JP2000157872A - Halogen-containing organic compound-decomposing catalyst, production thereof, and waste gas treatment method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To decompose halogen-containing organic compounds at high efficiency for a long duration by preventing deterioration of catalytic activity by deliquescent components. SOLUTION: This halogen-containing organic compound-decomposing catalyst comprises a component having a function of oxidizing and decomposing halogen- containing organic compounds, and a coating formed on the component has a coating containing an organic porous component, a mixture coating containing an organic porous component and an inorganic oxide particle or a mixture coating containing an organic porous component and a catalyst component particle formed thereon. The method for producing the halogen-containing organic compound decomposition catalyst comprises applying at least one type of slurries or emulsions containing components selected from an organic porous component, a mixture containing an organic porous component and an inorganic oxide particle, and a mixture containing an organic porous component and a catalyst component particle to the surface of a halogen-containing organic compound decomposition catalyst and forming a porous coating by drying the resultant halogen-containing organic compound decomposition catalyst.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a catalyst for decomposing a halogen-containing organic compound, a method for producing the same, and an exhaust gas treatment method, and more particularly, to an exhaust gas containing a deliquescent component such as an alkali metal or an alkaline earth metal (particularly, an exhaust gas from a garbage incinerator). TECHNICAL FIELD The present invention relates to a halogen-containing organic compound decomposition catalyst suitable for efficiently purifying a halogen-containing organic compound such as dioxin for a long period of time, a production method thereof, and an exhaust gas treatment method.

[0002]

2. Description of the Related Art Halogenated aromatic compounds discharged from refuse incinerators and the like, particularly substances generally called dioxins, such as polychlorinated dibenzodioxins and polychlorinated dibenzofurans, are extremely toxic. Cancer has become a serious problem, and new emission guidelines have been strictly regulated by the Ministry of Health and Welfare.

Many studies have been made on dioxin purifying catalysts and purifying methods. For example, JP-A-5-245343 discloses that Ti, Si, Zr, A
A component selected from l and V and containing V, Pt,
Using a catalyst containing a B component selected from the group consisting of Pd, Ru, Mn, Cu, Cr and Fe, a temperature range of 150 to 450 ° C., a space velocity of 20,000 h ⁻¹ or less, and a catalyst surface area 1 m ² per gas volume 100m ³ / Hr (at te
A method for purifying under the condition of mp) has been proposed. JP-A-4-284849 proposes a purification method using an acidic zeolite or a catalyst obtained by carrying and / or ion-exchanging a transition metal on an acidic zeolite. Further, JP-A-4-503772 discloses a purification method. A denitration catalyst or a modified denitration catalyst such as a titanium oxide type, an iron oxide type or a zeolite type, particularly, in the case of a titanium oxide type, having a titanium content of 70% by weight or more and tungsten oxide as a donor,
A purification method has been proposed in which a catalyst containing molybdenum oxide and / or vanadium oxide is treated under an oxidizing condition at a temperature of 150 to 500 ° C.

[0004] However, the catalyst used in the above method has a drawback that the catalytic activity is remarkably reduced in the treatment of exhaust gas containing a deliquescent component. For example, when an exhaust gas containing a highly deliquescent component such as an alkali metal and an alkaline earth metal, which is contained in a large amount in an exhaust gas discharged from a garbage incinerator, is treated with a catalyst that decomposes the halogen-containing organic compound, alkali salts are removed. It adheres to the catalyst surface together with the dust, and further absorbs the moisture in the exhaust gas to cause deliquescence of the alkali salts. The deliquescent alkali salts infiltrate into the inside of the catalyst from between the catalyst particles, block the pores in the catalyst, and react with the catalyst components to alter the active site,
Significantly reduces the activity of the catalyst. This phenomenon is promoted by condensation that occurs when the temperature of the catalyst layer rises and falls particularly when the startup and shutdown are performed. Therefore, measures have been taken to prevent the deliquescent component from entering the inside of the catalyst, thereby reducing catalyst activity, such as maintaining the catalyst layer at a high temperature even during startup and stopping to prevent deliquescent. There was a problem that the running cost became very high.

[0005]

SUMMARY OF THE INVENTION An object of the present invention is to solve the above-mentioned problems of the prior art, to prevent a decrease in catalytic activity due to a deliquescent component, and to efficiently decompose a halogen-containing organic compound for a long period of time. It is an object of the present invention to provide a halogen-containing organic compound decomposing catalyst, a method for producing the same, and an exhaust gas treatment method.

[0006]

Means for Solving the Problems The present inventors have conducted intensive studies on the above-mentioned problems, and as a result, have formed a film of an organic porous component on the surface of a component having a function of oxidatively decomposing a halogen-containing organic compound, thereby obtaining water repellency. To prevent the deliquescent component from entering the inside of the catalyst, thereby achieving the above object, and arrived at the present invention. That is, the invention claimed in the present application is as follows.

(1) An organic porous component film, which has a function of oxidizing and decomposing a halogen-containing organic compound,
A halogen-containing organic compound decomposition catalyst, wherein a mixed film of an organic porous component and inorganic oxide particles or a mixed film of an organic porous component and catalyst component particles is formed. (2) The halogen according to (1), wherein the catalyst contains at least one metal oxide of Ti, Zr, Si and Al and at least one metal oxide of V, Mo and W. Containing organic compound decomposition catalyst. (3) The catalyst comprises Pt, Pd, Ru,
The catalyst for decomposing a halogen-containing organic compound according to (1), comprising at least one noble metal component of Rh and Ir. (4) The catalyst comprises Cr, Mn, Fe,
The halogen-containing organic compound decomposition catalyst according to (1), further comprising at least one transition metal component of Co, Ni, and Cu.

(5) The organic porous component contains at least one of a fluorine resin, an acrylic resin, a polyamide resin and a silicone resin.
The catalyst for decomposing a halogen-containing organic compound according to any of (4). (6) decomposing at least one slurry or emulsion selected from the group consisting of an organic porous component, a mixture of an organic porous component and inorganic oxide particles, and a mixture of an organic porous component and catalyst component particles into a halogen-containing organic compound; A method for producing a halogen-containing organic compound decomposition catalyst, which is applied to the surface of a catalyst and then dried to form a porous film. (7) An exhaust gas treatment method comprising decomposing a halogen-containing organic compound by bringing an exhaust gas containing a deliquescent component into contact with the catalyst according to any of (1) to (6) at a temperature of 120 to 350 ° C. .

[0009]

A film containing an organic porous component is formed on the surface of the catalyst according to the present invention. The organic porous component has a large contact angle with a liquid deliquescent of water or alkali salts and has a high water repellency. It has a function, so even if the alkali salts attached to the catalyst surface deliquesce and become liquid, these liquids can be spheroidized and repelled on the catalyst surface, and the inside of the catalyst due to the surface tension of the deliquescent component Can be prevented.
As a result, a decrease in catalytic activity due to blockage of the catalyst pores and deterioration of the active site is prevented. On the other hand, an organic porous film repels a liquid by a function of water repellency by a contact angle, but does not hinder a decomposition reaction of a halogen-containing organic compound by a catalyst because a gas such as a reaction gas or a vapor passes therethrough. Therefore, by using the catalyst of the present invention, even when the deliquescent component is contained in the exhaust gas, the catalyst activity can be maintained at a high level for a long period of time without maintaining the catalyst layer at a high temperature when the apparatus is stopped. Can be.

[0010]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Components having a function of oxidatively decomposing a halogen-containing organic compound used in the present invention include:
There is no particular limitation on components capable of oxidizing and purifying halogen-containing organic compounds such as dioxins.
r, at least one metal oxide of Si and Al,
A catalyst composition to which at least one metal oxide of V, Mo and W is added can be used. By using such a catalyst composition, not only halogen-containing organic compounds but also nitrogen oxides can be removed with high efficiency.

Further, Pt, Pd, and Pt which are excellent in decomposing performance of a halogen-containing organic compound even in the presence of NOx, SOx, etc.
Use a noble metal based catalyst composition containing at least one of Ru, Rh and Ir, and a transition metal based catalyst composition containing at least one of Cr, Mn, Fe, Co, Ni and Cu which is excellent in oxidative decomposition of halogen-containing organic compounds. You can also. The catalyst composition described above, on the surface of the catalyst composition,
In order to easily form a film of an organic porous component described later, it is usually used as a molded product formed into a plate, a honeycomb, a granule, or the like. For example, the plate-like molded body is obtained by embedding the catalyst composition between the mesh-like inorganic fiber base materials and between the meshes.

In the present invention, as the organic porous component, an organic water-repellent resin such as a fluororesin, an acrylic resin, a polyamide resin and a silicone resin is used, and these may be used alone or in combination of two or more. . The film of the organic porous component, for example, by dispersing the fine particles of the organic water-repellent resin in water to form a slurry or an emulsion, and brushing the molded product of the catalyst composition with a brush, a roller,
It can be formed by applying by spraying or impregnating a molded body, and then drying and evaporating water. Instead of a slurry in which organic water-repellent resin particles are dispersed alone, a slurry in which inorganic oxide particles such as silica are co-dispersed or a slurry in which catalyst component particles are co-dispersed can also be used. Those containing a large amount of an organic binder or the like in the components may be removed by firing after forming the film.

The fine particles of the organic water-repellent resin may be spherical fine particles or fine fibrous materials such as fibrils. In general, the size of the fine particles is preferably 500 ° or more so as not to enter the pores of the catalyst and block. In addition, when the thickness of the organic porous component coating is increased, the water repellent effect is improved, but the diffusion of exhaust gas into the catalyst is hindered, the activity of the catalyst is easily reduced, and the cost is increased. On the other hand, when the thickness of the film is reduced, a portion where the film is not formed is apt to be formed, and the deliquescent alkali solution enters from there, and the catalyst is easily deteriorated, so that a thin and dense film is formed. Is preferred. To this end, a dispersion containing a low-concentration organic water-repellent resin is applied to the catalyst surface in advance and dried,
It is preferable that a dispersion containing an organic water-repellent resin having a concentration higher than the above concentration is further applied and dried.

In order to decompose the halogen-containing organic compound in the exhaust gas containing the deliquescent component using the catalyst of the present invention, the catalyst and the exhaust gas must be decomposed in view of the activity, decomposition efficiency, running cost or durability of the catalyst. The contact is preferably carried out at a temperature of ~ 350 ° C, more preferably 200 ° C.
温度 250 ° C.

[0015]

EXAMPLES Hereinafter, the present invention will be described in more detail with reference to Examples, but the present invention is not limited thereto. Example 1 Titanium oxide powder and ammonium metavanadate
Add oxalic acid and water, knead with a kneader, and adjust the atomic ratio (V / T
A catalyst paste having i) of 10/90 was prepared. On the other hand, 1400 twisted yarns of E glass fiber having a fiber diameter of 9 μm
A mesh of titania, silica sol and polyvinyl alcohol was impregnated and dried in a net-like material plain woven at 0 pieces / inch to produce a rigid catalyst substrate.

The catalyst paste is sandwiched between two catalyst base materials, a 1.0 mm-thick plate-like molded product is molded through a rolling roller, and the molded product is air-dried in the air for 12 hours.
It was calcined at 0 ° C. for 2 hours to obtain a plate catalyst. This plate-like catalyst was cut into a size of 20 × 100 mm for activity measurement, and the fluororesin concentration of a fluororesin suspension (MDF dispersion, 30-J, manufactured by DuPont Fluorochemicals, Mitsui) was reduced to 36% by weight. The solution was impregnated, drained, and dried in the air. This process was repeated twice to form an organic porous film on the catalyst surface. The thickness of the film at this time is about 0.05mm
Met.

EXAMPLE 2 To titanium oxide powder, ammonium molybdate and ammonium metavanadate, oxalic acid, inorganic fiber (trade name: kao wool) for imparting strength and water were added, and the mixture was kneaded with a kneader to obtain an atomic ratio (V / Ti). / Mo) is 7/88/5
Was obtained. The obtained catalyst paste is
In the same manner as in Example 1, sandwiched between two catalyst substrates, a 1.0 mm-thick plate-like molded product was molded through a rolling roller, further air-dried in the air for 12 hours, and then fired at 500 ° C. for 2 hours. To obtain a plate-like catalyst. After cutting the plate-like catalyst into 20 × 100 mm, 10 μl was added to the diluted solution of the fluororesin suspension shown in Example 1.
An organic porous film was formed on the surface of the catalyst in the same manner as in Example 1 using a solution to which the catalyst powder was added by weight%. At this time, the thickness of the film was about 0.05 mm.

Example 3 In Example 2, a catalyst paste having an atomic ratio (V / Ti / W) of 7/88/5 adjusted by using ammonium metatungstate instead of ammonium molybdate was used. A plate-like catalyst was prepared in the same manner as in Example 2, and an organic porous film was formed on the surface of the catalyst.

Example 4 A paste of titanium oxide was rolled on the catalyst substrate shown in Example 1 to obtain a plate-like molded body. The molded body was sucked and impregnated with an aqueous solution of dinitrodiammineplatinic acid so that the supported amount of Pt was 0.5% by weight based on the weight of the catalyst.
It was calcined at 0 ° C. for 2 hours to obtain a plate-like catalyst. An organic porous film was formed on the surface of the catalyst by the same operation as in Example 1.

Example 5 An aluminum oxide paste was rolled on the catalyst substrate shown in Example 1 to obtain a plate-like molded body. An aqueous solution of palladium nitrate was sucked and impregnated into the molded body so that the amount of Pd to be supported was 1% by weight based on the weight of the catalyst, and calcined at 500 ° C. for 2 hours to obtain a plate-like catalyst. An organic porous film was formed on the surface of the catalyst by the same operation as in Example 1 using an acrylic resin emulsion (Campe, water-based acrylic paint). At this time, the thickness of the film was about 0.05 mm.

Example 6 Example 4 differs from Example 4 in that, instead of the dinitrodiammineplatinic acid aqueous solution, a copper nitrate aqueous solution was sucked and impregnated so that Cu was 5% by weight with respect to the catalyst weight. The same operation was performed to form an organic porous film on the plate catalyst.

Example 7 Mn was added to the plate-like molded product obtained in Example 1 in an amount of 5% by weight of the catalyst.
An aqueous solution of manganese nitrate was sucked and impregnated so as to have a weight percentage, and calcined at 500 ° C. for 2 hours to obtain a plate-shaped catalyst. Then, an organic porous film was formed on the surface of the catalyst by the same operation as in Example 1.

Comparative Example 1 In Example 1, the operation of forming an organic porous film on the surface of the plate catalyst was not performed. Comparative Example 2 In Example 4, the operation of forming an organic porous film on the surface of the plate catalyst was not performed.

<Deterioration Test I> Using the plate catalysts obtained in Examples 1 to 7 and Comparative Examples 1 and 2, the decomposition rate of chlorobenzene was measured under the conditions shown in Table 1. Further, about 20% by weight of the catalyst weight of calcium chloride is dispersed on the catalyst surface,
A simulated deterioration test was performed in which the sample was left at room temperature under saturated steam conditions for 24 hours. After the test, the decomposition rate of chlorobenzene and the calcium content in the catalyst were measured using a catalyst in which calcium chloride adhering to the surface was washed with water. The results are shown in Table 2.

<Deterioration Test II> In the above degradation test, a simulation was performed in the same manner as described above, except that the plate catalysts obtained in Example 1 and Comparative Example 1 were used, and sodium sulfate was used instead of calcium chloride. A deterioration test was performed, and the decomposition rate of chlorobenzene and the sodium content in the catalyst after the test were measured. The results are shown in Table 2.

[0026]

[Table 1]

[0027]

[Table 2]

As is clear from Table 2, the decomposition rate of chlorobenzene of the catalyst (Examples 1 to 7) of the present invention in which an organic porous film was formed on the surface to impart water repellency was determined. Although slightly inferior to Comparative Examples 1 and 2 in which an organic porous film is not formed, high activity is maintained even after the accelerated deterioration test. On the other hand, the conventional catalysts of Comparative Examples 1 and 2 are slightly better in initial activity than the present invention,
After the accelerated deterioration test, the activity decreases until almost no activity occurs.

The above result can be easily inferred from the measurement result of the alkali concentration contained in the catalyst after the accelerated deterioration test.
That is, while a large amount of calcium or sodium was detected from the conventional catalyst, it was hardly detected from the catalyst according to the present invention. From this, the catalyst of the present invention has a water-repellent function due to the organic porous film formed on the surface, inhibits the entry of deliquescent calcium chloride and sodium sulfate into the catalyst, and reduces the activity. It can be seen that it is prevented.

[0030]

According to the catalyst for decomposing a halogen-containing organic compound of the present invention, the purification of a halogen-containing organic compound in an exhaust gas containing an alkali metal, an alkaline earth metal or the like can be performed.
It is possible to prevent a decrease in the activity of the catalyst due to the deliquescence of the alkali salts, and it is possible to maintain a high activity for a long time without maintaining the catalyst layer at a high temperature when the apparatus is stopped. Further, by using the halogen-containing organic compound decomposition catalyst of the present invention, it is possible to purify dioxins, which are harmful substances discharged from refuse incineration facilities, at a high decomposition rate for a long period of time.

Continued on the front page (51) Int.Cl. ⁷ Identification symbol FI Theme coat II (Reference) B01J 23/30 B01J 23/34 A 23/34 23/40 A 23/40 23/70 A 23/648 B01D 53/36 ZABG 23/70 B01J 23/64 102A 23/847 23/84 301A F term (reference) 4D048 AA11 AB03 BA03Y BA06X BA06Y BA07X BA07Y BA08Y BA23X BA23Y BA25Y BA26X BA26Y BA27X BA28X BA28Y BA30X BA35X BA35Y BA36B BB38 BC01 AA01 AA08 AA11 BA01A BA02A BA04A BA05A BA22A BA22B BB04A BC31A BC54A BC58A BC59A BC60A BC62A BC66A BC67A BC68A BC70A BC71A BC72A BC74A BC75A CA02 CA10 CA19 EA08 EB10 ED01 EE01 EE02

Claims (7)

[Claims] An organic porous component film, a mixed film of an organic porous component and inorganic oxide particles, or a mixture of an organic porous component and a catalyst component particle on a surface of a component having a function of oxidizing and decomposing a halogen-containing organic compound. A catalyst for decomposing a halogen-containing organic compound, which has a film formed thereon. 2. The catalyst according to claim 1, wherein the catalyst comprises Ti, Zr, Si and A.
l, at least one metal oxide, V, Mo and W
The halogen-containing organic compound decomposition catalyst according to claim 1, comprising at least one metal oxide of the following. 3. The catalyst according to claim 1, wherein Pt, P
The halogen-containing organic compound decomposition catalyst according to claim 1, further comprising at least one noble metal component of d, Ru, Rh, and Ir. 4. The catalyst according to claim 1, wherein the active component is Cr or M.
The halogen-containing organic compound decomposition catalyst according to claim 1, further comprising at least one transition metal component of n, Fe, Co, Ni, and Cu. 5. The halogen-containing organic compound decomposition catalyst according to claim 1, wherein the organic porous component contains at least one of a fluororesin, an acrylic resin, a polyamide resin, and a silicone resin. . 6. A halogen-containing organic compound comprising at least one slurry or emulsion selected from the group consisting of an organic porous component, a mixture of an organic porous component and inorganic oxide particles, and a mixture of an organic porous component and a catalyst component particles. A method for producing a halogen-containing organic compound decomposition catalyst, which is applied to the surface of a compound decomposition catalyst and then dried to form a porous film. 7. An exhaust gas treatment method, comprising contacting an exhaust gas containing a deliquescent component with the catalyst according to claim 1 at a temperature of 120 to 350 ° C. to decompose the halogen-containing organic compound.