JP2017170307A - Method for producing honeycomb type denitration catalyst - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide means capable of improving abrasion resistance while suppressing the deterioration of denitration performance of a honeycomb type denitration catalyst.SOLUTION: There is provided a method for producing a honeycomb type denitration catalyst by molding and baking a catalyst paste obtained by kneading a catalyst paste precursor containing a first oxide selected from a titanium oxide, a titanium-silicon mixed oxide and/or composite oxide, a titanium-tungsten mixed oxide and/or composite oxide or a titanium-silicon-tungsten mixed oxide and/or composite oxide, a second oxide composed of a titanium oxide and at least one active component selected from vanadium, tungsten and molybdenum, wherein the content of water in the catalyst paste precursor is adjusted to 450 to 550 g/kg based on the total mass and the content of the second oxide in the catalyst paste precursor is adjusted to 2 to 40 mass% based on the total mass.SELECTED DRAWING: Figure 1

Description

  The present invention relates to a method for producing a honeycomb-type denitration catalyst (a catalyst for removing nitrogen oxides). The honeycomb type denitration catalyst (nitrogen oxide removal catalyst) according to the present invention includes, for example, a heavy oil fired boiler, a coal fired boiler, a gas fired boiler, a gas turbine, a gas engine, a diesel engine, a thermal power plant, a waste incinerator, and various types Used to remove nitrogen oxides (NOx) contained in exhaust gas discharged from industrial processes.

  Generally, nitrogen oxides (NOx) are present in exhaust gas discharged from heavy oil fired boilers, coal fired boilers, gas fired boilers, gas turbines, gas engines, diesel engines, thermal power plants, waste incinerators and various industrial processes. include. As a method for removing nitrogen oxides currently in practical use for the purpose of removing nitrogen oxides in the exhaust gas, the nitrogen oxides in the exhaust gas are contacted on the catalyst using a reducing agent such as ammonia or urea. A selective catalytic reduction method (SCR method) which reduces to nitrogen and water is common. In recent years, as environmental pollution caused by nitrogen oxides has become serious worldwide, as represented by acid rain, a high-performance catalyst has been demanded.

  On the other hand, since the exhaust gas contains an acid gas such as sulfur oxide (SOx), the catalyst used for the treatment of the exhaust gas has SOx resistance in addition to NOx removal performance. From this point of view, a titania-based catalyst is considered promising.

Here, by making the titania-based denitration catalyst into the form of a honeycomb-type catalyst, the surface area and pore volume of the catalyst are increased, and a highly active denitration catalyst exhibiting high performance even at low temperature and high space velocity is performed. It has been broken. However, the honeycomb type catalyst has a disadvantage that its strength is small, and particularly the contact surface with the gas is weak against abrasion. For example, when used in a coal fired boiler, the exhaust gas often contains several hundred mg / m ³ to several tens g / m ³ of coal combustion ash and the like as dust. When exhaust gas containing a large amount of dust is treated with a titania-based denitration catalyst in the form of a honeycomb-type catalyst, the contact surface with the gas is worn by dust, and the exhaust gas treatment efficiency is reduced, or dust is combined with exhaust gas. There is a possibility of causing problems such as secondary pollution caused by being discharged to the outside and clogging of the catalyst layer in the wake layer.

Conventionally, for the purpose of improving the wear resistance of a denitration catalyst, one or more elements of titanium oxide (TiO ₂ ) and vanadium (V), molybdenum (Mo), tungsten (W), and iron (Fe) are used. A first component comprising a dried or calcined powder and a second component comprising a hydrous titanium oxide powder, wherein the active component is supported by heating and kneading on titanium oxide. There has been proposed a technique for obtaining a denitration catalyst by drying and firing the kneaded product (see Patent Document 1).

  A magnesium sulfate aqueous solution is formed on a porous molded body containing 5 to 20 parts by weight of tungsten trioxide and 0 to 2.0 parts by weight of vanadium pentoxide with respect to 100 parts by weight of titanium oxide or titanium oxide-silica composite oxide. In addition, a technique for obtaining a denitration catalyst by impregnating and heating and firing magnesium sulfate in the range of 0.5 to 5.5 parts by weight on the porous molded body has been proposed (see Patent Document 2). ).

JP-A-7-163876 Japanese Patent Laid-Open No. 9-276659

  As a result of investigations by the present inventors, it has been found that the denitration catalyst disclosed in Patent Documents 1 and 2 still does not have sufficient wear resistance as a honeycomb catalyst. On the other hand, it has also been found that there is a trade-off that if the wear resistance is improved, the denitration performance is lowered in some cases.

  Accordingly, an object of the present invention is to provide means for improving the wear resistance of a honeycomb type denitration catalyst while minimizing a decrease in the denitration performance.

  The present inventors have intensively studied to solve the above problems. As a result, a catalyst paste obtained by kneading a catalyst paste precursor containing a predetermined first oxide, a second oxide made of titanium oxide, a predetermined active component, and water is used as a honeycomb. When the honeycomb-type denitration catalyst is manufactured by being shaped into a shape and fired, the water content in the catalyst paste precursor is controlled to a value within a predetermined range, and the first oxide in the catalyst paste precursor and It has been found that the above problem can be solved by controlling the blending ratio with the second oxide to a value within a predetermined range, and the present invention has been completed.

  That is, according to one aspect of the present invention, titanium oxide, titanium-silicon mixed oxide and / or composite oxide, titanium-tungsten mixed oxide and / or composite oxide, and titanium-silicon-tungsten At least one selected from the group consisting of a first oxide selected from the group consisting of mixed oxides and / or complex oxides, a second oxide consisting of titanium oxides, and vanadium, tungsten and molybdenum A method for producing a honeycomb-type denitration catalyst comprising kneading a catalyst paste precursor containing the active ingredient and water to obtain a catalyst paste, and molding and firing the catalyst paste into a honeycomb shape. Provided. In the production method, the water content in the catalyst paste precursor is 450 to 550 g / kg per total mass of the first oxide and the second oxide, and in the catalyst paste precursor. It is characterized in that the content of the second oxide is 2 to 40% by mass with respect to the total mass of the first oxide and the second oxide.

  ADVANTAGE OF THE INVENTION According to this invention, the honeycomb type denitration catalyst which improved abrasion resistance can be provided, suppressing the fall of denitration performance to the minimum.

FIG. 10 is a flowchart corresponding to the manufacturing method of Example 9.

  Hereinafter, specific embodiments for carrying out the present invention will be described in detail with reference to the drawings. The technical scope of the present invention should be determined based on the description of the claims, and It is not limited only to the form.

  According to one aspect of the present invention, titanium oxide, titanium-silicon mixed oxide and / or composite oxide, titanium-tungsten mixed oxide and / or composite oxide, and titanium-silicon-tungsten mixed oxidation At least one activity selected from the group consisting of a first oxide selected from the group consisting of oxides and / or complex oxides, a second oxide consisting of titanium oxide, and vanadium, tungsten and molybdenum A catalyst paste precursor containing components and water is kneaded to obtain a catalyst paste (hereinafter also referred to as “step (1)”), and the catalyst paste is formed into a honeycomb and fired ( Hereinafter, also referred to as “step (2)”), a method for producing a honeycomb type denitration catalyst, wherein the water content in the catalyst paste precursor is 450 to 550 g / kg per total mass of the first oxide and the second oxide, and the content of the second oxide in the catalyst paste precursor is the first oxidation A method for producing a honeycomb-type denitration catalyst is provided, which is 2 to 40% by mass with respect to the total mass of the product and the second oxide.

[Step (1)]
Step (1) is a step of obtaining a catalyst paste by kneading this after obtaining a catalyst paste precursor containing a predetermined raw material.

(Catalyst paste precursor)
The catalyst paste precursor essentially includes a first oxide, a second oxide, an active component, and water, and may further include additives such as inorganic fibers and a binder as necessary.

First oxide The first oxide contained in the catalyst paste precursor is an oxide selected from the group consisting of:
Titanium oxide (TiO ₂ );
Titanium-silicon mixed oxide (a mixture of TiO ₂ and SiO ₂ );
Titanium-silicon composite oxide (TiO ₂ —SiO ₂ composite oxide (also referred to as “TS composite oxide”));
Titanium-tungsten composite oxide (TiO ₂ —WO ₃ composite oxide (also referred to as “TW composite oxide”));
Titanium-tungsten mixed oxide (mixture of TiO ₂ and WO ₃ );
Titanium-silicon-tungsten composite oxide (TiO ₂ —SiO ₂ —WO ₃ composite oxide (also referred to as “TSW composite oxide”));
Titanium-silicon-tungsten mixed oxide (a mixture of TiO ₂ , SiO ₂ and WO ₃ , a TS composite oxide or a mixture of a TSW composite oxide and WO ₃ , a TW composite oxide or a TSW composite oxide and SiO ₂ A mixture of TS composite oxide and TW composite oxide (and a mixture of SiO ₂ and / or WO ₃ if necessary)).

In the denitration catalyst and the production method thereof according to the present embodiment, it is more preferable that the first oxide contains a silicon oxide (SiO ₂ ) from the viewpoint of achieving both denitration performance and wear resistance. That is, the first oxide is preferably selected from the group consisting of a titanium-silicon mixed oxide and / or composite oxide and a titanium-silicon-tungsten mixed oxide and / or composite oxide.

Note that the first oxide includes titanium oxide (TiO ₂ ) as an essential component. However, when the first oxide also includes components other than titanium oxide (TiO ₂ ), The content of titanium oxide (TiO ₂ ) is preferably 70 to 99.9% by mass in terms of oxide, and more preferably 80 to 99.5% by mass.

The average particle diameter of the first oxide is preferably 1 to 50 μm, more preferably 2 to 50 μm, and further preferably 2 to 40 μm. When the average particle size of the first oxide is 1 to 50 μm, there is an advantage that a close bond with the second oxide can be formed to improve the catalyst strength and the wear strength. In addition, the value measured by the method called the laser diffraction scattering method shall be employ | adopted for the value of the average particle diameter of a 1st oxide and the 2nd oxide mentioned later using a particle diameter distribution measuring apparatus. Further, the BET specific surface area of the first oxide is preferably 70 to 250 m ² / g, more preferably 80 to ²⁰⁰ m ² / g, and further preferably 90 to 180 m ² / g. If the BET specific surface area of the first oxide is 70 to 250 m ² / g, the amount of water to be added when the first oxide, the second oxide, and the salt that is the raw material of the active ingredient are mixed. There is an advantage that it can be controlled within an appropriate range, and the catalyst strength and wear strength can be improved.

  As the first oxide, a commercially available product may be used, or a product prepared by itself may be used. As a method for preparing the composite oxide by itself among the first oxides, for example, there is a coprecipitation method (see Examples 8 to 9 described later). The method itself for obtaining a complex oxide by the coprecipitation method is conventionally known, and known knowledge can be referred to as appropriate. The composite oxide prepared by the coprecipitation method has excellent characteristics such as a high specific surface area, and the catalyst performance is also improved, so that it is more preferably used. At this time, titanium raw materials include titanium chloride, titanium sulfate, titanium tetrachloride, titanyl sulfate, and tetraisopropyl titanate, and silicon raw materials include silica sol, water glass, and silicon tetrachloride, and tungsten raw materials. Examples thereof include tungsten trioxide, tungstic acid, ammonium metatungstate, and ammonium paratungstate.

In DeNOx catalyst and the manufacturing method thereof according to the second oxide present embodiment, the catalyst paste precursor, together with the first of the aforementioned oxides, including titanium oxide (TiO ₂₎ as the second oxide. In the denitration catalyst and the manufacturing method thereof according to this embodiment, in addition to the first oxide described above, the second oxide (titanium oxide (TiO ₂ )) is used in combination at a predetermined ratio, thereby denitration. It is possible to obtain a denitration catalyst having excellent wear resistance while suppressing a decrease in performance. Specifically, in the manufacturing method according to this embodiment, the content of the second oxide in the catalyst paste precursor obtained in step (1) is the sum of the first oxide and the second oxide. The content is 2 to 40% by mass with respect to the mass. Preferably, the content of the second oxide is 5 to 25% by mass with respect to the total mass of the first oxide and the second oxide. If the content of the second oxide is less than 2% by mass, sufficient wear resistance cannot be realized. On the other hand, when the content of the second oxide exceeds 40% by mass, there is a problem that the denitration performance is deteriorated although the wear resistance is ensured.

The average particle diameter of the second oxide is preferably 0.5 to 5 μm, more preferably 0.5 to 3 μm. If the average particle diameter of the second oxide is 0.5 to 5 μm, there is an advantage that a close bond with the first oxide can be formed to improve the catalyst strength and wear strength. Further, the BET specific surface area of the second oxide is preferably 50 to 150 m ² / g, more preferably 70 to 120 m ² / g, and further preferably 80 to 120 m ² / g. If the BET specific surface area of the oxide is 50 to 150 m ² / g, the amount of water added when mixing the first oxide, the second oxide, and the salt that is the raw material of the active ingredient is appropriate. There is an advantage that the catalyst strength and the wear strength can be improved.

  In addition, about the 2nd oxide, what purchased the commercial item may be used and what was prepared itself may be used.

-Active component In the denitration catalyst and its manufacturing method which concern on this form, a catalyst paste precursor contains an active component. This active ingredient essentially contains at least one selected from the group consisting of vanadium, tungsten and molybdenum. These active components are usually supplied in the form of a compound containing the component or a solution thereof (for example, an aqueous solution) and introduced into the catalyst paste precursor. As the raw material (compound) of the active ingredient, for example, vanadium pentoxide, ammonium metavanadate, vanadyl sulfate, vanadyl oxalate as a vanadium raw material; tungsten trioxide, tungstic acid, ammonium metatungstate similar to the above as a tungsten raw material Ammonium paratungstate; examples of molybdenum raw materials include molybdenum trioxide, molybdic acid, and ammonium paramolybdate.

  Note that active ingredients other than the active ingredients described above may be included, and for example, silicon, aluminum, zirconium, and the like may be included. Further, as these raw materials, the same silica sol, water glass, and silicon tetrachloride as above as silicon raw materials; alumina, boehmite, aluminum nitrate, aluminum oxalate, aluminum sulfate as aluminum raw materials; zirconium oxide, zirconium nitrate, as zirconium raw materials, Examples include zirconium sulfate and zirconium oxychloride.

-Water In the denitration catalyst and the method for producing the same according to the present embodiment, the catalyst paste precursor contains water. In addition to the case where the water is introduced as a solvent of the solution when the active ingredient described above is introduced into the catalyst paste precursor, this water may be introduced by being added separately in the form of water alone.

  The denitration catalyst and the method for producing the same according to this embodiment are also characterized by the amount of water contained in the catalyst paste precursor. That is, the content of water in the catalyst paste precursor is 450 to 550 g / kg, preferably 475 to 525 g / kg, based on the total mass of the first oxide and the second oxide described above. If the amount of water is less than 450 g / kg, the wear resistance is ensured, but there is a problem that the denitration performance is lowered. On the other hand, if the amount of water exceeds 550 g / kg, sufficient wear resistance cannot be realized.

-Additive The catalyst paste precursor may contain additives other than the above-described components as necessary. Examples of such additives include reinforcing members made of inorganic fibers such as glass wool, silica sol, starch, polyvinyl alcohol, metroose (cellulose thickener, trade name of Shin-Etsu Chemical Co., Ltd.), carboxyl cellulose, and the like. A molding aid (binder) made of There is no restriction | limiting in particular about the addition amount of these additive seed | species and an additive, It can determine suitably, referring a conventionally well-known knowledge in the range which does not impair the effect of this invention.

(Kneading process)
Step (1) includes a step of kneading the catalyst paste precursor obtained above (kneading step). The catalyst paste precursor is adjusted in viscosity and hardness through a kneading step, the composition is uniformized to form a catalyst paste, and is used in step (2) described later.

  There are no particular restrictions on the details of the kneading step, and any means that can control the viscosity and hardness of the catalyst paste precursor to values suitable for molding, which will be described later, and can make the composition uniform. For example, any conventionally known means can be employed. For example, a twin-screw kneader, a continuous kneader, a double-arm kneader, a continuous screw kneader, a pressure kneader, a multi-blade kneader, a mixer (pug mixer, ribbon mixer) or the like is used.

In a preferred embodiment, the kneading process is performed in multiple stages (for example, two stages). Here, “the kneading step is performed in multiple stages” means that kneading and mixing operations under different conditions are continuously performed. In this case, “different conditions” include one or two or more of kneading strength, temperature, type of apparatus, apparatus rotation speed, apparatus internal pressure, throughput, and time during the kneading process. Preference is given to performing kneading and mixing operations in multiple stages (preferably two stages) using different apparatuses. For example, taking a two-stage kneading process as an example, the first kneading apparatus used in the first-stage kneading process is preferably a so-called kneader having a relatively high kneading strength. As the kneader, for example, one of a pressure type kneader, a twin-axis kneader, a continuous kneader, and a continuous screw kneader is preferably used. Further, as the second kneading apparatus used in the second stage kneading step, a so-called mixer having relatively low kneading strength is preferable. As the mixer, it is preferable to use one of a pug mixer, a ribbon mixer, a double-arm kneader, and a multi-blade kneader. Although a preferred embodiment in which a kneader and a mixer are used together has been described, it is preferable to use a kneader and a mixer together, as described above, using the kneader first, and using the mixer in the subsequent steps. More preferred. In other words, it is preferable to change so as to weaken the kneading strength in the middle of the kneading step, and it is more preferable to achieve such a change in kneading strength by changing the type of the apparatus such as a kneader → mixer. . By adopting such a configuration, there is an advantage that the viscosity and hardness of the catalyst paste precursor can be controlled to values suitable for molding and the composition can be made uniform. If the kneading strength is high, the object to be kneaded can be kneaded firmly and strongly, and the desired viscosity and hardness of the kneaded material can be obtained. On the other hand, if kneaded firmly and strongly in this step, the added inorganic fiber may be destroyed, so that the original fiber length may not be maintained. For this reason, it is more preferable to include a step of adding inorganic fibers after kneading with higher kneading strength and before kneading with lower kneading strength. Thereby, the abrasion strength of the catalyst can be further improved. Through the above-described kneading step, a catalyst paste is obtained in step (1). The hardness (measured with a soil hardness meter) of this catalyst paste is preferably Is 20 mm or more, more preferably 22 mm or more. The support strength of the catalyst paste is preferably 6.3 kg / cm ² or more, more preferably 8.5 kg / cm ² or more.

[Step (2)]
Step (2) is a step in which the catalyst paste obtained in step (1) is formed into a honeycomb and fired. Thereby, a honeycomb type denitration catalyst is obtained.

  The details of the molding process are not particularly limited, and any conventionally known means can be employed. For example, it may be formed into a honeycomb shape using an extrusion molding machine.

  The molded body thus obtained is then thoroughly dried at a temperature of about 50 to 120 ° C. Next, baking is performed at a temperature of about 300 to 750 ° C., preferably 400 to 650 ° C., more preferably 490 to 520 ° C. for 1 to 10 hours, preferably 3 to 10 hours. Thereby, a honeycomb-shaped denitration catalyst can be obtained.

No particular limitation on the characteristics of the denitration catalyst obtained, but for the specific surface area of the catalyst, ^{80 m} 2 / g or more ranges are preferred, and more preferably in the range of 80~250m ² / g. If the specific surface area of the catalyst is about 80 m ² / g or more, sufficient denitration performance can be obtained.

  The pore volume of the catalyst is such that the total pore volume is in the range of 0.25 to 0.5 mL / g, more preferably 0.3 to 0.5 mL / g. If the pore volume of the catalyst is 0.25 mL / g or more, sufficient denitration performance is obtained, and if it is 0.5 mL / g or less, the mechanical strength of the catalyst is sufficient and the wear resistance is also sufficient. Can be secured.

The obtained denitration catalyst contains at least one selected from the group consisting of vanadium, tungsten and molybdenum, which are the active ingredients added in step (1). The active ingredient content in the denitration catalyst is not particularly limited, but is preferably 0 to 20% by mass, more preferably 0 to 10% by mass in terms of oxides for each of vanadium, tungsten and molybdenum (however, The total is greater than 0% by weight). Moreover, although it does not restrict | limit especially about the total amount of active ingredients (The total amount when a several active ingredient is contained), Preferably it is 0-30 mass%, More preferably, it is 3-20 mass%, Preferably it is 5-10 mass%. The possibility that tungsten is contained as an active component in the denitration catalyst may be derived from the above-described first oxide (WO ₃ ) or in the form of a compound other than WO _3. However, in catalyst form, all are observed as WO _{3 and} the amount of tungsten as the active component is defined as the total amount.

  The denitration catalyst according to this embodiment is used for treating various exhaust gases. There are no particular restrictions on the composition of the exhaust gas, but it is emitted from heavy oil fired boilers, coal fired boilers, gas turbines, gas engines, diesel engines, thermal power plants, incineration facilities that process industrial and municipal wastes, and various industrial processes. Therefore, it is suitably used for the treatment of exhaust gas containing these nitrogen oxides.

In order to remove nitrogen oxides using the denitration catalyst according to this embodiment, the catalyst according to this embodiment is brought into contact with exhaust gas in the presence of a reducing agent such as ammonia or urea, so that nitrogen oxide in the exhaust gas is removed. It can be reduced and removed. The amount of ammonia is 0.3 to 1.5 times, preferably 0.5 to 1.2 times the equivalent amount capable of decomposing nitrogen oxides into nitrogen and water. If the amount of ammonia is 0.3 times or more than the equivalent amount capable of decomposing nitrogen oxides into nitrogen and water, the treatment efficiency of nitrogen oxides can be sufficiently secured, and if it is 1.5 times or less, unreacted It is possible to prevent adverse effects on the environment due to an increase in the residual amount of ammonia. Here, regarding the equivalent amount capable of decomposing nitrogen oxides into nitrogen and water, when the target substance is NO, ammonia is 1 mole with respect to 1 mole of NO, and when the target substance is NO ₂ , 1 mole of NO ₂ In contrast, ammonia is 1.33 to 2 mol. When urea is also used, urea acts as a double mole of ammonia, so that the mole amount is half of the ammonia amount.

  There is no particular limitation on the conditions for removing nitrogen oxides using the denitration catalyst according to the present embodiment, and the conditions can be implemented under conditions generally used for this type of reaction. Specifically, it may be determined as appropriate in consideration of the type and properties of the exhaust gas and the required removal rate.

The catalyst inlet gas temperature is preferably in the range of 100 to 600 ° C, more preferably 150 to 500 ° C, and even more preferably 200 to 450 ° C. Also, the space velocity at that time 100~200000hr ^-1 (STP) are preferable, 1000~100000hr ^-1 (STP), more preferably, more preferably 2000~50000hr ^-1 (STP) is good. In addition, the density | concentration of the nitrogen oxide in waste gas is 5-5000 ppm, Preferably it is 10-2000 ppm.

  Hereinafter, although embodiment of this invention is described in detail using an Example, the technical scope of this invention should not be limited and limited to the following Example. In addition, the flowchart corresponding to the manufacturing method of Example 9 is shown in FIG.

<Manufacture of honeycomb type catalyst>
Example 1
A honeycomb type denitration catalyst was obtained by the following method using TS mixed oxide as the first oxide.

  Specifically, first, 2.12 kg of ammonium paratungstate and 0.91 kg of monoethanolamine were mixed and dissolved in 2 L of water to prepare a uniform solution (liquid a). Further, 0.32 kg of ammonium metavanadate and 0.44 kg of oxalic acid were mixed and dissolved in 4 L of water to prepare a uniform solution (liquid b).

On the other hand, TS mixed oxide as a first oxide (powder of titanium-silicon mixed oxide containing 1.2% by mass of sulfur compound in terms of sulfur atom [mixing ratio is TiO ₂ : SiO ₂ = 88: 12 ( Mass ratio)]; average particle diameter 3 μm) 15.0 kg was weighed. Next, 5.0 kg of titanium oxide (average particle diameter 1 μm) as the second oxide was weighed. The weighed first oxide and second oxide are put into a kneader (the mixing ratio of the first oxide / second oxide is 75/25 (mass ratio)). Liquid and liquid b were added, and additional water was added and mixed together with inorganic fibers (glass wool) and a molding aid in an amount of 4% by mass with respect to 100% by mass of the catalyst to obtain a catalyst paste precursor. . This catalyst paste precursor was kneaded in a kneader until the hardness became appropriate (first kneading step). Thereafter, the kneaded product obtained in the first kneading step is transferred to a mixer, and an inorganic fiber (glass wool) in an amount of 4% by mass with respect to 100% by mass of the catalyst is further added, which is smaller than the kneader. By kneading with kneading strength, homogenization of the components was promoted (second kneading step).

The kneaded product obtained in the second kneading step was molded into an 80 mm square lattice (honeycomb) using an extruder. Subsequently, the obtained molded body was dried and then fired at 490 ° C. for 5 hours to obtain a honeycomb type denitration catalyst. The contents of V ₂ O ₅ and WO _{3 in} the obtained catalyst were 1.0% by mass and 7.5% by mass, respectively. Moreover, the equivalent diameter of the through-hole of the obtained honeycomb type denitration catalyst was 6 mm, the cell thickness was 1.0 mm, and the specific surface area was 100 m ² / g. The water content in the catalyst paste precursor (the total amount of water used for the liquid a, the water used for the liquid b and the additional water added during the kneading) is the first oxide and the second oxide. The total mass was 475 g.

(Example 2)
The content of water in the catalyst paste precursor (the total amount of the water used for the liquid a, the water used for the liquid b and the additional water added during the kneading) is the sum of the first oxide and the second oxide. A honeycomb type denitration catalyst was obtained in the same manner as in Example 1 except that the amount was 500 g per mass.

(Example 3)
The content of water in the catalyst paste precursor (the total amount of the water used for the liquid a, the water used for the liquid b and the additional water added during the kneading) is the sum of the first oxide and the second oxide. A honeycomb type denitration catalyst was obtained by the same method as in Example 1 except that the amount was 525 g per mass.

(Comparative Example 1)
The content of water in the catalyst paste precursor (the total amount of the water used for the liquid a, the water used for the liquid b and the additional water added during the kneading) is the sum of the first oxide and the second oxide. A honeycomb type denitration catalyst was obtained by the same method as in Example 1 except that the amount was 400 g per mass.

(Comparative Example 2)
The content of water in the catalyst paste precursor (the total amount of the water used for the liquid a, the water used for the liquid b and the additional water added during the kneading) is the sum of the first oxide and the second oxide. A honeycomb type denitration catalyst was obtained by the same method as in Example 1 except that the amount was 650 g per mass.

(Comparative Example 3)
20.0 kg of the first oxide (TS mixed oxide) was used, and the second oxide (titanium oxide) was not used (the mixing ratio of the first oxide / second oxide was 100/0. Except for (mass ratio), a honeycomb type denitration catalyst was obtained in the same manner as in Example 2 described above.

Example 4
19.0 kg of the first oxide (TS mixed oxide) and 1.0 kg of the second oxide (titanium oxide) were used (the first oxide / second oxide mixing ratio was 95). The honeycomb type denitration catalyst was obtained by the same method as in Example 2 described above except that the ratio was / 5 (mass ratio).

(Example 5)
18.0 kg of the first oxide (TS mixed oxide) was used, and 2.0 kg of the second oxide (titanium oxide) was used (the first oxide / second oxide mixing ratio was 90). / 10 (mass ratio)), a honeycomb type denitration catalyst was obtained by the same method as in Example 2 described above.

(Example 6)
14.0 kg of the first oxide (TS mixed oxide) was used, and 6.0 kg of the second oxide (titanium oxide) was used (the first oxide / second oxide mixing ratio was 70). / 30 (mass ratio)), a honeycomb type denitration catalyst was obtained by the same method as in Example 2 described above.

(Comparative Example 4)
10.0 kg of the first oxide (TS mixed oxide) and 10.0 kg of the second oxide (titanium oxide) were used (the first oxide / second oxide mixing ratio was 50). / 50 (mass ratio)), a honeycomb type denitration catalyst was obtained by the same method as in Example 2 described above.

(Example 7)
Using a TSW mixed oxide as the first oxide, a honeycomb type denitration catalyst was obtained by the following method.

  Specifically, first, 1.75 kg of ammonium paratungstate and 0.75 kg of monoethanolamine were mixed and dissolved in 2 L of water to prepare a uniform solution (liquid a). Further, 0.32 kg of ammonium metavanadate and 0.43 kg of oxalic acid were mixed and dissolved in 4 L of water to prepare a uniform solution (liquid b).

On the other hand, TSW mixed oxide which is the first oxide (powder of titanium-silicon-tungsten mixed oxide containing 1.2% by mass of sulfur compound in terms of sulfur atom [mixing ratio is TiO ₂ : SiO ₂ : WO ₃ = 95: 3: 2 (mass ratio); average particle diameter 25 μm) 15.0 kg was weighed. Next, 5.0 kg of titanium oxide (average particle diameter 1 μm) as the second oxide was weighed. The weighed first oxide and second oxide are put into a kneader (the mixing ratio of the first oxide / second oxide is 75/25 (mass ratio)). Liquid and liquid b were added, and additional water was added and mixed together with inorganic fibers (glass wool) and a molding aid in an amount of 4% by mass with respect to 100% by mass of the catalyst to obtain a catalyst paste precursor. . This catalyst paste precursor was kneaded in a kneader until the hardness became appropriate (first kneading step). Thereafter, the kneaded product obtained in the first kneading step is transferred to a mixer, and an inorganic fiber (glass wool) in an amount of 4% by mass with respect to 100% by mass of the catalyst is further added, which is smaller than the kneader. By kneading with kneading strength, homogenization of the components was promoted (second kneading step).

The kneaded product obtained in the second kneading step was molded into an 80 mm square lattice (honeycomb) using an extruder. Subsequently, the obtained molded body was dried and then fired at 490 ° C. for 5 hours to obtain a honeycomb type denitration catalyst. The contents of V ₂ O ₅ and WO _{3 in} the obtained catalyst were 1.0% by mass and 7.5% by mass, respectively. In addition, the equivalent diameter of the through hole of the obtained honeycomb type denitration catalyst was 6 mm, the cell thickness was 1.0 mm, and the specific surface area was 97 m ² / g. The water content in the catalyst paste precursor (the total amount of water used for the liquid a, the water used for the liquid b and the additional water added during the kneading) is the first oxide and the second oxide. The total mass was 500 g.

(Example 8)
After obtaining a TS composite oxide as the first oxide by the following method, a honeycomb type denitration catalyst was obtained using this.

[Preparation of first oxide (TS composite oxide)]
Specifically, first, a TS composite oxide (TiO ₂ —SiO ₂ composite oxide powder) as the first oxide was prepared by the method described below.

715 L of aqueous ammonia (NH ₃ -25%) was added to 1000 L of water, and 44 kg of a 30% by mass silica sol solution was added thereto. To the obtained aqueous solution, a sulfuric acid aqueous solution of titanyl sulfate (TiOSO ₄ [TiO ₂ equivalent] 250 g / L, H ₂ SO ₄ −1100 g / L) 401 L diluted with 800 L of water was gradually diluted with stirring with a titanium-containing sulfuric acid aqueous solution. To form a coprecipitated gel. Furthermore, it was left to stand for 40 hours as it was. The TiO ₂ —SiO ₂ gel thus obtained is filtered, washed with water, dried, and then fired at 550 ° C. for 5 hours in an air atmosphere to form the first oxide (TiO ₂ —SiO _{2). 2} composite oxide powder). The composition of the obtained first oxide was TiO ₂ : SiO ₂ = 88: 12 in terms of mass ratio as an oxide. The amount of the sulfur compound contained in the first oxide was 1.2% by mass in terms of sulfur atom. The average particle size of the first oxide was 20 μm.

[Manufacture of honeycomb type catalyst]
In 2 L of water, 2.12 kg of ammonium paratungstate and 0.91 kg of monoethanolamine were mixed and dissolved to prepare a uniform solution (liquid a). Further, 0.32 kg of ammonium metavanadate and 0.44 kg of oxalic acid were mixed and dissolved in 4 L of water to prepare a uniform solution (liquid b).

  On the other hand, 15.0 kg of the TS composite oxide (average particle size 20 μm) which was the first oxide prepared above was weighed. Next, 5.0 kg of titanium oxide (average particle diameter 1 μm) as the second oxide was weighed. The weighed first oxide and second oxide are put into a kneader (the mixing ratio of the first oxide / second oxide is 75/25 (mass ratio)). Liquid and liquid b were added, and additional water was added and mixed together with inorganic fibers (glass wool) and a molding aid in an amount of 4% by mass with respect to 100% by mass of the catalyst to obtain a catalyst paste precursor. . This catalyst paste precursor was kneaded in a kneader until the hardness became appropriate (first kneading step). Thereafter, the kneaded product obtained in the first kneading step is transferred to a mixer, and an inorganic fiber (glass wool) in an amount of 4% by mass with respect to 100% by mass of the catalyst is further added, which is smaller than the kneader. By kneading with kneading strength, homogenization of the components was promoted (second kneading step).

The kneaded product obtained in the second kneading step was molded into an 80 mm square lattice (honeycomb) using an extruder. Subsequently, the obtained molded body was dried and then fired at 490 ° C. for 5 hours to obtain a honeycomb type denitration catalyst. The contents of V ₂ O ₅ and WO _{3 in} the obtained catalyst were 1.0% by mass and 7.5% by mass, respectively. Moreover, the equivalent diameter of the through holes of the obtained honeycomb type denitration catalyst was 6 mm, the cell thickness was 1.0 mm, and the specific surface area was 115 m ² / g. The water content in the catalyst paste precursor (the total amount of water used for the liquid a, the water used for the liquid b and the additional water added during the kneading) is the first oxide and the second oxide. The total mass was 500 g.

Example 9
After obtaining the TSW composite oxide as the first oxide by the following method, a honeycomb type denitration catalyst was obtained using this.

[Preparation of first oxide (TSW composite oxide)]
Specifically, first, a TSW composite oxide (TiO ₂ —SiO ₂ —WO ₃ composite oxide powder) as a first oxide was prepared by the method described below.

715 L of aqueous ammonia (NH ₃ -25%) was added to 1000 L of water, and 19 kg of a 30% by mass silica sol solution was added thereto. Then, 1 kg of monoethanolamine (MEA) was added to 5 L of water separately prepared, 2.6 kg of ammonium paratungstate was mixed from above, and heated to about 60 ° C. to dissolve ammonium paratungstate. The liquid was added. A titanium-containing sulfuric acid aqueous solution obtained by adding 421 L of sulfuric acid aqueous solution of titanyl sulfate (TiOSO ₄ [equivalent to TiO ₂ ] 250 g / L, H ₂ SO ₄ −1100 g / L) to 800 L of water was gradually added to the obtained aqueous solution with stirring. To form a coprecipitated gel. Furthermore, it was left to stand for 40 hours as it was. The TiO ₂ —SiO ₂ —WO ₃ gel thus obtained is filtered, washed with water, dried, and then calcined at 550 ° C. for 5 hours in an air atmosphere to obtain the first oxide (TiO 2 to obtain a powder) of the composite oxide of ₂ -SiO ₂ -WO _3. The composition of the obtained first oxide was TiO ₂ : SiO ₂ : WO ₃ = 95: 3: 2 in terms of mass ratio as an oxide. The amount of the sulfur compound contained in the first oxide was 1.2% by mass in terms of sulfur atom. The average particle diameter of the first oxide was 25 μm.

[Manufacture of honeycomb type catalyst]
To 2 L of water, 1.75 kg of ammonium paratungstate and 0.75 kg of monoethanolamine were mixed and dissolved to prepare a uniform solution (liquid a). Further, 0.32 kg of ammonium metavanadate and 0.43 kg of oxalic acid were mixed and dissolved in 4 L of water to prepare a uniform solution (liquid b).

  On the other hand, 15.0 kg of the TSW composite oxide (average particle size 25 μm), which was the first oxide prepared above, was weighed. Next, 5.0 kg of titanium oxide (average particle diameter 1 μm) as the second oxide was weighed. The weighed first oxide and second oxide are put into a kneader (the mixing ratio of the first oxide / second oxide is 75/25 (mass ratio)). Liquid and liquid b were added, and additional water was added and mixed together with inorganic fibers (glass wool) and a molding aid in an amount of 4% by mass with respect to 100% by mass of the catalyst to obtain a catalyst paste precursor. . This catalyst paste precursor was kneaded in a kneader until the hardness became appropriate (first kneading step). Thereafter, the kneaded product obtained in the first kneading step is transferred to a mixer, and an inorganic fiber (glass wool) in an amount of 4% by mass with respect to 100% by mass of the catalyst is further added, which is smaller than the kneader. By kneading with kneading strength, homogenization of the components was promoted (second kneading step).

The kneaded product obtained in the second kneading step was molded into an 80 mm square lattice (honeycomb) using an extruder. Subsequently, the obtained molded body was dried and then fired at 490 ° C. for 5 hours to obtain a honeycomb type denitration catalyst. The contents of V ₂ O ₅ and WO _{3 in} the obtained catalyst were 1.0% by mass and 7.5% by mass, respectively. Moreover, the equivalent diameter of the through-hole of the obtained honeycomb type denitration catalyst was 6 mm, the cell thickness was 1.0 mm, and the specific surface area was 112 m ² / g. The water content in the catalyst paste precursor (the total amount of water used for the liquid a, the water used for the liquid b and the additional water added during the kneading) is the first oxide and the second oxide. The total mass was 500 g.

(Example 10)
The amount of inorganic fibers (glass wool) added to the kneader in the first kneading step is changed to an amount of 8% by mass with respect to 100% by mass of the catalyst, and the inorganic fibers added to the mixer in the second kneading step The implementation described above, except that the amount of (glass wool) was changed to 0% by mass with respect to 100% by mass of the catalyst (that is, no inorganic fiber (glass wool) was added to the mixer). A honeycomb type denitration catalyst was obtained in the same manner as in Example 2.

[Evaluation of honeycomb type denitration catalyst]
Using the honeycomb-type denitration catalysts obtained in the above Examples and Comparative Examples, the wear resistance (wear rate) and the denitration performance (denitration rate) of the catalyst were evaluated under the following conditions. The results are shown in Table 2 below. Table 2 shows the average particle diameter values of the first oxide and the second oxide measured by the laser diffraction scattering method, and the pore volume of the honeycomb type denitration catalyst measured by the mercury intrusion method. The value of is also described.

(Evaluation of wear resistance (measurement of wear rate))
A honeycomb-type denitration catalyst was cut into a size of 9 cells × 9 cells × 100 mm in length and used as a sample for wear rate measurement. A forced wear test was conducted by introducing air containing 38 g / m ³ of dredged sand into the through hole of this sample at a normal gas flow rate of 16 m / s (per catalyst cross section) for 2 hours. The rate was calculated. In addition, it means that it is excellent in abrasion resistance, so that the value of an abrasion rate is small.

Abrasion rate (%) = ([catalyst mass before test−catalyst mass after test) / catalyst mass before test] × 100
(Denitration rate measurement)
The honeycomb type denitration catalyst was cut into a size of 3 cells × 3 cells × 306 mm and filled into a stainless steel reaction tube. A synthesis gas having the composition shown in Table 1 below was introduced into the reaction tube. And the NOx density | concentration of reaction tube inlet gas and outlet gas was measured with the chemical optical NOx meter, and the denitration rate was computed according to the following formula. In addition, it means that it is excellent in denitration performance, so that the value of denitration rate is large.

  Denitration rate (%) = [(inlet NOx concentration−outlet NOx concentration) / inlet NOx concentration] × 100

  From the results shown in Table 2, in Comparative Example 1 in which the amount of water added is too small and Comparative Example 4 in which the amount of the second oxide (titanium oxide) is too large, wear resistance is excellent, but sufficient denitration performance is achieved. Haven't been able to get. On the other hand, in Comparative Example 2 in which the amount of water added is too large and in Comparative Example 3 in which the second oxide (titanium oxide) is not blended, although sufficient denitration performance is obtained, sufficient wear resistance can be obtained. Absent.

  On the other hand, when a catalyst paste precursor containing a predetermined first oxide and titanium oxide (second oxide) is kneaded and then formed into a honeycomb shape, the above oxide is produced. Is blended at a predetermined mass ratio, and the amount of water added to the catalyst paste precursor is controlled to a value within a predetermined range, thereby minimizing a decrease in denitration performance and having excellent wear resistance. It can be seen that a mold denitration catalyst can be obtained.

Claims (7)

Titanium oxide, mixed oxide and / or composite oxide of titanium-silicon, mixed oxide and / or composite oxide of titanium-tungsten, and mixed oxide and / or composite oxide of titanium-silicon-tungsten A catalyst comprising: a first oxide selected from the group; a second oxide made of titanium oxide; at least one active ingredient selected from the group consisting of vanadium, tungsten and molybdenum; and water. Kneading a paste precursor to obtain a catalyst paste, and
A method for producing a honeycomb-type denitration catalyst, comprising forming the catalyst paste into a honeycomb shape and firing the catalyst paste,
The water content in the catalyst paste precursor is 450 to 550 g / kg per total mass of the first oxide and the second oxide, and
The content of the second oxide in the catalyst paste precursor is 2 to 40% by mass with respect to the total mass of the first oxide and the second oxide, Manufacturing method of honeycomb type denitration catalyst.   The first oxide according to claim 1, wherein the first oxide is selected from the group consisting of a titanium-silicon mixed oxide and / or composite oxide and a titanium-silicon-tungsten mixed oxide and / or composite oxide. A method for producing the honeycomb-type denitration catalyst as described.   The method for producing a honeycomb type denitration catalyst according to claim 1 or 2, wherein the kneading is performed in two or more stages using different apparatuses.   The content of the second oxide in the catalyst paste precursor is 5 to 25% by mass with respect to the total mass of the first oxide and the second oxide. A method for producing a honeycomb-type denitration catalyst according to any one of the above.   The manufacturing method of the honeycomb type denitration catalyst according to any one of claims 1 to 4, wherein an average particle diameter of the second oxide is 0.5 to 3 µm.   The manufacturing method of the honeycomb type denitration catalyst according to any one of claims 1 to 5, wherein an average particle diameter of the first oxide is 1 to 50 µm.   The manufacturing method of the honeycomb type denitration catalyst according to any one of claims 1 to 6, wherein the firing is performed at a temperature of 490 to 520 ° C for 3 to 10 hours.