JP2003200046A - Catalyst for waste gas treatment and method for treating waste gas - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To obtain a catalyst for waste gas treatment excellent in nitrogen oxides removing performance, in removing performance of organic halogen compounds such as dioxins in the waste gas and in durability, and to provide a method for treating the waste gas by using the same. <P>SOLUTION: The catalyst for the waste gas treatment contains titanium, molybdenum and vanadium oxides and is characterized by having a peak at 2θ=27.3° in an X-ray diffraction pattern and containing molybdenum oxide particles with ≥1 μm and ≤20 μm particle diameters. <P>COPYRIGHT: (C)2003,JPO

Description

Detailed Description of the Invention

[0001]

TECHNICAL FIELD The present invention relates to an exhaust gas treatment catalyst and an exhaust gas treatment method. Particularly, a catalyst for exhaust gas treatment excellent as a denitration catalyst for removing nitrogen oxides (NOx) in exhaust gas and a catalyst for removing organic halogen compounds for removing toxic organic halogen compounds such as dioxins in exhaust gas. And a method for treating exhaust gas using the same.

[0002]

2. Description of the Related Art As a method for removing nitrogen oxides from exhaust gas, which is currently in practical use, harmless nitrogen is obtained by catalytically reducing nitrogen oxides in exhaust gas using a reducing agent such as ammonia or urea on a denitration catalyst. The so-called SCR method, which is a selective catalytic reduction that decomposes into water and water, is common. In recent years, as environmental pollution caused by nitrogen oxides, as represented by acid rain, has become serious worldwide, it is required to improve the efficiency of denitration technology. Under such circumstances, a denitration catalyst composed of oxides of titanium and vanadium and oxides of molybdenum and tungsten (Japanese Patent Publication No. 53-28148), binary oxides composed of titanium and silicon, vanadium and tungsten. , A denitration catalyst comprising a metal oxide such as molybdenum (Japanese Patent Publication No. 57-30532) has been put into practical use.
Currently widely used.

Dioxins and P are contained in the exhaust gas generated from incineration facilities for treating industrial waste and municipal waste.
It contains a very small amount of toxic organic halogen compounds such as CB and chlorophenol. Especially, even dioxins in a very small amount are extremely toxic and seriously affect the human body. ing. The catalytic decomposition method is one of the most effective techniques, and generally, a catalyst containing an oxide such as titanium, vanadium, tungsten, or molybdenum is used. Among the various exhaust gas treatment catalysts that have been used so far, catalysts containing titanium oxides and vanadium oxides are mentioned as having relatively high performance. Recently, molybdenum oxides have been added to these oxides. A catalyst in which tungsten oxide or tungsten oxide is highly dispersed to form a composite oxide has been reported (Japanese Patent Laid-Open No. 2001-2).
86729 and JP 2001-286733 A). By thus highly dispersing molybdenum oxide or tungsten oxide in the form of a composite oxide, the poisoning deterioration of titanium oxide and vanadium oxide due to SO _{2 in} exhaust gas, which has been a problem in the past, is a problem. It has been reported that, while being suppressed, it is also possible to suppress the decrease in the catalytic activity originally possessed by titanium oxide and vanadium oxide.

However, even with these catalysts,
Depending on exhaust gas conditions, sufficient performance cannot be exhibited, and further catalytic performance, in particular, removal performance of nitrogen oxides, removal performance of organic halogen compounds such as dioxins in exhaust gas, and improvement of durability are desired.

[0005]

Therefore, an object of the present invention is to provide a catalyst for exhaust gas treatment, which is excellent in nitrogen oxide removal performance, organic halogen compound removal performance such as dioxins in exhaust gas, and durability. , It is to provide an exhaust gas treatment method using the same.

[0006]

Means for Solving the Problems The inventors of the present invention have made extensive studies to solve the above problems. As a result, focusing on the X-ray diffraction pattern in the catalyst containing oxides of titanium, molybdenum, and vanadium, it was found that a catalyst showing a specific peak can solve the above problems. Further, by paying attention to the particle size of molybdenum oxide in the catalyst containing oxides of titanium, molybdenum, and vanadium, the catalyst is prepared so as to contain molybdenum oxide particles in a certain particle size range. , It has been found that the above problems can be solved.

That is, the exhaust gas treating catalyst according to the present invention is a catalyst containing oxides of titanium, molybdenum and vanadium, and has a peak at 2θ = 27.3 ° in the X-ray diffraction pattern. Characterize.
Another exhaust gas treatment catalyst according to the present invention is a catalyst containing oxides of titanium, molybdenum, and vanadium, and contains molybdenum oxide particles having a particle diameter of 1 μm or more and 20 μm or less. Characterize.
Furthermore, the exhaust gas treatment method according to the present invention is characterized by treating exhaust gas containing nitrogen oxides using the catalyst of the present invention.

The exhaust gas treatment method according to the present invention is
An exhaust gas containing an organic halogen compound is treated using the catalyst of the present invention.

[0009]

BEST MODE FOR CARRYING OUT THE INVENTION The exhaust gas treating catalyst of the present invention contains titanium oxide as the main component of the catalyst component. The titanium oxide may be a general titanium oxide (titanium oxide (TiO ₂ ) or the like) or a titanium-silicon composite oxide (hereinafter referred to as Ti—Si composite oxide). Moreover, you may use these together. As the titanium oxide feed material, in addition to titanium oxide (TiO ₂ ), any inorganic or organic compound can be used as long as it is capable of firing to produce titanium oxide. For example, an inorganic titanium compound such as titanium tetrachloride or titanium sulfate or an organic titanium compound such as titanium oxalate or tetraisopropyl titanate can be used.

As the titanium source used for the preparation of the above Ti-Si composite oxide, any of the above-mentioned inorganic and organic compounds can be used, and as the silicon source, colloidal silica, water glass, fine particle silicon. , An inorganic silicon compound such as silicon tetrachloride and an organic silicon compound such as tetraethyl silicate can be appropriately selected and used. The Ti-Si composite oxide can be prepared, for example, by the following procedures (a) to (d). (A) Silica sol and ammonia water are mixed, a sulfuric acid aqueous solution of titanium sulfate is added to cause precipitation, the obtained precipitate is washed and dried, and then calcined at 300 to 700 ° C. (B) An aqueous solution of sodium silicate is added to an aqueous solution of titanium sulfate to cause a reaction to generate a precipitate, the obtained precipitate is washed and dried, and then calcined at 300 to 700 ° C. (C) Ethyl silicate (tetraethoxysilane) was added to a water-alcohol solution of titanium tetrachloride and then hydrolyzed to generate a precipitate, which was washed and dried, and then 300 to 700 ° C. Bake at. (D) Ammonia is added to a water-alcohol solution of titanium oxide chloride (titanium oxytrichloride) and ethyl silicate to cause precipitation, and the resulting precipitate is washed and dried,
Then, it is baked at 300 to 700 ° C.

Among the above methods, the method (a) is particularly preferable, and more specifically, a silicon source and ammonia water are taken in a predetermined molar ratio to prepare an acidic aqueous solution or sol state as a titanium source. (1 to 100 g / liter (the titanium source is converted to TiO ₂ ) in an acidic aqueous solution or sol state), while maintaining the temperature at 10 to 100 ° C.,
A coprecipitate of titanium and silicon is formed by maintaining the pH of 2 to 10 for 10 minutes to 3 hours, the precipitate is filtered, thoroughly washed, and then dried at 80 to 140 ° C. for 10 minutes to 3 hours, and 300 to By firing at 700 ° C. for 1 to 10 hours, the target Ti—Si composite oxide can be obtained.

The exhaust gas treating catalyst of the present invention contains vanadium oxide as an auxiliary component. The content of vanadium oxide is the oxide of titanium (titanium oxide,
Ti-Si composite oxide, or titanium oxide and Ti
-Si complex oxide total) is preferably 0.1 to
It is 25% by weight, more preferably 1 to 15% by weight. If the vanadium oxide content is less than 0.1% by weight, the effect of addition is not sufficiently obtained, while if it exceeds 25% by weight, the activity is not significantly improved, and in some cases, the activity decreases. It is also not preferable because it is also present. The exhaust gas treatment catalyst of the present invention contains molybdenum oxide as an auxiliary component. The content of molybdenum oxide is preferably 0. 0 with respect to the titanium oxide as the main component (titanium oxide, Ti-Si composite oxide, or the total of titanium oxide and Ti-Si composite oxide). 1 to 25% by weight, more preferably 0.1 to 20% by weight, still more preferably 0.5.
-15% by weight, particularly preferably 1-15% by weight.
When the content of molybdenum oxide is less than 0.1% by weight, the effect of addition is not sufficiently obtained. On the other hand, when it exceeds 25% by weight, the activity is not significantly improved, and in some cases, the activity decreases. It is also not preferable because it is also present.

As the feed material for vanadium oxide and molybdenum oxide, in addition to the respective oxides themselves, both inorganic and organic compounds can be used as long as they produce these oxides by firing. it can. For example, hydroxides, ammonium salts, oxalates, halides, sulfates, nitrates containing each metal can be used. The exhaust gas treatment catalyst according to the present invention is a catalyst containing oxides of titanium, molybdenum, and vanadium, and 2θ = 2 in the X-ray diffraction pattern.
It is characterized by having a peak at 7.3 °.

2θ = 27.3 in X-ray diffraction pattern
The peak of ° is one of a group of peaks given by molybdenum oxide, and when the X-ray diffraction pattern of the molybdenum oxide crystal is measured, one of the peaks appears at 2θ = 27.3 °. When there is no peak at 2θ = 27.3 ° in the X-ray diffraction pattern, the molybdenum oxide is highly dispersed in the titanium oxide. Furthermore, 2
The peak intensity at θ = 27.3 ° is 1 of the peak intensity at 2θ = 25.3 °, which is one of the peaks of anatase type titanium.
When it is less than%, it can be judged that the molybdenum oxide is sufficiently dispersed in the titanium oxide.

As described above, by highly dispersing molybdenum oxide or the like in the form of a composite oxide, titanium oxide or vanadium oxide due to SO _{2 in} exhaust gas, which has been a problem in the past, has been a problem. It is possible to suppress the poisoning deterioration of titanium oxide and also suppress the reduction of the catalytic activity originally possessed by titanium oxide and vanadium oxide. As described above, it is confirmed that molybdenum oxide is highly dispersed. It is disclosed in Japanese Patent Laid-Open No. 2001-2867
No. 29, JP 2001-286733 A, and the like. The inventor of the present invention, regarding molybdenum oxide, which is conventionally considered to be used in a highly dispersed state to contribute to performance improvement, is different from the conventional idea in that it is used in a state of moderately aggregated crystalline molybdenum oxide. investigated. As a result, they have found that they are excellent in the removal performance of nitrogen oxides, the removal performance of organic halogen compounds such as dioxins in exhaust gas, and the durability. Then, when the X-ray diffraction pattern has a peak at 2θ = 27.3 °, it was found that the molybdenum oxide was present in the crystalline state in which the molybdenum oxide was appropriately aggregated in the titanium oxide. .

Further, in order for molybdenum oxide to exist in a more appropriately aggregated crystalline state, 2θ = 2
The peak intensity at 7.3 ° is preferably 1% or more and 50% or less of the peak intensity at 2θ = 25.3 °, which is one of the peaks of anatase titanium. When the peak intensity at 2θ = 27.3 ° is less than 1% of the peak intensity at 2θ = 25.3 °, which is one of the anatase-type titanium peaks, the crystallinity of molybdenum oxide is insufficient. Because there is
The effect of the present invention may not be exhibited. Also, 2θ
= 27.3 ° is 50% of the peak intensity of 2θ = 25.3 °, which is one of the peaks of anatase titanium.
When it is more than%, the molybdenum is extremely agglomerated and the specific surface area of the crystalline molybdenum particles is reduced, so that the effect of the invention cannot be exhibited, which is not preferable.

In the exhaust gas treatment catalyst of the present invention, as described above, it is important that the molybdenum oxide is present in the crystalline state in which the molybdenum oxide is appropriately aggregated in the titanium oxide. Focusing on another aspect, that is, the particle diameter of molybdenum oxide, the present invention has been completed as the state of containing molybdenum oxide particles having a certain particle diameter range. That is, the exhaust gas treatment catalyst of the present invention is a catalyst containing oxides of titanium, molybdenum, and vanadium, and is characterized by containing molybdenum oxide particles having a particle diameter of 1 μm or more and 20 μm or less. .
The particle diameter is preferably 1 μm or more and 18 μm or less, more preferably 1 μm or more and 15 μm or less.

Further, in order for the molybdenum oxide to exist in a more appropriately agglomerated state, the particle diameter is 1 μm or more 2
The proportion of molybdenum oxide particles having a particle diameter of 0 μm or less is preferably 1% or more and 30% or less, and more preferably 1% or more and 25% or less. The method of analyzing the state of particles as described above is not particularly limited, but examples thereof include EPMA and SEM-EDS. The EPMA analysis will be described below as an example. EP on catalyst surface
The MA analysis is an analysis for observing the state of the catalyst composition component in the catalyst to be analyzed, and is performed by the same analysis method as the EPMA analysis generally performed. When analyzing the state of the catalyst by EPMA analysis, for example, a method in which a small amount of an arbitrary catalyst surface is cut out is used as a measurement sample, and a specific portion of this measurement sample is measured, or when the catalyst is small, the measurement is performed as it is. Examples include the method of using as a sample,
There is no particular limitation. The exhaust gas treating catalyst according to the present invention can be specified by EPMA analysis when the measured surface area of the catalyst is 380 μm ² . Of course, this measurement area may be appropriately adjusted depending on the conditions.

The above molybdenum particle size and its ratio are
It was calculated from the number average measured from the EPMA chart. If the above range is not satisfied, the effect of the present invention cannot be sufficiently achieved, which is not preferable. Generally, the state observed on any part of the catalyst surface can be regarded as directly reflecting the state of the entire catalyst. For example, when the catalyst surface is subjected to EPMA analysis with a measurement area of 380 μm ² , the particle diameter is 1 μm. When the proportion of molybdenum oxide having a thickness of 20 μm or less in the measured area is 1% or more and 30% or less, it can be inferred that the entire catalyst is in the same state. In addition, you may average the measurement result of arbitrary several places. Therefore, in the exhaust gas treating catalyst of the present invention, for example, the measurement surface of the catalyst surface is 380 μm ²
In EPMA analysis, the particle size is 1μm or more and 20μ
The molybdenum oxide particles having a particle size of m or less are observed, and the proportion of the molybdenum oxide having a particle diameter of 1 μm or more and 20 μm or less in the measurement area is from 1% to 30%
The following means the state over the entire catalyst.

The particle diameter in the present invention means the diameter in the case of spherical particles, but means the longest diameter when it does not have a constant diameter (when it is not spherical).
The shape of the catalyst of the present invention is not particularly limited, and a plate shape,
It may be used in a desired shape selected from a corrugated plate shape, a net shape, a honeycomb shape, a columnar shape, a cylindrical shape, etc., and alumina,
Plates, corrugated plates, nets, honeycombs, columns made of silica, cordierite, titania, stainless metal, etc.
It may be used by being carried on a carrier having a desired shape selected from a cylindrical shape and the like. The catalyst of the present invention can be prepared by any method. One example thereof will be shown below, but the method for preparing the catalyst of the present invention is not limited thereto.

As the method for preparing the catalyst of the present invention, for example, powder of titanium oxide as a main component, powder of vanadium oxide and molybdenum oxide, salts, or a solution thereof may be used in any order. The method of adding and preparing can be mentioned. Alternatively, a method may be used in which powders of vanadium oxide and molybdenum oxide, salts, or a solution thereof are mixed in advance and then added to the powder of titanium oxide which is the main component. In the molded body of
A method of impregnating and supporting a solution of salts of vanadium oxide and molybdenum oxide or a mixture of both of them may be used. As another method for preparing the catalyst of the present invention, for example,
A method of supporting molybdenum oxide on a mixture of titanium oxide and vanadium oxide as the main component, and a method of supporting vanadium oxide on a mixture of titanium oxide and molybdenum oxide as the main component be able to.

When the titanium oxide and the Ti-Si composite oxide are mixed, a conventionally known mixing method may be used. For example, a titanium oxide powder and the Ti-Si composite oxide are mixed in a mixer such as a kneader. It is possible to add the product powder and stir and mix. The exhaust gas treating catalyst of the present invention is used for treating various exhaust gases. There is no particular limitation on the composition of the exhaust gas, the catalyst of the present invention, boiler, incinerator,
Since it is excellent in the decomposition activity of nitrogen oxides discharged from gas turbines, diesel engines and various industrial processes, it is suitably used for treating exhaust gas containing these nitrogen oxides. In order to carry out denitration using the catalyst of the present invention, the catalyst of the present invention is brought into contact with exhaust gas in the presence of a reducing agent such as ammonia or urea to reduce and remove nitrogen oxides in the exhaust gas. The conditions at this time are not particularly limited, and the conditions generally used for this type of reaction can be used. Specifically, it may be appropriately determined in consideration of the type and properties of exhaust gas, the required decomposition rate of nitrogen oxides, and the like.

When performing denitration using the catalyst of the present invention, the space velocity of exhaust gas is usually 100 to 100,000.
Hr ^-1 (STP), preferably 200 to 5000
It is 0 Hr ^-1 (STP). If it is less than 100 Hr ^-1 , the processing equipment becomes too large, resulting in inefficiency.
If it exceeds 0000 Hr ^-1 , the decomposition efficiency decreases. Also,
The temperature at that time is preferably 100 to 500 ° C, and more preferably 150 to 400 ° C. The catalyst of the present invention is also suitably used for treating exhaust gas containing an organic halogen compound, which is generated from an incineration facility for treating industrial waste or municipal waste.

In order to treat the organohalogen compound with the catalyst of the present invention, the catalyst of the present invention is brought into contact with exhaust gas to decompose and remove the organohalogen compound in the exhaust gas. The conditions at this time are not particularly limited, and the conditions generally used for this type of reaction can be used. Specifically, it may be appropriately determined in consideration of the type and properties of the exhaust gas, the required decomposition rate of the organic halogen compound, and the like. It is also possible to denitrate at the same time by adding a reducing agent such as ammonia or urea. The space velocity of the exhaust gas when treating the organic halogen compound using the catalyst of the present invention is usually 100 to 100,000 Hr.
^-1 (STP), preferably 200 to 50000H
r ⁻¹ (STP). If it is less than 100 Hr ^-1 , the processing equipment becomes too large, resulting in inefficiency.
If it exceeds 00 Hr ^-1 , the decomposition efficiency decreases. The temperature at that time is preferably 130 to 500 ° C.,
More preferably, it is 150 to 400 ° C.

[0025]

EXAMPLES The present invention will be described in more detail with reference to Examples and Comparative Examples, but the present invention is not limited to the following Examples. (XRD measurement) X-ray diffraction pattern measurement, that is, XRD
The measurement was performed using an X-ray diffractometer (Rigaku RU-300). (EPMA analysis) The EPMA analysis is based on Shimadzu E Co., Ltd.
An X-ray image of MoLα was magnified at a magnification of 4000 using PMA-1610 under the conditions of a weighted voltage of 15 kV and a sample current of 50 nA.
Measured in double.

Example 1 Commercially available titanium oxide powder (DT
-51 (trade name), manufactured by Millennium Co., Ltd.) 20 kg, ammonium metavanadate 1.47 kg, oxalic acid 1.8
Kg, a solution of 0.4 kg of monoethanolamine dissolved in 5 liters of water, and molybdenum trioxide powder 1.
After adding 59 kg, the mixture was mixed with a molding aid, kneaded with a kneader, and then molded into a honeycomb shape by an extrusion molding machine. The obtained molded product was dried at 60 ° C. and then 530 in an air atmosphere.
The target catalyst (1) was obtained by calcination for 5 hours. The composition at this time was TiO ₂ : MoO ₃ : V _{2 in} terms of oxide conversion weight ratio.
O ₅ = 88: 7: 5.

When the catalyst (1) was analyzed by an X-ray diffractometer, as shown in FIG. 1 and its enlarged view,
A peak was observed at 2θ = 27.3 °. Also, 2θ =
The peak intensity at 27.3 ° was 2% of the peak intensity at 2θ = 25.3 °, which is one of the anatase-type titanium peaks. Furthermore, the measurement area of the catalyst surface of the catalyst (1) is 38
When analyzed by EPMA at 0 μm ² , the proportion of molybdenum oxide having a particle diameter of 1 μm or more and 20 μm or less in the above-mentioned measurement area was 19%. EPM of catalyst (1)
An electron beam photograph taken by the A analysis is shown in FIG. The white part in FIG. 7 represents molybdenum oxide.

(Example 2) <Preparation of Ti-Si composite oxide powder> Ti-Si composite oxide powder was prepared as follows. Silica sol (Snowtex -30, manufactured by Nissan Chemical Industries, Ltd., 30wt in terms of SiO ₂
% Content) and industrial ammonia water (25 wt% N)
A uniform solution was prepared by mixing 104 kg of (containing H ₃ ) and 73 liters of water. A sulfuric acid solution of titanyl sulfate (manufactured by Teika, 70 g / liter as TiO ₂ , H ₂ S
243 liters (containing 287 g / liter as O ₄ ) were gradually added dropwise with stirring. The obtained slurry is allowed to stand for about 20 hours, then filtered and washed with water, and subsequently at 150 ° C.
And dried for 1 hour. Furthermore, in an air atmosphere, 550 ° C
Bake for 5 hours, then crush with a hammer mill,
A powder was obtained. The composition of the Ti—Si composite oxide powder thus prepared was TiO ₂ : SiO ₂ = 85: 15 (oxide weight ratio).

<Addition of vanadium oxide and molybdenum oxide> Ti-Si composite oxide powder 2 prepared above
0 kg, ammonium metavanadate 1.43 kg,
Oxalic acid 1.7 kg, monoethanolamine 0.4 kg
Was dissolved in 5 liters of water, and 1.11 kg of molybdenum trioxide powder was added, mixed with a molding aid, kneaded with a kneader, and then molded into a honeycomb shape by an extrusion molding machine. The obtained molded product was dried at 60 ° C. and then calcined at 530 ° C. for 5 hours in an air atmosphere to obtain the target catalyst (2). The composition at this time was Ti-S in terms of oxide-based weight ratio.
i complex oxide: MoO ₃ : V ₂ O ₅ = 90: 5: 5.

When the catalyst (2) was analyzed by an X-ray diffractometer, a peak was observed at 2θ = 27.3 ° as shown in FIG. Further, the peak intensity at 2θ = 27.3 ° is one of the peaks of anatase type titanium, 2θ = 2.
It was 16% of the peak intensity at 5.3 °. Further, when the catalyst surface of the catalyst (2) was analyzed by EPMA with a measurement area of 380 μm ² , the ratio of molybdenum oxide having a particle size of 1 μm or more and 20 μm or less in the measurement area was 10 μm.
%Met. An electron beam photograph taken by EPMA analysis of the catalyst (2) is shown in FIG. The white part in FIG. 8 represents molybdenum oxide.

(Example 3) Ti-S prepared in Example 2
A solution of 1.43 kg of ammonium metavanadate, 1.7 kg of oxalic acid and 0.4 kg of monoethanolamine dissolved in 5 liters of water, to 20 kg of i-composite oxide powder, 1.36 kg of ammonium paramolybdate and monoethanolamine A solution prepared by dissolving 0.54 Kg in 3 liters of water was added, mixed with a molding aid, kneaded with a kneader, and then molded into a honeycomb shape by an extruder. After drying the obtained molded product at 60 ° C., in an air atmosphere,
The target catalyst (3) was obtained by calcining at 530 ° C. for 5 hours. The composition at this time, in terms of oxide weight ratio, Ti-Si composite _{oxide: MoO 3: V 2 O 5} = 90: 5: was 5.

When the catalyst (3) was analyzed by an X-ray diffractometer, a peak was observed at 2θ = 27.3 ° as shown in FIG. Further, the peak intensity at 2θ = 27.3 ° is one of the peaks of anatase type titanium, 2θ = 2.
It was 23% of the peak intensity at 5.3 °. Furthermore, when the catalyst surface of the catalyst (3) was subjected to EPMA analysis with a measurement area of 380 μm ² , the proportion of molybdenum oxide having a particle diameter of 1 μm or more and 20 μm or less in the measurement area was 6%.
Met. An electron beam photograph taken by EPMA analysis of the catalyst (3) is shown in FIG. The white part in FIG. 9 represents molybdenum oxide.

Comparative Example 1 Commercially available titanium oxide powder (DT
-51 (trade name), manufactured by Millennium Co., Ltd.) 20 kg, ammonium metavanadate 1.43 kg, oxalic acid 1.7
Kg, a solution of 0.4 kg of monoethanolamine dissolved in 5 liters of water, 1.36 kg of ammonium paramolybdate and 0.54 kg of monoethanolamine
Was mixed with 3 liters of water, mixed with a molding aid, kneaded with a kneader, and then molded into a honeycomb shape by an extruder. The obtained molded product was dried at 60 ° C and then calcined at 350 ° C for 5 hours in an air atmosphere to obtain the target catalyst (4). The composition at this time was TiO ₂ : MoO ₃ : V ₂ O ₅ = 90: 5: 5 in terms of oxide conversion weight ratio.

When the catalyst (4) was analyzed by an X-ray diffractometer, as shown in FIG. 5, no peak was observed at 2θ = 27.3 °. Furthermore, when the catalyst surface of the catalyst (4) was subjected to EPMA analysis with a measurement area of 380 μm ² , the proportion of molybdenum oxide having a particle size of 1 μm or more and 20 μm or less in the measurement area was 0%. An electron beam photograph taken by EPMA analysis of the catalyst (4) is shown in FIG.
It shows in 0. The white part in FIG. 10 represents molybdenum oxide. (Comparative Example 2) Ammonium metavanadate 1.40 was added to 20 kg of the Ti-Si composite oxide powder prepared in Example 2.
Kg, oxalic acid 1.7 Kg, monoethanolamine 0.
A solution prepared by dissolving 4 kg in 5 liters of water and a solution prepared by dissolving 0.8 kg of ammonium paramolybdate and 0.32 kg of monoethanolamine in 3 liters of water were added, mixed with a molding aid, and kneaded with a kneader. After that, it was formed into a honeycomb shape by an extruder. The obtained molded product was dried at 60 ° C. and then calcined in an air atmosphere at 350 ° C. for 5 hours to obtain the target catalyst (5). The composition at this time, in terms of oxide weight ratio, Ti-Si composite oxide: MoO _3:
V ₂ O ₅ = 92: 3: 5.

When the catalyst (5) was analyzed by an X-ray diffractometer, no peak was observed at 2θ = 27.3 ° as shown in FIG. Further, when the catalyst surface of the catalyst (5) was subjected to EPMA analysis with a measurement area of 380 μm ² , the proportion of molybdenum oxide having a particle diameter of 1 μm or more and 20 μm or less in the measurement area was 0%. An electron beam photograph taken by EPMA analysis of the catalyst (5) is shown in FIG.
Shown in 1. The white part in FIG. 11 represents molybdenum oxide. (Denitration performance test and dioxins decomposition test) Catalysts (1) to Examples 1 to 3 and Comparative Examples 1 and 2
Using (5), a denitration performance test and a dioxin decomposition test were conducted under the following conditions.

The denitration rate and the decomposition rate of dioxins were determined according to the following formulas. Denitration rate (%) = [(reactor inlet NOx concentration)-(reactor outlet NOx concentration)] / (reactor inlet NOx concentration) x 10
0 Decomposition rate of dioxin (%) = [(reactor inlet dioxin concentration)-(reactor outlet dioxin concentration)] ÷
(Reactor inlet dioxin concentration) × 100 <Denitration reaction gas composition> NOx: 100 ppm SO ₂ : 20 ppm NH ₃ : 100 ppm O ₂ : 10% H ₂ O: 15% N ₂ : Balance gas temperature: 240 ° C. Space velocity: 19000Hr ^-1 <Dioxin decomposition reaction gas composition> Dioxin concentration: Approximately 1 ng O ₂ : 15% H ₂ O: 12% SO ₂ : 20 ppm Dust: 100 mg / Nm ³ N ₂ : Balance gas temperature: 200 ° C Space velocity: The results of the 2500 Hr ^-1 denitration performance test are shown in Table 1, and the results of the dioxins decomposition test are shown in Table 2.

[0037]

[Table 1]

[0038]

[Table 2]

[0039]

EFFECTS OF THE INVENTION According to the present invention, it is possible to provide a catalyst for exhaust gas treatment which is excellent in the removal performance of nitrogen oxides, the removal performance of organic halogen compounds such as dioxins in exhaust gas, and the durability. Therefore, when used as a denitration catalyst, the denitration performance is improved. When used as a catalyst for removing organic halogen compounds, organic halogen compounds such as dioxins in exhaust gas can be efficiently removed.

[Brief description of drawings]

FIG. 1 is an X-ray diffraction pattern diagram of the catalyst (1) prepared in Example 1.

FIG. 2 is an enlarged view of an X-ray diffraction pattern of the catalyst (1) prepared in Example 1.

FIG. 3 is an X-ray diffraction pattern diagram of the catalyst (2) prepared in Example 2.

FIG. 4 is an X-ray diffraction pattern diagram of the catalyst (3) prepared in Example 3.

FIG. 5 is an X-ray diffraction pattern diagram of the catalyst (4) prepared in Comparative Example 1.

FIG. 6 is an X-ray diffraction pattern diagram of the catalyst (5) prepared in Comparative Example 2.

FIG. 7 is an electron micrograph of the catalyst (1) prepared in Example 1 by EPMA analysis.

FIG. 8 is an electron micrograph of the catalyst (2) prepared in Example 2 by EPMA analysis.

9 is an electron micrograph of the catalyst (3) prepared in Example 3 by EPMA analysis.

FIG. 10: EPMA of catalyst (4) prepared in Comparative Example 1
Electron radiograph by analysis

11: EPMA of catalyst (5) prepared in Comparative Example 2 FIG.
Electron radiograph by analysis

   ─────────────────────────────────────────────────── ─── Continued front page    (72) Inventor Noboru Sugishima             Hyogo prefecture Himeji city             1 Within Nippon Shokubai Co., Ltd. F-term (reference) 4D048 AA06 AA11 AB01 AB03 AB07                       AC03 AC04 BA06X BA07X                       BA23X BA26X BA41X BA42X                       BB17                 4G069 AA02 AA08 BA04A BA04B                       BB04A BB04B BB06A BB06B                       BC50A BC50B BC54A BC54B                       BC59A BC59B BD05A BD05B                       CA02 CA08 CA10 CA13 CA19                       DA06 EA19 EB18X EC22X                       EC22Y EC25 EC27 FA01                       FB09 FB30 FB67                 4G072 AA37 GG03 HH18 JJ30 MM21                       MM22 MM23 MM36 UU15

Claims (5)

[Claims] 1. A catalyst for treating exhaust gas, which is a catalyst containing oxides of titanium, molybdenum, and vanadium, which has a peak at 2θ = 27.3 ° in an X-ray diffraction pattern. 2. The peak intensity at 2θ = 27.3 ° is one of the peaks of anatase type titanium, 2θ = 25.3.
It is 1% or more and 50% or less of the peak intensity of °.
The exhaust gas treatment catalyst according to [4]. 3. A catalyst for exhaust gas treatment, comprising a catalyst containing oxides of titanium, molybdenum and vanadium, characterized by containing molybdenum oxide particles having a particle size of 1 μm or more and 20 μm or less. 4. A method for treating exhaust gas, which comprises treating the exhaust gas containing nitrogen oxides with the catalyst according to any one of claims 1 to 3. 5. A method for treating exhaust gas, which comprises treating an exhaust gas containing an organic halogen compound using the catalyst according to any one of claims 1 to 3.