KR20220089322A - Urea hydrolysis catalyst, production method thereof, and selective catalytic reduction system comprising the urea hydrolysis catalyst - Google Patents

Abstract

The present invention relates to a urea hydrolysis catalyst, a method for preparing the same, and a selective catalytic reduction system comprising the urea hydrolysis catalyst, wherein the urea hydrolysis catalyst comprises: a titania carrier; and niobium (Nb) supported on the Tinathia support, wherein the amount of moisture adsorbed per specific surface area of the catalyst is in the range of 6,000 to 9,000 H/m 2 .

Description

Urea hydrolysis catalyst, method for preparing the same, and selective catalytic reduction system comprising the same

The present invention relates to a urea hydrolysis catalyst, a method for preparing the same, and a selective catalytic reduction system comprising the urea hydrolysis catalyst, the urea hydrolysis catalyst having excellent urea decomposition performance without the formation of a salt, a method for preparing the same, and the urea It relates to a selective catalytic reduction system comprising a hydrolysis catalyst.

Nitrogen oxide (NOx) is a component of exhaust gas emitted from fixed sources such as chemical plants, power plants, boilers, and garbage incinerators, and from moving sources such as automobiles and ships, and is one of the harmful substances that cause air pollution. In particular, nitrogen oxides (NOx) cause not only acid rain or smog, but also ultrafine dust, and cause secondary pollution by generating various oxidizing agents such as O ₃ , HCHO, and PAN. In addition, recently, regulations on air pollution have been strengthened.

Accordingly, in the prior art, selective catalytic reduction (SCR) using ammonia as a reducing agent is mainly used as a method of removing nitrogen oxides emitted from a moving source. However, ammonia forms ammonium nitrate at a temperature of about 170 ° C. or less, which causes a problem that the selective catalytic reduction efficiency is rapidly reduced, and there is a risk of explosion and corrosion with a high concentration of ammonia water.

Instead of supplying ammonia directly to the selective catalytic reduction system, research is being conducted on supplying ammonia by using urea as a precursor for supplying ammonia. However, urea produces biuret, a by-product, in addition to ammonia at a temperature of about 200° C. or less, which may cause difficult-to-decompose salts.

In order to solve this problem, research on the urea injection system is being conducted, but there is a limit to increasing the ammonia conversion rate of urea only with the urea injection system.

It is an object of the present invention to provide a urea hydrolysis catalyst capable of improving the decomposition efficiency of urea while suppressing the formation of salts during the decomposition of urea, and a method for preparing the same.

Another object of the present invention is to provide a selective catalytic reduction system comprising the above-mentioned urea hydrolysis catalyst.

In order to achieve the above object, the present invention is a titania carrier; and niobium (Nb) supported on the Tinathia support, wherein the moisture adsorption amount per specific surface area of the catalyst is in the range of 6,000 to 9,000 H/m 2 , and a urea hydrolysis catalyst.

In addition, the urea hydrolysis catalyst of the present invention may further include ceria (CeO ₂ ) supported on the titanid carrier.

In addition, the present invention provides a selective catalytic reduction system comprising the above-described urea hydrolysis catalyst.

In addition, the present invention comprises the steps of forming a slurry by adding a niobium precursor aqueous solution to a titinia carrier; and drying the slurry, and calcining at a temperature of 400 to 800° C. for 1 to 8 hours.

In addition, in the preparation method, an aqueous solution of a ceria precursor may be further added to the tinathia carrier when the slurry is formed.

The present invention can improve the decomposition efficiency of urea while suppressing the formation of salts during the decomposition of urea. Accordingly, the present invention can improve the removal efficiency of nitrogen oxides when applied to a selective catalytic reduction system.

1 is a graph showing the reaction temperature-urea to ammonia conversion rate for the catalysts of Examples 1 and 3 and Comparative Examples 1 and 2;
2 is a H ₂ -TPR analysis graph for the urea hydrolysis catalysts of Examples 1 and 3;
3 is a H ₂ O-IR DRIFT graph for the catalysts of Examples 1 and 3 and Comparative Examples 1-2.
4 is a graph showing the amount of moisture adsorption per catalyst specific surface area-urea to ammonia conversion rate for the catalysts of Examples 1 to 3 and Comparative Examples 1 to 8;
5 is a graph showing the reaction temperature-urea to ammonia conversion rate for the urea hydrolysis catalyst of Examples 1 and 2;
6 is a graph showing the ammonia conversion rate of urea for a catalyst prepared by adding Nb, Sb, Cu, W, and Zr to a titania carrier [TiO ₂ (A)], respectively.

EMBODIMENT OF THE INVENTION Hereinafter, this invention is demonstrated.

In general, urea (urea) is a precursor for supplying ammonia, and is converted into ammonia through the thermal decomposition reaction of Reaction Scheme 1 and the hydrolysis reaction of Reaction Scheme 2 below.

[Scheme 1]

[Scheme 2]

During the decomposition of urea, if the hydrolysis reaction does not occur properly after the thermal decomposition reaction, isocyanic acid (HNCO) re-reacts with urea to generate a by-product, biuret[(H ₂ NCO) ₂ NH], which is difficult to decompose. causes salt. For this reason, not only the production efficiency of ammonia falls, but also SCR efficiency can be reduced by damaging the denitration facility apparatus, such as a nozzle, a piping, and a catalyst surface.

Therefore, in the present invention, in order to increase the hydrolysis reaction rate, a catalyst in which niobium (Nb) is supported on a titania carrier was used as a urea hydrolysis catalyst. At this time, the present inventors recognized that the amount of moisture (H ₂ O) adsorption of the urea hydrolysis catalyst acts as a hydrolysis reaction factor of HNCO. Specifically, when water is adsorbed on the surface oxygen vacancies of the urea hydrolysis catalyst, hydrogen atoms of the adsorbed water molecules interact with NH groups of HNCO to generate ammonia (NH ₃ ).

Accordingly, in the present invention, a catalyst in which niobium (Nb) is supported on a titania carrier is used as a urea hydrolysis catalyst, but the water adsorption amount per specific surface area of the catalyst is adjusted in the range of about 6,000 to 9,000 H/m 2 , thereby improving the hydrolysis reaction rate Thus, the efficiency of ammonia production can be improved without the formation of salts.

In one example, the urea hydrolysis catalyst of the present invention may include a titania carrier; and niobium (Nb) supported on the Tinathia support, wherein the amount of moisture adsorbed per specific surface area of the catalyst is in the range of 6,000 to 9,000 H/m 2 . In addition, the urea hydrolysis catalyst of the present invention may optionally further include ceria (CeO ₂ ).

In the urea hydrolysis catalyst of the present invention, niobium (Nb) is an active component of the catalyst, and may be supported on a titania carrier to increase the conversion rate of urea into ammonia.

The content of such niobium is not particularly limited, and for example, may be in the range of about 1 to 3 wt% based on the total amount of the urea hydrolysis catalyst. If the content of niobium is within the above-described range, the catalyst activity per unit weight (or volume) is excellent, so that the urea decomposition efficiency can be improved.

In the urea hydrolysis catalyst of the present invention, the titania carrier is a component supporting the catalytically active component, and consists of titania.

Such titania carriers may contain an anatase crystalline phase, or may contain an anatase crystalline phase and a rutile crystalline phase. However, when the titania carrier contains an anatase crystal phase and a rutile crystal phase, the ammonia conversion rate of urea may be further improved compared to the case where the titania carrier contains only the anatase crystal phase. In addition, the titania carrier containing the anatase crystal phase and the rutile crystal phase has excellent water adsorption ability, compared to the titania carrier containing only the anatase crystal phase, despite less surface oxygen, so that the ammonia conversion rate of urea can be further improved.

The titania carrier containing the anatase crystal phase and the rutile crystal phase may contain the anatase crystal phase and the rutile crystal phase in a weight ratio of 60:40 to 80:20.

The specific surface area of the titania carrier is not particularly limited, and for example, the BET specific surface area may be in the range of about 40 to 80 m 2 /g.

The content of the titania carrier is not particularly limited and may be, for example, the remaining amount adjusted so that the total amount of the catalyst is 100% by weight.

In the urea hydrolysis catalyst of the present invention, ceria (CeO ₂ ) is supported on a titania carrier as a cocatalyst component. By further including such ceria, the activity of the urea hydrolysis catalyst can be improved, so that the conversion rate of urea to ammonia can be increased, and the thermal stability of the catalyst can be improved.

The content of the ceria is not particularly limited, and for example, may be in the range of about 9 to 11 wt% based on the total amount of the urea hydrolysis catalyst.

The urea hydrolysis catalyst of the present invention described above may have an ammonia conversion rate of urea of 90% or more at 190 ° C. or higher (specifically, 190 to 250 ° C.). Therefore, when the urea hydrolysis catalyst of the present invention is disposed in the urea injection line of the selective catalytic reduction system, the conversion of urea to ammonia proceeds very quickly, thereby improving the removal efficiency of nitrogen oxides.

Meanwhile, the present invention provides a method for preparing a urea hydrolysis catalyst.

For example, the urea hydrolysis catalyst of the present invention may be prepared using an impregnation method for supporting niobium on titania as a carrier.

Specifically, the urea hydrolysis catalyst (S100) forming a slurry by adding an aqueous solution of a niobium precursor to a titinia carrier; and (S200) drying the slurry and calcining at a temperature of 400 to 800° C. for 1 to 8 hours.

Hereinafter, each step of the method for preparing the urea hydrolysis catalyst according to the present invention will be described.

(S100) step: slurry formation step

An aqueous niobium precursor solution is added to the titinia carrier to form a slurry.

In step (S100), a niobium precursor is dissolved in water to form an aqueous niobium precursor solution, and then a slurry is obtained by mixing the formed aqueous solution of the niobium precursor with a titania carrier.

The niobium precursor usable in the present invention includes niobium oxalate hydrate (C ₁₀ H ₅ NbO ₂₀ ·xH ₂ O), and the like, but is not limited thereto.

The content of the niobium precursor is not particularly limited, and for example, may be in the range of about 1 to 5 parts by weight based on 100 parts by weight of the titinia carrier.

The mixing time (stirring time) of the aqueous solution of the niobium precursor and the titania carrier is not particularly limited, and may be about 1 hour or more, specifically, about 1 to 2 hours.

Optionally, when forming the slurry in step (S100), an aqueous solution of a ceria precursor may be further added to the Tinatia carrier. At this time, the ceria precursor aqueous solution is obtained by dissolving the ceria precursor in water.

The ceria precursor usable in the present invention includes cerium nitrate (Ce(NO ₃ ) ₃ ·xH ₂ O), but is not limited thereto.

The content of the ceria precursor is not particularly limited, and may be, for example, about 1 to 11 parts by weight based on 100 parts by weight of the titania carrier.

(S200) step: drying and firing of the slurry

The slurry obtained in step (S100) is dried, and then calcined at a temperature of about 400 to 800° C. for 1 to 8 hours to obtain a urea hydrolysis catalyst.

The drying process may be performed using a vacuum evaporator. As an example, the slurry can be heated at a temperature of about 55 to 75 ° C to remove moisture, and then optionally, heated at a temperature of about 95 to 115 ° C for 12 hours or more (specifically, about 12 to 15 hours) Moisture can be completely removed.

When the calcination process is performed at too high a temperature, the specific surface area of the catalyst may be small, and thus the amount of moisture adsorption may be small. Therefore, in the present invention, by controlling the calcination temperature to be in the range of about 400 to 600 ° C, specifically, about 500 to 600 ° C, the moisture adsorption amount per specific surface area of the final urea hydrolysis catalyst is in the range of about 6,000 to 9,000 H / m 2, urea The decomposition efficiency can be improved.

At this time, the calcination time is adjusted according to the temperature, and may be, for example, about 1 to 8 hours, specifically 2 to 4 hours.

Such a firing process may use various types of furnaces commonly known in the art, such as a tube-type furnace, a convection-type furnace, a grate-type furnace, and the like.

Hereinafter, the present invention will be described in more detail through examples. However, the examples are for illustrating the present invention, and the present invention is not limited thereto.

<Example 1>

A titania carrier (P-25, manufactured by Evonik Aeroxide, hereinafter, 'TiO ₂ (A) carrier') in which anatase-type and rutile-type coexist was prepared. On the other hand, Niobium (V) oxalate hydrate (C ₁₀ H ₅ NbO ₂₀ ·xH ₂ O) was dissolved in water to form a niobium precursor aqueous solution. At this time, the niobium precursor was used in an amount of about 2 parts by weight based on 100 parts by weight of the TiO ₂ (A) carrier. Then, the niobium precursor aqueous solution was added to the TiO ₂ (A) carrier and stirred for approximately 1 hour to form a slurry. Thereafter, the slurry was heated to a temperature of about 65 ° C. using a vacuum evaporator to remove moisture, and then dried at a temperature of about 105 ° C. for 12 hours or more to completely remove moisture, and then the slurry was heated to a temperature of about 600 ° C. A urea hydrolysis catalyst composed of niobium/titania [hereinafter, 'Nb[2]/TiO ₂ (A)'] was prepared by calcination for a period of time.

<Example 2>

In Example 1, the niobium precursor aqueous solution and the ceria precursor aqueous solution were added to the TiO ₂ (A) carrier instead of adding the niobium precursor aqueous solution to the TiO ₂ (A) carrier. In the same manner as in Example 1, niobium- A urea hydrolysis catalyst composed of ceria/titania [hereinafter, 'Nb[2]-Ce[10]/TiO ₂ (A)'] was prepared. At this time, the ceria precursor aqueous solution is prepared by dissolving Cerium(III) nitrate hexahydrate (Ce(NO ₃ ) ₃ .xH ₂ O) in water, and the content of Cerium(III) nitrate hexahydrate is TiO ₂ (A) carrier 100 weight It was about 10 parts by weight based on parts.

<Example 3>

Except for using the TiO ₂ (B) carrier instead of the TiO ₂ (A) carrier used in Example 1, in the same manner as in Example 1, a urea hydrolysis catalyst composed of niobium/titania [hereinafter referred to as ‘Nb [ 2]/TiO ₂ (B)'] was prepared. The TiO ₂ (B) carrier used at this time was DT-51 from Cristalactive, which was anatase-type titania.

<Comparative Example 1>

Titania (P-25 from Evonik Aeroxide, anatase type and rutile type coexist) [hereinafter, 'TiO ₂ (A)'] was used as Comparative Example 1.

<Comparative Example 2>

Titania (DT-51 of Cristalactive, anatase type) [hereinafter, 'TiO ₂ (B)'] was used as Comparative Example 2.

<Comparative Example 3>

Titania (P-25 from Evonik Aeroxide, anatase type and rutile type coexist) [hereinafter, 'TiO ₂ (A)'] was calcined at 300 ° C. in an air atmosphere for 4 hours to urea hydrolysis catalyst [hereinafter , 'TiO ₂ (A) 300cal-4hr'] was prepared.

<Comparative Example 4>

Titania (Evonik Aeroxide's P-25, anatase type and rutile type coexist) [hereinafter, 'TiO ₂ (A)'] was calcined for 4 hours at 400 ℃ in an air atmosphere to urea hydrolysis catalyst [hereinafter , 'TiO ₂ (A) 400cal-4hr'] was prepared.

<Comparative Example 5>

Titania (P-25 from Evonik Aeroxide, anatase type and rutile type coexist) [hereinafter, 'TiO ₂ (A)'] was calcined at 500 ° C. in an air atmosphere for 4 hours to urea hydrolysis catalyst [hereinafter , 'TiO ₂ (A) 500cal-4hr'] was prepared.

<Comparative Example 6>

Titania (Evonik Aeroxide's P-25, anatase type and rutile type coexist) [hereinafter, 'TiO ₂ (A)'] was calcined at a temperature of 600 ℃ in an air atmosphere for 4 hours to urea hydrolysis catalyst [hereinafter , 'TiO ₂ (A) 600cal-4hr'] was prepared.

<Comparative Example 7>

Titania (P-25 from Evonik Aeroxide, anatase type and rutile type coexist) [hereinafter, 'TiO ₂ (A)'] was calcined at 700 ° C. in an air atmosphere for 4 hours to urea hydrolysis catalyst [hereinafter , 'TiO ₂ (A) 700cal-4hr'] was prepared.

<Comparative Example 8>

Titania (P-25 from Evonik Aeroxide, anatase type and rutile type coexist) [hereinafter, 'TiO ₂ (A)'] was calcined at 800 °C in an air atmosphere for 4 hours to urea hydrolysis catalyst [hereafter , 'TiO ₂ (A) 800cal-4hr'] was prepared.

<Experimental Example 1> - Urea decomposition efficiency according to the urea reaction temperature of the urea hydrolysis catalyst

In order to check the urea decomposition efficiency according to the urea reaction temperature of the urea hydrolysis catalysts prepared in Examples 1 and 3 and Comparative Examples 1 and 2, urea is converted to ammonia under a space velocity condition of 60,000 hr ^-1 and ammonia produced After measuring the amount of produced, the conversion rate of urea to ammonia (Urea to NH ₃ conversion, %) was calculated according to Equation 1 below. The results are shown in FIG. 1 . Here, the space velocity is an index indicating the amount of target gas that the catalyst can process, and is expressed as the ratio of the volume of the catalyst to the total gas flow rate (volume).

** EXPERIMENTAL CONDITIONS **

- Urea concentration: 400 ppm,

- Oxygen content: 3.0 vol.%,

- Carrier gas inlet flow rate: 1000 cc/min;

- Space velocity: 60,000 hr ^-1 ,

- Amount of urea hydrolysis catalyst used: 0.5 g,

- Retention time: 0.12 seconds

- Reaction temperature: 190 ~ 250 ℃

[Equation 1]

(In Equation 1 above,

C _outletNH3 is the amount of ammonia produced,

C _inleturea is the supply of urea).

As can be seen from FIG. 1 , the urea hydrolysis catalysts of Examples 1 and 3 had a higher conversion rate of urea to ammonia at a reaction temperature of about 190 to 250° C. compared to the catalysts of Comparative Examples 1 and 2 . In particular, the urea hydrolysis catalyst of Example 1 was about 90% or more at a reaction temperature of about 190 to 250 °C, and the conversion rate of urea to ammonia was very excellent.

From this, the urea hydrolysis catalyst according to the present invention has excellent decomposition efficiency of urea at high temperature. In addition, it was found that the ammonia conversion rate of urea was higher when titania coexisting with anatase crystal phase and rutile crystal phase was used as a carrier, compared to the case where titania having only anatase crystal phase was used as a carrier.

<Experimental Example 2> - Relationship between urea decomposition performance and oxygen transfer ability of the urea hydrolysis catalyst

Regarding the performance of the urea hydrolysis catalyst according to the present invention, the oxygen transfer ability and moisture adsorption capacity were tested as follows, and the results are shown in FIGS. 2 and 3 , respectively.

(1) H ₂ -TPR analysis

H _{2 -temperature programmed reduction (H 2 -TPR} ) analysis was performed on the urea hydrolysis catalysts of Examples 1 and 3, and the results are shown in FIG. 2 .

H ₂ -TPR analysis confirmed the degree of reduction to TCD signal by raising the temperature of the urea hydrolysis catalyst from room temperature to 700 °C at a rate of 10 °C/min in a reducing atmosphere.

As can be seen from FIG. 2, the urea hydrolysis catalyst of Example 1 had almost no hydrogen consumption compared to the urea hydrolysis catalyst of Example 2. At this time, the urea hydrolysis catalyst of Example 1 did not show a reduction peak at 100 to 600 °C, unlike the urea hydrolysis catalyst of Example 2.

(2) H in urea catalyst ₂ O-IR DRIFT profile

Each catalyst was subjected to an IR DRIFT (Diffuse Reflectance Infrared Fourier Transform Spectroscopy) test for moisture adsorption characteristics of the catalyst while injecting H ₂ O / N ₂ balance wet gas for 30 minutes at 190 ° C. (10 ° C./min temperature rise). The adsorption capacity was observed.

In FIG. 3 , the urea hydrolysis catalyst of Example 1 had a higher O-H group compared to the catalyst of Comparative Example 1, and thus had high moisture adsorption, and the urea hydrolysis catalyst of Example 2 had a higher O-H group compared to the catalyst of Comparative Example 2 Moisture adsorption was high. On the other hand, the catalyst of Comparative Example 1 had a higher moisture adsorption rate than the catalyst of Comparative Example 2.

From this, it was found that when the titania carrier containing the anatase crystal phase and the rutile crystal phase was included, the moisture adsorption capacity of the catalyst was excellent. In addition, it was found that when Nb was supported on the titania carrier, the moisture adsorption capacity of the catalyst was excellent.

(3) Through the above-described H ₂ -TPR analysis and H ₂ O-IR DRIFT profile, it was found that the urea hydrolysis catalyst according to the present invention has excellent adsorption capacity.

<Experimental Example 3> - Relationship between urea decomposition performance and moisture of the urea hydrolysis catalyst

In order to confirm the relationship between the urea decomposition performance and moisture of the urea hydrolysis catalyst according to the present invention, the ammonia conversion rate of urea relative to the moisture adsorption amount per catalyst specific surface area for the urea hydrolysis catalysts of Examples 1 to 3 and Comparative Examples 1 to 8 was measured, and the results are shown in FIG. 4 . In FIG. 4, i) Nb/TiO ₂ (A), Nb-Ce/TiO ₂ (A), and Nb/TiO ₂ (B) are the urea reaction catalysts of Examples 1 to 3, respectively, ii) TiO ₂ (A ), TiO ₂ (B) is a catalyst of Comparative Examples 1 and 2, respectively, iii) TiO ₂ (A) 300cal-4hr, TiO ₂ (A) 400cal-4hr, TiO ₂ (A) 500cal-4hr, TiO ₂ ( A) 600cal-4hr, TiO ₂ (A) 700cal-4hr, TiO ₂ (A) 800cal-4hr represents the catalysts of Comparative Examples 3 to 8, respectively.

Here, the ammonia conversion rate of urea is the result of the batch reaction. After mortar mixing of urea and urea hydrolysis catalyst in a weight ratio of 1:0.01, the temperature is raised from room temperature to 500 °C at a rate of 10 °C/min to determine the amount of ammonia produced. After measurement, it is a value calculated according to Equation 1 above. On the other hand, the amount of moisture adsorption per catalyst specific surface area is a value obtained by dividing the amount of moisture adsorption by the specific surface area of the catalyst. BET analysis was performed for the specific surface area of the catalyst.

1) As can be seen from FIG. 4, when the urea hydrolysis catalyst of Examples 1 to 3 has a moisture adsorption amount per catalyst specific surface area of 6,000 to 9,000 H/m 2 , the ammonia conversion rate of urea compared to the catalysts of Comparative Examples 1 and 2 this was higher In particular, the urea hydrolysis catalysts of Examples 1 and 2 using a titania carrier containing an anatase crystal phase and a rutile crystal phase as carriers are ammonia of urea compared to the urea hydrolysis catalyst of Example 3 using a titania carrier containing only an anatase crystal phase. The conversion rate was higher.

2) On the other hand, the catalysts of Comparative Examples 3 to 8 had different calcination temperatures of 300 to 800° C., and they had different moisture adsorption amounts per catalyst specific surface area and, accordingly, urea to ammonia conversion rates were also different.

From this, it was indirectly found that the urea hydrolysis catalyst of the present invention has a different amount of moisture adsorption per catalyst specific surface area depending on the calcination temperature at the time of manufacture, which also affects the ammonia conversion rate of urea.

<Experimental Example 4>

In order to confirm the urea decomposition efficiency according to the urea reaction temperature of the urea hydrolysis catalyst prepared in Examples 1 and 2, the amount of ammonia produced by converting urea into ammonia under a space velocity condition of 240,000 hr ^-1 was measured. , The ammonia conversion rate of urea (Urea to NH ₃ conversion, %) was calculated according to Equation 1 above. The results are shown in FIG. 5 .

** EXPERIMENTAL CONDITIONS **

- Urea concentration: 400 ppm,

- Oxygen content: 3.0 vol.%,

- Carrier gas inlet flow rate: 1,000 cc/min;

- Space velocity: 240,000 hr ^-1 ,

- Amount of urea hydrolysis catalyst used: 0.5 g,

- Retention time: 0.02 seconds

- Reaction temperature: 190 ~ 250 ℃

As can be seen from FIG. 5 , the urea hydrolysis catalyst of Example 2 had a higher conversion rate of urea to ammonia than the urea hydrolysis catalyst of Example 1. In particular, at a reaction temperature of 200° C. or higher, the urea hydrolysis catalyst of Example 2 had a urea to ammonia conversion rate of about 90%.

<Experimental Example 5>

In order to confirm the performance of the urea hydrolysis catalyst according to the present invention, Nb, Sb, Cu, W, and Zr were respectively added to the titania carrier [TiO ₂ (A)] (P25 of Evonik Aeroxide) and calcined. Next, the conversion rate of urea to ammonia for each catalyst was measured. At this time, the amount of each metal added was about 2 parts by weight based on 100 parts by weight of the TiO ₂ (A) carrier. On the other hand, the ammonia conversion rate of urea with respect to the titania carrier [TiO ₂ (A)] (P25 of A company) was also measured. The measurement results are shown in FIG. 6 .

As can be seen in Figure 6, the catalyst (Nb[2]/P-25) prepared by adding Nb to the titania carrier [TiO ₂ (A)] is added with different metals (Sb, Cu, W, Zr) Compared to catalysts Sb[2]/P-25, Cu[2]/P-25, W[2]/P-25, Zr[2]/P-25) prepared by .

From this, it was confirmed that the urea hydrolysis catalyst according to the present invention has excellent decomposition performance of urea.

Claims (14)

titania carrier; and niobium (Nb) supported on the Tinathia support, wherein the moisture adsorption amount per specific surface area of the catalyst is in the range of 6,000 to 9,000 H/m 2 , the urea hydrolysis catalyst. According to claim 1,
Ceria supported on the titania carrier (CeO ₂ ) Will further include a urea hydrolysis catalyst. 3. The method of claim 2,
The content of the ceria is in the range of 9 to 11% by weight based on the total amount of the urea hydrolysis catalyst, the urea hydrolysis catalyst. According to claim 1,
The content of the niobium is in the range of 1 to 3% by weight based on the total amount of the urea hydrolysis catalyst, the urea hydrolysis catalyst. According to claim 1,
The titania carrier is an anatase (anatase) crystalline phase; or an anatase crystal phase and a rutile crystal phase. 6. The method of claim 5,
The titania carrier contains an anatase crystal phase and a rutile crystal phase in a weight ratio of 60:40 to 80:20, the urea hydrolysis catalyst. According to claim 1,
A urea hydrolysis catalyst, wherein the ammonia conversion of urea is 90% or more under a temperature of 190 ° C. or higher. A selective catalytic reduction system comprising the urea hydrolysis catalyst according to any one of claims 1 to 7. adding an aqueous niobium precursor solution to the titinia carrier to form a slurry; and drying the slurry, and calcining at a temperature of 400 to 800° C. for 1 to 8 hours.
A method for producing a urea hydrolysis catalyst comprising a. 10. The method of claim 9,
The niobium precursor of the niobium precursor aqueous solution is niobium oxalate hydrate (C ₁₀ H ₅ NbO ₂₀ ·xH ₂ O), a method for producing a urea hydrolysis catalyst. 11. The method of claim 10,
The method for producing a urea hydrolysis catalyst, wherein the niobium precursor in the aqueous solution of the niobium precursor is used in an amount of 1 to 5 parts by weight based on 100 parts by weight of the titinia carrier. 10. The method of claim 9,
When forming the slurry,
A method for preparing a urea hydrolysis catalyst by further adding an aqueous solution of a ceria precursor to the tinatia support. 13. The method of claim 12,
The ceria precursor of the ceria precursor aqueous solution is cerium nitrate (Ce(NO ₃ ) ₃ ·xH ₂ O), a method for producing a urea hydrolysis catalyst. 13. The method of claim 12,
The ceria precursor of the aqueous ceria precursor solution is used in an amount of 1 to 11 parts by weight based on 100 parts by weight of the titinia carrier, the method for producing a urea hydrolysis catalyst.

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