.

[0041]

[Table 6]

Example B5: Effect of catalytically active component (manganese oxide), indicator: o-chlorophenol Manganese oxide as catalytically active component 0.1 w of the entire catalyst
Table 7 shows the results of preparing a catalyst containing t% to 50 wt% and performing an o-chlorophenol decomposition test. The catalytic activity was represented by a comparative value based on the case of Example B5-2 using the rate constant of decomposition reaction of o-chlorophenol on the basis of the specific surface area (K / K0 column in the table). From these results, it can be seen that the activity is high when the active component is at least 5% by weight of the total weight of the catalyst, and particularly high when the active component is at least 10% by weight. Further, it is found that sufficient activity cannot be obtained when the content is 1% by weight or less.

[0043]

[Table 7]

Example C: Effect of catalytically active component, indicator substance: o-bromophenol A catalyst containing chromium oxide, cobalt oxide, copper oxide, iron oxide and manganese oxide as a catalytically active component in an amount of 10% by weight of the whole catalyst Examples A1 to A5) and o
Table 8 shows the results of the bromophenol decomposition test. The catalytic activity was represented by a comparative value based on the case of Comparative Example C6 using the decomposition reaction rate constant of o-bromophenol on the basis of the specific surface area (K / K0 column in the table). The sample of Comparative Example C6 is the same as Comparative Example A3. From the test results, it can be seen that each of the catalysts of Examples C1 to C5 has higher activity than the case of vanadium of Comparative Example C6. Therefore, even when the indicator substance was o-bromophenol, all of the examples exhibited high decomposition performance, and it was found that the present invention was also effective for decomposing organic bromine compounds.

[0045]

[Table 8]

[0046]

According to the present invention, by optimizing the catalyst active component simultaneously with the pore size distribution of the catalyst, organic halogen compounds, particularly dioxins thereof, in the exhaust gas discharged from an incinerator or the like are decomposed and removed. And a method for producing the same. The present invention is particularly included in the exhaust gas from incineration treatment equipment for waste plastics such as organic chlorine compounds (chlorinated dioxins, chlorinated benzenes, and chlorinated phenols) contained in exhaust gas from municipal waste incinerators and the like, and household electric appliances. This is an effective technique for detoxifying organic bromine compounds (brominated dioxins, brominated benzenes, and brominated phenols).

Continued on the front page (51) Int.Cl. ⁷ Identification symbol FI Theme coat II (reference) B01J 23/75 C07B 35/06 35/04 37/06 35/10 301 C07D 319/24 C07B 35/06 B01D 53/36 ZABG 37/06 B01J 23/74 301A // C07D 319/24 311A (72) Inventor Nobuyasu Kanda No. 1, Yawata Kaigandori, Ichihara-shi, Chiba F-term (reference) 4D048 AA11 AB03 BA07X BA25X BA28X BA28X BA35X BA36X BA37X BA41X BB06 4G069 AA02 AA08 BA04A BA04B BA22C BB04A BB04B BC31A BC31B BC58A BC58B BC62A BC62B BC66A BC66B BC67A BC67B CA02 CA10 BA19 BA05 BA30 BA05 BA18 BA18 BA18 BA55 BA56 BA81 BA85

Claims (4)

[Claims] 1. A catalyst for decomposing an organic halogen compound in an exhaust gas in which a catalytically active component is supported on a carrier containing titanium oxide as a main component, wherein the catalyst has at least three peaks in pore size distribution, and 300 nm to 450 nm peak
, The second peak is in the range of 50 nm to 100 nm,
And an organic halogen compound characterized by having a third peak in the range of 30 nm or less, and containing an oxide of at least one metal of Cr, Co, Fe, Cu and Mn as the catalytically active component. Exhaust gas treatment catalyst. 2. The ratio of the pore volume corresponding to the three peaks is 10% to 6% with respect to the total pore volume.
2. The method according to claim 1, wherein the second peak is in the range of 10% to 60%, and the third peak is in the range of 30% to 80%.
An exhaust gas treatment catalyst according to the above. 3. The exhaust gas treatment catalyst according to claim 1, wherein the catalytically active component is contained in an amount of 1% by weight or more of the whole catalyst. 4. A titania raw material having a particle size of 5 nm to 60 nm.
A titania particle of 0 nm is prepared, and a thermally decomposable substance having a particle size equal to or larger than a target pore size of the catalyst is kneaded as a porosifying agent, followed by firing to form a first peak of the pore size distribution. The method for producing an exhaust gas treatment catalyst according to any one of claims 1 to 3, wherein the pores having a pore diameter of (i) are formed as gaps between the titania particles, and a catalytically active component is added at any stage during the preparation of the catalyst. .