JP2020146610A - Denitration catalyst and method for producing the same - Google Patents

Abstract

To provide a denitration catalyst that is useful as an industrial catalyst having a high NOX removal rate, a low SO3 conversion rate, a high compression strength, and a low pressure loss when used.SOLUTION: A denitration catalyst contains an oxide component (A) containing titanium and containing tungsten and/or vanadium, and kaolinite (B) having an average particle size of 3.0 μm or more by Stokes method.SELECTED DRAWING: None

Description

The present invention relates to a denitration catalyst and a method for producing the same, and more specifically, in exhaust gas from a heavy oil or coal-fired boiler, a combustion furnace attached to various chemical devices, a steelmaking plant, or an internal combustion engine such as a diesel engine or a turbine. It relates to a denitration catalyst preferably used for reducing and detoxifying nitrogen oxides (hereinafter abbreviated as "NO _X ") contained in the above, and a method for producing the same.

As a denitration catalyst for removing NO _X in exhaust gas using a reducing agent such as ammonia, a honeycomb-shaped catalyst molded product in which an active component such as tungsten oxide or vanadium oxide is generally supported on a titanium oxide carrier is industrially used. It is used. Industrially used denitration catalyst moldings simply have high denitration activity because it is necessary to deal with dust and sulfur compounds (hereinafter abbreviated as "SO _X ") contained in the exhaust gas. well only the oxidation capability of the SO ₃ (SO ₃ conversion rate) is low, the compressive strength, the stronger the abrasion strength, various performances such that the pressure loss is low in use is required.

Generally, most of SO _X contained in exhaust gas is SO ₂ , but a part of this SO ₂ is oxidized on a denitration catalyst to become SO ₃ , and this SO ₃ is not NH ₃ used as a reducing agent. There are problems that it combines with the reaction component to generate acidic sulfur dioxide, which causes blockage of equipment such as the heat exchanger in the wake, and that SO ₃ itself causes corrosion of the equipment. Therefore, a denitration catalyst having a low SO ₃ conversion rate has been desired.

Patent Document 1 according to the proposals of the present applicants describes preparation of a denitration catalyst, which comprises forming a ternary composite oxide of titanium, tungsten and silicon in advance, and then adding a vanadium compound to the oxide. The method is disclosed. Patent Document 2 discloses a denitration catalyst molded product produced from a ternary composite oxide of titanium, tungsten and silicon, titanium oxide or a precursor thereof, and vanadium oxide or a precursor thereof. Further, Patent Document 3 discloses a denitration catalyst in which a vanadium compound is localized near the surface of a porous molded product made of a mixture of titanium oxide and tungsten oxide. These catalysts are characterized by high denitration activity and low SO ₃ conversion rate.

Further, in Patent Document 4, a non-noble metal transition metal compound (oxide such as vanadium or tungsten) is supported as a catalytically active component on a carrier composed of titanium oxide and a clay-based inorganic substance having a particle size of 0.1 to 100 μm. A catalyst for reducing ammonia is disclosed. This catalyst has high activity and excellent pressure resistance.

On the other hand, even a catalyst having high denitration activity is difficult to put into practical use unless it can be molded into a desired shape such as a honeycomb shape, a ring shape, a columnar shape, or a spherical shape.
A molding aid is often used to improve the moldability of the catalyst, and a clay substance is generally used as a typical molding aid. However, since the main components of the clay substance are SiO ₂ and Al ₂ O _{3, if} it is used for molding a titanium-based denitration catalyst, the denitration activity may decrease.

Japanese Unexamined Patent Publication No. 59-21342 Japanese Unexamined Patent Publication No. 11-342333 Japanese Unexamined Patent Publication No. 56-168835 Japanese Unexamined Patent Publication No. 52-126690

There is room for further improvement in the prior art from the viewpoint of realizing a denitration catalyst molded product having high denitration activity, low SO ₃ conversion rate, excellent moldability when molding into a honeycomb shape, and high compression strength. was there.

Therefore, according to the present invention, when ammonia is added to an exhaust gas containing NO _X and SO _X at the same time to cause a contact reaction, the denitration activity is high (that is, the NO _X removal rate is high), the SO ₃ conversion rate is low, and the honeycomb is formed. An object of the present invention is to provide a denitration catalyst having excellent moldability when molding into a shape and having high compressive strength, and a method for producing the same.

As a result of diligent research, the present inventors have found that the above-mentioned problems can be solved by blending kaolinite having an average particle diameter of 3.0 μm or more into the catalyst base material, and have completed the present invention.
The present invention relates to the following [1] to [8].

[1]
A denitration catalyst containing an oxide component (A) containing titanium and tungsten and / or vanadium, and kaolinite (B) having an average particle size of 3.0 μm or more according to the Stokes method.
[2]
The denitration catalyst of the above [1], wherein the oxide component (A) contains at least one of the following (A1) to (A4).
(A1) Titanium oxide (A2) Titanium and tungsten binary composite oxide (A3) Titanium and vanadium binary composite oxide (A4) Titanium, tungsten and vanadium ternary composite oxide [3]
The denitration catalyst of the above [1] or [2] further containing the strength-imparting agent (C).
[4]
The denitration catalyst according to any one of the above [1] to [3], wherein the content of the oxide component (A) is 60 to 99% by mass and the content of the kaolinite (B) is 1 to 40% by mass. ..
[5]
The denitration catalyst according to any one of the above [1] to [4], which is a molded product.
[6]
The denitration catalyst according to the above [5], which is a honeycomb-shaped molded product.
[7]
The denitration catalyst according to the above [6], which has a compression strength of 85 N / cm ² or more.
[8]
A raw material (a) of an oxide component (A) containing titanium and / or tungsten and / or vanadium, kaolinite (B) having an average particle size of 3.0 μm or more by the Stokes method, and optionally other components are mixed. A method for producing a denitration catalyst, which is then optionally molded and then fired.

The denitration catalyst of the present invention has high denitration activity, low SO ₃ conversion rate, high compressive strength, and excellent moldability. Therefore, by using the denitration catalyst of the present invention, NO _X in the exhaust gas can be effectively and economically reduced and harmless, and the conversion rate to SO ₃ is low, so that the corrosion of the apparatus can be suppressed.

Further, according to the production method of the present invention, it is possible to produce a denitration catalyst having high denitration activity, low SO ₃ conversion rate, high compression strength, and excellent moldability.

Embodiments of the present invention will be described in detail below.
[Denitration catalyst]
The denitration catalyst of the present invention is characterized by containing an oxide component (A) containing titanium and containing tungsten and / or vanadium, and kaolinite (B) having an average particle size of 3.0 μm or more according to the Stokes method. It is said.

(A) Oxide component:
The oxide component (A) is an oxide component containing titanium and / or tungsten and / or vanadium. In other words, the oxide component (A) is an oxide of a metal, which contains titanium as the metal, and also contains tungsten and / or vanadium.

The oxide component (A) preferably contains any one or more of the following (A1) to (A4).
(A1) Titanium oxide;
(A2) Titanium and Tungsten Binary Composite Oxide (hereinafter also referred to as "TIO _2- WO ₃ Binary Composite Oxide");
(A3) Titanium and vanadium binary composite oxide (hereinafter, also referred to as "TiO _2- V ₂ O ₅ binary composite oxide");
(A4) A ternary composite oxide of titanium, tungsten and vanadium (hereinafter, also referred to as "TIO _2- WO _3- V ₂ O ₅ ternary composite oxide").

The TiO _2- WO ₃ binary composite oxide, the TiO _2- V ₂ O ₅ binary composite oxide, and the TiO _2- WO _3- V ₂ O ₅ ternary composite oxide) are oxidized. It is not simply a mixture of titanium, tungsten oxide and / or vanadium oxide, but its unique performance is exhibited by forming the binary system or the ternary system composite oxide in advance. The advantage of using a binary or ternary composite oxide of titanium and tungsten and / or vanadium is that the resulting catalyst exhibits high denitration activity and low SO ₃ conversion.

As the oxide component (A), titanium oxide is mixed with a solution of a precursor containing tungsten and / or a precursor containing vanadium, and aqueous ammonia is further added to obtain an oxide component containing tungsten and / or vanadium. Examples thereof include those obtained by precipitating, then removing the solvent in the solution, and firing the solid content residue (the firing temperature is, for example, 300 to 800 ° C.).

The vanadium content (converted to V ₂ O ₅ content) in the oxide component (A) is preferably 0.1% by mass or more, more preferably 0.3, from the viewpoint of suppressing the SO ₃ conversion rate. It is preferably 10% by mass or less, more preferably 8.0% by mass or less, because it is by mass or more, has high denitration activity, and has good moldability.

The tungsten content (converted to WO ₃ content) in the oxide component (A) is preferably 1 to 40% by mass, and more preferably 2 to 25% by mass.
The titanium content (converted to the TIO ₂ content) is the vanadium content (converted to the V ₂ O ₅ content) and the tungsten content (WO ₃ content) from the amount of the oxide component (A). It is the amount (balance) after deducting.).

The TiO _2- WO ₃ binary composite oxide, the TiO _2- V ₂ O ₅ binary composite oxide, and the TIM _2- WO _3- V ₂ O ₅ ternary composite oxide are, for example, It is prepared by the method described in JP-A-11-342333. Specifically, the following method is exemplified.

(1) Ammonia water, water or the like is added to a liquid or aqueous solution of a water-soluble titanium compound such as titanium tetrachloride, titanyl sulfate or tetraalkoxytitanium and hydrolyzed to obtain a titanium hydroxide. Oxidation of a precursor of tungsten oxide composed of a water-soluble salt of tungsten such as ammonium paratungstate and ammonium metatungstate as it is, or as an aqueous solution, composed of a water-soluble salt of vanadium such as ammonium metavanadate and vanadium sulfate. The precursor of vanadium is added as it is or as an aqueous solution simultaneously or sequentially, mixed, dried, and further fired at 150 to 800 ° C.

(2) The above-mentioned water-soluble compound of titanium is mixed with the above-mentioned precursor of vanadium oxide and the above-mentioned precursor of tungsten oxide, and aqueous ammonia is added to form a precipitate. The precipitate is washed and dried, and then 150 to Bake at 800 ° C.

(3) Titanium oxide powder is mixed with the above-mentioned precursor of vanadium oxide and the above-mentioned precursor of tungsten oxide, and aqueous ammonia is added to form a precipitate. The precipitate is washed, dried and then calcined at 150 to 800 ° C. To do.

(4) The above-mentioned precursor of vanadium oxide and the above-mentioned precursor of tungsten oxide are added to metatitanic acid, mixed and dried, and then fired at 150 to 800 ° C.

(B) Kaolinite:
The denitration catalyst of the present invention contains kaolinite (B). The average particle size of kaolinite (B) by the Stokes method described in detail below is 3.0 μm or more, more preferably 3.2 μm or more. On the other hand, when the average particle size is excessively smaller than 3.0 μm, the moldability is inferior, such as cracks occurring during molding, and the denitration activity is lowered.
The average particle size of kaolinite (B) is preferably 7.0 μm or less, more preferably 6.0 μm or less, from the viewpoint of excellent moldability of the denitration catalyst and low SOx conversion rate.

<Measuring method of average particle size by Stokes method>
Kaolinite is added to a 0.2% sodium pyrophosphate solution prepared with pure water and sodium pyrophosphate to prepare a suspension (solid content concentration: 1% by mass). After dispersing the prepared suspension with an ultrasonic disperser for 5 minutes, the kaolinite in the liquid was subjected to an X-ray transmission type sedimentation method particle size distribution measuring device (for example, SediGraphTM III5120 manufactured by MICROMERITICS). Measure the average particle size (Stokes size).

(C) Strength-imparting agent:
The denitration catalyst of the present invention preferably contains a strength-imparting agent (C). The denitration catalyst of the present invention is more excellent in mechanical strength (compressive strength, etc.) when it contains the strength-imparting agent (C).
Examples of the strength-imparting agent (C) include inorganic fibers, synthetic fibers, and ceramic powder.

Examples of the inorganic fiber include carbon fiber, ceramic fiber, and glass fiber, and examples of the synthetic fiber include polyester fiber, polyamide fiber, aramid fiber, polyacrylonitrile fiber, and the like. Examples include powders of cordierite, alumina, zirconia, silicon nitride, silicon carbide and the like.

The content of the oxide component (A) in the denitration catalyst of the present invention is preferably 60% by mass or more, more preferably 65% by mass or more, and the denitration catalyst is a honeycomb molded body from the viewpoint of exhibiting high denitration activity. In some cases, it is more preferably 75% by mass or more, and from the viewpoint of exhibiting high moldability, it is preferably 99% by mass or less, more preferably 97% by mass or less, and when the denitration catalyst is a honeycomb molded body. More preferably, it is 96% by mass or less.

The content of the kaolinite (B) in the denitration catalyst of the present invention is preferably 1% by mass or more from the viewpoint of exhibiting high moldability, exhibiting high compressive strength, and suppressing SO ₃ conversion rate. It is more preferably 3% by mass or more, further preferably 4% by mass or more when the denitration catalyst is a honeycomb molded body, and preferably 40% by mass or less, more preferably 35 from the viewpoint of exhibiting high denitration activity. It is 50% by mass or less, more preferably 25% by mass or less when the denitration catalyst is a honeycomb molded body.

The content of the strength-imparting agent (C) in the denitration catalyst of the present invention is preferably 0.1% by mass or more, more preferably 0., From the viewpoint of exhibiting high compressive strength and exhibiting high denitration activity. It is 5% by mass or more, preferably 20% by mass or less, and more preferably 15% by mass or less from the viewpoint of suppressing the SO ₃ conversion rate.

Denitration catalyst of the present invention has a specific surface area measured by the BET method to be described below (SA _BET) is preferably a 35~100m ² / g, more preferably 40~90m ² / g.

<Measuring method of BET method (BET specific surface area)>
A dried sample (0.2 g) is placed in a measurement cell, degassed at 300 ° C. for 60 minutes in a nitrogen gas stream, and then the sample is placed in a mixed gas stream of 30% by volume of nitrogen and 70% by volume of helium. Keep the temperature at liquid nitrogen and allow nitrogen to equilibrate and adsorb to the sample. Next, the temperature of the sample is gradually raised to room temperature while flowing the mixed gas, the amount of nitrogen desorbed during that period is detected, and the specific surface area of the sample is measured by a calibration curve prepared in advance.

Such a BET specific surface area measurement method (nitrogen adsorption method) can be performed using, for example, a conventionally known surface area measuring device.
The denitration catalyst of the present invention preferably has a pore volume (PV _Hg ) of 0.1 to 1.0 ml / g, and is 0.3 to 0.8 ml / g, as measured by the mercury intrusion porosimmetry method. Is more preferable.

The mercury intrusion porosymmetry method is a mercury intrusion method using a porosimeter, and can be measured using, for example, a conventionally known measuring device.
The denitration catalyst of the present invention may be a molded product (hereinafter, also referred to as “denitration catalyst molded product”), and examples of the shape of the denitration catalyst molded product include honeycomb shape, ring shape, columnar shape, and spherical shape. In particular, a honeycomb-shaped denitration catalyst molded product is suitable because it has a low pressure loss during use.

When the denitration catalyst of the present invention is a honeycomb-shaped denitration catalyst molded product, the compression strength measured by the method described in detail below is preferably 85 N / cm ² or more, more preferably 85 to 110 N / cm ^2. Is. When the compressive strength is in the above range, it is preferable for actual use as an industrial catalyst.

<Measurement method of compression strength>
A measurement sample having a cube shape with a side of 70 mm (however, the normal direction of the two facing surfaces and the longitudinal direction of the cell in the honeycomb structure are matched) is cut out from the honeycomb-shaped denitration catalyst molded product, and the compression strength is obtained. Place it on a testing machine (eg, manufactured by Tokyo Testing Machine Mfg. Co., Ltd .: model AC / B30P, maximum compression load 30,000 kN) and apply a load in the direction perpendicular to the longitudinal direction of the cells in the honeycomb structure of the measurement sample, and the measurement sample is completely completed. Read the load at the time of destruction (hereinafter referred to as "maximum load"), and calculate the compressive strength (N / cm ² ) by the following formula.
Compressive strength (N / cm ² ) = maximum load (N) / (7.0 (cm) x 7.0 (cm))

Denitration catalyst of the present invention, the exhaust gas containing NO _X, in particular NO _X, such as boiler exhaust gas, in addition heavy metal containing SO _X, the exhaust gas containing dust, catalytic reduction by adding a reducing agent such as ammonia It is preferably used in the NO _X removal method.

As the conditions for using the denitration catalyst of the present invention, ordinary denitration treatment conditions are adopted. Specifically, the reaction temperature is 150 to 600 ° C., and the space velocity is in the range of 1,000 to 100,000 h ^-1. Will be done.

[Manufacturing method of denitration catalyst]
The method for producing a denitration catalyst of the present invention is a raw material (a) of an oxide component (A) containing titanium and tungsten and / or vanadium, and kaolinite (B) having an average particle size of 3.0 μm or more by the Stokes method. ), And optionally other components, then optionally molded and then fired.

As an example of the method for producing the denitration catalyst of the present invention, titanium oxide, a precursor containing tungsten and / or a precursor containing vanadium or a solution thereof (the above is the raw material (a)), and the kaolinite (the above is the raw material (a)). B) is mixed, and aqueous ammonia is further added to precipitate an oxide component containing tungsten and / or vanadium, and then the strength-imparting agent (C) is optionally added, and a processing aid (D) is optionally added. In addition, there is a method of further mixing and then molding, then removing the solvent in the solution, and then firing.

Titanium oxide is preferably in the form of powder.
Examples of precursors containing tungsten include water-soluble salts of tungsten such as ammonium paratungstate and ammonium metatungstate.

Examples of precursors containing vanadium include water-soluble salts of vanadium such as vanadium oxide, vanadyl sulfate, vanadyl oxalate, and ammonium metavanadate.
The processing aid (D) is added to enhance the moldability of the mixture to be molded, and examples thereof include organic substances such as methyl cellulose, carboxymethyl cellulose, polyethylene oxide, polyacrylic amide, polyvinyl alcohol, and starch.

The amounts of the raw material (a), kaolinite (B) and the strength-imparting agent (C) are preferably those of the oxide component (A), kaolinite (B) and the strength-imparting agent (C) in the produced denitration catalyst. The ratio of each component is set so as to be within the above range. The amount of the precursor containing titanium oxide and tungsten and the precursor containing vanadium is preferably set so that the ratio of titanium, tungsten and vanadium in the produced oxide component (A) is within the above range. To.

The solvent for the solution of the precursor containing tungsten and / or the precursor containing vanadium is preferably water. The solvent may contain an auxiliary agent (such as monoethanolamine) for increasing the water solubility of the water-soluble salt.

Examples of the method for removing the solvent of the solution include natural drying, hot air drying and the like.
The firing is preferably carried out at 300 to 800 ° C.
The firing is preferably carried out for 0.5 to 24 hours.
Further, the firing is preferably carried out in an air atmosphere or an inert gas atmosphere.
According to the production method of the present invention, the denitration catalyst of the present invention described above can be produced.

Hereinafter, the present invention will be specifically described with reference to examples, but the present invention is not limited thereto.
<Evaluation method>
(Denitration performance)
A measurement sample cut out into a predetermined shape from the denitration catalyst molded product produced in Examples and the like was filled in a flow reactor, and the denitration rate was measured under the following conditions. The denitration rate was determined by measuring the concentration of nitrogen oxide NOx in the gas before and after contact with the catalyst with a Chemilmi-type nitrogen oxide analyzer and using the following formula.
Denitration rate (%) = [NOx (ppm) in non-contact gas-NOx (ppm) in contact gas] / NOx (ppm) in non-contact gas x 100
Test conditions-Catalyst shape: 3 x 3 stitches, length 300 mm
-Reaction temperature: 380 ° C
・ SV: 10000h ^-1
-Gas composition: NO _x = 180ppm, NH ₃ = 216ppm, O ₂ = 2%, SO ₂ = 500ppm, H ₂ O = 10%, N ₂ = balance

(SO _X Oxidizing ability)
A measurement sample cut out into a predetermined shape from the denitration catalyst molded product produced in Examples and the like was filled in a flow reactor, and the SO ₃ conversion rate was measured under the following conditions. The SO ₃ conversion rate was calculated by measuring the SO ₂ concentration in the gas before and after contact with the catalyst with an infrared SO ₂ gas concentration meter and using the following formula.
SO ₃ conversion ratio (%) = [untouched gas of SO ₂ (ppm) - SO ₂ in contact in the gas (ppm)] / non-contact gas SO ₂ (ppm) × 100
Test conditions-Catalyst shape: 3 x 3 stitches, length 300 mm
-Reaction temperature: 380 ° C
・ SV: 10000h ^-1
・ Gas composition: O ₂ = 2%, SO ₂ = 500ppm, N ₂ = balance

(Moldability)
The appearance of the denitration catalyst molded product produced in Examples and the like and the production process (after drying and before firing) was visually observed.

(Compression strength)
A measurement sample having a cube shape with a side of 70 mm (however, the normal direction of the two facing surfaces matches the longitudinal direction of the cell in the honeycomb structure) is cut out from the denitration catalyst molded product produced in the examples and the like. This is placed on a compressive strength tester (manufactured by Tokyo Testing Machine Mfg. Co., Ltd .: model AC / B30P, maximum compressive load 30000 kN), and a load is applied in a direction perpendicular to the longitudinal direction of the cell in the honeycomb structure in the measurement sample to obtain the maximum load. (N) was read, and the compression strength (N / cm ² ) defined by the following equation was calculated.
Compressive strength (N / cm ² ) = maximum load (N) / (7.0 (cm) x 7.0 (cm))

(Pore volume)
The pore volume of the denitration catalyst molded product produced in Examples and the like was measured by a mercury intrusion porosimometry method.

(Specific surface area)
The specific surface area of the denitration catalyst molded product produced in Examples and the like was measured by the BET method.

[Example 1]
168.2 g of ammonium metavanadate (NH ₄ VO ₃ ) was boiled and dissolved at 105 ° C. in a mixed solution of 200 g of monoethanolamine and 2000 ml of pure water to obtain a vanadium salt solution A. Vanadium salt solution A, titanium oxide powder (manufactured by Ishihara Sangyo Co., Ltd., MC-90) 20.77 kg, and kaolinite (manufactured by IMERYS, Hydrite Flat DS) having an average particle diameter of 5.0 μm were added to 2500 g on a drying basis. 1500 g of ammonium paratungstate was placed in a kneader, and while stirring, 500 m1 of 15% aqueous ammonia and 2000 ml of pure water were further added and mixed. Then, it was heated while mixing to evaporate the water content. When the mixture changed from slurry to clay, heating was stopped, and 60 g of carboxymethyl cellulose and 60 g of polyvinyl alcohol were added to the mixture as processing aids, and E glass chop strands (fiber length 5 mm, fiber diameter 9 μm: fiber diameter 9 μm: Nitto Boseki) were used as strength-imparting agents. 1250 g (manufactured by Co., Ltd.) was added and mixed and kneaded to obtain a mixed kneaded product A.

This mixed product A was molded into a honeycomb shape by a vacuum extruder with a screw equipped with a honeycomb extrusion die. After allowing this molded product to air dry for a sufficient period of time, and then drying it for 2 days while ventilating it with hot air at 60 ° C. Baking for a time gave a honeycomb-shaped denitration catalyst molded product A having a cell pitch of 7.4 mm, a wall thickness of 1.0 mm, a cross-sectional shape in the longitudinal direction of 70 mm on a side, and a length of 500 mm. Table 1 shows the evaluation results of the denitration catalyst molded product A.

[Example 2]
A denitration catalyst molded product B was obtained in the same manner as in Example 1 except that kaolinite was changed to 2500 g of kaolinite (manufactured by BASF, ASP-400P) having an average particle size of 3.5 μm on a drying basis. Table 1 shows the evaluation results of the denitration catalyst molded product B.

[Example 3]
Example 1 except that the amount of titanium oxide powder was changed to 22.09 kg and kaolinite was changed to kaolinite (manufactured by BASF, ASP-400P) having an average particle diameter of 3.5 μm of 1250 g on a drying basis. A denitration catalyst molded product C was obtained by the same method. Table 1 shows the evaluation results of the glass catalyst molded product C.

[Example 4]
336.4 g of ammonium metavanadate (NH ₄ VO ₃ ) was boiled and dissolved at 105 ° C. in a mixed solution of 400 g of monoethanolamine and 4000 ml of pure water to obtain a vanadium salt solution B. A denitration catalyst molded product D was obtained by the same method as in Example 2 except that the vanadium salt solution A was changed to the vanadium salt solution B and the amount of titanium oxide powder was changed to 20.63 kg. Table 1 shows the evaluation results of the denitration catalyst molded product D.

[Example 5]
The denitration catalyst molded product E was prepared by the same method as in Example 4 except that the amount of titanium oxide powder was changed to 17.99 kg and the amount of kaolinite having an average particle diameter of 3.5 μm was changed to 5000 g based on the drying standard. Obtained. Table 1 shows the evaluation results of the denitration catalyst molded product E.

[Comparative Example 1]
The denitration catalyst molded product R1 was obtained by the same method as in Example 1 except that the amount of titanium oxide powder was changed to 23.41 kg and kaolinite was not used. Table 1 shows the evaluation results of the denitration catalyst molded product R1.

[Comparative Example 2]
Denitration catalyst molded product R2 by the same method as in Example 1 except that kaolinite was changed to acidic white clay (manufactured by Mizusawa Chemical Co., Ltd., Mizuka Ace # 400) having an average particle size of 2.6 μm of 2500 g based on drying. Got Table 1 shows the evaluation results of the denitration catalyst molded product R2.

[Comparative Example 3]
Kaolinite with an average particle size of 3.5 μm was denitrated by the same method as in Example 1 except that it was changed to 2500 g of kaolinite with an average particle size of 0.25 μm (AMAZON Plus, manufactured by KaMin and CADAM). A catalyst molded product R3 was obtained. Table 1 shows the evaluation results of the denitration catalyst molded product R3.

[Comparative Example 4]
A denitration catalyst molded product R4 was obtained by the same method as in Example 1 except that kaolinite was changed to kaolinite (manufactured by Thile, RC-32) having an average particle diameter of 1.2 μm of 2500 g on a drying basis. Table 1 shows the evaluation results of the denitration catalyst molded product R4.

[Comparative Example 5]
Kaolinite was changed to 2500 g of kaolinite with an average particle size of 3.0 μm (obtained by crushing natural zeolite CP (mordenite) of Shin-Tohoku Chemical Industry Co., Ltd. with a dry crusher). A denitration catalyst molded product R5 was obtained by the same method as in Example 1 except for the above. Table 1 shows the evaluation results of the denitration catalyst molded product R5.

The catalyst molded product of the example had good moldability, high compressive strength, high denitration rate, and low SO ₃ conversion rate.

Claims (8)

A denitration catalyst containing an oxide component (A) containing titanium and tungsten and / or vanadium, and kaolinite (B) having an average particle size of 3.0 μm or more according to the Stokes method. The denitration catalyst according to claim 1, wherein the oxide component (A) contains any one or more of the following (A1) to (A4).
(A1) Titanium oxide (A2) Titanium and tungsten binary composite oxide (A3) Titanium and vanadium binary composite oxide (A4) Titanium, tungsten and vanadium ternary composite oxide The denitration catalyst according to claim 1 or 2, further containing a strength-imparting agent (C). The denitration according to any one of claims 1 to 3, wherein the content of the oxide component (A) is 60 to 99% by mass, and the content of the kaolinite (B) is 1 to 40% by mass. catalyst. The denitration catalyst according to any one of claims 1 to 4, which is a molded product. The denitration catalyst according to claim 5, which is a honeycomb-shaped molded product. The denitration catalyst according to claim 6, wherein the compression strength is 85 N / cm ² or more. A raw material (a) of an oxide component (A) containing titanium and tungsten and / or vanadium, kaolinite (B) having an average particle size of 3.0 μm or more by the Stokes method, and optionally other components are mixed. A method for producing a denitration catalyst, which is then optionally molded and then fired.