KR20240034316A - Denitrification catalyst and its manufacturing method - Google Patents

Abstract

The present invention relates to a denitrification catalyst and a method for manufacturing the same, which includes a base catalyst containing tungsten oxide, cerium oxide and titanium oxide, and vanadium and lanthanum are doped inside the crystal structure of the base catalyst to greatly improve sulfur dioxide durability. The nitrogen oxide conversion rate can be maintained at more than 80% of the initial level even over a long period of time.

Description

Denitrification catalyst and its manufacturing method {DENITRIFICATION CATALYST AND ITS MANUFACTURING METHOD}

The present invention relates to a denitrification catalyst and a method for manufacturing the same, and more specifically, to a denitrification catalyst that can decompose ammonium sulfate produced in a coal-fired power plant at low temperature and has excellent durability against sulfur dioxide and a method for manufacturing the same.

Nitrogen oxides ( _NO A lot of research is being done to reduce it.

In particular, nitrogen oxides are generated from stationary sources such as power plants or incinerators or automobiles, and act as one of the causes of air pollution.

In addition, a method of removing nitrogen compounds emitted from air pollution is nitrogen monoxide conversion using ammonia, etc. as a reducing agent, and titanium dioxide (TiO ₂ ) carrier and vanadium oxide (V ₂ O ₅ ) as active catalyst components. Catalysts are widely used.

However, no catalyst has been disclosed that shows excellent activity at low temperatures below 300 degrees Celsius, and most fuels except liquefied natural gas (LNG) contain sulfur components, and most of them produce sulfur dioxide (SO ₂ ) during the combustion process. is discharged as

Conventional denitrification catalysts such as vanadium/titanium dioxide react with sulfur dioxide present in exhaust gas and ammonia, a reducing agent, at 250°C to 400°C to produce ammonium sulfate salt (NH ₄ HSO ₄ , (NH ₄ ) ₂ SO ₄ ) as shown in Scheme 1 below. forms.

[Scheme 1]

2SO ₂ + O ₂ → 2SO ₃

NH ₃ + SO ₃ + H ₂ O → NH ₄ HSO ₄

2NH ₃ + SO ₃ + H ₂ O → (NH ₄ ) ₂ SO ₄

Therefore, ammonium sulfate is deposited on the catalyst surface, reducing the activity of the catalyst and causing corrosion and clogging of the lower reactor equipment, so it is necessary to develop a catalyst with excellent durability against sulfur dioxide.

Korean Patent Publication No. 0456748

The present invention was created to improve the conventional problems as described above, and is applied to an ammonia-based selective catalytic reduction (SCR) system for removing nitrogen oxides contained in exhaust gases generated from coal-fired power plants. The purpose is to provide a denitrification catalyst and a manufacturing method that can increase durability against sulfur dioxide poisoning.

In order to achieve the above-described object, the denitrification catalyst according to the present invention is formed by supporting vanadium and lanthanum on a pre-fired body made from tungsten oxide, cerium oxide, and titanium oxide.

The denitrification catalyst may include a CeVO ₄ crystal phase therein.

The CeVO ₄ crystal phase may be connected to vanadium oxide in an oligomeric form.

The amount of trivalent cerium contained within the CeVO ₄ crystal phase may be 50 atomic% or less compared to the total cerium atoms contained in the entire catalyst.

The amount of trivalent cerium and tetravalent cerium contained within the CeVO ₄ crystal phase may be between 60 atomic% and 80 atomic% compared to the total cerium atoms contained in the entire catalyst.

The denitrification catalyst may have a nitrogen oxide conversion rate of 70% or more at a temperature of 250°C or more and 400°C or less.

The denitrification catalyst may have a nitrogen oxide conversion rate of 80% or more and less than 90% of the initial level after 200 hours at 250°C or more and 400°C or less.

In addition, in order to achieve the above-described object, the method for producing a denitrification catalyst according to the present invention involves mixing 100 parts by weight of titanium oxide to prepare a premix by mixing 5 parts by weight of a tungsten precursor and 5 parts by weight of a cerium precursor. step; A pre-fired body firing step of producing a pre-fired body by firing the premix at a temperature of 550°C or more and 650°C or less; A main reactor mixing step of preparing a main mixture by mixing 1.5 parts by weight of a vanadium precursor and 1 part by weight of a lanthanum precursor with respect to 100 parts by weight of the precalcined body; And a main body sintering step of producing a denitrification catalyst by sintering the main mixture at a temperature of 450°C or more and 550°C or less.

The titanium oxide may have an anatase crystal phase.

The vanadium precursor may be metavanadate (NH ₄ VO ₃ ).

The lanthanum precursor may be lanthanum nitrate (LaN ₃ O ₉ ).

As described above, according to the nitrogen removal catalyst and its manufacturing method according to the present invention, when the exhaust gas discharged from a coal-fired power plant contains sulfur dioxide, the formation of ammonium sulfate salt is suppressed, the nitrogen oxide removal ability is maintained stably, and the sulfur dioxide durability is maintained. This has a dramatic improvement effect.

Figure 1 is a diagram showing the state in which vanadium oxide in an isolated form is formed on the surface of titanium dioxide in a denitrification catalyst according to a comparative example of the present invention.
Figure 2 is a diagram showing the formation of oligomeric vanadium oxide on the surface of titanium dioxide in a denitrification catalyst according to an embodiment of the present invention.
Figure 3 is a graph showing the nitrogen oxide conversion rate (black - pure water, red - ammonium sulfate added) according to temperature in the denitrification catalyst according to an embodiment of the present invention.
Figure 4 is a graph showing the nitrogen oxide conversion rate (black - pure water, red - ammonium sulfate added) according to temperature in the denitrification catalyst according to the comparative example of the present invention.
Figure 5 is a graph showing the change in nitrogen oxide conversion rate under atmospheric conditions in which sulfur dioxide (SO ₂ ) flows into the denitrification catalyst according to the Examples and Comparative Examples of the present invention.
Figure 6 is a graph showing the oxygen transfer capacity temperature of the denitrification catalyst according to the examples and comparative examples of the present invention through hydrogen-temperature controlled reduction (H2-TPR) measurement.
Figure 7 is a graph showing the structure of vanadium located on the surface of the denitrification catalyst according to the examples and comparative examples of the present invention using Raman spectroscopy.
Figure 8 is a graph showing the desorption temperature and area of sulfur dioxide (SO ₂ ) adsorbed on the surface of the denitrification catalyst according to the examples and comparative examples of the present invention.
Figure 9 is a flowchart showing the manufacturing method of the NOx removal catalyst according to the present invention.

Hereinafter, preferred embodiments of the present invention will be described in detail with reference to the attached drawings.

Since the present invention can make various changes and have various embodiments, specific embodiments will be illustrated in the drawings and described in detail in the detailed description. This is not intended to limit the present invention to specific embodiments, and should be interpreted as including all changes, equivalents, and substitutes included in the spirit and technical scope of the present invention.

In describing the present invention, terms such as first and second may be used to describe various components, but the components may not be limited by the terms. The above terms are solely for the purpose of distinguishing one component from another. For example, a first component may be named a second component, and similarly, the second component may also be named a first component without departing from the scope of the present invention.

The term “and/or” may include any of a plurality of related stated items or a combination of a plurality of related stated items.

When a component is said to be "connected" or "connected" to another component, it means that it may be directly connected to or connected to that other component, but that other components may also exist in between. It can be understood. On the other hand, when a component is referred to as being “directly connected” or “directly connected” to another component, it can be understood that there are no other components in between.

The terms used in this application are only used to describe specific embodiments and are not intended to limit the invention. Singular expressions may include plural expressions, unless the context clearly indicates otherwise.

In this application, terms such as “comprise” or “have” are intended to designate the presence of features, numbers, steps, operations, components, parts, or combinations thereof described in the specification, and one or more other features It can be understood that it does not exclude in advance the possibility of the existence or addition of elements, numbers, steps, operations, components, parts, or combinations thereof.

Unless otherwise defined, all terms used herein, including technical or scientific terms, may have the same meaning as commonly understood by a person of ordinary skill in the technical field to which the present invention pertains. Terms defined in commonly used dictionaries can be interpreted as having meanings consistent with the meanings they have in the context of related technologies, and unless clearly defined in this application, are interpreted as having an ideal or excessively formal meaning. It may not work.

In addition, the following examples are provided to provide a more complete explanation to those with average knowledge in the art, and the shapes and sizes of elements in the drawings may be exaggerated for clearer explanation.

The present invention provides a catalyst with excellent activity and durability at low temperature conditions in order to respond to the variable load characteristics of coal-fired power plants and solve the problem of denitrification catalysts being poisoned by ammonium sulfate (ABS).

Referring to FIG. 1, a denitrification catalyst according to an embodiment of the present invention is formed by supporting vanadium and lanthanum on a precalcined body made from tungsten oxide, cerium oxide, and titanium oxide.

In detail, the denitrification catalyst may exist in a state in which vanadium and lanthanum are dispersed in a substrate containing tungsten, cerium, and titanium oxide or may be supported on the surface of the substrate.

Inside the denitrification catalyst, a CeVO ₄ structure is formed in which vanadium (V) and cerium (Ce) atoms are combined with oxygen, and can exist in a separate state from tungsten oxide, cerium oxide, and titanium oxide.

When the CeVO ₄ structure is formed, it can be seen that the oxygen transfer ability is improved during the decomposition process of nitrogen oxides.

In addition, as shown in FIG. 2, vanadium oxide (VOX) exists in an oligomeric structure with the CeVO ₄ crystal phase on the surface of titanium oxide, so it can be used under low temperature conditions (compared to existing in an isolated structure as shown in FIG. 1). At 250~400℃), oxygen transfer ability is excellent and denitrification performance is improved.

The prefired body contains 5 parts by weight of tungsten oxide and 5 parts by weight of cerium oxide based on 100 parts by weight of titanium oxide.

Additionally, the denitrification catalyst includes 1.5 parts by weight of vanadium and 1 part by weight of lanthanum based on 100 parts by weight of the precalcined body.

The denitrification catalyst uses titanium oxide (TiO ₂ ) having an anatase phase as a support, and the titanium oxide is most preferably a material having a surface area of 80 m ² /g or more and 100 m ² /g or less.

The denitrification catalyst includes a titanium oxide support, ammonium metatungstate ((NH ₄ )6H ₂ W ₁₂ O ₄₀ *H ₂ O), which is a tungsten oxide precursor, and cerium nitrate hexahydrate, which is a cerium oxide precursor. It is manufactured by mixing Ce(NO ₃ ) ₃ ·6H ₂ O) and then going through a primary calcination process.

The amount of trivalent cerium contained within the CeVO ₄ crystal phase is less than 50 atomic% compared to the total cerium atoms contained in the entire denitrification catalyst.

When the trivalent cerium contained within the CeVO ₄ crystal phase exceeds 50 atomic% compared to the total atoms of cerium contained in the denitrification catalyst, cerium oxide is excessively present on the surface of titanium oxide, forming nitrogen oxide ( _NO decomposition ability decreases.

The amount of trivalent cerium and tetravalent cerium contained within the CeVO ₄ crystal phase is between 60 atomic% and 80 atomic% compared to the total cerium atoms contained in the entire denitrification catalyst.

When the trivalent cerium and tetravalent cerium contained within the CeVO ₄ crystal phase exceed 80 atomic% compared to the total atoms of cerium contained in the denitrification catalyst, cerium oxide is excessively present on the surface of titanium oxide, forming nitrogen oxide. The decomposition ability of ( _NO

On the other hand, when the amount of trivalent cerium and tetravalent cerium contained within the CeVO ₄ crystal phase is less than 60 atomic% compared to the total atoms of cerium contained in the denitrification catalyst, sulfur dioxide (SO ₂ ) reacts with ammonia to form ammonium sulfate salt. A problem arises in which activity is reduced due to poisoning.

The nitrogen oxide denitrification catalyst has a nitrogen oxide conversion rate of 70% to 100% at 250°C or higher and 400°C or lower.

If the nitrogen oxide conversion rate of the denitrification catalyst is less than 70% at 250°C or higher and 400°C or lower, nitrogen oxides are not sufficiently removed, causing air pollution.

If the nitrogen oxide conversion process of the denitrification catalyst is performed below 250°C, the time required for the reaction increases, reducing economic efficiency, and if performed above 400°C, there is a problem in that a large amount of energy is consumed at high temperature.

In addition, the nitrogen oxide conversion rate of the nitrogen oxide denitrification catalyst after 200 hours at 250°C or more and 400°C or less is 80% or more and 90% or less compared to the initial level.

If the nitrogen oxide conversion rate of the denitrification catalyst is less than 80% of the initial level after 200 hours at 250°C or higher and 400°C or lower, the denitrification catalyst continues to deteriorate over time, making it difficult to use for a long time and sufficient decomposition of nitrogen oxides is not achieved. I don't lose.

In addition, the method for producing a denitrification catalyst according to another embodiment of the present invention includes a pre-fired material mixing step of preparing a premix by mixing 5 parts by weight of a tungsten precursor and 5 parts by weight of a cerium precursor with 100 parts by weight of titanium oxide, and the preliminary A pre-fired body firing step of producing a pre-fired body by firing the mixture at a temperature of 550°C or more and 650°C or less for a time of 3 hours or more and 5 hours or less, and 1.5 parts by weight of a vanadium precursor based on 100 parts by weight of the prefired body, and A main substance mixing step of mixing 1 part by weight of a lanthanum precursor to prepare a main mixture, and calcining the main mixture at a temperature of 450 ℃ or more and 550 ℃ for 3 hours or more and 5 hours or less to produce a denitrification catalyst. Includes steps.

In the pre-fired body mixing step, 5 parts by weight of tungsten precursor and 5 parts by weight of cerium precursor are mixed with 100 parts by weight of titanium oxide, and generally known techniques such as ball milling can be used, so the detailed mixing process is omitted.

If the pre-fired body sintering step is performed below 550°C, the titanium oxide, the tungsten precursor, and the cerium precursor may not sufficiently interdiffuse, so that titanium oxide, tungsten oxide, and cerium oxide may exist unevenly.

When the pre-calcined body calcination step is performed above 650° C., a problem occurs in which a portion of the titanium oxide is melted and the catalyst surface area is reduced.

If the pre-fired body calcination step is performed for less than 3 hours, the titanium oxide, the tungsten precursor, and the cerium precursor may not sufficiently react, resulting in residues. If the precalciner calcination step is performed for more than 5 hours, the titanium oxide may There is a problem in that the hole size decreases and the catalyst surface area decreases.

In the main calcination step, 1.5 parts by weight of vanadium precursor and 1 part by weight of lanthanum precursor are mixed with 100 parts by weight of precalcinant. Since generally known techniques such as ball milling can be used, the detailed mixing process is omitted.

When the main calcination step is carried out below 450°C, the pre-calciner, the vanadium precursor, and the lanthanum precursor do not sufficiently mutually diffuse, resulting in non-uniform formation of the pre-calciner, vanadium oxide, lanthanum oxide, titanium oxide, tungsten oxide, and cerium oxide. This can exist.

When the main calcination step is carried out above 550°C, a problem occurs in which a portion of the pre-calcined body is melted and the catalyst surface area is reduced.

If the main calcination step is carried out for less than 3 hours, the pre-calciner, the vanadium precursor and the lanthanum precursor may not react sufficiently, and residues may be generated. If the main calcination step is carried out for more than 5 hours, residue may be generated in the catalyst. There is a problem in that the hole size decreases and the catalyst surface area decreases.

The titanium oxide may have an anatase crystal phase.

The titanium oxide is rutile, not anatase. In the case of having a brookite crystal phase, there is a problem in that the catalytic activity for reducing nitrogen oxides is lower than that in the case of an anatase crystal phase.

The vanadium precursor may be metavanadate (NH ₄ VO ₃ ).

The lanthanum precursor may be lanthanum nitrate (LaN ₃ O ₉ ).

Example

Hereinafter, the configuration and operation of the present invention will be described in more detail through preferred embodiments of the present invention. However, this is presented as a preferred example of the present invention and should not be construed as limiting the present invention in any way.

Any information not described here can be technically inferred by anyone skilled in the art, so description thereof will be omitted.

1. Preparation of specimens

Example

The samples used in the examples of the present invention and their manufacturing methods are as follows.

Based on 100 parts by weight of titanium oxide (TiO ₂ ), 5 parts by weight of ammonium metatungstate hydrate ((NH ₄ ) ₆ H ₂ W ₁₂ O ₄₀ *H ₂ O) as a tungsten precursor and cerium nitrate hexahydrate (Ce) as a cerium precursor. (NO ₃ ) ₃ * 6H ₂ O) 5 parts by weight were weighed and dissolved in distilled water heated to 60°C to prepare a tungsten precursor-cerium precursor aqueous solution, and then the tungsten precursor-cerium precursor aqueous solution was mixed with titanium oxide to form a slurry. It is manufactured with

Afterwards, moisture is removed under vacuum conditions through an evaporator, then dried in an oven at 103°C for over 24 hours to further remove moisture, and then first fired in an air atmosphere at 600°C in a sintering furnace for 4 hours to produce tungsten-cerium. /A pre-fired body composed of titania was prepared.

And, based on 100 parts by weight of the precalcined material, 1.5 parts by weight of ammonium metavanadate (NH ₄ VO ₃ ) as a vanadium precursor and 1.0 parts by weight of lanthanum nitrate hydrate (LaN ₃ O ₉ ) as a lanthanum precursor were measured and added to distilled water heated to 60°C. After dissolving in to prepare a vanadium precursor-lanthanum precursor aqueous solution, the vanadium precursor-lanthanum precursor aqueous solution is mixed with the pre-calcined body to prepare a slurry form.

Afterwards, moisture is removed under vacuum conditions through an evaporator, then dried in an oven at 103°C for more than 24 hours to further remove moisture, and then first fired in an air atmosphere at 500°C in a kiln for 4 hours to produce vanadium-lanthanum. A denitrification catalyst consisting of /tungsten-cerium/titania was manufactured.

Comparative example

The manufacturing method of the example was performed in the same manner, except that 1.5 parts by weight of ammonium metavanadate (NH ₄ VO ₃ ) as a vanadium precursor was not mixed based on 100 parts by weight of the precalcined body.

2. Performance evaluation

ABS response activity recovery rate

In order to confirm the ammonium sulfate (ABS) decomposition characteristics of the denitrification catalysts prepared in the above-mentioned examples and comparative examples, ammonium sulfate (ABS) was added to each catalyst and the recovery of reaction activity was compared with the fresh catalyst as shown in Figures 3 and 3. Figure 4 was confirmed.

Nitrogen oxides (NOx) supplied to the experiment are 800 ppm, oxygen (O ₂ ) is 8% by volume, moisture (H ₂ O) is 6% by mass, ash (Ash) is 5% by mass, and space velocity (processed gas amount (Nm ³ / h)/catalyst amount (m ³ )) was maintained at 120,000 hr ^-1 and the temperature was raised from 250°C to 400°C.

Referring to Figure 3, the denitrification catalyst containing ammonium sulfate (ABS) of the example showed an activity of 59% at 300°C, a difference of 37% from the initial activity of 96%, and referring to Figure 4, the ammonium sulfate (ABS) catalyst of the comparative example showed an activity of 59% at 300°C. The denitrification catalyst with the addition of (ABS) showed an activity of 51% at 300°C, a difference of 45% from the initial activity of 96%.

In addition, at 325°C, the denitrification catalyst added with ammonium sulfate (ABS) of the example showed an activity of 88%, a difference of 11% from the initial activity of 99%, and the denitrification catalyst added with ammonium sulfate (ABS) of the comparative example showed an activity of 325%. The activity was 76% at ℃, showing a difference of 22% from the initial activity of 98%.

Therefore, with the addition of lanthanum (La), there was a 10% difference in activity recovery at 325°C, and the initial activity was completely recovered at 350°C.

It can be seen that the Example shows better recovery characteristics of denitrification efficiency from ABS than the Comparative Example in the exhaust gas temperature range of about 300 to 325°C, which occurs when a coal-fired power plant is operated flexibly.

SO ₂ Durability evaluation

The nitrogen oxide removal characteristics of the denitrification catalyst prepared in the above-described examples and comparative examples were evaluated under conditions in which sulfur dioxide (SO ₂ ) was injected.

_The gases supplied in the comparative experiment were 800 _ppm nitrogen _oxide ( _NO The process was conducted with the space velocity (SV) maintained at 120,000hr ^-1 .

Durability against sulfur dioxide (SO ₂ ) was expressed as K/K ₀ by dividing the nitrogen oxide removal rate (K) according to the reaction time by the initial nitrogen oxide removal rate (K ₀ ) when gas began to be injected.

Referring to Figure 5, in the comparative example, it took 85 hours for K/K ₀ to decrease to 0.8, while in the example, K/K ₀ was 0.84 even after 200 hours due to the addition of lanthanum (La).

Therefore, it was confirmed that the durability of the example was improved by more than 2.3 times compared to the comparative example.

Based on the above results, the addition of lanthanum (La) in the examples improves the oxygen transfer ability and promotes the decomposition of ammonium sulfate (ABS), and the formation of lanthanum sulfite (La ₂ (SO ₄ ) ₃ ) produces sulfur dioxide (SO ₂ ). It can be confirmed that durability is improved by consuming .

H ₂ -TPR analysis

H ₂ -TPR analysis of the denitrification catalyst prepared according to the above-described examples and comparative examples was performed, and the denitrification catalyst prepared according to the examples and comparative examples was heated to 400°C at a temperature increase rate of 10°C/min under atmospheric conditions. After pretreatment, it was cooled to 50°C.

Afterwards, H ₂ -TPR analysis was performed by reducing the catalyst while raising the temperature to 800°C at a temperature increase rate of 10°C/min under 5% H ₂ /Ar conditions.

Referring to FIG. 6, in the comparative example, hydrogen consumption peaks were confirmed at 372°C and 394°C, whereas in the example, unlike the comparative example, the peak formation temperature shifted to a lower temperature and was confirmed at 360°C and 383°C.

Therefore, it can be seen from the results in FIG. 6 that the oxygen transfer ability was improved due to the addition of lanthanum (La) to the example catalyst.

Raman analysis

In order to confirm the vanadium (V) structure of the denitrification catalyst prepared in the above-described examples and comparative examples, Raman analysis was performed, and the denitrification catalyst was measured in the 4,000-200 cm ^-1 region on a sample cut to a size of 2cm Infrared rays were applied to confirm the wavelength of Raman scattered light.

Referring to FIG. 7, it can be confirmed that a peak is generated at 795 cm ^-1 in Examples and Comparative Examples, and that the peak exists in the CeVO ₄ structure created by the combination of vanadium (V) and cerium (Ce). You can.

Table 1 shows the results of calculating the ratio of CeVO ₄ formed in the denitrification catalyst from the peak area through Raman analysis of the examples and comparative examples.

Example Comparative example CeVO ₄ structure ratio 4.84 One

Referring to the results in Table 1, the Example showed a CeVO ₄ area that was 4.8 times more than that of the Comparative Example. Through the above results, the Example showed that the oxygen transport ability was improved by strengthening the CeVO ₄ structure due to the addition of lanthanum (La). It indicates an increase.

Additionally, in Examples and Comparative Examples, peaks could be confirmed at 950 cm ^-1 to 1020 cm ^-1 , and it was confirmed that the active metal vanadium (V) exists in a polymer (oligomer) structure.

The areas of the vanadium polymer (oligomeric) structures of the examples and comparative examples were calculated, and the areas of the corresponding peaks were calculated and shown in Table 2.

Example Comparative example Vanadium polymer (oligomeric) structure ratio 2.2 One

Referring to the results in Table 2, the vanadium polymer (oligomeric) area was 2.2 times larger than that of the comparative example.

Through the above results, it can be confirmed that the oxygen transport ability of the example was increased by strengthening the vanadium polymer structure due to the addition of lanthanum (La).

SO ₂ -TPD analysis

In order to compare the degree of desorption of sulfur dioxide (SO ₂ ) adsorbed on the denitrification catalyst prepared in the above-described examples and comparative examples, NH ₃ gas was injected into a sample of the denitrification catalyst cut into a size of 2 cm x 2 cm for one hour at room temperature. After NH ₃ was adsorbed on the surface of the catalyst, the catalyst was purged and the amount of NH ₃ desorption according to temperature was analyzed using a mass analyzer to perform SO ₂ -TPD analysis. The results are shown in Figure 8.

Referring to FIG. 8, in the comparative example, a desorption peak of adsorbed sulfur dioxide (SO ₂ ) was confirmed at 650 to 750°C, whereas in the example, unlike the comparative example, a new peak was confirmed at 750 to 850°C.

From this, it can be seen that in the case of the denitrification catalyst of the example, the addition of lanthanum (La) resulted in the desorption of La sulfate (La ₂ (SO ₄ ) ₃ ) species formed by the reaction of sulfur dioxide (SO 2 ) and lanthanum _, and the formation of La sulfate species. This indicates that it contributed to improving durability by consuming sulfur dioxide (SO ₂ ).

Although the present invention has been described in detail through specific examples, this is for detailed explanation of the present invention, and the present invention is not limited thereto, and the present invention is intended to be understood by those skilled in the art within the technical spirit of the present invention. It is clear that modifications and improvements are possible.

All simple modifications or changes of the present invention fall within the scope of the present invention, and the specific scope of protection of the present invention will be made clear by the appended claims.

S10: Pre-fired body mixing step
S20: Preliminary body firing step
S30: Main mixture mixing step
S40: Main mixture calcination step

Claims (11)

A denitrification catalyst formed by vanadium and lanthanum being supported on a precalcined body made from tungsten oxide, cerium oxide, and titanium oxide.
According to paragraph 1,
A denitrification catalyst characterized by containing a CeVO ₄ crystal phase therein.
According to paragraph 2,
The CeVO ₄ crystal phase is,
A denitrification catalyst characterized in that it is linked to vanadium oxide in an oligomeric form.
According to paragraph 2,
A denitrification catalyst in which trivalent cerium contained within the CeVO ₄ crystal phase is 50 atomic% or less compared to the total cerium atoms contained in the entire catalyst.
According to paragraph 2,
A denitrification catalyst in which trivalent cerium and tetravalent cerium contained within the CeVO ₄ crystal phase are 60 atomic% to 80 atomic% compared to the total cerium atoms contained in the entire catalyst.
According to paragraph 1,
A denitrification catalyst characterized by a nitrogen oxide conversion rate of 70% or more at temperatures above 250°C and below 400°C.
According to paragraph 1,
A denitrification catalyst characterized in that the nitrogen oxide conversion rate is 80% to 90% of the initial level after 200 hours at 250℃ or higher and 400℃ or lower.
A pre-fired material mixing step of preparing a premix by mixing 5 parts by weight of a tungsten precursor and 5 parts by weight of a cerium precursor with 100 parts by weight of titanium oxide;
A pre-fired body firing step of producing a pre-fired body by firing the premix at a temperature of 550°C or more and 650°C or less;
A main reactor mixing step of preparing a main mixture by mixing 1.5 parts by weight of a vanadium precursor and 1 part by weight of a lanthanum precursor with respect to 100 parts by weight of the precalcined body; and
A main body sintering step of producing a denitrification catalyst by sintering the main mixture at a temperature of 450°C or more and 550°C or less;
A method for producing a denitrification catalyst comprising.
According to clause 8,
The titanium oxide is,
Method for producing a denitrification catalyst having an anatase crystal phase.
According to clause 8,
The vanadium precursor is,
Method for producing a denitrification catalyst of metavanadate (NH ₄ VO ₃ ).
According to clause 8,
The lanthanum precursor is,
Method for producing a denitrification catalyst of lanthanum nitrate (LaN ₃ O ₉ ).

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