JP2002224514A - Catalyst filter - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a catalyst filter capable of further efficiently removing a very small amount of a harmful substance such as dioxins or the like and dust containing the same by a compact structure. SOLUTION: The catalyst filter is adapted so as to remove dust in exhaust gas and formed from a catalytically active component for treating exhaust gas.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a catalyst filter capable of efficiently removing trace harmful substances such as dioxins contained in exhaust gas and dust.

[0002]

2. Description of the Related Art Hazardous substances such as carbon monoxide, volatile organic compounds (VOCs), dioxins, and nitrogen oxides emitted from waste incinerators, boilers, diesel engines, gas engines, and various types of industrial waste incinerators are known. Processing currently includes
Catalytic decomposition and absorption methods are used. The catalytic decomposition method is one of the most effective techniques for treating exhaust gas, and can efficiently decompose and remove gaseous harmful substances. Further, dust is also contained in the exhaust gas, and is removed by using a dust collector such as an electric dust collector, a cyclone, a ceramic filter, and a bag filter. That is, at present, the treatment of exhaust gas is performed by a system combining a catalytic reactor and a dust collector. For example, when treating exhaust gas containing dioxins, besides gaseous dioxins, depending on the conditions, there may be some that exist in a solid state or those that adhere to dust in the exhaust gas, and these may be decomposed and removed by the catalyst. Can not. Therefore, at present, the treatment is performed by combining a catalytic reaction device and a dust collecting device.

[0003]

However, the use of a dust collector and a catalytic reactor has the disadvantage that the equipment becomes large-scale. Therefore, an object of the present invention is to provide a catalytic filter capable of removing trace harmful substances such as dioxins and dust containing them in a compact device more efficiently.

[0004]

Means for Solving the Problems To solve the above problems, a catalyst filter of the present invention is a filter for removing dust from exhaust gas, and is formed of a catalytically active component for treating exhaust gas. Features.

[0005]

BEST MODE FOR CARRYING OUT THE INVENTION The catalytic filter of the present invention is a filter for removing dust from exhaust gas, and is formed of a catalytically active component for treating exhaust gas. Here, "the filter is formed of a catalytically active component" refers to a case where a portion functioning as a filter and a portion functioning as a catalyst are present separately, such as when a catalyst is carried on the filter. Rather, the filter itself is formed of a catalytically active component, and the portion that functions as a filter also functions as a catalyst at the same time. Of course, it is not intended to exclude that the catalyst filter of the present invention further supports a catalyst.

[0006] The composition of the catalyst filter of the present invention is not particularly limited as long as it is a catalytically active component as an exhaust gas treatment catalyst. The catalyst filter of the present invention is preferably formed of a catalytically active component as a catalyst for removing an organic halogen compound, particularly, V, W, Mo, Ti, Si, Pt, Pd, Mn, Cu, Cr
It is desirable to contain two or more elements selected from metals or oxides thereof. The shape of the catalyst filter of the present invention is not particularly limited, and a shape such as a honeycomb shape or a cylindrical shape having a large filtration area and a small pressure loss is preferable. As the structure of the catalyst filter of the present invention, for example,
A wall-flow type catalyst in which both ends of a honeycomb-type catalyst are plugged in a houndstooth check pattern may be used. The average pore size of the catalyst filter is preferably 1 to 50 μm. If the average pore diameter is smaller than 1 μm, the pressure loss increases, which is not preferable. The compressive strength in the flow direction of the catalyst filter is desirably 5 kgf / cm ² or more because it is necessary to withstand the pressure loss applied to the filter and the pressure during backwashing.

The thickness of the catalyst filter of the present invention is 0.5 to 2
mm, more preferably 0.8 to
1.2 mm. If the wall thickness is smaller than 0.5 mm,
It is not preferable because the mechanical strength of the filter is lowered. If the thickness is more than 2 mm, the pressure loss becomes too large, which is not preferable. Further, the aperture is preferably 3.5 to 10 mm, more preferably 4 to 6 mm. If the openings are too small, blockage due to dust tends to occur, which is not preferable. Conversely, if the aperture is too large, the filtration area will be small,
The required filter amount becomes too large, which is not preferable. Further, in the present invention, the average pore diameter is 0.5 to 0.5 by coating the partition wall surface on the inlet side of the catalyst filter with ceramic.
A 10 μm filter section can also be formed. By adopting such a two-layer structure, dust removal performance can be improved while maintaining a low pressure loss, and the mechanical strength of the catalyst filter can be increased. Further, by providing the filter portion, the contact between the catalyst portion and the dust is suppressed, the catalyst is less likely to be deteriorated by the poisoning substance contained in the dust, and the durability is improved. The ceramic material used for the filter portion is preferably a low thermal expansion ceramic such as cordierite, mullite, silicon carbide, aluminum titanate, silicate, and titanium oxide. The average pore diameter of the filter portion is preferably 0.5 to 10 μm. Average pore size is 0.5μm
If it is smaller, the pressure loss increases, which is not preferable.
When the average particle size is larger than 10 μm, the dust removal efficiency of fine particles of about 0.1 μm is not preferable. It is preferable that the thickness of the filter part is 0.01 to 1 mm.

[0008] The method for producing the catalyst filter of the present invention is not particularly limited, but a simple method of kneading, extruding, and firing using titanium oxide or a composite oxide containing titanium oxide as a raw material is simple. In this case, it is preferable to adjust the average particle diameter of the titanium oxide or the composite oxide particle containing the titanium oxide to 1 to 500 μm. More preferably, it is 5-200 μm. When the average particle diameter is less than 1 μm, the average pore diameter becomes small and the pressure loss increases, which is not preferable. When it exceeds 500 μm, the average pore diameter becomes large and the dust removal efficiency is unfavorably reduced. When a catalytically active component such as vanadium, tungsten, or molybdenum is added, it may be added as a solution during kneading, or may be impregnated and supported after extrusion and firing.

[0009] The firing temperature is preferably 300 ° C to 800 ° C. If the sintering temperature is lower than 300 ° C., the catalyst filter has poor heat resistance, and if it exceeds 800 ° C., the catalyst causes remarkable sintering. During kneading and extrusion, various binders, glass fibers, and pore-forming agents may be used.
As a binder, starch, methylcellulose, titania sol, silica sol, etc., as a pore-forming agent graphite,
A phenol resin, polyurethane, or the like can be used. Further, a titanium oxide or a composite oxide particle containing titanium oxide having an average particle diameter of 1 to 500 μm is added with a crosslinking agent for crosslinking these particles, and after kneading and extrusion molding, the crosslinking agent has a surface By carrying out the calcination in the range from the temperature at which movement begins to the temperature at which the phase transition occurs, the strength of the catalytic filter is significantly improved. Examples of the crosslinking agent include talc, kaolin, perlite, montmorillonite, cordierite, mullite, lithium aluminum, silicate, aluminum titanate, silicon carbide, alumina, titania, zirconia, or a mixture thereof, or a precursor of each of the above-described substances or a precursor thereof. And the like. Among these, cordierite or a precursor thereof is preferable in view of filter strength and moldability. When these are added, the amount is 90% of the catalyst filter weight.
% By weight or less. If the content is more than 90% by weight, the proportion of the catalyst is so small that sufficient catalytic performance cannot be obtained. As described above, when a catalytically active component such as vanadium, tungsten, or molybdenum is added, it may be added as a solution at the time of kneading, may be extruded, and may be impregnated and supported after firing, but a cross-linking agent having a high phase transition temperature is used. In this case, in order to prevent sintering of the catalytically active component, it is preferable to carry out the impregnation after extrusion and firing.

When performing exhaust gas treatment using the catalyst filter of the present invention, the treatment temperature is preferably 130 to 650 ° C.,
180-450 ° C is more preferred. If the temperature is lower than 130 ° C., it is not preferable because the decomposition efficiency of the organic halogen compound is reduced. The gas linear velocity with respect to the catalyst filter surface is 0.01 to 5
Nm / min is preferable, and 0.05 to 2 Nm / min is more preferable. If the gas linear velocity is low, the dust removal efficiency is low, and if the gas linear velocity is too high, the pressure loss increases. The catalyst filter of the present invention, in addition to the treatment of organic halogen compound-containing exhaust gas,
By appropriately selecting the active component, it can be used for the treatment of carbon monoxide, the treatment of volatile organic compounds (VOC), and the treatment for removing nitrogen oxides by injecting ammonia from the upstream side of the filter.

When the catalyst filter of the present invention is deteriorated by long-term use, it can be regenerated by washing or heating. Since the catalytic filter of the present invention can decompose and remove gaseous dioxins on the catalyst and capture solid dioxins contained in dust and dust, the dust filter and the catalytic reactor are used. This has the advantage that the device is more compact than in the case. Conversely, using the catalyst filter of the present invention as a dust collector,
Alternatively, by using the catalyst filter of the present invention as a catalyst reactor, dioxins and the like can be removed with higher efficiency as compared with a case where a normal dust collector and a normal catalyst reactor are used in combination.

[0012]

The present invention will be described in more detail with reference to the following Examples, but it should not be construed that the invention is limited thereto.
[Example 1] A Ti-Si composite oxide powder was prepared by the method described below. SNOWTEX -20 to 10 wt% ammonia liquid 700 liters (manufactured by Nissan Chemical silica sol, about 20 wt% -SiO ₂ containing) 21.3 kg was added, followed by stirring and mixing, 125 g / liter as sulfuric acid solution (TiO ₂ titanyl sulfate , Sulfuric acid concentration 550g / l) 3
Forty liters were gradually added dropwise with stirring. After leaving the obtained gel for 3 hours, the gel was filtered and washed with water.
Dried for 0 hours. Next, the powder was fired at 550 ° C. and pulverized to obtain a powder having an average particle diameter of 80 μm. The composition of the obtained Ti—Si composite oxide powder was TiO ₂ : SiO ₂ = 8.5: 1.
5 (molar ratio).

To 20 kg of the powder, a chemical solution prepared by dissolving 2.0 kg of ammonium metavanadate, 1.4 kg of ammonium paramolybdate tetrahydrate, 2.4 kg of oxalic acid and 1.0 kg of monoethanolamine in 12 liters of water was added. Further, 1 kg of phenol resin and 0.5 kg of starch are added and mixed, kneaded with a kneader, and then extruded with an extruder to have an outer shape of 150 mm square, 5.0 mm opening, and 1.0 m wall thickness.
m, and formed into a honeycomb shape having a length of 500 mm. Then 1
After drying at 20 ° C., both ends were plugged with a kneaded material of the same catalyst component in a staggered lattice pattern, and dried again at 120 ° C. 4
It was calcined at 50 ° C. for 5 hours in an air atmosphere to obtain a wall flow type catalyst filter. The composition of the catalyst filter thus obtained was V ₂ O ₅ : MoO ₃ : TiO ₂ : SiO ₂ =
7: 5: 78: 10 (weight ratio). The average pore diameter is 20 μm, and the compressive strength in the flow channel direction is 25 kgf / cm.
^{Was 2} .

Example 2 Ti—S prepared in Example 1
i Composite oxide powder 20 kg and a crosslinking agent (talc 750 g,
1 kg of phenolic resin, 1.0 kg of starch and about 13 liters of water were added to a mixture of 950 g of kaolin and 300 g of alumina, mixed and kneaded with a kneader, and then extruded with a 150 mm square, 5.0 mm mesh with an extruder. Thickness 1.
It was formed into a honeycomb shape having a length of 0 mm and a length of 500 mm. Next, after drying at 200 ° C., both ends were plugged with a kneaded product of the same components, and dried at 200 ° C. again. 5 at 1360 ° C
Calcination was performed in an air atmosphere for hours to obtain a catalyst filter. Further, a mixed solution of a compound of vanadium and molybdenum is impregnated and fired, and a weight ratio of V ₂ O ₅ : MoO ₃ : TiO ₂ : SiO ₂ : crosslinking agent = 5: 4: 73: 9.6: 8.3 is obtained. A wall-flow type catalytic filter was obtained. This catalyst filter has an average pore diameter of 22 μm and a compressive strength of 80 in the flow channel direction.
kgf / cm ² .

[Embodiment 3] Ti-Si described in Embodiment 1
Composite oxide powder having average particle diameter of 8 μm 1
kg and 0.1 kg (in terms of solid oxide) of the gel after filtration and water washing obtained in the preparation process are dispersed in 20 liters of water to form a slurry, and the slurry is applied to the inlet-side partition surface of the catalyst filter prepared in Example 1 for 1 minute. Soaked. Excess slurry was removed, dried and then fired at 500 ° C. In this way, about 0.1 mm thick Ti-S
An i composite oxide filter film was formed. The pore size of the filter was 1-2 μm.

[Exhaust gas treatment performance test] The exhaust gas treatment performance of the catalyst filters prepared in Examples 1 to 3 was measured using incinerator exhaust gas. The test conditions are as follows. Table 1 shows the results. (Test conditions) Treated exhaust gas characteristics O ₂ : 10%, H ₂ O: 15%, dust: 40 mg / Nm ³ Gas temperature: 265 ° C. Gas linear velocity on the filter surface: 0.13 m / min Space velocity: 5800 h ⁻¹

[0017]

[Table 1]

[0018]

According to the catalyst filter of the present invention, gaseous dioxins can be decomposed and removed on a catalyst with a compact device, and dioxins contained in solid and dust can be captured by the filter. . Therefore,
Trace harmful substances such as dioxins and dust containing them can be efficiently removed.

 ────────────────────────────────────────────────── ─── Continued on the front page (72) Inventor Nobuyuki Masaki 992, Nishioki, Okihama-shi, Aboshi-ku, Himeji-shi, Hyogo Japan Nippon Shokubai Co., Ltd. F-term in Nippon Shokubai F-term (reference) 4D019 AA01 BA05 BA06 BB06 BC07 CA01 CA03 4D048 AA11 BA06X BA07X BA10Y BA23X BA26X BA42X BB02 BB14 BB17 CC41 CD05 4G069 AA03 AA11 BA02A BA02B BA04A BA04B BA20A BB20BA BCBC BC75A CA11 CA19 EA06 EA18 EA19 EA27 EB14Y EB15Y EC17Y

Claims (3)

[Claims] 1. A catalyst filter for removing dust from an exhaust gas, wherein the filter is formed of a catalytically active component for treating the exhaust gas. 2. The catalytic filter according to claim 1, wherein the catalytic filter is formed of a catalytically active component as a catalyst for removing an organic halogen compound. 3. The catalytic filter according to claim 1, wherein the catalytic filter is a wall flow type.